Nuclear power plants exhibit non-linear and time-variable dynamics.Therefore,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor...Nuclear power plants exhibit non-linear and time-variable dynamics.Therefore,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor(SCWR)is a fourth-generation conceptual reactor.In an SCWR,the non-linear dynamics of the reactor require a controller capable of control-ling the nonlinearities.In this study,a pressure-tube-type SCWR was controlled during reactor power maneuvering with a higher order sliding mode,and the reactor outgoing steam temperature and pressure were controlled simultaneously.In an SCWR,the temperature,pressure,and power must be maintained at a setpoint(desired value)during power maneuvering.Reactor point kinetics equations with three groups of delayed neutrons were used in the simulation.Higher-order and classic sliding mode controllers were separately manufactured to control the plant and were compared with the PI controllers speci-fied in previous studies.The controlled parameters were reactor power,steam temperature,and pressure.Notably,for these parameters,the PI controller had certain instabilities in the presence of disturbances.The classic sliding mode controller had a higher accuracy and stability;however its main drawback was the chattering phenomenon.HOSMC was highly accurate and stable and had a small computational cost.In reality,it followed the desired values without oscillations and chattering.展开更多
This study proposes a refined methodology for controlling building heights in heritage areas.In order to protect the visual integrity of the heritage area,buildings should not obstruct the view from important site poi...This study proposes a refined methodology for controlling building heights in heritage areas.In order to protect the visual integrity of the heritage area,buildings should not obstruct the view from important site points and viewpoints to the periphery.By calculating the building height thresholds that buildings should not obscure the view from each viewpoint,the results of which are weighted and superimposed,and the values are extracted to each building unit as a refined building height control guideline.This study takes the Zhoukoudian area as a case study,applies the refined building height control criterion to the Zhoukoudian Site,and relies on this refined criterion to assess the visual integrity of the Zhoukoudian area,so as to realize the scientific planning and monitoring of the Zhoukoudian area.The refined building height control method can be applied to building height planning and visual landscape protection in large heritage areas.展开更多
应用危害分析及关键控制点(Hazard Analysis and Critical Control Point,HACCP)体系的基本原理,结合虾滑的实际生产工艺,对生产过程中可能存在生物的、化学的、物理的危害进行分析和评估,最终确定原辅料验收、调味、金属探测3个关键控...应用危害分析及关键控制点(Hazard Analysis and Critical Control Point,HACCP)体系的基本原理,结合虾滑的实际生产工艺,对生产过程中可能存在生物的、化学的、物理的危害进行分析和评估,最终确定原辅料验收、调味、金属探测3个关键控制点,并制定相应的预防和控制措施,体系的运用可以有效、全面、系统地监控虾滑产品的质量,确保食品安全。展开更多
With the gradual acceleration of the urbanization process,the construction industry has been developing rapidly.As the key link to ensure the quality and safety of the project,construction management and construction ...With the gradual acceleration of the urbanization process,the construction industry has been developing rapidly.As the key link to ensure the quality and safety of the project,construction management and construction quality control are of great significance to enhance the competitiveness of construction enterprises and realize sustainable development.In this paper,the effective strategy of construction management and the effective strategy of construction quality control will be discussed in depth,aiming at providing useful management and quality control strategies for construction enterprises.展开更多
随着食品安全问题日益受到重视,危害分析与关键控制点(Hazard Analysis and Critical Control Point,HACCP)体系作为保障食品安全的重要手段,其有效实施与监控显得尤为重要。基于此,本文阐述了HACCP体系的内涵,分析了HACCP体系有效实施...随着食品安全问题日益受到重视,危害分析与关键控制点(Hazard Analysis and Critical Control Point,HACCP)体系作为保障食品安全的重要手段,其有效实施与监控显得尤为重要。基于此,本文阐述了HACCP体系的内涵,分析了HACCP体系有效实施的路径,包括建立前提条件、确定关键控制点、设立监控程序等。同时,分析了HACCP体系在实施监控中存在的问题,如企业重视程度不足、监控手段落后等,并针对这些问题提出了相应的改进建议,旨在为食品企业和监管部门提供一些参考和借鉴,促进食品安全管理水平的提升。展开更多
目的基于食用螺旋藻粉的市场安全需求分析食用螺旋藻粉生产过程中的风险因子并提出防控措施。方法根据危害分析和关键控制点(hazard analysis and critical control point,HACCP)体系原则分析生产过程中可能出现的问题,对各个环节进行...目的基于食用螺旋藻粉的市场安全需求分析食用螺旋藻粉生产过程中的风险因子并提出防控措施。方法根据危害分析和关键控制点(hazard analysis and critical control point,HACCP)体系原则分析生产过程中可能出现的问题,对各个环节进行危害分析并制定预防控制措施,对螺旋藻粉进行生物、物理、化学等方面的风险分析后,依据关键控制点(critical control point,CCP)判断树,对生产工艺的各个环节进行判断。结果确定了5个关键控制点,即CCP1–原辅料接收、CCP2–藻种接种、CCP3–养殖管理、CCP4–滤藻及清洗、CCP5–喷雾干燥,每一项关键控制点至少制定了一个关键限值,以消除其显著危害或将危害降低至可接受水平。结论螺旋藻的生长方式特殊,在生产过程中应严格执行HACCP体系,可以保证螺旋藻粉的质量和安全,为消费者的健康饮食提供保障。展开更多
文摘Nuclear power plants exhibit non-linear and time-variable dynamics.Therefore,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor(SCWR)is a fourth-generation conceptual reactor.In an SCWR,the non-linear dynamics of the reactor require a controller capable of control-ling the nonlinearities.In this study,a pressure-tube-type SCWR was controlled during reactor power maneuvering with a higher order sliding mode,and the reactor outgoing steam temperature and pressure were controlled simultaneously.In an SCWR,the temperature,pressure,and power must be maintained at a setpoint(desired value)during power maneuvering.Reactor point kinetics equations with three groups of delayed neutrons were used in the simulation.Higher-order and classic sliding mode controllers were separately manufactured to control the plant and were compared with the PI controllers speci-fied in previous studies.The controlled parameters were reactor power,steam temperature,and pressure.Notably,for these parameters,the PI controller had certain instabilities in the presence of disturbances.The classic sliding mode controller had a higher accuracy and stability;however its main drawback was the chattering phenomenon.HOSMC was highly accurate and stable and had a small computational cost.In reality,it followed the desired values without oscillations and chattering.
文摘This study proposes a refined methodology for controlling building heights in heritage areas.In order to protect the visual integrity of the heritage area,buildings should not obstruct the view from important site points and viewpoints to the periphery.By calculating the building height thresholds that buildings should not obscure the view from each viewpoint,the results of which are weighted and superimposed,and the values are extracted to each building unit as a refined building height control guideline.This study takes the Zhoukoudian area as a case study,applies the refined building height control criterion to the Zhoukoudian Site,and relies on this refined criterion to assess the visual integrity of the Zhoukoudian area,so as to realize the scientific planning and monitoring of the Zhoukoudian area.The refined building height control method can be applied to building height planning and visual landscape protection in large heritage areas.
文摘应用危害分析及关键控制点(Hazard Analysis and Critical Control Point,HACCP)体系的基本原理,结合虾滑的实际生产工艺,对生产过程中可能存在生物的、化学的、物理的危害进行分析和评估,最终确定原辅料验收、调味、金属探测3个关键控制点,并制定相应的预防和控制措施,体系的运用可以有效、全面、系统地监控虾滑产品的质量,确保食品安全。
文摘With the gradual acceleration of the urbanization process,the construction industry has been developing rapidly.As the key link to ensure the quality and safety of the project,construction management and construction quality control are of great significance to enhance the competitiveness of construction enterprises and realize sustainable development.In this paper,the effective strategy of construction management and the effective strategy of construction quality control will be discussed in depth,aiming at providing useful management and quality control strategies for construction enterprises.
文摘随着食品安全问题日益受到重视,危害分析与关键控制点(Hazard Analysis and Critical Control Point,HACCP)体系作为保障食品安全的重要手段,其有效实施与监控显得尤为重要。基于此,本文阐述了HACCP体系的内涵,分析了HACCP体系有效实施的路径,包括建立前提条件、确定关键控制点、设立监控程序等。同时,分析了HACCP体系在实施监控中存在的问题,如企业重视程度不足、监控手段落后等,并针对这些问题提出了相应的改进建议,旨在为食品企业和监管部门提供一些参考和借鉴,促进食品安全管理水平的提升。
文摘目的基于食用螺旋藻粉的市场安全需求分析食用螺旋藻粉生产过程中的风险因子并提出防控措施。方法根据危害分析和关键控制点(hazard analysis and critical control point,HACCP)体系原则分析生产过程中可能出现的问题,对各个环节进行危害分析并制定预防控制措施,对螺旋藻粉进行生物、物理、化学等方面的风险分析后,依据关键控制点(critical control point,CCP)判断树,对生产工艺的各个环节进行判断。结果确定了5个关键控制点,即CCP1–原辅料接收、CCP2–藻种接种、CCP3–养殖管理、CCP4–滤藻及清洗、CCP5–喷雾干燥,每一项关键控制点至少制定了一个关键限值,以消除其显著危害或将危害降低至可接受水平。结论螺旋藻的生长方式特殊,在生产过程中应严格执行HACCP体系,可以保证螺旋藻粉的质量和安全,为消费者的健康饮食提供保障。
