Rotations Per Minute Research Articles

Acoustically-actuated bubble-powered rotational micro-propellers

Bubble-powered acoustic microsystems span a plethora of applications that range from lab-on-chip diagnostic platforms to targeted interventions as microrobots. Numerous studies strategize this bubble-powered mechanism to generate autonomous self-propulsion of microrobots in response to high frequency sound waves. Herein, we present two micro-propeller designs which contain an axis-symmetric distribution of entrapped bubbles that vibrate to induce fast rotational motion. Our micro-propellers are synthesized using 3D Direct Laser Writing and chemically-functionalized to selectively trap air bubbles at their micro-cavities which function as propulsion units. These rotational acoustic micro-propellers offer a dual advantage of being used as mobile microfluidic mixers, and as autonomous microrobots for targeted manipulation. With regards to targeted manipulation, we demonstrate magneto-acoustic actuation of our first propeller design that can be steered to a desired location to perform rotational motion. Furthermore, our second propeller design comprises of a helical arrangement of bubble-filled cavities which makes it suitable for spatial micro-mixing. Our acoustic propellers can reach speeds of up to 400 RPM (rotations per minute) without requiring any direct contact with a vibrating substrate in contrast to the state-of-the-art rotary acoustic microsystems.

Role of Mg2+ substitution on viscosity and thermal conductivity of nickel ferrite based magnetic fluids

The present investigation shows the viscosity and thermal conductivity of Mg2+ substituted nickel ferrite based magnetic fluids of different chemical compositions (Ni1-xMgxFe2O4). The nanoparticles were synthesized using a simple and cost-effective co-precipitation method. The XRD result shows the formation of a cubic spinel structure. SEM analysis confirmed the size of the nanoparticles ranges between 1 µm and 500 nm. The Experimental results show that the viscosity of magnetic fluids of two different volume fractions decreases for the rise in temperature and for the increase in rotations per minute (RPM). The results on thermal conductivity of two different volume fractions of Ni1-xMgxFe2O4 based magnetic fluids exhibit enhanced thermal conductivity than the carrier fluid (transformer oil). The thermal conductivity results were compared with Maxwell’s theoretical prediction and experimental models for confirmation.

Design ofasoft sensing technique for measuring pitch and yaw angular positions foraTwinRotor MIMOSystem.

This paper presentsa soft sensor design technique for estimation of pitch and yaw angular positions of a Twin Rotor MIMO System (TRMS).The objective of the proposed workwas to calculate the value of pitch and yaw angular positions using a stochastic estimation technique. Methods:Measurements from optical sensorswereused to measure fan blade rotationsper minute(RPM). The Kalman filter,which is a stochastic estimator,was used in the proposed system and its resultswere compared with those oftheLuenbergerobserver and neural network. The TwinRotor MIMOSystem is a nonlinear system with significant cross coupling between its rotors. Results:The estimatorswere designed for the decoupled system andwere applied in real life to the coupled TRMS. The convergence of estimation to the actual valueswas checked on a practical setup. The Kalman filter estimatorswere evaluated for various inputs and disturbances, and the resultswere corroborated in real time. Conclusion:From the proposed work itwas seen thattheKalman filterhadatleastIntegral Absolute Error(IAE),Integral Square Error(ISE),Integral Time Absolute Error(ITAE)as compared totheneural network andtheLuenbergerbased observer.

Cyclic fatigue resistance of twisted files, Hyflex cm, Hyflex EDM and Edgefile X3 after immersion in sodium hypochlorite

Aim and Objective: This investigation analyzed the cyclic fatigue resistance (CFR) of three controlled memory (CM) of (twisted files, Hyflex cm, Hyflex EDM and Edgefile X3) after immersion in sodium hypochlorite. Material and Method: 160 files of a similar brand were arbitrarily allocated to four groups (n =40) and submitted to the immersion protocol: Group 1: no immersion (as control), Group 2: 3 minute in 2.5% NaOCl at room temperature, Group 3: 32.5 minutes in 2. 5% NaOCl at 121ºC and one cycle of autoclave sterilization, Group 4: To five cycles of the same test protocols as in Group 3. Cyclic fatigue test was performed on rotating/reciprocating all instruments. The number of cycles to failure (NCF) for every instrument was calculated by multiplying the quantity of rotations per minute (RPM) multiplied by total time taken for the instrument to fracture (minutes).Result: EdgeFile X3 files showed most increased cyclic fatigue resistance, followed by Hyflex EDM files, Hyflex CM files and least resistance displayed by twisted files. Instruments immersed in NaOCl solution after five cycles of autoclave sterilization show increase in cyclic fatigue resistance for heat-treated instruments in comparison with the control group.Conclusions: This study show that fracture resistance to cyclic fatigue was the most increased for the EdgeFile X3 group followed by Hyflex EDM, Hyflex CM and least for Twisted File group and instruments undergoing dynamic immersion in NaOCl solution for long time and to five cycles of autoclave sterilization increase CFR.

Design of CDI (Capasitive Discharge Ignition) and Motor Spark Plugs Test Kits

The Ignition on a motorcycle is an electrical system that produces sparks in the combustion chamber. If there is a mass of ferromagnetic material moving closer to the sensor, then the pulser will generate an electric current. Greater the electric current it generates. With the working principle of such a pulser, it can be used as a rotation sensor and sent to the ignition coil to produce a higher voltage which will produce sparks at the end of the spark plug electrode. The perfection of the system affects the motor work system. A good CDI condition will make it easier to increase the RPM (Rotations Per Minute) and when the spark plugs are in good condition, the motorbike's performance is getting optimal. There can be a useful tool for analyzing the damage to the CDI and the spark on the spark plug by integrating the electronic system in the motor ignition system. An electronic circuit that connects the motorcycle's ignition system through the output of the pulser circuit signal, which triggers the CDI input instead of the pulse magnet. Because the CDI and motor spark plugs are one of the main components that play an important role in the performance of the combustion motor. So that the electrical system can work without using mechanics and can be used as a tool to be able to analyze CDI damage and motor spark plug performance because CDI and spark plugs are some of the main components that play an important role in combustion motor performance. The result is that the tool can test CDI and motor spark plugs efficiently after which it can conclude the damage and can distinguish the characteristics of the CDI and the motor plugs.

Prediction of product roughness, profile, and roundness using machine learning techniques for a hard turning process

High product quality is one of key demands of customers in the field of manufacturing such as computer numerical control (CNC) machining. Quality monitoring and prediction is of great importance to assure high-quality or zero defect production. In this work, we consider roughness parameter Ra, profile deviation Pt and roundness deviation RONt of the machined products by a lathe. Intrinsically, these three parameters are much related to the machine spindle parameters of preload, temperature, and rotations per minute (RPMs), while in this paper, spindle vibration and cutting force are taken as inputs and used to predict the three quality parameters. Power spectral density (PSD) based feature extraction, the method to generate compact and well-correlated features, is proposed in details in this paper. Using the efficient features, neural network based machine learning technique turns out to be able to result in high prediction accuracy with R2 score of 0.92 for roughness, 0.86 for profile, and 0.95 for roundness.

Automatic Voltage Regulator as a Voltage Control in 1 Phase Axial Generator System

A constant output voltage on a generator is very important to produce the expected power supply. Changes in the output voltage of a generator are influenced by various disturbing factors, one of which is load and Rotations Per Minute (RPM) which are not always constant. Therefore we need a special regulator equipment to keep the generator output voltage constant. The problem of voltage instability during load changes must be overcome to keep the voltage constant, so that equipment is needed that can control the voltage stability. This tool is the Automatic Voltage Regulator (AVR). The purpose of this study is to design a voltage control device in a single phase axial generator system. The research method used consists of 3 stages, namely: 1). Design and design of tools, 2). Stages of making tools, 3). Stages of testing the tool. The results of the research were obtained when an axial generator with an inner air gap of 0.4 cm, outer 0.5 cm and rpm 2589. The output voltage of the generator began to decrease significantly until it reached -70 volts and rpm also decreased to -200. In contrast, when the generator is operated using the AVR, the reduction only reaches -30 volts. However, when the generator is operated with AVR, the decrease in rpm is greater until it reaches -220.

Micellar-enhanced ultrafiltration (MEUF) for removal of rhodamine B (RhB) from aqueous system

Micellar-enhanced ultrafiltration (MEUF) has proved itself to be a potentially attractive tool to remove contaminants from waste water. The reported study is particularly focused on the interaction and removal of cationic dye, Rhodamine B (RhB), using micellar solution of anionic surfactants, that is, Sodium dodecyl sulfate (SDS) and Sodium Oleate (SO). Dye removal efficiency has been assessed in terms of rejection percentage and permeate flux, using cellulose membrane of 10,000 molecular weight cutoff (MWCO). The effects of various factors, that is, ionic strength, concentration of surfactants, concentration of electrolyte, pH, operating pressure and rotations per minute (RPM) has been observed. It has been concluded that the maximum rejection of dye has been observed using micellar media of SDS. Overall, it has been observed that the rejection coefficient of dye is higher at higher concentration of surfactants and electrolyte and at lower values of pH, RPM and transmembrane pressure.

Buildability and Mechanical Properties of 3D Printed Concrete.

Recently, 3D concrete printing has progressed rapidly in the construction industry. However, this technique still contains several factors that influence the buildability and mechanical properties of the printed concrete. Therefore, this study investigated the effects of the nozzle speed, the interlayer interval time, the rotations per minute (RPMs) of the screw in the 3D printing device, and the presence of lateral supports on the buildability of 3D concrete printing. In addition, this paper presents the results of the mechanical properties, including the compressive, splitting tensile, and flexural tensile strengths of 3D printed concrete. The buildability of 3D printed structures was improved with an extended interlayer interval time of up to 300 s. The printing processes were interrupted because of tearing of concrete filaments, which was related to excessive RPMs of the mixing screw. The test results also showed that a lateral support with a wide contact surface could improve the resistance to buckling failure for 3D printed structures. The test results of the mechanical properties of the 3D printed concrete specimens indicated that the compressive, splitting tensile, and flexural tensile strengths significantly depended on the bonding behavior at the interlayers of the printed specimens. In addition, although metal laths were expected to improve the tensile strength of the printed specimens, they adversely affected the tensile performance due to weak bonding between the reinforcements and concrete filaments.

Coriolis Time Intervals in prediction of outcome of Motion Sickness Desensitization Therapy

Introduction: Motion sickness is a common problem faced during flying training. Aircrew with persistent motion sickness require motion sickness desensitization. Although many aircrew benefit from the motion sickness desensitization therapy (MSDT), a significant number of individuals fail to complete the desensitization program. Early prediction of desensitization program outcome would identify non-responders and help in increasing the efficiency of MSDT. Material and Methods: A retrospective survey of candidates who underwent MSDT at the Institute of Aerospace Medicine between 2009 and 2019 was done. Coriolis time interval (CTI) values of 28 candidates could be retrieved. Mean CTI values of the successful and unsuccessful candidates at 5 rotations per minute (RPM) were compared. Statistical analysis was done using independent t-test, binary logistic regression, and a receiver operator characteristics (ROC) analysis. Results: The unsuccessful group candidates (M = 14.3, SD = 8.7 s) had significantly higher mean CTI values at 5 RPM than the successful group candidates (M = 6, SD =2.3 s); t (15.09) = −3.43, P = 0.04. Logistic regression indicated that there was a significant association between the CTI values and MSDT outcome, Chi-square (1, n = 26) =12.73, P ≤ 0.001. ROC analysis revealed a statistically significant curve with a good predictive cutoff value for CTI to identify non-responders. Conclusion: Results indicated that CTI values are reliable indicators in predicting the outcome of MSDT. Inclusion of other parameters, both physiological and psychological, that have a good correlation with motion sickness may give us better predictive models. Such predictors will also help in better understanding of the pathophysiology of motion sickness and in formulating improved treatment modalities.

Effect of Surgical Instrumentation Variables on the Osseointegration of Narrow- and Wide-Diameter Short Implants

The aim of the present study was to systematically analyze how a multifactorial surgical instrumentation approach affects osseointegration on both narrow-diameter and wide-diameter short implants. Twelve skeletally mature female sheep were used in the study along with 144 plateau-root-form healing chamber titanium (Ti-6Al-4V) implants (Bicon LLC, Boston, MA), evenly distributed between narrow (3.5mm) and wide (6.0mm) diameters. The presence or the absence of irrigation, different drilling speeds, and 2 time points quantifying bone-implant contact (BIC) and bone area fraction occupancy (BAFO) to evaluate the osteogenic parameters around the implants. There were no signs of inflammation, infection, or failure of the implants observed at either healing period. The narrow 3.5-mm implant, at 6weeks, yielded significant differences in terms of BIC at a drilling speed of 50 rotations per minute (RPM), with higher values of the samples using irrigation (30.6±6.1%) compared with those without (19.7±6.1%). No statistical differences were detected for 500 and 1,000 RPM with or without irrigation. The wide 6-mm diameter implant showed differences with respect to drilling speed, 500 and 1,000RPM, with higher values associated with samples subjected to irrigation. BAFO results, for both diameters, only detected statistical differences between the 2 times (3vs 6 weeks); no statistical differences were detected when evaluating as a function of time, drilling speed, and irrigation. Surgical instrumentation variables (ie, drilling speed [RPM] and irrigation) yielded to be more of an effect for BIC at longer healing time (6 weeks) for the wider implants. Furthermore, deploying narrow or wide plateau-root-form implants, where conditions allow, has shown to be a safe alternative, considering the high BIC and BAFO values observed, independent of irrigation.

Generating pseudo density log from drilling and logging-while-drilling data using extreme gradient boosting (XGBoost)

Density log data is one of the key physical attributes used for reservoir characterization by quantifying and qualifying lithological attributes in a wellbore. The density log is most often acquired by geophysical wireline logging techniques after drilling. However, wireline logging can be difficult to execute in highly deviated wells and alternative data acquisition such as logging-while-drilling (LWD) can be very costly. This paper describes the process of using instantaneous drilling attributes together with a machine learning algorithm, extreme gradient boosting (XGBoost), to generate a pseudo density log. The mean absolute error (MAE) and root mean square error (RMSE) are used as the evaluation metrics. Case studies are performed using data from six coalbed methane (or coal seam gas) wells in the Surat Basin, Australia. The inputs include drilling data [weight on bit (WOB), rotations per minute (RPM), torque, true vertical depth (TVD) and rate of penetration (ROP)] and LWD data (i.e., natural gamma ray and hole diameter). The MAE of pseudo density log for most wells is between 0.08 and 0.11 g/cc (except Well 4 is 0.16 g/cc), which results in an average error rate less than 5%. It is found that TVD, gamma ray, ROP, and hole diameter are four most important features. Further experiment shows that the model with these four important features has almost the same performance as the model with all features. The proposed machine learning methodology can assist petroleum engineers and geologists in reservoir characterization by generating pseudo density logs from ongoing LWD and drilling data in real time. It can potentially mitigate the need to run wireline logging tools after drilling or costly LWD techniques whilst drilling.

Klebsiella pneumoniae-A Useful Pathogenic Strain for Biotechnological Purposes: Diols Biosynthesis under Controlled and Uncontrolled pH Levels.

Despite being a well-known human pathogen, Klebsiella pneumoniae plays a significant role in the biotechnology field, being considered as a microbial cell factory in terms of valuable chemical biosynthesis. In this work, Klebsiella pneumoniae DSMZ 2026 was investigated for its potential to biosynthesize 1,3-propanediol (PDO) and 2,3-butanediol (BDO) during batch fermentation under controlled and uncontrolled pH levels. The bacterial strain was cultivated at a bioreactor level, and it was inoculated in 2 L of specific mineral broth containing 50 g/L of glycerol as the main carbon source. The process was conducted under anaerobic conditions at 37 °C and 180 RPM (rotations per minute) for 24 h. The effect of pH oscillation on the biosynthesis of PDO and BDO was investigated. Samples were taken every 3 h and specific tests were performed: pH measurement, main substrate consumption, PDO and BDO production. The cell morphology was analyzed on both solid and liquid media. After 24 h of cultivation, the maximum concentrations of PDO and BDO were 28.63 ± 2.20 g/L and 18.10 ± 1.10 g/L when the pH value was maintained at 7. Decreased concentrations of PDO and BDO were achieved (11.08 ± 0.14 g/L and 7.35 ± 0.00 g/L, respectively) when the pH level was not maintained at constant values. Moreover, it was identified the presence of other metabolites (lactic, citric, and succinic acids) in the cultivation media at the beginning of the process, after 12 h and 24 h of cultivation.

Bipolar Cu/HfO2/p++ Si Memristors by Sol-Gel Spin Coating Method and Their Application to Environmental Sensing

In this paper, the memristive switching behavior of Cu/ HfO2/p++ Si devices fabricated by an organic-polymer-assisted sol-gel spin-coating method, coupled with post-annealing and shadow-mask metal sputtering steps, is examined. HfO2 layers of about 190 nm and 80 nm, are established using cost-effective spin-coating method, at deposition speeds of 2000 and 4000 rotations per minute (RPM), respectively. For two types of devices, the memristive characteristics (Von, Ion, and Vreset) and device-to-device electrical repeatability are primarily discussed in correlation with the oxide layer uniformity and thickness. The devices presented in this work exhibit an electroforming free and bipolar memory-resistive switching behavior that is typical of an Electrochemical Metallization (ECM) I-V fingerprint. The sample devices deposited at 4000 RPM generally show less variation in electrical performance parameters compared to those prepared at halved spin-coating speed. Typically, the samples prepared at 4000 RPM (n = 8) display a mean switching voltage Von of 3.0 V (±0.3) and mean reset voltage Vreset of −1.1 V (±0.5) over 50 consecutive sweep cycles. These devices exhibit a large Roff/Ron window (up to 104), and sufficient electrical endurance and retention properties to be further examined for radiation sensing. As they exhibit less statistical uncertainty compared to the samples fabricated at 2000 RPM, the devices prepared at 4000 RPM are tested for the detection of soft gamma rays (emitted from low-activity Cs-137 and Am-241 radioactive sources), by assessing the variation in the on-state resistance value upon exposure. The analysis of the probability distributions of the logarithmic Ron values measured over repeated ON-OFF cycles, before, during and after exposing the devices to radiation, demonstrate a statistical difference. These results pave the way for the fabrication and development of cost-effective soft-gamma ray detectors.

Tolerable Acclimation to the Cross-Coupled Illusion through a 10-day, Incremental, Personalized Protocol

BACKGROUNDArtificial gravity (AG) has the potential to provide a comprehensive countermeasure mitigating deleterious effects of microgravity. However, the cross-coupled "Coriolis" illusion has prevented using a more feasible and less costly short-radius centrifuge, as compared to large, slowly spinning systems.OBJECTIVEWe assessed tolerability of a personalized, incremental protocol to acclimate humans to the cross-coupled illusion, enabling faster spin rates.METHODSTen subjects were exposed to the illusion by performing roll head tilts while seated upright and spun about an Earth-vertical axis. The spin rate was incremented when head tilts did not subjectively elicit the illusion. Subjects completed one 25-minute session on each of 10 days.RESULTSThe spin rate at which subjects felt no cross-coupled illusion increased in all subjects from an average of 1.8 rotations per minute (RPM) (SD: ±0.9) at the beginning of the protocol to 17.7 RPM (SD: ±9.1) at the end. For off-axis centrifugation producing 1G at the rider's feet, this corresponds to a reduction in the required centrifuge diameter from 552.2 to 5.7 meters. Subjects reported no more than slight motion sickness.CONCLUSIONSAcclimation to the cross-coupled illusion, such as that accomplished here, is critical for feasibility of short-radius centrifugation for AG implementation.

Tolerable acclimation to the cross-coupled illusion through a 10-day, incremental, personalized protocol.

BACKGROUNDArtificial gravity (AG) has the potential to provide a comprehensive countermeasure mitigating deleterious effects of microgravity. However, the cross-coupled "Coriolis" illusion has prevented using a more feasible and less costly short-radius centrifuge, as compared to large, slowly spinning systems.OBJECTIVEWe assessed tolerability of a personalized, incremental protocol to acclimate humans to the cross-coupled illusion, enabling faster spin rates.METHODSTen subjects were exposed to the illusion by performing roll head tilts while seated upright and spun about an Earth-vertical axis. The spin rate was incremented when head tilts did not subjectively elicit the illusion. Subjects completed one 25-minute session on each of 10 days.RESULTSThe spin rate at which subjects felt no cross-coupled illusion increased in all subjects from an average of 1.8 rotations per minute (RPM) (SD: ±0.9) at the beginning of the protocol to 17.7 RPM (SD: ±9.1) at the end. For off-axis centrifugation producing 1G at the rider's feet, this corresponds to a reduction in the required centrifuge diameter from 552.2 to 5.7 meters. Subjects reported no more than slight motion sickness.CONCLUSIONSAcclimation to the cross-coupled illusion, such as that accomplished here, is critical for feasibility of short-radius centrifugation for AG implementation.

Heavy Fraction Separation From Used Lube Oil Using Thin Film Evaporator

Used lube oil is a dangerous waste that must be treated before disposed on the environment. Used lube oil treatment process consists of several stages, one of them is the separation of heavy fraction. Some equipment system can be used to complete this process, and thin film evaporator (TFE) is chosen for this research. The goal of this research is to understand the effect of temperature and rotor rotation on the heat transfer that happens in the distillation process using thin film evaporator. Simulation using Aspen Plus is used and is validated by manual calculation using Matlab. Temperature is varied between 250 – 330 °C and rotor rotation are varied between 0 – 60 rotations per minute (RPM) in a vacuum pressure of 2.53 kPa. From this research, the relation between operating temperature and rotor rotation in thin film evaporator to the vapor fraction produced is directly proportional. The optimum operating condition in this research was found at a temperature of 310 °C with the agitator rotational speed of 30 RPM.

Noise characterization of a subsea tidal kite.

This paper presents the first noise measurements of a quarter-scale subsea tidal kite (anchored to the sea floor by a tether and flying in a figure-eight configuration in the water column) operating in field conditions. Challenges in the measurement and post-processing of the data are detailed. Results are presented for three operating conditions of the kite: (1) varying turbine rotations per minute (RPM), (2) varying kite speed, and (3) a twisted tether. Turbine RPM was identified as the main parameter influencing noise emissions.

Extreme shear processing for exfoliating organoclay in nanocomposites with incompatible polymers

Twin screw extrusion at speeds exceeding several thousand rotations per minute (RPM) has the potential to provide extreme shear typically required to break up aggregates and provide good dispersion in polymer nanocomposites. In this work, a novel twin screw extruder with ultra-high screw speed capability has been used to compound the polystyrene (PS) with organically modified nanoclay without using any compatibilizer. The rheological properties and the morphology of the nanocomposites were investigated and compared with simulation after compounding. Screw profiles imparting more and less aggressive mixing were compared over a range of screw speeds from 400 to 4000 RPM. Morphological characterization revealed the necessity of intense shear stress for achieving intercalation and exfoliation when chemical interactions between filler and matrix are unfavorable. The nanocomposites exhibited greater elasticity indicating reinforcement up to a critical screw speed for each screw profile, but further increasing the screw speed resulted in significant polymer degradation, and thus lower viscosity and storage modulus. Moreover, based on calculations of the theoretical adhesion force between the organoclay layers and the shear stress imparted through mixing, the optimized screw speed for a specific screw profile was determined that would overcome lamellar adhesion to form exfoliated nanocomposites, while minimizing the effect of degradation. The resulting model could be extended to any well-defined extruder system as well as other agglomerated nanofillers.

The effects of static, oscillating, and oscillating with dwell time retort motions on the rate of heat penetration of a food simulant processed in a pouch

The objective of this work was to study the effect of three different retort motions on the rate of heat penetration in pouches. Pouches were processed in a water spray batch retort system using static, oscillating continuously at a speed of 10.5 rotations per minute (RPM) with an angle of 15 degrees, and oscillating at 10.5 rpm at a 15 degree angle with a 15-s hold. There was no difference in the rate of between static and oscillating processes (p > .05). There was a difference in the between static and oscillating with a hold processes (p < .05). At a 90% confidence interval, there was also a difference between the rate of heat penetration between the oscillating and oscillating with a hold processes (p > .05, p = .056). The location of the pouches on the retort rack did not influence the rate of heat penetration within the three methods or between the three methods (p > .05). Practical applications Despite novel technological developments for creating sterile shelf stable products, thermal processing is still the most reliable method. Creating innovation within thermal processing by using different methods of motion to create faster heating profiles can improve the quality of products. This research can be used for optimizing retort processes for food products in pouches. Processing with motion has been seen to reduce the processing time which can increase nutrient retention, reduce thermal abuse, and ultimately save money and increase production. Retort food manufacturers can use oscillating and hold motion to make higher quality products in less time than static motion.