The cracking behavior of lightweight aggregate concrete(LWAC) was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship betw...The cracking behavior of lightweight aggregate concrete(LWAC) was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship between the ceramsite type and the cracking resistance of LWAC was built up and compared with that of normal-weight coarse aggregate concrete(NWAC). A new method was proposed to evaluate the cracking resistance of concrete, where the concepts of cracking coefficient ζt(t) and the evaluation index Acr(t) were proposed, and the development of micro-cracks and damage accumulation were recognized. For the concrete with an ascending cracking coefficient curve, the larger Acr(t) is, the lower cracking resistance of concrete is. For the concrete with a descending cracking coefficient curve, the larger Acr(t) is, the stronger the cracking resistance of concrete is. The evaluation results show that in the case of that all the three types of coarse aggregates in concrete are pre-soaked for 24 h, NWAC has the lowest cracking resistance, followed by the LWAC with lower water absorption capacity ceramsite and the LWAC with higher water absorption capacity ceramsite has the strongest cracking resistance. The proposed method has obvious advantages over the cracking age method, because it can evaluate the cracking behavior of concrete even if the concrete has not an observable crack.展开更多
With the continuous development of science and technology and other fields in today's world,statistical analysis and research have become indispensable research methods in people's daily lives.Among these,hypo...With the continuous development of science and technology and other fields in today's world,statistical analysis and research have become indispensable research methods in people's daily lives.Among these,hypothesis testing plays an important role in fields such as biology,medicine,and economics,and has significant effects in most scenarios.However,the suitability and effectiveness of different hypothesis testing methods vary depending on the context,often leading to different outcomes and levels of accuracy.This paper focuses on discussing various hypothesis testing methods in statistics,such as t-test,chi-square test,z-test,F-test,etc.In addition,this study analyzes various cases in real life and optimize and improve some hypothesis testing methods.Based on a review of existing literature,the study explores how traditional hypothesis testing determines statistical significance—where the null hypothesis is rejected if the test statistic falls within the rejection region.To improve and enhance the determination of the significance level,handle uncertainty,and increase the sample size,this paper proposes alternative methods such as NHST test,Bayesian test,big data sequential test,and failure rate hypothesis test from the perspectives of medicine and kinesiology.展开更多
基金Project(51078090)supported by the National Natural Science Foundation of China
文摘The cracking behavior of lightweight aggregate concrete(LWAC) was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship between the ceramsite type and the cracking resistance of LWAC was built up and compared with that of normal-weight coarse aggregate concrete(NWAC). A new method was proposed to evaluate the cracking resistance of concrete, where the concepts of cracking coefficient ζt(t) and the evaluation index Acr(t) were proposed, and the development of micro-cracks and damage accumulation were recognized. For the concrete with an ascending cracking coefficient curve, the larger Acr(t) is, the lower cracking resistance of concrete is. For the concrete with a descending cracking coefficient curve, the larger Acr(t) is, the stronger the cracking resistance of concrete is. The evaluation results show that in the case of that all the three types of coarse aggregates in concrete are pre-soaked for 24 h, NWAC has the lowest cracking resistance, followed by the LWAC with lower water absorption capacity ceramsite and the LWAC with higher water absorption capacity ceramsite has the strongest cracking resistance. The proposed method has obvious advantages over the cracking age method, because it can evaluate the cracking behavior of concrete even if the concrete has not an observable crack.
文摘With the continuous development of science and technology and other fields in today's world,statistical analysis and research have become indispensable research methods in people's daily lives.Among these,hypothesis testing plays an important role in fields such as biology,medicine,and economics,and has significant effects in most scenarios.However,the suitability and effectiveness of different hypothesis testing methods vary depending on the context,often leading to different outcomes and levels of accuracy.This paper focuses on discussing various hypothesis testing methods in statistics,such as t-test,chi-square test,z-test,F-test,etc.In addition,this study analyzes various cases in real life and optimize and improve some hypothesis testing methods.Based on a review of existing literature,the study explores how traditional hypothesis testing determines statistical significance—where the null hypothesis is rejected if the test statistic falls within the rejection region.To improve and enhance the determination of the significance level,handle uncertainty,and increase the sample size,this paper proposes alternative methods such as NHST test,Bayesian test,big data sequential test,and failure rate hypothesis test from the perspectives of medicine and kinesiology.
