高大平房仓散装稻谷储粮害虫年消长动态研究

采用粮食多功能扦样器对重庆市铜梁国家粮食储备库高大平房仓储粮害虫的发生规律进行调查,结果表明高大平房仓内优势种群为玉米象和书虱,谷蠹和扁谷盗有少量发生,赤拟谷盗的发生很少;害虫发生绝大多数集中在表层和上层;粮仓中央多于四周;温度条件是影响害虫发生发展的主要因素.对储粮害虫种群数量进行相关性分析发现玉米象和书虱的种群数量与总虫数的相关性较高;从垂直分布规律看表层储粮害虫种群数量与总虫数的相关性最高;从水平分布规律看东南区域种群数量与总虫数的相关性最高,且绝大多数达到显著水平.     

纤维比强度气象生态模型的研究

在前人的研究基础上,利用多个试验的结果,论证了铃期日均温、日最高温度、相对湿度是影响纤维比强度的关键因子,明确了品种遗传因子在最终的纤维比强度形成中所起的决定作用。参考了前人的比强度是多个棉纤维品质指标中受环境影响变异性最大的指标的研究结论,提出了比强度多因素气象生态模型多个模型形式。利用试验结果进行模型的拟合并进行了模型检验,确定了最高温度和相对湿度交互作用的模型为最佳的比强度模型。模型的形式为： , 。模拟值与观测值1：1直方图符合度好,MRSE为1.0282 cN/tex,证明了模型具有较好的预测性和较高的精度。     

造纸法再造烟叶纤维形态与物理指标的相关性分析

为研究造纸法再造烟叶的纤维形态与其物理指标的相关性问题,以国内外造纸法再造烟叶企业的主流产品为试验材料,采用统计的方法对再造烟叶产品的纤维长度、长度分布范围、纤维宽度、宽度分布范围与产品的物理指标之间的相关性进行研究。结果表明：（1）造纸法再造烟叶的纤维长度、纤维宽度与抗张强度呈极显著负相关,纤维宽度与填充值达到显著负相关,纤维长度与定量、纤维宽度与定量均达显著正相关。（2）对于纤维长度：分布范围0.6~1.2 mm、1.8~2.4 mm与抗张强度、1.2~1.4 mm与定量极显著相关;0~0.8 mm、2.8~3.0 mm与抗强强度、1.2~1.6 mm与厚度,2.2~2.4 mm与平衡含水率均显著相关。（3）对于纤维宽度：分布范围为10~20 μm、30~55 μm与抗张强度、50~55 μm与定量极显著相关,10 μm 以下与密度、10~15 μm、35~40 μm、45~50 μm、55 μm以上与定量、25~30 μm与阴燃速率、25~30 μm及55 μm以上与抗强强度显著相关。     

Elastic-plastic Solution of Expansion of Spherical Cavities under 3D Loading

In elastic-plastic solution of expansion of spherical cavities, based on Mohr-Coulomb strength criterion, the effect of intermediate principal stress on yield and failure of soil is not analyzed. Therefore, there is disparity between results obtained by Mohr-Coulomb strength criterion and those obtained from experimental data. In this paper, the elastic-plastic solution of expansion of spherical cavities, based on unified strength theory is established and unified solutions are obtained. The corresponding solutions of different materials can be obtained. The unified solution cannot only be used to fit the properties of the materials with different tension-pressure strength, but also those with equal tension-pressure strength. The results show that by this solution, full use of the properties of the materials can be attained to reduce supports, which is of important significance for engineering     

高压正静电场对柠檬表面蜡质亲水性的影响

为探明在静电保鲜过程中不同电场参数对柠檬表皮蜡质亲水分子的影响,以柠檬角质层中成分含量最多的十六烷酸分子为研究对象,用分子模拟与理论分析和试验研究相结合的方法测定高压正静电场对柠檬表皮蜡质亲水性影响。结果表明,利用Materials Studio软件预测出正电场强度为180 kV/m时,十六烷基分子的MSD指数和偶极矩值均达到最小,亲水性最低。进一步用傅立叶红外光谱仪检测到,200 kV/m处理6天对十六烷酸羟基基团的抑制效果最好。最后采用Photoshop软件进行表面润湿性分析,验证在200 kV/m处理6天效果最佳。该试验初步筛选出了适宜柠檬贮藏的高压静电场电磁学的最佳参数,可为今后实际应用过程中选取合适的电场强度提供理论依据。     

A Study on Lightweight Aggregate Concrete with High Fluidity

In this paper, the influence of fly ash (FA), blast furnace slag (BS) and silica fume (SF) on the properties of lightweight aggregate concrete (LAC) with high fluidity were studied. Results show that in LAC the effects of composite additives are better than that of single additive. The slump of LAC with apparent density of 1 840 kg/m 3 could reach 267 mm and the spread 650 mm. The 28d strength is 28.8 MPa for LAC with 20% ground FA and 20% BS as additives and the shale ceramsite with bulk density of 503 kg/m 3 and crushing strength 3.1 MPa was used as aggregate. Physical properties of lightweight aggregate have significant effects on durability of the flowing LAC.     

大跨度PC连续刚构桥徐变预测模型

为了能准确预测混凝土收缩徐变,提出了一系列徐变预测模型,但传统的徐变理论研究主要是针对普通混凝土进行的,所提出的徐变模型并不能完全适用于高强混凝土。对各徐变预测模型进行分析比较,最终参考了日本混凝土示方书建议模型,并在高强混凝土徐变试验的基础上,提出了一个适用于高强混凝土的徐变预测模型。基于Abaqus平台,使用Python语言进行二次开发,定义了修正模型的徐变规律,并采用修正后的模型计算牛角坪大桥的徐变应变。结果表明,修正模型的精度,能很好的满足工程需求。     

宝天曼自然保护区主要树木种群竞争数量关系

应用53株对象木及其竞争木的调查数据,采用Hegyi单木竞争指数模型,对宝天曼地区锐齿栎和化香树木种群的种内和种间竞争数量关系进行了定量分析。结果表明,锐齿栎树木种群的种内竞争大于种间竞争,化香树木种群的种内竞争小于种间竞争。对距对象木2、4、6、8m范围内的竞争强度计算结果表明,锐齿栎和化香种群竞争强度最大值均出现在 0-2m的范围内。对象木竞争强度与胸径大小的关系服从幂函数曲线模型,且胸径达到20cm后竞争强度的明显减小。     

AN EXPERIMENTAL RESEARCH ON ENHANCEMENT OF HEAT TRANSFER OF FINNED TUBES IN REFRIGERANT HEAT EXCHANGER

In this paper,the comparative experimental research that air flows through theout-surface of a single row finned tubes is done in a drawing wind tunnel and the three differnetshapes of rectangluar finned tubes are compared with a plain finned tube that is usually used in therefrigerant heat exchanger, the useful results are obtained. The results show that,in the range ofwind velocity flowing through the marrowest area, W_(max)=2.5m/s to 8.5m/s,the average convec-tion heat transfer coefficient of the two-side V-groove finned tube is higher than that of rectangluarplain finned tube,It is a new type finned tube that has good heat transfer performance and it isworth poplarlzing.     

THE EFFECT OF THE BOND STRENGTH BETWEEN LAYERS ON COMPRESSIVE MECHANICAL PROPERTIES OF THE COMPOSITE ROCK

In this paper, on the basis of the compressive tests of composte rock, the different kinds of mechanical properties of composite rock under different bond states are discussed. Authers found that all mechanical properties of composite rock relate to the bond strength between layers and are dilferent when the layers'' bond strength is changed. With increasing the bond strength between layers of the composite rock, the limiting strength, elastic modulus, and breaking energy increase, and this phenomenon is to be stability gradually when they reach some volue, with increasing the layers'' bond strength, the poson ratio reduces.     

Study on the Terzaghi Ultimate Bearing Capacity of Foundation Based on the Unified Strength Theory

The ultimate bearing capacity of foundation based on Mohr-Coulomb strength criterion did not analyze effect of intermediate principal stress on yield and failure of soil so that the disparity between results obtained using Mohr-Coulomb strength criterion and those from experimental data are produced .In the paper , The ultimate bearing capacity of foundation based on unified strength theory is established and a unified solutions are obtained. The corresponding solutions of different materials can be got from it .The unified solution can not only be used to fit the properties of the materials with different tension-pressure strength but also those with equal tension-pressure strength, Results show that ones make full use of the properties of the materials so as to reduce supports,which is of important significance for engineering.     

Strength-permeability Model of Pervious Cement Concrete

High permeability is an important characteristic of pervious concrete. For the existing permeability testing devices of pervious concrete, the specimen sidewall leakage is serious due to the large numbers of open pores on the surface of specimens. To solve the problem, a new permeability testing method for pervious concrete was developed and a composite sidewall structure with waterproof daub, flexible rubber cushion and rigid sleeve sidewall was proposed. Meanwhile, the strength and permeability of pervious cement concrete are incompatible with a reciprocal relationship. However, limited research has been conducted on the relationship between them. Effects of water-cement ratio (W/C), aggregate-cement ratio and porosity on the properties of pervious concrete, including strength and permeability, were studied. Furthermore, strength-porosity model, permeability-porosity model and strength-permeability model were established. Tests reveal that: a) There is an optimum W/C of pervious concrete, at which strength reaches the maximum; b) The relationship between the strength and W/C shows a downward quadratic curve, and the permeability is proportional to porosity and aggregate-cement ratio; c) The relationship between strength and permeability of pervious cement concrete can be well fitted with the Lorentzian function, and the strength decreases when the permeability increases, but the rate of reduction decreases gradually. The optimum combination of strength and permeability should be determined based on the specific engineering requirements in design.     

丹参干燥工艺参数的研究

丹参是重要的中药材,为了保证丹参的加工质量,对丹参根采收后的干燥进行了试验研究。通过正交试验,研究了风温、风速和物料层厚度对丹参色泽、气味和干燥时间的影响。通过研究可知,当风温取70℃,风速取0.7m/s时,丹参色泽和气味较好;当风温取70℃,风速取1.0m/s时,丹参干燥最快,总干燥时间约210min。     

固沙植物沙米光合特性研究

采用Li—6200光合分析仪对沙地一年生植物种沙米的Pn进行了日变化和季节变化测试,结果表明：沙米光合速率日变化呈双峰曲线,其Pn第一峰值和第二峰值分别为13.38μmol/(m2·s)和9.428μmol/(m2·s)。沙米Pn在季节变化中平均高峰值在7月份为7.3428μmol/(m2·s)。沙米的光补偿点较低为127.3μmol/(m2·s)。在生长季节中沙米的水分利用效率（WUE）平均值为0.5707,最大平均值出现在6月份为0.7145。经对沙米Pn及其多项影响因子的相关分析,得出：沙米Pn与其因子QNTM、EAIR、TRAN呈极显著正相关关系相关;与CINT呈显著负相关关系。并得出沙米Pn及影响因子之间的回归方程。     

玉米茎秆弯曲性能与抗倒能力的研究

为探讨不同玉米品种茎秆抗倒伏相关的力学特点, 选用不同抗倒性品种登海3719、京科519和农大108, 设置3.00、5.25、7.50、9.25和12.00万 hm-2 5个密度, 分别于玉米抽雄前和蜡熟期取样, 用WDW3020型电子万能试验机对茎秆第3、5、7节间进行悬臂梁弯曲试验, 同时测定节间形态特征。结果表明, 随密度的增加, 茎秆基部节间直径变细、节间长度增长。品种间有一定的差异, 在3个品种中登海3719的平均直径和长度均低于其他2个品种; 品种间茎秆惯性矩也有较大差异。基部节间弹性模量、最大抗弯应力均随生育进程而增加, 但随群体密度的增加和节位的上升而逐渐降低, 登海3719在两个生育期均为最大, 且随密度增加的下降幅度较小。以京科519最低, 其对密度反应较敏感, 下降幅度大, 易发生倒伏。在玉米抽雄期, 基部节间平均弹性模量为40.0 MPa, 最大抗弯应力为2.8 MPa, 可能是茎秆抗折力学指标的下限。茎秆弹性模量与最大抗弯应力极显著相关, 茎秆直径与弹性模量和最大抗弯应力在抽雄前显著正相关, 而到蜡熟期相关不显著。它们与田间倒伏率呈极显著负相关。茎秆弯曲弹性模量反映茎秆的耐密能力, 茎秆最大抗弯应力反映品种茎秆的抗折能力, 而茎秆直径不能作为评价茎秆抗弯强弱的主要指标。玉米抽雄前期与蜡熟期茎秆抗弯性状的变化规律基本一致, 因此利用抽雄前茎秆基部弯曲力学性能鉴定与评价玉米茎秆抗倒、耐密性是可行的。     

华南8号木薯光响应参数日变化及其主要影响因子

摘要：采用Li-6400光合作用测定仪研究华南8号木薯的光合作用日进程,结果表明：华南8号的Pmax日变化呈单峰曲线,峰值出现在上午9:00左右,“午休现象”不明显。午间叶片光合能力的轻微减弱主要受到非气孔因素影响。最大净光合速率（Pmax）、表观量子效率（a）、光补偿点（LCP）、光饱和点（LSP）等光合参数在一天中是不断变化的。7:00～17:00,Pmax（CO2）变幅为：23.65～32.87μmol?m-2?s-1;a变幅为：0.0482～0.0683;LCP变幅为：30.60 ～50.78μmol?m-2 s-1;LSP变幅为：1845.64 ～2418.60μmol?m-2 s-1。多元逐步回归分析结果表明：各光合参数的主要影响因子分别是,a为RH,显著正效应;LCP为PAR,显著正效应;LSP为Cond和Vpdl,其中Cond为显著正效应,Vpdl为不显著负效应,效应大小依次为Cond＞-Vpdl;Pmax的主要影响因子是Cond、RH和Ci,其中Cond和RH为极显著正效应,Ci为不显著负效应,效应大小依次为Cond＞RH＞-Ci。     

巴基斯坦农业发展与中巴农业合作探析

为深入研究巴基斯坦农业发展基本情况,探索深化中巴农业合作的领域。结合国内外研究成果,在对文献资料进行梳理和综述的基础上,对巴农业资源、产业结构、管理机构设置进行了介绍。认为中巴农业合作存在规划性不强、深度不够、形式单一、地域重叠等问题,提出加强双边农业互访、合作制定中巴农业合作规划、拓宽合作领域等进一步加强中巴农业合作的建议。     

魔芋新品种——珠芽魔芋的初步应用研究

珠芽魔芋作为野生魔芋新品种,因具有繁殖系数大、抗性强、产量高等特点,而体现出明显的种植、栽培优势。对3个品种的珠芽魔芋进行黏度和凝胶强度方面应用性试验,并与普通的产品魔芋胶、魔芋精粉进行对比,以期客观深入地了解魔芋新品种在食品及添加剂中的性能,并初步分析其应用状况,以便珠芽魔芋这个新品种可以更好地得到应用和推广。     

氮制冷高温冷藏库气流流速的研究

对苍山冷链物流试验站高温冷藏库内气流分布情况进行了实地测定分析。结果表明,空库与满库货架和货架通道上半部分以及中央通道内气流流速有显著差异,货架与货架通道下半部分气流流速相同。高温库满库后其大部分区域空气流速远不能够达到正常气流流速的要求。建议在果蔬预冷期和正常贮藏期间货堆的空气流速分别控制在0．80～1．00m/s和0-30～0．50m／s之间。     

Experimental Analysis of Time-dependent Shear Behavior on Stud Connectors

With regard to the long span continuous composite beams, the early composite shear stud strength at the joint surface between the steel girder and concrete slab at different concrete ages should be considered while the concrete slabs are casted by phases in construction stage. In this study, the push-out test of stud shear connectors were conduced at different concrete ages. Meanwhile, the change law of the ultimate shear strength, ultimate slip deformation, design shear strength, and shear stiffness of the stud shear connectors with concrete ages were analyzed, and the corresponding time-dependent calculation equations were presented. The results include that the main failure modes of stud shear connectors are the concrete slab splitting failure before 3-days concrete age. The load-slip laws of stud shear connectors at different concrete ages are basically the same, however, the shear strength and stiffness all increase with the concrete ages prolonging, and the increase degree is faster at early ages, but slower at later ages, which indicates that the early composite shear stud strength at the joint surface of composite beams should not be neglected.