汽车音响的夏季保养

进入夏季,天气变热,伴随而来的是高温、潮湿、闷热,人开始感觉不舒服,汽车音响也会随着热胀冷缩的规律慢慢在变化,因此,这也成为汽车车主特别关注的部分。下面简单介绍一下汽车音响的夏季保养及注意事项。主机部分:主机部分受天气影响比较大的是电路板和一些塑料元件,电路板里那些电子元件的参数都会随着温度的变化而变化。所以如果车内温度很高的话。

A Three-dimensional Heterogeneous Mass Transfer Model for the Absorption of Gas into Multiphase System

A three-dimensional heterogeneous mass transfer model was proposed to investigate the enhancement of dispersed particles on gas absorption. The strategy to calculate local and overall enhancement factors is proposed. Instead of a global grid, the composite overlapping grid is adopted, which simplifies the setup and solution of the three-dimensional model equations. It is found that dispersed particle hold-up, particle size, liquid-solid partition coefficient of transported component, characteristic contact time, and the shortest distance between particles and gas-liquid interface have major influence on absorption enhancement factor. The particle-particle interaction on gas absorption and the lateral diffusion of transported component in liquid film were studied with the multi-particle simulation. The proposed model predicted the experimental data from the literature reasonably well.

The Role of Hydropower in Climate Change Mitigation and Adaptation： A Review

Hydropower is a clean,renewable,and environmentally friendly source of energy.It produces 3930(TW·h)·a–1,and yields 16% of the world's generated electricity and about 78% of renewable electricity generation(in 2015).Hydropower and climate change show a double relationship.On the one hand,as an important renewable energy resource,hydropower contributes significantly to the avoidance of greenhouse gas(GHG) emissions and to the mitigation of global warming.On the other hand,climate change is likely to alter river discharge,impacting water availability and hydropower generation.Hydropower contributes significantly to the reduction of GHG emissions and to energy supply security.Compared with conventional coal power plants,hydropower prevents the emission of about 3 GT CO2 per year,which represents about 9% of global annual CO2 emissions.Hydropower projects may also have an enabling role beyond the electricity sector,as a financing instrument for multipurpose reservoirs and as an adaptive measure regarding the impacts of climate change on water resources,because regulated basins with large reservoir capacities are more resilient to water resource changes,less vulnerable to climate change,and act as a storage buffer against climate change.At the global level,the overall impact of climate change on existing hydropower generation may be expected to be small,or even slightly positive.However,there is the possibility of substantial variations across regions and even within countries.In conclusion,the general verdict on hydropower is that it is a cheap and mature technology that contributes significantly to climate change mitigation,and could play an important role in the climate change adaptation of water resource availability.However,careful attention is necessary to mitigate the substantial environmental and social costs.Roughly more than a terawatt of capacity could be added in upcoming decades.

Use of Spatial Technologies to Study the Winds＇ Directions in Rub＇ AI-Khali Desert, Saudi Arabia

Studying environmental phenomenon in Rub＇ Al-Khali （Arabic name of＂Empty Quarter＂）, as one of the largest deserts in the world, requires adopting some advanced spatial technologies in conjunction with the data recorded in the field in order to device better understanding. The paper utilizes the technologies of GIS （geographical information systems） and RS （remote sensing） in order to study large amount of weather data recorded in the field from different sources related to oil and gas industry in Rub＇ AI-Khali desert. The main objective is to identify the wind directions and its movement in Kidan areas and the areas south and east of Shaybah in Rub＇ Al-Khali desert. The study used different sources of data mainly recorded by the seismic campaigns＇ base camps and the drilling rig camps or the civil works camps. Wind Roses were created for all metrological weather stations in the study area. Also, the study tried to analyze the dune types using satellite imageries and identify the relation of its shapes to the wind direction. The final aim of the result of this study is to help in planning best locations to build facilities for new major oil and gas project.

Electricity Pricing for Natural Gas CHP Projects The Higher, the Better?

Regarding the state's policy that gives a higher on-grid electricity price to natural gas CHP (combined heat and power) projects, this paper studies the effect of it on the operation of those projects by theoretical analysis and a case study. It concludes that on-grid electricity price on the high side, compared to heat price, will lead power plants to produce more electricity but less heat, thus causing decrease of the plants' thermal eff iciency and harm to energy saving of the whole society.

Opportunities and Challenges of Sino-Australia LNG Cooperation

Australia＇s liquefied natural gas industry~ has been growing rapidly in recent years. As China＇ s natural gas production drops and its demand for clean energy sources, such as natural gas, grows, LNG, as a complement to piped natural gas, will be an important part of China＇s strategy of ensuring its natural gas consumption. Aware of this market opportunity , China＇s three big national oil companies, CNPC, CNOOC and Sinopec have all inw＇sted in Australia＇s LNG sector. Chinese oil companies are facing multiple challenges in their Australian LNG projects, including strict environmental taws and high labor cost. These companies should strengthen communication with local government to create a good investment environment for LNG projects.

Novel consistency control strategy for jet dispensing

A new consistency control method for jet dispensing is proposed. First, the working parameters, namely, viscosity, supply pressure and supply time, are experimentally investigated. Then, the glue viscosity is approximated by a polynomial model using the least square method. Based on this model and temperatme control implemented using the Dahlin principle, the viscosity of the glue can be maintained at a constant value. Then, the viscosity model of the glue is applied to deriving the droplet mass as the nominal model of the temperature controller. The robustness of the temperature controller is analyzed by applying the small gain theory. The glue supply pressure controller is designed using the consistency control strategy, and the robustness is analyzed. Finall）, simulations and experiments are conducted using a jet dispensing control system. The results show that the proposed control strategy can significantly improve the droplet consistency.

CDM Project Activities in China's Iron and Steel Industry:Current Status,Barriers and Development Strategies

China is now facing huge pressure from both the domestic concern of energy security and the global community's call for emission reduction commitment.As one of the major energy consumers and greenhouse gas emitters,China's iron and steel industry has a huge clean development mechanism(CDM) potential.This article both quantitatively and qualitatively analyzes the current status of CDM project activities in the iron and steel industry in China,including characteristics of approved project types,applicable methodologies,and potential technology fields.From the perspective of project implementation,the article summarizes development barriers such as high investment risk,difficulty in project identification,strict requirements on PPDs,long registration waiting time,and etc.Policy suggestions are also put forwarded to help better promote the development of CDM projects in the iron and steel industry.

A Pilot-scale Demonstration of Reverse Osmosis Unit for Treatment of Coal-bed Methane Co-produced Water and Its Modeling

This study presents the first demonstration project in China for treatment of coal-bed methane(CBM) co-produced water and recycling.The work aims to provide a research and innovation base for solving the pollution problem of CBM extraction water.The reverse osmosis(RO) unit is applied to the treatment of CBM co-produced water.The results indicate that system operation is stable,the removal efficiency of the total dissolved solids(TDS) is as high as 97.98%,and Fe,Mn,and F-are almost completely removed.There is no suspended solids(SS) detected in the treated water.Furthermore,a model for the RO membrane separation process is developed to describe the quantitative relationship between key physical quantities-membrane length,flow velocity,salt concentration,driving pressure and water recovery rate,and the water recovery restriction equation based on mass balance is developed.This model provides a theoretical support for the RO system design and optimization.The TDS in the CBM co-produced water are removed to meet the "drinking water standards" and "groundwater quality standards" of China and can be used as drinking water,irrigation water,and livestock watering.In addition,the cost for treatment of CBM co-produced water is assessed,and the RO technology is an efficient and cost-effective treatment method to remove pollutants.

Effects of Insufficient Investment and Overproduction on Iran＇s Oil Production Trend

This paper, using multiple-Hubbert model, forecasts oil production trend of Iran with special focus on Iran＇s insufficient investment for developing recently discovered oilfields and overproduction from mature oilfields. This is mostly due to Iran＇s political and technical limitations to carry out oil and gas projects. The trend of Iran＇s oil production has been forecasted based on a multi-cycle modified Hubbert. Three different scenarios have been assumed. In the first scenario, it is assumed that Iran does not have any limitations to carry out oil and gas projects and develop its oilfields. International sanctions and lack of foreign investment have been taken into account in the second scenario. Overproduction from currently producing mature oilfields and its effect on production trend is investigated in the third scenario. The most important parameter to forecast oil production trend is URR （ultimate recoverable resource）. URR of Iran has been estimated by parabolic fractal curve. Here, based on the plotted parabolic fractal curve for the oil fields, amount of URR of Iran has been calculated that is around 200 Gb. First scenario has two peaks while the second and third scenarios have three peaks. All of the scenarios have forecasted Iran＇s first peak in 1975 at annual production rate of 2 Gb/Year. Based on first scenario, Iran＇s second peak will occur in 2029 at 2.334 Gb/Year. Second scenario has forecasted Iran＇s second and third peaks in 2011 at 1.575 Gb/Year and in 2064 at 2.205 Gb/Year respectively, and third scenario＇s peaks have been estimated to occur in 2011 at 1.573 Gb/Year and in 2061 at 2.030 Gb/Year.

Emissions of SO2, NOx and PMs from Cement Plant in Vicinity of Khoms City in Northwestern Libya

Estimated emissions of gases and particulate matter from two Portland cement plants near Khoms city in northwestern Libya by computer simulation reveal that the SO2, NOx and dust emissions exceed selected international standard limits. The results highlight the need for improved operational procedures to minimize emissions and avoid any possible adverse environmental effects.

Aviation environmental technology and science

Expatiating on the impact of aviation on the environment and aviation environmental protection projects are expounded, and analyzing on the atmosphere pollution and effects on the aviation noise of aircraft discharge. Researching the approach to control aircraft exhaust pollution and noise pollution, and proposing the technology and management measures to reduce air pollution.

Inertisation options for BG method and optimisation using CFD modelling

Spontaneous combustion(sponcom) is one of the issues of concern with the blasting gallery(BG) method of coal mining and has the potential to cause fires, and impact on production and safety, greenhouse gas(GHG) emissions and huge costs involved in controlling the aftermath situations. Some of the research attempts made to prevent and control coal mine fires and spontaneous combustion in thick seams worked with bord and pillar mining methods are presented in this paper. In the study, computational fluid dynamics(CFD) modelling techniques were used to simulate and assess the effects of various mining methods, layouts, designs, and different operational and ventilation parameters on the flow of goaf gases in BG panels. A wide range of parametric studies were conducted to develop proactive strategies to control and prevent ingress of oxygen into the goaf area preventing spontaneous combustion and mine fires.

Determination of Strouhal Numbers at High Reynolds Numbers

Leeward of natural elevations, like mountains and hills, the air flow becomes turbulent and often times damaging and hazardous to aviation and downwind populations. There is currently a trend for massive construction projects, the result of which are megastructures that behave similarly to these natural elevations and create analogous turbulence conditions. Examples five mega projects were analyzed, and it was estimated that the Reynolds number variation in these buildings, is from 6.10g and 7.109, for winds between 10 m/s and 50 m/s. In this work, the authors present a first numerical approach to this phenomenon by calculating the Strouhal numbers induced by winds blowing against large-volume bodies, in the range of high Reynolds numbers. For this study, satellite images depicting von K^irm^n cloud streets leeward of isolated islands were used. The methodology employed was based on a satellite image where streets watch von K^rnfin vortex, from NOAA-ARL （National Oceanic and Atmospheric Administration-Air Resource Laboratory） prognosis was obtained for a grid point near the island, then determined the inversion layer and meteorological data （wind, temperature and pressure）, was measured from the satellite image the distances separating the vortices to calculate the period, the Reynolds number and Strouhal. The studied results of the cases are displayed graphically, where it is possible to observe a data dispersion as well as a rising trend of the Strouhal number as the Reynolds number increases.

Study on the Concept of Per Capita Cumulative Emissions and Allocation Options

Global long-term emission reduction targets need well defined options for equitable allocation of greenhouse gas emissions. Scholars from developing countries put forward the concept of equitable per capita cumulative emission rights. There are four possible operational definitions resulting from this concept. These potential options for allocation of emission rights are expressed with mathematical equations. Through simple simulation, this paper reveals the advantages, disadvantages and characteristics of each option.

Impacts of Sloping Land Conversion Program on the vegetation in loess hilly and gully area of northern Shaanxi

Aiming at alleviating the serious soil erosion, the Chinese government initiated the Sloping Land Conversion Program （SLCP） in 1999. Now; after 8 years of project implementation, the ecological recovery effects of the SLCP have become the hot issue of academic circle. This paper; raking the loess hill and gully area of northern Shaanxi as an example, presents a methodology for assessing the vegetation restoration effect of SLCP with normalized difference vegetation index （NDVI）. The key components include calculation of the Growing Season NDVI （GSNDVI）, and estimation of the NVDI change induced by climate and SLCP, respectively. Based on the method, the NDVI change between 2000 and 2006 was obtained using the GSNDVI that excluded the noise from snow and ice. After the part of total NDVI change caused to： climate variation was estimated using empiric formulae, we obtained the part induced by human factors, i.e. the SLCP The human induced part of ND VI change was considered as an approximation indicating the effect of the SLCP on the vegetation. Finally, we analyzed the ND VI change characters of the whole study area, different slope lands and different land use types by spatial statistics method. Results show that the vegetation condition is significantly improved by the SLCP, particularly land types that directly involved in the SLCP, such as steeply slope farmlands, degraded grasslands, etc.

Including Co-benefits in the CDM of the Power Sector： A Case Study for India

This study examines the effects of the inclusion of co-benefits on the potential capacity of advanced thermal plants with a linear programming model in the CDM （clean development mechanism） in India＇s power sector. It investigates how different marginal damage costs of air pollutants affect the potential capacity of NGCC （natural gas combined cycle） and IGCC （integrated gasification combined cycle） by CDM projects with a scenario analysis. Three results are found from this analysis. First, IGCC and NGCC are installed at lower CER （certified emission reductions） prices when the marginal damage costs of air pollutants are added to the CER prices. Second, the CER prices of $1/tCO2 correspond with the sum of marginal damage costs of air pollutants of $150/t for NGCC and $30/t for IGCC in India＇s power sector. Thus, including the co-benefits into CDM attracts developing countries such as India where coal resource is redundant. Third, the SOx and NOx reduction benefits attained from the CDM projects become large in a grid where IGCC is installed.

Investigation of modification design of the fan stage in axial compressor

The S2 flow path design method of the transonic compressor is used to design the one stage fan in order to replace the original designed blade cascade which has two-stage transonic fan rotors.In the modification design,the camber line is parameterized by a quartic polynomial curve and the thickness distribution of the blade profile is controlled by the double-thrice polynomial.Therefore,the inlet flow has been pre-compressed and the location and intensity of the shock wave at supersonic area have been controlled in order to let the new blade profiles have better aerodynamic performance.The computational results show that the new single stage fan rotor increases the efficiency by two percent at the design condition and the total pressure ratio is slightly higher than that of the original design.At the same time,it also meets the mass flow rate and the geometrical size requirements for the modification design.