371 research outputs found

    Sensing motion using spectral and spatial analysis of WLAN RSSI

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    In this paper we present how motion sensing can be obtained just by observing the WLAN radio signal strength and its fluctuations. The temporal, spectral and spatial characteristics of WLAN signal are analyzed. Our analysis confirms our claim that ’signal strength from access points appear to jump around more vigorously when the device is moving compared to when it is still and the number of detectable access points vary considerably while the user is on the move’. Using this observation, we present a novel motion detection algorithm, Spectrally Spread Motion Detection (SpecSMD) based on the spectral analysis of WLAN signal’s RSSI. To benchmark the proposed algorithm, we used Spatially Spread Motion Detection (SpatSMD), which is inspired by the recent work of Sohn et al. Both algorithms were evaluated by carrying out extensive measurements in a diverse set of conditions (indoors in different buildings and outdoors - city center, parking lot, university campus etc.,) and tested against the same data sets. The 94% average classification accuracy of the proposed SpecSMD is outperforming the accuracy of SpatSMD (accuracy 87%). The motion detection algorithms presented in this paper provide ubiquitous methods for deriving the state of the user. The algorithms can be implemented and run on a commodity device with WLAN capability without the need of any additional hardware support

    Using time-of-flight for WLAN localization: feasibility study

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    Although signal strength based techniques are widely employed for WLAN localization, they generally suffer from providing highly accurate location information. In this paper, we first present the general shortcomings of the signal strength based approaches used for WLANbased localization and then state reasons why time-of-flight could be an attractive alternative. We subsequently analyze the feasibility of using time-of-flight technique for WLAN localization by synchronizing the clock using Network Time Protocol (NTP) as well as measuring the time at (i) network layer level, (ii) data link layer level, and (iii) firmware level. We conclude that at present using TOF is not a feasible approach because of the limitation of current hardware and protocols

    Systematic mapping review on student’s performance analysis using big data predictive model

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    This paper classify the various existing predicting models that are used for monitoring andimproving students’ performance at schools and higher learning institutions. It analyses all theareas within the educational data mining methodology. Two databases were chosen for thisstudy and a systematic mapping study was performed. Due to the very infant stage of thisresearch area, only 114 articles published from 2012 till 2016 were identified. Within this, atotal of 59 articles were reviewed and classified. There is an increased interest and research inthe area of educational data mining, particularly in improving students’ performance withvarious predictive and prescriptive models. Most of the models are devised for pedagogicalimprovements ultimately. It is a huge scarcity in producing portable predictive models that fitsinto any educational environment. There is more research needed in the educational big data.Keywords: predictive analysis; student’s performance; big data; big data analytics; datamining; systematic mapping study

    Stochastic Budget Optimization in Internet Advertising

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    Internet advertising is a sophisticated game in which the many advertisers "play" to optimize their return on investment. There are many "targets" for the advertisements, and each "target" has a collection of games with a potentially different set of players involved. In this paper, we study the problem of how advertisers allocate their budget across these "targets". In particular, we focus on formulating their best response strategy as an optimization problem. Advertisers have a set of keywords ("targets") and some stochastic information about the future, namely a probability distribution over scenarios of cost vs click combinations. This summarizes the potential states of the world assuming that the strategies of other players are fixed. Then, the best response can be abstracted as stochastic budget optimization problems to figure out how to spread a given budget across these keywords to maximize the expected number of clicks. We present the first known non-trivial poly-logarithmic approximation for these problems as well as the first known hardness results of getting better than logarithmic approximation ratios in the various parameters involved. We also identify several special cases of these problems of practical interest, such as with fixed number of scenarios or with polynomial-sized parameters related to cost, which are solvable either in polynomial time or with improved approximation ratios. Stochastic budget optimization with scenarios has sophisticated technical structure. Our approximation and hardness results come from relating these problems to a special type of (0/1, bipartite) quadratic programs inherent in them. Our research answers some open problems raised by the authors in (Stochastic Models for Budget Optimization in Search-Based Advertising, Algorithmica, 58 (4), 1022-1044, 2010).Comment: FINAL versio

    Regeneration of plantlets from nodal and shoot tip explants of Anoectochilus elatus Lindley, an endangered terrestrial orchid

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    Anoectochilus elatus Lindley is an endangered terrestrial orchid. A procedure for the regeneration of complete plantlets of A. elatus Lindley through node and shoot tip explants resulted directly in shoots when cultured on a full strength Murashige and Skoog (1962) medium supplemented with cytokinins at different concentrations. An average number of shoots per explant is 3 in shoot tip and 4 in node, respectively. The best shoot proliferation was observed in 3.0 mg/l 1-phenyl-3-(1,2,3-thiadiazol-5-yl)-urea (TDZ) and the mean shoot length in 3.5 mg/l 6-furfurylaminopurine (KIN) (node) and 0.01 mg/l (shoot tip). Hundred percent rooting was achieved with the regenerated shoots in the same medium with the addition of 0.3 g/l activated charcoal (AC). Plantlets with well developed leaves and roots were transplanted to pots filled with a mixture of coconut coir, activated charcoal, commercial fertilizers (3:1:1) and acclimatized before been transferred to the greenhouse.Keywords: : Anoectochilus elatus, activated charcoal, regeneration, rootingAfrican Journal of Biotechnology Vol. 11(29), pp. 7549-7553, 10 April, 201

    In vitro propagation of Ceropegia thwaitesii Hook- an endemic species of Western Ghats of Tamil Nadu, India

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    In vitro propagation of Ceropegia thwaitesii Hook (Asclepiadaceae), an endemic plant species of Western Ghats, Tamil Nadu (India), was carried out. Auxiliary bud explants were cultured on Murashige and Skoog (MS) medium fortified with cytokinins (KIN), 6-benzyl adenine (BA), 2-isopentenyladenine (2-iP) and thidiazuron (TDZ) in various concentrations and in combination with auxins indole-3-butyric acid (IBA), indole-3-acetic acid (IAA) and naphthalene acetic acid (NAA). High frequency of shoot bud proliferation and multiplication was observed on KIN (13.94 ÎŒm) + IAA (28.54 ÎŒm). Rhizogenesis was observed on MS medium supplemented with IBA 2.46 ÎŒm and plantlets produced through micropropagation were hardened with the survival success of 73.33%. The efficient Micropropagation regeneration protocol developed would aid ex situ conservation of this endemic species.Key words: Ceropegia thwaitesii, in vitro propagation, Asclepiadaceae, plant growth regulators, micropropagation

    Management of coriander wilt using biocontrol agents

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    A replicated field trial on biocontrol of coriander wilt caused by Fusarium oxysporum f., sp. coriander; was conducted in kharif season during 1995-96, 1996-97 and 1997-98 in the Department of Spices and Plantation Crops, Horticultural College and Research Institute, TNAU, Coimbatore. Seed treatment with Trichoderma viride at 4 g kg-1 of seed was found to be more effective in reducing the wilt incidence to 5.3 per cent as against 28.3 per cent recorded in untreated, control plots in all the three years. The mean yield (387.5 kg ha-1) for all the three years was also significantly higher in seed treatment with T. viride as against very low yield (162 kg ha-1) obtained in untreated plots. The cost benefit ratio was also enhanced with the same treatment. &nbsp

    Haren: A Framework for Ad-Hoc Thread Scheduling Policies for Data Streaming Applications

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    In modern Stream Processing Engines (SPEs), numerous diverse applications, which can differ in aspects such as cost, criticality or latency sensitivity, can co-exist in the same computing node. When these differences need to be considered to control the performance of each application, custom scheduling of operators to threads is of key importance (e.g., when a smart vehicle needs to ensure that safety-critical applications always have access to computational power, while other applications are given lower, variable priorities).Many solutions have been proposed regarding schedulers that allocate threads to operators to optimize specific metrics (e.g., latency) but there is still lack of a tool that allows arbitrarily complex scheduling strategies to be seamlessly plugged on top of an SPE. We propose Haren to fill this gap. More specifically, we (1) formalize the thread scheduling problem in stream processing in a general way, allowing to define ad-hoc scheduling policies, (2) identify the bottlenecks and the opportunities of scheduling in stream processing, (3) distill a compact interface to connect Haren with SPEs, enabling rapid testing of various scheduling policies, (4) illustrate the usability of the framework by integrating it into an actual SPE and (5) provide a thorough evaluation. As we show, Haren makes it is possible to adapt the use of computational resources over time to meet the goals of a variety of scheduling policies
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