都市旅游：后奥运北京旅游产业的突破点

都市旅游是中国旅游发展的新潮流,是大城市发展到成熟和高水准阶段的产物。本文在对北京都市旅游发展潜力、发展现状进行分析的基础上,提出了今后北京都市旅游创新开发思路,就北京都市旅游产品整合开发策略进行了探讨。     

查慎行粤游诗的生态美

查慎行晚年游岭南,有诗《粤游集》二卷,查慎行的粤游诗体现了人与自然、人与人、人与社会、身与心、言与行、情与理的全面的生态和谐意识,对自然的诗意化观照和体验,对生命的认同和热爱,对社会和谐的追求和向往,对人生和现实的超越,是查慎行粤游诗最富有生态美意蕴的内核。从生态美学视野解读查慎行的粤游诗,对于理解清初朱彝尊、王士祯等诸大家的游粤诗创作有一定的借鉴意义。     

A Hybrid Genetic—GRASP Algorithm Using Lagrangean Relaxation for the Traveling Salesman Problem

Hybridization techniques are very effective for the solution of combinatorial optimization problems. This paper presents a genetic algorithm based on Expanding Neighborhood Search technique (Marinakis, Migdalas, and Pardalos, Computational Optimization and Applications, 2004) for the solution of the traveling salesman problem: The initial population of the algorithm is created not entirely at random but rather using a modified version of the Greedy Randomized Adaptive Search Procedure. Farther more a stopping criterion based on Lagrangean Relaxation is proposed. The combination of these different techniques produces high quality solutions. The proposed algorithm was tested on numerous benchmark problems from TSPLIB with very satisfactory results. Comparisons with the algorithms of the DIMACS Implementation Challenge are also presented.     

毫米波行波管电子光学系统计算机模拟

分析了毫米波行波管电子光学系统的基本特征和设计方法。提出了建立一体化电子光学模型,通过PIC模拟研究电子注静态传输特性的方法。对于改进和优化行波管电子光学系统设计,实现“设计制管一次成功”具有一定的参考价值。     

带杠杆效应的无穷纯跳跃Levy过程期权定价

讨论了带有实时交通信息的动态网络车辆路径派送问题。问题包含重复性拥堵和非重复性拥堵两种情形。用重复性拥堵下的交通信息以安排初始路径,通过采用遗传算法求解时变车辆调度问题。车辆在行驶过程中需要根据接收到的实时交通信息调整路线。提出在关键点更新路线的机制,并采用Dynasearch算法求解一类特殊的旅行商问题调整路线。通过对SiouxFalls网络进行数值模拟分析,结果表明新策略能在较短时间内改进其他策略,且随着网络动态性增加其优越性更加明显。     

A meta-synthesis of the perspectives and experiences of healthcare professionals on the humanisation of childbirth using a meta-ethnographic approach

ProblemThe humanisation of childbirth has been identified as a practice of care focusing on the physical, psychological, and emotional wellbeing of women. Healthcare professionals (HCPs) are expected to understand and embed humanised practice when supporting women in childbirth.AimThe aim of this paper is to present a meta-synthesis of the experiences and perspectives of HCPs who undertake care for women at the time of birth regarding the humanisation of childbirth.MethodsA systematic search of the electronic databases CINAHL, Medline, PsycINFO, and SocINDEX were conducted in July 2020. Qualitative studies exploring HCPs’ experiences and perspectives of humanisation in childbirth were eligible. Studies were synthesised using a meta-ethnographic approach.FindingsFourteen studies involving 197 participants were included. Two themes were identified: ‘Women at the centre’ and ‘Professional dissonance’. Two line of argument synthesis were identified: ‘invisible boundaries’ and ‘unconscious undermining’.DiscussionHCPs recognised that women required positive interactions which met both their emotional and physical needs. Human touch supported bonding between HCPs and women. HCPs understood humanisation as the reduction of unnecessary intervention and/or technology but had difficulties enacting this and often used disempowering language when discussing women’s choices. The management of pain and the presence of a companion were considered important by HCPs.ConclusionThis synthesis revealed that HCPs do understand the humanisation of childbirth but have difficulties in enacting it in practice. Women classified as high risk were identified as having specific needs such as increased emotional support. Further research is required for women classified as high risk who may require technology and/or interventions to maintain a safe birth.     

邯郸市居民出行特征分析

利用邯郸市的交通调查资料,对市区居民出行的基本特征进行了分析,探讨了邯郸市居民出行的对策,提出了发展城市公共交通是解决居民出行、改善交通环境和空气质量的主要途径。