Parallel Slots Research Articles

A high-selectivity filtering DDPA with raised DDPs and metal vias

ABSTRACT A high-selectivity filtering dense dielectric patch (DDP) antenna (DDPA) with raised DDPs and metal vias is proposed in this paper. The proposed filtering DDPA has three resonant modes, the first two modes are TE 11 mode and the third mode is TE 12 mode. The first TE 11 mode is generated because of the centrally raised small DDP. The second TE 11 mode and the TE 12 mode are the modes of DDP itself. The proposed filtering DDPA has two radiation nulls (RNs). The low-frequency radiation null (LFRN) is generated by loading equal length parallel slots on the ground. DDP itself has a non-radiative high-frequency radiation null (HFRN). By loading symmetrical same metal vias on the DDP, the radiative TE 12 mode and the non-radiative TE 12 mode move to the low-frequency at the same time. That results in a wider passband and excellent high-frequency response. The proposed filtering DDPA is manufactured and measured for verification. The impedance bandwidth is 8.2% from 3.75 GHz to 4.07 GHz. The average gain is 7.7 dBi, and the average roll-off rate is 177 dB/GHz. The measured results prove that the proposed filtering DDPA has good radiation performance and high-selectivity.

Intrusion detection in machine learning based E-shaped structure with algorithms, strategies and applications in wireless sensor networks

In the everyday world of computer applications, from the cloud to the Internet of Things, distributed sensor networks are essential (IoT). These computer application devices are often connected to Arduino network connection and microcontrollers such sensors and actuators. Thus, a defensive network with an IDS serves as the need for contemporary networks. The intrusion detection system has unavoidably evolved throughout the years, but despite this, it remains a difficult study topic since the current intrusion detection system uses signature-based approaches rather than anomaly detection. Therefore, improving the current intrusion detection system is challenging since it is difficult to find zero-day attacks in IoT networks when dealing with varied data sources. Filtered Deep Learning Model for Intrusion Detection with a Data Communication Approach is presented in this study. The five steps that make up the suggested model are Initialization of Sensor Networks, Cluster Formation and Head Selection, Connectivity, Attack Detection, and Data Broker. It was discovered that the suggested model for intrusion detection outperformed both the current Deep Learning Neural Net and Artificial Neural Network. In comparison to the most popular algorithms, experimental findings revealed a superior result of 96.12 % accuracy. The E-shaped patch antenna is a brand-new single-patch wide-band microstrip antenna that is presented in this research. A microstrip antenna's patch has two parallel slots built into it to increase its bandwidth. Investigating the behaviour of the currents on the patch allows for the exploration of the wide-band mechanism. A broad bandwidth is achieved by optimising the slot's length, breadth, and location. Finally, a 40.3 % E-shaped patch antenna is developed, made, and tested to resonate at 7.5 and 8.5 GHz for wireless communications. Additionally displayed are the reflection coefficient, VSWR, radiation pattern and directivity.

A novel structure based on ultra-wideband filtering circuit for isolation enhancement of Vivaldi antenna with narrow gap in H-plane

A novel structure based on ultra-wideband (UWB) filtering circuit for isolation enhancement of Vivaldi antenna with narrow gap in H-plane is proposed in this paper. An antipodal Vivaldi antenna array with series of parallel slots in feed arms and a reflective floor is adopted to gain lower profile height, higher front-to-back ratio (FBR), and better isolation in high frequencies compared to a conventional one. The proposed filtering decoupling structure (FDS), composed of three bow ties with slender serrated lines at the edges distributed on both sides of the dielectric plate, is not only located in the necessary path of the spatial coupling of the two units, but also electrically connected with the reflective floor to enhance the low-frequency decoupling effect. The measured results show that the decoupling antenna array works well in 1.8–12 GHz, and the isolation is improved by 24.1 dB at 3.2 GHz and 12.2 dB at 1.9 GHz with FDS. The proposed FDS works well from 1.6 to 4.7 GHz with bandwidth of 96.7%, and the minimum isolation in the operating frequency band is improved from 10 dB to 19 dB. Moreover, the radiation performance remains superior after decoupling. The proposed decoupling structure is potential in the application in large-scale UWB arrays.

Rayleigh–Bénard convection in mono and hybrid nanoliquids in an inclined slot

Linear stability analysis is conducted to investigate the longitudinal and transverse rolls (TRs) generated in Rayleigh–Bénard convection in mono and hybrid nanoliquids confined between two infinite inclined parallel slots. Thermophysical properties of six mono nanoliquids and fifteen hybrid nanoliquids are calculated for different volume fractions (0.5%, 1%, 2%) using phenomenological laws and mixture theory. The shooting method is used to solve boundary eigenvalue problems to obtain the eigenvalues for 16 different boundary conditions. It is observed that as the inclination angle is increased, it delays the onset of longitudinal rolls in the case of all boundary conditions. However, it advances the onset of TRs except when the lower plate is adiabatic. The addition of mono and hybrid nanoparticles results in the advancement of the onset of convection. The addition of SWCNT and SWCNT— accelerates the onset of convection the most while Cu and Cu-Ag accelerates the onset of convection the least amongst the mono and hybrid nanoparticles considered in the study.

A Novel Self-Actuated Linear Drive for Long-Range-of-Motion Electromechanical Systems

Obtaining powered linear movement over a long range of motion is a common yet challenging task, as the majority of linear actuators have limited ranges of motion as determined by their functioning mechanisms. In this paper, the authors present a novel belt-based self-actuated linear drive (B-SALD), in which a self-powered moving platform slides on a slotted track with essentially unlimited range of motion (only limited by the length of the track). Unlike the traditional rack-and-pinion mechanism, the B-SALD system uses a double-sided timing belt as the power-transmitting element. With the teeth on its inner surface, the belt interacts with a timing pulley for its own circulation; with the teeth on its outer surface, the belt interacts with a linear rail with parallel slots and drives the translation of the moving platform. The unique functioning mechanism generates multiple distinct advantages: no lubrication is required; the slotted track is simple and inexpensive to manufacture; and it provides an inherent compliance to buffer shock loading. With the experiments conducted on a preliminary prototype, it has been demonstrated that the B-SALD is able to provide accurate positioning and continuous motion control, an overall mechanical efficiency of 70% over the majority of the load range, and the capability of generating large force output in the desired manner.

Development of microfluidic chip for entrapping tobacco BY-2 cells.

The tobacco BY-2 cell line has been used widely as a model system in plant cell biology. BY-2 cells are nearly transparent, which facilitates cell imaging using fluorescent markers. As cultured cells are drifted in the medium, therefore, it was difficult to observe them for a long period. Hence, we developed a microfluidic device that traps BY-2 cells and fixes their positions to allow monitoring the physiological activity of cells. The device contains 112 trap zones, with parallel slots connected in series at three levels in the flow channel. BY-2 cells were cultured for 7 days and filtered using a sieve and a cell strainer before use to isolate short cell filaments consisting of only a few cells. The isolated cells were introduced into the flow channel, resulting in entrapment of cell filaments at 25 out of 112 trap zones (22.3%). The cell numbers increased through cell division from 1 to 4 days after trapping with a peak of mitotic index on day 2. Recovery experiments of fluorescent proteins after photobleaching confirmed cell survival and permeability of plasmodesmata. Thus, this microfluidic device and one-dimensional plant cell samples allowed us to observe cell activity in real time under controllable conditions.

A high-gain and low cross-polarized wave-fractal shaped printed antenna for DBS application

This article presents the design of a printed antenna for Direct Broadcast Satellite (DBS) (12.2 – 12.7 GHz) services. The newly designed proposed structure, named as ‘wave-fractal’, is having a considerably high gain and can heavily suppress cross-polarization level along the entire HPBW region. The radiating area of one-quadrant of structure is derived by superimposing six numbers of ‘Golden-ratio’ based squares, and it poses 2D-quadrantal symmetry. In order to resonate the structure at desired frequency, two parallel slots and a circle based defective ground structure is imposed. Furthermore, to achieve a symmetric radiation pattern, a 2D-Octagonal symmetry has been implemented on the proposed structure. The fabricated prototype resonates at 12.49 GHz and gives a gain and x-pol. as 9.52 dBi and −35.36 dB, respectively. The measured impedance bandwidth is 502 MHz, which ensures 100% bandwidth coverage for the DBS band. The measured results make an excellent agreement with its simulated counterpart.

Reduced Cross-Polarization Patch Antenna with Optimized Impedance Matching Using a Complimentary Split Ring Resonator and Slots as Defected Ground Structure

An innovative method is proposed to improve the cross-polarization performance and impedance matching of a microstrip antenna by integrating a complimentary split ring resonator and slots as a defected ground structure. An equivalent circuit model (ECM) enables the design take into consideration the mutual coupling between the antenna patch and the Defected Ground Structure. The input impedance and surface current density analysis confirms that the integration of a CSRR within a rectangular microstrip patch antenna leads to uniform comparative cross-polarization level below 40 dB in the H-plane, over an angular range of ± 50°. Introducing parallel slots, as well, leads to a reduction of spurious antenna radiation, thereby improving the impedance matching. Measurements conducted on a fabricated prototype are consistent with simulation results. The proposed antenna has a peak gain of 4.16 dB at 2.6 GHz resonating frequency, and hence is good candidate for broadband service applications.

Design of Compact D-shaped Frequency Reconfigurable Slot Antenna for Ku/K Band Applications

In this paper, a new compact design of frequency reconfigurable slot antenna is presented. The proposed radiating patch consists of two symmetrical D shape slots and incorporates four PIN diodes with two stubs which cover a small dimension area of 8.6 × 6.0 × 1.6 mm3. The ground plane is modified by etching two parallel rectangular slots to enhance the bandwidth and design parameter of the antenna. RF pin diodes are used as a switching mode in the slotted D section of the patch which affects the electrical length of the slot antenna, therefore switchable frequency response is obtained. The antenna produces four dual-band states and twelve triple-band states among the sixteen states of diode configuration. The designed antenna resonates at six different resonating frequencies such as 17.4 GHz, 17.5 GHz, 18.9 GHz, 19.0 GHz, 24.9 GHz, and 25 GHz and covers the wide range of frequency from 17.2 to 25.5 GHz which makes it applicable to function at the Ku and K band applications. Simulation of an antenna is done by Ansys HFSS 17.0 software. The results of the simulation show that the antenna has achieved a stable radiation pattern with an appreciable gain of 10 dB, peak directivity 4.26 dBi, peak gain 5.66 dBi, and a maximum bandwidth of 1 GHz with 98% radiation efficiency at these operating frequency bands.

Dielectric loaded directive Vivaldi antenna considering dispersion in near and far field

A “V” slot dielectric loaded antipodal Vivaldi antenna is proposed in this article, which provides significant improvement for directivity, front to back lobe ratio and low side lobe level over the operating frequency band from 1.76 GHz to 10 GHz. Initially, the 35° upward tilted parallel slots are placed along the outer curvy conductor edges of the antenna to maintain the desired radiation performances and impedance matching. Thereafter the V slot extended dielectric slab is integrated with this design for the improvement of radiation performances and pulse spreading effect while maintaining high directivity. The antenna prototype is fabricated and tested which shows the return loss is below the 10 dB, maximum directivity is achieved at 10 GHz which is 17.5 dBi and front-to-back lobe level ratio is 29.2 dB, almost triple as compare to conventional Vivaldi antenna at 9 GHz. The measured results depicts that the highest main lobe squint angle is 2.7° at 6 GHz. In addition to this, the measured system fidelity factor (SFF) is 0.86 and 0.91 at near and far field respectively which confirms that the V slot actually reduces the pulse spreading and dispersion effect while maintaining the high directivity.

A 90 GHz SINIS Detector With 2 GHz Readout

A superconductor-insulator-normal metal-insulator-superconductor (SINIS) detector integrated in a planar 90 GHz band twin-slot antenna with a 2 GHz superconducting resonator readout was fabricated and experimentally studied. In order to achieve high pixel count, the traditional dc readout of the SINIS detector is replaced by NbN coplanar 13.850 mm long superconducting resonator. SINIS detectors have traditionally dc Junction Field Effect Transistor (JFET) room-temperature readout. Such readout requires individual wiring for each pixel, while the microwave readout is far less cluttered as only one coaxial line is needed for hundreds of devices. Such readout operates similar to frequency domain multiplexing (FDM) for microwave kinetic inductance detectors (MKID). The planar twin slot antenna has two parallel slots in a metal ground plane which are excited coherently by short sections of a coplanar waveguide (CPW) line with a SINIS detector at the center. One section of the CPW is extended past the slot in a long superconducting section which functions as a quarter wavelength resonator. This resonator is short circuited to the ground plane at the far end, with the expected open circuited end terminated by the SINIS detector in the antenna. We measured the response of sample to black body radiation temperatures 6 K and 9 K. The corresponding dynamic resistance maximum drops from 50 kΩ down to 30 kΩ. An RF readout channel comprising a coplanar coupler and a coplanar resonator has a resonant frequency of 1.8 GHz. Unloaded Q factor (without incoming irradiation) is 200. The signal spectral characteristics and the response to the black body radiation have shown design values as expected.

Design of Dual-Band and Low-Profile SIW Cavity-Backed Slot Antenna for 5G Applications

In this communication, the design of a dual-band and low-profile SIW cavity-backed slot antenna operating at K-band and Ka-band has been proposed to expand the Impedance bandwidth (IBW) of the antenna. The dual-band antenna consists of the SIW cavity with two parallel slots etched on the conductor’s ground plane. To obtain a dual-band, higher-order hybrid modes are tuned and combined to form the second band of the proposed antenna with a broader bandwidth. For dual-band antenna, fractional bandwidth of 5.26% and 6.15% are attained with the maximum gain of 5.45 dBi and 6.15 dBi at 24.7 GHz and 27.8 GHz, respectively. A cavity-backed antenna using via-hole and the slot has been proposed to improve an IBW and other antenna performance parameters. Via-hole establishes a connection between the top and bottom surfaces of the cavity, creating a new path for the current to flow by shortening the slot’s effective length. An IBW of 4.2 GHz (15.32%), where a gain of 7.8 dBi and 9.2 dBi have been realized at 25.9 GHz and 28.8 GHz, respectively. Isolation of less than 25 dB has been achieved through simulation. In terms of λ0, the overall volumetric dimension of the proposed antenna is 1.68 λ0×1.31λ0×0.04λ0. The proposed design demonstrates better performance in terms of antenna parameters, including compactness, good radiation characteristics, enhanced impedance bandwidth, and higher gain than the latest state of the art.

Comparison of slot sizes and parallelism of metal brackets manufactured through metal injection molding and computerized numerical control.

ObjectiveTo investigate and compare the slot sizes and parallelism of metal injection molding (MIM) and computerized numerical control (CNC) brackets.MethodsThe following four MIM bracket series with 0.022-inch (in) slots were selected for investigation Di MIM mini Twin (Ortho Organizers), Mini Diamond Roth (Ormco), Gemini MBT (3M Unitek), and Formula R Roth (Tomy). The following four CNC bracket series with 0.022-in slots were selected for investigation Econoline MBT (Adenta), Legend mini MBT (GC Orthodontics), Crown mini MBT (Adenta), and Evolve MBT (DB Orthodontics). The slot dimensions were measured using an optical microscope (XTCam-D310M; Mitutoyo) with a resolution of 1 μm. The results were statistically analyzed using one-way analysis of variance and the Tukey post-hoc test with a significance level of 0.05.ResultsThe results indicated that all the investigated slot sizes were oversized with respect to the manufacturers’ specifications (0.022 in). Among the eight bracket series, the Di MIM bracket (MIM) was the most oversized by 10.4%, whereas the Evolve bracket (CNC) was the least oversized by 2.6%. The slots in seven of the bracket series had divergent walls instead of parallel ones. The Evolve bracket alone had parallel slot walls.ConclusionsRegardless of the manufacturing method, all the slot sizes of the brackets investigated in this study were significantly oversized; most of the slot walls were nonparallel, except for those of the Evolve bracket. This study could not establish that the CNC method was more accurate than the MIM method in manufacturing bracket slots.

Numerical Investigation on Proppant–Water Mixture Transport in Slot under High Reynolds Number Conditions

Water hydraulic fracturing involves pumping low viscosity fluid and proppant mixture into the artificial fracture under a high pumping rate. In that high Reynolds number conditions (HRNCs, Re > 2000), the turbulence effect is one of the key factors affecting proppant transportation and placement. In this paper, a Eulerian multiphase model was used to simulate the proppant particle transport in a parallel slot under HRNCs. Turbulence effects in high pumping rates and frictional stress among the proppant particles were taken into consideration, and the Johnson-Jackson wall boundary conditions were used to describe the particle-wall interaction. The numerical simulation result was validated with laboratory-scale slot experiment results. The simulation results demonstrate that the pattern of the proppant bank is significantly affected by the vortex near the wellbore, and the whole proppant transport process can be divided into four stages under HRNCs. Furthermore, the proppant placement structure and the equilibrium height of proppant dune under HRNCs are comprehensively discussed by a parametrical study, including injection position, velocity, proppant density, concentration, and diameter. As the injection position changes from the lower one to the top one, the unpropped area near the entrance decrease by 7.1 times, and the equilibrium height for the primary dune increase by 5.3%. As the velocity of the slurry jet increases from 2 m/s to 5 m/s (Re = 2000–5000), the vortex becomes stronger, so the non-propped area near the inlet increase by 5.3 times, and the equilibrium height decrease by 5.2%. The change of proppant properties does not significantly change the vortex; however, the equilibrium height is affected by the high-speed flush. Thus, the conventional equilibrium height prediction correlation is not suitable for the HRNCs. Therefore, a modified bi-power law prediction correlation was proposed based on the simulation data, which can be used to accurately predict the equilibrium height of the proppant bank under HRNCs (mean deviation = 3.8%).

A Wideband Phased Array With Broad Scanning Range and Wide-Angle Impedance Matching

For wide-angle scanning phased arrays, the efficiency of active elements is deteriorated with the increase of mutual impedance. This article demonstrates an effective strategy to control the mutual impedance among array elements by canceling the major coupling effect. The implemented wideangle impedance matching (WAIM) of a wideband phased array verifies the validity of the proposed strategy. For the array element, to obtain wide-angle radiation and wideband characteristic, parallel slots with unequal lengths are deliberately etched on a low-profile substrate integrated cavity (SIC). The mutual impedance between two arbitrary elements is remarkably controlled and compensated by canceling the major coupling effect, which is realized by etching symmetrical slots and loading periodical loops within each element. With the controlled mutual impedance, the proposed array possesses excellent wide-angle scanning performance. Both the simulated and measured results indicate that the designed array steers its main beam from -70° to +70° in the xoz azimuth plane in a broad frequency range from 8.0 to 9.5 GHz. The active S-parameter of each element remains lower than -10 dB in the operating band while the array scans. Due to the implemented WAIM, the total efficiency of the array exceeds 90% during the scan and the fluctuation of realized gain is less than 3 dB.

Design of a substrate‐integrated waveguide based slot‐pair array antenna for bandwidth enhancement

This study proposes a novel radiating element to enhance the bandwidth of a substrate-integrated waveguide-based resonant slot array antenna. Unlike the conventional scheme, the proposed element has two parallel slots of unequal length. The long slot dominates the radiation, while the short one deals with the matching. An amplitude-tapering power divider was integrated into a 5 × 4 element array to restrain the E-plane sidelobe level (SLL). The measured − 10 -dB bandwidth is 23.14–25.4 GHz (9.42% @24 GHz). The E-plane and H-plane SLLs are − 22.04 and − 30.34 dB, respectively. The cross-polarised levels in the operating band are < − 30 dB and a peak gain of 17.77 dBi was measured at 24.2 GHz. A good agreement is observed between the simulated and measured results and then validates the feasibility of the bandwidth-enhanced slot pair proposed herein.

Theoretical investigation of nano-photonic graphene-based waveguide

This paper reports two design thoughts about nano-scale waveguides including parallel slot structure and vertical slot structure. According to the simulation results of different schemes, the design of parallel slot structure is demonstrated to exhibit better performance. Thus, we further explore its typical characteristics based on this scheme, such as electric field distribution, effective refractive index, non-linearity, dispersion and so on. Besides, we explore the properties of the waveguide under different thicknesses of the core material. On the other hand, combining with graphene layer applied to additional bias voltage, the tunable properties of the waveguide are realized. These results can provide significant reference for photoelectronic device field and lead to a deeper insight of the physical mechanisms of graphene-based waveguides.

Disturbance of the Regenerative Effect by Use of Milling Tools Modified with Asymmetric Dynamic Properties

Milling processes are often limited by self-excited vibrations of the tool or workpiece, generated by the regenerative effect, especially when using long cantilevered tools or machining thin-walled workpieces. The regenerative effect arises from a periodic modulation of the uncut chip thickness within the frequencies of the eigenmodes, which results in a critical excitation in the consecutive cuts or tooth engagements. This paper presents a new approach for disturbing the regenerative effect by using milling tools which are modified with asymmetric dynamic properties. A four-fluted milling tool was modified with parallel slots in the tool shank in order to establish asymmetric dynamic characteristics or different eigenfrequencies for consecutive tooth engagements, respectively. Measurements of the frequency response functions at the tool tip showed a decrease in the eigenfrequencies as well as an increase in the dynamic compliance in the direction of the grooves. Milling experiments with a constant width of cut and constantly increasing axial depth of cut indicated a significant increase in the stability limit for the specific preparations of up to 69%.

Ultrawideband Textile Antenna for Wearable Microwave Medical Imaging Applications

This article presents the design of a novel low-profile ultrawideband textile antenna for wearable microwave medical imaging systems. The proposed antenna is based on a monopole structure, where two triangles and a few parallel slots are cut at the bottom corners and top edge of the radiation patch, respectively, to achieve an optimized ultrawide bandwidth and a reduced size of the antenna. Polyester fabrics and conductive copper taffeta, which are universally available on the market, are selected to construct the antenna. Thus, the fabricated prototypes well suit the needs of wearable applications, where flexible components are required to conform to the curved human bodies. The measured results show that the antenna prototype can realize a bandwidth of 109% from 1.198 to 4.055 GHz, with a realized gain of 2.9 dBi. Furthermore, the on-phantom measurements show that there is limited effect on the operating bandwidth and realized gain of the antenna when it is working in the proximity to human bodies. The antenna is used to monitor the recovery process of a bone fracture that is emulated by a body-mimicking phantom with a size-varying blood strip. The time-domain reflection coefficient of the antenna varies significantly with the size of the fracture introduced, which demonstrates the applicability of the antenna for such use scenarios in microwave medical imaging.

Liver-specific 3D sectioning molds for correlating in vivo CT and MRI with tumor histopathology in woodchucks(Marmota monax).

PurposeTo evaluate the spatial registration and correlation of liver and tumor histopathology sections with corresponding in vivo CT and MRI using 3D, liver-specific cutting molds in a woodchuck (Marmota monax) hepatic tumor model.MethodsFive woodchucks chronically infected with woodchuck hepatitis virus following inoculation at birth and with confirmed hepatic tumors were imaged by contrast enhanced CT or MRI. Virtual 3D liver or tumor models were generated by segmentation of in vivo CT or MR imaging. A specimen-specific cavity was created inside a block containing cutting slots aligned with an imaging plane using computer-aided design software, and the final cutting molds were fabricated using a 3D printer. Livers were resected two days after initial imaging, fixed with formalin or left unfixed, inserted into the 3D molds, and cut into parallel pieces by passing a sharp blade through the parallel slots in the mold. Histopathology sections were acquired and their spatial overlap with in vivo image slices was quantified using the Dice similarity coefficient (DSC).ResultsImaging of the woodchucks revealed heterogeneous hepatic tumors of varying size, number, and location. Specimen-specific 3D molds provided accurate co-localization of histopathology of whole livers, liver lobes, and pedunculated tumors with in vivo CT and MR imaging, with or without tissue fixation. Visual inspection of histopathology sections and corresponding in vivo image slices revealed spatial registration of analogous pathologic features. The mean DSC for all specimens was 0.83+/-0.05.ConclusionUse of specimen-specific 3D molds for en bloc liver dissection provided strong spatial overlap and feature correspondence between in vivo image slices and histopathology sections.