Generic bounds on dipolar gravitational radiation from inspiralling compact binaries

Various alternative theories of gravity predict dipolar gravitational radiation in addition to quadrupolar radiation. We show that gravitational wave (GW) observations of inspiralling compact binaries can put interesting constraints on the strengths of the dipole modes of GW polarizations. We put forward a physically motivated gravitational waveform for dipole modes, in the Fourier domain, in terms of two parameters: one which captures the relative amplitude of the dipole mode with respect to the quadrupole mode ($\alpha$) and the other a dipole term in the phase ($\beta$). We then use this two parameter representation to discuss typical bounds on their values using GW measurements. We obtain the expected bounds on the amplitude parameter $\alpha$ and the phase parameter $\beta$ for Advanced LIGO (AdvLIGO) and Einstein Telescope (ET) noise power spectral densities using Fisher information matrix. AdvLIGO and ET may at best bound $\alpha$ to an accuracy of $\sim10^{-2}$ and $\sim10^{-3}$ and $\beta$ to an accuracy of $\sim10^{-5}$ and $\sim10^{-6}$ respectively.Comment: Matches with the published versio

A Low Complex 12-Band Non-uniform FIR Digital Filter Bank Using Frequency Response Masking Technique For Hearing Aid

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Probing the non-linear structure of general relativity with black hole binaries

Observations of the inspiral of massive binary black holes (BBH) in the Laser Interferometer Space Antenna (LISA) and stellar mass binary black holes in the European Gravitational-Wave Observatory (EGO) offer an unique opportunity to test the non-linear structure of general relativity. For a binary composed of two non-spinning black holes, the non-linear general relativistic effects depend only on the masses of the constituents. In a recent letter, we explored the possibility of a test to determine all the post-Newtonian coefficients in the gravitational wave-phasing. However, mutual covariances dilute the effectiveness of such a test. In this paper, we propose a more powerful test in which the various post-Newtonian coefficients in the gravitational wave phasing are systematically measured by treating three of them as independent parameters and demanding their mutual consistency. LISA (EGO) will observe BBH inspirals with a signal-to-noise ratio of more than 1000 (100) and thereby test the self-consistency of each of the nine post-Newtonian coefficients that have so-far been computed, by measuring the lower order coefficients to a relative accuracy of $\sim 10^{-5}$ (respectively, $\sim 10^{-4}$) and the higher order coefficients to a relative accuracy in the range $10^{-4}$-0.1 (respectively, $10^{-3}$-1).Comment: 5 pages, 4 figures. Revised version, accepted for publication in Phys. Rev

Inspiralling compact binaries in quasi-elliptical orbits: The complete third post-Newtonian energy flux

The instantaneous contributions to the 3PN gravitational wave luminosity from the inspiral phase of a binary system of compact objects moving in a quasi elliptical orbit is computed using the multipolar post-Minkowskian wave generation formalism. The necessary inputs for this calculation include the 3PN accurate mass quadrupole moment for general orbits and the mass octupole and current quadrupole moments at 2PN. Using the recently obtained 3PN quasi-Keplerian representation of elliptical orbits the flux is averaged over the binary's orbit. Supplementing this by the important hereditary contributions arising from tails, tails-of-tails and tails squared terms calculated in a previous paper, the complete 3PN energy flux is obtained. The final result presented in this paper would be needed for the construction of ready-to-use templates for binaries moving on non-circular orbits, a plausible class of sources not only for the space based detectors like LISA but also for the ground based ones.Comment: 40 pages. Minor changes in text throughout. Minor typos in Eqs. (3.3b), (7.7f), (8.19d) and (8.20) corrected. Matches the published versio

Guest editorial: Transparency, accountability and the role of control mechanisms during the COVID-19 pandemic: a future research agenda in the context of emerging economies

The rapid spread of the coronavirus (COVID-19) triggered an unprecedented global health crisis. This resulted in governments across the world having to take ‘wartime’ measures in promoting health and safety of their citizens. As a response to the pandemic, governments in different countries, advised by relevant experts, announced countrywide shutdowns, restricting the movement of people, suspending public transportation, and closing most businesses. In many countries, the government also unveiled unprecedented stimulus plans to mitigate the economic impact of the crisis on their citizens. Understandably, due to the nature of the pandemic, much of such public spending had to occur through an expedited process. This, in turn, could potentially create higher risks for corruption and mismanagement (ACCA, 2021). As Transparency International (TI 2020) highlights, extraordinary outbreaks like the COVID19 pandemic also give rise to opportunities for corruption, which might eventually undermine the response to the pandemic. Such corruption can happen in forms, ranging from underreporting of cases to gross irregularities in disbursements of various financial stimulus packages offered by governments

Tail effects in the third post-Newtonian gravitational wave energy flux of compact binaries in quasi-elliptical orbits

The far-zone flux of energy contains hereditary (tail) contributions that depend on the entire past history of the source. Using the multipolar post-Minkowskian wave generation formalism, we propose and implement a semi-analytical method in the frequency domain to compute these contributions from the inspiral phase of a binary system of compact objects moving in quasi-elliptical orbits up to 3PN order. The method explicitly uses the quasi-Keplerian representation of elliptical orbits at 1PN order and exploits the doubly periodic nature of the motion to average the 3PN fluxes over the binary's orbit. Together with the instantaneous (non-tail) contributions evaluated in a companion paper, it provides crucial inputs for the construction of ready-to-use templates for compact binaries moving on quasi-elliptic orbits, an interesting class of sources for the ground based gravitational wave detectors such as LIGO and Virgo as well as space based detectors like LISA.Comment: 32 pages, 10 figures. Minor changes in text throughout. Matches the published versio

Analysis of suitable converter for the implementation of drive system in solar photovoltaic panels

Introduction. Photovoltaic (PV) systems gained immense attraction in the recent years since it produces electricity without causing environmental pollution through direct conversion of solar irradiance into electricity. Solar PV panels produce DC power. The magnitude of this DC power varies with temperature and irradiance of the sun rays. The DC supply from solar panels can be regulated using DC-DC converter and then can further be converted into the desired AC voltage by means of a voltage source inverter before being fed to an induction motor (IM). The speed and torque of an IM, fed from PV arrays, can vary due to the variation in the output power of the panels. Goal of this work is to improve the dynamic performance and reduce the torque ripple of Cuk converter-inverter fed IM drive system. The novelty of the current work proposes interleaved Cuk converter between solar PV DC source and the inverter. Purpose. To provide continuous current using an interleaved Cuk converter to the IM drive and in turn to reduce the torque ripple in IM. Methodology. Introduced an interleaved Cuk converter which is a blend of Cuk converters connected in parallel with each other between solar PV arrays and IM drive system. Originality. Simulation results are obtained for Cuk converter and interleaved Cuk converter fed IM drive by means of MATLAB. The hardware setup for the same IM systems is developed. Practical value. Simulation and hardware results are coincided with each other and it is subject from the simulation and hardware results that the interleaved Cuk converter-inverter fed IM system produced results superior than the Cuk converter inverter fed IM drive system.Вступ. Фотоелектричні (ФЕ) системи набули величезної привабливості в останні роки, оскільки вони виробляють електроенергію, не викликаючи забруднення навколишнього середовища, за рахунок прямого перетворення сонячного випромінювання на електрику. Сонячні ФЕ панелі виробляють енергію постійного струму. Значення цієї потужності постійного струму залежить від температури та освітленості сонячних променів. Подача постійного струму від сонячних панелей може регулюватися за допомогою DC-DC перетворювача, а потім може бути перетворена в бажану змінну напругу за допомогою інвертора джерела напруги перед подачею на асинхронний двигун. Швидкість та обертаючий момент асинхронного двигуна, що живиться від ФЕ батарей, можуть змінюватися через зміну вихідної потужності панелей. Метою даної роботи є покращення динамічних характеристик та зменшення пульсацій обертаючого моменту системи приводу асинхронного двигуна з живленням від Cuk перетворювача-інвертора. Новизна цієї роботи пропонує Cuk перетворювач, що чергується, між сонячним ФЕ джерелом постійного струму та інвертором. Мета. Забезпечення безперервності струму за допомогою Cuk перетворювача, що чергується, для приводу асинхронного двигуна і, у свою чергу, зменшення пульсації обертаючого моменту в асинхронному двигуні. Методологія. Представлений Cuk перетворювач, що чергується, який являє собою суміш Cuk перетворювачів, підключених паралельно один до одного між сонячними ФЕ батареями і системою приводу асинхронного двигуна. Оригінальність. Результати моделювання отримані для Cuk перетворювача і приводу асинхронного двигуна з живленням Cuk перетворювача, що чергується, за допомогою MATLAB. Розроблено апаратну частину цих же асинхронних двигунів. Практична цінність. Результати моделювання та апаратного забезпечення збігаються один з одним, і з результатів моделювання та апаратного забезпечення випливає, що система асинхронного двигуна з живленням від Cuk перетворювача-інвертора, що чергується, дає результати, які перевищують результати, ніж система приводу асинхронного двигуна з живленням від Cuk перетворювача

Design and Development of an Efficient Branch Predictor for an In-order RISC-V Processor

Conditional branches are a serious issue in the pipelined processor. The branch direction and branch target address are determined and calculated by the processor after several cycles of the instruction decode, which results in the pipeline stall. Pipeline stall leads to control hazards in the processor and results in performance degradation. To increase the rate of the instruction flow in modern processors, branch prediction is used. Branch prediction provides an ideal speedup in performance of the processor. The processor predicts the direction in the branch prediction and determines instructions in accordance with the predicted path. The processor tests any prediction for the branch when the branch condition is calculated. If the prediction is incorrect, the processor will automatically abort all instructions taken along the wrong path and return the state to the address of the determined branch. An inaccurate branch predictor results in increased program run-time and leads to higher power consumption. Once the position of a branch is known, the actual target address of the next instruction must also be determined along the expected path. If the branch is expected not to be taken, the destination address is simply the address of the current branch plus the size of the command word. Unless the branch is to be taken, then the target depends on the branch type. The branch target buffer (BTB) can reduce branch efficiency by predicting the branch path and storing information used by branch. There are no stalls if the branch entry is found in BTB, and the calculation is accurate, or the penalty shall be two cycles or more. This paper focuses on the design and development of branch predictor with BTB for the fetch unit, which further integrates to an in-order pipelined RISC-V processor. The performance of the RISC-V core in terms of clock cycle latency, instruction per cycle (IPC), was measured and analyzed

Parametrized tests of post-Newtonian theory using Advanced LIGO and Einstein Telescope

General relativity has very specific predictions for the gravitational waveforms from inspiralling compact binaries obtained using the post-Newtonian (PN) approximation. We investigate the extent to which the measurement of the PN coefficients, possible with the second generation gravitationalwave detectors such as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and the third generation gravitational-wave detectors such as the Einstein Telescope (ET), could be used to test post-Newtonian theory and to put bounds on a subclass of parametrized-post-Einstein theories which differ from general relativity in a parametrized sense. We demonstrate this possibility by employing the best inspiralling waveform model for nonspinning compact binaries which is 3.5PN accurate in phase and 3PN in amplitude. Within the class of theories considered, Advanced LIGO can test the theory at 1.5PN and thus the leading tail term. Future observations of stellar mass black hole binaries by ET can test the consistency between the various PN coefficients in the gravitational-wave phasing over the mass range of 11-44 Msun. The choice of the lower frequency cut off is important for testing post-Newtonian theory using the ET. The bias in the test arising from the assumption of nonspinning binaries is indicated.Comment: 18 pages, 11 figures, Matches with the published versio