Optimal Power Cost Management Using Stored Energy in Data Centers

Since the electricity bill of a data center constitutes a significant portion of its overall operational costs, reducing this has become important. We investigate cost reduction opportunities that arise by the use of uninterrupted power supply (UPS) units as energy storage devices. This represents a deviation from the usual use of these devices as mere transitional fail-over mechanisms between utility and captive sources such as diesel generators. We consider the problem of opportunistically using these devices to reduce the time average electric utility bill in a data center. Using the technique of Lyapunov optimization, we develop an online control algorithm that can optimally exploit these devices to minimize the time average cost. This algorithm operates without any knowledge of the statistics of the workload or electricity cost processes, making it attractive in the presence of workload and pricing uncertainties. An interesting feature of our algorithm is that its deviation from optimality reduces as the storage capacity is increased. Our work opens up a new area in data center power management.Comment: Full version of Sigmetrics 2011 pape

LAPSES: A Recipe for High-Performance Adaptive Router Design

Earlier research has shown that adaptive routing can help in improving network performance. However, it has not received adequate attention in commercial routers mainly due to the additional hardware complexity, and the perceived cost and performance degradation that may result from this complexity. These concerns can be mitigated if one can design a cost-effective router that can support adaptive routing. This paper proposes a three step recipe — Look-Ahead routing, intelligent Path Selection, and an Economic Storage implementation, called the LAPSES approach — for cost-effective high performance pipelined adaptive router design. The first step, look-ahead routing, reduces a pipeline stage in the router by making table lookup and arbitration concurrent. Next, three new traffic-sensitive path selection heuristics (LRU, LFU and MAX-CREDIT) are proposed to select one of the available alternate paths. Finally, two techniques for reducing routing table size of the adaptive router are presented. These are called meta-table routing and economical storage. The proposed economical storage needs a routing table with only 9 and 27 entries for two and three dimensional meshes, respectively. All these design ideas are evaluated on a (16 16) mesh network via simulation. A fully adaptive algorithm and various traffic patterns are used to examine the performance benefits. Performance results show that the look-ahead design as well as the path selection heuristics boost network performance, while the economical storage approach turns out to be an ideal choice in comparison to full-table and meta-table options. We believe the router resulting from these three design enhancements can make adaptive routing a viable choice for interconnects.

To Move or Not To Move: The Economics of Cloud Computing

Abstract Cloud-based hosting promises cost advantages over conventional in-house (on-premise) application deployment. One important question when considering a move to the cloud is whether it makes sense for 'my' application to migrate to the cloud. This question is challenging to answer due to following reasons. Although many potential benefits of migrating to the cloud can be enumerated, some benefits may not apply to my application. Also, there can be multiple ways in which an application might make use of the facilities offered by cloud providers. Answering these questions requires an in-depth understanding of the cost implications of all the possible choices specific to 'my' circumstances. In this study We identify an initial set of key factors affecting the costs of a deployement choice. Using benchmarks representing two different applications (TPC-W and TPC-E) we investigate the evolution of costs for different deployment choices. We show that application characteristics such as workload intensity, growth rate, storage capacity and software licensing costs produce complex combined effect on overall costs. We also discuss issues regarding workload variance and horizontal partitioning

'e’-thinking teaching and assessment to uphold academic integrity: lessons learned from emergency distance learning

Covid-19 pandemic had an impact on many day-to-day activities but one of the biggest collateral impacts was felt by the education sector. The nature and the complexity of higher education is such that no matter how prepared we are as faculty, how planned our teaching and assessments, faculty are all too aware of the adjustments that have to be made to course plans, assessments designed, content delivery strategies and so on once classes begin. Faculties find themselves changing, modifying and deviating from original plans to ensure accessibility and inclusiveness, this may be due to a variety of reasons such as student abilities, behaviour, disturbances and even outside factors that may be political, environmental, social etc. Majority of the time, faculty are prepared for the change that needs to be incorporated and are quick to adjust. However, no one expected the disruption to education that was caused by COVID19 pandemic. The world came to a standstill while schools and universities scrambled to push learning to the digital space. It was important to try to ensure continuity of learning for students, but the issue of integrity came to the forefront by summertime. Faculties were suddenly expected to restructure their lessons, delivery, teaching and assessing digitally, at the same time ensuring and upholding integrity of the concepts taught and assessed. This has neither been easy or straightforward because the situation was unprecedented with little or no prior documentation or guidelines to help. Recognising this gap, this paper is an attempt at providing exploratory findings from authors’ experiences in their respective institutions over the ensuing months. The paper attempts to record the changes made by the faculty and colleagues to lessons and assessments with particular focus on how technology has been used to help restructure classes, deliver lessons and assess students which have aided in minimizing the likelihood of students cheating. The paper further narrates the reflective changes that were made in response to experience, student/external examiners feedback etc.N/

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

A framework for evaluating architectural issues of parallel systems

Ph.D.Umakishore Ramachandra