现实生活中,电子设备的线管在使用时经常会出现缠成一团,使用麻烦而且拆线时容易将线折断的问题。为了方便对线管的使用,提高线管的使用寿命,不造成不必要的浪费。从卷尺的设计出发,提出了一种可以对线管进行收缩的器具。其依靠扭簧,使线管达到收缩的效果。与其它现有集线装置相比,其适用范围广、便于拆卸,更具有安全与实用性,在日常生活中可以发挥更大的作用。

In real life,the electronic equipment of line pipe when use frequently,tie up into a bal ,when using the trouble and remove the problems easy to be broken line.In order to facilitate the use of line pipe,and improve the service life of line pipe,don''t cause unnecessary waste.Starting from the design of tape measure,put forward a kind of line pipe can be instruments of contraction.Its depend on the torsional spring,make the pipe line to achieve the effect of shrinkage.Compared with other existing set line device,its applicability is wide and easy to remove,is more safe and practical,can play a more important role in our daily life.

采用基于密度泛函理论的第一性原理方法研究了β-碳化硅/(15,0)碳纳米管和β-碳化硅/(16,0)碳纳米管核壳结构的电子结构特性.结果表明,两种核壳异质结构都呈现出金属性,它们的金属性主要是由碳纳米管和碳化硅纳米线表面的原子所贡献的.碳化硅纳米线表面呈现的金属性由其结构本身决定,而对于金属性的(15,0)和半导体性的(16,0)碳纳米管在填充碳化硅纳米线之后都表现出金属性,主要是由于碳纳米管和碳化硅纳米线之间的电荷转移导致的,而并不是由于碳纳米管形变造成的.

@@@@The structural and electronic properties ofβ-SiC/(15, 0) carbon nanotube (CNT) andβ-SiC/(16, 0)CNT core-shell structure are studied by using first-principles method based on the density functional theory. The results show that the two heterostructures are metallic. Their metallic properties are contributed by the atoms from the CNTs and the surface of SiC nanowires. The metallic property of the SiC nanowire is determined by its structure. However, the fact that the metallic (15, 0) and semiconducting (16, 0) CNTs both show the metallic properties after filling the SiC nanowires, is due to not the deformation of CNTs, but the charge transfer between CNTs and SiC nanowires.

目的评估两种电子根尖定位仪的准确性。方法选临床291例患者385根根管随机分为3组:传统X线测量组120根管;EA(L迷你型root-ZX根尖定位器)132根管;多功能电测根管马达(VDW电测仪)133根管,测定各根管工作长度(WL)。用ProTaper镍钛锉将根管预备到F3尺寸,选择适合F3锥度的主牙胶尖充填以保证根管充填的密闭性。结果 3种测量方法之间恰充情况,传统X线测量组106根管(88.3%);EAL组123根管(93.2%);多功能电测根管马达组126根管(94.7%),无显著统计学差异(χ2=3.865,P=0.145)。结论两种根尖定位仪的准确性与传统X线WL测定技术有较为明显的优势,但二测量仪之间无显著差别。

Objective To evaluate the clinical accuracy of two electronic apex locators (EALs). Methods A total of 291 patients with 385 roots were randomized into three groups including, traditional radiographic method(120 root canals), EAL (Root ZX mini,132 root canals), and apex locating endodontic motor (VDW ,133 root canals ) for working length (WL) determination. Root canals were instrumented to a size ProTaper F 3 nickel titanium file. The obturation quality of matched tapered master cone was determined for the accuracy of WL. Results The traditional X-ray group 106 root canals (88.3%);EAL group 123 root canals (93.2%);VDW group 126 root canals (94.7%), The accuracy of three methods had statistically there was no signiifcant differences. (χ2=3.865, P=0.145). Conclusion The accuracy of the two kinds of root apex locator with traditional X-ray WL measurement technology has more obvious advantages, but there was no signiifcant difference between two measuring instrument.

海洋环境变化多端,钢悬链线立管(SCR)在复杂的环境荷载作用下容易发生疲劳破坏而影响安全,为研究立管在环境荷载作用下的动力响应,本文利用ABAQUS有限元软件对SCR建模,在立管上部悬挂点施加位移边界条件模拟浮体的运动,在立管的触地段采用刚度基于P-y曲线的非线性弹簧单元模拟立管与海床的相互作用,并通过调节立管环境荷载参数,研究了浮体运动、波浪振幅、周期和海流速度等参数对钢悬链线立管动力响应的影响。结果表明:钢悬链线立管随着环境荷载参数的变化呈现出不同的动力响应,立管对浮体的垂荡运动更敏感;波浪的振幅越大、周期越小,立管触地点与悬挂点的动力响应越大;海流速度增大,悬垂段长度会变大。

The marine environment is changeful .The steel catenary riser is prone to produce fatigue dam-age so as to affect the safety of production on effect of complex marine environmental load .In order to study the dynamic response of the riser under environmental load , the paper built SCR model by use finite element software ABAQUS .By applying displacement boundary condition on the upper suspension point of the riser to simulate the movement of floating body , using the nonlinear spring whose stiffness is based on P-y curve to simulate the riser-soil interaction , adjusting the parameters of environmental load on the ris-er,it studied the influence of floating body motion , wave amplitude , wave period and current velocity on SCR dynamic response .The results show that the steel catenary riser presents different dynamic response with the change of environmental load , the riser is more sensitive to heaving motion of floating body;the larger the wave amplitude ,the less is its period , the

目前阿赛线进站温度远高于凝点,且清管频繁。清管通球作业中蜡多,堵塞加热炉进口,过高的进站油温也使得加热炉过烧。利用普适性蜡沉积模型,预测了阿赛线不同进站温度下,正常工况及保温层破损条件下管输原油的蜡沉积规律。结果表明,阿赛线蜡沉积主要集中在进站处。据此提出了管道新的清管方案,并优选了新的进站温度。夏季和春秋季管道进站温度取35℃,冬季管道进站温度取40℃。现场数据表明预测结果和实际吻合良好,平均相对误差9.49%。

At present ,the operating inlet oil temperature to the pump station along Asai pipeline is much higher than the gel point of the crude oil .And the pigging frequency is much higher .There is much waxes removed from the pipeline during the pigging operation .It not only blocks the inlets of heating furnace ,but also consumes more thermal energies .In this paper ,the wax deposition profiles of the crude oil along Asai pipeline at different inlet temperatures under normal conditions were predicted by using the unified wax deposition model , and also the wax deposition distribution under the condition from damaging thermal insulation was also examined .The prediction results show that the wax deposit mainly accumulated in the inlets of the pump stations .On this basis ,a new pigging program involving pigging frequency was proposed ,and the same time the inlet oil temperature was also optimized to be a lower value .In winter ,the inlet oil temperature is advised to be 40 ℃ . While in other