Localization Based on Parallel Robots Kinematics as an Alternative to Trilateration

In this work a new scheme for range-based localization is proposed. The main goal is to estimate the position of a mobile point based on distance measurements from fixed devices, called anchors, and on inertial measurements. Due to the non-linear nature of the problem, an analytic relation to compute the position starting from these measurements does not exist, and often trilateration methods are used, generally based on least-square algorithms. The proposed scheme is based on the modelling of the localization process as a parallel robot, thereby methodologies and control algorithms used in the robotic area can be exploited. In particular, a closed loop control system is designed for tracking the position of a mobile point based on range measurements from fixed anchors, and it is shown a peculiar structure of the tracking error dynamics, whose allows an intuitive gain tuning and ensures global exponential stability. Moreover, it is also shown a nice connection between tuning parameters and rate of convergence of the estimation error. Experimental results confirm the validity of the proposed localization method

Trajectory robust control of autonomous quadcopters based on model decoupling and disturbance estimation

In this article, a systematic procedure is given for determining a robust motion control law for autonomous quadcopters, starting from an input–output linearizable model. In particular, the suggested technique can be considered as a robust feedback linearization (FL), where the nonlinear state-feedback terms, which contain the aerodynamic forces and moments and other unknown disturbances, are estimated online by means of extended state observers. Therefore, the control system is made robust against unmodelled dynamics and endogenous as well as exogenous disturbances. The desired closed-loop dynamics is obtained by means of pole assignment. To have a feasible control action, that is, the forces produced by the motors belong to an admissible set of forces, suitable reference signals are generated by means of differentiators supplied by the desired trajectory. The proposed control algorithm is tested by means of simulation experiments on a Raspberry-PI board by means of the hardware-in-the-loop method, showing the effectiveness of the proposed approach. Moreover, it is compared with the standard FL control method, where the above nonlinear terms are computed using nominal parameters and the aerodynamical disturbances are neglected. The comparison shows that the control algorithm based on the online estimation of the above nonlinear state-feedback terms gives better static and dynamic behaviour over the standard FL control method

Glucagon and Insulin Cooperatively Stimulate Fibroblast Growth Factor 21 Gene Transcription by Increasing the Expression of Activating Transcription Factor 4

Previous studies have shown that glucagon cooperatively interacts with insulin to stimulate hepatic FGF21 gene expression. Here we investigated the mechanism by which glucagon and insulin increased FGF21 gene transcription in primary hepatocyte cultures. Transfection analyses demonstrated that glucagon plus insulin induction of FGF21 transcription was conferred by two activating transcription factor 4 (ATF4) binding sites in the FGF21 gene. Glucagon plus insulin stimulated a 5-fold increase in ATF4 protein abundance, and knockdown of ATF4 expression suppressed the ability of glucagon plus insulin to increase FGF21 expression. In hepatocytes incubated in the presence of insulin, treatment with a PKA-selective agonist mimicked the ability of glucagon to stimulate ATF4 and FGF21 expression. Inhibition of PKA, PI3K, Akt, and mammalian target of rapamycin complex 1 (mTORC1) suppressed the ability of glucagon plus insulin to stimulate ATF4 and FGF21 expression. Additional analyses demonstrated that chenodeoxycholic acid (CDCA) induced a 6-fold increase in ATF4 expression and that knockdown of ATF4 expression suppressed the ability of CDCA to increase FGF21 gene expression. CDCA increased the phosphorylation of eIF2α, and inhibition of eIF2α signaling activity suppressed CDCA regulation of ATF4 and FGF21 expression. These results demonstrate that glucagon plus insulin increases FGF21 transcription by stimulating ATF4 expression and that activation of cAMP/PKA and PI3K/Akt/mTORC1 mediates the effect of glucagon plus insulin on ATF4 expression. These results also demonstrate that CDCA regulation of FGF21 transcription is mediated at least partially by an eIF2α-dependent increase in ATF4 expression

Gender Analysis of Students Performances in Matching and Completion Test Formats; A Chemistry Achievement Test

This study compared the difficulty and discriminatory indices of boys and girls in matching and completion test format of chemistry achievement test. The research design was a descriptive   survey   type, the sample consisted of four hundred (400) SS 111 Students randomly selected from eight (8) public Senior Secondary Schools in A do Local Government Area of Ekiti State, The instrument was made up of two parallel objective test format on Chemistry Review Questionnaire (matching and completion formats).The first is a 60-item matching test which is essentially a replica of the sixty 60-item completion test. Both tests were strictly based on the same content. The two instruments were administered simultaneously. Data collected were analysed for P-values and d-values using correlation analysis, t-test and z-test. Two hypotheses were generated and tested at 0.05 level of significance. The result of the analysis showed that there is significant difference between the performance of male and female students in the completion test format of chemistry test; there is significant difference between the performance of male and female students in the matching test format of chemistry achievement test. It was therefore asserted that completion test and matching test can be used as complementary test item with the other forms of test in use presently. Keywords: Matching Tests, Difficulty Index, Difficulty Level, Discriminating Index, Completion Items, Item

Sliding Mode Control of Quadratic Boost Converters Based on Min-Type Control Strategy

The paper deals with the control of a quadratic boost converter supplied by low-voltage energy sources, such as photovoltaic panels, fuel cells, or batteries. The control scheme consists of two control loops. A min-type controller governs the inner loop to force the current state of the nominal model to converge in a neighborhood of the equilibrium state. The external loop processes the output tracking error using an integrator, and it allows reconfiguring the converter's working point by changing the equilibrium state given in the input to the internal loop. This configuration assures both zero tracking error of the output voltage and robustness against load and input voltage variations and converter parameter uncertainties. The stability of the whole system is investigated using the hybrid system framework. The proposed control technique has been tested experimentally in a suitably developed (low-cost) setup, and the results show the effectiveness of the proposed approach

Comparative study of the physicochemical and bacteriological qualities of some drinking water sources in Abuja, Nigeria

Diseases caused by contaminated water consumption and poor hygiene are among the leading causes of death in children, the elderly and people with compromised immune system. The present study aims to assess the drinking water quality of some selected drinking water sources in the chosen study area using water quality index (WQI). Samples of drinking waters were collected from four different sources- river, sachet (packaged), borehole and well in Jabi, Abuja, Nigeria for physicochemical and bacteriological analyses using standard methods. With the exception of pH, river water had the highest content of all the physicochemical parameters examined. Excluding dissolved oxygen in river sample, the physicochemical parameters of the water sources were generally within the World Health Organization (WHO) standards. The bacteriological analyses revealed that the highest total coliform counts of 1.03 (0.08) x 102 cfu/ml were in the river sample while the least counts of 0.03 (0.00) x 102 cfu/ml were in the sachet water. All the  bacteriological values did not meet international standard as they were higher than WHO standard of zero per 100ml. Three bacterial isolates Escherichia coli, Pseudomonas spp and  Aeromonas spp, were isolated from well water while Pseudomonas spp and Proteus spp were isolated from borehole water. All other bacteria were isolated from the river. The study demonstrates that the safest drinking water source in Idu district, Jabi, Abuja is the sachet/packaged water while the least safe is the river water due to the presence of opportunistic pathogens. Theresults of this study are beneficial for water quality management and could be used for low-cost effective water quality assessment in Jabi.Keywords: Bacterial isolates, Abuja, water sources,  physicochemical parameters, bacteriological parameter

Ethnic Conflict and Sustainable Development in Nigeria: The Role of Peace Education

The issue of ethnic conflict in Nigeria has become a burning national issue with its attendant problems. Its current predominance is reflected in the reports of various activities of ethnic militant in the country coupled with the high rising terrorism activities in the northern part of the country from which the traces of ethnicity problem cannot be totally ruled out. However, the issue now nationwide is no longer the recognition of ethnic conflict and its increasing threats to lives and properties but on how to curtail and manage it so that both human and material resources being used for such activities can be geared towards bringing about sustainable development in all spheres of life. The problem could best be tackled through deliberate and sincere efforts to change the behaviour and attitudes of the people to become their brothers’ keeper and tolerate one another. This could best be achieved upon the teaching of peace education in the schools. Therefore, this paper discusses ethnic conflict, reviews its trends and management and finally highlights the strategy for ethnic conflictresolution and management in Nigeria

Observability of a 2-branch Double-Layer-Capacitor

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RaGOO: fast and accurate reference-guided scaffolding of draft genomes

We present RaGOO, a reference-guided contig ordering and orienting tool that leverages the speed and sensitivity of Minimap2 to accurately achieve chromosome-scale assemblies in minutes. After the pseudomolecules are constructed, RaGOO identifies structural variants, including those spanning sequencing gaps. We show that RaGOO accurately orders and orients 3 de novo tomato genome assemblies, including the widely used M82 reference cultivar. We then demonstrate the scalability and utility of RaGOO with a pan-genome analysis of 103 Arabidopsis thaliana accessions by examining the structural variants detected in the newly assembled pseudomolecules. RaGOO is available open source at https://github.com/malonge/RaGOO