Fast and accurate fault detection is becoming an essential component of management software for mission critical systems. A good fault detector makes possible to initiate repair actions quickly, increasing the availab...
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ISBN:
(纸本)1595931082
Fast and accurate fault detection is becoming an essential component of management software for mission critical systems. A good fault detector makes possible to initiate repair actions quickly, increasing the availability of the system. The contribution of this paper is twofold. First a new concept of supervised and unsupervised monitoring is proposed for system fault detection. We use a statistical method, canonical correlation analysis (CCA), to model the contextual dependencies between system inputs u and internal behavior x. By means of CCA, the space x is transformed into two subsets of variables, which are monitored in a supervised and unsupervised manner respectively. By doing so, our approach can reduce the false alarms resulting from unusual workload changes, and hence achieve high fault detection rate. Second, in order to test the performance of our approach, we simulate a variety of system faults in a real e-commerce application based on the multi-tiered J2EE architecture. Experimental results demonstrate that the CCA based approach can detect injected failures at their early stages when unusual phenomenon is very weak, and hence contribute to enormous time and cost savings in managing large scale distributed systems. Copyright 2006 acm.
Refactoring, as a software engineering discipline has emerged over recent years to become an important aspect of maintaining software. Refactoring refers to the restructuring of software according to specific mechanic...
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ISBN:
(纸本)1595931082
Refactoring, as a software engineering discipline has emerged over recent years to become an important aspect of maintaining software. Refactoring refers to the restructuring of software according to specific mechanics and principles. In this paper, we describe a tool that allows refactoring data across multiple versions of seven open-source software systems to be collected. The tool automates the identification of refactorings as program transformations between consecutive software releases. The same tool thus allowed an empirical analysis of software development across versions from the perspective of those transformations. We describe results for the systems analysed and point to key conclusions from our analysis. In particular, we investigate a problematic empirical question as to whether certain refactorings are related, i.e., they cannot be undertaken in isolation without other refactorings being undertaken in parallel. In this context, we focus specifically on the four most common refactorings identified by the tool from three of the open-source systems and use a dependency graph to inform conclusions about the empirical data extracted by the tool. An interesting result relating to some common refactorings is described. Copyright 2006 acm.
The Trusted computing Group (TCG) is an industry consortium which has invested in the design of a small piece of hardware (roughly a smartcard), called a Trusted Platform Module (TPM), and associated APIs and protocol...
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ISBN:
(纸本)1595931082
The Trusted computing Group (TCG) is an industry consortium which has invested in the design of a small piece of hardware (roughly a smartcard), called a Trusted Platform Module (TPM), and associated APIs and protocols which are supposed to help increase the reliability of TPM-endowed computing platforms (trusted platforms). The TCG envisions that boot loaders, OSes and applications programs on trusted platforms will all collaborate in building a cryptographic hash chain which represents the current execution state of the platform, and which resides on the TPM. Remote sites can then verify that the platform in question is "in a trusted state" by requesting the TPM to produce a signed data blob containing the value of this hash chain, which can then be compared against a library of recognized ("trusted") values;this process is called remote attestation, and the whole picture is sometimes referred to as integrity-based computing (IBC). We argue that there is a fundamental gap between the stated goals of the TCG's IBC and the central technology that is intended to achieve these goals, which gap is simply that remote attestation asks the attesting platform to answer the wrong question - the platform is not attesting to its security state, but rather to its execution state, and this underlies all of the troublesome use cases, as well as a number of the practical difficulties, of the TCG world-view. One response to this is to replace standard TCG attestation with property-based attestation (PBA), which places the emphasis on deriving security properties from (potentially) elaborate trust models and conditional statements of security property dependencies. Herein the central rôle for IBC of trust and deriving consequences from precise trust models becomes clear. Finally, we claim that the TCG's own remote attestation is most properly viewed in fact as a form of PBA, with a certain simple trust model and database of security properties. From this point of view, it becomes c
Wearable computers aim to support and improve KM abilities for the worker and the organization. However it is also expected that the wearable computers will present them with many challenges along the way. The followi...
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In this paper, we examine the problem of computing the greatest commondivisor (GCD) of univariate polynomials represented in different bases. When the polynomials are represented in Newton basis or a basis of orthogon...
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ISBN:
(纸本)1595932763
In this paper, we examine the problem of computing the greatest commondivisor (GCD) of univariate polynomials represented in different bases. When the polynomials are represented in Newton basis or a basis of orthogonal polynomials, we show that the well-known Sylvester matrix can be *** give fraction-free and modular algorithms to directly compute the GCD in the alternate *** algorithms are suitable for computation in domains where growth of coefficients inintermediate computations area central *** the cases of Newton basis and bases using certain orthogonal polynomials, we also show that the standard sub resultant algorithm can be applied easily. If the degrees of the input polynomials is at most n and the degree of the GCD is at least n/2, our algorithms out perform the corresponding algorithms using the standard power basis. Copyright 2006 acm.
A Living Lab refers to a setting created with specific targets and a clear structure, but in the same time dealing with the uncontrollable dynamics of daily life. Wearable computing means a paradigm shift: instead of ...
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Particle-based simulation methods are used to model a wide range of complex phenomena and to solve time-dependent problems of various scales. Effective visualization of the resulting state should communicate subtle ch...
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Refactoring, as a software engineering discipline has emerged over recent years to become an important aspect of maintaining software. Refactoring refers to the restructuring of software according to specific mechanic...
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ISBN:
(纸本)1595932186
Refactoring, as a software engineering discipline has emerged over recent years to become an important aspect of maintaining software. Refactoring refers to the restructuring of software according to specific mechanics and principles. In this paper, we describe an analysis of the results from a tool whose purpose was to identify and extract refactorings from seven open-source Java systems. In particular, we analyzed the mechanics of the most commonly and least commonly applied refactorings to try and account for their frequency. Results showed the most common refactorings of the fifteen coined a 'Gang of Six', to be generally those with a high in-degree and low out-degree when mapped on a dependency graph;the same refactorings also featured strongly in the remedying of bad code smells. Remarkably and surprisingly, inheritance and encapsulation-based refactorings were found to have been applied relatively infrequently - we offer explanations for why this may be the case. The paper thus identifies 'core' refactorings central to many of the changes made by developers on open-source systems. While we can not guarantee that developers consciously undertake refactoring in any sense, the empirical results demonstrate that simple renaming and moving fields/methods between classes are common components of open-source system re-engineering. From a wider software engineering perspective, knowledge of what a modification will incur in likely sub-tasks is of value to developers whether working on open-source or other forms of software. Copyright 2006 acm.
The proceedings contain 128 papers. The topics discussed include: fast and reliable random number generators for scientific computing;large-scale computations with the unified Danish Eulerian model;a chemical engineer...
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ISBN:
(纸本)3540290672
The proceedings contain 128 papers. The topics discussed include: fast and reliable random number generators for scientific computing;large-scale computations with the unified Danish Eulerian model;a chemical engineering challenge problem that can benefit from interval methods;interval based Markov Decision processes;a verification method for solutions of linear programming problems;on the approximation of interval functions;the distributed interval geometric machine model;new algorithms for statistical analysis of interval data;on efficiency of tightening bonds in interval global optimization;applying software testing matrices to lapack;parallel algorithms for balanced truncation model reduction of sparse systems;and applying high performance computing techniques in astrophysics.
In this paper, we propose a practical and systematical solution to the mapping problem that is from 3D marker position data recorded by optical motion capture systems to joint trajectories together with a matching ske...
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ISBN:
(纸本)1595933212
In this paper, we propose a practical and systematical solution to the mapping problem that is from 3D marker position data recorded by optical motion capture systems to joint trajectories together with a matching skeleton based on least-squares fitting techniques. First, we preprocess the raw data and estimate the joint centers based on related efficient techniques. Second, a skeleton of fixed length which precisely matching the joint centers are generated by an articulated skeleton fitting method. Finally, we calculate and rectify joint angles with a minimum angle modification technique. We present the results for our approach as applied to several motion-capture behaviors, which demonstrates the positional accuracy and usefulness of our method. Copyright 2006 acm.
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