Pilot implementations of reliable systems

This paper describes the pilot implementation of a modifiable reliable system. On the basis of this work, we have been led to conclusions on necessary hardware and software features for supporting a reliable system, techniques for building such systems, and the scope of the results to be expected from a pilot implementation.     

Linear-time border-tracing algorithms for quadtrees

In applications where the quadtree is used as an underlying object representation, a number of basic operations are implemented as a trace along the border of the object's region. A technique is presented that determines a way to shift any given scene (as well as its quadtree), so that the border of all the objects in the scene can be traversed in time proportional to the length of all the borders in the scene (or the number of blocks when the scene is represented as a quadtree). This determination is shown to be performed in time proportional to the length of all the borders in the scene. This allows the direct translation of a number of chain-code algorithms into quadtree algorithms without loss of asymptotic worst-case efficiency. This results in improved worst-case analyses of algorithms that convert chain codes into quadtrees and that perform connected component labeling of images represented as quadtrees.     

Analyzing scalability of parallel systems with unbalanced workload

This paper presents a new formulation of the isoefficiency function which can be applied to parallel systems executing balanced or unbalanced workloads. This new formulation allows analyzing the scalability of parallel systems under either balanced or unbalanced workloads. Finally, the validity of this new metric is evaluated using some synthetic benchmarks. The experimental results allow assessing the importance of considering the unbalanced workloads while analyzing the scalability of parallel systems.     

Secure one snapshot protocol for concurrency control in real-time stock trading systems

To prevent any data from being accessed by unauthorized users, it is necessary for stock trading systems (STS) to use multilevel secure database management systems in controlling concurrent executions among multiple transactions. In STS, analytical transactions as well as mission critical transactions are executed concurrently, which makes it difficult to use traditional secure real-time transaction management schemes for STS environment. In this paper, we propose the read-down relationship-based secure one snapshot protocol (SOS) that is devised for the secure real-time transaction management in STS. By maintaining an additional one snapshot as well as working database, SOS blocks covert-channels without causing the priority inversion phenomenon. We introduce the process of SOS protocol with some examples, present the proofs of devised protocol, and then evaluate the performance gains by means of simulation method.     

Linear-time algorithm for the matched-domination problem in cographs

Let G=(V, E) be a graph without isolated vertices. A matching in G is a set of independent edges in G. A perfect matching M in G is a matching such that every vertex of G is incident to an edge of M. A set S? V is a paired-dominating set of G if every vertex not in S is adjacent to a vertex in S and if the subgraph induced by S contains a perfect matching. The paired-domination problem is to find a paired-dominating set of G with minimum cardinality. This paper introduces a generalization of the paired-domination problem, namely, the matched-domination problem, in which some constrained vertices are in paired-dominating sets as far as they can. Further, possible applications are also presented. We then present a linear-time constructive algorithm to solve the matched-domination problem in cographs.? ^?A preliminary version of this paper has appeared in: Proceedings of the 4th IASTED International Conference on Computational Intelligence (CI’2009), Honolulu, Hawaii, USA, 2009, pp. 120–126.      

Linear-time simulation of multihead turing machines

The main result of this paper is that, given a Turing machine M with k-heads on a d-dimensional tape, one can effectively construct a Turing machine M′ with k d-dimensional tapes but only one head per tape and one additional linear single-head tape which simulates M in linear-time.     

Linear-time border-tracing algorithms for quadtrees

In applications where the quadtree is used as an underlying object representation, a number of basic operations are implemented as a trace along the border of the object's region. A technique is presented that determines a way to shift any given scene (as well as its quadtree), so that the border of all the objects in the scene can be traversed in time proportional to the length of all the borders in the scene (or the number of blocks when the scene is represented as a quadtree). This determination is shown to be performed in time proportional to the length of all the borders in the scene. This allows the direct translation of a number of chain-code algorithms into quadtree algorithms without loss of asymptotic worst-case efficiency. This results in improved worst-case analyses of algorithms that convert chain codes into quadtrees and that perform connected component labeling of images represented as quadtrees.The support of the National Science Foundation under Grant IRI-88-02457 is gratefully acknowledged.     

用于依赖快照的高效写算法HPSW

使用快照技术可以生成存储系统在某时间点完全可用的数据副本,从而可使用该副本对存储系统实现备份、测试、在线分析和数据挖掘等操作。对快照的各种实现技术进行了分类与比较,详细说明了依赖快照的实现原理及优点,并针对在写依赖快照时可能造成的数据不一致的问题提出了一种高效的写算法HPSW;实验表明该算法具有良好的性能,克服了依赖快照的缺点,具有很好的实际应用价值。     

GMRES implementations and residual smoothing techniques for solving ill-posed linear systems

There are verities of useful Krylov subspace methods to solve nonsymmetric linear system of equations. GMRES is one of the best Krylov solvers with several different variants to solve large sparse linear systems. Any GMRES implementation has some advantages. As the solution of ill-posed problems are important. In this paper, some GMRES variants are discussed and applied to solve these kinds of problems. Residual smoothing techniques are efficient ways to accelerate the convergence speed of some iterative methods like CG variants. At the end of this paper, some residual smoothing techniques are applied for different GMRES methods to test the influence of these techniques on GMRES implementations.     

Determining the number of Kanbans for unbalanced serial production systems

This paper deals with the problem to determine the number of Kanbans for unbalanced serial production systems under the stochastic conditions. The simulation experiments for the constructed model of Kanban system derive the fundamental information about the problem, and an algorithm to determine the optimal number of Kanbans is proposed.     

Linear-time LUP decomposition of forest-like matrices

A square matrix M has an LUP decomposition if it can be written as LUP, where L is a unit lower-triangular matrix, U is an upper-triangular matrix, and P is a permutation matrix. We present a linear-time algorithm for finding an LUP decomposition for a nonsingular neighborhood matrix of a tree. We also identify a more general class of matrices we call forest-like for which the algorithm can be modified.     

OSI implementations in Korea

Research and development on OSI became a key issue in many Korean R&D projects related to computer, telecommunications and services. The Korean computer and communications industry also finds their possible area of expansion through OSI-compatible products. But claiming OSI as the future direction in Korea at the national/government level is not near. This short paper presents various present and future R&D projects on OSI in Korea. These include ISDN, LAN, Videotex, Teletex, protocol testing, mixed mode terminal, network architecture etc.     

Metrics for assessment of designs and implementations during reengineering of computer-based systems

Modern computer-based systems have many required characteristics, including performance, concurrency, timeliness, availability, dependability, safety and security. Aging computer-based systems are being reengineered to exploit distributed and highly parallel hardware platforms, in order to accommodate increased functional requirements and to achieve dependability. Simultaneously, reengineering is introducing modern software engineering principles such as component layering, encapsulation and information hiding, in order to reduce maintenance burdens and to simplify future enhancement. This paper summarizes a process for reengineering of computer-based systems to achieve these goals. The process incorporates experience gained through the reengineering of the Weapons Selection module and the Surface Operations module of the AEGIS Weapon System. A key component of the reengineering process is themission critical software architecture (MCSA), a hierarchical view of systems that includes the abstraction levels of programs, tasks, packages, procedures, and statements. To guide the reengineering processes of software transformation, concurrency metrics are defined at the procedure, package and task levels of the MCSA. The paper defines the intermediate representation (IR) needed to compute the metrics, and shows how to use the IR to compute several metrics: the percentage of concurrency within procedures and packages, and the amount of potential concurrency among tasks. The metrics are important in any reengineering approach that iteratively transforms design and code, or that deals with system configuration (the integration of software, hardware and humanware).This work is supported in part by the US NSWC (N00178-95-R-2007, N60921-94-M-6096, N60921-94-M-1960, N60921-94-M-2555, N60921-95-M-0311), by the State of New Jersey (SBR-421290), and by the US ONR(N00014-92-J-1367).     

Evaluating the performance of FFT library implementations on modern hybrid computing systems

The Journal of Supercomputing - Fast Fourier transform is widely used to solve numerous scientific and engineering problems. In particular, this transform is behind the software dealing with speech...     

Towards an interpretative integrative framework to conceptualise social processes in large information systems implementations

This paper develops a new interpretative framework to study large information systems implementations. This framework is used to make explicit the various links between the implementation process, the wider organisation and external context. This framework is applied to a substantive case to integrate relevant organisational levels and distinct activity domains, as well as the interconnections between those levels and domains through time. More specifically, the paper extends a previous substantive case analysis with an interpretivist conceptualisation and theory triangulation in order to uncover the deeper structure and meanings embedded in a major information systems (IS) implementation process. The research scope of the IS implementation ranged from initial project formulation, to system development and management training, managing support from key stakeholders, and marginal system use. The substantive case, which has been published elsewhere [33], is based on a national information systems initiative to support the decentralisation and modernisation of management functions in health districts of the Ministry of Public Health in Ecuador. A key objective of this paper is to build a process theory of IS implementation, situated within the context of the substantive case study.     

Neural network applications in fault diagnosis and detection: an overview of implementations in engineering-related systems

The use of artificial neural networks (ANN) in fault detection analysis is widespread. This paper aims to provide an overview on its application in the field of fault identification and diagnosis (FID), as well as the guiding elements behind their successful implementations in engineering-related applications. In most of the reviewed studies, the ANN architecture of choice for FID problem-solving is the multilayer perceptron (MLP). This is likely due to its simplicity, flexibility, and established usage. Its use managed to find footing in a variety of fields in engineering very early on, even before the technology was as polished as it is today. Recurrent neural networks, while having overall stronger potential for solving dynamic problems, are only suggested for use after a simpler implementation in MLP was attempted. Across various ANN applications in FID, it is observed that preprocessing of the inputs is extremely important in obtaining the proper features for use in training the network, particularly when signal analysis is involved. Normalization is practically a standard for ANN use, and likely many other decision-based learning methods due to its ease of use and high impact on speed of convergence. A simple demonstration of ANN’s ease of use in solving a unique FID problem was also shown.

     

Iterative method for the computation of unbalanced fault in m-phase power systems

The symmetrical components transformation used in 3-phase systems is extended to the use in m-phase systems. It has been shown that to be decoupled by the transformation, an impedance or admittance matrix must possess a group property put forth in this paper. This property is also proved to be sufficient. An iterative method that determined fault currents in a general type of unbalanced fault is presented. The method that requires replacements of matrix elements, is particularly suitable for programming via the digital computer.     

Linear-time robot localization and pose tracking using matching signatures

A feature-based method for global localization of mobile robot using a concept of matching signatures is presented. A group of geometric features, their geometric constraints invariant to frame transform, and location dependent constraints, together are utilized in defining signature of a feature. Plausible global poses are found out by matching signatures of observed features with signatures of global map features. The concept of matching signatures is so developed that the proposed method provides a very efficient solution for global localization. Worst-case complexity of the method for estimating and verifying global poses is linear with the size of global reference map. It will also be shown that with the approach of random sampling the proposed algorithm becomes linear with both the size of global map and number of observed features. In order to avoid pose ambiguity, simultaneous tracking of multiple pose hypotheses staying within the same framework of the proposed method is also addressed. Results obtained from simulation as well as from real world experiment demonstrate the performance and effectiveness of the method.     

实时CORBA线程研究与实现

近年来实时CORBA的在金融、电信、保险、医疗、制造业等行业发挥着越来越重要的作用,开发基于实时CORBA的应用程序,提高系统端对端的预测能力,使系统具有可靠健壮的性能.首先论述了实时CORBA体系结构与线程控制机制,对实时CORBA的ORB、POA与线程控制机制关系、实时CORBA线程的实现方式、线程的管理策略作了分析讨论,在这基础上讨论了建立实时系统的应用实例,将CORBA优先映射为本地优先,提供了灵活的线程管理机制,有效防止了线程的优先级翻转.