掘进机截割头钻速优化分析

文章基于EBZ120型悬臂式掘进机进行截割临界转速分析优化,通过利用微元法和弹性力学建立力学模型,确定临界状态下,截割头转速解析解,然后深入分析影响截割转速的因素,依据影响程序确定影响介个转速的因素次序,为截割临界转速的确定提供实际操作提供依据。     

稀土La2O3改性脲醛树脂的黏度特性研究

脲醛树脂(UF树脂)胶黏剂具有胶合强度高、制作简单、成本低廉、原料来源丰富等一系列特点,成为我国人造板生产的主要胶种,是市场上需求量最大的胶黏剂之一。但由于在固化时会放出刺激性的甲醛,游离甲醛高,在使用时严重危害人的健康。近年来,随着人们环保意识的提高,生产和使用低毒UF树脂胶势在必行。本文介绍了稀土氧化镧对脲醛树脂的改性过程并对改性后脲醛树脂胶的各项性能进行了测试。本实验通过在不同反应阶段加入稀土氧化镧,分别探讨它们对脲醛树脂胶黏剂性能影响。实验表明:在脲醛树脂胶中加入稀土氧化镧可以增加黏度、固化时间、固含量,并可以减少游离甲醛释放量。     

多级深度还原法制备Ti6Al4V合金粉体的基础研究

目前Ti6Al4V合金粉体的生产方法主要有雾化法、机械合金法和氢化脱氢法,它们都以Kroll法生产海绵钛为基础。使用钛的氧化物作为原料的熔盐电解法和金属热还原法仍处于研究阶段。本文依据变价金属Ti和V的氧化物在还原过程中逐级还原的特性,提出使用金属氧化物(TiO₂, V₂O₅)作为原料的多级深度还原法制备Ti6Al4V合金粉体的新思路。首先计算了TiO₂-V₂O₅-Mg-Ca体系的吉布斯自由能变,结果表明先进行镁热自蔓延反应,后进行钙热深度还原反应制备Ti6Al4V合金粉体在热力学上具备可行性。然后通过实验进行了的验证。镁热自蔓延反应产物酸浸后除去MgO可得到氧含量为15.84%的多孔Ti-Al-V-O前驱体。配入金属Ca后进行深度脱氧可得到低氧Ti6Al4V合金粉体(Al: 6.2wt.%, V: 3.64wt.%, O: 0.24wt.%, Mg: 0.01wt.%, Ca: < 0.01wt.%)。     

鄂尔多斯盆地延长组致密砂岩储层微观孔喉特征差异及其成因

为分析不同沉积与成岩作用改造下致密砂岩储层的孔喉类型及其参数差异，利用物性、铸体薄片、扫描电镜、恒速压汞、图像粒度与X衍射实验结果，对比了鄂尔多斯盆地合水地区延长组长8储层和薛岔地区延长组长6储层的孔喉类型，定量评价了孔喉参数，揭示了形成原因。结果表明，合水地区长8储层孔隙更为发育，粒间孔、溶蚀孔、晶间孔和微孔、弱压实成因缩颈状喉道和溶蚀成因、粘土胶结成因管束状喉道含量高；薛岔地区长6储层的孔隙类型少且发育程度较差，压实成因片状、弯片状喉道含量高。两个区块的孔隙参数差异小，喉道参数差异大，前者大喉道更为发育，喉道差异大，孔喉比大，对渗透率起贡献的喉道分布范围更宽。相同渗透率条件下，前者的平均喉道半径、主流喉道半径和孔喉比大于后者。沉积水动力条件、粒度、碎屑组分、填隙物、成岩作用类型及其改造程度是两个研究区孔隙发育程度不同、喉道类型差异和孔喉参数表现出不同特征的主要原因。     

A Colorimetric Artificial Olfactory System for Airborne Improvised Explosive Identification

The detection of ultralow or nonvolatile target analytes remains a significant challenge for artificial olfactory systems even after decades of development, which severely limits their widespread application. To overcome this challenge, an artificial olfactory system based on a colorimetric hydrogel array is constructed for the first time as a universal representative. As an effective extension of conventional artificial olfactory systems that integrates the merits of its predecessors, the proposed system accurately mimics olfactory mucosa and specific odorant binding proteins using hydrogels endowed with specific colorimetric reagents for the detection of hypochlorite, chlorate, perchlorate, urea, and nitrate. Therefore, the proposed system is capable of detecting and discriminating between these five airborne improvised explosive microparticulates with a detection limit as low as 39.4 pg. Additionally, the system demonstrates good reusability over ten cycles, rapid response time of ≈0.2 s, and excellent discrimination properties, despite significant variation. This proof-of-concept study on colorimetric artificial olfactory systems yields a novel strategy for the direct and discriminative detection of nonvolatile airborne microparticulates.     

面向超导量子计算机的程序映射技术研究

量子程序在量子计算机上执行时可能由于噪声产生错误.先前的量子程序映射策略将量子程序映射至量子计算机中的最健壮的区域上,以获得更高的保真度.在量子计算机上同时映射多个量子程序可以提升量子计算机的通量和资源利用率.但由于健壮资源稀缺、资源分配冲突,并发量子程序映射会导致整体可靠性下降.介绍了量子程序映射,对相关研究进行分类,并深入分析了其特点与区别.此外,针对并发量子程序映射问题提出了一种新的映射策略,包括3个关键设计:1)提出了社区发现辅助量子位划分算法.结合拓扑结构和错误率数据为并发量子程序进行物理量子位划分,提升初始映射可靠性,避免健壮资源的浪费.2)引入了跨程序SWAP操作,降低了并发量子程序的映射开销.3)提出了一种量子程序映射任务的调度框架,用于动态选取并发量子程序,在保证量子计算机保真度的前提下,提升了通量.所提策略较先前工作在程序执行保真度上提升了8.6％,节省了11.6％的映射开销.所设计的系统是一个面向量子计算机的操作系统原型——QuOS.     

High-rate capability of carbon-coated micron-sized hexagonal TT-Nb2O5 composites for lithium-ion battery

With excellent specific capacity, superior cycle stability, safety and strong practical, Nb₂O₅ has been considered as one of the prospective anode materials for lithium-ion batteries (LIBs). However, current study suggests that Nb₂O₅ electrode materials for LIBs still face the vital issues of low electrical conductivity and poor rate performance. Therefore, carbon-coated TT-Nb₂O₅ materials are designed and synthesized through solid state method in this work, which present high specific capacity (228 mA h g^?1 at 0.2C), satisfactory rate properties (107 mA h g^?1 at 20 C). The outstanding electrochemical property can not only give the credit to the pseudocapacitance effect of TT-Nb₂O₅, but also attribute to introduction of carbon. The homogeneous carbon-coated materials enhance the electrical conductivity, increase the electron transmission speed and alleviate particle crushing. This research not only offers a new method for preparing excellent electrode materials, but also provides a kind of excellent anode material with prospective application for LIBs.     

Energy and exergy analyses of a novel sulfur–iodine cycle assembled with HI–I2–H2O electrolysis for hydrogen production

A novel sulfur–iodine (SI or IS) cycle integrated with HI–I₂–H₂O electrolysis for hydrogen production was developed and thermodynamically analyzed in this work. HI–I₂–H₂O electrolysis was used to replace the conventional concentration, distillation, and decomposition processes of HI, so as to simplify the flowsheet of SI cycle. And then the new cycle was divided into Bunsen reaction, H₂SO₄ decomposition and HI–I₂–H₂O electrolysis sections. Through incorporating the user-defined module of HI–I₂–H₂O electrolysis with Aspen Plus, the cycle was simulated and 0.448 mol/h (10 L/h) of H₂ was produced. The overall energy and exergy efficiencies of the novel SI system were estimated to be 15.3–31.0% and 32.8%, respectively. Most exergy destruction occurred in the H₂SO₄ decomposer and condenser for H₂SO₄ decomposition and Bunsen reaction sections, which accounted for 93.0% and 63.4%, respectively. A high exergy efficiency of 92.4% for HI–I₂–H₂O electrolysis section with less exergy destruction was determined, mostly due to the transformation of the overall electricity in electrolytic cell to exergy. Appropriate internal heat exchange and waste heat recovery will favor improving the energy and exergy efficiencies.     

Remarkable enhancement of the photocatalytic activity of ZnO nanorod array by utilizing energy transfer between Eosin Y and Rose Bengal for visible light-driven hydrogen evolution

In this work, we suggested that an efficient ZnO-based photocatalyst can be prepared utilizing energy transfer among organic dyes for visible light-driven hydrogen evolution. Followed this idea, a photocatalytic system containing Eosin Y, Rose Bengal, ZnO nanorod array and Pt was fabricated. Meanwhile, photocatalytic H₂ evolution over the as-prepared photocatalytic system was explored. The results indicate that the visible photocatalytic activity of ZnO nanorod array can be obviously enhanced utilizing the energy transfer between Eosin Y and Rose Bengal. This photocatalytic system possesses high activity for visible light-driven H₂ evolution. A rate of H₂ evolution of approximate 0.52 L m^?2 h^?1 was achieved under optimal condition, which is 130% and 58% higher than those of the photocatalytic systems containing individual dye, respectively. The present results may reveal a new strategy for preparation of efficient visible photocatalyst.     

Lead halide perovskite nanowires stabilized by block copolymers for Langmuir-Blodgett assembly

The rapid development of solar cells based on lead halide perovskites (LHPs) has prompted very active research activities in other closely-related fields. Colloidal nanostructures of such materials display superior optoelectronic properties. Especially, one-dimensional (1D) LHPs nanowires show anisotropic optical properties when they are highly oriented. However, the ionic nature makes them very sensitive to external environment, limiting their large scale practical applications. Here, we introduce an amphiphilic block copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-P4VP), to chemically modify the surface of colloidal CsPbBr₃ nanowires. The resulting core-shell nanowires show enhanced photoluminescent emission and good colloidal stability against water. Taking advantage of the stability enhancement, we further applied a modified Langmuir-Blodgett technique to assemble monolayers of highly aligned nanowires, and studied their anisotropic optical properties.