Axial Extraction Research Articles

Simulated investigation of a ku-band relativistic magnetron with modified all-cavity axial extraction at a low magnetic field

Since its invention in 1921 by Hull, magnetrons have undergone rapid development, transitioning from low-power devices to high-power relativistic magnetrons (RMs). However, research on RMs has been predominantly confined to L-X bands until now. To explore the potential of RM in higher frequency bands and align with the trend toward miniaturization of high-power microwave sources, a Ku-band RM has been investigated in this paper. Theoretical analysis dictates the selection of 24 cavities for optimal performance at a low magnetic field. Utilizing a three-dimensional particle-in-cell simulation platform, we demonstrate that the RM can generate a microwave power of 116 MW at a resonant frequency of 13.717 GHz with an electron beam of 126 kV and 2.0 kA, under a magnetic field of 0.22 T, corresponding to a power conversion efficiency of 46%. The integration of a modified all-cavity axial extraction structure in the Ku-band RM allows for a minimized inner radius of the magnetic field system to approximately 25 mm, while maintaining a high-power microwave output.

Axial peak extraction in the measurement of subsurface structures with annular illumination confocal microscopy

Abstract Three-dimensional dark-field confocal microscopy (DFCM) using annular illumination and complementary detection apertures is capable of detecting subsurface defects in ultra-precision optical components. In this study, a DFCM tuning algorithm for large apertures is proposed based on the sinc2 tuning model. This algorithm provides a reliable and theoretically accurate method for extracting the axial position during the measurement of subsurface defects. The rationality and accuracy of this method are verified through simulations and experimental results.

Finite element analysis and biomechanical study of "sandwich" fixation in the treatment of elderly proximal humerus fractures.

Proximal humerus fractures (PHFs) are common in the elderly and usually involve defects in the medial column.The current standard for medial column reconstruction is a lateral locking plate (LLP) in combination with either an intramedullary fibula support or an autogenous fibula graft. However, autogenous fibula graft can lead to additional trauma for patients and allogeneic fibular graft can increase patients' economic burden and pose risks of infection and disease transmission. The primary objective of this study was to introduce and assess a novel "Sandwich" fixation technique and compare its biomechanical properties to the traditional fixation methods for PHFs. In this study, we established finite element models of two different internal fixation methods: LLP-intramedullary reconstruction plate with bone cement (LLP-IRPBC) and LLP-intramedullary fibula segment (LLP-IFS). The biomechanical properties of the two fixation methods were evaluated by applying axial, adduction, abduction, torsional loads and screw extraction tests to the models. These FEA results were subsequently validated through a series of biomechanical experiments. Under various loading conditions such as axial, adduction, abduction, and rotation, the LLP-IRPBC group consistently demonstrated higher structural stiffness and less displacement compared to the LLP-IFS group, regardless of whether the bone was in a normal (Nor) or osteoporotic (Ost) state. Under axial, abduction and torsional loads, the maximum stress on LLPs of LLP-IRPBC group was lower than that of LLP-IFS group, while under adduction load, the maximum stress on LLPs of LLP-IRPBC group was higher than that of LLP-IFS group under Ost condition, and almost the same under Nor condition. The screw-pulling force in the LLP-IRPBC group was 1.85 times greater than that of the LLP-IFS group in Nor conditions and 1.36 times greater in Ost conditions. Importantly, the results of the biomechanical experiments closely mirrored those obtained through FEA, confirming the accuracy and reliability of FEA. The novel "Sandwich" fixation technique appears to offer stable medial support and rotational stability while significantly enhancing the strength of the fixation screws. This innovative approach represents a promising strategy for clinical treatment of PHFs.

Axial characteristic extraction algorithm of film cooling holes based on laser point cloud

Axial characteristic extraction algorithm of film cooling holes based on laser point cloud

Axial shift mapping: a self-referencing test for measuring the axial figure of near-cylindrical surfaces

Lateral shearing self-referencing interferometry methods shift the surface under test between measurements to separate its topography from that of the reference surface. However, rigid body errors occur during shifting, creating an ambiguity in the quadratic term of the extracted surfaces. We present axial shift mapping, a lateral shearing self-referencing interferometry method for cylinders, in which the quadratic ambiguity is resolved by measuring the rigid body errors using known artifact mirrors residing in the interferometer’s field of view. First, one-dimensional lines of a flat mirror are measured with 2.8 nm RMS difference compared to a three flat test. Then, axial shift mapping is extended to cylindrical surfaces using a computer generated hologram. We find that axial shift mapping results in full surface extraction of cylindrical optics, along the axial direction, with a repeatability of 4.4 nm RMS. We also find that the reference surface extracted through axial shift mapping is within 4.5 nm RMS of the transmitted wavefront error of the computer generated hologram substrate, which was expected to be the largest contribution of reference wavefront error.

Forced surgical extrusion using an axial tooth extraction system as a practicable technique for preserving severely destroyed teeth? - Clinical outcomes up to 4.8 years.

Several extrusion techniques have been described to restore teeth with insufficient coronal tooth structure and to avoid their extraction. Still, there is little evidence for a treatment concept combining surgical extrusion using an atraumatic axial extraction system. A total of nine patients, each with an iso- or subgingival fractured tooth, were retrospectively examined. Treatment of the damaged tooth comprised an atraumatic forced surgical extrusion performed with an axial tooth extraction system and a more coronal positioning within the socket. The teeth were initially splinted and subsequently restored. The follow-up period was up to 57.1 months and averaged 36.5 (SD: ±13.5) months. All nine teeth were still in situ, without signs of inflammation. During the period of the provisional restoration, six prosthetic complications occurred, which were resolved with little effort, whereas, success rate for the definitive restoration was 100%. No biological complications were observed concerning the root apex or soft tissue. The radiographically measured mean extrusion distance was 3.4 (SD: ±1.0) mm, so that a sufficient prosthetic ferrule could be reestablished. Surgical extrusions using an axial tooth extraction system demonstrate low biological and prosthetic complications rates over observation time. The presented extrusion approach preserves soft and hard tissue and is an efficient treatment option for severely destroyed teeth. Saving hopeless teeth by this relatively predictable and feasible procedure has hardly any disadvantages for patients, and in case of failure, an implant or fixed partial denture are still an option.

A Cross-Band Tunable Relativistic Magnetron With All Cavity Axial Extraction

A cross-band tunable relativistic magnetron (RM) with all-cavity axial extraction (ACAE) is presented. In this configuration, a single tuner with six sectorial metal plates is placed between the cavity and the extraction waveguide of a relativistic magnetron with all-cavity axial extraction (ACAE-RM) in the axial direction. The resonant frequency is tuned agilely by this tuner when it moves in the axial direction. Particle-in-cell (PIC) simulation results showed that this tube has a tuning range between 1.76 and 2.49 GHz, corresponding to a relative bandwidth of 34.3% about a center frequency of 2.125 GHz. A wideband horn antenna had been designed to radiate high-power microwave (HPM) in the desired frequency range for experimental research. Preliminary experimental research had been carried out that validated that the presented tunable RM has a wide tuning range. HPM oscillating from 1.79 to 2.55 GHz with power from 0.7 to 1.5 GW had been detected when the tube was tuned to specific parameters.

Effects of Nickel Plating on Interference Fit between Medium Carbon Steel and Copper–Zinc Alloy Parts

Studies on load capacity enhancement for an interference fit mainly focused on the essential coupling material pair of steel–steel parts. With more complex requirements in technical assemblies, more notable cases of material pairs are applied in interference fits. Hence, it is crucial to highlight the variations across-coupling scenarios in order to identify a workable approach for load capacity augmentation. The goal of this study is to examine how nickel plating affects the interference fit between steel and brass assembly parts. The experiments in this research focus on comparing the load capacity of plated and non-plated specimens by evaluating the extraction force on a compression machine. The fit parameters are measured with a coordinate measuring machine and contact surface profiler. Some microscopic observations are made to confirm the phenomena of this coupling case. The axial extraction tests determined that the plated fits show an increase in axial force limits of around 20% in comparison with the non-plated ones. There are also some significant improvements in the plated shaft surface properties, which reduce the physical adhesions between the shaft and hub. These results confirm the possibility of reusing the plated assembly parts, which gives highly economic and environmental advantages.

Research on fault diagnosis method of turbocharger rotor based on Hu-SVM-RFE

Abstract Several parameters need to be monitored for turbocharger rotor faults and the overlap between different fault parameters as well as the redundancy of data, which leads to increased calculation time and reduced classification accuracy. To improve the recognition rate of turbocharger rotor faults, a recursive elimination method based on the support vector machine-recursive feature elimination (SVM-RFE) combined with improved Hu invariant moments is developed for the axial orbit feature extraction of turbocharger rotor with rotor fault. Firstly, improved Hu-invariant moments are extracted for different rotor fault axis orbits, and then the feature ranking and selection are performed by the SVM-RFE method to filter out the feature combinations with higher classification recognition rates. Then, the feature matrix of the Hu-SVM-RFE algorithm screening combination was identified for classification using each of the three diagnostic algorithms. The results show that the optimal feature subset obtained by the Hu-SVM-RFE method can ensure the richness of the fault information of the turbocharger rotor with small number of features. And, a high classification rate can be obtained with low time consumption in combination with the probabilistic neural network (PNN) algorithm. Therefore, Hu-SVM-RFE feature screening method combined with PNN fault diagnosis technology has high accuracy and efficiency, which is of great significance for online fault identification of the supercharger rotor.

CGBO-Net: Cruciform structure guided and boundary-optimized lymphoma segmentation network

Lymphoma segmentation plays an important role in the diagnosis and treatment of lymphocytic tumor. Most current existing automatic segmentation methods are difficult to give precise tumor boundary and location. Semi-automatic methods are usually combined with manually added features such as bounding box or points to locate the tumor. Inspired by this, we propose a cruciform structure guided and boundary-optimized lymphoma segmentation network(CGBS-Net). The method uses a cruciform structure extracted based on PET images as an additional input to the network, while using a boundary gradient loss function to optimize the boundary of the tumor. Our method is divided into two main stages: In the first stage, we use the proposed axial context-based cruciform structure extraction (CCE) method to extract the cruciform structures of all tumor slices. In the second stage, we use PET/CT and the corresponding cruciform structure as input in the designed network (CGBO-Net) to extract tumor structure and boundary information. The Dice, Precision, Recall, IOU and RVD are 90.7%, 89.4%, 92.5%, 83.1% and 4.5%, respectively. Validate on the lymphoma dataset and publicly available head and neck data, our proposed approach is better than the other state-of-the-art semi-segmentation methods, which produces promising segmentation results.

Analysis of mode excitation of a relativistic magnetron with azimuthal-periodic-cavity extraction

Relativistic magnetron (RM) with all cavity-magnetron axial extraction (ACMAE) has attracted much attention, benefiting from its good performance. In this paper, RM with ACMAE is generalized to a general case called RM with azimuthal-periodic-cavity extraction due to the introduction of two structure parameters of R and S, where R indicates the number of cavities between the two extraction cavities in a coupling waveguide and S indicates the number of cavities between two adjacent coupling waveguides. The necessary conditions for mode excitation of the RM are theoretically investigated and verified by simulations. Using the expression of the necessary conditions, one can easily figure out the output mode components of the RM in theory according to the structural parameters and the number of electron spokes. This new technique provides more solving schemes with different extraction structures for designing high performance RMs with different advantages in applications of high power microwave.

MILLIMETER-WAVELENGTH RELATIVISTIC MAGNETRON: PROBLEMS OF MICROWAVE POWER EXTRACTION

The relativistic magnetrons operating at millimeter wavelengths demonstrate problems with microwave power extraction, both in the radial and in axial direction. The preferred axial extraction concept can be implemented ei-ther as ‘diffractional output’ or via introduction of additional resonant elements into the output waveguide. In this paper several solutions for axial-directed extraction are discussed, including circular ring ‘antennas’ at the end of the anode-cathode space, and resonance-length rods at the faces of the anode-block cavities. These have allowed increasing the power extraction efficiency by a factor of 101 to 102.

An Improved Compact and High-Efficiency Relativistic Magnetron With TE11 Mode Radiation

An improved compact and high-efficiency A6 relativistic magnetron (RM) with axial extraction is proposed and studied by numerical simulations. Compared with the conventional design, two pairs of diametrically opposite cavities (four cavities) of the anode block are tapered onto the horn antenna for TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode radiation with high output efficiency. Due to the cutoff radius of the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode is the smallest in the circular waveguide, the diameter of the output waveguide could be reduced obviously. And the total axial length of the horn antenna could also be shortened accordingly. At the same time, a semitransparent cathode is used for quick startup and efficient beam-wave interaction. Results of the 3-D particle-in-cell (PIC) simulations show that over 1.25 GW output power with TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode is obtained at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> -band, when the electron beam voltage is 600 kV and the applied axial guiding magnetic field is 0.54 T. And the efficiency exceeds 66%. Simulation results also show that the output efficiency of the proposed RM keeps almost unchanged between 550 and 620 kV with fixed guiding magnetic field.

Evaluation of post-extraction healing after atraumatic axial tooth extraction using Benex system II versus conventional extraction: Randomized control trial

Background and PurposeTooth extraction is critical for dental treatment complications. One of the most discussed topics is socket healing after extraction. The Benex system allows extraction without causing unnecessary socket expansion by removing the tooth vertically, preserving both bone and soft tissue. AimTo assess postoperative healing signs, symptoms, and complications using the Benex extraction system and compare it with conventional extraction among patients at Umm Al-Qura University. MethodsThirty-eight patients with hopeless single-rooted teeth were included. They were divided into two equal groups: one in which teeth were extracted using the conventional method and one in which extractions were performed by Benex. The Benex system for tooth extraction was performed by drilling into the root canal, followed by screw insertion. Once the extractor was properly positioned, extraction was accomplished by turning the hand screw clockwise. At baseline, the wound size was evaluated. On days 1, 3, and 7 after extraction, telephone interviews were conducted to evaluate pain and post-extraction complications using a pain scale and questionnaire. Socket healing and wound size were evaluated after 2 and 4 weeks of extraction using the healing index and H2O2 epithelization test. ResultsThe Benex extraction system accelerated early soft-tissue healing and decreased pain and wound size compared with the control group. Conclusion. The Benex system is relatively safe and easy to use, but this does not eliminate the need for a degree of education and training. Proper selection of the case, knowledge of using the device, and implementation of that knowledge in the treatment planning are important factors in ensuring success with this system.

Compact High Efficiency Relativistic Magnetron With TE11 Mode Output

A compact high-efficiency GW-level <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> -band relativistic magnetron (RM) with TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode output is proposed. In order to achieve high efficiency and high power, an eight-cavity slow wave system with rectangular vanes is adopted, which can provide a larger resonant system where the high-frequency energy is directly stored. All cavity axial extraction (ACAE) is applied with four 90° sector waveguides arranged azimuthally around the anode block. The four 90° sector waveguides play a significant role in converting sector waveguide TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode to circular waveguide TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode. The entire tube is designed without any increase in the radial dimension, which is propitious to a compact and lightweight magnet system design. In particle-in-cell (PIC) simulations, the proposed rectangular vane-type 8-cavity (R8) RM with ACAE can generate a microwave power of 2.1 GW with a pure TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode at the frequency of 2.475 GHz when the applied voltage is 460 kV and the axial magnetic field is 0.46 T, and the power conversion efficiency is 68.4%.

Efficient Relativistic Magnetron With a Split Cathode

An ${L}$ -band all cavity axial extraction (ACAE) relativistic magnetron (RM) with a split cathode is proposed. The proposed RM is driven by virtual cathode that formed by axial flow of electrons from two conical emitters at both sides of slow wave structure, which is different from other RM that powered by radial flow of electrons from a cathode inside the interaction region. This cathode structure is simple but practical to generate a squeeze state electron in an RM with almost all the output structure. To improve the output performance, the anode blocks are modified with additional sections at both ends. Particle-in-cell (PIC) simulation results illustrate that when this tube is applied with a diode voltage of 600 kV, an average output microwave power of 1.6 GW can be obtained. Comparing with ACAE-RM using a conventional transparent cathode, the power conversion efficiency is improved from 47% to 67%.

Characterization of Acetabular Cup Insertion Forces in Cancellous Bone Proxy for Validation of an Invasive Sensing Model and Development of Automatic Prosthesis Installation Device: A Preliminary Study

Abstract Total hip replacement is a widespread medical procedure, with over 300,000 surgeries performed each year in the United States alone. The vast majority of total hip replacements utilize press fit fixation. Successful seating of the implant requires a delicate balance between inserting the implant deep enough to obtain sufficient primary stability, while avoiding fracture of bone. To improve patient outcomes, surgeons need assistive technologies that can guide them as to how much force to apply and when to stop impacting. The development of such technology, however, requires a greater understanding of the forces experienced in bone and the resulting cup insertion and implant stability. Here, we present a preliminary study of acetabular cup insertion into bone proxy samples. We find that as the magnitude of force on the acetabular cup increases, cup insertion and axial extraction force increase linearly, then nonlinearly, and finally plateau with full insertion. Within the small nonlinear zone, approximately 90% of both cup insertion and extraction force are achieved with only 50% total energy required for full seating, posing the question as to whether full seating is an appropriate goal in press-fit arthroplasty. For repeated impacts of a given energy, cup displacement and force experienced in bone (measured force profile—MFP) increase correspondingly and reach a plateau over a certain number of impacts (number of impacts to seating—NOITS), which represents the rate of insertion. The relationship between MFP and NOITS can be exploited to develop a force feedback mechanism to quantitatively infer optimal primary implant stability.

Electromagnetic and Particle-In-Cell Simulation of 5-mW-Long Anode Pulse Magnetron

An electromagnetic (EM) and particle-in-cell (PIC) simulation studies have been carried out to virtual prototype an unstrapped 12 resonator (hole and slot type) 5-MW-long anode magnetron (LAM) with axial extraction symmetrical output (AESO) using 3-D code Computer Simulation Technology, Microwave and Particle Studio (CST-MWS and CST-PS). The “admittance matching theory” and a “length-optimization algorithm” have been used for the selection and optimization of the dimensional parameters of the LAM anode block. The role of AESO has been investigated in the context of mode conversion and output coupling. The designed LAM has a cold frequency of 2.868 GHz with axial mode separation of 268 MHz (9.34% of design frequency). $f_{\pi \prime }/f_{\pi } = 1.093$ and $f_{\pi -1}/f_{\pi } = 0.998$ along with the circuit efficiency of 91.5% have been achieved. The saturated output power is 5.2 MW with an anode voltage of 55 kV and anode current of 205 A. The hot frequency of the LAM is 2.841 GHz with an interaction efficiency of 46.1%. The simulation results have been validated with experimental results of the commercially available E2V LAM tube (M5028).

Compact Dual-Frequency Relativistic Magnetron With TEM Mode Output

We propose a compact dual-frequency relativistic magnetron with TEM mode output. The resonant system consists of two axially separated beam–wave interaction regions for generating dual-frequency microwave. Under the same diode voltage and axial magnetic field, the RF field of the operating $\pi $ -mode can almost be simultaneously established. Furthermore, the diffraction output and the all cavity axial extraction are integrated to realize the TEM mode output. Particle-in-cell simulation shows that when the diode voltage is 400 kV, microwaves with output powers of 740 and 876 MW generate, with frequencies of 2.05 and 2.35 GHz, respectively. With an axial magnetic field of 0.44 T, the device efficiency of over 43% in the dual-frequency relativistic magnetron is achieved.

An Efficient All Cavity Axial Extraction Relativistic Magnetron With Virtual Cathode

A compact and high-efficiency ${L}$ -band relativistic magnetron (RM) with all cavity axial extraction (ACAE) driven by a virtual cathode is proposed. Electron beam current produced by explosive emission cathode is controlled below space-charge-limited current to reduce electron energy dissipation before interaction region, and a low-energy state of electrons with the potential close to a physical cathode potential in an RM is formed by magnetic mirror and an external cathode. The particle-in-cell (PIC) simulation demonstrates that the proposed RM could output a pure TM01 mode at the frequency of 1.63 GHz with gigawatt radiation power, and power conversion efficiency is improved from 47% to 65% when it is compared with an ACAE-RM with the same anode structure using transparent cathode.