Parameterized thermal macromodeling for fast and effective design of electronic components and systems

We present a parameterized macromodeling approach to perform fast and effective dynamic thermal simulations of electronic components and systems where key design parameters vary. A decomposition of the frequency-domain data samples of the thermal impedance matrix is proposed to improve the accuracy of the model and reduce the number of the computationally costly thermal simulations needed to build the macromodel. The methodology is successfully applied to analyze the impact of layout variations on the dynamic thermal behavior of a state-of-the-art 8-finger AlGaN/GaN HEMT grown on a SiC substrate

Technical Description of the implementation of IR7 section at LHC with the FLUKA transport code.

This document contains the technical description of the LHC IR7 FLUKA implementation. It has been written as a handbook to analyze, understand or modify the heat deposition Monte Carlo calculations performed for a wide variety of objects in the IR7 section of the LHC accelerator, in construction at CERN. The work includes references to the prototyping schemes and the implementation of a complex set-up for FLUKA, which deals with lists of objects and properties defined in the Twiss parameters through the use of the LATTICE concept and of a broad collection of user written subroutines

FLUKA simulations for the optimization of the Beam Loss Monitors

The collimation system in the beam cleaning insertion IR7 of the Large Hadron Collider (LHC) is expected to clean the primary halo and the secondary radiation of a beam with unprecedented energy and intensity. Accidental beam losses can therefore entail severe consequences to the hardware of the machine. Thus, protection mechanisms, e.g. beam abort, must be instantaneously triggered by a set of Beam Loss Monitors (BLM's). The readings in the BLM's couple the losses from various collimators, thus rendering the identification of any faulty unit rather complex. In the present study the detailed geometry of IR7 is upgraded with the insertion of the BLM's, and the Monte Carlo FLUKA transport code is used to estimate the individual contribution of every collimator to the showers detected in each BLM

A clinical study of motor evoked potentials using a triple stimulation technique

Amplitudes of motor evoked potentials (MEPs) are usually much smaller than those of motor responses to maximal peripheral nerve stimulation, and show marked variation between normal subjects and from one stimulus to another. Consequently, amplitude measurements have low sensitivity to detect central motor conduction failures due to the broad range of normal values. Since these characteristics are mostly due to varying desynchronization of the descending action potentials, causing different degrees of phase cancellation, we applied the recently developed triple stimulation technique (TST) to study corticospinal conduction to 489 abductor digiti minimi muscles of 271 unselected patients referred for possible corticospinal dysfunction. The TST allows resynchronization of the MEP, and thereby a quantification of the proportion of motor units activated by the transcranial stimulus. TST results were compared with those of conventional MEPs. In 212 of 489 sides, abnormal TST responses suggested conduction failure of various degrees. By contrast, conventional MEPs detected conduction failures in only 77 of 489 sides. The TST was therefore 2.75 times more sensitive than conventional MEPs in disclosing corticospinal conduction failures. When the results of the TST and conventional MEPs were combined, 225 sides were abnormal: 145 sides showed central conduction failure, 13 sides central conduction slowing and 67 sides both conduction failure and slowing. It is concluded that the TST is a valuable addition to the study of MEPs, since it improves detection and gives quantitative information on central conduction failure, an abnormality which appears to be much more frequent than conduction slowing. This new technique will be useful in following the natural course and the benefit of treatments in disorders affecting central motor conductio

Optimization of the active absorber scheme for the protection of the Dispersion Suppressor

There are two main types of cold elements in IR7: quadrupole and dipole magnets (MQ and MB). According to predictions, these objects are to lose their superconducting properties if the spurious power densities reach about 1 and 5 mW/cm3, respectively. In order to protect these fragile components, 5 active absorbers (TCLA) were designed and a systematic study was launched to maximize the shielding efficiency of the absorber system for different configurations (locations and orientations). The TCLA's are identical to the secondary collimators (TCS), the only difference is found in the material of the jaw, which, initially, was set integrally to Cu (instead of C) and later included a small W insertion. This report summarizes the survey of cold element protection through TCLA insertion optimization

Transport processes in TlI and in the AgI-TlI-system

The transport properties of TlI and the system AgI-TlI were investigated by measuring the electrical conductivity, sigma, and the electronic and ionic transport numbers. A particularly high electronic conductivity was detected in beta-TlI, while the alpha phase showed a predominant anionic contribution, as in TlCl and TlBr. The intermediate compounds, AgTl 2I 3 and AgTlI 2 , are silver ion conductors, but they exhibit low sigma values. A comparison with other polyiodides, with a high silver ion conductivity, is suggested on the basis of the crystal bond ionicity

Thermoelectric power and electric conductivity of the (Ag,Na)Cl and (Ag,Na)Br solid solutions

The electric conductivity and the initial thermoelectric power are determined for the solid solutions (Ag,Na)X (X=Cl,Br) over the whole composition range. Data drawn from both kinds of measurements allow to approximately estimate the contributions of cation vacancies and interstitial Ag + to the transport process. Two composition regions are distinguished: 0les NNaXles0.6 and 0.7< NNaX<1 where interstitial Ag + and cation vacancies, respectively, are prevailin