1,220 research outputs found

    Forming Gas Giants Around a Range of Protostellar M-dwarfs by Gas Disk Gravitational Instability

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    Recent discoveries of gas giant exoplanets around M-dwarfs (GEMS) from transiting and radial velocity (RV) surveys are difficult to explain with core-accretion models. We present here a homogeneous suite of 162 models of gravitationally unstable gaseous disks. These models represent an existence proof for gas giants more massive than 0.1 Jupiter masses to form by the gas disk gravitational instability (GDGI) mechanism around M-dwarfs for comparison with observed exoplanet demographics and protoplanetary disk mass estimates for M-dwarf stars. We use the Enzo 2.6 adaptive mesh refinement (AMR) 3D hydrodynamics code to follow the formation and initial orbital evolution of gas giant protoplanets in gravitationally unstable gaseous disks in orbit around M-dwarfs with stellar masses ranging from 0.1 M⊙M_\odot to 0.5 M⊙M_\odot. The gas disk masses are varied over a range from disks that are too low in mass to form gas giants rapidly to those where numerous gas giants are formed, therefore revealing the critical disk mass necessary for gas giants to form by the GDGI mechanism around M-dwarfs. The disk masses vary from 0.01 M⊙M_\odot to 0.05 M⊙M_\odot while the disk to star mass ratios explored range from 0.04 to 0.3. The models have varied initial outer disk temperatures (10 K to 60 K) and varied levels of AMR grid spatial resolution, producing a sample of expected gas giant protoplanets for each star mass. Broadly speaking, disk masses of at least 0.02 M⊙M_\odot are needed for the GDGI mechanism to form gas giant protoplanets around M-dwarfs.Comment: 34 pages, 8 figures, in press, Ap

    A Review and an Approach of Flying Electric Generators as Alternate Source of Energy

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    This paper presents a review of flying electric generators which are used to harness kinetic energy in powerful, persistent high altitude winds. It has been found that FEGs could give individual output of up to 40MW. It is a lighter wind turbine that rotates about a horizontal axis in response to wind, generating electrical energy. This electrical energy is transferred down for immediate use, or to a set of batteries for later use, or to the power grid. This paper presents the critical analysis of existing literature which is relevant to flying electric generator Though, the literature consists of a lot many research contributions, but, here, we have analyzed some important research and review papers. The existing approaches are categorized based on the basic concepts involved in the mechanisms. The emphasis is on the concepts used by the concerned authors, the database used for experimentations and the performance evaluation parameters. Their claims are also highlighted. Finally, the findings are summarized related to the studied and analyzed research papers. Paper concludes with the motivation behind identified problem

    A Review and an Approach of Water Pollution Indication using Arduino Uno

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    Drinking water is critical for the wellbeing and prosperity of all people and creatures because water play major role in all living beings and most danger disease are caused by water and it is our duty to provide clean and safe water and also to monitor the pollution level in water it is additionally essential for farming utilization for good product yielding and natural way of life linkage wellbeing issues. With over 200 children dying per day due to unsafe water, drinking water crisis is ranked one on the global risk by World Economic Forum, 2015. This paper presents an easy and comprehensive methodology is microcontroller sensor based system continuous observing and pollution recognition for both drinking and non-drinking water dissemination frameworks and in addition for customer locales

    Automatic Overhead Water Tank Cleaning System: A Review and an Approach

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    Aim of this paper is to develop a mechanical system for cleaning domestic cylindrical water tank. The mechanical system includes two main mechanisms which are rack and pinion gear mechanism and reciprocating four bar linkage mechanism. The rack and pinion arrangement is used to move whole mechanical system up and down for cleaning the cylindrical tank. The rack is fixed on the motor and the four-bar mechanism is attached to the motor shaft. PVC brushes are attached to the ends of the four-bar linkage. Four bar linkage is made in such a way that it can be adjusted according to inside diameter of the tank. When the motor is started the linkage rotates and with the help of brushes, cleaning of wall and base of tank takes place. The purpose of this project is to reduce the human efforts and to avoid the chemical influence on health of person entering the tank for cleaning. In this modern world, cleaning of overhead tanks manually is a tedious job. To overcome this we have aimed at tackling the disadvantages of cleaning overhead tanks, so an automatic system overhead tank cleaning is designed to provide high safety, high efficiency, less time for cleaning and to avoid environmental pollution problems. Purpose of this paper is to clean domestic cylindrical water tank with the help of mechatronics system. The mechatronics system consists of a grooved gear rod attached to two arms with brushes at ends. The two arms are connected to the gear rod by nut. By rotating the gear rod, the up and down motion of the two arms is achieved. The gear rod is rotated with the help of a D.C gear motor. The main grooved shaft is powered by an A.C motor. The motor and the shaft are connected by a rubber belt. The clockwise rotation of the main shaft will make the arms move and vice versa. The whole operation is controlled by a circuit consisting of relay switches, buttons, and PIC microcontroller. The number of times for the operation to repeat can be fed into the circuit. The achievement of this project is reduction of cost and manual labour because there will be harmful diseases for the person who will go inside and it will affect the health as well as the other human being who consumes water from the tank

    Multi-Shooting Differential Dynamic Programming for Hybrid Systems using Analytical Derivatives

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    Differential Dynamic Programming (DDP) is a popular technique used to generate motion for dynamic-legged robots in the recent past. However, in most cases, only the first-order partial derivatives of the underlying dynamics are used, resulting in the iLQR approach. Neglecting the second-order terms often slows down the convergence rate compared to full DDP. Multi-Shooting is another popular technique to improve robustness, especially if the dynamics are highly non-linear. In this work, we consider Multi-Shooting DDP for trajectory optimization of a bounding gait for a simplified quadruped model. As the main contribution, we develop Second-Order analytical partial derivatives of the rigid-body contact dynamics, extending our previous results for fixed/floating base models with multi-DoF joints. Finally, we show the benefits of a novel Quasi-Newton method for approximating second-order derivatives of the dynamics, leading to order-of-magnitude speedups in the convergence compared to the full DDP method.Comment: https://www.youtube.com/watch?v=C0h6mEpcnA

    Study on incidence of silent cerebral ischemia among diabetic nephropathy patients admitted in tertiary care hospital

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    Abstract: Background: Diabetes accelerates the atherosclerotic process in blood vessels, leading to micro- and macro vascular complications, stroke being one of these. Carotid artery atherosclerosis in patients with Diabetic nephropathy is found to be associated with Silent cerebral infarction (SCI). Present study was carried to found any relationship between carotid intima media thickness and silent cerebral infarction in patients with type 2 diabetic nephropathy.Methods: The study was done in 50 DN patients admitted in medicine ward of tertiary care hospital. Subjects were evaluated based on detailed clinical data like symptoms, signs, and associated illnesses, general and systemic examination. Subjects were diagnosed with silent cerebral infarct based on MRI Findings. Each subject had undergone MRI to find out incidence of SCI.Results: Maximum (54%) was in age group of 61-70yrs and very few (6%) were below age of 50yrs. M: F was 1.6:1. Around 44% had duration of diabetes in 1-5yrs of duration and very few (6%) had diabetes >15yrs. On USG scan of carotid vessels it was found that 86% had increased carotid intimal media thickness either or side of vessel. On MRI brain there was incidence of silent cerebral ischemia among 30% study subjects.Conclusion: Both CIMT and SBI showed rise in incidence with corresponds to increase in age, duration of diabetes and urine albumin level among study subjects.

    Evaluation of anti-psychotic effect of nimodipine using methylphenidate as a model to induce psychosis in albino mice

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    Background: Schizophrenia is a functional psychotic disorder currently treated by typical and atypical antipsychotic drugs. A large group of patients remain resistant to therapy. Nimodipine has been found effective for treating resistant bipolar mood disorder which is linked genetically with schizophrenia and has a high overlap of neurotransmitters in the etiopathology. Previous studies to evaluate nimodipine’s antipsychotic activity have shown inconsistent results. Methylphenidate, a CNS stimulant like amphetamine, has been shown to induce stereotypy in animals and can be proposed as an alternative model for psychosis.Methods: Methylphenidate 5 mg/kg was given intraperitoneally to induce psychosis in swiss albino mice (n=6). Nimodipine was given alone in doses of 2.5 and 5 mg/kg by i.p route and in combination with haloperidol 0.1 mg/kg and effects were compared with haloperidol 0.2mg/kg. Activity of nimodipine was also assessed on the haloperidol induced catalepsy test. Statistical analysis was done with ANOVA followed by Bonferroni’s test using SPSS v. 20.0.Results: Methylphenidate successfully induced characteristic stereotypy behaviour in mice similar to amphetamine. Both nimodipine 5 mg/kg and haloperidol 0.2 mg/kg showed significant reduction in stereotypy behaviour with no statistical difference between the two; result with nimodipine were only slightly inferior to haloperidol. Nimodipine 5 mg/kg with haloperidol 0.1 mg/kg showed significantly better activity than haloperidol in standard dose of 0.2 mg/kg. Nimodipine did not show significant activity on the haloperidol induced catalepsy test.Conclusions: Methylphenidate has potential to be used as an alternative model for inducing psychosis in animals and nimodipine shows promising results for use as adjuvant antipsychotic drug
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