Transition Position Research Articles

Effects of flange wear on dynamic vehicle-turnout interaction

Long-term investigations have revealed incidences of severe flange wheel wear in the field. Slight changes in the profile shape will lead to changes in the geometric relationship between wheel and rail, hence affecting the dynamic wheel-rail interaction. The turnout is an essential piece of track equipment for carrying out train transfer or cross line operation. In turnouts, the rail profile changes throughout the structure, and the wheel load transfers from one rail component to the next, resulting in a complex wheel/rail relationship. This paper investigates the effect of flange wear on the wheel-rail interaction as the vehicle switches into the turnout track in a diverging movement. A coupling model for a high-speed flexible turnout and a multi-rigid vehicle is established, and the dynamic contact trajectories between wheel and rail, the vibration energy of the rail, the lateral wheel-rail force, rail wear, and car body driving stability are analyzed. The results show that the wheel transition position is shifted backward due to the flange wear, and a less sharp impact occurs with a worn flange profile during wheel load transition in the switch panel, which improves lateral wheel-turnout interaction and the rail wear. Worn flange profiles give a large flangeway clearance, which is not conducive to the smooth operation of vehicles in the diverging route of turnouts.

Effect of CO-to-H2 ratio on syngas flame behaviors in a micro flow reactor with controlled wall temperature gradient

Flame characteristics of CO/H2/O2/N2 mixture (O2:N2 = 1:7) with different CO/H2 ratios in a micro-channel with a controlled wall temperature gradient were investigated through numerical simulation. Five flame regimes were identified and their global diagram was drawn. The influence of CO/H2 ratio on two typical flame dynamics (one is stable and the other is unstable), i.e., “coexisting upstream normal flame (UNF) and downstream weak flame (DWF)” and “uninterrupted flame with repetitive extinction and ignition (UFREI)”, were discussed. It is revealed that in the UNF-DWF regime, a higher H2 proportion can strengthen OH generation in the UNF through H2-OH and H-HO2-OH reaction paths, which causes the UNF to propagate upstream. However, the upstream lower wall temperature results in weaker near-wall reaction intensity for the UNF, which brings about more CO residual and thus enhances the DWF. For the UFREI regime, both the period and the propagation distance of flame dynamics are reduced with the augmentation of CO/H2 ratio because of the weakened flame intensity. Moreover, the characteristic flame positions are also affected by the CO/H2 ratio. In details, the farthest position of UFREI moves upstream while the transition position slightly shifts downstream as the CO/H2 ratio is increased, which is substantially affected by the transport of residual fuel after the extinction of UFREI. In summary, the present investigation unraveled the complicated influence of CO/H2 ratio on the syngas flame dynamics in a micro-channel with a controlled wall temperature gradient.

Single nucleotide polymorphism in cytochrome B oxidase gene among indigenous cattle breeds of Tamil Nadu

The present study was carried out to validate the single nucleotide polymorphism (SNP) in mitochondrial gene- cytochrome b oxidase at 14,716 bp (C to T transition) position obtained from whole genome sequence data of indigenous cattle breeds at Department of Animal Genetics and Breeding, Madras Veterinary College, Tamil Nadu. A total of 288 animals, viz. Alambadi (16), Bargur (99), Kangayam (54), Pulikulam (58) and Umblachery (61) were genotyped. The wild type allele C was observed to be fixed in all the breeds except Kangayam cattle. The gene frequency of C and T alleles and genotype frequencies of CC, CT and TT were estimated in Kangayam breed of cattle and chi-square test revealed the population in Hardy- Weinberg disequilibrium at CYTB locus. Phylogenetic analysis showed that the indigenous cattle breeds were present under the same genetic ancestry of Bos indicus reference genome, while the Bos taurus reference genome diverged separately. From this study, the possibilities of selective sweep or population expansion after a recent bottleneck among the indigenous cattle breeds of Tamil Nadu could be concluded.

Topology Optimization and Multiobjective Optimization for Drive Axle Housing of a Rear Axle Drive Truck.

As one of the important load-bearing components of a truck, the drive axle housing must meet the requirements of stiffness and strength. The traditional design method uses redundancy design to meet the performance requirements. The joint design between the three-dimensional mathematical model and finite element model is adopted, and the optimal design of the drive axle housing is realized based on topology optimization and multiobjective optimization. Firstly, the static analysis of the drive axle housing of a rear axle drive truck was carried out with four typical working conditions. It was concluded that the four working conditions all operate under the yield limit of the material, and it was found that the maximum equivalent stress of the four working conditions occurs at the step of the half-shaft casing. Among the four working conditions, the most critical one is the maximum vertical force working condition. Then, based on the maximum vertical force working condition, the fatigue life analysis is conducted, and the minimum fatigue life appears at the transition position of the half-shaft sleeve and the arc transition position of the main reducer chamber. The remaining parts can meet the design requirements. The overall safety factor of the drive axle housing is mainly between 1 and 5 when operating under this working condition. Then, through modal analysis, the first to sixth natural frequency and vibration modes of the drive axle housing are extracted. Based on the modal analysis, the dynamic characteristics of the drive axle housing are further studied by harmonic response analysis and random vibration analysis. Finally, two kinds of lightweight optimization schemes for the drive axle housing are given. Topology optimization reduces the mass of the drive axle housing by 17.4%, but the overall performance slightly decreases. Then, the five dimensional parameters of the drive axle housing are selected as design variables. The mass, maximum deformation, equivalent stress, service life, and the first-, second- and third-order natural frequencies are defined as objective functions. Through the optimal space-filling design method, the experimental designs are performed and the sample points are obtained. Based on the results of experiment design, the multiobjective genetic algorithm and response surface method are combined to optimize the objective functions. The analysis results show that the mass is reduced by 4.35%, the equivalent stress is reduced by 21.05%, the minimum life is increased by 72.28%, and the first-, second-, and third-order natural frequency are also increased to varying degrees. Two different optimization strategies are provided for the design of the drive axle housing.

Study on the influence of thermo-physical parameters of phase change material panel on the indoor thermal environment of passive solar buildings in Tibet

In this study, an unsteady heat transport numerical model of phase change material (PCM) panel under indoor-outdoor dual thermal disturbance conditions was development by using the apparent heat capacity method, which was employed to evaluate the effect of thermal performance parameters of PCM on the heat storage and temperature regulation capability of PCM panel. Then, a single-space passive solar building located in Tibet was used as a basic building model to study the influence of thermo-physical parameters, such as phase change temperature, thickness and position of PCM panel in composite wall on indoor thermal environment. Meanwhile, the indoor discomfort degree hours and heating energy consumption of the passive solar building with composite wall containing PCM panel were quantitatively analyzed, and the dynamic payback period of PCM investment in Tibet was calculated for economic analysis. The results indicated that the phase transition temperature, thickness and position of PCM panel have a significant impact on its heat storage and temperature regulation capability, and the composite wall containing PCM panel with reasonable thermo-physical parameters could obviously damp indoor air temperature fluctuation and save the building heating energy consumption. Compared with the basic building, applying a 30 mm thickness PCM panel with phase transition temperature of 18 °C on the interior side of the composite wall could reduce indoor discomfort degree hours in studied period (Dec. 20 to Dec. 24) by 74.9% and reduce heating energy consumption in the whole heating period (Dec. 01 to Mar. 01) by 20.76%, respectively. Furthermore, the economic analysis results show that the application of PCM panels in passive solar buildings in Tibet has high economic value, and the dynamic payback period of PCM investment in Tibet with 3% discount rate is 41.29 years, which is lower than the usual service life of a building.

Demonstration of Escherichia coli Inactivation in Sterile Physiological Saline under High Pressure (HP) Phase Transition Conditions and Analysis of Probable Contribution of HP Metastable Positions Using Model Solutions and Apple Juice.

It was demonstrated that the inactivation of high pressure (HP) treatment on Escherichia coli survival in sterile physiological saline (SPS) was influenced by the treatment conditions: unfrozen, frozen-thawed and fully frozen (phase transition). In order to probe the enhanced phase transition microbial destruction, vibration effects of phase transition position were created and discussed. Test samples were placed in HP chamber for treatment (150/240/330 MPa, no holding time) at room temperature and a special cooling device was used to maintain the phase transition conditions. Results showed that the phase transition from ice I to ice III of frozen SPS could be realized based on the cooling of a 20% sodium chloride solution. HP treatment under fully frozen conditions produced the best lethal effect compared to unfrozen and freeze-thaw samples. Vibration tests were carried out by using model solutions and apple juice to explore the behavior of phase transition. A synchronous and advance phase transition of internal apple juice was realized, respectively, by using pure water and 5% sodium chloride solution as external vibration sources, and the advance phase transitions of external pure water were realized by using 5% sodium chloride solution and 5% glucose solution as internal vibration sources.

Heat-flow parameters affecting microstructure and mechanical properties of Al–Cu and Al–Ni alloys in directional solidification: an experimental comparative study

Abstract A comparative analysis was carried out of the alloys examined, using the results found for thermal variables, macrostructure, dendrite arm spacing, modulus of elasticity and microhardness. Comparing all the results for variables, a predominance was found of higher values for the Al-5.0 wt.% Cu alloy in relation to those for the Al-5.0 wt.% Ni alloy. Although structural transition has occurred in both alloys, the columnar–equiaxed transition position in castings was not altered during the solidification experiments. Addition of Ni solute into pure aluminum favors a significant decrease in tertiary dendrite spacing, while Cu addition leads to a coarser microstructure. Primary dendrite arm spacing, also, was measured along the castings of both alloys. Theoretical approaches such as the well-known Hunt–Lu, Bouchard–Kirkaldy, and Kurz–Fisher models were used to determine quantitatively this particular microstructural parameter. Good agreement was observed between experimental data and predictions by Hunt–Lu and Bouchard–Kirkaldy models, which assume solidification under a transient heat-flow condition. Finally, empirical equations relating tertiary dendritic arm spacing and mechanical properties to the scale of the dendritic microstructure have been proposed. While no relationship was observed between modulus of elasticity and tertiary dendritic arm spacing, addition of Cu into pure aluminum as an alloying element favored a reduction in the average value of modulus of elasticity when compared with those observed for the Al–Ni alloy. It was found that the microhardness decreases with increasing tertiary dendritic arm spacings. On the other hand, solute addition of Cu into commercially pure aluminum favors a microhardness higher than that verified during upward unidirectional solidification of the Al-5.0 wt.% Ni alloy.

A novel ANN-Based boundary strategy for modeling micro/nanopatterns on airfoil with improved aerodynamic performances

In this paper, in order to overcome computational challenge in numerical simulations of airfoil covered with micro/nanopatterns for aerodynamic drag-reduction design, an ANN-Based boundary strategy is proposed to balance the accuracy and efficiency. Lattice Boltzmann Method (LBM) is utilized to extract the micro/nanoflow characteristics in the near-wall region considering the rarefied effect and the available microscopic data is used to train the surrogate boundary model by Generalized Regression Neural Network (GRNN). The modified boundary conditions obtained by ANN-Based model replacing the real complex and fine micro/nano structure are applied on the smooth configuration to perform macroscopic simulations. Rectangular riblets as micro/nano pattern are discussed for our study. Various arrangement strategies of rectangular riblets over airfoil are adopted by adjusting the width, height, and coverage area to investigate their effects on aerodynamic performances. The results indicate that for the riblet airfoil, the skin friction reduces and the transition position moves backward compared with those of the smooth airfoil. Furthermore, the lift-to-drag ratio also significantly increases and the rate of improvement is up to 13.8% at the Angle of Attack (AOA) of 1°. This paper shows a perspective in aerodynamic design with micro/nano pattern for drag reduction by providing an innovative multi-scale simplified simulation strategy.

Experimental study on the evolution of mode waves in laminar boundary layer on a large-scale flat plate

In this research, to study the hypersonic boundary-layer transition, experiments were conducted on a large-scale flat plate with a length of 3.2 m at a zero angle of attack in the hypersonic shock tunnel duplicating flight conditions. Surface-mounted piezoelectric pressure sensors and coaxial thermocouples were, respectively, used to measure the pressure fluctuations and wall heat transfer. The spatial distribution of heat transfer was used to distinguish the transition. Under the test conditions of Ma = 7.0, T0 = 2120 K, and Re∞ = 6.08 × 105 m−1, no transition occurred, and under the test conditions of Ma = 7.0, T0 = 2220 K, and Re∞ = 1.23 × 106 m−1, the transition position was s = 2.06 m. The repeatability of the experiment was found to be good. Furthermore, focus was placed on the spectral and spatial/temporal evolution characteristics of pressure fluctuations in the laminar boundary layer. The experiment captured the three frequency distributions of mode waves in the laminar flow zone. Among the mode waves distributed in the three frequency bands, the low-/high-frequency bands were dominant, and the mid-frequency band exhibited a staged contribution. The amplitude energy percentages of the high- and low-frequency mode waves exhibited opposite trends in both time and space, which means that the disturbance energy will be distributed among the various harmonics in the laminar stage.

A Comparative Study of the Buoyancy-Opposed Wall Jet using Different Turbulent Models

A comparative study of the buoyancy-opposed wall jet has been carried out using RANS methods (including RNG model, Realizable k-ε model, and two low Reynolds number k-ε models) and LES methods (including the subgrid scale model developed by Smagorinsky et al.(1963), Germano et al. (1991) and Kim et al. (1997)). The capability of each turbulence model to predict the flow field and temperature field in mixing stage was investigated. The results show that the k-ε series model can accurately predict the velocity distribution of flow field under isothermal case. However, in the case of buoyancy, due to the assumption of turbulent normal stress isotropy, the trend of temperature change in the mixing region and transition position existed an obvious deviation with experimental data. The LES methods, solved directly the large scale vortices, take into account the influence of turbulence stress anisotropy in the mixing region on the temperature change and capture the temperature change trend over the whole domain accurately. Due to the application of the subgrid kinetic energy transport equation, KET model has certain advantages in numerical simulation of similar engineering flow phenomenon.

Low-Reynolds-number airfoil design optimization using deep-learning-based tailored airfoil modes

Low-Reynolds-number high-lift airfoil design is critical to the performance of unmanned aerial vehicles (UAV). However, since laminar-to-turbulent transition dominates the aerodynamic performance of low-Reynolds-number airfoils and the transition position may exhibit an abrupt change even with a small geometric deformation, aerodynamic coefficient functions become discontinuous in this regime, which brings significant difficulties to the application of conventional aerodynamic design optimization methods. To efficiently perform low-Reynolds-number airfoil design, we present a tailored airfoil modal parameterization method, which reasonably defines the desired design space using deep-learning techniques. Coupled with surrogate-based optimization, the proposed method has shown to be effective and efficient in low-Reynolds-number high-lift airfoil design. It is found that it is necessary to consider laminar-to-turbulent transition and to perform multi-point optimization in practical low-Reynolds-number airfoil design. The maximal lift coefficient is an active constraint influencing the selection of the optimal cruise lift coefficient. The results show the complexity of low-Reynolds-number high-lift airfoil design and highlight the significance of the proposed method in the improvement of optimization efficiency.

Low magnetic-field induced high temperature dynamic magnetoelectric coupling performances in Z-type Sr3Co2Fe24O41

Magnetic-field induced dynamic magnetoelectric coupling effects and polarization performance of Z-type Sr3Co2Fe24O41 (SCFO) ceramic has been investigated. Results found that SCFO’s transverse tapered magnetic structure can induce electric polarization, and its electric polarization direction will not change under external magnetic effects. First-order dynamic magnetoelectric coupling coefficient (α) and second-order dynamic magnetoelectric coupling coefficient (β) of SCFO exhibited strong response main in magnetic structural phase transition region. The magnetoelectric structural phase transition position appeared in low magnetic field, and the magnetic moment vector and its corresponding electric polarization vector of SCFO exhibited the most unstable state near its equilibrium position, which is beneficial for inducing strong dynamic magnetoelectric coupling response. When the applied magnetic fields to SCFO increased, the magnetic moment stability near the equilibrium position increased, and the dynamic magnetoelectric coupling response decreased. Results showed that the dynamic magnetoelectric coupling response of SCFO can bear T 1 = 370 K high temperature. The dynamic magnetoelectric coupling response induced by low magnetic fields in SCFO contributes to its actual application in next generation magnetoelectric information storage devices.

Facilitating high pressure phase-transition research and kinetics studies at subzero temperatures using self-cooling laboratory units

Self-cooling phase-transition units were built and tested to successfully carryout pressure shift freezing, high pressure thawing and subzero temperature microbial destruction kinetics. The design of these equipment has been progressively improved over the years as highlighted in this paper. Phase transition data on grape & apple juices, and sodium chloride (20%) & glucose solutions (20%) in Ice I were gathered and modeled using Simon-like and polynomial equations. Factors influencing the Ice I and water to Ice III phase transition position were evaluated, and found to be mainly affected by the solute in the aqueous solution. For pressure shifting freezing and pressure assisting freezing to Ice III, water and 20% sodium chloride solution were successfully employed and verified as cooling media for creating the temperature change pathway of potato and carrot. Using sodium chloride solution (20%) as the cooling medium, the phase transition pathway of apple juice and grape juice under high pressure for the phase transition of Ice I and metastable water to Ice III was established. This could be used in kinetic studies. The developed cooling unit concepts can use in any commercial high pressure equipment for subzero temperature treatment of foods without externally supplied cooling.

Safety analysis of leakage in a nuclear hydrogen production system

Due to its unique advantages, such as clean and pollution-free, hydrogen energy has gradually improved its energy transition position. Constructing nuclear hydrogen production systems is a necessary means to achieve large-scale hydrogen production, and the study of hydrogen leakage and diffusion behavior is critical to commercializing hydrogen production systems. In engineering practice, the distance between the hydrogen storage device and the nuclear power plant is an important indicator to measure the safety of nuclear hydrogen production. To study the influence of gas storage tank's own conditions and external environmental conditions on leakage diffusion, influencing factors such as wind speed, leakage direction, leakage diameter, leakage height, and leakage angle are discussed in the present study. By calculating severe working conditions combined with the above multiple factors, the longest distance of hydrogen diffusion is determined. Finally, peak overpressure impact generated by hydrogen explosion was evaluated, and the minimum separation distance required to avoid safety risks was predicted. The results demonstrate that when the wind direction is consistent with the leakage direction, and the leakage angle is 0°, the higher the wind speed, the larger the leakage diameter and the lower the leakage height, resulting in a longer diffusion distance. Under more extreme and severe working conditions, the diffusion distance of combustible hydrogen cloud can reach as far as 237 m. Once hydrogen diffusion explodes, the minimum separation distance required is about 338 m. This research provides an effective method for safety risk assessment of a nuclear hydrogen production system.

Vortex structures evolution in supersonic mixing layers with different inlet Reynolds numbers based on the Lagrangian method

The supersonic mixing layer is a typical flow structure in an aircraft’s optical seeker. The free incoming flow and cooling jet form a mixing layer through shearing. In most cases, the flow has become a fully developed turbulent due to complex factors during flight. This paper mainly focuses on the influence of the inlet Reynolds number on the development of the supersonic mixing layer. The rescaling/recycle method is used to generate turbulence at the inlet of the mixing layer. The results show that when the turbulence of the high-speed flow is strong, the transition position of the mixing layer will be advanced and the mixedness will be enhanced. The mixing efficiency is high at the position corresponding to the vortex in the mixing layer. Finally, the Lagrangian coherent structure and particle tracking methods are used to analyze different mixing processes, and the entrainment characteristics of the vortex are studied.

Remote Sensing Monitoring of Rice Fields: Towards Assessing Water Saving Irrigation Management Practices

Rice cultivation is one of the largest users of the world’s freshwater resources. The contribution of remote sensing observations for identifying the conditions under which rice is cultivated, particularly throughout the growing season, can be instrumental for water, and crop management. Data from different remote sensing platforms are being used in agriculture, namely to detecting anomalies in crops. This is attempted by calculating vegetation indices (VI) that are based on different vegetation reflectance bands, especially those that rely on the Red, Green, and near-infrared bands, such as the Normalised Difference Vegetation Index (NDVI) or the Green Normalised Difference Vegetation Index (GNDVI). However, particular features of different crops and growing conditions justify that some indices are more adequate than others on a case-to-case basis, according to the different vegetation’s spectral signatures. In recent years, a vegetation index related to the Red Edge reflectance band, the Normalised Difference Red Edge (NDRE) has shown potential to be used as a tool to support agricultural management practices; this edge band, by taking a transition position, is very sensitive to changes in vegetation properties. This work, focusing on the rice crop and the application of different irrigation practices, explores the capability of several VIs calculated from different reflectance bands to detect variability, at the plot scale, in rice cultivation in the Lower Mondego region (Portugal). The remote sensing data were obtained from satellite Sentinel-2A imagery and using a multispectral camera mounted on an Unmanned Aerial System (UAS). By comparing several vegetation indices, we found that NDRE is particularly useful for identifying non-homogeneities in irrigation and crop growth in rice fields. Since few satellite sensors are sensible in the Red Edge band and none has the spatial resolution offered by UAS, this study explores the potential of UAS to be used as a useful support information tool in rice farming and precision agriculture, regarding irrigation, and agronomic management.

Techniques for Turbulence Tripping of Boundary Layers in RANS Simulations

The exact placement of the laminar–turbulent transition has a significant effect on relevant characteristics of the boundary layer and aerodynamics, such as drag, heat transfer and flow separation on e.g. wings and turbine blades. Tripping, which fixes the transition position, has been a valuable aid to wind-tunnel testing during the past 70 years, because it makes the transition independent of the local condition of the free-stream. Tripping helps to obey flow similarity for scaled models and serves as a passive control mechanism. Fundamental fluid-mechanics studies and many engineering developments are based on tripped cases. Therefore, it is essential for computational fluid dynamics (CFD) simulations to replicate the same forced transition, in spite of the advanced improvements in transition modelling. In the last decade, both direct numerical simulation (DNS) and large-eddy simulations (LES) include tripping methods in an effort to avoid the need for modeling the complex mechanisms associated with the natural transition process, which we would like to bring over to Reynolds-averaged Navier–Stokes (RANS) turbulence models. This paper investigates the implementation and performance of such a technique in RANS and specifically in the k-omega SST model. This study assesses RANS tripping with three alternatives: First, a recent approach of turbulence generation, denoted as turbulence-injection method (kI), is evaluated and investigated through different test cases; second, a predefined transition point is used in a traditional transition model (denoted as IM method); and third a novel formulation combining the two previous methods is proposed, denoted gamma -kI. The model is compared with DNS, LES and experimental data in a variety of test cases ranging from a turbulent boundary layer on a flat plate to the three-dimensional (3D) flow over a wing section. The desired tripping is achieved at the target location and the simulation results compare very well with the reference results. With the application of the novel model, the challenging transition region can be excluded from a simulation, and consequently more reliable results can be provided.

Design of a centrifugal acceleration system for high velocity injection of impurity pellet into EAST tokamak

A centrifugal pellet injection system for high velocity impurity pellet injection to control ELMs and research impurity transport has been developed for the Experimental Advanced Superconducting Tokamak (EAST). The system is composed of the dropper, the centrifugal accelerator, vacuum pumping system and the diagnostic unit. The centrifugal accelerator is designed to accelerate the pellet by the rotating arm driven by a KYKY F100 turbomolecular pump with an adjusted rotating velocity from 0 to 42,300 rpm. In order to evaluate the stability of the rotating arm, the stress distribution of the rotating arm at different rotating velocities is analyzed by the stress field simulation, and the result shows the maximum stress of the rotating arm appears at the transition position between the large circular groove and the acceleration groove. By simulation analysis, it is noted that the arm can work steadily at 2500 rad/s (corresponding to about 398 Hz arm rotation frequency) rotating velocity and may be broken at 4000 rad/s (637 Hz). By the bench testing using the Li pellets of 1 mm diameter as injection material, it shows the centrifugal accelerator can work steadily for a long time under the condition that the rotating velocity doesn't exceed 2200 rad/s (350 Hz) and the maximum velocity of the pellet can reach 286 m/s. Based on the results of simulation and bench test, the centrifugal pellet injection system was installed and then injected Li pellets into the plasma steadily and continuously with the rotating velocity <2200 rad/s on EAST.

Tribological behavior of short carbon fiber reinforced polyetherimide composite under water lubrication conditions

Short-carbon-fiber-reinforced polyetherimide (SCF/PEI) composites have good mechanical properties and are expected to have wide applications including components serving under water lubrication conditions. However, no work has been reported on the tribological behaviors of SCF/PEI composites under water lubrication conditions. This work attempts to explore the practicality of the SCF/PEI composite from a tribological point of view under water lubrication conditions. SCFs are coated by polydopamine (PDA) to enhance the interfacial interaction between fibers and matrix. The tribological performances of SCF/PEI composite are systematically investigated by sliding wear tests under tap and sea water lubrication conditions. Experimental results show that the SCF/PEI composite has a better friction performance in water lubrications than that under dry sliding because of the separation effects formed by a water molecule film and a transfer film. However, no remarkable differences of wear resistance are found between water lubrication and dry contact conditions, and the magnitude of specific wear rate under these conditions is around 1 × 10−6 mm3/N·m. It is found that contact surface hardness of the SCF/PEI composite is reduced after a sliding test in water due to the plasticization phenomenon, especially sea water can accelerate the diffusion of water molecules into matrix, making the specific wear rate in sea water is ten times of that in tap water for highly-loaded conditions. Meanwhile, the abrasive wear is observed to be the dominated wear mode in boundary lubrication regime, and the adhesion wear occurs around the transition position from the boundary to mixed lubrication regime. It is also found that pressure has a significant effect on the temperature rise within the contact surface than the speed does. Finally, the tribological performance of the SCF/PEI composite under water is exhibited to be better than that of most of polymers and composites reported previously.

EVALUATION OF THE TEACHING TECHNIQUES OF THE PIANO ARRANGEMENT OF AL YEMENI MOR YEMENI SONG

In this study, AI Yemeni Mor Yemeni piece is mid-level piano arrangement is aimed to evaluate the teaching stages of the students in line with the opinions of field experts. The research was analyzed using descriptive analysis and interview method which is one of the qualitative research methods. The appropriateness of the piece was asked to 10 field experts by a semi-structured interview form. The evaluation of the work by field experts in terms of piano teaching techniques according to the piano arrangement has been examined under three sub-titles; the basic information used in the arrangement, the technical equipment used in the arrangement and the interpretation of the work. Within the scope of basic information, number of measures, time repeats, dal segno, D.S.al Fine, octave sign, tie, modifier signs; within the scope of technical expression, pedal, arpeggio, tie and slur, chord transition, closed and open position transition; within the scope of the interpretation of the work, the concepts of nuance and pedal were examined. The findings were analyzed by describing them in accordance with the feedback given by the field experts. As a result, the research was concluded that the arrangement of Al Yemeni Mor Yemeni is appropriate for an individual who plays the piano at an intermediate level. In this direction, the suggestions of the experts in the field were evaluated.&#x0D; Keywords: Cyprus folk song, piano arrangement, piano teaching techniques.