Threshold Value Of Temperature Research Articles

“Physical Detonation” Limits in the Flow of Preliminarily Vibration-Excited Hydrogen in a Shock Tube

“Physical detonation” is a phenomenon in which detonation is induced by not chemical, but physical, energy concentrated in internal degrees of freedom (in the present case, in vibrational degrees of freedom of hydrogen molecules). The possibility of emergence of such a phenomenon in hydrogen preliminarily excited to a certain temperature in a shock tube is investigated by the Monte Carlo method of nonstationary statistical simulation. The threshold value of such temperature, above which physical detonation is observed in the numerical experiment, is determined.

Evolution and assessment of urban heat island between the years 1998 and 2016: case study of the cities Bratislava and Trnava in western Slovakia

The paper concerns research on urban heat islands (UHIs) and presents case studies of two Slovak cities of different sizes: the capital, Bratislava, and the regional centre, Trnava. The model MUKLIMO_3 was applied to the UHI modelling and a heat wave that occurred between 15 and 23 August 2018 was chosen. Land cover/land use (LC/LU) classes based on the local climate zone (LCZ) concept were used as input for the modelling. The model was validated by data taken from five stations in Bratislava and two in Trnava, and a good rate of agreement between the modelled and measured data was statistically proven. Manifestations of UHI were studied during the whole of the mentioned period by summing the hours when threshold temperature values exceeded 25 and 30 °C. The results for Bratislava show greater variability related to the size of the city and terrain dissection compared with Trnava, which is smaller and situated in a flat terrain. A single representative day, that is, 20 August 2018, was chosen, for which UHI was modelled with three inputs of LC/LU classes: situation in 1998, 2007, and 2016 in order to assess the effect of change of LC/LU classes on the distribution of temperatures. Spatial manifestation of UHI was assessed in the frame of LC/LU classes for 2016 at 12:00, 18:00, and 24:00 in Central European Summer Time. The greatest heat load was modelled in densely built-up LC/LU classes, while forest areas were coolest. In Bratislava, due to a combination of a dissected terrain and UHI, great variability was modelled, with maximum temperature differences of up to 12 °C and, in the territory with homogeneous elevation, up to 6 °C. The UHI field in Trnava is less variable, with modelled temperature differences of up to 3 °C. A comparison of individual time horizons proved the effect of the urbanization process on the change of air temperature by several tenths of a degree Celsius on average.

Threshold temperature scaling: Heuristic to address temperature and power issues in MPSoCs

In this article, we propose a scheduling based temperature and power-aware heuristic for multi-core systems. Instead of using a fixed value of temperature threshold in load balancing techniques, the proposed heuristic suggests adjusting the value of threshold temperature as a function of the workload. As the workload reduces, the value of the threshold is lowered accordingly and vice versa. Lowering the value of threshold temperature decreases the temperature peaks, temperature spatial, and temporal gradients. Furthermore, it also reduces the total power consumed by the processing unit. The effectiveness of the approach is evaluated in a simulation-based environment that includes a scheduling and a thermal modeling tool. For evaluation, the heuristic is integrated with a state of the art load balancing technique based on global scheduling and a comparison is performed with the popular thermal-aware techniques. The results analysis shows that the use of proposed heuristic lowers the temperature peak by up to 7 °C, temperature spatial gradients by up to 35%, temporal gradient by 65%, and power utilization by up to 5.5% when compared with the state-of-the-art thermal balancing techniques and predictive thermal-aware models.

Automatic Irrigation System using WSN Technology

Agriculture in India contributes maximum for GDP growth. Various parameters impact the proper cultivation of crop. Agriculture requires 90% of water resources. Automated Irrigation System is developed to utilize the available resources in most efficient manner. Threshold value of Temperature & Humidity sensor are used to control the quantity of water. WSN technology has been used to provide updates of farm conditions to the farmer. Automation in the field of farming brings the biggest revolution in our country. The available resources will be utilized in most appropriate manner. The Automation will lead to high yield of crops by utilizing the resources in efficient way. The farm conditions can be displayed to farmer using Graphical representation method.

Thermal effect on the evolution of hydraulic fracture conductivity: An experimental study of enhanced geothermal system

This paper aimed to investigate the thermal effect on the evolution of hydraulic fracture conductivity during heat extraction. Meanwhile, the degradation mechanisms of fracture conductivity were analyzed in terms of the mechanical damage of fracture surfaces. Experimental results of micro-indentation tests on the studies granite show the existence of a threshold value of temperature. The Young's modulus and hardness of fracture surface significantly decreased when the thermal treatment levels were higher than 300 °C. Similarly, the degradation of fracture conductivity was limited (<10%) before 300 °C and then significantly deteriorated at 400 °C and 500 °C. Moreover, cyclic thermal treatment tended to aggregate the mechanical damages of fracture surfaces further. At the thermal treatment level of 300 °C, obvious thermal softening of fracture surfaces and degradation of fracture conductivity were observed only when the number of cycles was larger than 10, while both of these two phenomena became more severe with the increasing of the number of cycles at the thermal treatment level of 400 °C. The evolution of fracture conductivity can be accounted for by the temperature-related integrity of fracture surfaces and proppant pack. It was indicated that the thermal softening of fracture surface tended to enhance the proppant embedding, which might be beneficial for the alleviation of proppant crushing.

Experimental Study on Kinetic Behaviors of Natural Gas Hydrate Production via Continuous Simulated Seawater Injection

Natural gas hydrate (NGH) is a kind of potential energy with shallow buried depth, high energy density, huge reserves, and cleanliness. In this study, continuous seawater injection is adopted for NGH production experiments with applying a self-designed reactor which can simulate an NGH-bearing reservoir with a mini well, given that the surface seawater stores tremendous heat. Continuous seawater injection for NGH production can keep the balance between productivity and sand production through controlling production pressure with its thermodynamic and technical feasibilities. Kinetic behaviors of NGH production by continuous seawater injection are investigated using the simulated NGH-bearing reservoir. Meanwhile, the dissociation of NGH and its influence factors are analyzed. The threshold value of temperature for NGH dissociation is also discussed. The experimental results show that the changes in temperature and pressure keep constant at the initial stage of the continuous seawater injection process. How...

Water Relation Characteristics of Prunus laurocerasus L. under Progressive Soil Drought Stress of Crimea’s Southern Coast

The study examines the ecophysiological response of Prunus laurocerasus L. to the effects of progressive soil drought and determines optimum zones and threshold values of soil moisture, temperature, and light, limiting the photosynthesis and transpiration during its summer active growth period in the southern coast of Crimea. The paper characterizes the development of water stress and photosynthesis inhibition as well as the subsequent recovery after watering. It emphasizes the chlorophyll loss by lamina under the given condition, which was manifested in the yellow-green color of the midrib and brownish spots on the leaves. This leads to the loss of ornamental qualities in the plants. The obtained data on the plant’s functioning mechanisms in response to the environmental effects provides the basis for the ecological assessment of the evergreen species’ physiology and the possibility to choose from a variety of cultivation practices.

Experimental and numerical study of the ignition of hydrogen-air mixtures by a localized stationary hot surface

The ignition of hydrogen-air mixtures by a stationary hot glow plug has been experimentally investigated using two-color pyrometry and interferometry. The ignition process was characterized by the surface temperature at ignition, as well as by the location where the initial flame kernel was formed. The experimental results indicate that: (i) the ignition temperature threshold is a function of equivalence ratio; (ii) the ignition location is a function of the rate at which the glow plug is heated because high heating rates favor non-uniform heating. As a result, ignition occurs on the side rather than near the top face of the glow plug. Comparison with two-dimensional numerical simulations exhibits discrepancies in terms of the temperature threshold value and dependence on equivalence ratio. Simulations performed imposing a non-uniform surface temperature show that a temperature difference between the side and the top of the glow plug as low as 12.5 to 25 K resulted in side ignition for hydrogen-air mixtures. The effect of surface chemistry was estimated numerically by imposing a boundary condition of zero species concentration for intermediate species, H and HO2, at the hot surface, which increased the ignition threshold by up to 50 K for an initial H2 concentration of 70%. The present study shows that surface temperature non-uniformity, heterogeneous chemistry and reaction model used, could influence the experimentally reported and numerically predicted ignition threshold as well as the location of ignition.

ІНДИКАТОРИ ТЕМПЕРАТУРНИХ АНОМАЛІЙ РЕГІОНАЛЬНОГО КЛІМАТУ

Climatic indices are usually created for a particular group or sector of influence, and because of their complexity they cannot be universal and apply for more than one region. In addition, a methodology is needed that would allow studying of changes in the index over a long period of time using climatological data (both models and observations). That is why there are many metrics (or indexes) that try to provide quantitative information about the periods of extreme heat. Since there are many different climatic regimes in one region, it is necessary to focus on observations of extreme temperatures over the research territory. Thus, the anomalies of the air temperature regime that were recorded at 18 meteorological stations of Ukraine during the reference period of 1981-2010 were considered in this study. To assess the effects of hot events (especially heat waves) for a selected region, it is important to know how the climate indicator is evaluated. To assess the effects of hot events, in particular, heat waves, for a particular region, it is important to know how the climate indicator is evaluated this event because there is a certain risk that the inadequate index distorts the climatological information, which in turn leads to ineffective planning of adaptation and mitigation. Therefore, it is necessary to use the index of a climatic event, which could be easily calculated based on the regional climatic data and which could provide comprehensive information that characterizes the heat event which is observed. The latest studies show, the HWMI index is considered an alternative index of temperature regime. HWMI indices were calculated based on the analysis of the maximum daily air temperature series for the calendar year. This was achieved due to the temperature thresholds established on a single metric, which is the most important for which the heat waves were identified and estimated. The annual thresholds of maximum daily air temperature for different reference periods (1961-1990 and 1981-2010) were investigated. It was found out, there is the difference in the threshold values of maximum air temperature during the year for the indicated reference periods only in winter (January-February) and in summer (July-August) and did not exceed 3°С. The field of maximum temperature thresholds for the reference period, which focuses on the south-east of the country, is established. The spatial variability of temperature thresholds along the zonal and meridional sections was studied, which allowed optimizing the grid for the construction of the regional field of threshold extreme temperatures.

Smart Aagricultural Eenvironment Monitoring System using IOT

Agriculture is the chief support of an economy and the pivotal sector for ensuring food security. The agriculture sector recorded satisfactory growth due to improved technology, irrigation, inputs and pricing policies.But now due to migration of farmers from rural to urban there is hindrance in agriculture. To overcome this problem we go for smart agricultural environment monitoring techniques using IOT. The Internet of things (IOT) is remodeling the agriculture enabling the farmers with the wide range of techniques such as precision and sustainable agriculture to face challenges in the field. IOT interconnects human to thing, thing to thing and human to human. IOT enables the objects to be sensed and controlled remotely across existing network model. The paper comprises of sensors that sense the field parameters such as phlevel,temperature, humidity,moisture and fertility in the farm. The sensed values are validated and later sent to the WI-FI module and from WI-FI module the validated data are sent to the farmer’s mobile or laptop using cloud. The farmers are also notified by SMS if the field needs a care. An algorithm is developed with threshold values of temperature, humidity, moisture and fertility that are programmed into a node MCU to control water quantity. Now the farmer can automate the motor from anywhere in the world.

The Research of Anomaly Detection Method for Transformer Oil Temperature Based on Hybrid Model of Non-Supervised Learning and Decision Forests

The anomaly detection of transformer’s oil temperature is critical and valuable issue for the safe operation of transformers and power system. In terms of the defects of traditional anomaly detection approaches of transformer’s oil temperature, such as high investment, poor generality, and non-real time, this paper proposed a hybrid model with non-supervised learning and decision forests method to detect anomaly of transformer’s oil temperature. Based on non-supervised clustering algorithm, firstly, the clusters of transformers’ working conditions are explored from big data sets of transformers. After that, the abnormal temperature threshold value of each cluster is deduced by hypothesis tests method and utilizes to tag anomaly in data sets of working conditions. Finally, the data sets with anomaly tags are inputted into random decision forests model to construct the classifier of abnormal oil temperature and generate the rules for anomaly detection. This method was validated by empirical data of main transformer in Shanghai, and the results represented its conspicuous competitive advantages to traditional oil temperature anomaly detection methods in the factors of real-time and accuracy.

A scheduling based energy-aware core switching technique to avoid thermal threshold values in multi-core processing systems

The increasing on-chip temperature has become a critical issue in the multiprocessor system on chip (MPSoC). It does not only disturb the reliability and performance of the system but it also increases the power consumption. Load balancing is a common scheduling technique to address the thermal issues where the load is transferred to relatively less used cores. However, during the transfer of workload, the destination cores may be in sleep mode and thus take some time to switch to the running mode. It results in wastage of some processing time. This paper presents a thermal-aware load balancing technique that avoids thermal emergencies while eliminating the switching delays. The proposed technique estimates the time taken by a task set to reach the temperature threshold values with the help of offline recorded thermal profiles of datasets. Moreover, cores are selected in a round-robin manner to equilibrate thermal gradients. The technique is based on Global Earliest Deadline First (GEDF) scheduling algorithm and considers ambient temperature, thermal cycles and energy consumption. The proposed technique is tested in a simulation environment comprising of scheduling and thermal simulation model. The results show that the technique reduces the average temperature up to 17%, thermal cycles up to 15%, energy consumption up to 20% and lowers the temporal and spatial gradients as compared to the commonly used predictive thermal-aware and thermal balancing techniques.

Forest fire characteristics in China: Spatial patterns and determinants with thresholds

Forest fire characteristics and their determinants are important considerations for forest management. However, the interaction among natural and anthropogenic factors and their impacts on the occurrence and distribution of forest fires in China, a vast country with enormous variation in its environmental and social contexts, has remained a lasting challenge in science and forest management. In this study, ground-based data of forest fires at the county level in China’s forest fire hazards survey (1989–1991) were applied in studying forest fires and five relevant factors: climate, fuel, topography, human activity, and firefighting facilities at national and provincial scales. During the study period, the county-level number of forest fires in China increased with decreasing latitude, and the burnt area was larger in the subtropical region and some counties of Northeast China. Industry fires and recreation fires showed contrasting latitudinal patterns, and cultural fires dominated in North China. Lightning fires constituted less than 1% of forest fires, and dominated in only six counties. Results of a random forest model indicated that spring temperature and forest stocking level were respectively the most critical variables affecting the fire number and burnt area across China, and overall threshold values of mean spring temperature of 15 °C and forest stocking of 500 million were suggested respectively for abrupt changes in fire frequency and burnt area. Climatic conditions generally dominated the variation in human-caused fires, but lightning fires were primarily influenced by fuel load. However, the most important factors for fire features varied substantially at the provincial scale, highlighting the complexity in the roles of climate or fuel conditions and their combinations for fire risk. Our results provided a first ground-based snapshot of forest fire patterns in China at a high spatial resolution, revealed contrasting features of natural- and human-caused forest fires, and highlighted the spatial variation of fire drivers. The potential uncertainty indicated the necessity of long-term monitoring with multiple approaches for better understanding of forest fire activities and optimal practice in forest fire management in China, both at national and provincial scales.

Farm field monitoring and irrigation automation using IOT

The Agricultural farming crops are produced in low qualitydue to lack of knowledge of farmers and crops destroyed by insects. To overcome that, many implemented factors are used. The factors can be temperature,soil,humidity,etc.,In biotechnology,some techniques are used withthe help of IoT. It is mainly used to increase the crops productivity in good quality.Existing related research works on sensor cloud have primarily focused on the challenges that wireless sensor network (WSN)-based applications. A direct estimate of water use by subsurface measurements of soil water content has been limited by the high cost of reliable soil moisture sensors. Using some sensors and techniques water can be irrigated automatically.IOT plays a vital role in smart farming.By using set of specified sensors,the irrigation man-agement can be done properly.The sensed data from the sensors and the irrigation controller are interfaced with Wi-Fi connection. In naive Bayes, by using decision making process the farmer can decide when and where to irrigate with the help of mobile application. An algo-rithm was developed with threshold values of temperature and soil moisture that was programmed into a microcontroller-based gateway to control water quantity.

Porosity and wave velocity evolution of granite after high-temperature treatment: a review

The evolution of porosity and changes in wave velocity in granite after high-temperature treatment has been experimentally investigated in different studies. Statistical analysis of the test results shows that there is a temperature threshold value that leads to variations in porosity and wave velocity. At a temperature that is less than 200 °C, the porosity of granite slowly increases with increases in temperature, while the wave velocity decreases. When the temperature is greater than 200 °C (especially between 400 and 600 °C), the porosity quickly increases, while the wave velocity substantially decreases. The temperature ranges of room temperature to 200 and 200–400 °C correspond to the undamaged state and the micro-damage state, respectively. The results confirm that there is an important link between the variations of physical and mechanical properties in response to thermal treatment. By studying the relationships among rock porosity, wave velocity and temperature, this provides the basis for solving multi-variable coupling problems under high temperatures for the thermal exploitation of petroleum and safe disposal of nuclear waste.

Vertical climatic belts in the Tatra Mountains in the light of current climate change

The paper discusses temporal changes in the configuration of vertical climatic belts in the Tatra Mountains as a result of current climate change. Meteorological stations are scarce in the Tatra Mountains; therefore, we modelled decadal air temperatures using existing data from 20 meteorological stations and the relationship between air temperature and altitude. Air temperature was modelled separately for northern and southern slopes and for convex and concave landforms. Decadal air temperatures were additionally used to delineate five climatic belts previously distinguished by Hess on the basis of threshold values of annual air temperature. The spatial extent and location of the borderline isotherms of 6, 4, 2, 0, and − 2 °C for four decades, including 1951–1960, 1981–1990, 1991–2000, and 2001–2010, were compared.Significant warming in the Tatra Mountains, uniform in the vertical profile, started at the beginning of the 1980s and led to clear changes in the extent and location of the vertical climatic belts delineated on the basis of annual air temperature. The uphill shift of the borderline isotherms was more prominent on southern than on northern slopes. The highest rate of changes in the extent of the climatic belts was found above the isotherm of 0 °C (moderately cold and cold belts). The cold belt dramatically diminished in extent over the research period.

Smart irrigation using WSN based on IOT

To set right the usage of water for crops of agriculture an automated irrigation system has been implemented. A moisture soil sensor; and a temperature measure sensor which is called as network of the distributed wireless is used at base of the plant. Along with these, we implemented a gateway unit. which gathers information and regulate it and by activating the triggers actuators, it can send and receive the transmits data to and from the web application. I proposed the algorithm which having the temperature and soil moisture threshold values that embedded in a gate way based on micro controller. It implemented panels of the photovoltaic; and having a duplex communication link; and works with the interface i.e. cellular-Internet which offers that data inspection &amp; irrigation timing. All this can be programmed by using a web page. Implemented automated Crop water saving system tested for 136 days in sage crop field. It can be saved 90% water compared to others. The main 3 advantages of this automated system make it place successfully in any place for 18 months. As it is energy self-rule, cost less, so it can be efficiently useful in limited water geographical lands.

An examination of extratropical cyclone response to changes in baroclinicity and temperature in an idealized environment

The dynamics and precipitation in extratropical cyclones (ETCs) are known to be sensitive to changes in the cyclone environment, with increases in bulk water vapor and baroclinicity both leading to increases in storm strength and precipitation. Studies that demonstrate this sensitivity have commonly varied either the cyclone moisture or baroclinicity, but seldom both. In a changing climate, in which the near-surface equator to pole temperature gradient may weaken while the bulk water vapor content of the atmosphere increases, it is important to understand the relative response of ETC strength and precipitation to changes in both factors simultaneously. In this study, idealized simulations of ETC development are conducted in a moist environment using a model with a full suite of moist physics parameterizations. The bulk temperature (and water vapor content) and baroclinicity are systematically varied one at a time, then simultaneously, and the effect of these variations on the storm strength and precipitation is assessed. ETC intensity exhibits the well-documented response to changes in baroclinicity, with stronger ETCs forming in higher baroclinicity environments. However, increasing water vapor content produces non-monotonic changes in storm strength, in which storm intensity first increases with increasing environmental water vapor, then decreases above a threshold value. Examination of the storm geographic extent indicates cyclone size also decreases above a threshold value of bulk environmental temperature (and water vapor). Decrease in storm size is concomitant with an increase in the convective fraction of precipitation and a shift in the vertical distribution of latent heating. The results indicate the existence of at least two regimes for ETC development, each of which exhibit significantly different distributions of PV due to differences in timing and location of convective heating.

The impacts of a biofuel use on the gas turbine operating performance

The use of Pure Plant Oil (PPO) as a fuel blend in a power plant is mandatory as stipulated in the Ministerial Decree of Energy and Mineral Resource of the Republic of Indonesia. However, the implementation of PPO used in power generation has many obstacles due to a lack of information concerning the impacts of PPO used in the operating performance of the power generation engine. In this study, the effect of PPO as a blended fuel with High-Speed Diesel (HSD) was studied by using the gas turbine with a capacity of 18 MW. The PPO was blended based on volume with a ratio of 0%, 5%, 10% and 20%. As the results, it is shown that the use of PPO with a blend ratio of 20% is the maximum fuel blend ratio according to the threshold value of a flue gas temperature and a vibration velocity in the gas turbine.

Temperature-Dependent Development of Oligota flavicornis (Coleoptera: Staphylinidae) Preying on Tetranychus cinnabarinus (Acarina: Tetranychidae).

The effect of nine constant temperatures on developmental time of Oligota flavicornis (Boisduval and Lacordaire) preying on Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae) eggs was determined under laboratory conditions of 75 ± 5% RH and a 16:8 (L:D) h photoperiod. O. flavicornis survival rates were highest between 18 and 30°C, although O. flavicornis eggs developed successfully to adults at 12-32°C, and the developmental durations to adult at the seven temperatures (12, 15, 18, 20, 25, 30, and 32°C) were 114.41, 51.66, 33.45, 23.21, 13.43, 11.54, and 17.18 d, respectively. Two linear and seven nonlinear models (Logan-6 and Logan-10, Taylor, Lactin-1 and Lactin-2, and Brière-1 and Brière-2) were fit to the developmental rates of the immature predatory stages to estimate the thermal constant (K) and critical temperatures. The lower temperature threshold (T0) and K for the immature stages using the common linear model were 9.96°C and 225.73 degree-days and Ikemoto-Takai linear model were 11.01°C and 167.14 degree-days, respectively. The upper temperature threshold values estimated by the Logan-6 and Lactin-1 models were both 34.86°C. The T0 values estimated by the Brière-1 and Brière-2 models were 10.67 and 9.32°C for all immature stages, respectively, and the estimated optimal temperature according to the Brière-2 model was 29.59°C. Therefore, the two linear models and Brière-2 model estimates approximated the actual relationship between the temperature and developmental rate of immature O. flavicornis.