bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computationally efficient collimator-detector response compensation in high energy SPECT using 1D convolutions and rotations
Authors: Polson Lucas A , Esquinas Pedro , Kurkowska Sara , Li Chenguang , Sheikhzadeh Peyman , Abbassi Mehrshad , Farzanehfar Saeed , Mirabedian Seyyede , Uribe Carlos , Rahmim Arman 
Published: December 2024

Abstract

Objective. Modeling of the collimator-detector response (CDR) in single photon emission computed tomography (SPECT) reconstruction enables improved resolution and accuracy, and is thus important for quantitative imaging applications such as dosimetry. The implementation of CDR modeling, however, can become a computational bottleneck when there are substantial components of septal penetration and scatter in the acquired data, since a direct convolution-based approach requires large 2D kernels. This work proposes a 1D convolution and rotation-based CDR model that reduces reconstruction times but maintains consistency with models that employ 2D convolutions. To enable open-source development and use of these models in image reconstruction, we release a SPECTPSFToolbox repository for the PyTomography project on GitHub. Approach. A 1D/rotation-based CDR model was formulated and subsequently fit to Monte Carlo (MC) point source data representative of 177Lu, 131I, and 225Ac imaging. Computation times of (i) the proposed 1D/rotation-based model and (ii) a traditional model that uses 2D convolutions were compared for typical SPECT matrix sizes. Both CDR models were then used in the reconstruction of MC, physical phantom, and patient data; the models were compared by quantifying total counts in hot regions of interest (ROIs) and activity contrast between hot ROIs and background regions. Results. For typical matrix sizes in SPECT reconstruction, application of the 1D/rotation-based model provides a two-fold computational speed-up over the 2D model when running on GPU. Only small differences between the 1D/rotation-based and 2D models (order of 1%) were obtained for count and contrast quantification in select ROIs. Significance. A technique for CDR modeling in SPECT was proposed that (i) significantly speeds up reconstruction times, and (ii) yields nearly identical reconstructions to traditional 2D convolution based CDR techniques. The released toolbox will permit open-source development of similar models for different isotopes and collimators.
Proteinoid-polyaniline neuromorphic composites for audio recognition
Authors: Mougkogiannis Panagiotis , Adamatzky Andrew 
Published: December 2024

Abstract
We present an innovative neuromorphic system using a proteinoid-polyaniline (PANI) composite for recognition of audio inputs of the English alphabet. Neuromorphic devices, which draw inspiration from the neural networks of the brain, have emerged as very promising potential solutions for efficient signal processing. The proteinoid-PANI composite was synthesized through a template-free method, resulting in a unique nanostructure consisting of both nanorods and nanospheres. Principal component analysis, spectrogram analysis, and temporal spiking response analysis were among the signal processing methods used to examine the composite’s audio response to English alphabet stimuli. The system showed a moderate positive correlation between input and output signals, unique time–frequency response patterns, and convoluted spiking behaviour. In addition, the output amplitude showed less variation compared to the input, while maintaining the same temporal characteristics. Microscopic analysis provided detailed information about the morphology of the composite. The nanorods displayed an optimal aspect ratio and had diameters of around 100 nm, while the nanospheres varied in size, ranging from 200 to 500 nm in diameter. The nanostructure, morphological characteristics, and signal processing properties of the proteinoid-PANI composite demonstrate its potential for advanced applications in neuromorphic computing and signal processing, particularly in speech recognition and human–machine interaction.
Design, experiment and modeling of a damper based on magnetic gradient pinch mode MR valve
Authors: Lin Dezhao , Yang Fan , Li Ruihong , Zhang Weiqiang 
Published: December 2024

Abstract
In this study, a novel magnetorheological (MR) damper designed based on the magnetic gradient pinch mode MR (MGPMR) valve, is investigated analytically and experimentally. The prototype and experimental platform are designed and established to characterize the dynamic force–displacement/velocity properties under board ranges of excitation and current conditions with the consideration of the effect of design parameters, which mainly includes the number of the non-magnetic rings and the diameter of the flow channel. The experimental data shows that the tunable damping range is positive correlation with the number of non-magnetic rings and negative correlation with the diameter of flow channel. Therefore, an analytical model, which considers the hysteresis damping model of the MGPMR valve, ideal gas model, and the hysteresis friction of seals, is established to describes the dynamic force–displacement/velocity properties of the MGPMR damper with 4 non-magnetic rings and 7 mm diameter of the MGPMR valve. The proposed hysteresis damping model of the MGPMR valve consists of the tangential hyperbolic hysteresis model, tunable viscous damping, and fluid inertial together with the identified model parameters. The validity of the proposed model of MGPMR damper is demonstrated through a comparison between the simulation and experiment results showing good agreement of the hysteresis loops and output force-displacement/velocity characteristics under wide range of excitation and currents conditions.
Interference of longitudinal and transversal fragmentations in the Josephson tunneling dynamics of Bose–Einstein condensates
Authors: Bhowmik Anal , Alon Ofir E 
Published: December 2024

Abstract
The dynamics of bosons in Josephson junctions have drawn much attention where the bosons are initially condensed. When interacting bosons tunnel back and forth along the junction, depletion and, eventually, fragmentation develop. Here, we pose the question how do fragmented bosons tunnel in a bosonic Josephson junction? To this end, we exploit the transverse degree-of-freedom of the junction to encode initial fragmentation to the bosonic cloud. We find rich many-body dynamics, which includes the speed up of the collapse of density oscillations and slow down of the revival process, by analyzing the survival probability along the junction, fluctuations of particle positions across the junction, and the occupancy of the lowest single-particle states. It is found that a fully fragmented state significantly accelerates the revival process compared to the conventional Bose–Einstein condensate. To explain the underlying many-body mechanism, we show that the initial fragmentation in the transverse direction interferes with the development of fragmentation in time along the junction. The magnitude of this interference is quantified by the transition from a decrease of occupation to build up of occupation in the first excited single-particle state. The interference mechanism is a purely many-body effect that does not occur in the mean-field dynamics. All in all, we show that the interference of longitudinal and transversal fragmentations leads to new rules for macroscopic tunneling phenomena of interacting bosons in traps.
3D simulation of polar bear fur’s thermal insulation
Authors: Rchida Lamiaâ , Bihi Abdelilah Nait , Rattal Mourad , Bahou Younouss , Mouhsen Azeddine , Harmouchi Mohammed , Oualim El Mostafa 
Published: December 2024

Abstract
Biomimicry, emulating nature’s time-tested strategies, has emerged as a powerful tool for solving complex engineering challenges. Over millions of years of evolution, organisms have developed highly efficient systems for survival in extreme environments, offering solutions that often surpass human-made technologies. Scientists can create materials that mimic nature’s exceptional efficiency in regulating heat transfer by studying natural systems, such as polar bear’s fur or other organism’s structures adapted to harsh climates. With its specialised multi-layered structure and optical properties, the polar bear’s fur is an excellent model for managing heat retention. This study examines its insulating qualities using a comprehensive 3D simulation to understand how the structure regulates body heat. We use MATLAB to simulate radiative heat transfer between individual hair fibers while considering optical characteristics, such as transmittance, absorption, and reflectivity. The results reveal that even in freezing temperatures (−40 °C), the unique structure of polar bear hair considerably reduces radiative heat loss, keeping interior temperatures over 37 °C. Additionally, according to our simulations, multi-layer hair arrangements increase thermal efficiency by up to 16 °C, indicating conceivable uses for bio-inspired insulation materials. These results have consequences for ecological sustainability, the development of thermal insulation technology, and the design of energy-efficient materials and structures.
Reflective linear polarization converter with multimode, dual band and high efficiency
Authors: Ahmad Ijaz , Ali Wajid , Zhou Rongjiang , Jamali Sain Bux , Deng Lianwen 
Published: December 2024

Abstract
A thin, dual-band, highly efficient linear polarization converter based on a multi-mode metasurface was proposed. The high-efficiency manipulation of polarization states of electromagnetic waves in dual-band frequencies was achieved by utilizing a diagonally etched metasurface as a square joined by a ring. The metasurface transforms incident linearly polarized (LP) waves into cross-polarized LP waves at various frequencies. Numerical simulations reveal that the metasurface operates efficiently in the bands from 7.724 GHz to 8.192 GHz and 13.142 GHz to 15.95 GHz, with a polarization conversion ratio (PCR) of about 95% in both bands. To validate the theoretical analysis and simulation results, a model is fabricated and measured. The experimental results confirm that the proposed metasurface successfully achieves dual-band and dual-mode polarization conversion, showing reasonable consistency of theoretical and simulated findings. This converter can optimize the signal performance by clarifying polarized radio waves.
Ground state manipulation of atomic waveguide by a giant atom
Authors: Sun Ruijin , Wang Zhihai 
Published: December 2024

Abstract
In this paper, we study the ground state of a Rydberg atomic waveguide, which is coupled to a giant atom nonlocally via two or multiple sites. This many body system undergoes the degeneracy broken or energy level anti-crossing, depending on the parity of the size of the giant atom and the detuning between the atomic transition frequency and that of the driving field. Together with manipulation of the energy gap, we further show the interesting alternative atomic magnetization in the waveguide and the simultaneous suppression of the atomic magnetization and enhancement of atomic correlation.
Thermodynamic properties of condensates with spin-

f

atoms (

f
≥
1

) in the neighborhood of zero temperature
Authors: He Y Z , Liu Y M , Bao C G , Li Z B 
Published: December 2024

Abstract
When the Hamiltonian of a condensate containing spin-

f

bosons is dominated by attractive singlet pairing interaction with the strength − ∣G
0∣ and when the temperature T is in the neighborhood of zero, the many-body Schrödinger equation can be exactly solved. Based on the complete and exact spectra the thermodynamic properties of these systems different in particle number N and

f

have been studied. The variation of the function

∂
C

∂
x

against x is firstly studied, where C is the capacity, x ≡ lg(k
B
T/∣G
0∣), and k
B is the Boltzmann constant. It was found that the variation can be divided into four stages. In the very narrow first stage,

∂
C

∂
x

appears as a sharp peak. The second stage is broad where

∂
C

∂
x

=
0

. The third stage is also very narrow where

∂
C

∂
x

appears as a sharp anti-peak. In the fourth stage,

∂
C

∂
x

becomes zero again. All the thermodynamic functions: the internal energy, the capacity, and the entropy vary accordingly. How these functions are affected by N,

f

, and ∣G
0∣ in each stage has been clarified. The spin-thermodynamics would replace the traditional thermodynamics in the neighborhood of zero temperature, where the spin degrees of freedom play an essential role.
Probing heavy charged Higgs bosons at gamma-gamma colliders using a multivariate technique*
Authors: Ahmed Ijaz , Quddus Abdul , Muhammad Jamil , Shoaib Muhammad , Shafaq Saba 
Published: December 2024

Abstract
This study explores the production of charged Higgs particles through photon-photon collisions within the context of the Two Higgs Doublet Model, including one-loop-level scattering amplitudes of electroweak and QED radiation. The cross-section has been scanned for the plane (

) to investigate the process of

. Three particular numerical scenarios, i.e., low-

, non-alignment, and short-cascade are employed. The decay channels for charged Higgs particles are examined using

for low-

and

for non-alignment and short-cascade scenarios incorporating the new experimental and theoretical constraints along with the analysis for cross-sections. We find that, at a low energy, the cross-section is consistently higher for all scenarios. However, as

increases, it reaches a peak value at 1

TeV for all benchmark scenarios. The branching ratio of the decay channels indicates that for non-alignment, the mode of decay

takes control, and for a short cascade, the prominent decay mode remains

, whereas in the low-

scenario, the dominant decay channel is of

. In our research, we employ contemporary machine-learning methodologies to investigate the production of high-energy Higgs bosons within a 3.0 TeV

collider. We have used multivariate approaches such as Boosted Decision Trees (BDT), LikelihoodD, and Multilayer Perceptron (MLP) to show the observability of heavy-charged Higgs Bosons versus the most significant Standard Model backgrounds. The purity of the signal efficiency and background rejection are measured for each cut value.
Tactile sensitivity to softness in virtual reality can increase when visual expectation and tactile feedback contradict each other
Authors: Frediani Gabriele , Carpi Federico 
Published: December 2024

Abstract

Objective. The perception of softness plays a key role in interactions with various objects, both in the real world and in virtual/augmented reality (VR/AR) systems. The latter can be enriched with haptic feedback on virtual objects’ softness to improve immersivity and realism. In such systems, visual expectation can influence tactile sensitivity to softness, as multisensory integration attempts to create a coherent perceptual experience. Nevertheless, expectation is sometimes reported to attenuate, and other times to enhance, perception. Elucidating how the perception of softness is affected by visual expectation in VR/AR is relevant not only to the neuropsychology and neuroscience of perception, but also to practical applications, such as VR/AR-based training or rehabilitation. Approach. Here, by using novel wearable tactile displays of softness previously described by us, we investigated how the sensitivity to softness in a visuo–tactile VR platform can be influenced by expectation. Twelve subjects were engaged in comparing the softness of pairs of virtual objects, familiar or not, with tactile feedback of softness and visual expectation either conflicting or not. The objects’ Young’s moduli were initially randomly selected from a large set, spanning two orders of magnitude (0.5, 2, 20, 50 and 100 MPa), and then their difference was iteratively reduced, to reach the just noticeable difference in softness. Main results. For the intermediate modulus, a conflict between tactile feedback and visual expectation caused a statistically significant increase in sensitivity. Significance. This finding supports the theory that there can be conditions in which contradictory stimuli strengthen attention (to resolve conflicting sensory information), which in turn can reverse the sensory silencing effect that expectation may otherwise have on perception.
Air pollution modelling of accidents involving hazardous substances
Authors: Ostromsky Tzvetan , Alexiev Kiril , Parvanov Stefan 
Published: December 2024

Abstract
Air pollution modeling for accidents involving hazardous substances is a critical aspect of emergency response and environmental protection. This modeling aims to predict the dispersion and impact of toxic substances released into the atmosphere during accidents, such as industrial spills, transport accidents, chemical plant incidents or acts of terrorism. Such dangers are among the challenges which the modern society is facing and has to overcome. In this study we propose a systematic approach for organizing monitoring, collecting data from mobile sensors, creating situation development scenarios, modelling the spread of potential toxic-element pollution in dependence with the current meteorological conditions. The UNI-DEM model for simulation of the pollutants’ dispersion and transport in the air, as well as models for spread of leaking gas and liquid vapors are involved in this study. Finally, depending on the comprehensive analysis of the modeling results, an adequate response to such severe situations can be proposed. Assessment of safety, healthcare and environmental impacts should be the final result and the most socially important application of our work. The calculated pollutant concentrations can be compared with regulatory standards or health-based guidelines to assess potential health risks to exposed populations and environmental impacts on ecosystems. The importance of this information for emergency response planning, public health interventions, and environmental management strategies is beyond dispute.
Analytical Solution for Transverse Velocity of Turbulent Flow in Channel
Authors: Fedoseyev Alex 
Published: December 2024

Abstract
The analytical solution for the streamwise mean velocity of turbulent flow of incompressible fluid in a channel was presented in Fedoseyev (2023) paper. In this work, we present both the stationary and transient solutions for the transverse velocity component. The obtained transient solution is a product of a series of periodic functions in space and time, multiplied by a growing exponential function of time. This analytical solution reveals the instability and imminence of oscillations in the turbulent flow. The obtained solutions are compared with numerical simulation results and experimental data, demonstrating a close agreement or strong similarity.
Exploring SO2 air pollution in Plovdiv through multivariate adaptive regression splines: A case study
Authors: Ivanov Atanas , Gocheva-Ilieva Snezhana , Stoimenova-Minova Maya 
Published: December 2024

Abstract
This case study delves into the assessment of Sulfur dioxide (SO2) air pollution in Plovdiv by employing Multivariate Adaptive Regression Splines (MARS) to model and understand the factors influencing daily SO2 levels. By analyzing a dataset characterized by an average SO2 pollution level of 0.43ppm, this study highlights the potency of MARS in capturing the non-linear relationships and complex interactions between SO2 concentrations and measured meteorological and atmospheric time series in the form of quantitative and categorical variables. In particular, an increase in model performance is demonstrated by performing a modified Yeo-Johnson transformation on pollutant data and constructing additional predictors such as lag variables, date variable and dummies. A significant achievement of this investigation is the attainment of a coefficient of determination (R2) exceeding 0.91. This high level of accuracy highlights the efficiency of MARS as a flexible and reliable machine learning tool thus emphasizing its potential in contributing to the urban air quality management toolbox.
Preconditioned IDR solution method in scientific and industrial applications
Authors: Fedoseyev Alex 
Published: December 2024

Abstract
A review of preconditioned solver for large-scale applications in science and industry is presented. The analysis, parallelization, and optimization approach for large unstructured sparse matrices using IDR methods are considered for modern multicore microprocessors.
Performance criteria and methods have been revisited, along with consideration of parallelization involving the solver and preconditioner using the OpenMP environment. Results of the successful implementation for efficient parallelization are presented.
Mitigating Drying Shrinkage in High-Strength Concrete Using Glass and Polypropylene Fibers with Diatomaceous Earth as Cement Substitute
Authors: Zaki Hilma Nuraisyah , Hasan Muttaqin , Saidi Taufiq 
Published: December 2024

Abstract
In recent decades, the demand for high-strength concrete has surged due to its enhanced workability and durability. However, the high cement content in such concrete impacts its hardening properties, particularly causing drying shrinkage strain, which affects structural performance and durability. Adding fibers like glass and polypropylene can mitigate this drying shrinkage by improving tensile and flexural strength, ductility, and crack control. High cement content also raises environmental concerns, including increased CO2 emissions. Diatomaceous earth, an eco-friendly and cost-effective cement substitute, can address these issues. This study explores the effects of glass and polypropylene fibers on concrete drying shrinkage and the impact of diatomaceous earth. Concrete specimens (100 mm × 100 mm × 400 mm) with 0% and 10% diatomaceous earth and varying fiber contents (0%, 0.2%, 0.4%, 0.8%, 1%) were tested. Drying shrinkage data over 60 days were recorded using dial gauges. Results indicate that both types of fibers effectively reduce drying shrinkage, with glass fibers being more effective. Additionally, the usage of 10% diatomaceous earth also reduces drying shrinkage. A modified B4-Bazant model incorporating coefficients for diatomaceous earth (Kd), fiber type (Kf), and fiber volume (Kvf) was developed. Further research with different fiber proportions is recommended for more accurate modeling.
Experimental study of mechanical properties of conventional concrete and geopolymer concrete with and without white soil
Authors: Priastiwi Yulita Arni , Wibowo Hardi , Wijayaningsih Emy Shinta 
Published: December 2024

Abstract
Concrete is an important material in the construction of buildings, but the use of cement produces CO2 gas emissions, so it is not considered environmentally friendly. One of the efforts to replace cement without reducing the quality of concrete involves utilising fly ash and a certain percentage of white soil as a substitute for fly ash. This study compares the compressive strength, elastic modulus, and Poisson’s ratio of conventional and geopolymer concrete with or without white soil substitution with 150 x 300 mm cylindrical specimens. The fly ash was F-grade from the Tanjung Jati B Jepara power plant, and the white soil was from Kupang, NTT. A conventional concrete mix composition used a ratio of cement to fine aggregate to coarse aggregate of 1: 1.831 : 2.434 with a cement water factor of 0.5. The geopolymer concrete maintains the same proportions, substituting cement with fly ash or white soil and incorporating an alkali activator composed of NaOH (12M) and Na2SiO3 Be52 in a 1:2.5 ratio. The concrete treatment is dry curing (room temperature). The results showed that conventional concrete has a higher compressive strength and elastic modulus but a lower Poisson’s ratio compared to geopolymer concrete.