The activation and the resulting response of the immune system to antigens comprise different complex processes and cells. This paper aims at modeling the processes of recognition and learning of the immune system by ...The activation and the resulting response of the immune system to antigens comprise different complex processes and cells. This paper aims at modeling the processes of recognition and learning of the immune system by means of the thermostatted kinetic theory methods. Specifically, the thermostatted kinetic framework is firstly generalized for taking into account that in some processes of proliferation of the cells, the rate is also function of the degree of information exchanged amongst cells. In particular, within the new framework, a mathematical model is proposed for miming the recognition process of the immune system through the definition of interactions between the cytoto^ic and humoral components of the adaptive immune system via T- and B-cells. The model validation is obtained by performing a sensitivity analysis on the parameters which depicts the main emerging phenomena and the different phases of the recognition and learning of the immune system.展开更多
As the development of new power systems progresses,the inherent inertia of power systems continues to diminish.Centralized frequency regulation,which relies on rapid communication and real-time control,can enable inve...As the development of new power systems progresses,the inherent inertia of power systems continues to diminish.Centralized frequency regulation,which relies on rapid communication and real-time control,can enable inverter-based thermostatically controlled load(ITCL)clusters to provide virtual inertia support to the power grid.However,ITCL clusters exhibit significant discrete response characteristics,which precludes the direct integration of load-side inertia support into the synchronous unit side.To address this issue,this paper elaborates on the existing technical framework and analyzes the underlying causes of the problem.It proposes a timestamp allocation mechanism for ITCL cluster control instructions,ensuring that many ITCL terminals can be triggered at staggered times,thereby allowing the load cluster power to adhere to the inertia analog control law at any moment.Building on this foundation,the paper further examines the impact of the inertia response delay of ITCL clusters,which is based on centralized frequency regulation,on the stability of the power system.A design scheme for inertia analog control parameters is proposed,taking into account dual constraints,frequency stability and load cluster regulation capacity.Finally,the feasibility and applicability of the proposed mechanism and parameter design scheme are investigated through simulations conducted via MATLAB/Simulink.展开更多
In order to study the relationship between charge size and thermal initiation critical temperature of explosive in defined conditions,cook-off test about JH explosive was carried out at a heating rate of 1 ℃/min usin...In order to study the relationship between charge size and thermal initiation critical temperature of explosive in defined conditions,cook-off test about JH explosive was carried out at a heating rate of 1 ℃/min using self-designed cook-off experiment setup based on thermostatic control technology.Numerical simulation was conducted to study the effects of different charge sizes on thermal initiation critical temperature of explosives with FLUENT software.Experiment results show that there is a thermal initiation critical temperature in cook-off bomb.Simulation results show that when the ratio of the length to diameter of explosives grains is a fixed value,the thermal initiation critical temperature of explosives decreases with the increase of the diameter of explosives grains.When the grains diameter of explosives increase up to a certain value,the influence of charge size on thermal initiation critical temperature tends to be weakened.Charge size has no influence on the ignition point of explosives.The ignition point is always in the center of the grain.展开更多
This paper presents a fiber optic temperature measuring system used for measuring the temperature in many occasions. The system is of reflective type and composed of thermostatic bimetal plate, lever piston framewo...This paper presents a fiber optic temperature measuring system used for measuring the temperature in many occasions. The system is of reflective type and composed of thermostatic bimetal plate, lever piston framework, optical grating and optical fiber probes. When the temperature changes, the thermostatic bimetal plate deforms. Through lever piston framework, the optical grating produces displacement in the upright direction. Thus the change of the temperature is transformed into the upright displacement of the optical grating. Optical fiber probes are used for detecting the number of streak lines of the optical grating′s displacement depending on the change of temperature. The detected signal can be transmitted to the control center through optical fiber cable up to distance of 1 km. The measurable range of this system reaches 100℃ with accuracy of ±0.2℃.展开更多
The existing fundamental laws of thermodynamics for micropolar continuum field theories are restudied and their incompleteness is pointed out. New first and second fundamental laws for thermostatics and thermodynamics...The existing fundamental laws of thermodynamics for micropolar continuum field theories are restudied and their incompleteness is pointed out. New first and second fundamental laws for thermostatics and thermodynamics for micropolar continua are postulated. From them all equilibrium equations and the entropy inequality of thermostatics as well as all balance equations and the entropy rate inequalities are naturally and simultaneously deduced. The comparisons between the new results presented here and the corresponding results demonstrated in existing monographs and textbooks concerning micropolar continuum mechanics are made at any time. It should be emphasized to note that, the problem of why the local balance equation of energy and the local entropy inequality could not be obtained from the existing fundamental laws of thermodynamics for micropolar continua, is believed to be clarified.展开更多
How to freely control heat transfer at macroscopic scale is always a dream of human beings due to important applications in thermal protection,detection,and control/management.Within the past decade(2008-2018),thermal...How to freely control heat transfer at macroscopic scale is always a dream of human beings due to important applications in thermal protection,detection,and control/management.Within the past decade(2008-2018),thermal metamaterials have been shown as a promising candidate for this purpose.Here,I review the up-to-date research progress in the field,which mainly includes the following novel phenomena and functional devices together with initial applications:thermal cloak,concentrator,dual function,thermal rotator,macroscopic thermal diode,thermal camouflage,thermal transparency,thermal crystal,energy-free thermostat,abnormal conduction in networks,convection cloak/concentrator/camouflage,and thermal radiation cooling.The underlying mechanisms are presented according to six categories of theory:transformation thermotics,direct solution of Laplace equation,energy band theory,phase transition theory,transformation thermal convection,and thermal radiation theory.I also introduce and comment their prospects from fundamental research to industrial applications.This review has relevance to novel controls of heat transfer(conduction,convection,and radiation)by using artificial structures or devices.展开更多
Heating by electricity rather than coal is considered one effective way to reduce environmental problems. Thus, the electric heating load is growing rapidly, which may cause undesired problems in distribution grids be...Heating by electricity rather than coal is considered one effective way to reduce environmental problems. Thus, the electric heating load is growing rapidly, which may cause undesired problems in distribution grids because of the randomness and dispersed integration of the load. However, the electric heating load may also function as an energy storage system with optimal operational control. Therefore, the optimal modeling of electric heating load characteristics, considering its randomness, is important for grid planning and construction. In this study, the heating loads of distributed residential users in a certain area are modeled based on the Fanger thermal comfort equation and the predicted mean vote thermal comfort index calculation method. Different temperatures are considered while modeling the users' heating loads. The heat load demand curve is estimated according to the time-varying equation of interior temperature. A multi-objective optimization model for the electric heating load with heat energy storage is then studied considering the demand response(DR), which optimizes economy and the comfort index. A fuzzy decision method is proposed, considering the factors influencing DR behavior. Finally, the validity of the proposed model is verified by simulations. The results show that the proposed model performs better than the traditional method.展开更多
Accurate and efficient integration of the equations of motion is indispensable for molecular dynamics(MD)simulations.Despite the massive use of the conventional leapfrog(LF)integrator in modern computational tools wit...Accurate and efficient integration of the equations of motion is indispensable for molecular dynamics(MD)simulations.Despite the massive use of the conventional leapfrog(LF)integrator in modern computational tools within the framework of MD propagation,further development for better performance is still possible.The alternative version of LF in the middle thermostat scheme(LFmiddle)achieves a higher order of accuracy and efficiency and maintains stable dynamics even with the integration time stepsize extended by several folds.In this work,we perform a benchmark test of the two integrators(LF and LF-middle)in extensive conventional and enhanced sampling simulations,aiming at quantifying the time-stepsizeinduced variations of global properties(e.g.,detailed potential energy terms)as well as of local observables(e.g.,free energy changes or bondlengths)in practical simulations of complex systems.The test set is composed of six chemically and biologically relevant systems,including the conformational change of dihedral flipping in the N-methylacetamide and an AT(AdenineThymine)tract,the intra-molecular proton transfer inside malonaldehyde,the binding free energy calculations of benzene and phenol targeting T4 lysozyme L99A,the hydroxyl bond variations in ethaline deep eutectic solvent,and the potential energy of the blue-light using flavin photoreceptor.It is observed that the time-step-induced error is smaller for the LFmiddle scheme.The outperformance of LF-middle over the conventional LF integrator is much more significant for global properties than local observables.Overall,the current work demonstrates that the LF-middle scheme should be preferably applied to obtain accurate thermodynamics in the simulation of practical chemical and biological systems.展开更多
Molecular dynamics with the stochastic process provides a convenient way to compute structural and thermodynamic properties of chemical, biological, and materials systems. It is demonstrated that the virtual dynamics ...Molecular dynamics with the stochastic process provides a convenient way to compute structural and thermodynamic properties of chemical, biological, and materials systems. It is demonstrated that the virtual dynamics case that we proposed for the Langevin equation [J. Chem. Phys. 147, 184104 （2017）] in principle exists in other types of stochastic thermostats as well. The recommended ＂middle＂ scheme [J. Chem. Phys. 147, 034109 （2017）] of the Andersen thermostat is investigated as an example. As shown by both analytic and numerical results, while the real and virtual dynamics cases approach the same plateau of the characteristic correlation time in the high collision frequency limit, the accuracy and efficiency of sampling are relatively insensitive to the value of the collision frequency in a broad range. After we compare the behaviors of the Andersen thermostat to those of Langevin dynamics, a heuristic schematic representation thermostatting processes with molecular is proposed for understanding efficient stochastic dynamics.展开更多
Molecular-dynamics(MD)simulations have been performed for the growth of a spherical methane-hydrate nano-crystallite,surrounded by a supersaturated water–methane liquid phase,using both a hybrid and globalsystem ther...Molecular-dynamics(MD)simulations have been performed for the growth of a spherical methane-hydrate nano-crystallite,surrounded by a supersaturated water–methane liquid phase,using both a hybrid and globalsystem thermostatting approach.It was found that hybrid thermostatting led to more sluggish growth and the establishment of a radial temperature profile about the spherical hydrate crystallite,in which the growing crystal phase is at a higher temperature than the surrounding liquid phase in the interfacial region,owing to latent-heat dissipation.In addition,Onsager’s-hypothesis fluctuation–dissipation analysis of fluctuations in the number of crystal-state water molecules at the interface shows slower growth.展开更多
The designed thermostat is based on the microcontroller featuring intelligence, programmable, environmental protection and power saving. The thermostat design is mainly composed of hardware and software design, the ha...The designed thermostat is based on the microcontroller featuring intelligence, programmable, environmental protection and power saving. The thermostat design is mainly composed of hardware and software design, the hardware includes the power supply circuit, temperature measurement circuit, humidity measurement circuit and backlight circuit; while the software design includes temperature measurement and compensation algorithm, moreover software flowchart is given as well. Finally the power supply circuit is simulated by the software of Pspice and the creative power stealing mode is verified by the simulation results. A target board is stuffed by hand with Pb-free electronic components and used to test hardware and debug software. Since the Pb-free components were used, power stealing mode is designed in hardware and temperature compensation algorithm is accomplished in software, and the thermostat is outstanding with its features of "green" and "power saving".展开更多
In this paper, single-walled carbon nanotubes （SWCNTs） are studied through molecular dynamics （MD） simulation. The simulations are performed at temperatures of 1 and 300K separately, with atomic interactions chara...In this paper, single-walled carbon nanotubes （SWCNTs） are studied through molecular dynamics （MD） simulation. The simulations are performed at temperatures of 1 and 300K separately, with atomic interactions characterized by the second Reactive Empirical Bond Order （REBO） potential, and temperature controlled by a certain thermostat, i.e. by separately using the velocity scaling, the Berendsen scheme, the Nose-Hoover scheme, and the generalized Langevin scheme. Results for a （5,5） SWCNT with a length of 24.5 nm show apparent distortions in nanotube configuration, which can further enter into periodic vibrations, except in simulations using the generalized Langevin thermostat, which is ascribed to periodic boundary conditions used in simulation. The periodic boundary conditions may implicitly be applied in the form of an inconsistent constraint along the axis of the nanotube. The combination of the inconsistent constraint with the cumulative errors in calculation causes the distortions of nanotubes. When the generalized Langevin thermostat is applied, inconsistently distributed errors are dispersed by the random forces, and so the distortions and vibrations disappear. This speculation is confirmed by simulation in the case without periodic boundary conditions, where no apparent distortion and vibration occur. It is also revealed that numerically induced distortions and vibrations occur only in simulation of nanotubes with a small diameter and a large length-to-diameter ratio. When MD simulation is applied to a system with a particular geometry, attention should be paid to avoiding the numerical distortion and the result infidelity.展开更多
In this paper, the impact of limiting thermostat on the rupture event occuring in Fuel-Oil burner fuel pre-heaters＇ resistant （heat generating） wires is inspected numerically. Gaseous fuel content in the pipeline h...In this paper, the impact of limiting thermostat on the rupture event occuring in Fuel-Oil burner fuel pre-heaters＇ resistant （heat generating） wires is inspected numerically. Gaseous fuel content in the pipeline has also been issued as a possibility. Heater＇s inner temperature distributions have been simulated by an in-house MATrix LABoratory （MATLAB） script in order to understand the resistant wire exposure to high temperatures by numerous scenarios. It is concluded that the effect of fuel flowrate is not a major effect on the wires＇ fate because of the limiting thermostat co-working. The main difference between the calculations is the effect of thermostat cut off function. The numerical simulations enlightened the dominant effect of thermostat sensing delay, so the overheating event. Intolerable delay results with a quick drop in the thermal efficiency and an increased possibility on wire rupture due to overheating which means a burner malfunction. Referring to the first numerical simulation results, a distributed and reduced heat flux was implemented with the same fluid and thermodynamic properties on a revised pre-heater model with an increased heater plate. The increment, thus the reduction on the heat flux of the ribbon wires has been noted as the key for safe operation.展开更多
The paper demonstrates deep unity of classic and quantum physics at the space thermostat (ST) presence, which fulfilled all space by the temperature T0 = 2.73 K. The ST presents itself the Cosmic Microwave Background ...The paper demonstrates deep unity of classic and quantum physics at the space thermostat (ST) presence, which fulfilled all space by the temperature T0 = 2.73 K. The ST presents itself the Cosmic Microwave Background (CMB). From the main quantum position we consider the ST/CMB as the wave function carrier (“quantum background”). The paper is devoted to ST/CMB medium the classic conservation laws of mass, momentum and energy. We show the soliton like solutions of our classic model correspond to Schrodinger’s quantum solutions, demonstrate the atom hydrogen specter and other quantum peculiarities. The paper contains typical technical examples classic/ quantum simulation at the ST presence.展开更多
https://www.sciencedirect.com/journal/energy-and-buildings/vol/212/suppl/C Volume 212,1 April 2020(1)Assessment of the impact of HVAC system configuration and control zoning on thermal comfort and energy efficiency in...https://www.sciencedirect.com/journal/energy-and-buildings/vol/212/suppl/C Volume 212,1 April 2020(1)Assessment of the impact of HVAC system configuration and control zoning on thermal comfort and energy efficiency in flexible office spaces,by Jasmin Anika Grtner,Francesco Massa Gray,Thomas Auer,Article 109785Abstract:In office buildings,the space layout usually needs to be repeatedly redesigned in order to meet tenants’requirements during the building’s life cycle.In this study,the effect of a flexible space layout design on thermal comfort and energy demand is investigated in a modern open-plan office space.Using dynamic thermal simulation.展开更多
Innovatively addressing the challenge of difficult winter starts for vehicles in northern regions,this study has developed a Thermally Controlled Preheating Engine Activation System.This system ingeniously integrates ...Innovatively addressing the challenge of difficult winter starts for vehicles in northern regions,this study has developed a Thermally Controlled Preheating Engine Activation System.This system ingeniously integrates a thermal insulation kettle,an efficient water pump,precision valves,and temperature sensors,all closely linked with the engine’s coolant circulation system.In cold environments,the system automatically initiates a preheating mechanism by circulating and heating the coolant,significantly enhancing engine startup efficiency and reducing wear caused by cold starts.The anticipated outcome of this research is to substantially improve the operational reliability of vehicles in cold climates,extend their lifespan,promote energy conservation and emissions reduction,and drive the automotive industry towards greener,more efficient,and intelligent technologies,thus laying a solid foundation for industry upgrades and transformation.展开更多
The worldwide energy shortage and environmental pollution increase the demand for energy-free passive thermal management.However,current passive temperature regulation systems lack adaptive capacity,and achieving prec...The worldwide energy shortage and environmental pollution increase the demand for energy-free passive thermal management.However,current passive temperature regulation systems lack adaptive capacity,and achieving precise temperature control is challenging.Herein,we propose and design a passive thermostat comprising a thermal-responsive poly(N-isopropylacrylamide)hydrogel upper layer and a photothermal conversion bottom layer.The phase transition behavior of the thermal-responsive hydrogel results in reversible transparent and opaque states and allows a corresponding switchable solar heating and cooling process,thus fulfilling a thermostat function featuring designable and stable temperatures.By adjusting the low critical solution temperature(LCST)of the upper hydrogel layer,the passive thermostat’s temperature can be precisely predesigned equal to the LCST in the open air,which is in the range of 30-38℃.The passive thermostat can maintain a temperature variance of approximately 0.287℃ over 3 h in cold winter.Additionally,the thermostat can maintain a stable and relatively low temperature on extremely hot summer days,owing to the switching off solar heating capacity.These results underscore the potential of using clean,renewable solar resources for effective thermal management with stable and precise temperature controls.展开更多
Thermostatically controlled loads(TCLs)have huge thermal inertia and are promising resources to promote consumption of renewable energy sources(RESs)for carbon reduction.Thus,this paper employs the virtual power plant...Thermostatically controlled loads(TCLs)have huge thermal inertia and are promising resources to promote consumption of renewable energy sources(RESs)for carbon reduction.Thus,this paper employs the virtual power plant(VPP)to regulate TCLs to address problems caused by RESs.Specifically,a two-stage VPP scheduling framework based on multi-time scale coordinated control of TCLs is proposed to address forecast errors of variable RES power output.In the first stage(hour time scale),TCLs are controlled as virtual generators to mitigate forecast errors between hour-ahead and day-ahead RES power.In the second stage(minute time scale),TCLs are regulated as virtual batteries to mitigate forecast errors between intra-hour and hour-ahead RES power.To respect wills and preferences of end-users,a transactive energy(TE)market within VPP is built to guide TCL behaviors via the price mechanism.Moreover,a stochastic VPP schedule using the Wassersteinmetric-based distributionally robust optimization method is developed to consider RES power uncertainties,and its solution process is transformed into a computationally tractable mixedinteger linear programming problem based on the affine decision rule and duality theory.The proposed method is effectively validated by comparison with robust optimization and stochastic optimization.Simulation results demonstrate the proposed twostage VPP scheduling method employs TCL flexibilities more comprehensively to mitigate RES output power forecast errors in VPP operations.展开更多
Heating,ventilation,and air conditioning system runtime is a crucial metric for establishing the connection between system operation and energy performance.Similar homes in the same location can have varying runtime d...Heating,ventilation,and air conditioning system runtime is a crucial metric for establishing the connection between system operation and energy performance.Similar homes in the same location can have varying runtime due to different factors.To understand such heterogeneity,this study conducted an energy signature analysis of heating and cooling system runtime for 5,014 homes across the US>using data from ecobee smart thermostats.Two approaches were compared for the energy signature analysis:(1)using daily mean outdoor temperature and(2)using the difference between the daily mean outdoor temperature and the indoor thermostat setpoint(delta T)as the independent variable.The best-fitting energy signature parameters(balance temperatures and slopes)for each house were estimated and statistically analyzed.The results revealed significant differences in balance temperatures and slopes across various climates and individual homes.Additionally,we identified the impact of housing characteristics and weather conditions on the energy signature parameters using a long absolute shrinkage and selection operator(LASSO)regression.Incorporating delta T into the energy signature model significantly enhances its ability to detect hidden impacts of various features by minimizing the influence of setpoint preferences.Moreover,our cooling slope analysis highlights the significant impact of outdoor humidity levels,underscoring the need to include latent loads in building energy models.展开更多
文摘The activation and the resulting response of the immune system to antigens comprise different complex processes and cells. This paper aims at modeling the processes of recognition and learning of the immune system by means of the thermostatted kinetic theory methods. Specifically, the thermostatted kinetic framework is firstly generalized for taking into account that in some processes of proliferation of the cells, the rate is also function of the degree of information exchanged amongst cells. In particular, within the new framework, a mathematical model is proposed for miming the recognition process of the immune system through the definition of interactions between the cytoto^ic and humoral components of the adaptive immune system via T- and B-cells. The model validation is obtained by performing a sensitivity analysis on the parameters which depicts the main emerging phenomena and the different phases of the recognition and learning of the immune system.
基金supported by the Key Scientific and Technological Projects(2024KJGG27)of Tianfu Yongxing Laboratorythe Experimental Platform Open Innovation Funding(209042025003)of Sichuan Energy Internet Research Institute,Tsinghua University.
文摘As the development of new power systems progresses,the inherent inertia of power systems continues to diminish.Centralized frequency regulation,which relies on rapid communication and real-time control,can enable inverter-based thermostatically controlled load(ITCL)clusters to provide virtual inertia support to the power grid.However,ITCL clusters exhibit significant discrete response characteristics,which precludes the direct integration of load-side inertia support into the synchronous unit side.To address this issue,this paper elaborates on the existing technical framework and analyzes the underlying causes of the problem.It proposes a timestamp allocation mechanism for ITCL cluster control instructions,ensuring that many ITCL terminals can be triggered at staggered times,thereby allowing the load cluster power to adhere to the inertia analog control law at any moment.Building on this foundation,the paper further examines the impact of the inertia response delay of ITCL clusters,which is based on centralized frequency regulation,on the stability of the power system.A design scheme for inertia analog control parameters is proposed,taking into account dual constraints,frequency stability and load cluster regulation capacity.Finally,the feasibility and applicability of the proposed mechanism and parameter design scheme are investigated through simulations conducted via MATLAB/Simulink.
文摘In order to study the relationship between charge size and thermal initiation critical temperature of explosive in defined conditions,cook-off test about JH explosive was carried out at a heating rate of 1 ℃/min using self-designed cook-off experiment setup based on thermostatic control technology.Numerical simulation was conducted to study the effects of different charge sizes on thermal initiation critical temperature of explosives with FLUENT software.Experiment results show that there is a thermal initiation critical temperature in cook-off bomb.Simulation results show that when the ratio of the length to diameter of explosives grains is a fixed value,the thermal initiation critical temperature of explosives decreases with the increase of the diameter of explosives grains.When the grains diameter of explosives increase up to a certain value,the influence of charge size on thermal initiation critical temperature tends to be weakened.Charge size has no influence on the ignition point of explosives.The ignition point is always in the center of the grain.
文摘This paper presents a fiber optic temperature measuring system used for measuring the temperature in many occasions. The system is of reflective type and composed of thermostatic bimetal plate, lever piston framework, optical grating and optical fiber probes. When the temperature changes, the thermostatic bimetal plate deforms. Through lever piston framework, the optical grating produces displacement in the upright direction. Thus the change of the temperature is transformed into the upright displacement of the optical grating. Optical fiber probes are used for detecting the number of streak lines of the optical grating′s displacement depending on the change of temperature. The detected signal can be transmitted to the control center through optical fiber cable up to distance of 1 km. The measurable range of this system reaches 100℃ with accuracy of ±0.2℃.
基金Project supported by the National Natural Science Foundation of China (Nos. 10472041 and 10072024)the Science Research Foundation of Liaoning Province (No.990111001)
文摘The existing fundamental laws of thermodynamics for micropolar continuum field theories are restudied and their incompleteness is pointed out. New first and second fundamental laws for thermostatics and thermodynamics for micropolar continua are postulated. From them all equilibrium equations and the entropy inequality of thermostatics as well as all balance equations and the entropy rate inequalities are naturally and simultaneously deduced. The comparisons between the new results presented here and the corresponding results demonstrated in existing monographs and textbooks concerning micropolar continuum mechanics are made at any time. It should be emphasized to note that, the problem of why the local balance equation of energy and the local entropy inequality could not be obtained from the existing fundamental laws of thermodynamics for micropolar continua, is believed to be clarified.
基金financial support by the National Natural Science Foundation of China under Grant No.11725521the Science and Technology Commission of Shanghai Municipality under Grant No.16ZR1445100
文摘How to freely control heat transfer at macroscopic scale is always a dream of human beings due to important applications in thermal protection,detection,and control/management.Within the past decade(2008-2018),thermal metamaterials have been shown as a promising candidate for this purpose.Here,I review the up-to-date research progress in the field,which mainly includes the following novel phenomena and functional devices together with initial applications:thermal cloak,concentrator,dual function,thermal rotator,macroscopic thermal diode,thermal camouflage,thermal transparency,thermal crystal,energy-free thermostat,abnormal conduction in networks,convection cloak/concentrator/camouflage,and thermal radiation cooling.The underlying mechanisms are presented according to six categories of theory:transformation thermotics,direct solution of Laplace equation,energy band theory,phase transition theory,transformation thermal convection,and thermal radiation theory.I also introduce and comment their prospects from fundamental research to industrial applications.This review has relevance to novel controls of heat transfer(conduction,convection,and radiation)by using artificial structures or devices.
基金supported by the State Grid Science and Technology Project(No.52020118000M)
文摘Heating by electricity rather than coal is considered one effective way to reduce environmental problems. Thus, the electric heating load is growing rapidly, which may cause undesired problems in distribution grids because of the randomness and dispersed integration of the load. However, the electric heating load may also function as an energy storage system with optimal operational control. Therefore, the optimal modeling of electric heating load characteristics, considering its randomness, is important for grid planning and construction. In this study, the heating loads of distributed residential users in a certain area are modeled based on the Fanger thermal comfort equation and the predicted mean vote thermal comfort index calculation method. Different temperatures are considered while modeling the users' heating loads. The heat load demand curve is estimated according to the time-varying equation of interior temperature. A multi-objective optimization model for the electric heating load with heat energy storage is then studied considering the demand response(DR), which optimizes economy and the comfort index. A fuzzy decision method is proposed, considering the factors influencing DR behavior. Finally, the validity of the proposed model is verified by simulations. The results show that the proposed model performs better than the traditional method.
基金supported by the National Natural Science Foundation of China(No.21961142017)the Ministry of Science and Technology of China(No.2017YFA0204901)。
文摘Accurate and efficient integration of the equations of motion is indispensable for molecular dynamics(MD)simulations.Despite the massive use of the conventional leapfrog(LF)integrator in modern computational tools within the framework of MD propagation,further development for better performance is still possible.The alternative version of LF in the middle thermostat scheme(LFmiddle)achieves a higher order of accuracy and efficiency and maintains stable dynamics even with the integration time stepsize extended by several folds.In this work,we perform a benchmark test of the two integrators(LF and LF-middle)in extensive conventional and enhanced sampling simulations,aiming at quantifying the time-stepsizeinduced variations of global properties(e.g.,detailed potential energy terms)as well as of local observables(e.g.,free energy changes or bondlengths)in practical simulations of complex systems.The test set is composed of six chemically and biologically relevant systems,including the conformational change of dihedral flipping in the N-methylacetamide and an AT(AdenineThymine)tract,the intra-molecular proton transfer inside malonaldehyde,the binding free energy calculations of benzene and phenol targeting T4 lysozyme L99A,the hydroxyl bond variations in ethaline deep eutectic solvent,and the potential energy of the blue-light using flavin photoreceptor.It is observed that the time-step-induced error is smaller for the LFmiddle scheme.The outperformance of LF-middle over the conventional LF integrator is much more significant for global properties than local observables.Overall,the current work demonstrates that the LF-middle scheme should be preferably applied to obtain accurate thermodynamics in the simulation of practical chemical and biological systems.
文摘Molecular dynamics with the stochastic process provides a convenient way to compute structural and thermodynamic properties of chemical, biological, and materials systems. It is demonstrated that the virtual dynamics case that we proposed for the Langevin equation [J. Chem. Phys. 147, 184104 （2017）] in principle exists in other types of stochastic thermostats as well. The recommended ＂middle＂ scheme [J. Chem. Phys. 147, 034109 （2017）] of the Andersen thermostat is investigated as an example. As shown by both analytic and numerical results, while the real and virtual dynamics cases approach the same plateau of the characteristic correlation time in the high collision frequency limit, the accuracy and efficiency of sampling are relatively insensitive to the value of the collision frequency in a broad range. After we compare the behaviors of the Andersen thermostat to those of Langevin dynamics, a heuristic schematic representation thermostatting processes with molecular is proposed for understanding efficient stochastic dynamics.
基金the Irish Research Council for Government-of-Ireland postdoctoral fellowship, under grant no. GOIPD/2016/365
文摘Molecular-dynamics(MD)simulations have been performed for the growth of a spherical methane-hydrate nano-crystallite,surrounded by a supersaturated water–methane liquid phase,using both a hybrid and globalsystem thermostatting approach.It was found that hybrid thermostatting led to more sluggish growth and the establishment of a radial temperature profile about the spherical hydrate crystallite,in which the growing crystal phase is at a higher temperature than the surrounding liquid phase in the interfacial region,owing to latent-heat dissipation.In addition,Onsager’s-hypothesis fluctuation–dissipation analysis of fluctuations in the number of crystal-state water molecules at the interface shows slower growth.
基金Youth Research Start-up Fund of XinJiang University(QN070136)National Natural Science Foundation of China(50667002)
文摘The designed thermostat is based on the microcontroller featuring intelligence, programmable, environmental protection and power saving. The thermostat design is mainly composed of hardware and software design, the hardware includes the power supply circuit, temperature measurement circuit, humidity measurement circuit and backlight circuit; while the software design includes temperature measurement and compensation algorithm, moreover software flowchart is given as well. Finally the power supply circuit is simulated by the software of Pspice and the creative power stealing mode is verified by the simulation results. A target board is stuffed by hand with Pb-free electronic components and used to test hardware and debug software. Since the Pb-free components were used, power stealing mode is designed in hardware and temperature compensation algorithm is accomplished in software, and the thermostat is outstanding with its features of "green" and "power saving".
基金Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No 20060003025)the State Key Program for Basic Research of China (Grant No 2003CB716201)
文摘In this paper, single-walled carbon nanotubes （SWCNTs） are studied through molecular dynamics （MD） simulation. The simulations are performed at temperatures of 1 and 300K separately, with atomic interactions characterized by the second Reactive Empirical Bond Order （REBO） potential, and temperature controlled by a certain thermostat, i.e. by separately using the velocity scaling, the Berendsen scheme, the Nose-Hoover scheme, and the generalized Langevin scheme. Results for a （5,5） SWCNT with a length of 24.5 nm show apparent distortions in nanotube configuration, which can further enter into periodic vibrations, except in simulations using the generalized Langevin thermostat, which is ascribed to periodic boundary conditions used in simulation. The periodic boundary conditions may implicitly be applied in the form of an inconsistent constraint along the axis of the nanotube. The combination of the inconsistent constraint with the cumulative errors in calculation causes the distortions of nanotubes. When the generalized Langevin thermostat is applied, inconsistently distributed errors are dispersed by the random forces, and so the distortions and vibrations disappear. This speculation is confirmed by simulation in the case without periodic boundary conditions, where no apparent distortion and vibration occur. It is also revealed that numerically induced distortions and vibrations occur only in simulation of nanotubes with a small diameter and a large length-to-diameter ratio. When MD simulation is applied to a system with a particular geometry, attention should be paid to avoiding the numerical distortion and the result infidelity.
文摘In this paper, the impact of limiting thermostat on the rupture event occuring in Fuel-Oil burner fuel pre-heaters＇ resistant （heat generating） wires is inspected numerically. Gaseous fuel content in the pipeline has also been issued as a possibility. Heater＇s inner temperature distributions have been simulated by an in-house MATrix LABoratory （MATLAB） script in order to understand the resistant wire exposure to high temperatures by numerous scenarios. It is concluded that the effect of fuel flowrate is not a major effect on the wires＇ fate because of the limiting thermostat co-working. The main difference between the calculations is the effect of thermostat cut off function. The numerical simulations enlightened the dominant effect of thermostat sensing delay, so the overheating event. Intolerable delay results with a quick drop in the thermal efficiency and an increased possibility on wire rupture due to overheating which means a burner malfunction. Referring to the first numerical simulation results, a distributed and reduced heat flux was implemented with the same fluid and thermodynamic properties on a revised pre-heater model with an increased heater plate. The increment, thus the reduction on the heat flux of the ribbon wires has been noted as the key for safe operation.
文摘The paper demonstrates deep unity of classic and quantum physics at the space thermostat (ST) presence, which fulfilled all space by the temperature T0 = 2.73 K. The ST presents itself the Cosmic Microwave Background (CMB). From the main quantum position we consider the ST/CMB as the wave function carrier (“quantum background”). The paper is devoted to ST/CMB medium the classic conservation laws of mass, momentum and energy. We show the soliton like solutions of our classic model correspond to Schrodinger’s quantum solutions, demonstrate the atom hydrogen specter and other quantum peculiarities. The paper contains typical technical examples classic/ quantum simulation at the ST presence.
文摘https://www.sciencedirect.com/journal/energy-and-buildings/vol/212/suppl/C Volume 212,1 April 2020(1)Assessment of the impact of HVAC system configuration and control zoning on thermal comfort and energy efficiency in flexible office spaces,by Jasmin Anika Grtner,Francesco Massa Gray,Thomas Auer,Article 109785Abstract:In office buildings,the space layout usually needs to be repeatedly redesigned in order to meet tenants’requirements during the building’s life cycle.In this study,the effect of a flexible space layout design on thermal comfort and energy demand is investigated in a modern open-plan office space.Using dynamic thermal simulation.
文摘Innovatively addressing the challenge of difficult winter starts for vehicles in northern regions,this study has developed a Thermally Controlled Preheating Engine Activation System.This system ingeniously integrates a thermal insulation kettle,an efficient water pump,precision valves,and temperature sensors,all closely linked with the engine’s coolant circulation system.In cold environments,the system automatically initiates a preheating mechanism by circulating and heating the coolant,significantly enhancing engine startup efficiency and reducing wear caused by cold starts.The anticipated outcome of this research is to substantially improve the operational reliability of vehicles in cold climates,extend their lifespan,promote energy conservation and emissions reduction,and drive the automotive industry towards greener,more efficient,and intelligent technologies,thus laying a solid foundation for industry upgrades and transformation.
基金financially supported by the Natural Science Foundation of Jiangsu Province(BK20240027)。
文摘The worldwide energy shortage and environmental pollution increase the demand for energy-free passive thermal management.However,current passive temperature regulation systems lack adaptive capacity,and achieving precise temperature control is challenging.Herein,we propose and design a passive thermostat comprising a thermal-responsive poly(N-isopropylacrylamide)hydrogel upper layer and a photothermal conversion bottom layer.The phase transition behavior of the thermal-responsive hydrogel results in reversible transparent and opaque states and allows a corresponding switchable solar heating and cooling process,thus fulfilling a thermostat function featuring designable and stable temperatures.By adjusting the low critical solution temperature(LCST)of the upper hydrogel layer,the passive thermostat’s temperature can be precisely predesigned equal to the LCST in the open air,which is in the range of 30-38℃.The passive thermostat can maintain a temperature variance of approximately 0.287℃ over 3 h in cold winter.Additionally,the thermostat can maintain a stable and relatively low temperature on extremely hot summer days,owing to the switching off solar heating capacity.These results underscore the potential of using clean,renewable solar resources for effective thermal management with stable and precise temperature controls.
基金supported by the National Natural Science Foundation of China(52007030,52077136)Young Elite Scientists Sponsorship Program by Jiangsu Association for Scienceand Technology(TJ-2022-042).
文摘Thermostatically controlled loads(TCLs)have huge thermal inertia and are promising resources to promote consumption of renewable energy sources(RESs)for carbon reduction.Thus,this paper employs the virtual power plant(VPP)to regulate TCLs to address problems caused by RESs.Specifically,a two-stage VPP scheduling framework based on multi-time scale coordinated control of TCLs is proposed to address forecast errors of variable RES power output.In the first stage(hour time scale),TCLs are controlled as virtual generators to mitigate forecast errors between hour-ahead and day-ahead RES power.In the second stage(minute time scale),TCLs are regulated as virtual batteries to mitigate forecast errors between intra-hour and hour-ahead RES power.To respect wills and preferences of end-users,a transactive energy(TE)market within VPP is built to guide TCL behaviors via the price mechanism.Moreover,a stochastic VPP schedule using the Wassersteinmetric-based distributionally robust optimization method is developed to consider RES power uncertainties,and its solution process is transformed into a computationally tractable mixedinteger linear programming problem based on the affine decision rule and duality theory.The proposed method is effectively validated by comparison with robust optimization and stochastic optimization.Simulation results demonstrate the proposed twostage VPP scheduling method employs TCL flexibilities more comprehensively to mitigate RES output power forecast errors in VPP operations.
基金supported by the National Science Foundation(award OAC-2005572)the State of Illinois,USA.
文摘Heating,ventilation,and air conditioning system runtime is a crucial metric for establishing the connection between system operation and energy performance.Similar homes in the same location can have varying runtime due to different factors.To understand such heterogeneity,this study conducted an energy signature analysis of heating and cooling system runtime for 5,014 homes across the US>using data from ecobee smart thermostats.Two approaches were compared for the energy signature analysis:(1)using daily mean outdoor temperature and(2)using the difference between the daily mean outdoor temperature and the indoor thermostat setpoint(delta T)as the independent variable.The best-fitting energy signature parameters(balance temperatures and slopes)for each house were estimated and statistically analyzed.The results revealed significant differences in balance temperatures and slopes across various climates and individual homes.Additionally,we identified the impact of housing characteristics and weather conditions on the energy signature parameters using a long absolute shrinkage and selection operator(LASSO)regression.Incorporating delta T into the energy signature model significantly enhances its ability to detect hidden impacts of various features by minimizing the influence of setpoint preferences.Moreover,our cooling slope analysis highlights the significant impact of outdoor humidity levels,underscoring the need to include latent loads in building energy models.
