Wyniki wyszukiwania - Biblioteka Nauki

1

Simulation on vessel intelligent collision avoidance based on artificial fish swarm algorithm

100%

Li W. , Ma W.

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2016

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tom S 1

138--143

EN

TAs the rapid development of the ship equipments and navigation technology, vessel intelligent collision avoidance theory was researched world widely. Meantime, more and more ship intelligent collision avoidance products are put into use. It not only makes the ship much safer, but also lighten the officers work intensity and improve the ship’s economy. The paper based on the International Regulation for Preventing Collision at sea and ship domain theories, with the ship proceeding distance when collision avoidance as the objective function, through the artificial fish swarm algorithm to optimize the collision avoidance path, and finally simulates overtaking situation, crossing situation and head-on situation three classic meeting situation of ships on the sea by VC++ computer language. Calculation and simulation results are basically consistent with the actual situation which certifies that its validity.

2

Separation of two isomers of benzocarbazoles by ß-cyclodextrin modified micellar electrokinetic capillary chromatography

80%

Shi X. , Ma W. , Chen D.

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tom Vol. 46, No. 3

433-438

EN

To optimize the separation conditions of the two isomers of benzocarbazoles, micellar electrokinetic capillary electrophoresis (MECC) was employed in this study. In this procedure, a fused silica capillary of 57 cm x 50 um (50 cm to detector) was used. Running buffer was 5.0 mmol 1(-1) aqueous sodium tetraborate solution containing 70 mmol1 (-1) sodium dodecyl sulfate (pH9.16) and 20 mmol 1(-1) p-cyclodextrin. The separation voltage and the pH value of the buffer were optimized. At the optimized separation conditions, the two isomers were separated well within 10 min. It is thus proved that MECC is an effective method for oil chemical exploration.

PL

W celu optymalizacji rozdzielania dwóch izomerów benzokarbazoli zastosowano mice-larną elektrokinetyczną kapilarną chromatografię. Stosowano kapilary z topionego kwarcu o wymiarach 57 cm x 50 urn, przy odległości 50 cm do detektora. Jako bufor zastosowano 5 mmol 1(-1) roztwór wodny tetraboranu sodowego, zawierający 70 mmol 1(-1)dodecylosiarczan sodowy (pH 9,16) i 20 mmol 1(-1) p-cykodekstrynę. Optymalizowano napięcie i wartość pH buforu. W wybranych warunkach rozdzielania oba izomery ulegają dobremu rozdzieleniu w ciągu 10 min co może być wykorzystane przy identyfikacji złóż ropy.

3

The multiple dimension of water in the designing and governance of public spaces. The case of Shanghai West Bund Project compared to other Western Waterfronts renovations

80%

Semprebon G. , Ma W. , Fabris L. M. F.

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tom nr 22

22--27

EN

In 2010, the municipality of Shanghai started the “Huangpu River Comprehensive Development Plan”, a large regeneration initiative including the Expo site, targeted to revitalize the river banks and generally the urban environment, making Xuhui waterfront one of the six key construction areas of the 12th Five-Year Plan in Shanghai. Formerly one of the largest industrial districts, the so-called West Bund area has experienced a process of substantial transformation, currently still ongoing. Particular attention has been paid to the rehabilitation of the riverside, as a source of landscape enhancement, providing a system of open spaces and public facilities able to meet the dweller’s demands and to attract touristic fluxes. For this reason, the West Bund Project represents one of the most relevant regeneration initiative currently taking place in Shanghai. This paper aims to investigate, starting from this specific case-study, the role of water in the definition of cultural and natural elements, revealing new perspectives for the revitalization of the urban environment.

4

Test research on the resistance performance of high-speed trimaran planing hull

80%

Ma W. , Sun H. , Zou J. , Yang H.

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tom 20

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nr 4

EN

In order to identify high-speed navigation ability of trimaran planing hull, as well as investigate the characteristics of its resistance and hull form, ship model tests were conducted to measure resistance, trim and heaving under different displacements and gravity centre locations. The test results were then used to study the inﬂuence of spray strips on resistance and sea-keeping qualities. Moreover, different planing surfaces were compared in the model tests which helped to look into inﬂuence of steps on hull resistance and its moving position. Also, the resistance features of monohull and trimaran planing hulls, both with and without steps, were compared to each other. From the tests it can be concluded that: the two auxiliary side hulls increase aerodynamic lift at high-speed motion, which improves the hydrodynamic performance; the trimaran planing hull has also excellent longitudinal stability and low wave-making action; when Fr∇ > 8, its motion is still stable and two distinct resistance peaks and two changes of sailing state (the second change is smaller) appear; spray strips are favourable for sea-keeping qualities at high speed. The change trends before the second resistance peak as to the resistance and sailing behaviour of trimaran planing hull without steps are the same as for monohull planing hull without steps. but when steps in both hulls exist the change trends are different; more speciﬁcally: trimaran planing hull with steps has only one resistance peak and its resistance increases along with its speed increasing, and the resistance is improved at the increasing speed as the number of steps increases

5

Test research on the resistance performance of high-speed trimaran planing hull

80%

Ma W. , Sun H. , Zou J. , Yang H.

|

tom nr 4

45--51

EN

In order to identify high-speed navigation ability of trimaran planing hull, as well as investigate the characteristics of its resistance and hull form, ship model tests were conducted to measure resistance, trim and heaving under different displacements and gravity centre locations. The test results were then used to study the influence of spray strips on resistance and sea-keeping qualities. Moreover, different planning surfaces were compared in the model tests which helped to look into influence of steps on hull resistance and its moving position. Also, the resistance features of monohull and trimaran planing hulls, both with and without steps, were compared to each other. From the tests it can be concluded that: the two auxiliary side hulls increase aerodynamic lift at high-speed motion, which improves the hydrodynamic performance; the trimaran planing hull has also excellent longitudinal stability and low wave-making action; when Fr∇> 8, its motion is still stable and two distinct resistance peaks and two changes of sailing state (the second change is smaller) appear; spray strips are favourable for sea-keeping qualities at high speed. The change trends before the second resistance peak as to the resistance and sailing behaviour of trimaran planing hull without steps are the same as for monohull planing hull without steps. but when steps in both hulls exist the change trends are different; more specifically: trimaran planing hull with steps has only one resistance peak and its resistance increases along with its speed increasing, and the resistance is improved at the increasing speed as the number of steps increases.

6

Numerical simulations of linearly stratified flow past submerged bodies

71%

Ma W. , Li Y. , Ding Y. , Hu K. , Lan L.

|

2018

|

tom S 3

68--77

EN

In this study, a methodology was presented to predict density stratified flows in the near-field of submerged bodies. The energy equation in temperature form was solved coupled with momentum and mass conservation equations. Linear stratification was achieved by the definition of the density as a function of temperature. At first, verifications were performed for the stratified flows passing a submerged horizontal circular cylinder, showing excellent agreement with available experimental data. The ability of the method to cope with variable density was demonstrated. Different turbulence models were used for different Re numbers and flow states. Based on the numerical methods proposed in this paper, the stratified flow was studied for the real scale benchmark DAPRA Suboff submarine. The approach used the VOF method for tracing the free surface. Turbulence was implemented with a k − ω based Detached Eddy Simulation (DES) approach. The effects of submarine speed, depth and density gradient on the free surface wave pattern were quantitatively analyzed. It was shown that, with the increasing of the speed of the submarine, the wavelength and wave height of the free surface wave were gradually increasing. The wave height of the free surface wave was gradually reduced as the submarine’s depth increased. Relative to the speed and submarine depth, the changes of the gradient density gradient have negligible effects on the free surface wave field.

7

A simulation study on optimal oil spraying mode for high-speed rolling bearing

71%

Pang B. T. , Li J. S. , Liu H. B. , Ma W. , Xue Y. J.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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tom Vol. 31, nr 2

553-557

EN

Purpose: In this study, a numerical simulation model of the oil spraying system is established. Design/methodology/approach: Spraying lubrication is a common form of the rolling bearing lubrication. But with the increase of the bearing speed, the roller cage is frequently shattered, which may lead to failure of the bearing. The shatter of roller cage may be related to the spraying mode of oil. For high-speed rolling bearing, the roller cage shatter can be cracked due to the shortage of oil, caused by lubricating oil not sprayed into the roller cage shatter. This condition can be ameliorated by changing the spraying mode of oil supply system. The model considered the spraying speed, spraying angle, oil pressure, oil viscosity, structure of roller cage shatter, rotating speed as the main parameters. By optimization, the best way of oil spraying was obtained which can meet lubrication requirement of high-speed rolling bearing. At the same time, the numerical simulation results also revealed that the optimal spraying mode is different for different rolling bearings. Findings: The simulating results indicate that due to the effect of the air pressure and airflow thickness, the optimal spraying position is at a region closer to the inner ring of the bearings. Practical implications: This paper will provide useful information to applying numerical simulation of the oil spraying system. Originality/value: The computer simulation allows to better understand the interdependence between parameters of process and choosing optimal solution.

8

Numerical simulations of linearly stratified flow past submerged bodies

71%

Ma W. , Li Y. , Ding Y. , Hu K. , Lan L.

|

nr Special Issue S3

EN

In this study, a methodology was presented to predict density stratified flows in the near-field of submerged bodies. The energy equation in temperature form was solved coupled with momentum and mass conservation equations. Linear stratification was achieved by the definition of the density as a function of temperature. At first, verifications were performed for the stratified flows passing a submerged horizontal circular cylinder, showing excellent agreement with available experimental data. The ability of the method to cope with variable density was demonstrated. Different turbulence models were used for different Re numbers and flow states. Based on the numerical methods proposed in this paper, the stratified flow was studied for the real scale benchmark DAPRA Suboff submarine. The approach used the VOF method for tracing the free surface. Turbulence was implemented with a k − ω based Detached Eddy Simulation (DES) approach. The effects of submarine speed, depth and density gradient on the free surface wave pattern were quantitatively analyzed. It was shown that, with the increasing of the speed of the submarine, the wavelength and wave height of the free surface wave were gradually increasing. The wave height of the free surface wave was gradually reduced as the submarine’s depth increased. Relative to the speed and submarine depth, the changes of the gradient density gradient have negligible effects on the free surface wave field

9

A new anti-counterfeiting method: fluorescent labeling by safranine T in tobacco seed

71%

Guan Y. , Hu J. , Li Y. , Ma W. , Zheng Y.

Acta Physiologiae Plantarum

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2011

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tom 33

|

nr 4

EN

Counterfeit seeds cause a large loss in seed industry and crop production. Present study was undertaken to find a new anti-counterfeiting technology by labeling seeds with a fluorescent compound, safranine T (ST). Response surface analysis (RSA) experiment with two factors (ST concentration and seed soaking time) of 14 combinations was performed to investigate the ST effects on seed vigor and fluorescence showing in seedlings of two tobacco varieties, MS Yunyan 85 and Honghua Dajinyuan. After soaking in ST solutions, tobacco seeds were germinated for 16 days, then the germination index (GI), vigor index (VI), length of roots and shoots were determined. The optimum combinations of ST concentration and soaking time on GI, VI and length of shoots and roots were 0.57–0.69 mg/ml and 6.77–9.34 h for MS Yunyan 85 and 0.51–0.80 mg/ml and 5.81–7.39 h for Honghua Dajinyuan, respectively. Meanwhile, tobacco seedlings, treated with ST solutions from 0.3 to 1.5 mg/ml showed obviously fluorescence under illumination of green light. It suggests that soaking tobacco seeds in safranine T solution of suitable concentration can be used as a labeling technique for anti-counterfeiting in tobacco seeds.

10

Dynamic response analysis among environmental regulation, technological progress and water resource consumption in China’s textile industry

61%

Li Y. , Wang Y. , Ding L. , Ke L. , Ma W. , Yang Y.

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nr 4

11

Atmospheric dry deposition to natural water of wetland in suburban Beijing

61%

Wang Y. , Mo L. , Cong L. , Zhai J. , Ma W. , Zhang Z.

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nr 2

12

Motion prediction of catamaran with a semi-submersible bow in wave

61%

Sun H. , Jing F. , Jiang Y. , Zou J. , Zhuang J. , Ma W.

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nr 1

EN

Compared with standard vessels, a slender catamaran with a semi-submerged bow (SSB) demonstrates superior seakeeping performance. To predict the motion of an SSB catamaran, computational fluid dynamics methods are adopted in this study and results are validated through small-scale model tests. The pitch, heave, and vertical acceleration are calculated at various wavelengths and speeds. Based on the overset grid and motion region methods, this study obtains the motion responses of an SSB catamaran in regular head waves. The results of the numerical studies are validated with the experimental data and show that the overset grid method is more accurate in predicting the motion of an SSB catamaran; the errors can be controlled within 20%. The movement data in regular waves shows that at a constant speed, the motion response initially increases and then decreases with increasing wavelength. This motion response peak is due to the encountering frequency being close to the natural frequency. Under identical sea conditions, the motion response increases with the increasing Froude number. The motion prediction results, that derive from a shortterm irregular sea state, show that there is an optimal speed range that can effectively reduce the amplitude of motion

13

Motion prediction of catamaran with a semisubmersible bow in wave

61%

Sun H. , Jing F. , Jiang Y. , Zou J. , Zhuang J. , Ma W.

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2016

|

tom nr 1

37--44

EN

Compared with standard vessels, a slender catamaran with a semi-submerged bow (SSB) demonstrates superior seakeeping performance. To predict the motion of an SSB catamaran, computational fluid dynamics methods are adopted in this study and results are validated through small-scale model tests. The pitch, heave, and vertical acceleration are calculated at various wavelengths and speeds. Based on the overset grid and motion region methods, this study obtains the motion responses of an SSB catamaran in regular head waves. The results of the numerical studies are validated with the experimental data and show that the overset grid method is more accurate in predicting the motion of an SSB catamaran; the errors can be controlled within 20%. The movement data in regular waves shows that at a constant speed, the motion response initially increases and then decreases with increasing wavelength. This motion response peak is due to the encountering frequency being close to the natural frequency. Under identical sea conditions, the motion response increases with the increasing Froude number. The motion prediction results, that derive from a shortterm irregular sea state, show that there is an optimal speed range that can effectively reduce the amplitude of motion.

14

LncRNA H19 promotes the differentiation of bovine skeletal muscle satellite cells by suppressing Sirt1/FoxO1

61%

Xu X. , Ji S. , Li W. , Yi B. , Li H. , Zhang H. , Ma W.

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tom 22

15

Ecological heavy metals risk of saline lake sediments in Northwestern China

51%

Li D. , Jiang J. , Yan C. , Zhang M. , Xiang Y. , Ma W. , Jia H. , Zhao X.

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nr 4