DDJ型波状挡边带式输送机的使用及改进

介绍波状挡边带式输送机的结构特点、应用和在设计及应用中出现的问题 ,并对使用中出现的问题进行改造。     

河北某低品位锰银矿的选矿工艺研究

该矿石中银以多种分散状态与锰、铁矿物共生。不同流程结构的试验表明，“原矿破碎至２ｍｍ后分级磁选”工艺可获得含Ａｇ３０６ｇ／ｔ、Ｍｎ１４．１９％的混含精矿，Ａｇ、Ｍｎ回收率分别为８６．３６％、９３．６２％。     

CPR1000 核反应堆冷却泵电机的特殊性

为确保冷却泵驱动电机的安全和稳定性,对CPR1000型核反应堆冷却剂泵的安全保护设计进行研究。结合其主要组成及功能,阐述了驱动电机设计制造过程中的安全和稳定性能设计进行,分析了冷却泵材料、设计和工艺上的独特性。该研究使核电机组在各类复杂工况下运行的安全性更加有保障。     

落地式多绳摩擦提升罐笼更换方法

落地式多绳摩擦提升机更换罐笼工艺复杂,施工方法主要由固定东侧罐笼钢丝绳,摘西罐底尾绳并固定,将西罐与悬挂装置脱开,拉出西罐,新罐笼进入井口,新罐笼与悬挂装置、尾绳连接,新罐笼改由提升绞车牵引,解除东罐笼钢丝绳的约束,试运行等步骤组成。     

现场直剪试验在矿山边坡勘查中的应用

通过现场直剪试验与室内直剪试验方法成果进行比较，阐述了现场直剪试验方法的优点，对室内直剪试验存在的问题进行了探讨，分析说明现场直剪试验方法在矿山边坡勘查中的推广应用。饱和状态和天然状态下土的抗剪强度试验结果表明，孔隙水压力对边坡稳定产生较大影响。     

水平巷道烟流滚退发生条件的研究

为掌握烟流滚退的发生规律，采用理论分析的方法，对水平巷道火灾的烟流滚退现象进行了研究，导出了滚退发生的条件式，并建立了２个无量纲准则。     

浅阱中双组份玻色- 爱因斯坦凝聚体基态的稳定性研究

应用变分法研究了囚禁在有限深势阱中的双组份玻色-爱因斯坦凝聚体基态的稳定性,结果显示:在有限深势阱中有可能获取稳定的双组份凝聚体,但须满足囚禁原子数的临界条件和基态能量塌缩的临界条件.通过变分法计算还得到了波包的宽度、能量与相互作用系数之间的函数关系,并发现凝聚体之间的相互作用对其稳定性具有非常重要的作用.     

System level design and analysis of a fourth‐order continuous‐time delta‐sigma modulator using relaxed gain‐band‐width amplifiers

In this paper, based on mathematical approaches and behavioral modeling of internal blocks, an algorithm of designing a continuous‐time delta‐sigma modulator (CT ΔΣM) with aggressive noise shaping is discussed. Using proposed methods, the coefficients of modulator can be calculated directly while the finite gain‐band‐width of amplifiers and rise/fall time of digital‐to‐analog convertors (DACs) in feedback path are included in the transfer function of CT loop filter. To decrease the number of amplifiers, a unique resonator is proposed. Also, an extra feedback DAC is introduced to further reduction of gain‐band‐width requirement of last amplifier. To verify the effectiveness of proposed methods, a fourth‐order, single loop, CT ΔΣM that benefits proportional‐integrator element for compensation of excess‐loop‐delay is realized in system and behavioral circuit levels. It has a 4‐bit quantizer, over‐sampling‐ratio of 10, and out‐of‐band‐gain of 12 dB. The peaking in signal‐transfer‐function is alleviated using a feed‐forward capacitor along with proper choosing of rest coefficients. The designed modulator has 78‐dB signal‐to‐noise‐ratio; even the non‐ideal behaviors of amplifiers and DACs are involved in simulations. Independent to sampling frequency, the proposed methods can be applied to other topologies of CT ΔΣMs. Copyright © 2017 John Wiley & Sons, Ltd.     

Multi-walled carbon nanotubes-based magnetic solid-phase extraction for the determination of zearalenone and its derivatives in maize by ultra-high performance liquid chromatography-tandem mass spectrometry

A simple and rapid magnetic solid-phase extraction (M-SPE) procedure using multi-walled carbon nanotube-magnetic nanoparticles (MWCNT-MNPs) as sorbents was established for purification of zearalenone (ZEA), α-zearalenol (α-ZOL), β-zearalenol (β-ZOL), zearalanone (ZAN), α-zearalanol (α-ZAL) and β-zearalanol (β-ZAL) in maize. The main parameters affecting the clean-up efficiency were thoroughly investigated, and high purification efficiencies for all analytes were obtained. The resulting MWCNT-MNP-ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was validated for maize samples. The matrix effects were greatly minimized using the M-SPE approach, with signal suppression/enhancement values decreased from 69.9–127.6% to 92.1–103.8%. Consequently, complex matrix-matched calibration curves were not necessary and the calibrations constructed in acetonitrile could be applied for accurate quantification of the targeted mycotoxins in real samples. The average recoveries ranged from 75.8 to 104.1% and the inter- and intra-day precision values expressed as RSDs, were all lower than 14%. Limits of detection and quantification were in the range of 0.03–0.04 and 0.07–0.10 μg/kg, respectively. The analytical performance of the developed method was also successfully evaluated with maize samples, and this method was proved to be a powerful tool for monitoring ZEA and its derivatives in maize.     

Copper‐Catalyzed Domino Synthesis of Benzo[4,5]imidazo[1,2‐a]pyrimidin‐4(10H)‐ones using Cyanamide as a Building Block

An efficient and practical copper‐catalyzed domino synthesis of benzo[4,5]imidazo[1,2‐a]pyrimidin‐4(10H)‐ones has been developed. The protocol uses N‐(2‐halophenyl)‐3‐alkylpropiolamides and cyanamide as the starting materials, inexpensive copper(I) iodide and pipecolinic acid as the catalyst and ligand, and the corresponding products were obtained in moderate to good yields.

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