Optimal sizing and allocation of distributed generators(DGs)have become essential computational challenges in improving the performance,efficiency,and reliability of electrical distribution networks.Despite extensive ...Optimal sizing and allocation of distributed generators(DGs)have become essential computational challenges in improving the performance,efficiency,and reliability of electrical distribution networks.Despite extensive research,existing approaches often face algorithmic limitations such as slow convergence,premature stagnation in local minima,or suboptimal accuracy in determining optimal DG placement and capacity.This study presents a comprehensive scientometric and systematic review of global research focused on computer-based modelling and algorithmic optimization for renewable DG sizing and placement.It integrates both quantitative and qualitative analyses of the scholarly landscape,mapping influential research domains,co-authorship structures,the articles’citation networks,keyword clusters,and international collaboration patterns.Moreover,the study classifies and evaluates the most prominent objective functions,key computational models and optimization algorithms,DG technologies,and strategic approaches employed in the field.The findings reveal that advanced algorithmic frameworks substantially enhance network stability,minimize real power losses,and improve voltage profiles under various operational constraints.This review serves as a foundational resource for researchers and practitioners,highlighting emerging algorithmic trends,modelling innovations,and data-driven methodologies that can guide future development of intelligent,optimization-based DG integration strategies in smart distribution systems.展开更多
The concept of electroosmotically driven flow is built around understanding how the ionized particles or fluid are driven to flow by electroosmosis forces. Apart from the major applications of this concept to micro f...The concept of electroosmotically driven flow is built around understanding how the ionized particles or fluid are driven to flow by electroosmosis forces. Apart from the major applications of this concept to micro flow control elements which have been explored in parallel with the rapid developments in micro fabrication technologies, the present focus is on its application to biomimetics. As soil animals (in fact all living creatures) such as earthworms and dung beetles carry bioelectricity, the relative movement between the creatures and the surrounding soil which is a multi-component medium with moist content will generate electrophoresis or electroosmosis forces. Such forces drive the ionized moist content, normally water, to migrate from positive to negative poles under the action of electric double layer (EDL) effect, and effectively reduce the adhesion or drag.Predicting the electroosmotically driven flow in the vicinity of biological and animal surfaces is a key problem of drag/adhesion reduction and biomimetics design. The aim of this article is to demonstrate how the theory of electroosmotically driven flow has developed and to describe its broader significance for anti adhesion of soil animals and biomimetics design of soil machinery tools.展开更多
In view of the fact that large scale vortices play the substantial role of momentum transport in turbulent flows, large eddy simulation （LES） is considered as a better simulation model. However, the sub-grid scale ...In view of the fact that large scale vortices play the substantial role of momentum transport in turbulent flows, large eddy simulation （LES） is considered as a better simulation model. However, the sub-grid scale （SGS） models reported so far have not ascertained under what flow conditions the LES can lapse into the direct nu-merical simulation. To overcome this discrepancy, this paper develops a swirling strength based the SGS model to properly model the turbulence intermittency, with the primary characteristics that when the local swirling strength is zero, the local sub-grid viscosity will be vanished. In this paper, the model is used to investigate the flow characteris-tics of zero-incident incompressible turbulent flows around a single square cylinder （SC） at a low Reynolds number range Re ∈ [103, 104]. The flow characteristics investigated include the Reynolds number dependence of lift and drag coefficients, the distributions of time-spanwise averaged variables such as the sub-grid viscosity and the logarithm of Kolmogorov micro-scale to the base of 10 at Re=2 500 and 104, the contours of spanwise and streamwise vorticity components at t = 170. It is revealed that the peak value of sub-grid viscosity ratio and its root mean square （RMS） values grow with the Reynolds number. The dissipation rate of turbulent kinetic energy is larger near the SC solid walls. The instantaneous factor of swirling strength intermittency （FSI） exhibits some laminated structure involved with vortex shedding.展开更多
The auto-correlation function and the cross-correlation of an autonomous stochastic system with nonlinear time-delayed feedback are investigated by using the stochastic simulation method. There are prominent differenc...The auto-correlation function and the cross-correlation of an autonomous stochastic system with nonlinear time-delayed feedback are investigated by using the stochastic simulation method. There are prominent differences be- tween the roles of quadratic time-delayed feedback and cubic time-delayed feedback on the correlations of an autonomous stochastic system. Under quadratic time-delayed feedback, the nonlinear time delay fails to improve the noisy state of the autonomous stochastic system, the auto-correlation decreases monotonously to zero, and the cross-correlation increases monotonously to zero with the decay time. Under cubic time-delayed feedback, the nonlinear time delay can improve the noisy state of the autonomous stochastic system; the auto-correlation and the cross-correlation show periodical oscillation and attenuation, finally tending to zero with the decay time. Comparing the correlations of the system between with nonfinear time-delayed feedback and linear time-delayed feedback, we find that nonlinear time-delayed feedback lowers the correlation strength of the autonomous stochastic system.展开更多
By using the fundamental equations of axisymmetric shallow shells of revolution, the nonlinear bending of a shallow corrugated shell with taper under arbitrary load has been investigated. The nonlinear boundary value ...By using the fundamental equations of axisymmetric shallow shells of revolution, the nonlinear bending of a shallow corrugated shell with taper under arbitrary load has been investigated. The nonlinear boundary value problem of the corrugated shell was reduced to the nonlinear integral equations by using the method of Green＇s function. To solve the integral equations, expansion method was used to obtain Green＇s function. Then the integral equations were reduced to the form with degenerate core by expanding Green＇s function as series of characteristic function. Therefore, the integral equations become nonlinear algebraic equations. Newton＇ s iterative method was utilized to solve the nonlinear algebraic equations. To guarantee the convergence of the iterative method, deflection at center was taken as control parameter. Corresponding loads were obtained by increasing deflection one by one. As a numerical example,elastic characteristic of shallow corrugated shells with spherical taper was studied.Calculation results show that characteristic of corrugated shells changes remarkably. The snapping instability which is analogous to shallow spherical shells occurs with increasing load if the taper is relatively large. The solution is close to the experimental results.展开更多
Mechanism interaction between cracks with different orientation angles is analyzed based on the principle of superposition and a flattening method. It is found that the maximum interaction effect does not occur when t...Mechanism interaction between cracks with different orientation angles is analyzed based on the principle of superposition and a flattening method. It is found that the maximum interaction effect does not occur when the microcrack is along the direction parallel or perpendicular to the principal tensile stress, which is different from the conclusion drawn by Ortiz （1987）. The mechanism of microcrack generation and the effect of the microcrack zone on the main crack tip are studied. It is concluded that the microcrack zone has effect on the main crack tip, which increases with the increase of microcrack density and length.展开更多
With rapid development of the construction industry in China, lots of construction materials are being widely reused. Meanwhile, more and more materials for building remover or demolition enter into the environment as...With rapid development of the construction industry in China, lots of construction materials are being widely reused. Meanwhile, more and more materials for building remover or demolition enter into the environment as a result. However, China is facing big building garbage pollution, with simple disposal methods and low efficiency, which urgently needs to be improved. The paper takes Chongqing as an example to illustrate existing problems in this field and then puts forward corresponding countermeasures from the aspects of economy, technology, management and policy, aiming at enhancing the level of construction waste disposal in China.展开更多
In most urban redevelopment projects that take place in Hong Kong, the Urban Renewal Authority (URA) will offer compensation to an owner-occupier based on the market value of the property. The basis of market value as...In most urban redevelopment projects that take place in Hong Kong, the Urban Renewal Authority (URA) will offer compensation to an owner-occupier based on the market value of the property. The basis of market value assessment is defined as a seven-year-old flat in a comparable quality building, situated in a similar locality in terms of characteristics and accessibility, and located at the middle floor with average orientation. However, little was done in exploring the application and the integration of mass valuation technique in the compulsory acquisition valuation area. This paper endeavors to illustrate the prospects of using mass valuation techniques to value high-rise and strata-title dilapidated buildings by adopting a standardization statistical method to derive resumption estimates.展开更多
Increasing attention is being paid to the reduction of emissions from non-road mobile machinery,and many policies to promote the reduction have been established in countries and regions around the world,including the ...Increasing attention is being paid to the reduction of emissions from non-road mobile machinery,and many policies to promote the reduction have been established in countries and regions around the world,including the United States,Canada,the European Union,and China.This paper reviews these policies and analyzes two successful grant programs in the USA.Depending on the findings from the research,it is suggested that the Chinese government should tighten emission standards,introduce more financial subsidies,and strengthen supervision.展开更多
With the measurement of dividend payout ratio, logistic regression index value and the firm size financing constraints, this paper investigated the investment behavior of China’s manufacturing firms over the period f...With the measurement of dividend payout ratio, logistic regression index value and the firm size financing constraints, this paper investigated the investment behavior of China’s manufacturing firms over the period from 1998 to 2003, and the relationship between financing constraints and corporate investment using the OLS regression method. The empirical evidence shows that there are certain extent financing constraints in China’s manufacturing firms, but the results are different with different variables to measure the financing constraints.展开更多
The article represents research on ways to make the management of real estate companies more efficient, starting from their structural organization. The organizational structure of the enterprise is a basic component ...The article represents research on ways to make the management of real estate companies more efficient, starting from their structural organization. The organizational structure of the enterprise is a basic component of the general structure of the company and reflects the “anatomy of the enterprise” and the way of its conception, detailing, and implementation directly influence the activities required to achieve the objectives of the enterprise. On closer examination of a series of organizational charts of real estate management companies, the author observed a tendency to use organizational structures that are inefficient. The main objectives of this article are to bring into the practice of real estate management a model of beneficial organizational structure, both for the real estate management companies and for the construction companies that, besides the building activity, also deal with the management of their own real estate, and to emphasize the particular importance of the organizational structure of the company. The appreciation of the organizational structure represents the process of knowledge, understanding, and explanation of the existing situation through a detailed analysis of the factors that influence its condition through: the enterprise development strategy;the type and complexity of services;the size of the enterprise;the quality of human resources;the changes that take place in the external environment of the company, and last but not least, the legal framework and the statutes of the enterprise.展开更多
Sargassum is an indicator of progressive pollution in the seas because it causes lack of light and lack of oxygenation.It arrives in the Mexican Caribbean between the months of April and September,causing a bad smell ...Sargassum is an indicator of progressive pollution in the seas because it causes lack of light and lack of oxygenation.It arrives in the Mexican Caribbean between the months of April and September,causing a bad smell that it has after its decomposition,a heavy load of heavy metals,as well as being an inconvenience for the inhabitants because it causes losses for tourism in that region.There are several ways to take advantage of these algae and one of them is to generate biomass to obtain a biofuel.The objective of this study was to determine the viability of sargassum(two varieties)as a substrate to obtain biogas in anaerobic co-digestion with sludge from a WWTP(Wastewater Treatment Plant).Two forms of drying were also applied to the two varieties of algae.It was obtained that sargassum is a good component to co-digest because it does not destabilize the process and good biogas production is achieved.展开更多
A good acoustic environment is absolutely essential to maintaining a high level satisfaction and moral health among residents. Noise and other boresome sounds come from both in- door and outdoor sources. For the resid...A good acoustic environment is absolutely essential to maintaining a high level satisfaction and moral health among residents. Noise and other boresome sounds come from both in- door and outdoor sources. For the residential buildings adjacent to heavy traffic roads, outdoors traffic noise is the main source that affects indoor acoustic quality and health. Ventilation and outdoor noise prevention become a pair of contradictions for the residents in China nowadays for those buildings adjacent to heavy traffic roads. It is investigated that traffic noise emission is mainly con- stituted by the motors of trucks, buses and motorcycles as well as brake. In this paper, two methods of traffic noise reduction on the indoor sound environment and comfort are carried out to study and compare the residential buildings adjacent to heavy traffic roadway in a city. One is to install noise barriers on the two sides of the roadway, which consist of sound-proof glass and plas- tic materials. The effect of sound-insulation of this method is heavily dependent on the relative distance between the noise bar- rier and indoors. A reduction of sound with an average pressure level of 2–15dB is achieved on the places behind and under the noise barrier. However, for the equivalent of noise barrier height, the noise reduction effect is little. As for the places of higher than the noise barrier, the traffic noise will be even strengthened by 3–7dB. Noise increment can be seen at the points of distance farther than 15m and height more than noise barrier; the noise reduction effect is not satisfactory or even worsened. In addition, not every location is appropriate to install the noise barrier along the heavy traffic roads. The other method of noise reduction for the buildings adjacent to heavy traffic is to install the airproof and soundproof windows, which is the conversion from natural venti- lation to mechanical ventilation. A reduction of sound with an average pressure level of 5dB to 17dB can be achieved compared with common glass windows, if adopting sound proof glass win- dows. These two methods are helpful to isolate high frequency noise but not for low frequency noise. For those frequency noises, installing thick and cotton curtain and porous carpet can only decrease 2.4–4.5dB, which hardly contributes to indoor sound comfort, so further study is demanded to cut down traffic noise, especially to cut down the low frequency noise.展开更多
The definition of pillar industry is stated and its indicators, including the proportion of added value in the GDP, the degree of industry correlation, the income elasticity of demand, and the growth rate of employmen...The definition of pillar industry is stated and its indicators, including the proportion of added value in the GDP, the degree of industry correlation, the income elasticity of demand, and the growth rate of employment will be discussed. And then index weighing is determined based on the degree of importance. The result of the quantitative analysis of real estate industry in Chongqing suggests that its first three evaluating indicators live up to the index requirement of a pillar industry while its degree of industry correlation is not satisfactory. An overall evaluation indicates that the real estate industry in Chongqing meets the requirements of pillar industry.展开更多
The incorrect disposal of the waste generated in the municipalities contributes to water and soil contamination,resulting in a real concern in order to find an adequate disposal as well as obtain by-products that can ...The incorrect disposal of the waste generated in the municipalities contributes to water and soil contamination,resulting in a real concern in order to find an adequate disposal as well as obtain by-products that can be used to reduce CO2 emissions.Anaerobic digestion turns out to be the most efficient treatment,both in environmental and economic terms.The objective of this study is to evaluate the anaerobic co-digestion process in phases as an alternative for the treatment of municipal waste:sludge from water treatment plants and the biodegradable part of Municipal Solid Waste(MSW),for three HRTs(Hydraulic Retention Times).Testing results show up a max elimination of 70.68%in VS(Volatile Solids)and 74.01%in COD(Chemical Oxygen Demand).With these percentages of elimination on average,15.96 L/d of biogas was produced,for each kg of COD eliminated 0.56 m3 of biogas was produced and for each kg of SV 0.85 m3 and methane of 50.10%.展开更多
The world has experienced 3 Industrial Revolutions.Right now,we are at the beginning of the 4th Industrial Revolution.4.0 Revolution is based on the digital revolution,characterized by the increasingly popular interne...The world has experienced 3 Industrial Revolutions.Right now,we are at the beginning of the 4th Industrial Revolution.4.0 Revolution is based on the digital revolution,characterized by the increasingly popular internet and mobile,by smaller and more powerful semiconductors at cheaper price and by Artificial Intelligence.Digital technologies with computer hardware,software and networks are becoming more and more complex,more integrated,thus transforming society.Faced with the unprecedented impact of the 4.0 Revolution,depending on the size of the economy and the level of technology,countries around the world have policies to adapt,catch up and take advantage of the achievements of the revolution.This revolution serves the sustainable development of our country.This article summarizes the policies of some countries such as Germany,the United States,Japan,Singapore,Republic of Korea,India,China,Taiwan,...under the impact of the 4.0 Revolution;thereby drawing lessons for Vietnam in the process of implementing the 4.0 Revolution to avoid negative impacts,take advantage of the pre-eminence of the revolution in socio-economic development.展开更多
The implementation of modular multilevel converters(MMC)in an electric ship to create a medium voltage direct current(MVDC)energy conversion system that is efficient,small,dependable,and easily scalable has garnered c...The implementation of modular multilevel converters(MMC)in an electric ship to create a medium voltage direct current(MVDC)energy conversion system that is efficient,small,dependable,and easily scalable has garnered considerable interest.In this research,an improved two-step nearest level control(E-NLC)is presented for MMC with a three-level submodule(3L-SM)as the rectifier of the electric ship power generation units in order to ease the economical and reliable operation of MMCs in MVDC systems.To achieve DC fault-clearing capability,the use of MMC with 3L-SM minimizes the number of switching devices when compared to the regular MMC topology.The suggested E-NLC scheme aims to reduce total harmonic distortion(THD)and achieve the nearest zero common mode voltage(CMV).The output voltage vector of the three phases is tuned using eight candidate vectors capable of suppressing CMV rather than the nearest-level vector,and the rounding function is modified to improve harmonic performance by increasing the approximation between stepped and modulated waves.The generator-connected MMC with THD reduction and CMV elimination maximizes the mover's protection in the generating unit of the electric ship's MVDC system.Simulation and experiment results validate the efficacy of the suggested approach with respect to steady-state and dynamic-state performance.展开更多
Background:Areal bone mineral density(aBMD)applied for osteoporosis diagnosis unavoidably results in the missingdiagnosis in patients with large bones and misdiagnosis in those with small bones.Therefore,we try to fin...Background:Areal bone mineral density(aBMD)applied for osteoporosis diagnosis unavoidably results in the missingdiagnosis in patients with large bones and misdiagnosis in those with small bones.Therefore,we try to find a new adjusted index of bone mineral content(BMC)to make up shortcomings of aBMD in osteoporosis diagnosis.Methods:In this multi-center epidemiological study,BMC and aBMD of lumbar spines(n=5510)and proximal femurs(n=4710)were measured with dual energy X-ray absorptiometry(DXA).We analyzed the correlation between the bone mass and body weight in all subjects including four age groups(<19 years,20-39 years,40-49 years,>50 years).And then the body weight was used for standardizing BMC(named wBMC)and applied for the epidemiological analysis of osteoporosis?Results:The correlation of body weight and BMC is 0.839 to 0.931 of lumbar vertebra 1-4(Li_4),and 0.71 to 0.95 of femoral neck in different age groups.When aBMD was applied for diagnosing osteoporosis,the prevalence was 7.55%,16.39%,and 25.83%in patients with a high,intermediate,and low body weight respectively.However,the prevalence was 21.8%,18.03%,and 11.64%by wBMC applied for diagnosing osteoporosis.Moreover,the prevalence of osteoporosis increased by 3.76%by wBMC with the body weight increased by 5 kg.The prevalence decreased by 1.94%when the body weight decreased by 5 kg.Conclusions:wBMC can reduce the missed diagnosis in patients with large body weight and reduce misdiagnosis in those with small body weight.Including children,wBMC may be feasible for osteoporosis diagnosis individuals at any age.展开更多
基金supported and funded by the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University(IMSIU)(grant number:IMSIU-DDRSP2503)。
文摘Optimal sizing and allocation of distributed generators(DGs)have become essential computational challenges in improving the performance,efficiency,and reliability of electrical distribution networks.Despite extensive research,existing approaches often face algorithmic limitations such as slow convergence,premature stagnation in local minima,or suboptimal accuracy in determining optimal DG placement and capacity.This study presents a comprehensive scientometric and systematic review of global research focused on computer-based modelling and algorithmic optimization for renewable DG sizing and placement.It integrates both quantitative and qualitative analyses of the scholarly landscape,mapping influential research domains,co-authorship structures,the articles’citation networks,keyword clusters,and international collaboration patterns.Moreover,the study classifies and evaluates the most prominent objective functions,key computational models and optimization algorithms,DG technologies,and strategic approaches employed in the field.The findings reveal that advanced algorithmic frameworks substantially enhance network stability,minimize real power losses,and improve voltage profiles under various operational constraints.This review serves as a foundational resource for researchers and practitioners,highlighting emerging algorithmic trends,modelling innovations,and data-driven methodologies that can guide future development of intelligent,optimization-based DG integration strategies in smart distribution systems.
文摘The concept of electroosmotically driven flow is built around understanding how the ionized particles or fluid are driven to flow by electroosmosis forces. Apart from the major applications of this concept to micro flow control elements which have been explored in parallel with the rapid developments in micro fabrication technologies, the present focus is on its application to biomimetics. As soil animals (in fact all living creatures) such as earthworms and dung beetles carry bioelectricity, the relative movement between the creatures and the surrounding soil which is a multi-component medium with moist content will generate electrophoresis or electroosmosis forces. Such forces drive the ionized moist content, normally water, to migrate from positive to negative poles under the action of electric double layer (EDL) effect, and effectively reduce the adhesion or drag.Predicting the electroosmotically driven flow in the vicinity of biological and animal surfaces is a key problem of drag/adhesion reduction and biomimetics design. The aim of this article is to demonstrate how the theory of electroosmotically driven flow has developed and to describe its broader significance for anti adhesion of soil animals and biomimetics design of soil machinery tools.
基金Project supported by the National Natural Science Foundation of China(No.11372303)
文摘In view of the fact that large scale vortices play the substantial role of momentum transport in turbulent flows, large eddy simulation （LES） is considered as a better simulation model. However, the sub-grid scale （SGS） models reported so far have not ascertained under what flow conditions the LES can lapse into the direct nu-merical simulation. To overcome this discrepancy, this paper develops a swirling strength based the SGS model to properly model the turbulence intermittency, with the primary characteristics that when the local swirling strength is zero, the local sub-grid viscosity will be vanished. In this paper, the model is used to investigate the flow characteris-tics of zero-incident incompressible turbulent flows around a single square cylinder （SC） at a low Reynolds number range Re ∈ [103, 104]. The flow characteristics investigated include the Reynolds number dependence of lift and drag coefficients, the distributions of time-spanwise averaged variables such as the sub-grid viscosity and the logarithm of Kolmogorov micro-scale to the base of 10 at Re=2 500 and 104, the contours of spanwise and streamwise vorticity components at t = 170. It is revealed that the peak value of sub-grid viscosity ratio and its root mean square （RMS） values grow with the Reynolds number. The dissipation rate of turbulent kinetic energy is larger near the SC solid walls. The instantaneous factor of swirling strength intermittency （FSI） exhibits some laminated structure involved with vortex shedding.
基金Supported by the National Natural Science Foundation of China under Grant No.11265012Yunnan Province Open Key Laboratory of Mechanics in Colleges and Universities
文摘The auto-correlation function and the cross-correlation of an autonomous stochastic system with nonlinear time-delayed feedback are investigated by using the stochastic simulation method. There are prominent differences be- tween the roles of quadratic time-delayed feedback and cubic time-delayed feedback on the correlations of an autonomous stochastic system. Under quadratic time-delayed feedback, the nonlinear time delay fails to improve the noisy state of the autonomous stochastic system, the auto-correlation decreases monotonously to zero, and the cross-correlation increases monotonously to zero with the decay time. Under cubic time-delayed feedback, the nonlinear time delay can improve the noisy state of the autonomous stochastic system; the auto-correlation and the cross-correlation show periodical oscillation and attenuation, finally tending to zero with the decay time. Comparing the correlations of the system between with nonfinear time-delayed feedback and linear time-delayed feedback, we find that nonlinear time-delayed feedback lowers the correlation strength of the autonomous stochastic system.
文摘By using the fundamental equations of axisymmetric shallow shells of revolution, the nonlinear bending of a shallow corrugated shell with taper under arbitrary load has been investigated. The nonlinear boundary value problem of the corrugated shell was reduced to the nonlinear integral equations by using the method of Green＇s function. To solve the integral equations, expansion method was used to obtain Green＇s function. Then the integral equations were reduced to the form with degenerate core by expanding Green＇s function as series of characteristic function. Therefore, the integral equations become nonlinear algebraic equations. Newton＇ s iterative method was utilized to solve the nonlinear algebraic equations. To guarantee the convergence of the iterative method, deflection at center was taken as control parameter. Corresponding loads were obtained by increasing deflection one by one. As a numerical example,elastic characteristic of shallow corrugated shells with spherical taper was studied.Calculation results show that characteristic of corrugated shells changes remarkably. The snapping instability which is analogous to shallow spherical shells occurs with increasing load if the taper is relatively large. The solution is close to the experimental results.
基金supported by the National Natural Science Foundation of China (Nos. 10972072, 50679022, and 10872052)National Basic Research Program of China (No. 2007CB714104)the state Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering at Hohai University (No. 2009585912)
文摘Mechanism interaction between cracks with different orientation angles is analyzed based on the principle of superposition and a flattening method. It is found that the maximum interaction effect does not occur when the microcrack is along the direction parallel or perpendicular to the principal tensile stress, which is different from the conclusion drawn by Ortiz （1987）. The mechanism of microcrack generation and the effect of the microcrack zone on the main crack tip are studied. It is concluded that the microcrack zone has effect on the main crack tip, which increases with the increase of microcrack density and length.
基金Funded by 2011 Construction Science and Technology Project of Chongqing Municipal Commission of Urban-Rural Development(No.2011-1-8)
文摘With rapid development of the construction industry in China, lots of construction materials are being widely reused. Meanwhile, more and more materials for building remover or demolition enter into the environment as a result. However, China is facing big building garbage pollution, with simple disposal methods and low efficiency, which urgently needs to be improved. The paper takes Chongqing as an example to illustrate existing problems in this field and then puts forward corresponding countermeasures from the aspects of economy, technology, management and policy, aiming at enhancing the level of construction waste disposal in China.
文摘In most urban redevelopment projects that take place in Hong Kong, the Urban Renewal Authority (URA) will offer compensation to an owner-occupier based on the market value of the property. The basis of market value assessment is defined as a seven-year-old flat in a comparable quality building, situated in a similar locality in terms of characteristics and accessibility, and located at the middle floor with average orientation. However, little was done in exploring the application and the integration of mass valuation technique in the compulsory acquisition valuation area. This paper endeavors to illustrate the prospects of using mass valuation techniques to value high-rise and strata-title dilapidated buildings by adopting a standardization statistical method to derive resumption estimates.
基金Environment and Conservation Fund:Environmental Research,Technology Demonstration and Conference of the Hong Kong Special Administrative Region,China(Project Ref.55/2019)。
文摘Increasing attention is being paid to the reduction of emissions from non-road mobile machinery,and many policies to promote the reduction have been established in countries and regions around the world,including the United States,Canada,the European Union,and China.This paper reviews these policies and analyzes two successful grant programs in the USA.Depending on the findings from the research,it is suggested that the Chinese government should tighten emission standards,introduce more financial subsidies,and strengthen supervision.
基金Funded by the Natural Science Foundation of China (No. 70372041).
文摘With the measurement of dividend payout ratio, logistic regression index value and the firm size financing constraints, this paper investigated the investment behavior of China’s manufacturing firms over the period from 1998 to 2003, and the relationship between financing constraints and corporate investment using the OLS regression method. The empirical evidence shows that there are certain extent financing constraints in China’s manufacturing firms, but the results are different with different variables to measure the financing constraints.
文摘The article represents research on ways to make the management of real estate companies more efficient, starting from their structural organization. The organizational structure of the enterprise is a basic component of the general structure of the company and reflects the “anatomy of the enterprise” and the way of its conception, detailing, and implementation directly influence the activities required to achieve the objectives of the enterprise. On closer examination of a series of organizational charts of real estate management companies, the author observed a tendency to use organizational structures that are inefficient. The main objectives of this article are to bring into the practice of real estate management a model of beneficial organizational structure, both for the real estate management companies and for the construction companies that, besides the building activity, also deal with the management of their own real estate, and to emphasize the particular importance of the organizational structure of the company. The appreciation of the organizational structure represents the process of knowledge, understanding, and explanation of the existing situation through a detailed analysis of the factors that influence its condition through: the enterprise development strategy;the type and complexity of services;the size of the enterprise;the quality of human resources;the changes that take place in the external environment of the company, and last but not least, the legal framework and the statutes of the enterprise.
文摘Sargassum is an indicator of progressive pollution in the seas because it causes lack of light and lack of oxygenation.It arrives in the Mexican Caribbean between the months of April and September,causing a bad smell that it has after its decomposition,a heavy load of heavy metals,as well as being an inconvenience for the inhabitants because it causes losses for tourism in that region.There are several ways to take advantage of these algae and one of them is to generate biomass to obtain a biofuel.The objective of this study was to determine the viability of sargassum(two varieties)as a substrate to obtain biogas in anaerobic co-digestion with sludge from a WWTP(Wastewater Treatment Plant).Two forms of drying were also applied to the two varieties of algae.It was obtained that sargassum is a good component to co-digest because it does not destabilize the process and good biogas production is achieved.
文摘A good acoustic environment is absolutely essential to maintaining a high level satisfaction and moral health among residents. Noise and other boresome sounds come from both in- door and outdoor sources. For the residential buildings adjacent to heavy traffic roads, outdoors traffic noise is the main source that affects indoor acoustic quality and health. Ventilation and outdoor noise prevention become a pair of contradictions for the residents in China nowadays for those buildings adjacent to heavy traffic roads. It is investigated that traffic noise emission is mainly con- stituted by the motors of trucks, buses and motorcycles as well as brake. In this paper, two methods of traffic noise reduction on the indoor sound environment and comfort are carried out to study and compare the residential buildings adjacent to heavy traffic roadway in a city. One is to install noise barriers on the two sides of the roadway, which consist of sound-proof glass and plas- tic materials. The effect of sound-insulation of this method is heavily dependent on the relative distance between the noise bar- rier and indoors. A reduction of sound with an average pressure level of 2–15dB is achieved on the places behind and under the noise barrier. However, for the equivalent of noise barrier height, the noise reduction effect is little. As for the places of higher than the noise barrier, the traffic noise will be even strengthened by 3–7dB. Noise increment can be seen at the points of distance farther than 15m and height more than noise barrier; the noise reduction effect is not satisfactory or even worsened. In addition, not every location is appropriate to install the noise barrier along the heavy traffic roads. The other method of noise reduction for the buildings adjacent to heavy traffic is to install the airproof and soundproof windows, which is the conversion from natural venti- lation to mechanical ventilation. A reduction of sound with an average pressure level of 5dB to 17dB can be achieved compared with common glass windows, if adopting sound proof glass win- dows. These two methods are helpful to isolate high frequency noise but not for low frequency noise. For those frequency noises, installing thick and cotton curtain and porous carpet can only decrease 2.4–4.5dB, which hardly contributes to indoor sound comfort, so further study is demanded to cut down traffic noise, especially to cut down the low frequency noise.
基金Sponsored byt he Soft Science Subject of Chongqing Committee of Science &Technology(2006cc07)
文摘The definition of pillar industry is stated and its indicators, including the proportion of added value in the GDP, the degree of industry correlation, the income elasticity of demand, and the growth rate of employment will be discussed. And then index weighing is determined based on the degree of importance. The result of the quantitative analysis of real estate industry in Chongqing suggests that its first three evaluating indicators live up to the index requirement of a pillar industry while its degree of industry correlation is not satisfactory. An overall evaluation indicates that the real estate industry in Chongqing meets the requirements of pillar industry.
文摘The incorrect disposal of the waste generated in the municipalities contributes to water and soil contamination,resulting in a real concern in order to find an adequate disposal as well as obtain by-products that can be used to reduce CO2 emissions.Anaerobic digestion turns out to be the most efficient treatment,both in environmental and economic terms.The objective of this study is to evaluate the anaerobic co-digestion process in phases as an alternative for the treatment of municipal waste:sludge from water treatment plants and the biodegradable part of Municipal Solid Waste(MSW),for three HRTs(Hydraulic Retention Times).Testing results show up a max elimination of 70.68%in VS(Volatile Solids)and 74.01%in COD(Chemical Oxygen Demand).With these percentages of elimination on average,15.96 L/d of biogas was produced,for each kg of COD eliminated 0.56 m3 of biogas was produced and for each kg of SV 0.85 m3 and methane of 50.10%.
文摘The world has experienced 3 Industrial Revolutions.Right now,we are at the beginning of the 4th Industrial Revolution.4.0 Revolution is based on the digital revolution,characterized by the increasingly popular internet and mobile,by smaller and more powerful semiconductors at cheaper price and by Artificial Intelligence.Digital technologies with computer hardware,software and networks are becoming more and more complex,more integrated,thus transforming society.Faced with the unprecedented impact of the 4.0 Revolution,depending on the size of the economy and the level of technology,countries around the world have policies to adapt,catch up and take advantage of the achievements of the revolution.This revolution serves the sustainable development of our country.This article summarizes the policies of some countries such as Germany,the United States,Japan,Singapore,Republic of Korea,India,China,Taiwan,...under the impact of the 4.0 Revolution;thereby drawing lessons for Vietnam in the process of implementing the 4.0 Revolution to avoid negative impacts,take advantage of the pre-eminence of the revolution in socio-economic development.
文摘The implementation of modular multilevel converters(MMC)in an electric ship to create a medium voltage direct current(MVDC)energy conversion system that is efficient,small,dependable,and easily scalable has garnered considerable interest.In this research,an improved two-step nearest level control(E-NLC)is presented for MMC with a three-level submodule(3L-SM)as the rectifier of the electric ship power generation units in order to ease the economical and reliable operation of MMCs in MVDC systems.To achieve DC fault-clearing capability,the use of MMC with 3L-SM minimizes the number of switching devices when compared to the regular MMC topology.The suggested E-NLC scheme aims to reduce total harmonic distortion(THD)and achieve the nearest zero common mode voltage(CMV).The output voltage vector of the three phases is tuned using eight candidate vectors capable of suppressing CMV rather than the nearest-level vector,and the rounding function is modified to improve harmonic performance by increasing the approximation between stepped and modulated waves.The generator-connected MMC with THD reduction and CMV elimination maximizes the mover's protection in the generating unit of the electric ship's MVDC system.Simulation and experiment results validate the efficacy of the suggested approach with respect to steady-state and dynamic-state performance.
基金supported by grant from the National"95"Scientific and Technological Research Project in China(No.96-906-05-01).
文摘Background:Areal bone mineral density(aBMD)applied for osteoporosis diagnosis unavoidably results in the missingdiagnosis in patients with large bones and misdiagnosis in those with small bones.Therefore,we try to find a new adjusted index of bone mineral content(BMC)to make up shortcomings of aBMD in osteoporosis diagnosis.Methods:In this multi-center epidemiological study,BMC and aBMD of lumbar spines(n=5510)and proximal femurs(n=4710)were measured with dual energy X-ray absorptiometry(DXA).We analyzed the correlation between the bone mass and body weight in all subjects including four age groups(<19 years,20-39 years,40-49 years,>50 years).And then the body weight was used for standardizing BMC(named wBMC)and applied for the epidemiological analysis of osteoporosis?Results:The correlation of body weight and BMC is 0.839 to 0.931 of lumbar vertebra 1-4(Li_4),and 0.71 to 0.95 of femoral neck in different age groups.When aBMD was applied for diagnosing osteoporosis,the prevalence was 7.55%,16.39%,and 25.83%in patients with a high,intermediate,and low body weight respectively.However,the prevalence was 21.8%,18.03%,and 11.64%by wBMC applied for diagnosing osteoporosis.Moreover,the prevalence of osteoporosis increased by 3.76%by wBMC with the body weight increased by 5 kg.The prevalence decreased by 1.94%when the body weight decreased by 5 kg.Conclusions:wBMC can reduce the missed diagnosis in patients with large body weight and reduce misdiagnosis in those with small body weight.Including children,wBMC may be feasible for osteoporosis diagnosis individuals at any age.
