An optimal dimension-down iterative algorithm （DDIA） is proposed for solving a mixed （continuous/ discrete） transportation network design problem （MNDP）, which is generally expressed as a mathematical programmin...An optimal dimension-down iterative algorithm （DDIA） is proposed for solving a mixed （continuous/ discrete） transportation network design problem （MNDP）, which is generally expressed as a mathematical programming with equilibrium constraints （MPEC）. The upper level of the MNDP aims to optimize the network performance via both the expansion of existing links and the addition of new candidate links, whereas the lower level is a traditional Wardrop user equilibrium （UE） model. The idea of the proposed DDIA is to reduce the dimensions of the problem. A group of variables （discrete/continuous） are fixed to altemately optimize another group of variables （continuous/discrete）. Some continuous network design problems （CNDPs） and discrete network design problems （DNDPs） are solved repeatedly until the optimal solution is obtained. A numerical example is given to demonstrate the efficiency of the proposed algorithm.展开更多
The rapid advancement of three-dimensional printed concrete(3DPC)requires intelligent and interpretable frameworks to optimize mixture design for strength,printability,and sustainability.While machine learning(ML)mode...The rapid advancement of three-dimensional printed concrete(3DPC)requires intelligent and interpretable frameworks to optimize mixture design for strength,printability,and sustainability.While machine learning(ML)models have improved predictive accuracy,their limited transparency has hindered their widespread adoption in materials engineering.To overcome this barrier,this study introduces a Random Forests ensemble learning model integrated with SHapley Additive exPlanations(SHAP)and Partial Dependence Plots(PDPs)to model and explain the compressive strength behavior of 3DPC mixtures.Unlike conventional“black-box”models,SHAP quantifies each variable’s contribution to predictions based on cooperative game theory,which enables causal interpretability,whereas PDP visualizes nonlinear and interactive effects between features that offer practical mix design insights.A systematically optimized random forest model achieved strong generalization(R2=0.978 for training,0.834 for validation,and 0.868 for testing).The analysis identified curing age,Portland cement,silica fume,and the water-tobinder ratio as dominant predictors,with curing age exerting the highest positive influence on strength development.The integrated SHAP-PDP framework revealed synergistic interactions among binder constituents and curing parameters,which established transparent,data-driven guidelines for performance optimization.Theoretically,the study advances explainable artificial intelligence in cementitious material science by linking microstructural mechanisms to model-based reasoning,thereby enhancing both the interpretability and applicability of ML-driven mix design for next-generation 3DPC systems.展开更多
Durability design of recycled high performance concrete（RHPC） is fundamental for improving the use rate and level of concrete waste as coarse recycled aggregate（CRA）. We discussed a frostdurability-based mix propo...Durability design of recycled high performance concrete（RHPC） is fundamental for improving the use rate and level of concrete waste as coarse recycled aggregate（CRA）. We discussed a frostdurability-based mix proportion design method for RHPC using 100 % CRA and natural sand. Five groups of RHPC mixes with five strength grades（40, 50, 60, 70 and 80 MPa） were produced using CRA with four quality classes, and their workability, 28 d compressive strengths and frost resistances（measured by the compressive strength loss ratio and the relative dynamic modulus of elasticity） were tested. Relationships between the 28 d compressive strength, the frost resistance and the CRA quality characteristic parameter, water absorption, were then developed. The criterion of a CRA maximum water absorption limit value for RHPC was suggested, independent of its source and quality class. The results show that all RHPC mixes achieve the expected target workability, strength, and frost durability. The research results demonstrate that the application of the proposed method does not require trial testing prior to use.展开更多
Objective:This study provides a preliminary evaluation of the usability and acceptability of a mobile application(sexual assault care algorithm,SACA).Methods:An explanatory sequential mixed methods research was used.A...Objective:This study provides a preliminary evaluation of the usability and acceptability of a mobile application(sexual assault care algorithm,SACA).Methods:An explanatory sequential mixed methods research was used.A quantitative survey was followed up by a qualitative study.A convenience sample of participants(n=4)was recruited.The research was conducted on a one-on-one basis.In the quantitative phase,a random assignment technique was used to divide four participants into two groups of two participants each.Post-Study System Usability Questionnaire(PSSUQ)and Acceptability e-Scale were used to collect quantitative data.In the qualitative phase,interview,observation,and documentation were used to collect qualitative data.Data were analyzed both quantitative and qualitatively.The qualitative data were linked with the initial quantitative data to determine how the follow-up qualitative data helped explain the initial quantitative results.Results:The quantitative results suggested that SACA has high usability(5.05±1.83)and acceptability(3.81±1.22).The qualitative results further indicate that the participants thought SACA was easy to use and useful,and most of them would recommend it to others.Areas of improvement include adding features that would calculate and validate the elapsed time since the sexual assault,adding explanations to some buttons,and providing training.Conclusions:Our findings highlight the value of using a mixed methods research design to conduct a usability and acceptability test.Nurses are more likely to adopt a new technology for their evidencebased practice when the technology is easy to use and useful and requires less time to find the right piece of guideline evidence.Individualized training needs to be designed based on users'characteristics.展开更多
Concrete is one of the most consumable construction materials on the earth.The concrete constitutes cement,sand,gravel,water and/or additives in definite proportions.The proportions of raw materials of concrete are de...Concrete is one of the most consumable construction materials on the earth.The concrete constitutes cement,sand,gravel,water and/or additives in definite proportions.The proportions of raw materials of concrete are decided by the concrete mix design.The mix design depends on the various factors.For mix design,most of the countries have their own specifications.In the present study,standard guidelines of India,Britain and America for the concrete mix design have been discussed.The concrete grades of M25,M35 and M45 were designed and compared.Indian Standards were also compared.It was concluded that a new revised version of Indian Standard code has the lowest value of water/cement ratio and highest quantity of cement as compared to other standards.展开更多
Sulpho-aluminate expansive cementitious composite is proved to be one of the most effective ways to prevent concrete cracking too soon. Mix design of sulpho-aluminate expansive cementitious composite completely depend...Sulpho-aluminate expansive cementitious composite is proved to be one of the most effective ways to prevent concrete cracking too soon. Mix design of sulpho-aluminate expansive cementitious composite completely depends on experience and experiments at present. This method ignores the influence of expansion behavior which hinders the application of sulpho-aluminate expansive cementitious composite. The workability,free expansion property,flexural strength and compressive strength of sulpho-aluminate expansive cementitious composite have been investigated by tests. The relationship between expansion ratio and mix design parameters such as curing age,water-cement ratio and cement abundance coefficient is deduced according to the experimental statistics. A new simplified approach to mix design of sulpho-aluminate expansive cementitious composite is proposed as a reference for construction application,which avoids experiments and experience.展开更多
Research on mixed method has made great development.In order to explore the practical application of mixed method,this article starts from the perspective of language learner cognition and selects The Modern Language ...Research on mixed method has made great development.In order to explore the practical application of mixed method,this article starts from the perspective of language learner cognition and selects The Modern Language Journal and Language Teaching Research as the research journals.It explores some empirical papers that used mixed method to learn the specific research designs of mixed method as well as the main means of its application.The study finds that mixed method has been applied in several fields and is more scientifically reliable than qualitative and quantitative methods especially in language learner cognition,and the different research tools used in the field of language learner cognition demonstrate the flexibility and relevance of mixed method data collection.展开更多
Current mix design practices typically assume total blending and use the white curve of reclaimed asphalt pavement(RAP)to determine the gradation and optimum asphalt content(OAC)of recycled hot mix asphalt(HMA),often ...Current mix design practices typically assume total blending and use the white curve of reclaimed asphalt pavement(RAP)to determine the gradation and optimum asphalt content(OAC)of recycled hot mix asphalt(HMA),often overlooking the effects of RAP agglomeration and partial blending.This oversight can result in unsatisfactory performance,particularly when higher RAP content is used.Therefore,this paper reviews and discusses strategies for adjusting the mix design of recycled HMA to enhance its in-service performance.The discussion begins with RAP particle agglomeration,a significant phenomenon that significantly impacts the aggregate gradation of recycled HMA.Subsequently,detection methods to clarify the blending between virgin and RAP binders are described.Partial blending between RAP and virgin binders is common,and various indexes have been proposed to quantify the blending degree.Finally,the adjusted mix design method of recycled HMA is presented,emphasizing gradation optimization and corrected OAC.Gradation optimization should account for RAP agglomeration,while the corrected OAC should consider particle blending.Recycled HMA using the adjusted mix design exhibits improved crack resistance and fatigue life without substantially impairing rutting performance.This review aims to help both academics and highway agencies maximize the utilization of RAP materials within sustainable pavement frameworks.展开更多
The mix designs and specimen preparation for the dry process and wet process of sulfur rubber conerete （ SRC ） were investigated. The compressive strength, corrosion-resistance and toughness were studied and discuss...The mix designs and specimen preparation for the dry process and wet process of sulfur rubber conerete （ SRC ） were investigated. The compressive strength, corrosion-resistance and toughness were studied and discussed. The results show that SRC is corrosion-resistanet. Although the compressive strength of SRC decreases with inereasing rubber content, the toughness increases instead . Adding micro-filler will improve the compressive strength of SRC . There is a threshold value for the sulfur content, at which the compressive strength and the workability of SRC reach an optimum balance . The bond between rubber particles and surrounding sulfur is strong due to the vulcanization process that generates cross-link through S-C bonds.展开更多
A novel soft initiai-rotation control system and an H∞ robust constant rotational speed controller （RCRSC） for a rotational MEMS （micro-electro-mechanical system） gyro are presented. The soft initial-rotation con...A novel soft initiai-rotation control system and an H∞ robust constant rotational speed controller （RCRSC） for a rotational MEMS （micro-electro-mechanical system） gyro are presented. The soft initial-rotation control system can prevent the possible tumbling down of the suspended rotor and ensure a smooth and fast initial-rotation process. After the initial-rotation process, in order to maintain the rotational speed accurately constant, the RCRSC is acquired through the mixed sensitivity design approach. Simulation results show that the actuation voltage disturbances from the internal carrier waves in the gyro is reduced by more than 15.3 dB, and the speed fluctuations due to typical external vibrations ranging from 10 Hz to 200 Hz can also be restricted to 10^-3 rad/s order.展开更多
There is a scarcity of literature discussing nurses’ behaviors toward caring for suspected or confirmed human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients. The development of a scal...There is a scarcity of literature discussing nurses’ behaviors toward caring for suspected or confirmed human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients. The development of a scale specific to measure nurses’ behaviors will allow health institutions to assess the disposition of their nurses in terms of HIV care. This study aims to present the rigors of developing and validating a reliable instrument to contextualize these nurses’ behaviors. This study utilized a sequential exploratory mixed method design to develop the NB-CSHAP scale. Thematic analysis was done on the qualitative data from the interviews with persons living with HIV/AIDS (PLHA) from which items were selected to be included in the scale. Exploratory factor analysis was utilized to extract the factors and Cronbach’s alpha was used to assess the reliability of the instrument. Four factors were extracted and are categorized as either caring or discriminatory behaviors. These include: (1) service-oriented, (2) openhanded, (3) perceptive, and (4) discriminatory. The scale has an internal consistency of 0.73. The scale shows acceptable psychometric properties, hence can be used to assess the nurses’ behaviors in caring for confirmed or suspected HIV clients. The scale may be used by health institutions to determine the quality of the patient care provided by their nurses to clients with confirmed or suspected HIV .展开更多
The early asphalt pavement in our country severely reduced the road performance due to various external factors during the use process.According to incomplete statistics,there are more asphalt pavements that need to b...The early asphalt pavement in our country severely reduced the road performance due to various external factors during the use process.According to incomplete statistics,there are more asphalt pavements that need to be renovated and repaired every year in China,and the amount of construction waste such as asphalt concrete and other construction waste reaches 1,000.About ten thousand tons.If such a huge amount of construction waste is not used,it will inevitably cause great pollution to the environment.If it can be reused,not only will it be environmentally friendly and energy-saving,it will also save more than one billion yuan in costs.In view of the above problems,this article conducts related Research and Analysis on the Principle in Plant Cold Recycling for Foamed Bitumen and Mixture Performance to provide reference for future projects.展开更多
Copper metallurgical slags are solid wastes resulting from the copper extraction process through pyrometallurgy. These granulated materials, dumped in the center of the city of Lubumbashi, contain certain “trace meta...Copper metallurgical slags are solid wastes resulting from the copper extraction process through pyrometallurgy. These granulated materials, dumped in the center of the city of Lubumbashi, contain certain “trace metal elements (ETM)” and/or “heavy metals” and are subjected to aerial leaching during the dry season, causing air pollution, and to leaching by rainwater, which leads to the contamination of the surrounding soil and surface water. The objective of this work was to use these slags, poor in recoverable elements (Cu, Co, Zn, Ge, and Ga), as fine aggregates for partial replacement of sand in concrete. The slags studied are of the ferrosilicate type belonging to the SiO2-FeO-CaO (MgO-Al2O3) system. They are completely vitreous, and their grain size distribution ranges from 0 to 3 mm. For this study, crushed sand with a granulometric distribution similar to that of the slags was chosen. The Bolomey method was used to optimize the sand content of the concrete as well as to calculate the optimum amount of water for concrete production. Once optimized, the sand was replaced with slag at respective rates of 0%, 25%, 50%, 75%, and 100% by weight. The compressive strengths of the hardened concretes based on these slags were measured at 1, 3, 7, 14, and 28 days of curing with a W/C (Water/Cement) ratio of 0.6. Slump tests of the fresh concrete were conducted to characterize the influence of sand replacement by slag on the concrete’s workability. The durability of the concrete with the optimized slag content was studied in corrosive solutions of HCl (5% wt), H2SO4 (3% wt), and Na2SO4 (1% wt). The results show the possibility of replacing crushed sand with slag up to a maximum rate of 50% by weight. The use of copper slag as sand decreases the cement’s water demand and therefore increases the value of the concrete’s mechanical strength. It was found that the optimum W/C ratio that allows for acceptable workability of the slag-based concrete is around 0.49. The durability study of the slag-based concretes in various corrosive solutions showed better performance of the slag-based concrete in the presence of H2SO4 and Na2SO4 solutions. Using the slag as a fine aggregate densifies the concrete structure, improves its workability by decreasing its W/C ratio, and increases its mechanical strengths while improving its resistance to corrosive environments.展开更多
ARHM asphalt rubber has been applied in pavement engineering research for more than 20 years in our country. It has been applied and popularized in Beijing-Qinhuangdao Expressway, Jinshi Expressway and other projects ...ARHM asphalt rubber has been applied in pavement engineering research for more than 20 years in our country. It has been applied and popularized in Beijing-Qinhuangdao Expressway, Jinshi Expressway and other projects successively, but its content is relatively low. According to the characteristics that rubber powder can greatly improve the durability of asphalt concrete, the research on the mix proportion of high content (30%) rubber powder asphalt concrete was carried out. It has been verified that it has significantly improved the dynamic stability, low-temperature bending, freeze-thaw splitting and water seepage performance, and has been put into use in the bid section ZT2 of Jingde Expressway, meeting the use requirements of "no minor repair for 15 years and no major repair for 40 years" for the permanent pavement of Jingde Expressway.展开更多
With the resource shortage in coastal areas,the construction of concrete structures using freshwater and river sand has brought great economic and environmental costs.The use of seawater,sea sand,and coral aggregates ...With the resource shortage in coastal areas,the construction of concrete structures using freshwater and river sand has brought great economic and environmental costs.The use of seawater,sea sand,and coral aggregates in concrete mixes has become an alternative solution for coastal and marine structures,especially for offshore structures and artificial islands.In this study,378 seawater,sea sand,and coral aggregate concrete(Coral-SWSSC)specimens were prepared,and their mechanical properties were investigated comprehensively through compressive tests to explore the optimized mix design at different grades.Results showed that the mechanical properties of Coral-SWSSC were strongly correlated with the water-to-binder ratios,coastal particle gradings,and pretreatment method of coastal particles.Based on the experimental results,mix proportion designs of CoralSWSSC were proposed for concrete from C20 to C50 grades,and the failure mechanism of Coral-SWSSC at different grades was discussed according to their respective failure modes.The findings of the current study provide knowledge on the optimized design of Coral-SWSSC,which can be used to promote the application of Coral-SWSSC in offshore,marine,and ocean engineering.展开更多
This research explored the application potential of PUM thin-overlay technology on airport rapid maintenance.The rapid curing process of polyurethane binder determines the limited time window for mixing and constructi...This research explored the application potential of PUM thin-overlay technology on airport rapid maintenance.The rapid curing process of polyurethane binder determines the limited time window for mixing and construction of polyurethane-bonded mixture(PUM),which presents significant difference with hot-mix asphalt(HMA)technology.Therefore,this research investigated and optimized the mix design of PUM for airport thin-overlay technology based on its thermosetting characteristics.First,limestone and basalt were comprehensively compared as an aggregate for PUM.Then,the effects of molding and curing conditions were studied in terms of mixing time,molding method,molding parameters and curing temperature.Statistical analysis was also conducted to evaluate the effects of gradation and particle size on PUM performances based on gray relational analysis(GRA),thus determining the key particle size to control PUM performances.Finally,the internal structural details of PUM were captured by X-ray CT scan test.The results demonstrated that it only took 12 hours to reach 75%of maximum strength at a curing temperature of 50°C,indicating an efficient curing process and in turn allowing short traffic delay.The internal structural details of PUM presented distribution of tiny pores with few connective voids,guaranteeing waterproof property and high strength.展开更多
The present study proposes the mix design method of Fly Ash(FA)based geopolymer concrete using Response Surface Methodology(RSM).In this method,different factors,including binder content,alkali/binder ratio,NS/NH rati...The present study proposes the mix design method of Fly Ash(FA)based geopolymer concrete using Response Surface Methodology(RSM).In this method,different factors,including binder content,alkali/binder ratio,NS/NH ratio(sodium silicate/sodium hydroxide),NH molarity,and water/solids ratio were considered for the mix design of geopolymer concrete.The 2D contour plots were used to setup the mix design method to achieve the target compressive strength.The proposed mix design method of geopolymer concrete is divided into three categories based on curing regime,specifically one ambient curing(25°C)and two heat curing(60 and 90°C).The proposed mix design method of geopolymer concrete was validated through experimentation of M30,M50,and M70 concrete mixes at all curing regimes.The observed experimental compressive strength results validate the mix design method by more than 90%of their target strength.Furthermore,the current study concluded that the required compressive strength can be achieved by varying any factor in the mix design.In addition,the factor analysis revealed that the NS/NH ratio significantly affects the compressive strength of geopolymer concrete.展开更多
Pavement and mix design represent one of the key components within the life cycle of a road infrastructure, with links to political, economic, technical, societal and environmental issues. Recent researches related to...Pavement and mix design represent one of the key components within the life cycle of a road infrastructure, with links to political, economic, technical, societal and environmental issues. Recent researches related to the characteristics of materials and associated behavior models both for materials and pavement, made it appropriate to consider updating current pavement design methods, and especially in the USA this has already been in process while in Europe uses of the methods developed in the early 1970s. Thus, this paper firstly presents a brief historical overview of pavement design methods, high- lighting early limitations of old empirical methods. Afterwards, French, UK and Shell methods currently in use in Europe will be presented, undeHining their main components in terms of methodology, traffic, climatic conditions and subgrade. The asphalt mix design and modeling in Europe are presented with their inclusion in the pavement design methods. Finally, the main challenges for the development of a European pavement design method are presented as well as the recent research developments that can be used for that method.展开更多
The clay mineral composition is one of the major factors that governs the physical properties of silty sand subgrade. Therefore, a thorough knowledge of mineral composition is essential to predict the optimum engineer...The clay mineral composition is one of the major factors that governs the physical properties of silty sand subgrade. Therefore, a thorough knowledge of mineral composition is essential to predict the optimum engineering properties of the soil, which is generally characterized by different indices like maximum dry density （MDD）, California bearing ratio （CBR）, unconfined compressive strength （UCS） and free swelling index （FSI）. In this article, a novel multi- attribute decision making （MADM） based approach of mix design has been proposed for silty sand- artificial clay mix to improve the characteristic strength of a soil subgrade. Experimental investigation has been carried out in this study to illustrate the proposed approach of selecting appropriate proportion for the soil mix to optimize all the above mentioned engineering properties simultaneously. The results show that a mix proportion containing approximately 90% silty sand plus 10% bentonite soil is the optimal combination in context to the present study. The proposed methodology for optimal decision making to choose appropriate combination of bentonite and silty sand is general in nature and therefore, it can be extended to other problems of selecting mineral compositions.展开更多
基金The National Natural Science Foundation of China(No. 50908235 )China Postdoctoral Science Foundation (No.201003520)
文摘An optimal dimension-down iterative algorithm （DDIA） is proposed for solving a mixed （continuous/ discrete） transportation network design problem （MNDP）, which is generally expressed as a mathematical programming with equilibrium constraints （MPEC）. The upper level of the MNDP aims to optimize the network performance via both the expansion of existing links and the addition of new candidate links, whereas the lower level is a traditional Wardrop user equilibrium （UE） model. The idea of the proposed DDIA is to reduce the dimensions of the problem. A group of variables （discrete/continuous） are fixed to altemately optimize another group of variables （continuous/discrete）. Some continuous network design problems （CNDPs） and discrete network design problems （DNDPs） are solved repeatedly until the optimal solution is obtained. A numerical example is given to demonstrate the efficiency of the proposed algorithm.
基金supported by the Ongoing Research Funding Program(Grant No.ORFFT-2025-025-4)at King Saud University,Riyadh,Saudi Arabia.The grant was awarded to Yassir M.Abbas。
文摘The rapid advancement of three-dimensional printed concrete(3DPC)requires intelligent and interpretable frameworks to optimize mixture design for strength,printability,and sustainability.While machine learning(ML)models have improved predictive accuracy,their limited transparency has hindered their widespread adoption in materials engineering.To overcome this barrier,this study introduces a Random Forests ensemble learning model integrated with SHapley Additive exPlanations(SHAP)and Partial Dependence Plots(PDPs)to model and explain the compressive strength behavior of 3DPC mixtures.Unlike conventional“black-box”models,SHAP quantifies each variable’s contribution to predictions based on cooperative game theory,which enables causal interpretability,whereas PDP visualizes nonlinear and interactive effects between features that offer practical mix design insights.A systematically optimized random forest model achieved strong generalization(R2=0.978 for training,0.834 for validation,and 0.868 for testing).The analysis identified curing age,Portland cement,silica fume,and the water-tobinder ratio as dominant predictors,with curing age exerting the highest positive influence on strength development.The integrated SHAP-PDP framework revealed synergistic interactions among binder constituents and curing parameters,which established transparent,data-driven guidelines for performance optimization.Theoretically,the study advances explainable artificial intelligence in cementitious material science by linking microstructural mechanisms to model-based reasoning,thereby enhancing both the interpretability and applicability of ML-driven mix design for next-generation 3DPC systems.
基金Funded by the National Natural Science Foundation of China(No.51278073)Prospective Joint Research Project of Jiangsu Province(No.BY2015027-23)State Key Laboratory for Geo Mechanics and Deep Underground Engineering,China University of Mining&Technology(No.SKLGDUEK1704)
文摘Durability design of recycled high performance concrete（RHPC） is fundamental for improving the use rate and level of concrete waste as coarse recycled aggregate（CRA）. We discussed a frostdurability-based mix proportion design method for RHPC using 100 % CRA and natural sand. Five groups of RHPC mixes with five strength grades（40, 50, 60, 70 and 80 MPa） were produced using CRA with four quality classes, and their workability, 28 d compressive strengths and frost resistances（measured by the compressive strength loss ratio and the relative dynamic modulus of elasticity） were tested. Relationships between the 28 d compressive strength, the frost resistance and the CRA quality characteristic parameter, water absorption, were then developed. The criterion of a CRA maximum water absorption limit value for RHPC was suggested, independent of its source and quality class. The results show that all RHPC mixes achieve the expected target workability, strength, and frost durability. The research results demonstrate that the application of the proposed method does not require trial testing prior to use.
基金The development of the application for SACA was partially supported by funding from the Upstate Foundation,a 501(c)3 nonfor-profit corporation (upstatefoundation.org)
文摘Objective:This study provides a preliminary evaluation of the usability and acceptability of a mobile application(sexual assault care algorithm,SACA).Methods:An explanatory sequential mixed methods research was used.A quantitative survey was followed up by a qualitative study.A convenience sample of participants(n=4)was recruited.The research was conducted on a one-on-one basis.In the quantitative phase,a random assignment technique was used to divide four participants into two groups of two participants each.Post-Study System Usability Questionnaire(PSSUQ)and Acceptability e-Scale were used to collect quantitative data.In the qualitative phase,interview,observation,and documentation were used to collect qualitative data.Data were analyzed both quantitative and qualitatively.The qualitative data were linked with the initial quantitative data to determine how the follow-up qualitative data helped explain the initial quantitative results.Results:The quantitative results suggested that SACA has high usability(5.05±1.83)and acceptability(3.81±1.22).The qualitative results further indicate that the participants thought SACA was easy to use and useful,and most of them would recommend it to others.Areas of improvement include adding features that would calculate and validate the elapsed time since the sexual assault,adding explanations to some buttons,and providing training.Conclusions:Our findings highlight the value of using a mixed methods research design to conduct a usability and acceptability test.Nurses are more likely to adopt a new technology for their evidencebased practice when the technology is easy to use and useful and requires less time to find the right piece of guideline evidence.Individualized training needs to be designed based on users'characteristics.
文摘Concrete is one of the most consumable construction materials on the earth.The concrete constitutes cement,sand,gravel,water and/or additives in definite proportions.The proportions of raw materials of concrete are decided by the concrete mix design.The mix design depends on the various factors.For mix design,most of the countries have their own specifications.In the present study,standard guidelines of India,Britain and America for the concrete mix design have been discussed.The concrete grades of M25,M35 and M45 were designed and compared.Indian Standards were also compared.It was concluded that a new revised version of Indian Standard code has the lowest value of water/cement ratio and highest quantity of cement as compared to other standards.
基金Supported by Projects of NSFC(No.51108207)Science and Technology Development Planning of Jilin Province(No.201201057)
文摘Sulpho-aluminate expansive cementitious composite is proved to be one of the most effective ways to prevent concrete cracking too soon. Mix design of sulpho-aluminate expansive cementitious composite completely depends on experience and experiments at present. This method ignores the influence of expansion behavior which hinders the application of sulpho-aluminate expansive cementitious composite. The workability,free expansion property,flexural strength and compressive strength of sulpho-aluminate expansive cementitious composite have been investigated by tests. The relationship between expansion ratio and mix design parameters such as curing age,water-cement ratio and cement abundance coefficient is deduced according to the experimental statistics. A new simplified approach to mix design of sulpho-aluminate expansive cementitious composite is proposed as a reference for construction application,which avoids experiments and experience.
文摘Research on mixed method has made great development.In order to explore the practical application of mixed method,this article starts from the perspective of language learner cognition and selects The Modern Language Journal and Language Teaching Research as the research journals.It explores some empirical papers that used mixed method to learn the specific research designs of mixed method as well as the main means of its application.The study finds that mixed method has been applied in several fields and is more scientifically reliable than qualitative and quantitative methods especially in language learner cognition,and the different research tools used in the field of language learner cognition demonstrate the flexibility and relevance of mixed method data collection.
基金sponsored by the National Natural Science Foundation of China(52178420,52408476)Special subsidy from Heilongjiang Provincial People's Government(HITTY-20190028)+1 种基金Postdoctoral Fellowship Program of CPSF(GZC20242207)the Fundamental Research Funds for the Central Universities(HIT.DZJJ.2023086).
文摘Current mix design practices typically assume total blending and use the white curve of reclaimed asphalt pavement(RAP)to determine the gradation and optimum asphalt content(OAC)of recycled hot mix asphalt(HMA),often overlooking the effects of RAP agglomeration and partial blending.This oversight can result in unsatisfactory performance,particularly when higher RAP content is used.Therefore,this paper reviews and discusses strategies for adjusting the mix design of recycled HMA to enhance its in-service performance.The discussion begins with RAP particle agglomeration,a significant phenomenon that significantly impacts the aggregate gradation of recycled HMA.Subsequently,detection methods to clarify the blending between virgin and RAP binders are described.Partial blending between RAP and virgin binders is common,and various indexes have been proposed to quantify the blending degree.Finally,the adjusted mix design method of recycled HMA is presented,emphasizing gradation optimization and corrected OAC.Gradation optimization should account for RAP agglomeration,while the corrected OAC should consider particle blending.Recycled HMA using the adjusted mix design exhibits improved crack resistance and fatigue life without substantially impairing rutting performance.This review aims to help both academics and highway agencies maximize the utilization of RAP materials within sustainable pavement frameworks.
基金Funded by the Natural Science Foundation of China ( No.50408004)
文摘The mix designs and specimen preparation for the dry process and wet process of sulfur rubber conerete （ SRC ） were investigated. The compressive strength, corrosion-resistance and toughness were studied and discussed. The results show that SRC is corrosion-resistanet. Although the compressive strength of SRC decreases with inereasing rubber content, the toughness increases instead . Adding micro-filler will improve the compressive strength of SRC . There is a threshold value for the sulfur content, at which the compressive strength and the workability of SRC reach an optimum balance . The bond between rubber particles and surrounding sulfur is strong due to the vulcanization process that generates cross-link through S-C bonds.
基金supported by the National High Technology Research and Development Program of China(863 Program)(2002AA745120)the National Defense Pre-research Foundation(9140A09020706JW314)the National Natural Science Foundationof China(160402003).
文摘A novel soft initiai-rotation control system and an H∞ robust constant rotational speed controller （RCRSC） for a rotational MEMS （micro-electro-mechanical system） gyro are presented. The soft initial-rotation control system can prevent the possible tumbling down of the suspended rotor and ensure a smooth and fast initial-rotation process. After the initial-rotation process, in order to maintain the rotational speed accurately constant, the RCRSC is acquired through the mixed sensitivity design approach. Simulation results show that the actuation voltage disturbances from the internal carrier waves in the gyro is reduced by more than 15.3 dB, and the speed fluctuations due to typical external vibrations ranging from 10 Hz to 200 Hz can also be restricted to 10^-3 rad/s order.
文摘There is a scarcity of literature discussing nurses’ behaviors toward caring for suspected or confirmed human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients. The development of a scale specific to measure nurses’ behaviors will allow health institutions to assess the disposition of their nurses in terms of HIV care. This study aims to present the rigors of developing and validating a reliable instrument to contextualize these nurses’ behaviors. This study utilized a sequential exploratory mixed method design to develop the NB-CSHAP scale. Thematic analysis was done on the qualitative data from the interviews with persons living with HIV/AIDS (PLHA) from which items were selected to be included in the scale. Exploratory factor analysis was utilized to extract the factors and Cronbach’s alpha was used to assess the reliability of the instrument. Four factors were extracted and are categorized as either caring or discriminatory behaviors. These include: (1) service-oriented, (2) openhanded, (3) perceptive, and (4) discriminatory. The scale has an internal consistency of 0.73. The scale shows acceptable psychometric properties, hence can be used to assess the nurses’ behaviors in caring for confirmed or suspected HIV clients. The scale may be used by health institutions to determine the quality of the patient care provided by their nurses to clients with confirmed or suspected HIV .
基金the research result of the project"Research and Analysis of the Recycling and Utilization of Waste Concrete Based on Energy-saving and Environmental Protection"PJ20201390519 of the project of"Innovation and Entrepreneurship Training Program for College Students in 2020".Instructor:Congrong Tang。
文摘The early asphalt pavement in our country severely reduced the road performance due to various external factors during the use process.According to incomplete statistics,there are more asphalt pavements that need to be renovated and repaired every year in China,and the amount of construction waste such as asphalt concrete and other construction waste reaches 1,000.About ten thousand tons.If such a huge amount of construction waste is not used,it will inevitably cause great pollution to the environment.If it can be reused,not only will it be environmentally friendly and energy-saving,it will also save more than one billion yuan in costs.In view of the above problems,this article conducts related Research and Analysis on the Principle in Plant Cold Recycling for Foamed Bitumen and Mixture Performance to provide reference for future projects.
文摘Copper metallurgical slags are solid wastes resulting from the copper extraction process through pyrometallurgy. These granulated materials, dumped in the center of the city of Lubumbashi, contain certain “trace metal elements (ETM)” and/or “heavy metals” and are subjected to aerial leaching during the dry season, causing air pollution, and to leaching by rainwater, which leads to the contamination of the surrounding soil and surface water. The objective of this work was to use these slags, poor in recoverable elements (Cu, Co, Zn, Ge, and Ga), as fine aggregates for partial replacement of sand in concrete. The slags studied are of the ferrosilicate type belonging to the SiO2-FeO-CaO (MgO-Al2O3) system. They are completely vitreous, and their grain size distribution ranges from 0 to 3 mm. For this study, crushed sand with a granulometric distribution similar to that of the slags was chosen. The Bolomey method was used to optimize the sand content of the concrete as well as to calculate the optimum amount of water for concrete production. Once optimized, the sand was replaced with slag at respective rates of 0%, 25%, 50%, 75%, and 100% by weight. The compressive strengths of the hardened concretes based on these slags were measured at 1, 3, 7, 14, and 28 days of curing with a W/C (Water/Cement) ratio of 0.6. Slump tests of the fresh concrete were conducted to characterize the influence of sand replacement by slag on the concrete’s workability. The durability of the concrete with the optimized slag content was studied in corrosive solutions of HCl (5% wt), H2SO4 (3% wt), and Na2SO4 (1% wt). The results show the possibility of replacing crushed sand with slag up to a maximum rate of 50% by weight. The use of copper slag as sand decreases the cement’s water demand and therefore increases the value of the concrete’s mechanical strength. It was found that the optimum W/C ratio that allows for acceptable workability of the slag-based concrete is around 0.49. The durability study of the slag-based concretes in various corrosive solutions showed better performance of the slag-based concrete in the presence of H2SO4 and Na2SO4 solutions. Using the slag as a fine aggregate densifies the concrete structure, improves its workability by decreasing its W/C ratio, and increases its mechanical strengths while improving its resistance to corrosive environments.
文摘ARHM asphalt rubber has been applied in pavement engineering research for more than 20 years in our country. It has been applied and popularized in Beijing-Qinhuangdao Expressway, Jinshi Expressway and other projects successively, but its content is relatively low. According to the characteristics that rubber powder can greatly improve the durability of asphalt concrete, the research on the mix proportion of high content (30%) rubber powder asphalt concrete was carried out. It has been verified that it has significantly improved the dynamic stability, low-temperature bending, freeze-thaw splitting and water seepage performance, and has been put into use in the bid section ZT2 of Jingde Expressway, meeting the use requirements of "no minor repair for 15 years and no major repair for 40 years" for the permanent pavement of Jingde Expressway.
基金supported by the National Natural Science Foundation of China (Grant Nos.52078310,51878420)the Ministry of Science and Technology of China (Grant Nos.2018YFC1504303,2017YFC1503103)Xingliao Talent Program of Liaoning Province (Grant No.XLYC1902038)。
文摘With the resource shortage in coastal areas,the construction of concrete structures using freshwater and river sand has brought great economic and environmental costs.The use of seawater,sea sand,and coral aggregates in concrete mixes has become an alternative solution for coastal and marine structures,especially for offshore structures and artificial islands.In this study,378 seawater,sea sand,and coral aggregate concrete(Coral-SWSSC)specimens were prepared,and their mechanical properties were investigated comprehensively through compressive tests to explore the optimized mix design at different grades.Results showed that the mechanical properties of Coral-SWSSC were strongly correlated with the water-to-binder ratios,coastal particle gradings,and pretreatment method of coastal particles.Based on the experimental results,mix proportion designs of CoralSWSSC were proposed for concrete from C20 to C50 grades,and the failure mechanism of Coral-SWSSC at different grades was discussed according to their respective failure modes.The findings of the current study provide knowledge on the optimized design of Coral-SWSSC,which can be used to promote the application of Coral-SWSSC in offshore,marine,and ocean engineering.
基金This study was supported by the National Natural Science Foundation of China under Grant number of 51861145402.
文摘This research explored the application potential of PUM thin-overlay technology on airport rapid maintenance.The rapid curing process of polyurethane binder determines the limited time window for mixing and construction of polyurethane-bonded mixture(PUM),which presents significant difference with hot-mix asphalt(HMA)technology.Therefore,this research investigated and optimized the mix design of PUM for airport thin-overlay technology based on its thermosetting characteristics.First,limestone and basalt were comprehensively compared as an aggregate for PUM.Then,the effects of molding and curing conditions were studied in terms of mixing time,molding method,molding parameters and curing temperature.Statistical analysis was also conducted to evaluate the effects of gradation and particle size on PUM performances based on gray relational analysis(GRA),thus determining the key particle size to control PUM performances.Finally,the internal structural details of PUM were captured by X-ray CT scan test.The results demonstrated that it only took 12 hours to reach 75%of maximum strength at a curing temperature of 50°C,indicating an efficient curing process and in turn allowing short traffic delay.The internal structural details of PUM presented distribution of tiny pores with few connective voids,guaranteeing waterproof property and high strength.
文摘The present study proposes the mix design method of Fly Ash(FA)based geopolymer concrete using Response Surface Methodology(RSM).In this method,different factors,including binder content,alkali/binder ratio,NS/NH ratio(sodium silicate/sodium hydroxide),NH molarity,and water/solids ratio were considered for the mix design of geopolymer concrete.The 2D contour plots were used to setup the mix design method to achieve the target compressive strength.The proposed mix design method of geopolymer concrete is divided into three categories based on curing regime,specifically one ambient curing(25°C)and two heat curing(60 and 90°C).The proposed mix design method of geopolymer concrete was validated through experimentation of M30,M50,and M70 concrete mixes at all curing regimes.The observed experimental compressive strength results validate the mix design method by more than 90%of their target strength.Furthermore,the current study concluded that the required compressive strength can be achieved by varying any factor in the mix design.In addition,the factor analysis revealed that the NS/NH ratio significantly affects the compressive strength of geopolymer concrete.
基金the support of Portuguese National Funding Agency for Science, Research and Technology (FCT) through scholarship SFRH/BSAB/114415/ 2016
文摘Pavement and mix design represent one of the key components within the life cycle of a road infrastructure, with links to political, economic, technical, societal and environmental issues. Recent researches related to the characteristics of materials and associated behavior models both for materials and pavement, made it appropriate to consider updating current pavement design methods, and especially in the USA this has already been in process while in Europe uses of the methods developed in the early 1970s. Thus, this paper firstly presents a brief historical overview of pavement design methods, high- lighting early limitations of old empirical methods. Afterwards, French, UK and Shell methods currently in use in Europe will be presented, undeHining their main components in terms of methodology, traffic, climatic conditions and subgrade. The asphalt mix design and modeling in Europe are presented with their inclusion in the pavement design methods. Finally, the main challenges for the development of a European pavement design method are presented as well as the recent research developments that can be used for that method.
文摘The clay mineral composition is one of the major factors that governs the physical properties of silty sand subgrade. Therefore, a thorough knowledge of mineral composition is essential to predict the optimum engineering properties of the soil, which is generally characterized by different indices like maximum dry density （MDD）, California bearing ratio （CBR）, unconfined compressive strength （UCS） and free swelling index （FSI）. In this article, a novel multi- attribute decision making （MADM） based approach of mix design has been proposed for silty sand- artificial clay mix to improve the characteristic strength of a soil subgrade. Experimental investigation has been carried out in this study to illustrate the proposed approach of selecting appropriate proportion for the soil mix to optimize all the above mentioned engineering properties simultaneously. The results show that a mix proportion containing approximately 90% silty sand plus 10% bentonite soil is the optimal combination in context to the present study. The proposed methodology for optimal decision making to choose appropriate combination of bentonite and silty sand is general in nature and therefore, it can be extended to other problems of selecting mineral compositions.
