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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]

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]

Purpose: The purpose of this paper is to test and analyze the friction torque of double-row angular contact ball bearings under vacuum or ordinary pressure environment, horizontal or upright installation mode, and different rotational speeds, and to provide theoretical bases for the development of aerospace equipment. Design/methodology/approach: The experiments were carried out to investigate the effects of vacuum or ordinary pressure environment, horizontal or upright installation mode and different rotational speeds on bearing friction torque. To explore the relationship between working conditions and bearing friction torque, firstly, based on the generation source of friction torque, the test principle was determined, a test system was developed and the reliability of data was verified. Secondly, the friction torque of bearing was tested, and the values under various working conditions were obtained. Finally, this paper compared and discussed the test results. Findings: The test results show that the friction torque value of vacuum environment horizontal installation condition is the largest at different rotational speeds, and the rotational speed has the most significant influence on the friction torque. Originality/value: The friction torque test system of double-row angular contact ball bearing under vacuum environment was designed and built. The influence rules of vacuum or ordinary pressure environment, horizontal or upright installation mode and different rotational speeds on bearing friction torque were obtained. Peer review: The peer review history for this article is available at: http://dx.doi.org/10.1108/ILT-08-2023-0259 [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]

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]

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]

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]

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]

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]

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]

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]

To elucidate the wind-direction dependence of the rotor performance in closely spaced vertical-axis wind turbines, wind-tunnel experiments were performed at a uniform wind velocity. In the experiments, a pair/trio of three-dimensional printed model turbines with a diameter of D = 50 mm was used. The experiments were performed systematically by applying incremental adjustments to the rotor gap g and rotational direction of each rotor and by changing the wind direction. For tandem layouts, the rotational speed of the downwind rotor is 75–80% that of an isolated rotor, even at g/D = 10. For the average rotational speed of the rotor pair, an origin-symmetrical and a line-symmetrical distribution are observed in the co-rotating and inverse-rotating configurations, respectively, thereby demonstrating the wind-direction dependence for the rotor pair. The inverse-rotating trio configuration yields a higher average rotational speed than the co-rotating trio configuration for any rotor spacing under the ideal bidirectional wind conditions. The maximum average rotational speed should be obtained for a wind direction of θ = 0° in the inverse-rotating trio configuration. The wind-direction dependence of the rotational speeds of the three turbines was explained via flow visualization using a smoke-wire method and velocity field study using two-dimensional computational fluid dynamics. [ABSTRACT FROM AUTHOR]

Rotational autofrettage is one of the new and potential methods for strengthening thick-walled hollow circular disks/cylinders against internal pressure, thermal gradient, and rotational speed in service. The method makes use of the centrifugal force resulting from the high speed rotation of the disk/cylinder to induce plastic deformation at its inner side. On subsequent unloading of the centrifugal force, beneficial residual stresses are set up in the disk/cylinder. In this article, the method of rotational autofrettage employed in the disks is optimized. The rotational autofrettage is treated for an elastic–perfectly plastic axisymmetric disk incorporating Bauschinger effect. The best rotational speed is estimated to accomplish the procedure of rotational autofrettage in the disk such that the maximum stress level induced in the disk is minimized upon loading in service. To minimize the hoop/equivalent stress in the rotationally autofrettaged disk during loading in service, a one-dimensional optimization procedure, internal halving method is used. [ABSTRACT FROM AUTHOR]

This paper focuses on high-speed-operation textile machines with the aim of increasing the rotational speed by operating within the resonance region to vibration amplitudes up to 5g. The native design does not allow keeping the vibration amplitude under 5g, which is a safe operation mode, for revolutions more than 120,000 min−1. The innovative modification of the design was made by the incorporation of polymer composite materials with carbon dust, glass hollow microspheres, and silica sand fillers to the rotor-bearing casing; moreover, through the incorporation of a multilayered foam composite structure and particle damper to the pressure plate of the mechanical machine system. By using the approach of supplementing with high-damping composites, the existing native design can be used, thus avoiding the costly production of new components and subassemblies with modified shapes and dimensions. Twelve possible combinations of mentioned modifications were tested, evaluated and compared with the native design made of steel, as standard structure material in mechanical engineering. The average vibration amplitudes were evaluated in the region before the resonance peak and in the range of the resonance peak, i.e., 120,000–135,000 min−1. Significant vibration amplitude reductions in the range from 30 to 70% of the average vibration amplitude were obtained. The vibration amplitude reduction results were evaluated considering the mass through the amplitude reduction efficiency coefficient. [ABSTRACT FROM AUTHOR]

Welding tools of different designs have been used to join friction stir welding 2-mm-thick Al 7075 sheets, to investigate the effect of the tool geometry on the weld performance. Five cylindrical tools with different pin geometries were manufactured from heat-treatable low alloy steel WNr 1.6582/DIN 34CrNiMo6. Additionally, the effect of the welding speed was considered in the work, with six different speeds ranging from 80 mm/min to 300 mm/min. The weld tool rotational speed was kept constant at 1000 rpm and all other parameters were also kept constant in the experiments. The tensile strength was measured to investigate the mechanical properties of the weld. Results were processed with statistical analysis tools, which showed that the mechanical strength was affected by tool geometry as well as welding speed. The weld tool with the highest pin diameter achieved the highest tensile strength. The welding speed affected the tensile strength differently in the different weld tool geometries studied. The highest weld efficiency reported in the tests is 72.20%, achieved with a cylindrical pin weld tool at 250 mm/min. [ABSTRACT FROM AUTHOR]

Although the energy change field in the centrifugal pump has been investigated under quasi-steady conditions (QSC), equivalent information is not yet known during the rapid starting period (RSP). A centrifugal pump loop system is constructed to investigate the energy change field in the centrifugal pump during RSP. The RSP is selected as a linear rotational speed from 0 rev/min to 2900 rev/min (design rotational speed) and a constant valve opening of 0.569. Results show that the flow rate lags behind the pump head value with the linear increase in rotational speed. The large values of partial derivations of mechanical energy in normal and tangential components are mainly concentrated at the impeller outlet, whose position is insensitive to rotational speed. The region of dominant energy loss is negatively correlated with rotational speed, and an opposite phenomenon is observed in the region of dominant energy increase. With the rotational speed increasing, the mean energy gradient function in the pump impeller and pump volute gradually increases, and the slope of the former is less than that of the latter. After reaching the design rotational speed, the energy change field gradually approaches that under quasi-steady conditions. [ABSTRACT FROM AUTHOR]

This paper deals with rotational moulding. The relationship between mould speed and wall thickness in the upper, middle and lower areas of rotational moulded parts is investigated. Young's modulus of moulded parts is determined via static tensile testing. A static compression test is performed to determine the maximum compressive force causing strain. The test is conducted on the wall of moulded parts, parallel to the main axis of rotation. Also, energy consumption in rotational moulding is investigated for different rotational speeds of the mould. Moulded parts are made of DOWLEX®2629UE linear low-density polyethylene (LLDPE). Experimental results are statistically analysed using STATISTICA 13. Non-parametric statistical tests are used for results analysis. The ANOVA method is employed to determine if there are any significant differences between obtained results. The statistical tests show that the range is much narrower for a speed ratio of 4:1. The narrowest range value is obtained for 12n3 rpm. The highest Young's modulus values are obtained for the parts moulded at 12n3 rpm (1263.33 MPa) and 16n4 rpm (1263.67 MPa). The highest maximum compressive force is obtained for the parts moulded at 12n3 rpm (10 400 N). An analysis of the results demonstrates that the part moulded at 12n3 rpm has the most advantageous properties. For this mould speed, the power consumption amounts to 8.28 kWh. Experimental results and statistical analyses demonstrate that mould speed affects both moulded part quality and energy consumption in the rotational moulding process. [ABSTRACT FROM AUTHOR]

This study aims to determine the performance of a plastic mulch hole making machine and its electrical power requirements. The study begins by providing speed variations on the engine sprocket, calculating the working capacity of the machine, and analysing the power requirements of the electric motor. The results showed that the engine sprocket could perform an optimal rotation speed for punching holes in plastic mulch. Most holes were created in the treatment with a rotational speed of 70 rpm, 16 holes per 5 m of plastic mulch. Overall, the performance of the plastic mulch punching machine has been able to provide fixes in making holes in mulch plastic. Of the three treatments, the speed variations of the plastic mulch punching machine provided perforations with the criteria of perfect and partial perforation. The highest percentage of ideal perforation was found in the treatment with a rotational speed of 29 rpm, 86%, and the lowest was found in the treatment with a rotational speed of 25 rpm, 9.3%. The coefficient of determination between the rotational speed of the machine and the performance of the machine to punch holes in the plastic mulch can be modelled by a polynomial equation. [ABSTRACT FROM AUTHOR]

Background: During the mushroom production process, about one-fifth of the mushroom gets lost. The mushroom residues (MR) are rich in nutrients and can be utilized in diverse applications. Therefore, the goal of this research was to modify a local hammermill to improve the performance of chopping mushroom residues to be efficient used as a by-product. Results: The experiments were conducted on a hammermill without and with six screen diameters, three drum rotational speeds, three feed rates, two average moisture content and two hammer rotation tracks (long–short). Then, chopper experiments were carried out with a focus on a specified size, power consumption and energy required. The findings of using any size screen offered little productivity since after a short time, the chopping MR was built blocks around the drum and blades. But using no screen gives these phenomena disappear. The chopping MR performed well in long track conditions, with a feeding rate of 700 kg/h, a drum speed of 300 rpm and moisture content of 43%. Conclusions: The chopping operation had the best at feed rate of 700 kg/h, drum speed of 3000 rpm and 43% moisture content of which gave the appropriate MWD of 5.54 and 5.32 mm, consumed power of 1114.35 and 1189.125 W and required specific energy of 1.59 and 1.7 kW h/Mg for short and long tracks, respectively, and also largest mean weight diameter under such conditions due to a decrease in the amount of mushroom residues and an increase in their dryness, which increases the fragmentation impact of hammers on mushroom remnants. [ABSTRACT FROM AUTHOR]

The study has investigated the effects of three factors, which were feeding rate, the rotational speed, and the type of used hammers on the some important indicators that could reflecting the performance of the hammer mill. These indicators were: grinding fineness (%), productivity (Kg hr-1 ), and consumed energy (KW). The experiment parameters were organized using a Randomized Complete Design (CRD) with three replications. The results showed that by increasing the feeding rate from 2 cm up to 4 cm, the fineness of grinding, productivity and energy consumed for both crops increased. The results also indicated that by increasing the rotational speed, the productivity and energy consumption increased, while the speed of 2154 rpm achieved the fineness grinding of barley and corn. The results also indicated that the use of conventional hammer led to the highest value concerning the fineness of grinding, and to the highest energy consumptions for both crops, barley, and corn. As for productivity, the manufactured hammer led to the highest values for both crops. However, considering the triple interaction between the studied factors (grinding fineness, productivity, and consumed energy), the manufactured hammer led to the highest value in productivity. [ABSTRACT FROM AUTHOR]

This study addresses the pressing need for eco-friendly potable water production, exploring the promising avenue of solar distillation. To overcome limitations in traditional systems, the author introduces the modified spherical solar still (MSSS), featuring a rotating ball within the design. A comprehensive experimental investigation compared MSSS performance with reference spherical distiller (CSSS) across energetic, exergetic, economic, and environmental (4E) dimensions. Key factors explored included: rotation speeds (0.2–1.2 rpm), wick material on the rotating ball, and thermal storage material (PCM) beneath the ball (desert sand, copper grits, or their mixture). The optimal MSSS configuration was identified: Rotation speed: 0.8 rpm (40 % yield increase), wick material: 57 % distillate enhancement at 0.8 rpm, and combined, these conditions yielded a remarkable 103 % distillate improvement compared to CSSS (7160 vs. 3525 mL/m2.day) and an efficiency of 59.5 %. Exergy efficiency also surpassed CSSS: 4.2 % for MSSS with PCM vs. 3.1 % for CSSS. Notably, the cost per liter of distilled water dropped significantly: $0.024 for MSSS with PCM compared to $0.066 for CSSS. Environmentally, MSSS with PCM saved 27.7 tons of CO 2 annually. Lastly, the enviroeconomic parameter (Z′) rose from 335 for CSSS to 365 for MSSS with PCM. • Study assessed modified spherical solar still (MSSS) with various speeds and PCMs. • MSSS with PCM at 0.75 rpm showed 103 % improvement, 59.5 % efficiency. • Exergy efficiencies at 0.75 rpm with PCM: CSSS 3.1 %, MSSS 4.2 %. • Cost analysis: CSSS $0.066/L, MSSS $0.043/L, MSSS with PCM $0.024/L. [ABSTRACT FROM AUTHOR]

Drilling is one of the most important surgical steps and bone fracture repair. In this step, the temperature may exceed 47 °C and thermal necrosis may occur, which has irreversible consequences. Knowing the amount of heat transferred to the bone and its changes can be effective in recognizing this heat damage and minimizing it. In this research, it was tried to estimate the amount of heat flux entering the bone during the drilling process using the inverse heat transfer method. Drilling tests were performed on cow bone samples and the temperature changes at the hole location were measured using the inverse heat conduction transfer method. The amount of heat input was estimated. The K-type thermocouple is used to measure temperature. The diaphysis fragment of the cow's thigh (middle part), which has a length of about 90 mm and the thickness of the cortical bone in this range is about 8–10 mm, was used. Also, to ease the tests, the beginning and end parts of the fresh femur were cut with a saw. The results show that the maximum heat flux occurs earlier than the maximum temperature. It was observed that the maximum heat flux and the maximum temperature rise with the increase of the rotational speed and the diameter of the tool. As the feed speed rises, first the maximum temperature and maximum heat flux decrease and then increase. By tripling the feed speed, the maximum heat flux decreases by about 20%. The highest percentage rise in temperature and heat flux occurs with a rise in rotational speed, which is around 130–140%. After the rotational speed, increasing the drill diameter increases the temperature up to about 66.7%. The results can be used to prevent thermal necrosis because the maximum heat flux is visible before the occurrence of the maximum temperature. [ABSTRACT FROM AUTHOR]

• Optimised three port, radial-flow gas wave ejector with curved channel is presented. • Designed and established the first radial-flow gas wave ejector platform. • A study on the impact of rotational speed on device performance was conducted, revealing a potential enhancement of 13.25 % in device ejection rate and a corresponding increase in device total efficiency by 11.86 %. • Through simulation validation, it is observed that the flow losses of the equipment exhibit a trend of initial reduction followed by subsequent increase as the rotational speed is elevated. The gas wave ejector (GWE) is a device that enables energy transfer between gases at different pressures through pressure waves. We conduct an experimental and simulation study on a novel radial-flow GWE, named DUT-R1, designed to harness centrifugal force to enhance mass and energy transfer efficiencies. Considering the significant influence of rotational speed (n) on the pressure waves and flow losses, we examine the relationship between the n of the DUT-R1 and both its ejection rate (ξ) and total efficiency (η T). Experimental data demonstrate that the GWE can attain the highest ξ and η T at an optimal designed rotational velocity (n d) when the pressure ports remain fixed. Simulations suggest that the primary cause can be attributed to the disruption of the ideal wave system. And when the equipment is equipped with ports matched to the n d , a consistent increase ξ is observed as the n d increases from 2000 r/min to 4000 r/min, resulting in a maximum improvement of 13.25 %. The simulation results demonstrate that increasing n enhances the suction capacity of the equipment through the inputting of shaft power (P). However, η T initially increases and then decreases as the n d increases, with a maximum improvement of 11.86 %. The simulation provides an explanation for the observed variations in η T during the experimental investigation by illustrating that flow losses initially decrease and then subsequently increase with an increasing value of n. [ABSTRACT FROM AUTHOR]

The hydrogen circulating pump is an essential component of hydrogen fuel cell systems. It plays a vital role in improving hydrogen utilization efficiency and optimizing hydrothermal control capabilities. Due to its compact design, high efficiency, and outstanding low-temperature adaption performance, the lobe hydrogen circulating pump has excellent potential for hydrogen recirculation in fuel cell vehicles (FCVs). This paper investigated the internal flow characteristics of a lobe hydrogen pump for FCV under different rotational speeds by experiments and computational fluid dynamics (CFD). Moreover, the lobe rotor domain was calculated using the dynamic mesh method. The effects of different rotating speeds on transient pressure pulsation, exhaust flow rate, external noise, and vibration were studied. The result reveals that the volumetric efficiency improves with the increased lobe rotor speed when the pressure ratio remains constant. The vibration acceleration level (VAL) and the external noise also increase. The vibration is most significant at the pump casing outlet and tends to decrease as the frequency increases. The sound pressure level spectrum has a discrete character in the low-frequency band, with peaks mainly concentrated at the rotating fundamental frequency and harmonics. The middle and high frequency bands have prominent broadband characteristics, and the energy is relatively concentrated. [Display omitted] • 3D simulation method for hydrogen pump based on the dynamic mesh was presented. • The effect of rotational speeds on unsteady characteristics was obtained. • The leakage characteristics of rotor-rotor and rotor-casing clearances were revealed. • The features of vibration and noise at different rotational speeds were revealed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

One of the most important machines in the olive oil extraction line is the horizontal three-phase centrifugal separator machine or Tricanter. The purpose of this paper is to evaluate the machine designed on the basis of Tricanter and to evaluate the quality of extracted olive oil. For this purpose, four different olive cultivars from Gilan Province in Iran were used. In this research the rotational speed of the Tricanter machine was tested at three levels of 2 500, 3 000, and 3 500 rpm and the content of water added to olive paste was used at three levels of 10, 20, and 30% of the paste mass. Peroxide value (PV) and percentage of acidity were measured for oil extracted from all four olive cultivars. The results of the analysis of variance (ANOVA) test showed that rotational speed and the content of added water had an effect on the acidity and PV for all samples of olive cultivars. The measured values showed that the best speed for the Tricanter machine is 3 500 rpm. At this rotational speed, the peroxide and acidity values are lower than the standard values. [ABSTRACT FROM AUTHOR]

All-hydraulic drill has been widely employed in core drilling recently, which results in larger Weight on Bit (WOB) and higher rotational speed to diamond bit. Thus, new requirements of diamond bit abrasiveness are needed to satisfy the severe challenges. To investigate the effects of WOB and rotational speed on the friction and wear properties of diamond bit matrix, an experimental scheme with 2 factors and 4 levels was designed to carry on the friction and wear test, and two kinds of Fe based diamond bit matrix formula systems, i.e. elemental metal powders and pre-alloyed powders were considered. The samples were manufactured by hot-pressing. Test results indicate that the abrasion loss of the Fe based samples increase with the raise of WOB and rotational speed, while the WOB has a bigger significance. The wear mechanism of the bit matrix is dominated by adhesive wear under smaller WOB and lower rotational speed, while abrasive were will become more and more important with the increase of WOB. Besides, samples from the pre-alloyed powders formula system have better performance than the ones from elemental system, the abrasion can be reduced by up to 15.52%, when under the same test conditions. [ABSTRACT FROM AUTHOR]

Friction stir welding equipment was used to weld 3 mm thick 6082 aluminum alloy and T2 copper, through metallurgical microscopy, hardness testings tensile testing, etc.explore the impacts of rotational speed on the organization and mechanical properties of welded joints. The results show that: Intermittent defects always exist at the interface of the joint, alternating distribution of aluminum and copper, and uniform mixing of the two materials; The microhardness distribution of the joint shows that the highest value appears in the weld core area with hardness of 210 HV, aluminum and copper side heat affected zone hardness have decreased, the lowest value for the aluminum side heat affected zone of about 60 H V; with the increase in speedy the tensile strength increases first and then decreases, when the spindle speed of 1 000 r/min, welding speed of 50 mm/min, the optimal weld forming effect, the tensile strength can reach 255 MPa, the fracture shape becomes more uniform with the increase of rotational speed, and the toughness nest increases, showing a stratified distribution. The fracture location is the aluminum copper bond, and the crack extends along the interface defect, showing mixed brittle ductile fracture at low speed and ductile fracture at high speed. [ABSTRACT FROM AUTHOR]

The object of research is granulation of mineral fertilizers by the rolling method. One of the most problematic places is the uncertainty of the conditions of the temperature regime of granulation. The paper considers the technology for obtaining enlarged urea granules of prolonged action. It is indicated that an increase in the diameter of the granules to 7–10 mm increases the efficiency of the use of mineral fertilizers by the consumer. It is proposed to obtain large carbamide granules by rolling in a plate granulator. It is indicated that the setting of the optimal operating parameters of the tray granulator is an important factor in the efficient operation of the equipment. A scheme of a pilot plant for granulating mineral fertilizers is presented, a methodology for conducting experimental studies and design parameters of a plate granulator are described. It is indicated that in the process of experimental studies, the design parameters changed: the tilt angle of the plate, the height of the side and the frequency of rotation of the plate, the angle of opening of the spray jet by the hydraulic nozzle. In the process of research, the influence of regime and technological parameters, namely, the temperature of the layer on the plate is studied. As a result of experimental studies, the optimal ranges of design and regime-technological parameters for obtaining enlarged carbamide granules in a plate granulator were revealed. The influence of the location of the nozzle for spraying the melt on the layer relative to the plane of the plate is shown, which results in the particle size distribution of the granular product. It is indicated that a higher content of the commercial fraction in the finished product is observed when the layer in the left sector of the upper part of the plate is irrigated by the rising melt. A technique for determining the static strength of the obtained carbamide granules is given. A calculation equation for determining the static strength of a granule is presented. A diagram of a laboratory device for determining the static strength of granules is presented, which made it possible to determine the values of the static strength of granules for individual fractions, namely: for coarse, fine and commercial fractions. It is shown that the obtained values correlate well with standardized indicators. [ABSTRACT FROM AUTHOR]

To comply with the government's sports policy, schools at all levels and localities have systematically and actively promoted the game of table tennis, which has become one of the most popular sports in Taiwan. Loop ball is a current table tennis practice method that can improve table tennis skills. Players who master the techniques associated with loop ball can improve their fine scoring skills in table tennis. Therefore, the main purpose of this study was to establish a model for quantifying the flight speed and trajectory of the looping ball. Methods: A closed-form set of sixvariable nonlinear control equations was established to estimate the movement of a table tennis ball. Numerical calculations were conducted using the high-precision Runge-Kutta-Feiberg method, and differences between trajectories and key kinematic properties were discussed. Results: The results of the study found that side-spin drive generates more lateral Magnus force due to the lateral rotation rate than the other two loops. The lateral deviation of the landing point can reach 0.21 meters, with an offset angle of approximately 8.07°. A ball with a faster initial rotation of the sphere that was hit from a more outside contact point will fall faster with a drop point closer to the end of the table, increasing the amount of side deviation. Conclusion: This study quantitatively compared the degree of lateral deviation and drop in response to various angular side-spin rates relative to the initial position of the ball at the point of contact. In the future, this model can also be applied to calculations of table tennis ball movement characteristics under various conditions or circumstances. [ABSTRACT FROM AUTHOR]

The surface modification process with specific characteristics is an important subject to achieve the highperformance contact behavior of pair surfaces. (Low frequency) vibration-assisted machining is one of the interesting processes which fabricates large-scale textures. This process can fabricate textures with various geometries in regular periodic distances. Current research develops a novel configuration that employs low-frequency vibrations during face turning to fabricate various textures on the surface of Al-7075 flexibly and efficiently. Process characteristics (rotational speed and feed) are controlled to adjust texture geometry. Results showed that the dimple length has a direct relation to the rotational speed. However, dimples number presented a reverse relation to the feed and rotational speed. Reducing rotational speed from 90 to 31.5 rpm could decrease the dimple length up to 73% and increase the dimples number up to 68%. Texture density was evaluated according to surface parameters of Sdr and Sds. Contrasting effects of mentioned parameters on the wettability achieved the minimum contact angle in the optimum rotational speed of 63 rpm. In the same procedure and the case of the friction coefficient, the rotational speed of 45 rpm was determined as the optimum condition with the smallest friction coefficient. The optimum condition has been determined for the developed configuration and assumed constant and variable (specific variation interval) parameters. [ABSTRACT FROM AUTHOR]

During dissimilar friction stir welding (FSW) of Al-Mg2Si metal matrix composite and AA6061 aluminum alloy, the temperature field and heat generation were investigated using a 3-dimensional computational fluid dynamics (CFD) model and FLUENT software. The simulations were conducted for rotational speeds of 720, 920, and 1120 rpm. The welding experiments were carried out to validate the simulation results. About 70% of the heat is generated at the interface between the shoulder and the workpiece. The maximum temperature is predicted on the advancing side (AS). The difference between the peak temperatures on the AS and the retreating side (RS) is about 115 K. The effect of the rotational speed on the peak temperature is significant. The temperature distribution in the cross sections is asymmetric, which originates from different material velocities on the AS and RS. The peak temperature on the RS develops under the top surface, while the peak temperature on the AS develops on the surface. [ABSTRACT FROM AUTHOR]

The aim of this study was to predict the temperatures on all surfaces of threedimensional 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. [ABSTRACT FROM AUTHOR]

To minimize the energy consumption of contra-rotating propellers (CRPs), the optimal matched rotational speeds of the forward propeller (FP) and rear propeller (RP) of CRP are investigated based on the potential-based panel method. The optimal matching problem of a set of CRP405 is investigated. The open-water hydrodynamic performances of CRP405 with the FP and RP having the same rotational speed are calculated and the method is validated. The hydrodynamic characteristics of CRP405 with changing FP and RP rotational speeds are investigated. The cubic spline interpolation method is used to determine the equal thrust line at which CRP405 generates the target thrust while keeping the inflow velocity constant. A series of equal thrust points on the equal thrust line is selected for the analysis of the delivered power. The rotational speeds of the FP and RP corresponding to the minimal delivered power are the optimal matched rotational speeds of CRP405. The optimal matching calculations are carried out at different inflow velocities. The results show that, under the condition of a low inflow velocity, properly increasing the rotational speed of the FP and decreasing the rotational speed of the RP are the most direct and efficient ways to reduce the energy consumption and avoid the negative effect of the net torque of the CRP on the transverse stability. [ABSTRACT FROM AUTHOR]

Small-scale ducted fans can be used to generate the necessary force and moment for propulsion in many applications. In the present work, the aerodynamic performance of a ducted fans system (DFS), which consists two distinct counter-rotating ducted fans, is analyzed numerically by considering the influence of different geometrical parameters that include rotational speed, eccentricity, and the distance between the two fans. The results reveal that the force and moment in the axial direction are orders of magnitude higher than those in the other two directions under typical conditions. The aerodynamic performance of the DFS shows only minor vibrations for dimensionless rotational speed N below 1 which corresponds to the critical physical rotational speed of 2.104 rpm. Moreover, the force and moment increase dramatically for higher N, following the typical relationship between rotational speed and force for rotor systems. The eccentricity contributes to significant increase in magnitudes on both force and moment in all three directions, whereas the distance between the twin fans exhibits little impact. The numerical simulations suggest that the exploitation of eccentricity is the most efficient approach to control the total output of force and moment of the DFS within the investigated range of geometrical parameters. [ABSTRACT FROM AUTHOR]

A waterjet propulsion device is a new type of propulsion system whose inlet passage affects the performance of the entire device. To study the influence of the inlet passage with an inclined pipe section (IPS) on the hydrodynamic characteristics of the device, a numerical method was used to determine the influences of IPS's length L and rotational speed n on hydraulic performance and thrust characteristics. Results show that the head H of the device increases significantly from 3.29 m to 12.64 m as rotational speed n increases (700 r/min < n < 1300 r/min). Moreover, efficiency η increases from 61.37 % to 64.75 % and then decreases to 60.99 %. L exerts minimal effect on η, which reaches its maximum value when n = 900 r/min and L = 1.12 D (D is the outlet diameter of the inlet passage). Device thrust F gradually increases with an increase in n, and the increase rate continues to rise, while L has minimal effect on F. The results provide a reference for optimizing the inlet passage of a waterjet propulsion device. [ABSTRACT FROM AUTHOR]

Solar desalination is a viable solution to provide drinkable water to remote areas using free energy, basic technologies, and a healthy environment. The challenge of low daily productivity inspires the researchers to find different approaches to increase the thermal performance of the distillation methods with minimized cost. This paper proposed a new distillation concept using solar stills. An innovative designed vertical distiller with two rotating discs was investigated. Besides, the performance of modified single-stage vertical distiller (MSSVD) and modified double stage vertical distiller (MDSVD) were studied and compared with that of the conventional tilted distiller (CTD) and conventional vertical distiller (CVD). Reaching the optimal depth of basin water and augmenting the evaporation and condensation rates of the vertical distiller were targeted. Moreover, different rotational speeds (from 0.125 rpm to 2.5 rpm) were investigated to indicate the optimum disc speed that provide the highest productivity. Experimental results indicated that the proposed vertical solar still provided higher freshwater productivity than the CTD. In addition, using rotating discs significantly improved the distillers’ yield. Also, the best distiller performance was achieved at 1.5 rpm. Moreover, the daily freshwater output was 2300 mL/m2.day for CTD, 2730 mL/m2.day for CVD, 10350 mL/m2.day for MSSVD, and 16500 mL/m2.day for MDSVD. So, the yield of MSSVD and MDSVD was improved by 350% and 617.4%, respectively over that of CTD. The maximum thermal efficiency for MSSVD and MDSVD was 48.4% and 77.2%, respectively. Finally, the average distillate cost was 0.027, 0.051, 0.018, and 0.019 $/L for CTD, CVD, MSSVD, and MDSVD, respectively. [ABSTRACT FROM AUTHOR]

For a direct dry cooling system, the turbine back pressure fluctuates with the meteorological conditions. Moreover, the operation of axial flow fans plays an important role in the cooling performance of air‐cooled condensers (ACC). It is of significant use to study the operation strategies of axial flow fans under various ambient conditions. Based on typical 2 × 660MWdirect dry cooling power generating units, the ACC model coupled with the turbine thermodynamic characteristics is developed, by which the thermo‐flow performances of the ACC are predicted in the dominant wind direction, and then the standard coal consumption is calculated. The results show that the increased ambient temperature and wind speed, or the reduced fan rotational speed leads to the high turbine back pressure. At the low ambient temperature and wind speed, the standard coal consumption rate of the unit can be reduced by reducing the speed of axial flow fans appropriately, with the maximum drop in coal consumption rate reached 0.734 g/(kWh) when the ambient temperature is 10°C without wind. If the wind speed exceeds 12 m/s or the ambient temperature reaches 25°C, 110% of the rated fan rotational speed is recommended. [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]

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 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]

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]

Inertia friction welding (IFW) is a solid‐state welding technology that avoids defects associated with molten weld processes; however, this process has rarely been used to weld ultrahigh‐strength steel (UHSS). Herein, 32CrMnSi2Ni6MoV UHSS is joined successfully via IFW. The mechanical properties after welding at different rotational speeds and the microstructure at 2800 rpm are studied in detail. The temperature distributions in the peripheral and central areas are modeled according to the temperature at the weld zone. The microstructural transformation is analyzed for different temperature intervals, and the microstructural characteristics of each interval correspond to the actual microstructure of the welded joint according to the temperature distribution model. High‐strength martensite forms at the weld zone, and the thermomechanical‐affected zone (TMAZ) in the peripheral region is divided into phase transformation zone, partial recrystallization zone, and plastic deformation zone, whereas the TMAZ in the central region includes only the partial recrystallization and pure plastic deformation zones. This difference is due to the higher frictional heat caused by the higher peripheral linear velocity during rotation. A tensile test shows that fracture occurs in the base metal (BM) region, and the yield strength, tensile strength, and elongation are 805 MPa, 1064 MPa, and 13.88%, respectively. [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]

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]