Design of spherical and planar crank-rockers and double-rockers as function generators—I

The design of crank-rockers may be considered as a special case of synthesizing a function generator to match two prescribed velocity ratios, in which these velocity ratios are zero. The conception is based on the equations of relative poles. Like in the well-known planar case, where the loci of A₁ (crack-pin centre) and B₁ (rocker-pin centre) are both circles and straight lines, these loci in the spherical case are ellipses and great circles. Synthesis equations in simple trigonometric forms are presented for the spherical case, which are analogous to those in the planar case. Ranges of rotation angle φ₃ of the crank and those of the parameter φ₀, the initial position angel of the crank, are discussed. Simplified procedure for optimizing the transmission angles in both spherical and planar cases are described. Examples are given.     

Design of spherical and planar crank-rockers and double-rockers as function generators—II double-rockers

The design of double-rockers may also be considered as special cases of synthesizing a function generator to match two prescribed velocity ratios. The synthesis equations thus obtained are simple and concise. In a certain aspect, the syntheses of double-rockers and crank-rocers are fundamentally the same, and the loci of A₁ and B₁ are ellipses and great circles for spherical double-rockers, and circles and straight lines for planar double-rockers. Optimization procedure of transmission angle so that it deviates equally from both sides of 90° has been discussed.     

Design and Optimization of Wheel-legged Robot：Rolling-Wolf

Though the studies of wheel-legged robots have achieved great success, the existing ones still have defects in load distribution, structure stability and carrying capacity. For overcoming these shortcomings, a new kind of wheel-legged robot（Rolling-Wolf） is designed. It is actuated by means of ball screws and sliders, and each leg forms two stable triangle structures at any moment, which is simple but has high structure stability. The positional posture model and statics model are built and used to analyze the kinematic and mechanical properties of Rolling-Wolf. Based on these two models, important indexes for evaluating its motion performance are analyzed. According to the models and indexes, all of the structure parameters which influence the motion performance of Rolling-Wolf are optimized by the method of Archive-based Micro Genetic Algorithm（AMGA） by using Isight and Matlab software. Compared to the initial values, the maximum rotation angle of the thigh is improved by 4.17%, the maximum lifting height of the wheel is improved by 65.53%, and the maximum driving forces of the thigh and calf are decreased by 25.5% and 12.58%, respectively. The conspicuous optimization results indicate that Rolling-Wolf is much more excellent. The novel wheel-leg structure of Rolling-Wolf is efficient in promoting the load distribution, structure stability and carrying capacity of wheel-legged robot and the proposed optimization method provides a new approach for structure optimization.     

Design and implementation of 30„ geometry PIG

This paper introduces the developed geometry PIG (Pipeline Inspection Gauge), one of several ILI (In-Line Inspection) tools, which provide a full picture of the pipeline from only single pass, and has compact size of the electronic device with not only low power consumption but also rapid response of sensors such as calipers, IMU and odometer. This tool is equipped with the several sensor systems. Caliper sensors measure the pipeline internal diameter, ovality and dent size and shape with high accuracy. The IMU (Inertial Measurement Unit) measures the precise trajectory of the PIG during its traverse of the pipeline. The IMU also provide three-dimensional coordination in space from measurement of inertial acceleration and angular rate. Three odometers mounted on the PIG body provide the distance moved along the line and instantaneous velocity during the PIG run. The datum measured by the sensor systems are stored in on-board solid state memory and magnetic tape devices. There is an electromagnetic transmitter at the back end of the tool, the transmitter enables the inspection operators to keep tracking the tool while it travels through the pipeline. An experiment was fulfilled in pull-rig facility and was adopted from Incheon LT (LNG Terminal) to Namdong GS (Governor Station) line, 13 km length.     

Rotordynamics and Design Methods of an Oil-Free Turbocharger©

The feasibility of supporting a turbocharger rotor on air foil bearings is investigated based upon predicted rotordynamic stability load accommodations, and stress considerations. It is demonstrated that foil bearings offer a plausible replacement for oil-lubricated bearings in diesel truck turbochargers. Also, two different rotor configurations are analyzed and the design is chosen which best optimizes the desired performance characteristics. The method of designing machinery for foil bearing use and the assumptions made are discussed.     

Development of a Centrifugal Oil Lubricator for Long-Term Lubrication of Spacecraft Attitude Control Systems—Design and Theory

Spacecraft, irrespective of their mission's purpose, contain a number of moving mechanical assemblies such as momentum/reaction wheels, control moment gyros, solar array drives, etc. Most problems encountered with these moving systems are related to tribology and, specifically, lubrication. Lubrication problems result from the loss of lubricant from the working zone by evaporation, surface migration, etc. Therefore, to ensure long-term uninterrupted performance of these systems, an efficient lubricant replenishment system is essential. This article describes the development of a novel lubricant supply system that can supply lubricant for more than 30 years at a controlled rate of few micrograms/hour. A mathematical model of a such lubrication system is developed to predict its useful life and performance. In addition, a computational fluid dynamics (CFD) simulation study of the lubricator is carried out and the results are used to verify and refine the theoretical model. Finally, the refined model is used to predict the performance of the lubricator for a period of 30 years.     

Analysis of Ergonomics and Design about College Students’ Housing

论文针对大学生宿舍建设问题,对18m2四人间学生公寓进行改进设计及人机工程学分析,尝试提出一套适合当前我国国情和未来一段时间内社会发展需要的大学生宿舍设计的方法.提出改进学生宿舍设计和改善宿舍居住环境质量的建议.     

Design and dynamic analysis of single-axis integrated inertia measurement device

The structure and measurement theory of a single-axis integrated inertia measurement device are discussed in this paper.The acceleration and angle velocity can be detected by the proposed sensor at the same time.The kinetic model of the device is also established.In addition,the signal generation of the single-axis integrated inertiameasurement device is analyzed and simulated.The results of the model are consistent with simulation result.     

Design and Simulation of PVDF‐MOSFET Based MEMS Hydrophone

Abstract

Modeling has become a vital tool of investigation in all fields, since experimenting with real systems is not only costly, but also time‐consuming and even impossible in some situations. This work presents the design and simulation of an integrated PVDF‐based MEMS hydrophone with improved sensitivity, which contains a MOSFET sense amplifier. The piezoelectric polymer, polyvinylidene fluoride (PVDF), senses the input acoustic signal. As hydrophone size decreases, it becomes necessary to provide an amplifier or buffer in close proximity to avoid sensitivity loss due to interconnect capacitance. This suggests the concept of hydrophones merged with electronics in an integrated circuit environment. So, the integration of PVDF with an on‐chip MOSFET is implemented. The extended gate electrode of the MOSFET is placed over an epitaxial layer isolated from the silicon substrate and is padded with a dielectric layer, SU‐8, which significantly reduces the extended gate capacitance and, therefore, increases the sensor sensitivity. The variation of the transducer output when the input acoustic signal is applied is studied. The simulation is done using the MEMS simulation software, Coventorware.     

Overview of Rubik’s Cube and Reflections on Its Application in Mechanism

Rubik’s Cube is a widely popular mechanical puzzle that has attracted attention around the world because of its unique characteristics. As a classic brain-training toy well known to the public, Rubik’s Cube was used for scientific research and technology development by many scholars. This paper provides a basic understanding of the Rubik’s Cube and shows its mechanical art from the aspects of origin and development, characteristics, research status and especially its mechanical engineering design, as well as making a vision for the application in mechanism. First, the invention and origin of Rubik’s Cube are presented, and then the special characteristics of the cube itself are analyzed. After that, the present researches of Rubik’s Cube are reviewed in various disciplines at home and abroad, including the researches of Rubik’s Cube scientific metaphors, reduction algorithms, characteristic applications, and mechanism issues. Finally, the applications and prospects of Rubik’s Cube in the field of mechanism are discussed.     

Design and application of a borehole–surface microseismic monitoring system

Borehole–surface microseismic monitoring is a new approach for monitoring artificially induced hydraulic fracturing in an oil or gas field. However, ineffective communication links and incompatible data formats between current borehole- and surface-based monitoring systems mean that borehole–surface monitoring cannot be reported in real time. To solve this problem, the borehole–surface microseismic monitoring system reported here allows fracturing points through inversion and the development of fractures to be viewed in real time. Private cloud technology is used to control the instruments, manage the borehole and the surface database, and process the data. This system ensures high performance and availability of the system. The data acquisition modules and the geophones used in the borehole and surface instruments were calibrated in the laboratory to ensure the consistency of the acquired microseismic signals. The monitoring system located 82 microseismic events with a fracture azimuth of N84°E during fracture production in the Daqing Oilfield. Subsequent analysis showed that the locations of the fractures and their strike directions were consistent with the theory of hydraulic fracture propagation and the local crustal stress field. The results demonstrate that the monitoring system effectively and promptly processed data, thus enabling real-time borehole–surface microseismic monitoring.     

Test Results of Key and Spherical Pivot Five-Shoe Tilt Pad Journal Bearings—Part II: Dynamic Measurements

Tests were conducted to measure the dynamic characteristics for two types of five-shoe tilt pad journal bearings having a load between pads configuration. Dynamic measurements of the two bearings are presented for 5000, 7000 and 12,000 rpm, and unit loads ranging from 126 kPa to 1724 kPa. Comparisons are made between the measured data and the theoretical prediction. Test data includes fluid film stiffness and damping, with calculated uncertainties and the measured radial stiffness of the pivots. The measured dynamic characteristics show the bearings differ with respect to stiffness and damping, while the measured radial pivot stiffnesses were nearly identical     

Rapid Design and Performance Evaluation of Steady-State Journal Bearings—A Technique Amenable to Programmable Hand Calculators

A simple technique for the rapid design and performance evaluation of steady-state journal bearings is presented. The technique which is amenable to hand calculator use is compared with a numerical solution for all relevant design parameters. Results indicate that the bearing designer may utilize the technique over a wide range of (L/D) and eccentricity ratios without serious error.     

Design and application of refrigerant recovery and filling control system based on MSP430

提出了一种应用于空调系统的多功能冷媒回收加注装置的控制方案。本方案硬件电路基于MSP430单片机设计,同时采用了高精度称重传感器和高性能放大器;软件设计采用中位值平均滤波算法。本装置不仅可以将冷媒废液净化后回收,而且可以定量加注新冷媒。同时,本装置具有施压、抽真空、加冷冻油等功能。实践证明,本控制系统成本较低、稳定性好,具有较高的实用价值。     

Prospect Analysis for Tire Industry Development and Each Kind of Raw Material Demand in Our Country

In recent years, tire industry develops very fast in our country. It mainly depends on the three aspects drawing of domestic demand, exportation and investment. Along with the road, automobile and transportation enterprises unceasingly developing in our country as well as the people＇s living standard unceasingly enhancing, the automobile tire, especially the radial tires are developed very fast, the year rate of all steel radial truck tire is increased all above 50% and the year rate of semi steel radial tires is increased above 20%.     

Design and experiment of ϕ-type-knots knotters on Chinese small square balers

Since the knotters on the Chinese rectangular balers are imported from outside of the country, Chinese knotters with independent intellectual property rights is far away from being closed. In order to harvest a large quantity of straw in a short period on the small-scale lands of China, basic requirements on the knotters are summarized. Mathematical model of the knotter is also determined uniquely. Furthermore, the ~-type-knots knotter equipped on the Chinese square baler to form the ~ type knots is designed. Knotting rate experiments of the qb-type-knots knotter on the test bench and in the wheat/maize straws covered fields are carried out to check the knotting performances of the knotter. The parameters of the formed knots are also tested. The experiments results show that the knotting rate of the qb-type-knots knotter reaches 100.0% on the test bench without straws, while reaches 99.6% in the wheat straws covered field and 100.0% in the maize straws covered field. The average maximum force in the knotting process is 194.7 N in the lab experiment. The length out of the knots formed in lab is 15.9%-20.6% lower than the knots formed in the field experiment. The breaking force of the knots formed in the field is 115.9%-167.2% higher than the knots formed in lab due to the higher preload and interactions with the compacted bales. Highly relevant relationships exist between the breaking force of the formed knots and the maximum force in the forming process of the knots in the lab experiment. The designed knotter breaks out the embarrassing situation of the domestic knotters which don＇t have independent intellectual property rights, and promotes the development of Chinese knotter technology, and the mathematical model is helpful for designing new type of knotters.     

Design and finite element analysis of Φ510 mm SiC ultra-lightweight mirror

针对Φ510 mmSiC超轻量化反射镜的研制,提出了一剖面为船型、内部为正三角形、面板加密呈正六边形的轻量化结构.当设计重量为1.85 kg时,通过调整各个结构参数与另外两种相同重量的轻量化结构进行了比较.结果表明,在同样背部6点支撑作用下,该超轻量化结构在光轴指向天顶时由自重引起的面形(RMS)具有较大优势.利用PatranNastran有限元软件模拟计算了该超轻量化反射镜在光轴水平状态下的自重镜面变形,并对其进行了热力学及动力学特性分析.分析结果显示,该超轻量化反射镜各项指标均能满足使用要求.最终,根据设计结果试制加工了一块镜坯,初步加工后的重量约为2.2 kg,面密度约为10.8 kg/m2,已达到目前SiC超轻量化反射镜的先进水平.     

Coke Formation from Aircraft Turbine Engine Oils: Part I — Deposit Analysis and Development of Laboratory Oil Coking Test

The authors report here the results of a study undertaken to determine how aircraft engine oil degrades to form coke in static films on engine components and the impacts of additives and surface materials upon the coke production processes. The research is presented in two parts. This first paper deals with the initial research to develop a simple laboratory oil-coking test capable of monitoring antioxidant depletion, oil degradation, and coke formation of stressed aircraft turbine engine oils. Details of the analytical chemistry experiments performed on the stressed samples to quantitate the percentage of oil, polymer dissolved in the oil, and insoluble coke are also presented. The second paper (Part 2) (I) deals with more quantitative measurements of the degradation of thin layers of oil on heated surfaces. Effects of different oils and surfaces are explored.

The results presented in Part I show that simple open-vial laboratory tests involving thin films of oil produce polymer and coke similar to the deposits seen on failed face seals taken from operating aircraft engines and isolated from used engine oils. Coking reactions require oxygen to deplete the antioxidant package and to polymerize/decompose the ester basestock of the oil. After the antioxidant package is depleted, the ester basestock polymerizes to form small oil-soluble polymers. As the oil spends additional time at elevated temperature, these polymers increase in molecular weight and change in chemical composition becoming insoluble in the oil, producing deposits. Although the antioxidants inhibit the polymer/coke reactions, the antioxidants are incorporated in the formed deposits increasing the deposit amount. Consequently, these results indicate the proper concentration and choice of antioxidants will allow elimination, not just reduction, of deposits on engine components coated with thin layers of static oil films.     

Design and Performance Analysis of Symmetrical-"几"-shapedInverted-Tension Lamina Emergent Joint

设计了 一种新型抗拉压平面折展铰链T-LEJ(Tension Lamina Emergent Joint),命名为对称倒"几"字形抗拉压平面折展铰链(Symmetrical Inverted"几"shaped Tension Lamina Emergent Joint),简称对称倒"几"字形T-LEJ铰链.设计了铰链的结构,采用弹簧等效法,推导了铰链的弯曲等效刚度与拉压等效刚度计算式.设计了铰链实例进行理论计算同时进行有限元仿真,二者之间的误差在3％-6％之间,验证了所得等效刚度计算式的正确性.对具有相同结构特征尺寸的对称倒"几"字形T-LEJ铰链与Howell提出的I-LEJ铰链、IT-LEJ铰链进行性能对比分析,结果表明对称倒"几"字形T-LEJ铰链的抗拉压能力是I-LEJ铰链的6.25倍,略低于IT-LEJ铰链.针对对称倒"几"字形T-LEJ铰链与IT-LEJ铰链进行失效对比分析,其弯曲变形能力是IT-LEJ铰链的2.09倍.表明对称倒"几"字形T-LEJ铰链具有更好的综合性能,验证了铰链结构设计的合理性与有效性.