Ultra-Low Voltage SRAM in 130nm CMOS Process

This thesis explores the viability of implementing a ultra-low voltage SRAM topology in a 130nm CMOS process for Atmel Norway AS. The topology supports voltage scaling between a subthreshold voltage of 400mV and a regular supply voltage of 1.2V. SRAM cells for ultra-low voltage operation and surrounding read and write circuitry is implemented using state of the art design techniques and literature.An asynchronous self-timed SRAM topology was implemented with conventional 6T SRAM cells and 10T SRAM cells specifically designed for ultra-low voltage operation. A small set of logic gates was also designed for ultra-low voltage operation to realize the surrounding read and write control circuitry. All building blocks were simulated with extracted parasitics from layout to get realistic simulation results. Corner and Monte Carlo simulations were used to show how temperature and process variations statistically affected the building blocks and their performance at both subthreshld and superthreshold voltages.Simulation results shows that the 10T cell is more robust at 400mV with a 60-70% larger static noise margin compared to the conventional 6T cell, but consumes more leakage power and is physically 64% larger. The 10T cell also needs more time to perform a read "0" operation since the single-ended nature of the SRAM cell requires a full bitline-swing to perform the read operation whereas the differential nature of the 6T cells speed up the read operation, but the offset voltage of the sense amplifier limits the speed gain at 400mV somewhat compared to at 1.2V. The read operation of the 6T cell causes a disturb voltage in the internal nodes of the SRAM cell and its magnitude is affected by the number of SRAM cells in the array, the width of the wordline signal and temperature. The impact of these factors are greater at high voltages, making it difficult to assess the yield in systems with voltage scaling. The 10T cell uses a read buffer to decouple the read and write operation and do not encounter this problem and this makes the 10T cell more predictable with voltage scaling and the safest choice for future implementations.The results also show that the power savings when moving from 1.2V to 400mV are withing the range of 5-18 times depending on the severity of process variations and temperature. The lowest power savings occur at high temperatures due to increased leakage currents. The largest savings occurs at low temperatures, but the performance is degraded to such a degree that the 10T implementation requires 5 32kHz clock cycles to complete a read "0" operation while the 6T implementation requires 3 at -40C in the SS process corner. To combat the extreme degradation in speed the supply voltage must be raised either permanently or through some kind of dynamic supply voltage compensation

Performance of cylindrical converters with preferred-crystal-orientation emitters of chemically vapor deposited tungsten

Design and evaluation of cylindrical out-of-pile thermionic converter test vehicle to determine performance of tungsten emitters with preferred crystal orientatio

Verdien av raskere og mer pålitelig godstransport

Vi konstruerer en logistikkostnadsmodell som inkluderer de ulike transport¬kostnads¬elementene, og avleder tidsverdier og pålitelighetsverdier av den med hjelp av omhyllingssetningen. Vi finner at tidsverdien består av de kilometer¬avhengige transportkostnadene pluss kostnaden ved å binde kapital i varer under transport. I tillegg finner vi en eksplisitt formel for verdsetting av økt pålitelighet. For å finne ut hvordan forventet transporttid og variansen til transporttida endrer seg med ulike tiltak, anvender vi en teoretisk modell for forventning og varians til forsinkelsen pr. kilometer som følge av hendelser på vegen. Dermed har vi – i teorien – et fullstendig opplegg for å beregne nytte for godstrafikken av tiltak som påvirker transporttidas forventning og varians. Det gjenstår å utvide opplegget til andre transportformer enn vegtransport, å vurdere andre kilder til forsinkelser enn hendelser undervegs, og å tilrettelegge data som trenges til opplegget

The role of the complement system in traumatic brain injury: a review

Traumatic brain injury (TBI) is an important cause of disability and mortality in the western world. While the initial injury sustained results in damage, it is the subsequent secondary cascade that is thought to be the significant determinant of subsequent outcomes. The changes associated with the secondary injury do not become irreversible until some time after the start of the cascade. This may present a window of opportunity for therapeutic interventions aiming to improve outcomes subsequent to TBI. A prominent contributor to the secondary injury is a multifaceted inflammatory reaction. The complement system plays a notable role in this inflammatory reaction; however, it has often been overlooked in the context of TBI secondary injury. The complement system has homeostatic functions in the uninjured central nervous system (CNS), playing a part in neurodevelopment as well as having protective functions in the fully developed CNS, including protection from infection and inflammation. In the context of CNS injury, it can have a number of deleterious effects, evidence for which primarily comes not only from animal models but also, to a lesser extent, from human post-mortem studies. In stark contrast to this, complement may also promote neurogenesis and plasticity subsequent to CNS injury. This review aims to explore the role of the complement system in TBI secondary injury, by examining evidence from both clinical and animal studies. We examine whether specific complement activation pathways play more prominent roles in TBI than others. We also explore the potential role of complement in post-TBI neuroprotection and CNS repair/regeneration. Finally, we highlight the therapeutic potential of targeting the complement system in the context of TBI and point out certain areas on which future research is needed

A simulation and machine learning approach to critical infrastructure resilience appraisal : Case study on payment disruptions

This study uses a simulation to gather data regarding a payment disruption. The simulation is part of a project called CCRAAAFFFTING, which examines what happens to a society when a payment disruption occurs. The purpose of this study is to develop a measure for resilience in the simulation and use machine learning to analyse the attributes in the simulation to see how they affect the resilience in the society. The resilience is defined as “the ability to bounce back to a previous state”, and the resilience measure is developed according to this definition. Two resilience measurements are defined, one which relates the simulated value to the best-case and worst-case scenarios, and the other which takes the pace of change in values into consideration. These two measurements are then combined to one measure of the total resilience. The three machine learning algorithms compared are Neural Network, Support Vector Machine and Random Forest, and the performance measure of these are the error rate. The results show that Random Forest performs significantly better than the other two algorithms, and that the most important attributes in the simulation are those concerning the customers’ ability to make purchases in the simulation. The developed resilience measure proves to respond logically to how the situation unfolded, and some suggestions to further improve the measurement is provided for future research.I denna studie används en simulering för att samla in data. Simuleringen är en del i ett projekt som kallas för CCRAAAFFFTING, vars syfte är att undersöka vad som händer i ett samhälle om en störning i betalsystemet inträffar. Syftet med denna studie är att utveckla ett mått för resiliens i simuleringen, samt att använda machine learning för att analysera attributen i simuleringen för att se hur de påverkar resiliensen i samhället. Resiliensen definieras enligt ”förmågan att snabbt gå tillbaka till ett tidigare stadie”, och resiliensmåttet utvecklas i enlighet med denna definition. Två resiliensmått definieras, där det ena måttet relaterar det simulerade värdet till de värsta och bästa scenarierna, och det andra måttet tar i beaktning hur snabbt värdena förändrades. Dessa två mått kombineras sedan till ett mått för den totala resiliensen. De tre machine learning-algoritmerna som jämförs är Neural Network, Support Vector Machine och Random Forest, och måttet för hur de presterar är felfrekvens. Resultaten visar att Random Forest presterar märkbart bättre än de andra två algoritmerna, och att de viktigaste attributen i simuleringen är de som berör kunders möjlighet att genomföra köp i simuleringen. Det utvecklade resiliensmåttet svarar på ett logiskt sätt enligt hur situationen utvecklar sig, och några förslag för att vidare utveckla måttet ges för vidare forskning

Tolking av aktiv udrenert skjærefasthet fra vingebor

Rapporten ser på muligheten for å etablere en korreksjonsfaktor for vingebor relatert til skjærefasthet fra aktiv treaksialforsøk basert på datasett med vingeborforsøk og aktive treaksialforsøk - i alt 137 datapunkter fra 21 lokasjoner. Det konkluderes med at det er mulig å etablere en slik korrelasjon som funksjon av plastisitetsindeks. Det anbefales videre å arbeide for å etablere et utvidet datagrunnlag av høy kvalitet i form av en vingebor/ blokkprøvedatabas

Värdering av kriterier vid stora investeringar : En jämförelse mellan olika intressenters uppskattningar av kriterier

In what way does different stakeholders assess a decision and its consequences, and how do these assessments differ? When a company stands before a big decision, they need to consider aspects that are economic, ecologic and social. To make a good decision they need to consider the society and its different stakeholder groups. This study examined how different groups values and weights different criteria. The study has been done with the project Sundsvall logistics park as a case, with criteria related to that project. The goal of the study was to find a way to value and weight different criteria and then compare how the company and the stakeholders assesses these criteria. This has been done through interviews with relevant people that has got extra knowledge about the project Sundsvall logistics park, and through a survey that has been sent out to residents of Sundsvall. The informants and respondents got to assess values and weights to the criteria relative to an indirect alternative where the logistics park isn’t built. The data was then compiled using multi attribute utility theory as a tool to present the comparison. The result of the study suggests that the differences between the valuations and weightings of the criteria is partly due to an uncertainty in how the logistics park would affect the criteria, but that the biggest reason probably depends on what perspective the person is viewing the logistics park from. If the person is viewing the logistics park from an industrial perspective, the criteria related to industrial development is getting more important and is going to take up more room in the analysis. If the person is viewing the logistics park from an individual and social perspective, the criteria related to that is more important and takes up more room in the analysis.På vilket sätt uppskattar olika intressenter ett beslut och dess konsekvenser, och hur skiljer sig dessa uppskattningar åt? När företag idag står inför stora beslut behöver de ta hänsyn till aspekter som är både ekonomiska, ekologiska och sociala. För att beslutet ska bli bra behöver de ta hänsyn till samhället och dess olika intressentgrupper. Denna studie är en undersökning av hur olika grupper värderar och viktar olika kriterier. Studien har utförts mot projektet Sundsvall Logistikpark med kriterier relaterade till projektet. Målet med studien har varit att hitta ett sätt att värdera och vikta olika kriterier för att sedan göra en jämförelse av hur företaget och intressenterna uppskattar dessa kriterier. För att göra detta har intervjuer utförts med personer som är extra insatta i projektet med Sundsvall logistikpark och en enkät skickats ut till boende i Sundsvall. Informanterna och respondenterna har fått uppskatta värden och vikter på kriterierna utifrån ett indirekt alternativ där logistikparken inte byggs. Datan har sedan sammanställts genom att använda multiattributsnyttoteori som verktyg för att presentera jämförelsen. Resultatet av undersökningen tyder på att de skillnader som finns i värderingar och viktningar av kriterierna dels beror på en viss osäkerhet angående hur logistikparken skulle kunna påverka de olika kriterierna och hur ett värde kan uppskattas på dessa, men att den största orsaken troligen beror på vilket perspektiv personen ser logistikparken på. Om personen ser på logistikparken från ett industriellt perspektiv blir kriterier som har med industriell utveckling att göra viktigare och tar större plats i analysen. Om personen ser på logistikparken från ett individuellt och socialt perspektiv blir sådana kriterier viktigare och tar större plats i analyse