Direct Integration Research Articles

Multisampling with Sigma-Delta ADCs for Medium-Voltage Cascaded H-Bridge Converters

The control of medium-voltage cascaded H-bridge (CHB) converters demands precise, high-bandwidth, low-latency, and isolated measurements. Traditional analog-to-digital converters (ADCs) can facilitate multisampling methods to meet these requirements but do not provide the high-voltage galvanic isolation that may be necessary in a system operating at medium voltage. Sigma-Delta ADCs (SD-ADCs) present a promising alternative due to their superior noise rejection capabilities and direct integration with the optical fiber interface. However, the inherent latency associated with SD-ADCs, stemming from their operating principles, poses challenges when integrating them with multisampling methods. This paper analyzes the integration of multisampling techniques with SD-ADCs for medium-voltage CHB converter control. First, the impact of SD-ADC-induced delays on the control system is elucidated from the passivity perspective. Second, the practical implementation of multisampling with SD-ADCs is discussed in detail. Finally, experimental results from a 2400 Vrms medium-voltage CHB converter are presented to validate the analysis and illustrate the effectiveness of the proposed implementation.

Asymmetry in the tidal tails of open star clusters from direct N-body integrations in Milgrom-law dynamics

Numerical simulations of star clusters in quasilinear modified Newtonian dynamics (QUMOND) orbiting in a Galactic disk potential show that the leading tidal arm of open star clusters typically contain more members than the trailing arm. However, these type of simulations are performed by solving the field equations of QUMOND and have already proven impractical for star cluster masses of around 5000\,$M_ Nearby star clusters exhibit (maximum) masses of 1000\,$M_ (or approx 1000 particles) and cannot be simulated reliably in field-theoretical formulations of modified Newtonian dynamics (MOND) at present. Differences in the formation and evolution of tidal tails of open star clusters in the Newtonian and in the MONDian context are explored in the case of an equal-mass $n=400$ particle cluster ($M_ tot =200\,M_ sun$). To handle particle numbers below the QUMOND-limit, we simulated the star cluster in Milgrom-law dynamics (MLD). Milgrom's law $g_ N M |/a_0)a_ M $ has been postulated to be valid for discrete systems in vectorial form, while MLD resembles QUMOND in that the acceleration of a particle outside any isolated mass concentration scales inversely with the distance. However, in MLD, an internally Newtonian binary will follow a Newtonian rather than a MONDian path around the Galactic centre. To suppress the Newtonisation of compact subsystems in the star cluster, the gravitational force is softened below particle distances of 0.001\,pc approx 206\,AU. Thus, MLD can only be considered as an approximation of a full MOND-theoretical description of discrete systems that are internally in the MOND regime. The MLD equations of motion are integrated by the standard Hermite scheme that is generally applied to Newtonian $N$-body systems. In this work, we have extended this scheme to solve for the accelerations and jerks associated with Milgrom's law. We found that the tidal tails of a low-mass star cluster are populated asymmetrically in the MLD treatment, similarly to what is seen in QUMOND simulations of higher mass star clusters. In the MLD simulations, the leading tail hosts up to twice as many members than the trailing arm, while the low-mass open star cluster dissolves approximately 25<!PCT!> faster than in the respective Newtonian case. Furthermore, the numerical simulations show that the Newtonian integrals of motion are not conserved in MLD. However, the case of an isolated binary in the deep MOND limit can be handled analytically. The velocity of the Newtonian centre of mass does not increase continuously, but instead it wobbles around the constantly moving MLD centre of mass.

Spinning waveforms in cubic effective field theories of gravity

We derive analytic all-order-in-spin expressions for the leading-order time-domain waveforms generated in the scattering of two Kerr black holes with arbitrary masses and spin vectors in the presence of all independent cubic deformations of Einstein-Hilbert gravity. These are the two parity-even interactions I1 and G3, and the parity-odd ones Ĩ1 and G~3. Our results are obtained using three independent methods: a particularly efficient direct integration and tensor reduction approach; integration by parts combined with the method of differential equations; and finally a residue computation. For the case of the G3 and G~3 deformations we can express the spinning waveform in terms of the scalar waveform with appropriately shifted impact parameters, which are reminiscent of Newman-Janis shifts. For I1 and Ĩ1 similar shifts occur, but are accompanied by additional contributions that cannot be captured by simply shifting the scalar I1 and Ĩ1 waveforms. We also show the absence of leading-order corrections to gravitational memory. Our analytic results are notably compact, and we compare the effectiveness of the three methods used to obtain them. We also briefly comment on the magnitude of the corrections to observables due to cubic deformations.

Orbital dynamics of the solar basin

We study the dynamics of the solar basin — the accumulated population of weakly-interacting particles on bound orbits in the Solar System. We focus on particles starting off on Sun-crossing orbits, corresponding to initial conditions of production inside the Sun, and investigate their evolution over the age of the Solar System. A combination of analytic methods, secular perturbation theory, and direct numerical integration of orbits sheds light on the long- and short-term evolution of a population of test particles orbiting the Sun and perturbed by the planets. Our main results are that the effective lifetime of a solar basin at Earth’s location is τeff = 1.20 ± 0.09 Gyr, and that there is annual (semi-annual) modulation of the basin density with known phase and amplitude at the fractional level of 6.5% (2.2%). These results have important implications for direct detection searches of solar basin particles, and the strong temporal modulation signature yields a robust discovery channel. Our simulations can also be interpreted in the context of gravitational capture of dark matter in the Solar System, with consequences for any dark-matter phenomenon that may occur below the local escape velocity.

Spin-orbit entangled moments and magnetic exchange interactions in cobalt-based honeycomb magnets BaCo2(XO4)2 (X = P, As, Sb)

Co-based honeycomb magnets have been actively studied recently for the potential realization of emergent quantum magnetism therein such as the Kitaev spin liquid. Here we employ density functional and dynamical mean-field theory methods to examine a family of the Kitaev magnet candidates BaCo2(XO4)2 (X = P, As, Sb), where the compound with X = Sb being not synthesized yet. Our study confirms the formation of Mott insulating phase and the Jeff = 1/2 spin moments at Co2+ sites despite the presence of a sizable amount of trigonal crystal field in all three compounds. The pnictogen substitution from phosphorus to antimony significantly changes the in-plane lattice parameters and direct overlap integral between the neighboring Co ions, leading to the suppression of the Heisenberg interaction. More interestingly, the marginal antiferromagnetic nearest-neighbor Kitaev term changes sign into a ferromagnetic one and becomes sizable at the X = Sb limit. Our study suggests that the pnictogen substitution can be a viable route to continuously tune magnetic exchange interactions and to promote magnetic frustration for the realization of potential spin liquid phases in BaCo2(XO4)2.

Darcy–Forchheimer gravity currents in porous media

We theoretically and experimentally study gravity currents of a Newtonian fluid advancing in a two-dimensional, infinite and saturated porous domain over a horizontal impermeable bed. The driving force is due to the density difference between the denser flowing fluid and the lighter, immobile ambient fluid. The current is taken to be in the Darcy–Forchheimer regime, where a term quadratic in the seepage velocity accounts for inertial contributions to the resistance. The volume of fluid of the current varies as a function of time as $\sim T^{\gamma }$ , where the exponent parameterizes the case of constant volume subject to dam break ( $\gamma =0$ ), of constant ( $\gamma =1$ ), waning ( $\gamma <1$ ) and waxing inflow rate ( $\gamma >1$ ). The nonlinear governing equations, developed within the lubrication theory, admit self-similar solutions for some combinations of the parameters involved and for two limiting conditions of low and high local Forchheimer number, a dimensionless quantity involving the local slope of the current profile. Another parameter $N$ expresses the relative importance of the nonlinear term in Darcy–Forchheimer's law; values of $N$ in practical applications may vary in a large interval around unity, e.g. $N\in [10^{-5},10^{2}]$ ; in our experiments, $N\in [2.8,64]$ . Sixteen experiments with three different grain sizes of the porous medium and different inflow rates corroborate the theory: the experimental nose speed and current profiles are in good agreement with the theory. Moreover, the asymptotic behaviour of the self-similar solutions is in excellent agreement with the numerical results of the direct integration of the full problem, confirming the validity of a relatively simple one-dimensional model.

Enhanced subsurface edge detection using a 3D integration operator

Orientation analysis is widely employed in edge and line detection and is an important step in object detection and illumination. The direct application of a 3D integration orientation operator to a seismic image is proposed to enhance efficiency and improve delineation of subsurface edges. The primary objective in doing so is to overcome the weaknesses associated with gradient operator-based edge detections, namely, noise sensitivity due to using a fixed smoothing window and orientation bias of the gradient operators. Our study shows that the application of a 3D integration operator to a seismic data volume results in more coherent edges than the gradient-based Sobel operator. In addition, the computation efficiency improves significantly in comparison to a direct 2D integration operator.

Seismic Resistance of Reinforced Concrete Building Frames Based on Interval Assessment of the Coefficient of Permissible Damage

The main method for assessing the seismic resistance of buildings in the standards of most countries is the linear-spectral method. This method allows for the calculation of the spatial model of a building for seismic load in the elastic range without resorting to direct integration of the equations of motion. Nonlinear characteristics of reinforced concrete structure materials are usually considered integrally using the reduction factor. However, the values of this factor in the Russian standards are not sufficiently substantiated, as the later studies show. To determine the coefficient of permissible damage (reduction factor), six reinforced concrete frames were considered, with different parameters such as span length, number of spans, and number of floors. The design parameters of beams and columns (section sizes, reinforcement, etc.) were preliminarily selected based on the calculation using the linear-spectral method. In the second stage, numerical modeling was carried out in the OpenSEES PC to implement the pushover analysis procedure. Then, the coefficient of permissible damage was estimated by processing the capacity curves obtained on the basis of nonlinear static calculation. The value of the sought coefficients is practically not affected by the number of stores of the frame; however, with an increase in the number of spans, the coefficient K1 increases, which is explained by a decrease in the plasticity of the system. On average, for the frames under consideration, the coefficient K1 was 0.526, which is 1.5 times greater than the coefficient proposed in modern Russian standards, K1 = 0.35. The results obtained on the basis of pushover analysis are compared with the coefficients K1 determined through the values of the average degree of damage (d) of the buildings according to the modified seismic scale MMSK-86. For various types of reinforced concrete frame buildings, K1 = 0.51 was obtained. It is recommended that the coefficient K1 for reinforced concrete frame buildings should be increased to a value of at least K1 = 0.5 in the Russian standard.

Fast and precise dose estimation for very high energy electron radiotherapy with graph neural networks

IntroductionExternal beam radiotherapy (RT) is one of the most common treatments against cancer, with photon-based RT and particle therapy being commonly employed modalities. Very high energy electrons (VHEE) have emerged as promising candidates for novel treatments, particularly in exploiting the FLASH effect, offering potential advantages over traditional modalities.MethodsThis paper introduces a Deep Learning model based on graph convolutional networks to determine dose distributions of therapeutic VHEE beams in patient tissues. The model emulates Monte Carlo (MC) simulated doses within a cylindrical volume around the beam, enabling high spatial resolution dose calculation along the beamline while managing memory constraints.ResultsTrained on diverse beam orientations and energies, the model exhibits strong generalization to unseen configurations, achieving high accuracy metrics, including a δ-index 3% passing rate of 99.8% and average relative error <1% in integrated dose profiles compared to MC simulations.DiscussionNotably, the model offers three to six orders of magnitude increased speed over full MC simulations and fast MC codes, generating dose distributions in milliseconds on a single GPU. This speed could enable direct integration into treatment planning optimization algorithms and leverage the model’s differentiability for exact gradient computation.

Perturbative QCD meets phase quenching: The pressure of cold quark matter

Nonperturbative inequalities constrain the thermodynamic pressure of quantum chromodynamics (QCD) with its phase-quenched version, a sign-problem-free theory amenable to lattice treatment. In the perturbative regime with a small QCD coupling constant αs, one of these inequalities manifests as an O(αs3) difference between the phase-quenched and QCD pressures at large baryon chemical potential. In this work, we generalize state-of-the-art algorithmic techniques used in collider physics to address large-scale multiloop computations at finite chemical potential, by direct numerical integration of Feynman diagrams in momentum space. Using this novel approach, we evaluate this O(αs3) difference and show that it is a gauge-independent and small positive number compared to the known perturbative coefficients at this order. This implies that at high baryon densities, phase-quenched lattice simulations can provide a complementary nonperturbative method for accurately determining the pressure of cold quark matter at O(αs3). Published by the American Physical Society 2024

A study of self-similar vector fields in bianchi type III spacetime via Rif tree approach

Abstract In this study, we use the Rif tree approach to explore self-similar vector fields in Bianchi type III spacetime. This work adopt a computer-based method to transform symmetry equations into an involutive form that is simplified and divides the integration problem into multiple cases, each represented as a tree structure. In some cases, the metric functions are subject to particular constraints. These conditions allow one to solve the system of equations governing self-similar symmetries and provide explicit formulations for the metrics and their corresponding self-similar vector fields. This approach is novel in that it covers not only the analysis of the direct integration strategy but also some metrics that are practically relevant. For a detailed investigation of the created models, stability and physical importance are also considered.

Stretchable and High-Performance Fibrous Sensors Based on Ionic Capacitive Sensing for Wearable Healthcare Monitoring.

Electronic textiles with remarkable breathability, lightweight, and comfort hold great potential in wearable technologies and smart human-machine interfaces. Ionic capacitive sensors, leveraging the advantages of the electric double layer, offer higher sensitivity compared to traditional capacitive sensors. Current research on wearable ion-capacitive sensors has focused mainly on two-dimensional (2D) or three-dimensional (3D) device architectures, which show substantial challenges for direct integration with textiles and compromise their wearing experience on conformability and permeability. One-dimensional (1D) stretchable fiber materials serve as vital components in constructing electronic textiles, allowing for rich structural design, patterning, and device integration through mature textile techniques. Here, a stretchable functional fiber with robust mechanical and electrical performances is fabricated based on semi-solid metal and ionic polymer, which provided a high stretchability and good electrical conductivity, enabling seamless integration with textiles. Consequently, high-performance stretchable fiber sensors are developed through different device architecture designs, including pressure sensors with high sensitivity (7.21kPa-1), fast response (60ms/30ms), and excellent stability, as well as strain sensors with high sensitivity (GF = 1.05), wide detection range (0-300% strain), and excellent sensing stability under dynamic deformations.

An Efficient Analysis of Amplitude and Phase Dynamics in Networked MEMS-Colpitts Oscillators

Abstract This paper explores the interactions of both phase and amplitude in a network of N MEMS-Colpitts oscillators that are resistively coupled. The numerical simulations of the extensive networks of oscillators, required for emerging applications such as clock synchronization and neuromorphic computing, become computationally prohibitive as the number of oscillators increases. This complicates the design and evaluation of such systems, as understanding the effects of changes in coupling and design parameters can require many simulations. This study employs the method of multiple scales (MS) in combination with the harmonic balance method to convert the coupled differential equations governing the system of oscillators into a set of nonlinear evolution equations for the amplitude and phase of the oscillators. The amplitude and phase evolve on a timescale that is slow, commensurate with the damping in the system, compared with the fast timescale of the oscillation frequencies. The approach used in this study to describe the amplitude and phase dynamics offers significant computational efficiency (gains of 10× to 50× are shown) compared to direct numerical integration while maintaining an accurate representation of the response. The results of the presented simulations demonstrate the effect of coupling strength on the dynamics of the network, accounting for both phase and amplitude dynamics.

Optimizing Agricultural and Construction Tool Usage through Android Devices A Comprehensive Survey

An all-encompassing rental and booking platform for agricultural tools and construction tools designed to revolutionize the workflow in the agricultural sector and construction sector respectively. It is a versatile tool of central application that will bridge the gap between demand of tools and its supply. This will help the owners to effectively run their farm-lands. Providers will keep inventory for the tools and implementation of tool allotment. When customers don’t find the tools that they need in the current inventory they may purchase those from hardware shops. In that situation, the customers can buy tools from the selected hardware shops connected with the site by direct integration with the site owner’s shop. Real-time online tool availability checks and vendor invoice generation are required in this process when clients want to buy. A flexible communication system that can be developed as an application to facilitate customer communication directly with suppliers, which will be considerably more convenient than the conventional approaches and will remove the above.

Diverse general solitary wave solutions and conserved currents of a generalized geophysical Korteweg–de Vries model with nonlinear power law in ocean science

This article presents an analytical investigation performed on a generalized geophysical Korteweg–de Vries model with nonlinear power law in ocean science. To start with, achieving diverse solitary wave solutions to the generalized power‐law model involves using wave transformation, which reduces the model to a nonlinear ordinary differential equation. A direct integration approach is adopted to construct solutions in the beginning. This brings the emergence of interesting solutions like non‐topological solitons, trigonometric functions, exponential functions, elliptic functions, and Weierstrass functions in general structures. Besides, in a bid to secure more general exact solutions to the model, one adopts the extended Jacobi elliptic function expansion technique (for some specific cases of ). Thus, various cnoidal, snoidal, and dnoidal wave solutions to the understudied model are attained. The copolar trio explicated in a tabular form reveals that these solutions can be relapsed to various hyperbolic and trigonometric functions under certain criteria. Additionally, diverse graphical exhibitions of the dynamical attributes of the gained results are presented in a bid to have a sound understanding of the physical phenomena of the underlying model. Later, one gives the conserved vectors of the aforementioned equation by employing the standard multiplier approach.

Engineering Epitaxial Interfaces for Topological Insulator — Superconductor Hybrid Devices with Al Electrodes

AbstractProximity‐induced superconductivity in hybrid devices of topological insulators and superconductors offers a promising platform for the pursuit of elusive topological superconductivity and its anticipated applications, such as fault‐tolerant quantum computing. To study and harness such hybrid devices, a key challenge is the realization of highly functional material interfaces with a suitable superconductor featuring 2‐periodic parity‐conserving transport to ensure a superconducting hard‐gap free of unpaired electrons, which is important for Majorana physics. A superconductor well‐known for this characteristic is Al, however, its direct integration into devices based on tetradymite topological insulators has so far been found to yield non‐transparent interfaces. By focusing on Bi2Te3‐Al heterostructures, this study identifies detrimental interdiffusion processes at the interface through atomically resolved structural and chemical analysis, and showcases their mitigation by leveraging different interlayers – namely Nb, Ti, Pd, and Pt – between Bi2Te3 and Al. Through structural transformation of the interlayer materials (X) into their respective tellurides (XTe2) atomically‐sharp epitaxial interfaces are engineered and further characterized in low‐temperature transport experiments on Al‐X‐Bi2Te3‐X‐Al Josephson junctions and in complementary density functional theory calculations. By demonstrating functional interfaces between Bi2Te3 and Al, this work provides key insights and paves the way for the next generation of sophisticated topological devices.

A Comparison of Medical Education Policies in Japan and Singapore with a Focus on Governance: Implications for Korea

Among Asian nations, Japan, Singapore, and South Korea exemplify countries with high standards of medical quality. This review explores the differences in medical education policies between Japan and Singapore, particularly concerning governance, and discusses the implications for South Korea’s medical education policies. Relevant documents were analyzed by referencing scholarly articles and data from governmental and expert organizations in each country. In Japan, advances in medical education policies include initiatives such as the regional quota system and the core curriculum model, which emphasize stakeholder engagement and transparency. However, challenges persist due to limited stakeholder participation, necessitating a transition toward a more equitable governance paradigm. Singapore’s model features robust public-private partnerships with minimal direct governmental intervention, emphasizing innovation and community integration, as seen in the Healthier SG project. These case studies demonstrate effective governance involving significant stakeholder collaboration and strategic financial investments. Conversely, South Korea’s medical education policies face challenges from a predominantly government-centric approach, with an absence of cohesive governance structures and inadequate involvement from essential professional stakeholders. This situation has led to policy inconsistencies and a deficit of strategic direction, exacerbated by insufficient financial support for educational infrastructure and program development. The experiences of Japan and Singapore indicate that it would be beneficial for South Korea to adopt integrated governance frameworks that prioritize transparency and collaboration. Furthermore, increasing financial investment in medical education could mitigate existing deficiencies and improve the quality and effectiveness of its healthcare education system.

Full‐Spectrum Light‐Harvesting Solar Thermal Electrocatalyst Boosts Oxygen Evolution

AbstractEnabling high‐efficiency solar thermal conversion (STC) at catalytic active site is critical but challenging for harnessing solar energy to boost catalytic reactions. Herein, we report the direct integration of full‐spectrum STC and high electrocatalytic oxygen evolution activity by fabricating a hierarchical nanocage architecture composed of graphene‐encapsulated CoNi nanoparticle. This catalyst exhibits a near‐complete 98 % absorptivity of solar spectrum and a high STC efficiency of 97 %, which is superior than previous solar thermal catalytic materials. It delivers a remarkable potential decrease of over 240 mV at various current densities for electrocatalytic oxygen evolution under solar illumination, which is practically unachievable via traditionally heating the system. The high‐efficiency STC is enabled by a synergy between the regulated electronic structure of graphene via CoNi‐carbon interaction and the multiple absorption of lights by the light‐trapping nanocage. Theoretical calculations suggest that high temperature‐induced vibrational free energy gain promotes the potential‐limiting *O to *OOH step, which decreases the overpotential for oxygen evolution.

A block-based numerical strategy for modeling the dynamic out-of-plane behavior of unreinforced brick masonry walls

AbstractIn this paper, a numerical procedure is proposed to simulate the dynamic out-of-plane response of unreinforced masonry (URM) walls. A state-of-the-art damaging block-based model, originally developed for quasi-static simulations, is extended for the first time in a dynamic regime. The blocks are represented using solid 3D finite elements governed by a plastic-damage constitutive law for both tension and compression. A cohesive-frictional contact-based formulation is used to account for interactions between the blocks. A simplified mechanical characterization is formulated to improve efficiency in wall-level analyses. Dynamic simulation is performed using a generalized HHT-$$\alpha$$ α direct integration implicit solver and by implementing Rayleigh damping in the bulk. Such consideration allows the use of both mass and stiffness proportional terms of the Rayleigh damping without compromising efficiency. The strategy is applied to simulate incremental dynamic experiments performed on full-scale walls, showing good agreement between numerical and experimental results. The calibrated numerical model is then optimized to reduce computational effort while maintaining accuracy. The optimized model is used to investigate the effect of relative support motion on the one-way bending out-of-plane seismic response of URM walls, demonstrating the potential of the modeling strategy to explore the effect of boundary conditions that occur in real buildings but are often overlooked in laboratory experiments. This investigation also explores the adequacy of simplifications in capturing the effect of relative support motion, which can be adopted for simple modeling strategies commonly used in standard engineering practice.

Analytical evaluation of the elastic stresses in a multilayer spherical pressure vessel

An explicit-form solution is constructed for a problem on elastic deformation of a multilayer spherical vessel due to uniform internal pressure. The vessel is assembled of perfectly connected elastic layers whose material properties may arbitrarily vary across their thickness. The solution is constructed through the use of the single solid approach along with the modified scheme of the direct integration method which allow for the consideration of the multilayer vessel as a composite sphere with piecewise-variable profiles of the material properties. As a result, the original problem is reduced to solving a governing integral equation of the second kind whose solution is constructed in the form of the explicit dependence on the internal pressure. The solution is verified by the comparison with exact solutions derived by making use the method of tailored solutions for specific benchmark problems. By comparing our with the one for a functionally-graded sphere, whose material properties are evaluated through the use of the micromodular homogenization technique, the specific features of the circumferential stress are analyzed.