Characteristics Of Temperature Field Research Articles

Characteristic Analysis of Rural Environment Temperature Field

Taking villages in the northern plain of Shaoxing County Zhejiang Province as the research object and by using heat transfer model and remote sensing image analysis method and taking advantage of surface temperature information varying in different areas recorded by ETM thermal infrared band and through selection of special endmember, we realize the separation of background and ambient superposed brightness temperature and establish statistical model on change of superimposed environmental brightness temperature based on distance and analyze characteristics of rural environment temperature field according to the features of heat exchange type. Study shows that endmember brightness temperatures of different surface features in the study area are respectively as follows: hard surface is 304.663K, water body is 297.851K, grassland is 298.966K, woodland is 298.827K; superimposed environmental temperature in village area is about 1.737K. Environment superposed brightness temperature and distance function are tools to describe the temperature field, predicting pixel brightness temperature by using the heat transfer model is more accurate than using linear spectrum mixed model.

Terrestrial Heat Flow in the Qagan Sag, Inner Mongolia

AbstractThe Qagan sag has the largest oil and gas exploration potential in the Inggen‐Ejin Qi basin, Inner Mongolia. The terrestrial heat flow research is still blank in the Qagan sag and rest of the Inggen‐Ejin Qi basin, which seriously restricts the oil and gas resource assessment in the basin. In this work, 107 rock thermal conductivity data of 19 wells were measured and in‐situ corrected, and the rock thermal conductivities of each stratum were obtained by the union average formula. Based on the 9 wells' temperatures, combined with the above rock thermal conductivity data, the geothermal gradients and terrestrial heat flow were calculated. The results show the Qagan sag has the characteristics of the medium temperature field between tectonically stable and active regions, with an average thermal gradient of 33.6 °C/km and an average terrestrial heat flow value of 74.5 mW/m2. This work provides the geothermal data for oil and gas resource assessment of the Qagan sag and other sags of the Inggen‐Ejin Qi basin.

Heat Damage of High-Temperature Rock Tunnel by Weighted Residual Method in Tibet Plateau

According to the weighted residual method to deduce the finite element method of temperature field. The Jiwoxiga high-temperature rock tunnel on the Lhasa-Shigatse railway line is taked for example in the paper, then the actual drilling temperature data was combined to establish three-dimensional finite element model, the basic characteristics of temperature field was forecasted, the basic rule of temperature was obtained and the data can be compared with the actual data. It can provide references for the actual construction and ensure the similar engineering construction.

Influence of the Scheduling of the Three Gorges Reservoir on the Hydrodynamic Field in Xiangxi River

The characteristics of water temperature and hydrodynamic field in Xiangxi Bay of Three Gorges Reservoir are studied by numerical simulation method. The result shows that the lifting of water level wakened the density current intensity and the vertical mixing of water, and increased the temperature difference between the surface and bottom water. Simultaneously, the dropping of water level enhanced the density current intensity and the vertical mixing of water, and decreased the temperature difference between the surface and bottom water. The numerical modeling is a valid tool in the prediction of the hydrodynamic field in estuary, as a valuable tool in understanding the development and progression of density currents and the influence of scheduling on the hydrodynamic characteristics in the Xiangxi Bay of the Three Gorges Reservoir, therefore, this work could provide helpful supports for nutrient transportation and ecological environmental evaluation.

Cloud water content effects on computing spectral characteristics of temperature fields and turbulent heat fluxes in the cumulus cloud zones as derived from airborne observations

Analyzed are the earlier obtained data on the dynamic structure of cumulus (convective) clouds in order to estimate cloud water content effects on the air temperature, computed turbulent fluxes, and their spectral characteristics. It is demonstrated that the cloud and precipitation droplets falling to the aircraft temperature sensor provoke an error in temperature measurements. Developed is a method for taking into account these effects and for computing the correct air temperature fluctuations in the cloud, wavelet spectra of the temperature, and wavelet cospectra of heat fluxes. The use of the method enabled to construct a consistent picture of horizontal heat flux distribution in the cumulus zone depending on the wave number and cloud location. It is shown that mesoscale eddies with the scale of more than 500 m are the main factors of heat exchange between clouds and the ambient space, and the role of turbulence consists only in the mixing inside the cloud. The conclusion is made that the temperature adjustment to the water content of the cloud is needed for correct interpretation of the results of aircraft observations of dynamic structure of cumulus clouds.

Numerical Study of Multi-Fuel Jet Inverse Diffusion Flame

A numerical simulation was performed to investigate a multi-jet inverse methane diffusion flame. The numerical simulation was established by the commercial CFD code Fluent for an air jet surrounding by four fuel jets. Using a Pre PDF technique to estimate the interaction between the chemistry and turbulent flow. The simulation results show a better data of the flame temperature field characteristics and the CO, CO2, NO H2O, CH4, O2 concentrations. The influence of the velocity of the fuel and air jet on the NO production is appearing very clear.

Thermal characteristics of induction heating in cold crucible used for directional solidification

Cold crucible can be used to directionally solidify TiAl based alloys because of its low contamination. In this study, TiAlNb, steel and aluminium charges were used to investigate the characteristics of heat transfer and temperature field. Experiments were designed to measure the temperature of the charges in induction heating of cold crucible. A 2-D finite element model was established to calculate the temperature field of the charges in induction heating. The calculated results are in good agreement with the measured values. The results show that the temperature rising in induction heating and the steady temperature are affected by the thermal properties of the charges. It is found that the temperature rising gradually slows down and reaches a steady temperature finally. TiAlNb charge exhibits the highest steady temperature compared with steel and aluminium. The time to reach the steady temperature depends on the material properties, the power and the charge position.

Unsteady numerical simulation of flow and heat transfer in a uniformly Joule-heated rectangular pool

Based on the Joule heating nuclear waste treatment technology, a series of numerical simulation of fluid flow and heat transfer based on two-dimensional non-steady state model has been studied, the fluid is in a rectangular cavity with an aspect ratio of 2, the direct current contributes heat for heating the process medium by a pair of plate electrodes, the top wall is cooled with atmosphere and all the other walls are kept thermally insulated. For Pr=1 fluid, the thermally driven stable convection and the electromagnetically driven stable flow can be observed respectively or both gravitationally and electromagnetically driven stable convection exhibit. The threshold Hartmann number for the first transition from an ax symmetric 2 cells steady flow to a steady non-asymmetric state 1 roll flow is 159.687, where the Nusselt number exhibits a minimum value. And the second transition from non-asymmetric state 1 roll flow to a steady asymmetric 2 rolls flow is fixed at Ha=178.88. It is found that physically realizable periodic oscillation flow evolves for the low Pr fluid (Pr=0.01), which can significantly affect the heat transfer. These transient characteristics of velocity and temperature fields are presented graphically.

FREQUENCY OF ATMOSPHERIC BLOCKING ASSOCIATED WITH MERIDIONAL SURFACE TEMPERATURE CHARACTERISTICS IN BOREAL WINTER IN THE MID-LATITUDES

Atmospheric blocking is one of the main causes of extreme meteorological events such as spells of extremely cold weather, heat wave and continuous heavy rainfall in the mid-latitudes. The European Centre for Medium-Range Weather Forecasts Reanalysis Dataset (ERA-40) was analyzed to clarify both the characteristics of the latitudinal surface temperature field and the frequency of atmospheric blocking (FAB) in December, January, and February between 1960 and 1999. In years with a small meridional surface temperature gradient between the low and high latitudes, the FAB was larger than the average for the 40-year climatology, as well as persisting for longer and having a longitudinally larger spatial scale. A noticeable characteristic of these years was a larger dominant eddy scale length at the 500-hPa level compared to the average for the climatology. The amplitude of the dominant eddy scale length was also enhanced.

典型河谷型城市春季温湿场特征及其生态环境效应

Rapid urbanization has a significant impact on temperature and humidity,the distribution patterns and structure characteristics of temperature field and humidity field profoundly affect the ecosystems energy flow and material cycle,and further result in a series of eco-environmental problems.In recent years,contribution of the urban heat island effect to the global warming has been widely concerned by people.Distribution characteristics and causes of temperature field and humidity field in typical valley-city were researched widely,there are practical significance on urban eco-environmental construction,city planning,urban architecture design,urban energy usage and the health of residents for the typical valley-city.Lanzhou is a typical valley-city in western China;the level of urbanization is higher than average level of China;and urban area increased rapidly in last 50 years;in addition,air pollution is very serious for natural and anthropogenic reasons.So the urban climate effect is unique in Lanzhou.Based on methods of climate mobile observation,fixed-point observation,GIS spatial analysis and remote sensing,distribution pattern and its evolution of temperature and humidity field in a spring day are simulated in the typical valley-city.The results show that distribution pattern of temperature field is more similar in 14:30 and 20:30,high-value areas are mainly located in the train station,the second thermal power station,the Wulipu cross and Panxuan road area.Thermal centers are mainly concentrated in the Xiguan cross to victory hotel in 8:30.Distribution pattern of humidity field is similar in 8:30 and 20:30,and the large area mainly locates in Xujia mountain forest park,Yantan village and Gaotan village with high vegetation coverage.Using the theory of landscape ecology,and combining distribution of thermal field and humidity field with NDVI map,thermal landscape distribution is analyzed and thermal landscape types are divided.Results show formation of urban thermal landscape pattern has a significant relationship with energy consumption,population,building,underlying surface types,and regions while NDVI 0.5 are corresponding to higher value in humidity field and lower value in thermal field,so the reasonable planning of green belt is very important in eco-city or low-carbon city construction.Finally,using the observation data from urban and suburb weather stations,and analyzing variation of urban heat island effect and dry island effect in the past 50 years.Both urban heat island intensity and dry island intensity are gradually increasing in the past 50 years,the linear trend of urban heat island intensity is 0.31℃ per 10 years,and the linear trend of dry island intensity is-2.1% per 10 years,the trends are dramatically enhanced after the 1970s.The urban heat island intensity in the recent 10 years average to 3.6 ℃ and dry island effect intensity is 11%.Urban heat island intensity and dry island intensity were affected obviously by the level of urbanization,scale of urban construction,characteristics of urban underground and human activities.Urban heat island intensity and dry island intensity also can be a measure of the impact of human activities on the urban ecosystem.

FEM simulation and experimental verification of temperature field and phase transformation in deep cryogenic treatment

Combining with the low temperature material properties and the boiling heat transfer coefficient of specimen immersed in the liquid nitrogen, a numerical model based on metallo-thermo-mechanical couple theory was established to reproduce the deep cryogenic treatment (DCT) process of a newly developed cold work die steel Cr8Mo2SiV (SDC99). Moreover, an experimental setup for rapid temperature measurement was designed to validate the simulation results. The investigation suggests that the differences in temperature and cooling rate between the surface and core of specimen are very significant. However, it should be emphasized that the acute temperature and cooling rate changes during DCT are mainly concentrated on the specimen surface region about 1/3 of the sample thickness. Subjected to DCT, the retained austenite of quenched specimen continues to transform to martensite and finally its phase volume fraction reduces to 2.3%. The predicted results are coincident well with the experimental data, which demonstrates that the numerical model employed in this study can accurately capture the variation characteristics of temperature and microstructure fields during DCT and provide a theoretical guidance for making the reasonable DCT procedure.

Research on Flow Field and Temperature Field Characteristics of One Rocket Charge with Complicated Structure by Numerical Method

The paper researches flow field and temperature field characteristics of one rocket charge with complicated structure by numerical method. The charge, in which there exist the conduction, convection and radiation, consists of the metal shell, seven propellant columns and air gaps. For the reasons, to solve temperature field of the charge is to solve a complex heat transfer problem in a complicated calculation region. A mathematical and physical model for the flow and heat transfer process in the charge is established and unstructured meshes are applied to disperse the complicated calculation region. The SIMPLE algorithm is used to solve the partial differential equations, and the calculation results are in good agreement with the experimental data. On basis of the numerical simulation, the flow field and temperature field characteristics of the charge are researched and subsequently some valuable conclusions are gotten.

Research on Characteristics of the Soil Temperature Field around Vertical Double U-Tube Group of the Heat Exchangers

Based on the temperature monitoring for the double U-tube wells with thermal resistance , numerical simulation researching on two-dimensional temperature field and three-dimensional temperature field was carried out for vertical double U-tube group. Under the condition of 6.5m for horizontal spacing of tube well, the Soil temperature around inner tube wells increases 0.4°C in one year, and 0.24°C for the surrounding tube wells. The paper calculates the increasing temperature of the tube wells, 7.95°C for inner tube wells and 4.70°Cfor surrounding tube wells. The soil temperature of tube wells is rising with the running time increasing, however,the temperature rate of the soil around inner tube wells is larger than the surrounding tube wells’.

Hazard Characteristics from Gas Explosion in Underground Constructions

Gas explosion is likely to become a new type of attack aimed at underground spaces by terrorists. In this paper, as an example for methane-air gaseous mixture, distribution characteristics of shock wave, flame, temperature field and toxic gaseous products generated from gas explosion in a long straight laneway were analyzed. Along the increasing axial distance, shock wave overpressure increases in original flammable gas area but decreases beyond the original gas area. Range of flame exceeds the original gas area. Flame accelerates continually in the original gas area but decelerates beyond the original gas area. The temperature attenuates slowly along the increasing distance in the flame area by virtue of flame front, but attenuates quickly along the increasing distance beyond the flame region. High temperature hazard involves farther area beyond the original gas area.

Low-energy high-current electron beam heating of target with second-phase microinclusions

The temperature field generated by microsecond pulsed low-energy high-current electron beam (LEHCEB) in the surface layer of a stainless-steel target containing second-phase (manganese sulfide, MnS) microinclusions has been numerically simulated. The results of calculations show that the temperature is nonuniformly distributed over the target surface. By the end of the LEHCEB pulse, the temperature in the regions of MnS inclusions significantly exceeds that of the steel matrix. This nonuniformity is related to (i) markedly greater thermal conductivity of steel compared to that of MnS and (ii) the pulsed character of the electron-beam-induced heating of the target surface. It is also established that LEHCEB-induced melting begins at the inclusion-steel interface and then involves the inclusion and spreads over the entire irradiated surface. The dependence of the characteristics of the irradiation-induced temperature field on the parameters of the pulsed electron beam has been studied.

An Objective Algorithm for Detecting and Tracking Tropical Cloud Clusters: Implications for Tropical Cyclogenesis Prediction

Abstract An algorithm to detect and track global tropical cloud clusters (TCCs) is presented. TCCs are organized large areas of convection that form over warm tropical waters. TCCs are important because they are the “seedlings” that can evolve into tropical cyclones. A TCC satisfies the necessary condition of a “preexisting disturbance,” which provides the required latent heat release to drive the development of tropical cyclone circulations. The operational prediction of tropical cyclogenesis is poor because of weaknesses in the observational network and numerical models; thus, past studies have focused on identifying differences between “developing” (evolving into a tropical cyclone) and “nondeveloping” (failing to do so) TCCs in the global analysis fields to produce statistical forecasts of these events. The algorithm presented here has been used to create a global dataset of all TCCs that formed from 1980 to 2008. Capitalizing on a global, Gridded Satellite (GridSat) infrared (IR) dataset, areas of persistent, intense convection are identified by analyzing characteristics of the IR brightness temperature (Tb) fields. Identified TCCs are tracked as they move around their ocean basin (or cross into others); variables such as TCC size, location, convective intensity, cloud-top height, development status (i.e., developing or nondeveloping), and a movement vector are recorded in Network Common Data Form (NetCDF). The algorithm can be adapted to near-real-time tracking of TCCs, which could be of great benefit to the tropical cyclone forecast community.

Model Test Study on Insulator of Cold-Region Tunnel in Northeast China: A Case Study of Gaoling Tunnel

Based on similarity theory, the systemic analysis for the distribution characteristics of tunnel temperature field in two different working conditions of having no thermal insulation and installing PU as insulator is progressed by using manufactured model test platform in order to realize the tunnel temperature field rule in cold regions with or without thermal insulation and the influence of thermal insulation layout pattern on insulating effect. The results show that the temperature variation conforms to the “tunnel freeze-thaw circle” theory without thermal insulation, and the surrounding rock maintains negative temperature all the time in the low temperature environment; the internal temperature field of surrounding rock plays a decisive role on the surface temperature of surrounding rock, which keeps above 0°C after the layout of thermal insulation with appropriate material and thickness.

A Study on Temperature Distribution of Surrounding Rock and Mechanical Characteristics of Lining of Monglian Tunnel under High Geothermal

To solve design and construction problems of Monglian tunnel under high geothermal, based on the change rules of thermal parameters of surrounding rock and lining during excavation period, this paper analyzed the temperature distribution, heat transfer in tunnel and interaction between lining and surrounding rock, then by using numerical simulation, the relationship between temperature field and mechanical characteristics of lining and surrounding rock was discussed. Finally, the methods of using blast furnace cement, utilizing wet spraying concrete construction technology, and making surrounding rock exposure time as short as possible to reduce damages high temperature caused was proposed. The result can provide experience in similar tunnel design and construction.

Inversion and Feedback Research on the Temperature Control and Crack Prevention for Concrete Crane Beam on Rock Wall

Concrete crane beam on a rock wall on a new structure used in underground building has become more common in recent year. But the concrete beam cracking problem always perplexes scientists and engineers. In order to solve this, the construction information inversion and feedback analysis method is applied. A beam section was taken as a prototype experiment. The temperature and construction data was collected to inverse some necessary thermal parameters. According to the characteristics of concrete temperature field, the basic accelerating genetic algorithm was improved. The improved accelerating genetic algorithm has the merits of high precision and fast calculation. With this algorithm, the calculation temperature and measured value are very close, which shows the method is efficiency. Then inversed parameters were applied in the feedback simulation. According to the simulation results, the proper temperature control method was suggested. By this way, the concrete temperature was controlled well and the beams appear no crack in recent two year. The successful application shows that the inversion and feedback analysis of concrete temperature field can reflect the factual performance of concrete and give important direction to engineering construction.

Simulation on the Thermal Behavior in Vacuum Electron Beam Welding of Magnesium Alloy

The thermal behavior during electron beam welding on magnesium alloy were analyzed and simulated. According to the thermal effect of the electron-beam-generated keyhole, a mathematic model of rotary Gaussian body heat source with incremental power-density-distribution was developed. This model can be useful for simulating the thermal effect of metal vapor plasma on the surface of the workpiece and the deep-penetrating effect of the electron beam. By the action of thermal model, the characteristics of temperature field during vacuum electron beam welding on AZ61 magnesium alloy were studied by the method of finite element analysis. And then, the influence of welding parameters on the temperature distributions and the weld contours were analyzed. The simulations and experiments showed that the different deep-penetration effects and temperature distributions were achieved with the varying welding energy inputs, and the metal vapor plasma has a significant impact on the weld contour of magnesium alloy.