Computational aspects of helicopter trim analysis and damping levels from Floquet theory

Helicopter trim settings of periodic initial state and control inputs are investigated for convergence of Newton iteration in computing the settings sequentially and in parallel. The trim analysis uses a shooting method and a weak version of two temporal finite element methods with displacement formulation and with mixed formulation of displacements and momenta. These three methods broadly represent two main approaches of trim analysis: adaptation of initial-value and finite element boundary-value codes to periodic boundary conditions, particularly for unstable and marginally stable systems. In each method, both the sequential and in-parallel schemes are used and the resulting nonlinear algebraic equations are solved by damped Newton iteration with an optimally selected damping parameter. The impact of damped Newton iteration, including earlier-observed divergence problems in trim analysis, is demonstrated by the maximum condition number of the Jacobian matrices of the iterative scheme and by virtual elimination of divergence. The advantages of the in-parallel scheme over the conventional sequential scheme are also demonstrated

PREPARATION AND ANALYTICAL STUDY OF RASKARPUR

Parad Murchana is the backbone of Rasashastra which is a branch of Ayurveda.  Murchana signifies the formulations of mercury after Shodhan (purification). Parad can only be utilized therapeutically post Murchana. It is broadly classified into Sagandha (mercury with Gandhak) and Nirgandha (mercury without Gandhak) and each of it is further classified (for better learning) into Kharaliya, Parpati, Pottali and Kupupakva kalpanas, the later being better than the former with respect to its potency and action. This is due to the increased duration of Agni sanskara (heat given) as rightly quoted by Charaka in Charak Sanhita that Sanskar increases Guna (properties). Raskarpur is a Kupipakva-nirgandha kalpana. Nirgandha kalpana have always held a secondary status as compared to the Sagandha as the later are termed safer to use than the former. Mercury when combined with Gandhak (sulphur) becomes stable and less toxic. Nirgandha on the other hand needs to be administered in a proper dosage and for an appropriate duration only. This research is an attempt to study a Nirgandha kalpana and thus Raskarpur was taken . All the various versions of Raskarpur were studied and finally the Rastarangini version was selected. In order to bring uniformity in the drug prepared 2 batches of Raskarpur were prepared. This also helped to standardize the process. It was observed that the compound HgCl was formed at 100-1100. Raskarpur once prepared was tested for confirmation of the compound formed. During analysis 1 market sample was randomly taken and all 3 Raskarpur samples were analysed with their results compared with the standards. It was found that the percentage of Hg was very low as compared to the standards, that of the market sample being the lowest. The reason for the same needs to be evaluated. This study is a first attempt towards studying Raskarpur further research needs to be done using other versions

Design, Simulation of Low Actuation RF MEMS Shunt Switches With Electromagnetic Characterization

Micro Electro Mechanical Systems (MEMS) is an integration of sensors, actuators, microstructures and microelectronics. Components of MEMS that comprises of moving sub milli-meter sized parts, capable of providing Radio Frequency (RF) functionality are collectively referred as RF MEMS. In this work, low actuation RF MEMS switches have been designed and simulated and they have also been analysed for electromagnetic characterization. The switches so analyzed show an actuation voltage of as low as 2V. The electromagnetic analysis gives an isolation of as high as 55-65dB and a very low insertion loss of 0.01dB. DOI: 10.17762/ijritcc2321-8169.15068

Motion of falling object

A simple setup was assembled to study the motion of an object while it falls. The setup was used to determine the instantaneous velocity, terminal velocity and acceleration due to gravity. Also, since the whole project was done within $20 it can easily be popularized.Comment: 11 pages, 4 figur

Predictions of Control Inputs, Periodic Responses and Damping Levels of an Isolated Experimental Rotor in Trimmed Flight

Since the early 1990s the Aeroflightdynamics Directorate at the Ames Research Center has been conducting tests on isolated hingeless rotors in hover and forward flight. The primary objective is to generate a database on aeroelastic stability in trimmed flight for torsionally soft rotors at realistic tip speeds. The rotor test model has four soft inplane blades of NACA 0012 airfoil section with low torsional stiffness. The collective pitch and shaft tilt are set prior to each test run, and then the rotor is trimmed in the following sense: the longitudinal and lateral cyclic pitch controls are adjusted through a swashplate to minimize the 1/rev flapping moment at the 12 percent radial station. In hover, the database comprises lag regressive-mode damping with pitch variations. In forward flight the database comprises cyclic pitch controls, root flap moment and lag regressive-mode damping with advance ratio, shaft angle and pitch variations. This report presents the predictions and their correlation with the database. A modal analysis is used, in which nonrotating modes in flap bending, lag bending and torsion are computed from the measured blade mass and stiffness distributions. The airfoil aerodynamics is represented by the ONERA dynamic stall models of lift, drag and pitching moment, and the wake dynamics is represented by a state-space wake model. The trim analysis of finding, the cyclic controls and the corresponding, periodic responses is based on periodic shooting with damped Newton iteration; the Floquet transition matrix (FTM) comes out as a byproduct. The stabillty analysis of finding the frequencies and damping levels is based on the eigenvalue-eigenvector analysis of the FTM. All the structural and aerodynamic states are included from modeling to trim analysis. A major finding is that dynamic wake dramatically improves the correlation for the lateral cyclic pitch control. Overall, the correlation is fairly good

Active faulting in apparently stable peninsular India: Rift inversion and a Holocene-age great earthquake on the Tapti Fault

We present observations of active faulting within peninsular India, far from the surrounding plate boundaries. Offset alluvial fan surfaces indicate one or more magnitude 7.6–8.4 thrust-faulting earthquakes on the Tapti Fault (Maharashtra, western India) during the Holocene. The high ratio of fault displacement to length on the alluvial fan offsets implies high stress-drop faulting, as has been observed elsewhere in the peninsula. The along-strike extent of the fan offsets is similar to the thickness of the seismogenic layer, suggesting a roughly equidimensional fault rupture. The subsiding footwall of the fault is likely to have been responsible for altering the continental-scale drainage pattern in central India, and creating the large west-flowing catchment of the Tapti river. A pre-existing sedimentary basin in the uplifting hangingwall implies the Tapti Fault was active as a normal fault during the Mesozoic and has been reactivated as a thrust, highlighting the role of pre-existing structures in determining the rheology and deformation of the lithosphere. The slip sense of faults and earthquakes in India suggests that deformation south of the Ganges foreland basin is driven by the compressive force transmitted between India and the Tibetan Plateau. The along-strike continuation of faulting to the east of the Holocene ruptures we have studied represents a significant seismic hazard in central India.RCUKDOI: 10.1002/2014JB011294This is the final version of the following article: A. Copley, S. Mitra, R.A. Sloan, S. Gaonkar, and K. Reynolds, Active faulting in apparently stable peninsular India: rift inversion and a Holocene-age great earthquake on the Tapti Fault, Journal of Geophysical Research, which is also available at http://dx.doi.org/10.1002/2014JB011294

Sensitivity of lag-damping correlations to structural and aerodynamic approximations of isolated experimental rotors in forward flight

The predictions of regressive lag-mode damping levels are correlated with the database of an isolated, soft-inplane, three-blade rotor operated untrimmed. The database was generated at the Army Aeroflightdynamics Directorate at Ames. The correlation covers a broad range of data, from near-zero thrust conditions in hover to high-thrust and highly stalled conditions in forward flight with advance ratio as high as 0.55 and shaft angle as high as 20 degrees. In the experimental rotor, the airfoil or blade portion has essentially uniform mass and stiffness distributions, but the root flexure has highly nonuniform mass and stiffness distributions. Accordingly, the structural approximations refer to four models of root-flexure-blade assembly. They range from a rigid flap-lag model to three elastic flap-lag-torsion models, which differ in modeling the root flexure. The three models of root-flexure are: three root springs in which the bending-torsion couplings are fully accounted for; a finite-length beam element with some average mass and stiffness distributions such that the fundamental frequencies match those of the experimental model; and accurate modal representation in which the actual mass and stiffness distributions of the experimental root-flexure-blade assembly are used in calculating the nonrotating mode shapes. The four models of root-flexure-blade assembly are referred to as the rigid flap-lag model, spring model, modified model and modal model. For each of these four models of the root-flexure-blade assembly, the predictions are based on the following five aerodynamic theories: ear theory, which accounts for large angle-of-attack and reverse-flow effects on lift, and has constant drag and pitching moment; quasisteady stall theory, which includes quasisteady stall lift, drag and pitching moment characteristics of the airfoil section, dynamics stall theory, which uses the ONERA dynamic stall models of lift, drag and pitching moment; dynamic wake theory, which is based on a finite-state three-dimensional wake model and includes all wake effects including both shed and trailing vorticity; and dynamics and wake theory, which combines both dynamic stall theory and dynamic wake theory and is a relatively complete aerodynamic representation

SYNTHESIS AND ANTIBACTERIAL SCREENING OF FEW NEW 5-MEMBERED HETEROCYCLIC SUGAR HYDRAZONES

Objective: The aim of this study is to synthesize, characterize, and screen some new 5-membered heterocyclic sugar hydrazones for their antibacterialactivities.Methods: A library of sugar hydrazones containing 2-benzofuryl, 2-thiophenyl, and 2-pyrrolyl motifs were synthesized. Structures of the newlysynthesized compounds were deduced based on spectral data and elemental analyses.Results: Antibacterial activity was screened against Gram-positive and Gram-negative bacterial strains. Results were compared to gentamicin.Compound 6a exhibited most potent antibacterial activity against all the tested strains.Conclusion: 2-benzofuryl derivatives were observed to be good antibacterials.Keywords: Benzofuran, Thiophene, Pyrrole, Antibacterial, Sugar

Simple Pendulum Revisited

We describe a 8085 microprocessor interface developed to make reliable time period measurements. The time period of each oscillation of a simple pendulum was measured using this interface. The variation of the time period with increasing oscillation was studied for the simple harmonic motion (SHM) and for large angle initial displacements (non-SHM). The results underlines the importance of the precautions which the students are asked to take while performing the pendulum experiment.Comment: 17 pages with 10 figure

Exploring Fuzzy Set Concept in Priority Theory for Maintenance Strategy Selection Problem

This paper proposes and presents a different approach of choosing an appropriate maintenance strategy using Saaty’s priority theory and fuzzy sets. As per the priority theory, weights are assigned to the decision criteria via pair wise comparison of criteria. Basic three types of maintenance strategies specifically corrective maintenance, preventive maintenance and predictive maintenance and eight maintenance decision criteria namely low maintenance cost, improved reliability, improved safety, high product quality, minimum inventory, return on investment, acceptance by labor, enhanced competitiveness have been considered to evaluate the most favorable strategy. Instead of usual practice of considering single value for “intensity of importance” factor, more appropriate triangular fuzzy numbers are used to represent it. A different approach using fuzzy arithmetic (α-cuts) in priority theory for the above stated problem has been investigated in this paper