bluuebunny/crossref_metadata_2025 huggingface dataset:
Combinatorial logic devices based on a multi-path active ring circuit
Authors: Khitun Alexander , Balinskiy Michael
Published: June 2022

In this work, we describe a logic device in which an act of computation is associated with finding a path connecting input and output ports. The device is based on an active ring circuit comprising electric and magnetic parts. The electric part includes an amplifier, a phase shifter, and an attenuator. The magnetic part is a multi-port magnetic matrix comprising delay lines and frequency filters. Signals propagating on different paths may accumulate different phase shifts. Auto-oscillations occur in the circuit when the magnetic and electric parts match each other to meet the resonance amplitude and phase conditions. The system naturally searches for a resonance path that depends on the position of the electric phase shifter and amplification level. The path is detected by the set of power sensors. The proposed logic device can be used for solving a variety of computational problems. We present the results of numerical modeling illustrating prime factorization and finding the shortest path connected selected points on the mesh. We also present experimental data on the proof-of-the-concept experiment for the two-path device. The magnetic part consists of two waveguides made of single-crystal yttrium iron garnet Y3Fe2(FeO4)3 (YIG) films. Different phase shifts per delay line are achieved by adjusting the magnitude and direction of the bias magnetic field. The auto-oscillation signal changes the propagation path in the magnetic matrix depending on the position of the outer electric phase shifter. The power difference between the active and passive paths exceeds 40 dBm at room temperature. The described logic devices are robust, deterministic, and operate at room temperature. The number of possible paths increases factorial with the size of the mesh. It may be possible to encode information in paths and retrieve it using the external phase shifters and attenuators. Potentially, combinatorial logic devices may compete with quantum computers in functional throughput. Physical limits and constraints are also discussed.
An experimental study to measure oil recovery factor by chemical agents and carbon dioxide after waterflooding
Authors: Yang Guilin , Bai Yunyun , Song Yuanjuan , Metwally Ahmed Sayed M. , Mahmoud Omar
Published: June 2022

Development of tight formations would be one of the main priority for petroleum industries due to the enormous demand to the fossil fuels in various industries. In this paper, we provided a set of experiments on the generated foams by carbon dioxide (CO2) and nitrogen (N2), cyclic CO2 injection, water alternating gas injection (WAG), active carbonated water injection (coupling surfactant effects and carbonated water (CW)), and introducing the impact of active carbonated water alternating gas injection (combination of WAG and CW injection) after waterflooding. Carbon dioxide is more feasible than nitrogen, it can be mobilize more in the pore throats and provided higher oil recovery factor. Generated foam with CO2 has increased oil recovery factor about 32% while it’s about 28% for generated foam by N2. Moreover, according to the results of this study, the maximum oil recovery factor for active carbonated water alternating gas injection, active carbonated water injection, and water alternating gas injection measured 74%, 65%, and 48% respectively.
Trusting COVID-19 vaccines as individual and social goal
Authors: Falcone Rino , Ansani Alessandro , Colì Elisa , Marini Marco , Sapienza Alessandro , Castelfranchi Cristiano , Paglieri Fabio
Published: June 2022

Trust in vaccines and in the institutions responsible for their management is a key asset in the global response to the COVID-19 pandemic. By means of a structured multi-scales survey based on the socio-cognitive model of trust, this study investigates the interplay of institutional trust, confidence in COVID-19 vaccines, information habits, personal motivations, and background beliefs on the pandemic in determining willingness to vaccinate in a sample of Italian respondents (N = 4096). We observe substantial trust in public institutions and a strong vaccination intention. Theory-driven structural equation analysis revealed what factors act as important predictors of willingness to vaccinate: trust in vaccine manufacturers (which in turn is supported by trust in regulators), collectivist goals, self-perceived knowledgeability, reliance on traditional media for information gathering, and trust in institutional and scientific sources. In contrast, vaccine hesitancy, while confined to a minority, is more prominent in less educated and less affluent respondents. These findings can inform institutional decisions on vaccine communication and vaccination campaigns.
Modelling the performance of an integrated fixed-film activated sludge (IFAS) system: a systematic approach to automated calibration
Authors: Pryce D. , Kapelan Z. , Memon F. A.
Published: June 2022

IFAS systems are inherently complex due to the hybrid use of both suspended and attached bacterial colonies for the purpose of pollutant degradation as part of wastewater treatment. This poses challenges when attempting to represent these systems mathematically due to the vast number of parameters involved. Besides becoming convoluted, large effort will be incurred during model calibration. This paper demonstrates a systematic approach to calibration of an IFAS process model that incorporates two sensitivity analyses to identify influential parameters and detect collinearity from a subset of 68 kinetic and stoichiometric parameters, and the use of the Nelder–Mead optimization algorithm to estimate the required values of these parameters. The model considers the removal of three critical pollutants including biochemical oxygen demand (BOD), total nitrogen (TN) and total suspended solids (TSS). Results from the sensitivity analyses identified four parameters that were the primary influence on the model. The model was found to be most sensitive to the two stoichiometric parameters including aerobic heterotrophic yield on soluble substrate whose total effects were responsible for 92.4% of the model’s BOD output sensitivity and 92.8% of the model’s TSS output sensitivity. The anoxic heterotrophic yield on soluble substrate was observed to be responsible for 54.3% of the model’s TN output sensitivity. To a lesser extent the two kinetic parameters, aerobic heterotrophic decay rate and reduction factor for denitrification on nitrite, were responsible for only 8.0% and 13.1% of the model’s BOD and TN output sensitivities respectively. Parameter estimation identified the need for only minor adjustments to default values in order to achieve sufficient accuracy of simulation with deviation from observed data to be only ± 3.6 mg/L, ± 1.3 mg/L, and ± 9.5 mg/L for BOD, TN and TSS respectively. Validation showed the model was limited in its capacity to predict system behaviour under extreme dissolved oxygen stress.
Dynamic interplay between the periplasmic chaperone SurA and the BAM complex in outer membrane protein folding
Authors: Schiffrin Bob , Machin Jonathan M. , Karamanos Theodoros K. , Zhuravleva Anastasia , Brockwell David J. , Radford Sheena E. , Calabrese Antonio N.
Published: June 2022

Correct folding of outer membrane proteins (OMPs) into the outer membrane of Gram-negative bacteria depends on delivery of unfolded OMPs to the β-barrel assembly machinery (BAM). How unfolded substrates are presented to BAM remains elusive, but the major OMP chaperone SurA is proposed to play a key role. Here, we have used hydrogen deuterium exchange mass spectrometry (HDX-MS), crosslinking, in vitro folding and binding assays and computational modelling to show that the core domain of SurA and one of its two PPIase domains are key to the SurA-BAM interaction and are required for maximal catalysis of OMP folding. We reveal that binding causes changes in BAM and SurA conformation and/or dynamics distal to the sites of binding, including at the BamA β1-β16 seam. We propose a model for OMP biogenesis in which SurA plays a crucial role in OMP delivery and primes BAM to accept substrates for folding.
Mansfieldite (AlAsO4·2H2O): a new white pigment in Himalayan artwork
Authors: Smith Gregory Dale , Hoevel Claire L. , Cavanagh Patrick D. , Druschel Gregory K.
Published: June 2022

This investigation reports the first ever identification of the mineral mansfieldite (AlAsO4·2H2O) as an artists’ white pigment. It was found in two 19th century thangkas that were ultimately traced to Chamdo, Tibet.
Efficient blue organic electrochemiluminescence luminophore based on a pyrenyl–phenanthroimidazole conjugate
Authors: Kim Kwang-Myeong , Kim Jiwoo , Kim Joohoon , Hong Jong-In
Published: June 2022

A pyrenyl–phenanthroimidazole conjugate exhibited strong blue electrochemiluminescence via the reductive–oxidation co-reactant pathway.
Cross-linkable carbazole-based hole transporting materials for perovskite solar cells
Authors: Daskeviciute-Geguziene Sarune , Magomedov Artiom , Daskeviciene Maryte , Genevičius Kristijonas , Nekrašas Nerijus , Jankauskas Vygintas , Kantminiene Kristina , McGehee Michael D. , Getautis Vytautas
Published: June 2022

Novel cross-linkable carbazole-based HTMs for inverted perovskite solar cells are designed with 16.9% power conversion efficiency and good stability.
Theoretical investigation of weak absorption and laser induced damage in YCOB crystals
Authors: Liu Jianfei , Wang Ji , Chen Yunlin
Published: June 2022

This paper introduces a method for studying weak absorption and laser-induced damage of YCOB crystals in terms of electron motion using the one-dimensional quantum waveguide theory.
Highly efficient blue quantum-dot light-emitting diodes based on a mixed composite of a carbazole donor and a triazine acceptor as the hole transport layer
Authors: Wang Dan , Huang Jia-Hui , Liu Hong-Liang , Peng Wen , Zou Shu-Hua , Miao Zi-Peng , Chen Xin-Man , Zhang Yong
Published: June 2022

Solution-processed thermally activated delayed fluorescence exciplex was employed as hole transport layer of blue quantum dot light-emitting diodes by blending 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine into poly(N-vinylcarbazole).
Dual promotional effect of CuxO clusters grown with atomic layer deposition on TiO2 for photocatalytic hydrogen production
Authors: Saedy Saeed , Hiemstra Nico , Benz Dominik , Van Bui Hao , Nolan Michael , van Ommen J. Ruud
Published: June 2022

The depletion zone formed around the CuxO clusters is the main photocatalytically active area, and the H2 production rate depends on surface coverage with this area; however, the overlap of these areas suppresses the photocatalyst activity.
Dealumination-controlled strategy mediates Ti–Y zeolite with cooperative active sites for selective oxidations
Authors: Lin Haoyi , Zhang Jiaxing , Duan Qingxu , Yang Kaixuan , Liao Weiping , Qi Shixue , Lü Hongying , Zhu Zhiguo
Published: June 2022

Hierarchical Ti–Y zeolite, with dual active sites containing framework-substituted Ti and tri-coordinated Al species, was successfully constructedviaa dealumination-controlled strategy, which synergistically catalyzed selective oxidations.
Removal of nanoparticles (both inorganic nanoparticles and nanoplastics) in drinking water treatment – coagulation/flocculation/sedimentation, and sand/granular activated carbon filtration
Authors: Hofman-Caris C. H. M. , Bäuerlein P. S. , Siegers W. G. , Mintenig S. M. , Messina R. , Dekker S. C. , Bertelkamp Ch. , Cornelissen E. R. , van Wezel A. P.
Published: June 2022

Nanoparticles, such as metallic ones like Ag, Au and TiO2 as well as nanoplastics, are applied in or emitted by a wide variety of products or stem from degradation.
Superprotonic conduction of intrinsically zwitterionic microporous polymers based on easy-to-make squaraine, croconaine and rhodizaine dyes
Authors: Taylor Dominic , Hu Xuanhe , Wu Can-Min , Tobin John M. , Oriou Zuzana , He Jun , Xu Zhengtao , Vilela Filipe
Published: June 2022

Porous organic polymers (POPs) have been prepared via a novel metal-free polycondensation between a tritopic indole-based monomer and squaric, croconic and rhodizonic acids.
Copper-doped carbon dots with enhanced Fenton reaction activity for rhodamine B degradation
Authors: Jin Zhiru , Li Qiuying , Tang Peiduo , Li Ganfeng , Liu Li , Chen Dong , Wu Ji , Chai Zhihui , Huang Gang , Chen Xing
Published: June 2022

CuCDs enhanced the Fenton reaction activity for rhodamine B degradation. Electron transfer happening on the surface of CuCDs and more ˙OH and 1O2 generation played vital roles in RhB degradation. RhB degradation filtrates exhibited low toxicity.
Designing anisotropic inorganic nanocapsules via self-assembly of polymer-like ultrathin Au nanowires
Authors: Li Xingyun , Zhang Sai , Chen Yuan , Wang Shanshan , Xu Qingchi , Xu Jun
Published: June 2022

By controlling the self-assembly conditions of polymer-like ultrathin Au nanowires, we successfully prepared a novel anisotropic hollow Au nanocapsule and used it as nano drug-carrier, which showed useful pH-responsive drug release behavior.
Confinement chemistry of FeOx centers for activating molecular oxygen under ambient conditions
Authors: Han Bingqi , Li Xinbo , Geng Zhibin , Li Liping , Li Guangshe
Published: June 2022

FeOx spatially confined in porous CeO2 induces an effective oxygen activation that improves CO preferential oxidation performance.
Periodically nanoporous hydrogen-bonded organic frameworks for high performance photocatalysis
Authors: Cheng Xiuyan , Zhang Jianling , Sha Yufei , Xu Mingzhao , Duan Ran , Su Zhuizhui , Li Jialiang , Wang Yanyue , Hu Jingyang , Guan Bo , Han Buxing
Published: June 2022

Here we demonstrate the construction of a periodically nanoporous hydrogen-bonded organic framework, which exhibits high performance for the photo-oxidative coupling of benzylamine under mild conditions.
Cp*CoIII-catalyzed formal [4 + 2] cycloaddition of 2-phenyl-1H-imidazoles to afford imidazo[1,2-c]quinazoline derivatives
Authors: Wu Deyu , Liu Zhengqiang , Chang Yiting , Chen Jiajing , Qi Haixiang , Dong Yi , Xu Heng
Published: June 2022

Cp*CoIII-catalyzed C–H amidation/annulation of 2-phenyl-1H-imidazoles with 1,4,2-dioxazol-5-ones were developed to give imidazo[1,2-c]quinazoline derivatives with broad substrate scope in moderate to good yields.
Electronically optimized diazirine-based polymer crosslinkers
Authors: Musolino Stefania F. , Mahbod Mahshid , Nazir Rashid , Bi Liting , Graham Hamish A. , Milani Abbas S. , Wulff Jeremy E.
Published: June 2022

Electronically optimized bis-diazirine crosslinkers allow aliphatic polymers to be crosslinked with up to 10-fold improved efficacy, relative to earlier designs. Activation is achieved using modest temperatures or through UV or visible light.
Photocatalytic hydrogen production and storage in carbon nanotubes: a first-principles study
Authors: Song Xiaohan , Bu Hongxia , Fan Yingcai , Wang Junru , Zhao Mingwen
Published: June 2022

The production and storage of hydrogen in CNNW/CNT core–shell structures via photocatalytic processes.
Bio-hybrid micro-swimmers propelled by flagella isolated from C. reinhardtii
Authors: Ahmad Raheel , Bae Albert J. , Su Yu-Jung , Pozveh Samira Goli , Bodenschatz Eberhard , Pumir Alain , Gholami Azam
Published: June 2022

Flagellum-based cargo propulsion. A bead attached to an isolated flagellum of C. reinhardtii is propelled along a helical path. (A) The time projection of axonemal shapes, (B) the track of the bead center.
Pediatric Feeding Disorder in Early Intervention: Expanding Access, Improving Outcomes, and Prioritizing Responsive Feeding
Authors: Cohen Stephanie C. , Dilfer Karen
Published: June 2022

Purpose:

Pediatric feeding disorder (PFD), like many childhood medical conditions, is likely to negatively impact a child's growth and development, daily learning opportunities, and family functioning. Parents who have children with a diagnosis of PFD may not yet know the most effective way to feed their children and often experience negative emotions surrounding mealtimes. These families may receive therapy services through early intervention (EI) programs. In many states, there are barriers that limit access to programs and provision of high-quality care for this population. These barriers include the lack of an approved single feeding-related diagnosis that renders a child automatically eligible, lack of approved stand-alone feeding-specific testing tools with which to determine eligibility, lack of educational and clinical experience requirements for providers, and considerable variation in service provision.

Method:

This clinical focus article reviews the definition of PFD, the multifaceted needs of families and children in EI, support for use of responsive feeding in treatment of PFD, alignment of responsive feeding strategies with EI principles, and barriers limiting access to consistent, high-quality EI services for children with PFD. Several changes to EI programs are proposed to address these barriers.

Conclusions:

Use of PFD as an automatically qualifying diagnosis for EI programs and use of approved stand-alone feeding-specific assessment tools could establish more consistent and specific eligibility standards for this population, likely expanding early access to support and improving outcomes. EI provider clinical experience and training requirements would likely lead to more consistent and high-quality, evidence-based service provision. Required training should include the use of methods such as routines-based intervention, parent coaching, and anticipatory guidance to support implementation of responsive feeding practices during mealtime routines.
Adaptive observer protocol designs for consensus tracking of multi‐agent systems
Authors: Chu Hongjun , Gorbachev Sergey , Yue Dong , Dou Chunxia , Ge Yuan
Published: June 2022

In this brief, a type of novel fully distributed adaptive protocols is designed for achieving leader‐follower multi‐agents tracking. The design procedure constitutes three steps. First, a local observer is constructed for each agent (including the leader) in virtue of its own inputs and outputs, aiming to estimating of that agent's state. Second, to propagate the estimate of the leader from target followers to all the followers, a distributed adaptive estimator is then proposed, via embedding with time‐varying coupling weights. At last, an elegant controller is designed for each follower based on the estimate of its own state and the estimate of the leader's state. The rigorous convergence analysis is provided. Finally, the simulation results validate the effectiveness of the proposed protocols.
Underwater localization using an optic and acoustic stereo imaging system for autonomous intervention robots
Authors: Park Jisung , Kim Jinwhan
Published: June 2022

Optical and acoustic stereo imaging has great potential for the precise and consistent localization of intervention underwater robots; however, it is still being explored due to its sensing limitations and various technical challenges. This study presents a novel localization method by combining an inertial navigation system and an optical and acoustic stereo imaging system. As a strategy for localization correction relative to underwater structures, the robot's pose is estimated based on a single acoustic image using a sonar simulator for mid‐range localization, and a robust visual tracking using a 3‐D wireframe model is employed for high‐precision localization near the target structures. The performance of the proposed technique was demonstrated through experimental validation using real data obtained from a test tank.
Low‐carbon generation expansion planning considering flexibility requirements for hosting wind energy
Authors: Pourmoosavi Mohammad‐Amin , Amraee Turaj
Published: June 2022

The operational flexibility of electric energy systems is one of the essential requirements for integrating a high share of renewable resources. The operational flexibility significantly impacts the mix of new power generation technologies. In this paper, a low‐carbon generation expansion planning (GEP) model is presented to investigate the impacts of flexibility requirements of power systems with a high share of wind energy. An improved clustered unit commitment (CUC) formulation is proposed to capture the flexibility limitation of thermal generating units fully. In this regard, clustered 10‐min ramp up/down limits for operational reserves, flexible‐ramp reserves, and contingency reserves, are introduced. The yearly variations of load and renewable generations preserving the chronological time correlations are included, considering 36 representative days obtained by the clustering approach. Besides, two types of BES devices are considered to investigate the role of BES in the provision of flexibility. The proposed flexible low‐carbon GEP model is formulated as a mixed‐integer programming model, and an optimal expansion plan is obtained using the CPLEX algorithm. By incorporating improved CUC formulation into the low‐carbon GEP model, more profound insight into power systems' flexibility requirement with high wind generation penetration is obtained.
New apparatus for the determination of liquid density at primary level in TUBITAK UME
Authors: Akcadag Umit Yuksel , Sariyerli Gokce Sevim
Published: June 2022

This work aimed to describe the new apparatus of TUBITAK UME for determining the density of liquids at the primary level by means of a hydrostatic weighing (HW) using a solid density standard. This new apparatus provides TUBITAK UME with the necessary infrastructure to certify reference liquids of density with adequate uncertainty to be used at a secondary level, such as for calibration of oscillation type density meters. The HWS produces reference values for liquids with different physical properties such as viscosity, surface tension and viscoelasticity in the case of non-Newtonian liquids. In this HWS, the automation of all mechanical parts such as loading/unloading of the reference weights and sinker, movement of bath, working of pump etc. took place. In this way, the primary level liquid density measurements were realized with uncertainities smaller than 0,01 kg/m3. The automation also effected the robustness of the system by providing the lower repeatability value and stabilization of temperature.
Early Diagnosis and Prevention of Infections in Cirrhosis
Authors: Kulkarni Anand V. , Premkumar Madhumita , Arab Juan P. , Kumar Karan , Sharma Mithun , Reddy Nageshwar D. , Padaki Nagaraja R. , Reddy Rajender K.
Published: June 2022

Strategies to prevent infection and improve outcomes in patients with cirrhosis. HAV, hepatitis A virus; HBV, hepatitis B virus; COVID-19, novel coronavirus disease 2019; NSBB, nonselective β-blocker; PPI, proton pump inhibitors.

Cirrhosis is a risk factor for infections. Majority of hospital admissions in patients with cirrhosis are due to infections. Sepsis is an immunological response to an infectious process that leads to end-organ dysfunction and death. Preventing infections may avoid the downstream complications, and early diagnosis of infections may improve the outcomes. In this review, we discuss the pathogenesis, diagnosis, and biomarkers of infection; the incremental preventive strategies for infections and sepsi; and the consequent organ failures in cirrhosis. Strategies for primary prevention include reducing gut translocation by selective intestinal decontamination, avoiding unnecessary proton pump inhibitors' use, appropriate use of β-blockers, and vaccinations for viral diseases including novel coronavirus disease 2019. Secondary prevention includes early diagnosis and a timely and judicious use of antibiotics to prevent organ dysfunction. Organ failure support constitutes tertiary intervention in cirrhosis. In conclusion, infections in cirrhosis are potentially preventable with appropriate care strategies to then enable improved outcomes.
Bifunctional Ionic Liquid Catalyzed Multicomponent Arylsulfonation of Phenols with Aryl Triazenes and DABSO for the Synthesis of Diaryl Sulfones
Authors: Zhang Yonghong , Liu Chenjiang , Tang Chengzong , Zhou Xinlei , Wang Bin , Jin Weiwei , Xia Yu
Published: June 2022

The bifunctional Lewis acidic ionic liquid (LAIL) catalyzed multicomponent arylsulfonation of phenols with aryl triazenes and DABSO was developed. By using LAILs as redox and Lewis acidic catalysts without any additional promoter or ligand through an N2 extrusion/SO2 insertion sequence, various aryl triazenes were transformed into aryl sulfonyl radicals by coupling with DABSO, and these were then coupled with phenoxy radicals to afford the corresponding diaryl sulfones in good yields. The good functional-group tolerance, gram-scale reaction, and avoidance of the use of SO2 gas further demonstrated the practicality of this arylsulfonation reaction.
Synthesis and Antiproliferative Activity of Novel Quercetin-1,2,3-Triazole Hybrids using the 1,3-Dipolar Cycloaddition (Click) Reaction
Authors: Carreiro Elisabete P. , Gastalho Carlos M. , Ernesto Sofia , Costa Ana R. , Antunes Célia M. , Burke Anthony J.
Published: June 2022

Twenty-three new quercetin-1,2,3-triazole hybrids were synthesized in good to quantitative yields via Cu(I)-catalyzed azide-alkyne cycloaddition reaction under microwave irradiation. These new hybrids contain a 1,4-disubstituted 1,2,3-triazole ring at the 3-OH position of quercetin whilst the remaining hydroxyl groups were either protected as methyl or benzyl groups or left unprotected. All the quercetin-1,2,3-triazole hybrids I–IV were evaluated against REM-134 canine mammary cancer cell line, which is used as a translational model for human breast cancer. These new analogues exhibit potent antiproliferative activity against this cancer cell line. Furthermore, the results show that some of the new quercetin-1,2,3-triazole hybrids have better activity than quercetin. Our best inhibitors displayed IC50 values in the range of 41–180 nM, and undoubtedly will have an important impact on the treatment of both canine and human breast cancer.
Quantized point vortex equilibria in a one-way interaction model with a Liouville-type background vorticity on a curved torus
Authors: Sakajo Takashi , Krishnamurthy Vikas S.
Published: June 2022

We construct point vortex equilibria with strengths quantized by multiples of 2π in a fixed background vorticity field on the surface of a curved torus. The background vorticity consists of two terms: first, a term exponentially related to the stream function and a second term arising from the curvature of the torus, which leads to a Liouville-type equation for the stream function. By using a stereographic projection of the torus onto an annulus in a complex plane, the Liouville-type equation admits a class of exact solutions, given in terms of a loxodromic function on the annulus. We show that appropriate choices of the loxodromic function in the solution lead to stationary vortex patterns with 4n̂ point vortices of identical strengths, n̂∈N. The quantized point vortices are stationary in the sense that they are equilibria of a “one-way interaction” model where the evolution of point vortices is subject to the continuous background vorticity, while the background vorticity distribution is not affected by the velocity field induced by the point vortices. By choosing loxodromic functions continuously dependent on a parameter and taking appropriate limits with respect to this parameter, we show that there are solutions with inhomogeneous point vortex strengths, in which the exponential part of the background vorticity disappears. The point vortices are always located at the innermost and outermost rings of the torus owing to the curvature effects. The topological features of the streamlines are found to change as the modulus of the torus changes.
Unsteady vortex flows around a hemisphere—cylinder body with turbulent separation
Authors: Ijaz Hamdoon , Ma Bao-Feng
Published: June 2022

Previous studies have revealed that vortex oscillations exist around slender bodies at low Reynolds numbers where the boundary layers undergo laminar separation. This investigation aims to extend the study to higher Reynolds numbers where the boundary layers exhibit turbulent separation. A hemisphere–cylinder body with a fineness ratio of 24.5 was numerically simulated using detached eddy simulation at angles of attack (AOAs) of 30°–80° and was analyzed using dynamic mode decomposition (DMD). The fineness ratio is the ratio of length to diameter of the cylinder. The Reynolds number based on the cylinder diameter is fixed at Re = 3.0 × 106. The results indicate that, at AOA < 45°, the downstream wake vortices around the slender body exhibit weak oscillations in phase, corresponding to symmetric modes, which is much different from the cases with laminar separation in the previous studies. At AOA > 45°, the vortex flow over the slender body is divided into two parts: forebody vortex oscillations with lower frequencies and shedding of afterbody vortices with higher frequencies. The vortex oscillations produce greater sectional side-force than the vortex shedding, and the associated flow structures are similar to the laminar case, although the separation points in this case are greatly delayed due to turbulent separation. The DMD results at a typical AOA of 50° show that the leading oscillatory mode is antisymmetric, corresponding to alternate vortex oscillation over the forebody; apparent interactions exist between the vortex oscillation and vortex shedding. The vortex shedding region moves forward toward the nose with increasing AOAs. In addition, at the AOAs of 50°–80°, the non-dimensional frequencies for the vortex shedding can be approximately collapsed into a linear relationship with respect to axial location of the afterbody cylinder if the crossflow velocities normal to the cylinder are employed to normalize the frequencies. The vortex-oscillation frequencies, however, are independent of the crossflow velocities, and no suitable scale was found to collapse the data at present.
A finite difference scheme for non-Cartesian mesh: Applications to rarefied gas flows
Authors: Modi Atharva , Rana Anirudh Singh
Published: June 2022

A novel numerical scheme based on the finite-difference framework is developed, which allows us to model moderately rarefied gas flows in irregular geometries. The major hurdle in constructing numerical methods for rarefied gas flows is the prescription of the velocity-slip and temperature-jump boundary conditions as well as the discretization of an intricate set of partial differential equations. The proposed scheme is demonstrated to solve the non-linear coupled constitutive relations model along with the corresponding non-linear slip and jump boundary conditions. The computation of the discretized weights is proposed using two approaches: (i) polynomial shape functions and (ii) a generalized inverse distance approach. The non-linear terms are discretized using the fixed-point iteration method. The numerical method is validated for the Laplace equation over an annulus, and results are presented for a lid-driven curved cavity and a triangular lid-driven cavity, which delineates its performance on a skewed non-Cartesian grid. The results are validated with direct simulation Monte Carlo data from the literature, and a robust convergence for the solutions is demonstrated.
Cesium acetate-assisted crystallization for high-performance inverted CsPbI3 perovskite solar cells
Authors: Li Tiantian , Wu Yue , Liu Zhou , Yang Yuanbo , Luo Haowen , Li Ludong , Chen Peng , Gao Xueping , Tan Hairen
Published: June 2022

Efficient inverted (p–i–n) type CsPbI3 perovskite solar cells (PSCs) have revealed promising applications due to their excellent thermal and photostability. Regulating the nucleation and crystallization of perovskite film is an important route to improving the performance of CsPbI3 PSCs. Herein, we explored cesium acetate (CsAc) as additive to manipulate the crystallization process of CsPbI3 perovskite films. By involving in the intermediate phase DMA1-x
Cs
x
PbI3-y
Ac
y
of perovskite, the pseudo-halide acetate (Ac−) can retard the ion exchange reaction between DMA+ and Cs+, leading to a perovskite with dense morphology, low defect density, and a long carrier lifetime. As a result, the optimal CsPbI3 PSCs yielded a high power conversion efficiency of 18.3%. Moreover, the encapsulated devices showed excellent operational stability and the devices retained their initial performance following 500 h of operation at the maximum power point under one-sun illumination in ambient conditions.
Stable and tunable multi-wavelength erbium-doped fiber lasers using saturable absorbent tungsten disulfide
Authors: Jiang Qiuhao , Li Peng , Tong Zhengrong , Zhang Weihua , Wang Xue , Yan Gangxiao
Published: June 2022

A multi-wavelength erbium-doped fiber laser using tungsten disulfide (WS2) as a nonlinear saturable absorber is proposed. The laser structure consists of a Lyot filter and a WS2 film in a ring cavity. The WS2 film attached to the end of the fiber jumper can suppress the mode competition phenomenon caused by erbium-doped fiber due to its good nonlinear optical properties. In addition, it can suppress mode contention and stabilize multi-wavelength output. The number of wavelengths can be tuned by adjusting the length of the polarization-maintaining fiber (PMF). In the Lyot filter, the PMF of 4, 8 and 12 m excite 5, 9 and 13 wavelengths with 1.38, 0.7 and 0.42 nm intervals, respectively. The experimental results show that in the range of 1528–1536 nm, the side-mode suppression ratio is 42 dB. After 60 min of continuous excitation, the output wavelength of the structure remains stabilization. It can be used as a light source in distributed sensing and wavelength division multiplexing systems.
Coexisting lattice contractions and expansions with decreasing thicknesses of Cu (100) nano-films
Authors: An Simin , Gao Xingyu , Zhang Xian , Chen Xin , Xian Jiawei , Liu Yu , Sun Bo , Liu Haifeng , Song Haifeng
Published: June 2022

Lattice parameters are a basic quantity in material characterization, and a slight alteration in lattice parameters directly affects the properties of materials. However, there are still considerable controversies as to whether lattice expansion or contraction occurs in metallic nanomaterials with size reduction. Here, the size dependences of the lattice parameter and surface free energy of clean Cu (100) films are investigated via simulations. Lattice parameters of the exposed surfaces contract, whereas lattice expansion occurs along the direction perpendicular to the surfaces with decreasing film thicknesses. This is striking since the metallic bonds usually lack strong directionality, and it is always regarded that the lattice variations in all directions are consistent. The contraction parallel to the surface is more severe than the expansion perpendicular to the surface in films. The lattices change from cubic to tetragonal with decreasing film thickness. Consequently, common contractions and occasional expansions of the lattice parameters of Cu nanoparticles have been observed in previous experiments. Increasing free energy and surface free energy with decreasing thicknesses is the thermodynamic origin of the lattice variations. Our study therefore provides a comprehensive physical basis for the surface effects on the lattice variations.
Ultra-intense laser-accelerated ion beams for high-gain inertial fusion: the effect of the ion mass on the beam properties
Authors: Badziak Jan , Domański Jarosław
Published: June 2022

This paper presents the results of detailed numerical studies of the properties of ion beams generated by a laser from targets with various atomic numbers under conditions relevant for ion fast ignition (IFI) of inertial fusion. The interaction of a 200 kJ 1 ps infrared (1.05 μm) laser with Li, C, Al, Ti, Cu and CH2 flat targets with the same areal mass density was numerically simulated using an advanced 2D3V particle-in-cell code. For each target, a set of ion beam characteristics important for IFI was determined. A detailed quantitative comparison of the IFI-relevant parameters of Li, C, Al, Ti and Cu ion beams and the proton beam (from the CH2 target) was made. The laser-accelerated Cu ion beam was found to achieve significantly higher values of beam intensity, fluence and ‘useful’ energy (for IFI), having a smaller angular divergence and a narrower energy spectrum than the beam of light ions or protons. Thus, it is shown for the first time that laser-accelerated heavy ion beams can achieve IFI-relevant parameters higher than light ion or proton beams and can potentially meet IFI requirements.
Analysis of the causes of undesirable curvature of the workpiece during longitudinal rolling using numerical simulation
Authors: Benešová S , Burdová Karolína , Hajšman J
Published: June 2022

Undesirable additional deformation was observed during the experimental cold rolling of steel. A simulation was performed in Deform software to clarify the causes. The influence of the unequal coefficient of friction, geometric inaccuracies of the rolls and the conveyor, and the situation when the rolls did not have the same diameter or rotated at different speeds were investigated. Simulations with different roll speeds corresponded best to reality. The simulation of the undesired curvature of the workpiece at different speeds of rotation of the rolls and 30% reduction was subsequently performed as an elastoplastic problem in order to determine the amount of springback and residual stress. Furthermore, the press straightening of the workpiece was simulated. Inhomogeneous and accidental deformation and residual stresses must be taken into account, especially when researching the effect of cold rolling on the mechanical properties and structure of the material.
Ballistic Resistance of ARMOX Advance according to NATO standard AEP-55 STANAG 4569
Authors: Coufal V , Křesťan J , Vnouček M
Published: June 2022

ARMOX low-alloy high-strength steel sheet is used, among other things, as a basic homogeneous ballistic protection in plate carriers and vehicle bodies. The hardest armour plates of the ARMOX series include ARMOX Advance, which, even with a smaller thickness, provides the same ballistic protection as the stronger ARMOX 500 or ARMOX 600 sheets. The manufacturer of ARMOX armour plates declares for the ARMOX Advance with a thickness of 5 mm the resistance to small arms fire with 7.62x51 and 5.56x45 rounds according to NATO AEP-55 STANAG 4569 Annex A level 1 and for the thickness of 7 mm the ballistic resistance to small arms fire with 7.62x39 API BZ rounds according to NATO AEP-55 STANAG 4569 Annex A level 2. Due to the manufactured thicknesses, ballistic resistance is not specified for levels 3 to 6 in accordance with NATO AEP-55 STANAG 4569 Annex A. For levels 1 to 3, STANAG 4569 does not require a test against flying fragments from 155 mm artillery shells, but it is an optional component at the discretion of the national authority. In order to be able to use this type of sheet for this purpose, empirical equations were used to determine whether the conditions set out in STANAG 4569 Annex A Level 1 and Level 2 are met over the full range of ballistic resistance required. From the results obtained it was found that the ballistic resistance of ARMOX Advance armour plate against flying artillery shell fragments is not met and therefore it cannot be used alone as a basic homogeneous ballistic protection in vehicle bodies and protective sheet carriers to provide protection of persons in areas where artillery fire is expected.
Effect of Heat Treatment Before and After Incremental Rolling on the Mechanical Properties of Titanium-Stabilized Austenitic Stainless Steel
Authors: Jirková H , Janda T , Opatová K , Říha J , Růžička J , Bublíková D , Volák J
Published: June 2022

Austenitic stainless steel 08Ch18N10T stabilised with titanium is used for parts of VVER nuclear power reactors. The final mechanical properties are strongly affected by the previous processing history. This is mainly due to the deformation hardening that is incorporated into the material during the production of semi-finished products. The experimental program was performed on 08Ch18N10T steel bars with a diameter of 30 mm. Incremental rolling was performed on bars that remained in the delivered condition and on bars subjected to solution annealing at 1020 °C for 60 minutes before rolling. The rolled bars were stabilised annealed at different temperatures. Then a metallographic evaluation and a tensile test at RT and 350 °C were performed. The results show that the rolling speed significantly affects the mechanical properties after stabilisation annealing. By reducing the rolling speed, it was possible in some cases to increase the yield strength up to 349 MPa. The stabilisation annealing temperature of 720 ° C with a holding time of 10 hours was evaluated as the most advantageous. In the case of higher stabilisation annealing temperatures, the lowest rolling speed, i.e. 25 rpm, had to be performed to achieve higher hot yield strength values exceeding 177 MPa.
Options for Implementing Additive Manufacturing Technologies into a Foundry for Small Castings
Authors: Votava F , Bricín D
Published: June 2022

This paper is focused on the possibility of the implementing various additive manufacturing technologies into the investment casting process. The most frequently used AM technologies were employed to print fusible models of valves for musical instruments. This was done to accelerate the production process of new products in the foundry. The output of the work should determine the optimal AM technology according to the quality of surface and shape for creating a fusible model and suitable materials should also be recommended. Furthermore, the financial aspects of the variants were evaluated. For this evaluation, the analyses of the ash content, visual inspection, surface roughness and topography of the printed models were done. After these analyses, the models were formed, moulds were fired and the tin alloy was cast. Castings were subjected to the same analyses as for the models. X-ray inspection was done and finally the defects of the castings were evaluated.
Prediction of defects of ductile iron casting by numerical simulation
Authors: Socha L , Gryc K , Sviželová J , Chmiel M , Brathová M , Filipek S
Published: June 2022

Conditions favourable for the development of internal defects in cast pieces may occur in the course of ductile iron casting. The presence of such defects may be fatal for the castings and, together with other factors, result in their disposal. Therefore, any defects should be revealed as early as in the casting design phase if possible. This can be achieved through numerical simulations, a tool commonly used today to predict defects. This paper describes the procedure of numerical modelling of ductile iron casting and solidification of castings intended for the power industry. The purpose of our numerical simulations was to predict filling, solidification and stress states in order to verify whether the proposed production technology is adequate. The numerical simulations revealed some minor deficiencies in the production technology which might lead to defects should an unexpected change in the process conditions occur. In particular, these defects concerned the inlet system, risers, and susceptibility to cracking. Measures to eliminate the risks associated with development of the above-mentioned defects were proposed based on the simulations, which will be integrated in the production technology.
Testing of wear properties of inserts made from semi-solid processed experimental steel
Authors: Opatová K , Zatloukal T , Jirková H , Volkmanová J
Published: June 2022

To reduce the cost of manufacturing tools, which are commonly made from powder steels, high-alloy tool steel in the form of an ingot was cast. Conventional casting allows better use of recycled materials and an overall reduction in material production costs. This experimental steel was then processed in a semi-solid state to remove the unsuitable casting structure and to obtain the desired functional properties. In the case of tools, it is primarily a sufficient toughness and abrasion resistance. To determine the wear resistance of the experimental steel, replaceable inserts for machining tests were made. The inserts were prepared by electro-erosive machining. During testing, the geometry of the insert was optimized to achieve good chip evacuation and other cutting properties. Wear was measured using a digital microscope and at the same time, the roughness of the workpiece was measured. For comparison, a powder steel insert of the corresponding chemical composition was also produced, which has the commercial title Böhler K390 Microclean. This steel was heat-treated according to the manufacturer's recommendations. By comparing the results obtained on experimental cast steel and commercially produced powder steel, it was found that cast steel processed by semi-solid technology achieves three times lower cutting-edge wear during machining than powder steel.
Usage of the 3D printed model for the forming during the development of the casting mould
Authors: Korinek Jiri , Raz Karel , Chval Zdenek
Published: June 2022

This paper deals with the usage of the plastic model (created by additive technology), which can be used for the mould production as an internal model for the cavity. This mould is intended for the steel casting technology. The particular plastic model is created by the conventional 3D printer HP Multi Jet Fusion 4200 from the material PA 12 GB. It is polyamide with 40% of glass filling. This material is suitable for this method because of good mechanical properties. The creating of the steel casting mould has some specification which are deeply described in this paper. The comparing of several dimensions between the CAD model, plastic model and the final casted model from steel is performed here. It is obvious that the differences and tolerances are less than 1%. This approach can be used as a replacement of the wood models which are generally used. The benefits of the 3D printed model are higher accuracy of the model, higher complexity of the model and production time which can be less than 3 days (from the CAD model to the plastic model for the casting mould, but depending on complexity and size of the model).
Highly-stable generation of vector beams through a common-path interferometer and a DMD
Authors: Perez-Garcia Benjamin , Mecillas-Hernández Francisco I , Rosales-Guzmán Carmelo
Published: June 2022

Complex vector modes of light, non-separable in their spatial and polarisation degrees of freedom, are revolutionising a wide variety of research fields. It is therefore not surprising that the generation techniques have evolved quite dramatically since their inception. At present it is common to use computer-controlled devices, among which digital micromirror devices have become popular. Some of the reason for this are their low-cost, their polarisation-insensitive and their high-refresh rates. As such, in this manuscript we put forward a novel technique characterised by its high stability, which is achieved through a common-path interferometer. We demonstrate the capabilities of this technique experimentally, first by generating arbitrary vector modes on a higher-order Poincaré sphere, secondly, by generating vector modes in different coordinates systems and finally, by generating various vector modes simultaneously. Our technique will find applications in fields such as optical manipulations, optical communications, optical metrology, among others.