热处理条件对IrO2-pH电极性能的影响

在700℃炉冷、870℃空冷和炉冷三种热处理条件下,制备了氧化铱pH微电极,并对比了微电极的线性范围及响应时间.结果表明:热处理条件对Ir氧化物膜的均匀性有很大影响,进而影响其开路电位的稳定性及响应速度.700℃炉冷和870℃空冷制得的电极氧化膜表面粗糙,孔隙率不均匀并伴随有裂纹;而870℃炉冷条件下制得的电极具有表面氧化膜均匀、响应时间短以及线性好等优点.铱氧化物的形成机理是Ir丝被空气中的O2氧化,而高温Li2CO3起到一种溶剂的作用.铱氧化物电极的H+响应是由于电极表面水合氧化铱与溶液中H+发生化学反应,反应为Ir4+与Ir3+之间的转变.     

基于模糊梯度的微齿轮图像边缘检测算法

提出一种基于模糊梯度思想的微齿轮图像边缘检测算法.该算法采用正切归一化函数对灰度图像模糊化,并计算该模糊图像的梯度矩阵;采用正弦函数对梯度矩阵进一步模糊化得到模糊梯度矩阵;采用基于归一化实数编码的遗传算法来搜索最优的阈值λ对模糊梯度矩阵做截集,获取图像边缘点集合.实验中以不同微齿轮图像作为实验对象,测试了该算法性能.实验结果表明,该算法的检测精度优于10μs,检测时间基本为1s,整体性能优于Canny算法和Pal-King算法.     

模m二次剩余系之Wilson定理

主要研究了模m二次剩余系之Wilson定理,研究表明,若模m有原根,-1为模m的二次剩余,则模m的二次剩余系全体元素之积modm的同余数为-1;若不然,则模m二次剩余系全体元素之积modm的同余数为1。且模m二次非剩余系全体元素之积与二次剩余系全体元素之积modm的同余数相反。若m无原根,则模m二次剩余系全体元素之积与二次非剩余系全体元素之积modm的同余数相等。     

多场耦合作用下煤层气的渗流特性与数值模拟

根据实验研究煤样在轴向应力、围压、气压、温度单一因素作用下的渗流规律.利用Ansys12.0数值模拟了单场与多场耦合作用下煤层气的渗流规律,煤体的变形、孔隙压力、渗流场的分布规律.数值模拟得出:单场作用下煤层气在煤体中的渗流规律实验与数值模拟结果基本相同;多场耦合作用下煤的渗透率与平均有效应力曲线呈负指数关系;对试件变形的影响应力场大于渗流场,轴向应力对试件的变形大于围压;围压对渗流场的影响大于轴向应力,轴向应力对孔隙压力的影响大于围压,多场作用下孔隙压力大于单场作用.多场作用下数值模拟的结果与实验研究是一致的,因此研究煤层气的渗流规律必须考虑气-固-热的同时作用.     

使用前景/背景区域率失真特性的码率控制方法

为提高视频编码器码率控制的性能,根据视频内容将视频帧划分成包含主要运动物体的前景区域和相对静止背景的背景区域,分析各区域的率失真特性,提出一种适用于H.264/AVC编码器的基于区域的宏块层码率控制方法. 比特分配中,根据宏块的区域信息确定加权因子,自适应地为重要宏块分配较大的目标比特预算. 不同区域使用对应参数的二次模型确定宏块量化参数(quantization parameter,QP),并以已编码宏块的QP为参考调整计算所得QP,以降低前景与背景区域间、相邻宏块间的编码质量波动. 宏块编码结束后,根据实际编码信息更新各区域的码率控制参数. 实验测试表明,提出方法能够有效降低实际码率与目标码率之间的相对偏差,提高编码效率和解码恢复视频的主观质量。     

隧道健康动态评价模型与应用

在隧道健康安全评价的指标体系及其等级标准的基础上,通过规范化处理样本资料库中的元素,消除了指标类型和量纲的影响后,提出用集对分析方法构造可变模糊集的相对差异度函数,合理的确定了各层相关隧道健康评价指标处于级别标准区间的相对隶属函数,采用乘积标度法确定相关指标权重后,得出了隧道健康模糊综合评价动态模型。确定健康级别指标特征值后,结合实例计算证明了文中所提方法的科学性与合理性,有利于推动可变模糊集理论在土木工程领域的进一步发展。     

石膏不同组份对孔隙率的影响

通过多种方式配制石膏(CaSO4·2H2O)并测定其垂直吸水高度h、在水平状态下的输水速度u、孔隙率η及平均孔隙半径等物理性质,发现多孔介质石膏的上述特性与配制方法关系极大。石膏是由CaSO4加适量的水而形成2水硫酸钙(CaSO4·2H2O),随水量增加孔隙率增大而其强度下降。在水中加入少量柠檬酸钾配制时,会大大改善其多孔介质性能,垂直吸水高度、水平输水速度及孔隙率可分别达到：120 cm、4.2 mm/min及69.4%,可以作为毛细吸液芯辐射板的内填充物使用。     

An overview of resistive random access memory devices

With recent progress in material science, resistive random access memory (RRAM) devices have attracted interest for nonvolatile, low-power, nondestructive readout, and high-density memories. Relevant performance parameters of RRAM devices include operating voltage, operation speed, resistance ratio, endurance, retention time, device yield, and multilevel storage. Numerous resistive-switching mechanisms, such as conductive filament, space-charge-limited conduction, trap charging and discharging, Schottky Emission, and Pool-Frenkel emission, have been proposed to explain the resistive switching of RRAM devices. In addition to a discussion of these mechanisms, the effects of electrode materials, doped oxide materials, and different configuration devices on the resistive-switching characteristics in nonvolatile memory applications, are reviewed. Finally, suggestions for future research, as well as the challenges awaiting RRAM devices, are given.     

Mitochondrial DNA variation analysis suggests extreme low genetic diversity in Guizhou snub-nosed monkeys （Rhinopithecus brelichi）

Guizhou snub-nosed monkey (Rhinopithecus brelichi) is a unique, endangered primate in China, mainly distributed in Fanjing Mountain National Natural Reserve, Guizhou Province, in an area of 275 km2. Recently, habitat loss and fragmentation have caused population isolation. To assess genetic diversity within this species and its population structure, we sequenced 400 bp of the hypervariable I segment from the mitochondrial DNA control region for 128 individuals. Only one haplotype was identified from these individuals. Compared with other primate species, R. brelichi can be regarded as a species with very low genetic diversity, which further adds to the conservation concern.     

Does flagship species tourism benefit conservation? A case study of the golden snub-nosed monkey in Shennongjia National Nature Reserve

Tourism has been widely used as a conservation strategy that directly compensates local people or management authorities, thereby contributing to development and creating incentives to preserve the landscape. Reserves or parks that are inhabited by flagship species may be able to generate more revenue through tourism than those without such species because flagship species have great potential for raising funds and creating publicity for conservation goals. In this paper, we examine flagship species tourism...