TLE orbit determination using simplex method

Two-Line Element(TLE)datasets are the only orbital data source of Earth-orbiting space objects for many civil users for their research and applications.The datasets have uneven qualities that may affect the reliability of the propagated positions of space objects using a single TLE.The least squares approach to use multiple TLEs also suffers from the poor quality of some TLEs,and reliable error information cannot be available.This paper proposes a simplex algorithm to estimate an optimal TLE from multiple TLEs and obtain the uncertainty of each element.It is a derivative-free technique that can deal with various orbit types.Experiments have demonstrated that using the TLE estimated from the simplex method is more reliable,stable,and effective than those from the batch least squares method.As an application example,the optimal TLE and its uncertainty are used for predicting the fallen area,keeping the actual fallen site in the prediction areas.

Cs_(4)EuI_(6)∶Sm近红外闪烁晶体的生长及发光性能研究

随着长波敏感硅基光电探测器的发展,近红外闪烁晶体逐渐成为研究热点,其中Sm^(2+)掺杂的Eu^(2+)基卤化物晶体表现出优异的近红外发光性能。本文利用布里奇曼法成功制备了尺寸达到厘米级别的Cs_(4)EuI_(6)∶Sm近红外闪烁晶体,通过XRD、XPS和ICP-OES等手段研究了晶体的组分和结构。结果表明,Sm^(2+)成功掺入Cs_(4)EuI_(6)基质,且对基质的晶体结构无明显影响。在紫外和X射线的激发下,晶体主要呈现两个发光中心(Eu^(2+)和Sm^(2+)),发光峰位于450和840 nm左右,分别对应于Eu^(2+)和Sm^(2+)的5d→4f的跃迁发光,紫外激发下的Eu^(2+)和Sm^(2+)的荧光衰减寿命均处于微秒级别。结果表明,随着Sm^(2+)掺杂浓度的增加,发光波长由蓝光逐渐变为近红外光。同时系统研究了不同Sm^(2+)浓度掺杂对晶体发光性能、Eu^(2+)-Sm^(2+)能量传递及荧光寿命的影响,实验结果表明,改变Sm^(2+)掺杂浓度可以调控晶体的发光性能。

KY(CO_(3))_(2):Sm^(3+)新型红光荧光粉的制备及其发光性能研究

为解决白光LED中因蓝光芯片激发黄色荧光粉而导致显色指数较低问题,采用水热法制备一种新型红光荧光粉KY(CO_(3))_(2):Sm^(3+)。通过X射线粉末衍射、光致发光光谱、色度坐标及荧光寿命等表征手段研究样品的物相结构及其发光性能。结果表明:掺入Sm^(3+)后,KY(CO_(3))_(2)的晶体结构并没有发生改变。随着Sm^(3+)掺杂量的增加,荧光粉的发光强度先增强后减弱,最佳掺杂浓度为10%。Dexter理论分析表明,Sm^(3+)的浓度猝灭归因于电偶极-电偶极相互作用机制。以596 nm作为监测波长,KY(CO_(3))_(2):Sm^(3+)荧光粉激发峰主要包含402 nm (6H_(5/2)→4F_(7/2))和474 nm (6H_(5/2)→4I_(13/2)) 2波长,表明该荧光粉可以被商用紫外LED芯片和蓝光LED芯片有效激发。改变Sm^(3+)掺杂比例,荧光粉色度坐标值基本保持不变,均位于标准红光区,因此KY(CO_(3))_(2):Sm^(3+)红光荧光粉有望作为白光LED用红光荧光粉。

Effect of Dopant Concentration on Luminescence Properties of KCaPO4:Sm

KCaPO4 doped with different concentrations of Sm was synthesised by a high-temperature solid-state method, and the crystal structure, morphology, TL and OSL properties of Sm-doped KCaPO4 were systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermoluminescence (TL), and optically stimulated luminescence (OSL) techniques. The results show that 0.3 mol% Sm-doped KCaPO4 annealed at 1073 K for 1 h has the highest TL intensity, and thus is expected to be a candidate material for thermoluminescence dosimetry applications.

碱金属掺杂对高温固相法制备的CaMoO_(4):Sm^(3+)荧光粉发光性质的影响

在无机发光材料领域里,值得注意的是具有稳定化学及物理性质的优良材料钼酸钙。本次研究使用高温固相法制备一系列单一基质Ca MoO_(4)掺杂Sm^(3+)的白光荧光粉,并使用XRD测试其物相结构,用激发和发射光谱测试发光性能。最终研究发现钼酸钙(CaMoO_(4))中Sm^(3+)掺杂浓度为0.020时,荧光粉发光性能最强。当进一步掺杂碱金属作电荷补偿剂时,CaMoO_(4):0.020Sm^(3+)的发光强度最优异,其中掺杂K^(+)的荧光粉样品具有最大的发光强度,表明这种荧光粉在发光二极管照明方面具有深远而广阔的发展前景。

Simplexmethod建模研讨

目的 Linear Programming的simplexmethod建模求最优解。方法应用simplexmethod.结果建立了LinearProgramming的数学模型并用simplexmethod求得了最优解.结论因为单纯形表反映了Linear Programming的所有信息,故用simplexmethod可简便地求得最优解.simplexmethod的基本思路是:先将Linear Programming用sim-plexmethod划为标准型,根据问题的标准型,进行初等行变换,将主元素列除主元素化为1外其余的元素均化为0,当基变量值全为非负时,问题就得到了最优解.

Global convergent algorithm for the bilevel linear fractional-linear programming based on modified convex simplex method

A global convergent algorithm is proposed to solve bilevel linear fractional-linear programming, which is a special class of bilevel programming. In our algorithm, replacing the lower level problem by its dual gap equaling to zero, the bilevel linear fractional-linear programming is transformed into a traditional sin- gle level programming problem, which can be transformed into a series of linear fractional programming problem. Thus, the modi- fied convex simplex method is used to solve the infinite linear fractional programming to obtain the global convergent solution of the original bilevel linear fractional-linear programming. Finally, an example demonstrates the feasibility of the proposed algorithm.

Partial Pricing Rule Simplex Method with Deficient Basis

A new partial pricing column rule is proposed to the basis-deficiency-allowing simplex method developed by Pan.Computational results obtained with a set of small problems and a set of standard NETLIB problems show its promise of success.

PID Parameters for Tuning and Optimization of a Turbine EngineBased on the Simplex Search Method

A PID parameters tuning and optimization method for a turbine engine based on the simplex search method was proposed. Taking time delay of combustion and actuator into account, a simulation model of a PID control system for a turbine engine was developed. A performance index based on the integral of absolute error （IAE） was given as an objective function of optimization. In order to avoid the sensitivity that resulted from the initial values of the simplex search method, the traditional Ziegler-Nichols method was used to tune PID parameters to obtain the initial values at first, then the simplex search method was applied to optimize PID parameters for the turbine engine. Simulation results indicate that the simplex search method is a reasonable and effective method for PID controller parameters tuning and optimization.

Estimation of mass transfer coefficient in ozone absorption by linear least square fitting and Simplex search methods

For physical ozone absorption without reaction,two parametric estimation methods,i.e.the common linear least square fitting and non-linear Simplex search methods,were applied,respectively,to determine the ozone mass transfer coefficient during absorption and both methods give almost the same mass transfer coefficient.While for chemical absorption with ozone decomposition reaction,the common linear least square fitting method is not applicable for the evaluation of ozone mass transfer coefficient due to the difficulty of model linearization for describing ozone concentration dissolved in water.The nonlinear Simplex method obtains the mass transfer coefficient by minimizing the sum of the differences between the simulated and experimental ozone concentration during the whole absorption process,without the limitation of linear relationship between the dissolved ozone concentration and absorption time during the initial stage of absorption.Comparison of the ozone concentration profiles between the simulation and experimental data demonstrates that Simplex method may determine ozone mass transfer coefficient during absorption in an accurate and high efficiency way with wide applicability.

Numerical Optimization of Sand Casting Parameters Using the Dantzig’s Simplex Method

This study adopts the Dantzig’s Simplex method to investigate optimization of sand casting parameters for optimum service performance. Some process variables and mechanical properties were adapted into the Simplex method. Aluminium alloy samples were cast, machined and subjected to a series of mechanical tests. From the body of data collected, linear functions and constraint equations were formulated and employed in the Dantzig’s Simplex method for optimization of process parameters. The results showed that the Simplex method can be adapted for studying performance opti- mization of castings.

Application of Simplex Method in the Radiotherapy Treatment

This work presents an application of the Simplex Method for solving an optimal planning problem for cancer treatment by radiotherapy. Linear Programming can aid the optimal planning for radiation therapy, where the concern is to apply a high enough radiation in the tumor while saving significantly healthy regions or critical organs.

Minimizing Complementary Pivots in a Simplex-Based Solution Method for a Quadratic Programming Problem

The paper presents an approach for avoiding and minimizing the complementary pivots in a simplex based solution method for a quadratic programming problem. The linearization of the problem is slightly changed so that the simplex or interior point methods can solve with full speed. This is a big advantage as a complementary pivot algorithm will take roughly eight times as longer time to solve a quadratic program than the full speed simplex-method solving a linear problem of the same size. The strategy of the approach is in the assumption that the solution of the quadratic programming problem is near the feasible point closest to the stationary point assuming no constraints.

Using the Simplex Method for a Type of Allocation Problems

In this study we discuss the use of the simplex method to solve allocation problems whose flow matrices are doubly stochastic. Although these problems can be solved via a 0 - 1 integer programming method, H. W. Kuhn [1] suggested the use of linear programming in addition to the Hungarian method. Specifically, we use the existence theorem of the solution along with partially total unimodularity and nonnegativeness of the incidence matrix to prove that the simplex method facilitates solving these problems. We also provide insights as to how a partition including a particular unit may be obtained.

Optimal Design of Aperture Illuminations for Microwave Power Transmission with Annular Collection Areas

This work presents an optimal design method of antenna aperture illumination for microwave power transmission with an annular collection area.The objective is to maximize the ratio of the power radiated on the annular collection area to the total transmitted power.By formulating the aperture amplitude distribution through a summation of a special set of series,the optimal design problem can be reduced to finding the maximum ratio of two real quadratic forms.Based on the theory of matrices,the solution to the formulated optimization problem is to determine the largest characteristic value and its associated characteristic vector.To meet security requirements,the peak radiation levels outside the receiving area are considered to be extra constraints.A hybrid grey wolf optimizer and Nelder–Mead simplex method is developed to deal with this constrained optimization problem.In order to demonstrate the effectiveness of the proposed method,numerical experiments on continuous apertures are conducted;then,discrete arrays of isotropic elements are employed to validate the correctness of the optimized results.Finally,patch arrays are adopted to further verify the validity of the proposed method.

新型橙红色荧光粉Sr_(3)CaNb_(2)O_(9)∶Sm^(3+)的制备及发光性能研究

通过高温固相法制备了一系列Sr_(3)CaNb_(2)O_(9)∶xSm^(3+)(0.04≤x≤0.1)新型橙红色荧光粉。研究了其物相、形貌、发光性能、热稳定性和CIE色度坐标。X射线衍射(XRD)物相分析和Rietveld精修结果表明合成了Sr_(3)CaNb_(2)O_(9)的纯相。在407nm的紫光激发下,Sr_(3)CaNb_(2)O_(9)∶Sm^(3+)在645nm处发红光,可归因于Sm^(3+)的^(4)G_(5/2)→^(6)H_(9/2)跃迁。实验表明Sr_(3)CaNb_(2)O_(9)∶xSm^(3+)的最佳掺杂浓度为x=0.07,根据Dexter理论分析,其浓度猝灭机理为电偶极-电偶极相互作用。Sr_(3)CaNb_(2)O_(9)∶Sm^(3+)在423K下发光强度是室温下的90.3%,表现出良好的热稳定性。Sr_(3)CaNb_(2)O_(9)∶xSm^(3+)的发光色坐标均位于橙红色区域,且具有较高的色纯度。结果表明Sr_(3)CaNb_(2)O_(9)∶Sm^(3+)荧光粉在白光发光二极管(WLED)中具有潜在的应用前景。

基于SM-PSO算法的船舶板架结构多目标优化设计

当前的船舶板架结构多目标优化模型通常设定为单项,优化效果受限,导致屈服强度比增加,为此提出基于单纯形法-粒子群算法(Simplex Method-Particle Swarm Optimization,SM-PSO)的船舶板架结构多目标优化设计。根据优化的需求及标准提取船舶板架结构的振动特征,设计SM-PSO算法下的多阶优化模型,并采用有限元ANSYS处理实现板架优化。

Sm^(3+)离子激活Y_(2)MgTiO_(6)橙红色荧光粉的制备及发光性质研究

采用溶胶-凝胶法合成了一系列橙红色发光的Y_(2-2x)MgTiO_(6)∶2xSm^(3+)(YMT∶2xSm^(3+),0≤x≤0.11)荧光粉。通过粉末X射线衍射仪(XRD)、扫描电子显微镜(SEM)、光致发光激发和发射光谱对样品进行了表征分析。结果表明,所制备的YMT∶Sm^(3+)样品为纯相,无任何杂质;荧光粉颗粒尺寸为2~3μm,分散性较好且无明显团聚。在407 nm的近紫外光激发下,样品的发射光谱在500~700 nm波长范围内存在三个显著的发射峰,分别是603 nm(~4G_(5/2)→~6H_(7/2))和650 nm(~4G_(5/2)→~6H_(9/2))处较强的红光,以及566 nm(~4G_(5/2)→~6H_(5/2))处较弱的绿光。Sm^(3+)离子的最佳掺杂浓度为5 mol%,理论计算出Sm^(3+)离子的临界转移距离为1.619 nm。当Sm^(3+)浓度超过5 mol%时,出现明显的浓度猝灭效应,该效应归因于Sm^(3+)离子之间电四极子-电四极子(q-q)相互作用。YMT∶Sm^(3+)荧光粉的CIE色度坐标位于橙红光区域,是一种具有潜在应用价值的白光LED用红色荧光粉。

LaVO_4:Sm^(3+)荧光粉的水热合成及其荧光性能

以柠檬酸三钠为络合剂,硝酸镧、硝酸钐、偏钒酸铵为主要原料,采用水热法于180℃反应12 h,制备了一系列La_(1-x)VO_4:x Sm^(3+)(x=0,1.0%,1.5%,2.0%,2.5%,3.0%,4.0%)样品。通过X射线粉末衍射、场发射扫描电镜和荧光光谱对样品的结构、形貌以及发光性能进行了表征。结果表明:所合成样品为LaVO_4的四方相和单斜相混合晶体,其形貌为六面体形和纳米颗粒;在311 nm波长激发下,LaVO_4:Sm^(3+)样品的最强发射峰位于602 nm处,对应于Sm^(3+)的~4G_(5/2)→~6H_(7/2)跃迁,且Sm^(3+)最佳掺杂摩尔浓度为2.0%。