Objective YAP1 plays a dual role as an oncogene and tumor suppressor gene in several tumors;differentiating between these roles may depend on the YAP1 phosphorylation pattern.The specific function of YAP1 in B cell ac...Objective YAP1 plays a dual role as an oncogene and tumor suppressor gene in several tumors;differentiating between these roles may depend on the YAP1 phosphorylation pattern.The specific function of YAP1 in B cell acute lymphoblastic leukemia(B-ALL),however,is currently unclear.Thus,in the present study,the role of YAP1 in B-ALL was investigated using relevant cell lines and patient datasets.Methods The effects of shRNA-mediated knockdown on YAP1 and LATS1 levels in the NALM6 and MOLT-4 cell lines were examined using Western blotting,quantitative real-time polymerase chain reaction,flow cytometry,immunostaining,and nude mouse subcutaneous tumorigenesis experiments.Gene expression levels of Hippo pathway-related molecules before and after verteporfin(VP)treatment were compared using RNA-Seq to identify significant Hippo pathway-related genes in NALM6 cells.Results Patients with ALL showing high YAP1 expression and low YAP1-Ser127 phosphorylation levels had worse prognoses than those with low YAP1 protein expression and high YAP1-Ser127 phosphorylation levels.YAP1-Ser127 phosphorylation levels were lower in NALM6 cells than in MOLT-4 and control cells;YAP1 was distributed in the nuclei in NALM6 cells.Knockdown of YAP1 inhibited MOLT-4 and NALM6 cell proliferation and arrested the NALM6 cell cycle in the G0/G1 phase.Before and after VP treatment,the expression of the upstream gene LATS1 was upregulated;its overexpression promoted YAP1-Ser127 phosphorylation.Further,YAP1 was distributed in the plasma.Conclusion LATS1 may downregulate YAP1-Ser127 phosphorylation and maintain B-ALL cell function;thus,VP,which targets this axis,may serve as a new therapeutic method for improving the outcomes for B-ALL patients.展开更多
The main objective of this research was to examine the suitability of aluminium alloy to design a piston of an internal combustion engine for improvement in weight and cost reduction. The piston was modelled using Aut...The main objective of this research was to examine the suitability of aluminium alloy to design a piston of an internal combustion engine for improvement in weight and cost reduction. The piston was modelled using Autodesk Inventor 2017 software. The modelled piston was then imported into Ansys for further analysis. Static structural and thermal analysis were carried out on the pistons of the four different materials namely: Al 413 alloy, Al 384 alloy, Al 390 alloy and Al332 alloy to determine the total deformation, equivalent Von Mises stress, maximum shear stress, and the safety factor. The results of the study revealed that, aluminium 332 alloy piston deformed less compared to the deformations of aluminium 390 alloy piston, aluminium 384 alloy piston and aluminium 413 alloy piston. The induced Von Mises stresses in the pistons of the four different materials were found to be far lower than the yield strengths of all the materials. Hence, all the selected materials including the implementing material have equal properties to withstand the maximum gas load. All the selected materials were observed to have high thermal conductivity enough to be able to withstand the operating temperature in the engine cylinders.展开更多
The research seeks to understand the effects of internal courtyards on thermal comfort conditions in compound houses in Ghana’s Tamale Metropolitan area.Internal courtyards are an integral part of the design of compo...The research seeks to understand the effects of internal courtyards on thermal comfort conditions in compound houses in Ghana’s Tamale Metropolitan area.Internal courtyards are an integral part of the design of compound houses in this location.Their inclusion in building designs is largely as a point of domestic activity such as cooking and cleaning and also for social interaction.However,a lot of interchanges in thermal conditions between structures and the outdoors take place within these internal courtyards.Various design details of the building will engender different thermal responses of the internal courtyard.This paper assesses thermal comfort in compound houses as against bungalow type houses in the Tamale Metropolis,Ghana by the application of the Predicted Percentage of Dissatisfied Persons(PPD)and Predicted Mean Votes(PMV)model.This prototype compares with the International Standards Organization(ISO)7730 and American Society of Heating,Refrigeration and Air-Conditioning Engineers(ASHRAE)Standard 55(estimated values between 23℃-26℃seen as the allowable temperatures).Ambient indoor conditions(dry bulb temperature and relative humidity)of five(5)buildings each from the two building typologies from were recorded over a period of ten calendar months.These ambient conditions were analyzed,consequently generating the Predicted Percentage of Dissatisfied Persons(PPD)and Predicted Mean Votes(PMV)recordings.The investigations uncovered relatively high PPD-PMV recordings relating to the Bungalow type buildings while the compound houses attune to the comfort zone.The Actual Mean Votes(AMV)of residents suggests the two building typologies are all rated comfortable however;the compound houses are rated above the bungalow type houses.展开更多
There is a perpetual problem of partial or complete roof collapse within the Tamale Metropolis and other parts of Ghana.This has become an issue of grave public concern since this menace affects both public buildings ...There is a perpetual problem of partial or complete roof collapse within the Tamale Metropolis and other parts of Ghana.This has become an issue of grave public concern since this menace affects both public buildings of all kinds(schools,offices,churches,mosque etc.)as well as domestic buildings.This research sets out to conduct comprehensive investigations into the nature of roof failures,causes,and effects and then propose remedial actions towards stemming the tide.The study employed the use of roof construction affirmation surveys,questionnaires,interviews and focus group discussions.Relevant information synthesized indicates that the roof type,construction materials,building type and environmental conditions are crucial causative factors.Major consequences of roof failures include damage to personal belongings and exposure to inclement weather conditions,the psychological trauma victims are subjected and pressure on incomes and living conditions as a result of the cost of repair or replacement of the roofs.It is recommended that expert advice be sought in checking maintenance requirements of existing roofs in the study area and also during the design and construction of new roofs.Tree planting programmes for this heavily deforested region should be encouraged.The use of green timber for roof construction must be replaced with well-seasoned ones.Proper construction detailing and placement openings buildings should be done so that wind flow during a windstorm is optimized.展开更多
Atmospheric CO_(2)concentrations are soaring due to the continued use of fossil fuels in energy production,an anthropogenic activity that is playing a leading role in global warming.Thus,research aimed at the capture ...Atmospheric CO_(2)concentrations are soaring due to the continued use of fossil fuels in energy production,an anthropogenic activity that is playing a leading role in global warming.Thus,research aimed at the capture and conversion of CO_(2)into value-added products,such as cyclic carbonates,is booming.While CO_(2)is an abundant,cheap,non-toxic,and readily accessible Cl feedstock,its thermodynamic stability necessitates the development of highly efficient catalysts that are able to promote chemical reactions under mild conditions.In this work,a novel mesoporous poly(ionic liquid)with dual active sites was synthesized through a facile method that involves co-polymerization,post-synthetic metalation,and supercritical CO_(2)drying.Due to a high density of nucleophilic and electrophilic sites,the as-prepared poly(ionic liquid),denoted as P2D-4BrBQA-Zn,offers excellent performance in a CO_(2)cycloaddition reaction using epichlorohydrin as the substrate(98.9%conversion and 96.9%selectivity).Moreover the reaction is carried out under mild,solvent-free,and additive-free conditions.Notably,P2D-4BrBQA-Zn also efficiently promotes the conversion of various other epoxide substrates into cyclic carbonates.Overall,the catalyst is found to have excellent substrate compatibility,stability,and recyclability.展开更多
The suspension coil spring is one of the most important components in a vehicle suspension system. Its primary function is to absorb the vibrational shocks that are occasioned by irregular road surface to provide the ...The suspension coil spring is one of the most important components in a vehicle suspension system. Its primary function is to absorb the vibrational shocks that are occasioned by irregular road surface to provide the vehicle with stability and ride comfort. The main objective of this study is to design a suspension coil spring made of structural steel for light duty vehicles with the aim of weight and cost reduction. This study was motivated by the government of Ghana’s actions to industrialise the automotive sector of the country through government policies and programs. The study made use of high carbon steel and low carbon steel as the control materials and structural steel as the implementing material. This was done to determine the suitability of structural steel for vehicle suspension coil spring. The study analysed parameters such as total deformation, equivalent Von Mises stress, maximum shear stress, and safety factor in the static structural analysis. The fatigue analysis also analysed parameters such as fatigue life and fatigue alternating stress. The results of the study revealed that the suspension spring made of structural steel has superior properties against all the parameters set for this study apart from deformation. The two control materials that are known for suspension coil spring design and manufacture have better properties to withstand deformation than the implementing material.展开更多
The connecting rod is one of the most important moving components in an internal combustion engine. The present work determined the possibility of using aluminium alloy 7075 material to design and manufacture a connec...The connecting rod is one of the most important moving components in an internal combustion engine. The present work determined the possibility of using aluminium alloy 7075 material to design and manufacture a connecting rod for weight optimisation without losing the strength of the connecting rod. It considered modal and thermal analyses to investigate the suitability of the material for connecting rod design. The parameters that were considered under the modal analysis were: total deformation, and natural frequency, while the thermal analysis looked at the temperature distribution, total heat flux and directional heat flux of the four connecting rods made with titanium alloy, grey cast iron, structural steel and aluminium 7075 alloy respectively. The connecting rod was modelled using Autodesk inventor2017 software using the calculated parameters. The steady-state thermal analysis was used to determine the induced heat flux and directional heat flux. The study found that Aluminium 7075 alloy deformed more than the remaining three other materials but has superior qualities in terms of vibrational natural frequency, total heat flux and lightweight compared to structural steel, grey cast iron and titanium alloy.展开更多
Both farmers and traders benefit from trade networking, which is crucial for the local economy. Therefore, it is crucial to understand how these networks operate, and how they can be managed more effectively. Througho...Both farmers and traders benefit from trade networking, which is crucial for the local economy. Therefore, it is crucial to understand how these networks operate, and how they can be managed more effectively. Throughout this study, we examine the economic networks formed between farmers and traders through the trade of food products. These networks are analyzed from the perspective of their structure and the factors that influence their development. Using data from 18 farmers and 15 traders, we applied exponential random graph models. The results of our study showed that connectivity, Popularity Spread, activity spread, good transportation systems, and high yields all affected the development of networks. Therefore, farmers’ productivity and high market demand can contribute to local food-crop trade. The network was not affected by reciprocity, open markets, proximity to locations, or trade experience of actors. Policy makers should consider these five factors when formulating policies for local food-crop trade. Additionally, local actors should be encouraged to use these factors to improve their network development. However, it is important to note that these factors alone cannot guarantee success. Policy makers and actors must also consider other factors such as legal frameworks, economic policies, and resource availability. Our approach can be used in future research to determine how traders and farmers can enhance productivity and profit in West Africa. This study addresses a research gap by examining factors influencing local food trade in a developing country.展开更多
Laser shock peening is a modernized surface enhancement performed methodically to improve fatigue life, enhance the hardness of the material and make coarse grains flat under the superficial layer. In this current stu...Laser shock peening is a modernized surface enhancement performed methodically to improve fatigue life, enhance the hardness of the material and make coarse grains flat under the superficial layer. In this current study, the effect of varying optimized multiple laser shock peening (LSP) is studied on the surface integrity, microhardness, and mechanical properties. The results show that the LSP-treated specimens have visible signs of valleys, wavy and varying height distribution as well as dimples. However, the presence of non-uniformity and sharp protrusions was detected from the superficiality of the as-received specimen and this was so because of the SiC abrasive material used to polish the superficial layer of the specimen before the test experiment. Prior to LSP, the surface roughness was 2 μm, however, after LSP the roughness increased to 4 μm, 6 μm and 17 μm for 1, 2, and 4 impacts, respectively. High-density dislocation can also be observed close to the grain boundary because the grain boundary prevents the migration of dislocation which could lead to dislocation walls and dislocation tangles. The increase in impacts decrease the average grain size, nevertheless, the micro-strain increased after multiple impacts. Furthermore, coarse grains after LSP were transformed into finer grains. The increase in the number of impacts increases the micro-strain likewise the full-width half maximum (FWHM). Finally, the increase in microhardness increases as the LSP impacts increase.展开更多
This study aims at developing a Knowledge Management Implementation Framework for adoption by firms in the Ghanaian construction industry. Recent developments in the field of Knowledge management in the construction s...This study aims at developing a Knowledge Management Implementation Framework for adoption by firms in the Ghanaian construction industry. Recent developments in the field of Knowledge management in the construction sector have led to a renewed competition in driving organizational performance. However, the construction industry in Ghana lacks a knowledge management implementation framework that addresses the needs of the Ghanaian construction supply chain while a comprehensive approach to managing knowledge remains nebulous. The study adopted an extensive literature review of existing knowledge management models to provide the basis for the development of the proposed framework for Ghana. The proposed knowledge management implementation framework was subjected to testing and validation by project managers drawn from nineteen indigenous construction firms in Ghana. The technology acceptance model (TAM) was used as the criteria to validate the proposed knowledge management implementation framework. The proposed Guribie & Tengan knowledge management implementation framework was perceived to be useful, and easy to use and the intention to adopt and use was high among indigenous Ghanaian construction firms. The study recommends further validation using wider population to enhance the efficacy of the framework for wider industry acceptance to enhance organizational competitiveness and performance delivery.展开更多
Understanding the weldability of steel in relation to the use of carbon equivalent is very necessary </span><span style="white-space:normal;font-family:"">for</span><span style...Understanding the weldability of steel in relation to the use of carbon equivalent is very necessary </span><span style="white-space:normal;font-family:"">for</span><span style="white-space:normal;font-family:""> the welding industry. The study was poised to unearth the fundamentals of carbon equivalent as applied in evaluating the weldability of steel. The study used </span><span style="white-space:normal;font-family:"">a </span><span style="white-space:normal;font-family:"">two-stage design approach to address the problem of carbon equivalence weldability of steel, thus, survey and experimental. Two different steels were tested to ascertain their chemical composition which could inform carbon equivalent calculation, and the results revealed microalloy and low alloy steels respectively. In subjecting the microalloy steel to carbon equivalent analyses of the AWS and IIW coefficients;revealed a value (CEV) = 0.11 each, suggesting that this microalloy steel has excellent weldability;no preheat</span><span style="white-space:normal;font-family:"">ing</span><span style="white-space:normal;font-family:""> is required. A successful welding operation on this steel does not depend on preheat</span><span style="white-space:normal;font-family:"">ing</span><span style="white-space:normal;font-family:"">.<b> </b>Also</span><span style="white-space:normal;font-family:"">,</span><span style="white-space:normal;font-family:""> the average results of the low alloy steel revealed a value (CEV) = 0.37 and 0.32 respectively, suggesting that this type of steel has very good weldability and may require </span><span style="white-space:normal;font-family:"">to </span><span style="white-space:normal;font-family:"">preheat. It is recommended that welders have </span><span style="white-space:normal;font-family:"">a </span><span style="white-space:normal;font-family:"">general idea about the weldability of steel with regard to carbon equivalent calculation. In addition</span><span style="white-space:normal;font-family:"">,</span><span style="white-space:normal;font-family:""> they should understand the chemical compositions of steels they are dealing with.展开更多
Estimation methods have over the years been a problem for Statistician especially in sectors that have to do with Hidden/Hard-to-Reach population. In this paper, a regression model was derived for Elusive/Hard-to-Reac...Estimation methods have over the years been a problem for Statistician especially in sectors that have to do with Hidden/Hard-to-Reach population. In this paper, a regression model was derived for Elusive/Hard-to-Reach/Hidden populations. This was achieved by modelling the Multiplicity Estimator given by Birnbaum and Sirken (1965) into a regression model. The paper also gave the least-squares estimation of the unknown parameters β0 and β1, and σ2.展开更多
Academia and industry research enables researchers to conduct research projects that are more relevant to current business practices and context. Although, several construction research works have been done by the aca...Academia and industry research enables researchers to conduct research projects that are more relevant to current business practices and context. Although, several construction research works have been done by the academics in the tertiary institutions in Ghana, it is sad to know that, a large number of these research works have not moved from the pure stage to the applied stage. This study seeks to establish the imperative of academia and industry collaboration in building research in Ghana. A total of 116 construction practising professionals consisting of Ghana Institute of Construction (GIOC) corporate members (QS, Architects, Engineers and so on) from the industry, and academics from tertiary academic institutions (That’s, Lecturers from KNUST and UEW) that run postgraduate construction programmes in Ghana as at February 2016 constituted the respondents for this study. Census and systematic sampling techniques were used for the sampled population. Descriptive statistics was employed in the data analysis for the mean and standard deviation (SD) score values of variables. The most imperatives for academia and industry collaboration were found to be: ensuring research findings solve socio-economic and development problems, the intermittent collapse of buildings, support for the local industries to produce quality materials locally to feed the construction industry, proper contract documentations and administration. This research would bring to light the urgent issues in the construction industry that calls for greater collaboration between the academia and industry in Ghana. It reveals a deeper understanding on the need for collaborative research in the Ghanaian construction industry, by providing the most imperatives to academia-industry collaborative research in Ghana.展开更多
The structural equation model (SEM) concept is generally influenced by the presence of outliers and controlling variables. To a very large extent, this could have consequential effects on the parameters and the model ...The structural equation model (SEM) concept is generally influenced by the presence of outliers and controlling variables. To a very large extent, this could have consequential effects on the parameters and the model fitness. Though previous researches have studied outliers and controlling observations from various perspectives including the use of box plots, normal probability plots, among others, the use of uniform horizontal QQ plot is yet to be explored. This study is, therefore, aimed at applying uniform QQ plots to identifying outliers and possible controlling observations in SEM. The results showed that all the three methods of estimators manifest the ability to identify outliers and possible controlling observations in SEM. It was noted that the Anderson-Rubin estimator of QQ plot showed a more efficient or visual display of spotting outliers and possible controlling observations as compared to the other methods of estimators. Therefore, this paper provides an efficient way identifying outliers as it fragments the data set.展开更多
Jet breakup and dispersion from impact sprinkler are mainly influenced by the configurations of nozzle and dispersion device.Based on the structure,different types of nozzles were designed and tested with a pointed ti...Jet breakup and dispersion from impact sprinkler are mainly influenced by the configurations of nozzle and dispersion device.Based on the structure,different types of nozzles were designed and tested with a pointed tip dispersion device under low pressure conditions.Experiments were performed using High-Speed Photographic technique,and Matlab computation program was established and applied to determine the initial jet breakup length and angle of dispersion from the nozzles.The sprinkler range decreased with the increase in diameter of nozzle,and the largest range of 15.1 m was produced from sprinkler with 6 mm nozzle size under a pressure of 150 kPa.The angle of dispersion decreased with the increase of jet velocity,the spray coverage from sprinkler with 6 mm nozzle size was 1478 mm under 150 kPa,and was not statistically different when the pressure was increased.A new range formula was established for sprinkler with dispersion device through curve fitting of the parameters of initial jet breakup length,angle of dispersion,nozzle size and working pressure.The new formula was reliable for calculating range with a relative error less than 3%.Since the formula is based on the angle of dispersion,it could be useful to estimate uniformity of water distribution in sprinkler irrigated fields.展开更多
One way to adapt to the trend towards low-energy and to improve the hydraulic performance of the impact sprinkler under a low pressure condition is by means of a fixed water dispersion device.A fixed dispersion device...One way to adapt to the trend towards low-energy and to improve the hydraulic performance of the impact sprinkler under a low pressure condition is by means of a fixed water dispersion device.A fixed dispersion device disperses jet flow from the nozzle continuously.The shape of the tip,impact angle(θ),diameter(D),and depth in the jet flow(d)have significant influence on the hydraulic performance.In this study,the hydraulic performance characteristics of impact sprinkler as affected by the fixed water dispersion device were studied under indoor conditions.Radial water distributions from the sprinkler were obtained by experiments for the fixed water dispersion devices.MATLAB was used to transform the radial data into net data,and the uniformities were simulated in a square layout from 1 to 2 times the range(R).The droplet size distributions from the fixed water dispersion devices were measured by a laser precipitation monitor(LPM).Results showed that the range increased with the increase of pressure,and the sprinkler with type C_(2) produced a rectangular-shaped water distribution pattern,while the range was maintained.A maximum uniformity of 71.56%,75.56%,77.23%,73.32%,78.88%and 86.67%was found for types A1,B1,C1,A2,B2,and C_(2),respectively under a pressure of 200 kPa.The uniformity from the sprinkler using type C_(2) surpassed 80%,while type C1 fell below.Droplet sizes from type C_(2) was best,and the mean droplet diameter decreased with the increase of pressure.Hence,type C_(2) can be selected for further optimization of the design features to improve the hydraulic performance of the impact sprinkler under low pressure conditions.展开更多
Water saving is an essential part of sprinkler irrigation owing to the impact of climate change and rising energy costs.This review highlights the technologies that are emerging in sprinkler irrigation to optimize cro...Water saving is an essential part of sprinkler irrigation owing to the impact of climate change and rising energy costs.This review highlights the technologies that are emerging in sprinkler irrigation to optimize crop production.While there have been notable advances in irrigation,the continued progress has occurred by the combination of current status with the postulation of new ideas such as conversion of high-pressure sprinkler to low-pressure ones,incorporation of smart controllers in sprinkler irrigation systems.To enhance the adoption of these technologies,research on the dispersion device is needed to improve the performance of impact sprinklers to efficiently operate at low-pressure conditions.It is also important to study how water savings estimates based on water use,irrigated area,longevity of saving,and level of wasteful irrigation prior to the retrofit obtained from field trials can be extrapolated to other areas with different conditions.Research in the development of optimized method for irrigation scheduling is necessary.This review emphasizes that the status of technologies should be considered a continuum,building on earlier knowledge and progress,and hopefully leading toward optimized crop production in sprinkler irrigated areas.展开更多
文摘Objective YAP1 plays a dual role as an oncogene and tumor suppressor gene in several tumors;differentiating between these roles may depend on the YAP1 phosphorylation pattern.The specific function of YAP1 in B cell acute lymphoblastic leukemia(B-ALL),however,is currently unclear.Thus,in the present study,the role of YAP1 in B-ALL was investigated using relevant cell lines and patient datasets.Methods The effects of shRNA-mediated knockdown on YAP1 and LATS1 levels in the NALM6 and MOLT-4 cell lines were examined using Western blotting,quantitative real-time polymerase chain reaction,flow cytometry,immunostaining,and nude mouse subcutaneous tumorigenesis experiments.Gene expression levels of Hippo pathway-related molecules before and after verteporfin(VP)treatment were compared using RNA-Seq to identify significant Hippo pathway-related genes in NALM6 cells.Results Patients with ALL showing high YAP1 expression and low YAP1-Ser127 phosphorylation levels had worse prognoses than those with low YAP1 protein expression and high YAP1-Ser127 phosphorylation levels.YAP1-Ser127 phosphorylation levels were lower in NALM6 cells than in MOLT-4 and control cells;YAP1 was distributed in the nuclei in NALM6 cells.Knockdown of YAP1 inhibited MOLT-4 and NALM6 cell proliferation and arrested the NALM6 cell cycle in the G0/G1 phase.Before and after VP treatment,the expression of the upstream gene LATS1 was upregulated;its overexpression promoted YAP1-Ser127 phosphorylation.Further,YAP1 was distributed in the plasma.Conclusion LATS1 may downregulate YAP1-Ser127 phosphorylation and maintain B-ALL cell function;thus,VP,which targets this axis,may serve as a new therapeutic method for improving the outcomes for B-ALL patients.
文摘The main objective of this research was to examine the suitability of aluminium alloy to design a piston of an internal combustion engine for improvement in weight and cost reduction. The piston was modelled using Autodesk Inventor 2017 software. The modelled piston was then imported into Ansys for further analysis. Static structural and thermal analysis were carried out on the pistons of the four different materials namely: Al 413 alloy, Al 384 alloy, Al 390 alloy and Al332 alloy to determine the total deformation, equivalent Von Mises stress, maximum shear stress, and the safety factor. The results of the study revealed that, aluminium 332 alloy piston deformed less compared to the deformations of aluminium 390 alloy piston, aluminium 384 alloy piston and aluminium 413 alloy piston. The induced Von Mises stresses in the pistons of the four different materials were found to be far lower than the yield strengths of all the materials. Hence, all the selected materials including the implementing material have equal properties to withstand the maximum gas load. All the selected materials were observed to have high thermal conductivity enough to be able to withstand the operating temperature in the engine cylinders.
文摘The research seeks to understand the effects of internal courtyards on thermal comfort conditions in compound houses in Ghana’s Tamale Metropolitan area.Internal courtyards are an integral part of the design of compound houses in this location.Their inclusion in building designs is largely as a point of domestic activity such as cooking and cleaning and also for social interaction.However,a lot of interchanges in thermal conditions between structures and the outdoors take place within these internal courtyards.Various design details of the building will engender different thermal responses of the internal courtyard.This paper assesses thermal comfort in compound houses as against bungalow type houses in the Tamale Metropolis,Ghana by the application of the Predicted Percentage of Dissatisfied Persons(PPD)and Predicted Mean Votes(PMV)model.This prototype compares with the International Standards Organization(ISO)7730 and American Society of Heating,Refrigeration and Air-Conditioning Engineers(ASHRAE)Standard 55(estimated values between 23℃-26℃seen as the allowable temperatures).Ambient indoor conditions(dry bulb temperature and relative humidity)of five(5)buildings each from the two building typologies from were recorded over a period of ten calendar months.These ambient conditions were analyzed,consequently generating the Predicted Percentage of Dissatisfied Persons(PPD)and Predicted Mean Votes(PMV)recordings.The investigations uncovered relatively high PPD-PMV recordings relating to the Bungalow type buildings while the compound houses attune to the comfort zone.The Actual Mean Votes(AMV)of residents suggests the two building typologies are all rated comfortable however;the compound houses are rated above the bungalow type houses.
文摘There is a perpetual problem of partial or complete roof collapse within the Tamale Metropolis and other parts of Ghana.This has become an issue of grave public concern since this menace affects both public buildings of all kinds(schools,offices,churches,mosque etc.)as well as domestic buildings.This research sets out to conduct comprehensive investigations into the nature of roof failures,causes,and effects and then propose remedial actions towards stemming the tide.The study employed the use of roof construction affirmation surveys,questionnaires,interviews and focus group discussions.Relevant information synthesized indicates that the roof type,construction materials,building type and environmental conditions are crucial causative factors.Major consequences of roof failures include damage to personal belongings and exposure to inclement weather conditions,the psychological trauma victims are subjected and pressure on incomes and living conditions as a result of the cost of repair or replacement of the roofs.It is recommended that expert advice be sought in checking maintenance requirements of existing roofs in the study area and also during the design and construction of new roofs.Tree planting programmes for this heavily deforested region should be encouraged.The use of green timber for roof construction must be replaced with well-seasoned ones.Proper construction detailing and placement openings buildings should be done so that wind flow during a windstorm is optimized.
基金financial support from the National Natural Science Foundation of China(22078274,21903066)。
文摘Atmospheric CO_(2)concentrations are soaring due to the continued use of fossil fuels in energy production,an anthropogenic activity that is playing a leading role in global warming.Thus,research aimed at the capture and conversion of CO_(2)into value-added products,such as cyclic carbonates,is booming.While CO_(2)is an abundant,cheap,non-toxic,and readily accessible Cl feedstock,its thermodynamic stability necessitates the development of highly efficient catalysts that are able to promote chemical reactions under mild conditions.In this work,a novel mesoporous poly(ionic liquid)with dual active sites was synthesized through a facile method that involves co-polymerization,post-synthetic metalation,and supercritical CO_(2)drying.Due to a high density of nucleophilic and electrophilic sites,the as-prepared poly(ionic liquid),denoted as P2D-4BrBQA-Zn,offers excellent performance in a CO_(2)cycloaddition reaction using epichlorohydrin as the substrate(98.9%conversion and 96.9%selectivity).Moreover the reaction is carried out under mild,solvent-free,and additive-free conditions.Notably,P2D-4BrBQA-Zn also efficiently promotes the conversion of various other epoxide substrates into cyclic carbonates.Overall,the catalyst is found to have excellent substrate compatibility,stability,and recyclability.
文摘The suspension coil spring is one of the most important components in a vehicle suspension system. Its primary function is to absorb the vibrational shocks that are occasioned by irregular road surface to provide the vehicle with stability and ride comfort. The main objective of this study is to design a suspension coil spring made of structural steel for light duty vehicles with the aim of weight and cost reduction. This study was motivated by the government of Ghana’s actions to industrialise the automotive sector of the country through government policies and programs. The study made use of high carbon steel and low carbon steel as the control materials and structural steel as the implementing material. This was done to determine the suitability of structural steel for vehicle suspension coil spring. The study analysed parameters such as total deformation, equivalent Von Mises stress, maximum shear stress, and safety factor in the static structural analysis. The fatigue analysis also analysed parameters such as fatigue life and fatigue alternating stress. The results of the study revealed that the suspension spring made of structural steel has superior properties against all the parameters set for this study apart from deformation. The two control materials that are known for suspension coil spring design and manufacture have better properties to withstand deformation than the implementing material.
文摘The connecting rod is one of the most important moving components in an internal combustion engine. The present work determined the possibility of using aluminium alloy 7075 material to design and manufacture a connecting rod for weight optimisation without losing the strength of the connecting rod. It considered modal and thermal analyses to investigate the suitability of the material for connecting rod design. The parameters that were considered under the modal analysis were: total deformation, and natural frequency, while the thermal analysis looked at the temperature distribution, total heat flux and directional heat flux of the four connecting rods made with titanium alloy, grey cast iron, structural steel and aluminium 7075 alloy respectively. The connecting rod was modelled using Autodesk inventor2017 software using the calculated parameters. The steady-state thermal analysis was used to determine the induced heat flux and directional heat flux. The study found that Aluminium 7075 alloy deformed more than the remaining three other materials but has superior qualities in terms of vibrational natural frequency, total heat flux and lightweight compared to structural steel, grey cast iron and titanium alloy.
文摘Both farmers and traders benefit from trade networking, which is crucial for the local economy. Therefore, it is crucial to understand how these networks operate, and how they can be managed more effectively. Throughout this study, we examine the economic networks formed between farmers and traders through the trade of food products. These networks are analyzed from the perspective of their structure and the factors that influence their development. Using data from 18 farmers and 15 traders, we applied exponential random graph models. The results of our study showed that connectivity, Popularity Spread, activity spread, good transportation systems, and high yields all affected the development of networks. Therefore, farmers’ productivity and high market demand can contribute to local food-crop trade. The network was not affected by reciprocity, open markets, proximity to locations, or trade experience of actors. Policy makers should consider these five factors when formulating policies for local food-crop trade. Additionally, local actors should be encouraged to use these factors to improve their network development. However, it is important to note that these factors alone cannot guarantee success. Policy makers and actors must also consider other factors such as legal frameworks, economic policies, and resource availability. Our approach can be used in future research to determine how traders and farmers can enhance productivity and profit in West Africa. This study addresses a research gap by examining factors influencing local food trade in a developing country.
文摘Laser shock peening is a modernized surface enhancement performed methodically to improve fatigue life, enhance the hardness of the material and make coarse grains flat under the superficial layer. In this current study, the effect of varying optimized multiple laser shock peening (LSP) is studied on the surface integrity, microhardness, and mechanical properties. The results show that the LSP-treated specimens have visible signs of valleys, wavy and varying height distribution as well as dimples. However, the presence of non-uniformity and sharp protrusions was detected from the superficiality of the as-received specimen and this was so because of the SiC abrasive material used to polish the superficial layer of the specimen before the test experiment. Prior to LSP, the surface roughness was 2 μm, however, after LSP the roughness increased to 4 μm, 6 μm and 17 μm for 1, 2, and 4 impacts, respectively. High-density dislocation can also be observed close to the grain boundary because the grain boundary prevents the migration of dislocation which could lead to dislocation walls and dislocation tangles. The increase in impacts decrease the average grain size, nevertheless, the micro-strain increased after multiple impacts. Furthermore, coarse grains after LSP were transformed into finer grains. The increase in the number of impacts increases the micro-strain likewise the full-width half maximum (FWHM). Finally, the increase in microhardness increases as the LSP impacts increase.
文摘This study aims at developing a Knowledge Management Implementation Framework for adoption by firms in the Ghanaian construction industry. Recent developments in the field of Knowledge management in the construction sector have led to a renewed competition in driving organizational performance. However, the construction industry in Ghana lacks a knowledge management implementation framework that addresses the needs of the Ghanaian construction supply chain while a comprehensive approach to managing knowledge remains nebulous. The study adopted an extensive literature review of existing knowledge management models to provide the basis for the development of the proposed framework for Ghana. The proposed knowledge management implementation framework was subjected to testing and validation by project managers drawn from nineteen indigenous construction firms in Ghana. The technology acceptance model (TAM) was used as the criteria to validate the proposed knowledge management implementation framework. The proposed Guribie & Tengan knowledge management implementation framework was perceived to be useful, and easy to use and the intention to adopt and use was high among indigenous Ghanaian construction firms. The study recommends further validation using wider population to enhance the efficacy of the framework for wider industry acceptance to enhance organizational competitiveness and performance delivery.
文摘Understanding the weldability of steel in relation to the use of carbon equivalent is very necessary </span><span style="white-space:normal;font-family:"">for</span><span style="white-space:normal;font-family:""> the welding industry. The study was poised to unearth the fundamentals of carbon equivalent as applied in evaluating the weldability of steel. The study used </span><span style="white-space:normal;font-family:"">a </span><span style="white-space:normal;font-family:"">two-stage design approach to address the problem of carbon equivalence weldability of steel, thus, survey and experimental. Two different steels were tested to ascertain their chemical composition which could inform carbon equivalent calculation, and the results revealed microalloy and low alloy steels respectively. In subjecting the microalloy steel to carbon equivalent analyses of the AWS and IIW coefficients;revealed a value (CEV) = 0.11 each, suggesting that this microalloy steel has excellent weldability;no preheat</span><span style="white-space:normal;font-family:"">ing</span><span style="white-space:normal;font-family:""> is required. A successful welding operation on this steel does not depend on preheat</span><span style="white-space:normal;font-family:"">ing</span><span style="white-space:normal;font-family:"">.<b> </b>Also</span><span style="white-space:normal;font-family:"">,</span><span style="white-space:normal;font-family:""> the average results of the low alloy steel revealed a value (CEV) = 0.37 and 0.32 respectively, suggesting that this type of steel has very good weldability and may require </span><span style="white-space:normal;font-family:"">to </span><span style="white-space:normal;font-family:"">preheat. It is recommended that welders have </span><span style="white-space:normal;font-family:"">a </span><span style="white-space:normal;font-family:"">general idea about the weldability of steel with regard to carbon equivalent calculation. In addition</span><span style="white-space:normal;font-family:"">,</span><span style="white-space:normal;font-family:""> they should understand the chemical compositions of steels they are dealing with.
文摘Estimation methods have over the years been a problem for Statistician especially in sectors that have to do with Hidden/Hard-to-Reach population. In this paper, a regression model was derived for Elusive/Hard-to-Reach/Hidden populations. This was achieved by modelling the Multiplicity Estimator given by Birnbaum and Sirken (1965) into a regression model. The paper also gave the least-squares estimation of the unknown parameters β0 and β1, and σ2.
文摘Academia and industry research enables researchers to conduct research projects that are more relevant to current business practices and context. Although, several construction research works have been done by the academics in the tertiary institutions in Ghana, it is sad to know that, a large number of these research works have not moved from the pure stage to the applied stage. This study seeks to establish the imperative of academia and industry collaboration in building research in Ghana. A total of 116 construction practising professionals consisting of Ghana Institute of Construction (GIOC) corporate members (QS, Architects, Engineers and so on) from the industry, and academics from tertiary academic institutions (That’s, Lecturers from KNUST and UEW) that run postgraduate construction programmes in Ghana as at February 2016 constituted the respondents for this study. Census and systematic sampling techniques were used for the sampled population. Descriptive statistics was employed in the data analysis for the mean and standard deviation (SD) score values of variables. The most imperatives for academia and industry collaboration were found to be: ensuring research findings solve socio-economic and development problems, the intermittent collapse of buildings, support for the local industries to produce quality materials locally to feed the construction industry, proper contract documentations and administration. This research would bring to light the urgent issues in the construction industry that calls for greater collaboration between the academia and industry in Ghana. It reveals a deeper understanding on the need for collaborative research in the Ghanaian construction industry, by providing the most imperatives to academia-industry collaborative research in Ghana.
文摘The structural equation model (SEM) concept is generally influenced by the presence of outliers and controlling variables. To a very large extent, this could have consequential effects on the parameters and the model fitness. Though previous researches have studied outliers and controlling observations from various perspectives including the use of box plots, normal probability plots, among others, the use of uniform horizontal QQ plot is yet to be explored. This study is, therefore, aimed at applying uniform QQ plots to identifying outliers and possible controlling observations in SEM. The results showed that all the three methods of estimators manifest the ability to identify outliers and possible controlling observations in SEM. It was noted that the Anderson-Rubin estimator of QQ plot showed a more efficient or visual display of spotting outliers and possible controlling observations as compared to the other methods of estimators. Therefore, this paper provides an efficient way identifying outliers as it fragments the data set.
基金supported by the National Natural Science Foundation of China(No.51679109,51809119)the Natural Science Foundation of Jiangsu Province(BK20170555)+1 种基金the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province(17KJB470001)Special Fund for Ago-scientific Research in the Public Interest of China(201503130).
文摘Jet breakup and dispersion from impact sprinkler are mainly influenced by the configurations of nozzle and dispersion device.Based on the structure,different types of nozzles were designed and tested with a pointed tip dispersion device under low pressure conditions.Experiments were performed using High-Speed Photographic technique,and Matlab computation program was established and applied to determine the initial jet breakup length and angle of dispersion from the nozzles.The sprinkler range decreased with the increase in diameter of nozzle,and the largest range of 15.1 m was produced from sprinkler with 6 mm nozzle size under a pressure of 150 kPa.The angle of dispersion decreased with the increase of jet velocity,the spray coverage from sprinkler with 6 mm nozzle size was 1478 mm under 150 kPa,and was not statistically different when the pressure was increased.A new range formula was established for sprinkler with dispersion device through curve fitting of the parameters of initial jet breakup length,angle of dispersion,nozzle size and working pressure.The new formula was reliable for calculating range with a relative error less than 3%.Since the formula is based on the angle of dispersion,it could be useful to estimate uniformity of water distribution in sprinkler irrigated fields.
基金This work was supported by the National Natural Science Foundation of China(51679109)the Natural Science Foundation of Jiangsu Province(BK20170555)+2 种基金the Natural Foundation of the Higher Education Institutions of Jiangsu Province(17KJB470001)Special Scientific Research Fund of Agriculture Public Welfare Profession of China(201503130)Jiangsu Scientific Research and Innovation Program for Graduates in the Universities(KYLX15_1062).
文摘One way to adapt to the trend towards low-energy and to improve the hydraulic performance of the impact sprinkler under a low pressure condition is by means of a fixed water dispersion device.A fixed dispersion device disperses jet flow from the nozzle continuously.The shape of the tip,impact angle(θ),diameter(D),and depth in the jet flow(d)have significant influence on the hydraulic performance.In this study,the hydraulic performance characteristics of impact sprinkler as affected by the fixed water dispersion device were studied under indoor conditions.Radial water distributions from the sprinkler were obtained by experiments for the fixed water dispersion devices.MATLAB was used to transform the radial data into net data,and the uniformities were simulated in a square layout from 1 to 2 times the range(R).The droplet size distributions from the fixed water dispersion devices were measured by a laser precipitation monitor(LPM).Results showed that the range increased with the increase of pressure,and the sprinkler with type C_(2) produced a rectangular-shaped water distribution pattern,while the range was maintained.A maximum uniformity of 71.56%,75.56%,77.23%,73.32%,78.88%and 86.67%was found for types A1,B1,C1,A2,B2,and C_(2),respectively under a pressure of 200 kPa.The uniformity from the sprinkler using type C_(2) surpassed 80%,while type C1 fell below.Droplet sizes from type C_(2) was best,and the mean droplet diameter decreased with the increase of pressure.Hence,type C_(2) can be selected for further optimization of the design features to improve the hydraulic performance of the impact sprinkler under low pressure conditions.
基金This work was supported by the National Natural Science Foundation of China(51679109,51809119)the Natural Science Foundation of Jiangsu Province(BK20170555)+1 种基金the Natural Foundation of the Higher Education Institutions of Jiangsu Province(17KJB470001)Special Scientific Research Fund of Agriculture Public Welfare Profession of China(201503130).
文摘Water saving is an essential part of sprinkler irrigation owing to the impact of climate change and rising energy costs.This review highlights the technologies that are emerging in sprinkler irrigation to optimize crop production.While there have been notable advances in irrigation,the continued progress has occurred by the combination of current status with the postulation of new ideas such as conversion of high-pressure sprinkler to low-pressure ones,incorporation of smart controllers in sprinkler irrigation systems.To enhance the adoption of these technologies,research on the dispersion device is needed to improve the performance of impact sprinklers to efficiently operate at low-pressure conditions.It is also important to study how water savings estimates based on water use,irrigated area,longevity of saving,and level of wasteful irrigation prior to the retrofit obtained from field trials can be extrapolated to other areas with different conditions.Research in the development of optimized method for irrigation scheduling is necessary.This review emphasizes that the status of technologies should be considered a continuum,building on earlier knowledge and progress,and hopefully leading toward optimized crop production in sprinkler irrigated areas.