景象匹配区选择方法研究

通过试验研究了景象匹配概率与实时图的独立像元数、方差、纹理能量比和互相关峰等图像特征的关系,并以此提出了基于这些图像特征的景象匹配区选择方法。图像测试结果表明,该方法可以成功地规划出满足要求的景象匹配区。     

快速捷变频率合成器的研制

本文介绍一种低杂散低相噪快速捷变频率合成器的实现途径，该合成器采用直接数字频率合成芯片(AD9852)加倍频的方案。为提高频率捷变速度和输出频率精度，采用TI公司的TMS320C31作为控制电路，捷变频时间小于200ns，相位噪声小于—124dBc/Hz/1kHz。     

Serine Hydroxymethyltransferase 1 Is Essential for Primary-Root Growth at Low-Sucrose Conditions

Plant roots are essential organs for absorbing nutrients from the soil or medium. Sucrose functions as a vital carbon source in root development, and sucrose starvation interferes with the redox state of plant cells. However, the mechanism of root growth at sucrose starvation remains unclear. Here, we report that SHMT1 (serine hydroxymethyltransferase 1) plays a crucial role in primary-root growth. SHMT1 mutation caused decreased sugar levels, excessive H₂O₂ accumulation, and severe root-growth arrest at sucrose-free conditions, whereas plants with SHMT1 overexpression had increased sugar and decreased H₂O₂ levels, and longer primary roots. Sucrose supply fully restored root growth of shm1-2, but CO₂ alone could not, and SHMT1 is much more stable in roots than shoots at sucrose conditions, suggesting that SHMT1 accumulation in roots is critical for sucrose accumulation and root growth. Further ROS scavenging by GSH application or ROS synthesis inhibition by apocynin application or RBOHD mutation reduced H₂O₂ levels and partially restored the root-growth arrest phenotype of shm1-2 at low-sucrose conditions, suggesting that SHMT1 modulates root growth via sucrose-mediated ROS accumulation. Our findings demonstrated the role of SHMT1 in primary-root growth by regulating sucrose accumulation and ROS homeostasis in roots.     

三苯基磷中铑的测定(ICP-AES法)

采用等离子发射光谱法测定三苯基磷中铑的含量,采用直接湿法和高压硝化罐两种方法处理样品,并选择了合适的分析谱线和积分时间,方法简便,准确,快速,回收率为95%~104%,相对标准偏差<2.0%,检出限为0.009 5μg/g。     

阵列波导光栅薄膜的制备及性能

以一种特定成分的有机硅为原料,采用溶胶-凝胶法,在硅基片上制备出用于光波导器件的薄膜.通过折射率和厚度测试及XPS成分测试验证了此薄膜具有较好的均匀性、厚度和光学特性,满足光波导器件的要求.分析了溶胶-凝胶法中常见的龟裂现象的原因以及采预防方法.利用这种薄膜结合微电子加工工艺制备出光波导器件阵列波导光栅.     

基于广义归纳逻辑因果模型的知识发现与算法实现

以语言场、广义细胞自动机和广义归纳逻辑因果模型为理论依据,分析了广义因果联系类知识的发现机理,给出了因果联系类知识发现的实现算法.该算法为解决具有随机不确定和模糊不确定性特征的因果联系类知识的发现提供了行之有效的方法.通过算法的运行实例,验证和说明了算法的正确性和有效性.     

High-Q microresonators on 4H-silicon-carbide-oninsulator platform for nonlinear photonics

The realization of high-quality (Q) resonators regardless of the underpinning material platforms has been a ceaseless pursuit, because the high-Q resonators pro...     

On the robustness of median sampling in noisy evolutionary optimization

Evolutionary algorithms (EAs) are a sort of nature-inspired metaheuristics,which have wide applications in various practical optimization problems.In these prob...     

Flash memory based computing-in-memory system to solve partial differential equations

Dear editor, Many emerging non-volatile memories (NVM),such as re-sistive random access memory (RRAM)[1],phase-change memory (PCM)[2],and ferroelectric RAM (FeR...     

大型地震模拟振动台运行对周围场地影响的试验研究

为降低大型地震模拟振动台试验时所引起的振动对振动台实验室以及周边建筑结构内的机床以及精密仪器的影响,提高结构内人员的舒适度,建立了一种频率相关的半主动控制三维隔振楼板系统。提出了一种基于楼板输入加速度主频的on-off半主动控制方法以及相应的频率在线检测方法,开展了振动台试验,进行了正弦波与地震动引起振动的加载。试验结果表明：所提出的频率在线检测方法可以快速有效地检测输入振动波的主频,根据此频率进行的半主动控制可以有效降低楼板的振动响应。为了提高控制效果,实际应用中应尽量降低磁流变阻尼器在低阻尼力模式时的阻尼。