l-Methyl-3-ethyl imidazolium bromide[meim]Br/basic alumina（Al2O3） has been found to promote the cyclocondensation of chloroacetone/chloroethyl acetate with salicylaldehydes under conventional as well as microwave ir...l-Methyl-3-ethyl imidazolium bromide[meim]Br/basic alumina（Al2O3） has been found to promote the cyclocondensation of chloroacetone/chloroethyl acetate with salicylaldehydes under conventional as well as microwave irradiation to yield benzofuran derivatives.展开更多
An improved shooting method was presented for solving the natural convention boundary layer equations, with a coupling of the velocity field to the temperature field. The numerical results are consistent with the appr...An improved shooting method was presented for solving the natural convention boundary layer equations, with a coupling of the velocity field to the temperature field. The numerical results are consistent with the approximate solution obtained by former researchers.展开更多
The conventional pseudo-dynamic(CPD)and modified pseudo-dynamic(MPD)methods are invoked to obtain the seismic bearing capacity of strip foundations using the limit equilibrium method,with a two-wedge failure mechanism...The conventional pseudo-dynamic(CPD)and modified pseudo-dynamic(MPD)methods are invoked to obtain the seismic bearing capacity of strip foundations using the limit equilibrium method,with a two-wedge failure mechanism.A spectral version of the conventional pseudo-dynamic method(SPD)is also invoked by considering the ground motion amplification factor,to be a function of the non-dimensional frequencyλ/B and soil damping.Numeric analyses show that bearing capacity results obtained by the MPD and SPD methods are generally consistent.Both experience the same general reduction in bearing capacity with the increase ofλ/B,with successive ups and downs corresponding to soil′s natural frequencies.For 5<λ/B<10,SPD and MPD results fluctuated between falling above and below CPD results.Forλ/B<2.5,SPD and MPD results were consistent with attenuation of the shear wave,while for 10<λ/B,amplification was exhibited.Results obtained by the CPD method monotonically decrease,due to the fact that CPD fails to inherently consider site effects and damping,and instead and relies on a single factor to consider the ground motion amplification.展开更多
Fire effects can be one of the most harmful conditions that any building may experience throughout its service life. Developing practical protection methods and concepts against potential fire disasters in buildings h...Fire effects can be one of the most harmful conditions that any building may experience throughout its service life. Developing practical protection methods and concepts against potential fire disasters in buildings has been an important consideration in design of buildings in recent decades. Rapid developments in technology have heightened the demand for new and innovative fire protection systems in comparison with conventional and traditional methods. Such a need for new technologies is in particular of greater importance when it comes to existing buildings. Retrofitting an existing building for fire safety is a greater challenge compared with designing a new building using materials and components that have more desirable and superior fire rating to begin with. Furthermore, strategies to design a new building that includes state-of-the-art fire safety features are also different from solutions that may be more suitable for retrofitting an existing building. This paper presents a review of the literature concerning conventional and new or innovative retrofitting methods for fire safety of buildings. Advantages and disadvantages of different fire protection devices and methods as available and understood from the literature are mentioned. Study of fire safety systems shows that each has its drawbacks. Comparison of the results shows that disadvantages of a solitary system for retrofitting against fire can be improved by using a combination of several fire safety concepts or methods simultaneously.展开更多
Statistical distributions are used to model wind speed,and the twoparameters Weibull distribution has proven its effectiveness at characterizing wind speed.Accurate estimation of Weibull parameters,the scale(c)and sha...Statistical distributions are used to model wind speed,and the twoparameters Weibull distribution has proven its effectiveness at characterizing wind speed.Accurate estimation of Weibull parameters,the scale(c)and shape(k),is crucial in describing the actual wind speed data and evaluating the wind energy potential.Therefore,this study compares the most common conventional numerical(CN)estimation methods and the recent intelligent optimization algorithms(IOA)to show how precise estimation of c and k affects the wind energy resource assessments.In addition,this study conducts technical and economic feasibility studies for five sites in the northern part of Saudi Arabia,namely Aljouf,Rafha,Tabuk,Turaif,and Yanbo.Results exhibit that IOAs have better performance in attaining optimal Weibull parameters and provided an adequate description of the observed wind speed data.Also,with six wind turbine technologies rating between 1 and 3MW,the technical and economic assessment results reveal that the CN methods tend to overestimate the energy output and underestimate the cost of energy($/kWh)compared to the assessments by IOAs.The energy cost analyses show that Turaif is the windiest site,with an electricity cost of$0.016906/kWh.The highest wind energy output is obtained with the wind turbine having a rated power of 2.5 MW at all considered sites with electricity costs not exceeding$0.02739/kWh.Finally,the outcomes of this study exhibit the potential of wind energy in Saudi Arabia,and its environmental goals can be acquired by harvesting wind energy.展开更多
文摘l-Methyl-3-ethyl imidazolium bromide[meim]Br/basic alumina（Al2O3） has been found to promote the cyclocondensation of chloroacetone/chloroethyl acetate with salicylaldehydes under conventional as well as microwave irradiation to yield benzofuran derivatives.
基金The work is financially supported by the National Natural Science Foundations of China (No.50476083).
文摘An improved shooting method was presented for solving the natural convention boundary layer equations, with a coupling of the velocity field to the temperature field. The numerical results are consistent with the approximate solution obtained by former researchers.
文摘The conventional pseudo-dynamic(CPD)and modified pseudo-dynamic(MPD)methods are invoked to obtain the seismic bearing capacity of strip foundations using the limit equilibrium method,with a two-wedge failure mechanism.A spectral version of the conventional pseudo-dynamic method(SPD)is also invoked by considering the ground motion amplification factor,to be a function of the non-dimensional frequencyλ/B and soil damping.Numeric analyses show that bearing capacity results obtained by the MPD and SPD methods are generally consistent.Both experience the same general reduction in bearing capacity with the increase ofλ/B,with successive ups and downs corresponding to soil′s natural frequencies.For 5<λ/B<10,SPD and MPD results fluctuated between falling above and below CPD results.Forλ/B<2.5,SPD and MPD results were consistent with attenuation of the shear wave,while for 10<λ/B,amplification was exhibited.Results obtained by the CPD method monotonically decrease,due to the fact that CPD fails to inherently consider site effects and damping,and instead and relies on a single factor to consider the ground motion amplification.
文摘Fire effects can be one of the most harmful conditions that any building may experience throughout its service life. Developing practical protection methods and concepts against potential fire disasters in buildings has been an important consideration in design of buildings in recent decades. Rapid developments in technology have heightened the demand for new and innovative fire protection systems in comparison with conventional and traditional methods. Such a need for new technologies is in particular of greater importance when it comes to existing buildings. Retrofitting an existing building for fire safety is a greater challenge compared with designing a new building using materials and components that have more desirable and superior fire rating to begin with. Furthermore, strategies to design a new building that includes state-of-the-art fire safety features are also different from solutions that may be more suitable for retrofitting an existing building. This paper presents a review of the literature concerning conventional and new or innovative retrofitting methods for fire safety of buildings. Advantages and disadvantages of different fire protection devices and methods as available and understood from the literature are mentioned. Study of fire safety systems shows that each has its drawbacks. Comparison of the results shows that disadvantages of a solitary system for retrofitting against fire can be improved by using a combination of several fire safety concepts or methods simultaneously.
基金The author extends his appreciation to theDeputyship forResearch&Innovation,Ministry of Education,Saudi Arabia for funding this research work through the Project Number(QUIF-4-3-3-33891)。
文摘Statistical distributions are used to model wind speed,and the twoparameters Weibull distribution has proven its effectiveness at characterizing wind speed.Accurate estimation of Weibull parameters,the scale(c)and shape(k),is crucial in describing the actual wind speed data and evaluating the wind energy potential.Therefore,this study compares the most common conventional numerical(CN)estimation methods and the recent intelligent optimization algorithms(IOA)to show how precise estimation of c and k affects the wind energy resource assessments.In addition,this study conducts technical and economic feasibility studies for five sites in the northern part of Saudi Arabia,namely Aljouf,Rafha,Tabuk,Turaif,and Yanbo.Results exhibit that IOAs have better performance in attaining optimal Weibull parameters and provided an adequate description of the observed wind speed data.Also,with six wind turbine technologies rating between 1 and 3MW,the technical and economic assessment results reveal that the CN methods tend to overestimate the energy output and underestimate the cost of energy($/kWh)compared to the assessments by IOAs.The energy cost analyses show that Turaif is the windiest site,with an electricity cost of$0.016906/kWh.The highest wind energy output is obtained with the wind turbine having a rated power of 2.5 MW at all considered sites with electricity costs not exceeding$0.02739/kWh.Finally,the outcomes of this study exhibit the potential of wind energy in Saudi Arabia,and its environmental goals can be acquired by harvesting wind energy.
