338 research outputs found

    A Gossip Algorithm based Clock Synchronization Scheme for Smart Grid Applications

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    The uprising interest in multi-agent based networked system, and the numerous number of applications in the distributed control of the smart grid leads us to address the problem of time synchronization in the smart grid. Utility companies look for new packet based time synchronization solutions with Global Positioning System (GPS) level accuracies beyond traditional packet methods such as Network Time Proto- col (NTP). However GPS based solutions have poor reception in indoor environments and dense urban canyons as well as GPS antenna installation might be costly. Some smart grid nodes such as Phasor Measurement Units (PMUs), fault detection, Wide Area Measurement Systems (WAMS) etc., requires synchronous accuracy as low as 1 ms. On the other hand, 1 sec accuracy is acceptable in management information domain. Acknowledging this, in this study, we introduce gossip algorithm based clock synchronization method among network entities from the decision control and communication point of view. Our method synchronizes clock within dense network with a bandwidth limited environment. Our technique has been tested in different kinds of network topologies- complete, star and random geometric network and demonstrated satisfactory performance

    A Spectrum Sharing based Metering Infrastructure for Smart Grid Utilizing LTE and WiFi

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    In advanced metering infrastructure (AMI) of smart grid, WiFi is an appropriate choice for its bidirectional communication requirement to transmit data to the billing center. But, WiFi functions in the free spectrum bands and LTE also requires to use the same free bands for its network expansion being licensed spectrum is limited and expansive. LTE and WiFi can operate simultaneously in the 3.5 GHz band (also known as citizen broadband radio service (CBRS)), which has large amount of free and clean spectrum. In this paper, we propose a smart grid metering infrastructure based on fixed duty cycled LTE and WiFi, where smart meters and its’ data collectors (known as Access Point) use WiFi and LTE, respectively, for transferring data. Under a system level simulation environment, we investigated the LTE-WiFi coexistence performance in CBRS band considering a time division duplexing (TDD)-LTE associated with FTP traffic, and IEEE 802.11n (WiFi). The simulation performance demonstrates a good neighborhood coexistence between WiFi and LTE, which makes it a potential communication solution for the AMI

    Online power quality disturbance detection by support vector machine in smart meter

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    Power quality assessment is an important performance measurement in smart grids. Utility companies are interested in power quality monitoring even in the low level distribution side such as smart meters. Addressing this issue, in this study, we propose segregation of the power disturbance from regular values using one-class support vector machine (OCSVM). To precisely detect the power disturbances of a voltage wave, some practical wavelet filters are applied. Considering the unlimited types of waveform abnormalities, OCSVM is picked as a semi-supervised machine learning algorithm which needs to be trained solely on a relatively large sample of normal data. This model is able to automatically detect the existence of any types of disturbances in real time, even unknown types which are not available in the training time. In the case of existence, the disturbances are further classified into different types such as sag, swell, transients and unbalanced. Being light weighted and fast, the proposed technique can be integrated into smart grid devices such as smart meter in order to perform a real-time disturbance monitoring. The continuous monitoring of power quality in smart meters will give helpful insight for quality power transmission and management

    Cycle-accurate modeling of multicore processors on FPGAs

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 169-176).We present a novel modeling methodology which enables the generation of a high-performance, cycle-accurate simulator from a cycle-level specification of the target design. We describe Arete, a full-system multicore processor simulator, developed using our modeling methodology. We provide details on Arete's resource-efficient and high-performance implementation on multiple FPGA platforms, and the architectural experiments performed using it. We present clear evidence that the use of simplified models in architectural studies can lead to wrong conclusions. Through two experiments performed using both cycle-accurate and simplified models, we show that on one hand there are substantial quantitative and qualitative differences in results, and on the other, the results match quite well.by Asif Imtiaz Khan.Ph.D

    Emulation of microprocessor memory systems using the RAMP design framework

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 49-50).With the computer hardware industry and the academic world focused on multiprocessor systems, the RAMP project is aiming to provide the infrastructure for supporting high-speed emulation of large scale, massively-parallel multiprocessor systems using FPGAs. The RAMP design framework provides the platform for building this infrastructure. This research utilizes this design framework to emulate various microprocessor memory systems through a model built in an FPGA. We model both the latency and the bandwidth of memory systems through a parameterized emulation platform, thereby, demonstrating the validity of the design framework. We also show the efficiency of the framework through an evaluation of the utilized FPGA resources.by Asif I. Khan.S.M

    Evaluating chickpea genotypes for abiotic stress tolerance

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    Being a leguminous crop chickpea (Cicer arietinum L.) is important for the establishment of sustainable and economically viable farming systems. Chickpea is grown and consumed across five continents, making this crop more important in international markets than other food legumes. Adaptation trials of 15 accessions of chickpea, 13 from the ICARDA collection and 2 from the Portuguese national catalogue, took place during two years in two different countries (Portugal, Syria). The trials were conducted under rainfed conditions using a late sowing date to naturally expose the plants to drought and heat stress. The accumulated results indicate a high variability in the yield response among genotypes and regions. In Portugal differences between the most productive accession and the least productive one was higher than 1000 kg/ha in 2009 (drought year) and than 1500Kg/ha in 2010 (rainy year). In general, genotypes that fasten their development cycle showed higher grain yield, especially in drought years. Comparing the two years, we observed three groups of genotypes: i) Stable genotypes, well adapted to distinct environments (like ILC588). ii) Genotypes adapted to adverse conditions, but not responding to favourable conditions (ICL 216); this genotype was also among the best performers under drought conditions in Syria. iii) Genotypes adapted to good conditions, but with bad performance under adverse conditions (ICL 3279). Across the two locations, Portugal and Syria, FLIP03-145C, FLIP87-8C and ILC 588 were on the top 5 during 2009. In 2010, only FLIP87-8C standout to be among the best performers under drought conditions in both countries

    Evaluation of the genetic structure of the urban dwelling species of Bank Myna (Acridotheres ginginisnus) using random amplified polymorphic DNA (RAPD) analysis

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    We used the random amplified polymorphic DNA (RAPD) technique to decipher the genetic structure of the Bank Myna (Acridotheres ginginisnus) in Pakistan. The samples were collected from four cities namely: Dera Ghazi Khan, Jahanian, Khanewal and Gujranwala. The analysis showed a high genetic diversity at species level (H = 0.318, S = 0.467) but low levels at population levels (H = 0.047, S = 0.069 to H = 0.195, S = 0.283). The four populations analyzed were genetically distant from each other and hinted the effect of urbanization role in isolating the urban dwelling species. The genetic distances between populations ranged from D = 0.2403 to D = 0.3419 and the similarity coefficient showed low range from 0.66 to 0.70. This study will help in future conservation plans and also help the understanding of the role of urbanization on fragmentation of species’ natural distribution and dispersal mechanism.Key words: Acridotheres ginginisnus, Bank Myna, random amplified polymorphic DNA (RAPD), genetic structure

    CBRS Spectrum Sharing between LTE-U and WiFi: A Multiarmed Bandit Approach

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    The surge of mobile devices such as smartphone and tablets requires additional capacity. To achieve ubiquitous and high data rate Internet connectivity, effective spectrum sharing and utilization of the wireless spectrum carry critical importance. In this paper, we consider the use of unlicensed LTE (LTE-U) technology in the 3.5 GHz Citizens Broadband Radio Service (CBRS) band and develop a multiarmed bandit (MAB) based spectrum sharing technique for a smooth coexistence with WiFi. In particular, we consider LTE-U to operate as a General Authorized Access (GAA) user; hereby MAB is used to adaptively optimize the transmission duty cycle of LTE-U transmissions. Additionally, we incorporate downlink power control which yields a high energy efficiency and interference suppression. Simulation results demonstrate a significant improvement in the aggregate capacity (approximately 33%) and cell-edge throughput of coexisting LTE-U and WiFi networks for different base station densities and user densities

    Prevalence of Muscle Dysmorphia and Associated Health Activities in Male Medical Students in Karachi, Pakistan

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    Background: Muscle Dysmorphia (MD) is a subtype of body dysmorphic disorder (BDD) and is currently classified under anxiety disorders (subheading: Obsessive-compulsive disorder) in DSM 5. MD is hypothesized to affect the self-esteem and social outlook of the younger generation. MD shows a higher rate in males and may influence their self-confidence rendering them more prone towards using steroids, supplementary proteins and other drugs to alter their physical outlooks as shown in previous studies. This problem has been on the rise lately due to revolutionary advancement in the media and film industry and the abrupt changes about the standards of physical good looks and body shapes. With the lack of studies done in our population, our study will be helpful to consider the prevalence of the disease in our setting and increase awareness in the general public and clinicians. We hope to help clinicians/ therapists find better options in managing the disease. Materials: We performed a cross-sectional study with a sample size of 246 medical school students in Karachi to collect data through self-administered questionnaires. We used the DSM 5 criteria for the diagnosis of BDD and additional questions on the presence of MD. Nutritional habits, exercise routines, use of supplements and drugs were also obtained for exploratory analysis. Results: Our study predicted the prevalence of MD to be 25%. Other main findings included statistical significant associations between MD and the thoughts and practice of steroid use for muscularity. Conclusion: MD is an underdiagnosed and often unrecognized disease that we believe has significant consequences for the young male population. Further work is needed on this in our part of the world. Our research, we believe, can be a stepping stone for further studies that would incorporate wider populations
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