张坝沟石灰石矿边坡控制爆破的现状

张坝沟石灰石矿长期采用光面爆破技术来减小爆破震动及后冲对固定边坡的危害.文中较详细的介绍了矿区地质条件、光面爆破的设计及施工中的问题,对倾斜孔非对心不耦合装药边坡爆破的效果进行了评价,建议采用多种控制目的的穿孔工作方法.     

户式蓄冷空调系统的实验研究与经济性分析

提出将现有普通家用空调器改造为直接蒸发式内融冰蓄冷空调系统的方案.对户式蓄冷空调进行了实验研究,分析了其经济性.提出了开发蓄冷空调的几点建议.     

Operando Reconstruction of Porous Carbon Supported Copper Selenide Promotes the C2 Production from CO2RR

Precisely regulating surface reconstruction of copper (Cu) chalcogenides-based catalysts to promote the multicarbon (C₂₊)selectivity of the electrochemical CO₂ reduction reaction (CO₂RR) is hampered by the challenging control of the intractable anions and the optimal Cu^δ+ reduction (0 < δ < 1). Herein, a porous carbon-supported copper selenides electrocatalyst that can remarkably improve the C₂-product yield and especially unveil the time-revolved electrochemical CO₂RR reconstruction process to enable the high C₂-selectivity, most notably for ethanol is constructed. The Faradic efficiency (FE) of C₂-products achieved is as high as ≈85.2% with a partial current density of 229.5 mA cm⁻². Operando infrared spectroscopy and density functional theory (DFT) calculations unravel that the surface Se vacancies (V_Se) formation brings closer the neighboring Cu⁺ atoms and activates the Cu sites, thereby rendering efficient generation of the key intermediates (^*CO and ^*CHO) and lowering the C–C coupling barrier for C₂ production. The appearance of metallic Cu can shorten the next-nearest Cu⁰–Cu⁺ distance for O atom to bridge in, leading to the preferential formation of ^*OC₂H₄ towards ethanol instead of C–O bond cleavage to form ethylene. This work opens the avenue of designing suitable local atomic structures catalysts to engage the intermediates for targeted CO₂RR products.     

Design of cavern blasting based on controllable parameters

After a thorough review of some controllable parameters, which included field investigations, cavern dimensions, explosive, rock strength etc., cut, contour, lifters and stoping holes were introduced for blasting cavern of nucleus submarine. These design were conducted using a U. Langefors and B. Kihlstrom theory. Supported by the Navy Cavern Project Foundation of China (02)     

High performance active image sensor pixel design with circular structure oxide TFT

We report a high-performance active image sensor pixel design by utilizing amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with a circular structure. The TFT, configured with the inner electrode as source and outer electrode as drain, typically exhibits good saturation electrical characteristics, where the device has a constant drive current despite variations in drain voltage. Due to the very high output resistance exhibited by this asymmetric TFT structure with a circular shape, the pixel circuit considered here in common-drain configuration provides a higher gain of operation than a pixel circuit implemented with rectangular a-IGZO TFTs. They can be used as driving TFTs in active image sensor circuits. They are, therefore, good candidates for digital X-ray detectors in applications such as medical diagnostic procedures.     

电子产品在焊接过程中的可靠性探究

制备了一种新型Sn-9Zn-2.5Bi-1.5In钎料,开发了一套波峰焊氮气保护系统,考察了该钎料在不同氧含量的环境下的焊接质量. 结果表明,开发的氮气保护系统通过增加氮气流量可以将焊接区域内的动态氧含量降低到0.06%以下. 降低焊接区氧含量,可显著减少桥连、填充不良、气孔3类缺陷的数量,将不良率控制在0.20%以内. 在氧含量0.50%的临界值以下,该钎料可在锡炉设定温度为225 ℃的条件下进行低温焊接,焊接效果满足规模化生产需求. 通过能谱分析发现氧化物表面Zn元素含量比Sn-9Zn-2.5Bi-1.5In钎料升高84.9%,Zn元素的易氧化倾向是导致钎料形成大量氧化渣的主要原因. 降低焊接区域的氧含量可以有效抑制氧化渣的形成.采用氮气保护的方法可以解决Sn-Zn钎料在高氧环境下易出现的焊接缺陷问题,从而实现225 ℃低温波峰焊.     

The effect of oxygen on the epitaxial growth of diamond

We studied the effect of oxygen on the growth quality of diamond epitaxial layers. After oxygen is added during the growth of the diamond epitaxial layer, as the thickness of the epitaxial layer increases, the full width at half maximum of the rocking curve of the (004) plane of diamond epitaxial layer increases continuously, and, in addition, the intensities of both the Raman peaks and the free exciton emission peaks of the diamond epitaxial layer decrease continuously. These experimental results demonstrate that as the thickness of the diamond epitaxial layer increases, the quality of the diamond epitaxial layer degrades. The strong etching effect of the OH radical groups in the plasma on the diamond epilayers leads to the degradation of their crystallinity.     

Numerical study of scattering Legendre moments and effect of anisotropic scattering on SN shielding calculation

The main purpose of this work was to perform a rigorous computational study on scintimammography with a Mura-mask based on Monte Carlo simulation of voxelized breast phantoms. Three main objectives were addressed:(1) verification of Geant4 version 10.4,(2)optimization of the imaging setup, and(3) small tumor detection and localization. We successfully verified the Geant4-based imaging of a commonly used phantom in the field. We used a Mura-mask with a 41× 41 array pattern with adjustable thickness, material, and hole shape(box and cylinder); a low-energy high-resolution collimator with different hole shapes(cylinder and hexagon); and a voxelized breast phantom with different sizes(small, medium,and large) and glandularity percentages(low, medium, and high). We also compared the detector crystal outputs of CdZnTe and NaI(Tl). The simulation was followed by a deconvolution procedure, and the data(images) were statistically emphasized. Statistical metrics indicate that the Mura-mask(W material with 1.5 mm thickness and box holes) combined with a CdZnTe detector leads to the optimum point spread function. Finally, a preliminary study on small-sized tumor detection and localization was conducted with different tumor-to-background ratios(from2 to 12). Tumors with diameters of 5 and 8 mm could be detected, while those of 2 mm were undetectable. Nevertheless, this study enhances our understanding of the early detection of tumors in the field of scintimammography.     

Effect of W on formation and properties of precipitates in Ni-based superalloys

The formation and properties of precipitates in wrought Ni-based superalloys with different W contents during long-term exposure to high temperatures were inves...     

轻型钢结构组合房屋应用问题探讨

阐述国内轻型钢结构组舍房屋在发展和应用中存在的问题,并提出改进建议与同行探讨。