Recent Patents on Mechanical Engineering - Volume 5, Issue 2, 2012

Over the past three decades, significant patents have been devoted to the development and implementation of thermoacoustic devices in several applications. Thermoacoustic is the science concerned with the interaction of thermodynamics and acoustics. These interactions exist due to the fact that the sound wave consists of pressure waves and these pressure waves affect the thermodynamic characteristics of the gas. Eventually, with a relatively simple structure and environmentally benign gas, the sound can be transformed into heat and vice versa. This phenomenon can be utilized in many engineering applications such as power generation and refrigeration. Thermoacoustic devices can be classified into two main categories; thermoacoustic engine and thermoacoustic refrigerator. This paper presents an overview of the thermoacoustic principles and a summary of the recent patents on thermoacoustic devices along with the current research trends in this field.

The Large-Eddy Simulation (LES) technique is an important modeling method in the numerical simulation of turbulence. Some recent patents on the LES technique are reviewed in this contribution. They are classified into three types: the theoretical progress, the mesh generation and optimization, and the practical applications. Discussion is then made on the current and future developments of this technique.

A new constant scallop-height smooth tool-path planning algorithm is presented in this paper. The algorithm can generate smooth tool path by controlling the curvature of the tool path so as to avoid the tool path’s inflexion which is often generated in traditional constant scallop height tool path planning affecting the machining surface quality. Taking a parametric surface for example, the algorithm is programmed using Matlab software and compared with the traditional one, the result shows that this algorithm can acquire the minimum curvature radius of tool-path line and improve machining quality. Especially in high speed milling, the idea of algorithm has obvious merits in practice. The paper ends with some recent patents and further developments in the fields. A method for calculating depth of cut without any milling selfexcited vibration, a system produces orthodontic aligners by CNC machining and etc.

A solution to the state estimation problem of systems with unmeasurable non-zero mean inputs/disturbances, which do not satisfy the disturbance decoupling conditions, is given using the Kalman filtering and Bayesian estimation theory. The proposed estimation algorithm, named Supervisory Kalman Filter (SKF), consists of a Kalman filter with an extra update step which is inspired by the particle filtering technique. The extra step, called supervisory layer, numerically solves the measurement equations for the portion of the state vector that cannot be estimated by the Kalman filter. First, it produces N randomly generated state vectors, the particles, which are distributed based on the Kalman filter's last updated estimate. Then, the estimated measurement vector associated with each particle is compared to the actual measurement vector to identify the particle's probability to be a solution. Finally, a so-called resampling stage is implemented to refine the particles with higher likelihoods. The effectiveness of the SKF is demonstrated by comparing its estimation performance with that of the standard Kalman Filter and the particle filter for a vehicle state estimation problem. The estimation results confirm that the SKF precisely estimates those states of the vehicle that cannot be estimated by either the Kalman filter or the particle filter, regardless of the unknown disturbances from the road. The filtering methodology offered in the article has a potential to improve performance of the systems presented in the patents WO2011115960, WO2010024751, US8073528, and US20110299730.

Wear properties of two different crushers used for grinding raw materials of cement industry are compared using pin on disk wear test. The wear test was carried out with different loads on a pin. Abrasive wear behavior of two crushers made of Hadfield steel and high chromium cast iron was evaluated by comparing weight loss, wear resistance, microhardness and friction coefficient. The results showed that abrasive wear of high chromium cast iron was lower than Hadfield steel because of the larger amount of carbides and higher work hardening in the steel at the higher applied loads. Increase in surface hardness of Hadfield steel was more noticeable compare to high chromium cast iron due to the work hardening and formation of the twining sites during the wear test. Owing to the presence of M7C3 carbides in high chromium cast iron matrix, impact crushers exhibited higher friction coefficient. In addition, a wear loss equation was derived based on a real crushing condition. However, a new approach in optimization of the wear parameters was developed and wear behavior of the materials was predicted based on the maximum number of the effective factors. The optimization of the parameters by genetic algorithm showed that optimum wear loss for hammer and impact crushers under real condition is 5.2958 mg and 3.8449 mg, respectively. Results of the numerical simulation show that the genetic algorithm optimization is effective and very useful in designing the hammer and impact crushers. In addition, some recent patents on abrasive wear behavior of the high chromium cast iron and Hadfield steel are discussed in details.

Sheet metal forming plays an important role in industry nowadays. Drawing is a popular processing for the sheet mental forming. The drawing process is difficult to control because of many factors affecting the whole forming process. In order to solve the problems encountered in practice, some new methods have been invented. This paper reviews various patents of suppressing defect through adopting new structure and new device in recent years, especially the patents on the drawing die structure with floating punch by hydraulic pressure. In addition, this article introduces a method to solve the problem by applying a new structure. These new structures, which are appropriate for the characteristics of the product, adjacent to each other and the forming depth is deep. The article also introduces a method to solve this problem. The new structure has one or more floating punches with the hydraulic pressure according to the characteristics of the product. During the process of sheet mental forming, The drawing force is put on the floating punch, which makes the sheet mental flow into the cavity of the die. Meanwhile the force provided by hydraulic varies according to the curve because that different status of forming needs different forces. The floating punch has a guide post to assure the precision of up-down moving. Comparing with traditional die structure, the new structure can increase the forming depth of adjacent characteristics and reduce the number of drawing. Therefore, the method is useful and the cost can be reduced.

Composite electroforming is a special processing technology. At the beginning of the paper, some recent patents related to it are discussed simply. The electroforming technology is used in the device, for making a micro metal nickel mold and disclosed a Cu-W-Ni copper matrix composite. It can be used for forming coating or free standing deposit of nanocrystalline metal, metal alloys or metal matrix composite. What's more, in this paper, the study of fundamental research on rare earths binary nanocomposite electroforming technology was carried out, using rare earth's nanoparticles and ceramic nanoparticles as suspended particles in electroforming bath. The effects of process parameters on the nanoparticles content in deposits were investigated. By analyzing and testing surface morphology, microstructure and properties of the electroforming deposits, the optimum process of preparing the electroforming deposit was obtained. Furthermore, the mechanism model of two kinds of nanoparticles or more codeposited with metal was put forward. Moreover, the effect of two kinds of nanoparticles on the properties of electroforming deposits was analyzed. The conclusions are presented as follows: the nanocomposite electroforming layer with outstanding properties could be obtained under the conditions of the lower cathode current density and appropriate nanoparticles ratio. Due to the existence of CeO2 and ZrO2 nanoparticles, crystal growth patterns of Ni in nanocomposite electroforming deposit change gradually to the growth of matrix metal Ni along (2 0 0) the crystal face; because of CeO2 and ZrO2 nanoparticles codeposition, the rare earths binary nanocomposite electroforming deposit has excellent properties, mainly attributed to dispersion strengthening effect and refining crystal strengthening effect of CeO2 and ZrO2 nanoparticles.

The objective of this article is to examine the local thermal non-equilibrium model (LTNE) in the periodic magneto- hydrodynamic (MHD) natural convection flow in a channel filled with a non-Darcian media. The periodic disturbance in the free convection flow results from a periodic sinusoidal thermal disturbance imposed on the channel walls. The Darcy-Brinkman-Forchheimer model is implemented to simulate the flow inside the porous media. Six dimensionless parameters are found to have significant effect on the local thermal equilibrium. The effects of these parameters on the adaption of thermal non equilibrium model are studied in details. The volumetric Nusselt number is found to have the most significant effect on the adoption of this model. This paper is the first attempt in introducing Thermal nonequilibrium model in the periodic MHD free convection and this model is essential in many patents based on LTNE MHD generation and devices.

Recently significant patents have been devoted to plane wall jet systems. In this paper, the self-similar wall jet over an impermeable, resting plane surface known as the Glauert-jet is analyzed. The DTM and Pade Approximant were used to find analytical solution. In order to verify the accuracy of the proposed method, the resultant data were then compared with previously obtained results using the homotopy analysis method (HAM), method of weighted residuals method (MWR), variational iteration method (VIM) and exact solution. It can be concluded that the DTM-Pade can achieve more reliable results in calculating the solution of such problems.

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