K1±(892) Production in π−N interactions at 200 GeV/c

K^1±(892) production is studied in the reaction π^?N → K_S⁰K_S⁰ + X where X includes up to five observed charged particles. An excess of K^1? over K¹⁺ is observed for Feynman-x > 0.1. The ratio of K¹⁺ to K^1? decreases with x as predicted by QCD counting rules. K_S⁰ and K¹ production are compared to recent D and D¹ data from other experiments.     

铈对混合型贵金属尾气净化催化剂性能的影响

系统地研究了CeO2对负载型混合贯金属催化剂性能的影响，考察了模拟尾气排放条件下铈对催化剂CO氯化性能的影响，并应用XRD、TPD等手段对CeO2在催化剂中的作用机理进行了研究。结果表明，添加助剂后催化剂活性明显提高．铈的添加改变了催化剂的吸附性能．有利于降低催化反应的活化能。     

Asymptotic approximation of kernel-type estimators with its application

Sufficient conditions are given under which a generalized class of kernel-type estimators allows asymptotic approximation on the modulus of continuity. This generalized class includes sample distribution function, kernel-type estimator of density function, and an estimator that may apply to the censored case. In addition, an application is given to asymptotic normality of recursive density estimators of density function at an unknown point.     

Interface characterization and indium content of indium-rich quantum dots in InGaN/GaN multiple quantum wells

We report on the interface characterization of InGaN/GaN multiple quantum wells with indium aggregation grown by metalorganic chemical vapor deposition. The interface related microstructure was analyzed by high-resolution transmission electron microscopy, high-resolution X-ray diffraction and high angle annular dark field. Luminescence measurements were carried out by micro-photoluminescence measurement. In addition, quantitative determination of the indium concentration inside the ultra-small dots was attempted. We demonstrate that the quantum dots are coherent and the interfaces remain sharp. The In content inside ∼2 nm InGaN dots is about 65% determined by spectrum imaging in energy-filtered transmission electron microscopy combined with multiple linear least squares fitting, which is slighter higher than the value obtained either from HRTEM or theoretical calculations. This discrepancy is briefly discussed but demands further studies for complete understanding.     

固定化肌红蛋白的氧化还原反应和类酶活性

用魔芋多糖（KGM）将肌红蛋白（Mb）固定在玻碳电极（GC）表面，制备了Mb—KGM膜修饰电极．结果表明，包埋在KGM中的Mb可以与电极发生直接电子传递．Mb—KGM膜修饰电极在水／有机混合溶液中，表现出可逆的直接电子传递过程．式电势（E^0=-0．434V）表明该电化学响应是MbFe（Ⅲ）／Fe（Ⅱ）电对的氧化还原．在一定范围内，溶液pH值增加，Mb氧化还原式电势负移，且呈线性关系，说明Mb的电子传递过程伴随有质子的转移．在乙醇等亲水性有机溶剂与水的混合溶液中，Mb表现出类似细胞色素P450的催化活性，能快速地催化氯代乙烷（六氯乙烷、五氯乙烷和四氯乙烷等）脱氯．Mb—KGM膜修饰电极具有较好的稳定性和重现性，可用于这些物质的定量检测．     

A novel method to measure the cell gap and pretilt angle of a reflective liquid crystal display

A powerful method for the phase retardation measurement of a reflective liquid crystal cell is presented. The proposed method is based on the heterodyne interferometer theory for probing cell parameters. Due to common-path optical arrangement, a fast measurement with high accuracy and sensitivity was possible. Both theoretical analysis and experimental procedures are presented. The experimental results agree well with that obtained theoretically.     

Optimum Burn-in Time for a Bathtub Shaped Failure Distribution

An important problem in reliability is to define and estimate the optimal burn-in time. For bathtub shaped failure-rate lifetime distributions, the optimal burn-in time is frequently defined as the point where the corresponding mean residual life function achieves its maximum. For this point, we construct an empirical estimator and develop the corresponding statistical inferential theory. Theoretical results are accompanied with simulation studies and applications to real data. Furthermore, we develop a statistical inferential theory for the difference between the minimum point of the corresponding failure rate function and the aforementioned maximum point of the mean residual life function. The difference measures the length of the time interval after the optimal burn-in time during which the failure rate function continues to decrease and thus the burn-in process can be stopped.      

Distributed temperature measurement using a Fabry-Perot effect based chirped fiber Bragg grating

A temperature distribution sensing system based on the reflection spectrum of a 70 mm apodized chirped fiber Bragg grating has been demonstrated. Reflection variations created by the Fabry-Perot effect due to the intra-grating wavelength shift are presented. By fitting a parametric transfer matrix model of the grating response to measured spectra, the temperature change, position and width of a localized temperature change are obtained. This system is particularly attractive of its simplicity, high spatial resolution and ability in measuring a non-monotonic distribution. Experiments to measure two localized heating regions along the grating indicate that the technique is promising for measuring more complex temperature profiles.     

Properties of vertex cover obstructions

We study properties of the sets of minimal forbidden minors for the families of graphs having a vertex cover of size at most k. We denote this set by O(k-VERTEX COVER) and call it the set of obstructions. Our main result is to give a tight vertex bound of O(k-VERTEX COVER), and then confirm a conjecture made by Liu Xiong that there is a unique connected obstruction with maximum number of vertices for k-VERTEX COVER and this graph is C_2k+1. We also find two iterative methods to generate graphs in O((k+1)-VERTEX COVER) from any graph in O(k-VERTEX COVER).