Tube Parameters Research Articles

Radiation Dose during Digital Subtraction Angiography of the Brain-The Influence of Examination Parameters and Patient Factors on the Dose.

Cerebral vascular angiography, or digital subtraction angiography (DSA), is essential for diagnosing neurological conditions but poses radiation risks. This study aims to analyze the impact of examination parameters and patient characteristics on the radiation dose received during DSA to optimize safety and minimize exposure. A retrospective analysis of 251 DSA procedures using the GE Innova IGS 630 dual-plane instrument was conducted. Data on dose area product (DAP) and air kerma (KERMA), along with patient and examination details, were collected. Statistical analyses, including Mann-Whitney, Kruskal-Wallis, and Spearman rank correlation tests, assessed the relationships between variables and radiation dose outcomes. Significant correlations were found between the sides examined (left, right, or both) and DAP (p < 0.0001) and KERMA (p < 0.0001) values, with bilateral studies showing the highest values. The post hoc Dunn tests showed that the 'L + P' group significantly differs from both the right group (p < 0.0001 and the left group (p < 0.0001). There is no significant difference between the 'P' group and the 'L' group (p-value = 0.53). These results suggest that the right and left (both) group have unique KERMA mGy values compared to the other two groups. A strong correlation (rS = 0.87) existed between DAP and KERMA. The number of projections significantly impacted radiation dose (rS = 0.61). Tube parameters (kV and mA) and skull size had low correlations with DAP and KERMA. Optimizing imaging protocols and individualizing parameters can significantly enhance patient safety and diagnostic efficacy while also reducing occupational exposure for medical staff.

Ge quantum well channel P-MOSFET for 2.45 GHz wireless weak energy harvesting

Wireless energy harvesting is an important application of microwave wireless energy transmission system, but due to the weak energy of RF signals in the 2.45 GHz band, its rectification efficiency is not ideal. As one of the core rectifier components of wireless weak energy harvesting system, the performance of MOSFET determines the rectification efficiency of the system, and its optimized design to improve the rectification efficiency is an important direction of current research in the field. In view of this, this paper proposes and designs Ge quantum well channel PMOS for wireless weak energy harvesting at 2.45 GHz, aiming to improve the rectification efficiency of wireless weak energy harvesting systems. Starting from adjusting the structural physical parameters of the MOS tubes, the absolute value of the threshold voltage is reduced in the weak energy density region, which in turn improves the rectification efficiency of the device. Then, the novel diode connection with the introduction of substrate bias effect is compared with the conventional connection using an ADS simulation circuit, and the simulation results show that the leakage current is smaller and the rectification efficiency is higher under the novel connection. On this basis, a Ge quantum well channel PMOS device is proposed. Compared with the Ge surface channel, the hole mobility of the quantum well channel will be greatly improved, and its rectification efficiency can also be improved. The device is connected to the rectifier circuit with a novel connection and simulated using Silvaco's Mixedmode module. The results show that the rectification efficiencies of the Ge quantum well channel MOS reach 13.53 % and 32 % at low input powers of −20.34 dBm and −6.28 dBm, respectively, which are 3.3 and 1.14 times higher than those of the conventional surface channel MOS.

Cross-section extraction and model reconstruction of lava tube based on L1-medial skeleton

Lunar lava tube caves, due to their unique geographical structure and potential as shelters, have repeatedly emerged as prime candidates or priority areas during discussions on lunar base site selection. However, owing to current technological limitations and the complexities of lunar exploration, obtaining detailed data directly from the interiors of lunar lava tubes poses a significant challenge. Hence, the study of terrestrial lava tubes assumes critical importance. By delving into Earth’s lava tubes, we can gain insights into crucial aspects such as their formation mechanisms, geological characteristics, and stability, which can then inform and guide research on lava tubes found on extraterrestrial bodies like the Moon and Mars. During the data acquisition process for lava tubes, given their intricate spatial configurations and dim lighting conditions, we have opted to employ LiDAR technology to collect point cloud data, revealing the internal structural information of the lava tubes. Consequently, this paper thoroughly explores a method for extracting lava tube parameters and constructing models using this point cloud data. This approach encompasses four key steps: data preprocessing, axis construction of the lava tube, cross-sectional feature extraction, and 3D model reconstruction. Initially, raw data is refined through the creation of point cloud voxels to mitigate noise interference. Subsequently, an iterative algorithm is utilized to obtain the L1-medial skeleton, enabling precise capture of the lava tube’s axis information. Using this extracted axis, we proceed with sampling at fixed intervals to derive cross-sectional points of the lava tube. These points are then utilized to extract fundamental geometric parameters such as cross-sectional area, length, and width. Ultimately, by integrating all these cross-sectional point cloud data, a comprehensive 3D model of the lava tube is constructed. Remarkably, this method achieves a high degree of accuracy, with 99 % of the extracted cross-sectional points exhibiting an error of less than 0.12 m, and 99 % of the model’s positional errors falling within 0.15 m. This not only enhances the precision of parameter extraction but also provides significant technical support for in-depth studies of extraterrestrial volcanic activities and lava tube formation mechanisms. Furthermore, it offers a valuable tool for parameter extraction and research on other irregular natural tunnels.

Enhancing the aerodynamic performance of large-span roof using a ‘breathable’ optimization tube: A parametric study

In wind engineering community, large-span roofs are widely acknowledged to be wind-sensitive, and oftentimes aerodynamic optimization is needed to enhance its wind-resistance. For such purpose, we proposed a “breathable” aerodynamic optimization tube in this study, the performance of which was experimentally examined via a series of wind tunnel tests. The results showed that, the proposed aerodynamic optimization tube is capable to significantly reducing the wind loads on the large-span roof, the effectiveness of which varies with different tube parameters. On this account, the effect of six key parameters, namely section shape, inlet-outlet angle, hole size, in-out ratio, hole distance and inlet hole length were examined independently. Overall, the outcomes are expected to provide important implications regarding the wind-resistance design of large-span roof structures.

Systematic approach to measure the performance of microchannel-plate photomultipliers

In this paper, we present our approach to systematically measure numerous performance parameters of microchannel plate photomultiplier tubes. The experimental setups, the analyses and selected results are discussed. Although the techniques used may be different in other locations, the document is intended as a guide for comparable measurements with other types of microchannel plate photomultiplier tubes. Measurements are shown for the following performance parameters: spectral and spatial quantum efficiency, collection efficiency, gain as a function of voltage, position and magnetic field, time resolution, rate capability and lifetime. By using a dedicated 3-axis stepper and an FPGA-based data acquisition system, also inner PMT parameters are measured as a function of the active area, such as relative detection efficiency, dark count rate, time resolution, recoil electron and afterpulse distributions, as well as charge sharing and electronic crosstalk. In addition, some of the parameters are investigated inside a strong magnetic field. For many of these measurements, the change of most setup parameters and the subsequent analysis can be controlled semi-automatically by software scripts.

Evaluation of eustachian tube and mastoid parameters in chronic otitis media: A computed tomography-based study

Objectives: The study aimed to understand the causes of chronic otitis media (COM) with unilateral or bilateral cholesteatoma by examining the eustachian tube (ET) and mastoid ventilation from preoperative high-resolution temporal computed tomography (HRTCT) scans. Patients and Methods: In this retrospective case-control study, COM patients with cholesteatoma who underwent preoperative HRTCT scanning between January 2021 and December 2023 were analyzed. The study included 102 ears of 51 participants (31 males, 20 females; mean age: 35.7±14.0 years; range, 18 to 65 years). The participants were divided into three groups, each with 17 individuals: unilateral COM with cholesteatoma, bilateral COM with cholesteatoma, and a healthy control group. Variables, including Reid plane-ET angle, tubotympanic angle (TTA), ET length, ET tympanic orifice and isthmus widths, and mastoid ventilation type and volume, were examined in CT images. Results: The mean left TTA (p=0.045) was higher in the unilateral cholesteatoma group compared to the control group (148.88±5.30 and 144.24±6.51, respectively; p=0.045). The bilateral cholesteatoma group exhibited higher values for right and left ET isthmus widths (p=0.015 and p=0.014, respectively). The control group had significantly higher mastoid volumes compared to groups with cholesteatoma (p&lt;0.001). Type 3 mastoid distribution was notably higher in groups with cholesteatoma (p&lt;0.001). In the control group, the mean right and left ET angles were 25.13±3.35° and 24.67±3.38°, respectively. Conclusion: Tubotympanic angle and ET isthmus width may be a potential marker for cholesteatoma. Large-scale studies targeting the anatomy and function of the isthmus in combination with mastoid and ET radiomorphological data and clinical scores using standardized protocols may improve treatment strategies.

Forced convective rate and pressure drop through a packed annulus: a numerical simulation

Porous materials are used in engineering and industry due to their heat transmission qualities. This study examined forced convection flow through an annular tube packed with sphere balls of various materials and sizes using numerical analysis. The sphere balls were permeable. Ceramic, plastic, and steel with spherical diameters of 3, 5, and 6 and porosity of 0.4 were tested for heat dissipated and fluid flow. Also, test the impact of steel balls of diameter 6mm with 0.6 and 0.8 porosity. The numerical simulation results are used to analyze the forced convection and fluid flow parameters of a three-dimensional annular tube with continuous heat flux in the Reynold number range (5000-14000). Steel balls had an 80% higher heat transfer coefficient than annular tubes without porous mediums. The simulation showed that inserting the porous media increased annular tube pressure loss. The maximum heat transfer coefficient improved by about 80% when the spherical diameter is 3 mm. Also, the result illustrated the heat transfer coefficient of steel balls Increased by about 79%, 69%, and 49%, with 0.4, 0.6, and 0.8 respectively

Analysis and Modeling Study on the Effect of Working Parameters of Portable Neutron Tubes on Target Current

Abstract As an important parameter index of sealed neutron tubes, their high-pressure side target current directly affects neutron yield. The working parameters of a neutron tube affect the target current. Using self-developed neutron tubes, the influence of operating parameters of neutron tubes on target current was studied. The effect curves of gas pressure, anode high pressure, and target high pressure on neutron yield were obtained, and the secondary electron suppression characteristics of the target current were obtained. Further, we analyze and fit a multi-parameter coupling model for the target current, to provide a theoretical basis for establishing the working state and improving the performance of sealed neutron tubes.

Digital Subtraction Angiography of Cerebral Arteries: Influence of Cranial Dimensions on X-ray Tube Performance.

(1) Background. Digital subtraction angiography (DSA) is indispensable for diagnosing cerebral aneurysms due to its superior imaging precision. However, optimizing X-ray parameters is crucial for accurate diagnosis, with X-ray tube settings significantly influencing image quality. Understanding the relationship between skull dimensions and X-ray parameters is pivotal for tailoring imaging protocols to individual patients. (2) Methods. A retrospective analysis of DSA data from a single center was conducted, involving 251 patients. Cephalometric measurements and statistical analyses were performed to assess correlations between skull dimensions and X-ray tube parameters (voltage and current). (3) Results. The study revealed significant correlations between skull dimensions and X-ray tube parameters, highlighting the importance of considering individual anatomical variations. Gender-based differences in X-ray parameters were observed, emphasizing the need for personalized imaging protocols. (4) Conclusions. Personalized approaches to DSA imaging, integrating individual anatomical variations and gender-specific differences, are essential for optimizing diagnostic outcomes. While this study provides valuable insights, further research across multiple centers and diverse imaging equipment is warranted to validate these findings.

Research on the prediction model of energy separation effect of vortex tube based on trajectory deflection characteristics and its numerical solution method

In this paper, in order to establish the energy separation mechanism of the vortex tube, the hydrodynamic behavior of the compressible fluid in the asymmetric cavity space is investigated, and a numerical model of the trajectory deflection behavior is deduced and established; in order to form the optimal design method of the structural parameters of the vortex tube, the force situation of the fluid microelements entering different regions of the vortex chamber of the vortex tube is analyzed, and the trajectory deflection equations are corrected by combining with the expansion behavior of the fluid and the characterizing equations of vortex strength, transportability, and vortex initiation characteristics are given. The characterization equations of vortex strength, transportability and vortex initiation characteristics are given, and the numerical simulation of their influence parameters is carried out; in order to realize the prediction of the vortex tube performance of a given structure, the multifactor Pearson thermodynamic map is used to correlate and analyze the experimental data of vortex tubes reported publicly in the past years, and the polynomial regression equations are designed and established for the prediction of the vortex tube's energy separation effect and the confidence level and the degree of coincidence of the prediction results are examined. The confidence level and degree of agreement of the prediction results were examined. It is found that: the trajectory deflection motion of the compressible fluid in the asymmetric cavity space is the result of the combined effect of structural air pressure bias and the expansion behavior of the incident fluid; in order to improve the vortex strength in the vortex tube, the vortex initiation chamber space should be as small as possible; the increase of the diameters of the hot-end pipe and the cold-end pipe is conducive to the enhancement of vortex strength, but at the same time, it weakens the vortex transport in the heat pipe; the vortex initiation chamber size has a negative correlation with the hot-end temperature rise, and the inlet fluid pressure has a The negative correlation between the size of the vortex chamber and the temperature rise at the hot end, the positive correlation between the increase of inlet fluid pressure and the resulting temperature rise, and the strong correlation between the inlet fluid pressure and the friction coefficient on the effect of energy separation; the predictive equations for the effect of energy separation obtained by the fitting are in good agreement with the real situation.

Structural Design of Pressurized Tube Based on the Discrete Element Method–Computational Fluid Dynamics Coupled Simulation

In order to elucidate the impact of pressurized tubes’ structures on the sowing performance of pneumatic seed delivery systems, the EDEM–CFD coupled simulation method was employed to analyze the influence of pressurized tube parameters, including length (L), corrugation depth (S), corrugation width (K), and the number of corrugations, on seed movement characteristics, distribution uniformity, and airflow patterns. Simulation-validated experiments were conducted to study the impact of the optimal pressurized tube structure on seeding performance. The results indicate that pressurized tubes significantly enhance the uniformity coefficient of seed distribution, reduce seed velocity, and decrease the coefficient of variation in distribution uniformity. When pressurized tube parameters, specifically length (L), corrugation depth (S), corrugation width (K), and the number of corrugations, are set at 800 mm, 8 mm, 50 mm, and 6, respectively, the uniformity coefficient of seed distribution exceeds 95%, and the coefficient of variation in seed discharge consistency for each row is less than 3.2%. Moreover, the seed velocity at the outlet of the pressurized tube, the relative velocity of two-phase flow, and pressure loss are all minimal, indicating superior seeding performance. This research provides valuable insights into the analysis of seed movement characteristics within pressurized tubes and the optimization of their structural parameters.

A novel acquisition strategy of process parameters for spatial tubes with variable curvature formed by free bending technology

A novel acquisition strategy of process parameters for spatial tubes with variable curvature formed by free bending technology

Numerical simulation of flow distribution characteristics in carbon dioxide microchannel evaporator

Microchannel heat exchangers find widespread use in household and automotive air conditioning due to their compact structure and high efficiency. However, two-phase refrigerant flow mal-distribution in microchannels limits their application. For the CO2 heat pump, the performance reduction by flow mal-distribution could be as large as 20%. This study proposed an approach to mitigate flow mal-distribution by inserting a perforated tube into the header of a microchannel evaporator in CO2 heat pump. Numerical simulations were carried out to investigate the impact of perforated tube parameters and CO2 inlet conditions on flow distribution. Results show a 24.4% increase in total non-uniformity (S) of flow distribution with a perforated tube. A higher number of openings and smaller diameters enhance uniformity, with the 10-hole, 2 mm diameter perforated tube proving most effective. Additionally, the most uniform flow distribution was achieved at an inlet CO2 mass flow rate of 30 g/s and a vapor quality of 0.2. And the flat tubes with an insertion depth of 5 mm and a cross-section of 16 × 2 mm is the most beneficial for uniform flow distribution.

Simultaneous detection of melamine and cyanuric acid using powder X‐ray diffraction

AbstractA novel, non‐destructive, powder X‐ray diffraction (P‐XRD) approach was developed and validated for the simultaneous detection of melamine (ME) and cyanuric acid (CA). Sample holders, and a range of P‐XRD X‐ray tube parameters (voltage: 25–45 kV; current: 25–45 mA), and scanning conditions (scan step size: 0.006–0.10°; step time: 50–150 s) were experimented at 2θ conditions. Based on the obtained diffraction patterns, the following conditions were optimized: sample holder: reflection‐transmission spinner, tube voltage: 45 kV, tube current: 45 mA, scan step size: 0.006°, and scan step time: 150 s. The crystalline properties were assessed and phase quantification of both ME and CA was performed using Rietveld refinement, aligning to the International Center for Diffraction Data (ICDD) PDF4+ 2023 library. The approach was validated considering repeatability, precision, and linearity, and recovery and stability studies also support the findings. The limit of detection (LOD) was found to be 0.2 to 1 wt. % per phase of powder sample. Then, spiked and real food powder samples were screened for ME and CA. To date, there is no nondestructive technique available to simultaneously detect ME and CA in a single run. The developed P‐XRD approach can find vast applications in quality testing facilities.

Novel entropy generation and optimization for hybrid nanofluid flow via ribbed surface parabolic trough collector

This research paper focuses on the optimization of parameters for deformative receiver tubes to achieve prime choice of design for efficient energy absorption. The motivation of the current study lies in addressing the critical need for optimizing parameters of deformative receiver tube to obtain optimal design to enhance energy absorption efficiency in Parabolic Trough Solar Collectors (PTSC). Considering the diverse criteria involved in the design process, the application of a Multi Criteria Decision Making (MCDM) approach proves beneficial. The primary objective of this study is to identify the optimal combination of parameters (Reynolds number (Re), Relative V-rib height (Rh/ Dt), Relative streamwise pitch (PStm/Rh), and Relative spanwise pitch ratio (PSpn/Rh)) of the deformative receiver tube of PTSC) employing the multiobjective optimization based on ratio analysis (MULTIMOORA) method. Additionally, a novel Pythagorean fuzzy sets (PFSs) entropy-based approach is proposed for quantifying the weights of the criteria. The feasibility and practicality of the novel PFSs entropy and MULTIMOORA method are demonstrated through the application of the Technique for Order of Preference by Similarity to Ideal Solution method (TOPSIS), confirming the attainment of Re = 50000, Rh/ Dt=0.0135, Pstm/ Rh=56.67 and Pspn/ Rh=11.11, as optimal alternative parameters. This research offers valuable insights into optimizing deformative receiver tube parameters to improve thermal performance which benefiting researchers in the concerned field.

Numerical analysis and design methods of grout-filled GFRP tube repaired corroded CHS T-joints

This study explores the compressive behavior of Grout-Filled GFRP Tube (GFGT) repaired corroded circular hollow section (CHS) T-joints. Finite element models of GFGT repaired corroded joints were developed, validated, and utilized to examine the influence of the joint geometric, material, and chord end stress parameters on the compressive strength and repairing efficiency of the joints. The findings reveal that the ultimate strength of the GFGT repaired joint increases with a thicker GFRP tube, a lower repaired chord section hollow ratio, a higher grout strength, and a longer repaired range. By optimizing the repairing parameters of the grout-filled GFRP tube, the compressive strength of GFGT repaired corroded joints with 16% and 32% corrosion rates can be up to increase to 164% and 147% of the uncorroded counterparts, respectively. The chord end stress exerts a similar but weaker effect on the repaired joints than on the unrepaired joints. A series of suggestions were proposed for repairing joints with different corrosion degrees to achieve a 20% ultimate strength enhancement compared to uncorroded joints. The compressive strength degradation rate of corroded joints was accurately predicted by the design method in the CIDECT and prEN guidelines. The feasibility of the guideline formulae to evaluate the strength reduction rate caused by the chord end preload was verified. A design method to predict the compressive strength of GFGT repaired corroded joints was proposed.

Crushing characteristics and multi-objective optimisation of a novel bionic frog leg tube

Recently, the demands for structural impact protection in automobile, train, aerospace and other fields have become increasingly intense, and the bionic energy absorption structures have attracted widespread attention for their excellent structural properties and crushing characteristics. In this study, inspired by the great impact resistance of the frog legs, a novel bionic frog leg tube was proposed and investigated by numerical simulation and parametric study. Firstly, according to the structural forms of the legs for frogs, humans and pigs, three types of bionic leg tubes were designed, and the energy absorption characteristics of these tubes subjected to axial loading were investigated, it was found that the peaking crushing force ( PCF ) and undulation of load-carrying capacity ( ULC ) seem to have a strong relationship with the jumping ability for animals, lower PCF and ULC could decrease the injury transmitted to the body. Then, the parametric studies were conducted to investigate the effects of structural parameters on the crushing behaviour of the bionic tubes, the results indicated that a bionic frog leg tube with smaller L 1 tends to present the concertina deformation mode, and a larger L 1 will lead to the diamond mode or mixed mode. Lastly, the multi-objective optimisation of the bionic frog leg tube was carried out to simultaneously improve specific energy absorption ( SEA ), crushing force efficiency ( CFE ), and reduce ULC , based on the NSGA-II algorithm. The optimal configuration of the structural parameters of the bionic tube was obtained, and the bionic tubes present better crashworthiness characteristics than initial structures under the axial loading. The findings of this study provide new insights into the transformation of natural biological inspiration into engineering applications for protective structures.

Experimental analysis and numerical simulation of ignition delay time of diesel fuel using a shock tube

The present work consisted in developing a computational routine for prediction and characterization ignition delay time, pressure, temperature generated and energy released in the combustion process in a shock tube. Mathematical modeling considered the high-pressure region of the shock tube known as the conducted section. The Lazarus code compiler was used to generate the unstructured triangular meshes and to implement the computational routines to simulate the propagation of shock waves inside the shock tube. The mathematical modeling used the geometric parameters of the shock tube of the combustion laboratory of the Federal University of Minas Gerais and was based only on the displacement of the shock wave after the diaphragm rupture. The main objective of the work was the development of computational routines to characterize the shock wave parameters of the ignition delay times of conventional diesel to validate the experimental tests carried out in the shock tube conducted by Santana et al. [3] and compare it with the experimental tests and numerical simulations carried out by other authors available in the literature. A linear regression of the experimental tests conducted by Santana et al. [3] with conventional diesel was performed to obtain the Arrhenius equation for numerical simulation of the ignition delay time of diesel under the following conditions: temperatures from 880 to 1300 K, pressures 24 bar and equivalence ratio 1. The results show good prediction between experimental tests and numerical simulations. Were found delay times ranging from 425 to 1890 μs. Considering all temperature range, the difference between the experimental and simulated test was approximately 15%, this difference also can be explained by the measurement in the shock tube, that the ignition delay time was calculated by the time difference between the passage of the shock wave by the pressure sensor and the start of the ignition detected by the luminosity detection sensor. This work is relevant because it was developed computational routine in open software and the results achieved in the simulation were considered satisfactory, since they are in the same order of magnitude as the results found in the experimental tests carried out by Santana et al. [3] and other works.

Effect of Welding Process on Energy Absorption Parameters of a Square Tube with Emphasis on the Number and Position of Welding Lines

Effect of Welding Process on Energy Absorption Parameters of a Square Tube with Emphasis on the Number and Position of Welding Lines

The influence of tube diameter parameters on the flow resistance and heat transfer characteristics of supercritical CO2 in horizontal tubes

The diameter parameters of tubes are crucial for the flow and heat transfer characteristics of supercritical fluids. however, the diameter effect has not been fully understood. The existing literatures only investigate the effect of different tube diameters on the flow and heat transfer characteristics within a narrow parameter range, lacking specific theoretical analyses and verification in a wide range of parameters. Therefore, experimental research was conducted to investigate the influence of tube diameter parameters on the flow resistance and heat transfer of supercritical carbon dioxide(sCO2) in horizontal tubes and an explanation of the tube diameter effect mechanism is provided based on pseudo-boiling theory. Stainless steel smooth circular tubes with diameters of 8 mm, 10 mm, and 12 mm were used as the test section, and various experiments were carried out under the range of mass flux (G): 509.23–1267.34 kg/m2s, heat flux (qw): 97.91–410.43 kW/m2, and operating pressure (P): 5.54–20.32 MPa. From the pseudo-boiling theory analysis, the influence of tube diameter parameters has a greater influence on the heat transfer in the two-phase-like (TPL) regime and is almost negligible when the P exceeded 1.5Pc, indicating the interaction between liquid-like (LL) and vapor-like (VL) phases is found to be the dominant reason for the tube diameter effect on heat transfer and the correlations for predicting the maximum wall temperature difference between the top and bottom generatrix (ΔTmax) are established. The present work can significantly enhance the understanding on sCO2 flow boiling mechanism and provide a new research direction for supercritical fluid.