Configuration In Conjunction Research Articles

A Numerical Investigation on the Behavior of Electrons in the Bullet in the Atmospheric- Pressure Argon Plasma Jet

Electrons are generated abundantly in the plasma jet and play an active role in the mass transfer of reactive species in the aqueous solution in plasma medicine. Such an importance requires knowledge of the behavior of electrons in the plasma jet. The objective of this work is to understand the electron behaviors in the bullet in the plasma jet, including the angle spectrum of electrons (ASEs) and the related energy spectrum, so as to have an insight into those electrons which most probably interact with the target. The numerical modeling based on a needle–plate discharge configuration in conjunction with a 1-D Particle-in-Cell Monte-Carlo Collision (PIC-MCC) simulation method was used to achieve this task. The scattering angle of electron in the bullet is described using the angle between the electron scattering direction and the bullet propagation direction. The ASE in the bullet is close to a sinusoidal distribution. As the bullet propagates, the temporal evolution of ASE indicates that relatively more electrons in the bullet are scattered into the angle range below 90°, but at any moment when the propagating bullet is close to the target, ASE in the bullet generally remains unchanged. In addition, relatively less electrons in the bullet are scattered into the angle range below 90° due to the increase of the applied voltage amplitude. For the considered voltage amplitudes below 7 kV, the number of electrons in the angle range below 90° is within 47% of electrons in the bullet and, in these electrons, the proportion of non-subionization electrons reaches about 12%. These results may be taken into consideration in investigating the mass transfer of reactive species in plasma medicine.

Two signs indicative of successful access in nuclear medicine cerebrospinal fluid diversionary shunt studies.

Successful shunt access is the first step in a properly performed nuclear medicine cerebrospinal fluid (CSF) shunt study. To determine the significance of the radiotracer configuration at the injection site during initial nuclear medicine CSF shunt imaging and the lack of early systemic radiotracer activity as predictors of successful shunt access. With Institutional Review Board approval, three nuclear medicine physicians performed a retrospective review of all consecutive CSF shunt studies performed in children at our institution in 2015. Antecedent nuclear medicine CSF shunt studies in these patients were also assessed and included in the review. The appearance of the reservoir site immediately after radiotracer injection was classified as either figure-of-eight or round/ovoid configuration. The presence or absence of early systemic distribution of the tracer on the 5-min static images was noted and separately evaluated. A total of 98 nuclear medicine ventriculoperitoneal CSF shunt studies were evaluated. Figure-of-eight configuration was identified in 87% of studies and, when present, had 93% sensitivity, 78% specificity, 92% accuracy, 98% positive predictive value (PPV) and 54% negative predictive value (NPV) as a predictor of successful shunt access. Early systemic activity was absent in 89 of 98 studies. Lack of early systemic distribution of the radiotracer had 98% sensitivity, 78% specificity, 96% accuracy, 98% PPV and 78% NPV as a predictor of successful shunt access. Figure-of-eight configuration in conjunction with the absence of early systemic tracer activity had 99% PPV for successful shunt access. Figure-of-eight configuration at the injection site or lack of early systemic radiotracer activity had moderate specificity for successful shunt access. Specificity and PPV significantly improved when both signs were combined in assessment.

Mass attenuation coefficients of several bio-adhesive based oil palm particleboards at 16.59-25.26 keV photon energies

Particleboards made of oil palm with addition of polylactic acid (PLA), starch, and fish oil were fabricated with target density of 1.0 g/cm3. The mass attenuation coefficients of the particleboards were measured using x-ray fluorescence (XRF) configuration in conjunction with niobium, molybdenum, palladium and tin metal plates that provided Kα1 photon energies between 16.59 and 25.26 keV. The results were compared to the calculated value of water using XCOM. The results showed that all particleboards having mass attenuation coefficients near to the value of water with the mass attenuation coefficient different less than 0.25. The method of fabrication did not give significant different to the mass attenuation coefficients of the particleboards. The results had indicated the potential of bio-adhesive based palm oil particleboards to be developed as phantoms for low energy photons.

Design of an enhanced wideband energy harvester using a parametrically excited array

A wideband energy harvester has been designed, fabricated, and tested based on an array of four parametrically excited cantilever beams; the cantilever beams carry a tip mass at their free end. Piezoelectric transduction has been used to convert between the mechanical and electrical domains. An array configuration in conjunction with parametric excitation generated an enhanced bandwidth of the device (at low frequencies); furthermore, each piezoelectric beam displayed nonlinear dynamical behaviour due to geometric extensibility at the centreline—this behaviour was used to further increase the bandwidth of the energy harvester. An electrodynamic shaker has been used to parametrically excite the energy harvester, and the corresponding voltage of each piezoelectric beam has been measured. It was observed the energy harvester displayed eight resonance peaks that are within close proximity of each other, particularly, for low frequency applications (below 13 Hz); each piezoelectric beam generated substantial power (in the milli-Watt range).

Three new species of Carychium O.F. Müller, 1773 from the Southeastern USA, Belize and Panama are described using computer tomography (CT) (Eupulmonata, Ellobioidea, Carychiidae).

Three new species of the genus Carychium O.F. Müller, 1773, Carychium hardiei Jochum & Weigand, sp. n., Carychium belizeense Jochum & Weigand, sp. n. and Carychium zarzaae Jochum & Weigand, sp. n. are described from the Southeastern United States, Belize and Panama, respectively. In two consecutive molecular phylogenetic studies of worldwide members of Carychiidae, the North and Central American morphospecies Carychium mexicanum Pilsbry, 1891 and Carychium costaricanum E. von Martens, 1898 were found to consist of several evolutionary lineages. Although the related lineages were found to be molecularly distinct from the two nominal species, the consequential morphological and taxonomic assessment of these lineages is still lacking. In the present paper, the shells of these uncovered Carychium lineages are assessed by comparing them with those of related species, using computer tomography for the first time for this genus. The interior diagnostic characters are emphasized, such as columellar configuration in conjunction with the columellar lamella and their relationship in context of the entire shell. These taxa are morphologically described and formally assigned their own names.

Time-resolved image plane off-axis digital holography

In this work, we demonstrate off-axis image-plane digital holography for measuring ultrafast processes with high temporal resolution. The proposed image-plane holographic configuration in conjunction with numerical post-processing procedures allows us to neglect the walk-off effect in the off-axis arrangement by synthesizing spatial phase distribution with the whole field of view from separate fragments and to increase the spatial resolution by means of a telecentric system with adjustable magnification. We have analyzed temporal resolution taking into account all dispersing elements that increase the duration of the pulses being propagated through the optical setup. The technique was approved with experiment on measuring the dynamics of the refractive index, induced by laser filamentation in air.

Numerical Study on an Airflow Field of a Reticle Stocker with a Moving Crane in a Mini-Environment

This study numerically investigates the effects of a moving crane and airflow on contaminant removal efficiency of various reticle box coverage sequences in a stocker. The analyzed characteristics of flow patterns are used to protect the reticles from contaminants, without altering their internal component configuration in conjunction with the aim of cost-savings. A finite volume method was applied in a numerical analysis using computational fluid dynamics software, ANSYS Fluent. To simulate actual operating conditions, the effects of inlet velocity of clean air and crane movement speed on contaminant removal efficiency (CRE) are considered, and a particle release technique is analyzed to determine contaminant concentrations in the stocker. The results show that a higher airflow rate leads to a better contaminant removal efficiency in the stocker. For the various arrangements of reticle boxes in the stocker, the symmetric coverage sequence provides the most satisfactory contaminant removal rate. An optimal inlet airflow velocity of 0.12 m/s is obtained based on the CRE distribution. In addition, the airflow distributions indicate that a vortex is induced by the air flow through a solid boundary; thus, a higher inlet airflow velocity results in a small vortex that also benefits the CRE. The results also demonstrate that a high crane movement speed causes a large reverse flow region at the bottom that also induces a long wake behind the crane, into which particles are easily drawn.

Robust Master-Slave Synchronization of Neuronal Systems

The desire to understand physiological mechanisms of neuronal systems has led to the introduction of engineering concepts to explain how the brain works. The synchronization of neurons is a central topic in understanding the behavior of living organisms in neurosciences and has been addressed using concepts from control engineering. We introduce a simple and reliable robust synchronization approach for neuronal systems. The proposed synchronization method is based on a master-slave configuration in conjunction with a coupling input enhanced with compensation of model uncertainties. Our approach has two nice features for the synchronization of neuronal systems: (i) a simple structure that uses the minimum information and (ii) good robustness properties against model uncertainties and noise. Two benchmark neuronal systems, Hodgkin-Huxley and Hindmarsh-Rose neurons, are used to illustrate our findings. The proposed synchronization approach is aimed at gaining insight into the effect of external electrical stimulation of nerve cells.

Transport in fullerene device coupled to Cu, Ag and Au electrodes

ABSTRACTWe present an ab initio approach of the electronic transport through a single molecular junction based on C20 fullerene. The electronic properties of a single molecular junction constrained within two semi-infinite metallic electrodes are largely affected by the choice of electrode material. The two-probe device formed by the mechanically control break technique has been modelled with three distinct electrode materials from group IB of the periodic table, namely copper, silver and gold. The quantum characteristics of these mechanically stable devices are obtained by utilising first-principle density functional theory together with non-equilibrium green function method. We evaluate the quantum characteristics, namely density of states, transmission spectrum, energy levels, current and conductance, which essentially determine the behaviour of a molecule linked to different electrodes. Our investigation concludes that copper, silver and gold electrode configuration in conjunction with C20 fullerene behaves as metallic, non-metallic and semi-metallic in nature, respectively.

Sodium MRI of the human heart at 7.0 T: preliminary results.

The objective of this work was to examine the feasibility of three-dimensional (3D) and whole heart coverage (23)Na cardiac MRI at 7.0 T including single-cardiac-phase and cinematic (cine) regimes. A four-channel transceiver RF coil array tailored for (23)Na MRI of the heart at 7.0 T (f = 78.5 MHz) is proposed. An integrated bow-tie antenna building block is used for (1)H MR to support shimming, localization and planning in a clinical workflow. Signal absorption rate simulations and assessment of RF power deposition were performed to meet the RF safety requirements. (23) Na cardiac MR was conducted in an in vivo feasibility study. 3D gradient echo (GRE) imaging in conjunction with Cartesian phase encoding (total acquisition time T(AQ) = 6 min 16 s) and whole heart coverage imaging employing a density-adapted 3D radial acquisition technique (T(AQ) = 18 min 20 s) were used. For 3D GRE-based (23)Na MRI, acquisition of standard views of the heart using a nominal in-plane resolution of (5.0 × 5.0) mm(2) and a slice thickness of 15 mm were feasible. For whole heart coverage 3D density-adapted radial (23)Na acquisitions a nominal isotropic spatial resolution of 6 mm was accomplished. This improvement versus 3D conventional GRE acquisitions reduced partial volume effects along the slice direction and enabled retrospective image reconstruction of standard or arbitrary views of the heart. Sodium cine imaging capabilities were achieved with the proposed RF coil configuration in conjunction with 3D radial acquisitions and cardiac gating. Cardiac-gated reconstruction provided an enhancement in blood-myocardium contrast of 20% versus the same data reconstructed without cardiac gating. The proposed transceiver array enables (23)Na MR of the human heart at 7.0 T within clinical acceptable scan times. This capability is in positive alignment with the needs of explorations that are designed to examine the potential of (23)Na MRI for the assessment of cardiovascular and metabolic diseases.

Active sound radiation control of a submerged piezocomposite hollow sphere

A spatial state-space approach based on the linear three-dimensional exact piezoelasticity theory along with the Helmholtz equations for the internal/external acoustic domains are employed to describe the coupled vibroacoustic response of an arbitrarily thick, spherically isotropic, functionally graded, radially polarized piezolaminated hollow sphere, immersed in and filled with ideal compressible fluids, and under the actions of arbitrary (non-axisymmetric) distributed time-harmonic transverse mechanical excitations at its inner and/or outer boundaries. A frequency domain subspace–based identification technique is applied to estimate the coupled fluid-structure dynamics of the system in the controller design stage. Subsequently, a standard linear quadratic Gaussian optimal controller is synthesized and simulated based on the identified model, and the optimal control input voltages for suppressing the sensor output voltage (total radiated power) of the submerged sphere are calculated for selected weighting parameters associated with the system response and control input. Numerical simulations establish the effectiveness of the selected (partial/full) sensor/actuator configuration in conjunction with the adopted control strategy for attenuating the predicted sound radiation response of an air-filled, water-submerged, sandwich piezocomposite (PZT4/steel/PZT4) sphere, in both frequency and time domains. Also, the trade-off between dynamic performance and control effort penalty is examined for impulsive and Gaussian random external mechanical disturbances. Furthermore, the effect of piezoelectric material gradient variation on sound radiation control performance of the smart piezocomposite structure is briefly discussed. The validity of the acousto-elastic model is demonstrated by use of a commercial finite element package as well as by comparison with the data available in the literature.

Non-destructive technique for broadband characterization of carbon nanotubes at microwave frequencies

This paper presents a broadband microwave non-destructive technique for characterization of carbon nanotubes (CNTs). Typically, commercially available carbon nanotubes are powder-like samples and, therefore, in this paper, a broadband characterization technique to extract electrical conductivity of powder materials is developed. The technique uses a microstrip line configuration in conjunction with a cavity resonator technique. The electrical conductivity of CNTs is extracted from the measured attenuation in the signal response (|S21|dB) for the microstrip configuration with a signal trace made of copper and a ground plane filled with CNT samples. A resonant cylindrical cavity is also used in the measurement process to help determine a correction factor for the surface roughness of the CNT microstrip ground plane. A novel method to take attenuation due to surface roughness into account to determine conductivity of CNTs is introduced. Experimental and numerical verification of the proposed method is provided. The method developed in this work provides a cost-effective solution where significant amount of time and cost are reduced in the sample preparation process. Measurement results for the electrical conductivity of single-walled CNTs and multi-walled CNTs are presented.

Structural elucidation of low abundant metabolites in complex sample matrices

Identification of metabolites is a major challenge in biological studies and relies in principle on mass spectrometry (MS) and nuclear magnetic resonance (NMR) methods. The increased sensitivity and stability of both NMR and MS systems have made dereplication of complex biological samples feasible. Metabolic databases can be of help in the identification process. Nonetheless, there is still a lack of adequate spectral databases that contain high quality spectra, but new developments in this area will assist in the (semi-)automated identification process in the near future. Here, we discuss new developments for the structural elucidation of low abundant metabolites present in complex sample matrices. We describe how a recently developed combination of high resolution MS multistage fragmentation (MSn) and high resolution one dimensional (1D)-proton (1H)-NMR of liquid chromatography coupled to solid phase extraction (LC–SPE) purified metabolites can circumvent the need for isolating extensive amounts of the compounds of interest to elucidate their structures. The LC–MS–SPE–NMR hardware configuration in conjunction with high quality databases facilitates complete structural elucidation of metabolites even at sub-microgram levels of compound in crude extracts. However, progress is still required to optimally exploit the power of an integrated MS and NMR approach. Especially, there is a need to improve and expand both MSn and NMR spectral databases. Adequate and user-friendly software is required to assist in candidate selection based on the comparison of acquired MS and NMR spectral information with reference data. It is foreseen that these focal points will contribute to a better transfer and exploitation of structural information gained from diverse analytical platforms.

Development of Yttrium Stabilized Zirconia (YSZ) diffusion barrier coatings for mitigation of Fuel–Cladding Chemical Interactions

Fuel–Cladding Chemical Interactions (FCCIs) in a nuclear reactor occurs due to thermal and radiation enhanced inter-diffusion between the cladding and fuel materials. This can have the detrimental effects of reducing the effective cladding wall thickness and the formation of low melting point eutectic compounds. Deposition of thin diffusion barrier coatings in the inner surface of the cladding can potentially reduce or delay the onset of FCCI. This study examines the feasibility of using nanofluid-based electrophoretic deposition (EPD) process to deposit coatings of Yttrium Stabilized Zirconia (YSZ) as the diffusion barrier coating. The deposition parameters, including the nanofluid solvent, additive, particle size, current, and voltage were optimized using test flat substrates of T91 ferritic–martensitic steel. A post deposition sintering step was also conducted and optimized to improve the bonding and mechanical integrity of the coating. Diffusion characteristics of the coatings were investigated by diffusion couple experiments using cerium as a fuel fission product responsible for solid state FCCI. These diffusion couple studies performed at 575°C for 100h showed that the YSZ coatings significantly reduced the solid state inter-diffusion between cerium and steel. A heat transfer model was developed to simulate the changes in temperature profile inside the fuel cladding by addition of YSZ coating. It was found that even though the temperature can increase in the coated cladding, the temperature falls below the melting point of uranium and eutectic temperature in Fe–U phase diagram. Using a co-axial configuration in conjunction with the EPD process, YSZ was successfully deposited uniformly on the inner surfaces of 12″ length sections of cladding with 4mm inner diameter. Such a coating is extremely hard to make by conventional coating technologies like thermal spray or vapor deposition.

Heart Sounds Human Identification and Verification Approaches using Vector Quantization and Gaussian Mixture Models

In this paper the possibility of using the human heart sounds as a human print is investigated. To evaluate the performance and the uniqueness of the proposed approach, tests using a high resolution auscultation digital stethoscope are done for nearly 80 heart sound samples. The verification approach consists of a robust feature extraction with a specified configuration in conjunction with Gaussian mixture modeling. The similarity of two samples is estimated by measuring the difference between their negative log-likelihood similarities of the features. The experimental results obtained show that the overall accuracy offered by the employed Gaussian mixture modeling reach up to 85%. The identification approach consists of a robust feature extraction with a specified configuration in conjunction with LBG-VQ. The experimental results obtained show that the overall accuracy offered by the employed LBG-VQ reach up to 88.7%.

10 Gb/s Indoor Optical Wireless Systems Employing Beam Delay, Power, and Angle Adaptation Methods With Imaging Detection

In this paper, we propose a mobile optical wireless system that employs beam delay adaptation, and makes use of our previously introduced beam angle and power adaptation multi-beam spot diffusing configuration in conjunction with an imaging receiver. Our ultimate goal is to improve the bandwidth, reduce the effect of intersymbol-interference, and increase the signal-to-noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise, and mobility. A significant reduction in the delay spread can be achieved compared to a conventional diffuse system (CDS) when an imaging receiver replaces a nonimaging receiver at the room's corner, where the delay spread is reduced from 2.4 ns to about 0.35 ns. Our proposed system, beam delay, angle, and power adaptation in a line strip multibeam spot diffusing configuration (BDAPA- LSMS), offers a reduction in delay spread by a factor of more than 10 compared with only the beam angle and power adaptation LSMS. An increase in channel bandwidth from 36 MHz (CDS) to about 9.8 GHz can be achieved when our methods of beam delay, angle, and power adaptation coupled with an imaging receiver are employed. These improvements enhance our system and enable it to operate at a higher data rate of 10 Gb/s. At a bit rate of 30 Mb/s, our proposed BDAPA-LSMS achieves about 50 dB SNR gain over conventional diffuse systems that employ a nonimaging receiver (CDS). Moreover, our simulation results show that the proposed BDAPA-LSMS at a bit rate of 10 Gb/s achieves about 32.3 dB SNR at the worst communication path under the presence of background noise and mobility while achieving a bit error rate below 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> .

Performance Evaluation of 5 Gbit/s and 10 Gbit/s Mobile Optical Wireless Systems Employing Beam Angle and Power Adaptation with Diversity Receivers

Over the last two decades, indoor optical wireless (OW) systems have operated typically at 30 Mbit/s to 155 Mbit/s. Here, we propose and evaluate for the first time a mobile OW system that operates at 5 Gbit/s and 10 Gbit/s. The improvements in data rates and channel bandwidth are achieved through the introduction of three approaches: angle diversity, beam angle and beam power adaptation. We propose a mobile OW system that employs beam angle and beam power adaptation in a line strip multibeam spot diffusing system configuration in conjunction with an angle diversity receiver (APA-LSMS) to mitigate the degradation due to ambient light noise, multipath dispersion and mobility. The performance of our proposed system was investigated through channel and noise modelling. Our results show that the proposed APA-LSMS at a bit rate of 30 Mbit/s achieves about 45 dB signal-to-noise ratio (SNR) gain over a power adaptive line strip multibeam system (PA-LSMS) and offers 60 dB SNR gain over a conventional diffuse system (CDS) at a 6 m horizontal separation between the transmitter and the receiver. The SNR is independent of the transmitter location and when our methods (angle diversity, beam angle and beam power adaptations) are implemented, the SNR can be maximized at the receiver for every transmitter location. The results show an increase in channel bandwidth from 36 MHz (CDS) to approximately 7.2 GHz in our proposed system (APA-LSMS). These improvements enhance our system and enable it to operate at higher data rates of 5 Gbit/s and 10 Gbit/s.

A Comparative Thermal Analysis of Slot-Entry and Hole-Entry Hybrid Journal Bearings Lubricated With Non-Newtonian Lubricant

The effect of viscosity variation due to temperature rise and non-Newtonian behavior of the lubricant on the performance of hole-entry and slot-entry hybrid journal bearings system is the focus of this investigation. The performance characteristics of nonrecessed hybrid journal bearings operating with different flow controlling devices, i.e., constant flow valve, capillary, orifice, and slot restrictors, have been compared. Finite element method has been used to solve the Reynolds equation governing the flow of lubricant in the bearing clearance space along with the restrictor flow equation, energy equation and conduction equation using suitable iterative technique. The non-Newtonian lubricant has been assumed to follow the cubic shear stress law. The results indicate that variation in viscosity due to rise in temperature and non-Newtonian behavior of the lubricant affects the performance of nonrecessed hybrid journal bearing system quite significantly. The results further indicate that bearing performance can be improved by selecting a particular bearing configuration in conjunction with a suitable compensating device.

MULTIWALLED CARBON NANOTUBE-BASED AROMATIC HYDROCARBON SENSOR USING ELECTRONIC DIPOLE SPECTROSCOPY

A novel electronic spectroscopy technique based on dipole-dipole interactions for the identification of chemical analytes has been developed. This technique is based on the measurement of the charge transfer of chemical analytes to a multiwalled carbon nanotube mat-based sensing system. This technique was used for the identification of three aromatic hydrocarbons, namely, benzene, toluene, and xylene, at 100 parts-per-billion concentration. This technique was evaluated with multiwalled carbon nanotube mats for rapid, reliable, and robust identification of the three chemicals that belong to the same genre. The technique involves the identification of electronic spectral signatures of these chemicals using frequency domain analysis of the voltage signals generated by the binding of the chemical analytes onto the multiwalled carbon nanotube mat surfaces. This technique has the potential for rapid and accurate identification of multiple chemical analytes in a multiplexed fashion using a single-sensor device. In addition, this particular device configuration in conjunction with the electronic dipole spectroscopy results is a powerful lab-on-a-chip device for chemical and biological sensing applications.

Constrained sessile drop as a new configuration to measure low surface tension in lung surfactant systems

Existing methodology for surface tension measurements based on drop shapes suffers from the shortcoming that it is not capable to function at very low surface tension if the liquid dispersion is opaque, such as therapeutic lung surfactants at clinically relevant concentrations. The novel configuration proposed here removes the two big restrictions, i.e., the film leakage problem that is encountered with such methods as the pulsating bubble surfactometer as well as the pendant drop arrangement, and the problem of the opaqueness of the liquid, as in the original captive bubble arrangement. A sharp knife edge is the key design feature in the constrained sessile drop that avoids film leakage at low surface tension. The use of the constrained sessile drop configuration in conjunction with axisymmetric drop shape analysis to measure surface tension allows complete automation of the setup. Dynamic studies with lung surfactant can be performed readily by changing the volume of a sessile drop, and thus the surface area, by means of a motor-driven syringe. To illustrate the validity of using this configuration, experiments were performed using an exogenous lung surfactant preparation, bovine lipid extract surfactant (BLES) at 5.0 mg/ml. A comparison of results obtained for BLES at low concentration between the constrained sessile drop and captive bubble arrangement shows excellent agreement between the two approaches. When the surface area of the BLES film (0.5 mg/ml) was compressed by about the same amount in both systems, the minimum surface tensions attained were identical within the 95% confidence limits.