Small Amount Of Precipitation Research Articles

Hydrochemical and operational parameters driving carbonate scale kinetics at geothermal facilities in the Bavarian Molasse Basin

The majority of scales observed at geothermal facilities exploring the Malm Aquifer in the Bavarian Molasse Basin are carbonates. They form due to a disruption of the lime–carbonic acid equilibrium during production caused by a reduction of the partial pressure of carbon dioxide due to pressure change and degassing. These scales are found at the pumps, production pipes, filters, heat exchangers, and occasionally in the injection pipes. In this study, scales of all sections of geothermal facilities were taken. The database consists of scale samples from 13 geothermal pumps, 6,000 m production pipe (sample interval 10 - 12 m), 11 heat exchanger revisions, 2 injection pipes, and numerous filter elements. The samples were analyzed by SEM-EDX, XRD, Raman spectroscopy, and acid digestion to assess their chemical and mineralogical composition. From direct gauge measurements at six facilities during pump changes, scale rates were determined along the production pipes. From indirect measurements (multifinger caliper measurements) scale rates are derived for the region below the pump. Hydrochemical analyses from the wellhead were taken from 13 sites to feed the hydrogeochemical models. The calcite scale rates in the production pipes increase from the pump to the wellhead, where they reach 1.5 - 4.1 mumol/(hbox {m}^2,cdot s). Scale rates below the pump reach up to 1.5 mumol/(hbox {m}^2,cdot s). Given the slight change of hydrochemistry on the rise through the production pipe, where < 4 % of dissolved calcium ions precipitate as scale, scale rates cannot be derived from water samples at the wellhead, but require direct gauge measurements. The small amount of precipitation, together with fully turbulent conditions suggests that all measured rates are controlled by the surface-reaction of calcite crystallization following the nomenclature of Appelo and Postma (2004). Two approaches are used for the modeling of the scale rates. The first approach is based on hydrogeochemical modeling with PHREEQC. Scale rates calculated by this method are one order of magnitude higher than the measured ones. The second approach is based on correlations between the measured scale rates at the wellhead at six facilities and identified thermodynamic scale drivers (Delta log (phbox {CO}_2), Delta total pressure, Delta pH, and hbox {SI}_{{calcite}}). The correlations allow linear regressions which are used for the prediction of the scale rate at the wellhead, along the whole production pipe, and below. The modeling results show that scale prediction based on the new regressions that rely on thermodynamic scale drivers works better than existing hydrogeochemical models, already without implementation of kinetic parameters (hbox {CO}_2-stripping and magnesium inhibition).

Catenated Cages Mediated by Enthalpic Reaction Intermediates

Catenated cages are generally considered thermodynamically more stable than their constituent monomeric cages. However, the catenation mechanism is yet to be elucidated; it would require systematic...

On the Origin of Deep Soil Water Infiltration in the Arid Sandy Region of China

Soil water moisture is one of the most important influencing factors in the fragile ecosystems in arid sandy regions, and it serves as a bridge connecting the rainfall and groundwater, two important water sources in arid sandy regions. The hydrological process of an arid sandy region occurs sporadically and is highly non-uniform temporally, making it difficult to monitor and predict. The deep soil recharge (DSR) at a sufficiently deep soil layer (usually greater than 200 cm below ground surface) is an important indicator for groundwater recharge in the arid sandy region, and thus the quantitative determination of DSR is of great significance to the evaluation of water resources and the study of water balance in the arid sandy region. Due to the large amount of evaporation, small amount of precipitation, and the long term of the frozen-soil period in the winter and spring, the monitoring of infiltration and determination of DSR in the arid sandy region become challenging. This study selects the Ulanbuh desert plots in northern China to monitor DSR, precipitation and seasonal frozen soil thickness change, and reaches the following conclusions: Even though the annual precipitation is only 48.2 mm in the arid sandy region, DSR will still occur and replenish groundwater. The daily threshold of precipitation for generating measurable DSR is lower than 4 mm, where the DSR value is defined as the downward flux over a unit area per day hereinafter. DSR continues during the frozen period of the winter and spring seasons, and it is generated from water vapor transport and condensation in the deep sandy layer. Summer rainstorms do no show an obvious correlation with DSR, which is unexpected. This study reveals the characteristics of the dynamic water resources movement and transformation in the arid sandy area in Ulanbuh Desert and can serve as an important guideline for the quantitative assessment of water resources in arid sandy regions.

Thermoelectric properties of Fe1.5TiSb1−Sn and Fe1.5Ti1−Y Sb Heusler alloys

Abstract The effects of Sn and Y doping on thermoelectric properties of a Heusler Fe1.5TiSb semiconductor was studied. Samples of Fe1.5TiSb1−xSnx and Fe1.5Ti1−xYxSb solid solutions (x = 0; 0.05; 0.1) were synthesized by arc and induction melting, annealed at 1073 K, and examined by X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray analysis. All alloys of the solid solutions crystallize in the half Heusler structure (space group F43m), and have dominant phase Fe1.33TiSb with a small amount of precipitates. Measurements of the transport properties revealed that all the alloys are p-type semiconductors. In the parent Fe1.5TiSb, substitution of Sb by Sn results in increasing electrical conductivity σ, whereas substitution of Ti Y decreases σ. Measurements of thermal conductivity κ showed that it decreases with substitution Sb for Sn, as well as with substitution of Ti for Y. The highest zT = 0.14 (at 473 K), was found for the composition Fe1.5TiSb.

Climate, lithology, and tectonics interaction in shaping a hazardous salt karst: A case from the middle–late Miocene (?) evaporite succession of NE Iran

Karst landforms cover a considerable area of the Earth's surface. With increasing population and demand for further land exploitation, the prospect of being affected by karsts has increased dramatically over the past decades. Among karst landforms, salt karsts show higher vulnerability and faster evolution in the human life-span. In Iran, most of salt karst studies have been carried out in the south (mainly Zagros). Contrariwise, the northern and central parts of the country have been rarely studied. This study investigates a salt karst system in the northeastern part of the Central Iran. Field investigation and satellite image analysis of the area revealed a salt karst in the Upper Red Formation (URF) comprising elements of a mature karstic system including dolines, ponors, caves, shafts, valleys, poljes, springs, and streams. Tectonics by creating open fractures in impermeable salts provided conduits for fluid transport and development of the karst. Since salts are highly soluble and disappear very soon, arid climate in the studied area led to the preservation of the salt karst. Although the area is a cold desert with small amounts of precipitation, it is hydrologically active. This is ascribed to the increased water efficiency by the karst system that immediately funnels the runoffs into the ground and prevents from evaporation. Water efficiency is amplified by an impermeable substrate of the karst and timing of the precipitation. The studied karst partly underlies the Tehran–Mashhad railway which endangers the infrastructure, and can cause failure and casualties. Since the salt bearing URF extends throughout large parts of Central Iran, this study suggests comprehensive geomorphological, hydrogeological, and geophysical studies of this formation for providing hazard maps.

Atmospheric Precipitation Within the Selenga River Basin and Large-Scale Atmospheric Circulation Over Eurasia in July

Data from the Global Precipitation Climatology Centre (GPCC) were used in investigating long-term variability of anomalies of the total amount of atmospheric precipitation within the Selenga river basin in July. We identified several long periods (four years and longer) with negative precipitation anomalies: 1935–1939, 1955–1958, 1977–1981, 2007–2011, and 2013–2017. The last period is characterized by the smallest precipitation amount. Day-to-day variations in total precipitation were also analyzed for each July from 1982 to 2016. The analysis revealed a tendency to a decrease of the number of days with a large precipitation amount and to an increase of dry periods. Based on ECMWF Era Interim data, we examined the features in the atmospheric blocking Europe, Siberia and the Far East for periods with large and small precipitation amounts within the Selenga river basin. To identify the blocking in the atmosphere used the southern gradient of the geopotential. It was shown that in periods with large precipitation amounts blockings occurred most frequently over Eastern Siberia and more rarely over Europe and the Far East (especially if they were accompanied by blocking over Western Siberia). Atmospheric precipitation within the Selenga basin is associated not only with blocking but also with the position of the jet stream and with dynamic blocking formation schemes. The significance of these factors has been demonstrated in a number of specific situations of the atmospheric circulation in years with large and small precipitation amounts within the Selenga basin. Long-term transformations of these characteristics caused by climate change and the general atmospheric circulation can lead to a disturbance of the correlations between blocking and precipitation amounts within the river basin. In all likelihood, the correlation of blocking with precipitation regimes, rather than with precipitation in the region, will be more rigid. A functional dependence of the Selenga flow on climate change appears to be determined by the position of the monsoon front and by the wave properties of atmospheric flows in midlatitudes.

Индикаторные признаки адаптации субтропических древесных растений на основе комплексных исследований

For the Lower Volga region with difficult soil and climatic conditions, forecasts bear an increase in the length of the growing season, an increase in heat, and a softer winters. This indicates the need for studies of subtropical plants for an objective assessment of the identification of mechanisms for their adaptation and prospects for creating protective forest plantations in sparsely wooded regions. Theoretical and practical interest for the Volgograd region is a valuable fruit, medicinal, forest reclamation and ornamental shrub (unabi) plant Zizyphus jujuba Mill. (family Rhamnaceae). The purpose of the research is to study the ecological and physiological features of subtropical woody plants of Zizyphus jujuba and to identify indicator signs of their adaptation in the Volgograd region. The objects of research were the varietal plants of the unabi (Ta-yang-zao, Southerner - large-fruited, Druzhba, Phenicia - medium-fruited, Sochi, Temryuk - small-fruited). They are tested in the Volgograd region for the first time, obtained from the FSBI (city of Sochi) and are cultivated in FSBI FNTS Agroecology RAS (Volgograd region, Russia). The soils of the experimental plot (50 ° 4´-50 ° 5´N and 45 ° 22´-45 ° 23´E) are characterized by a low humus content (from 0.57 to 1.15%). It was revealed that the study area (Volgograd region) is characterized by a small amount of precipitation, low temperatures in winter, high temperatures in summer, droughts of high and medium intensity. The amplitude of the absolute maxima and minima varies from seventy-eight (dry steppe) to ninety degrees Celsius (semi-desert). It has been established that the agroclimatic resources of natural distribution areas differ from the introduction points of Zizyphus jujuba Mill. to culture. Different levels of morphological variability, as well as water availability, lead to a change in the ability to expend and retain water, to a lack of moisture in the leaves of Z.jujuba. The insignificant effect of drought on the state of the aboveground plant organs during the arid periods was observed in medium-sized and large-fruited varieties. Young, non-lignified shoots are damaged (at an air temperature of about 40 ° C and a decrease in air humidity of up to 10%). A decrease in leaf turgor was observed with water deficit indicators of 28.3-35.8%. Water deficiency decreases by 6-10% with increasing age, which is due to increased adaptation and regulation of water balance. According to the indicators of the relative electrolyte yield, groups were determined according to the degree of drought resistance: low - Southerner, Ta-Yan-Zao (4.23-4.71), medium - Finik, Friendship (3.10-3.61) and high - Temryuk, Sochi (1.64-1.99). Ecological tolerance of various organisms to low temperatures is quite specific. Evaluation of different varieties of Zizyphus jujuba under light-brown soils showed that the adaptation of plants to low temperatures increases with increasing age. In small varieties with an increase in age, the damage is minor. Based on the vegetation experience, the limits of ecological tolerance of small-fruited forms of Zizyphus jujuba to chloride salinity were established, which makes it possible to predict their successful cultivation on soils with a chlorine ion content of 0.1%. Thus, complex ecological and physiological studies of the adaptive capacity of subtropical plants Zizyphus jujuba revealed indicator signs that allow to evaluate and predict the degree of adaptation depending on the variety and the response to stress factors specific to the conditions of the Lower Volga region.

Effect of Micro-Scale Er on the Microstructure and Fluidity of ZL205A Alloy.

The effect of Er addition on the fluidity and microstructure transformation of the as-cast and T5 heat-treated ZL205A alloys was investigated by optical microscope (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). The fluidity of the liquid metal after adding Er was tested and the fracture characteristics of the material were analyzed. The results indicated that Er was mainly dissolved into an α–Al matrix near the grain boundaries (GBs). It is easily segregated and enriched in the intersection of the GBs or the interface between the α and θ phase, which caused the intermetallic compounds to be distributed along the GBs to the neck and to fuse. Er could also inhibit the diffusion of Cu atoms in the process of solid solution, so that increased the residual eutectic structures in the crystal, while accelerating the precipitation progress of the Guinier–Preston (GP) zone and θ’ phase and increasing precipitation of the θ phase. A small amount of precipitation of θ phase and micro-scale Er (0.1–0.5 wt %) can significantly increase the fluidity and reduce the casting defects, which can effectively improve the castability of the ZL205A alloy. The interface between the (Al8Cu4Er) phase and matrix is the main area of microcracks, through analyzing the fracture morphology.

THE USE OF THE ISOTOPIC METHOD IN THE ASSESSMENT OF THE URBANIZATION OF ATMOSPHERIC PRECIPITATION IN MOSCOW

The study was carried out on the basis of all the individual samples (101 cases) of precipitation for 2014, sampled at the Meteorological Observatory of Moscow State University. The concentrations of the main anions and cations, the total mineralization and δ18O values were determined. 12 cases of relatively high mineralization of precipitation were recorded. Average weighted mineralization values ranged from 12.0 to 67.7 mg/L, specific values of mineralization varied from 3.2 to 229.0 mg/L. Chlorine prevails among anions, calcium prevails among cations. The used isotope data analysis and backward trajectories of air masses showed the hydro-chemical composition of precipitation in Moscow not to be linked to the origin of air masses. This indicates to the predominantly urban origin of pollutants in precipitation. In general, in 2014 precipitation were significantly more mineralized than in previous years of observations, due to the climatic conditions of a particular year - small amount of precipitation and number of days with precipitation. This has led to the accumulation of pollutants in the atmosphere and the poor washout of pollutants.

Formation of erosion resistance of gray forest soils in the conditions of Carpathian region

Aim. To study the impact of perennial grasses mixtures on the formation of erosion resistance of gray forest soils of different degradation degree and their unmodifi ed analogues in conditions of long-term permanent experiment. Methods. Field, laboratory, assessment and comparison. Results. It was established that lupine- cereal grass mixtures increased erosion resistance of slope soils considerably within fi fteen years. The sum of soil structural aggregates was improved from satisfactory into good category. There were positive changes in the number of water-resistant aggregates as well. The studies confi rmed a positive impact of legume-grasses on the density and porosity of soil. Soil density was the lowest when the slope was laid down in perennial lupine and its mixture with cereal grasses. The intensifi cation of soil erosion and the approximation of the illuvial horizon level to the surface resulted in the compaction of upper soil layers to 1.29–1.44 g/cc. General porosity of soil correlated with its density which did not exceed optimal values in poorly eroded soils in upper layers. The studies proved the impact of the ways of laying down the slope in grass and the level of soil degradation on its humidity and water permeability. In the experiment conditions, the increase in soil degradation led to the decrease in its moisture. The decrease in the content of humidity in crop fi eld took place at the expense of higher intensity of the growth and water consumption of lupine-cereal grasses in comparison with natural mixed herbs, especially in the periods with a small amount of precipitation. The difference in the upper soil layers was in the range of 0.2–0.5 %. It was established that the highest values of soil water permeability were formed on lupine-cereal grass mixtures in all the variants of degraded soils. Conclusions. Laying down slope lands in perennial lupine in combination with cereal grasses promotes the formation of their higher resistance to erosion processes and restoration of fertility. Perennial legume-cereal mixtures ensure the improvement of structural-aggregate state, total density and porosity of soil, enhance its water supply and water permeability.

КОМПЛЕКСНЫЙ ПОДХОД В СОЗДАНИИ УСТОЙЧИВЫХ К ПАРШЕ ФОРМ ЯБЛОНИ: ФИТОПАТОЛОГИЧЕСКОЕ ТЕСТИРОВАНИЕ И МАРКЕР-ОПОСРЕДОВАННЫЙ ОТБОР

The creation of highly scab-resistant apple genotypes increases the profitability and environmental friendliness of the production of this fruit crop. Early stage evaluation of the resistance using phytopathological testing and DNA markers allows to accelerate the process of breeding for this trait allows the use. The purpose of the study was to comprehensively assess resistance to the causative agent of scab of hybrid seedlings of apple obtained from crossing susceptible (Rennet Simirenko) and resistant (Modi) cultivars for the Rvi6 gene, using infectious background and marker assisted selection. A phytopathological analysis of 207 hybrid apple seedlings against the natural background of apple scab pathogen revealed 117 (56%) plants without scab lesions (0 points). The remaining seedlings had lesions of varying degrees. DNA marker analysis of the Rvi6 gene allowed identification of 105 plants (51%) with the Rvi6rvi6 genotype and 102 (49%) – rvi6rvi6 , which is close to a theoretical segregation ratio 1:1 in the crosses of this type. Comparison of the results of infectious evaluation and DNA-marker analysis showed 98% coincidence of the presence of the resistance gene with no lesions. In general, the complex use of the phenotypic and molecular markers evaluation of the hybrid family for resistance to Venturia inaequalis (Cooke) G. Winter shows a high degree of agreement between the results of the methods. However, the discrepancy between the qualitative classes of reactions to infection and the results of molecular genetic analysis indicates an insufficient strength of the natural infectious background of the study year. The low efficiency of the development of the disease was due to the unfavorable weather and climatic conditions at the beginning of the vegetative period and the formation of infection, which were expressed in a higher average monthly temperature and a small amount of precipitation compared to the norm. Our results suggest an advantage, a comprehensive assessment of resistance to the scab pathogen using an infectious background and marker-assisted selection for the Vf gene ( Rvi6 ) in which the first stage involves the selection of resistant samples against a natural infectious background, followed by confirmation of the presence of the desired gene using a DNA marker analysis.

Influence of Cr on microstructure and elastocaloric effect in Ni–Mn–In–Co–Cr polycrystalline alloys

Ni–Mn-based metamagnetic shape memory alloys have been proposed as potential elastocaloric refrigerants. The intrinsic brittleness of the alloys has limited their cooling application. Introducing a soft second phase is an effective way to reduce the brittleness. From the viewpoint of application, the effect of second phase on elastocaloric effect should be illustrated. In this paper, we have investigated the microstructure, martensitic transformation and elastocaloric effect of Ni45Mn37-xIn13Co5Crx (x=0,1 and 2) polycrystalline alloys. Single-phase and precipitates-containing microstructures are obtained for the undoped and doped alloys, respectively. The precipitates in Cr-doped alloys enhances the fracture strength but significantly hinders the martensitic transformation. Balancing the fracture strength and martensitic transformation, the Ni45Mn36In13Co5Cr alloy with small amount of precipitates along grain boundaries exhibits large cooling effects of 4–6 K in the temperature range of 317–353 K.

Comparison of precipitation collectors used in isotope hydrology

Many hydrologic studies require data on the oxygen and hydrogen stable isotope composition (δ18O, δ2H) of precipitation and various collector designs have been suggested for gathering corresponding samples. Yet, it is crucial that these collectors, also known as totalizers, prevent evaporation and associated isotope fractionation. Surprisingly, we were unable to find a comprehensive collector intercomparison in the literature, and much less one that addressed hot and arid conditions.In this study, we tested six different collector designs over a period of 32 days. They were filled to 20% of their total volume with water of known isotope composition and placed in a modified laboratory drying oven with a low relative humidity (5%) and a diurnal temperature change of 26 to 45 °C. Evaporative mass losses were determined gravimetrically daily while samples for isotope analyses were collected every four days.The classic Oil collector, featuring a layer of paraffin oil to prevent evaporation, showed the smallest mass losses and no detectable isotope shift. The Tube-dip-in-water collector with pressure equilibration tube also performed well, although we noted somewhat larger mass losses and isotope shifts. The latter accounted for 0.28‰ (Δδ18O) and 0.9‰ (Δδ2H) after 32 days, which is significant, but in view of the extreme conditions, these changes should be still acceptable for most studies. The remaining collectors (Ball-in-funnel, Floating balls, and Float based) all failed.Under the prevailing conditions, the Tube-dip-in-water collector with pressure equilibration tube seems to represent a good, oil- and thus contamination-free compromise. Nonetheless, also in this system small precipitation amounts are problematic. This may necessitate modifications of the standard design in terms of funnel diameter and bottle geometry. We strongly advise researchers to conduct own tests with their intended collector before field deployment.

Tackling Air Pollution in Krakow

Data used in order to determine the level of pollutants present in the air in Krakow came from three air quality monitoring stations located in Bulwarowa street, Bujaka street and Krasińskiego avenue. Based on these data, an analysis was performed concerning air quality in Krakow in 2010-2016. Also, a correlation analysis was performed to investigate the relation between air quality parameters and meteorological parameters, such as: wind, precipitation, temperature. An analysis of the results obtained showed that two factors are critical for the variability of air pollution in Krakow. The first of them is low-stack emissions from coal stoves and boilers. The other factor is the type of atmospheric circulation. It has been determined that the worst air quality occurs in the heating season as the prevailing circulation is anticyclonic (high-pressure) characterised by low temperature, lack or small amount of precipitation, weak wind and thermal inversion. The paper presents preventive measures aimed at reducing the amount of pollutants in Krakow. It has been found that in order to reduce the level of air pollution in Krakow, especially in the heating season, it is necessary to intensify operations aimed at eliminating coal and wood stoves and boilers.

Global Warming Leading to Phenological Responses in the Process of Urbanization, South Korea

Current studies are either region-limited, sole-species, or have short researching periods; so, studies about various species are necessary throughout South Korea. In this study, trends of changes in the budding and flowering dates of spring plants by climate factors served to explore the process of urbanization. Four common species, such as Forsythia koreana (forsythia), Rhododendron mucronulatum (azalea), Prunus yedoensis (Yoshino cherry) and Prunus mume (Japanese apricot), are examined during the period from 1973 to 2008 due to the limitation of recent datasets. Budding of forsythia, azalea, Yoshino cherry and the flowering of Japanese apricot are defined as Type I (inland, of reverse letter ‘L’) and flowering of forsythia, azalea and Yoshino cherry were grouped as Type II (inland and south coastline). Prunus mume budding was different from others, so it was defined as Type III (subtropical climate). The inland phonological response is relatively cold and dry and areas are affected by the Siberian high atmospheric pressure. On the other hand, the south and east coastlines are humid and warm areas even in the winter season due to the southeastern wind. There were advancements for 3.1 days of forsythia, 5.5 days of azalea, 6.5 days of Yoshino cherry and 18.6 days of Japanese apricot during the research period. The greatest changes occurred with respect to the minimum temperature in January and the maximum temperature in February, while the precipitation change was not significant. However, in Type II, the precipitation significantly impacted plant flowering events. Precipitation was the lowest in early spring in South Korea and especially the flowering of plants was impacted by the small amount of precipitation in this region. Additionally, if precipitation after budding was over 1 mm for forsythia and azalea, 2 mm for Yoshino cherry and 7 mm for apricot, flowering occurred in over 80% of the region. South Korea is characterized as having a small amount of land and a high population density in cities. As such, it encounters strong influences due to global warming, as well as urbanization. Seven metropolitan cities and Suwon have populations over 1 million and showed more remarkable phenological events and changes of climate factors than the other regions. Especially in the case of shrubs, the phenological events were delayed in urban areas during this research. In conclusion, climate change, as well as urbanization, serve as strong factors leading to phonological and regional events in the ecosystem.

An analysis of the performance of RCMs in simulating current climate over western Canada

ABSTRACTThe performance of eight National Center for Environmental Prediction (NCEP2) reanalysis‐driven regional climate models (RCMs), seven from the North American Regional Climate Change Program (NARCCAP) and one from the Coordinated Regional Downscaling Experiment (CORDEX), in simulating the 1980–2004 climate of western Canada was assessed at a number of spatial and temporal scales. Results indicated that the RCMs were more successful at capturing the seasonal spatial distribution of mean temperature than precipitation and that inaccuracies in the spatial distribution of the summer climate moisture index were likely due to the errors in precipitation distribution and amount. All RCMs performed less well in simulating summer precipitation, most likely due to continued problems with the simulation of convective precipitation.At the grid box scale, quantile–quantile (q–q) plots for temperature indicated that all RCMs showed very similar distributions to observed but with warm or cold biases, and errors in the simulation of a number of temperature‐based extremes indices were related to these biases. For precipitation, q–q plots indicated that most RCMs overestimated precipitation totals, and while tending to follow the observed quantiles at smaller precipitation amounts, they diverged at larger precipitation totals. Performance in simulating the precipitation‐based extremes indices depended largely on whether or not a RCM over‐ or under‐estimated precipitation totals – with those RCMs simulating too much precipitation underestimating the number of consecutive dry days and dry day persistence, and vice versa.Despite improvements in RCM resolution and parameterisation schemes, this work indicates that the simulation of precipitation in particular is still problematic in western Canada. This implies that scenarios of climate change constructed from RCM output require some form of bias correction to be of most use in impacts studies.

Recovery of Ductility in Ultrafine-Grained Low-Carbon Steel Processed Through Equal-Channel Angular Pressing Followed by Cold Rolling and Flash Annealing

The low-carbon steel workpieces are deformed by equal-channel angular pressing at 293 K (20 °C) up to an equivalent strain of ~12 using route Bc, which results in the bulk ultrafine-grained (UFG) structure with high dislocation density and partial dissolution of cementite. The yield strength (YS) is enhanced from 208 (as-received) to 872 MPa and the tensile strength is increased from 362 to 996 MPa, but the material loses total elongation (TE) from 36.2 to 2.9 pct. Cold rolling of equal-channel angular pressed steel produces the refined structure of grain size 0.11 μm. The YS increases further to 924 MPa with a marginal gain in ductility due to the reappearance of the γ fiber component. Flash annealing the samples, which were equal-channel angular pressed followed by cold rolling, at 873 K (600 °C) results in 27 pct of micron-sized (9 µm) ferrite grains in submicron-sized (<1 µm) matrix with a reduced defect density and small amount of precipitation of cementite. TE increases from 2.9 to 23.3 pct. The material retains a YS of 484 MPa and tensile strength of 517 MPa, which are higher than those of the as-received material. The UFG grains are failed by cleavage, but the micron-sized grains display ductile fracture. The ductility of the flash-annealed material is recovered significantly due to bimodal grain size distribution in ferrite and the development of a good amount of γ fiber texture components. The major contribution toward recovery of ductility comes from the bimodal grain size distribution in ferrite rather the precipitation of cementite.

In a 21-2n deformed stainless steel influence of recovery temperature

We present the influence high heat treatment temperature of a nitrogen austenitic stainless steel, deform by cold compression, in 10 different percentages. The steel contains high chromium (19.25 %), nickel (1.5 %) and nitrogen (0.2 %). The typical applications for this alloy are automobile parts and special valves for his excellent mechanical properties and corrosion resistance. Produced by hot rolling, they were subjected homogenized treatment at 975 °C for 45 minutes. Subsequently, deformed, by cold compression. We get ten different deformations, from 3 % to 22 %. These samples then to a heat treatment at 750 °C for one, 2 and 4 hours respectively. To observe the microstructure all samples were metallographic study and measured also their Rockwell C hardness. The initial sample has an austenitic matrix with a small amount of precipitates with a 42 RC average hardness. The homogenized sample had a 39 RC hardness. The deformed samples increased their hardness with a maximum of 49 RC. The samples with the treatment, showed a lower hardness with longer time with high dispersion. The decreased of hardness is due to the elimination of residual stresses and precipitates increasing size.

Effects of Precipitate Element Addition on Microstructure and Magnetic Properties in Magnetostrictive Fe83Ga17alloy

The <100> oriented <TEX>$Fe_{83}Ga_{17}$</TEX> alloys with various contents of NbC or B were prepared by directionally solidification method at the growth rate of <TEX>$720mm{\cdot}h^{-1}$</TEX>. With a small amount of precipitates, the columnar grains grew with cellular mode during directional solidification process, while like-dendrite mode of grains growth was observed in the alloys with higher contents of 0.5 at% due to the dragging effect of precipitates on the boundaries. The NbC precipitates disperse both inside grains and along the boundaries of <TEX>$Fe_{83}Ga_{17}$</TEX> alloys with NbC addition, and the Fe2B secondary phase particles preferentially distribute along the grain boundaries in B-doped alloys. Precipitates could affect grain growth and improved the <100> orientation during directional solidification process. Small amount of precipitate element addition slightly increased the magnetostrictive strain, and a high value of 335 ppm under pre-stress of 15 MPa was achieved in the alloys with 0.1 at% NbC. Despite the fact that the effect on magnetic induction density of small amount of precipitates could be negligible, the coercivity markedly increased with addition of precipitate element for <TEX>$Fe_{83}Ga_{17}$</TEX> alloy due to the retarded domain motion resulted by precipitates.

A hybrid stochastic-weather-generation method for temporal disaggregation of precipitation with consideration of seasonality and within-month variations

Linking atmospheric and hydrological models is challenging because of a mismatch of spatial and temporal resolutions in which the models operate: dynamic hydrological models need input at relatively fine temporal (daily) scale, but the outputs from general circulation models are usually not realistic at the same scale, even though fine scale outputs are available. Temporal dimension downscaling methods called disaggregation are designed to produce finer temporal-scale data from reliable larger temporal-scale data. Here, we investigate a hybrid stochastic weather-generation method to simulate a high-frequency (daily) precipitation sequence based on lower frequency (monthly) amounts. To deal with many small precipitation amounts and capture large amounts, we divide the precipitation amounts on rainy days (with non-zero precipitation amounts) into two states (named moist and wet states, respectively) by a pre-defined threshold and propose a multi-state Markov chain model for the occurrences of different states (also including non-rain days called dry state). The truncated Gamma and censored extended Burr XII distributions are then employed to model the precipitation amounts in the moist and wet states, respectively. This approach avoids the need to deal with discontinuity in the distribution, and ensures that the states (dry, moist and wet) and corresponding amounts in rainy days are well matched. The method also considers seasonality by constructing individual models for different months, and monthly variation by incorporating the low-frequency amounts as a model predictor. The proposed method is compared with existing models using typical catchment data in Australia with different climate conditions (non-seasonal rainfall, summer rainfall and winter rainfall patterns) and demonstrates better performances under several evaluation criteria which are important in hydrological studies.