Pollen Source Influences Fruit Quality,Aril Properties,and Seed Characteristics in Pomegranate

A study was conducted to determine the effect of pollen source on fruit, aril, and seed characteristics in pomegranate. The cultivar Malas Yazdi was pollinated with three pollen sources including: Rabab Neyriz (a commercial cultivar), Malas Pishva Varamin (selected superior local cultivar), and Poost Sefid Dezful (non-commercial cultivar). The results showed that the rate of fruit set from different pollen sources varied from 13% to 46%. Pollen source also had significant effects on other fruit properties, such as fruit weight, fruit shape, fruit length and diameter, fruit peel color, fruit peel thickness, and edible portion of the fruit. Aril characteristics including number of arils per fruit, aril length and diameter, aril weight, and aril color were also significantly affected by pollen source as well as seed physical properties, including seed weight, seed length and diameter, seed hardness, and seed toughness. However ‘Malas Pishva Varamin’ as a pollinizer showed the lowest rate of fruit set, but performed better in terms of fruit quality and seed characteristic than ‘Rabab Neyriz’ and ‘Poost Sefid Dezful’. This is the first observation of xenia effect in pomegranate breeding and could serve as a new area of research for pomegranate production. These findings suggest that selection of suitable pollinizer could be a new area of research for pomegranate production.     

线弹性断裂力学原理在木材中应用的特殊性与木材顺纹理断裂

阐述了线弹性断裂力学 (LEFM)的原理以及在木材中应用的特殊性 ,并以杉木和马尾松为研究对象 ,采用不同试样和方法测定了木材的顺纹断裂韧性KTLIC 。研究表明 ,建立在各向同性体之上的LEFM原理对木材裂纹顺纹扩张是适用的 ,其顺纹断裂韧性是木材的固有属性     

DETERMING THE RELIABILITY OF A MEMBER WITH CRACK ACCORDING TO THE INFORMATION FROM FLAW-DETECTION WITH ULTRASONIC WAVE

Using the flaw-detecting with ultrasonic wave one may know the equivalant area of a crack that burys in the member. If the crack is ellipse shaped, the equivalant area is constant, and the distribution function of its major semiaxle and the plane strain fracture toughness of the material are given, then we would get the probability of reliability of the member under the uniform tension. In this condition, a formula of calculating the probability would be provided in this paper. Because a simple and enough precise approximate function has been introduced the formula in the paper is simple in shape and easy to use.     

长输管道的韧性设计

为保证长输管道系统的安全可靠，韧性设计是管道设计的重要指标，足够的韧性可以延缓或阻止断裂事件的进程。管道韧性设计基本出发点是安全性和经济性，综合平衡这两方面因素，并在断裂力学的基础上，提出了管道韧性设计的基本原则，即开裂控制原则，裂纹扩展的止裂原则和封口形原则。开裂控制原则提出了根据ＣＶ与钢管全壁厚临界缺陷尺寸的关系曲线，来确定相应管道对于开裂控制的韧性设计要求；裂纹扩展的止裂原则是根据Ｗ．Ａ．ｍ     

木工刀具的显微组织与性能

木工刀具性能与其显微组织关系密切．显微组织组成物晶粒细小，形状圆正，分布均匀，均有利于刀具获得优良性能，当刀具性能要求强调高硬度与适当韧性配合时，尤应避免晶粒粗大以及微裂纹等显微组织缺陷；当刀具性能要求突出高硬度和耐磨性时，其显微组织中硬化相相对量要多，并力避出现软组织等显微组织缺陷．     

柔度法标定木材断裂韧性的研究

本文应用柔度法测量了杉木的断裂韧性，研究表明：（１）柔度法是一种有效可行的实验标定方法，选用指数函数Ｃ=aexp(βa/w)能够很好地表达柔度与裂纹长度间的关系，（２）本文实验测定的杉木断裂韧性ＫIC=4.825MPa.mm^1/2.     

断裂力学在钢筋混凝土设计中的应用

混凝土是非均质材材,内部存在裂缝,所以其断裂破坏过程是复杂的.试验研究表明断裂韧性K_(lc)可以反映有裂缝材材的断裂性能,并在一定程度上决定混凝土构件的断裂过程.笔者试图从这一观点出发,阐明钢筋混凝土构件的断裂和抗裂荷载计算一法.     

Fe-Cr-C-V等离子堆焊层改善旋耕刀耐磨性和冲击韧性

为解决农机触土部件耐磨性差、失效频繁等问题,该文采用等离子堆焊技术在65Mn钢基体上制备Fe-Cr-C-V堆焊层;利用金相显微镜、X射线衍射仪分析了堆焊层的显微组织和物相构成;利用显微硬度计、往复式摩擦磨损试验机、自制土槽磨损试验机、冲击试验机等设备测试了堆焊层的显微硬度、耐磨性及冲击韧性。结果表明,堆焊层与基体呈良好的冶金结合,Fe-Cr-C-V堆焊层主要由α-Fe、Cr7C3、M7C3([Fe,Cr]7C3)、Fe-Cr固溶体、VC等组成。与65Mn淬火钢相比,Fe-Cr-C-V堆焊层的维氏硬度提高了75%,磨损质量降低了约67%。与Fe-Cr-C堆焊层相比,Fe-Cr-C-V堆焊层维氏硬度提高了HV0.5100,冲击韧性提高了21%。与常用的65Mn铲尖相比,有Fe-Cr-C-V堆焊层的深松铲铲尖磨损质量减少了78%,与常用60Si2Mn旋耕刀相比,有Fe-Cr-C-V堆焊层的旋耕刀平均磨损质量减小约50%。该研究可为延长旋耕刀使用寿命提供参考。     

Tensile fracture properties of seven tropical grasses at different phenological stages

The intake of forage grasses by grazing ruminants is closely related to the mechanical fracture properties of grasses. The relationship between the tensile fracture properties of grasses and foraging behaviour is of particular importance in tropical reproductive swards composed of both stems and leaves. This study (i) quantified and compared the tensile fracture properties of stems and leaves of seven tropical grass species and (ii) provided insight into the underlying plant traits that explain differences in fracture properties between species. Fracture force, tensile strength, fracture energy and toughness of stems (in various phenological stages) and leaves were measured and compared among five introduced tropical grasses (Cenchrus ciliaris, Chloris gayana, Digitaria milanjiana, Megathyrsus maximus (syn. Panicum maximum), Setaria sphacelata) and two native tropical grasses (Setaria surgens and Dichanthium sericeum). Species differed significantly in fracture force and fracture energy, with stems and leaves of C. ciliaris and S. surgens requiring less force and energy to fracture and stems and leaves of M. maximus and S. sphacelata requiring more force and energy to fracture in comparison with the other species. Differences in tensile strength and toughness were less pronounced. The differences among species in fracture force and energy mainly resulted from differences in cross‐sectional area of plant parts rather than from differences in tensile strength and toughness.     

Adding Polypropylene Fiber to Pavement Concrete and its Influence on Shock Resistance Toughness

选用海藻酸钠、明胶、壳聚糖、硬脂酸等原料作为涂膜对袖珍黄瓜进行涂膜处理,分别对袖珍黄瓜的失重率、呼吸强度、烂果率、叶绿素含量、硬度及可溶性固形物进行了测定。试验结果表明,第一层为海藻酸钠瑚胶（1％／0．3％）第二层为硬脂西垒,色拉油（1g/2mL）的两层膜保鲜效果最好,能抑制袖珍黄瓜的呼吸作用,阻止可溶性固形物的分解。