Method for the pre-dimensioning of beveloid gears

Conical involute gears – also referred to as beveloid gears – are based on cylindrical involute gears, as both gear geometries are based on a basic rack. They differ from cylindrical gears in that the beveloid gears’ addendum modification along the face width is not constant, but linearly variable. This allows beveloid gears to transfer mechanical power with parallel, intersecting or even skewed axes up to shaft angles of approximately 20°, whereas bevel or hypoid gears are applied with larger shaft angles.Compared with both cylindrical and bevel gears, there is less knowledge available concerning the design of beveloid gears. Existing tools for contact analysis are based on predetermined main gearing data. Therefore a method to pre-dimension main beveloid gearing data based on application requirements was developed. Initially, equivalent cylindrical gears are dimensioned and then transformed into beveloid gears with the required mounting positions. The method involves pre-optimizing of beveloid gears with several targets. Firstly, to comply with selected boundaries of the addendum modification coefficient, as well as to minimize ease-off between the tooth flanks achieved by a centric contact pattern and ensure adequate tip clearance by reducing tip circles.The method was implemented in a software environment for tooth contact analysis and applied to a wide range of data sets. The evaluation demonstrated the efficient design of the main data of beveloid gears including pre-optimization to achieve the objectives mentioned previously. In further optimizations, the microgeometry of beveloid gears must be adapted regarding the gap that occurs between the flanks.     

Immersed particle method for fluid–structure interaction

A method for treating fluid–structure interaction of fracturing structures under impulsive loads is described. The coupling method is simple and does not require any modifications when the structure fails and allows fluid to flow through openings between crack surfaces. Both the fluid and the structure are treated by meshfree methods. For the structure, a Kirchhoff–Love shell theory is adopted and the cracks are treated by introducing either discrete (cracking particle method) or continuous (partition of unity‐based method) discontinuities into the approximation. Coupling is realized by a master–slave scheme where the structure is slave to the fluid. The method is aimed at problems with high‐pressure and low‐velocity fluids, and is illustrated by the simulation of three problems involving fracturing cylindrical shells coupled with fluids. Copyright © 2009 John Wiley & Sons, Ltd.     

An efficient optimization approach for designing machine learning models based on genetic algorithm

Neural Computing and Applications - Machine learning (ML) methods have shown powerful performance in different application. Nonetheless, designing ML models remains a challenge and requires further...     

A dynamic XFEM formulation for crack identification

Nelder–Mead (NM) and Quasi-Newton (QN) optimization methods are used for the numerical solution of crack identification problems in elastodynamics. Fracture is modeled by the eXtended Finite Element Method. The Newmark-β method with Rayleigh damping is employed for the time integration. The effects of various dynamical test loads on the crack identification are investigated. For a time-harmonic excitation with a single frequency and a short-duration signal measured along part of the external boundary, the crack is detected through the solution of an inverse time-dependent problem. Compared to the static load, we show that the dynamic loads are more effective for crack detection problems. Moreover, we tested different dynamic loads and find that NM method works more efficient under the harmonic load than the pounding load while the QN method achieves almost the same results for both load types.     

An integration of production management rules and fabrication know-how for real-time cell production control

Between the steps of operation release and process control of the production activity control, no re-evaluation of the production organization is undertaken. However, the production organization can be technically optimized or modified. This level of production management is difficult to achieve, essentially because several fields come into play. It becomes apparent, however, that it is essential to integrate production management and production cell control in order to obtain advanced production systems which are more ‘reactive’ to technical and economic perturbations. In this paper, a contribution to the resolution of this problems is presented and the following ideas are introduced:

1. a control structure of production cells within “real-time production management functions”,

2. a control strategy of the cells by “scénario de production” (production scenario).

First of all, the functions of this control structure are described and then the principles of its generic utilization for the control of a complex production system are given. An executable production scenario is conceived according to the production management rules, the data and know-how of the fabricators also play a role. The last section of this paper describes, using an industrial example in the field of sub-contracted machining, the construction of such a scenario.     

A study of the service quality of general portals

An Internet portal provides not only a linkage to Web sites but also an entry point to information services. To be successful, it needs to attract a large volume of visitors and consistently deliver a high level of service quality. However, we believe that the service quality of Internet portals, differentiated into business and general portals, should be measured by different instruments, as they are used for different purposes. We conducted two studies employing exploratory factor analysis and confirmatory factor analysis to identify an instrument to measure the service quality of general portals. The results indicated that the instrument is a four-factor model that includes adequacy of information, appearance, usability, and privacy and security. However, only the first two factors are significantly associated with customer satisfaction. Also, it was noted that Web page appearance was not significant for business portals but was for general portals.     

Influence of storage conditions on aroma compounds in coffee pads using static headspace GC–MS

Static headspace gas chromatography coupled to mass spectrometry (SHGC–MS) was used to identify aroma compounds in coffee pad powder. Based on the peak areas of these aroma compounds, the influence of the type of original package on the time of evolution was studied. Statistical ANOVA indicated that coffee pads which were individually packed and hermetically sealed lost less aroma compounds than did pads which were enclosed together in an open package. In addition, coffee pads from an open package were stored in closed plastic bottles at two different temperatures. Storing the pads at 4 °C instead of keeping them at room temperature had a positive influence on the evolution of aroma compounds with time.