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1

Analytical solution of peridynamics for heat conduction with an external source

Fan S., Liu H., Peng X.

Archives of Mechanics

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2025

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Vol. 77, nr 4

401--429

EN

This study provides a novel analytical approach for solving one- and two-dimensional heat conduction problems with an external heat source within the peridynamic framework. By employing Duhamel’s principle, the inhomogeneous governing equation with an external source is transformed into a homogeneous equation, enabling the derivation of peridynamic analytical solutions through separation of variables. An innovation involves introducing a nonlocal factor by ensuring compatibility between the spatial functions in the peridynamic solution and their classical continuum mechanics counterparts. Numerical examples demonstrate the methodology’s effectiveness for both one- and two-dimensional heat conduction problems subjected to sinusoidal and constant external sources, and the nonlocal effect is measured based on the nonlocal factor. Unlike peridynamic systems without external sources, these examples reveal that the nonlocal factor appears not only in the exponential term but also in other components of the solution, indicating persistent nonlocal effects even as time approaches infinity. Furthermore, the analysis shows that the kernel function with n = 0 exhibits the strongest nonlocal influence, while n = 2 results in the weakest nonlocal behavior. The findings demonstrate that peridynamic analytical solutions for heat conduction can be systematically derived from classical continuum mechanics solutions through appropriate incorporation of the nonlocal factor. This work significantly expands the scope of peridynamic analytical solutions and offers new insights into nonlocal heat conduction phenomena, providing a valuable foundation for future studies in this field.

2

Ship Course Following and Course Keeping in Restricted Waters Based on Model Predictive Control

Liu H., Ma N., Gu X. C.

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

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2018

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Vol. 12, no. 2

305--312

EN

Ship navigation safety in restricted water areas is of great concern to crew members, because ships sailing in close proximity to banks are significantly affected by the so-called ship-bank interaction. The purpose of this paper is to apply the optimal control theory to help helmsmen adjust ships’ course and maintain the target course in restricted waters. To achieve this objective, the motion of a very large crude carrier (VLCC) close to a bank is modeled with the linear equations of manoeuvring and the influence of bank effect on the ship hydrodynamic force is considered in the model. State-space framework is cast in a Multiple-Input Multiple-Output (MIMO) system, where the offset-free model predictive control (MPC) is designed for course following and the linear quadratic regulator (LQR) is used for course keeping. Simulation results show that the control methods effectively work in ship course following and course keeping with varying ship-bank distances and water depths. The advantage of adopting speed variation as the second control input is obvious.

3

Numerical study of hydrodynamic derivatives and course stability under ship-bank interaction

Liu H., Ma N., Gu X. C.

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

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2018

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Vol. 12, no. 4

747--753

EN

Since ship-bank interaction affects the manoeuvrability of a ship navigating close to a bank, the determination of hydrodynamic derivatives is of great importance to assess the ship manoeuvrability. To obtain the hydrodynamic derivatives of the KVLCC2 model ship with different water depths and ship-bank distances, the simulation of PMM tests are carried out using an unsteady Reynolds-Averaged Navier–Stokes (RANS) based solver. Hybrid dynamic mesh technique is proposed to realize the simulation of pure yaw tests in confined water. Studies on the grid convergence and time-step-size convergence are firstly performed. Hydrodynamic derivatives for the ship in different water depths and ship-bank distances are compared. The course stability is investigated based on time-domain simulations and eigenvalue analysis, and the results show that the ship-bank interaction and shallow water effect have a remarkable influence on the course stability.

4

Quantitative analysis of the relationship between shear strength and fractal dimension of solidified dredger fill with different fly ash content under monotonic shear

Yang S., Liu W., Liu H.

Polish Maritime Research

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2018

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S 2

132--138

EN

The dredger fill of Shanghai Hengsha Island Dongtan is solidified by curing agents with different fly ash content, and the shear strength index of solidified dredger fill is measured by the direct shear test. The microscopic images of solidified dredger fill are obtained by using SEM. The microscopic images are processed and analyzed by using IPP, and the fractal dimension including particle size fractal dimension Dps, aperture fractal dimension Dbs and particle surface fractal dimension Dpr is calculated by fractal theory. The quantitative analysis of the relationship between shear strength index and fractal dimension of solidified dredger fill is done. The research results show that the internal friction angle and the cohesion are closely related to the fly ash content λ and the curing period T, and the addition of fly ash can improve the effect of curing agent; There is no obvious linear relationship between the internal friction angle and the three fractal dimensions; The smaller particle surface fractal dimension Dpr and particle size fractal dimension Dps, the larger aperture fractal dimension Dbs, the greater the cohesion, and the cohesion has a good linear relationship with three fractal dimensions, and the correlation coefficient R2 is above 0.91.

5

Passive localization for mixed-field moving sources

Gao C., Liu H.

Polish Maritime Research

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2018

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S 2

69--74

EN

Due to the mobility of underwater equipment, high-precision underwater positioning technology will face two technical challenges: dealing with mixed-field signals composed of near-field signals and far-field signals; adapting to variable component of mixed-field signals considering the mobility of equipment. Under this condition, an effective method based on MUSIC is addressed in this paper. After distinguishing far-field signal subspace from mixed-field signal subspace, estimations of DOAs and powers of far-field sources are carried out. Then the corresponding far-field and noise signal components can be eliminated from the signal subspace. After that, based on path-following algorithm, modified 2D-MUSIC is performed for DOA and range estimations of near-field sources. The performance of the proposed method is verified and compared with the other methods through computer simulations. Reasonable classification of source types and accurate localization estimation can be achieved by using the proposed method.

6

Synthesis, characterization of Hollandite Ag2Mn8O16 on TiO2 nanotubes and their photocatalytic properties for Rhodamine B degradation

Thabit M., Liu H., Zhang J., Wang B.

Polish Journal of Chemical Technology

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2018

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Vol. 20, nr 2

85--91

EN

In this research Ag2 Mn8 O16 nanocrysls/TiO2 nanotubes, photoelectrodes were successfully prepared through anodization and annihilation steps, followed by electrodeposition of MnO2 and Ag in a three electrodes cell. The obtained photoelectrodes were dried, then annealed for crystallization, the morphology and structure of the fabricated electrodes were characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The light absorption and harvesting properties were investigated through UV–visible diffuse refl ectance spectrum (DRS), photocatalytic performances were evaluated by degradation of 50 mL of Rhodamine B (5 mg L–1 ) under Xenon light irradiation for 2 h. Results illustrated that the fabricated photoelectrodes show remarkable photo-degradation properties of organic pollutants in aqueous mediums.

7

Preparation and Up-conversion Luminescence of Yb3+/Er3+/GZO Ceramics

Li G., Wang B., Wang R., Liu H.

Polish Journal of Chemical Technology

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2018

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Vol. 20, nr 3

15--19

EN

Yb3+/Er3+/GZO ceramics have been synthesized with high temperature solid-state method. The phase and structure of the Yb3+/Er3+/GZO ceramics were characterized by X-ray diffraction (XRD). The XRD pattern that following ions Yb3+ , Er3+ and Ga3+ were well doped into the ZnO lattice. Efficient visible up-conversion (UC) red and green emission were observed under 980 nm excitation. The mechanism of the UC luminescence is investigated on the basis of the UC luminescence emission spectra, the power curve and energy level diagram. The infl uence of doping ions to the intensity ratio of red to green is analyzed and high purity of red light (red/green = 29.9) is finally obtained.

8

Multi-parameter measurement under fiber bending based on directional resonance coupling in photonic crystal fibers

Tan C., Wang Q., Ding Y., Li H.-W., Wang M., Liu H.

Optica Applicata

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2018

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Vol. 48, nr 3

449--462

EN

A multi-parameter sensor with enhanced sensitivity based on magnetic fluids infiltrated photonic crystal fiber is proposed. The sensing performances are investigated using the mode coupling theory and finite element method. Four symmetrical defective channels are assembled into the photonic crystal fiber to produce two resonant transmission dips λCV and λCH in vertical and horizontal directions, respectively. Each dip can be split into two relatively shallow dips (λCV1, λCV2 or λCH1, λCH2) when the photonic crystal fiber is bent. Interestingly, the values of (λCH2 – λCH1) and (λCV2 – λCV1) are associated with corresponding bend-curvature but almost unaffected by external temperature or magnetic field. On the contrary, the values of (λCH2 + λCH1)/2 and (λCV2 + λCV1)/2 are sensitive to temperature or magnetic field regardless of the bending condition. Based on above characteristics and the dependence of the magnetic fluids refractive index on temperature and magnetic field, the proposed sensor can measure not only the bend-curvature and bend-direction, but also the temperature and magnetic field.

9

Microscale laser shock imprinting of micro-molds with different sizes and shapes

Yang H., Liu K., Liu H.

Optica Applicata

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2018

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Vol. 48, nr 4

671--686

EN

There are higher requirements for microstructures and high-precision components in microelectronics, photonics, sensors, optoelectronics and medical devices. For changing the traditional manufacturing methods with cumbersome process and complex equipment, researchers put forward a laser shock forming technique which can contribute to the metal forming with high precision and efficiency in recent years. So far, the laser shock forming needed high pulse energy and high energy. In this paper, nanosecond laser with high frequency and low pulse energy was adopted to make possible the aluminum foil forming on the copper micro-molds with different sizes and shapes. The deformations of aluminum foil were measured by SEM, optical profiler and AFM. Also, the deformation laws were analyzed by comparing imprinting results under different micro-molds. Lastly, stress distribution and deformation process of aluminum foil was investigated by numerical simulations.

10

A prediction method for load distribution in threaded connections

Zhang D., Gao S., Niu S., Liu H.

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 1

157--168

EN

A new method has been developed for predicting the load distribution along the thread portion of a bolt and nut connection. The calculated results were validated by comparison with three-dimensional finite element analysis and Yamamoto’s method. It was shown that the load distribution predicted by the model in this paper was in good agreement with the results from finite element model, and the load ratio on the first thread by the prediction model and finite element model was slightly larger than the results from Yamamoto’s method. In addition, the results of calculation and finite element analysis indicated that the decreasing of the lead angle could improve the load distribution, the increasing of the length of thread engaged could significantly improve the load bearing capacity of the first thread, and the adopting of a material with low stiffness for the nut with respect to the bolt could improve the load distribution slightly.

11

Simultaneous disturbance compensation and Hi/H∞ optimization in fault detection of UAVs

Liu H., Zhong M., Yang R.

International Journal of Applied Mathematics and Computer Science

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2018

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Vol. 28, no. 2

349--362

EN

This paper deals with the problem of robust fault detection (FD) for an unmanned aerial vehicle (UAV) flight control system (FCS). A nonlinear model to describe the UAV longitudinal motions is introduced, in which multiple sources of disturbances include wind effects, modeling errors and sensor noises are classified into groups. Then the FD problem is formulated as fault detection filter (FDF) design for a kind of nonlinear discrete time varying systems subject to multiple disturbances. In order to achieve robust FD performance against multiple disturbances, simultaneous disturbance compensation and Hi/H∞ optimization are carried out in designing the FDF. The optimality of the proposed FDF is shown in detail. Finally, both simulations and real flight data are applied to validate the proposed method. An improvement of FD performance is achieved compared with the conventional Hi/H∞-FDF.

12

Automatic identifying of maternal ECG source when applying ICA in fetal ECG extraction

Yu Q., Yan H., Song L., Guo W., Liu H., Si J., Zhao Y.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 3

448--455

EN

Independent component analysis (ICA) is usually used as a preliminary step for maternal electrocardiogram (ECG) QRS detection in fetal ECG extraction. When applying ICA to do this, a troublesome problem arises from how to automatically identify the separated maternal ECG component. In this paper we proposed a method called PRCH (short for Peak to peak entropy, R-R interval entropy, Correlation coefficient and Heart rate) for the automatic identifying. In the method, we defined four kinds of features, including amplitude, instantaneous heart rate, morphology and average heart rate, to characterize a signal, and determined some decision parameters through machine learning. Experiments and comparison with other three existed methods were given. Through taking metric F1 for evaluation, it showed that the proposed PRCH method has the highest identifying accuracy and generalization capability.

13

Tensile Damage Mechanism of 3-D Angle-Interlock Woven Composite using Acoustic Emission Events Monitoring

Ma Q., Wang K., Wang S. D., Liu H., Jin B. C., Jin L. M., Ma P.

Autex Research Journal

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2018

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Vol. 18, no. 1

46--50

EN

The quasi-static tensile damage behavior of one type of layer-to-layer 3-Dimensional Angle-interlock Woven Composite (3DAWC) was tested and analyzed in this paper. Incorporated with the acoustic emission (AE) events monitoring, the mechanical behavior of the 3DAWC under tensile loading condition was characterized. The Load-Extension curve, Load/AE events-Time curves occurred during the entire testing process and tensile damage modes were recorded to characterize and summarize the mechanical properties and damage mechanism of the 3DAWC subjected to tensile loading. It was found that the tensile damage of the 3DAWC could be summarized into 3 steps. And each step has a distinct primary damage mode. Moreover, the resin cracks, resin-yarn interface debonding and yarn breakages were the main damage modes for the 3DAWC.

14

Thermal Mechanical Stress Analysis of Ladle Lining with Integral Brick Joint

Chang W., Li G., Kong J., Sun Y., Jiang G., Liu H.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

659--666

EN

Based on the theory of heat transfer, the influence of expansion joints on the temperature and stress distribution of ladle lining is discussed. In view of the current expansion joint, the mathematical model of heat transfer and the three dimensional finite element model of ladle lining brick are established. By analyzing the temperature and stress distribution of ladle lining brick when the expansion joints are in different sizes, the thermal mechanical stress caused by the severe temperature difference can be reduced by the suitable expansion joint of the lining brick during the ladle baking and working process. The analysis results showed that the thermal mechanical stress which is caused by thermal expansion can be released through the 2 mm expansion joint, which is set in the building process. So we can effectively reduce the thermal mechanical stress of the ladle lining, and there is no risk of steel leakage, thus the service life of ladle can be effectively prolonged.

15

Improving Waveform Inversion using Modified Interferometric Imaging Condition

Guo X., Liu H., Shi Y., Wang W., Zhang Z.

Acta Geophysica

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2018

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Vol. 66, no. 1

71--80

EN

Similar to the reverse-time migration, full waveform inversion in the time domain is a memory-intensive processing method. The computational storage size for waveform inversion mainly depends on the model size and time recording length. In general, 3D and 4D data volumes need to be saved for 2D and 3D waveform inversion gradient calculations, respectively. Even the boundary region wavefield-saving strategy creates a huge storage demand. Using the last two slices of the wavefield to reconstruct wavefields at other moments through the random boundary, avoids the need to store a large number of wavefields; however, traditional random boundary method is less effective at low frequencies. In this study, we follow a new random boundary designed to regenerate random velocity anomalies in the boundary region for each shot of each iteration. The results obtained using the random boundary condition in less illuminated areas are more seriously affected by random scattering than other areas due to the lack of coverage. In this paper, we have replaced direct correlation for computing the waveform inversion gradient by modified interferometric imaging, which enhances the continuity of the imaging path and reduces noise interference. The new imaging condition is a weighted average of extended imaging gathers can be directly used in the gradient computation. In this process, we have not changed the objective function, and the role of the imaging condition is similar to regularization. The window size for the modified interferometric imaging condition-based waveform inversion plays an important role in this process. The numerical examples show that the proposed method significantly enhances waveform inversion performance.

16

Determination of the aglycon moieties of glycosidically bound compounds in Flos Chrysanthemi by GC × GC–TOFMS

Zhou Y., Huang G., Li X., Chen F., Liu H., Yang Y., Fan Z., Jiang J., Yang J.

Acta Chromatographica

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2018

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Vol. 30, no. 3

195--199

EN

A credible method for determination of the aglycon moieties of glycosidically bound aroma compounds in Flos Chrysanthemi by comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOFMS) has been proposed. The aglycon moieties of glycosidically bound aroma compounds were isolated using methyl-tert-butyl ether (MTBE) extraction following enzymatic hydrolysis. The GC × GC–TOFMS analysis was performed to comprehensively identify different forms of the released aroma components in Flos Chrysanthemi. The result shows that the limit of detection of the released aglycon moieties ranged from 0.3 to 3.1 ng/mL, the recovery of the released 1-octanol was better than 98.3%, and the intra-day and inter-day precisions of this method were 0.2 to 8.9% and 1.3 to 9.1%, respectively. The proposed method was applied to the analysis of four types of Flos Chrysanthemi (Chuju, Boju, Hangju, and Gongju). A total of 60 aglycon moieties of interest were identified in the four types of Flos Chrysanthemi. These aglycones mainly consisted of aliphatic, aromatic, monoterpene, C13-norisoprenoids, and miscellaneous compounds.

17

Nonlinear PTO effect on performance of vertical axisymmetric wave energy converter using semi-analytical method

Liu M., Liu H., Zheng X., Chen H., Wang L., Zhang L.

Polish Maritime Research

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2017

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S 3

49--57

EN

The wave energy, as a clean and non-pollution renewable energy sources, has become a hot research topic at home and abroad and is likely to become a new industry in the future. In this article, to effectively extract and maximize the energy from ocean waves, a vertical axisymmetric wave energy converter (WEC) was presented according to investigating of the advantages and disadvantages of the current WEC. The linear and quadratic equations in frequency-domain for the reactive controlled single-point converter property under regular waves condition are proposed for an efficient power take-off (PTO). A method of damping coefficients, theoretical added mass and exciting force are calculated with the analytical method which is in use of the series expansion of eigen functions. The loads of optimal reactive and resistive, the amplitudes of corresponding oscillation, and the width ratios of energy capture are determined approximately and discussed in numerical results.

18

Construction of waveform library in cognitive radar

Guo Y., Wu Y., Liu H.

Polish Maritime Research

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2017

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S 2

22--29

EN

Based on the thoughts of cognitive radar, Fractional Fourier Transform (FrFT) is used to generate a rotatable waveform libraries of Frank coded/Barker coded waveform in this paper. Then, the ambiguity function is used to analyze the delay resolution, Doppler resolution, delay side-lobe level, and Doppler side-lobe level of the waveform libraries and orthogonality of them is also analyzed. Furthermore, we proved theoretically that there is a fixed coordinate transformation between the waveforms of library and its origin waveform. Therefore, the Cramér-Rao low bound (CRLB) of motion parameters can be computed easily using the waveforms of the libraries, which facilitate the subsequent waveform scheduled work. Simulation results show that the library waveforms can reduce delay resolution to satisfy the different situations and can bring significant benefits for delay resolution, orthogonality and reuse interval.

19

Thermoelectric properties of Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 skutterudites prepared by HPHT method

Kong L., Ma H., Zhang Y., Guo X., Sun B., Liu B., Liu H., Liu B., Chen J., Jia X.

Materials Science Poland

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2017

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Vol. 35, No. 3

496--500

EN

N-type polycrystalline skutterudite compounds Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 with the bcc crystal structure were synthesized by high pressure and high temperature (HPHT) method. The synthesis time was sharply reduced to approximately half an hour. Typical microstructures connected with lattice deformations and dislocations were incorporated in the samples of Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 after HPHT. Electrical and thermal transport properties were meticulously researched in the temperature range of 300 K to 700 K. The Fe0.2Ni0.15Co3.65Sb12 sample shows a lower thermal conductivity than that of Ni0.15Co3.85Sb12. The dimensionless thermoelectric figure-of-merit (zT) reaches the maximal values of 0.52 and 0.35 at 600 K and 700 K respectively, for Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 samples synthesized at 1 GPa.

20

Large deformation and stability analysis of a cylindrical rubber tube under internal pressure

Sang J., Xing S., Liu H., Li X., Wang J., Lv Y.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 1

177--188

EN

Rubber tubes under pressure can undergo large deformations and exhibit a particular nonlinear elastic behavior. In order to reveal mechanical properties of rubber tubes subjected to internal pressure, large deformation analysis and stability analysis have been proposed in this paper by utilizing a modified Gent’s strain energy function. Based on the nonlinear elastic theory, by establishing the theoretical model of a rubber tube under internal pressure, the relationship between the internal pressure and circumferential principal stretch has been deduced. Meanwhile stability analysis of the rubber tube has also been proposed and the relationship between the internal pressure and the internal volume ratio has been achieved. The effects on the deformation by different parameters and the failure reasons of the rubber tube have been discussed, which provided a reasonable reference for the design of rubber tubes.