bluuebunny/crossref_metadata_2025 huggingface dataset:
A coupled electrocatalytic system with reduced energy input for CO2 reduction and biomass valorization
Authors: Liu Shao-Qing , Gao Min-Rui , Wu Shuwen , Feng Renfei , Wang Yicheng , Cui Linfang , Guo Ying , Fu Xian-Zhu , Luo Jing-Li
Published: September 2023

A cathodic electrochemical CO2 reduction to formate coupled anodic 5-hydroxymethylfurfural electrooxidation to 2,5-furandicarboxylic acid pair electrolysis system was developed for CO2 conversion and biomass valorization with low energy consumption.
Systematic safety evaluation of quasi-solid-state lithium batteries: a case study
Authors: Li Wei , Li Hang , Liu Jiaxiang , Lin Shini , Chen Qichen , Ji Weijie , He Zheng , Zhang Peng , Zhao Jinbao
Published: September 2023

In the face of the upcoming application of solid-state batteries, we systematically analyze their thermal runaway path and explain its safety improvement mechanism using a case study.
Rapid and easily identifiable blood typing on microfluidic cotton thread-based analytical devices
Authors: Min Shuqiang , Zhan Tonghuan , Lu Yang , Pan Deng , Chen Xiaoqing , Xu Bing
Published: September 2023

We present a novel swing-elution-based method to achieve rapid, cost-effective, and easily identifiable blood typing assays.
Recent advances in targeted nanoparticle drug delivery systems for ischaemic stroke
Authors: Li Xiaojun , Wang Qi , Fang Qi , Xu Jianling , Han Baosong , Chen Yongquan , Yao Weidong , Ye Sheng , Wang Bin
Published: September 2023

Targeted nanoparticles can be used to treat ischemic stroke by targeting the complex pathological mechanism of ischemic stroke and the blood–brain barrier that is difficult to penetrate by most traditional drugs.
Nonlinear impedance matching control for a submerged wave energy converter
Authors: Gonzalez‐Esculpi Alejandro , Verde Cristina , Maya‐Ortiz Paul
Published: September 2023

The impedance matching control, also known as approximate complex conjugate control (ACC), is one of the main strategies for improving the capture of energy by point absorber wave energy converters. Such a strategy shapes the mechanical impedance related to the floater dynamics via the control law. Since the traditional ACC is given by a linear control law, this work proposes a generalization denoted as nonlinear complex conjugate control (NCC) that considers the presence of nonlinear viscous damping in addition to the usual linear damping and stiffness. The energy maximization conditions for the proposed NCC are derived in the frequency domain through the describing function method. These conditions show that the ACC is a special case of the NCC when the total damping on the floater is approximated as a linear function of its velocity. From numerical simulations of a point absorber wave energy converters with nonlinear damping, which is based on the Archimedes wave swing prototype, it is shown that the NCC provides greater energy conversion than the ACC, as well as a robust performance in the presence of variations of the damping coefficient and the excitation force peak frequency.
Frequency‐trajectory‐oriented control strategy for primary frequency regulation of wind farms
Authors: Yang Xusong , Liu Lei , Gu Xinyu , Luo Xianjue
Published: October 2023

With the rapid increase of wind power penetration, the frequency indicators of power system, encompassing frequency deviation and rate of change of frequency (RoCoF), are prone to exceed the pertinent relay thresholds, thus leading to serious power outages. Wind farms can participate in primary frequency regulation (PFR) to alleviate the above problem. However, wind farms reserve capacity (WFRC) presented by overspeed control and pitch angle control is the important factor for frequency safety especially when large disturbance occurs, and it varies obviously in different conditions. Thus, WFRC should be utilized optimally to avoid insufficient or excessive response of wind farms in PFR. To overcome the challenge, this paper proposes frequency‐trajectory‐oriented control (FTOC) for wind farms based on a two‐fold optimization framework, seeking to obtain the best frequency control performances in PFR through realizing the optimal compromise between frequency results and the consumption of WFRC. First, when the frequency indicators deviate significantly from the normal values, the optimal frequency trajectory is planned periodically according to the local standards and operation conditions, thereby minimizing the total consumption of WFRC on the premise of frequency safety. Second, based on model predictive control and a real‐time power system parameters estimator, the total reference power of wind farms, which helps the frequency track the latest planned trajectory, is optimally distributed among wind generators according to their reserve capacity. In this case, through the optimal frequency trajectory planning and tracking, the new method in this paper not only effectively prevents the frequency results from exceeding the local standards under diverse conditions, but also finds the optimal balance among frequency indicators safety, frequency trajectory smoothness, and the reserve capacity consumption of wind power generators. Finally, the simulation results prove the effectiveness and advancement of FTOC.
Behaviour analysis of H‐bridge high‐voltage capacitor banks fault on 230‐kV substation using discrete wavelet transform
Authors: Chiradeja Pathomthat , Lertwanitrot Praikanok , Ngaopitakkul Atthapol , Pothisarn Chaichan
Published: October 2023

The protection of traditional high‐voltage capacitor banks relies on an unbalance relay which operates when an internal fuse is blown. However, the unbalance relay cannot indicate the cause of the fault. Thus, an operator wastes time and human resources investigating the fault issues. In this paper, a fault which occurred in a 230‐kV power system of Electricity Generating Authority of Thailand was observed by performing simulations using the Power Systems Computer Aided Design (PSCAD) program. The study system based on the double bus station and 72 MVAR capacitor banks was installed in the form of a back‐to‐back topology. Three scenarios were considered: normal condition, fault occurrence in one capacitor bank and fault occurrence in both capacitor banks. Current characteristics such as the current phase and difference in unbalance current were considered. In addition, discrete wavelet transform was applied to solve the ambiguity of current generated from the PSCAD. The authors’ results suggest that identifying fault events using a coefficient of wavelet is more efficient than relying on the current amplitude. The findings mentioned in this paper can be applied in a traditional power system protection scheme to enhance a system's reliability.
Resilience of modern power distribution networks with active coordination of EVs and smart restoration
Authors: Alghamdi Abdullah Ali M. , Jayaweera Dilan
Published: October 2023

In this modern era of cyber–physical–social systems, there is a need of dynamic coordination strategies for electric vehicles (EVs) to enhance the resilience of modern power distribution networks (MPDNs). This paper proposes a two‐stage EV coordination framework for MPDN smart restoration. The first stage is to introduce a novel proactive EV prepositioning model to optimize planning prior to a rare event, and thereby enhance the MPDN survivability in its immediate aftermath. The second stage involves creating an advanced spatial–temporal EV dispatch model to maximize the number of available EVs for discharging, thereby improving the MPDN recovery after a rare event. The proposed framework also includes an information system to further enhance MPDN resilience by effectively organizing data exchange among intelligent transportation system and smart charging system, and EV users. In addition, a novel bidirectional geographic graph is proposed to optimize travel plans, covering a large penetration of EVs and considering variations in traffic conditions. The effectiveness is assessed on a modified IEEE 123‐node test feeder with real‐world transportation and charging infrastructure. The results demonstrate a significant improvement in MPDN resilience with smart restoration strategies. The validation and sensitivity analyses evidence a significant superiority of the proposed framework.
An adaptive distance protection back‐up scheme for transmission lines connected to doubly fed induction generator wind farms based on setting groups procedure
Authors: Fattahyan Yousef , Ramezani Nabiollah , Ahmadi Iraj
Published: October 2023

Generally, wind speed alters continuously during a day and leads to fluctuating output power of a wind farm (WF). Connecting such a WF to the transmission line of grid causes a malfunction in the performance of the backup zone of the distance relays due to the random nature of generation and the number of connected wind turbines (WF penetration). In this study, a new adaptive setting groups‐based method has been proposed to set the second zone of the distance relay in the grid with a WF equipped with a doubly fed induction generator. In this method, the authors have also taken into account the uncertainty of wind fluctuations and the availability of WT. A Markov model is developed to implement these features. To determine the impedance setting of each of the set groups of the second zone in the distance relays of the remote bus, the obtained impedances are clustered in four clusters by using the combination of K‐means and particle swarm optimization algorithms. Finally, the details of the analysis results of this issue have been compared with other methods available in the literature. The validity and accuracy of the proposed approach also have been assayed and confirmed.
A review of electric vehicle hosting capacity quantification and improvement techniques for distribution networks
Authors: Fatima Samar , Püvi Verner , Lehtonen Matti , Pourakbari‐Kasmaei Mahdi
Published: October 2023

The electrification of the transport sector to control the carbon footprint has been gaining momentum over the last decade with electric vehicles (EVs) seen as the replacement for conventional internal combustion engines. Economic incentives, subsidies, and tax exemptions are also paving the way for rising EV penetration in the power distribution networks. However, the exponential EV adoption requires careful technical and regulatory analysis of traditional networks to satisfy the network reliability constraints. Therefore, it would be vital to find EV hosting capacity (HC) limits of networks from a multifaceted approach involving various market players, mainly distribution system operators and EV owners. This review provides a systematic categorization of EV hosting capacity evaluation and improvement methods, thus enabling researchers and industry personnel to navigate the advancing landscape of EVs. This novel framework extends beyond the theoretical implication of diverse objective functions and HC improvement methods to the actual numerical values of EV HC across varying geographical settings. Therefore, this unique synthesis of varying aspects of EV HC facilitates the in‐depth understanding of the integration of sustainable energy and transport sector.
A two‐stage iterative method for short‐wave source localisation
Authors: Jiang Linqiang , Tang Tao , Wu Zhidong , Zhao Paihang , Zhang Ziqiang
Published: October 2023

Short‐wave source localisation has an important role in many fields. A two‐stage iterative algorithm is proposed based on the ionospheric virtual height (IVH) model using the direction of arrival (DOA) and time difference of arrival (TDOA) measurements, which is divided into DOA stage and TDOA stage. The optimisation problem of the TDOA stage can be obtained by using the result of DOA stage and TDOA measurements. During the solution process, the non‐convex quadratic equation constraints are converted to linear constraints, which can lead to the algorithm converges to the global optimal solution and the optimal solution can be analytically solved. The theoretical analysis demonstrates that the localisation accuracy of both stages can reach the corresponding constrained Cramér‐Rao lower bound (CCRLB). And the accuracy of TDOA stage achieves the CCRLB of hybrid localisation. Finally, the performance of the proposed method is demonstrated by simulations.
Identification of basement membrane markers in diabetic kidney disease and immune infiltration by using bioinformatics analysis and experimental verification
Authors: Shi Rui , Zhao Wen‐Man , Zhu Li , Wang Rui‐Feng , Wang De‐Guang
Published: September 2023

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease worldwide. Basement membranes (BMs) are ubiquitous extracellular matrices which are affected in many diseases including DKD. Here, the authors aimed to identify BM‐related markers in DKD and explored the immune cell infiltration in this process. The expression profiles of three datasets were downloaded from the Gene Expression Omnibus database. BM‐related differentially expression genes (DEGs) were identified and Kyoto encyclopaedia of genes and genomes pathway enrichment analysis were applied to biological functions. Immune cell infiltration and immune function in the kidneys of patients with DKD and healthy controls were evaluated and compared using the ssGSEA algorithm. The association of hub genes and immune cells and immune function were explored. A total of 30 BM‐related DEGs were identified. The functional analysis showed that BM‐related DEGs were notably associated with basement membrane alterations. Crucially, BM‐related hub genes in DKD were finally identified, which were able to distinguish patients with DKD from controls. Moreover, the authors observed that laminin subunit gamma 1(LAMC1) expression was significantly high in HK2 cells treated with high glucose. Immunohistochemistry results showed that, compared with those in db/m mouse kidneys, the levels of LAMC1 in db/db mouse kidneys were significantly increased. The biomarkers genes may prove crucial for DKD treatment as they could be targeted in future DKD treatment protocols.
Neuroprognostication: Guillain–Barré Syndrome
Authors: Traub Rebecca , Chaudhry Vinay
Published: October 2023

Guillain–Barré syndrome is an immune-mediated disease of the peripheral nerves characterized by rapidly progressing symmetric weakness, areflexia, and albuminocytological dissociation. Most patients reach their nadir within 2 weeks. Disease severity can be mild to severe, with 20% of patients requiring mechanical ventilation. Intravenous immunoglobulin and plasma exchange are equally effective treatments. Monitoring strength, respiratory function, blood pressure, and heart rate, as well as pain management and rehabilitative therapy are important aspects of management. About 20% of patients require assistance to walk at 6 months. Older age, preceding diarrhea, and lower Medical Research Council (MRC) sum scores predict poor outcome. Death from cardiovascular and respiratory complications can occur in the acute or recovery phases of the illness in 3 to 7% of the patients. Risk factors for mortality include advanced age and disease severity at onset. Neuropathic pain, weakness, and fatigue can be residual symptoms; risk factors for these include axonal loss, sensory involvement, and severity of illness.
Responsiveness of the Immune System to Nanomedicine during Coronavirus Infections: Literature Review and Bibliometric Analysis
Authors: Ur Rehman Tanzeel , Woodman Alexander , Rasheed Mohammad , Zahid Misbah
Published: October 2023

Objective Nanomedicine can play an important role in the various stages of prevention, diagnosis, treatment, vaccination, and research related to coronavirus disease 2019 (COVID-19). While nanomedicine is a powerful interdisciplinary means that offers various approaches in patient treatment, a number of factors should be critically studied to find approaches and mechanisms in the prevention, diagnosis, and treatment of this disease. This bibliometric analysis was designed to explore studies on the current knowledge of the structure, its mechanism of cell binding, and the therapeutic effect of nanomedicine on COVID-19.

Materials and Methods The study data was searched from Web of Science Core Collection(WoSCC) between 2017 and 2021. Biblioshiny and VOSviewer were used to analyze and visualize patterns in scientific literature derived from WoS.

Results The three clusters of keywords resulted relating to aim. Cluster 1 looking into epidemiological and public health studies on COVID-19. Cluster 2 included terms associated with virus transition, such as receptor binding, membrane glycoprotein, membrane fusion, and viral envelope proteins. Cluster 3 involved high-frequency keywords associated with nanomedicine, such as metal nanoparticles, drug delivery system doxorubicin, immunology, immune response, inflammation, and unclassified drug. Keywords such as “nanotechnology” and “gold nanoparticles” were at the center of COVID-19 related clusters, indicating the importance of these areas during the outbreak.

Conclusions Understanding the advanced virology of coronaviruses and interfering with their spread through nanomedicine could significantly impact global health and economic stability. Continuous research is needed to accelerate the transfer of nanomedicine results into practice of treatment without risk of side effects.
Monetary policy models: lessons from the Eurozone crisis
Authors: Gutiérrez-Diez Pedro J. , Pál Tibor
Published: October 2023

This paper theoretically and empirically investigates the puzzling decade-long concurrence of expansionary monetary and fiscal policies, decreasing credit flows, fall in price levels, and sluggish real activity observed in the Euro area from the outset of the 2007–2008 financial crisis. To this end, we propose a monetary general equilibrium model that clarifies the transmission mechanisms, debt–deflation channels, and the paramount role of financial leverage decisions underlying these peculiarities. On this basis, a vector error correction model is specified which confirms the theoretical predictions and provides insights into the elements specific to the long-term relations. In addition, the estimated impulse response functions document the associated short-term dynamics outlining the debt–deflation mechanism.
Knowledge-based HRM and business process innovation in the hospitality industry
Authors: Sarfraz Muddassar , Khawaja Kausar Fiaz , Khalil Mahmoona , Han Heesup
Published: September 2023

This study examines the impact of knowledge-based HR practices on business process innovation under the moderating role of Knowledge-Centered Organizational Culture (KCOC) and the mediating role of Absorptive Capacity (AC). Data was collected from the managers of hospitality firms via questionnaires from May to September 2022, using a quantitative data analytic process. The results demonstrate that formal and informal knowledge-based HR practices are vital to achieving business innovation performance with interpersonal AC mediating and KCOC moderating. The findings of our study provide research-based practical implications for various stakeholders and a significant theoretical contribution to fill the research gap in the literature. This research presents empirical insights that are applicable to the management of the hotel industry.
Construction of symmetric paired choice experiments: minimising runs and maximising efficiency
Authors: Alamri Abdulrahman S. , Georgiou Stelios D. , Stylianou Stella
Published: October 2023

Discrete choice experiments (DCEs) are popular in various fields such as health resources, marketing, transport, economics, and many others for identifying the factors that influence an individual’s choice behaviour. Selecting the DCE design is crucial in determining the observable effects. In this paper, the optimal form of the information matrix is introduced for attributes at two levels, main effect models, and equal choice probabilities for paired choice experiments. Additionally, the construction of D-optimal designs is modified to obtain DCEs when the number of attributes equals the number of runs, including designs with choice sets of sizes that are not necessarily multiples of 4, i.e. N ≢ 0mod4. The designs suggested in this paper have the same or higher D-efficiencies than existing efficient designs for the same number of choice sets. Moreover, the proposed design techniques can be extended to be applied to situations where the attributes of DCEs have a higher number of levels (ℓ > 2), resulting in designs with the same improved D-efficiencies and sufficiently small sample sizes. The designs proposed in this paper offer a notable advantage by allowing a reduction of 33% in the number of choice pairs with only a marginal loss of 11% in D-efficiency when compared to an optimal design. In comparison, the design suggested by other researchers incurs a higher loss in D-efficiency.
On asymptotic stability of solitons for 2D Maxwell–Lorentz equations
Authors: Kopylova E. A. , Komech A. I.
Published: October 2023

We prove asymptotic stability of solitons for the 2D Maxwell–Lorentz equations with an extended charged particle. Soliton solutions correspond to the uniform motion of a particle. Our main result is as follows: the particle for large times moves asymptotically uniformly, and the Maxwell field asymptotically is the sum of the comoving field and the dispersive wave. The remainder converges to zero in the global energy norm.
Design, calibration, and performance of a uniaxial pressure cell for neutron scattering studies of quantum magnetism
Authors: Sandberg L. Ø. , Haubro M. L. , Krighaar K. M. L. , Edberg R. , Fjellvåg I. M. B. , Guthrie M. , Holmes A. T. , Mangin-Thro L. , Wildes A. , Henelius P. , Lefmann K. , Deen P. P.
Published: October 2023

We provide an overview of a pressure cell designed to apply uniaxial pressure to single crystals for the study, by neutron scattering techniques, of strongly correlated magnetic systems and, in particular, quantum magnets. A detailed overview of the pressure cell components, their requirements, and links to the scientific and technical specifications are presented. The pressure cell is able to accommodate a 200 mm3 single crystal that can be pressurized up to 2 GPa at cryogenic temperatures. The pressure cell is consistent with the requirements of inelastic neutron scattering and, importantly, neutron polarization analysis. A particular strength of the uniaxial pressure cell is the highly uniform and low background for a wide scattering angle of 360° horizontally and ±20° vertically. We show the performance of the uniaxial pressure cell using a relevant neutron scattering instrument, the polarized diffuse scattering instrument, D7. The experiments confirm that the cell complies with the scientific and technical requirements. This uniaxial pressure cell will provide a useful additional tool in the sample environment suite available for the study of quantum magnetism.
Spin-polarized electron beam generation in the colliding-pulse injection scheme
Authors: Gong Zheng , Quin Michael J. , Bohlen Simon , Keitel Christoph H. , Põder Kristjan , Tamburini Matteo
Published: October 2023

Employing colliding-pulse injection has been shown to enable the generation of high-quality electron beams from laser–plasma accelerators. Here, by using test particle simulations, Hamiltonian analysis, and multidimensional particle-in-cell simulations, we lay the theoretical framework for spin-polarized electron beam generation in the colliding-pulse injection scheme. Furthermore, we show that this scheme enables the production of quasi-monoenergetic electron beams in excess of 80% polarization and tens of pC charge with commercial 10-TW-class laser systems.
Azimuthal and axial dispersion relations of low-frequency oscillations in partially magnetized plasma with crossed electric and magnetic fields
Authors: Lee Minkeun , Cheon Cheongbin , Choi Jinyoung , Lee Hae June , Hwang Y. S. , Chung Kyoung-Jae , Kim June Young
Published: October 2023

This paper presents the results of the azimuthal and axial wave diagnostics of a partially magnetized E × B Penning source. Various probes were employed, namely, a two-tip probe for azimuthal waves and two- and four-probe arrays for axial waves, to investigate the spatial characteristics of the instability using a two-point probe technique. The azimuthally aligned tips of the two-tip probe facilitated the investigation of the evolution of the azimuthal dispersion relation, which exhibited a well-known azimuthally propagative spoke at low discharge voltages. By utilizing axially aligned four-probe arrays with a probe distance of 3 mm and two-probe arrays with a relatively long probe distance of 20 mm, we sought to determine whether the rotating spoke propagated in the axial direction in the cylindrical E × B source. Our findings suggest that the rotating spoke originated near the axial center and propagated toward each cathode, rotating in a direction tilted from the azimuthal direction.
Liouville-type results for time-dependent stratified water flows over variable bottom in the β-plane approximation
Authors: Martin Calin Iulian
Published: October 2023

We consider here time-dependent three-dimensional stratified geophysical water flows of finite depth over a variable bottom with a free surface and an interface (separating two layers of constant and different densities). Under the assumption that the vorticity vectors in the two layers are constant, we prove that bounded solutions to the three-dimensional water waves equations in the β-plane approximation exist if and only if one of the horizontal components of the velocity, as well as its vertical component, are zero; the other horizontal component being constant. Moreover, the interface is flat, the free surface has a traveling character in the horizontal direction of the nonvanishing velocity component, being of general type in the other horizontal direction, and the pressure is hydrostatic in both layers. Unlike previous studies of three-dimensional flows with constant vorticity in each layer, we consider a non-flat bottom boundary and different constant vorticity vectors for the upper and lower layer.
Constraining chaos: Enforcing dynamical invariants in the training of reservoir computers
Authors: Platt Jason A. , Penny Stephen G. , Smith Timothy A. , Chen Tse-Chun , Abarbanel Henry D. I.
Published: October 2023

Drawing on ergodic theory, we introduce a novel training method for machine learning based forecasting methods for chaotic dynamical systems. The training enforces dynamical invariants—such as the Lyapunov exponent spectrum and the fractal dimension—in the systems of interest, enabling longer and more stable forecasts when operating with limited data. The technique is demonstrated in detail using reservoir computing, a specific kind of recurrent neural network. Results are given for the Lorenz 1996 chaotic dynamical system and a spectral quasi-geostrophic model of the atmosphere, both typical test cases for numerical weather prediction.
Dynamics of dielectric micropore discharge in atmospheric pulsed dielectric barrier discharge
Authors: Gu Lili , Zhang Yarong , Fang Junlin , Xu Shaofeng , Guo Ying , Shi Jianjun
Published: October 2023

In this paper, a two-dimensional self-consistent fluid model was developed in atmospheric helium for dielectric barrier discharge excited by microsecond voltage pulses, in which a dielectric sheet with micropore is inserted in the interelectrode gap. It demonstrates that the discharge generated in dielectric micropore is in the form of propagating ionization wave, which reaches the plasma density of 1.32 × 1020 m−3 and the mean electron energy of 17.70 eV. The transverse electric field perpendicular to the applied longitudinal electric field in dielectric micropore is found to play an important role on the electron acceleration and generation, which is induced by the space charges in the micropore. The migration fluxes of electron and ions driven by electric field and diffusion explains the formation of transverse electric field and sheath regions above the dielectric surfaces.
Flow regime identification and flow instability analysis of oscillatory flows over twin circular cylinders
Authors: Lu Lin , Zhou Zhongbing , Zhang Cheng
Published: October 2023

Oscillatory flows past two identical circular cylinders are investigated by two-dimensional direct numerical simulations in the parameter space of gap ratio (0.5 ≤ G ≤ 4.0), angle of flow incidence (0° ≤ α ≤ 90°) and Keulegan–Carpenter number (4 ≤ KC ≤ 12) with a constant Reynolds number Re = 150, where G = L/D, KC = UmT/D and Re = UmD/υ with D being the dimeter of the identical cylinders, L the shortest surface-to-surface distance between the two cylinders, Um and T being the velocity amplitude and period of the sinusoidal oscillatory flow, respectively, and α is defined as the angle between the flow direction to the line connecting the centers of the two cylinders. Comparing with the tandem or side-by-side arrangements of twin circular cylinders in oscillatory flows, the staggered twin cylinders (0° < α < 90°) involve more diverse flow regimes, including the periodic, quasi-periodic and chaotic flow states, due to the inherent asymmetric flow interference around the cylinder pair. In addition to introducing four flow regimes for the tandem and side-by-side arrangements, this study newly identifies 11 flow regimes for the staggered twin cylinders. The newly reported flow regimes in this work are collaboratively identified through the flow visualizations, steady streaming, frequency spectra of fluid forces and Lissajous phase diagrams, as well as the temporal-spatial symmetry features of the wake flows. Connecting with the previous work by Zhao and Cheng [“Two-dimensional numerical study of vortex shedding regimes of oscillatory flow past two circular cylinders in side-by-side and tandem arrangements at low Reynolds numbers,” J. Fluid Mech. 751, 1–37 (2014)], this study presents overall regime maps in the KC-α plane for varied gap ratios. It is found that the flow regimes previously and presently identified for the tandem and side-by-side arrangements may also appear for the staggered twin cylinders. The present numerical results suggest the sensitive dependence of the flow regimes on the parameters of KC, α, and G. It is also found that a specific flow regime with narrow parameter bands may appear within another flow regime, forming the abnormal regime hole in the regime map. To understand the profound influence of the control parameters on the flow regime transition, and the relevant temporal-spatial symmetry breaking, the linear Floquet stability analysis is conducted in this work. It was confirmed that the variation of the KC number may result in the Ky symmetry breaking over several periodic flow regimes, while the change of the angle of flow incidence may account for the H2 symmetry covering various periodic and quasi-periodic flow regimes. The stability analysis also explains the temporal flow transition and the abnormal occurrence of the regime holes within either quasi-periodic or chaotic flow regimes.
Passivation of CdTe/MgCdTe double heterostructure by dielectric thin films deposited using atomic layer deposition
Authors: Abbasi Haris Naeem , Qi Xin , Gong Jiarui , Ju Zheng , Min Seunghwan , Zhang Yong-Hang , Ma Zhenqiang
Published: October 2023

This work reports a study of the passivation effects of different dielectric thin films deposited on monocrystalline CdTe/MgCdTe double heterostructures (DHs) using atomic layer deposition (ALD). Enhanced photoluminescence intensity was observed in all DHs with surface passivation, and increased photogenerated carrier lifetime was observed in DHs with HfO2, TiO2, Al2O3, and TiN passivated CdTe/MgCdTe DHs. These results have demonstrated effective suppression of the undesired surface recombination of CdTe/MgCdTe DHs by dielectric thin films deposited via ALD.
Phase-sensitive analysis of a two-color infrared photodetector using photoreflectance spectroscopy
Authors: Zeinalvand Farzin Behnam , Lee DongKun , Kang Tae In , Kim Jong Su , Kim Geun Hyeong , Lee Sang Jun , Kim Yeongho
Published: October 2023

The phase diagrams of photoreflectance spectra were investigated for an InGaAs two-color infrared photodetector. The diagrams for a high excitation intensity revealed that the spectrum is multi-component. The origin of these components was investigated, and the photoreflectance spectra and phase diagrams were also measured for an angle-polished version at different depths. With the help of the polished sample, the variation of the phase delay angles and the trapping time constants was tracked for different depths. Additionally, the polished version enables us to find a confirmation for the origins of the multi-component nature of the whole phase diagram. It can be concluded that when the phase delays or time constants of various components are very close, more attention should be paid to interfering with the phase-sensitive investigations of layered materials. As a main result, the consistency of the phase delay with interface trap densities was confirmed qualitatively. Using a reciprocal space map of the sample, this result can be a piece of experimental evidence for a correlation between the photoreflectance time constant and trap densities in the junctions. This non-contact method enables the characterization of layered devices, offering a valuable tool for achieving high-performance devices.
Mechanism of silicon-nanowire-diode orientation in DC electric fields
Authors: Hoang Minh-Thang , Deshmukh Nishant , Mohabir Amar T. , Feldman Leonard C. , Filler Michael A. , Shan Jerry W.
Published: October 2023

Doped semiconductor nanowires are emerging as next-generation electronic colloidal materials, and the efficient manipulation of such nanostructures is crucial for technological applications. In fluid suspension, pn nanowires (pn NWs), unlike homogeneous nanowires, have a permanent dipole, and thus, experience a torque under an external DC field that orients the nanowire with its n-type end in the direction of the field. Here, we quantitatively measure the permanent dipoles of various Si nanowire pn diodes and investigate their origin. By comparing the dipoles of pn NWs of different lengths and radii, we show that the permanent dipole originates from non-uniform surface-charge distributions, rather than the internal charges at the p–n junction as was previously proposed. This understanding of the mechanism for pn NWs orientation has relevance to the manipulation, assembly, characterization, and separation of nanowire electronics by electric fields.
Detectivity enhancement by double radiation pass in interband cascade infrared photodetectors
Authors: Bader A. , Rothmayr F. , Khan N. , Koeth J. , Hartmann F. , Höfling S.
Published: October 2023

The detectivity enhancement in a double-pass architecture in an interband cascade infrared photodetector (ICIP) is investigated. The ICIP consists of twelve identically thick absorbers composed of an InAs/GaSb type-II superlattice. To achieve a double-pass of radiation, a multilayer backside mirror was sputter-deposited after thinning the undoped GaSb substrate. At room temperature, a differential resistance area product of R0A= 1.37 Ω cm2 was achieved and the ICIP has a cutoff wavelength of 6.5 μm. By adding a backside mirror to the device, the responsivity was increased by 47% caused by the double radiation pass through the absorber. This resulted in a room temperature zero-bias detectivity of 8.3 × 108 Jones at a wavelength of 5.27 μm. Furthermore, oscillations are observed in the detectivity due to light interference from the reflected beam at the semiconductor/metal interface, which manifests the reflected double-pass device functionality unequivocally in the device characteristics.
Control of a circular cylinder flow using attached solid/perforated splitter plates at deflection angles
Authors: Wang Chenghui , Li Yong
Published: October 2023

Control of a circular cylinder flow by rear-attached solid/perforated splitters has been experimentally investigated using Particle Image Velocimetry (PIV) and far-field microphones, respectively. The Reynolds number is Re = 2.7 × 104–6.8 × 104 based on the cylinder diameter D, and the effects of splitter length L (L/D = 0–4.0), porosity σ (0%–22%), and deflection angle α (0°–30°) on noise and flow characteristics are reported. The literature seriously lacks the combination effects of these parameters on bluff-body wakes, especially the flow mechanism on noise variations. Acoustic results show that for a solid splitter, the optimal noise reduction of 18 dB is achieved when L/D = 1.0–1.5, whereas when 2.0 ≤ L/D ≤ 4.0, the noise increases rather than decreases, consistent with the literature. At L/D = 1.0, deflecting and/or perforating the splitter would not further reduce the noise and, on the contrary, weaken the noise control efficiency. However, at L/D = 2.0, a rear-half perforation with σ ≥ 18.2% or a deflection angle of α ≥ 30° individually reduces noise by more than 10 dB compared to the bare cylinder. Combining both methods at L/D = 2.0 eliminates vortex-shedding noise when σ ≥ 11.6% and α ≥ 20°. PIV measurements reveal that noise reduction at L/D = 1.0 results from reduced vortex strength in the flow, while noise increase at L/D = 2.0 is attributed to vortex-splitter trailing edge interaction, which is mitigated by the perforation and/or the deflection of the splitter. The study suggests that, in general, appropriately perforating and deflecting longer splitter plates (L/D ≥ 2.0) effectively reduce bluff-body noise, while solid, shorter splitter plates (0.5 ≤ L/D ≤ 1.5) positioned streamwise achieve significant noise reduction. These insights offer valuable noise control strategies for various engineering applications.
Optical measurement of the work function and the field reduction factor of metallic needle tips
Authors: Meier Stefan , Heimerl Jonas , Dienstbier Philip , Hommelhoff Peter
Published: October 2023

Quintessential parameters for needle tip-based electron sources are the work function, the tip apex radius, and the field reduction factor. They determine the static emission properties and strongly influence laser-triggered photoemission experiments at these needle tips. We present a simple method based on photoemission with two different commonly available continuous-wave laser diodes to determine both parameters in situ. We demonstrate our technique at tungsten needle tips. In a first application, use the method to in situ monitor changes of the emitter caused by illumination with strong femtosecond laser pulses. After illumination, we observe an increase in the work function caused by laser-induced changes to the apex of the tip. These changes are reversible upon field evaporation and are accompanied by a change in the spatial electron emission distribution. We believe that this simple in situ work function determination technique is applicable to any metal and in many experimental settings.
Linear and symmetric synaptic weight update characteristics in van der Waals heterostructure transistors based on 2D In4/3P2Se6 barrier layer
Authors: Luo Gaoli , Wang Zhiyi , Wang Mengna , Zhao Jiarong , Cao Dingwen , Li Shasha , Yan Yong
Published: October 2023

Two-dimensional van der Waals heterostructures with fast-switching speed and ultra-low power consumption are promising building blocks for artificial synaptic devices (ASD) that aim to solve problems faced by traditional computing. However, the nonlinearity and asymmetry of synaptic weight updates in artificial synapses have hindered the achievement of high image classification accuracy in most reported neuromorphic networks. Here, we develop a nonvolatile MoS2/In4/3P2Se6/graphene ASD with excellent performance. Due to the intrinsic low conduction band offset (0.86 eV) of MoS2/In4/3P2Se6, the vdW heterostructure device exhibits an ultra-large storage window of 71.2 V at ±40 V back-gate sweep, a low nonlinear factor of 0.014/0.042, and a low asymmetry factor at 0.028. Additionally, the device exhibits synaptic behaviors including excitatory postsynaptic current, pair-pulse facilitation, and important “learning-experience” synaptic function under electrical and optical stimulation. This work indicates that In4/3P2Se6 provides remarkable opportunities for band alignment-related applications and can facilitate ongoing research of neuromorphic functional electronics.
Out-of-contact peeling caused by elastohydrodynamic deformation during viscous adhesion
Authors: Shao Xingchen , Wang Yumo , Frechette Joelle
Published: October 2023

We report on viscous adhesion measurements conducted in sphere-plane geometry between a rigid sphere and soft surfaces submerged in silicone oils. Increasing the surface compliance leads to a decrease in the adhesive strength due to elastohydrodynamic deformation of the soft surface during debonding. The force-displacement and fluid film thickness-time data are compared to an elastohydrodynamic model that incorporates the force measuring spring and finds good agreement between the model and data. We calculate the pressure distribution in the fluid and find that, in contrast to debonding from rigid surfaces, the pressure drop is non-monotonic and includes the presence of stagnation points within the fluid film when a soft surface is present. In addition, viscous adhesion in the presence of a soft surface leads to a debonding process that occurs via a peeling front (located at a stagnation point), even in the absence of solid–solid contact. As a result of mass conservation, the elastohydrodynamic deformation of the soft surface during detachment leads to surfaces that come closer as the surfaces are separated. During detachment, there is a region with fluid drainage between the centerpoint and the stagnation point, while there is fluid infusion further out. Understanding and harnessing the coupling between lubrication pressure, elasticity, and surface interactions provides material design strategies for applications such as adhesives, coatings, microsensors, and biomaterials.
Application of the visual boundary recurrence plots to magnetohydrodynamic turbulence channel flow
Authors: Fragkou Athanasios D. , Karakasidis Theodoros E. , Sarris Ioannis E. , Andreadis Ioannis
Published: October 2023

The visual boundary recurrence plot (VBRP) method is used in this analysis to study time series of fluctuating velocities in turbulent magnetohydrodynamic channel flow that were studied in our previous study using the theory of the recurrence plots. The VBRP is a new graphical tool, which visualizes each point of the recurrence plot with colors depending on whether the neighboring points are recurrent or not and enhances, thus, the study of the stability of the textures of the recurrence plots, viewing them as geometrical shapes. We calculate the VBRPs of the turbulent velocity time series of a simulated channel flow monitored at constant streamwise and spanwise positions and at a number of positions along the wall-normal direction. We further estimate the visual boundary recurrence plot rates to indicate the change of the dynamics of the flow. The results highlight the flow dynamics under the influence of the magnetic field and identify additional correlations/similarities between the flow point positions within the channel. In this study, we show that these areas correspond to perturbations due to strikes that are created close to the boundary and move toward the centerline. It also seems that we have more often creation of streaks in the case of absence of magnetic field.
An innovative experimental apparatus for the analysis of natural gas hydrate cavitation erosion process using laser-induced cavitation
Authors: Huang Haochen , Zhang Yiqun , Jiang Yiquan , Tan Yawen , Wu Xiaoya , Li Gensheng
Published: October 2023

Natural gas hydrates (NGHs) are an emerging source of clean energy distributed in the pores of soil sediments in deep seabed and permafrost zones with abundant reserves. Cavitation contains enormous energy, thus allowing radial cavitation jets to improve drilling and production rates of NGHs. This paper presents an experimental apparatus that was developed to synthesize NGHs and generate cavitation bubbles by laser for the analysis of the erosion rules of NGHs by cavitation in a reservoir environment. The apparatus consists of a working fluid injection and pressure control system, a temperature control and circulation system, a laser-induced cavitation system, a visual reaction vessel, and a data acquisition and measurement system. The laser-induced cavitation erosion on NGHs and multi-bubble interaction experiments can be conducted over temperatures and pressures in the range of 0–20 °C and 0–12 MPa, respectively, in a visualized reaction vessel. Hydrophones and high-speed photography were utilized for monitoring and analyzing the erosion process within the visualized reaction vessel. In addition, bubble groups of different components in various environments can also be tested in this apparatus to obtain the interaction characteristics under different conditions. This paper discusses the basic structure and principle of the apparatus and conducts a series of experiments to verify the effect of cavitation erosion on hydrate and the feasibility of using cavitation to increase production in hydrate exploitation.
The NIST silicon lattice comparator upgrade
Authors: Mendenhall Marcus H. , Cline James P. , Szabo Csilla I. , Henins Albert
Published: October 2023

The NIST silicon lattice comparator has been in service, in various forms, since the 1970s. It is capable of measuring the difference in lattice spacing between specimens of high-quality float-zone silicon to Δd/d ≈ 6 × 10−9. It has recently undergone a thorough update of its control systems and mechanics. These upgrades result in the ability to collect data with improved stability, less settling time of the instrument, and less operator intervention.
Distant RF field sensing with a passive Rydberg-atomic transducer
Authors: Otto J. Susanne , Chilcott Matthew , Deb Amita B. , Kjærgaard Niels
Published: October 2023

We combine a rubidium vapor cell with a corner-cube prism reflector to form a passive RF transducer, allowing the detection of microwave signals at a location distant from the active components required for atomic sensing. This compact transducer has no electrical components and is optically linked to an active base station by a pair of free-space laser beams that establish an electromagnetically induced transparency scenario. Microwave signals at the transducer location are imprinted onto an optical signal which is detected at the base station. Our sensing architecture with a remote standalone transducer unit adds important flexibility to Rydberg-atom based sensing technologies, which are currently subject to significant attention. We demonstrate a ∼30 m link with no particular effort and foresee significant future prospects of achieving a much larger separation between the transducer and the base station.