bluuebunny/crossref_metadata_2025_split huggingface dataset:
Positron acceleration by terahertz wave and electron beam in plasma channel
Authors: Xu Zhangli , Shen Baifei , Si Meiyu , Huang Yongsheng 
Published: June 2023

Abstract
We present a scheme of positron acceleration by intense terahertz (THz) wave together with the driving large-charge electron beam in a plasma channel. The THz wave rapidly evolves into a transversely uniform acceleration field and a weakly focusing/defocusing lateral field in the channel. The THz wave is partially formed with the scheme of coherent transition radiation when the electron beam goes through a metal foil and partially because of the wakefield in the plasma channel. The electron beam continuously supplies energy to the THz wave. Such a field structure offers the feasibility of long-distance positron acceleration while preserving beam quality. By two-dimensional simulations, we demonstrate the acceleration of positrons from initial 1 GeV to 126.8 GeV with a charge of ∼10 pC over a distance of 1 m. The energy spread of accelerated positrons is 2.2%. This scheme can utilize the electron beam either from laser-driven or conventional accelerators, showing prospects towards high-quality and flexible THz-driven relativistic positron sources of ∼100 GeV.
Mathematical investigation of nanoparticle aggregation and heat transfer on mixed convective stagnation point flow of nanofluid over extendable vertical Riga plate
Authors: Mahmood Zafar , Khan Umar 
Published: June 2023

Abstract
The purpose of this study is to evaluate the effects that aggregation of nanoparticles has on mixed convective stagnation point flow and porous media across a permeable stretched vertical Riga plate in the occurrence of a heat source or sink for ethylene glycol-based nanofluids. It is possible to evaluate nanoparticle aggregation with modified versions of the Krieger-Dougherty and Maxwell-Bruggeman models. To obtain numerical solutions to the mathematical model of the present issue, the Runge–Kutta (RK-IV) with shooting technique in Mathematica was used. Figures in the proposed mixed convection and suction variables along a boundary surface in the stagnation point flow towards a permeable extending Riga plate identify and explain heat transfer processes and interrupted flow occurrences. By combining titania (TiO
2) nanoparticles with ethylene glycol as the base fluid, improved heat transmission is possible. The effects of different inputs on temperature and velocity profiles, skin friction coefficient, and local Nusselt number were graphically shown using tables and graphs. The heat transmission and skin friction rates both increased when the suction parameter was given larger values. Increases in both skin friction and the Nusselt number may be attributed to variations in the volume percentage of nanoparticles. Heat source parameter increased the temperature profile and reduced the Nusselt number. Aggregation models provide more accurate velocity and skin fraction profiles than homogeneous models, which is why they are more often used. The findings were confirmed by comparing the most up-to-date research with previously published results for the same situation. Results indicated that the two sets of data were consistent with one another.
Full-flux-surface effects on electrostatic turbulence in Wendelstein 7-X-like plasmas
Authors: Wilms Felix , Bañón Navarro Alejandro , Jenko Frank 
Published: June 2023

AbstractWe present the first nonlinear, gyrokinetic, surface-global simulations of a Wendelstein 7-X-like stellarator with kinetic electrons. As a first application, we investigate the interplay between Ion Temperature Gradient (ITG) and Trapped Electron Mode (TEM) driven turbulence in a Full-Flux-Surface (FFS) approach, as well as the effect of a neoclassical radial electric field, something that escapes the capabilities of flux-tube simulations. We find that even in this more complex setup, ITG turbulence is stabilised through a finite density gradient while TEM turbulence remains relatively weak. Furthermore, we show that the effect of the radial electric field itself is small in comparison with the variation of the gradients. Nevertheless, we observe that for some of the cases shown here, there is not only quantitative but also qualitative disagreement between flux-tube and FFS simulations, in contrast to earlier studies with an adiabatic electron model. These results emphasise the potential importance of retaining geometrical variations on the flux-surface when describing stellarator turbulence under realistic conditions.
FPGA Implementation of Integer Loop Delay Estimation with Low Complexity in Undersampling Digital Predistortion System
Authors: Ye Jincai , Fu Zhanming , Liu Qinghua 
Published: June 2023

Abstract
In a digital predistortion (DPD) system, accurate loop delay estimation is one of the prerequisites for precise calculation of the DPD coefficient. Multiplications of plural numbers are needed in most of the conventional loop delay estimation algorithms. Based on the Euclidean loop delay estimation (ELDE) method, this paper proposes a simplified Euclidean loop delay estimation (SELDE) method that can avoid the operation of the multiplication of plural numbers. The ELDE and SELDE method are implemented in actual undersampling systems, separately. The results of the experiments prove the feasibility and effectiveness of the methods. Compared with the ELDE method, the hardware resource consumption of SELDE is decreased, mainly reflected in the reduction of registers and look-up tables by 41.26% and 42.84%, respectively.
Research on the line spectrum denoising detection based on multi-scale feature autoencoder
Authors: Yin Yaping , Dai Weiguo , Zhang Zongtang , Shi Yanzi , Sun Shilin 
Published: June 2023

Abstract
Line spectrum detection is an important research direction in the field of underwater acoustic target detection. The relevant features of the target can be obtained by using the target line spectrum in the signal power spectrogram, but the radiated noise signal is susceptible to the influence of external noise, which degrades the quality of the target line spectrum and thus affects the complete extraction of the line spectrum. A denoising method is proposed in this paper based on deep learning network architecture and classical filter to extract the target line spectrum from the power spectrogram with strong background noise while maintaining the continuity of the line spectrum and improving the efficiency of line spectrum detection. The simulated signal power spectrogram is used to train the multi-scale feature autoencoder to remove different scale noise interference in the line spectrum part and then pass the morphological attribute filter to remove the background noise further and keep the line spectrum continuity. The experimental analysis of the measured fishing vessel noise signal and the simulated signal shows that the algorithm proposed in this paper can effectively remove the line spectrum noise interference, improve the line spectrum signal-to-noise ratio quality, and realize the effective detection of the line spectrum.
Optimal Design of Antennas based on CNN and BLS
Authors: Wang Xiaoyan , Tian Yubo 
Published: June 2023

Abstract
Surrogate can greatly reduce the computing cost of full-wave electromagnetic simulation software in antenna design, and neural networks as a kind of surrogate have become very popular in recent years, among which the Convolutional Neural Network (CNN) is a very hot topic due to its better feature extraction and generalization capability. In this paper, Broad Learning System (BLS) is introduced to address the problems that CNN may fall into with local optimization and overfitting when dealing with antenna data. It provides a learning method to increase nodes in width for regression prediction, which has good generalization ability. Specifically, in antenna design, feature extraction is first applied using the convolution and pooling of CNN. The original dataset is combined with the extracted feature data to realize data augmentation, and then the BLS is used for regression training. Compared with the traditional deep CNN, this model uses lightweight convolutional layers, which is promising in solving the problem of the network falling into local optimum or overfitting. The simulation results show that the accuracy reaches 93.91% and 92.34% respectively on the Abalone benchmark and antenna data, proving the effectiveness of the proposed model in this paper.
Downlink channel estimation of intelligent reflective surface aided MU-MIMO system
Authors: Li Qingyun , Dou Zheng , Li Zhigang , Li Xinxiang 
Published: June 2023

Abstract
Obtaining channel status information (CSI) is one of the main problems of the intelligent reflective surface (IRS) assisted communication system. This is because IRS has only a large number of passive reflective components and cannot process signals. In this paper, we aim to estimate downlink channel of IRS assisted multi-user multiple-input multiple-output (MU-MIMO) communication system. In time division duplex (TDD) mode, the downlink channel is estimated according to the uplink pilot by using channel reciprocity. We propose a parallel factor analysis based on projection subspace (PSS-PARAFAC) channel estimation scheme. In the first step, the common sparsity among multiple users is used for signal subspace projection to reduce noise energy and complexity. The second step is to convert each user signal received of base station (BS) into the PARAFAC problem. The iterative method of alternating least squares (ALS) is used to solve this problem. From the analysis of simulation results, the channel estimation performance of the proposed algorithm is better.
A Broadband Optical Fiber Coupler Based on Dual-Hollow Core Fiber
Authors: Zhang Zili , Chen Huajin , Wang Changxu , Li Yuan 
Published: June 2023

Abstract
Hollow fiber has become a research hotspot in the field of special fibers for its excellent characteristics, such as low loss, low delay, low dispersion, and low nonlinear coefficient. Due to the lack of fiber coupler matching hollow core fiber, the application development of hollow core fiber in the all-fiber integrated system is greatly hindered. Dual-core fiber is widely used in the development of fiber couplers because it can choose optical power, wavelength, and polarization state by the coupling between the two cores. For the urgent need for hollow core fiber coupler, the design and research of wideband fiber coupler based on dual-hollow core fiber are carried out in this paper. Based on the coupled mode theory, the theoretical correlation between the structural parameters and the coupling length in the dual-hollow core anti-resonant fiber was analyzed by using the COMSOL simulation software system. On this basis, a 50:50 wideband fiber coupler was designed by adjusting the structural parameters to reduce the coupling length and introducing the sleeve into the cladding pipe to reduce the loss. The bandwidth of the coupler is up to 150 nm and the transmission loss is on the order of 10−2 dB/m.
Sulfur isotopes quantify the impact of anthropogenic activities on industrial-era Arctic sulfate in a Greenland ice core
Authors: Jongebloed Ursula A , Schauer Andrew J , Hattori Shohei , Cole-Dai Jihong , Larrick Carleigh G , Salimi Sara , Edouard Shana R , Geng Lei , Alexander Becky 
Published: June 2023

Abstract
Anthropogenic sulfate aerosols are estimated to have offset 60% of greenhouse-gas-induced warming in the Arctic, a region warming four times faster than the rest of the world. However, sulfate radiative forcing estimates remain uncertain because the relative contributions from anthropogenic versus natural sources to total sulfate aerosols are unknown. Here we measure sulfur isotopes of sulfate in a Summit, Greenland ice core from 1850 to 2006 CE to quantify the contribution of anthropogenic sulfur emissions to ice core sulfate. We use a Keeling plot to determine the anthropogenic sulfur isotopic signature (δ34Santhro = +2.9 ± 0.3 ‰), and compare this result to a compilation of sulfur isotope measurements of oil and coal. Using δ34Santhro, we quantify anthropogenic sulfate concentration separated from natural sulfate. Anthropogenic sulfate concentration increases to 67 ± 7% of non-sea-salt sulfate (65.1 ± 20.2 µg kg−1) during peak anthropogenic emissions from 1960 to 1990 and decreases to 45 ± 11% of non-sea-salt sulfate (25.4 ± 12.8 µg kg−1) from 1996 to 2006. These observations provide the first long-term record of anthropogenic sulfate distinguished from natural sources (e.g. volcanoes, dimethyl sulfide), and can be used to evaluate model characterization of anthropogenic sulfate aerosol fraction and radiative forcing over the industrial era.
Structural and critical properties of Pr0.5Sr0.5MnO3 nanoparticle
Authors: Thi Viet Chinh Nguyen , Linh Dinh Chi , Thi Dung Nguyen , Thanh Tran Dang 
Published: June 2023

Abstract
In this work, a sample of Pr0.5Sr0.5MnO3 nanoparticles with an average crystalline size of <D> = 58 ± 2 nm was prepared by a combination of reactive milling method for 6 h at room temperature and heat treatment at the 1100 °C for 0.5 h. The x-ray diffraction analysis revealed the existence of a Pr0.5Sr0.5MnO3 single phase with the tetragonal structure (I4/mcm space group). Temperature and magnetic field dependences of magnetisation measurements indicated a coexistence of two magnetic phase transitions. One is the antiferromagnetic-ferromagnetic transition at T
N = 150 K. The other is the second-order ferromagnetic-paramagnetic phase transition at T
C = 273.5 K. Using the modified Arrott plots and the Kouvel-Fisher methods, the critical isotherm analysis, and the scaling relation, the magnetic order in Pr0.5Sr0.5MnO3 nanoparticle sample has been pointed out. Accordingly, the critical exponents were found to be β = 0.486, γ = 1.181, and δ = 3.249. These values are quite close to the allowable exponents of the mean field model, suggesting an existence of the long-range ferromagnetic order. A slight deviation from the mean field model has been explained by the formation of the core/shell structure in Pr0.5Sr0.5MnO3 nanoparticle.
A systematic review of cardiac in-silico clinical trials
Authors: Rodero Cristobal , Baptiste Tiffany M G , Barrows Rosie K , Keramati Hamed , Sillett Charles P , Strocchi Marina , Lamata Pablo , Niederer Steven A 
Published: June 2023

Abstract
Computational models of the heart are now being used to assess the effectiveness and feasibility of interventions through in-silico clinical trials (ISCTs). As the adoption and acceptance of ISCTs increases, best practices for reporting the methodology and analysing the results will emerge. Focusing in the area of cardiology, we aim to evaluate the types of ISCTs, their analysis methods and their reporting standards. To this end, we conducted a systematic review of cardiac ISCTs over the period of 1 January 2012–1 January 2022, following the preferred reporting items for systematic reviews and meta-analysis (PRISMA). We considered cardiac ISCTs of human patient cohorts, and excluded studies of single individuals and those in which models were used to guide a procedure without comparing against a control group. We identified 36 publications that described cardiac ISCTs, with most of the studies coming from the US and the UK. In

75
%

of the studies, a validation step was performed, although the specific type of validation varied between the studies. ANSYS FLUENT was the most commonly used software in

19
%

of ISCTs. The specific software used was not reported in

14
%

of the studies. Unlike clinical trials, we found a lack of consistent reporting of patient demographics, with

28
%

of the studies not reporting them. Uncertainty quantification was limited, with sensitivity analysis performed in only

19
%

of the studies. In

97
%

of the ISCTs, no link was provided to provide easy access to the data or models used in the study. There was no consistent naming of study types with a wide range of studies that could potentially be considered ISCTs. There is a clear need for community agreement on minimal reporting standards on patient demographics, accepted standards for ISCT cohort quality control, uncertainty quantification, and increased model and data sharing.
Recent advances in nanofiber-based flexible transparent electrodes
Authors: Zhang Houchao , Zhu Xiaoyang , Tai Yuping , Zhou Junyi , Li Hongke , Li Zhenghao , Wang Rui , Zhang Jinbao , Zhang Youchao , Ge Wensong , Zhang Fan , Sun Luanfa , Zhang Guangming , Lan Hongbo 
Published: June 2023

Abstract
Flexible and stretchable transparent electrodes are widely used in smart display, energy, wearable devices and other fields. Due to the limitations of flexibility and stretchability of indium tin oxide electrodes, alternative electrodes have appeared, such as metal films, metal nanowires, and conductive meshes. However, few of the above electrodes can simultaneously have excellent flexibility, stretchability, and optoelectronic properties. Nanofiber (NF), a continuous ultra-long one-dimensional conductive material, is considered to be one of the ideal materials for high-performance transparent electrodes with excellent properties due to its unique structure. This paper summarizes the important research progress of NF flexible transparent electrodes (FTEs) in recent years from the aspects of NF electrode materials, preparation technology and application. First, the unique advantages and limitations of various NF materials are systematically discussed. Then, we summarize the preparation technology of various advanced NF FTEs, and point out the future development trend. We also discuss the application of NFs in solar cells, supercapacitors, electric heating equipments, sensors, etc, and analyze its development potential in flexible electronic equipment, as well as problems that need to be solved. Finally, the challenges and future development trends are proposed in the wide application of NF FTEs in the field of flexible optoelectronics.
Hilbert points in Hardy spaces
Authors: Brevig O. , Ortega-Cerdà J. , Seip K. 
Published: June 2023

A Hilbert point in

H
p

(

T

d

)

H^p(\mathbb {T}^d)

, for

d
≥
1

d\geq 1

and

1
≤
p
≤
∞

1\leq p \leq \infty

, is a nontrivial function

φ
\varphi

in

H
p

(

T

d

)

H^p(\mathbb {T}^d)

such that

‖
φ

‖

H
p

(

T

d

)

≤
‖
φ
+
f

‖

H
p

(

T

d

)

\| \varphi \|_{H^p(\mathbb {T}^d)} \leq \|\varphi + f\|_{H^p(\mathbb {T}^d)}

whenever

f
f

is in

H
p

(

T

d

)

H^p(\mathbb {T}^d)

and orthogonal to

φ
\varphi

in the usual

L
2

L^2

sense. When

p
≠
2

p\neq 2

,

φ
\varphi

is a Hilbert point in

H
p

(

T

)

H^p(\mathbb {T})

if and only if

φ
\varphi

is a nonzero multiple of an inner function. An inner function on

T

d

\mathbb {T}^d

is a Hilbert point in any of the spaces

H
p

(

T

d

)

H^p(\mathbb {T}^d)

, but there are other Hilbert points as well when

d
≥
2

d\geq 2

. The case of

1
1

-homogeneous polynomials is studied in depth and, as a byproduct, a new proof is given for the sharp Khinchin inequality for Steinhaus variables in the range

2
>
p
>
∞

2>p>\infty

. Briefly, the dynamics of a certain nonlinear projection operator is treated. This operator characterizes Hilbert points as its fixed points. An example is exhibited of a function

φ
\varphi

that is a Hilbert point in

H
p

(

T

3

)

H^p(\mathbb {T}^3)

for

p
=
2
,
4

p=2, 4

, but not for any other

p
p

; this is verified rigorously for

p
>
4

p>4

but only numerically for

1
≤
p
>
4

1\leq p>4

.
Power dilation systems {𝑓(𝑧^{𝑘})}_{𝑘∈ℕ} in Dirichlet-type spaces
Authors: Dan H. , Guo K. 
Published: June 2023

Power dilation systems

{
f
(

z
k

)

}

k
∈

N

\{f(z^k)\}_{k\in \mathbb {N}}

in Dirichlet-type spaces

D

t

(
t
∈

R

)

\mathcal {D}_t\ (t\in \mathbb {R})

are treated. When

t
≠
0

t\neq 0

, it is proved that a system of functions

{
f
(

z
k

)

}

k
∈

N

\{f(z^k)\}_{k\in \mathbb {N}}

is orthogonal in

D

t

\mathcal {D}_t

only if

f
=
c

z
N

f=cz^N

for some constant

c
c

and some positive integer

N
N

. Complete characterizations are also given of unconditional bases and frames formed by power dilation systems of Dirichlet-type spaces. Finally, these results are applied to the operator theoretic case of the moment problem on Dirichlet-type spaces.
The Hybrid Technique for Autologous Gluteal Augmentation
Authors: Ghavami Ashkan , Halani Sameer H , Amirlak Bardia 
Published: June 2023

AbstractThis article accompanying these videos will describe the technique created and innovated by the senior author for gluteal augmentation with autologous fat transfer. While the principles of gluteal fat grafting originated with Pitanguy, Regnault, Gonazalez, and Spina, the nuances vary greatly from surgeon to surgeon. Although there is much controversy regarding gluteal fat grafting, the major principle of avoiding intramuscular injection is the central pillar of safe and effective augmentation today. The senior author fine-tuned his method to optimize patient outcomes over the past 14 years and demonstrated lasting, aesthetic results while maximizing patient safety with his technique. More recently, the senior surgeon has developed the Hybrid Technique, involving manual injection of fat through a syringe and a power-assisted cannula to maximize aesthetic outcomes while adhering to safety principles. This method follows the deep and moderate depth subcutaneous injection principle while respecting the muscular, neurovascular, and ligamentous anatomy of the buttock.Level of Evidence: 4
Diagnostic performance of clinical likelihood models of obstructive coronary artery disease to predict myocardial perfusion defects
Authors: Rasmussen Laust Dupont , Albertsen Line Emilie Brøgger , Nissen Louise , Ejlersen June Anita , Isaksen Christin , Murphy Theodore , Søndergaard Hanne Maare , Kirk Jane , Brix Lau , Gormsen Lars Christian , Petersen Steffen E , Bøttcher Morten , Winther Simon 
Published: June 2023

Abstract

Aims
Clinical likelihood (CL) models are designed based on a reference of coronary stenosis in patients with suspected obstructive coronary artery disease. However, a reference standard for myocardial perfusion defects (MPDs) could be more appropriate. We aimed to investigate the ability of the 2019 European Society of Cardiology pre-test probability (ESC-PTP), the risk-factor-weighted (RF-CL) model, and coronary artery calcium score-weighted (CACS-CL) model to diagnose MPDs.

Methods and results
Symptomatic stable de novo chest pain patients (n = 3374) underwent coronary computed tomography angiography and subsequent myocardial perfusion imaging by single-photon emission computed tomography, positron emission tomography, or cardiac magnetic resonance. For all modalities, MPD was defined as coronary computed tomography angiography with suspected stenosis and stress-perfusion abnormality in ≥2 segments. The ESC-PTP was calculated based on age, sex, and symptom typicality, and the RF-CL and CACS-CL additionally included a number of risk factors and CACS. In total, 219/3374 (6.5%) patients had an MPD. Both the RF-CL and the CACS-CL classified substantially more patients to low CL (&lt;5%) of obstructive coronary artery disease compared with the ESC-PTP (32.5 and 54.1 vs. 12.0%, P &lt; 0.001) with preserved low prevalences of MPD (&lt;2% for all models). Compared with the ESC-PTP [area under the receiver-operating characteristic curve (AUC) 0.74 (0.71–0.78)], the discrimination of having an MPD was higher for the CACS-CL model [AUC 0.88 (0.86–0.91), P &lt; 0.001], while it was similar for the RF-CL model [AUC 0.73 (0.70–0.76), P = 0.32].

Conclusion
Compared with basic CL models, the RF-CL and CACS-CL models improve down classification of patients to a very low-risk group with a low prevalence of MPD.