bluuebunny/crossref_metadata_2025 huggingface dataset:
Session 17. Oral Presentation for: Whale detection and microseismic monitoring via DAS using submarine telecommunications cables – a case study from the NWS, Western Australia
Authors: Debens Henry A. , McCorry Denise
Published: June 2024

Presented on Wednesday 22 May: Session 17 A monitoring trial of subsea distributed acoustic sensing (DAS) conducted in the marine waters of Australia is presented. This trial explores the concept of repurposing existing submarine telecommunications cables for remote monitoring of the environment and geophysical phenomena. The data were collected from a pre-existing fibre-optic cable, 50 km in length, that links two offshore hydrocarbon production platforms off the northwest coast of Australia. Initial data analyses confirmed the ability to detect underwater sounds from various sources, including marine animals (such as baleen whales), anthropogenic activities (such as vessels), and natural geophysical phenomena (such as earthquakes). The study underscores the efficacy of DAS for capturing and locating marine mammal vocalisations, specifically highlighting signals from pygmy blue whales – a species granted the highest protection status in Australia – and Omura’s whales, both of which migrate biannually through the offshore waters of Western Australia. These findings indicate the potential of subsea DAS for detecting and tracking marine fauna regionally. Moreover, they suggest its applicability for future monitoring in support of environmental impact assessments and the development of adaptive management strategies to prevent or minimise impacts on migratory whale species from offshore industries. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 18. Oral Presentation for: Static contact angle, interfacial tension, and column height measurements for underground hydrogen storage
Authors: Muhammed Nasiru Salahu
Published: June 2024

Presented on Wednesday 22 May: Session 18 Geological porous media are key for large-scale hydrogen (H2) storage and production, where fluid interactions at interfaces and within rock formations are vital for effective gas containment. Although advancements have been achieved in comprehending structural trapping for estimating column height (CH), additional insights are required regarding how pore size impacts this estimation. Currently, CH estimates often consider seal rock potential, without including the capillary contribution from reservoir rock pore for structural trapping capacity assessment. This study measures the static contact angle (CA) on Wolfcamp (WC) Shale and interfacial tension (IFT) under modified drainage and imbibition conditions at temperatures of 30 and 50°C, pressures ranging from 500 to 3000 psia, and a salinity of 10 wt% sodium chloride. Subsequently, the static gas CH was calculated, accounting for contributions from the caprock pores alone and both the caprock and reservoir, to assess the structural sealing capacity of the caprock layer. The experimental procedures are comprehensively detailed in this paper. The outcome indicates that the static CA after drainage for H2)/brine/WC shale rises with pressure as the static CA after imbibition decreases. Both CAs decrease with increasing temperatures. For H2/brine systems, both drainage and imbibition IFTs decline with increasing pressure and temperature. Calculated CHs reveal that lower CAs substantially impact the gas trapping capacity beneath the caprock. In summary, this study highlights the preference for the drainage method in measuring IFT and CA to evaluate the potential structural trapping capacity of injected gas by the overlying caprock. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 20. Oral Presentation for: Australia’s 2024 decommissioning landscape
Authors: Sadler Shaun
Published: June 2024

Presented on Wednesday 22 May: Session 20 Australia’s decommissioning workload has continued to grow at a pace in the past year, several scopes are now awarded, and significant progress is being achieved on a number of studies. However, there is still a lot to do for Australia to deliver its decommissioning outcomes efficiently, safely and to best achievable standards. This paper will provide an update on decommissioning developments across Australia as well as highlighting some key activities helping grow a sustainable local industry. Coming off a low historic volume of activity of the previous decade, Australia’s decommissioning industry has had to rapidly scale and skill-up to address the significant volume of activity anticipated for the remainder of the decade. This increase has impacted the entire value chain, with everyone struggling to find experienced staff, access technologies and secure the all-important vessels to execute the work. Government is moving to support local companies grow into the industry. Regulators are working to balance societal expectations and industry plans. The service sector is mobilising into Australia, and everyone is looking for access to facilities to land equipment and to understand recycling and disposal chains. Meanwhile the workforce, keen to understand where to position themselves for the energy transition, are looking for opportunities. CODA has continued to work strategically to build the local industry. In the past 12 months, CODA has been developing a new online lookahead, completed several port studies, started to map industry skills needs and looked deeper into materials disposal and recycling. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 20. Oral Presentation for: Maximising opportunities from integration of decommissioning and offshore wind activities
Authors: Taylor Andrew
Published: June 2024

Presented on Wednesday 22 May: Session 20 The marine nature of both oil and gas decommissioning and offshore wind development creates clear opportunities for efficiencies between the two sectors. As explored by this paper, decommissioning will benefit from upgrades to port facilities for offshore wind, offshore wind will benefit from access to vessels servicing decommissioning activities over long periods of time, and both industries can collaborate to establish long-term career paths for local communities. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 25. Oral Presentation for: Monitoring geomechanical pumped storage in horizontal fluid-filled lenses with surface tiltmeters
Authors: Kasperczyk Dane
Published: June 2024

Presented on Thursday 23 May: Session 25 Geomechanical Pumped Storage is a long duration energy storage technology that assists with integrating variable renewable energy sources into the electricity grid. The concept involves cycling fluid in artificial subsurface lenses. These lenses act as high-pressure reservoirs, storing and releasing pressurised fluid to drive a turbine and generate power. Similar in nature to traditional pumped storage hydropower, but lower cost, modular, and without the specific topography requirements. This work describes the surface monitoring and analysis from several lenses manufactured in the Eagle Ford Shale at Quidnet Energy’s Castilleja pilot storage site in Texas. Up to 12 high-precision tiltmeters were used to verify dip and orientation of the lens as well as provide a predictive map of the lens geometry and symmetry or asymmetry of the lens growth. The surface tiltmeters used as a diagnostic tool for lens creation have been proven to be useful. It provides operators with confidence and feedback on fundamental lens behaviour and response. These improvements will help scale the technology to commercially viable modular energy storage systems. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 26. Oral Presentation for: Unpacking the decline: Australian E&P capital trends in a global context
Authors: Philips Anish
Published: June 2024

Presented on Thursday 23 May: Session 26 In 2015, ASX-listed exploration & production (E&P) companies raised almost A$12 billion in capital, marking a peak in their recent fundraising efforts. However, this has declined annually since, with only about A$1.2 billion raised in 2022, despite lower Reserve Bank of Australia (RBA) interest rates compared to 2015. The investment ratio, measuring investments relative to cash from operations, plummeted from 187% in 2015 to 20% in 2022. Globally, public E&P players averaged 97% in 2015 and 31% in 2022. Going forward, we expect Australia’s investment ratio to average 31% between 2023 and 2025, compared to the global average of 49%. This paper explores Australian E&P capital expenditure trends against global patterns, attributing the decline to factors such as environmental and legal risks, limited access to capital, regulatory hurdles, and approval delays. For instance, offshore environment plan approvals now take over a year on average, compared to 4 months in 2017. Despite high oil and gas prices, spare infrastructure capacity, and domestic gas market shortfalls, investment activity in Australia wanes. Additionally, merger & acquisition (M&A) activity, often indicating industry interest, dropped by nearly half in Australia in 2022 compared to 2018. This paper examines why Australia lags in capital spend, citing environmental, regulatory, and approval challenges. While global trends show increased spending, Australia’s oil and gas sector faces headwinds in attracting investments and M&A activity. To access the Oral Presentation click the link on the right. To read the full paper click here
Emission Reductions Visual Presentation R09: Monitor and reduce emissions to meet compliance and sustainability goals
Authors: Castelijns Nicolas
Published: June 2024

Emission Reductions Visual Presentation R09 In today’s climate-conscious world, companies across the globe continue to push to optimise energy use and reduce or eliminate their greenhouse gas emissions. Investments aimed at emission monitoring and reduction are driven by the need to optimise consumption of electricity, gas, oil, and water to meet emissions reduction targets and sustainability goals. Tracking and reducing emissions can improve process uptime through predictive maintenance and reduce product losses across the process. Methane emissions are in particular focus as methane is more than 25 times as potent as carbon dioxide at trapping heat in the atmosphere. The U.S. Environmental Protection Agency stated that a third of methane emissions in North America come from the industrial sector, and similar figures come from the European Commission. It is no wonder that government and industry are laser-focussed on improving their approach to the reduction of methane emissions. As companies drive their own corporate standards to achieve net zero emissions, there is also a need to comply with existing and upcoming governmental emissions standards and regulations, and report emissions on a periodic basis. The trend to move fugitive emissions monitoring from periodic to continuous provides operators with a greater insight into emissions sources which drives efficiencies through the reduction of lost product and a more predictive approach to maintenance. Investors are increasingly focussed on environmental, social, and governance (ESG) reporting and favouring companies that can demonstrate strong ESG performance. Fugitive emission leaks can translate into billions of dollars of lost productivity annually, and serious occupational accidents. To access the Visual Presentation click the link on the right. To read the full paper click here
Geoscience Visual Presentation G06: Exploration potential of Papua New Guinea – latest multiclient 3D provides new insight into the underexplored Papuan Basin over the Papuan and Eastern Plateaus
Authors: Choi Tad
Published: June 2024

Geoscience Visual Presentation G06 The Gulf of Papua, part of the regional Papuan Basin, is characterised by extensional to passive margin tectonics from the Triassic to Late Oligocene and collisional tectonics from the Late Oligocene until the present day. The basin has experienced rapid clastic deposition in the late Neogene which covers an underlying extensive Miocene carbonate shelf with local bioherms and associated carbonate facies. Underlying the carbonates, an array of deformed and complex rift basins are present, with potential petroleum plays in undifferentiated Mesozoic sediments which onlap basement highs. The Miocene carbonates are the primary exploration targets, along with Pliocene clastic turbidite sediments in the Fly River Delta, Western Gulf of Papua. It is postulated that these were charged by Mesozoic marine–deltaic/terrestrial source rocks that were deposited during the opening of the Coral Sea. The offshore Papuan Basin is underexplored and the Gulf of Papua play types seen in the onshore Aure Fold Belt and offshore Fly River Platform could potentially extend offshore into the Coral Sea area. New broadband Pre‐Stack Depth Migration seismic data covering a part of the Eastern and Papuan Plateaus reveals new insights into the structural development of the region, rift basin geometries, configuration, and association of rift clastics and post-rift carbonates. Internal carbonate features can be observed on the new seismic data set, and new plays in the yet undifferentiated rift sediments of Mesozoic age are proposed in this study. To access the Visual Presentation click the link on the right. To read the full paper click here
Global hotspots of endemicity, rarity and speciation of aquatic macrophytes
Authors: Lobato-de Magalhães Tatiana , Murphy Kevin , Tapia Grimaldo Julissa , Davidson Thomas A. , Molina-Navarro Eugenio , de-Nova José Arturo , Efremov Andrey
Published: June 2024

Context Most aquatic macrophytes are ecozone-endemic species, and approximately two-thirds of them have rare occurrence at global scale. These small-range plants are seriously under-studied at macroecological scale, despite their marked vulnerability to extinction through habitat loss and climate change. Aims To identify global hotspots of endemism and rarity of aquatic macrophytes and examine the factors that resulted in speciation hotspots of macrophytes in some areas of the planet. Methods We analysed a database of 3499 macrophyte species to locate speciation hotspots and assess the biogeographic and environmental drivers that maintain ecozone-endemic, and globally rare species within their current limited global areas of occupancy. Key results Ecozone-endemic and globally rare macrophyte species hotspots across the planet showed similar occurrence patterns and drivers among ecozones. Ecozone environmental conditions, particularly harsh environments, influenced macrophyte phylogenetic diversity and structure. Most macrophyte species diversification is recent (<10 million years ago). A negative association with bird-mediated zoochory was seen for endemicity and rarity hotspots. Conclusions This study identified hotspots of endemicity and rarity, and potential cradle and museum speciation areas. Implications Our findings could inform global action to conserve the macrophyte diversity of wetlands, and other inland aquatic habitats, across the world.
Crip translingualism
Authors: Canagarajah Suresh
Published: June 2024

Forms of
immobility both limit unqualified human agency and enable diverse channels of mobility. In this sense, mobility and immobility
work together. Certain philosophical movements such as Southern theories and disability studies treat constraints, sedentariness,
and boundaries as needing to be respected and accommodated in any inquiry. This article draws from these schools to theorize
disruptions and constraints as resources in the circulation of languages, texts, and meanings. To index this generative role of
constraints in communication, I adopt the term “crip” from theorizations in disability studies. “Crip” invokes the paradoxical
reality that while being crippled poses disruptions in mobility, this rupture also generates new knowledge and possibilities into
the flow of life (McRuer, 2006). This article explains how crip
translingualism would treat ruptures, constraints, and boundaries as resourceful for meaning making. This is a
corrective to certain previous theorizations that have treated translingualism as based on unrestricted flows and fluidities,
influenced by dominant orientations to mobility. I illustrate from a classroom literacy interaction where the ruptures posed by
the heritage languages of multilingual students motivated everyone to adopt creative strategies to expand the meaning of
“meaning,” redefine literacy as negotiated, and develop ethical dispositions to collaborate in communicating across language
boundaries. I argue that the incomprehensions and vulnerabilities created by language diversity actually motivate everyone to
develop strategies to creatively read and write. In this manner, constraints don’t stifle the text or students, but mobilize new
flows of meanings and interactions.
Backchannels in the lab and in the wild
Authors: Nguyen Allison , Guydish Andrew J. , Fox Tree Jean E.
Published: June 2024

Backchannel choices affect conversational development. Some backchannels invite interlocutors to continue to the
next part of what they are saying and others invite them to elaborate on what they have just said. We tested how communicative
modality (audiovisual, audio, text), environmental setting (wholly in-lab, partially in the wild), and conversational goals
(on-task, off-task) influenced backchannel usage by participants. We found that backchannel production depends on modality,
setting, and goals. For example, we found that specific backchannels played a more prominent role in self-motivated dialogue.
Knowledge of how backchannels are used has both theoretical and practical implications.
Aggression and disagreement in public communication
Authors: Lombardi Vallauri Edoardo
Published: June 2024

The persuasive effectiveness of implicit strategies, associated
with reduced epistemic vigilance, may lead to their exploitation in conveying
doubtful information in advertisement and propaganda. In political
communication, presuppositions tend to specialize for the conveyance of
questionable opinions and self-praise, while implicatures reveal a preferential
association with face-threatening contents in general, where implicitness can
allow speakers to count less evidently as offenders, at the same time being able
to convey contents that can discredit the opponent.

In public debates, speakers do not necessarily aim at convincing
the opponent, but at shaping the beliefs of the public at home. In Italian
broadcast political debates, implicatures and presuppositions are used exactly
with this function. Confirming this pattern, participants in public debates
often “intercept” the opponent’s implicatures and make them explicit in order to
reduce the persuasiveness effected by their being implicit. Sometimes this also
offers the opportunity to provide explicitations that are different from the
original implicature, caricaturizing the position of the opponent with a
strawman effect.
The evidential dimension of implicitly conveyed disagreement in
political debates
Authors: Masia Viviana
Published: June 2024

The idea that manipulation relies more heavily on implicit than
on explicit communication has been the plank of several earlier and recent
debates on argumentation and speaker roles in interactions. The present
contribution will inquire into the selective nature of the use
of implicit communication in political discourse; notably, analyzing the
distribution of presuppositions and implicatures in two political debates, it
will be argued that the use of these two implicit communicative devices – and,
particularly, that of presupposition – is likely to correlate
with the expression of disagreement, notably through aggressive and blasting
contents, more often than with other content types. This tendency will be
accounted for by considering the evidential meaning presuppositions and
implicatures add to an utterance, which contributes to modulating both speaker’s
commitment to truth and source identification on the part of the receiver. Data
also show that, when face-threatening contents are exchanged, presuppositions
epitomize by far the most preferred strategy in both debates.
Indicator of abnormal cathode electron emission state with gas flow in Hall thrusters
Authors: Li Jingjing , Zhou Liwei , Hu Yanlin , Fan Haotian , Ma Haochen , Wei Liqiu , Ding Yongjie
Published: June 2024

The accurate diagnosis of abnormal electron emission state in hollow cathodes is crucial for the stable operation of Hall electric propulsion systems. In this study, a method of reducing the cathode working gas flow rate was used to simulate abnormal working conditions in which the cathode electron emission state (CEES) was deteriorating. By analyzing and comparing the oscillation signals under abnormal and steady-state working conditions, it was found that as the CEES deteriorated, the power content of the breathing oscillation decreased in the 1–40 kHz frequency band, and the main frequency decreased; in contrast, the power content of the transit-time oscillation increased in the 100–500 kHz range, and the main frequency was on the rise. Combined with the current growth rate analysis of breathing and transit-time oscillations, when the cathode gas flow rate decreases, the CEES deteriorates, the coupling voltage drop increases, and the potential drop in the channel decreases. The electron temperature and nonlinear power absorption of the electrons decrease, leading to a decrease in the growth rate of breathing oscillations and the breathing oscillation weakens; however, the time-averaged ion velocity and ion sound velocity in the channel decrease simultaneously, but the ion velocity decreases significantly faster than the ion sound velocity, leading to an increase in the growth rate of the transit-time oscillation, and the transit-time oscillation strengthen. Through comparison of the oscillation signals under different working conditions, such as varied anode flow rate, anode voltage, magnetic induction, it was proven to be a unique feature of CEES deteriorates, and can be used as an indicator of CEES deteriorates during the on-orbit operation of the Hall-effect thrusters.
Influence of duty cycle on the physicochemical characteristics of an AC-driven argon plasma jet and its impact on hydrogen peroxide production and cell viability
Authors: KC Sushil Kumar , Derrick-Roberts Ainslie L K , Hong Sung-Ha , Ghimire Bhagirath , Oh Jun-Seok , Szili Endre J
Published: June 2024

This paper investigates how the duty cycle influences the production of hydrogen peroxide (H2O2) in an alternating current (AC)-driven plasma jet. H2O2 is a major reactive oxygen species produced by plasma jets in medicine and is a biological important molecule because it can intervene in cellular signaling processes important for disease treatment. In this study, duty cycles were varied from 9% to 72%, which correlated with an increase in the plasma’s dissipated power and UV photon energy density, and consequently an increase in the production of high energy plasma components important for producing H2O2 through electron collision and UV photolysis reactions. Cell media treated with the plasma jet at higher duty cycles correlated with a decrease in the viability of HaCaT keratinocyte skin cells. The AC-driven plasma jets were shown to be operated optimally at a biocompatible gas temperature of below 40 °C whilst still maintaining efficiency in H2O2 production. Overall, the data presented in this study might find use for the future of optimization of the electrical properties of AC-driven plasma jets in plasma medicine.
Enhancement of superconductivity in Zr2S2C arising from phonon softening on transition from bulk to monolayer
Authors: Jamwal Prarena , Ahuja Rajeev , Kumar Rakesh
Published: June 2024

We report a new compound, Zr2S2C, belonging to the transition metal carbo-chalcogenide (TMCC) family. Through first-principles calculations, our analysis of phonon dispersion spectra indicates that the compound is dynamically stable in both bulk and monolayer forms. We systematically investigated the electronic structure, phonon dispersion, and electron–phonon coupling (EPC) driven superconducting properties in bulk and monolayer Zr2S2C. The results demonstrate the metallic character of bulk Zr2S2C, with a weak EPC strength (λ) of 0.41 and superconducting critical temperature (

T

c

) of ∼3 K. The monolayer Zr2S2C has an enhanced λ of 0.62 and

T

c

of ∼6.4 K. The increased λ value in the monolayer results from the softening of the acoustic phonon mode. We found that when biaxial strain is applied, the low energy acoustic phonon mode in monolayer becomes even softer. This softening leads to a transformation of the Zr2S2C monolayer from its initial weak coupling state (λ = 0.62) to a strongly coupled state, resulting in an increased λ value of 1.33. Consequently, the superconducting critical temperature experiences a twofold increase. These findings provide a theoretical framework for further exploration of the layered two-dimensional TMCC family, in addition to offering valuable insights.
Analyses of hydrogen local environments in metals and intermetallic compounds using inelastic neutron scattering calculations based on first-principles hydrogen adiabatic potentials
Authors: Tatsumi Kazuyoshi , Okudaira Takuya , Kofu Maiko , Rozyczko Piotr
Published: June 2024

This study re-evaluates the theoretical approach to analyzing inelastic neutron spectra of hydrogen-containing metals and intermetallic compounds. Previously, these analyses utilized hydrogen quantum nuclear states, modeled as solutions to the Schrödinger equation. The potential surfaces in these models were approximated from the total energies derived from first-principles electronic structure calculations. The current study improves upon this method by employing more efficient and accurate treatments for sampling the potential surface. It utilizes symmetrically irreducible sampling points arranged on densely populated mesh grids for the first-principles calculations. A comparative analysis of the theoretical predictions with experimental spectra for hydrides of Ti2Sb and Ti3Sb, as well as a LaNi5 hydrogen primary solid solution, demonstrates that this approach is promising for elucidating the unknown local environments of hydrogen atoms in systems where the approximate potential well describes the hydrogen quantum states.
Recent progress in aqueous aluminum-ion batteries
Authors: Wang Bin , Tang Yu , Deng Tao , Zhu Jian , Sun Beibei , Su Yun , Ti Ruixia , Yang Jiayue , Wu Wenjiao , Cheng Na , Zhang Chaoyang , Lu Xingbao , Xu Yan , Liang Junfei
Published: June 2024

Aqueous aluminum-ion batteries have many advantages such as their safety, environmental friendliness, low cost, high reserves and the high theoretical specific capacity of aluminum. So aqueous aluminum-ion batteries are potential substitute for lithium-ion batteries. In this paper, the current research status and development trends of cathode and anode materials and electrolytes for aqueous aluminum-ion batteries are described. Aiming at the problem of passivation, corrosion and hydrogen evolution reaction of aluminum anode and dissolution and irreversible change of cathode after cycling in aqueous aluminum-ion batteries. Solutions of different research routes such as ASEI (artificial solid electrolyte interphase), alloying, amorphization, elemental doping, electrolyte regulation, etc and different transformation mechanisms of anode and cathode materials during cycling have been summarized. Moreover, it looks forward to the possible research directions of aqueous aluminum-ion batteries in the future. We hope that this review can provide some insights and support for the design of more suitable electrode materials and electrolytes for aqueous aluminum-ion batteries.
Analysis and simulation of bulk polarization mechanism in p-GaN HEMT with AI component gradient buffer layer
Authors: Liu Shijin , Wang Ying , Fei Xinxing , Yu Chenghao , Guo Haomin
Published: June 2024

In this paper,bulk polarization mechanism and radiation simulation of the Al component gradient buffer layer (GBL) and constant buffer layer (CBL) of p-GaN HEMT (p-GaN GBL-HEMT and p-GaN CBL-HEMT) are analyzed and studied. It is found that the p-GaN GBL-HEMT can significantly reduce the buffer leakage current. The linear gradient amplitude (the range of linear gradients of Al components vertically in the buffer) of 20%–25% Al components can significantly increase the breakdown voltage (V
BK) of the device, up to 1312 V. Simultaneously, although the p-GaN GBL-HEMT reduces the 2DEG concentration, the device still has a specific on-resistance (R
ON,sp) and drain saturation current (I
DS,sat) equivalent to the p-GaN CBL-HEMT due to the conductivity modulation effect. Its Baliga figure of merit is up to 2.27 GW cm−2. Finally, through the SEE simulation and the bulk polarization mechanism analysis, it is found that the drain transient current (I
DS,trans) by the identical incident particles in the p-GaN GBL-HEMT is lower than that in the p-GaN CBL-HEMT, and the I
DS,trans decreases with the increase of the Al components gradient amplitude. Therefore, the p-GaN GBL-HEMT provides a new idea for improving the electrical performance and SEE hardening.
Minority-carrier transport through an isotype amorphous-crystalline Ge2Sb2Te5 heterojunction under forward bias
Authors: Nagendra Arun , Trombley Jeremy B , Chan Erwin H W
Published: June 2024

To predict possible minority-carrier effects in multi-level phase change memory devices, minority-carrier transport through an isotype amorphous-crystalline Ge2Sb2Te5 heterojunction under forward bias is studied for the first time. Electron thermionic emission, thermal generation, drift, diffusion, radiative recombination, Auger recombination, Schockley–Read–Hall recombination via conduction band tails, valence band tails, acceptor-type mid-gap, donor-type mid-gap and multivalent defect distributions, as well as surface recombination are considered in the construction of the steady-state Continuity Equation relevant to the representative amorphous-crystalline Ge2Sb2Te5 heterojunction, which is then numerically solved at 0.15 V and 0.40 V using solar cell capacitance simulations. Provided that radiative recombination is negligible and defect distributions within the band gap of either layer are energetically localised, the simulated electron concentration, electron current density and electron quasi-Fermi level distributions across the heterojunction reveal that transport through the amorphous layer limits electron flow through the device. At low applied bias, net recombination and diffusion within the quasi-neutral region (QNR) of the amorphous layer dominate, whereas at larger applied bias, drift across the QNR, due to the electric field induced by the significant majority-carrier current density, as well as surface recombination at the amorphous layer contact contribute significantly. Within the crystalline layer, net generation of electrons supplies the amorphous layer at all biases, assuming that the crystalline layer contact does not limit electron transport. Thus, the effect of forward bias on the dominant transport mechanisms through the amorphous-crystalline Ge2Sb2Te5 heterojunction demonstrated herein represents the key contribution of this paper.
Three-dimensional phononic crystals with self-similar structures
Authors: Gong Feilong , Li Qi , Kong Yue , Sun Xiaomei , Xiao Zifei
Published: June 2024

Acoustic metamaterials have the advantages of designability, strong pertinency, small size and good effect, and have good application value in solving the problem of sound insulation and noise reduction. Phononic crystals with wide bandgap and multi-bandgap can inhibit elastic wave propagation to some extent. In this study, a three-dimensional phononic crystal model with self-similar properties is designed by using fractal method. First, an initial unit is constructed, then the arm of the initial unit is replaced with the structure itself to form a self-similar structure. The self-similar model can block sound waves in the wide band and multi-band range. By changing the structure shape and size of phononic crystal, the sound wave blocking in different frequency range is also studied. At the same time of continuous optimization of the structure, the variation rules of the model band structure under different parameters are summarized. To find the good parameters of broadband and multi-band sound wave blocking, so as to achieve the effect of vibration isolation and noise reduction. The finite element method is used to simulate the vibration of the model to verify the existence of elastic wave bandgap. Phononic crystals have a good prospect in the field of sound insulation and noise reduction.
Plasma-solution synthesis of cobalt oxides
Authors: Smirnova K V , Shutov D A , Ivanov A N , Manukyan A S , Rybkin V V
Published: June 2024

The production of nanosized oxide materials is an important practical problem. This is due to the fact that many of these substances are intensively used as catalysts, microelectronic devices, medical applications, etc. Among the various methods for their production, methods based on the use of gas-discharge plasma are the least studied. But these methods, compared to others, have a number of significant advantages. Among them, the main ones are high process rates and the absence of additional reagents. Therefore, in this work the regularities of the processes of formation of insoluble compounds under the action of a direct current discharge of atmospheric pressure in air on aqueous solutions of cobalt (II) nitrate have been studied. The solutions served as the cathode and anode of the discharge. The discharge was excited by applying a high voltage to two pointed titanium electrodes placed above the liquid anode and liquid cathode in the H-shaped cell. The range of discharge currents was (20–80) mA, and the range of concentrations was (20–60) mmol l−1. It was discovered that when a discharge acts on a liquid anode, a colloidal solution is formed in it, the destruction of which leads to the formation of precipitates. Based on measurements of the kinetics of consumption of Co2+ ions (spectrophotometric method) and the power inputted in the discharge, the rates of this process, effective rate constants, as well as the degree of conversion of Co2+ ions and energy yields of conversion were determined. These parameters depended on the discharge current and the initial concentration of the solution. The values of the constants were ∼(0.2–6) × 10−1 s−1, the energy yields were ∼(0.2–0.5) ions per 100 eV, and the degrees of conversion were ∼(0.1–0.5). The resulting powders were analyzed by differential scanning calorimetry (DSC), x-ray diffraction (XRD), and energy-dispersive x-ray spectroscopy (EDS). The sizes of the powder aggregates were estimated from the results of scanning electron microscopy (SEM), transmission electron microscope (TEM) and Scherrer’s relation. It turned out that the resulting precipitates were a mixture of amorphous Co2+ and Co3+ hydroxides. Their calcination in air led, depending on the temperature, to the formation of predominantly cubic either CoO or Co3O4. The size of the aggregates of the calcined samples was ∼500 nm. The specific surface area of the powders, determined by the Brunauer–Emmett–Teller (BET) method, was ∼53 m2 g−1. The average pore volume and their size was ∼17 cm3 g−1 and ∼240 Å. The advantages of the proposed method over other methods are high process rates (process time ∼10 min) and the absence of any additional reagents.
Dynamic control of optical skyrmions in cylindrical waveguide
Authors: Jiang Rong-Tao , Zhao Li-Ming , Zhou Yun-Song
Published: June 2024

In recent times, the optical skyrmions have received an increasing amount of interest owing to its applications in optical manipulation, super-resolution imaging and microscopy, quantum technologies. However, few studies are focused on the dynamic control of optical skyrmions. It is found that Neel-type photonic skyrmions were discovered in evanescent electromagnetic waves. Here, we find the Bloch-type skyrmions in a three-dimensional cylindrical waveguide. By modulating the amplitude ratio of two incident vortex beams, the new types of skyrmions such as Twisted-type skyrmions and Planar-type skyrmions can be found. Further more, we have also achieved arbitrary modulation ratios of internal spin components. It is believed that our findings greatly enrich the types of photonic skyrmions and provide a method to freely control the photonic skyrmions.
New exact solitary waves for the Sasa-Satsuma model with variable coefficients
Authors: Liu Bo , Duan Zhou-Bo
Published: June 2024

In this paper, we investigate the variable coefficients Sasa-Satsuma model, which can describe the propagation of a light pulse in a cylindrical fiber. We study this model and obtain rich solutions using two separate methods. We obtain analytical Weierstrass elliptic function solutions using the Weierstrass elliptic function expansion method. Some Jacobi elliptic function solutions are obtained using the modified Jacobi elliptic function expansion method. When the Jacobi elliptic function degenerates, we obtain the corresponding trigonometric, hyperbolic function solutions and periodic solutions. We also try to take the coefficients of the equation as some functions and obtain some more complicated exact solutions, which have not appeared in previous studies. Finally, we simulate some waveform diagrams of the solutions using the computer software Mathematica and obtain periodic waves, bright and dark soliton, double solitons and some complex periodic waves. With these waveform diagrams, we can observe the dynamical behavior of the solutions more clearly.
Elastic full-waveform inversion using tools of neural networks
Authors: Zhang Wensheng , Chen Zheng
Published: June 2024

In this paper, we investigate the full-waveform inversion (FWI) for elastic wave equation as training a neural network. The forward modeling of the elastic wave equation in the time domain by the staggered-grid difference schemes can be reformulated as a process of a recurrent neural network (RNN). As a result, the FWI problem is equivalent to neural network training, and the parameter of RNN coincides with the model parameter of inversion. Furthermore, a variety of stochastic optimizers including Adgrad, RMSprop, Adam, Nadam and Admax in neural networks can be applied in the training process. The gradient of the objective function with the model parameters is computed by the technique of automatic differentiation instead of the adjoint-state method in the traditional FWI. A new objective function of FWI is also proposed. Compared to the traditional FWI methods, the developed FWI using tools of neural networks has a relatively good robustness. Numerical computations and comparisons with Marmousi model for two and three parameters simultaneous inversion are completed. The results show that the algorithms except Adgrad can yield good inversion results. The FWI framework developed in this paper has potential applications for other complex partial equations.
Effects of air damping on quality factors of different probes in tapping mode atomic force microscopy
Authors: Zeng 曾 Yu 瑜 , Liu 刘 Guo-Lin 国林 , Liu 刘 Jin-Hao 锦灏 , Wei 魏 Zheng 征
Published: June 2024

The AFM probe in tapping mode is a continuous process of energy dissipation, from moving away from to intermittent contact with the sample surfaces. At present, studies regarding the energy dissipation mechanism of this continuous process have only been reported sporadically, and there are no systematic explanations or experimental verifications of the energy dissipation mechanism in each stage of the continuous process. The quality factors can be used to characterize the energy dissipation in TM-AFM systems. In this study, the vibration model of the microcantilever beam was established, coupling the vibration and damping effects of the microcantilever beam. The quality factor of the vibrating microcantilever beam under damping was derived, and the air viscous damping when the probe is away from the sample and the air squeeze film damping when the probe is close to the sample were calculated. In addition, the mechanism of the damping effects of different shapes of probes at different tip–sample distances was analyzed. The accuracy of the theoretical simplified model was verified using both experimental and simulation methods. A clearer understanding of the kinetic characteristics and damping mechanism of the TM-AFM was achieved by examining the air damping dissipation mechanism of AFM probes in the tapping mode, which was very important for improving both the quality factor and the imaging quality of the TM-AFM system. This study’s research findings also provided theoretical references and experimental methods for the future study of the energy dissipation mechanism of micro-nano-electromechanical systems.
Exploration of microscopic physical processes of Z-pinch by a modified electrostatic direct implicit particle-in-cell algorithm
Authors: Li 李 Kaixuan 开轩 , Ning 宁 Cheng 成 , Dong 董 Ye 烨 , Xue 薛 Chuang 创
Published: June 2024

For investigating efficiently the stagnation kinetic-process of Z-pinch, we develop a novel modified electrostatic implicit particle-in-cell algorithm in radial one-dimension for Z-pinch simulation in which a small-angle cumulative binary collision algorithm is used. In our algorithm, the electric field in z-direction is solved by a parallel electrode-plate model, the azimuthal magnetic field is obtained by Ampere’s law, and the term for charged particle gyromotion is approximated by the cross product of the averaged velocity and magnetic field. In simulation results of 2 MA deuterium plasma shell Z-pinch, the mass-center implosion trajectory agrees generally with that obtained by one-dimensional MHD simulation, and the plasma current also closely aligns with the external current. The phase space diagrams and radial-velocity probability distributions of ions and electrons are obtained. The main kinetic characteristic of electron motion is thermal equilibrium and oscillation, which should be oscillated around the ions, while that of ion motion is implosion inwards. In the region of stagnation radius, the radial-velocity probability distribution of ions transits from the non-equilibrium to equilibrium state with the current increasing, while of electrons is basically the equilibrium state. When the initial ion density and current peak are not high enough, the ions may not reach their thermal equilibrium state through collisions even in its stagnation phase.
In-phase and out-of-phase spin pumping effects in Py/Ru/Py synthetic antiferromagnetic structures
Authors: Huang 黄 Zhaocong 兆聪 , Tang 唐 Xuejian 学健 , Chen 陈 Qian 倩 , Jiang 蒋 Wei 伟 , Guo 郭 Qingjie 庆杰 , Jalali Milad , Du 杜 Jun 军 , Zhai 翟 Ya 亚
Published: June 2024

The spin pumping effect in magnetic heterostructures and multilayers is a highly effective method for the generation and transmission of spin currents. In the increasingly prominent synthetic antiferromagnetic structures, the two ferromagnetic layers demonstrate in-phase and out-of-phase states, corresponding to acoustic and optical precession modes. Within this context, our study explores the spin pumping effect in Py/Ru/Py synthetic antiferromagnetic structures across different modes. The heightened magnetic damping resulting from the spin pumping effect in the in-phase state initially decreases with increasing Py thickness before stabilizing. Conversely, in the out-of-phase state, the amplified damping exceeds that of the in-phase state, suggesting a greater spin relaxation within this configuration, which demonstrates sensitivity to alterations in static exchange interactions. These findings contribute to advancing the application of synthetic antiferromagnetic structures in magnonic devices.
Mechanically mixing and oxidation layer induced by different contact surface of columnar Cu under dry sliding condition
Authors: Chen Qiang Qiang , Li Qian , Shang Jian
Published: June 2024

The dry sliding behavior of columnar Cu with vertical orientation (VO) and horizontal orientation (HO) coupling with 1045 steel was studied. The results show that when the sliding distance is 672 m, the friction coefficient of HO Cu is 0.21 lower than that of VO Cu, and the wear rate is reduced by 0.63·10−6 g·N−1m−1; when the sliding distance is 1344 m, the friction coefficient of HO Cu is 0.10 lower than that of VO Cu, and the wear rate is reduced by 0.31·10−6 g·N−1m−1. The Fe3O4 oxide was detected on the wear surface of HO Cu by Raman spectroscopy. And it plays a greater role in lubrication and protection of friction layer. On the worn surface of VO Cu, there is obvious softening caused by thermal activation or composition mixing. This softening will lead to a significant decrease in the strength of the friction layer, and the friction coefficient and wear loss increase negatively.
Synthesis and rheological performance of shear-thickening waterborne polyurethane
Authors: Wang Dexiu , Zhang Dongming , Li Xinxiong , Lan Zhili , Zhong Wenzhou , Yin Dulin
Published: June 2024

Shear-thickening fluids (STFs) are a new type of intelligent material with excellent performance whose viscosity increase sharply with the increase of shear rate or shear stress. However, the synthesis yield of dispersed phase particles is low, and the particle re-dispersion process is challenging for the industrial production of STFs. In this work, through structural design, a waterborne polyurethane (WPU) with typical shear-thickening properties was synthesized for the first time. This synthesis process is conducive to industrial production. The rheological properties of the synthesized WPU at different concentrations, temperatures, and pH were studied using a rheometer. The results showed that the WPU exhibited typical shear-thickening behavior. However, due to the special core–shell structure of the WPU particles, the shear rate has two transition responses to the shear-thickening behavior. With increasing concentration, the shear-thickening performance of the WPU is enhanced, and the critical shear rate is decreased. For the coexistence of Brownian motion and solvation, the rheological curve of the WPU exhibits a complex response to temperature increase; its shear-thickening behavior decreases with rising temperature, but the viscosity first decreases and then increases with temperature. Due to the presence of carboxyl groups on the surface of the WPU particles, its shear-thickening performance shows a strong response to pH. By appropriately adjusting the pH, the viscosity and particle size of the WPU can be increased through the ionization of carboxyl groups, thereby enhancing the shear-thickening behavior.