反渗透淡化水调质稳定性及健康性实验研究

反渗透淡化水因矿物质含量低、稳定性差,需进行调质以改善水质。通过研究调质后水体碳酸钙沉淀势CCPP、Ryznar稳定指数R.S.I.、拉森指数LR、氧化还原电位ORP等指标与调质剂(NaHCO₃、CaCl₂)投加量间的关系,为反渗透淡化水调质剂投加剂量提供依据。研究表明：NaHCO₃为50 ~90 mg·L^-1时,随着投加量的增加,R.S.I.降低（趋近于6.0~7.0）,水质稳定性改善,NaHCO₃为90~110 mg·L^-1时,随着投加量的增加,R.S.I.升高（偏离了6.0~7.0）,水质稳定性变差;随着NaHCO₃投加量的增加,CCPP降低,水质由沉淀倾向变为腐蚀倾向,当NaHCO₃投加量达到70 mg·L^-1时,CCPP趋于稳定,水质稳定;随着NaHCO₃投加量的继续增加,LR降低,水质稳定性改善,而ORP降低,当NaHCO₃投加量达到90 mg·L^-1时,ORP趋于平缓。建议NaHCO₃投加量为90 mg·L^-1。随着Ca²⁺投加量的增加,R.S.I.、CCPP降低,水体稳定性变差;CaCl₂投加量增加,LR增加,水质稳定性变差,ORP增大,水质健康性变差。建议CaCl₂投加量为20 mg·L^-1。     

家庭医生制服务可持续发展策略、措施及思考

采用文献分析、专家咨询、试点研究尝试等方法,构建了以家庭医生、家庭健康协管员、社区卫生服务机构为主线的家庭医生制服务模式基本框架体系和以家庭健康诊断为基础、家庭医生培训与认定为保障、家庭健康管理为重点的运行机制。提出家庭医生培养、认定以及配套政策是家庭医生制服务可持续发展的关键点。     

A branch and bound algorithm for determining locations of long-term care facilities

This paper focuses on the problem of determining locations for long-term care facilities with the objective of balancing the numbers of patients assigned to the facilities. We present a branch and bound algorithm by developing dominance properties, a lower bounding scheme and a heuristic algorithm for obtaining an upper bound for the problem. For evaluation of the suggested branch and bound algorithm, computational experiments are performed on a number of test problems. Results of the experiments show that the suggested algorithm gives optimal solutions of problems of practical sizes in a reasonable amount of computation time.     

Workforce staffing and scheduling: Hospital nursing specific models

Decisions relating to hospital nurse staffing and scheduling are among the most important decisions made in hospitals today. Staffing and scheduling choices must be made which will result in timely and high-quality care to patients. These choices are complicated by the requirement for round-the-clock staffing in many hospital nursing units, a severe nursing shortage, and an outcry from many quarters to cut costs of health care. In general, patients today are kept in hospitals only if they are in need of highly skilled nursing care. In this paper we present a review of some of the issues in health care currently influencing the hospital nurse staffing and scheduling environment. In addition, we review the literature that illustrates nurse manager's concerns, and approaches taken in the past by operations researchers to address those concerns. We present some data from a recent study of nurse managers in 31 hospitals that illustrates the complexity of the issues. We conclude with a discussion of future research directions in hospital nurse staffing and scheduling.     

In situ measurements of radon levels in water and soil and exhalation rate in areas of Malwa belt of Punjab (India)

Radon concentration levels in water and soil gas from 36 locations pertaining to some areas of Malwa region of Punjab have been measured on an in situ basis using a continuous active radon detector (AlphaGuard, Model – PQ 2000 PRO, Genitron instruments, Germany). Exhalation rate measurements have also been carried out at these places, using a closed-circuit technique. The radon concentrations in soil and water varied from 1.9 to 16.4 kBq m^?3 and 5.01 to 11.6 kBq m^?3, respectively. The exhalation rate (E _Rn) ranged between 7.48 and 35.88 mBq m^?2 s^?1 with an average value of 18.17 mBq m^?2 s^?1. Annual dose rates have been calculated for water radon concentrations. The minimum to maximum values of dose rates were found to be 13.42–31.08 μSv y^?1. The recorded values of radon concentration in water are within the safe limit of 11 Bq l^?1 recommended by the US Environment Protection Agency [National Research Council, Risk Assessment of Radon in Drinking Water (Academy Press, Washington, DC, USA, 1999)]. All measurements were made in similar climatic and environmental conditions to ensure minimal variations in meteorological parameters. An intermediate correlation coefficient (0.5) was observed between radon exhalation rates and soil gas values.     

高温超导电缆节能环保与经济可行性分析

人们对电能需求的持续增长,促使电网输电密度和输电容量逐渐增大,传统的输电技术将遇到越来越多的问题,这个矛盾在大城市中显得尤为突出。高温超导电缆具有传输容量大和功率密度高等优势,是解决这些问题和满足未来大容量电力传输的重要技术之一。文中在介绍高温超导电缆的基本结构和发展现状的基础上,研究其在节能环保和经济方面的优势;并以北京为例,分析了高温超导电缆在大城市中应用的可行性。     

分布式光纤传感器在预应力结构健康监测中的应用研究

介绍了国内外分布式光纤传感器应用于桥梁等大型预应力混凝土结构进行安全监测的现状,讨论了光纤传感器在大型预应力等结构健康监测应用中的发展前景。     

Using the tabu search method for the distribution of supplies in a hospital

Two supply delivery systems in a hospital are compared. In order to evaluate the number of carriers required by the new system, an operational research model has been developed and solved by the tabu search method. The results indicate that the new system is better except on weekend days.This work has been achieved while the second author was visiting the Université de Montréal.     

Location of Preventive Health Care Facilities

This paper is focused on the problem of locating preventive health care facilities. The aim is to maximize participation to prevention programs. We assume that distance is a major determinant of participation and people would go to the closest facility for preventive health care. Each facility is required to have more than a predetermined number of clients because of the direct relationship between volume and quality of preventive services. We provide a mathematical formulation and present alternative solution approaches for this new location problem. We report on computational performance of the proposed methods in locating public health centers in Fulton County, Georgia and mammography screening centers in Montreal, Quebec.     

Calibration and numerical simulation of Nanoparticle Surface Area Monitor (TSI Model 3550 NSAM)

TSI Nanoparticle Surface Area Monitor (NSAM) Model 3550 has been developed to measure the nanoparticle surface area deposited in different regions of the human lung. It makes use of an adjustable ion trap voltage to match the total surface area of particles, which are below 100 nm, deposited in tracheobronchial (TB) or alveolar (A) regions of the human lung. In this paper, calibration factors of NSAM were experimentally determined for particles of different materials. Tests were performed using monodisperse (Ag agglomerates and NaCl, 7–100 nm) and polydisperse particles (Ag agglomerates, number count mean diameter below 50 nm). Experimental data show that the currents in NSAM have a linear relation with a function of the total deposited nanoparticle surface area for the different compartments of the lung. No significant dependency of the calibration factors on particle materials and morphology was observed. Monodisperse nanoparticles in the size range where the response function is in the desirable range can be used for calibration. Calibration factors of monodisperse and polydisperse Ag particle agglomerates are in good agreement with each other, which indicates that polydisperse nanoparticles can be used to determine calibration factors. Using a CFD computer code (Fluent) numerical simulations of fluid flow and particle trajectories inside NSAM were performed to estimate response function of NSAM for different ion trap voltages. The numerical simulation results agreed well with experimental results.