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Search Results: 1 - 10 of 260353 matches for " I. G. Wisher "
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Blazar Alerts with the HAWC Online Flare Monitor
Thomas Weisgarber,Ian G. Wisher,for the HAWC Collaboration
Physics , 2015,
Abstract: The High Altitude Water Cherenkov (HAWC) Observatory monitors the gamma-ray sky in the 100 GeV to 100 TeV energy range with > 95% uptime and unprecedented sensitivity for a survey instrument. The HAWC Collaboration has implemented an online flare monitor that detects episodes of rapid flaring activity from extragalactic very high energy (VHE) sources in the declination band from -26 to 64 degrees. This allows timely alerts to be sent to multiwavelength instruments without human intervention. The preliminary configuration of the online flare monitor achieves sensitivity to flares of at least 1 hour duration that attain an average flux of 10 times that of the Crab Nebula. While flares of this magnitude are not common, several flares reaching the level of 10 Crab have been observed in the VHE band within the past decade. With its survey capabilities and high duty cycle, HAWC will expand the observational data set on these particularly extreme flares. We characterize the sensitivity of the online flare monitor and outline plans for its upcoming deployment.
The Effectiveness of Web-Based Instruction: An Initial Inquiry
Tatana M. Olson,Robert A. Wisher
International Review of Research in Open and Distance Learning , 2002,
Abstract: As the use of Web-based instruction increases in the educational and training domains, many people have recognized the importance of evaluating its effects on student outcomes such as learning, performance, and satisfaction. Often, these results are compared to those of conventional classroom instruction in order to determine which method is “better.” However, major differences in technology and presentation rather than instructional content can obscure the true relationship between Web-based instruction and these outcomes. Computer-based instruction (CBI), with more features similar to Web-based instruction, may be a more appropriate benchmark than conventional classroom instruction. Furthermore, there is little consensus as to what variables should be examined or what measures of learning are the most appropriate, making comparisons between studies difficult and inconclusive. In this article, we review the historical findings of CBI as an appropriate benchmark to Web-based instruction. In addition, we review 47 reports of evaluations of Web-based courses in higher education published between 1996 and 2002. A tabulation of the documented findings into eight characteristics is offered, along with our assessments of the experimental designs, effect sizes, and the degree to which the evaluations incorporated features unique to Web-based instruction.
The Influence of Ultrasonic Treatment on the Properties of Schottky Diodes  [PDF]
I. G. Pashayev
Open Journal of Acoustics (OJA) , 2013, DOI: 10.4236/oja.2013.33A002
Abstract: The given work studies the reason of the change of a superfluous current near crystallization temperature of an amorphous αPbSb metal alloy and at the same time founds out the influence of ultrasonic processing (USP) on the properties of αPbSb-nSi solar elements (SE), made by Shottki diodes technology (ShD) with a metal alloy. It is found that occurrence of a superfluous current αPbSb-nSi ShD under the influence of thermoannealing is connected with changes of structure of an amorphous film of metal at transition in a polycrystalline condition. VAC damaged αPbSb-nSi Sh Dare very sensitive to annealing time. Eventually, even at room temperature, level of a superfluous current decreases, i.e. the wound put by mechanical damage sort of heals, restoration process occurs the faster, the higher the annealing temperature is. Function of γt annealing parameters changes in an interval\"\" and the influence USP on photo-electric properties αPbSb-nSi SE depends on the chosen UIT mode.
Design and Efficient Controller for Micro Turbine System  [PDF]
G. Saravanan, I. Gnanambal
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78106
Abstract: In this modern era, power generation seems to be a very demanding factor. New models and methods have been proposed to derive from various natural and manmade resources. In such instances, this paper gives a detailed report on the power generation from Micro Turbines. Microturbine plays a very important role in electric power generation. Especially they are used in thecombined cycle process power plants. The parameters of Rowen’s model 265-MW single shaftheavy duty gas turbines which are used in dynamic studies are estimated in this paper using the operational and performance data. These data are also used to briefly explain the extraction of parameters of the used model. Micro turbine parameters are approximated using simple thermodynamics assumptions. Micro turbine power generation seems to be an uprising and a promisingsource and an exact design with a perfect model is capable of producing the highest efficiency.Thus this paper is proposed on the aspects of social awareness to elaborate the control design ofMicro Turbine Power Generation System. The parameters of micro turbine models are derivedand the results of several simulated tests using Matlab/Simulink are presented.
HAWC Contributions to the 34th International Cosmic Ray Conference (ICRC2015)
HAWC Collaboration,A. U. Abeysekara,R. Alfaro,C. Alvarez,J. D. álvarez,R. Arceo,J. C. Arteaga-Velázquez,H. A. Ayala Solares,A. S. Barber,B. M. Baughman,N. Bautista-Elivar,J. Becerra Gonzalez,A. Becerril,E. Belmont,S. Y. BenZvi,D. Berley,A. Bernal,J. Braun,K. S. Caballero-Mora,T. Capistrán,A. Carrami?ana,M. Castillo,U. Cotti,J. Cotzomi,S. Couti?o de León,E. de la Fuente,C. De León,T. DeYoung,R. Diaz Hernandez,L. Diaz-Cruz,J. C. Díaz-Vélez,B. L. Dingus,M. A. DuVernois,R. W. Ellsworth,K. Engel,O. Enriquez-Rivera,B. Fick,D. W. Fiorino,J. L. Flores,N. Fraija,G. Garcia-Torales,F. Garfias,M. M. González,J. A. Goodman,M. Gussert,Z. Hampel-Arias,P. Hansen,J. Patrick Harding,S. Hernandez,C. M. Hui,P. Hüntemeyer,A. Imran,A. Iriarte,P. Karn,D. Kieda,G. J. Kunde,A. Lara,R. J. Lauer,W. H. Lee,D. Lennarz,H. León Vargas,J. T. Linnemann,M. Longo Proper,G. Luis Raya,R. Luna-García,K. Malone,A. Marinelli,S. S. Marinelli,H. Martinez,O. Martinez,J. Martínez-Castro,J. A. J. Matthews,J. McEnery,P. Miranda-Romagnoli,E. Moreno,M. Mostafá,L. Nellen,M. Newbold,M. Un Nisa,R. Noriega-Papaqui,T. Oceguera-Becerra,B. Patricelli,R. Pelayo,E. G. Pérez-Pérez,J. Pretz,Z. Ren,C. D. Rho,C. Rivière,D. Rosa-González,J. Ryan,H. Salazar,F. Salesa Greus,A. Sandoval,M. Schneider,G. Sinnis,A. J. Smith,A. W. Smith,K. Sparks Woodle,R. W. Springer,I. Taboada,O. Tibolla,P. A. Toale,K. Tollefson,I. Torres,T. N. Ukwatta,L. Villase?or,T. Weisgarber,S. Westerhoff,I. G. Wisher,J. Wood,T. Yapici,G. B. Yodh,P. W. Younk,A. Zepeda
Physics , 2015,
Abstract: List of proceedings from the HAWC Collaboration presented at the 34th International Cosmic Ray Conference, 30 July - 6 August 2015, The Hague, The Netherlands.
Sensitivity of the High Altitude Water Cherenkov Detector to Sources of Multi-TeV Gamma Rays
A. U. Abeysekara,R. Alfaro,C. Alvarez,J. D. álvarez,R. Arceo,J. C. Arteaga-Velázquez,H. A. Ayala Solares,A. S. Barber,B. M. Baughman,N. Bautista-Elivar,E. Belmont,S. Y. BenZvi,D. Berley,M. Bonilla Rosales,J. Braun,R. A. Caballero-Lopez,A. Carrami?ana,M. Castillo,U. Cotti,J. Cotzomi,E. de la Fuente,C. De León,T. DeYoung,R. Diaz Hernandez,J. C. Diaz-Velez,B. L. Dingus,M. A. DuVernois,R. W. Ellsworth,A. Fernandez,D. W. Fiorino,N. Fraija,A. Galindo,J. L. Garcia-Luna,G. Garcia-Torales,F. Garfias,L. X. González,M. M. González,J. A. Goodman,V. Grabski,M. Gussert,Z. Hampel-Arias,C. M. Hui,P. Hüntemeyer,A. Imran,A. Iriarte,P. Karn,D. Kieda,G. J. Kunde,A. Lara,R. J. Lauer,W. H. Lee,D. Lennarz,H. León Vargas,E. C. Linares,J. T. Linnemann,M. Longo,R. Luna-Garc\'\ia,A. Marinelli,O. Martinez,J. Mart\'\inez-Castro,J. A. J. Matthews,P. Miranda-Romagnoli,E. Moreno,M. Mostafá,J. Nava,L. Nellen,M. Newbold,R. Noriega-Papaqui,T. Oceguera-Becerra,B. Patricelli,R. Pelayo,E. G. Pérez-Pérez,J. Pretz,C. Rivière,D. Rosa-González,H. Salazar,F. Salesa,A. Sandoval,E. Santos,M. Schneider,S. Silich,G. Sinnis,A. J. Smith,K. Sparks,R. W. Springer,I. Taboada,P. A. Toale,K. Tollefson,I. Torres,T. N. Ukwatta,L. Villase?or,T. Weisgarber,S. Westerhoff,I. G. Wisher,J. Wood,G. B. Yodh,P. W. Younk,D. Zaborov,A. Zepeda,H. Zhou
Physics , 2013, DOI: 10.1016/j.astropartphys.2013.08.002
Abstract: The High Altitude Water Cherenkov (HAWC) observatory is an array of large water Cherenkov detectors sensitive to gamma rays and hadronic cosmic rays in the energy band between 100 GeV and 100 TeV. The observatory will be used to measure high-energy protons and cosmic rays via detection of the energetic secondary particles reaching the ground when one of these particles interacts in the atmosphere above the detector. HAWC is under construction at a site 4100 meters above sea level on the northern slope of the volcano Sierra Negra, which is located in central Mexico at 19 degrees N latitude. It is scheduled for completion in 2014. In this paper we estimate the sensitivity of the HAWC instrument to point-like and extended sources of gamma rays. The source fluxes are modeled using both unbroken power laws and power laws with exponential cutoffs. HAWC, in one year, is sensitive to point sources with integral power-law spectra as low as 5x10^-13 cm^-2 sec^-1 above 2 TeV (approximately 50 mCrab) over 5 sr of the sky. This is a conservative estimate based on simple event parameters and is expected to improve as the data analysis techniques are refined. We discuss known TeV sources and the scientific contributions that HAWC can make to our understanding of particle acceleration in these sources.
Search for gamma-rays from the unusually bright GRB 130427A with the HAWC Gamma-ray Observatory
A. U. Abeysekara,R. Alfaro,C. Alvarez,J. D. álvarez,R. Arceo,J. C. Arteaga-Velázquez,H. A. Ayala Solares,A. S. Barber,B. M. Baughman,N. Bautista-Elivar,S. Y. BenZvi,M. Bonilla Rosales,J. Braun,K. S. Caballero-Mora,A. Carrami?ana,M. Castillo,U. Cotti,J. Cotzomi,E. de la Fuente,C. De León,T. DeYoung,R. Diaz Hernandez,B. L. Dingus,M. A. DuVernois,R. W. Ellsworth,D. W. Fiorino,N. Fraija,A. Galindo,F. Garfias,M. M. González,J. A. Goodman,M. Gussert,Z. Hampel-Arias,J. P. Harding,P. Hüntemeyer,C. M. Hui,A. Imran,A. Iriarte,P. Karn,D. Kieda,G. J. Kunde,A. Lara,R. J. Lauer,W. H. Lee,D. Lennarz,H. León Vargas,J. T. Linnemann,M. Longo,R. Luna-García,K. Malone,A. Marinelli,S. S. Marinelli,H. Martinez,O. Martinez,J. Martínez-Castro,J. A. J. Matthews,E. Mendoza Torres,P. Miranda-Romagnoli,E. Moreno,M. Mostafá,L. Nellen,M. Newbold,R. Noriega-Papaqui,T. O. Oceguera-Becerra,B. Patricelli,R. Pelayo,E. G. Pérez-Pérez,J. Pretz,C. Rivière,D. Rosa-González,H. Salazar,F. Salesa Greus,A. Sandoval,M. Schneider,G. Sinnis,A. J. Smith,K. Sparks Woodle,R. W. Springer,I. Taboada,K. Tollefson,I. Torres,T. N. Ukwatta,L. Villase?or,T. Weisgarber,S. Westerhoff,I. G. Wisher,J. Wood,G. B. Yodh,P. W. Younk,D. Zaborov,A. Zepeda,H. Zhou
Physics , 2014, DOI: 10.1088/0004-637X/800/2/78
Abstract: The first limits on the prompt emission from the long gamma-ray burst (GRB) 130427A in the $>100\nobreakspace\rm{GeV}$ energy band are reported. GRB 130427A was the most powerful burst ever detected with a redshift $z\lesssim0.5$ and featured the longest lasting emission above $100\nobreakspace\rm{MeV}$. The energy spectrum extends at least up to $95\nobreakspace\rm{GeV}$, clearly in the range observable by the High Altitude Water Cherenkov (HAWC) Gamma-ray Observatory, a new extensive air shower detector currently under construction in central Mexico. The burst occurred under unfavourable observation conditions, low in the sky and when HAWC was running 10% of the final detector. Based on the observed light curve at MeV-GeV energies, eight different time periods have been searched for prompt and delayed emission from this GRB. In all cases, no statistically significant excess of counts has been found and upper limits have been placed. It is shown that a similar GRB close to zenith would be easily detected by the full HAWC detector, which will be completed soon. The detection rate of the full HAWC detector may be as high as one to two GRBs per year. A detection could provide important information regarding the high energy processes at work and the observation of a possible cut-off beyond the $\mathit{Fermi}$-LAT energy range could be the signature of gamma-ray absorption, either in the GRB or along the line of sight due to the extragalactic background light.
The HAWC Gamma-Ray Observatory: Design, Calibration, and Operation
HAWC Collaboration,A. U. Abeysekara,R. Alfaro,C. Alvarez,J. D. álvarez,R. Arceo,J. C. Arteaga-Velázquez,H. A. Ayala Solares,A. S. Barber,B. M. Baughman,N. Bautista-Elivar,E. Belmont,S. Y. BenZvi,D. Berley,M. Bonilla Rosales,J. Braun,R. A. Caballero-Lopez,K. S. Caballero-Mora,A. Carrami?ana,M. Castillo,U. Cotti,J. Cotzomi,E. de la Fuente,C. De León,T. DeYoung,R. Diaz Hernandez,J. C. Díaz-Vélez,B. L. Dingus,M. A. DuVernois,R. W. Ellsworth,A. Fernandez,D. W. Fiorino,N. Fraija,A. Galindo,F. Garfias,L. X. González,M. M. González,J. A. Goodman,V. Grabski,M. Gussert,Z. Hampel-Arias,C. M. Hui,P. Hüntemeyer,A. Imran,A. Iriarte,P. Karn,D. Kieda,G. J. Kunde,A. Lara,R. J. Lauer,W. H. Lee,D. Lennarz,H. León Vargas,E. C. Linares,J. T. Linnemann,M. Longo,R. Luna-GarcIa,A. Marinelli,H. Martinez,O. Martinez,J. Martínez-Castro,J. A. J. Matthews,P. Miranda-Romagnoli,E. Moreno,M. Mostafá,J. Nava,L. Nellen,M. Newbold,R. Noriega-Papaqui,T. Oceguera-Becerra,B. Patricelli,R. Pelayo,E. G. Pérez-Pérez,J. Pretz,C. Rivière,D. Rosa-González,H. Salazar,F. Salesa,F. E. Sanchez,A. Sandoval,E. Santos,M. Schneider,S. Silich,G. Sinnis,A. J. Smith,K. Sparks,R. W. Springer,I. Taboada,P. A. Toale,K. Tollefson,I. Torres,T. N. Ukwatta,L. Villase?or,T. Weisgarber,S. Westerhoff,I. G. Wisher,J. Wood,G. B. Yodh,P. W. Younk,D. Zaborov,A. Zepeda,H. Zhou
Physics , 2013,
Abstract: The High-Altitude Water Cherenkov Gamma Ray Observatory (HAWC) is under construction 4100 meters above sea level at Sierra Negra, Mexico. We describe the design and cabling of the detector, the characterization of the photomultipliers, and the timing calibration system. We also outline a next-generation detector based on the water Cherenkov technique.
The HAWC Gamma-Ray Observatory: Observations of Cosmic Rays
HAWC Collaboration,A. U. Abeysekara,R. Alfaro,C. Alvarez,J. D. álvarez,R. Arceo,J. C. Arteaga-Velázquez,H. A. Ayala Solares,A. S. Barber,B. M. Baughman,N. Bautista-Elivar,E. Belmont,S. Y. BenZvi,D. Berley,M. Bonilla Rosales,J. Braun,R. A. Caballero-Lopez,K. S. Caballero-Mora,A. Carrami?ana,M. Castillo,U. Cotti,J. Cotzomi,E. de la Fuente,C. De León,T. DeYoung,R. Diaz Hernandez,J. C. Díaz-Vélez,B. L. Dingus,M. A. DuVernois,R. W. Ellsworth,A. Fernandez,D. W. Fiorino,N. Fraija,A. Galindo,F. Garfias,L. X. González,M. M. González,J. A. Goodman,V. Grabski,M. Gussert,Z. Hampel-Arias,C. M. Hui,P. Hüntemeyer,A. Imran,A. Iriarte,P. Karn,D. Kieda,G. J. Kunde,A. Lara,R. J. Lauer,W. H. Lee,D. Lennarz,H. León Vargas,E. C. Linares,J. T. Linnemann,M. Longo,R. Luna-GarcIa,A. Marinelli,H. Martinez,O. Martinez,J. Martínez-Castro,J. A. J. Matthews,P. Miranda-Romagnoli,E. Moreno,M. Mostafá,J. Nava,L. Nellen,M. Newbold,R. Noriega-Papaqui,T. Oceguera-Becerra,B. Patricelli,R. Pelayo,E. G. Pérez-Pérez,J. Pretz,C. Rivière,D. Rosa-González,H. Salazar,F. Salesa,F. E. Sanchez,A. Sandoval,E. Santos,M. Schneider,S. Silich,G. Sinnis,A. J. Smith,K. Sparks,R. W. Springer,I. Taboada,P. A. Toale,K. Tollefson,I. Torres,T. N. Ukwatta,L. Villase?or,T. Weisgarber,S. Westerhoff,I. G. Wisher,J. Wood,G. B. Yodh,P. W. Younk,D. Zaborov,A. Zepeda,H. Zhou
Physics , 2013,
Abstract: We describe measurements of GeV and TeV cosmic rays with the High-Altitude Water Cherenkov Gamma-Ray Observatory, or HAWC. The measurements include the observation of the shadow of the moon; the observation of small-scale and large-scale angular clustering of the TeV cosmic rays; the prospects for measurement of transient solar events with HAWC; and the observation of Forbush decreases with the HAWC engineering array and HAWC-30.
The HAWC Gamma-Ray Observatory: Dark Matter, Cosmology, and Fundamental Physics
HAWC Collaboration,A. U. Abeysekara,R. Alfaro,C. Alvarez,J. D. álvarez,R. Arceo,J. C. Arteaga-Velázquez,H. A. Ayala Solares,A. S. Barber,B. M. Baughman,N. Bautista-Elivar,E. Belmont,S. Y. BenZvi,D. Berley,M. Bonilla Rosales,J. Braun,R. A. Caballero-Lopez,K. S. Caballero-Mora,A. Carrami?ana,M. Castillo,U. Cotti,J. Cotzomi,E. de la Fuente,C. De León,T. DeYoung,R. Diaz Hernandez,J. C. Díaz-Vélez,B. L. Dingus,M. A. DuVernois,R. W. Ellsworth,A. Fernandez,D. W. Fiorino,N. Fraija,A. Galindo,F. Garfias,L. X. González,M. M. González,J. A. Goodman,V. Grabski,M. Gussert,Z. Hampel-Arias,C. M. Hui,P. Hüntemeyer,A. Imran,A. Iriarte,P. Karn,D. Kieda,G. J. Kunde,A. Lara,R. J. Lauer,W. H. Lee,D. Lennarz,H. León Vargas,E. C. Linares,J. T. Linnemann,M. Longo,R. Luna-GarcIa,A. Marinelli,H. Martinez,O. Martinez,J. Martínez-Castro,J. A. J. Matthews,P. Miranda-Romagnoli,E. Moreno,M. Mostafá,J. Nava,L. Nellen,M. Newbold,R. Noriega-Papaqui,T. Oceguera-Becerra,B. Patricelli,R. Pelayo,E. G. Pérez-Pérez,J. Pretz,C. Rivière,D. Rosa-González,H. Salazar,F. Salesa,F. E. Sanchez,A. Sandoval,E. Santos,M. Schneider,S. Silich,G. Sinnis,A. J. Smith,K. Sparks,R. W. Springer,I. Taboada,P. A. Toale,K. Tollefson,I. Torres,T. N. Ukwatta,L. Villase?or,T. Weisgarber,S. Westerhoff,I. G. Wisher,J. Wood,G. B. Yodh,P. W. Younk,D. Zaborov,A. Zepeda,H. Zhou
Physics , 2013,
Abstract: The High-Altitude Water Cherenkov Gamma Ray Observatory (HAWC) is designed to perform a synoptic survey of the TeV sky. The high energy coverage of the experiment will enable studies of fundamental physics beyond the Standard Model, and the large field of view of the detector will enable detailed studies of cosmologically significant backgrounds and magnetic fields. We describe the sensitivity of the full HAWC array to these phenomena in five contributions shown at the 33rd International Cosmic Ray Conference in Rio de Janeiro, Brazil (July 2013).
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