Exact algorithms for the job sequencing and tool switching problem

The job Sequencing and tool Switching Problem (SSP) involves optimally sequencing jobs and assigning tools to a capacitated magazine in order to minimize the number of tool switches. This article analyzes two integer linear programming formulations for the SSP. A branch-and-cut algorithm and a branch-and-bound algorithm are proposed and compared. Computational results indicate that instances involving up to 25 jobs can be solved optimally using the branch-and-bound approach.     

Fracture mechanisms and failure processes at stiffener run-outs in polymer matrix composite stiffened elements

This paper describes the fractographic analyses of three stringer run-out designs which had been loaded to failure in tension. The main aims of the investigation were to deduce the failure processes in the elements, and to characterise the effect of local geometry of the stringer run-out on the failure process. The analysis showed that the critical failure mechanism in the elements was the development of +45° ply splitting at the skin surface, initially under mode I dominated intralaminar fracture. However, as these splits grew beneath the stringer foot, the mode II component increased. This led to mixed-mode delamination growth, extending parallel to the +45° ply, at the skin/adhesive interface. Subsequently, the delamination migrated through the skin via ply splits, ultimately reaching the interface between the second and third (−45°/0°) plies, in which it remained until catastrophic failure.

Extending and tapering the stringer foot led to shifting of the site of the +45° ply splitting; this was attributed to in-plane tensile stresses in the skin being inhibited in the modified designs. The reduced out-of-plane support on the stiffener foot in the modified designs led to an increase in the mode I component at the delamination from the stringer tip. It also led to an increase in the degree of multi-plane delamination growth. Based on the fractographic observations, recommendations for modelling the elements were suggested.     

Normalizing Behavior of Unsaturated Granular Pavement Materials

One of the important components of a flexible pavement structure is granular material layers. Unsaturated granular pavement materials (UGPMs) in these layers influence stresses and strains throughout the pavement structure, and have a large effect on asphalt concrete fatigue and pavement rutting (two of the primary failure mechanisms for flexible pavements). The behavior of UGPMs is dependent on water content, but this effect has been traditionally difficult to quantify using either empirical or mechanistic methods. This paper presents a practical mechanistic framework for determining the behavior of UGPMs within the range of water contents, densities, and stress states likely to be encountered under field conditions. Both soil suction and generated pore pressures are determined and compared to confinement under typical field loading conditions. The framework utilizes a simple soil suction model that has three density-independent parameters, and can be determined using conventional triaxial equipment that is available in many pavement engineering laboratories.     

基于参数辨识的一种动态补偿数字滤波器

提出了一种能明显改善系统动态性能的动态补偿数字滤波器。分析了动态补偿数字滤波器的基本原理。为了使动态补偿滤波器始终工作在最佳参数状态下,且更具有通用性,结合参数辨识,利用基于Householder变换的自适应最小二乘法对传感器的动态性能进行在线补偿,其特点是数值稳定性好、估计精度高。试验表明:对动态品质较差的双孔悬臂梁式压力传感器进行在线补偿,可以使其动态性能得以较好的改善。     

Delphi在变配电监控系统中的应用

本文介绍Delphi软件开发工具的功能和特点以及用Delphi开发变配电监控软件的系统设计。     

Bond Between Near-Surface Mounted Carbon-Fiber-Reinforced Polymer Laminate Strips and Concrete

In recent years, a strengthening technique based on near-surface mounted (NSM) laminate strips of carbon-fiber-reinforced polymer (CFRP) has been used to increase the load-carrying capacity of concrete and masonry structures by introducing laminate strips into precut grooves on the concrete cover of the elements to be strengthened. The high experimentally derived levels of strength efficacy with concrete columns, beams, and masonry panels have presented NSM as a viable and promising technique. This practice requires no surface preparation work and, after cutting the groove, requires minimal installation time compared to the externally bonded reinforcing technique. A further advantage associated with NSM CFRP is its ability to significantly reduce the probability of harm resulting from fire, acts of vandalism, mechanical damage, and aging effects. To assess the bond behavior of CFRP to concrete, pullout-bending tests have been carried out. The influences of bond length and concrete strength on bond behavior are analyzed, the tests are described, and the results are presented and discussed in detail. Finally, a local stress-slip relationship is determined based on both experimental results and a numerical strategy.     

Immunohistochemistry of neuronal nitric oxide synthase and protein nitration in the striatum of the aged rat

To ascertain the possible implications of the nitric oxide (NO*) producing system in striatal senescence, and by using immunohistochemistry and image-processing approaches, we describe the presence of the enzyme nitric oxide synthase (NOS), the NADPH-diaphorase (NADPH-d) histochemical marker, and nitrotyrosine-derived complexes (N-Tyr) in the striatum of adult and aged rats. The results showed neuronal NOS immunoreactive (nNOS-IR) aspiny medium-sized neurons and nervous fibres in both age groups, with no variation in the percentage of immunoreactive area but a significant decrease in the intensity and in the number of somata with age, which were not related to the observed increase with age of the striatal bundles of the white matter. In addition, NADPH-d activity was detected in neurons with morphology similar to that of the nNOS-IR cells; a decrease in the percentage of area per field and in the number of cells, but an increase in the intensity of staining for the NADPH-d histochemical marker, were detected with age. The number of neuronal NADPH-d somata was higher than for the nNOS-IR ones in both age groups. Moreover, N-Tyr-IR complexes were observed in cells (neurons and glia) and fibres, with a significant increase in the percentage of the area of immunoreaction, related to the increase of white matter, but a decrease in intensity for the aged group. On the other hand, we did not detect the inducible isoform (iNOS) either in adult or in aged rats. Taken together, these results support the contention that NADPH-d staining is not such an unambiguous marker for nNOS, and that increased protein nitration may participate in striatal aging.     

Optical temperature sensor based on ZnO thin film's temperature-dependent optical properties

A reflective fiber temperature sensor system based on the ZnO thin film is proposed. The transmittance spectra and temperature dependent optical property of the sensing head with ZnO thin film is investigated theoretically and experimentally, and the temperature resolution of ～1?°C is obtained in the temperature region of 300-773 K. The temperature sensing system is only related to the wavelength shift of transmittance spectra, and has a high stability without depending on the incident light intensity. This research results also indicate a fiber optical sensor with a broad temperature measurement range (10-1800 K) can be gained as a promising temperature sensing device, and can be applied into some extremely environments, such as aircraft, nuclear power station and power transmission system, and so on.     

屏蔽泵石墨轴承材料的强度和耐磨性研究

对屏蔽泵的石墨轴承材料的强度、磨损性和摩擦系数进行了实验研究。在DWD-3020电子万能试验机上对普通石墨和浸润树脂石墨材料的弹性模量进行了测定，同时确定了材料的拉伸和压缩强度极限。在Falex摩擦磨损机上对材料进行了磨损试验，得到了转速和载荷对这两种材料磨损的影响，并利用CSM950扫描电子显微镜对其摩擦表面作了形貌分析。     

信息不完备模型下的敏捷制造调度系统研究

针对敏捷制造单元调度问题的动态性、开放性和信息不完备等特点，构建了基于多代理生产组织和运行模式的生产任务调度系统框架结构，研究了敏捷制造环境下的不完备信息模型，提出基于CNCP扩充网协议的自组织招标机制以及基于遗传算法的调度优化模型。实验证明，在不完备信息模型下采用该模型可求取调度目标的最优解。