bluuebunny/crossref_metadata_2025 huggingface dataset:
The technology of shrimp larvae transportation: ecophysiology and bioeconomy effects on high stocking density shrimp	Litopenaeus vannamei
Authors: Saputra Henry Kasmanhadi , Hamka Muhammad Subhan , Kurniaji Ardana , Susanti Lily , Firman Sri Wahyuni , Dwiarto Agus , Alam Hilman Syaeful
Published: April 2022

Intensification is part of modern shrimp farming technology, feed, and high stocking density. High density could save time and production costs. This research aimed to determine the optimal tolerance of shrimp larvae with high stocking density per bag unit without oxygen liquid in terms of environmental physiology (ecophysiology) and economic feasibility aspects (bioeconomics). The shrimp larvae used were post-larvae 10 with a weight of 0.0026 ± 0.0021 g, which were previously fasted. The method used was a simulation of a three-hour trip with treatments: 200 larvae/packing (control), 400 larvae/packing, and 600 larvae/packing. The treatment for each packing was 450 ml of water and oxygen gas and added ice cubes in each styrofoam during delivery at night. The results showed that the stocking density of 600 larvae/packing had the best value. In terms of ecophysiology, the survival rate was highest when arriving at the location, with 98.20% of total larvae. The lowest oxygen consumption in the metabolic process was 0.76 ± 0.10 mg/L. Reviewing a bioeconomic, the potential profit per packing reaches IDR 995,528. It can be concluded that the use of oxygen gas and the addition of ice cubes in transportation increased the survival of shrimp larvae.
The Importance of Halal Certification for the Processed Food by SMEs to Increase Export Opportunities
Authors: Gayatri Anggarkasih Made , Sukmana Resma Prima
Published: April 2022

As the largest Muslim population country, Indonesia potentially becomes the largest exporter of halal food products globally, especially to OIC countries with demands for the fulfillment of halal product guarantees and food safety. Currently, BPJPH is assigned as the organizer of halal product guarantees in Indonesia, and MUI remains the party authorized to issue a fatwa on the determination of halalness. This fatwa will be submitted to BPJPH as the basis for issuing halal certificates. The halal certification and assurance systems designed and implemented by MUI have also been recognized and even adopted by halal certifier bodies abroad. Until 2019, only 0.11% of SMEs had halal certificates. Promoting halal certification for SMEs is an important strategy in increasing food exports. In addition, to the obligation to comply with Law number 33 of 2014 on Halal Products Guarantee (Law of JPH). Halal certification significantly enhances the marketability of SMEs products. This paper describes the importance of halal certification of processed foods to increase export opportunities and reviews the government's concrete steps in implementing the Halal Certification for SMEs.
Covid-19’s pandemic braking policies: a rise in generality of disorder to limit irreversibilities
Authors: Grossetti Michel
Published: April 2022

The Covid-19 epidemic generated a situation in which, in many countries, the health system could not handle the situation alone, leading governments to institute limitations on travel and social interaction. These measures led to a flurry of changes, temporary or more lasting, in social relations, forms of work, police surveillance, economic activities, education, food circuits … If one measures the generality of a phenomenon by the diversity of the spheres of activity affected, then lockdown is a rapid and massive rise in generality that can be considered a form of disorder. Just as a therapy used to preserve a patient's health can have side effects that are disorders in a patient’s body, so the measures to curb the epidemic have effects on various aspects of the social world. This analysis is supported by results from a survey conducted in France during the spring 2020 lockdown among more than 16,000 people, and then repeated in December 2020 and January 2021 among 3,620 people who responded to the first survey.
MCDM methods: Practical difficulties and future directions for improvement
Authors: Dhurkari Ram Kumar
Published: April 2022

This paper critically reviews practical difficulties inherent in some of the existing multi-criteria decision-making methods. The paper also emphasizes why a benchmark decision situation is essential in assessing the capabilities of any multi-criteria decision-making method. The capability is in terms of accuracy in modeling the human decision-making process. Most multi-criteria decision-making methods consist of two important steps. The first step involves elicitation of preferences from the decision-maker on various criteria and alternatives of the problem. In the second step, the preferences defined by the decision-maker are aggregated. The overall score generated after aggregation is used in rank order calculation and final selection. However, if the prescriptions of multi-criteria decision-making method do not resemble actual or real decision of the very same decision-maker, then multi-criteria decision-making method failed in either capturing the true preferences of the decision-maker or in aggregating these preferences as per the expectations of the decision-maker. This paper discusses some of the latest theories of decision-making and provides three important directions to improve the descriptive aspects of multi-criteria decision analysis.
Characterizing cell shape with a single number
Authors: McConnon Aili
Published: April 2022

Characterization of a cell shape and the best choice of cell descriptor depends on environmental conditions
Hirota-Miwa equations on a time space scale
Authors: Hovhannisyan Gro , Ruff Oliver
Published: April 2022

We derive a general time scale version of the Hirota–Miwa equation as a compatibility condition arising from a new version of a three-dimensional Lax system, construct its 3-soliton solutions, and consider various examples. We prove the invariance of the compatibility condition of the two-dimensional Lax system under a gauge transformation. The 3-soliton solution obtained here may be used in modeling in view of its variable graininess and a large number of free parameters.
High harmonic spectra computed using time-dependent Kohn–Sham theory with Gaussian orbitals and a complex absorbing potential
Authors: Zhu Ying , Herbert John M.
Published: April 2022

High harmonic spectra for H2 and H2+ are simulated by solving the time-dependent Kohn–Sham equation in the presence of a strong laser field using an atom-centered Gaussian representation of the density and a complex absorbing potential. The latter serves to mitigate artifacts associated with the finite extent of the basis functions, including spurious reflection of the outgoing electronic wave packet. Interference between the outgoing and reflected waves manifests as peak broadening in the spectrum as well as the appearance of spurious high-energy peaks after the harmonic progression has terminated. We demonstrate that well-resolved spectra can be obtained through the use of an atom-centered absorbing potential. As compared to grid-based algorithms, the present approach is more readily extensible to larger molecules.
The Cauchy problem for the Gurevich–Zybin system
Authors: Holmes J. , Thompson R. C. , Tiğlay F.
Published: April 2022

We consider the periodic Cauchy problem for the Gurevich–Zybin (GZ) system on the n-dimensional torus. The GZ system models dark matter as a collision-free gas in an expanding universe. We establish local in-time well-posedness for classical solutions in Sobolev spaces. Moreover, the local in-time result is extended to all time under additional assumptions. In particular, we consider three cosmological eras determined by the universal expansion parameter. In each era, global in-time existence is established if the initial density contrast is small and the rate of change of the initial velocity is sufficiently large.
Analytical approach to chiral active systems: Suppressed phase separation of interacting Brownian circle swimmers
Authors: Bickmann Jens , Bröker Stephan , Jeggle Julian , Wittkowski Raphael
Published: April 2022

We consider chirality in active systems by exemplarily studying the phase behavior of planar systems of interacting Brownian circle swimmers with a spherical shape. For this purpose, we derive a predictive field theory that is able to describe the collective dynamics of circle swimmers. The theory yields a mapping between circle swimmers and noncircling active Brownian particles and predicts that the angular propulsion of the particles leads to a suppression of their motility-induced phase separation, being in line with recent simulation results. In addition, the theory provides analytical expressions for the spinodal corresponding to the onset of motility-induced phase separation and the associated critical point as well as for their dependence on the angular propulsion of the circle swimmers. We confirm our findings by Brownian dynamics simulations. Agreement between results from theory and simulations is found to be good.
Theory of length-scale dependent relaxation moduli and stress fluctuations in glass-forming and viscoelastic liquids
Authors: Klochko L. , Baschnagel J. , Wittmer J. P. , Meyer H. , Benzerara O. , Semenov A. N.
Published: April 2022

The spatiotemporal correlations of the local stress tensor in supercooled liquids are studied both theoretically and by molecular dynamics simulations of a two-dimensional (2D) polydisperse Lennard-Jones system. Asymptotically exact theoretical equations defining the dynamical structure factor and all components of the stress correlation tensor for low wave-vector q are presented in terms of the generalized (q-dependent) shear and longitudinal relaxation moduli, G(q, t) and K(q, t). We developed a rigorous approach (valid for low q) to calculate K(q, t) in terms of certain bulk correlation functions (for q = 0), the static structure factor S(q), and thermal conductivity κ. The proposed approach takes into account both the thermostatting effect and the effect of polydispersity. The theoretical results for the (q, t)-dependent stress correlation functions are compared with our simulation data, and an excellent agreement is found for qb̄≲0.5 (with b̄ being the mean particle diameter) both above and below the glass transition without any fitting parameters. Our data are consistent with recently predicted (both theoretically and by simulations) long-range correlations of the shear stress quenched in heterogeneous glassy structures.
Multidimensional minimum-work control of a 2D Ising model
Authors: Louwerse Miranda D. , Sivak David A.
Published: April 2022

A system’s configurational state can be manipulated using dynamic variation of control parameters, such as temperature, pressure, or magnetic field; for finite-duration driving, excess work is required above the equilibrium free-energy change. Minimum-work protocols in multidimensional control-parameter space have the potential to significantly reduce work relative to one-dimensional control. By numerically minimizing a linear-response approximation to the excess work, we design protocols in control-parameter spaces of a 2D Ising model that efficiently drive the system from the all-down to all-up configuration. We find that such designed multidimensional protocols take advantage of more flexible control to avoid control-parameter regions of high system resistance, heterogeneously input and extract work to make use of system relaxation, and flatten the energy landscape, making accessible many configurations that would otherwise have prohibitively high energy and, thus, decreasing spin correlations. Relative to one-dimensional protocols, this speeds up the rate-limiting spin-inversion reaction, thereby keeping the system significantly closer to equilibrium for a wide range of protocol durations and significantly reducing resistance and, hence, work.
Particle–hole asymmetry and quantum confinement effects on the magneto-optical response of topological insulator thin-films
Authors: Asmar Mahmoud M. , Gupta Gaurav , Tse Wang-Kong
Published: April 2022

Intrinsically broken symmetries in the bulk of topological insulators (TIs) are manifested in their surface states. Despite particle–hole asymmetry in TIs, it has often been assumed that their surface states are characterized by a particle–hole symmetric Dirac energy dispersion. In this work, we demonstrate that the effect of particle–hole asymmetry is essential to correctly describe the energy spectrum and the magneto-optical response in TIs thin-films. In thin-films of TIs with a substantial degree of particle–hole symmetry breaking, such as Sb2Te3, the longitudinal optical conductivity displays absorption peaks arising from optical transitions between bulk and surface Landau levels for low photon energies. The transition energies between the bulk and surface Landau levels exhibit clearly discernable signatures from those between surface Landau levels due to their distinct magnetic field dependence. Bulk contributions to the magneto-optical conductivity in a TI thin-film are enhanced via one type of doping while being suppressed by the other. This asymmetric dependence on the type of doping aids in revealing the particle–hole asymmetry in TI thin-films.
Convection-induced bridging during alloy solidification
Authors: Kumar Virkeshwar , Sakalkale Ketan , Karagadde Shyamprasad
Published: April 2022

In this work, the effect of solute expansion coefficient on the natural convection and freezing front propagation is investigated by performing three-side cooled solidification experiments. Four different aqueous salt solutions, and different compositions thereof, were employed for experimentation. The mixtures were solidified to analyze the effect of solute expansion coefficients on the convection currents and the composition distribution in the bulk. The initial compositions were chosen such that all cases have the same primary solid fraction at eutectic temperature, for obtaining similar compositional changes in the bulk liquid at various stages. Similar cooling conditions were also maintained to ensure that the variation in convection strength is primarily caused by different solute expansion coefficients. A distinct observation of the free surface freezing before the bulk, termed bridging, is reported in certain cases. Further analysis revealed that the bridging could be attributed to a difference in solute convection caused by the solute expansion coefficient. Numerical simulations were performed to further ascertain the plausible initiation mechanisms for bridging. The predicted compositional and solid fraction distribution revealed lesser solute accumulation near the surface, for the lower solute expansion cases, and the resulting increase in the tendency of freezing at the top. An upper limit for the ratio of solutal to thermal Rayleigh numbers in the experimental conditions has been identified for the occurrence of bridging in high Prandtl number fluids.
Hierarchical equations of motion approach to hybrid fermionic and bosonic environments: Matrix product state formulation in twin space
Authors: Ke Yaling , Borrelli Raffaele , Thoss Michael
Published: April 2022

We extend the twin-space formulation of the hierarchical equations of motion approach in combination with the matrix product state representation [R. Borrelli, J. Chem. Phys. 150, 234102 (2019)] to nonequilibrium scenarios where the open quantum system is coupled to a hybrid fermionic and bosonic environment. The key ideas used in the extension are a reformulation of the hierarchical equations of motion for the auxiliary density matrices into a time-dependent Schrödinger-like equation for an augmented multi-dimensional wave function as well as a tensor decomposition into a product of low-rank matrices. The new approach facilitates accurate simulations of non-equilibrium quantum dynamics in larger and more complex open quantum systems. The performance of the method is demonstrated for a model of a molecular junction exhibiting current-induced mode-selective vibrational excitation.
Intelligent regulation of VO2-PDMS-driven radiative cooling
Authors: Liu Yang , Tian Yanpei , Liu Xiaojie , Chen Fangqi , Caratenuto Andrew , Zheng Yi
Published: April 2022

Passive radiative cooling, radiating energy from objects to the outer space through the Earth's atmospheric window, offers promising solutions for passive building cooling and renewable energy harvesting. However, static passive radiative cooling systems with a fixed thermal emissivity cannot automatically regulate emission in response to varying ambient temperature. Here, we propose an intelligent cooling system composed of nanoporous polyethylene, which acts as a solar reflector and a nanograting radiative cooler using the phase-transition material vanadium dioxide (VO2) and polydimethylsiloxane (PDMS). The top reflector enables the cooling system to reflect solar irradiation during the daytime, and the bottom cooler plays the role of switching radiative cooling in the spectrum band (8 μm < λ < 13 μm) due to the phase transition characteristic of VO2, contributing to the temperature of radiative cooler near a critical temperature. Meanwhile, continuous stretching of the material can achieve dynamic radiative cooling via deformation of the elastic PDMS substrate to realize different desired cooling temperatures. The proposed VO2-PDMS-driven radiative cooling system can not only intelligently switch between “on” and “off” radiative cooling modes but also adjust thermal comfort in its on mode in response to changes in the ambient temperature. This work has a great potential to be applied in the intelligent temperature regulation of buildings, vehicles, and utilities.
Origin of the discrepancy between the fundamental and optical gaps and native defects in two dimensional ultra-wide bandgap semiconductor: Gallium thiophosphate
Authors: Shen Tao , Zhang Chen , Qiu Chen , Deng Hui-Xiong
Published: April 2022

Ultra-wide bandgap (UWBG) semiconductors have great potential for high-power electronics, radio frequency electronics, deep ultraviolet optoelectronic devices, and quantum information technology. Recently, the two-dimensional UWBG GaPS4 was first applied to the solar-blind photodetector in experiments, which was found to have remarkable performance, such as high responsivity, high quantum efficiency, etc., and promising applications in optoelectronic devices. However, the knowledge of monolayer (ML) GaPS4 for us is quite limited, which hinders its design and application in optoelectronic devices. Here, we focus on the properties of electronic structure and intrinsic defects in ML GaPS4 by first-principles calculations. We confirmed that the fundamental gap of ML GaPS4 is 3.87 eV, while the optical gap is 4.22 eV. This discrepancy can be attributed to the inversion symmetry of its structure, which limits the dipole transitions from valence band edges to conduction band edges. Furthermore, we found that intrinsic defects are neither efficient p-type nor n-type dopants in ML GaPS4, which is consistent with experimental observations. Our results also show that if one expects to achieve p-type ML GaPS4 by selecting the appropriate dopant, P-rich conditions should be avoided for the growth process, while for achieving n-type doping, S-rich growth conditions are inappropriate. This is because due to the low strain energy, PS(c)+ has very low formation energy, which leads to the Fermi levels (EF) pinning at 0.35 eV above the valence band maximum and is not beneficial to achieve p-type ML GaPS4 under the P-rich conditions; the large lattice relaxation largely lowers the formation energy of SGa−, which causes the EF pinning at 0.72 eV below the conduction band minimum and severely prevents ML GaPS4 from being n-type doping under the S-rich conditions. Our studies of these fundamental physical properties will be useful for future applications of ML GaPS4 in optoelectronic devices.
Time-domain self-broadened and air-broadened nitrogen S-branch Raman linewidths at 80–200 K recorded in an underexpanded jet
Authors: Retter Jonathan E. , Koll Matthew , Richardson Daniel R. , Kearney Sean P.
Published: April 2022

We report pure-rotational N2–N2, N2–air, and O2–air S-branch linewidths for temperatures of 80–200 K by measuring the time-dependent decay of rotational Raman coherences in an isentropic free-jet expansion from a sonic nozzle. We recorded pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) spectra along the axial centerline of the underexpanded jet, within the barrel shock region upstream of the Mach disk. The dephasing of the pure-rotational Raman coherence was monitored using probe-time-delay scans at different axial positions in the jet, corresponding to varying local temperatures and pressures. The local temperature was obtained by fitting CARS spectra acquired at zero probe time delay, where the impact of collisions was minimal. The measured decay of each available Raman transition was fit to a dephasing constant and corrected for the local pressure, which was obtained from the CARS-measured static temperature and thermodynamic relationships for isentropic expansion from the known stagnation state. Nitrogen self-broadened transitions decayed more rapidly than those broadened in air for all temperatures, corresponding to higher Raman linewidths. In general, the measured S-branch linewidths deviated significantly in absolute and relative magnitudes from those predicted by extrapolating the modified exponential gap model to low temperatures. The temperature dependence of the Raman linewidth for each measured rotational state of nitrogen (J ≤ 10) and oxygen (N ≤ 11) was fit to a temperature-dependent power law over the measurable temperature domain (80–200 K) and extrapolated to both higher rotational states and room temperature. The measured and modeled low-temperature linewidth data provided here will aid low temperature gas-phase pressure measurements with fs/ps CARS.
Frequency comb in 1:3 internal resonance of coupled micromechanical resonators
Authors: Wang Xuefeng , Yang Qiqi , Huan Ronghua , Shi Zhan , Zhu Weiqiu , Jiang Zhuangde , Deng Zichen , Wei Xueyong
Published: April 2022

Frequency comb in microelectromechanical systems has attracted many concerns, which is expected to realize great achievements analogous with the optical frequency comb. Previous frequency combs are generated by mode coupling in a single micro-resonator. To pursuit more excellent tunability and robustness, it is impending to create a frequency comb through another way, i.e., coupled but relatively independent micro-resonators. In this work, a frequency comb in 1:3 internal resonance region of an electrostatically coupled microsystem is reported. We demonstrate the occurrence conditions and its influencing factors of the frequency comb. A dynamical explanation, which has good agreement with the experimental results, is presented to further reveal its intrinsic mechanism. Our finding provides a controllable method to produce a frequency comb that is beneficial to potential applications, such as signal processing and sensing sensitivity enhancement.
Generation of streamwise helical vortex loops via successive reconnections in early pipe transition
Authors: Ruan Shanxin , Xiong Shiying , You Jiaping , Yang Yue
Published: April 2022

We extend the vortex-surface field (VSF), a Lagrangian-based structure identification method, to investigate the vortex reconnection in temporally evolving transitional pipe flows. In the direct numerical simulation (DNS) of round pipe flows, a radial wave-like velocity disturbance is imposed on the inlet region to trigger the transition. The VSF isosurfaces are vortex surfaces composed of vortex lines, and they are concentric tubes with different wall distances at the initial time. The VSF evolution is calculated by the two-time method based on the DNS velocity field, and it is effective to identify the vortex reconnection. In the early stage of transition, the vortex surfaces are first corrugated with streamwise elongated bulges. The escalation and descent of vortex surfaces characterize the generation of high- and low-speed streaks and streamwise vortex pairs, along with the surge of the wall-friction coefficient. The resultant highly coiled and stretched vortex loops then reconnect with each other under the viscous cancelation mechanism. Subsequently, successive vortex reconnections occur via a “greedy snake” mechanism. The streamwise vortex loops consecutively capture the secondary vortex rings pinched off with self-reconnection, forming long helical vortex loops spanning over ten pipe radii in the streamwise direction. Finally, the Kelvin–Helmholtz instability of the shear layer at the trailing edge breaks down the streamwise helical vortex loops into turbulent spots.
Field and full-scale laboratory testing of prototype wildland fire shelters
Authors: Roise Joseph , Williams John , Barker Roger , Morton-Aslanis John
Published: April 2022

This paper describes a series of tests conducted to evaluate prototype fire shelters designed to provide enhanced thermal protective insulation in wildland fire burn-over events. Full-scale laboratory and field tests are used to compare the thermal performance of the prototypes with a fire shelter construction in current use in the United States. Laboratory tests showed that the prototype fire shelters outperformed the current shelter in providing fire-blocking thermal insulation in tests designed to simulate exposure to the intense flame conditions encountered in wildland fires. Field tests supported laboratory comparisons, but proved to be statistically inconclusive in differentiating shelter performance because of the variability inherent in thermal data obtained in field burns. This study confirmed the value of evaluating prototype shelter designs in laboratory tests capable of reproducibly simulating exposure to turbulent flames encountered in wildland fires.
Small-world connectivity dictates collective endothelial cell signaling
Authors: Lee Matthew D. , Buckley Charlotte , Zhang Xun , Louhivuori Lauri , Uhlén Per , Wilson Calum , McCarron John G.
Published: April 2022

Significance

The endothelium is the single layer of cells lining all blood vessels and acts as a central control hub to regulate multiple cardiovascular functions in response to hundreds of physiological stimuli. The detection of various physiological stimuli is distributed in spatially separated sites across the endothelium. Distributed sensing is difficult to reconcile with the requirement for coordinated cell activity across large regions of the endothelium. Here, we show that the endothelium resolves the issue by using a network with scale-free and small-world properties. The organization confers a high signal-propagation speed and a high degree of synchronizability across the endothelium. The network organization also explains the robust nature of endothelial communication and its resistance to damage or failure.
SIM key comparison in pneumatic gauge pressure for high accuracy pressure balances up to 120 kPa (SIM.M.P-K6)
Authors: Torres-Guzman J C , Aranzolo-Suarez J , Flores-Martinez F J , Cruz L de la , Olson D A , Forastieri J , Solano A , Neira C , Couto P R G , Palma J , Garcia S
Published: April 2022

Main text

This report describes the results of a pneumatic pressure standards key comparison among eleven SIM National Metrology Institutes to determine their degree of equivalence in the pressure range from 10 kPa to 120 kPa in gauge mode. The pilot laboratory was the Centro Nacional de Metrología (CENAM, Mexico). All participating institutes used pneumatic pressure balances as their pressure standard. The transfer standard was a complete system including a pressure balance with a free-deformation piston-cylinder assembly and a set of masses. Eleven participants completed their measurements and reported the pressure-dependent effective areas of the transfer standard at specified pressures with the associated uncertainties. NRC/Canada and BSJ/Jamaica withdrew the comparison by not sending their measurements. To link the results of the nine laboratories that sent their results to the CCM.P- NIST, the USA provided the reference values. To evaluate the compatibility of the results of the participants their relative deviations from those obtained by NIST results were analyzed. The results of six participating NMIs agree with the NIST reference values within their expanded uncertainties (k = 2) in the entire pressure range from 10 kPa to 120 kPa according to the normalized error equation method.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Determining damping terms in fractional wave equations
Authors: Kaltenbacher Barbara , Rundell William
Published: April 2022

This paper deals with the inverse problem of recovering an arbitrary number of fractional damping terms in a wave equation. We develop several approaches on uniqueness and reconstruction, some of them relying on Tauberian theorems that provide relations between the asymptotic behaviour of solutions in time and Laplace domains. The possibility of additionally recovering space-dependent coefficients or initial data is discussed. The resulting methods for reconstructing coefficients and fractional orders in these terms are tested numerically. In addition, we provide an analysis of the forward problem consisting of a multiterm fractional wave equation.
A novel MEMS inertial switch with frictional electrode
Authors: Du Liqun , Yang Xiaochen , Guo Bingjiang , Dong Yakun , Yuan Bowen , Zhao Jian , Liu Junshan
Published: April 2022

This paper presents a frictional MEMS inertial switch with aiming to solve the problems of short contact time and bounce. According to contact principle in MEMS inertial switch, a new enhanced contact method by friction is proposed and a frictional switch is designed. To compare the frictional switch with common rigid switch and flexible switch, three switches were fabricated by micro electroforming technology and tested by a standard dropping hammer system. The tested results show that the contact time of rigid switch, flexible switch and frictional switch is 13 μs, 85 μs and 620 μs, respectively. Both rigid switch and flexible switch have bounce problem, while frictional switch is closed stably without bounce phenomenon. Frictional MEMS inertial switch has great advantages in enhancing contact.
Decoupling method for four-degree-of-freedom automatic centering and tilting worktable
Authors: Shao Chunyu , Liu Yongmeng , Li Ruirui , Mei Yingjie , Tan Jiubin
Published: April 2022

The ultra-precise measurement of aero-engine rotor geometry error is the basis of its assembly, and adjusting the rotor coaxially with the measurement rotation axis is the key to ensure the measurement accuracy. As a typical adjustment device for rotor alignment, the traditional method of applying a four-degree-of-freedom centering and tilting table for adjustment does not take into account the coupling effect caused by the position of each adjustment motor not being perfectly perpendicular to each other, this paper gives the calibration method of the angle between each adjustment motor and the starting position of the angle grating, analyzes the principle of eccentricity and tilt adjustment and deduces the coupling solution method. Subsequently, the size of the coupling between the two adjustments is analyzed and an efficient adjustment method is given for its mechanical structure characteristics. The experimental results show that the platform can effectively decouple and quickly converge to the setting values of 0.3 µm and 0.5′′ for different initial eccentric distance and tilt angle. With the same adjustment accuracy, the number of adjustments is reduced by more than 50% and more than 37.5%, respectively, compared with the non-decoupled method.
Stability and bifurcation phenomena in asymptotically Hamiltonian systems
Authors: Sultanov Oskar A
Published: April 2022

The influence of time-dependent perturbations on an autonomous Hamiltonian system with an equilibrium of center type is considered. It is assumed that the perturbations decay at infinity in time and vanish at the equilibrium. In this case the stability and the long-term behaviour of trajectories depend on nonlinear and non-autonomous terms of equations. The paper investigates bifurcations associated with a change of Lyapunov stability of the equilibrium and the emergence of new attracting or repelling states in the perturbed non-autonomous system. The dependence of bifurcations on the structure of perturbations is discussed.
Improving small animal cone beam CT resolution by mitigating x-ray focal spot induced blurring via deconvolution
Authors: Hu Xiaoyu , Zhong Yuncheng , Huang Yanqi , Shen Chenyang , Jia Xun
Published: April 2022

Objective. Modern preclinical small animal radiation platforms utilize cone beam computerized tomography (CBCT) for image guidance and experiment planning purposes. The resolution of CBCT images is of particular importance for visualizing fine animal anatomical structures. One major cause of spatial resolution reduction is the finite size of the x-ray focal spot. In this work, we proposed a simple method to measure x-ray focal spot intensity map and a CBCT image domain deblurring model to mitigate the effect of focal spot-induced image blurring. Approach. We measured a projection image of a tungsten ball bearing using the flat panel detector of the CBCT platform. We built a forward blurring model of the projection image and derived the spot intensity map by deconvolving the measured projection image. Based on the measured spot intensity map, we derived a CBCT image domain blurring model for images reconstructed by the filtered backprojection algorithm. Based on this model, we computed image domain blurring kernel and improved the CBCT image resolution by deconvolving the CBCT image. Main results. We successfully measured the x-ray focal spot intensity map. The spot size characterized by full width at half maximum was ∼0.75 × 0.55 mm2 at 40 kVp. We computed image domain convolution kernels caused by the x-ray focal spot. A simulation study on noiseless projections was performed to evaluate the spatial resolution improvement exclusively by the focal spot kernel, and the modulation transfer function (MTF) at 50% was increased from 1.40 to 1.65 mm−1 for in-plane images and 1.05–1.32 mm−1 for cross-plane images. Experimental studies on a CT insert phantom and a plastinated mouse phantom demonstrated improved spatial resolution after image domain deconvolution, as indicated by visually improved resolution of fine structures. MTF at 50% was improved from 1.00 to 1.12 mm−1 for in-plane direction and from 0.72 to 0.84 mm−1 for cross-plane direction. Significance. The proposed method to mitigate blurring caused by finite x-ray spot size and improve CBCT image resolution is simple and effective.
Real-time liver tumor localization via a single x-ray projection using deep graph neural network-assisted biomechanical modeling
Authors: Shao Hua-Chieh , Wang Jing , Bai Ti , Chun Jaehee , Park Justin C , Jiang Steve , Zhang You
Published: April 2022

Objective. Real-time imaging is highly desirable in image-guided radiotherapy, as it provides instantaneous knowledge of patients’ anatomy and motion during treatments and enables online treatment adaptation to achieve the highest tumor targeting accuracy. Due to extremely limited acquisition time, only one or few x-ray projections can be acquired for real-time imaging, which poses a substantial challenge to localize the tumor from the scarce projections. For liver radiotherapy, such a challenge is further exacerbated by the diminished contrast between the tumor and the surrounding normal liver tissues. Here, we propose a framework combining graph neural network-based deep learning and biomechanical modeling to track liver tumor in real-time from a single onboard x-ray projection. Approach. Liver tumor tracking is achieved in two steps. First, a deep learning network is developed to predict the liver surface deformation using image features learned from the x-ray projection. Second, the intra-liver deformation is estimated through biomechanical modeling, using the liver surface deformation as the boundary condition to solve tumor motion by finite element analysis. The accuracy of the proposed framework was evaluated using a dataset of 10 patients with liver cancer. Main results. The results show accurate liver surface registration from the graph neural network-based deep learning model, which translates into accurate, fiducial-less liver tumor localization after biomechanical modeling (<1.2 (±1.2) mm average localization error). Significance. The method demonstrates its potentiality towards intra-treatment and real-time 3D liver tumor monitoring and localization. It could be applied to facilitate 4D dose accumulation, multi-leaf collimator tracking and real-time plan adaptation. The method can be adapted to other anatomical sites as well.
Partially observable Szilárd engines
Authors: Still Susanne , Daimer Dorian
Published: April 2022

Almost a century ago, Leo Szilárd replaced Maxwell’s ‘demon’ by machinery. The resulting information engine concept laid the foundation for studying the physical nature of information. Szilárd reduced the demon’s role to mapping an observable onto a work extraction protocol, thereby creating and utilizing a meta-stable memory. While Szilárd demonstrated that this map can be implemented mechanistically, it was not chosen automatically by the demon, or ‘observer’, but rather given a priori. This choice implements the demon’s intelligence. In Szilárd’s original setup, the choice is trivial, but we show here that nontrivial data representations emerge for generalized, partially observable Szilárd engines. Partial observability is pervasive in real world systems with limited sensor types and information acquisition bandwidths. Generalized information engines may run work extraction at a higher temperature than memory formation, which enables the combined treatment of heat- and information engines. To date, Szilárd’s (fully observable) information engine still serves as a canonical example. Implications of partial observability are under-explored, despite their ubiquitous nature. We provide here the first physical characterization of observer memories that result in minimal engine dissipation. We introduce a new canonical model, simple yet physically rich: a minor change to Szilárd’s engine—inserting the divider at an angle—results in partially observable engines. We demonstrate how the demon’s intelligence can be automated. For each angle and for each temperature ratio, an optimal memory is found algorithmically, enabling the engine to run with minimal dissipation. While naive coarse graining is sufficient for the special case of full observability, in general, minimally dissipative observers use probabilistic memories. We propose a simple model for an implementation of these memories, and construct a nontrivial physical codebook. We characterize the performance of engines with minimally dissipative memories, and compare their quality to that of engines using an optimized coarse graining of the observable.
Neural network acceleration of large-scale structure theory calculations
Authors: DeRose Joseph , Chen Shi-Fan , White Martin , Kokron Nickolas
Published: April 2022

We make use of neural networks to accelerate the calculation of power spectra required for the analysis of galaxy clustering and weak gravitational lensing data. For modern perturbation theory codes, evaluation time for a single cosmology and redshift can take on the order of two seconds. In combination with the comparable time required to compute linear predictions using a Boltzmann solver, these calculations are the bottleneck for many contemporary large-scale structure analyses. In this work, we construct neural network-based surrogate models for Lagrangian perturbation theory (LPT) predictions of matter power spectra, real and redshift space galaxy power spectra, and galaxy-matter cross power spectra that attain ∼ 0.1% (at one sigma) accuracy over a broad range of scales in a ωCDM parameter space. The neural network surrogates can be evaluated in approximately one millisecond, a factor of 1000 times faster than the full Boltzmann code and LPT computations. In a simulated full-shape redshift space galaxy power spectrum analysis, we demonstrate that the posteriors obtained using our surrogates are accurate compared to those obtained using the full LPT model. We make our surrogate models public at https://github.com/sfschen/EmulateLSS, so that others may take advantage of the speed gains they provide to enable rapid iteration on analysis settings, something that is essential in complex contemporary large-scale structure analyses.
Analysis of the discharge plasma impedance of copper vapor laser
Authors: Singh Dheeraj K , Dikshit B , Vijayan R , Mukherjee Jaya , Rawat V S
Published: April 2022

In the pursuit to analyze the impedance of copper vapor lasers (CVLs) in different conditions, a novel approach has been proposed in this paper. The underdamped behavior of the voltage waveform across the CVL is leveraged to compute the impedance of high-voltage discharge plasma in the laser. This methodology provides an accurate idea of the discharge plasma resistance and inductance as it is calculated on the basis of experimental voltage waveforms obtained from the laser system. The laser head inductance remains almost fixed and equivalent to ∼0.47 µH whereas the laser resistance changes between 34 Ω and 11 Ω depending on the discharge condition and its constituents. A critical evaluation of CVL impedance is done in all experimentally possible conditions, and a methodology has been proposed to maintain the CVL impedance, which results in the power stability of the laser in oscillator–amplifier configuration. The laser impedance variation w.r.t. time, pressure, operating voltage and electrode pin configuration has been investigated. The impact of the localized electric field at the electrode on the laser resistance has also been emphasized in this paper. A good concurrence exists between the calculated laser impedance and its experimental behavior.
Gyrokinetic simulation of low-n Alfvénic modes in tokamak HL-2A plasmas
Authors: Lin Wen-Hao , Li Ji-Quan , Garcia J , Mazzi S
Published: April 2022

The turbulence characteristics of plasmas with internal transport barriers in the HL-2A tokamak are analyzed by means of linear gyrokinetic simulations. It is found that turbulence is dominated by the ion temperature gradient (ITG) mode together with large-scale modes characterized by high-frequency electromagnetic fluctuation, which are destabilized by the steep ion temperature gradient in the weak magnetic shear regime. Comparison with solutions of analytical dispersion relations shows that their linear features match well with the beta-induced Alfvén eigenmode branch of the shear Alfvénic spectrum. It is further clarified that the large population of fast ions in these plasmas plays a stabilization role through the dilution mechanism in high-n ITG mode regimes.
Design and high-power test of 800-kW UHF klystron for CEPC
Authors: Xiao Ou-Zheng , Fukuda Shigeki , Zhou Zu-Sheng , Zaib Un-Nisa , Wang Sheng-Chang , Lu Zhi-Jun , Pei Guo-Xi , Iqbal Munawar , Dong Dong
Published: April 2022

To reduce the energy demand and operation cost for circular electron positron collider (CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-kW continuous wave (CW) klystron operating at frequency of 650-MHz has been designed. The results of beam–wave interaction simulation with several different codes are presented. The efficiency is optimized to be 65% with a second harmonic cavity in three-dimensional (3D) particle-in-cell code CST. The effect of cavity frequency error and mismatch load on efficiency of klystron have been investigated. The design and cold test of reentrant cavities are described, which meet the requirements of RF section design. So far, the manufacturing and high-power test of the first klystron prototype have been completed. When the gun operated at DC voltage of 80 kV and current of 15.4 A, the klystron peak power reached 804 kW with output efficiency of about 65.3% at 40% duty cycle. The 1-dB bandwidth is ±0.8 MHZ. Due to the crack of ceramic window, the CW power achieved about 700 kW. The high-power test results are in good agreement with 3D simulation.
High Chern number phase in topological insulator multilayer structures: A Dirac cone model study
Authors: Wang Yi-Xiang , Li Fu-Xiang
Published: April 2022

We employ the Dirac cone model to explore the high Chern number (C) phases that are realized in the magnetic-doped topological insulator (TI) multilayer structures by Zhao et al. [Nature
588 419 (2020)]. The Chern number is calculated by capturing the evolution of the phase boundaries with the parameters, then the Chern number phase diagrams of the TI multilayer structures are obtained. The high-C behavior is attributed to the band inversion of the renormalized Dirac cones, along with which the spin polarization at the Γ point will get increased. Moreover, another two TI multilayer structures as well as the TI superlattice structures are studied.
Geophysical surveys in archaeological sites in Baucina (Palermo)
Authors: Leucci G. , Cubito A. , De Giorgi L. , Pappalardo S. , Giaccone T. , Greco C. , Carrozzo A. R. , Longhitano L. , Comisi F.
Published: April 2022

The archaeological site of Monte Carrozza and Monte Falcone dominates in the south and east of the modern town of Baucina. These are two reliefs of modest size, separated by a small hill elongated in an East-West direction where the cliffs stand the necropolis. On these hills, probably in the sixth century. B.C., settled people, sicane that at the end of the century came into contact with the Greek colonies of Himera and the Punic Soluntum, as the research conducted in the last decade have demonstrated. Located in the hinterland, on the watershed between the river San Leonardo and Milicia, the sites are located in a critical point, in an area open to the connections between Palermo, Solunto and Himera. Archaeological excavations are conducted by the Chair of Ancient Topography of the University of Palermo, in agreement and cooperation with the Superintendence of Cultural Heritage of Palermo and with the logistical and financial support of the City of Baucina. Investigations affecting a sector of the cemetery located along the southern slope of Monte Falcone to combat the phenomenon of illegal excavations. For this purpose were undertaken, a series of geophysical surveys were. The survey results showed the presence of various structures, likely archaeological interest. Subsequent excavations made in areas investigated by geophysics have unearthed different funerary structures: burials in graves or nasturtium, cremation within pithoi or amphorae. The dead were accompanied by grave goods of the Greek tradition: skyphoi, achromatic cups, etc. Particular interest is a large tomb in an artificial cave entrance that consists of pillars and lintel plaster. The grave diggers violated by poachers is unique for their monumental architecture. It was reached by a corridor carved in the rock, in whose landfilling and numerous ceramic fragments were recovered a bronze coin.