Analysis of deep excavations in clay under the undrained and plane strain condition with small strain characteristics

The nonlinearity and small strain characteristics of clay are predominant factors to affect the analysis accuracy of surface settlement induced by deep excavation in soft clay. In this study, we use a newly developed constitutive model, namely the undrained soft clay model, to simulate the nonlinearity of soft clay and to describe the degradation of elastic Young's modulus with the increasing stress level, ranging from small strain to near failure. The parameters of the formula can be obtained from conventional soil tests. One well-documented case history is then used to show the parameter determination procedure and validate the proposed model. The states of strain and stress paths for the soil in the excavation are also studied to validate the rationality of the model. Besides, two additional case studies are conducted to verify the model further.     

Work-related chronic injuries of the forearm and hand: their specific diagnosis and management

Work-related chronic injuries occur in muscles, tendons, and nerves. Epidemiological, histological, and physiological data confirm their often disputed physical basis. Terms such as repetitive strain injury and cumulative trauma disorder, when used as a diagnosis, have obscured the issue for they are really statements of causation. Definitive diagnosis is required both to treat and prevent such injuries. Precise terminology that identifies the tissue and its pathology is required. A detailed assessment methodology is described that allows a precise diagnosis. A clear relationship to work stress is necessary both to establish the cause and formulate prevention strategies. Treatment must begin early and be appropriate to the tissue and the nature of the injury. Examples are presented and discussed. Early treatment begins before too much damage has been done and yields better results.     

OPGW的应力应变特性--有关标准的差异和讨论

根据IEEE1138、IEC60794和DL／T832标准对OPGW典型的应力应变特性做了评估，可以看出这些标准之间的差异。文章提出：只有当OPGW中的光纤余长是均匀时，应力应变测试结果才有实际意义。     

Flexible and Highly Sensitive Strain Sensors Fabricated by Pencil Drawn for Wearable Monitor

Functional electrical devices have promising potentials in structural health monitoring system, human‐friendly wearable interactive system, smart robotics, and even future multifunctional intelligent room. Here, a low‐cost fabrication strategy to efficiently construct highly sensitive graphite‐based strain sensors by pencil‐trace drawn on flexible printing papers is reported. The strain sensors can be operated at only two batteries voltage of 3 V, and can be applied to variously monitoring microstructural changes and human motions with fast response/relaxation times of 110 ms, a high gauge factor (GF) of 536.6, and high stability >10 000 bending–unbending cycles. Through investigation of service behaviors of the sensors, it is found that the microcracks occur on the surface of the pencil‐trace and have a major influence on the functions of the strain sensors. These performances of the strain sensor attain and even surpass the properties of recent strain sensing devices with subtle design of materials and device architectures. The pen‐on‐paper (PoP) approach may further develop portable, environmentally friendly, and economical lab‐on‐paper applications and offer a valuable method to fabricate other multifunctional devices.     

1310nm大功率高偏振度量子阱超辐射发光二极管

设计并制备了一种斜条脊波导结构压应变高偏振度多量子阱超辐射发光二极管.设计的脊波导出光面TiO2/SiO2四层宽带增透膜的TE模式反射率约为10-6,分析了脊波导角度偏差和膜层厚度偏差对增透膜反射率的影响.实验结果表明,在250 mA直流电流驱动下,所设计的超辐射发光二极管芯片单管输出功率可达22.7 mW,出射光谱FWHM约为37.3 nm,光谱纹波系数低于0.15 dB,TE模式输出光强占主导,偏振度约为19.2 dB.     

高强度光纤光栅与碳纤维的复合及应变传感特性研究

针对光纤光栅工程化应用性能不佳的问题,提出将高强度光纤光栅与碳纤维材料复合,介绍了复合样品的结构形式,分析了应变传递过程,然后对其应变传感特性和疲劳性能进行了实验研究。结果表明:复合样品能够达到较高的应变传递效率,具有良好的应变传感特性;疲劳实验中复合样品保持正常工作,波长变化曲线的幅度稳定;疲劳实验前后复合样品的应变传感特性基本不变,应变灵敏度系数分别为1.12和1.17pm/με,应变响应曲线的线性度均高于0.999,重复性分别为0.623%和0.397%。     

应变硅技术在纳米CMOS中的应用

应变硅技术具有迁移率高、能带结构可调的优点,且与传统的体硅工艺相兼容,在CMOS工艺中得到广泛地应用,尤其是MOS器件的尺寸进入纳米节点。文章综述了应变硅技术对载流子迁移率影响的机理,并从全局应变和局部应变两个方面介绍了应变硅在CMOS器件中的应用。同时,将多种应变硅技术整合在一起提升MOS器件的性能是未来发展的趋势。     

量子阱材料折射率低偏振相关性研究

分析了阱宽、垒高和应变对量子阱材料TE模和TM模折射率的影响,并剖析了其中的物理机理.研究表明:对于量子限制效应带来的量子阱折射率偏振相关性,阱宽越小或垒高越高,折射率偏振相关性越大.压应变增大时,折射率偏振相关性增大,张应变可以克服量子限制效应带来的折射率偏振影响.对于不同阱宽和垒高的量子阱,均存在合适的张应变量使折射率偏振相关性最小,且阱宽越小或垒高越高所需的张应变量越大.根据以上分析,提出量子阱材料折射率低偏振相关设计方法,并据此设计出C波段(1 530～1 565 nm)内折射率低偏振相关(小于0.03)的量子阱材料In0.49Ga0.51As/In0.77Ga0.23As0.5P0.5.研究结果有助于优化设计光网络中关键器件.     

相移光纤光栅应变传感特性的实验研究

用非平衡Mach-Zehnder干涉仪检测动态应变在相移光纤光栅中感生的波长变化,对2.1kHz信号进行FFT(快速傅立叶变换)频谱分析得到了2.1×10-2με(1με=1×10-6应变)的应变分辨率(信号分析带宽5kHz)。     

拉拔成型无氧铜管在爆轰加载下的膨胀及断裂特性研究

为了探索拉拔成型无氧铜管是否满足标准圆筒试验的延展性要求,采用未经二次锻造的粗晶软态无氧铜,通过拉拔成型工艺加工成25 mm圆筒试验用的标准铜管。采用超高速分幅相机及扫描相机分别观测装填TNT炸药及JO-159炸药条件下的铜管膨胀及断裂过程,对比典型高应变率范围内铜管的断裂应变、裂纹扩展方向等差异,并分析铜管应变能对炸药驱动性能表征参数的影响。结果表明：TNT炸药爆轰加载下,铜管裂纹主要沿母线形成及扩展,其破片主要呈条状;而JO-159炸药爆轰加载下,铜管环向应变率及轴向应变率分别约为TNT炸药加载工况的1.34倍和2倍, 其断裂带易出现较为复杂的交错状态,形成密集小破片;这两种炸药爆轰下,该铜管的断裂直径均达到了初始直径的3倍,且表征炸药驱动性能的格尼速度未发生明显变化,因此可以满足一般高能炸药圆筒试验的要求。