Microcontroller Implementation Of Single Phase Inverter Switching Strategies.

This paper presents the practical microcontroller implementation of single phase inverter switching strategies

Temperature Distribution of Three-Dimensional Photovoltaic Panel by Using Finite Element Simulation

The low electricity performance of a photovoltaic (PV) panel has been concerned in the PV application system. The effect of environmental and operating condition was affected the performance of the PV panel. In this research work, the main objective is to perform a three-dimensional geometry model of monocrystalline silicon PV panel with and without cooling system by using finite element method. In the case of a cooling system, the effect of the Direct Current (DC) fan flow rate on the temperature distribution of PV panel was investigated. The electrical behaviour of this PV panel is obtained based on the average temperature of the PV panel obtained and average solar irradiance from site location. According to the experimental results, PV panel with cooling system can be significant to provide better performance than the PV panel without cooling system in the same environmental condition. For the effect of flow rate of DC fan in the PV panel with cooling system, the performance of this PV panel has been improved as increasing in flow rate of DC fan

Design of Microstrip Bandpass Filter with Defected Microstrip Structure (DMS)

This paper presents a novel design of Chebyshev wideband bandpass filter (BPF) realized using microstrip with Defected Microstrip Structure (DMS) to produce bandpass and band reject characteristics simultaneously. This new class of filter is designed based upon λ_g0/4 short-circuited stubs structure of 7th degree. The filter exhibits wide bandwidth response from 3 to 6 GHz with a return loss, S11, better than - 20 dB and insertion loss, S21, of around -0.1 dB respectively. While, the DMS exhibit a band reject response better than -20 dB at a frequency of 5.2 GHz with a narrow bandwidth. Therefore, the integrated BPF and DMS produce wideband bandpass and band reject response simultaneously in order to remove any undesired signals in the passband of the bandpass response. This design is simulated on a Roger Duroid RO4350 with a dielectric constant,ε_r of 3.48 and a thickness of 0.508 mm. The simulation results show a promising performance that could be further examined during fabrication and experimental works in a laboratory. This type of filter is useful in any RF/ microwave communication systems particularly to eliminate any undesired signals in wideband applications. The reduction of overall physical volume and weight as well as cost and maintaining its excellent performance can also be achieved using this technique

ELECTROMYOGRAPHY ANALYSIS ASSOCIATED WITH PROLONGED STANDING IN METAL STAMPING INDUSTRY

Many jobs in metal stamping industry require workers to perform in standing position. Standing is a practical working position when the workers are lifting heavy products, and pushing or pulling excessive loads because those jobs require a stable position and large degree of freedom. However, if the workers perform the jobs continuously in standing throughout the working hours, they may be experience muscle fatigue. The objective of this study such as to measure the myoelectric levels (μV) exerted by the left and right erector spinae, left and right tibialis anterior. The myoelectric levels in the muscles were measured using surface Electromyography (sEMG). Ten production workers from a metal stamping industry participated as subjects for sEMG measurement. Out of which, five workers from metal stamping process lines and another five from handwork section. The muscle activity of the subjects was measured for 5 hours and 45 minutes of continuous standing during beginning of workday, middle of workday, and end of workday from Monday to Wednesday. Results of comparison found that the two groups of workers show significant difference (p-value < 0.05) in myoelectric level in the right erector spinae, right gastrocnemius, and left tibialis anterior during the beginning of workday. However, the two groups of workers did not show any significant difference in myoelectric level during the middle of the workday and end of the workday. It can be concluded that muscle activity of the workers was determined by the work load and duration of standing. This study suggests that anti fatigue mat and micro breaks should be provided to the workers to reduce muscle fatigue

All-sky search for long-duration gravitational wave transients with initial LIGO

We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

All-sky search for long-duration gravitational wave transients with initial LIGO

We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58×10-8, Ω0V<6.35×10-8, and Ω0S<1.08×10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society

Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available

On the progenitor of binary neutron star merger GW170817

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∼40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∼2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the time of the second supernova (SN). We generate simulated progenitor populations and follow the three-dimensional kinematic evolution from binary neutron star (BNS) birth to the merger time, accounting for pre-SN galactic motion, for considerably different input distributions of the progenitor mass, pre-SN semimajor axis, and SN-kick velocity. Though not considerably tight, we find these constraints to be comparable to those for Galactic BNS progenitors. The derived constraints are very strongly influenced by the requirement of keeping the binary bound after the second SN and having the merger occur relatively close to the center of the galaxy. These constraints are insensitive to the galaxy's star formation history, provided the stellar populations are older than 1 Gyr