bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low-frequency vibration energy harvesting: a comprehensive review of frequency up-conversion approaches
Authors: Tang Hao , Hua Chunrong , Huang Heng , Liu Weiqun , Yang Zhengbao , Yuan Yanping , Zhang Zutao 
Published: September 2022

Abstract
Along with the rapid development of low-power electronics and the Internet of Things, vibration energy harvesting is attracting increasingly attention from both industry and academia. However, most reported energy harvesters are inefficient in real applications where excitation sources mostly are unpredictable and low frequency. To harness low-frequency vibration energy, the concept of frequency up-conversion is proposed and a variety of designs and analysis has been reported. This article presents a critical review on frequency up-conversion vibration energy harvesters (FUCHs) based on two classification principles: (a) interaction mechanisms as contact and noncontact types; and (b) excitations as type of inertial vibration and type of direct loading. Furthermore, we illustrate the applications of FUCHs designed for harvesting energy from the low-frequency human motions and propose the feasible future research directions of FUCHs.
Single-photon induced symmetry breaking of the electron localization and photoelectron directional emission in the dissociative ionization of H2
Authors: Wang Jun-Ping , Zhang Zhao-Han , He Feng 
Published: September 2022

Abstract
By numerically solving the non-Born–Oppenheimer time-dependent Schrödinger equation of H2 exposed to an isolated EUV laser pulse, we demonstrate the photoionization associated with the 2sσ

g
and 3pσ

u
dissociative states of

H

2

+

. The two asymptotically degenerate pathways with opposite parities may interfere and end up with the same kinetic energy release, resulting in the asymmetric electron localization on two nuclei. Due to dipole selection rule, the emitted photoelectron has the opposite parity with the associated

H

2

+

, and thus is also on the coherent superposition of states with odd and even parities, leading to the asymmetric directional emission of the photoelectron. The asymmetry is fundamentally determined by the phase difference of the 2sσ

g
and 3pσ

u
dissociation channels.
Generation of gravitational waves from freely decaying turbulence
Authors: Auclair Pierre , Caprini Chiara , Cutting Daniel , Hindmarsh Mark , Rummukainen Kari , Steer Danièle A. , Weir David J. 
Published: September 2022

AbstractWe study the stochastic gravitational wave background (SGWB) produced by freely decaying vortical turbulence in the early Universe. We thoroughly investigate the time correlation of the velocity field, and hence of the anisotropic stresses producing the gravitational waves. With hydrodynamical simulations, we show that the unequal time correlation function (UETC) of the Fourier components of the velocity field is Gaussian in the time difference, as predicted by the “sweeping” decorrelation model. We introduce a decorrelation model that can be extended to wavelengths around the integral scale of the flow. Supplemented with the evolution laws of the kinetic energy and of the integral scale, this provides a new model UETC of the turbulent velocity field consistent with the simulations. We discuss the UETC as a positive definite kernel, and propose to use the Gibbs kernel for the velocity UETC as a natural way to ensure positive definiteness of the SGWB. The SGWB is given by a 4-dimensional integration of the resulting anisotropic stress UETC with the gravitational wave Green's function. We perform this integration using a Monte Carlo algorithm based on importance sampling, and find that the result matches that of the simulations. Furthermore, the SGWB obtained from the numerical integration and from the simulations show close agreement with a model in which the source is constant in time and abruptly turns off after a few eddy turnover times. Based on this assumption, we provide an approximate analytical form for the SGWB spectrum and its scaling with the initial kinetic energy and integral scale. Finally, we use our model and numerical integration algorithm to show that including an initial growth phase for the turbulent flow heavily influences the spectral shape of the SGWB. This highlights the importance of a complete understanding of the turbulence generation mechanism.
Hierarchical merger of primordial black holes in dwarf galaxies
Authors: Erfani Encieh , Gomez-Aguilar Tadeo D. , Hidalgo Juan Carlos 
Published: September 2022

Abstract
We study the merger history of primordial black holes (PBHs) in a scenario where they represent the dominant dark matter component of a typical dwarf galaxies' core. We investigate the possibility of a sequence of collisions resulting in a hierarchical merger of black holes, and look at the final mass spectrum in such clusters, which initially present a monochromatic (single-mass) PBH population. Our study shows that the merging process results in the transfer of about 40% of the total mass of the core to the merger products regardless of the initial mass of PBHs, with about 5% of energy radiated out in the form of gravitational waves. We find that, in the lighter mass limit, black holes up to eight times more massive than the original population can be formed within a Hubble time.
New Apsidal Motion in Four Eccentric Eclipsing Binaries: V610 Car, V944 Cep, V2815 Ori and V1260 Tau
Authors: Bulut Ahmet 
Published: September 2022

Abstract
This paper presents an apsidal motion analysis. The apsidal motion analysis of the eccentric eclipsing binaries V610 Car (P = 4.84 days), V944 Cep (P = 6.56 days), V2815 Ori (P = 2.13 days), and V1260 Tau (P = 5.43 days) was performed using minima times from the O−C Gateway database, ASAS-3, ASAS-SN, and TESS, following Lacy's approach. The rates of change of periastron longitude were found to be 0.0253 ± 0.0041, 0.0347 ± 0.0015, 0.0288 ± 0.0010 and 0.0294 ± 0.°0079 cycle−1, respectively. From the light curve study, the first photometric mass ratio of V944 Cep was found to be q = 1.4994 ± 0.0012. A new light curve of V944 Cep was obtained using TESS data. The first absolute dimensions of V944 Cep were M
1 = 1.10 ± 0.01 M
⊙, M
2 = 1.64 ± 0.02 M
⊙, R
1 = 2.04 ± 0.37 R
⊙, R
2 = 3.77 ± 0.67 R
⊙ for the hotter primary component (T
1 = 4925 K), and M
1 = 1.04 ± 0.01 M
⊙, M
2 = 1.57 ± 0.02 M
⊙, R
1 = 2.26 ± 0.36 R
⊙, R
2 = 3.74 ± 0.59 R
⊙ for the cooler primary component (T
1 = 4475 K). For V610 Car, V944 Cep, V2815 Ori and V1260 Tau, the apsidal motion periods were found to be 188 ± 26 yr, 186 ± 8 yr, 73 ± 3 yr and 182 ± 38 yr, respectively. For V944 Cep, the internal structural constants of the component stars

log

k2,obs = −2.05 ± 0.01 and

log

k2,theo = −1.83 for hotter primary component and

log

k2,obs = −1.97 ± 0.01 and

log

k2,theo = −1.89 for cooler primary component were calculated.
Climate clubs and carbon border adjustments: a review
Authors: Overland Indra , Sadaqat Huda Mirza 
Published: September 2022

Abstract
Nobel Memorial Prize winner William Nordhaus and others have proposed a climate club as the ultimate climate-mitigation measure. Meanwhile, the European Union (EU) is pressing on with the creation of a carbon border adjustment mechanism (CBAM) that would put pressure on the rest of the world to introduce the same level of carbon pricing as the EU. There are strong linkages between the concepts of a climate club and CBAM. However, the EU long studiously avoided referring to a climate club in its official communication, and the relationship between the two concepts remains unclear. This study seeks to clarify the relationship through a systematic review of the climate club and carbon border adjustment literatures to highlight synergies and contradictions, reduce fragmentation, and increase actionability. A tailored Boolean search string is used to extract relevant literature, which is then categorised along eight parameters. The VOSviewer network analysis and visualisation software is used to examine cross-citations and bibliographic coupling. The review finds that there are connections between the objectives, methods and concerns of the two branches of literature but that there are divergences in terms of conceptual roots, disciplinary frames and the views that authors take of CBAM/a climate club. Only 7% of the studies relate to international relations theory. Several large emitters, geopolitically important states and developing countries are ignored by the literature. Although the cooperation/resistance of Asian countries will be decisive for the fate of any climate club initiative, only 15% of authors are based in Asia and Western scholars dominate the field. A five-pronged research agenda is proposed to address the identified gaps: enhanced interaction between the fields of research, coverage of a broader range of countries, additional analysis by Asia-based researchers, more contributions from political science and international relations scholars and further work on how to calculate tariffs.
The persistence of household energy insecurity during the COVID-19 pandemic
Authors: Konisky David M , Carley Sanya , Graff Michelle , Memmott Trevor 
Published: September 2022

Abstract
This study analyzes household energy insecurity in the United States during the first year of the COVID-19 pandemic. Previous research is limited by mostly cross-sectional research designs that do not allow scholars to study the persistency of this specific type of material hardship. We fill this gap by analyzing data from an original, nationally-representative, panel survey of low-income households. We find high levels of energy insecurity during the first year of the COVID-19 pandemic, especially during the initial months when the economic dislocation was at its height, and that many low-income households experienced it on multiple occasions during this period. We also identify disparities: households with people of color, very low-income, children aged five years and younger, with someone who relies on an electronic medical device, and those living in deficient housing conditions were more likely to experience energy insecurity. Households with these characteristics were also more likely to suffer from energy insecurity on a persistent basis through the first year of the pandemic.
Semiclassical energy transition of driven chaotic systems: phase coherence on scar disks
Authors: Ozorio de Almeida Alfredo M 
Published: September 2022

Abstract
A trajectory segment in an energy shell, which combines to form a closed curve with a segment in another canonically driven energy shell, adds an oscillatory semiclassical contribution to the smooth classical background of the quantum probability density for a transition between their energies. If either segment is part of a Bohr-quantized periodic orbit of either shell, the centre of its endpoints lies on a scar disk of the spectral Wigner function for a single static energy shell and the contribution to the transition is reinforced by phase coherence. The exact representation of the transition density as an integral over spectral Wigner functions, which was previously derived for the special case where the system undergoes a reflection in phase space, is here generalized to arbitrary unitary transformations. If these are generated continuously by a driving Hamiltonian, there will be a finite lapse in the driving time for the transition to start, until the initially nested shells touch each other and then start to overlap.The stationary phase evaluation of the multidimensional integral for the transition density selects the pair of matching trajectory segments on each shell, which close to form a piecewise smooth compound orbit. Each compound orbit shows up as a fixed point of a product of mappings, that generalize Poincaré maps, on the intersection of the shells. Thus, the closed compound orbits are isolated if the original Hamiltonian is chaotic. The actions of the compound orbits depend on the driving time, or on any other parameter of the transformation of the original eigenstates.
Energy transitions driven by phase space reflection operators
Authors: Ozorio de Almeida Alfredo M 
Published: September 2022

Abstract
Phase space reflection operators lie at the core of the Wigner–Weyl representation of density operators and observables. The role of the corresponding classical reflections is known in the construction of semiclassical approximations to Wigner functions of pure eigenstates and their coarsegrained microcanonical superpositions, which are not restricted to classically integrable systems. In their active role as unitary operators, they generate transitions between pairs of eigenstates specified by transition Wigner functions (or cross-Wigner functions): the square modulus of the transition Wigner function at each point in phase space is the transition probability for the reflection through that point.
Coarsegraining the initial and final energies provides a transition probability density as a phase space path integral. It is here investigated in the simplest classical approximation involving microcanonical Wigner functions. A reflection operator generates a transition between a pair of energy shells with a probability density given by the integral of the inverse modulus of a Poisson bracket over the intersection of a shell with the reflection of its pair. The singularity of the pair of Wigner functions at their dominant caustics is nicely integrable over their intersection, except for a single degree of freedom. Even though this case is not directly relevant for future investigations of chaotic systems, it is shown here how the improved approximation of the spectral Wigner functions in terms of Airy functions resolves the singularity.
An optical-digital method of noise suppression in digital holography
Authors: Cheremkhin Pavel A , Evtikhiev Nikolay N , Kozlov Alexander V , Krasnov Vitaly V , Rodin Vladislav G , Starikov Rostislav S 
Published: September 2022

Abstract
Digital holography is widely used for the fast and accurate reconstruction of objects and three-dimensional (3D)-scene characteristics, such as intensity, depth locations, density, temperature, refractive index, etc. There are various types of noise in digital holography, including speckle noise, zero order and twin image, camera shot noise, and fixed-pattern noise. Therefore, additional hologram processing is required to obtain a high-quality reconstructed image. This paper proposes an optical-digital method of noise suppression in digital holography. First, a set of uncorrelated holograms is registered. The reconstructed images are treated as a 3D array, to which a 3D filter is then applied. A 3D median filter is used in this study; however, other 3D filters based on weighted averages can also be utilized. The proposed method is verified using computer-generated and optically registered digital Fresnel holograms. Even with a small number of images, the method significantly improves the quality: the normalized standard deviation was decreased by up to 3–10 times and the speckle contrast was reduced by more than six times. Registration of only ten holograms is sufficient to obtain a quality close to the maximum. The flexibility of the proposed method allows the ratio of the reconstruction quality to be varied according to the processing time.
Enhanced synthesis of Mg(OH)2 hexagonal nanosheets using Mg powder and H2O2 solution and an observation of its NH3 sensing behaviour at room temperature
Authors: Vuong Dang Duc , Ung Le Tung , Nghi Nguyen Thanh , Phuoc Luong Huu , Khoa Cao Tien , Hien Vu Xuan , Chien Nguyen Duc 
Published: September 2022

Abstract
Magnesium is one of the most common metals in the Earth’s crust, so Mg(OH)2 nanomaterials made directly from magnesium metal have a wide range of applications. Mg(OH)2 nanosheets can be synthesised directly from Mg powder and H2O2 solution below 200 °C. The thickness of these plates decreases as the sample processing temperature increases. The optical bandgap of the synthesised samples ranges from 5.0 eV to 5.7 eV. At 25 °C, the synthesised Mg(OH)2 nanosheets could detect NH3 gas. The gas sensing mechanism was proposed and discussed, where the Mg(OH)2/H2O structure was considered a p-type semiconductor with the carrier of H3O+. The effects of parameters, such as working temperature and ambient humidity, on the electrical resistance and gas sensing properties of the Mg(OH)2 nanosheets were investigated. The NH3 sensing properties of these materials at room temperature were also compared with those of other nanomaterials.
Synthesis and characterisation of Fe3O4/MWCNT/ZnO nanocomposites covered by a soft template as a new antibacterial agent
Authors: Ulfawanti Intan Subadra ST , Taufiq Ahmad , Sunaryono Sunaryono , Hidayat Arif , Mufti Nandang , Susanto Hendra , Effendi Muhammad Chair 
Published: September 2022

Abstract
This study successfully developed a new antibacterial agent based on Fe3O4/MWCNT/ZnO nanocomposites prepared using diethylamine as a soft template. The prepared samples were characterised using x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, vibrating sample magnetometry, ultraviolet-visible spectroscopy, and antibacterial tests by the diffusion method. The results of the data analysis showed that Fe3O4/MWCNT/ZnO nanocomposites were composed of Fe3O4, MWCNT, ZnO with inverse cubic spinel, hexagonal, and hexagonal wurtzite structures, respectively. The nanocomposite particles tended to agglomerate and their size decreased with increasing volume of added diethylamine in the range of ∼23–26 nm. The nanocomposites remain stable even after being stored for more than 3 years. The nanocomposites had superparamagnetic properties with saturation magnetisation values of 24 to 31 emu g−1 and band gap values of 2.96 to 2.99 eV. The diameters of the bacterial inhibition zone of the nanocomposites were 12.57–20.38 mm, 14.25–17.25 mm, and 14.63–16.38 mm against E. coli, S. aureus, and B. subtilis, respectively. Therefore, the combination of Fe3O4, MWCNT, ZnO, and diethylamine with natural base materials such as iron sand has good potential to develop new antibacterial agents.
Effect of surfactant and etching time on p-type porous silicon formation through potentiostatic anodization
Authors: Zeb Gul , Le Xuan Tuan 
Published: September 2022

Abstract
Electrochemical anodization provides the scalability required for structuring porous silicon (PSi) layers for mass production; hence, new and feasible processes are highly sought-after. We investigate the effect of surfactant (additive) and etching time on the morphology of PSi matrix in a simplistic two-electrode anodization cell using aqueous HF electrolyte. Instead of the conventional galvanostatic mode (constant current density), we use the rarely reported technique of potentiostatic anodization (constant applied potential) for engineering PSi surface morphology. We demonstrate that under a constant applied potential, channel-like morphology, pyramids or well-ordered macropores are easily achieved through either increasing the processing time or adding a small amount of surfactant into the electrolyte. Our results provide better understanding of the mechanism underlying the formation of PSi and propose a practical solution for obtaining application-specific macrostructure of PSi.
Microstructure and texture evolution of ultra-thin high grade non-oriented silicon steel used in new energy vehicle
Authors: Fan Lifeng , Zhu Yaxian , Yue Erbin , He Jianzhong , Sun Li 
Published: September 2022

Abstract
The evolutions of microstructure and texture of ultra-thin high-grade non-oriented silicon steel for new energy vehicles were investigated in this paper, and the formation mechanism of typical recrystallized α*-fiber texture was described. The results show that: The microstructure of the hot rolled plate was inhomogeneous along the thickness direction because of the shear force and temperature gradient, resulting in the texture in each layer of the hot rolled plate appearing rotational distribution around the Goss orientation. After normalizing, the fully recrystallized microstructure was obtained, and α*-fiber texture was formed. Banded structure was obtained in the cold rolled sheet, with α-fiber texture {114}〈110〉 dominated. The typical α*-fiber texture was formed after annealing recrystallization, which mainly consist of {114}<481 > and {113}<361>. The {114}<481 > oriented grains were mainly nucleated within the deformed {114}<110 > grains and at the grain boundaries of α-fiber deformed grains, and without size, quantity and strength advantages. {111}<112 > is dominated in the early stage of recrystallization, but {114}<481 > became the main texture with size, strength and quantitative advantages in the late stage of recrystallization.
Roadmap on biomaterials for women’s health
Authors: Fogg Kaitlin , Tseng Ning-Hsuan , Peyton Shelly R , Holeman Pieper , Mc Loughlin Shannon , Fisher John P , Sutton Allison , Shikanov Ariella , Gnecco Juan S , Knight Katrina M , Slaby Emily M , Weaver Jessica D , Hashemi Nicole N , Zhang Yali , House Michael D , Vogt Brandon J , Aguado Brian A , Bradford John C , Robinson Jennifer L , Thomas Patricia K , Lau Anthony G , Oyen Michelle L 
Published: September 2022

Abstract
The application of engineering tools and techniques to studying women’s health, including biomaterials-based approaches, is a research field experiencing robust growth. Biomaterials are natural or synthetic materials used to repair or replace damaged tissues or organs or replicate an organ’s physiological function. However, in addition to in vivo applications, there has been substantial recent interest in biomaterials for in vitro systems. Such artificial tissues and organs are employed in drug discovery, functional cell biological investigations, and basic research that would be ethically impossible to conduct in living women. This Roadmap is a collection of 11 sections written by leading and up-and-coming experts in this field who review and discuss four aspects of biomaterials for women’s health. These include conditions that disproportionately but not exclusively affect women (e.g. breast cancer), conditions unique to female reproductive organs, in both non-pregnant and pregnant states, and sex differences in non-reproductive tissues (e.g. the cardiovascular system). There is a strong need to develop this exciting field, with the potential to materially influence women’s lives worldwide.