测量不确定度政策、评定程序及事例

本文介绍了中国实验室国家认可机构对测量不确定度的最新政策与要求，以及评定程序与方法，结合塔机试验，给出了一个不确定度的评定实例。     

改性β沸石上合成1,4-二氧六环的研究

在真空条件下将改性 β沸石用于二甘醇合成 1,4 -二氧六环的反应 ,考察了反应温度、反应时间和催化剂用量对催化剂活性的影响 ,并对该催化剂的稳定性进行了考察。结果表明 ,在最佳反应条件下 ,二甘醇转化率达到 89 6 9% ,1,4 -二氧六环的选择性达到 95 0 1%。     

激光诱导H_2S催化裂解制备H_2的研究

在室温常压静态条件下研究了以Ｖ２Ｏ５／ＴｉＯ２为催化剂，紫外脉冲激光诱导Ｈ２Ｓ催化分解为Ｈ２和Ｓ的反应及其机理。考察了产氢量与激光不同照射条件之间的关系。     

高温超高压处理HDPE的WAXD及FT－IR研究

用ＷＡＸＤ和ＦＴ－ＩＲ对高温超高压处理前后的ＨＤＰＥ进行了研究。发现经５．０ＧＰａ的高压处理或２００℃下４．０ＧＰａ的高压同时处理后的ＨＤＰＥ分子链的化学结构未发生变化。ＨＤＰＥ晶体中（２００）面与（１１０）面衍射峰的峰高比（γ）随着压力的升高而增大，表明ＨＤＰＥ分子链在超高压作用下发生了取向排列，且升高温度更有利于这种取向排列，但当压力增大至５．０ＧＰａ及温度升高至２００℃时，γ反而大幅度下降。     

Evaluation of Soybean Seedcoat Cracking During Drying:PART II. Using MRI

MRI techniques were developed and employed for non-destructive and noninvasive study of seedcoat cracking in low moisture soybean kernels during heated air drying. Proton density image and transient moisture distribution profile of a single soybean kernel can be obtained using MRI. These MRI techniques proved to be particularly useful for the continuous observation of initiation and propagation of seedcoat cracking during the entire period of drying process without interruption.

The proton density images of soybean kernels showed that seedcoat cracking was initiated perpendicular to the long axis of the kernel near the hilum. The transient moisture distribution profiles in soybean kernels during drying indicate that moisture gradient developed during drying was higher in the seedcoat than in the cotyledon. Drying temperature and initial average moisture content were positively correlated with the soyhean seedcoat crackig. The location of the     

AlGaAs／GaAs HBT表面效应的二维数值分析

采用表面效应集总模型综合考虑表面费米能级钉扎和表面复合效应，对ＡｌＧａＡｓ／ＧａＡｓＨＢＴ表面效应的影响进行了二维数值模拟。结果表明，表面态的存在对集电极电流几乎不产生影响，但显著增加基极电流，使得电流增益明显下降。同时还发现在台面结构ＡＩＧａＡｓ／ＧａＡｓＨＢＴ中外基区表面复合的集边效应，即外基区表面复合主要发生在发射极台面与外基区的交界处附近，与外基区长度基本无关。模拟还表明基区缓变结构可以减少表面复合，提高电流增益。     

Nonlinear distortion prediction of active filters

The represention of circuit variables in frequency-domain complex matrix and nonlinearities by power series gives rise to a nonlinear distortion prediction technique, the intermodulation-balance method. This operates entirely in the frequency domain. The technique is verified by a single-amplifier filter with a two-tone input signal     

铸造合金凝固过程瞬时应力的测试

以计算机采集处理系统为手段,测试了应力框铸件凝固过程的瞬时应力.结果表明,该方法简便、速度快,精度高,可获得铸件凝固过程瞬时应力及温度的动态变化过程。