课程文献中心 更多>>

关键词： 陆地探测1号卫星   辐射误差   极化误差   热带雨林   合成孔径雷达  

摘要： 作为中国新一代天基长波SAR的代表,陆地探测1号01卫星(LT-1A)于2022年1月发射进入太阳同步轨道。LT-1A搭载的长波合成孔径雷达(SAR)工作在L波段,具备单极化、线性双极化、紧缩双极化、全极化等对地观测能力。现有研究主要侧重于LT-1A重轨干涉数据获取能力以及数字高程模型、沉降产品的生产精度评价,对LT-1A的辐射精度、地物极化信息保持能力的研究较为缺乏。该文以热带雨林植被为观测对象,通过不依赖人工定标器的自主定标方法对LT-1A全极化数据辐射误差、极化误差的稳定性进行评价与分析。实验表明:LT-1A传感器的辐射稳定性较好、极化精度优于国际对地观测组织(CEOS)推荐指标。持续对地观测1000 km内归一化雷达截面(NRCS)误差波动小于1 dB(3倍标准差)、5天内重返观测时辐射误差波动小于0.5 dB(3倍标准差);全极化观测模式下系统串扰低于-35 dB甚至达到-40 dB,交叉极化通道不平衡优于0.2 dB与2°,同通道不平衡优于0.5 dB与10°;系统噪声介于-42~-22 dB,平均系统等效热噪声优于-25 dB,热噪声水平随持续对地观测时长的增加有升高。此外,该研究验证了电离层对LT-1A极化数据质量的影响:5°法拉第旋转角造成的图像退化与-20 dB系统串扰带来的影响相当,而3°~20°法拉第旋转角在中、低纬度较为常见,这将带来-21.16~-8.78 dB的极化通道间扰动,即电离层对全极化数据质量的退化相较传感器-40 dB的串扰更为严重。

关键词： McKean-Vlasov随机微分方程   共同噪声   自适应Euler-Maruyama算法   Lévy过程  

摘要： 研究了一类带共同噪声和Lévy过程驱动的McKean-Vlasov随机微分方程的数值方法,其中方程系数满足超线性增长条件.对相应的交互粒子系统构造了自适应Euler-Maruyama算法,并给出了该数值算法的收敛速率.

关键词： 全麦生鲜面   热烫处理   品质特性   面筋蛋白   贮藏  

摘要： 为改善全麦制品的品质和贮藏稳定性,探究了不同温度瞬时热烫和面处理(60~90℃)对全麦生鲜面品质、微观特征及贮藏稳定性的影响。与空白(25℃)相比,经过热烫处理的全麦生鲜面蒸煮损失和吸水率显著降低,面片纵向拉伸强度提高;90℃处理组的煮后硬度和咀嚼性增加。扫描电子显微镜图像显示,热烫处理所制备的全麦生鲜面表面更加致密,随温度的升高面筋网络团聚现象更明显,与淀粉颗粒结合更加紧密;淀粉颗粒形态完整,未发生明显溶胀。热烫处理使全麦生鲜面中面筋蛋白聚合程度增加,谷蛋白-醇溶蛋白聚集体生成量随处理温度的上升显著提高;α-螺旋和无规则卷含量增加,β-转角的含量减少。此外,80℃以上热烫处理后全麦生鲜面初始菌落总数显著降低,货架期延长2倍以上,并一定程度上抑制生鲜面褐变。

关键词： 冻干粉针剂   灯检工序   质量管控  

摘要： 目的 提升冻干粉针剂灯检工序的质量管控水平。方法 对冻干粉针剂灯检工序流程中人、机、料、法、环、测6个方面的管控要求进行总结和分析。结果与结论 通过对冻干粉针剂灯检工序进行规范化管控,可有效控制人为差错,提高灯检人员快速识别和准确剔除不合格品的能力,保障产品上市质量。

关键词： 钻孔灌注桩   变形监测   稳定性   支护体系  

摘要： 基坑是建筑工程施工中最为常见的一种结构物,在基坑施工过程中,往往伴随周边建筑物、地下管线以及道路出现不同程度的沉降,基坑在开挖后也会出现一定程度的变形和沉降。为验证钻孔灌注桩是否能有效地控制变形和沉降,本文以某建筑工程基坑施工为例,通过对基坑施工重难点、施工期间的稳定性等进行分析,提出了在钻孔、灌注水下混凝土施工期间相关技术措施并进行了监控测量,研究结果表明,基坑周围的沉降和变形能满足要求,证明钻孔灌注桩支护体系能有效地控制基坑变形和建筑物沉降。

关键词： 大孔径   介孔二氧化硅   纳米粒子   后处理法   直接法  

摘要： 【目的】总结大孔径介孔二氧化硅纳米粒子(large-pore mesoporous silica nanoparticles,LPMSNs)的相关研究,探讨LPMSNs在吸附、催化和负载等领域的应用,推动创新开发。【研究现状】综述直接法和后处理法等合成LPMSNs的方法,直接法包括复合模板法、高分子有机模板剂法、有机膨胀剂法;概括在吸附领域、在负载领域、在催化领域的应用。【结论与展望】提出直接法较为依赖有机试剂的使用,采用较为环保的添加剂改进后处理法,有利于克服该情况;后处理法制备须要考虑降低生产成本,利用二氧化硅硅源和有机模板简化合成程序;后处理法须要将后处理过程和目标应用统一考虑。认为中空型、多级孔型LPMSNs的开发与应用是此领域的一个热点;无模板法可以有利于降低成本;开发可生物降解的模板或引用无机试剂代替有机试剂可实现绿色制备LPMSNs;低成本和规模化制备是LPMSNs及传统MSNs走向应用的关键。

关键词： 集装箱空箱   电动堆高机   运动稳定性   全自动无人驾驶  

摘要： 现有的集装箱空箱堆高机主要通过燃油发动机提供动力,随着自动化技术的发展以及国内外对于环保的重视,堆高机的电动化、自动化技术逐渐薪露头角,目前国内外市场尚未推出成熟的全自动无人驾驶堆高机,该领域还是一片蓝海,相关研究甚少。针对港口集装箱堆场领域,提出一种新型全自动无人驾驶电动堆高机设计方案。同时针对该堆高机在几种典型作业下的运动稳定性进行仿真分析,通过提取整机轮胎支撑力的变化验证整机结构设计是否合理。该研究内容也可以作为同类型产品的设计参考,以期为港口物流装备自动化技术发展提供一种新的解决方案。

关键词： Thermal Radiation   Hybrid Nanofluid   Prandtl Number   Stretching Sheet   MATLAB   Bvp4c Shooting Method  

摘要： The low heat conductivity of base fluids poses significant challenges, leading to growing interest in nanofluids, which have shown promise in improving heat transfer compared to conventional fluids. A nanofluid refers to a fluid that contains nanoparticles uniformly distributed within a base fluid, prepared using specialized techniques to ensure stability and long-term performance, making them distinct from conventional mixtures. Freshwater, refrigeration, glycol, or heating oil are examples of base fluids. The base fluid in this investigation is ethylene glycol mixed with hybrid nanoparticles of graphene oxide, gold, and silver. This study aims to examine the Magnetohydrodynamic (MHD) behavior of hybrid nanofluids over a stretching sheet when exposed to heat radiation and a magnetic field. The basic equations undergo appropriate similarity transformations to convert them from nonlinear higher-order partial differential equations to nonlinear ordinary differential equations. The bvp4c method, an inherent function in MATLAB, is employed to solve nonlinear ordinary differential equations (ODEs). The influence of multiple relevant factors, such as thermal radiation, Prandtl number, slip parameter, Biot number, magnetic field, melting parameter, Nusselt number and skin friction against velocity and thermal profiles is being exemplified through the graphs and tables. Velocity decreases with magnetic and slip parameters, while the melting parameter increases it but reduces the thermal profile. Thermal radiation, Biot number, and the presence of a heat source or sink enhance the thermal profile, whereas higher Nusselt numbers and skin friction reduce it while improving convective heat transfer. The study demonstrates a 29.6 % enhancement in the Nusselt number for hybrid nanofluids compared to conventional fluids as the Prandtl number rises from 2.2 to 3.2. Moreover, the heat transfer performance of hybrid nanofluids surpasses that of traditional nanofluids. The results ali

关键词： MATLAB  

摘要：

关键词： thermoelectric   PVDF   carbon nanotube   tape casting   ferroelectric   polarization  

摘要： Flexible thermoelectric (TE) films and devices have potential applications in wearable technology and the Internet of Things. One of the main challenges is how to simultaneously achieve good TE performance and high chemical/thermal stability in air with low cost and large-scale production. To address this, we utilized tape casting to fabricate composite films of polyvinylidene fluoride (PVDF) and multi-walled carbon nanotubes (MWCNTs). In the composite, polar beta-PVDF introduced by hot pressing can decouple the electrical conductivity and Seebeck coefficient and significantly lead to enhanced power factor of MWCNTs/PVDF composite film. As a result, the MWCNTs (60 wt%)/PVDF film has a power factor of 1.1-1.4 mu W m-1 K-2 near room temperature. The film also has excellent flexibility and stability in the air. Its power factor is decreased by only 9% after 1000 bends and can keep stable in air for above 6 months, which is much longer than that (15 days) of Bi2Te3/PEDOT: PSS film. A demo TE device with 10 p-type legs has an output voltage of 11.5 mV and output power of 47.53 nW at a temperature difference of 60 degrees C. The above descriptions make the MWCNTs/PVDF films have a significant advantage in the commercial application of flexible TE devices. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)/(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(PVDF)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(MWCNT)(sic)(sic)(sic)(sic)(sic). (sic) (sic)(sic)(sic)(sic)(sic)PVDF(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic), (sic)(sic)(sic)(sic)MWCNT