Analysis Theory of Unbonded Prestressed Concrete Continuous Beams

In this paper, the energy method has been used to study the change of the secondary moment of unbonded prestressed concrete continuous beams and it has been contrasted with bonded prestressed beams. The question, whether the secondary moment changes or not while loading, was answered. It shows that the primary secondary moment does not change when increment method is adopted to study the beams, but the total secondary moment will change while the force in prestressed reinforcement changes.     

Finite Element Analyses of Spherical Node of Coal Pipeline System of Blast Furnace

The mechanical model of spherical node of coal pipelines of blast furnace is built. Its boundary conditions and loads are presented. Its finite element analyses are used for this structure. Its stress distributing rules are obtained and the security of this structure is evaluated.     

我国棉花品种抗黄萎病鉴定存在的问题及对策

对１９９０～１９９６年通过省级审定的８４个棉花品种的黄萎病病指分析表明,大多数品种的病指与其实际抗病性不符。分析其原因认为,抗性鉴定的病圃及鉴定方法不规范,品种审定时对抗黄萎病性能无明确要求等所造成,为此提出解决问题的对策。     

366份小麦品种春化光周期基因型组成及其与生殖物候稳定性的关系

为探究国内小麦品种春化光周期基因的显隐性组成及其与生殖物候稳定性的关系,以国内各大麦区主栽小麦品种及近几年的区试品系共366份为材料,采用STS标记对春化基因Vrn-A1、Vrn-B1、VrnD1、Vrn-B3和光周期基因Ppd-D1进行检测;同时采用分期播种法,以不同播期之间的抽穗期相差天数为生殖物候稳定性的评价指标,探索春化、光周期基因型对生殖物候稳定性的影响。结果表明,366份材料中包含15种春化光周期基因型组合,其中组合vrn-A1+vrn-B1+vrn-D1+Ppd-D1a最多,达48.91%,其次为vrn-A1+vrn-B1+Vrn-D1+Ppd-D1a,占16.39%。vrn-A1+vrn-B1+vrn-D1+Ppd-D1a能最大程度地维持小麦生殖物候稳定性,使抽穗期差异维持在5.43d,而vrn-A1+vrn-B1+Vrn-D1+Ppd-D1b、vrn-A1+Vrn-B1+Vrn-D1+Ppd-D1a、Vrn-A1+vrn-B1+Vrn-D1+Ppd-D1b则赋予小麦极不稳定的生殖物候特性,使抽穗期差异达10d以上。此外,显性春化基因能降低小麦生殖物候稳定性,其效应表现为Vrn-A1Vrn-B1VrnD1;隐性春化基因能够增强小麦生殖物候稳定性,其效应为vrn-B1vrn-D1vrn-A1;光周期基因对生殖物候稳定性影响不显著。     

小麦抗病基因Lr68和Sr2/Yr30的遗传特性分析

为深入了解小麦抗病基因的遗传规律,以亲缘关系较远的小麦品种西农979和RL6077为亲本,构建其BC1F1和F2群体,用特异性标记csGS和WMS533分别对抗叶锈病基因Lr68、抗秆锈病和条锈病基因Sr2/Yr30进行检测,同时进行农艺性状分析。结果表明,后代群体抗病基因分布广泛,F2群体抗病基因传递率(65.41%、74.53%、48.91%)较BC1F1(44.27%、55.11%、23.66%)高,Lr68基因在两群体中的传递频率均比理论值低,不符合一对显性基因的遗传规律,Sr2/Yr30基因在BC1F1中的传递率比理论值高,在F2群体中正常,且后代群体中Sr2/Yr30基因的分布较广。后代群体在有效分蘖数、株高、穗粒数、千粒重等农艺性状上与西农979无显著差异,有效小穗数与RL6077一致,茎部指标处于两亲本之间。总体来看,后代群体保留了西农979分蘖力较强、成穗率较高、穗型中等偏大、产量稳定等优良性状,且在分蘖数、成穗率、穗粒数上还有进一步提升的空间。     

Biomass Catalytic Pyrolysis with Ni Based Catalyst to Produce Hydrogen Rich Gas

Hydrogen rich gas was produced using rice husk as biomass material on the continuous biomass pyrolysis apparatus which consisted of continuous pyrolysis reactor and secondary catalytic cracking reactor. Ni based catalysts of different Ni/Al mass ratio and calcined temperature were prepared by impregnating method. The catalysts were characterized by X-ray diffraction (XRD), scan electron microscope (SEM) and FT-IR Spectrometer (FT-IR). Ni based catalyst showed good selectivity for H2 production from biomass. Catalysts prepared under different conditions had little influence on the yields of three states products when used at the same cracking temperature. Ni/Al mass ratio played an important role in products selectivity. However, the content of NiO increased further when Ni/Al mass ratio values reached 0.7 : 10, and the yield of H2 slightly increased. Hydrogen yield was greatly impacted by calcined temperature. Catalyst calcined at 550℃ performed best. When the catalyst was calcined at high temperature, NiO in the catalyst transformed into NiAl2O4, and the acid site also changed, which caused the deactivation of the catalyst. The hydrogen yield increased with the cracking temperature. The highest stable yield of hydrogen was about 30% without increasing with the cracking temperature.     

棉花气吸滚筒式穴播器二次投种机构设计与试验

针对棉花气吸滚筒式穴播器因投种性能不稳定而造成排种质量下降的问题,在气吸滚筒式穴播器的取种盘和鸭嘴之间增设二次投种机构,通过重新规划种子运动路径,降低投种点高度,减少了漏播和重播现象,提高了气吸滚筒式穴播器的排种性能。在保证气吸滚筒式穴播器取种方式不变的前提下,依次对二次投种机构的安装位置、种道轮廓和出入口的结构参数进行设计和分析,并采用离散元法对种子运动轨迹、运动速度和排种性能进行了仿真,阐明了漏播和重播产生机理。以合格指数、漏播指数和重播指数为评价指标,进行了三因素二次旋转正交组合试验,分析了安装角、作业速度、内种道高度对排种性能的影响。结果表明：安装角对合格指数的影响最大,内种道高度对合格指数的影响最小;当安装角为10.95°、作业速度为3.29km/h、内种道高度为16.68mm时,排种性能最佳,此时合格指数为98.40%,漏播指数为0.85%,重播指数为0.75%。田间试验表明：优化后二次投种机构的气吸滚筒式穴播器的合格指数为98.06%,较普通穴播器提升2.21个百分点。     

黄河中游输沙与减沙的时空分异特征

利用黄河中游主要水文站输沙量数据和48个雨量站降雨数据,分析了黄河中游1955年以来输沙与减沙特征,以及降雨与人类活动对输沙量变化的影响.结果表明:1955-2007年黄河中游输沙量总体呈下降趋势,20世纪70年代后较70年代前减沙46.8%,其中减幅较大的有汾河99.8%、岚漪河73.9%、州川河71.9%、三川河70.3%;退耕还林还草时期(1998-2007年)输沙量下降趋势最为明显,较70年代前减沙74.2%,除黄浦川,孤山川、佳芦河、屈产河、清涧河、延水之外,黄河中游大多数流域达到轻度侵蚀及以下;降雨因素和人类活动对输沙量变化的贡献率分别为37.6%和62.4%.