酸催化二甘醇脱水环化反应研究

以硫酸、磷钨酸、ZRP-5分子筛为催化剂,研究了二甘醇(DEG)脱水环化的反应规律。结果表明,DEG发生分子内脱水环化反应,生成1,4-二氧六环(DOX),DEG分子间脱水不仅可以生成四甘醇、六甘醇等,同时可生成三甘醇、五甘醇等一系列的多甘醇(PEG)。不仅DEG可以脱水环化生成DOX,在反应中生成的PEG也同样可以进行生成DOX的反应。对于二甘醇(DEG)脱水环化反应,硫酸是性能优良的催化剂,反应可以在较低的温度下进行,馏出产物中DOX选择性大于95％。     

Evaluating Particle Deposition in the Artificial Groundwater Recharge Process by Physical and CT Imaging Experiments

Particle clogging in the artificial groundwater recharge process is one of the main factors influencing the artificial groundwater recharge efficiency, and particle deposition is the microscopic mechanism of the occurrence and development of particle clogging. Particle deposition in porous media changes the pore structure. The computed tomography (CT) scanning technique is a nondestructive testing method and determines the spatial distribution of pores in porous media. This study combines physical and CT scanning experiments to identify the change process of the pore structure in the artificial groundwater recharge process and compares the pore changes during recharge experiments between two columns containing different media. Porous media changes are observed with the CT scanning technique. The fractal theory is applied in the analysis of CT scan images and physical experiment results. The results of this study indicate that particle deposition can be examined by using CT scan images to obtain pore-related parameters, the internal pore structure of porous media determined through CT scan images can be applied in numerical simulation, and a mathematical model for particle deposition calculation in porous media is established. Compared to the physical experiment measurements, the spatial particle deposition information acquired with the CT scanning technique exhibits a higher accuracy and contains much more relevant data. Not only does this research reveal more clearly the particle clogging mechanism which is based on particle deposition, but also characterize, simulate and predict more accurately the development tendency of particle clogging during artificial groundwater recharge.

     

建安工程中的索赔问题

施工索赔是我国建筑业与国际接轨出现的新问题,讨论存在的问题及解决的办法。     

Modeling and experiment of surface error for large-aperture aspheric SiC mirror based on residual height and wheel wear

Shaped metal deposition method using gas tungsten arc welding is a novel manufacturing technology that can be used for fabricating solid dense parts in layered manufacturing. This paper reports for the first time using the pulsed current shaped metal deposition technique for fabricating components using cold wire of AISI 308LSi stainless steel. The aim of this work was to investigate and compare the effect of pulse frequency and other deposition process parameters on the morphology aspects and microstructure characteristics of the manufactured components using pulsed and continuous current processes. The obtained results reveal that the structure of the deposited specimens produced via pulsed arc current is generally having finer grains, high residual ferrite, and absence of columnar grains. Pulse frequency and current ratio have a significant influence on the surface morphology and microstructure of the manufactured parts. Good metallurgical bonding with no sensitization effects can be seen in all tested specimens. The presented additive layered manufacturing method can be recommended for near net-shaped processing of austenitic stainless steel components, and it can be used as an alternative manufacturing method for fabricating metal components with free defects, higher corrosion resistance, and superior mechanical properties.     

Experimental study of quantum simulation for quantum chemistry with a nuclear magnetic resonance simulator

Quantum computers have been proved to be able to mimic quantum systems efficiently in polynomial time. Quantum chemistry problems, such as static molecular energy calculations and dynamical chemical reaction simulations, become very intractable on classical computers with scaling up of the system. Therefore, quantum simulation is a feasible and effective approach to tackle quantum chemistry problems. Proof-of-principle experiments have been implemented on the calculation of the hydrogen molecular energies and one-dimensional chemical isomerization reaction dynamics using nuclear magnetic resonance systems. We conclude that quantum simulation will surpass classical computers for quantum chemistry in the near future.     

简述提高充填接顶效果的控制措施

充填接顶是充填工作的重要内容,关系到充填体的承载效果,本文深入分析了导致充填不能接顶的各种原因,并提出了相应的解决方案和改进措施,为解决矿山充填体不接顶问题,改善作业条件提供了有效途径。     

电火花修整金属基圆弧砂轮表面形貌的实验研究

金属基金刚石圆弧砂轮因其高效的加工性能而被普遍应用于大口径SiC陶瓷的加工中,但由于磨削过程中损耗量较大限制了其更广泛的应用。为了减少砂轮磨削时的损耗量,本实验提出采用电火花修整金属基圆弧砂轮的方法,针对50~63 μm粒度金属砂轮进行电压、电流、脉冲频率等单因素试验;通过超景深显微镜观察不同电参数对于砂轮表面形貌的影响并分析表面蚀除量与电参数幅值的相互关系。实验结果表明:为获得较好的砂轮表面修整质量,应选用电压为60 V、脉冲频率为25 kHz、多通道电流的电参数值。      

一种小型化水声信号调制发射系统

为了满足小型化水下工作平台远距离通信的需求,从发射功率和通信体制两方面出发,提出了一种小型化水声信号调制发射系统的设计方案.设计了发射信号结构,以直接序列扩频通信体制为基础,采用结合移相脉冲宽度调制技术生成发射信号,进行了调制算法的仿真.应用体积小、效率高的D类功率放大器,设计了布局合理的系统结构和稳定可靠的硬件电路,优化发射机与换能器之间的匹配滤波网络,实现了小型化系统.系统在海试中完成了浅海、远距离、低误码率通信.系统工作稳定,有一定的工程应用价值.     

南水北调工程征地移民验收管理制度创新

加强对南水北调工程征地移民工作质量评价和验收工作的制度化和规范化管理。提高对征地移民验收工作的管理水平,保护移民的合法权益,维护投资人的利益,山东省出台了《山东南水北调工程征地移民验收管理暂行办法》,从分级管理的角度,结合南水北调工程建设征地补偿和移民安置的特点,对征地移民验收管理制度进行创新。     

一个特殊的奥运场馆——射击馆的资格赛馆暖通空调设计

介绍了射击资格赛馆的特殊性以及针对其特殊性所作的设计.针对1层两个比赛厅北墙敞开的特点,采用全空气空调系统、排风从敞开空间自然排出方案;针对空调机房距4个比赛厅仅一墙或一板之隔的特点,空调机隔振采用浮筑楼板加减振台板、隔声采用双墙中间夹隔声材料层的方案;针对奥运会后观众区改作他用、运动区继续作集训使用的特点,观众区和运动区各有一套空调系统,运动区另设风机盘管和地板供暖;针对步枪、手枪射击时产生弹药味的特点,采用吊顶设通风格栅、高窗设电动开启的自然通风方案.