Providing equivalent learning activities with software-based remote access laboratories

Laboratory-based learning activities are important components of engineering and surveying education and it is difficult to offering practical activities to distance education students. Remote Access Laboratory (RAL) systems are widely discussed as learning tools to offer students remote access to rigs or hardware. In some disciplines laboratory activities are purely software based and RAL systems can be used to provide access to software. As part of a larger study into the transferability of the remote laboratory concept to non-engineering disciplines this project evaluates the effectiveness of RAL based software activities in supporting student learning is investigated. In the discipline of Surveying and Spatial Science, RAL technology is used to provide Geographic Information System software access to distance students. The key research question discussed in this paper is whether RALbased software activities can address the same learning outcomes as face-to-face practical classes for software activities. Data was collected from students' discussion forums, teaching staff diaries and teaching staff interviews. The project demonstrates that students undertaking learning activities remotely achieve similar learning outcomes than student in practice classes using the same software. Ease of system access and usability are critical and the learning activity needs to be supported by comprehensive learning materials. This research provides a clear case in which the use of RAL technology has provided inclusive educational opportunities more efficiently and these general results are also applicable to experiments that involve physical hardware

Optimization of molybdenite flotation using response surface method

Purpose. The paper is aimed to study the molybdenite flotation from a low-grade uranium ore containing 0.2% of Mo. Methods. Three control parameters including frother (MIBC) dosage, collector (gasoline) dosage and pH, each in five levels, were investigated. Response surface methodology (RSM) was performed for statistical design and analysis of experiments and process modeling. Four quadratic mathematical models were derived for prediction of Mo recovery and Mo grade. Findings. Analysis of variance showed that frother and collector dosage were the most significant factors affecting Mo recovery and grade. In process optimization, maximum values of Mo recovery and grade were achieved as 79.13% and 2.93%, respectively. Optimum frother concentration of 78.93 g/t, gasoline dosage of 507.70 g/t, and pH of 9.77, for Mo recovery were obtained. However, in optimization studies, a case proposed the model in which the same consumption of reagents is used. Originality. There is a recognized need for type of uranium ore which contains Molybdenite, therefore working on molybdenite removing from this ore helps to recover uranium in the next steps. This research provides a novel approach to gain the optimum recovery and grade to extract uranium so easily. Practical implications. This study showed that response surface methodology could be effectively used for flotation process modeling as well as finding an optimum condition to achieve maximum recovery and grade under minimum consumption of flotation reagents.Мета. Дослідження особливостей процесу флотації молібденіту з низькозбагаченої уранової руди, що містить 0.2% молібдену. Методика. Проаналізовано три контрольних параметра флотації – дозу спінювача (метил-ізобутил-карбінол), колекторне (газолінове) дозування і ph (кожен – у п’яти різницях рівнів). Для статистичного розрахунку, аналізу експериментів і моделювання процесу флотації застосовано метод поверхневого відклику (МПВ). Були розроблені чотири квадратичні математичні моделі для розрахункових даних отримання Мо і визначення його якості. Результати. Встановлено, що спінювач і колекторне дозування є найбільш впливовими факторами при отриманні Мо та його якості. У процесі оптимізації максимальні рівні отримання Мо та якості були, відповідно, 79.13% і 2.93%. Виявлено наступну оптимальну концентрацію для Мо: спінювач – 78.93 г/т, газолінове дозування – 507.70 г/т, pH – 9.7, що підтверджено моделюванням. Наукова новизна. Запропоновано інноваційний підхід для отримання легкого й оптимального способу відновлення і ступеня вилучення урану до високої якості. Практична значимість. Метод поверхневого відклику може ефективно застосовуватися для моделювання процесу флотації з метою визначення оптимальних умов досягнення максимальної рекуперації та якості при мінімальних витратах флотаційних реагентів.Цель. Исследование особенностей процесса флотации молибденита из низкообогащенной урановой руды, содержащей 0.2% молибдена. Методика. Проанализированы три контрольных параметра флотации – доза вспенивателя (метил-изобутил-карбинол), коллекторная (газолиновая) дозировка и pH (каждый – в пяти разностях уровней). Для статистического расчета, анализа экспериментов и моделирования процесса флотации применен метод поверхности отклика (МПО). Были разработаны четыре квадратичные математические модели для расчетных данных получения Мо и определения его качества. Результаты. Установлено, что вспениватель и коллекторная дозировка являются наиболее влияющими факторами при получении Мо и его качества. В процессе оптимизации максимальные уровни получения Мо и качества были, соответственно, 79.13% и 2.93%. Выявлена следующая оптимальная концентрация для Мо: вспениватель – 78.93 г/т, газолиновая дозировка – 507.70 г/т, pH – 9.7, что подтвержденно моделированием. Научная новизна. Предложен инновационный подход для получения легкого и оптимального способа восстановления и степени извлечения урана до высокого качества. Практическая значимость. Метод поверхностного отклика может эффективно применяться для моделирования процесса флотации с целью определения оптимальных условий достижения максимальной рекуперации и качества при минимальном расходе флотационных реагентов.The financial support of the Jaber Ibn Hayan Research Laboratories, Nuclear Science and Technology Research Institute and Mr. Hasan Sedighi helps and the university of Imam Khomeini (IKIU) is gratefully acknowledged

Strong Coordination over Noisy Channels: Is Separation Sufficient?

We study the problem of strong coordination of actions of two agents $X$ and $Y$ that communicate over a noisy communication channel such that the actions follow a given joint probability distribution. We propose two novel schemes for this noisy strong coordination problem, and derive inner bounds for the underlying strong coordination capacity region. The first scheme is a joint coordination-channel coding scheme that utilizes the randomness provided by the communication channel to reduce the local randomness required in generating the action sequence at agent $Y$. The second scheme exploits separate coordination and channel coding where local randomness is extracted from the channel after decoding. Finally, we present an example in which the joint scheme is able to outperform the separate scheme in terms of coordination rate.Comment: 9 pages, 4 figures. An extended version of a paper accepted for the IEEE International Symposium on Information Theory (ISIT), 201

Strong Coordination over Noisy Channels: Is Separation Sufficient?

We study the problem of strong coordination of actions of two agents $X$ and $Y$ that communicate over a noisy communication channel such that the actions follow a given joint probability distribution. We propose two novel schemes for this noisy strong coordination problem, and derive inner bounds for the underlying strong coordination capacity region. The first scheme is a joint coordination-channel coding scheme that utilizes the randomness provided by the communication channel to reduce the local randomness required in generating the action sequence at agent $Y$. The second scheme exploits separate coordination and channel coding where local randomness is extracted from the channel after decoding. Finally, we present an example in which the joint scheme is able to outperform the separate scheme in terms of coordination rate.Comment: 9 pages, 4 figures. An extended version of a paper accepted for the IEEE International Symposium on Information Theory (ISIT), 201

Coding Schemes for Achieving Strong Secrecy at Negligible Cost

We study the problem of achieving strong secrecy over wiretap channels at negligible cost, in the sense of maintaining the overall communication rate of the same channel without secrecy constraints. Specifically, we propose and analyze two source-channel coding architectures, in which secrecy is achieved by multiplexing public and confidential messages. In both cases, our main contribution is to show that secrecy can be achieved without compromising communication rate and by requiring only randomness of asymptotically vanishing rate. Our first source-channel coding architecture relies on a modified wiretap channel code, in which randomization is performed using the output of a source code. In contrast, our second architecture relies on a standard wiretap code combined with a modified source code termed uniform compression code, in which a small shared secret seed is used to enhance the uniformity of the source code output. We carry out a detailed analysis of uniform compression codes and characterize the optimal size of the shared seed.Comment: 15 pages, two-column, 5 figures, accepted to IEEE Transactions on Information Theor

Distorted Black Holes with Charge

We present new solutions to the Einstein-Maxwell equations representing a class of charged distorted black holes. These solutions are static-axisymmetric and are generalizations of the distorted black hole solutions studied by Geroch and Hartle. Physically, they represent a charged black hole distorted by external matter fields. We discuss the zeroth and first law for these black holes. The first law is proved in two different forms, one motivated by the isolated horizon framework and the other using normalizations at infinity.Comment: 18 pages, LaTe

Trellis-Based Equalization for Sparse ISI Channels Revisited

Sparse intersymbol-interference (ISI) channels are encountered in a variety of high-data-rate communication systems. Such channels have a large channel memory length, but only a small number of significant channel coefficients. In this paper, trellis-based equalization of sparse ISI channels is revisited. Due to the large channel memory length, the complexity of maximum-likelihood detection, e.g., by means of the Viterbi algorithm (VA), is normally prohibitive. In the first part of the paper, a unified framework based on factor graphs is presented for complexity reduction without loss of optimality. In this new context, two known reduced-complexity algorithms for sparse ISI channels are recapitulated: The multi-trellis VA (M-VA) and the parallel-trellis VA (P-VA). It is shown that the M-VA, although claimed, does not lead to a reduced computational complexity. The P-VA, on the other hand, leads to a significant complexity reduction, but can only be applied for a certain class of sparse channels. In the second part of the paper, a unified approach is investigated to tackle general sparse channels: It is shown that the use of a linear filter at the receiver renders the application of standard reduced-state trellis-based equalizer algorithms feasible, without significant loss of optimality. Numerical results verify the efficiency of the proposed receiver structure.Comment: To be presented at the 2005 IEEE Int. Symp. Inform. Theory (ISIT 2005), September 4-9, 2005, Adelaide, Australi

Quasi-Local Linear Momentum in Black-Hole Binaries

We propose a quasi-local formula for the linear momentum of black-hole horizons inspired by the formalism of quasi-local horizons. We test this formula using two complementary configurations: (i) by calculating the large orbital linear momentum of the two black holes in an unequal-mass, zero-spin, quasi-circular binary and (ii) by calculating the very small recoil momentum imparted to the remnant of the head-on collision of an equal-mass, anti-aligned-spin binary. We obtain results consistent with the horizon trajectory in the orbiting case, and consistent with the net radiated linear momentum for the much smaller head-on recoil velocity.Comment: 5 pages, 3 figures, revtex

Non-symmetric trapped surfaces in the Schwarzschild and Vaidya spacetimes

Marginally trapped surfaces (MTSs) are commonly used in numerical relativity to locate black holes. For dynamical black holes, it is not known generally if this procedure is sufficiently reliable. Even for Schwarzschild black holes, Wald and Iyer constructed foliations which come arbitrarily close to the singularity but do not contain any MTSs. In this paper, we review the Wald-Iyer construction, discuss some implications for numerical relativity, and generalize to the well known Vaidya spacetime describing spherically symmetric collapse of null dust. In the Vaidya spacetime, we numerically locate non-spherically symmetric trapped surfaces which extend outside the standard spherically symmetric trapping horizon. This shows that MTSs are common in this spacetime and that the event horizon is the most likely candidate for the boundary of the trapped region.Comment: 4 pages, 3 figures; v2: minor modifications; v3: clarified conclusion