ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2015-01-16
    Description: This paper attempts to introduce a numerical simulation procedure to simulate water-entry problems influenced by turbulent drag-reducing additives in a viscous incompressible medium. Firstly we performed a numerical investigation on water-entry supercavities in water and turbulent drag-reducing solution at the impact velocity of 28.4 m/s to confirm the accuracy of the numerical method. Based on the verification, projectile entering water and turbulent drag-reducing solution at relatively high velocity of 142.7 m/s (phase transition is considered) is simulated. The cross viscosity equation was adopted to represent the shear-thinning characteristic of aqueous solution of drag-reducing additives. The configuration and dynamic characteristics of water entry supercavity, flow resistance were discussed respectively. It was obtained that the numerical simulation results are in consistence with experimental data. Numerical results show that the supercavity length in drag-reducing soluti...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2011-06-07
    Description: This paper deals with the formation of Boron Carbide (B 4 C) powders from Na 2 B 4 O 7 +Mg+C system by self-propagating high-temperature synthesis (SHS) method. B 4 C without impurities could be obtained after the acid enrichment and distilled water washing. The reaction mechanism of SHS of B 4 C was proposed: the synthesis of B 4 C is a process involving the decomposition of Na 2 B 4 O 7 into the intermediate phase B 2 O 3 , which reacts with Mg and Carbon to form B 4 C.
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2011-09-22
    Description: Silicon nitride (Si 3 N 4 ) ceramics had been produced through pressureless sintering and hot-pressing sintering with MgSiN 2 -Y 2 O 3 or only MgSiN 2 as sintering aids. The influences of the amount of MgSiN 2 and Y 2 O 3 and sintering methods on the properties of Si 3 N 4 ceramics were investigated. The results show that the bend strength of Si 3 N 4 ceramic fabricated through pressureless sintering at 1820 °C for 4 h with 5.6 wt.% MgSiN 2 -15.8 wt.% Y 2 O 3 as sintering additive could achieve 839 MPa. However, the bend strength of Si 3 N 4 ceramic produced by hot-pressing sintering at 1750 °C for 1 h under uniaxial pressure of 20 MPa with 4.76 wt.% MgSiN 2 was 1149 MPa. The thermal conductivity of the Si 3 N 4 ceramic 2 3 4 could reach to 129 W·m −1 ·K 1 . The pre...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2018-07-31
    Description: In this paper, the mechanism of the wear of floating sleeve was analyzed firstly and according to three different pressure assumptions. The force and moment of the inner part of the floating sleeve were deduced respectively and are compared with the analog value. As a result, the force and moment of the inner part of the floating sleeve based on assumption which has minimal error can be a reference value. Then the expression of outboard force and moment were deduced. Based on the Gamultiobi() Function, the resultant and resultant moment of the eccentric 8-shaped floating sleeve were taken as objective functions. And the outer diameter, inner diameter, angle and elastic strength of the seal ring on the eccentric 8-shaped floating sleeve were taken as independent variables. With the restrained conditions of the width of seal ring, the values of the independent variables were obtained when the values of objective functions were minimum. At last, numerical simulation were carried ou...
    Print ISSN: 1755-1307
    Electronic ISSN: 1755-1315
    Topics: Geography , Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2018-07-31
    Description: The opening degrees of guide vane and runner blade are adjustable for Kaplan units. Therefore, the prototype unit performance is evaluated by cam curves to ensure the maximum efficiency points at different runner blade or guide vane angles. In this paper, the numerical simulation method is used to obtain the cohesive curves. The gravity force term is not ignored in the calculation, of which the effects are analysed not only on prototype performances, but also on internal flow characteristics such as the streamlines around runner blades, the pressure distributions and the head losses of each part.
    Print ISSN: 1755-1307
    Electronic ISSN: 1755-1315
    Topics: Geography , Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2018-07-31
    Description: Hydro-turbine generating units play vital roles in safe and stable operation of the whole grid. Hydropower units may meet with some fault such as wear, decreasing productivity and increasing noise due to outside disturbance such as defects, vibration and so on after running for a certain period of time. These problems have to be settled in time to ensure operating safety. In this paper, 19 typical vibration faults and 16 features are proposed and analyzed in detail in order to prepare for the diagnosis model establishment from the aspects of hydraulic, electromagnetic and mechanical factors. An expert system of hydropower unit based on GA-BP is established considering the 19 typical vibration faults and 16 features mentioned above. The results show that the model is accurate and practical. It is seen that the GA-BP model is more rapid and effective than the BP model from the comparisons of the simulation results between the GA-BP and the BP network models.
    Print ISSN: 1755-1307
    Electronic ISSN: 1755-1315
    Topics: Geography , Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2018-11-06
    Description: The paper studies the characteristics of runoff which can provide the basis for rational development and utilization of water resources in the Weihe River Basin (WRB). In this paper, sixteen typical hydrological stations in the WRB are selected, including six stations in the mainstream, eight in the south bank and two in the north bank of WRB. The ArcGIS and the Hawth’s Analysis Tools are used to calculate the fractal dimensions of the hydrological stations. The variations of annual and monthly runoff for stations are investigated using the fractal dimension during 1956-2015 in the WRB. The differences of fractal dimensions between the mainstream and the main tributaries located at the south bank and the north bank are compared. The results show that the runoff fractal dimension varies for different stations and months. In the WRB, the maximum monthly runoff fractal dimensions of stations are mainly in the flood season (June to October) and the minimum are mainly in the dry seas...
    Print ISSN: 1755-1307
    Electronic ISSN: 1755-1315
    Topics: Geography , Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2018-10-24
    Description: The effect of welding parameters on metallographic microstructure of aluminum bronze, interfacial microstructure and bonding strength of aluminum bronze and steel substrate has been studied. A cladding of aluminum bronze was obtained on the surface of medium carbon steel by CMT welding and short circuiting transfer welding. The microstructure of aluminum bronze and the interfacial microstructure of the interface between aluminum bronze and steel substrate have been systematically investigated. Sample 1-4 are α + ( α + γ 2 ) microstructure of typical aluminum bronze. As for Sample 5, iron-rich particles and dendrites were distributed on the α -Cu crystal matrix. The bonding strength of aluminum bronze and steel substrate has been collected according to the destructive testing method of the bimetallic bonding strength of sliding bearing. Among the five samples, Sample 4 and Sample 5 had the highest bonding strength (528.17MPa and 511.39Mpa, resp...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2017-12-30
    Description: The heat leakage of cryogenic transfer lines directly influences the performance of large-scale helium refrigerator. In this paper, a thermal model of cryogenic transfer line considering numerical simulation of support coupled with MLI was established. To validate the model, test platform of cryogenic transfer lines with the merits of disassembly outer pipe and changeable easily multi-layer insulation has been built. The experimental results of heat leakage through overall length of cryogenic transfer lines, support and multi-layer insulation were obtained. The heat leakages of multi-layer insulation, a support and the overall leakage are 1.02 W/m, 0.44 W and 1.46 W/m from experimental data, respectively. The difference of heat leakage of MLI between experiment and simulation were less than 5%. The temperature distribution of support and MLI obtained in presented model in good agreement with experimental data. It is expected to reduce the overall heat leakage of cryogenic transf...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2018-07-31
    Description: A proportional regulating valve is a hydraulic control valve that allows the output of the output oil parameter (pressure) to vary proportionally to the input electrical signal parameter (current or voltage). Due to the non-linearity of the regulating valve system and the problem of poor response characteristics, this paper studies the performance optimization problem of the system. In order to make the system work steadily, by adding iterative learning controller of Proportion-Integral-Derivative type, the system hydraulic pressure increases with the number of iterations gradually approaching the actual pressure required by the load. The simulation results show that the digital regulating valve based on Proportion-IntegralDerivative control law iterative learning control has fast response speed, high control precision and stable operation. So it can be used as an effective solution to achieve high-performance digital regulating valve.
    Print ISSN: 1755-1307
    Electronic ISSN: 1755-1315
    Topics: Geography , Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...