Pile Response Adjacent to Braced Excavation

The excavation of soil for the construction of basements or cut-and-cover tunnels results in ground movements. One particular concern is that the excavation-induced lateral soil movements may adversely affect any nearby pile foundation. The lateral loads imposed by the soil movements induce bending moments and deflections in the pile, which may lead to structural distress and failure. This paper presents the results of an actual full-scale instrumented study that was carried to examine the behavior of an existing pile due to nearby excavation activities resulting from the construction of a 16 m deep cut-and-cover tunnel. The pile was located 3 m behind a 0.8 m thick diaphragm wall. Excavation to the formation level that was 16 m below the ground surface resulted in a maximum lateral pile movement of 28 mm. A simplified numerical procedure based on the finite-element method was used to analyze the pile response. Generally, the theoretical predictions were in reasonable agreement with the measured results.     

一种“绝对型”电容薄膜真空计的研制

介绍用磁控溅射制作的从大气往真空约覆盖5个量程的“绝对型”电容薄膜真空规，以及与该真空规配套的真空计的电路。该真空计测量范围为1．3～105Pd，真空规与电容信号检测电路置于同一金属壳内，以避免外界干扰。规的恒温胜温度波动小于±0．1℃，有效地降低了温度的影响。电路的非线性小于0．4％，高真空下北输出漂移小于0．1％，在13～105Pa各量程内，最大校准误差小于读数的4％。     

A study on the improvement of release application characteristics of pneumatic brakes for freight train

We have performed experimental studies for the improvements of pneumatic brake systems of freight trains. Currently, most of the freight trains operated by the Korean National Railroad have either empty-load or diaphragm type brake systems. In this study, appropriate methods that the air pressure characteristics in both type of brake systems are in accordance with each other have been investigated. We have also performed running tests using a 30 car-train set to design optimum capacity of a quick release valve. The test results show that the quick release valve is considerably effective in shortening the release time of the diaphragm type brake system. In the case of a normal brake application, the diaphragm type brake system with the quick release valve reduces the release time to 34% of that of the system without the quick release valve. This release time is almost equivalent to that of the empty-load type brake system. Accordance of braking performance in different types of brake systems in a train set is expected to prevent wheel flats and to reduce maintenance costs.     

提高微压传感器灵敏度的深盆腔压力膜片研究(一)

表面微机械微小量程压力传感器采用多晶硅薄膜等有内应力的敏感膜片时，应力往往会使膜片的力学灵敏度大大下降，无法满足微量程测量的要求。波纹膜片可以消除或减小应力来提高灵敏度，但是其波纹结构本身又会造成力学灵敏度下降，从而部分抵消了应力消除的效果。提出一种新型深盆腔膜片结构，在消除应力的同时实现了比平膜片还高的力学灵敏度，可以提高微压传感器和微麦克风的灵敏度。采用解析和有限元 两种方法相结合的方法，对该种膜片进行了分析和研究。对比平膜和波纹膜结构，显示了深盆腔膜在力学灵敏度方面的显著提高。     

Innovative phase shifter for pulse tube operating below 10 K

Stirling type pulse tubes are classically based on the use of an inertance phase shifter to optimize their cooling power. The limitations of the phase shifting capabilities of these inertances have been pointed out in various studies. These limitations are particularly critical for low temperature operation, typically below about 50 K. An innovative phase shifter using an inertance tube filled with liquid, or fluid with high density or low viscosity, and separated by a sealed metallic diaphragm has been conceived and tested. This device has been characterized and validated on a dedicated test bench. Operation on a 50–80 K pulse tube cooler and on a low temperature (below 8 K) pulse tube cooler have been demonstrated and have validated the device in operation. These developments open the door for efficient and compact low temperature Stirling type pulse tube coolers. The possibility of long life operation has been experimentally verified and a design for space applications is proposed.     

沙曲选煤厂技术改造方案探讨

针对沙曲选煤厂、旧系统存在问题,对选煤工艺改造方案进行探讨,即采用预脱泥有压两产品重介旋流器主再洗、毛煤动筛排矸、浮选精煤加压过滤机回收、尾煤压滤回收工艺.通过试运行,设备状况良好,基本达到设计生产能力.     

水厂铁矿尾矿隔膜泵输送工艺研究与应用

水厂铁矿原尾矿输送工艺系统落后、管理复杂、能耗高、运行成本高，为降低矿山生产成本，对尾矿输送工艺采用隔膜泵进行改造。针对隔膜泵对入料介质的要求，通过对国内众多矿山隔膜泵给料工艺进行考察分析，结合水厂铁矿现场设备和生产实际，提出了尾矿经圆筒筛隔渣生产建筑用砂，隔渣后的尾矿经过深锥浓密机浓缩后给料到隔膜泵进行输送的新工艺。新工艺实施后，隔膜泵入料尾矿浆中+0.833 mm颗粒粒级含量仅为0.61%，基本将 1 mm以上粗颗粒剔除，能够生产出产率8.28%、模数2.5、含泥量2.5%以下的合格建筑用砂。利用改造后的深锥浓密机实现了隔膜泵稳定、均匀给料。新工艺实现了尾矿资源的高效利用，开拓了矿山企业新的经济增长点，同时满足了隔膜泵安全稳定运行的需要。     

A new cavity profile for a diaphragm compressor used in hydrogen fueling stations

The short operating life of metallic diaphragm caused by fracture is one of the main disadvantages for diaphragm compressors used in hydrogen fueling stations. A new generatrix for cavity profile is proposed through optimization using the complex method to decrease the maximal radial stresses on both oil and gas sides of the diaphragm clinging to the cavity surface. In the optimization, the convex part of the cavity generatrix is subjected to a constraint that the generatrix has a lower slope than the deformed diaphragm under a uniform pressure load. This constraint aims to avoid cavity dead volume at the end of the gas discharge process. Thus, an analytical solution for the deflection of an edge-clamped metallic diaphragm under a uniform pressure load is firstly developed. The solution employs the principle of minimum energy and the Rayleigh-Ritz method, which based on the theory of thin plates with large deflections. Experimental measurements, as well as the finite elements method (FEM), are employed to validate the solution. The analytical results are found to be in good agreement with the results of measurements and FEM simulations. Secondly, the stress of the diaphragm with a specific deflection is calculated, and the radial stress concerning both gas side and oil side of the diaphragm is taken as the objective function. Finally, a new generatrix is obtained through the optimization. The radial stress of the diaphragm clinging to the new cavity profile is validated via the FEM simulation, and results match well with each other. It also approves that the cavity dead volume is eliminated by the new generatrix at the end of the gas discharge process. Moreover, the maximal and the centric radial stress of the working diaphragm were compared between the new generatrix and the traditional generatrix under the same design parameters, the maximal and the centric radial stress of the diaphragm decreased by 8.2% and 13.9%, respectively. Based on the proposed design method, effects of the cavity volume, cavity radius, diaphragm thickness and diaphragm material properties on the maximal radial stress of the working diaphragm are further discussed.     

某航测相机的控制系统设计

就某航测相机控制分系统中的主要部分设计进行了比较详细的阐述。该相机控制系统主要包括测光机构控制、凸轮驱动控制、多快门同步控制、CCD相机同步控制、调光控制等部分。各部分依据控制流程,统一协调工作实现拍摄任务。     

喷墨打码机墨路循环系统的压力脉动抑制方法

针对以波纹管蓄能器和隔膜泵为基本元件的喷码机墨路循环系统中存在的压力脉动现象,通过对关键部件隔膜泵(含隔膜、吸入液阀、排出液阀等)与波纹管蓄能器的分析建立墨路循环系统的液压仿真模型,分析了波纹管刚度、阻尼孔孔径等重要参数对脉动吸收效果的影响,获得吸收压力脉动的波纹管的最优参数,通过试验验证了仿真结果,压力脉动抑制的关键在于波纹管的刚度必须与隔膜泵工作压力合理匹配。