Structure Parameters Optimization Analysis of Hydraulic Hammer System

In order to improve the impact performance, the structure of hydraulic hammer should be optimized. In this paper, the ranges of eight vital structure parameters of piston and reversing valve system of hydraulic hammer were selected firstly;and then found the best value of different parameters under experiments with the method of computer optimization and the parametric analysis method provided by ADAMS software. These methods worked and the best design values of parameters of hydraulic hammer were obtained. At last, the optimal impact energy of virtual prototype of hydraulic breaking hammer was calculated and compared with the original impact performance. The results reveal that impact performance of hydraulic hammer has been improved significantly.

Effect of calibration data series length on performance and optimal parameters of hydrological model

In order to assess the effects of calibration data series length on the performance and optimal parameter values of a hydrological model in ungauged or data-limited catchments (data are non-continuous and fragmental in some catchments),we used non-continuous calibration periods for more independent streamflow data for SIMHYD (simple hydrology) model calibration.Nash-Sutcliffe efficiency and percentage water balance error were used as performance measures.The particle swarm optimization (PSO) method was used to calibrate the rainfall-runoff models.Different lengths of data series ranging from one year to ten years,randomly sampled,were used to study the impact of calibration data series length.Fifty-five relatively unimpaired catchments located all over Australia with daily precipitation,potential evapotranspiration,and streamflow data were tested to obtain more general conclusions.The results show that longer calibration data series do not necessarily result in better model performance.In general,eight years of data are sufficient to obtain steady estimates of model performance and parameters for the SIMHYD model.It is also shown that most humid catchments require fewer calibration data to obtain a good performance and stable parameter values.The model performs better in humid and semi-humid catchments than in arid catchments.Our results may have useful and interesting implications for the efficiency of using limited observation data for hydrological model calibration in different climates.

Multi-objective Optimization of Geothermal Extraction from the Enhanced Geothermal System in Qiabuqia Geothermal Field, Gonghe Basin

A geothermal demonstration exploitation area will be established in the Enhanced Geothermal System of the Qiabuqia field, Gonghe Basin, Qinghai–Xizang Plateau in China. Selection of operational parameters for geothermal field extraction is thus of great significance to realize the best production performance. A novel integrated method of finite element and multi-objective optimization has been employed to obtain the optimal scheme for thermal extraction from the Gonghe Basin. A thermal-hydraulic-mechanical coupling model(THM) is established to analyze the thermal performance. From this it has been found that there exists a contraction among different heat extraction indexes. Parametric study indicates that injection mass rate(Q_(in)) is the most sensitive parameter to the heat extraction, followed by well spacing(WS) and injection temperature(T_(in)). The least sensitive parameter is production pressure(p_(out)). The optimal combination of operational parameters acquired is such that(T_(in), p_(out), Q_(in), WS) equals(72.72°C, 30.56 MPa, 18.32 kg/s, 327.82 m). Results indicate that the maximum electrical power is 1.41 MW for the optimal case over 20 years. The thermal break has been relieved and the pressure difference reduced by 8 MPa compared with the base case. The optimal case would extract 50% more energy than that of a previous case and the outcome will provide a remarkable reference for the construction of Gonghe project.

Blade Shape Optimization of Liquid Turbine Flow Sensor

Based on the characteristic curve analysis, the method using D(K^2) square difference of meter factor at different flow rates was developed to evaluate the performance of turbine flow sensor in this study. Then according to the distribution of entrance velocity, it was supposed that reducing the blade area near the tip could decrease the linearity error of a sensor. Therefore, the influence of different blade shape parameters on the performance of the sensor was investigated by combining computational fluid dynamics(CFD)simulation with experimental test. The experimental results showed that, for the liquid turbine flow sensor with a diameter of 10 mm, the linearity error was smallest, and the performance of sensor was optimal when blade shape parameter equaled 0.25.

Parametric Optimization of Organic Rankine Cycle with R245fa/R601a as Working Fluid

In order to select the appropriate working fluids and optimize parameters for medium-temperature geothermally-powered organic Rankine cycle(ORC), R245 fa is mixed with R601 a at geothermal water temperature of 110 ℃. Based on thermodynamics, the characteristics of mixture and its influence on the performance of ORC under different evaporating temperatures and composition proportions are analyzed. Results show that the zeotropic mixture R245fa/R601a(0.4/0.6) has the highest performance. When the evaporating temperature reaches 67 ℃, the outlet temperature of geothermal water is 61 ℃, the net power output is the highest and the thermal efficiency is about 9%.

Fault-tolerant control systems design via subdivision of parameter region

This paper presents a linear matrix inequality(LMI) approach to solve the fault-tolerant control(FTC) problem of actuator faults.The range of actuator faults is considered as a parameter region and subdivided into several subregions to achieve a certain desired performance specification.Based on the integral quadratic constraint(IQC) approach,a passive fault-tolerant controller for the whole fault region and multiple fault-tolerant controllers for each fault subregion are designed for guaranteeing stability and improving performance of the FTC system,respectively.According to the estimation of parameters by FDI process,the corresponding subregion controller is chosen for the stability and optimal performance of closed-loop systems when the fault occurs.The case of incorrect estimation is also considered by comparing the performance index between the switched controller and the passive fault-tolerant controller.The proposed design technique is finally evaluated in the light of a simulation example.

Performance improvement of licklider transmission protocol in complex deep space networks based on parameter optimization

A reasonable parameter configuration helps improve the data transmission performance of the Licklider Transmission Protocol(LTP).Previous research has focused mainly on parameter optimization for LTP in simplified scenarios with one to two hops or multihop scenarios with a custody mechanism of the Bundle Protocol(BP).However,the research results are not applicable to communications in Complex Deep Space Networks(CDSNs)without the custody mechanism of BP that are more suitable for deep space communications with LTP.In this paper,we propose a model of file delivery time for LTP in CDSNs.Based on the model,we propose a Parameter Optimization Design Algorithm for LTP(LTP-PODA)of configuring reasonable parameters for LTP.The results show that the accuracy of the proposed model is at least 6.47%higher than that of the previously established models based on simple scenarios,and the proposed model is more suitable for CDSNs.Moreover,the LTP parameters are optimized by the LTP-PODA algorithm to obtain an optimization plan.Configuring the optimization plan for LTP improves the protocol transmission performance by at least 18.77%compared with configuring the other parameter configuration plans.

Evaluation of Operating Domains in Power Systems

This paper presents the results of a recent major industry-supported study with the aim to provide power system operators with more meaningful and effective means to quickly identify feasible operating boundaries as well as more flexibility to select alternate operating scenarios. In this regard, the paper outlines the main theoretical basis and computational framework for the development of innovative computerized schemes capable of identifying and processing various system integrity domains. The novel framework allows system operators to determine – in a fast and reliable manner – the most favorable operating scenarios which maintain system security, reliability and operating performance quality. For demonstration purposes, and without loss of generality, an emphasis is given to the dynamic system security problem where the Transient Energy Function (TEF) method is used to define quantitative measures of the level (degree) of system security for a given operating scenario. Nonetheless, the framework presented is applicable quite as well to other system performance functions and criteria that may be considered. A demonstrative application is presented for a 9-bus benchmark system, widely used in the literature. In addition, a practical application is also presented for the Saudi Electricity Company (SEC) power system where the operating security domain was evaluated in the operating parameter space spanned by two major interface flows in the system.

A Prediction Method for TBM Cutterhead Dynamic Tunneling Performance under Typical Composite Geological Conditions

The cutterhead system is a core component of TBM equipment,which works in the extremely severe environment,and the strong impact loads result in severe vibration,crack,damage failure and other engineering failures.Accordingly,the key for cutterhead system structure design and parameter matching is to evaluate and predict cutterhead tunneling per-formance reasonably.In this paper,a prediction method for TBM cutterhead dynamic tunneling performance is pro-posed under the typical composite geological conditions,based on the CSM model of multi-cutters and cutter loads field test data.Then an actual TBM cutterhead of a water conservancy project is taken as an example,a spatial three-dimensional separation zone model for cutterhead tunneling is established under the typical geological condition,and the parameters influence rules of cutterhead tunneling performance are analyzed.The results show that,the cutter-head loads and specific energy change rules with different parameters are basically similar.Moreover,under the condi-tion of penetration p=10mm,the cutterhead bending moment coefficient of variation magnitude exceeds 20%,which is the maximum,and the normal cutter spacing optimal value is 95mm.Also,when the normal cutter spacing is kept constant in 85mm,the penetration has a greater influence on the torque and specific energy coefficient of variations,which is increased from 2mm to 10mm,and the two indexes decrease by about 73%.It is indicated that proper increase of pene-tration is beneficial to reduce the vibration fluctuation degree of torque and specific energy.The proposed method of TBM cutterhead dynamic tunneling performance and the analysis results can provide theoretical basis and design refer-ence for TBM cutterhead layout and tunneling parameters matching.

Optimization and comparative performance analysis of conventional and desiccant air conditioning systems regenerated by two different modes for hot and humid climates:Experimental investigation

A desiccant air conditioning system is considered a capable alternative to a conventional air conditioning system because of its independent control of temperature,humidity and being eco-friendly.Also,to resolve the problem of more energy consumption for the restoration of a desiccant,structures comprising of desiccant can utilize thermal energy or complete waste heat to revive desiccant material.Therefore,this research work executes an experimental,optimization and comparative examination for conventional and desiccant air conditioning sys-tems regenerated by two different modes,i.e.firstly using(Mode-I)complete waste heat from condenser and secondly using(Mode-II)rod(electric heater)heat for regeneration at different process air inlet temperatures,i.e.(28,29.5,31,32.5,34,35.5 and 37°C),at different process air inlet velocities,i.e.(1.5,2.5,3.5 and 4.5 m/s)and a fix(2.5 m/s)regeneration air inlet velocity.Thus,optimization of performance parameters,i.e.VCOP,ECOP,dehumidification effectiveness,moisture removal capacity(kg/hr),DCOP,regeneration effectiveness and regeneration rate(kg/hr),is identified for achieving maximum efficiency of conventional and desiccant air con-ditioning systems under the above operating conditions.

高速S-CO_(2)向心透平几何参数优化及变工况特性分析

透平是热力循环中实现热功转换的核心设备,优化透平几何参数以改善气动性能,是提升系统热效率的关键。该文以面向某船舶主机烟气余热利用的超临界二氧化碳布雷顿循环透平设计参数为基础,给出向心透平主要几何参数,采用耦合CO_(2)真实物性参数的CFX仿真方法,分析几何参数动、静叶包角以及叶轮出口几何角对透平性能的影响规律并进行参数优化,进一步研究非设计工况下的透平运行特性。结果表明:增大静叶包角会使动叶前缘出现扰动涡流并减少余速损失,增大叶轮出口几何角,动叶包角对透平效率的影响规律不变,但效率峰值点会沿动叶包角减小的方向移动;动、静叶包角和叶轮出口几何角分别为49°、21.5°、25°时透平设计点总-静等熵效率高达87.99%,相比优化前,提高0.54个百分点;透平偏离设计点±20%工况下等熵效率大于80%。结果可为超临界二氧化碳高速向心透平设计提供一定参考。

斯特林机帽式密封性能分析及回归参数优化设计

为改善斯特林机活塞杆帽式密封性能,首先采用数值仿真分析了5 MPa工质压力下其静、动态力学特性,从而获取了O型圈内径尺寸L_(N)、C型环径向壁厚T和装配过盈量S这3个关键结构参数对密封性能的影响规律。在此基础上,利用回归设计法以配伍面最大接触压力平稳且密封可靠为优化目标,对密封结构的上述3个关键参数进行优化设计以确定其最佳匹配方案,最后通过密封试验台验证了本文优化设计方法的准确性和普适性。结果表明:活塞杆与C型环密封面中间区域上最大接触压力随L_(N)和S的增大而增大,但随T的增大而减小;通过估计回归系数和方差分析(ANOVA)发现,L_(N)对密封性能影响最为显著、S次之、T影响最小;L_(N)和T、L_(N)和S交互项对响应显著,而T和S交互项对响应不显著;当L_(N)为13.745 mm、T为0.40 mm和S为0.020 mm时,优化密封件对应的正行程最大接触压力为9.01 MPa、回程为9.75 MPa,较工程在用密封件(L_(N)=13.780 mm、T=0.50 mm、S=0 mm)最大接触压力分别降低了14.7%和25.5%。实验进一步验证了优化密封件的密封性能和使用寿命均优于工程在用密封件,并且在不同工质压力下优化密封件的接触压力均匀性更好,减摩延寿效果显著,充分证明本文性能分析与优化设计方法准确有效。

脑出血患者血肿扩大的CT征象、参数表现及其相关的影响因素模型构建

目的 探讨脑出血(ICH)患者血肿扩大(HE)的电子计算机断层扫描(CT)征象、参数表现及其相关的影响因素,并构建模型。方法 对于2020年1月~2023年1月在湖北省潜江市中心医院接受治疗的124例ICH患者的临床资料进行回顾性分析,将发生HE的患者纳入HE组(59例),未发生HE的患者纳入无HE组(65例)。比较两组一般资料、CT征象、参数表现,并予以多因素Logistic回归分析法分析ICH患者HE的危险因素,构建预测模型,绘制受试者工作特征(ROC)曲线分析其对ICH患者HE的预测价值。结果 HE组入院时格拉斯哥昏迷量表(GCS)评分低于无HE组;基线血肿量、全血NPR水平均高于无HE组;初诊血肿体积、高低密度差大于无H E组;岛征、漩涡征、黑洞征、混合征及联合征象的患者占比分别为40.68%、44.07%、35.59%、52.54%及83.05%,均高于无HE组的7.69%、7.69%、4.62%、 9.23%及20.00%(P<0.05)。多因素Logistic回归分析结果显示,ICH患者HE的独立危险因素包括全血NPR水平高、初诊血肿体积大、高低密度差大、岛征、漩涡征、黑洞征、混合征及联合征象(OR=1.575、2.406、1.408、1.929、2.713、2.784、2.195、2.633,P<0.05)。构建回归方程模型:logit(P)=-8.983+全血NPR水平×0.454+初诊血肿体积×0.878+高低密度差×0.342+岛征×0.657+漩涡征×0.998+黑洞征X1.024+混合征×0.786+联合征象×0.968。ROC曲线显示,当logit(P)>12.41时,曲线下面积(AUC)值为0.824,95%CI为0.746~0.887,χ^(2)为8.848,诊断敏感度为79.66%,特异度为73.85%。结论 ICH患者HE的独立危险因素包括全血NPR水平高、初诊血肿体积大、高低密度差大、漩涡征、岛征、混合征、黑洞征及联合征象,预测模型对其预测价值较高,临床尽早结合上述情况进行评估,并给予针对性干预措施,有助于预防ICH患者HE的发生风险。

Performance test and process parameter optimization of 9FF type square bale straw crusher

In order to solve the problem of low productivity,unqualified segment length and high energy consumption during the process of crushing square bale straw caused by improper operation parameters,a 9FF square bale straw crusher was developed.In this study,by taking maize straw as the test material,the feeding speed,spindle speed of the crushing device and the state of the crushing device were taken as influence factors,and standard straw length rate,productivity per net working hour(hereinafter referred to as NWH)and energy consumption per ton of product as test indicators,the influence of the factors on the indicators were studied,and tests were carried out on the process of square bale straw crushing.By adopting the single factor test on the effect of the feeding speed,the spindle speed of the crushing device and the state of the crushing device on the test indicators,the suitable range of each factor was determined,respectively.Using the orthogonal test method,range method,variance method and comprehensive balance method,the experiment analyzed the significance of the influence of the three factors on various indicators and the order of priority.The test results showed that:the feeding speed was 5 m/min,spindle speed was 3000 r/min,and the state of the crushing device was a mixing cutter hammer,which was the best parameter combination(A1B1C1)for the processing technology of the square bale forage crusher.The standard straw length rate was 93.7%,and the productivity per NWH was 2.80 t/h,with energy consumption per ton of 4.72 kW·h/t,in which the standard straw length rate and productivity per NWH reached optimal values,and the energy consumption per ton of product was slightly higher than the optimal value in the experiment.The research results can provide a reference for the optimal design of the special crusher for square bale straw.

15 nm Bulk nFinFET器件性能研究及参数优化

为研究Bulk FinFET工作时基本结构参数、器件温度和栅极材料对其性能的影响,建立了一个15 nm n型Bulk FinFET器件模型,仿真分析了不同栅长、鳍宽、鳍高、沟道掺杂浓度、器件工作温度、栅极材料对器件性能的影响,发现增长栅长、降低鳍宽和增加鳍高有助于抑制短沟道效应;1×10^(17)cm^(-3)以下的低沟道掺杂浓度对器件特性影响不大,但高掺杂会使器件失效;器件工作温度的升高会导致器件性能的下降;采用高K介质材料作为栅极器件性能优于传统材料SiO_(2)。

舰船水下抗爆U型夹层板结构改进及参数优化设计

设计相应的防护结构来降低水下爆炸冲击荷载对舰船的损伤对于提高舰船生命力具有重要意义.以U型夹层板为研究对象,对传统U型夹层板结构进行改进,提出了3种改进的U型夹层板结构.采用有限元软件LS-DYNA中任意拉格朗日-欧拉(ALE)算法分析水下爆炸冲击荷载作用下3种改进夹层板的位移、速度与加速度响应和吸能效应,并与原始U型夹层板对比找到综合性能相对最优的改进夹层板.最后通过正交试验对性能最优的夹层板进行优化,分析夹层板设计参数对抗爆性能影响的主次顺序及最优的尺寸组合.分析表明:改进的U-X型夹层板上面板位移相比U型夹层板下降了15.7%,速度下降了34.5%,芯层吸能提高了25.2%,在改进夹层板中综合性能最优;U-X型夹层板最优的尺寸组合及设计参数为芯层厚度1.5 mm、芯层高度100 mm、下面板厚度3.0 mm、上面板厚度3.5 mm.经验证,尺寸优化后U-X型夹层板质量降低了6.3%,抗爆性能也得到了显著提高.

Influence of the layer parameters on the performance of the CdTe solar cells

Influence of the layer parameters on the performances of the CdTe solar cells is analyzed by SCAPS-1 D. The Zn O: Al film shows a high efficiency than SnO_2:F. Moreover, the thinner window layer and lower defect density of Cd S films are the factor in the enhancement of the short-circuit current density. As well, to increase the open-circuit voltage, the responsible factors are low defect density of the absorbing layer CdTe and high metal work function. For the low cost of cell production, ultrathin film CdTe cells are used with a back surface field(BSF) between CdTe and back contact, such as PbTe. Further, the simulation results show that the conversion efficiency of 19.28% can be obtained for the cell with 1-μm-thick CdTe, 0.1-μm-thick PbTe and 30-nm-thick CdS.

基于相关性分析和响应面法的复合旋流器结构参数优化

为了提高旋流器优化参数的准确性,得到其在结构优化中的最优解,以一种新型复合旋流器为研究对象,基于相关性的单因素分析寻优法,以相关性分析的结果来指导优化范围的选取,提高其结构参数优化范围的准确性。结合响应面优化方法,以分离效率为优化目标,确定旋流器的最优结构参数,建立了分离效率和结构参数之间的回归模型。结果表明:不同的结构参数和各性能指标之间的显著关系并不相同,根据相关性分析的结果确定各结构的优化范围为:上锥角为0°~4°,下锥角为8°~12°,底流口直径为12~16 mm;响应面优化得到旋流器最优结构为:上锥角为2.565°,下锥角为11.719°,底流口直径为12.889 mm,在本组参数下旋流器固体分离效率达到了99.945%,气体分离效率达到了93.807%。为旋流器的结构优化提供了一种新方法。

2-DOF并联行程放大机构结构参数优化

为研制一种能实现快速行走、运动灵活性好的仿生四足机器人,对一种能够实现机构末端位置行程放大的2自由度并联机构进行运动性能分析与结构参数优化,并将优化结果应用到仿生四足机器人的腿部机构,研制出样机。首先,推导2自由度并联行程放大机构位置反解,建立机构的线速度雅克比矩阵,对机构的工作空间进行分析。其次,建立机构运动灵活性能评价指标,揭示主要结构参数对灵活性能指标的影响规律。然后,采用容限加权法确定一组合理的结构参数,使运动灵活性能指标达到最优。最后,根据优化的结构参数设计出仿生四足机器人腿部机构和整体的虚拟样机,并进行虚拟样机运动仿真。仿真结果表明:并联行程放大机构各驱动参数变化平稳,理论速度和仿真速度误差在±1.6×10-6m/s范围内,验证仿生四足机器人腿部机构设计方案和结构参数的合理性及理论推导的正确性,为该仿生四足机器人的进一步研究奠定了基础。

基于定子全浸式及绕组内冷式的蒸发冷却永磁直驱风力发电机优化设计研究

为了充分发挥蒸发冷却技术在风力发电领域中高效的散热性能以及免维护的自循环特性,本文基于发电机定子全浸泡以及绕组空心导线内冷的两种散热形式,对一系列不同功率等级下的直驱式永磁风力发电机进行了优化设计研究,并对不同冷却技术路线下的电机优化设计方案进行了对比和分析。本文首先分析了不同技术路线下不同蒸发冷却系统各自所具有的特点及优势;之后基于电磁场和传热学理论建立了发电机电磁参数及温度场的分析计算模型,并基于冷却系统的结构布局分析了不同技术路线下发电机定子的传热特性;最后基于发电机电磁场和温度场的耦合分析建立了风力发电机的优化设计模型,通过多目标遗传优化算法,对2MW、5MW和10MW三种不同功率等级下的直驱式永磁风力发电机进行了以材料和成本为目标的电机系统优化设计。优化结果及对比分析表明,针对兆瓦级直驱式风力发电机而言,采用空心导线内冷式技术更具有设计成本和冷却性能上的优势,本文中的优化方法和策略可以为蒸发冷却永磁直驱式风力发电机的优化设计提供理论依据和设计基础。