Background Both medication and non-medication therapies are effective approaches to control blood pressure (BP) in hypertension patients.However,the association of joint changes in antihypertensive medication use and ...Background Both medication and non-medication therapies are effective approaches to control blood pressure (BP) in hypertension patients.However,the association of joint changes in antihypertensive medication use and healthy lifestyle index (HLI)with BP control among hypertension patients is seldom reported,which needs to provide more evidence by prospective intervention studies.We examined the association of antihypertensive medication use and HLI with BP control among employees with hypertension in China based on a workplace-based multicomponent intervention program.Methods Between January 2013 and December 2014,a cluster randomized clinical trial of a workplace-based multicomponent intervention program was conducted in 60 workplaces across 20 urban areas in China.Workplaces were randomly divided into intervention (n=40) and control (n=20) groups.Basic information on employees at each workplace was collected by trained professionals,including sociodemographic characteristics,medical history,family history,lifestyle behaviors,medication status and physical measurements.After baseline,the intervention group received a 2-year intervention to achieve BP control,which included:(1) a workplace wellness program for all employees;(2) a guidelines-oriented hypertension management protocol.HLI including nonsmoking,nondrinking,adequate physical activity,weight within reference range and balanced diet,were coded on a 5-point scale (range:0-5,with higher score indicating a healthier lifestyle).Antihypertensive medication use was defined as taking drug within the last 2 weeks.Changes in HLI,antihypertensive medication use and BP control from baseline to 24 months were measured after the intervention.Results Overall,4655 employees were included (age:46.3±7.6 years,men:3547 (82.3%)).After 24 months of the intervention,there was a significant improvement in lifestyle[smoking (OR=0.65,95%CI:0.43-0.99;P=0.045),drinking (OR=0.52,95%CI:0.40-0.68;P<0.001),regular exercise (OR=3.10,95%CI:2.53-3.78;P<0.001),excessive intake of fatty food (OR=0.17,95%CI:0.06-0.52;P=0.002),restrictive use of salt (OR=0.26,95%CI:0.12-0.56;P=0.001)].Compare to employees with a deteriorating lifestyle after the intervention,those with an improved lifestyle had a higher BP control.In the intervention group,compared with employees not using antihypertensive medication,those who consistent used (OR=2.34;95%CI:1.16-4.72;P=0.017) or changed from not using to using antihypertensive medication (OR=2.24;95%CI:1.08-4.62;P=0.030) had higher BP control.Compared with those having lower HLI,participants with a same (OR=1.38;95%CI:0.99-1.93;P=0.056) or high (OR=1.79;95%CI:1.27~2.53;P<0.001) HLI had higher BP control.Those who used antihypertensive medication and had a high HLI had the highest BP control (OR=1.88;95%CI:1.32-2.67,P<0.001).Subgroup analysis also showed the consistent effect as the above.Conclusion These findings suggest that adherence to antihypertensive medication treatment and healthy lifestyle were associated with a significant improvement in BP control among employees with hypertension.展开更多
A computer program PRETTA “Pressurizer Transient Thermodynamics Analysis” was developed for the prediction of pressurizer under transient conditions. It is based on the solution of the conservation laws of heat and ...A computer program PRETTA “Pressurizer Transient Thermodynamics Analysis” was developed for the prediction of pressurizer under transient conditions. It is based on the solution of the conservation laws of heat and mass applied to the three separate and non equilibrium thermodynamic regions. In the program all of the important thermal-hydraulics phenomena occurring in the pressurizer: stratification of the hot water and incoming cold water, bulk flashing and condensation, wall condensation, and interfacial heat and mass transfer have been considered. The bubble rising and rain-out models are developed to describe bulk flashing and condensation, respectively. To obtain the wall condensation rate, a one-dimensional heat conduction equation is solved by the pivoting method. The presented computer program will predict the pressure-time behavior of a PWR pressurizer during a variety of transients. The results obtained from the proposed mathematical model are in good agreement with available data on the CHASHMA nuclear power plant's pressurizer performance.展开更多
A type of single neuron adaptive PID regulator with auto-tuning gain is proposed and applied to the work control of fans, waterpumps and air-pressers etc. in Handan Iron & Steel Compel China. The robusthess of ind...A type of single neuron adaptive PID regulator with auto-tuning gain is proposed and applied to the work control of fans, waterpumps and air-pressers etc. in Handan Iron & Steel Compel China. The robusthess of induStrial parameter closed-loop process controlsystems is improved, and the work quality of the systems bettered.展开更多
Objectives:Pressure ulcer(PU)is one of the most common problem among the bedridden elderly and has significantly more burden on elderly and caregivers.This study is aimed to evaluate the effects of the training progra...Objectives:Pressure ulcer(PU)is one of the most common problem among the bedridden elderly and has significantly more burden on elderly and caregivers.This study is aimed to evaluate the effects of the training program for caregivers to prevent PUs among elderly residents at geriatric homes.Methods:A quasi-experimental design was used to carry out the current study.A purposive sample comprised of all formal(39 nurses)or informal caregivers(39)and all immobilized elderly residents(35)who are found in all geriatric centers in Helwan district.A structured questionnaire was used to assess caregivers’socio-demographic characteristics,knowledge,attitude,and observational checklists for their practice for prevention of PU at pre-and posttest and during follow-up.Results:After the training program,there were improvements in the level of knowledge,practice,and positive attitude of caregivers about PU prevention with a statistically significant difference between pre-,post-,and follow-up training programs(P<0.001).Conclusions:The study revealed that the training program seemed to change the knowledge,practice,and attitude of the subjects to PU prevention.This,in turn,implies that adequate knowledge affects directly the elderly caregivers’attitudes as well as practice for prevention could be important in reducing the burden of PU among the elderly.Thus,conducting a training program for caregivers at different geriatric homes about caring skills for elders can prevent PU,and using spontaneous reposition is very effective to prevent PUs.展开更多
Accurate gas viscosity determination is an important issue in the oil and gas industries.Experimental approaches for gas viscosity measurement are timeconsuming,expensive and hardly possible at high pressures and high...Accurate gas viscosity determination is an important issue in the oil and gas industries.Experimental approaches for gas viscosity measurement are timeconsuming,expensive and hardly possible at high pressures and high temperatures(HPHT).In this study,a number of correlations were developed to estimate gas viscosity by the use of group method of data handling(GMDH)type neural network and gene expression programming(GEP)techniques using a large data set containing more than 3000 experimental data points for methane,nitrogen,and hydrocarbon gas mixtures.It is worth mentioning that unlike many of viscosity correlations,the proposed ones in this study could compute gas viscosity at pressures ranging between 34 and 172 MPa and temperatures between 310 and 1300 K.Also,a comparison was performed between the results of these established models and the results of ten wellknown models reported in the literature.Average absolute relative errors of GMDH models were obtained 4.23%,0.64%,and 0.61%for hydrocarbon gas mixtures,methane,and nitrogen,respectively.In addition,graphical analyses indicate that the GMDH can predict gas viscosity with higher accuracy than GEP at HPHT conditions.Also,using leverage technique,valid,suspected and outlier data points were determined.Finally,trends of gas viscosity models at different conditions were evaluated.展开更多
Well Wutan 1 is a wildcat well deployed in the DazhoueKaijiang paleo-uplift,eastern Sichuan Basin and its design depth is 7570 m.The Cambrian and Sinian strata are its main exploration targets,and the strata below the...Well Wutan 1 is a wildcat well deployed in the DazhoueKaijiang paleo-uplift,eastern Sichuan Basin and its design depth is 7570 m.The Cambrian and Sinian strata are its main exploration targets,and the strata below the Silurian in this well are geologically uncertain with a high risk.A large section of gypsum-salt layer may be encountered in the Cambrian and the longitudinal pressure system is complex.It is predicted that the bottom hole temperature is up to 175 C,and the bottom hole liquid column pressure exceeds 140 MPa,and there is hydrogen sulfide.As a result,the casing program design is confronted with great challenges.In this paper,the difficulties and risks of drilling engineering were analyzed.Then,a casing program was designed and optimized referring to the successful drilling experience of subsalt ultra-deep wells at home and abroad,combined with the pressure system characteristics of Well Wutan 1 and the creep performance of gypsum-salt layers.Finally,the casing program was applied on site.And the following research results were obtained.First,in order to prevent lost circulation,blowout and differential pressure induced stuck pipe in the open hole section,it is determined that the casing program shall be in the pattern of six-section casing with 5 setting points.Second,no setting point is needed in the Carboniferous pressure depleted reservoir for it is lithologically tight and differential pressure induced stuck pipe and lost circulation are less risky.Third,to better isolate the salt layer,one section of casing is specially designed for the Cambrian gypsum-salt layer and its collapse strength is 160 MPa to prevent collapse by salt creep.Fourth,Well Wutan 1 is drilled successfully to the expected strata and its total depth is 8060 m.In conclusion,the unconventional six-section casing program with 5 setting points to ensure the subsalt drilling safety in the eastern Sichuan Basin is rational.The successful drilling of Well Wutan 1 provides experiences and references for the follow-up exploration of deep-seated gas in the DazhoueKaijiang paleo-uplift.展开更多
Good practices of maintenance optimization in nuclear power field need to be effectively consolidated and inherited,and maintenance optimization can provide technology support to create a long-term reliable and econom...Good practices of maintenance optimization in nuclear power field need to be effectively consolidated and inherited,and maintenance optimization can provide technology support to create a long-term reliable and economic operation for nuclear power plants( NPPs) especially for a large number of nuclear powers under construction. Based on the development and application of maintenance template in developed countries,and combining with reliability-centered maintenance( RCM) analysis results and maintenance experience data over the past ten years in domestic NPPs, the development process of maintenance template was presented for Chinese pressurized water reactor( PWR) NPP,and the application of maintenance template to maintenance program development and maintenance optimization combined with cases were demonstrated. A shortcut was provided for improving the efficiency of maintenance optimization in domestic PWR NPP,and help to realize a safe,reliable,and economic operation for domestic NPPs.展开更多
Objectives Most medical instruments are designed for diagnosis purpose but very few for clinical treatment. Our research aim is to design and develop a cardiovascular automatic feedback control instrument （CAFCI） fo...Objectives Most medical instruments are designed for diagnosis purpose but very few for clinical treatment. Our research aim is to design and develop a cardiovascular automatic feedback control instrument （CAFCI） for rescuing the critical patients with abnormal blood pressure. Methods The CAFCI was designed on the basis of abundant clinical experiences and on successful mathematic modeling of our blood pressure, pulmonary experimental data. The capillary wedge pressure, and rates of heart beat were measured and inputted into a computer and drugs were chosen by a doctor through a user-friendly interface with the computer. The responses to medication were rapidly acquired and feed back to the computer by automatic detection system in a close-loop system. every 7.5 sec in order to dosage The data were refreshed regulate the speed and of the medications that were given. Results The experimental results with ten dogs showed that the CAFCI system took samples promptly and accurately so that the targeted blood pressure could be reached reliably based on our input parameters and our designing requirements. Conclusions Since the dependability and accuracy of the CAFCI system are much superior to that of the traditional method, its clinical application to rescue the critical patient warrants evaluation in the future.展开更多
A class of closed-loop supply chain system consisting of one manufacturer and one supplier is designed, in which re-distribution, remanufacturing and reuse are considered synthetically. The manufacturer is in charge o...A class of closed-loop supply chain system consisting of one manufacturer and one supplier is designed, in which re-distribution, remanufacturing and reuse are considered synthetically. The manufacturer is in charge of recollecting and re-disposal the used products. Demands of ultimate products and collecting quantity of used products are described as the function of prices and reference prices. A non-linear dynamic pricing model for this closed-loop supply chain is established. A numerical example is designed, and the results of this example verified the model’s validity to price for the operation of closed-loop supply chain system.展开更多
This paper investigates and analyzes the current situation of young teachers in ten universities in Shaanxi via questionnaire survey and random interview. It is shown that the main source of pressure include the follo...This paper investigates and analyzes the current situation of young teachers in ten universities in Shaanxi via questionnaire survey and random interview. It is shown that the main source of pressure include the following aspects ： heavy burden of education and research, high-pressure in economy and life, high expectations of personal development, lack of physical exercise, mechanization of college evaluation system. On the basis of the above analysis, this paper puts forward the specific EAP model which is suitable to young teachers in NWPU Furtherly, the program impact assessment method is constructed to ensure the effective implementation of the program展开更多
水锤效应一直是核电厂热工安全所关注的重要问题之一。准确获得水锤效应下压力波的传播数据对结构载荷分析和评价至关重要。目前,常见水锤分析程序多采用的是特征线法(Method Of Characteristics,MOC),但其在处理多管道复杂系统和捕捉...水锤效应一直是核电厂热工安全所关注的重要问题之一。准确获得水锤效应下压力波的传播数据对结构载荷分析和评价至关重要。目前,常见水锤分析程序多采用的是特征线法(Method Of Characteristics,MOC),但其在处理多管道复杂系统和捕捉不连续性方面存在一定的计算误差。而有限体积法(Finite Volume Method,FVM)在计算复杂系统水锤问题上存在优势,典型程序为RELAP5。对此,本文基于FVM初步开发了一款水锤压力波传播分析程序。针对具体的单相水锤问题,发展了一种“汽-液”可压缩两流体三方程模型,并采用了以压力迭代为核心的时间步分割三步算法,对于单相水锤问题而言,本文开发的程序比RELAP5相关模型及算法更精炼、高效。通过单相水激波管基准例题开展了程序验证,将新开发程序的模拟结果与RELAP5程序结果和解析解进行对比。结果表明,新开发的程序在模拟水锤压力瞬变时数值耗散相对较低,初步验证了模型和算法的可行性和准确性。相关研究成果可为核电厂反应堆水锤分析与评价提供一定的理论与方法学支撑。展开更多
基金supported by grant 2011BAI11B01 from the Projects in the Chinese National Science and Technology Pillar Program during the 12th Five-year Plan Periodby grant 2017-I2M-1-004 from the Chinese Academy of Medical Science Innovation Fund for Medical Sciencesby the Major science and technology special plan project of Yunnan Province (202302AA310045)。
文摘Background Both medication and non-medication therapies are effective approaches to control blood pressure (BP) in hypertension patients.However,the association of joint changes in antihypertensive medication use and healthy lifestyle index (HLI)with BP control among hypertension patients is seldom reported,which needs to provide more evidence by prospective intervention studies.We examined the association of antihypertensive medication use and HLI with BP control among employees with hypertension in China based on a workplace-based multicomponent intervention program.Methods Between January 2013 and December 2014,a cluster randomized clinical trial of a workplace-based multicomponent intervention program was conducted in 60 workplaces across 20 urban areas in China.Workplaces were randomly divided into intervention (n=40) and control (n=20) groups.Basic information on employees at each workplace was collected by trained professionals,including sociodemographic characteristics,medical history,family history,lifestyle behaviors,medication status and physical measurements.After baseline,the intervention group received a 2-year intervention to achieve BP control,which included:(1) a workplace wellness program for all employees;(2) a guidelines-oriented hypertension management protocol.HLI including nonsmoking,nondrinking,adequate physical activity,weight within reference range and balanced diet,were coded on a 5-point scale (range:0-5,with higher score indicating a healthier lifestyle).Antihypertensive medication use was defined as taking drug within the last 2 weeks.Changes in HLI,antihypertensive medication use and BP control from baseline to 24 months were measured after the intervention.Results Overall,4655 employees were included (age:46.3±7.6 years,men:3547 (82.3%)).After 24 months of the intervention,there was a significant improvement in lifestyle[smoking (OR=0.65,95%CI:0.43-0.99;P=0.045),drinking (OR=0.52,95%CI:0.40-0.68;P<0.001),regular exercise (OR=3.10,95%CI:2.53-3.78;P<0.001),excessive intake of fatty food (OR=0.17,95%CI:0.06-0.52;P=0.002),restrictive use of salt (OR=0.26,95%CI:0.12-0.56;P=0.001)].Compare to employees with a deteriorating lifestyle after the intervention,those with an improved lifestyle had a higher BP control.In the intervention group,compared with employees not using antihypertensive medication,those who consistent used (OR=2.34;95%CI:1.16-4.72;P=0.017) or changed from not using to using antihypertensive medication (OR=2.24;95%CI:1.08-4.62;P=0.030) had higher BP control.Compared with those having lower HLI,participants with a same (OR=1.38;95%CI:0.99-1.93;P=0.056) or high (OR=1.79;95%CI:1.27~2.53;P<0.001) HLI had higher BP control.Those who used antihypertensive medication and had a high HLI had the highest BP control (OR=1.88;95%CI:1.32-2.67,P<0.001).Subgroup analysis also showed the consistent effect as the above.Conclusion These findings suggest that adherence to antihypertensive medication treatment and healthy lifestyle were associated with a significant improvement in BP control among employees with hypertension.
文摘A computer program PRETTA “Pressurizer Transient Thermodynamics Analysis” was developed for the prediction of pressurizer under transient conditions. It is based on the solution of the conservation laws of heat and mass applied to the three separate and non equilibrium thermodynamic regions. In the program all of the important thermal-hydraulics phenomena occurring in the pressurizer: stratification of the hot water and incoming cold water, bulk flashing and condensation, wall condensation, and interfacial heat and mass transfer have been considered. The bubble rising and rain-out models are developed to describe bulk flashing and condensation, respectively. To obtain the wall condensation rate, a one-dimensional heat conduction equation is solved by the pivoting method. The presented computer program will predict the pressure-time behavior of a PWR pressurizer during a variety of transients. The results obtained from the proposed mathematical model are in good agreement with available data on the CHASHMA nuclear power plant's pressurizer performance.
文摘A type of single neuron adaptive PID regulator with auto-tuning gain is proposed and applied to the work control of fans, waterpumps and air-pressers etc. in Handan Iron & Steel Compel China. The robusthess of induStrial parameter closed-loop process controlsystems is improved, and the work quality of the systems bettered.
文摘Objectives:Pressure ulcer(PU)is one of the most common problem among the bedridden elderly and has significantly more burden on elderly and caregivers.This study is aimed to evaluate the effects of the training program for caregivers to prevent PUs among elderly residents at geriatric homes.Methods:A quasi-experimental design was used to carry out the current study.A purposive sample comprised of all formal(39 nurses)or informal caregivers(39)and all immobilized elderly residents(35)who are found in all geriatric centers in Helwan district.A structured questionnaire was used to assess caregivers’socio-demographic characteristics,knowledge,attitude,and observational checklists for their practice for prevention of PU at pre-and posttest and during follow-up.Results:After the training program,there were improvements in the level of knowledge,practice,and positive attitude of caregivers about PU prevention with a statistically significant difference between pre-,post-,and follow-up training programs(P<0.001).Conclusions:The study revealed that the training program seemed to change the knowledge,practice,and attitude of the subjects to PU prevention.This,in turn,implies that adequate knowledge affects directly the elderly caregivers’attitudes as well as practice for prevention could be important in reducing the burden of PU among the elderly.Thus,conducting a training program for caregivers at different geriatric homes about caring skills for elders can prevent PU,and using spontaneous reposition is very effective to prevent PUs.
文摘Accurate gas viscosity determination is an important issue in the oil and gas industries.Experimental approaches for gas viscosity measurement are timeconsuming,expensive and hardly possible at high pressures and high temperatures(HPHT).In this study,a number of correlations were developed to estimate gas viscosity by the use of group method of data handling(GMDH)type neural network and gene expression programming(GEP)techniques using a large data set containing more than 3000 experimental data points for methane,nitrogen,and hydrocarbon gas mixtures.It is worth mentioning that unlike many of viscosity correlations,the proposed ones in this study could compute gas viscosity at pressures ranging between 34 and 172 MPa and temperatures between 310 and 1300 K.Also,a comparison was performed between the results of these established models and the results of ten wellknown models reported in the literature.Average absolute relative errors of GMDH models were obtained 4.23%,0.64%,and 0.61%for hydrocarbon gas mixtures,methane,and nitrogen,respectively.In addition,graphical analyses indicate that the GMDH can predict gas viscosity with higher accuracy than GEP at HPHT conditions.Also,using leverage technique,valid,suspected and outlier data points were determined.Finally,trends of gas viscosity models at different conditions were evaluated.
基金supported by Major Science and Technology Project of PetroChina Company Limited“Research and application of key exploration and devel opment technologies to achieve 30-billion-m3 production in Southwest Oil and Gas Field”(No.:2016E-0608)Major Science and Technology Project of Southwest Oil&Gas Field Company“Research and application of key gas exploration and development technologies for Eastern Sichuan Basin”(No.:2016ZD01).
文摘Well Wutan 1 is a wildcat well deployed in the DazhoueKaijiang paleo-uplift,eastern Sichuan Basin and its design depth is 7570 m.The Cambrian and Sinian strata are its main exploration targets,and the strata below the Silurian in this well are geologically uncertain with a high risk.A large section of gypsum-salt layer may be encountered in the Cambrian and the longitudinal pressure system is complex.It is predicted that the bottom hole temperature is up to 175 C,and the bottom hole liquid column pressure exceeds 140 MPa,and there is hydrogen sulfide.As a result,the casing program design is confronted with great challenges.In this paper,the difficulties and risks of drilling engineering were analyzed.Then,a casing program was designed and optimized referring to the successful drilling experience of subsalt ultra-deep wells at home and abroad,combined with the pressure system characteristics of Well Wutan 1 and the creep performance of gypsum-salt layers.Finally,the casing program was applied on site.And the following research results were obtained.First,in order to prevent lost circulation,blowout and differential pressure induced stuck pipe in the open hole section,it is determined that the casing program shall be in the pattern of six-section casing with 5 setting points.Second,no setting point is needed in the Carboniferous pressure depleted reservoir for it is lithologically tight and differential pressure induced stuck pipe and lost circulation are less risky.Third,to better isolate the salt layer,one section of casing is specially designed for the Cambrian gypsum-salt layer and its collapse strength is 160 MPa to prevent collapse by salt creep.Fourth,Well Wutan 1 is drilled successfully to the expected strata and its total depth is 8060 m.In conclusion,the unconventional six-section casing program with 5 setting points to ensure the subsalt drilling safety in the eastern Sichuan Basin is rational.The successful drilling of Well Wutan 1 provides experiences and references for the follow-up exploration of deep-seated gas in the DazhoueKaijiang paleo-uplift.
文摘Good practices of maintenance optimization in nuclear power field need to be effectively consolidated and inherited,and maintenance optimization can provide technology support to create a long-term reliable and economic operation for nuclear power plants( NPPs) especially for a large number of nuclear powers under construction. Based on the development and application of maintenance template in developed countries,and combining with reliability-centered maintenance( RCM) analysis results and maintenance experience data over the past ten years in domestic NPPs, the development process of maintenance template was presented for Chinese pressurized water reactor( PWR) NPP,and the application of maintenance template to maintenance program development and maintenance optimization combined with cases were demonstrated. A shortcut was provided for improving the efficiency of maintenance optimization in domestic PWR NPP,and help to realize a safe,reliable,and economic operation for domestic NPPs.
文摘Objectives Most medical instruments are designed for diagnosis purpose but very few for clinical treatment. Our research aim is to design and develop a cardiovascular automatic feedback control instrument （CAFCI） for rescuing the critical patients with abnormal blood pressure. Methods The CAFCI was designed on the basis of abundant clinical experiences and on successful mathematic modeling of our blood pressure, pulmonary experimental data. The capillary wedge pressure, and rates of heart beat were measured and inputted into a computer and drugs were chosen by a doctor through a user-friendly interface with the computer. The responses to medication were rapidly acquired and feed back to the computer by automatic detection system in a close-loop system. every 7.5 sec in order to dosage The data were refreshed regulate the speed and of the medications that were given. Results The experimental results with ten dogs showed that the CAFCI system took samples promptly and accurately so that the targeted blood pressure could be reached reliably based on our input parameters and our designing requirements. Conclusions Since the dependability and accuracy of the CAFCI system are much superior to that of the traditional method, its clinical application to rescue the critical patient warrants evaluation in the future.
文摘A class of closed-loop supply chain system consisting of one manufacturer and one supplier is designed, in which re-distribution, remanufacturing and reuse are considered synthetically. The manufacturer is in charge of recollecting and re-disposal the used products. Demands of ultimate products and collecting quantity of used products are described as the function of prices and reference prices. A non-linear dynamic pricing model for this closed-loop supply chain is established. A numerical example is designed, and the results of this example verified the model’s validity to price for the operation of closed-loop supply chain system.
基金fund by High Education Research Fund of Northwestern Polytechnical University(2014)
文摘This paper investigates and analyzes the current situation of young teachers in ten universities in Shaanxi via questionnaire survey and random interview. It is shown that the main source of pressure include the following aspects ： heavy burden of education and research, high-pressure in economy and life, high expectations of personal development, lack of physical exercise, mechanization of college evaluation system. On the basis of the above analysis, this paper puts forward the specific EAP model which is suitable to young teachers in NWPU Furtherly, the program impact assessment method is constructed to ensure the effective implementation of the program
文摘水锤效应一直是核电厂热工安全所关注的重要问题之一。准确获得水锤效应下压力波的传播数据对结构载荷分析和评价至关重要。目前,常见水锤分析程序多采用的是特征线法(Method Of Characteristics,MOC),但其在处理多管道复杂系统和捕捉不连续性方面存在一定的计算误差。而有限体积法(Finite Volume Method,FVM)在计算复杂系统水锤问题上存在优势,典型程序为RELAP5。对此,本文基于FVM初步开发了一款水锤压力波传播分析程序。针对具体的单相水锤问题,发展了一种“汽-液”可压缩两流体三方程模型,并采用了以压力迭代为核心的时间步分割三步算法,对于单相水锤问题而言,本文开发的程序比RELAP5相关模型及算法更精炼、高效。通过单相水激波管基准例题开展了程序验证,将新开发程序的模拟结果与RELAP5程序结果和解析解进行对比。结果表明,新开发的程序在模拟水锤压力瞬变时数值耗散相对较低,初步验证了模型和算法的可行性和准确性。相关研究成果可为核电厂反应堆水锤分析与评价提供一定的理论与方法学支撑。
