Design is a complex activity that can be analysed from a wide variety of perspectives. This paper attempts to look at the individual problem solving process, taking into account psychological arguments. We characteris...
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ISBN:
(纸本)9781581134452
Design is a complex activity that can be analysed from a wide variety of perspectives. This paper attempts to look at the individual problem solving process, taking into account psychological arguments. We characterise some of the phases involved in the design process, namely the constraints identification, the optimisation of solution space and the reuse process. We highlight a three-dimensional framework of how the constraints identification impacts on the solution space which, in turn, determines the range of the components that will be eligible for reuse. We discuss this argument through examples from both inside and outside the software engineering field.
This paper describes a new fault-tolerant routing algorithm for the k-ary n-cube using the concept of "probability vectors". To compute these vectors, a node determines first its faulty set, which contains a...
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ISBN:
(纸本)9781581134452
This paper describes a new fault-tolerant routing algorithm for the k-ary n-cube using the concept of "probability vectors". To compute these vectors, a node determines first its faulty set, which contains all its neighbouring nodes that are faulty or unreachable due to faulty nodes or links. Each node then calculates a probability vector, where the i-th element represents the probability that a destination node at distance i cannot be reached using a minimal path due to a faulty node or link. The probability vectors are used by all the nodes to achieve an efficient fault-tolerant routing in the network. Results from a performance analysis presented below show that the new algorithm exhibits good fault-tolerance properties in terms of the achieved percentage of reachability and routing distances.
We demonstrate a computational process by which transcription factor binding sites can be elucidated using genome-wide expression and binding profiles. The profiles direct us to the intergenic locations likely to cont...
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We demonstrate a computational process by which transcription factor binding sites can be elucidated using genome-wide expression and binding profiles. The profiles direct us to the intergenic locations likely to contain the promoter regions for a given factor. These sequences are multiply and locally aligned to give an anchor motif from which further characterization can take place. We present bases for and assumptions about the variability within these motifs which give rise to potentially more accurate motifs, capture complex binding sites built upon the basis motif, and eliminate the constraints of the currently employed promoter searching protocols. We also present a measure of motif quality based on the occurrence of the putative motifs in regions observed to contain the binding sites. The assumptions, motif generation, quality assessment and comparison allow the user as much control as their a priori knowledge allows.
Broadcast algorithms for wormhole-switched meshes have been widely reported in the literature. However, most of these algorithms handle broadcast in a sequential manner and do not scale well with the network size. As ...
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ISBN:
(纸本)9781581134452
Broadcast algorithms for wormhole-switched meshes have been widely reported in the literature. However, most of these algorithms handle broadcast in a sequential manner and do not scale well with the network size. As a consequence, many parallel applications cannot be efficiently supported using existing algorithms. Motivated by these observations, this paper presents a new broadcast algorithm based on our previously proposed Coded Path Routing (or CPR for short) [1]. The main feature of the proposed algorithm lies in its ability to perform broadcast operations with a high degree of parallelism. Furthermore, its performance is insensitive to the network size, i.e., only two message-passing steps are required to implement a broadcast operation irrespective of the network size. Results from a comparative analysis reveal that the new algorithm exhibits superior performance characteristics over those of the well-known Recursive Doubling, Extending Dominating Node and Network Partitioning algorithms.
This paper presents a novel approach for the problem of generating tiled code for nested for-loops using a tiling transformation. Tiling or supernode transformation has been widely used to improve locality in multi-le...
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ISBN:
(纸本)9781581134452
This paper presents a novel approach for the problem of generating tiled code for nested for-loops using a tiling transformation. Tiling or supernode transformation has been widely used to improve locality in multi-level memory hierarchies as well as to efficiently execute loops onto non-uniform memory access architectures. However, automatic code generation for tiled loops can be a very complex compiler work due to non-rectangular tile shapes and iteration space bounds. Our method considerably enhances previous work on rewriting tiled loops by considering parallelepiped tiles and arbitrary iteration space shapes. The complexity of code generation for tiling transformation is now reduced to the complexity of code generation for any linear transformation. Experimental results which compare all so far presented approaches, show that the proposed approach for generating tiled code is significantly accelerated.
For the solution of a minimization problem, a neutron scattering simulation needs accurate and efficient derivatives of an objective function in the form of a Fortran 77 program with about 3,500 lines of code. We use ...
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For the solution of a minimization problem, a neutron scattering simulation needs accurate and efficient derivatives of an objective function in the form of a Fortran 77 program with about 3,500 lines of code. We use the Adifor system implementing the technology of automatic differentiation to transform the given computer code into another program capable of evaluating the objective function and its derivatives. Compared to numerical differentiation, the derivatives obtained from applying automatic differentiation in this black-box fashion are free from truncation error and, in this application, their computation requires less time. To increase the efficiency of automatic differentiation further, a technique called interface contraction is used. The idea of interface contraction is to exploit the local structure of a given code by temporarily reducing the number of derivatives propagated through the code. By reporting performance results, we show the significance of interface contraction in the neutron scattering application. We also demonstrate the simplicity of the approach and argue that interface contraction should be incorporated into future automatic differentiation tools.
Although smart cards are becoming used in an increasing number of applications, there is small literature of the implementation issues for smart cards. This paper describes the issues and considerations that need to b...
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Although smart cards are becoming used in an increasing number of applications, there is small literature of the implementation issues for smart cards. This paper describes the issues and considerations that need to be taken into account when implementing the key generation step of a cryptographic algorithm widely used nowadays, RSA. Smart cards are used in many applications that require a tamper resistant area. Therefore, smart cards that use cryptography have to provide encryption, decryption, as well as key generation inside its security perimeter. RSA key generation is a concern for on-card implementation of RSA cryptosystem, as it usually takes a long time. In this paper, two simple but efficient key generation algorithms are evaluated, in addition to a simple but not very efficient algorithm. The paper discusses in detail how to build fast implementations for the three algorithms presented, using smart cards with cryptocoprocessor.
Mobile clients have limited display and navigation capabilities. To browse a set of documents, an intuitive method is to navigate through concept hierarchies. To reduce semantic loading for each term that represents t...
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ISBN:
(纸本)9781581134452
Mobile clients have limited display and navigation capabilities. To browse a set of documents, an intuitive method is to navigate through concept hierarchies. To reduce semantic loading for each term that represents the concepts and the cognitive loading of users due to the limited display, similar documents are grouped together before concept hierarchies are constructed for each document group. Since the concept hierarchies only represent the salient concepts in the documents, term extraction is necessary. Our pilot experiments showed that an unconventional combination of term frequency and inverse document frequency yielded similar performance (i.e. 71%) to previous work and the use of terms in titles achieved better performance than previous work (i.e. 82%). Our preliminary results of building concept hierarchies after clustering compared to that without is encouraging (c.f. 82% and 67%). We believe that further research can enhance the performance of concept hierarchies to a level for commercial deployment for mobile clients.
The Internet has led to the formation of a global information infrastructure. To explore a web site, a site map would be useful as a short cut for a user to locate for the target information in a structured and effici...
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The Internet has led to the formation of a global information infrastructure. To explore a web site, a site map would be useful as a short cut for a user to locate for the target information in a structured and efficient manner, rather than drilling into the web site following hyperlinks, reading possibly irrelevant information. Useless information impacts a mobile web environment, where mobile clients are only connected with unreliable wireless channels of limited bandwidth. Structured web page organization at the web server proxy is an important issue to resolve to provide efficient browsing experience for web clients, while minimizing the browsing of unrelated pages or sites. In this paper, we adopt the Document Information Extraction mechanism to construct a document cluster dynamically and intelligently with respect to a requested root web page. The document cluster works like a dynamic site map, spanning across several web sites. The clusters are generated and stored in XML format at proxy server so that it can potentially benefit a large number of mobile clients. Clients process the XML clusters and transform them to be visualized through VRML or DOM. For VRML, a transformer is built at the client-side to support a three-dimensional modeling view. For DOM, JavaScript is used for accessing the parsed XML data to produce a two-dimensional tree output.
It is envisaged that the grid infrastructure will be a large-scale distributed software system that will provide high-end computational and storage capabilities to differentiated users. A number of distributed computi...
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