InP/GaAsSb type-II DHBTs with GaAsSb/lnGaAs superlattice-base and GaAsSb bulk-base structures

High-performance InP/GaAsSb double heteroj unction bipolar transistor (DHBT) employing GaAsSb/lnGaAs superlattice-base structure is demonstrated and compared with GaAsSb bulk-base structure by two-dimensional simulation analysis. The proposed device exhibits a higher current gain of 257 than the conventional InP/GaAsSb type-II DHBT with a lower current gain of 180, attributed to the tynneling behavior of minority carriers in the GaAsSb/lnGaAs superlattice-base region under large forward base—emitter bias. In addition, a larger unity gain cutoff frequency of 19.1 GHz is botained for the superlattice-base device than that of 17.2 GHz for the bulk-base device.     

克拉玛依油田回注地层水杀菌剂的再次筛选

采油二厂属克拉玛依油田各区块自１９８９年开始使用的注入水杀菌剂ＷＣ－８５，已因水质变化和细菌耐药能力增加而逐渐失效。采油二厂工艺所于１９９３年１月从９种国产杀菌剂中筛选出两种（ＣＳ１０－３ＢＷ－２），在现场试验中以４０ｍｇ／ｌ的浓度交替连续投加，每种使用１月，原用缓蚀剂照用，使处理后注入水中ＳＲＢ、ＴＧＢ含量和腐蚀率都降至行业标准规定的允许值以下。这一工艺已于１９９３年６月投入现场使用。     

农产品真菌毒素混合污染与累积风险评估研究进展

真菌毒素混合污染危害人畜及农作物健康。目前真菌毒素累积风险评估研究多针对常见的混合污染物,且国内研究较少。此外,毒理学数据及居民消费数据较缺乏,科学的采样方法及人体暴露量的测定方法有待改进。本文阐述了现有的农产品真菌毒素混合污染物的累积风险评估方法以及存在的问题,在危害描述方面,不同含量的真菌毒素混合物在不同动物细胞的体内或体外实验中产生的联合毒性存在差异;在暴露评估方面,基于概率评估的膳食暴露评估和基于生物标记物的暴露评估方法研究日益增多;在风险描述方面,已报道的针对真菌毒素的方法包括危害指数(hazard index,HI)和联合暴露限量值指数(combined margin of exposure index,MOET)。提出了开展真菌毒素混合污染风险评估的必要性,以期为保护人体健康、制定真菌毒素混合污染物限量标准和健康指导值提供基础。     

A new method of analyzing the light transmission in leaky and absorbing planar waveguides

In conjunction with a plane-wave approximation and the partial reflection of the light by a layered structure, a simplified method of analyzing the light transmission in leaky and absorbing planar waveguides is presented. Numerical calculations show excellent agreements with the results based on a waveguiding problem.     

基于码书关联网络的基音调制信息隐藏检测

基音调制信息隐藏在进行基音预测时嵌入机密信息,可在低速率语音压缩编码过程中进行高隐蔽性的信息隐藏,文中试图对该种隐写进行检测.文中发现该种隐写将导致压缩语音流中相邻语音帧自适应码书的关联特性发生改变,文中以此为设计隐写分析算法的关键线索.为了量化该种关联特性,文中设计了码书关联网络模型并基于该模型得到了对隐写敏感的特征向量.最后,基于所得特征向量并结合SVM(Support Vector Machine,支持向量机)构建了隐写检测器.针对典型的低速率语音编码标准G.729以及G.723.1的实验表明,文中方法性能优于现有检测方法,实现了对基音调制信息隐藏的快速有效检测.     

基于深度学习的自适应睡枕设计

睡眠质量是影响人体健康的因素之一, 而一个高度合适的枕头能够有效地改善睡眠质量. 大量研究表明, 人在侧躺时所需的枕头高度应大于平躺时所需的枕头高度. 本文提出了一种基于深度学习的自适应睡枕设计方案, 可以识别人的睡姿, 调节枕头高度, 并给出了硬件平台设计、网络模型搭建和移植. 由枕头内部的压力传感器和气压传感器, 分别采集头部对枕头的压力和枕头气囊内的气压, 生成时间序列数据帧, 再通过一维卷积网络(1DCNN)和门控循环单元网络(GRU)结合的网络模型对睡姿进行识别分类, 最后根据不同的分类结果调节枕头高度.     

Synthesis and characterization of amorphous Al–Mg–B prepared by various deposition temperatures

Amorphous Al–Mg–B thin films were synthesized via a combinatorial sputtering approach. The properties of Al–Mg–B films with the varying deposition temperature was investigated. The deposition temperature was found to dominate the hardness of the amorphous as-deposited film. The hardness increases with increasing deposition temperature and may even exceed that of crystalline AlMgB₁₄ material. The high hardness may be attributed to the existence of randomly distributed B₁₂ icosahedra structure. Therefore, the thin film that was deposited on cemented carbide shows well-cutting performances in turning Ti alloy bar. At the same time, an appropriate method of pretreatment is the key to ensure the coating tool with the excellent adhesion by impact fracture test.