Controlling mass transportation using intrinsic mechanisms is a challenging topic in nanotechnology.Herein,we employ molecular dynamics simulations to investigate the mass transport inside carbon nanotubes(CNT)with te...Controlling mass transportation using intrinsic mechanisms is a challenging topic in nanotechnology.Herein,we employ molecular dynamics simulations to investigate the mass transport inside carbon nanotubes(CNT)with temperature gradients,specifically the effects of adding a static carbon hoop to the outside of a CNT on the transport of a nanomotor inside the CNT.We reveal that the underlying mechanism is the uneven potential energy created by the hoops,i.e.,the hoop outside the CNT forms potential energy barriers or wells that affect mass transport inside the CNT.This fundamental control of directional mass transportation may lead to promising routes for nanoscale actuation and energy conversion.展开更多
The stability of cemented backfill mass is important to keep miners and equipment safe in underground backfill miming.The stress-strain behavior, resistivity and thermal infrared(TIR) characteristics of backfill mass ...The stability of cemented backfill mass is important to keep miners and equipment safe in underground backfill miming.The stress-strain behavior, resistivity and thermal infrared(TIR) characteristics of backfill mass under uniaxial compression were investigated. The monitoring system consisted of a TIR observation system, a stress-strain monitoring system and a resistivity measurement system. Precursory information for impending failure of cemented backfill mass was collected, including TIR, strain and resistivity precursors. The sensitivity and difference of different monitoring information to the same failure event were compared.The results show that the time-space evolution process of the resistivity and TIR is basically the same as the whole process from compression deformation to failure of backfill mass, and the time variation of resistivity and TIR is obviously characterized by stage.The resistivity precursor turns out earlier than the TIR and the strain. The resistivity relation with loading compression is anti-symmetry, decreasing as the compression stress increases before the peak strength of backfill mass. However, when the backfill mass enters into the phase of failure, the resistivity starts to increase as the stress increases. The change of the resistivity growth direction can be regarded as the resistivity-caution-point for the failure of backfill mass under uniaxial compression. It is also indicated that the TIR information mainly represents the surface temperature evolution in the process of compression before the backfill enters into the plastic-yield state. It can be a valuable tool to obtain the precursors for failure of cemented backfill mass for backfill mines.展开更多
Natural ventilation is driven by either buoyancy forces or wind pressure forces or their combinations that inherit stochastic variation into ventilation rates. Since the ventilation rate is a nonlinear function of mul...Natural ventilation is driven by either buoyancy forces or wind pressure forces or their combinations that inherit stochastic variation into ventilation rates. Since the ventilation rate is a nonlinear function of multiple variable factors including wind speed, wind direction, internal heat source and building structural thermal mass, the conventional methods for quantifying ventilation rate simply using dominant wind direction and average wind speed may not accurately describe the characteristic performance of natural ventilation. From a new point of view, the natural ventilation performance of a single room building under fluctuating wind speed condition using the Monte-Carlo simulation approach was investigated by incorporating building facade thermal mass effect. Given a same hourly turbulence intensity distribution, the wind speeds with 1 rain frequency fluctuations were generated using a stochastic model, the modified GARCH model. Comparisons of natural ventilation profiles, effective ventilation rates, and air conditioning electricity use for a three-month period show statistically significant differences (for 80% confidence interval) between the new calculations and the traditional methods based on hourly average wind speed.展开更多
On the basis of the analysis of field thermogeochemical data along abnormal zones of a thermal stream in the Bukhara-Khiva, oil-and-gas region of the Turan (Tegermen, Chagakul, Shimoly Alat, Beshtepa) was succeeded to...On the basis of the analysis of field thermogeochemical data along abnormal zones of a thermal stream in the Bukhara-Khiva, oil-and-gas region of the Turan (Tegermen, Chagakul, Shimoly Alat, Beshtepa) was succeeded to obtain important data on a deep structure of sites. Data of gas-chemical and geothermal observations show about confinedness of abnormal concentration of methane to zones of the increased values of the temperature field the measured values of temperatures (Tegermen Square and others). On geoelectric section mines 2-D of inversion of the MT-field depth of 4000 m are lower, among very high-resistance the chemogenic and carbonate deposits of the Paleozoic is traced the subvertical carrying-out abnormal zone. This zone is identified as the channel of a deep heat and mass transfer with which hydrocarbon (HC) deposits are connected. It is shown that electro-investigation when using a geophysical complex can and has to become “advancing” at exploration by oil and gas.展开更多
The objective of present work is to study the thermo diffusion effect on an unsteady simultaneous convective heat and mass transfer flow of an incompressible, electrically conducting, heat generating/absorbing fluid a...The objective of present work is to study the thermo diffusion effect on an unsteady simultaneous convective heat and mass transfer flow of an incompressible, electrically conducting, heat generating/absorbing fluid along a semi-infinite moving porous plate embedded in a porous medium with the presence of pressure gradient, thermal radiation field and chemical reaction. It is assumed that the permeable plate is embedded in a uniform porous medium and moves with a constant velocity in the flow direction in the presence of a transverse magnetic field. It is also assumed that the free stream consists of a mean velocity, temperature and concentration over which are super imposed an exponentially varying with time. The equations of continuity, momentum, energy and diffusion, which govern the flow field, are solved by using a regular perturbation method. The behavior of the velocity, temperature, concentration, Skin-friction, rate of heat transfer and rate of mass transfer has been discussed for variations in the physical parameters. An increase in both Pr and R results a decrease in thermal boundary layer thickness. However, concentration decreases as Kr, Sc increase but it increases with an increase in both So and δ.展开更多
The primary objective of present investigation is to introduce the novel aspects of convective mass condition and thermal radiation in the peristaltic transport of fluid. Magnetohydrodynamic(MHD) fluid was considered ...The primary objective of present investigation is to introduce the novel aspects of convective mass condition and thermal radiation in the peristaltic transport of fluid. Magnetohydrodynamic(MHD) fluid was considered in a symmetric channel. Heat and mass transfer characteristics were analyzed in the presence of Soret and Dufour effects, and the results were presented via two forms of thermal radiation. The temperature, concentration and pressure rise per wavelength were examined. It is observed that the velocity slip and magnetic field parameters have opposite effects on the pressure rise per wavelength. Temperature of fluid is a decreasing function of the radiation parameter. Further, the temperature of fluid decreases by increasing the heat transfer Biot number. It is notified that the heat transfer rate at the wall is a decreasing function of radiation parameter.展开更多
Thermal mass is currently evaluated with "admittance" which is the ability of the element to exchange heat with the environment and is based on specific heat capacity, thermal conductivity and density. The aim of th...Thermal mass is currently evaluated with "admittance" which is the ability of the element to exchange heat with the environment and is based on specific heat capacity, thermal conductivity and density. The aim of this study is to evaluate the effect of thermal properties namely, density, specific heat capacity and thermal conductivity on thermal mass. The objective of the study is to carry out laboratory experiments by measuring such thermal properties of concrete mixes with various percentages of GGBS (ground granulated blast furnace slag), PFA (pulverized fuel ash), and SF (silica fume) and RCA (recycled coarse aggregates). The results obtained from these tests would contribute to the evaluation of how such thermal properties influence the thermal admittance and hence the thermal mass performance of sustainable concrete elements in a building system.展开更多
Three seabed-mounted TD/CTD chains and two upward-looking acoustic Doppler current profilers (ADCPs) in the southwest of Zhangzi Island are used and a simultaneous cruise observation in the northern North Yellow Sea (...Three seabed-mounted TD/CTD chains and two upward-looking acoustic Doppler current profilers (ADCPs) in the southwest of Zhangzi Island are used and a simultaneous cruise observation in the northern North Yellow Sea (NYS) is conducted to study temperature variation in the bottom thermal front zone of the NYS Cold Water Mass (NYSCWM) during the summer of 2009. In the flood-ebb tidal cycles, the bottom temperature decreases (increases) during flood (ebb) tides, which are dominated by the tidal-current induced horizontal advection. The ebb tide-induced temperature increase is larger than the flood tide-induced tempera- ture decrease due to seasonal warming. In the spring-neap tidal cycles, the temperature and the vertical temperature structure show notable fortnightly variation from 16 July to 25 August. The bottom temperature increases from neap to spring tides and decreases from spring to neap. The Richardson number demonstrates strengthened vertical mixing during spring tides but enhanced stratifica- tion during neap tides. The spring-neap variation in vertical shear caused by tidal current is the dominant factor that induces the fort- nightly variation in vertical mixing and thus bottom temperature.展开更多
Thermally induced apoptosis for tumors depends mainly on the intrinsic characteristics of biological tissues as well as treatment temperature profile during magnetic hyperthermia.Further,treatment temperature distribu...Thermally induced apoptosis for tumors depends mainly on the intrinsic characteristics of biological tissues as well as treatment temperature profile during magnetic hyperthermia.Further,treatment temperature distribution inside tumor depends on the injection behavior of irregular tumors,such as the injection dose and the injection location of nanofluids.In order to improve the treatment effect,the simulated annealing algorithm is adopted in this work to optimize the nanofluid injection behavior,and the improved Arrhenius model is used to evaluate the malignant ablations for three typical malignant tumor cell models.In addition,both the injection behavior optimization and the mass diffusion of nanofluid are both taken into consideration in order to improve the treatment effect.The simulation results demonstrate that the injection behavior can be optimized effectively by the proposed optimization method before therapy,the result of which can also conduce to improving the thermal apoptosis possibility for proposed typical malignant cells.Furthermore,an effective approach is also employed by considering longer diffusion duration and correct power dissipation at the same time.The results show that a better result can then be obtained than those in other cases when the power dissipation of MNPs is set to be QMNP=5.4×10^(7)W·m^(3) and the diffusion time is 16 h.展开更多
Taking advantage of heat absorbing and releasing capability of phase change material(PCM),Paraffin wax-based concrete was prepared to assess its automatic temperature control performance.The mechanical properties of P...Taking advantage of heat absorbing and releasing capability of phase change material(PCM),Paraffin wax-based concrete was prepared to assess its automatic temperature control performance.The mechanical properties of PCM concrete with eight different Paraffin wax contents were tested by the cube compression test and four-point bending test.The more Paraffin wax incorporated,the greater loss of the compressive strength and bending strength.Based on the mechanical results,four contents of Paraffin wax were chosen for studying PCM concrete's thermal properties,including thermal conductivity,thermal diffusivity,specific heat capacity,thermal expansion coefficient and adiabatic temperature rise.When the Paraffin wax content increases from 10%to 20%,the thermal conductivity and the thermal diffusivity decrease from 7.31 kJ/(m·h·°C)to 7.10 kJ/(m·h·°C)and from 3.03×10−3 m2/h to 2.44×10−3 m2/h,respectively.Meanwhile the specific heat capacity and thermal expansion coefficient rise from 5.38×10−1 kJ/(kg·°C)to 5.76×10−1 kJ/(kg·°C)and from 9.63×10−6/°C to 14.02×10−6/°C,respectively.The adiabatic temperature rise is found to decrease with an increasing Paraffin wax content.Considering both the mechanical and thermal properties,15%of Paraffin wax was elected for the mass concrete model test,and the model test results confirm the effect of Paraffin wax in automatic mass concrete temperature control.展开更多
Non-thermal C/H/Ar plasmas are widely applied to carbonaceous material production and processing.In this work,plasma parameters and gaseous species of the atmospheric non-thermal C/H/Ar plasmas produced by an atmosphe...Non-thermal C/H/Ar plasmas are widely applied to carbonaceous material production and processing.In this work,plasma parameters and gaseous species of the atmospheric non-thermal C/H/Ar plasmas produced by an atmospheric-pressure DC arc discharge generator in CH_4/Ar were investigated.The voltage-current characteristics were measured for different CH_4/Ar ratios.Optical emission spectroscopy was employed to analyze the electron excitation temperature,gas temperature and electron density under various discharge conditions.The hydrocarbon molecules produced in the CH4/Ar plasmas were detected with photoionization mass spectrometry.The optical spectral results demonstrated that the electron excitation temperature was 0.4-1 eV,the gas temperature was 2800-4200 K and the electron density was in the range of(5-20)×10^15 cm^-3.The mass spectrum indicated that a variety of unsaturated hydrocarbons(C2H4,C3H6,C6H6,etc.) and several highly unsaturated hydrocarbons(C4H2,C5H6,etc.) were produced in the non-thermal arc plasmas.展开更多
The effect of temperature on the functional groups transition of N-methyl-N-nitroso-p-toluenesulfonamide (Diazald) and thermal decomposition were investigated by Fourier Transform Infrared Spectroscopy (FT-IR) and...The effect of temperature on the functional groups transition of N-methyl-N-nitroso-p-toluenesulfonamide (Diazald) and thermal decomposition were investigated by Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimeter (DSC). The results showed that the functional groups transition of Diazald was temperature dependent, and thermal decomposition of Diazald was accelerated above 47.7℃. The HPLC-ESI-MS method was used for Diazald analysis, which indicated the strong hydrogen bonding between Diazald and water and instability of the NO group.展开更多
The day/night (diurnal) changes in temperature and solar radiation pose challenges for maintaining human thermal comfort in buildings. Passive and energy-conserving buildings seek to manage the available thermal ene...The day/night (diurnal) changes in temperature and solar radiation pose challenges for maintaining human thermal comfort in buildings. Passive and energy-conserving buildings seek to manage the available thermal energy by lowering peaks and dampening the fluctuations in order to maintain conditions for human comfort. Appropriate use of thermal mass moderates the internal temperatures by averaging diurnal extremes. Thermal mass is one of the powerful tools which architects and designers can use to control temperature. It can be used to optimize the performance of energy-conserving buildings that rely primarily on mechanical heating and cooling strategies. Massive building envelopes-such as masonry, concrete, earth, and insulating concrete forms (ICFs) can be utilized as one of the simplest ways of reducing building heating and cooling loads. This article analyses the role and effectiveness of thermal mass as a strategy for providing indoor thermal comfort for passive solar and energy conserving buildings.展开更多
Mass measurement is an essential analytical tool in the characterization of materials.Here we present a method for measuring the mass of an individual nanoparticle which has a fg-level mass.This method enables a tempe...Mass measurement is an essential analytical tool in the characterization of materials.Here we present a method for measuring the mass of an individual nanoparticle which has a fg-level mass.This method enables a temperatureindependent mass measurement with the assistance of a sinusoidal electrostatic driving force.With this approach,we successfully track the change in properties of an optically levitated nanoparticle,such as mass,temperature,and electric charge,with air pressure.An abrupt change in the mass of silica nanoparticles is found to violate the Zhuravlev model.This method can be utilized to extend the mass analysis of materials,such as thermogravimetric analysis,to individual microor nano-particles.展开更多
Global change has become a hot spot in Quaternary geology, and high\|precision, high\|sensitivity dating is also an urgent problem which needs to be solved. This paper presents some achievements in U\|series dating of...Global change has become a hot spot in Quaternary geology, and high\|precision, high\|sensitivity dating is also an urgent problem which needs to be solved. This paper presents some achievements in U\|series dating of marine corals by thermal ionization mass spectrometry (TIMS) and its application to the study of paleo\|environments. Recently, coral samples were determined for their ages on a MAT\|262 mass spectrometer and satisfactory results have been obtained.展开更多
The finite element software,MIDAS is used to predict the distribution of temperatures and,analyzes the cracking control methods within a hydrating mass concrete.The temperature control of mass concrete has great signi...The finite element software,MIDAS is used to predict the distribution of temperatures and,analyzes the cracking control methods within a hydrating mass concrete.The temperature control of mass concrete has great significance in assuring the project quality.Adiabatic or semi adiabatic temperature measurement is mostly used for measuring and controlling the temperature fluctuation during construction.The temperature distribution produced by the finite element thermal analysis of the model is used to quantify the maximum allowable internal temperature difference before crack initiation on concrete.This study analyzes the data from one high-rise structure project in Shanghai are used to verify the finite element model developed.Results suggest that reliance on a limiting maximum temperature differential to control cracking in massive concrete applications should be supplemented with a requirement for analysis showing the calculated spatial temperature and stress response to the predicted temperature distribution within the concrete,to ensure that the induced tensile stresses will not exceed the tensile strength of the concrete and so minimize the risk of having thermal cracks at early age.展开更多
基金Project supported by the Doctoral Fund of Yanshan University (Grant No.B919)the Program of Independent Research for Young Teachers of Yanshan University (Grant No.020000534)the S&T Program of Hebei Province of China (Grant No.QN2016123)。
文摘Controlling mass transportation using intrinsic mechanisms is a challenging topic in nanotechnology.Herein,we employ molecular dynamics simulations to investigate the mass transport inside carbon nanotubes(CNT)with temperature gradients,specifically the effects of adding a static carbon hoop to the outside of a CNT on the transport of a nanomotor inside the CNT.We reveal that the underlying mechanism is the uneven potential energy created by the hoops,i.e.,the hoop outside the CNT forms potential energy barriers or wells that affect mass transport inside the CNT.This fundamental control of directional mass transportation may lead to promising routes for nanoscale actuation and energy conversion.
基金Projects(51504256,51004109)supported by the National Natural Science Foundation of ChinaProject(zdsys006)supported by State Key Laboratory of Safety and Health for Metal Mines,ChinaProject(2013BAB02B04)supported by the National Science and Technology Support Plan,China
文摘The stability of cemented backfill mass is important to keep miners and equipment safe in underground backfill miming.The stress-strain behavior, resistivity and thermal infrared(TIR) characteristics of backfill mass under uniaxial compression were investigated. The monitoring system consisted of a TIR observation system, a stress-strain monitoring system and a resistivity measurement system. Precursory information for impending failure of cemented backfill mass was collected, including TIR, strain and resistivity precursors. The sensitivity and difference of different monitoring information to the same failure event were compared.The results show that the time-space evolution process of the resistivity and TIR is basically the same as the whole process from compression deformation to failure of backfill mass, and the time variation of resistivity and TIR is obviously characterized by stage.The resistivity precursor turns out earlier than the TIR and the strain. The resistivity relation with loading compression is anti-symmetry, decreasing as the compression stress increases before the peak strength of backfill mass. However, when the backfill mass enters into the phase of failure, the resistivity starts to increase as the stress increases. The change of the resistivity growth direction can be regarded as the resistivity-caution-point for the failure of backfill mass under uniaxial compression. It is also indicated that the TIR information mainly represents the surface temperature evolution in the process of compression before the backfill enters into the plastic-yield state. It can be a valuable tool to obtain the precursors for failure of cemented backfill mass for backfill mines.
文摘Natural ventilation is driven by either buoyancy forces or wind pressure forces or their combinations that inherit stochastic variation into ventilation rates. Since the ventilation rate is a nonlinear function of multiple variable factors including wind speed, wind direction, internal heat source and building structural thermal mass, the conventional methods for quantifying ventilation rate simply using dominant wind direction and average wind speed may not accurately describe the characteristic performance of natural ventilation. From a new point of view, the natural ventilation performance of a single room building under fluctuating wind speed condition using the Monte-Carlo simulation approach was investigated by incorporating building facade thermal mass effect. Given a same hourly turbulence intensity distribution, the wind speeds with 1 rain frequency fluctuations were generated using a stochastic model, the modified GARCH model. Comparisons of natural ventilation profiles, effective ventilation rates, and air conditioning electricity use for a three-month period show statistically significant differences (for 80% confidence interval) between the new calculations and the traditional methods based on hourly average wind speed.
文摘On the basis of the analysis of field thermogeochemical data along abnormal zones of a thermal stream in the Bukhara-Khiva, oil-and-gas region of the Turan (Tegermen, Chagakul, Shimoly Alat, Beshtepa) was succeeded to obtain important data on a deep structure of sites. Data of gas-chemical and geothermal observations show about confinedness of abnormal concentration of methane to zones of the increased values of the temperature field the measured values of temperatures (Tegermen Square and others). On geoelectric section mines 2-D of inversion of the MT-field depth of 4000 m are lower, among very high-resistance the chemogenic and carbonate deposits of the Paleozoic is traced the subvertical carrying-out abnormal zone. This zone is identified as the channel of a deep heat and mass transfer with which hydrocarbon (HC) deposits are connected. It is shown that electro-investigation when using a geophysical complex can and has to become “advancing” at exploration by oil and gas.
文摘The objective of present work is to study the thermo diffusion effect on an unsteady simultaneous convective heat and mass transfer flow of an incompressible, electrically conducting, heat generating/absorbing fluid along a semi-infinite moving porous plate embedded in a porous medium with the presence of pressure gradient, thermal radiation field and chemical reaction. It is assumed that the permeable plate is embedded in a uniform porous medium and moves with a constant velocity in the flow direction in the presence of a transverse magnetic field. It is also assumed that the free stream consists of a mean velocity, temperature and concentration over which are super imposed an exponentially varying with time. The equations of continuity, momentum, energy and diffusion, which govern the flow field, are solved by using a regular perturbation method. The behavior of the velocity, temperature, concentration, Skin-friction, rate of heat transfer and rate of mass transfer has been discussed for variations in the physical parameters. An increase in both Pr and R results a decrease in thermal boundary layer thickness. However, concentration decreases as Kr, Sc increase but it increases with an increase in both So and δ.
文摘The primary objective of present investigation is to introduce the novel aspects of convective mass condition and thermal radiation in the peristaltic transport of fluid. Magnetohydrodynamic(MHD) fluid was considered in a symmetric channel. Heat and mass transfer characteristics were analyzed in the presence of Soret and Dufour effects, and the results were presented via two forms of thermal radiation. The temperature, concentration and pressure rise per wavelength were examined. It is observed that the velocity slip and magnetic field parameters have opposite effects on the pressure rise per wavelength. Temperature of fluid is a decreasing function of the radiation parameter. Further, the temperature of fluid decreases by increasing the heat transfer Biot number. It is notified that the heat transfer rate at the wall is a decreasing function of radiation parameter.
文摘Thermal mass is currently evaluated with "admittance" which is the ability of the element to exchange heat with the environment and is based on specific heat capacity, thermal conductivity and density. The aim of this study is to evaluate the effect of thermal properties namely, density, specific heat capacity and thermal conductivity on thermal mass. The objective of the study is to carry out laboratory experiments by measuring such thermal properties of concrete mixes with various percentages of GGBS (ground granulated blast furnace slag), PFA (pulverized fuel ash), and SF (silica fume) and RCA (recycled coarse aggregates). The results obtained from these tests would contribute to the evaluation of how such thermal properties influence the thermal admittance and hence the thermal mass performance of sustainable concrete elements in a building system.
基金supported by the National Natural Science Foundation of China (Nos. U1706215, 41506012, 41430963 and 41606005)
文摘Three seabed-mounted TD/CTD chains and two upward-looking acoustic Doppler current profilers (ADCPs) in the southwest of Zhangzi Island are used and a simultaneous cruise observation in the northern North Yellow Sea (NYS) is conducted to study temperature variation in the bottom thermal front zone of the NYS Cold Water Mass (NYSCWM) during the summer of 2009. In the flood-ebb tidal cycles, the bottom temperature decreases (increases) during flood (ebb) tides, which are dominated by the tidal-current induced horizontal advection. The ebb tide-induced temperature increase is larger than the flood tide-induced tempera- ture decrease due to seasonal warming. In the spring-neap tidal cycles, the temperature and the vertical temperature structure show notable fortnightly variation from 16 July to 25 August. The bottom temperature increases from neap to spring tides and decreases from spring to neap. The Richardson number demonstrates strengthened vertical mixing during spring tides but enhanced stratifica- tion during neap tides. The spring-neap variation in vertical shear caused by tidal current is the dominant factor that induces the fort- nightly variation in vertical mixing and thus bottom temperature.
基金Project supported by the National Natural Science Foundation of China (Grant No. 62071124)the Natural Science Foundation of Fujian Province, China (Grant No. 2020J01464)+2 种基金the Fund from the Education Department of Fujian Province, China (Grant No. JAT190013)the Fund from the Fuzhou University, China (Grant No. GXRC-19044)the Conselho Nacional de Desenvolvimento Científico e Tecnológico (BR) (CNPq) (Grant No. 309244/2018-8)
文摘Thermally induced apoptosis for tumors depends mainly on the intrinsic characteristics of biological tissues as well as treatment temperature profile during magnetic hyperthermia.Further,treatment temperature distribution inside tumor depends on the injection behavior of irregular tumors,such as the injection dose and the injection location of nanofluids.In order to improve the treatment effect,the simulated annealing algorithm is adopted in this work to optimize the nanofluid injection behavior,and the improved Arrhenius model is used to evaluate the malignant ablations for three typical malignant tumor cell models.In addition,both the injection behavior optimization and the mass diffusion of nanofluid are both taken into consideration in order to improve the treatment effect.The simulation results demonstrate that the injection behavior can be optimized effectively by the proposed optimization method before therapy,the result of which can also conduce to improving the thermal apoptosis possibility for proposed typical malignant cells.Furthermore,an effective approach is also employed by considering longer diffusion duration and correct power dissipation at the same time.The results show that a better result can then be obtained than those in other cases when the power dissipation of MNPs is set to be QMNP=5.4×10^(7)W·m^(3) and the diffusion time is 16 h.
基金This work is jointly supported by the National Natural Science Foundation of China(Grant Nos.51909223,51902270)the National Science Fund for Distinguished Young Scholars(Grant No.41825015)+2 种基金the Natural Science Basic Research Program of Shaanxi(Grant No.2019JQ-921)the Special research project of the Education Department of Shaanxi Provincial Government(Grant No.19JK0913)the Special Fund for the Launch of Scientific Research in Xijing University(Grant No.XJ18T02).
文摘Taking advantage of heat absorbing and releasing capability of phase change material(PCM),Paraffin wax-based concrete was prepared to assess its automatic temperature control performance.The mechanical properties of PCM concrete with eight different Paraffin wax contents were tested by the cube compression test and four-point bending test.The more Paraffin wax incorporated,the greater loss of the compressive strength and bending strength.Based on the mechanical results,four contents of Paraffin wax were chosen for studying PCM concrete's thermal properties,including thermal conductivity,thermal diffusivity,specific heat capacity,thermal expansion coefficient and adiabatic temperature rise.When the Paraffin wax content increases from 10%to 20%,the thermal conductivity and the thermal diffusivity decrease from 7.31 kJ/(m·h·°C)to 7.10 kJ/(m·h·°C)and from 3.03×10−3 m2/h to 2.44×10−3 m2/h,respectively.Meanwhile the specific heat capacity and thermal expansion coefficient rise from 5.38×10−1 kJ/(kg·°C)to 5.76×10−1 kJ/(kg·°C)and from 9.63×10−6/°C to 14.02×10−6/°C,respectively.The adiabatic temperature rise is found to decrease with an increasing Paraffin wax content.Considering both the mechanical and thermal properties,15%of Paraffin wax was elected for the mass concrete model test,and the model test results confirm the effect of Paraffin wax in automatic mass concrete temperature control.
基金supported by National Natural Science Foundation of China(Nos.11035005,11475174,50876101)USTC-NSRL Association Funding(No.KY2090130001)
文摘Non-thermal C/H/Ar plasmas are widely applied to carbonaceous material production and processing.In this work,plasma parameters and gaseous species of the atmospheric non-thermal C/H/Ar plasmas produced by an atmospheric-pressure DC arc discharge generator in CH_4/Ar were investigated.The voltage-current characteristics were measured for different CH_4/Ar ratios.Optical emission spectroscopy was employed to analyze the electron excitation temperature,gas temperature and electron density under various discharge conditions.The hydrocarbon molecules produced in the CH4/Ar plasmas were detected with photoionization mass spectrometry.The optical spectral results demonstrated that the electron excitation temperature was 0.4-1 eV,the gas temperature was 2800-4200 K and the electron density was in the range of(5-20)×10^15 cm^-3.The mass spectrum indicated that a variety of unsaturated hydrocarbons(C2H4,C3H6,C6H6,etc.) and several highly unsaturated hydrocarbons(C4H2,C5H6,etc.) were produced in the non-thermal arc plasmas.
文摘The effect of temperature on the functional groups transition of N-methyl-N-nitroso-p-toluenesulfonamide (Diazald) and thermal decomposition were investigated by Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimeter (DSC). The results showed that the functional groups transition of Diazald was temperature dependent, and thermal decomposition of Diazald was accelerated above 47.7℃. The HPLC-ESI-MS method was used for Diazald analysis, which indicated the strong hydrogen bonding between Diazald and water and instability of the NO group.
文摘The day/night (diurnal) changes in temperature and solar radiation pose challenges for maintaining human thermal comfort in buildings. Passive and energy-conserving buildings seek to manage the available thermal energy by lowering peaks and dampening the fluctuations in order to maintain conditions for human comfort. Appropriate use of thermal mass moderates the internal temperatures by averaging diurnal extremes. Thermal mass is one of the powerful tools which architects and designers can use to control temperature. It can be used to optimize the performance of energy-conserving buildings that rely primarily on mechanical heating and cooling strategies. Massive building envelopes-such as masonry, concrete, earth, and insulating concrete forms (ICFs) can be utilized as one of the simplest ways of reducing building heating and cooling loads. This article analyses the role and effectiveness of thermal mass as a strategy for providing indoor thermal comfort for passive solar and energy conserving buildings.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12104438 and 62225506)CAS Project for Young Scientists in Basic Research(Grant No.YSBR-049)the Fundamental Research Funds for the Central Universities.
文摘Mass measurement is an essential analytical tool in the characterization of materials.Here we present a method for measuring the mass of an individual nanoparticle which has a fg-level mass.This method enables a temperatureindependent mass measurement with the assistance of a sinusoidal electrostatic driving force.With this approach,we successfully track the change in properties of an optically levitated nanoparticle,such as mass,temperature,and electric charge,with air pressure.An abrupt change in the mass of silica nanoparticles is found to violate the Zhuravlev model.This method can be utilized to extend the mass analysis of materials,such as thermogravimetric analysis,to individual microor nano-particles.
文摘Global change has become a hot spot in Quaternary geology, and high\|precision, high\|sensitivity dating is also an urgent problem which needs to be solved. This paper presents some achievements in U\|series dating of marine corals by thermal ionization mass spectrometry (TIMS) and its application to the study of paleo\|environments. Recently, coral samples were determined for their ages on a MAT\|262 mass spectrometer and satisfactory results have been obtained.
文摘The finite element software,MIDAS is used to predict the distribution of temperatures and,analyzes the cracking control methods within a hydrating mass concrete.The temperature control of mass concrete has great significance in assuring the project quality.Adiabatic or semi adiabatic temperature measurement is mostly used for measuring and controlling the temperature fluctuation during construction.The temperature distribution produced by the finite element thermal analysis of the model is used to quantify the maximum allowable internal temperature difference before crack initiation on concrete.This study analyzes the data from one high-rise structure project in Shanghai are used to verify the finite element model developed.Results suggest that reliance on a limiting maximum temperature differential to control cracking in massive concrete applications should be supplemented with a requirement for analysis showing the calculated spatial temperature and stress response to the predicted temperature distribution within the concrete,to ensure that the induced tensile stresses will not exceed the tensile strength of the concrete and so minimize the risk of having thermal cracks at early age.