Robust vehicle suspension system by converting active and passive control of a vehicle to semi-active control ystem analytically

This research article deals with a simplified translational model of an automotive suspension system which is constructed by considering the translation motion of one wheel of a car. Passive Vehicle Suspension System is converted into Semi Active Vehicle System. Major advantage achieved by this system is that it adjusts the damping of the suspension system without the application of any actuator by using MATLAB® simulations. The semi-active control is found to control the vibration of suspension system very well

Investigation of electrical properties for cantilever-based piezoelectric energy harvester

In the present era, the renewable sources of energy, e.g., piezoelectric materials are in great demand. They play a vital role in the field of micro-electromechanical systems, e.g., sensors and actuators. The cantilever-based piezoelectric energy harvesters are very popular because of their high performance and utilization. In this research-work, an energy harvester model based on a cantilever beam with bimorph PZT-5A, having a substrate layer of structural steel, was presented. The proposed energy scavenging system, designed in COMSOL Multiphysics, was applied to analyze the electrical output as a function of excitation frequencies, load resistances and accelerations. Analytical modeling was employed to measure the output voltage and power under pre-defined conditions of acceleration and load resistance. Experimentation was also performed to determine the relationship between independent and output parameters. Energy harvester is capable of producing the maximum power of 1.16 mW at a resonant frequency of 71 Hz under 1g acceleration, having load resistance of 12 k Omega. It was observed that acceleration and output power are directly proportional to each other. Moreover, the investigation conveys that the experimental results are in good agreement with the numerical results. The maximum error obtained between the experimental and numerical investigation was found to equal 4.3%

Iterative Residual Fitting for Spherical Harmonic Transform of Band-Limited Signals on the Sphere: Generalization and Analysis

We present the generalized iterative residual fitting (IRF) for the computation of the spherical harmonic transform (SHT) of band-limited signals on the sphere. The proposed method is based on the partitioning of the subspace of band-limited signals into orthogonal subspaces. There exist sampling schemes on the sphere which support accurate computation of SHT. However, there are applications where samples~(or measurements) are not taken over the predefined grid due to nature of the signal and/or acquisition set-up. To support such applications, the proposed IRF method enables accurate computation of SHTs of signals with randomly distributed sufficient number of samples. In order to improve the accuracy of the computation of the SHT, we also present the so-called multi-pass IRF which adds multiple iterative passes to the IRF. We analyse the multi-pass IRF for different sampling schemes and for different size partitions. Furthermore, we conduct numerical experiments to illustrate that the multi-pass IRF allows sufficiently accurate computation of SHTs

Fluorescence emission spectra of silver and silver/cobalt nanoparticles

AbstractVarious aqueous solutions of silver and silver/cobalt nanoparticles (Ag and Ag/Co NPs) were obtained, and their fluorescence emission spectra have been studied. First, colloidal Ag NPs were prepared by an electrochemical method under different time intervals and at different rotation speeds of rotating electrode. Next, in a reduction method, Ag/Co core–shell NPs were prepared, using Ag NPs as a core. The core–shell structure of Ag/Co NPs has been demonstrated by the Transmission Electron Micrograph (TEM) and X-Ray Diffraction (XRD) pattern. The fluorescence emission spectra of Ag and Ag/Co NPs, at different ranges of excitation wavelength, were investigated, which revealed two kinds of fluorescence emission peak. The shorter emission peak was fixed at about 485 (for Ag NPs) and 538 nm (for Ag/Co NPs). For both NPs, with an increase in excitation wavelength, the latter emission peak becomes red-shifted. The effect of duration time and rotation speed of the rotating electrode, in the electrochemical preparation of Ag NPs, on its fluorescence emission spectra, has also been investigated

Socio-demographic and economic correlates of climate change coping and adaptation strategies : a study on the farmer communities in Barisal District, Bangladesh

The major objective of the study is to apply Conservation of Resource (COR) theory for examining the influence of farmers’ socio-demographic and economic correlates upon their adoption of agricultural, economic and emotion-focused coping and adaptation strategies of climate change. An interview schedule developed from the COR theory was utilized for data collection. Using multistage cluster sampling technique, a total of 384 farmers were chosen from Agailjhara Upazila of Barisal District and interviewed through a predesigned structured questionnaire. For triangulation of the quantitative findings, the study employed case study technique to collect qualitative data from the respondents. The findings of the study demonstrate that the most common emotion-focused, agricultural and economic coping and adaptation strategies of climate change were social support seeking (79.69%), planting trees (71.35%), homestead gardening (52.08%), hydroponic farming/floating garden (46.88%), duck rearing (30.73%), saving (20.83%), self-insurance (18.75%), etc. Bivariate results indicate that age, ownership of land, income and ownership of television or mobile phone were found significantly correlated with the three variables, including economic, agricultural and emotion-focused coping and adaptation strategies of COR theory. Again, access to microcredit has relationship with economic and agricultural adaptation strategies. Furthermore, education has significant relationship with agricultural adaptation strategies. The study suggests that continuous researches by policy makers, researchers, GOs and NGOs are very essential to exploring and enhancing farmers’ coping and adaptation strategies which may relegate the adverse impacts and vulnerabilities of climate change in the study area

Recovering the state sequence of hidden Markov models using mean-field approximations

Inferring the sequence of states from observations is one of the most fundamental problems in Hidden Markov Models. In statistical physics language, this problem is equivalent to computing the marginals of a one-dimensional model with a random external field. While this task can be accomplished through transfer matrix methods, it becomes quickly intractable when the underlying state space is large. This paper develops several low-complexity approximate algorithms to address this inference problem when the state space becomes large. The new algorithms are based on various mean-field approximations of the transfer matrix. Their performances are studied in detail on a simple realistic model for DNA pyrosequencing.Comment: 43 pages, 41 figure

Diversity analysis of maize inbred lines using DIVA-GIS under temperate ecologies

The vagaries of Climate Change variability need to be addressed and as climatic conditions change at particular experimental sites and maize producing regions, mega-environment assignments will need to be reassessed to guide breeders to appropriate new germplasm and target environments . The development of improved germplasm to meet the needs of future generations in light of climate change and population growth is of the upmost importance . Evaluation of the inbred lines from diverse ecosystems would be effective for production of lines with resilience towards climate variability. Hence, with this objective diverse set of inbred lines sourced from all over India were characterized and were evaluated with DIVA-GIS for diversity analysis of maize inbred lines. Grid maps generated for these maize inbred lines for eleven quantitative traits indicated that these lines can be sourced from North and South India. High Shannon diversity index with maximum range of 2.17-3.0, 2.25-3.0, 2.36-3.0, 2.4-4.0, 2.0-3.0, and 2.2-3.0 were recorded for the traits viz; plant height, ear height, grain weight, grain yield, kernel row and protein content respectively indicating the high response of these traits to ecosystem. However, inbred lines were found to be diverse for all the traits except for ears plant-1 (EPP) and they have been sourced from Northern and Southern parts of India while for EPP recorded less diversity index range of 0.4-1.0 indicating source from South India. Interestingly, less diverse inbred lines for all the eleven quantitative traits have been sourced from Indogangetic plains as indicated in diversity grid maps. Maximum diversity indices were recorded for anthesis silking interval (ASI), days to silking, days to tasseling, which are in the range of 0.97-2.0, 1.528-2.0, 1.516-2.0 and 1.528-2.0 respectively. Hence, DIVA-GIS enabled identification of diverse sources from varied ecosystems which can be used for developing improved lines/ cultivars with greater resilience towards climate change