bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi-acquisition multi-resolution full-waveform shear wave elastography for reconstructing tissue viscoelasticity
Authors: Elmeliegy Abdelrahman M , Guddati Murthy N 
Published: November 2024

Abstract

Objective. Motivated by the diagnostic value of tissue viscosity beyond elasticity, the goal of this work is to develop robust methodologies based on shear wave elastography (SWE) to reconstruct combined elasticity and viscosity maps of soft tissues out of the measurement plane. Approach. Building on recent advancements in full-waveform inversion in reconstructing elasticity maps beyond the measurement plane, we propose to reconstruct a complete viscoelasticity map by novel combination of three ideas: (a) multiresolution imaging, where lower frequency content is used to reconstruct low resolution map, which is then utilized as a starting point for higher resolution reconstruction by including higher frequency content; (b) acquiring SWE data on multiple planes from multiple pushes, one at a time, and then simultaneously using all the data to invert for a single viscoelasticity map; (c) sequential reconstruction where combined viscoelasticity reconstruction is followed by fixing the elasticity map (and thus kinematics), and repeating the reconstruction but just for the viscosity map. Main results. We examine the proposed methodology using synthetic SWE data to reconstruct the viscoelastic properties of both homogeneous and heterogeneous tumor-like inclusions with shear modulus ranging from 3 to 20 kPa, and viscosity ranging from 1 to 3 Pa·s. Final validation is performed in silico, where the annular inclusion is reconstructed using noisy data with varying signal-to-noise ratios (SNR) of 30, 20 and 10 dB. While elasticity images are reasonably reconstructed even for poor SNR of 10 dB, viscosity imaging seem to require better SNR. Significance. This work, analogous to reconstructing 3D images from 2D measurements, offers a feasibility study for achieving 3D viscoelasticity reconstructions using conventional ultrasound scanners, potentially leading to biomarkers with greater specificity compared to currently available 2D elasticity images.
High-resolution positronium lifetime tomography by the method of moments
Authors: Huang Bangyan , Qi Jinyi 
Published: November 2024

Abstract

Objective. Positronium lifetime tomography (PLT) is an emerging modality that aims to reconstruct 3D images of positronium lifetime in humans and animals in vivo. The lifetime of ortho-positronium can be influenced by the microstructure and the concentration of bio-active molecules in tissue, providing valuable information for better understanding disease progression and treatment response. However, efficient high-resolution lifetime image reconstruction methods are currently lacking. Existing methods are either computationally intensive or have poor spatial resolution. This paper presents a fast, high-resolution lifetime image reconstruction method for PLT. Approach. The proposed method, called SIMPLE-Moment (Statistical IMage reconstruction of Positron annihilation LifetimE by Moment weighting), first reconstructs a set of moment images and then estimates the ortho-positronium lifetime image using the method of moments. The implementation of SIMPLE-Moment requires minimal modification to the conventional ordered subset expectation maximization algorithm. Main results. With reasonable assumptions, the proposed method can reconstruct an ortho-positronium lifetime image with a computational cost equivalent to three standard positron emission tomography (PET) image reconstructions. A Monte Carlo simulation study based on an existing time-of-flight PET scanner demonstrates that the ortho-positronium lifetime image reconstructed by SIMPLE-Moment is accurate and comparable to results obtained using the more computationally intensive Statistical Positronium Lifetime Image reconstruction via time-Thresholding (SPLIT) method. Significance. The proposed SIMPLE-Moment method provides an efficient approach to high-resolution reconstruction of ortho-positronium lifetime images. By reducing computational costs while enhancing spatial resolution, this method has the potential to make PLT more accessible and practical for clinical and research applications.
Feasibility study of modularized pin ridge filter implementation in proton FLASH planning for liver stereotactic ablative body radiotherapy
Authors: Ma Chaoqiong , Yang Xiaofeng , Setianegara Jufri , Wang Yinan , Gao Yuan , Yu David , Patel Pretesh , Zhou Jun 
Published: November 2024

Abstract

Objective. We previously developed a FLASH planning framework for streamlined pin-ridge-filter (pin-RF) design, demonstrating its feasibility for single-energy proton FLASH planning. In this study, we refined the pin-RF design for easy assembly using reusable modules, focusing on its application in liver stereotactic ablative body radiotherapy (SABR). Approach. This framework generates an intermediate intensity-modulated proton therapy (IMPT) plan and translates it into step widths and thicknesses of pin-RFs for a single-energy FLASH plan. Parameters like energy spacing, monitor unit limit, and spot quantity were adjusted during IMPT planning, resulting in pin-RFs assembled using predefined modules with widths from 1 to 6 mm, each with a water-equivalent-thickness of 5 mm. This approach was validated on three liver SABR cases. FLASH doses, quantified using the FLASH effectiveness model at 1–5 Gy thresholds, were compared to conventional IMPT (IMPT-CONV) doses to assess clinical benefits. Main results. The highest demand for 6 mm width modules, moderate for 2–4 mm, and minimal for 1- and 5-mm modules were shown across all cases. At lower dose thresholds, the two-beam case reduced indicators including liver V
21Gy and skin D
max by >19.4%, while the three-beam cases showed reductions

⩽

11.4%, indicating the need for higher fractional beam doses for an enhanced FLASH effect. Positive clinical benefits were seen only in the two-beam case at the 5 Gy threshold. At the 1 Gy threshold, the two-beam FLASH plan outperformed the IMPT-CONV plan, reducing dose indicators for all relevant normal tissues by up to 31.2%. In contrast, the three-beam cases showed negative clinical benefits, with skin D
max and liver V
21Gy increasing by up to 17.4% due to lower fractional beam doses and closer beam arrangements. Significance. This study evaluated the feasibility of modularizing streamlined pin-RFs in single-energy proton FLASH planning for liver SABR, offering guidance on optimal module composition and strategies to enhance FLASH planning.
Multiphysics simulation study in a microwave plasma reactor coupling a non-Maxwellian EEDF
Authors: Wang Ge , Hu Yedai , Li Xingxing , Yin Changbao , Zhu Huacheng , Yang Yang 
Published: November 2024

Abstract
The microwave plasma chemical vapor deposition (MPCVD) processes making use of microwave cavity system allows the preparation of diamond with important industrial application values. A carefully designed and optimized microwave plasma reactor can effectively improve the size and quality of MPCVD diamond. This poses a challenge to the accuracy of microwave plasma multiphysics simulation. This paper presents a simulation study of the microwave plasma reactor for MPCVD. The electric field mode type of the cavity is designed as TM012 and the electric field has its maximum intensity above the substrate. In the plasma modeling module, we first construct a global model based on the geometry of the electric field focusing region to study the electron energy distribution function (EEDF) of the plasma. The Boltzmann equation in the two-term approximation should be solved in the global model for a more accurate EEDF. However, to make the computation as simple as possible, we propose to fit the two-term approximation Boltzmann EEDF with a non-Maxwellian EEDF described by an analytic function, which is then coupled with the fluid equations for a self-consistent multiphysics simulation of the plasma space dependent model. The multiphysics modeling combines transient and stationary analyses and solves the plasma transport equations fully coupled with Helmholtz equation, fluid flow, and heat transfer. Finally, the simulation results are in great agreement with the experimental results. The morphology of the electron cloud in the reactor is consistent with simulated electron density distribution and the temperature error of the substrate is less than 12%. For plasma diagnostics, the hydrogen Balmer lines (H
α
and H
β
) based on optical emission spectroscopy are discussed. Additionally, this work can also serve as a reference for designing and optimizing other microwave plasma devices.
Electron impact excitation of allowed and forbidden transitions between fine-structure levels in Ti III
Authors: Wang Yang , Cao Qiu-Yao , Zhu Xi-Ming , Du Chun-Meng , Bartschat Klaus 
Published: November 2024

Abstract
Introduction: We present an extensive theoretical investigation of the electron impact excitation of doubly-ionized titanium (Ti III) to meet the needs of spectral analysis and plasma modeling. OBJECTIVES: The main objective of this work is to extend the currently scarce database of both structure and collision data for Ti III. METHODS: The calculation was performed in the close-coupling approximation using the B-spline R-matrix method. The multi-configuration Hartree–Fock method in combination with B-spline configuration interaction expansions and the non-orthogonal orbitals technique is employed for accurate descriptions of the target wave functions and adequate accounts of the various interactions between the target states. Relativistic effects are treated at the semi-relativistic Breit-Pauli approximation level. RESULTS: The present close-coupling expansion includes 138 fine-structure levels of Ti III belonging to the

3

d
2

,

4

s
2

,

4
s
4
p

,

3
d
4
l

(

l

=

0

−

3

),

3
d
5
l

(

l

=

0

−

3

),

3
d
6
s

, and

3
d
6
p

configurations. Comprehensive sets of radiative and electron collisional data are reported for all of the possible transitions between the 138 fine-structure levels. Thermally averaged collision strengths are determined using a Maxwellian distribution for a wide range of temperatures from

10
2

K to

10
5

K. The accuracy of the calculated radiative parameters is validated by comparing with available values from the NIST database and previous literature. CONCLUSION: Given the lack of sufficient currently available experimental and theoretical data, the electron impact excitation cross sections of the Ti III fine-structure levels presented here are systematic, extensive, and internally consistent, thus making them suitable for many modeling applications.
CMOS dual-band terahertz on-chip antenna array and detector design
Authors: Xu Leijun , Huang Lei , Ma Yujie , Bai Xue , Chen Jianfeng 
Published: November 2024

Abstract
In this paper, in response to the limitations of conventional single-pixel terahertz (THz) detectors in detecting a single frequency band and having a low imaging resolution. A dual-band high responsivity (Rv) array detector scheme is proposed. Includes dual-band high-gain on-chip antenna, matching circuit, dual-band self-mixing receiver circuit and integrated voltage amplifier. The proposed on-chip antenna uses a multi-loop nested design based on the octagonal antenna to realize the dual-band high gain characteristics. In addition, the use of ‘cross-loop’ metal modules as ground plane isolation effectively reduces the electromagnetic interference between the units in the array and ensures the stable operation of the detector array. The matching circuit realizes the maximum power transmission of THz signals between the antenna and the receiving circuit, improved detector Rv. The integrated two-stage voltage amplifier is able to effectively amplify the signal output from the receiver circuit to further increase the detector response voltage. The designed detector is fabricated using 0.18 μm CMOS process. Simulation results show that the antenna has a maximum gain of 5.23 dBi in the 0.37 THz band and 6.77 dBi in the 0.76 THz band. The detector can detect in both 0.37 and 0.76 THz bands. The experimental results demonstrate that the THz detector array, configured according to the proposed design scheme, exhibits a maximum Rv of 55 kV W−1 and a minimum noise equivalent power of 52.4 pW Hz1/2 at a single detector pixel operating within the 0.37 THz band.
A novel magnetorheological-polyethylene glycol shear thickening gel based on a lower temperature-sensitive gel matrix
Authors: Ge Maohui , Du Chengbin , Wang Hanyan , Jiang Shouyan , Fu Yankai 
Published: November 2024

Abstract
A novel polyethylene glycol shear thickening gel (PSTG) with lower temperature sensitivity is developed to prepare a magnetorheological-PSTG (MR-PSTG). An evaluation system for temperature-sensitive characteristics is proposed with indicators named the thermal relative effect constant (α) and the temperature coefficient of the relative effect (TCRE), which depict the physical properties and change rate of the relative shear thickening effect (RSTE), respectively. The mechanism of the reduction in temperature sensitivity is analyzed through Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy. Finally, the RSTE and relative MR effect (RMRE) of MR-PSTG are investigated under different mass fractions of carbonyl iron powder (CIP). At temperatures ranging from 5 °C to 65 °C, the α of STG is a maximum of 162% greater than that of PSTG. The TCRE of PSTG decreases with increasing temperature, with a minimum of 0.016 25 and a maximum of 0.070 02. The new molecular chains in PSTG form a more compact and stable cross-linked network, which leads to a decrease in the temperature sensitivity of PSTG. The maximum RSTE and RMRE values of MR-PSTG based on PSTG-400 are 12 418.18 and 31.42, which correspond to CIP mass fractions of 20% and 30%, respectively.
Reflection and transmission phenomenon of ultrasonic waves in a layered structure of functionally graded porous piezoelectric material
Authors: Vashishth Anil K , Bareja Umang 
Published: November 2024

Abstract
In this paper, the reflection and transmission characteristics of ultrasonic waves in a structure composed of a fluid half-space lying over functionally graded porous piezoelectric (FGPP) layers resting on the FGPP base are studied. Functionally graded porous piezoelectric materials (FGPPMs) provide a potential way to optimize performance in a variety of applications, including ultrasonics. They stand out for their customized electromechanical features and progressive property fluctuations. The material parameters of FGPPMs are assumed to change along the thickness direction. The transfer matrix is determined for the FGPP layers. The amplitude and energy ratios have been determined analytically. Numerical computation has been done to assess the effect of the angle of incidence, porosity, frequency, and gradation on reflected and transmitted energy ratios. In addition, the influence of selecting materials such as

BaTiO

3

,

PZT
−
5
H

, and

PZT
−
7
H

for the FGPP layers on the energy ratio curves is also demonstrated. The graphical analysis has examined the impact of the number of FGPP layers positioned above the half-space. The variation of the acoustic impedance for various porosities is also plotted. The graph indicates that the porosity in the structure may be changed to regulate the acoustic impedance. This will assist in reducing the energy loss at the ceramic medium interface and useful in underwater sonar detectors and medical ultrasonic imaging equipment, as well as non-destructive evaluation applications.
Analysis and comparison of three energy harvesting circuits for impact-type piezoelectric energy harvester
Authors: Yang Liu , Wei Tingcun , Chen Nan , Wang Yizhen , Shi Xue 
Published: November 2024

Abstract
The impacted-type piezoelectric energy harvesters (IPEHs) are widely used to harvest the energy of low-frequency impact forces from raindrops, human motion, machines, and other environmental sources. Owing to the typically low impact frequency, the output voltage between the two excitations undergoes damping. The attenuation coefficient λ, which reflects the damping rate, directly affects the performance of the energy harvesting circuit. This study analyzes and compares the variations of three energy harvesting circuits: full-bridge rectifier (FBR), parallel synchronized switch harvesting on inductor (P-SSHI), and synchronous electrical charge extraction (SECE) circuits under varying λ. First, the ideal energies of the three energy harvesting circuits during one impact event are summarized according to their maximum output power per half-cycle related to λ. Derivations of the IPEH with self-powered FBR, P-SSHI, and SECE circuits are provided, including the energy consumption and start-up voltage. Furthermore, these self-powered circuits connected with an IPEH are simulated. The optimal load resistance and capacitance of these circuits are analyzed relative to the variation of λ. The optimal load resistance of the SECE circuit varies significantly as λ increases, whereas the optimal loads of other circuits remain relatively constant. The output energies of the three self-powered circuits are analyzed as the force intensity and λ vary. The P-SSHI circuit yields the highest energy when appropriate components are selected. Under large λ or weak external forces, the output energy of the FBR circuit surpasses that of the SECE circuit. Finally, the three self-powered circuits are implemented in the IPEH. The experimental results show that the self-powered P-SSHI circuit generates the highest energy, with the figure of merit gradually increasing with the external force, which is consistent with the theoretical analysis. The guidance provided in this study is a reference for designing IPEH circuits.
Non-equilibrium thermodynamics in f(R, T) gravity and dark energy
Authors: Akbarpour Sudabeh , Sefiedgar Akram S , Rashidi Narges 
Published: November 2024

Abstract
Modifying general relativity may be a suitable approach to solve the dark energy problem. Among the various theories of modified gravity, we consider the f(R, T) gravity, in which R is the Ricci scalar and T is the trace of the energy-momentum tensor. As an intriguing property, the conservation equation does not hold in f(R, T) gravity. It means that the divergence of the energy-momentum tensor does not vanish. Using the formalism of irreversible thermodynamics of open systems in the presence of matter creation or matter annihilation, one can explore the physical interpretation of non-conservative energy-momentum tensor. Comparing the non-conservative energy-momentum tensor in f(R, T) gravity with the one in an irreversible open system, one may conclude that there may be a flow of energy from the gravitational sector to the matter sector, which may result in matter creation. In this paper, we study the f(R, T) gravity in the presence of the ordinary matter and the scalar field from the viewpoint of the irreversible thermodynamics of open systems to explore the possibility of matter creation. The matter creation rate, the creation pressure, the entropy production rate and the temperature evolution can be obtained. This possible matter creation in f(R, T) gravity can be considered as a component of energy which may play the role of dark energy in the recent accelerated expanding phase of the Universe.
The study of the impact of Bi2O3 on the x-ray shielding efficacy of the new barium-magnesium-boro-tellurite ceramic system
Authors: Kheswa B V 
Published: November 2024

Abstract
This computational study delves into the influence of Bi2O3 concentration on the x-ray shielding capabilities of (x)Bi2O3 + (55-x)B2O3 + 15TeO2 + 10MgO + 20BaO, with x ranging from 0 to 40 mol%. The investigation revealed that higher Bi2O3 content leads to increased linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), and effective atomic number (Zeff). Conversely, the half-value thickness (HVT), tenth-value thickness (TVT), and mean-free path (MFP) decrease as Bi2O3 concentration rises. Furthermore, the study noted a linear increase in LAC with Bi2O3 mol% at 16%, 3%, and 12% per mol% in the 15-30 keV, 40-80 keV, and 100-300 keV energy ranges, respectively. Thus, the (x)Bi2O3 + (55-x)B2O3 + 15TeO2 + 10MgO + 20BaO glass configuration demonstrates the promising potential for x-ray shielding, particularly effective for energies below 40 keV and above 80 keV, with efficacy increasing with higher Bi2O3 concentrations.
Generation of Terahertz radiation from a soliton cavity in a laser-plasma system
Authors: Verma Deepa , Sengupta Sudip , Sen Abhijit , Tiwari Sanat 
Published: November 2024

Abstract
Using particle-in-cell simulations, we demonstrate a novel mechanism for the generation of terahertz radiation in a laser-plasma system. The radiation originates from current oscillations trapped in a stable soliton cavity created by the laser in the under-dense plasma region. These oscillations behave like a current dipole antenna. The characteristics of the antenna can be controlled by tuning the laser-plasma parameters to achieve the desired output frequency. We discuss the optimum conditions for the physical realization of this mechanism and its potential practical applications.
Studies on the effect of SiC nanopowder concentration and discharge energy on surface roughness and recast layer in micro ED milling of Inconel 718 alloy
Authors: Boominathan Elumalai , Krishnan Giridharan , Gurijala Chakravarthi , VM Jothiprakash 
Published: November 2024

Abstract
Micro-EDM is one of the most viable processes for micromachining hard and conductive materials. However, the slow machining rate, high tool wear rate, and poor surface quality caused by the inherent nature of the material removal mechanism continue to pose significant challenges. This study explores the impact of silicon carbide (SiC) nanopowder (25 nm–35 nm) blended dielectric on micro-electro discharge milling of Inconel 718 alloy. The experiments were conducted using a multipurpose micromachining center equipped with a rotating spindle and Resistor Capacitor type micro-EDM module. Micro-channels were machined using various concentrations of SiC nanopowder (0 to 0.4 g l−1) in the dielectric fluid, under different discharge energy levels ranging from 7.2 μJ to 720 μJ. The process was controlled by a specialized dielectric circuit that used ultrasonic agitators and mechanical stirrers to ensure uniform nanopowder distribution during machining. The surface roughness, crater diameter and recast layer thickness were analysed. The results showed that adding SiC nanopowder reduced surface roughness up to 19.15% across all discharge energy ranges. This reduction was due to the nanopowder lowering the dielectric breakdown voltage, increasing the inter-electrode gap, and distributing energy more evenly, which resulted in smaller and more uniformly distributed craters. Surface roughness decreased further as the nanopowder concentration increased. Additionally, the study found that the inclusion of SiC powder reduced the thickness of the recast layer up to 55.3% at all energy levels by reducing the energy per spark and enhancing the removal of molten material. High-Resolution Scanning Electron Microscope (HRSEM) and Energy Dispersive x-ray Spectroscopy (EDS) analyses revealed that material migration onto the machined surface was minimized, and surface defects such as microcracks and voids were less prevalent at lower energy levels. Overall, SiC nanopowder improved the surface quality and reduced the white layer thickness in micro-EDM milling of Inconel 718.