Three-dimensional Field Distribution Research Articles

Investigation of collagen reconstruction mechanism in skin wound through dual-beam laser welding: Insights from multi-spectroscopy, molecular dynamics simulation, and finite element multiphysics simulation

Since the mechanism underlying real-time acquisition of mechanical strength during laser-induced skin wound fusion remains unclear, and collagen is the primary constituent of skin tissue, this study investigates the structural and mechanical alterations in collagen at temperatures ranging from 40 °C to 60 °C using various spectroscopic techniques and molecular dynamics calculations. The COMSOL Multiphysics coupling is employed to simulate the three-dimensional temperature field, stress-strain relationship, and light intensity distribution in the laser thermal affected zone of skin wounds during dual-beam laser welding process. Raman spectroscopy, synchronous fluorescence spectroscopy and circular dichroism measurement results confirm that laser energy activates biological activity in residues, leading to a transformation in the originally fractured structure of collagen protein for enhanced mechanical strength. Molecular dynamics simulations reveal that stable hydrogen bonds form at amino acid residues within the central region of collagen protein when the overall temperature peak around the wound reaches 60 °C, thereby providing stability to previously fractured skin incisions and imparting instantaneous strength. However, under a 55 °C system, Type I collagen ensures macrostructural stability while activating biological properties at amino acid bases to promote wound healing function; this finding aligns with experimental analysis results. The COMSOL simulation outcomes also correspond well with macroscopic morphology after laser welding samples, confirming that by maintaining temperatures between 55 °C–60 °C during laser welding of skin incisions not only can certain instantaneous mechanical strength be achieved but irreversible thermal damage can also be effectively controlled. It is anticipated that these findings will provide valuable insights into understanding the healing mechanism for laser-welded skin wounds.

Numerical study of TRISO particles with random size and location distribution in cuboid and cylindrical matrix: A validation for two-regime heat conduction model

During reactor operation, the precise size values or specific size distribution of tri-structural isotropic (TRISO) fuel particles randomly dispersed within the fully ceramic microencapsulated (FCM) fuel elements are often unknown. To investigate the impact of the random distribution of positions and sizes of TRISO particles within a cuboid or cylindrical matrix on the temperature distribution of fuel elements and to establish a practical heat conduction model, TRISO fuel particles with randomly distributed positions, diameters following Gaussian or uniform distributions are generated using relevant algorithms. A cuboid and a cylindrical TRISO fuel element are modeled in ANSYS, and a three-dimensional temperature field distribution of the fuel element is obtained through numerical simulation. The probability density of the maximum temperature of the fuel element is calculated and fitted. Finally, the applicability of the two-regime heat conduction model over a broader range is validated based on the simulated data. The conclusions of this study provide reference information for predicting the temperature distribution of FCM fuel elements containing TRISO particles with random size and location distribution.

Analysis of Acousto-Optic Phenomenon in SAW Acoustofluidic Chip and Its Application in Light Refocusing.

This paper describes and analyzes a common acousto-optic phenomenon in surface acoustic wave (SAW) microfluidic chips and accomplishes some imaging experiments based on these analyses. This phenomenon in acoustofluidic chips includes the appearance of bright and dark stripes and image distortion. This article analyzes the three-dimensional acoustic pressure field and refractive index field distribution induced by focused acoustic fields and completes an analysis of the light path in an uneven refractive index medium. Based on the analysis of microfluidic devices, a SAW device based on a solid medium is further proposed. This MEMS SAW device can refocus the light beam and adjust the sharpness of the micrograph. The focal length can be controlled by changing the voltage. Moreover, the chip is also proven to be capable of forming a refractive index field in scattering media, such as tissue phantom and pig subcutaneous fat layer. This chip has the potential to be used as a planar microscale optical component that is easy to integrate and further optimize and provides a new concept about tunable imaging devices that can be attached directly to the skin or tissue.

Thermal Modeling and Analysis of Hybrid-Magnetic-Circuit Variable Flux Memory Machine

Variable flux memory machine (VFMM) can be regarded as a promising candidate for electric vehicles (EVs) owing to its advantages of excellent flux adjustment capability and overall efficiency improvement over an extended operating range. However, the uncertain internal thermal behavior due to magnetization state (MS) change has an immense influence on electromagnetic performance of permanent magnet, which makes the precise MS estimation of low coercive force PM a challenging issue. To explore the benefits of MS manipulation on temperature rise reduction and provide an effective method to accurately evaluate temperature rise in VFMM, a magnetic-thermal coupling model of the newly developed hybrid-magnetic-circuit VFMM accounting for different MSs is established in this article. The lumped parameter thermal network (LPTN) model and computational fluid dynamics based finite-element (FE) method are employed to analyze the temperature characteristics, respectively. First, the losses of the investigated machine are calculated by adopting both the FE method and analytical equations. Afterward, the equivalent thermal resistances and heat transfer coefficients are determined by employing the LPTN model. Meanwhile, FE modeling is employed to analyze the three-dimensional thermal field distribution. Finally, a prototype machine is fabricated and experimentally measured, which can confirm the validity of the theoretical analyses.

Study on Stratified Settlement and Weak Reflectivity Fiber Grating Monitoring of Shield Tunnel Crossing Composite Strata

This paper proposes a set of field test technology system for layered settlement of composite strata based on weak reflectivity fiber Bragg grating sensing technology based on the shield project of “Keyuan Station ~ Shenzhen University Station” section of Shenzhen Metro Line 13, and through the comparison and verification of three-dimensional numerical simulation and field monitoring, the law and distribution characteristics of disturbance settlement of ground surface and overlying strata during shield tunneling are systematically analyzed, and the vertical and horizontal zoning (layer) system for the spatial and temporal evolution of layered settlement of composite strata during shield tunneling is constructed. On this basis, the targeted settlement control technical measures and recommendations are proposed. The findings show that the weak reflectivity fiber grating sensing technology can better perceive the evolution law and distribution characteristics of vertical and horizontal settlement of composite strata caused by shield tunneling, which is in good agreement with the numerical simulation results, and has the advantages of automation and high precision, it can be used as a supplement and alternative method for traditional measurement methods. The stratum deformation is small and layered settlement is not obvious in shield approaching stage (−5D~0), after shield crossing and shield tail falling (0~3D), the stratum is the longitudinal main deformation zone of shield tunneling disturbance, and the influence range of the whole tunneling disturbance is about (−1D~3D). Meanwhile, according to the influence degree of shield tunneling disturbance, the overlying strata of the tunnel can be divided into main disturbance layer and secondary disturbance layer, and the main disturbance layer is located in the range of 0.5D above the tunnel. In addition, based on the different stages of shield tunneling and the vertical and horizontal zoning (layers) of existing structures such as buildings (structures), the settlement control measures and suggestions are proposed. The research results demonstrate the feasibility of weak reflectivity fiber grating for distributed and continuous strata monitoring. It has important guiding value for improving the understanding of settlement law produced from shield construction in composite strata and analyzing and predicting potential risks resulting from shield construction. It also provides reference value for future subway design and construction.

High-precision gaseous flame temperature field measurement based on quadriwave-lateral shearing interferometry

Quadriwave-lateral shearing interferometry (QLSI) has a broad utilization in quantitative phase imaging (QPI) for refraction-type objects due to its compact structure and stable performance against external disturbance. Here we propose to use the QLSI technique to image and measure the gaseous flame temperature field distribution in high precision. The quantitative phase image of an axisymmetric candle flame is firstly reconstructed from the wire-mesh-like QLSI interferogram, and then the three-dimensional temperature field distribution is calculated with the axisymmetric projection transform algorithm. Compared to the conventional digital holographic interferometry (DHI) based on Mach-Zehnder architecture, the proposed method possesses a high-precision measurement and better stability in disturbed environment, benefiting from the compact common-path structure of QLSI. The temperature measurement errors of the proposed QLSI method are ±5.0 K and ±5.3 K in the presence of airflow disturbance and mechanical vibration, respectively, while those of the DHI method are ±7.6 K and ±12.9 K, respectively.

Anti Crystallization Blocking of Flocking Drainage Pipe Based on Natural Phenomenon

Crystalline pipe plugging of the tunnel drainage system was one of the causes of tunnel lining cracking and water leakage. Effective prevention of crystalline pipe plugging of tunnel drainage pipe was very important to ensure the safety and stability of lining structure during tunnel operation. Using the methods of field investigation, indoor model test and numerical simulation, a new flocking anti crystallization blocking technology was proposed. The crystallization law and anti-crystallization efficiency of the flocked drainage pipe at different flow rates, the three-dimensional flow field distribution characteristics and the crystal distribution law of flocking drainage pipe were studied. The results show that the maximum crystallization rate of nonflocked drainage pipe was 1.30 g/d. The maximum stable attachment amount of crystals in flocked drainage pipe was 18.13 g, and the maximum anti crystallization efficiency can reach 80 %. The flocked drainage pipe can preferentially select the villus with the length of 5 mm and 10 mm. The flow velocity at the top of flocked drainage pipe increased by 35 %. Crystals near the water inlet of flocked drainage pipe were mainly distributed on both sides, near the water outlet were mainly distributed in the middle and lower part of the drainage pipe, and were attached to the wall surface of the drainage pipe at the water outlet. Flocked parameters of flocked drainage pipe (flocking material, flocking length, flocking diameter, flocking longitudinal spacing and flocking circumferential spacing, etc.) also need a lot of experimental research, so that the research results can truly solve the practical engineering problems.

Simulation Research on Tightening Force and Temperature Distribution of Tension Clamps in Distribution Network

In order to study the effect of tightening torque on the temperature change of overhead line tension clamps and conductors, a structural model of NLL-4 tension clamps was established using COMSOL Multiphysics. Under the power frequency of 400-650A, the electromagnetic-thermal coupling finite element simulation analysis of the tension clamp was carried out by adjusting the tightening torque, and the three-dimensional temperature field distribution of the tension clamp and the wire was obtained. The results show that when 600A power frequency alternating current is applied, the tightening torque decreases continuously, and the overall temperature of the tension clamp and wire increases with the decrease of the torque. When the tightening torque is constant, different power frequency AC currents of 400-650A are applied, and the overall temperature of the tension clamp increases with the increase of the current; at the same time, no matter how the current and tightening torque change, the temperature of the extrusion part of the wire is always higher than the temperature of the unextruded part.

Design Consideration of AC Hybrid-Excitation Permanent-Magnet Machine With Axial Stator Using Simplified Reluctance Network

In this article, we deal with design considerations of a new ac hybrid-excitation permanent-magnet machine with axial stator. Due to the presence of an axial stator, the machine features a typical three-dimensional geometric structure and field distribution. A simplified reluctance-based network is developed to capture the main design features of the machine. The analytical equations are deduced relating the main geometric dimensions to the machine design criteria: speed, power, and flux regulation capability. The influence of key machine geometric parameters, i.e., radial/axial air-gap length, stack length, and bore diameter, on output power, flux density, and flux regulation capability is investigated. It is found that there is a design tradeoff between the machine power density and flux regulation capability. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> / <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis inductance and its ratio, which has an influence on flux weakening capability and operation performance, is examined. Finally, a 6-pole/36-slot prototype is built. Intensive experimental tests are carried out to verify the machine characteristics.

Dynamic Modeling and Control for Tilt-Rotor UAV Based on 3D Flow Field Transient CFD

The tilt-rotor unmanned aerial vehicle (TRUAV) is characterized by both multi-rotor vertical takeoff or landing and fixed-wing long-duration flight. Not only the structure of TRUAV is complex, but also the aerodynamic coupling is severe. Especially when the TRUAV is in the transition mode, the rotor flow field and wake are complicated. The abnormal variation of the aerodynamic force of the rotor blades will directly affect the balance and manipulation of the aircraft. The downwash flow generated by the rotor spiral propeller tip vortex interference will impact the wing from every direction, forming a blocked three-dimensional effect flow field on the wing surface, which seriously affects the stability of the UAV. In this paper, the transient CFD (Computational Fluid Dynamics) numerical simulation was applied to examine the flow fields of the fuselage and rotor under the transition modal of TRUAV as well as the aerodynamic disturbance. In addition, the dynamics model of the TRUAV was established based on the change of the tilt angle state, and considering the effect of rotor slip flow, we analyzed the three-dimensional flow field distribution of TRUAV in the transition mode under the aerodynamic disturbance of the fuselage and rotor, and we identified each aerodynamic parameter required for modeling. A cascade PID control strategy is designed for the TRUAV, and the results verify that the proposed TRUAV model can remain stable even when the maximum roll angle is 20 degrees. At last, the simulation results provide data support for the optimization of the TRUAV aerodynamic profile and the design of subsequent flight control methods.

Quantitative evaluation of defects based on the characteristics of the induced eddy current field

A quantitative evaluation method for determining the shape, length and depth of surface defects is proposed for the purpose of non-destructive testing (NDT) and evaluation of metal materials. The COMSOL Multiphysics finite element software is used to calculate and analyse the eddy current magnetic field and the influence of the geometric parameters of defects on the spatial three-dimensional magnetic field distributions are studied. The results show that the shape of the surface defect can be judged from the measurement result of the x-Bx curve. The quantitative analysis of the crack length is realised according to the corresponding position of the peak (trough) of surface magnetic field Bz . The depth of the crack can be inversely calculated by the quantitative relationship between the trough depth of Bx (or the peak value of Bz) and the crack depth. Therefore, this method provides convenient and contactless detection technology in which the characteristic quantities corresponding to the defect parameters are independent from each other to improve the accuracy of defect evaluation.

Flame 3D temperature field reconstruction based on Damped LSQR-LMBC

Light field camera can solve the problems of complex optical path and difficult synchronous trigger of radiation temperature measurement multi camera system, which has some unique advantages in three-dimensional temperature reconstruction of radiation imaging. The LSQR is a classical algorithm for solving the least square problem based on large sparse matrix. When the algorithm is used to reconstruct three-dimensional temperature field, it depends on the initial value of temperature, and the reconstruction accuracy is not ideal when the signal-to-noise ratio is low. In this paper, a damped LSQR-LMBC reconstruction algorithm is proposed. By adding a damped regularization term into the LSQR method, the anti noise performance of flame three-dimensional temperature field reconstruction is improved. By combining the LMBC algorithm, the absorption coefficient and three-dimensional temperature field are solved at the same time. In the numerical simulation part, with the gradual reduction of signal-to-noise ratio, the reconstruction effect of Damped LSQR turns more stable than LSQR. When the signal-to-noise ratio reaches 13.86 dB, the reconstruction accuracy is improved by about 30%. The average reconstruction error of damped LSQR-LMBC is 6.63%. The three-dimensional temperature field distribution of butane flame is consistent with the characteristic of radiation flame combustion. Compared with the temperature measurement data of thermocouple, the relative error is about 6.8%.

Analysis of the mechanical performance and damage mechanism for 3D printed concrete based on pore structure

3D printed concrete (3DPC) technology is one of the fastest-growing technologies in the construction industry. In this study, the pore structure of 3DPC and its parameters were investigated. The variation patterns of compressive strength, splitting tensile strength, and flexural strength of 3DPC were studied with the increase of curing time in different loading directions. Characterisation of the meso-destructive mechanism and ultimate strength of 3DPC by X-ray computed tomography (X-CT) and the digital image correlation (DIC) techniques is conducted. The results showed that the internal pore structure of 3DPC was different from that of cast concrete, showing irregular shapes and the pores were prone to stress concentration, resulting in the mechanical strength of 3DPC being generally lower than that of cast specimens. Moreover, the mechanical strength of 3DPC showed significant anisotropy. 3DPC showed variability in the relationship between its pore structure and strength when compressed in the X-, Y- and Z-directions. The ultimate compressive strength of 3DPC and its damage mechanism were analysed based on the parallel pore connection model. The three-dimensional stress field distribution at the 3DPC interface was predicted when the cracks extend along the direction parallel or perpendicular to the interface.

Simulation calculation and comparative analysis of three-dimensional temperature field of ultra high voltage through wall bushing under different current carrying capacity

As the key equipment of UHV transmission and transformation line, UHV bushing needs to carry the ultra-high voltage and large current of UHV power system at the same time. When the operating temperature of UHV bushing is too high, the operation failure rate will increase significantly, which will affect the stability and safety of UHV transmission line. Therefore, it is particularly important to analyze the temperature field characteristics of UHV bushing. This paper takes UHV bushing as the research object. The finite element software is used to calculate the electro thermal coupling. The three-dimensional thermal field distribution characteristics of UHV bushing are simulated and analyzed. This paper analyzes the influence of eddy current on the temperature distribution of UHV bushing under operation condition, and discusses the influence degree of eddy current on the temperature distribution of bushing, which provides an important basis for the temperature distribution, structure improvement and operation maintenance of bushing.

Determination of the Leakage Reactance of End Windings of a High-Power Synchronous Generator Stator Winding Using the Finite Element Method

The paper presents a description of the method and the results of calculating the leakage reactance of high-power synchronous generator end windings using the finite element method. This reactance is one of the components of the stator leakage reactance of synchronous generators. The calculations were carried out under the assumption of a three-dimensional field distribution in a synchronous generator. The thus calculated value of the leakage reactance of the end windings was compared with the calculation results obtained using traditional, analytical formulas known from the literature. The analysis of the influence of the reactance value of the end windings on the transient waveforms at a three-phase short-circuit of the stator windings was performed based on a two-dimensional field-circuit model.

Study on Temporal and Spatial Characteristics of Overlying Strata in the Deep Coal Mining Process

This study adopts the stress relief method to test the in situ stress in the field to obtain the in situ stress distribution characteristics of no. 2 + 3# coal seam. A three-dimensional model was established with the no. S3012 working face as the engineering background, and the measured in situ stress values were applied to the three-dimensional model, and the spatial-temporal evolution characteristics of coal and rock mass around the stope during coal seam mining were studied. The specific conclusions are as follows: the three-dimensional stress distribution map in front of, behind, and on both sides of the working face in the process of coal mining are obtained. As the working face goes on, the maximum value of the supporting stress formed in front of, behind, and on both sides of the working face shifts to the corner, presenting a “hump-like” distribution. The stress concentration coefficient of front, back, and both sides of stope increases linearly with the increase of the mining size. Under the same mining size, the stress concentration coefficient in front of stope is the smallest, and the stress concentration coefficient on both sides is the largest. The three-dimensional displacement field distribution nephogram of overlying strata in the process of coal mining is obtained. With the continuous advance of the working face, the roof strata of coal seam undergo the continuous dynamic subsidence process, and the roof subsidence increases continuously, showing the shape of “bowl” with sharp bottom. In the process of working face mining, the roof displacement of coal seam showed an “O” shape evolution characteristic. The three-dimensional distribution cloud map of the plastic zone of coal and rock mass in the process of the working face mining was obtained, and the failure volume of the plastic zone gradually increases with the continuous progress of the working face.

Effect of fault zone and natural fracture on hydraulic fracture propagation in deep carbonate reservoirs

The Shunbei oil and gas field is located in the low uplift of Shuntuoguole, which is affected by the multistage tectonic movement of the basin. There are several strike-slip fault systems that have developed from north to south, and the geological characteristics of the reservoir are controlled by different combination of fault zones. A large cavernous fracture system is developed in the main fault zone. The stress inversion calculation and analysis methods are established for various types of faults. The three-dimensional stress field distribution in the study area was obtained through numerical simulation. The magnitude and direction of the stress field were analyzed at different depths and locations in different types of faults, including at the tip, in the middle, adjacent to the fault, and in the intersection to determine the magnitude and spatial distribution behavior of the stress field in the multi-fault area around the well. On the basis of the stress field simulation, the distribution of some natural fractures is preliminarily explained according to the statistical fracture distribution behavior, and a hydraulic fracturing process simulation is performed to reveal the distribution and influence range generated by hydraulic fracturing, which provides guidance for subsequent hydraulic fracturing scheme designs.

The heat flow coupling effect of laser-assisted magnetorheological polishing

During the magnetorheological polishing process of concave workpieces, the magnetorheological fluid tends to accumulate at the entrance of the polishing zone, resulting in a decrease in the polishing efficiency and quality. To solve this problem, in this paper, laser-assisted magnetorheological polishing technology was proposed. Based on the theory of fluid mechanics and heat transfer, a three-dimensional temperature field distribution model of the spherical polishing film was established to achieve local temperature control at the entrance of the polishing zone. Then, the functional relationship between the viscosity of the magnetorheological fluid and the temperature was obtained experimentally. On this basis, the shear force and hydrodynamic pressure models of the polishing zone were established, which reveal that the heat flow coupling effect can increase temperature at the inlet of the polishing zone and reduce the viscosity of the local magnetorheological fluid, thereby reducing the shear stress in the polishing zone. The results show that when the laser power is 3 W and the magnetorheological fluid flow rate is 6 ml/s, the viscosity of the magnetorheological fluid at the entrance can be effectively reduced, and the shear force in the polishing zone decreases slightly.

Effect of slot end faces on the three-dimensional airflow field from the melt-blowing die

Abstract In order to investigate the effect of the slot ends of the melt-blowing die on the three-dimensional airflow field distribution and the fiber draft, the numerical calculation was carried out. The computational domain of the slot die was established with Gambit, and the flow field was calculated using FLUENT. Compared with the experimental data collected by a hot-wire anemometer, the numerical calculation results are credible. The results show that the slot end face has a certain influence on the three-dimensional flow field distribution under the melt-blowing die. The air velocity and temperature in the center region are quite different from those near the slot-end face. As the distance from the center of the flow field increases, the velocity and temperature on the spinning line begin to decrease. The velocity and temperature distributions of the spinning lines in the central area and nearby areas are almost the same; the temperature and velocity values on the spinning lines near the slot end are the lowest. The distribution characteristics of the three-dimensional airflow field could affect the uniformity of the fiber diameter and the meltblowing products.

Towards polarization-based excitation tailoring for extended Raman spectroscopy.

Undoubtedly, Raman spectroscopy is one of the most elaborate spectroscopy tools in materials science, chemistry, medicine and optics. However, when it comes to the analysis of nanostructured specimens or individual sub-wavelength-sized systems, the access to Raman spectra resulting from different excitation schemes is usually very limited. For instance, the excitation with an electric field component oriented perpendicularly to the substrate plane is a difficult task. Conventionally, this can only be achieved by mechanically tilting the sample or by sophisticated sample preparation. Here, we propose a novel experimental method based on the utilization of polarization tailored light for Raman spectroscopy of individual nanostructures. As a proof of principle, we create three-dimensional electromagnetic field distributions at the nanoscale using tightly focused cylindrical vector beams impinging normally onto the specimen, hence keeping the traditional beam-path of commercial Raman systems. In order to demonstrate the convenience of this excitation scheme, we use a sub-wavelength diameter gallium-nitride nanostructure as a test platform and show experimentally that its Raman spectra depend sensitively on its location relative to the focal vector field. The observed Raman spectra can be attributed to the interaction with transverse and pure longitudinal electric field components. This novel technique may pave the way towards a characterization of Raman active nanosystems, granting direct access to growth-related parameters such as strain or defects in the material by using the full information of all Raman modes.