A fuzzy trust evaluation method for knowledge sharing in virtual enterprises

The success of virtual enterprises (VEs) depends on the effective sharing of related resources between various enterprises or workers who perform related activities. Specifically, VE success hinges on the integration and sharing of information and knowledge. Trust is an important facilitator of knowledge sharing. However, the trustworthiness of a peer is a vague concept that is dynamic and that often shifts over time or with environmental changes. This study designs a trust-based knowledge-sharing model based on characteristics of VEs and the knowledge structure model to express knowledge associated with VE activities. Subsequently, the factors that affect the trust evaluation are identified based on the characteristics of trust and VEs. Finally, this study develops a knowledge sharing, decision-making framework in which a fuzzy trust evaluation method for sharing knowledge is proposed based on VE activities and the interactions among workers in allied enterprises. The method consists of three sub-methods, including an activity correlation evaluation method, a current trust evaluation method, and an integral trust evaluation method. Under the premises of secure VE knowledge and reasonable access authorization, the proposed knowledge-sharing method provides the trust level between a knowledge-requesting enterprise and a knowledge-supplying enterprise to improve the willingness of the latter to share more valuable knowledge, ultimately increasing the efficiency and competitiveness of VEs.     

A trust degree based access control in grid environments

The purpose of grid computing is to enable coordinated resource sharing and support cooperative work between different domains in dynamic grid environments. In order to protect each participant’s privilege and security, a secure and efficient access control is essential. This paper presents a new approach of access mechanism based on trust relationships across domains. A new calculation method of trust in grid is proposed and the difference between intro-domain trust and inter-domain trust is analyzed. In addition, a novel access control framework combined with trust degree is given from this proposal. It is shown to be adaptive for both intro-domain and inter-domain conditions. Hence, a prototype system based on the proposed model is introduced; furthermore, it has been shown as a dynamic and fine-granularity access control method through performance analyses and has also been demonstrated as a suitable system for grid environments.     

Knowledge sharing in virtual enterprises via an ontology-based access control approach

Collaborating throughout a product life cycle via virtual enterprise (VE) is one of the most promising strategies for enhancing global competitiveness. Efficient and secure knowledge sharing is critical to the success of a VE. This study presents a novel approach, model and technology for knowledge access control and sharing across enterprises. First, this study proposes an ontology-based knowledge sharing model and a multiple-layer knowledge representation framework on which a knowledge access control model for knowledge sharing in a VE is proposed. In the proposed model, user authorizations permitting access to knowledge in a VE are classified into two levels: (1) basic privileges and (2) extended privileges. The former is evaluated from four dimensions, i.e. who, what, when and where, while the latter is determined by considering how three domain ontologies, i.e., product, organization and activity, are related. This study then develops a knowledge access control policy (KACP) language model which is used to identify the knowledge access control and sharing rules of a VE and all its enterprise members. The knowledge access control model proposed in this study can facilitate VE Knowledge management and sharing across enterprises, enhance knowledge sharing security and flexibility and regulate knowledge sharing to expeditiously reflect changes in the business environment.     

How to facilitate inter-organizational knowledge sharing: The impact of trust

In this era of the network economy, inter-organizational knowledge sharing is one key driving force required to streamline value chain activities and maximize operational benefits. Knowledge sharing can be realized when the involved business partners successfully develop trust and build long-term partnerships. In this study, a model of knowledge sharing across the supply chain is constructed. Factors such as shared goals, social relational embeddedness, and influence strategy are investigated to determine whether they act as major driving forces to develop inter-organizational trust among the various supply chain members. The survey is based on 226 managers located in major industrial parks in Taiwan; the results suggest that trust is enforced when organizations develop shared goals, form social relational embeddedness, and initiate influence strategies. In addition, inter-organizational trust leads to better inter-organizational collaboration and knowledge sharing. Theoretical and practical implications are also discussed.     

Trust and conflict within virtual inter-organizational alliances: a framework for facilitating knowledge sharing

Trust and conflict are inherent issues of any organizational arrangement and central for knowledge sharing; yet they have received limited attention in the literature. In this paper, we undertake an investigation of both phenomena within the context of virtual alliances. A generic framework for understanding the dynamics of trust and conflict within the context of virtual inter-organizational arrangements is presented, followed by an examination of three distinct structural forms of virtual alliances, and strategies for generating trust and minimizing dysfunctional conflict. The paper concludes with an identification of avenues for further research.     

A decision support system assessing the trust level in supply chains based on information sharing dimensions

Assessing customer trust in suppliers with regards to its influencing factors is an important open issue in supply chain management literature. In this paper, a customer trust index is designed as the trust level arising from the information sharing degree and quality, related to the information shared by a supplier with his customer. The customer trust level is evaluated using a fuzzy decision support system integrating information sharing dimensions. The core is a rule-based system designed using the results of questionnaires and interviews with supply chain experts. Several tests were generated in order to analyze the impact of the different information sharing attributes on the customer trust index. The developed approach is then applied to a real supply chain from the textile industry. Results show large differences of weight and impact between the different information-related factors that build the customer trust index. It is also shown that the proposed system has an important role in ensuring the objectivity of the trust assessment process and in helping decision makers evaluate their business partners.     

Social capital and individual motivations on knowledge sharing: Participant involvement as a moderator

The Internet is a communication channel that allows individuals to share information and knowledge. However, it is not obvious why individuals share knowledge with strangers for no apparent benefit. What are the critical factors influencing such behavior? To attempt to understand this paradox, we combined the theories of social capital and individual motivation to investigate the factors influencing knowledge sharing behavior in a virtual community, applying a participant involvement concept to analyze the moderating effects of individual motivation on knowledge sharing behavior. By analyzing the results of a survey using a questionnaire, we found that altruism, identification, reciprocity, and shared language had a significant and positive effect on knowledge sharing. Reputation, social interaction, and trust had positive effects on the quality, but not the quantity, of shared knowledge. Participant involvement had a moderating effect on the relationship of altruism and the quantity of shared knowledge. Theoretical and managerial implications are discussed.     

Adaptive piggybacking: a novel technique for data sharing in video-on-demand storage servers

Recent technology advances have made multimedia on-demand services, such as home entertainment and home-shopping, important to the consumer market. One of the most challenging aspects of this type of service is providing access either instantaneously or within a small and reasonable latency upon request. We consider improvements in the performance of multimedia storage servers through data sharing between requests for popular objects, assuming that the I/O bandwidth is the critical resource in the system. We discuss a novel approach to data sharing, termed adaptive piggybacking, which can be used to reduce the aggregate I/O demand on the multimedia storage server and thus reduce latency for servicing new requests.     

A novel approach to digital image watermarking based on a generalized secret sharing scheme

In the digital image watermarking community, the problem of joint ownership has not been adequately addressed. This paper proposes a novel algorithm that makes use of a generalized secret sharing scheme in cryptography to address this problem. Given that multiple owners create an image jointly, distinct keys are given to only an authorized group of owners so that only when all the members in the group present their keys can the ownership of the image be verified. Any owner alone cannot verify the image ownership. In addition, experimental results show that the proposed algorithm has the desired properties such as invisibility, reliable detection, and robustness against a wide range of image-processing operations.     

Role-Based Access Control in a Data Grid Using the Storage Resource Broker and Shibboleth

In this paper, we propose a role-based access control (RBAC) system for data resources in the Storage Resource Broker (SRB). The SRB is a Data Grid management system, which can integrate heterogeneous data resources of virtual organizations (VOs). The SRB stores the access control information of individual users in the Metadata Catalog (MCAT) database. However, because of the specific MCAT schema structure, this information can only be used by the SRB applications. If VOs also have many non-SRB applications, each with its own storage format for user access control information, it creates a scalability problem with regard to administration. To solve this problem, we developed a RBAC system with Shibboleth, which is an attribute authorization service currently being used in many Grid environments. Thus, the administration overhead is reduced because the role privileges of individual users are now managed by Shibboleth, not by MCAT or applications. In addition, access control policies need to be specified and managed across multiple VOs. For the specification of access control policies, we used the Core and Hierarchical RBAC profile of the eXtensible Access Control Markup Language (XACML); and for distributed administration of those policies, we used the Object, Metadata and Artifacts Registry (OMAR). OMAR is based on the e-business eXtensible Markup Language (ebXML) registry specifications developed to achieve interoperable registries and repositories. Our RBAC system provides scalable and fine-grain access control and allows privacy protection. Performance analysis shows that our system adds only a small overhead to the existing security infrastructure of the SRB.     

Personal information leakage detection method using the inference-based access control model on the Android platform

The web services used on desktop can be accessed through a smartphone due to the development of smart devices. As the usage of smartphones increases, the importance of personal information security inside the smartphone is emphasized. The openness features of Android platform make a lot easier to develop an application and also deploying malicious codes into application is an easy task for hackers. The security practices are also growing rapidly as the number of malicious code increases exponentially. According to these circumstances, new methods for detecting and protecting the behavior of leaked personal information are needed to manage the personal information within a smartphone.In this paper, we study the permission access category in order to detect the malicious code, which discloses the personal information on Android environment such as equipment and location information, address book and messages, and solve the problem related to Resource access of Random Access Control method in conventional Android file system to detect the new malware or malicious code via the context ontology reasoning of permission access and API resource information which the personal information are leaked through. Then we propose an inference-based access control model, which can be enabled to access the proactive security. There is more improvement accuracy than existing malicious detecting techniques and effectiveness of access control model is verified through the proposal of inference-based access control model.     

A study on visual sensor network cross-layer resource allocation using quality-based criteria and metaheuristic optimization algorithms

Visual sensor networks (VSNs) consist of spatially distributed video cameras that are capable of compressing and transmitting the video sequences they acquire. We consider a direct-sequence code division multiple access (DS-CDMA) VSN, where each node has its individual requirements in compression bit rate and energy consumption, depending on the corresponding application and the characteristics of the monitored scene. We study two optimization criteria for the optimal allocation of the source and channel coding rates, which assume discrete values, as well as for the power levels of all nodes, which are continuous, under transmission bit rate constraints. The first criterion minimizes the average distortion of the video received by all nodes, while the second one minimizes the maximum video distortion among all nodes. The resulting mixed integer optimization problems are tackled with a modern optimization algorithm, namely particle swarm optimization (PSO), as well as a hybrid scheme that combines PSO with the deterministic Active-Set optimization method. Extensive experimentation on interference-limited as well as noisy environments offers significant intuition regarding the effectiveness of the considered optimization schemes, indicating the impact of the video sequence characteristics on the joint determination of the transmission parameters of the VSN.     

基于永磁同步电机的新型直接转矩控制策略研究

传统直接转矩控制(Direct Torque Control,DTC)策略在永磁同步电机(Permanent Magnet Synchronous Motor,PMSM)中应用时出现转矩和磁链脉动较大的现象.对此,提出了一种新型DTC策略,将改进后的滑模控制(Sliding Mode Control,SMC)器引入到P...     

基于新型无功和谐波电流检测方法的APF仿真研究

结合基于瞬时无功功率理论的ip-iq检测方法和基于传统功率理论的闭环自适应检测方法两者的优点,设计一种新的检测方法,该方法具有较好的鲁棒性和动态响应速度.同时由于逆变器采用三桥臂电容中点式结构,对其直流侧电压的稳定和上下电容的均压控制作了分析,与无功和谐波电流检测结合起来形成了双闭环结构,进一步增强补偿效果,然后对指令电流的合成和其跟踪控制作了简要阐述.最后利用Matlab/Simulink对系统进行了仿真,验证了该方法的正确性和有效性.     

Real-time continuous ZMP pattern generation of a humanoid robot using an analytic method based on capture point

This paper introduces an analytic method to generate a continuous ZMP pattern based on a capture point (CP). When a target CP is decided in real-time, the pattern generator makes the CP, ZMP, which it is within convex hull of the supporting feet area, and CoM patterns without discontinuity by closed-form solutions for a single step. Therefore, the proposed pattern generation method does not need a ZMP pattern modification, numerical iterations, and future ZMPs. The method is employed to treat applications such as step length change while walking and push recovery during walking in place. Furthermore, since compliant characteristics such as body oscillation appear in the humanoid robot, we introduce a system model, a double inverted pendulum model with flexible joints for the model-based control. Finally, the real-time walking pattern generation method and the walking control scheme are verified by experiments with the humanoid robot HUBO2.