bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field-programable-gate-array-based distributed coincidence processor for high count-rate online positron emission tomography coincidence data acquisition
Authors: Cheng Xinyi , Hu Kun , Yang Dongxu , Shao Yiping 
Published: January 2021

Abstract
For positron emission tomography (PET) online data acquisition, a centralized coincidence processor (CCP) with single-thread data processing has been used to select coincidence events for many PET scanners. A CCP has the advantages of highly integrated circuit, compact connection between detector front-end and system electronics and centralized control of data process and decision making. However, it also has the drawbacks of data process delay, difficulty in handling very high count-rates of single and coincidence events and complicated algorithms to implement. These problems are exacerbated when implementing a CCP on a field-programable-gate-array (FPGA) due to increased routing congestion and reduced data throughput. Industry companies have applied non-centralized or distributed data processing to solve these problems, but those solutions remain either proprietary or lack full disclosure of technical details that make the techniques unclear and difficult to adapt for most research communities. In this study, we investigated the use of a set of distributed coincidence processors (DCP) that can address the CCP problems and be implemented relatively easily. Each coincidence processor exclusively connects one detector pair and selects coincidence events from this detector pair only, which breaks a centralized coincidence process to a collection of independent and parallel processes. DCP can significantly minimize the data process delay, maximize count-rates of coincidence events and simplify implementation by implementing a single coincidence processor with one detector pair and replicating it to the rest. A prototype DCP with 42 coincidence processors was implemented on an off-the-shelf FPGA development board for a small PET with 12 detectors configured with 42 detector pairs. DCP performances were tested with both pulsed signals and gamma ray interactions. There was no coincidence data loss up to the detector’s maximum singles count-rate (250 k s−1). Approximately 1.2 k registers were utilized for each coincidence processor and the FPGA resource utilization was proportional to the number of coincidence processors. Coincidence timing spectra showed the results from accurately acquired coincidence events. In conclusion: complementary to CCP, DCP can provide high count-rate capability, with a simplified algorithm for implementation and potentially a practical solution for online acquisition of a PET with a larger number of detector pairs or for ultrahigh-throughput imaging.
Long-length tomosynthesis and 3D-2D registration for intraoperative assessment of spine instrumentation
Authors: Zhang Xiaoxuan , Uneri Ali , Wu Pengwei , Ketcha Michael D , Jones Craig K , Huang Yixuan , Lo Sheng-Fu Larry , Helm Patrick A , Siewerdsen Jeffrey H 
Published: January 2021

Abstract

Purpose. A system for long-length intraoperative imaging is reported based on longitudinal motion of an O-arm gantry featuring a multi-slot collimator. We assess the utility of long-length tomosynthesis and the geometric accuracy of 3D image registration for surgical guidance and evaluation of long spinal constructs. Methods. A multi-slot collimator with tilted apertures was integrated into an O-arm system for long-length imaging. The multi-slot projective geometry leads to slight view disparity in both long-length projection images (referred to as ‘line scans’) and tomosynthesis ‘slot reconstructions’ produced using a weighted-backprojection method. The radiation dose for long-length imaging was measured, and the utility of long-length, intraoperative tomosynthesis was evaluated in phantom and cadaver studies. Leveraging the depth resolution provided by parallax views, an algorithm for 3D-2D registration of the patient and surgical devices was adapted for registration with line scans and slot reconstructions. Registration performance using single-plane or dual-plane long-length images was evaluated and compared to registration accuracy achieved using standard dual-plane radiographs. Results. Longitudinal coverage of ∼50–64 cm was achieved with a single long-length slot scan, providing a field-of-view (FOV) up to (40 × 64) cm2, depending on patient positioning. The dose-area product (reference point air kerma × x-ray field area) for a slot scan ranged from ∼702–1757 mGy·cm2, equivalent to ∼2.5 s of fluoroscopy and comparable to other long-length imaging systems. Long-length scanning produced high-resolution tomosynthesis reconstructions, covering ∼12–16 vertebral levels. 3D image registration using dual-plane slot reconstructions achieved median target registration error (TRE) of 1.2 mm and 0.6° in cadaver studies, outperforming registration to dual-plane line scans (TRE = 2.8 mm and 2.2°) and radiographs (TRE = 2.5 mm and 1.1°). 3D registration using single-plane slot reconstructions leveraged the ∼7–14° angular separation between slots to achieve median TRE ∼2 mm and <2° from a single scan. Conclusion. The multi-slot configuration provided intraoperative visualization of long spine segments, facilitating target localization, assessment of global spinal alignment, and evaluation of long surgical constructs. 3D-2D registration to long-length tomosynthesis reconstructions yielded a promising means of guidance and verification with accuracy exceeding that of 3D-2D registration to conventional radiographs.
Accelerated 3D image reconstruction with a morphological pyramid and noise-power convergence criterion
Authors: Sisniega A , Stayman J W , Capostagno S , Weiss C R , Ehtiati T , Siewerdsen J H 
Published: January 2021

Abstract
Model-based iterative reconstruction (MBIR) for cone-beam CT (CBCT) offers better noise-resolution tradeoff and image quality than analytical methods for acquisition protocols with low x-ray dose or limited data, but with increased computational burden that poses a drawback to routine application in clinical scenarios. This work develops a comprehensive framework for acceleration of MBIR in the form of penalized weighted least squares optimized with ordered subsets separable quadratic surrogates. The optimization was scheduled on a set of stages forming a morphological pyramid varying in voxel size. Transition between stages was controlled with a convergence criterion based on the deviation between the mid-band noise power spectrum (NPS) measured on a homogeneous region of the evolving reconstruction and that expected for the converged image, computed with an analytical model that used projection data and the reconstruction parameters. A stochastic backprojector was developed by introducing a random perturbation to the sampling position of each voxel for each ray in the reconstruction within a voxel-based backprojector, breaking the deterministic pattern of sampling artifacts when combined with an unmatched Siddon forward projector. This fast, forward and backprojector pair were included into a multi-resolution reconstruction strategy to provide support for objects partially outside of the field of view. Acceleration from ordered subsets was combined with momentum accumulation stabilized with an adaptive technique that automatically resets the accumulated momentum when it diverges noticeably from the current iteration update. The framework was evaluated with CBCT data of a realistic abdomen phantom acquired on an imaging x-ray bench and with clinical CBCT data from an angiography robotic C-arm (Artis Zeego, Siemens Healthineers, Forchheim, Germany) acquired during a liver embolization procedure. Image fidelity was assessed with the structural similarity index (SSIM) computed with a converged reconstruction. The accelerated framework provided accurate reconstructions in 60 s (SSIM = 0.97) and as little as 27 s (SSIM = 0.94) for soft-tissue evaluation. The use of simple forward and backprojectors resulted in 9.3× acceleration. Accumulation of momentum provided extra ∼3.5× acceleration with stable convergence for 6–30 subsets. The NPS-driven morphological pyramid resulted in initial faster convergence, achieving similar SSIM with 1.5× lower runtime than the single-stage optimization. Acceleration of MBIR to provide reconstruction time compatible with clinical applications is feasible via architectures that integrate algorithmic acceleration with approaches to provide stable convergence, and optimization schedules that maximize convergence speed.
Application of lung substitute material as ripple filter for multi-ion therapy with helium-, carbon-, oxygen-, and neon-ion beams
Authors: Inaniwa Taku , Abe Yasushi , Suzuki Masao , Lee Sung Hyun , Mizushima Kota , Nakaji Taku , Sakata Dousatsu , Sato Shinji , Iwata Yoshiyuki , Kanematsu Nobuyuki , Shirai Toshiyuki 
Published: January 2021

Abstract
A development project for hypo-fractionated multi-ion therapy has been initiated at the National Institute of Radiological Sciences in Japan. In the treatment, helium, carbon, oxygen, and neon ions will be used as primary beams with pencil beam scanning. A ripple filter (RiFi), consisting of a thin plastic or aluminum plate with a fine periodic ridge and groove structure, has been used to broaden the Bragg peak of heavy-ion beams in the beam direction. To sufficiently broaden the Bragg peak of helium-, carbon-, oxygen-, and neon-ion beams with suppressed lateral scattering and surface dose inhomogeneity, in this study, we tested a plate made of a lung substitute material, Gammex LN300, as the RiFi. The planar integrated dose distribution of a 183.5 MeV u−1 neon-ion beam was measured behind a 3 cm thick LN300 plate in water. The Bragg peak of the pristine beam was broadened following the normal distribution with the standard deviation σ value of 1.29 mm, while the range of the beam was reduced by 8.8 mm by the plate. To verify the LN300 performance as the RiFi in multi-ion therapy, we measured the pencil beam data of helium-, carbon-, oxygen- and neon-ion beams penetrating the 3 cm thick LN300 plate. The data were then modeled and used in a treatment planning system to achieve a uniform 10% survival of human undifferentiated carcinoma cells within a cuboid target by the beam for each of the different ion species. The measured survival fractions were reasonably reproduced by the planned ones for all the ion species. No surface dose inhomogeneity was observed for any ion species even when the plate was placed close to the phantom surface. The plate made of lung substitute material, Gammex LN300, is applicable as the RiFi in multi-ion therapy with helium-, carbon-, oxygen- and neon-ion beams.
Electrical modeling of cylindrical dielectric elastomer transducers
Authors: van Kessel R , Bauer P , Ferreira J A 
Published: January 2021

Abstract
Dielectric elastomer transducers (DETs) are commonly modeled by lumped-element models (LEMs), however such models do not capture the cutoff behavior that manifests at relatively low frequencies due to the high resistivity of the stretchable electrodes. Moreover, the contribution of the electrodes into the lumped series resistance is not accurately known. The aim of this work is to define the accuracy and frequency limits of the LEM and to derive the exact values of its lumped components. This is achieved by developing a detailed three-dimensional distributed-element model (DEM) of the transducer structure. Based thereon, analytical expressions are developed for the LEM components and limits are explored. Through numerical evaluation of the DEM it is found that only two-third of the single-polarity electrode resistance contributes to the lumped series resistance, which is three times lower than predicted by existing models. Comparison between the LEM and DEM further shows that the LEM is adequate for frequencies significantly below the cutoff frequency. Thereafter, capacitance and resistance fall off as a result of signal propagation limitations. This has been experimentally verified. The developed DEM and established validity range of the simple LEM allows for more accurate sensors and better optimized transducers designs, with up to three times less electrode material.
Predictive vision of development paths of pump technical systems
Authors: Kovaliov I A , Ratushnyi A V , Dzafarov T V , Mandryka A S , Ignatiev A S 
Published: January 2021

Abstract
In the work on the basis of objective laws on the development of technical systems and the features of the VI technological order directions of further development of pump technical systems are analyzed. The reserves of systems that already exist without changing the principle of the working process are shown, the concept of "combined working process" is introduced and the question of the necessity and possibility of searching for fundamentally different physical processes of liquid power transfer, including at the micro level, is raised.
The influence of the design parameters of the rotors of the planetary hydraulic motor on the change in the output characteristics of the mechatronic system
Authors: Panchenko A , Voloshina A , Titova O , Panchenko I 
Published: January 2021

Abstract
One of the main stages of research related to increasing the efficiency of planetary hydraulic motors operating as part of the mechatronic systems of self-propelled vehicles is the experimental research of real samples. Experimental studies of the influence of design features of the rotor system of serial and modernized hydraulic motors on the output characteristics of mechatronic systems were carried out by means of comparative bench tests. A technique has been developed for conducting comparative bench studies of planetary hydraulic motors. A test bench scheme is proposed for testing a family of unified series of high-torque, low-speed planetary-type hydraulic motors. The main factors determining the change in the output characteristics of the planetary hydraulic motor, taking into account the design features of the rotor system, are: pressure drop, flow rate of the working fluid and the error the manufacturing form of the gear profile of its rotors. Tests of planetary hydraulic motors with a serial and modernized rotor systems were carried out. The modernization of the rotor system was carried out by changing the design of the external and internal rotors in order to reduce the shape error of their gear profile. As a result of experimental studies, it was found that eliminating the error the manufacturing form of the rotors of the modernized hydraulic motor can significantly improve its output characteristics - increase the torque at specified rotation speeds, and as a result, increase the hydromechanical and overall efficiency of the mechatronic system as a whole.
A numerical solution of temperature distribution in the clearance and the sealing rings of the non-contact face seal
Authors: Dindorf R , Wos P 
Published: January 2021

Abstract
The study presents a numerical analysis of the temperature distribution in the clearance and the temperature distribution in the rings of a non-contact face seal. Non-contact face seals designed for turbine pumps to meet the requirements of lower leakage, longer life, and more frequent starting and stopping are included in this test. A thermo-hydro-mechanical model of the non-contact face seal clearance has been presented. Based on this model, dimensionless differential equations were derived to determine the temperature distribution in the clearance seal gap and the temperature distribution in sealing rings. The numerical solution of differential equations allowed the presentation of temperature characteristics for different parameters of the analyzed non-contact face seal. The analysis took into account hydrodynamic and thermodynamic phenomena in the clearance of the face seal depending on pressure, leakage flow rate and temperature of the sealing fluid, clearance dimensions, thermal parameters of the sealing rings, and operation parameters of the rotating machine. The temperature distribution in a non-contact face seal can also be used to determine the thermal deformation of the sealing rings. The presented numerical model is useful in the design of non-contact face seals because it allows the selection of parameters stabilizing the thermo-hydro-mechanical state of the two mating sealing rings.
Determination of angular stiffness coefficient of the annular seal by experiment-calculation
Authors: Gorovoy S , Golovchenko G , Dumanchuk M 
Published: January 2021

Abstract
Hydrodynamic forces in annular seals of centrifugal pumps create a significant effect on the vibrational activity of the rotor as a whole. Theoretical and experimental studies of various authors made it possible to establish the structure of hydrodynamic forces and determine the magnitude of the coefficients of radial forces. The authors of this work obtained quantitative load characteristics of the rotor in an annular seal at specially created laboratory experimental stands at various pressure drops and significant angles of misalignment of the rotor axis relative to the seal axis. Static experiments were also conducted with annular seals of various lengths with a constant differential pressure of the liquid and a fixed angle of misalignment of the rotor axis relative to the axis of the annular seal. The given misalignment angle was obtained as a result of the action of various external forces on the rotor. In addition to static experiments, dynamic rotor tests were carried out. Experimentally obtained amplitude - frequency characteristics of the forced radial - angular oscillations of the rotor, which is dynamically mounted in two symmetrical annular seals. From the experimental characteristics, the critical frequency of the rotor angular oscillations in the seals was determined. According to theoretical formulas, taking into account the value of the coefficient of angular stiffness of the annular seal, the frequency of the natural angular oscillations of the rotor in the annular seals was calculated. A comparison of theoretical and experimental values indicates their good quantitative agreement.
Magnetic field in the core of a magnetic fluid seal taking magnetic structural elements into account
Authors: Radionov A V , Podoltsev A D , Radionova A A 
Published: January 2021

Abstract
According to the results of the finite element analysis of the magnetic field of the liquid metal seal designed to protect the bearing assembly from external aggressive influences, it is shown that its mounting directly on the bearing shield having magnetic properties leads to an increase in magnetic fluxes of scattering and to a decrease in the peak value of magnetic induction in the working the gap from 1, 6 T to 1,1 T., i.e. to a decrease of 31%. The use of a non-magnetic insert between the seal and the bearing assembly allows this induction to be increased. The dependence of this induction on the thickness of the insert is given, which makes it possible to choose its rational value when installing the seal. It is shown that the use of an additional permanent magnet located in the area of this insert allows one to increase the peak value of magnetic induction in the working gap from 1.3 T to 1.75 T and, as a result, improve the performance of the seal.
New technology for restoring Babbitt coatings
Authors: Konoplianchenko Ie , Tarelnyk V , Martsynkovskyy Vas , Gaponova O , Lazarenko A , Sarzhanov A , Mikulina M , Zhengchuan Zh , Pirogov V 
Published: January 2021

Abstract
The reasons for reducing the durability of sliding bearings and the factors formed both at the stage of their manufacture and during operation are considered. Taking into account the types of destruction of sliding bearing coatings (exfoliation, disintegration of individual sections, field failure) the need for developing technological recommendations for their repair is demonstrated. The analysis of existing technological methods for restoring worn surfaces of parts is shown. The technique for applying the method of electrospark alloying to repair bearing liners is represented. The technologies of applying combined electrospark coatings to increase the adhesion strength of the substrate to the antifriction Babbit layer are described. There have been revealed the correlation dependences of the quality characteristics of the Babbit coatings restored by the method of electrospark alloying versus the technological parameters of the process. This makes it possible to significantly implement the methodology for controlling the surface layer quality while manufacturing and repairing the products with Babbit coatings. A technique has been developed for determining the mass transfer equation constants and for predicting the roughness. The mathematical models have been proposed to specify the quality parameters of the layers being formed in the course of the Babbit coating restoration based on the energy parameters of the electrospark alloying plant.
Computational study of the effect of pump mounting to foundation compliance on pump natural frequencies
Authors: Yashchenko A , Verbovyi A , Rudenko A 
Published: January 2021

Abstract
This article deals with the development of more accurate models of high-performance pump machines, which are mounted onto the foundation by means of compliant supports. These models demonstrate dependence between support foundation compliance and dynamics of pump elements such as rotor, pump casing and casing of pump bearings. After application of these approaches, the method of vibrational calculation with variable values of support compliance taken into account is provided. This task has been performed by using the multifunctional program complex ANSYS Workbench. In particular, the investigation employs the Modal Analysis subprogram, which implements the finite element method at the tasks of vibration analysis of constructions. The degree of effect of pump baseplate compliance on the rotor dynamics behaviour has been determined. Data charts of dependencies of rotor, pump casing and bearing housings natural frequencies on pump mounting to foundation compliance have been obtained.
Analysis of elastic supports and rotor flexibility for dynamics of a cantilever impeller
Authors: Tkachuk M M , Grabovskiy A , Tkachuk M A , Zarubina A , Lipeyko A 
Published: January 2021

Abstract
Turbochargers of modern internal combustion engines experience severe service conditions. In particular the compressor impeller is driven at extremely high angular velocity (30,000 rpm and more). Furthermore the increased requirements for the air intake dictate ever larger dimensions of the rotor disk up to 250 mm. These two factors lead to a pressing problem of stiffness, strength and dynamic stability of the newly designed units. This problem is analyzed with the help of a newly created parametric model of cantilever impeller rotor dynamics. This model accounts for the flexibility of the drive shaft and the impeller disk, quasistatic inertial and aerodynamic loads. The rotordynamics analysis is performed with a specific focus on the support behavior. The effect of initial gap and resilient characteristics of bearings and bushings is taken into account. As a result various components of displacements can be evaluated for different values of the disk diameter and angular velocity. It is critical for the design that neither radial nor axial displacement should not exceed given bounds. Furthermore, critical speeds of the studied rotor system have been determined for the various configurations of the disk and shaft dimensions. The proposed solution is to lower the first one or two eigenfrequencies of the system below the operating domain, so that the rotor becomes stable to any external excitations. Altogether, the developed mechanical analysis tool has proved itself as a useful tool for the engineering practice that allows to eliminate fatal flaws at early design stages.