Effect of 8 MeV electron irradiation on electrical properties of CuInSe2 thin films

Radiation damages due to 8 MeV electron irradiation in electrical properties of CuInSe₂ thin films have been investigated. The n-type CuInSe₂ films in which the carrier concentration was about 3×10¹⁶ cm⁻³, were epitaxially grown on a GaAs(0 0 1) substrate by RF diode sputtering. No significant change in the electrical properties was observed under the electron fluence <3×10¹⁶ e cm⁻². As the electron fluence exceeded 10¹⁷ e cm⁻², both the carrier concentration and Hall mobility slightly decreased. The carrier removal rate was estimated to be about 0.8 cm⁻¹, which is slightly lower than that of III–V compound materials.     

Crack redirection with thermal secondary loading

In the current paper crack redirection due to a strategic placing of a heat source in the vicinity of a crack tip is studied. Analysis suggests that for PMMA and considered temperature range the only factor responsible for the deviation of crack trajectory is thermal stress. The simulation of crack growth in PMMA under external tension and secondary heat loading shows that a moving heat source in the vicinity of a crack tip can serve as a pointer for the crack trajectory. In highly conductive materials, redirection can be possibly effected with low-power thermal dipoles.     

牙哈采油树腐蚀检查分析及对策

介绍塔里木牙哈凝析气田高温高压井口采油树腐蚀的现象，腐蚀机理及采取的措施，对其他油田采油树腐蚀的防治起到指导借鉴作用。     

混凝土多孔砖应用技术研究

在分析了多孔砖力学特点的基础上,通过分析和研究,找出克服由于设计、施工原因造成的混凝土多孔砖砌体强度下降的措施。     

Multiwalled Nanotubes: Their Formation by Irradiating Graphite with High Doses of Electrons

We report the production of carbon nanotubes by high dose of electron irradiation. The irradiation was performed with a 2 MeV Van de Graaff accelerator, while the irradiation conditions were the following: voltage 1.3 MeV, current 5 µA, dose rate 25 kGy/min, and total dosage 1000 kGy. The samples were analyzed in a high-resolution transmission electron microscope. The main features observed on the samples, were huge nanotubes of several nanometer long and few nanometer wide, which are capped at one end. It is good to point out, that at this level of irradiation, we were not able to find either onion-like or particle structures throughout the material, as it is usual in similar hexagonal structures. This behavior could be attributed to the level of irradiation used to create the nanotubes under investigation.     

超低渗广谱油层保护技术在板深51区块的应用

板深51区块存在压力敏感地层，在非目的层井段存在大段高渗低压砂岩，而目的层又属于高压低渗地层，属于难采油气田。室内进行的砂床滤失量、砂床封堵带承压能力、岩心封堵带的承压能力及油气层保护效果实验表明，在超低渗钻井液中增加固相含量，能够提高超低渗透膜结构强度，提高地层承压能力，降低砂床侵入深度，增强保护油气层效果，而且有选择性地增加有用固相效果更佳。基于这一理论，研究成功了超低渗广谱屏蔽暂堵油层保护技术，并在板深51区块长22—15井和长23—17K井进行了试验应用。该技术的关键是依据地层特性确定复配暂堵剂。长22-15井和长23-17K井射孔后未经过压裂、酸化、排液处理，获自喷高产，尤其是长22-15井形成自喷油流，创油田单井试采产量最高记录。应用结果表明，超低渗广谱保护油气层钻井液技术封堵隔层的承压能力强，很大程度地提高了漏失层的承压能力和破裂压力，较好地解决了含多套压力层系长裸眼段钻井过程中发生的漏失、井喷、卡钻、油气层保护等技术难题。     

静载荷和疲劳载荷作用下 C/Al 正交层压板的力学响应

本文讨论静载荷及疲劳载荷作用下 C/Al 正交层压板的力学响应,并考虑损伤过程中的临界现象,以此作为结构设计准则的基础。对静载荷作用的情况:(1)90°铺层的门槛应变ε_(FPF)随着约束程度增加而增加,而且开裂后的行为也受约束程度的影响。(2)经历加载-卸载再重新加载至断裂的过程后,初始试样存在一个剩余永久变形,其损伤状态可以用刚度的变化来表征;而疲劳试样在加载-卸载过程中刚度变化很小,反映其损伤达到一个稳定的状态。对疲劳载荷作用的情况:(1)对于给定的应力比 R,试样会趋于与它所承受的 S_(max)最大值相应的 SDS 状态。循环应力范围的不断增大,会引起基体损伤的增加,从而重新建立新的饱和损伤状态。(2)对于每一损伤状态均有一对应的循环应变范围 Δε。在 SDS 状态下,Δε保持不变。(3)以刚度下降为损伤参数对 C/Al 层压板进行了降级应力分析,并由此来预计在ΔS_(sh)以下,层压板不会发生疲劳损伤累积。     

高功率激光系统通过空间滤波和中继成像抑制自聚焦

讨论了由光束自聚焦引起的细丝形成和光束分裂，为了克服聚焦造成的破坏要求在光束传播中采用中继成像和空间滤波。     

砼受压损伤力学本构模型的研究

本文利用ＭＴＳ公司８１５．０２型电液伺服试验系统对砼进行了等应变速率加载控制的应力一应变全曲线试验，应用不可逆热力学和内变量理论的成果建立了砼损伤力学模型，并用概率统计的观点分析了损伤的演化规律。由于考虑了不可逆变形的影响，本文所建本构模型与实验吻合较好。     

LOW-CYCLE FATIGUE UNDER NON-PROPORTIONAL LOADING

A series of strain-controlled, low-cycle fatigue experiments have been conducted on 42CrMo steel under various loading paths including circular, square, cruciform, and rectangular paths. Present experiments have shown that there is additional hardening under non-proportional cyclic loading. Non-proportional cyclic additional hardening also results in a shorter life for multiaxial low cycle fatigue. A non-proportionality measure of strain path based on both a physical basis and macromechanical phenomena is proposed. The loading path effect on additional hardening is also described well. Low-cycle fatigue damage accumulation and the evolution process under non-proportional loading is analysed via the Continuum Damage Mechanics Model of Chaboche. A non-proportinality measure is introduced in the damage evolution equation and a modified Coffin-Manson type formula is derived. A novel fatigue life prediction approach based on the critical-plane concept of Brown and Miller is proposed.