Slot Pattern Research Articles

Retrospective Flash Glucose Monitoring Analysis in Patients with Type 2 DM, Closer to Target

Undiagnosed or poorly managed diabetes may be associated with several complications including cardiac ailments, lower limb amputations, blindness or renal disease. Projections state that India would lead this increasing public health concern with a staggering incidence of 134.3 million patients by the year, 2045 based on current trends. We utilized the FreeStyleLibre Pro Flash Glucose Monitoring (FGM) system, a novel automated ambulatory glucose profile (AGP) reporting system to identify precise hyperglycemic spikes in a specific patient population. There were 53 T2DM patients with an AGP-estimated HbA1c close to target levels (HbA1c between 7-8%). The 24-hour glycemic patterns were divided into 2-hour time slot patterns for review and analyses; thus, identifying precise spikes contributing to hyperglycemia in patients not achieving their target HbA1c. The highest glycemic peaks were observed between 10 am to 12noonand between 10 pm-12 am [mean interstitial glucose (mg/dL) ± SD of 204 ± 36 and 186 ± 23] coinciding with the post-breakfast and post-dinner periods, respectively. As shown in Table 1, the variation in glycemic spikes ofeach of the 2-hour slots was statistically significant (p<0.0001). FGM helped us identify glycemic variability and specifically, the contribution of post-breakfast hyperglycemia in precluding patients from achieving their target metabolic goals. Disclosure M.S. Chawla: Speaker's Bureau; Self; IPCA Laboratories, Eli Lilly and Company, Novo Nordisk A/S, MSD Pharmaceutical Pvt. Ltd., Boehringer Ingelheim Pharmaceuticals, Inc., AstraZeneca. Speaker's Bureau; Spouse/Partner; Sanofi. P.M. Chawla: Speaker's Bureau; Self; Sanofi. Speaker's Bureau; Spouse/Partner; Eli Lilly and Company, IPCA LABORATORIES, Novo Nordisk A/S, MSD PHARMACEUTICALS PVT. LTD., Boehringer Ingelheim Pharmaceuticals, Inc., AstraZeneca. M.C. Kothari: None. A.F. Shaikh: None. N. Wadhwa: None.

A novel anatomical thin titanium mesh plate with patient-matched bending technique for orbital floor reconstruction

This study developed an anatomical thin titanium mesh (ATTM) plate for Asian orbital floor fracture based on the medical image database. The computer aided stamping analysis was performed on four hole/slot patterns included the control type without hole design, circular hole pattern, slot pattern and hole/slot hybrid patterns within the ATTM plate with upper/lower dies of averaged orbital cavity reconstruction models. The curved-fan ATTM plate with 0.4 mm thickness was manufactured and pre-bent using a patient matched stamping process to verify its feasibility and the interfacial fitness between the plate and bone on the orbital floor fracture model. The stamping analysis found that the hole/slot hybrid patterns design resulted in the most favorable performance among all designs owing to the lowest maximum von-Mises stress/strain and spring-back value. The interfacial adaption results test showed that the average patient-matched stamping bending gap size was only 0.821 mm and the operative time was about 8 s. This study concluded that the curved-fan ATTM plate with hole/slot hybrid pattern design and patient-matched pre-bent technique can fit the ATTM plate/orbital cavity interface well, decrease unstable fracture segment mobility and improve the overall reduction efficiency.

Numerical Study for Brake Squeal by Machining Patterns on Frictional Surface

Automotive brake noise has become a stubborn problem as automotive cars achieve higher driving torques, since that the increased torque induces the generation of severe noise dissipation during brake operation. Moreover, the global brake tuning market for achieving higher performance of the vehicle has expanded recently. The need to control the noise grows more in this connection. The tuning brake kits have employed cross-drilled and slotted machining pattern on the surface of the rotor. These designs have advantages to improve air ventilation, temperature control, and surface cleaning of brake pad. However, the effects of modal frequency by patterned rotor surfaces are rarely discussed, even if it is highly related with brake squeal phenomenon. Therefore, this study deals with the relationship between patterned surfaces and brake squeal through the numerical methods. The commercial software of a finite element analysis is employed for calculation by varying geometric design factors of each rotor pattern. As a result, the cross-drilled machining patterns are concluded to be an influential factor for in-plane mode frequency while the slotted patterns have more leverage for out-of-plane mode frequency.

Power allocation for wireless powered MIMO transmissions with non-linear RF energy conversion models

We study a radio frequency (RF) wireless energy transfer (WET) enabled multiple input multiple output (MIMO) system. A time slotted transmission pattern is considered. Each slot can be divided into two phases, downlink (DL) WET and uplink (UL) wireless information transmission (WIT). Since energy conversion efficiency of the energy harvesting circuits are non-linear, the conventional linear model leads to a mismatch for resource allocation. In this paper, the power allocation algorithm considering the practical non-linear energy harvesting circuits is studied. The optimization problem is formulated to maximize the energy efficiency of system with multiple constraints, i.e., the transmission power, the received power and the minimum harvested energy, which is a non-convex problem. We transform the objective function from fractional form into an equivalent objective function in subtractive form and provide an iterative power allocation algorithm to achieve the optimal solution. Numerical results show that our proposed algorithm with the non-linear RF energy conversion models can achieve much better performance than the algorithm with the conventional linear model.

Scattering of Electric Field from Leaky Coaxial Cable in Confined Area

The new radiation model for the electric field scattering of single leaky coaxial cable (LCX) being a transmitting antenna in the rectangular blind zone at 1.8 GHz is reported. The effect of varying the receiving antenna distance from the LCX on the fluctuation of radiated field using Ray-Tracing Method is examined. The line of sight and reflected paths between the LCX and receiving antenna for both horizontal and vertical polarizations are considered. Furthermore, it is inferred that the selection of appropriate period of slots and distance of the receiver reduce the fluctuations of electric field. The theory and procedures used in this paper can be extrapolated in different slot patterns of the LCX and zones which have many valuable applications for mobile communication in underground mines, tunnels, and railways.

Ultra‐wideband reconfigurable radiation pattern antenna for diversity applications

A radiation pattern reconfigurable planar antenna operating at an ultra-wideband frequency range of 2.78–10.85 GHz is proposed. The proposed antenna is a combined structure of a monopole and a tapered slot, and it has two types of radiation patterns that can be chosen to be a monopole pattern or tapered slot pattern by controlling the states of four diodes. In addition, the shape of both radiation patterns is maintained across the whole operating frequency range. Details of the operation principle and the design considerations of the proposed antenna are presented.

Feasibility study of a double-step hydroforming process for fabrication of fuel cell bipolar plates with slotted interdigitated serpentine flow field

Bipolar plate is considered as one of the main components of a fuel cell which has high weight and cost in the manufacturing of fuel cells. These plates are manufactured by different processes such as stamping, rubber pad forming, electromagnetic forming, and hydroforming, each of which has its own specific limitations. Among these processes, hydroforming is considered as a practical method in forming bipolar plates with complicated pattern due to its significant advantages. Bipolar plates have different flow field patterns including parallel, pin type, interdigitated, and serpentine patterns. Forming of slotted interdigitated serpentine flow field is very difficult due to its high geometrical complexity and accuracy of the flow pattern, small distance between slots, and very low thickness of sheet. To overcome this problem, a double-step hydroforming process is proposed in this work: an initial hydroforming step on a concave die and a final hydroforming step on a convex die. It is shown that the double-step hydroforming process is a feasible technique for fabricating metallic bipolar plate of proton exchange membrane (PEM) fuel cells with thin slotted interdigitated serpentine pattern.

IJIREEICE - Electrical, Electronics, Instrumentation and Control

A circular ring slot antenna (CRSA) with microstrip feeding technique is analysed at 2.45 GHz frequency. In order to suppress additional harmonics produced by the ring slot pattern in wide range nearly 3 to 8 GHz, a defected ground structure (DGS) is integrated into the CSRA. The proposed antenna is analysed and simulated mainly for the wireless sensor network applications. This antenna is simulated by the High Frequency Structure Simulator (HFSS). Analysing the proposed antenna and simulated results on return loss, radiation pattern and gain.

Simulation for slot pattern variation of rotary disk of the variable radius pulley

Simulation for slot pattern variation of rotary disk of the variable radius pulley

Dual optimization method of radiofrequency and quasistatic field simulations for reduction of eddy currents generated on 7T radiofrequency coil shielding.

To optimize the design of radiofrequency (RF) shielding of transmit coils at 7T and reduce eddy currents generated on the RF shielding when imaging with rapid gradient waveforms. One set of a four-element, 2 × 2 Tic-Tac-Toe head coil structure was selected and constructed to study eddy currents on the RF coil shielding. The generated eddy currents were quantitatively studied in the time and frequency domains. The RF characteristics were studied using the finite difference time domain method. Five different kinds of RF shielding were tested on a 7T MRI scanner with phantoms and in vivo human subjects. The eddy current simulation method was verified by the measurement results. Eddy currents induced by solid/intact and simple-structured slotted RF shielding significantly distorted the gradient fields. Echo-planar images, B1+ maps, and S matrix measurements verified that the proposed slot pattern suppressed the eddy currents while maintaining the RF characteristics of the transmit coil. The presented dual-optimization method could be used to design RF shielding and reduce the gradient field-induced eddy currents while maintaining the RF characteristics of the transmit coil.

Microstrip-Fed Printed Slot Antennas Based on Hilbert-Type Space-Filling Curves for Wireless Communication Systems

In this paper, two microstrip-fed printed slot antennas have been introduced to be used in modern communication systems, as alternatives for conventional Hilbert slot antenna. The slot structures of the proposed antennas are in the form of the 3rd iteration of two variants of the conventional Hilbert space-filling curves. These antennas are fed with 50 Ω microstrip line printed on the reverse side of the slot structure. The proposed antennas have been modelled and analyzed using the method of moments (MoM) based commercially available software, IE3D from Zeland Software Inc,. Simulation results show that all these antennas possess a multi-resonant behavior with a miniature size of about half the guided wavelength. It has been found that the fundamental resonance depends on the external side length of the slot structure, while higher mode resonances are attributed by the smaller self-similar structures the slot pattern contains. Furthermore, amongst the proposed antennas, the antenna with slot structure based on Moore’s space-filling curve, which is a closed version of Hilbert curve, has been found to offer a multiband behavior with enhanced bandwidths around the multiple resonances as compared with the other two antennas based on other Hilbert space-filling variants.

Frictional slip lengths for unidirectional superhydrophobic grooved surfaces

The exact solutions due to Philip [ZAMP 23, 353 (1972)] for Stokes shear flow over a periodic array of no-shear slots embedded in a no-slip surface are generalized to account for an arbitrary pattern of no-shear slots in each period window. The slots, or grooves, in each period window run parallel to each other, and are of infinite length, but their widths and separations can be specified arbitrarily. Explicit solutions are found both for longitudinal and transverse flows over the composite grooved surface. Analytical expressions for the transverse and longitudinal slip lengths associated with the microstructured surfaces are then found as functions of the geometrical parameters characterizing the surface. The formulae are relevant to a wide class of flow geometries and are expected to provide a useful tool in the design, analysis, and optimization of the friction properties of grooved microstructured superhydrophobic surfaces. The results are used to show that introducing even a very small wetted region in a no-shear slot can have a significant influence on the effective slip length.

Accuracy of 2-Dimensional Object Location Estimation Using Leaky Coaxial Cables

The improvement of position estimation accuracy is a very important factor in various radar applications. This paper focuses on two-dimensional (2-D) location estimation in radar surveillance using leaky coaxial cables. A leaky coaxial cable is a kind of antenna and has recently attracted attention as a powerful tool for vehicle detection and as an intrusion detection sensor for perimeter security. We derive the Cramér-Rao bound (CRB) for a leaky coaxial cable sensing application and introduce the CRB ellipsoid to evaluate the accuracy of the 2-D location estimation of an object. The diameter and angle of a CRB ellipsoid indicates its error distribution. A leaky coaxial cable has an outer conductor with periodic slots. Its slot pattern determines the radiation characteristics such as the beam angle and harmonic radiation. We focus on the slot pattern to improve the estimation accuracy. Numerical analyses show that a slot pattern generating multi-beams improves the accuracy while single radiation is preferred for general use in communication applications.

Mutual coupling suppression in closely spaced antennas

A technique to significantly reduce the mutual coupling between closely spaced antennas operating at the same frequency band is presented. The method comprises the use of two ground-plane side walls that are erected vertically next to adjacent antennas. The side walls are defected with a lattice pattern of slots to form a defected wall structure (DWS). In addition, the adjacent antennas sharing a common ground plane are separated with a pair of slits in the ground plane. This technique implemented on closely packed antenna suppresses surface waves in the antenna's operation band and can provide isolation of 56 dB, which was achieved with a DWS loaded with mushroom-shape slots separating two microstrip patch antennas. In this case, the inter-antenna spacing (centre to centre) is 0.272λo and ground-plane size is 0.606×0.370λo2. Also investigated is the number of DWS slot loadings on isolation between adjacent antennas. Furthermore, the proposed technique is shown to substantially reduce mutual coupling between planar inverted-F antennas (PIFAs) and monopoles. The measured results validate the proposed technique and vindicate the simulation results.

K-band power divider with metal bridge structures for size reduction using CMOS technology

A K-band power divider with metal bridge structures, which is based on the Wilkinson type is proposed using a standard 0.18 μm CMOS process. The metal bridge structures are applied to the power divider to achieve small size. Additionally, slow-wave structures such as meandered line and slot pattern ground are used for small chip size and high performance. The proposed power divider shows an improved slow-wave factor of 8.2% compared with a power divider with the conventional meandered line structure. The proposed power divider presents a size of 306 × 296 μm and wide bandwidth of 58% for isolation <15 dB. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:379–381, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25691

Performance of Microstrip Low-Pass Filter on Electromagnetic Band Gap Ground Plane

In this work, the performance characteristics of a printed low-pass Alter (LPF) were analyzed on an electromagnetic band gap (EBG) ground plane. A ninth order Chebyshev LPF was designed at 2.44 GHz cut-off frequency using Stepped Impedance Resonator (SIR) method. The simulation results show that the EBG pattern of rectangular slots etched on the ground plane and located offset from the center line not only offers an improved stopband characteristic but also reduces the overall size of the Alter. Finally, a prototype model was developed based on the results obtained from the simulation and tested. The simulated and experimental results show good agreement.

A NEW MINIATURIZED FRACTAL FREQUENCY SELECTIVE SURFACE WITH EXCELLENT ANGULAR STABILITY

A new miniaturized bandpass fractal frequency selective surface (FSS) with excellent angular stability performance is proposed. The miniaturization has been achieved by scheming out a symmetric fractal pattern of continuous slots from the surface of a square-shaped patch, in which each periodic cell consists of incurved slot resonator for reducing the cell size. Reduction in FSS size of up to 74% with respect to the conventional square loop aperture FSS operating at the same frequency of 3.3GHz is obtained. Furthermore, results show excellent angular stability for both vertical and horizontal polarization at difierent incidence angles because of its fractal conflguration. A prototype is fabricated, and the FSS measurement and simulation results are presented and discussed.

Supersonic aerodynamics of a projectile with slot cavities

AbstractThis paper presents the results of experimental and computational investigations on the effect of slot cavities on a supersonic projectile. Experimental work was carried out to show the effects of the slots on the drag at Mach numbers M = 1·36, 1·65, 1·83. The computational analysis was done at M = 1·36. A single configuration of the slot pattern was used with two different slot widths (0·5mm and 2·0mm). Flow features were investigated in the slotted area and at the base. The analysis presented includes the pressure distribution, the supersonic cavity flow and the effect of the slots on the overall aerodynamic drag. Unlike the case of slots at transonic speeds, the suction and blowing mechanism is not found at supersonic Mach numbers. Streamwise cavity slots cause a small base drag reduction. The reduction in total drag is modest when the width is 0·5mm. However, the experiments showed that with the wider slots (2mm) the drag actually increases at Mach numbers from 1·36 to 1·83.

Planar Substrate Integrated Waveguide Cavity-Backed Antenna

A new cavity-backed antenna compatible with planar technology is designed, manufactured, and measured. The original design consists of a slotted cavity fed by a microstrip line. This allows the implementation of the feeding line and the cavity on a single substrate, compatible with a standard printed circuit board (PCB) or low-temperature cofired ceramic (LTCC) process. The idea is to combine specific slot patterns on the cavity back face such as meandered and edge slots. An example is presented, and the measurements show minimum 10-dB return loss bandwidth of 1.32%, 8.5 dBi gain, and 21 dB front-to-back ratio. The combination of volume cavity, planar feeding, and antenna layout, leads to light weight, easy fabrication, and easy integration with planar circuits.

Bandwidth enhancement of K‐band CMOS mixer using balun matching for UWB radar

AbstractA K‐band double balanced mixer with 1.9 GHz ultra‐wide bandwidth in a 0.18 μm CMOS technology is presented in this article. Baluns with slot pattern ground were applied to the proposed mixer for an ultra‐wide band matching in RF and LO ports. The mixer down converts RF signals (23.1–25 GHz) to intermediate frequency signals (100 MHz–1 GHz) using a LO signal of 24.1 GHz. The mixer achieves a conversion gain of 3.4 dB with a RF signal of 24 GHz and a LO signal of 24.1 GHz. A 1 dB compression point of the mixer is −4 dBm, and the mixer consumes 20 mA current with a 1.8 V supply. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 232–235, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23991