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The longitudinal vibration of the propulsion shaft system is a challenging issue for marine noise management. We conducted various static and dynamic tests on our built test rig for the shafting system, presenting the results in this paper. By combining experimental data and the particle swarm optimization algorithm, we identified the structural parameters that are difficult to obtain. With these parameters we establish a completed theoretical model of a shaft system containing branches, analyze how and why static thrust affects vibration, and give quantitative results of the force transmissibility. Our work provides a reference for subsequent researchers.

A suitable index is needed for hemolysis tests that use low-flow pumps, such as pediatric blood pumps or blood purification pumps. To create such an index, the present study investigates the change of plasma-free hemoglobin in the pump circuit with time and the change of the hemolysis rate with flow rate and impeller rotational speed. The results show that the hemolysis rate or the increase rate of the total free hemoglobin are suitable measures for hemolysis evaluation for low-flow pumps. [ABSTRACT FROM AUTHOR]

The present work aims to study the effect of disk material and disk surface roughness on the oil recovery rate and oil recovery efficiency. Materials used in this study were steel, plastic, and woven fabric; two types of oil were used, namely, SAE50 and used car engine oil. The oil recovery rate was found to increase with increasing disk rotational speed. The rate of oil recovery ranged from 88.19 to 337.14 (mL/min) for SAE50 oil and ranged from 89.03 to 355.4 (mL/ min) for used oil depending on disk rotational speed and the type of disk. The rough steel disk performance is inferior to other disks except at high rotational speeds. Oil recovery efficiency was found to decrease with increasing disk rotational speed. The oil recovery efficiency ranged from 77 to 95.2 for SAE50 oil and ranged from 72 to 95.2 for used oil depending on disk rotational speed and the type of disk. Specific energy consumption ranged from 3.08×10−4 to 4.7×10−4 kW·h/kg of recovered SAE50 oil and ranged from 3.04×10−4 to 2.589×10−4 kW·h/kg of recovered used oil depending on disk rotational speed. [ABSTRACT FROM AUTHOR]

In this study, the heat transfer characteristics of water and three different water based nano fluids comprising of copper oxide (CuO), zinc oxide (ZnO) and titanium dioxide (TiO2) with constant 0.2% volume concentration (φ) of respective nanoparticles in a bare tube and bare tube fitted with “rotating twisted tape turbulator (RTTT)” of twist ratio (y = 2.88) inside, was examined. The flow rate of the working fluids (1–6 LPM) and the rotational speed of the twisted tape turbulator (TTT) (0-300 RPM) were considered as variable constraints and their influence on heat transfer characteristics were evaluated. It was detected that for all the working fluids, the convective heat transfer coefficient intensifies with upsurge in the flow rate and rotational speed of the TTT. A constant wall heat flux condition was used in the contemporary investigation. The literature review reveals that most of the research work focuses on the study of heat transfer characteristics in a bare tube with TTT. Minimal research work has been carried out on the usage of ‘rotating twisted tape turbulators’ using nano fluids as working fluid to augment the heat transfer characteristics. Further, the results indicate that the heat transfer characteristics may be enhanced by rotating the twisted tape turbulator at 300 RPM in a plain tube and by maintaining the flow rate of the working fluids at 6 LPM. [ABSTRACT FROM AUTHOR]

This research hypothesizes that tidal and earthquakes are induced by solar system planet positions, as the planetary attraction act as a trigger force change the speed of the Earth rotation. The occurrence of a sea tide is only a consequence of a relative slowdown of the rotational/revolving speed of the Earth which urges the Earth’s plates to move. The research included analyzing earthquake data for the whole Earth over July, 2019 with a case study of the Arabian Plate (AP) seismicity included the Zagros Folded Belt (ZFB) and Zagros Thrust Zone (ZTZ) as a seismic active belt in the northern hemisphere. The rotational velocity of the Earth has been calculated for eight seismic events, and it turns out that the velocity was different for each case. A negative proportional was found between earthquake and the Earth rotational speed. During the configuration of the Jupiter and Saturn in a straight line with the Earth over July 2019, one thousand and thirty-seven of earthquakes occurred around the world were statistically analyzed having 2–6 magnitudes. Rotational/ revolving speed, angular momentum and rotational inertia kinetic energy; gravitational potential energy of the Earth at equator and at 45 degrees were computed to show how rotational speed triggering plates. Planets interact with each other influencing earthquakes via the gravitational stresses arising from the configuration of the solar system planets that cause a slowdown of the rotational/revolving speed of the Earth. This stimulates the Earth’s plate to move generating earthquake due to the activation of faults. [ABSTRACT FROM AUTHOR]

Today, in sheet metal forming processes, a new concept of fabricating consolidated sheets or in other words Tailor Welded Blanks emerged. Friction Stir Welding is one method for manufacturing TWBs and has numerous advantages over fusion welding methods for joining aluminum sheets. In the present study, TWBs made by friction stir welding of 6061-T6 and 5754-O aluminum alloys were studied. The effects of different tool rotational speeds and welding speeds on the mechanical properties and microstructural characteristics of dissimilar joints were evaluated. The results showed that in an appropriate range of speeds combinations, an optimum rotational speed exists at which maximum strength is achieved. Regarding welding speed, greater strength is attained at higher speeds. The microstructural analysis confirms that an increase in welding speed will result in grain size reduction and consequently higher tensile strength. It is observed that above the optimum rotational speed, the grain size of the nugget zone increases which results in decreasing tensile strength. With regard to elongation, it is found that despite the grain growth of the nugget zone at a higher ratio of tool rotational speed to welding speed, the elongation improved due to the dominant material existing in the weld zone. Positioning Al 6061 on the advancing side of the dissimilar joints leads to improved mechanical properties compared with positioning on the retreating side. It is notable that the degree of such improvement in ductility is much more remarkable than strength, which is valuable regarding formability concerns.

In order to study the meshing thermal characteristics of the differential bevel gear under differential conditions， based on the thermal elastohydrodynamic lubrication theory， an unsteady thermal elastohydrodynamic lubrication model of straight bevel gears is established， and the temperature field of planetary gear is analyzed under differential condition. Firstly， the thermal characteristics of planetary gear and half-shaft gear under non-Newtonian fluids are studied. Secondly， the temperature field changes of planetary gear under differential conditions are studied with different tooth width and modulus. Finally， the temperature field variation of planetary gear with different rotational speed is studied. The results show that the temperature distribution of planetary gear across tooth width direction is different， the maximum temperature of the planetary gear body increases with the increase of tooth width， and decreases with the increase of the modulus. The temperature of the contact area between differential planetary gear and half-shaft gear increases as the rotational speed increases. This study provides a theoretical basis for the design of differential bevel gear lubrication.

This paper presents the design of a permanent magnet generator for a gearless backyard wind turbine. The magnetisation characteristics of the rotor steel and the stator at different field strength ranges were considered at the design stage and mathematically described using a model in Matlab. The detailed calculations and the design of the planar model were carried out using FEMM software. The high-quality results obtained from the calculations shown in the paper made it possible to make a real model of the generator. This paper presents views of the stator package, the rotor, the entire generator and selected test results. The parameter of this turbine that distinguishes it from a wide range of manufactured generators is its low, non-standard rotational speed and low breakaway torque, which allows the power plant to start in winds of approximately 2 m/s. Other advantages of this generator is its low weight resulting from the use of a light rotor and light alloys for the generator housing.

Centrifugal casting process, in both horizontal and vertical mode, is considered as an efficient method to produce bimetallic components. Al/Cu65Zn35 couples were prepared by the vertical centrifugal casting process. In this study, different volume of molten aluminum having melt-to-solid (m/s) volume ratios (VR) of 1.5 and 2.5, were cast into preheated brass bush rotating at 800, 1600, and 2000 (rpm), respectively. The thickness of the interface, which is composed of three different zones, is depended on the rotational speed and the (VR) and was at least 490µm (at VR=1.5 and 2000 rpm) and at most 1480 µm (at VR=2.5 and 800 rpm). The results of optical microscopy, energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction analysis showed that the interface layers are composed of Al2Cu5Zn4, Al3Cu3Zn, Al2Cu precipitates dispersed in the matrix and finally α-Al/Al2Cu anomalous eutectic structure near the aluminum side. Gas pore entrapment and oxide film entrainment defect was detected within the interface next to the aluminum base metal.

Controlling the rotational speed of brushless DC (BLDC) motor is an essential task to improve the transient and the steady state performances under loaded condition. Rotational speed control of BLDC motor using genetic algorithm optimized proportional-derivative (PD) controller to form what the so-called the genetic algorithm-PD (GA-PD) controller is proposed in this paper. Control system is realized in a microcontroller namely a 16MHz Atmega2560 with an absolute encoder as a position sensor. The effectiveness of the GA-PD controller is tested under constant and varying step functions with the Ziegler-Nichols-PD (ZN-PD) controller as a benchmark. Experimental results show that the GA-PD controller has slower speed than the ZN-PD controller, but the latter has overshoot and small oscillations during its steady state condition as a consequent of having a fast rise time.

The influences of the pin geometry and rotational speed on the microstructure evolution and mechanical properties of the AA 5052-H112 FSSW joint were investigated. Results showed that hook height and fully bonded region (FBR) width were significantly dependent by both pin geometry and rotational speeds. Both pin geometry and tool rotational speed had an apparent influence on the strength of the weld. At 900 and 1400 rpm, the strength of welds prepared using a cylindrical pin was higher compared to that of a step pin. For the step pin, the cross-tension strength of the welds increased as rotational speed increased. For cylindrical pin, the tensile/shear and cross-tension loads achieved the maximum values of 3589 and 3419 N at 1400 rpm, respectively. Under tensile/shear loading, shear and tensile/shear fractures were observed. On the other hand, under cross-tension loading, two types of fracture modes, namely nugget debonding and nugget pull-out were detected.

This study examined the effect of AISI H13 steel-tapered tool on the dissimilar friction stir welding of 7075-T651 and 1200-H19 aluminium alloys. Three mechanical tests which include hardness, tensile strength and impact energy were conducted to study the effect of tilt angle, rotational and welding speeds on the weld integrities, 50 and 175 HV were respectively obtained as hardness values for AA1200- H19 and AA 7075- T651, the hardness values were measured for three selected welding speeds of 30, 60 and 90 mm/min representing low, medium and high at a constant rotational speed of 1500 rpm, a tool tilt angle of 2°.The hardness increases with the welding speed from 81.99 to 98.5 HV as the speed increased from 30 to 60 mm/min and dropped to 77 HV at 90 mm/min.The impact energy increased from 12.9 to 21.4 J with an increase in the welding speed from 30 to 60 mm/min and dropped to 5.4 J at 90 mm/min.The ultimate tensile strength (UTS) increased from 126.04 to 151.54 MPa with an increase in the welding speed from 30–60 mm/min and decreased from 151.54 to 128.37 MPa, the hardness at 1500 rpm and 60 mm/min increased from 70.22 to 98.58 HV with an increase in the tilt angle from 1- $${2^^\circ }$$, a further increase from 2–3 o reduced the hardness from 98.58 to 66 HV, UTS increased from 123.32 to 151.54 MPa as tilt angle increased from 1–2 ° and decreased to 122.2 MPa, the medium tilt angle of $${2^^\circ }$$,rotational and traverse speeds of 1500 rpm and 60 mm/min respectively gave the highest impact energy of 21.4 J.

As the progress of the high‐speed performance requirement for porous gas journal bearings continuing, the aerodynamic effect, which plays a key role in the state of lubrication, causes the porous gas journal bearings being gradually to be used as hybrid bearings. This paper firstly presents a theoretical analysis on the lubrication mechanism of the hybrid bearings. The gas flow in the porous and clearance is modelled by using the mass continuity equation. Two experimental test rigs are designed to systematically test the static and dynamic characteristics of the hybrid bearings. The numerical results are corroborated by the experimental data. Results show that there is optimal clearance for hybrid bearings to obtain maximum load capacity. The load capacity of the hybrid bearings is increased by the aerodynamic effect to be higher than that of pure aerostatic bearings especially at higher rotational speed and larger eccentric ratio. However, due to the occurrence of the aerodynamic effect, the hybrid bearings show clear cross‐coupling dynamic coefficients, which may lead to bearing instability. It is interesting to note that the direct dynamic stiffness and damping coefficients are both influenced by the aerodynamic and aerostatic effects. Higher rotational speed and external supply pressure will result in higher direct dynamic coefficients. [ABSTRACT FROM AUTHOR]

The mechanical vibration causes health issues to drivers, such as backache, spinal cord injury, etc. In this regard, a tractor engine plays important role. Tractors without chassis are equipped with a balancer unit reducing the secondary engine vibrating force and decreasing the engine and tractor vibration. The paper presented investigates the effects of balancer on secondary vibration. In this research, the root mean square (RMS) of vibration was computed for specific periods of engine work. Effects of rotational speed and engine load on engine vibration in two modes with and without balancer were investigated. The results showed that, at full engine load, increasing the engine speed resulted in increasing the vibration in both observed modes. Balancer utilization reduced the vibration by 22.3% on average. At fixed rotational speed, increasing load caused an increase in vibration in both observed modes. At 1400 rpm rotational speed and 125 Nm torque, balancer utilization managed to reduce the RMS of secondary vibration by 38.9%. Furthermore, at 250 Nm, RMS vibrations were reduced by 21.3% in comparison to no balancer mode. At full load, variable rotational speed, the balancer significantly reduced vibration by 29% on average. The balancer proved to be more efficient at lower torques. [ABSTRACT FROM AUTHOR]

The Vertical Axis Hydrokinetic Turbine -- Straight Blade Cascaded (VAHT-SBC) is a type of energy generation technology developed to meet the increasing demand for renewable energy. Previous studies have been carried out to enhance the efficiency of the turbine through several aspects. To deploy a turbine on site, a study on its power generation and conversion is needed. In this research, the VAHT-SBC was integrated with a permanent magnet synchronous generator (PMSG) by a pulley and belt transmission system. This study was conducted by experimental and numerical analysis. The CFD simulation result showed that the highest torque of the turbine was found at 0° and 360°, with an average value of 23.923 Nm and with current velocity at 0.92 m/s. The experimental data showed that the voltage and frequency were proportional to the generator rotational speed and inversely correlated with the load given to the integration system. In the inverter, the voltage and frequency values were stable at 230 V and 56 Hz respectively. The VAHT-SBC prototype was able to produce a maximum power of 50 W on site, with a current velocity of 0.82 and 0.92 m/s. [ABSTRACT FROM AUTHOR]

This study examined the effect of AISI H13 steel-tapered tool on the dissimilar friction stir welding of 7075-T651 and 1200-H19 aluminium alloys. Three mechanical tests which include hardness, tensile strength and impact energy were conducted to study the effect of tilt angle, rotational and welding speeds on the weld integrities, 50 and 175 HV were respectively obtained as hardness values for AA1200- H19 and AA 7075- T651, the hardness values were measured for three selected welding speeds of 30, 60 and 90 mm/min representing low, medium and high at a constant rotational speed of 1500 rpm, a tool tilt angle of 2°.The hardness increases with the welding speed from 81.99 to 98.5 HV as the speed increased from 30 to 60 mm/min and dropped to 77 HV at 90 mm/min.The impact energy increased from 12.9 to 21.4 J with an increase in the welding speed from 30 to 60 mm/min and dropped to 5.4 J at 90 mm/min.The ultimate tensile strength (UTS) increased from 126.04 to 151.54 MPa with an increase in the welding speed from 30–60 mm/min and decreased from 151.54 to 128.37 MPa, the hardness at 1500 rpm and 60 mm/min increased from 70.22 to 98.58 HV with an increase in the tilt angle from 1- 2 ° , a further increase from 2–3 o reduced the hardness from 98.58 to 66 HV, UTS increased from 123.32 to 151.54 MPa as tilt angle increased from 1–2 ° and decreased to 122.2 MPa, the medium tilt angle of 2 ° ,rotational and traverse speeds of 1500 rpm and 60 mm/min respectively gave the highest impact energy of 21.4 J. [ABSTRACT FROM AUTHOR]

The mixing and separating process of different-sized particles in a self-designed rotating drum were explored, where the glass beads were taken as particles. The power consumption of rotating drum under different operating parameters were measured. The results show that the particle separation is more evident when the drum is operated at high fill level, where the small particles surrounded by large particles are mostly observed. When the filling rate is low, it is unobvious for the particle separation of the similar size particles at different rotating speeds. The larger difference of the particle size, the more particle separation occurs. With the increasing rotational speed and fill level, the power consumption increases, while the power consumption is relatively less sensitive to the particle size ratio. [ABSTRACT FROM AUTHOR]

In this work, rotary friction welding processes of dissimilar AA7075/AA5083 aluminium alloy rods with the diameter of 15 mm were performed at varying rotational speeds, typically 370 to 2500 rpm. The aim of this research is to improve mechanical properties, in particular, strength and fatigue performance of the weld joints. Several experiments including macro and microstructural examinations, Vickers microhardness measurements, tensile tests, fatigue tests and residual stress measurements were carried out. Results showed that at higher rotational speeds, typically 540 rpm or above, the dissimilar AA7075/AA5083 rotary friction weld joints revealed a static fracture in the AA5083 base metal side, indicating that the joint efficiency is more than 100%. It seemed that the best weld joint was achieved at the rotational speed of 1200 rpm, in which the friction heat was sufficient to form metallurgical bonding without causing excessive flash and burn-off. In such a condition, the fatigue strength of the weld joint was slightly higher than AA5083 base metal, but it was lower than AA7075 base metal. It was confirmed that the crack origin is observed at the interface followed by fatigue crack growth towards AA5083 side, and the growth of crack seemed to be controlled by microstructure and residual stress.

The purpose of this study is to investigate the effect of drying parameters on drying performance in an air-vented tumble dryer, and to optimize its drying performance by adjusting parameters. The critical drying parameters that influenced specific moisture extraction rate (SMER), final moisture content, evenness of drying, and smoothness appearance were determined by the analysis of variance in JMP software, which were rotational speed of the motor and load size, with clearly significant individual effects and binary interactions. In order to improve the applicability of the outcomes obtained in this study and to take into account the interactions between drying parameters and drum structure parameters on drying efficiency, non-dimensional analysis was used and the correlation between drying efficiency and dimensionless variables was studied. The Buckingham Pi theorem was applied to the problem to derive dimensionless Pi terms upon which the drying efficiency depends. A step regression analysis was then conducted to test the assumption that SMER was influenced by the dimensionless parameters based on the standard least squares fitting. Results indicated that the regression model showed an explanatory power of 73.8%. By adjusting the dimensionless parameters in the model, an optimized energy-saving drying program was obtained with the desirability goal of reducing the value of SMER. Compared with the original program, energy efficiency was improved by 32.4%. [ABSTRACT FROM AUTHOR]

A mechanical peeler cum juice extractor was designed and developed for simultaneous peeling and juice extraction of kinnow and sweet orange fruits. Based on the designed components and prior optimization of operational parameters for peeling of both the fruits, a functional machine was developed. Major components of the machine include spur gear assembly (Φ 102 mm and Φ 76 mm), two fruit holders (Φ 30 mm), revolving shaft with length 570 mm, clearance of the tool for peeling 25 mm and cutting knife with length 80 mm, respectively. This peeler was operated using a motor, gear assembly and the combination of pulleys. The juice extractor was also fitted with a conical hopper having a flattened base to facilitate the juice extraction of peeled fruits. For performance evaluation, fruit rotation speed was considered as independent parameter and was varied at 220, 260, 280, 300, 360 rpm, whereas peeling time (s), peeling efficiency (%), peel remained on fruit (%) and juice loss (%) were taken as dependent parameters. The machine resulted in best performance at fruit rotational speed of 220 rpm (kinnow) and 260 rpm (sweet orange) with higher peeling efficiency and minimum juice loss. The capacity for peeling and juicing operation was 60–90 kg/h (kinnow) and 50–60 kg/h (sweet orange), respectively. This composite peeling cum juice extractor machine can find its applicability in cottage citrus fruit juice processing industries as well as for the domestic juice sellers. [ABSTRACT FROM AUTHOR]

A new fire-extinguishing technology in an inhabited pressurized compartment of manned spacecraft with simulated gravity created for prevention of negative influence of zero-gravity on cosmonauts during a long-term spaceflight is presented. The new fire-extinguishing technology in an inhabited pressurized compartment of a manned spacecraft involves selection of polymeric materials, which are not combustible in simulated gravity conditions and generation of momentum of reaction force in the direction opposite to the direction of its rotation for the time, during which the angular velocity of rotation of the spacecraft module is reduced to the value, under which gravity acceleration is decreased up to the value of combustion limit by gravity acceleration of the most combustible polymeric materials at all the points of the inhabited pressurized compartment during fire occurring inside the pressurized compartment with simulated gravity simultaneously with the activation of automatic fire-extinguishing system, which operation is based on the immediate decrease of ventilation flow velocity lower that combustion limits by to gravity acceleration of the most combustible polymeric materials. • Research results of limiting combustion conditions under decreased gravity accelerations are considered. • Design of fire-extinguishing technology in INPC SC during the flight with simulated gravity is studied. • Scientific basis for design of fire extinguishing means in InPC SC in simulated gravity mode gravity is analyzed. • Arrangement of experimental installations recommended for calculation of G lim value of materials is presented. [ABSTRACT FROM AUTHOR]

The speed regulating differential mechanism (SRDM) enables grid‐connected wind turbines (WTs) to generate constant‐frequency electric power without fully‐ or partially‐rated converters. In this study, the authors present a self‐stabilising SRDM (SS‐SRDM) consisting of a planetary gear train (PGT), a differential mechanism, and a constant speed motor for WTs to dislodge the high‐cost speed sensors, servo motor and the complicated control system from the electrical controlled SRDM. The kinematic principles and the four‐axis dynamic characteristics of SS‐SRDM are studied. An effective parameter configuration method for tuning the speed ratios of five key connection units is also proposed and used to obtain a PGT with optimal structural parameters. The detailed simulation model of a 3 MW WT with SS‐SRDM is established and then validated through physical experiments. Results show the satisfactory accuracy of the built model (maximum steady‐state errors in output shaft and speed regulating shaft are, respectively, 0.76 and 1.95%). Finally, case studies and verification work of the proposed methods are carried out, in which the rotational speed, power, speed error, and power ratio among wind rotor, SRM, and synchronous generator are obtained. Case studies well‐illustrate the availability of parameter design and the effectiveness of speed‐regulations of the proposed SS‐SRDM method. [ABSTRACT FROM AUTHOR]

This work reports a study on a tidal current system named GEMSTAR, composed of two hydrokinetic turbines supported by a floating submerged structure. A flexible mooring cable links the floating support to the seabed allowing the free rotation of the system and its alignment to changing current direction. The work is mainly focused on the design of the turbine blade with two objectives: keeping a constant power output above the rated power condition and limiting the thrust increase between rated and maximum operating speed. A fixed pitch blade was considered, in order to reduce the costs associated to a complex pitch control mechanism. An analytical procedure for blade design is proposed and validated by comparison to other numerical methods. Above the rated current speed, the power is held constant while the rotational speed of the turbine and of the generator increases, assuming an over‐speeding control strategy. The adopted design configuration relies on the possibility of the generator to operate in de‐fluxing working conditions. As reported in the last part of this study, a numerical model of the generator has also been developed and applied to a test case in order to analyse the electric behaviour of the system. [ABSTRACT FROM AUTHOR]

We aimed to evaluate the additional debulking efficacy of low-speed rotational atherectomy (RA) after high-speed RA by using intravascular imaging. A total of 22 severe calcified coronary lesions in 19 patients (age, 74 ± 10 years; 74% male) were retrospectively analyzed. All of these lesions underwent RA under optical coherence tomography (OCT) or optical frequency domain imaging (OFDI) guidance. At first, we performed high-speed RA with 220,000 rpm until the reduction of rotational speed disappeared; then, low-speed RA with 120,000 rpm using the same burr size was performed. OCT or OFDI was performed after both high-speed and low-speed RAs, and the minimum lumen area were compared. The initial and final burr sizes of high-speed RA were 1.5 (1.5–1.75) and 1.75 (1.5–2.0) mm, respectively. The number of sessions, total duration time, and maximum decreased rotational speed during high-speed RA were 11 ± 5 times, 113 ± 47 s, and 4000 (3000–5000) rpm, respectively. During low-speed RA, the number of sessions, total duration time, and maximum reduction of rotational speed were 3 ± 1 times, 32 ± 11 s, and 1000 (0–2000) rpm, respectively. The minimum lumen area was similar between after high-speed and after low-speed RA [2.61 ± 1.03 mm2 (after high-speed RA) vs. 2.65 ± 1.00 mm2 (after low-speed RA); P = 0.91]. Additional low-speed RA immediately after sufficient debulking by high-speed RA was not associated with increased lumen enlargement. There was no clinical efficacy of low-speed RA after high-speed RA. [ABSTRACT FROM AUTHOR]

The growing demand for electricity in developing countries is a source of concern and therefore it is necessary to explore other methods of energy generation in which one of the methods is considered in this study. The power generation is through a bladeless turbine that operates on incompressible fluid and has a renewable energy source that is available throughout the year. The flow model (Laminar flow) is linearized for experimental design and construction of a prototype bladeless turbine with an incompressible air medium and inclusion of air moisture regulator (ATR). The introduced ATR device is connected to the air hose that linked up with the inlet nozzle to filter the airflow moisture and it has a strong influence and yielded better performance on the turbine output. The findings are presented graphically and discussed for the bladeless turbine performance to portray the impacts of the important embodiment parameters. The experimental bladeless turbine Reynold’s number Re ​≤ ​528.53 and rotational speed ≤944.31 ​rad/s operating within the laminar range of efficiency 23.9% while model efficiency is 34%. The efficiency comparison of the analytical solutions model to the experimental (prototype) bladeless turbine revealed a notable divergence, but the correlation between calculated theoretical results and the experimental (prototype) results are significant. The comparison, correlations amid performance parameters with the introduced ATR device connected to the air hose that linked up with the inlet nozzle to filter the airflow moisture are examined in the experiments and the results are analyzed using Graphpad 5.0 computer software.

Introduction It is common to use rod weeders for onion harvesting according to their prevention of root blocking in front of the machine and separation of onion bulbs from soil by shaking. Chesson et al., (1977), used a rod weeder for manufacturing an onion harvester. This machine had a rectangular rotor axis with 25mm×25mm cross section. The rotor power was provided by a hydro-motor. An investigation into onion losses during the harvesting operation showed that the majority of crop damages have been occurred due to the collision of rods with onion bulbs. Therefore, the objective of this study is to design and evaluate an onion harvester based on rod weeders with the capability of crop harvesting with minimum damage. Materials and Methods The main components of the examined onion harvester are chassis, furrower, and power transmission system and excrescence axes. Rectangular 100mm×100mm and 40mm×80mm profiles with 4mm profile thickness are used to fabricate the chassis. The furrowers were installed on each side of the chassis as the first parts of the harvester that comes into contact with the soil. Power transmission system provided rotation of two axes from both sides of the machine due to the lack of space for working of two chains on the one side. Therefore, a gearbox having one input shaft and two output shafts was selected for the machine. The gearbox output shafts turn the rotors with a reduction ratio of 1 to 3.5. The rotary motion of the excrescence axes cuts and moves the soil located under the onions bulbs upward and finally the onion bulbs are placed on the soil surface. Therefore, excrescence axes can be considered as the main part of the onion harvester. The excrescence shape of the axes were created by star wheels. Star wheels had a hole with a square section in center (30mm×30mm), for installing them on their shaft. Choosing this kind of the connection, dose not let star wheels to move freely. Also to limit the lateral movement of the star wheels on axis, metallic spacers were used between the adjacent pairs of them. To evaluate the machine performance three variable factors were defined: working depth (20 and 26 cm), forward speed (3, 4.5 and 6 Km h-1) and rotational speed of the excrescence axes (150, 220 and 290 rpm). The conducted experiments were analyzed in a complete randomized design with three replications. Results and Discussion The analysis of variance showed that the working depth and forward velocity of axis had significant effect (in 5% level) on the success rate of onion harvester. Also the interaction between depth and forward velocity and the interaction between rotational speed of axes and forward speed were significant. The interaction between depth and rotational speed of axes and the interaction between depth, rotational speed of axes and forward speed were not significant. Evaluation of the interaction between depth and forward velocity showed that the most success rate of onion harvesting was in 20 cm depth and forward velocity equal to 3 and 4.5 km h-1. The least success was gained in 26 cm depth with 4.5 and 6 km h-1 forward speed. Evaluation of the interaction between rotational speed of axes and forward speed showed that the most success in the onion harvesting was occurred with a machine having 3 km h-1 forward velocity and 150 rpm rotational speed and also 4.5 km h-1 forward velocity and 220 rpm rotational speed. Conclusions The success rate of the onion harvesting decreased by increasing the working depth of the machine and axes distance to the onion bulbs. Also with excessive forward velocity the success rate of onion harvesting decreased because of difficulties in controlling the tractor guidance in straight line. The best performance of this onion harvesting machine was in 20 cm depth, 4.5 km h-1 forward velocity and 220 rpm axes rotational speed. Adjusting the machine working parameters according to these values, the ratio of the linear speed of the star wheel tips to the forward velocity of the machine (kinematic index) was equal to 0.82.

The main objective of the present work was to investigate the effect of tool rotational speed on the mechanical and microstructural properties of aluminum based metal matrix composites (AA 6061 alloy reinforced with 15% of Al2O3 particles). The welds were produced by varying the rotational speed from 630 to 1250 r/min while the chosen welding speed was 80 mm/min for analysis. It was found from the analysis of the microstructure that the changing of the rotational speed leads to variation of the grain size and also the fragmentation and improvement of Al2O3 particles distribution in nugget zone. Moreover, the obtained results clearly depicted that increasing rotational speed from 630 to 1250 r/min resulted in improvement of the wear resistance and also decreases the fluctuations of friction coefficient which can be attributed to the presence of Al2O3 particles which acted as barriers and restricted the grain growth in nugget zone. The lowest wear rate was achieved at welds produced at rotational speed of 1250 r/min. It was seen from the hardness results that the highest tensile strength value was obtained for 1250 r/min rotational speed with an average value of about 320 MPa (equivalent to 82% that of the base metal).

The bone drilling process is indispensable in orthopaedic surgeries and treating bone breakages. It is also very important in dentistry and bone sampling operations. Bone is a very complex material and the process of drilling is very sensitive. Thus, bone drilling is one of the most important, common in the field of biomedical engineering. The bone drilling process can be promoted using automatic drilling machines and surgery-assisting robots. The problematic issue during operation is the high increase in drilling process temperature (higher than 47 °C) which leads to the so-called ‘thermal necrosis’ or cell death, and local burn in bone tissue. Furthermore, imposing higher forces to bone might yield to breaking or cracking, and consequently causes serious damages in bone. In this paper, the tool rotational speed, feed ratio and tool diameter were taken into account as process input parameters, and process temperature and thrust force were taken as output parameters. Design of experiments using response surface methodology was followed. Then, second linear governing equation was assigned to the model and its accuracy was evaluated. Later, Sobol statistical sensitivity analysis was used to ascertain the effect of process input parameters on process temperature and force. The results showed that among all effective input parameters, the tool rotational speed, feed rate and tool diameter have the highest influence respectively on process temperature and force. The behaviour of each output parameter with variation in each input parameter was further investigated.

This article presents a method for detecting rotational speed by LC (inductor-capacitor) wireless sensors. The sensing system consists of two identical LC resonant tanks. One is mounted on the rotating part and the other, as a readout circuit, is placed right above the rotating part. When the inductor on the rotating part is coaxially aligned with the readout inductor during rotation, the mutual coupling between them reaches the maximum, resulting in a peak amplitude induced at the readout LC tank. The period of the readout signal corresponds to the rotation speed. ADS (Advanced Design System) software was used to simulate and optimize the sensing system. A synchronous detection circuit was designed. The rotational speed of an electric was measured to validate this method experimentally, and the results indicated that the maximum error of the rotation speed from 16 rps to 41 rps was 0.279 rps.

Industrial practitioners are working on predictive solutions for the precise evaluation of input parameters and processed surfaces of engineering materials. To aid the aeronautical industry, this study is an effort to develop the mathematical modelling for comprehensive surface analysis of input parameters and surface finish after dry machining of CLARM HBR, a steel alloy with attractive mechanical properties and wide applications in large caliber gun barrels and high-pressure vessels. Feed rate, rotational speed, and depth of cut were taken as quantitative parameters, whereas machining time was considered as a categorical factor with a classification of three levels. Response surface methodology (RSM) with a central component design has been used for the constitution of the experimental design, mathematical modelling, and analysis of developed models. Eighteen samples were prepared to perform the experimentation for the development of prediction models. The adequacy of the developed models was verified using analysis of variance (ANOVA), and the models were validated using confirmatory trial experiments, which revealed the experimental results agreeing with predictions. The feed rate was the most significant parameter in achieving the desired surface finish. An increase in rotational speed at a low feed rate resulted in very fine surface texture, as though it deteriorated the surface finish at higher feed rates. The superior surface quality obtained was 0.137 μm at parametric settings of 0.19 mm/rev feed, 90 rpm speed, 3 mm depth of cut, and 4 min time. Overall, higher values of surface roughness were frecorded in the third level of process variable time. The developed empirical models are expected to aid manufacturers and machining practitioners in the prediction of the desired surface finish concerning different parameters before the experimentations.

Purpose: The aim of the current study was to identify the efficient fiber movements for 532-nm laser prostatectomy. Materials and methods: 532-nm Lithium triborate (LBO) laser light was tested on 120 kidney tissues at three different translational speeds (TS 1, 2, and 4 mm/s) and four different rotational speeds (RS 0.5, 1.0, 1.6, and 2.1 rad/s). The applied power was 120 W at a 2-mm working distance and 60° sweeping angle. Ablation rate and dimensions of resulting ablation craters were measured. Results: Slower TSs and RSs created deeper and wider ablation craters with thinner coagulation, leading to more efficient ablation performance. Maximal ablation rate was achieved at a TS of 2 mm/s and RSs of 0.5 and 1.0 rad/s. An RS of 0.5 rad/s accompanied surface carbonization for all the TSs. Irrespective of TS, ablation rate became saturated at faster RSs than 1.0 rad/s. Faster TSs or RSs reduced tissue ablation, but increased thermal coagulation due to a shorter interaction time. Conclusions: Optimal ablation efficiency occurred at a TS of 2 mm/s and a RS of 1.0 rad/s with a thin coagulation of around 1.0 mm and no or minimal carbonization. Further studies will validate the current findings with prostate tissue and high-power levels for laser prostatectomy. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) is extensively used due to its low processing temperature, cost, and fast operation. The objective of this is research is to determine the optimum rotational and welding speed for welding of Al/Cu butt joint by FSW. FSW is used to produce a butt joint of pure aluminum with pure copper under two conditions; as received, i.e., not annealed, and as annealed. FSW is examined under three different rotational speeds: 910 rpm, 1280 rpm, and 1700 rpm, and each rotational speed is examined at three different welding speeds 16 mm/min, 29 mm/min, and 44 mm/min. The axial and longitudinal welding force components are measured during the welding process. Tensile and hardness tests were done to evaluate the mechanical properties, and the microstructural properties were also examined by XRD, SEM, and an optical microscope. The results showed that the welding force increased and the axial force decreased as the rotational speed increased and the welding speed decreased. Voids, tunnels, and cavities are noticed in case of a low rotational speed and a high welding speed; however, almost defect-free structure obtained at the highest rotational speed examined, i.e., 1700 rpm and the lowest welding speed of 16 mm/min, in case of Al and annealed Cu joint, but in case of non-annealed copper, it was different. It can be concluded that there is an optimal combination between the rotational speed and the welding speed in order to obtain the optimum mechanical and microstructural properties of the Al–Cu-welded joints, and that speed is a function of the material conditions. [ABSTRACT FROM AUTHOR]

The rotational speed is a crucial parameter for bearing condition monitor. The present study shows the influence of the rotational speed on the impact characteristics caused by a localized defect of the outer raceway. A 2 Nb + 5-degrees-of-freedom nonlinear dynamic model for a ball bearing is developed. The waviness of bearing components, a localized defect of the outer raceway, and the centrifugal forces of balls caused by rotational speed are involved in the ball bearing model. Spectral kurtosis (SK) analysis and envelope spectrum analysis are used to extract the impact signal and confirm the position of the optimal frequency band affected by the impact signal. The peak of the impact signal rises with the increase in rotational speed. The position of the optimal frequency band affected by the impact signal is a linear piecewise function of the rotational speed. These simulated results are verified through vibration experiments of a ball bearing with a localized defect of the outer raceway under an axial load. In addition, considering both a localized defect on the outer raceway and the waviness of bearing components, only when the size of the localized defect is large enough, can the impact signal overcome the influence of the structural vibration of the system to extract impact characteristics. The case studies of high-speed spindle bearing state diagnosis show that high speed is not conducive to the extraction of the impact characteristics. [ABSTRACT FROM AUTHOR]

To enhance the power grid's stability and safety, pumped‐storage power stations (PSPSs) have to keep themselves stable and safe strictly. However, instabilities happen frequently in some PSPSs due to the S‐shaped characteristics of pump‐turbines. When the operating point goes through the S‐shaped region, intensive radial forces on the runner could cause shaft swing of the turbine‐generator unit. In this study, the runaway transient scenarios of a pump‐turbine in a model PSPS were simulated by using a one‐dimensional and three‐dimensional coupled computational fluid dynamics model, and the influence of the unit rotational inertia on the runner radial forces was investigated. The results show that when the pump‐turbine runs in the S‐shaped region, large rotational inertia is easier than a small one to induce abrupt increases in runner radial forces. The reason is that large rotational inertia gives slower changes in rotational speed and discharge, providing enough time to generate unstable and uneven flow patterns in the pump‐turbine. This indicates that apart from the running away region in the characteristics plane, the running away duration is also essential for the transient instability of a pump‐turbine. The finding is different from the traditional understandings and should be considered when selects the rotational inertia of a pump‐turbine unit. [ABSTRACT FROM AUTHOR]

The limited productivity of conventional solar still is considered as the main obstacle that restricts their implementation. Hence the objective of the current study is to enhance the productivity of conventional solar still (CSS) by increasing the evaporation area using a rotating hollow drum. Many factors have been considered in the investigation of the enhanced solar still (ESS) productivity; including environmental factors and operation factors such as drum rotational speed. Three rotational speeds have been used in the experimental tests (0.5, 1, and 3 rpm) during three typical days 12, 13, and 14 June 2019. All tests done for 12 h from 8:00 am to 20:00 pm. Study results showed that the productivity enhanced by about 161% with 0.5 rpm, 111% with 1 rpm, and 75% with 3 rpm rotational speed compared to conventional solar still. Accordingly, the productivity increased with decreasing rotational speed and the maximum value obtained at the lower speed (0.5 rpm). [ABSTRACT FROM AUTHOR]

Screw feeders and conveyors are mainly used in industries like minerals, agriculture, chemicals, pharmaceuticals, pigments, plastics, cement, sands, and food processing for transporting and mixing the granular materials. The system looks mechanically simple but the physics of particle transport in the system is complex; problems like bridging and blockage may be observed in the operation. A comprehensive understanding is required to study the granular flow behavior in screw feeders and conveyors. Hence, this extensive review has been prepared on granular flow behavior, transportation and mixing occurring in screw feeders and conveyors, via experimental, theoretical and discrete element method (DEM) approaches. Unlabelled Image • Screw feeders and conveyors are used in a wide range of applications. • Experimental, simulation and theoretical studies of these systems are reviewed. • Simulations closely predict experimental data in most studies. • Flowability and mixing of feed material are affected by moisture content. • Particle shape and size distribution is key to understand granular flow behavior. [ABSTRACT FROM AUTHOR]

The Warburg observation concerning ATP generation in cancer cells is analyzed with regard to the likely involvement of H+ resonance effects on the angular velocity of the ATP synthase rotor. It is reasonable to expect that the variety of diseases associated with mitochondrial dysfunction may in part be related to the ATP synthase rate of rotation. Experimental measurements of ATP synthase rotational rates, as found in the literature, are consistent with what might be expected from the ion cyclotron resonance (ICR) frequencies of protons moving under a Lorentz force determined by the approximate surface intensity of the geomagnetic field (~26-65 ?T). One research approach proposes that applying the electronic sum of two critical multiple resonance frequencies simultaneously may serve to more closely resemble real world biochemical changes as compared to applying these frequencies sequentially. Accordingly, it is suggested that applying the sum of the two individual resonance frequencies corresponding to H+ and H3O+ has the capacity to both increase proton density as well as couple to ATP synthase rotation. Not only will this tend to stabilize the F0 rotational rate but also perhaps make it feasible to control this rate, thereby providing a new and potentially efficacious means of treating diseases connected to mitochondrial dysfunction electromagnetically. [ABSTRACT FROM AUTHOR]

In this paper, friction stir welding process of high-density polyethylene was studied. Two tools have been chosen, concave and plate, to explore the influence of the tool on the welding quality of the material. In addition, different parameters, rotational speed and welding speed, were investigated. Tensile tests were performed after welding in order to determine the tensile strength efficiency. The greatest ultimate tensile strength was found for the plates welded by concave shoulder. [ABSTRACT FROM AUTHOR]

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This study focuses on optimization of process parameters, which may result in improved mechanical properties of the friction stir weldments of AA2014-T651. Plain taper and threaded taper cylindrical tool pin profiles were used for the study. A set of experiments was conducted at different levels of tool rotational and weld speeds using two tool pin profiles. Mechanical properties such as tensile strength, yield strength, impact strength, percentage of elongation, and hardness were measured. Objective functions are developed for the five mechanical properties in terms of input parameters. The input parameters were optimized using teaching–learning-based optimization algorithm technique to improve mechanical properties. The teaching–learning-based optimization algorithm suggested three best combinations such as combination-I (940 r/min and 32 mm/min), combination-II (1100 r/min and 40 mm/min), and combination-III (1205 r/min and 45 mm/min). The optimization is also validated with experimental results. [ABSTRACT FROM AUTHOR]

The air suction engine containing sand and dust will inevitably collide with the blade and the inner and outer casing, which will affect the flight safety of the aircraft.By using explicit dynamic analysis finite element method, the rebound model of sand and dust impacting on the wall with different incident angles， incident velocities，particle size and rotating velocities was established.The rebound characteristics of sand and dust impacting on stainless steel and aluminium alloy surfaces under different conditions were studied， which provided data support for predicting the trajectory of sand and dust in particle separator.The results show that the rebound velocity increases with the increase of the incident velocity of sand and dust， and the velocity recovery coefficient keeps stable basically； under the same incident condition, the influence of aluminum alloy on the velocity recovery coefficient of sand and dust is smaller than that of stainless steel; the impact of rotational velocity and particle size of sand and dust on the impact rebound characteristics is weak and can be neglected.The sand and dust rebound angle depends only on the collision attitude and incidence angle of sand and dust. [ABSTRACT FROM AUTHOR]

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The friction stir vibration welding (FSVW) method has been proposed as a modified version of the friction stir welding (FSW) method. In the current research, the effect of the FSVW variables on the microstructure and the mechanical properties of the joint made by this welding process was analyzed. In FSVW, the workpiece is vibrated normal to tool traverse direction while FSW is carried out. AA6061-T6 specimens were joined by FSVW as well as FSW, and the obtained joints were compared. The microstructures of the welds were analyzed using metallography techniques. SEM and EBSD were also applied to study the microstructure. The results showed that grain size reduced and hardness increased as the FSVW technique was employed instead of FSW. The results also indicated that the strength and hardness of joints, made by FSVW, increased as vibration frequency increased. It is believed that workpiece vibration, in FSVW, increases the material strain and correspondingly, enhances the dislocation density. More intensified role of dynamic recrystallization in FSVW, compared to FSW, leads to the development of finer grains in the stir zone. It was also concluded that high thermal energy during FSW and FSVW might deteriorate the mechanical properties of the joint and low thermal energy also leads to an unfair joint. [ABSTRACT FROM AUTHOR]