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2. Mitigating calibration errors from mutual coupling with time-domain filtering of 21 cm cosmological radio observations

Author

Charles, N., Kern, N. S., Pascua, R., Bernardi, G., Bester, L., Smirnov, O., Acedo, E. d. L., Abdurashidova, Z., Adams, T., Aguirre, J. E., Baartman, R., Beardsley, A. P., Berkhout, L. M., Billings, T. S., Bowman, J. D., Bull, P., Burba, J., Byrne, R., Carey, S., Chen, K., Choudhuri, S., Cox, T., DeBoer, D. R., Dexter, M., Dillon, J. S., Dynes, S., Eksteen, N., Ely, J., Ewall-Wice, A., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Garsden, H., Gehlot, B. K., Ghosh, A., Gorce, A., Gorthi, D., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Huang, T., Jacobs, D. C., Josaitis, A., Kerrigan, J., Kittiwisit, P., Kolopanis, M., Lanman, A., Liu, A., Ma, Y. -Z., MacMahon, D. H. E., Malan, L., Malgas, K., Malgas, C., Marero, B., Martinot, Z. E., McBride, L., Mesinger, A., Mohamed-Hinds, N., Molewa, M., Morales, M. F., Murray, S., Nikolic, B., Nuwegeld, H., Parsons, A. R., Patra, N., Plante, P. L., Qin, Y., Rath, E., Razavi-Ghods, N., Riley, D., Robnett, J., Rosie, K., Santos, M. G., Sims, P., Singh, S., Storer, D., Swarts, H., Tan, J., Wilensky, M. J., Williams, P. K. G., Wyngaarden, P. v., and Zheng, H.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation (EoR). This has led to the construction of low-frequency radio interferometric arrays, such as the Hydrogen Epoch of Reionization Array (HERA), aimed at systematically mapping this emission for the first time. Precision calibration, however, is a requirement in 21 cm radio observations. Due to the spatial compactness of HERA, the array is prone to the effects of mutual coupling, which inevitably lead to non-smooth calibration errors that contaminate the data. When unsmooth gains are used in calibration, intrinsically spectrally-smooth foreground emission begins to contaminate the data in a way that can prohibit a clean detection of the cosmological EoR signal. In this paper, we show that the effects of mutual coupling on calibration quality can be reduced by applying custom time-domain filters to the data prior to calibration. We find that more robust calibration solutions are derived when filtering in this way, which reduces the observed foreground power leakage. Specifically, we find a reduction of foreground power leakage by 2 orders of magnitude at k=0.5.

Published
2024

3. Investigating Mutual Coupling in the Hydrogen Epoch of Reionization Array and Mitigating its Effects on the 21-cm Power Spectrum

Author

Rath, E., Pascua, R., Josaitis, A. T., Ewall-Wice, A., Fagnoni, N., Acedo, E. de Lera, Martinot, Z. E., Abdurashidova, Z., Adams, T., Aguirre, J. E., Baartman, R., Beardsley, A. P., Berkhout, L. M., Bernardi, G., Billings, T. S., Bowman, J. D., Bull, P., Burba, J., Byrne, R., Carey, S., Chen, K. -F., Choudhuri, S., Cox, T., DeBoer, D. R., Dexter, M., Dillon, J. S., Dynes, S., Eksteen, N., Ely, J., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Garsden, H., Gehlot, B. K., Ghosh, A., Gorce, A., Gorthi, D., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Huang, T., Jacobs, D. C., Kern, N. S., Kerrigan, J., Kittiwisit, P., Kolopanis, M., Lanman, A., Liu, A., Ma, Y. -Z., MacMahon, D. H. E., Malan, L., Malgas, C., Malgas, K., Marero, B., McBride, L., Mesinger, A., Mohamed-Hinds, N., Molewa, M., Morales, M. F., Murray, S. G., Nikolic, B., Nuwegeld, H., Parsons, A. R., Patra, N., La Plante, P., Qin, Y., Razavi-Ghods, N., Riley, D., Robnett, J., Rosie, K., Santos, M. G., Sims, P., Singh, S., Storer, D., Swarts, H., Tan, J., Wilensky, M. J., Williams, P. K. G., van Wyngaarden, P., and Zheng, H.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Interferometric experiments designed to detect the highly redshifted 21-cm signal from neutral hydrogen are producing increasingly stringent constraints on the 21-cm power spectrum, but some k-modes remain systematics-dominated. Mutual coupling is a major systematic that must be overcome in order to detect the 21-cm signal, and simulations that reproduce effects seen in the data can guide strategies for mitigating mutual coupling. In this paper, we analyse 12 nights of data from the Hydrogen Epoch of Reionization Array and compare the data against simulations that include a computationally efficient and physically motivated semi-analytic treatment of mutual coupling. We find that simulated coupling features qualitatively agree with coupling features in the data; however, coupling features in the data are brighter than the simulated features, indicating the presence of additional coupling mechanisms not captured by our model. We explore the use of fringe-rate filters as mutual coupling mitigation tools and use our simulations to investigate the effects of mutual coupling on a simulated cosmological 21-cm power spectrum in a "worst case" scenario where the foregrounds are particularly bright. We find that mutual coupling contaminates a large portion of the "EoR Window", and the contamination is several orders-of-magnitude larger than our simulated cosmic signal across a wide range of cosmological Fourier modes. While our fiducial fringe-rate filtering strategy reduces mutual coupling by roughly a factor of 100 in power, a non-negligible amount of coupling cannot be excised with fringe-rate filters, so more sophisticated mitigation strategies are required., Comment: 19 pages, 12 figures, submitted to MNRAS

Published
2024

4. Understanding the HERA Phase i receiver system with simulations and its impact on the detectability of the EoR delay power spectrum

Author

Fagnoni, N, De Lera Acedo, E, Deboer, DR, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carilli, CL, Cheng, C, Dexter, M, Dillon, JS, Ewall-Wice, A, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Josaitis, A, Julius, A, Kern, NS, Kerrigan, J, Kim, H, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, Plante, PL, Lekalake, T, Liu, A, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mena Parra, J, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Neben, AR, Nikolic, B, Parsons, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Williams, PKG, and Zheng, H

Subjects
instrumentation: interferometers, methods: numerical, techniques: interferometric, telescopes, dark ages, reionization, first stars, astro-ph.IM, dark ages, reionization, Astronomy & Astrophysics, Astronomical and Space Sciences
Abstract

The detection of the Epoch of Reionization (EoR) delay power spectrum using a 'foreground avoidance method' highly depends on the instrument chromaticity. The systematic effects induced by the radio telescope spread the foreground signal in the delay domain, which contaminates the EoR window theoretically observable. Applied to the Hydrogen Epoch of Reionization Array (HERA), this paper combines detailed electromagnetic and electrical simulations in order to model the chromatic effects of the instrument, and quantify its frequency and time responses. In particular, the effects of the analogue receiver, transmission cables, and mutual coupling are included. These simulations are able to accurately predict the intensity of the reflections occurring in the 150-m cable which links the antenna to the backend. They also show that electromagnetic waves can propagate from one dish to another one through large sections of the array due to mutual coupling. The simulated system time response is attenuated by a factor 104 after a characteristic delay which depends on the size of the array and on the antenna position. Ultimately, the system response is attenuated by a factor 105 after 1400 ns because of the reflections in the cable, which corresponds to characterizable ka-modes above 0.7 $h\,\,\rm {Mpc}^{-1}$ at 150 MHz. Thus, this new study shows that the detection of the EoR signal with HERA Phase I will be more challenging than expected. On the other hand, it improves our understanding of the telescope, which is essential to mitigate the instrument chromaticity.

Published
2021

5. Detection of cosmic structures using the bispectrum phase. II. First results from application to cosmic reionization using the Hydrogen Epoch of Reionization Array

Author

Thyagarajan, N, Carilli, CL, Nikolic, B, Kent, J, Mesinger, A, Kern, NS, Bernardi, G, Matika, S, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Billings, TS, Bowman, JD, Bradley, RF, Burba, J, Carey, S, Cheng, C, Deboer, DR, Dexter, M, Acedo, EDL, Dillon, JS, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Lekalake, T, Lewis, D, Liu, A, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Molewa, M, Morales, MF, Mosiane, T, Neben, AR, Parsons, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Williams, PKG, and Zheng, H

Subjects
astro-ph.CO, astro-ph.IM
Abstract

Characterizing the epoch of reionization (EoR) at z 6 via the redshifted 21 cm line of neutral Hydrogen (H i) is critical to modern astrophysics and cosmology, and thus a key science goal of many current and planned low-frequency radio telescopes. The primary challenge to detecting this signal is the overwhelmingly bright foreground emission at these frequencies, placing stringent requirements on the knowledge of the instruments and inaccuracies in analyses. Results from these experiments have largely been limited not by thermal sensitivity but by systematics, particularly caused by the inability to calibrate the instrument to high accuracy. The interferometric bispectrum phase is immune to antenna-based calibration and errors therein, and presents an independent alternative to detect the EoR H i fluctuations while largely avoiding calibration systematics. Here, we provide a demonstration of this technique on a subset of data from the Hydrogen Epoch of Reionization Array (HERA) to place approximate constraints on the brightness temperature of the intergalactic medium (IGM). From this limited data, at z=7.7 we infer "1σ"upper limits on the IGM brightness temperature to be ≤ 316 "pseudo"mK at κ =0.33 "pseudo"h Mpc-1 (data-limited) and ≤ 1000 "pseudo"mK at κ =0.875 "pseudo"h Mpc-1 (noise-limited). The "pseudo"units denote only an approximate and not an exact correspondence to the actual distance scales and brightness temperatures. By propagating models in parallel to the data analysis, we confirm that the dynamic range required to separate the cosmic H i signal from the foregrounds is similar to that in standard approaches, and the power spectrum of the bispectrum phase is still data-limited (at 106 dynamic range) indicating scope for further improvement in sensitivity as the array build-out continues.

Published
2020

6. Redundant-baseline calibration of the hydrogen epoch of reionization array

Author

Dillon, JS, Lee, M, Ali, ZS, Parsons, AR, Orosz, N, Nunhokee, CD, La Plante, P, Beardsley, AP, Kern, NS, Abdurashidova, Z, Aguirre, JE, Alexander, P, Balfour, Y, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, de Lera Acedo, E, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, Lekalake, T, Lewis, D, Liu, A, Ma, YZ, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Murray, S, Neben, AR, Nikolic, B, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Santos, MG, Sims, P, Smith, C, Syce, A, Tegmark, M, Thyagarajan, N, Williams, PKG, and Zheng, H

Subjects
instrumentation: interferometers, dark ages, reionization, first stars, astro-ph.IM, astro-ph.CO, dark ages, reionization, first stars, Astronomy & Astrophysics, Astronomical and Space Sciences
Abstract

In 21-cm cosmology, precision calibration is key to the separation of the neutral hydrogen signal from very bright but spectrally smooth astrophysical foregrounds. The Hydrogen Epoch of Reionization Array (HERA), an interferometer specialized for 21-cm cosmology and now under construction in South Africa, was designed to be largely calibrated using the self-consistency of repeated measurements of the same interferometric modes. This technique, known as redundant-baseline calibration resolves most of the internal degrees of freedom in the calibration problem. It assumes, however, on antenna elements with identical primary beams placed precisely on a redundant grid. In this work, we review the detailed implementation of the algorithms enabling redundant-baseline calibration and report results with HERA data.We quantify the effects of real-world non-redundancy and how they compare to the idealized scenario in which redundant measurements differ only in their noise realizations. Finally, we study how non-redundancy can produce spurious temporal structure in our calibration solutions-both in data and in simulations-and present strategies for mitigating that structure.

Published
2020

7. Optimizing sparse RFI prediction using deep learning

Author

Kerrigan, J, la Plante, P, Kohn, S, Pober, JC, Aguirre, J, Abdurashidova, Z, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Bowman, JD, Bradley, RF, Burba, J, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, de Lera Acedo, E, Dillon, JS, Estrada, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Glendenning, B, Greig, B, Grobbelaar, J, Gorthi, D, Halday, Z, Hazelton, BJ, Hickish, J, Jacobs, DC, Julius, A, Kern, NS, Kittiwisit, P, Kolopanis, M, Lanman, A, Lekalake, T, Liu, A, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Neben, AR, Parsons, AR, Patra, N, Pieterse, S, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Williams, PKG, and Zheng, H

Subjects
methods: data analysis, techniques: interferometric, astro-ph.IM, astro-ph.CO, Astronomy & Astrophysics, Astronomical and Space Sciences
Abstract

Radio frequency interference (RFI) is an ever-present limiting factor among radio telescopes even in the most remote observing locations. When looking to retain the maximum amount of sensitivity and reduce contamination for Epoch of Reionization studies, the identification and removal of RFI is especially important. In addition to improved RFI identification, we must also take into account computational efficiency of the RFI-Identification algorithm as radio interferometer arrays such as the Hydrogen Epoch of Reionization Array (HERA) grow larger in number of receivers. To address this, we present a deep fully convolutional neural network (DFCN) that is comprehensive in its use of interferometric data, where both amplitude and phase information are used jointly for identifying RFI. We train the network using simulated HERA visibilities containing mock RFI, yielding a known ‘ground truth’ data set for evaluating the accuracy of various RFI algorithms. Evaluation of the DFCN model is performed on observations from the 67 dish build-out, HERA-67, and achieves a data throughput of 1.6 × 105 HERA time-ordered 1024 channelled visibilities per hour per GPU. We determine that relative to an amplitude only network including visibility phase adds important adjacent time–frequency context which increases discrimination between RFI and non-RFI. The inclusion of phase when predicting achieves a recall of 0.81, precision of 0.58, and F2 score of 0.75 as applied to our HERA-67 observations.

Published
2019

8. Design and characterization of the Large-Aperture Experiment to Detect the Dark Age (LEDA) radiometer systems

Author

Price, D. C., Greenhill, L. J., Fialkov, A., Bernardi, G., Garsden, H., Barsdell, B. R., Kocz, J., Anderson, M. M., Bourke, S. A., Craig, J., Dexter, M. R., Dowell, J., Eastwood, M. W., Eftekhari, T., Ellingson, S. W., Hallinan, G., Hartman, J. M., Kimberk, R., Lazio, T. J. W., Leiker, S., MacMahon, D., Monroe, R., Schinzel, F., Taylor, G. B., Tong, E., Werthimer, D., and Woody, D. P.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Large-Aperture Experiment to Detect the Dark Age (LEDA) was designed to detect the predicted O(100)mK sky-averaged absorption of the Cosmic Microwave Background by Hydrogen in the neutral pre- and intergalactic medium just after the cosmological Dark Age. The spectral signature would be associated with emergence of a diffuse Ly$\alpha$ background from starlight during 'Cosmic Dawn'. Recently, Bowman et al. (2018) have reported detection of this predicted absorption feature, with an unexpectedly large amplitude of 530 mK, centered at 78 MHz. Verification of this result by an independent experiment, such as LEDA, is pressing. In this paper, we detail design and characterization of the LEDA radiometer systems, and a first-generation pipeline that instantiates a signal path model. Sited at the Owens Valley Radio Observatory Long Wavelength Array, LEDA systems include the station correlator, five well-separated redundant dual polarization radiometers and backend electronics. The radiometers deliver a 30-85MHz band (16

Published
2017
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10. A Real Time Processing system for big data in astronomy: Applications to HERA

Author

La Plante, P., Williams, P.K.G., Kolopanis, M., Dillon, J.S., Beardsley, A.P., Kern, N.S., Wilensky, M., Ali, Z.S., Abdurashidova, Z., Aguirre, J.E., Alexander, P., Balfour, Y., Bernardi, G., Billings, T.S., Bowman, J.D., Bradley, R.F., Bull, P., Burba, J., Carey, S., Carilli, C.L., Cheng, C., DeBoer, D.R., Dexter, M., de Lera Acedo, E., Ely, J., Ewall-Wice, A., Fagnoni, N., Fritz, R., Furlanetto, S.R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B.J., Hewitt, J.N., Hickish, J., Jacobs, D.C., Julius, A., Kerrigan, J., Kittiwisit, P., Kohn, S.A., Lanman, A., Lekalake, T., Lewis, D., Liu, A., MacMahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z.E., Matsetela, E., Mesinger, A., Molewa, M., Morales, M.F., Mosiane, T., Murray, S., Neben, A.R., Nikolic, B., Parsons, A.R., Pascua, R., Patra, N., Pieterse, S., Pober, J.C., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Santos, M.G., Sims, P., Smith, C., Syce, A., Thyagarajan, N., and Zheng, H.

Published
2021
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11. Service Management System Core Transaction (Recruitment, Applicant Management, New Hire on Board, Employee Management, Recruiting Analytics & Reporting, Position / Job Management, Payroll & Payment Management, Placement Management, Client Management, Clie: Vol. 3, No. 2

Author

Dolientas, Paul Dexter M., Alibadbad, Jericho T., Frias, Jullius Y., Pamplona, Zelden B., Antojado, Dandy I., Dolientas, Paul Dexter M., Alibadbad, Jericho T., Frias, Jullius Y., Pamplona, Zelden B., and Antojado, Dandy I.

Abstract

Many companies are also offering flexible schedules to their employees, so it's not just for gig workers or freelancers anymore. During the pandemic, not only the health of many people has been affected but also their jobs. Covid -19 had a significant impact on employment in the Philippines Apparently, some employees were forced to take unpaid leave, while others stated that their jobs had been suspended and that their salary was reduced. The COVID-19 pandemic triggered one of the biggest job crises since the Great Depression. The crisis has a substantial risk of exacerbating poverty and widening inequality, with long-term effects. A social collapse brought on by the job crisis must now be avoided at all costs. The service management project will make the process easier, for it will lessen the workload and the consuming time for processing the collection of such applicant. The accuracy of the record will be maintained and manageable. To work smart rather than hard, time management is the activity of planning and exercising deliberate control over the time spent on specific activities. The researchers focused on the Agile methodology because it gained a lot of traction in recent years, and broadly acknowledged across the software development discipline and a wide range of enterprises of all sizes today. Agile is the umbrella term for a collection of software development approaches that emphasize project iteration and incremental progress. When working in a corporation with software projects, using the Agile technique is particularly beneficial because it gives for more control over the provided software.In this research, the researcher will focus on developing a Web Application for recruitment agencies. The main objective of this system is to provide web-based recruitment and monitoring system. This Web application will be used by the Human Resource Administrators and other Departments for the processing of the applicant documents, monitoring of employees, partaking

Published
2024

12. Digital Signal Processing using Stream High Performance Computing: A 512-input Broadband Correlator for Radio Astronomy

Author

Kocz, J., Greenhill, L. J, Barsdell, B. R., Price, D., Bernardi, G., Bourke, S., Clark, M. A., Craig, J., Dexter, M., Dowell, J., Eftekhari, T., Ellingson, S., Hallinan, G., Hartman, J., Jameson, A., MacMahon, D., Taylor, G., Schinzel, F., and Werthimer, D.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

A "large-N" correlator that makes use of Field Programmable Gate Arrays and Graphics Processing Units has been deployed as the digital signal processing system for the Long Wavelength Array station at Owens Valley Radio Observatory (LWA-OV), to enable the Large Aperture Experiment to Detect the Dark Ages (LEDA). The system samples a ~100MHz baseband and processes signals from 512 antennas (256 dual polarization) over a ~58MHz instantaneous sub-band, achieving 16.8Tops/s and 0.236 Tbit/s throughput in a 9kW envelope and single rack footprint. The output data rate is 260MB/s for 9 second time averaging of cross-power and 1 second averaging of total-power data. At deployment, the LWA-OV correlator was the largest in production in terms of N and is the third largest in terms of complex multiply accumulations, after the Very Large Array and Atacama Large Millimeter Array. The correlator's comparatively fast development time and low cost establish a practical foundation for the scalability of a modular, heterogeneous, computing architecture., Comment: 10 pages, 8 figures, submitted to JAI

Published
2014

15. Trends of Rainfall Pattern in the Island Province of Catanduanes, Philippines

Author

null Engr. Dexter M. Toyado, MM

Subjects
General Engineering
Abstract

The Island of Catanduanes is located in the eastern most fringe of Luzon considered to be the doorstep of typhoon path. The rainfall in the province is important in producing agricultural food to make life in the province sustainable. Hence, it is necessary to establish how the effect of climate change variable on the availability of water in the island, so that impending extreme drought or flooding will be mitigated. In addition to that, Climate change in the island has an impact on human activity, and a treat from flooding of variable weather pattern like seasonal monsoon rain and inter tropical convergence zone develop near the island. Using the data from the PAGASA-DOST, Climatology and Agro meteorology Division (CAD) of April 2020, from the Virac Doppler and Radar Weather in Catanduanes. Synoptic data were used to evaluate the rainfall for the last 30 years. The rainfall pattern caused by the southwest monsoon (Habagat) most from June to September gives an average of 73.08mm for 3 decades. Northeast monsoon (Amihan) usually arrives on November and ends on March having an average rainfall of 103.78mm for 3 decades. It has been shown that the rainfall is increasing every year, the annual rainfall trends will increase of up to 10.76mm in the next 10 years. Studying the rainfall pattern and temperature will give us more precise assessment of the climatic condition in the island and give the community and the government the proper information for mitigating and planning on how we can handle climate change.

Published
2022

16. Awareness of Disaster Risk Reduction (DRR) among Student of the Catanduanes State University

Author

null Dexter M. Toyado

Subjects
General Engineering
Abstract

The Island Province of Catanduanes is prone to all types of natural hazards that includes torrential and heavy rains, strong winds and surge, flooding and landslide or slope failures as a result of its geographical location and topography. RA 10121 mandates local DRRM bodies to “encourage community, specifically the youth, participation in disaster risk reduction and management activities, such as organizing quick response groups, particularly in identified disaster-prone areas, as well as the inclusion of disaster risk reduction and management programs as part of youth programs and projects. The study aims to determine the awareness to disaster of the student of the Catanduanes State University. The disaster-based questionnaire was prepared and distributed among 636 students selected randomly from different Colleges and Laboratory Schools in the University The Catanduanes State University students understood some disaster-related concepts and ideas, but uncertain on issues on preparedness, adaptation, and awareness on the risks inflicted by these natural hazards. Low perception on disaster risks are evidently observed among students. The responses of the students could be based on the efficiency and impact of the integration of DRR education in the senior high school curriculum. Specifically, integration of the concepts about the hazards, hazard maps, disaster preparedness, awareness, mitigation, prevention, adaptation, and resiliency in the science curriculum possibly affect the knowledge and understanding of students on DRR. Preparedness drills and other forms of capacity building must be done to improve awareness of the student towards DRRM. The study further recommends that teachers and instructor must also be capacitated in handling disaster as they are the prime movers in the implementation of the DRRM in education. Preparedness drills and other forms of capacity building must be done to improve awareness of the student towards DRRM. Core subjects in Earth Sciences must be reinforced with geologic hazards. Learning competencies must also be focused on hazard identification and mapping, and coping with different geologic disaster.

Published
2022

17. Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations

Author

Abdurashidova, THCZ, Adams, T, Aguirre, JE, Alexander, P, Ali, ZS, Baartman, R, Balfour, Y, Barkana, R, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Breitman, D, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, Choudhuri, S, DeBoer, DR, De Lera Acedo, E, Dexter, M, Dillon, JS, Ely, J, Ewall-Wice, A, Fagnoni, N, Fialkov, A, Fritz, R, Furlanetto, Gale-Sides, K, Garsden, H, Glendenning, B, Gorce, A, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Heimersheim, S, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Lewis, D, Liu, A, Loots, A, Ma, YZ, MacMahon, DHE, Malan, L, Malgas, K, Malgas, C, Maree, M, Marero, B, Martinot, ZE, McBride, L, Mesinger, A, Mirocha, J, Molewa, M, Morales, MF, Mosiane, T, Muñoz, JB, Murray, SG, Nagpal, V, Neben, AR, Nikolic, B, Nunhokee, CD, Nuwegeld, H, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Qin, Y, Razavi-Ghods, N, Robnett, J, Rosie, K, Santos, MG, Sims, P, Singh, S, Smith, C, Swarts, H, Tan, J, Thyagarajan, N, Wilensky, MJ, Williams, PKG, Van Wyngaarden, P, Zheng, H, Aguirre, JE [0000-0002-4810-666X], Barkana, R [0000-0002-1557-693X], Beardsley, AP [0000-0001-9428-8233], Bernardi, G [0000-0002-0916-7443], Bowman, JD [0000-0002-8475-2036], Bradley, RF [0000-0003-1172-8331], Breitman, D [0000-0002-2349-3341], Bull, P [0000-0001-5668-3101], Carilli, CL [0000-0001-6647-3861], Choudhuri, S [0000-0002-2338-935X], DeBoer, DR [0000-0003-3197-2294], de Lera Acedo, E [0000-0001-8530-6989], Dillon, JS [0000-0003-3336-9958], Ewall-Wice, A [0000-0002-0086-7363], Fagnoni, N [0000-0001-5300-3166], Fialkov, A [0000-0002-1369-633X], Furlanetto, SR [0000-0002-0658-1243], Gorce, A [0000-0002-1712-737X], Gorthi, D [0000-0002-0829-167X], Greig, B [0000-0002-4085-2094], Hazelton, BJ [0000-0001-7532-645X], Heimersheim, S [0000-0001-9631-4212], Hewitt, JN [0000-0002-4117-570X], Jacobs, DC [0000-0002-0917-2269], Kern, NS [0000-0002-8211-1892], Kerrigan, J [0000-0002-1876-272X], Kittiwisit, P [0000-0003-0953-313X], Kohn, SA [0000-0001-6744-5328], Kolopanis, M [0000-0002-2950-2974], Lanman, A [0000-0003-2116-3573], La Plante, P [0000-0002-4693-0102], Liu, A [0000-0001-6876-0928], Ma, YZ [0000-0001-8108-0986], Mesinger, A [0000-0003-3374-1772], Mirocha, J [0000-0002-8802-5581], Morales, MF [0000-0001-7694-4030], Muñoz, JB [0000-0002-8984-0465], Murray, SG [0000-0003-3059-3823], Nagpal, V [0000-0001-5909-4433], Neben, AR [0000-0001-7776-7240], Nikolic, B [0000-0001-7168-2705], Nunhokee, CD [0000-0002-5445-6586], Parsons, AR [0000-0002-5400-8097], Pascua, R [0000-0003-0073-5528], Patra, N [0000-0002-9457-1941], Qin, Y [0000-0002-4314-1810], Razavi-Ghods, N [0000-0003-2930-5396], Rosie, K [0000-0003-3611-8804], Santos, MG [0000-0003-3892-3073], Sims, P [0000-0002-2871-0413], Singh, S [0000-0001-7755-902X], Tan, J [0000-0001-6161-7037], Thyagarajan, N [0000-0003-1602-7868], Wilensky, MJ [0000-0001-7716-9312], Williams, PKG [0000-0003-3734-3587], Zheng, H [0000-0001-8267-3425], and Apollo - University of Cambridge Repository

Subjects
Space and Planetary Science, 5101 Astronomical Sciences, Astronomy and Astrophysics, 51 Physical Sciences
Abstract

We report the most sensitive upper limits to date on the 21 cm epoch of reionization power spectrum using 94 nights of observing with Phase I of the Hydrogen Epoch of Reionization Array (HERA). Using similar analysis techniques as in previously reported limits, we find at 95% confidence that Δ2(k = 0.34 h Mpc−1) ≤ 457 mK2 at z = 7.9 and that Δ2(k = 0.36 h Mpc−1) ≤ 3496 mK2 at z = 10.4, an improvement by a factor of 2.1 and 2.6, respectively. These limits are mostly consistent with thermal noise over a wide range of k after our data quality cuts, despite performing a relatively conservative analysis designed to minimize signal loss. Our results are validated with both statistical tests on the data and end-to-end pipeline simulations. We also report updated constraints on the astrophysics of reionization and the cosmic dawn. Using multiple independent modeling and inference techniques previously employed by HERA Collaboration, we find that the intergalactic medium must have been heated above the adiabatic cooling limit at least as early as z = 10.4, ruling out a broad set of so-called “cold reionization” scenarios. If this heating is due to high-mass X-ray binaries during the cosmic dawn, as is generally believed, our result’s 99% credible interval excludes the local relationship between soft X-ray luminosity and star formation and thus requires heating driven by evolved low-metallicity stars.

Published
2023

20. Moral and Spiritual Recovery Program (MSRP): A Gender-Responsive Action Addressing the Different Challenges Faced by the Students.

Author

DE TORRES PALANAS, VICTORINA and PALANAS, DEXTER M.

Subjects
*RELIGIOUS behaviors, *APATHY, *VALUES (Ethics), *MATURATION (Psychology), *TIME management, *SEMI-structured interviews, *STUDENTS
Abstract

The current youth landscape in the Philippines is marked by moral ambiguity and apathy towards spiritual and developmental issues. This study delves into the impact of moral and spiritual recovery programs on students at School A. The objective is to address their unique challenges and to identify how the Moral and Spiritual Recovery Program (MSRP) affects individual behavior in terms of Maka-Diyos (Godly), Makatao (Humane), Makakalikasan (Nature Lover), and Makabansa (Patriotic) as perceived by teachers, to determine the themes that emerge from the challenges students face, identify the MSRP contribution to their personal growth, and to determine the program that influences the students' moral and spiritual aspects. Employing a Mixed-Method Research Design utilizing semi-structured interviews with 11 participants and surveys 1,350 participants to explore the role of MSRP in Values Formation at School A. The program transformed the classroom into a space for nurturing self-regulated learners who actively participate, comply with rules, and respect regulations. Three themes drove students' changing priorities. These are family-centeredness, engagement in various activities, and perception of related factors. Key challenges included time management, depression, and self-analysis issues, with coping strategies like faith and religiosity. Students' transformative strategies centered on respect and integrity. Moreover, positive behavioral outcomes were observed not only during the MSRP but also during regular class hours. In conclusion, the study highlights the need to update the MSRP and align it with sustainability goals, addressing criticisms and making it more transparent in its current application. [ABSTRACT FROM AUTHOR]

Published
2023
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21. Health and Safety in the Construction Industry in Catanduanes, Philippines

Author

Dexter M. Toyado

Subjects
Bad habit, Government, Construction industry, business.industry, General Engineering, Public relations, business, Occupational safety and health, Construction site safety
Abstract

The Island Province of Catanduanes is gaining grounds in the field of construction. The program of the current administration “Build, Build, Build” have taken the construction industry to full blast. Construction, both private and public are evident on every corners of the island. Occupational Safety and Health in construction is often neglected and disregarded. Construction is the one of the most dangerous sectors in health and safety. The government, thru the Department of Labor and Employment had already address the problem by providing safety and health training to the personnel of the construction firm as well as the industry as a whole. But the effort has been far from satisfactory, as construction accident continue to dominate the entire industry. The study aims to awareness of construction safety in Catanduanes. The study focuses on the awareness of workers in construction industry in Catanduanes on Occupational Safety and Health. From the series of interviews and interaction with the workers on site, and upon evaluation of their responses, the researcher finally come up with the conclusion that, the construction workers are aware of the safety and health in constructions but they do not adhere and follow it. Workers admittedly that the reason they are complaisant about following safety and health practices are discomfort, beliefs, and bad habits. The following recommendation were sought based on the results of the interview; 1. Workers must attend or be trained with safety and health. A training that would enable them to understand the safety and health issues and concerns, 2. Workers must be taught with correct attitude towards safety in workplace, 3. They must taught of right things contrary to their old beliefs, 4. Workers must developed good habit and positive outlook in terms of their safety and well-being.

Published
2021

22. Why it is so hard to teach people they can make a difference: climate change efficacy as a non-analytic form of reasoning

Author

Cassandra M. Chapman, Dexter M. Oelrichs, and Matthew J. Hornsey

Subjects
Philosophy, Motivated reasoning, 05 social sciences, Climate change, 050109 social psychology, 0501 psychology and cognitive sciences, Experimental and Cognitive Psychology, Psychology (miscellaneous), Psychology, 050105 experimental psychology, Cognitive psychology
Abstract

People who believe they have greater efficacy to address climate change are more likely to engage in pro-environmental behaviour. To confront the climate crisis, it will therefore be essential to u...

Published
2021

23. Direct Optimal Mapping for 21cm Cosmology: A Demonstration with the Hydrogen Epoch of Reionization Array

Author

Xu, Z, Hewitt, JN, Chen, KF, Kim, H, Dillon, JS, Kern, NS, Morales, MF, Hazelton, BJ, Byrne, R, Fagnoni, N, Acedo, EDL, Abdurashidova, Z, Adams, T, Aguirre, JE, Alexander, P, Ali, ZS, Baartman, R, Balfour, Y, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, Eksteen, N, Ely, J, Ewall-Wice, A, Fritz, R, Furlanetto, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hickish, J, Jacobs, DC, Julius, A, Kariseb, M, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, Plante, PL, Liu, A, Loots, A, Ma, YZ, Edward MacMahon, DH, Malan, L, Malgas, C, Malgas, K, Marero, B, Martinot, ZE, Mesinger, A, Molewa, M, Mosiane, T, Murray, SG, Neben, AR, Nikolic, B, Nuwegeld, H, Parsons, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Robnett, J, Rosie, K, Sims, P, Smith, C, Swarts, H, Thyagarajan, N, Wyngaarden, PVV, Williams, PKG, Zheng, H, Xu, Z [0000-0001-5112-2567], Hewitt, JN [0000-0002-4117-570X], Chen, KF [0000-0002-3839-0230], Dillon, JS [0000-0003-3336-9958], Kern, NS [0000-0002-8211-1892], Morales, MF [0000-0001-7694-4030], Hazelton, BJ [0000-0001-7532-645X], Byrne, R [0000-0003-4980-2736], Aguirre, JE [0000-0002-4810-666X], Beardsley, AP [0000-0001-9428-8233], Bernardi, G [0000-0002-0916-7443], Bowman, JD [0000-0002-8475-2036], Bradley, RF [0000-0003-1172-8331], Bull, P [0000-0001-5668-3101], Carilli, CL [0000-0001-6647-3861], DeBoer, DR [0000-0003-3197-2294], Ewall-Wice, A [0000-0002-0086-7363], Furlanetto, SR [0000-0002-0658-1243], Gorthi, D [0000-0002-0829-167X], Greig, B [0000-0002-4085-2094], Jacobs, DC [0000-0002-0917-2269], Kerrigan, J [0000-0002-1876-272X], Kittiwisit, P [0000-0003-0953-313X], Kohn, SA [0000-0001-6744-5328], Kolopanis, M [0000-0002-2950-2974], Lanman, A [0000-0003-2116-3573], Plante, PL [0000-0002-4693-0102], Liu, A [0000-0001-6876-0928], Ma, YZ [0000-0001-8108-0986], Mesinger, A [0000-0003-3374-1772], Murray, SG [0000-0003-3059-3823], Neben, AR [0000-0001-7776-7240], Parsons, AR [0000-0002-5400-8097], Patra, N [0000-0002-9457-1941], Pober, JC [0000-0002-3492-0433], Sims, P [0000-0002-2871-0413], Thyagarajan, N [0000-0003-1602-7868], Williams, PKG [0000-0003-3734-3587], Apollo - University of Cambridge Repository, Xu, Zhilei, Hewitt, Jacqueline N., Chen, Kai-Feng, Kim, Honggeun, Dillon, Joshua S., Kern, Nicholas S., Morales, Miguel F., Hazelton, Bryna J., Byrne, Ruby, Fagnoni, Nicola, de Lera Acedo, Eloy, Abdurashidova, Zara, Adams, Tyrone, Aguirre, James E., Alexander, Paul, Ali, Zaki S., Baartman, Rushelle, Balfour, Yanga, Beardsley, Adam P., Bernardi, Gianni, Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., Bull, Philip, Burba, Jacob, Carey, Steven, Carilli, Chris L., Cheng, Carina, Deboer, David R., Dexter, Matt, Eksteen, Nico, Ely, John, Ewall-Wice, Aaron, Fritz, Randall, Furlanetto, Steven R., Gale-Sides, Kingsley, Glendenning, Brian, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hickish, Jack, Jacobs, Daniel C., Julius, Austin, Kariseb, Maccalvin, Kerrigan, Joshua, Kittiwisit, Piyanat, Kohn, Saul A., Kolopanis, Matthew, Lanman, Adam, La Plante, Paul, Liu, Adrian, Loots, Anita, Ma, Yin-Zhe, Harold Edward MacMahon, David, Malan, Lourence, Malgas, Cresshim, Malgas, Keith, Marero, Bradley, Martinot, Zachary E., Mesinger, ANDREI ALBERT, Molewa, Mathakane, Mosiane, Tshegofalang, Murray, Steven G., Neben, Abraham R., Nikolic, Bojan, Nuwegeld, Han, Parsons, Aaron R., Patra, Nipanjana, Pieterse, Samantha, Pober, Jonathan C., Razavi-Ghods, Nima, Robnett, Jame, Rosie, Kathryn, Sims, Peter, Smith, Craig, Swarts, Hilton, Thyagarajan, Nithyanandan, Van Van Wyngaarden, Pieter, Williams, Peter K. G., and Zheng, Haoxuan

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), model, maps, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galactic radio-emission, 5109 Space Sciences, power spectrum, calibration, 10 mhz, Settore FIS/05 - Astronomia e Astrofisica, 5101 Astronomical Sciences, Space and Planetary Science, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), upper limit, 51 Physical Sciences, 5107 Particle and High Energy Physics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Motivated by the desire for wide-field images with well-defined statistical properties for 21cm cosmology, we implement an optimal mapping pipeline that computes a maximum likelihood estimator for the sky using the interferometric measurement equation. We demonstrate this direct optimal mapping with data from the Hydrogen Epoch of Reionization (HERA) Phase I observations. After validating the pipeline with simulated data, we develop a maximum likelihood figure-of-merit for comparing four sky models at 166MHz with a bandwidth of 100kHz. The HERA data agree with the GLEAM catalogs to, 16 pages, 10 figures, 2 tables, published on ApJ

Published
2022

24. Reliability of Postural Analysis Application Technology (PAAT) as a Measure of Static Standing Posture

Author

Jade Jaime D. Amparo, Er D. Petil, Joreine J. Lalata, John Benedict T. Mabansag, Alexis Anne L. Pascual, and Dexter M. Sotto

Abstract

Aim: To determine the instrument reliability of Postural Application Technology (PAAT) as an assessment tool of static posture. Method: There were sixty participants included in the study. The respondents were obtained using a non-probability convenience sampling technique, Slovin’s Formula was used to compute for the sample size. Data were analyzed using Cronbach Alpha Correlation to measure internal consistency, Interclass correlation Coefficient for external reliability. A scattered plot was use to understand and observed the correlational / relationship between variables. Result: The anterior view (AV) and lateral view (LV) showed high reliability on the shoulder, ankle, torso, and leg assessments (Cronbach’s alpha= 0.80, 0.76, 0.84, 0.84 respectively) and medium reliability on AP head, arms, pelvis assessments (Cronbach’s alpha= 0.50, 0.66, 0.61 respectively), and for LV head tilt (Cronbach’s alpha= 0.64.) For external reliability on AV, data showed excellent reliability on shoulder, pelvis, and ankle assessments (ICC= 0.81,0.77, 0.79) and good reliability on arms (ICC=0.65); and fair reliability on head and knees (ICC= 0.5, 0.46 respectively). With LV, excellent reliability was found on torso and legs (ICC= 0.84, 0.77) respectively) and good reliability on head tilt (ICC=0.64). The scatter plot showed a strong positive linear correlation of the anterior view data with the head, shoulder, pelvis, and ankle. With the lateral view data, the scatter plot showed a strong positive linear correlation with head tilt, and torso, and a weak positive linear correlation with the leg Conclusion and Implication: PAAT is a reliable tool for the assessment that can be used by clinicians, academicians, and students for objective assessment of static posture.

Published
2022

25. Demographic and Academic Trends in Drinking Patterns and Alcohol-Related Problems on Dry College Campuses

Author

Taylor, Dexter M., Johnson, Mark B., and Voas, Robert B.

Abstract

Restricting alcohol consumption on campus is a measure often used by college administrators to prevent alcohol abuse and-alcohol-related problems. The effect of dry campus policies on alcohol consumption and alcohol-related problems, however, remains poorly understood. This report will compare characteristics of two dry campuses with descriptions of general college drinking trends with respect to students' demographic and social/academic characteristics. At two Western universities, 9,073 undergraduates aged 18 and older were surveyed between 2000 and 2004. Drinking and alcohol-related problems found on the dry campuses were similar to national trends on college campuses. Results suggest campus alcohol policies limit drinking on campus but do not prevent previously identified demographic and academic college drinking patterns. (Contains 3 tables and 3 endnotes.)

Published
2006

26. Awareness of Disaster Risk Reduction (DRR) among Student of the Catanduanes State University

Author

Dexter M. Toyado and Dexter M. Toyado

Abstract

The Island Province of Catanduanes is prone to all types of natural hazards that includes torrential and heavy rains, strong winds and surge, flooding and landslide or slope failures as a result of its geographical location and topography. RA 10121 mandates local DRRM bodies to “encourage community, specifically the youth, participation in disaster risk reduction and management activities, such as organizing quick response groups, particularly in identified disaster-prone areas, as well as the inclusion of disaster risk reduction and management programs as part of youth programs and projects. The study aims to determine the awareness to disaster of the student of the Catanduanes State University. The disaster-based questionnaire was prepared and distributed among 636 students selected randomly from different Colleges and Laboratory Schools in the University The Catanduanes State University students understood some disaster-related concepts and ideas, but uncertain on issues on preparedness, adaptation, and awareness on the risks inflicted by these natural hazards. Low perception on disaster risks are evidently observed among students. The responses of the students could be based on the efficiency and impact of the integration of DRR education in the senior high school curriculum. Specifically, integration of the concepts about the hazards, hazard maps, disaster preparedness, awareness, mitigation, prevention, adaptation, and resiliency in the science curriculum possibly affect the knowledge and understanding of students on DRR. Preparedness drills and other forms of capacity building must be done to improve awareness of the student towards DRRM. The study further recommends that teachers and instructor must also be capacitated in handling disaster as they are the prime movers in the implementation of the DRRM in education. Preparedness drills and other forms of capacity building must be done to improve awareness of the student towards DRRM. Core subjects in Earth

Published
2022

27. Automated Detection of Antenna Malfunctions in Large-N Interferometers: A case study With the Hydrogen Epoch of Reionization Array

Author

Storer, D, Dillon, JS, Jacobs, DC, Morales, MF, Hazelton, BJ, Ewall-Wice, A, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Acedo, EL, Dexter, M, Dynes, S, Ely, J, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hewitt, JN, Hickish, J, Huang, T, Josaitis, A, Julius, A, Kariseb, M, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Liu, A, Loots, A, MacMahon, D, Malan, L, Malgas, C, Martinot, ZE, Mesinger, A, Molewa, M, Mosiane, T, Murray, SG, Neben, AR, Nikolic, B, Nunhokee, CD, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Riley, D, Robnett, J, Rosie, K, Santos, MG, Sims, P, Singh, S, Smith, C, Tan, J, Thyagarajan, N, Williams, PKG, Zheng, H, Storer, D, Dillon, JS, Jacobs, DC, Morales, MF, Hazelton, BJ, Ewall-Wice, A, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Acedo, EL, Dexter, M, Dynes, S, Ely, J, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hewitt, JN, Hickish, J, Huang, T, Josaitis, A, Julius, A, Kariseb, M, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Liu, A, Loots, A, MacMahon, D, Malan, L, Malgas, C, Martinot, ZE, Mesinger, A, Molewa, M, Mosiane, T, Murray, SG, Neben, AR, Nikolic, B, Nunhokee, CD, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Riley, D, Robnett, J, Rosie, K, Santos, MG, Sims, P, Singh, S, Smith, C, Tan, J, Thyagarajan, N, Williams, PKG, and Zheng, H

Published
2022

28. Online neutral line fault locator for point-to-point HVdc transmission for line to ground faults

Author

Filizadeh, Shaahin (Electrical and Computer Engineering), Rajapakse, Athula (Electrical and Computer Engineering), Gokaraju, Ramakrishna (University of Saskatchewan), Gole, Aniruddha M., Williams, Dexter M. T. J., Filizadeh, Shaahin (Electrical and Computer Engineering), Rajapakse, Athula (Electrical and Computer Engineering), Gokaraju, Ramakrishna (University of Saskatchewan), Gole, Aniruddha M., and Williams, Dexter M. T. J.

Abstract

High Voltage Direct Current (HVdc) transmission is seeing an increasing use as an efficient method for delivering renewable energy from remote areas to the load center(s). Maintaining the integrity of the HVdc transmission line is paramount to insuring the reliability and the sustainability of the supply. An important component, to this reliability and sustainability, is the rapid detection and repair of faults on the HVdc transmission line. Modern point-to-point HVdc transmission systems utilize a neutral conductor in addition to the power carrying conductors for HVdc power transmission. The voltage of the neutral conductor is normally zero volts since the neutral conductor is grounded at one end. Online dc Line Fault Locator (dcLFL) systems, such as the dcLFL developed by Manitoba Hydro International (MHI), can reliably and rapidly detect the fault location on the main power carrying conductors of an HVdc transmission line. This is accomplished by detecting the arrival time of the traveling wave from the voltage at the station. However, the low voltage on the neutral conductor prevents the dcLFL from detecting fault locations on the neutral conductor. The objective of this research is to design and implement a suitable method for reliably and rapidly detecting and locating faults on the neutral conductor. An online Neutral Line Fault Locator (nLFL) system which uses HVdc system measurements with regression analysis to derive the transmission line impedance to determine an accurate fault location is proposed. To surmount the low-voltage problem. The proposed nLFL system was developed and tested, with a highly detailed Electromagnetic Transients (EMT) simulation model. The nLFL system was constructed in hardware and tested in real time using a real-time EMT simulator. After detailed EMT studies of various scenarios, the nLFL system was field tested on the East Alberta Transmission Line (EATL) HVdc system.

Published
2022

29. Trends of Rainfall Pattern in the Island Province of Catanduanes, Philippines

Author

Engr. Dexter M. Toyado, MM and Engr. Dexter M. Toyado, MM

Abstract

The Island of Catanduanes is located in the eastern most fringe of Luzon considered to be the doorstep of typhoon path. The rainfall in the province is important in producing agricultural food to make life in the province sustainable. Hence, it is necessary to establish how the effect of climate change variable on the availability of water in the island, so that impending extreme drought or flooding will be mitigated. In addition to that, Climate change in the island has an impact on human activity, and  a treat from flooding  of variable weather pattern like seasonal monsoon rain and inter tropical convergence zone develop near the island. Using the data from the PAGASA-DOST, Climatology and Agro meteorology Division (CAD) of April 2020, from the Virac Doppler and Radar Weather in Catanduanes. Synoptic data were used to evaluate the rainfall for the last 30 years.  The rainfall pattern caused by the southwest monsoon (Habagat) most from June to September gives an average of 73.08mm for 3 decades. Northeast monsoon (Amihan) usually arrives on November and ends on March having an average rainfall of 103.78mm for 3 decades. It has been shown that the rainfall is increasing every year, the annual rainfall trends will increase of up to 10.76mm in the next 10 years. Studying the rainfall pattern and temperature will give us more precise assessment of the climatic condition in the island and give the community and the government the proper information for mitigating and planning on how we can handle climate change.

Published
2022

30. Adolescent Suicidality: Who Will Ideate, Who Will Act?

Author

Miller, Ted R. and Taylor, Dexter M.

Abstract

Responses to the 1999 Youth Risk Behavior Survey including suicide ideation, attempt, medically treated attempt, and six problem behaviors were analyzed. Youth across the spectrum ideated. Overwhelmingly, the 17% of youth with more than three problem behaviors were the youth who acted; they accounted for 60% of medically treated suicidal acts. Compared to adolescents with zero problem behaviors, the odds of a medically treated suicide attempt were 2.3 times greater among respondents with one, 8.8 with two, 18.3 with three, 30.8 with four, 50.0 with five, and 227.3 with six. A count of problem behaviors offers a reliable way to identify suicide risk.

Published
2005
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32. Disaster Preparedness of Local Government Units Communication Systems in Catanduanes, Philippines

Author

Dexter M. Toyado

Subjects
Disaster risk reduction, Warning system, business.industry, Software deployment, Local government, The Internet, Information needs, business, Communications system, Telecommunications, Dissemination
Abstract

This study assesses the communication capabilities of the Local Government Unit (LGU) of Catanduanes and to develop findings on the current communication systems that will address the information needs of their constituents more particularly when the usual communications fails during the times of disasters. All Municipal Disaster Risk Reduction Management Office (MDRRMO) uses the small messaging system (SMS) or cellular phones in gathering and disseminating disaster-related information. A handful of MDRRMO do not use VHF Radio and all of them use early warning systems to disseminate information to their respective communities. The transmission and receiving of disaster-related information are being acquired through cellular phones. The study concludes the inadequacy in the LGU Communications System Facilities and the readiness for deployment in case of the strong typhoon on the province when the existing communication facilities are disrupted, particularly the Internet and SMS technologies. Some municipalities have not identified what communications systems to use in case there is a total communication failure during disasters. Some municipalities will request the services of Amateur Radio for assistance. Some will request private radio users to relay information in case normal communication fails. Some Municipalities have not invested in or allocated a budget for communications systems facilities. Finally, this study recommends that an annual budget for the communications system must be restored under the MDRRMO to ensure the serviceability of existing communications facilities and equipment. And equip the LGU with the low cost and modest communication facilities to respond in times of disaster.

Published
2020

33. Comparative Analysis of Directional Antenna of 2-Meter Amateur Band for Ham Radio Applications

Author

Dexter M. Toyado

Subjects
Software, Directional antenna, business.industry, Computer science, Electrical engineering, Metre, Antenna (radio), business, Electrical impedance, Boom
Abstract

VHF Directional Antenna is not easily found in the Philippine market. Supplies of this kind of antenna are expensive that can only be purchased directly from the manufacturers. Ham Radio operators usually build, modify, and perform experimentation on the directional antenna to achieve higher dB gain for DXing activities. In this study, we use the 3- effective directional antenna for comparability analysis. Its performance is needed in long-range communication of 2-meter amateur band application. The 4NEC2 software was used to simulate the radiating pattern and other properties of each directional antenna. Simulation of the antenna with 3, 7, and 13 elements resulted in substantial proof, describing the better usage of the loop feed-in directional antenna system. It would result in a higher dB gain with longer antenna boom length. However, the MOX-GI design is comparable to a Yagi-Uda directional antenna in both boom length, and dB gain. MOX-GI antenna exhibits good impedance and lowers SWR reading which is desirable for easy home brewing directional antenna.

Published
2020

36. Motivation of Engineering Faculty of the Catanduanes State University Toward works

Author

Dexter M. Toyado

Subjects
Medical education, Work abroad, Work (electrical), Engineering education, media_common.quotation_subject, General Engineering, Institution, Employee motivation, Salary, Psychology, Reputation, media_common, Qualitative research
Abstract

The graduates of the Catanduanes State University prefer to work abroad and in Metro Manila. There were some who preferred to stay in the province and look for a job. The College of Engineering barely needs additional faculty members, but few are willing to work in the institution. This research sought to determine the unique motivational factors towards work of the faculty of the college and why they are staying in the university. The research was conducted using a qualitative study of the faculty utilizing the questionnaire and interview on the motivation aspect towards work. The faculty of Catanduanes State University- College of Engineering was found to be significantly interested in doing their best and, given the freedom, will perform well. Simple recognition will validate what they have done well and will serve as additional motivation for the faculty. This research also found that organization background, reputation, working environment, harmonious workplace relationship is equally important with the salary.

Published
2021

38. Corrosion Behavior of AA 1100 Anodized in Gallic-Sulfuric Acid Solution

Author

Jayson S. Garcia, Dexter M. Manguerra, Cyril John C. Narisma, and Marlon L. Mopon

Subjects
inorganic chemicals, Materials science, aluminum anodization, Scanning electron microscope, 020209 energy, chemistry.chemical_element, 02 engineering and technology, Electrolyte, electrolyte, Corrosion, chemistry.chemical_compound, Aluminium, 0202 electrical engineering, electronic engineering, information engineering, Materials Chemistry, Gallic acid, corrosion resistance, Anodizing, Sulfuric acid, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Surfaces, Coatings and Films, Dielectric spectroscopy, electrochemical impedance spectroscopy, chemistry, lcsh:TA1-2040, gallic acid, 0210 nano-technology, lcsh:Engineering (General). Civil engineering (General), Nuclear chemistry
Abstract

Sulfuric acid anodization is one of the common methods used to improve corrosion resistance of aluminum alloys. Organic acids can be added to the sulfuric acid electrolyte in order to improve the properties of the anodized aluminum produced. In this study, the use of gallic acid as an additive to the sulfuric acid anodization of AA1100 was explored. The effect of varying anodization current density and gallic acid concentration on the properties of anodized aluminum samples was observed using electrochemical impedance spectroscopy, linear polarization, and scanning electron microscopy. It was observed that the corrosion resistance of samples anodized in gallic-sulfuric acid solution at 10 mA·cm−2 is lower than samples anodized in sulfuric acid. It was also observed that higher anodization current density can lead to lower corrosion resistances for aluminum samples anodized in gallic-sulfuric acid solution. However, samples anodized at 5 mA·cm−2 and at a gallic acid concentration of 5 g·L−1 showed better corrosion performance than the samples anodized in sulfuric acid only. This suggests that the use of low amounts of gallic acid as an additive for sulfuric acid anodization can lead to better corrosion resistances for anodized aluminum.

Published
2021

39. Why it is so hard to teach people they can make a difference: climate change efficacy as a non-analytic form of reasoning.

Author

Hornsey, Matthew J., Chapman, Cassandra M., and Oelrichs, Dexter M.

Subjects
CLIMATE change, GREEN movement, SOCIAL desirability, SOCIAL norms
Abstract

People who believe they have greater efficacy to address climate change are more likely to engage in pro-environmental behaviour. To confront the climate crisis, it will therefore be essential to understand the processes through which climate change efficacy is promoted. Some interventions in the literature assume that efficacy emerges from analytic reasoning processes: that it is deliberative, verbal, conscious, and influenced by information and education. In the current paper, we critique this notion. We review evidence showing that climate change efficacy perceptions are (a) associated with climate-related distress and threat, (b) prescribed by social norms, (c) associated with social desirability and identity-expressive concerns, (d) surprisingly difficult to change through explicit, verbal instruction, but (e) responsive to imagery. We conclude by examining applied implications of these five propositions and discuss why non-analytic processes might (ironically) be beneficial for sustaining green activism. [ABSTRACT FROM AUTHOR]

Published
2022
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42. Discussion

Author

Teaf,, Howard M., Bye, Raymond T., and Keezer, Dexter M.

Published
1961

43. Round Table Conference on the Market for Economists: Demand and Supply Aspects

Author

Bell, James Washington, Woodworth, Robert T., Clague, Ewan, Robinson, Mary Electa, Levine, Louis, Wallis, Allen, Wassen, D. E., Robertson, Jack, Boddy, F. M., Allen, H. K., Keezer, Dexter M., Gainsbrugh, Martin, Arthur, Henry, Schmidt, Emerson P., Hadley, W. E., Vaughn, Jack, Sherry, Leonard, Petshek, Kirk, Levine, Louis, Taylor, Ancel N., Schultz, T. W., Blough, Roy, Phillips, W. T., Hoadley,, W. E., Corson, Louis D., Gitlow, A. L., Wellemayer, J. Fletcher, Kaplan, A. D. H., Higgins, Benjamin, Somers, Gerald, and Harris, Seymour

Published
1959

44. The Proposed Publication of a Periodic Review of Economics

Author

Burns, Eveline M., Spengler, Joseph J., Mason, Edward S., Wallace, Donald H., Copeland, Morris A., Homan, Paul T., Machlup, Fritz, Davis, Joseph S., Knight, Frank H., Mills, Frederick C., Goldenweiser, E. A., Leavens, Dickson H., Wickens, Aryness J., Keezer, Dexter M., Harris, Seymour E., Buchanan, Norman S., Wolfe, Albert B., Backman, Jules, and Chamberlin, Edward

Published
1946

45. Discussion

Author

Northrup, Herbert R., Keezer, Dexter M., Anrod, Charles W., Starr, Mark, and Reynolds, LLoyd G.

Published
1946

50. Effects of model incompleteness on the drift-scan calibration of radio telescopes

Author

Gehlot, BK, Jacobs, DC, Bowman, JD, Mahesh, N, Murray, SG, Kolopanis, M, Beardsley, AP, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Bernardi, G, Billings, TS, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, Acedo, EDL, Dillon, JS, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Julius, A, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Lanman, A, La Plante, P, Lekalake, T, Lewis, D, Liu, A, Ma, Y-Z, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Monsalve, RA, Morales, MF, Mosiane, T, Neben, AR, Nikolic, B, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Santos, MG, Sims, P, Smith, C, Syce, A, Tegmark, M, Thyagarajan, N, Williams, PKG, Zheng, H, Gehlot, BK, Jacobs, DC, Bowman, JD, Mahesh, N, Murray, SG, Kolopanis, M, Beardsley, AP, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Bernardi, G, Billings, TS, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, Acedo, EDL, Dillon, JS, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Julius, A, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Lanman, A, La Plante, P, Lekalake, T, Lewis, D, Liu, A, Ma, Y-Z, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Monsalve, RA, Morales, MF, Mosiane, T, Neben, AR, Nikolic, B, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Santos, MG, Sims, P, Smith, C, Syce, A, Tegmark, M, Thyagarajan, N, Williams, PKG, and Zheng, H

Abstract

Precision calibration poses challenges to experiments probing the redshifted 21-cm signal of neutral hydrogen from the Cosmic Dawn and Epoch of Reionization (z ∼ 30–6). In both interferometric and global signal experiments, systematic calibration is the leading source of error. Though many aspects of calibration have been studied, the overlap between the two types of instruments has received less attention. We investigate the sky based calibration of total power measurements with a HERA dish and an EDGES-style antenna to understand the role of autocorrelations in the calibration of an interferometer and the role of sky in calibrating a total power instrument. Using simulations we study various scenarios such as time variable gain, incomplete sky calibration model, and primary beam model. We find that temporal gain drifts, sky model incompleteness, and beam inaccuracies cause biases in the receiver gain amplitude and the receiver temperature estimates. In some cases, these biases mix spectral structure between beam and sky resulting in spectrally variable gain errors. Applying the calibration method to the HERA and EDGES data, we find good agreement with calibration via the more standard methods. Although instrumental gains are consistent with beam and sky errors similar in scale to those simulated, the receiver temperatures show significant deviations from expected values. While we show that it is possible to partially mitigate biases due to model inaccuracies by incorporating a time-dependent gain model in calibration, the resulting errors on calibration products are larger and more correlated. Completely addressing these biases will require more accurate sky and primary beam models.

Published
2021

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