Modulation Transfer Function of Image Monitoring System for Bridge''s Deformation

The principles of image monitoring system for bridge's deformation is proposed. Based on linear system theory, the whole system comprises linear shift-invariant system composed of atmosphere, optical sub-system and camera. The modulation transfer function of each component is analyzed, especially for the atmosphere. For a special system, modulation transfer functions on different weather condition such as sunny, cloudy, rainy and fogy weather are analyzed.     

山区旱地高低垄宽窄行栽培对土壤化学性状及烟叶产质量影响

通过大田试验研究高低垄宽窄行栽培对烟叶产质量及土壤化学性状的影响。结果表明:高低垄宽窄行栽培能显著提高土壤碱解氮含量10%(P=0.1184),提高土壤速效钾含量,降低土壤p H,有降低土壤有机质含量趋势,对土壤速效磷含量影响较小;能提高烤烟叶绿素含量,近似显著地提高烟叶产量5%(P=0.0524),显著地提高烟叶产值10%(P=0.0952),对烟叶均价与上等烟叶比例影响较小;它主要影响B_2F的化学成分;能提高B_2F与C_3F烟叶的劲头、浓度、香气质、香气量与余味等评吸质量。     

Creation of an Experimental System for Testing the Dynamic Tensile Stress of Cells Using Membrane Variable Stress Wave

The constitution, design ideas and working principles of the DDC experimental system for testing dynamic tensile stress of outside body cell using membrane variable stress wave are discussed in detail. A new design measure is put forward, i.e. using airtight liquid for transferring pressure, and a space mechanism which is made up of two moveable linking axes and controlled by DDC for producing dynamic tensile stress with variable stress wave. The space mechanism is made up of two moveable linking axes, the first axis is controlled by an alternative current servo system, at the same time it drives the modulating modulating disc, and its rotation velocity is uniform and adjustable, so the rotating velocity of the disc can be controlled. Second, the hydraulic pressure worktable is driven by step electric motor. By dynamically changing the relative position of the modulating disc and the worktable, the journey of the piston in hydraulic pressure vat can be changed accordingly. The resultant motion of the modulating disc rotation and the radial direction relative movement of the piston can create liquid pressure with variable frequency and amplitude range, and the pressure can be changed into membrane tensile stress with variable frequency and pressure amplitude range using pressure fine tuning, and muhi-path disporting pressure. The system is proved to be simple, reliable, economic and controlled expediently by the experiment conducted.     

Evaluation of Barley (Hordeum vulgare L.) Landrace Populations Originating from Different Growing Regions in the Near East*

This study characterizes barley (Hordcttm vulgare L.) garmplasm that evolved under continuous cultivation in highly drought-prone areas of the Near East. Landrace population:) originating from 70 locations in Syria and Jordan were evaluated under field conditions in Tel Hadia, Svria, on the basis of single head-row progeny performance. Significant genetic variation was found for all traits recorded: seed colour, kernel row number, growth habit, awn barbing, days to heading, culm length, leaf widths, awn length, early growth vigour, lodging score, and mildew resistance. For most traits, large proportions oi the total variation were tound between head progenies tvhh.in single populations. The qualitative traits, growth haba, seed colour, and awn barbing showed higher variation indices in populations originating from the drier regions ol Syria. Populanons from tbe drier regions; headed slightly earlier, had narrower leaves, longer eulms and tended to be more susceptible to lodging and mildew than populations originating in the higher rainfall areas in Syria. For all traits, the variance components resulting from differences among populations within a particular growing region, as well as those among populations from differences regions, were highly significant. This indicates that this germplasm stock contains materials with adaptability to these diverse growing conditions. The vanabili:y present within populations, as well 25 that among populations with similar adaptability, is sufficient to allow successful election for productivity-related traits.     

A SELF-TUNING CONTROL FOR A PARALLEL AC/DC POWER SYSTEM

Based on a non-linear system model, an adaptive control methodology is presented for a parallel AC/DC power system by means of on-line recursive parameter identifications. Taking the advantage of rapid power regulatiing ability of the DC power system and combining with the generalized minimum variance self-tuning control principles, the dynamic qualities of the controlled system has been greatly improved. Using SISO form makes the control system very simple to implement. Through the design, simulation and analysis of the self-tuning control system for a practical example, it shows that the self-tuning control strategy is very promising for AC/DC power systems.     

Finite element analysis of bending stiffness for cross-laminated timber with varying board width

ABSTRACT

Cross laminated timber (CLT) is a wood panelling building system that is used in construction, e.g. for floors, walls and beams. Because of the increased use of CLT, it is important to have accurate simulation models. CLT systems are simulated with one-dimensional and two-dimensional (2D) methods because they are fast and deliver practical results. However, because non-edge-glued panels cannot be modelled under 2D, these results may differ from more accurate calculations in three dimensions (3D). In this investigation, CLT panels with different width-to-thickness ratios for the boards have been simulated using the finite element method. The size of the CLT-panels was 3.0 m × 3.9 m and they had three and five laminate layers oriented 0°–90°–0° and 0°–90°–0°–90°–0°. The thicknesses of the boards were 33.33, 40.0, and 46.5?mm. The CLT panel deformation was compared by using a distributed out-of-plane load. Results showed that panels with narrow boards were less stiff than wide boards for the four-sided support setup. The results also showed that 2D models underestimate the displacement when compared to 3D models. By adjusting the stiffness factor k88, the 2D model displacement became more comparable to the 3D model.     

玉米株型和幅宽对套作大豆碳氮代谢及产量的影响

在玉/豆套作模式下,采用玉米株型与种植幅宽二因素裂区设计,研究了不同田间配置对套作大豆碳氮代谢与产量的影响。结果表明,较大幅宽和紧凑型玉米下,大豆被荫蔽的程度有所减缓,碳氮代谢变化趋势朝着利于产量形成的方向发展。主要表现为,茎叶中的碳氮含量和关健酶在各时期保持在较高的水平;R4期后叶片中的淀粉迅速降解为糖运至籽粒,而氮的下降速率缓慢。结合前期的研究,我们得出,R2是大豆经历光照转换的重要时期,该时期植株的碳氮代谢能力对大豆后期产量的形成起着重要的作用。而R6期大豆表现出来的碳、氮代谢水平,又能一定程度的反映产量水平。本试验条件下,对玉米、大豆两季作物的经济效益进行分析后得出,利于大豆生长,且保证全年高产,高效的最优组合为：与紧凑型玉米套作,大豆幅宽1.17m,玉米幅宽0.83m。     

水杨酸预处理提高铁线蕨冷胁迫的渗透调节反应

研究不同浓度水杨酸(SA)预处理下,铁线蕨(Adiantum Capillns-veneris)对冷胁迫的渗透调节反应,测定游离脯氨酸(Pro)、可溶性糖(WSS)、脱落酸(ABA)以及相对电导渗透率(RMP)的变化,结果表明:SA预处理降低了低温时游离Pro、WSS的含量,并降低RMP,增加了低温时ABA的含量。冷胁迫时外源SA通过提高铁线蕨渗透调节能力,以抵御冷胁迫逆境。     

果园开沟深度宽度监测装备设计与试验

针对开沟作业过程中作业深度、宽度依靠人工监测,存在人工工作量大、实时性低等问题,研制果园开沟深度宽度监测装备。通过设计果园开沟深度宽度监测平台,结合LabVIEW上位机人机交互系统与Arduino单片机下位机数据测量系统,最终完成果园开沟深度宽度监测装备的研制,实现开沟作业过程中开沟宽度、开沟深度、作业时间等参数的实时监测、计算、显示与保存等功能。试验结果表明,开沟深度为25 cm时,装备测量误差最大为3.1 cm;开沟深度为30 cm时,装备测量误差最大为2.7 cm;开沟深度为35 cm时,装备测量误差最大为3.7 cm;开沟宽度的测量误差最大为3.1 cm,能够满足实际应用需求,数据实时性较好,能够满足作业监测需求,为智能化果园开沟作业质量实时监测奠定一定的基础。     

侧柏植株体积、叶面积的量测及其与株高、冠幅的关系

为了研究侧柏(Ptadtyctadus orientates)植株体积、叶面积的量测,及与株高、冠幅、叶面积指数间的定量关系,进行了相关的盆栽试验。试验结果表明,随长方体、圆柱体体积的增大,实体体积均呈线性极显著正相关。随冠幅的增大,实体体积、总叶面积分别呈线性(R=0.572)和开口向下的抛物线(R=0.450)规律变化。当冠幅73cm,圆柱体侧面积0.546m2,圆柱体横截面积0.329m2时,总叶面积对应达最大值,分别为3 581,3 639,3 523cm2。随总叶面积的增大,叶体积、枝体积、实体体积呈开口向下的抛物线规律变化,均呈极显著相关关系。随叶体积的增大,叶面积指数呈开口向下的抛物线(R=0.742)规律变化,叶体积338cm3时,达最大值6.1。