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121.
High-ranking officers require advanced military education in war tactics for future combat. However, line officers rarely have time to take such courses on campus. The conventional solution to this problem used to take the inefficient correspondence courses. Whereas Internet technologies progress, online course is the current trend for military training. However, the question is what distance learning methodology best suits such a proprietary learning purpose.This study presents a sequential process of developing distance learning courses in advanced military education. Further, the Petri-Net analytical approach is adopted to discover the essential interaction requirements of advanced military education delivered via Internet. This study developed a systematic method for designing e-learning systems according to specific requirements of target courses. The proposed approach starts by comparing on-campus programs with the existing e-learning systems to identify the steps required to transform the program into an e-learning system. After first outlining the pedagogy of the on-campus program, its proposed teaching flow through the Internet is then sketched. Finally, the Petri-Net model was used for in-depth analysis of the stages affecting the learning curve of the line office taking e-learning courses. The example of a “Joint Operations” AME course elaborated the presented approach. An e-learning system prototype was also designed accordingly. Lastly, an experiment was conducted to verify the efficiency of the presented approach. 相似文献
122.
Performance of DS SS system under on-off wideband jamming 总被引:1,自引:0,他引:1
Xiang Gui Tung Sang Ng 《Electronics letters》1997,33(7):557-559
A performance analysis of a direct sequence spread spectrum (DS SS) system under a periodic on-off wideband jammer is presented. Closed-form results of system bit error rate (BER) are derived for all possible cases of jammer duty cycle 相似文献
123.
This paper reports on fabrication and characterization of a new electrostatic microactuator that achieves out-of-plane multi-axis motion with a single silicon device layer. The multi-axis motion with the simple actuator design is possible by incorporating a three-dimensional (3-D) polydimethylsiloxane (PDMS) microstructure. This paper develops a new device processing method named "Soft-Lithographic Lift-Off and Grafting (SLLOG)" to fabricate the previously designed PDMS-on-silicon hybrid actuator structure. SLLOG is a low-temperature (less than 150/spl deg/C) process that allows replica molded PDMS microstructures to be integrated in silicon micromachined device patterns. The fabricated actuator is characterized using laser vibrometry. The experimental results demonstrate actuation motions achieved in three independent axes with fast dynamic response reaching a bandwidth of about 5 kHz. The fabricated PDMS-on-silicon actuator yields a vertical displacement up to 5 /spl mu/m and rotational motions with a 0.6-/spl deg/ tilting angle at a 40-V peak-to-peak ac actuation voltage. 相似文献
124.
This study investigated changes in the marginal adaptation and surface morphology of Ketac-Silver and Chelon-Silver glass-current cements over time. Dispersalloy amalgam was used as a control. Contralateral pairs of carious primary molars were restored with the test materials and amalgam. Clinical evaluations were scheduled at 12, 18, and 24 months after placement. Gold-plated replicas of the restorations were observed with scanning electron microscopy. Fractures and cracks in the surface of the Dispersalloy and Chelon-Silver increased the surface roughness; however, the damage was superficial and self-limiting in the Dispersalloy restorations, while in Chelon-Silver the fractures caused the material to break down in layers. A substantial quantity of pores, usually smaller than 50 microns in diameter, were observed throughout the surface of the Chelon-Silver restorations. The pores in the surface of Ketac-Silver were fewer and smaller. The incidence of cavomarginal breakdown increased with time. Chelon-Silver restorations had a higher rate of cavomarginal breakdown than did Ketac-Silver and Dispersalloy restorations up to 18 months. However, there was no statistically significant difference in the marginal adaptation of the three groups at 24 months. 相似文献
125.
126.
Ong Lin Seng Chan Yiu Wing Gerald Seet 《International Journal of Pressure Vessels and Piping》1989,38(5):369-383
The elastic analysis of a dent on a pressurised cylinder is investigated. The predetermined shapes of the dent are grouped into three categories according to the physical geometry of the dent width, namely the local dent, the short dent, and the long dent. The induced bending stresses associated with the dent are evaluated using Sanders's non-linear shell theory. The geometry of the dent is treated as an initial geometric imperfection and incorporated in the expressions of strain. The non-linear cylindrical shell equations thus obtained are linearised and then solved by a Fourier series expansion technique. Comparison of theoretical results with the finite element approach is made for a pipe of assumed dimensions and pressure. Good agreement of the results is observed. The analytical approach of this paper is suitable for pipe or cylinder with a dent depth of up to five times the wall thickness. 相似文献
127.
I.-Chung Tung 《Polymer Bulletin》1991,25(2):253-255
Summary The development of crazes of linear amorphous polymers competes with the occurrence of general yielding in the plastic zone in tensile deformation. For toughened semi-ductile linear amorphous polymers, general yielding in the plastic zone is suppressed by the development of crazes. This suppresion prevents the crack tip from being blunt. Therefore it is recommended that the blunting line be neglected for the evaluation of Jic. For semi-ductile linear amorphous polymers, general yielding in the plastic zone takes place and blunts the crack tip. Thus the blunting line cannot be neglected for the evaluation of Jic. 相似文献
128.
129.
P. K. A. Yiu D. M. Brotton 《International journal for numerical methods in engineering》1986,23(12):2287-2301
This paper presents a general finite difference equation for the determination of beam bending moments. The scope of its application to the solution of cable-assisted bridge problems is discussed. Its derivation and relation to previous difference formulations is explained. It is found that some previous formulations can be conveniently represented by the proposed general difference equation through the variation of a general difference coefficient. The accuracy of the proposed equation is illustrated with numerical examples. 相似文献
130.
An oligonucleotide-peptide conjugate, having dual binding capability for a designated RNA, was designed. The peptide portion of the conjugate interacts with a folded domain in the RNA, whereas the oligonucleotide portion hybridizes with a nearby single-stranded region in the RNA. The dual specificity was proven in a model HIV-1 TAR RNA system using an RNase H cleavage assay to assess antisense binding to this RNA. The peptide portion of the conjugate was shown to confer increased specificity on the oligonucleotide. 相似文献