手持式激光光色性能测量系统实现及误差分析

鉴于激光波长相对固定的特性,采用一种新的测量激光光色性能测量方法,设计出基于单片机的手持式高精度激光光色性能测量系统。该系统可实现不同波长激光光色性能测量,通过系统初始化时波长输入来提取相应光谱三刺激值,而后进行参数计算。对测量系统进行了实验误差分析,由系统验证结果及误差分析表明,该系统可实现低成本制作,所述测量原理能完成对色空间坐标、光照度、色温等光色性能参数的高精度测量。     

Improving hydrogen storage performance of Li–Mg–N–H system by adding niobium hydride

Hydrogen storage properties of 2LiNH2 – MgH2 –xNbH(x = 0 and 0.05) composites and the catalysis of NbH on hydrogen sorption reaction of the Li–Mg– N–H system were investigated. Hydrogen sorption properties of 2LiNH2 –MgH2 system are effectively improved by adding NbH. Temperature programmed desorption results show the addition of NbH reduces the dehydriding onset temperature of 2LiNH2 –MgH2 system by 21 K. Approximate 3.62 wt% hydrogen in 2LiNH2 –MgH2 – 0.05NbH composite is released following a 500 min at 433 K, whereas the amount of hydrogen desorption is only *3.16 wt% for the pristine system under the same condition. The sample with NbH exhibits higher dehydriding rate compared with the pristine one. Moreover, hydrogen absorption rate increases by adding NbH into the 2LiNH2 – MgH2 system. Hydrogen absorption capacity of the samples with NbH is 3.23 wt% within 400 min, which is higher than that of pristine sample. Fine NbH particles homogeneously distribute in the 2LiNH2 –MgH2 –0.05NbH composite, and catalyze the hydrogen sorption reaction rather than reacts as a reactant into new compound.     

Minimum variance hedging with bivariate regime-switching model for WTI crude oil

This paper proposes a four-regime bivariate Markov regime-switching model to estimate the daily time-varying minimum variance hedge ratios for West Texas Intermediate (WTI) crude oil, and evaluates its in- and out-of-sample hedging performances with two-regime model, CC-GARCH, TVC-GARCH, and OLS models. Empirical results reveal that the four-regime Markov switching model outperforms the other models for both in- and out-of-sample hedging performance. Based on Hansen’s SPA test (2005), the four-regime model significantly outperforms the other models for only in-sample hedging.     

The improved electrocatalytic activity of palladium/graphene nanosheets towards ethanol oxidation by tin oxide

Tin oxide (SnO₂)/graphene nanosheets (GNS) composite was prepared by a simple chemical-solution method as the catalyst support for direct ethanol fuel cells. Then the SnO₂-GNS composites supporting Pd (Pd/SnO₂-GNS) catalysts were synthesized by a microwave-assisted reduction process. The Pd/SnO₂-GNS catalysts were characterized by using X-ray diffraction, transmission electron microscopy and energy-dispersive spectroscopy techniques. The electrocatalytic performances of Pd/SnO₂-GNS catalysts for ethanol oxidation were studied by cyclic voltammetric and chronoamperometric measurements. It was found that compared with Pd/GNS, the Pd/SnO₂-GNS catalyst showed superior electrocatalytic activity for ethanol oxidation when the mass ratio of SnCl₂·2H₂O precursor salt to graphite oxide was about 1:2.     

稀土贮氢电池的发展现状及对策

本文综述了我国稀土贮氢电池的主要发展状况。1990年前我国已能生产作为电池(Ni/MH)负极材料的稀土贮氢合金，1990年初期就开始制造电池（Ni／MH)，且在1995年后逐步走向工业化生产水平。目前我国的这种电池的原料供给能力、电池的生产技术及装备、检测手段、电池的综合技术性能等方面都处于世界先进水平。     

Optimisation of opaque components of the building envelope. Energy,economic and environmental issues

The European Directive 2002/91 will enforce the Member State to promote the implementation of new measures, instruments and calculation methodology to improve the buildings energy performances. The thermal performance and quality of the Italian residential buildings is generally poor, depending on the age of the building stock and the lack of application of the existing energy regulations. This study aims at demonstrating the global benefits of good insulated building envelopes. Energy benefits are easy to understand, meanwhile the economic issues are critical, since the final users see them as an additional useless extra cost for the dwelling at the purchase phase, with small attention to the future managing costs. The study demonstrates that significant economic advantages come out from high–performance building envelope. The study also shows that environmental extra loads due to a bigger use of the insulating material is paid back in few years, with consistent social benefits, if the life cycle of the building is taken into account.     

微粒电解二氧化锰电性能及应用

通过化学分析、物理检验及干电池放电等方法研究了微粒电解二氧化锰（ＣＥＭＤ）特性，并讨论了ＣＥＭＤ的电性能及与低活性ＮＭＤ搭配使用效果     

A study of assessors'' performance using graphical methods

The performance of a sensory panel is studied through analysis of variance and in particular the assessors × products interaction. A graphic can illustrate the partitioning of the interaction by a sum of distances between the assessors. The decomposition of the sum of the product effect plus the interaction allows a vector representation of the assessors. These vectors are classified with an original method in order to point out homogeneous sub-panels. The new classification allows aggregation of groups only when all the correlations between assessors are greater than a threshold.     

用熵权法和主成份投影法优选PDC钻头

针对深井、超深井深部井段钻井提速难题,可通过优选PDC钻头提高钻进速度、降低钻井成本。为了全面、客观地评价钻头性能的优劣,文在选取纯钻时间、机械钻速、进尺等钻头性能评价指标的基础上,采用熵权法对各评价指标赋权,应用主成份投影法对某油田PDC钻头性能进行评价并优选PDC钻头。采用优选出的PDC钻头,试验井平均机械钻速比邻井同组地层提高了15%,表明钻头选型方法合理,可用来优选和评价PDC钻头