实时全息干涉计量用于研究岩石材料正向受压形变

采用实时全息干涉计量摄影系统，记录岩石试件正向受压下干涉条纹的形变规律。配合声发射定位测量，可以测定岩石试件微裂纹扩展时间、位置和强度。初步的实验已经观察到干涉条纹是在空间定域的，微裂纹的扩展与局部应力的集中有关，且其延伸方向是应力场高梯度变化的方向等，这种方法的成功将为脆性材料的损伤研究提供一种可视化的研究手段。     

应对道路石油沥青技术要求新规范

通过对代表性的国产和进口沥青性质分析,考察国产和进口重交通道路石油沥青、瞢通道路石油沥青对交通部新修订《道路石油沥青技术要求》规范的适应性。结果表明:绝大部分重交沥青产品在针入度指数(PI)指标不能满足新修订规范中A、B级沥青的技术要求,大部分重交沥青产品TFOT后针入度比指标不能满足交通部《道路石油沥青技术要求》规范中A、B级沥青的技术要求,部分重交沥青产品在60℃粘度和TFOT后10℃延度指标不能满足规范中的技术要求。部分普通道路沥青在15℃延度、TFOT后针入度比和TFOT后15℃延度指标上不能满足规范中C级沥青的技术要求。     

A 13-bit resolution ROM-less direct digital frequency synthesizer based on a trigonometric quadruple angle formula

A ROM-less direct digital frequency synthesizer employing trigonometric quadruple angle formula is present in this paper. The worse case spectral purity is better than -130 dBc. The amplitude resolution is up to 13 bits, while the phase resolution is 12 bits. Neither any scaling table nor error correction tables are required. The maximum error is mathematically analyzed. The word length of each multiplier is carefully selected in the digital implementation such that the error range is circumscribed and the resolution is preserved.     

在石墨基体上脉冲电镀TiB2镀层

采用KF KCl K2 TiF6 KBF4 和LiF KF NaF K2 TiF6 KBF4 熔盐体系 ,利用直流和脉冲电源在石墨基体上制备了TiB2 镀层。采用金相显微镜观察了镀层的厚度 ,用X射线衍射分析了镀层的组成 ,用扫描电镜观察了镀层的表面形貌。实验结果表明 :在LiF KF NaF K2 TiF6 KBF4 熔盐体系 ,当K2 TiF6 ∶KBF4 为 1∶4(摩尔比 ) ,脉冲电流幅度为 0 .45A·cm- 2 ,脉冲宽度为 85ms,脉冲间隔为 1 7ms时 ,得到的镀层致密、无裂纹、与基体的结合力很好、有金属光泽、TiB2 的纯度高。     

Identification of Nck family genes, chromosomal localization, expression, and signaling specificity

Already a dozen molecules share binding to the Src homology (SH) 3 domains of human Nck, an SH3-SH3-SH3-SH2 adapter protein. We reason that there may be multiple gene members of Nck to accommodate the large binding repertoires. Here we report identification of novel human and mouse Nck genes and rename them as the Nckalpha and Nckbeta genes (including the human Nckalpha, human Nckbeta, mouse Nckalpha, and mouse Nckbeta genes). Nckalpha and Nckbeta share 68% amino acid identity, whereas the two Nckalpha and two Nckbeta across the species show 96% identity to each other. The human Nckbeta gene is mapped to 2q12, whereas the human Nckalpha gene has previously been mapped at 3q21. Antibodies specifically against Nckalpha and Nckbeta detect Nckalpha and Nckbeta with an identical molecular mass in the same cells of various origins. Ectopically expressed Nckbeta, but not its SH2 domain mutant, strongly inhibits epidermal growth factor- and platelet-derived growth factor-stimulated DNA synthesis. Consistently, epidermal growth factor receptor and platelet-derived growth factor receptor preferentially interact with Nckbeta over Nckalpha in vitro. This study indicates that Nck is a multiple gene family and that each gene may have its own signaling specificity. Because previous anti-Nck (human Nckalpha) antibodies cross-react with Nckbeta, reassessment of those studies with specific Nck genes would be necessary.     

Statistical analysis of fracture in graphite

A statistical model is proposed to study the fracture of graphite. This model, based on a more general one proposed by She et al., uses a local fracture criterion for a microcrack, a distribution function for microcracks and the weakest link principle to predict failure probability as a function of applied loading and distribution of microcracks. The model considers the effect of the three-dimensional stress state and therefore gives a general representation of both the effects of complex loading and microcrack distribution. The inputs to the model can be determined by either studying the microstructural features of the graphite or by choosing inputs to make the model prediction fit a set of experimental results. The latter method is used to apply the model to failure results of Rose and Tucker. One set of results is used to calibrate the model which is then applied to predict the failure behavior of a second set of experimental results. Finally, the effect of the various input variables on failure probability is studied first by considering a graphical representative of failure probability as a function of input variables and second by writing the equations in terms of nondimensional variables.     

原油罐长效综合防腐蚀技术及试验对比

对原油储罐长效综合防腐蚀技术在设计、应用及测试方面与普通阴极保护防腐蚀技术进行了对比。该项技术应用于原油储罐 4年后的检测结果表明 ,其工作电位为 - 0 .89V ,仍满足设计规范要求 ,而且具有安装简便、使用灵活等特点。该项技术也可应用于容器、换热器及管线的电化学保护。     

All‐optical switching modulation in poly(vinyl carbazole)—based azobenzene blends

We report on the all‐optical switching polymer blends based on photoconductive poly(vinyl carbazole) (PVK) and azobenzene dyes. The optical switching effects of the blends were measured by using a 514 nm pump beam and a 632.8 nm probe beam. The blends' photoinduced reversible and repeatable change in the transmittance of the probe beam is attributed to the photoinduced anisotropy of the azobenzene dyes. The influencing factors of the optical switching effect, such as the modulation frequency and pump beam intensity, were studied experimentally.     

Quantitative Magneto-Optical Imaging for Superconducting Thick Films and Tapes

Practical superconducting thick films and tapes, manufactured in an industrial process, have microscopic inhomogeneities. Quantitative magneto-optical imaging (MOI) is one of the most desirable techniques and provides both local and global information on defects, flux pinning, critical current density J _c, and current distribution. We present, herein, a comparative magneto-optical imaging study of the flux profile in YBa₂Cu₃O_7−δ (YBCO) thick films prepared in two different processes, the laboratory versus the industrial scalable process. The remarkably different flux propagation patterns are the manifestation of their different defect landscapes within these films. A method of determining J _c near zero applied field is also given for locally nonuniform superconducting films, using the quantitative MOI technique.