Reducing dram access latency by exploiting dram leakage characteristics and common access patterns

DRAM tabanlı bellek, bilgisayar sisteminde darboğaz oluşturarak sistemin başarımı sınırlayan en önemli bileşendir. Bunun sebebi işlemcilerin hız bakımından DRAM'lerin çok önünde olmasıdır. Bu tezde, ChargeCache ismini verdiğimiz, DRAM'lerin erişim gecikmesini azaltan bir yöntem geliştirdik. Bu yöntem, piyasadaki DRAM yongalarının mimarisinde bir değişiklik gerektirmediği gibi, bellek denetimcisinde de düşük donanım maliyeti olan ek birimlere ihtiyaç duymaktadır. ChargeCache, yeni erişilmiş DRAM satırlarının kısa bir süre sonra tekrar erişileceği gözlemine dayanmaktadır. Yeni erişilmiş satırlardaki DRAM hücreleri yüksek miktarda yük içerdiğinden, bunlara hızlı bir şekilde erişilebilir. Bu gözlemden faydalanmak için yeni erişilen satırların adreslerini bellek denetimcisi içerisinde bir tabloda tutmayı öneriyoruz. Sonraki erişim isteklerinin bu tablodaki satırlara erişmek istemesi durumunda, bellek denetimcisi yük miktarı yüksek hücrelerin erişilmek üzere olduğunu bileceğinden, DRAM erişim değiştirgelerini ayarlayarak erişimin düşük gecikmeyle tamamlanmasını sağlayabilir. Belirli bir süre sonra tablodaki satır adresleri silinerek, zaman içerisinde çok fazla yük kaybedip hızlı erişilebilme özelliğini yitirmiş satırların bu tablodan çıkarılması sağlanır. Önerdiğimiz yöntemi hem tek çekirdekli hem de çok çekirdekli mimarilerde benzetim ortamında deneyerek, yöntemin başarım ve enerji kullanımı açısından sistem üzerinde sağladığı iyileştirmeleri inceledik.DRAM-based memory is a critical factor that creates a bottleneck on the system performance since the processor speed largely outperforms the DRAM latency. In this thesis, we develop a low-cost mechanism, called ChargeCache, which enables faster access to recently-accessed rows in DRAM, with no modifications to DRAM chips. Our mechanism is based on the key observation that a recently-accessed row has more charge and thus the following access to the same row can be performed faster. To exploit this observation, we propose to track the addresses of recently-accessed rows in a table in the memory controller. If a later DRAM request hits in that table, the memory controller uses lower timing parameters, leading to reduced DRAM latency. Row addresses are removed from the table after a specified duration to ensure rows that have leaked too much charge are not accessed with lower latency. We evaluate ChargeCache on a wide variety of workloads and show that it provides significant performance and energy benefits for both single-core and multi-core systems

Design and analysis of a hybrid timber-steel floating substructure for a 15 MW semisubmersible-type FWT

Wind energy has developed to be among the most promising sources of renewable energy. Furthermore, floating offshore wind turbines have presented the opportunity for higher power production in intermediate (45-150 m) and deep water (> 150 m). However, the manufacturing, installation, and operation of wind turbines in general, and floating wind turbines in particular, can result in significant amounts of greenhouse gas emissions (GHG). This thesis proposes a novel design of a hybrid timber-steel floating substructure for the IEA 15 MW floating wind turbine. The new design presents a modified version of the UMaine VolturnUS-S semisubmersible platform that was initially developed for the same turbine. The main objective of the new design is to reduce the turbine’s overall CO2 footprint. This objective is achieved by replacing structural steel with glued laminated timber, a more sustainable material known for its environmental benefits. Firstly, a robust design methodology is introduced. Secondly, Ansys workbench 2020 R1 is utilized to compare and then select between three preliminary hybrid timber-steel models based on a set of criteria that are extracted from relevant standards for both timber and steel. Compared to the UMaine VolturnUS-S semisubmersible platform, the selected hybrid configuration provides a considerable reduction in the steel mass (around 590 t). Subsequently, fully coupled aero-hydro-servo-elastic dynamic analysis is carried out using OpenFAST to validate the selected model. Only the ultimate limit state design (ULS) for the turbine under extreme and normal operating conditions is considered. The results from the numerical analysis show that the selected model fulfills all design criteria with a utilization factor that varies between 74- 94% for the different design load cases. In the end, the work concludes that the glulam-based supporting structure offers an effective load-bearing solution for the IEA 15 MW turbine, contributing to the development of floating wind energy with minimal cost and CO2 footprint. However, a series of tasks and suggestions are proposed to enhance the process of developing an optimal timber-steel design

Experimental taxonomy of oxalis section acetosellae and maianthemum

The taxonomy distribution of Maianthemum Web. (liliaceae) and Oxalis section Acetoaellae, are discussed withreference to their variation and evolution. I n Maianthemum there are two main taxai M. dilatatum (Wood) Nels. & Macbr., confined to the Pacific region? and M.bifolitun (L.) Schmidt with a wider distribution. The latter consists of three subspecies, subspecies bifolium of Eurasia, and subspecies canadense and subspecies interius of N. America. All these have some populations or Individuals with 2n = 36, but all also have representatives with higher chromosome numbers, 2n = 54 or 2n = c72. It is not yet possible to evaluate the chromosome races taxonomically. The taxa have similar karyotypes; the chromosomes are rather large and some are satellited. The evidence suggests that the plants with 2n = 54 and 72 are autopolyploids based on 2n = 36. Hybridization experiments have produced good seeds and a few seedlings, but no hybrids have been raised to maturity; the experiments support the view of a close genetic relationship between the taxa. M.dilatatum is morphologically variable. In Asia it has been modified as a result of contact with M.bifolium;hybridization and introgression between them may have resulted in a recognised Asian variety. In Oxalis, little is known about the Asiatic taxa. Of the other northern hemisphere taxa O.acetosella L. of Eurasia and O.montana Raf. of N. America are best treated as subspecies of O.acetosella. Hybridization experiments, because of germination difficulties, have been inconclusive. O.oregana Butt, of northwest America, is distinct from O.acetosella and hybridization experiments gave empty seeds. All three taxa have similar karyotypes. Problems of phytogeography are discussed. In both genera the taxa along the Pacific coasts of N. America are different from those of C. and E.N. America, a possible indication of their early isolation from the main stock, which perhaps originated in E. Asia

The use and safety of oral anticoagulants in patients with type 2 diabetes mellitus in the UK

Type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVDs) often coexist. Oral anticoagulants (OACs) are prescribed for the management of CVDs. However, the safety of OACs in T2DM patients remains unclear. This PhD research aimed to evaluate the use and safety of OACs in T2DM patients. The Health Improvement Network primary care database of the United Kingdom was used to achieve the project aims. Firstly, a systematic review and meta-analysis were conducted to review the literature. Secondly, a drug utilisation study was conducted to evaluate the prescribing of OACs in T2DM. Then, two studies were conducted to explore the epidemiology and treatment of AF in T2DM. Finally, an analytical cohort study using the propensity score and Cox regression models was conducted to investigate the safety of the use of OACs and oral hypoglycaemic agents (OHAs) in T2DM. The pooled average of the prevalence of hypoglycaemia in diabetes was 11.0% (95% confidence intervals, 7.0% – 17.0%). The prevalence of OACs prescribing increased by 50.8% from 4.4% (4.2% – 4.6%) in 2001 to 6.6% (6.5% – 6.7%) in 2015. The prevalence of AF increased from 2.7% (2.5% – 2.8%) in 2001 to 5.0% (4.9% – 5.1%) in 2016. T2DM patients with AF, aged 60-79, males, and BMI ≥25, were more likely to receive OAC. The cohort study results showed that compared with sulfonylurea only, concurrent use of warfarin and sulfonylureas, increased the risk of hypoglycaemia and bleeding, (HR 1.38, (1.10 – 1.75)), (HR 1.12, (1.01 – 1.24)), respectively. However, there was no association between the use of DOACs and sulfonylureas concurrently and the risk of hypoglycaemia, (HR 0.54, (0.27 – 1.10)). In conclusion, the prevalence of AF and the use of OACs in T2DM patients have increased over the last decade. T2DM patients are at a higher risk of developing serious adverse events when warfarin and sulfonylureas are used concurrently

Calix[4]pyrrole macrocycle: Extraction of fluoride anions from aqueous media

Solid-phase extraction of fluoride anions by calixpyrrole macrocycle (CP) from aqueous media has been studied using the batch method. Various significant extraction parameters like initial concentration of the anion, extraction time, concentration of the calixpyrrole, pH and temperature were evaluated. Langmuir, Freundlichand, Dubinin-Redushkevish (D-R) isotherms and coefficients were used to analyze the equilibrium data. The amount of fluoride anion extracted per unit of the CP was found to be 0.40 mg/g at 298 K from 19 mg/L aqueous solution of fluoride anions. The mean free energy calculated from D-R model for the removal of fluoride anions by the CP was found to be 10.0 kJ/mol, indicating that chemisorption is involved in the extraction process. The data were also fitted to kinetic models such as pseudo first order and pseudo second order. The removal of fluoride anions increased with increasing temperature indicating the endothermic nature of the extraction process. The present method has been compared with the previous methods

Algunos caracteres analíticos de variedades de semillas de algodón cultivadas en Turquía

Sixteen cottonseed varieties grown in Turkey were analysed. The average oil content in varieties ranged from 309.7g Kg-1 to 379.5g Kg-1 whereas the range in values of gossypol content for glanded varieties was 7.4-12.8g Kg-1. One glandless variety contained gossypol as 0.2g Kg-1. The samples contained 337.2- 466.5g Kg-1 protein. Fatty acid composition of the oils obtained from cottonseed varieties were also determined. Generally total gossypol content of cottonseed varieties were below the limits established by the some nations for human food or animal feed.Se han analizado dieciséis variedades de semillas de algodón cultivadas en Turquía. El contenido medio de aceite en las distintas variedades osciló entre 309,7g Kg-1 y 379,5g Kg-1 mientras que el contenido en gosipol para variedades con glándulas fue desde 7,4 a 12,8g Kg-1. Una variedad sin glándula tuvo un valor en gosipol de 0, Kg-1. El valor en proteínas de las muestras osciló entre 337,2 y 466,5g Kg-1. También se determinó la composición en ácidos grasos de los aceites obtenidos de las distintas variedades de semilla de algodón. Por lo general el contenido total en gosipol en las distintas variedades fue inferior a los límites establecidos por algunas naciones para su consumo humano o para alimentación animal

Population Growth and its Spatial Dimension and its Impact on the Sustainable Standard of Residential land Uses. Najaf District Case Study for the Period 2020-2025

هناك تأثيراً للنمو السكاني على استعمالات الأرض الحضرية, ولابد من الاستعداد والتنبأ بالنتائج الممكنة او المحتملة, وما تسببه من مشاكل من جراء سوء التخطيط والإدارة  والتنفيذ, ناهيك عن التهاون في حساب التنبؤ باتجاه وحجم العلاقة بين النمو السكاني والنمو العمراني, وعلى وجه الخصوص التشبع والتنوع العمراني المحتمل بفعل وتأثير النمو السكاني, ولكي لا ننتظر حدوث المشكلة, علينا أن نبادر ونعترف أن هناك مشكلة محلية وإقليمية في موضوع الإسكان ونمو السكان, أي أن الرصيد السكني  لا يلبي الحاجة السكنية بسبب النمو السكاني المتزايد مما يخلق فجوة متزايدة بينهما, اعتمد البحث المنهج التحليلي الوصفي لبيانات تاريخية حقيقية لكل من سكان ومساحات الأحياء السكنية والحصة المعيارية المستدامة للاستعمال السكني لقضاء النجف, الذي قُسم إلى ستة نطاقات؛ وذلك ليسهل علينا دراستها وتحليل متغيراتها, والتنبؤ بالمعيار المستدام المتنامي للمناطق السكنية لخمس سنوات قادمة في منطقة الدراسة, ومن بين النتائج الأهم أن هناك سوء تدبير وتقدير للنمو السكاني الذي ولد تشبع عمراني في استعمالات الأرض الحضرية, وفي مقدمتها تفاوت التأثير للنمو السكاني على المعيار السكني المستدام, وهذا بطبيعة الحال أنتج نسبة معيارية مستدامة لائقة ومقبولة للاستعمال السكني, و نسبة معيارية غير مستدامة وغير لائقة وغير مقبولة للاستعمال السكني, وكلاهما يقعان بين الحدّ الأعلى والأدنى للمعيار وأحيانا خارج الحدّ الأعلى. وللحفاظ على استدامة المعيار المتنامي، لينسجم مع واقع استعمالات الأرض الحضرية بات لزاما تحريك او نقل المتنامي من السكان ضمن أو خارج النطاق (Zone)، وذلك لخلق انسجام مستدام بين السكان والإسكان في ظل معيار متنامي ومستدام.There is an impact of population growth on urban land uses, and it is necessary to prepare and predict the possible or potential results, and the problems it causes as a result of poor planning, management and implementation, not to mention the negligence in calculating the direction and size of the relationship between population growth and urban growth, in particular urban saturation and diversity. The potential effect of population growth, and in order not to wait for the problem to occur, we must take the initiative and recognize that there is a local and regional problem in the issue of housing and population growth, meaning that the housing stock does not meet the housing need due to the increasing population growth, which creates an increasing gap between them. The research adopted a descriptive analytical approach to real historical data for both residents and residential areas and the sustainable standard share of residential use for Najaf district. Which was divided into six zones to make it easier for us to study them, analyze their variables, and predict the growing sustainable standard of residential areas for the next five years in the study area. One of the most important results is that there is a mismanagement and wrong estimation of population growth that has generated urban saturation in urban land uses. Foremost among them is the varying impact of population growth on the sustainable housing standard, which, of course, has created a decent and acceptable sustainable standard ratio for residential use and another that is unsustainable, inappropriate and unacceptable for residential use, both of them are located between the upper and lower limits of the standard and sometimes out of  standards. In order to maintain the sustainability of the growing standard to conform the reality of urban land uses, it is necessary to move or relocate the developing population within or outside zone to create sustainable harmony between population and housing under a growing and sustainable standard.&nbsp