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The purpose of this study is to analyze the rotational speed characteristics of a spherical turbine start-up process, and the rotational speed characteristic of the spherical turbine is studied by numerical simulation. In order to ensure the reliability of the numerical simulation, the numerical simulation results at different flow rates are compared with the experimental results, and the results show that it is feasible to investigate the rotational speed characteristics of the spherical turbine using numerical simulation. The numerical results demonstrate that the start-up process of the spherical turbine can be separated into two stages: the start-up acceleration stage and the transition stage, which are followed by periodic fluctuations of the rotational speed. In addition, when the flow rate is 8 m3/h , the spherical turbine can self-start under the load coefficient (Bg) if less than 3×10−5. If the Bg is larger than 3×10−5 , the turbine fails to start-up. The failed start-up shares characteristics: the turbine only moves forward and backward alternately in a small angular range. However, eventually, the applied load torque dominates, and the turbine starts to reverse. It is found that the flow rate and the turbine rotational speed present a linear relationship under the no-load operating condition. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Enhancing fatigue life of thick-walled cylinders used for high-pressure application is an important design task. Cylindrical vessels find applications in oil and gas industries, food and chemical industries, nuclear reactors and gun barrels. They are susceptible to cracking due to high tensile stress caused by internal pressurization at their inner side during operation. Compressive residual stress can potentially help in suppressing inner cracks in such components to safeguard against any awkward situations. In this work, a hybrid rotational-swage autofrettage method is proposed to induce beneficial compressive residual stresses at the interior wall of a thick-walled cylinder. An analytical model is developed to determine the residual stresses in the process using Tresca yield criterion and its associated flow rule for non-hardening material behavior. The compressive residual stress generated in the hybrid autofrettage process is assessed for increase in the fatigue life of pressurized cylinders. To exemplify the process, cylinders of two different materials, viz. SS316 and Al7075-T6, are considered to be rotated while interfering at their inner side with an axially driven oversized AISI4340 mandrel. The design speeds of the cylinders for each material are obtained as a function of the swaging mandrel interference without contact separation during the process. The residual stresses in the cylinders are evaluated numerically, and the performance of the cylinders on enhancing the fatigue life under in-service internal pressurization is investigated using Paris law. [ABSTRACT FROM AUTHOR]

In this paper, we conduct a comprehensive numerical investigation of a ducted wind turbine under various rotational speeds, focusing on aspects such as boundary layer thickness and momentum thickness. Our study utilizes advanced computational fluid dynamics techniques to assess the intricate flow characteristics and aerodynamics of the ducted wind turbine, providing a detailed understanding of its operation under different speed conditions. The primary objectives are to comprehend the effect of the wind turbine's rotational speed on the boundary layer thickness and the momentum thickness, two crucial parameters influencing the turbine's performance and efficiency. Our findings reveal a significant correlation between the increase in rotational speed and the growth of flow separation, a phenomenon typically indicated by an expansion in the area of negative wall shear stress. This research contributes valuable insights into the behavior of ducted wind turbines at varying rotational speeds, and the acquired knowledge could potentially be utilized in designing and improving wind turbine systems to achieve better performance and enhanced operational efficiency. [ABSTRACT FROM AUTHOR]

This study investigated the impact of a cylindrical obstacle on convection in an inclined square cavity filled with water-Al2O3 nanofluid. Using the finite volume method, the problem was resolved by having the inner cylinder rotate adiabatically while other walls were thermally insulated. Additionally, the bottom wall was hotter than the top. The study examined the effects of cylindrical obstacle radius (0.1 ≤ R ≤ 0.2), rotation speed (-500 ≤ Ω ≤ 500), Richardson number (0.01 ≤ Ri ≤ 100), volumetric nanoparticle fraction (0.02), and Grashof number (Gr = 104) on heat transfer rate or Nusselt number. The results were compared with previous literature, and the influence of the cylindrical obstacle rotational speed on convection flow was evaluated. An increase in the counterclockwise angular rotating speed resulted in higher nanofluid flux. The heat transmission coefficient increased as the Richardson number decreased. The use of nanofluid in the enclosure increased the coefficient of heat flow through mixed convection. Finally, the study showed that the convection heat exchange is enhanced with the increase in the radius. Moreover, an enhancement of the Nusselt number around 46% was reported for the cylinder, under Gr=10000, Φ=0.02, γ=45° and Ri= 10. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated the impact of a cylindrical obstacle on convection in an inclined square cavity filled with water-Al2O3 nanofluid. Using the finite volume method, the problem was resolved by having the inner cylinder rotate adiabatically while other walls were thermally insulated. Additionally, the bottom wall was hotter than the top. The study examined the effects of cylindrical obstacle radius (0.1 ≤ R ≤ 0.2), rotation speed (-500 ≤ Ω ≤ 500), Richardson number (0.01 ≤ Ri ≤ 100), volumetric nanoparticle fraction (0.02), and Grashof number (Gr = 104 ) on heat transfer rate or Nusselt number. The results were compared with previous literature, and the influence of the cylindrical obstacle rotational speed on convection flow was evaluated. An increase in the counterclockwise angular rotating speed resulted in higher nanofluid flux. The heat transmission coefficient increased as the Richardson number decreased. The use of nanofluid in the enclosure increased the coefficient of heat flow through mixed convection. Finally, the study showed that the convection heat exchange is enhanced with the increase in the radius. Moreover, an enhancement of the Nusselt number around 46% was reported for the cylinder, under Gr=10000, ∅=0.02, =45° and Ri= 10.

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Additive friction stir deposition (AFSD) is a solid state coating process as well as a developing solid state additive manufacturing technology. AFSD has numerous advantages over friction surfacing coating technology. However, extensive research has demonstrated that a relationship between microstructure and mechanical properties exists at present. On the other hand, a few research focus on temperature field evolution.The temperature field during AFSD is examined in this paper using a combined experimental-numerical approach. According to characterizations of AFSD thermal process, AFSD was classified into friction preheating stages and steady deposition stages. The friction preheating model and the steady deposition heat model are both established. The experiment is carried out to confirm the temperature difference between the simulation and the experiment, where experimental and numerical results correspond well. The AFSD process parameters include rotational speed, feed speed, and deposition rate. The purpose of this research is to examine the effect of process parameters on heat input during the production of aluminum alloy coating by AFSD. The results shows that rotational speed is a critical element that influences heat input. Overall, the comparisons of experimental and numerical results show that the numerical model's accuracy is satisfactory, and the effect of process parameters on heat input was thoroughly investigated. [ABSTRACT FROM AUTHOR]

Introduction: Rotary nickel–titanium files are subjected to shear and flexural stresses during instrumentation. Increasing the rotational speed may reduce the shear stresses but can deteriorate the fatigue life of the file. This in vitro study aimed to address the influence of three rotational speeds 300, 500, and 700 RPM on the apical force and torque generated during instrumentation as well as on file fracture. Materials and Methods: A total of 48 simulated canals were divided into three groups: 300, 500, and 700 RPM (n = 16). Each canal was instrumented using a ProTaper Next XA orifice opener to prepare the coronal third and an X2 shaper to prepare the middle and apical thirds. A new set of files (XA and X2) was used to prepare four canals. A customized setup was used to evaluate the maximum apical force and torque corresponding to each third of the canal. The files were inspected for deformation or fracture using a stereomicroscope. Force and torque data were analyzed using analysis of variance and Post hoc Tukey test at 5% significance. Results: Five hundred and 700 RPM generated a significantly lower apical force and torque than 300 RPM at all canal thirds (P < 0.001). However, 700 RPM was superior to 500 RPM at the coronal third only (P < 0.001). No incidence of deformation or fracture was reported in any group. Conclusions: In resin artificial canals, increasing the rotational speed of the tested ProTaper Next files resulted in significantly less apical force and torque without increasing the incidence of fracture. Further studies involving natural teeth are required to validate these results using natural teeth. [ABSTRACT FROM AUTHOR]

The utilization of aluminium alloy composite materials is increased progressively in automotive, aerospace, and sports allocations due to their distinct physical and mechanical properties. The conventional metal joining process is not suitable for joining the composite material. The present work of silicon carbide (SiC) compacted aluminium alloy (AA6061) composite surface is joined by friction stir welding (FSW) process under the rotational speed of 800, 1200, and 1600 rpm. Influences of tool rotational speed on welding interface quality mechanical and fatigue properties of AA6061/SiC composite surface are evaluated. The internal defect area of the weld joint is detected by radiograph inspection, and its surface morphology is analyzed through the Scanning Electron Microscope (SEM) apparatus. It revealed that the coarse aggregated inter-metallic structure with an effective interface of weldment was observed. The 1200 rpm (rotational speed) performed AA6061 composite found enhanced yield and tensile strength of 23.7% and 25.66% improvement compared to the yield and tensile strength of weldment operated under 800 rpm rotational speed. The hardness of composite weldment is increased significantly with increased tool rotational speed. The maximum hardness of 88HV is by 1200 rpm performed weld joint. Sample 3 performed higher fatigue life (1.8 × 106 cycles) without failure. [ABSTRACT FROM AUTHOR]

Copyright of Misr Journal of Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The adoption of additive manufacturing (AM) to complement conventional manufacturing to produce industrial components has been widely accepted. This is critical to the fabrication of designs with high complexity, which traditional manufacturing cannot match. In this regard, a commercial Pelton turbine with a traditional design was improved using both reverse engineering and hydro-dynamic finite element method simulations to produce a new design. Then, the performance of our new design is experimentally evaluated in terms of its rotational speed. In our new design, using the Design for AM (DfAM), several drawbacks of the traditional Pelton turbine design (e.g., improper welding and alignment and blunt splitters that lead to a heeling effect) were overcome by the following steps: (i) employing computational fluid dynamics analysis, (ii) consequently, extracting key geometrical characteristics from the original design, such as the number of buckets, runner wheel diameter, and bucket width, and length (iii) finally, referencing other design parameters using generally known empirical data. DfAM techniques were applied to reduce the post-processing requirements of additively manufactured turbine buckets, considering minimum feature size and avoidance of support structures on water-contacted surfaces, as well as simple and manual support removal. The new design in this study exhibits high rotational speeds ranging from 8.2 to 32.73% at an inlet pressure of 5 MPa and different nozzle angles. [ABSTRACT FROM AUTHOR]

In this study, the friction stir spot welding (FSSW) process for the magnesium alloy (AZ91) sheet materials are investigated. Friction stir spot welding (FSSW) is a solidstate welding process and one of the innovative methods to join specifically automotive components. Recently magnesium alloys are promising materials where combination of high strength and low density can be observed to improve vehicle performance and reduce emissions and fuel consumption in structural materials for automotive applications. A finite element model (FEM) established to understand the effect of axial force and rotational speed during the simulation in automotive applications. The FEM investigates the effect of axial force ranging from 1 kN to 8 kN and rotational speeds of 1000 rpm - 4000 rpm. The model analyses the heat flux and the temperature rise that leads defect formation after the process. 4.5 kN, 6 kN and 8 kN axial forces and 3000 rpm- 4000 rpm rotational speeds are evaluated as the critical values in terms of defect and crack formation during the process under specified boundary conditions. Finally, several non-destructive inspection methods are suggested to secure structural integrity after the FSSW process to eliminate the harmful effects of surface and volumetric discontinuities. [ABSTRACT FROM AUTHOR]

Today, wooden products are widely spread in the industry of furniture, art boards, wooden dishes, etc. The traditional and manual manufacturing methods of producing these artefacts cannot compete with mechanized production methods, especially computer numerical control (CNC) machines. Therefore, using of these devices is always increasing. Nevertheless, one of the parameters that affect the production speed is the surface roughness, and the workshops have to spend a lot of time on polishing the products. For this reason, in the present research, the effect of machine parameters (feed speed, rotational speed and transverse step) and tool characteristics (diameter, number of cutting edge and type of cutting edge) on surface roughness of beech wood has been investigated. The outcomes demonstrated that cutting tools with two spiral cutting edges have a more favorable surface roughness than cutting tools with a straight cutting edge and one spiral cutting edge, and tools with a straight edge are not suitable for beech wood. It was also observed that by reducing the transverse step from 0.7D to 0.3D, a lower surface roughness is created. By reducing the tool diameter from 6 to 4 and 3 (mm), reducing the feed speed from 60 to 20 (mm/min) and increasing the rotational speed from 15000 to 25000 (rpm), the surface roughness of final product was improved, significantly. [ABSTRACT FROM AUTHOR]

A novel method, friction stir spot welding using a consumable sheet (FSSW-C), is introduced here with the aim of joining dissimilar sheets. In this process, faying surfaces of the base materials are kept at a specific gap, and a consumable sheet is placed on the top of the base materials. When the tool progresses into the consumable sheet, the plasticized consumable material gets extruded into the gap and joining occurs between the base materials. The tool never touches the steel base material overcoming the tool wear problem. In the present work, AA6063-T6 and CRCA/IS-513 are the base sheets, and AA6063-T6 is the consumable sheet. The effect of tool rotational speed on the joint formation, interface characteristics, microhardness, temperature evolution, lap shear strength, bend shear strength, and fracture modes have been analyzed. Microstructural zones are also revealed. The rotational speed of 900 rpm is the best choice for FSSW-C of AA6063-T6 and CRCA/IS-513 sheets, keeping 2-mm/min plunge speed, 2-mm plunge depth, 5-s dwell time, and 1.5-mm gap constant. However, additional case studies reveal a plunge depth of 1.5 mm (at 900 rpm) as a better choice due to further lap shear fracture load improvement. [ABSTRACT FROM AUTHOR]

In order to solve the problem of the low qualification rate of the pilling and coating of small-grain forage seeds, a vibration force field is introduced to the traditional vertical disk coating machine to promote the mixing of materials and improve the qualification rate of the pilling. Using the typical small-grain forage seed red clover as an example, we used the vibration force field after adding seed powder particles to a coating pot for the theoretical analysis of the force situation, using the discrete element software EDEM to construct a red clover seed simulation model with the coefficient of discretization as the evaluation index. We studied the effects of the rotational speed of the coating pot, the vibration frequency of the pot, the amplitude of the vibration of the pot, and the other operating parameters of the pot on the uniformity of the seed powder mixing, with the pelletization of the pass rate as the physical evaluation standard, using a one-way test to study the effect of operating parameters on the pelletization pass rate. We used the qualified rate as the physical evaluation standard, through a single-factor test, to study the influence of the working parameters on the qualification rate of the pilling. The results show that the simulation test evaluation index of the discrete coefficient and the physical test evaluation index of the pilling qualification rate with the change rule of the working parameters is consistent with the discrete coefficient, and can be used as an indirect evaluation index of the quality of pilling. To further determine the optimal combination of working parameters, a quadratic regression orthogonal design test was conducted with the discrete coefficients as the evaluation index, and the second-order regression equations of the red clover seeds were established and analyzed by ANOVA using Design-Expert software. The study shows that, when the rotational speed of the coating pot is 307.204 rpm, the vibration frequency is 2.526 Hz, and the vibration amplitude of the coating pot is 5.843 mm, the predicted coefficient of dispersion at this time is 8.1%. Simulation using the best combination of parameters to obtain the average value of the dispersion coefficient of 8.4%, relative to the predicted value of 3.7%, indicated that the optimization of the experimental regression model is accurate, and the results obtained for the vibration of small seeds under the conditions of the design of the pellet granulation coating machine and the optimization of the pelletization coating process parameters have a certain degree of reference significance. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present work investigates the effect of rotational speed on joint quality during Friction Stir Spot Welding (FSSW) using a consumable pin, where a consumable pin is used with a rigid tool shoulder for welding AA6061-T6 sheets to produce an exit-hole-free FSSW joint. Joint quality was analysed using lap shear test, macrostructure, microstructure and microhardness analysis at five rotational speeds, viz. 360, 462, 557, 900 and 1200 revolutions per minute (RPM). The joint strength increased with increase in rotational speed from 360 RPM to 900 RPM and then decreased with further increase in rotational speed. A 1.7 times increase in joint strength was observed for FSSW at 900 RPM with reference to 360 RPM. As expected, both energy input and temperature increased with rotational speed. The energy input increased by only 27.5% as the rotational speed was increased from 360 to 900 RPM. Finite element (FE) simulations were conducted for validation and study using commercial FE software, DEFORM-3D, to predict temperature distribution, force, torque and material flow. Lap shear test simulations matched with experimental results within reasonable (∼7%) accuracy except for very low rotation cases. However, failure load provided better matching with experimental results when Cockcroft-Latham damage model was used instead of Freudenthal damage model. [ABSTRACT FROM AUTHOR]

In this study, aluminum 6061-T6 plates were joined with low-carbon galvanized steel using friction stir spot welding. Three conical pins with varying lengths (short, medium, and long) were utilized, along with different dwell times and rotation speeds of the tool. The objective of this research was to compare the simultaneous effects of several important process parameters on mechanical and welding properties. The results indicate that the use of short conical pins significantly increased the microhardness in the upper aluminum plate. Conversely, increasing the pin length led to higher microhardness in the lower steel plate. Tensile shear loading was greater for short pins compared to medium pins, attributed to the influence of the tool shoulder. However, with increasing pin length, failure loading reached its highest value due to the dispersion of particles in the weld. The failure mode for short pins exhibited a mixed pattern, which transitioned to a ductile shape in all conditions as pin length increased. Overall, the most influential parameter was the tool penetration depth, which positively affected the obtained properties. The rotational speed of the tool was the second most significant parameter, followed by the dwell time.

The present work aims to develop a computational procedure for investigating the vibration behaviour of pre-twisted laminated composite shell containing graphene inclusions in their matrix. According to nanoscopic empirical equations, graphene's mechanical properties are determined by its size dependence. It has been demonstrated that the orthotropic mechanical properties of composite laminates made from carbon fibres and hybrid matrix can be evaluated. Based on pre-twist and geometric configurations, finite element methods have been used to model hybrid materials shells that include carbon fibre, graphene, and graphene-fibre reinforcement. As part of the validation process, the proposed method is compared with other methods when possible. Finally, the vibrational behaviour of the composite shell is extracted by imposing a twisted angle on a cantilever boundary condition. An analysis of vibrations for each configuration is presented in this paper, as well as the effects of graphene inclusions on natural frequencies. As graphene volume fractions in the matrix increase, the natural frequencies of every mode also increase. When the hub radius and rotational speed are increased, the frequency parameter increases with an increase in graphene volume in the hybrid polymer composite pre-twisted shell.

Understanding the fatigue behaviors of weld joints is significant in engineering practice. Rotary friction welding (RFW) can join the additively manufactured polymer components. Until now, no research has focused on the fatigue behavior of polymer components jointed via RFW. This study investigates the fatigue life of ABS/PC dissimilar components fabricated via RFW and proposes the fatigue mechanism based on the failure structure. This work uses five different cyclic loads and rotational speeds to investigate the fatigue life. The fatigue life of the RFW of ABS/PC dissimilar rods is better compared with the pure ABS and pure PC specimens due to weld and integrity microstructural changes resulting from the combination of ABS and PC materials. The number of cycles until the rupture of RFW of ABS/PC dissimilar components (y) can be determined by the cyclic load (x) according to the prediction equation of y = −838.25x2 − 2035.8x + 67,262. The fatigue life of the RFW of ABS/PC dissimilar components increase with the increased rotational speed. The number of cycles until rupture (y) can be determined by the different rotational speeds (x) according to the prediction equation of y = 315.21x2 + 2710.4x + 32,124. [ABSTRACT FROM AUTHOR]

Methods for graphical representation of the connection between the initial data and the main results of the design of worm gears are considered. Graphs have been developed that visualize the initial data, the resulting dimensions, and the sliding speeds in a wide range of gear ratios. Working with summary graphs prevents errors and significantly reduces the time for selecting transmission parameters in accordance with the performance criteria. [ABSTRACT FROM AUTHOR]

Oleophilic skimming is a primary alternative when addressing oil spill accidents. However, the existing literature does not define accurately the optimum design and operating conditions of the oleophilic skimmer. In this research, an extensive CFD investigation was conducted on the performance of the drum skimmer. Seven parameters were tested, namely drum diameter, drum centre height, oil slick thickness, rotational speed, oil density, oil viscosity and oil surface tension. The simulations were performed by applying the volume of fluid technique using the OpenFOAM package. The two-dimensional numerical setup was tested for grid size, domain extension and time-step convergence, and the results were validated with experimental data from the literature. The skimmer performance was evaluated through the oil recovery rate and water ingestion rate. The study illustrated that the oleophilic drum skimmer best functions at rotational speed within 30–60 rpm, drum diameter within 200–300 mm, drum centre-height-to-diameter ratio within 0.3–0.4, oil slick thickness ≥ 15 mm and oil viscosity within 10–100 cSt. [ABSTRACT FROM AUTHOR]

This study investigates the impact of different control strategies on the performance of a single desiccant wheel dehumidifier with a heat recovery in real-world applications. A method to minimize the performance fluctuation as an effect of dynamic system performance response is proposed. First, the effect of regeneration heat input (Qin) changes on the system performance of the above dehumidifier was clarified. Second, the performance behavior was examined in response to transient conditions for different operation modes and was used to determine the most effective operation mode. Qin was assumed to change over time, which would influence the regeneration temperature and airflow velocity. The results showed that fluctuating Qin reduces the dehumidification capacity (ΔX) and coefficient of regeneration performance (COPreg). Therefore, a rotational control speed was implemented in the optimum operation mode, which was effective in preventing the system performance decline and accelerated the emergence of the rotational speed control effect.

The simulation results of sunflower seeding in the laboratory with seed plates from 12 to 36 holes at working speeds from 4 to 10 km/h are presented. At a working speed of 6 km/h, the seed plate n = 12 with a rotational speed of 0.652 m/s achieved an average seeding spacing of 23.26 cm. At this rotational speed, the plate achieved a QFI of 89.15. The seed plate n = 36 with a rotational speed of 0.217 m/s achieved an average spacing of 21.76 cm with a QFI index of 98.45. At a working speed of 10 km/h, the seeding machine achieved an average spacing of 23.87 cm with a seed plate n = 12. The same seed plate achieved a rotational speed of 1.812 m/s. The seed plate n = 36 with a rotational speed of 0.602 m/s recorded an average spacing in the seeding simulation of 22.52 cm.

This paper introduces the Improved Iterated Extended Kalman Filter (IIEKF) for estimating the rotational speed, rotor resistance, and stator resistance of three-phase induction motors (IMs). Two state-space models for estimating the variables are presented. An optimal estimation of rotational speed is obtained by introducing a data fusion approach. The effectiveness of the IIEKF in comparison with the Extended Kalman Filter (EKF), using experimental data and in a wide range of operating conditions, is shown.

A full-dimensions 3-D numerical model based on the Lagrangian approach has been employed to predict the peak temperature and the plastic strain distribution in the FSW of (AA5754) joints using ABAQUS software. The material’s model utilizes the classical plasticity model in addition to defining the thermophysical properties of the alloy using JMatPro software to increase the accuracy of the numerical results. The basic variables of FSW were three rotational speeds (930, 1460, and 1860 rpm) and three traverse speeds (35, 65, and 95 mm/min). The influence of the rotational and traverse speed on temperature profile and plastic strain has been studied. The simulation results showed that increasing the rotational speed led to increasing the peak temperature, which concentrated under the tool’s bottom surface while increasing the traverse speed decreased the peak temperature recorded. The highest peak temperature was (497 oC) at a rotational speed of (1860 rpm) and a traverse speed of (35 mm/min). It was also found that the rotational speed increased the plastic strain starting from the tool’s neck and continuing along the pins’ position and gradually decreasing towards the bottom. In addition, a V-shape pattern has appeared in the temperature distribution across the workpiece’s cross-section, representing the heat loss during the FSW by the backplate due to heat conductance.

The aim of this study was to predict the temperatures on all surfaces of three-dimensional models using the ANSYS 15.0 program. Firstly, the temperatures from the welding centre to the edges of the models of two aluminium alloys (AA-7075 & AA-2024) welded by friction stir welding process were perceived. Secondly, the distribution of temperatures from the start of the welding process to its end and the derivation of equations to predict the distribution of temperatures with the time spent in the welding process, along with the distribution of temperatures with the distance from the centre of the welding process were observed at different travel speeds of the welding cart (TS = 20, 40, 60, 100 mm/sec) and different speeds of the welding tool (TRS=900, 1050, 1200 rpm). The results indicate that the temperature increases with the increase in the rotational speed of the welding tool, while the temperature decreases with the increase in the travel speed of the welding cart. Another result is that the temperature distribution is not symmetrical. The highest values are in the welding centre and decrease significantly as the welding centre is moved away, and the highest temperatures can be reached between (75 – 80%) in the welding centre from the melting point of the two aluminium alloys welded together. It was also found that the temperatures increase significantly twenty seconds after the beginning of the welding process and, afterwards, the increase is small, and three equations were derived to predict the temperature distribution.

Sand erosion is usually severe for hydraulic turbine operated in sediment-laden river hydro-power plant. Continuous erosion and abrasion in hydro-turbine components not only deteriorate the turbine performance but also bring frequent maintenance work. Thus, special attentions should be paid to anti-erosion performance besides the efficiency and stability during the hydraulic design stage. In this paper, the performances of a prototype Francis turbine used for a high head heavy sediment power station were investigated by reducing the rotational speed and using splitter runner. The hydraulic performance, anti-erosion characteristics and cavitation performance were focused and analyzed. The results proved that the velocity in the runner can be effectively reduced by lower the rotational speed, but the rotational speed reduction was also limited by the efficiency and velocity near the guide vane. The splitter runner can significantly improve the disorder flow in runner by re-distributing the velocity field. The erosion resistance of guide vane can be improved by increasing the pitch diameter of the guide vane appropriately. 3100 h of operation after commissioning further confirmed the anti-erosion and stability performance of the designed Francis turbine. This research provide a good reference for the Francis turbine design operated in heavy sediment hydro-power plant. [ABSTRACT FROM AUTHOR]

Introduction: The effect of the rotational speed on the performance of endodontic therapies has been unclear. This study aimed to evaluate the foraminal deformation (FD) caused by two rotary instrument systems with different rotational speeds at three different working length determinations using Scanning electron microscopy is better (SEM). Materials and Methods: Sixty mesiobuccal root canals of maxillary molars were randomly divided into two groups (n = 30 each) and instrumented using either RaCe®Evo (at 1000 rpm and 1 Ncm torque) or TruNatomy (at 500 rpm and 1.5 Ncm torque) 1 mm behind the major foramen (MF) (n = 10), at the MF (n = 10), and 1 mm beyond the MF (n = 10). The roots were scanned under SEM at × 300 magnification and 15.00 kV before and after instrumentation procedures. The pre- and postoperative SEM images were analyzed using the ImageJ software program. The FD was represented with the circularity and Feret's diameter ratio of the apical foramen. Results: No significant difference was observed in the before and after values of the circularity and Feret's diameter parameters within and between the rotary instrument groups (P > 0.05). Conclusion: Increasing of the rotational speed had no negative effect on the FD. [ABSTRACT FROM AUTHOR]

The present work aims to develop a computational procedure for investigating the vibration behaviour of pre-twisted laminated composite shell containing graphene inclusions in their matrix. According to nanoscopic empirical equations, graphene's mechanical properties are determined by its size dependence. It has been demonstrated that the orthotropic mechanical properties of composite laminates made from carbon fibres and hybrid matrix can be evaluated. Based on pre-twist and geometric configurations, finite element methods have been used to model hybrid materials shells that include carbon fibre, graphene, and graphene-fibre reinforcement. As part of the validation process, the proposed method is compared with other methods when possible. Finally, the vibrational behaviour of the composite shell is extracted by imposing a twisted angle on a cantilever boundary condition. An analysis of vibrations for each configuration is presented in this paper, as well as the effects of graphene inclusions on natural frequencies. As graphene volume fractions in the matrix increase, the natural frequencies of every mode also increase. When the hub radius and rotational speed are increased, the frequency parameter increases with an increase in graphene volume in the hybrid polymer composite pre-twisted shell. [ABSTRACT FROM AUTHOR]

Rotational speed has an important influence on the performance of coating materials. The a-C:Ta composite coatings were prepared by controlling the substrate rotational speed during deposition process using PVD technique. The results showed that the coating transformed from dense structure to columnar structure. Due to the changes of deposition time and the vapor incident angle of the sputtering ions, the sp2 hybrid structure increased and the C–Ta bonds contents decreased as a function of the rotational speed, which led to the improvement of adhesion force. The average friction coefficient of the composite coatings did not fluctuate significantly for the amorphous carbon matrix and the transfer films formed during friction, while the wear rates were gradually increased. The sample at 0.5 rpm possessed the lowest wear rate, which was mainly associated with the cooperative behavior of the dense structure and the formation of TaC nanoclusters in the composite coating. [ABSTRACT FROM AUTHOR]

Copyright of Eurasian Physical Technical Journal is the property of E.A. Buketov Karaganda University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The impeller is a critical rotating part of a centrifugal pump where the energy transfer to the fluid takes place. The complex nature of the fluid flow inside the impeller can give rise to cavitation which is highly undesirable. Design and operating conditions in the impeller influence the extent of cavitation. The effect of the outlet pressure, temperature and rotational speed of the impeller was studied using ANSYS CFX Computation Fluid Dynamics (CFD) software. The impeller geometry was meshed with high-quality hexahedral meshes and the y + values around the blade surface are less than 2. The k - omega turbulence model was used along with the ZGB model of cavitation. The effects of the variable parameters on the cavitation volume and the head developed were extensively studied. The numerical trends are similar to those presented in the literature. By carefully controlling the outlet pressure, the effects of increased temperature can be mitigated. Thus, it is possible to operate a centrifugal pump at higher working fluid temperatures by operating the pressure above 275 kPa. [ABSTRACT FROM AUTHOR]

The friction spot welding (FSpW) method was used to weld 2198-T8 Al-Li alloy at rotational speeds of 500 rpm, 1000 rpm, and 1800 rpm. It was shown that the grains in the FSpW joints were transformed from "pancake" grains to fine equiaxed grains by the heat input of welding, and the reinforcing phases of S' and θ were all redissolved into the Al matrix. This leads to a decrease in the tensile strength of the FsPW joint compared to the base material and a change in the fracture mechanism from mixed ductile-brittle fracture to ductile fracture. Finally, the tensile properties of the welded joint depend on the size and morphology of the grains and their dislocation density. At the rotational speed setting of 1000 rpm in this paper, the mechanical properties of welded joints consisting of fine and uniformly distributed equiaxed grains are best. Therefore, a reasonable set of the rotational speed of FSpW can improve the mechanical properties of the welded joints of 2198-T8 Al-Li alloy. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Petroleum Research & Studies is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)