waashk/dblp huggingface dataset:
assigning document identifiers to enhance compressibility of web search engines indexes. granting efficient accesses to the index is a key issue for the performances of web search engines (wse). in order to enhance memory utilization and favor fast query resolution, wses use inverted file (if) indexes where the posting lists are stored as sequences of d_gaps (i.e. differences among successive document identifiers) compressed using variable length encoding methods. this paper describes the use of a lightweight clustering algorithm aimed at assigning the identifiers to documents in a way that minimizes the average values of d_gaps. the simulations performed on a real dataset, i.e. the google contest collection, show that our approach allows to obtain an if index which is, depending on the d_gap encoding chosen, up to 23% smaller than the one built over randomly assigned document identifiers. moreover, we will show, both analytically and empirically, that the complexity of our algorithm is linear in space and time.
on tracker attacks in health grids. the utilisation of grid computing to support healthcare research is becoming increasingly widespread, as is the use of it to support healthcare delivery. furthermore, it seems that the two areas are on an inevitable convergence path as clinical communities in several countries start to investigate how real data stored in electronic patient records can be utilised to facilitate research. the use of it within healthcare gives rise to unique social and ethical challenges; the area of grid computing has given rise to significant novel security challenges; and the anticipated convergence of these two fields will inevitably give a new lease of life to established challenges. in this paper we consider the phenomenon of tracker attacks in this emerging context, and outline a potential approach to addressing the problem.
the pegasus portal: web based grid computing. pegasus is a planning framework for mapping abstract workflows for execution on the grid. this paper presents the implementation of a web-based portal for submitting workflows to the grid using pegasus. the portal also includes components for generating abstract workflows based on a metadata description of the desired data products and application-specific services. we describe our experiences in using this portal for two grid applications. a major contribution of our work is in introducing several components that can be useful for grid portals and hence should be included in grid portal development toolkits.
compiler optimizations for java aglets in distributed data intensive applications. code migration in light of distributed data intensive computing poses interesting compilation issues. in this work, we first define a small extension to the aglet model to allow data distribution. in our aglet program, data is distributed over the network using annotations (this is similar to high performance fortran (hpf) where the programmer specifies data distributions through annotations). we analyze the program using the annotations and use the 'owner computes' rule to determine where a given computation should take place. the compiler then schedules the aglet through the network and also determines the data it should carry during its migration. determining efficient schedule of the aglet and which data to carry during migration poses interesting issues.we propose two strategies to optimize the aglet schedule. the first strategy called take all live data: (tald) attempts to carry all the live definitions of variables from a given node when visited. the second strategy take only needed data (tond) attempts to carry only those definitions whose uses are in the destination node. the goal of the first strategy is to minimize the number of migrations which are expensive due to high serialization overheads the second strategy aims to minimize bandwidth consumption during a migration. this could significantly reduce the communication overhead due to minimal amount of data carried during each migration. we have implemented both the strategies in the jikes compiler from ibm. we have evaluated it on a distributed database application and show benefits of both the strategies on large and small databases. the results show that strategies generated by our compiler analysis reduce the overheads and improve execution time.
grammar based off line generation of disposable credit card numbers. context free grammars present the desirable cryptographic property that it is easy to generate and validate strings from a given grammar, however it is hard to identify a grammar given only the strings generated by it. the algorithm used in the authentication protocol proposed in this paper makes use of context free grammars. this authentication protocol is a perfect candidate for the offline generation and validation of a disposable credit card number. the proposed protocol can be used alone and it does not rely on any other cryptographic protocols like ssl for its security. this paper presents and analyses the protocol with respect to its robustness against malicious attacks.
solving the brachytherapy seed localization problem using geometric and linear programming techniques. we propose a technique to solve the brachytherapy seed localization problem in prostate brachytherapy. our algorithm is based on novel geometric approaches to exploit the special structure of the problem combined with a number of key observations which help us formulate it as an integer program. we solve the equivalent linear program and present a variant of randomized rounding to yield an integral solution to our problem. the algorithm is efficient and performs extremely well in practice. we discuss in detail the underlying theory and performance evaluations based on our implementation.
augmenting descriptive scenario analysis for improvements in human reliability design. it is typical for cycles of iteration to be used to refine the current state of the design of a system so that it more closely meets its requirements. such refinements are in terms of the original requirements specification and any new requirements that have been identified during this process. however, not all defined requirements are equally essential, particularly in high consequence systems where there are issues of dependability. although descriptive methods for scenario analysis can be used to highlight new requirements, it can be difficult to evaluate the impact of these new requirements.in this paper, we exemplify this problem and investigate how numeric methods can be used to highlight the impact of consequences identified by descriptive scenario analysis. an example from the context of human reliability analysis is presented and dependability issues for system design are considered.
performance analysis of small fddi networks. fiber distributed data interface (fddi) networks offer a standardized, high-speed interconnection between components in a distributed computer system. extensive research has been conducted on the performance of fddi networks consisting of hundreds of stations distributed over an area of several hundred square meters. this paper extends the prior work to the case of small networks; for example 10 stations distributed around a single room laboratory. the characteristics for these smaller networks differ in some instances from the behavior of larger networks - these differences can be significant in applications where high performance is demanded from a small fddi based network.
selecting parameters of svm using meta-learning and kernel matrix-based meta-features. the support vector machine (svm) algorithm is sensitive to the choice of parameter settings, which makes it hard to use by non-experts. it has been shown that meta-learning can be used to support the selection of svm parameter values. previous approaches have used general statistical measures as meta-features. here we propose a new set of meta-features that are based on the kernel matrix. we test them on the problem of setting the width of the gaussian kernel for regression problems. we obtain significant improvements in comparison to earlier meta-learning results. we expect that with better support in the selection of parameter values, svm becomes accessible to a wider range of users.
standardising the business vocabulary of standards. in the area of standardisation for inter-organisational business processes, terminology confusion is slowly emerging. the meaning of the concept "standard" is not as clear as many people and organisations seem to assume. this paper looks into the various definitions of a standard and four similarly used concepts: specification, recommendation, framework and pattern. when examining the various definitions, four different definitions types were identified: the item itself; the process of creating the item; the document describing how to create the item; and the process of creating this particular document. furthermore, the standardisation efforts described in this paper for the most cases do not define their business vocabulary, meaning that there is some risk for terminology confusion. the conclusion is that there is a need to perform thorough concepts definitions and conceptual modelling in this area.
evaluating database selection algorithms for distributed search. we investigate algorithms of database selection and evaluate their performance by modelling a distributed search system. the evaluation is done using a 10 gigabyte document collection divided into 857 document databases. we have also investigated various evaluation criteria and put forward a new metrics for evaluating database selection algorithms.
decentralized routing algorithms for automated guided vehicles. automated guided vehicles (agvs) are driverless vehicles that are becoming a popular means for material handling. existing methods for routing agvs are generally based on centralized control. the central controller is potentially a bottleneck of communication and the single point of weakness of the system. moreover, the computational cost required to preplan all agv routes may be too high as to affect the scalability of the solution. our project aims to design and develop decentralized routing strategies for an agv system deployed within a container port. two routing algorithms were developed: row-first and semi-random. the goal is to minimize deadlocks and congestion and maximize throughput. the performance of the algorithms were monitored and compared with each other using a graphics based computer simulator called sim-port.
development of a standard format for ebooks. since an electronic book (ebook) has various advantages over a paper-based book, there is a growing interest in ebooks. ebook industries are using different document formats creating difficulties in the interoperability and interchangeability of ebooks. the u.s. and japan have realized the importance of a standard format for ebooks and developed such standards. recently, korea has also developed a standard format based on xml. the primary goal of this standard is to support the interchangeability of ebooks, reflect the characteristics of the korean publication environment, simplify the creation process, and promote compatibility with other standards. it includes an extension mechanism for various document classes, and supports advanced style control such as vertical writing and multi-column based on xsl.
formal specification of role-based security policies for clinical information systems. many healthcare organizations have transited from their old and disparate business models based on ink and paper to a new, consolidated ones based on electronic patient records. there are significant demands on secure mechanisms for collaboration and data sharing among clinicians, patients and researchers through clinical information systems. in order to fulfil the high demands of data protection in such systems, we believe that access control policies play an important role to reduce the risks to confidentiality, integrity, and availability of medical data. in this paper, we attempt to formally specify access control policies in clinical information systems which are highly dynamic and complex environments. we leverage characteristics of temporal linear first-order logic to cope with dynamic access control policies in clinical information systems.
finding frequent itemsets by transaction mapping. in this paper, we present a novel algorithm for mining complete frequent itemsets. this algorithm is referred to as the tm algorithm from hereon. in this algorithm, we employ the vertical representation of a database. transaction ids of each itemset are mapped and compressed to continuous transaction intervals in a different space thus reducing the number of intersections. when the compression coefficient becomes smaller than the average number of comparisons for intervals intersection, the algorithm switches to transaction id intersection. we have evaluated the algorithm against two popular frequent itemset mining algorithms -- fp-growth and declat using a variety of data sets with short and long frequent patterns. experimental data show that the tm algorithm outperforms these two algorithms.
packageblast: an adaptive multi-policy grid service for biological sequence comparison. in this paper, we propose an adaptive task allocation framework to perform blast searches in a grid environment against sequence database segments. the framework, called packageblast, provides an infrastructure to choose or incorporate task allocation strategies. furthermore, we propose a mechanism to compute grid nodes execution weight, adapting the chosen allocation policy to the current computational power of the nodes. our results present very good speedups and also show that no single allocation strategy is able to achieve the lowest execution times for all scenarios.
proactive resilience through architectural hybridization. in a recent work, we have shown that it is not possible to dependably build any type of distributed f fault or intrusion-tolerant system under the asynchronous model. this result follows from the fact that in an asynchronous environment one cannot guarantee that the system terminates its execution before the occurrence of more than the assumed number of faults.some systems resorted to proactive recovery as a way to address this problem, by attempting to ensure that no more than f faults ever occur: nodes are periodically rejuvenated to remove the effects of faults or malicious attacks. however, asynchronous systems with proactive recovery also suffer from the same problem. in fact, proactive recovery protocols usually require stronger assumptions (e.g., synchrony, security) than the system that is proactively recovered.to solve this contradiction, we work with a hybrid distributed system model. we propose proactive resilience as a new and more resilient approach to proactive recovery, based on architectural hybridization: proactive recovery functions are encapsulated in architectural devices that meet the required stronger assumptions, and have a well-defined interface with the recovered system.we present the proactive resilience model (prm) and describe a design methodology under the prm. this methodology is a way of building systems which guaranteedly do not suffer more than the assumed number of faults, and we use it to derive a distributed intrusion-tolerant secret sharing system.
evaluating the intrinsic dimension of evolving data streams. data streams are fundamental in several data processing applications involving large amount of data generated continuously as a sequence of events. frequently, such events are not stored, so the data is analyzed and queried as they arrive and discarded right away. in many applications these events are represented by a predetermined number of numerical attributes. thus, without loss of generality, we can consider events as elements from a dimensional domain. a sequence of events in a data stream can be characterized by its intrinsic dimension, which in dimensional datasets is usually lower than the embedding dimensionality. as the intrinsic dimension can be used to improve the performance of algorithms handling dimensional data (specially query optimization) measuring it is relevant to improve data streams processing and analysis as well. moreover, it can also be useful to forecast data behavior. hence, we present an algorithm able to measure the intrinsic dimension of a data stream on the fly, following its continuously changing behavior. we also present experimental studies, using both real and synthetic data streams, showing that the results on well-understood datasets closely follow what is expected from the known behavior of the data.
a solution for the location problem in arbitrary computer networks using generic dominating sets. many problems exist related to the location problems of resources in a computer network to accommodate client demands subject to constraints imposed on the clients and the servers. for example, one classical location problem consists of computing the dominating sets (ds) of a network. a ds is a set of nodes in the network (called dominating nodes) such that the remaining nodes in the network are adjacent to at least one dominating node. the problem of finding a ds of minimum cardinality is known to be np-complete. a variety of conditions may be imposed on the dominating set d in a graph g = (v, e). among them, we have multiple domination and distance domination. multiple domination requires that each vertex in v --- d be dominated by at least k vertices in d for a fixed positive integer k. distance domination requires that each vertex in v --- d be within distance r of at least one vertex in d for a fixed positive integer r. we refer to the problem of computing ds when these two conditions are taken into account as the generic dominating sets (gds) problem. prior work on solving the gds problem focuses on interval graphs (ig), which can represent only a few network topologies. we present the first solutions to the gds problem for arbitrary graphs. simulation results regarding several configurations are presented.
dynamic instantiation-checking components. parameterization is an effective technique for building flexible, reusable software. when dealing with parameterized components, an important concern is the time at which parameters are bound. many languages provide syntactic support for parameterized components; this mode of parameterization can be called static parameterization. in order to be able to support dynamic reconfiguration, the service facility pattern has been proposed as an enabling technology for dynamic parameterization. however, static parameterization has the advantage of strong type-checking that dynamic parameterization does not. in this paper, we present dyninstacheck --- a tool that automatically instruments dynamically bound parameterized components with run-time checking code that ensures type-safe parameter binding. the source instrumentation is done in a non-intrusive way, using aspect-oriented programming.
discovery of interesting episodes in sequence data. there is considerable body of work on sequence mining of transactional data. most of the related work on point data (not significant intervals) makes several passes over the entire dataset in order to discover frequently occurring (sequential) patterns. but hybrid apriori, proposed in this paper, as the name implies is an apriori-class of mining algorithm in sql and takes a different approach. significant intervals for each event (or device) is computed first and used for detecting frequent event patterns. the advantages of this approach are that the data set is compressed to find significant intervals thereby reducing the size of input used. also, each event/device is processed individually allowing for parallel computation of individual events. then the hybrid apriori algorithm works on the significant intervals using an apriori-style algorithm adapted to intervals. our approach has significant advantages over the traditional mining algorithms in terms of its efficiency, scalability and storage requirements.
supporting transparent model update in distributed case tool integration. model driven architecture (mda) is a software development approach that focuses on models. in order to support mda, a lot of case tools have emerged; each of them provides a different set of modeling services (operations for automating model manipulation). we have proposed an open environment called modelbus, which enables the integration of heterogeneous and distributed case tools. modelbus enables tools to invoke the modeling services provided by other tools. in this paper, we focus on supporting a particular kind of modeling services: services that update models (i.e. they have inout parameters). our contribution is to enable a tool to update models owned by another tool. we propose a parameter passing mechanism that hides the complexity of model update from tools. first, it enables a tool to update models transparently to heterogeneous model representations. second, it enables a tool to update models located in the memory of another remote tool transparently, as if the models were local. third, it ensures the integrity between the updated models and the tool that owns the models.
extending the epc network: the potential of rfid in anti-counterfeiting. the international chamber of commerce estimates that seven percent of the world trade is in counterfeit goods, with the counterfeit market being worth 500 billion usd in 2004. many companies already use overt anti-counterfeiting measures like holograms to confine counterfeiting and product piracy. however, current techniques are not suited for automated tests of product authenticity as required in warehouses, or do not provide the required level of security. in this context, radio frequency identification (rfid) is a promising approach, providing an extensible, flexible and secure measure against counterfeiting. unique product identification numbers together with an infrastructure to seamlessly share rfid-related data over the internet are a basis of efficient track & trace applications. an emerging infrastructure is the epc network, which can be used to provide pedigree information of products and makes plausibility checks possible. in this paper, we propose a solution for products requiring authentication mechanisms that go beyond track & trace. therefore, the evolving epc network should comprehend the functionality to handle tags which support strong cryptography. we suggest extending the upcoming epc network infrastructure with an epc product authentication service. moreover, the development of cost-effective, dedicated authentication devices as well as the belonging standardization is motivated.
a fast program for maximum likelihood-based inference of large phylogenetic trees. the computation of large phylogenetic trees with maximum likelihood is computationally intensive. in previous work we have introduced and implemented algorithmic optimizations in paxml. the program shows run time improvements > 25% over parallel fastdnaml yielding exactly the same results. this paper is focusing on computations of large phylogenetic trees (> 100 organisms) with maximum likelihood. we propose a novel, partially randomized algorithm and new parsimony-based rearrangement heuristics, which are implemented in a sequential and parallel program called raxml.we provide experimental results for real biological data containing 101 up to 1000 sequences and simulated data containing 150 to 500 sequences, which show run time improvements of factor 8 up to 31 over paxml yielding equally good trees in terms of likelihood values and rf distance rates at the same time. finally, we compare the performance of the sequential version of raxml with a greater variety of available ml codes such as fastdnaml, axml and mrbayes. raxml is a freely available open source program.