阿赛管道稳定运行的进站温度预测与评价

长距离热油管道输送介质的组成一般比较复杂,为维持其经济输送温度,常出现蜡等重有机物固相沉积问题。当固相沉积超过一定程度时,不仅显著增加管道系统的动力消耗,而且严重威胁其运行安全。因此,合理预测热油管道稳定运行的进站温度对保障其安全经济运行尤为重要。依据阿尔善-赛汉塔拉输油管道2008-2010年的历史运行参数,结合苏霍夫温降理论,反算全线7个管段稳定运行期间的总传热系数K,提出不同管段的月推荐K值,以此预测各管段2011年上半年的进站温度,探讨偏差产生的主要原因与预测结果的可靠性。研究结果表明:由热油管道历史运行参数反算得出的推荐K值,可以较好地预测该管道今后的温降趋势,误差在-4～4℃内的可信度高于90%,但进站温度预测值可能因固相沉积而略低于实际值。     

振冲碎石桩在粉砂地基中的应用

以设计为依据,结合工程实际情况,通过碎石桩在粉砂地基中的试桩实验,提出如何控制碎石桩施工时的水压、电流、留振时间等施工要点,以便更好的提高碎石桩的使用效果。     

一个较为精确的半离散的Hilbert型不等式

应用权系数的方法及Hadamard不等式,建立了一个具有最佳常数因子的、较为精确的半离散的Hilbert型不等式,并考虑了它的等价式.     

Applicability of stand structural characteristics to stemflow modeling

A stemflow (SF) estimation model, based on the correlation between coefficients (a andb) of the regression equation (SF=aP _g −b, whereP _g is gross rainfall) obtained from sample tree and their diameter at breast height (DBH), is presented. Estimation by the model forSF from two deciduous broad-leaved forests shows favorable agreement with the measurement. Once the equations for regression coefficients are determined, the model has the potential to easily estimateSF from an entire stand through sampling of some representative trees. However, the model is site-specific. In order to mitigate the weakness of this model, the combination of previous results provided generalized equations for the coefficients. The generalized equation adequately estimatedSF of some forests while its estimation was biased for other forests, which indicates thatSF variation between forests is closely related to structural differences. Actually, theSF frequency distribution of two forest stands was significantly different. So, influence of structural factors onSF was also studied using funneling ratio (FR) that integrates the efficiency of trunk and canopy characteristics toSF. Comparison ofFR showed thatSF was significantly correlated to crown-projection area (CPA) and basal area at breast height (BA). Parameters (β ₁ andβ ₂) within the model were significantly correlated to respective stand density and leaf area index (LAI). Part of this study was supported by Aichi Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence, Japan Science and Technology Corporation.     

Experimental verification of bandsaw roll-tensioning theory

The validity of a bandsaw roll-tensioning theory developed by the author is verified based on a model experiment. It is shown that the actual roll-tensioning process can be clearly explained by this theory. Roll-stretching force transmission coefficients are introduced in this theory. These coefficients, which indicate the magnitude of the compression force parallel to the bandsaw surface at the roll-stretching position, are affected by the thickness of the bandsaw blade, the radius of the bandsaw blade vent at the measurement of tension, and the straightness of the bandsaw blade at the measurement of crown back, among others. For the practical use of this theory, therefore, it is necessary to determine the proper magnitude of these coefficients based on tensioning experiments.     

Analysis of moisture diffusivity of larch timber during convective drying condition by using Crank＇s method and Dincer＇s method

Two analytical procedures （Crank＇s method and Dincer＇s method） for porous solid materials were reevaluated and used to determine moisture diffusion coefficients and moisture transfer coefficients for larch lumber subjected to drying. A diffusion-like equation was used to describe drying process data. The lumber was idealized in the modeling as infinite plates. The moisture transport process inside the board was assumed to be one-dimensional. The macroscopic drying kinetics curves of larch timber at particular conditions were determined experimentally. Based on these data, calculation for both the moisture diffusion coefficients and moisture transfer coefficients by the Dincer＇s analytical procedure were made. The dynamic moisture diffusion coefficients by the traditional Crank＇s method were calculated. In general, diffusion coefficients calculated by the Dincer＇s method were all higher than those by Crank＇s method. These results could be due to the differences between two analytical methods and also different characteristics between solid moisture diffusion process and heat transfer process. Therefore the analysis and solution procedures of moisture diffusion differential equations need to be adapted in the future. With drying temperature＇s increasing moisture diffusion coefficient （D） and moisture transfer coefficient （k） increases accordingly. Also the relationships between diffusion coefficients and temperature as well as material moisture contents were analyzed by using Arrhenius equation and bound water transport theory.     

Modelling of the behaviour of free water in sapwood during drying

A stochastic three-dimensional model for the behaviour of free water in wood, which was described in Part I, is used for the simulation and analysis of some further features of wood drying. The kiln brown stain mechanism is studied and the connection to the condition of the wood surface is pointed out. Several drying rate questions and related aspects are analysed and compared with experimental results. Finally the risk of surface checking in an early stage of sapwood drying is shown theoretically.     

杨树栽培区划的研究

运用277个县23个杨树品种的2 980块标准地的调查资料,采用聚类分析方法,把全国杨树栽培范围划分成13个栽培区,并作了生产力评价。     

林带的防风效能及数字模拟

林带的防风效能既与林带本身的结构因子如:林带结构类型、疏透度或透风系数、截面形状、高度、宽度等有关,也受天气和地面状况等因子的影响。因此,通过野外观测研究,弄清单因子对不同透风系数、幅宽对林带的防风效能的影响很困难,采用风洞模型模拟试验,可以取得满意的结果。本试验于1989年6月在日本北海道大学环境研究科风洞试验室进行。风洞风速与实     

杉木无性系选育与无性系造林

本文围绕如何实现我国杉木造林良种化的问题,阐述了杉木天性系造林的重要性。介绍了我国杉木无性系选育与造林的研究现状、取得的成果及有关技术要点,指出在我国推广杉木无性系造林的条件已经基本具备,以及在实践中尚须加以解决的问题。对促进我国推广杉木无性系造林具有一定价值。