科学方法论在材料力学课程教学中的应用

经过对几届学生的教学实践总结出:将科学方法论中的一些方法应用到材料力学课程教学中,这样不仅能使学生掌握该课程的内容,而且还能学到科学方法。这对学生学习新知识、新技能和和培养他们独立思考解决问题及创新能力都很有益处。     

An examination of the mechanical interaction of drilling slurries at the soil-concrete contact

Evidence gained from previous field tests conducted on drilled shaft foundation shows that using drilling slurries to stabilize a borehole during the construction may influence the interfacial shear strength. This paper deals with an exhaustive study of the effects of drilling slurries at the contact between soil and concrete. This study involved adapting a simple shear apparatus and performing approximately 100 experimental tests on the interaction between two types of soils; clay and sandy clay and five specimens of concrete with different surface shapes. It also involved using bentonite and polymer slurries as an interface layer between soil and concrete. Results showed that an interface layer of bentonite slurry between clay and concrete decreases the interfacial shear strength by 23% and as an interface layer between sandy clay and concrete, bentonite increases interfacial shear strength by 10%. Using polymer slurry as an interface layer between clay and concrete decreases the interfacial shear strength by 17% while using it as an interface layer between sandy clay and concrete increases the interfacial shear strength by 10%. Fur- thermore, the data show that using bentonite and polymer slurry as an interface layer between clay and concrete decreases the sliding ratio by 50% to 60%, while increasing the sliding ratio by 44% to 56% when these are used as an interface layer between sandy clay and concrete.     

Scaling-up Sustainable Land Management Practices through the Concept of the Rural Resource Centre: Reconciling Farmers' Interests with Research Agendas

Abstract

Purpose: Formal agricultural research has generated vast amount of knowledge and fundamental insights on land management, but their low adoption has been attributed to the use of public extension approach. This research aims to address whether and how full participation of farmers through the concept of Rural Resource Centre (RRC) provides new insights for the development of alternative and farmers-based extension methods.

Design/Methodology/Approach: Using the Concept of RRC, this research assesses the role of farmers in on-farm demonstrations and scaling-up of land management practices, and investigates effective ways to enhance beneficial interactions between researchers, extension workers and farmers in view of improving adoption.

Findings: The findings suggest that farmers can effectively participate in demonstrations and scaling-up of agricultural practices. This participation is enhanced by judicious incentives such as higher crop yields that motivate farmers and influence adoption. The current success of the approach stems from the fact that farmers, extension workers and researchers jointly implement the activities and their different aims were achieved simultaneously: scientific results for researchers, better agricultural practices for extension workers, and economic success and free choice for farmers.

Practical implications: This research concludes that farmers have the capacities to play an innermost role in demonstrations and scaling-up of agricultural practices. However, there is a need to build and strengthen their capacities to facilitate their participation and contribution.

Originality/Value: The article demonstrates the value of the preponderant role of farmers in on-farm demonstrations and scaling-up practices by exhibiting the beneficial interactions between researchers, extension workers and farmers.     

Farmers' Adoption of Soil Conservation Technologies: A Case Study from Osun State,Nigeria

Abstract

The main objective of this study was to determine the attitude of farmers towards erosion and the adoption of appropriate soil conservation technologies (SCTs). For the survey, farmers were selected from the communities Esa Oke, Elwure and Owode-Ede and Akoda in Osun State in Nigeria. In the first three communities farmers did receive training on soil conservation, in the fourth not. About 60 farmers were interviewed to obtain information on personal and socio-economic characteristics, awareness of environmental problems, attitude towards erosion control and experiences with SCTs. Statistical data analyses (analyses of frequencies, correlation, t-test, χ²-test) were made to examine possible relationships among parameters and the influence of factors on adoption.

Most respondents were advanced in years, responsible for large households and characterized by low levels of income and literacy. Soil erosion was seen as a problem confronting agricultural production only to a small extent. The adoption rate of SCTs was low, as only mulching, cover cropping, contour tillage and cut-off drainage were practised and often rejected. Low labour-demand, the availability of common equipment, low costs of application, ease of practice and compatibility with the existing farming system influenced adoption.

The observed positive correlation between level of education, knowledge of appropriate technologies, farming experience and the number of SCTs adopted emphasizes the importance for farmers of education and training. Strengthening agricultural extension agencies for capacity building is an important tool for improving soil conservation in Nigeria.

The paper clarifies with specific examples the causes of the low rates of adoption of available technologies, with a reduced impact of research and of efforts to achieve food security and sustainable production at village level.     

博斯腾湖湖滨带绿洲土壤盐分特征分析

以博斯腾湖湖滨绿洲为研究区,通过野外土壤调查和采样,运用描述性统计学方法与灰色关联度分析博斯腾湖湖滨绿洲土壤盐分特征．研究结果表明：0～10cm、10—30cm与30—50cm土壤表层总盐分的变异系数分别为65．35％、37．00％和39．71％呈现中等变异性;对土壤含盐量影响最大的离子是Na＋＋K＋、CL^-、SO4^2-;在四种土地利用类型中,草地的盐分含量均值最高,而裸地、耕地和林地的盐分含量均值较低,分别为2．74g／kg、2．70g/kg,2．38g/kg和2．63g／kg．     

寒地黑土民族民间文化的法律保护

寒地黑土文化是绥化地区土生土长的地域特征极其明显的北方文化,绥化的寒地黑土特色文化具有深厚的民族、民间文化底蕴。随着当前全球经济社会的快速发展,国内和外来强势文化对本来一直处于弱势文化地位的民族民间文化产生了前所未有的冲击,其生存和发展面临着重大危机。寒地黑土文化也面临着失传、濒危的重大危机。因此加强对民族民间文化的法律保护的重要性和紧迫性日益突出。     

从《土力学》的学科特点谈高职高专土力学的教学方法

土力学没有统一的力学体系,是一门实践性很强的学科,本质上兼顾了技术科学和工程科学的双重特性。高职高专院校土木类专业要按照高职高专院校人才培养规格要求,根据工程背景提出工程问题,根据工程问题讲授解决方法和理论,根据工程案例讲解理论应用的原则组织土力学教学,并在具体教学中强调基本概念,重视土的工程性质;强调试验,重视实践技能培养;强调案例教学,重视工程能力培养。     

哈萨克毡房及其几何体结构

哈萨克毡房是根据长期游牧生活需要而制造的传统住房,其历史悠久。首先介绍了哈萨克毡房的传统结构,然后从数学和力学的角度研究了哈萨克毡房的整体科学结构。     

温度对C15、C30、C40、C60、C80力学性能的影响

采用C15、C30、C40、C60、C80混凝土配合X衍射试验、差热试验和热膨胀试验,对不同标号的混凝土在不同组分及中高温下所发生的一系列物理化学变化进行了研究与分析,从而探讨温度对混凝土影响的一些因素,以及在相同温度条件下,不同标号的混凝土所表现的一些性质的差异,从而为工程中使用混凝土提供一些参考。通过多项试验分析,混凝土在受到高温时,必然会发生一些物理化学变化,从而使其强度下降并发生性能的衰减。同时,通过数据的比较发现,高标号的混凝土在高温下发生物理化学变化时所需的温度比低标号的混凝土要高,因此发生破坏的最终时间要相对滞后。     

冀西北黄土丘陵区小流域综合治理和土地利用模式研究

水土流失是冀西北黄土丘陵土地退化和农业经济落后的主要原因之一，而不合理的土地利用结构，粗放耕作，广种薄收等因素又使该区土壤侵蚀日益严重。本文应用遥感方法通过对典型市区涿鹿县石瓮小流域土壤侵蚀的定量分析和土地利用现状的调整及其主要问题的剖析，将水土保持规划和土地利用结构优化有机地结合了起来，充分体现了水土保持的综合治理原则和土地资源合理原则，以及生态效益和经济效益科学统一的原则。初步提出了一套河滩水浇地基本农田带——梁峁缓坡地集约经营梯田果林带——梁峁陡坡地旱作果粮间作带——梁峁顶部缓坡地旱粮作物——土—石过渡区、石质山灌木林和用材林带的以农果为主、多种经营立体布局的小流域综合治理和土地利用模式，在冀西北黄土丘陵区县有推广意义。