单价银离子在 CaO-P2O5 系统玻璃中的发光特性

在弱还原气氛下制备了单价银离子(Ag⁺)掺杂的CaO-P₂O₅系统玻璃,测试了其在室温下的吸收光谱、激发光谱和发射光谱。Ag⁺-CaO-P₂O₅玻璃的吸收光谱表明两个吸收峰。高能峰位于220nm波长,由4d¹⁰→4d⁹5P¹跃迁引起,低能峰中心位于240nm波长,归因于4d¹⁰→4d⁹5s¹跃迁,该吸收与其发射特性有关。紫外波段的宽带吸收产生了可见波段强烈的荧光发射,发光峰位于440nm波长,半宽度为130nm.研究了掺质浓度与发光特性的关系,随着掺质浓度的增加(0.05～0.25mol%),发光峰向较长波段移动。在Ag₂O含量为0.5mol%时,出现了浓度猝灭现象。为了比较起见,同时还研制了Cu⁺-CaO-P₂O₅及Cu⁺-Ag⁺-CaO-P₂O₅玻璃。     

GaN 用衬底材料 LiGaO2 晶体超精密抛光的初步实验

主要介绍了作为发光半导体GaN衬底材料的LiGaO₂单晶超精密抛光方法及初步结果。利用聚氨酯抛光盘配合SiO₂悬浮液,采用机械化学抛光方法,已加工出表面粗糙度优于0.1mm,的超光滑表面。     

Al2O3单晶镜片精密磨削加工工艺研究

分析硬脆性材料磨削的特点与难点,介绍目前精密磨削硬脆性材料的三种常用加工技术。通过研究实现硬脆性材料精密磨削条件,结合Al2O3精密磨削试验,提出大尺寸Al2O3单晶镜片精密磨削的加工工艺参数和方法。     

激光清洗硅片表面Al2O3颗粒的试验和理论分析

以KrF准分子激光器为激光源,对目前工业上常用的硅片研磨抛光液的主要成分Al₂O₃颗粒进行激光清洗的试验和理论分析。建立一维热传导模型,利用有限元分析软件MSC.MarC模拟硅片表面的温度随激光作用时间和能量密度的分布。通过理论计算,量化了颗粒所受到的清洗力以及其与硅片表面之间的粘附力,理论预测出1 μm Al₂O₃颗粒的激光清洗阈值为60 mJ/cm²。在理论分析的指导下,利用248 nm、30 ns的KrF准分子激光进行单因素试验,研究激光能量密度、脉冲个数、激光束入射角度对激光干法清洗效率的影响,并且实验验证了清洗模型以及场增强效应对激光清洗结果的影响。     

HfO2薄膜的离子束刻蚀特性研究

实验研究了HfO₂薄膜特性以及掩模材料AZ1350以Ar为工作气体下的离子束的刻蚀特性.给出了离子能量、离子束流密度和离子束入射角等因素与刻蚀速率的关系曲线,用最小二乘法拟合了上述因素与刻蚀斜率的函数关系方程;分析了光刻胶和基片在刻蚀过程中随刻蚀深度的变化对图形转移精度的影响,用AFM的Tapping模式测量了刻蚀前后HfO₂薄膜表面质量的变化.结果表明刻蚀速率与离子能量的平方根,及速流密度成正比,并随离子束入射角变化而变化;与刻蚀前相比,刻蚀工艺降低了因HfO₂薄膜刻蚀深度的增加引起图形转移精度下降,因此提高刻蚀选择比是获得高分辨率图形的前提.研究结果已应用到了在HfO₂/SiO₂多层膜衍射光栅的制作中.     

α-Al2O3/石墨/双马来酰亚胺自润滑复合材料的研究

采用浇铸成型法制备了α-Al2O3/石墨/双马来酰亚胺自润滑复合材料,考察了α-Al2O3的含量和粒径对复合材料摩擦学性能的影响,用扫描电镜对磨损形貌和磨屑进行了分析,并对其磨损机制进行了探讨.结果表明α-Al2O3颗粒大小对摩擦系数、磨损量以及磨损机制有显著影响,含1500目α-Al2O3复合材料的摩擦学性能比含1200目α-Al2O3复合材料的要好得多.     

快速轴流型与密封型CO2激光器超脉冲特性研究

快速轴流型CO₂激光器和密封型CO₂激光器超脉冲运转时,能够获得前沿迅速上升、脉宽窄、峰值功率高的激光脉冲输出,在激光加工和激光医疗等领域有重要应用价值。本文从理论和实验两个方面对快速轴流型与密封型CO₂激光器超脉冲特性进行了研究,设计并研制了适合CO₂激光器超脉冲运转的控制电源,在国内首次实现了快速轴流型与密封型CO₂激光器的超脉冲运转。     

钨镍共掺杂V2O5薄膜的光电特性研究

利用溶胶–凝胶旋涂法和后退火工艺在FTO导电玻璃上制备了钨镍共掺杂V₂O₅薄膜,研究了薄膜在不同温度和不同偏压下的光电特性和相变特性。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM） 和X射线光电子能谱仪（XPS） 测试了钨镍共掺杂V₂O₅薄膜的晶体结构、表面形貌和组分,分析了不同钨镍共掺杂浓度对V₂O₅薄膜相变光电特性的影响。结果表明,当钨和镍的掺杂质量分数分别为3 %和1.5 %时,钨镍共掺杂的V₂O₅薄膜的相变温度为218.5 ℃,在可见光范围内有较高的透过率,在近红外1310 nm波长处的光学透过率达48.83%,与未掺杂V₂O₅薄膜的光学透过率相比提高了10.29%,薄膜电阻降低了30.53%,热致回线宽度收窄为15 ℃,说明钨镍共掺杂的V₂O₅薄膜具有良好的可逆相变光电特性,有望在新型光电器件领域得到较好的应用。     

锡添加量对铸态Mg-3Al-0.5SiO2合金显微组织和力学性能的影响

以纯镁锭、纯铝锭、纯锡锭、纳米SiO₂粉末为原料熔炼铸造Mg-3Al-0.5SiO₂-xSn(x=0,1,3,5,7,10,质量分数/%)合金,研究了锡添加量对合金显微组织和力学性能的影响。结果表明：随着锡添加量的增加,粗大的Mg₂Si初生相逐渐转变为块状或针状相,Mg₂Sn相含量增加,当锡质量分数为5%时,Mg₂Sn相分布最均匀,尺寸最小;合金的强度和断后伸长率均随着锡添加量的增加呈先升高后降低的趋势,断裂方式先由脆性断裂向韧性断裂转变,再向脆性断裂转变;当锡质量分数为5%时,合金具有最佳的室温拉伸性能,其抗拉强度、屈服强度、断后伸长率分别为145.6 MPa, 98.7 MPa, 7.12%,断裂方式为韧性断裂。     

LCD工艺中使用的碱性溶液对SiO2膜层的刻蚀作用

钠钙玻璃基片上的SiO₂膜层在很大程度上决定了液晶显示器件(LCD)的化学稳定性及使用寿命。本文以射频溅射法制备的SiO₂膜层为样品,结合LCD工艺特点,初步研究分析了其工艺流程中所使用的不同碱性溶液对SiO₂膜层不同的刻蚀作用。本文的结论有利于在LCD工艺中更好地保护SiO₂膜层。     

可用于自倍频激光器的Cr3+:YAB和Cr3+:YGAB晶体光学特性的研究

Cr³⁺:YAB和Cr^3-:YGAB晶体具有较宽的荧光光谱,从红光到近红外光。Cr³⁺:YAB晶体在744nm到852.5nm之间被测到光学增益。最大单程增益为1.9,对应波长为820nm.Cr³⁺:YAB晶体的二次谐波产生(37nm)的转换效率是LBO晶体的1.5倍。     

基于桨叶模态修型的直升机减振优化

基于Hamilton原理推导了模态修型减振优化的有限元动力学模型,通过修改桨叶的剖面刚度和线密度来改变结构的动力学模态。以最小振动载荷为目标函数,以桨叶剖面刚度及质量为设计变量,以桨叶的频率、自转惯量、质量及模态修型参数等为约束条件,进行了减振优化。算例表明:在约束条件都满足的情况下,优化后,3/转的桨根剪力减小了55.4%,4/转的桨根剪力减小了66.5%,5/转的桨根剪力减小了53.4%,优化效果明显。     

紫外-真空紫外波段的Al+MgF2膜

Al+MgF₂膜是真空紫外波段常用的一种反射膜。根据薄膜光学的电磁场理论计算了正入射条件下Al+MgF₂膜在真空紫外波段的反射率随氟化镁膜厚度的变化规律。研究了Al+MgF₂膜的制备工艺,利用Seya-Namioka紫外-真空紫外反射率计测得Al+MgF₂膜的反射率在150nm～340nm的波段上高于80%。Al+MgF₂膜制备一年后,其真空紫外波段的反射率未有明显变化。     

Improvement of KFM performance by intermittent bias application method and by sampling detection of cantilever deflection

We have proposed an intermittent bias application method as well as a sampling detection method of cantilever deflection in Kelvin probe force microscopy (KFM) to improve its performances for surface potential measurements. In the former method, spiky biases, instead of the bias in a sinusoidal waveform normally used in KFM, are intermittently applied to generate electrostatic force at exact moments when the tip approaches the closest position to a sample surface. The latter one, on the other hand, realizes very sensitive detection of the electrostatic force, which is preferable in KFM. Both the dependence of the electrostatic force on the dc offset bias and the observed potential images clearly indicate that these two methods are very effective to improve the KFM performance.     

基于状态空间自回归最小二乘的车辆质心侧偏角非线性估计

基于动力学模型对车辆质心侧偏角进行了估计。为使轮胎模型能够适应不同附着系数的路面,将动态参数引入“魔术公式”轮胎侧偏力模型。应用状态空间形式的自回归最小二乘算法（RLS）设计了车辆质心侧偏角估计器。通过车辆在高附着系数路面的蛇形试验和变附着系数路面的双移线试验对估计方法进行了验证,结果表明,即使车辆出现大侧偏情况使轮胎进入到侧偏角-侧偏力特性曲线的非线性区域,提出的估计方法也能够实现对质心侧偏角的估计。将该估计方法与扩展卡尔曼滤波估计在精度、计算效率和使用条件等方面进行了比较,进一步表明所提出方法具有良好性能。     

Computation of a turbulent natural convection in a rectangular cavity with the low-reynolds-number differential stress and flux model

A numerical study of a natural convection in a rectangular cavity with the low-Reynoldsnumber differential stress and flux model is presented. The primary emphasis of the study is placed on the investigation of the accuracy and numerical stability of the low-Reynolds-number differential stress and flux model for a natural convection problem. The turbulence model considered in the study is that developed by Peeters and Henkes (1992) and further refined by Dol and Hanjalic (2001), and this model is applied to the prediction of a natural convection in a rectangular cavity together with the two-layer model, the shear stress transport model and the time-scale bound model, all with an algebraic heat flux model. The computed results are compared with the experimental data commonly used for the validation of the turbulence models. It is shown that the low-Reynolds-number differential stress and flux model predicts well the mean velocity and temperature, the vertical velocity fluctuation, the Reynolds shear stress, the horizontal turbulent heat flux, the local Nusselt number and the wall shear stress, but slightly under-predicts the vertical turbulent heat flux. The performance of the model is comparable to that of the low-Reynolds-number differential stress and flux model except for the over-prediction of the horizontal turbulent heat flux. The two-layer model predicts poorly the mean vertical velocity component and under-predicts the wall shear stress and the local Nusselt number. The shear stress transport model predicts well the mean velocity, but the general performance of the shear stress transport model is nearly the same as that of the two-layer model, under-predicting the local Nusselt number and the turbulent quantities.     

decentralized observation and control of nonlinear interconnected systems

In this paper, we investigate the problem of H_∞ decentralized tracking control design with a decentralized observer for interconnected nonlinear systems which are characterized by the interconnection of N subsystems. Each subsystem is modeled by a linear constant part perturbed by an additive nonlinearity which is illustrated by the interconnection terms.The proposed feedback control scheme is developed to ensure the asymptotic stability of the augmented system, to reconstruct the non-measurable state variables of each subsystem, to maximize the nonlinearity domain, and to improve the performance of the model reference tracking control by using the H_∞ criterion despite the external disturbances.The proposed control approach is formulated in a minimization problem and derived in terms of linear matrix inequalities (LMIs) whose resolution yields the decentralized control and observation gain matrices.The effectiveness of the proposed control scheme is demonstrated through numerical simulations on a power system with three interconnected machines.     

Recursive fuzzy c-means clustering for recursive fuzzy identification of time-varying processes

In this paper we propose a new approach to on-line Takagi-Sugeno fuzzy model identification. It combines a recursive fuzzy c-means algorithm and recursive least squares. First the method is derived and than it is tested and compared on a benchmark problem of the Mackey-Glass time series with other established on-line identification methods. We showed that the developed algorithm gives a comparable degree of accuracy to other algorithms. The proposed algorithm can be used in a number of fields, including adaptive nonlinear control, model predictive control, fault detection, diagnostics and robotics. An example of identification based on a real data of the waste-water treatment process is also presented.     

Mathematical models of the simplest fuzzy PI/PD controllers with skewed input and output fuzzy sets

This paper unveils mathematical models for fuzzy PI/PD controllers which employ two skewed fuzzy sets for each of the two-input variables and three skewed fuzzy sets for the output variable. The basic constituents of these models are Gamma-type and L-type membership functions for each input, trapezoidal/triangular membership functions for output, intersection/algebraic product triangular norm, maximum/drastic sum triangular conorm, Mamdani minimum/Larsen product/drastic product inference method, and center of sums defuzzification method. The existing simplest fuzzy PI/PD controller structures derived via symmetrical fuzzy sets become special cases of the mathematical models revealed in this paper. Finally, a numerical example along with its simulation results are included to demonstrate the effectiveness of the simplest fuzzy PI controllers.