Spot welding is a complex technological process in which the interaction occurs between the elect... more Spot welding is a complex technological process in which the interaction occurs between the electrical, thermal, mechanical and metallurgical phenomena. Different researchers around the world are studying the problems generated by dilatations and contractions in welded joints and the microstructure changes that cause dangerous internal tensions or unacceptable deformations that affect the quality and reliability of welded products. Were experimented, developed and tested various welding conditions and different materials using both theoretical and experimental methods [1…5]. In this paper are shown the results obtained by dynamic tests applied on specimens subjected to spot welding. The specimens made out of sheet metal for pressing were welded with two different welding regimes. The number and succession of the points execution has varied. In these conditions different internal tensions and deformations was result. For each test specimen to the basic harmonic excitation, the resona...
It has been recently pointed out than the Kalman filter is a powerful tool for the synchronizatio... more It has been recently pointed out than the Kalman filter is a powerful tool for the synchronization of chaos, which remains a major difficulty in the development of efficient chaos based digital communication systems, capable of operating over nonstationnary channels. The input signal power fluctuations, which often causes large errors in synchronizing chaotic waveforms, is discussed in this paper. The
In this article, a new compression method is investigated using a particular chaotic modulation t... more In this article, a new compression method is investigated using a particular chaotic modulation type. The symbolic approach presented associates to every informational sequence a trajectory in the state space of the chaotic generator. We are also introducing a new type of chaotic generator adapted to the probability distribution of the informational sequence, and we prove that using the described
2005 IEEE International Symposium on Circuits and Systems
... I. INTRODUCTION Over the last decade, a great research effort has been devoted towards the de... more ... I. INTRODUCTION Over the last decade, a great research effort has been devoted towards the development of efficient chaos-based modulation tech-niques (see [2]-[4]). This ... Then, the problem of chaos synchronization via nonlinear Kalman filtering is discussed in ...
This paper adresses the problem of symbol estima- tion in the case of a spread spectrum based sys... more This paper adresses the problem of symbol estima- tion in the case of a spread spectrum based system where the receiver has only the information about the nonlinear function used to generate the spreading sequence. We propose two methods to achieve this, first based on the already considered DUAL form and a correlator second based one. For the DUAL form we consider multiple Kalman filter implementations suited to the case of nonlinear estimation methods among them Unscented Kalman Filter (UKF) and Exact Polynomial Kalman Filter (ExPKF). Finaly to provide a perfomance evaluation on the proposed methods we obtain throughout Monte-Carlo simulations the Bit Error Rate (BER) characteristics with respect to Signal to Noise Ratio (SNR).
A full thermal investigation of the 726-microampere Temperature Stabilized Substrate Integrated C... more A full thermal investigation of the 726-microampere Temperature Stabilized Substrate Integrated Circuit (TSS IC) has been performed using a new and accurate quasi-three-dimensional numerical method. This new method allows a reduction of the three-dimensional thermal problem to a bidimensional one. This reduction does not affect the accuracy of the computed temperature distribution of the semiconductor chip. The validity of our
Tools for plastic deformation at hot or cold are made of medium or high alloyed special steels, w... more Tools for plastic deformation at hot or cold are made of medium or high alloyed special steels, which are relatively expensive. To reduce the material costs of these tools, it is possible to manufacture them of low alloyed steels. In this case it was used steel 42CrMo4 (1.7225). The active surface of these tools is carried out by charging a welding wear resistant material. Within the framework of research it was used the VTCr25W4TiLa filler material, made in the form of tubular rod designed for WIG process deposits or oxyacetylene flame of wear-resistant layers. Anti-wear layers made austenitic structure, in which fine carbides of Cr, W and Ti are embedded. These layers are characterized by high abrasion resistance , combined with corrosion resistance and thermomechanical fatigue. Depending on the heat treatment applied can be obtained usable tools for plastic deformation at hot or cold.
Spot welding is a complex technological process in which the interaction occurs between the elect... more Spot welding is a complex technological process in which the interaction occurs between the electrical, thermal, mechanical and metallurgical phenomena. Different researchers around the world are studying the problems generated by dilatations and contractions in welded joints and the microstructure changes that cause dangerous internal tensions or unacceptable deformations that affect the quality and reliability of welded products. Were experimented, developed and tested various welding conditions and different materials using both theoretical and experimental methods [1…5]. In this paper are shown the results obtained by dynamic tests applied on specimens subjected to spot welding. The specimens made out of sheet metal for pressing were welded with two different welding regimes. The number and succession of the points execution has varied. In these conditions different internal tensions and deformations was result. For each test specimen to the basic harmonic excitation, the resona...
It has been recently pointed out than the Kalman filter is a powerful tool for the synchronizatio... more It has been recently pointed out than the Kalman filter is a powerful tool for the synchronization of chaos, which remains a major difficulty in the development of efficient chaos based digital communication systems, capable of operating over nonstationnary channels. The input signal power fluctuations, which often causes large errors in synchronizing chaotic waveforms, is discussed in this paper. The
In this article, a new compression method is investigated using a particular chaotic modulation t... more In this article, a new compression method is investigated using a particular chaotic modulation type. The symbolic approach presented associates to every informational sequence a trajectory in the state space of the chaotic generator. We are also introducing a new type of chaotic generator adapted to the probability distribution of the informational sequence, and we prove that using the described
2005 IEEE International Symposium on Circuits and Systems
... I. INTRODUCTION Over the last decade, a great research effort has been devoted towards the de... more ... I. INTRODUCTION Over the last decade, a great research effort has been devoted towards the development of efficient chaos-based modulation tech-niques (see [2]-[4]). This ... Then, the problem of chaos synchronization via nonlinear Kalman filtering is discussed in ...
This paper adresses the problem of symbol estima- tion in the case of a spread spectrum based sys... more This paper adresses the problem of symbol estima- tion in the case of a spread spectrum based system where the receiver has only the information about the nonlinear function used to generate the spreading sequence. We propose two methods to achieve this, first based on the already considered DUAL form and a correlator second based one. For the DUAL form we consider multiple Kalman filter implementations suited to the case of nonlinear estimation methods among them Unscented Kalman Filter (UKF) and Exact Polynomial Kalman Filter (ExPKF). Finaly to provide a perfomance evaluation on the proposed methods we obtain throughout Monte-Carlo simulations the Bit Error Rate (BER) characteristics with respect to Signal to Noise Ratio (SNR).
A full thermal investigation of the 726-microampere Temperature Stabilized Substrate Integrated C... more A full thermal investigation of the 726-microampere Temperature Stabilized Substrate Integrated Circuit (TSS IC) has been performed using a new and accurate quasi-three-dimensional numerical method. This new method allows a reduction of the three-dimensional thermal problem to a bidimensional one. This reduction does not affect the accuracy of the computed temperature distribution of the semiconductor chip. The validity of our
Tools for plastic deformation at hot or cold are made of medium or high alloyed special steels, w... more Tools for plastic deformation at hot or cold are made of medium or high alloyed special steels, which are relatively expensive. To reduce the material costs of these tools, it is possible to manufacture them of low alloyed steels. In this case it was used steel 42CrMo4 (1.7225). The active surface of these tools is carried out by charging a welding wear resistant material. Within the framework of research it was used the VTCr25W4TiLa filler material, made in the form of tubular rod designed for WIG process deposits or oxyacetylene flame of wear-resistant layers. Anti-wear layers made austenitic structure, in which fine carbides of Cr, W and Ti are embedded. These layers are characterized by high abrasion resistance , combined with corrosion resistance and thermomechanical fatigue. Depending on the heat treatment applied can be obtained usable tools for plastic deformation at hot or cold.
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