Electromechanical and Dynamic Characterization of In-House-Fabricated Amplified Piezo Actuator

A diamond-shaped amplified piezo actuator (APA) fabricated using six multilayered piezo stacks with maximum displacement of 173 μm at 175V and the amplification factor of 4.3. The dynamic characterization of the actuator was carried out at different frequencies (100 Hz–1 kHz) and at different AC voltages (20V–40V). The actuator response over this frequency range was found neat, without attenuation of the signal. Numerical modeling of multilayered stack actuator was carried out using empirical equations, and the electromechanical analysis was carried out using ABAQUS software. The block force of the APA was 81 N, calculated by electromechanical analysis. This is similar to that calculated by dynamic characterization method

The effects of thermal radiation and viscous dissipation on MHD heat and mass diffusion flow past an oscillating vertical plate embedded in a porous medium with variable surface conditions

This investigation is undertaken to study the hydromagnetic flow of a viscous incompressible fluid past an oscillating vertical plate embedded in a porous medium with radiation, viscous dissipation and variable heat and mass diffusion. Governing equations are solved by unconditionally stable explicit finite difference method of DuFort - Frankel’s type for concentration, temperature, vertical velocity field and skin - friction and they are presented graphically for different values of physical parameters involved. It is observed that plate oscillation, variable mass diffusion, radiation, viscous dissipation and porous medium affect the flow pattern significantly

Novel mechanism for evaluating feedback in the grid environment on resource allocation

The primary concern in proffering an infrastructure for general purpose computational grids formation is security. Grid implementations have been devised to deal with the security concerns. The chief factors that can be problematic in the secured selection of grid resources are the wide range of selection and the high degree of strangeness. Moreover, the lack of a higher degree of confidence relationship is likely to prevent efficient resource allocation and utilization. In this paper, we propose an efficient approach for the secured selection of grid resources, so as to achieve secure execution of the jobs. The presented approach utilizes trust and reputation for securely selecting the grid resources by also evaluation user’s feedback on the basis of the feedback already available about the entities. The proposed approach is scalable for an increased number of resources

Methyl 4-(3-eth­oxy-4-hydroxy­phen­yl)-6-methyl-2-oxo-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate monohydrate

In the title compound, C15H18N2O5·H2O, the pyrimidine ring adopts a flattened-boat conformation. The eth­oxy group attached to the benzene ring is in an extended conformation. The oxopyrimidine mol­ecules are linked into centrosymmetric R 2 2(20) dimers by O—H⋯O hydrogen bonds. The dimers are linked by N—H⋯O hydrogen bonds, forming a two-dimensional network parallel to the bc plane. Adjacent networks are cross-linked via N—H⋯O and O—H⋯O hydrogen bonds involving the water mol­ecules

Analysis of SPWM Technique for Solar Inverter

Reactive power control is necessary to maintain power system stable. In a three phase grid connected PV system, the inverter should regulate the reactive power. Low Voltage Ride Through has to be done to ensure the system stability in fault conditions. Fault current has to be limited. In this paper, we propose a control strategy for grid connected solar PV inverter. The system study is done under LVRT condition. The strategy is based on current loop under single axis dq rotating coordinate system. Grid connected PV systems has a three phase inverter fed by DC-DC converter which will take care of maximum power point. In this project, a 100kW PV system is studied. The entire system is simulated and analysed using MATLAB Simulink software

Vertical distribution of aerosols over the east coast of India inferred from airborne LIDAR measurements

The information on altitude distribution of aerosols in the atmosphere is essential in assessing the impact of aerosol warming on thermal structure and stability of the atmosphere. In addition, aerosol altitude distribution is needed to address complex problems such as the radiative interaction of aerosols in the presence of clouds. With this objective, an extensive, multi-institutional and multi-platform field experiment (ICARB-Integrated Campaign for Aerosols, gases and Radiation Budget) was carried out under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP) over continental India and adjoining oceans during March to May 2006. Here, we present airborne LIDAR measurements carried out over the east Coast of the India during the ICARB field campaign. An increase in aerosol extinction (scattering + absorption) was observed from the surface upwards with a maximum around 2 to 4 km. Aerosol extinction at higher atmospheric layers (>2 km) was two to three times larger compared to that of the surface. A large fraction (75-85%) of aerosol column optical depth was contributed by aerosols located above 1 km. The aerosol layer heights (defined in this paper as the height at which the gradient in extinction coefficient changes sign) showed a gradual decrease with an increase in the offshore distance. A large fraction (60-75%) of aerosol was found located above clouds indicating enhanced aerosol absorption above clouds. Our study implies that a detailed statistical evaluation of the temporal frequency and spatial extent of elevated aerosol layers is necessary to assess their significance to the climate. This is feasible using data from space-borne lidars such as CALIPSO, which fly in formation with other satellites like MODIS AQUA and MISR, as part of the A-Train constellation

3-Ethyl-4-methyl-1H-pyrazol-2-ium-5-olate

The title compound, C6H10N2O, is a zwitterionic pyrazole derivative. The crystal packing is predominantly governed by a three-center iminium–amine N+—H⋯O−⋯H—N inter­action, leading to an undulating sheet-like structure lying parallel to (100)

RoLoMa: robust loco-manipulation for quadruped robots with arms

Deployment of robotic systems in the real world requires a certain level of robustness in order to deal with uncertainty factors, such as mismatches in the dynamics model, noise in sensor readings, and communication delays. Some approaches tackle these issues reactively at the control stage. However, regardless of the controller, online motion execution can only be as robust as the system capabilities allow at any given state. This is why it is important to have good motion plans to begin with, where robustness is considered proactively. To this end, we propose a metric (derived from first principles) for representing robustness against external disturbances. We then use this metric within our trajectory optimization framework for solving complex loco-manipulation tasks. Through our experiments, we show that trajectories generated using our approach can resist a greater range of forces originating from any possible direction. By using our method, we can compute trajectories that solve tasks as effectively as before, with the added benefit of being able to counteract stronger disturbances in worst-case scenarios

High pressure studies on YNi<SUB>2</SUB>B<SUB>2</SUB>C and LuNi<SUB>2</SUB>B<SUB>2</SUB>C: ADXRD, thermoelectric power, resistivity, and electronic structure

The electronic and structural behaviour of YNi2B2C and LuNi2B2C at high pressures were investigated by electrical resistivity, thermoelectric power (TEP), and angle dispersive X-ray diffraction measurements and by electronic band structure calculations. The pressure variation of TEP shows a peak around 2 GPa in YNi2B2C. However, the X-ray powder diffraction does not show any structural transition up to 16.4 GPa. The equation of state of YNi2B2C yielded a relatively high bulk modulus of 200 GPa. The observed peak in TEP and the pressure variation of the superconducting transition temperature can be correlated with different components of the electronic density of states. The universal equation of state shows deviation from linearity around 1.5 GPa pressure and correlates well with the TEP peak