Numerical study of enhancing vehicle radiator performance using different porous fin configurations and materials

A vehicle radiator is used for cooling down the hot working fluid with airflow passing over its flow passages and fins. The proper design of the radiator is very important due to space and weight limitations in automobiles. In this study, a numerical investigation has been conducted on the improvements, which can be obtained by implementing different porous fins in the radiator channels. The effects of different porous fin configurations with the same porous media volume on the heat transfer rate and pressure drop were investigated. The coefficient of performance values were presented for evaluating the overall performance. The investigated geometries included horizontal, vertical, corrugated, and wavy‐corrugated configurations. The results showed that the corrugated pattern had the best thermal performance among these geometries while the horizontal configuration presented the lowest pressure loss, even though the best overall performance belonged to wavy‐corrugated configuration. After selecting this configuration, the influence of different porous materials on the radiator performance was studied. Finally, the radiator with the optimum porous media configuration and material was compared to a conventional radiator. It was found that implementing this porous media in the radiator channels improves its overall thermal performance factor up to 237%.     

Analyse du champ électromagnétique dû à une décharge de foudre dans les domaines temporel et fréquentiel

The paper presents an analysis in the time and in the frequency domain of the electromagnetic field originated by negative lightning return strokes, calculated at ground level. The analysis is performed on the basis of the « Transmission Line » model modified by the authors, which gives results in good agreement with experimental data. The influence of several parameters which deeply affect the time waveshape and the frequency spectra of the electromagnetic field has been investigated. These parameters are : the rise time and the peak value of the lightning current pulse, its velocity of propagation and the rate of decreasing of the intensity of the current pulse propagating along the channel. The influence of other parameters such as the lightning channel height and the distance of the observation point is also analyzed. It is shown that the height of the channel does not affect practically the electromagnetic field. Two simplified expressions of the electromagnetic field used for the calculation of overvoltages induced on transmission lines are discussed in order to assess their validity limits.     

Dynamic analysis of a 6 DOF CKCM robot end-effector for dual-arm telerobot systems

In this paper, we present the dynamical analysis of a six-degree-of-freedom robot end-effector built to study telerobotic service and maintenance of NASA hardwares in space. The design of the end-effector is based on the concept of closed-kinematic chain mechanism capable of performing precise motion in a small workspace. After presenting a closed-form solution for the inverse kinematic problem, we employ the Lagrangian approach to derive a set of equations of motion for the end-effector where the generalized coordinates are selected to be the Cartesian coordinates. Computer simulation study shows that the centrifugal and Coriolis terms can be neglected fow slow motion. Effects of system parameters on the end-effector dynamics are also studied using computer simulation.     

Use of multi‐criteria decision‐making for selecting spillway type and optimizing dimensions by applying the harmony search algorithm: Qeshlagh Dam Case Study

Economic considerations are significantly important in designing a dam and its related hydraulic structures. Considering the methods used for economic design of hydraulic structures such as a spillway, they are also dependent on the construction costs of the spillway. In addition to the spillway type and capacity being associated with the magnitude of floods. Selecting different options of a spillway, considering all their aspects, has always been one of the biggest issues in decision‐making. The present study determined the best spillway type (free‐flow, stepped, semicircular and cylindrical) for Qeshlagh Dam, Iran, by considering different aspects (costs, time and performance) and using the TOPSIS method. The obtained dimensions of the spillway from multi‐criteria decision‐making were then optimized using meta‐heuristic Harmony Search Algorithm (HSA). The results identified a free‐flow spillway was the best option in terms of cost and time, whereas a cylindrical spillway is the best choice in terms of performance. The optimal free‐flow spillway length is 31.8 m, and height is 3.45 m, being capable of passing a flood discharge of 452 m³/s. This discharge was calculated by a reservoir routing method. Moreover, the obtained solution led to reducing the spillway construction costs, one of the most important issues in civil engineering projects.     

Integrated Structural–Architectural Design for Interactive Planning

Traditionally, building floor plans are designed by architects with their usability, functionality and architectural aesthetics in mind; however, the structural properties of the distribution of load‐bearing walls and columns are usually not taken into account at this stage. In this paper, we propose a novel approach for the design of architectural floor plans by integrating structural layout analysis directly into the planning process. In order to achieve this, we introduce a planning tool which interactively enforces checks for structural stability of the current design, and which on demand proposes how to stabilize it if necessary. Technically, our solution contains an interactive architectural modelling framework as well as a constrained optimization module where both are based on respective architectural rules. Using our tool, an architect can predict already in a very early planning stage whose designs are structurally sound such that later changes due to stability reasons can be prevented. We compare manually computed solutions with optimal results of our proposed automated design process in order to show how much our proposed system can help architects to improve the process of laying out structural models optimally.     

Pre-bent shape design of full free-form curved beams using isogeometric method and semi-analytical sensitivity analysis

In this paper, isogeometric analysis (IGA) is employed to solve the problem of a curved beam with free-form geometry, arbitrary loading, and variable flexural/axial rigidity. The main objective of the study is to develop a unified approach for full free-from curved beam problems that can be integrated with a newly developed semi-analytical sensitivity analysis to solve pre-bent shape design problems. The required set of B-spline control points are calculated using an interpolation technique based on chord-length parameterization. The one-to-one correspondence is considered for parameters of the geometry, loading, and rigidity which is proven to have extreme importance. An IGA curved beam element is suggested based on the Euler-Bernoulli beam theory for the general curvilinear coordinate. The validity and effectiveness of the proposed formulation is confirmed by application to a variety of examples. Moreover, three shape optimization examples are taken into consideration. In the first two examples, the pre-bent shapes of spiral and Tschinhausen curved beams with free-form geometry under distributed loading are obtained. In the third example, the pre-bending problem of wind turbine blades is addressed as an industrial example.     

An MLP-based representation of neural tensor networks for the RDF data models

In this paper, a new representation of neural tensor networks is presented. Recently, state-of-the-art neural tensor networks have been introduced to complete RDF knowledge bases. However, mathematical model representation of these networks is still a challenging problem, due to tensor parameters. To solve this problem, it is proposed that these networks can be represented as two-layer perceptron network. To complete the network topology, the traditional gradient based learning rule is then developed. It should be mentioned that for tensor networks there have been developed some learning rules which are complex in nature due to the complexity of the objective function used. Indeed, this paper is aimed to show that the tensor network can be viewed and represented by the two-layer feedforward neural network in its traditional form. The simulation results presented in the paper easily verify this claim.

     

A group signature based buyer coalition scheme with trustable third party

Despite the large number of existing buyer coalition schemes and increasing need for trusting relationship in buyer coalitions, no current buyer coalition scheme explicitly addresses trust issues within these schemes in a formalised manner. Without establishing a trusting relationships among various roles, many buyers may not be willing to join the coalitions. This study proposes a solution, in the form of an algorithmic design, as a response to the above need. Specific features of the proposed solution are: (i) the use of ‘group signature’ in order to guarantees anonymity within a group that results in trustfulness of the relationships and (ii) introducing a new role called ‘authority’ to maintain and implement anonymity. In addition, the proposed scheme is capable of maintaining ‘correctness’ and ‘accountability’ by both identifying misbehaved buyers as well as implementing various punishment methods.Knowledge domain of the study is the common space between three overlapping fields including Electronic Commerce, Communication Technologies and Information Systems.