难加工材料切削用量可优化区间的限定

针对传统切削用量优化方法在自动化程度较高以及大量使用难加工材料领域时局限,对刀具磨损随切削用量的变化趋势与广义刀具耐用度公式和马卡洛夫最优切削速度公式两种数学模型的符合程度进行比较,分析基于两种数学模型的优化方法的适用性和限制,提出使用磨损指数确定切削用量可优化区间边界条件的方法,分析多项切削用量可优化区域的特点.     

车铣切削用量优化方法研究

针对车铣复合加工的切削用量优化的问题,阐述了车铣复合加工技术的特点和应用情况,详细地描述了国内的研究现状,以及车铣复合加工切削用量优化的研究思路、方法和结论。采用以最大生产效率和最大利润率为双目标,根据已建立的车铣复合加工切削用量的数学模型和约束条件,详细分析了现代各个优化算法的特点,并结合车铣切削用量优化计算的特征,选用了遗传算法。     

复杂型面微小零件精密切削工艺研究

在自研的微小零件精密加工机床上,通过分析复杂型面造型技术、刀具路径规划方法和切削用量优化选择,开展了金属材料复杂形面微小零件的精密切削工艺研究,加工出了硬铝材料制作、典型的高精度复杂形面微小零件样件。     

镁合金高速切削条件下表面粗糙度影响因素析因分析

为研究镁合金在高速切削条件下切削用量和刀具形状对已加工表面粗糙度的影响规律,综合应用析因与均匀试验设计,以一定的切削用量和一定的刀具对Mg-Al-Zn-Mn系镁合金进行了高速车削试验,并结合回归统计与响应曲面方法建立了表面粗糙度Ra经验公式。     

铣削30CrMnSiNi2A钢刀具耐用度影响研究

本文通过对涂层硬质合金刀具铣削30CrMnSiNi2A钢时切削力和刀具耐用度的研究,以及冷却方式对刀具耐用度影响的分析,为切削该材料选择合理的切削用量和冷却方式提供指导,并为切削参数的优化提供约束条件。     

高速铣削高强度钢时切削力影响因素析因与偏回归研究

研究了一定范围内高速端面铣削某新型高强度钢材料(>HRC42,抗拉强度σb>1.2GPa)过程中切削力的变化规律,并从切削变形机理上进行讨论与分析。通过L8(23)析因分析与偏回归分析,考察切削用量对铣削力的交互影响规律,使用残差分析与最小二乘法等统计方法,建立切削力与切削用量经验公式。     

切削加工优化研究

本文通过切削加工机理的研究，建立了切削加工的数学模型，为难加工材料切削用量的选择提供了科学的方法。     

碳纤维复合材料切边加工实验研究

通过实验研究了不同切削用量下刀具的磨损规律,建立了刀具切削长度与切削用量之间的关系模型,并获得了切削力随刀具切削路程单调递增变化的规律,优选出了一组刀具寿命较长的切边参数。同时,还针对铣削切边方法对刀具锋利程度要求较高的问题研究了利用磨削方式实现切边加工加工的新途径,通过实验验证了磨削加工方式可大幅度降低切边加工成本,是一种较好的切边加工方式。     

起落架复杂箱体零件加工工艺研究

在加工超高强度复杂箱体类零件的过程中,研究其加工工艺,明确编制合理的制造工艺流程、选择合适的装夹定位方案、有效利用车间资源和切削刀具、分析件热后的变形规律并加以控制、设定合理的切削用量、引入曲线插补优化刀轨是保证复杂箱体类零件加工质量和提高生产效率的重要途径。     

单晶硅超精密切削加工表面粗糙度预测模型的建立及试验研究

利用超精密机床进行切削加工时,对于操作者来说,首先面临的问题是最优切削用量组合的确定,这也是最让操作者感到棘手的问题.单晶硅成功的切削过程取决于优化工艺参数,比如进给量、背吃刀量、切削速度等.为了建立精确可靠的表面粗糙度预测模型,本文将遗传基因算法应用于回归分析,同时在超精密机床上对该预测模型进行了试验验证.     

On adaptive spatial-temporal processing for airborne surveillanceradar systems

Implementing the optimum spatial-temporal (angle-Doppler) processor involves two crucial issues: the selection of processing configurations, and the development of adaptive algorithms which can efficiently approach the performance potential of the selected configuration. Among the three available configurations, the joint-domain, the cascade space-time, and the cascade time-space, this work shows that, in contrast to a popular belief, the detection performance potentials of both cascade configurations can fall far below that of the joint-domain optimum. In addition, this work presents a new adaptive algorithm, called the Joint-Domain Localized Generalized Likelihood Ratio detection (JDL-GLR), which is data efficient i.e., with fast convergence to the joint-domain optimum, as well as computationally efficient, together with such desirable features as the embedded constant false-alarm rate (CFAR) and robustness in non-Gaussian interference     

民机机身下部结构耐撞性优化设计

 针对含多设计参数的典型民机机身下部结构耐撞性设计,提出了一种设计方法,该方法以最小化客舱地板的初始加速度峰值与最大化参考压溃状态的结构内能为优化双目标,通过Kriging模型对结构的冲击响应进行预测,采用非支配排序遗传算法II(NSGA-II)对双目标进行优化,进而由Nash-Pareto策略获得最优方案。为了得到最优设计方案,同时研究设计参数对机身结构耐撞性的影响,提出最大化期望提高与最大化预测方差同步加点准则建立代理模型。采用该设计方法,以典型民机机身下部结构设计问题为算例,对客舱地板支撑结构、货舱地板和泡沫构件形状参数进行优化。结果表明,相对原始设计客舱地板的加速度峰值降低约18.3%,次高加速度峰值也得到有效降低,改善了机身结构的耐撞性;Kriging模型预测响应与有限元分析结果误差小于1%,说明了设计方法的有效性。     

An output feedback controller for a synchronous generator

A novel approach using eigenstructure assignment is developed for the design of excitation controllers for synchronous generators. The computation procedure for the method is easy to apply, and an exact solution can be obtained without iteration. Controllers designed by the proposed approach can be easily implemented by means of proportional-integral (PI) controllers. Practical considerations in reaching an optimum selection of closed-loop eigenvalues are addressed. Time-domain simulation results are presented to verify the effectiveness of the design method     

Radar Waveform Selection-A Simplified Approach

Radar measurement and resolution performance, as well as target detection in clutter, depend largely on the transmitted waveform. This explains the sizable effort that has gone into studies of radar waveforms, including attempts at the synthesis of optimum waveforms. This paper shows that, despite the unlimited variety of radar signals, waveform selection is a straightforward process. There are only four classes of waveforms, each with distinct resolution properties. When the target environment is analyzed for a particular application, it is rather evident which of these classes will fit the situation best. Choice of the specific waveform within the selected class then is merely a matter of practical implementation. Although the facts used in developing the unified theory of this paper are not new, it is demonstrated that these facts can be combined into an extremely simple theory of waveform design. Much of today's work is guided by past approaches to a particular problem, and when a design is completed there may be a question as to how close to the optimum it is. The theory presented here permits a systematic approach to waveform selection, with the important benefit that the designer knows exactly where and how much he may have deviated from the best design, and why this was done.     

基于直觉模糊优选动态规划的武器协同运用

将武器运用问题看作一个多阶段多指标的系统,对空战协同武器运用问题进行了分析研究.当作战指标值不能精确给出时,将直觉模糊优选理论与动态规划技术相结合,提出了一种基于直觉模糊优选动态规划.将各作战方案的指标值转化为一个模糊决策矩阵,得出各个作战方案的直觉模糊评价值.通过实例进行了仿真分析,结果表明,所提出的方法可以得到各个阶段的最优决策     

Improved target classification using optimum polarimetric SARsignatures

We present a new method for automatic target/object classification by using the optimum polarimetric radar signatures of the targets/objects of interest. The state-of-the-art in radar target recognition is based mostly either on the use of single polarimetric pairs or on the four preset pairs of orthogonal polarimetric signatures. Due to these limitations, polarimetric radar processing has been fruitful only in the area of noise suppression and target detection. The use of target separability criteria for the optimal selection of radar signal state of polarizations is addressed here. The polarization scattering matrix is used for the derivation of target signatures at arbitrary transmit and receive polarization states (arbitrary polarization inclination angles and ellipticity angles). Then, an optimization criterion that minimizes the within-class distance and maximizes the between-class metrics is used for the derivation of optimum sets of polarimetric states. The results of the application of this approach on real synthetic aperture radar (SAR) data of military vehicles are obtained. The results show that noticeable improvements in target separability and consequently target classification can be achieved by the use of the optimum over nonoptimum signatures     

吸气式空气涡轮冲压发动机的过渡态性能

为计算吸气式空气涡轮冲压(air-turbo-ramjet,ATR)发动机过渡态性能,建立了ATR发动机过渡态模型.通过与传统涡喷发动机供油原则对比得到了ATR发动机供油应遵循的规律,计算得到了给定供油规律下的ATR发动机加减速性能.结果显示ATR发动机在供油规律选择上更加灵活,并能很好地满足喘振裕度的要求.根据ATR发动机自身特点,在补足低转速特性后,本模型可直接模拟ATR发动机起动过程.      

基于二级优化的低RCS外形设计方法

针对飞行器外形隐身优化问题,提出了一种流程简单,可同时优化外形轮廓和剖面形状的二级优化方法。这种方法将优化流程分为外形轮廓级和剖面形状级两个层次:外形轮廓级优化任务是将轮廓形状参数传递给剖面形状级,并对外形轮廓进行优化;剖面形状级优化任务是对剖面形状进行优化,并将目标函数值返回外形轮廓级。二级优化的最终结果可获得最优的轮廓形状和剖面形状。以一个具有低RCS特征的飞行器机身为算例,验证了这种二级优化方法的可行性和有效性。     

面向机翼气动外形优化的二级优化方法

针对飞机气动外形优化问题,提出了一种流程简单,可同时优化总体外形和剖面形状的二级优化方法.这种方法将优化流程分为总体外形级和剖面形状级两个层次:总体外形级优化任务是将外形参数传递给剖面形状级,并对总体外形进行优化;剖面形状级优化任务是对剖面形状进行优化,并将目标函数和约束值返回总体外形级.二级优化的最终结果可获得最优的总体外形和剖面形状.文章以一个通用航空飞机的机翼为算例,验证了这种二级优化方法的可行性和有效性.     

Simplified Optimum Modulation Indices

The design of a narrowband, phase-modulated, multisubcarrier, phase-coherent, space-communication system requires that the subcarrier modulation indices be kept within close tolerance limits. This need arises since the modulation indices directly affect the division of power among the carrier and subcarriers. If the system is not designed in an optimum manner to handle large tolerance variation, the system performance may degrade sharply in an adverse environment. A universal graphical technique?modulation loss contours?is developed as a design tool for the ?optimum? selection of modulation indices. The technique is novel in that it yields solutions directly from the universal curves and does not require the drawing of additional curves. Two criteria of optimization are considered, simultaneous thresholding and minimal sensitivity. The minimally sensitive case is considered as weighted simultaneous thresholding and is solved by the aid of a graphical algorithm. The technique is applicable to k subcarriers (sinusoidal and/or square wave), considering three subcarriers at a time-two subcarriers as direct variables and the third as a parameter?all other subcarriers remaining constant. Previous techniques required trial and error methods, drawing of curves, or computerized search techniques to arrive at the proper modulation indices and maximum tolerance bands. This method allows a quick solution to the tolerance problem and optimum selection of modulation indices, facilitating the design and/or analysis of narrowband PM systems.