bluuebunny/crossref_metadata_2025 huggingface dataset:
Session 21. Oral Presentation for: Pioneering CCS in Australia – the CarbonNet journey
Authors: Burton Jane
Published: June 2024

Presented on Wednesday 22 May: Session 21 The CarbonNet Project (CarbonNet), a trailblazing Carbon Capture and Storage (CCS) initiative, is progressing through what has been a transformative 14-year journey. Situated in southeast Victoria, this project has evolved from an interesting concept into a multifaceted project that promises to contribute to decarbonisation via its carbon dioxide (CO2) transport and storage project. Established in 2009 and funded by both Australian and Victorian Governments, CarbonNet has been at the forefront of the CCS journey in Australia. Its primary objective is to establish a hub in the Latrobe Valley, where a diverse range of industries supply CO2 for transport through an underground pipeline to the project’s initial offshore storage site, known as Pelican, in the globally renowned Gippsland Basin. The CarbonNet journey has been marked by significant milestones, including legislative changes to accommodate its future storage goals. Knowledge sharing and regulatory engagement have also been an ongoing priority, facilitating a robust feedback loop to ensure alignment with contemporary environmental standards. Adapting to dynamic market conditions, the project is working to secure customers within the rapidly evolving CO2 market whilst seeking to create a robust business model. More recently CarbonNet has been observing the emergence of proposed offshore wind and onshore transmission projects in the Gippsland region. This explosive growth of new energy solutions within Gippsland has created challenges and opportunities for the project. Jane Burton will provide an insightful overview of CarbonNet’s remarkable evolution, highlighting the critical role it plays in the journey towards establishing a net-zero future. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 21. Oral Presentation for: Modelling CO2 storage in oil and gas reservoirs in the Gippsland Basin
Authors: Gillam Dan
Published: June 2024

Presented on Wednesday 22 May: Session 21 The Gippsland Basin has world class geology for carbon capture and storage (CCS) and a long history of oil and gas production. Depleted oil and gas fields within the Gippsland Basin that are candidates for carbon dioxide (CO2) storage are in close proximity to existing infrastructure that could be repurposed as part of a CCS project. Modelling of CO2 storage in the depleted Bream oil and gas reservoir is being progressed. Bream reservoir properties are very well understood due to extensive geological and geophysical data sets available from wells and seismic data. Additionally, the field has been through three key phases of development during its production history; oil production and gas re-injection in 1988, gas cap blowdown started in 2002, and seasonal gas storage and withdrawal started in 2012 through to field shut-in in 2020. This provides a wealth of dynamic data that is used to calibrate the reservoir models to improve our confidence in the CO2 plume prediction. However, there are also challenges in modelling CO2 storage in depleted fields. Unlike saline aquifers, CO2 can be injected into a three-phase depleted reservoir that contains residual oil and gas saturation. The key aspects of our workflow to evaluate the plume behaviour are presented in this paper. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 24. Oral Presentation for: The migration of hydrogen in sedimentary basins
Authors: Lodhia Bhavik Harish
Published: June 2024

Presented on Thursday 23 May: Session 24 Understanding the mechanisms of large-scale, subsurface hydrogen migration is essential for natural hydrogen exploration and for hydrogen storage assessment. The unique properties of hydrogen make the timescales of hydrogen migration within geological basins vary from thousands of years to days. Within the shallow Earth, diffusive and advective transport mechanisms are dependent on a wide range of parameters, including geological structure, microbial activity and subsurface environmental factors (e.g. salinity, temperature and pressure). In this study, we review the nature and timescale of hydrogen migration in geological basins. We also review the mechanisms and timescales of hydrogen migration within diffusive, advective and biologically moderated systems within the shallow Earth. We calculate maximum vertical velocity for several key rock types, including sandstone and micrite, and discuss the importance of capillary pressure in controlling the mode of hydrogen migration in sedimentary rocks. Finally, we discuss the potential application of causal analyses methods to constrain complex processes in hydrogen systems and assess the challenges of conventional reservoir modelling for hydrogen migration. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 25. Oral Presentation for: Toward less carbon-intensive, faster gas-to-market offshore development schemes a case study of using discovered resources in the Bedout Sub-basin
Authors: Wu Hongfeng
Published: June 2024

Presented on Thursday 23 May: Session 25 The Dorado and Pavo fields in the Bedout Sub-basin of the Roebuck Basin, offshore Western Australia, boast a combined 2C contingent resource of 210 MMbbls of liquid hydrocarbons and 750 bcf of gas. Their discovery represents a significant development opportunity for the Australian offshore, especially given the considerable un-risked Prospective Resources in the basin. However, Dorado faces challenges due to its high volatile oil/high condensate gas ratio gas (wet gas) accumulation and its reservoir pressure exceeding 5500 psia, necessitating a miscible gas injection strategy to maximise liquid recovery. This approach involves energy-intensive gas processing and high-pressure reinjection, leading to substantial greenhouse gas emissions. The CO2 intensity directly from Dorado compressors is estimated at 30–39 kg/bbl – on a project-level nearly double the average unit emissions of many producers. This paper explores alternative development schemes using public domain information and petroleum engineering principles to mitigate technical risks, reduce CO2 emissions, and possibly improve the economics and development timeline of the Dorado and Pavo fields. For Dorado, a simpler scheme focussing on oil production and gas delivery for domestic or liquefied natural gas (LNG) use could significantly reduce emissions. Meanwhile, Pavo might see development via a standalone FPSO, emphasising reservoir energy management through water flooding and produced water disposal, typical of conventional black oil field development. These alternatives aim for a less carbon intensive and economically viable development pathway, setting a precedent for future exploration and development in the basin. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 26. Oral Presentation for: Hydrogen carriers – transporting hydrogen from producers to export power markets
Authors: Hosey Andrea
Published: June 2024

Presented on Thursday 23 May: Session 26 As a global energy transition community there is a lot of talk about producing hydrogen in Australia, South America, the Middle East and now the USA, and transporting that as an energy source to markets such as Japan, Korea, Singapore and Europe. How will we do this, what are the carriers available, and what are the advantages and challenges of each? This is a practical assessment of the situation highlighting where we need to focus our efforts as a global community and Australia’s role in enabling hydrogen supply chains of the future to succeed. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 27. Oral Presentation for: Passive well monitoring systems and carbon, capture and storage (CCS) application
Authors: Marshall Andy
Published: June 2024

Presented on Thursday 23 May: Session 27 With an increasing number of ageing subsea wells and a tightening of global regulations for well management, assuring well integrity is a key feature of risk management for oil and gas operators. Baker Hughes, in collaboration with Sentinel Subsea, has successfully deployed patented passive well monitoring systems able to detect a range of subsea emissions and alert well owners. This early detection and warning technology harnesses the natural forces and processes of chemistry and physics but does not use any electrical power for the monitoring and detection of fluids. Static mechanical structures and the natural buoyancy of escaping fluids of interest are used to gather fluids in the subsea environment where they are detected chemically using specially developed Triggers. By using fluid-specific Triggers, systems respond only to the fluid(s) of interest, not to other fluids typically encountered around subsea assets. When the target fluid has been detected passively, a coded signal beacon (previously dormant) is mechanically released to the ocean surface using self-buoyancy where an alarm is transmitted via satellite and the responsible party alerted. Systems are currently supporting multiple major and independent operators mitigate the risks associated with subsea wells globally. Based on these experiences, this paper discusses the development process of a passive well integrity monitoring system with application for carbon, capture and storage (CCS) sites. To access the Oral Presentation click the link on the right. To read the full paper click here
Session 27. Oral Presentation for: Cost-effective and modular CO2 capture to support decarbonisation for oil and gas, industrial and hard-to-abate sectors
Authors: Pandit Jai Kant
Published: June 2024

Presented on Thursday 23 May: Session 27 Reducing emissions from the industrial and fossil fuel-based power sectors is crucial to achieving net zero emissions. These sectors contribute to ~60% of global carbon dioxide (CO2) emissions. However, there are several challenges that current CO2 capture technology faces. The use of coal in steel and cement industries produces flue gases with high CO2 content but also with nitrogen and sulfur oxides (NOx and SOx) as impurities. These impurities cause faster degradation of amine-based solvents in the current CO2 capture system. Additionally, capturing CO2 from flue gases from the hard-to-abate sector, such as steel plants, is complex as it is not easy to capture CO2 from multiple sources and different CO2 concentration flue gas streams. For cement and other kiln processes, limited availability of water/steam can add to the difficulty and cost of CO2 capture. CO2CRC’s HyCaps process, an efficient and compact hybrid of solvent absorption and membrane technology, overcomes some of these challenges. It takes advantage of the capture efficiency of the solvent system, controlled flow regime and high surface-to-volume ratio of membrane technology. The mode of interaction between gas and liquid in HyCaps limits solvent exposure to NOx and SOx, reducing solvent degradation. In HyCaps, as solvent is regenerated at a lower temperature, low-quality, low-cost waste heat can be effectively utilised to reduce operational expenditure. Successful trials at three different industrial setups and preliminary techno-economic analysis from test trial data show the HyCaps process has the potential to offer very competitive capture solutions for various industrial settings. To access the Oral Presentation click the link on the right. To read the full paper click here
Emission Reductions Visual Presentation R08: A satellite constellation dedicated to frequently monitor methane emissions from oil and gas facilities around the world
Authors: Odunsi Lola
Published: June 2024

Emission Reductions Visual Presentation R08 This paper discusses GHGSat’s pioneering operating satellites dedicated to high-resolution measurements of methane emissions. We demonstrate their role as an integral part of an emissions intensity improvement strategy. The instrument on board each satellite uses spectroscopy principles to detect and quantify methane emissions, exhibiting a spatial resolution of less than 30 m. A discussion on how this constellation can be used as a key system in the mitigation of emissions is presented. Results reflect observations taken with GHGSat’s satellites. Recent examples of oil and gas emitting facilities around the world are shown followed by how this constellation can serve three objectives: (1) emissions mitigation; (2) regulatory compliance; and (3) a system to achieve voluntary efforts such as OGMP 2.0. The intention is to show that there isn’t a one-size-fits-all solution, but that the use of a satellite constellation is a complimentary and efficient way of monitoring for large leaks with increased frequency. This paper also reviews GHGSat’s top-down approach through its aircraft sensor technology as another solution for monitoring smaller leaks. Mitigation success stories are discussed providing opportunities for achievement of regulatory certifications in regions like the United States, Australia and Iraq. The resulting datasets are integrated into GHGSat’s ESRI ArcGIS-based portal, SPECTRA, to facilitate the interpretation of its high-resolution measurements, giving further insights through the available analytics layers. This platform provides situational awareness of methane emissions to operators, creating opportunities for mitigation. To access the Visual Presentation click the link on the right. To read the full paper click here
Emission Reductions Visual Presentation R02: Emissions, carbon abatement and data integration: CCS projects
Authors: Finnie Stephen
Published: June 2024

Emission Reductions Visual Presentation R02 The impacts of climate change and efforts to achieve net zero emissions underscore the importance of a varied range of technologies designed to decrease emissions and handle carbon effectively. As carbon capture and storage (CCS) projects become increasingly integral to decarbonisation efforts, complexities emerge in the management of operations, verification and monitoring, commercial, joint venture (JV) and regulatory requirements. External tools developed in Excel have been commonly used to carry out CCS related calculations, such as greenhouse gas (GHG) emissions, carbon credit units, and their allocation between JV participants, as well as generate reports. This approach can prove to have negative long-term impacts as it is difficult to maintain and can lack transparency and auditability, especially when poorly documented. In this paper, we explore how integrating a CCS application into the existing Data Management System (EnergySys), used for production allocation and GHG emissions reporting, can enhance operational efficiency and ensure adherence to both legislative and commercial standards in a transparent and auditable manner. To access the Visual Presentation click the link on the right. To read the full paper click here
Geoscience Visual Presentation G11: From raw seismic data to quantitative interpretation via cloud-based FWI
Authors: Debens Henry A.
Published: June 2024

Geoscience Visual Presentation G11 Full-waveform inversion (FWI) has evolved in recent years from a technique for recovering long- to intermediate-wavelength updates of acoustic overburden velocities as part of a broader model building workflow to a standalone tool for high-fidelity seismic imaging using raw seismic data – with ever greater resolution and ever more sophisticated physics being sought. In doing so, it has moved notably closer to fulfilling the vision of its original inventors in the late 70s and early 80s. In this work, two novel approaches to FWI along with enabling technologies for their effective deployment are considered. The first of these allows for robust long-wavelength updates to be generated from raw seismic data in the absence of diving wave energy, providing reliable estimates of acoustic velocity at depths equivalent to or greater than the longest offsets available in the data – thereby enabling more effective imaging with data of limited quality. The second allows for the estimation of elastic amplitude-versus-angle behaviour while still using an acoustic wave equation, thereby mitigating the significant computational burden typically associated with elastic FWI. Finally, it is demonstrated that these approaches can be deployed in a reliable and cost-effective manner via the considered use of public cloud resources, with learnings relevant for analogous massively parallel scientific applications. Case studies from two marine environments are provided for discussion, one being from deep-water US Gulf of Mexico and the other from intermediate water depths offshore Western Australia. To access the Visual Presentation click the link on the right. To read the full paper click here
Geoscience Visual Presentation G07: Thermochronological constraints on the tectonic history of the Polda Basin
Authors: Holford Simon
Published: June 2024

Geoscience Visual Presentation G07 The Polda Basin is a narrow, east–west striking intracontinental basin that extends ~400 km from the onshore Eyre Peninsula in South Australia to the offshore Great Australian Bight and contains up to 5 km of strata, with a thick sequence of Neoproterozoic rocks overlain by unconformably-bound sequences of Carboniferous-Permian, Jurassic and Cenozoic strata. Though the Polda Basin has witnessed limited exploration for hydrocarbons, it is attracting renewed interest due to the potential for underground hydrogen storage in Neoproterozoic halites, whilst surrounding regions of the Gawler Craton are considered prospective for natural hydrogen. To date however, knowledge of the tectonic history of the Polda Basin, which is critical to assessing its potential role in the energy transition, is limited. Here we present results from a regional apatite fission track analysis study of the Eyre Peninsula, focussing on data from the onshore Kilroo-1A borehole, which provide insights into the burial and exhumation history of the Polda Basin. Results indicate that the preserved Upper Jurassic sequence was thicker prior to Late Cretaceous exhumation, which may have supplied sediment to the adjacent Ceduna Sub-basin. Our results highlight a complex history of Phanerozoic vertical motions in this region, which have implications for both resource and energy storage potential. To access the Visual Presentation click the link on the right. To read the full paper click here
Geoscience Visual Presentation G01: A speculative ridge within the Kidson Sub-basin – integrated interpretation from geophysical data
Authors: Zhan Y.
Published: June 2024

Geoscience Visual Presentation G01 This paper presents an analysis of the basement geometry and its implications on the Kidson Sub-basin in the southern Canning Basin. Integration of seismic data primarily near the rim of the sub-basin with airborne electromagnetic data across its central portion reveals an east-northeast oriented ridge at Permian level, suggesting a possible elevated structure in the Ordovician and basement. The proposed ridge effectively separates the Kidson Sub-basin into two distinct parts, providing an explanation for facies and thickness variations observed in the Nambeet and Goldwyer formations, as well as the absence of the Willara Formation in the southeastern portion of the sub-basin. The presence of shallowing trends observed in seismic profiles along the southern flank of the ridge suggests the proximity of the basement high. The ridge is speculative and requires further work to verify its existence, potentially including passive and reflection seismic surveys across the structure. If confirmed, it might be a significant feature with far-reaching implications for the prospectivity of resources in the Kidson Sub-basin. The hydrocarbon sourced from the Nambeet, Goldwyer and Bongabinni formations in the NNW depocentre may have migrated via the extension of the Parallel Range Fault and be trapped in the footwall block over the ridge. Compared to the structures in the Fitzroy Trough, the traps within the Kidson Sub-basin are expected to maintain reasonable integrity and have good potential for petroleum accumulation and carbon sequestration in the thick Paleozoic succession. To access the Visual Presentation click the link on the right. To read the full paper click here
Geoscience Visual Presentation G05: The central and southeast offshore Otway Basin well folio
Authors: Nicholson Chris
Published: June 2024

Geoscience Visual Presentation G05 Geoscience Australia (GA) has produced a folio of 32 wells across the central and southeast regions of the Otway Basin. This folio covers the areas from Normanby 1 on the Normanby Terrace, through the Shipwreck Trough and Nelson Sub-basin, to Whelk 1 in the southeast. Composite logs for each well in the folio include wireline logs, petrophysical analysis, interpreted lithology, organic geochemical data, organic petrology data, and sequence stratigraphic markers. This folio also includes core-based depositional environment (DE) and gross depositional environment (GDE) interval interpretations which were used to constrain wireline interpretation of DE/GDE away from core control. The folio includes the digital data package used to construct each well composite. The new folio complements a recently published folio of northeast offshore Otway Basin wells, with both designed as resources to support exploration in the offshore Otway Basin. To access the Visual Presentation click the link on the right. To read the full paper click here
Health, Safety and Environment Visual Presentation H06: Changes in well control training to meet the challenge of reducing well control incidents
Authors: Sehnal Zdenek
Published: June 2024

Health, Safety and Environment Visual Presentation H06 The number of safety related incidents in the Oil and Gas industry has steadily declined over the past 20 years. However, the frequency of well control incidents has not followed the same trend. The Norwegian regulator (Petroleum Safety Authority) has recently documented this finding as related to the Norwegian sector of the North Sea. Globally, the International Association of Oil and Gas Producers (IOGP) Report 637 and recent data from Wild Well Control also support this conclusion – in fact, Wild Well Control data shows that the frequency of well control incidents may be increasing. The loss of experienced personnel due to reduced activity during the COVID-19 pandemic may have contributed to this. Now that activity is increasing again, the industry faces a challenge in recruiting skilled personnel. Current well control courses predominantly cover the well construction process, with minor emphasis on the whole life cycle of the well. However, a significant number (in some areas close to half) of well control incidents occur after the well construction process is completed. Based on analysis of the main contributory factors to well control incidents, IOGP has recently updated Report 476 ‘Recommendations for enhancements to well control training, examination and certification’. This paper reviews the changes to Report 476 and discusses how International Well Control Forum can contribute to reduce the well control incident rate with focus on the Well Control in Design and Lifecycle Management course. To access the Visual Presentation click the link on the right. To read the full paper click here
Session 23. Oral Presentation for: Innovation and opportunity through regulatory change
Authors: McCarrey Sue
Published: June 2024

Presented on Wednesday 22 May: Session 23 Adapting to change and seizing opportunities is a constant process for all involved in offshore energy, government and industry alike. The offshore energy sector continues to adapt approaches and adopt new ways of doing business as community expectations and the regulatory framework continue to evolve. As industry explores new frontiers in carbon capture and storage and infrastructure reuse for renewables, the historic challenges of legacy wells and decommissioning remain at the forefront of planning considerations. Recognising this changing landscape, the regulator has undergone its own evolution from investigations to drive change and enhance safety standards through to consultation best practice based on cultural awareness. This change has been driven by a refocusing of priorities and increased emphasis on where the greatest regulatory impact can be achieved. This paper outlines critical learnings from the past year – what industry is doing well and ongoing opportunities for improvement, the changes being implemented by the regulator and what they mean for industry, and what lies ahead for the offshore sector in the broader legislative and regulatory regime. To access the Oral Presentation click the link on the right. To read the full paper click here
Nonequilibrium hyperuniform states in active turbulence
Authors: Backofen Rainer , Altawil Abdelrahman Y. A. , Salvalaglio Marco , Voigt Axel
Published: June 2024

We demonstrate that the complex spatiotemporal structure in active fluids can feature characteristics of hyperuniformity. Using a hydrodynamic model, we show that the transition from hyperuniformity to nonhyperuniformity and antihyperuniformity depends on the strength of active forcing and can be related to features of active turbulence without and with scaling characteristics of inertial turbulence. Combined with identified signatures of Levy walks and nonuniversal diffusion in these systems, this allows for a biological interpretation and the speculation of nonequilibrium hyperuniform states in active fluids as optimal states with respect to robustness and strategies of evasion and foraging.
Interface charge accumulation in bi-layer dielectrics between cable and accessory insulation under temperature gradient
Authors: Zhou Yifan , Jiang Bingxia , Dissado L A , Wang Wei , Jin Yuzhi , He Jinliang
Published: June 2024

Bi-layer dielectrics are a feature of high-voltage direct-current cable and accessory systems, giving rise to the interfaces between the cable and accessory insulation. The interfaces act as preference sites for space charge build-up and are therefore regarded as potential breakdown initiation sites. A further complication is that during the operation of cable, a temperature gradient (TG) will be produced across the bi-layer insulation. In this paper, carbon black (CB) nanoparticles with 0, 0.5, 1, 1.5, 3.5 and 5.5 wt% are doped into silicon rubber (SR), space charge distributions in bi-layer dielectrics composed of cross-linked polyethylene (XLPE) and CB/SR nanocomposites under DC voltage and TG are measured using the pulsed electroacoustic method, and the effects of the doping proportion of CB nanoparticles and the TG on the bi-layer interface charge behavior are investigated. The experimental results show that under the TG, CB nanoparticles doped into SR can effectively suppress the interface charge accumulation, the amount of the interface charge decreases with the increase of the doping proportion from 0 to 1.5 wt% but increases with the increase of the doping proportion from 1.5 to 5.5 wt%, and the CB nanoparticle with 1.5 wt% shows relatively better suppression effect on the interface charge accumulation. With the increase of the TG, the amount of the interface charge increases initially and then decreases.
The physics of nerf guns
Authors: Hughes Stephen
Published: June 2024

A class activity is described that involves taking a video of a nerf gun fired vertically. The ascension time of the nerf bullet is found by counting the number of video frames, which is then used to calculate the maximum height reached. The kinematic equations can then be used to calculate several extra pieces of information about the trajectory of the nerf bullet such as the initial velocity and the spring constant of the nerf gun, etc.
Evaluation of radiation shielding performance: comparison of lead and polyvinylidene difluoride reinforced with tungsten
Authors: Yazdankish Enayatolah
Published: June 2024

This study examines the shielding properties of polyvinylidene difluoride reinforced with 20%, 40%, and 60% weight fractions of tungsten and compares the findings to those obtained from lead. The mass and linear attenuation coefficient, half-value layer, and effective atomic number were calculated using the Phy-X/PSD software. From the photon interactions with matter point of view, the Photoelectric effect dominates in low-energy photons, while pair production is dominant in high-energy photons; meanwhile, Compton scattering remains almost constant across the energy range. The results show that the mass attenuation coefficient is higher for low-energy photons, and composites with a higher weight fraction of tungsten exhibit higher values of mass attenuation coefficients. The half-value layer decreased as the weight fraction of tungsten increased, and the effective atomic number was higher for lower energy photons. These findings were contrasted against calculations derived for lead. Within the energy interval of 20–200 keV, the mass attenuation coefficient for lead was observed to be approximately two times that of the optimal values recorded for the specific composites under examination, whereas at 2 MeV, this discrepancy diminished. The minimum half-value layer for polyvinylidene difluoride augmented with 60% weight proportions of tungsten in comparison to lead was identified at an energy of 2 MeV. During this interval, the half-value layer for this composite material was threefold greater than that of lead. Although the mass attenuation coefficient is higher for lead, in some energy ranges (about two MeV), the findings from the selected composites are completely comparable to those from lead, demonstrating the ability and performance of the polyvinylidene difluoride composites for radiation shielding.
Riemann-Hilbert approach and multi-soliton solutions of nonlocal Newell-type long wave-short wave equation
Authors: Li Wenjing , Zhang Yi , Yang Xiaolin
Published: June 2024

This article’s purpose is to investigate the inverse scattering transform of the nonlocal long wave-short wave (LW-SW) equation and its multi-soliton solutions via Riemann-Hilbert (RH) approach. By using spectral analysis to the Lax pair of LW-SW equation, the RH problem can be constructed. However, we consider spectral analysis from the time part rather than the usual space part, since it is hard to obtain the analyticity of the space part. Then the RH problem can be solved and the formula of the soliton solutions can be given. We provide several special soliton solutions including Y-shaped solitons, V-shaped solitons, bound-state solitons and mixed four-soliton solutions. Compared with the local case, the solutions of nonlocal LW-SW equation exhibit distinct characteristics that (i) these soliton solutions are strictly symmetric with respect to x = 0 under special parameter conditions, (ii) the mixed four-soliton solution, which combines Y-type and bound-state solitons, is novel.
Dynamic climbing behavior and self-extinction mechanism of DC arc in a gradually changed air gap
Authors: Guan Ruiyang , Yang Lixin , Yin Renhao , Pei Zhen , Li Sicong
Published: June 2024

DC arc behavior is normally a complicated and rapid time-dependent evolution process. To investigate the climbing behavior, dynamic properties, as well as the self-extinction mechanism, an experimental platform in collaboration with a pair of Jacob’s ladder electrodes was established. The overall evolution process including arc generation, arc combustion, and arc self-extinction was well accomplished. The dynamic climbing behavior and dynamic emission spectrum were captured. The dynamic volt-ampere characteristic, excitation temperature and electron density were all analyzed during the overall evolution process. Furthermore, the self-extinction mechanism under the function of Jacob’s ladder electrodes was explored. The experimental observations show that a two-stage climbing behavior is performed in succession. The dynamic resistance is fluctuated significantly in purple arc stage, while it is stable in yellow arc stage. The excitation temperature is positively correlated with arc current, but not strictly linear. The co-action results of two dynamic features make it more favorable for quick separation from the external ability of power supply. As a result, the arc is transitioned from self-sustaining state to non-self-sustaining state. This paper is regarded as a preliminary research aiming to provide some references for dynamic properties and self-extinction mechanism of the climbing arc in arcing horn.
On the foundations of the maximum entropy principle using Fenchel duality for Shannon and Tsallis entropies
Authors: Maréchal Pierre , Navarrete Yasmín , Davis Sergio
Published: June 2024

In this work, we address two main objectives. The first one is to provide a rigorous foundation to the maximum entropy principle in statistical physics, by making use of the Fenchel-Rockafellar duality. The second objective is to discuss the well-foundedness of the so-called escort distributions in the context of non-extensive entropy maximization. The duality treatment of maximum entropy confirms the non-rigorous results obtained via the usual variational calculus, however, the use of escort distributions yields undefined behavior when used consistently, and only leads to the desired results when used in an ad-hoc manner.
Highly accurate ab initio electronic stopping power results for protons in Al material: a Lindhard stopping theory investigation
Authors: Shukri Abdullah Atef , Al Shorman MM
Published: June 2024

The main goal of this work is to enhance theoretical precision evaluations for the random electronic stopping power (RESP) of protons in solid targets across a wide range of energies, including low, intermediate, and high energies. The RESP of protons is investigated in different crystalline forms of Al material: FCC and two theoretical build structures (hexagonal and tetragonal). Initially, we divide the RESP calculations of protons in Al material into two individual contributions: one for the valence electrons and the other for the core electrons. Using this approach, we introduce a combination method that defines the total RESP as the sum of these contributions. We estimate the core electrons’ contribution to the RESP results within the local density approximation (LDA) based on the Lindhard stopping theory, where we calculate the density of Al material within the density functional theory (DFT) framework. We employ the RESP contribution of valence electrons as determined in our previous study within the linear response time-dependent density functional theory. We produce high-quality RESP results with the assistance of the combination method with low computational cost compared to other theoretical works. We test the accuracy of using the LDA based on Lindhard’s stopping model in calculating the RESP of protons in the Al target. In addition, within this approach, we investigate the influence of the crystal structure on core electrons’ contribution to the RESP.
Optimization of foreground moment deprojection for semi-blind CMB polarization reconstruction
Authors: Carones A. , Remazeilles M.
Published: June 2024

Upcoming Cosmic Microwave Background (CMB) experiments, aimed at measuring primordial CMB polarization B-modes, require exquisite control of instrumental systematics and Galactic foreground contamination. Blind minimum-variance techniques, like the Needlet Internal Linear Combination (NILC), have proven effective in reconstructing the CMB polarization signal and mitigating foregrounds and systematics across diverse sky models without suffering from foreground mismodelling errors. Still, residual foreground contamination from NILC may bias the recovered CMB polarization at large angular scales when confronted with the most complex foreground scenarios.
By adding constraints to NILC to deproject statistical moments of the Galactic emission, the Constrained Moment ILC (cMILC) method has been demonstrated to further enhance foreground subtraction, albeit with an associated increase in overall noise variance. Faced with this trade-off between foreground bias reduction and overall variance minimization, there is still no recipe on which moments to deproject and which are better suited for blind variance minimization. To address this, we introduce the optimized cMILC (ocMILC) pipeline, which performs full automated optimization of the required number and set of foreground moments to deproject, pivot parameter values, and deprojection coefficients across the sky and angular scales, depending on the actual sky complexity, available frequency coverage, and experiment sensitivity. The optimal number of moments for deprojection, before paying significant noise penalty, is determined through a data diagnosis inspired by the Generalized NILC (GNILC) method.
Validated on B-mode simulations of the PICO space mission concept with four challenging foreground models, ocMILC exhibits lower Galactic foreground contamination compared to NILC and cMILC at all angular scales, with limited noise penalty. This multi-layer optimization enables the ocMILC pipeline to achieve unbiased posteriors of the tensor-to-scalar ratio, regardless of foreground complexity.
Probing the cosmological principle using the slope of log N-log S relationship for quasars
Authors: Panwar Mohit , Jain Pankaj
Published: June 2024

We study the dipole signal in the slope x of the log N–log S relationship for quasars using the CatWISE2020 catalog of infrared sources. Here N is the number of sources with flux density greater than S. The slope is extracted by using a maximized log-likelihood method as well as Bayesian analysis. We obtain the value x = 1.579 ± 0.001 for a quasar sample of 1355352 sources. We extract the dipole signal in this parameter by employing χ
2 minimization, assuming a sky model of x up to the quadrupole term. We find that the dipole amplitude |D| is 0.005 ± 0.002 and dipole direction (l, b) in Galactic coordinate system equal to (201.50° ± 27.87°, -29.37° ± 19.86°). The direction of dipole anisotropy is found to be very close to the hemispherical power asymmetry (l, b)=(221°,-27°) in the Cosmic Microwave Background (CMB). The dipole signal is also extracted using Bayesian analysis and found to be in good agreement with that obtained using χ
2 minimization. We also obtain a signal of quadrupole anisotropy which is found to be correlated with the ecliptic poles and can be attributed to ecliptic bias.
Complete analysis of hyperentangled Bell state in three degrees of freedom using Kerr effect and self-assisted mechanism
Authors: Zeng Zhi
Published: June 2024

We present an efficient scheme for the complete hyperentangled Bell state analysis (HBSA) of photon system with polarization and two longitudinal momentum degrees of freedom (DOFs), resorting to weak cross-Kerr nonlinearity, linear optical elements and single photon detectors. In the process of distinguishing the 64 hyperentangled Bell states in three DOFs, the self-assisted mechanism is embedded, which makes our scheme simple and realizable. Moreover, we have discussed the applications of this complete HBSA scheme for high-capacity quantum communication protocols that are based on photonic hyperentanglement in three DOFs.
Landau quantization effects on damping Kawahara solitons in electron–positron–ion plasma in rotating ionized medium
Authors: El-Awady E I , Hussain S , Akhtar N
Published: June 2024

For the dynamics of three-dimensional electron–positron–ion plasmas, a fluid quantum hydrodynamic model is proposed by considering Landau quantization effects in dense plasma. Ion–neutral collisions in the presence of the Coriolis force are also considered. The application of the reductive perturbation technique produces a wave evolution equation represented by a damped Korteweg–de Vries equation. This equation, however, is insufficient for describing waves in our system at very low dispersion coefficients. As a result, we considered the highest-order perturbation, which resulted in the damped Kawahara equation. The effects of the magnetic field, Landau quantization, the ratio of positron density to electron density, the ratio of positron density to ion density, and the direction cosine on linear dispersion laws as well as soliton and conoidal solutions of the damped Kawahara equation are explored. The understanding from this research can contribute to the broader field of astrophysics and aid in the interpretation of observational data from white dwarfs.
Non-perturbative dynamics of flat-band systems with correlated disorder
Authors: Li 李 Qi 骐 , Liu 刘 Junfeng 军丰 , Liu 刘 Ke 克 , Hu 胡 Zi-Xiang 自翔 , Li 李 Zhou 舟
Published: June 2024

We develop a numerical method for the time evolution of Gaussian wave packets on flat-band lattices in the presence of correlated disorder. To achieve this, we introduce a method to generate random on-site energies with prescribed correlations. We verify this method with a one-dimensional (1D) cross-stitch model, and find good agreement with analytical results obtained from the disorder-dressed evolution equations. This allows us to reproduce previous findings, that disorder can mobilize 1D flat-band states which would otherwise remain localized. As explained by the corresponding disorder-dressed evolution equations, such mobilization requires an asymmetric disorder-induced coupling to dispersive bands, a condition that is generically not fulfilled when the flat-band is resonant with the dispersive bands at a Dirac point-like crossing. We exemplify this with the 1D Lieb lattice. While analytical expressions are not available for the two-dimensional (2D) system due to its complexity, we extend the numerical method to the 2D α–T
3 model, and find that the initial flat-band wave packet preserves its localization when α = 0, regardless of disorder and intersections. However, when α ≠ 0, the wave packet shifts in real space. We interpret this as a Berry phase controlled, disorder-induced wave-packet mobilization. In addition, we present density functional theory calculations of candidate materials, specifically Hg1–x
Cd
x
Te. The flat-band emerges near the Γ point (k = 0) in the Brillouin zone.
Phase structure evolution and its effect on magnetic and mechanical properties of B-doped Sm2Co17-type magnets with high Fe content
Authors: Li 李 Yao-Wen 耀文 , Liu 刘 Zhuang 壮 , Wu 吴 Hai-Chen 海辰 , Wang 王 Fang 芳 , Zhu 竺 Chao-Qun 超群 , Tan 谭 Dong-Liang 栋梁 , Liu 刘 Yu 宇 , Yang 羊 Yang 杨 , Zhang 张 Ming-Xiao 明晓 , Chen 陈 Ren-Jie 仁杰 , Yan 闫 A-Ru 阿儒
Published: June 2024

The unique cellular microstructure of Fe-rich Sm2Co17-type permanent magnets is closely associated with the structure of the solid solution precursor. We investigate the phase structure, magnetic properties, and mechanical behavior of B-doped Sm2Co17-type magnets with high Fe content. The doped B atoms can diffuse into the interstitial vacancy, resulting in lattice expansion and promote the homogenization of the phase organizational structure during the solid solution treatment in theory. However, the resulting second phase plays a dominant role to result in more microtwin structures and highly ordered 2 : 17R phases in the solid solution stage, which inhibits the ordering transformation of 1 : 7H phase during aging and affects the generation of the cellular structure, and to result in a decrease in magnetic properties, yet the interface formed between it and the matrix phase hinders the movement of dislocations and enhances the mechanical properties. Hence, the precipitation of high flexural strain grain boundary phase induced by B element doping is also a new and effective way to improve the flexural strain of Sm2Co17-type magnets. Our study provides a new understanding of the phase structure evolution and its effect on the magnetic and mechanical properties of Sm2Co17-type magnets with high Fe content.
Two-dimensional Cr2Cl3S3 Janus magnetic semiconductor with large magnetic exchange interaction and high-TC
Authors: Fu 伏 Lei 磊 , Li 李 Shasha 沙沙 , Bo 薄 Xiangyan 祥 , Ma 马 Sai 赛 , Li 李 Feng 峰 , Pu 普 Yong 勇
Published: June 2024

The two-dimensional (2D) Janus monolayers are promising in spintronic device application due to their enhanced magnetic couplings and Curie temperatures. Van der Waals CrCl3 monolayer has been experimentally proved to have an in-plane magnetic easy axis and a low Curie temperature of 17 K, which will limit its application in spintronic devices. In this work, we propose a new Janus monolayer Cr2Cl3S3 based on the first principles calculations. The phonon dispersion and elastic constants confirm that Janus monolayer Cr2Cl3S3 is dynamically and mechanically stable. Our Monte Carlo simulation results based on magnetic exchange constants reveal that Janus monolayer Cr2Cl3S3 is an intrinsic ferromagnetic semiconductor with T
C of 180 K, which is much higher than that of CrCl3 due to the enhanced ferromagnetic coupling caused by S substitution. Moreover, the magnetic easy axis of Janus Cr2Cl3S3 can be tuned to the perpendicular direction with a large magnetic anisotropy energy (MAE) of 142 μeV/Cr. Furthermore, the effect of biaxial strain on the magnetic property of Janus monolayer Cr2Cl3S3 is evaluated. It is found that the Curie temperature is more robust under tensile strain. This work indicates that the Janus monolayer Cr2Cl3S3 presents increased Curie temperature and out-of-plane magnetic easy axis, suggesting greater application potential in 2D spintronic devices.
An auto-segmented multi-time window dual-scale neural network for brain-computer interfaces based on event-related potentials
Authors: Zhao Xueqing , Xu Ren , Xu Ruitian , Wang Xingyu , Cichocki Andrzej , Jin Jing
Published: June 2024

Objective. Event-related potentials (ERPs) are cerebral responses to cognitive processes, also referred to as cognitive potentials. Accurately decoding ERPs can help to advance research on brain-computer interfaces (BCIs). The spatial pattern of ERP varies with time. In recent years, convolutional neural networks (CNNs) have shown promising results in electroencephalography (EEG) classification, specifically for ERP-based BCIs. Approach. This study proposes an auto-segmented multi-time window dual-scale neural network (AWDSNet). The combination of a multi-window design and a lightweight base network gives AWDSNet good performance at an acceptable cost of computing. For each individual, we create a time window set by calculating the correlation of signed R-squared values, which enables us to determine the length and number of windows automatically. The signal data are segmented based on the obtained window sets in sub-plus-global mode. Then, the multi-window data are fed into a dual-scale CNN model, where the sizes of the convolution kernels are determined by the window sizes. The use of dual-scale spatiotemporal convolution focuses on feature details while also having a large enough receptive length, and the grouping parallelism undermines the increase in the number of parameters that come with dual scaling. Main results. We evaluated the performance of AWDSNet on a public dataset and a self-collected dataset. A comparison was made with four popular methods including EEGNet, DeepConvNet, EEG-Inception, and PPNN. The experimental results show that AWDSNet has excellent classification performance with acceptable computational complexity. Significance. These results indicate that AWDSNet has great potential for applications in ERP decoding.