3OCrMnSiA钢燃烧室的热处理工艺试验

为解决30CrMnSiA钢燃烧室旋压成形件等温淬火后硬度偏高时,可否采用回火的方法降低硬度的意见分歧,对这种燃烧室作了等温淬火、油淬＋回火、等温淬火＋回火3种不同热处理状态下材料机械性能的对比试验.试验结果表明：这种材料的燃烧室在等温淬火后,若硬度偏高不合格,采用回火的方法降低硬度后,其材料的冲击韧性将会大幅度下降,将远低于有关材料标准的要求.因此,对于安全系数不太高的30CrMnSiA钢燃烧室,不能允许以回火的方法来降低硬度,而应采用其他的工艺方法来降低硬度.而且不能笼统地认为燃烧室材料的抗拉强度和伸长率都合格,其冲击韧性也一定会合格.     

开发商决策阶段风险分析

目前随着全国各地的城市建设、房地产开发的轰轰烈烈的发展,业主(开发商)将大部分资金投入到上面,这里面有自有资金,还有银行贷款,如此巨额的投资对房地产商来说存在着很大的风险,现就将投资过程中的外部环境风险、可行性研究风险做以下分析。     

机械臂视觉伺服路径规划研究进展

视觉伺服控制是机械臂完成各种复杂作业任务的有效手段,而机械臂在动态非结构环境下自主作业的路径规划方法是视觉伺服控制领域的难点和关键.分析了动态非结构环境下视觉伺服路径规划中存在的两类约束及其处理方法,介绍并评述了国内外在机械臂视觉伺服控制中路径规划方面的相关研究进展,讨论并分析了不同路径规划方法在收敛性和稳定性等方面存在的不足,对未来的研究方向进行了展望.     

Enantioseparations in Achiral Environments and Chromatographic Systems

Since the very first resolution of racemic tartaric acid by Pasteur, the importance of resolution and methodology has been on a path of continuous understanding and expansion. The science and chemistry of achieving such targets has changed a lot. The advent of chromatography changed the direction by involving synthetic, semisynthetic, or naturally occurring chiral materials for a direct approach to resolution, where rapid and reversible association occurs to form diastereomers with different stabilities and partition coefficients responsible for overall enantioseparation. It has now reached a stage where the separation of excess enantiomers from nonracemic mixtures has been achieved in a totally achiral environment, which does not appear to be in line with the prevalent concepts of basic stereochemistry. Caution should be exercised when enantiomerically enriched mixtures – obtained by enantioselective synthesis – are chromatographed for purification in preparative organic synthesis.     

类铀矿岩材料制备及氡扩散系数测定的实验研究

扩散过程是主导氡在铀矿岩中运移与析出的主要方式。铀矿原岩辐射较大且取样困难,不利于开展有关室内实验。为了解决以上问题,依据相似理论,以某花岗岩为原型,选取石英砂、铀尾砂、水泥、精铁粉和微硅粉等为原材料,制备了3种不同材料配比的圆柱形类铀矿岩试样,并测定了原型和试样的物理力学参数;然后采用密闭腔体法测量了原型和试样在不同包裹方式下的累积氡浓度,推导氡的扩散性能参数的计算公式,通过计算获得了原型和试样的氡扩散长度和扩散系数。实验结果表明:花岗岩原型与所制备的类铀矿岩的颗粒密度、抗压强度、抗拉强度、内聚力和内摩擦角相似比的均值分别为1.09∶1、3.93∶1、4.28∶1、3.47∶1和1.00∶1;花岗岩原型的扩散系数为0.146×10^-6m²·s^-1,类铀矿岩的扩散系数介于0.114×10^-6～0.594×10^-6m²·s^-1之间,两者的相似比介于0.25∶1～1.28∶1之间。研究认为所制备的试样3在一定程度上可用来模拟花岗岩型铀矿岩,以满足室内实验的需求。     

湿硫化氢环境中设备应力腐蚀分析及控制

文章阐述了硫化氢应力腐蚀机理,分析和探讨了在湿硫化氢环境中影响应力腐蚀的相关因素,并针对这些影响因素提出了相应的防止硫化氢应力腐蚀的技术和工艺措施。     

浅谈住宅小区电气规划设计要点

本文阐述了住宅区的低压配电干线合理规划的原则和要点,建议把室外管线综合的工作放在建筑方案设计初期.并介绍了住宅区的电气规划的工作内容及常用方法,从而解决了施工后期经常出现的管线布置困难的问题.     

绿色科技在国内公共建筑中的应用

通过研究国内当前基于绿色视角的建筑设计实践，分析绿色建设的策略，从不同角度的案例来总结绿色建筑设计思想与策略，解析国内绿色建筑的建设方向与趋势，进一步深化对绿色建筑的认识。     

Patch-Levy-based initialization algorithm for Bees Algorithm

The Bees Algorithm (BA) is a population-based metaheuristic algorithm inspired by the foraging behavior of honeybees. This algorithm has been successfully used as an optimization tool in combinatorial and functional optimization fields. In addition, its behavior very closely mimics the actual behavior that occurs in nature, and it is very simple and easy to implement. However, its convergence speed to the optimal solution still needs further improvement and it also needs a mechanism to obviate getting trapped in local optima. In this paper, a novel initialization algorithm based on the patch concept and Levy flight distribution is proposed to initialize the population of bees in BA. Consequently, we incorporate this initialization procedure into a proposed enhanced BA variant. The proposed variant is more natural than conventional variants of BA. It mimics the patch environment in nature and Levy flight, which is believed to characterize the foraging patterns of bees in nature. The results of experiments conducted on several widely used high-dimensional benchmarks indicate that our proposed enhanced BA variant significantly outperforms other BA variants and state-of-the-art variants of the Artificial Bee Colony (ABC) algorithm in terms of solution quality, convergence speed, and success rate. In addition, the results of experimental analyses conducted indicate that our proposed enhanced BA is very stable, has the ability to deal with differences in search ranges, and rapidly converges without getting stuck in local optima.     

Anticipation and flexibility in dynamic scheduling

Many real-world optimization problems change over time and require frequent re-optimization. We suggest that in such environments, an optimization algorithm should reflect the problem's dynamics and explicitly take into account that changes to the current solution are to be expected. We claim that this can be achieved by having the optimization algorithm search for solutions that are not only good, but also flexible, i.e. easily adjustable if necessary in the case of problem changes. For the example of a job-shop with jobs arriving non-deterministically over time, we demonstrate that avoiding early idle times increases flexibility, and thus that the incorporation of an early idle time penalty as secondary objective into the scheduling algorithm can greatly enhance the overall system performance.