A high resolution, nonhydrostatic, three dimensional diagnostic PBL model over small scale concave terrain was established in this paper. A two dimensional prognostic model was developed based on the diagnostic mo...A high resolution, nonhydrostatic, three dimensional diagnostic PBL model over small scale concave terrain was established in this paper. A two dimensional prognostic model was developed based on the diagnostic model. The hydrostatic approximation was abandoned and the simple energy ( E e ) closure scheme was used in both models. Using the two models, characteristics of PBL structure and its evolution were fully studied. The main characteristic of the PBL is the circulation, and it fairly affects the distribution of the pollutant in the pit.展开更多
This study presents a numerical multi-scale simulation framework which is extended to accommodate hybrid simulation （numerical-experimental integration）. The framework is enhanced with a standardized data exchange f...This study presents a numerical multi-scale simulation framework which is extended to accommodate hybrid simulation （numerical-experimental integration）. The framework is enhanced with a standardized data exchange format and connected to a generalized controller interface program which facilitates communication with various types of laboratory equipment and testing configurations. A small-scale experimental program was conducted using a six degree-of-freedom hydraulic testing equipment to verify the proposed framework and provide additional data for small-scale testing of shear- critical reinforced concrete structures. The specimens were tested in a multi-axial hybrid simulation manner under a reversed cyclic loading condition simulating earthquake forces. The physical models were 1/3.23-scale representations of a beam and two columns. A mixed-type modelling technique was employed to analyze the remainder of the structures. The hybrid simulation results were compared against those obtained from a large-scale test and finite element analyses. The study found that if precautions are taken in preparing model materials and if the shear-related mechanisms are accurately considered in the numerical model, small-scale hybrid simulations can adequately simulate the behaviour of shear-critical structures. Although the findings of the study are promising, to draw general conclusions additional test data are required.展开更多
The construction industry in most developing economies is dominated heavily by small and medium scale enterprises. These construction enterprises need to thrive in an extremely competitive business environment. Conver...The construction industry in most developing economies is dominated heavily by small and medium scale enterprises. These construction enterprises need to thrive in an extremely competitive business environment. Conversely, most of these small and medium scale construction enterprises (SMSCE) are fraught with a plethora of barriers that inhibit and threaten their growth and survival. This research sought to evaluate the critical barriers that affect the growth of SMSCEs in the Ghanaian Construction Industry. The quantitative research method was adopted using a structured questionnaire with variables that were identified through a comprehensive literature review. The survey questionnaire was administered to 400 respondents comprising 250 SMSCEs, 100 Local Authority Engineers, and 50 Consultants to elicit data based on the identified variables. The major findings established by the study as barriers to the growth of SMSCEs in Ghana are largely structured as financial/fiscal barriers, business development barriers, technical/technological barriers, corruption barriers, knowledge management barriers, project acquisition barriers. A guiding framework should be developed based on the barriers identified to aid the growth and survival of SMSCEs in Ghana.展开更多
This paper investigates the socio-cultural challenges of the small-scale batik and tie-dye production and retailing industry in Ghana. The research is based on a qualitative research approach that employs interviews a...This paper investigates the socio-cultural challenges of the small-scale batik and tie-dye production and retailing industry in Ghana. The research is based on a qualitative research approach that employs interviews and observation for data collection. In all, sixteen (16) participants were sampled through purposive techniques. Data collected were transcribed, classified and analysed through thematic and descriptive analysis. The study found that family roles contradict the business role, pressure from family members, poor support from society members, some religious teachings, age, ethnicity and lifestyle of certain people among others. The study concludes that socio-cultural challenges have led to the collapse of most batik and tie-dye production and retailing sectors leaving thousands of Ghanaians jobless. It recommends among others that producers and retailers of batik and tie-dye must separate family roles from work responsibilities to enable them to perform effectively. Again, family members, parents and peers must desist from putting pressure on the entrepreneurs for freebies and the government must resource NBSSI, GEPA and GSB to have regular in-service training to batik and tie-dye producers and retailers to address poor financial management and technical challenges and also on product quality on the international market.展开更多
This study presents three kinds of skid-mounted plants, including single mixed refrigerant cycle (MRC), nitrogen expander cycle, and natural gas (NG) Claude cycle. Hysys simulation shows that single MRC is the most ef...This study presents three kinds of skid-mounted plants, including single mixed refrigerant cycle (MRC), nitrogen expander cycle, and natural gas (NG) Claude cycle. Hysys simulation shows that single MRC is the most efficient cycle among the three. The specific power of single MRC liquefiers is 1485 kJ/kg, 15% higher than that of large liquefaction process. Considering the recovery of stranded-gas, commercial analysis suggests that the initial cost of LNG plants ranging from 1 to 100 m3 /day can be paid back in 2 to 4 years.展开更多
The time evolution of the magnetic field aligned super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma, is studied with the help of the model simulation...The time evolution of the magnetic field aligned super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma, is studied with the help of the model simulation. A new version of the two-dimensional mathematical model, developed earlier in the Polar Geophysical Institute, is utilized to investigate the temporal history of the irregularity with circular cross section, created initially in the near-Earth plasma. The utilized model is based on a numerical solution of the Vlasov-Poisson system of equations, with the Vlasov equations describing the distribution functions of charged particles and the Poisson equation governing the self-consistent electric field. The results of simulation indicate that the mobility of the positive ions ought to influence essentially on the time evolution of the super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma.展开更多
文摘A high resolution, nonhydrostatic, three dimensional diagnostic PBL model over small scale concave terrain was established in this paper. A two dimensional prognostic model was developed based on the diagnostic model. The hydrostatic approximation was abandoned and the simple energy ( E e ) closure scheme was used in both models. Using the two models, characteristics of PBL structure and its evolution were fully studied. The main characteristic of the PBL is the circulation, and it fairly affects the distribution of the pollutant in the pit.
文摘This study presents a numerical multi-scale simulation framework which is extended to accommodate hybrid simulation （numerical-experimental integration）. The framework is enhanced with a standardized data exchange format and connected to a generalized controller interface program which facilitates communication with various types of laboratory equipment and testing configurations. A small-scale experimental program was conducted using a six degree-of-freedom hydraulic testing equipment to verify the proposed framework and provide additional data for small-scale testing of shear- critical reinforced concrete structures. The specimens were tested in a multi-axial hybrid simulation manner under a reversed cyclic loading condition simulating earthquake forces. The physical models were 1/3.23-scale representations of a beam and two columns. A mixed-type modelling technique was employed to analyze the remainder of the structures. The hybrid simulation results were compared against those obtained from a large-scale test and finite element analyses. The study found that if precautions are taken in preparing model materials and if the shear-related mechanisms are accurately considered in the numerical model, small-scale hybrid simulations can adequately simulate the behaviour of shear-critical structures. Although the findings of the study are promising, to draw general conclusions additional test data are required.
文摘The construction industry in most developing economies is dominated heavily by small and medium scale enterprises. These construction enterprises need to thrive in an extremely competitive business environment. Conversely, most of these small and medium scale construction enterprises (SMSCE) are fraught with a plethora of barriers that inhibit and threaten their growth and survival. This research sought to evaluate the critical barriers that affect the growth of SMSCEs in the Ghanaian Construction Industry. The quantitative research method was adopted using a structured questionnaire with variables that were identified through a comprehensive literature review. The survey questionnaire was administered to 400 respondents comprising 250 SMSCEs, 100 Local Authority Engineers, and 50 Consultants to elicit data based on the identified variables. The major findings established by the study as barriers to the growth of SMSCEs in Ghana are largely structured as financial/fiscal barriers, business development barriers, technical/technological barriers, corruption barriers, knowledge management barriers, project acquisition barriers. A guiding framework should be developed based on the barriers identified to aid the growth and survival of SMSCEs in Ghana.
文摘This paper investigates the socio-cultural challenges of the small-scale batik and tie-dye production and retailing industry in Ghana. The research is based on a qualitative research approach that employs interviews and observation for data collection. In all, sixteen (16) participants were sampled through purposive techniques. Data collected were transcribed, classified and analysed through thematic and descriptive analysis. The study found that family roles contradict the business role, pressure from family members, poor support from society members, some religious teachings, age, ethnicity and lifestyle of certain people among others. The study concludes that socio-cultural challenges have led to the collapse of most batik and tie-dye production and retailing sectors leaving thousands of Ghanaians jobless. It recommends among others that producers and retailers of batik and tie-dye must separate family roles from work responsibilities to enable them to perform effectively. Again, family members, parents and peers must desist from putting pressure on the entrepreneurs for freebies and the government must resource NBSSI, GEPA and GSB to have regular in-service training to batik and tie-dye producers and retailers to address poor financial management and technical challenges and also on product quality on the international market.
文摘This study presents three kinds of skid-mounted plants, including single mixed refrigerant cycle (MRC), nitrogen expander cycle, and natural gas (NG) Claude cycle. Hysys simulation shows that single MRC is the most efficient cycle among the three. The specific power of single MRC liquefiers is 1485 kJ/kg, 15% higher than that of large liquefaction process. Considering the recovery of stranded-gas, commercial analysis suggests that the initial cost of LNG plants ranging from 1 to 100 m3 /day can be paid back in 2 to 4 years.
文摘The time evolution of the magnetic field aligned super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma, is studied with the help of the model simulation. A new version of the two-dimensional mathematical model, developed earlier in the Polar Geophysical Institute, is utilized to investigate the temporal history of the irregularity with circular cross section, created initially in the near-Earth plasma. The utilized model is based on a numerical solution of the Vlasov-Poisson system of equations, with the Vlasov equations describing the distribution functions of charged particles and the Poisson equation governing the self-consistent electric field. The results of simulation indicate that the mobility of the positive ions ought to influence essentially on the time evolution of the super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma.
