Measuring the upset of CMOS and TTL due to HPM-signals

To measure the performance of electronic components when stressed by High Power Microwave signals a setup was designed and tested which allows a well-defined voltage signal to enter the component during normal operation, and to discriminate its effect on the component.</p><p style=&quot;line-height: 20px;&quot;> The microwave signal is fed to the outside conductor of a coaxial cable and couples into the inner signal line connected to the device under test (DUT). The disturbing HF-signal is transferred almost independent from frequency to maintain the pulse shape in the time domain. The configuration designed to perform a TEM-coupling within a 50 Ohm system prevents the secondary system from feeding back to the primary system and, due to the geometrical parameters chosen, the coupling efficiency is as high as 50–90%. Linear dimensions and terminations applied allow for pulses up to a width of 12ns and up to a voltage level of 4–5 kV on the outside conductor. These pulse parameters proved to be sufficient to upset the DUTs tested so far.</p><p style=&quot;line-height: 20px;&quot;> In more than 400 measurements a rectangular pulse of increasing voltage level was applied to different types of CMOS and TTL until the individual DUT was damaged. As well the pulse width (3, 6 or 12 ns) and its polarity were varied in single-shot or repetitive-shot experiments (500 shots per voltage at a repetition rate of 3 Hz). The state of the DUT was continuously monitored by measuring both the current of the DUT circuit and that of the oscillator providing the operating signal for the DUT.</p><p style=&quot;line-height: 20px;&quot;> The results show a very good reproducibility within a set of identical samples, remarkable differences between manufacturers and lower thresholds for repetitive testing, which indicates a memory effect of the DUT to exist for voltage levels significantly below the single-shot threshold

Conservation Laws in Cellular Automata

If X is a discrete abelian group and B a finite set, then a cellular automaton (CA) is a continuous map F:B^X-->B^X that commutes with all X-shifts. If g is a real-valued function on B, then, for any b in B^X, we define G(b) to be the sum over all x in X of g(b_x) (if finite). We say g is `conserved' by F if G is constant under the action of F. We characterize such `conservation laws' in several ways, deriving both theoretical consequences and practical tests, and provide a method for constructing all one-dimensional CA exhibiting a given conservation law.Comment: 19 pages, LaTeX 2E with one (1) Encapsulated PostScript figure. To appear in Nonlinearity. (v2) minor changes/corrections; new references added to bibliograph

Development of an innovative validation strategy of gas–surface interaction modelling for re‑entry applications

Abstract This paper summarises the final synthesis of an ESA technology research programme entitled “Development of an Innovative Validation Strategy of Gas Surface Interaction Modelling for Re-entry Applications”. The focus of the project was to demonstrate the correct pressure dependency of catalytic surface recombination, with an emphasis on Low Earth Orbit (LEO) re-entry conditions and thermal protection system materials. A physics-based model describing the prevalent recombination mechanisms was proposed for implementation into two CFD codes, TINA and TAU. A dedicated experimental campaign was performed to calibrate and validate the CFD model on TPS materials pertinent to the EXPERT space vehicle at a wide range of temperatures and pressures relevant to LEO. A new set of catalytic recombination data was produced that was able to improve the chosen model calibration for CVD-SiC and provide the first model calibration for the Nickel–Chromium super-alloy PM1000. The experimentally observed pressure dependency of catalytic recombination can only be reproduced by the Langmuir–Hinshelwood recombination mechanism. Due to decreasing degrees of (enthalpy and hence) dissociation with facility stagnation pressure, it was not possible to obtain catalytic recombination coefficients from the measurements at high experimental stagnation pressures. Therefore, the CFD model calibration has been improved by this activity based on the low pressure results. The results of the model calibration were applied to the existing EXPERT mission profile to examine the impact of the experimentally calibrated model at flight relevant conditions. The heat flux overshoot at the CVDSiC/PM1000 junction on EXPERT is confirmed to produce radiative equilibrium temperatures in close proximity to the PM1000 melt temperature.This was anticipated within the margins of the vehicle design; however, due to the measurements made here for the first time at relevant temperatures for the junction, an increased confidence in this finding is placed on the computations

Technical note: Whole-pen assessments of nutrient excretion and digestibility from dairy replacement heifers housed in sand-bedded freestalls

Our objectives were to describe and test refined procedures for quantifying excreta produced from whole pens of dairy heifers. Previous research efforts attempting to make whole-pen measurements of excreta output have been complicated by the use of organic bedding, which requires cumbersome analytical techniques to quantify excreta apart from the bedding. Research pens equipped with sand-bedded freestalls offer a unique opportunity for refinement of whole-pen fecal collection methods, primarily because sand-bedded freestall systems contain no organic bedding; therefore, concentrations of ash within the manure, sand, and feces can be used to correct for contamination of manure by sand bedding. This study was conducted on a subset of heifers from a larger production-scale feeding trial evaluating ensiled eastern gamagrass [Tripsacum dactyloides (L.) L.] haylage (EGG) that was incorporated into a corn silage/alfalfa haylage-based blended diet at rates of 0, 9.1, 18.3, or 27.4% of total DM. The diet without EGG also was offered on a limited basis. Eighty Holstein dairy heifers were blocked (heavy weight, 424 ± 15.9 kg; light weight, 324 ± 22.4 kg) and then assigned to 10 individual pens containing 8 heifers/pen. One pen per block was assigned to each of the 5 research diets, and whole-pen fecal collections were conducted twice for each pen. Grab fecal samples also were gathered from individual heifers within each pen, and subsequent analysis of these whole-pen composites allowed reasonable estimates of OM and NDF excreta output. Under the conditions of our experimental design, pooled SEM for the excreta DM, OM, NDF, and NDF (ash corrected) output were 0.113, 0.085, 0.093, and 0.075 kg· heifer –1·d–1, respectively. For DM excretion, this represented about one-third of the SEM reported for previous whole-pen collections from bedded- pack housing systems. Subsequent calculations of apparent DM and OM digestibilities indicated that the technique was sensitive, and linear trends (P ≤ 0.027) associated with the inclusion rates of EGG within the diet were detected. This technique allows estimation of apparent diet digestibilities on multiple animals simultaneously, thereby mitigating the need for isolating individual animals to obtain digestibility coefficients. The approach appears viable but requires hand labor for collections of multiple pens and thorough mixing of large volumes of manure as well as analytical corrections for sand ingested by lounging heifers

Pericardial effusion of HIV-infected patients - results of a prospective multicenter cohort study in the era of antiretroviral therapy

<p>Abstract</p> <p>Background</p> <p>Patients with human immunodeficiency virus (HIV) infection have an increased risk of cardiovascular diseases. Previous publications described pericardial effusion as one of the most common HlV-associated cardiac affiliations. The aim of the current study was to investigate if pericardial effusion still has a relevant meaning of HIV-infected patients in the era of antiretroviral therapy.</p> <p>Methods</p> <p>The HIV-HEART (HIV-infection and HEART disease) study is a cardiology driven, prospective and multicenter cohort study. Outpatients with a known HIV-infection were recruited during a 20 month period in a consecutive manner from September 2004 to May 2006. The study comprehends classic parameters of HIV-infection, comprising CD4-cell count (cluster of differentiation) and virus load, as well as non-invasive tests of cardiac diseases, including a thorough transthoracic echocardiography.</p> <p>Results</p> <p>802 HIV-infected patients (female: 16.6%) with a mean age of 44.2 ± 10.3 years, were included. Duration of HIV-infection since initial diagnosis was 7.6 ± 5.8 years. Of all participants, 85.2% received antiretroviral therapy. Virus load was detectable in 34.4% and CD4 - cell count was in 12.4% less than 200 cells/μL. Pericardial effusions were present in only two patients of the analysed population. None of the participants had signs of a relevant cardiovascular impairment by pericardial effusion.</p> <p>Conclusions</p> <p>Our results demonstrate that the era of antiretroviral therapy goes along with low rates of pericardial effusions in HIV-infected outpatients. Our findings are in contrast to the results of publications, performed before the common use of antiretroviral therapy.</p

A five-year observance of changes in the cardiovascular risk profile in 505 HIV-positive individuals

Purpose: Since the introduction of antiretroviral therapy (ART) and the extension of life expectancy, HIV-infected persons have shown an increasing number of cardiovascular events. The reduction of cardiovascular risk factors becomes a new challenge in HIV care. One of the main objectives of the HIV&amp;HEART study is to examine the development of cardiovascular risk factors and treatment of cardiovascular diseases. Methods: This study is an on-going, prospective, regional multicentre trial that was conducted to analyse the frequency and clinical course of cardiac disorders as well as cardiovascular risk factors in HIV-infected patients. 505 HIV-infected outpatients were recruited at baseline (BL) and re-examined during 5-year follow up (5YFU). Results: 84% of 505 eligible HIV-infected patients were male. The average age was 44.3&#x00B1;9.5 years at BL. The proportion of ART-treated patients increased from 85.7% at BL to 96.4% at 5YFU. During the 5-year observation period mean cardiovascular risk detected by Framingham score increased from 6% at BL to 10% at 5YFU. Even after adjusting for age there was a difference in the Framingham score of 2%. Between BL and 5YFU systolic blood pressure increased from 128.4&#x00B1;19.8 mmHg to 138.3&#x00B1;19.9 mmHg in spite of an intensified use of antihypertensive drugs, from 11.9% at BL to 24.0% at 5YFU. The rate of participants with adiposity, characterised by a BMI&#x3E;30, increased from 7.9% at BL to 11.2% at 5YFU. Lipid-lowering therapy was applied in 10.3% of the patients at BL and in 13.9% at 5YFU. Triglycerides (TAG)&#x2265;200 mg/dl reduced from 38.9% at BL to 36.8% at 5YFU; in contrast cholesterol values&#x2265;200 mg/dl elevated from 57.8% to 61.8%. The same trend was observed in HDL&#x2264;40 mg/dl. Here we found a change from 29.2% versus 31.3%. Doing regular sports elevated from 1.9% to 3.3%. The count of smokers increased for 2.8% and also mean pack-years changes from 24 to 26.5 pack-years. Conclusion: During a 5-year period the cardiovascular risk in Framingham score increased disproportionately high in this HIV-infected cohort even after adjusting for age. There was an increasing blood pressure although an elevated use of antihypertensive therapy. There was also a tendency of elevating BMI and an increasing trend in smoking behavior. As protective facts, we found a tendency in doing sports and a decreasing TAG value during intensifying lipid-lowering therapy. Cardiovascular risk was increasing, in spite of interventions