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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
水平井中限流压裂完井设计 总被引:1,自引:0,他引:1
在水平井压裂作业中使用许多完井技术.分段压裂是非常有效的,但是由于它的高成本和高风险,人们很少关注它.已经证实,限流压裂是水平井有效的增产措施之一,其成本和风险是可以接受的. 相似文献
992.
Jong Whan Lee Dong Hee Kwon Jeong Suk Kim Duck Whan Kim Myung Chang Kang Bok Kyu Lim 《Journal of Mechanical Science and Technology》2007,21(2):244-250
This paper presents an investigation on the characteristics of damaged layer in micro-machining by using the ultrahigh-speed
air spindle. The damaged layer in metal cutting is derived from plastic deformation and transformation of metal structure.
In this study, micro-cutting force, surface roughness, and plastic deformation layer according to the variation of machining
conditions were investigated by experiments. The damaged layer was measured using optical microscope for the samples prepared
by metallographic techniques. Its scale was dependent on cutting process parameters, especially feed per tooth. According
to experimental results, it was verified that the thickness of damaged layer was increased with increasing of feed per tooth
and cutting depth, also thickness of damaged layer was reduced in down-milling compared to upmilling during micro-endmilling
operation. 相似文献
993.
Yiping Wang Na Chen Binfeng Yun Yiping Cui 《Photonics Technology Letters, IEEE》2007,19(16):1242-1244
A measurement method has been developed to determine the full-field deformation of a simply supported plane plate under transverse load. The method utilizes strain information provided by a set of four fiber Bragg grating sensors mounted on the plate in a way that all sensors measure strains along one certain direction. The sensors were interrogated using a wavelength swept fiber laser. Utilizing the strain information and the first four terms of Navier solution of simply supported rectangular plate, the necessary parameters for determining the deflection could be computed. By substituting the values of x- and -y- coordinates of each position on the rectangle plate, the full-field deformation information can be obtained. Single-point loading tests were experimentally performed to verify the accuracy of the method. 相似文献
994.
浅谈火灾调查的边缘化趋势 总被引:1,自引:0,他引:1
从火灾调查实际工作状态出发,提出火灾调查存在地位边缘化的趋势,并在分析边缘化趋势原因的基础上提出了相应的对策,供火灾调查同仁探讨。 相似文献
995.
In this study, distribution and history of residual stresses in plaque-like geometries are simulated based on linear thermoviscoelastic
model, which helps to understand the mechanics and evolution of the residual stresses in the injection molding process. The
numerical calculation of direction, combined with the specified boundary conditions. Results show that the stress variation
across the thickness exhibits a high surface tensile value changing to a compressive peak value close to the surface, with
the core region experiencing a parabolic tensile peak. Residual stress distribution throughout the thickness is almost same
along the flowpath and the final residual stresses value near the gate is lower than the value near the end of flowpath. 相似文献
996.
A Subcarriers Allocation Scheme for Cognitive Radio Systems Based on Multi-Carrier Modulation 总被引:1,自引:0,他引:1
Tao Luo Tao Jiang Weidong Xiang Hsiao-Hwa Chen 《Wireless Communications, IEEE Transactions on》2008,7(9):3335-3340
Cognitive radio (CR) is a dynamic spectrum access technology as a solution to spectrum under-utilization problem in some licensed bands. Operating over an exceedingly wide spectrum, CR systems usually adopt multi-carrier modulation (MCM) to implement flexible channelization. Consequently, efficient channel allocation scheme becomes extremely important to an MCM based CR (MCM-CR) system. In this paper, a maximum likelihood detection model is developed to detect the presence and locations of licensed users (LUs) signals in the frequency domain. Performance of the detection model, including the optimal detection region, detection probability and false alarm probability, is analyzed. A one-order two-state Markovian chain model is proposed to predict channel status information. In particular, a novel subcarrier allocation scheme for MCM-CR systems is proposed, taking into account the confidence of channel estimation, quality of services (QoS) of rental users (RUs) and throughput. To validate the analytical results, simulations have been conducted to show effectiveness of the proposed scheme. 相似文献
997.
重构在框架开发中的研究与应用 总被引:2,自引:0,他引:2
框架和应用能够通过重构相互促进,应用和框架的并行开发可以加速框架的开发过程.从框架与应用的中间层,框架与应用的接口的结构和形式等方面,对此过程中的重构方法进行了讨论,提出了几种适应于框架与应用并行开发的重构手段. 相似文献
998.
A method for the time suboptimal control of an industrial manipulator from an initial position and orientation to a final
position and orientation as it moves along a specified path is proposed. Nonlinear system equations that describe the manipulator
motion are linearized at each time step along the path. A method which gives the control inputs (joint angular velocities)
for time suboptimal control of the manipulator is developed. In the formulation, joint angular velocity and acceleration limitations
are also taken into consideration. A six degree of freedom elbow type manipulator is used in numerical examples to verify
the method developed. 相似文献
999.
Nelson Oly Ndubisi 《AI & Society》2007,21(3):287-302
Non-business e-commerce adoption refers to the use of e-commerce by not-for profit organizations such as religious organizations,
government agencies and academic institutions to reduce their expenses or to improve their operations and customer service.
Being a new research niche in the field of e-commerce, non-business e-commerce has received very little or no research attention.
This has resulted in a very poor understanding of this niche, especially with regards to its adoption facilitators and inhibitors.
Based on this impetus, a field survey of Malaysian Universities was conducted to determine the key factors that facilitate
non-business EC adoption as well as the role of gender differential. A comprehensive list of potential facilitators for the
strategic use of information technology was derived from extant research reports and used to collect data from five public
universities in Malaysia. The data were factor-analysed to determine the key underlying dimensions of facilitators. On the
basis of the resulting five dimensions namely, relative advantage orientation, network orientation, information efficiency
orientation, innovativeness orientation and competitiveness orientation, regression analysis was done to determine the impact
of the five dimensions on adoption. Dummy variable was created for gender and applied in the regression analysis in order
to estimate the moderation effect of sex typing on the relationship between the resulting dimensions and adoption. Implications
of the findings are discussed. 相似文献
1000.