Observations on dual-ended readout of 100 mm long LYSO crystals

We are investigating using dual-ended readout of axially oriented long thin scintillator crystals in detectors for a compact geometry, small ring diameter animal PET system. The axial position of interaction is determined from the light sharing between two photodetectors at opposite ends of the crystal. We examine the light output, energy resolution and axial spatial resolution of 1.5-5×2×100 mm³ polished LYSO crystals by irradiating with an electronically collimated beam of 511 keV photons oriented perpendicular to the long axis and read out at either end by position sensitive photomultiplier tubes (PSPMTs). Three reflector materials, namely Teflon, 3 M enhanced specular reflector (ESR) and black paint are examined for the 2×2×100 mm³ crystal size. The light output increases and energy resolution improves with the crystal cross-section. Generally, the spatial resolution worsens with increase in crystal cross-section. For the 2×2×100 mm³ crystal size, the mean energy resolutions of the photopeak over the nine irradiation positions were 14.4±0.4%, 16.0±1.2% and 28.3±2.1% with mean spatial resolutions of 7.0±1.0, 9.4±3.3 and 26.0±5.0 mm using ESR, Teflon and black paint, respectively. ESR reflector gave the best light output, energy and axial spatial resolutions. These characterization results of PSPMT-based dual-ended long LYSO crystals will be useful in the design of detector modules for a highly compact geometry preclinical PET system using this detector technology.     

Study on Cleanliness of High Quality Steels in Shouqin

Study on cleanliness of high quality steels in 100t basic oxygen furnace was carried out by "Hot Metal Desulphurization-Basic Oxygen Furnace-Ladle Furnace Refining-RH Refining-Continuous Casting" process. High-quality low-carbon ultra thick slabs were produced with 0.04%≤wC≤0.08%, wS≤0.002%, wP≤0.008%, wN≤0.004%, wH≤ 0.0002%, wT[O] ≤0.0015%. A series of key technologies for content control of carbon, phosphorus, sulfur, nitrogen, hydrogen and inclusions were determined, which has laid a foundation for the development of the high-degree steel.     

X100高强度管线钢管组织性能及焊接性能研究

通过万能材料试验机及光学金相、SEM(扫描电子显微镜)、TEM(透射电子显微镜)等手段,研究了X100管线钢管的力学性能及组织构成.分析表明,钢管管体主要为粒状贝氏体及少量多边形铁素体混合组织,具有良好的强度和韧性;X100管线钢的热敏感性较大,在焊接热循环作用下过热区的组织更容易长大,造成热影响区发生软化和脆化,成为...     

高速光传输系统的发展与展望

介绍了当前高速传输系统的现状,详细描述了100G、40G WDM的应用现状和技术发展,针对目前40G WDM的应用情况以及100G WDM的发展方向进行了分析,最后对下一步光网络技术向超100G迈进的发展方向进行了展望     

回火态AerMet100钢的热物理性能

AerMet100钢是一种先进的二次硬化型Ni-Co-Cr系结构钢,通过试验获得了回火态AerMet100钢的密度、热应变、弹性模量、泊松比、热导率、流变应力随温度的变化情况,以及升温过程奥氏体转变Ac₁和Ac₃点,降温过程马氏体转变Ms点和马氏体转变系数K_m。最后基于获得的回火态AerMet100钢热物理性能数据,以齿轮淬火过程为例,采用SYSWELD有限元分析软件进行了仿真分析。结果表明,回火态AerMet100钢的室温组织为回火马氏体+残留奥氏体,在升温过程中奥氏体反应热焓为42 600 J/kg,其他热物理性能参数均在Ac₁~Ac₃范围内发生非线性变化,且测试状态和升温速度不同导致Ac₁和Ac₃存在差异,回火态AerMet100钢不同冷却速度下的Ms基本一致,约为213 ℃,马氏体转变系数K_m值为0.011 736。SYSWELD有限元仿真分析表明,试验获得的各项热物理性能数据可用于该钢的热处理模拟分析。     

利用水溶性植物功能蛋白生产饲用油脂粉末的研究

介绍了SVFPl00的产品特性及营养价值，分析了利用SVFPl00生产饲用油脂粉末的优点，并提供了利用SVFPl00生产饲用油脂粉末的工艺流程。     

分段最小二乘拟合法在变压器测温中的应用

基于长春某500 k VA变电站,针对变压器温度测量过程中铂电阻温度传感器Pt100数据采集误差较大的问题,通过对铂电阻非线性特征的研究,提出一种将负电阻补偿法与分段最小二乘拟合法相结合的方法从外部对传感器信号进行误差修正,经实际测试,该方法能有效提高测量精度、减小误差,且适用性好,补偿后的传感器能满足大多数场合要求。     

基于ATmega16和AD7709的路基温度采集系统

针对路基温度人工采集费时困难的现状,提出了基于ATmega16的多通道路基温度采集系统.以Pt100为路基温度传感器,用74LS138和74HC4051设计了128路通道切换电路,用ATmega16和AD7709构建了温度采集系统,并进行了温度标定试验.试验结果表明:系统能实现多通道温度采集功能,测量误差为0.4℃,满足路基温度测量要求.     

浊点萃取-192紫外可见分光光度法测定痕量铝

研究了浊点萃取(CPE)-紫外可见分光光度法测定痕量铝离子的新方法,利用非离子表面活性剂Triton X-114对铝试剂与铝离子形成的络合物进行浊点萃取。探讨了影响浊点萃取及测定灵敏度的因素。在最佳条件下,铝离子的富集倍率为13.5倍,检出限为0.33μg/L,RSD为0.2%(n=6),铝离子含量在10~150μg/L范围内服从比尔定律。本法对实际样品中的铝进行富集和测定,结果令人满意。     

A review on the mechanical and electrical properties of graphite and modified graphite reinforced polymer composites

Carbon materials particularly in the form of sparkling diamonds have held mankind spellbound for centuries, and in its other forms, like coal and coke continue to serve mankind as a fuel material, like carbon black, carbon fibers, carbon nanofibers and carbon nanotubes meet requirements of reinforcing filler in several applications. All these various forms of carbon are possible because of the element's unique hybridization ability. Graphene (a single two-dimensional layer of carbon atoms bonded together in the hexagonal graphite lattice), the basic building block of graphite, is at the epicenter of present-day materials research because of its high values of Young's modulus, fracture strength, thermal conductivity, specific surface area and fascinating transport phenomena leading to its use in multifarious applications like energy storage materials, liquid crystal devices, mechanical resonators and polymer composites. In this review, we focus on graphite and describe its various modifications for use as modified fillers in polymer matrices for creating polymer-carbon nanocomposites.