Hydraulic lift systems with piston type pump

More difficult conditions of oil production process in recent years impose the necessity of finding out new technical solutions that will provide reliable and efficient lifting of reservoir fluid to the surface.Technical solution presented in this paper, hydraulically driven piston pump, is one of the attempts in the field of artificial exploitation methods, to find a solution that will work effectively in different well types (vertical, horizontal and directional) and at depths that are greater than those achieved until today.The task of this paper is to show the innovation in the pump construction. Innovations are made in the coiled tubing construction, one pipeline instead two or three; double acting type pump with reservoir fluid repression, towards the surface, through a channel drilled in the piston.The new technical solution, laboratory prototype, has been tested and the results are presented in tables and on graphs in this paper. The aim is that after testing the laboratory prototype comes to the data that will be used for the design of industrial product.     

天津市第一中心医院空中连廊设计与施工

以某工程实例详细介绍了结构钢连廊设计过程,通过比较多个施工方案,确定出合理可行的施工方法,提出施工过程中的注意事项,可为类似工程提供工程实践经验。     

水轮发电机推力轴承高压油顶起装置的设置和应用

为了延长水轮发电机机组的使用寿命,在推力轴承上设置了高压油顶起装置。本文叙述了高压油顶起装置的结构、安装、调整及使用维修,并进行了润滑计算。     

导轨式整体爬升脚手架强度验算

以导轨式整体爬升脚手架为研究对象，取标准层层高≤3.6m,Lmax≤6.8m的单元架体，并且针对工程的具体要求取最大值做为计算参数，施工前对架体的局部重要受力杆件如穿墙螺栓、斜拉杆、连接板进行了强度验算，同时也对受力点结构砼的抗压强度进行了验算。验算结果满足强度要求，从而在理论上为导轨式整体爬升脚手架施工应用提供了安全保证。     

新型平板钢闸门的设计与理论研究

介绍的是工程上实用性较强的一种新型闸门，它主要解决了水泵站集水井内进水间与吸水间之间的闸门静水起吊问题。这种新型闸门结构简单，安装维修便利，并且节约了大量的能耗，属经济实用型设备。本文同时还应用了水力学方法对该闸门的节能特点进行了理论分析和论证，并阐述了这种新型闸门的适用范围和推广意义。     

连续气举采油最大产量的优化计算法

根据节点系统分析原理和最优多相流相关式,讨论了利用计算机对连续气举采油时的最大产量进行优化运算的方法,得到了满意的结果。     

Wind tunnel modelling as a means of predicting the response of chimmeys to vortex shedding

The limitations of wind tunnel testins, particularly for chimneys with a circular cross-section are discussed. The use of data from full-scale observations and wind tunnel tests at high Reynolds numbers in conjunction with suitable mathematical models are suggested to obtain wind load and wind response estimates that offer a higher level of reliability than wind tunnel estimates.     

Maximum acceptable weights for asymmetric lifting of Chinese females

This study used the psychophysical approach to evaluate the effects of asymmetric lifting on the maximum acceptable weight of lift (MAWL) and the resulting heart rate, oxygen uptake and rating of perceived exertion (RPE). A randomized complete block factorial design was employed. Twelve female college students lifted weights at three different lifting frequencies (one-time maximum, 1 and 4 lifts/min) in the sagittal plane and at three different asymmetric angles (30 degrees, 60 degrees, and 90 degrees ) from the floor to a 68-cm height pallet. This lifting experiment was conducted for a 1-h work period using a free-style lifting technique. The MAWLs for asymmetric lifting were significantly lower than those for symmetric lifting in the sagittal plane. The MAWL decreased with the increase in the angle of asymmetry. However, the heart rate, oxygen uptake and RPE remained unchanged. Though the MAWL decreased significantly with lifting frequency, both the physiological costs (heart rate and oxygen uptake) and rating of perceived exertion increased with the increase in lift frequency. The most stressed body part was the arm. Lifting frequency had no significant effect on the percentage decrease in MAWL from the sagittal plane values. On average, decreases of 5%, 9% and 14% for MAWL at 30 degrees, 60 degrees and 90 degrees asymmetric lifting, respectively, were revealed. This result was in agreement with the findings of Chinese males studied by Wu [Int. J. Ind. Ergonom. 25 (2000) 675]. The percentage decrease in MAWL with twisting angle for the Chinese participants was somewhat lower than those for Occidental participants. In addition, even though there was an increase in heart rate and RPE with the increase in the symmetrical lift angle for Occidental participants, it was different from the Chinese participants. Lastly, the 1991 NIOSH equation asymmetry multiplier is more conservative in comparison with the results of the present study.     

Madsen求阶算法的改进和推广

文章分析了仅适用于特征为2和3的域上的一种椭圆曲线求阶算法—Madsen求阶算法,并对此算法进行了改进和推广,提高了Madsen算法的运算速度。     

Single Switch DC-DC Boost Converter using Diode-Capacitor Module and Capacitor-Inductor-Capacitor Lift

ABSTRACT–

This article presents a single switch DC-DC boost converter using diode-capacitor (DC) modules and capacitor-inductor-capacitor (CLC) lifts. This topology can step-up the voltage of battery-input sources and power the DC-voltage bus of practical applications. The output voltage is the superposition of the voltage of capacitors in each module and inductors in each lift. Operational modes in on-off state can largely increase the step-up ratio of the proposed converter. The voltage gain of the circuit has a wide range with only one switch to control the operation of it. In addition, the extended circuit with multi-module and multi-lift is also derived and analyzed in this article to expand the potential application of the proposed topology. The steady-state characteristics of the proposed circuit are presented in detail in this article. Hardware-based circuit employing one module and one lift will be tested using a battery and experimental results can verify the potential value of this design.