Field Method Research Articles

Research on path planning based on improved artificial potential field method

Aiming at the unreachable target and local minimum problems existing in the traditional artificial potential field method in the path planning of mobile robots, an improved artificial potential field method is proposed. Firstly, when there are obstacles near the target point, the robot is difficult to reach the target point due to the large repulsive force. A safety distance factor is introduced in the potential field, and the parameter is optimized, so that the robot can maintain a suitable distance from the obstacle and reach the target point smoothly. Secondly, in order to solve the local minimum problem, the local minimum judgment condition is introduced, and when the condition is triggered, the local minimum area is bypassed, so that the robot can reach the target point smoothly. The simulation results show that the improved algorithm runs in the environment of different numbers of obstacles and has strong robustness. The proposed algorithm can enable the robot to bypass the local minimum area in the U-shaped obstacle environment, and successfully solves the local minimum problem in the path planning of mobile robots.

Incremental Cost Benefit Ratio (ICBR) of Poly House and Open Field Conditions in Cabbage (Brassica oleracea var. capitata) after Chemical Intervention

This study evaluates the Incremental Cost Benefit Ratio (ICBR) between Poly house and Open field conditions in cabbage cultivation chemical intervention. The research aimed to compare the economic feasibility of adopting poly house technology over traditional open field methods, considering costs and benefits associated with chemical inputs. A comparative cost analysis was conducted to assess production expenses like costs for insecticidal treatments and labor charges. Yield data from both environments were collected to determine output differences and subsequent economic returns. Results indicate that Incremental cost benefit ratio of cabbage heads yields to the cost of treatments in poly house and open field presented as there was a significant superior difference in ICBR ratio of poly house with 1: 0.946 as compared to open field with 1: 0.639 of cabbage heads. The economic analysis revealed that the higher yields and quality achieved in poly house conditions due to less dissipation and undisturbed environmental factors on insecticide applied. Resulting in a favorable incremental Cost benefit ratio compared to open field cultivation.

Semiclassical Nonadiabatic Molecular Dynamics Using Linearized Pair-Density Functional Theory.

Nonadiabatic molecular dynamics is an effective method for modeling nonradiative decay in electronically excited molecules. Its accuracy depends strongly on the quality of the potential energy surfaces, and its affordability for long direct-dynamic simulations with adequate ensemble averaging depends strongly on the cost of the required electronic structure calculations. Linearized pair-density functional theory (L-PDFT) is a recently developed post-self-consistent-field multireference method that can model potential energy surfaces with an accuracy similar to expensive multireference perturbation theories but at a computational cost similar to the underlying multiconfiguration self-consistent field method. Here, we integrate the SHARC dynamics and PySCF electronic structure code to utilize L-PDFT for electronically nonadiabatic calculations and use the combined programs to study the photoisomerization reaction of cis-azomethane. We show that L-PDFT is able to successfully simulate the photoisomerization without crashes, and it yields results similar to the more expensive extended multistate complete active space second-order perturbation theory. This shows that L-PDFT can model internal conversion, and it demonstrates its promise for broader photodynamics applications.

Digital image correlation and infrared thermography data for seven unique geometries of 304L stainless steel

Material Testing 2.0 (MT2.0) is a paradigm that advocates for the use of rich, full-field data, such as from digital image correlation and infrared thermography, for material identification. By employing heterogeneous, multi-axial data in conjunction with sophisticated inverse calibration techniques such as finite element model updating and the virtual fields method, MT2.0 aims to reduce the number of specimens needed for material identification and to increase confidence in the calibration results. To support continued development, improvement, and validation of such inverse methods—specifically for rate-dependent, temperature-dependent, and anisotropic metal plasticity models—we provide here a thorough experimental data set for 304L stainless steel sheet metal. The data set includes full-field displacement, strain, and temperature data for seven unique specimen geometries tested at different strain rates and in different material orientations. Commensurate extensometer strain data from tensile dog bones is provided as well for comparison. We believe this complete data set will be a valuable contribution to the experimental and computational mechanics communities, supporting continued advances in material identification methods.

Restricted Open-Shell Cluster Mean-Field theory for Strongly Correlated Systems.

The cluster-based Mean Field method (cMF) and it is second order perturbative correction was introduced by Jiménez-Hoyos and Scuseria to reduce the cost of modeling strongly correlated systems by dividing an active space up into small clusters, which are individually solved in the mean-field presence of each other. In that work, clusters with unpaired electrons are treated by allowing the α and β orbitals to spin polarize. While that provided significant energetic stabilization, the resulting cMF wave function was spin-contaminated, making it difficult to use as a reference state for spin-pure post-cMF methods. In this work, we propose the Restricted Open-shell cMF (RO-cMF) method, extending the cMF approach to systems with open-shell clusters, while not permitting spin-polarization. While the resulting RO-cMF energies are necessarily higher in energy than the unrestricted orbital cMF, the new RO-cMF provides a simple reference state for post-cMF methods that recover the missing intercluster correlations. We provide a detailed explanation of the method, and report demonstrative calculations of exchange coupling constants for three systems: a di-iron complex, a dichromium complex, and a dimerized organic radical. We also report the first perturbatively corrected RO-cMF-PT2 results as well.

Motion capture and AR based programming by demonstration for industrial robots using handheld teaching device

In the industrial robots field, efficient and convenient programming methods have been a hot research topic. In recent years, immersive simulation technology has been developing rapidly in many fields, which provides new horizons for the development of industrial robots. This paper presents a HTC VIVE laser scan motion capture and Holohens augmented reality (AR) based interactive Programming by Demonstration (PbD) system for industrial robot. A portable Handheld Teaching Device (HTD) and its calibration algorithm are designed in the system. The portable HTD which is tracked by a laser motion capture system can be viewed as an AR robot end-effector to teach paths. Meanwhile, the AR robot can be simulated in real time during programing. In addition, the robot reproducing the operator’s actions at the same position in space is the focus of programming. So, Multi-system registration methods are proposed to determine the relationship between robot systems, motion capture systems and virtual robot systems. Meanwhile, a path planning algorithm is proposed to convert the captured raw path points into robot-executable code. For unskilled operators, they can easily perform complex programming using the HTD. For skilled senior workers, their skills can be quickly learned by robots using the system.

Application of fluorescence spectroscopy as a field method in the determination of varietal differences radish (Raphanus sativus) accessions after harvesting

Application of fluorescence spectroscopy as a field method in the determination of varietal differences radish (Raphanus sativus) accessions after harvesting

Methodology for 3D sound synthesis of directional acoustic sources by higher-order ambisonics

This paper presents the 3D sound field synthesis using both the multimodal method and higher-order ambisonics (HOA) of the pressure field radiated by directional acoustic sources. Ambisonics is a technique for encoding and reproducing measured or modeled (virtual) sound pressure field, based on a decomposition of the acoustic field over spherical harmonics. The directional source considered in this work is an acoustic horn excited by a flat piston. The free-field radiation from this horn is first modeled accurately over a wide frequency range using the multimodal method, which requires relatively low computational resources. This radiated pressure field, collected on a dual-layer sphere of virtual sensors distributed over a Lebedev geometry, allows its projection into the ambisonic domain. The pressure field is then synthetized in the laboratory's 3D 5th order HOA spatialization sphere, which consists of fifty-six loudspeakers. This offers the ability of listening to the radiated sound using a higher-order ambisonic synthesis of a 'virtual' source before it is manufactured. To qualitatively evaluate the performance of the proposed procedure, the transfer function of the synthesized horn is measured around the listening point within the spatialization sphere. Key words : 3D sound synthesis, high-order ambisonics, directive sources, waveguides, horn, multimodal method

Study on frequency dependent convolution methods for sound event detection

Sound event detection (SED) aims to classify target sound events from a given audio clip with the corresponding onset and offset time localization. SED, a core research field in machine listening, has been rapidly growing by adopting the methods by applying deep learning methods in image recognition fields. One representative example is 2D convolution which is applied to 2D time-frequency audio features. However, 2D audio data exhibits physical discrepancies from 2D image data, one of which is that frequency dimension of 2D audio data is translational-variant while position dimension of 2D image data is translational-invariant. Therefore, to make 2D convolution more consistent to 2D audio data, we need to make 2D convolution dependent to frequency dimension. Previously, to address this problem, Frequency Dynamic Convolution (FDYConv) was proposed to replaces 2D convolution. FDYConv is dependent on frequency dimensions since it applies different kernels on frequency dimension. While it has proven its outstanding performance on SED, there are several more alternative frequency dependent convolution methods which are yet to be explored, In this work, we propose other simpler frequency dependent convolution methods and compare them with FDYConv in order to further investigate the effect of frequency dependence of 2D convolution methods.

Experimental identification of the bending stiffness and damping of plates using the frequency-adapted virtual fields Method

Inverse vibroacoustic methods can be used to identify the complex bending stiffness of a plate from its vibratory response. This work focuses on the Virtual Fields Method (VFM) and the Force Analysis Technique (FAT). The VFM uses functions called virtual fields to solve the Principle of Virtual Work, a weak form of equilibrium, and identifies complex bending stiffness. Here, the virtual fields are defined as piecewise functions over a surface smaller than the plate (virtual window). FAT uses a finite-difference scheme to discretize the fourth-order spatial derivatives of the displacement in the local equilibrium of the plate and thus estimates the bending stiffness. The application of a finite-difference scheme creates a bias in the identified stiffness, which increases with frequency. The Corrected Force Analysis Technique (CFAT) corrects this bias in the high-frequency domain. In this study, it is proposed to apply the CFAT principles to the VFM to adapt the method, using the virtual window size, so it can be applied it in the high-frequency domain. FAT, CFAT, the VFM and the Frequency-Adapted VFM will be presented. The method was tested on experimental data to identify the complex bending stiffness of an aluminium plate partially covered with a damping material.

Design of N-doped C60-σ-B-doped C60 photodetector based on resonant tunneling diode using DFT and NEGF method.

Photodetectors utilizing donor/acceptor (D/A) molecules have the capacity to detect light through molecular interactions between a donor and an acceptor molecule. These devices leverage electronic or optical changes within molecules when exposed to light, resulting in observable modifications. The unique properties of photodetectors with D/A molecules make them valuable tools in various fields, including molecular electronics. This paper presents the modeling and simulation of a single-molecule photodetector based on a D/A molecule configuration. The acceptor molecule used is N-doped C60 fullerene, while the donor molecule is B-doped C60 fullerene. Initially, simulations were conducted at zero bias voltage to determine the energy and states of the bipartite molecule. Subsequently, the system's Hamiltonian was computed based on these results. The self-consistent field method (SCF) and optical self-energy coefficients were employed for modeling. Finally, the current-voltage curve of the device was derived for various input light frequencies. The simulation and modeling results demonstrated that the device exhibited negative differential resistances at bias voltages of 0.33 V, 1.58 V, and - 0.93 V, depending on the input light frequency. Furthermore, the designed device demonstrated the ability to detect and absorb waves with different frequencies. The number of current peaks in the current-voltage curve varied with by altering the number of optical modes. The computational work was conducted using the software package of Atomistix ToolKit (ATK-2018.06) and MATLAB code. The calculations were based on the density functional theory (DFT) approach and the self-consistent field method, specifically the non-equilibrium Green function (NEGF). The exchange correlation function was investigated using the generalized gradient approximation (GGA) proposed by Perdew, Burke, and Ernzerhof (PBE). For the calculations, we employed the double-ζ plus polarization (DZP) basis set. Initially, the structures of N doped-C60-σ-B-doped-C60 molecule underwent optimization using the DFT approach implemented in the ATK package. This optimization process allowed us to extract the parameters of the molecule. Subsequently, we utilized the NEGF formalism in MATLAB software to model and simulate photodetector based on the optimized molecule. We calculated important features of the photodetector, such as photocurrent, and compared the performance of the photodetector using photons with energies of 2 and 3 eV.

Dialectical vernacular complicity: Navigating school choice and neoliberalism at a K-8 charter school in Phoenix, Arizona

ABSTRACT This paper joins past and ongoing conversations about the neoliberalization of public schools, via school choice and charter schools specifically. Using rhetorical field methods, a variety of data was collected over two years at a K-8 charter school in Phoenix, Arizona. Based on the data gathered, I propose dialectical vernacular complicity as a new concept that sheds light on the nuance and complexity of various agents’ (dis)engagements with neoliberalism. After defining the concept, the paper follows with a case study and concludes with reflections on the limits of agency with(in) neoliberalism, public education, and democracy.

Formative processes in nursing intervention in palliative care in internal medicine service patients

The purpose of the research project was to determine the nursing intervention in palliative care in patients of the Internal Medicine service of the Alfredo Noboa Montenegro Hospital during the period October 2023- February 2024, since nursing professionals are exposed to social, health and service changes, whose deficiency or lack of knowledge can limit an integral, personalized and quality intervention that allows care from individuality, flexibility, continuity, accessibility and polyvalence. A descriptive, cross-sectional, bibliographic and field method was applied with a quantitative approach, whose research design was non-experimental and cross-sectional, applying a sample by convenience with a total of 17 nursing professionals working in the internal medicine service, in addition, a survey of 29 questions distributed in four dimensions was used to collect the information; actions, education, psycho-emotional support, spiritual and grief. According to the results, it was possible to demonstrate the deficiencies of nursing professionals, especially in the identification of palliative needs, symptom assessment, intervention processes, use of tools to assess psychoemotional and spiritual needs, pharmacological approach and information on bereavement, which made it necessary to establish a palliative care guide focused on nursing professionals, to be subsequently socialized with all personnel.

Investigation of the sound insulation and natural ventilation performance of a metamaterial-based open window

Recent advancements in metamaterials have created new opportunities to enhance indoor environmental quality (IEQ) by integrating natural ventilation and sound insulation in architectural designs. Metamaterial-based windows can facilitate natural ventilation, contributing to energy savings while also protecting against outdoor noise. However, international standards for assessing façade sound insulation typically assume all partitions are closed, with only the Danish standard DS 447:2021 accounting for partially open conventional windows. These standards do not address simultaneous noise mitigation and natural ventilation. To fill this gap, this study evaluated a prototype metamaterial-based device called the Acoustic Metawindow (AMW) unit using three experimental methods. These methods included the diffuse field method (ISO 10140 series), an adapted directive sound field method (EN 1793-6), and beamforming to control sound leakages from the AMW unit in both closed and open states. Additionally, the study used an adapted ISO 9972 method to assess the ventilation potential alongside sound insulation of the open AMW unit. The findings revealed that the AMW unit significantly outperformed equivalently open windows, achieving a sound level difference (Dn,e) improvement of 5 to 15 dB in the 500-5000 Hz frequency range, resulting in a total Dn,e,w of 30 dB. The study also indicated a correlation between the frequency range of effective sound insulation and the metamaterial design features of the AMW unit. This research suggests the possibility of a more inclusive standard that considers partially open sound-insulating devices as windows in the built environment, combining noise mitigation and energy saving.

Optimization study of proton exchange membrane fuel cell parameters based on Taguchi method for central spiral flow field

Optimization study of proton exchange membrane fuel cell parameters based on Taguchi method for central spiral flow field

Unmanned vehicle off-road path-planning method with comprehensive constraints on multiple environmental factors

ABSTRACT In complex off-road environments, different slopes, slope directions, and land types differently affect unmanned vehicle trafficability. Thus, we propose an unmanned vehicle off-road path-planning method with comprehensive constraints on multiple environmental factors. First, the influence of slope, aspect, and surface-coverage type on unmanned vehicle drivability was quantitatively evaluated, and the slope and land type influence layers were formed. Concurrently, a goal guidance layer was formed using the artificial potential field method. Second, the slope influence, land type influence, and goal guidance layers were used to quantitatively evaluate each grid’s pass cost value. Finally, the traditional A* algorithm, A* algorithm considering the impassable area, A* algorithm with comprehensive constraints, and Dijkstra algorithm with comprehensive constraints were used for path planning. The results show that the path slopes planned by A* algorithm with comprehensive constraints and Dijkstra algorithm with comprehensive constraints were smaller than those planned by A* algorithm and A* algorithm considering the impassable area; particularly, the length of the uphill path was shorter and the stability was better. The relevant research results provide methods and technical guidance for obtaining the shortest length, shortest time, and most stable and passable path in off-road environments.

Gravitational scattering and beyond from extreme mass ratio effective field theory

We explore a recently proposed effective field theory describing electromagnetically or gravitationally interacting massive particles in an expansion about their mass ratio, also known as the self-force (SF) expansion. By integrating out the deviation of the heavy particle about its inertial trajectory, we obtain an effective action whose only degrees of freedom are the lighter particle together with the photon or graviton, all propagating in a Coulomb or Schwarzschild background. The 0SF dynamics are described by the usual background field method, which at 1SF is supplemented by a “recoil operator” that encodes the wobble of the heavy particle, and similarly computable corrections appearing at 2SF and higher. Our formalism exploits the fact that the analytic expressions for classical backgrounds and particle trajectories encode dynamical information to all orders in the couplings, and from them we extract multiloop integrands for perturbative scattering. As a check, we study the two-loop classical scattering of scalar particles in electromagnetism and gravity, verifying known results. We then present new calculations for the two-loop classical scattering of dyons, and of particles interacting with an additional scalar or vector field coupling directly to the lighter particle but only gravitationally to the heavier particle.

Spatial and frequency identification of the dynamic properties of thin plates with the Frequency-Adapted Virtual Fields Method

Vibroacoustic inverse methods use the measured response of a vibrating structure to identify a structural parameter or a dynamic load. Two inverse methods are considered, the Force Analysis Technique (FAT) and the Virtual Fields Method (VFM). The Corrected Force Analysis Technique (CFAT) is a variant of FAT that corrects its singularity. This correction allows the method to be applied in the high-frequency domain, when the number of measurement points per flexural wavelength becomes small. In this study, the proposed novelty is the development of a Frequency-Adapted VFM (FA VFM) to the case of a Love–Kirchhoff plate. Thanks to this method, the VFM can now be applied to identify the equivalent bending stiffness and structural damping of a thin plate when the number of measurement points per wavelength is small. The method has previously been developed for an Euler–Bernoulli beam. An experimental identification of the complex bending stiffness of an locally damped aluminium plate using Laser Doppler Velocimetry (LDV) data and the developed method is performed. The experimental study shows for the first time that the FA VFM can be used to map the equivalent bending stiffness and structural damping as a function of position on a plate and identify these parameters as a function of frequency over a large frequency band. The results of the Frequency-Adapted VFM are compared with those of CFAT and the classical VFM approach. FA VFM results are more accurate than those of classical VFM and similar to those of CFAT.

ASSESSMENT AND MAPPING OF THE MUDFLOW PHENOMENA INTENSITY IN CHARYN STATE NATIONAL NATURAL PARK

The aim of the article is to present the results of assessing the occurrence intensity of mudflow phenomena in the territory of the Charyn State National Natural Park (SNNP). The assessment and mapping of mudflow phenomena was carried out using field methods, comparative analysis of field materials, and a cartographic method. Based on indicators such as lithological composition of rocks, vertical dissection, surface slope and vegetation the assessment using number score was carried out and map of the territory of the Charyn SNNP was created. Thus, areas of tourist and recreational activity are susceptible to a high degree of mudflow phenomena.

Wind turbine foundation ring fatigue reliability analysis under wind-load using SCADA system

Under the action of wind load, the foundation ring of the fan will generate stress concentration and alternating stress, leading to fatigue failure. Based on the average wind speed obtained from the supervisory control and data acquisition (SCADA) system, the orthogonal expansion method of random pulsating wind field and the number theory point selection method are used to calculate and simulate the corresponding pulsating wind speed time series, and then calculate the wind speed time series and wind load time series. Based on the ABAQUS finite element software, a model of a 5 MW wind turbine is established. The modal analysis is used to obtain the modal vibration pattern and the intrinsic frequency to verify the reasonableness of the structural modeling. Subsequently, the wind load time series is applied to the wind turbine model to obtain the stress time series using instantaneous modal dynamic analysis (Modal dynamics). The stress time series at the location of maximum stress concentration in the foundation ring is extracted, and the stress time series with the same stress amplitude is obtained through conversion, which has Wiener characteristics. After obtaining the stress amplitude using the rainflow counting method, the fatigue reliability is calculated based on the structural fatigue reliability analysis method considering the threshold crossing duration of the random process. This research holds reference significance for the calculation of fatigue reliability under approximate working conditions.