共查询到19条相似文献,搜索用时 62 毫秒
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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。 相似文献
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GaN 用衬底材料 LiGaO2 晶体超精密抛光的初步实验 总被引:2,自引:0,他引:2
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。 相似文献
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激光清洗硅片表面Al2O3颗粒的试验和理论分析 总被引:2,自引:5,他引:2
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。 相似文献
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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. 相似文献
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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。 相似文献
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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。 相似文献
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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。 相似文献
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Cr3+:YAB和Cr3-: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。 相似文献
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紫外-真空紫外波段的Al+MgF2膜 总被引:4,自引:2,他引:4
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。 相似文献
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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. 相似文献
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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。 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献