Defects in multistage manufacturing processes (MMPs) decrease profitability and product quality. Therefore, MMP parameter optimization within a range is essential to prevent defects, achieve dynamic accuracy, and accommodate manufacturing tolerances. However, existing studies only focused on optimization in a single manufacturing stage of MMP, such as the weaving stage in fabric manufacturing. Furthermore, existing methods optimize for a single value rather than a range. Thus, we propose a novel approach called multistage parameter optimization for rule generation (MPORG) to prevent the occurrence of defects in MMPs. In the proposed approach, key parameters are identified and optimized to a range for each defect type. Subsequently, the optimized parameters for each defect type are merged. Our approach is novel because it optimizes parameters to a range rather than a single value, allowing engineers to select a value in this range according to their experience. It also provides results that are specific to a product type. Our approach outperformed the classification and regression tree (CART) algorithm and multiresponse CART method in experiments on an empirical fabric manufacturing dataset that we gathered. The experimental results demonstrated that the MPORG approach can prevent the occurrence of single-type or multiple-type defects by approximately 89%.

In batch production systems, detecting low-yield machines is essential for minimizing the production of defective pieces, which is a complex problem that currently requires multiple experts, considerable capital, or a combination of both to overcome. To solve this problem, we proposed a cost-efficient and straightforward method that involves using maximum likelihood estimation and bootstrap confidence intervals to estimate per-machine yield; this method enables identification of low-yield machines and generation of a list of these machines. Manufacturing engineers can use the list to perform necessary verification and maintenance processes. Before implementing this method, a manufacturer with 50–500 machines should build a dataset containing approximately 6–20 times as many batches as there are production machines. When this condition is met, the proposed method can be used effectively to detect up to five low-yield machines.

Efficient online liveness fault detection is crucial to cloud systems. Most current online liveness fault detection techniques, such as system layer heartbeating, use a single unreliable detector to detect cloud system liveness. A single unreliable detector requires a certain amount of time to detect faults to avoid misjudgment, regardless of the type of fault detected. However, many faults can be detected by other detectors more quickly. Therefore, this article proposes an efficient online liveness fault detection mechanism for cloud systems that integrates existing detectors to quickly detect faults. We compared the fault detection efficiency of the proposed mechanism with those of counterpart mechanisms. According to the results, relative to system layer heartbeating without any auxiliary detection mechanism, our proposed mechanism had a 70.3 percent shorter fault detection time.

Today, vehicles have been an essential part of our daily life. According to survey, one-third drivers admit they have left their vehicle while it running, which makes the vehicle an easy target for theft. In this paper, we propose a novel driver identification method with wearable device. This approach can be used in continuous authentication to offer a greater degree of multilevel protection. Our proposed method is based on the hypothesis that a driver has a specific habit to drive a vehicle; and such behavioral biometrics can be captured from the wearable device. In order to validating this hypothesis, we have used the wireless sensor modules to collect driver's behavioral information. Then, the experimental results indicate that the proposed approach is feasible.

Today, vehicles have been an essential part of our daily life. Existing vehicle security systems rely primarily on lock devices, alarm systems or fingerprints as forms of protection. A non-intrusive driver authentication mechanism could be incorporated into existing vehicle security system to offer a greater degree of multilevel protection. In this paper, we propose a novel non-intrusive authentication mechanism based on dynamics of driver's upper body joint angles. This new approach is based on the hypothesis that a driver has a specific habit to drive a vehicle; and such behavioral biometrics can be captured from the motion capture system. We design an authentication mechanism that adopted 40 new features transformed from the information of the driver's upper body joints. To validate this hypothesis, we have used iPi motion capture system to collect driver's behavioral biometrics. The experimental results show that the proposed approach has an equal error rate about 13%.

In this study, we propose to adopt histogram features obtained from smartphone sensors for building authentication models, which could be used to nonintrusively authenticate smartphone users in varying operating scenarios (e.g. standing and sitting) when engaged in using stationary apps. We adopted two smartphone sensors, namely touchscreen and orientation sensor, to evaluate their feasibility. Consequently, sixteen touch-based features and thirty-three orientation-based features were separately used to construct two authentication models. To evaluate the performance of two constructed models, thirty-five subjects joined for collecting experimental data in two operating scenarios, standing and sitting. The experimental results showed that the equal error rate (EER) of touch-based model was approximately 6.56% with features extracted from ten flick touch gestures and reduced to approximately 3.05% with sixty flick touch gestures. For orientation-based model, the EERs were approximately 10.27% and 7.07%, separately. The results showed that the histogram features of the adopted two sensors are feasible for authentication purpose. Specially, this study further discusses the phenomenon of multiple behavioral pattern over the adopted two sensors caused among different operating scenarios, such as standing and sitting.

With the integrity of the information in financial reports being questioned and the shift towards more rapid financial reporting, the auditing profession has found that Continuous Assurance is an effective means of facilitating early detection of fraudulent financial reports. However, according to recent surveys, Continuous Assurance has not been widely applied to date. This fact motivates us to investigate if state-of-the-art IT technologies are capable of supporting Continuous Assurance. The contribution of this study is threefold. First, we develop an ISO/IEC 9126-based Continuous Assurance evaluation framework with six technical criteria. Second, based on the proposed framework, we review two (real-time) IT technologies, namely the Embedded Audit Module (EAM) and the Interceptor mechanism, and explore the feasibility of using them to implement real-time Continuous Assurance (CA). Overall, the interceptor approach outperforms the EAM approach, although neither approach satisfies all of the framework's technical criteria. Third, we find that using the interceptor mechanism in the middleware layer, rather than in other layers, improves the implementation of a real-time auditing interceptor. In light of the proposed evaluation framework, we consider the future development of a middleware interceptor technology that can be used to firmly establish a real-time Continuous Assurance framework.

Web services has become popular in modern distributed applications, and the SOAP technology currently is the most used in Web services. Recent middleware research works widely use interception approach for many problem domains, for example fault tolerance, continuous audit {CA), security etc. Instead of providing a portable interceptor as CORBA does, SOAP 1.2 provides an intermediary mechanism. Due to backward compatibility issue, we found intermediary mechanism is not a feasible solution for interception. Furthermore, our use case analysis found that CORBA Portable Interceptor functionality does not fulfill all requirements of continuous audit. This motivates us to develop a new portable interceptor mechanism (PIM) on SOAP for CA. In this paper, we propose a PIM on SOAP to meet the interception requirements for Web services. Our PIM includes portable interceptor management in SOAP engine and portable interceptor interface definitions.

The simple object access protocol (SOAP) is recognized as a more promising middleware for electronic commerce applications among other leading candidates such as CORBA. Many recent polls reveal however that security and reliability issues are major concerns that discourage people from engaging in electronic commerce transactions. We note that these issues are not adequately addressed in the current standard, i.e., SOAP 1.2. Active replication is a common approach to building readily available and highly reliable distributed software applications. The redundant nested invocation (RNI) problem arises when servers in a replicated group issues nested invocations to other server groups in response to a client invocation. Automatic suppression of RNI from active group is always a desirable function, yet this function usually requires careful if not complex design. The design complexity increases if the system involves multithreading implementation. Existing solutions either solve RNI problem for single-threading cases or solve multithreading cases at the expense of portability. In this work, we propose a mechanism to perform auto-suppression of redundant nested invocation on an active replication fault tolerant Web service. Our approach is portable so that the Web service running on our platform is able to interact with any other SOAP applications. Our preliminary experiments show that the proposed auto-suppression mechanism is efficient in most cases.

Zwass (1996) suggested that middleware and message service is one of the five fundamental technologies used to realize electronic commerce (EC). The simple object access protocol (SOAP) is recognized as a more promising middleware for EC applications among other leading candidates such as CORBA. Many recent polls reveal however that security and reliability issues are major concerns that discourage people from engaging in EC transactions. We notice that the fault-tolerance issue is somewhat neglected in the current standard, i.e., SOAP 1.1. We therefore propose a fault tolerant Web service called fault-tolerant SOAP or FT-SOAP through which Web services can be built with higher resilience to failure. FT-SOAP is based on our previous experience with an object fault tolerant service (OFS) [Liang, D. et al., (1999)] and OMG's fault tolerant CORBA (FT-CORBA). There are many architectural differences between SOAP and CORBA. One of the major contributions of this work is to discuss the impact on FT-SOAP design due to these architectural differences. Our experience shows that Web services built on a SOAP framework enjoy higher flexibility as opposed to those built on CORBA. We also point out the limitations of the current feature sets of SOAP 1.1. We believe our experience is valuable not only to the fault-tolerance community, but also to other communities as well, in particular, to those who are familiar with the CORBA platform.

Active replication is a common approach to building highly available and reliable distributed software applications. The redundant nested invocation (RNI) problem arises when servers in a replicated group issues nested invocations to other server groups in response to a client invocation. Automatic suppression of RNI is always a desirable solution, yet it is usually a difficult design issue. If the system has multithreading (MT) support, the difficulties of implementation increase dramatically. Intuitively, to design a deterministic thread execution control mechanism is a possible approach. Unfortunately, some modern operating systems implement threads on the kernel level for execution fairness. For the kernel thread case, modification on thread control implies modifying the operating system kernel. This approach loses system portability which is one of the important requirements of CORBA or middleware. In this work, we propose a mechanism to perform the auto-suppression of redundant nested invocation in an active replication fault-tolerant (FT) CORBA system. Besides the mechanism design, we discuss the design correctness semantic and the correctness proof of our design.

Active replication is a common approach to building highly available and reliable distributed software applications. The redundant nested invocation (RNI) problem arises when servers in a replicated group issue nested invocations to another server group in response to a client invocation. Automatic suppression of RNI is always a desirable solution, yet it is usually a difficult design issue. In this research, we propose a new determinism reference model based on accomplishing the verification process in a more systematic manner The proposed determinism reference model consists of four levels, namely: ideal determinism, isomorphic determinism, similar determinism, and non-determinism. We consider a class of multi-threading CORBA environments to demonstrate the power of the proposed determinism reference model.

Performance analysis of concurrent executions in parallel systems has been recognized as a challenging problem. The aim of this research is to study approximate but efficient solution techniques for this problem. We model the structure of a parallel machine and the structure of the jobs executing on such a system. We investigate rich classes of jobs, which can be expressed by series, parallel-and, parallel-or, and probabilistic-fork. We propose an efficient performance prediction method for these classes of jobs running on a parallel environment which is modeled by a standard queueing network model. The proposed prediction method is computationally efficient, it has polynomial complexity in both time and space. The time complexity is O(C/sup 2/N/sup 2/K) and the space complexity is O(C/sup 2/N/sup 2/K), where C is the number of job classes in the system, the number of tasks in each job class is O(N), and K is the number of service centers in the queueing model. The accuracy of the approximate solution is validated via simulation.

The distributed object oriented computing model is the next logical step to develop distributed applications. In recent years, several object models have been proposed, such as COM/DCOM, CORBA, and JAVA Bean etc. In CORBA, which was announced by OMG, object request broker is a software bus to connect applications and object components. In addition, multi threaded programming is a well known technique to improve the performance of applications. In a CORBA environment, clients can invoke the remote objects that are shared. If those objects are single threaded it will affect system performance in large distributed applications. We describe in detail the design and implementation of multi threaded object request broker based on CORBA. Our ORB was implemented atop Windows NT and underlying TCP protocol. Finally, we compare our system's performance with IONA's Orbix, which is a well known commercial product, in both one-way and two-way request.

The concept of transactions is not only indispensable in database applications, but also useful in building robust software for mission critical applications. The paper presents an implementation of the Object Transaction Service (OTS) based on CORBA 2.0 specification. Transactional applications developed with the support of our OTS implementation are able to assure the ACID properties even in the presence of node crashes, software system failures and process hangs. The preliminary results obtained from the experiments on Sun workstations with Orbix 1.3 show that the overhead due to the OTS service is satisfactory for most applications.

There are more and more COSS (Common Object Service Specifications) on CORBA (Common Object Request Broker Architecture) announced by the OMG (Object Management Group), but no common specification about fault-tolerance exists. We propose a "warm stand-by" replication approach. When an object (primary object) is invoked, it will invoke a secondary object, and the primary object will log the messages and checkpoint the state to the secondary object periodically. If the primary object fails, the secondary object can take over by way of a client executing a few operations to change the secondary object's mode to primary. Following the style of COSS, we define four interfaces and provide class implementations that can help programmers write programs with fault-tolerant capability. The whole model has been implemented on Orbix, which is a full implementation of CORBA specification.

A computation task running in distributed systems can be represented as a directed graph H(V, E) whose vertices and edges may fail with known probabilities. In this paper, we introduce a reliability measure, called the distributed task reliability, to model the reliability of such computation tasks. The distributed task reliability is defined as the probability that the task can be successfully executed. Due to the and-fork/and-join constraint, the traditional network reliability problem is a special case of the distributed task reliability problem, where the former is known to be NP-hard in general graphs. For two-terminal and–or series-parallel (AOSP) graphs, the distributed task reliability can be computed in polynomial time. We consider a graph Hk(Vˆ, Eˆ), named a k-replicated and–or series-parallel (RAOSP) graph, which is obtained from an AOSP graph H(V, E) by adding (k - 1) replications to each vertex and adding proper edges between two vertices. It can be shown that the RAOSP graphs are not AOSP graphs; thus, the existing polynomial algorithm does not apply. Previously, only exponential time algorithms as used in general graphs are known for computing the reliability of Hk(Vˆ, Eˆ). In this paper, we present a linear time algorithm with O(K(|V| + |E|)) complexity to evaluate the reliability of the graph Hk(Vˆ, Eˆ), where K = max{k222k, 23k}. © 1997 John Wiley & Sons, Inc.

Increasing the parallelism in transaction processing and maintaining data consistency appear to be two conflicting goals in designing distributed database systems (DDBSs). This problem is especially difficult if the DDBS is serving long-lived transactions (LLTs). A special case of LLTs, called sagas, has been introduced that addresses this problem. A DDBS with sagas provides high parallelism to transactions by allowing sagas to release their locks as early as possible. However, it is also subject to an overhead, due to the efforts needed to restore data consistency in the case of failure. We conduct a series of simulation studies to compare the performance of LLT systems with and without saga implementation in a faulty environment. The studies show that saga systems outperform their nonsaga counterparts under most of conditions, including heavy failure cases. We thus propose an analytical queuing model to investigate the performance behavior of saga systems. The development of this analytical model assists us to quantitatively study the performance penalty of a saga implementation due to the failure recovery overhead. Furthermore, the analytical solution can be used by system administrators to fine-tune the performance of a saga system. This analytical model captures the primary aspects of a saga system, namely data locking, resource contention and failure recovery. Due to the complicated nature of the analytical modeling, we solve the model approximately for various performance metrics using decomposition methods, and validate the accuracy of the analytical results via simulations.

A model is given for developing application with fault-tolerance requirements and real-time constraints. Applications in this model are specified using computation graphs, in which vertices represent tasks and arcs represent precedence constraints. Tasks are replicated to provide required fault tolerance and ensure that a real-time application will meet its deadlines despite failures. The authors develop an analytical model to calculate the probability of successful execution of applications with task replications. They propose an efficient algorithm for the analysis of applications that are composed of subgraphs, each of which has a single source and a single sink. The results of the analysis can be used with information from allocation/scheduling to develop applications with desired timing and fault-tolerance requirements.>