Two-dimensional Configuration Research Articles

Optically tuned soliton dynamics in Bose-Einstein condensates within dark traps

Abstract This study investigates the formation and dynamics of solitons in Bose–Einstein condensates (BECs) within dark traps generated by two crossed Laguerre–Gaussian (LG) beams with varying azimuthal indices ℓ . As the index ℓ increases, the potential transitions from a harmonic trap when ℓ = 1 to a square-well potential for larger values of ℓ . This transition allows us to study a range of soliton dynamics under different confinement conditions while maintaining the same BEC volume. Through the derivation of the Gross-Pitaevskii equation (GPE) and under these specific conditions in both one-dimensional and two-dimensional configurations, we explore the dynamics of solitons across multiple scenarios. The study examines two primary methods for solitons generation: the temporal modulation of the scattering length and the implementation of an initial potential barrier that is subsequently removed. The results indicate that the trap shape plays a critical role in the generation and interaction dynamics of solitons. In harmonic traps, solitons exhibit a behavior different from those observed in anharmonic traps, where the dynamics is significantly influenced by the azimuthal index of the trap. The ability to control soliton dynamics in BECs holds significant promise for applications in quantum technologies, precision sensing, and the exploration of fundamental quantum phenomena.

A Universal Target Plate Design Scheme for Stellarators: theoretical basis and its application to heat load control

Abstract This study introduces a novel divertor target design scheme for stellarators, grounded in mathematical treatments and tailored to control toroidal heat load distributions. Initially, a differential equation characterizing toroidally uniform heat load distribution has been established in a two-dimensional (2D) slab configuration, and its analytic solution has been obtained. Subsequently, a numerical scheme has been developed to adapt the analytic solution into the 3D surface shape of stellarator target. The effectiveness of this design scheme has been validated through simulations of the Chinese First Quasi-axisymmetric Stellarator (CFQS) using a suite of codes including HINT, FLARE and EMC3-EIRENE, where a toroidally uniform heat load distribution has been achieved with an island configuration. Further, the effects of input parameters on the target shape and heat load distribution have been studied. The robustness of the designed target has been investigated by simulation results with varying magnetic island configurations, confirming that the toroidal uniformity of heat load distribution is insensitive to changes in island configurations. Moreover, the designed target has been assessed with gas puffing of neon, which shows that neon injections effectively reduce the heat loads without altering the toroidal uniformity of heat load distributions. The proposed scheme highlights the importance of theoretical and mathematical foundations of target design, offering an advantageous alternative/complement to the traditional numerical schemes.

Two-component heterojunction-based ambipolar field effect transistors for improved sensitivity of ammonia sensor

To improve the sensing response of ammonia (NH3) sensors, a two-dimensional configuration molecule 5,11-di-naphthalen-2-yl-6,12-dihydro-indolocarbazole (ICZ-NA) was designed and synthesized as the p-channel organic semiconductor material. Bilayer organic field-effect transistor (OFET) was constructed with ICZ-NA and N,N’-bis(n-octyl)-2,6-dicyanonaphthalene-1,4,5,8-bis(dicarboximide (NDI-8CN2) as p-type and n-type active semiconductor materials respectively, and the two-component devices exhibits excellent ambipolar FET performance. The thin film transistors based on single-component and two-component were further used as sensors for ammonia detection. Compared with the sensors based on NDI-8CN2, the sensitivity and selectivity of ammonia detection based on two-component sensors have been greatly improved, and the ratio of current change can still be maintained over 3.65 %, when the gas concentration lower to 10 ppb level. The higher sensing response and low limit of detection demonstrate that the two-component ambipolar configuration is a highly effective method for improving sensing response capability.

Cellular automaton model of self-healing

We propose a simple cellular automaton model of a self-healing system and investigate its properties. In the model, the substrate is a two-dimensional checkerboard configuration which can be damaged by changing values of a finite number of sites. The cellular automaton we consider is a checkerboard voting rule, a binary rule with Moore neighborhood which is topologically conjugate to the majority voting rule. For a single-color damage (when only cells in the same state are modified), the rule always fixes the damage. For a general damage, when it is localized inside a 3 × 3 square, the rule also fixes it always. When the damage is inside of a larger n × n square, the efficiency of the rule in fixing the damage becomes smaller than 100 % , but it remains better than 98 % for n ≤ 5 and better than 75 % for n ≤ 7 . We show that in the limit of infinite n the efficiency tends to zero.

Rational Design Dithieno[3,2-f:2',3'-h]quinoxaline-Based Polymers with Optimized Molecular Configuration and Charge Transfer for High-Performance All-Polymer Solar Cells.

Due to poor planarity and weak intermolecular interactions of acceptor units which have two-dimensional configuration, the development of related polymers is slow. In this work, we synthesized a dithieno[3,2-f:2',3'-h]quinoxaline-based unit substituted with fluorinated thiophene, which can effectively expand the area of the acceptor unit. Then, it paired with three different benzodithiophene-based donor units, and three new polymers of PQTF-BT, PQTF-BTCl and PQTF-DTCl were obtained. PQTF-BT with thiophene side chain exhibits appropriate aggregation and crystallization performance, and the PQTF-BT:PY-IT all-polymer solar cells exhibit high device efficiency of 15.54%. Meanwhile, PQTF-BTCl with chlorination strategy on thiophene side chain further enhances the open-circuit voltage of related devices. However, it has negative impact on the miscibility and charge transfer of the material, leading to a poor efficiency of 8.71% in the PQTF-BTCl:PY-IT device. To reinforce miscibility, PQTF-DTCl with expanded backbone planarity was further studied. However, the big dihedral angles of the donor side chains disrupted the effective stacking of the molecules, resulting in great recovery of device performance to 13.42%. This work provides research ideas for the design of polymers with two-dimensional configuration side chain and match selection of donor units.

Highlighting the effects of gravity in a compact thermoacoustic heat pump

We present a numerical study of gravity impact on thermoacoustic heat pumping effects in a compact cavity used as a refrigeration device. More precisely, we show how gravity acts on the temperature distribution, on the mean temperature heat flux along the stack area and on flow dynamics. Studies are performed in a two-dimensional geometrical configuration which is simplified with respect to common experimental devices but sufficiently detailed to take into account the main physical mechanisms. Fluid motion, heat and mass transfer as well as compression/expansion effects are estimated from the computation of the Navier-Stokes equations in the low-Mach number hypothesis coupled with the heat equation in solid parts. The low-Mach number hypothesis is here relevant because the characteristic scale of the acoustic wavelength is much smaller than the geometrical length scales of the cavity. The operating mode is characterized by a moderate drive ratio, a fluid oscillating motion of moderate amplitude and fixed low frequency, typical of such devices. It is shown that when gravity is included, buoyancy effects modify the temperature and velocity fields as well as heat pumping efficiency.

Compressive properties and biocompatibility of additively manufactured lattice structures by using bioactive materials

Porous bioactive materials were widely used in orthopedic implant fields because of their excellent mechanical properties and porous spaces. However, most porous types are predominantly stacked in two-dimensional configurations, which significantly limits their mechanical property range and adversely affects the modulus matching between the porous implants and surrounding bone tissues. Hence, various lattice structures were prepared using 3D printing technology with bioactive materials, and characterized by mechanical and biological tests. Numerical simulations were conducted to analyze the effect of relative density and geometric parameters on the equivalent compressive properties of the lattice structures. The results showed that the lattice structure exhibited a broad elastic modulus range, which can be adjusted to align with the mechanical properties of human cortical and cancellous bones, thereby helping to mitigate stress shielding in orthopedic implants. The biocompatibility of the 3D-printed solid materials was assessed in vitro using a cell counting assay kit-8 (CCK-8). The results indicated that poly-ether-ether-ketone (PEEK), carbon fiber reinforced PEEK (CFR/PEEK), nylon, and titanium (Ti) alloy all exhibited good biocompatibility, with no significant differences observed among the four materials. This study further enhances the understanding of bioactive lattice structures in the biomedical field and offers new possibilities for orthopedic repair.

Hybrid Ising Machine and Reinforcement Learning Approach to Folding Lattice Proteins

The hydrophobic polarity (HP) protein folding model is a simplified computation model utilized to study the folding of proteins into their three-dimensional structures. Understanding how proteins fold and misfold is fundamental to designing effective, safe drugs, allowing for targeted therapies and better patient outcomes. The amino acids of a protein can be categorized as either hydrophobic or polar, where the hydrophobic beads tend to cluster together in a properly folded protein to minimize exposure to the surrounding environment. Determining the lowest energy configurations of the HP model is a non-deterministic polynomial (NP) hard problem. One method is formulating the HP model as a quadratic unconstrained binary optimization (QUBO) problem which can be mapped to an Ising machine. In the Ising model, the lowest energy state of the system represents the correct lattice configuration of the folded protein. The Ising machine technique utilized of simulated annealing allows for future application of the work on an integrated silicon photonic chip. Alternatively, reinforcement learning designed with an energy-based reward function can optimize the HP model by adapting to the environment without the consequence of remaining in local minima like that of the Ising machine. A hybrid pipeline combining the Ising machine and reinforcement learning sequentially was designed to determine the two-dimensional lattice configurations of various protein chain lengths and sequences, combining the parallel optimization of the Ising machine on an integrated photonic platform and the adaptability of the reinforcement learning algorithm. Results found that this hybrid model improved the accuracy and ability of determining the lowest energy state in contrast to the Ising machine alone as well as improved the efficiency by reducing the number of iterations required when compared solely to reinforcement learning. Future work focuses on implementing a parallel pipeline approach as well as adapting to a three-dimensional model.

Magnetite Nanoparticle Assemblies and Their Biological Applications: A Review.

Magnetite nanoparticles (Fe3O4 NPs) have garnered significant attention over the past twenty years, primarily due to their superparamagnetic properties. These properties allow the NPs to respond to external magnetic fields, making them particularly useful in various technological applications. One of the most fascinating aspects of Fe3O4 NPs is their ability to self-assemble into complex structures. Research over this period has focused heavily on how these nanoparticles can be organized into a variety of superstructures, classified by their dimensionality-namely one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) configurations. Despite a wealth of studies, the literature lacks a systematic review that synthesizes these findings. This review aims to fill that gap by providing a thorough overview of the recent progress made in the fabrication and organization of Fe3O4 NP assemblies via a bottom-up self-assembly approach. This methodology enables the controlled construction of assemblies at the nanoscale, which can lead to distinctive functionalities compared to their individual counterparts. Furthermore, the review explores the diverse applications stemming from these nanoparticle assemblies, particularly emphasizing their contributions to important areas such as imaging, drug delivery, and the diagnosis and treatment of cancer.

Spontaneous ignition and flame propagation in hydrogen/methane wrinkled laminar flames at reheat conditions: Effect of pressure and hydrogen fraction

Direct numerical simulations (DNS) with detailed chemical kinetics and chemical explosive mode analysis (CEMA) are performed to investigate the effect of operating pressure and hydrogen–methane blending on laminar wrinkled flames at reheat combustion conditions. Building upon previous three-dimensional DNS datasets of reheat hydrogen flames, the present work considers two-dimensional configurations that render computationally-feasible simulations of high-pressure combustion and significantly more complex hydrocarbon chemistry. A geometrically-simplified representation of the reheat combustor is adopted and the thermodynamic states considered in the simulations are carefully chosen to mimic gas turbine operation conditions, which are constrained to achieve a target flame position and flame temperature. The two-dimensional DNS results are first assessed against the available three-dimensional data and then analyzed to extract the main trends exhibited by the reheat combustion process with respect to the fraction of the fuel consumed by spontaneous ignition and flame propagation, for increasing pressures and hydrogen fractions. Due to significant differences in the characteristic features of the velocity and thermal boundary layers between the three-dimensional and the two-dimensional configurations, a different global flame shape is observed (V-shaped flame vs W-shape flame) together with a ∼10% bias in the fraction of fuel consumed by spontaneous ignition. Crucially, results from the scaling studies reveal very clear trends with a significant decrease in the fuel consumption by spontaneous ignition for increasing pressures and hydrogen fractions, at the conditions investigated. Finally, this study highlights the important role that first-principle direct numerical simulations, even when conducted in computationally affordable two-dimensional simplified geometrical configurations, can play in obtaining detailed insights and quantitative trends useful for the characterization of complex reactive flows.Novelty and significanceThe reheat burners of the two-stage sequential gas turbine combustors are designed to stabilize flames primarily due to spontaneous ignition. However, prior numerical simulations revealed the presence of an additional assisted-ignition mode aided by recirculation zones. In this study, we used practically feasible two-dimensional direct numerical simulations of premixed hydrogen–air mixtures under lean conditions to quantify the roles of the two flame stabilization modes at different operating pressures. Achieving fundamental understanding of the effect of pressure and hydrogen fraction on flame stabilization is crucial to the development of two-stage sequential combustion and the present two-dimensional calculations provide important new insights. We show that at high pressures, both modes consume fuel to a similar extent. We also investigated the effect of methane blending on flame stabilization. This study also discusses how two-dimensional direct numerical simulations can be leveraged in the design optimization of reheat burners at low technology readiness levels.

Understanding two-dimensional tractor magnets: Theory and realizations

We present a comparative investigation of two-dimensional tractor magnet configurations, analyzing both theoretical predictions and experimental results with a focus on the minimal tractor magnet. The minimal tractor magnet consists of a rigid assembly of one attracting magnet (attractor), two repelling magnets (repulsors), and a fourth magnet (follower) that is magnetically stabilized in a local energy minimum. The theoretical framework relies on magnetostatics and stability analysis of stationary equilibria. To calculate the magnetostatic force and energy, we use a multipole method. In a first approximation, we derive analytical results from the point dipole approximation. The point dipole analysis defines an upper bound criterion for the magnetic moment ratio and provides analytical expressions for stability bounds in relation to geometry parameters. Our experimental results are consistent with the predictions from the fourth-order multipole expansion. Beyond the minimal tractor magnet, we introduce a more advanced configuration that allows for a higher magnetic binding energy and follower capture at larger distances.

A fast algorithm for the two-dimensional Helmholtz transmission problem with large multiple scattering configurationsa).

We develop an efficient three-stage algorithm for simulating multiple acoustic scattering by two-dimensional configurations comprising large numbers of penetrable scatterers. Our approach is based on a boundary integral equation reformulation of the Helmholtz transmission partial differential equation, and a reduction of the boundary integral system for computationally efficient evaluation of wave interactions between scatterers. A key ingredient of our algorithm is to represent the interactions between scatterers using expansions of cylindrical wavefunctions. For large numbers of scatterers, this approach facilitates the application of the fast multipole method, leading to linear complexity of the algorithm with respect to the number of scatterers. Numerical results demonstrate the efficiency of our algorithm for configurations containing a few hundred to hundreds of thousands of individual scatterers.

Accelerated MPC: A real-time model predictive control acceleration method based on TSMixer and 2D block stochastic configuration network imitative controller

Modern industrial processes demand real-time model predictive control (MPC) method within the constraints of limited computing resources. This paper introduces an accelerated MPC method to address the issue. Specifically, we employ the time series mixing model (TSMixer) to construct a predictive model capable of accurately forecasting the behavior of the system under control. Furthermore, we extend the capabilities of TSMixer by integrating a feature classification model (TSMixer with FCM). This enhanced version takes into account both future information and static variables, resulting in superior accuracy compared to the transformer model while maintaining a significantly smaller parameter count. Finally, to further enhance MPC’s responsiveness, we develop a two-dimensional block stochastic configuration network (2D-BSCN) imitative controller. This innovative network clones the behavior of rolling optimization, effectively replacing online optimization to reduce computational time. The experimental results show that the accelerated MPC has an excellent performance in numerical simulation and actual industrial processes. Notably, the algorithm achieves a smaller FLOPs and tracking time than other state-of-the-art models, well within the requirement for industrial process control.

Quantum algorithm for solving the advection equation using Hamiltonian simulation

A quantum algorithm for solving the advection equation by embedding the discrete time-marching operator into Hamiltonian simulations is presented. One-dimensional advection can be simulated directly since the central finite-difference operator for first-order derivatives is anti-Hermitian. Here this is extended to industrially relevant multidimensional flows with realistic boundary conditions and arbitrary finite-difference stencils. A single copy of the initial quantum state is required and the circuit depth grows linearly with the required number of time steps, the sparsity of the time-marching operator, and the inverse of the allowable error. State-vector simulations of a scalar transported in a two-dimensional channel flow and lid-driven cavity configuration are presented as a proof of concept of the proposed approach. Published by the American Physical Society 2024

Effect of low blockage ratio obstacle on explosion characteristic in methane/air mixture

Methane/air explosion is one of the common hazards in process and mining industries. In this study, the methane explosion propagation is studied, and two-dimensional configuration is considered. The gas phase equations are solved using an OpenFOAM code for compressible reacting flow, EXiFOAM. The effects of the low blockage ratio (LBR) obstacles are investigated. The results show that the flame propagation speed, flame structure, shock wave propagation, and gas flow are considerably affected by LBR obstacles. Specifically, the flame propagation speed first increases and then decreases. As the initial pressure increases, the flame propagation speed gradually increases. The maximum speed is up to 500 m/s, when the initial pressure is 1.5 MPa. If the flame propagation is prevented, resulting in the flame deformation. Moreover, the flame disruptive phenomenon is captured due to the reflected waves. In front of the obstacle, the cellular structures of the high-pressure distribution are formed. Note that the tiny cellular structures are produced in the wake of the leading shock. Furthermore, a high-speed flow region and two low-speed flow regions are produced around the LBR obstacles. It is found that as the initial pressure increases, the explosion pressure is larger, while the temperature change is not obvious. These research findings have implications for enhancing safety production in coal mines.

Using exploratory graph analysis (EGA) in validating the structure of the Perth alexithymia questionnaire in Iranians with chronic pain.

Chronic pain's influence on emotional well-being can be significant. It may evoke feelings of despair, frustration, nervousness, and melancholy in individuals, which often manifest as reactions to enduring pain and disruptions in their daily lives. In this study, we seek to perform Bootstrap Exploratory Graph Analysis (EGA) on the Persian Version of the Perth Alexithymia Questionnaire (PAQ) in a cohort of people with chronic pain. The research concentrated on the population of individuals encountering chronic pain within Tehran province from 2022 to 2023. Ultimately, the analysis comprised information from 234 male participants (with a mean age of 30.59, SD = 6.84) and 307 female participants (with a mean age of 30.16, SD = 6.65). After data collection, statistical analysis was conducted using the EGAnet2.0.4 package in R.4.3.2 software. The outcome of bootstrapped EGA unveiled a two-dimensional configuration of the PAQ comprising Factor 1 denoted as negative difficulty in describing and identifying feelings (N-DDIF) and Factor 2 characterized as general-externally orientated thinking (GEOT), representing robust structural integrity and item consistency (all items have stabilities > 0.70). These findings endorse the validity of the PAQ, as evidenced by its confirmation in a broader sample using a novel methodology consistent with existing literature on two-factor decentering models.

Numerical modeling of shrinkage induced cracking in cementitious materials with three-dimensional simulation and phase-field method

This study investigates the damage and cracking of concrete induced by drying shrinkage. While previous studies have primarily focused on two-dimensional configurations, this research employs three-dimensional phase-field simulations of concrete samples undergoing the drying process. The distribution of inclusions is derived from tomographic images of real samples. The analysis includes the evolution of the damage field and the propagation of cracked zones. The study introduces the formulation and implementation of the numerical method and applies it to elucidate the cracking process resulting from drying shrinkage in concrete composites with various types of inclusions. Numerous numerical simulations were conducted to accurately depict the cracking process induced by drying shrinkage in the samples, evaluating the effects of different inclusions with varying stiffness on the concrete’s cracking phenomenon and comparing the impact of various energy degradation methods on crack simulation. Moreover, the study analyzes the influence of the spatial distribution of the inclusions in the three-dimensional simulation and compares the numerical results with experimental observations.

Three-dimensional zwitterionic hydrogel-based evaporators with simultaneous ultrahigh evaporation rates and anti-fouling performance

Zwitterionic hydrogels (ZHs) are commonly adopted as evaporators to address the issues of low evaporation rate and poor salt resistance in solar-driven interfacial desalination due to their unique anti-polyelectrolyte (AP) effect. However, the inherent limitations of ZHs, including low water transfer rates compared to their evaporation rates and poor mechanical properties, have restricted their applications to two-dimensional (2D) evaporator configurations. Herein, we proposed a unique design of three-dimensional (3D) composite solar evaporators based on ZHs and polyvinyl alcohol (PVA) sponge to improve the water transfer capacity and mechanical properties of ZHs, and thus achieve ultrahigh evaporation rates and excellent anti-fouling performance. The porous structure and super hydrophilicity of PVA sponge endowed the prepared 5-cm-high ZH-based solar evaporators (ZHSE) with water transfer rates significantly faster than those without PVA sponge. In addition, the elastic PVA sponge component enhanced the mechanical properties of ZHSE, allowing it to easily fabricate 3D structures to obtain higher evaporation rates. Moreover, PVA sponge barely weakened the AP effect of poly(sulfobetaine methacrylate) (PSBMA) hydrogels in the ZHSE. Consequently, the evaporation rate of ZHSE reached 4.66 kg m-2 h-1 at 3.5 wt%, one of the highest among previous reports, attributed to the contributions from the 3D structural design of the evaporator and AP effect of ZHs. Meanwhile, ZHSE showed outstanding anti-fouling properties and excellent shape stability, working in 20 wt% brine ten hours a day for ten consecutive days without noticeable salt deposition and volume shrinkage. This work provides a new route to design high-performance hydrogel-based evaporators with high water transfer rates.

Thin-airfoil aerodynamics in a rarefied gas wind tunnel: A theoretical study

We study the steady aerodynamic field and loadings about a thin flat plate placed in a wind tunnel under non-continuum conditions. Considering a two-dimensional straight tunnel configuration, the flow is driven by either density or temperature differences between the inlet and outlet tunnel reservoirs, producing a pressure gradient across the channel. Focusing on highly rarefied conditions, we derive a semi-analytic description for the gas flow field in the free-molecular limit for diffuse- and specular-wall configurations. The solution is valid at arbitrary differences between the inlet and outlet reservoirs as well as plate angles of attack α. The results are compared with direct simulation Monte Carlo calculations, indicating that the free-molecular description is valid through O(1) plate-size-based Knudsen numbers. The aerodynamic lift and drag forces are evaluated and their variations with α, reservoir conditions, and tunnel size are analyzed. At a fixed pressure ratio between the outlet and inlet reservoirs, the density-driven flow generates higher aerodynamic loads compared with its counterpart temperature-driven configuration, in line with the associated larger mass flow rate in the former. The results are discussed in light of the existing rarefied-gas description of the free-stream (non-confined) problem.

Dion-Jacobson perovskite solar cells: Further optimize the performance by SCAPS-1D simulation techniques

With rising global energy demands and the emergence of novel energy forms, perovskite solar cells (PSCs) are becoming increasingly prominent due to their exceptionally high efficiency in converting power. The advantage of Dion-Jacobson (DJ) type 2D layered perovskite materials lies in their lack of interlayer van der Waals forces, coupled with hydrogen bonds at the extremities, necessitating additional external energy to break through their two-dimensional layered configuration, thereby greatly enhancing the materials' structural integrity. This study utilizes DJ type 2D layered perovskite material to tackle the stability problem. This study aimed to uncover the inherent effects of DJ type 2D perovskite substances by simulating the devices with SCAPS-1D (Solar Cells Capacitance Simulator) and modifying appropriate physical parameters to align closely with the outcomes reported in experiments. Simulation results indicate that factors such as the thickness of the absorber layer, the band gap, the operating temperature, and the thickness of the interfacial defect layer uniquely influence the device's performance. The optimal thickness for the absorbing layer was determined by its ability to absorb light. The aim is to boost the sensitivity of DJ type 2D layered perovskite materials to light across various wavelengths and to refine the PCE. During the simulation, the maximum PCE (26.57%) was attained by enhancing both the band gap width in the absorber layer and the hole transport layer. To delve deeper into the fluctuations in device efficiency in environments with low temperatures, this study established the temperature spectrum between 270 and 300 Kelvin. Investigations revealed that at 272 K, the PCE and FF stood at 28.33% and 83.79% respectively, indicating the effectiveness of DJ type 2D layered PSC in low-temperature applications, preserving structural integrity and superior efficiency relative to other PSCs. Consequently, this study offers a viable approach for creating DJ type 2D layered PSC, ensuring high efficiency and enduring stability in cooler conditions.