bluuebunny/crossref_metadata_2025 huggingface dataset:
Petrophysical characterisation of the Neoproterozoic and Cambrian successions in the Officer Basin
Authors: Wang Liuqi , Bailey Adam H. E. , Carr Lidena K. , Edwards Dianne S. , Khider Kamal , Anderson Jade , Boreham Christopher J. , Southby Chris , Dewhurst David N. , Esteban Lionel , Munday Stuart , Henson Paul A.
Published: May 2022

The Neoproterozoic–Paleozoic Officer Basin, located in South Australia and Western Australia, remains a frontier basin for energy exploration, with significant uncertainty due to a paucity of data. As part of Geoscience Australia’s Exploring for the Future (EFTF) program, the objective of this study is to derive the petrophysical properties and to characterise potential reservoirs in the Neoproterozoic–Cambrian sedimentary succession in the Officer Basin through laboratory testing and well log interpretation using both conventional and neural network methods. Laboratory measurements of 41 legacy core samples provide the relationships between gas permeability, Klinkenberg corrected permeability, and nano-scale permeability, as well as grain density, effective and total porosity for various rock types. Conventional log interpretation generates the volume fraction of shale, effective and total porosity from gamma ray and lithology logs. A self-organising map (SOM) was used to cluster the well log data to generate petrophysical group/class index and probability profiles for different classes. Neural network technology was employed to approximate porosity and permeability from logs, conventional interpretation results and class index from SOM modelling. The Neoproterozoic−Cambrian successions have the potential to host both conventional and tight hydrocarbon reservoirs. Neoproterozoic successions are demonstrated to host mainly tight reservoirs with the range in average porosity and geometric mean permeability of 4.77–6.39% and 0.00087–0.01307 mD, respectively, in the different sequences. The range in average porosity and geometric mean permeability of the potential Cambrian conventional reservoirs is 14.54−26.38% and 0.341−103.68 mD, respectively. The Neoproterozoic shales have favourable sealing capacities. This work updates the knowledge of rock properties to further the evaluation of the resource potential of the Officer Basin.
Optimising value in the mature Turrum Field: integrating modern seismic, high-resolution sequence stratigraphy and production data in a 3D geological model
Authors: Debenham Natalie , Fynnaart Adam , Ryan Melanie , Goody Angus
Published: May 2022

The Turrum Field in the offshore Gippsland Basin has been a significant producing field since first development in 2004 and remains a keystone gas resource for the future as many of the Gippsland assets continue to deplete. The Turrum Field is a faulted anticlinal structure with multiple, stacked, Paleocene-aged fluvial to lagoonal reservoirs that stratigraphically sit below the overlying Marlin Field gas cap. This field was developed in two phases with drilling campaigns in 2004 and 2015 and includes a dedicated platform (Marlin B) for the higher pressure, higher CO2 gas. Leveraging the 2018 reprocessed Northern Margins 3D seismic survey with a modern broadband processing workflow and wider bandwidth and higher signal-to-noise ratio has led to a seismic image with greater resolution and allowed improved reservoir characterisation. The uplift in seismic data together with the colour blending capabilities in GeoTeric®, has led to the seismic identification of large-scale fluvial reservoir systems. These products have been integrated with a revised field-wide sequence stratigraphic framework, petrophysical analysis and incorporated into a full-field 3D geological model of the Turrum Field. The resultant geological model has improved our understanding of reservoir connectivity and will enable rapid integration of production and surveillance data to optimise gas deliverability. This will also provide increased confidence for future field depletion planning including the identification of potential bypassed gas opportunities prior to end of field life.
Well productivity trends in Queensland coal seam gas and the incremental well breakeven
Authors: Zeng Jimmy
Published: May 2022

Development of coal seam gas (CSG) in Queensland (QLD) for export as liquefied natural gas (LNG) and domestic pipeline gas over the past decade has been a major Australian energy sector story. During the ramp-up period in 2015, public attention was drawn to the potential impacts of exported gas on the overall supply/demand balance and pricing outcomes for the domestic gas market. An overarching expectation of a ‘supply shortfall’ in the domestic gas market even with the growth in CSG development has taken hold as a result. This paper examines the historical record in the CSG upstream, reviewing reserves, production levels, and providing an analysis of average well flowrates. Upcoming development projects are set within this context of observed declining average well performance, and a range of ex-field breakeven gas prices to incentivise the ‘incremental CSG well’ are discussed. Maintenance of per well costs at low levels is a key factor influencing the breakeven level of ‘brownfield’ development. The analysis concludes with a reiteration of the perceived importance of CSG development for meeting expected supply shortfalls in the domestic market. Upstream risks (reserves, well performance) over the next decade are unlikely to be the major influence on CSG’s relevance to the domestic market (i.e. development is not resource-constrained). Rather, customer willingness to pay current high prices are likely to provide the key demand constraint – notwithstanding the possibility of new CSG acreage being developed at lower breakevens.
West Barracouta – 50 years in the making
Authors: Chigwidden Daniel , Felgate Matthew
Published: May 2022

This paper presents a case study on the value of combining existing ideas with new data to evaluate and determine the most effective way to extend the producing life of one of the first offshore gas discoveries in the Gippsland Basin. The holistic work approach resulted in the development of West Barracouta Top Latrobe gas by two dual-zone, subsea intelligent wells with sand control, tied back to an operating pipeline to minimise brownfields interface. Located in the Gippsland Basin, the Barracouta gas field was Australia’s first discovery, by the first offshore well, and soon after the first operating offshore facility. After more than 50 years of oil and gas production, new data gives further insight to support continuous improvement in reservoir management to optimise the resource to end of field life. Originally discovered in 1969, West Barracouta is separated from the main field by a fault-induced saddle point that left a substantial volume without an active completion. With the Gippsland legacy gas fields declining, the West Barracouta development is well timed to supply the Australian East Coast gas market with one of the last remaining low-CO2 gas sources and ensure additional security of supply. Incorporating reprocessed seismic data into the workflow delivered improved confidence in field definition, providing a foundation for a technology-driven development plan. This paper addresses the technical workflow that was implemented to support a fast-paced subsea development, robust against the range of possible geological scenarios.
Unlocking Gippsland reserves with a minimum kit solution – West Barracouta
Authors: Kubik John , Shaw Grant , Vicario Melissa
Published: May 2022

The West Barracouta (BTW), field one of the largest proven undeveloped gas fields off the south-eastern Australian coast, commenced production in April 2021. The project was developed by Esso-BHP Gippsland Basin Joint Venture (JV), a 50–50 JV between ExxonMobil’s subsidiary Esso Australia and BHP Petroleum. The BTW gas field is situated ~6 km south west of the existing Barracouta gas field and platform, the first Gippsland Basin Joint Venture platform in Bass Strait. The BTW development involved drilling two subsea production wells, installation of umbilical controls from the existing platform and installation of a ~6 km subsea flowline to connect to existing gas pipeline via a hot tap. The BTW team will share insights on how it: (1) utilised minimum kit solution and verification of existing asset condition; subsea hot tap into operational gas pipeline and re-use of existing platform J-tube to minimise works on and around the Barracouta Platform (including diving work). (2) Managed an Operator first – co-mingled wet gas subsea pipelines while operating in hydrate regions; via detailed water detection metre/software solution, downhole zone isolation and systematic operating guidelines. (3) Leveraged Installation Contractor competitive Front End Engineering and Design (FEED) enabling optimisation of facilities design/execution strategies to align with strengths and maximise overall project value. (4) Leveraged the OneSubsea/Subsea 7 Subsea Integration Alliance and global worldwide network to execute the subsea design (including qualification), manufacture and installation. (5) Utilised the incumbent Engineering, Procurement and Construction (EPC) contractor to integrate the subsea and topsides control systems to support a single operation system linked to the existing to Distributed Control System (DCS).
Building collaborative capacity to address Australia’s growing decommissioning needs
Authors: Norman Francis G.
Published: May 2022

Australia and indeed the Asia-Pacific region is facing a significant decommissioning workload. Recent work by the Centre of Decommissioning Australia (CODA) puts Australia’s potential offshore decommissioning cost at around US$40 billion and Wood Mackenzie predicting the region’s decommissioning to be in excess of US$100 billion. CODA was established in 2021 to support the coordinated effort required across the entire Australian value chain to address this immense domestic workload safely and effectively. Building on the release of the 2021 liability report, CODA, in conjunction with a number of operators, has undertaken three additional studies, looking at: planning and execution global best practice applicable to Australian operations; a decommissioning technology roadmap, and; a recycling and disposal pathways report. Supported by these studies to understand the current state and needs of the Australian decommissioning industry, CODA’s primary focus is to build domestic capacity and capability. To this end CODA is working with operators, the service and supply sector, state and federal government, regulators and researchers to establish a collaborative network that can enhance the visibility of upcoming work, surface and support the growth of domestic capability and share best practice in decommissioning. This paper highlights findings from the new reports and shares insights into CODA’s ongoing work to build an inclusive Australian decommissioning community of practice ready to undertake the next decades of activity.
Hydrogen storage potential of depleted oil and gas fields in Western Australia
Authors: Craig Adam , Newman Stephen , Stephenson Peter , Evans Chris , Yancazos Shaun , Barber Simon
Published: May 2022

The global subsurface hydrogen storage industry is at an embryonic stage and is currently dominated by a handful of manufactured salt caverns worldwide. There are currently no known depleted oil or gas fields used to store pure hydrogen, although there are examples of hydrogen and natural gas mixtures. The Government of Western Australia has developed a renewable hydrogen strategy with a vision for Western Australia becoming a significant producer, exporter and user of renewable hydrogen. An element of the strategy and roadmap includes the possibility of utilising depleted oil and gas fields for transitory geological storage of hydrogen. The physical characteristics of hydrogen are quite different to natural gases and a number of potential loss mechanisms need to be considered for transitory geological storage. Currently, 30 renewable energy projects with associated hydrogen generation are proposed or being considered in Western Australia. It is assumed that some, if not all, of these projects may require transitory geological storage of hydrogen. An assessment of the required storage potential has been made and 23 onshore depleted oil and gas fields of the onshore northern Perth Basin and Carnarvon Basin were screened for their suitability to satisfy the storage requirements of a renewable hydrogen industry. Seven fields were then selected as suitable candidates for transitory hydrogen geological storage sites.
Carbon capture and storage: a review of Australian projects
Authors: Quinn Matthew
Published: May 2022

Within Australia, carbon capture and storage (CCS) and carbon capture, utilisation and storage will play a significant role as part of an ‘all of the above’ approach to managing greenhouse gas emissions. Two CCS projects are currently operating: Gorgon and the Otway CCS project. The Gorgon and Jansz-Io fields contain approximately 14% carbon dioxide (CO2). The CO2 is brought to shore at Barrow Island and injected into the Dupuy Formation saline aquifer at a depth of 2500 m. While the project has experienced delays with start-up and operational issues, to July 2021 nearly 5 MMt of CO2 had been injected. The Otway CCS Project is a research facility used to study subsurface CO2 storage and behaviour within saline aquifers and depleted reservoirs. Since the start of the project in 2007 a total of 95 000 t of CO2 has been stored. Final Investment Decision was taken for the Moomba CCS project on 1 November 2021 and for the Leigh Creek Urea project in March 2021. In addition, feasibility studies are being carried out across multiple projects within Australia including the South West and Mid-West Projects in the Perth Basin, CarbonNet in Victoria’s Latrobe Valley and Gippsland Basin and the Moonie oil field EOR, Integrated Surat Basin Project and the ATP 2062-P Buckland Basalt projects in the Bowen-Surat Basin. A CCS hub at Bayu-Undan is being assessed as a possible option to reduce the carbon footprint of the Barossa, Caldita and Evans Shoals projects, and feasibility studies are underway into large-scale multi-user CCS hubs near both Darwin and Karratha.
Industry-wide learnings from the independent review of Australia’s most complex decommissioning program
Authors: Gray Alasdair , Wilson Chris
Published: May 2022

In 2019, the Minister for Resources and Northern Australia issued a Statement of Expectations to the National Offshore Petroleum and Safety Environmental Management Authority (NOPSEMA) establishing heightened expectations for duty holder compliance with their decommissioning obligations. In response, NOPSEMA increased compliance monitoring and enforcement activities to assess adequacy of the level of decommissioning planning and implementation by duty holders. On 20 May 2021, NOPSEMA issued a general direction to Esso Australia relating to their Bass Strait decommissioning program, likely one of Australia’s most significant and complex decommissioning projects. The direction included a requirement to undertake an independent review of Esso’s engineering and project management approach and consider if there were opportunities for reducing the timeframe to commence and subsequently complete all necessary decommissioning activities. This review was subsequently awarded to Xodus, in partnership with Labrador and focussed on core disciplines such as project management, regulatory approvals, stakeholder engagement, well plugging and abandonment, contracting, topsides and subsea facilities and waste management. Australia is at a pivotal stage in the context of decommissioning oil and gas infrastructure. With heightened regulatory oversight alongside recent and continuing changes to legislation, ensuring supply chain is ready to deliver against this backdrop will be critical to the future success of regional decommissioning and ensure all parties bearing the cost of this work are satisfied. This paper will discuss the independent review process of Esso’s decommissioning program and outline key challenges and opportunities the industry faces in realising improved decommissioning efficiency in the region.
Strategies for actively engaging with Indigenous businesses
Authors: Williams Llewellyn , McCafferty Kevin
Published: May 2022

Indigenous businesses are significantly contributing to the Australian economy and the improved circumstances of Aboriginal and Torres Strait Islander peoples, their families and communities through social and economic empowerment. Supplier diversity has significant and measurable long-term business benefits. Diversity within supply chains can not only bring new ideas and solutions to an organisation, but also boost competitiveness and market growth. But it goes further than these commercial benefits to encompass social value; the ability to reduce socio-economic inequality and create stronger, more stable communities. In this case study, the authors demonstrate key strategies for actively engaging with Indigenous businesses resulting in an increased spend of A$83.9 million compared to A$54.9 million for the same period last year, representing a 54% year-on-year increase. These key strategies are: (1) Identify verified Indigenous businesses; (2) Align objectives and requirements with key stakeholders; (3) Start small and increase scope with capability; and (4) Make it easy for Indigenous businesses to engage with organisations. Realising the potential of Indigenous businesses will create a new generation of entrepreneurs who grow their own business knowledge, networks, assets and wealth, removing barriers to employment for future generations and helping create a positive cycle of social and economic empowerment. Case study: Indigenous Beverages Australia is a unique company run and owned by a Goreng Goreng heritage family. Initially supplying a range of quality natural spring water, beverage and specialty coffee products, the company is now one of Ventia’s largest Supply Nation-certified suppliers providing products including coffee cups, coffee beans and isotonic drinks throughout Australia.
Fish associated with subsea pipelines and their rock berms
Authors: van Elden Sean , Tothill Thomas , Meeuwig Jessica J.
Published: May 2022

The ecological role of subsea pipelines is an important factor in the consideration of decommissioning options. Several studies have assessed the marine communities associated with subsea pipelines on Australia’s North West Shelf (NWS), considering the influence of factors such as water depth, substrate type, pipeline diameter and pipeline position on fish assemblages. Less is known about the artificial rock berms used to stabilise pipelines. The Wandoo field on the NWS consists of an unmanned monopod and a concrete gravity structure, with three pipelines connecting these structures: a 4″ Gas Flowline, an 8″ Test Flowline and a 12″ Production Flowline. These pipelines are buried, exposed or span the seabed and are supported by rock berms at regular intervals. We present a novel frame-based, timed-count method to assess the fish communities associated with subsea pipelines utilising archival remotely operated vehicle footage that lacks geospatial data. We apply this approach to a pipeline in the Wandoo field to document variation in the fish assemblage with pipeline position (buried, exposed, span or covered by rock berm). Overall, diversity and abundance were higher on pipeline covered by rock berms than on the other pipeline positions. We hypothesise that rock berms are effectively artificial reefs, providing complex habitat structure and facilitating growth of macrobenthos communities that are associated with higher fish diversity. We demonstrate that rock berms can increase the ecological value of subsea pipelines and should therefore be a priority area for future ecological surveys.
INPEX-led Ichthys Joint Venture – developing a dynamic adjustment area to identify, time, duration and potential exposure periods related to a 2D seismic survey offshore Western Australia
Authors: Prout Jake , Miller Paul , O’Donoghue Shane
Published: May 2022

The oil and gas industry is striving for effective consultation between titleholders and commercial fishing stakeholders. Recent developments in cross-industry consultation have resulted in frameworks to provide an adjustment (compensation) claim process, where short-term displacement of fishers and reduction of catch coincident and following marine seismic survey activities may occur. 3D seismic surveys are undertaken more intensively, in geographically smaller areas and shorter time periods. This allows for discreet areas and periods to be defined for the applicability of a claim when fishing catch rates or displacement may occur. By contrast, 2D seismic surveys can be undertaken at regional scales with long sail line transects. These result in a survey vessel being active in an area of potential acoustic influence for infrequent and short periods of time, thus making justification for claims, for loss of catch or displacement, over the full survey area and full acquisition period challenging. To address this challenge a novel approach was developed to determine a dynamic area, based on where and when a survey vessel was operating the seismic source. INPEX utilised the 10 nautical miles (nm) × 10 nm geospatial grid data set provided by Department of Primary Industries Resources and Development, for commercial fishers to report catch effort. The methodology used modified navigation files, to determine the frequency, duration and number of times a fishing block was intersected during the survey. The resulting data provided an ‘adjustment area’ and ‘exposure date’ which could then be referred to as a basis for claim.
Net zero hero – five strategies for oil and gas producers
Authors: Farrell Bradley
Published: May 2022

In the last 12 months, Australian oil and gas producers have been busy announcing their ambition to become ‘net zero emissions’ businesses by 2050, or sooner. Achieving this will require a significant shift in strategy in how companies operate, and in what they produce. In pursuing these new net zero ambitions, we see five major strategies in play: reducing scope 1 and scope 2 emissions; deployment of carbon capture, utilisation and storage (CCUS) technologies; use of general and cargo-specific carbon offsets; pursuit of hydrogen production at scale; and displacing higher-emissions fuels in the global energy mix. This paper provides an overview and integrated programmatic approach to realise these strategies, including a case study from a recent global oil and gas producer.
APOBEC3A regulates transcription from interferon-stimulated response elements
Authors: Taura Manabu , Frank John A. , Takahashi Takehiro , Kong Yong , Kudo Eriko , Song Eric , Tokuyama Maria , Iwasaki Akiko
Published: May 2022

Significance

APOBEC3A (A3A) is a DNA binding enzyme that introduces mutations through its cytidine deaminase activity. In addition, A3A can repress proviral HIV-1 and retroelements within the host genome by a deaminase-independent mechanism. Here, we demonstrate that A3A binds to the promoter sequence of interferon (IFN)-stimulated gene (ISG)15 and suppresses IFN-stimulated response element activity. In a deaminase-independent manner, A3A reduces
ISG15
expression in response to IFN stimulation.
A3A
overexpression decreases and
A3A
knockout increases the expression of several ISGs in response to IFN-α treatment. Since
A3A
itself is an ISG, our data suggest that
A3A
plays a role in a negative feedback loop to control ISG expression.
Gaze following requires early visual experience
Authors: Zohary Ehud , Harari Daniel , Ullman Shimon , Ben-Zion Itay , Doron Ravid , Attias Sara , Porat Yuval , Sklar Asael Y. , Mckyton Ayelet
Published: May 2022

Significance

Early in life, humans spontaneously learn to extract complex visual information without external guidance. Current vision models fail to replicate such learning, relying instead on extensive supervision. A classic example is gaze understanding, an early-learned skill useful for joint attention and social interaction. We studied gaze understanding in children who recovered from early-onset near-complete blindness through late cataract surgery. Following treatment, they acquired sufficient visual acuity for detailed pattern recognition, but they failed to develop automatic gaze following. Our computational modeling suggests that their learning is severely limited due to reduced availability of internal self-supervision mechanisms, which guide learning in normal development. The results have implications to understanding natural visual learning, potential rehabilitation, and obtaining unsupervised learning in vision models.
Effects of anisotropy and pre-strain on the shear fatigue behaviour of DP600 steel
Authors: Zhang Zhongran , Yue Zhenming , Bao Yanmei , Gao Jun
Published: May 2022

The effects of anisotropy and pre-strain on the low-cycle-fatigue properties of DP600 steel sheet under shear path were investigated. Fully reversed strain-controlled fatigue tests were performed along the 0° and 90° directions with the initial strain direction. The cyclic-loading amplitude determined whether the pre-strained material had a hardening process. The high dislocation density in the crystals of pre-strained material can promote the formation of low-energy substructures, obviously accelerating the cyclic-softening rate and reducing the fatigue life. Average plastic strain energy density was affected by the pre-straining state and loading direction and had a linear relationship with the strain amplitude. Overall, these results can be used to verify the calculation model of structural parts.
Rotating hybrid stars with color-flavor-locked quark matter
Authors: Sen Debashree , Chaudhuri Gargi
Published: May 2022

In the present work we achieve phase transition from β stable hadronic matter to color-flavor locked (CFL) quark matter with Maxwell construction. The hybrid equation of state (EoS), obtained for different values of bag pressure B and gap parameter Δ, have been used to compute the speed of sound in hybrid star (HS) matter. The structural properties of HSs in both static and rotating conditions have been calculated in light of various constraints from different astrophysical and empirical perspectives. The effects of B and Δ on the EoS and structural properties have been investigated. At a certain density, shortly after phase transition, the HSs become unstable. In static conditions, the mass-radius solutions satisfy the constraints from GW190425, NICER experiment for PSR J0030+0451 and PSR J0740+6620 and from massive pulsars like PSR J0348+0432 and PSR J0740+6620. In rapidly rotating conditions at Kepler frequency, the constraints on maximum mass from the secondary component of GW190814 and that on rotational frequency from fast pulsars like PSR B1937+21 and PSR J1748−2446ad are all satisfied. In slowly rotating conditions, the universality relations in terms of normalized moment of inertia also hold quite well for most of our HS configurations.
Antenna designing for efficient rectenna solar cells
Authors: Muhibbullah M , Alhazime Ali A , Amin Muhammad , El-Zohary Salah E
Published: May 2022

The rectenna solar cell is considered to be one of the best photovoltaic devices due its effective light to electric energy conversion performance. New ideas are needed to improve the design of efficient rectenna solar cells. In this paper, we have described a novel design of an antenna associated with a rectifier. Solar spectrum contains radiation of different wavelengths and intensities. The intensity of solar radiation is maxima at around the 500 nm wavelength. The monopole antenna of the length 125 nm (dipole of the length 250 nm) converts the maximum energy of the solar spectrum. Metallic behaving nano rods may be better as the antenna. The carriers of the nano rod should remain free from any bias for highly efficient rectenna solar cells. The pn junction should be used as a rectifier in the rectenna solar cells to get better receiving power. The rectifier(s) position may keep a role to increase the receiving power. Furthermore, we proposed some important analytical investigations that could help to optimize the antenna carrier density.
Effect of manganese doping on the structural, mechanical, optical, and magnetic properties of zinc ferrite nanoparticles
Authors: Mahmood Aamir , Maqsood Asghari , Abdi Ahmed
Published: May 2022

The effects of manganese doping on the structural, mechanical, optical, and magnetic properties of zinc ferrite nanoparticles (

Zn

1
−
x

Mn

x

Fe

2

O

4

,

x = 0.00, 0.03, 0.06, 0.10) are reported. The variation in lattice parameters, average crystallite sizes, and the cation distribution of the mixed-spinel

Zn

1
−
x

Mn

x

Fe

2

O

4

NPs were noticed. The spherical morphologies and particle sizes were observed using scanning electron microscopy (SEM), and the elemental composition was found using energy dispersive x-ray (EDX) spectroscopy. The FT-IR spectra showed significant absorption bands, and the values of Debye temperature (θ
D) increased with the doping of Mn2+ content and an increase in the lattice vibrations. UV-visible diffuse reflectance spectroscopy (DRS) was used to find the optical energy bandgap values from 1.87 to 1.98 eV. The magnetic properties were evaluated using a vibrating sample magnetometer (VSM). Significant variations between the experimental and theoretical magnetic moments were observed, suggesting that the present system showed Yafet-Kittel type magnetic ordering.
Reionization process dependence of the ratio of CMB polarization power spectra at low-ℓ
Authors: Kitazawa Noriaki
Published: May 2022

We investigate
how much the ratio of cosmic microwave background (CMB) polarization power spectra CBB
ℓ
/CEE
ℓ
  at low-ℓ (ℓ ≲ 10) depends on the process of reionization.
Both such low-ℓ B-mode and E-mode polarization powers
are dominantly produced by Thomson scattering of CMB photons off the free electrons
which are produced in the process of reionization.
Since the reionization should be finished until at least the redshift z ≃ 6
and the low-ℓ polarization powers are produced at late time,
the ratio is rather insensitive by the ionization process at higher redshifts,
but it is sensitive to the value of optical depth.
The value of the ratio at ℓ = 2, however,
is almost insensitive to the reionization process including the value of optical depth,
and the value is approximately half of the value of tensor-to-scalar ratio.
This fact can be utilized for future determination of tensor-to-scalar ratio
in spite of the ambiguity due to cosmic variance.
Deciphering signatures of Bardeen black holes from the observed quasi-periodic oscillations
Authors: Banerjee Indrani
Published: May 2022

Quasi-periodic oscillations (QPOs) observed in the power spectrum of black holes are unique observational probes to the background spacetime since they can be directly related to the timescales associated with the motion of matter orbiting in the vicinity of the black hole horizon. In this regard, the high frequency QPOs (HFQPOs) are particularly interesting as they occur in commensurable pairs, the most common ratio being the 3:2 twin peak QPOs. The theoretical models which aim to explain these QPOs express the observed frequencies in terms of the epicyclic motion of test particles in a given background spacetime. In this work, we study the signatures of Bardeen spacetime from the observed QPOs in the black hole power spectrum. Bardeen black holes are rotating, regular black holes with a magnetic monopole charge. Such regular backgrounds are theoretically interesting as they can potentially evade the curvature singularity, otherwise unavoidable in general relativistic black holes. We perform a χ2 analysis by comparing the available observations of the quasi-periodic oscillations from black hole sources with the relevant theoretical models and note that the Kerr black holes in general relativity are observationally more favored compared to black holes with a monopole charge. Our analysis reveals that black holes with very high monopole charges are disfavored from QPO related observations.
New insight into the mechanism of DNA polymerase I revealed by single-molecule FRET studies of Klenow fragment
Authors: Parvin Rokshana , Jia Qi , Ma Jianbing , Xu Chunhua , Lu Ying , Ye Fangfu , Li Ming
Published: May 2022

We use single-molecule FRET and newly-developed D-loop techniques to investigate strand displacement activity of Klenow fragment (exo-) of DNA polymerase I in DNA sequences rich in guanine and cytosine (GC) bases. We find that there exist in the FRET traces numerous ascending jumps, which are induced by the backsliding of Klenow fragment on DNA chains. Our measurements show that the probability of backsliding is closely related to the GC-richness and dNTP concentration: increasing the GC-richness leads to an increase in the backsliding probability, and increasing the dNTP concentration however leads to a decrease in the backsliding probability. These results provide a new insight into the mechanism of DNA polymerase I.
Numerical simulation of the thermal non-equilibrium flow-field characteristics of a hypersonic Apollo-like vehicle
Authors: Yu Minghao , Qiu Zeyang , Lv Bo , Wang Zhe
Published: May 2022

In order to investigate the relationship between the flow-field parameters outside the vehicle and the altitude, this paper takes the Atmospheric Reentry Demonstrator (ARD) with an angle of attack of –20° as the research object and adopts a two-temperature model coupled with the shear-stress transport k–ω turbulence model to focus on the variation of flow-field parameters including flow-field pressure, Mach number and temperature with the reentry altitude. It is found that the flow-field high-pressure region and low-Mach region both appear in the shock layer near the head of the ARD, while the maximum pressure of the surface appears on the windward side of the ARD’s head with a toroidal distribution, and the numerical magnitude is inversely proportional to the radius of the torus. With fluid through the shoulder of the ARD flow expansion plays a dominant role, the airflow velocity increases, the Mach number of the windward side of the rear cone increases and the flow-field pressure and surface pressure rapidly decrease. When the fluid passes through the shock layer, the translational–rotation temperature will increase before the vibration–electron temperature, there is a thermal non-equilibrium effect and the two temperatures will rapidly decrease again when approaching the surface of the ARD due to the existence of temperature gradient. At the same time, both the windward side of the shoulder and the back cover of the ARD suffer from a large thermal load and require thermal protection.
Improvement of femtosecond SPPs imaging by two-color laser photoemission electron microscopy
Authors: Fu Chun-Lai , Zhao Zhen-Long , Ji Bo-Yu , Song Xiao-Wei , Lang Peng , Lin Jing-Quan
Published: May 2022

Clear imaging of surface plasmon polaritons (SPPs) is a prerequisite for SPPs-based applications. In this work, we demonstrate an improvement of near-field imaging of SPPs via directly comparing the visibility of the photoemission electron microscopy (PEEM) image of SPPs under one- and two-color laser excitation (also known as one- or two-color laser PEEM). By measuring the photoelectron yield and the contrast of the interference fringes of SPPs, we demonstrate that in addition to enhancing the photoemission yield, two-color laser PEEM can significantly improve the contrast between bright and dark fringes (nearly 4 times higher than that of one-color laser case). By recording the nonlinear order of the photoelectrons ejected from the bright and dark fringes, respectively, the underlying mechanism for the improved visibility is revealed. In addition, the influences of the polarization direction of 400-nm laser on the PEEM images of the SPPs with different wave vector directions are shown. These results can provide technical support for the development of SPPs-based communication devices and catalysis.
Performance of phase-matching quantum key distribution based on wavelength division multiplexing technology
Authors: Ma Haiqiang , Han Yanxin , Dou Tianqi , Li Pengyun
Published: May 2022

Quantum key distribution (QKD) generates information-theoretical secure keys between two parties based on the physical laws of quantum mechanics. The phase-matching (PM) QKD protocol allows the key rate to break the quantum channel secret key capacity limit without quantum repeaters, and the security of the protocol is demonstrated by using equivalent entanglement. In this paper, the wavelength division multiplexing (WDM) technique is applied to the PM-QKD protocol considering the effect of crosstalk noise on the secret key rate. The performance of PM-QKD protocol based on WDM with the influence of adjacent classical channels and Raman scattering is analyzed by numerical simulations to maximize the total secret key rate of the QKD, providing a reference for future implementations of QKD based on WDM techniques.
Spin transfer nano-oscillator based on synthetic antiferromagnetic skyrmion pair assisted by perpendicular fixed magnetic field
Authors: Ma Yun-Xu , Wang Jia-Ning , Zeng Zhao-Zhuo , Yuan Ying-Yue , Yang Jin-Xia , Liu Hui-Bo , Zhang Sen-Fu , Wang Jian-Bo , Jin Chen-Dong , Liu Qing-Fang
Published: May 2022

As a microwave generator, spin transfer nano-oscillator (STNO) based on skyrmion promises to become one of the next-generation spintronic devices. However, there still exist a few limitations to the practical applications. In this paper, we propose a new STNO based on synthetic antiferromagnetic (SAF) skyrmion pair assisted by a perpendicular fixed magnetic field. It is found that the oscillation frequency of this kind of STNO can reach up to 5.0 GHz, and the multiple oscillation peak with higher frequency can be realized under a fixed out-of-plane magnetic field. Further investigation shows that the skyrmion stability is improved by bilayer antiferromagnetic coupling, which guarantees the stability process of skyrmion under higher spin-polarized current density. Our results provide the alternative possibilities for designing new skyrmion-based STNO to further improve the oscillation frequency, and realize the output of multiple frequency microwave signal.
Effect of porous surface layer on wave propagation in elastic cylinder immersed in fluid
Authors: Su Na-Na , Han Qing-Bang , Shan Ming-Lei , Yin Cheng
Published: May 2022

To study the damage to an elastic cylinder immersed in fluid, a model of an elastic cylinder wrapped with a porous medium immersed in fluid is designed. This structure can both identify the properties of guided waves in a more practical model and address the relationship between the cylinder damage degree and the surface and surrounding medium. The principal motivation is to perform a detailed quantitative analysis of the longitudinal mode and flexural mode in an elastic cylinder wrapped with a porous medium immersed in fluid. The frequency equations for the propagation of waves are derived each for a pervious surface and an impervious surface by employing Biot theory. The influences of the various parameters of the porous medium wrapping layer on the phase velocity and attenuation are discussed. The results show that the influences of porosity on the dispersion curves of guided waves are much more significant than those of thickness, whereas the phase velocity is independent of the static permeability. There is an apparent “mode switching” between the two low-order modes. The characteristics of attenuation are in good agreement with the results from the dispersion curves. This work can support future studies for optimizing the theory on detecting the damage to cylinder or pipeline.
Majorana zero modes induced by skyrmion lattice
Authors: Jing Dong-Yang , Wang Huan-Yu , Guo Wen-Xiang , Liu Wu-Ming
Published: May 2022

One-dimensional s-wave superconductor with spin-orbit coupling is a platform for the realization of Majorana zero modes. The spin-exchange with the magnetic skyrmion lattice can induce spin-orbit coupling in a s-wave superconductor system and the effects are different from the constant spin–orbit coupling. The strength of the effective spin–orbit coupling as well as the rich topoloigcal phase diagram are directly connected to the radius of the skyrmion lattice R. We obtain the rich topological phase diagram of this system with different skyrmion lattice radii by numerically evaluating the spectrum of the system under the periodic boundary condition, and we also find the Majorana zero modes under the open boundary condition to verify the bulk–edge correspondence.
Dynamics of molecular alignment steered by a few-cycle terahertz laser pulse
Authors: Cheng Qi-Yuan , Song Yu-Zhi , Li Deng-Wang , Liu Zhi-Ping , Meng Qing-Tian
Published: May 2022

The field-free alignment of molecule ClCN is investigated by using a terahertz few-cycle pulse (THz FCP) based on the time-dependent density matrix theory. It is shown that a high degree of molecular alignment can be obtained by changing the matching number of the THz FCPs in the adiabatic regime and the non-adiabatic regime. The matching number can affect both the maximum value of the alignment and the time at which it is achieved. It is also found that a higher degree of alignment can be achieved by using the THz FCP at lower intensity and there exists an optimal threshold of molecular alignment with the increase of the field amplitude. Also found is the frequency sensitive region in which the degree of maximum alignment can be enhanced greatly by modulating the center frequencies of different THz FCPs. The investigation demonstrates that comparing with a THz single-cycle pulse, a better result of the field-free alignment can be created by a THz FCP at a constant rotational temperature of molecule.
Adaptive semi-empirical model for non-contact atomic force microscopy
Authors: Chen Xi , Tong Jun-Kai , Hu Zhi-Xin
Published: May 2022

Non-contact atomic force microscope is a powerful tool to investigate the surface topography with atomic resolution. Here we propose a new approach to estimate the interaction between its tips and samples, which combines a semi-empirical model with density functional theory (DFT) calculations. The generated frequency shift images are consistent with the experiment for mapping organic molecules using CuCO, Cu, CuCl, and CuO
x
tips. This approach achieves accuracy close to DFT calculation with much lower computational cost.
Testing the consistency of propagation between light and heavy cosmic ray nuclei *
Authors: Wang Yu , Wu Juan , Long Wei-Cheng
Published: May 2022

One of the fundamental challenges in cosmic ray physics is to explain the nature of cosmic ray acceleration and propagation mechanisms. Owing to the precise cosmic ray data measured by recent space experiments, we can investigate cosmic ray acceleration and propagation models more comprehensively and reliably. In this paper, we combine the secondary-to-primary ratios and primary spectra measured by PAMELA, AMS02, ACE-CRIS, and Voyager-1 to constrain the cosmic ray source and transport parameters. The study shows that the

data yield a medium-energy diffusion slope

and a high-energy slope

. The

species place a looser constraint on

but a tighter constraint on

. The overlaps imply that heavy and light particles can provide compatible results at medium to high energies. Moreover, both the light and heavy nuclei indicate a consistent diffusion slope variation

at

GV. At low energies, significant disagreements exist between heavy and light elements. The boron-to-carbon ratio requires a much larger diffusion slope shift

at approximately 4 GV or a stronger Alfvén velocity

than the low-mass data. This indicates that the heavy and light particles may suffer different low-energy transport behaviors in the galaxy. However, a better understanding of the consistency/inconsistency between the heavy and light cosmic rays relies on more precise cross-sections, better constraints on correlations in systematic errors of data, a more accurate estimation of the galaxy halo size, and a more robust description of solar modulation during the reversal period of the heliospheric magnetic field.
Diagnostic Functions of Solar Coronal Magnetic Fields from Radio Observations
Authors: Tan Baolin
Published: May 2022

In solar physics, it is a big challenge to measure the magnetic fields directly from observations in the upper solar atmosphere, including the chromosphere and corona. Radio observations are regarded as the most feasible approach to diagnose the magnetic field in solar chromosphere and corona. However, because of the complexity and diversity of the emission mechanisms, the previous studies have only presented the implicit diagnostic functions of the magnetic field for specific mechanism from solar radio observations. This work collected and sorted out all methods for diagnosing coronal magnetic field from solar radio observations, which are expressed as a set of explicit diagnostic functions. In particular, this work supplemented some important diagnostic methods missed in other reviews. This set of diagnostic functions can completely cover all regions of the solar chromosphere and corona, including the quiet region, active region and flaring source regions. At the same time, it also includes incoherent radiation such as bremsstrahlung emission of thermal plasma above the quiet region, cyclotron and gyro-synchrotron emissions of magnetized hot plasma and mildly relativistic nonthermal electrons above the active regions, as well as coherently plasma emission around flaring source regions. Using this set of diagnostic functions and the related broadband spectral solar radio imaging observations, we can derive the magnetic fields of almost all regions in the solar atmosphere, which may help us to make full use of the spectral imaging observations of the new generation solar radio telescopes (such as MUSER, EVOSA and the future FASR, etc.) to study the solar activities, and provide a reliable basis for the prediction of disastrous space weather events.
Two New r-process-enhanced Stars with [Fe/H] > −0.6 dex from the LAMOST-MRS Survey
Authors: Xie Xiao-Jin , Shi Jian-Rong , Chen Tian-Lu , Yan Hong-Liang , Chen Tian-Yi , Pan Kai-Ke , Li Chun-Qian , Liu Shuai , Gao Qi , Yan Tai-Sheng , Ding Ming-Yi
Published: May 2022

We report the discovery of two r-process-enhanced stars with [Fe/H] > −0.6 dex selected from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey. Three candidate stars have been selected from the LAMOST medium-resolution (R ∼ 7500) spectroscopic survey, and the followed-up high signal-to-noise ratio and high-resolution (R ∼ 31,500) spectra are obtained with the ARC Echelle Spectrograph mounted on the 3.5 m telescope at the Apache Point Observatory, which allow us for the determination of stellar atmospheric parameters and abundances of 20 elements. Among these three r-process-enhanced candidate stars, TYC 1710-933-1 and TYC 2858-372-1 have [Eu/Fe] higher than 0.3 dex and [Ba/Eu] lower than 0.0 dex, thus, can be identified as new r-process-enhanced objects. TYC 2858-372-1 shows similar r+s-process pattern to the Sun. TYC 1710-933-1 presents enhancement of the r-process elements of Nd and Eu. Our work indicates that the enrichment mechanisms of the heavy neutron-capture elements are complicated for metal-rich stars.