三集一体热泵空调在某工程中的设计应用

介绍了三集一体热泵空调系统的工作原理,它与常规的泳池空调系统相比,具有节能和运行管理方便的优点;并以无锡芙蓉山庄会所室内游泳池的空调系统设计为例,介绍了设备的选型计算过程。     

Pollution level, phase distribution and source analysis of polycyclic aromatic hydrocarbons in residential air in Hangzhou, China

A survey of polycyclic aromatic hydrocarbons (PAHs) in residential air in Hangzhou, China, was carried out. Air samples were collected from indoor and outdoor environments during both summer and winter and analyzed for the level of 16 PAHs. The results showed total PAH contents ranging from 0.425 to 36.2 microg/m(3) with highest concentrations in the kitchen areas generally. Particulate PAHs were predominantly absorbed on PM(2.5) with proportion of 59-97% to total particulate phase, followed by PM(2.5-10) (3-24%) and PM(>10) (0-17%). PAH concentrations in indoor air of smoking residences tended to be higher than those of nonsmoking residences. Outdoor environment, Chinese conventional cooking practice, mothball emission and unknown source accounted for -10.5%, 32.8%, 71.5% and 6.2% of total PAHs in indoor air of nonsmoking residences, respectively. Outdoor environment was the fate for indoor PAHs in general, and consumed 10.5% of total PAHs. Finally, health risks associated with the inhalation of PAHs were assessed, and the results indicated that health-based guideline levels for lung cancer risk were exceeded. The largest contribution to total health risks in summer and winter was NA (72.9%) and BaP (45.2%), respectively.     

Assessing the effect of initial vapor-phase concentrations on inhalation risks of disinfection-by-products (DBP) in multi-use shower facilities

Inhalation during showering activities is a major pathway for exposure to volatile disinfection-by-products (DBPs). Disinfection-by-products such as trihalomethanes (THMs) and haloacetic acids (HAAs) have been shown to significantly increase cancer risks and can also pose other health hazards. In multi-family residences and common-shower facilities located in dormitories and gymnasiums, the time-lag between showers is likely to be short and the exposure to vapor-phase DBPs may be significantly increased due to residual concentrations from earlier showering activities. Current models do not consider the impacts of the initial vapor-phase concentration on health risks to be significant. The hypothesis that non-zero initial DBP vapor-phase concentrations lead to higher exposure and health risks was evaluated here using data from the City of Corpus Christi, TX at two levels of input parameter uncertainty. The inhalation risks and hazards were found to be over 1.5 times greater for subsequent showers compared to the initial shower of the day. For non-zero initial air concentrations and triangular distribution of input parameters, the model was found to be most sensitive to the initial air concentrations, highlighting the impact of initial conditions on cumulative daily intake (CDI) and subsequently on cancer risks and hazard indices. Increasing the time-gap between showers and improving ventilation are viable solutions to contend with the increased risk. It is recommended that the effects of initial air concentrations be incorporated in future risk assessments focusing on multi-family residences in older and poor neighborhoods where single shower dwellings are more common.     

Indoor radon concentration and its possible dependence on ventilation rate and flooring type

The results of radon concentration measurements carried out in dwellings with natural ventilation for 1 y in Bangalore are reported. Measurements, covering three sessions of the day (morning, afternoon, night) were performed two times in a month for 1 y at a fixed place of each dwelling at a height of 1 m above the ground surface in selected dwellings. The low-level radon detection system (LLRDS), an active method, was used for the estimation of radon concentration. The measurements were aimed to understand the diurnal variation and the effect of ventilation rate and flooring type on indoor radon concentration. The geometric mean (± geometric standard deviation) of indoor radon concentration from about 500 measurements carried out in 20 dwellings is found to be 25.4 ± 1.54 Bq m?3. The morning, afternoon and night averages were found to be 42.6 ± 2.05, 15.3 ± 2.18 and 28.5 ± 2.2 Bq m?3, respectively. The approximate natural ventilation rates of the dwellings were calculated using the PHPAIDA--the on-line natural ventilation, mixed mode and air infiltration rate calculation algorithm and their effects on indoor radon concentrations were studied. The inhalation dose and the lung cancer risk due to indoor radon exposure were found to be 0.66 mSv y?1 and 11.9 per 10? persons, respectively. The gamma exposure rate was also measured in all the dwellings and its correlation with the inhalation dose rate was studied.     

On uncertainty in remediation analysis: variance propagation from subsurface transport to exposure modeling

Addressing long-term potential human exposures to, and health risks from contaminants in the subsurface environment requires the use of models. Because these models must project contaminant behavior into the future, and make use of highly variable landscape properties, there is uncertainty associated with predictions of long-term exposure. Many parameters used in both subsurface contaminant transport simulation and health risk assessment have variance owing to uncertainty and/or variability. These parameters are best represented by ranges or probability distributions rather than single values. Based on a case study with information from an actual site contaminated with trichloroethylene (TCE), we demonstrate the propagation of variance in the simulation of risk using a complex subsurface contaminant transport simulation model integrated with a multi-pathway human health risk model. Ranges of subsurface contaminant concentrations are calculated with the subsurface transport simulator T2VOC (using the associated code ITOUGH2 for uncertainty analysis) for a three-dimensional system in which TCE migrates in both the vadose and saturated zones over extended distances and time scales. The subsurface TCE concentration distributions are passed to CalTOX, a multimedia, multi-pathway exposure model, which is used to calculate risk through multiple exposure pathways based on inhalation, ingestion and dermal contact. Monte Carlo and linear methods are used for the propagation of uncertainty owing to parameter variance. We demonstrate how rank correlation can be used to evaluate contributions to overall uncertainty from each model system. In this sample TCE case study, we find that although exposure model uncertainties are significant, subsurface transport uncertainties are dominant.     

A survey of modeling techniques for consequence analysis of accidental chemical releases to the atmosphere

This paper surveys techniques for estimating the consequences of accidental chemical releases to the atmosphere. The first section is devoted to a discussion of the characterization of gas, liquid and two-phase releases. In addition to the mass release rate, parameters such as phase composition, density and velocity are shown to be of critical importance in the subsequent dispersion of the release. Emissions due to boiling and evaporation from liquid spill pools are also treated. The second part of the paper describes the techniques for calculating the spatial and temporal variation of chemical concentrations due to jet and heavy gas dispersion. Methods are also presented for estimating the damage resulting from the ignition of a flammable plume or liquid spill pool. Finally, the paper deals with model prediction uncertainty and its impact upon the process of emergency response planning.     

High background radiation areas: the case of Villar de la Yegua village (Spain)

The starting point of the Spanish experience in the study of High Background Radiation Areas is the development of a nationwide indoor radon survey carried out in 1988. This campaign, belonging to the first Spanish Radon Framework, consisted of approximately 2000 indoor radon measurements which represented a valuable basis to face rigorously the radon issue in Spain. Together but indepently from this survey, since 1991 the Spanish Nuclear Safety Council, the National Uranium Company and several Universities have developed the so-called MARNA project with the aim of estimating potential radon emission from external gamma dose rates, radium concentrations in soil and geological parameters. During the last decade, several regional surveys have also been conducted to determine exposure to natural sources of radiation in different highly populated background radiation areas. Among them, the surroundings of the village of Villar de la Yegua Town, located in the western province of Salamanca, is the most important area of Spain from a radiological point of view, with the highest indoor radon concentrations, of up to 15,000 Bq m(-3) being found there. Until now, the main result of the study in this area showed a geometric mean radon concentration of 818 Bq m(-3), which is 18 times higher than the national average. In this article, the results of the last survey, carried out in Villar de la Yegua during 2004 are summarised. A geometric mean radon concentration of 1356 Bq m(-3) was found. Dose estimation coming from radon inhalation is also shown.     

室内游泳池暖通设计的几点体会

分析了室内游泳馆池厅的空气状态参数的确定和通风量的计算方法．介绍了防止围护结构结露的措施,并对池区与观众区空调系统划分、气流组织以及提高人员热舒适感等问题进行了探讨。     

An examination of exposure control and content balancing restrictions on item selection in CATs using the partial credit model

The purpose of the present investigation was to systematically examine the effectiveness of the Sympson-Hetter technique and rotated content balancing relative to no exposure control and no content rotation conditions in a computerized adaptive testing system (CAT) based on the partial credit model. A series of simulated fixed and variable length CATs were run using two data sets generated to multiple content areas for three sizes of item pools. The 2 (exposure control) X 2 (content rotation) X 2 (test length) X 3 (item pool size) X 2 (data sets) yielded a total of 48 conditions. Results show that while both procedures can be used with no deleterious effect on measurement precision, the gains in exposure control, pool utilization, and item overlap appear quite modest. Difficulties involved with setting the exposure control parameters in small item pools make questionable the utility of the Sympson-Hetter technique with similar item pools.     

Use of computer dynamic simulation for indoor exposure assessment based on chronogram incident as air pollution source characterization

Determination of the level of exposure due to a chemical incident is crucial for the assessment of public health risks and environmental impact. This kind of information is also useful for the subsequent legal responsibilities. If the air contaminant concentrations are not quantified during the incident, then its air concentration may fall below detectable levels shortly after the incident has passed. In case of smelly compounds, usually the incident chronogram indicates the time when the smell was detected and when the smell was gone. Unfortunately, an objective and analytical measure of odour is impossible. The present study shows that it is possible to computer simulate the concentration evolution in time for a defined indoor scenario. Comparing the odour detection in the chronogram with the computer simulations, it is feasible to determine the maximum gas contaminant exposure during the incident and its evolution in time. Once the pollution source indoor concentration is characterized, considering the overall air renewal time and a plume model, the effects on the environment around the building can be estimated.     

无锡蠡湖项目室内游泳池空调方案对比及分析

介绍了室内游泳池空调两方案对比及经济分析.通过模拟计算,发现采用除湿热泵机组节能并节约运行费用,但其初投资相对较高,静态回收周期长.     

Passive elastic mechanism to mimic fish-muscle action in anguilliform swimming

Swimmers in nature use body undulations to generate propulsive and manoeuvring forces. The anguilliform kinematics is driven by muscular actions all along the body, involving a complex temporal and spatial coordination of all the local actuations. Such swimming kinematics can be reproduced artificially, in a simpler way, by using the elasticity of the body passively. Here, we present experiments on self-propelled elastic swimmers at a free surface in the inertial regime. By addressing the fluid–structure interaction problem of anguilliform swimming, we show that our artificial swimmers are well described by coupling a beam theory with the potential flow model of Lighthill. In particular, we show that the propagative nature of the elastic wave producing the propulsive force is strongly dependent on the dissipation of energy along the body of the swimmer.     

Quantitative risk analysis for toxic chemicals in the environment

An overview and basic framework is presented for quantification of human health risks associated with toxic chemicals in the environment. The presentation is designed for program managers who require an introduction to the principles of risk analysis and an understanding of the current state-of-the-art. The basic terminology is explained, the methodological components are reviewed, and a series of procedures is discussed for estimating ambient concentrations, effect potency, and human exposure and risk levels for a chemical substance. Practical considerations are discussed, including the uncertainties introduced by data gaps and modelling assumptions. Finally, a simple numerical illustration of the calculation procedures is presented.     

Speed limits on swimming of fishes and cetaceans.

Physical limits on swimming speed of lunate tail propelled aquatic animals are proposed. A hydrodynamic analysis, applying experimental data wherever possible, is used to show that small swimmers (roughly less than a metre long) are limited by the available power, while larger swimmers at a few metres below the water surface are limited by cavitation. Depending on the caudal fin cross-section, 10-15 m s(-1) is shown to be the maximum cavitation-free velocity for all swimmers at a shallow depth.     

Effects of Surface-Active Elements Sulfur on Flow Patterns of Welding Pool

A 3D mathematical model is developed to calculate the temperature and velocity distributions in a moving gas tungsten arc (GTA) welding pool with different sulfur concentrations. It has been shown that, the weld penetration increases sharply with increasing sulfur content. When sulfur content increases beyond 80 ×10-6, the increase in sulfur content does not have an appreciable difference on the welding pool size and shape, and the depth/width remains constant. Sulfur changes the temperature dependence of surface tension coefficient from a negative value to a positive value and causes significant changes on flow patterns. The increase in soluble sulfur content and the decrease at free surface temperature can extend the region of positive surface tension coefficient. As sulfur content exceeds 125×10-6, the sign of surface tension coefficient is positive. Depending upon the sulfur concentrations, three, one or two vortexes that have different positions, strength and directions may be found in the welding     

Controlled Propulsion of Two‐Dimensional Microswimmers in a Precessing Magnetic Field

Magnetically actuated micro‐/nanoswimmers can potentially be used in noninvasive biomedical applications, such as targeted drug delivery and micromanipulation. Herein, two‐dimensional (2D) rigid ferromagnetic microstructures are shown to be capable of propelling themselves in three dimensions at low Reynolds numbers in a precessing field. Importantly, the above propulsion relies neither on soft structure deformation nor on the geometrical chirality of swimmers, but is rather driven by the dynamic chirality generated by field precession, which allows an almost unconstrained choice of materials and fabrication methods. Therefore, the swimming performance is systematically investigated as a function of precession angle and geometric design. One disadvantage of the described propulsion method is that the fabricated 2D swimmers are achiral, which means that the forward/backward swimming direction cannot be controlled. However, it has been found that asymmetric 2D swimmers always propel themselves toward their longer arm, which implies that dynamic chirality can be constrained to be either right‐handed or left‐handed by permanent magnetization. Thus, the simplicity of fabrication and possibility of dynamic chirality control make the developed method ideal for applications and fundamental studies that require a large number of swimmers.     

Levels and health risks of carbonyl compounds in selected public places in Hangzhou, China

The concentrations of six carbonyl compounds in indoor air were measured for selected public places in Hangzhou, including shopping centers, supermarkets, furniture store, inter-city bus stations, railway stations and cinemas. In indoor air of the public places, the mean concentration was 146.5 microg/m(3) for total carbonyls, in which formaldehyde was found to be the most abundant carbonyls with an average value of 90.6 microg/m(3) and followed by acetone and acetaldehyde. Among the selected public places, the furniture store presented the highest carbonyl concentrations in the indoor air, followed by shopping centers, supermarkets, cinemas, while the railway stations and inter-city bus stations presented relatively lower carbonyl concentrations. Carbonyl concentrations in indoor air for the different areas of shopping centers and supermarkets were also investigated. The results showed that the highest carbonyl concentrations were found in restaurant and bedclothes areas for shopping centers and in the cooked food areas for supermarkets. The average ratios of the indoor/outdoor (I/O) for carbonyl concentrations were greater than 1, which indicated that the indoor sources significantly contributed to carbonyls, such as indoor materials and anthropogenic activities. Preliminary estimate of the health risk for staffs, customers and passengers in public places was discussed.     

Health effects of residential radon: a European perspective at the end of 2002

Surveys of indoor radon concentrations, when taken together with estimates of the risk of lung cancer from studies in miners of uranium and other hard rocks, suggest that residential radon is responsible for many thousands of deaths from lung cancer each year in Europe. The vast majority of these deaths are likely to occur in individuals who also smoke cigarettes. Because of the skewed nature of the distribution of the indoor radon concentrations in most populations, most of the deaths will occur in individuals who are exposed at moderate rather than at very high radon concentrations. In order to enable appropriate policies to be developed for managing the consequences of exposure to radon, more reliable estimates of the risk of lung cancer resulting from it are needed. To achieve this, a European Collaborative Group on Residential Radon and Lung Cancer was initiated and its findings should be published in 2004.     

Radon exposure in the thermal spas of Lesvos Island--Greece

The aim of this work is to study the exposure due to radon to bathers and personnel in the spas of Lesvos Island under a specific use pattern. 222Rn concentrations in the supplying water were measured during a long time period. Variations in indoor 222Rn, attached and unattached progenies, and influence of the ambient atmosphere were thoroughly analysed during bath treatment for the purpose of investigating a consequent probable short-term health impact. Concentration peaks both for 222Rn and PAEC were found to appear during bathtubs filling. These peaks considered imposing an additional short-term radiation burden for spa users. The additional doses delivered to bathers during bath treatment were found to be very low and for personnel did not exceed the value of 5 mSv per year.