Cylindrical Device Research Articles

Possibilities of Controlling the Dynamic Properties of a Cylindrical Piezoceramic Acousto-electronic Device with Two-frequency Resonance Excitation

Possibilities of Controlling the Dynamic Properties of a Cylindrical Piezoceramic Acousto-electronic Device with Two-frequency Resonance Excitation

Physical Insights Into Cylindrical Illusion Device With Isotropic and Homogeneous Materials

The cylindrical illusion device with isotropic and homogeneous materials is studied deeply based on the Mie scattering theory. The formula for illusion of core-shell structure is derived in the quasistatic approximation. Whether the inner core is a dielectric or PEC material, it can be equivalent to a certain target cylinder after wrapping a properly designed shell. We investigate what range of permittivity of the shell may be possible to achieve a target, which can provide convenient and intuitive design charts for an approximate design a core-shell illusion device. It is found that the number for the thickness of the shell is zero, one or two when the permittivities of the target and the shell take a variety of parameters. Moreover, the physical insights into the parameters' distribution are explained by analyzing the electric dipole moments in each part of the core-shell structure. It is interesting to see that a double negative material can be equivalently achieved by a PEC core coated with a positive magnetic material, which may offer a new design approach for the realization of double negative materials. The scattering widths and full-wave simulations are given to verify correctness of the proposed method.

Experimental investigations and optimization of process parameters of meshed-wick heat pipe

Heat pipes are used to transfer heat, which are hollow cylindrical shape device filled with small amount of working fluid, which can change its phase. The rate of heat transfer in heat pipes compared to normal heat exchanging devices is more. Depending on the applications of heat transfer various heat pipes are being designed. Methanol fluid is used with 50% fill ratio. It is made of copper with outer diameter of 15.88mm and inner diameter of 14.88mm. It consists of a screen mesh made of copper powder inside it with thickness of 0.5mm. Due to heat input methanol changes its phase from liquid to vapor. The vapor loses its heat and changes its phase back to liquid in the condenser. At the condenser section the vapour gives up it heat and changes its phase from vapour to liquid. The screen mesh assists the flow of condensed working fluid through capillary action. Optimized the results by “Taguchi method” using “Minitab software”. The Thermal analysis was done with the optimum conditions, which were obtained as a result from the optimization method by Ansys Fluent software. Then finally compared the thermal parameters obtained from experiments with the Thermal analysis result. It is found the maximum heat transfer rate is optimized using meshed wick heat pipe conditions.

Determination of the efficacy of monensin capsule (continuous release capsule) on metabolic parameters in transition dairy cows

Monensin is an ionophore antibiotic that changes the population of rumen bacteria. The aim of this study was to determine the effects of monensin controlled capsule administered 3 wk before calving on blood metabolites (serum beta-hydroxybutiric acid (BHBA), cholesterol (CHOL), urea, creatinine (CREA), gamma glutamyl transferase (GGT), aspartate aminotransferase (AST), total protein (TP), phosphorus (P), magnesium (Mg+), calcium (Ca++), glucose (GLU) and plasma non-esterified fatty acids (NEFA) concentration) and milk yield in the pre and post-calving term. 50 Holstein-Friesian cows were selected from the same flock. Blood samples were taken 3 weeks before the expected calving date and during weeks 1, 2, 4, 6 and 8 post calving. Cows were divided into two group: a study group (Group M, n:40) and a control group (Group C, n: 10). The group M orally received a cylindrical device (Kexxtone, ELANCO Animal Health, Guelph, ON, Canada) and the group C received no treatment. BHBA and NEFA was lower (P˂0,.05) in group M compared with group C in the 6 and 8 week post-calving. GLU was higher (P˂0.05) in group M compared with group C in the 4 week post-calving. Urea was higher (P˂0.05) in group M compared with group C in the 1 week post-calving. There was no statistically difference between two groups (P˂0.05) in milk yields. Although milk yield was similar in both groups, the change in concentration of BHBA, NEFA, GLU and urea showed that monensin CRC could be as a glycogenic precursor.

Illusion Properties in Perfect Cylindrical Devices

In this paper, illusion properties in a class of perfect cylindrical devices that contain a singular radial mapping have been reported. In these media, illusion can be implemented using alternating structure of only two kinds of metamaterial: zero index metamaterials and perfect electric conductors. Full-wave simulations in two dimensions have been performed to verify its functionality and its illusionary effects for TM polarization incident wave. The duality principle can be applied for TE polarization.

Research Inside a Gas Heating Device with Different Heat Transfer Medium

Natural gas heating device occupies an important position in natural gas industry, and the most widely used one is the cylindrical heating device with heat transfer medium. The key factors affecting the thermal efficiency of the cylinder gas heating device with heat transfer medium are the type of heat transfer medium and the flow field organization. In order to study the influencing factors of thermal efficiency of the heating device, a visualized practical gas heating device experiment system was established, and a two-dimensional heat transfer model fitting the real object was established, too. The unstructured fitting mesh was used to divide the physical model, and the finite volume method was used for discrete solution, while discrete coordinate (DO) radiation model is used to solve radiation equation. In this paper, water and ethylene glycol are used as heat transfer media to simulate and measure the heat flow field in the cylinder. The results show that ethylene glycol can broaden the application range of gas heating device. Under the same experimental conditions, the heat efficiency of the heating device with ethylene glycol as heat transfer medium is at least 3.8% higher than that of the heating device with water as heat heat transfer medium. The thermal efficiency of gas heating devices is generally less than 87%.

Cylindrical ultrasound transducers for intravascular and endolumenal imaging applications

Conventional ultrasound imaging transducers are fabricated using planar geometries—of materials and in most subsequent processing (bonding, dicing, etc.); this can lead to complications in assembling catheter- or endoscope-based devices, and/or significant inherent limitations in their design and application. Miniature cylindrical transducer devices offer the potential for more straightforward design for 360-deg imaging applications, albeit with unique fabrication challenges. We have developed a novel technique for processing cylindrical ultrasound transducer geometries, and used it to fabricate prototype devices designed for intravascular and endolumenal applications. We created a custom dicing setup allowing a tube of radially poled piezoceramic (PZT-4) as small as 4.6 Fr (1.53 mm diameter) to be cut circumferentially, to a specified depth or completely through the wall of the tube, at precise axial locations. The resulting cylindrical transducer was connected to a function generator and power amplifier, and driven at 7.5 MHz to generate axisymmetric, radially directed acoustic radiation force impulse (ARFI) displacements up to 19 μm in a tissue-mimicking elasticity phantom. This demonstrates that miniature cylindrical transducers can be made to enable 360-deg elasticity imaging of the mechanical properties and structure of tissues, to identify vulnerable atherosclerotic plaques or quantify softening of the cervix prior to labor onset.Conventional ultrasound imaging transducers are fabricated using planar geometries—of materials and in most subsequent processing (bonding, dicing, etc.); this can lead to complications in assembling catheter- or endoscope-based devices, and/or significant inherent limitations in their design and application. Miniature cylindrical transducer devices offer the potential for more straightforward design for 360-deg imaging applications, albeit with unique fabrication challenges. We have developed a novel technique for processing cylindrical ultrasound transducer geometries, and used it to fabricate prototype devices designed for intravascular and endolumenal applications. We created a custom dicing setup allowing a tube of radially poled piezoceramic (PZT-4) as small as 4.6 Fr (1.53 mm diameter) to be cut circumferentially, to a specified depth or completely through the wall of the tube, at precise axial locations. The resulting cylindrical transducer was connected to a function generator and power amplifier...

Multichannel processing of vibrational measurements: A constrained subspace application.

Monitoring mechanical systems operating in uncertain environments contaminated with both environmental disturbances and noise lead directly to low signal-to-noise-ratios, creating an extremely challenging processing problem, especially in real-time. In order to estimate the performance of a particular system from uncertain vibrational data, it is necessary to identify its unique resonant (modal) frequency signature. The monitoring of structural modes to determine the condition of a device under investigation is essential, especially if it is a critical entity of an operational system. The development of a model-based scheme capable of the on-line tracking of the inherent structural modal frequencies by applying both constrained subspace identification techniques to extract the modal frequencies and state estimation methods to track the evolution is discussed. An application of this approach to a cylindrical structural device (pipe-in-air) is analyzed based on theoretical simulations along with controlled validation experiments, including injected anomalies illustrate the approach and performance. Statistics are gathered to bound potential processors for real-time performance employing these constrained techniques.

Avalanches triggered by Kelvin-Helmholtz instability in a cylindrical plasma device.

A profile-evolving simulation of the Controlled Shear Decorrelation Experiment (CSDX) linear device is performed with our newly developed code. The simulation result shows an excellent agreement with the experimental observations of profiles and fluctuations of plasma density and electric potential in the B=1000 G standard discharges, suggesting the mechanism of their evolutions. According to our simulation, an avalanche of plasma density, featuring a rapid destruction of particle profile, is triggered every time the dominant instability transits from near adiabatic collisional drift wave to non-adiabatic Kelvin-Helmholtz instability. The avalanches always start at the point where the local vorticity is the maximum among the whole device. A critical vorticity is found for any avalanche to happen. The avalanches always lead to intermittent particle and heat convective structures outside the main plasma column, and these structures are ejected out as avaloids when zonal flow intensity at birth time is weak.

Performance evaluation of a cylindrical air-lift mixer-settler device and optimization of process parameters for the extraction of uranium (VI) from nitric acid medium

A customized single-stage cylindrical combined air lift mixer-settler (C-CALMIX) device has been developed and its performance was evaluated by studying the extraction behavior of U(VI) in a solution of 1.1 M tri-n-butyl phosphate (TBP) in n–dodecane (n-DD) from 4 M nitric acid medium, at 298 K. The extraction of U(VI) was studied as a function of process parameters of the C-CALMIX such as flow-rate of organic and aqueous phases, ratio of organic to aqueous flow-rates, air flow-rate etc., that are amenable for variation. The distribution ratio of U(VI) obtained under dynamic conditions in a C-CALMIX was compared with those obtained in a batch equilibrium mode. The process parameters were optimized to obtain high distribution ratio of U(VI) in C-CALMIX, comparable to that obtained at batch equilibrium mode without compromising the throughput of C-CALMIX. The stripping behavior of U(VI) from the loaded organic phase was studied using 0.01 M nitric acid. The results are reported in this paper.

Experimental study of porosity and effective thermal conductivity in packed bed of nano-structured FeTi for usage in hydrogen storage tanks

The porosity and effective thermal conductivity, which were measured simultaneously, changed owing to expansion during hydrogen absorption and contraction during hydrogen desorption. The metal hydride used in the experiment was a newly developed nano-structured FeTi (n-FeTi) by mechanical alloying. The porosity was measured by directly observing the changes in the volume of a metal hydride packed bed under free expansion. In the authors' previous study of LaNi5, the volume of the packed bed gradually increased, whereas the total volume of the n-FeTi packed bed decreased with increase in the cycles of expansion and contraction. The effective thermal conductivity measurements of the metal hydride packed bed were carried out using a cylindrical device with heating from a central heater. The results showed that the effective thermal conductivity of n-FeTi changes from 0.4 to 1.1 W/mK with rise in reacted fraction and decrease in porosity.

Studies on virtual electrode and ion sheath characteristics in a cylindrical inertial electrostatic confinement fusion device

An experiment on the formation of virtual electrode and ion sheath characteristics has been carried out in a hot cathode discharge plasma produced inside a cylindrical inertial electrostatic confinement fusion device. The plasma parameters such as electron temperature and plasma density are evaluated by using a Langmuir probe. Transition from a single potential well to multiple potential wells, i.e., virtual electrodes inside the cathode grid, is observed when the bias voltage applied to the cathode is increased from –1000 to –5000 V. An emissive probe has been used for the measurement of plasma potential due to its greater accuracy than the conventional Langmuir probe. Ion sheath potential structures and presheath characteristics for different cathode potentials have been investigated using the emissive probe and are found to be consistent with the Debye sheath model. A detailed discussion on the obtained results has been presented in this paper.

Effect of permanent magnets on plasma confinement and ion beam properties in a double layer helicon plasma source

The work described in this article was carried out to investigate how permanent magnets (PM) affect the plasma confinement and ion beam properties in an inductively coupled plasma which expands from a helicon source. The cylindrical plasma device Njord has a 13 cm long and 20 cm wide stainless steel port connecting the source chamber and the diffusion chamber. The source chamber has an axial magnetic field produced by two coils, with magnetic field lines expanding into the diffusion chamber. Simulations have shown that the field lines leaving the edge of the source hit the port wall, causing a loss of electrons in this section. In the experiments performed in this work, PMs were added around the port walls near the exit of a plasma source and the effect was investigated experimentally by means of a retarding field energy analyser probe. The plasma potential, ion density and ion beam parameters were estimated, and the results with and without the PMs were compared. The results showed that the plasma density in the centre can in some cases be doubled, and the density at the edges of the plasma increased significantly with PMs in place. Although the plasma potential was slightly affected, and the beam velocity dropped by ${\sim}$ 10 %, the ion beam flux increased by a factor of 1.5.

1D photonic crystal filled with low-temperature plasma for controlling broadband microwave transmission

A 1D plasma photonic crystal (PPC) is filled with plasmas and slab dielectrics in a large volume cylindrical glow discharge device. The parameters of the PPC are designed to meet the transmission condition of broadband microwave (1.5GHz-12GHz) according to the photonic crystal theory in which the thickness of the plasma is comparable to the wavelength. The transmission characteristics of broadband microwave in this plasma photonic crystal are demonstrated experimentally. The experiments show some unique characteristics of microwave in the PPCs, and the physical explanations for the phenomenon have been given based on the photonic crystal theory. And then, the features of the PPCs are compared to the corresponding photonic crystals (PCs) through both experiments and simulations. The results show that plasma slabs in PCs can change the band structure and influence the transmission of microwaves, which can be useful to the design of microwaves devices with PPCs.

Experiment and simulation analysis on noise reduction of cylindrical shells with viscoelastic material

In order to solve the problem of mid-low frequency noise reduction in cylindrical shells, the experimental and simulation methods are used to study the noise reduction performance of cylindrical shells with different acoustic covering layers in the mid-low frequency range. Firstly, a cylindrical shell noise reduction experimental device was established, the experiment for cylindrical shell structure and laying a viscoelastic material shell structure were carried out. Acoustic commercial software (LMS Virtual. Lab) was used to establish a finite element model for simulation analysis, the numerical results then compared with the experimental results. Finally, the finite element simulation was applied to study the noise response in the cylindrical cavity of lining different materials and the influence of the laying scheme and thickness of the layer. The results show that, in the case of the same laying rate, the oblique laying has a better noise reduction effect and the amount of noise reduction increases as the laying thickness increases. Under a constant thickness of the foam-butyl rubber, as the proportion of butyl rubber increases, the noise reduction per unit thickness increases, while the noise reduction per unit mass decreases.

Discharge current enhancement in inertial electrostatic confinement fusion by impulse high magnetic field

Effect of strong pulsed magnetic field on the discharge behavior of a cylindrical inertial electrostatic (IEC) device has been investigated both theoretically and experimentally. By applying strong pulsed magnetic field in a new fabricated miniature cylindrical IEC device equipped with Inductively Coupled Plasma (ICP), discharge current amplifications were observed at ordinary pressures as well as low pressure ICP-assisted operational regime with deuterium gas. The obtained results indicate the evidence for significant amplification of discharge current up to more than one hundred times. Since the neutron production rate has been previously proven to be linearly dependent on the discharge current, then this study might open new investigations for probable increment of fusion reaction rates in IEC devices with additional strong magnetic field.

Estimation of doping in junctionless transistors through dc characteristics

In this work, a new technique has been developed to extract the doping (Nd) of a junctionless (JL) transistor using dc analysis i.e. transfer characteristics. The proposed method utilises the evaluation of bulk mobility (μbulk) by averaging the values of transconductance (gm) between the limits of threshold (Vth) and flatband (Vfb) voltages of a junctionless device to account for bulk conduction, which can be subsequently used to extract the doping from the volume current. Results show that the extracted doping values are very close to the doping used in the simulations. The methodology is applied to planar (single gate and double gate) as well as non-planar i.e. triple gate and cylindrical nanowire devices. Impact of gate length downscaling and series resistance is also investigated. The validity of the developed approach to predict the doping is also verified through the experimental data published in the literature. The work showcases the potential of a new and relatively simpler approach to estimate the doping of a junctionless transistor by utilising dc characteristics and avoiding the capacitance measurements that often require careful de-embedding techniques.

Experimental and numerical study of air entrainment into a louvered conical IRS device and comparison with existing IRS devices

An experimental study was carried out on a laboratory-scale louvered conical infrared suppression (IRS) device to predict the air entrainment into it. A comparison has been made between the louvered conical, conical and the cylindrical IRS device based on the air entrainment ratio with increasing geometric ratio. A numerical study on the flow domain was also performed by solving the continuity and Navier-Stokes equations using the k-epsilon turbulence model. The air entrainment was compared with the experimental data and a good match was found. The results showed that the louvered conical IRS device outperforms the other two IRS devices significantly when the geometric ratio exceeds a value of 1.4. The mass entrainment of the ambient air was maximum when four louvered funnels at optimum overlap were used. Increasing or decreasing the number of funnels from this value lowers the air entrainment. In the analysis, it was also found that the nozzle protrusion adversely affects the air entrainment and hence for getting the highest entrainment, the nozzle was flush with the lower opening of the bottom most funnel. The funnel overlap also acts as an important parameter as far as the rate of air entrainment is concerned. The air entrainment through the IRS device was found to be maximum when the non-dimensional funnel overlap height (Hoverlap/Dnz) was kept at 8. The mass entrainment rate was found to increase linearly with the nozzle exit Reynolds number in the range of parameters for which the study was undertaken.

Combined methods of moment vectors and Stokes parameters to analyze tomographic image of plasma turbulence

Plasma turbulence tomography is now working to show a two dimensional structure and dynamics of plasma turbulence in a cylindrical plasma device, PANTA. A new method, the Stokes parameter analysis on moment vectors, is being developed to treat the image of plasma turbulence and extract hidden characteristics of polarization or rotation of spatial patterns created in turbulent plasmas. The article presents the explanation of the method and the application results obtained from a PANTA plasma.

Monitoring of air tunnels in a cylindrical storage device using ECT tomography

This article focuses on the monitoring of air tunnels in sand, which in common practice are characterised as flow disturbances in the flow of bulk materials inside storage devices, hoppers, silos etc. In this case air tunnels are monitored by the ECT (Electrical Capacitance Tomography) method. The basic principle of the ECT tomographic method is the measurement of permittivity of a measured non-conducting medium. The results gained by an ECT device are then compared with the real, precisely defined measured state. The measured results show that the monitoring of flow disturbances in storage devices using ECT is a new method which does not use optical methods during measurement.