Steady and unsteady modeling of single PEM fuel cell.

Among the various types of fuel cells, the proton exchange membrane (PEM) fuel cell has been considered as a promising choice for automobile. Proper water and thermal management is essential for obtaining high performance from a PEM fuel cell. A steady and unsteady, water and thermal management model was developed to consider the effects of local pressure on the cell performance, pressure drop, open circuit voltage variation with stack temperature, water vapor effects on membrane conductivity. These considerations made the model physically more reasonable and more suitable for various operating conditions. Additionally, this model combined the along-flow-channel model and catalyst layer model, which represent a significant improvement to PEM fuel cell modeling. The model can predict the distributions of a series of important parameters along the flow channel and in the catalyst layer; thus the effects of various operating and design parameters on the fuel cell performance can be investigated easily by a numerical trial-and-error method. The transient performance of the fuel cell can be simulated with this model as well, which is crucial for the fuel cell system control. The modeling results agreed reasonably with the available experimental results from the literature. This model can be used as part of a PEM fuel cell stack or entire system modeling, and represents a very useful engineering tool for the analysis, design and optimization of PEM fuel cell.Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .H83. Source: Masters Abstracts International, Volume: 45-01, page: 0450. Thesis (M.A.Sc.)--University of Windsor (Canada), 2005

Determinants of Information Technology Usage Habit

Habit has been investigated as an antecedent of the information systems usage in a few literatures recent years. But little effort has been found on the determinants of habit itself in the information systems research. Drawing upon the insights from goal-directed behavior, habit/automaticity perspective, and IS continuance model, this paper proposes a research model for understanding the antecedents of the individual information technology usage habit. This study suggest that individual satisfaction, perceived enjoyment and user experience positively influence the strength of usage habit, and that perceived usefulness, confirmation of expectation and perceived enjoyment positively affect satisfaction. The implications are discussed, and contributions of this study are presented

Blockchain-assisted Undisclosed IIoT Vulnerabilities Trusted Sharing Protection with Dynamic Token

With the large-scale deployment of industrial internet of things (IIoT) devices, the number of vulnerabilities that threaten IIoT security is also growing dramatically, including a mass of undisclosed IIoT vulnerabilities that lack mitigation measures. Coordination Vulnerabilities Disclosure (CVD) is one of the most popular vulnerabilities sharing solutions, in which some security workers (SWs) can develop undisclosed vulnerabilities patches together. However, CVD assumes that sharing participants (SWs) are all honest, and thus offering chances for dishonest SWs to leak undisclosed IIoT vulnerabilities. To combat such threats, we propose an Undisclosed IIoT Vulnerabilities Trusted Sharing Protection (UIV-TSP) scheme with dynamic token. In this article, a dynamic token is an implicit access credential for an SW to acquire an undisclosed vulnerability information, which is only held by the system and constantly updated as the SW access. Meanwhile, the latest updated token can be stealthily sneaked into the acquired information as the traceability token. Once the undisclosed vulnerability information leaves the SW host, the embedded self-destruct program will be automatically triggered to prevent leaks since the destination MAC address in the traceability token has changed. To quickly distinguish dishonest SWs, trust mechanism is adopted to evaluate the trust value of SWs. Moreover, we design a blockchain-assisted continuous logs storage method to achieve the tamper-proofing of dynamic token and the transparency of undisclosed IIoT vulnerabilities sharing. The simulation results indicate that our proposed scheme is resilient to suppress dishonest SWs and protect the IoT undisclosed vulnerabilities effectively.Comment: 10 pages,12 figure

GEOMETRY CONSTRUCTION METHOD OF HEX-TRI RECIPROCAL FRAME

In this paper the geometrical characteristics and construction method of hex-tri reciprocal frame are studied. The naming rules of structural units, members and joints of hex-tri reciprocal frame are proposed. Based on the study of relationships between the structural geometrical parameters, the formulas for the joint coordinates of the structural unit are derived, and the calculating method for normalized direction vectors of the unit members is also developed. The geometry construction method of hex-tri reciprocal frame is established in this paper. By this method the whole structure is formed as an assembly of the units arranged in rings about the structural center. The influences of the diameter, the length and the binding length of the member on the rise of hex-tri reciprocal frame are analyzed by an example. If the rise of hex-tri reciprocal frame needs to be specified in the design, the values of the diameter, the length and the binding length of the structural member need to be coordinated to meet the design requirements