We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as ...
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We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO–Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10−15. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.
Although the canbus limits, it stills used in all modern automobiles. Several researches focused on enhancing its reliability and data transfer speed. A combining between switching fabric technology and canprotocol pr...
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Although the canbus limits, it stills used in all modern automobiles. Several researches focused on enhancing its reliability and data transfer speed. A combining between switching fabric technology and canprotocol produced an impressive results. By reflecting on the major performance boost especially on throughput, latency delay and loss probability we can touch the switching fabric contribution. In this paper we will present a new switched fabric can based on broadcast pattern. This latter solution is always a mixture between canprotocol and switched fabric technology where we played on the internal architecture of our previous model. By looking for a fast and reliable hardware solution, we replaced the crossbar pattern by broadcasting one. In fact, this latter is the most suitable pattern for the canprotocol by nature. The second major modification touches scheduler site. In order to obtain an optimized circuit frequency, we used just one scheduler that induce to reduce the integrated circuit area cost. As a result, the latency delay, the loss probability, the throughput, power consumption and clock threshold results show notable enhancing. In this paper, we modeled, implemented and evaluated a broadcasting switched fabric can. The implementation results was obtained by simulated the vhdl design under modelsim tool.
Recently, games have started to be used in the educational field to teach different subjects. In fact, according to different research works, educational games have made learners more motivated and interested in learn...
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Recently, games have started to be used in the educational field to teach different subjects. In fact, according to different research works, educational games have made learners more motivated and interested in learning. At the same time, learning analytics is gaining an increasing attention because it supports evaluating the learner, the given courses and the learning environment. This paper presents a newly designed educational game for teaching computer architecture subject. Learning analytics was used to evaluate the game. The obtained results showed that: (1) The game is efficient in teaching computer architecture subject. (2) Further support for female learners is needed during the learning-playing process. (3) Some of the game learning activities require further design enhancement to be noticeable by learners during the learning-playing process. (4) Further motivational game elements are needed during the learning-playing process.
The combination of personalization parameters for providing personalization of learning scenarios has been an important subject of research in recent years. Several systems have been reported in the literature for ass...
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The combination of personalization parameters for providing personalization of learning scenarios has been an important subject of research in recent years. Several systems have been reported in the literature for assembling the mentioned parameters by reusing existing parameters. However, very little research is available that focuses on optimizing this composition. This work proposes a new approach which allows teachers to choose the optimal composition of personalization parameters by considering the minimal cost of e-learning personalization.
Scientific workflows are used to model applications of high throughput computation and complex large scale data analysis. In recent years, cloudcomputing is fast evolving as the target platform for such applications ...
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Scientific workflows are used to model applications of high throughput computation and complex large scale data analysis. In recent years, cloudcomputing is fast evolving as the target platform for such applications among researchers. Furthermore, new pricing models have been pioneered by cloud providers that allow users to provision resources and to use them in an efficient manner with significant cost reductions. In this paper, we propose a scheduling algorithm that schedules tasks on cloud resources using two different pricing models (spot and on-demand instances) to reduce the cost of execution whilst meeting the workflow deadline. The proposed algorithm is fault tolerant against the premature termination of spot instances and also robust against performance variations of cloud resources. Experimental results demonstrate that our heuristic reduces up to 70% execution cost as against using only on-demand instances.
Architecture,methods and approaches to implementation of the software platform AIS "Signal" *** platform supports various instrumental observation networks of the Far Eastern Branch of Russian Academy of Sci...
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ISBN:
(纸本)9781605952406
Architecture,methods and approaches to implementation of the software platform AIS "Signal" *** platform supports various instrumental observation networks of the Far Eastern Branch of Russian Academy of Sciences and collaboration researches using scientific data collected in the monitoring of hazardous natural processes and phenomena in the territory of the Russian Far East.
We report results from searches for anisotropic stochastic gravitational-wave backgrounds using data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. For the first time, we includ...
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We report results from searches for anisotropic stochastic gravitational-wave backgrounds using data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. For the first time, we include Virgo data in our analysis and run our search with a new efficient pipeline called pystoch on data folded over one sidereal day. We use gravitational-wave radiometry (broadband and narrow band) to produce sky maps of stochastic gravitational-wave backgrounds and to search for gravitational waves from point sources. A spherical harmonic decomposition method is employed to look for gravitational-wave emission from spatially-extended sources. Neither technique found evidence of gravitational-wave signals. Hence we derive 95% confidence-level upper limit sky maps on the gravitational-wave energy flux from broadband point sources, ranging from Fα,Θ<(0.013–7.6)×10−8 erg cm−2 s−1 Hz−1, and on the (normalized) gravitational-wave energy density spectrum from extended sources, ranging from Ωα,Θ<(0.57–9.3)×10−9 sr−1, depending on direction (Θ) and spectral index (α). These limits improve upon previous limits by factors of 2.9–3.5. We also set 95% confidence level upper limits on the frequency-dependent strain amplitudes of quasimonochromatic gravitational waves coming from three interesting targets, Scorpius X-1, SN 1987A and the Galactic Center, with best upper limits range from h0<(1.7–2.1)×10−25, a factor of ≥2.0 improvement compared to previous stochastic radiometer searches.
Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In...
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Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation timescale of DM.
By pulsed s-shell resonant excitation of a single quantum dot-micropillar system, we generate long streams of 1000 near-transform-limited single photons with high mutual indistinguishability. The Hong-Ou-Mandel interf...
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By pulsed s-shell resonant excitation of a single quantum dot-micropillar system, we generate long streams of 1000 near-transform-limited single photons with high mutual indistinguishability. The Hong-Ou-Mandel interference of two photons is measured as a function of their emission time separation varying from 13 ns to 14.7 μs, where the visibility slightly drops from 95.9(2)% to a plateau of 92.1(5)% through a slow dephasing process occurring at a time scale of 0.7 μs. A temporal and spectral analysis reveals the pulsed resonance fluorescence single photons are close to the transform limit, which are readily useful for multiphoton entanglement and interferometry experiments.
We present the results of a search for gravitational-wave transients associated with core-collapse supernova SN 2023ixf, which was observed in the galaxy Messier 101 via optical emission on 2023 May 19, during the LIG...
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