1,732 research outputs found

    QoS Constrained Optimal Sink and Relay Placement in Planned Wireless Sensor Networks

    Full text link
    We are given a set of sensors at given locations, a set of potential locations for placing base stations (BSs, or sinks), and another set of potential locations for placing wireless relay nodes. There is a cost for placing a BS and a cost for placing a relay. The problem we consider is to select a set of BS locations, a set of relay locations, and an association of sensor nodes with the selected BS locations, so that number of hops in the path from each sensor to its BS is bounded by hmax, and among all such feasible networks, the cost of the selected network is the minimum. The hop count bound suffices to ensure a certain probability of the data being delivered to the BS within a given maximum delay under a light traffic model. We observe that the problem is NP-Hard, and is hard to even approximate within a constant factor. For this problem, we propose a polynomial time approximation algorithm (SmartSelect) based on a relay placement algorithm proposed in our earlier work, along with a modification of the greedy algorithm for weighted set cover. We have analyzed the worst case approximation guarantee for this algorithm. We have also proposed a polynomial time heuristic to improve upon the solution provided by SmartSelect. Our numerical results demonstrate that the algorithms provide good quality solutions using very little computation time in various randomly generated network scenarios

    Metallic monoclinic phase in VO2_2 induced by electrochemical gating: in-situ Raman study

    Full text link
    We report in-situ Raman scattering studies of electrochemically top gated VO2_2 thin film to address metal-insulator transition (MIT) under gating. The room temperature monoclinic insulating phase goes to metallic state at a gate voltage of 2.6 V. However, the number of Raman modes do not change with electrolyte gating showing that the metallic phase is still monoclinic. The high frequency Raman mode Ag_g(7) near 616 cm1^{-1} ascribed to V-O vibration of bond length 2.06 \AA~ in VO6_6 octahedra hardens with increasing gate voltage and the Bg_g(3) mode near 654 cm1^{-1} softens. This shows that the distortion of the VO6_6 octahedra in the monoclinic phase decreases with gating. The time dependent Raman data at fixed gate voltages of 1 V (for 50 minute, showing enhancement of conductivity by a factor of 50) and 2 V (for 130 minute, showing further increase in conductivity by a factor of 5) show similar changes in high frequency Raman modes Ag_g(7) and Bg_g(3) as observed in gating. This slow change in conductance together with Raman frequency changes show that the governing mechanism for metalization is more likely to the diffusion controlled oxygen vacancy formation due to the applied electric field.Comment: 5 pages, 6 figure

    Streaming Video QoE Modeling and Prediction: A Long Short-Term Memory Approach

    Get PDF
    HTTP based adaptive video streaming has become a popular choice of streaming due to the reliable transmission and the flexibility offered to adapt to varying network conditions. However, due to rate adaptation in adaptive streaming, the quality of the videos at the client keeps varying with time depending on the end-to-end network conditions. Further, varying network conditions can lead to the video client running out of playback content resulting in rebuffering events. These factors affect the user satisfaction and cause degradation of the user quality of experience (QoE). It is important to quantify the perceptual QoE of the streaming video users and monitor the same in a continuous manner so that the QoE degradation can be minimized. However, the continuous evaluation of QoE is challenging as it is determined by complex dynamic interactions among the QoE influencing factors. Towards this end, we present LSTM-QoE, a recurrent neural network based QoE prediction model using a Long Short-Term Memory (LSTM) network. The LSTM-QoE is a network of cascaded LSTM blocks to capture the nonlinearities and the complex temporal dependencies involved in the time varying QoE. Based on an evaluation over several publicly available continuous QoE databases, we demonstrate that the LSTM-QoE has the capability to model the QoE dynamics effectively. We compare the proposed model with the state-of-the-art QoE prediction models and show that it provides superior performance across these databases. Further, we discuss the state space perspective for the LSTM-QoE and show the efficacy of the state space modeling approaches for QoE prediction

    SUPPLEMENTATION OF Α-LIPOIC ACID IN DIABETIC PERIPHERAL NEUROPATHY: A PROSPECTIVE OPEN LABEL RANDOMIZED CONTROLLED TRIAL

    Get PDF
    Abstract Objective: Diabetic peripheral neuropathy is the most common long term complications associated with reduced nerve conduction and blood flow. The present study was designed to investigate the effect of oral supplementation of α-lipoic acid (600 mg/day) on peripheral, sensory and motor nerve conduction and glycaemic control in type 2 diabetes mellitus with peripheral neuropathy. Methods: A total of 20 patients were enrolled in this study, then randomly allocated to two groups control (n=10) and intervention group (n=10). Patients in control group received only oral hypoglycaemic treatment and in intervention group received α-lipoic acid (600 mg/day) oral supplementation along with their oral hypoglycaemic treatment for a period of 3 months. Nerve conduction and glycaemic control were measured at the base line and at the end of 3 months by using specific methods. Results: In intervention group α-lipoic acid supplementation significantly improves 6 of 15 electrophysiological parameters of nerve conduction. Distal latency of peroneal (mean ± SD 5.13 ± 0.52 vs 4.92±0.55; p<0.02), median (mean ± SD 3.66 ± 0.76 vs 3.53±0.63; p<0.03) & ulnar motor nerves (mean ± SD 2.91 ± 0.32 vs 2.82±0.36; p<0.01), and Nerve Conduction Velocity of peroneal (mean ± SD 42.0 ± 3.07 vs 43.4±2.13; p<0.03), median (mean ± SD 51.4 ± 3.31 vs 52.2±3.59; p<0.01) & ulnar motor nerves (mean ± SD 51.0 ± 5.84 vs 52.1±5.46; p<0.03) shows significant improvement. Conclusion: Oral supplementation of α-lipoic acid was found to be effective in improving motor nerve conduction of upper and lower extremities in patients with diabetic peripheral neuropathy

    Enhanced hard x-ray emission from microdroplet preplasma

    Get PDF
    We perform a comparative study of hard x-ray emission from femtosecond laser plasmas in 15 mu m methanol microdroplets and Perspex target. The hard x-ray yield from droplet plasmas is similar or equal to 68 times more than that obtained from solid plasmas at 2x10(15) W cm(-2). A 10 ns prepulse at about 5% of the main pulse appears to be essential for hard x-ray generation from droplets. Hot electron temperature of 36 keV is measured from the droplets at 8x10(14) W cm(-2), whereas a three times higher intensity is needed to obtain similar hot electron temperatures from Perspex plasmas. Particle-in-cell simulations with very long scale-length density profiles support experimental observations. (c) 2006 American Institute of Physics

    Assessment of Antisocial Behaviour in the Juveniles

    Get PDF
    Background: High level of crime, particularly by the people below 18 years, has been a matter of concern for many years. Assessing and preventing the antisocial behaviour in juveniles has become a policy priority.Methods: A cross sectional study was conducted on 52 males less than 18 years in an observation home in Bangalore, India. The data was collected in an interview by filling a semi structured questionnaire. Revised Wisconsin Delinquency Risk Assessment Scale (RWDRAS) was filled up simultaneously and then results were analysed.Results: Majority of the offenders were in the age group 16-18 years. In the majority the cause for antisocial behaviour was unknown followed by the family problems and poverty. The RWDRAS identified 47% of the juveniles with antisocial behaviour as low risk group.Conclusion: The Education, counselling and prevention of poverty are some of the preventive measures of antisocial behaviour. There is a need to develop a better criteria and scale for the diagnosis of antisocial behaviour as the presently used RWDRAS failed in 47% of the juveniles

    Tropical storm off Myanmar coast sweeps reefs in Ritchie’s Archipelago, Andaman

    Get PDF
    The reefs in some islands of Andaman and Nicobar suffered severe damage following a tropical storm in the Bay of Bengal off Myanmar coast during 13–17 March 2011. Surveys were conducted at eight sites in Andaman, of which five were located in the Ritchie’s Archipelago where maximum wind speeds of 11 ms-1 was observed; and three around Port Blair which lay on the leeward side of the storm and had not experienced wind speeds of more than 9 ms-1. Corals in the shallow inshore reefs were broken and dislodged by the thrust of the waves. Significant damage in the deeper regions and offshore reefs were caused by the settlement of debris and sand brought down from the shallower regions. The fragile branching corals (Acropora sp.) were reduced to rubbles and the larger boulder corals (Porites sp.) were toppled over or scarred by falling debris. The reefs on the windward side and directly in the path of the storm winds were the worst affected. The investigation exposes the vulnerability of the reefs in Andaman to the oceanographic features which generally remain unnoticed unless the damage is caused to the coastal habitats

    Zero Energy Overwinter Storage of Apple Nursery Plants in trans-Himalayan Ladakh, India

    Get PDF
    Studies were conducted during 2015 and 2016 to assess the effects of storage conditions on survival of nursery plants in trans-Himalayan Ladakh region. Apple nursery plants raised under warm climatic conditions of Solan (Himachal) were lifted from nurseries in first week of January and stored upto March in cold Ladakh region. Underground cellar-stored plants showed significantly higher plant survival (92 to 94%) than greenhouse-stored plants (37 to 56% survival). Low and constant temperature (-1.5±4.1 to 10.0±1.4ºC) and absence of light inside the cellar were favorable factors for storage of nursery plants. Lower survival rates of greenhouse-stored plants could be attributed to lower and greater fluctuations in temperature (-9.3±1.7to 25.1±1.9ºC) inside the greenhouse. Cellar-stored plants were less subjected to freezing injury as reflected from shoot electrolyte leakage studies. The underground cellar was found effective for overwinter storage of apple nursery plants for 3 to 4 months. The method described is easy and cost-effective, and can be a satisfactory alternative to refrigerated cold storage in trans-Himalayan region with severe winters.
    corecore