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1

Effects of cooling methods and key parameters on the cooling performance of oil-cooling motor with hairpin windings

Liu Y.U., Wu H., Zhang J., Xu P.X., Cheng S., He X.H., Sun Z.D.

Archives of Thermodynamics

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2024

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Vol. 45, no 2

301--309

EN

Based on the electromagnetic thermal coupling analysis method, the cooling performance of different motor cooling models and the influence of key parameters of the cooling system on the cooling effect of the motor are investigated. First, the losses of various parts of the permanent magnet synchronous motors are obtained through electromagnetic calculations; the analysis results show that the stator core loss, winding copper loss, and eddy current loss of permanent magnets exceed 95% of the total loss of the motor. Second, the cooling performance of the three motor was compared and analyzed. The axial housing liquid cooling and oil spray cooling (Model B) has a better cooling performance and a higher cooling efficiency. Compared with the other two motor models, Model B can reduce the time to reach steady-state temperature by about 81.8%.Then the effects of coolant volume flow rate, coolant inlet temperature, and ambient temperature on the cooling effect of the motor are investigated. The results show that within a certain range, the rate of coolant inlet temperature change is approximately proportional to the internal temperature rise of the motor. The oil spray cooling system of Model B is less affected by ambient temperature and can be used for motor cooling in complex environments. The results of this study can provide a useful guidance for the design of the cooling system and the selection of coolant volume flow rate for oil-cooling motor with hairpin windings.

2

Analysis on electromechanical coupling vibration characteristics of in-wheel motor in electric vehicles considering air gap eccentricity

Li Y., Wu H., Xu X., Cai Y., Sun X.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2019

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Vol. 67, nr 5

851--862

EN

The distortion of air gap magnetic field caused by the rotor eccentricity contributes to the electromechanical coupling vibration of the brushless DC (BLDC) permanent magnet in-wheel motor (PMIWM) in electric vehicles (EV). The comfort of the BLDC in-wheel motor drive (IWMD) EV is seriously affected. To deeply investigate the electromechanical coupling vibration of the PMIWM under air gap eccentricity, the PMIWM, tyre and road excitation are analyzed first. The influence of air gap eccentricity on air gap magnetic density is investigated. The coupling law of the air gap and the unbalanced magnetic force (UMF) is studied. The coupling characteristics of eccentricity rate, air gap magnetic density, UMF, phase current and vibration acceleration are verified on the test bench in the laboratory. The mechanism of the electro-mechanical coupling vibration of the BLDC PMIWM under air gap static eccentricity (SE), dynamic eccentricity (DE) and hybrid eccentricity (HE) is revealed. DE and HE deteriorate the vibration acceleration amplitude, which contributes the electromechanical coupling vibration of the PMIWM. The research results provide a solid foundation for the vibration and noise suppression of the PMIWM in distributed drive EV.

3

Three-dimensional discrete element method simulation of core disking

Wu S., Wu H., Kemeny J.

Acta Geophysica

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2018

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Vol. 66, no. 3

267--282

EN

The phenomenon of core disking is commonly seen in deep drilling of highly stressed regions in the Earth’s crust. Given its close relationship with the in situ stress state, the presence and features of core disking can be used to interpret the stresses when traditional in situ stress measuring techniques are not available. The core disking process was simulated in this paper using the three-dimensional discrete element method software PFC3D (particle flow code). In particular, PFC3D is used to examine the evolution of fracture initiation, propagation and coalescence associated with core disking under various stress states. In this paper, four unresolved problems concerning core disking are investigated with a series of numerical simulations. These simulations also provide some verification of existing results by other researchers: (1) Core disking occurs when the maximum principal stress is about 6.5 times the tensile strength. (2) For most stress situations, core disking occurs from the outer surface, except for the thrust faulting stress regime, where the fractures were found to initiate from the inner part. (3) The anisotropy of the two horizontal principal stresses has an effect on the core disking morphology. (4) The thickness of core disk has a positive relationship with radial stress and a negative relationship with axial stresses.

4

Double-layer microwave absorber based on nanocrystalline CoFe2O4 and CoFe2O4/PANI multi-core/shell composites

Xu Y., Shen G., Wu H., Liu B., Fang X., Zhang D., Zhu J.

Materials Science Poland

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2017

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Vol. 35, No. 1

94--104

EN

Organic-inorganic nano-CoFe2O4/PANI (polyaniline) multi-core/shell composites have been successfully synthesized by chemical oxidative polymerization of aniline. The characterization results showed that the ferrite nanocrystals were efficiently embedded in PANI. The electromagnetic parameters of the composites were measured by a vector network analyser in the frequency range of 2 GHz to 18 GHz. Double-layer absorbers based on the CoFe2O4/PANI composite (matching layer) and calcined CoFe2O4 ferrite (absorbing layer) have been designed. The reflection loss of the microwave absorbers of both single layer and double-layer with a total thickness of 2.0 mm and 2.5 mm was calculated according to transmission-line theory. The results indicated that the minimum reflection loss of the CoFe2O4/PANI composite was −19.0 dB at 16.2 GHz at the thickness of 2.0 mm and −23.6 dB at 13.1 GHz at the thickness of 2.5 mm, respectively. The minimum reflection loss for double-layer absorbers reached −28.8 dB at 16.2 GHz at the total thickness of 2.0 mm, and −31.1 dB at 12.8 GHz at the total thickness of 2.5 mm. The absorption bandwidth under −10 dB was 4.2 GHz (13.8 GHz to 18.0 GHz) and 5.5 GHz (10.3 GHz to 15.8 GHz), respectively. The results show that the reflection loss and absorption bandwidth of the double-layer absorbers are obviously enhanced compared to corresponding single layer absorbers.

5

A polarization selective beam splitter based on a subwavelength multisubpart profile grating structure

Xiao Y., Huang L., Wu H., Sun X., Xiao W., Duan J.

Optica Applicata

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2016

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Vol. 46, nr 4

665--672

EN

In this study, a polarization selective beam splitter constructed by only a single layer subwavelength multisubpart profile grating is presented. Rigorous coupled-wave analysis is adopted to investigate the properties of the structure. It is shown that for a transverse electric polarized wave, the device demonstrates very high reflectivity (>97%) from 1.46 to 1.58 μm; and for a transverse magnetic polarized wave, at the wavelength of 1.55 μm, it exhibits about 50/50 beam ratio under normal incidence. To evaluate the response of the polarizing beam splitters under variation in structure parameters, we also investigated the fabrication tolerances of the device.

6

Bivariate Hahn moments for image reconstruction

Wu H., Yan S.

International Journal of Applied Mathematics and Computer Science

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2014

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Vol. 24, no. 2

417--428

EN

This paper presents a new set of bivariate discrete orthogonal moments which are based on bivariate Hahn polynomials with non-separable basis. The polynomials are scaled to ensure numerical stability. Their computational aspects are discussed in detail. The principle of parameter selection is established by analyzing several plots of polynomials with different kinds of parameters. Appropriate parameters of binary images and a grayscale image are obtained through experimental results. The performance of the proposed moments in describing images is investigated through several image reconstruction experiments, including noisy and noise-free conditions. Comparisons with existing discrete orthogonal moments are also presented. The experimental results show that the proposed moments outperform slightly separable Hahn moments for higher orders.

7

Usefulness of nonlinear interpolation and particle filter in Zigbee indoor positioning

Zhang X., Guo H., Wu H., Uradziński M.

Geodesy and Cartography

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2014

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Vol. 63, no. 2

219--233

EN

The key to fingerprint positioning algorithm is establishing effective fingerprint information database based on different reference nodes of received signal strength indicator (RSSI). Traditional method is to set the location area calibration multiple information sampling points, and collection of a large number sample data what is very time consuming. With Zigbee sensor networks as platform, considering the influence of positioning signal interference, we proposed an improved algorithm of getting virtual database based on polynomial interpolation, while the pre-estimated result was disposed by particle filter. Experimental result shows that this method can generate a quick, simple fine-grained localization information database, and improve the positioning accuracy at the same time.

PL

Kluczem do algorytmu pozycjonowania wykorzystującego metodę fingerprinting jest ustanowienie skutecznej bazy danych na podstawie informacji z radiowych nadajników referencyjnych przy wykorzystaniu wskaźnika mocy odbieranego sygnału (RSSI). Tradycyjna metoda oparta jest na przeprowadzeniu kalibracji obszaru lokalizacji na podstawie wielu punktów pomiarowych i otrzymaniu dużej liczby próbek, co jest bardzo czasochłonne.

8

Quantitative Analysis of Lattice-valued Kripke Structures

Pan H., Zhang M., Wu H., Chen Y

Fundamenta Informaticae

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2014

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Vol. 135, nr 3

269--293

EN

To model and analyze systems with multi-valued information, in this paper, we present an extension of Kripke structures in the framework of complete residuted lattices, which we will refer to as lattice-valued Kripke structures (LKSs). We then show how the traditional trace containment and equivalence relations, can be lifted to the lattice-valued setting, and we introduce two families of lattice-valued versions of the relations. Further, we explore some interesting properties of these relations. Finally, we provide logical characterizations of our relations by a natural extension of linear temporal logic.

9

Distribution Optimization Based on Feasible Direction Metod for Horizontal Well Perforation

Wang Y., Wu X., Wang R., Wu H., Yang Z.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

239--242

EN

The horizontal wellbore pressure and reservoir heterogeneity are major factors in the horizontal well uneven inflow. Given the situation, it is to establish balanced production of horizontal wells as the objective function, and holes dense as the optimization which is a typical constrained nonlinear optimization. By feasible direction method, it is to obtain distribution optimization results, in order to control the production pressure within horizontal section and to realize uniform advancing of flow profile in the horizontal segment.

PL

W artykule przedstawiono metodę optymalizacji rozmieszczenia i gęstości odwiertów oraz zbalansowania ilości studzien poziomych, co zapobiegnie nierównomiernym rozpływom cieczy. Dodatkowo pozwoli to na kontrolę ciśnienia przy wytwarzaniu poziomych sekcji oraz jednorodne przedłużanie profilu przepływu w poziomym segmencie.

10

An all-fibre multi-parameter sensor for composite structures based on a chirped fibre Bragg grating

Zhan Y., Yang F., Gu K., Wu H., Yu M., Li L.

Opto-Electronics Review

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2013

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Vol. 21, No. 3

283-287

EN

An all-fibre multi-parameter sensor for composite structures based on a chirped optical fibre Bragg grating (CFBG) has been studied theoretically and experimentally. The principle of multi-parameters sensing with a single CFBG is based on that the centre wavelength and the FWHM (full width at half maximum) in the reflection spectrum of a CFBG vary linearly with the temperature and/or the axial stress. A wavelength matched optical fibre long period grating (LPG) and another wavelength matched reference CFBG (CFBGR) have been used to interrogate the signal of the sensor CFBG (CFBGS). The temperature and strain of the composite structure have been monitored real-time with one CFBG as a single sensor head. The temperature resolution of 0.12ºC and the strain resolution of 1.1με for a composite structure have been realized in experiments. The experiment results agree well with the theoretical analyses.

11

Phase features of several typical blood cells and their identification without unwrapping

Wang Y., Chen Y, Lü C., Shang X., Xu Y., Wu H., Zhu X., Jin W.

Optica Applicata

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2013

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Vol. 43, nr 3

505--514

EN

The digital holographic phase microscopy (DHPM) technique which has been proposed for cellular morphology and dynamic analysis yielded highly desirable results. However, for nucleated cells (especially white blood cells (WBCs)), their submicroscopic structure has not yet been deconstructed through a phase unwrapping method due to the heterogeneity of an internal phase. By analyzing the phase heterogeneity of subclasses of WBCs, the typical phase models of them are built first in this paper; using the simulation method, the wrapped phase distributions of these models are obtained. However, by optimizing the wrapped phase maps and analyzing the relationships between them and typical blood cells, their features are selected and extracted. Then the models built are sorted out from each other successfully without unwrapping via analyzing these extracted features, which provides a valuable approach and technological base for the classification and identification of blood cells.

12

Novel Design of Inland Shipping Management Information System Based on WSN and Internet-of-things

Wu H., Chen X., Hu Q, Shi C., Mo J.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2012

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Vol. 6, no. 3

307--313

EN

Currently there are more and more ships sailing in inland waterways so that the traditional inland shipping management information system (ISMIS) becomes relatively backward. Based on the rapidly developed new information technologies, such as wireless sensor network, Internet-of-things, cloud-computing and so on, we propose a novel design of ISMIS, which is featured by low cost, environment-friendly, cross platform, high scalability and integrity and thus can efficiently improve the inland shipping management and inland water environment.

13

Study on power efficiency of vortex beam propagation through an optical system with phase optimization

Wu H., Sheng S., Huang Z., Wang H., Zhao S., Xu X., Sun Z., Xiao R.

Optica Applicata

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2012

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Vol. 42, nr 3

597-611

EN

Beam blocked and truncated by the receiver causes serious power losses in beam uplink propagation in a relay mirror system. We propose a method to improve power efficiency of beam uplink propagation in the relay mirror system by using vortex source and phase optimization. A typical model of beam uplink propagation in the relay mirror system is established. With this model, the principle of the method is theoretically analyzed, and power efficiencies of beam uplink propagation under different conditions are calculated. The calculation results show that power efficiency of beam uplink propagation can be improved from 86.44% to 97.86% by using vortex source and phase optimization. A reduced-scale experiment of beam uplink propagation in the relay mirror system under the "closed-loop" mode is performed, and the experimental results show that power efficiency can be improved from 71.89% to 91.59% by using the vortex source and phase optimization.

14

Performance analysis of bit error rate for free space optical communication with tip-tilt compensation based on gamma-gamma distribution

Wu H., Yan H., Li X.

Optica Applicata

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2009

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Vol. 39, nr 3

533-545

EN

In this paper, the gamma - gamma probability distribution is used to model turbulent channels. The bit error rate (BER) performance of free space optical (FSO) communication systems employing on-off keying (OOK) or subcarrier binary phase-shift keying (BPSK) modulation format is derived. A tip-tilt adaptive optics system is also incorporated with a FSO system using the above modulation formats. The tip-tilt compensation can alleviate effects of atmospheric turbulence and thereby improve the BER performance. The improvement is different for different turbulence strengths and modulation formats. In addition, the BER performance of communication systems employing subcarrier BPSK modulation is much better than that of compatible systems employing OOK modulation with or without tip-tilt compensation.

15

Lithium Manganate Grown from Water-Solubility Explosive with EPS

Xie X., Wu H., Wang W., Wang M., Huang W., Li X.

Central European Journal of Energetic Materials

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2006

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Vol. 3, nr 3

15-25

EN

Nanostructured spherical spinel lithium manganate with about 30 nm in diameter was synthesized for the first time by explosive method. The water-solubility explosive was prepared using a simple facility at room temperature. The growth of lithium manganate via detonation reaction was investigated with respect to the presence of an energetic precursor, such as the metallic nitrate and the degree of confinement of the explosive charge. The detonation products were characterized by scanning electron microscopy. Powder X-ray diffraction and transmission electron microscopy were used to characterize the products. Lithium manganate with spherical morphology and more uniform secondary particles, with smaller primary particles of diameters from 10 to 50 nm and a variety of morphologies were found. Lithium manganate with a fine spherical morphology different from that of the normal spinel is formed after detonation wave treatment due to the very high quenching rate. It might also provide a cheap large-scale synthesis method. Explosive detonation is strongly nonequilibrium processes, generating a short duration of high pressure and high temperature. Free metal atoms are first released with the decomposition of explosives, and then theses metal and oxygen atoms are rearranged, coagulated and finally crystallized into lithium manganate during the expansion of detonation process.

16

An approximation method for simulating temperature dependence of Poissonąs ratios of self - expanding auxegens

Wu H., Wei G.

Computational Methods in Science and Technology

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2004

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Vol. 10, nr 2

229-234

EN

A combined molecular dynamics and molecular mechanics method has been developed for estimating Poisson's ratios of certain types of molecular auxetics at various temperatures. The temperature dependence of the auxeticity of a special class of molecular auxetics, namely, a self-expanding supramolecular network of auxegens containing alternating phenyl and acetylene links, is studied with use of this approximation method. The simulation results show that as temperature increases from O to 300 K, the auxeticity of the resulting superlattice or van der Waals network of auxegens decreases from the initial self-expandability to two negatively small Poisson ratios on the xoy piane.

17

Pattern analysis of scan sheets using an array model

Bhattacharya P., Wu H.

Image Processing & Communications

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2002

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Vol. 8, no 3

31-38

EN

We present a framework for the identification and processing of scan sheets by using an array model. Certain submatrices of the arrays representing scan sheets contain the designated information for processing. Based on certain algebraic operations on arrays, eective techniques are formulated for processing of a scan sheet output matrix.

18

Spectral Energy and Age Distributions for 51 Globular Cluster Candidates

Ma J., Zhou X., Chen J., Wu H., Kong X., Jiang Z., Zhu J., Xue S.

Acta Astronomica

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2002

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Vol. 52, No. 4

453--470

EN

This paper is the fourth in a series presenting spectrophotometry of 51 globular cluster candidates, that were detected by Mochejska et al. in the nearby galaxy M33 using the data collected by the DIRECT project. The frames of M33 in this study were taken as a part of the BATC Multicolor Sky Survey. We obtained the spectral energy distributions of these candidates in 13 intermediate-band filters. By comparing the integrated photometric measurements with theoretical stellar population synthesis models of Bruzual and Charlot, we estimated their ages. The BC96 models provide the evolution in time of the spectrophotometric properties of simple stellar populations for a wide range of stellar metallicity. Our results show that half of the candidates are younger than 108 years. We also find that globular clusters formed continuously in M33 from ≈4×106 to 1010 years. Our results are in agreement with Chandar et al. who estimated ages for 35 globular clusters candidates from our list by comparing the photometric measurements to integrated colors from theoretical models by Bertelli et al. The Kolmogorov-Smirnov test shows that the maximum value of the absolute difference of estimated ages between Chandar et al. and us is 0.48, and the significance level probability is 100.00%.

19

Vision-based high accuracy work-piece inspection from profiles

Xu Z., Toncich D., Wu H.

Machine Graphics and Vision

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2001

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Vol. 10, No. 2

155-174

EN

The objective of the research documented herein was to investigate high-accuracy identification and measurement of a work-piece through edge detection, and to derive its three-dimensional properties from a profile of the work-piece image. A number of techniques for providing the transformation of the image are also described. The helix, helicoid and range of geometric entities have been selected to demonstrate the methodology and to highligh various aspect of the proposed techniques.