Semantic overlay network for large-scale spatial information indexing The increased demand for online services of spatial information poses new challenges to the combined filed of Computer Science and Geographic Information Science. Amongst others, these include fast indexing of spatial data in distributed networks. In this paper we propose a novel semantic overlay network for large-scale multi-dimensional spatial information indexing, called SON_LSII, which has a hybrid structure integrating a semantic quad-tree and Chord ring. The SON_LSII is a small world overlay network that achieves a very competitive trade-off between indexing efficiency and maintenance overhead. To create SON_LSII, we use an effective semantic clustering strategy that considers two aspects, i.e., the semantic of spatial information that peer holds in overlay network and physical network performances. Based on SON_LSII, a mapping method is used to reduce the multi-dimensional features into a single dimension and an efficient indexing algorithm is presented to support complex range queries of the spatial information with a massive number of concurrent users. The results from extensive experiments demonstrate that SON_LSII is superior to existing overlay networks in various respects, including scalability, maintenance, rate of indexing hits, indexing logical hops, and adaptability. Thus, the proposed SON_LSII can be used for large-scale spatial information indexing.Published by Elsevier Ltd. In this paper, we proposed an effective semantic clustering strategy and presented the design of a new semantic overlay network (SON_LSII) that enables more powerful large-scale spatial information indexing. The SON_LSII has a hybrid structure that results in our indexing method achieving a very competitive tradeoff between indexing efficiency and maintenance overhead.. We have carried out more experiments over the Internet with massive amounts of actual spatial raster data. However, vector spatial data cannot be directly divided using the method mentioned above since it needs to record the topological relation between the vector spatial objects. As future work, we plan to extend SON_LSII for more practical applications, especially in online services of vector spatial data. It should be noted that we assume that λ i does not change in the above proof. In fact, λ i does change to some extent. Next, we analyze this change from i¼ 1. To further evaluate the performance of our algorithm, we developed a P2P simulator platform for a spatial data application, called PeerSimSD, which is an extension of PeerSim (PeerSim, 2011) . Furthermore, the research study in (Cheng et al., unpublished) achieved the outstanding award of team graduate design in Jiangsu Province, China. To run the protocol sequentially, PeerSimSD uses a queue based on an event driven engine to simulate the environment of Case B in Section 3.3. We use randomly generated data to simulate 10,000 queries of spatial data.

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Cracking a hierarchical chaotic image encryption algorithm based on permutation In year 2000, an efficient hierarchical chaotic image encryption (HCIE) algorithm was proposed, which divides a plain-image of size M×N with T possible value levels into K blocks of the same size and then operates position permutation on two levels: intra-block and inter-block. As a typical position permutation-only encryption algorithm, it has received intensive attention. The present paper analyzes specific security performance of HCIE against ciphertext-only attack and known/chosen-plaintext attack. It is found that only O( log T (M ·N/K) ) known/chosen plain-images are sufficient to achieve a good performance, and the computational complexity is O(M · N · log T (M · N/K) ), which effectively demonstrates that hierarchical permutationonly image encryption algorithms are less secure than normal (i.e., non-hierarchical) ones. Detailed experiment results are given to verify the feasibility of the known-plaintext attack. In addition, it is pointed out that the security of HCIE against ciphertext-only attack was much overestimated. With the increasing transmission speeds of wired/wireless networks and popularization of image capturing devices and cloud storage services, image data are transmitted over open networks more and more frequently. This makes security of image data become more and more important. The public concern of it becomes serious as news about the illegal online leak of personal photos of some celebrities was released. As a chaotic system owns some similar properties as that of modern encryption schemes, it has been intensively studied as an alternative approach for designing secure and efficient encryption schemes [1, 2, 3] . The main idea and principle of applying chaos theory to protecting images can be traced back to 1986 [4] , which demonstrates the stretching effect of a chaotic map on a painting of Henri Poincaré, a founder of modern chaos theory.. The simplest and most efficient method for protecting multimedia data is permuting the positions of their spatial pixels [5] or frequency coefficients [6] . In the literature, some synonyms of permutation, transposition, shuffle, scramble [6] , swap and shift, are used. Security scrutiny on some specific permutation-only encryption algorithms against known/chosen-plaintext attacks were previously developed [7, 8] . In [9] , a ciphertext-only attack on a specially simple permutation-only encryption algorithm was proposed utilizing correlation redundancy remaining in the cipher-image. No matter how the permutation relationships are generated and what the permutation object is, any permutation-only encryption algorithm can always be represented by a permutation relationship matrix, whose entry stores the corresponding permuted location in the ciphertext [10] . The security of permutation-only encryption algorithm relies on its real permutation domain, in which any element in the permutation object can be permuted independently. As for a permutation domain of size M × N with T possible value levels, it is estimated that the required number of known/chosen-plaintexts for an efficient plaintext attack is O( log T (M · N) ), where x denotes the ceiling function. An upper bound of the attack complexity is also derived therein to be O(n · (M · N). 2 ), where n is the number of known/chosen plain-images [10] . In [11] , the computational complexity of the attack is further reduced to O(n · (M · N)) by replacing the set intersection operations of quadratic complexity with linear element access operations. Even so, all kinds of permutation operations are still being used in multimedia protection today [12, 13, 14, 15] .. In [16] , a typical example of permutation-only image encryption algorithms, called HCIE (hierarchical chaotic image encryption), was proposed. Although security perfor-mance of general permutation-only image encryption algorithms against plaintext attack has been quantitatively analyzed, specific security performance of HCIE is still not evaluated. The core of HCIE is a permutation function composed of rotation operations of four directions, originates from an intellectual toy, Rubik's Cube [17] . In [16] , the authors claimed about the security property of HCIE as follows: "By way of collecting some original images and their encryption results or collecting some specified images and their corresponding encryption results, it is still difficult for the cryptanalysts to decrypt an encrypted image correctly because the permutation relationship is different for each image." In this paper, we will demonstrate that the claim on the robustness of HCIE against known/chosenplaintext attack is groundless. Further more, we find that the hierarchical encryption structure suggested in HCIE does not provide any higher security against known/chosenplaintext attack, but actually make the overall security even weaker. In addition, we find the capability of HCIE against ciphertext-only attack was much over-estimated.. The rest of this paper is organized as follows. The algorithm HCIE is briefly introduced in Sec. 2. Detailed cryptanalysis on HCIE is provided in Sec. 3, with some experimental results. The last section concludes the paper. Specific security performance of a typical permutationonly encryption algorithm, called HCIE, against ciphertextonly attack and known/chosen-plaintext attacks has been studied in detail. It is found that the capability of HCIE against the former attack was over-estimated much and hierarchical permutation-only image encryption algorithms such as HCIE are less secure than normal permutation-only ones without using hierarchical encryption structures. This work effectively demonstrates that the size of the real permutation domain of a permutation algorithm should be as large as possible in order to reach the best performance. As permutation operation alone cannot provide high level of security, it should be combined with other value substitution functions.

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


BANDWIDTH EMPIRICAL MODE DECOMPOSITION AND ITS APPLICATION There are some methods to decompose a signal into different components such as: Fourier decomposition and wavelet decomposition. But they have limitations in some aspects. Recently, there is a new signal decomposition algorithm called the Empirical Mode Decomposition (EMD) Algorithm which provides a powerful tool for adaptive multiscale analysis of nonstationary signals. Recent works have demonstrated that EMD has remarkable effect in time series decomposition, but EMD also has several problems such as scale mixture and convergence property. This paper proposes two key points to design Bandwidth EMD to improve on the empirical mode decomposition algorithm. By analyzing the simulated and actual signals, it is confirmed that the Intrinsic Mode Functions (IMFs) obtained by the bandwidth criterion can approach the real components and reflect the intrinsic information of the analyzed signal. In this paper, we use Bandwidth EMD to decompose electricity consumption data into cycles and trend which help us recognize the structure rule of the electricity consumption series. There are several methods to decompose a time series into different cycles and trends. One of the most fundamental methods is the Fourier decomposition, which deem the signals as a linear combination of harmonic components. Although the Fourier transform is valid under extremely general conditions, there are some crucial restrictions of the Fourier spectral analysis: the system must be linear and the data must be strictly periodic or stationary. In recent years, wavelet decomposition has been developing rapidly. But if the mother wavelet is selected, we will have to use it to analyze all the data. Except non-adaptive nature, the problem of the most commonly used wavelet is its leakage generated by the limited of the basic wavelet function, which makes the quantitative definition of the energy-frequencytime distribution difficult.. Empirical mode decomposition, introduced by Huang et al., 1,2 is a method for decomposing complex, multi-component signal into several elementary Intrinsic Mode Functions (IMFs). Differing from Fourier and wavelet analysis which have predefined basis, EMD uses only scale and frequency characters of the original signal. EMD is a local, fully data-driven and self-adaptive analysis approach. Moreover, the combination of the EMD method and the associated Hilbert spectral analysis can offer a powerful method for time frequency analysis. Although it often proved remarkable effect in many applications, such as engineering mechanics, 3 image processing 4, 10 and signal processing, 6,9 EMD method has several drawbacks. Firstly, it lacks a mathematical base which can represent EMD method naturally. Secondly, it is a pity that the criteria, 1, 7, 8, 11 considered so far are all constraints on the amplitude and have nothing to do with the frequency or phase of the IMF so that IMF obtained based on those criteria will have dramatically different frequencies and cause scale mixing problem. The paper improved EMD algorithm based on the two aspects and used updated EMD algorithm to analysis a time sequence about electricity consumption.. In the next section, we introduce the Empirical Mode Algorithm. In the third section, we provide convergent property of EMD and present an example which leads to stop criterion problem. The fourth section contains stop criterion overview of the SD criterion, 3-thresholds criterion, EDT criterion, Damerval criterion and a detailed Bandwidth Stop criterion which includes bandwidth definition, instantaneous frequency estimation and our sifting algorithm. Finally, Bandwidth EMD is used to decompose a simulated series and one electricity consumption series. We analyze the results carefully and compare the results with other criterion. The sixth section concludes the paper. The results of this study are based on EMD algorithm. EMD algorithm is a succinct and valid technique for some engineering application, but the EMD algorithm has two problems: scale mixture and convergence property. We design a new stop criterion-bandwidth criterion which cannot only find the IMFs reflecting the scale and frequency characters of the analyzed time series but also make the IMFs have reasonable meaning. Except that IMFs obtained with bandwidth criterion have slighter scale mixing effect.. The performance of the EMD algorithm is presented in many fields, but it is almost not some application on the economic domain with EMD algorithm. So we use the Bandwidth EMD algorithm to analyze the electricity consumption data, where the decomposition components corresponding to the climate or man activity orderliness are easily selected. From all the sifting above, although we have not used any prior information and have selected a fixed basic function, we find the components have reflected the nature character of the time series. So the results prove that the Bandwidth EMD is a potential tool for applied economics.

O O O O O O O O O O O O O O O O O O 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 O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 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 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


Reliable heterogeneous applications Abstract-This paper explores the notion of computational resiliency to provide reliability in heterogeneous distributed applications. The notion of provides both software fault tolerance and the ability to tolerate information warefare(IW) attacks. This technology seeks to strengthen a military mission, rather than protect its network infrastructure using static defense measures such as network security, intrusion sensors, and firewalls. Even if a failure or attack is successful and never detected, it should be possible to continue information operations and achieve mission objectives.Computational resiliency involves the dynamic use of replicated software structures, guided by mission policy, to achieve reliable operation. However, it goes further to automatically regenerate replication in response to a failure or attack, allowing the level of system reliability to be restored and maintained. Replicated structures can be protected through several techniques such as camouflage, dispersion, and layered security policy. This paper examines a prototype concurrent programming technology to support computational resiliency in a heterogeneous distributed computing environment. The performance of the technology is explored through two example applications.Index Terms-Software reliability, computational resiliency, fault tolerance, distributed computing, information warfare, network security, heterogeneous computing, load balancing I. INTRODUCTION NY system that operates in highly adverse environments, such as battlefield command and control, must be able to operate reliably by tolerating failures and attacks. Many distributed systems have sought to use replication, either in hardware or software, as a mechanism to provide fault-tolerance and recovery. These approaches provide graceful degradation of performance to the point where no further replication is available and then system failure occurs. This is not sufficient to assure information operations in adverse military situations where networked resources may become available dynamically through retasking. Joohan Lee is with the NY system that operates in highly adverse environments, such as battlefield command and control, must be able to operate reliably by tolerating failures and attacks. Many distributed systems have sought to use replication, either in hardware or software, as a mechanism to provide fault-tolerance and recovery. These approaches provide graceful degradation of performance to the point where no further replication is available and then system failure occurs. This is not sufficient to assure information operations in adverse military situations where networked resources may become available dynamically through retasking.. We are investigating an alternative model of distributed computation termed computational resiliency. This model combines real-time attack assessment with process reconfiguration, dispersion, camouflage, on-the-fly replication, and layered security policy to reliably maintain information operations. To visualize how these concepts might operate, consider a distributed application as analogous to an apartment complex inhabited by a new strain of roach (process/thread) 1 .. The roaches are highly resilient: you can stamp on them, spray them, strike them with a broom but you never kill them all or prevent them from their goal of finding food (resources). To foil your eradication efforts, they use several techniques: they are highly mobile moving from one place in the apartment complex (network) to another with speed and agility. They continually replicate to ensure that it is not possible to kill them all. They sense their environment (attack assessment) to obtain clues that mobility is necessary: if a light is turned on, they scurry away in all directions to hide behind cupboards in places of known safety (secure network zones). If a new roach killer is invented they learn from it, and adapt their behavior to compensate. However, this new strain is particularly aggressive and seeks to live in the daylight (wide-area operation): thus it adopts techniques for camouflage as a form of protection and disinformation. To support this model, we have developed an application independent, programming technology that operates in heterogeneous distributed computing environments. The technology can be applied either to an entire application or a small number of selected components that are crucial to reliable operation. It incorporates the notion of resiliency into an application through a novel message-passing library. The library hides the details of the communication protocols required to achieve automatic on-the-fly replication and reconfiguration. It operates on a broad variety of networked architectures that include commercial-of-the-shelf computer systems and networking components, shared-memory multiprocessors and clusters of homogeneous machines. The library distinguishes these architectural differences for the purpose of performance improvement: For example, when communicating within shared memory, pointer copying is used; when communicating within a homogeneous cluster, no byte or machine t ranslations are needed.. Since machines in the environment may have widely different performance and memory characteristics, load balancing techniques are required. These techniques must disperse replicated structures to realize improved reliability. To explore the performance issues associated with these concepts, we have incorporated the technology into two prototype distributed 1 Thanks to Cathy McCullum for providing this analogy. Fault-tolerance and recovery techniques can be implemented in hardware, software, or a comb ination of both. Here we are concerned primarily with software based techniques that can be applied to distributed real-time applications, such as battlefield command and control. Most of the techniques developed to date are based on notion of process replication to provide high levels of system availability [1] . Unfortunately, the use of replication introduces additional problems such as the need to maintain consistency between replicas, detect the failure of a compromised process, and transparently recover system function.. In many client-server style applications, the techniques employed to provide recovery can be divided into two general categories based on passive [2] or active [3] replication. In passive replication [2] , there is a single primary source and all other replicas are maintained purely as backups. Only the primary source receives requests from clients and guarantees the ordering and atomicity of message delivery. Although easy to implement, this method is slow to transfer control to a backup in the event of failure; this can lead to significant degradation in system response. In active replication [3] , all replicas have the same level of control. Any viable replica may receive a message from a client and collectively the replicas maintain message ordering and atomicity. This approach is attractive for real-time systems because it provides a more transparent view of the system to client processes and is relatively fast to transfer control in the event of failure [4] .. To implement replication it is useful to organize processes into groups and provide communication mechanisms between groups. The concept of a process group was first introduced in the V-kernel to express one-to-many communication structures [5] . A group is a set of processes sharing common application semantics, as well as the same group identifier and multicast address. Each group is viewed as a single logical entity hiding its internal structure from other groups. The processes in a group cooperate to provide a single service. In order to maintain and share a consistent process state, the processes use multicast communication primitives that guarantee every process in the group receives the same messages in the same order. The group concept has been extended to many fault-tolerant distributed systems such as Isis [6] , Horus [7] , Transis [8] , Totem [9] , and Ameoba [10] . These systems all allow members of a group to fail thereby providing graceful degradation of performance to the point of system failure. Although not used for fault-tolerance, the process group has also been used widely as a concurrent programming paradigm through libraries such as PVM [11] and MPI [12] .. A useful taxonomy of database recovery techniques for information warfare has been developed by Jajodia [13] . Cold-start recovery involves a complete restart in the event of a severe attack. Warm-start involves non-transparent but automated recovery. Hot-start techniques are by far the more sophisticated and provide transparent recovery. These techniques operate through a combination of implementation techniques that include checkpoints and intelligent analysis of the effects of attack queries [13] . Checkpointing generally requires more time to recover than process groups since it involves restoring previous state information from a stable repository such as hard disk and starting a new process. Checkpointing mechanisms can sometimes be used transparently and a variety of techniques have been developed to reduce the associated overheads [14, 15, 16, 17] .. The use of networks of personal computers, workstations, and symmetric multiprocessors as a computing platform requires load balancing techniques. Computers in a typical network often differ in processor performance and memory characteristics. Many load balancing techniques have been developed for heterogeneous environments [18, 19] . These typically assume that attacks or faults are unlikely and focus on the optimal allocation of resources. Load balancing techniques for efficient allocation of the replicated processes have also been studied in fault tolerant systems [20, 21, 22, 23] . For example, Nieuwenhuis [20] has proposed a static model to derive the mapping of replicated processes. Bannister [22] has presented an algorithm that balances the load o f replicated processes over a homogeneous system and subsequently analyzed the performance of the algorithm. Schatz [23] proposed a model that expresses the reliability of the system in terms of the probability that the system can run an entire task successfully. This model introduces a process allocation algorithm that maximizes the reliability over heterogeneous systems.. The starting point for the work described in this paper is the Scalable Concurrent Programming Library (SCPlib) [24, 25, 26] . This library provides a heterogeneous concurrent programming technology and has been applied to a variety of irregular, large-scale, industrial simulations [27] . The library is portable to a wide range of platforms, from distributed-memory multicomputers to networks of workstations, PC's and multiprocessors. It provides a mobile thread abstraction in which threads may move between processors to accommodate for changes in resource requirements (e.g. processor speed, memory, bandwidth). The communication structure of an application is represented explicitly and can thus be changed transparently as a thread migrates. The library includes a variety of load balancing and granularity control techniques based on thread migration.

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


Chaospy: An open source tool for designing methods of uncertainty quantification The paper describes the philosophy, design, functionality, and usage of the Python software toolbox Chaospy for performing uncertainty quantification via polynomial chaos expansions and Monte Carlo simulation. The paper compares Chaospy to similar packages and demonstrates a stronger focus on defining reusable software building blocks that can easily be assembled to construct new, tailored algorithms for uncertainty quantification. For example, a Chaospy user can in a few lines of high-level computer code define custom distributions, polynomials, integration rules, sampling schemes, and statistical metrics for uncertainty analysis. In addition, the software introduces some novel methodological advances, like a framework for computing Rosenblatt transformations and a new approach for creating polynomial chaos expansions with dependent stochastic variables. We consider a computational science problem in space x and time t where the aim is to quantify the uncertainty in some response Y, computed by a forward model f, which depends on uncertain input parameters Q :. We treat Q as a vector of model parameters, and Y is normally computed as some grid function in space and time. The uncertainty in this problem stems from the parameters Q , which are assumed to have a known joint probability density function p Q . The challenge is that we want to quantify the uncertainty in Y, but nothing is known about its density p Y . The goal is then to either build the density p Y or relevant descriptive properties of Y using the density p Q and the forward model f. For all practical purposes this must be done by a numerical procedure.. In this paper, we focus on two approaches to numerically quantify uncertainty: Monte Carlo simulation and non-intrusive global polynomial chaos expansions. For a review of the former, there is a very useful book by Rubinstein, Reuven and Kroese [1] , while for the latter, we refer to the excellent book by Xiu [2] . Note that other methods for performing uncertainty quantification also exist, such * Corresponding author at: Center for Biomedical Computing, Simula Research Laboratory, P.O. Box 134, Lysaker, Norway.. as perturbation methods, moment equations, and operator based methods. These methods are all discussed in [2] , but are less general and less widely applicable than the two addressed in this paper.. The number of toolboxes available to perform Monte Carlo simulation is vastly larger than the number of toolboxes for nonintrusive polynomial chaos expansion. As far as the authors know, there are only a few viable options for the latter class of methods: The Dakota Project (referred to as Dakota) [3] , the Opus Open Turns library (referred to as Turns) [4] , Uncertenty Quantification Toolkit [5] , and MIT Uncertenty Quantification Library [6] . In this paper we will focus on the former two: Dakota and Turns. Both packages consist of libraries with extensive sets of tools, where Monte Carlo simulation and non-intrusive polynomial chaos expansion are just two tools available among several others.. It is worth noting that both Dakota and Turns can be used from two perspectives: as a user and as a developer. Both packages are open source projects with comprehensive developer manuals. As such, they both allow anyone to extend the software with any functionality one sees fit. However, these extension features are not targeting the common user and require a deeper understanding of both coding practice and the underlying design of the library. In our opinion, the threshold for a common user to extend the library is normally out of reach. Consequently, we are in this paper only considering Dakota and Turns from the point of view of the common user.. Dakota requires the forward model f to be wrapped in a standalone callable executable. The common approach is then to link this executable to the analysis software through a configuration file. The technical steps are somewhat cumbersome, but has their advantage in that already built and installed simulation software can be used without writing a line of code.. Alternative to this direct approach is to interact with an application programming interface (API). This approach requires the user to know how to program in the supported languages, but this also has clear benefits as an interface through a programming language allows for a deeper level of integration between the user's model and the UQ tools. Also, exposing the software's internal components through an API allows a higher detailed control over the tools and how they can be combined in statistical algorithms. This feature is attractive to scientists who would like the possibility to experiment with new or non-standard methods in ways not thought of before. This approach is used by the Turns software (using the languages Python or R) and is supported in Dakota through a library mode (using C++).. For example, consider bootstrapping [7] , a popular method for measuring the stability of any parameter estimation. Neither Dakota nor Turns support bootstrapping directly. However, since Turns exposes some of the inner components to the user, a programmer can combine these to implement a custom bootstrapping technique.. This paper describes a new, third alternative open source software package called Chaospy [8] . Like Dakota and Turns, it is a toolbox for analysing uncertainty using advanced Monte Carlo simulation and non-intrusive polynomial chaos expansions. However, unlike the others, it aims to assist scientists in constructing tailored statistical methods by combining a lot of fundamental and advanced building blocks. Chaospy builds upon the same philosophy as Turns in that it offers flexibility to the user, but takes it significantly further. In Chaospy, it is possible to gain detailed control and add user defined functionality to all of the following: random variable generation, polynomial construction, sampling schemes, numerical integration rules, response evaluation, and point collocation. The software is designed from the ground up in Python to be modular and easy to experiment with. The number of lines of code to achieve a full uncertainty analysis is amazingly low. It is also very easy to compare a range of methods in a given problem. Standard statistical methods are easily accessible through a few lines of R or Pandas [9] code, and one may think of Chaospy as a tool similar to R or Pandas, just tailored to polynomial chaos expansion and Monte Carlo simulation.. Although Chaospy is designed with a large focus on modularity, flexibility, and customization, the toolbox comes with a wide range of pre-defined statistical methods. Within the scope of Monte Carlo sampling and non-intrusive polynomial chaos expansion, Chaospy has a competitive collection of methods, comparable to both Dakota and Turns. It also offers some novel features regarding statistical methods, first and foremostly a flexible framework for defining and handling input distributions, including dependent stochastic variables. Detailed comparisons of features in the three packages appear throughout the paper.. The paper is structured as follows. We start in Section 2 with a quick demonstration of how the software can be used to perform uncertainty quantification in a simple physical problem. Section 3 addresses probability distributions and the theory relevant to perform Monte Carlo simulation. Section 4 concerns non-intrusive polynomial chaos expansions, while conclusions and topics for further work appear in Section 5.

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


Mixed finite elements for electromagnetic analysis The occurrence of spurious solutions is a well-known limitation of the standard nodal finite element method when applied to electromagnetic problems. The two commonly used remedies that are used to address this problem are (i) The addition of a penalty term with the penalty factor based on the local dielectric constant, and which reduces to a Helmholtz form on homogeneous domains (regularized formulation); (ii) A formulation based on a vector and a scalar potential. Both these strategies have some shortcomings. The penalty method does not completely get rid of the spurious modes, and both methods are incapable of predicting singular eigenvalues in non-convex domains. Some non-zero spurious eigenvalues are also predicted by these methods on nonconvex domains. In this work, we develop mixed finite element formulations which predict the eigenfrequencies (including their multiplicities) accurately, even for nonconvex domains. The main feature of the proposed mixed finite element formulation is that no ad-hoc terms are added to the formulation as in the penalty formulation, and the improvement is achieved purely by an appropriate choice of finite element spaces for the different variables. We show that the formulation works even for inhomogeneous domains where 'double noding' is used to enforce the appropriate continuity requirements at an interface. For two-dimensional problems, the shape of the domain can be arbitrary, while for the three-dimensional ones, with our current formulation, only regular domains (which can be nonconvex) can be modeled. Since eigenfrequencies are modeled accurately, these elements also yield accurate results for driven problems. One of the major problems in computational electromagnetics using conventional nodal finite elements has been the occurrence of spurious solutions. In structural mechanics, mesh refinement helps to reduce the errors; however, in the electromagnetics setting, it merely increases the number of spurious modes. Edge elements [1, 2, 3, 4, 5] , which use basis function associated with each edge are widely used to circumvent this difficulty. These elements ensure tangential continuity of the field along an element edge and model the null space of curl operator accurately. They can model both, singularities and inhomogeneous domains. However, they also have their limitations [6, 7] . Since the normal component is discontinuous across element faces even for homogeneous domains, the efficiency is reduced. Another disadvantage is that coupling with structural or thermal variables (where nodal finite elements are used) in multiphysics problems could be difficult.. In order to deal with spurious modes within the framework of the nodal finite element method, a penalty function or regularization method [8, 9, 10, 11, 12, 13, 14] is used, where a term involving the divergence of the electric field is added to the original variational formulation. However, this method does not eliminate spurious modes, and in fact just pushes them towards the higher part of the spectrum; the problems with this method are particularly severe when non-convex and/or inhomogeneous domains are involved. Costabel and Dauge [15] and Otin [11] have proposed a weighted penalty method where a weight is appended to the penalty parameter which tends to zero at a field singularity. An alternative approach is the use of potentials [16, 17, 18] along with the choice of a suitable gauge. Even in this method, a penalty-type term has to be added. The method is quite robust even for inhomogeneous domains. However, because of the presence of the penalty term, it cannot predict the singular eigenvalues on nonconvex domains.. Recent works include using a combination of cubic Hermite splines and quadratic Lagrange interpolations [19] , and a least squares finite element method [20] . The former method can be applied only to regular geometries, while the latter uses nonstandard elements with stabilizing face bubble functions.. In this work, we develop nodal-based mixed finite element formulations for two and three-dimensional problems. The two-dimensional elements yields very accurate approximations of the eigenvalues, including the correct multiplicities. and including singular eigenvalues for non-convex domains. Nonhomogeneous and curved domains can also be modeled with these elements. The three-dimensional elements can currently be applied only to Cartesian geometries (including domains with singularities and inhomogeneous domains); further work is required to extend their capabilities to non-regular geometries. The main feature of the proposed mixed formulation is that no additional terms, such as the penalty terms that are used in regularized or potential-based formulations, are added to the variational formulation, and in addition, there are no parameters that have to be chosen by the user; alternative formulations which a-priori eliminate spurious modes are presented in References [13, 21] . The improvement is achieved simply by using appropriately chosen interpolations for the various fields. The other main feature is that standard C 0 Lagrange interpolations are used for all the fields, and standard Gaussian quadrature is used to compute all the matrices.. The outline of the remainder of the article is as follows. We first briefly review the variational and finite element formulations for the potential method. Next we discuss the variational formulation and interpolations for the proposed mixed finite elements. Finally, we show the high accuracy and robustness of the proposed formulation by comparing the solutions obtained against either analytical or benchmark solutions obtained using existing numerical strategies. Existing nodal finite element methods for electromagnetic problems either use some kind of a penalty or non-standard interpolation functions. A formulation based on potentials works well for convex domains, even in the presence of inhomogeneities, but fails to predict singular eigenvalues in the case of nonconvex domains besides predicting some spurious eigenvalues.. In this work, we show that mixed finite element formulations are capable of yielding accurate solutions for any domain (convex or non-convex), even in the presence of inhomogeneities. The proposed formulation not only yields accurate values for the eigenvalues but even predicts their multiplicity accurately. In contrast to existing formulations, no penalty terms are added to the original variational formulation, and no factors need to be adjusted in order to obtain the results. Thus, there is very strong numerical evidence that the proposed elements (except the A4 element) satisfy the LBB (inf-sup) conditions [27] .. Currently, although the two-dimensional formulation works for arbitrary geometries, the three-dimensional elements work only for regular geometries, but otherwise yield accurate results even in the presence of singularities.

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


Business process management and supply chain collaboration: a critical comparison The link between a firm and supply chain (SC) members has been recognised as one of the key issues for ensuring business success and achieving competitive advantage. Indeed, working across organisational boundaries is required to accomplish effective responses to customers’ needs. Our preliminary research confirmed that there are positive relationships between business process management (BPM), supply chain collaboration (SCC), collaborative advantage and organisational performance. This study is a step further and uses a multiple case design to illuminate the results and gain a greater understanding from extensive discussions about these relationships. By means of semi-structured interviews, the three main issues were identified as: (1) the link between BPM and organisational performance; (2) the link between BPM and SCC; and (3) the contextual factors and benefits achieved from working collaboratively with SC partners. The different scenarios of the link between BPM and SCC were developed in a taxonomy, and the case studies were used to illustrate the experience of intra- and inter-organisational practices in the developing economy of Thailand. The case studies’ results explain in depth that both BPM and SCC are important for improving organisational performance and competitiveness. BPM not only improves organisational performance directly, but also assists with collaborative activities that in turn help to improve internal capabilities. Additionally, the comparisons in issues relating to firm size, industry type, relationship closeness and relationship length were also included in this study. Early definitions of supply chain management (SCM) typically emphasised the management of activities and material flows, whereas more recent SCM definitions have largely focused on managing the supply chain (SC) as one system with clear strategic goals [1] . Hence, there has been a shift towards managing SC members to gain mutual benefits and a concentration on a SC-centric rather than an organisation-centric view. Within a SC, firms need to provide basic management resources, both internally and in relation to their SC partners, to develop main capabilities in relation to SCM execution [2] . Hence, there has been a change of focus from the process function to SC, which has been characterised by specific attention to partnerships, relationships, networks, value creation and value constellations [3] . Collaboration is known as a ''silver bullet'' in many areas of SCM [4, p. 314] , which illustrates the importance many firms place on it. Building relationships between companies rather than working individually can lead to competitive advantage, resulting in organisational performance improvement [5] . Regarding the importance of intra-and inter-organisational relationships, various researchers have recognised that the link between a firm and its SC members is one of the key issues to ensure business success and competitive advantage [6, 7] . Companies that have developed their internal business process with their suppliers and customers are in a better position to produce and distribute their products at a lower cost and satisfy service level requirements [8] . Hence, firms and their SC members working collaboratively by opening communication and sharing resources, risks and rewards should enjoy mutual benefits. For instance, Hsu et al. [6] studied the impact of SCM practices on operations capability and firm performance. The study illustrated the idea that SCM practices mediate the impact of operations capability on organisational performance. Flynn et al. [9] indicated that SC integration (supplier, internal and customer integration) is beneficial to firm performance. Previous studies have also provided an illustration of the relationships between specific paradigms of internal practices [such as lean manufacturing and enterprise resource planning (ERP) systems] and the SC [10, 11] . However, there is a need for a comprehensive study of other aspects that link SC partners in their attempts to achieve competitive advantage and improve organisational performance.. Regarding business process management (BPM) and supply chain collaboration (SCC), prior research has suggested that both BPM and SCC are important for improving performance and competitiveness [11] [12] [13] [14] . For instance, Min et al. [13] developed a model of SCC to demonstrate the relationships between the antecedents of collaboration, collaboration itself and its consequences. The antecedents included strategic intent, internal alignment, relationship orientation, relationship-specific investment, a free flow of information and heightened communication and formalisation. Collaboration was shown to have a moderating effect between the antecedents and the consequences (efficiency, effectiveness and profitability). Simatupang and Sridharan [14] highlighted that a firm that focuses on BPM practices should be able to support collaborative activities with its SC partners. There is a positive relationship between internal SCM resources and joint SCM resources, which in turn affect collaborative SCM processes and SCM execution [12] . However, the previous literature lacks empirical testing of the relationship between BPM and SCC, which are important for leveraged performance. The link between these two aspects needs to be identified to provide a better understanding of how intra-organisational development regarding BPM practice can help with collaborative activities and of the benefits that can, thereby, be achieved.. The early stage of our research empirically tested the interrelationships between BPM, SCC, collaborative advantage and organisational performance [15] . It provides empirical evidence that there is a positive relationship between the relationships under investigation. Hence, it only indicated the results in terms of the significance or non-significance of each hypothesis [15] . However, prior research still lacks insights into the actual practices of BPM and SCC, especially in the manufacturing sector in a developing economy. Based on this research gap, we argue that there is a need to capture instances of practitioners' views of the relationships between BPM, SCC, collaborative advantage and organisational performance, and to develop an understanding of the underlying factors guiding these interrelationships. Therefore, this research aims to provide a detailed understanding of the meanings, actions and opinions of real-world practitioners in their specific contextual situations and their experiences of the use of BPM practices, collaboration with SC partners and benefits achieved in terms of collaborative advantage and organisational performance. More specifically, this research focuses on the manufacturing sector in a developing economy, namely Thailand, an aspect which has mainly been neglected. The main research question that guided our research can be identified as: ''How do BPM and SCC interrelate to drive collaborative advantage and organisational performance?''. This can be broken down into three research sub-questions: (1) ''How does BPM help to improve organisational performance?''; (2) ''How does BPM help in collaborative activities?''; and (3) ''How do contextual factors impact on the link between BPM and SCC and the relationship benefits?''.. To answer these questions, a multi-case approach was adopted using four medium and large companies from the electronics and automotive industries in Thailand. Based on earlier research, BPM represents intra-organisational development, and we ascertained four elements of BPM, namely strategic alignment, information technology (IT), process orientation and improvement and people involvement [15] . We identified four elements of SCC, namely information sharing and communication, sharing common goals, joint activities and incentive alignment. These important elements of BPM and SCC were selected based on the most commonly used ones in previous research (based on the number of citations from Harzing's ''Publish or Perish'' (23 July 2014). The benefits were indicated in terms of collaborative advantage and organisational performance, and a framework was developed to explain these relationships. Next, a taxonomy was developed to identify different types of internal development (BPM) and external developments (SCC) and to illustrate how companies' performance can be improved. The taxonomy can help SC managers to enhance their understanding of intra-and inter-organisational development and shape the ways to manage and improve their SC to achieve higher SC performance.. To identify the role of BPM and SCC, and their benefits in terms of collaborative advantage and organisational performance, terms such as business process management (BPM), supply chain management, supply chain collaboration (SCC), collaborative advantage, organisational performance and intra-and inter-organisation were used to identify relevant keywords in research papers. The following section provides the relevant literature on BPM, SCC and benefits in terms of collaborative advantage and organisational performance. The research methodology is subsequently presented, followed by the case study analysis. Finally, the key research findings are summarised and discussed, and contributions and conclusions are highlighted.. 2 Literature review 2.1 Business process management BPM has been explained by various authors [16, 17] . According to Lindsay et al. [18] , BPM strives to better understand the key mechanisms of a business to improve and in some cases to radically change the business performance by identifying opportunities for new business, outsourcing, improving business efficiency and using technology within different areas of the business to support business processes. Van der Aalst et al. [17] suggested that BPM was a field of knowledge that covered the use of various methods, techniques and technologies to support business process changes, encouraging employees to become more involved. More recently, Chang [16] defined BPM as a process-oriented organisational approach used to design, analyse and improve business processes to effectively manage and improve organisational performance. In summary, BPM utilises both incremental and radical methodologies, focusing on processes, technology and the involvement of people to ensure that customer satisfaction is achieved in an effective way.. To capture the main elements of BPM, we define BPM by covering the four main elements most commonly highlighted by previous research [e.g. 16, 19] . The selection of these four elements was based on a number of citations from Harzing's (23 July 2014) ''Publish or Perish''. These four elements are strategic alignment, IT, process orientation and improvement and people involvement. Strategic alignment refers to long-term goals, the consideration of customer requirements and the internal characteristics of organisations and involves developing specific strategies and plans that can be implemented to maximise the value from process redesign and improvement [19] . Additionally, joint decision-making with SC partners is necessary for intra-organisational operations and the development of long-term plans. For instance, a firm and its SC partners could make joint decisions about demand forecasting and jointly establish and share common goals along a SC. IT is not developed to be used only within organisational boundaries but can also involve external IT interfaces and SC engagements. Process orientation is central to BPM and includes key elements such as process view/documentation, value stream mapping, process ownership and process measurement. BPM represents a convergence of previous process improvement approaches, as it provides information and a process management infrastructure for improvement [16, 19] . Both top management and employee empowerment need to be involved in BPM practices. Top management needs to be committed and to communicate effectively, setting organisational values and developing a suitable management style to improve organisational performance [20] . Additionally, empowering employees allows them to participate actively and creatively in their work.. Organisational performance is described as a multidimensional concept. It refers to how well an organisation fulfils both financial and market-oriented goals [21] . Financial goals are measured by figures such as sales growth, profit margin on sales and return on investment [5, 9] . Non-financial performance is measured, for example, by overall product quality, overall competitive position, overall customer service levels, core competences and capabilities [5, 9] . Non-financial performance measures can help shift attention away from short-term financial goals towards medium-and long-term goals [22] .. Several studies have revealed that BPM has a positive impact on organisational performance [23] [24] [25] [26] . However, there is limited research on the link between some attributes of BPM and organisational performance. A number of studies [19, 24] focused on the ''process'' concepts of BPM, its attributes and the links between attributes and benefits such as organisational performance and customer satisfaction. Smart et al. [19] empirically validated a BPM framework by considering the context of processes to characterise BPM. They identified five main dimensions of BPM, namely process strategy, process architecture, process measurement, process ownership and process improvement. Maddern et al. [24] examined the impact of BPM on service quality and customer satisfaction and highlighted that BPM is a critical factor in driving customer satisfaction. The relationship between process orientation and organisational performance was studied by Skirinjar et al. [26] . Their results showed that business process orientation leads to an improvement in both financial and non-financial performance. In summary, prior studies on BPM have mostly focused on some specific attributes of BPM. Hence, there is a lack of BPM research that includes all the main attributes covering the entire scope of BPM. Most studies of BPM have typically been narrowly defined and have focused on aspects within the organisational boundaries rather than investigating the link between BPM and the inter-organisational relationship. This study employed the case study approach as a followup to the large-scale survey [49, 50] to gain a deeper understanding of the empirical results. Regarding the case study selection, a multiple case design was adopted to further elaborate on the quantitative findings. This design is derived from diverse types of conditions and aims to have sub-groups of cases covering each type [49] . The case selection process was based on the criteria of size and industry: one medium-and one large-sized firm from the automotive and electronics industries. The size distinction was based on the official Thai definition: a medium-sized firm having 51-200 employees and a large-sized firm employing more than 200 people (The Ministry of Industry Thailand, 2013). This process allowed for some level of triangulation above the company level [49] . Overall, 15 firms meeting these criteria, which contributed to the first phase of the study, were selected and contacted via email and by phone. Finally, four cases were selected to participate in the interview process. The selected paradigmatic case studies allowed for a comparison of similarities and differences between firm size, industry type, relationship direction and relationship length. The identities of the companies have to remain anonymous because of confidentiality agreements, and they are referred to as follows (see also Fig. 3 ): ELC (a large electronics company), ALC (a large automotive company), EMC (a medium-sized electronics company) and AMC (a medium-sized automotive company). Appendix 1 provides the backgrounds of the participating companies.. An interview protocol was developed, based on the results of the large-scale survey, to ensure that all issues required were addressed. The interview questions were organised in a logical sequential order, with wording that was not too direct and too leading, resulting in clear and precise questions to ensure that the interview questions were effective [51] . Appendix 2 elaborates on the development of the interview questions. In relation to subquestion 1 (see Sect. 1), the interview questions asked participants to describe BPM and its practices, how BPM has helped to improve organisational performance, relationship difficulties and the solutions for dealing with challenges. In relation to our second research sub-question (see Sect. 1), the interview questions asked how BPM has helped collaborative activities, whether the firms had experienced relationship difficulties and what solutions have been implemented to address such challenges. In relation to our third research sub-question, the interview questions focused on relationship characteristics (i.e. the closeness of the relationship, the reasons for engaging the company in collaboration, relationship difficulties, solutions to the challenges and relationship length), as well as benefits that the company has achieved from working collaboratively with its SC partner, challenges to achieving collaborative advantage and solutions implemented to address such challenges. Additionally, questions covered how collaborative advantage has helped to improve organisational performance and what would happen if a company operated without a collaborative relationship.. After careful development, the interview protocol was translated into Thai. Then, the interview protocol was pilottested to assess whether it was workable and to identify any problems that might occur during the subsequent interview process.. Semi-structured interviews were employed between February and mid-March 2014. From each of the four companies, the member of personnel who had completed the large-scale survey was contacted. Interview questions were sent to the practitioners 3-5 days in advance to allow them time to prepare their answers to the interview questions. The average duration of each interview was one and a half hours. All interviews were digitally recorded, and field notes were also used to collect information during the interview. The voice recordings of the interviews were later transcribed into Thai and then translated into English. A case study database was developed and used for visualising the data and for developing tables and matrices containing various views used in the case study analysis.. The case study data analysis followed ''the data analysis spiral'' suggested by Creswell [52, p. 150 ]. The processes move along with the analytical circles in a nonlinear approach, touching on several facets of analysis and circling around and around [52] . The analysis procedures include: (1) data managing; (2) reading and memoing; (3) describing, classifying and interpreting; and (4) representing and visualising. The first task in the spiral begins with organising the data into an assessable format (''data managing'' procedure). Then, further notes were made to record the key ideas and concepts during the reading of the interview database (''reading and memoing'' procedure). After scanning through the database, ''conceptually clustered matrices'' were developed (''classification'' procedure). The development of conceptually clustered matrices is the most useful technique when: (1) a clear concept or theme has emerged from the initial analysis or (2) during early analysis, and after reading through the transcripts, the researcher finds that participants have given very similar or vastly different responses to questions and that unexpected variables, concepts, and themes have emerged [53] . In addition, rows and columns were created to bring research sub-topics, concepts and/or themes together, developing a summary documentation and analysis [53] . The conceptually clustered matrix ensures all the data fit into a reasonable format. It also presents a set of themes with information of each case, which lends itself to cross-case analysis for multiple case studies [53] . In this study, the main themes developed based on the research questions were: (1) the link between BPM and organisational performance; (2) the link between BPM and SCC; and (3) the contextual factors and benefits achieved from working collaboratively with SC partners. Additionally, some sub-themes (e.g. BPM regarding activities and solutions for short-term relationships) were identified at an early stage of the data analysis, as the participants provided similar explanations. The transcripts from the interviews were entered into the matrix based on specific themes and sub-themes that had been identified. The case study database is developed and an information summary of each case is shown in a

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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 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 B I O O O O O O B I I O O O O B I 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 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 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 O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 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O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 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 O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 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Clustering Music Recordings Based on Genres Abstract-Existing systems for automatic genre classification follows a supervised framework that extracts genre-specific information from manually-labeled music data and then identifies unknown music data. However, such systems may not be suitable for personal music management, because manually labeling music based on individually-defined genres can be labor intensive and subject to inconsistence from time to time. This work studies an unsupervised paradigm for music genre classification. It is aimed to partition a collection of unknown music recordings into several clusters such that each cluster contains recordings in only one genre, and different clusters represent different genres. This enables users to organize their personal music database without needing specific knowledge about genre. We investigate how to measure the genre similarities between music recordings and estimate the genre population size of a music collection. Our experiment results show the feasibility of clustering music recordings by genre. A music genre represents a type of music that has the common characteristics shared by its members and can be distinguished from other types of music. Automatic classification of music genres [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] serves as an effective way to structure and organize vast numbers of music files nowadays. So far, most genre classification systems [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] follow a supervised framework that extracts genre-specific information from manually-labeled music data and then identifies unknown music data. However, such systems may not be suitable for personal music management, because manually labeling music based on individually-defined genres can be labor intensive and subject to inconsistence from time to time. Unlike the supervised genre classification, this work studies an unsupervised paradigm for music genre classification. It is aimed to partition a collection of unknown music recordings into several clusters such that each cluster contains recordings in only one genre, and different clusters represent different genres. This enables users to organize their personal music database without needing specific knowledge about genre.. As a closest related work to this study, [12] proposed an unsupervised classification framework to identify the genres of music clips. They used hidden Markov modeling to characterize the genre information of each music clip, thereby measuring the similarities between clips. Although music clips can then be grouped into clusters after knowing which clips are similar or dissimilar to each other, [12] did not study the issue as to how many clusters should be generated. In general, the greater the number of clusters generated, the higher the chance that within-cluster music clips belong to the same genre. However, if too many clusters are generated, music clips in the same genre would be split across multiple clusters, and hence the clustering will not be completed. Clearly, the optimal number of clusters equals the number of genres, which is unknown and needs to be estimated. Our major efforts in this study are thus put on investigating how to measure the genre similarities between music recordings and estimate the genre population size of a music collection.. The remainder of this paper is organized as follows. In Section II, we formulate the problem of genre-based clustering of music data and describe the performance assessment method used in this study. Section III introduces the major components of the proposed system, namely, inter-recording similarity computation, cluster generation, and the estimation of the optimal number of clusters. Section IV discusses our experiment results. Then, in Section V, we present our conclusions and indicate the direction of our future work. We have studied an unsupervised clustering paradigm for identifying music recordings in the same genre. This is done by measuring the similarities between music recordings and using the hierarchical agglomerative clustering to group together the recordings deemed similar to one another. We have also proposed a method based on the Rand index to determine the optimal number of clusters automatically, corresponding to the genre population size. Experiments show the feasibility of using unsupervised clustering to index music data. Despite the viability, the methods proposed in this study can only be regarded as a preliminary investigation in realistic music data indexing applications. To be of more practical use, more work is needed to study the effectiveness and efficiency of clustering a large scale of music collection. The fundamental problem would be how to characterize music data as audio features more closely related to music genre.

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 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 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 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 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 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


Branched polymers and hyperplane arrangements Abstract. We generalize the construction of connected branched polymers and the notion of the volume of the space of connected branched polymers studied by Brydges and Imbrie [BI], and Kenyon and Winkler [KW] to any hyperplane arrangement A. The volume of the resulting configuration space of connected branched polymers associated to the hyperplane arrangement A is expressed through the value of the characteristic polynomial of A at 0. We give a more general definition of the space of branched polymers, where we do not require connectivity, and introduce the notion of q-volume for it, which is expressed through the value of the characteristic polynomial of A at −q. Finally, we relate the volume of the space of branched polymers to broken circuits and show that the cohomology ring of the space of branched polymers is isomorphic to the Orlik-Solomon algebra. Brydges and Imbrie [BI] , and Kenyon and Winkler [KW] study the space of branched polymers of order n in R 2 and R 3 . In their definition, a branched polymer of order n in R D is a connected set of n labeled unit spheres in R D with nonoverlapping interiors. To each polymer P corresponds a graph G P on the vertex set [n] where (i, j) ∈ E(G P ) if and only if spheres i and j touch in the polymer. The space of branched polymers of order n in R D can be parametrized by the D-dimensional angles at which the spheres are attached to each other. If G P has a cycle, this parametrization becomes ambiguous. However, since polymers containing a cycle of touching spheres have probability zero, this ambiguity is not of concern. Brydges and Imbrie [BI] , and Kenyon and Winkler [KW] compute the volume of the space of branched polymers in R 2 and R 3 , which are (n − 1)!(2π) n−1 and n n−1 (2π) n−1 , respectively. They show that if we relax the requirement that the spheres in the polymer have radii 1, the volume of the space of branched polymers in R 2 remains the same, while the volume of the space of branched polymers in R 3 changes.. Intrigued by the robustness of the space of branched polymers in R 2 under the change of radii, we generalize this notion differently from how it is done in [BI, KW] . Under our notion of polymers, the volume of the space of polymers is independent of the radii in all cases.. We associate the space of branched polymers to any hyperplane arrangement A. The polymers corresponding to the braid arrangement B n coincides with the definition of branched polymers in R 2 given above. We also broaden the notions of branched polymers, by not requiring polymers to be connected. We define the volume of the space of such polymers and show that it is invariant under the change of radii. In the case of the braid arrangement, the volume of the space of connected branched polymers associated to B n is (n − 1)!(2π) n−1 = (−2π) r(Bn) χ Bn (0), where r (B n ) is the rank of B n and χ Bn (t) is the characteristic polynomial of B n . In our generalized notion of volume, weighted with q, the volume of the space of branched polymers associated to B n is (−2π) r(Bn) χ Bn (−q). The volume of the space of connected branched polymers associated to B n is a specialization of this q-volume at q = 0.. A theorem of the same flavor holds for any of our polymers.. Theorem. The q-volume of the space of branched polymers associated to a central hyperplane arrangement A is (−2π) r(A) χ A (−q). Furthermore, the volume of the space of connected branched polymers associated to A is a specialization of its q-volume at q = 0.. In the case that A is a graphical arrangement, we recover the G-polymers of [KW] , and the Theorem can be rephrased in terms of the chromatic polynomial of the graph G. We also relate the volume of the space of branched polymers to broken circuits and the Orlik-Solomon algebra. Finally, we prove that the cohomology ring of the space of branched polymers is isomorphic to the Orlik-Solomon algebra, and conjecture the same for for the space of connected branched polymers.. The outline of the paper is as follows. In Section 2 we explain how the notion of branched polymers in R 2 from [BI, KW] translates to polymers associated to the braid arrangement B n . In Section 3 we give a general definition of connected branched polymers, as well as branched polymers (where we do not require connectivity) associated to any arrangement A. We define the notion of q-volume of the space of branched polymers and restate the Theorem about the value of the q-volume of the space of branched polymers. In Section 4 we prove the Theorem. In Section 5 we recover the G-polymers of [KW] from the graphical arrangement A G . We relate the volumes of branched polymers to broken circuits in Section 7. We conclude in Section 8 by proving that the cohomology ring of the space of branched polymers is the Orlik-Solomon algebra, and we conjecture that the cohomology ring of the space of connected branched polymers is the same.

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