Maximum Temperature Values Research Articles

Температурний режим грунтових масивів Як геологічний вплив на основи будівель

Проаналізовані результати спостережень за температурою ґрунту на 11 метеостанціях України. Розроблена методика визначення мінімальних та максимальних розрахункових значень температури ґрунту. Визначені розрахункові значення температури ґрунту для глибин до 3,2 м, проаналізовані та описані їх залежності від глибини й періоду повторюваності. Результати дослідження можуть бути використані в теплотехнічних розрахунках підземних частин будівельних об’єктів.

Changes in Air Temperature and Snow Cover in Winter in Poland

The primary objective of the paper was to characterize the climatic conditions in the winter season in Poland in the years 1966/67–2019/20. The study was based on daily values of minimum (Tmin) and maximum air temperature (Tmax), and daily values of snow cover depth. The study showed an increase in both Tmin and Tmax in winter. The most intensive changes were recorded in north-eastern and northern regions. The coldest winters were recorded in the first half of the analyzed multiannual period, exceptionally cold being winters 1969/70 and 1984/85. The warmest winters occurred in the second half of the analyzed period and among seasons with the highest mean Tmax, particularly winters 2019/20 and 1989/90 stood out. In the study period, a decrease in snow cover depth statistically significant in the majority of stations in Poland was determined, as well as its variability both within the winter season and multiannual.

Investigation of Temperature Evolution and Flash Formation at AA5083 Studs during Friction Surfacing

Friction surfacing (FS), a solid-state joining process, is a coating technology for metallic materials. Frictional and plastic deformation enable the deposition of a consumable material on a substrate. Process temperatures stay below the melting point of the consumable material and are an important factor determining the quality of the resulting deposit. The focus of the current study is the experimental analysis of the flash formation and the temperature evolution in consumable studs during FS deposition of dissimilar aluminum alloys. The main process parameters, axial force, rotational speed and travel speed, were varied while the setting of the process surrounding was kept constant. The temperature evolution for the applied process parameter combinations are investigated for the stud material via infrared camera. The results show that the choice of applied force, rotational speed and travel speed did not lead to significant changes in maximum process temperature values of the consumable stud detectable via infrared camera. However, the flash formation at the tip of the plasticized stud shows significant differences for varied process parameters. Especially reduction of travelspeed or increase in axial force led to formation of larger flashes. Since the material that is pressed out of the process zone into the flash is not deposited on the substrate, the flash formation can be linked to the material efficiency of the FS process.

Theoretical and experimental investigation of spatial temperature distribution in active fiber under conditions of laser radiation generation

The longitudinal and transversal temperature distribution in active waveguide, doped with Yb/Er ions, under conditions of laser generation was calculated as the composition of two mathematical models: computation of longitudinal pump radiation distribution by solution of rate equations for Yb/Er doped active medium and computation of transversal temperature distribution by solution of heat equation for convectively cooled fiber using finite element method. The theoretical results were in a good agreement with experimental data, measured by the piezoelectric resonators used as temperature sensors, placed on the surface of the fiber. The pump radiation transferring length in active waveguide and the location of the most heated fiber area, as well as the maximum temperature value, were calculated using a created model of pump radiation transferring into GT-wave active fiber.

Thermomechanical analysis of nitinol memory alloy behavior

Shape memory alloys are functional materials characterized by the effect of shape memory and superelasticity. Due to these properties, they are widely used, particularly, in bioengineering, aeronautics, robotics and civil engineering. The temperatures of phase transformations and the influence of external temperature and strain rate on the functional and mechanical characteristics of Ni55.75Ti44.15 shape memory alloy are investigated in this paper. The temperature of alloy phase transformations is obtained by differential scanning calorimetry (DSC) in the temperature range from -70°C to 70°C. Diagrams of differential scanning calorimeters at different heating and cooling rates of Ni55.75Ti44.15 alloy is constructed and analyzed. Samples for mechanical tests are made of round rod 8 mm in diameter. The samples working area is 12.5 mm in length and 4 mm in diameter. Mechanical tests are carried out at temperatures close to the maximum value of the completion temperature of martensitic-austenitic transformation Af = 14.7°C. Diagrams of deformation under uniaxial tension are constructed and stresses of phase transformations, Young's modulus and relative elongations of transformation areas at different loading speeds and exterior temperatures are determined. Using Clausius-Clapeyron formula, it is shown that with simultaneous changes in temperature and strain rate, the stresses of phase transformations are largely due to changes in temperature rather than load rates. The coefficients of Clausius-Clapeyron equation for superelastic Ni55.75Ti44.15 alloy with shape memory, which are consistent with those known in the literature, are determined.

Venous leg ulcers treated with fish collagen gel in a 12-week randomized single-centre study.

IntroductionVenous ulcers are difficult to heal chronic wounds. Most challenging are the non-healing and recurrent ulcers, because of which we are seeking for therapies that stimulate and support their healing.AimTo assess the efficacy of fish collagen and its impact on the process of healing of venous leg ulcers.Material and methodsThis 12-week randomized single-centre study included a total of 97 adults with venous leg ulcer, randomized into two groups: the study group (n = 48) and the control group (n = 49). All patients received specialist medical care including skin and limb care, wound development according to the TIME scheme (tissue debridement, infection and inflammation control, moisture balance, edge) and short-stretch bandage compression (compression class II). In addition, the study group received tropocollagen gel applied to the skin around the wound. Every 2 weeks we evaluated the wound surface and temperature distribution on the shin (average temperature, median, minimum and maximum) – symmetrically on the sick and healthy limb.ResultsWe observed a greater number of complete ulcer healing in the study group (week 12: 29.2% vs. 22.4%; week 24: 52.1% vs. 36.7%). Faster healing time in the study group was observed in both big and small ulcers. The thermographic analysis showed statistically significant reduction in periwound inflammation among patients from the study group (p < 0.05). Statistically significant reduction in mean as well as maximum values of limb temperature occurred only in the study group (Tx: R = 0.37, p < 0.001; Tmax: R = 0.40, p < 0.001).ConclusionsThermographic analysis showed better wound healing effects in the group using tropocollagen. Significant impact of collagen on the healing process was observed only after 8 weeks of application.

Thermomechanical behavior of an electrically conductive cylindrical implant under the action of external unstable electromagnetic fields

A physical and mathematical model for determining the thermostressed state of an electrically conductive cylindrical implant under the action of external unstable electromagnetic fields, in particular the impulse with amplitude modulation, is proposed. This model allows predicting the maximum allowable values (according to physiological norms) of temperature and stress intensities in the considered implant depending on the parameters of external unstable electromagnetic fields and the time of their action.

Thermomechanical behavior of an electrically conductive cylindrical implant under the action of external unstable electromagnetic fields

A physical and mathematical model for determining the thermostressed state of an electrically conductive cylindrical implant under the action of external unstable electromagnetic fields, in particular the impulse with amplitude modulation, is proposed. This model allows predicting the maximum allowable values (according to physiological norms) of temperature and stress intensities in the considered implant depending on the parameters of external unstable electromagnetic fields and the time of their action.

ТЕПЛОВА МОДЕЛЬ СИСТЕМИ «АСИНХРОННИЙ ГЕНЕРАТОР–АСИНХРОННИЙ ДВИГУН» ПРИ НЕСИМЕТРІЇ В ОБМОТКАХ СТАТОРА

Purpose. Development of the IG model for estimation of influence of variations of parameters of the generator on quality of process of self–excitation at definition of the basic and boundary operating modes and system of initial excitation at invariable parameters of the generator. Result. The article presents studies of the system "asynchronous generator-asynchronous motor" with parametric asymmetry to determine the quality of generated electricity in load modes of operation on a mathematical model. The assessment of the thermal state in steady-state conditions was carried out using an equivalent thermal equivalent circuit. Thermal transients were investigated when starting an asynchronous electric motor from an autonomous power source based on an asynchronous generator. On a thermal mathematical model, a study of the influence of the asymmetry of the output voltage and its deviation from the nominal value on the heating of the connected asynchronous motor was carried out. A regression model has been developed for studying the operating conditions of electricity consumers when powered by an asynchronous generator with an asymmetry of the stator windings. Practical value. The use of the obtained equations will make it possible to determine the most rational combination of factors affecting the heating of the stator windings of asynchronous machines, at which they will not overheat in excess of the maximum permissible temperature values of the corresponding insulation classes. Figures 9, tables 2, references 23.

Thermal analysis on car brake rotor using cast iron material with different geometries

The vehicle plate brake rotor is a pivoting gadget. Slowing down is a cycle which changes over the dynamic energy of the vehicle into mechanical energy which must be scattered as warmth. This paper presents the examination of the temperature and warmth motion at the plate interfaces utilizing an itemized 3-dimensional limited component model of a genuine vehicle brake rotor. Rotor disc are made utilizing CATIAV5R20 and recreated utilizing ANSYS R 20 which depends on the (FEM) analysisHere take cast iron material and seen that the maximum temperature and heat fluxes values for all three geometries like Solid rotor drilled rotor and drilled & slotted rotor respectively like are 589.48 °C, 555.67 °C and 539.97 °C and 2.9e5 w/mm2, 4.96e5 and 5.04e5w/mm2. Here we can clearly observe that drilled & slotted rotor geometry has very high value of heat flux compare to other rotor geometries. Thermal Analysis on car brake rotor is done by using and simulate the different parameters of various materials. The main findings point to experimented the potential investigation of car brake rotor to give best working performance. Two sorts of brake social occasions are being utilized, drum brakes and circle brakes. Drum brakes produce slowing down force on the internal surface of brake drum, the force associated is radially outward to contact the drum. The wheel-wheel studs are associated with the drum, as such when the drum stops the wheel similarly stops. It is important to acquire rough answers for issue instead of accurate shut discover arrangement. It is unimaginable to expect to get investigative numerical answers for some building issues.

Multi-objective optimization of mixed convection air cooling in an inclined channel with discrete heat sources

In this paper, a multi-objective optimization of mixed convection air-cooling of two identical discrete heat sources mounted in an inclined channel is conducted to obtain the optimal design parameters, using Response Surface Methodology (RSM) and desirability function approach. Reynolds number (Re), inclination of the channel (r) and the width of the discrete heat source (b) are selected as the input parameters. The computational simulations are done for different Reynolds numbers (25-Re-250), inclination angles of the channel (0o-r-360o) and the width of the heat source (5-b-10 mm). A central composite design (CCD), which comes under the RSM approach, with design parameters was used for analysis of variance (ANOVA). A second-order regression models were developed to correlate the design parameters (Re, r and b) with mean Nusselt number (Nu) and maximum temperature (TMax). The optimum values of design parameters produce the lowest value of maximum temperature (TMax) with a higher mean Nusselt number (Nu) are Reynolds number (Re)=209.94, inclination angle of the channel (r)=330o and heat source width (b)=5.13 mm.

Monitoring of a ceramic surface temperature field induced by pulsed Nd:YAG laser

Temperature distribution induced by laser radiation is a very important parameter for an efficient and safe application of lasers in different ceramic processing techniques. This paper presents the results of an infrared thermography application for monitoring temperature distribution on a ceramic surface during Nd:YAG laser irradiation with different fluences and 8ns pulse duration. The FLIR, E40 and SC7200 infrared cameras were used with the aim of recording the maximum temperature in the irradiated zones. It was expected that infrared thermography could give some information related to the heat affected zone and possible damage to the base material. However, the results have shown that infrared cameras, even those with high performance such as SC7200, cannot record the maximum temperature value at the moment of laser operation, but only the average temperature of the bulk sample material after laser pulses. The results of the numerical simulation have confirmed the value of the thermographic measurements. The micro-structure and micromorphology of the ceramic surface before and after the laser treatment were analysed by optical and SEM as well as by examining the roughness of the irradiated and non-irradiated surfaces, while the micro-mechanical changes were analysed by comparing the micro-hardness of the irradiated and non-exposed surfaces.

Performance Study of a Mimo-Shaped Cooling Plate in Pemfc Stack for Heat Transfer Enhancement

During the operation of high-power proton exchange membrane (PEM) fuel cell, huge heat is generated in the chemical reaction, which need be removed by efficient cooling design. To solve the problem of local overheating during PEMFC, a novel multi-input and output (MIMO) cooling flow field is proposed. The maximum temperature, temperature uniformity and pressure drop characteristics of the U-shaped and Z-shaped cooling flow fields with different MIMO channels configurations are researched by computational fluid dynamics (CFD) method. The results demonstrate that comparing with U-shaped cooling flow field, Z-shaped design can provide better temperature distribution with the same MIMO channel configuration. Moreover, the serpentine cooling flow field provides better cooling performance than parallel cooling flow field, but leads to higher pressure loss. Compared to other cases, Z-shaped serpentine MIMO channel presents the best cooling performance, reducing the maximum temperature value to 322.7 K.

Analysis of combustion peculiarities in flame zone of aluminium particle

Metallic particles being added to rocket fuel contribute to increasing its energetic efficiency. In the present paper, the physical model of aluminum particle combustion is developed. The model takes into account accumulation and distribution of condensed oxide in the flame, which is divided into characteristic zones at that. The thermodynamic analysis of flame parameters for a single particle burning in medium «79% Ar + 21% O2» was carried out. The mathematical description of the model is presented, which lets to calculate dependencies of temperature and oxidizing components concentration on relative flame radius R‾ which is ratio of inner flame points coordinate R to current particle radius R0. The calculation method is based on combined use of heat and oxidizer flows balance and on data of equilibrium thermodynamic analysis of flame zone. The calculation of the mentioned dependencies were carried out for aluminium particles 220 μm (220 μm) in diameter at ambient environment pressure equal 0,1 MPa. The following radii were determined: radius of stoichiometry of metal and oxygen flows, radius of maximum temperature value reach and that of flame boundary. New parameter η is introduced which determines degree of metal transformation into condensed oxide and depends on thermodynamics parameters of flames (on temperature and oxidizing components concentration). The maximum of oxide particles distribution is established to be in zone of 5,5 ≤ R/R0 < 6,6, at that η value reaches 90%. The results of present work are compared with data of theoretical and experimental investigations of other authors. The accountability of equilibrium thermodynamics is shown to be mandatory part of models of aluminum particles combustion.

Гидрометеорологические условия в южной части Керченского пролива и предпроливной зоне Черного моря как потенциальном районе промышленного культивирования моллюсков

Considered materials on the hydrometeorological conditions of the Kerch Strait and the Black Sea. The data on the wind regime in the study areas are presented. The materials on currents and water exchange in the southern part of the Kerch Strait and the Black Sea waters are presented. The average monthly, annual, minimum and maximum values of air temperature at the coastal hydrometeorological stations are analyzed. In the seasonal course of salinity, in contrast to the regularities in the sea zone (in the surface and bottom layers), there is no summer minimum in the bottom layer of the strait. This indicates the development of coastal upwellings in the Black Sea in the summer, which facilitates the penetration of the Black Sea waters into the strait in the bottom layer. The oxygen saturation of the waters in the strait (both in the surface and in the bottom layers) is higher than in the sea area. This indicates a more intensive course of production processes. The stable Azov currents are most favorable for the plantations located in the strait near the Crimean coast during the collection of larvae on the collector and for the improvement of trophic conditions in the plantation areas. For the purification of coastal waters from suspended matter, the Black Sea currents are preferred. The frequent change of the Azov and Black Sea currents creates favorable conditions for the effective operation of mariculture farms. On the basis of the studies carried out, conclusions were drawn about the possibility of industrial cultivation of mollusks in the water area of the Kerch Strait and the Black Sea.

Reactivity Initiated Transient Response of TRIGA with the Progress of Core Burnt

Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} This paper illustrates the effects on safety of TRIGA Mark-II research reactor of Bangladesh at its different steps of core burnt during reactivity induced transient. The modeling and simulation were carried by coupled point kinetics, neutronics, and thermal hydraulics code EUREKA-2/RR based on neutronics data calculated previously by Monte Carlo code for different burnt states of TRIGA core. Three burn steps until 150 MWD have been considered for present analysis which are regarded here as beginning of cycle (BOC); middle of cycle, MOC (75 MWD); and end of cycle, EOC (150 MWD). Initially, the results of steady state analysis obtained from EUREKA code for these three burn steps have been verified with that of COOLOD code. Based on consistency of the results from the two codes, transient simulation has been conducted considering reactor with non-function of scram. Reactivity inserted amount ranges within 0.001 to 0.02 dk/k with three durations of insertions of 0.1s, 1s, and 5s. Major parameters such as reactor core maximum power and fuel clad maximum temperature have been reported. The analysis presents transient pattern of these parameters due to change in amount and duration of inserted reactivity. The maximum imposed reactivity that causes the fuel clad to exceed its design temperature at each burn step has been evaluated in this study. It is also observed here for each amount and durations of inserted reactivity, maximum value of both power and clad temperature found to decrease with the progress of core burnt. These results obtained from this analysis will be useful for reactor operators and management team during core upgrading and modification program.

Analysis of climatic variation in a changing livestock and agricultural area: Misiones, Paraguay

Over recent decades, the Misiones Department, located in southern Paraguay, has shifted from an almost exclusively natural pasture-based traditional livestock production region, to the major rice production area of the country, soybeans maize, and family farm crops are also grown. Producers face production risk due to climate variability and change, and due to a lack of studies and analysis of meteorological variables in the area. The major risk are related to precipitation, including excess, deficiencies, intense events and frosts. We used RClimDex to analyze extreme event trends, specifically precipitation and temperature values; and the Standard Precipitation Index (SPI) to analyze drought. Results show that drought is a recurrent phenomenon and that it alternates with periods of significant rainfall excesses. First frost is June seven, the last frost occurs on August two, and the frost period is on average 57 days. We found significant increases in intense precipitation and on wet days. A negative trend was observed in summer days, monthly maximum value of daily maximum temperature, hot days, cold nights and daytime temperature range. These results properly communicated may help producers avoid and adapt to climate risk.

Three-dimensional transient analysis for control rods drop into CSR1000 core

Transient performance of China supercritical water-cooled reactor (SCWR) with the rated electric power of 1000MWe (CSR1000) core during the control rods (CR) drop into the core is analyzed and evaluated with the coupled three- dimensional neutronics and thermal-hydraulics SCWR transient analysis method. The 3-D CR drop transient analysis shows that while the high worth CR drop into the core, the core power in the initial stage of the CR drop process decreases rapidly. The core power descent rate exceeds the shutdown setting value, which will trigger the protection shutdown. While the low worth CR drop into the core, due to the reactivity feedback of the water density, the core power decreases slowly, and the core power descent rate cannot reach the shutdown setting value, which will not trigger the protection shutdown. In the transient process, the peak value of maximum cladding surface temperature (MCST) remains lower than the transient safety limit of 850 °C, whether it is a high worth CR drop or a low worth CR drop. The safety performance of CSR1000 core can be ensured in the process of CR drop into the core under the salient reactivity feedback of water density and the essential reactor protection system.

Research on variation of grinding temperature of wind turbine blade robotic grinding

As a large composite curved surface component, the wind turbine blade is easy to suffer from grinding burn if the grinding parameters are improperly selected during the robot grinding process, which will seriously affect the surface grinding quality. In order to effectively predict the surface grinding temperature of robot grinding wind turbine blade, the curved surface grinding heat source model was established according to the material removal depth of any grinding point in the grinding contact area, and the temperature field under different grinding process parameters was numerically simulated using finite element method. The comparison between simulation and experiment indicates that the temperature on both sides of grinding contact area is higher than the middle temperature, and the maximum grinding temperature value appears on the cut-out side of the cup wheel. The maximum grinding temperature increases as increasing the wheel speed, feed rate and maximum grinding depth, feed rate is the biggest influence factor on the grinding temperature. The maximum grinding temperature of finite element simulation is in good agreement with the experimental results and the maximum relative error is &lt;6%. The research results reveal the variation law between the curved surface grinding parameters and grinding temperature of curved surface grinding, which provides reference and basis for the prediction of grinding temperature of the wind turbine blade ground by robot.

Temperature during the vibration-assisted compression of alfalfa

Compression of alfalfa into briquettes is an effective way to solve the problem of storage and transportation. In the process of compression, heat is generated and the temperature is raised in the material. In fact, the appropriate temperature can improve the quality of alfalfa briquettes and reduce the energy consumption of densification. In this study, the effect of assisted vibration on the compression temperature was tested. The results showed that when the vibration frequency was below 15 Hz, the temperature at the center and side in compressed alfalfa increased slowly with compression time. When the vibration frequency was above 20 Hz, it increased first and then decreased with the increase of time. Moreover, the maximum temperature value increased remarkably when the frequency was above 20 Hz. In the same vibration frequency and compression time, the center temperature in the compressed alfalfa was higher than the side temperature. The experimental results provide a reference for the determination of reasonable vibration parameters, and explanation of the effect of vibration on reducing energy consumption.