Temperature dependence of mechanical properties and damage evolution of hot dry rocks under rapid cooling

Understanding the differences in mechanical properties and damage characteristics of granitoid under high temperatures is crucial for exploring deep geothermal resources.This study analyzes the evolution of the acoustic emission(AE)characteristics and mechanical parameters of granodiorite and granite after heating and water cooling by uniaxial compression and variable-angle shear tests under different temperature gradients.We identify their changes in mesostructure and mineral composition with electron probe microanalysis and scanning electron microscopy.Results show that these two hot dry rocks have similar diagenetic minerals and microstructure,but show significantly different mechanical and acoustic characteristics,and even opposing evolution trends in a certain temperature range.At the temperatures ranging from 100℃to 500℃,the compressive and shear mechanical properties of granodiorite switch repeatedly between weakening and strengthening,and those of granite show a continuous weakening trend.At 600℃,both rocks exhibit a deterioration of mechanical properties.The damage mode of granite is characterized by initiating at low stress,exponential evolutionary activity,and intensified energy release.In contrast,granodiorite exhibits the characteristics of initiating at high stress,volatile evolutionary activity,and intermittent energy release,due to its more stable microstructure and fewer thermal defects compared to granite.As the temperature increases,the initiation and propagation of secondary cracks in granodiorite are suppressed to a certain extent,and the seismicity and brittleness are enhanced.The subtle differences in grain size,microscopic heterogeneity,and mineral composition of the two hot dry rocks determine the different acoustic-mechanical characteristics under heating and cooling,and the evolution trends with temperature.These findings are of great significance for the scientific and efficient construction of rock mass engineering by rationally utilizing different rock strata properties.

Drying Temperature Effect on Kernel Damage and Viability of Maize Dried in a Solar Biomass Hybrid Dryer

Though several maize varieties have been developed and introduced over the years in Ghana, farmers still face challenges of access to quality seed maize. Among the major constraint is lack of proper drying systems to guarantee quality of seed produced. As in most parts of Africa, drying of maize in the open, on bare ground along shoulders of roads is still a common practice in Ghana. In this study, a 5-tonne capacity hybrid solar biomass dryer was developed for drying maize for seed and food/feed in Ghana. Effect of air temperature in the dryer on the physiological quality and germination of maize kernels was investigated. Maize grains were dried in the open sun simulating farmers practice and using the dryer at 4 varying levels (L1, L2, L3 and L4) with corresponding heights (0.6 m, 1.2 m, 1.8 m and 2.4 m, respectively) from the ground. Harvested maize at 22.8% moisture content was dried at the varying levels until reaching the final desired moisture content of 12.8% ± 0.2% (wb). Results showed that, air temperatures in the dryer increased in accordance with height with lowest mean temperature of 44.4&degC ± 4.6&degC recorded at L1 and mean maximum of 52.8&degC ± 5.4&degC at L4. Drying temperatures recorded at L1 - L3 and ambient had no significant effect (p < 0.05) on kernel damage and viability. Drying conditions at L1-L3 were considered optimum (<50&degC) for kernel drying compared to the topmost tray, L4. Kernel stress crack index (multiple and checked) was therefore reduced on average by 14% while kernel germination increased by 33%. This satisfies the dryer’s potential to be used for commercial drying of maize grains for seed production for smallholder farmers in Ghana.

Influence of High Temperature Stress on Net Photosynthesis, Dry Matter Partitioning and Rice Grain Yield at Flowering and Grain Filling Stages

Climate change is recognized to increase the frequency and severity of extreme temperature events. At flowering and grain filling stages, risk of high temperature stress （HTS） on rice might increase, and lead to declining grain yields. A regulated cabinet experiment was carried out to investigate effects of high temperature stress on rice growth at flowering and grain- filling stages. Results showed that no obvious decrease pattern in net photosynthesis appeared along with the temperature rising, but the dry matter allocation in leaf, leaf sheath, culm, and panicle all changed. Dry weight of panicle decreased, and ratio of straw to total above ground crop dry weight increased 6-34% from CK, which might have great effects on carbon cycling and green house gas emission. Grain yield decreased significantly across all treatments on average from 15 to 73%. Occurrence of HTS at flowering stage showed more serious influence on grain yield than at grain filling stage. High temperature stress showed negative effects on harvest index. It might be helpful to provide valuable information for crop simulation models to capture the effects of high temperature stress on rice, and evaluate the high temperature risk.

STEAMING-HIGH TEMPERATURE DRYING OF LARCH LUMBER

A scries of drying tests on Larch Lumber and a theoretical analysis led to the following conclusions:1. Steaming prctrcatmcnt is a very powerful means to decrease defects induced by the drying process and increases the drying velocity of the lumber.2. The steaming-high-temperature drying schedule had resulted in fast drying and good quality of the dried lumber.

Insight into the effect of gel drying temperature on the structure and desulfurization performance of ZnO/SiO_(2)adsorbents

A series of ZnO/SiO_(2) adsorbents were prepared by a sol-gel method using tetraethyl orthosilicate,ethylene glycol(EG)and nitrates as precursors.The effect of gel drying temperature on the structure and desulfurization performance of the adsorbents were investigated in detail.It is found that the low drying temperature led to a weak interaction among EG,Si AOH/H_(2)O and the nitrates in the gel system,which caused the oxidation of EG by NO3-and formed zinc glyoxylate complex during the gel calcination process,whereas this oxidation process also occurred at a high drying temperature during the gel drying process.The formed zinc glyoxylate complex promoted the generation of monodentate carbonate on the surface of Zn O,which resulted in the inferior desulfurization performance of adsorbents despite they have smaller Zn O nanoparticles.The gel dried at 120°C formed the hydrogen bonds between EG and Si AOH/H_(2)O and a strong interaction between zinc oxo-clusters and NO3-was also found in the gel system,which avoided the oxidation of EG by NO3-during the preparation process and the Zn O nanoparticles with sizes of 6 nm were formed by a combustion method.The adsorbent affords a highest sulfur capacity of 104.9 mg·g^(-1) in this case.In addition,the gel drying temperature has a significant influence on the textural properties of the adsorbents except their surface area.

Empirical Model to Calculate the Thermodynamic Wet-Bulb Temperature of Moist Air

An equation model for calculating the adiabatic temperature of the wet-bulb thermometer has been obtained empirical fit through a meteorological database, specificly a trough relative humidity and air temperature. A comparison of the results of calculations with the use of this equation and from meteorological database was made. The model deducted of the comparison is valid for a dry bulb temperature range of 3°C to 35°C and for relative humidity percentage in a range of 7% to 97%. Normalized errors are less than 5.5%. It means a maximum variation of 0.55°C from data. However, this variation from error represents only 3.6% of the data sample. The equation model was satisfactory.

Unravelling Effects of Temperature and Soil Moisture Stress Response on Development of Dry Root Rot [<i>Rhizoctonia bataticola</i>(Taub.)] Butler in Chickpea

Erratic rainfalls and rise in temperature have become more frequent under the changing scenario of climate particularly in semiarid tropics. As a consequence of it, a drastic shift of chickpea diseases have been recorded throughout the major chickpea growing regions in India and elsewhere. Dry root rot (DRR) caused by Rhizoctonia bataticola (Taub.) Butler [Pycnidial stage: Macrophomina phaseolina (Tassi) Goid] was found as a potentially emerging constraint to chickpea production than wilt (Fusarium oxysporum f. sp. ciceris). Increasing incidence of DRR indicate strong influence of climate change variables such as temperature and moisture on the development of disease. The present study therefore was conducted to quantify the role of temperature and soil moisture associated with infection, colonization and development of DRR under controlled environment. The DRR incidence was significantly affected by high temperature and soil moisture deficit. Out of five temperature regimes (15?C, 20?C, 25?C, 30?C and 35?C) and four moisture levels (40%, 60%, 80% and 100%), a combination of high temperature (35?C) and soil moisture content (60%) predisposes chickpea to DRR. The study clearly demonstrates that high temperature coupled with soil moisture deficit is the climate change variables predisposing chickpea to R. bataticola infection, colonization and development.

Numerical Simulation for Hot Dry Rock Geothermal Well Temperature Field

Study on temperature distribution simulation during cementing of hot dry rock (HDR) geothermal well is rare. It has important guiding significance to simulate the construction process of temperature distribution of hot dry rock on site construction. Based on numerical simulation of HDR considering heat-fluid-solid coupling, the influence of temperature distribution on well cementing is analyzed when the drilling fluid cycles and reaches stable state, respectively, and when the cement slurry is injected during the cementing process. It is found that the seepage at the well bottom accelerates the flow velocity of wellbore;the stable temperature change is less than the cyclic temperature change;and the upper and lower temperature variation of the stratum is greater when the cement slurry is injected. Therefore, as to cement retarder involved, the influence of temperature variation on concretion should be considered during cementing of the hot dry rock geothermal well.

An Experimental Investigation of Temperature Distribution in Different Urban Locations in Aswan, Egypt of Hot and Dry Climate

This paper describes the measurements and analysis of an experimental campaign performed in different urban street in Aswan, Egypt. The present study is focused on the experimental investigation of thermal characteristics during summer 2012 of five different regions location (building on Nile river shore, building in front of a mountain, building under high power transmission line, two building opposite other in resident region, finally ship in Nile river) aiming at the investigation of the impact of urban location on the potential of natural and hybrid ventilation under hot weather conditions. The temporal and spatial distribution of air and surface temperatures is examined. Emphasis was given on the vertical distribution of air and surface temperatures. The results showed that the measured surface temperature across the street was the highest value than the air and wall temperature where temperature difference between street and air temperature could reach 35℃ and this favored the overheating of lower air levels. Buoyancy generated mainly from asphalt-street heating resulted in the development of the predominant recirculation inside the street canyon. The results also show that air temperature for two building opposite other has a lower value followed by building on Nile river shore followed by building at front of mountain.

The Influence of Drying Temperature and Extraction Methods on a-Mangostin in Mangosteen Pericarp

The effects of drying temperature and extraction methods on α-mangostin content in mangosteen pericarp （Garcinia mangostana L.） powder were investigated. In the first part of experiment suitable drying temperature for retention α-mangostin content was determined. Three levels of drying temperatures （55, 65 and 75 ℃） were used in this study. The drying rates were increased with drying temperature. Room temperature extraction method was performed to investigate the effect of drying temperature on retention α-mangostin content in mangosteen pericarp. The α-mangostin content extracted at three different drying temperatures （55, 65 and 75 ℃） was 35.98 ± 0.49%, 40.32 ± 0.24%, and 37.79±0.34% w/w, respectively. The results showed that the suitable temperature for drying mangosteen pericarp was 65 ℃ that gave the highest of α-mangostin content. The second part of experiment was the comparison between extraction methods, such as shaking water bath extraction （SWE）, soxhlet extraction （SE） and microwave-assisted extraction （MAE）. The results show that MAE gave the highest extraction rate and α-mangostin content as compare to SWE and SE. The α-mangostin content extraction from SWE, SE and MAE are 45.83 ± 0.02, 34.82± 0.17 and 49.79 ± 0.15% w/w of crude extract, respectively.

Temperature and Humidity Control System Identification Based on Neural Network in Heating and Drying System

Artificial neural network has unique advantages for massively parallel processing, distributed storage capacity and self-learning ability. The paper mainly constructs neural network identifier and neural network controller for system identification and control on temperature and hmnidity of heating and drying system of materials. And the paper introduces the structure and principles of neural network, and focuses on analyzing learning algorithm, training algorithm and limitation of the most widely applied multi-layer feed-forward neural network （ BP network） , based on which the paper proposes introducing momentum to improve BP network.

Transporting Mammalian Cells at Ambient Temperature:A Viable Alternative to Dry Ice

The most common method of shipping cells between institutes and companies is sending them frozen, usually treated with anti-freeze solution (most commonly DMSO because it is less toxic than many alternatives), and then packaging them in dry ice for shipment. However many countries place restrictions on dry ice shipments. An alternative to shipping frozen cell vials is to send flasks of growing cells in media. This also has problems because cells in media have limited viability and the flasks can leak. Here we report on an alternative method for shipping viable cells at ambient temperature without dry ice or in media filled flasks. In this study we report on the development and properties of HemSol?. This is an inexpensive, eco-friendly and protects cell integrity at ambient temperature while maintaining viability. We have previously shown that HemSol? protects platelet and RBC function in cold storage and circulating tumor cells up to 6 days. Therefore we wanted to know if HemSol? could also be used to transport live cells. Since HemSol? is a liquid, we experimented with encasing the cells with HemSol? and gelatin so as to prevent dry ice shipment of cells and circumvent the shipping of cells in media. We performed mock shipping experiments where cells were stored in HemSol? gel kept at room temperature on a lab benchtop and cells stored in dry ice was also kept on lab benchtop for up to 2 days. After the mock shipping period, we analyzed cells for their functions. Our results show that cells in HemSol? gel have greater than 95% viability and restored biological functions in 2 hours, whereas, cells shipped in dry ice required more than 24 hours to recover and needed media change to remove the DMSO.

Tribological behaviour of AZ71E alloy at high temperatures

Tribological behaviour of the die-cast AZ71E magnesium alloy was investigated in an applied load range of 10-50 N at high temperatures under dry sliding conditions using a pin-on-disc wear testing machine. The results indicate that the wear rate increases with the increase of applied load and sliding distance, whereas the friction coefficient decreases with the increase of applied load. Scanning electron microscopy and optical microscopy studies on the worn surfaces and sub-surfaces show that the predominant wear mechanism is abrasion at low applied loads. The mild delamination wear accompanying with adhesion wear is the predominant wear mechanism under high applied loads at 150 ℃, whereas the severe delamination and melting wear are the predominant wear mechanisms under high applied load at 200 ℃. An investigation of the microstructure, thermal stability and tensile properties at high temperatures, using the optical microscopy, X-ray diffraction, differential scanning calorimetry, shows that the dominant secondary phase in AZ71E alloy, Al11Ce3, leads to the improvement in the tensile and elongation properties of alloy at high temperatures, which results in the improvement in the anti wear performance.

Changes in Daily Climate Extremes of Observed Temperature and Precipitation in China

Daily precipitation for 1960-2011 and maximum/minimum temperature extremes for 1960-2008 recorded at 549 stations in China are utilized to investigate climate extreme variations.A set of indices is derived and analyzed with a main focus on the trends and variabilities of daily extreme occurrences.Results show significant increases in daily extreme warm temperatures and decreases in daily extreme cold temperatures,defined as the number of days in which daily maximum temperature （Tmax） and daily minimum temperature （Tmin） are greater than the 90th percentile and less than thel0th percentile,respectively.Generally,the trend magnitudes are larger in indices derived from Tmin than those from Tmax.Trends of percentile-based precipitation indices show distinct spatial patterns with increases in heavy precipitation events,defined as the top 95th percentile of daily precipitation,in westem and northeastern China and in the low reaches of the Yangtze River basin region,and slight decreases in other areas.Light precipitation,defined as the tail of the 5th percentile of daily precipitation,however,decreases in most areas.The annual maximum consecutive dry days （CDD） show an increasing trend in southem China and the middle-low reach of the Yellow River basin,while the annual maximum consecutive wet days （CWD） displays a downtrend over most regions except western China.These indices vary significantly with regions and seasons.Overall,occurrences of extreme events in China are more frequent,particularly the night time extreme temperature,and landmasses in China become warmer and wetter.

Influence of temperature on swelling deformation characteristic of compacted GMZ bentonite-sand mixtures

Laboratory swelling deformation tests were carried out on compacted GMZ bentonite and bentonite-sand mixtures with 30%and 50%sand contents at 20,40,60,80 and 90°C with infiltration of distilled water.Influence of temperature,initial dry density,and quartz sand content on the swelling deformation characteristic of compacted bentonite specimens was analyzed.Results indicate that the swelling deformation process is accelerated,and the maximum swelling strain increases with the increase in temperature,while the maximum swelling strain tends to be stable with increasing temperature.In the meantime,the temperature effects depend on both of the sand content and the initial dry density of the specimens,the increases of the maximum swelling strain induced by increasing temperature,are enlarged by increasing sand content or initial dry density.Adding of quartz sand to bentonite not only influences the integrality of bentonite specimen,but also increase the microfissuring in area on quartz sand,which are advantageous to the heat transfer,leading to the increase of swelling deformation capacity of the specimen.The increased dry density relatively increases the bentonite content,so the swelling property is enhanced.However,no change on mineral composition of bentonite was observed when temperature was changed from 20 to 90°C.

Evolution of a Water Pendant Droplet: Effect of Temperature and Relative Humidity

As part of a better understanding of drying liquids within porous materials, measurements from 293 to 343 K of deionized water surface tension in air as a function of relative humidity are exposed. Experimental work was carried out using the pendant drop method coupled with image analysis within an adapted instrumented climatic chamber. Results show that surface tension linearly decreases when relative humidity increases. Although the effect of humidity is less compared to that of the temperature and even less compared to a surfactant impact, it must not be neglected and values have to be mentioned when dealing with water evaporation. Modifying surface tension also affects the pendant drop shape. The drying kinetics of the pendant drop volume and its outer shell are connected to this change of shape. Steam in the air can be assimilated to a wetting agent, hence a surfactant, and can be used in an environmental-friendly way to ease the drying stage. Indeed, the challenge is to limit the risk of cracking and damaging pieces during this crucial step in material processing.

Prospect of HDR geothermal energy exploitation in Yangbajing,Tibet,China,and experimental investigation of granite under high temperature and high pressure

Hot dry rock （HDR） geothermal energy, almost inexhaustible green energy, was first put forward in the 1970s. The development and testing of HDR geothermal energy are well reported in USA, Japan, UK, France and other countries or regions. In this paper, the geological characters of Yangbajing basin were first analyzed, including the continental dynamic environments to form HDR geothermal fields in Tibet, the tectonic characteristics of south slope of Nyainqentanglha and Dangxiong-Yangbajing basin, and the in-situ stresses based on the investigations conducted, and then the site-specific mining scheme of HDR geothermal resources was proposed. For the potential development of HDR geothermal energy, a series of experiments were conducted on large-scale granite samples, 200 mm in diameter and 400 mm in length, at high temperature and high triaxial pressure for cutting fragmentation and borehole stability. For the borehole stability test, a hole of 40 mm in diameter and 400 mm in length was aforehand drilled in the prepared intact granite sample. The results indicate that the cutting velocity obviously increases with temperature when bit pressure is over a certain value, while the unit rock-breaking energy consumption decreases and the rock-breaking efficiency increases with temperature at the triaxial pressure of 100 MPa. The critical temperature and pressure that can result in intensive damage to granite are 400-500℃ and 100-125 MPa, respectively.

The Effect of High Day and Low Night Temperature on Pollen Production, Pollen Germination and Postharvest Quality of Tomatoes

Temperature integration where high day temperatures are compensated by lower night temperatures is one strategy that can be used to reduce energy consumption in greenhouses. Crop tolerance to temperature variation is a prerequisite for using such a strategy. Greenhouse experiments were conducted on tomatoes cvs, Capricia, Mecano and Cederico in order to investigate the effect of different day/night temperature regimes (24/17, 27/14 and 30/11℃) where the same mean temperature was maintained for the production and germination of pollen. In addition, fruit quality as determined by fruit firmness, dry matter content, soluble solids, titratable acids, and pH was examined at harvest and after seven and 14 days of storage. The 30/11℃ treatment significantly increased pollen production and germination compared to the 24/17℃ treatment, while the 27/14℃ treatment was generally in between the other two treatments. Fruits grown at the 27/14℃ treatment were significantly firmer, while fruits grown at 24/17℃ had higher dry matter content, soluble solids, and titratable acids compared to the other treatments. There were significant differences between cultivars with respect to firmness, dry matter, titratable acidity, and pH. The quality of the fruits changed during storage, but the storability of the tomatoes was not affected by preharvest temperature treatments. The overall conclusion was that the 27/14℃ treatment was superior to the other two temperature treatments with respect to the studied parameters.

THE INFLUENCE OF THE DRAWING TEMPERATURE ON PHYSICAL STRUCTURE AND PROPERTIES OF PET FILAMENTS

In this paper the influences of the drawing temperature on physical structures and properties of PET filaments have been studied. The results show that the temperatures of the first-stage drawing will have significant effects on birefringence development of filaments during the second stage drawing, as well as the oriented amorphous filaments change to crystanine-oriented filaments after heat treatment. Increasing temperature of the second-stage drawing can be greatly increasing the crystallinity and decreasing the dry heat shrinkage of the filaments.

Evaluation of the Gas Turbine Inlet Temperature with Relation to the Excess Air

This paper shows the effect of excess air on combustion gas temperature at turbine inlet, and how it determines power and thermal efficiency of a gas turbine at different pressure ratios and excess air. In such a way an analytic Equation that allows calculating the turbine inlet temperature as a function of excess air, pressure ratio and relative humidity is given. Humidity Impact on excess air calculation is also analyzed and presented. Likewise it is demonstrated that dry air calculations determine a higher level for calculations that can be performed on wet air.