莫菲氏管下大量空气排出的两种方法的对比

目的:探讨一种排出莫菲氏管下大量空气的更有效方法。方法:设定几个长度的空气段,用输液管缠绕手指法和传统下排法两种方法对各个空气段各排气5次,通过对损失液体量、成功率进行对比观察。结果:上排法损失液体量明显少于下排法,空气段越短,上排法成功率越高。结论:上排法操作简便、快捷、能避免污染和浪费药液,60cm以下空气段均可采用上排法。

正压通风排烟技术在建筑火灾中的应用

正压通风防烟技术目前已在国内外得到了广泛应用,但如何运用正压通风技术来排除建筑火灾中的烟气还是一个新的研究课题。本文对于正压通风排烟技术在建筑火灾方面的应用研究做一介绍和分析。 一、正压通风排烟技术的可行性 在建筑火灾中,利用正压通风进行排烟的原理很简单,即用鼓风机把大量空气以一定流速送入着火房间。

优秀长跑运动员的呼吸节奏

美国纽约大学的生理学家兼长跑教练员戴尼埃尔斯的研究证明,所有优秀长跑运动员在比赛中的呼吸节奏几乎完全一样,通常,他们在比赛中并不专门注意呼吸。

用太阳能生产水泥

制水泥需要消耗大量的能源。生产一袋50千克的水泥,就需要耗费5千克石油,或者7至9千克的煤,如使用木材作燃料,则要11千克。一些国家由于大量制造水泥,导致了森林被砍伐,森林资源正在逐步减少。 瑞士阿高维州维利干城的保尔——歇莱尔研究所的研究人员,研制了一种尖帽形的太阳能反应器,太阳光直接进入并聚光后,大量空气不断产生石灰岩粉未,像旋风一样滚滚而起。

Simulated seasonal variations in nitrogen wet deposition over East Asia

The regional air quality modeling system Regional Atmospheric Modeling System–Community Multiscale Air Quality was applied to estimate the spatial distribution and seasonal variation in nitrogen wet deposition over East Asia in 2010. The simulated results were evaluated by comparing modeled precipitation rates and ion concentrations, such as ammonium（NH_4~＋）, nitrate（NO_3^-）, and sulfate, in rainwater, against observations obtained from Acid Deposition Monitoring Network in East Asia and meteorological stations in China. Comparison of simulated and observed precipitation showed that the modeling system can reproduce seasonal precipitation patterns reasonably well. For major ion species, the simulated results in most cases were in good agreement with those observed. Analysis of the modeled wet deposition distributions indicated that China experiences noticeable variation in wet deposition patterns throughout the year. Nitrogen wet deposition（NH_4~＋ ＋ NO_3^-） during summer and spring accounted for 71% of the annual total（3.9 Tg N yr^（-1））, including 42.7% in summer. Precipitation plays a larger role in the seasonal variation of wet deposition; whereas, aerosol concentrations affect its distribution patterns. In China, the amount of annual nitrogen wet deposition ranged from 1 to 18 kg N ha^（-1）. Nitrogen in wet deposition was mainly in the form of NH_4~＋, accounting for 65.76% of the total amount, and the molar ratio of NH_4~＋∕NO_3^- was mostly more than 1, indicating a relatively larger effect from agricultural activities.

Numerical Simulation of CO_2 Concentrations in East Asia with RAMS-CMAQ

The regional air quality modeling system RAMS-CMAQ(Regional Atmospheric Modeling System and Models-3 Community Multi-scale Air Quality) was developed by incorporating a vegetation photosynthesis and respiration module(VPRM) and used to simulate temporal-spatial variations in atmospheric CO2 concentrations in East Asia,with prescribed surface CO2 fluxes(i.e.,fossil fuel emission,biomass burning,sea-air CO2 exchange,and terrestrial biosphere CO2 flux).Comparison of modeled CO2 mixing ratios with eight ground-based in-situ measurements demonstrated that the model was able to capture most observed CO2 temporal-spatial features.Simulated CO2 concentrations were generally in good agreement with observed concentrations.Results indicated that the accumulated impacts of anthropogenic emissions contributed more to increased CO2 concentrations in urban regions relative to remote locations.Moreover,RAMS-CMAQ analysis demonstrates that surface CO2 concentrations in East Asia are strongly influenced by terrestrial ecosystems.

The Structure of a Typical Mei-Yu Front Identified by the Equivalent Temperature

In China's Mainland, the summer monsoon rainy band is referred to as the mei-yu precipitation front, which extends northward from South China to the Yangtze River, Huaihe River, and Yellow River, depending on the season. This paper describes the structure of the mei-yu front associated with a persistent heavy rainfall event that occurred in the summer of 2007. The mei-yu front occurs when the subtropical oceanic warm, moist air mass and the extra tropical continental dry, cold air mass converge on the lee side of the Tibetan Plateau. The authors defined the equivalent temperature using two terms of dry-air temperature and the specific humidity and calculated its horizontal gradient to indicate the mei-yu front. The vertical structure of the mei-yu front and the moist thermal winds surrounding it were examined based on the equivalent temperature.

Calculation of stratosphere–troposphere exchange in East Asia cut-off lows:cases from the Lagrangian perspective

In this study,the authors focus on the cut-off low pressure systems（COLs）lingering over East Asia in late spring and early summer and quantify the two-way stratosphere–troposphere exchange（STE）by 3D trajectory integrations,achieved using a revised version of the UK Universities Global Atmospheric Modelling Programme Offline Trajectory Code（Version 3）.By selecting 10 typical COLs and calculating the cross-tropopause air mass fluxes,it is found that stratosphere-to-troposphere transport（STT）fluxes exist in the center of COLs;and in the periphery of the COL center,troposphereto-stratosphere transport（TST）fluxes and STT fluxes are distributed alternately.Net transport fluxes in COLs are from stratosphere to troposphere,and the magnitude is about 10-4 kg m-2 s-1.The ratio between the area-averaged STT and TST fluxes increases with increasing strength of the COLs.By adopting appropriate residence time,the spurious transports are effectively excluded.Finally,the authors compare the results with previous studies,and find that the cross-tropopause fluxes（CTFs）induced by COLs are about one to two orders of magnitude larger than global CTFs.COLs play a significant role in local,rapid air mass exchanges,although they may only be responsible for a fraction of the total STE.

Test Rig Effect on Performance Measurement for Low Loaded Large-Diameter Fan for Automotive Application

Large diameter fans with low solidity are widely used in automotive application for engine cooling. Their designs with small chord length help reducing the torque on the electrical motor and providing a good aerodynamic compromise between several operating conditions, some of these being at high flow rate. Their global performances are measured according to the ISO standard DP 5801, which allows comparison of results from different facilities. However, some variations in global performances are observed when considering results from two different test rigs. On a fan selected for the purpose of this study, up to 6 % of efficiency is lost on the worst case. As efficiency is more than ever a key factor to select a component, some experimental and numerical investigations were conducted to analyze the fan behavior on each facility. Two sets of measurement and simulation are performed and compared. Geometries considered for the domain of computation include the test rig plenum, the torquemeter, the ground and a large domain for the atmospheric conditions. The exact fan geometry with tip clearance and under-hub ribs is also considered. Numerical results show a good agreement with experiment in both cases when convergence is reached and for low flow rate when computations are switched to unsteady mode. Comparisons show that simulations are able to capture the different fan behaviors depending on the confguration and those efficiency losses previously observed are correctly predicted. These results are further analyzed to perform some post-processing. Blade loading remains identical for both cases but disparities appear in the wake and its interaction with the surrounding. Tiny details that are often neglected during experiment and/or simulation appear to be the cause of slight variations. Position of the torquemeter and shape of the plenum are among the parameters that various and that have cumulative effects. Efficiency being a ration of pressure and torque, variations are rather important. Finally, these results are discussed in terms of rules for conception and a new geometry less sensible to loss of efficiency is proposed.

Spatial Distributions of Atmospheric Radiative Fluxes and Heating Rates over China during Summer

The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the lower atmosphere over central China to be smaller than the fluxes over southern and northern China by generating more clouds. The existence of a larger quantity of clouds over central China reflects a greater amount of solar radiation back into space. The vertical gradients of upward shortwave radiative fluxes in the atmosphere below 8 km are greater than those above 8 km. The latitudinal-altitude distributions of downward longwave radiative fluxes show a slantwise decreasing trend from low latitudes to high latitudes that gradually weaken in the downward direction. The upward longwave radiative fluxes also weaken in the upward direction but with larger gradients. The maximum heating rates by solar radiation and cooling rates by longwave infrared radiation are located over 28 40°N at 7 8 km mean sea level (MSL), and they are larger than the rates in the northern and southern regions. The heating and cooling rates match well both vertically and geographically.

Atmospheric PCDD/Fs in Southeastern China

Air samples were collected simultaneously at Guiyu （an electronic waste recycling site）, three urban sites in Hong Kong and two urban sites in Guangzhou, southeast China on August 20, 2004 and January 24, 2005, respectively. Seventeen congeners of PCDD/Fs （polychlorinated dibenzo-p-dioxins dibenzofurans） were measured. The results showed that the concentration of PCDD/Fs in Guiyu was 6,721 fg/m3, which was 1.5 times of Guangzhou and 3.1 times of Hong Kong sites. TEQ （total toxic equivalent） of Guiyu, Guangzhou and Hong Kong air samples were 598, 202 and 137 fg I-TEQ/m3, respectively. A clear seasonal variation of PCDD/Fs in the air was found in both Guangzhou and Hong Kong sites. The concentration of 2,3,7,8-TCDD （2,3,7,8-Tetrachlorodibenzodioxin） in Guiyu was 54 fg/m3, higher than the whole year standard of 30 fg/m3 imposed by USA （Indiana, Kansas and Washington）. This was primarily due to the incomplete combustion of e-wastes （e.g., plastic chips, wire insulations, PVC （polyvinyl chloride polymer） materials and metal scraps）.

Engineering Solutions towards Cost-Effective Sustainable Environment and Living

One important area where the development of economically viable products can improve the quality and comfort of human existence is natural ventilation inside a building. Despite the wide distribution of air pollutant sources, the concentration of indoor pollutants may be the dominant risk factor in relation to personal exposure, as most people spend an average of 87% and 6% of their time within enclosed rooms and vehicles, respectively. Under these circumstances, wind driven rotating ventilators, which use natural energy and are cheap to manufacture, install and maintain, can become very effective non-polluting means of alleviating the problems within enclosed spaces. The author has been pioneering design and performance studies of environment friendly products such as the rooftop ventilator for over a decade at the University of New South Wales in Australia. The purpose of this paper is to detail the basic working principles of this ventilator and the series of detailed experimental and numerical investigations that has been performed in the optimization of the rooftop ventilator in terms of performance with higher air mass extraction rate and improved safety in operation has been achieved. Findings from these studies have been incorporated in the design of ventilators that are now commercially produced and marketed throughout the world by CSR Edmonds Pry Ltd of Australia. The conduct and outcomes of these works form the basis of this keynote paper.

长跑时应该怎样呼吸?

每个人从生下来就会呼吸,而且时时刻刻都要进行呼吸,呼吸停止,生命也就结束了。看起来呼吸是一件极为普通平常的事,其实不然,在长跑运动时,就有个呼吸方法的问题。这是长跑运动的特点所决定的。

飞机为什么要全密封

随着我国航空事业的发展,同学们跟着爸妈外出旅游乘坐飞机的机会越来越多,你们可曾想过,为什么飞机的设计通常都是密封的? 多年前,美国一架航天飞机升空不久。

The seasonal cycle of redistribution of atmospheric mass between continent and ocean in the Northern Hemisphere

Using NCEP/NCAR and ERA-40 reanalyses,we studied the seasonal cycle of redistribution of air mass between continents and oceans over the Northern Hemisphere.Our results demonstrate that air mass in the Northern Hemisphere shifts clearly between continents and oceans when the season cycles.In July,the air mass reaches its lowest over Eurasia and its highest over the Pacific,and the opposite occurs in January.However,a different scenario is observed over the north Atlantic;the accumulated air mass reaches its maximum there in May.The maintenance of the accumulation or loss of air mass in a region is found to be related to the areal mean air mass flux divergence and the difference between precipitation and evaporation in an air column.The zonal-vertical circulations change with season,with the air ascent and decent reversed between land and sea.Besides,there also exists a noticeable difference of water vapor content of the air between continents and oceans,and this difference is season-dependent.Physically,the vapor content is able to significantly affect the atmosphere in absorbing solar short-and earth’s long-wave radiations,hence influencing atmospheric thermal conditions.The land-sea thermal contrasts inclusive of the diabatic heating rate changes their signs with season going on,resulting in the reversal of orientations of the temperature gradient.These thermal forcings not only facilitate the formation of the monsoons but also indirectly induce the seasonal cycle of the air mass exchanging over regions between continents and oceans.

Atmospheric correction of remote sensing imagery based on the surface spectrum’s vector space

Due to the atmosphere effect,the qualities of images decrease conspicuously,practically in the visible bands,in the processing of earth observation by the satellite-borne sensors.Thus,removing the atmosphere effects has become a key step to improve the qualities of images and to retrieve the actual reflectivity of surface features.An atmospheric correction approach,called ACVSS(Atmospheric Correction based Vector Space of Spectrum),is proposed here based on the vector space of the features' spectrum.The reflectance image of each band is retrieved first according to the radiative transfer equation,then the spectrum's vector space is constructed using the infrared bands,and finally the residual errors of the reflectance images in the visible bands are corrected based on the pixel position in the spectrum's vector space.The proposed methodology is verified through atmospheric correction on Landsat-7 ETM+ imagery.The experimental results show that our method is more accurate and the corrected image is more distinct,compared with those offered by current popular atmospheric correction software.

Analysis of effective capacity for free-space optical communication systems over gamma-gamma turbulence channels with pointing errors

To facilitate the efficient support of quality-of-service(Qo S)for promising free-space optical(FSO)communication systems,it is essential to model and analyze FSO channels in terms of delay Qo S.However,most existing works focus on the average capacity and outage capacity for FSO,which are not enough to characterize the effective transmission data rate when delay-sensitive service is applied.In this paper,the effective capacity of FSO communication systems under statistical Qo S provisioning constraints is investigated to meet heterogeneous traffic demands.A novel closed-form expression for effective capacity is derived under the combined effects of atmospheric turbulence conditions,pointing errors,beam widths,detector sizes and Qo S exponents.The obtained results reveal the effects of some significant parameters on effective capacity,which can be used for the design of FSO systems carrying a wide range of services with diverse Qo S requirements.