bluuebunny/crossref_metadata_2025 huggingface dataset:
7.86 kV GaN-on-GaN PN power diode with BaTiO3 for electrical field management
Authors: Xu Yibo , Vangipuram Vijay Gopal Thirupakuzi , Talesara Vishank , Cheng Junao , Zhang Yuxuan , Hashimoto Tadao , Letts Edward , Key Daryl , Zhao Hongping , Lu Wu
Published: October 2023

Devices based on gallium nitride (GaN) have great potential for high power switching applications due to the high breakdown field and high electron mobility. In this work, we present a vertical GaN-on-GaN PN power diode using high dielectric constant material, BaTiO3, for electrical field management and high breakdown voltages, in together with an optimized guard-ring and field plate design. Numerical simulation shows that with high-k dielectrics implemented, the peak electrical field at the PN interface is mitigated from 3.5 to 3.1 MV/cm under a reverse bias of −9.05 kV. The device design with BaTiO3 shows a breakdown voltage of 9.65 kV or about 600 V improvement. The fabricated diodes with a 57 μm thick drift layer demonstrate a breakdown voltage of 7.86 kV on a bulk GaN substrate. The device has an on-resistance of 2.8 mΩ cm2 and a Baliga figure of merit of 22 GW/cm2.
Free electron laser saturation: Exact solutions and logistic equation
Authors: Curcio A. , Dattoli G. , Di Palma E. , Pagnutti S.
Published: October 2023

Models attempting an analytical description of free-electron laser (FEL) devices have been proposed in the past. They provided interesting results, leading either to a deeper understanding of the FEL dynamics and to semi-analytical formulae, useful for the preliminary design of self amplified spontaneous emission and oscillator FELs. Most of these models work well until the level of mild saturation. In this paper, we comment on the so-called logistic model and a more recent analysis describing the FEL evolution in terms of Jacobi elliptic functions. Both models are shown to be suited to describe the evolution from the low signal to the onset of saturation. We attempt therefore an extension of these theoretical formulations using a delayed logistic model, capable of including characteristic features like the post saturation power oscillations.
Realizing tunneling electroresistance effect in the Au/h-BN/In2Se3/Au vertical ferroelectric tunnel junction
Authors: Yang Shuli , Kang Lili , Zheng Xiaohong , Jiang Peng , Zhao Gaofeng
Published: October 2023

Two-dimensional (2D) ferroelectric tunnel junctions (FTJs) have great potential in the design of non-volatile memory devices due to the tunneling electroresistance (TER) effect and the fact that it is not constrained by critical thickness. Incorporation of 2D ferroelectric materials in realistic FTJs inevitably involves the contacts to the traditional three-dimensional (3D) metals. However, how to design the FTJs by combining the 2D ferroelectric materials with the 3D metals still needs to be studied. In this work, we design a vertical 3D FTJ by adopting the 3D metal Au as the left and right electrodes and the 2D ferroelectric material In2Se3 together with h-BN as the central scattering region. By density functional theory combined with the non-equilibrium Green’s function (NEGF) method, we demonstrate that the h-BN intercalation with a large bandgap plays the role of good “insulator,” which breaks the symmetry of the left and right electrodes. As a result, we obtain the TER ratio of about 170%, and it can be further improved to about 1200% if two layers of In2Se3 (2L-In2Se3) are adopted as the tunneling barrier layer. Our results provide another way for the design and application of ferroelectric memory devices based on 2D ferroelectric materials.
Symmetric and asymmetric Fano resonances in a broken axial symmetry metasurface of split ring resonators
Authors: Urbonis D. , Ragulis P. , Šlekas G. , Kamarauskas A. , Seliuta D. , Kancleris Ž.
Published: October 2023

In the paper, a metasurface is investigated, the unit cell of which consists of two resonators. We show that the breaking of the axial symmetry of the unit cell in such a structure leads to the appearance of two Fano resonances instead of one that is characteristic of the symmetric unit cell. The two resonances are different, one of which is symmetric and the other is asymmetric. This is confirmed by calculating the phases of currents in the adjacent resonators. Modeling results are confirmed by experimental investigation of the metasurface spectrum in a microwave frequency range showing two resonances measured experimentally. A detailed study of the currents flowing in the adjacent resonators of the unit cell demonstrates that currents at the Fano resonance dips flow either in phase or in antiphase with respect to the external electric field, whereas in peaks this difference is π/2. This confirms the interference nature of the Fano effect.
A coupled hybrid smoothed radial point interpolation method for computing underwater acoustic scattering
Authors: Wu Shao-wei , Xiang Yang
Published: October 2023

The discrete model in the standard finite element method (FEM) always exhibits stiffer behavior than the actual continuous model. This leads to an unavoidable dispersion error that increases rapidly with the wave number. To overcome this issue in underwater acoustic scattering problems, a coupled hybrid smoothed radial point interpolation method (CHSRPIM) is proposed to reduce the dispersion error. In CHSRPIM, the modified Dirichlet-to-Neumann boundary condition is imposed on an artificial boundary to ensure that the acoustic wave correctly travels outward, and a hybrid acoustic stiffness is created using the local gradient smoothing operation to soften the stiffness. To obtain a very close-to-actual stiffness of the original model, a cell-based radial point interpolation method with three real and four virtual nodes is devised to create the acoustic shape function. The major benefit of the CHSRPIM is that, for a given mesh, the dispersion error is effectively reduced compared with that of the FEM without increasing the degrees of freedom. The performance of the proposed method is numerically evaluated. Numerical experiments are conducted to investigate the properties of the proposed method. The simulation results indicate that the CHSRPIM possesses superior computational performance and can significantly improve accuracy; therefore, it has good potential for resolving practical acoustic scattering problems in engineering.
A machine learning study to predict wind-driven water runback characteristics
Authors: Wang Jincheng , Hu Haiyang , He Ping , Hu Hui
Published: October 2023

The unsteady runback behavior of wind-driven runback water film (WDRWF) flows over aircraft surfaces has a significant impact on the aircraft icing process, one of the most significant aviation hazards in cold weather. The limited understanding of the complex multiphase interactions between freestream airflow, water film motion, and solid airframe surface makes conventional theoretical/numerical methods unable to precisely simulate WDRWF flow. Machine learning-based techniques can accurately capture complex physics using data, making it an attractive alternative to conventional methods. In this study, machine learning methods are used to predict the evolution of the front contact point (FCP) of WDRWF flow and film thickness distribution (FTD) of WDRWF flow. For FCP prediction, the performance of the Light Gradient-Boosting Machine (LightGBM) and Multi-Layer Perceptron is compared quantitatively. They perform well in capturing intermittent and smooth features, respectively. For the prediction of the spatial-temporal evolution of FTD, a computationally efficient deep neural network architecture named ConvLSTM-AutoEncoder was developed, which predicts a future FTD based on a sequence of FTDs in the past. The robustness of the ConvLSTM-AutoEncoder model to noisy input FTD is demonstrated. The generalizability of the three models is evaluated by applying the trained models to unexplored datasets. Based on the proposed techniques' generalizability, robustness, and computational efficiency, machine learning-based methods are demonstrated to be powerful tools in predicting the complex unsteady characteristics of the multiphase WDRWF flows.
Understanding under-liquid drop spreading using dynamic contact angle modeling
Authors: Debnath Debarshi , Misra Sirshendu , Kumar Parmod , Mitra Sushanta
Published: October 2023

We present numerical modeling and experimental data to investigate droplet spreading dynamics on a substrate submerged in another liquid. Dynamic contact angle equations are formulated and used to simulate the spreading of different oil drops in the presence of water. Drop spreading in the presence of water starts with a viscosity-dominated regime where a scaling law of r∼t is observed. For low viscosity drops, an intermediate inertial regime with scaling r∼t12 is observed after the viscous regime. For high viscosity drops, such an intermediate regime diminishes. At later stages near equilibrium, the spreading dynamics follow Tanner's law for all drops.
Visualization of resistance distribution and microstructure in locally degraded multilayered ceramic capacitor
Authors: Izawa K. , Utsunomiya M. , Inayama S. , Matsubara K. , Yasukawa K.
Published: October 2023

This study characterizes low-resistance regions in a locally degraded multilayered ceramic capacitor (MLCC) using scanning spreading resistivity microscopy, scanning electron microscopy, and transmission electron microscopy. The MLCC consists of a core–shell structure that degrades before electrical breakdown in highly accelerated lifetime tests. Areas of local insulation degradation in the MLCC are revealed by Dy-containing solid solution grains. The characteristic grains within the low-resistance region show the resistance distribution. Degraded grains around the anode, which are assumed to strongly reflect the front-line insulation degradation, suggest that the shell and grain boundaries strongly repress insulation degradation. These results show that improved material uniformity and microstructure design are vital for achieving highly reliable MLCCs.
Ultrafast laser-induced precession dynamics in perpendicular artificial ferrimagnetic [D022-Mn3Ga/Co2MnSi]5 superlattices
Authors: Qin Hongrui , Xie Donghang , Zhao Xupeng , Han Rongkun , Sun Hongli , Ma Meiyang , Xie Zhicheng , Wei Dahai , Ruan Xuezhong , Xu Yongbing , Zhao Jianhua
Published: October 2023

Artificial ferrimagnetic [D022-Mn3Ga/Co2MnSi]N superlattices ([Mn3Ga/CMS]N SLs) combining perpendicular magnetic anisotropy as well as exceptional thermal and magnetic stability hold promises in functional spintronic devices. However, the relevant precession dynamics are still lacking. Here, we report on the magnetic dynamic properties in [Mn3Ga/CMS]5 SLs investigated by the time-resolved magneto-optical Kerr effect (TRMOKE) measurements. The magnetization precession process and magnetic damping constant (α0) of [Mn3Ga/CMS]5 SLs rely heavily on the thickness of Mn3Ga layer (tMn3Ga). In addition, α0 is found to be higher with increasing tMn3Ga, but is not simply scaled by the uniaxial magnetic anisotropy (Ku), which can be ascribed to the contribution of spin–orbit interaction combined with the additional contributions, like spin-pumping. Furthermore, a large Ku value of 1.33 Merg/cm3 and a low α0 of 0.022 have been simultaneously obtained in [Mn3Ga/CMS]5 SL with tMn3Ga = 1.5 nm. This study contributes to the design of high-performance spintronic devices based on [Mn3Ga/CMS]N SLs.
Molecular surface programming of rectifying junctions between InAs colloidal quantum dot solids
Authors: Vafaie Maral , Morteza Najarian Amin , Xu Jian , Richter Lee J. , Li Ruipeng , Zhang Yangning , Imran Muhammad , Xia Pan , Ban Hyeong Woo , Levina Larissa , Singh Ajay , Meitzner Jet , Pattantyus-Abraham Andras G. , García de Arquer F. Pelayo , Sargent Edward H.
Published: October 2023

Heavy-metal-free III–V colloidal quantum dots (CQDs) show promise in optoelectronics: Recent advancements in the synthesis of large-diameter indium arsenide (InAs) CQDs provide access to short-wave infrared (IR) wavelengths for three-dimensional ranging and imaging. In early studies, however, we were unable to achieve a rectifying photodiode using CQDs and molybdenum oxide/polymer hole transport layers, as the shallow valence bandedge (5.0 eV) was misaligned with the ionization potentials of the widely used transport layers. This occurred when increasing CQD diameter to decrease the bandgap below 1.1 eV. Here, we develop a rectifying junction among InAs CQD layers, where we use molecular surface modifiers to tune the energy levels of InAs CQDs electrostatically. Previously developed bifunctional dithiol ligands, established for II-VI and IV-VI CQDs, exhibit slow reaction kinetics with III-V surfaces, causing the exchange to fail. We study carboxylate and thiolate binding groups, united with electron-donating free end groups, that shift upward the valence bandedge of InAs CQDs, producing valence band energies as shallow as 4.8 eV. Photophysical studies combined with density functional theory show that carboxylate-based passivants participate in strong bidentate bridging with both In and As on the CQD surface. The tuned CQD layer incorporated into a photodiode structure achieves improved performance with EQE (external quantum efficiency) of 35% (>1 μm) and dark current density < 400 nA cm
−2
, a >25% increase in EQE and >90% reduced dark current density compared to the reference device. This work represents an advance over previous III-V CQD short-wavelength IR photodetectors (EQE < 5%, dark current > 10,000 nA cm
−2
).
Elites, centers and “forces collectives”
Authors: Colistra Stefano , Ronza Rocco Walter
Published: October 2023

The concept of standard language has become highly controversial after the rise of the postmodernist paradigm.
This article traces the roots of the concept in the studies of a group of European linguists who inquired into the spread of
“common languages” and related it to the processes of modernization and the role of social elites and urban centers during the
1920s. It then reviews the central role it played in the studies on nationalism and nation-building after 1945 and discusses how
the focus on structural, macro-historical processes as determinants of the emergence of standard languages came to be abandoned in
classical and postmodernist approaches to language standardization. Finally, it suggests that Antonio Gramsci’s insights on the
“language question” in Italy should be read on the background of the early research on common languages and suggests that a
reconsideration of macro-historical approaches could contribute to the understanding of the spread of Global English.
Long-lag repetition priming in natural text reading
Authors: Coskun Melda , Kuperman Victor , Rueckl Jay
Published: October 2023

Most of the empirical evidence that lays the ground for research on recognition of printed morphologically complex
words comes from experimental paradigms employing morphological priming, e.g., exposure to morphologically related forms.
Furthermore, most of these paradigms rely on context-less presentation of isolated words. We examined whether well-established
morphological priming effects (i.e., faster recognition of a word preceded by a morphologically related word) are observable under
more natural conditions of fluent text reading. Using the GECO database of eye-movements recorded during the reading of a novel,
we examined the long-lag morphological and identity priming in one’s first language (L1, English and Dutch) or second language
(L2, English). While the effects of identity priming were ubiquitous, no evidence of morphological priming was observed in the L1
or L2 eye-movement record. We discuss implications of these findings for ecological validity and generalizability of select
current theories of morphological processing.
Cholesterol-dependent homeostatic regulation of very long chain sphingolipid synthesis
Authors: Kim Yeongho , Mavodza Grace , Senkal Can E. , Burd Christopher G.
Published: October 2023

Sphingomyelin plays a key role in cellular cholesterol homeostasis by binding to and sequestering cholesterol in the plasma membrane. We discovered that synthesis of very long chain (VLC) sphingomyelins is inversely regulated by cellular cholesterol levels; acute cholesterol depletion elicited a rapid induction of VLC-sphingolipid synthesis, increased trafficking to the Golgi apparatus and plasma membrane, while cholesterol loading reduced VLC-sphingolipid synthesis. This sphingolipid–cholesterol metabolic axis is distinct from the sterol responsive element binding protein pathway as it requires ceramide synthase 2 (CerS2) activity, epidermal growth factor receptor signaling, and was unaffected by inhibition of protein translation. Depletion of VLC-ceramides reduced plasma membrane cholesterol content, reduced plasma membrane lipid packing, and unexpectedly resulted in the accumulation of cholesterol in the cytoplasmic leaflet of the lysosome membrane. This study establishes the existence of a cholesterol–sphingolipid regulatory axis that maintains plasma membrane lipid homeostasis via regulation of sphingomyelin synthesis and trafficking.
Unpolarized QED parton distribution functions in NLO
Authors: Arbuzov A B , Voznaya U E
Published: October 2023

Perturbative solutions for unpolarized QED parton distribution and fragmentation functions are presented explicitly in the next-to-leading logarithmic approximation. The scheme of iterative solution of QED evolution equations is described in detail. Terms up to


(

α

3

L

2

)

are calculated analytically, where

L
=
ln
(

μ

F

2

/

m

e

2

)

is the large logarithm which depends on the factorization energy scale μ

F
≫ m

e
. The results are process independent and relevant for future high-precision experiments.
Fiber denseness of intermediate β-shifts of finite type
Authors: Sun Yun , Li Bing , Ding Yiming
Published: October 2023

We focus on

T

β
,
α

(
x
)
=
β
x
+
α

(

m
o
d

1),

x
∈
[
0
,
1
]

and

(
β
,
α
)
∈
Δ
:=
{
(
β
,
α
)
∈

R

2

:
β
∈
(
1
,
2
)

and

0
<
α
<
2
−
β
}

. The

T

β
,
α

±

-expansions

τ

β
,
α

±

(
x
)

of critical point

c

β
,
α

=

1
−
α

β

are called kneading invariants, denoted as

(

k

+

,

k

−

)

. Let

Δ
(

k

+

)
:=
{
(
β
,
α
)
∈
Δ
:

τ

β
,
α

+

(

c

β
,
α

)
=

k

+

}

with

k

+

being periodic, we state that

Δ
(

k

+

)

is a smooth curve which can be regarded as a fiber. By combinatorial method, we extend the results of Parry (1960 Acta Math. Acad. Sci. Hung.
11 401–16) and show that, the set of

(
β
,
α
)

with its

Ω

β
,
α

being a SFT is dense in

Δ
(

k

+

)

. Similarly for the fiber

Δ
(

k

−

)

. When considering another fiber

Δ
(
β
)
:=
{
(
β
,
α
)
∈
Δ
:
β
∈
(
1
,
2
)
 

is

 

fixed

 
}

, we demonstrate that when β is not a multinacci number, there are only countably many distinct matching intervals on

Δ
(
β
)

. Using Markov approximation, we prove that the set of

(
β
,
α
)

with

Ω

β
,
α

being a SFT is dense in each matching interval. We also propose a classification scheme for the endpoints of these matching intervals.
On the dilemma between percolation processes and fluctuating pairs as the origin of the enhanced conductivity above the superconducting transition in cuprates
Authors: Llovo I F , Mosqueira J , Vidal F
Published: October 2023

The confrontation between percolation processes and superconducting fluctuations to account for the observed enhanced in-plane electrical conductivity above but near T

c
in cuprates is revisited. This dilemma is currently an open and debated question, whose solution would contribute to the phenomenological understanding of the emergence of superconductivity in these compounds. The cuprates studied here, La1.85Sr0.15CuO4, Bi2Sr2CaCu2O

8
+
δ

, and Tl2Ba2Ca2Cu3O10, have a different number of superconducting CuO2 (ab)-layers per unit-cell length and different Josephson coupling between them, and are optimally-doped to minimize T

c
-inhomogeneities. The excellent chemical and structural quality of these optimally-doped samples also contribute to minimize the effect of extrinsic

T

c

-inhomogeneities, a crucial aspect when analyzing the possible presence of intrinsic percolative processes. Our analyses also cover the so-called high reduced-temperature region, up to the resistivity rounding onset ɛ
onset. By using the simplest form of the effective-medium theory, we show that possible emergent percolation processes alone cannot account for the measured enhanced conductivity. In contrast, these measurements can be quantitatively explained using the Gaussian–Ginzburg–Landau (GGL) approach for the effect of superconducting fluctuations in layered superconductors, extended to ɛ
onset by including a total energy cutoff, which takes into account the limits imposed by the Heisenberg uncertainty principle to the shrinkage of the superconducting wavefunction. Our present analysis confirms the adequacy of this cutoff, which was introduced heuristically, and that the effective periodicity length is controlled by the relative Josephson coupling between superconducting layers, two long standing debated aspects of the GGL approaches for multilayered superconductors. These conclusions are reinforced by analyzing, as an example, one of the recent works that allegedly discards the superconducting fluctuations scenario while supporting a percolative scenario for the enhanced conductivity above T

c
in cuprates.
Prediction of tribological performance of Cu-Gr-TiC composites based on response surface methodology and worn surface analysis
Authors: Ankit  , Kumar Vineet , Yadav Amit Kumar , Gautam Gaurav , Singh Kamalesh Kumar , Mohan Sunil
Published: October 2023

In the current study, the prediction of tribological performance of Cu-Gr-TiC composites and its correlation with surface topography has been studied. For this purpose, the Cu-Gr composites reinforced with TiC ceramic particles were prepared via the powder metallurgy route. The prepared composites microstructure, mechanical characteristics, and dry sliding wear behaviour were assessed. A pin on disc setup was taken for tribological testing where sliding velocity is 1.5 m s−1. Wear behaviour of composites was examined using a central composite design (CCD) with three levels. The wear behavior optimization was accomplished through the utilization of response surface methodology (RSM). The input parameters in RSM consisted of sliding distance, varying load, and weight percentage (wt%) of reinforcements, while the wear rate and coefficient of friction served as the two responses. An analysis of variance (ANOVA) using RSM was conducted to identify the significant parameters influencing the wear rate and coefficient of friction. A quadratic model was suggested based on best fit and a regression equation was established for predicting the tribological properties at any given input parameter. Comparative of experimental and predicted values show close tolerance. It was observed that RSM is significant tool for predicting and optimizing the tribological properties. The composite having 3.08 wt% of TiC particles was optimized for minimum wear rate & COF at 20 N load and 2000 m sliding distance.
Pressure induced electronic and optical responses of vacancy-ordered double perovskites Cs2BX6 (B = Zr, Pd, Sn; X = Cl, Br, I)
Authors: Hua Howard (Jiaqi) , Luo Xuan
Published: October 2023

Due to the toxicity and instability of lead-containing perovskites, high-performance lead-free perovskite attracts considerable attention. Lead-free vacancy-ordered double perovskites (VODP) emerge as environmentally friendly and efficient solutions as lead-containing solar cell substitutes. In this study, electronic properties of vacancy-ordered double perovskites Cs2BX6 (B = Zr, Pd, Sn; X = Cl, Br, I) under high pressure are investigated using first-principles methods. Semiconductors with bandgaps between 1.1 to 1.6 eV are considered for application. Our results show Cs2PdCl6 giving 1.60 and 1.32 eV bandgaps at 5 and 10 GPa, Cs2PdBr6 yielding 1.22 eV at ambient pressure, Cs2SnBr6 having 1.31 and 1.03 eV bandgap at 5 and 10 GPa, and Cs2ZrI6 showing 1.52 and 1.28 eV bandgap at 15 and 20 GPa. Furthermore, we considered the absorption coefficient and spectrum to ensure the materials’ optical performance. Cs2PdCl6, Cs2PdBr6, and Cs2ZrI6 display competent absorbance in the visible light range and proved these vacancy-ordered double perovskites as promising lead-free solar cell materials.
Maximizing the solar output power using hybrid (CdS/ZnSe) buffer for CIGS thin film solar cell
Authors: Shovan Saumik Dey , Ringky Samia Akhter , Islam Afia Mubassira , Islam Saiful , Rashid Mohammad Junaebur
Published: October 2023

In this work, a hybrid buffer layer (CdS & ZnSe) is placed between the absorber and the window layer in a CIGS (Copper Indium Gallium Selenide) solar cell replacing the commonly used single-layer CdS. The buffer layer plays a crucial role in interface electricity to enhance the performance of the solar cell. Although, CdS is used as a buffer layer in CIGS solar cells, the toxic nature and parasitic absorption due to the narrowband gap (2.4 eV) become issues during its application in devices. To reduce Cd concentration and ameliorate the bandgap issue, the hybrid buffer layer (CdS & ZnSe) is a perfect supplant. In this study, numerical simulation is performed on CIGS-based solar cells comprised of a hybrid buffer layer to enhance the performance by optimizing the physical parameters (thickness, carrier concentration, and defect density) of both absorber and buffer layer using SCAPS-1D software. In the process of optimizing physical parameters, the effect of the mentioned parameters is observed on the solar cell performance. Later, the impact of working temperature is shown in the solar cell performance. Finally, with all those optimized parameters, a comparison has been done between the reference and the proposed structure. The comparison asserts that the proposed structure with a conversion efficiency of 24.55% is outdistancing the reference structure as well as some relative structures from the recent study. The simulation results in this study can be a didactic one in the fabrication of high-efficiency CIGS solar cells
Active anisotropic polarization conversion meta-surface for 6G communication bandgap in the reflection mode
Authors: Jalal Abdul , Qasim Muhammad , Qureshi Ubaid Ur Rahman , Hu Bin
Published: October 2023

This paper investigates a single-layered active anisotropic meta-surface design capable of achieving high polarization conversion efficiency in the 6 G communication band gap. Additionally, the designed structure can convert the linear polarization of the incoming wave fronts to its cross-polarization and linear polarization to circular polarization in the reflection mode. The polarization conversion characteristic is achieved due to the strong anisotropic behavior of the meta-surface. Such a simple design can achieve a 90% to 100% cross-polarization conversion efficiency over a frequency region of [0.28–0.36] THz. The linear to circular polarization conversion is performed near 0.26 THz and 0.40 THz. Between these two frequencies, band linear to cross-polarization conversion is more prominent. The proposed design can be tuned from a half-wave plate (HWP) or linear polarization converter to a quarter-wave plate (QWP) or circular polarization converter using the chemical potential of graphene. The optical response of the meta-surface behaves differently from different incident angles. The proposed polarization converter can contribute to the development of active polarization device.
Bandgap tuning, mechanical and thermoelectric properties of Cs2CuScX6 (X = Cl, Br, I) halide ion substitution for optoelectronic devices using density functional theory
Authors: Maqsood Saba , Muhammad Nawaz , Murtaza G , Javed M Aamir , Mahmood Asif , Mumtaz Sohail
Published: October 2023

As a result of their exceptional optoelectronic properties, the growing need for renewable and sustainable energy has heightened interest in perovskites. Using DFT, mechanical, electronic, optical, and thermoelectric properties of double perovskites (DPs) Cs2CuScX6 (X = Cl, Br, I) were analyzed to gain a comprehensive understanding of these materials. To ensure structural and thermal stability, permissible values for the tolerance factor (tG) and energy of formation (ΔHf) have been determined. The bandgap values of Cl, Br, and I-based compositions are recorded as 1.9 eV, 1.80 eV, and 1.70 eV, respectively. According to their bandgap, Cs2CuScBr6 and Cs2CuScI6 DPs determine the suitability of the materials for use in ideal photovoltaic devices. Further, optical properties are investigated in the energy range 0–10 eV, indicating visible and ultraviolet absorption. The investigated compound Cs2CuScI6 exhibited the highest visible spectrum absorption, making it an ideal candidate for solar cell applications. Moreover, the BoltzTrap code have been used for thermoelectric behaviour for temperature shows that all double perovskites have high Seebeck coefficients and low thermal conductivities.
Gyrokinetic analysis of turbulent transport by electromagnetic turbulence in finite β plasmas with weak magnetic shear on HL-2A
Authors: Xu J.Q. , Chen W. , Peng X.D. , Hao G.Z. , Li J.Q. , Qu H.P. , Shi P.W. , He X.X. , Jiang M. , Li Y.G. ,   the HL-2A Team
Published: October 2023

Turbulent transport and zonal flow (ZF) dynamics in the mixed kinetic ballooning mode (KBM) and ion temperature gradient (ITG) mode dominated turbulence states are analyzed by gyrokinetic simulations based on the experimental observations of KBMs in the HL-2A Internal Transport Barrier (ITB) plasmas with weak magnetic shear configuration. Results have shown that KBMs and ITGs are the main candidates for turbulent transport and the inclusion of fast ions (FIs) can destabilize both instabilities, which is resulted by the decrease of ballooning parameter αMHD
hence reduced Shafranov shift stabilization due to the negative FI density gradient, making them more unstable according to the ŝ-αMHD
diagram. In addition, the ITGs are suppressed by both dilution and finite-β stabilization effects caused by FIs. Nonlinear simulations excluding the effects of FIs indicate that the transport is minimum at

β
e

=

β
e

exp

as the turbulence predominated by ITGs is strongly suppressed by the nonlinear electromagnetic (EM) stabilization and enhancement of ZFs. However, the transport is further increased with β
e although the ZFs become stronger due to the transition from ITG to KBM dominated turbulence state. The presence of FIs can modify the relation between ZF shearing rate and β
e. The transport level is insensitive to β
e when

β

e

⩽

β

e

exp

but increases significantly because of the KBM destabilization. Meanwhile, the ZF amplitude reaches maximum at

β

e

=

β

e

exp

whereas it suffers an erosion at higher values, implying that the plasma might be a self-organized critical state owning to the interactions among ZFs, KBMs and FI effects hence setting the plasma β around β
exp. The results have also provided a possible explanation that the destabilization of EM turbulence is responsible for the ion heat transport stiffness under weak magnetic shear configurations in the off-axis neutral beam injection heated ITB plasmas on HL-2A.
Numerical simulation of the effect of elastic deformation on the fairing separation process
Authors: Wang Hao , Hong Junwu , Meng Dehong , Li Wei , Yue Hao
Published: October 2023

In view of the potential impact of structural deformation on the separation safety of elastic fairing at low altitude and high speed, the aerodynamic/deformation/motion coupling analysis method is established. The numerical simulation of the separation process of the fairing considering elastic deformation after disengaging is carried out. The motion characteristics and structural response characteristics of the elastic fairing in the separation process are obtained. Moreover, the impact of elastic deformation on the attitude and trajectory of the fairing is studied. The results indicate that the elastic deformation has an impact on the attitude and trajectory of the fairing after hinge decoupling. However, for the calculation conditions in this paper, elastic deformation has no subversive effect on the separation safety.
Numerical Investigation on the influence of meteorological conditions on wind turbine icing
Authors: Zhang Lu , Li Weibin , Tong Ying , Cui Xingda , Ma Shuai
Published: October 2023

Keeping the blade structure and shape in the design condition is the premise and guarantee for efficient operation of wing turbine, but wet and cold climate will lead to icing blade, then the blade shapes were changed and the output power of the wind turbine is reduced. A numerical frame for wind turbine icing was developed in present work, which consists of a numerical method for impingement of water droplets based on the multiple frames of reference and Euler method and a 3D heat and mass transferring method for wind turbine icing, then the effects of several meteorological parameters, including the temperature, Liquid Water Content (LWC), Mean Volume Diameter (MVD) and the inflow velocity, on ice shape of the blade were investigated in the numerical frame. The present method can provide supports for prediction of icing process and aerodynamic characteristic after icing of wind turbine blades.
Influence of hydrodynamic retarder blade angle on vortex structure
Authors: Wang Yuze , Wei Wei , An Yuanyuan , Tao Tianlang , Yan Qingdong
Published: October 2023

The internal flow of the hydrodynamic retarder cavity is a complex three-dimensional turbulent flow, and the evolution of vortices in its internal two-phase flow field is closely related to the generation of braking torque and the dissipation of kinetic energy. In this study, a periodic flow channel model is used to investigate the influence of different blade angles on vortex structure characteristics. The vortex structure identification method with Q criterion is employed to compare and analyze the distribution and development of the vortex structure. Particle image velocimetry (PIV) tests are conducted to observe the evolution of the vortex structure inside the retarder and validate the simulation analysis. Results show that the increase of the vortex structure scale, intensity, and transformation speed caused by the increase of the blade angle, which affects the energy dissipation and transfer of the flow field and explains the reason for the change of the braking torque. This provides a theoretical basis for the study of the braking performance mechanism and design optimization of the hydrodynamic retarder.
Numerical analysis of influencing factors on wave load for an amphibious aircraft
Authors: Gao Xianjiao , Sang Tengjiao
Published: October 2023

Numerical method of wave load for an amphibious aircraft is carried out in this paper, and its effectiveness is verified by comparing with towing tank model test. It shows that at the same wavelength and speed, the aircraft’s wave load is positively correlated with the change of wave height, but with the increase of wavelength, the difference shows a gradually decrease. And wave load is positively correlated with the speed, the greater the speed, the greater the wave load is. The wave load decreases with the increase of the wavelength. The peak load generally occurs in the short wave state of 1.2 times the length of the fuselage. With the increase of the wavelength, the aircraft load gradually decreases.
Effect of normal magnetic field on the exact coherent state of channel flow at large Reynolds number
Authors: Shi Xiaomeng , Li Shunzhi , Li Sen , Wang Lebing , Dong Shuai
Published: October 2023

Laminar-turbulent subcritical transition has been always a hot issue in fluid mechanics. Exact coherent states are important for predicting the path of transition and understanding the cycle of turbulent self-sustaining process. One of the most common methods of investigating subcritical transition is dynamical system method and many different forms of invariant solutions have been obtained in many shear flows. In order to study the effect of magnetic field on the exact coherent state of channel flow at large Reynolds number, the direct numerical simulation combined with bisection method is used to calculate the exact coherent state-periodic orbit solution with different magnetic field strength at Re ⩾ 9000, and the structure and morphology in the flow field are compared. The results show that the magnetic field strength does not change the structure and shape of the solution and the scaling law between the transition threshold and Reynolds number does not change significantly, which shows obviously self-similarity. As the magnetic field strength increases, the period of the exact coherent state decreases and the perturbation energy in each direction exhibits periodical oscillation changes. In addition the shape of the amplitude curve also changes due to the magnetic field effect. The above results show that the magnetic field has a certain inhibition effect on the disturbance at large Reynolds number, and the flow field remains relatively stable.
Advances in Fluid Mechanics: Computing and Mathematical Models, Turbulence, Fluid Theory Applications
Authors: Wei Jiajun , Ouyang Chunfa , Shan Xiaoqian , Gao Qun , Zheng Kangsheng , Luo Wei
Published: October 2023

This paper reviews the application of computing and their mathematical principles in fluid mechanics, turbulence, and fluid mechanics. Specifically, it includes the application of computer software in fluid mechanics, the application of mathematical principles in fluid mechanics, the mathematical model in turbulence, the specific application of turbulence model, the application of fluid mechanics in engineering, and the application of fluid mechanics in simulation technology. The comparison and analysis of the similarities and differences in various applications are made to provide theoretical guidance for the researchers engaged in the research of fluid mechanics.
Aerodynamic characteristics simulation of helicopter rotor in hover using HeliX software
Authors: Cui Xingda , Sun Junfeng , Mou Bin , Ma Shuai , Zhang Lu , Xiao Zhongyun
Published: October 2023

In order to predict hover performance of a new helicopter rotor, the aerodynamic performance and flow field of the rotor in hover is calculated by using HeliX software. The comparison between numerical results and wind tunnel test data of S-76 rotor as a validation case of CFD method demonstrate that HeliX software has the capability to consistently and reliably predict performance parameters for a helicopter rotor. The numerical results of the new rotor in hover suggest that the maximum hover efficiency of the new rotor is about 73% with collective pitch angle of 9.2°, while the shock induced separation and the reattachment phenomenon begin to appear on the upper surface near the blade tip. As the increase of collective pitch angle from 9.2° to 11.2°, hover efficiency decreases significantly due to the serious flow separation near the blade tip. The research in this paper can provide reference and guidance for aerodynamic optimization design of helicopter rotor.
Numerical Simulation of the Influence of Ski-jump Deck on the Take-Off Zone Flow Field Based on CFD
Authors: Tao Sirui
Published: October 2023

Ski-jump take-off is a standard procedure for carrier-based aircrafts, and it is one of the key technologies for the generation of the combat effectiveness of the system. A 3D model carrier with a ski-jump deck is conceptually designed. The airflow field over the carrier is numerically simulated based on CFD. The longitudinal airstream line and velocity distribution, the velocity distributions in normal-wash area, tangential-wash area are derived and the influence of the ski-jump deck on the take-off zone is analyzed. The numerical simulation shows that the body-shedding vortex on both sides of the bow affects the engine intake at Take-off Point 1 and 2 and 3.
Responses of wildfire-induced global black carbon pollution and radiative forcing to climate change
Authors: Liu Xinrui , Ma Jianmin , Zhang Xiaodong , Chen Kaijie , Jian Xiaohu , Tao Shu , Liu Junfeng , Gao Hong , Huang Tao , Zhao Yuan
Published: October 2023

The impacts of climate change on wildfires have been studied extensively. Along with declining emissions from fossil fuel combustion due to anthropogenic emission control, black carbon (BC) released from wildfires is expected to contribute a more significant portion to its atmospheric burden. However, from a global perspective, little is known about the BC burden and radiative forcing caused by wildfires. Here, we report the results from the long-term wildfire-induced BC concentration and direct radiative forcing (DRF) from 1981 to 2010 globally simulated by an Earth System Model using an updated wildfire BC emission inventory. We show that wildfire-induced BC concentration and DRF varied significantly spatially and temporarily, with the highest in sub-Saharan Africa, attributable to its highest level of wildfire BC emission worldwide. The temporal trends of near-surface air temperature, precipitation, and evapotranspiration and their association with wildfire-induced BC concentration are explored using the multidimensional ensemble empirical mode decomposition. A statistically significant relation between changes in climate parameters and wildfire-induced BC concentration was found for 53% of the land grid cells, explaining on average 33% of the concentration variations. The result suggests that the wildfire-induced BC DRF, with an increasing trend, would be an important contributor to climate change, especially in sub-Saharan Africa. Occurrences of wildfires in the Amazon Basin respond most strongly to climate change and play an increasingly important role in changing the global climate.
Tristochastic operations and products of quantum states
Authors: Bistroń Rafał , Śmiałek Wojciech , Życzkowski Karol
Published: October 2023

The notion of convolution of two probability vectors, corresponding to a coincidence experiment can be extended to a family of binary operations determined by (tri)stochastic tensors, to describe Markov chains of a higher order. The problem of associativity, commutativity, and the existence of neutral elements and inverses for such operations acting on classical states is analyzed. For a more general setup of multi-stochastic tensors, we present the characterization of their probability eigenvectors. Similar results are obtained for the quantum case: we analyze tristochastic channels, which induce binary operations defined in the space of quantum states. Studying coherifications of tristochastic tensors we propose a quantum analogue of the convolution of probability vectors defined for two arbitrary density matrices of the same size. Possible applications of this notion to construct schemes of error mitigation or building blocks in quantum convolutional neural networks are discussed.
Overview of the Decarbonization Options for the Electricity Sector: Opportunities and Challenges
Authors: Triani M.
Published: October 2023

The energy demand has grown alongside increasing population growth globally. Unfortunately, the utilization of fossil fuels, especially coal, has dominated the energy sectors, including power generation. Fossil fuels have no place in the sustainability future due to the limitation of these resources and the potential environmental impacts that may arise. Therefore, the decarbonization of the electricity sector has recently become the world’s attention, including in Indonesia. This study discusses opportunities and challenges of decarbonization initiatives in the electricity sector by conducting traditional reviews of various publications from direct science databases and publications from official websites of other organizations relevant to the research context. The results discuss decarbonization options by replacing coal with renewable energy. Other initiatives are also investigated in this paper to provide alternative possibilities. The study indicated that each option has challenges that can affect the success of each program.
Environmental sustainability: insight into paperless policy and integrated audit internal system
Authors: Khafid M , Suryandari D , Hidayah R , Dahlan T A , Husna D R , Kayati I N
Published: October 2023

Universitas Negeri Semarang (UNNES) is one of the higher education institutions with legal status in Indonesia that has launched conservation. Therefore, every program implemented must be based on environmental preservation. This research examines the relationship between paperless policy and the internal audit system on environmental sustainability. The research method uses primary data and secondary data. Data analysis applies a comprehensive descriptive analysis. The results showed that applying a paperless policy at UNNES reduced the amount of paper used. In addition, an integrated internal audit system can reduce paper use. The existence of an internal audit system that all units can access via the Internet can reduce paper usage figures. This non-corrosive use policy has been able to participate in preserving the environment. Hence, applying a paperless policy accompanied by providing integrated internal audit system facilities can maintain environmental sustainability.
The impact of green innovation and environmental reporting on corporate performance
Authors: Widiatami A K , Jati K W , Astuti D P , Nurkhin A
Published: October 2023

This study investigates the effect of green innovation and environmental disclosure on firm performance related to consumers and shareholders. This study uses sales growth to see firm performance related to consumers and market value added (MVA) calculations related to shareholders. We obtained a sample of 54 food and beverage industry companies listed on the Indonesia Stock Exchange (IDX) based on the purposive sampling technique. The food and beverage industry was chosen to sample this study because it is one of Indonesia’s most significant contributors to waste. This study uses path analysis panel data and the Sobel test to test the hypothesis. The test results show that green innovation significantly positively affected sales growth, while environmental reporting negatively affected. Firm size as a control variable positively affects MVA. In addition, sales growth does not indirectly affect the relationship between green innovation and environmental disclosure to MVA. This study shows that consumers are more interested in companies that engage in actual action through green innovation to reduce environmental damage. At the same time, the shareholders do not pay attention to the company’s environmental activities.
Determinants of Indonesian MSMEs’ Green Investment Choices Towards Inclusive and Sustainable Economic Growth
Authors: Prihastiwi D. A. , Fatimah A. N. , Nurcahya Y. A.
Published: October 2023

MSMEs are catalysts for economic growth in both rural and urban areas. In light of this, MSMEs should have equitable access to the numerous resources required for their innovation. However, environmental sustainability should also be considered with these developments. Therefore, it is necessary to conduct a study on the factors that influence MSMEs’ selection of green investments. This study analyses whether financial literacy and financial behaviour could determine the green investment choices in micro, small and medium enterprises (MSMEs). Data collection in this study used a survey technique for MSMEs in Magelang and received 195 respondents. Data was then analysed using multiple regression analysis. The results show that positive financial behaviour is related to more sound green investment decisions of MSMEs owners. In addition, this study also finds educational background influences the selection of MSMEs green investments. Financial behaviour can have an impact on investment innovation because MSMEs owners who pay more attention to their financial position will be able to manage risk tolerance better, so they are more attracted to more green investments. The results of this study will corroborate previous research showing that individuals with greater financial behaviour make reasonable financial decisions based on their risk preferences