Search results

The merits of the propeller hydrodynamic performance will directly affect the performance of the whole ship, so analysis of its hydrodynamic performance has become a necessary means of Marine propeller design, improvement and the checking.
Table 1 The size attribute, Material properties and boundary conditions parameter numerical value diameter 740mm leaf number 3 boss ratio 0.2 Experiments using reverse engineering technology to obtain the 3-d model of propeller and Pro/E software have been painting of flow unit model.
The definition of the boundary conditions will directly affect the accuracy of experimental results and authenticity, this experiment using professional software Gambit of boundary conditions and medium types are defined.
This is due to the leading edge contact with coming flow friction factor and other reasons lead to speed stagnation, make the pressure on the blade rise rapidly, with the increase of flow velocity pressure also decreases.
(Journal of mechanical engineering, 2010, 46(8):133-139)

Contact analysis is required material properties defining.
However, for contact problems, on the contrary, due to the higher-order unit may lead to equivalent nodal points of contact force oscillation to affect the contact convergence.
Third, meshing quality will seriously affect the calculation results.
Second, FKN is the scale factor of contact stiffness.
The value of FKN not only need to ensure the contact stiffness is large enough to ensure that exposure to maintain infiltration at a smaller level, but also avoid the contact stiffness is so large to cause the ill-condition of stiffness matrix and affect its convergence.

Introduction Porous ceramic materials offer a number of useful properties including low density, high-temperature stability, permeability, high surface area, and thermal shock resistance [1-3].
Many studies have been carried out about fabrication and property valuation of porous zirconia ceramics [7-10].
Zirconia powder content is the main factor affected on the density and the compressive strength.
Thermal and mechanical properties of porous Y-PSZ/zircon composites.
Microstructure and mechanical properties of porous yttria stabilized zirconia ceramic using poly methyl methacrylate powder.

INTRODUCTION Exposure of machines to variable loads leads to changes in the material properties caused by the influence of numerous phenomena.
They allowed to determine mechanical properties of steel: material yield point Re = 458 MPa (Re = Sy), material tensile strength Rm = 682 MPa (Rm = Su), Young's modulus E = 215000 MPa.
Another factor influencing behavior of the material are strains caused by the first load cycle, which refer to the strain of values Smax > Re or êSmin ê> Rec.
Obtaining consistent results can depend on the properties of the material used for the tests.
Tests of C45 steel have shown similar properties under tensile and compressive stresses, as shown in paper [2].

Single-Loop SVPWM Modulate Strategy for Permanent Magnet Synchronous Motor Control System Qixun ZHOU1, a, Yong ZHOU2,b and Yufeng ZHANG3,c 1 Department of Electrical & Control Engineering, Xi’an University of Science and Technology, China 2 School of Aeronautics, Northwestern Polytechnical University, Xi’an, China 3 School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an, China a zhouqixun029@163.com, byongstar@nwpu.edu.cn, c xkdzhangyufeng@qq.com Keywords: Permanent Magnet Synchronous Motor, Sine Pulse Width Modulation, Field Oriented Control, Single Loop, Space Vector Pulse Width Modulation.
Introduction The permanent magnet synchronous motor (PMSM) is widely applied in flexible manufacturing system, robot, office automation, office automation, numerical control machine and aeronautics and astronautics and other fields[1,2] with its such advantages as simple structure, small size, light weight, high power, high power factor, rotor free from heating problem, high overload capacity, small rotational inertia and small torque ripple and so on.
The PWM algorithm is simple, but the motor torque ripple is large, the winding availability is low and it is difficult to realize super-low speed operation; SPWM algorithm is easy to realize and the torque ripple is small and it may realize low speed smooth operation, but the SPWM starts from the angle of power and is pursuit of output of a three-phase symmetrical sine wave power supply of adjustable frequency and voltage, so the voltage utilization in PMSM system is low and the motor mechanical property is soft; FOC starts from the angle of motor and its objective is to make the motor generate the circular magnetic field and the flux linkage locus in motor gas-gap is close to round shape so as to reduce the torque ripple and core loss, but the control algorithm is complex and it needs to sample the motor real-time winding current and the hardware circuit is complex and the current noise is increased and the phase shift caused by filtering by use of hardware or software obviously affect
The test proves that the method has a higher system mechanical property when compared with SPWM drive and the control performance is close to that of the traditional FOC.
The stator phase current wave form has a good sine property, as shown in Fig. 5.

This is attributed to the fact that the CEB-FIP 1999 model assumes that autogenous shrinkage is largely dependent on compressive strength, and that the Jonasson and Hedlund model only considers W/B as the primary influencing factor for autogenous shrinkage.
In order to improve the prediction accuracy, the cement type factor γ of Tazawa and Miyazawa prediction model was modified by applying the test data to the prediction model.
Fig. 2 – Comparison of measured and predicted autogenous shrinkage from original and modified Tazawa and Miyazawa models at various days (1, 7, 14, 28, and 56 days) Conclusions Based on the test results of the experimental program and the comparisons among three autogenous shrinkage prediction models, the following conclusions can be drawn for SCC proportioned for precast, prestressed structural applications: l Autogenous shrinkage is highly affected by w/cm and binder content.
l The Tazawa and Miyazawa 1997 model with suggested modification for a cement factor can be used to estimate autogenous shrinkage of SCC designated for precast, prestressed structural applications.
J., Khayat, K.H., “Statistical Models to Predict Mechanical and Visco-Elastic Properties of SCC”, Proceedings of the 2nd International Symposium on Design, Performance and Use of Self-Consolidating Concrete, Beijing, China, June 5-7, pp 506-525, 2009

., Evropská 864, Brno 664 42, Czech Republic,**Brno University of technology, Faculty of Mechanical Engineering, Technická 2 Brno, Czech Republic *martin.nesvadba@danahermotion.com, **singule@fme.vutbr.cz Keywords: insulation system, life time, bus voltage, dv/dt ratio, peak voltage Abstract: The target of this paper is to evaluate influence of increased bus voltage of power converter on motor insulation system.
Therefore use of the extrapolations should be considered for relative thermal comparisons, not exact life performance, since many other factors impact exact winding life.
It is important to keep the motor temperature at the same level and perform periodical measurement of all key factors.
Both of these parameters affect the lifetime of insulation system and should be kept in focus for evaluation of results Acknowledgement The research has been supported by MSM0021630518 "Simulation Modeling of Mechatronic Systems".
Eichhorn: Engineering Dielectrics, Volume IIA, Electrical Properties of Solid Insulating Materials: Molecular Structure and Electrical Behavior, ASTM Special Technical Publication 783

The aim of this paper is to examine the properties of the S/S product and to assess its impact on the environment.
Laboratory testing was focused on screening those properties that may adversely affect the environment during the use of the product on the ground surface.
For this reason the properties of the S/S product were also tested two years after being manufactured.
This annex stipulates the determining factors to be the content of pollutants in the dry matter of waste and the results of ecotoxicological tests on waste, and it sets limiting values for these parameters.
Zuberova, Hodnoceni vyluhovych vlastnosti monolitickych odpadu (Evaluation of the leachability properties of monolithic wastes).

Peng et al. [31] studied the factors that influence the stability of nanofluids.
The test results showed that the most important factors affecting the stability of suspensions were the nanoparticles concentration, dispersant, viscosity of base liquid and pH value.
There are numerous factors such as heater or channel surface conditions (smooth or rough), heater size, shape, material, diameter and orientation, degree of surface wetting, sub cooling, inclusion of surfactants, and properties of liquid affecting heat transfer performance and bubble dynamics of pool and flow boiling [89 - 91].
The pool boiling is affected by the surface properties such as surface roughness, surface wettability, and surface contamination.
Yu, Influence factors on suspension stability of nanofluids, J.

Introduction Beam structure is used very commonly in mechanical engineering and advanced materials.
In 1972, Rice and Levy[7] proposed a linear spring model to make the three dimension problem into three dimensions which can be applied to calculate the stress intensity factor of surface crack.
As for the material properties, the modulus of elasticity E is 196109 Pa, the densityis 7860kg/m3 and the Poisson's ratio is 0.3.
For the second frequency, in addition to the principle mentioned above, the distance between node and crack also affects the natural frequency.
The methods mentioned in this paper could provide the theoretical, numerical and experimental basis for the identification of cracked materials, mechanical engineering and the relevant study.