Slot Width Research Articles

Influence of Slot Width in Cartridge on Crack Propagation and Energy Concentration Under Explosion Load

Influence of Slot Width in Cartridge on Crack Propagation and Energy Concentration Under Explosion Load

Response study of impact of slot area variation in miniature antenna for Kurtz-Above band applications in 5G/6G wireless communication

Modern fifth-generation/sixth generation (5G/6G) wireless demand for efficient miniature antenna. To fulfill these demands here efforts have been made using high frequency structure simulator software (HFSS) to design a compact microstrip patch antenna (MPA). The design of the antenna consisted of two slots- one located near the feed line and the other one at the opposite side of the feed line. The volumetric dimension of the proposed antenna was 13.2 mm x 11.4 mm x 1.6 mm, designed at resonant frequency 33 GHz, employing 1.6 mm thick Rogers RT Duroid 5880 substrate having dielectric constant 2.2 and loss tangent 0.0013. A transmission line having a length of 5.7 mm and a width of 2 mm was used to excite the antenna for electromagnetic radiation fields. Antenna parameters simulation results were obtained for different slot areas, keeping other design parameters like dimensions of ground, patch, substrate, and feed port fixed. Different slot areas were selected by changing slot width, keeping its length constant. A gain of 7.7 dB with voltage standing wave ratio (VSWR) of 1.9 and return loss (S11) -19.23 dB was obtained for slot width 3 mm and area 1.5 mm2. The directivity of the antenna was reported as 5.7dB, with a very good surface current density of 104.94 Amp/m, considered sufficient in the fringing fields breaking situation. Bandwidth was found to be inversely proportional to slot width. VSWR, S11, and 3D gain showed inverse dependence on slot area. Gain and S11 change in direct proportion to feed width whereas VSWR changes inversely with feed length. The proposed MPA is suitable for satellites, mobile phones, wireless communication systems, and remote sensing applications.

Multi-Objective Optimization Strategy for Commercial Vehicle Permanent Magnet Water Pump Motor Based on Improved Sparrow Algorithm

In order to achieve multi-objective optimization for a permanent magnet water pump motor in heavy commercial vehicles, we propose a strategy based on response-surface methodology and the improved sparrow algorithm (CGE-SSA). Firstly, the output capacity of the pump during actual operation was tested with an experimental bench to determine the design parameters of the motor, and then its modeling was completed using Ansys Maxwell 2022r2 software. Secondly, the response-surface model was established by taking the parameters of permanent magnet width, rib width, and slot width as optimization parameters and the output torque (Ta), torque ripple (Tr), and back electromotive force (EMF) amplitude as optimization objectives. Meanwhile, three methods—namely, circular sinusoidal chaotic mapping, improved golden sinusoidal strategy, and adaptive weight coefficients—were used to improve the convergence speed and accuracy of the sparrow search algorithm (SSA). Finally, the multi-objective optimization of the permanent magnet synchronous motor was completed using the improved sparrow algorithm. A comparative analysis of the motor’s output before and after optimization showed that the torque pulsation and reverse electromotive force of the motor were significantly improved after optimization.

Research on Performance of Interior Permanent Magnet Synchronous Motor with Fractional Slot Concentrated Winding for Electric Vehicles Applications

The fractional-slot, concentrated-winding, interior permanent magnet synchronous motor (FSCW IPMSM) has advantages, such as reducing motor copper consumption, improving flux-weakening capability, and motor fault tolerance, and has certain development potential in application fields such as electric vehicles. However, fractional-slot concentrated-winding motors often contain rich harmonic components due to their winding characteristics, leading to increased motor losses and back electromotive force harmonics, thereby affecting the efficiency and constant power speed regulation range of the motor. Based on this, this article first uses the winding function method to explore the inductance and saliency ratio of the interior permanent magnet synchronous motor with different slot pole combinations in the fractional-slot concentrated- winding of electric vehicles. Secondly, this article will establish a 2D finite element parameterized model to analyze and compare the performance of fractional-slot concentrated-winding motors with different slot pole combinations, including air gap magnetic density, back electromotive force distortion rate, overload multiple, and torque. The structural parameters of the motor were optimized with the objective of minimizing the torque ripple under the constraint of minimizing the average torque reduction. The motor slot width, permanent magnet angle, and permanent magnet pole arc angle were analyzed and optimized. The simulation results showed that 12 slots and 8 poles were the optimal design schemes, providing a theoretical basis for the selection of slot pole coordination in the fractional-slot concentrated-winding interior permanent magnet synchronous motor for electric vehicles.

Efficient and broadband sound absorption properties of slotted aluminum foam

To enhance the sound absorption performance of aluminum foam, a slotted structure was developed. Firstly, the theoretical model of sound absorption for the slotted aluminum foam was established by the transfer matrix method. Secondly, the finite element model was established using COMSOL software to predict the sound absorption coefficient. The reliability of the theoretical and finite element models was validated through impedance tube experiments. The sound absorption mechanism is investigated by analyzing the internal sound field. Finally, the sound absorption properties of aluminum foam with other slot patterns are investigated. Additionally, the factors that influence sound absorption properties are investigated. The results indicate that the slots alter the sound pressure distribution within the material, inducing a pressure diffusion effect. When sound waves enter the interior of the material through the narrow slots, they are absorbed and dissipated by the matrix material on the sides of the slots. The sound absorption coefficient can be improved by increasing the thickness, slot scale, and slot depth of the slotted aluminum foam. Specifically, when the slot depth is 15 mm, and the slot width is 5 mm, the average sound absorption coefficient of incompletely slotted aluminum foam in the frequency range of 1000 ∼ 6300 Hz is 0.86, which can realize broadband sound absorption. With the increase of slot depth, the sound absorption peak becomes more pronounced.

Optimization of Graphene-based Antenna using Metasurface for THz Applications using Ensemble Learning models

Aims and Background: These days, communication is governed by scaled-down devices with extremely high data transfer rates. The days of data transfer rates in megabytes are long gone and the systems are touching data speeds of hundreds of gigabytes. To cater to this requirement, the evolution of metasurface-based antennas working in the THz frequency range is gaining pace. Objectives and Methodology: Metasurface layers in antennas have unique mechanical and electrical properties that make them feasible. Graphene is a preferred metasurface material when designing antennas. In this paper, two novel designs of graphene-based metasurface antennas are proposed. These patch antennas with graphene metasurface layers have two configurations for slotted patches. Both graphene and gold-slotted patches are tested in this paper, and results are presented and validated for various performance parameters like return loss, peak gain, peak directivity, and radiation efficiency. Results: The design of the proposed Graphene Patch Antennas (GPA) is done in HFSS, and once the design is complete, the data is collected for variations in antenna parameters and is further processed via machine learning for better convergence in terms of return loss using ensemble learning. Optimal tuning of antenna components like substrate length, patch length, slot width, etc., is done using two regressor algorithms viz Histogram-based Gradient Boosting Regression Tree (HBDT) and Random Forest Tree (RFT) in machine learning. The radiation efficiencies of the two designs presented in this work are 89.04%, 97.54%, an average radiation efficiency of of 93.29%. The bandwidth of the two antenna designs is 8.63 THz and 8.69 THz, respectively. Conclusion: Experimental results indicate that the proposed designs are achieved better bandwidth, and radiation efficiencies compared to state-of-art designs.

Optical inspection of stator slots for electric motors

An optical non-contact inspection system was developed for measuring the slots in stator lamination stacks. To avoid passing go/no-go gage blocks through the slots, a machine vision system is instead used to measure the stator core slots and identify the presence of burrs within the slots. Utilizing telecentric optics along with an alignment monitoring system configured to monitor and orient the stator core, the core slots can be oriented relative to the imaging axis for further metrology measurements. Among these measurements, the smallest opening dimensions (slot width and depth) of each slot due to misalignment of laminations and the detection of burrs along the edges of the slots throughout the length of the lamination stack are critical for full stator assembly. Advanced image processing algorithms were developed to obtain sub-pixel accuracy which is required to measure the slots. This, used in conjunction with a robust vision calibration technique, increases the feasibility of building a device that can be implemented as a production inspection system. Experiments show the reliability of the computer vision approach and how it can be used in the inspection of slots in lamination stacks.

Experimental investigation on propagation characteristics of rotating detonation wave fueled by diesel

Diesel fuel plays an indispensable role in the energy power sector. Detonation is a self-pressurizing combustion mode that can improve the utilization efficiency of diesel fuel. Through experiments, this paper explored the propagation characteristics of diesel/air RDWs within three different air-inlet slot width structures. A total of 24 high-pressure atomizing nozzles were evenly distributed circumferentially to inject diesel fuel into the combustor. The air, preheated by a heater, was injected into the combustor through the air-inlet slot. The results demonstrate the successful achievement of diesel/air rotating detonation under three different air-inlet slot width structures. As the width increases, the range of operating conditions for achieving detonation becomes more limited. As the air temperature rises, so does the detonation wave's propagation velocity, reaching up to 79 % of the theoretical CJ value. Both single-wave and two-wave collision modes were obtained in the experiments, with a constantly shifting collision point of the two-wave mode, forming the drift phenomenon. The establishment time for the detonation wave is comparatively short, ranging from 2.0 to 5.5 ms, and is minimally affected by the air-inject slot width and the total air temperature. The two-wave collision mode evolved from the single-wave form.

Three-dimensional numerical investigation on flow and heat transfer characteristics and multi-objective optimization of interconnected microchannels

The interconnected microchannel demonstrates excellent performance in enhancing flow heat transfer. However, the optimal width of the interconnecting slot has not been thoroughly investigated. To address this gap, this paper numerically simulates the three-dimensional flow and heat transfer of interconnected microchannels featuring varied slot widths and channel depths. The investigated slot widths range from 50 to 1000 μm and depths of 100, 200, and 300 μm. Evaluation of overall performance encompasses heat transfer and flow characteristics such as average wall temperature, heat transfer coefficient, thermal resistance as well as pressure drop. It is the interconnected slots that interrupt the velocity and thermal boundary layers, contributing to enhanced heat transfer. Furthermore, the back propagation neural network and non-dominated sorting genetic algorithm-II are utilized for multi-objective optimization of thermal resistance and pressure drop. The technique for order preference by similarity to an ideal solution (TOPSIS) method combined with the entropy weight method is employed to select the compromise optimal solution from the Pareto optimal solutions. The optimized slot widths are 369, 424, and 167 μm for channel depths of 100, 200, and 300 μm, respectively. This research provides data support for the optimization design and engineering manufacturing of interconnected microchannels.

Simulation and Experimental Design of Magnetic Fluid Seal Safety Valve for Pressure Vessel

This article focuses on the safety valve of pressure vessels, and a new ferrofluid sealing device for pressure vessel safety valves is developed based on a special magnetic circuit. A combined method of numerical calculation and experimental analysis is used to study the relationship between seal clearance, number of seals, pole slot width, pole tooth height, pole tooth width, and the sealing pressure of the ferrofluid sealing device. The research results show that seal clearance and pole tooth width have a significant impact on the sealing performance, and as the dimensions increase, the sealing pressure decreases. As the number of seals, pole tooth height, and slot width increase, the sealing performance initially improves and then decreases. This phenomenon is attributed to the increase in magnetic reluctance in the magnetic circuit. In experimental studies, when the excitation current of the electromagnet is 240 mA and the coil turns number 30, the sealing capacity is 61.22 kPa. When the excitation current is 200 mA and the coil turns number 80, the sealing capacity is 168.24 kPa. The experiments demonstrate the compensating ability of magnetic fluid seals in combination with safety valve seals, confirming that combined seals have higher reliability compared to conventional mechanical seals.

Longitudinal-Torsional Frequency Coupling Design of Novel Ultrasonic Horns for Giant Magnetostrictive Transducers.

The use of advanced brittle composites in engineering systems has necessitated robotic rotary ultrasonic machining to attain high precision with minimal machining defects such as delamination, burrs, and cracks. Longitudinal-torsional coupled (LTC) vibrations are created by introducing helical slots to a horn's profile to enhance the quality of ultrasonic machining. In this investigative research, modified ultrasonic horns were designed for a giant magnetostrictive transducer by generating helical slots in catenoidal and cubic polynomial profiles to attain a high amplitude ratio (TA/LA) and low stress concentrations. Novel ultrasonic horns with a giant magnetostrictive transducer were modelled to compute impedances and harmonic excitation responses. A structural dynamic analysis was conducted to investigate the effect of the location, width, depth and angle of helical slots on the Eigenfrequencies, torsional vibration amplitude, longitudinal vibration amplitude, stresses and amplitude ratio in novel LTC ultrasonic horns for different materials using the finite element method (FEM) based on the block Lanczos and full-solution methods. The newly designed horns achieved a higher amplitude ratio and lower stresses in comparison to the Bezier and industrial stepped LTC horns with the same length, end diameters and operating conditions. The novel cubic polynomial LTC ultrasonic horn was found superior to its catenoidal counterpart as a result of an 8.45% higher amplitude ratio. However, the catenoidal LTC ultrasonic horn exhibited 1.87% lower stress levels. The position of the helical slots was found to have the most significant influence on the vibration characteristics of LTC ultrasonic horns followed by the width, depth and angle. This high amplitude ratio will contribute to the improved vibration characteristics that will help realize good surface morphology when machining advanced materials.

Characteristic analysis of the vortex excited using the photoacoustic transducer with a spiral light absorption surface

Abstract It is proved that the vortex acoustic field can be excited with laser by designing the photoacoustic transducer with a spiral light absorption surface. The generated acoustic field has a spiral phase wavefront, and the pressure on the central axis along its propagation direction is zero. The orbital angular momentum that can be used for positioning and manipulation of particles is formed by the vortex. The characteristics of the generated acoustic vortex at different frequency and detection position are analyzed for 1-5 topological charge. And the influence of the geometric configurations such as the width and size of logarithmic spiral slot are also studied for the achieving the desired vortex field with focused intensity.

Investigations on Penta Band High Isolation MIMO Antenna for 5G NR Bands and HIPERLAN Applications Using TCMA

The present article proposes a penta band Multiple Input Multiple Output (MIMO) antenna for 5G New Radio (NR) bands and HIPERLAN applications using Characteristic Mode Analysis (CMA). The design is obtained and optimised in step-by-step procedure using novel CMA approach and by perturbing the conventional rectangular structure with slots on the patch (left and right sides) and the ground plane (wide slot + narrow slots) for enhancing the isolation at multi bands. The MIMO configuration has a total dimension of 0.58 l0 × 0.35 l0 × 0.01 l0 mm3 with an optimum element separation of 0.05 l0 (l0 is the lowest frequency operating wavelength). Multiband resonance is produced at 2.2, 4.2, 7.2, 16, 17.5 GHz. The radiating elements can excite various characteristic modes that support wider bandwidth. The -10 dB impedance bandwidth at working region are 0.2, 0.2, 0.38, 3.6, 2 GHz respectively. The suggested design yields a gain of 2.1, 5.7, 3.5, 3.5, 5.2 dBi and consistent radiation patterns at the working frequencies. The analysis of the diversity performance considers the Diversity Gain (DG) and Envelope Correlation Coefficient (ECC), whose values are near 9.9 dB and 0, respectively. Additionally, the assessed parameters are the CCL and TARC. The structure prototype has been developed, and the observed findings are highly coherent with the simulated results, making it appropriate for use in 5G NR bands, HIPERLAN, and IoT applications.

Analysis and Suppression of Spoke-Type Permanent Magnet Machines Cogging Torque with Different Conditions for Electric Vehicles

Spoke-type permanent magnet (STPM) machines have high power density and low cost due to flux concentrated effect and high air-gap flux density, but they can cause high cogging torque and torque ripple. To reduce the cogging torque, the analytical model considering a rotor slot is established and compared with the finite element mothed (FEM). Then, the cogging torque production mechanism is revealed and analyzed under different conditions, which provides direction to optimize the cogging torque STPM machines. The harmonic content of cogging torque under different conditions is obtained based on the freezing permeability (FP) method. It is found that the fundamental waves mainly generate the cogging torque under a no-load condition, and it is mainly generated by the second harmonics under an on-load condition. In addition, the optimization method is introduced and researched, including rotor slot width, uneven rotor core, and so on. Finally, a 50 kW STPM machine prototype is manufactured and tested to verify the accuracy and efficiency of the analysis method.

Experimental and Theoretical Studies of Nano-Silica Solutions in Narrow Flow Paths Applied to Sealing Cement Cracks

Summary A cement crack is a typical cause of oil and gas well failure. Cracks weaken cement, reducing zonal isolation and fluid leakage. Nanoparticle (NP) gels are being tested for fracture treatment. When crushed into cracks, the flow behavior of NP problem solutions should be predicted. The potential efficacy of utilizing NP gels as a remedial measure for fractures is currently under investigation. It would be advantageous to determine if the flow behavior of solutions for NP problems can be anticipated when they are compressed into crevices. This study aimed to analyze the behavior of nano-silica solutions as they flow through ducts with rectangular cross-sections and varying crack dimensions. The introduction of NP solutions into the core leads to a decrease in pressure, which suggests that the nano-silica has been effectively transported through the crack. As the size of the fracture decreases, there is a corresponding increase in pressure drops, while the flow rate experiences a concurrent increase. This study presents responses of a pressure gradient to fluid concentration for a range of fracture widths, heights, and flow rates. The prediction of laminar flow in ducts is based on the linear correlation between the flow rate and the pressure gradient. Furthermore, the reduced pressure gradient indicates enhanced fluid flow within the fracture because of the amplified slot width. The fluid flow model proposed by Guo et al. (2022) was utilized to conduct a comparative analysis with the experimental data. Compared with test data, the model differs by roughly 90%. The technical cause of the flow model-observed data discrepancies is unknown. The flow model did not account for friction between NPs-NPs and NPs-walls in rough ducts. An empirical correlation has been found that quantifies the ratio as a function of nonsilica solution flow rate, cross-sectional geometry parameters, and nano-silica concentration. The correlation was calculated using nonlinear regression. The empirical relation and actual ratio have a significant correlation, as shown by R2 = 0.8965. In practice, Guo et al.’s (2022) hydraulic model’s pressure drops should be multiplied by the empirical correlation’s ratio to reduce errors.

Second harmonic generation enhancement based on quasi-BICs in centrosymmetric materials

In centrosymmetric optical materials, the second-order nonlinear polarization of the bulk electric dipolar contribution is zero. More effective utilization of the contribution of the surface term is one of the key methods to efficiently obtain second-order nonlinear responses on these materials. Herein, a design of densely packed slotted nanopillar arrays based on quasi-bound states in the continuum (quasi-BICs) is proposed. The quasi-BICs are analyzed by using the finite element method as an example of silicon and the second harmonic generation (SHG) process is simulated. In the structure, normal-incidence linearly polarized light excites magnetic dipole-like quasi-BICs with a high quality factor which effectively promotes light-matter interactions. Increasing the nanopillar radius or decreasing the lattice constant within a certain range can cause the distribution of quality factors in k-space of the ky direction to contract toward the Γ point, which leads to a quasi-BIC with higher quality factors at the Γ point. By conjunctively adjusting the nanopillar radius and lattice constant or changing the slot azimuth, the resonance wavelength can be adjusted over a wide range (about several hundred nanometers) or finely (within about one nanometer) while maintaining high quality factors. When the symmetry perturbation introduced by the slot is small, it is calculated that the SHG conversion efficiency is about 10−6∼10−5 at an incident light power density of 1 MW/m2, and the SHG power is about 107∼108 times enhancement compared with the structure without slots. As the slot width decreases, higher SHG conversion efficiency with more significant SHG enhancement can be achieved at a specific slot length. The results provide new insights into the modulation of the resonant wavelength and quality factor of quasi-BICs, as well as the control of second-order nonlinear effects in centrosymmetric materials.

Generation of cubic Hermite spline-based trochoidal milling toolpath by introducing a coefficient factor in machining curved slots

Trochoidal milling has become popular in high-speed milling due to its ability to reduce cutting force, enhance thermal dissipation, and prolong tool life. Among other toolpath patterns, the cubic Hermite spline offers significant advantages in generating trochoidal milling toolpath in machining complex and curved slots. However, determining those two different relation coefficients in the polynomial function of cubic Hermite spline remains complicated and empirical. This paper introduces a coefficient factor to simplify the determination process, which only requires the position and tangent vector parameters of each endpoint pair. The coefficient factor combines an instantaneous in-process slot width (IISW)-related width factor and a tangent vector direction-related direction factor. Two complex-curved slots are used to validate the performance of the proposed method. The results show that this method is straightforward and effective in generating trochoidal milling toolpaths for machining complex-curved slots while matching the slot geometry. Additionally, compared with a direct 5-axis trochoidal milling (one-step slotting strategy) in trochoidal milling of 3D slots on both serial and hybrid machining tools, a two-step slotting strategy (3-axis trochoidal milling and a successive 5-axis perpetual milling) is preferable in improving machining efficiency.

The effect of forming surface interference on Thin-Walled profiles during the discontinuous forming process with discrete molds

This study aims to investigate the influence of the roller dies’ characteristics of shapes on the forming results in the roller-based flexible multi-point three-dimensional stretch bending forming (FSBRD) process for thin-walled profiles, as well as the prediction of mold-induced impressions during the FSBRD process. Considering the specific contact mode, an L-shaped section profile’s flange was selected as the research object to analyze the impact of the roller dies’ slot’s geometric parameters on the product. A classification model of the contact between the profile’s flange and the roller die was established for the vertical bending process, and the maximum theoretical interference value (imax) was calculated to predict the extent of local deformation after contact. Subsequently, finite element software was used to model the process and analyze the changes in equivalent plastic strain (PEEQ) of the deformation results when using roller dies with slots of different parameters, including straight, inclined, and arc-shaped slots. The analysis results indicate that the width of the straight slot has a significant influence on the forming quality of the product, as a smaller slot width leads to larger local dimples on the product surface. Replacing the straight slot with an inclined or arc-shaped slot improves the abrupt changes in local PEEQ, resulting in reduced macroscopic local dimples. The simulation results align with the analytical model’s variation of imax. This study defined the theoretical contact angle γ and introduced the concept of the contact area and the local theoretical interference zone, providing a reasonable explanation for the observed PEEQ variations. Furthermore, based on the conclusions of the research above, modified experiments were designed, resulting in favorable forming effects. The validation of the simulation results was performed by comparing the local dimples in the contact zone of the actual experimental results.

Grinding performance of MgF2 ceramics using biomimetic shark fin grinding wheels with different structure parameters

In the field of precision machining, with the popularity of brittle and hard materials such as infrared windows, it has become difficult for conventional diamond grinding wheels to effectively perform high-quality machining. The structuring of traditional diamond grinding wheels using a pulsed laser is a key technology to effectively improve the grinding quality of grinding wheels. In this paper, three new shark fin diamond grinding wheels (SFSGW) with different slot widths are designed based on the excellent drag-reducing and channelizing properties of shark dorsal fins. The grinding performance of traditional grinding wheels (USGW) and SFSGW on magnesium fluoride ceramics was compared. The effects of SFSGW on the surface quality, surface roughness and wheel damage of the workpiece were investigated. The results showed that the surface roughness of ceramics after grinding by SFSGW was reduced by 22.15 % compared with USGW, and the surface quality was better. Proper construction increases the material removal rate of the wheel and improves the wear resistance and service life of the wheel.

Influence of fluidic shock control on the combustion flow field of a dual-mode scramjet

To improve the resistance capability of a dual-mode scramjet isolator, fluidic shock control devices with different control parameters were designed. First, the effects of the control parameters on the position distribution, morphological structure, evolution process of the shock train in the isolator and the resistance capability of the isolator were numerically simulated. Then, cold- and hot-state tests of the scramjet through a direct-connected pulse combustion wind tunnel were carried out at a simulated flight Mach number of 4 to obtain the ignition and combustion process in the scramjet combustor under fluidic shock control through measurements by high-speed schlieren and pressure transducers. Finally, the influence of fluidic shock control on supersonic combustion was analysed by comparing the flow field structure and combustion process with and without a control device at different equivalent ratios and under different fuel injection schemes. The results showed that the fluidic shock control parameters with a great influence on the resistance capability of the isolator were the angle and width of the suction slot and the angle of the injection slot and that the resistance capability of the isolator could be effectively improved by reasonably designing the control parameters. Under fluidic shock control, the morphological structure and positional distribution of the shock train showed an obvious hysteresis evolution process near the injection slot and the suction slot in the isolator with increasing and decreasing back pressures, and this hysteresis effect could further improve the combustion performance of the combustor.