转子斜槽对鼠笼电动机损耗的影响

本文提出了一种根据多片有限元模型计算斜槽感应电动机总损耗的技术，这个模型预测该电动机内磁通密并轴向变化的能力初次得到证实。然后将此模型用于研究斜槽是怎样影响感应电动机内的损耗的，并表明斜槽改变了电机内转子铁耗与高频转子焦耳损耗之间的平衡。

Simulation of the Direct Radiative Effect of Mineral Dust and Sea Salt Aerosols in a Doubled Carbon Dioxide Climate

The authors examine the equilibrium climatic response to the direct radiative effect （DRE） of mineral dust and sea salt aerosols in a doubled-CO2 climate with two-way coupling of aerosol-climate interactions.In response to the drier and windier conditions,dust emissions increase by 26％ in the Sahara Desert and by 18％ on the global scale relative to present day.Sea salt emissions increase in high latitudes （＞60°） but decrease in middle latitudes （30°-60°） of both hemispheres due to the poleward shift of westerlies,leading to a 3％ decrease in global emissions.The burdens of dust and sea salt increase by 31％ and 7％ respectively,because reductions in rainfall over the tropical oceans increase the lifetime of particles in the warmer climate.The higher aerosol loading in the doubled-CO2 climate reinforces aerosol DRE by -0.2 W m-2,leading to an additional cooling of 0.1℃ at the surface compared with the climatic effects of aerosols in present day.The additional cooling from changes in natural aerosols compensates for up to 15％ of the regional warming induced by doubled CO2.

Geoengineering: Basic science and ongoing research efforts in China

Geoengineering （also called climate engineering）, which refers to large-scale intervention in the Earth＇s climate system to counteract greenhouse gas-induced warming, has been one of the most rapidly growing areas of climate research as a potential option for tackling global warming. Here, we provide an overview of the scientific background and research progress of proposed geoengineering schemes. Geo- engineering can be broadly divided into two categories： solar geoengineering （also called solar radiation management, or SRM）, which aims to reflect more sunlight to space, and carbon dioxide removal （CDR）, which aims to reduce the CO2 content in the atmosphere. First, we review different proposed geoengineering methods involved in the solar radiation management and carbon dioxide removal schemes. Then, we discuss the fundamental science underlying the climate response to the carbon dioxide removal and solar radiation management schemes. We focus on two basic issues： 1） climate response to the reduction in solar irradiance and 2） climate response to the reduction in atmospheric COe. Next, we introduce an ongoing geoengineering research project in China that is supported by National Key Basic Research Program. This research project, being the first coordinated geoengineering research program in China, will systematically investigate the physical mechanisms, climate impacts, and risk and governance of a few targeted geoengineering schemes. It is expected that this research program will help us gain a deep understanding of the physical science underlying geoengineering schemes and the impacts of geoengineering on global climate, in particular, on the Asia monsoon region.

Verification of the stomatal conductance of Nebbiolo grapevine

Wine is one of the most important Italian export products,and Nebbiolo is one of the most respected Italian grapes. In the summer of 2007,a measurement campaign was carried out in a Nebbiolo vineyard located in Vezza d’Alba,near Cuneo,Italy. Using a gauge of trade gases and some other instruments,we recorded the stomatal conductance and also some physiological parameters useful for estimating the dependence of stomatal conductance on environmental variables. The goal of this experiment was improving the parameterization of grapevine evapotranspiration through the assessment of the stomatal conductance and,in particular,of the functional dependence of the stomatal conductance on the following variables:the photosynthetically active radiation,the atmospheric temperature,the atmospheric moisture deficit,and the carbon dioxide concentration. The observations allowed us to check and,in some cases,to adapt the existing general parameterizations found in literature. The results showed some significant differences with the existing parameterizations concerning the atmospheric temperature,the atmospheric moisture deficit,and the carbon dioxide concentration. The parameterizations obtained in this experiment,although referring to a specific plant and site(namely the Nebbiolo at Vezza d’Alba),could allow assessment of the best environmental conditions under which the Nebbiolo grapevine production is the best,and in future could be tested for other grapevines or climates.

Will typhoon over the western North Pacific be more frequent in the Blue Arctic conditions?

How would typhoon activity over the western North Pacific change for various scenarios of future global warming?Using the model projections of the Coupled Model Intercomparison Project phase 3(CMIP 3)under the SRES A1B scenario,we generated summer(September)ice-free Arctic conditions,also referred to as Blue Arctic conditions,and then used the corresponding monthly sea surface temperature(SST)and a set of CO2concentrations to drive an AGCM model to simulate the resulting changes in background conditions affecting typhoon activity over the western North Pacific.Our results show that,during typhoon season(June to October),atmospheric and ocean circulations over the western North Pacific would be significantly different from the present circulations.Changes in the vertical shear of zonal wind and outgoing longwave radiation(OLR)in the western North Pacific are favorable for westward and northward shift,respectively,of the location of typhoon genesis.Moreover,changes in the above fields over the key area may be conducive to less frequent typhoons.In addition,the tropical cyclone genesis potential index(GPI)over the western North Pacific would decrease(increase)east(west)of 150°E(140°E).