In recent years,the escalation in accidental explosions has emerged as a formidable threat to tunnel infrastructures.Therefore,it is of great significance to conduct a dynamic performance analysis of the tunnels,to im...In recent years,the escalation in accidental explosions has emerged as a formidable threat to tunnel infrastructures.Therefore,it is of great significance to conduct a dynamic performance analysis of the tunnels,to improve the safety and maintain the functionality of underground transport hubs.To this end,this study proposes a dynamic performance assessment framework to assess the extent of damage of shallow buried circular tunnels under explosion hazards.First,the nonlinear dynamic finite element numerical model of soil-tunnel interaction system under explosion hazard was established and validated.Then,based on the validated numerical model,an explosion intensity(EI)considering both explosion equivalent and relative distance was used to further analyze the dynamic response characteristics under typical explosion conditions.Finally,this study further explored the influence of the integrity and strength of the surrounding soil,concrete strength,lining thickness,rebar strength,and rebar rate on the tunnel dynamic performance.Our results show that the dynamic performance assessment framework proposed for shallow circular tunnels fully integrates the coupling effects of explosion equivalent and distance,and is able to accurately measure the degree of damage sustained by these structures under different EI.This work contributes to designing and managing tunnels and underground transport networks based on dynamic performance,thereby facilitating decision-making and efficient allocation of resources by consultants,operators,and stakeholders.展开更多
With the increasing public consciousness on environmental issues, chemical products and process designs require simultaneous satisfaction and compromise of environmental and economical requirements. To fulfill the two...With the increasing public consciousness on environmental issues, chemical products and process designs require simultaneous satisfaction and compromise of environmental and economical requirements. To fulfill the two conflicting while complementary objectives, a systematic approach for life cycle design of a chemical product is proposed in this article. Multiattribute decision-making is adopted in a trade-off consideration of both technical economical evaluation and environmental impacts assessment using the analytic hierarchy process （AHP） approach. On the basis of an evaluation of the relative importance of the criteria multicriteria decision making is performed. In this study, an AHP model is used to derive single a criteria score by analyzing the environmental impact and life cycle cost of a product, respectively. And a fluctuant weight analysis is put forth to calculate the integrated index of the product to enable products to be ranked or selected intuitionally and conveniently. The proposed AHP model has been applied to a case study, a comparative study on chamber cleaning with NF3 and C2F6. The resuits show that the protposed AHP model is Capable of providing a rational and relevant evaluation.展开更多
The performance evaluation of the process industry, which has been a popular topic nowadays, can not only find the weakness and verify the resilience and reliability of the process, but also provide some suggestions t...The performance evaluation of the process industry, which has been a popular topic nowadays, can not only find the weakness and verify the resilience and reliability of the process, but also provide some suggestions to improve the process benefits and efficiency. Nevertheless, the performance assessment principally concentrates upon some parts of the entire system at present, for example the controller assessment. Although some researches focus on the whole process, they aim at discovering the relationships between profit, society, policies and so forth, instead of relations between overall performance and some manipulated variables, that is, the total plant performance. According to the big data of different performance statuses, this paper proposes a hierarchical framework to select some structured logic rules from monitored variables to estimate the current state of the process. The variables related to safety and profits are regarded as key factors to performance evaluation. To better monitor the process state and observe the performance variation trend of the process, a classificationvisualization method based on kernel principal component analysis(KPCA) and self-organizing map(SOM) is established. The dimensions of big data produced by the process are first reduced by KPCA and then the processed data will be mapped into a two-dimensional grid chart by SOM to evaluate the performance status. The monitoring method is applied to the Tennessee Eastman process. Monitoring results indicate that off-line and on-line performance status can be well detected in a two-dimensional diagram.展开更多
A route optimization methodology in the frame of an onboard decision support/guidance system for the ship＇s master has been developed and is presented in this paper. The method aims at the minimization of the fuel vo...A route optimization methodology in the frame of an onboard decision support/guidance system for the ship＇s master has been developed and is presented in this paper. The method aims at the minimization of the fuel voyage cost and the risks related to the ship＇s seakeeping performance expected to be within acceptable limits of voyage duration. Parts of this methodology were implemented by interfacing alternative probability assessment methods, such as Monte Carlo, first order reliability method （FORM） and second order reliability method （SORM）, and a 3-D seakeeping code, including a software tool for the calculation of the added resistance in waves of NTUA-SDL. The entire system was integrated within the probabilistic analysis software PROBAN. Two of the main modules for the calculation of added resistance and the probabilistic assessment for the considered seakeeping hazards with respect to exceedance levels of predefined threshold values are herein elaborated and validation studies proved their efficiency in view of their implementation into an on-board optimization system.展开更多
The computational grid provides a promising platform for the deployment of various high-performance computing applications. A grid system consists of heterogeneous resource domains, while the computational tasks of fi...The computational grid provides a promising platform for the deployment of various high-performance computing applications. A grid system consists of heterogeneous resource domains, while the computational tasks of finite element analysis may differ in demand of computing power. The cost-effective utilization of resources in the grid can be obtained through scheduling tasks to optimal resource domains. Firstly, a cost-effective scheduling strategy is presented for finite element applications. Secondly, aiming at the conjugate gradient solver stemming from finite element analysis, a performance evaluation formula is presented for determining optimal resouree domains, which is derived from phase parallel model and takes the heterogeneous characteristic of resource domains into account. Finally, experimental results show that the presented formula delivers a good estimation of the actual execution time, and indicate that the presented formula can be used to determine optimal resource domains in the grid environment.展开更多
Electrolytic manganese residue(EMR), a high volume byproduct resulting from the electrolytic manganese industry, was used as a cheap and abundant chemical source for preparing MnO2 and EMR-made calcium silicate hydrat...Electrolytic manganese residue(EMR), a high volume byproduct resulting from the electrolytic manganese industry, was used as a cheap and abundant chemical source for preparing MnO2 and EMR-made calcium silicate hydrate(EMR-CSH). The MnO2 is successfully synthesized from the metal cations extracted from EMR, which can effectively recycle the manganese in the EMR. By the combination of XRD, SEM and EDX analysis, the as-prepared MnO2 is found to exhibit a single-phase with the purity of 90.3%. Furthermore, EMR-CSH is synthesized from EMR via hydrothermal method. Based on the detailed analyses using XRD, FT-IR, FE-SEM, EDX and BET surface area measurement, the product synthesized under the optimum conditions(p H 12.0 and 100 °C) is identified to be a calcium silicate hydrate with a specific surface area of 205 m2/g incorporating the slag-derived metals(Al and Mg) in its structure. The as-synthesized material shows good adsorption properties for removal of Mn2+ and phosphate ions diluted in water, making it a promising candidate for efficient bulk wastewater treatment. This conversion process, which enables us to fabricate two different kinds of valuable materials from EMR at low cost and through convenient preparation steps, is surely beneficial from the viewpoint of the chemical and economical use of EMR.展开更多
Emergy analysis is effective for analyzing ecological economic systems. However, the accuracy of the approach is af- fected by the diversity of economic level, meteorological and hydrological parameters in different r...Emergy analysis is effective for analyzing ecological economic systems. However, the accuracy of the approach is af- fected by the diversity of economic level, meteorological and hydrological parameters in different regions. The present study evalu- ated the economic benefits, environmental impact, and sustainability of indoor, semi-intensive and extensive farming systems of sea cucumber （Apostichopus japonicus） in the same region. The results showed that A. japonicus indoor farming system was high in input and output （yield） whereas pond extensive farming system was low in input and output. The output/input ratio of indoor fann- ing system was lower than that of pond extensive farming system, and the output/input ratio of semi-intensive farming system fell in between them. The environmental loading ratio of A.japonicus extensive fanning system was lower than that of indoor farming sys- tem. In addition, the emergy yield and emergy exchange ratios, and emergy sustainability and emergy indexes for sustainable devel- opment were higher in extensive farming system than those in indoor farming system. These results indicated that the current exten- sive farming system exerted fewer negative influences on the environment, made more efficient use of available resources, and met more sustainable development requirements than the indoor farming system. A. japonicus farming systems showed more emergy benefits than fish fanning systems. The pond fanning systems ofA. japonicus exploited more free local environmental resources for production, caused less potential pressure on the local environment, and achieved higher sustainability than indoor farming system.展开更多
This paper is a comprehensive data collection and analysis of the special performance of the managed fund in provincial universities, which has very important academic value and theoretical and practical significance ...This paper is a comprehensive data collection and analysis of the special performance of the managed fund in provincial universities, which has very important academic value and theoretical and practical significance for the effective and rational improvement of the utilization ratio of the special funds, the specification of the management the university capitals and the ceaseless development of the education reform. It also has very important academic value and theoretical practical significance for the improvement of the financial management levels, the introduction of the evaluation results of the special funds into the budget appropriation mechanism, the refinement of the budget planning of the special funds, the improvement of the scientificalness and accuracy of the budget planning oft he special fimds, and the further strengthening of the management of the expenditure and balance of the special funds of universities, and the formulation of the scientific and effective performance evaluation methods, and the formation of the theoretical platform of the performance management evaluation.展开更多
Based on the objective management theory, this paper analyzes the existing problems in the process of government performance evaluation, explores the necessity of objective management in performance evaluation, and es...Based on the objective management theory, this paper analyzes the existing problems in the process of government performance evaluation, explores the necessity of objective management in performance evaluation, and establishes a government performance evaluation system based on objective management.展开更多
Because zirconium alloy cladding is the first containment barrier for fission products, its mechanical integrity is the most important concern. In view of the mechanical integrity, stress and strain are the main facto...Because zirconium alloy cladding is the first containment barrier for fission products, its mechanical integrity is the most important concern. In view of the mechanical integrity, stress and strain are the main factors that affect the cladding performance during normal or off-normal operation, which induces force interaction between the pellet and cladding. In the case of a normal operation period, to estimate the cladding stress and strain, various models and codes have been developed using a simplified 1D （one-dimensional） assumption. However, in the case of a slow ramp during start-up and shut-down and a fast transient such as an AOO （anticipated operational occurrence）, it is difficult for a 1D model to simulate the cladding stress and strain accurately due to its modeling limitation. To model a large deformation along the radial and axial directions such as a ＂＇ballooning＂ phenomenon, FE （finite element） modeling, which can simulate a higher degree of freedom, is an indispensable requirement. In this work, an axisymmetric two-dimensional FE module, which will be integrated into the transient fuel performance code, has been developed. To solve the mechanical equilibrium of the pellet-cladding system, taking into account the geometrical and material non-linearities, the FE module employs an ESF （effective-stress-function） algorithm. Verifications of the FE module for the cases of thermal and elastic analyes were performed using the results of ANSYS 13.0.展开更多
The purpose of this research is to identify and examine the achievement gaps between students. Over the past thirty years, emphasis has been placed on achievement levels of students in this country. State test results...The purpose of this research is to identify and examine the achievement gaps between students. Over the past thirty years, emphasis has been placed on achievement levels of students in this country. State test results, SAT Scores, ACT scores and other assessment instruments have been used to determine performance standards and test results for students. Data analyzed for White students compared to African American and Hispanic students have provided critical information in identifying academic progress and skill deficits for all students. This article will highlight some of the achievement gaps which exit among White, African American and Hispanic Students. Recommendations will also be emphasized to help improve student achievement levels in an effort to close the achievement gap.展开更多
The analysis used simple finite elements is performed to simulate the tensile behavior of corroded reinforcing bars extracted from three actual concrete structures. The cross-sectional area of the elements is set to h...The analysis used simple finite elements is performed to simulate the tensile behavior of corroded reinforcing bars extracted from three actual concrete structures. The cross-sectional area of the elements is set to have the actual distribution measured by 3D laser scanner system. The variable factor in the analysis is the length of the elements. The analysis results show that the length of the elements has a major influence on the deformation capacity after yielding. The calculated stress-strain curves, obtained using the elements with a length that is 2 times the bar diameter, are in good agreement with the tensile test results. The calculated stress-strain curves are modeled using a bi-linear model to facilitate the FEA （finite element analysis） of an overall concrete structure. From the analysis results, both the tensile and yield strengths decrease in proportion to the reduction of the minimum cross-sectional area of corroded bars. The ultimate strain has a remarkable decrement as the reduction of the minimum cross-sectional area. Formulas for determining these values are proposed as a function of the decrement ratio of the minimum cross-sectional area of a corroded bar.展开更多
Objective:To analyze the effect of acupuncture versus hormone replacement therapy(HRT)for premature ovarian insufficiency(POI).Methods:China National Knowledge Infrastructure(CNKI),Wanfang Academic Journal Full-text D...Objective:To analyze the effect of acupuncture versus hormone replacement therapy(HRT)for premature ovarian insufficiency(POI).Methods:China National Knowledge Infrastructure(CNKI),Wanfang Academic Journal Full-text Database(Wanfang),Chongqing VIP Database(CQVIP),China Biology Medicine Disc(CBM),Web of Science,Cochrane Library,PubMed,and Excerpta Medica Database(EMBASE)were searched up to January 31st,2019 to identify randomized controlled trials(RCTs)evaluating the effect of acupuncture for POI.The primary outcome was the level of basal serum follicle-stimulating hormone(FSH).Secondary outcomes included serum levels of luteinizing hormone(LH),estradiol(E2)and anti-Müllerian hormone(AMH).Two authors extracted data independently and assessed the risk of bias and the methodological quality using the Cochrane's tool.Meta-analysis was conducted by RevMan version 5.3.Results:Eight eligible RCTs with a total of 496 POI patients were included in the meta-analysis.The pooled results showed that there was a significant reduction in the basal serum FSH level(MD=-5.82,95%CI:-9.76 to-1.87,I2=82%,P=0.004)and a remarkable elevation in the basal E2 level(SMD=0.93,95%CI:0.34 to 1.52,I2=88%,P=0.002)in the acupuncture group when compared with the control.Subgroup analysis showed that compared with HRT,a significant decrease in the FSH level was observed in both acupuncture alone(MD=-4.53,95%CI:-8.96 to-0.10,I2=73%,P=0.04)and acupuncture plus HRT(MD=-9.60,95%CI:-17.60 to-1.61,I2=50%,P=0.02),while a remarkable elevation of E2 was only found in acupuncture plus HRT(SMD=1.43,95%CI:1.03 to 1.82,I2=0%,P<0.00001).There was no significant difference in the LH level between acupuncture and HRT(MD=-3.16,95%CI:-9.41 to 3.10,I2=0%,P=0.32),only one trial reported AMH,and no significant difference was found between acupuncture and HRT.Conclusion:The present study indicated that acupuncture had an advantage over HRT in reducing serum FSH level and increasing serum E2 level in women with POI.However,evidence supporting the finding is limited due to the small sample size,potential methodological flaws and significant heterogeneity.Hence,this conclusion still needs to be verified by high-quality RCTs.展开更多
基金Project(22dz1201202)supported by the Shanghai Science and Technology Committee Program,ChinaProjects(52108381,52090082)supported by the National Natural Science Foundation of China+1 种基金Project(2023QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST,ChinaProject(TSY2022QT161)supported by the Damage Database for Urban Rail Transit Underground Structures and Resilience Evaluation Algorithm Research。
文摘In recent years,the escalation in accidental explosions has emerged as a formidable threat to tunnel infrastructures.Therefore,it is of great significance to conduct a dynamic performance analysis of the tunnels,to improve the safety and maintain the functionality of underground transport hubs.To this end,this study proposes a dynamic performance assessment framework to assess the extent of damage of shallow buried circular tunnels under explosion hazards.First,the nonlinear dynamic finite element numerical model of soil-tunnel interaction system under explosion hazard was established and validated.Then,based on the validated numerical model,an explosion intensity(EI)considering both explosion equivalent and relative distance was used to further analyze the dynamic response characteristics under typical explosion conditions.Finally,this study further explored the influence of the integrity and strength of the surrounding soil,concrete strength,lining thickness,rebar strength,and rebar rate on the tunnel dynamic performance.Our results show that the dynamic performance assessment framework proposed for shallow circular tunnels fully integrates the coupling effects of explosion equivalent and distance,and is able to accurately measure the degree of damage sustained by these structures under different EI.This work contributes to designing and managing tunnels and underground transport networks based on dynamic performance,thereby facilitating decision-making and efficient allocation of resources by consultants,operators,and stakeholders.
基金Supported by the National Natural Science Foundation of China (No.20376025, No.20536020) the China Excellent YoungScientist Fund (No.20225620).
文摘With the increasing public consciousness on environmental issues, chemical products and process designs require simultaneous satisfaction and compromise of environmental and economical requirements. To fulfill the two conflicting while complementary objectives, a systematic approach for life cycle design of a chemical product is proposed in this article. Multiattribute decision-making is adopted in a trade-off consideration of both technical economical evaluation and environmental impacts assessment using the analytic hierarchy process （AHP） approach. On the basis of an evaluation of the relative importance of the criteria multicriteria decision making is performed. In this study, an AHP model is used to derive single a criteria score by analyzing the environmental impact and life cycle cost of a product, respectively. And a fluctuant weight analysis is put forth to calculate the integrated index of the product to enable products to be ranked or selected intuitionally and conveniently. The proposed AHP model has been applied to a case study, a comparative study on chamber cleaning with NF3 and C2F6. The resuits show that the protposed AHP model is Capable of providing a rational and relevant evaluation.
基金Supported by the National Natural Science Foundation of China(61590923,61422303,21376077)
文摘The performance evaluation of the process industry, which has been a popular topic nowadays, can not only find the weakness and verify the resilience and reliability of the process, but also provide some suggestions to improve the process benefits and efficiency. Nevertheless, the performance assessment principally concentrates upon some parts of the entire system at present, for example the controller assessment. Although some researches focus on the whole process, they aim at discovering the relationships between profit, society, policies and so forth, instead of relations between overall performance and some manipulated variables, that is, the total plant performance. According to the big data of different performance statuses, this paper proposes a hierarchical framework to select some structured logic rules from monitored variables to estimate the current state of the process. The variables related to safety and profits are regarded as key factors to performance evaluation. To better monitor the process state and observe the performance variation trend of the process, a classificationvisualization method based on kernel principal component analysis(KPCA) and self-organizing map(SOM) is established. The dimensions of big data produced by the process are first reduced by KPCA and then the processed data will be mapped into a two-dimensional grid chart by SOM to evaluate the performance status. The monitoring method is applied to the Tennessee Eastman process. Monitoring results indicate that off-line and on-line performance status can be well detected in a two-dimensional diagram.
基金supported by DNV in the framework of the GIFT strategic R&D collaboration agreement between DNV and the School of Naval Architecture and Marine Engineering of NTUA-Ship Design Laboratory
文摘A route optimization methodology in the frame of an onboard decision support/guidance system for the ship＇s master has been developed and is presented in this paper. The method aims at the minimization of the fuel voyage cost and the risks related to the ship＇s seakeeping performance expected to be within acceptable limits of voyage duration. Parts of this methodology were implemented by interfacing alternative probability assessment methods, such as Monte Carlo, first order reliability method （FORM） and second order reliability method （SORM）, and a 3-D seakeeping code, including a software tool for the calculation of the added resistance in waves of NTUA-SDL. The entire system was integrated within the probabilistic analysis software PROBAN. Two of the main modules for the calculation of added resistance and the probabilistic assessment for the considered seakeeping hazards with respect to exceedance levels of predefined threshold values are herein elaborated and validation studies proved their efficiency in view of their implementation into an on-board optimization system.
文摘The computational grid provides a promising platform for the deployment of various high-performance computing applications. A grid system consists of heterogeneous resource domains, while the computational tasks of finite element analysis may differ in demand of computing power. The cost-effective utilization of resources in the grid can be obtained through scheduling tasks to optimal resource domains. Firstly, a cost-effective scheduling strategy is presented for finite element applications. Secondly, aiming at the conjugate gradient solver stemming from finite element analysis, a performance evaluation formula is presented for determining optimal resouree domains, which is derived from phase parallel model and takes the heterogeneous characteristic of resource domains into account. Finally, experimental results show that the presented formula delivers a good estimation of the actual execution time, and indicate that the presented formula can be used to determine optimal resource domains in the grid environment.
基金Project(21376273)supported by the National Natural Science Foundation of ChinaProject(2010FJ1011)supported by the Research Fund of Science and Technology of Hunan Province,China
文摘Electrolytic manganese residue(EMR), a high volume byproduct resulting from the electrolytic manganese industry, was used as a cheap and abundant chemical source for preparing MnO2 and EMR-made calcium silicate hydrate(EMR-CSH). The MnO2 is successfully synthesized from the metal cations extracted from EMR, which can effectively recycle the manganese in the EMR. By the combination of XRD, SEM and EDX analysis, the as-prepared MnO2 is found to exhibit a single-phase with the purity of 90.3%. Furthermore, EMR-CSH is synthesized from EMR via hydrothermal method. Based on the detailed analyses using XRD, FT-IR, FE-SEM, EDX and BET surface area measurement, the product synthesized under the optimum conditions(p H 12.0 and 100 °C) is identified to be a calcium silicate hydrate with a specific surface area of 205 m2/g incorporating the slag-derived metals(Al and Mg) in its structure. The as-synthesized material shows good adsorption properties for removal of Mn2+ and phosphate ions diluted in water, making it a promising candidate for efficient bulk wastewater treatment. This conversion process, which enables us to fabricate two different kinds of valuable materials from EMR at low cost and through convenient preparation steps, is surely beneficial from the viewpoint of the chemical and economical use of EMR.
基金supported by the Key R & D Program (2011BAD13B03)the National Marine Public Welfare Project of China (200905020)the program for Excellent Youth Foundation of Shandong province (Grant No. JQ201009)
文摘Emergy analysis is effective for analyzing ecological economic systems. However, the accuracy of the approach is af- fected by the diversity of economic level, meteorological and hydrological parameters in different regions. The present study evalu- ated the economic benefits, environmental impact, and sustainability of indoor, semi-intensive and extensive farming systems of sea cucumber （Apostichopus japonicus） in the same region. The results showed that A. japonicus indoor farming system was high in input and output （yield） whereas pond extensive farming system was low in input and output. The output/input ratio of indoor fann- ing system was lower than that of pond extensive farming system, and the output/input ratio of semi-intensive farming system fell in between them. The environmental loading ratio of A.japonicus extensive fanning system was lower than that of indoor farming sys- tem. In addition, the emergy yield and emergy exchange ratios, and emergy sustainability and emergy indexes for sustainable devel- opment were higher in extensive farming system than those in indoor farming system. These results indicated that the current exten- sive farming system exerted fewer negative influences on the environment, made more efficient use of available resources, and met more sustainable development requirements than the indoor farming system. A. japonicus farming systems showed more emergy benefits than fish fanning systems. The pond fanning systems ofA. japonicus exploited more free local environmental resources for production, caused less potential pressure on the local environment, and achieved higher sustainability than indoor farming system.
文摘This paper is a comprehensive data collection and analysis of the special performance of the managed fund in provincial universities, which has very important academic value and theoretical and practical significance for the effective and rational improvement of the utilization ratio of the special funds, the specification of the management the university capitals and the ceaseless development of the education reform. It also has very important academic value and theoretical practical significance for the improvement of the financial management levels, the introduction of the evaluation results of the special funds into the budget appropriation mechanism, the refinement of the budget planning of the special funds, the improvement of the scientificalness and accuracy of the budget planning oft he special fimds, and the further strengthening of the management of the expenditure and balance of the special funds of universities, and the formulation of the scientific and effective performance evaluation methods, and the formation of the theoretical platform of the performance management evaluation.
文摘Based on the objective management theory, this paper analyzes the existing problems in the process of government performance evaluation, explores the necessity of objective management in performance evaluation, and establishes a government performance evaluation system based on objective management.
文摘Because zirconium alloy cladding is the first containment barrier for fission products, its mechanical integrity is the most important concern. In view of the mechanical integrity, stress and strain are the main factors that affect the cladding performance during normal or off-normal operation, which induces force interaction between the pellet and cladding. In the case of a normal operation period, to estimate the cladding stress and strain, various models and codes have been developed using a simplified 1D （one-dimensional） assumption. However, in the case of a slow ramp during start-up and shut-down and a fast transient such as an AOO （anticipated operational occurrence）, it is difficult for a 1D model to simulate the cladding stress and strain accurately due to its modeling limitation. To model a large deformation along the radial and axial directions such as a ＂＇ballooning＂ phenomenon, FE （finite element） modeling, which can simulate a higher degree of freedom, is an indispensable requirement. In this work, an axisymmetric two-dimensional FE module, which will be integrated into the transient fuel performance code, has been developed. To solve the mechanical equilibrium of the pellet-cladding system, taking into account the geometrical and material non-linearities, the FE module employs an ESF （effective-stress-function） algorithm. Verifications of the FE module for the cases of thermal and elastic analyes were performed using the results of ANSYS 13.0.
文摘The purpose of this research is to identify and examine the achievement gaps between students. Over the past thirty years, emphasis has been placed on achievement levels of students in this country. State test results, SAT Scores, ACT scores and other assessment instruments have been used to determine performance standards and test results for students. Data analyzed for White students compared to African American and Hispanic students have provided critical information in identifying academic progress and skill deficits for all students. This article will highlight some of the achievement gaps which exit among White, African American and Hispanic Students. Recommendations will also be emphasized to help improve student achievement levels in an effort to close the achievement gap.
文摘The analysis used simple finite elements is performed to simulate the tensile behavior of corroded reinforcing bars extracted from three actual concrete structures. The cross-sectional area of the elements is set to have the actual distribution measured by 3D laser scanner system. The variable factor in the analysis is the length of the elements. The analysis results show that the length of the elements has a major influence on the deformation capacity after yielding. The calculated stress-strain curves, obtained using the elements with a length that is 2 times the bar diameter, are in good agreement with the tensile test results. The calculated stress-strain curves are modeled using a bi-linear model to facilitate the FEA （finite element analysis） of an overall concrete structure. From the analysis results, both the tensile and yield strengths decrease in proportion to the reduction of the minimum cross-sectional area of corroded bars. The ultimate strain has a remarkable decrement as the reduction of the minimum cross-sectional area. Formulas for determining these values are proposed as a function of the decrement ratio of the minimum cross-sectional area of a corroded bar.
文摘Objective:To analyze the effect of acupuncture versus hormone replacement therapy(HRT)for premature ovarian insufficiency(POI).Methods:China National Knowledge Infrastructure(CNKI),Wanfang Academic Journal Full-text Database(Wanfang),Chongqing VIP Database(CQVIP),China Biology Medicine Disc(CBM),Web of Science,Cochrane Library,PubMed,and Excerpta Medica Database(EMBASE)were searched up to January 31st,2019 to identify randomized controlled trials(RCTs)evaluating the effect of acupuncture for POI.The primary outcome was the level of basal serum follicle-stimulating hormone(FSH).Secondary outcomes included serum levels of luteinizing hormone(LH),estradiol(E2)and anti-Müllerian hormone(AMH).Two authors extracted data independently and assessed the risk of bias and the methodological quality using the Cochrane's tool.Meta-analysis was conducted by RevMan version 5.3.Results:Eight eligible RCTs with a total of 496 POI patients were included in the meta-analysis.The pooled results showed that there was a significant reduction in the basal serum FSH level(MD=-5.82,95%CI:-9.76 to-1.87,I2=82%,P=0.004)and a remarkable elevation in the basal E2 level(SMD=0.93,95%CI:0.34 to 1.52,I2=88%,P=0.002)in the acupuncture group when compared with the control.Subgroup analysis showed that compared with HRT,a significant decrease in the FSH level was observed in both acupuncture alone(MD=-4.53,95%CI:-8.96 to-0.10,I2=73%,P=0.04)and acupuncture plus HRT(MD=-9.60,95%CI:-17.60 to-1.61,I2=50%,P=0.02),while a remarkable elevation of E2 was only found in acupuncture plus HRT(SMD=1.43,95%CI:1.03 to 1.82,I2=0%,P<0.00001).There was no significant difference in the LH level between acupuncture and HRT(MD=-3.16,95%CI:-9.41 to 3.10,I2=0%,P=0.32),only one trial reported AMH,and no significant difference was found between acupuncture and HRT.Conclusion:The present study indicated that acupuncture had an advantage over HRT in reducing serum FSH level and increasing serum E2 level in women with POI.However,evidence supporting the finding is limited due to the small sample size,potential methodological flaws and significant heterogeneity.Hence,this conclusion still needs to be verified by high-quality RCTs.
