Applied Mechanics and Materials Vols. 66-68

Abstract: The model of heat transfer tube was established to obtain the distribution of velocity field, temperature field and pressure field with the aid of the computational fluid dynamics (CFD). The effect of the twisted-tape on the distribution of all fields in the tube was discussed. Seven pipes were constructed with different torsion to examine the torsion ζ and Re effect on the heat transfer and flow resistance. Nusselt number Nu and the ratio of pressure difference △P /△ P₀ in the tube with and without twisted-tape inserted was used to measure the heat transfer and flow resistance. The results show that the twisted-tape and large Re can enhance heat-transfer efficiency to some extent in same conditions; however it also leads to the loss of flow resistance. Structure optimization by changing the parameters and Re is what we should consider for further research.

Abstract: The usual research method, on rheology of fresh self-compacting concrete, is that the regression models between rheological parameters and workability were established, and then the rheological test was operated to control fresh SCC. But, there is no rheometer used widely on site, already. So this paper developed an adaptive neuro-fuzzy inference approach of the back analysis of workability on fresh SCC rheology, and workability tests can be taken to inverse the rheological parameters, by adaptive neuro-fuzzy inference system. In order to check the correctness of this approach, a rheological problem of fresh SCC was solved by it, and the inversion results were in good agreement with the rheological parameters, and the predication accuracy of ANFIS models was quite sufficient to meet the engineering requirement.

Abstract: To analyze and calculate the element characteristics matrices of space Timoshenko-beam, research work were carried out on the basis of energy variational principle. Displacement function for the space Timoshenko-beam were put forward, the expressions for element mass matrix, stiffness matrix and load array were deduced by energy functional extremum, and the explicit forms of element mass and stiffness matrices were integrated finally. Results show that the element mass and stiffness matrices computed by this method are consistent with those in related references. It has a good theoretical and practical value in the calculation for characteristics matrices of other elements.

Abstract: There is a constant need for the reduction of operational and maintenance costs of Wind Energy Conversion System (WECS). The most efficient way of reducing these costs would be to continuously monitor the condition of these systems, which allows for early detection of the degeneration of the generator health, facilitating a proactive response, minimizing downtime, and maximizing productivity. Wind generators are also inaccessible since they are situated on extremely high towers, which are usually 70m more in height. There are also plans to increase the number of offshore sites increasing the need for a remote means of WECS monitoring that overcomes some of the difficulties of accessibility problems. Therefore it is important of condition monitoring and fault diagnosis in WECS. A monitoring scheme of transfer its monitor status with AJAX technology was put forwords in this paper. A remote condition monitoring platform (RCMP) was designed and constructed in this project. And its result brings us an effective solution to deal with the WECS condition monitoring.

Abstract: Long annular rack pumping unit is a new styles of pumping unit invented by Gu Xinyi academician. It has some advantages including energy conservation and high reliability. In order to understand the dynamics of the new pumping units, the virtual prototyping model of this pumping unit is build. The kinematics and dynamics characteristics of this unit are researched and simulated. The results can be a guidance for the design and practical application.

Abstract: To estimate the states and uncertainty of the under-actuated ship, the paper proposed a modified UKF algorithm—Singular Value Decomposition UKF based on acceleration, which simplifies the system reference equation, reduces the calculation complexity and increases the accuracy of the algorithm. The accuracy and calculation complexity of the algorithm are analyzed in detail. Numeric simulation demonstrates the effectiveness of the algorithm.

Abstract: The study of Low-Cycle fatigue showed that strain is more important parameter than stress for describing fatigue property of materials .Exactly obtaining regional strain of the structure by analysis is key in fatigue design of complex structure .Therefore, the analysis and solution by finite element is very necessary. The maximum elastic and plastic strain at the nozzle junction of a pressure vessel under several loadings are calculated by using ANSYS software .Then crack forming life is calculated by using the N.E.Dowling formula .

Abstract: Tailing sand is one of the residue minerals obtained after tin extraction. It contains silica in between 94% and 99.5% and available in abundance at the Kinta Valley, Perak State, Malaysia. Permeability is one of the important molding sand properties and considered much in the sand casting mold preparation. This molding sand property plays a vital role in the sand casting process and helps to remove the gases during the casting processing. In this research work, samples of tailing sands were gathered from four identified ex tin mines located at the Perak State, Malaysia. They were investigated by the standard sand testing procedures prescribed by the American Foundrymen Society (AFS). Sand specimens of size Ø50 mm×50 mm in height from various sand–water ratios bonded with 4% and 8% clay were compacted on applying three ramming blows of 6666 g each by using a Ridsdale-Dietert metric standard rammer. The specimens were tested for permeability number with the aid of a Ridsdale-Dietert permeability meter. Before the tests were conducted, the moisture content was measured by using a moisture analyzer. The results were compared with the properties of the molding sand samples collected from RCS Manufacturing Sdn. Bhd., the company supplying sand to the Proton Casting unit car manufacturing company. The molding sand sample sample bonded with 8% clay was found to have maximum permeability with an optimum allowable moisture content range of 3.5-6.0% and for the sand mixture bonded with 4% clay at 3.0-3.5% moisture.

Abstract: The transmutation target of nuclear waste material has been fabrication by a powder metallurgy method by using Alumina as the matrix and CNTs as reinforcement. The effect of different nanotube contents on the fracture toughness and the bending strength was investigation. The results showed the fracture toughness and the bending strength of composites increased with increasing CNTs mass fraction when the content of CNTs was less than 1.5%. However, when the contents of CNTs greater than 1.5%, the fracture toughness and the bending strength of composites decreased as the content of CNTs increased. Possible mechanisms are discussed in detail in the paper.

Abstract: The inflatable cover was used in the low-temperature blackbody radiation source; the function of the external gas separation had great influences on blackbody radiation source performances. This paper presents a new way for performing numerical simulation for the three-dimensional inner flow field analysis of new inflatable cover and blackbody radiation source cavity by using the FLUENT software of CFD. By comparison, the simulation results and the acetone tracer particle experiments revealed the reason of the outside air into the cavity caused frost and dew, so we proposed a number of methods to reduce air convection inside and outside of the cavity for the using inflatable cover, and it gave theoretical basis guidance for the next optimal design of the new inflatable cover.