Wyniki wyszukiwania - Biblioteka Nauki

1

Application of computer identification and location algorithm in small far infrared target recognition of ship under surge interference

100%

Zhu R.

|

nr Special Issue S3

EN

The small far infrared target of ship in surge interference is easy to have visual deviation causing the low accuracy of target positioning and the bad target identification performance. In order to improve the accuracy of far small infrared targets recognition of ship under surge interference, this paper proposed far small infrared target recognition algorithm of ship based on distributed target position estimation and DOA location in computer vision model for constructing coherent distributed source array model of far small infrared target distribution of ship. This algorithm used MUSIC algorithm for the beamforming processing of far small infrared target echo model of ship. Combined with the adaptive filtering algorithm we carried out the surge interference suppression and the estimation of central direction of arrival and angle spread of far small infrared target of ship through multidimensional spectrum peak searching algorithm, realizing the joint estimation of distance of ship target, DOA and frequency parameters, so as to realize the accurate positioning and recognition of targets. Simulation results show that using this method for the far small infrared target recognition of ship under surge interference, the spectral peak sharpness of spectral peak search of target position is high, side-lobe suppression performance is good, which shows the high accuracy of target position estimation and location, the accuracy and anti-interference performance of far small infrared target recognition of ship is good, and has superior performance

2

Application of computer identification and location algorithm in small far infrared target recognition of ship under surge interference

100%

Zhu R.

|

2017

|

tom S 3

171--181

EN

The small far infrared target of ship in surge interference is easy to have visual deviation causing the low accuracy of target positioning and the bad target identification performance. In order to improve the accuracy of far small infrared targets recognition of ship under surge interference, this paper proposed far small infrared target recognition algorithm of ship based on distributed target position estimation and DOA location in computer vision model for constructing coherent distributed source array model of far small infrared target distribution of ship. This algorithm used MUSIC algorithm for the beamforming processing of far small infrared target echo model of ship. Combined with the adaptive filtering algorithm we carried out the surge interference suppression and the estimation of central direction of arrival and angle spread of far small infrared target of ship through multidimensional spectrum peak searching algorithm, realizing the joint estimation of distance of ship target, DOA and frequency parameters, so as to realize the accurate positioning and recognition of targets. Simulation results show that using this method for the far small infrared target recognition of ship under surge interference, the spectral peak sharpness of spectral peak search of target position is high, side-lobe suppression performance is good, which shows the high accuracy of target position estimation and location, the accuracy and anti-interference performance of far small infrared target recognition of ship is good, and has superior performance.

3

On autofrettage of cylinders by limiting circumferential residual stress based on Mises yield criterion

63%

Zhu R. , Zhu G.

|

2013

|

tom Vol. 51 nr 3

697--710

EN

The autofrettage technique is an effective and important measure to improve load-bearing capacity and safety and to even distributions of stresses for pressure vessels. Based on the classical fundamental theory on autofrettage and by theoretical analysis of residual stresses, the total stresses, the overstrain and the load-bearing capacity, etc., in view of the cylindrical pressure vessels with outside-to-inside radius ratio larger than the critical ratio, the laws contained in the autofrettage theory are revealed, the essential cause and reason for the obtained laws are analyzed, the inherent and meaning relations between various parameters in the autofrettage theory are brought to light, and the safe depth of the plastic zone (overstrain) as well as the conditions of loading or optimum operation conditions are found out. It is shown that under the optimum operation conditions, pressure vessels are not only safe but also economic, and the equations of the autofrettage theory are simplified greatly and are quite terse, as a result, the essential relations between various parameters in the autofrettage theory are distinct, and these equations are convenient for application in engineering practice.

4

Dry beneficiation and cleaning of chinese high-ash coarse coal utilizing a dense-medium gas-solid fluidized bed separator

51%

He J. , Tan M. , Zhu R. , Luo Z.

|

tom Vol. 52, iss. 2

662--675

EN

Dry dense-medium fluidized bed separation provides a new alternative approach for coal beneficiation and cleaning. An indicator of segregation degree Sash was proposed to evaluate the stratified performance of coal samples by bed density. Fluidization stability of the bed was greatly enhanced by mixing a certain amount (21.53%) of fine magnetite powder (< 0.15 mm) into the fluidized media, which indicated a uniform density distribution as well as slight fluctuations in bed. It was found that the favorable density-segregation performance of 3–13 mm coarse coal occurred with a static bed height of 80 mm and a superficial gas velocity of 11.84 cm/s. The optimal segregation degree values of 0.67, 0.74 and 0.76 were obtained for 3–6, 6–10 and 10–13 mm coal samples, respectively. Low-ash clean coal with yields of 50.79, 56.83 and 61.24% were effectively acquired by the dry separation for various coal size fractions, respectively. Probable error values of 0.07, 0.055 and 0.05 g/cm3 were achieved, indicating good separation performance.

5

Mechanical analysis of autofrettaged high pressure apparatus

51%

Zhu R. , Zhu G. , Mao A.

|

tom Vol. 55 nr 1

17--27

EN

High pressure apparatus is widely used in industries, the design of them depends on stress distributions in their walls. Most of high pressure apparatuses are made in form of cylinders. To raise load-bearing capacity and extend operation life for high pressure apparatus, the autofrettage technology is often used. To design autofrettaged high pressure apparatus, it is necessary to study characteristics of stresses in the wall of thick-wall cylinders, including residual stresses and total stresses, etc. In this study, through investigating the characteristics of stresses of cylinders subjected to internal pressure according to the maximum distortion strain energy theory, a set of simplified equations for residual stresses and total stresses are obtained, the safe and optimum load-bearing conditions for autofrettaged cylinders are found out, which are the basis for design of autofrettaged high pressure apparatus.

6

Research on new spectral reconstruction solutions for Fourier-transform spectrometer

51%

Li S. , Zhu R. , Li J.

Optica Applicata

|

2011

|

tom Vol. 41, nr 1

121--133

EN

The spectral reconstruction of Fourier transform spectrometer can be simply achieved by using a Fourier transform or a Fourier cosine transform. However, the traditional Fourier transform solution is carried out in the complex-number field and the result is also a complex-number sequence, which will introduce an extra-phase to the spectrum and lead to the inaccuracy of reconstructed spectral intensity. On the other hand, although researchers use a Fourier cosine transform to avoid the extra-phase problem effectively, this solution has a boundary condition problem which cannot be avoided and may also lead to the inaccuracy of the reconstructed spectral intensity. To solve the problem, an improved Hilbert transform reconstruction solution (IHTRS) and a Fourier conjugated correction reconstruction solution (FCCRS) are developed by analyzing traditional reconstruction solutions. The main thought of IHTRS is using a complex-number sequence to represent the real-number signal, doing the transform in the complex-number field, and extracting the real-number spectrum from the transform result in the end. The main thought of FCCRS is constraining the transform process in the real-number field, using the conjugated property of the Fourier transform, creating the conjugated symmetrical form of the original signal first and acquiring the conjugated symmetrical form of the real spectrum, and extracting the real spectrum from it in the end. The results of the two solutions are compared. By carrying out both the simulation and the experiment using a helium lamp, it can be concluded that the FCCRS is 3 times faster than IHTRS, while the reconstructed spectral intensity accuracy of IHTRS is 29% higher than FCCRS. Both of the two solutions can avoid either the extra-phase problem caused by a discrete Fourier transform (DFT) solution or the boundary condition caused by a discrete cosine transform (DCT) solution effectively and improve the reconstructed spectral intensity accuracy.

7

Surface Deformation due to Loading of a Layered Elastic Half-space : Constructing the Solution for a General Polygonal Load

45%

Bevis M. , Pan E. , Zhou H. , Han F. , Zhu R.

|

tom Vol. 63, no. 4

957--977

EN

We describe an algorithm for rapidly computing the surface displacements induced by a general polygonal load on a layered, isotropic, elastic half-space. The arbitrary surface pressure field is discretized using a large number, n, of equally-sized circular loading elements. The problem is to compute the displacement at a large number, m, of points (or stations) distributed over the surface. The essence of our technique is to reorganize all but a computationally insignificant part of this calculation into an equivalent problem: compute the displacements due to a single circular loading element at a total of m n stations (where m n is the product m × n). We solve this “parallel” problem at high computational speed by utilizing the sparse evaluation and massive interpolation (SEMI) method. Because the product m n that arises in our parallel problem is normally very large, we take maximum possible advantage of the acceleration achieved by the SEMI algorithm.

8

Stability of air nucleus in liquid water and cavitation inception on marine engineering

45%

Fu Q. , Chen M. , Wang X. , Zhu R. , Zhang G.

|

2018

|

tom S 3

111--119

EN

The micro air nucleus widely distributed in the ocean is a necessary condition for the cavitation of hydraulic machinery in seawater. In order to study the stability of air nucleus in seawater and cavitation inception, the computational domain of water molecules with air nucleus was studied using the method of molecular dynamics simulation, and the transient characteristics of air nucleus in liquid water were obtained. The key factors influencing nuclei stability were analyzed. The results showed that air nucleus with a certain mass could maintain the dynamic equilibrium in liquid water. The internal density of air nuclei had a critical value that allowed the nuclei to stably exist in water. The air nuclei mass was the decisive factor in its equilibrium volume in water, and the two were positively correlated. The internal density of air nuclei was negatively correlated with the nuclei radius when the nuclei was stable in water. Liquid surface tension was an important factor affecting the stability of the air nuclei. The larger the initial radius of nuclei, the smaller the water pressure, and the more likely the cavitation occurs.

9

A sedimentation model for particulate suspensions in liquid–solid fluidized beds with inclined channels

45%

Li Y. , Li N. , Qi X. , Zhang W. , Zhu R.

Physicochemical Problems of Mineral Processing

|

2018

|

tom Vol. 54, iss. 3

837--846

EN

The motion characteristics of mineral particles in a modified fluidized bed (mFB) with inclined plates have been studied both theoretically and experimentally. A particulate sedimentation model is built on the fluidization superficial velocity, terminal settling velocity, the device dimensions, the particle properties, and the volume fraction of the particulate suspensions in the inclined channel, which is to describe the motion behavior of particles in mono-disperse suspensions. The experimental particles are a mixture of silica and sand particles with the sizes in the range of 425 - 710 μm and 710 - 880 μm, respectively. Further, the model is extended to describe bi-disperse suspensions. The experimental system is established to be consistent with the theoretical arrangements, aiming to provide more accurate measurements. Specifically, the prediction results are in good agreement with the experimental data with the absolute deviation less than 11%. The results showed that the average solid volume fraction in the inclined channel fluctuates slightly for a given total solid inventory. The theoretical model is of certain practical significance for applications of this system to the classification, separation, and desliming of minerals.

10

Expression and localization of cannabinoid receptor 1 in rats’ brain treated with acute and repeated morphine

38%

Jin L. , Pan L. , Guo Y. , Zheng Y. , Nie Z. , Zhu R.

|

nr 3

EN

Morphine induces adaptive changes in gene expression throughout the reward circuitry of brain. Recent research has proven the functional interactions between opioid and endogenous cannabinoid system in the central nervous system (CNS). The cannabinoid receptor 1 (CBj-R) is one of the receptors that mediate the actions of cannabinoids and endocannabinoids in the CNS. Here, we investigated the expression of CBrR in mRNA and protein levels in the brains of rats treated with acute and repeated morphine. Three groups of rats received intraperitoneal injections (ip injections) of saline, acute morphine (10 mg/ kg) and repeated morphine (10 mg/kg, twice daily for 12 consecutive days), and the mRNA levels and protein expressions of CB1-R were examined. RT-PCR and western blot analyses supported that both mRNA and protein levels of CB1-R in cortex, cerebellum and hippocampus were increased by repeated morphine treatment. However, the mRNA level in cerebellum was down-regulated only after acute morphine treatment and would returned to basal levels later. We used immunohistochemistry techniques to determine the functional expression of CB1-R in morphine treated rat's brain. Enzyme- Linked Immunosorbent Assay (ELISA) revealed the significant increase of cytokine (IL-ip, IL-6) levels in the repeated morphine treatment rats' cortex and hippocampus regions, which are both addiction-related brain areas. In addition, the results from RT-PCR and western blot assay indicated that the expression of CB1-R was directly increased by morphine treatment in vitro. All the results indicated that the CB1-R expression could be changed by morphine exposure and it might be involved in neural immune function, which provided a potential target for neurogenic disease treatment.

11

Stability of air nucleus in liquid water and cavitation inception on marine engineering

38%

Fu Q. , Chen M. , Wang X. , Zhu R. , Zhang G. , Yu J.

|

nr Special Issue S3

EN

The micro air nucleus widely distributed in the ocean is a necessary condition for the cavitation of hydraulic machinery in seawater. In order to study the stability of air nucleus in seawater and cavitation inception, the computational domain of water molecules with air nucleus was studied using the method of molecular dynamics simulation, and the transient characteristics of air nucleus in liquid water were obtained. The key factors influencing nuclei stability were analyzed. The results showed that air nucleus with a certain mass could maintain the dynamic equilibrium in liquid water. The internal density of air nuclei had a critical value that allowed the nuclei to stably exist in water. The air nuclei mass was the decisive factor in its equilibrium volume in water, and the two were positively correlated. The internal density of air nuclei was negatively correlated with the nuclei radius when the nuclei was stable in water. Liquid surface tension was an important factor affecting the stability of the air nuclei. The larger the initial radius of nuclei, the smaller the water pressure, and the more likely the cavitation occurs

12

The cavitation nuclei transient characteristics of Lennard-Jones fluid in cavitation inception

38%

Fu Q. , Zhang B. , Zhao Y. , Zhu R. , Liu G. , Li M.

|

2018

|

tom S 2

75--84

EN

In the field of ocean engineering, cavitation is widespread, for the study of cavitation nuclei transient characteristics in cavitation inception, we applied theoretical analysis and molecular dynamics (MD) simulation to study Lennard-Jones (L-J) fluid with different initial cavitation nuclei under the NVT-constant ensemble in this manuscript. The results showed that in cavitation inception, due to the decrease of liquid local pressure, the liquid molecules would enter the cavitation nuclei, which contributed to the growth of cavitation nuclei. By using molecular potential energy, it was found that the molecular potential energy was higher in cavitation nuclei part, while the liquid molecular potential energy changes greatly at the beginning of the cavitation nuclei growth. The density of the liquid and the surface layer changes more obvious, but density of vapor in the bubble changes inconspicuously. With the growth of cavitation nuclei, the RDF peak intensity increased, the peak width narrowed and the first valley moved inner. When cavitation nuclei initial size reduced, the peak intensity reduced, the corresponding rbin increased. With the decrease of the initial cavitation nuclei, the system pressure and total energy achieved a balance longer, and correspondingly, they were smaller. In addition, at the beginning of the cavitation nuclei growth, the total energy and system pressure changed greatly.