预测平房仓中小麦密度分布与储藏质量的模型

采用LHT-1粮食回弹模量仪测定小麦堆在不同压应力下的压缩密度,结果表明:当小麦[众麦1号,含水率为11.70%~18.18%(w.b.)]的竖直压应力增大(0.631~221.060 k Pa)压缩密度增大(740.50~853.85 kg/m~3),两者可拟合出关系方程。建立平房仓中小麦的密度、应力与粮层深度关系的微分方程组,用数值方法计算平房仓中小麦密度与粮层深度关系,由积分法计算出平房仓中小麦的储藏质量。模型计算结果表明:平房仓中小麦密度随着粮层深度的增加而增大,随着深度增加,密度增加率减小;在一个宽20 m,长40 m的平房仓中,小麦密度从表层的800 kg/m~3增加到10 m深处的833.5 kg/m~3,密度增加了4.1%。在同一深处,密度随平房仓长、宽的尺寸增大而增大,增大值很小。在平房仓中同一深处,密度随含水率的增大而增大,增大值很小。小麦的摩擦角、小麦与仓壁摩擦系数几乎不影响平房仓中的密度。本模型计算了5个实仓中的小麦储藏质量,计算值与粮重实际账面数几乎一致,最大误差为2.63%。     

基于有限元方法的平房仓中小麦堆的密度分布研究

选定剑桥修正模型作为小麦堆的应力与应变关系本构方程,使用有限元方法计算平房仓中小麦堆的应变分布值,由应变值计算出平房仓中小麦堆的密度分布值。结果表明：小麦储藏在平房仓中,其堆密度分布是不均匀的。在同一含水率下,小麦平均层密度随着粮层深度的增加而增加,增加率随粮层深度的增加而减小;在同一粮层下,小麦的堆密度随距仓壁的距离减小而减小,在粮仓的拐角处小麦堆密度达到该层的最小值,当粮层深度越深,小麦堆层密度分布越不均匀;平房仓内小麦的平均堆密度随着含水率的增加而减小,平均堆密度相对于无压缩密度的增加率随含水率增加而增大;由剑桥修正模型计算出的数据拟合了平房仓中小麦平均层密度与粮层深度、含水率之间的关系方程。实仓验证得到：该模型计算的平房仓中小麦的重量与实仓内账面小麦重量的误差小于1.64%。     

平房仓中稻谷密度的时空分布值及堆高沉降特性研究

使用粮食回弹模量仪测定出稻谷堆的压缩密度与最大主应力（竖直压应力）及储藏时间的关系模型。选定修正剑桥模型作为稻谷堆的应力与应变关系本构方程,使用有限元方法计算出装粮后瞬时平房仓中稻谷层的竖直压应力分布值。由平房仓中稻谷堆各层的竖直压应力和稻谷堆的压缩密度与最大主应力（竖直压应力）及储藏时间的关系模型计算出平房仓中稻谷层的密度与粮层深度及储藏时间的关系模型。结果表明：稻谷堆压缩密度随最大主应力的增加而增大,随储藏时间的增加而增大,稻谷堆压缩密度关于储藏时间和最大主应力的关系模型是 ;平房仓中稻谷层密度随粮层深度的增加而增大,随储藏时间的增加而增大,平房仓中稻谷堆密度关于储藏时间和粮层深度的关系模型是 ;平房仓中稻谷堆高随储藏时间的增加而降低,且堆高降低幅度越来越小,最后稻谷堆高趋于稳定值。     

带锥斗筒仓中稻谷的密度与应力分布模型

采用LHT-1粮食回弹模量仪测定稻谷堆的压缩密度,建立带锥斗筒仓中稻谷堆的密度、应力与粮层深度关系的微分方程组,用数值方法计算带锥斗筒仓中稻谷密度、应力与粮层深度关系,由积分法计算出筒仓中稻谷的储藏总质量。试验结果表明,淮稻5号(含水率为10.38%~18.30%w.b.)的密度随竖直应力(0.495~245.892 kPa)增大而增大(582.772~696.593 kg/m~3)。模型计算结果表明,在带锥斗筒仓的筒体部分,稻谷堆密度随着粮层深度的增加而增大;到锥斗部分,稻谷堆密度随着粮层深度的增加而逐渐减小。在带锥斗筒仓的筒体部分,稻谷堆的竖直应力随着粮层深度的增加而增大;在锥斗部分,稻谷堆的竖直应力则随着粮层深度的增加而减小。在带锥斗筒仓中的筒体部分,稻谷堆的侧向应力随着粮层深度的增大而增大;在筒体与锥斗结合处,稻谷堆的侧向应力突然增加;到了锥斗部分,稻谷堆的侧向应力随着粮层深度的增大先稍增大再逐渐减小。     

筒仓中稻谷的空隙率分布研究

采用LHT-1粮食回弹模量仪测定稻谷(南粳5055)堆的表层密度及压缩密度,建立筒仓中稻谷堆的密度、应力与粮层深度关系的微分方程组,用数值方法计算筒仓中稻谷密度与粮层深度关系。采用粮食孔隙率测量仪测定表层稻谷(无压缩)孔隙率,由表层孔隙率,表层密度及筒仓深处的密度计算出筒仓中稻谷孔隙率与粮层深度关系。计算结果表明:在直径20米的筒仓中,在30米的筒体部分,南粳5055空隙率变化范围为61.00%~56.32%,在10 m的锥斗中,空隙率变化范围为56.32%~59.77%;在带锥斗筒仓的筒体部分,稻谷堆孔隙率随着粮层深度的增加而减小;到锥斗部分,稻谷堆孔隙率随着粮层深度的增加而逐渐增大。在不同直径的筒仓的筒体部分,在同一深度,稻谷堆孔隙率随着筒仓直径的增大而减小。     

筒仓中小麦密度分布值的有限元分析

筒仓中粮堆密度分布值是预测筒仓中粮食对仓壁的压力、确定粮食通风阻力、计算筒仓中粮食质量的关键参数.使用有限元方法求解小麦堆的修正剑桥模型计算出筒仓中小麦堆的密度分布值.结果 表明,筒仓中小麦堆的密度随着粮层深度的增加而逐渐增大,但在筒仓拐角处密度随着粮层深度的增加而逐渐减小.在上部粮层,粮块密度随着粮块与筒仓中心轴距离...     

横向通风技术在高大平房仓小麦储藏上的应用

探讨了横向通风技术在60 m×21 m高大平房仓小麦储藏上的应用,设计了横向通风系统方案。对实仓横向通风管网风速、风量、压力和粮堆内部静压等参数的研究测试结果表明,21 m跨度小麦高大平房仓横向通风系统中系统总阻力和单位粮层阻力随着单位通风量增大而增加,在实际降温通风作业过程中,单位通风量选取不应大于7 m3/h·t;横向通风系统中,通风途径比小,通风过程中粮堆内静压分布均匀,粮堆内气流分布比较均匀。     

柴油植物毛榛种仁油性质分析

本文参照我国国标规定的油脂性质的测定方法,测定了非粮柴油植物毛榛种仁的含油量、酸值、碘值、皂化值、水分及挥发物含量、折光指数、脂肪酸组成,结果表明毛榛种仁含油50.61%、密度917.0kg.m_-3、酸值0.9183mg.g_-1、碘值100.8g.(100g)_-1、皂化值179.0mg.g_-1,碳链长度主要集中在C14-C20之间,不饱和脂肪酸占90%以上,以油酸(C₁₈H₃₄O₂)和亚油酸(C₁₈H₃₂O₂)为主,分别为60.49%和28.72%。多元不饱和脂肪酸中三烯脂肪酸(亚麻酸)含量为0.56%,不含四烯及四烯以上脂肪酸。结果表明：毛榛种仁油性质优良,可作为北方地区重点开发的生物柴油原料植物。     

横向谷冷通风技术在平房仓小麦储藏中的应用

研究横向谷冷通风技术在平房仓小麦储藏中的应用。实验结果表明:平房仓采用横向谷冷通风技术后,通风路径较传统通风系统增加3倍以上,热交换效率明显提高,冷风量基本不浪费,且谷冷通风降温耗能低,降温后粮堆温度均匀性好。粮堆高度方向粮温基本一致,沿谷冷通风的气流前进方向温度梯度差平均不大于0.5℃/m。在平房仓小麦储藏中应用横向谷冷通风技术可实现与传统竖向谷冷通风相同的降温效果,而且其冷却效率和降温均匀性更好。     

空调控温储粮对稻谷储藏品质的影响研究

通过开展空调控温储粮试验,分析探讨不同粮层深度下的稻谷储藏品质变化情况,结果表明:储藏期内,试验仓和对照仓各层稻谷品质指标的变化趋势基本相同,均随着储藏时间的延长,水分、发芽率、品尝评分值呈下降趋势,脂肪酸值呈上升趋势;同时,通过比较不同粮层深度的稻谷品质变化情况,发现第1层(粮面)稻谷的各项品质指标变化幅度最大,而在相同粮层深度下,对照仓各层稻谷品质指标均比试验仓变化幅度大;试验证明,采用空调控温储粮,能有效延缓粮食品质劣变速度,是一种行之有效的稻谷安全储藏方法。     

PHYSICAL PROPERTIES OF GRAM AS A FUNCTION OF MOISTURE CONTENT

This study was carried out to determine the effect of moisture content on some physical properties of gram. Six levels of moisture content ranging from 10.83 to 31.20 percent (dry basis) were considered for this study. Length, width, thickness, diameter of equivalent sphere, mass of 1000 grains and porosity increased linearly from 7.968 to 8.758 mm, 5.864 to 6.554 mm, 5.713 to 6.359 mm, 6.770 to 8.795 mm, 137.97 to 172.73 g, and 33.17 to 35.85% respectively with the increase of moisture content from 10.83 to 31.20%. The angle of repose increased from 27.03 to 33.27° with the increase of moisture content. Bulk density and true density decreased linearly from 787.31 kg/m³ to 712.61 kg/m³ and 1398 kg/m³ to 1250 kg/m³, respectively. Static coefficient of friction was determined over plywood, galvanized steel, celluloid sheet, and glass sheet. Static coefficient of friction varied from material to material and depended on the roughness and wetness of the true. The highest coefficient of static friction was found over plywood and lowest for glass sheet among the materials tested.     

Peripheral milling properties of compressed wood manufactured from planted China-fir

Softwood exhibits different physical and mechanical properties in early wood and late wood, which often becomes the cause of some cutting defects during processing. These problems, however, can be partially solved by conversion into compressed wood. It can be expected that density and strength of the compressed wood increase with the increase in compression, thus affecting cutting resistance. The study on the machinability of compressed wood in order to justify its application is needed. In the test, green China-fir wood (Cunninghamia lanceolata) grown in plantations was compressed in radial direction using various compression sets, followed by peripheral milling parallel to the grain. The results showed that the horizontal cutting force increased with an increase in compression and depth of cut, but decreased with rake angle increase. The vertical cutting forces increased with an increase in cutting depth. No apparent relationship between vertical cutting force and compression was found. No significant difference existed in horizontal cutting forces beween up cutting and down cutting.     

小麦摩擦特性的试验研究

主要利用直剪仪对小麦(湿基含水量为13.55%、15.28%、16.60%、17.90%)的内摩擦角、小麦与不锈钢板的摩擦系数、小麦与混凝土板的摩擦系数进行了试验测定与比较。结果表明:小麦的内摩擦角变化范围是21.21～37.94°,小麦与不锈钢板的摩擦系数变化范围是0.25～0.63,小麦与混凝土板的摩擦系数变化范围是0.46～0.95,且均随法向压应力的增加而减小,随含水量的增加而增加。根据试验结果,分别拟合出内摩擦角、摩擦系数与法向压应力、含水量的关系方程。     

Investigation of sorption isotherms of wheat germ for its effect on lipid oxidation

This research aimed to investigate the oxidation and sorption isotherm properties of wheat germ and to determine monolayer moisture content (m₀) in particular, because it has a limiting effect on lipid oxidation. This research comprised two stages. The first stage was the determination of sorption properties and m₀ at three temperatures (15, 25, and 35°C). The second stage of the research was to investigate lipid oxidation properties of stored wheat germ at two different temperatures (4 and 25°C) and m₀ for 28 days. As a result, it was determined that wheat germ has a Type II sorption isotherm, Halsey is the best fitting sorption equation, and the average m₀ is 4.25 g moisture per 100 g dry matter. Furthermore, the free fatty acid and peroxide value of wheat germ oil increased with increasing storage moisture content and temperature, determined as 12.63% and 5.01 mEqO₂/kg on average, respectively. In conclusion, storage of impermeably packaged wheat germ at low temperature and m₀ content is an applicable method for decreasing rancidity and prolonging shelf-life.     

The influence of nitrogen fertilizer on grain quality in winter wheat

Between 1966 and 1969, 44 experiments on winter wheat tested 5 rates of N applied as spring top dressings of NH₄NO₃. At almost every site increasing the rate of N applied, decreased grain size and increased the N content of the grain. There was a marked effect of season: the sunniest season, 1969, produced the largest grain and the lowest mean N content; the season with the least soil moisture deficit, 1968, produced the highest mean N content. There was no relationship between N content and the variety of wheat or soil type. The N content of grain grown without N fertiliser was highly significantly related to reserves of available N in the soil. i.e. to the rate of fertilizer N required for maximum grain yield, determined by experiment. By using this relationship, the fertilizer N requirement at 20 sites with nil N plots was calculated and was found to compare favourably with the ADAS N Index prediction method based largely on previous cropping. Grain density was determined on three sites in 1967; with increasing rates of N, grain density increased slightly.