Toward sustainable data centers: a comprehensive energy management strategy

Data centers are major contributors to the emission of carbon dioxide to the atmosphere, and this contribution is expected to increase in the following years. This has encouraged the development of techniques to reduce the energy consumption and the environmental footprint of data centers. Whereas some of these techniques have succeeded to reduce the energy consumption of the hardware equipment of data centers (including IT, cooling, and power supply systems), we claim that sustainable data centers will be only possible if the problem is faced by means of a holistic approach that includes not only the aforementioned techniques but also intelligent and unifying solutions that enable a synergistic and energy-aware management of data centers. In this paper, we propose a comprehensive strategy to reduce the carbon footprint of data centers that uses the energy as a driver of their management procedures. In addition, we present a holistic management architecture for sustainable data centers that implements the aforementioned strategy, and we propose design guidelines to accomplish each step of the proposed strategy, referring to related achievements and enumerating the main challenges that must be still solved.Peer ReviewedPostprint (author's final draft

Robust Beamforming for Security in MIMO Wiretap Channels with Imperfect CSI

In this paper, we investigate methods for reducing the likelihood that a message transmitted between two multiantenna nodes is intercepted by an undetected eavesdropper. In particular, we focus on the judicious transmission of artificial interference to mask the desired signal at the time it is broadcast. Unlike previous work that assumes some prior knowledge of the eavesdropper's channel and focuses on maximizing secrecy capacity, we consider the case where no information regarding the eavesdropper is available, and we use signal-to-interference-plus-noise-ratio (SINR) as our performance metric. Specifically, we focus on the problem of maximizing the amount of power available to broadcast a jamming signal intended to hide the desired signal from a potential eavesdropper, while maintaining a prespecified SINR at the desired receiver. The jamming signal is designed to be orthogonal to the information signal when it reaches the desired receiver, assuming both the receiver and the eavesdropper employ optimal beamformers and possess exact channel state information (CSI). In practice, the assumption of perfect CSI at the transmitter is often difficult to justify. Therefore, we also study the resulting performance degradation due to the presence of imperfect CSI, and we present robust beamforming schemes that recover a large fraction of the performance in the perfect CSI case. Numerical simulations verify our analytical performance predictions, and illustrate the benefit of the robust beamforming schemes.Comment: 10 pages, 5 figures; to appear, IEEE Transactions on Signal Processing, 201

Green Cellular Networks: A Survey, Some Research Issues and Challenges

Energy efficiency in cellular networks is a growing concern for cellular operators to not only maintain profitability, but also to reduce the overall environment effects. This emerging trend of achieving energy efficiency in cellular networks is motivating the standardization authorities and network operators to continuously explore future technologies in order to bring improvements in the entire network infrastructure. In this article, we present a brief survey of methods to improve the power efficiency of cellular networks, explore some research issues and challenges and suggest some techniques to enable an energy efficient or "green" cellular network. Since base stations consume a maximum portion of the total energy used in a cellular system, we will first provide a comprehensive survey on techniques to obtain energy savings in base stations. Next, we discuss how heterogeneous network deployment based on micro, pico and femto-cells can be used to achieve this goal. Since cognitive radio and cooperative relaying are undisputed future technologies in this regard, we propose a research vision to make these technologies more energy efficient. Lastly, we explore some broader perspectives in realizing a "green" cellular network technologyComment: 16 pages, 5 figures, 2 table

A Study Report On Infant Feeding Practices In The Context Of\ud HIV / AIDS

\ud \ud This report presents the findings of a study on infant feeding practices in the context of HIV/AIDS in Tanzania. The study was undertaken from 8th – 24th August 2004 in 3 regions implementing PMTCT activities namely Kagera, Mbeya and Kilimanjaro. In each region, two PMTCT and one Non-PMTCT implementing districts were involved. The study population included mothers of infants who are HIV negative, infected and those of unknown status. Others were health service providers dealing with mothers and children, men and women of reproductive age and key informants. A total of 471 and 95 mothers with their infants were interviewed in PMTCT and Non-PMTCT sites respectively. Also 211 health service providers and 16 key informants were interviewed. HIV positive and negative mothers were selected purposively whereas those of unknown status were selected randomly. The quantitative data from mothers and health workers were collected by using structured questionnaires. A checklist was used to collect qualitative data from key informants such as TBAs, CBOs, FBOs, VHWs and VGLs. Another checklist was also used for facilitation of focus group discussion which involved men and women of reproductive age. In addition, secondary data from various sources were collected. The collected data were edited manually before being captured using excel, cleaned and finally transferred into SPSS version 10 for analysis. The results show that mean age of the interviewed mothers was 25 years and 62.4% of them had more than one child. Most mothers (87.3%) were married and (76.7%) were primary school leavers. There were 40% housewives. Proportion of mothers who delivered at health facility was 76.6%. Many of health service providers interviewed were Nurse Midwives, (45.5%) and nursing officers (21.3%). As regard to knowledge about breastfeeding, 50% of mothers were able to recognize its nutritional role and 34% knew the importance of colostrums. About breastfeeding initiation, 67.5 percent of mothers reported that it is recommended to start within an hour after delivery. However, a small proportion of mothers (2.5%) and (2.7%) appreciated the advantage of exclusive breastfeeding in relation to family planning and reducing the risk of MTCT of HIV respectively. Furthermore, 34.5% of mothers mentioned appropriate age for complementation as 4-6 months, where as 32.0% mentioned at 6 months. On the other hand, 24.6% of mothers reported to complement their infants at the age below 4 months. Complementary food given were named as maize porridge (40%), Lishe porridge 2.5% and cow’s milk 24%. Findings also show that frequency of feedingfor infants aged 6-9 months as mentioned by 39.8% of mothers was 3 times. However, there were 31.3% mothers who fed their infants 1-2 times a day. With regard to infant aged 10-12 months, the data show that 29.9% and 26.3 percent are fed 3 and 4 times a day respectively. Moreover, 6.0 percent of mothers did not know feeding frequency for infants aged 6-9 months and 9.2% of them were not aware of feeding frequency of infants aged 10-12 months. As regards to knowledge of mothers on MTCT of HIV, most of the mothers (over 90%), were aware that there is a possibility of MTCT of HIV. The awareness was high (over 90%) among the HIB +ve and HIV-ve mothers within the PMTCT sites. The risk was equally known by majority of mothers even in non-PMTCT sites. The findings also show that 57% of mothers that the commonest mode of MTCT of HIV is through breastfeeding. Generally in both PMTCT and non PMTCT sites MTCT of HIV through breastfeeding was the way known by many mothers. Among the mentioned factors that increase the risk of MTCT of HIV were breastfeeding exposure (35.2%), and breast conditions (25.1%). Other factors were sharing clothes between infant and mother; mothers’ spits and sweat on the breast during breast-feeding. However, re-infection with HIV and poor breastfeeding technique were less known as they were mentioned factors by 0.3 and 3.6 percent of mothers respectively. Ways of reducing MTCT of HIV as mentioned by mothers were replacement feeding (62.3%) and avoiding the infants to suckle on a breast with some spits and sweat (16.6%). On the other hand 3.2% of mothers were not aware about any way of reducing MTCT of HIV. However, 1.7 percent and 3.6 percent knew that EBF and ARV respectively could reduce the risk. In PMTCT sites both HIV infected (69%) and non infected (89%) mothers breastfed their infants soon after delivery. HIV positive mothers who reported to give their infants replacement feed soon after delivery were only 4.8%. The proportion of infants fed on breast milk after delivery was as high 81.1% even among mothers with unknown status. On top of that the findings also show that health service providers are the important source of information on infant feeding to mothers. They are depended by almost 70% of mothers and their influence as reported by mothers is very high (60.6%). Family members were also mentioned as other source of information. The main constraints as regard to infant feeding as reported by HIV infected mothers were the refusal of infants to eat other foods, insufficient breast milk and women heavy workload. However, majority of them (71.7%) did not report way constraint. In additional, the findings revealed that infant feeding counseling was given to majority (76.1%) of HIV infected mothers and only few (24.9%) of HIV negative women. About49.6% of HIV infected women were counseled on infant feeding option during pregnancy. Those counseled during and after delivery were 21.8% and 28.6% respectively. The most preferred infant feeding option was early cessation of breast feeding, as it was used by 55.7% of HIV positive women. Other women (17.1 and 14.3%) used exclusive breastfeeding for six months and commercial infant formula respectively. Affordability of infant feeding option was the main motivation (22.9%) to choose and use the said option, as compared to HIV transmission risk reduction (11.0%). Majority of HIV infected mothers (58.7%) reported to face no constraint as regard to implementation of infant feeding option. However, some of them (12%) mentioned stigma from family and community members as a major constraint to successful implementation of infant feeding option of their choice. Some health service providers (26.5%) mentioned the 4-6 months duration of exclusive breastfeeding and 46.4% mentioned the WHO / UNICEF recommended duration of 6 months. Furthermore, 13% of HSP were unable to demonstrate proper positioning and attachment of a baby on the breast, and 0.9% were not ware of the appropriate age for complementation. The findings further show that Few HSP in PMTCT (23%) were aware that there is a possibility of MTCT of HIV during pregnancy. On top of that there were (32.9%) of HSP in PMTCT aware of the increased risk of MTCT of HIV were due to breast conditions, only (4%) of HSP recognized the risk of MTCT associated with poor positioning and attachment of baby on breast. Furthermore, 44% of HSP in PMTCT sites were trained on infant feeding in the context of HIV/AIDS. With regards to infant feeding options 21.3% of The HSP in PMTCT sites mentioned exclusive breastfeeding for 6 months 29.5% mentioned early cessation of breastfeeding. Home prepared infant formula 20.7% and commercial infant formula was given by 15%. According to HSP in PMTCT sites, the main constraints faced by HIV infected mothers when implementing IFO are stigma (51.1%), avoiding to be known by other family members that they are HIV positive (20%), and switching from one option to another without consultation (22%). Overall, the study findings show that there is limitation in terms of knowledge and skills on breastfeeding, complementation and infant feeding options among HSP and mothers. More training, sensitization and media campaigns on infant feeding are needed. Counseling services on infant feeding option need to be strengthened. Also more research need to be conducted to explore the risk of MTCT transmission of HIV through the various existing mode of infant feeding among HIV infected mothers.\u

Scenarios for the development of smart grids in the UK: literature review

Smart grids are expected to play a central role in any transition to a low-carbon energy future, and much research is currently underway on practically every area of smart grids. However, it is evident that even basic aspects such as theoretical and operational definitions, are yet to be agreed upon and be clearly defined. Some aspects (efficient management of supply, including intermittent supply, two-way communication between the producer and user of electricity, use of IT technology to respond to and manage demand, and ensuring safe and secure electricity distribution) are more commonly accepted than others (such as smart meters) in defining what comprises a smart grid. It is clear that smart grid developments enjoy political and financial support both at UK and EU levels, and from the majority of related industries. The reasons for this vary and include the hope that smart grids will facilitate the achievement of carbon reduction targets, create new employment opportunities, and reduce costs relevant to energy generation (fewer power stations) and distribution (fewer losses and better stability). However, smart grid development depends on additional factors, beyond the energy industry. These relate to issues of public acceptability of relevant technologies and associated risks (e.g. data safety, privacy, cyber security), pricing, competition, and regulation; implying the involvement of a wide range of players such as the industry, regulators and consumers. The above constitute a complex set of variables and actors, and interactions between them. In order to best explore ways of possible deployment of smart grids, the use of scenarios is most adequate, as they can incorporate several parameters and variables into a coherent storyline. Scenarios have been previously used in the context of smart grids, but have traditionally focused on factors such as economic growth or policy evolution. Important additional socio-technical aspects of smart grids emerge from the literature review in this report and therefore need to be incorporated in our scenarios. These can be grouped into four (interlinked) main categories: supply side aspects, demand side aspects, policy and regulation, and technical aspects.

Handbook on Climate Change and Disaster Resilient Water, Sanitation and Hygiene Practices

This handbook was developed to help governmental and non-governmental agencies involved in safe water delivery, sanitation hygiene at local level, union and ward disaster management committees, to enhance their respective capacities to cope with climate change and disaster risks. It considers the rural context of Bangladesh and provides field-level workers and practitioners practical ideas about water supply, sanitation and hygiene practices in the context of climate change and disaster risk