Experimental power cycling on insulated TRIAC package: Reliability interpretation thanks to an innovative failure analysis flow

This paper presents the insulated TO-220AB TRIAC package aging when these devices are subjected to experimental power cycling test with various case temperature swings (ΔT_case). This study includes reliability tests set-up, results and failure analysis. An innovative failure analysis flow is proposed to identify the failure mechanism implied. This new failure analysis process flow is necessary due to the complex stack of these devices. Finally, thanks to the reliability tests and the complete failure analysis results, the thermal resistance (R_th) change is correlated to the physical defect modification. This whole study gives the first data collection that is required to propose a lifetime prediction model for insulated TO-220AB TRIAC package during power cycling accelerated aging tests.     

A Survey on IP Watermarking Techniques

Intellectual property (IP) block reuse is essential for facilitating the design process of system-on-a-chip. Sharing IP designs poses significant high security risks. Recently, digital watermarking emerged as a candidate solution for copyright protection of IP blocks. In this paper, we survey and classify different techniques used for watermarking IP designs. To this end, we defined several evaluation criteria, which can also be used as a benchmark for new IP watermarking developments. Furthermore, we established a comprehensive set of requirements for future IP watermarking techniques.     

Microwave active resonator band-pass filters in various mmic technologies

In this article, two topologies of L-C parallel active resonators are presented. These circuits are realized in MMIC technology, using three transistors which could be MESFET, hemt or HBT. The survey of these resonators shows the possibility, by controling the values of a resistor and/or a capacitor, on the one hand, to tune the resonance frequency of these circuits, and on the other hand, to cancel out their losses so as to obtain negative conductance. Compact, lossless and narrow-band filters are then implemented using previous active resonators. To date, the use of mesfet technology has reduced the synthesis of such active filters in S-band and at X-band low frequencies. Now, however, hemt and HBT technologies allow the extension of their implementation to the whole X-band. This survey is illustrated by the simulated response of a 10 GHz filter with a 500 MHz 3 dB bandwidth. The mmic technology is a 0.2 μm hemt one. The simulated performances of this filter achieve a mean transmission gain of 0. 5 dB, with a reflection loss higher than 10 dB at 10 GHz,     

Compositional, structural, optical and electrical characterization of CulnTe2 grown by the tellurization of stoichiometric Cu and in in the liquid phase

A new method to grow single crystals with stoichiometry close to 1:1:2 of CuInTe₂, an important member of the Cu-III-VI₂ family of semiconductors is described. This consists of tellurization in the liquid phase of stoichiometric Cu and In and later solidification under directional freezing. It is found from energy dispersive spectroscopy that the ingots obtained with the evaporation temperature (T_t) of Te at 590 and 635°C were very close to the ideal stoichiometry 1:1:2. Samples of all ingots obtained with T_t between 530 and 690°C, as studied by x-ray and differential thermal analysis, were of single phase having chalcopyrite structure and p-type conductivity. Optical and electrical characterization of different ingots were made. The acceptor ionization energy E_A and the density of states effective mass m _p ^* of the holes are estimated from the temperature dependence of the hole concentration p in samples of different ingots. m _p ^* = (0.78 ± 0.02) m_e agrees quite well with the reported value. From a combined analysis of the variation of E_A with p^1/3 and the knowledge of molecularity and valence stoichiometry of each sample, it is established that the shallow acceptor level observed in different samples with E_A (0) ⋍ 30 meV is due to V_In.     

Copper-induced changes in the properties of arsenic chalcogenides

The influence of the presence of Cu in the amount between 1% and 6% in arsenic chalcogenide glasses is examined through a study of the electronic energy levels by means of x-ray photoelectron and x-ray emission spectroscopy, through an investigation of the low-energy tunneling systems by means of phonon echoes at 0.37 K, and through an examination of the photodarkening and the photoinduced dichroism caused by polarized Ar⁺ laser irradiation. Possible links between the various effects are examined. The Cu atoms become an integral part of the amorphous lattice structure and strongly influence the photodarkening, but they do not have a significant effect on the tunneling systems or the dichroism. It is concluded that the tunneling levels and the dichroism involve only local configurations, while the photodarkening involves larger-scale areas of the lattice. Fiz. Tekh. Poluprovodn. 32, 976–981 (August 1998)     

Thermal Monitoring of Self-Checking Systems

With the increasing power density in integrated systems resulting from scaling down, the occurrence of field failures due to overheating has considerably increased. Faulty operation can be prevented by on-line temperature monitoring. This paper deals with questions of on-line temperature monitoring in safety-critical systems. First the possible temperature sensors are reviewed and basic principles of self-checking systems including such sensors are detailed, then a new temperature sensor cell with extremely good parameters designed especially for DfTT applications is presented. The basic questions of integrating thermal sensors into self-checking systems are also discussed.     

An Extraction of the Dominant Rotor-Stator Interaction Modes by the Use of Proper Orthogonal Decomposition （POD）

The Proper Orthogonal Decomposition method is applied to the instantaneous velocity field within the rotor-stator inter-row region of a high-speed high-pressure centrifugal compressor. The processed data come from experiments and numerical simulations. In comparison with a Fourier transform, the POD gives the best modal approximation for both initial fields, in terms of the energy expressed on any given number of modes to be taken into account: to reach 98% of the total energy of the velocity field, the required number of POD modes is around nine times smaller than the number of Fourier harmonics. The individual POD modes are given and show that the unsteady rotor-stator interaction is already present in the very first modes.     

Hypergeometric Functions and Parabolic Partial Differential Equations

We investigate the summability of formal power series solutions of parabolic linear partial differential equations with exponential coefficients.2000 Mathematics Subject Classification. 35C10, 35C20.This research was supported by a Marie Curie Fellowship of the European Community program Improving Human Research Potential under contract number HPMF-CT-2002-01818.     

Unsteady rotor-stator interaction in high speed compressor and turbine stages

The blade row interaction can alter the time-mean flow and therefore be of interest for aerodynamic design analysis. Whereas results within low subsonic turbomachines are quite numerous in the literature, there have been far fewer works which give results of blade row interaction within high speed cases. Two cases are related in this paper. First, the effects of an incoming wake on the rotor flow field of a transonic compressor are analyzed. The blade row interaction proved to be positive regarding the total pressure ratio, but negative regarding the losses. The second case concerns a transonic turbine. Particular emphasis is placed on the assessment of the deterministic correlations included in the Averaged Passage Equation System.     

Steam conditioning after low temperature dyring

The purpose of this study was to investigate the response of saturated water vapour steaming on boards from Scots pine and Norway spruce. Steaming treatment of the predried boards were done in a laboratory chamber equipped with a 1.5 kW electric water boiler. The experiments were performed mainly at 100°C in saturated steam and the relation between temperature and moisture pickup as well as stress relaxation was studied. The results showed that steaming is a very efficient process to relax stress and equalise moisture gradients in boards. The gain of time is considerable; steaming takes only about 10% of traditional conditioning time at lower temperatures. The temperature rise is correlated to moisture pickup from surface condensation resulting in the possibility of estimating the increase of moisture content during steaming from measurements of temperature.