Slot Shape Research Articles

Compact textile UWB antenna with hexagonal for biomedical communication

AbstractThis paper introduces a small-sized, low profile, planar and flexible ultra-wide band (UWB) antenna using Jeans, a textile material as the substrate. A novel shape of hexagonal slot in rectangular step shape patch with partial ground plane is developed with bandwidth of 12 GHz is proposed. It is the primary approach in using natural textile as the substrate for UWB antenna which operated in a wide range of bandwidth. The UWB antenna is designed for short range applications including wireless body area network (WBAN), which is the current revolution with growing demands in wireless sensor networks. The antenna operates from 2.8 to 10.9 GHz, which is a suitable candidate for WBAN operation.

Numerical investigation into the effect of geometric shape of slot on air flow field in melt-blown for polymer fiber

In order to obtain smaller diameter melt-blown fiber, we improved the air slot of the melt-blown die in this research and designed the new melt-blown die with the gradually shrinking air slot and arc nose head. Using the numerical simulation method, we analyzed that the new die and the common die affect the velocity field, temperature field, air pressure field, and turbulence strength on the center line. The diameter distribution of the fiber obtained from the die was analyzed by using the one-dimensional tensile model of the melt-blown fiber. The results show that as compared to the common slot shape die, the new die improves the mean velocity along the center line in the fiber main stretch area by 56% and the peak velocity by 38.5%, increases the peak value of the air pressure in the air flow field, reduces the negative velocity in the return flow area, decreases the peak value of the turbulence intensity, and delays the air flow wave nearby the end face of the die, thereby make the fiber motion more smooth. At the same time, the new melt-blown die with the gradually shrinking air slot and arc nose head can make the fibers in the melt-blown process finer and lead to more lower energy consumption for producing the fibers of the same diameter.

Compact four port slot based MIMO antenna with isolation enhancement

ABSTRACT This paper presents the design of a compact arc shape slot antenna and its application in multiple inputs and multiple-output (MIMO) communications. The unit cell antenna has a footprint of 15 × 15 mm2. The antenna with arc shape stub loaded feedline provides broadband impedance matching extending from 3 GHz– 9.5 GHz. The antenna is made dual-polarised using orthogonal feed structure. A four-port, two-element MIMO antenna is constructed by replicating the unit cell design in a parallel fashion. Broadband isolation enhancement is achieved by using a modulated microstrip line embedded with circular patches of varying diameters. The four-port MIMO antenna provides 10 dB additional enhancement in comparison with the unmodulated microstrip line decoupling unit cell. The prototype antenna is fabricated and the simulation results are verified using experimental measurements. The antenna offers an average peak gain of 5.2 dBi and efficiency greater than 75%. The MIMO parameters such as envelope correlation coefficient, diversity gain, mean effective gain are evaluated and presented. The proposed antenna is one of the most compact 4 port solution reported in the literature.

Tri-Band Slot-Loaded Microstrip Antenna for Internet of Things Applications

A new design of a multiband microstrip patch antenna using slots in the patch as well as defected ground structures (DGS) implemented in the ground plane is proposed. Multi resonance response was obtained by etching the DGS shapes in the ground plane of a Traditional patch operates at 5.2 GHz, which is the common frequency for the Internet of Things (IoT) applications. The novel outcome of this work is a compact antenna that resonates at three bands, viz. 2.42, 5.22 and 5.92 GHz. Different shapes of slots were used to improve the antenna performance at the different resonances. The antenna used the inset feeding technique to improve impedance matching. Rogers RO3003 substrate of 3 relative dielectric constant, 0.0013 loss tangent, and 1.5 mm thickness was used to build the antenna. The designed antenna was simulated using HFSS software. The good consistency between simulations and measurements confirmed the antenna's ability to improve the benefits for IoT applications at the three different frequencies.

Employee of the Month as a Motivational Best Practice in Lebanese Hotels

This paper sheds the light on the Best Motivational Practices adopted by HR in the Hotel industry in Lebanon and focuses mainly on the Employee of the month approach as being one of the recent motivational practices in various fields and in the hotel industry as well. This paper scrutinizes the motivational best practices and how they affect the performance of the employee and then moves to the Employee of the month concept while elaborating on its features. Interviews were done from a sample hotel to assess the motivational best practices being applied and introduce the Employee of the month concept as a significant factor to boost motivation. Motivation takes a lot of shapes and has been a crucial topic addressed in many types of research in the business field and it is still being considered a major issue that cannot be ignored despite the increase in the obstacles and difficulties many business industries are facing, but still, employees need to be motivated regardless of the situation and here lies the core focus of this paper.

Investigation of printed slot antennas based on Euclidean geometries

Euclidean and fractal terms are mathematically and physically important terms in antenna design, but rarely reported studies had discussed these terms together in antenna design in their texts. This paper first gives an overview of Euclidean and fractal antennas with useful and satisfactory facts. Four printed slot antennas are then studied using Euclidean slot shapes printed in the ground plane with and without Euclidean patches using FR4 substrate. These antennas are employed to investigate their suitability as simple alternatives to complicated fractal geometries and their specific formulas. Parametric analyses with feedline lengths and patch scaling aspects are adopted to generate single, dual, and multiband responses. These parametric studies provide different outcomes and choices for antenna electrical specifications suitable for various wireless applications. It is clear that inserting Euclidean patches to the printed slot in the ground plane influence inducing multiple operating bands as similar as multiband fractal antenna, but without using specific formulas or complicated outlines. All proposed antennas have low-profile topologies, good compactness, and more competitive electrical specifications than many reported fractal antennas. The simulations of the proposed printed slot antennas are in good compatibility with the measurements.

DESIGN AND ANALYSIS OF ULTRA WIDE BAND ELLIPTICAL SLOT WITH QUARTER WAVE TRANSMISSION LINE GROUND FOR WIRELESS APPLICATIONS

UltraWide Bandwidth (UWB) antenna with Deflected Ground Structure for wireless communication is presented in this paper. Our proposed antenna design is consisting of elliptical shape slot at patch and Quarter wave transmission line at the ground with multiband frequency operation in various wireless communications.An antenna is designed using FR4 substrate with permittivity value of 4.4 and thickness of 0.8 mm. The size of the antenna is 50 x 70 mm2presents a high gain of 4 dB with Ultra Wide Bandwidth. In proposed antenna quarter wave ground is imposed with Deflected Ground Structure to achieve overall size reduction. The ultra bandwidth antenna proposed in this paper operates at multiband frequencies centered at 3.0267 GHz, 6.1933 GHz, 9.1911 GHz, 12.1467 GHz, and 15.06 GHz with corresponding return loss of -24.0553 dB, -40.9292 dB, -20.7534 dB, -41.8718 dB, -30.1747 dB.

Effects of Geometric Dimension Variations on Efficiency of 3-phase Squirrel Cage Induction Motors Considering Economic Evaluation

There are different approaches to improve the efficiency of induction motors. In this paper, the considered approaches include, design of the rotor slot, rotor slot shape, and stator and rotor diameters which are applied on a 30-kW 3-phase, 4-poles, 48-stator slots, and 44-rotor squirrel cage induction motor. Comparison of analytical, simulation and experimental results confirm the proposed FEM-based model of set-up induction motor. The sensitivity analysis of efficiency considering the variations of rotor slot dimensions, stator outer diameter, and stator and rotor diameters have been applied on the case-study. The results of the GA-based optimal design of the rotor slot dimensions showed a 0.32% improvement in motor efficiency. On the other hand, changing the motor core diameters has more effects on motor efficiency so that, when the stator and rotor outer diameters were increased simultaneously, the efficiency was increased by 0.55%. However, if the stator outer diameter just increased, motor efficiency increased by 0.76%. Finally, the economic evaluation was accomplished to validate the optimal approach of motor design for three cases of electricity consumption per kWh.

An Improved Sub-Domain Model of Flux Switching Permanent Magnet Machines Considering Harmonic Analysis and Slot Shape

The flux switching permanent magnet motor is a kind of double-salient machine with good speed regulation performances and application prospects. However, in traditional sub-domain models which are used to exactly calculate the magnetic field of the flux switching permanent magnet motor, the orders of major harmonics can not be intuitively obtained. The computational efficiency and practicality of the sub-domain models are limited. Meanwhile, some errors are caused in the equivalent process of iron slot shapes. Aiming at these problems, an improved sub-domain model is proposed in this paper. The major magnetic field harmonics are selected in advance for each sub-domain region by the magnetic permeance function model of the air gap. In addition, the influence of the slot shape equivalence is corrected by the magnetic permeability of slots, and the accuracy of the sub-domain calculation is improved. The proposed model is verified to have the advantages of high accuracy and fast computing speeds by 2-D finite element analysis. A convenient and reliable approach for flux switching permanent magnet motor designs is provided thereby.

TRANSIENT THERMAL ANALYSIS OF DOUBLE DISK BRAKE ROTOR OF DIFFERENT MATERIALS USING HYBRID MECHANISM

This paper is presented on Design and Thermal analysis of disc brake rotor of different materials, which analyze about on disc brake rotor by analysis of different shapes of slot of different vehicles Disc brake rotor. Therefore, it can optimize number of shapes of slot to estimate the good thermal conductivity of the disc brake rotor. CATIA V5R21 and ANSYS 19R1 software’s are using for Modeling, Static and Transient Thermal Analysis. Heat generated is dissipated faster or the disc material gets less heated. Here is consideration of a metal multiple materials which will satisfy above criteria. An analysis of composite and SS disc brakes over a repeated braking is done and the results are analyzed.

REVIEW OF TRANSIENT THERMAL ANALYSIS OF DOUBLE DISC ROTOR FOR DIFFERENT MATERIALS WITH HYBRID MECHANISM.

This paper is presented review of disc brake rotor of different materials with hybrid mechanism, which is showing about on disc brake rotor by analysis of different shapes of slot of various vehicles. Optimization of shapes and slotsare use to estimate good thermal conductivity of the disc brake rotor. In this paper, review about challenges and problems associated with disk brake and characteristics of Thermal analysis on real model of disc brake rotor. It deals with literature survey of transient, thermal analysis of composite disc brake. Various disk brake as well as its materials is also discussed in this paper for review.

A Comprehensive Disturbing Effect Analysis of Multi-Sectional Rotor Slot Geometry for Induction Machines in Electrical Vehicles

Although the performance of an Induction Motor (IM) can be maximized for any speed by use of an inverter, there is still room to contribute by optimizing the rotor slot shape while decreasing the mechanical disturbing effects and acoustic noise. This paper focuses on the effect of different individual rotor slot shapes on the performance of an IM including overall space harmonic, vibration and acoustic effects. A number of rotor slot shapes were implemented to the rotor of a commercial IM and efficiency of all designs were maximized for constant torque region by optimization. Afterwards, operational performance including starting, breakdown and rated operations; moreover, harmonic content and torque ripple were analyzed numerically in association with the mentioned rotor slot shapes. Best performing 4 rotor slot shapes in terms of chosen operational quantities were designated. Furthermore, the determined motors were carried out to vibration and acoustic noise analysis. Superposed acoustic disturbances in terms of sound power level for different harmonic frequencies were obtained and results are given in comparison. All-in-all, this paper contributes to associating the end-to-end disturbing effects to certain rotor slot shapes. This study determines disturbance and performance criterions for choosing an appropriate motor for an IM to be used in an electric vehicle. It was shown that rotor slot shape still deserves considerable attention to increase the performance of an IM while decreasing the adverse effects of space harmonics, mechanical vibration and acoustic disturbance.

Numerical simulation of the liquid film suction process through the slots of various geometry in the last stages of steam turbines

The liquid film suction process through the slot is considered. The stator blade row of the last stage of the steam turbine was used as an object of study. Based on the CFD modelling of two-phase flow in blades cascade the boundary conditions for slots modelling have been obtained. The numerical analyses of film removal were conducted in a domain including only a flow zone near the studied slot. The multi-phase VOF model was used to calculate the interaction between liquid and steam phases and model the interface evolution during the water removal process. Four different geometries of the slots were considered. For each of them, the unsteady calculations at two different operating regimes have been performed. The numerical results provide information about film suction details in a space of the slot. The behaviour of the film flow was analysed for each slot shape. The conditions of the film separation and its further breakup have been considered. For the studied slot designs efficiency analysis was performed. The results have shown how the way the liquid film moves in the slot effects on the removed water and steam mass flow rates.

Design and Simulation of Triple Band Circular Patch Microstrip Antenna Based on Shape of Ring and Rectangular Slots

In this work, new structures of circular microstrip antenna based on slots are designed and simulated to operate with triple band applications. These slots are annular ring and rectangular shapes in different sizes. The annular ring slot is etched inside the circular patch while the other two rectangular slots are etched on the circular patch edge. The suggested antennas are simulated using version 13 of Ansoft High Frequency Structure Simulator (HFSS). The various parameters such as input impedance, reflection coefficient, gain, radiation patterns and surface currents were investigated. The present results observed that the optimum antenna designed is resonating at three frequencies 2.695, 5.799 and 8.323 GHz. Also, the bandwidths of simulated reflection coefficients at -10 dB are 106, 204 and 371 MHz which are identical with the S-, C- and X-bands frequencies, respectively. Therefore, the optimum antenna designed can be used in the space saving applications in addition to its important role in variety applications at these three frequency bands.

An EH0-Mode Microstrip Leaky-Wave Antenna With Transversal Single Beam via Periodical Loading of Shorting Pins and U-Shaped Slots

This letter presents an improved fundamental EH0-mode microstrip leaky-wave antenna (MLWA) with a transversal single beam by periodically loading a set of shorting pins and U-shaped slots along the longitudinal direction. The original EH0-mode MLWA is constructed by periodically loading a set of shorting pins underneath the microstrip line, but it, unfortunately, radiates symmetric dual beams in the transversal plane. By etching a U-shaped slot in proximity to a shorting pin inside a periodic unit, the adjacent electric field around the shorting pin is interrupted so as to enhance the θ -polarized single beam in the longitudinal plane and weaken the dual symmetric ϕ -polarized dual beams in the transversal plane. An equivalent model is at first established to demonstrate the unique radiation principle of the proposed single-beam MLWA. Next, the effects of the size, shape, and position of a U-shaped slot on the radiation beam are analyzed under fixed pins. In final, a prototype MLWA structure with the improved transversal single-beam radiation performance is designed, fabricated, and measured. The simulated and measured results are found in good agreement with each other, thus validating that the proposed slot-loading technique is indeed useful for the single-beam design of EH0-mode pin-loaded MLWAs.

A Bandwidth-Enhanced Cavity-Backed Slot Array Antenna for mmWave Fixed-Beam Applications

A bandwidth-enhanced $8\times 8$ cavity-backed slot array antenna for fixed beam applications is presented. The antenna consists of four $2\times 2$ subarrays fed by ridge gap waveguide and a modified bow-tie coupling slot in the cavity layer. The proposed bow-tie coupling slot provides additional $\text{10}\%$ impedance bandwidth as compared to the traditional rectangular coupling slot. The fabricated prototype demonstrates an $|S_{11}|\leq -10\,$ dB fractional impedance bandwidth and a $3\,$ dB gain-drop bandwidth of approximately $\text{28}\%$ and $\text{25}\%$ , respectively, with peak gain of $26.4\,$ dBi, aperture efficiency $>\text{60}\%$ and cross-polar discrimination $>40\,$ dB. Measurements show good agreement with simulations. Moreover, we show the impact of the dimensions and shape of the cavity coupling slot on the bandwidth enhancement. The bandwidth enhancement is explained by the double-ridge slot behavior of the bow-tie coupling slot, which shows a more wideband behavior than the traditional rectangular coupling slot behaving like a cross section of a waveguide.

A compactMIMO DRAwith simultaneous frequency and isolation reconfiguration

AbstractThe frequency and an isolation reconfigurable multiple input multiple output (MIMO) dielectric resonator antenna (DRA) is presented in this communication. The design employs a low‐profile rectangular DR element with ground plane having cross shape slots. The slots resonance is effectively combined with the DR‐resonance for size miniaturization. Moreover, the slot responds as defected ground structure (DGS) for the DR element upon placement of PIN diodes. Switching amalgam of diodes results in frequency, isolation reconfigurability and resonates the structure in three distinct configurations covering PCS 1900 MHz, Wimax 2.3 GHz, and LTE 2500‐2700 MHz bands. A thorough parametric study was performed to study the effects of cross shape DGS on the antenna parameters. The prototype of the proposed MIMO antenna is fabricated and results were measured to certify the simulated results. Few parameters of MIMO such like diversity gain (DG), envelope correlation coefficient (ECC), and mean effective gain (MEG) are provided to verify the MIMO performance.

Study on the model of semi-open-end twist in compact spinning with lattice apron

The twist mechanism of the fiber strand in the condensing zone in compact spinning is complex. This paper proposes a dynamic model to evaluate the additional twist of the fiber strands. Based on the flow simulation in the condensing zone, the fiber trajectory in the suction slot was simulated and obtained. Several spinning parameters such as suction slot angle, suction slot width, negative pressure, and shape of suction slot, were varied to show their effects on the additional twist. The simulation results indicated that by increasing the suction slot angle from 5° to 10° the additional twist increased significantly. Higher negative pressure also leads to an increase in the additional twist. The suction slot width has a greater effect on the fiber trajectory than on the additional twist. An arc-shape suction slot increased the additional twist compared with a linear-shape one. An experimental test conducted revealed a precise agreement with the simulation results.

Experimental investigation on the effect of different slot shapes and configurations on scour dimension downstream of flip buckets

Flip buckets at the end of a spillway can dissipate the flood discharge energy. Compared to other energy dissipators, this is a cost-effective structure. The formation of a scour hole downstream of a flip bucket is a topic of interest among hydraulic engineers. The current study investigated scouring downstream of a flip bucket under two major scenarios: (i) free conditions, and (ii) slotted conditions with rectangular and triangular slots configured differently under four different discharge rates. In total, 20 experiments were conducted in this study. Results showed that the use of a deflector slot greatly affected the scour extent and depth, resulting in a greater scour reduction (53%) in the labyrinth rectangular slotted bucket compared to the solid bucket. The results were compared to empirical equations, and a high correlation was observed between them. In comparison, the Taraimovich equation produced more accurate results in control experiments, and the Damle-A and Damle-B equations produced more accurate results in experiments corresponding to labyrinth rectangular and triangular slotted buckets.

Optimal Design of Line-Start Permanent Magnet Synchronous Motor Based on Magnetic Equivalent Parameters

This paper used a lumped magnetic parametric approach-based analytical technique to design the 7.5 kW, three-phase line start permanent magnet (LSPM) motor. In order to enhance the efficiency and power factor (PF) of the prototype LSPM machine, an optimized slot shape of rotor permanent magnet (PM) was selected. The lumped magnetic circuit model is developed to present the magnetic characteristics, and analytical expressions are derived under the open circuit condition. The impact of the design variables on the analytical model air gap flux density distribution and magnetic flux leakage is studied for the LSPM. The design variables have a significant influence on the steady-state performance characteristics of the LSPM motor. Therefore, to verify the output results of the purposed model, the two-dimensional finite element analysis (FEA) was evaluated for the numerical solution of the analytical model.