用比较电桥校准直流电阻箱(电桥)示值的测量不确定度分析

用比较电桥测量直流电阻箱的示值误差,分析对测量结果的影响因素,评定其不确定度。     

(Pb1-xSrx)TiO3系铁电陶瓷介电特性的测试分析

采用常规陶瓷工艺掺杂不同含量的分析纯SiO2和La2O3,在不同烧结温度下, 制备了系列(Pb1-xSrx)TiO3(简称PST)铁电陶瓷.对所制备的PST铁电陶瓷的介电特性进行了测试分析.1250℃烧结温度较1200℃烧结温度下样品在居里点处的温度系数α有所提高,介电常数ε略高(均在103量级),介电损耗D略有降低.随着工作频率的增加,样品介电常数有较明显的下降,介电损耗D略有增加.     

铅(土寿)法炸药作功能力测试的几个问题

文章分析了用铅(土寿)法进行炸药作功能力测试时经常碰到的几个问题,阐述了用铅(土寿)法进行炸药作功能力测试的几点技术建议,为从事炸药性能检测者提供参考经验.     

Ca1-xBaxZr4(PO4)6磷酸盐陶瓷材料的热膨胀特性

Ca1-xBaxZr4(PO4)6(0≤X≤1.0)属于NZP族磷酸盐陶瓷材料,它是新的一类低热膨胀陶瓷材料。研究发现CaZr(PO4)6(X=0)及BaZr4(PO4)6(X＝1)时的轴膨胀特性正好相反,因此当X为某一值时热膨胀系数将为零。本研究采用共沉淀法合成了Ca1-xBaxZr4(PO4)6磷酸盐陶瓷材料,当X＝0时,热膨胀系数为－0．86×10-61／℃;当X＝0．25时热膨胀系数为2．7×10-61／℃;当X＝0．75时其热膨胀异向性最小。为了得到热膨胀异向性和热膨胀系数均小的Ca1-xBaxZr4(PO4)6磷酸盐陶瓷材料,X应在0．6至0．9之间,并通过控制烧结条件抑制晶粒的生长。     

基于GM(1,1)的建筑废弃物资源化利用研究

针对建筑废弃物难以量化问题,通过面积指标法,估算历史年份的建筑废弃物产量,建立了基于灰色系统理论GM(1,1)的产量预测模型.以国内某城市为例,预测"十四五"期间建筑废弃物产量,并提出建筑废弃物处理与资源化利用的相关措施.     

色差公式CMC(1:c)、CIE94和CIEDE2000的对比研究

色差是评印刷包装产品质量的一个重要参数,在孟塞尔新标数据集的基础上,用PF/3方法对CMC(1:c)、CIE94和CIEDE2000三个色差公式进行了对比分析,结果表明在该数据集下3个色差公式的性能相差不大.     

本科毕业论文(设计)教学计划的问题刍议

新时期本科毕业论文(设计)教学存在诸多困境.本科生撰写毕业论文(设计)是教学计划的一个重要组成部分,只有正确认识教学计划中毕业论文(设计)的学术属性,解决毕业论文(设计)教学的时间问题,才能不降低要求,不放任自流,确保毕业论文(设计)的教学水平.     

Preparation of Nano-structured LiFe_xMn_(1-x)PO_4(x=0,0.2,0.4) by Reflux Method and Research on the Influences of Fe(Ⅱ) Substitution

Nano structured LiFexMn1-xPO4(x=0,0.2,0.4) materials were successfully prepared by one-step reflux method in a water/PEG400 mixed solvent, and were coated by carbon using glucose as the precursor. The materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The electrochemical properties of the materials were investigated by galvanostatic cycling, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that the materials consisted of nanorods with a diameter of 50 nm and a length of 500 nm. Galvanostatic cycling showed that the capacity of LiMnPO 4 could be largely increased by Fe2+ substitution. At a current rate of C/20, the capacity of the three samples (x=0,0.2,0.4) were 47, 107 and 150 mA·h·g-1 , respectively. CV result showed that the Fe2+ substitution could decrease the polarization during charging/discharging, accelerating the electrochemical process. EIS result showed that the Fe2+ substitution could decrease the charge transfer resistance between the electrode and electrolyte,     

对同步流密码设备的相关性功耗分析(CPA)攻击

利用同步流密码的再同步弱点,提出了用相关性功耗分析(CPA)攻击同步流密码的技术,该技术采用统计学中的相关系数来分析密钥并实施攻击.概括了CPA技术的攻击过程,给出了CPA攻击两个同步流密码A5/1和E0的步骤和实验.实验证明,用CPA攻击同步流密码是可行的.最后给出了有效的防御对策来抵抗这种攻击.     

磷灰石(AP)的制备及其成分比较晶体化学与吸F行为的研究

首次采用成分比较晶体化学的研究方法,利用XRD、FT—IR、TEM、DTA/TG等于段,研究合成磷灰石的成分晶体化学特征与除氟行为的关系。用sol-gel法制备了不同CO_3~(2-)掺量的等粒——短柱状碳羟磷灰石(CHAP);用两步控温均相沉淀法制备了平均长宽比可控的CHAP晶须;以胶原蛋白为模板,用仿生合成法制备了片状CHAP。采用高斯函数法拟合,建立了CHAP中CO_3~(2-)的AB混合型替换模型:在FT—TR谱中非对称伸缩振动峰Ψ_3分裂为Ψ_(3-1)、Ψ_(3F)、Ψ_(3-4),Ψ_(3F)是A型替换的Ψ_(3-2)与B型替换的Ψ_(3.3)的叠合。随CO_3~(2-)含量增加,当W CO_3~(2-)≤3.34％时,替换指数(SI)增大,且当W CO_3~(2-)=3.34％时,SI达最大值;当3.34％相似文献   

Subcooled liquid density measurements and PvT measurements in the vapor phase for 3,3,3-trifluoroprop-1-ene (R1243zf)

The fluorinated propene isomer R1243zf (3,3,3-trifluoroprop-1-ene, CF₃CFCH₂, CAS number 677-21-4) is a potential alternative refrigerant with short atmospheric lifetime, low-GWP, and low acute toxicity; however, because of its flammability it is being considered primarily as a component in blends. In this paper, 302 subcooled liquid density data and 101 vapor phase PvT data are presented. The subcooled liquid density data are measured for eight isotherms, evenly separated approximately from 283 K to 353 K, for pressures from close to saturation to 35 MPa and the vapor phase PvT data are measured for six isochores for temperatures approximately from 278 K to 368 K and for pressures approximately from 260 kPa to 912 kPa. In addition, a saturated liquid density correlation, a Tait correlation for the subcooled liquid density data, and a Martin–Hou Equation of State for the vapor phase PvT data are presented.