Showing papers by "National Institute of Technology, Meghalaya published in 2022"

Distributed Reinforcement Learning for scalable wireless medium access in IoTs and sensor networks

Abstract: This paper presents a distributed Reinforcement Learning (RL) framework for synthesizing wireless network protocols in IoT and Wireless Sensor Networks with low-complexity transceivers . Wireless medium access control (MAC) behavior is first formulated as a Multi-agent Markov Decision Process (MAMDP), and then solved using distributed Reinforcement Learning as a temporal difference MDP solution method. Since the proposed learning approach is distributed, it allows network nodes to independently learn optimal MAC-layer transmission strategies for maximizing network throughput. It is shown that by learning with limited network information from up to two-hop neighborhoods, the proposed paradigm can offer network throughput that is comparable with the known benchmark obtained from the ALOHA family of protocols. It is also demonstrated that unlike with ALOHA, the proposed RL based MAC layer can adjust its transmission strategies such that the maximum throughout can be sustained at higher and heterogenous traffic load conditions. Another distinctive feature of the proposed mechanism is that the wireless bandwidth can be shared more equitably than the benchmark ALOHA, especially in the presence of load and topological heterogeneities. The mechanism is also able to change nodes’ access priorities parametrically while learning, which can be useful for sensing applications with heterogeneous wireless bandwidth needs. Finally, the online MAC learning abilities are shown to be able to adjust nodes’ transmission policies on the fly in a dynamic network traffic environment.

Design and Development of the Pineapple Harvesting Robotic Gripper

Abstract: Applications of robot in various fields like industrial automation, mining, space application, medical science, and agriculture application have been increased with recent need and technological development. Recently, various researches reported the development of agricultural robot with suitable gripper for particular applications, like tomato harvesting, strawberry harvesting, apple harvesting, cherry harvesting, eggplant harvesting, cabbage harvesting, cucumber harvesting, and crop cutting. A lot of scope still is there to improve agriculture root. Development of the robot component with 3D printing increased due to first production capability, complex shape can be manufactured very easily. Recently, fused deposition modeling method is widely used for 3D printing to manufacture complicated parts of robot to develop working model. It has been found polylactic acid printing material with controlled printing condition that provides good strength of the printed parts. The Arduino UNO-based controller for actuation of the robotic system has become popular due to low cost, less energy requirement, and its simplicity. The northeastern region of India cultivates a lot of pineapples. Pineapple cultivation increased rapidly last two decades. The regions are mainly covered by hills, so the access of pineapple field by human has difficulty. The pineapple leaves are also very rough, which may cause human injury. Development of the robot for pineapple cropping can improve productivity and human comfort. Special type of gripper design has to be done for pineapple cropping application. In the present study, three fingers gripper cum cutter has been developed for pineapple harvesting application. Model of the gripper has been developed in CREO software based on the dimensional survey of the pineapple. Mechanical analysis of the 3D printed gripper components has been done to obtain final design of the gripper component. The gripper component has been manufactured through FDM 3D printing. Finally, the 3D printed gripper components have been assembled to develop working model. The Arduino UNO and Bluetooth module are integrated with servo motors for controlling the finger components, cutter arm, and cutter rotor.

Spatial patterns of fertilizer use and imbalances: Evidence from rice cultivation in India

Abstract: Fertilizer use immensely contributes to sustaining higher crop productivity and ensuring food security around the globe. However, the over-application of nitrogenous fertilizers resulted in negative environmental externalities. Thus, assessing imbalances in chemical fertilizer use is vital for environmental sustainability. This paper studies the pattern of imbalances in chemical fertilizer application as an indicator of environmental sustainability. Using district-level data for India, this study finds within-State heterogeneity in the fertilizer application. Spatial patterns for divergences from recommended norms in rice cultivation show the existence of districts with both excessive and deficit fertilizer applications. Many districts in the Indo-Gangetic plains use unsustainably excess fertilizer. Similarly, our results indicate large surpluses of nitrogen from partial nitrogen balance assessment in the region. The assessment of sustainability indicators helps identify regions for policy intervention targeting nutrient balance in the soil.

The Role of Zinc in Cardiovascular Disease

Abstract: Zinc is an essential trace element due to its role as a key part of human enzymatic activity. As a cofactor in metalloenzymes and metalloproteins, zinc participates in diverse biological functions, including gene transcription, translation, and replication, phagocytosis, and immunoglobulin and cytokine production. In this review, we will focus on the role of zinc in the cardiovascular system, including heart failure, vascular calcification, and myocardial infarction. We will further highlight the role of zinc in cardiovascular pathology in individuals with chronic kidney disease, and type II diabetes mellitus, groups uniquely at risk for cardiovascular morbidity and mortality.

Analysis of GFDM in generalized <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e1283" altimg="si285.svg"><mml:mrow><mml:mi>η</mml:mi><mml:mo linebreak="goodbreak" linebreakstyle="after">−</mml:mo><mml:mi>μ</mml:mi></mml:mrow></mml:math> fading channel: A simple probability density function approach for beyond 5G wireless applications

Abstract: Generalized frequency division multiplexing (GFDM) is a flexible radio waveform which offers high degree of freedom in varying the number of time slots, number of subcarriers, and pulse shaping filters. In addition to this, it also covers orthogonal frequency division multiplexing (OFDM) and single carrier frequency domain equalization (SC-FDE) as corner cases. A well-known fact is that the performance of a wireless communication system is predominately effected by the characteristics of the fading environment. In this paper, symbol error rate (SER) closed-form expression of GFDM system under the generalized η−μ fading channel is derived. The proposed derivation includes Rayleigh, Nakagami-m, and Nakagami-q fading channels as special cases. A Mote-Carlo simulation test-bed is carried out using MATLAB to compare with analytical results and to validate the derived expressions based on the probability density function (PDF) approach. Further, this paper investigates the performance of the GFDM system by varying various parameters such as fading values, pulse shaping filters, roll-off factor, and modulation order. The detailed analysis suggests that the probability of SER is highly dependent on the above parameters. The results obtained are more useful in evaluating the performance of GFDM based communication system in a generalized manner.

Rainfall shocks and fertilizer use: a district level study of India

Abstract: Abstract In the context of climate change and increasing occurrences of extreme events, it is essential to understand farmers' responses to weather shocks and adaptations. This paper uses a panel dataset of 311 selected Indian districts ranging from 1966 to 2009 to investigate how application of chemical fertilizers varies in response to rainfall shocks. Two rainfall shock measures are constructed based on deviation in rainfall from the normal, a categorical measure of rainfall shock; and another, a continuous index of negative rainfall deviation. Based on a panel fixed effect regression, the study finds no apparent reduction in the level of fertilizer use in negative rainfall shock years. However, with a one-year lagged rainfall shock, a reduction in fertilizer application rate is observed for the continuous drought index. Further, exposure to higher intensity droughts in the previous year leads to an increase in the amount of fertilizer application in the current year.

Induced Homeomorphism and Atsuji Hyperspaces

Abstract: Given uniformly homeomorphic metric spaces $$X$$ and $$Y$$ , it is proven that hyperspaces $$C(X)$$ and $$C(Y)$$ are uniformly homeomorphic, where $$C(X)$$ denotes the collection of all nonempty closed subsets of $$X$$ , and is endowed with Hausdorff distance. Gerald Beer has proved that hyperspace $$C(X)$$ is an Atsuji space when $$X$$ is either compact or uniformly discrete. An Atsuji space is a generalization of compact metric spaces as well as of uniformly discrete spaces. In this paper, we investigate space $$C(X)$$ when $$X$$ is an Atsuji space, and a class of Atsuji subspaces of $$C(X)$$ is obtained. Using the results, some fixed point results for continuous maps on Atsuji spaces are obtained.

Design and Implementation of Multi-operand 2$$^$$, 2$$^n$$n, and 2$$^n+1$$n+1 Modulo Set Adder

Abstract: In this paper, multi-operand modulo adders have been proposed and the adders have been designed based on a new 5:3 compressor. Gate-level design of such compressor has been carried out through the simplification of the K-map. The functionalities of the proposed modulo adders have been verified in the Xilinx 14.7 design environment implemented through VHDL coding. The performance parameters such as power consumption, delay, and power-delay product (PDP) have been obtained from the simulation using the device Virtex-6.

A Counter-Based Profiling Scheme for Improving Locality Through Data and Reducer Placement

Abstract: Hadoop has been regarded as the de-facto standard for handling data-intensive distributed applications with its popular storage and processing engine called as the Hadoop distributed File System (HDFS) and MapReduce. Hadoop’s inherent assumption of homogeneity in the cluster is a major cause of performance deterioration due to the huge shuffle required for the processing of data during map phase and reducer phase. This chapter addresses this performance deterioration by proposing a counter placement scheme (CPS) whose main contributions are enumerated as follows; (i) Profiling of nodes based on the completion of maps, (ii) Movement of high-performance nodes into a single rack for tracking higher computation, (iii) Data replacement strategy based on placing at least a single block of file in the rack with the highest computation, and (iv) Finally assigning reducers to the rack and node with highest computation. The experiments performed clearly signify the merits of CPS in terms of reduction in the average completion time, reduce time and off-local shuffle by about (1.9–22.83%), (2.1–21.5%), (4.25–24%) while running several benchmarks.

Analysis of Brinkman-Forchheimer extended Darcy's model in a fluid saturated anisotropic porous channel

Abstract: <p style='text-indent:20px;'>We present asymptotic analysis of Couette flow through a channel packed with porous medium. We assume that the porous medium is anisotropic and the permeability varies along all the directions so that it appears as a positive semidefinite matrix in the momentum equation. We developed existence and uniqueness results corresponding to the anisotropic Brinkman-Forchheimer extended Darcy's equation in case of fully developed flow using the Browder-Minty theorem. Complemented with the existence and uniqueness analysis, we present an asymptotic solution by taking Darcy number as the perturbed parameter. For a high Darcy number, the corresponding problem is dealt with regular perturbation expansion. For low Darcy number, the problem of interest is a singular perturbation. We use matched asymptotic expansion to treat this case. More generally, we obtained an approximate solution for the nonlinear problem, which is uniformly valid irrespective of the porous medium parameter values. The analysis presented serves a dual purpose by providing the existence and uniqueness of the anisotropic nonlinear Brinkman-Forchheimer extended Darcy's equation and provide an approximate solution that shows good agreement with the numerical solution.</p>

Simulation of Natural Gas Combustor Using CFD

Abstract: The combustors are the direct-fired heaters or burners where the fuel burns in stoichiometric composition and evolves an enormous amount of heat for process heating. The natural gas combustor utilizes natural gas as fuel for the combustion process. Several designs of natural gas combustors are available for the above-said process; based on the application, the design of the combustor is determined. The current research is motivated towards the CFD simulation of natural gas combustor using Species Transport model along with different Turbulence models (Standard k − ℇ, Realizable k − ℇ, RNG k − ℇ, Standard k − ω and SST k − ω) and Radiation models (Discrete Ordinate (DO), P1 and Rosseland) in two different simulation tools (Ansys Fluent and Star CCM+). The flow, thermal and combustion analysis of natural gas combustor is performed with the above-mentioned combustion, radiation and turbulence models in Ansys Fluent. The results obtained from the simulation using Ansys Fluent are compared with the available experimental results of Sayre et al. (Scaling Characteristics of Aerodynamics and Low-NOx Properties of Industrial Natural Gas Burners, The SCALING 400 Study, Part IV: The 300 kW BERL Test Results. International Flame Research Foundation, The Netherlands, 1994, [1]) to validate the adopted methodology. The best-predicted turbulence and radiation model, along with the Species Transport model, is used in Star CCM+. The simulated results in both the software are compared with the experimental results and are in close agreement.

Spectroscopic and luminescent properties of Ce3+ -doped TeO2-WO3-GeO2 glasses

Abstract: Different concentrations of Ce3+-doped TeO2-WO3-GeO2-Ce2O3 (TWGCe) glasses were prepared by melt-quenching method and characterized. Different spectroscopic and luminescence properties were evaluated using room temperature absorption and emission spectra. The absence of sharp X-ray diffraction peaks and the presence of broad band from 18° to 35° shows the amorphous phase of studied glasses. The Fourier transform infrared absorption spectra show the presence of various vibrational bonds. The optical properties of TWGCe glasses were studied by exciting the glass samples at 323 nm ultraviolet wavelength. The quenching in luminescence is noticed at × = 0.5 mol% along with a red-shift at higher Ce3+ concentrations. The decay time was found decrease with increase of concentration of Ce3+ ions. These glasses emit intense blue luminescence with CIE coordinates (0.161, 0.018) when excited at 323 nm radiation. These glasses are favourable as blue light sources in the design of phosphor-based white LEDs.

FEA-Based Prediction of Tensile and Flexural Properties of Green Composites Under Different Fiber Loading

Abstract: This study presents the tensile and flexural behavior of the natural fiber-based green composite. Unidirectional bamboo fiber and polylactic acid (PLA) were chosen to design and model the green composite. The tensile and flexural specimens of the green composite were modeled by using ABAQUS 6.14. The properties of the green composite were estimated by varying the fiber loading from 10 to 30 wt.%. The damage to the green composite was also predicted by using the Hashin damage criteria. The simulated results of tensile and flexural strength and modulus were also compared with the published experimental findings.

Wind Tunnel Experiments to Estimate the Performance of a Novel Arc-Elliptical-Bladed Savonius Wind Rotor

Abstract: The gradually exhausting non-renewable energy resources, pollution from conventional fuel resources and alarming global warming have sparked the interest in developing renewable technologies for power generation. In that connection, the vertical-axis drag-based Savonius wind turbine/rotor is an exciting prospect to harness the free energy available in the wind and can be deployed in remote areas having no electricity grids. The present study aims at designing and developing a vertical-axis Savonius wind rotor, and its subsequent testing in a wind tunnel. The key parameters affecting a Savonius rotor’s output are its blade shape, aspect ratio, overlap ratio and blade number. Considering the various aspects of blade design reported in the literature, a novel arc-elliptical-bladed Savonius wind rotor has been developed. The overlap ratio and aspect ratio are chosen to be 0.15 and 1.1:1, respectively. The testing of the rotor has been conducted in a subsonic wind tunnel under different loading conditions. The power coefficients are estimated for a range of tip-speed ratios. Further, its output characteristics have been compared with conventional semicircular-bladed Savonius rotor. The experiments reveal an improvement of 37% for arc-elliptical-bladed rotor as compared to semicircular-bladed rotor.

A Game Theoretic Group Coordination Strategy for Multi Robot Navigation

Abstract: Navigating multiple robots across a terrain to achieve their individual goals is a challenging research problem and has been addressed by incorporating a myriad of soft computing techniques. This article discusses this problem from the perspective of enacting a group coordination strategy among a group of robots. Such a scheme can go a long way in paving the path for quick and automatic disaster recovery through sharing critical information. Experiments have been carried out with four groups of robots with their respective sources and destinations and varying the number of robots between 8 to 20 with a novel game-theoretic group coordination strategy. Results obtained using the proposed approach have been compared with those obtained by traditional Potential Field Method (PFM) and standard soft computing based strategy such as Genetic Algorithm-Fuzzy (GA-Fuzzy) for performance metrics, both individual as well as for group, traveling time and the obtained results demonstrate the efficacy of the proposed method.

Writing Histories of Capital in the Shadow of War

Abstract: In November 2010, twenty-four heads of member states of NATO assembled for a summit in Lisbon. On their agenda was an overhaul of the alliance's decade-long security strategy. On the sidelines of this summit, the heads of government met with Afghan President Hamid Karzai and announced plans to withdraw all NATO troops from Afghanistan by the end of 2014. The decision was not wholly unexpected. However, in newsrooms and among select consulting firms that worked with Afghan ministries in the capital Kabul, the announcement ratcheted up a sense of unease. Doubts were cast over the Afghan national army's preparedness to carry out solo combat operations.

A Novel Fuzzy Logic-Controlled Vienna Rectifier to Extract Maximum Power in the Grid-Connected Wind Energy System Applications

Abstract: In this paper, a novel fuzzy logic-controlled Vienna rectifier to extract maximum power at variable wind speed is proposed. Vienna rectifier consists of three switches and four diodes with an input inductor and performs both AC/DC and DC/DC conversions in a single stage. A permanent magnet synchronous generator (PMSG) coupled with wind turbine system is used in this paper. The tracking of the maximum power is a real challenge in wind energy systems. In this paper, the variable speed of the wind turbine generator system and the power output of the permanent magnet synchronous generator are chosen as inputs to the fuzzy logic controller to track the maximum power according to the change in wind speed by following 27 set of rules formulated in the fuzzy rule base. The pulse width modulated signals from the fuzzy logic controller initiate the three switches in the Vienna rectifier. The proposed control scheme not only tracks the maximum power from the wind but also enhances the input DC voltage, ensures sinusoidal nature at input mains and balances the voltage across the two capacitors. The Vienna rectifier is interfaced to the grid through space vector pulse width modulated voltage source inverter. The MATLAB/Simulink environment is utilized in order to observe the optimum performance of the system. The proposed control algorithm is experimentally validated using a real-time simulator OPAL RT 4200. The experimental results are in agreement with simulation results and prove the robustness of the control scheme.