Numerical simulation and optimization of flow and temperature fields for wide slab cast mold

Fluid flow and temperature distribution in a wide slab continuous caster mold are simulated using the commercial software FLUENT. The research results show that the longitudinal cracks in the wide slab surface with an original submerged entry nozzle (SEN) mainly are caused by weak upper flow circulation in the mold, slow heat exchange near the meniscus, and non uniform melting of the mold powder. Therefore, a modified SEN with smaller outlet thickness, a 15° downward port angle, and convex bottom is designed to overcome the disadvantages of the original nozzle. The characteristics of the molten steel flow are analyzed by numerical simulation. The results indicate that the parameters of the optimum SEN are more highly optimized than the original SEN. The trial results also show that the optimum SEN possesses a better application effect.     

Water model study on flow optimization of five streams L-type tundish

In this paper, the water model method is used to optimize the flow behavior of asymmetrical five streams L-type tundish in a steelmaking plant. The results show that the optimization plan is set up with turbulence suppressor T+ vice guide wall D2+ main guide wall with three holes (D1a) which consists of top two holes with 25° inclination and one hole with 30° inclination below. With this plan, the time which the colorants reach to the outlets increases, the difference of response time in all outlets decreases, the peak concentration of the RTD reduces, the existence time of high concentration liquid steel extends, and the ratio of dead zone in each streams reduces.     

Effects of weather variables on sugar beet yield development (Beta vulgaris L.)

There is much data on the impact of weather variables on the growth of sugar beet from studies conducted under controlled conditions or single field experiments, but these data are of only limited validity for other sites or larger areas. The aim of the present study was to quantify the influence of weather conditions on the growth of sugar beet for the further development of simulation models, based on data representative of sugar beet cultivation in Germany. For this purpose, 27 field trials were conducted in 2000–2001 in commercial fields with variable climatic and soil conditions. From the end of May until the end of the season, beets were harvested manually every 4 weeks, the dry matter yield of leaves and taproot was determined and their growth rates were calculated. Temperature, solar radiation, rainfall and humidity were recorded daily for each site and the potential evapotranspiration and climatic water balance were estimated. The soil water content to a depth of 0.9 m was determined at every harvest date.Several functions were developed to describe the growth of sugar beet as affected by the given meteorological variables. From sowing to the end of June, the dry matter accumulation of both leaves and taproot was strongly enhanced by increasing temperature and during this period leaf dry matter increased linearly with thermal time. After reaching 700 °C d, the taproot dry matter accumulated exponentially with thermal time. The optimum mean daily air temperature for taproot growth was approximately 18 °C. Higher temperature occurring in July and August decreased final taproot yield, but by the end of the season, growth was independent of temperature. High solar radiation advanced growth during the first 65 days after sowing and again in October.Neither the water input by rainfall and irrigation nor the climatic water balance adequately described the growth of the leaves or taproot, but it was shown that the increase in taproot dry matter during July and August depended on the amount of available water in the soil. The maximum sugar yield that can theoretically be achieved in Germany and comparable agroclimatic regions was calculated as 24 t ha⁻¹. The present data reliable for a large agroclimatic region in Europe are of significant value as input for simulation models.     

太阳能制冷机组通风系统中粮库温度的系统分析

针对不同的粮库内部太阳能制冷机组空调分布形式,利用CFD计算软件,采用标准k-e模型对粮库内部的大空间气流组织的非稳定特性进行三维数值模拟,分别比较了集中辐射式分布和沿四壁周向式分布两种形式的粮食表面附近的截平面的速度和温度分布,模拟结果显示:采用集中辐射式分布的模型流场扰动范围大,换热效果好,温度场分布均匀,整体降温效果好.由此可以看出流体计算技术在研究空调换热空间速度场和温度场分布的巨大作用,为空调的设计运行参数提供了重要依据,从而可以选用换热效果更好的空调分布形式.     

基于多视角反射光谱的冬小麦冠层叶片氮素营养监测研究

通过2个蛋白质含量不同的冬小麦品种和4个氮素水平的试验,研究传感器在垂直冬小麦垄平面上,冠层不同观测角度的反射光谱与叶片氮素营养的关系,改进小麦冠层氮素光谱诊断的理论与方法。结果表明,在本试验选择的7种植被指数光谱特征参量中,2个小麦品种均表现为比值植被指数（RVI[670,890]）与冠层叶片氮素含量（CLNC）相关性最高;不同视角的RVI与冠层叶片氮素含量关系中,0°、30°和90°的相关性最高;利用0°、30°和90°的RVI与CLNC进行模型拟合,其模型的决定系数是0°﹥30°﹥90°;在建立的0°模型中,京411小麦模型RMSE为0.2915,预测准确率为90.2%,中优9507模型RMSE为0.3827,预测准确率为87.2%。本研究证明改变反射光谱观测角度,能够提高冠层叶片氮素含量的光谱预测精度,不同小麦品种其光谱特征与冠层叶片氮素含量关系不同,在应用中要根据不同的小麦品种建立相应的模型。     

Numerical simulation of gas solid characteristics in double inlet square cyclone separator

This paper uses RSM turbulence model to conduct the numerical simulation on the gas flow field in double inlet square separator and calculate the velocity field and pressure distribution in the seperator. At the same time, it simulates the solid particle trajectories in the separators using Lagrangian model. The results show that the velocity field and pressure distribution in double inlet square separator have good symmetry, but the flow swirl intensity is insufficient and easy to decay; different sizes and different injection locations bring significant differences for the particle trajectories; injecting small particles can be easy to form flow short-circuit phenomenon inside the separator, injecting particles near the top of separator can be easy to form top ash ring phenomenon inside the separator; these phenomena have adverse factors to the separation efficiency. When the separation cylinder corners of square separator are changed into cutting-shaped chamfers, the flow field in the separator can be improved, and the separation efficiency of separator can be effectively improved.     

小型水稻收割机纵轴流脱粒分离装置结构设计与试验

为解决中国南方丘陵山区大型收割机具通过性差,横轴流式收割机脱粒损失率大的难题,设计一种小型轴流式水稻联合收割机脱粒装置,将其装配在收割机整机上进行了田间脱粒损失率试验。结果表明：弹性脱粒杆齿齿距、导条螺旋升角、凹板筛直条倾角3 个影响因素对水稻脱粒损失率影响显著;对各因素最优组合的取值为弹性脱粒杆齿齿距a=90 mm,导条螺旋升角α =23°,凹板筛直条倾角θ =14°,此时的水稻脱粒损失率为1.51%,达到国家标准小于3%的要求,试验数据为小型轴流式水稻联合收割机的产业化提供了技术保障。     

Impact of high temperatures on the marketable tuber yield and related traits of potato

A rapid warming of 2.8–5.3 °C by the end of this century is expected in South Korea. Considering the current temperature during the spring potato growing season (emergence to harvest; ca. 18 °C), which is near the upper limit of the optimum temperature for potato yield, the anticipated warming will adversely affect potato production in South Korea. The present study assessed the impact of high temperature on the marketable tuber yield and related traits of cv. Superior (which makes up 71% of the annual potato production in South Korea) in four temperature-controlled plastic houses and an outdoor field (37.27°N, 126.99°E) during 2015–2016. The target temperatures of the four plastic houses were set to ambient (AT), AT+1.5 °C, AT+3.0 °C, and AT+5.0 °C. The marketable tuber yield was significantly reduced by 11% per 1 °C increase over a temperature range of 19.1–27.7 °C. The negative impact of high temperature was associated not only with the yield loss of total tubers, which was mostly explained by the slower tuber bulking rate, but also the reduced marketable tuber ratio under temperatures above 23 °C, which was mainly attributed to the reduced number of marketable tubers (r = 0.79***). Under moderate temperatures below 23 °C, the source limited the number of marketable tubers without reducing the marketable tuber ratio. In contrast, the number of marketable tubers was limited by the marketable tuber set at the early growth stage rather than the source under the higher temperatures, which resulted in the reduction in the marketable tuber ratio below 56%. These results suggest that the objectives of breeding and agronomic management for adapting to the rapid warming in South Korea should include maintaining the ability to form tubers at the early growth stage under high temperatures, as well as the photosynthetic capacity and sink strength of the tubers.     

Maize ear temperature

An experimental study of ear temperature was made in Morocco (June, 1997) and in Belgium (September, 1998). Measurements were made at mid-length of ear in the centre of cob and at different points in the middle of grains. The results showed that temperature in the middle of the grains depends significantly on the position of grain around the ear axis, especially in Morocco, between 13 and 16 h (UT). The result obtained shoed that, because of the considerable ear thermal inertia and non-isotropic direction of the direct solar radiation, the average temperatures in the middle of the grain and in the centre of the cob were similar. The difference between grain and air temperature was shown to be clearly more affected by solar radiation than by wind speed. The protection of ear against direct solar radiation led to an average temperature reduction of about 2.1°C in ear protected compared with normal ears. Also, the important role played by the canopy on ear temperature was underlined. A temperature difference of up to 8.5°C was observed between the temperature of ears exposed to direct radiation and other (normal) ears. The effects of the differences observed between grain temperatures on both final weight grain and kernel growth rate were calculated using CERES-Maize functions. These effects were shown unlikely to affect drastically grain yield.     

T型斜叶桨作用下油辣椒多相流数值分析

利用Fluent仿真软件，以辣椒颗粒、肉丁和豆油构成的多相混合流体为研究对象，结合Eulerian多相流模型，研究了T型斜叶桨和开启式斜叶桨作用下的速度场、密度场、各相体积分数分布及功率消耗状况。结果表明：当转速为6 rad/s时，在T型斜叶桨作用下，虽然功耗有所增加，但混合物的整体流动速度提高，絮流强度增加，料槽底部高密度区域得到改善；各单相体积分数分布与初始设定值较为接近，可实现油辣椒的均匀化混合。计算结果为油辣椒搅拌机理研究提供一定理论参考。     

Hydrogen peroxide reduces heat‐induced yield losses in cotton (Gossypium hirsutum L.) by protecting cellular membrane damage

We investigated the effect of various growth substances such as hydrogen peroxide, salicylic acid (SA), moringa leaf‐extract (MLE) and ascorbic acid (ASA) on leaf physiology and seed cotton yield (SCY) of heat‐stressed cotton. Cotton plants were exposed to elevated temperatures at three reproductive stages, either by staggering planting time in the field or by increasing growth cabinet temperatures (38/24°C and 45/30°C) in glasshouse. Elevated temperature at any reproductive phase significantly damaged cellular membrane and reduced SCY. Plants exposed to 38/24°C and 45/30°C in glasshouse produced 63% and 22% lower SCY, respectively, compared with plants under optimal temperature ((32/20°C). In response to high temperature, cotton plants up‐regulated activities of anti‐oxidative enzymes e.g. peroxidase and ascorbic acid. However, this defensive system could not protect cellular membrane of stressed plants from extreme temperature (38 and 45°C). In contrast, growth substances such as H2O2, ASA and MLE significantly increased anti‐oxidative enzymes activity to an extent, which reduced heat‐induced damage to cellular membrane. No significant effect of any regulator was observed on SCY under optimum temperatures; although H2O2, MLE and ASA significantly increased SCY of heat‐stressed cotton. Hydrogen peroxide increased SCY of April and May thermal regimes crops by 16% (averaged across both sowing dates) under field, while it caused 14% and 20% increase in SCY of plants exposed to sub (38/24°C) and supra optimal (45/30°C) thermal regimes under glasshouse. We concluded that growth regulators, specifically, H2O2 can protect cotton crops from heat‐induced cellular membrane damage by up‐regulating antioxidant defense system.     

三连栋日光温室温度场分布及应用

针对冀中南地区冬季雾霾天气严重,日光温室不能充分发挥其应有的保温功能,设计建造了三连栋日光温室,为进一步验证其性能,应用MATLAB软件对三连栋日光温室进行二维温度场的拟合和图像绘制。结果表明：00:23三连栋日光温室的温度为8日>9日>10日;06:23为温室一天的最低温度,10日的06:23为3天最低温度;12:23为多云~阴的8日温室的最高温度,14:23为阴~晴的9日温室的最高温度,12:23—14:23为晴天的10日温室的最高温度,3天温室最高温均能达到30℃,16:23温度下降较快。多云~阴的8日、阴~晴的9日09:23—10:23依次从温室的北、中、南栋的上中部开始升温,16:23先从温室下部开始降温;晴天的10日09:23—10:23依次从温室的南、中、北栋开始升温,16:23依次从温室的北、中、南栋开始降温。在温室温度最低时或最高时,北栋北后侧中下部区域为温度的最高点或最低点。8—10日09:23与18:23(15~20℃)、08:23与20:23(10~15℃)温室温度各栋之间及各区域基本相同。同一天内温室地温中栋最高,地温白天北栋最低、夜间南栋最低;10日夜间南栋地温最低,最低地温13℃,白天中栋地温最高,最高地温22℃。光照强度9日<8日<10日。三连栋日光温室在2月中旬喜温果菜类即可定植,较单膜塑料大棚提早定植25~30天,同时又规避了冬季低温阴雪雾霾天气出现频次高的时段,三连栋日光温室优势明显。     

Temperature effects on seed germination and expression of seed dormancy in wheat

Because preharvest sprouting decreases quantity and quality of wheat grain, researchers need effective protocols to assess response to preharvest sprouting conditions. The aim of this study was to determine which temperature gives the greatest difference in seed germination and expression of seed dormancy in 10 spring wheat genotypes. The genotypes were grown in the field near Swift Current, Saskatchewan in 2000 in a randomized complete block with four replicates. Seed samples were harvested at approximately 25% moisture content (wet weight basis) and dried to 12% moisture content with minimal after-ripening. Germination was under controlled environment at temperatures of 10, 15, 20 and 30 °C in darkness. A weighted germination index (WGI) was calculated. The analysis of WGI, for each temperature, showed highly significant (p ≤ 0.01) genotype effects on germination. Most genotypes decreased in WGI (increased dormancy) as temperature was increased from 10 to 30 °C. The greatest differences in seed germination tended to be at 15 °C and 20 °C. The level of seed dormancy depended on the genotype and germination temperature. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of 1-methylcyclopropene on ripening of greenhouse tomatoes at three storage temperatures

Tomatoes (Lycopersicon esculentum Mill., cv. Rapsodie) were harvested at the mature green stage and treated with 250 nl l⁻¹ 1-methylcyclopropene (1-MCP) for 24 h at 20 °C. The fruit were then stored for 24 days at 15, 20 or 25 °C at 90–95% relative humidity. Sampling was carried out at 0, 6, 12, 18 and 24 days after treatment. Treatment with 1-MCP delayed ripening as measured by changes in lycopene, chlorophyll, hue angle, polygalacturonase (PG) activity and tissue firmness. Ripening was delayed by 6 days at 25 °C, by 12 days at 20 °C, and by 18 days at 15 °C in 1-MCP-treated fruit. In general, 1-MCP only delayed the onset of ripening-related changes and did not significantly alter final values for measures of firmness, color (hue angle), PG activity, and lycopene and chlorophyll contents at a particular storage temperature. The results suggest that 1-MCP is most effective at delaying ripening of mature-green tomatoes when they are stored near the currently recommended temperature range of 12.5–15 °C.     

contact stress and steady thermal analysis of herringbone gears in a gas turbine

To obtain the distribution characteristic of contact stress and the bulk temperature on the surface of herringbone gears, parameter modeling of gears was carried out by parametric design language. A numerical simulation was given to calculate the contact stress field and the steady thermal field by combining heat transfer theory, tribology theory, and mesh theory. The distribution of contact stress, the bulk temperature and heat flux also were analyzed. The analysis results show that the distribution of the load along the contact line possesses regularity. The heat flux along the tooth depth direction decreases first and then increases. The effect of thermal conduction of the tooth is stronger than that of convective heat transfer. The conclusion indicates that the finite element emulation method can be used to estimate the transmission performance of herringbone gears.     

A Simplified Method to Calculate the Wet Bulb Globe Temperature

The wet bulb globe temperature (WBGT) is difficult to measure and calculate in field observation and numerical simulation. To solve this problem, the air dry bulb temperature, wet bulb temperature, globe temperature, relative humidity, mean air velocity, solar radiation and wet bulb globe temperature in Guangzhou, P. R. China, first were collected during the summer (July). Next, correlation and regression analyses were used to derive a simplified model for calculating WBGT. The results show that dry bulb temperature, relative humidity, solar radiation, mean air velocity and WBGT were interrelated to some extent. These four parameters with high linear correlation can be used to predict WBGT in a simplified model with high precision. The simplified WBGT model can be used in field observation and simulation research regarding urban thermal environments.     

Measurement methodology of color reflectionperformance of building facing materials

With the measurement of reflection spectrum and the experimental measurement of illumination observing angle, color temperature of light source, effects of field viewing angles, it is found that the color of facing materials have relation to light incidence and observing angle. The chroma number varies with the changing of light incidence and observing angle based on the features of facing materials. The chroma number has more fluctuation with the angle close to mirror reflection direction while it is more steady with other angles. Besides, the mirror reflection phenomenon is not obvious for sub brightness facing tile. The color temperature of light source affects material color and the chroma number varies with the incidence changing, etc. All of these have provided fundamental for quantitative study of architecture color design.     

不同生长型桃的叶脉结构与树体结构的差异与关系

为探讨开张型、直立型、垂枝型、帚形、矮化型和紧凑型不同生长型桃树叶脉结构与树体结构的关系,为桃矮化密植栽培、早期选择提供理论依据。以6种不同生长型桃为试材,对其树体结构特征和叶片形态、叶脉结构进行研究,并对树体结构与叶脉结构的关系进行分析。结果表明:6种生长型桃的叶片角度大小为62.76°~73.50°,没有显著差异,而分枝角度存在显著差异。其中对一级枝基角而言,垂枝型93.92°最大,矮化型36.75°最小,其他4种生长型居中;而一级枝腰角和梢角的变化规律在6种生长型中表现出相似规律,即垂枝型最大,开张型居中,其他4种次之且相互之间差异不显著。在叶片结构特征方面,直立型的叶片长度11.01 cm为最小,但叶柄长2.41 cm最大,紧凑型叶片长度16.20 cm、叶宽4.57 cm、叶面积47.28 cm2均最大,6种生长型的叶脉均为真曲行羽状脉;直立型二级脉数量最多,垂枝型二级脉数量最少;开张型二级脉角度最大,矮化型二级脉角度最小。6种生长型桃叶脉结构和树体结构相关性分析结果表明:开张型、矮化型、紧凑型中,二级脉数量与一级枝梢角之间存在负相关关系,且仅在开张型中两者相关性达到显著水平,相关系数为-0.970,而在直立型、垂枝型和帚型中,二级脉数量与一级枝梢角之间有正相关关系;在开张型、矮化型、紧凑型中二级脉角度与一级枝梢角呈正相关,且紧凑型中两者相关性达到显著水平,相关系数为0.953,其余生长型中两者之间有负相关关系。桃叶脉的二级脉角度和二级脉数量的差异在一定程度上可以反映不同生长型桃树体结构的变化,可作为早期选择桃不同生长型的一项直观形态标记。     

卫星资料在山西暴雨数值预报中的初步应用

旨在应用卫星云顶数据改进数值模式的水汽初始场,探讨利用卫星资料改进定量降水预报的可能性。利用ADAS(ARPSDataAnalysisSystem)综合云分析系统,将静止卫星云顶亮温数据加入到WRF中尺度模式中,对2013年7月9日夜间山西南部一次暴雨过程进行数值模拟和对比试验。结果表明：此次强降水过程发生在高空槽引导西北涡东移的环流背景下,低涡切变线附近生成的中-β尺度强对流云团是造成此次强降水的直接影响系统。融合卫星云顶数据改善了模式24h降水预报效果,有效减少强降水的空报,显著提高暴雨以上强降水的预报效果。进一步分析表明：融合卫星云顶数据后,模式可以获取中尺度系统信息,可以捕捉中-β尺度强对流云团;模式有效加强了对降水有重要影响的高湿区的分析,动力场能够快速协调适应;模式更加有效地预报出未来3h内降水模态的变化和移动,显著改善了强降水的临近预报效果。     

Effects of Mild Temperature Stress on Grain Quality and Root and Straw Nitrogen Concentration in Malting Barley Cultivars

Abstract It is a challenge to obtain the appropriate protein concentration in cereals for the intended end‐use. This study examined ambient temperature effects on two spring malting barley cultivars (Henley and Tipple) grown in soil or in solution culture with controlled nitrogen supply in daylight chambers with low temperature (day 18 °C, night 12 °C), and high temperature (23 °C/17 °C) to/after anthesis. In soil‐grown plants, high temperature to anthesis resulted in higher grain nitrogen amount (GNA), grain nitrogen concentration (GNC) and straw nitrogen concentration (SNC). In plants grown in solution, high temperature to anthesis resulted in lower GNA and higher GNC. A temperature rise of 1 °C during the growing period in solution cultivation increased GNC, root nitrogen concentration (RNC) and SNC, by 1.20, 1.35 and 0.33 mg g^?1, respectively. In solution culture, GNC was positively correlated with RNC and SNC (P < 0.01). Cv. Henley had higher GNC but lower SNC than cv. Tipple. Cv. Henley was more stable in grain size and cv. Tipple in GNC. The results showed that temperature has a direct effect on GNC. Accounting for temperature fluctuations up to the latest possible nitrogen fertilisation occasion can therefore help when deciding appropriate nitrogen supply for intended end‐use.