支撑函数法在平底摆动从动件等宽凸轮机构设计中的应用

通过引借积分几何中“支撑函数”和“宽度函数”等概念和通盘考虑平底摆动从动件等宽凸轮机构的诸种型式，推导得到了其凸轮轮廓的曲率半径、外凸判据、参数方程和周长的通用计算公式。     

支撑函数法在等宽凸轮机构设计中的应用

通过引入积分几何中“支撑函数”和“宽度函数”等概念 ,导出了等宽平底直动从动件盘形凸轮机构凸轮轮廓的外凸判据、参数方程、周长和面积的计算公式     

支撑函数在机构学中的若干重要应用

支撑函数在机构学中的若干重要应用马喜川，常勇，李延平（黑龙江商学院）１引言积分几何渊源于几何概率，最早的几何概率命题远在十八世纪即已出现。１９３５年至１９３９年间，德国数学家Ｗ．Ｂｌａｓｃｈｋｅ及其学派在Ｈａｍｂｕｒｇ大学的讨论班上探讨了大抵皆来自古...     

固液两相流泵叶轮的优化设计方法

论述利用两相流理论优化设计固液混输泵叶轮的方法，首先建立数学模型，其中轴面几何参数优化数学模型中，进口建立单目标函数，出口建立多目标函数，并采用线性加权法构成一个新目标函数。权重系数可视需要灵活选取。平面几何参数优化数学模型，是在轴面几何参数优化的基础上，以流道内水力损失最小为原则建立目标函数，优化出叶型包角的最优值。优化计算使叶轮几何参数之间优化匹配得当，整泵的效率提高，寿命延长。     

基于CAD的四杆机构函数生成机构几何图解法

将函数生成四杆机构图解法的几何关系转化为函数关系，建立函数关系式，采用了基于CAD的几何图解法对传动角的四杆机构函数生成机构进行了设计，可图示运动过程并能实时修改。     

函数凸轮数控加工刀具中心坐标及凸轮轮廓计算

一、刀具中心几何速度及几何加速度计算函数凸轮的最大优点是：在运动过程中，始终保持厂速度、加速度及曲率半径的连续性。本文采用三次样条函数来计算刀具中心的几何速度及几何加速度。对三次样条函数S（X），在区间［X。－；，X。〕上y（X）是线性函数，用mi（i—0，1，…n）来表示函数S（x）的二阶导数＊”（X）在X。处的值：S”（J）一m；（i—0，1，…n）………………（）则在区间卜i．l，x。〕上S”（x）可写成：S＼工）一i。＿l（l。一l）／人十l。（l一x。－）／hi（2）式中九一X；一X，－1对＊”（X）在区间【X；－；，X，…     

CAD/CAM关键技术--曲面造型

在飞机、轮船，汽车的外形设计中，涉及到几何造型的关键内容－曲面造型。这些复杂的形状一般不能够用解析几何中的曲折和曲面来描述，故形成了一门以函数逼近论，微分几何，计算数学以及数控技术为基础的新兴学科，计算几何， 主要对CAD／CAM关键技术－－曲面造型，进行了归类与探讨。     

基于MDT的参数化产品设计

提出了一种基于ＭＤＴ的参数化产品设计方案。该方案使产品的几何和非几何特性全部参数化，并通过定义变量间的函数并联，在外部建立数据源，然后导入到ＭＤＴ中，实现对产品所有几何和非几何变量的动态驱动，使设计工作的主要任务集中到非几何参数的求解上。叙述了实施该方法的基本过程和要点，并以压力容顺的参数化设计为例，阐述了该方案在设计实践中的应用。     

几何非线性问题的无网格法分析

用局部Petrov-Galerkin方法求解几何非线性问题，这是一种真正的无网格方法。这种方法采用移动最小二乘近似函数作为试函数；只包含巾心在所考虑点处的规则局部区域上以及局部边界上的积分；所得系统矩阵是一个带状稀疏矩阵。该方法可以容易推广到求解非线性问题以及非均匀介质力学问题。在涉及几何非线性问题的数值方法中，通常都采用增量和迭代分析的方法。本文从虚功原理出发，用移动最小二乘近似函数的权函数替代虚位移，并在整个分析过程中所有变量的表达格式都是采用全拉格朗日格式。数值算例表明，无网格局部Petrov-Galerkin方法在求解几何非线性问题时仍具有很好的精度。     

逆向分层自动添加支撑的算法与实现

分析了快速原型中支撑对成型实体及成型过程影响，在必须添加支撑时，根据支撑与成型实体的几何依赖关系，采用在逆向分层的过程中自动添加支撑的方法。该算法从选定的零件分层方向的最高顶点开始向下逆向分层或从零件层片文件的最后一层向前读入层片文件，在分层过程中或读入层片文件过程中快速而准确获得成型任意形状的层片轮廓零件所必需的支撑；提出采用轮廓偏置的方法确定是否添加支撑。本算法与传统的算法相比可以最大限度地避免或减少所需的支撑添加，同时克服了传统支撑算法中的重复运算，有效地提高了快速成型中前置数据处理的效率。     

Simultaneous velocity profile and temperature profile measurements in microfluidics

Simultaneous non-intrusive temperature and velocity measurements in flows are of high technological interest, e. g. to study the heat transfer in microfluidic environments. However, a measurement system that offers a low velocity uncertainty and micrometre spatial resolution as well as highly accurate temperature measurements in a single device has not been demonstrated so far. In this work, this problem is solved by combining a Laser Doppler Velocity Profile Sensor (LDV-PS) with Laser-Induced Fluorescence (LIF). Seeding particles are employed, that contain the fluorescent dyes uranine and rhodamine B. The multiple dye approach eliminates the influence of the droplet size. Relative velocity uncertainties of down to 0.4% and a temperature uncertainty of down to 0.24 ${}^{\circ }$C with a spatial resolution of $10\mathrm{\mu }\mathrm{m}$ are achieved in a demonstration air flow experiment. The method has the potential to be optimised for different temperature ranges and uncertainty requirements, making it applicable on a wide range of thermal flows like fuel cells or microbioreactors. A better understanding of heat exchange processes can improve the energy efficiency of microfluidic devices.     

A novel method for micro-gap control in electrogenerated chemical polishing

In the electrogenerated chemical polishing (EGCP), material removal rate (MRR) is inversely proportional to the processing gap. To polish a workpiece with a large area, high and uniform MRR is necessary, which prefers a small and uniform processing gap. Based on the principle of the hydrostatic support, a novel micro-gap control method is proposed. The method uniformly controls the gap between the electrode and workpiece to a micro level over a large area. A relationship between the gap size and the inlet pressure is derived theoretically and verified experimentally. The proposed method is successfully applied to the polishing of a Cu surface with a diameter of 50 mm. Promising results are obtained that surface roughness and flatness are reduced from average roughness (Ra) 82 nm and peak-to-valley (PV) value 290 nm to Ra 4 nm and PV 120 nm, respectively.     

An all-fiber Fabry-Pérot interferometer for pressure sensing in different gaseous environments

A gas pressure sensor based on an all-fiber Fabry-Pérot interferometer (FFPI) is reported. The sensing head consists of a small section of silica rod spliced with a large offset between two single-mode fibers. The silica rod is used only as mechanical support so that an air cavity can be formed between both SMF. It is shown that the FFPI sensor is sensitive to gas pressure variation and when submitted to different gaseous environments, namely carbon dioxide, nitrogen and oxygen – sensitivities of 6.2, 4.1 and 3.6 nm/MPa, respectively, were attained. The refractive index change on nitrogen environment by means of gas pressure variation was also determined and a sensitivity of 1526 nm/RIU was obtained. The response of the sensing device to temperature variations in air was also studied and a sensitivity of −14 pm/°C was attained.     

Electrical assessment of commercial 6.0-kV HTV silicone rubber for power insulation

Silicone rubber has been widely used for electrical insulation in several power devices, e.g.: power insulators and metal-oxide surge arresters. In accordance with international standards, High-Temperature-Vulcanization Silicone Rubber for electrical power insulation should support 3.0 kV in electrical tracking and erosion tests, which are well established by the IEC. However, most of silicone rubbers used for manufacturing of electrical power components supports a maximum voltage of 2.75 kV. This research proposes a careful evaluation of the electrical performance of a new 6.0 kV silicone rubber developed by a worldwide-known manufacturer in the electrical power segment. The new silicone rubber is submitted to electrical tracking and erosion tests using two different approaches described in the IEC 60587: the step and steady methods. These two testing procedures are carried out in AC, following the normative recommendations, and also adapted for DC analyses. This research presents three principal contributions: a testing methodology considering both AC and DC, important conclusions on an emergent technology for electrical insulation in power systems and a quantitative analysis of erosion in polymeric composites based on the mass loss.     

Experimental characterization of biphasic materials using rate-controlled Hertzian indentation

This paper describes a new method, based on Hertzian biphasic theory (HBT), to characterize properties of biphasic materials with reduced time demands, increased surface sensitivity, and reduced computational demands compared to the current gold standards. Indentation experiments were conducted at a single location on a representative osteochondral plug to demonstrate and validate the HBT method against two gold standards, linear biphasic theory (LBT) and tension–compression nonlinear biphasic theory (TCN). The (1) aggregate moduli, (2) permeability and (3) tensile moduli from HBT, LBT, and TCN were (1) H_A=0.47, 0.47, and 0.40 MPa, (2) k=0.0026, 0.0014 and 0.0016 mm⁴/Ns, and (3) E_t=8.7, 0.46, and 10.3 MPa, respectively. The results support the HBT method and encourage its use, especially in light of its practical advantages.     

考虑样本异常值的改进最小二乘支持向量机算法

针对最小二乘支持向量机对异常值敏感、缺乏鲁棒性的情况,提出一种考虑样本异常值的改进最小二乘支持向量机算法。该算法首先通过采用局部异常因子检测算法为每个数据样本计算一个LOF因子,根据其因子值能够有效地将样本分成正常样本和异常样本,然后针对不同样本进行单独设置样本权重。其有效地保证了在降低异常样本权重的同时而不使正常样本权重受到影响,使最小二乘支持向量机在达到目标函数最优化的同时能够保证正常数据信息不丢失,以提高模型的鲁棒性。最后,通过引入"信息熵"和"平均粒距"来改进粒子群算法,将其应用于模型的参数优化。经过实验仿真表明,该算法能够有效地提高模型的鲁棒性,随着异常样本的增多,其模型精度提高大约67%。     

Low flow regime measurements with an automatic pulse tracer velocimeter (APTV) in heterogeneous aquatic environments

Cost-effective velocity measurements at lab and field scales are required for understanding and modeling the flow characteristics in aquatic environments such as constructed wetlands, coastal marshes, lakes and reservoirs. This paper presents a new measurement device—the automatic pulse tracer velocimeter (APTV) that is designed to measure water velocities for low flow regimes (0.2–5.0 cm s⁻¹) in heterogeneous aquatic environments using NaCl pulse tracer measurements. Hydraulic data collected in a laboratory-scale flume and field-scale constructed wetland were analyzed to determine velocity, directional flow and dispersion coefficients measured by using a cross-type and arc-type APTV. Acoustic Doppler velocimeters (ADVs) were used to collect calibration measurements in a hydraulic flume to gain fundamental understanding in support of field experiments. To test the effects of vegetation, four scenarios of laboratory-scale tests having both submerged and emergent artificial vegetation were conducted in a flume including; (1) no artificial vegetation (NAV), (2) submerged artificial vegetation (SAV) (3) emergent artificial vegetation (EAV), and (4) mix artificial vegetation (MAV). Directional flow detection and simulated storm event flow tests were conducted using an arc-type APTV data in the flume to gain perspectives of APTV performance in variable flow conditions. Cross-type APTV pulse data were eventually analyzed to determine dispersion coefficients based on the tracer curves. Finally APTVs were tested alongside an ADV for a three-day duration in a constructed wetland nearby the Everglades, Florida. Operating advantages of the APTV compared to other similar sensors were summarized in the end to enhance the application potential. Results indicate that APTVs are ideal device for affordable measurements of velocities in a 0.2–4.5 cm s⁻¹ range with the prediction of both velocity field, direction and dispersion coefficients, and capable of autonomous deployment and control in a sensor network.     

Improved machine tool linear axis calibration through continuous motion data capture

Machine tool calibration is becoming recognised as an important part of the manufacturing process. The current international standards for machine tool linear axes calibration support the use of quasi-static calibration techniques. These techniques can be time consuming but more importantly a compromise in quality due to the practical restriction on the spatial resolution of target positions on the axis under test. Continuous motion calibration techniques have the potential to dramatically increase calibration quality. Through taking several measurement values per second while the axis under test is in motion, it is possible to measure in far greater detail. Furthermore, since machine tools normally operate in dynamic mode, the calibration data can be more representative if it is captured while the machine is in motion. The drawback to measuring the axis while in motion is the potential increase in measurement uncertainty. In the following paper, different methods of continuous motion calibration are discussed. A time-based continuous motion solution is proposed as well as a novel optimisation and correlation algorithm to accurately fuse the data taken from quasi-static and continuous motion measurements. The measurement method allows for minimal quasi-static measurements to be taken while using a continuous motion measurement to enhance the calibration process with virtually no additional time constraints. The proposed method does not require any additional machine interfacing, making it a more readily accessible solution for widespread machine tool use than other techniques which require hardware links to the CNC. The result of which means a shorter calibration routine and enhanced results. The quasi-static and continuous motion measurements showed correlation to within 1 μm at the quasi-static measurement targets. An error of 13 μm was detailed on the continuous motion, but was missed using the standard test. On a larger, less accurate machine, the quasi-static and continuous motion measurements were on average within 3 μm of each other however, showed a standard deviation of 4 μm which is less than 1% of the overall error. Finally, a high frequency cyclic error was detected in the continuous motion measurement but was missed in the quasi-static measurement.