Electro-optomechanical equivalent circuits for quantum transduction

Using the techniques of optomechanics, a high-$Q$ mechanical oscillator may serve as a link between electromagnetic modes of vastly different frequencies. This approach has successfully been exploited for the frequency conversion of classical signals and has the potential of performing quantum state transfer between superconducting circuitry and a traveling optical signal. Such transducers are often operated in a linear regime, where the hybrid system can be described using linear response theory based on the Heisenberg-Langevin equations. While mathematically straightforward to solve, this approach yields little intuition about the dynamics of the hybrid system to aid the optimization of the transducer. As an analysis and design tool for such electro-optomechanical transducers, we introduce an equivalent circuit formalism, where the entire transducer is represented by an electrical circuit. Thereby we integrate the transduction functionality of optomechanical systems into the toolbox of electrical engineering allowing the use of its well-established design techniques. This unifying impedance description can be applied both for static (DC) and harmonically varying (AC) drive fields, accommodates arbitrary linear circuits, and is not restricted to the resolved-sideband regime. Furthermore, by establishing the quantized input-output formalism for the equivalent circuit, we obtain the scattering matrix for linear transducers using circuit analysis, and thereby have a complete quantum mechanical characterization of the transducer. Hence, this mapping of the entire transducer to the language of electrical engineering both sheds light on how the transducer performs and can at the same time be used to optimize its performance by aiding the design of a suitable electrical circuit.Comment: 30 pages, 9 figure

First-principles theory of the luminescence lineshape for the triplet transition in diamond NV centre

In this work we present theoretical calculations and analysis of the vibronic structure of the spin-triplet optical transition in diamond nitrogen-vacancy centres. The electronic structure of the defect is described using accurate first-principles methods based on hybrid functionals. We devise a computational methodology to determine the coupling between electrons and phonons during an optical transition in the dilute limit. As a result, our approach yields a smooth spectral function of electron-phonon coupling and includes both quasi-localized and bulk phonons on equal footings. The luminescence lineshape is determined via the generating function approach. We obtain a highly accurate description of the luminescence band, including all key parameters such as the Huang-Rhys factor, the Debye-Waller factor, and the frequency of the dominant phonon mode. More importantly, our work provides insight into the vibrational structure of nitrogen vacancy centres, in particular the role of local modes and vibrational resonances. In particular, we find that the pronounced mode at 65 meV is a vibrational resonance, and we quantify localization properties of this mode. These excellent results for the benchmark diamond nitrogen-vacancy centre provide confidence that the procedure can be applied to other defects, including alternative systems that are being considered for applications in quantum information processing

COMPREHENSIVE THERMAL MODELING OF POWER SPLIT HYBRID POWER-TRAIN AND ELECTRONICS

Hybrid electric vehicle (HEV) uses both internal combustion engine (ICE) with an electric system. The combination of the electric power train with the ICE is intended to achieve both better fuel economies than the conventional vehicles and better performance. Several types of HEV exist with different layouts. Recent HEVs\u27 make use of regenerative braking, which converts the vehicles\u27 kinetic energy into electric energy instead of wasting it as heat as conventional brakes do. A hybrid-electric is more fuel efficient than ICE and has less environmental impact. The new HEV with its new Key Characteristics and Configurations (i.e. Mechanical complexity, Multiple driving modes, Multiple prime movers, ... etc) inflict an interference with the existed thermal management system of the conventional vehicles, which leads to a new thermal management issues that should be addressed to enhance the performance of such systems. There is no complete knowledge in the open literature about the thermal management issues of HEV yet. This dissertation introduces Comprehensive Thermal Modeling of Hybrid Vehicular systems to assist monitoring the added-on of hybrid modules into the vehicle thermal management system. The model proposes a combined experimental and finite differencing nodal net work simulation modeling approach; using Thermography detectors calibrated for emissivity to capture 2-D spatial and transient temperature measurements. The Thermographic detectors were deployed through dual band thermography to neutralize the emissivity and to provide different dynamic ranges to iii achieve accurate temperature measurements. A thermocouples network was installed to provide a reference signal. A new comprehensive 3-D thermal model was developed by generating 3-D surface description for a complete hybrid electric vehicle from 3-D scans of an actual vehicle to guarantee the quality of the surface geometry, and break down the surfaces of the model into finite elements to improve the accuracy for better thermal analysis. The boundary conditions from a vehicle under different driving modes and load scenarios were deployed into the finite differencing simulation which was performed using finite differencing code capable of solving a sophisticated thermal/fluid systems with minimal user interaction (RadTherm) to provide a 3-D Thermal predictions and an Image Viewer (wireframe and animated thermal display). The 3-D model assisted monitoring the adding of Hybrid modules into the vehicle thermal management system and was used to analyze packaging considerations and integrating different modules for Hybrid Vehicles. In addition to the design of alternative materials for hybrid modules and Battery Packs for better thermal management; the model assisted studying the influence of applying different cooling methodologies and evaluate its effect on the thermal performance of the HEVs\u27 power trains. A spatial and a transient temperature profiles obtained from the simulation for different components were compared with experimental results in order to validate the complete thermal model

Subject Classification of Collection-level Descriptions Using DDC for Information Landscaping

Collection-level description (CLD) has emerged as an important tool for facilitating user access to large heterogeneous collections within digital library and hybrid information environments. Such metadata enables "information landscaping" techniques to be deployed, thereby allowing users to survey, discover and identify relevant collections. This can aid the precision of item-level queries by eliminating collections which may produce a significant number of false-drops or may contain no relevant items. The ability to provide suitable subject indexing and subject-based organization within such collection-level environments is an increasingly important user requirement, particularly for landscaping; yet it remains highly problematic owing to, for example, the broad subject coverage of many collections and the item-level nature of controlled vocabularies. In this paper we propose a methodology for the subject designation of collections using the Dewey Decimal Classification (DDC). The proposed approach allows the establishment of reliable, consistent and meaningful DDC class numbers to facilitate improved user browsing and searching tools within CLD systems. The methodology will be demonstrated using the Scottish Collections Network (SCONE) and alternative techniques to facilitate general subject analysis will also discussed

The GMAO Hybrid Ensemble-Variational Atmospheric Data Assimilation System: Version 2.0

This document describes the implementation and usage of the Goddard Earth Observing System (GEOS) Hybrid Ensemble-Variational Atmospheric Data Assimilation System (Hybrid EVADAS). Its aim is to provide comprehensive guidance to users of GEOS ADAS interested in experimenting with its hybrid functionalities. The document is also aimed at providing a short summary of the state-of-science in this release of the hybrid system. As explained here, the ensemble data assimilation system (EnADAS) mechanism added to GEOS ADAS to enable hybrid data assimilation applications has been introduced to the pre-existing machinery of GEOS in the most non-intrusive possible way. Only very minor changes have been made to the original scripts controlling GEOS ADAS with the objective of facilitating its usage by both researchers and the GMAO's near-real-time Forward Processing applications. In a hybrid scenario two data assimilation systems run concurrently in a two-way feedback mode such that: the ensemble provides background ensemble perturbations required by the ADAS deterministic (typically high resolution) hybrid analysis; and the deterministic ADAS provides analysis information for recentering of the EnADAS analyses and information necessary to ensure that observation bias correction procedures are consistent between both the deterministic ADAS and the EnADAS. The nonintrusive approach to introducing hybrid capability to GEOS ADAS means, in particular, that previously existing features continue to be available. Thus, not only is this upgraded version of GEOS ADAS capable of supporting new applications such as Hybrid 3D-Var, 3D-EnVar, 4D-EnVar and Hybrid 4D-EnVar, it remains possible to use GEOS ADAS in its traditional 3D-Var mode which has been used in both MERRA and MERRA-2. Furthermore, as described in this document, GEOS ADAS also supports a configuration for exercising a purely ensemble-based assimilation strategy which can be fully decoupled from its variational component. We should point out that Release 1.0 of this document was made available to GMAO in mid-2013, when we introduced Hybrid 3D-Var capability to GEOS ADAS. This initial version of the documentation included a considerably different state-of-science introductory section but many of the same detailed description of the mechanisms of GEOS EnADAS. We are glad to report that a few of the desirable Future Works listed in Release 1.0 have now been added to the present version of GEOS EnADAS. These include the ability to exercise an Ensemble Prediction System that uses the ensemble analyses of GEOS EnADAS and (a very early, but functional version of) a tool to support Ensemble Forecast Sensitivity and Observation Impact applications

Obtaining Preferences from a Hybrid Learning System to Promote English-Speaking Ability through Focus Group Discussion

In the new normal era, the learning system has changed from online learning to hybrid learning. This learning system is widely applied in many universities. Thus surfacing students and lecturers’ voices is of absolute importance in obtaining preferences for best practices in English language teaching. In the EFL context, speaking fluency is one of the elements of speaking that have many difficulties to be mastered by students. This study was conducted to derive suggestions and preferences for best practices in hybrid learning systems for English-speaking ability through Focus Group Discussion (FGD) method. From the FGD, we draw transcripts, back-to-back translations, field notes and activity artefacts to demonstrate the process of the discussion. The information gathered was examined using thematic analysis and an interpretative description approach. The participants of this study were Non-English majors and English lecturers. The result revealed that college students faced speaking challenges during hybrid learning to hone their speaking fluency. Emerging themes were identified wherein in a hybrid learning system, the lecturer utilized multifaceted learning, digital resources and communication tools to improve students' speaking fluency. As for the implementation, technical support and mental readiness for hybrid learning are the reasons for the possibility of hybrid learning that affects students' speaking fluency