Cone Diameter Research Articles

Optimization and experimental validation of a high-efficiency oil–water cyclone separator for well testing conditions

The performance of surface oil–water cyclone separators impacts the measurement accuracy of crude oil produced from exploration and appraisal wells, thereby influencing the formulation of exploration and development plans. To obtain the optimal structural configuration for cyclone oil–water separators, this study optimizes the design of a high-efficiency oil–water cyclone separator suitable for special conditions in well testing. A numerical simulation was performed using the discrete phase model to analyze the three-dimensional turbulent swirl field of the oil–water phases within the separator. Separation efficiency and pressure drop were used as evaluation criteria. The Plackett–Burman experimental method was employed to evaluate six factors affecting separation performance, with oil outlet diameter and cyclone chamber cone angle identified as significant factors. Mathematical models for separation efficiency and pressure drop were developed based on these factors. The central composite design method was then applied to investigate the interactive effects of oil outlet diameter and cyclone chamber cone angle on separation efficiency and pressure drop. The optimal parameter combination was determined: oil outlet diameter of 4.241 mm and cyclone chamber cone angle of 9.622°. The predicted separation efficiency was 93.870%, and the predicted pressure drop was 48.287 kPa. Field tests of the optimized cyclone separator verified the rationality of these optimized parameters, achieving a separation efficiency of 92.9%. This research offers a foundation for optimizing the design of oil–water cyclone separators.

Two Omnidirectional Antenna Models for Ship Hull Corrosion Detection Radar System

This paper discusses two modified monopole antenna models. These antenna models are designed to detect hull corrosion of ships, which is predicted to be the cause of hull leaks. The modification was carried out by adding a conical parasitic element aimed at widening the bandwidth and increasing the antenna gain. The conical parasitic on the first antenna is directed upwards, while the second is the opposite. The first model uses a cone with a larger diameter than the second model. The calculation of the cone diameter is based on half the wavelength of the frequencies generated by the antenna. With a smaller diameter, PTFE is added between the monopole and the parasitic cone to avoid short circuits. This configuration is intended to see the effective antenna model widen the bandwidth and increase the gain. Antenna performance testing was carried out using a vector network analyzer and software-defined radio. The test results show that both antenna models are omnidirectional in radiation. The first model operates at a frequency of 3904.7 - 7793.1 MHz with a bandwidth of 3888.4 MHz and a highest gain of 10 dBi. The second model operates at a frequency of 2282.4 - 3324.1 MHz with a bandwidth of 1041.7 MHz and a highest gain of 8dBi. Thus, the first antenna model has a higher bandwidth and gain than the first model, but both have met the requirements for ship hull corrosion detection antennas.

DEM simulation of cone penetration tests in sand in a virtual calibration chamber

In this paper, cone penetration tests (CPT) in a virtual calibration chamber (VCC) were simulated using the discrete element method (DEM) to investigate the factors influencing the cone penetration tip resistance (qc) in sand. The microscopic parameters of the Fontainebleau sand were calibrated by comparing the simulated macroscopic mechanical behavior to that from experimental drained triaxial tests. The influences of VCC dimensions and prescribed boundary conditions, penetration rate, and confining stress on the qc were investigated. The results show that the qc under different boundary conditions converges as the diameter of the VCC increases. It is recommended that a ratio of chamber diameter to cone diameter larger than 20 should be used to eliminate the potential boundary effects for CPT in VCC for samples of different relative density (Dr). The comparison between the numerical simulations and cavity expansion theory predictions presents significant relationships among critical state parameters (Ψcri), peak internal friction angle (φpeak) and normalized cone tip resistance (Q).

Spray characteristics and combustion mechanism influence on combustion stability of UDMH/NTO pre-combustor under external excitation

To study the combustion stability of liquid rocket engines with hypergolic propellant more comprehensively, external pressure pulse excitation was applied to the UDMH (unsymmetrical dimethylhydrazine)/NTO (methylhydrazine) pre-combustor. The effects of pressure pulse intensity, spray characteristics (droplet diameter and spray cone angle), and combustion mechanism on combustion stability characteristic frequencies and attenuation characteristics after excitation were investigated. The simulation results show that all operation conditions capture the first three longitudinal frequencies of the pre-combustor, and all factors have a greater impact on frequencies with higher orders. Increasing the pulse intensity and reducing the droplet diameter are not conducive to combustion stability. The influence of the spray cone angle on the combustion stability is not monotonous. The pre-combustor has good stability when the spray cone angle is 70°. Different combustion mechanisms have a significant effect on the results before and after pressure pulses, and considering a more complete combustion process may increase the attenuation time in the pre-combustor. The obtained rules can provide a reference for the design and simulation of hypergolic liquid rocket engines, which is beneficial for predicting and evaluating the combustion stability of liquid rocket engines.

Standardization of Variable Taper Files and Corresponding Gutta-Percha Cones Amongst Manufacturers

IntroductionCurrently there is no standardization of variable taper endodontic files and corresponding gutta-percha (GP) cones. The aim of this study was to evaluate intramanufacturer and intermanufacturer variability of diameter and taper in the apical third of GP master cones and finishing files from 3 commercially available variable taper endodontic systems. MethodsDiameter measurements were recorded using digital microscopy at 1-mm increments (D1-D4) for F2 files and corresponding GP cones (n = 20 per system) from ProTaper Gold (Dentsply Tulsa Dental Specialties, Johnson City, TN), EdgeTaper Platinum (EdgeEndo, Albuquerque, NM), and ExactTaper H (SS White, Lakewood, NJ). Taper was defined as the rate of change in diameter per 1-mm increment. Mean differences in diameter were assessed using repeated measures of analysis of variance for D1 to D4 and the Wilks test for differences in taper. ResultsIn the apical third, ProTaper and EdgeEndo mean file diameters were significantly smaller than corresponding GP cone diameters (P < .01, P < .01, respectively). Contrastingly, SS White file diameters were significantly larger than their corresponding GP cones (P = .02). Files from all manufacturers had significantly smaller diameters than advertised (nominal) values (P < .01). ProTaper GP cones had similar diameters to nominal values (P = .30), while EdgeEndo and SS White GP cones were significantly smaller (P < .01). Amongst files and corresponding GP cones from all systems, taper was nonstandardized. ConclusionsSize discrepancies between finishing files and corresponding GP cones can be expected amongst variable taper endodontic systems. Therefore, clinicians should be prepared to make intraoperative adjustments when obturating.

Comparative Analysis of Armature Structure on Constant Force Characteristics in Long-Stroke Moving-Iron Proportional Solenoid Actuator

The influence of key design parameters on the constant force characteristics of long-stroke moving-iron proportional solenoid actuators (MPSAs) has been explored by a method combining finite element modelling and correlation analysis. First, the finite element model (FEM) of long-stroke MPSA was developed and validated. Subsequently, the two evaluation indexes, the average-output solenoid force and maximum-output solenoid force variability, were introduced to disclose the influence law of pole shoe parameters on the constant force characteristics of a long-stroke MPSA. After that, correlation analysis was employed to quantify the influence of several parameters and parameter interaction factors on the constant force characteristics. The results indicate a strong contradiction between the average-output solenoid force and maximum-output solenoid force variability; however, increasing the inner diameter of the cone helps enhance the average-output solenoid force without causing maximum-output solenoid force variability to increase. Among all the parameters examined, the cone angle is the most significant parameter affecting the constant force characteristics. Additionally, interactions between the cone angle and the cone length, the cone angle and the inner cone diameter, the cone angle and the outer cone diameter, the cone length and the outer cone diameter, as well as the inner cone diameter and the outer cone diameter also have an important influence on the constant force characteristics. This study deepens our understanding of how the key parameters affect the constant force characteristics and assists designers in optimizing these parameters for developing new structures.

Analysis on the relationship between Schneiderian membrane thickening in the posterior maxillary region and periapical lesions by cone beam computed tomography.

This study aimed to evaluate the thickening of sinus membrane, which is also named Schneiderian membrane (SM), in patients and its relationship with periapical lesions (PAL) in the posterior maxillary region to provide reference for the prevention and treatment of odontogenic maxillary sinusitis. A retrospective analysis was conducted on 554 cone beam computed tomography (CBCT) imaging data of maxillary sinuses from 301 patients who met the inclusion criteria to determine the correlation between PAL and SM thickening in the posterior maxillary region. Cases of pathological SM were recorded and classified on the basis of the degree and type of SM thickening. The correlation between SM thickening and the diameter of PAL, the relationship between the upper edge of PAL and the maxillary sinus floor, and its relationship with whether affected teeth with PAL undergo root canal treatment were evaluated. The detection rate of SM thickening in patients with PAL was significantly higher than in those without PAL, so PAL was correlated with SM thickening. Analysis on the correlation between PAL detection indicators and SM thickening degree showed that SM thickening degree was positively correlated with PAL diameter (cone beam computed tomography-periapical index) and not correlated with the three spread effects between the upper edge of PAL and the maxillary sinus floor, as well as whether the teeth with PAL undergo root canal treatment. The correlation analysis between PAL detection indicators and SM thickening types showed that whether the teeth with PAL undergo root canal treatment was not correlated with SM thickening types, and the diameter of PAL, the three spread effects between the upper edge of PAL, and the maxillary sinus floor were not correlated with SM thickening types. The PAL of posterior maxillary teeth is closely related to SM thickening, and the diameter of PAL is positively correlated with the degree of SM thickening. Patients with PAL who have undergone root canal treatment often exhibit SM polyp thickening. In addition, the relationship between the upper edge of PAL and the maxillary sinus floor does not affect the possibility of SM development.

Microstructure-based modelling of snow mechanics: experimental evaluation of the cone penetration test

Abstract. Snow is a complex porous material presenting a variety of microstructural patterns. This microstructure largely controls the mechanical properties of snow, although the relation between the micro and macro properties remains to be better understood. Recent developments based on the discrete element method (DEM) and three-dimensional microtomographic data make it possible to reproduce numerically the brittle mechanical behaviour of snow. However, these developments lack experimental evaluation so far. In this study, we evaluate a DEM numerical model by reproducing cone penetration tests on centimetric snow samples. The microstructures of different natural snow samples were captured with X-ray microtomography before and after the cone penetration test, from which the grain displacements induced by the cone could be inferred. The tests were conducted with a modified snow micropenetrometer (5 mm cone diameter), which recorded the force profile at a high resolution. In the numerical model, an elastic–brittle cohesive contact law between snow grains was used to represent the cohesive bonds. The initial positions of the grains and their contacts were directly derived from the tomographic images. The numerical model was evaluated by comparing the measured force profiles and the grain displacement fields. Overall, the model satisfactorily reproduced the force profiles in terms of mean macroscopic force (mean relative error of about 20 %) and the amplitude of force fluctuations (mean relative error of about 55 %), while the correlation length of force fluctuations was more difficult to reproduce (mean relative error of about 40 % for two samples out of four and by a factor ≥ 8 for the other two). These characteristics were, as expected, highly dependent on the tested sample microstructure, but they were also sensitive to the choice of the micromechanical parameters describing the contact law. A scaling law was proposed between the mechanical parameters, the initial microstructure characteristics and the mean macroscopic force obtained with the DEM numerical model. The model could also reproduce the measured deformation around the cone tip (mean grain displacement relative error of 57 % along the horizontal axis), with a smaller sensitivity to the contact law parameterisation in this case. These detailed comparisons between numerical and experimental results give confidence to the reliability of the numerical modelling strategy and opens promising prospects to improve the understanding of snow mechanical behaviour.

Numerical and experimental evaluation of the performance of agravitational vortex turbine rotor

In this study, the evaluation of the rotor performance of agravitational vortex turbine (TVG) for its application indistributed power generation is presented. A numerical analysiswas carried out on a specific configuration of a TVG,characterized by its spiral inlet and conical discharge. Thedimensions of the discharge chamber and the inlet channel, suchas the inlet channel width (w), length (L), and height (h), thedischarge cone height (H) and diameter (d), and the envelopeangle (γ) were determined through previous optimization studiesdocumented in the literature. These dimensions are related to thebasin diameter (D), which was set at 500 mm for this study. Theratios used, such as L/D, h/D, H/D, γ w/D and d/D were 1.518,0.565, 1.572, 92.41°, 0.362, and 0.108, respectively.The rotor has a curvature and a helical pitch angle of 68.8°, has 6blades, a rotor height of 200 mm and the middle section of therotor is 314.4 mm (0.4H) from the top of the discharge cone, withan lower and upper diameter of151.60 mm and 284.44 mm. Usinga three-dimensional computational domain and unsteady flowsimulations, efficiency curves as a function of angular velocitywere obtained. In addition, the TVG was manufactured andexperimental tests were carried out on a laboratory-scale testbench to validate its performance. These tests allowed us tocompare the experimental results (33.84% at 88 RPM) with thenumerical results (32.67% at 106,667 RPM), revealing adifference of 3.37% between the maximum efficiency values. Itis essential to continue the turbine optimization process to ensurethat the designed TVG plays a role in fostering sustainability andfacilitating the shift towards cleaner and sustainable energyalternatives.

Comparative analysis and enhancement of conical component calculation under internal pressure in European pressure vessel Standards

This paper presents a comprehensive analysis of conical components in pressure vessels emphasizing their significance when utilized to transition between different diameters or slopes. A thorough design and analysis are underscored as essential for ensuring the safety and reliability of these components under diverse loading circumstances. The paper aims to propose enhancements to the European Pressure Vessel Standards concerning conical components under internal pressure, with a focus on improving safety, reliability, and compliance with industry standards. Existing European standards are reviewed, identifying potential gaps and proposing practical solutions. The paper also presents research findings on the influence of cone apex angles, shell geometries and design pressure on cone plate thickness calculations. A new methodology for the design and analysis of conical components in pressure vessels is proposed, offering a potential pathway to safer and more efficient pressure vessels. A range of cylinder diameter between 1000 and 2500 mm and cone angles between 30° and 60° are used as input to quantify the difference in cone thickness for a design pressure ranging between 10 and 200 barg. The proposed method yields results much closer to AD2000 compared to EN13445, leading to slightly thicker cones (up to 2.2 mm for the selected range of cone diameters and angles) compared to the former, resulting in safer pressure vessel design, and thinner cones (up to 22 mm) compared to the latter resulting in significant material savings. A comparative analysis was performed through Finite Element Analysis validating the EN13445 unsuitability for cone thickness calculations. A modification is proposed for equation (7.6)-(8) in EN13445 resulting in thinner plates reducing the cone plate thickness difference to 0.9 % on average compared to the current deviation of -9.6 % on average for the selected range of cylinder diameters and cone angles.

Minibeam Radiation Therapy Treatment (MBRT): Commissioning and First Clinical Implementation

Minibeam radiation therapy (MBRT) is characterized by the delivery of submillimeter-wide regions of high "peak" and low "valley" doses throughout a tumor. Preclinical studies have long shown the promise of this technique, and we report here the first clinical implementation of MBRT. A clinical orthovoltage unit was commissioned for MBRT patient treatments using 3-, 4-, 5-, 8-, and 10-cm diameter cones. The 180 kVp output was spatially separated into minibeams using a tungsten collimator with 0.5 mm wide slits spaced 1.1 mm on center. Percentage depth dose (PDD) measurements were obtained using film dosimetry and plastic water for both peak and valley doses. PDDs were measured on the central axis for offsets of 0, 0.5, and 1 cm. The peak-to-valley ratio was calculated at each depth for all cones and offsets. To mitigate the effects of patient motion on delivered dose, patient-specific 3-dimensional-printed collimator holders were created. These conformed to the unique anatomy of each patient and affixed the tungsten collimator directly to the body. Two patients were treated with MBRT; both received 2 fractions. Peak PDDs decreased gradually with depth. Valley PDDs initially increased slightly with depth, then decreased gradually beyond 2 cm. The peak-to-valley ratios were highest at the surface for smaller cone sizes and offsets. In vivo film dosimetry confirmed a distinct delineation of peak and valley doses in both patients treated with MBRT with no dose blurring. Both patients experienced prompt improvement in symptoms and tumor response. We report commissioning results, treatment processes, and the first 2 patients treated with MBRT using a clinical orthovoltage unit. While demonstrating the feasibility of this approach is a crucial first step toward wider translation, clinical trials are needed to further establish safety and efficacy.

Thermohydraulic performance augmentation of triangular duct solar air heater using semi‐conical vortex generators: Numerical and experimental study

AbstractThermohydraulic performance augmentation using turbulence promotors is a commonly adopted technique in solar air heater (SAH) applications. This article presents the thermohydraulic performance augmentation of triangular duct SAH using semi‐conical vortex generators (SCVG) using computational fluid dynamics and experimental methodology for various flow Reynolds numbers ranging from 6000 to 21,000. An in‐depth parametric analysis is undertaken to establish the influence of flow attack angle, relative longitudinal pitch, relative transverse pitch and cone diameter of SCVG on the thermohydraulic performance as indicated by the thermohydraulic performance parameter (THPP). The results reveal that the SCVG generates longitudinal vortices and introduces flow impingement zones which significantly affects the flow and heat transfer characteristics of air heaters. Correlations for Nusselt number and friction factor are established, which predicts the performance outcomes with an average error of 6.74% and 4.46%, respectively. The optimal THPP is determined to be 1.74 using artificial neural network model and Bonobo Optimization algorithm. The SCVG produces THPP values well above unity for the entire flow Reynolds number range of 6000–21,000.

Accurate machine-specific reference and small-field dosimetry for a self-shielded neuro-radiosurgical system.

The newly available ZAP-X stereotactic radiosurgical system is designed for the treatment of intracranial lesions, with several unique features that include a self-shielding, gyroscopic gantry, wheel collimation, non-orthogonal kV imaging, short source-axis distance, and low-energy megavoltage beam. Systematic characterization of its radiation as well as other properties is imperative to ensure its safe and effective clinical application. To accurately determine the radiation output of the ZAP-X with a special focus on the smaller diameter cones and an aim to provide useful recommendations on quantification of small field dosimetry. Six different types of detectors were used to measure relative output factors at field sizes ranging from 4to 25mm, including the PTW microSilicon and microdiamond diodes, Exradin W2 plastic scintillator, Exradin A16 and A1SL ionization chambers, and the alanine dosimeter. The 25mm cone served as the reference field size. Absolute dose was determined with both TG-51-based dosimetry using a calibrated PTW Semiflex ion chamber and measurements using alanine dosimeters. The average radiation output factors (maximum deviation from the average) measured with the microDiamond, microSilicon, and W2 detectors were: for the 4mm cone, 0.741 (1.0%); for the 5mm cone: 0.817 (1.0%); for the 7.5mm cone: 0.908 (1.0%); for the 10mm cone: 0.946 (0.4%); for the 12.5mm cone: 0.964 (0.2%); for the 15mm cone: 0.976 (0.1%); for the 20mm cone: 0.990 (0.1%). For field sizes larger than 10mm, the A1SL and A16 micro-chambers also yielded consistent output factors within 1.5% of those obtained using the microSilicon, microdiamond, and W2 detectors. The absolute dose measurement obtained with alanine was within 1.2%, consistent with combined uncertainties, compared to the PTW Semiflex chamber for the 25mm reference cone. For field sizes less than 10mm, the microSilicon diode, microDiamond detector, and W2 scintillator are suitable devices for accurate small field dosimetry of the ZAP-X system. For larger fields, the A1SL and A16 micro-chambers can also be used. Furthermore, alanine dosimetry can be an accurate verification of reference and absolute dose typically measured with ion chambers. Use of multiple suitable detectors and uncertainty analyses were recommended for reliable determination of small field radiation outputs.

2585: Commissioning of a novel 3 mm diameter cone for the ZAP-X system using a microSilicon detector

2585: Commissioning of a novel 3 mm diameter cone for the ZAP-X system using a microSilicon detector

Experimental and numerical investigation of transpiration cooling with gradient porosity layout for the thermal protection of nose cone

Transpiration cooling with liquid phase change has been widely regarded as one of the most promising thermal protection technology for aerospace vehicles. However, when applied to the nose cone with small curvature radius, cooling failure may occur due to the extreme high heat flux and pressure at the stagnation point. In order to deal with this issue, a wedged-shaped nose cone structures with a gradient porosity layout is designed in this work to optimize the coolant distribution in the porous nose cone, and the corresponding transpiration cooling performance with liquid phase change is experimentally and numerically investigated. At last, to meet the thermal protection requirements under different flight conditions as best as possible, an orthogonal experiment and fuzzy gray analysis were carried out to optimize the particle diameter, porosity layout and division interval of the porous nose cone with gradient porosity layout, taking a specific flight condition as an example. The results obtained in this work showed that gradient porosity layout can significantly improve the cooling efficiency at the stagnation point and the temperature uniformity on the outer surface. The porosity has the highest impact on the cooling performance, while the division interval has little impact. By optimizing, the cooling efficiency at the stagnation point can reach 74.5%, and the maximum temperature difference is less than 500K.

Utilization of hydrogen-diesel blends for the improvements of a dual-fuel engine based on the improved Taguchi methodology

A three-dimensional computational fluid dynamics model (CFD) of the diesel engine cylinder was developed using CONVERGE 3.0 software and a chemical reaction mechanism including 172 reactions and 62 components was developed using the CHEMKIN program. Then, the effects of nozzle diameter and spray cone angle on in-cylinder pressure, temperature, HC emission, NOx emission and soot emission of the hydrogen-diesel dual-fuel engine were investigated. Lastly, multi-objective optimization of HES, CR, nozzle diameter and spray cone angle were also carried out using Taguchi methodology. Analysis of variance and signal-to-noise ratio were performed using Minitab software. The results showed that higher in-cylinder pressure, temperature and NOx emission could be obtained with the decreasing nozzle diameters. But HC and soot emissions showed the opposite trend. Using the smaller spray cone angle was more favorable for in-cylinder pressure, temperature, HC, and NOx emissions. However, the small spray cone angle results in large amounts of soot emission. In addition, the factors that had the greatest impact on in-cylinder pressure, temperature, HC emission, and soot emission were all CR. And the factor that had the greatest impact on NOx emission was HES. This work provides a feasible technical approach to improve the marine diesel engine parameters.

Evolution rules for cathode erosion and corresponding arc behaviour in tungsten inert gas welding

Cathode erosion is a serious problem in long hours of Tungsten Inert Gas (TIG) welding. The evolution of electrode end shape and corresponding arc behaviour was studied at different welding currents and cathode parameters. The results illustrate that slow erosion, shedding, and expansion are three typical erosion modes. Slow erosion is an inevitable mode, causing the arc root width ( Ra) and arc diameter ( Rb) to slowly increase by 2.1% and 2.6%, respectively. With the increasing welding current or the decreasing cone angle and diameter, Ra and Rb are increased in shedding mode by 6.3% and 1.0%, respectively. Expansion appears when the electrode end has a truncated cone shape, causing gradual decrease of 5.7% and 2.3% in Ra and Rb, respectively.

Effect of mixing chamber structure on the performance of adjustable ejector

The study employs numerical simulation method to analyze performance of an adjustable ejector, with a specific focus on the influence of the structure dimension of mixing chamber. R41/R1234yf refrigerant is used as the working medium in the study. The primary and secondary flow inlets are set at the pressure of 1.4 MPa and 0.2 MPa, respectively, along with temperature of 353.15 K and 288.15 K corresponding. The outlet pressure of the ejector is 0.3 MPa. The simulation results show that optimal mixing chamber diameter within a range from 14.7mm to 18.7mm exists for obtaining peak adjustable ejector performance. Maximum entrainment ratio of 0.59 is obtained when cone diameter ratio is 65% and diameter of the mixing chamber is 15.7mm. Furthermore, the optimal mixing chamber length within range from 24mm to 220mm exists for obtaining peak adjustable ejector performance. Maximum entrainment ratio of 0.624 is obtained when cone diameter ratio is 76% and length of the mixing chamber is 88 mm. Therefore, it is crucial during designing process of the mixing chamber to ensure the complete fluid mixture and minimal flow resistance.

Dosimetric comparison of 6 MV and 10 MV flattening filter-free beams using small diameter cone for trigeminal neuralgia radiosurgery

Abstract Purpose: To compare the dosimetric characteristics and treatment delivery efficiency of trigeminal neuralgia (TN) stereotactic radiosurgery (SRS) patients previously treated with a 6 MV-FFF (flattening filter-free; radiation beam obtained by removing the flattening filter) beam versus those re-planned with a 10 MV-FFF beam using a conical collimator on the TrueBeam Novalis STx linear accelerator. Methods: Eleven patients with TN previously treated with a 6 MV-FFF beam following the SRS protocol of 90 Gy in a single fraction were selected. Plans were recalculated using 10 MV-FFF beam, maintaining the same dose prescription and beam angle configuration used with 6 MV-FFF beam. The dose gradient, volumes receiving 20 and 10 Gy, maximum dose and dose to 10% of the brainstem were recorded for both the energies. Efficiency was assessed by the average monitor unit (MU) and time per arc. The 10 MV-FFF machine was configured in the treatment planning system (TPS) to measure the tissue phantom ratio (TPR), dose profiles and scatter factors using RAZOR, PTW-60012 diodes and EBT3 radiochromic films. Results: Compared to the 6 MV-FFF, the 10 MV-FFF plans exhibit average increments in dose gradient, volume of 20 Gy and volume of 10 Gy of 3.8, 17.1 and 17.8%, respectively. Average increases of 6.5 and 18.1% were obtained for maximum dose and dose to 10% of the brainstem, respectively. An average increase of 31 MU/arc was observed for the 10 MV-FFF plans, with a 40% reduction in treatment time per arc. The TPR for the 10 MV-FFF beams increased by 10%, and a penumbra width of 0.3 mm was observed. Scatter factor increments of 15, 13.5, 12.7 and 10.3% were observed for the 6 MV-FFF over the 10 MV-FFF for cones of 4, 5, 6 and 7 mm, respectively. Conclusions: In TN SRS, the utilisation of 10 MV-FFF beams reduces treatment duration but results in an increased brainstem radiation dose. To mitigate this increase in brainstem dose, it is necessary to adjust the isocentre position.

Multi-Objective Optimization of a Long-Stroke Moving-Iron Proportional Solenoid Actuator.

In this study, the performance of a long-stroke moving-iron proportional solenoid actuator (MPSA) was improved by combining numerical simulations and experiments. A finite element model of the MPSA was developed; its maximum and mean relative absolute errors of electromagnetic force were 4.3% and 2.3%, respectively, under typical work conditions. Seven design parameters including the cone angle, cone length, depth of the inner hole of the coil skeleton, cone width of the armature, inner cone diameter, and initial position of the moving-iron core were selected for developing the model, and the coefficient of the variation in electromagnetic force, nominal acceleration, 95% of the maximum stable output electromagnetic force, and corresponding response time were used as the performance indicators. The constraint relation between each performance indicator and the influence of each design parameter on the performance indicators were revealed using the uniform Latin hypercube experiment design, correlation analysis, and the main effect analysis method. A multi-objective optimization mathematical model of the MPSA was developed by combining traditional surrogate and machine learning models. The Pareto solution set was obtained using the nondominated sorting genetic algorithm II (NSGA-II), and three decision schemes with different attitudes were determined using the Hurwicz multi-criteria decision-making method. The results showed that a strong contradiction exists among the 95% of the maximum stable output electromagnetic force and its corresponding response time and the coefficient of the variation in electromagnetic force. The cone angle considerably influenced the performance indicators. Compared with the initial design, the coefficient of the variation in electromagnetic force was reduced by 54.08% for the positive decision, the corresponding response time was shortened by 15.65% for the critical decision, and the corresponding acceleration was enhanced by 10.32% for the passive decision. Thus, the overall performance of the long-stroke MPSA effectively improved.