Design Methods to Control Vibration of Solid Lumber Joist Floors

Timber floors are by far the most common structural systems used in wood-framed residential buildings,and are the only systems with which human occupants are in constant physical contact.In dwellings,the floor vibration due to walking often brings discomfort to the occupants.Designing a house that controls the agonizing vibration of floors is a difficult problem.The vibration performance of five solid wood lumber joist floors was studied as were subjective opinions of evaluators.The 1KN static deflection and fundamental natural frequency were selected as two evaluation indexes of the vibration performance.The results show that when the ratio of the fundamental natural frequency to 1KN static deflection's 0.44 power is larger than 20,the solid wood lumber joist floor can be classiified as acceptable.     

Dynamic Performance Analysis of Prestress Self balanced Cable Truss

As a new kind of supporting member, a prestress self balanced cable truss has been widely applied in point supported glass curtain walls. The free and forced vibration behaviors were analysed. Taking the temperature effect and geometric nonlinearity into consideration, the nonlinear vibration equation was derived with continua theory for prestress self balanced cable truss support system in point supported glass curtain wall. By the Galerkin method, the partial differential equation was transformed into ordinary differential equation and then solved with L P method and KBM method. With the case study, the effects of temperature, amplitude, and exterior excitation on the nonlinear vibration were discussed. And it was found that the frequency would decrease with increase of temperature and the nonlinear vibration showed the characteristics of hard spring.     

Experimental Analysis on Energy Dissipation Mechanism and Seismic Performance of Steel Truss Coupling Beam-Coupled Shear Wall Structure

Pseudo-dynamic tests and low cyclic reversed loading tests on two-floor coupled shear wall planar structures were conducted, and one is arranged with two steel truss coupling beams, the other is arranged with a steel coupling beam and a RC coupling beam. The shear walls’ seismic response under different earthquake intensity was deliberated, Their failure mechanism, bearing capacity, hysteretic ductility, energy dissipation mechanism, and stiffness and strength degradation mechanism were analyzed as well. The results show that the shear wall with two steel truss coupling beams has reasonable stiffness distribution. Its energy dissipation mechanism, stiffness and strength degradation mechanism can fulfill the demands of coupled shear wall’s seismic design: under rare earthquake, it can maintain good bearing capacity and stiffness, and keep restraining the walls. Its seismic performance is superior to RC coupling beams-coupled shear wall system.     

Steady state Heat Transfer Performance of Domestic Light frame Wood Wall

Steady state heat transfer performance is an important indicator for wood wall to assess its energy efficiency performance. Based on the introduction of foreign advanced technology of wood residence, 13 different wall specimens were manufactured using domestic materials in this study, and the effective heat transfer coefficient were measured by hot box heat flow meter test method. With the results from theoretical calculation, it was found that the effective heat transfer coefficient of walls were between 0.226～0.529 W/(m2· K). The thermal level was IIt for specimen 1,2,3, and 6, and level It was for the others, which could be appropriate for the severe cold areas and meet the requirements of 65% Energy efficiency standard in China. The calculation results were in good agreement with the measured ones.     

葵花秸木材代用品生产及开发前景研究

探讨了使用葵花秸生产木材代用品的开发价值及前景。在工艺技术方面,提出用葵花秸生产木材代用品的实施方案。对原材料收集加工、不同类型刨花的制备工艺过程及不同类型刨花对成品性能的影响等问题进行研究。     

Experimental Analysis on the Behavior of Panel-to-lumber NailedJoints in Light Wood Frame Construction

To study their resistance performance, totally 222 specimens of panel-to-lumber nailed joints, in different configurations and used in light wood frame construction, were manufactured and tested under monotonic load. There are five kinds of destruction produced with nailed joints,which are model M-c1, rupture of panel, shear failure of panel, wood tear-off and push-through of nail. The resistance of nailed joints with vertical nailing is higher than that with toe-nailing, while the stiffness is almost the same. The angle between the panel orientation and dimension lumber wood grain affects the resistance and the stiffness of nailed joints little, while the angle between loading and dimension lumber wood grain affects the stiffness but not the resistance. The empirical equations to calculate the stiffness of the nailed joints are derived, thus providing reference for evaluating the performance of shear walls and diaphragm (floor and roof) in design of light wood frame structures.     

杉木阻燃浸渍处理工艺的研究

采取木材浸渍处理工艺, 使用NH4H2PO4、BaCl2、MgCl2、硼砂、硼酸等阻燃剂对木材进行处理, 并对其阻燃效果进行了评价。发现NH4H2PO4、硼酸、硼砂阻燃体系通过浸渍处理工艺, 木材可以获得较好的阻燃效果。通过实验对NH4H2PO4、硼酸、硼砂阻燃体系处理木材的工艺条件进行了优化选择, 得到了最优工艺条件: 浸渍温度为80℃, 阻燃体系质量分数为20%, 在常压下浸泡12h。     

Impact Mechanism of Member Initial Stress on Space Truss

To reveal distribution characteristics of member initial stresses, nine experimental prototypes in span of 4 m, 5 m and 6 m were employed. To analyze effects of member initial stresses on ultimate capacity of space truss, a prototype in span of 6m was applied. Meanwhile, the results were compared with those of Abaqus nonlinear FEM which were based on elastic-perfectly plastic model and Marshall Mode. Initial stress test shows that some initial stresses approach or even exceed stability stress. It is shown that the test ultimate capacity decreases by 17.9% than that of Marshall Mode, and the safety margin of structure is just 1.25. The impact mechanism of member initial stress consists in damaging structure initial symmetry, producing member initial bending and prompting press member buckling in advance. Member initial stress must be taken into account when space truss design, especially Fully-Stress design, is conducted.     

速生人工林桉树木材高温热处理力学性能研究

广西速生人工林桉树资源丰富,对其进行高温热处理能够改善其极易端裂、尺寸稳定性和耐久性差等缺陷;同时,其力学性能受到一定影响。为此,采用单因素试验方法对高温热处理桉树木材的力学性能进行研究。主要探讨了热处理温度对速生桉树木材力学性能的影响。结果表明：热处理温度在180~230℃范围内,随着热处理温度的升高,木材的静曲强度、弹性模量随之降低,经220℃处理的桉木试件的静曲强度(MOR)、弹性模量(MOE)分别比未处理的降低了43.18%和35.94%。高温热处理对速生人工林桉树木材的改性效果显著,同时其力学性能有所降低。     

不同保果方式对串番茄品种果穗整齐度及产量的影响

研究了花序电动振动辅助授粉、PCPA蘸花处理及自然授粉对串番茄ST 02、ST 03、ST 04的果穗整齐度和产量的影响。结果表明,电动振动辅助授粉和蘸花处理较自然授粉明显提高了果穗的整齐度和产量,且蘸花处理的产量最高,操作最为便捷。     

A Study on Vibration Isolation for the Machine on Flexible Foundations

The problem of vibration isolation for the multi supporting machine installed on flexible foundations was studied by power flow and four end parameters methods.The general model of machine,isolator and flexible foundations was founded,and the transmission characteristic of the vibration system is analyzed.The expressions of power flow of the system with wave propagation effect being concerned was also presented.Finally,the effect of foundation flexibility and wave propagation on isolation was analyzed in detail.     

大豆基木材胶粘剂耐水性的研究

简要回顾了大豆基木材胶粘剂的发展状况,指出耐水性差和抗生物降解能力弱是限制豆胶继续发展的两大瓶颈问题。探索大豆基木材胶粘剂耐水性的形成机理,详细介绍了强化耐水性的几种可能方法。提出在不使蛋白过度水解的条件下,将大豆球蛋白中具有化学反应活性的官能团最充分地暴露出来,仿效大自然中耐水性蛋白结构形成的化学机理,提出了仿生强化改性法,为提高大豆胶耐水性和胶合强度提供了科学依据。     

银杏木醋液对作物种子发芽及幼苗生长的影响

采用气相色谱-质谱(GC-MS)联用技术分析了银杏木醋液的组成成分,研究了银杏木醋液对作物种子发芽及其幼苗生长的影响.研究结果表明:银杏木醋液是一种组成成分相当复杂的混合物,主要成分是水,其次是有机酸、酚类、醛类、酮类、酯类及其它杂环类物质等,其组分与采集时的炭化温度有关.银杏木醋液对作物种子的发芽及其生长都有显著影响,其影响大小因木醋液的浓度、采集时的炭化温度及作物种子而异.     

木酢液对几种类型蔬菜生长调节效应的影响

大棚种植了西红柿、辣椒、大白菜、黄瓜和萝卜等6种4类蔬菜。苗期时,喷施木酢液1000倍液;定植后,采用喷施200倍液、300倍液、400倍液、500倍液、600倍液等5个浓度处理,以此来分析施用木酢液对各类蔬菜产量、根长及株高的影响。结果表明：木酢液对不同类型的蔬菜都有一定的增产作用,但效果不一,300倍液适用面较广、200倍液对不同类型蔬菜都有生理毒害效应、600倍液对蔬菜的生长长势有明显的促进作用。总体看来,适宜浓度的木酢液能促进植株生长,提高蔬菜产量。     

木醋液浸种对西葫芦种子萌发和幼苗生长的影响

为研究木醋液浸种处理对西葫芦种子萌发和幼苗长势的影响,笔者广泛查阅相关资料,用100、300、500倍的稀释木醋液浸种6 h,并用同体积蒸馏水同时间浸种作为对照进行研究,调查分析在光照培养箱内种子萌发和幼苗生长的情况。结果表明：使用木醋液浸种,对于西葫芦的发芽势、发芽率、幼苗芽长、幼苗主根长、百苗鲜重、百苗干重,以及活力指数都有影响。使用不同浓度的木醋液浸种,对西葫芦种子各项发芽指标和幼苗长势的影响不同;使用100倍稀释木醋液浸种,幼苗长势形成最高峰值,活力指数比蒸馏水浸种的对照提高9.01%,鲜重、干重、主根长分别比对照增加13.47%、9.81%、15.79%,产生显著差异;使用100倍稀释木醋液浸种处理对发芽势有一定的促进作用,对芽长、发芽率、发芽指数影响不显著。说明木醋液浸种可促进根系生长、鲜重和干物质积累增加,提高活力指数,幼苗长势更强,可应用于西葫芦种子播前处理。     

甲酸和木醋液对苜蓿青贮细菌群落结构的影响

为探讨抑制型青贮添加剂对苜蓿青贮细菌群落结构的影响,以木醋液和甲酸为添加剂,按6 mL/kg的剂量与干物质含量为(23.02±0.70)%的苜蓿混匀制作青贮,以等量蒸馏水替换添加剂的处理作为对照,45天后运用高通量测序技术分析苜蓿青贮的细菌群落结构。结果表明,对照组以变形菌门(Proteobacteria)肠杆菌科(Enterobacteriaceae)未知属为优势,以厚壁菌门(Firmicutes)肠球菌属(Enterococcus)为次优势;木醋液组则以厚壁菌门肠球菌属为优势,以变形菌门肠杆菌科未知属为次优势;甲酸组以蓝藻细菌门链型植物目(Streptophyta）未知科属为优势。与对照组相比,苜蓿青贮中肠球菌属丰度在木醋液组显著提高而在甲酸组显著降低,木醋液和甲酸组均显著降低了肠杆菌科丰度且甲酸组降幅显著高于木醋液组;甲酸组显著提高了细菌群落丰富度指数(Chao1和ACE)但降低了优势度指数(Simpson)。主成分分析表明,苜蓿青贮细菌群落结构与其营养和发酵主要指标可解释苜蓿青贮88.786%的信息,在样品分布上,木醋液组居甲酸组和对照组之间但更趋向于对照组。综上,甲酸和木醋液均改善了苜蓿青贮细菌群落结构,其中甲酸主要是抑制菌群发酵,而木醋液则有助于促进乳酸菌发酵。     

杂种小麦源库基本特性的研究

对杂种小麦与普通小麦（包括杂种小麦亲本）的比较研究表明：杂种小麦在顶部二叶的光合速率高值持续期、累积蒸腾量、叶片功能持续期以及光全有效叶面积上显著优于普通小麦、叶源量高出30.22%。杂种小麦籽粒中内源生长素（IAA）、玉米素（Z）及玉米素核苷（ZR）含量在发育各时期均显著高于普通小麦。但杂种小麦的叶鞘、茎干重     

A Study of the Vertical Vibration of the 4200 Thick Plate Rolling Mills

In this paper,the mill stand and the rolled piece were studied as a system. Based on the disoreted masses and the deformation of bending curve of the roller and roll housing, according to Rayleigh method,the equivalent mass and and the equivalent stiffness of the mode were solved,and set up a multiple degree of freedom vibration dynamic model. And also did theoretical analysis and calculation with an exapmle of the 4200 thick plate rolling mills.     

Empirical Study on the Macroeconomic Performance of China''s FDI

The problem on performance of foreign direct investment is the heart of matters, which are further expanding foreign direct investment in China and strengthen international competitive ability of Chinese enterprises. The empirical study on macro performance shows that foreign direct investment in China has made no difference to economic growth and export promotion, both long term and shot term; for a long term, it has no remarkable effect on foreign exchange reserve, but remarkable and negative effect in a short term. It has no any effect on domestic investment in long or short term. There is no balance relation in long term and no cause and effect relation either between foreign direct investment and FDI inflow, or between foreign direct investment and total factor productivity. Foreign direct investment in China has no remarkable effect on macro performance.     

木醋液对元宝枫幼苗生长发育的影响

研究木醋液对元宝枫生长发育的影响,旨在确定适宜元宝枫萌发及幼苗生长的木醋液土施浓度,为元宝枫的高效栽培提供参考信息.在光照培养箱中培育元宝枫,通过土施稀释200、400、600、800倍的木醋液,以超纯水为对照,记录种子萌发及幼苗生长发育情况.试验结果表明,木醋液稀释800倍时对元宝枫的发芽率、幼苗鲜重、幼苗干重、叶片...