Range Of Temperature Fluctuations Research Articles

Predicting aquatic development and mortality rates of Aedes aegypti.

Mosquito-borne pathogens continue to be a significant burden within human populations, with Aedes aegypti continuing to spread dengue, chikungunya, and Zika virus throughout the world. Using data from a previously conducted study, a linear regression model was constructed to predict the aquatic development rates based on the average temperature, temperature fluctuation range, and larval density. Additional experiments were conducted with different parameters of average temperature and larval density to validate the model. Using a paired t-test, the model predictions were compared to experimental data and showed that the prediction models were not significantly different for average pupation rate, adult emergence rate, and juvenile mortality rate. The models developed will be useful for modeling and estimating the upper limit of the number of Aedes aegypti in the environment under different temperature, diurnal temperature variations, and larval densities.

Quasi-All-Passive Thermal Control System Design and On-Orbit Validation of Luojia 1-01 Satellite.

In order to resolve the large fluctuations in temperature range problem of Luojia 1-01 satellite caused by low heat inertia and poor thermal conductivity of structure, a quasi-all-passive thermal control system (TCS) design is presented under the conditions of limited resources including mass and power consumption. The effectiveness of the TCS design is verified by both ground thermal balanced test and related telemetry data of on-orbit performance. Firstly, according to the structural features and working modes of the satellite, isothermal design was implemented and the effectiveness was verified by thermal analysis using finite element method. Secondly, based on the results of the thermal analysis, thermal design was optimized and verified by the thermal balanced test. Finally, the thermal design was proved to be effective by temperature data acquired from telemetry data of on-orbit performance, and the thermal analysis model was improved and updated based on the results of thermal balanced test and temperature data of on-orbit performance. The on-orbit data indicates that temperature of optical camera stables at about 12 °C, temperature of battery stables at 19 °C, temperature of instruments inside and outside the satellite cabin is ranging from 10 °C to 25 °C. Temperature fluctuation range of optical camera is less than 2 °C when it is not imaging. Temperature fluctuation range of instruments not facing the sun is less than 4 °C. The data suggests that the temperature level of the satellite meets general design requirements, and the quasi-all-passive TCS design of the satellite is practicable.

Research on Temperature Effect in Insulator–Metal Transition Selector Based on NbO<italic>x</italic> Thin Films

In this paper, the NbO x , which was regarded as a promising material based on its insulator–metal transition (IMT) effects, was applied as the switching layer of the device. The threshold switching characteristics were comprehensively investigated with particular emphasis on temperature dependence. The conduction mechanism for high-resistance state (HRS) was fitted and verified to be Schottky emission. With the increase in temperature, the fitting results demonstrated that the Schottky barrier decreased, leading to a reduction in the resistance of HRS. Furthermore, according to Fourier’s law of heat conduction, the fluctuation range of temperature was smaller, causing a narrow distribution of the threshold voltage as the operating temperature increased. In addition, the increasing temperature caused high energy of electrons, which would induce an IMT more easily, leading to a lower threshold voltage. This paper provided the promise for improving the thermal stability of selected devices.

A New Prediction Model for Transformer Winding Hotspot Temperature Fluctuation Based on Fuzzy Information Granulation and an Optimized Wavelet Neural Network

Winding hotspot temperature is the key factor affecting the load capacity and service life of transformers. For the early detection of transformer winding hotspot temperature anomalies, a new prediction model for the hotspot temperature fluctuation range based on fuzzy information granulation (FIG) and the chaotic particle swarm optimized wavelet neural network (CPSO-WNN) is proposed in this paper. The raw data are firstly processed by FIG to extract useful information from each time window. The extracted information is then used to construct a wavelet neural network (WNN) prediction model. Furthermore, the structural parameters of WNN are optimized by chaotic particle swarm optimization (CPSO) before it is used to predict the fluctuation range of the hotspot temperature. By analyzing the experimental data with four different prediction models, we find that the proposed method is more effective and is of guiding significance for the operation and maintenance of transformers.

Research on temperature and pressure responses in the rapid mold heating and cooling method based on annular cooling channels and electric heating

Rapid heat cycle molding (RHCM) is an advanced injection molding technology for producing spraying-free plastic products with excellent appearance. Rapid mold heating and cooling is the key technique of RHCM. Despite widely used in practice, the regular rapid mold heating and cooling methods still have some obvious defects. Thus, the authors developed a new rapid mold heating and cooling method characterized by electric heating and annular cooling, and this study experimentally investigated its temperature and pressure responses in the heating and cooling periods. The results show that the tool surface temperature increases almost linearly with the heating time after a short response time. The larger the heating power or the smaller the distance from heater to tool surface, the faster the heating rate. Introducing air bubbles into working fluid can remarkably reduce the pressure growth of working fluid without affecting the heating rate. In the investigated range of flow rate, the cooling rate firstly increases significantly with the flow rate, and then reaches a plateau, while the running pressure of working fluid increases linearly with the flow rate in the whole range. The optimum flow rate is around 6.0 L/min corresponding to the Reynolds number of 6700. The heat transfer coefficient in cooling period increases sharply at the initial stage, and then reduces gradually, and finally reaches a plateau. The larger the Reynolds number the higher the heat transfer coefficient. In particular, the heat transfer coefficient and the Reynolds number show a linear relationship on the double logarithm scale. Finally, a mathematical model was developed for predicting and controlling the temperature fluctuation range of tool surface. Thus, this study can benefit the industrial application of the new rapid heating and cooling method.

Results of natural gas parameters influence on processes that occur in turbine flow meters

In the article criteria of possible turbine flow meters calibrations with natural gas parameters fluctuations are determined Article presents experimentation results of natural gas parameters influence on processes that occur in turbine flow meters. In the article criteria of possible turbine flow meters calibrations with natural gas parameters fluctuations are determined. It is known that metrological parameters of the turbine flow meter in operating systems will deter from certificated values. With pressure, temperature or other fluctuations of a flow physical parameters the flow meter's results will occur within of a error space determined by Reynolds number equation for current flow passing through turbine grille. With Reynolds numbers constant aspect ratio the relative error of a flow meter will stay irrelevant of type of the environment. It is suggested to use value as a criterion that is not affected by thermodynamic parameters and physical characteristics of a environment but of turbine grille model and mechanical state of a flow meter . Turbine flow meter SM-RI-X-KG1000, DN200 was used for experiment with flow volume varies of 80 m 3 /h to 1600 m 3 /h and pressure varies of 100 kPa to 700 kPa. Results of theoretical calculations and experimental research data for Reynolds number ratio is shown on a graph of a turbine flow meter speed on pressure dependency. It is determined that flow meter designed for low-pressure environment should be calibrated for actual range of operating environment pressure and temperature values. ДСТУ EN 12261:2006. «Лічильники газу турбінні. Загальні технічні умови», that allows usage of gas flow meter designed for 100mbar environment in set up with 4bar of absolute gas pressure should be corrected. For improving of quality and precision of gas flow measurement, calibration of gas flow meters, designed for 5bar of absolute gas pressure, should be performed in an actual working environment keeping in mind range of realistic pressure and temperature fluctuations. Calibrations of gas flow meters that designed for gas pressure environment exceeding 5bar could be performed with environment that keeps defined Reynolds numbers ratio constant.

Mediterranean versus Red sea corals facing climate change, a transcriptome analysis

The anthropogenic increase in atmospheric CO2 that drives global warming and ocean acidification raises serious concerns regarding the future of corals, the main carbonate biomineralizers. Here we used transcriptome analysis to study the effect of long-term gradual temperature increase (annual rate), combined with lowered pH values, on a sub-tropical Red Sea coral, Stylophora pistillata, and on a temperate Mediterranean symbiotic coral Balanophyllia europaea. The gene expression profiles revealed a strong effect of both temperature increase and pH decrease implying for synergism response. The temperate coral, exposed to a twice as high range of seasonal temperature fluctuations than the Red Sea species, faced stress more effectively. The compensatory strategy for coping apparently involves deviating cellular resources into a massive up-regulation of genes in general, and specifically of genes involved in the generation of metabolic energy. Our results imply that sub-lethal, prolonged exposure to stress can stimulate evolutionary increase in stress resilience.

Molecular dynamics sliding simulations of amorphous Ni, Ni-P and nanocrystalline Ni films

Molecular dynamics modeling is used to investigate the sliding feature of different nano-scale specimens: single-crystal nickel evolving from amorphous pure Ni during shear deformation, Ni-P amorphous layer and nanocrystalline nickel. Special attentions are paid to the value of resistance stresses and plastic deformation mechanisms manifested during sliding simulations. The study is performed for considered systems at a temperature of about 300K with narrow acceptable range of temperature fluctuation. It was found that Ni-P amorphous structure is characterized by lowest resistance stresses and smooth sliding provided by the bond-switching mechanism between pairs of atoms due to shear loading. Similar low resistance stress was also observed for an amorphous pure Ni layer, but only at an early stage of sliding before crystallization occurred. The highest shear resistance was confirmed for single-crystal nickel caused by classical deformation mechanisms like stacking fault formation and dislocation movement. Sliding simulations of a nanocrystalline specimen show both, crystal defect driven deformation in the bulk and sliding along quasi-amorphous grain boundaries. In that case the resistance force was between amorphous layer sliding and single crystal sliding, but closer to amorphous layer sliding.

Influence of Urea Concentration on Refractive Index of AdBlue Fluid Evaluated by Regression Analysis

The article deals with the influence urea concentration in the AdBlue fluid on the refractive index. The AdBlue fluid is an aqueous solution of urea and demineralized water. It is used as a reducing agent for SCR (Selective Catalytic Reduction) system. Due to temperature fluctuation of AdBlue during the measurement of refractive index, the multi-dimensional linear regression had to be used to determine the effect of the two factors – concentration and temperature. This article describes in detail the individual steps of the regression model construction done using the so-called regression triplet. The task of this method was to create a regression model which describes the influence urea concentration and small changes in temperature on refractive index of AdBlue fluid. As the results of the multi-dimensional regression analysis show, the temperature factor is statistically insignificant because of small range of temperature fluctuation during measurement, and thus only the urea concentration in the fluid had the major effect on the refractive index.

High-accuracy CFD prediction methods for fluid and structure temperature fluctuations at T-junction for thermal fatigue evaluation

Temperature fluctuations generated by the mixing of hot and cold fluids at a T-junction, which is widely used in nuclear power and process plants, can cause thermal fatigue failure. The conventional methods for evaluating thermal fatigue tend to provide insufficient accuracy, because they were developed based on limited experimental data and a simplified one-dimensional finite element analysis (FEA). CFD/FEA coupling analysis is expected as a useful tool for the more accurate evaluation of thermal fatigue. The present paper aims to verify the accuracy of proposed numerical methods of simulating fluid and structure temperature fluctuations at a T-junction for thermal fatigue evaluation. The dynamic Smagorinsky model (DSM) is used for large eddy simulation (LES) sub-grid scale (SGS) turbulence model, and a hybrid scheme (HS) is adopted for the calculation of convective terms in the governing equations. Also, heat transfer between fluid and structure is calculated directly through thermal conduction by creating a mesh with near wall resolution (NWR) by allocating grid points within the thermal boundary sub-layer. The simulation results show that the distribution of fluid temperature fluctuation intensity and the range of structure temperature fluctuation are remarkably close to the experimental results. Moreover, the peak frequencies of power spectrum density (PSD) of both fluid and structure temperature fluctuations also agree well with the experimental results. Therefore, the numerical methods used in the present paper are of sufficiently high accuracy to be suitable for the CFD prediction of highly fluctuating flow and temperature fields.

Hydraulic Power Engineering Under Conditions of Probable Climate Changes

Problems associated with the effect of climatic and hydrologic characteristics (temperature, precipitation, river run-off) within the Russian landmass and prediction of the performance of water-power entities under these conditions are examined. At the present time, the world's scientific community is of the common opinion that climate changes are occurring on Earth. In a paper presented by the Russian Hydrometeorolo- gic Institute (1), it is noted that "comparison of model calcu- lations with data derived from observations of the tempera- ture of the air in the near-earth atmosphere yields convincing arguments in favor of the anthropogenic nature of global warming, whereby the effect of anthropogenic activity on the temperature of the air is manifested not only in global changes, but also on a continental scale." A large part of the Russian landmass f alls within a region of significant observ- able warming. During the period from 1976 through 2006, the increase in mean annual air temperature with respect to Russia on the whole was 1.33°C for the 31 years, i.e., ex- ceeded the average warming for a 100-year period, which had ranged from 1.00 to 1.29°C. Figure 1 shows the dynam- ics of the variation in mean annual air temperature in Russia during the 20th century. It is apparent from the plot that a particularly rapid increase in temperature was observed in the past 30 - 35 years Global warming of the climate may create, and has al- ready created serious economic, political, and social prob- lems both for Russia, and also for many countries of the world. It should be pointed out that in a zone of global warm- ing, the range of temperature fluctuations also increases. Values of both extremal low, and also extremal high tempera- tures are increasing. The wind regime and moisture regime are becoming more extremal in individual regions.

Clinical study of passive cooling in treatment of severe asphyxiated newborn infants

Objective Therapeutic hypothermia has become a standard neuroprotective treatment in term newborn infants following perinatal asphyxia, but active cooling with whole body surface or head cooling is both complex and expensive.The clinical feasibility of passive cooling in treatment of full term infants with severe asphyxia was investigated. Methods Thirty-two severe asphyxiated term newborns treated with hypothermia were analyzed, who were randomly divided into 2 groups: passive cooling group(n=17) and active cooling group(n=15). Active cooling group adopted MTRE ALLON™-thermo regulatory systems, passive cooling group using natural cooling method.Hypothermia treatment time was 72 hours.At the end of treatment, the clinical manifestations, biochemical parameters and clinical efficacy of infants between the 2 groups were compared. Results During treatment all infants had no cardiac arrhythmia, hypoglycemia, sustained metabolic acidosis, blood-borne infections, local cold injury or bleeding.Infants in passive cooling group had a relatively wide range of rectal temperature fluctuations[average (33.47±0.71) ℃] and infants in active cooling group had a relatively narrow range of rectal temperature fluctuations[average (33.66±0.29) ℃], but there was no statistically significant difference in their mean rectal temperature(t=1.941, P=0.055). One patient died in active cooling group, but there were no significant differences in suckling age, length of hospital stay, neonatal behavioral neurological assessment score, abnormal cranial ultrasound and MRI between the survivors of the two groups(all P>0.05). Conclusions In NICU, environmental temperature is relatively stable, passive cooling for asphyxiated newborns appears to be feasible for maintenance of hypothermia with a lower risk of adverse reactions. Key words: Asphyxia; Hypothermia; Infant, newborn; Passive cooling; Active cooling

Research on the Heat Transfer of High-Speed Railway Pantographs

In the pantograph-catenary system of electric railroads, there is friction heat between high-speed moving pantograph sliders and the contact wires, leading to a temperature increase on the contact surface. On the contact surface under the current collecting conditions, there are also contact resistance heat and arc heat produced by the current effect, leading to further temperature increase of the pantograph sliders. This paper applies finite element method to analyze the steady heat transfer and transient heat transfer of the pantograph sliders of high-speed train and studies the transient heat transfer of sliders and contact wires in actual movement. The computing results determined the temperature fluctuation range and temperature distribution when sliders and contact wires are in normal working condition.

Effects of traditional vegetation usage and management on the growth of facilitator keystone species in a moist tall grassland

To reveal the influence of traditional management measures on the growth of Ischaemum aristatum var. glaucum, whose facilitation effects on plant species diversity have been addressed in our previous studies, experimental winter-mowing and burning treatments were implemented in Ukishima Marsh, a conservationally important freshwater lowland reed marsh of eastern Japan. Comparison of environmental conditions among burnt, mown, and control zones revealed that winter burning, which was even more effective than mowing, created well-illuminated conditions, a high cumulative ground-surface temperature, and a wide range of daily temperature fluctuations. Relative growth rates of I. aristatum var. glaucum shoots and individuals showed a significantly ascending gradient in the order of control, mown, and burnt zones. Continuation of traditional vegetation usage and management is recommended for Ukishima Marsh, as such methods would not only provide favorable environmental conditions for native herbaceous plants commonly, but would also indirectly maintain plant species diversity through promotion of plant facilitation as demonstrated in our previous studies.

Setting for the Application of Phase Change Paraffin in Block Masonry

This paper studies the insulation properties of masonry filling paraffin composite phase change material. With high density polyethylene (HDPE) as wrapping materials and solid-liquid mixing paraffin as phase change materials, solid-liquid mixed paraffin phase change material with different amount of admixture is prepared, and the problem of flowing after paraffin phase change is then solved. The phase change temperature and the phase change latent heat of composite phase change material with different amount of admixture are tested. The results showed that the composite material with 30% of 52 # solid paraffin, 70% of liquid paraffin, 70% of HDPE coating performs best as to the phase transition temperature and latent heat. On this basis, This paper studies the composite phase change wall with phase change materials 0%, 33%, 66% and100%. Results show that the composite phase change material wall’s heat preservation performance has significantly improved. the temperature fluctuation range of internal and external wall surface is 4.2 °C lower than unfilled wall.

Bias from gas inhomogeneities in the pressure profiles as measured from X-ray and Sunyaev–Zeldovich observations

X-ray observations of galaxy clusters provide emission measure weighted spectra, arising from a range of density and temperature fluctuations in the intra-cluster medium (ICM). This is fitted to a single temperature plasma emission model to provide an estimate of the gas density and temperature, which are sensitive to the gas inhomogeneities. Therefore, X-ray observations yield a potentially biased estimate of the thermal gas pressure, P_X. At the same time Sunyaev-Zeldovich (SZ) observations directly measure the integrated gas pressure, P_SZ. If the X-ray pressure profiles are strongly biased with respect to the SZ, then one has the possibility to probe the gas inhomogeneities, even at scales unresolved by the current generation of telescopes. At the same time, a weak bias has implications for the interchangeable use of mass proxies like Y_SZ and Y_X as cosmological probes. In this paper we investigate the dependence of the bias, defined as b_P(r)=P_X(r)/P_SZ(r)-1, on the characteristics of fluctuations in the ICM taking into account the correlation between temperature and density fluctuations. We made a simple prediction of the irreducible bias in idealised X-ray vs SZ observations using multi-temperature plasma emission model. We also provide a simple fitting form to estimate the bias given the distribution of fluctuations. Analysing a sample of 16 clusters extracted from hydrodynamical simulations, we find that the median value of bias is within +/-3% within R_500, it decreases to -5% at R_500<r<1.5R_500 and then rises back to ~0% at r >~ 2R_500. The scatter of b_P(r) between individual relaxed clusters is small -- at the level of <0.03 within R_500, but turns significantly larger (0.25) and highly skewed at r>~ 1.5R_500. For any relaxed cluster we find |b_P(r)| < 15% within R_500, across different implementations of input physics in the simulations. [abridged]

Isolation and Characterization of Microbes with Biofertilizer Potential

Microorganisms work incognito to maintain the ecological balance by active participation in carbon, nitrogen, sulphur and phosphorous cycles in nature. Sampleswere collected from nearriver Ganga mainly Hazipur, Sonepur and Vaishali. Sites were dry field, banana field, wetland and stagnant pond areas. Isolation was done by serial dilution method in nutrient agar plate. The isolates were found to be maximum in humus rich soil of S1 (Banana field) soil (Hazipur) and S2 (Sedimented pond) soil. A total of 111 microbial strains (bacteria) were isolated. Strain which showed the best result was tested for its' biofertilizer potential on the paddy (Oryza sativa, variety - Sugandha) individually through pot experiment. The test isolate namely, S1(C) was selected on the basis of their luxuriant growth on NA. This isolate showed a wide range of temperature for growth between 4 C to 55 C which suggests its potential as biofertilizer in field conditions where the organism has to survive under wide range of natural temperature fluctuations. The selected test isolate was Bacillus although molecular characterization (16s r-RNA studies) was done to confirm the genus and species of the selected isolate. On the basis of BLAST alignment of the sequenced nucleotides the isolate S1(C) was identified as Brevibacillusborstelensis. The reported literatures suggest that the B. borstelensisactsas PGPR.

J032021 流体温度変動による配管熱疲労に関する研究 : 熱荷重を評価するための流体と構造の温度変動の高精度なCFD解析手法([J032-02]エネルギープラント安全に向けた構造/熱流体/材料の達成問題(2))

Temperature fluctuations generated by the mixing of hot and cold fluids at T-junction, which is widely used in nuclear power and process plants, can cause thermal fatigue failure. The existent evaluation method of thermal fatigue provides insufficient accuracy for the evaluation result, because it was developed based on the limited experimental data and the simplified one-dimensional FEA. CFD/FEA coupling analysis is expected as a useful tool for the more accurate evaluation of thermal fatigue. The present paper aims to verify the accuracy of numerical methods of simulating fluid and structure temperature fluctuations at T-junction for thermal fatigue evaluation. The dynamic Smagorinsky model (DSM) is used for LES sub-grid scale (SGS) turbulence model, and a hybrid scheme (HS) is adopted for the calculation of convective terms in the governing equations. Also, heat transfer between fluid and structure is calculated directly based on thermal conduction by allocating grid points within the thermal boundary sub-layer. The simulation results show that the distribution of fluid temperature fluctuation intensity and the range of solid temperature fluctuation are close to the experimental results. Moreover, the peak frequencies of PSD of both fluid and solid temperature fluctuations also agree with the experimental results well. As a result, it has been proven that the numerical methods used in the present paper are of high accuracy.

Study on Asphalt Pavement Temperature Field Distribution Law in Seasonally Frozen Regions

Based on the temperature field data collected from a self-developed pavement system, asphalt pavement temperature field distribution law in seasonally frozen regions was studied in detail. Test data illustrated that: The atmospheric and pavement temperature shows cycle sine rule; Minimum and maximum values of pavement temperature occur at surface, In winter, pavement temperature gradually increases with increasing depth, but has contrary result in summer; As the increase of depth, the fluctuation range of pavement temperature decreases gradually, which lead to the appearance of daily and annual constant temperature point; The max freezing depth appeared at 120cm and there will be freezing core in spring in seasonally frozen regions.

Real-Time Monitoring Device and Method of the Compression Stress of Rubber Materials

An accelerated ageing test equipment with the pressure transducer and digital indicator is designed in the light of the features that the rubber seal used in aviation industry always stand compression stress. This equipment can do real-time monitor on the compression stress of rubber materials in accelerated ageing test. The stress measurement range is 0～980 N, and the temperature fluctuation range is 0～200°C. With this equipment, the compression stress relaxation and stress permanent set can be tested and the relationship between them in 100°C can be found.