基于卷积神经网络的5G蜂窝网络无线定位方法

5G蜂窝网络发展迅猛，其覆盖面积将逐渐增大，因此使用5G蜂窝网络进行定位是有研究潜力的研究方向。本文提出一种新的深度学习技术来实现高效、高精度和低占用的定位，以代替传统指纹定位过程中繁重的指纹库生成以及距离计算。该方法建立了一个特殊的卷积神经网络，并根据5G天线信号的接收信号强度指示、相位和到达角等特征量，选择合适的输入数据格式构造样本组建训练集，对该卷积神经网络进行训练。训练得到的卷积神经网络可以替代指纹定位中的庞大指纹库，非常有利于直接在5G移动设备端实现定位。虽然卷积神经网络在训练过程中需要大量时间，但在训练完毕后直接进行分类定位的速度非常快，可以保障定位实现的实时性。本文所实现的卷积神经网络权重与偏置所占内存不到0.5 MB，且能够在实际应用环境中以95%的定位准确率以及0.1 m的平均定位精度实现高精度定位。     

Analytical methods for superresolution dislocation identification in dark-field X-ray microscopy

Journal of Materials Science - We develop several inference methods to estimate the position of dislocations from images generated using dark-field X-ray microscopy (DFXM)—achieving...     

Cognitive and metabolic workload assessment techniques: A review in automotive manufacturing context

Ergonomics assessment in the automotive industry has, to date, focused mainly on physical ergonomics, for example, manual handling and posture. However, workload and, in particular, metabolic and cognitive workload, contributes to worker efficiency but has not received sufficient attention to yield practical guidance for industry. Successful workload assessment requires in-depth understanding of the context in which it will be conducted and of the various assessment techniques which will be applied, with consideration given to factors such as feasibility, resources, and skill of the assessor. These requirements are met with challenges within large and complex organizations and are often dealt with in a piecemeal and isolated matter (i.e., reactive workload assessment). The present paper explores these challenges within the automotive manufacturing industry and aims to develop a decision matrix to guide effective selection of workload assessment techniques focused on metabolic and cognitive demands. It also presents the requirements for time, equipment, and knowledge to implement these techniques as part of a participatory ergonomics approach. Early findings suggest that most assessment techniques reviewed require further development, for example, to establish the acceptance criteria for the specific workload scenario. However, five methods (Garg, Borg RPE, IPAQ, SWAT, and NASA-TLX) are ready to use in certain applications. Ultimately, the findings suggest that it is possible to implement a participatory workload evaluation program within large and complex manufacturing plants.     

Feasibility of glioblastoma tissue response mapping with physiologic BOLD imaging using precise oxygen and carbon dioxide challenge

Magnetic Resonance Materials in Physics, Biology and Medicine - Innovative physiologic MRI development focuses on depiction of heterogenous vascular and metabolic features in glioblastoma. For this...     

Downward Flame Spread Rate Over PMMA Rods Under External Radiant Heating

Fire Technology - There are multiple situations in which fires may occur at environmental conditions that are different than standard atmospheric conditions. Changes in ambient pressure, oxygen...     

Cold sintered,temperature-stable CaSnSiO5-K2MoO4 composite microwave ceramics and its prototype microstrip patch antenna

Dense (1-x)wt%CaSnSiO₅-xwt%K₂MoO₄ (CSSO-KMO) composite ceramics were fabricated by the cold sintering process at 180 °C under 400 MPa for 60 min. X-ray diffraction, Energy dispersive X-ray and Raman spectroscopy confirmed that CSSO and KMO coexisted without intermediate phases. As KMO weight fraction increased, relative permittivity (ε_r) and temperature coefficient of resonant frequency (τ_f) decreased and the microwave quality factor (Q×f, where f is resonant frequency) increased. Near-zero τ_f (-0.5 ppm/°C) was obtained for 65 wt%CSSO-35 wt%KMO with ε_r ～ 9.2 and Q×f ～ 6240 GHz. No chemical reaction between ceramic composites and silver was observed, demonstrating potential for cofiring with Ag-paste. A prototype antenna was fabricated from 65 wt%CSSO-35 wt%KMO composite ceramic with a bandwidth of 144 MHz @ -10 dB, a gain of 5.7 dBi and a total efficiency of 88.4 % at 5.2 GHz, suitable for 5 G mobile communication systems.     

Development of mullite fibers and novel zirconia-toughened mullite fibers for high temperature applications

Polycrystalline mullite fibers and novel zirconia-toughened mullite (ZTM) fibers with average diameters between 9.7 and 10.3 μm containing 3, 7 and 15 wt.-% tetragonal ZrO₂ (ZTM3, ZTM7, ZTM15) in the final ceramic were prepared via dry spinning followed by continuous calcination and sintering in air. A shift in the formation of transient alumina phases and tetragonal ZrO₂ to higher temperatures with increasing amounts of ZrO₂ was observed. Concomitantly, the mullite formation temperature was lowered to 1229 °C for ZTM15 fibers. X-ray diffraction revealed formation of the desired tetragonal crystal structure of ZrO₂ directly from the amorphous precursor. Room temperature Weibull strengths of 1320, 1390 and 1740 MPa and Weibull moduli of 9.5, 7.1 and 9.0 were determined for mullite, ZTM3 and ZTM15 fibers, respectively. Average Young’s moduli ranged from 190 to 220 GPa. SEM images revealed crack-free fiber surfaces and compact microstructures independent of the amount of ZrO₂.     

一种新型的室温快速固化胶黏剂的研制

本文开发了一种新型的方舱夹芯板用室温固化高强度环氧结构胶黏剂,验证了其物化特性、相关力学性能和环境适应性。结果表明此胶黏剂具有优良性能,可以满足方舱用大板胶黏剂的使用需求。     

基于Newmark法两端支座松动拉杆转子动力学分析

建立了具有两端轴承基座松动故障的拉杆转子模型(松动轴承基座质量称为松动质量块,松动轴承基座与地面连接的刚度称为松动刚度),并推导了其运动微分方程.基于分离变量法和Sturm-Liouville理论得到了有限长滑动轴承油膜力近似解析解,运用Newmark法分析了该转子系统的非线性动力学行为.首先,将无故障转子、一侧轴承基座松动和两侧轴承基座松动转子系统动力学进行比较,结果显示存在松动故障的转子具有更加复杂的动力学行为,而且存在松动故障的转子振幅比无故障转子的振幅大.其次,对两端轴承基座松动情况进行了分析,结果表明转子系统存在着周期、周期三、周期五、周期六、周期七、准周期和混沌等运动形式.同时发现,随着转子转速升高,松动质量块的振动幅度也随之增大.当两端松动质量和松动刚度不同时,松动质量较大或者松动刚度较小的一侧,转子的振幅和松动质量块的振幅较大,随着两侧松动质量和松动刚度差值的增加,两侧转子的振幅和松动质量块的振幅的差值也随之增加.