Global and local heat transfer analysis for bicycle helmets using thermal head manikins

Predicting thermal comfort of protective headgear is of particular interest since the head is one of the most heat-sensitive body parts. Thermal head manikins enable systematic investigation of heat transfer properties of headgear. Such investigation provides valuable inputs for the development of new helmet concepts to improve thermal comfort.This study presents a nine-zone thermal head manikin (9zM) to evaluate local heat transfer effects of headgear. Performance of the new manikin and local data were assessed by comparing with data from a two-zone thermal head manikin (2zM) published previously. Variation for heat flux data was found to be lower for 9zM than for 2zM in tests including convective and radiative heat transfer. The calculation of radiant heat gain revealed similar variation at cranial section for both manikins but it increased at facial section for 9zM. Classification of helmets based on heat transfer data differed for head manikins likely due to slight differences in head geometries. Moreover, local heat transfer data obtained from the 9zM allowed a more detailed investigation of headgear properties. This knowledge contributes to a better understanding of the thermal interaction of head and headgear and, therefore, to a more justified development of optimised headgear designs.     

基于NV色心的晶体管放大器近场分布成像

微波毫米波芯片非破坏高分辨率近场分布成像对高频射频芯片的功能和失效分析至关重要.本实验基于金刚石NV（Nitrogen-Vacancy）色心这一独特的量子体系,选取直径约为14μm的金刚石样品,将其粘附于20μm直径的光纤锥形尖端,制备成高分辨、非破坏、微型化的探针,通过分析NV色心在微波场变化中的基态自旋演化规律,采用全光学的方法,一次性成像,获得芯片表面整体场分布.本文给出了氮化镓高电子迁移率晶体管的近场分布成像图,拟合出光学探测磁共振（Optically Detected Magnetic Resonance,ODMR）谱图以及Rabi谱图,并对成像结果进行了分析.这一系统具有高效、高分辨、高灵敏度、对近场干扰小等优势,有望为高集成度微波电路故障诊断、天线辐射剖面、微波集成电路电磁兼容测试等应用提供一种全新的方案.     

JSTAMP/NV在冲压模具开发中的应用

介绍JSTAMP/NV在冲压模具开发过程中前期、中期和后期等3个阶段的应用和实例,详细阐述对仿真有重要影响的因素,包括坯料网格划分、材料模型、仿真速度和回弹及其回弹补偿精度等.JSTAMP/NV能够减少冲压模具开发成本并缩短开发周期.     

Benchtop Fluorination of Fluorescent Nanodiamonds on a Preparative Scale: Toward Unusually Hydrophilic Bright Particles

Fluorination of diamonds modulates their optical and electromagnetic properties and creates surfaces with increased hydrophobicity. In addition, fluorination of diamonds and nanodiamonds has been recently shown to stabilize fluorescent nitrogen‐vacancy centers, which can serve as extremely sensitive single atomic defects in a vast range of sensing applications from quantum physics to high‐resolution biological imaging. Traditionally, fluorination of carbon nanomaterials has been achieved using harsh and complex experimental conditions, creating hydrophobic interfaces with difficult dispersibility in aqueous environments. Here, a mild benchtop approach to nanodiamond fluorination is described using selective Ag⁺‐catalyzed radical substitution of surface carboxyls for fluorine. In contrast to other approaches, this high‐yielding procedure does not etch diamond carbons and produces a highly hydrophilic interface with mixed C?F and C?OH termination. This dual functionalization of nanodiamonds suppresses detrimental hydrophobic interactions that would lead to colloidal destabilization of nanodiamonds. It is also demonstrated that even a relatively low surface density of fluorine contributes to stabilization of negatively charged nitrogen‐vacancy centers and boosts their fluorescence. The simultaneous control of the surface hydrophilicity and the fluorescence of nitrogen‐vacancy centers is an important issue enabling direct application of fluorescent nanodiamonds as nanosensors for quantum optical and magnetometry measurements operated in biological environment.     

全光学非破坏微波场分布成像

随着技术的进步,微波集成电路的复杂度和集成度都在不断提高,并且其特征线宽也在不断减小,因此非破坏高分辨微波场近场成像技术对芯片的功能和失效分析至关重要,目前尚没有成熟的技术路线。文章提出了一种基于金刚石氮空位色心的固态量子体系作为传感单元,通过分析色心基态自旋在共振微波场中的量子态演化规律,采用全光学的方法,获得微波场分布的一种精密测量方法。该方法通过搭建光学成像系统进行一次宽场成像来获得芯片整体的微波场分布,具有高效、对近场干扰小等优点,有望在芯片电磁兼容测试、微波芯片失效分析和天线近场分布成像等应用上提供一种全新的测量方案。     

基于JSTAMP／NV的汽车前纵梁冲压工艺优化

以国际板材成形数值模拟会议（（Numisheet’2011）上提出的第三个标准考题为例,介绍了利用专业钣金仿真分析JSTAMP／NV软件在对汽车前纵梁执行拉仲成形工艺优化及回弹仿真的应用过程,并将回弹仿真的结果与实验测试结果进行了对比,结果表明：仿真结果与实验结果具有良好的匹配性。     

蓄电池在线智能监测仪的设计

蓄电池作为电力系统的后备电源，其维护工作对保证电力系统的安全运行具有重要意义。对蓄电池实施在线监测并及时发现失效电池，是蓄电池维护工作的重中之重。文中介绍一种以单片机ADuC831为核心的新型蓄电池在线智能监测仪，能实现对蓄电池无论在浮充状态还是充、放电动态过程中的状态检测。着重介绍其软硬件设计方法。     

钣金冲压成形仿真软件JSTAMP/NV2.7.2新功能介绍

详细介绍了钣金冲压成形仿真软件最近发布的新版本JSTAMP/NV_V2.7的新功能及其应用。     

基于Y-U模型的高强度钢板冲压回弹预测

随着高强度钢板在汽车车身中得到越来越广泛的应用,如何通过数值模拟准确预测冲压件的回弹显得日益重要。本文应用冲压成形有限元分析软件JSTAMP/NV中针对高强度钢板的回弹预测的材料本构关系Y-U模型,对某汽车车身制件进行了冲压成形分析及回弹预测,其回弹量与实验现场所得扫描数据相一致,与企业提供的同类软件的计算结果相比较,具有明显的优势。     

JSTAMP/NV2.5新增功能应用研究

以国际板材成形数值模拟会议(Numisheet2002)的标准考题翼子板为例,并在JSTAMP/NV中进行冲压成形仿真模拟,论述了JSTAMP/NV2.5版新增功能的应用方法与过程。