5,332 research outputs found
The Galactic cosmic-ray Sun shadow observed by HAWC
The magnetic field of the Solar corona is difficult to measure directly.
However, indirect observations of the solar corona are possible using the
deficit in flux of cosmic rays coming from the direction of the Sun. Low-energy
cosmic rays (~GeV) are deflected by the inner magnetic field of the Sun and the
interplanetary magnetic field frozen into the solar wind. In contrast,
high-energy cosmic rays (~TeV and above) are absorbed in the Sun's photosphere
producing a shadow in the Sun's nominal position viewed from Earth. Several
ground-based instruments have observed the effects of the heliospheric magnetic
field on the size of the sun shadow and its position. The High-Altitude Water
Cherenkov Observatory (HAWC) is an air shower array located in the central
region of Mexico that observes TeV cosmic rays at a rate of about 15 kHz. in
this work, we present preliminary images of the sun shadow from data collected
by HAWC during 2013 and 2014 for different energy ranges.Comment: Presented at the 34th International Cosmic Ray Conference (ICRC2015),
The Hague, The Netherlands. See arXiv:1508.03327 for all HAWC contribution
Comparison between flying capacitor and modular multilevel inverter
The paper describes the operational principle of flying capacitor and modular multilevel inverters. The detailed discussions of dc link capacitors voltage balancing methods for both inverters are given in order to enable fair comparison. The causes of dc link capacitors voltage imbalance in flying capacitor multilevel inverter with more than three levels are highlighted. Computer simulation is used to compare the performance of both inverters under several operating conditions
Comparison between two VSC-HVDC transmission systems technologies : modular and neutral point clamped multilevel converter
The paper presents a detail comparison between two voltage source converter high voltage dc transmission systems, the first is based on neutral point-clamped (also known as HVDC-Light) and the second is based on innovative modular multilevel converter (known as HVDC-Plus). The comparison focuses on the reliability issues of both technologies such as fault ride-through capability and control flexibility. To address these issues, neutral point-clamped and three-level modular converters are considered in both stations of the dc transmission system, and several operating conditions are considered, including, symmetrical and asymmetrical faults. Computer simulation in Matlab-Simulink environment has been used to confirm the validity of the results
The determination of pre-impact speeds and accident scene information using PhotoModeler as a measurement tool
This thesis investigates the role of PhotoModeler, a photogrammetry technique, in traffic accident reconstruction. More specifically, important elements to the reconstructionist such as vehicle crush and accident scene details are measured with PhotoModeler. The extracted measurements are utilized further to establish pre-impact speeds and vehicle placement in terms of the centerline.
To verify that PhotoModeler is a suitable measurement technique, its results are compared against NTSHA controlled crash data and a pre-measured accident scene.
The data are convincing. NTSHA\u27s crash tests are performed at 35 mph and this study\u27s results came up with 36.88 mph, which is quite good. In the accident scene diagram, the average measurement deviation was 1.480 inches, which is also a good result.
PhotoModeler is accurate as well as convenient for generating measurements when applied to traffic accident reconstruction situations
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Ethics and Design in the Brazilian Context
Often driven by practical and immediate requirements, more and more people are incorporating technology into a variety of aspects of their lives, often without reflecting on the consequences of using them. On the other hand, studies on interactive system development that lead to behavioral change have been gaining ground on the agenda of large HCI conferences. This movement brings to the forefront the fundamental issues of ethics in design and technology use. A designer’s intentions, when directing certain actions or behaviors, are not always explicit or desired by the stakeholders affected by the use of the technology. Systems that induce an undesired purchase, or even those that use conditioning strategies to cause a behavioral change are examples of such intentions. The challenge proposed is therefore about the relationship between design and personal freedom in a way that these technology users do not become victims, either passively or submissively, of the effects of its use. This advance allows for the redefinition of the relationship between man and technology, and the application of new forms of designing and developing interactive systems that take into account the ethical aspects of this relationship
Controllable Neural Story Plot Generation via Reinforcement Learning
Language-modeling--based approaches to story plot generation attempt to
construct a plot by sampling from a language model (LM) to predict the next
character, word, or sentence to add to the story. LM techniques lack the
ability to receive guidance from the user to achieve a specific goal, resulting
in stories that don't have a clear sense of progression and lack coherence. We
present a reward-shaping technique that analyzes a story corpus and produces
intermediate rewards that are backpropagated into a pre-trained LM in order to
guide the model towards a given goal. Automated evaluations show our technique
can create a model that generates story plots which consistently achieve a
specified goal. Human-subject studies show that the generated stories have more
plausible event ordering than baseline plot generation techniques.Comment: Published in IJCAI 201
Provision of frequency support by offshore wind farms connected via HVDC links
The high penetration levels of wind power will obligate wind farms to contribute to the mitigation of frequency drops. Comprehensive case studies are presented to investigate the different methods of frequency support provision by wind power. The implemented test system is composed of an offshore wind farm connected to an external grid through a point-to-point HVDC link. Three different frequency support methods are compared; droop de-loading, battery storage banks and a mix between the two methods. Moreover, two different methods of sensing the frequency drop, at the point of common coupling, by the wind farm are examined. The impact of the HVDC is highlighted, especially its role to transmit the power surge provided by the wind farm. A modified de-loading controller is developed and integrated to all the wind turbines, according to the executed case studies. Results show that the proposed frequency support solutions have almost similar impact on the natural frequency response at the point of common coupling. The HVDC link does not worsen the frequency response, and the fluctuations in voltage levels at onshore and offshore buses are very minor. DIGsILENT PowerFactory is integrated as a simulation environment
Intranasal melanoma treated with radiation therapy in three dogs
Three dogs were investigated for chronic unilateral nasal discharge. In all cases CT imaging showed an intranasal mass causing turbinate lysis and no evidence of metastasis. Cytology in cases 1 (a 14-year-old neutered male crossbreed dog) and 2 (a five-year-old neutered male German Shepherd dog) demonstrated a pleomorphic cell population with variable intracellular pigment suspicious of melanocytic neoplasia. Histopathology with immunohistochemistry (Melan-A and vimentin, plus PNL-2 in one case) confirmed the diagnosis of melanoma in all dogs. All dogs were treated with megavoltage radiotherapy using linear accelerators. Cases 1 and 3 (a nine-year-old neutered female beagle dog) received a hypofractionated (4 Ă— 8 Gy) protocol and case 2 received a definitive (12 Ă— 4 Gy) protocol. Complete remission was demonstrated on repeat CT scan five months after diagnosis in case 1 and seven months in case 2. Stable disease was documented on CT at four months for case 3; however, clinical signs in this dog remained controlled for 10 months in total. Case 1 died of unrelated causes five months after diagnosis, case 2 was euthanased due to the development of seizures 13 months after diagnosis, and case 3 was lost to follow-up 12 months after diagnosis. Melanoma should be considered as a rare differential diagnosis for primary nasal neoplasia in the dog and radiation therapy can be used as effective local therapy
Bioethics reflection about lung transplant
IndexaciĂłn: ScieloA pesar de los avances que ha experimentado la tĂ©cnica de los trasplantes de Ăłrganos y la mejora en manejo del rechazo, en nuestro paĂs no se advierte un crecimiento adecuado a las necesidades de los trasplantes del sistema respiratorio requeridos. Si bien existen indicaciones precisas de trasplante pulmonar, el problema de la escasez de donantes es una dificultad concreta para los enfermos. Se revisa y compara nuestra situaciĂłn con la de España y se analizan algunos aspectos bioĂ©ticos que surgen de este proceso.Despite a substantial improvement in organ transplant techniques and rejections methods, Chile still exhibits an apparent lack of adequate increase of lung transplants. In particular, despite the presence of precise indicactions of lung transplant, the problem of limited donors is a very difficult reality for the receptors. In this work, we offer a comparison amongst Chile and Spain, with special emphasis on bioethical aspects of this process.http://www.scielo.cl/pdf/rcher/v30n4/art05.pd
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