Theoretical and Experimental Analysis of Resistor Network for Use in Superconducting Analog-to-Digital Applications

Superconducting micro-electronics (SME) technology is capable of realizing extremely high speed digital receivers performing direct digitization of microwave signals with very low power consumption. SME technology uses integrated circuits based on Josephson junctions and rapid single-flux quantum (RSFQ) logic operating at 4°K. The analogue-to-digital converter (ADC) is a basic building block of such receivers. Quantization and sampling are two fundamental parts of ADCs. Flash ADCs are the fastest converters and consist of comparators and a resistor network. This thesis investigates the use of a multi-layer niobium-based low-temperature superconducting process to implement a resistor network. Several configurations for resistors are investigated both electrically and thermally. The resistors are designed to maintain their values from DC to 50GHz. Floating metal structures are added and optimized to minimize the inductance of the structure in order to obtain frequency-independent resistors over a frequency range of 50GHz. Several resistors and R-2R ladder networks are fabricated in the same process and measured in an RF cryogenic probe station at the Centre for Integrated RF Engineering (CIRFE) Lab at the University of Waterloo. Theoretical thermal analysis, is also carried out for these resistors to investigate temperature variations through the structures when operating at different power levels. The investigation is important for making sure that the resistors’ dissipated heat does not raise the local temperature above the transition temperature of niobium

Individual-Based Modeling and Nonlinear Analysis for Complex Systems with Application to Theoretical Ecology

One approach to understanding the behaviour of complex systems is individual-based modeling, which provides a bottom-up approach allowing for the consideration of the traits and behaviour of individual organisms. Ecosystem models aim to characterize the major dynamics of ecosystems, in order to synthesize the understanding of such systems and to allow predictions of their behaviour. Moreover, ecosystem simulations have the potential to help scientists address theoretical questions as well as helping with ecological resource management. Because in reality biologists do not have much data regarding variations in ecosystems over long periods of time, using the results of ecological computer simulation for making reasonable predictions can help biologists to better understand the long-term behaviour of ecosystems. Different versions of ecosystem simulations have been developed to investigate several questions in ecology such as how speciation proceeds in the absence of experimenter-defined functions. I have investigated some of these questions relying on complex interactions between the many individuals involved in the system, as well as long-term evolutionary patterns and processes such as speciation and macroevolution. Most scientists now believe that natural phenomena have to be looking as a chaotic system. In the past few years, chaos analysis techniques have gained increasing attention over a variety of applications. I have analyzed results of complex models to see whether chaotic behaviour can emerge, since any attempt to model a realistic system needs to have the capacity to generate patterns as complex as the ones that are observed in real systems. To further understand the complex behaviour of real systems, a new algorithm for long-term prediction of time series behaviour is also proposed based on chaos analysis. We evaluated the performance of our new method with respect to the prediction of the Dow-Jones industrial index time series, epileptic seizure and global temperature anomaly

KARTIRANJE LISKUNASTE ŽELJEZNE RUDE I IZRADA PRIMJENJIVIH INDUSTRIJSKIH STANDARDA

The purpose of this study is to determine the appropriate method for micaceous iron ore processing and production per-industrial application standards. After identifying the characteristics of the samples (with XRF, XRD, mineralogical analyzes), gravity and magnetic separation tests were carried out. Quartz and hematite are the main minerals of micaceous hematite ores. Silica grade as the major impurity varies from 10% to 68%. The total iron content of the samples also varies from 15% to 62%. A jig and shaking table did not provide a good result in micaceous hematite beneficiation to achieve the standard of its specific applications. Gravity concentration by the spiral in the size range of -200 and -300 μm has led to the production of iron concentrates with a grade of 62.34% and 64.84%, respectively. The recovery values for the two experiments are 13.50% and 12.60%, respectively. Therefore, the spiral did not provide a good result in the micaceous iron ore beneficiation. High-intensity magnetic separation (1.2 T) has resulted in a product with a grade and recovery of 65.98% and 88.35%, respectively. The experimental design utilizing the Taguchi method considering the increasing of grade or recovery priority indicated that for micaceous iron beneficiation with a priority of recovery increasing, the feeder frequency, roll speed, and adjustable gate angle should be at 6.5 Hz, 95 rpm, and 20°, respectively. However, for micaceous iron beneficiation with a priority of grade increasing, the feeder frequency, roll speed, and adjustable gate angle should be at 2.5 Hz, 135 rpm, and 60°, respectively.Svrha je ovoga istraživanja odrediti prikladnu metodu za oplemenjivanje liskunaste željezne rude te izrada standarda primjenjivih u industriji. Nakon utvrđivanja karakteristika uzoraka (s XRF, XRD, mineraloškim analizama) provedena su ispitivanja gravitacijskom i magnetskom separacijom. Kvarc i hematit glavni su minerali liskunastih hematitnih ruda. Udio silicija kao glavne nečistoće varira od 10 % do 68 %. Ukupni sadržaj željeza u uzorcima također varira od 15 % do 62 %. Plakalica i koncentracijski stol nisu dali dobre rezultate u obogaćivanju liskunastoga hematita za postizanje standar-da njegove specifične primjene. No, gravitacijska koncentracija spiralom veličine zrna -200 i -300 μm rezultirala je kvali-tetom koncentrata željeza od 62,34 odnosno 64,84 %. Vrijednosti iskorištenja bile su 13,50 odnosno 12,60 %. Stoga ni spirala nije dala dobar rezultat u obogaćivanju liskunaste željezne rude. Visokointenzivna magnetska separacija (1,2 T) rezultirala je kvalitetom koncentrata od 65,98 % i iskorištenjem od 88,35 %. Eksperimentalni dizajn prema Taguchiju s obzirom na povećanje kvalitete ili iskorištenja pokazao je da za povećanje iskorištenja frekvencija dodavača, brzina bub-nja i kut separacijskoga noža trebaju biti na 6,5 Hz, 95 o/min i 20°. Međutim, za obogaćivanje liskunaste željezne rude s prioritetom povećanja kvalitete koncentrata frekvencija dodavača, brzina bubnja i kut separacijskoga noža trebaju biti 2,5 Hz, 135 o/min, odnosno 60°

Spontaneous Coronary Artery Dissection: A Rare Event?

Spontaneous coronary artery dissection is an infrequent cause of acute coronary syndrome with comparable clinical features. Previously considered a rare disease, recent scientific interest has revealed spontaneous coronary artery dissection as an important differential diagnosis of acute coronary syndrome, especially in young women, during pregnancy or postpartum, and in patients with fibromuscular dysplasia or other arteriopathies. However, there remain many uncertainties regarding pathophysiology, risk factors, acute treatment, and optimal long-term management. The aim of this review is to summarize current scientific evidence on epidemiology, management, and outcomes

Takotsubo Syndrome: Uncovering Myths and Misconceptions

PURPOSE OF REVIEW Takotsubo syndrome (TTS) was described in Japan 3 decades ago to affect predominately postmenopausal women after emotional stress. This history is the basis of commonly held beliefs which may contribute to the underdiagnosis and misperception of TTS. RECENT FINDINGS TTS affects not only women, but can be present in both sexes, and can appear in children as well as in the elderly. TTS is characterized by unique clinical characteristics with morphological variants, and incurs a substantial risk for recurrent events and adverse outcomes. Physical triggers are more common than emotional triggers and are major disease determinants. TTS seems not to be completely transient as patients report ongoing chest pain, dyspnea, or fatigue even after months of the acute event. Knowledge of the clinical features and outcomes of TTS patients has evolved substantially over the past decades. The heterogeneous appearance of TTS needs to be recognized in all medical disciplines to maximize therapy and improve outcomes

ISPIRANJE ŽELJEZA IZ SIROMAŠNE RUDE BOKSITA U CILJU NJEZINE UPORABE U VATROSTALNOJ INDUSTRIJI

Iron-bearing minerals are the most important interfering compounds that are found with bauxite reserves. The element iron has adverse effects on bauxite applications, including the use of bauxite in refractory soils. The purpose of this research is to investigate the possibility of iron removal from low-grade bauxite ores to utilize them in refractory industries. For achieving this purpose, iron removal tests were performed on bauxite samples with an alumina to silica modulus of 0.73. After determining the appropriate iron removal method among the magnetic separation, calcination, and leaching (with H2SO4 and HCl) processes, optimal separation conditions were determined by tests that were designed using the Taguchi method. According to leaching results, using HCl for raw feed (un-calcined) provided the best result for iron removal. During this test, Fe2O3 grade decreased from 5.14% to 0.08%, and the alumina to silica modulus increased to 0.75. Calcination of the concentrate obtained from this test has led to favorable results in reducing the Fe2O3 grade (0.04%) and increasing the Al2O3 grade. Afterwards, in tests designed by the Taguchi method, the effect of parameters such as time, process temperature, HCl concentration, and feed grain size on iron removal from bauxite by HCl leaching processes are discussed. According to the results, the best efficiency of iron removal for a feed grain size of 250 µm is achieved in the following conditions: 30% HCl, process temperature of 25°C, and process time of 120 minutes. In this case, iron removal efficiency and Fe2O3 grade in process concentrate are 92.78% and 0.56%, respectively.Minerali nosioci željeza najvažnije su nečistoće koje se nalaze u rezervama boksita. Željezo ima štetne učinke na primjenu boksita, uključujući korištenje boksita u vatrostalnim tlima. Svrha je ovoga rada istražiti mogućnost uklanjanja željeza iz ruda boksita niske kvalitete radi iskorištavanja u vatrostalnoj industriji. U tu svrhu provedena su ispitivanja izdvajanja željeza na uzorcima boksita s modulom aluminijeva oksida i silicija od 0,73. Nakon utvrđivanja odgovarajuće metode za izdvajanje željeza, uključujući magnetsku separaciju, kalcinaciju i luženje (s H2SO4 i HCl), određeni su optimalni uvjeti izdvajanja uz upotrebu Taguchijeve metode. Rezultati luženja HCl-om rovne sirovine (nekalcinirane) dali su najbolji rezultat izdvajanja željeza. Tijekom ovoga ispitivanja udio Fe2O3 smanjio se s 5,14 % na 0,08 %, a modul aluminijeva oksida i silicija povećao se na 0,75. Kalciniranje koncentrata dobivenoga ovim ispitivanjem dovelo je do povoljnih rezultata u smanjenju nekorisne komponente Fe2O3 (0,04 %) i povećanju korisne komponente Al2O3 . Nakon toga u ispitivanjima dizajniranim Taguchijevom metodom određen je utjecaj parametara kao što su vrijeme, temperatura procesa, koncentracija HCl i veličina zrna sirovine, na uklanjanje željeza iz boksita procesima luženja HCl. Prema dobivenim rezultatima najbolja učinkovitost uklanjanja željeza za veličinu ulaznoga zrna od 250 µm postiže se u sljedećim uvjetima: 30 % HCl, temperatura procesa od 25°C i vrijeme procesa 120 minuta. U ovome slučaju učinkovitost uklanjanja željeza i sadržaj Fe2O3 u procesnome koncentratu iznosi 92,78 % odnosno 0,56 %

Takotsubo cardiomyopathy associated with opiate withdrawal

DIT SCI 1105 Operating Syste