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91.
本文通过针对大学生这一消费群体的生活方式进行研究:族群定位、心理与诉求嗜好的生活观念、购物与理财的消费观念、媒体与偶像偏好的传媒观念,来构架不同消费者生活方式,借以细分出不同的消费群体,可以让企业在选择目标时。对他们的偏好有更深入的了解,并规划针对性特征进行产品定位,选择针对性的营销通路和媒体广告。这样才能抓住消费者的行为动态来掌握未来市场的走向,促进品牌长久发展。 相似文献
92.
Biomechanical evaluation of bike power saver 总被引:1,自引:0,他引:1
Shan G 《Applied ergonomics》2008,39(1):37-45
Bike power saver (BPS) is a new product that claims to change the angle of pedaling forces and reduce applied power dead range (Chic Sheng Industrial Co., Ltd, Taiwan, China). In order to determine its effectiveness, we quantified how BPS operates through a 3D kinematical study and electromyography (EMG) analysis of leg muscles during pedaling. Ten kinesiology students participated in this study. A 3D motion capture system consisting of nine high-speed cameras (VICON v8i, a capture rate of 120 frames/s) was used to collect the total body and pedal motion with and without BPS at statically determined low, middle and high intensity cycling levels. The short-time test (14s) was applied to all intensity levels while the long-time test (30 min) was applied only to the low wattage level. Wireless EMG was synchronized with the 3D motion capture system to monitor the right and left tibialis anterior, gastrocnemius, quadriceps and hamstring. The results revealed that BPS did not alter hip and knee movement significantly (p>0.05), but it did vary ankle movement. BPS caused a movement change in the pedals, and consequently induced instability in ankle control. The altered pedal movement led to an increase in activity level and presumably also energy expenditure for dominant muscles, resulting in a faster fatigue process. From these data, it is likely that the BPS actually requires more effort than a standard bike. 相似文献
93.
郑思孝 《核技术(英文版)》1994,(2)
ACOMPLEX-TYPEFOCUSSEDMAGNETRONFORSPUTTERING¥ZhengSixiao(郑思孝)(InstituteofNuclearScienceandTechnology,SichuanUniversity,Chengdu... 相似文献
94.
无线传感器网络(WSN)由许多传感器节点组成,这些传感器节点为了降低能量消耗会周期性地在醒与睡2种模式下进行切换。在异步WSN中,发送节点往往要等接收节点醒来才能进行数据转发,为了缩短该等待时延,发送节点选择多个节点作为候选转发节点,由于任何候选转发节点都有可能进行数据路由,使得邻居节点评估和候选转发节点选择对网络性能产生较大影响。为了更好地进行节点评估与选择,提出一种基于层次分析法(AHP)和模糊推理系统(FIS)的WSN路由算法DAF。将剩余能量、距离和角度作为评估准则,利用AHP确定评估准则的权重,通过FIS动态构建AHP中的成对比较矩阵,并根据该矩阵动态计算出邻居节点的评分,按评分高低选择候选转发节点。实验结果表明,在改变节点数量、睡眠时长和通信半径的对比测试中,DAF在生命周期、能量消耗和平均冗余传输性能方面均优于ORW和ORR算法。 相似文献
95.
96.
M Sedighi P Monshi J Joudaki 《Fatigue & Fracture of Engineering Materials & Structures》2017,40(3):412-422
Equal‐channel angular rolling (ECAR) is a continuous severe plastic deformation process. In this process, severe shear strains apply to the sheet. This strain increases the yield or ultimate strength of sheet without significant change in sheet dimension. In this paper, the effect of ECAR process on mechanical properties and fatigue life of manufactured sheets will be studied. Four AA5083 samples have been prepared and annealed for obtaining stress‐free samples. Three samples have been rolled by the ECAR process with one, two and three passes of rolling, respectively. Mechanical tests including tensile test, hardness and axial fatigue tests have been carried out on prepared samples. Fatigue tests have been implemented according to a strain‐based approach with a constant strain ratio equal to 0.75 and 0.5 Hz frequency of loading. All of the tests have been carried out in controlled laboratory conditions. Results show that the ultimate tensile strength of samples increases with increasing the pass of rolling. Also, the maximum elongation of samples decreases. Maximum elongation was 17% in annealed samples, while it decreases to 10% in samples with three passes of rolling. The hardness of samples has been measured, and the results show an increase in hardness for a higher pass of the ECAR process. Fatigue test results show that fatigue life of AA5083 samples decreases in manufactured sheets of the ECAR process. Also, cyclic softening has been observed in the ECARed sample. The fracture surfaces of samples after fatigue test have been observed with a scanning electron microscope. A comparison of fracture surfaces confirms that the crack growth was intergranular in annealed samples while it changes in ECARed samples to transgranular. 相似文献
97.
Influence of residual thermal stresses on fatigue crack growth life of discontinuous reinforcements in metal matrix composites 下载免费PDF全文
The fatigue life prediction model based on crack propagation from micro-structural features is derived and presented for planar and randomly oriented Discontinuous Reinforced Metal Matrix Composites (DRMMCs). The model contains the influence of micro-structural properties such as aspect ratio, volume fraction of particle/fibre and constraint between particle and the matrix. The effect of residual thermal stresses generated within the matrix during development of composite is considered. The particle/fibre plays a dominant role in the development of the cyclic plastic zone size ahead of the crack tip; moreover, it enhances the cyclic plastic deformation characteristics of DRMMC. The theoretical model-based evaluations for low cycle fatigue in DRMMCs are within the proximity of the experimental results. 相似文献
98.
Electric vehicles (EVs) acknowledged as potential means of transportation tools in the near future are widely accepted as the development trend of automobile industry due to its environment protection and fuel energy saving properties. As a product containing new technologies and concepts with little market experience and consumer identification, studying its life cycle operation modes will help to figure out an optimal approach to conduct EVs manufacturing and service. The two common operation modes, lease and sale of EVs, have their own advantages and weaknesses under different scenarios and consumer psychological status. Research and comparisons on the function, cost and value of two operation modes in full life cycle will simulate the rapid development of EVs forming a mature and dynamic operation mechanism. This paper utilised approaches in value engineering, putting forward customer requirements and technical elements of EV lease and sale based on quality assessment and customer-perceived value, proposing the metric method of function and cost coefficient by mathematical modelling, and conducting value coefficient analysis and comparison based on customer’s risk aversion psychology. An illustrative example raised for studying operation mode of three different kinds of EVs based on the analysis of value coefficient, providing guideline for manufacturer and servicers of EVs. 相似文献
99.
100.
In this study, the very high cycle fatigue (VHCF) properties of 7050-T7451 aluminum alloy and its friction stir welding (FSW) butt welds have been investigated. The results show that the failure of FSW joints still occurs at 7.0 × 108 cycles. The fatigue properties of the FSW joints are superior to those of the base material, especially in the super long life regime. Most fatigue cracks initiate at the thermo-mechanically affected zone and heat affected zone on the advancing side of the FSW joints, and the susceptibility of these zones to fatigue is attributed to the metallurgical heterogeneity. 相似文献