bluuebunny/crossref_metadata_2025_split huggingface dataset:
Teaching large angle pendulum via Arduino based STEM education material
Authors: Erol Mustafa , Oğur Mehmet 
Published: May 2023

Abstract
This study reports an Arduino based STEM education material that resolves large angle pendulum, alternatively anharmonic oscillator, both experimentally and theoretically, particularly focuses on the time dependence of the instantaneous displacement angles. Instantaneous time dependence of the angles is experimentally measured by using Arduino Nano microprocessor connected to a gyro sensor and a bluetooth transmitter/receiver structured as a STEM education material. Theoretical resolution of the large angle pendulum is also accomplished by considering the approximate solution taking into account the relevant frictional effects. The theoretical and experimental resolutions are managed for the initial angles of

θ
0

=
1.40

rad

and

θ
0

=
2.61

rad

, specifically focusing on the angular frequencies, frictional effects and anharmonicity of the motion. The relative errors concerning the angular frequency are found to be % 15.2 and % 6.5 for

θ
0

=
2.61

rad

and

θ
0

=
1.40

rad

, respectively. The exponential decrease due to the frictional effects are in perfect agreement with each other and providing a friction coefficient of

γ
=
0.015

kg m

s

−
1

for both experimental and theoretical results. The anharmonicity of the pendulum is also illustrated by comparing the experimental plots and relevant theoretical plots for the small angle approximations. This work offers a prototype teaching material which can create an education environment where students can feel dynamic and encompass the acquisitions of Science Technology Engineering and Mathematics.
A graphical user interface for calculating the arterial input function during dynamic positron emission tomography
Authors: Daoud Youstina , Carroll Liam , Enger Shirin A 
Published: May 2023

Abstract

Purpose. Dynamic positron emission tomography (dPET) requires the acquisition of the arterial input function (AIF), conventionally obtained via invasive arterial blood sampling. To obtain the AIF non-invasively, our group developed and combined two novel solutions consisting of (1) a detector, placed on a patient’s wrist during the PET scans to measure the radiation leaving the wrist and (2) a Geant4-based Monte Carlo simulation software. The simulations require patient-specific wrist geometry. The aim of this study was to develop a graphical user interface (GUI) allowing the user to import 2D ultrasound scans of a patient’s wrist, and measure the wrist features needed to calculate the AIF. Methods. The GUI elements were implemented using Qt5 and VTK-8.2.0. The user imports a patient’s wrist ultrasound scans, measures the radial artery and veins’ surface and depth to model a wrist phantom, then specifies the radioactive source used during the dPET scan. The phantom, the source, and the number of decay events are imported into the Geant4-based Monte Carlo software to run a simulation. In this study, 100 million decays of 18F and 68Ga were simulated in a wrist phantom designed based on an ultrasound scan. The detector’s efficiency was calculated and the results were analyzed using a clinical data processing algorithm developed in a previous study. Results. The detector’s total efficiency decreased by 3.5% for 18F and by 51.7% for 68Ga when using a phantom based on ultrasound scans compared to a generic wrist phantom. Similarly, the data processing algorithm’s accuracy decreased when using the patient-specific phantom, giving errors greater than 1.0% for both radioisotopes. Conclusions. This toolkit enables the user to run Geant4-based Monte Carlo simulations for dPET detector development applications using a patient-specific wrist phantom. Leading to a more precise simulation of the developed detector during dPET and the calculation of a personalized AIF.
Evaluation of a modular all-in-one high-resolution PET detector and readout electronics setup
Authors: Schmidt F P , Krämer J C , Parl C , Schmand M , Pichler B J 
Published: May 2023

Abstract

Objective. The all-in-one solution and modularity of the C13500 series TOF-PET detector modules (Hamamatsu Photonics K.K., Hamamatsu, Japan) make them a highly attractive candidate for the development of positron emission tomography (PET) systems. However, the commercially available portfolio targets clinical whole-body PET systems with a scintillation crystal cross area of 3.1 × 3.1 mm2. To extend the modules for high resolution (preclinical or organ specific) systems, the support for smaller scintillation crystals is required. Approach. In this work, a PET detector was developed based on the TOF-PET modules using a light sharing approach, 16 × 16 lutetium oxyorthosilicate (LSO) scintillation crystals with a size of 1.51 × 1.51 × 10.00 mm3 readout with 8 × 8 photosensor channels of size 3.0 × 3.0 mm2. In addition to hardware and software development, the optimized parameter settings for the adapted configuration were evaluated. Main Results. A factor of two in amplification of the analog signal compared to the minimum gain setting was necessary for an accurate crystal identification (peak-to-valley ratio 14.9 ± 5.9). A further increase to a factor of three was not determined as optimum as the time over threshold duration, thus pile-up probability, increased from 1032.1 ± 109.5 to 1789.5 ± 218.5 ns (photopeak position). With this amplification a full width at half maximum (FWHM) energy resolution of 14.1 ± 2.0% and a high linearity of the energy detection was obtained. A FWHM coincidence resolving time (CRT) of 313 ps was achieved by using a low timing threshold, increasing the bandwidth of the front-end circuit and using a narrow ± 1σ energy window. To approximately double the sensitivity and reduce the power consumption, the timing parameters were adjusted resulting in a FWHM CRT of 354 ps (±2σ). Significance. Based on the results obtained with the proof-of-concept detector setup, we confirm the modularity and flexibility of the all-in-one TOF-PET detector modules for the future development of application-specific high-resolution PET systems.
Evaporation behavior of liquid microdroplets in atmospheric-pressure nonequilibrium plasma
Authors: Nitta Kaishu , Muneoka Hitoshi , Shimizu Yoshiki , Kobayashi Hiromichi , Terashima Kazuo , Ito Tsuyohito 
Published: May 2023

Abstract
In recent years, atmospheric-pressure nonequilibrium plasma processing using microdroplets has attracted significant attention. To improve the controllability of this process, an understanding of the evaporation behavior of droplets in plasma is highly desirable. In this study, we examine the evaporation behavior of well-controlled inkjet droplets in atmospheric-pressure nonequilibrium argon plasma through both experiments and modeling. A comparison of the droplet evaporation model based on energy balance considering gas temperature, electron and ion collisions, and recombination reactions with experimental evaporation behavior suggests that droplet evaporation is enhanced in high-density plasma environments with electron and ion densities exceeding 1019 m−3 when compared with that in non-ionized gaseous environments at a gas temperature below 1000 K.
Sub-bandgap photon-assisted electron trapping and detrapping in AlGaN/GaN heterostructure field-effect transistors
Authors: Gunn Andrew W , Prio Makhluk Hossain , Gajula Durga , Koley Goutam 
Published: May 2023

Abstract
We have investigated photon-assisted trapping and detrapping of electrons injected from the gate under negative bias in a heterostructure field-effect transistor (HFET). The electron injection rate from the gate was found to be dramatically affected by sub-bandgap laser illumination. The trapped electrons reduced the two-dimensional electron gas (2DEG) density at the AlGaN/GaN heterointerface but could also be emitted from their trap states by sub-bandgap photons, leading to a recovery of 2DEG density. The trapping and detrapping dynamics were found to be strongly dependent on the wavelength and focal position of the laser, as well as the gate bias stress time prior to illumination of the HFET. Applying this phenomenon of trapping and detrapping assisted by sub-bandgap photons, red, green, and purple lasers were used to demonstrate photo-assisted dynamic switching operations by manipulation of trapped carriers at the surface of an AlGaN/GaN HFET. A physical model based on band diagrams, explaining the trapping and detrapping behavior of electrons, has been presented.
Effect of bubbles at the bonded interface on the performance of GeSn/Si PIN photodetector
Authors: Chai Jianfei , Ke Shaoying , Huang Yuan , Tan Chuhui , Wang Rongfei , Yang Jie , Wang Chong 
Published: May 2023

Abstract
Due to the large lattice mismatch between GeSn and Si materials, high-density threading dislocation (TD) forms when GeSn films are grown by epitaxial growth. This leads to the increase of the dark current density (DCD) of the device. The wafer-bonded technique is a promising method to prepare high-quality thin films. This has been used to produce the Si-based GeSn materials with low TDD. However, there are a lot of bubbles at the bonded interface, resulting in the deterioration of the performance of the device. The study of bubbles on the performance of the GeSn PIN photodetector (PD) has not been reported. In this paper, the effects of the bonding bubbles on the performance of the device are performed. The photocurrent, dark current, charge concentration, electric field, and 3dB-bandwidth (BW) as a function of the bubble radius and thickness are demonstrated. The effects of the bubble radius and thickness on the 3dB-BW (∼18 GHz) are insignificant when the bubble thickness and radius are set as 1 nm and 1 μm, respectively. The 3dB-BW decreases to ∼17 GHz when the bubbles are close to the sizes of the top mesa. However, the 3dB-BW drops drastically with the increase of the bubble thickness when the bubble radius reaches 7 μm. Most importantly, the 3dB-BW sharply decreases to ∼30 MHz regardless of the thickness of the bubble when the bubble radius of 14 μm is set. This may provide guidance for the application of the wafer-bonded GeSn PIN PD.
Enhanced NIR fluorescence quantum yield of graphene quantum dots using dopants
Authors: Rani Priya , Dalal Ranjeet , Srivastava Sunita 
Published: May 2023

Abstract
In the present work, several efforts have been made theoretically to achieve an excellent non-toxic fluorescent graphene quantum dot (GQD) in the near-infrared region for the application of bio-imaging and sensing. Although the QY of GQDs is a maximum of 98.5% in the visible region, it is still very low, and it is as low as 7% in NIR. Sulfur and its group elements have been used for doping because they are pretty cheap and nontoxic and hence suitable for this application. The surface-doped position is considered for studying their effect on the energy band gap, absorption and fluorescence properties. The HOMO and LUMO isosurfaces have been analyzed in order to comprehend the nature of the dominant transition taking place in absorption spectra. Additionally, the quantitative indices, transition density matrix contour maps, and charge difference density have all been examined in order to determine whether this particular transition is locally excited or involves charge transfer. Following this, the QY of each GQD has been determined by considering the fluorescence spectra. The wavelength of fluorescence of doped GQDs is found to be in the region of 800–1400 nm, i.e. in NIR, which is strongly desirable for bio-imaging and bio-sensing applications. With a fluorescence of ∼850 nm, sulfur-doped GQDs (S-GQD: C52S2H18) have the greatest QY, 26%, which is larger than the 7% achieved earlier in NIR and such a high QY in NIR is being reported for the first time.
Nanoscale spectroscopic mapping by scanning probe electron energy spectroscopy
Authors: Li Zhongfeng , Xu Chunkai , Li Zhean , Huang Wei , Chen Xiangjun 
Published: May 2023

Abstract
Scanning probe electron energy spectroscopy (SPEES) is a developing technique capable of both topographic and spectroscopic mapping of the surface. Here we report a SPEES study for Ag nanostructures on graphite with a microelectrode-shielding tip. The spatial distributions of electron energy loss spectra as well as secondary-electron emission spectra in the same region on the surface are measured. The spatial resolution is determined to be about 17 nm. This demonstrates the nanoscale spectroscopic mapping ability of the SPEES and a promising tool for investigating highly-localized object on surface and related phenomena, such as plasmonic substrates, nonlinear electron scattering, etc.
Sustained and potent analgesia with negligible side effects enabled by adaptive individualized granular stimulation in rat brainstem
Authors: Forni Matilde , Thorbergsson Palmi Thor , Gällentoft Lina , Thelin Jonas , Schouenborg Jens 
Published: May 2023

Abstract

Objectives. To clarify if an adaptive current stimulation protocol, in which current amplitude is modulated during continuous stimulation, provides better efficacy than constant current stimulation protocol with respect to analgesia caused by individualized stimulation in rat periaqueductal gray matter (PAG) /dorsal raphe nuclei (DRN). Approach. Ultrathin microelectrodes adapted for recording (n = 6) and stimulation (n = 16) were implanted in rat primary somatosensory cortex and PAG/DRN, respectively. In each animal included (n = 12), a subset of PAG/DRN microelectrodes (n = 1–3 per animal) was selected that on simultaneous stimulation blocked nociceptive withdrawal reflexes in awake unrestrained animals without noticeable side effects. Analgesic effects were subsequently assessed from both nociceptive withdrawal reflexes and intracortical pain-related responses on CO2 laser hind paw stimulation. The analgesic effects of adaptive current PAG/DRN stimulation comprising incremental increases of 5 μA/microelectrode (initial median current 30 μA/microelectrode) when effects declined were compared to the effects of constant current stimulation. Behavioral effects and brain state related changes were analyzed using quantitative movement analysis and electrocorticography (recorded on top of the dura mater), respectively. Tissue reactions and probe placement in PAG/DRN were assessed with immunohistochemistry. Main results. Powerful and sustained (4 h) analgesia was achieved with the adaptive current protocol within a rather wide area of PAG/DRN. Analgesic after-effects were seen for up to 30 min. Behavioral and brain state related side effects were minimal. Moreover, 6 weeks after implantation, there were no traces of bleedings, only small glial reactions and small but not statistically significant loss of neurons nearby indicating that the microelectrode stimulation employed is biocompatible. Significance. The results indicate that sustained and powerful analgesia with minimal side effects can be achieved by granular and individualized stimulation in PAG/DRN using an adaptive current stimulation protocol. This microelectrode technology and stimulation paradigm thus has the potential of providing a highly efficient and safe pain therapy.
Investigating the impact of the molecular charge-exchange rate on detached SOLPS-ITER simulations
Authors: Verhaegh K. , Williams A.C. , Moulton D. , Lipschultz B. , Duval B.P. , Février O. , Fil A. , Harrison J. , Osborne N. , Reimerdes H. , Theiler C. , the TCV Team  
Published: May 2023

AbstractPlasma-molecular interactions generate molecular ions which react with the plasma and contribute to detachment through molecular activated recombination (MAR), reducing the ion target flux, and molecular activated dissociation (MAD), both of which create excited atoms. Hydrogenic emission from these atoms has been detected experimentally in detached TCV, JET and MAST-U deuterium plasmas. The TCV findings, however, were in disagreement with SOLPS-ITER simulations for deuterium, indicating a molecular ion density (D2+) that was insufficient to lead to significant hydrogenic emission, which was attributed to underestimates of the molecular charge exchange rate (D2+D+→D2++D) for deuterium (obtained by rescaling the hydrogen rates by their isotope mass). In this work, we have performed new SOLPS-ITER simulations with the default rate setup and a modified rate setup where ion isotope mass rescaling was disabled. This increased theD2+content by>×100. By disabling ion isotope mass rescaling: (1) the total ion sinks are more than doubled due to the inclusion of MAR; (2) the additional MAR causes the ion target flux to roll-over during detachment; (3) the totalDαemission in the divertor increases during deep detachment by roughly a factor of four; (4) the neutral atom density in the divertor is doubled due to MAD, leading to a 50% increase in neutral pressure; (5) total hydrogenic power loss is increased by up to 60% due to MAD. These differences result in an improved agreement between the experiment and the simulations in terms of spectroscopic measurements, ion source/sink inferences and the occurrence of an ion target flux roll-over. Extrapolating simplified scalings of divertor molecular densities (TCV & MAST-U) to reactor-relevant densities suggests the underestimation of molecular charge exchange could strongly impact divertor physics (neutral atom density, ions sinks) and hydrogen emission (which has implications for detachment control) in deeply detached conditions, warranting further study.
Analysis of influencing factors of projectile velocity in low-speed sub-caliber launch
Authors: Zhang B , Peng G , Feng JC , Wang XC , Wang W , Chen CX , Gao B 
Published: May 2023

Abstract
In the ballistic performance testing field of human body protection and armor protection, aiming at the demand of sub-caliber launch of assembled ammunition with the mass range of 4 ~ 16 g and velocity range of 280 ~ 500 m/s, establish the mathematical model of interior ballistic with MATLAB, calculate the interior ballistic state, and analyze the influence law of the change of charge parameters and projectile mass with the launch velocity. The results show that the propellant does not burn completely as the small-mass projectile leaves the barrel; under the same chamber volume, the projectile velocity increases with the charge mass, and this trend gradually decrease with the increasing chamber volume; under the same charge mass, the projectile velocity decreases with the increase of chamber volume, and this trend gradually increases with the increasing charge mass; under the same projectile mass, the projectile velocity decreases with the increase of charge mass, and this trend remains basically unchanged as the projectile mass increases. The analysis and calculation results are verified by the firing test. The results show that although there are differences between the actual charge quality and the calculation results, the obtained velocity changing trend is basically consistent with the trend revealed by the calculation results. The analysis and verification results can provide guidance for understanding the influencing factors affecting the launch of sub-caliber low-speed projectile, and have positive significance for improving the ballistic performance testing ability and promoting the development of the protection industry.
Base-backstepping Continuous Time-varying Feedback Control of Automatic Magazine with Modelling Uncertainty
Authors: Lin Y B , Hou B L 
Published: May 2023

Abstract
This paper proposes a continuous time-varying feedback control based on back-stepping for automatic magazine system, in which the control gains depend on the Lyapunov function to ensure the robustness against modelling uncertainty. The Lyapunov function, which is implicit, is differentiable functions of system error variables. Integrated with backstepping control, the performance of the automation magazine system is greatly improved, while retaining the advantage of only needing to ensure the bounds of disturbances. Lyapunov analysis shows tracking errors of the system are asymptotically stable. In addition, this proposed controller is continuous and has the characteristics of simplicity and practicality, which are beneficial to practical applications. Finally, Numerical simulations are provided to verify the high performance of the controller by comparing the simulation experimental results in automation magazine system.
Structural Parameters Optimal Design of the Upper Carriage Structural of a Truck-mounted Howitzer Under Multiple Working Conditions
Authors: Mao ZZ , Xu YD , Jia ZY 
Published: May 2023

Abstract
In order to reduce the force transmitted from the upper carriage of a Truck-mounted howitzer to the lower carriage, the upper carriage is optimized for structural parameters under the premise that the position of the trunnion chamber is allowed to change. Based on the secondary development function of ABAQUS, established the parametric modeling script of the upper carriage structural, and built the ABAQUS computing environment through the integration of Simcode components of the ISIGHT platform. The position parameters of the trunnion chamber on the upper carriage were selected as the design variables, and the maximum support reaction force was minimized as the optimization objective. The multi-island genetic algorithm was used to optimize the structure parameters of the upper carriage under multiple working conditions, and the global optimal solution was obtained. The optimization results meet the rigidity and strength requirements, and the optimization effect is obvious. This optimization method can be used in the design of the upper carriage structure, reducing the force transmitted from the upper carriage of the artillery to the lower carriage, and can provide a certain optimization space for the weight reduction of the lower carriage, and has engineering application value.
Application of Fuzzy Adaptive Control in Gun Servo System
Authors: Dai P , Han C W , Kong R Y , Zhang G S , Liu M 
Published: May 2023

Abstract
Friction torque is an important parameter affecting the servo system, which will decrease with the increase of service time. With the change of friction torque, the control characteristics of the servo system will change, resulting in the servo dynamic and static performance can not meet the system requirements. On the basis of expounding the composition and working principle of gun pitching servo system, a control method of gun servo system based on fuzzy adaptive control is proposed. The problem of system performance change caused by the change of servo system parameters is solved. Through MATLAB simulation, it shows that the method can eliminate the influence of friction torque change on the system, make the system insensitive to the change of torque parameters, and meet the use requirements under various parameter conditions.
Research on Performance Improvement of Projectile Velocity Measurement Model
Authors: Li Hai , Ni Jinping , Chen Ding 
Published: May 2023

Abstract
This paper studies the existing photoelectric velocimetry model, which assumes that the trajectory is straight and the projectile velocity is uniform and constant in the test area. In the test of muzzle velocity of projectile and the experiment of miss distance of proximity fuze, the influence of air resistance and other factors on the velocity during the flight of projectile is not considered, so there is a big test error in the velocity value. In this paper, an optimized test method of velocity parameters is put forward by deeply studying the aerodynamics of projectile in flight and combining with physical mechanics. Through experiments and simulation studies, it can be proved that the speed parameter value determined by this method is closer to the true value, and the relative error is much smaller than the existing measurement methods, which has certain practical value in practice.