GPRS手机入网测试自动化

全球移动通信系统(GSM)广泛的应用于现代通信系统就在于其良好的兼容性,不同的移动设备之间在遵守一定协议规范的条件下可以相互通信;本设计测试的是GSM第11系列GSM11.10,他包括诸多测试项,只对接收机参考灵敏度电平在GSM900与DCS1800两个频段进行测量。给出了传统形式下的手动测试和自动测试平台的比较,并建立了收信机参考灵敏度指标的自动测试平台。     

Effect of corrugated plates in an in-phase arrangement on the heat transfer and flow developments

In the present study, the numerical results of the heat transfer and flow developments in the corrugated channel under constant heat flux conditions are presented. The test section is the channel with two opposite corrugated plates which all configuration peaks lie in an in-phase arrangement. The corrugated plates with three different corrugated tile angles of 20°, 40°, and 60° are tested with the height of the channel of 12.5 mm. The model was simulated for the Reynolds number and heat flux in the ranges of 400–1600 and 0.5–1.2 kW/m², respectively. The flow and heat transfer developments are simulated by using the k-ε standard turbulent model. A finite volume method with the structured uniform grid system is employed for solving the model. The predicted results are validated by comparing with the measured data. There is reasonable agreement from the comparison between the numerical data and experimental data. Effects of relevant parameters on the heat transfer and flow developments are discussed. Due to the breaking and destabilizing in the thermal boundary zone, the corrugated surface has significant effect on the enhancement of heat transfer and pressure drop.     

Applications of electronically facilitated bidding model to preventing construction disputes

When a lump-sum public construction project is implemented, disputes often arise concerning issues around the accuracy of contracted quantities, the acceptability of unit prices of cost items, and whether an “equal (or equivalent)” for a product (equipment or material) can be used. In Taiwan, contracted quantities and unit prices are primarily based on owner's estimations, and the trademarks of a product specified in a tendering documentation are only for reference. A contractor has to struggle for profit when the amount of work completed differs from the contracted amount, when change orders are priced according to the owner's estimates, and when inexpensive equals may be used. This work comprehensively elaborates the background of the current practice, and presents experience of applying an electronically facilitated bidding model to evaluating the bidder's submitted quantities, unit prices and equals in several practical projects in Taiwan. Results of this study indicate that the aforementioned construction disputes can be prevented or at least mitigated.     

DF_4内燃机车柴油机润滑油的热重分析

通过对DF_4内燃机车柴油机润滑油的热重曲线TG和微商热重曲线DTG的分析,探讨了这种润滑油的衰变规律。     

Experiments and simulations of the mechanical performance of repaired panels

Firstly, the compress experiment is undertaken to investigate the efficiency of repaired panels in this paper, and then modeling of the mechanical behavior of the repaired composite panel under compressive static load is conducted by using of the finite element method. The effect of geometric non-linearity on the stress–strain response is considered in the numeric analysis. Fatherly, the user material subroutine (UMAT) is integrated with the ABAQUS package with the geometric non-linearity effect for studying the damage initiation and its progression in the composite structure, and quadrilateral, linear, thick shell elements (S8R) are adopted. Finally, the predicted strain distribution, damage evolution and strength of the laminate are compared with the test results.     

A globally convergent algorithm for transportation continuous network design problem

The continuous network design problem (CNDP) is characterized by a bilevel programming model, in which the upper level problem is generally to minimize the total system cost under limited expenditure, while at the lower level the network users make choices with regard to route conditions following the user equilibrium principle. In this paper, the bilevel programming model for CNDP is transformed into a single level convex programming problem by virtue of an optimal-value function tool and the relationship between System Optimum (SO) and User Equilibrium (UE). By exploring the inherent nature of the CNDP, the optimal-value function for the lower level user equilibrium problem is proved to be continuously differentiable and its derivative in link capacity enhancement can be obtained efficiently by implementing user equilibrium assignment subroutine. However, the reaction (or response) function between the upper and lower level problem is implicit and its gradient is difficult to obtain. Although, here we approximately express the gradient with the difference concept at each iteration, based on the method of successive averages (MSA), we propose a globally convergent algorithm to solve the single level convex programming problem. Comparing with widely used heuristic algorithms, such as sensitivity analysis based (SAB) method, the proposed algorithm needs not strong hypothesis conditions and complex computation for the inverse matrix. Finally, a numerical example is presented to compare the proposed method with some existing algorithms.     

Effect of Magnetic Interaction on Thermally Activated Reversal in a Magnet With a Distribution of Energy Barriers

The time dependence of magnetization is usually expressed as M(t)=M₀-SInt [see Proc. Phys. Soc. 62, 562 (1949)] for magnetic viscosity experiments. Considering magnetic interaction during the thermal activation process, a form as M(t)=M₀-SIn(t+t₀) is deduced. The dipolar interaction and exchange coupling in a magnet can lead to positive and nonpositive t₀, respectively. In the experiments of the magnetic viscosity for nanocrystalline Pr₂Fe₁₄B ribbons, the existence of positive t₀ is confirmed.