A Study of the SPWM High-Frequency Harmonic Circulating Currents in Modular Inverters

Xu, Sheng,Ji, Zhendong The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

Due to detection and control errors, some high-frequency harmonics with voltage-source characteristics cause circulating currents in modular inverters. Moreover, the circulating currents are usually affected by the output filters (OF) of each module due to their filter and resonance properties. The interaction among the circulating currents in the modules increase the power loss and reduce system stability and control precision. Therefore, this paper reports the results of a study on the SPWM high-frequency harmonics circulating currents for a double-module VSI. In the paper, an analysis of the circulating-current circuits is briefly described. Next, a mathematic model of the single-module output voltage based on the carrier frequency of SPWM is built. On this basis, through mathematic modeling of high-frequency harmonic circulating currents, the formation mechanism and distribution characteristics of circular currents and their influences are studied in detail. Finally, the influences of the OF on the circulating currents are studied by mainly taking an LC-type filter as an example. A theoretical analysis and experimental results demonstrate some important characteristics. First, the carrier phase shifting of the SPWM for each module is the major cause of the SPWM harmonic circulating currents, and the circulating currents are in an odd distribution around n-times the carrier frequency $n{\omega}_s$, where n = 1, 2, 3, ${\ldots}$. Second, the harmonic circular currents do not flow into the parallel system. Third, the OF can effectively suppress the non-circulating part of the high-frequency harmonic currents but is ineffective for the circulation part, and actually reduces system stability.

Assembly of micro/nanomaterials into complex, three-dimensional architectures by compressive buckling

Xu, Sheng,Yan, Zheng,Jang, Kyung-In,Huang, Wen,Fu, Haoran,Kim, Jeonghyun,Wei, Zijun,Flavin, Matthew,McCracken, Joselle,Wang, Renhan,Badea, Adina,Liu, Yuhao,Xiao, Dongqing,Zhou, Guoyan,Lee, Jungwoo,Chu American Association for the Advancement of Scienc 2015 Science Vol.347 No.6218

<P><B>Popping materials and devices from 2D into 3D</B></P><P>Curved, thin, flexible complex three-dimensional (3D) structures can be very hard to manufacture at small length scales. Xu <I>et al.</I> develop an ingenious design strategy for the microfabrication of complex geometric 3D mesostructures that derive from the out-of-plane buckling of an originally planar structural layout (see the Perspective by Ye and Tsukruk). Finite element analysis of the mechanics makes it possible to design the two 2D patterns, which is then attached to a previously strained substrate at a number of points. Relaxing of the substrate causes the patterned material to bend and buckle, leading to its 3D shape.</P><P><I>Science</I>, this issue p. 154; see also p. 130</P><P>Complex three-dimensional (3D) structures in biology (e.g., cytoskeletal webs, neural circuits, and vasculature networks) form naturally to provide essential functions in even the most basic forms of life. Compelling opportunities exist for analogous 3D architectures in human-made devices, but design options are constrained by existing capabilities in materials growth and assembly. We report routes to previously inaccessible classes of 3D constructs in advanced materials, including device-grade silicon. The schemes involve geometric transformation of 2D micro/nanostructures into extended 3D layouts by compressive buckling. Demonstrations include experimental and theoretical studies of more than 40 representative geometries, from single and multiple helices, toroids, and conical spirals to structures that resemble spherical baskets, cuboid cages, starbursts, flowers, scaffolds, fences, and frameworks, each with single- and/or multiple-level configurations.</P>

Experimental Study of the Salt Transfer in a Cold Sodium Sulfate Soil

Xusheng Wan,Fumao Gong,Mengfei Qu,Enxi Qiu,Changmao Zhong 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.4

Salt migration and accumulation are the main sources of salt expansion. To study the role of salt transport in soil, laboratory tests were conducted to simulate salt transfer under real conditions. Temperature, water content, salt content and soil displacement of a sodium sulfate soil were measured during the freezing process/freeze-thaw cycles. Meanwhile, Salt concentration was regressed bases on test data to investigate the movement of salt diffusion, in the process, the Pitzer ion model was employed to calculate the freezing point of saline soils to determine the frozen depth. Moreover, the amount of crystallization was estimated by the saturation curve of a sodium sulfate solution and the detected salt content. The results show that salt transfer in soil occurs as a result of numerous physicochemical processes and that the maximum salt transport occurred in the frozen fringe zone in the soil. Salt crystallization increases the effect of salt transfer in the soil unidirectional freezing process. In addition, salt expansion had an accumulative effect, and it increases as the number of freeze-thaw cycles increases. The quantity of salt that is transported increases as the salt content increases.

Accuracy Improving Deformation Measurement System for Large Components in Thermal Vacuum Using Close-Range Photogrammetry

Xusheng Zhu,Lei Liu,Xuemei Chen 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.7

The structure deformation of the spacecraft due to the variation of temperature in space has a significant effect on the performance and stability of the spacecraft. Therefore, a system with high accuracy to identify the deformation is proposed in this study for large components in thermal vacuum using close-range photogrammetry. A novel thermal vacuum deformation measurement platform is firstly presented to provide a space simulation chamber in where not only temperature of specimen are available from − 170 to + 140 °C, but also coordinates of measurement points of component can be efficiently measured by using close-photogrammetry. In addition, an improved deformation computation method based on coordinate optimization registration is proposed. In this method, through combining random sample consensus with singular value decomposition, partial global points whose variations are relatively small can be selected for coordinate registration. Finally, the deformation measurement for the main reflector of a Cassegrain antenna in thermal vacuum is selected as an example to validate the effectiveness of the proposed platform and method. The experimental results show that the platform and method are practical and will provide a foundation for further applications.

Effect of serotonin on the cell viability of the bovine mammary alveolar cell-T (MAC-T) cell line

Xusheng Dong,Chen Liu,Jialin Miao,Xueyan Lin,Yun Wang,Zhong-Hua Wang,Qiuling Hou 한국축산학회 2022 한국축산학회지 Vol.64 No.5

5-Hydroxytryptamine (5-HT), a monoamine, as a local regulator in the mammary gland is achemical signal produced by the mammary epithelium cell. In cows, studies have shown that5-HT is associated with epithelial cell apoptosis during the degenerative phase of the mammarygland. However, studies in other tissues have shown that 5-HT can effectively promotecell viability. Whether 5-HT could have an effect on mammary cell viability in dairy cows isstill unknown. The purpose of this study was to determine: (1) effect of 5-HT on the viability ofbovine mammary epithelial cells and its related signaling pathways, (2) interaction betweenprolactin (PRL) and 5-HT on the cell viability. The bovine mammary alveolar cell-T (MAC-T)were cultured with different concentrations of 5-HT for 12, 24, 48 or 72 hours, and then wereassayed using cell counting kit-8, polymerase chain reaction (PCR) and immunobloting. Theresults suggested that 20 μM 5-HT treatment for 12 or 24 h promote cell viability, which wasmainly induced by the activation of 5-HT receptor (5-HTR) 1B and 4, because the increasecaused by 5-HT vanished when 5-HTR 1B and 4 was blocked by SB224289 and SB204070. And protein expression of mammalian target of rapamycin (mTOR), eukaryotic translationelongation factor 2 (eEF2), janus kinase 2 (JAK2) and signal transducer and activator of transcription5 (STAT5) were decreased after blocking 5-HT 1B and 4 receptors. When MAC-Tcells were treated with 5-HT and PRL simultaneously for 24 h, both the cell viability and thelevel of mTOR protein were significantly higher than that cultured with 5-HT or PRL alone. Inconclusion, our study suggested that 5-HT promotes the viability of MAC-T cells by 5-HTR1B and/or 4. Furthermore, there is a reciprocal relationship between PRL and 5-HT.

Characterization of the Hot Deformation Behaviour of an As-Extruded Al–Cu–Li Alloy by Constitutive Analysis

Xusheng Yang,Weijiu Huang,Xianghui Zhu,Ran Zhang,Fei Guo,Li Hu 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

The true stress–strain curves of an as-extruded state AA2099 were determined by uniaxial compression tests under varioushot deformation regimes. Constitutive analysis of the curves allowed calculation of the hot deformation activation energy(QHW). The microstructure of the as-compressed specimens were also characterized by electron back scatter diffraction(EBSD). EBSD data analyses showed that the major restoration mechanism corresponding to common industrial extrusionregimes was dynamic recovery. The precipitates in three states (T83, as-homogenized, and as-extruded) were characterizedby X-ray diffraction (XRD) phase analyses and transmission electron microscopy. The results revealed that the QHWwasclosely relevant to the precipitates strengthening. The finite element method simulation results and the microstructure of theextruded products confirmed that AA2099 in as-extruded state possessed good workability.

Influence of δ' Phase with GP‑I Zones Fillings on Slip Behavior and Cold Rolling Texture in AA2099

Xusheng Yang,Weijiu Huang,Xianghui Zhu,Fei Guo,Yanlong Ma,Linjiang Chai,Ran Zhang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9

The cold rolling texture of AA2099 sheets was strongly influenced by the prior heat treatment. Two typical heat treatments,including solid solution (T4) and underaging (T6) were utilized to control slip behavior by different precipitates during coldrolling. A much weaker texture with an orientation scatter towards higher Φ angles was found in the as-rolled T6 specimen(T6R). Slip behavior was analyzed using geometry necessary boundaries distribution. Results show that the T6R specimenexperienced a strong co-planar slip compared to the as-rolled T4 specimen. Prosperity of co-planar slips and limitation ofco-direction slips were main reasons for the weakening of Copper texture component in the T6R specimen. The distinguishslip behavior was caused by existence of δ' phase with GP-I zones fillings in the T6 specimen. This phase could be easilysheared by dislocations and then promoted co-planar slips in further deformation.

Physics-informed neural networks: A deep learning framework for solving the vibrational problems

Wang, Xusheng,Zhang, Liang Techno-Press 2021 Advances in nano research Vol.11 No.5

The provided paper considers the vibrations of viscoelastic sandwich disk reinforced by graphene nano-platelets (GPLs) filled viscoelastic concrete (GPLRVC) honeycomb core and face sheets via deep learning. The optimum values of the parameters involved in the fully connected neural network are determined through the momentum-based optimizer. The strength of the method applied in this study comes from the high accuracy besides lower epochs needed to train the multi-layered network. The honeycomb core would be manufactured by aluminum according to its great stiffness and lightweight. The mixture rule and modified Halpin-Tsai model have been involved in creating an efficient concrete material constant. By applying energy methods, the system's governing equations have been extracted and solved through Generalize Differential Quadrature (GDQ) technique. In the given research, Kelvin-Voigt viscoelasticity has been applied to model viscoelastic properties. The time-dependent deflection would be solved applying the fourth-order Runge-Kutta computational approach. Then, a parametric study has been conducted to analyze the influences of the external and internal radius ratio, thickness to length ratio of the concrete, hexagonal core angle, the GPLs' weight fraction, and the honeycomb core's thickness to internal radius ratio on the vibrations of the viscoelastic sandwich disk considering face sheet of FG-GPLRVC and honeycomb core.

Microstructures and Mechanical Properties of In-Situ Al3Ti/2024 Aluminum Matrix Composites Fabricated by Ultrasonic Treatment and Subsequent Squeeze Casting

Gang Chen,Xusheng Chang,Jingxuan Zhang,Yu Jin,Cheng Sun,Qiang Chen,Zude Zhao 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.10

Squeeze casting is a near net shaping technology which is advantageous to refining the microstructures and improving themechanical properties. In the present work, in-situ Al3Ti/2024 Aluminum matrix composites with different amount of Al3Tireinforcements were successfully fabricated by ultrasonic treatment and subsequent squeeze casting. The effects of specificpressure and the amount of reinforcements on microstructures and mechanical properties were studied. The results show thatwhen the specific pressure is increased from 0 to 150 MPa, the average grain sizes of α-Al matrix are decreased by 39.8%, andthe yield strength and compressive strength are increased by 16.8% and 22.9%, respectively. However, severe segregationsof eutectic structures were generated under an excessive specific pressure of 200 MPa, which also results in deterioration inthe mechanical strength. The mass fraction of Al3Tiphases has significant influence on morphology of eutectic structures. When the mass fraction of Al3Tiphases is increased from 4 to 16 wt%, the eutectic structures was changed from continuousnetwork to dispersed structures gradually. The compressive strength was increased from 611.2 to 712.0 MPa (increasedby 16.5%), as the Al3Ticontent increasing from 0 to 16 wt%. However, as the mass fraction of Al3Tiphases increased, thevariation in the yield strength is not monotonically increasing.

ICAM-1 shRNA attenuates liver injury after warm ischemia reperfusion

Benjamin Navarro,Xusheng Zhang,Xiufen Zheng,Anthony Jevnikar,Weiping Min,Douglas Quan 한국간담췌외과학회 2013 한국간담췌외과학회 학술대회지 Vol.2013 No.4