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  • AIP Publishing  (20)
  • 1
    Online Resource
    Online Resource
    Numerical investigations on the mechanisms of the tip leakage vortex cavitation development in a cryogenic inducer with large eddy simulation
    AIP Publishing ; 2023
    In:  Physics of Fluids Vol. 35, No. 7 ( 2023-07-01)
    Details
    In: Physics of Fluids, AIP Publishing, Vol. 35, No. 7 ( 2023-07-01)
    Abstract: Liquid hydrogen is considered clean energy and is usually pressurized by cryogenic pumps in various industries. To ensure the safe operation of cryogenic pumps, the inducer is installed in front of the pump to improve the impeller inlet pressure but causes cavitation instabilities. This paper aims to investigate the mechanisms of the tip leakage vortex (TLV) cavitating flow in a cryogenic inducer with liquid nitrogen. The large eddy simulations model was used to analyze the thermodynamic effects on the tip leakage vortex cavitation (TLVC). The cavity structure and the pulsation mechanisms of the TLVC were analyzed through the flow characteristics and the vorticity transportation process. The predicted cavitation performance is in good agreement with the experimental measurements. The numerical results showed that the TLVC is suppressed and forms the separation point between the primary TLVC and the secondary TLVC due to the thermodynamic effects. The inhibition rate of the vapor volume fraction at the leading edge is 30%. The pressure fluctuations are caused by the propagation pattern of the detached cavity interacting with the adjacent blade periodically. The velocity triangles near the detached cavity were proposed to reveal the development of the TLVC. It indicates that TLVC instability is caused by the periodic coupling effect of the cavity development, the flow rate magnitude, and the local incidence angle variation. The vorticity transport equation is utilized to investigate the interaction of cavitation and vortex. Comparing the three terms reveals that the stretching and bending term dominates in the vorticity production of the TLV cavitating flow. The dilatation term controls the transportation of vorticity inside the TLV cavity, while the contribution of the baroclinic torque term is negligible in comparison to the other terms. This study provides a reference for optimizing the TLV cavitating flow and instabilities for designing the cryogenic pump.
    Type of Medium: Online Resource
    ISSN: 1070-6631 , 1089-7666
    URL: Article
    DOI: 10.1063/5.0154932
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1472743-2
    detail.hit.zdb_id: 241528-8
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  • 2
    Online Resource
    Online Resource
    Multi-domain substructures synthesis with general joints for the dynamics of large structures
    AIP Publishing ; 2017
    In:  AIP Advances Vol. 7, No. 10 ( 2017-10-01)
    Details
    In: AIP Advances, AIP Publishing, Vol. 7, No. 10 ( 2017-10-01)
    Abstract: In this paper, a method for the assembly of multi-domain substructures with general joints is proposed. Modal domain and physical domain substructures can be coupled in a unified framework. Specially, the physical domain substructures are represented using the impulse response functions of substructures. The modal domain substructures are generated using the Craig–Bampton method. With the introduction of general joints, complex connections like hybrid rigid-elastic or nonlinear connections are able to be considered. Meanwhile, only degree of freedoms directly associated with the joints are retained for the synthesis that makes this method quite suitable for local nonlinear structures. The validity of the proposed method is demonstrated by numerical examples. And the application to the dynamics of a practical lunar lander is provided. The results show that the proposed method possesses high precision and is quite efficient with the reduced substructures employed and a few joints degree of freedoms involved.
    Type of Medium: Online Resource
    ISSN: 2158-3226
    URL: Article
    DOI: 10.1063/1.4999110
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2017
    detail.hit.zdb_id: 2583909-3
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  • 3
    Online Resource
    Online Resource
    RF performance enhancement in sub- μ m scaled β-Ga2O3 tri-gate FinFETs
    AIP Publishing ; 2022
    In:  Applied Physics Letters Vol. 121, No. 7 ( 2022-08-15)
    Details
    In: Applied Physics Letters, AIP Publishing, Vol. 121, No. 7 ( 2022-08-15)
    Abstract: In this Letter, we report on the enhanced radio frequency (RF) performance in sub-micrometer scaled β-Ga2O3 tri-gate FinFETs. With a 200-nm-thick β-Ga2O3 bulk channel and a 0.35 μm gate length, the FinFETs exhibit an improved current-gain cutoff frequency of 5.4 GHz and a maximum oscillation frequency of 11.4 GHz, which are 20% and 58% improved with respect to the planar counterpart, respectively. The improved RF performance results from the enhanced gate control capability and the suppressed short-channel effects, as evidenced by the improved pinch-off characteristics, the improved transconductance, and the suppressed output conductance. It suggests that the tri-gate multi-fin architecture is a promising strategy to break the scaling limitation of the gate-channel aspect ratio toward high-performance β-Ga2O3 RF MOSFETs.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    URL: Article
    DOI: 10.1063/5.0098610
    RVK:
    UA 1000
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
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  • 4
    Online Resource
    Online Resource
    A comparative study of principal component analysis and independent component analysis in eddy current pulsed thermography data processing
    AIP Publishing ; 2013
    In:  Review of Scientific Instruments Vol. 84, No. 10 ( 2013-10-01)
    Details
    In: Review of Scientific Instruments, AIP Publishing, Vol. 84, No. 10 ( 2013-10-01)
    Abstract: Eddy Current Pulsed Thermography (ECPT), an emerging Non-Destructive Testing and Evaluation technique, has been applied for a wide range of materials. The lateral heat diffusion leads to decreasing of temperature contrast between defect and defect-free area. To enhance the flaw contrast, different statistical methods, such as Principal Component Analysis and Independent Component Analysis, have been proposed for thermography image sequences processing in recent years. However, there is lack of direct and detailed independent comparisons in both algorithm implementations. The aim of this article is to compare the two methods and to determine the optimized technique for flaw contrast enhancement in ECPT data. Verification experiments are conducted on artificial and thermal fatigue nature crack detection.
    Type of Medium: Online Resource
    ISSN: 0034-6748 , 1089-7623
    URL: Article
    DOI: 10.1063/1.4823521
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2013
    detail.hit.zdb_id: 209865-9
    detail.hit.zdb_id: 1472905-2
    SSG: 11
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  • 5
    Online Resource
    Online Resource
    A micromechanics model to predict effective thermal conductivity of rGO/MMT/polymer composites
    AIP Publishing ; 2021
    In:  Journal of Applied Physics Vol. 129, No. 15 ( 2021-04-21)
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 129, No. 15 ( 2021-04-21)
    Abstract: In recent years, enhanced thermal conductive properties of polymer composites filled with reduced graphene oxide (rGO) have been studied for diverse applications. However, rGO fillers tend to form aggregates, making it difficult to reach the maximum enhancement through the use of rGO. Experiments have shown that the hydrogen bond between rGO and montmorillonite (MMT) can lead to a stable dispersion of rGO with the result of improving the effective thermal conductivity (ETC) of the composite. However, the mechanisms of this phenomenon are not yet well known. In this work, a micromechanics-based method is proposed to provide an analytical expression of the ETC of rGO/MMT/polymer composites. The predictions are in good agreement with the experimental data, demonstrating the effectiveness of the proposed framework. Also, the effect of the orientation of the fillers is investigated, which useful to determine the optimal orientation and filling ratio to meet various requirements in the material performance design and preparation of rGO/MMT/polymer composites.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/5.0030134
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
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  • 6
    Online Resource
    Online Resource
    Frequency feature based quantification of defect depth and thickness
    AIP Publishing ; 2014
    In:  Review of Scientific Instruments Vol. 85, No. 6 ( 2014-06-01)
    Details
    In: Review of Scientific Instruments, AIP Publishing, Vol. 85, No. 6 ( 2014-06-01)
    Abstract: This study develops a frequency feature based pulsed eddy current method. A frequency feature, termed frequency to zero, is proposed for subsurface defects and metal loss quantification in metallic specimens. A curve fitting method is also employed to generate extra frequency components and improve the accuracy of the proposed method. Experimental validation is carried out. Conclusions and further work are derived on the basis of the studies.
    Type of Medium: Online Resource
    ISSN: 0034-6748 , 1089-7623
    URL: Article
    DOI: 10.1063/1.4884518
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2014
    detail.hit.zdb_id: 209865-9
    detail.hit.zdb_id: 1472905-2
    SSG: 11
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  • 7
    Online Resource
    Online Resource
    Crystallographic studies of the intergranular phases in sintered PrNd23Ce7Gd1.5FebalB0.93Cu0.35M1 magnet with commercial N40M magnetic properties
    AIP Publishing ; 2023
    In:  AIP Advances Vol. 13, No. 5 ( 2023-05-01)
    Details
    In: AIP Advances, AIP Publishing, Vol. 13, No. 5 ( 2023-05-01)
    Abstract: In this work, we focus on the modification of the Cu element in commercial N40M magnets toward the composition and structure of the grain boundary phase. The magnetic properties and microstructure of Ce-magnets with low and high Cu content were investigated. The Ce-magnet with high Cu-content has higher coercivity and a more continuous and homogenous grain boundary phase. The grain boundary phase’s structural shift is found to be the source of the coercivity change. The transmission electron microscopy study shows that the PrNd23Ce7Gd1.5FebalB0.93Cu0.35M1 magnet contains fcc and hcp type (Ce, Nd)-oxide phases, each with a different O concentration. The formation of the superlattice has been examined, and the superlattice spots show that the Cu-rich phases have an ordered structure.
    Type of Medium: Online Resource
    ISSN: 2158-3226
    URL: Article
    DOI: 10.1063/5.0137911
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 2583909-3
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  • 8
    Online Resource
    Online Resource
    Two-dimensional electron gas related emissions in ZnMgO/ZnO heterostructures
    AIP Publishing ; 2011
    In:  Applied Physics Letters Vol. 99, No. 21 ( 2011-11-21)
    Details
    In: Applied Physics Letters, AIP Publishing, Vol. 99, No. 21 ( 2011-11-21)
    Abstract: Radiative recombination of two-dimensional electron gas (2DEG), induced by polarization and validated by Hall effect measurements, is investigated in ZnMgO/ZnO heterostructures grown by metal-organic chemical vapor deposition. The Mg composition, the depth profile distribution of Mg, the residual strain in ZnMgO caplayer, and the thickness of caplayer all significantly influence the 2DEG-related transitions in ZnMgO/ZnO heterostructures. Below or above ZnO donor bound exciton, three additional broad emissions persisting up to 100 K are assigned to the spatially indirect transitions from 2DEG electrons to the photoexcited holes towards the ZnO flat-band region or remaining at the heterointerface.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    URL: Article
    DOI: 10.1063/1.3662964
    RVK:
    UA 1000
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2011
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
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  • 9
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    Single-crystalline polyhedral In2O3 vertical Fabry–Pérot resonators
    AIP Publishing ; 2011
    In:  Applied Physics Letters Vol. 98, No. 1 ( 2011-01-03)
    Details
    In: Applied Physics Letters, AIP Publishing, Vol. 98, No. 1 ( 2011-01-03)
    Abstract: High-quality In2O3 polyhedrons with different morphologies were fabricated and studied as vertical Fabry–Pérot (FP) microcavities. By using the microphotoluminescence technique, we identified a series of FP resonant modes in such systems, whose energies lie in the visible spectral range and are scalable with the cavity size. Experimental results are in good agreement with full-wave numerical simulations and can be well fitted with a plane wave interference model. Compared with the conventional one dimensional nanowire/nanobelt FP cavities, such vertical FP microcavities have much less optical loss and provide efficient optical modulations, which may find many applications in developing optical devices.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    URL: Article
    DOI: 10.1063/1.3540650
    RVK:
    UA 1000
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2011
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
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  • 10
    Online Resource
    Online Resource
    Asymptotics of the largest eigenvalue distribution of the Laguerre unitary ensemble
    AIP Publishing ; 2021
    In:  Journal of Mathematical Physics Vol. 62, No. 6 ( 2021-06-01)
    Details
    In: Journal of Mathematical Physics, AIP Publishing, Vol. 62, No. 6 ( 2021-06-01)
    Abstract: We study the probability that all the eigenvalues of n × n Hermitian matrices, from the Laguerre unitary ensemble with the weight xγe−4nx,x∈0,∞,γ & gt;−1, lie in the interval [0, α]. By using previous results for finite n obtained by the ladder operator approach of orthogonal polynomials, we derive the large n asymptotics of the largest eigenvalue distribution function with α ranging from 0 to the soft edge. In addition, at the soft edge, we compute the constant conjectured by Tracy and Widom [Commun. Math. Phys. 159, 151–174 (1994)] and later proved by Deift, Its, and Krasovsky [Commun. Math. Phys. 278, 643–678 (2008)]. Our conclusions are reduced to those of Deift et al. when γ = 0. It should be pointed out that our derivation is straightforward but not rigorous, and hence, the above results are stated as conjectures.
    Type of Medium: Online Resource
    ISSN: 0022-2488 , 1089-7658
    URL: Article
    DOI: 10.1063/5.0010029
    RVK:
    UA 4660
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 1472481-9
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