Advanced Materials Research Vols. 201-203

Abstract: The effect of electromagnetic field on the solidification structure of HMn084 brass (Cu-20%Zn-7.5%Mn-5.5%Al-1.5%Si-1%Fe-0.5%Pb in mass%) had been investigated in this paper. The results show that the as-cast structure of HMn084 brass is composed of matrix β-phase, small amount of α-phase and silicide (Mn, Fe)₅Si₃. Applying electromagnetic field during the solidification of HMn084 brass can refine grain and silicide phase, promote the uniform distribution of silicide phase. The morphology of silicide phase changes from coarse acicular and massive shape to fine acicular and massive shape. The above-mentioned effects become more obvious with the increasing in current intensity.

Abstract: Rock mass is the syntheses composed of kinds of structure and structured surfaces. The joint characters is influencing and controlling the rock mass strength, deformation characteristics and rock mass engineering instability failure in a great degree. Through using the RFPA2D software, which is a kind of material failure process analysis numerical methods based on finite element stress analysis and statistical damage theory, the uniaxial compression tests on numerical model are carried, the impact of the trace length of rock joints and the fault throws on rock mechanics parameters are studied. The results showed that with the gradual increase of trace length,compression strength decreased gradually and its rate of variation getting smaller and smaller, the deformation modulus decreased but the rate of variation larger and larger; with the fault throws increasing, the compression strength first increases and then decreases, when the fault throw is equal to the trace length, the deformation modulus is the largest. When the joint trace length is less than the fault throw, the rate of the deformation modulus is greater than that of trace length, but the deformation modulus was not of regular change.

Abstract: Angularity is an important parameter to evaluate the position precision. According the new generation of GPS, a new method of evaluating plane to plane angularity error based on coordinate rotation was proposed. In the process of evaluation, first the datum plane is associated by the minimum zone method; and then the datum plane is transformed into the ideal coordinate system plane. Based on the ideal datum, the plane is obtained by coordinate rotation; angularity error value is the maximum distance subtracts the minimum distance that measured points to the plane. The measurement for a V-groove in arbitrary position is performed on a three dimensional coordinates measuring machine; the result shows that angularity error can be evaluated effectually and accurately using this algorithm.

Abstract: Today's higher education has been international and universities confront increasingly fierce competition for survival. Therefore, it is significant to evaluate the teachers’ teaching management level for universities and to build the reasonable and fair teaching evaluation system. Based on widely investigating and studying lots of related literature, this article builds the index system which reflects the undergraduate teaching management level of higher education on the characteristic of undergraduate teaching management. This article focuses on the study of teaching quality evaluation of university teachers by the analytic hierarchy process (AHP) and fuzzy comprehensive evaluation. This model have rigorous logical reasoning and mathematical basis, they offer a new method for the teachers’ teaching management evaluation of universities.

Abstract: High performance XY-table is commonly used in packaging equipments which needs rational tolerance to ensure its high performance requirements and low manufacturing costs. The related studies mainly focus on high speed motion control algorithms and high precision structure design. The proper tolerance is essential in the development process of new products. In this paper, a new method for tolerance optimization based on Multi-body systems is presented. The volumetric error model for XY-table is established based on Multi-body systems. And then, by identifying the basic geometric error components, the relationships between the final output precision of the XY-table and the geometry error sources are established. The tolerance optimization model of XY-table using the above relationships is presented. In this model, objective function is the total manufacturing costs and the constraints are the above relationships. By solving the optimization model, the optimal tolerances are obtained. Finally, a tolerance design example of LED die bonder is given to illustrate the proposed method.

Abstract: As the human-centered product design has been emphasized as one of differentiated marketing factors, the products developed with the factors related to human characteristics are on an upward trend. Current development for the human-centered products is based on PPP(Product Performance Program) and UD(Universal Design) cases, but the products often results in being highly expensive so that a few of customers benefit from them. To achieve less expensive UD products, the initial stage of the product development needs to include value engineering (VE) that provides analysis tools for UD functions and their costs. This study presents UD development process integrated with VE.

Abstract: With technology of FRP reinforcement concrete beams is applied in domain of the civil engineering, it attracts more and more scholars to study it. The paper studied of the flexural fracture performance of FRP reinforced RC beams, bringing forward how to calculate the flexural failure of FRP reinforced concrete beam, namely: bearing capacity formula about broken FRP and crushed concrete on compression zone, through comparison between calculated values and tests values, it is discovered that the numerical analysis and test result is fitting approximately, it is validated that the formula can well analyze flexural of FRP reinforced RC beams.

Abstract: Evaluated with the yield of anise star oil, steam extraction method assisted by microwave is studied for the extraction of anise star oil from Illicium verum Hook. f. in contrast with the traditional steam distillation (SD) method in this paper. The new optimal steam extraction technology assisted by microwave of anise star oil is obtained as: extracting time 80 minutes, solid-liquid ratio(g/mL) 1:7, size of material 80~100 mesh and extracting temperature 80°C. Average yield of anise star oil is up to 11.6% (g/g) under the above technology. Size of material is the most important influencing factor in the extraction process. The optimal traditional steam distillation technology is: extracting time 120 minutes, solid-liquid ratio(g/mL) 1:6, size of material 80~100 mesh and extracting temperature 100°C , the average yield of anise star oil is only 9.81% (g/g). The steam extraction technology assisted by microwave has advantages in both the technological conditions and the yield of anise star oil than the traditional steam distillation technology.

Abstract: Delays are one of the biggest problems in construction projects in developing countries, as cause negative effects on the projects. Delays can be minimized only when their causes are identified. This paper aims to identify effective methods of minimizing delay in construction projects. The literature related the field of causes and effects of delay and methods for minimizing construction delay has been reviewed over the last decade. This paper highlighted methodology to reduce construction delays from consultant and contractor viewpoints. The perspective of contractors and consultants has been analysed to rank the methods of minimizing construction delays based on their Relative Importance Index (RII). The most effective methods of minimizing delay in construction projects were: adequate funding throughout the project, competent project manager, awarding bids to the right designer/contractor, complete and proper design at the right time, availability of resources, clear objective and scope, and the use of experienced subcontractors and suppliers. The result can be used as a guideline to successfully handling construction projects in Iran as well as other developing countries.