Rectangular Plane Research Articles

InSAR-derived present-day crustal movement of Daliangshan on the southeastern margin of the Qinghai–Tibetan Plateau

SUMMARY The Daliangshan area of Sichuan, China, is located on the southeastern margin of the Qinghai–Tibetan Plateau. It marks the central section of the left-lateral Xianshuihe–Xiaojiang Fault System (XXFS), which plays a crucial role in accommodating clockwise vertical-axis rotation of the expanding Qinghai–Tibetan Plateau relative to the South China Block. The area is seismically and tectonically active, and three major active faults—the Anninghe fault (ANHF), Zemuhe fault (ZMHF) and Daliangshan fault (DLSF)—together accommodate a significant amount of left-lateral strike-slip motion. Here, we present a geodetic study of the Daliangshan area mainly based on satellite interferometric synthetic aperture radar (InSAR). We processed Advanced Land Observing Satellite-2 (ALOS2) Phased-Array L-band Synthetic Aperture Radar-2 (PALSAR2) imagery to reconstruct the present-day interseismic deformation field. We developed an optimal atmospherics phase correction strategy to overcome the significant artefacts caused by ionospheric and tropospheric. By applying a multitemporal analysis on corrected interferograms, for the first time we generated a spatially continuous deformation rate field for the Daliangshan area. The satellite line-of-sight (LOS) rate field agrees with Global Positioning System (GPS) and levelling data to ∼2 mm yr–1, confirming that our processing approach is suitable for use in heavily vegetated areas. The InSAR rate map reveals displacements along the central and southern segments of the DLSF and ZMHF. By applying an inversion based on the Okada model, we quantitatively estimated the kinematic parameters of fault segments. Assuming a simple rectangular fault plane for each fault segment and constrained with the prior knowledge of the left-lateral slip, we determined that the ZMHF has a slip rate of 5.06$\pm 0.99{\rm{\ mm}}\,{\rm{yr}}^{-1}$ with a rake angle of ∼$38^\circ $ gently dipping to the SW. The southern section of the DLSF has a rake of $- 48^\circ \,\,{\rm to}\,\, - 41^\circ $ with the total slip rate of $4.93 \pm 0.4{\rm{\ mm}}\,{\rm{yr}}^{-1}$, dipping towards to the NE at $63.50^\circ \pm 2.31^\circ $. The modelled 3-D rate field has been validated with GPS and levelling measurements. Additionally, the inversion model and strain field suggest that the middle section of the DLSF undergoes strong deformation. We considered the implications of three factors—oblique convergence, gravity-driven movement, and the ELIP beneath the Sichuan–Yunnan area—for complex 3-D velocities in the transitional Daliangshan area.

Modeling returned signal of a satellite laser altimeter over an urban area.

Modeling the returned signal of a satellite laser altimeter is a significant theoretical foundation for understanding the topography of the Earth. According to the lidar equation and working principle of laser altimeter, we establish the mathematical expression of the urban target response waveform (TRW) by using a definite integral formation. The characteristic parameters of the TRW, including signal energy, time delay, pulse width, and skewness are deduced in detail. Based on the specifications of the global ecosystem dynamics investigation laser altimeter and the assumption that the target is considered a rectangular plane, we simulate the influences of the geometrical parameters of the target, including the region area, the center geolocation, and the surface slope, on the TRW patterns and the characteristic parameters. The simulation results show that the TRW would present left-skewed and right-skewed patterns, with the exception that the center geolocation is nearly coincident with the laser footprint center. Such skewed distributions make the time delay derived from the TRW time centroid inaccurate for representing the range between the laser altimeter and the target center. In addition, the TRW energy is positively proportional to the region area and the proximity of the center geolocation to the laser footprint center and attenuated by the cosine of the surface slope. The root-mean-square pulse width is principally determined by the tangent of the surface slope. The simulation results contribute to a better understanding of the relationship between the TRW pattern and the geometrical parameters of the illuminated target. In particular, the characteristic parameters of the TRW can provide the detailed references for developing the waveform processing algorithm and the inversion of the surface elevation, the slope, and the reflectance. The returned signal in this paper may facilitate the application of the satellite laser altimeter over an urban area.

Mathematical treatment of looped storage-discharge relation

ABSTRACT In hydraulic and hydrologic modeling, the storage (S)-discharge (Q) relation is often represented by a straight line or a curve, although when plotted using field or experimental data it is found to be hysteretic or looped. The characteristics of this looped relation depend on geometric, hydrologic, and hydraulic conditions. Despite the widespread use of the storage-discharge relation, there does not appear to have been a mathematical treatment discussing what causes the relation to be looped or double-valued. The objective of this study, therefore, is to analyze the S-Q relation analytically for a catchment represented by a rectangular plane, considering rainfall excess (rainfall minus infiltration) and surface runoff or overland flow modeled by kinematic wave approximation. Depending on the duration of rainfall excess, two cases - equilibrium and partial equilibrium - are distinguished and for each case the looped relation is analyzed. It is shown that the loop is different for the two cases.

Layout and optimization of LED light source for indoor visible light communication

AbstractThis paper proposes a novel polygonal layout based on rectangular plane stereo space. The illumination and signal‐to‐noise ratio of polygonal layout and circular layout is simulated in a 5 m × 4 m × 3 m room; The simulation results show that: compared with the illuminance uniformity of the circular layout of 0.67, the illuminance uniformity of the polygonal layout reaches 0.81, which is improved by 20.90%. The position and power of the polygonal layout are further optimized respectively by particle swarm optimization (PSO), and the illuminance uniformity and signal‐to‐noise ratio quality factors (Q) of the polygonal layout can be increased from 0.81 and 19.31 to 0.88 and 37.38 after optimization, respectively. The illuminance uniformity increased by 8.64%, and the Q increased by 93.58%. The experimental system of polygonal layout optimized by PSO is built, by comparing the simulation and experimental results, the average illuminance error of the simulation and experiment is 10.58%, the illuminance uniformity error is 5.68%, and the illuminance distribution trend is consistent.

Metasurface-Loaded Off-Center Monopoles With Wideband Radiation Performance Using Characteristic Mode Analysis

A metasurface (MTS)-based reactive impedance surface (RIS) is proposed to load an eccentrically placed monopole above a ground plane for controllable wideband omnidirectional radiation. With the off-center placement, the radiation pattern of the monopole is not omnidirectional anymore, with ripples in the H-plane measured by un-roundness. The RIS is introduced above and in parallel with the finite ground plane and the monopole is placed in the center of the RIS. Characteristic mode analysis (CMA) is used to analyze the RIS-loaded monopole and to reveal the mechanism. It is found that two desired modes determine the bandwidth of the omnidirectional radiation together. The resonant frequency of the RIS mode can be easily tuned by changing the sheet impedance of the RIS. A metal-dielectric-metal constructed MTS is proposed to realize the RIS. The grid impedance of the MTS can be tuned easily by changing the size of the patch in the unit cell. For a single monopole placed off-center above a rectangular ground plane (150 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times300$ </tex-math></inline-formula> mm), the impedance bandwidth is increased from 19.6% to 32.4% with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert &lt; -10$ </tex-math></inline-formula> dB at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{0} =2.5$ </tex-math></inline-formula> GHz. And the maximum un-roundness is reduced by 66.7% from 4.8 to 1.6 dB over the frequency band of 2.2–2.8 GHz. For a two-monopole antenna system with the same ground plane mentioned above, the loading MTS increases the impedance bandwidth of the monopole from 19.2% to 32.4% with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert &lt; -10$ </tex-math></inline-formula> dB at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{0} =2.5$ </tex-math></inline-formula> GHz. When only one monopole is loaded with MTS in the system, the maximum un-roundness is reduced by 65.5% from 5.5 to 1.9 dB in the frequency band of 2.2–2.8 GHz. When both monopoles are loaded with MTS in the system, the maximum un-roundness is reduced by 40% from 5.5 to 3.3 dB in the frequency band of 2.2–2.8 GHz. The antenna prototypes are fabricated and measured.

Design of pattern-reconfigurable circularly polarized unidirectional antenna based on quasi-radiator for ISM applications

A pattern-reconfigurable circularly polarized antenna for 2.45 GHz industrial, scientific, and medical (ISM) band applications is designed in this work. The proposed antenna consists of a slotted-stepped monopole connected to a rectangular ground plane via a shorting side-stub. This converts the omnidirectional radiation pattern of the antenna into stable unidirectional radiation. To dynamically steer the realized pattern, two switchable RF PIN diodes are jointly incorporated into the side-stubs to achieve symmetrical radiations in specific operating modes. In this way, the radiation patterns can be simultaneously tuned in the ±y directions by the simple switching of the PIN diodes ON and OFF. The fabricated prototype achieves an S11 smaller than -10dB within the 3dB axial ratio (AR) bandwidth with stable far-field patterns. The antenna maintains a low-profile and compact size of 0.055λ02 which makes it suitable for body-centric wireless communication (BWC) and personal wireless area networks.

Construction and dynamic identification of aeroelastic test models for flexible roofs

The aeroelastic wind tunnel testing of flexible roofs made of hyperbolic paraboloid cable nets is a challenging task for designers and researchers, with very limited documented experiences in the literature. The reduced-scale model construction and its dynamic identification are the main issues to address when approaching this problem, mainly because of (i) the very small mass of the roof, (ii) the strict aeroelastic criteria to satisfy and (iii) a large number of very closely spaced significant natural frequencies. To suggest an approach to follow to investigate the wind—structure interaction for this structural typology, this paper discusses the aeroelastic scaling, the aeroelastic model construction, the dynamic modal identification and the FEM predictive numerical modelling of hyperbolic paraboloid roofs (HPRs) with square, rectangular and circular plan shapes and two different curvatures. Modal identification is especially challenging due to the presence of several closely spaced modes and it is here tackled by different methods such as Welch’s method, random decrement technique (RDT), Empirical mode decomposition with a time-varying filter (TVF-EMD) and frequency domain decomposition method (FDD). The satisfying accuracy of the aeroelastic scaling has been verified by comparing the wind-induced vertical displacements of the prototypes against those of the experimental models. Furthermore, an extensive qualitative investigation of the natural mode shapes has been carried out revealing that test models reproduce most of the prototype modes.

Climate adaptation of design scheme for energy-conserving high-rise buildings—Comparative study of achieving building sustainability in different climate scenarios

Given the climate-sensitive interactions between buildings and the immediate environment, an insight into the impact of design parameters on building energy performance under specific climate environments is crucial for the sustainable development of green buildings. The following study imparts a distinctive view of the performance-based effect of architectural and engineering design parameters on high-rise office buildings by exploiting the advantages of climatic features in different climate environments. Therewith, the study identifies and compares the major sensitive design parameters on the energy performance of high-rise buildings in different climate contexts. Furthermore, the most applicable passive strategies to attaining stipulated building sustainability criteria are established. The results indicate that the energy performance in a certain climate environment is highly sensitive to the design characteristics, such as plan ratio, core position and atrium effect. In a cold climate environment, a high-rise building with a rectangular building plan (plan ratio = 1:1.44, with vertical split-core in the absence of an atrium), satisfies the Passivhaus engineering criteria on air-tightness and fabric insulation; and adopts double-glass curtain walls, presented the best energy performance. Whereas, a square building plan (with vertical split-core and no atrium) that complies with the air-tightness and fabric insulation criteria under Passivhaus engineering standards, minimizes east- and west-bound window exposures, and adopts double-glass curtain walls exhibited the best energy performance in the hot climate zone. However, it requires renewable energy systems as an additional energy source to attain the stipulated building sustainability criteria.

An Assessment of the Relation between Architectural and Structural Systems in the Design of Tall Buildings in Turkey

Many professionals from several disciplines need to cooperate in designing and constructing tall buildings since their design and construction require more complex systems and technologies in terms of structure, installation, facade, vertical circulation and fire systems compared to low-rise buildings. The architects who design tall buildings have to know the architectural and structural design considerations of tall buildings and their interrelations well. This study is expected to reveal the status of tall buildings completed in Turkey and help designers understand architectural forms, floor plans, core planning and structural systems of tall buildings. For this purpose, the factors affecting architectural and structural design were examined, and the relation between the architectural–structural system was revealed for tall buildings completed in Turkey. In order to study architectural and structural considerations, 230 constructed tall buildings in Turkey were selected and analyzed in detail. According to the results of the study, it is seen that the prismatic form is widely used as the building tower form in Turkey, the shear-frame system as the structural system, the residential function as the building function, the single symmetrical central core as the building core, and the rectangular plan as the building floor plan alike.

COMPUTATION OF QUASISTATIC ELECTROMAGNETIC FIELDS OF COMPLEX ELECTRIC POWER FACILITIES

: Accurate computation of low-frequency quasistatic electromagnetic fields is important in the design of electricity transmission and conversion devices. This work presents the theoretical groundwork of a computation using integral equations. The procedures for solving these equations are defined by applying the method of moments and the point matching method. The unknown distribution of the source function density on the thin-wire elements is approximated by the third degree polynomials. On rectangular planes the approximation of an unknown source function is achieved by means of bilinear elements. A program has been developed for the parallel electromagnetic field computation based on the described method.

Modified Transceiver Antenna for NQR Detection of Explosive Objects in Demining Conditions

This paper presents the conceptual stages of the simulation and development of a modified transceiver antenna for a high-power pulsed nuclear quadrupole resonance (NQR) detector of explosives containing the 14N isotope. At a frequency of 4.645 MHz, better characteristics are obtained using a nine-turn coil shaped as half of a Fermat spiral with an outer radius of 75 mm. Using a COMSOL Multiphysics numerical parametric simulation and a materials browser, it was possible to calculate a physical system with parameters as close to reality as possible. According to the results of the experimental studies of the radio frequency (RF) energy, the proposed antenna features an increase in the working area compared to a similar antenna, the topology of the conductive coil of which has the form of an Archimedean spiral. The resulting diagrams of the distribution of the magnetic induction also indicate that the topology of the electromagnetic (EM) field does not depend on the orientation of the sample under study relative to the axis of the radial symmetry observed in square–rectangular planar antennas.

Investigation on effect of tension forces on inflatable torus for rectangular multi-layer planar membrane reflector

The membrane structures have wide application in contemporary space borne assemblies. The multi-layered reflector is used for the transmission of different radio frequency waves from satellite to the ground station. The membranes of such reflectors are kept in pre-stressed to achieve the required surface accuracy and reducing in RMS error in the surface profile. The rectangular membrane reflector is supported by inflatable torus. The tension forces and inflation pressure is the crucial factor for the design of supporting inflatable torus. The present study investigates numerically and experimentally effect of tension forces on the torus for minimum torus deflection along with the inflation pressure. The comparative study for the torus inflation pressure is made for the multi-layered membrane reflector.

An Overview of Panoramic Video Projection Schemes in the IEEE 1857.9 Standard for Immersive Visual Content Coding

Panoramic video contains 360-degree video content and it is convenient to draw the content that the user wants to watch on the head-Mount display (HMD) of the virtual reality display device. However, few encoders code panoramic video directly. Panoramic video content needs to be projected to a compression-friendly rectangular plane first. Then the existing video coding standards such as AVC, HEVC, VVC, AVS are used to code the panoramic video content. In order to improve the panoramic video coding efficiency, IEEE 1857.9 immersive video content coding working group was established to develop efficient immersive video projection and coding methods. This paper presents an overview of the panoramic video projection schemes in Immersive Visual Content Coding Standard IEEE 1857.9.

Study of the Effect of a Seismic Zone to the Construction Cost of a Five-Story Reinforced Concrete Building

Greece is divided into three earthquake hazard zones: Zone I, Zone II and Zone III. In the present research work, the same building in the three seismic zones in Greece was modeled, analyzed and dimensioned. Then, the construction cost of its structural body was estimated. The building modeling was performed in SAP2000 using frame elements. The analysis of the building was performed by dynamic spectral analysis methods using the design spectrum EC8. A five-story building with a standard rectangular floor plan per floor was used. The purpose of this research paper is to demonstrate whether the cost of construction of a load-bearing body of a reinforced concrete (R/C) building is influenced by the area of an earthquake hazard through a comparative analytical estimation of construction costs. It was determined if this impact is important and to what extent. Helpful conclusions were drawn in relation to the influence of seismicity on the construction cost of the load-bearing structure of R/C buildings. Furthermore, the probable environmental impact was examined.

A new compact grounded coplanar waveguide slotted multiband planar antenna for radio frequency identification data applications

&lt;p&gt;&lt;span&gt;This research presents the development and conception of a new compact grounded coplanar waveguide fed slotted rectangular planar antenna with a multi-frequency band for &lt;a name="_Hlk94076774"&gt;&lt;/a&gt;radio frequency identification data (RFID) reader applications which is based on the antenna mono-band frequency to use for a various applications RFID to support a different operating range. The optimized of the final prototype designing operates a multiple frequency bands ranging from 0.7-1.1 GHz, 2.2-2.5 GHz and 5.4-6 GHz for 0.9/2.4 GHz and 5.8 GHz RFID operation bands which is adapted from ultra-high frequency band (0.9 GHz) to microwave frequency band (2.4-5.8 GHz) RFID systems. This antenna is implemented and printed on a FR4 substrate with a size of 30×50×1.6 mm&lt;sup&gt;3&lt;/sup&gt;. The novel prototype includes of a radiator rectangular patch with a symmetrical slot and a U-slot with I-stub on ground plan. The principles parameters of the antenna have been studied optimized and miniaturized by using a two simulators CST Microwave Studio and advanced design system (ADS) to validate the simulation results before the planar antenna realization. The final structure is achieved and validated of the results measurement. Experimental results show that the proposed antenna with a small size has good and stable radiation and thus promising for a various RFID applications.&lt;/span&gt;&lt;/p&gt;

Numerical analysis of the performance of proton exchange membrane fuel cell with longitudinal vortex generators

To improve the performance of proton exchange membrane fuel cell (PEMFC), in this study the combination of longitudinal vortex generators (LVGs) and cathode channel is proposed to improve the power density performance and optimize the water-thermal management of PEMFC with a less pressure loss. The effects of the shape, spacing, angle of attack, and number of LVGs on the performance of PEMFC are investigated via numerical simulation. The results show that the current density of the PEMFC improved the most significantly by installing five groups of rectangular plane winglet with a 12 mm spacing and 45° angle of attack in the cathode channel, and that the peak current density increases by 33.3% with additional flow resistance loss of 164.64% than the initial design. The current density of the PEMFC increases with the increase of spacing, angle of attack, and number of vortex generator groups. Moreover, the vortex generator improves the distribution uniformity of temperature, water content, and oxygen content inside the PEMFC. Importantly, it is also observed that the secondary flow intensity of PEMFC channel is positively correlated with the current density of the PEMFC. When the angle of attack is 45°, the vorticity increases the most, i.e., 16.79% higher than that without a VG. Ultimately, the pressure drop and overall performance indicator of PEMFC with LVGs are demonstrated. Compared with the initial design, except the comprehensive performance of the 0° angle of attack has been improved, that of other schemes has been reduced. It is worth noting that, for other published optimization schemes, the research scheme proposed in this paper has certain advantages in terms of lifting current density with lower resistance loss. Therefore, it is still of great significance to improve the energy density of PEMFC.

ZONGULDAK/ÇAYCUMA’DA ÇANTI TEKNİĞİNDE İNŞA EDİLMİŞ BİR CAMİ: AKÇAHATİPLER KÖYÜ CAMİ

Wood has been the main traditional building material for centuries in the northern parts of Anatolia and has been used in different types of buildings. Mosques built with the “çantı technique”, which is defined as the wooden masonry construction system used in the Black Sea Region; although it is seen intensely in the region, it is among the cultural assets that are in danger of extinction due to the deterioration of the wooden material. Within the scope of this study, the çantı construction technique and the çantı mosque tradition in Anatolia are discussed, and the Çaycuma Akçahatipler Village Mosque, located in the Western Black Sea Region, has been examined. The study aims to reveal the characteristics of the period by making an architectural analysis of the Çaycuma Akçahatipler Village mosque, which is one of the examples of çantı mosques, and by examining both historically close and architectural features comparatively with similar examples.&#x0D; In this study, qualitative research methods such as literature research and interviews with individuals were supported by fieldwork. With the findings based on photography, on-site measurements, drawings and observations, spatial and facade analysis of Çaycuma Akçahatipler Village Mosque were made and its structural features were mentioned. The building shows a rectangular plan without a portico, developing in the direction of the north-south axis perpendicular to the mihrab wall. The corner connections of the building were constructed using the “kurtboğazı” technique, by the general situation. While the building draws attention with its monumental dimensions, it is important in terms of presenting an example of a çantı mosque located in the Western Black Sea Region and preserved until today. This study is a preliminary documentation study to increase the visibility of the structure and ensure that it is protected. It is also known that the “çantı” construction system is used not only in mosques but also in residential architecture in the village. It can be stated that the “çantı” construction system, which is a product of the 7000-year-old wooden construction tradition, is also extremely important in terms of historical continuity, with its use in buildings serving different functions in Akçahatipler Village.

Ultrahigh dose rate pencil beam scanning proton dosimetry using ion chambers and a calorimeter in support of first in-human FLASH clinical trial.

PurposeTo provide ultrahigh dose rate (UHDR) pencil beam scanning (PBS) proton dosimetry comparison of clinically used plane‐parallel ion chambers, PTW (Physikalisch‐Technische Werkstaetten) Advanced Markus and IBA (Ion Beam Application) PPC05, with a proton graphite calorimeter in a support of first in‐human proton FLASH clinical trial.MethodsAbsolute dose measurement intercomparison of the plane‐parallel plate ion chambers and the proton graphite calorimeter was performed at 5‐cm water‐equivalent depth using rectangular 250‐MeV single‐layer treatment plans designed for the first in‐human FLASH clinical trial. The dose rate for each field was designed to remain above 60 Gy/s. The ion recombination effects of the plane‐parallel plate ion chambers at various bias voltages were also investigated in the range of dose rates between 5 and 60 Gy/s. Two independent model‐based extrapolation methods were used to calculate the ion recombination correction factors ks to compare with the two‐voltage technique from most widely used clinical protocols.ResultsThe mean measured dose to water with the proton graphite calorimeter across all the predefined fields is 7.702 ± 0.037 Gy. The average ratio over the predefined fields of the PTW Advanced Markus chamber dose to the calorimeter reference dose is 1.002 ± 0.007, whereas the IBA PPC05 chamber shows ∼3% higher reading of 1.033 ± 0.007. The relative differences in the ks values determined from between the linear and quadratic extrapolation methods and the two‐voltage technique for the PTW Advanced Markus chamber are not statistically significant, and the trends of dose rate dependence are similar. The IBA PPC05 shows a flat response in terms of ion recombination effects based on the ks values calculated using the two‐voltage technique. Differences in ks values for the PPC05 between the two‐voltage technique and other model‐based extrapolation methods are not statistically significant at FLASH dose rates. Some of the ks values for the PPC05 that were extrapolated from the three‐voltage linear method and the semiempirical model were reported less than unity possibly due to the charge multiplication effect, which was negligible compared to the volume recombination effect in FLASH dose rates.ConclusionsThe absolute dose measurements of both PTW Advanced Markus and IBA PPC05 chambers are in a good agreement with the National Physical Laboratory graphite calorimeter reference dose considering overall uncertainties. Both ion chambers also demonstrate good reproducibility as well as stability as reference dosimeters in UHDR PBS proton radiotherapy. The dose rate dependency of the ion recombination effects of both ion chambers in cyclotron generated PBS proton beams is acceptable and therefore, both chambers are suitable to use in clinical practice for the range of dose rates between 5 and 60 Gy/s.

Non-iterative division circuit design with accuracy and performance trade-off based on mixed integer linear programming approach

A wide range of applications such as image/video processing involve arithmetic division and demand high computing performance but can tolerate some degree of errors or allow small deviations from their theoretical results. This paper presents an approach for non-iterative arithmetic division circuit design, leveraging computation accuracy for high performance. The quotient is modeled as a curved surface and the surface is partitioned into many small rectangular planar stripes for linearity. Mixed integer linear programming is adopted to optimize the worst case error due to approximation in each stripe. As a result, an architecture for the division circuits consisting of simple additions and a small look-up table is achieved. The accuracy achieved in terms of the maximum absolute error percentage (MAEP) ranges from 0.44% to 0.11%. Comparing the proposed designs with the existing counterparts with similar MAEP, the area-delay product (ADP) is reduced by more than 40%. Compared to the counterpart with the closest ADP by the single stage logarithmic method, the proposed circuit has a smaller MAEP with 45% reduction. Comparing with the existing non-iterative division circuit by the curve fitting method, the proposed circuit has lowered MAEP and ADP by 21% and 27% respectively.

Reconfigurable Inverted U Slot Antenna with Switching Mechanism for Wireless Applications

Frequency reconfigurable antennas are mostly used for many wireless applications. The proposed antenna uses a PIN diode to switch between 2.45 to 3.93 GHz. The ultra-wideband is obtained by a partial rectangular ground plane with an inverted U slot and the narrowband is obtained by adding a parasitic element electrically connected to the ground by positive bias of PIN diode. Frequency Reconfigurable antennas can adjust dynamically its frequency of operation as per the requirement. For better designing of antenna and to get better accurate results, we usually change the physical dimensions of the antenna. It is lengthy and time taking process if we consider this method. Comparison and selection in designing of antennas will be difficult if we keep on changing the dimensions. So, we prefer Reconfigurability.