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1

Modeling and experimental investigation of a controllable rotary fluid damper

Cao X., Zhou J., Yu M., Wang Y.

Archives of Mechanics

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2023

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Vol. 75, nr 4

493--516

EN

Controllable rotary fluid damper (CRFD) is an efficient and cheap energy dissipation device, which is used to reduce the impact of vibration in mechanical systems. In this paper, the CRFD controlled by a servo motor is developed to reduce the effects of vibrations in the helicopter flight control system. The dynamic mechanical characteristic of the CRFD is experimentally investigated by the MTS machine. Due to the complex factors such as high shear thinning rate and compressibility of the damping medium, inertia of moving parts and internal friction, the CRFD studied has highly nonlinear hysteresis characteristics. The accuracy of the damper modeling is of great significance for designing effective vibration reduction methods. Therefore, a new generalized viscous–nonlinear elastic model is proposed to track the mechanical characteristics of CRFD. On the basis of parameter sensitivity analysis, the proposed generalized viscous–nonlinear elastic model is modified. According to the identification results of the modified model, the main parameters are fitted as polynomial functions of motor rotation angle. Through error analysis between analytical torques and experimental torques, it is concluded that the modified generalized viscous–nonlinear elastic model has the smallest error compared with Kwok and Maxwell models, which indicates that the proposed modified model can accurately describe the mechanical characteristics of the CRFD under different working conditions.

2

Dynamic Measurement of Foam-Sized Yarn Properties from Yarn Sequence Images

Zhu B., Li Z., Cao X., Liu J., Gao W.

Autex Research Journal

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2018

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Vol. 18, no. 3

314--322

EN

Unlike the normal sizing method, the foam sizing had been proven to be a low-add-on technology. To investigate the effect of foam sizing, film thickness, sized-yarn evenness, and size penetration rate were necessary to evaluate the performances of foam-sized yarns. However, the conventional image analysis of sized-yarn cross sections primarily relied on artificial testing with a low efficiency. This paper proposed a novel dynamic method to measure the sized-yarn properties including film thickness, sized-yarn evenness, and size penetration rate based on yarn sequence images captured from a moving yarn. A method of dynamic threshold module was adopted to obtain threshold for segmenting yarns in the sequence images. K-means clustering algorithm was applied to segment pixels of the images into yarn and background. To further remove burrs and noise in the images, two judgment templates were carried out to extract the information of yarn core. The film thickness, sized-yarn evenness, and size penetration rate were measured based on the yarn core of each frame in sequence images. In order to compare with the experimental results of the dynamic method, the yarn properties of the same samples were tested by static and artificial testing. Results revealed that the proposed method could efficiently and accurately detect the film thickness, sized-yarn evenness, and size penetration rate.

3

Influence of alpha and gamma radiolysis on Pu retention in the solvent TBP/kerosene

Gao Y, Zheng W., Cao X., Chen S.

Nukleonika

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2014

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Vol. 59, No. 4

123--128

EN

In light of the issue of radiolysis of the solvent system in PUREX process, alpha and gamma radiation stability of tributyl phosphate (TBP)/kerosene (OK) have been studied in this paper, in which 238Pu dissolved in the organic phase and 60Co are selected as alpha and gamma irradiation sources, respectively. The amount of the degradation products not easily removed after the washing process has been measured by the plutonium retention. The effects of the absorbed dose, the TBP volume fraction, the cumulative absorbed dose and the presence of UO2 2+ and Zr4+ on the radiolysis of the solvents have been investigated. The results have indicated that the Pu retention increases with the increase of the absorbed dose after alpha or gamma irradiation, and is larger for the solvent containing less TBP. There is competition between UO2 2+ and Pu4+ to complex with the degradation products, and Zr4+ accelerates the radiolysis of the system.

4

Study on the Initiation Capacities of Conical Ring Booster Pellets

Hu L., Hu S., Cao X., Li J.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 3

335--348

EN

The insensitive main charge explosive is becoming an important part of modern weapon development. Insensitive main charge explosives generally have a high critical initiation pressure. The detonation pressure of a traditional cylindrical booster pellet is constant at a specific density and consequently has insufficient energy output to reliably initiate an insensitive main charge explosive. To ensure that this requirement could be achieved, the conical ring booster pellet was designed and optimized. Eight-point-synchronous explosive circuits were designed as appropriate to the sizes of the four booster pellets. The initiation processes of the four conical booster pellets equipped with the eight-point circuit were simulated using ANSYS/LY-DYNA software. The experimental measurements were performed in order to test the initiation capacities of these conical booster pellets. The results demonstrated that their initiation capacities are much better than the initiation capacity of a cylindrical booster pellet. The optimum size of the conical ring booster pellet is when the ratio of the inner to the upper diameter is 0.52, the ratio of the inner to the lower diameter is 0.44, and the ratio of the height to the lower diameter is 0.50.

5

Initiation Capacity of a New Booster Pellet

Hua L., Hu S., Cao X.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 1

157--170

EN

Insensitive munitions improve the survivability of both weapons and their associated platforms. All weapon systems contain an explosive train which needs to meet the insensitive munitions criteria but also to reliably initiate the main charge explosive. The traditional cylindrical booster pellet has insufficient energy output to reliably initiate an insensitive main charge explosive. To ensure that this requirement can be achieved, a new highly effective booster charge structure was designed. New booster pellets of four different sizes were investigated by numerical simulation and the one with the most powerful output was selected for experimental study. The results show that the new booster pellet has more initiation capacity than a cylindrical booster pellet with the same mass and pressed density. The convergence pressure of the new booster pellet is much higher than that of a cylindrical booster pellet with the same density.

6

Study on the Initiation Capacities of Two Booster Pellets

Hu L., Hu S., Cao X.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 3

261-272

EN

The appearance of insensitive main charges has created new requirements in the booster pellets of the detonation train, specifically, the output of the booster pellet must be strong enough to initiate the insensitive main charge. Traditional cylindrical booster pellets have great difficulty in meeting the demands of the insensitive main charge for reliable detonation. A four-point-synchronous explosive circuit and an eight-point-synchronous explosive circuit were designed to initiate two booster pellets, designed on the basis of shock initiation theory and effective charge theory, as well as the shaped charge effect theory. The results show that booster pellet 1 and booster pellet 2, under multi-point-synchronous explosive circuits, can initiate standard main charge pellets with less explosive mass than an ordinary cylindrical booster pellet. The initiation capacity of booster pellet 2 is better than that of booster pellet 1.

7

Basic research on determining optical properties of tissues in vivo by measuring diffuse reflectance with a charge-coupled device

Sun P., Cao X., Yang R., Xie F., Ding J., Zhang F.

Optica Applicata

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2011

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Vol. 41, nr 3

541--555

EN

We measured the absorption coefficient and the reduced scattering coefficient of Intralipid solution and human forearm tissues in vivo by measuring diffuse reflectance with a charge-coupled device, examining the techniques involved. The experimental results indicate that the error is less than or equal to 8% using the diffusion theory, under the condition that the reduced scattering coefficient is one order of magnitude greater than the absorption coefficient. The stability and precision of optical property measurements are significantly improved by using the multistep iterative fitting method and using the ring-zone-constraint method to determine the diffuse reflectance center. The efficiency of reverse algorithm is greatly enhanced by selecting a one-dimensional array on the straight line crossing both the entry point and the diffusion center for fitting.

8

Improvement of LiCoO2 cathodes by using Ag2V4O11 as an additive

Cao X., Liu J., Wan J., Xie L., Yan X., Wang H.

Materials Science Poland

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2009

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Vol. 27, No. 1

287--295

EN

LiCoO2/Ag2V4O11 composites were fabricated as cathode materials for lithium ion batteries by mechanical mixing of commercial LiCoO2 and Ag2V4O11 powders. The underlying principle of this idea was that the metallic silver particles were formed and acted as a conducting matrix when Ag2V4O11 cathode was electrochemically reduced which could significantly increase the electronic conductivity and decrease the polarization of cathode materials. The structure, morphology and electrochemical performance of bare LiCoO2 and LiCoO2/Ag2V4O11 composites were analyzed by XRD, SEM and charge-discharge test of CR2016 coin cells. The results show that a low amount of Ag2V4O11 additive can effectively enhance the discharge capacity and cycleability of LiCoO2. The composite containing 3 wt. % of Ag2V4O11 exhibits a higher discharge capacity and better cycle life than bare LiCoO2.

9

On modelling and analysis of piezoelectric smart structures by the finite element method

Gabbert U., Berger H., Koppe H., Cao X.

Applied Mechanics and Engineering

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2000

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Vol. 5, no 1

127-142

EN

In the paper, a general purpose finite element software for the simulation of piezoelectric material systems and controlled smart structures is presented. The equations of coupled electromechanical problems are given in a weak form, which are used for the development of 1D, 2D, 3D as well as multilayered composite shell elements. The smart structures finite element code includes static and dynamic analysis, where also controlled problems can be simulated. To demonstrate the capability of the simulation tool some test examples are reviewed.