Spin Speed Research Articles

Free vibration analysis of a spinning functionally graded spherical–cylindrical–conical shell with general boundary conditions in a thermal environment

Based on the first-order shear deformation theory (FSDT) for shells, the free vibration of a spinning functionally graded (FG) spherical–cylindrical–conical (SCC) shell with arbitrary boundary conditions subjected to a thermal environment is investigated. The centrifugal forces, the Coriolis forces, and the initial hoop tension caused by spin are all considered in the theoretical modeling. The model is analyzed using the domain decomposition method. The penalty method is used to model the continuity and arbitrary boundary conditions. Validity study is performed by comparing with the results from finite element analyses for special cases. Finally, the effects of the power-law index, the temperature loads, the spinning speed, and the geometrical parameters on the free vibration characteristics, as well as the influences of structural configuration on the critical spinning speed, are investigated. It is found that the configuration of a spinning SCC shell has significant effect on its natural frequency and critical speed under a fixed shell weight. The natural frequencies approximately converge into three values with increases in the circumferential wave number. The FG–SCC shell’s cone angles at which the minimum and maximum natural frequencies occur are not affected by the spinning speed and the power-law index.

Speed-Dependent Bearing Models for Dynamic Simulations of Vertical Rotors

Many dynamic simulations of a rotor with a journal bearing employ non-linear fluid-film lubrication models and calculate the bearing coefficients at each time step. However, calculating such a simulation is tedious and computationally expensive. This paper presents a simplified dynamic simulation model of a vertical rotor with tilting pad journal bearings under constant and variable (transient) rotor spin speed. The dynamics of a four-shoes tilting pad journal bearing are predefined using polynomial equations prior to the unbalance response simulations of the rotor-bearing system. The Navier–Stokes lubrication model is solved numerically, with the bearing coefficients calculated for six different rotor speeds and nine different eccentricity amplitudes. Using a MATLAB inbuilt function (poly53), the stiffness and damping coefficients are fitted by a two-dimensional polynomial regression and the model is qualitatively evaluated for goodness-of-fit. The percentage relative error (RMSE%) is less than 10%, and the adjusted R-square (Radj2) is greater than 0.99. Prior to the unbalance response simulations, the bearing parameters are defined as a function of rotor speed and journal location. The simulation models are validated with an experiment based on the displacements of the rotor and the forces acting on the bearings. Similar patterns have been observed for both simulated and measured orbits and forces. The resultant response amplitudes increase with the rotor speed and unbalanced magnitude. Both simulation and experimental results follow a similar trend, and the amplitudes agree with slight deviations. The frequency content of the responses from the simulations is similar to those from the experiments. Amplitude peaks, which are associated with the unbalance force (1 × Ω) and the number of pads (3 × Ω and 5 × Ω), appeared in the responses from both simulations and experiments. Furthermore, the suggested simulation model is found to be at least three times faster than a classical simulation procedure that used FEM to solve the Reynolds equation at each time step.

Free Vibration Analysis of a Spinning Composite Laminated Truncated Conical Shell under Hygrothermal Environment

This paper is concerned with free vibration characteristics of a spinning composite laminated truncated conical shell subjected to hygrothermal environment. Hygrothermal strains are introduced into the constitutive law of single-layer material, and fiber orientation lies symmetrically with respect to the midplane of the composite shell. Considering the spin-induced Coriolis and centrifugal forces, as well as initial hoop tension, the governing equations of free vibration of the composite conical shell with hygrothermal effects are derived on the basis of Love’s thin-shell theory and Hamilton’s principle. The solution of the equations is derived using the Galerkin approach. Then, a detailed parametric study on natural frequencies and critical spinning speeds is numerically performed. Results indicate that the Coriolis force induces an asymmetric influence on natural frequencies of forward and backward traveling waves, while the centrifugal force enhances the frequencies of both traveling waves symmetrically. Initial hoop tension plays a major role in the increase of critical spinning angular speed. Temperature, moisture concentration, and design parameters show the significant influence on the free vibration characteristics of the conical shell, and thermal expansion deformation is nonnegligible in the free vibration analysis.

Uji kinerja mesin pengupas buah pinang kering menggunakan mekanisme pengupas tipe impact rotary poros horizontal

Indonesia was one of the exporting countries of betel nut, lately the selling price of betel nut has increased. Betel nut that has a high selling price, was an old betel nut that has been dried. Various forms of betel nut that were sold in the market include whole betel nut, split betel nut and sliced betel nut. The purpose of this study was to find out the effect of the spin speed of the peeling mechanism on the timing and peeling result, and to find out the best interaction between the spin speed and the number of peeling rods that able to producing the best peeling efficiency. The method used in the study was a randomized design experiment consisting of two factors: spin speed (1000 rpm, 1200 rpm, 1400 rpm, 1600 rpm) and the number of peeling rods (12, 18 and 24) with 12 testing interactions. The main parameter observed was the percentage of peeled fruit with whole condition. The performance test result proved that the increase of the spin speed peeling mechanism has an effect on the efficiency of time, when the speed spin of the peeling mechanism increases, the time it takes to peel the dried betel nut was decreases. But this condition was not directly proportional to the increasing percentage of dried betel nut that was whole peeled. The best peeling interaction was at a speed of 1400 rpm, with 18 peeling rods. This interaction produced peeling efficiency, 88% of whole peeled fruit, 12% of split peeled fruit and 0% of the unpeeled fruit.

Critical speed and frequency behavior of rotating joined FG-CNTRC conical-conical shells

This paper provides information on critical speed and frequency behavior of rotating joined functionally graded carbon nanotube reinforced (FG-CNTRC) conical-conical shells. Furthermore, frequency bifurcation as a consequence of rotational effects is investigated. The shell is assumed to be composed of an isotropic polymer matrix that is reinforced by uniformly or functionally distributions of carbon nanotubes (CNTs). The structure’s kinematics originates from the first order shear deformation theory (FSDT). To derive spin-based motion equations, Coriolis and centrifugal forces together with initial hoop tensions are propounded through the Hamilton’s principle. Moreover, matching and boundary conditions are ascertained to supplement the governing equations. To discretize the governing equations meridionally, the generalized differential quadrature (GDQ) technique is employed. After validity checking, some significant parameters like cones’ angles, rotation speed, edge supports, CNT volume fractions and dispersion patterns that play effective roles on the critical speed and vibration characteristics are examined. It is revealed that by enhancing spinning speed, frequencies of different FG patterns converge. In addition, difference between backward and forward frequencies decreases as the circumferential mode number increases.

AFM/XPS Analysis of the Growth and Architecture of Oriented Molecular Monolayer by Spin Cast Process and Its Cross-Linking Induced by Hyperthermal Hydrogen

We used atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to comprehensively study the growth and the cross-linking of dotriacontane (C32H66) nanofilms that were deposited on a silicon wafer by the spin-coating process. It was found that the molecular structure of the nanofilms changed with C32H66 concentration at the given spin speed, of which a monolayer of oriented C32H66 molecules, formed at lower deposition concentrations, was composed of a perpendicular orientation state with the molecular long-chain axis perpendicular to the substrate surface and a parallel orientation state, while the perpendicular state was essentially dominant when the nanofilm was formed at higher deposition concentrations. The shortening of the first perpendicular layer in AFM topography could be attributed to the mixing of both parallel and perpendicular lamellas in the first layer. XPS analysis indicated that the average thickness of the layer almost linearly increased with the C32H66 concentration. The monolayer of C32H66 film could be cross-linked by a hyperthermal hydrogen-induced cross-linking (HHIC) at a few eV via kinetic collision to cleave C-H bonds. The water contact angle measurement of extensive HHIC on C32H66 nanofilms disclosed that the static contact angle decreased with the treatment time (or fluence) and saturated after full cross-linking of the film.

Optimization of formation of phase pure hydroxyapatite and fabrication of electrochemically stable HAP coatings on 316L SS for orthopedic applications

AbstractImpact of sintering temperature and aging time was investigated on purity and phase of hydroxyapatite powders synthesized through sol–gel process. Phase, composition, and morphology of the prepared hydroxyapatite powders were characterized using X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR), and scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS). Plausible mechanism respective to the formation of HAP from the precursors Ca(NO3)2·4H2O and triethyl phosphite (TEP) by sol–gel process was determined from 31P NMR analysis. Further, the development of hydroxyapatite coatings on 316L SS metallic surfaces was done by varying the spin coating parameters such as spin speed, spin time, and sintering atmosphere, and their corrosion resistance behavior in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and TAFEL polarization analysis. From the results, we inferred that the HAP coatings deposited on 316L SS surfaces at 3000 rpm/min under nitrogen atmosphere sintering have shown improved corrosion resistivity. The effect of aging time, sintering atmosphere, and spin speed was evaluated in terms of corrosion resistance behavior.

Optimization of Process Parameter on AA8052 Friction Stir Welding Using Taguchi’s Method

The Taguchi method of experimental design was employed in this study to scrutinize the impact of welding processing factors, including rotating speed, travelling speed, and pin profile on ultimate tensile strength, microhardness, and impact strength of the Friction Stir Welded AA 8052 joint. The S/N values for each process specification were calculated using an orthogonal array of L9 design. The 1150 rpm and 28.5 mm/min were the greatest tensile strength, microhardness, S/N evaluation parameters, respectively, and a used cylinder pin. A combination of 1150 rpm and 32.5 mm/s and a conical cylindrical pin provided the best impact toughness results. According to the analysis of variance, the spinning speed, travel feed, and pin shape had a 37.34% impact on ultimate strength and a further 34.33% impact on microhardness. A second set of tests verified the findings, with tensile strength of 349.96 MPa, hardness of 115.31 H, and impact strength of 7.95 kJ.

Melt Spinning of Elastic and Electrically Conductive Filament Yarns and their Usage as Strain Sensors

Electrically conductive fibers are required for numerous fields of application in modern textile technology. They are of particular importance in the manufacturing of smart textiles and fiber composite systems with textile-based sensor and actuator systems. Elastic and electrically conductive filaments can be used as strain sensors for monitoring the mechanical loading of critical components. In order to produce such sensorial filaments, thermoplastic polyurethane (TPU) is compounded with carbon nanotubes (CNT) and melt spun. The mechanical performances of filaments produced at different spinning speeds and containing different amounts of CNT were tested. Furthermore, the correlation between the specific electrical resistance of the filaments and the mechanical strain were analyzed depending on the CNT-content and the spinning speed.

Exploring the Applications of Carbon-Detected NMR in Living and Dead Organisms Using a 13C-Optimized Comprehensive Multiphase NMR Probe.

Comprehensive multiphase-nuclear magnetic resonance (CMP-NMR) is a non-invasive approach designed to observe all phases (solutions, gels, and solids) in intact samples using a single NMR probe. Studies of dead and living organisms are important to understand processes ranging from biological growth to environmental stress. Historically, such studies have utilized 1H-based phase editing for the detection of soluble/swollen components and 1H-detected 2D NMR for metabolite assignments/screening. However, living organisms require slow spinning rates (∼500 Hz) to increase survivability, but at such low speeds, complications from water sidebands and spectral overlap from the modest chemical shift window (∼0-10 ppm) make 1H NMR challenging. Here, a novel 13C-optimized E-Free magic angle spinning CMP probe is applied to study all phases in ex vivo and in vivo samples. This probe consists of a two-coil design, with an inner single-tuned 13C coil providing a 113% increase in 13C sensitivity relative to a traditional multichannel single-CMP coil design. For organisms with a large biomass (∼0.1 g) like the Ganges River sprat (ex vivo), 13C-detected full spectral editing and 13C-detected heteronuclear correlation (HETCOR) can be performed at natural abundance. Unfortunately, for a single living shrimp (∼2 mg), 13C enrichment was still required, but 13C-detected HETCOR shows superior data relative to heteronuclear single-quantum coherence at low spinning speeds (due to complications from water sidebands in the latter). The probe is equipped with automatic-tuning-matching and is compatible with automated gradient shimming─a key step toward conducting multiphase screening of dead and living organisms under automation in the near future.

Whirl dynamics of an axially functionally graded liquid-filled rotor considering shear deformation and rotary inertia

In this study, whirl characteristics and stability of an axially functionally graded (AFG) liquid-filled rotor are investigated. The rotor is modeled based on the spinning Timoshenko beam theory. The governing equations for flexural vibration are derived via Hamilton’s principle. For pinned–pinned AFG liquid-filled rotor, the analytical solutions are derived for both the exact whirl frequency equation and the stability model. To validate the present formulations, comparative studies by numerical solutions available in the literature are conducted. Some numerical examples are performed to investigate the effects of gradient parameter, mass ratio, cavity ratio, rotary inertia, and shear deformation on the whirl speed, the critical spinning speed, and the stability of the AFG liquid-filled rotor system. The results show that these parameters have noticeable influences on dynamic behavior and stability of the rotor system. In particular, the rotary inertia and shear deformation play an important role in the stability analysis for different length rotors.

Behavioral analysis of habit formation in modern slot machine gambling

ABSTRACT Habit formation is a key process in contemporary models of addictive behaviors but has received limited attention in the context of gambling and problem gambling. Methods for examining habit formation and expression in relation to gambling are also lacking. In this study, 60 participants with no prior slot machine experience attended three sessions spaced 6–8 days apart, during which they played a short 200-spin session on a realistic simulation of a modern multi-line slot machine. Behavioral data were analyzed to characterize habit formation within and between sessions. Fixed-effects regressions, integrating trial- and session-level effects, assessed predictors of gambling speed (spin initiation latencies) and betting rigidity (the likelihood of switching the bet amount), as two putative markers of habit formation. Participants gambled faster and showed less variability in betting strategy as they accumulated experience in the number of trials and sessions gambled. Simultaneously, as the number of sessions gambled increased, participants showed a more pronounced tendency to slow their betting after larger wins (i.e. the post-reinforcement pause increased from session 1 to session 3). Our methods provide a basis for future research to examine habits in the context of slot machine gambling.

Application of active magnetic bearings in control and estimation of geared-rotor faults in high speed offset spur gear transmission system

This study is focused on the mathematical modelling, analysis, active transverse vibration control and fault analysis of a single-stage spur geared-rotor system. It uses Active Magnetic Bearings (AMBs) as an auxiliary bearing in addition to the conventional mechanical bearing in rotor fault detection considering the dynamic model with gyroscopic effects. The change in dynamic forces primarily due to the mesh deformation, gear runout, and variable transmission error are considered, which causes unwanted vibration and noise. To prevent the damage of gears and other supporting structures, these forced vibrations and control currents are meticulously investigated. From the dynamic responses of geared-rotor, the AMB control the stiffness and damping to minimize the transmission of forced vibrations to the mountings by closed-loop feedback control system. For an accurate modelling the dynamic transmission error is taken in two orthogonal transverse directions, which has asymmetric transmission error characteristics. Full spectrum is used for frequency domain analysis with tilting phenomena of the gears at high spin speed. An identification algorithm is developed for fault detection and estimation of system parameters from vibration and current of the proposed geared-rotor-AMB system. The robustness of the proposed algorithm is verified with different added percentage of noise and modeling errors.

Realization of magneto-optical near-zero-index metamaterial by using an array of spinning cylinders

Magneto-optical materials have found wide applications in optical-functional devices and topological photonics due to their magneto-optical activity and time-reversal symmetry breaking. However, there are rare kinds of magneto-optical materials in nature and their working frequencies are mostly limited to the microwave regime which largely limits the applications. In this work, we propose a scheme to realize an effective magneto-optical near-zero-index metamaterial, that is, using an array of spinning cylinders. The material of the cylinder can be arbitrary and the strength of the magneto-optical effect parameter can be tuned according to the spinning speed. Therefore, the operating frequency can go beyond the microwave regime and in principle cover much higher frequencies, which largely expands the range of operating frequency of magneto-optical materials. The results are verified by numerical full-wave simulations.

The Characteristic Behaviour of the Stretch-Orientation Zone during High-Speed PET Spinning**

Abstract A theory is proposed to separate the on-line stress in the stretch-orientation zone during high speed PET spinning into two parts: the thermodynamically equilibrium or quasi-equilibrium stress associated with rubber elasticity and the non-equilibrium driving stress, which leads to coordinated orientation of the macromolecular chains. Precise and simultaneous measurements of the online spinning parameters at five spinning speeds, ranging from 2200 to 4200 m/min, were conducted. A physical model consisting of a dashpot placed in parallel with a Gaussian network was found to describe well the behaviour of the stretch-orientation zone of high speed PET spinning.

The Effects of Spin-Coating Rate on Surface Roughness, Thickness, and Electrochemical Properties of a Pt Polymer Counter Electrode

In a dye-sensitized solar cell (DSSC) the CE is responsible for the collection of electrons from the external circuit and the electrocatalysis reaction of the electrolyte. This paper reports the effect of spin-coating rate on the surface roughness, film thickness, and electrochemical properties of a Pt polymer counter electrode (CE). In this work, the spin-coating rate has been investigated in the range 1000-6000 rpm and the results indicate that low spin-coating speeds produce the thickest films with the smoothest surfaces, while high spin speeds produce thinner films with higher surface roughness. The thickness of the film decreased from 7.03 μm at 1000 rpm to 1.30 μm at 6000 rpm. Results also indicate a decrease in electrocatalysis properties and conductivity with the increase in film spin-coat rate. The resistance at the CE/electrolyte interface decreased from 9.3 Ω at 1000 rpm to 14.8 Ω at 6000 rpm. The spin-coating rate also affects the light transmittance of the CE and photovoltaic characteristics of the DSSC, such as current density and overall cell conversion efficiency. This study demonstrates a method to develop cost-effective counter electrodes for application in bifacial solar cells.

Fabrication of ultra-thin laser induced graphene electrodes over negative photoresist on glass for various electronic applications

Photoresists play a pivotal role in pattern transfer applications to achieve microstructures with high aspect ratios and vertical sidewalls for MEMS and semiconductor industries. Negative photoresists (NPR) have been leading the photoresist industry ever since their inception with excellent chemical resistance and high thermal and mechanical stability. However, owing to its low conductivity, NPR is restricted only to structural and sacrificial applications. For this first time, this work showcases the utilization of NPR to obtain ultra-thin and highly conductive laser Induced graphene (LIG) over glass substrates through laser ablation. Different combinations of NPR samples were considered at different spin speeds (2000 rpm to 4000 rpm) to obtain various thickness values to comprehend the effect of parameters, such as UV exposure, baking conditions, and photoresist thickness over obtained conductivity of the LIG. It was observed that samples which were coated with NPR at 4000 rpm followed by hard baking without UV exposure exhibited a conductivity of 529.7 S/m upon repeated ablation of laser. The functionality of the fabricated thin film electrodes was tested for biofuel cell and electrochemical applications. The novel method to create conductive patterns over glass substrates not only pave a possible way for realizing glass-based electronic devices but also open up new avenues for microelectronic industry.

Liquid-Infused Porous Film Self-Assembly for Superior Light-Transmitting and Anti-Adhesion.

Liquid-Infused Surfaces (LISs), particularly known for their liquid-repelling feature, have demonstrated plenty of applications in the medical, marine, and energy fields. To improve the durability and transparency highly demanded on glass-based vision devices such as an endoscope, this study proposed a novel self-assembly method to fabricate well-ordered porous Poly-Styrene (PS)/Styrene–Butadiene–Styrene (SBS) films by simply dripping the PS/SBS dichloromethane solutions onto the glass before spinning. The effects of the solutions’ concentrations and spin speeds on the porous structure were experimentally investigated. The results showed that a certain mass ratio of PS/SBS can make the structure of the ordered porous film more regular and denser under the optimal solution concentration and spin-coating speed. Superior transparency and durability were also realized by dripping silicone oil on the porous film to build a liquid-infused surface. Applications of the as-prepared surface on devices like endoscopes, viewfinders, and goggles have been explored respectively.

Size-dependent dynamical analysis of spinning nanotubes conveying magnetic nanoflow considering surface and environmental effects

In this article, a nonlocal strain gradient theory (NSGT) incorporating the thickness effect is developed for dynamics and stability analysis of Y-shaped nanoscale tubes containing magnetic flow with spin motion in magneto-hygro-thermal environments. A detailed study is also conducted to elucidate the impacts of various parameters, such as magnetic flow, scale parameters, fluid velocity, spin speed, downstream elbow angle, localized masses, attached springs, surface effects, and complex environments on the system vibration. The scale-dependent dynamical equations are obtained using Hamilton's principle. The Galerkin scheme is applied to solve the eigenvalue problem of the system. Stability diagrams and vibrational frequencies are obtained. Furthermore, the divergence threshold of the structure is acquired analytically. The outcomes showed that the destructive effects of moisture and nonlocality on the system stability could be alleviated by the stabilizing effects of the magnetic field, strain gradient parameter, and surface effect. Furthermore, it is found that in low- and high-temperature conditions, the temperature variation has an opposite impact on the system stability. The results can be served as a comprehensive benchmark for optimum design of advanced doubly gyroscopic nanoscale systems transporting nanoflow.

Pulse induced resonance with angular dependent total enhancement of multi-dimensional solid-state NMR correlation spectra

We demonstrate a new resonance condition that obeys the relation Δδ=nνR/2, where Δδ is the chemical shift difference between two homonuclear-coupled spins, νR is the magic-angle spinning speed and n is an integer. This modulation on the rotational resonance recoupling condition is obtained by the application of rotor-synchronous 1H pulses when at least one proton is dipolar-coupled to one of the homonuclear spins. We suggest a new experimental scheme entitled ‘pulse induced resonance with angular dependent total enhancement’ (PIRATE) that can enhance proton-driven spin diffusion by the application of a single 1H pulse every rotor period. Experimental evidence is demonstrated on the two carbon spins of glycine and on the Y21M mutant of fd bacteriophage virus. Numerical simulations reveal the existence of the resonances and report on the important interactions governing these phenomena.