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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Multistage Interband Cascade Thermophotovoltaic Devices with ~0.2 eV Bandgap
摘要： Detection of defects in induction machine rotor bars for disassembled motors are required to evaluate machines considered for repair as well as fulfilling incremental quality assurance checks in the manufacture of new machines. Detection of rotor bar defects prior to motor assembly are critical in increasing repair efficiency and assuring the quality of newly manufactured machines. Many methods of detecting rotor bar defects in unassembled motors lack the sensitivity to find both major and minor defects in both cast and fabricated rotors along with additional deficiencies in quantifiable test results and arc-flash safety hazards. A process of direct magnetic field analysis can examine measurements from induced currents in a rotor separated from its stator yielding a high-resolution fingerprint of a rotor’s magnetic field. This process identifies both major and minor rotor bar defects in a repeatable and quantifiable manner appropriate for numerical evaluation without arc-flash safety hazards.
关键词： magnetic flux,ac motors,electromagnetic measurements,induction motors,rotors,AC machines
更新于2025-09-23 15:21:01
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Dipole Switchable Poly(para-phenyleneethynylene)s: Ferroelectric Conjugated Polymers
摘要： Dipolar 2,3-difluorobenzene-units are introduced into the backbone of a poly(para-phenyleneethynylene) (PPE) to generate a ferroelectric conjugated polymer. The structural features of the partially fluorinated PPE allow for the generation of a remanent polarization in the solid state: The difluorinated benzene rings behave as molecular rotors at high temperature, while at room temperature, stacking of such rings clamps down the ring orientation. The molecular dipoles can still be oriented by moderate external electrical fields at room temperature, and this PPE is then a ferroelectric. The concept should be transferable to other poly(aryleneethynylene)s and novel conjugated ferroelectric conjugated polymers will be accessible using this concept.
关键词： Molecular Rotors,Molecular devices,Organic Ferroelectrics,Polymers
更新于2025-09-23 15:21:01
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Dipole Switchable Poly(para-phenyleneethynylene)s: Ferroelectric Conjugated Polymers
摘要： Dipolar 2,3-difluorobenzene-units are introduced into the backbone of a poly(para-phenyleneethynylene) (PPE) to generate a ferroelectric conjugated polymer. The structural features of the partially fluorinated PPE allow for the generation of a remanent polarization in the solid state: The difluorinated benzene rings behave as molecular rotors at high temperature, while at room temperature, stacking of such rings clamps down the ring orientation. The molecular dipoles can still be oriented by moderate external electrical fields at room temperature, and this PPE is then a ferroelectric. The concept should be transferable to other poly(aryleneethynylene)s and novel conjugated ferroelectric conjugated polymers will be accessible using this concept.
关键词： Molecular Rotors,Molecular devices,Organic Ferroelectrics,Polymers
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE International Conference on Space Optical Systems and Applications (ICSOS) - Portland, OR, USA (2019.10.14-2019.10.16)] 2019 IEEE International Conference on Space Optical Systems and Applications (ICSOS) - High Power Indium Phosphide Photonic Integrated Circuit for Pulse Position Modulation Free Space Optical Communications
摘要： Detection of defects in induction machine rotor bars for disassembled motors are required to evaluate machines considered for repair as well as fulfilling incremental quality assurance checks in the manufacture of new machines. Detection of rotor bar defects prior to motor assembly are critical in increasing repair efficiency and assuring the quality of newly manufactured machines. Many methods of detecting rotor bar defects in unassembled motors lack the sensitivity to find both major and minor defects in both cast and fabricated rotors along with additional deficiencies in quantifiable test results and arc-flash safety hazards. A process of direct magnetic field analysis can examine measurements from induced currents in a rotor separated from its stator yielding a high-resolution fingerprint of a rotor’s magnetic field. This process identifies both major and minor rotor bar defects in a repeatable and quantifiable manner appropriate for numerical evaluation without arc-flash safety hazards.
关键词： magnetic flux,ac motors,electromagnetic measurements,induction motors,rotors,AC machines
更新于2025-09-19 17:13:59
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Low-Light Image Enhancement with Semi-Decoupled Decomposition
摘要： Detection of defects in induction machine rotor bars for disassembled motors are required to evaluate machines considered for repair as well as fulfilling incremental quality assurance checks in the manufacture of new machines. Detection of rotor bar defects prior to motor assembly are critical in increasing repair efficiency and assuring the quality of newly manufactured machines. Many methods of detecting rotor bar defects in unassembled motors lack the sensitivity to find both major and minor defects in both cast and fabricated rotors along with additional deficiencies in quantifiable test results and arc-flash safety hazards. A process of direct magnetic field analysis can examine measurements from induced currents in a rotor separated from its stator yielding a high-resolution fingerprint of a rotor’s magnetic field. This process identifies both major and minor rotor bar defects in a repeatable and quantifiable manner appropriate for numerical evaluation without arc-flash safety hazards.
关键词： induction motors,ac motors,electromagnetic measurements,magnetic flux,AC machines,rotors
更新于2025-09-16 10:30:52
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Dynamics of polar polarizable rotors acted upon by unipolar electromagnetic pulses: From the sudden to the adiabatic regime
摘要： We study, analytically as well as numerically, the dynamics that arises from the interaction of a polar polarizable rigid rotor with single unipolar electromagnetic pulses of varying length, ?τ, with respect to the rotational period of the rotor, τr. In the sudden, non-adiabatic limit, ?τ (cid:28) τr, we derive analytic expressions for the rotor’s wavefunctions, kinetic energies, and ?eld-free evolution of orientation and alignment. We verify the analytic results by solving the corresponding time-dependent Schr¨odinger equation numerically and extend the temporal range of the interactions considered all the way to the adiabatic limit, ?τ > τr, where general analytic solutions beyond the ?eld-free case are no longer available. The effects of the orienting and aligning interactions as well as of their combination on the post-pulse populations of the rotational states are visualized as functions of the orienting and aligning kick strengths in terms of population quilts. Quantum carpets that encapsulate the evolution of the rotational wavepackets provide the space-time portraits of the resulting dynamics. The population quilts and quantum carpets reveal that purely orienting, purely aligning, or even-break combined interactions each exhibit sui generis dynamics. In the intermediate temporal regime, we ?nd that the wavepackets as functions of the orienting and aligning kick strengths show resonances that correspond to diminished kinetic energies at particular values of the pulse duration.
关键词： sudden regime,population quilts,adiabatic regime,polar polarizable rotors,unipolar electromagnetic pulses,quantum carpets
更新于2025-09-09 09:28:46
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Echo Spectroscopy in Multilevel Quantum-Mechanical Rotors
摘要： We study the dynamics of rotational echoes in gas phase molecular ensembles and their dependence on the delay and intensity of the excitation pulses. We explore the unique dynamics of alignment echoes that arise from the multilevel nature of the molecular rotors and impose severe difficulties in utilizing echo responses for rotational spectroscopy. We show experimentally and theoretically that judicious control of both the delay and intensity of the second pulse enables multilevel “rotational echo spectroscopy.” The proposed methodology paves the way to rotational spectroscopy in high-density gas samples.
关键词： rotational echoes,echo spectroscopy,gas phase molecular ensembles,multilevel quantum-mechanical rotors
更新于2025-09-04 15:30:14
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Restriction of Molecular Rotors in Ultrathin Two-Dimensional Covalent Organic Framework Nanosheets for Sensing Signal Amplification
摘要： Covalent organic frameworks (COFs) have emerged as promising crystalline porous materials with well-defined structures, high porosity, tunable topology and functionalities suitable for various applications. However, studies of few-layered ultrathin two-dimensional (2D) COF nanosheets, which may lead to unprecedented properties and applications, are still limited. Herein we report the targeted synthesis of three azine-linked and imine-linked 2D COFs named NUS 30-32 using monomers containing aggregation-induced emission (AIE) rotor-active tetraphenylethylene (TPE) moieties, affording micro- and meso- dual pores in NUS-30 and NUS-32, and triple pores in NUS-31. For the first time, we demonstrate that these isostructural bulk COF powders can be exfoliated into ultrathin 2D nanosheets (2 – 4 nm thickness) by temperature-swing gas exfoliation approach. Compared with TPE monomers and COF model compounds, the AIE characteristic of NUS 30-32 nanosheets is distinctly suppressed due to the covalent restriction of the AIE molecular rotors in the confined 2D frameworks. As a result, the enhancement of conjugated conformations of NUS 30-32 nanosheets with unusual structure relaxation show signal amplification effect in biomolecular recognition of amino acids and small pharmaceutical molecules (L-dopa), exhibiting much higher sensitivity than their stacked bulk powders, TPE monomer, and COF model compound. Moreover, the binding affinity of the COF nanosheets toward amino acids can be controlled by increasing the number of azine moieties in the structure. Density functional theory (DFT) calculations reveal that binding affinity control results from the crucial geometric roles and stronger host-guest binding between azine moieties and amino acids. In addition, we demonstrate that minimal loading of the NUS-30 nanosheets in composite membranes can afford excellent performance for biomolecule detection. Our findings pave a way for the development of functional ultrathin 2D COF nanosheets with precise control over the nature, density, and arrangement of the binding active sites involved in enhanced molecule recognition.
关键词： molecular rotors,Covalent organic frameworks,aggregation-induced emission,biomolecular recognition,signal amplification,two-dimensional nanosheets
更新于2025-09-04 15:30:14