Slot Shape Research Articles

Optimization of slot parameters for performance enhancement of slotted Savonius hydrokinetic turbine using Taguchi analysis

Hydrokinetic technology is an innovative approach to generate sustainable energy from river systems by using the kinetic energy of free-flowing water. To utilize such energy hydrokinetic turbines are being employed to harness the kinetic energy from flowing water. In this paper, a CFD study has been carried out to improve the efficiency of the Savonius turbine with the application of proposed slotted blades and validated with the experimental study. Also, this study aims for the optimization of a slotted blade Savonius hydrokinetic turbine (SHT) performance by examining different design parameters and their relationship using the Taguchi method. This study reveals that slot gap (y) has the greatest influence on turbine performance, followed by slot shape factor (ε), slot position (f), and tip speed ratio (λ). Moreover, the optimal combination of four parameters for maximising the efficiency of the slotted SHT is y = 1.5 mm, ε = 0.6, f = 1 % of blade diameter, and λ = 0.7 based on signal-to-noise (S/N) ratio. At this optimum combination of slotted blade profile, performance of slotted blade SHT increases by 45.19 % compared to conventional SHT. There is a slight difference of 4.16 % between experimental and computational results obtained for optimum Taguchi design.

Self‐Assembling Design Method of Stator Slots for AC Rotating Machines

To maximize the performance of rotating machines, it is essential to establish a design method with minimal arbitrariness. This paper proposes a self‐assembling method to design stator slots for alternating current (AC) rotating machines. First, we develop a line‐current approximation model of the stator winding using pulse‐width modulation technique and realize an ideal spatial magnetic flux density distribution. Subsequently, we design the realistic stator with an acceptable current density of the winding by forming unique slot shapes in a self‐assembling manner under two synthetic conditions using the developed line‐current approximation model as the starting model. The designed stator realizes a rotating magnetic field similar to the conventional design results. Additionally, we perform an analysis of motor rotation characteristics by combining the self‐assembled stator with a surface‐mounted permanent magnet rotor to determine the possibility of a higher output compared to that when using a conventional stator. The self‐assembled motor without relying on empirical rules shows a possibility of further improving the torque characteristics, thereby contributing to designing the AC rotating machines. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Design a metamaterial based applicator for hyperthermia cancer treatment

This research describes a metamaterial-based applicator with and without water bolus for cancer treatment. The metamaterial based applicator consists of a double spiral antenna and a slotted square shape artificial magnetic conductor (SSA) structure. The antenna is designed on a low-cost FR4 substrate with dimensions of 32 × 32 × 3.27 mm3, and the SSA unit cell which behaves as a metamaterial, is designed on an RT-duroid substrate with dimensions of 15 × 15 × 0.76 mm3 (size of the unit cell). The 4 × 4 unit cells of the SSA structure are optimized to direct the maximum field toward the cancer tissue. The proposed applicator (antenna + SSA structure) is tested for hyperthermia treatment using a heterogeneous phantom (skin, fat, and muscle layers) and the human-mimicked model with an air medium and a water bolus layer. The applicator’s performance is evaluated in terms of specific absorption rate (SAR), penetration depth (PD), and effective field size (EFS). Further, thermal analysis is performed, with 1.5 W of input power at the antenna port, and the maximum temperature rise of 44 0C is obtained. The cancer tissue (tumor) temperature ranges between 41 °C to 45 °C, sufficient for effective hyperthermia therapy. Finally, the suggested metamaterial based applicator is built and tested in the presence of a phantom and head tissue simulating liquid.

Design of Vibration and Noise Reduction for Ultra-Thin Cemented Carbide Circular Saw Blades in Woodworking Based on Multi-Objective Optimization

Cemented carbide circular saw blades are widely used for wood cutting, but they often suffer from vibration and noise issues. This study presents a multi-objective optimization method that integrates ANSYS and MATLAB to optimize the design of noise reduction slots in circular saw blades. A mathematical model was developed to correlate the emitted sound power with the overall vibration intensity. A multi-objective optimization model was then formulated to map the slot shape parameters to the deformation, equivalent stress, and vibration intensity during sawing. The ABAQUS thermal–mechanical coupling analysis was used to determine the sawing force and temperature field. The NSGA-II algorithm was applied on the ANSYS–MATLAB platform to iteratively compute slot shape parameters and conduct optimization searches for a globally optimal solution. Circular saw blades were fabricated based on the optimization results, and experimental results showed a significant reduction in sawing noise by 2.4 dB to 3.0 dB on average. The noise reduction effect within the specified frequency range closely agreed with the simulation results, validating the method’s efficiency. This study provides a feasible and cost-effective solution to the multi-objective optimization design problem of noise reduction slots for circular saw blades.

Microstrip Patch Antenna Performance Optimization by Variation in Position of Rectangular Shape Slot

Microstrip Patch Antenna Performance Optimization by Variation in Position of Rectangular Shape Slot

Numerical Analysis of Outer-Rotor Synchronous Motors for In-Wheel E-Bikes: Impact of Number of Windings, Slot, and Permanent Magnet Shapes

This study investigates the design an electric motor propelling hubless wheel mounted on an electric bicycle (e-bike) by numerical analysis. The motor is part of an in-wheel system that uses a permanent magnet synchronous motor (PMSM) to drive the hubless wheel. This paper presents an optimized PMSM design and compares various torque-related parameters, such as cogging torque, cogging torque total harmonic distortion (THD), and ripple torque. The comparison is based on a motor design that examines the effect of different factors, including the number of windings, slot openings, permanent magnet span, and magnet thickness. The motor was modeled and analyzed with variations in the number of windings (21, 23, 25), slot openings (2.4 mm, 3.0 mm, 3.6 mm), permanent magnet span (23 mm, 25 mm, 27 mm), and permanent magnet thickness (3.5 mm, 4.0 mm, 4.5 mm). Our findings suggest that increasing the permanent magnet’s thickness leads to a higher magnetic flux density. Additionally, when the permanent magnet span exceeds 25 mm, there is a sharp increase in cogging torque THD. Based on these results, a slot opening of 3.0 mm and the use of 25 windings are considered suitable for a hubless e-bike.

A Study on the Design of BLDC Motor for Air Conditioning and Characterization of Slot Shape for Torque Ripple Reduction

A Study on the Design of BLDC Motor for Air Conditioning and Characterization of Slot Shape for Torque Ripple Reduction

A design of compact wideband substrate integrated waveguide fractal koch surface slot antenna for Ka‐band applications

SummaryThis article analyses a substrate integrated waveguide (SIW) fractal koch surface (FKS) slot antenna performance for Ka‐band applications. This FKS slot shape is obtained by modifying the conventional rectangular slot with the first iteration of the FKS method. The resultant FKS slot behaves as a radiator in the provided space. A single‐ and two‐element FKS slotted SIW antenna characteristics are analysed on a 20 mil thick RT/Duroid 5880 substrate and compared with the conventional rectangular slot. The proposed antenna with dimensions mm3 achieves an impedance bandwidth from 27.4 to 32.1 GHz with a fractional bandwidth of 15.79% and achieves a gain of 8.3 dBi in broadside direction by improving space filling factor in SIW structure. The prototype of the SIW‐fed FKS slotted antenna array measurement results is satisfactory with the simulation results.

Wideband MIMO configuration with mutual coupling reduction and better isolation using the combination of electric field LC resonator and Swastik resembled structure

This work explains the design and development of a small, wide-ranging antenna for millimeter wave (mm-Wave) and 5G technology and their applications, along with the configuration to set up as a multiple-input multiple-output (MIMO) system. Rogers RT/duroid 5880 substrate material, which has a height of 1.575 mm, is used for fabricating the antenna. It possesses a compact overall size of 36 × 36 mm2. The design process began with the creation of a octagonal conventional mm-wave microstrip antenna. Subsequently, the impedance bandwidth was enhanced by incorporating the slots of rectangular shape on either parallel edges to the patch feed enabling it to perform over a larger bandwidth ranging between 25 GHz to 32 GHz. Moreover, a new metasurface and a structure shaped like a swastika are positioned between the 2 × 2 arrangement to minimize mutual coupling. The suggested MIMO antenna provides a wide frequency range, significant gain, minimal interference between antennas, and a low correlation between signal envelopes while also achieving a high level of diversity gain. Furthermore, the proposed study has been compared to similar works to demonstrate the significance of the proposed research.

Comprehensive investigation on the slot leakage inductance of axial flux permanent magnet motor with novel slot shape

Comprehensive investigation on the slot leakage inductance of axial flux permanent magnet motor with novel slot shape

Identification of the oversized rock pieces in hydraulic hammer breaking process based on the scanner data geometry features analysis

Due to the harsh conditions in the mining environment, it is difficult to fully automate some of the tasks carried out by mining machines and devices. As part of the technological process of extracting copper ore from Polish mines, the material is broken with a hammer to fit through the screen of a 40×40 cm square shape slot, after which it is loaded and conveyed for further processing. Usually, most of the material remaining on the screen cannot be considered oversized, additionally smaller particles can form blockages or rest on larger blocks. In this case, the crushing is not necessary, and only its movement may be sufficient. The focus of the presented research is on the identification of the particles that would be considered oversized, as it is a crucial task in the breaking hammer automation process. The authors propose a method based on the analysis of initially extracted 3D data copper ore blocks obtained from laser scanning at one of the transfer stations in KGHM Polska Miedź S.A., Polkowice-Sieroszowice mine. The difficulties of measurement are multiplied by the necessity of performing the scan from a single point of view, which was forced by safety concerns. Segmented but incomplete 3D data are processed, which results in finding the geometric features that prevent the material from going through the screen in an automatic manner.

A Compact Four Port High-isolation SIW-backed Self-quadruplexing Antenna with a Swastik Shaped Slot for C Band Applications

A Compact Four Port High-isolation SIW-backed Self-quadruplexing Antenna with a Swastik Shaped Slot for C Band Applications

CPW-Fed Monopole Antenna with L Shaped and Stair Shape Slot for Dualband WLAN/WiMAX Applications

CPW-Fed Monopole Antenna with L Shaped and Stair Shape Slot for Dualband WLAN/WiMAX Applications

Numerical-field analysis of the magnetic conductivity of the slot dispersion of the stator winding of induction motors

Introduction. The magnetic fields and the corresponding magnetic conductivities of the slot dispersion of the stator winding of three-phase induction motors (IM) are studied. Such studies are relevant in their design and are one of the bases for calculating a number of energy parameters and characteristics of motors. In the classical design of an IM, which is still valid, the specified magnetic conductivities are determined analytically according to the simplified slot dispersion model, therefore they may not always provide sufficient accuracy due to a number of assumptions and conventions. Goal. Further development of the IM design system by means of a numerical-field calculation analysis of the magnetic conductivity of the slot dispersion of their stator winding, as well as a comparative check of the relevant analytical formulas from various methods of classical design. Results. The slot dispersion of IM is determined by numerical calculations using the FEMM program within the stator tooth steps. For the research, four variants of the shapes of the stator slots, which are common in modern IMs of small and medium power, are accepted. In the calculations, calculation models with strongly saturated and unsaturated in the magnetic relation with the stator core teeth are considered. The numerical-field method shows that the classical design method can give both sufficiently accurate results and unacceptable errors in determining the magnetic conductivities of slot dispersion of IM. Discussion and prospects for further development. The provided numerical-field analysis method and the obtained results of the calculation of slot dispersion of IM windings are recommended as a basis for improving the system of their design.

Influence of the shape of the disc slots of the seeder on the suction force of the vacuum for precise sowing of seeds

Abstract The article analyzes the influence of the shape of the disc slots of the seeder on the suction force of the vacuum.Currently, pneumatic devices for various soil and climatic conditions are accurate with a cellular method of sowing seeds and the development of a seed drill design, in which 3 seeds are sown in each nest, targeted scientific research is being conducted to substantiate the parameters, ensuring its functioning at the level of agrotechnical requirements.In order to study the influence of the shape of the nests of the lander disk on the vacuum suction force, experimental studies were conducted using the lander disk of three different variants. Based on the conducted experiments, the authors drew their conclusions.

A penta‐band microstrip slot antenna for S‐, C‐ and X‐band applications

AbstractThis letter presents a compact penta‐band microstrip slot antenna. The proposed antenna comprises a microstrip feed line on the top plane, a polytetrafluoroethylene (PTFE) substrate, and a slotted ground plane. Different shapes of slots and two pairs of horizontal strips on the ground are introduced to achieve five frequency bands. A prototype is fabricated and measured to demonstrate the validity of the design. According to the measured result, the fabricated antenna can operate at five operating frequencies with an impedance bandwidth of 2.41–2.55 GHz (5.65%) for Bluetooth and WLAN, 3.31–3.58 GHz (8.14%) for WiMAX and Sub‐6 GHz 5G applications, 4.52–4.76 GHz (5.17%) for radiometry, 5.10–6.20 GHz (19.47%) for WLAN and ITS, and 10.14–12.40 GHz (20.10%) for radar applications. Moreover, the proposed antenna shows a bi‐directional radiation pattern at each operating band.

High Gain Metamaterial Implemented Antenna Design with Circular Polarization for mm-Wave 5G and 6G Sub-THz Communication

A high-gain metamaterial-enabled circularly polarized antenna has been proposed. Two patch structures patch A and patch B have been designed by using different shape slots. After slot etching on the patch, two different metamaterial techniques were used. Circular metamaterial (MTM) was implemented for Patch A, while rectangular MTM was used for Patch B. The implementation of MTM resulted in increased antenna gain, as well as improvements in impedance bandwidth RL and AR. So, in the proposed article two antenna structures ANT-A and ANT-B, are presented. The maximum gain achieved for ANT-A is 34.759dBi, covering the frequency bands (28.997-202.113) GHz, and (205.884-336.693) while in the case of ANT-B, it is 36.3155dBi, covering the frequency bands (29.178-330.490) GHz, and (334.936-336.702) GHz. The proposed antenna structure is a useful design for mm-wave 5G and 6G Sub-THz communications.

Design zigzag edge of S shape slot antenna by using SIW technology for 5G application

Design zigzag edge of S shape slot antenna by using SIW technology for 5G application

On C0 and C1 continuity of envelopes of rotational solids and its application to 5-axis CNC machining

We study the smoothness of envelopes generated by motions of rotational rigid bodies in the context of 5-axis Computer Numerically Controlled (CNC) machining. A moving cutting tool, conceptualized as a rotational solid, forms a surface, called envelope, that delimits a part of 3D space where the tool engages the material block. The smoothness of the resulting envelope depends both on the smoothness of the motion and smoothness of the tool. While the motions of the tool are typically required to be at least C2, the tools are frequently only C0 continuous, which results in discontinuous envelopes. In this work, we classify a family of instantaneous motions that, in spite of only C0 continuous shape of the tool, result in C0 continuous envelopes. We show that such motions are flexible enough to follow a free-form surface, preserving tangential contact between the tool and surface along two points, therefore having applications in shape slot milling or in a semi-finishing stage of 5-axis flank machining. We also show that C1 tools and motions still can generate smooth envelopes.

A 2 shape slot microstrip patch antenna for global positioning system satellite communication applications

In this paper, a compact two-shape slot microstrip antenna is proposed for global positioning system (GPS) satellite application. The proposed antenna is designed with FR 4 substrate with a height of 1.6 mm, a dielectric constant εr of 4.3 within a compact size 56 x 56 mm2 area. The design parameters are optimized to achieve good performance. At the optimum setting of design parameters, this antenna shows good characteristics to cover L1 band 1,575.42 MHz, ± 12 MHz frequency which is used for GPS satellites. At the 1,572 MHz resonance frequency, this antenna achieves a minimum return loss of -30 dB covering a frequency bandwidth of 50 MHz (1,550 MHz – 1,600 MHz) at -10 dB reference level which ensures 100% bandwidth coverage of the L1 band. Besides, the proposed antenna achieved a maximum gain of 8.3 dBi and a beam width of 1010 at -3 dB point. In terms of other performance, such as voltage standing wave ratio (VSWR), directivity, radiation pattern, the proposed antenna shows good performance for the application of GPS satellites.