Статті в журналах: "Point source search"

1

LE COULTRE, P. "SEARCH FOR BURST SIGNALS FROM POINT SOURCES." International Journal of Modern Physics A 20, no. 29 (November 20, 2005): 6962–64. http://dx.doi.org/10.1142/s0217751x05030600.

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A sky survey for flaring point sources emitting high energy gamma rays has been performed with the L 3+ C underground muon spectrometer at LEP, CERN. Data were collected from mid July to October 1999 and from April to November 2000. No signal excesses in any direction have been found with muons above 20, 30, 50 and 100 GeV within one day and longer time windows. The steady muon flux sensitivity is of the order of a few times 10-9 cm-2 s-1 for muon energies above 20 GeV, and between 2 × 10-11 and 5 × 10-10 cm -2 s -1 for muon energies above 20 GeV depending on the source position.

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2

Chen, X., and E. L. Wright. "Extragalactic Point‐Source Search inWMAP61 and 94 GHz Data." Astrophysical Journal 681, no. 2 (July 10, 2008): 747–55. http://dx.doi.org/10.1086/588249.

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3

Mangano, S. "Astrophysical point source search with the ANTARES neutrino telescope." Nuclear Physics B - Proceedings Supplements 229-232 (August 2012): 548. http://dx.doi.org/10.1016/j.nuclphysbps.2012.09.185.

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4

Michael, Tino. "All flavour point-source search with the ANTARES neutrino telescope." Journal of Physics: Conference Series 888 (September 2017): 012103. http://dx.doi.org/10.1088/1742-6596/888/1/012103.

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5

Biller, S., D. E. Alexandreas, G. E. Allen, D. Berley, R. L. Burman, M. Cavalli-Sforza, C. Y. Chang, et al. "Search for Ultra--High-Energy Point-Source Emission over Various Timescales." Astrophysical Journal 423 (March 1994): 714. http://dx.doi.org/10.1086/173850.

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6

Alexandreas, D. E., D. Berley, S. Biller, G. M. Dion, J. A. Goodman, T. J. Haines, C. M. Hoffman, et al. "Point source search techniques in ultra high energy gamma ray astronomy." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 328, no. 3 (May 1993): 570–77. http://dx.doi.org/10.1016/0168-9002(93)90677-a.

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7

Braun, Jim, Mike Baker, Jon Dumm, Chad Finley, Albrecht Karle, and Teresa Montaruli. "Time-dependent point source search methods in high energy neutrino astronomy." Astroparticle Physics 33, no. 3 (April 2010): 175–81. http://dx.doi.org/10.1016/j.astropartphys.2010.01.005.

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8

W. Masheder, M. R., R. J. Cohen, and N. L. Martin-Hernandez. "OH masers associated with IRAS point sources." Symposium - International Astronomical Union 206 (2002): 116–19. http://dx.doi.org/10.1017/s0074180900222195.

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We report a search for masers from the A-doublet of the ground-state of OH at 18cm, carried out with the Jodrell Bank Lovell Telescope and with the 25m Dwingeloo telescope. All objects north of δ = −20° which appear in the IRAS Point Source Catalog with fluxes > 1000 Jy at 60μm and 100μm were observed in all four lines and both circular polarisations over the required velocity range. Preliminary results of 52 maser sources are reported here.

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9

Bellenghi, C., T. Glauch, C. Haack, T. Kontrimas, H. Niederhausen, R. Reimann, and M. Wolf. "A new and improved IceCube point source analysis." Journal of Instrumentation 16, no. 11 (November 1, 2021): C11002. http://dx.doi.org/10.1088/1748-0221/16/11/c11002.

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Abstract The IceCube Neutrino Observatory, a cubic kilometer scale Cherenkov detector deployed in the deep ice at the geographic South Pole, investigates extreme astrophysical phenomena by studying the corresponding high-energy neutrino signal. Its discovery of a diffuse flux of astrophysical neutrinos with energies up to the PeV scale in 2013 has triggered a vast effort to identify the mostly unknown sources of these high energy neutrinos. Here, we present a new IceCube point-source search that improves the accuracy of the statistical analysis, especially at energies of a few TeV and below. The new approach is based on multidimensional kernel density estimation for the probability density functions and new estimators for the observables, namely the reconstructed energy and the estimated angular uncertainty on the reconstructed arrival direction. The more accurate analysis provides an improvement in discovery potential up to ∼30% over previous works for hard spectrum sources.

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10

Chen, X., and E. L. Wright. "EXTRAGALACTIC POINT SOURCE SEARCH IN FIVE-YEARWMAP41, 61, AND 94 GHz MAPS." Astrophysical Journal 694, no. 1 (March 14, 2009): 222–34. http://dx.doi.org/10.1088/0004-637x/694/1/222.

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11

Masuyama, Hiroyuki, and Koichi Mizutani. "Search for Reflection Point Utilizing Reflected Wave Using Single Rectangular Sound Source." Japanese Journal of Applied Physics 46, no. 12 (December 6, 2007): 7793–97. http://dx.doi.org/10.1143/jjap.46.7793.

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12

Alam, Afroz, Preeti Verma, Mohd Tariq, Adil Sarwar, Basem Alamri, Noore Zahra, and Shabana Urooj. "Jellyfish Search Optimization Algorithm for MPP Tracking of PV System." Sustainability 13, no. 21 (October 24, 2021): 11736. http://dx.doi.org/10.3390/su132111736.

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Because of the rapid increase in the depletion rate of conventional energy sources, the energy crisis has become a central problem in the contemporary world. This issue opens the gateway for exploring and developing renewable energy sources to fulfill the exigent energy demand. Solar energy is an abundant source of sustainable energy and hence, nowadays, solar photovoltaic (PV) systems are employed to extract energy from solar irradiation. However, the PV systems need to work at the maximum power point (MPP) to exploit the highest accessible power during varying operating conditions. For this reason, maximum power point tracking (MPPT) algorithms are used to track the optimum power point. Furthermore, the efficient utilization of PV systems is hindered by renowned partial shading conditions (PSC), which generate multiple peaks in the power-voltage characteristic of the PV array. Thus, this article addresses the performance of the newly developed jellyfish search optimization (JSO) strategy in the PV frameworks to follow the global maximum power point (GMPP) under PSC.

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13

Chaiwino, Wipawinee, Panasun Manorot, Kanyuta Poochinapan, and Thanasak Mouktonglang. "Identifying the Locations of Atmospheric Pollution Point Source by Using a Hybrid Particle Swarm Optimization." Symmetry 13, no. 6 (June 1, 2021): 985. http://dx.doi.org/10.3390/sym13060985.

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This research aims to improve the particle swarm optimization (PSO) algorithm by combining a multidimensional search with a line search to determine the location of the air pollution point sources and their respective emission rates. Both multidimensional search and line search do not require the derivative of the cost function. By exploring a symmetric property of search domain, this innovative search tool incorporating a multidimensional search and line search in the PSO is referred to as the hybrid PSO (HPSO). Measuring the pollutant concentration emanating from the pollution point sources through the aid of sensors represents the first stage in the process of evaluating the efficiency of HPSO. The summation of the square of the differences between the observed concentration and the concentration that is theoretically expected (inverse Gaussian plume model or numerical estimations) is used as a cost function. All experiments in this research are therefore conducted using the HPSO sensing technique. To effectively identify air pollution point sources as well as calculate emission rates, optimum positioning of sensors must also be determined. Moreover, the frame of discussion of this research also involves a detailed comparison of the results obtained by the PSO algorithm, the GA (genetic algorithm) and the HPSO algorithm in terms of single pollutant location detection, respectively. In the case of multiple sources, only the findings based on PSO and HPSO algorithms are taken into consideration. This research eventually verifies and confirms that the HPSO does offer substantially better performance in the measuring of pollutant locations as well as emission rates of the air pollution point sources than the original PSO.

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14

Mukherjee, R., J. P. Halpern, E. V. Gotthelf, M. Eracleous, and N. Mirabal. "Search for a Point‐Source Counterpart of the Unidentified Gamma‐Ray Source TeV J2032+4130 in Cygnus." Astrophysical Journal 589, no. 1 (May 20, 2003): 487–94. http://dx.doi.org/10.1086/374641.

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15

Abbasi, R. U., M. Abe, T. Abu-Zayyad, M. Allen, R. Azuma, E. Barcikowski, J. W. Belz, et al. "Search for point sources of ultra-high-energy photons with the Telescope Array surface detector." Monthly Notices of the Royal Astronomical Society 492, no. 3 (February 3, 2020): 3984–93. http://dx.doi.org/10.1093/mnras/stz3618.

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ABSTRACT The surface detector (SD) of the Telescope Array (TA) experiment allows us to detect indirectly photons with energies of the order of 1018 eV and higher, and to separate photons from the cosmic ray background. In this paper, we present the results of a blind search for point sources of ultra-high-energy (UHE) photons in the Northern sky using the TA SD data. The photon-induced extensive air showers are separated from the hadron-induced extensive air shower background by means of a multivariate classifier based upon 16 parameters that characterize the air shower events. No significant evidence for the photon point sources is found. The upper limits are set on the flux of photons from each particular direction in the sky within the TA field of view, according to the experiment’s angular resolution for photons. The average 95 per cent confidence level upper-limits for the point-source flux of photons with energies greater than 1018, 1018.5, 1019, 1019.5 and 1020 eV are 0.094, 0.029, 0.010, 0.0073 and 0.0058 km−2yr−1, respectively. For energies higher than 1018.5 eV, the photon point-source limits are set for the first time. Numerical results for each given direction in each energy range are provided as a supplement to this paper.

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16

Gregorio-Hetem, J., J. R. D. Lepine, G. R. Quast, C. A. O. Torres, and R. de La Reza. "A search for T Tauri stars based on the IRAS point source catalog." Astronomical Journal 103 (February 1992): 549. http://dx.doi.org/10.1086/116082.

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17

Torres, C. A. O., G. Quast, R. de La Reza, J. Gregorio-Hetem, and J. R. D. Lepine. "Search for T Tauri Stars Based on the IRAS Point Source Catalog. II." Astronomical Journal 109 (May 1995): 2146. http://dx.doi.org/10.1086/117440.

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18

Резник, Александр Львович, and Александр Анатольевич Соловьев. "Time-optimal algorithms for detecting and localizing for a random point-pulse source with a unimodal distribution density." Вычислительные технологии, no. 3 (July 21, 2022): 36–45. http://dx.doi.org/10.25743/ict.2022.27.3.004.

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Сформулирована задача построения оптимального по времени алгоритма поиска с заданной точностью случайного импульсного источника, имеющего одномодальную ступенчатую плотность распределения на интервале поиска. Локализация сигнального источника, обнаруживающего себя в случайные моменты времени генерацией мгновенных импульсов, осуществляется с помощью детекторного приемника с динамически программируемым размером сканирующей апертуры. При разработке оптимальных поисковых алгоритмов основная трудность вызвана необходимостью нахождения точного решения вариационной задачи, связанной с минимизацией многомерного линейного функционала, описывающего среднее (по ансамблю реализаций) время поиска неизвестного точечно-импульсного источника. Показано, что при одномодальной ступенчатой плотности распределения разыскиваемого источника возможно построение оптимальных физически реализуемых алгоритмов поиска с использованием односвязной апертуры детекторного приемника The issues of constructing high-speed algorithms for searching of pulsed-point sources are considered. A pulsed-point source is treated as an object of negligible angular dimensions (mathematical point). It is supposed having a random distribution density over the search interval; it randomly generates infinitely short impulses (delta functions) Pauses between impulses have an exponential distribution density. Detection and localization of such sources is carried out by a system that includes a receiver with a programmable and arbitrarily time-tunable view window. When the incoming pulse is detected, the position of the searched source is refined and the receiver’s view window decreases; at the next stage, the search continues inside the window where the impulse was fixed. In majority of scientific and technical applications, minimizing the time of detection and localization of random pulsed-point sources requires solving time-consuming variational problems associated with finding extremals of complex integral functionals in the presence of restrictions. As a result, the exact analytical solution of the problem (if it is principally achievable), as a rule, cannot be physically implemented in the form of a scheme with continuous movement of a simply connected scanning window of the receiver. In this paper, we have shown that in the case when the distribution density of a random point source can be represented as an unimodal step function, it is possible to construct a time-optimal and physically realizable strategy for its localization. Algorithms for the localization of random pulsed-point sources that have a multistage single- modal probability distribution density over the search interval and reveal themselves by generating instantaneous impulses at random times are proposed. The parameters of the optimal algorithm are calculated that minimizes the average (in statistical terms, i.e., according to implementation ensemble) the search time for a random source depending on the a priori density of its distribution, the power of the source, and the required localization accuracy.

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19

BIGONGIARI, C. "SEARCH FOR NEUTRINO EMISSION FROM GAMMA-RAY SOURCES WITH THE ANTARES TELESCOPE." International Journal of Modern Physics: Conference Series 08 (January 2012): 307–10. http://dx.doi.org/10.1142/s201019451200476x.

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ANTARES is the first undersea neutrino detector ever built and presently the neutrino telescope with the largest effective area operating in the Northern Hemisphere. A three-dimensional array of photomultiplier tubes detects the Cherenkov light induced by the muons produced in the interaction of high energy neutrinos with the matter surrounding the detector. The detection of astronomical neutrino sources is one of the main goals of ANTARES. The search for point-like neutrino sources with the ANTARES telescope is described and the preliminary results obtained with data collected from 2007 to 2010 are shown. No cosmic neutrino source has been observed and neutrino flux upper limits have been calculated for the most promising source candidates.

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20

Wang, Zheng, and Shian-Shyong Tseng. "Knee Point Search Using Cascading Top-kSorting with Minimized Time Complexity." Scientific World Journal 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/960348.

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Anomaly detection systems and many other applications are frequently confronted with the problem of finding the largest knee point in the sorted curve for a set of unsorted points. This paper proposes an efficient knee point search algorithm with minimized time complexity using the cascading top-ksorting when a priori probability distribution of the knee point is known. First, a top-ksort algorithm is proposed based on a quicksort variation. We divide the knee point search problem into multiple steps. And in each step an optimization problem of the selection numberkis solved, where the objective function is defined as the expected time cost. Because the expected time cost in one step is dependent on that of the afterwards steps, we simplify the optimization problem by minimizing the maximum expected time cost. The posterior probability of the largest knee point distribution and the other parameters are updated before solving the optimization problem in each step. An example of source detection of DNS DoS flooding attacks is provided to illustrate the applications of the proposed algorithm.

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21

Rowan-Robinson, Michael. "A search for Planet 9 in the IRAS data." Monthly Notices of the Royal Astronomical Society 510, no. 3 (November 15, 2021): 3716–26. http://dx.doi.org/10.1093/mnras/stab3212.

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ABSTRACT I have carried out a search for Planet 9 in the IRAS data. At the distance range proposed for Planet 9, the signature would be a 60 $\mu$m unidentified IRAS point source with an associated nearby source from the IRAS reject file of sources which received only a single hours-confirmed (HCON) detection. The confirmed source should be detected on the first two HCON passes, but not on the third, while the single HCON should be detected only on the third HCON. I have examined the unidentified sources in three IRAS 60 $\mu$m catalogs: some can be identified with 2MASS galaxies, Galactic sources or as cirrus. The remaining unidentified sources have been examined with the IRSA Scanpi tool to check for the signature missing HCONs, and for association with IRAS reject file single HCONs. No matches of interest survive. For a lower mass planet (≤5ME) in the distance range 200–400 AU, we expect a pair or triplet of single HCONs with separations 2–35 arcmin. Several hundred candidate associations are found and have been examined with Scanpi. A single candidate for Planet 9 survives which satisfies the requirements for detected and non-detected HCON passes. A fitted orbit suggest a distance of 225 ± 15 AU and a mass of 3–5 ME. Dynamical simulations are needed to explore whether the candidate is consistent with existing planet ephemerides. If so, a search in an annulus of radius 2.5–4° centred on the 1983 position at visible and near-infrared wavelengths would be worthwhile.

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22

Straal, S. M., and J. van Leeuwen. "A LOFAR search for steep-spectrum pulsars in supernova remnants and pulsar wind nebulae." Astronomy & Astrophysics 623 (March 2019): A90. http://dx.doi.org/10.1051/0004-6361/201833922.

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Pinpointing a pulsar in its parent supernova remnant (SNR) or resulting pulsar wind nebula (PWN) is key to understanding its formation history and the pulsar wind mechanism, yet only about half the SNRs and PWNe appear associated with a pulsar. Our aim was to find the pulsars in a sample of eight known and new SNRs and PWNe. Using the LOFAR radio telescope at 150 MHz, each source was observed for 3 h. We covered the entire remnants where needed, by employing many tied-array beams to tile out even the largest objects. For objects with a confirmed point source or PWN we constrained our search to those lines of sight. We identified a promising radio pulsar candidate towards PWN G141.2+5.0. The candidate, PSR J0337+61, has a period of 94 ms and a DM of 226 pc cm−3. We re-observed the source twice with increased sensitivities of 30% and 50%, but did not re-detect it. It thus remains unconfirmed. For our other sources we obtain very stringent upper limits of 0.8 − 3.1 mJy at 150 MHz. Generally, we can rule out that the pulsars travelled out of the remnant. From these strict limits we conclude our non-detections towards point sources and PWNe are the result of beaming and propagation effects. Some of the remaining SNRs should host a black hole rather than a neutron star.

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23

Wang, Shuopeng, Peng Yang, and Hao Sun. "Sound Source Localization Indoors Based on Two-Level Reference Points Matching." Applied Sciences 12, no. 19 (October 3, 2022): 9956. http://dx.doi.org/10.3390/app12199956.

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A dense sample point layout is the conventional approach to ensure the positioning accuracy for fingerprint-based sound source localization (SSL) indoors. However, mass reference point (RPs) matching of online phases may greatly reduce positioning efficiency. In response to this compelling problem, a two-level matching strategy is adopted to shrink the adjacent RPs searching scope. In the first-level matching process, two different methods are adopted to shrink the search scope of the online phase in a simple scene and a complex scene. According to the global range of high similarity between adjacent samples in a simple scene, a greedy search method is adopted for fast searching of the sub-database that contains the adjacent RPs. Simultaneously, in accordance with the specific local areas’ range of high similarity between adjacent samples in a complex scene, the clustering method is used for database partitioning, and the RPs search scope can be compressed by sub-database matching. Experimental results show that the two-level RPs matching strategy can effectively improve the RPs matching efficiency for the two different typical indoor scenes on the premise of ensuring the positioning accuracy.

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24

Kun, Emma, Imre Bartos, Julia Becker Tjus, Peter L. Biermann, Anna Franckowiak, and Francis Halzen. "Multiwavelength Search for the Origin of IceCube's Neutrinos." Astrophysical Journal 934, no. 2 (August 1, 2022): 180. http://dx.doi.org/10.3847/1538-4357/ac7f3a.

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Abstract The origin of astrophysical high-energy neutrinos detected by the IceCube Neutrino Observatory remains a mystery to be solved. In this paper we search for neutrino source candidates within the 90% containment area of 70 track-type neutrino events recorded by the IceCube Neutrino Observatory. By employing the Fermi-LAT 4FGL-DR2, the Swift-XRT 2SXPS, and the CRATES catalogs, we identify possible gamma-ray, X-ray, and flat-spectrum radio candidate sources of track-type neutrinos. We find that based on the brightness of sources and their spatial correlation with the track-type IceCube neutrinos, the constructed neutrino samples represent special populations of sources taken from the full Fermi-LAT 4FGL-DR2/Swift-XRT 2SXPS/CRATES catalogs with similar significance (2.1σ, 1.2σ, 2σ at 4.8 GHz, 2.1σ at 8.4 GHz, respectively, assuming 50% astrophysical signalness). After collecting redshifts and deriving subsamples of the CRATES catalog complete in the redshift–luminosity plane, we find that the 4.8 GHz (8.4 GHz) subsample can explain between 4% and 53% (3% and 42%) of the neutrinos (90% C.L.), when the probability of detecting a neutrino is proportional to the (k-corrected) radio flux. The overfluctuations indicate that a part of the sample is likely to contribute and that more sophisticated schemes in the source catalog selection are necessary to identify the neutrino sources at the 5σ level. Our selection serves as a starting point to further select the correct sources.

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25

Kaplan, D. L., S. R. Kulkarni, and S. S. Murray. "Search for a Near‐Infrared Counterpart to the Cassiopeia A X‐Ray Point Source." Astrophysical Journal 558, no. 1 (September 2001): 270–75. http://dx.doi.org/10.1086/322459.

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26

Li, Xueyan. "Path planning of intelligent mobile robot based on Dijkstra algorithm." Journal of Physics: Conference Series 2083, no. 4 (November 1, 2021): 042034. http://dx.doi.org/10.1088/1742-6596/2083/4/042034.

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Abstract Under the premise of grid environment modeling method, a relaxed Dijkstra algorithm is proposed to solve the problem of real-time path planning for mobile robot in large-scale and obstacle intensive working environment. Firstly, four neighborhood search is used to construct the Manhattan distance potential field from the source point to the global point in linear time, and then eight neighborhood search is performed from the target point to the source point to return a collision free and approximately optimal path. Matlab simulation results show that the algorithm is 10 times faster than dijksta algorithm and A-star algorithm, and the error of path length is within a reasonable range compared with the shortest path.

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27

Shayne, Mette. "Computerized datasearching for the African scholar." African Research & Documentation 43 (1987): 8–15. http://dx.doi.org/10.1017/s0305862x00010323.

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This article will give some insight into problems and advantages of computerized literature searches for the African scholar. I should point out that there are two types of databases, the reference databases which point users to another source, i.e., give the user bibliographic information. Those are the ones I will deal with here. The source databases contain original information or manipulated statistics prepared for specific purposes. I intend to point out areas where a computerized literature search is useful, and areas where there are pitfalls. My experience is that graduate students rarely are familiar with the bibliographic or data sources available to them.Two different methodologies have been described in the professional literature oh determining the value of certain databases.

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28

Reznik, A. L., A. V. Tuzikov, A. A. Soloviev, A. V. Torgov, and V. A. Kovalev. "Time-optimal algorithms focused on the search for random pulsed-point sources." Computer Optics 43, no. 4 (August 2019): 605–10. http://dx.doi.org/10.18287/2412-6179-2019-43-4-605-610.

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The article describes methods and algorithms related to the analysis of dynamically changing discrete random fields. Time-optimal strategies for the localization of pulsed-point sources having a random spatial distribution and indicating themselves by generating instant delta pulses at random times are proposed. An optimal strategy is a procedure that has a minimum (statistically) average localization time. The search is performed in accordance with the requirements for localization accuracy and is carried out by a system with one or several receiving devices. Along with the predetermined accuracy of localization of a random pulsed-point source, a significant complicating factor of the formulated problem is that the choice of the optimal search procedure is not limited to one-step algorithms that end at the moment of first pulse generation. Moreover, the article shows that even with relatively low requirements for localization accuracy, the time-optimal procedure consists of several steps, and the transition from one step to another occurs at the time of registration of the next pulse by the receiving system. In this case, the situation is acceptable when during the process of optimal search some of the generated pulses are not fixed by the receiving system. The parameters of the optimal search depending on the number of receiving devices and the required accuracy of localization are calculated and described in the paper.

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29

Hartzell, Stephen, and Pengcheng Liu. "Determination of earthquake source parameters using a hybrid global search algorithm." Bulletin of the Seismological Society of America 85, no. 2 (April 1, 1995): 516–24. http://dx.doi.org/10.1785/bssa0850020516.

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Abstract A hybrid global optimization algorithm using a combination of simulated annealing and downhill simplex methods is used to invert teleseismic body waves for earthquake source parameters. Time-domain constraints on the source-time function, inversion for double-couple parameters rather than moment tensor elements, and consideration of multiple sources lead to a nonlinear and multimodal problem, in which the objective function contains many local minima. Traditional approaches that linearize the problem and use iterative least squares are dependent on the starting model and the order in which multiple sources are processed, and can converge to a local minimum. Also, grid searches are impractical for the number of parameters we treat simultaneously. The hybrid global method provides an attractive alternative because it converges to the global minimum of a prescribed objective function and can be used to invert for multiple sources simultaneously. Model parameter constraints are easy to incorporate into the global search process, if they are desired. A multiple point-source parameterization of the 1992 Landers, California, earthquake is used as an example of the inversion method. Rupture in this earthquake occurred along three main fault segments: the Johnson Valley fault, the Homestead fault, and the Emerson/Rock Creek faults. We invert for the strike, dip, and rake of each source, the time separation of the sources, and the farfield source-time function of each source. Parameters obtained from the inversion are consistent with field observations and the results of other investigations. Strikes vary consistently with the trend of the surface ruptures. The dip is near 90° along the entire length of the rupture, and the rake is nearly pure right-lateral strike slip. The estimated moment is 7.6 × 1026 dyne-cm. The continuity of the moment release across the junction of the Homestead and Emerson faults suggests that these two faults may be more continuous at depth than at the surface. Moment release in the transition from the Johnson Valley to the Homestead faults is complex, indicating a complicated time history of faulting and a less direct relationship between the primary mapped faults.

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30

Smith, Russell J. "Discovering novae in early-type galaxies with MUSE: A chance find in NGC 1404, and 12 more candidates from an archival search." Monthly Notices of the Royal Astronomical Society: Letters 494, no. 1 (February 7, 2020): L1—L5. http://dx.doi.org/10.1093/mnrasl/slaa023.

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ABSTRACT I report the discovery of a transient broad-Hα point source in the outskirts of the giant elliptical galaxy NGC 1404, discovered in archival observations taken with the Multi-Unit Spectroscopic Explorer (MUSE) integral field spectrograph. The Hα line width of 1950 km s−1 full width at half-maximum, and luminosity of (4.1 ± 0.1) × 1036 erg s−1, are consistent with a nova outburst, and the source is not visible in MUSE data obtained 9 months later. A transient soft X-ray source was detected at the same position (within <1 arcsec), 14 yr before the Hα transient. If the X-ray and Hα emission are from the same object, the source may be a short-time-scale recurrent nova with a massive white dwarf accretor, and hence a possible Type-Ia supernova progenitor. Selecting broad-Hα point sources in MUSE archival observations for a set of nearby early-type galaxies, I discovered 12 more nova candidates with similar properties to the NGC 1404 source, including five in NGC 1380 and four in NGC 4365. Multi-epoch data are available for four of these twelve sources; all four are confirmed to be transient on ∼1 yr time-scales, supporting their identification as novae.

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31

Setia Gunawan, Diah Y. A., Karel A. van der Hucht, A. Ger de Bruyn, and Peredur M. Williams. "WSRT 21-cm continuum field in Cygnus OB2: in search of more Wolf-Rayet stars." Symposium - International Astronomical Union 193 (1999): 103–4. http://dx.doi.org/10.1017/s0074180900205159.

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We present a deep look into the Cygnus OB2 region using the WSRT. A 2° x 2° map of the optically highly-obscured region was obtained at 1400 MHz, with a noise level down to 0.2 mJy and an angular resolution of 1″. We will compare the resulting radio point source list with optical and near-IR catalogues, in order to identify stellar wind sources like WR and OB stars.

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32

Akram, Saima, Linta Khalil, M. Kamran Liaquat Bhatti, Tayab Aftab, Rabbia Siddique, and Mughees Riaz. "Maximum Power Point Tracking using Direct Control with Cuckoo Search for Photovoltaic Module under Partial Shading Condition." Pakistan Journal of Engineering and Technology 4, no. 2 (June 5, 2021): 28–31. http://dx.doi.org/10.51846/vol4iss2pp28-31.

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In these days, our country Pakistan is facing numerous crises. Electric power is one of them. Therefore, it is time to presents such sources to beat the crises of power. Sources should be like which do not upset the atmosphere. In most of the methods, CO2 generated that spoil the nature solar energy is becoming vital source of renewable energy resources. As such, it is very essential that those in engineering fields be aware of the technologies related with this area. Many cities are built totally with plan of executing Solar technology and this is one of the renewable resources has multiplied across loads areas. Still, it is behind in the track of being a leading energy resource. This work proposes direct control for MPP for photovoltaic module using cuckoo search under partly covered state. It is accredited that artificial intelligence Cuckoo search algorithm shows several merits like fast convergence and higher efficiency using fewer tuning parameters. To justify direct control using CS as a viable MPPT option, a brief analysis is accomplished against two different algorithms, Direct Control and Cuckoo Search algorithm. The ability of the algorithm is to handle the partial shading condition is verified.

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33

Bukartas, Antanas, Jonas Wallin, Robert Finck, and Christopher Rääf. "Accuracy of a Bayesian technique to estimate position and activity of orphan gamma-ray sources by mobile gamma spectrometry: Influence of imprecisions in positioning systems and computational approximations." PLOS ONE 17, no. 6 (June 22, 2022): e0268556. http://dx.doi.org/10.1371/journal.pone.0268556.

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The purpose of this study was to investigate the effects of experimental data on performance of a developed Bayesian algorithm tailored for orphan source search, estimating which parameters affect the accuracy of the algorithm. The algorithm can estimate the position and activity of a gamma-ray point source from experimental mobile gamma spectrometry data. Bayesian estimates were made for source position and activity using mobile gamma spectrometry data obtained from one 123% HPGe detector and two 4-l NaI(Tl) detectors, considering angular variations in counting efficiency for each detector. The data were obtained while driving at 50 km/h speed past the sources using 1 s acquisition interval in the detectors. It was found that deviations in the recorded coordinates of the measurements can potentially increase the uncertainty in the position of the source 2 to 3 times and slightly decrease the activity estimations by about 7%. Due to the various sources of uncertainty affecting the experimental data, the maximum predicted relative deviations of the activity and position of the source remained about 30% regardless of the signal-to-noise ratio of the data. It was also found for the used vehicle speed of 50 km/h and 1 s acquisition time, that if the distance to the source is greater than the distance travelled by the detector during the acquisition time, it is possible to use point approximations of the count-rate function in the Bayesian likelihood with minimal deviations from the integrated estimates of the count-rate function. This approximation reduces the computational demands of the algorithm increasing the potential for applying this method in real-time orphan source search missions.

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34

Cohen, Martin. "An IRAS-based search for new dusty WCL Wolf-Rayet stars." Symposium - International Astronomical Union 163 (1995): 359–62. http://dx.doi.org/10.1017/s0074180900202301.

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I have examined all InfraRed Astronomy Satellite (IRAS) data relevant to the 173 galactic Wolf-Rayet (WR) stars in an updated catalogue provided by van der Hucht (priv. comm.), including the 13 stars newly discovered by Shara et al. (1991). Using the exact coordinates given in these lists, I have examined the IRAS Point Source Catalog (PSC), the Faint Source Catalog, Faint Source Reject Catalog, and generated 1-dimensional spatial profiles (“ADDSCAN”s), and 2-dimensional full-resolution images (“FRESCO”s). The goal was to assemble the best set of observed IRAS colour indices for different WR types, in particular for known dusty WCL objects. These colour indices define zones in the IRAS colour-colour plane. By searching the PSC for otherwise unassociated sources that satisfy these colours, I have identified potential new WR candidates, too faint to have been recognized in previous optical searches. I have extracted these candidates' IRAS Low Resolution Spectrometer (LRS) data and compared the spectra with the highly characteristic LRS shape for known dusty WCL stars. Any surviving candidates must now be examined by optical spectroscopy. This work represents a much more rigorous and exhaustive version of the LRS study that identified IRAS 17380-3031 (WR98a) as the first new WR (WC9) star discovered by IRAS (Cohen et al. 1991).

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35

Wu, Tao, Zhenghong Deng, Jiwei Xu, and Qingyue Gu. "Estimation for Two-Dimensional Incoherently Distributed Source in Double L-Shape Arrays." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, no. 4 (August 2019): 838–45. http://dx.doi.org/10.1051/jnwpu/20193740838.

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Distributed sources can be regarded as an assembly of point sources within a spatial distribution. In this paper, we explore the estimation of the two-dimensional incoherently distributed sources using double L-shape arrays. The rotational invariance properties of the nominal elevation and nominal elevation are firstly obtained by taking first-order Taylor series expansions with regard to the generalized steering vectors of two pairs of parallel subarrays. The rotation operators can be solved based on signal subspace. Then the nominal elevation and nominal elevation can be obtained from parameters matching method. Estimation of direction of arrival can be used in multi-source scenario and needn't peak-finding search. Lastly the angular spreads can be solved through two-dimensional Capon search based on nominal angles. The simulation experiments show that the proposed method has good performance on the estimation of two-dimensional incoherently distributed sources. Investigating different experimental conditions, sources with different angular spreads, simulations are conducted to validate better estimation accuracy of the proposed method.

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36

Maia, I. A., P. Jordan, A. V. G. Cavalieri, and V. Jaunet. "Two-point wavepacket modelling of jet noise." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, no. 2227 (July 2019): 20190199. http://dx.doi.org/10.1098/rspa.2019.0199.

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This paper is focused on the study of a kinematic wavepacket model for jet noise based on two-point statistics. The model contains physical parameters that define its structure in terms of wavenumber, envelope shape and coherence decay. These parameters, which are necessary to estimate the sound pressure levels radiated by the source, were educed from a large-eddy simulation database of a Mach 0.4, fully turbulent jet. The sound pressure levels predicted by the model were compared with acoustic data and the results show that when the parameters are carefully educed from the data, the sound pressure levels generated are in good agreement with experimentally measured values for low Strouhal numbers and polar angles. Furthermore, here we show that a correct representation of both coherence decay and wavepacket envelope shape are key aspects to an accurate sound prediction. A Spectral Proper Orthogonal Decomposition (SPOD) of the model source was also performed motivated by the search for a low-rank model capable of capturing the acoustic efficiency of the full source. It is shown that only a few SPOD modes are necessary to recover acoustically important wavepacket traits.

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37

Lin, Z., D. E. Radcliffe, M. B. Beck, and L. M. Risse. "Modeling phosphorus in the upper Etowah River basin: identifying sources under uncertainty." Water Science and Technology 56, no. 6 (September 1, 2007): 29–37. http://dx.doi.org/10.2166/wst.2007.584.

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The Uniform Covering by Probabilistic Rejection (UCPR) algorithm was used, in conjunction with the Soil and Water Assessment Tool (SWAT) model, to identify P loads from point source and nonpoint source polluters in the upper Etowah River basin (UERB) in Georgia. The key findings of the research are as follows. The mean absolute error was preferred over the root mean square error as a search criterion for the UCPR algorithm when water quality observations are scarce. The undocumented P load from point sources in the UERB was consistently estimated as about 43 kg/d by the proposed method; but the method was not able to identify the broiler litter application rate to the poultry/beef operation pastures. Point sources (both documented and undocumented), poultry/beef operation pastures, and forests are the three major contributors of P. During 1992-1996, on average they accounted for 36.4, 31.7, and 17.2% of P load from the UERB, respectively.

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38

Xiao, Yue. "A New Method for Determining Optimal Regularization Parameter in Near-Field Acoustic Holography." Shock and Vibration 2018 (2018): 1–13. http://dx.doi.org/10.1155/2018/7303294.

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Tikhonov regularization method is effective in stabilizing reconstruction process of the near-field acoustic holography (NAH) based on the equivalent source method (ESM), and the selection of the optimal regularization parameter is a key problem that determines the regularization effect. In this work, a new method for determining the optimal regularization parameter is proposed. The transfer matrix relating the source strengths of the equivalent sources to the measured pressures on the hologram surface is augmented by adding a fictitious point source with zero strength. The minimization of the norm of this fictitious point source strength is as the criterion for choosing the optimal regularization parameter since the reconstructed value should tend to zero. The original inverse problem in calculating the source strengths is converted into a univariate optimization problem which is solved by a one-dimensional search technique. Two numerical simulations with a point driven simply supported plate and a pulsating sphere are investigated to validate the performance of the proposed method by comparison with the L-curve method. The results demonstrate that the proposed method can determine the regularization parameter correctly and effectively for the reconstruction in NAH.

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39

Waite, Thomas A., and John D. Reeve. "Caching Behaviour in the Gray Jay and the Source-Departure Decision for Rate-Maximizing Scatterhoarders." Behaviour 120, no. 1-2 (1992): 51–67. http://dx.doi.org/10.1163/156853992x00200.

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AbstractWe developed a model that concerns, in part, how long a scatterhoarder should persist in caching food from an ephemeral, locally abundant source ('bonanza') before moving on in search of other sources. The model assumes that an animal scattering food caches for later use behaves in a manner that maximizes the rate at which it stores recoverable (surviving) food in its habitat. It is shown theoretically that under some conditions it is better not to cache all available food but instead to move on in search of other food sources. This 'source-departure decision' for scatterhoarders is analogous to the patch-departure decision for animals that forage among food patches. It is shown that whether, and at what point, a 'moving-on threshold' is reached should depend on the size of the source, the strength of density-dependent cache theft, and the abundance of sources in the habitat. A field experiment was performed to test the qualitative prediction that gray jays, Perisoreus canadensis, should not persist as long in caching food when a day-long opportunity for caching is restricted to a single source (single-source treatment) as when such an opportunity is divided among a series of disjunct sources (multiple-source treatment). In the single-source treatment, jays tended to cache at lower overall rates, transport food items to more distant cache sites, and spend less time caching. These tendencies became more pronounced later in the day. However, although the rate of caching approached zero in the single-source treatment, the jays did not completely cease caching. This apparent violation of the model is attributed to the behaviour of recaching, a facet of gray jay scatterhoarding behaviour that was not built into the model. This retrieval and redistribution of previous caches resulted in the stabilization of the density of caches near the source. In addition, this switch from single- to multiple-load caching trips arguably would make it economical for gray jays to continue to make caching trips from a source beyond the source-departure point predicted by the model. Our theoretical and empirical results begin to show how scatterhoarders may behave in a manner that maximizes the long-term average rate of storage of recoverable food energy throughout their habitat.

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40

Collentine, D. "Search for the northwest passage: the assignation of NSP (non-point source pollution) rights in nutrient trading programs." Water Science and Technology 45, no. 9 (May 1, 2002): 227–34. http://dx.doi.org/10.2166/wst.2002.0245.

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The search for solutions to the problem of non-point source pollution (NSP) includes alternatives based on theories associated with the use of tradable pollution permits. Tradable permit programs have received significant support as a promising policy for the reduction of effluent discharges but programs in practice have not been regarded as successful. The lack of success is ascribed to the design of the programs. However, this may be a design problem which is insurmountable due to the nature of the NSP problem. Tradable permit solutions are based on an assumption that the assignation of quantifiable rights to both point and nonpoint sources, based on some predetermined ambient water quality measure, is possible. The conclusion here is that there are significant features particular to NSP that hinder the introduction of rights and significantly decrease the utility of tradable permit solutions.

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41

Reznik, A. L., A. A. Solov’ev, and A. V. Torgov. "Algorithms for Optimal Localization of a Random Point-Pulse Source Uniformly Distributed over a Search Interval." Pattern Recognition and Image Analysis 28, no. 2 (April 2018): 354–61. http://dx.doi.org/10.1134/s1054661818020177.

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42

Boccaletti, A., E. Pantin, F. Ménard, R. Galicher, M. Langlois, M. Benisty, R. Gratton, et al. "Investigating point sources in MWC 758 with SPHERE." Astronomy & Astrophysics 652 (August 2021): L8. http://dx.doi.org/10.1051/0004-6361/202141177.

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Context. Spiral arms in protoplanetary disks could be shown to be the manifestation of density waves launched by protoplanets and propagating in the gaseous component of the disk. At least two point sources have been identified in the L band in the MWC 758 system as planetary mass object candidates. Aims. We used VLT/SPHERE to search for counterparts of these candidates in the H and K bands, and to characterize the morphology of the spiral arms. Methods. The data were processed with now-standard techniques in high-contrast imaging to determine the limits of detection, and to compare them to the luminosity derived from L band observations. Results. In considering the evolutionary, atmospheric, and opacity models we were not able to confirm the two former detections of point sources performed in the L band. In addition, the analysis of the spiral arms from a dynamical point of view does not support the hypothesis that these candidates comprise the origin of the spirals. Conclusions. Deeper observations and longer timescales will be required to identify the actual source of the spiral arms in MWC 758.

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43

Sicilian, Dominic, Dannell Lopez, Massimo Moscetti, Esra Bulbul, and Nico Cappelluti. "Constraining Sterile Neutrino Dark Matter in the Milky Way Halo with Swift-XRT." Astrophysical Journal 941, no. 1 (December 1, 2022): 2. http://dx.doi.org/10.3847/1538-4357/ac9fcf.

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Abstract We present a search for sterile neutrino dark matter decay signals in the Milky Way’s dark matter halo by considering the entirety of the Swift X-ray Telescope (Swift-XRT) data archive. After filtering the raw archive, we analyze a ∼77 Ms data set containing the full field of view, as well as a ∼41 Ms data set with point sources excised using the Swift-XRT Point Source catalog. We report nondetections of emission lines across the 3–6 keV continuum in both data sets, including at and around 3.5 keV. The point-source-excised data set is found to have higher sensitivity to faint dark matter decay signals due to its freedom from point-source contamination and is thus used to set constraints. Nondetections across the total data set’s continuum are used to constrain the sterile neutrino dark matter parameter space, marginally strengthening existing X-ray constraints. Nondetections at ∼3.5 keV in data subsets grouped by angular distance from the galactic center are used to constrain the 3.5 keV line’s galactic intensity profile, providing the strongest constraints to date across ∼1/4 of the galaxy.

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44

Emerson, J. P. "IRAS and Star Formation in Dark Clouds." Symposium - International Astronomical Union 115 (1987): 19–31. http://dx.doi.org/10.1017/s0074180900094778.

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As a first step in systematically studying star formation in dark clouds we report a search for IRAS Point Source Catalog detections lieing within the boundaries of Southern Dark Clouds in the catalog of Hartley et al. (1986). To aid in further classifying the 1099 objects by their infrared colours the colours of the whole IRAS Point Source Catalog are discussed and plotted, and the regions occupied by various types of objects tabulated. The presence of Cirrus makes it difficult to confidently identify protostellar like objects from IRAS data alone. Nevertheless 247 sources have colours characteristic of objects deeply embedded in the dark clouds and are probably at least young stars of low mass. These sources appear to be located at random positions within the dark cloud volumes and there is no evidence to suggest that formation of low mass stars in this dark cloud sample is externally triggered.

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45

Wu, Chun, Wen Xin Ma, Ya Ping Chen, Ying Li, Yan Chen, and Li Jing. "A New Method of Total Amount Control of Atmospheric Pollution Based on the Genetic Algorithm." Advanced Materials Research 955-959 (June 2014): 1263–66. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1263.

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In this paper, a genetic algorithm is used has been a new method of total amount control of atmospheric pollution. The global search optimization genetic algorithm with adaptive characteristics, from the point of control the concentration distribution of source density, the source intensity distribution satisfies the requirement of the root of the total amount control. The implementation of the method is: will emissions of various pollution sources in the area of coding of chromosome, genome group according to the biological evolution regularity in the evolution of the simulation environment of natural selection, after the evolution of several generations, finally to get the best the best individual represents the intensity distribution of the source. The research results show that this method is effective and feasible.

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46

Aartsen, M. G., M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, M. Ahrens, C. Alispach, et al. "A Search for Neutrino Point-source Populations in 7 yr of IceCube Data with Neutrino-count Statistics." Astrophysical Journal 893, no. 2 (April 20, 2020): 102. http://dx.doi.org/10.3847/1538-4357/ab7af9.

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47

Church, S. E., P. D. Mauskopf, P. A. R. Ade, M. J. Devlin, W. L. Holzapfel, T. M. Wilbanks, and A. E. Lange. "An arcminute-resolution search at 4.7 inverse centimeters for point source confusion to mesurements of CMB anisotropy." Astrophysical Journal 440 (February 1995): L33. http://dx.doi.org/10.1086/187754.

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48

Masuyama, Hiroyuki, and Koichi Mizutani. "Reflection Point Search Using Rectangular Sound Source Improved by Introduction of Array with Small Number of Elements." Japanese Journal of Applied Physics 48, no. 7 (July 21, 2009): 07GC05. http://dx.doi.org/10.1143/jjap.48.07gc05.

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49

Markiewicz, Jakub Stefan. "THE USE OF COMPUTER VISION ALGORITHMS FOR AUTOMATIC ORIENTATION OF TERRESTRIAL LASER SCANNING DATA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 315–22. http://dx.doi.org/10.5194/isprs-archives-xli-b3-315-2016.

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The paper presents analysis of the orientation of terrestrial laser scanning (TLS) data. In the proposed data processing methodology, point clouds are considered as panoramic images enriched by the depth map. Computer vision (CV) algorithms are used for orientation, which are applied for testing the correctness of the detection of tie points and time of computations, and for assessing difficulties in their implementation. The BRISK, FASRT, MSER, SIFT, SURF, ASIFT and CenSurE algorithms are used to search for key-points. The source data are point clouds acquired using a Z+F 5006h terrestrial laser scanner on the ruins of Iłża Castle, Poland. Algorithms allowing combination of the photogrammetric and CV approaches are also presented.

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50

Markiewicz, Jakub Stefan. "THE USE OF COMPUTER VISION ALGORITHMS FOR AUTOMATIC ORIENTATION OF TERRESTRIAL LASER SCANNING DATA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 315–22. http://dx.doi.org/10.5194/isprsarchives-xli-b3-315-2016.

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The paper presents analysis of the orientation of terrestrial laser scanning (TLS) data. In the proposed data processing methodology, point clouds are considered as panoramic images enriched by the depth map. Computer vision (CV) algorithms are used for orientation, which are applied for testing the correctness of the detection of tie points and time of computations, and for assessing difficulties in their implementation. The BRISK, FASRT, MSER, SIFT, SURF, ASIFT and CenSurE algorithms are used to search for key-points. The source data are point clouds acquired using a Z+F 5006h terrestrial laser scanner on the ruins of Iłża Castle, Poland. Algorithms allowing combination of the photogrammetric and CV approaches are also presented.

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