11,524 research outputs found

    A Holistic Education Approach for Assessing Business Programs

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    Providing business students with a holistic education is essential for developing professionals who are equally proficient in their use of hard and soft skills and capable of applying various concepts from different disciplines to create innovative solutions. To understand if students are learning the content that a holistic business education is intended to deliver, a case study of business program assessment was conducted. Specifically, this research is focused on an assessment of business students from a comprehensive regional institution of higher education to determine if the business program has incorporated appropriate assessment strategies in order to meet the expectations of a holistic education including meeting student learning outcomes defined by the AACSB International accredited program

    Ab initio study of the formation of transparent carbon under pressure

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    A body-centered tetragonal carbon (bct-Carbon) allotrope has been predicted to be a transparent carbon polymorph obtained under pressure. The structural transition pathways from graphite to diamond, M-Carbon, and bct-Carbon are simulated and the lowest activation barrier is found for the graphite-bct transition. Furthermore, bct-Carbon has higher shear strength than diamond due to its perpendicular graphene-like structure. Our results provide a possible explanation for the formation of a transparent carbon allotrope via the cold compression of graphite. We also verify that this allotrope is hard enough to crack diamond.Comment: [email protected] or [email protected]

    Model Predictive Control for Dual Active Bridge in Naval DC Microgrids Supplying Pulsed Power Loads Featuring Fast Transition and Online Transformer Current Minimization

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    Pulsed power loads (PPLs) are commonly incorporated in medium voltage dc microgrids on naval vessels. To mitigate their detrimental effects, dedicated energy storage systems can be installed and their converters need to have excellent disturbance rejection capability. To facilitate this objective, a moving-discretized-control-set model-predictive-control (MDCS-MPC) is proposed in this letter and applied on a dual-active-bridge converter. Fixed switching frequency is maintained, enabling easy passive components design. The proposed MDCS-MPC has a small number of calculating points in each switching period, which enables the implementation in standard commercial control platforms. The operating principle of the MDCS-MPC is introduced in development of a cost function that, on one hand, provides stiff voltage regulation; on the other hand, minimizes transformer current stress online. Theoretical claims are verified on a 20 kHz 1 kW dual active bridge

    Berry phase correction to electron density of states in solids

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    Liouville's theorem on the conservation of phase space volume is violated by Berry phase in the semiclassical dynamics of Bloch electrons. This leads to a modification of the phase space density of states, whose significance is discussed in a number of examples: field modification of the Fermi-sea volume, connection to the anomalous Hall effect, and a general formula for orbital magnetization. The effective quantum mechanics of Bloch electrons is also sketched, where the modified density of states plays an essential role.Comment: Minor revision. Journal info updat

    Model-Predictive-Control for Dual-Active-Bridge Converters Supplying Pulsed Power Loads in Naval DC Micro-grids

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    Pulsed-Power-Loads (PPLs) are becoming prevalent in medium-voltage naval DC micro-grids. To alleviate their effects on the system, energy storages are commonly installed. For optimal performance, their interface converters need to have fast dynamics and excellent disturbance rejection capability. Moreover, these converters often need to have voltage transformation and galvanic isolation capability since common energy storage technologies like batteries and super-caps are typically assembled with low voltage strings. In order to address these issues, a Moving-Discretized-Control-Set Model-Predictive-Control (MDCS-MPC) is proposed in this paper and applied on a Dual-Active-Bridge converter. Fixed switching frequency is maintained, enabling easy passive components design. The proposed MDCS-MPC has a reduced prediction horizon, which allows low computational burden. The operating principle of the MDCS-MPC is introduced in development of a cost function that provides stiff voltage regulation. Resonance damping and sampling noise resistance can also be achieved with the proposed cost function. An adaptive step is introduced to enable fast transition. Assessments on the performance of the proposed MDCS-MPC are conducted. Comparisons with other control methods are also provided. Experimental validations on a 300V/300V 20kHz 1kW Dual-Active-Bridge converter are carried out to verify the theoretical claims. Index Terms-Isolated DC/DC converter, Dual-Active-Bridge (DAB), Model Predictive Control (MPC)

    COVID-19 and Computer Audition: An Overview on What Speech & Sound Analysis Could Contribute in the SARS-CoV-2 Corona Crisis

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    At the time of writing, the world population is suffering from more than 10,000 registered COVID-19 disease epidemic induced deaths since the outbreak of the Corona virus more than three months ago now officially known as SARS-CoV-2. Since, tremendous efforts have been made worldwide to counter-steer and control the epidemic by now labelled as pandemic. In this contribution, we provide an overview on the potential for computer audition (CA), i.e., the usage of speech and sound analysis by artificial intelligence to help in this scenario. We first survey which types of related or contextually significant phenomena can be automatically assessed from speech or sound. These include the automatic recognition and monitoring of breathing, dry and wet coughing or sneezing sounds, speech under cold, eating behaviour, sleepiness, or pain to name but a few. Then, we consider potential use-cases for exploitation. These include risk assessment and diagnosis based on symptom histograms and their development over time, as well as monitoring of spread, social distancing and its effects, treatment and recovery, and patient wellbeing. We quickly guide further through challenges that need to be faced for real-life usage. We come to the conclusion that CA appears ready for implementation of (pre-)diagnosis and monitoring tools, and more generally provides rich and significant, yet so far untapped potential in the fight against COVID-19 spread

    Photoproduction and Radiative Decay of Spin 1/2 and 3/2 Pentaquarks

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    We study photoproduction and radiative decays of pentauqarks paying particular attention to the differences between spin-1/2 and spin-3/2, positive and negative parities of pentaquarks. Detailed study of these processes can not only give crucial information about the spin, but also the parity of pentaquarks.Comment: 14 pages, 7 figure

    Heavy quarkonium 2S states in light-front quark model

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    We study the charmonium 2S states ψ′\psi' and ηc′\eta_c', and the bottomonium 2S states Υ′\Upsilon' and ηb′\eta_b', using the light-front quark model and the 2S state wave function of harmonic oscillator as the approximation of the 2S quarkonium wave function. The decay constants, transition form factors and masses of these mesons are calculated and compared with experimental data. Predictions of quantities such as Br(ψ′→γηc′)(\psi' \to \gamma \eta_c') are made. The 2S wave function may help us learn more about the structure of these heavy quarkonia.Comment: 5 latex pages, final version for journal publicatio

    Spin-Fluctuation-Induced Non-Fermi-Liquid Behavior with suppressed superconductivity in LiFe1−x_{1-x}Cox_{x}As

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    A series of LiFe1−x_{1-x}Cox_{x}As compounds with different Co concentrations have been studied by transport, optical spectroscopy, angle-resolved photoemission spectroscopy and nuclear magnetic resonance. We observed a Fermi liquid to non-Fermi liquid to Fermi liquid (FL-NFL-FL) crossover alongside a monotonic suppression of the superconductivity with increasing Co content. In parallel to the FL-NFL-FL crossover, we found that both the low-energy spin fluctuations and Fermi surface nesting are enhanced and then diminished, strongly suggesting that the NFL behavior in LiFe1−x_{1-x}Cox_{x}As is induced by low-energy spin fluctuations which are very likely tuned by Fermi surface nesting. Our study reveals a unique phase diagram of LiFe1−x_{1-x}Cox_{x}As where the region of NFL is moved to the boundary of the superconducting phase, implying that they are probably governed by different mechanisms.Comment: 10 pages, 11 figure
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