Effectuate Application of Optimum Methods in Grinding Process

Random error of grinding process is central factor th at give an effect on grinding quality all through. Optimum methods are usually a pplied on grinding process for higher productivity and preferable grinding quali ty. But the grinding quality can’t be reliably controlled now and then while opt imal solution of grinding processing parameters have been applied in production, because of two involved aspects which are availability of established empirical formulas and reliability of setting up optimum mathematical model. That is to s ay, there is particular application of optimum methods in grinding process. This paper discussed that how to confirm conditions of grinding test which be po int to grinding peculiarity when test design and regression analysis are used to setting up some empirical formulas. In order to reduce effect of random errors on precision of the empirical formulas and enable them to be applied widely, a m ethod that a lot of random error can be sufficiently contained in grinding test was suggested. And then, A means to ameliorate restriction formulas of grinding quality is expounded based on marked level of the empirical formulas and improve d reliability of optimum mathematical model is given, which offer an effectual w ay for solving grinding quality out of control as a result of random error and w orkable optimal solution of grinding processing parameters can be applied in the production really. Finally, an example is presented.

Research of PDC Bit Compact Die With FEM and Optimum Method

In mould design, it is necessary for a designer to ensure that the cylinder has enough intensity in both the prestressed and synthesis states. An individual layer cylindrical mould cannot withstand a very high pressure needed in polycrystalline diamond composite (PDC) production. So, multi-layer prepressure combination assemble moulds are often used. The analysis conducted here is to study the interaction of cylindrical layers and to explain how to obtain enough load capability with the lowest requirement of material performance. The ratio of the pressure cylinder radius of synthetic diamond is 3.27, which is close to the optimal value and can be used as structure size in a design for PDC bit compact die. There is a linear relationship between the internal and external pressures under a special tangent stress on the inner wall of the pressure cylinder. So, when two of the three parameters (the internal pressure, external pressure, and the requirement value of the tangent stress on the inner wall of the pressure cylinder) are given, the third can be obtained. The sleeve acts as a bridge?between the pressure cylinder and the steel belts. The optimum model developed in this paper can be used in PDC bit compact die design and other similar prestressed cold extrusion die design.

OPTIMUM DESIGN BASED ON RELIABILITY IN STOCHASTIC STRUCTURE SYSTEMS

The optimum design method based on the reliability is presented to the stochastic structure systems （i. e., the sectional area, length, elastic module and strength of the structural member are random variables ） under the random loads. The sensitivity expression of system reliability index and the safety margins were presented in the stochastic structure systems. The optimum vector method was given. First, the expressions of the reliability index of the safety margins with the improved first-order second-moment and the stochastic finite element method were deduced, and then the expressions of the systemic failure probability by probabilistic network evaluation technique（PNET） method were obtained. After derivation calculus ,the expressions of the sensitivity analysis for the system reliability were obtained. Moreover, the optimum design with the optimum vector algorithm was undertaken. In the optimum iterative procedure, the gradient step and the optimum vector step were adopted to calculate. At the last, a numerical example was provided to illustrate that the method is efficient in the calculation, stably converges and fits the application in engineering.

Study of the Simultaneous Physical Retrieval Method for Meteorological Parameters over the Continental Plateau of China

It is common knowledge that continental retrieval especially for Qinghai-Xizang Plateau has not been solved todate. In order to explore applicable inverse model and method for continent including the plateau, in this study authors use an improved simultaneous physical retrieval method hereafter referred to as the ISPRM, for computing meteorological parameters from NOAA-10 satellite TOVS data. The retrieval results verified by nearby radiosondesshow that the ISPRM is more applicable for the continental plateau.

PRINCIPLES FOR OPTIMUM DESIGN OF OPEN PIT MINES

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EXPLICIT SOLUTIONS OF THE OPTIMUM WEIGHTS OF LAYERED NEURAL NETWORKS

It is shown in this paper that if the hidden layer units take a sinusoidalactivation function,the optimum weights of the three-layer feedforward neural networkcan be explicitly solved by relating the layered neural network with a truncated Fourier se-ries expansion.Based on this result,two approaches are presented of which one is suited tothe case that the detailed statistical information is available or can be easily estimated.An-other is of data-adaptive type,which can be treated as a solution of standardleast-squares.The later is best suited to realtime processing and slowly time-varying ap-plications since it can be straightforwardly implemented by the traditional LMS or RLSadaptive algorithms.It is also shown that for both the approaches,the resulting networksown an ability of forming arbitrary mappings.By using the present approaches,theconventional training procedure,which is usually very time-consuming,can be avoided.

Optimum Design for Offshore Platform Structural Reliability

In this paper, the main problems concerning reliability design of offshore platform structure are described and the general steps for the use of Safety Coefficient Method are presented.

Stress Analysis and Optimum Design of PDC Die for Offshore Drilling Engineering

The maximum internal tangential stress is a critical parameter for the design of the PDC （polycrystalline diamond compact） die that has been widely applied to offshore oil drilling. A new simple equation for the calculation of the stress is developed, and verified by the test data from Kingdream Corp. of China, the largest bit Company in China. An opti- mum method for the design of the PDC die is presented and demonstrated in detail, and software for the design and FEM analysis of the die is developed on the basis of the method. This software has been used in oil industry in recent years.

Application of Series Formula Method in Optimization Arrangement of Webs

The expressions of the internal forces of the webs under the vertical loads of the simply supported beam type trusses with vertical and horizontal webs and without vertical webs are studied through the mathematical formula method. The variations of internal forces under different angles and spacings of the webs are simulated. The law of the optimal arrangement of the webs of the parallel-string simple-beam truss is obtained: under the condition that the rigidity of the rod is allowed, the form of no vertical web-type truss and reducing the span distance and inclination of the side span are advisable, which can save materials and reduce the weight as well. This method can be applied to the calculation of internal forces for arbitrary loads and truss forms.

Robust Optimum Design of Thrust Hydrodynamic Bearings for Hard Disk Drives

This paper describes the robust optimum design which combines the geometrical optimization method proposed by Hashimoto and statistical method. Recently, 2.5″ hard disk drives (HDDs) are widely used for mobile devices such as laptops, video cameras and car navigation systems. In mobile applications, high durability towards external vibrations and shocks are essentials to the bearings of HDD spindle motor. In addition, the bearing characteristics are influenced by manufacturing error because of small size of the bearings of HDD. In this paper, the geometrical optimization is carried out to maximize the bearing stiffness using sequential quadratic programming to improve vibration characteristics. Additionally, the bearing stiffness is analyzed considering dimensional tolerance of the bearing using statistical method. The dimensional tolerance is assumed to distribute according to the Gaussian distribution, and then the bearing stiffness is estimated by combining the expectation and standard deviation. As a result, in the robust optimum design, new groove geometry of bearing can be obtained in which the bearing stiffness is four times higher than the stiffness of conventional spiral groove bearing. Moreover, the bearing has lower variability compared with the result of optimum design neglecting dimensional tolerance.

基于耦合谐振及新型空间全向耦合机构的无线电能传输系统

针对传统无线电能传输系统中发射机构和接收机构相对位置发生偏移时,传输功率和效率急剧下降的问题,提出了一种基于耦合谐振及新型空间全向耦合机构的无线电能传输系统。首先通过有限元仿真分析发射机构的磁场分布特性,设计了适应其磁场分布的接收机构;然后基于串串谐振补偿结构建立系统数学模型,分析系统传输特性;在此基础上提出了最优输出方式选择方法和传输特性优化方法。最后,通过试验验证了所提系统多自由度传输能量的可行性和有效性。试验结果表明,接收机构在多角度情况下的输出功率维持在35 W以上,传输效率稳定在60%~75%。

Optimum design of welding transformer

Welding transformer is widely used in industry manufacturing, depleting a large portion of electricity energy.Based on modern computer technology and mathematical programming, optimum design of electro-magnetic devices leads to highly efficient use of energy and materials. Are welding transformer is optimized here. A mathematical model,considering both productive cost and operating losses, which is called or Economical-through-Life transformer, is established. Mixed penalty function method, mixed dispersing variable method and improved orthogonal method have been applied to carry out the optimization calculations. Result shows that the power factor is quite important in an Economi-cal-through-Life transformer, and that some principles must be followed in the design work. Also discussed are the advantages and disadvantages of the three methods. In the end, the prospect of optimum design of welding transformer is forecast.

腔内ECG定位技术联合体外测量法在PICC中的应用

目的:探讨腔内心电图(ECG)定位技术联合体外测量法在经外周静脉穿刺的中心静脉导管(PICC)中的应用。方法:选取2021年1月—2023年1月阜宁县人民医院收治的100例行上肢PICC置管的患者作为研究对象。根据抛币法将其随机分为观察组和对照组,各50例。两组均进行PICC,对照组PICC应用体外测量法,观察组PICC应用腔内ECG定位技术联合体外测量法。比较两组一次性置管情况、导管相关并发症、置管满意度。结果:观察组置管准确率为98.00%,高于对照组的86.00%,置管过深率低于对照组,差异有统计学意义(P<0.05)。两组并发症发生率比较,差异无统计学意义(P>0.05)。观察组总满意度为100%,高于对照组的92.00%,差异有统计学意义(P<0.05)。结论:腔内ECG定位技术联合体外测量法可提高一次置管准确率,提高患者满意率。

基础隔震结构附加变化型调谐质量惯容阻尼器的优化设计研究

在强震作用下基础隔震结构的隔震层将发生非常大的水平变形。已有研究表明采用在基础隔震结构的隔震层附加变化型调谐质量阻尼器(VTMD)的混合控制策略能够有效降低隔震层的水平变形需求,然而该混合控制策略最大的缺陷在于需要很大的调谐质量。考虑到惯容装置具有明显的质量放大效应,本文提出将惯容装置(Inerter)与VTMD中的阻尼器并联,从而形成具有较小调谐质量的变化型调谐质量惯容阻尼器(VTMDI),并将其附加在基础隔震结构的隔震层,基于随机振动的分析框架开展了VTMDI参数的优化设计研究。研究表明直接将基础隔震结构的上部结构层间变形作为优化目标的传统优化策略并不经济有效。为此,本文提出了一种基于两步优化法的优化策略,该优化策略首先确保附加VTMDI的基础隔震结构相对于附加相同阻尼的基础隔震结构具有更优的控制效果;然后确保附加VTMDI的基础隔震结构的上部结构层间变形最小。通过动力时程分析结果表明:两种优化策略都能有效降低隔震层的水平变形和上部结构的层间变形,同时不会导致调谐质量出现过大的运动行程,基于两步优化法的优化策略更为经济有效。

响应面优化超声提取绿色棉纤维总黄酮

【目的】优化超声提取绿色棉纤维中总黄酮工艺条件,为合理利用及鉴别天然绿色棉纤维提供依据。【方法】以天然绿色棉纤维为原料,利用超声空化效应加速黄酮溶解于乙醇中,在单因素试验基础上,结合Box-Benhnken中心组合原理及响应面设计优化试验条件。【结果】料液比为1∶50 g/mL时,总黄酮得率达到最大值,提取最适料液比为1∶50 g/mL,响应面试验中建立的模型的CV值=0.87%,影响绿色棉纤维总黄酮得率的顺序为提取时间>乙醇浓度>料液比,A料液比为1∶50 g/mL、B乙醇浓度50%、C提取时间50 min为最佳提取条件。【结论】超声波法提取绿色棉纤维总黄酮的最佳条件参数为料液比1∶50 g/mL、乙醇浓度50%、提取时间50 min;获得平均总黄酮得率为5.25%。

Optimization of the gas separation performance of polyurethane–zeolite 3A and ZSM-5 mixed matrix membranes using response surface methodology

In the present work, the response surface method software was used with five measurement levels with three factors.These were applied for the optimization of operating parameters that affected gas separation performance of polyurethane–zeolite 3A, ZSM-5 mixed matrix membranes.The basis of the experiments was a rotatable central composite design(CCD).The three independent variables studied were: zeolite content(0–24 wt%), operating temperature(25–45 ℃) and operating pressure(0.2–0.1 MPa).The effects of these three variables on the selectivity and permeability membranes were studied by the analysis of variance(ANOVA).Optimal conditions for the enhancement of gas separation performances of polyurethane–3A zeolite were found to be 18 wt%, 30 ℃ and 0.8 MPa respectively.Under these conditions, the permeabilities of carbon dioxide, methane, oxygen and nitrogen gases were measured at 138.4, 22.9, 15.7 and 6.4 Barrer respectively while the CO_2/CH_4, CO_2/N_2 and O_2/N_2 selectivities were 5.8, 22.5 and 2.5, respectively.Also, the optimal conditions for improvement of the gas separation performance of polyurethane–ZSM 5 were found to be 15.64 wt%, 30 ℃ and 4 bar.The permeabilities of these four gases(i.e.carbon dioxide, methane, oxygen and nitrogen) were 164.7, 21.2, 21.5 and 8.1 Barrer while the CO_2/CH_4, CO_2/N_2 and O_2/N_2 selectivities were 7.8, 20.6 and 2.7 respectively.

Generalized Method of Moments and Generalized Estimating Functions Using Characteristic Function

GMM inference procedures based on the square of the modulus of the model characteristic function are developed using sample moments selected using estimating function theory and bypassing the use of empirical characteristic function of other GMM procedures in the literature. The procedures are relatively simple to implement and are less simulation-oriented than simulated methods of inferences yet have the potential of good efficiencies for models with densities without closed form. The procedures also yield better estimators than method of moment estimators for models with more than three parameters as higher order sample moments tend to be unstable.

基于改进ADMM的含分布式光伏的配电网电压无功优化方法

由于所建立含分布式光伏(PV)的有源配电网电压无功优化模型是一个典型的非凸混合整数非线性优化模型,提出一种改进交替方向乘子法(ADMM)来求解含分布式光伏的配电网电压无功优化问题。首先以有载调压变压器和投切电容器组为例,建立一种新的广义可分解有源配电网电压无功优化模型,然后根据ADMM算法将有源配电网电压无功优化模型分解为2个子问题求解,并设计惩罚参数的自适应调节机制以加速收敛。在3个不同规模有源配电网算例上进行仿真测试,结果表明,所提出改进ADMM方法具有较好的收敛性和最优解。

基于3414试验设计的云南雪茄烟叶生产施肥技术研究

为明确云南省瑞丽雪茄烟区土壤合理施肥方案,采用“3414”肥料试验设计,通过熵权法和回归分析,计算了各处理对应的烟株农艺性状综合得分,探究了N、P、K对雪茄烟株长势和烟叶产量的影响,筛选出最佳施肥方案。结果表明:(1)株高对雪茄烟株农艺性状的得分所占权重最大,处理6(N_(2)P_(2)K_(2))对应的得分最高。(2)在一定范围内增加N、P、K的施用量,对雪茄烟的产量有积极作用,然而随着施肥量的增加产量又有所下降。(3)构建了N、P、K施用量对雪茄烟产量的二元二次和三元二次回归模型,最佳施肥方案为N施用量在118.7~126.9 kg/hm^(2)之间,P_(2)O_(5)施用量在75.7~81.4 kg/hm^(2)之间,K_(2)O施用量在342.1~366.5 kg/hm^(2)之间,目标产量在1816.3~1812.5 kg/hm^(2)之间。

基于CFD与田口方法的H型垂直轴风力机气动性能优化

风力机结构优化对提高能源转换效率至关重要。为低成本探究叶片数量(n)、半径(R)、展弦比(μ)和安装角(β)四个结构参数对垂直轴风力机气动性能的影响,采用基于田口方法的正交试验设计和改进的加性模型,确定了使风力机功率输出最大化的最优设计参数,并进行了CFD数值验证研究。结果表明,利用田口法结合改进的加性模型,能够准确确定最优的参数组合及各因素对其气动性能的影响程度。分析得出在n=3、R=2.5 m、μ=8、β=-3°时,风力机性能最强;而在n=5、R=1.0 m、μ=5、β=0°时性能最弱。与最差构型相比,最优构型的平均功率系数提升了66.12%;四个因素对垂直轴风力机效率的影响程度大小为R>n>β>μ。