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.     

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。     

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.     

Levels of polybrominated diphenyl ethers in house dust in Central Poland

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in numerous products, from which they are emitted to the environment, including house dust. House dust is a source of human exposure to these compounds by ingestion. The aim of this article was to determine the levels of selected PBDEs in the house dust and indicate their potential sources of origin. PBDE congeners: BDE‐47, BDE‐99, BDE‐153 and BDE‐209, were analyzed in 129 samples. The geometric mean levels (and 95% CIs) of the aforementioned congeners amounted to 3.8 (3.1–4.7) ng/g, 4.5 (3.5–5.6) ng/g, 2.2 (2.1–2.4) ng/g and 345 (269–442) ng/g respectively. BDE‐209 was the dominant congener in the majority of tested samples. We found a statistically significant correlation between the concentrations of BDE‐47 and the computer operating time per day (r_s – 0.18) and the living area (r_s – 0.20). Statistically significant higher levels of BDE‐99 were found in homes where the floor was not replaced during the last 2 years.     

煤矿医院建筑空间与流线组织人性化研究

医院建设要“以病人为中心”,为病人营造优美、安静、舒适、方便的就医场所和环境.整体规划,分期建设,在建设过程中医院仍可正常运营.人流物流分开、医患分流、洁污分流、住院病人与门诊病人分开.住院、医技、门诊、急诊、后勤服务等功能分区明确,联系紧密,流线合理.建筑通道,各专业科室都有独立、安静的尽端,互不穿插；充分考虑自然通风和采光,一是节省运行费用,二是减少交叉感染.充分考虑公共用地,绿化等要求.     

Defining resilience for the US building industry

ABSTRACT

Initiatives to operationalize the concept of resilience in the building industry are rapidly emerging. The concept of resilience has introduced a way to explore solutions to some important problems in the building industry. However, much of the work that has taken place to date represents activities generally assigned to risk management, which is discussed as being inherently insufficient for sustaining the functions of the built environment under stresses. This commentary considers the opportunities and limitations for mainstreaming resilience into building industry processes and actors. Barriers include indeterminate analytical meaning, event and performance uncertainty, immature regulatory standards setting, and untested enterprise economics. Further, the multiple outcomes of recovery and the relationship between building recovery and adaptation are discussed and, along with economics of resilience investments, a research need highlighted. A simple heuristic is presented to illustrate the complement of resilience to risk management and advance the integration of resilience into existing industry workflows.     

项目导向教学模式在《SQL Server数据库》课程中的应用

文章以《SQL Server数据库》课程为例,以计算机应用专业面向岗位技能的需求,构建了11个项目,每个项目按照"项目概要-项目知识-项目分析-项目评价"的顺序展开教学,并以数据查询为例说明项目具体实施过程。