共查询到20条相似文献，搜索用时 15 毫秒
1.
This paper discusses the Reissner's plates on elastic foundation.The elastic foundation is considered as two- paramerer and its effect to thick plates are taken into account by a set of govering differential equations. According to the foundamental solutions for bending problem on two- parameter foundation derived, three boundary integral equations denoted by generalized displacement functions are established. This method is suitable to solve the bending problem of thin or thick plates on two- parameter foundation with arbitary boundary condition, arbitary shape and arbitary load conditions 相似文献
2.
Tunnel portal section mostly faces unfavorable geologic and topographical conditions, such as broken surrounding rock, shallow and unsymmetrical loadings. The current Chinese code for design of road tunnel provides the load calculation method of tunnel under unsymmetrical. However, according to the mechanic and deformation characteristics of the tunnel lining on site, the assumption is not suitable for the shallow tunnel under unsymmetrical loadings in broken surrounding rock. Therefore, through engineering case analysis and results of three-dimensional numerical analysis, the failure mechanism of shallow tunnel under unsymmetrical loadings in broken surrounding rock is presented firstly, that is, deep buried side broken surrounding rocks slump down after excavation and squeeze the lining, which makes the lining deform outward and bear passive earth pressure. Through the failure mechanism, the surrounding rock mainly includes slumping area and passive area. Then the corresponding formulas are deduced based on limit equilibrium theory. Finally, a case study is adopted to verify the feasibility of the new method. It is show that the new method is more reasonable than the method of current code. 相似文献
3.
页岩烧结保温砌块砌体基本力学性能试验研究 总被引：1，自引：0，他引：1
通过对页岩烧结保温砌块砌体轴心抗压、沿通缝抗剪、剪压复合抗剪性能试验研究,分析其破坏特征和破坏机理。试验结果表明:页岩烧结保温砌块砌体受压破坏时,在竖向灰缝附近形成主裂缝,接近极限荷载时砌体出现表皮剥落现象;沿通缝抗剪破坏模式主要为单剪破坏,脆性明显;剪压破坏有剪磨、剪压和斜压3种类型;实测轴心抗压强度平均值高于规范值,沿通缝抗剪强度、复合抗剪强度平均值低于计算值,并分别给出砌体轴心抗压强度平均值、抗剪、剪压复合受力抗剪强度平均值建议公式;剪压复合抗剪强度随着压应力的增大而增大;建立了页岩烧结保温砌块砌体受压应力应变关系表达式;给出该类砌块的弹性模量和泊松比的建议值。 相似文献
4.
Zhang Jianhui Deng Anfu 《保鲜与加工》1999,(2):84
The application of the element-free method in the bending problems of plates has not been found since it was proposed.In this paper,the element-free method is applied to compute the deflection and the moment of the elastic foundation plate with free boundary,and the corresponding formulas as well as the computer program are developed.Numerical examples show that the accuracy of the method used in the foundation plate problem is satisfactory.Therefore,it is reasonable and feasible for using the element-free method in the plate bending problems. 相似文献
5.
Compared with column bored pile,the bored pile with branches and plates is a new type of piles with higher bearing capacity and lower settlement.Field comparative tests related to ultimate bearing capacity of both the bored piles with branches and plates and column bored piles at the same site in Huzhou city of province Zhejiang in China were studied through self-balanced method under static pressure.The results testify that,compared with column bored pile under the same geological conditions,the bored pile with branches and plates can obtain better economic benefit such as: increasing ultimate compressive bearing capacity and ultimate extraction bearing capacity used per cubic meter concrete over 75.3%and 118.9%respectively,while dropping consumption of reinforced concrete upwards of 41.9%and 44.1% respectively,reducing settlement and pile length under the same loading.The tests will present an objective reference to the new type of piles in both theoretic study and application to analogous engineering. 相似文献
6.
The mechnical characteristics of concrete is sensitive to the strain rate and it is crucial to consider the effect of load rates on the behavior of reinforced concrete (RC) structures subjected to dynamic loads such as severe earthquakes. In this study, numerical simulations on the dynamic behavior of typical RC column specimens under dynamic loadings with different load rates were performed. Concrete constitutive model considering the strain rate effects proposed by the CEB code was employed with a fiber model to characterize the nonlinear strain rate dependent behavior of RC columns. The developed dynamic fiber element model was validated by comparing the simulated results of four RC column specimens with the fast loading test results. Results show that the developed fiber element model can predict the behavior of RC columns with acceptable accuracy. After valiating the proposed fiber elemen model considering the strain rate effect, the load carrying capacity of different RC columns with various longitudinal reinforcement ratios and volumetric stirrup ratios were simulated. Results show that the trends of the influences of longitudinal reinforcement ratios and volumetric stirrup ratios on the load carrying capacity of the RC columns under dynamic loadings are different. 相似文献
7.
Cereal production systems are increasingly threatened by suboptimal water supply or intermittent drought spells early in the planting season. Seed coated with hydrophilic materials or hydro‐absorbers that increase the amount of water available for germination and seedling development is a promising approach to improving stand establishment under changing conditions. Barley, rye and wheat grains with combinations of hydro‐absorber, humic acid and Biplantol® in different shares of the total seed mass were germinated in plates at 25 °C on moist filter paper. Germination rates, resource partitioning and mobilization efficiency were assessed and compared with those of uncoated seeds. Results show a strong influence of coat thickness and composition on the germination rate and the efficiency of mobilization of carbohydrates stored in the endosperm. In general, coating significantly reduced germination rate and total germination as compared to uncoated seeds in all cereals tested. Differences in coating thickness had a distinct effect on germination rate for most combinations of coatings and species. Germination rates increased with increasing coat size. This effect was most pronounced for coatings containing hydro‐absorbers and least pronounced for coatings containing humic acid or Biplantol®. Coating generally increased the amount of carbohydrates partitioned to the roots, and thick coating increased the efficiency of grain reserve mobilization compared with the uncoated seeds. Differences between species and the implications for coating‐related changes in germination metabolism are discussed. 相似文献
8.
施肥对不同苜蓿品种粗蛋白含量的影响 总被引：1，自引：0，他引：1
SHEN Chuan-jin WANG-Jun FAN-Fu Wuhai Institute of Agricultural Science in Inner Mongolia Wuhai China Agricultural College Inner Mongol University for NationaIities Tongliao China 《华北农学报》2006,(Z3)
为提高苜蓿的品质及饲用价值,试验分析了不同施肥(N,P,K)对加拿大苜蓿阿尔冈金、美国苜蓿WL232HQ、敖汉苜蓿粗蛋白含量的影响,以及不同施肥制度下、不同苜蓿品种之间粗蛋白含量的差异。分析结果表明:美国苜蓿WL232HQ粗蛋白含量最高为22.20%、加拿大苜蓿阿尔冈金粗蛋白含量最高为21.863%,敖汉苜蓿粗蛋白含量最高为20.098%,其对应的施肥方案为尿素60.33kg/hm2、过磷酸钙90.78kg/hm2、硫酸钾132.00kg/hm2,并得知美国苜蓿WL232HQ在同一施肥条件下粗蛋白含量较其他品种高。 相似文献
9.
S. Reed T. Ayala‐Silva S. Brown B. Glaz J. Comstock 《Journal of Agronomy and Crop Science》2012,198(3):236-244
This study evaluated the biomass production potential of Saccharum barberi (Jeswiet) and Saccharum sinense (Roxb. Amend. Jeswiet) accessions under short‐term flooded conditions. Plots were arranged in a completely randomized design with 20 S. sinense and 29 S. barberi accessions, two flood durations with non‐flooded controls and three replications of each treatment. There were no significant flood effects. However, in two individual accessions, ‘China’ and ‘Lu Cane’, sucrose production increased with additional flooding. The plant cane produced larger plants with a greater percentage of fibre and sucrose. Higher Brix values were obtained with the ratoon crop. Brix and fibre were negatively correlated with stem diameter. Stem length in S. barberi was the only physical characteristic that was correlated with sugar factors Brix and optical rotation. S. barberi accessions had high loadings for variables associated with sugar production and stem length, and fibre had moderate loadings for factor 1. Factor 1 explained 35 % of variance in the data. The second principal factor revealed high loadings for variables associated with plant size. Factor 2 explained 30 % of the proportional and together with Factor 1 explained 65 % of the cumulative variance in the data. Several accessions with low sucrose, high plot weight and low fibre were identified. These accessions make attractive selections in breeding for biomass production. 相似文献
10.
The hydraulic loading and wet/dry(W/D) ratio,which are two important indexes in the constructed rapid infiltration,can affect the removal effect.Presently,the domestic experimental reports about the hydraulic loading and(W/D) ratio aiming at the Three-Gorges Reservoir Region is rather scarce.This article studies some pertinent hydraulic loadings and W/D ratios suitable for the Region.The authors emphatically research the effect of CRI treating COD,TN and TP in the sewage under four hydraulic loadings and three different W/D ratios.It is suggested that when the temperature is ascending,the W/D ratio can be risen to some extent.The variations of loading and ratio can affect the COD,TP removal effect a little,but affect the TN removal effect much.The experimental conclusions can provide evidence to the application of constructed rapid infiltration in the Three-Gorges Reservoir Region. 相似文献
11.
This paper presents a mathematical and mechanic model for non-linear dynamicstability analysis of structures on the basis of Liapunov's stability criteria. Due to the complexityand difficulty in numerical calculation,a matrix function to this type of stability problems is selectedand the programing formulations are derived.Applying the method to beam or frame structures un-der the axial period loadings,the geometric non-linear dynamic stability results are obtained.Fromthe results,the basic characteristics of this type of probtems,especially the non-linear effect areshown.The model and matrix function method are valtiable both in theory and in practice for struc-tural non-linear dynamic stability. 相似文献
12.
Improving white clover drought tolerance by selecting for more developed roots is controversial, labour‐consuming and complicated by the adventitious root system. This study aimed at assessing: (i) the value of thicker stolons as an indirect selection criterion for increasing root development, (ii) the relationship between root development and drought tolerance, and (iii) the consistency of population response for root and shoot traits between swards derived from seedlings or stolon cuttings. Thick‐ and thin‐stolon populations obtained by one cycle of divergent phenotypic selection within one ladino landrace, and one ladino natural population, were evaluated in metal containers (0.55 m × 0.12 m × 0.75 m deep) in a 1‐year experiment including vegetative material (seedling or stolon cutting) and drought stress (absent or present) as additional factors. Aerial dry weight (DW) was also assessed across two summer harvests under irrigated and rainfed field conditions for the thick‐stolon selection, two breeding populations selected from the same landrace regardless of stolon thickness, and the drought‐tolerant ladino ‘Brown Loam Synthetic no. 2’. The thick‐stolon selection had greater root DW (+21 %) than the thin‐stolon selection besides thicker stolons (+23 %). The natural population combined thinnest stolons with lowest root DW. Differences between populations were consistent across vegetative material. Primary and adventitious root systems did not differ for root DW in deeper soil horizons (>23 cm), above‐ground biomass and its reduction due to drought stress. Root DW increased under stress, particularly in deeper horizons. Aerial DW variation among populations evened up or narrowed much under stress, with no cross‐over interaction leading to an advantage of thick‐stolon material or ‘Brown‐Loam Synthetic no. 2’. 相似文献
13.
本研究主要对新引进的日光温室与当前厚墙体温室的光热性能进行对比研究,为呼和浩特地区日光温室的建设提供参考依据.根据4种类型日光温室小气候监测数据,分析温室内外日平均温度、温室内外日最低温度、温室内外日最高温度、温室内光照度等气象要素变化规律.双膜双被日光温室为室内温度水平最高的日光温室,越冬期间(1月12日-2月21日... 相似文献
14.
Zhang Peiyuan Yan Po Jiang Han 《保鲜与加工》1995,(5):20-24
Authors approach problems of anti-plane deformation in honeycomb plates by using model of polar material in which exist couple stresses. Equivalent constitutive equations are introduced in the paper and equivalent couple stresses are contained in it. It shows that in analysis of one-dimensional problem of statics the relationship of stresses to torsions and of couple stresses to strains may be negligible and this neglect simplifies analysis of problems. 相似文献
15.
By using mixed triangle series,this paper discusses the calculation of rectangular stiffened plates with simply supported edge along direction of stiffeners under several local loads,such as uniform load on local rectangular area,concentrated force,concentrated moment of couple,line loads,line moments of equal and some equivalent concentrated forces acting on a line with equaldistance among them.All analytical solutions of both displacements and internal forces are derived.A numerical example to treat an engineering problem is given. 相似文献
16.
This paper solves the geometrically nonlinear problems of symmetric, cross-ply laminated anisotropic rectangular plates subjected to uniformly distributed load by the higher-order shear deformation theory and taking an advantage of the perturbation and the weightedresidual method. First, with the help of the perturbation, the nonlinear partial equations have been changed into linear ones. This paper can solve these linear ones by the weighted-residual method. The combination of quintic B-spline functions are chosen as the basis of trial function and Dirac delta functtion, the weighted function. The method used in this paper is simple, direct and efficient. The numerical results show a good convergence and they are in good agreement with the available data. 相似文献
17.
By adopting the energy and finite-element methods with analysis software MATLAB and ANSYS,a detailed and complete solution process for bucking of simply supported rectangular elastic plates is provided.By increasing the triangular series for the deflection function,the amendments have been made to the K values given in references.Through finite element analysis,the expression of K value is fitted out.It is ascertained that the shear stress,taken as a critical shear stress,is reasonable according to the small deflection theory under limited plate deflection.The results of two analytical methods show that the fitting curve of K values used by finite element analysis has more comprehensive practical significance. 相似文献
18.
一个新的拟南芥磷饥饿反应突变体筛选体系 总被引：1，自引：0，他引：1
磷是植物必需的一种大量营养元素。农作物的产量经常因磷饥饿而受损。研究植物在磷饥饿条件下所发生的变化,有利于以后运用基因工程的手段培育耐低磷农作物。将野生型拟南芥与磷饥饿反应突变体进行对比研究,能够为植物对磷饥饿反应的研究提供重要线索。筛选植物对磷饥饿反应突变体,筛选方法是非常重要的。野生型拟南芥在供磷正常的培养基上竖直培养时主根向下,同时呈较大幅度的弯曲。在磷饥饿的培养基上主根则几乎是垂直向下的,而且主根相对较为短小。利用这种现象,在供磷正常的培养基上种植的拟南芥植株中发现了一株可能的新的磷饥饿反应突变体。 相似文献
19.
粘虫色板防治菇蚊菇蝇的研究 总被引：1，自引：0，他引：1
为了给粘虫色板在食用菌害虫防治中的应用技术方案制定提供科学的依据,进行了对5种不同颜色的粘虫色板对菇蚊菇蝇的诱杀效果比较研究,进一步对粘虫色板的悬挂高度、悬挂密度、悬挂时间以及在菇房中应用粘虫色板的防效果和对食用菌产量的影响评价等方面研究。研究结果表明不同颜色的粘虫色板对食用菌菇蚊菇蝇的诱杀效果有显著差异,其中黄色粘虫色板对菇蚊菇蝇诱杀效果最佳;利用黄色粘虫色板悬挂在菇房中菌墙的上方30cm左右,晚间结合灯光诱杀效果最佳;处理菇房的菌袋受害率降低了14.7%,挽回产量损失达11.0%,防治效果显著。 相似文献
20.
番木瓜酸奶除具有普通酸奶的生物学价值外,还有番木瓜特殊的芳香,且果料的添加使酸乳制品更易消化吸收、更富色香味、更具吸引力。以优质奶粉与成熟的番木瓜为原料,以保加利亚乳杆菌和嗜热链球菌1∶1混合为发酵剂,在均质、杀菌、冷却后加入发酵剂进行液态发酵生产番木瓜酸奶。在相同的稳定剂条件下,以不同的番木瓜浆添加量、蔗糖用量、发酵时间、发酵剂的接种量进行发酵的正交试验,对产品进行感观评价,以此来确定最佳的工艺参数及配比,为番木瓜酸奶最佳生产工艺的研究提供依据。结果表明,采用保加利亚杆菌和嗜热链球菌(1∶1)混合菌为发酵菌种,取番木瓜浆与牛奶的体积比2∶3,蔗糖用量20 g,发酵时间4 h,发酵剂的接种量6 mL,加糖量为10%,稳定剂CMC 0.02%,发酵温度为42℃,以此工艺条件制备的番木瓜酸奶,具有独特的风味和较高的营养价值。 相似文献