scholarly journals Compacting nanopowder materials by a pulse pressure generated by expanding plasma channel of a spark ignited by wire electrical explosion

2021 ◽  
Vol 24 (6) ◽  
pp. 1297-1310
Author(s):  
L. M. Chebotnyagin ◽  
V. V. Potapov ◽  
N. A. Ivanov ◽  
N. N. Ivanchik
Keyword(s):  
Powder Material ◽  
Pulse Pressure ◽  
Pressure Wave ◽  
High Speed ◽  
Pressure Pulse ◽  
Plasma Channel ◽  
Experimental Studies ◽  
Electric Explosion ◽  
Pressure Amplitude ◽  
Metal Pipes

The purpose of the article is to explore the possibilities of powder material compaction by the pressure pulse of an electric explosion of a conductor, establish a functional relationship between the parameters of the pressure pulse and an electrical technological installation for powder material compaction, select the parameters for pulse pressure amplitude and duration adjustment, and specify the design options of the working tool for powder material compaction. Analytical studies have been carried out on the basis of the method of formalized representation of the development of the process of pulse pressure wave formation and propagation where the latter is created by an expanding plasma channel of an electric spark in a transmitting medium initiated by an electric explosion of a wire. The simulation of high-speed de formation of the pipe wall under the action of the pulse pressure is carried out in the MATLAB software package. A scanning electron microscope is used to study the microstructure of the breakage of the compacted material with nanomodifiers. Based on the experimental studies on powder material compaction by the pulse pressure created by the expanding plasma channel of a spark initiated by an electric explosion of a wire when the current pulse f rom an electrotechnological installation is supplied to it, it has been determined that the magnitude and shape of the pressure pulse are most influenced by the parameters of this installation. Based on the obtained model studies, the optimal modes for compaction of nanomodified powders have been selected. The relationship is obtained between the parameters of the pulse pressure (Pm amplitude and pressure wave propagation form) and the electrotechnological installation (voltage, inductance, capacitance). It is proposed to use an acoustic-electric wave model to estimate the pressure that provides high-speed deformation of metal pipes, and to plot a deformation profile of metal pipes used for compaction. Analysis of SEM images of the fractures obtained in compact experiments has showed a high degree of particle compaction with the formation of a solid composite.

scholarly journals Numerical Analysis of the Aerodynamic Characteristics of the Open Line Intersection of Fast Freight Train with the Speed of 160 km/h

2021 ◽  
Vol 2125 (1) ◽  
pp. 012014
Author(s):  
Yue Zhang ◽  
Dongping Wang
Keyword(s):  
Pressure Wave ◽  
High Speed ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Pressure Amplitude ◽  
Freight Train ◽  
Measuring Point ◽  
Open Line ◽  
Volume Method ◽  
The Impact

Abstract With the increase of the speed of fast freight train, the aerodynamic effect of freight train in open-line intersection is more obvious. However, at present, there are many domestic researches on the aerodynamic characteristics of high-speed train open-line intersection, and almost no researches on fast freight train. Therefore, it is of great significance to study the aerodynamic characteristics of open line intersection of fast freight train in order to improve the safe operation of freight train in China. Based on the theory of computational fluid dynamics and finite volume method, uses FLUENT software to numerically calculate the three-dimensional, unsteady, compressible and turbulent flow fields in open line intersection of fast freight train at different speeds. The calculations results indicate that: when two freight trains meet, the amplitude of the pressure wave at the intersection side is the largest and the closer to the train bottom, the greater the amplitude of the pressure wave. The pressure amplitude of the bottom measuring point is 34.09% higher than that of the top measuring point. When two cars intersect at the same speed, the higher the speed, the greater the pressure amplitude and the pressure amplitude is proportional to the square of the speed. The fitting formula is: ΔP = cV2 ; When two trains intersect at different speeds, the impact on freight train with lower speed is greater than higher one.

scholarly journals Albuminuria intensifies the link between urinary sodium excretion and central pulse pressure in the general population: the Wakuya study

2021 ◽  
Author(s):  
Kaname Tagawa ◽  
Yusuke Tsuru ◽  
Katsumi Yokoi ◽  
Takanori Aonuma ◽  
Junichiro Hashimoto
Keyword(s):  
Cardiovascular Disease ◽  
Chronic Kidney Disease ◽  
Pulse Pressure ◽  
Augmentation Index ◽  
Sodium Intake ◽  
Urinary Sodium Excretion ◽  
Urinary Sodium ◽  
Pressure Amplitude ◽  
Excess Sodium ◽  
Central Pulse Pressure

Abstract Background Central pulse pressure is responsible for the hemodynamics of vital organs, and monitoring this parameter is important for cardiovascular disease prevention. Excess sodium intake and (micro)albuminuria (a manifestation of renal microvascular damage) are known to be strong predictors of cardiovascular disease. We sought to investigate the cross-sectional relationships among dietary sodium intake, albuminuria, and central pulse pressure in a general population cohort. Methods The subjects were 933 apparently healthy adults (mean age, 56 ± 10 years). Radial pressure waveforms were recorded with applanation tonometry to estimate mean arterial pressure, central pulse pressure, forward and backward pressure amplitudes, and augmentation index. The urinary sodium/creatinine and albumin/creatinine ratios were measured in spot urine samples. Results Both the urinary sodium/creatinine and albumin/creatinine ratios were positively correlated with central pulse pressure, even after adjusting for mean arterial pressure (P < 0.001). Moreover, both ratios had a synergistic influence on increasing the central pulse pressure independent of age, sex, estimated glomerular filtration rate, hyperlipidemia, and diabetes (interaction P = 0.04). A similar synergistic influence was found on the forward pressure amplitude, but not on the backward pressure amplitude or augmentation index. The overall results were not altered when the urinary albumin/creatinine ratio was replaced with the existence of chronic kidney disease. Conclusion (Micro)albuminuria strengthens the positive association between urinary sodium excretion and central pulse pressure and systolic forward pressure. Excess sodium intake may magnify the cardiovascular risk by widening the aortic pulsatile pressure, particularly in the presence of concomitant chronic kidney disease.

Iterative learning control of air pressure variation inside a high-speed train under the excitation of the tunnel pressure wave with a fixed-morphologic form

2021 ◽  
pp. 095440972110327
Author(s):  
Zhiying He ◽  
Chunjun Chen ◽  
Dongwei Wang ◽  
Chao Deng ◽  
Jia Hu ◽  
...  
Keyword(s):  
Iterative Learning Control ◽  
Pressure Wave ◽  
High Speed ◽  
Learning Control ◽  
Pressure Variation ◽  
Iterative Learning ◽  
Air Pressure ◽  
High Speed Train ◽  
Comfort Index ◽  
Simulation Signal

Based on the characteristics that the tunnel pressure wave has a fixed-morphologic form when the same train passes through the same tunnel, an applicational approach based on the iterative learning control (ILC) is developed, aiming at overcoming the drawbacks of the traditional strategy for controlling the air pressure variation inside a high-speed train carriage. To achieve the goal, the control system is mathematically modelled. Then, the problem is formulated. The task of suppressing the influence of the tunnel pressure wave on the air pressure inside the carriages is shifted as an ILC problem of tracking the comfort index with varying trial length. The algorithm of refreshing the control signal from trial to trial is determined and the process of ILC control is designed. Next, the convergence of the newly-developed applicational ILC algorithm is discussed and the algorithm is simulated by the simulation signal and field-test signal. Results show that the applicational ILC algorithm be more adaptable in handling the control of the air pressure inside carriage under the excitation of varying-amplitude, varying-scale and varying-initial-states tunnel pressure wave. Meanwhile, the matching with tunnel pressure wave makes the applicational ILC algorithm will take both the riding comfort and fresh air into consideration, which upgrades the performances when the high-speed train passing through long tunnels.

scholarly journals Identification of Sleeper Support Conditions Using Mechanical Model Supported Data-Driven Approach

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3609
Author(s):  
Mykola Sysyn ◽  
Michal Przybylowicz ◽  
Olga Nabochenko ◽  
Lei Kou
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Dynamic Interaction ◽  
Theoretical Research ◽  
Rolling Stock ◽  
Monitoring Methods ◽  
Beam Dynamic ◽  
Track Geometry ◽  
Data Driven Approach ◽  
Support Conditions

The ballasted track superstructure is characterized by a relative quick deterioration of track geometry due to ballast settlements and the accumulation of sleeper voids. The track zones with the sleeper voids differ from the geometrical irregularities with increased dynamic loading, high vibration, and unfavorable ballast-bed and sleeper contact conditions. This causes the accelerated growth of the inhomogeneous settlements, resulting in maintenance-expensive local instabilities that influence transportation reliability and availability. The recent identification and evaluation of the sleeper support conditions using track-side and on-board monitoring methods can help planning prevention activities to avoid or delay the development of local instabilities such as ballast breakdown, white spots, subgrade defects, etc. The paper presents theoretical and experimental studies that are directed at the development of the methods for sleeper support identification. The distinctive features of the dynamic behavior in the void zone compared to the equivalent geometrical irregularity are identified by numeric simulation using a three-beam dynamic model, taking into account superstructure and rolling stock dynamic interaction. The spectral features in time domain in scalograms and scattergrams are analyzed. Additionally, the theoretical research enabled to determine the similarities and differences of the dynamic interaction from the viewpoint of track-side and on-board measurements. The method of experimental investigation is presented by multipoint track-side measurements of rail-dynamic displacements using high-speed video records and digital imaging correlation (DIC) methods. The method is used to collect the statistical information from different-extent voided zones and the corresponding reference zones without voids. The applied machine learning methods enable the exact recent void identification using the wavelet scattering feature extraction from track-side measurements. A case study of the method application for an on-board measurement shows the moderate results of the recent void identification as well as the potential ways of its improvement.

Numerical and experimental studies on the thermal and static characteristics of multi-leaf foil thrust bearing

2021 ◽  
pp. 135065012110110
Author(s):  
Yu Guo ◽  
Yu Hou ◽  
Qi Zhao ◽  
Xionghao Ren ◽  
Shuangtao Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Failure Process ◽  
Experimental Studies ◽  
Elastic Model ◽  
Static Characteristics ◽  
Bearing Load ◽  
Foil Thrust Bearing ◽  
Cooling Air

Foil bearing is considered to be a promising supporting technology in high-speed centrifugal machinery. Due to the high-speed shearing effect in the viscous lubricant film, heat generation could not be ignored. In this paper, a thermo-elastic model of the multi-leaf foil thrust bearing is proposed to predict its thermal and static characteristics. In the model, modified Reynolds equation, energy equation, and Kirchhoff equation are solved in a coupling way. The contact area between the foil and welding plate is taken into account. Besides, the effect of cooling air on the bearing temperature is investigated. The ultimate load capacity and transient overload failure process of the bearing is analyzed and discussed. The effect of rotation speed on the bearing temperature is more obvious than that of the bearing load. The bearing temperature drops obviously by introducing the cooling air, and the cooling effect is improved with the supply pressure. The transient overload failure of the bearing occurs when the bearing load exceeds the ultimate value.

Optimal cross-sectional area distribution of a high-speed train nose to minimize the tunnel micro-pressure wave

2010 ◽  
Vol 42 (6) ◽  
pp. 965-976 ◽  
Author(s):  
Yo-Cheon Ku ◽  
Joo-Hyun Rho ◽  
Su-Hwan Yun ◽  
Min-Ho Kwak ◽  
Kyu-Hong Kim ◽  
...  
Keyword(s):  
Pressure Wave ◽  
High Speed ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
High Speed Train ◽  
Cross Sectional ◽  
Area Distribution

Interface Temperature Measurement and Experimental Studies of Super-High Speed Polishing of CVD Diamond Films

2010 ◽  
Vol 135 ◽  
pp. 271-276
Author(s):  
Shu Tao Huang ◽  
Li Zhou ◽  
Li Fu Xu
Keyword(s):  
Stainless Steel ◽  
Temperature Measurement ◽  
Temperature Rise ◽  
Diamond Film ◽  
High Speed ◽  
Experimental Studies ◽  
Pure Titanium ◽  
Cvd Diamond ◽  
Interface Temperature ◽  
Cvd Diamond Film

Super-high speed polishing of diamond film is a newly proposed method due to its outstanding features such as low cost and simple apparatus. The interface temperature rise is due to the friction force and the relative sliding velocity between the CVD diamond film and the polishing metal plate surface. In this paper, the interface temperature rise in super-high speed polishing of CVD diamond film was investigated by using the single-point temperature measurement method. Additionally, the influence of polishing plate material on the characteristics of super-high speed polishing has been studied. The results showed that cast iron is not suitable for super-high polishing, while both 0Cr18Ni9 stainless steel and pure titanium can be used for the super-high polishing of CVD diamond film. The quality and efficiency of polishing with 0Cr18Ni9 stainless steel plate is much higher than those of pure titanium, and the material removal rate could reach to 36-51 m/h when the polishing speed and pressure are 100 m/s and 0.17-0.31 MPa, respectively.

Characteristics of injection of diesel fuel, rapeseed oil and their mixtures in diesel engines of various types

2021 ◽  
pp. 167-178
Author(s):  
Keyword(s):  
Diesel Engine ◽  
Diesel Fuel ◽  
Diesel Engines ◽  
Rapeseed Oil ◽  
High Speed ◽  
Fuel Injection ◽  
Experimental Studies ◽  
Fuel Injector ◽  
High Speed Diesel ◽  
Engine Type

The necessity of adapting diesel engines to work on vegetable oils is justified. The possibility of using rapeseed oil and its mixtures with petroleum diesel fuel as motor fuels is considered. Experimental studies of fuel injection of small high-speed diesel engine type MD-6 (1 Ch 8,0/7,5)when using diesel oil and rapeseed oil and computational studies of auto-tractor diesel engine type D-245.12 (1 ChN 11/12,5), working on blends of petroleum diesel fuel and rapeseed oil. When switching autotractor diesel engine from diesel fuel to rapeseed oil in the full-fuel mode, the mass cycle fuel supply increased by 12 %, and in the small-size high-speed diesel engine – by about 27 %. From the point of view of the flow of the working process of these diesel engines, changes in other parameters of the fuel injection process are less significant. Keywords diesel engine; petroleum diesel fuel; vegetable oil; rapeseed oil; high pressure fuel pump; fuel injector; sprayer

Effect Of The Rib Inclination Angle On Liquid Film Spreading Over The Structured Surface

2015 ◽  
Vol 10 (1) ◽  
pp. 42-49
Author(s):  
Aleksandr Pavlenko ◽  
Oleg Volodin ◽  
Vladimir Serdyukov
Keyword(s):  
Liquid Film ◽  
Flow Rate ◽  
Inclination Angle ◽  
High Speed ◽  
Film Flow ◽  
Complex Geometry ◽  
Experimental Studies ◽  
Local Flow ◽  
Structured Packing ◽  
Film Spreading

Results of experimental studies on hydrodynamics of the film flow of liquid nitrogen over the surface of the single elements of structured packing are presented. The effect of inclination angle of the large ribs and perforation on the zones of liquid film spreading over the corrugated surface with microtexture at different Reynolds numbers of the film is shown based on a comparison of experimental data. It is shown that the angle of large rib inclination has a significant influence on redistribution of the local flow rate of liquid flowing on the surface with complex geometry. Analysis of results of the high-speed video revealed that in a vicinity of the vertical lateral edges of corrugated plates, the intense rivulet flows are formed, including those with separation from the film flow surface. This negative factor can lead to significant liquid accumulation and flow near the vertical edges of the structured packing and on the inner wall of the heat exchanging apparatuses and, finally, to a significant increase in the degree of maldistribution of local liquid flow rate over the crosssection, for instance, of the distillation columns.

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