体育学力外显-内隐双结构模型的建立

以体育学力为研究对象,采用理论分析、访谈分析、调查分析和逻辑分析对体育学力结构进行研究。研究表明:体育学力是学生经过体育课程学习应该获得的从事体育实践活动的能力。体育学力的整体结构是以体育健身能力、体育娱乐能力、体育观赏能力和体育学习能力为外显要素,以体育态度、体能和运动认知、体育知识技能为内隐要素的双结构体系。

Effect of pin profile and process parameters on microstructure and mechanical properties of friction stir welded Al-Cu joints

In friction stir welding(FSW), pin profile has more influence on material flow especially in welding of dissimilar materials with different yield strengths. In the dissimilar welding of aluminium and copper, the material flow behaviour is complex to understand and thus a study is needed to reveal the mechanism of flow behaviour and the resultant mechanical properties. Three pin profiles, whorl pin profile(WPP), plain taper pin profile(PTP) and taper treaded pin profile(TTP) were chosen. The effects of pin profile on the microstructure, microhardness and tensile properties were studied. Optical microscope, scanning electron microscope, X-ray diffraction and EDS analysis were used to characterize the microstructural features. Among the three pin profiles, PTP profile results in defect-free stir zone and maximum joint properties of yield strength of 101 MPa, tensile strength of 116 MPa and joint efficiency of 68% compared with the other pin profiles. However, the microhardness plots are more or less identical for all the pin profiles but follows fluctuating trend. This is attributed to the heterogeneous distribution of hard Cu particle. The superior joint properties are mainly attributed to the defect-free stir zone formation and dispersion strengthening.

The relationship between IR characteristic peak and microstructure of the glass used as optical fiber

Based on the harmonic vibration equation, the relationship between IR characteristic peak of fiberglass and Si-O-Si bond angle was deduced, and 1 100 cm^-1 characteristic peak was specifically studied. It is found that 1 100 cm^-1 characteristic peak shifts to higher wave number when Si-O-Si bond angle increases. Taking fused biconical taper （FBT） coupler as an example, the microstructures of the fiber coupler manufactured at different draw- ing speeds were tested with micro infrared spectrum. According to the test results, it is found that the bond angle at the taper region is the largest, the one at the fused region is the second largest, and the one of bare fiber is the smal- lest. The characteristic peaks of fused-taper region shift to higher wave number when drawing speed increases.

Microstructure and properties of novel polarization maintaining fiber

An improved type of elliptical jacket polarization maintaining fiber was developed by using a modified chemical vapor deposition method with special treatment. Different from conventional elliptical jacket, the shape of the stress jacket was transmuted. The cross-section of fiber consists of 5 layers: substrate, outer cladding, stress jacket, inner cladding and core. The cross sectional component distribution was investigated by electron probe microscopy and energy dispersive spectrum. The finite element method was used to calculate the stress birefringence. Based on the analyses of the microstructure, the technological process is improved. The temperature cycling test of the fiber wound into gyroscope coils was performed. The results show that the fiber possesses superior performance at high and low temperatures compared with other fibers. The high homogeneity is achieved by well-controlled modified chemical vapor deposition process. A homogeneous length of 8 km fiber is obtained. With advantages in homogeneity and length, the fiber has great potential in applications such as fiber gyroscopes, fiber hydrophone and other optical fiber sensors.

数据中心系统新概念及逻辑分析

信息是人类社会进步的基础。数据中心作为人类社会进入信息时代的重要标志,开启了人类文明史的新起点。本文以新的占位理念,通过对数据中心各系统概念的解析,深入析数据中心系统的构成,旨在理清数据中心系统结构的逻辑关系,对于制定数据中心最佳应用策略;实现数据中心高效低碳的发展需求;加快数据机房的系统专业化进程;构建未来人类社会的硅基大脑具有深远的意义。

Te-seeded growth of few-quintuple layer Bi2Te3 nanoplates

We report on a Te-seeded epitaxial growth of ultrathin Bi2Te3 nanoplates （down to three quintuple layers （QL）） with large planar sizes （up to tens of micrometers） through vapor transport. Optical contrast has been systematically investigated for the as-grown Bi2Te3 nanoplates on the SiO2/Si substrates, experimentally and computationally. The high and distinct optical contrast provides a fast and convenient method for the thickness determination of few-QL Bi2Te3 nanoplates. By aberration-corrected scanning transmission electron microscopy, a hexagonal crystalline structure has been identified for the Te seeds, which form naturally during the growth process and initiate an epitaxial growth of the rhombohedral- structured Bi2Te3 nanoplates. The epitaxial relationship between Te and Bi2T% is identified to be perfect along both in-plane and out-of-plane directions of the layered nanoplate. Similar growth mechanism might be expected for other bismuth chalcogenide layered materials.

Biomaterials for refractive correction:corneal onlays and inlays

Corneal inlays and onlays represent a means of providing patients with permanent refractive error correction. As an alternative to conventional spectacles and contact lens, these techniques are less invasive compared with laser-based refractive surgery and are reversible. In this review, we provide a brief overview of the anatomic microstructure of the human cornea, indicating the primary physiological function for each component. Next, the wide range of biomaterials used as corneal inlays and onlays are considered, from synthetic polymers to biological components derived from the extracellular matrix. The limitations and challenges associated with the most common materials are discussed as is the need to improve their properties to achieve long-term, complication-free intraocular implantation. Finally, the prospect of applying tissue engineering strategies is noted for its potential to generate autologous corneal tissue that could be implanted as the optimal inlay or onlay materials.