三维激光扫描技术对接种菌根植株形态的影响规律

三维激光扫描技术建立的植物三维立体模型,可精确、全面、原位地反映植物形态特征,对于揭示接菌植物的微观形态特性具有比传统测量方法更明显的优势。以玉米为供试材料,在低磷条件下(20 mg/kg),设置接种菌根与对照两个处理,研究三维激光扫描技术对接种丛枝菌根真菌的植株形态特征在不同生长期的动态变化规律,分析比较不同处理的植株侵染率、菌丝密度、土壤酸性磷酸酶活性和土壤有效磷等理化指标及玉米形态特征的变化。研究结果表明,在低磷条件下丛枝菌根在30 d时侵染率已经达到82%,菌丝密度增加,酸性磷酸酶活性增强。在生长到30 d的时候,接菌组的株高、冠幅分别比对照组提高52%,47%,生长到60 d时接菌组茎杆横截面积为对照组的124%,玉米活叶面积、叶宽、叶片垂高等都得到提高,并且随着生长期延长接菌和对照处理的差异增大。以曲率半径表示叶片弯曲程度,在生长到60 d时接菌组曲率半径比对照组增加46.5%,接种丛枝菌根真菌促使叶片更加坚挺。     

混凝土仿古坡屋盖施工的难点及解决方式

以太原某饭店改扩建工程为例,结合其仿古建筑屋盖为钢筋混凝土结构坡屋面形式的工程概况,针对施工中存在的多项施工难点,提出了具体的应对措施,并探讨了措施的效果,为今后的类似工程提供了参考借鉴。     

On estimating the interface normal and curvature in piecewise linear interface calculation-volume of fluid approach for three-dimensional arbitrary meshes

Volume of fluid (VOF) method with its Piecewise Linear Interface Calculation (PLIC) reconstruction algorithm is one of the most popular approaches in numerical simulation of interfacial flows with a wide range of applications in different areas. In an effort to evaluate the similarity of the PLIC-generated planes in comparison with the exact interface, a point-cloud, based on the polygon centers of PLIC planes is extracted, which later is used to form a triangular grid that represents the estimated interface. The main objective of this article is to evaluate the interface geometrical properties based on the extracted triangular grid of the interface. The methods presented in this article, characterized by a higher spatially convergence ratio, are compared with the commonly used methods. The proposed methods are tested for two 3-dimensional general test cases, where an evident improvement is seen in calculation accuracy and spatial convergence of the errors of interface normal vector and curvature.     

Effect of surface curvature and wettability on nucleation of methane hydrate

Natural gas hydrate nucleation is a complex physical and chemical process that is not well understood presently. In this article, an improved thermodynamic model is proposed to analyze the effects of surface curvature and wettability on methane hydrate nucleation for the first time. The results indicate that methane hydrate nucleation is more difficult on hydrophilic curvature surfaces under the same conditions, with a larger critical nucleation radius and required energy barrier than on hydrophobic surfaces. Furthermore, a convex surface is more favorable for forming methane hydrate under the same conditions than a concave surface. The model's results are critical in elucidating the microscopic mechanism of methane hydrate nucleation and providing a theoretical foundation for developing technologies for strengthening and inhibiting hydrate formation.     

Geometrical characterization of fluorescently labelled surfaces from noisy 3D microscopy data

Modern fluorescence microscopy enables fast 3D imaging of biological and inert systems alike. In many studies, it is important to detect the surface of objects and quantitatively characterize its local geometry, including its mean curvature. We present a fully automated algorithm to determine the location and curvatures of an object from 3D fluorescence images, such as those obtained using confocal or light‐sheet microscopy. The algorithm aims at reconstructing surface labelled objects with spherical topology and mild deformations from the spherical geometry with high accuracy, rather than reconstructing arbitrarily deformed objects with lower fidelity. Using both synthetic data with known geometrical characteristics and experimental data of spherical objects, we characterize the algorithm's accuracy over the range of conditions and parameters typically encountered in 3D fluorescence imaging. We show that the algorithm can detect the location of the surface and obtain a map of local mean curvatures with relative errors typically below 2% and 20%, respectively, even in the presence of substantial levels of noise. Finally, we apply this algorithm to analyse the shape and curvature map of fluorescently labelled oil droplets embedded within multicellular aggregates and deformed by cellular forces.     

小曲率拱型支架支护系统理论与试验分析

针对煤层顺槽梯形支架存在的问题,提出一种新型结构的小曲率拱型支架。采用曲梁模型进行了支架系统的受力分析,得到其最大承载能力;通过与直梁支架承载能力相比较,得到了小曲率拱型支架承载能力系数与曲梁跨度和半径的影响关系。同时进行了地面试压和井下支护工程实验。结果证明:小曲率拱型支架力学性能远优于梯形支架,支撑能力大,自身稳定性良好,有效解决了近距离和下分层煤层巷道不可锚且在强压下难支护的问题。     

The HLD Study of Surfactant Partitioning for Oilfield Corrosion Inhibitors

The partitioning of corrosion inhibitor (CI) products is a measure of their potential to protect oilfield pipelines. In this paper the hydrophilic–lipophilic deviation (HLD) model is first used to quantify their partitioning in terms of the characteristic curvature (C _c,act) of a series of anionic (alkoxylated phosphate esters) and cationic (alkoxylated amines, aromatic amines, imidazoline acetates and quaternary amines) actives. This parameter is expressed over a range of pHs within which pipeline corrosion occurs. The HLD model is next used to predict the partitioning of each active from water into toluene at increased salinities. Linear mixing rules are lastly used to predict the characteristic curvature of Product A (C _c,mix) as a function of the C _c,act of a subset of actives.     

PCO低渗透砂岩油藏裂缝特征综合描述

阿根廷PCO油田VOA1油藏为中孔、超低渗的砂泥岩薄互层砂岩储集层,油藏圈闭是单一大型鼻状构造。通过综合分析岩心资料、构造演化、地震曲率属性、蚂蚁追踪属性及油藏圈闭高部位纯油区内部部分井初产高含水的异常响应数据等资料,对构造裂缝的岩心直观特征、构造应变、空间分布范围和几何特征、动态开启机理等进行了综合描述。研究表明,综合地质、地震、生产等资料从多个角度描述裂缝特征及其相关性,可靠性高,可以大大降低单一方法描述裂缝的不确定性,为生产方案调整提供了有效保障。     

纯滚动单圆弧齿轮的齿面相对主曲率半径和齿面接触应力分析

根据微分几何原理对纯滚动单圆弧齿轮进行曲率MATLAB仿真,分析了纯滚动单圆弧齿轮的不同参数对相对主曲率半径的影响;基于弹性接触变形理论,计算纯滚动单圆弧齿轮传动的齿面接触应力,考查主要参数对纯滚动单圆弧齿轮齿面接触应力的影响,为后续的纯滚动圆弧齿轮的设计制造具有重要意义,为开发新型的齿轮接触强度计算提供借鉴。     

Effect of prestressed ultrasonic peen forming parameters on bending curvature and spherical deformation of plate

The elastic prestressed ultrasonic peen forming (UPF) was adopted in order to solve problems of insufficient bending deformation and large spherical deformation of plate during free UPF. The theoretical analysis of prestressed UPF and the influence of elastic prebending moment on deformation were analyzed. Spherical deformation coefficient was defined to quantificationally describe the spherical deformation. Experiments were conducted to compare the differences between free UPF and prestressed UPF processes and the effects of processing parameters on bending curvature and spherical deformation coefficient were studied. The results show that peening trajectory in chordwise direction is beneficial to enlarging spanwise bending deformation and decreasing spherical deformation coefficient. Large prebending curvature is helpful to increase spanwise bending deformation and decrease chordwise deformation, thereby obviously decreasing spherical deformation coefficient. Large spanwise deformation can be obtained under large firing pin velocity, small plate thickness and small offset distance. Large firing pin velocity plays a positive role in decreasing spherical deformation, while plate thickness and offset distance have little effect on it. Above all, prebending curvature and peening trajectory are the most important factors during prestressed UPF process. This study provides guidance for parameters optimization of prestressed UPF for wing plate with large thickness.