Recent Patents on Engineering - Volume 3, Issue 2, 2009

Artificial neural networks (ANN) is a mathematical model which offers the possibility to develop such a global and integrated approach, without providing any physical explanation for the relationships that have to be validated from a physical point of view. The design of neural networks structures is an important problem for ANN applications which is difficult to solve theoretically. The definition of optimal network architecture for any particular problem is quite difficult and remains an open problem. This work intends to describe a pruning method to optimize the architecture: optimal brain surgeon (OBS). This method balances the accuracy and the time complexity to achieve better neural networks performance. In order to validate the approach, results need to be consistent with experimental data and the rather large tolerance permits the applicability of the methodology. Root mean square error (RMSE) values were small (i.e. < 0.05), thus the network output for each test pattern was relatively close to the respective targets. Artificial neural network is a powerful statistical procedure permitting to relate the parameter of a given problem to its desired result by considering a complex network of neurons. The ANN architecture (neurons number on hidden layer, weights connection, etc.) optimization was pruned by OBS. This method deleted and adjusted weights within a reasonable time, while the unit-OBS method accelerated convergence by deleting one neuron at a time.

Magnetic fluid seal is a special kind of hermetical device. It seals gas or liquid by the sealing ring which is formed when magnetic fluid is placed in the designed strong magnetic field. Such seal has the advantages of simple design, low friction and zero leakage at almost any rotation speed. For better understanding the principle of magnetic fluid seal, some related knowledge of magnetic fluid is presented. On the basis of that, the principle and structure of typical magnetic fluid seal are introduced. Then, a review of the various types of magnetic fluid seals is presented. Its brief history is also reviewed. This is followed by retrospection of some latest patents and applications in magnetic fluid seals. The patents and applications concern a period extending from the years 2003 up to date. The patents principally concern innovative designs of magnetic fluid seal's structure and arrangement. The applications mentioned in this paper mainly focus on areas of high-tech, such as wafer treatment equipment, weber processing apparatus, immersion lithography, Xray apparatus, and so on. At last, a description of the future developments expected in magnetic fluid seal is concluded.

This article gives a patent review of mobile robot control technologies based on vision. It describes the four categories of vision-based robot control: position-based, image-based, hybrid, and motion-based control schemes. The family tree of mobile robot control technologies is given with corresponding explanation that includes independent control, centralized/decentralized control, torque control, force control, hybrid position/force control, and impedance control. The following issues are elaborated: multiple unmanned vehicle techniques, collective control of mobile robots using vision, visual servo control, and vision-based tracking control.

Optimization of Liquid Composite Molding (LCM) processes using Darcy flow numerical simulation requires inputting accurate reinforcement permeability data. Historically introduced by its author to describe infiltration phenomenon, permeability coming from Darcy's law is usually used in LCM processes as a rheological parameter in order to predict the macroscopic resin motion during the filling stage. Resulting from the flow through a complex fibrous architecture, its measurement is very sensitive to the test conditions due to the high filaments flexibility and mesostructure heterogeneity. Reinforcements are currently anisotropic fibrous media and their in-plane permeability measurement requires specific facilities. Measurements can be performed in transient or steady state conditions, and in one-, two- or three-dimensional configurations. This paper describes the different existing experimental configurations, identification procedures and instrumentation techniques. Advantages and drawbacks of each method are discussed, in the particular case of 2D transient measurements, which are the most representative of Resin Transfer Molding process. Two recent patents using different instrumentation techniques are detailed. They are focused on the simultaneous identification of the in-plane principal permeability values in an anisotropic fibrous reinforcement. Some perspectives are suggested to improve the repeatability of such measurement results.

Automatic tool changer (ATC) is a device which can automatically perform tool changes between the spindle and the tool magazine according to the commands given by the machine control unit. It plays an important role in reducing the machine idle time, and leads to an increase in productivity in the machining process. Here, the tool magazine and the tool change mechanism which are the main components of ATC are presented. According to the structures of ATC, we classify it as four types for review: turret-type ATC, cam drive ATC, multi-axis spindle ATC and changing tools in cutting ATC. This paper reviews various recent patents in tool magazines, tool change mechanisms and different types of ATC as well as their applications in machine tool and robot, the patents reviewed concern a period extending from the years 2002 up to date. The patents included in this review refer mainly to the characteristics of ATC which includes armless ATC, turret-type ATC, cam drive ATC, multi-axis spindle ATC, and so on. The applications concern mainly machining center, universal milling machine, drilling machine, router, lathe, miller and robot. In the last part of the review, the future developing trend in ATC and the potential engineering applications are also proposed.

The knowledge of photoinduced absorption spectrum gives important information about the material defect structure, which largely determines its properties and practical application. This article reviews the developments and patent literature in the area of photothermal methods modified for measurement steady state and temporal behavior of light-induced (photoinduced) absorption in bulk materials and thin films. These noncontact methods are characterized with high sensitivity, temporal and spatial resolution and successfully expand traditional techniques. A number of various schemes of photothermal methods were modified for light-induced absorption measurement where compared. Every item has its advantages as well as disadvantages. The results of analysis show that existing photothermal technique is a promising solution to meet the size, simplicity of operation, inexpensiveness, possibilities, and cost requirements of this technique.

Full text available