161 research outputs found

    The Estimation of Flows on Regional Labour Markets By Using the ADETON Procedure

    Get PDF
    An in-depth analysis of regional labour markets requires information not only on stocks but also on flows. As a tool for detailed flow analysis the Multi Account System (MAS) has been developed at the Institute for Employment Research (IAB) which uses fine grained transition matrices as basic information. To estimate these transition matrices from possibly incomplete and inconsistent statistical data the ADETON procedure has been worked out to compute matrices which are struc-turally similar to given reference matrix and at the same time satisfy certain linear con-straints. As main advantage of ADETON in comparison to conventional methods soft constraints may be specified which allow information of inherently fuzzy character about transition flows to be taken into account. By using soft constraints of this kind it is possible to in-clude data affected by sampling errors or are distorted by some kind of “noiseâ€. To obtain structural similarity to a reference matrix two different distance measures can be used: relative entropy and the chi-square distance function. They have been proven to give approximately identical results. Up to now ADETON has shown to be an efficient computation method even for complex problems with thousands of matrix elements and constraints. ADETON has been applied to estimate matrices of the Multi Account System. The results are used for the guidance of regional labour market policy.

    Hybrid Optimization Based Mathematical Procedure for Dimensional Synthesis of Slider-Crank Linkage

    Get PDF
    In this paper, an optimization procedure for path generation synthesis of the slider-crank mechanism will be presented. The proposed approach is based on a hybrid strategy, mixing local and global optimization techniques. Regarding the local optimization scheme, based on the null gradient condition, a novel methodology to solve the resulting non-linear equations is developed. The solving procedure consists of decoupling two subsystems of equations which can be solved separately and following an iterative process. In relation to the global technique, a multi-start method based on a genetic algorithm is implemented. The fitness function incorporated in the genetic algorithm will take as arguments the set of dimensional parameters of the slider-crank mechanism. Several illustrative examples will prove the validity of the proposed optimization methodology, in some cases achieving an even better result compared to mechanisms with a higher number of dimensional parameters, such as the four-bar mechanism or the Watt’s mechanism.The authors wish to acknowledge financial support received from the Spanish government through the Ministerio de Economía y Competitividad (Project DPI2015−67626-P (MINECO/FEDER, UE)), the support for the research group through Project Ref. IT949−16, provided by the Departamento de Educación, Política Lingüística y Cultura from the regional Basque Government, and the Program BIKAINTEK 2020 (Ref. 012-B2/2020) provided by the Departamento de Desarrollo Económico, Sostenibilidad y Medio Ambiente from the regional Basque Government

    Position Tracking Of Slider Crank Mechanism Using Pid Controller Optimized By Ziegler Nichol’s Method

    Get PDF
    This paper presents a study on the position tracking response of a Propotional-Integral-Derivative (PID) controlled- slider crank mechanism, which is driven by a two phase stepper motor. In this study, the rod and crank are assumed to be rigid where the Newton second law is applied to formulate the equation of motion. A position tracking control of the slider crank mechanism is then developed by using PID controller. Several tests such as saw tooth, step function and square function are used in order to examine the performance of the proposed control structure. The results show that, the proposed control structure is able to tracking the desired position with a good response. The slider crank mechanism rig is then developed to investigate experimentally the ability of the proposed controller structure. The results show that the proposed control structure is able to track the desired displacements with accepTABLE error

    Optimal synthesis of planar adjustable mechanisms

    Get PDF
    Adjustable mechanisms provide degrees of flexibility while retaining desirable features of one degree of freedom close-loop mechanisms, such as simplicity, stability, and high speed capabilities. By adjusting linkage parameters, additional phases of motions can be achieved using the same hardware. However, an adjustment to the mechanism adds only one or two additional design positions and divides desired positions into phases , each of which contains only a few positions usually insufficient for industrial applications. In order to extend the design position limitation of adjustable mechanisms, an optimal synthesis method based on link length structural error is developed and applied to kinematic synthesis of adjustable planar mechanisms in this research. Designed with this method, adjustable mechanisms can achieve phases of many design positions with a minimized error. The conveniently-calculated link length structural error effectively reflects the overall difference between generated and desired motions without directly comparing them; and its compact fourth-order polynomial form facilitates the gradient- based optimization process. Link length structural error based optimal synthesis methods are developed for adjustable planar four-bar mechanisms for three typical synthesis tasks. For multi-phase approximate motion generation, standard optimization model is established based on adjustable optimal dyads considering all types of adjustments. For multi-phase continuous path generation, a proper driving dyad is firstly found by an optimization procedure using the full rotation requirement. The driven dyad is then found using the optimization technique for motion generation after calculating all coupler angles. For multi-phase function generation, the coupler length is chosen to carry the structural error and adjustments to the coupler and the side-link lengths are considered. Numerical synthesis examples have demonstrated that the developed method is effective and efficient for multi-phase motion, path, and function generation of planar four-bar linkages with a large number of specified positions in each phase

    Face recognition/clustering - performance improvements, 2007

    Get PDF
    This thesis will introduce Face Recognition as an important and crucially needed type of biometrics. The existing and most widely used Face Recognition algorithms have been tested and the results will be presented. Additionally, the limitations of the existing FF methods will be discussed, focusing chiefly on the future of Face Recognition and the reasons such relatively poor results were achieved in comparison with results from other Biometrics. Finally, a novel system that enhances the performance of the face matching for existing FF algorithms (High-speed k-means Image Clustering using the Discrete Cosine Transform and its comparison with existing methods) will be discussed. Appendix A focuses on the results obtained from the Haar face detection algorithm, utilizing different face databases. Appendix B is dedicated to the Matlab code

    The 1st Conference of PhD Students in Computer Science

    Get PDF
    corecore