bluuebunny/crossref_metadata_2025_split huggingface dataset:
A fluid-driven soft robotic fish inspired by fish muscle architecture
Authors: Liu Sijia , Wang Yingjie , Li Zhennan , Jin Miao , Ren Lei , Liu Chunbao 
Published: January 2022

Abstract
Artificial fish-like robots developed to date often focus on the external morphology of fish and have rarely addressed the contribution of the structure and morphology of biological muscle. However, biological studies have proven that fish utilize the contraction of muscle fibers to drive the protective flexible connective tissue to swim. This paper introduces a pneumatic silicone structure prototype inspired by the red muscle system of fish and applies it to the fish-like robot named Flexi-Tuna. The key innovation is to make the fluid-driven units simulate the red muscle fiber bundles of fish and embed them into a flexible tuna-like matrix. The driving units act as muscle fibers to generate active contraction force, and the flexible matrix as connective tissue to generate passive deformation. Applying alternant pressure to the driving units can produce a bending moment, causing the tail to swing. As a result, the structural design of Flexi-Tuna has excellent bearing capacity compared with the traditional cavity-type and keeps the body smooth. On this basis, a general method is proposed for modeling the fish-like robot based on the independent analysis of the active and passive body, providing a foundation for Flexi-Tuna’s size design. Followed by the robot’s static and underwater dynamic tests, we used finite element static analysis and fluid numerical simulation to compare the results. The experimental results showed that the maximum swing angle of the tuna-like robot reached 20°, and the maximum thrust reached 0.185 N at the optimum frequency of 3.5 Hz. In this study, we designed a unique system that matches the functional level of biological muscles. As a result, we realized the application of fluid-driven artificial muscle to bionic fish and expanded new ideas for the structural design of flexible bionic fish.
A recent weakening of winter temperature association between Arctic and Asia
Authors: Wu Bingyi , Li Zhenkun , Francis Jennifer A , Ding Shuoyi 
Published: January 2022

Abstract
Arctic warming and its association with the mid-latitudes has been a hot topic over the past two decades. Although many studies have explored these issues, it is not clear how their linkage has changed over time. The results show that winter low tropospheric temperatures in Asia experienced two phases over the past two decades. Phase I (2007/2008–2012/2013) was characterized by a warm Arctic and cold Eurasia, and phase II by a warm Arctic and warm Eurasia (2013/2014–2018/2019). A strengthened association in winter temperature between the Arctic and Asia occurred during phase I, followed by a weakened linkage during phase II. Simulation experiments forced by observed Arctic sea ice variability largely reproduce observed patterns, suggesting that Arctic sea ice loss contributes to phasic (or low-frequency) variations in winter atmosphere and makes the Arctic–Asia temperature association fluctuate over time. The weakening of the Arctic–Asia linkage post-2012/2013 was associated with amplified and expanded Arctic warming. The corresponding anomalies in sea level pressure resembled a positive-phase North Atlantic Oscillation during phase II. This study implies that the phasic warm Arctic—cold Eurasia and warm Arctic—warm Eurasia patterns would alternately happen in the context of Arctic sea ice loss, which increases the difficulty in correctly predicting Asian winter temperature.
How community forest management performs when REDD+ payments fail
Authors: Collins Amy C , Grote Mark N , Caro Tim , Ghosh Aniruddha , Thorne James , Salerno Jonathan , Mulder Monique Borgerhoff 
Published: January 2022

Abstract
The reduced emissions in deforestation and degradation (REDD+) initiative uses payments for ecosystem services as incentives for developing countries to manage and protect their forests. REDD+ initiatives also prioritize social (and environmental) co-benefits aimed at improving the livelihoods of communities that are dependent on forests. Despite the incorporation of co-benefits into REDD+ goals, carbon sequestration remains the primary metric for which countries can receive payments from REDD+, but after more than 10 years of REDD+, many site-specific programs have failed to complete the carbon verification process. Here, we examine whether the REDD+ social co-benefits alone are sufficient to have slowed deforestation in the absence of carbon payments on Pemba, Tanzania. Using satellite imagery (Landsat archive), we quantified forest cover change for the period before (2001–2010) and after (2010–2018) the launch in 2010–2011 of Pemba island’s REDD+ readiness project. We then compared rates of forest cover change between shehia (administrative units) that were part of REDD+ readiness intervention and those that were not, adjusting for confounding variables and the non-random selection of REDD+ shehia with a statistical matching procedure. Despite considerable variation in forest outcomes among shehia, the associated co-benefits with the Pemba REDD+ project had no discernible effect on forest cover change. Likewise, we did not detect an effect of socioecological covariates on forest cover change across all shehia, though island-wide human population growth since 2012 may have played a role. These findings are unsurprising given the failure to secure carbon payments on Pemba and indicate that co-benefits alone are insufficient to reduce deforestation. We conclude that better oversight of all-involved parties is needed to ensure that REDD+ interventions satisfactorily conclude the process of securing a mechanism for carbon payments, if slowing deforestation is to be achieved.
Classification of four qubit states and their stabilisers under SLOCC operations
Authors: Dietrich Heiko , de Graaf Willem A. , Marrani Alessio , Origlia Marcos 
Published: January 2022

Abstract
We classify four qubit states under SLOCC operations, that is, we classify the orbits of the group

S
L

(

2
,
C

)

4

on the Hilbert space

H

4

=

(

C

2

)

⊗
4

. We approach the classification by realising this representation as a symmetric space of maximal rank. We first describe general methods for classifying the orbits of such a space. We then apply these methods to obtain the orbits in our special case, resulting in a complete and irredundant classification of

S
L

(

2
,
C

)

4

-orbits on

H

4

. It follows that an element of

(

C

2

)

⊗
4

is conjugate to an element of precisely 87 classes of elements. Each of these classes either consists of one element or of a parameterised family of elements, and the elements in the same class all have equal stabiliser in

S
L

(

2
,
C

)

4

. We also present a complete and irredundant classification of elements and stabilisers up to the action of

S
y
m

4

⋉
S
L

(

2
,
C

)

4

where Sym4 permutes the four tensor factors of

(

C

2

)

⊗
4

.
Chaos in a deformed Dicke model
Authors: L Corps Ángel , Molina Rafael A , Relaño Armando 
Published: January 2022

Abstract
The critical behavior in an important class of excited state quantum phase transitions is signaled by the presence of a new constant of motion only at one side of the critical energy. We study the impact of this phenomenon in the development of chaos in a modified version of the paradigmatic Dicke model of quantum optics, in which a perturbation is added that breaks the parity symmetry. Two asymmetric energy wells appear in the semiclassical limit of the model, whose consequences are studied both in the classical and in the quantum cases. Classically, Poincaré sections reveal that the degree of chaos not only depends on the energy of the initial condition chosen, but also on the particular energy well structure of the model. In the quantum case, Peres lattices of physical observables show that the appearance of chaos critically depends on the quantum conserved number provided by this constant of motion. The conservation law defined by this constant is shown to allow for the coexistence between chaos and regularity at the same energy. We further analyze the onset of chaos in relation with an additional conserved quantity that the model can exhibit.
Large Eddy simulation of tracer gas dispersion in a cavity
Authors: McMullan W A 
Published: January 2022

Abstract
This paper assesses the prediction of inert tracer gas dispersion within a cavity of height (H) 1.0 m, and unity aspect ratio, using large Eddy simulation (LES). The flow Reynolds number was 67 000, based on the freestream velocity and cavity height. The flow upstream of the cavity was laminar, producing a cavity shear layer which underwent a transition to turbulence over the cavity. Three distinct meshes are used, with grid spacings of

H

/

100

(coarse),

H

/

200

(intermediate), and

H

/

400

(fine) respectively. The Smagorinsky, WALE, and Germano-Lilly subgrid-scale models are used on each grid to quantify the effects of subgrid-scale modelling on the simulated flow. Coarsening the grid led to small changes in the predicted velocity field, and to substantial over-prediction of the tracer gas concentration statistics. Quantitative metric analysis of the tracer gas statistics showed that the coarse grid simulations yielded results outside of acceptable tolerances, while the intermediate and fine grids produced acceptable output. Interrogation of the fluid dynamics present in each simulation showed that the evolution of the cavity shear layer is heavily influenced by the grid and subgrid scale model. On the coarse and intermediate grids the development of the shear layer is delayed, inhibiting the entrainment and mixing of the tracer gas into the shear layer, reducing the removal of the tracer gas from the cavity. On the fine grid, the shear layer developed more rapidly, resulting in enhanced removal of the tracer gas from the cavity. Concentration probability density functions showed that the fine grid simulations accurately predicted the range, and the most probable value, of the tracer gas concentration towards both walls of the cavity. The results presented in this paper show that the WALE and Germano-Lilly models may be advantageous over the standard Smagorinsky model for simulations of pollutant dispersion in the urban environment.
Plasmonic excitations in two-dimensional materials: effects of structural symmetry and material anisotropy
Authors: Ding Linhui , Wang Ningning , Chen Leiming , Han Kui , Shen Xiaopeng , Wang Weihua 
Published: January 2022

Abstract
Plasmonics in two-dimensional (2D) materials, an emerging direction of nano-optics, has attracted great attention recently, which exhibits unique properties than that in noble metals. Extending its advanced features by different manipulations is very beneficial for its promotion. In this paper, we study plasmonic excitations in graphene and black phosphorus (BP) nanostructures, where the effects of structural symmetry and material anisotropy are discussed. We show that the two factors are crucial to mode excitations, e.g. the extinction can be dominated by higher order modes rather than dipole resonance. The behavior occurs only in the direction hosting larger resonance frequencies, e.g. armchair (AC) direction of BP and shorter side of graphene rectangles. In BP rectangles along AC direction, the two factors are competing, and thus can be applied cooperatively to tune plasmonic resonance, from dipole to higher order excitations. Besides, the manipulation can also be achieved by designing BP square rings, in which the interaction between outer and inner edges show great impact on mode excitations. Our studies further promote the understanding of plasmonics in 2D materials, and will pave the way for particular plasmonic applications.
Optimal trap velocity in a dynamic holographic optical trap using a nematic liquid crystal spatial light modulator
Authors: Malik Karuna Sindhu , Boruah Bosanta R 
Published: January 2022

Abstract
A dynamic holographic optical trap uses a dynamic diffractive optical element such as a liquid crystal spatial light modulator to realize one or more optical traps with independent controls. Such holographic optical traps provide a number of flexibilities and conveniences useful in various applications. One key requirement for such a trap is the ability to move the trapped microscopic object from one point to the other with the optimal velocity. In this paper we develop a nematic liquid crystal spatial light modulator based holographic optical trap and experimentally investigate the optimal velocity feasible for trapped beads of different sizes, in such a trap. Our results show that the achievable velocity of the trapped bead is a function of size of the bead, step size, interval between two steps and power carried by the laser beam. We observe that the refresh rate of a nematic liquid crystal spatial light modulator is sufficient to achieve an optimal velocity approaching the theoretical limit in the respective holographic trap for beads with radius larger than the wavelength of light.
Designing spin-textured flat bands in twisted graphene multilayers via helimagnet encapsulation
Authors: Chen Guangze , Khosravian Maryam , Lado Jose L , Ramires Aline 
Published: January 2022

Abstract
Twisted graphene multilayers provide tunable platforms to engineer flat bands and exploit the associated strongly correlated physics. The two-dimensional nature of these systems makes them suitable for encapsulation by materials that break specific symmetries. In this context, recently discovered two-dimensional helimagnets, such as the multiferroic monolayer NiI2, are specially appealing for breaking time-reversal and inversion symmetries due to their nontrivial spin textures. Here we show that this spin texture can be imprinted on the electronic structure of twisted bilayer graphene by proximity effect. We discuss the dependence of the imprinted spin texture on the wave-vector of the helical structure, and on the strength of the effective local exchange field. Based on these results we discuss the nature of the superconducting instabilities that can take place in helimagnet encapsulated twisted bilayer graphene. Our results put forward helimagnetic encapsulation as a powerful way of designing spin-textured flat band systems, providing a starting point to engineer a new family of correlated moire states.
Research on low cycle fatigue life prediction considering average strain
Authors: Peng Yan , Liu Yang , Li Haoran , Xing Jiankang 
Published: January 2022

Abstract
To address the difficult problems in the study of the effect of average strain on fatigue life under low-cycle fatigue loads, the effect of average strain on the low-cycle fatigue life of materials under different strain cycle ratios was discussed based on the framework of damage mechanics and its irreversible thermodynamics. By introducing the Ramberg-Osgood cyclic constitutive equation, a new low-cycle fatigue life prediction method based on the intrinsic damage dissipation theory considering average strain was proposed, which revealed the correlation between low-cycle fatigue strain life , material properties, and average strain. Through the analysis of the low-cycle fatigue test data of five different metal materials, the model parameters of the corresponding materials were obtained. The calculation results indicate that the proposed life prediction method is in good agreement with the test, and a reasonable characterization of the low-cycle fatigue life under the influence of average strain is realized. Comparing calculations with three typical low-cycle fatigue life prediction models, the new method is within two times the error band, and the prediction effect is significantly better than the existing models, which is more suitable for low-cycle fatigue life prediction. The low-cycle fatigue life prediction of different cyclic strain ratios based on the critical region intrinsic damage dissipation power method provides a new idea for the research of low-cycle fatigue life prediction of metallic materials.
Fiducial visibility on planar images during motion-synchronized tomotherapy treatments
Authors: Ferris William S , DeWerd Larry A , Culberson Wesley S 
Published: January 2022

Abstract

Objective. Synchrony® is a motion management system on the Radixact® that uses planar kV radiographs to locate the target during treatment. The purpose of this work is to quantify the visibility of fiducials on these radiographs. Approach. A custom acrylic slab was machined to hold 8 gold fiducials of various lengths, diameters, and orientations with respect to the imaging axis. The slab was placed on the couch at the imaging isocenter and planar radiographs were acquired perpendicular to the custom slab with varying thicknesses of acrylic on each side. Fiducial signal to noise ratio (SNR) and detected fiducial position error in millimeters were quantified. Main Results. The minimum output protocol (100 kVp, 0.8 mAs) was sufficient to detect all fiducials on both Radixact configurations when the thickness of the phantom was 20 cm. However, no fiducials for any protocol were detected when the phantom was 50 cm thick. The algorithm accurately detected fiducials on the image when the SNR was larger than 4. The MV beam was observed to cause RFI artifacts on the kV images and to decrease SNR by an average of 10%. Significance. This work provides the first data on fiducial visibility on kV radiographs from Radixact Synchrony treatments. The Synchrony fiducial detection algorithm was determined to be very accurate when sufficient SNR is achieved. However, a higher output protocol may need to be added for use with larger patients. This work provided groundwork for investigating visibility of fiducial-free solid targets in future studies and provided a direct comparison of fiducial visibility on the two Radixact configurations, which will allow for intercomparison of results between configurations.
MHD instability at the cathode spot as the origin of the vortex formation in high-intensity plasma arcs
Authors: Barati Hadi , Kharicha Abdellah , Al-Nasser Mohamad , Kreuzer Daniel , Hackl Gernot , Gruber Markus , Ishmurzin Anton , Redl Christian , Teplyakov Igor O , Wu Menghuai , Ludwig Andreas 
Published: January 2022

Abstract
Magnetohydrodynamic instability in a high-intensity arc, similar to typical arcs in DC electric arc furnaces, is simulated using an induction based model under 2D axisymmetric conditions. Time-averaged results show a good agreement with steady-state calculated results expected for a stable arc. The transient results declare that z-pinch close to the cathode, occurring due to the high electrical current density, is responsible for arc instability in this region. The unstable behavior of the arc can be evaluated in a periodic procedure. Moreover, correlations between the fluctuations in total voltage drop curve and the arc shape are investigated: when the arc is in form of column (or bell) the total voltage drop is on a minimum peak; if there is an irregular expansion of the arc in form of arms, the total voltage drop shows a maximum peak.
Deterministic loading of a single strontium ion into a surface electrode trap using pulsed laser ablation
Authors: Osada Alto , Noguchi Atsushi 
Published: January 2022

Abstract
Trapped-ion quantum technologies have been developed for decades toward applications such as precision measurement, quantum communication and quantum computation. Coherent manipulation of ions’ oscillatory motions in an ion trap is important for quantum information processing by ions, however, unwanted decoherence caused by fluctuating electric-field environment often hinders stable and high-fidelity operations. One way to avoid this is to adopt pulsed laser ablation for ion loading, a loading method with significantly reduced pollution and heat production. Despite the usefulness of the ablation loading such as the compatibility with cryogenic environment, randomness of the number of loaded ions is still problematic in realistic applications where definite number of ions are preferably loaded with high probability. In this paper, we demonstrate an efficient loading of a single strontium ion into a surface electrode trap generated by laser ablation and successive photoionization. The probability of single-ion loading into a surface electrode trap is measured to be 82%, and such a deterministic single-ion loading allows for loading ions into the trap one-by-one. Our results open up a way to develop more functional ion-trap quantum devices by the clean, stable, and deterministic ion loading.
Infrastructure autopoiesis: requisite variety to engage complexity
Authors: Chester Mikhail V , Allenby Braden 
Published: January 2022

Abstract
Infrastructure systems must change to match the growing complexity of the environments they operate in. Yet the models of governance and the core technologies they rely on are structured around models of relative long-term stability that appear increasingly insufficient and even problematic. As the environments in which infrastructure function become more complex, infrastructure systems must adapt to develop a repertoire of responses sufficient to respond to the increasing variety of conditions and challenges. Whereas in the past infrastructure leadership and system design has emphasized organization strategies that primarily focus on exploitation (e.g., efficiency and production, amenable to conditions of stability), in the future they must create space for exploration, the innovation of what the organization is and does. They will need to create the abilities to maintain themselves in the face of growing complexity by creating the knowledge, processes, and technologies necessary to engage environment complexity. We refer to this capacity as infrastructure autopoiesis. In doing so infrastructure organizations should focus on four key tenets. First, a shift to sustained adaptation—perpetual change in the face of destabilizing conditions often marked by uncertainty—and away from rigid processes and technologies is necessary. Second, infrastructure organizations should pursue restructuring their bureaucracies to distribute more resources and decisionmaking capacity horizontally, across the organization’s hierarchy. Third, they should build capacity for horizon scanning, the process of systematically searching the environment for opportunities and threats. Fourth, they should emphasize loose fit design, the flexibility of assets to pivot function as the environment changes. The inability to engage with complexity can be expected to result in a decoupling between what our infrastructure systems can do and what we need them to do, and autopoietic capabilities may help close this gap by creating the conditions for a sufficient repertoire to emerge.