Coaxial Type Research Articles

Safety and efficacy of different transplant kidney biopsy techniques: comparison of two different coaxial techniques and needle types.

Percutaneous ultrasound-guided renal biopsy is essential for diagnosing medical renal disorders in transplant kidneys. A variety of techniques have been advocated. The purpose of this study is to evaluate the safety and efficacy of two different coaxial techniques and biopsy devices. This single-center dual-arm, observation study cohort included 1831 consecutive transplant kidney biopsies performed over a 68-month period. Two coaxial techniques were used, distinguished by whether the 17 gauge (G) coaxial needle was advanced into the renal cortex (intracapsular technique; IC) or to the edge of the cortex (extracapsular technique; EC). One of two needle types could be used with either technique: an 18G side-cutting (Bard Max-Core or Mission) or an 18G end-cutting (Biopince Ultra) needle. In all cases, the cortical tangential technique was used to reduce the risk of central artery transgression and unnecessary medullary sampling. Patients were monitored for 30 days post-procedurally and complications were evaluated using the SIR adverse event classification. Of the 1831 patients included in the study cohort, 13 suffered severe bleeding complications requiring operative intervention. Of these patients, 8 underwent biopsy with side-cutting needle and IC, 2 with side-cutting needle and approach not specified, 2 with end-cutting needle and IC, and 1 with end-cutting needle and EC. There was no statistically significant difference in the risk of bleeding complications between different coaxial techniques and needle types. However, there was a significantly increased chance of inadequate sampling when comparing the side-cutting needle (1.0%) to the end-cutting needle (0.1%). Transplant kidney biopsy performed with two different coaxial techniques and needle types did not show differences in bleeding complications. There is an increased risk of inadequate sampling when using side-cutting relative to end-cutting biopsy devices.

Research on development and quantitative control preparation technology of array-type microfine bubbles generator

In traditional wastewater treatment, ozone injection efficiency is low. There is a need for the quantitative preparation of ozone-based microfine bubbles to balance bubble stability and ozone reactivity. To address this, we developed coaxial and T-type ozone-based microfine bubble generators and conducted experiments to compare their bubble production effects. The more effective generator was then compared with the traditional aeration method. The results indicate the following: 1. The coaxial type is more effective in producing ozone-based microfine bubbles. 2. The bubbles produced by the coaxial type have an average diameter of 0.2–0.4 mm and a residence time of ∼2 min, meeting microfine bubble standards. Experimental data analysis shows compliance with the force process and bubble growth mechanism under coaxial flow, meeting the requirements for quantitative and controllable ozone-based microfine bubble production. 3. Ozone bubbles from the coaxial method surpass those from traditional aeration in volume and concentration. More than 99.73% are microfine bubbles, with an ozone concentration of ∼84.5%. 4. The coaxial method more effectively reduces COD values in water, contributing to efficient wastewater treatment. This research presents new avenues for efficient sewage treatment.

Comparative Analysis of Influencing Factors on Heat Extraction Performance of Multi-Type Shallow Borehole Heat Exchangers

In this paper, the influence of design parameters and geological parameters on the heat extraction capacity of common coaxial type, single U-type, and double U-type borehole heat exchangers(BHEs) in shallow ground source heat pump system is analyzed, and the heat extraction performance of different types of BHEs is further compared. The results show that with the increase in borehole depth and ground temperature gradient, the outlet temperature of the three types increases at the end of the heating season, and the single U-type BHE increases most significantly. The increase in inlet flow rate will decrease the outlet temperature of the three BHEs, and the U-type is the most obvious decrease. The increase in inlet temperature will reduce the temperature difference between inlet and outlet of the three types BHEs. Given the same design parameters, coaxial-type BHE obtains the maximum heat.

Analyzing the Automatic Power Level Control Effect of a Signal Generator in RF Power Sensor Calibration by a Direct Comparison Transfer Method and a Millimeter Wave Application.

Most calibration laboratories prefer the Direct Comparison Transfer Method (DCTM) for a reliable and accurate calibration of power sensors in the radio frequency (RF) scope. Most studies suggest using this calibration method, with its automatic power level control (APLC) of RF signal generators. The APLC is preferred to keep the output power level of the signal generator the same, while the power sensor is calibrated and the reference power sensor is connected to the measurement system. The known APLC mechanisms are also explained for the DCTM, and a comparison of the calibration factor values carried out with and without the automatic power level control process in the DCTM is also given in this study. RF power sensor calibrations with coaxial and waveguide connector types are examined with DCTM in this study as well. This study shows that the DCTM, unless with APLC, should be applied for the waveguide power sensor's calibration at millimeter wave frequencies.

Numerical investigation on non-linear streaming effects in a two-stage coaxial pulse tube cryocooler

Stirling pulse tube cryocoolers (PTC) are widely used in aerospace applications for the cooling of infrared sensors and for filtering background thermal noise in the astro-imaging devices, etc. Present investigation aims to use numerical methods to demonstrate the nonlinear fluid flow, heat transfer, and vortex generation phenomena in a two-stage coaxial type inertance pulse tube cryocooler. The numerical simulation is conducted using commercially available Fluent® code for both single-stage and multi-stage configurations to show nonlinear processes with varying heat load conditions. It has been noticed that the width of the vortex produced inside the pulse tube grows with an increase in heat load capacity. This undesirable flow conditions yields an adverse effect in the cooling behavior and reduces overall performance of cryocooler with higher heat load. Additionally, streamlines, stream function, pressure and temperature variation plots are given for both stages with different heat load capacity to substantiate our results.

Estimation of transfer factor from soil to cassava in Ethiope East, Delta State, Nigeria

Cassava is a very important staple food crop in Delta state. The aim of this research is to assess the activity concentration level and determine the transfer factor of radionuclide from soil to cassava in Ethiope Local Government Area of Delta state, Nigeria. The activity concentration of 40K, 238U and 232Th in soil and cassava samples collected from the study area were analysed using gamma spectrometry. A lead-shielded 3 x 3 inch coaxial type Sodium Iodide Thallium [NaI(TI)] doped detector crystal (Model No. 802 series, Canberra Inc.) coupled to a Canberra series multichannel Analyzer (MCA) (Model N0.1104) through a preamplifier was used. The results of the activity concentration in soil samples indicate that, 40K has the highest mean activity concentration ((38.66 ± 3.69) BqKg−1) with the highest value ((62.47 ± 5.67) BqKg−1) recorded at E2. The mean activity concentrations of 238U and 232Th are 3.65 ± 0.90 BqKg−1 and 0.46 ± 0.05 BqKg−1respectively. The peak values of 238U and 232Th are 5.07 ± 1.17 BqKg−1 and 0.98 ± 0.11 BqKg−1. From cassava, 40K varies from 75.06 to 200.08 BqKg−1 with the highest mean activity concentration of 99.62 ± 8.32 BqKg−1 and 200.08 ± 14.90 BqKg−1 as the highest value noted at C5. The mean activity concentrations of 238U and 232Th are 3.89 ± 0.93 BqKg−1 and 0.81 ± 0.09 BqKg−1 respectively. The maximum values of 238U and 232Th determined from the computation from cassava samples are 11.10 ± 2.48 BqKg−1 and 1.70 ± 0.18 BqKg−1. The results of this study show that the activity concentration of 40K, 238U and 232Th in the study area are lower than world average values of 420, 30 and 35 BqKg-1 in soil and cassava respectively, and it is therefore not harmful if consumed. The mean transfer factor of 40K, 238U and 232Th from soil to cassava are 3.12 ± 0.44, 0.95 ± 0.31 and 2.96 ± 0.91 respectively. The range of values of 40K, 238U and 232Th varied as 1.41 to 5.82, BDL to 2.98 and 0.21 to 9.35 correspondingly. Peak values of the TF were noted as 5.82 for 40K at E8, C8, 2.98 for 238U at at E9, C9 and 9.35 for 232Th at E9, C9. The high value of TR is accredited to the richness of the organic matter in the soil. The quick recycling of natural radionuclides through the soil-cassava suggests the presence of an internal cycling that help the build-up of the natural radionuclides.

Assessment of Soil to Cassava Transfer Factor of Radionuclides in Ughelli North Local Government Area, Delta State, Nigeria

Background:
 This research was conducted to estimate the activity concentration level of 40K, 238U and 232Th in soil and cassava and determine the transfer factor from soil to cassava in Ughelli North, Delta State, Nigeria.
 Materials and Methods:
 These were examined using gamma spectrometry and considering a lead-shielded 3 x 3inch coaxial type Sodium Iodide Thallium doped detector.
 Results:
 The mean activity concentrations of 40K, 238U and 232Th are 45.49 ± 4.28 BqKg−1, 3.15 ± 0.77 BqKg−1 and 0.56 ± 0.06 BqKg−1 respectively in soil samples and 134.08 ± 11.59 BqKg−1, 3.89 ± 0.93 BqKg−1 and 0.81 ± 0.09 BqKg−1 correspondingly in cassava samples. The mean transfer factor of 40K, 238U and 232Th from soil to cassava are 3.44 ± 0.75, 1.94 ± 0.32 and 1.34 ± 0.54 respectively. Peak values of the TF were noted as 8.52 for 40K at U18, D18, 25.58 for 238U at U12, D12 and 5.71 for 232Th at U11, D11.
 Conclusion:
 The activity concentration of 40K, 238U and 232Th in the area are lower than the world average values. Consequently, it will not pose any radiological hazard if consumed. The high value of Transfer factor is attributed to the richness of the organic matter in the soil and may indicate high ability to transfer radionuclides in the soil to food crops but from the concentration information, these radionuclides present in the soil are low as well as annual effective doses. There is no radiological risk of ingestion.

Concept of integrating geothermal energy for enhancing the performance of solar stills

Solar stills have been coupled to several preheating systems to increase their productivity, but never before to a borehole exchanger. In this work, a coaxial type borehole exchanger has been integrated with a single basin solar still. Transient and steady-state heat transfer models are presented to assess the behaviour of the combined system for a four-month winter period corresponding to the Urmia Lake region in Iran. Because ground serves as a heat source during winters and a heat sink during summer, integration with a ground exchanger is seen to increase the solar still's productivity for the winter months, by about 126 % for the considered values of parameters. It is also seen that the steady model over calculates the total distillate collected, by about 7 % for ground exchanger integrated still and underestimates it by about 0.2 % for an independent still, respectively. It is observed that larger inner and smaller outer radius of the ground exchanger are desirable. Further, the water mass flow rate is seen to possess an optimal value at which the still's output gets maximized. This work is proposed to be a first step in analysing the usefulness of extracting geothermal energy via a borehole exchanger for desalination application via a solar still.

Rock fragmentation and drilling experiment of electric impulse drilling and structural optimization of electrode bit

Due to the low rate of penetration (ROP) and high cost of natural resource development projects such as oil and gas, and mining, it's urgent to explore some new rock-breaking methods with subversive characteristics for rising ROP. Electric impulse drilling (EID) has attracted widespread attention due to its unique advantages, but its rock-breaking effect is affected by various factors such as the structures of electrode bits, pulse voltage characteristics, liquid medium type, rock type, circulation conditions, and the contact between electrode bit and rocks, etc, leading to the lack of theoretical basis for the design of the electrode bit. Therefore, to more truly reflect the interaction among electrode bits, rocks, and liquid media of EID, this study carried out rock fragmentation and drilling experiment of EID on red sandstone. Firstly, an electrical impulse generator (EIG) with a stable frequency range of 1–5 Hz and a pulse voltage of about 0–80 kV at the load terminal was developed. And an indoor EID and rock fragmentation experimental system was built, then three kinds of electrode bits with typical structures: petal-type (H type), cross-type (S type) and, coaxial type (T type) were designed. Subsequently, the rock fragmentation and drilling experiment of EID was carried out on red sandstone in three liquid media (tap water, deionized water, and hydraulic oil) under the capacitors' charging voltage of 13–17 kV (the load terminal voltage was about 45–60 kV). The general influence law of electrode bit structure, liquid medium type, circulation condition, and pulse voltage on EID was studied. Finally, the electrode bits used in the experiment were evaluated, and suggestions for structural optimization of the electrode bit were put forward based on the experiment. This study is expected to further promote the design of electrode bits and the development of EID technology.

RF conditioning to suppress multipactor discharge for helicon wave current drive in KSTAR

The efficient off-axis non-inductive current drive using auxiliary power is essential for the steady state operation of tokamaks. In previous studies, a helicon wave current drive has been proposed for high beta plasma in several fusion devices, and the 476-MHz radio-frequency (RF) system for the proposed helicon wave has been installed in KSTAR. However, multipactor discharge occurred inside the waveguide system, including the vacuum feedthrough (VFT), and it interrupted the normal RF propagation to plasma. Thus, for successful helicon wave current drive, suppressing the multipactor discharge in the waveguide system, including the 6–1/8″ coaxial type VFT and the newly manufactured helical type traveling wave antenna (TWA) is essential before installation in KSTAR. RF conditioning utilizing a short pulse modulation during a long period helps suppress the multipactor discharge, enabling the 1-MW 476-MHz RF to pass through the entire waveguide system despite the existence of multipactor discharge. Following RF conditioning in VFT with a short pulse modulation, the newly manufactured helical type TWA and VFT for helicon wave current drive have been successfully installed in KSTAR.

Universal rate-dependence in electro-magneto-active polymeric composites

Universal relations are mathematical statements for any material in a given class; the larger the class, the more powerful the universal rule. Such generic relations are to be likely explored in particle-reinforced smart polymeric composites for all possible energy functions and boundary traction forms. Such relations have mainly been developed for an isotropic material class after Ericksen’s seminal work. The present work develops an experimentally validated novel class of coupled universal relations for electro-magneto-active (EMA) polymeric composites under electromagnetic field interaction accounting for the rate-dependent inelastic effect. In such a material class, unless the preferred directions of the material are specified, there would be no general solutions. An EMA polymeric composite material class is of co-axial type if and only if the Cauchy stress (S) and deformation tensor (b) are co-axial for all types of deformation which is preserved in isotropic material class. Co-axiality in the transversely isotropic material class, on the other hand, does not follow the same rule, i.e. (Sb≠bS). Real-world materials, such as soft tissues and smart polymeric composites, do not exhibit co-axiality and instead reveal the dissipation mechanism, necessitating the current study. The proposed theory unifies the pseudo transverse isotropy and rate-dependent phenomena for EMV smart composites in the context of particle reinforcement. Additionally, the current study conducts an experimental investigation to confirm the applicability of the proposed universal relation.

Estimation of an empirical formula for efficiency of a BEGe type detector using machine learning based algorithm

The objective of this study is to establish an empirical formula of full-energy peak efficiency (FEPE), for a Broad Energy High Purity Germanium (BEGe) type detector. FLUKA Monte Carlo-based code is used in this work to simulate radiation transport in the BEGe detector, and FEPE values have been estimated for various gamma energies and wide range of commercially available detector configurations. Then, using machine learning-based non-linear regression models, an empirical formula relating FEPE values with detector configuration (active volume and diameter-to-length ratio) and incident gamma radiation (energy >122 keV) is obtained. The results show that the effect of diameter-to-length ratio on FEPE values cannot be ignored in the case of a BEGe detector, which is not observed in case of coaxial type detectors. At lower energies, the efficiency of the BEGe detector is higher than the coaxial detector due to its large diameter-to-length ratio. This empirical formula can be used to quickly estimate FEPE values and verify nominal geometric parameters provided by the manufacturer.

ЗАЛЕЖНІСТЬ ДИНАМІЧНИХ ХАРАКТЕРИСТИК ІМПУЛЬСНИХ СТРУМІВ ЕЛЕКТРОРОЗРЯДНИХ УСТАНОВОК ВІД ВІДДАЛЕНОСТІ ЇХНЬОГО ТЕХНОЛОГІЧНОГО НАВАНТАЖЕННЯ

The paper investigates the influence of the distant technological load from electric discharge installations (EDIs) with capacitive storage of electricity on the dynamic characteristics of impulse currents in the load. On the basis of experi-mental studies, the peculiarities of changing the dynamic characteristics of EDIs, such as the average rate of rise and fall of their output pulse current during the implementation of volumetric spark dispersion of a layer of metal granules in dielectric liquids between electrodes, were determined. The influence of the length of such types of connecting con-ductors as twisted pair, coaxial cable, and litzendraht with bifilar winding of current-carrying conductors on the output dynamic characteristics of the EDI was analyzed. A significant influence of the type of connecting conductors of con-siderable length on the indicated characteristics has been established, especially in the case of a low-inductance of the load circuit of the EDI. It is substantiated that when the technological load is significantly distant (several meters) from the EDI, it is quite appropriate to use power cables with solid polymer electrical insulation as connecting conductors of the coaxial type. Ref. 10, fig. 2, tables 2.

Wear-Induced Attenuation on Transmission Lines and Their Causes

In this paper, the radio frequency (RF) behavior of mechanically stressed coaxial and for the first time also twisted-pair transmission lines is investigated over their service life. The main goal is to enable predictive maintenance for cables in moving applications and avoid preventive replacement. This also reduces the use of high-cost resources. For this purpose, stranded and solid-core variants of coaxial and twisted-pair type cables are mechanically loaded on the two-pulley apparatus according to EN 50396. Their RF transmission (S21) behavior is measured using a vector network analyzer and presented over bending cycles. For the first time, the phase response of mechanically loaded transmission lines is evaluated with respect to their service life. Two significant causes for the increasing attenuation and altered phase response are identified: breakage in foil screen and increasing surface roughness on the copper conductors. The identified causes are supported with literature evidence. Through measurements and theoretical calculations, it is proven that the phase is much more suitable for an assessment of the remaining service life than the amplitude. The findings can be used to implement a cable monitoring system in industrial environments which monitors the lines in-situ and reminds the user to replace them, whenever a certain wear-level is reached.

A novel methodology to characterize LGA packaged GaN power transistors using a mother/daughter board configuration for the reliability qualification in the mild hybrid applications

The Gallium Nitride GaN based power switching device EPC2206 has a Land Grid Array (LGA) packaging with a pitch between pads of 400 μm. This low pitch does not facilitate transistor connection on a test vehicle in the context of aging tests where the component must undergo repetitive sequences of I(V) and C(V) characterizations, threshold voltage, leakage currents and then repetitive stress. Thus, the purpose of this paper is to adapt this encapsulated power switching device for coaxial or coplanar type measurements and to look for the best configuration to move this transistor from one test bench to another by using an adaptation system on a printed circuit board (PCB). To choose the best performances of three adaptation system configurations, this paper presents, on the one hand, an experimental study on I(V) characterization, threshold voltage Vth, drain leakage current Idss, gate leakage current Igss. On the other hand, a series of measurements of these different characteristics was carried out on the three EPC2206 connection configurations to validate the reproducibility of the measurements.

Numerical Study on the Long-Term Performance and Load Imbalance Ratio for Medium-Shallow Borehole Heat Exchanger System

To contribute to the goal of carbon neutralization, the closed-loop borehole heat exchanger system is widely applied to use geothermal energy for building cooling and heating. In this work, a new type of medium-shallow borehole heat exchanger (MSBHE) is proposed, which is coaxial type and has a depth range between 200 m to 500 m. To investigate the long-term performance of MSBHE in the area with unbalanced cooling and heating load of buildings and the sustainable load imbalance ratio under different design parameters, a comprehensive numerical model is established. The results show that the drilling depth significantly influences the sustainable load imbalance ratio of MSBHE. As the drilling depth is increased from 200 m to 500 m, the load imbalance ratio of the MSBHE increases from 20.76% to 60.29%. In contrast, the load imbalance ratio is always kept at the same level with different inlet velocities and operation modes. Furthermore, in a 9-MSBHE array system, the heat exchanger located in the middle of the array has the lowest load imbalance ratio of 48.97%, which is 15.98% lower than the borehole in the edge location. This is caused by the significant influence of the shifted-load phenomenon among MSBHEs in an array system. The findings of the work imply that this newly proposed MSBHE can sustain a notable load imbalance ratio, which is particularly applicable to the areas with a strong imbalance of annual building load.

Fast and Accurate 2D Analytical Subdomain Method for Coaxial Magnetic Coupling Analysis

Magnetic couplings (MCs) enable contactless speed/torque transmission via interactions between the magnetic fields of permanent magnets (PMs) rather than a physical mechanical connection. The contactless transmission of mechanical power leads to improvements in terms of efficiency and reliability due to the absence of wear between moving parts. One of the most common MC topologies is the coaxial type, also known as the radial configuration. This paper presents an analytical tool for the accurate and fast analysis of coaxial magnetic couplings (CMCs) using a two-dimensional subdomain approach. In particular, the proposed analytical tool resolves Laplace’s and Poisson’s equations for both air-gap and PM regions. The tool can be used to evaluate the impact of several design parameters on the performance of the CMC, enabling quick and accurate sensitivity analyses, which in turn guide the choice of design parameters. After discussing the building procedure of the analytical tool, its applicability and suitability for sensitivity analyses are assessed and proven with the analysis of a fully parameterized CMC geometry. The accuracy and the computational burden of the proposed analytical tool are compared against those of the finite element method (FEM), revealing faster solving times and acceptable levels of precision.

The effect of fibers under compression on the simple shear response of a soft unidirectional fiber-reinforced composite

The aim of this work is to investigate the mechanical behavior of a soft matrix reinforced by a single family of parallel fibers subjected to simple shear. Specimens with fibers oriented at −45° with respect to the applied shear load were tested. The shear and normal stress components as well as the amount of shear were simultaneously measured. Due to the initial orientation, fibers were subjected to compressive loads, resulting in buckling. The positive Poynting effect was observed when soft materials were sheared. The off-axis stiffness theory and the Murphy model at small deformations were used to predict the mechanical behavior of the soft composites. In general, there is a reasonable correlation between model predictions and measured data by adjusting only one empirical parameter. However, the model based on the off-axis stiffness shows better prediction than the Murphy model for relatively higher fiber volume fractions. From universal relations for simple shear, the results indicate that the studied composites are of a coaxial type in a weak sense.

Experimental study on the practical mitigation of passive intermodulation for time and temperature in cavity duplexer

Practical methods to mitigate level and variation of passive intermodulation with respect to time and temperature of coaxial cavity type duplexer are proposed through a variety of experimental results. From the findings derived in this study, a stable passive intermodulation response with less than 1 dB variation was shown in the environment temperature range of −10–85 °C. The duplexer with time-stable PIM response at room temperature had a stable PIM value even in the environment temperature range.

Real-time method for fabricating 3D diffractive optical elements on curved surfaces using direct laser lithography

To simplify complex optical systems, a next-generation optical component which combines a refractive element and a diffractive element is desirable. To fabricate these next-generation optical components, it is desirable to keep the focal point of the lithographic lens focused on the curved surface. Keeping the focus constant is challenging for a laser process, as well as for measuring and metrology systems. In this study, a coaxial confocal microscopic type commercialized displacement sensor was used to make it easier to fabricate the pattern required for diffractive optical elements (DOEs) on a curved surface, using direct laser lithography. The test results confirmed that a constant line width of 5 μm could be fabricated on a curved surface such as a cylinder and convex lens using the proposed auto-surface tracking system, with a position error of 1 μm. The diffraction pattern fabricated on the curved surface was analyzed for optical performance and compared with mathematical modeling.