Investigation of waterjet-workpiece interaction

The objective of this research is to develop new knowledge related to the fundamental physical phenomena of waterjet machining of ductile materials, and to use this knowledge to construct a numerical analysis model. The resulting knowledge will enable enhancement of waterjet cutting efficiency. Experimental study of fundamental mechanisms and the acquisition of the data detailing micro and macro scale phenomena which occur during the machining process is carried out. It is shown that the material damage mechanism associated with waterjet machining is erosion cavitation which initiates ultrasonic stress wave propagation in the workpiece. Fatigue, an important element in producing material erosion, is enhanced by this high frequency stress and reduces the material endurance limit. Experimental results validate the existence of these stress waves. The frequency is 3 MHz in the case studies. The acquired information is used to construct a detailed description of the phenomena using finite element numerical modeling and continuum damage mechanics. Numerical results are in good agreement with the experimental results. The resulting models may be used to optimize the jet generation and jet workpiece interaction with particular focus on the improvement of nozzle design, integration of kinetic, chemical, and thermal energies for material shaping, and use of high speed percussive jets. With these new technologies and techniques, enhancement of material machining will be feasible

Investigation of forces in the course of the water jet--work piece interaction

This study is concerned with the dynamic of the interaction between the water jet and the work-piece. The piezoelectric transducer was used to construct an experimental setup. The simultaneous use of the constructed setup and strain gage enables us to validate the experimental procedure. The forces in the impingment zone were measured at different operational conditions. Totally about 400 different combinations of these conditions were tested. It was found that the force is mainly determined by the diameter of the sapphire. The effects of the abrasive size , abrasive flow rate, the diameter of the carbide tube, and the stand-off distance were also determined. The acquired informations will be used to improve the understanding of the mechanism of the jet formation and optimize the condition of cutting

Task scheduling for FMS based on genetic algorithm

A Flexible Manufacturing System (FMS) consisting of p automated guided vehicles (AGV\u27s), m workstations and n tasks is studied. The main problem investigated in this thesis is to find an optimal or suboptimal task scheduling for p AGV\u27s among m workstations to complete n tasks. An efficient approach based on genetic algorithms has been designed and implemented to solve the problem of task scheduling for a FMS. Near-optimal, or even optimal, task scheduling is accomplished by genetic algorithms. Simulation results on the algorithm are also discussed

Critical Stressors Affecting Work Exhaustion of IS Employees in SMEs

The symptoms of stress are becoming more diversified in the IT labor market. IS employees need help in learning how to manage stress so as to reduce the strain in their work-life. The stress issue is also crucial to organizations through controlling stressors to reduce the levels of stress for maintaining better job performance. The purpose of this research is to study the effects of stressors and situational moderators on IS employees’ work exhaustion in the context of small- and medium-sized enterprises (SMEs). In line with the transaction-based model of stress, this research constructs a hypothesized model for testing and verification. Through the empirical survey on the IS employees in SMEs, the results are expected to fill the knowledge gap for IS workplace stress research and to provide references to the practice and the government for managing SMEs’ e-business implementation

The Interplay of Reovirus with Autophagy

Autophagy participates in multiple fundamental physiological processes, including survival, differentiation, development, and cellular homeostasis. It eliminates cytoplasmic protein aggregates and damaged organelles by triggering a series of events: sequestering the protein substrates into double-membrane vesicles, fusing the vesicles with lysosomes, and then degrading the autophagic contents. This degradation pathway is also involved in various disorders, for instance, cancers and infectious diseases. This paper provides an overview of modulation of autophagy in the course of reovirus infection and also the interplay of autophagy and reovirus

Progress in CTEQ-TEA PDF analysis

Recent developments in the CTEQ-TEA global QCD analysis are presented. The parton distribution functions CT10-NNLO are described, constructed by comparing data from many experiments to NNLO approximations of QCD.Comment: 4 pages, 3 figures; contribution to the Proceedings of the XX Workshop on Deep Inelastic Scattering and Related Subjects, Bonn, Germany, 26-30 March, 201

Why do Individuals Continue Using Mobile Payments - A Qualitative Study in China

Many financial and mobile service providers are viewing mobile payment (MP) as a strategic growth area for their business. In order to realize this anticipated growth potential, users must initially adopt and then continue to use MP systems. However, a rich and detailed user perspective of MP continuance behavior is lacking. We address part of this research gap by content-analyzing interview transcripts of 38 MP users. The findings indicate that perceived usefulness and risk, disconfirmation, satisfaction, subjective norm, and habit are important when users making MP continuance decisions