Xiaoqing Frank Liu

Analysis of Conflicts among Non-Functional Requirements Using Integrated Analysis of Functional and Non-Functional Requirements

Conflicts among non-functional requirements are often identified subjectively and there is a lack of conflict analysis in practice. Current approaches fail to capture the nature of conflicts among non-functional requirements, which makes the task of conflict resolution difficult. In this paper, a framework has been provided for the analysis of conflicts among non-functional requirements using the integrated analysis of functional and non-functional requirements. The framework identifies and analyzes conflicts based on relationships among quality attributes, functionalities and constraints. Since, poorly structured requirement statements usually result in confusing specifications; we also developed canonical forms for representing non-functional requirements. . The output of our framework is a conflict hierarchy that refines conflicts among non-functional requirements level by level. Finally, a case study is provided in which the proposed framework was applied to analyze and detect conflicts among the non-functional requirements of a search engine.

A Web-based Intelligent Collaborative System for Engineering Design

Design of a modern product is often a very complicated process, which involves groups of designers, manufacturers, suppliers, and customer representatives. Conflicts are unavoidable during collaboration among multiple stakeholders, who have different objectives, requirements, and priorities. Current Web-based collaborative engineering design systems do not support collaborative conflict resolution. In this chapter, we present a Web-based intelligent system that we have developed for collaborative engineering design. It extends a collaborative solid modeling software system by adding an argumentation-based conflict resolution tool, a whiteboard, and a chat utility. We have developed an intelligent computational argumentation model to enable the management of a large scale argumentation network and resolution of conflicts based on argumentation from many participants. A Web-based collaborative engineering design system has been developed based on the above model to resolve conflicts over the Internet by enabling collaborators to select the most favored design alternative in the design argumentation from multiple perspectives. An example of collaborative design of latch mechanism for a solar car using the developed system is presented to show its effectiveness.

Elastic Personalized Nonfunctional Attribute Preference and Trade-off Based Service Selection

For service users to get the best service that meet their requirements, they prefer to personalize their nonfunctional attributes, such as reliability and price. However, the personalization makes it challenging for service providers to completely meet users’ preferences, because they have to deal with conflicting nonfunctional attributes when selecting services for users. With this in mind, users may sometimes want to explicitly specify their trade-offs among nonfunctional attributes to make their preferences known to service providers. In this article, we present a novel service selection method based on fuzzy logic that considers users’ personalized preferences and their trade-offs on nonfunctional attributes during service selection. The method allows users to represent their elastic nonfunctional requirements and associated importance using linguistic terms to specify their personalized trade-off strategies. We present examples showing how the service selection framework is used and a prototype with real-world airline services to evaluate the proposed frameworks application.

Trust-Aware Service Recommendation via Exploiting Social Networks

With the rapid growth in the number of available services, recommending suitable services to users becomes increasingly important. A number of collaborative service recommendation methods based on user experiences have been proposed for this purpose. Most of them adopt the similarity-based Collaborative Filtering (CF) technique, which tends to identify similar users for a target user and recommends to the target user the services preferred by the similar users. However, a user similar to the target user is unnecessarily trustworthy to him/her. Therefore, the results recommended by similarity-based CF are probably unreliable. Moreover, existing service recommendation methods seldom incorporate social trust relationships among service users into service recommendation. In this paper, we propose a collaborative, trust-aware service recommendation method for service-oriented environments with social networks. The method is based on an integration of the user-service relation and the user-user social relation. Experimental results demonstrate that our service recommendation method significantly outperforms conventional similarity-based recommendation and trust-based service recommendation methods.

Computer-automated ergonomic analysis based on motion capture and assembly simulation

This paper describes a method of simulating an assembly operation in a fully immersive virtual environment in order to analyze the postures of workers as they perform assembly operations in aerospace manufacturing. The challenges involved in capturing the movements of humans performing an assembly operation in a real work environment were overcome by developing a marker-based motion capture system and using it in a cave automatic virtual environment (CAVE). The development of the system focuses on real-time human motion capture and automated simulation for ergonomic analysis. Human movements were tracked in a CAVE, with infrared (IR) LEDs mounted on a human body. The captured motion data were used to generate a simulation in real-time and perform an ergonomic analysis in Jack software. The simulation also included the use of Microsoft Kinect as a marker-less human body capture system for the purpose of scaling the digital human model in Jack. The developed system has been demonstrated for human motion capture and ergonomic analysis for the fastening operation of an aircraft fuselage.

Wii remote---based low-cost motion capture for automated assembly simulation

This paper describes the development of a Wii remote (Wiimote)–based low-cost motion capture system and demonstrates its application for automated assembly simulation. Multiple Wiimotes are used to form a vision system to perform motion capture in 3D space. A hybrid algorithm for calibrating a multi-camera stereo vision system has been developed based on Zhang’s and Svoboda’s calibration algorithms. This hybrid algorithm has been evaluated and shown accuracy improvement over Svoboda’s algorithm for motion capture with multiple cameras. The captured motion data are used to automatically generate an assembly simulation of objects represented by CAD models in real time. The Wiimote-based motion capture system is practically attractive because it is inexpensive, wireless, and easily portable. Application examples have been developed for a single vision system with two Wiimotes to track the assembly of a microsatellite prototype frame and for an integrated vision system with four Wiimotes to track the assembly of a bookshelf.

A Hierarchical Object-oriented Functional Modeling Framework for Co-Design of Mechatronic Products

The existing co-design methods of mechatronic products focus on co-design of mechanical and electronic components or co-design of computer hardware and software components. There exist no effective co-design methods for mechanical, electronic, and software components. This article proposes an integrated object-oriented and functional decomposition framework, developed for co-design and co-analysis of product functions, structures, and their mapping relations in a top-down manner. The framework has three operational models: Function Model, Object Model, and Information Flow Model. The function model is implemented as a function tree (FT), which is a hierarchical structure for the functional decomposition and behavioral analysis of the product under functional domain commonly used in classical engineering design. The object model is a high order object model (HOOM) designed for system and component decomposition for analysis and design of the structure of a system and its components under physical domain. The information flow model is a function and object mapping model, which describes and analyzes implementation parameters and mapping relations between FT functions and HOOM objects. These three models are decomposed and constructed level-by-level and side-by-side to form the concurrent and coordinated design paradigm for the product design team. The components of the resulting design are then carefully reviewed and summarized in a design summary and task assignment table by the product design team, and assigned to their respective disciplinary engineers for detail design or implementation according to their attributes. The proposed methodology enables mechanical, electronic, and software engineers to develop mechatronic products concurrently in a seamlessly integrated fashion.

An Efficient Trust Propagation Scheme for Predicting Trustworthiness of Service Providers in Service-Oriented Social Networks

Perception of trustworthiness of service providers is a fundamental need in service selection. Trust propagation has been used to predict trustworthiness of service providers in service-oriented social networks. However, existing trust propagation methods may suffer from a scalability problem, i.e., their computation time is likely too high to be acceptable in practice, especially when they are applied to very large-scale service-oriented social networks. Moreover, they rarely consider the structural properties of social networks to optimize their performance. This paper proposes an efficient trust propagation scheme for predicting trust in service-oriented social networks. It exploits the specific structural properties of social networks and builds an advanced data structure from preprocessing to improve the efficiency of trust propagation. Our scheme can support multiple trust propagation strategies. Experiments show that our scheme is much more efficient than well-known trust propagation methods in trust prediction, while its trust prediction results are as accurate as theirs in service-oriented social networks.

Comparison of Marker-Based and Marker-Less Systems for Low-Cost Human Motion Capture

To generate graphic simulation of human motion, marker-based optical motion capture technology is widely used because of the accuracy and reliability of motion data provided by this technology. However, tracking of human motion without markers is very desirable on the factory floor because the human operator does not need to wear a special suit mounted with markers and there is no physical interference with the manufacturing or assembly operation during the motion tracking. In this paper, we compare marker-based and marker-less motion capture systems. First, the operational principles of these two different types of systems are compared. Then the quality of motion data obtained by a marker-less system using Kinect is compared with that obtained by a marker-based system using Optitrack cameras. The comparison also includes the accuracy of body joint angles and variations in body segment lengths measured by the two different systems. Furthermore, we compare the human motion simulation developed in the Jack digital human modeling software using the data captured by these two systems when a person is performing a fastening operation on a physical mockup of the belly section of an aircraft fuselage.Copyright

An Integrated Calibration Technique for Multi-Camera Vision Systems

This paper presents the integration and evaluation of two popular camera calibration techniques for multi-camera vision system development for motion capture. An integrated calibration technique for multi-camera vision systems has been developed. To demonstrate and evaluate this calibration technique, multiple Wii Remotes (Wiimotes) from Nintendo were used to form a vision system to perform 3D motion capture in real time. This integrated technique is a two-step process: it first calibrates the intrinsic parameters of each camera using Zhang’s algorithm [5] and then calibrates the extrinsic parameters of the cameras together using Svoboda’s algorithm [9]. Computer software has been developed for implementation of the integrated technique, and experiments carried out using this technique to perform motion capture with Wiimotes show a significant improvement in the measurement accuracy over the existing calibration techniques.Copyright