模糊神经网络在高层建筑横风向振动控制中的应用研究

提出了模糊神经网络方法控制高层建筑横风向风振反应。通过观测部分楼层加速度和控制力输出，建立了模糊神经网络控制器，解决了传统控制中有限的传感器数目对系统振动状态估计的困难．利用模糊神经网络控制器预测结构的控制行为，消除了闭环控制系统中存在的时滞。利用模糊神经网络控制器的自学习能力来确定模糊规则和语言变量隶属函数，解决了土木工程复杂结构模糊控制中，难于依据专家的主观经验来确定模糊控制规则和语言变量隶属函数等困难。模糊神经网络方法的优势在于算法自身的鲁棒性，处理结构非线性、参数不确定性及时变等问题的能力。通过对基准建筑的刚度不确定性分析，讨论了模糊神经网络控制器的鲁棒性。仿真分析表明，模糊神经网络控制策略能有效地抑制高层建筑的横风向风振反应，控制效果略优于LQG控制，而拥有LQG控制不具备的诸多优点。     

高压瞬变下的柴油加热数值仿真

提出一种通过加热高压油管内的柴油来降低柴油机冷起动排放和改善冷起动性能的方法.以某柴油机工作时,实测的高压油管嘴端与泵端的压力作为边界条件,建立高压油管内柴油的加热模型.运用计算流体动力学软件进行非稳态的传热数值仿真,得到油管内的温度场分布和燃油加热效果.仿真结果表明,在合适加热长度和加热温度下,可以有效提高高压油管内的柴油温度;加热长度的增加可以防止温度产生较大的波动.     

电力滤波器直流母线电压抗扰动的研究

针对传统直流母线电压PI控制时,有源电力滤波器直流母线电压受负载扰动影响较大的问题,本文提出了电压环采用双模控制结构：模糊控制器和PI控制器。直流母线电压在大范围内采用模糊控制,在小偏差范围内转换成PI调节。仿真结果表明：与传统的PI控制相比,双模控制明显的降低负载扰动情况下母线电压的波动性能。     

基于激活函数可调的改进型BP网络故障检测应用研究

神经网络方法被广泛应用在故障检测领域.针对某型航空装备供油系统故障率高,造成燃油压力波动较大这一复杂现象,文章对传统的BP网络传递函数和传递模式进行了改进,用变化的可调节函数代替固定的传递函数,构造了激活函数可调的改进型BP神经网络,提高了网络的储存能力和映射能力.建立了动态的网络结构和学习算法,用于该型故障问题的检测和诊断.仿真表明,改进后的网络收敛较快,精度较高,泛化能力强,检测效果比较理想.     

一种控制规则自调整的模糊控制器

根据模糊控制理论和实际工程经验，设计了一个控制规则能够自调整的模糊控制器，详细介绍了该模糊控制器的控制原理和运行机制，并作出了仿真。该模糊控制器控制精度高，动态和稳态性能均优于传统的PID和基本模糊控制器，且具有较好的鲁棒性和抗扰动能力。仿真和工程实践证明，该模糊控制器具有简便、稳定的优点，且易于工程实现，具有较高的工程应用价值。     

基于波恩近似的二维浅海声层析

目前的海洋声层析方法主要针对深海环境或水平不变浅海环境,对于水平剧变的二维浅海声层析问题仍未提出实用有效的方法。提出一种二维浅海声层析方法并讨论其理论可行性。其主要的思路是将一个水平变化的浅海环境等效为一个水平不变的背景环境叠加微弱的扰动,由波动方程推导出声速扰动与格林函数扰动之间的关系式,引用波恩近似解决两者之间的非线性问题,将反演过程简化为线性方程组的求解过程;后期针对该方法的局限性做进一步改进,包括引入迭代思路及使用一定的先验知识并提取经验正交函数(Empirical Orthogonal Function,EOF)。数值仿真实验说明该方法对局部的小幅度扰动甚至是孤立子内波的反演结果都具有较高的分辨率,初步验证了该方法的理论可行性。     

引入扰动补偿的多电机滑模协同控制研究

目的 解决多电机协同控制时容易受到非线性和外界扰动等不定因素的影响。方法 基于多电机偏差耦合控制结构,与引入扰动补偿的混合非奇异终端滑模变结构控制相结合,并与传统PI(Proportional Integral)调节器控制效果做仿真对比。结果 本文所提控制算法通过计算机仿真软件进行验证分析,该算法能够使得电机在启动时效果较好,转速误差在受到扰动时效果优于传统PI控制约8.50%;电机转矩在受到扰动后控制效果更加理想,几乎不存在迟滞时间就能达到新的负载转矩值;在受到负载扰动时转速误差波动较小,优于传统PI控制约8.83%。结论 通过计算机仿真验证得出,引入扰动补偿后的混合非奇异终端滑模变结构控制系统的响应时间和收敛速度、控制性能和鲁棒性都要优于传统PI控制的。     

基于小波分析的模糊控制算法应用

针对空间跟踪系统的特点及对伺服控制的技术要求,采用基于小波分析的模糊控制器,将小波基函数作为隶属函数,可根据误差在线调整隶属函数的形状,使模糊控制具有更优、更强的自适应能力。仿真与实验结果表明这种控制器比常规的PID控制器具有更好的动态性能和抗干扰能力,能很好的用于跟踪系统的控制。     

多容耦合系统模糊超前迭代压力控制设计

为研究高速列车提速后对车体材料气密疲劳性能的影响,建立车内、外压力加载试验平台,并抽象出多容耦合压力控制系统。针对多容耦合压力控制系统数学模型难以建立,且存在大时滞、非线性和多扰动等缺陷,基于超前迭代控制思想设计控制器,利用模糊控制策略对控制参数进行整定优化,实现多个容器内压力的准确控制。结合质量守恒定律、等效积分效应以及理想气体状态方程,利用Simulink的S函数建立多容耦合压力控制系统质量-压力转换数值模型并进行仿真控制研究。结果表明:该控制方法可以有效提高控制准确度,改善控制品质。     

自适应变论域模糊控制器在结构振动控制中的应用

大挠性航天结构具有复杂的动力学特性,建立其精确的数学模型是很困难的,模糊控制不需要精确的数学模型,但是模糊控制的主要缺陷是精度不太高,自适应能力有限,易产生振荡现象。变论域自适应模糊控制是改变模糊控制性能的主要方法之一,针对自适应变论域模糊控制器的稳定性设计这一难题,将输入和输出的隶属度函数分别用论域值表示成解析形式,引进李亚谱诺夫函数,设计了输入和输出的隶属度函数论域值的自适应律,针对大型航天桁架结构振动控制的仿真,结果表明设计的变论域模糊控制器是可行的。     

基于瞬时转速波动率的内燃机故障诊断方法研究

内燃机的瞬时转速包含着各个缸燃烧状态的重要信息,可以用于分析各个缸做功状态,诊断缸体点火相关故障,如燃料泄漏、气门泄漏和点火异常等故障。通过模型建立从理论上分析瞬时转速与气体压力扭矩、往复惯性力扭矩和阻力矩之间的关系,提出4个特征参数表征瞬时转速波动率波形及谐波特征,并通过仿真数据和实测故障数据证明瞬时转速波动率对于分析诊断内燃机点火故障的有效性,实现内燃机点火状态的早期预警。     

沙漠车用陶瓷活塞顶的研制

氮化硅陶瓷活塞顶是无冷机的关键部件之一．本工作选用高熔点的稀土氧化物为添加剂,在气氛加压炉内1800～1960℃,0．1～6MPaN₂压力下进行烧结,制备了性能优越的氮化硅陶瓷材料．其常温抗弯强度为750MPa,断裂韧性为7．2MPa·m^1/2,Weibull模数为12．3．使用该材料制备的氮化硅陶瓷活塞顶,装在6105型无水冷柴油机中,在规定的条件下进行耐久考核,已完成700h以上的台架实验,氮化硅陶瓷活塞顶装在EQ2060沙漠车上进行道路试验,已行驶1900km以上,经检验氮化硅陶瓷活塞顶完好无损．     

Injection Strategy in Natural Gas–Diesel Dual-Fuel Premixed Charge Compression Ignition Combustion under Low Load Conditions

Dual-fuel premixed charge compression ignition (DF-PCCI) combustion has been proven to be a viable alternative to conventional diesel combustion in heavy-duty compression ignition engines due to its low nitrogen oxides (NO_x) and particulate matter (PM) emissions. When natural gas (NG) is applied to a DF-PCCI engine, its low reactivity reduces the maximum pressure rise rate under high loads. However, the NG–diesel DF-PCCI engine suffers from low combustion efficiency under low loads. In this study, an injection strategy of fuel supply (NG and diesel) in a DF-PCCI engine was investigated in order to reduce both the fuel consumption and hydrocarbon (HC) and carbon monoxide (CO) emissions under low load conditions. A variation in the NG substitution and diesel start of energizing (SOE) was found to effectively control the formation of the fuel–air mixture. A double injection strategy of diesel was implemented to adjust the local reactivity of the mixture. Retardation of the diesel pilot SOE and a low fraction of the diesel pilot injection quantity were favorable for reducing the combustion loss. The introduction of exhaust gas recirculation (EGR) improved the fuel economy and reduced the NO_x and PM emissions below Euro VI regulations by retarding the combustion phasing. The combination of an NG substitution of 40%, the double injection strategy of diesel, and a moderate EGR rate effectively improved the combustion efficiency and indicated efficiency, and reduced the HC and CO emissions under low load conditions.     

不同海拔下涡轮增压柴油机表面辐射噪声试验研究

采用表面声压级测量法,运用大气压模拟测试系统,以4100QBZL柴油机为研究对象．测试计算涡轮增压柴油机同转速不同海拔下声功率,不同海拔不同转速下的声功率,不同转速下不同喷油提前角的声功率：分析测试结果表明：表面辐射噪声随转速增加而增大;同转速下,增压柴油机整机噪声随海拔增加而增大;以及不同转速下,喷油提前角对柴油机噪声影响规律。     

The operation of a turbulence chamber diesel engine with LPG fumigation for exhaust emissions control

An experimental study is conducted to evaluate the use of liquefied petroleum gas (LPG) as a secondary fuel for a Ricardo E-6, naturally aspirated, four-stroke diesel engine having a turbulence combustion chamber (indirect injection). The gaseous LPG is introduced together with the aspirated air (fumigation) at various proportions with respect to the diesel fuel which constitutes the main part. The influence of fuel feed ratios (LPG/diesel), in a vast range of loads, on fuel consumption, pressure diagrams, exhaust smokiness and exhaust gas emissions (nitrogen oxides, hydrocarbons and carbon monoxide) is investigated, the baseline being the single diesel fuel operation. The study for this type of engine, which has not being reported in the literature, shows a promise of the present method and reveals that above 60 per cent of maximum load the whole effect is beneficial concerning specific fuel consumption and smoke reduction. The examination of gaseous pollutant levels shows an involved relation with respect to load and fuel proportions. The best results (coupled to acceptable cylinder pressure levels) is obtained at a diesel fuel substitution value of 75% of maximum load, with an LPG mass fraction in the range 10 to 15%.     

气压烧结氮化硅陶瓷活塞顶

本工作研究了添加稀土氧化物的反应烧结氮化硅，在高氮气压力下的气氛加压烧结性能， 制备出高温性能优良的氮化硅陶瓷材料；使用此种材料研制成功了内腔为梅花型的氮化硅陶瓷活塞顶，在无水冷柴油机中规定的工艺条件下，通过４００ｈ台架耐久考核试验后，又装入大客车中，完成１２０００ｋｍ以上的道路试验。     

柴油机间歇性排气噪声自适应有源前馈控制的DSP仿真

分析了柴油机排气噪声的特征，利用自适应有源前馈系统对噪声进行控制；对间歇性噪声的控制进行了建模分析；对柴油机的排气噪声进行了有源消声的初步设计；参考柴油机实际工况，利用高速信号处理芯片TMS320F2812进行了编程及调试；通过实测数据和DSP仿真实验验证了所采用方法的有效性。     

一台高强化柴油机排气噪声有源控制实验研究

柴油机噪声使操作人员工作环境恶化,长期还危害操作人员的身体健康。排气噪声对柴油机整机噪声贡献很大,本文设计了一套自适应有源噪声控制（Adaptive Active Noise Control）系统用于控制排气噪声,实验结果表明该系统效果良好。     

Experimental analysis of fuel from fish processing industry waste in a diesel engine

In the present work, biofuel derived from industrial fish processing industry waste is used in diesel engines to study its suitability . Biofuel from industry fish waste is produced through catalytic cracking, and its quality has been improved through distillation. A single cylinder 4.5 kW at 1500 rpm was used to find the suitability of biofuel and undistilled biofuel in diesel engine. Experimental results show that the brake thermal efficiency of biofuel and undistilled biofuel is similar. Brake thermal efficiency for diesel, undistilled biofuel and biofuel is 29.98, 32.12 and 32.4%, respectively, at 80% load. Carbon monoxide, unburnt hydrocarbons, particulate matter and oxides of nitrogen emissions increase with undistilled biofuel compared to biofuel. There is a small reduction in carbon dioxide emission with undistilled biofuel compared to biofuel. Even though the cylinder pressure is high with undistilled biofuel, the intensity of premixed combustion is lower than distilled biofuel. The ignition delay and combustion duration increase with undistilled biofuel. Finally, it is concluded that the fuel derived from fish processing industry waste can be used as a fuel for diesel engine after distillation.     

Theoretical and experimental investigations of a novel hot-film anemometer for high-pressure automotive applications

A micromachined hot-film anemometer on a high-pressure stable substrate is demonstrated to be suitable for "on-board" measurements of various injection quantities, which are needed in modern direct injection systems for optimum performance of diesel, as well as gasoline, engines. To estimate the velocity profile in the injection nozzle during the injection pulse, two-dimensional finite element method calculations are performed. To consider the substrate effect on the performance of the thermal injection rate sensor, an IR imaging system is used to determine the heat loss via the robust glass ceramic substrate up to thin-film temperatures of 450 K in air. Using both the numerical and the experimental results, the temperature sensitivity and velocity sensitivity of hot-film anemometers, operated in the constant current mode in a fuel atmosphere, can be modeled analytically. Finally, an overview about the results of the latest injection rate measurements at fuel pressures up to 60 MPa and drive pulse lengths between 0.2-5 ms is given. Comparing these signals of the thermal thin-film sensor to injection volume measurements, performed with an injection amount indicator at a high-pressure hydraulic test bench, the mass flow measurements can be calibrated. One empiric parameter is necessary, which is the exponent of a power law dependence on the maximum sensor amplitude during injection.