Components of service value in business-to-business Cloud Computing Cloud computing services are used in many businesses. However, little is known about the components of service value in B2B cloud computing services from a customer perspective. In the B2C service literature, service value has four components: customer perceptions of the quality, equity, benefits, and sacrifices for the delivered service. The purpose of this research is to determine whether the components from an established B2C model applies to B2B cloud computing services. We followed a qualitative approach and interviewed twenty-one managers responsible for handling cloud computing services and for the decision to repurchase services. The interviews were then analysed to determine whether the existing model covers cloud computing services completely. We found broad support for the established service value components in a B2B cloud computing context. Importantly, we found evidence for a fifth component we called "cloud service governance". A deeper understanding of service value perceptions among business users of cloud computing services means vendors can measure this for their customers. This is important because perceptions of service value directly influences customer satisfaction, impacting the buyer's intention to repurchase the service. Similarly, this study will help buyers of B2B cloud computing services to assess the value extracted from their cloud computing service relationships. It will also help cloud providers and new competitors focus their efforts (e.g., into increasing technical reliability) to improve their customers' perceptions of value obtained from their cloud computing services. This research advances the literature by extending the established B2C service value model to the context of B2B cloud computing, and providing the first evidence of an extra component in B2B services more generally. The "anytime, anywhere" [1] concept of access to large data storage spaces, increased processing power and convenience in computing growth, led to the development [2, 3] and adoption of technology [4, 5] for cloud computing [6] . In 2006, Amazon.com, a popular online retailer, started an organisation called Amazon Web Services (AWS), offering cloud computing services. During the early adoption of AWS, it was observed that the service consistencies of specific cloud computing services greatly impact the service experiences of the customer [7] .. As far as the customer is concerned, cloud computing services are made possible through non-specialised devices such as desktop computers, smartphones, tablets and other hardware devices capable of running a Web browser [8] . Further, cloud computing services are variously provided to individual customers (these are called B2C cloud-computing services) or to other business customers (which are called B2B cloud-computing services). In this paper, we focus on the latter business customers.. Three main types of service are offered to business customers of cloud providers [9, 10] . Firstly, Software as a Service (SaaS) enables a subscriber to utilise applications offered within the cloud infrastructure. Secondly, Platform as a Service (PaaS), allows a subscriber to deploy and control applications within the cloud infrastructure. Thirdly, Infrastructure as a Service (IaaS) enables a customer to utilise the cloud infrastructure to deploy and run operating systems and numerous applications. A cloud provider is an organisation that provides any of these types of cloud services.. The basic problem may be succinctly stated: The service value of cloud computing in business-to-business context can and does fail where perceptions are ignored by service managers. Although the movement from published literature has been slow, subsequent empirical research has supported this broad claim [11] that there is a need to understand and measure service value for business generally. In order to have a well-rounded appreciation of service value for cloud computing business users we have obtained the perspectives of service managers who are responsible for cloud computing services in their organisations. This paper focuses more on the service value perceptions by business users of cloud computing rather than on objective technical measures, for example, 99.999 % assurance levels. Through the contribution of this research, we attempt to provide a richer understanding of the service value perceptions, and thus equipping service managers with a fullyrounded view as they integrate their understanding with technical measures.. Cloud providers recognise the importance of focusing efforts towards their customers [12] . A majority of these providers understand that competitive advantage will not stem from simply selling cloud services to other businesses but in the continued accumulation of value throughout the relationship with their business customers [13] . Understanding service value allows cloud providers and customers to better understand the costs and benefits of the service relationship [11, 14] . However, the determination of the components of the service value perceptions in business-to-business cloud computing in practise and theory, however, has been problematic. There is lack of knowledge regarding the relevant components of service value as appropriate in business-to-business context of cloud computing. This situation supports the findings of researchers involving the study of multiple components of service value that fail to precisely conceptualise the constructs [15] . The problem arises when conceptual models are used that were believed to apply in other service contexts. The detailed investigations by conducting empirical research (e.g., qualitative in-depth interviews) into the components, comprising a specific model, are then necessary. In order to determine the components of service value, we adopted and modified the Ruiz, Gremler, Washburn and Carrión [16] service value model. Their research recommended additional work to examine "service value differences across contexts" ( [16] , p.1289), wherein this paper addressed that call. The mentioned model describes the focus on the role of dissimilar components of service value that varies depending on the interpretation of the customer. As their service value model was developed and applied to a business-to-consumer setting, this paper augmented the established service value model, and made it more appropriate in a business-to-business context of cloud computing. This paper therefore seeks to fill in that gap by addressing the following research question:. What are the components of service value in business-tobusiness cloud computing?. To answer the research question, we interviewed senior managers from 21 companies, each of whom are responsible for deciding whether to re-purchase existing B2B cloud computing services. The focus of this study is to determine the perceptions of service value from the standpoint of business customers using cloud computing services. Thus, there are limited discussions regarding technical aspects as the attention is on non-technical matters, which will be made apparent in the analysis and results section of this manuscript. The participants all had extensive expertise and experience in managing and deciding on any IT-related services, more specifically on cloud computing. In the interviews, we did explore how the established components of service value existing in the B2C context apply to a different (business-to-business) context. As such, we investigated how the various service value components have been perceived and articulated by customers, who are decision-makers within their respective organisations and are representing diverse industries, of cloud computing. We explored, and successfully obtained the customers' perceptions. Apart from confirming that the established service value model in B2C do apply in a B2B context, we have uncovered an extra contextual component which did not fit the other components of the established model. This additional component called cloud service governance formed one of the service value components in the business context. The National Institute of Standards and Technology or NIST [9] , a US-based organisation responsible for creating the most referred cloud computing definition, provided one of the general recommendations on governance. The term IT governance refers to "broader corporate governance principles…focusing on the management and use of IT in order to achieve corporate performance goals" ( [17] , p.4). This principle then refers to organisations aligning their IT-related actions, such as managing cloud computing services, in relation to the respective business objectives of the relevant decision makers. One of the management principles, as stated through the recommendations of NIST [9] , is migrating data out of and into the cloud computing infrastructure.. The increasing prevalence of cloud computing services provided to business customers requires a better understanding of service value as perceived by customers. Indeed, the widespread use of cloud computing services has been increasingly compared to our consumption of public utilities. Also, while customers are using cloud computing, they are utilising the respective services (e.g., data storage as part of the broader Infrastructure as a Service offering), which may be for personal use or as part of their organisational needs. The term "customer" in this paper refers to an organisational user, and does not refer to an individual who purchases and utilises a product or a service for individual consumption [18] . This paper proceeds as follows. First, we introduce the dimensions of service value, as found in the service marketing literature. Second, we describe the research design for the study. Third, we analyse the results of the interviews before concluding with the components of service value as it applies in B2B cloud computing services. The purpose of this study is to determine the components of service value in the context of B2B cloud computing services. This section discusses the findings based on analysis of the interviews we conducted with managers responsible for repurchasing B2B cloud services. We review the components of service value explored during the study and note implications, limitations and future directions.

O O B I O B B I B I O O O O O O O O O O O O O O B I O O B I O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O B I O O O O B I O O O O O O O O O O O B I I O O O O B I O O O O O B I O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O B I O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O B I O O O O O O O O O O O O O O B I O O O O O O O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B B I O O O O O O O O O O O O O O O O O O B I O O O B O O B I O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O O O O O O O B I O O O O O O O O B O O B I O O O O O O O O O O O O O O O O O O O O B I O O B I O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O B I O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O O B O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O B I O O O O O O O O O O B I O O O O O O O O O B I O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O B I O O O O O O O O O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O


Towards lightweight checks for mass maintenance transformations We propose a lightweight, practical approach to check mass maintenance transformations. We present checks for both transformation tools and transformed source code, and illustrate them using examples of real-world transformations. Our approach is not a fully fledged, formal one but provides circumstantial evidence for transformation correctness, and has been applied to the mass maintenance of industrial Cobol systems. Transformations are very important for software engineering. Compilers, code generation, code analysis, automated modifications and refactoring are only a few examples of commonly known transformations. The use of transformations has gradually increased in the field of software maintenance. For example, code analysis tools have become more and more indispensable to maintain large systems, and large-scale modifications, such as Euro conversions, Y2K repairs or database migrations, have called for automated maintenance transformations [28] .. The increasing interest in automated maintenance has heightened the need for control over automatic transformations. For instance, automated changes on business-critical systems should not jeopardize the operations of a company. Such changes usually consist of several complex transformations, affecting millions of lines of code. So it is not very practical to inspect the result of a mass update by hand. An alternative, extensive testing of the transformed code, is expensive and not always feasible in practice. Massive automated changes are often carried out by software renovation companies, and they usually do not possess the required hard-and/or software to, for instance, compile and test a mainframe system. Although the owner of the system has a suitable compiler, mainframes are delivered with a fixed calculation capacity. The employment of this capacity for finding errors in (automated) changes is expensive (see [7] for figures on costs for compiling large systems), so possible errors should be detected in an early stage. Therefore, additional ways are needed to control such transformations.. Some people think that it is feasible to prove the correctness of a mass maintenance transformation on millions of lines of code in advance. However, correctness proofs are time-consuming and often impractical for mass maintenance transformations. We will explain this with some examples.. In order to deploy correctness proofs, one needs the semantics of the used programming language. These have not been defined for every programming language, in particular legacy languages like Cobol. For these languages, it is even not possible to capture the semantics. There are many different dialects, compilers, compiler flags and operating systems, and thus there is no single semantics for these languages. This is an important issue, and is discussed in [19, 20] ; since it is not common knowledge that it is not possible to capture a single semantics, we show some of the given examples here. Consider the following Cobol fragment, taken from [19, p. This fragment illustrates differences between two compilers. The OS/VS Cobol compiler prints the expected result, namely ' IEEE', which is right justified, whereas the Cobol/370 compiler displays the output 'IEEE ' with a trailing space, which is left justified. The second example illustrates differences within a single compiler, and is also taken from [19, p. Depending on the compiler flags, this code displays the number '3123123' or the entirely different number '1231231'. There are many more similar examples, for instance, the precise semantics of the behaviour of procedures in Cobol is compiler-dependent [9, p. 2] . It is expensive and error prone to deal with all variants, as also stated in [19] , so to summarise there is no 'the semantics'.. On the other hand, one could capture a subset of the semantics for a specific maintenance project with a specific Cobol dialect, compiler and operating system, i.e. relevant for a particular modification [3] . However, using a formal approach can still be an expensive process and prone to errors, and as soon as something changes (e.g. compiler version or operating system version) a different semantics needs to be developed. So it is not surprising that the ROI on correctness proofs is negative [14, p. 108] . Moreover, in mass maintenance projects it is often the goal to modify the functionality of a system, rendering a semantics preserving approach not useful. Furthermore, in addition to proving the transformations correct, one would also have to prove the rest of the transformation process correct, for instance the preprocessor, parser and prettyprinter and so on. For these reasons, a correctness proof for mass maintenance transformations on legacy systems is too expensive and not practical, and we need other ways to make sure the updated systems behave as expected.. The aim of this research is to provide a lightweight approach to check large-scale maintenance transformations. We present a range of checks to identify errors in transformations quickly and at low cost, and these checks are applied in two mass maintenance projects. We presented a lightweight approach to check mass maintenance transformations by proposing several practical checks for detecting errors. Our approach does not prove correctness of transformations but it is an effective way to have control over mass maintenance transformations and to detect errors, and it provides circumstantial evidence for transformation correctness.. In our approach, we proposed separate checks for transformation rules and for program code, which can be performed in a semi-automatic way. Each check aims at different types of errors in different phases of a transformation process. Five checks were proposed and implemented: CFI to detect errors in control-flow preserving transformations by automatically comparing control-flow graphs; VC to detect errors in transformation rules and its conditions; GTG to detect errors on the syntactic level by automatically generating tests based on the grammar; FC to detect errors in the entire transformation process by comparing input and output code; and CRT as a final check by compiling and testing the entire system. Our checks were illustrated with industrial examples of maintenance transformations.. We applied our approach to renovation transformations for Cobol consisting of 230 transformation rules and 80,000 lines of code, and to a database migration involving 110 transformation rules and over 4 million lines of code. We showed how we were able to quickly reduce the number of transformation rules that had to be inspected manually, and how we detected and isolated errors in transformations and large amounts of source code. Furthermore, we automatically generated testcases for the transformation rules, which was feasible and very useful for the individual rules. Not all checks detected errors in the projects, and several false positives were reported. However, using the checks we gained confidence in the applied transformations and were able to control the application to large systems. In conclusion, we have developed an effective lightweight approach for checking mass maintenance transformations at low cost. Related work in the field of program transformations can be found, for example, in [23] , where transformational programming is described. Their primary goal is that of general support for program modifications. This includes the generation of programs from formal specifications, adaptation of programs to particular environments, and program descriptions. However, no methods for checking transformations is given. Taxonomies of program transformations are described in [6] , and in [29] program transformations are classified as translations, i.e. the source and target language are different, or as rephrasings, i.e. source and target language are the same. Both types of program transformations can be found in the area of software maintenance.. An automatable methodology for formally proving the correctness of transformation systems is described, constructed and applied in [32] . This can, of course, only be applied if the semantics of the programming language is available, and, as we argued above, involving semantics in automated maintenance is not very practical.. In [5] a transformation system for Cobol is discussed. They state that their transformations are often little more than a recasting of an algebraic law, which makes it plausible that the transformed code behaves as expected. This is not the case for our transformations: these can be complex and highly customisable.. In [17] a complex migration from PL/IX to C++ was carried out. The target language was generated by semi-automatic transformations. The resulting code was verified by passing it through a set of tests, but they do not report about verifying or checking the transformations itself, which is desired in such projects. Another migration is presented in [31] , where assembler code is converted to equivalent C code using the FermaT system. The transformation engine has a library of proven transformations to preserve or refine the semantics of a program. They report that resulting C code compiled without warnings or errors, but they do not mention whether the results were tested and taken into production, or any other way to check the results. In a more recent article from the same author [30] , another assembler to C migration is discussed. In the article the resulting code was reviewed, examined and undergoing final testing by the customer. So possible errors in the transformations have to be discovered by the customer. Our approach aims at detecting errors as early as possible, especially before delivering code to the customer.

O B I O B I B O O O O O O O O B I B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O B I O O O O B O O O O O O O O O O O O O O O O O O O O O O O B O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O B I B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O B I O O O O O O O O B I B O O O O O O O O O O O O O O O B O O O O O O O O O O B I B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B I B O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O B O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O


A NEW APPROACH TO THE AUTOMATIC WEB ACCESSIBILITY The number of Web pages created in an inaccessible manner is very high, and to convert them to be accessible can be impossible. We present a study of different tools that can help to obtain a total Web Accessibility. With this study, we can see the advantages of the automatic correction and the possibilities that this kind of tools offer. The result of the study shows how the applications adapt the Web pages to both the World Wide Web Consortium HTML grammar and to the Web Content Accessibility Guidelines. With this study we find an automatic way to improve Web Accessibility and to solve the problems that it can offer to the Web pages authors. This way consists of combining two tools. This combination gives us results that allow disabled people to use a system that can convert the entire Web in an accessible way. In this paper we present a study of different tools that can improve the Web Accessibility. With this analysis we try to find a tool, or a combination of tools, that can help the e-integration. The potential of the Web in the integration of disabled people is very high, but in order to exploit it, it is necessary that Web page developers use correct the grammar of the HTML (W3C, 1999b) and the accessibility guidelines (W3C, 1999b) . Both of them are dictated by the World Wide Web Consortium (W3C). In the case of the accessibility, it exists a group of especial interesting, called the World Accessibility Initiative (WAI), inside of the W3C.. The use of the HTML grammar in the Web is very low. The lack of knowledge of this grammar, on the part of the Web page designers, has the origin in the fact that they design to a specific Web browser but these Web browsers are not standard (The Web Standards Project, 2007) . If the use of the correct HTML grammar is very low, the use of the norms developed for disabled people is very poor. A great number of Web designers do not know the special needs of the disabled people.. The purpose of this study is to arrive to a strategy that can allow us to transform Web pages to the W3C and WAI normative. More specifically, the norms we are interesting in are the Web Content Accessibility Guidelines (W3C, 1999b) (WCAG).. These guidelines mark what and how it is correct to present information by the Web. In this paper, we compare two tools that work in this manner.. Accessible Web is a tool that works with WCAG (ACTAW) (Fernández et al., 2007) . This tool works with HTML, XHTML and CSS, and it applies the WCAG guidelines to a Web document.. The other tool that we use in this study is the HTML TIDY project (Dave Raggett, 2003) . This application tries to adapt HTML and XHTML code of the Web page to the correct grammar.. The study compares the tools in two manners. First of all, we concentrate the study on the HTML grammar. Second, we analyze the results under the perspective of the Web Accessibility. With these studies we can try to find a possible way to improve Web Accessibility. We have seen a comparative between two tools that work transforming automatically Web pages. Both of them try to apply the standards of the W3C. HTML TIDY works on the correction of the HTML grammar and ACTAW transforms Web pages to be accessible to disabled people.. The comparative shows us that the tools work correctly outside of its field and have great results on its field. After studying the tools, we have studied the result of their combinations. The results show that the combination of ACTAW and HTML TIDY can offer an improvement of the 73.34% in the correction of the HTML source. If we think in Web Accessibility, the combination can improve a 32.95%. This combination offers a very good improvement of the Web.. In conclusion, we can say that we have found a possible automatic solution to improve Web Accessibility. The combination of different tools can allow us to obtain a way to correct the low index of accessible Web pages.

O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I I B O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O B I O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O


Speech Recognition under Multiple Noise Environment Based on Multi-Mixture HMM and Weight Optimization by the Aspect Model In this paper, we propose an acoustic model that is robust to multiple noise environments, as well as a method for adapting the acoustic model to an environment to improve the model. The model is called "the multi-mixture model," which is based on a mixture of different HMMs each of which is trained using speech under different noise conditions. Speech recognition experiments showed that the proposed model performs better than the conventional multi-condition model. The method for adaptation is based on the aspect model, which is a "mixture-of-mixture" model. To realize adaptation using extremely small amount of adaptation data (i.e., a few seconds), we train a small number of mixture models, which can be interpreted as models for "clusters" of noise environments. Then, the models are mixed using weights, which are determined according to the adaptation data. The experimental results showed that the adaptation based on the aspect model improved the word accuracy in a heavy noise environment and showed no performance deterioration for all noise conditions, while the conventional methods either did not improve the performance or showed both improvement and degradation of recognition performance according to noise conditions. key words: multi-mixture HMM, noise-independent acoustic model, aspect model, speech recognition in noisy environment Background noise has always posed a serious problem in speech recognition systems.. Many methods have been proposed for solving background noise problems [1] ; these methods can be classified into three types: recording-based [2] - [4] , analysis-based [5] - [8] , and modelbased methods [9] - [11] . The recording-based method utilizes multiple input signals, such as signals from a microphone array, to emphasize speech signals. These emphasized signals are used as the input for the hidden Markov model (HMM). The analysis-based method utilizes a special representation of speech signals that is robust against additive noises. The spectral subtraction method [5] and the perceptual linear predictive analysis [6] are the widely used algorithms belonging to this category. The model-based method utilizes the HMM that is not trained with clean speech, but is directly trained with a mixture of speech and environmental noise signals. The recording-, analysis-, and model-based methods for noise-robust speech recognition are complementary; these three methods can be combined together for improving the robustness in a noisy environment [12] - [14] .. In this study, we focus on the model-based method for noise-robust speech recognition in various noise environments. A multi-condition HMM (MC-HMM) can be used in the model-based approach [11] . This method trains an HMM using training data that contains speech signals corrupted by various environmental noises. The trained HMM is known to be robust against various types of noises used in the training [11] . However, the recognition accuracy of the MC-HMM is not as high as that of an HMM trained using speech signals in the matched noise environment.. A noise adaptation technique, which tunes an HMM to recognize speech in a specific noise environment using small amount of data obtained in the target environment, is effective in solving this problem. The maximum likelihood linear regression (MLLR) [16] , a famous algorithm used for speaker adaptation, can be easily applied for noise adaptation. Although a combination of the MC-HMM and the MLLR is effective for speech recognition in noisy environments, it requires a large amount of adaptation data (more than 10 sentences) for achieving sufficient performance [18] . Another noise adaptation approach is based on tree-structured clustering method [21] . In this method, treestructured clustering [17] is performed on various noise and signal-to-noise ratio (SNR) conditions. Then, based on the ML criterion, the HMM that best matches the input speech was selected by tracing the tree from top to bottom. Furthermore, MLLR adaptation is performed using the selected HMM to reduce mismatches with the input speech.. In this paper, we propose a new acoustic model called a multi-mixture HMM (MM-HMM), and its adaptation technique, termed as an aspect model, for speech recognition in noisy environments. These models have high recognition accuracy even when a very small amount (around 1 s) of observed data are used. This paper is organized as follows. In Sect. 2, we introduce the MM-HMM, which improves the performance of MC-HMM. In Sect. 3, we provide an overview of the aspect model approach and discuss the potential of the technique Copyright c 2010 The Institute of Electronics, Information and Communication Engineers using the aspect model. In this paper, we proposed an acoustic model that is robust to various environmental noises. The MM-HMM was obtained by combining HMMs that are trained using corrupted speech data each containing different types of background noises. Experimental results showed that the MM-HMM exhibited the best recognition performance for any type of noise and any variation in SNRs. On the basis of the MM-HMM, we investigated the noise-robust speech recognition method using an adaptation approach. The aspect model is a two-level mixture model, which can reduce the number of free parameters for adaptation.. We evaluated the performance of the proposed method through an experiment. Although we used noisy speech data of very short length, the performance of the proposed method was higher than that of MM-HMMs under heavy noise condition. In addition, we compared the proposed method with the EM-based weight optimization and the model selection method based on a tree-structured model clusters. As a result, the proposed method outperformed the existing adaptation methods except the model selection method at 0 dB SNR condition. Moreover, the proposed method improved the recognition performance constantly regardless of the SNR conditions. In order to confirm the effectiveness of the MM-HMMs, several speech recognition experiments were carried out. The recognition performance of MM-HMMs, clean HMMs and MC-HMMs was compared. Seventeen types of background noises shown in Table 1 were used for the experiments. Twelve noises were used as training data, and the other five noises were used as test data. Note that the noise "Exhibition hall" and "Crowded street" are involved in both of the training and test data; however, these noise signals were recorded at different places. Therefore, we regard these noise signals as belonging to different environments.. The training signals were generated by combining clean speech signals and noise signals with four SNR, 5, 10, 15 and 20 dB. The test signals were generated similarly, with SNR conditions of 0, 5, 10, 15, 20, 25 and 30 dB. The clean speech signals were also used as test data.. All single-noise HMMs and MC-HMM consisted of tied-state triphones. The structure of tied states was automatically determined by the decision tree method, and the structures of all HMMs were determined separately. A state in the MM-HMM is constructed by combining the states in the single-noise HMMs. When combining the Gaussian mixture, a uniform distribution is used (i.e., γ j = 1/N). 13-dimensional Mel-frequency cepstral coefficient (MFCCs) feature vectors excluding the frame log power were extracted from the pre-emphasized speech signal every 10 ms using a 25 ms Hamming window. The MFCCs and ΔMFCCs were concatenated to form 25-dimensional feature vectors. Cepstral mean normalization was used. The performance was evaluated using word accuracy. The other experimental conditions are shown in Table 2 .. The speech recognition experiments for various SNR conditions were carried out. The MM-HMM was constructed from 48 single-noise HMMs (12 noise variations × 4 SNR variations), with each state having 768 (16 × 12 × 4) mixtures. The MC-HMMs were trained using all available training samples. In the test data, SNR was set to 0, 5, 10, 15, 20, 25, 30, and ∞ dB. Figure 1 shows the experimental results. In the figures, "MM" denotes "MM-HMM"; "clean", "clean HMM"; "MC", "MC-HMM", and the number after "m", the number of mixtures. These results show that the MM-HMM has the highest accuracy for all SNRs. Among the MC-HMMs, the best result was obtained when the number of mixture was 16, showing that it was difficult to train all variations from noisy environments, speakers, and other fluctuations altogether using the EM algorithm..

O O O O O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I B I I B I B I I I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Quality documentation and records management: a survey of Turkish universities Purpose -The purpose of this paper is to assess the records system of a Turkish public university, using the example of Hacettepe University in order to develop records management programs in Turkish universities. Design/methodology/approach -A survey method is used in this research; data are gathered through literature reviews, legal analysis, questionnaires, and interviews. Analyzing the information gathered concerning the differences and commonalities of the systems will allow researchers to develop solutions for records management. Findings -The paper finds that institutional processes in Turkish public universities relating to records are not able to meet legal and administrative requirements, and this inadequacy resulted from erroneous applications, insufficient legal regulations, lack of quality-based administrative structure, ineffective records management systems, and unqualified staff. Originality/value -This paper uses analysis techniques specific to the records management and quality management fields in order to provide information about the administrative systems needed for quality-based systems documentation. One of the fundamental aims of organizations nowadays is to achieve "quality." Designing a road map to attain quality requires considering the concept as a whole: developing policies, procedures, and practices which include every institutional component; transforming these into written documents; and implementing, evaluating, and controlling the system in accordance with these documents. While the documents prepared in light of outside standards and institutional needs illuminate the institution's future, records illuminate the institution's past. To achieve institutional quality, both preparing documentation about administrative systems and also implementing a records management program are extremely important. Analyzing the administrative and legal systems of institutions is the first step toward developing the document and records programs fundamental for designing quality-based systems (Brumm, 1996; Schlickman, 2003) . Therefore, this paper aims to prepare quality system documentation requirements for the records system of Hacettepe University, a well-known Turkish university and a leader among Turkish public universities with regard to scientific publications in social science citation index, science citation index , and arts and humanities citation index (Academic Ranking of World Universities, 2006) .

O O O B I O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B I O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O B O O


An efficient optimization scheme for WDM/TDM PON network planning With the growing popularity of bandwidth demanding services such as HDTV, VoD, and video conferencing applications, there is an increasing demand on broadband access. To meet this demand, the access networks are evolving from the traditional DSL (xDSL more recently) and cable techniques to a new generation of fiber-based access techniques. While EPONs and GPONs have been the most studied passive optical access networks (PONs), WDM-PON is now clearly seen as the next generation trend with an hybrid set of switching equipment.We propose here an original optimization scheme for the deployment of greenfield PON networks where we minimize the overall deployment cost. Given the geographical location of ONUs and their incoming/outgoing traffic demands, the newly proposed scheme optimizes the placement of splitters/AWGs in a PON and the link dimensioning in order to provision the overall demand.The optimization scheme proceeds in three phases. In the first phase, we generate several potential equipment hierarchies, where each equipment hierarchy is associated with an ONU partition such that a switching equipment is associated with each cluster, each ONU belongs to a single cluster, and the splitting ratio of the equipment corresponds to the number of ONUs in the cluster. In the second phase, for each equipment hierarchy, we make use of a column generation (CG) mathematical model to select the type and location of the switching equipment that leads to the minimum cost multi-stage equipment topology which accommodates all the traffic demand. The third phase selects the best hierarchy among all the generated and dimensionedOctober 2, 2012hierarchies. The optimization model encompasses the particular cases where all switching equipment are either splitters and AWGs, and outputs the location of the switching equipment together with the dimensioning of the PON network. We performed numerical experiments on various data sets in order to evaluate the performance of the optimization model, and to analyze the type of equipment hierarchies which are generated depending on the traffic and the location of the ONUs. The Internet has enjoyed rapid growth in users and applications since the early 1990s, and while the driving factors have evolved from emails to web browsing to a nowadays continued surge in mobile-ready devices such as tablets, smart phones, and widespread mobile video content consumption, Internet goes on enjoying a steady growth. As an ultimate broadband access solution for future Internet, passive optical networks (PONs) bring many advantages such as cost-effectiveness, energy savings, service transparency, and signal security over other last/first-mile technologies.. The basic architecture of a PON consists of an optical line terminal (OLT) at the CO (Central Office), a number of optical network units (ONUs), one or multiple passive remote terminals (RTs) splitting optical power from one fiber into multiple fibers and vice versa, placed in between the OLT and the ONUs. The ONUs are located either at end user premises resulting in FTTPC/FTTH/FTTB (Fiber-to-the-PC/Home/Building) solutions or at the curb site in case of a FTTC (Fiber-to-the-Curb) architecture, see Figure 1 for an illustration.. In a traditional PON, the high capacity of an optical fiber is mingled with the low installation cost of a passive infrastructure by running a single fiber from the OLT to the RT which feeds individual short length fibers to all the ONUs in a neighborhood. As the common feeder fiber part of a PON is shared by all the ONUs, an appropriate channel access mechanism is required in the upstream direction in order to multiplex the traffic streams generated by the ONUs onto the common fiber in a collision-free way [1] . PONs are usually built following either time sharing principle known as time division [2] .. In a TDM-PON, a single wavelength channel is used along the downstream direction for broadcasting the same signal from the OLT to all ONUs by utilizing a passive optical power splitter or a cascade of passive splitters as the RT and another dedicated channel is used along the upstream direction for multiplexing signals from different ONUs in the time domain toward the OLT.. Although TDM PONs provide higher bandwidth than copper wire based access technologies, it is not anymore enough in view of the still increasing bandwidth demands, especially with applications such as video on demand or online gaming. Indeed, TDM-PON architectures are bandwidth limited as a single wavelength is shared among the PON set of users, resulting in a reduction of the average bandwidth per user to a few tens of megabits per second [3] . The end users' demand for more bandwidth can be satisfactorily mitigated by employing WDM-PON technology without drastically changing the fiber infrastructure. WDM-PONs support multiple wavelengths in either or both upstream and downstream directions by using a passive WDM coupler/arrayed waveguide grating (AWG) router as the RT.. A simple WDM PON architecture requires expensive WDM components such as dedicated transceiver per user at the OLT and optical source at each ONU. To reduce the cost of WDM-PON technology, several technologies have been proposed and demonstrated by both academia and industry. There are mainly two approaches [4] . The first one is the remodulation method of the downlink signal at each ONU such as using saturated semiconductor optical amplifier (SOA) [5] [6] , injection-locked Fabry-Perot laser diode (F-P LD) [7] , mutually injected F-P LD [8] . The second approach is the controlling of the wavelength source in the CO rather than in the ONUs by using additional devices in CO or each ONU for the up-link wavelength source such as employing spectrum sliced light-emitting diode (LED) [9] , spectrum sliced LED with cyclic AWG [10] , spectrum-sliced amplified spontaneous emission(ASE) of erbium-doped fiber amplifier(EDFA) [11] , ASE injection locked F-P LD [12] , and the wavelength-seeded reflective SOA(RSOA) [13] .. More recently, hybrid WDM/TDM PON networks (also called TWDM-PON networks) have been proposed in order to take into account the advantages of power splitting in TDM-PON and wavelength routing in WDM-PON, see, e.g., [14, 15] .. In this paper, we investigate the network dimensioning and the placement of switching equipment in a hybrid WDM/TDM PON network in which, in order to increase the number of subscribers, we both consider splitters and AWGs. The paper is organized as follows. In Section 2, we review the recent studies related to a PON network planning and the placement of switching equipment in a PON network. Our proposed optimization process is described in Section 3. Section 4 describes the first phase of the optimization process, i.e., the clustering algorithm. Phase II, which relies on the solution of a column generation model for selecting the location of the equipment and performing the network dimensioning, is presented in Section 5. The solution of the column generation model is described in Section 6. Section 7 discusses the numerical experiments which have been conducted on various data sets. Conclusions and future work are drawn in the last section. We have proposed an automated tool to find the provisioning of the unicast/multicast demand in a WDM/TDM PON network, while optimizing the location of the passive switching equipment assuming it can either be made of splitters or AWGs. As shown in the section on numerical results, the tool is quite powerful as data instances with up to 128 ONUs can be easily solved.. In the near future, we will look at expanding those tools in order to identify the best set of WDM/TDM PONs for a given geographical area, i.e., finding the optimal location of the switching equipment for each PON, as well as the provisioning of the unicast/multicast traffic.

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Social media analytics: a survey of techniques, tools and platforms Abstract This paper is written for (social science) researchers seeking to analyze the wealth of social media now available. It presents a comprehensive review of software tools for social networking media, wikis, really simple syndication feeds, blogs, newsgroups, chat and news feeds. For completeness, it also includes introductions to social media scraping, storage, data cleaning and sentiment analysis. Although principally a review, the paper also provides a methodology and a critique of social media tools. Analyzing social media, in particular Twitter feeds for sentiment analysis, has become a major research and business activity due to the availability of web-based application programming interfaces (APIs) provided by Twitter, Facebook and News services. This has led to an 'explosion' of data services, software tools for scraping and analysis and social media analytics platforms. It is also a research area undergoing rapid change and evolution due to commercial pressures and the potential for using social media data for computational (social science) research. Using a simple taxonomy, this paper provides a review of leading software tools and how to use them to scrape, cleanse and analyze the spectrum of social media. In addition, it discussed the requirement of an experimental computational environment for social media research and presents as an illustration the system architecture of a social media (analytics) platform built by University College London. The principal contribution of this paper is to provide an overview (including code fragments) for scientists seeking to utilize social media scraping and analytics either in their research or business. The data retrieval techniques that are presented in this paper are valid at the time of writing this paper (June 2014), but they are subject to change since social media data scraping APIs are rapidly changing. Social media is defined as web-based and mobile-based Internet applications that allow the creation, access and exchange of user-generated content that is ubiquitously accessible (Kaplan and Haenlein 2010) . Besides social networking media (e.g., Twitter and Facebook), for convenience, we will also use the term 'social media' to encompass really simple syndication (RSS) feeds, blogs, wikis and news, all typically yielding unstructured text and accessible through the web. Social media is especially important for research into computational social science that investigates questions (Lazer et al. 2009 ) using quantitative techniques (e.g., computational statistics, machine learning and complexity) and so-called big data for data mining and simulation modeling (Cioffi-Revilla 2010) .. This has led to numerous data services, tools and analytics platforms. However, this easy availability of social media data for academic research may change significantly due to commercial pressures. In addition, as discussed in Sect. 2, the tools available to researchers are far from ideal. They either give superficial access to the raw data or (for non-superficial access) require researchers to program analytics in a language such as Java. As discussed, the easy availability of APIs provided by Twitter, Facebook and News services has led to an 'explosion' of data services and software tools for scraping and sentiment analysis, and social media analytics platforms. This paper surveys some of the social media software tools, and for completeness introduced social media scraping, data cleaning and sentiment analysis. Perhaps, the biggest concern is that companies are increasingly restricting access to their data to monetize their content. It is important that researchers have access to computational environments and especially 'big' social media data for experimentation. Otherwise, computational social science could become the exclusive domain of major companies, government agencies and a privileged set of academic researchers presiding over private data from which they produce papers that cannot be critiqued or replicated. Arguably what is required are public-domain computational environments and data facilities for quantitative social science, which can be accessed by researchers via a cloud-based facility. Research requirements can be grouped into: data, analytics and facilities.

B I O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I B O O O O B I O O O O O O O O O O O O O O B I O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O B I O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B I B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O B O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O B I O B I O O O O O O O O B I O O O O O O B I B O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


A distributed virtual MIMO coalition formation framework for energy efficient wireless networks In this paper, we consider a distributed virtual multiple-input multiple-output (MIMO) coalition formation algorithm. Energy savings are obtained in the reverse link by forming multi-antenna virtual arrays for information transmission. Virtual arrays are formed by finding a stable match between two sets of single antenna devices such as mobile stations (MSs) and relay stations (RSs) based on a game theoretic approach derived from the concept of the college admissions problem. Thus, power savings are obtained through multi-antenna arrays by implementing the concepts of spatial diversity and spatial multiplexing for reverse link transmission. We focus on optimizing the overall consumed power rather than the transmitted power of MSs and RSs. Furthermore, it is shown analytically and by simulation that when the overall consumed power is considered, the energy efficiency of the single antennas devices is not always improved by forming a virtual MIMO array. Hence, single antenna devices may prefer to transmit on their own when channel conditions are favorable. In addition, the simulation results show that the framework we propose provides comparable energy savings and a lower implementation complexity when compared to a centralized exhaustive search approach. Energy consumption has become a major research topic due to the growing energy costs which comes along with the global increase in the number of mobile subscribers. On one hand, the data volume of communication networks is expected to grow by a factor of 10 every 5 years, which brings a doubling of energy consumption over the same time period [1, 2] . On the other hand, mobile stations' (MSs) capabilities and operation time are mostly constrained due to their limited battery resources. Most of the power expenditure of MSs in transmission mode is due to the power amplifiers and the signal processing module [3] . Thus, effective solutions allowing MSs to maximize their battery life while optimizing the overall power expenditure rather than only the transmit power are an open research field [1, [4] [5] [6] .. The use of multiple antennas in wireless links has emerged as an effective way to reduce the power con-*Correspondence: rodrigo.vaca@cns.gob.mx 1 Scientific Division, Federal Police, 01110, Constituyentes 947, Mexico City, Mexico Full list of author information is available at the end of the article sumption in the reverse link. It has been shown in [7] that multi-antenna systems require less transmitted power to achieve the same capacity requirements than single antenna devices. In Long-Term Evolution (LTE), a base station (BS) may support multiple antennas. However, MSs may not be equipped with more than one single antenna due to physical constraints [8, 9] . Hence, implementing effective solutions allowing MSs to benefit from the advantages of multi-antenna systems without the extra burden of having multiple antennas physically present at the users' side has become a major issue for current communication systems.. Cooperative communications have recently attracted significant attention as an effective way to improve the performance of wireless networks [10, 11] . By the use of cooperative techniques, wireless devices are allowed to share and use the network resources in a more efficient way [6, 10, [12] [13] [14] [15] [16] . As an example, the authors in [14] present a cooperative method to share the network resources and manage interference among femtocells in a distributed manner. Hence, femtocells form coalitions to improve their performance by sharing spectral resources and maximizing the spatial reuse. In [16] , the authors consider the consequences that arise when two multi-antenna systems share the same spectrum band. They demonstrate that if cooperation between the two systems is possible, they may achieve a performance close to the maximum sum-rate.. An important application of cooperative techniques is the formation of virtual multi-antenna arrays. In this context, a number of single antenna devices may cooperate with each other by forming virtual multiple-input multiple-output (MIMO) transmitters or receivers to reap some of the benefits of multi-antenna systems [17] . The theoretical aspects of virtual MIMO have previously been covered in [17, 18] . Work on virtual MIMO which considers energy efficiency as an optimization metric can be found in [8, 12, 19] . The authors in [12, 19] illustrate the energy savings obtained when virtual MIMO techniques are used compared with non-cooperative approaches in wireless sensor networks. They argue that at certain ranges from the destination node, cooperative MIMO results in a more energy efficient solution that also reduces the total delay compared with the noncooperative case. In [8] , an approach to optimize the power allocation between transmitter and relay in order to minimize the overall energy per bit consumption is presented. Moreover, it is shown that by using an optimal power allocation, the virtual MIMO case achieves an energy efficiency performance close to the ideal MIMO system.. As mentioned previously, most of the current research in energy efficient virtual MIMO tackles the problem of 'why to cooperate. ' Nevertheless, there are two questions that remain unanswered, namely 'when to cooperate' and 'with whom to cooperate. ' In this work, we aim to provide an answer for both questions by providing a coalition formation framework that allows single antenna devices to decide with whom to cooperate in order to obtain energy savings in the reverse link transmission.. In addition, the implementation of cooperative solutions may face many challenges due to the large scale nature of wireless systems. Cooperation comes along with costs such as power expenditure that may limit or reduce the system's performance. Moreover, if cooperation between the users is regulated by a centralized entity, a significant amount of wireless signaling overhead is required between the users and the network. Furthermore, it is well known that the use of centralized techniques entails extra implementation costs and an increase in system's complexity [1, 20, 21] . Thus, the design of effective techniques that allow the single antenna devices to autonomously decide when and with whom to cooperate with the aim of obtaining power savings in the reverse link is a matter of vital importance in communication systems [22, 23] . In this regard, game theory provides a powerful mathematical tool for the design of distributed solutions in cooperative communications [5, 10, 13, 22] . Through the use of coalitional game theory, the authors in [22] propose a merge and split distributed algorithm to form multi-antenna coalitions among single antenna devices. The aim of their work is to maximize the users' rate while accounting for the cost of cooperation in terms of power. The main difference between the merge and split scheme and our proposal is that splitting may involve finding all the possible partitions of the set formed by the users in a coalition, which increases significantly the complexity of the method when compared to the scheme presented in this paper. The authors in [24] propose a relay selection method to improve the spatial diversity in the system by using the concept of amplify and forward. They model the cooperation in wireless networks as a Stackelberg game. Moreover, they consider as optimization parameters the transmitted power and the user rate. The proposal is quite novel and interesting; however, they take into account the transmitted power rather than the overall power consumption. In addition, the communication overhead and the complexity of the method due to the use of the Stackelberg game may add an extra limitation to the system. In [5] , we propose an energyefficient solution for virtual MIMO coalition formation, where cooperation is modeled as a game theoretical approach derived for the concept of stable marriage with incomplete lists. An optimal relay is selected to jointly minimize the reverse link power expenditure. Furthermore, we show that the communication overhead may be significantly reduced by using distributed techniques. Nevertheless, a major drawback of the framework proposed in [5] is that the number of elements able to join the coalition is constrained to a limited number, typically two.. The main contributions of this paper are as follows: (1) to provide a distributed low-complexity virtual MIMO coalition formation algorithm to reduce the energy consumption in the reverse link; (2) our solution can support any number of transmitters participating in the coalitions; (3) we focus on enhancing the MS performance by forming virtual coalitions with the relay stations (RSs). Moreover, we optimize the overall power consumption of MSs and RSs for reverse link transmission; (4) we analyze our proposal from both diversity and capacity perspectives; and (5) our proposal focuses on reducing the overall device consumed power rather than the transmitter radio frequency (RF) power, thus we take into account the power consumption of the RF components such as the power amplifiers and the baseband (BB) module.. The rest of the paper is structured as follows: Section 2 describes the problem scenario, Section 3 presents our power consumption model and performance measures. In Section 4, our cooperative framework is shown. Moreover, in Section 5, we present a theoretical analysis of the consequences arising when optimizing the overall consumed power rather than the transmitted power when implementing spatial diversity and spatial multiplexing in multi-antenna systems. A summary of the comparison schemes and our simulation scenario is described in Section 6. Simulation results are presented in Section 7. Finally, Section 8 offers concluding remarks. From Figures 5 and 7 , it is easy to see that increasing the number of antennas provides power savings at all percentiles of the CDF when only the transmitted power is optimized. However, this trend does not remain the same when optimizing circuit power consumption. In Figure 6 , in the case of diversity, we see that the SIMO curve intersects the MIMO curves when transmitting with three and six antennas at the 30th and 45th percentile, respectively. Moreover, for the capacity case in Figure 8 , we see that the SIMO curve intersects the MIMO curves when transmitting with three and six antennas at the 20th and 28th percentile, respectively. This intersection point represents that in the diversity case, SIMO is more power efficient for 30% and 45% of the users in the cell when compared to MIMO when transmitting with three and six antennas, respectively. The same relation holds for the spatial multiplexing case. This is because the MSs are able to experience better transmission conditions, when they are close to the BS. Thus, turning on the RF transmitter and the BB module of the relay stations is less power efficient than transmitting with only one antenna. Nevertheless, as the users get close to the cell edge increasing the number of transmit antennas tends to be an energy efficient solution when circuit power consumption is optimized. This fact can be seen from Figures 6 and 8 , since as the number of antennas increases, it allows the three and six antennas curves to converge faster to the tail of the distribution. Our analysis in this section will be useful to understand the performance of our framework proposed in Section 7. From the simulations, we generate the CDFs and the graphs that illustrate the performance in terms of overall power expenditure for the schemes presented in Section 6.. When diversity is enhanced in Figure 9 , we show the overall consumed power at different distances from the BS, where all the users in the cell aim to achieve the same target SNR. We observe that the distributed and centralized approaches exhibit a similar performance when compared to the baseline method at close distances from the BS (up to 75 m). This is because as mentioned in the analysis presented in Section 5.1, MSs experience good transmission conditions close to the cell center. Thus, turning on the BB and the RF module of the RSs becomes less power efficient than transmitting with only one antenna. Conversely, when channel conditions are no longer so beneficial (e.g., after 75 m), we see that as the MSs move away from the BS, the increase from one to a higher number of transmit antennas allows the MS to obtain potential energy savings. Furthermore, from the analysis shown in Section 5.1 and the results presented in Figure 9 , we can confirm that, when circuit power consumption is optimized and spatial diversity is enhanced, by increasing the number of antennas, the obtained power savings are more visible at the cell edge than at the cell center. In Figure 10 , we evaluate the system energy efficiency, given by Equation 28 . Notice that at the 50th percentile the CAF scheme is more energy efficient compared to the benchmark, the MRH path loss, the BW channel, and the SMI framework with improvements of 58%, 15%, 10%, and 5%, respectively. Nevertheless, the CAF scheme has losses of 10% compared to the centralized global optimum scheme. These losses are tolerable in practice due to the significant reductions in complexity for the CAF method compared to the centralized optimum scheme: this is discussed further at the end of this section. Moreover, the better performance in energy-efficiency terms for the CAF and the centralized optimum when compared to the other distributed approaches can be easily understood as a direct consequence of the bigger number of antenna elements than can be involved in the coalition.. When spatial multiplexing is used, we aim to obtain gains in energy efficiency by dividing the total data rate requirements between the elements forming the virtual MIMO link. Thereby, as in the diversity case, we can see from Figure 11 that most of the power savings due to coalition formation are observed at the cell border. This is because, it is more power efficient to deliver high transmission rates for SIMO users close to the BS than when close to the cell edge due to the improved propagation conditions. Thus, using a lower modulation order for transmitting from each antenna in a coalition when close to the cell edge becomes more power efficient than using a single transmitter. Hence, from the results obtained in Section 5.2 and Figure 11 , it can be understood that increasing the number of transmit antennas to split the total rate requirement among the transmitters by implementing spatial multiplexing is more power efficient in terms of overall power consumption at the cell border than at the cell center. Finally, in Figure 12 , we show the performance in terms of energy efficiency for the approaches presented in Section 6 when spatial multiplexing is implemented. We find that the centralized global optimum is 2% more energy efficient when contrasted to the CAF. Moreover, when comparing the CAF with the other distributed approaches, we see that the CAF method has improvements of 14%, 9%, 5%, and 91% over the MRH, the BW, the SMI, and the baseline SIMO mode, respectively. Thereby, we can confirm that increasing the number of antennas in order to use a lower modulation order results in an energy efficient solution for the network. To conclude our comparison, the complexity of the centralized global optimum approach is compared with the proposed CAF method. On one hand, for the CAF method, each MS-n in the system has to evaluate each RS in its preferred subset of suitable candidates, S n , by using Equation 29 or 30 depending on whether diversity or capacity are enhanced. Furthermore, each RS-r evaluates its preferred subset S r of RSs by using Equation 32 or 33. Big O notation is used to describe the growth rate of the both schemes. Thus, the system performs arithmetic operations with a complexity of O(|S n | 2 ) and O(|S r | 2 ) when candidate MSs or RS are ranked, respectively, where |.| is defined as the cardinality of the subset. If we assume that R N, the complexity of the candidate ranking process is bounded by the number of RSs in the system rather than by the number of MSs. Thereby, this will allow us to upper bound the complexity of the candidate ranking by O(|S n | 2 ) operations. Moreover, forming the MS's preference list, ι n , Equation 31 requires a sorting operation which induces a complexity of O(|S n |log(|S n |)) operations. Finally, the complexity of the decision-making, Algorithm 1 can be upper bounded by a binary search operation which requires a complexity of O(log(|S n |)) operations. Therefore, the dominant factor which determines the CAF scheme complexity will be the one with the largest exponent, thus the complexity of the method will be upper bounded by O(|S n | 2 ) operations.. On the other hand, the centralized global optimum scheme is based on enumerating all possible alternatives for virtual MIMO coalition formation between the MSn and its preferred subset of candidate RSs, S n . This is done with the purpose of finding the optimal number of transmit antennas that would minimize the overall power consumption in the reverse link. Therefore, to guarantee that a given feasible solution is optimal, the solution should be compared with any other feasible solution. In general, an exhaustive search approach, where the number of elements is discrete, is considered N Pcomplete [39] . A notable characteristic of N P-complete problems is that the required time to solve the problem increases very quickly as the size of the problem grows [39] . To implement the exhaustive search scheme, each MS in the system will evaluate the total number of possible combinations in its preferred subset of candidate RSs, S n . Hence, the total number of possible combinations is computed by for the CAF scheme. Furthermore, Figure 13 shows how the complexity of the system changes for both methods as the number of RSs increases in the system. It can be easily seen that as the number of RSs increases, the computational complexity of the exhaustive search increases exponentially, therefore it may not be a suitable solution to implement in real time systems.

O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O B O O B I O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O B I O O O O O B O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Re-Scheduling of Unit Commitment Based on Customers' Fuzzy Requirements for Power Reliability The development of the electricity market enables us to provide electricity of varied quality and price in order to fulfill power consumers' needs. Such customers choices should influence the process of adjusting power generation and spinning reserve, and, as a result, change the structure of a unit commitment optimization problem (UCP). To build a unit commitment model that considers customer choices, we employ fuzzy variables in this study to better characterize customer requirements and forecasted future power loads. To measure system reliability and determine the schedule of real power generation and spinning reserve, fuzzy Value-at-Risk (VaR) is utilized in building the model, which evaluates the peak values of power demands under given confidence levels. Based on the information obtained using fuzzy VaR, we proposed a heuristic algorithm called local convergence-averse binary particle swarm optimization (LCA-PSO) to solve the UCP. The proposed model and algorithm are used to analyze several test systems. Comparisons between the proposed algorithm and the conventional approaches show that the LCA-PSO performs better in finding the optimal solutions. key words: customer requirements, power supply reliability, fuzzy set theory, fuzzy value-at-risk, particle swarm optimization algorithm, test systems Most previous studies have evaluated power loads forecasted using sufficient historical data. Then, using load prediction, grid corporations assign power generation tasks to each power plant without considering the possibility that power consumers can select different power supplies. The recent expansion of the electricity market enables consumers to purchase electricity of different quality and price according to their own requirements. Recently, Bilinton et al. [1] , Niioka et al. [2] and Bilinton and Zhang [3] investigated consumers' preferences and requirements in the construction of their models.. Nevertheless, the current studies have three primary disadvantages. First, there are many factors that must be simulated or determined in order to find which factors will affect the real power loads. For example, weather, temperature and unexpected emergencies influence power consumption. As a result, power systems suffer from the uncertainty associated with the fact that the real power demands always deviate from forecasts [4] . Consequently, the use of historical information alone cannot predict real future demands. Secondly, in conventional models, the customer requirements for power supply reliability are expressed in real values such as 89.4%, 92.5% and 96.7%, but generally speaking, most power consumers have only intuitive opinions on the required supply reliability. Real values cannot effectively describe imprecise and vague customer requirements. Thirdly, the existing studies assign a single value to the consumers' requirements during different periods of the day. In actuality, the power consumers always have different requirements for different periods. With respect to factories' electricity use, for example, for normal and efficient operation, the power supply reliability during working hours should always be higher than during non-working hours. In this study, the conventional models are improved to mitigate the above shortcomings. The experts' opinions from related fields are taken into consideration to better describe the future power loads. To handle the uncertainty that arises from the use of historical data and expert opinions, it is better to treat the forecasted power loads as variables with imprecise distributions, i.e., fuzzy variables. The power supply reliability is described in fuzzy terms, as "94% is preferred, but it must be higher than 88%", or "the reliability is about 85% to 90%". Such expressions are more acceptable for the power consumers when choosing their electricity supplies. Moreover, in this study, the customers are able to buy electricity of varied reliability for each time-period.. Employing fuzzy set theory, we take the forecasted loads and customers' reliability as fuzzy variables; the daily power demand is divided into 24 time-periods for each day (one hour per unit time). To deal with the fuzzy information, the fuzzy Value-at-Risk (VaR) is used to measure the reliability and determine the power demand and spinning reserve. After establishing the power generation and reserve, we must address a unit commitment problem (UCP) which is commonly a complex, nonlinear, mixed-integer optimization problem [4] - [6] . The conventional objective function is updated here by considering the spinning reserve costs in a fuzzy environment. To handle this UCP, we propose a local convergence-averse binary particle swarm optimization (LCA-PSO), which outperforms existing algorithms.. The remainder of this paper is organized as follows: in Sect. 2, we briefly review previous fuzzy power system problems and introduce some basic background regarding fuzzy variables and fuzzy VaR; Sect. 3 illustrates the proposed model; then, Sect. 4 provides the LCA-PSO as the solution; the model and algorithm are exemplified by some Copyright c 2011 The Institute of Electronics, Information and Communication Engineers test systems in Sect. 5; finally, Sect. 6 summarizes the conclusions. In this study, we have proposed a fuzzy power system model that takes into consideration the customers' requirements. The fuzzy variable is used to more accurately describe the future power load and customers' requirements while the fuzzy Value-at-Risk is employed as a technique to evaluate the power demand and reserve for each period under a given confidence level. The conventional unit commitment model is improved by considering the possibility that the reserve is called. This model can minimize the system cost by considering various constraints and the customers' choices of power supply. To solve the problem, we proposed an LCA-PSO as the solution that has been proved to be most useful and effective by the test systems. Furthermore, comparisons with existing algorithms show that the LCA-PSO has higher performance. In addition, the proposed model can be applied to various engineering reliability control problems.

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O B I B I I B I I B I B I I I B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O


Bioinformatics and biological reality Many bioinformaticians seem to shy away from believing that we can have knowledge about a mind-independent biological reality. This paper attempts to show that this tendency is neither well-founded nor harmless. Even though most bioinformaticians work only with terms and concepts, they cannot altogether disregard the question whether these terms and concepts have any real referents. The paper consists of three parts. Part I clarifies three different positions in the philosophy of science with which it would be good for the philosophical outlook of bioinformaticians to become familiar, and it defends one of them, Karl PopperÕs epistemological realism. Part II discusses a distinction which is necessary for epistemological realism and is of practical importance for bioinformatics, the distinction between the use and mention of terms and concepts. Part III, finally, contains some brief concluding words about realism, both in general and in relation to bioinformatics. Many bioinformaticians seem to shy away, if not from believing that there is a mind-independent biological reality, at least from believing that we can have knowledge about such a reality. The aim of this paper is to try to eliminate this tendency towards epistemological anti-realism. The paper consists of two main parts and a brief concluding part. Part I clarifies three different positions in the philosophy of science with which it would be good for the philosophical outlook of bioinformaticians to become familiar. When they are spelled out in some detail it becomes evident that these positions are mutually exclusive, but when seen only vaguely, the false impression may arise that one can sometimes rely philosophically on one position and sometimes on another. I will label them ''MyrdalÕs Biasism'', ''PopperÕs Epistemological Realism'', and ''VaihingerÕs Fictionalism'', respectively. 1 I will defend PopperÕs position. Part II infuses new blood into the common semantic distinction between the use and mention of terms and concepts; 2 both the red and the white blood corpuscles in this new fluid come from the philosophy of intentionality. The view here defended both underpins the epistemological realism defended in part I, and shows that this realism is not only important for bioinformaticiansÕ philo- sophical self-understanding, but is also sometimes of direct relevance for their ordinary work.

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O B O O O O O O O O O O O O O O O O O O O O