Search

With the increase in the usage of electromagnetic devices, electromagnetic interference increased many folds. Frequency Selective Surface (FSS) provide effective shielding from unwanted frequency ranges. A thin, conformal band-stop FSS is presented in this research that provides effective electromagnetic shielding properties in X-band. The FSS acts as a band stop filter at 10 GHz. The proposed FSS has 54.7% fractional bandwidth. The design is of the dimensions 6.79 x 6.79 x 0.127 milimeter cube, employing Rogers RT 5880 substrate with 0.0009 dielectric constant. It has an attenuation of at least -57.97 dB. The proposed FSS shows oblique incidence angle independence for both TE and TM modes, up to 60o scan angle. The incidence angle independence makes the FSS response stable for both normal and varying angles of the incident waves. The design has a copper cladding of 0.018 mm, making the overall FSS thickness of 0.145 mm. The thin substrate makes the design flexible and easily bendable for curved surfaces. Its thin structure makes it easily applicable on buildings, vehicles and military aircrafts for electromagnetic shielding purposes. The conformability and shielding properties make the design suitable for various other applications.

Content-adaptive steganography intends to hide data in the complex texture content of the image. Recently, some secure steganography methods have been proposed to identify the textural complexity of an image. However, most of the techniques do not take into account the information of pixel variation around the central pixel in all possible directions and therefore they are unable to accurately analyse the texture complexity. This work offers a quality-enhanced and secure method of content-adaptive image steganography. The proposed method is divided into three sequential steps: image segmentation, pixel complexity identification, and data embedding. An input cover image is initially divided into small local regions and the pixel-complexity is identified based on the proposed Complex Block Prior (CBP) criterion. In a local block, a high pass filter (HPF) bank is applied and eight residual responses are obtained. Following the CBP criterion, a complexity level out of nine levels is assigned to an individualized pixel block. The pixels are then arranged in the priority of complexity from highest to lowest. Data embedding for the corresponding complexity level then takes place using the proposed adaptive embedding algorithm. Experimental results verify the preservation of visual quality of stego images produced by the proposed method. Three image datasets: Standard test images, BOWS2 and BOSS-base are used for the experimentation and comparison with prior state-of-art methods. Highest values of the IQ (image quality) parameters e.g., SSIM and WPSNR show the effectiveness of the proposed method.

Flood forecasting in a transboundary river basin is challenging due to insufficient data sharing between countries in the upper and lower reaches of a basin. A solution is the use of satellite-observed rainfall and numerical weather prediction (NWP) for hydrological forecasting. We applied this method to the transboundary sparsely gauged Chenab River basin in Pakistan and India to reproduce the exceptionally high flood in 2014. We employed global NWPs by three weather centers to consider forecast uncertainty and downscaled them using the Weather Research and Forecasting (WRF) Model to prepare precipitation inputs. For hydrological simulations, we used a kinematic wave model, the Integrated Flood Analysis System (IFAS), for the upper-reach basin with high mountains and steep slopes, and we used a diffusive-wave rainfall–runoff–inundation (RRI) model for low altitudes and mild slopes. In our forecasting experiment, the precipitation by the global NWP was not able to predict flood peaks consistently. However, the downscaled rainfall by regional NWP showed good performance in predicting flood waves quantitatively, and a multimodel approach provided added value in issuing reliable warning as early as 6 days in advance. A confident streamflow forecasting near the border of the countries also led to reliable inundation forecasting by the RRI model in the lower-reach basin.

In this paper a novel, compact 10-bit chipless radio frequency identification (RFID) tag with stable readable characteristics is proposed. The tag is composed of several concentric novel kite-shape...

This paper presents the design of a microstrip ultra-wideband (UWB) bandpass filter that exhibits desirable characteristics of low-loss, high selectivity, wide stopband and high out-of-band rejection at room temperature. These characteristics are normally achieved with high temperature superconductor filters that require cryogenic cooling. The design of the proposed filter was realized by exciting multiple resonant modes in a unique Z-shaped microstrip resonator. The admittance of the filter configuration can be tuned prior to fabrication to adjust its center frequency by about 11.5% without affecting the profile of the bandpass response however this can have an impact of the loss. The proposed configuration allows adjustment of the upper and lower transmission zeros defining the bandpass response by 20.5% and 11.4%, respectively, without degrading the overall filter response. The low-loss quasi-elliptic function UWB bandpass filter design was fabricated on a commercially available dielectric substrate using standard PCB technology and its performance verified. The fabricated filter exhibits insertion-loss of 0.68 dB and return-loss better than 17 dB.

A robustness-driven hybrid descriptor (RDHD) for noise-deterrent texture classification is presented in this paper. This paper offers the ability to categorize a variety of textures under challenging image acquisition conditions. An image is initially resolved into its low-frequency components by applying wavelet decomposition. The resulting low-frequency components are further processed for feature extraction using completed joint-scale local binary patterns (CJLBP). Moreover, a second feature set is obtained by computing the low order derivatives of the original sample. The evaluated feature sets are integrated to get a final feature vector representation. The texture-discriminating performance of the hybrid descriptor is analyzed using renowned datasets: Outex original, Outex extended, and KTH-TIPS. The experimental results demonstrate a stable and robust performance of the descriptor under a variety of noisy conditions. An accuracy of 95.86%, 32.52%, and 88.74% at noise variance of 0.025 is achieved for the given datasets, respectively. A comparison between performance parameters of the proposed paper with its parent descriptors and recently published paper is also presented.

In this work, an integrated antenna system with Defected Ground Structure (DGS) is presented for Fourth Generation (4G) and millimeter (mm)-wave Fifth Generation (5G) wireless applications and handheld devices. The proposed design with overall dimensions of 110 mm × 75 mm is modeled on 0.508 mm thick Rogers RT/Duroid 5880 substrate. Radiating structure consists of antenna arrays excited by the T-shape 1 × 2 power divider/combiner. Dual bands for 4G centered at 3.8 GHz and 5.5 GHz are attained, whereas the 10-dB impedance bandwidth of 24.4 - 29.3 GHz is achieved for the 5G antenna array. In addition, a peak gain of 5.41 dBi is demonstrated across the operating bandwidth of the 4G antenna array. Similarly, for the 5G mm-wave configuration the attained peak gain is 10.29 dBi. Moreover, significant isolation is obtained between the two antenna modules ensuring efficient dual-frequency band operation using a single integrated solution. To endorse the concept, antenna prototype is fabricated and far-field measurements are procured. Simulated and measured results exhibit coherence. Also the proposed design is investigated for the beam steering capability of the mm-wave 5G antenna array using CST®MWS®. The demonstrated structure offers various advantages including compactness, wide bandwidth, high gain, and planar configuration. Hence, the attained radiation characteristics prove the suitability of the proposed design for the current and future wireless handheld devices.

Lignocelluloses’ pretreatment is targeted for the improvement of hydrolysis of their carbohydrates, i.e., cellulose and hemicelluloses. Modification of the hardheaded structure of lignocelluloses is a fundamental stair in biofuels and biochemicals production. The high crystalline configurations of cellulose embed with hemicelluloses and lignin, give rise to recalcitrance structure. Second-generation biofuel production processes, using lignocellulosic biomass as a feedstock, is based on a three-stage process, including pretreatment, enzymatic hydrolysis, and fermentation. The pretreatment stage is the most critical, influencing, costly stage. The perfect pretreatment process is designated to provide minimum cellulosic crystallinity with remarkable low lignin content as well as inhibitory compounds through a sustainable economical process. In the present review, advances in lignocellulosic pretreatment technologies for biofuels production are reviewed and critically discussed. The article further discusses the pros and cons of the various pretreatment methodologies as well as addresses the role and impact of different process parameters associated with the pretreatment process.

In this research paper, a Novel, compact, low cost and entirely passive Chipless radio frequency identification tag are presented. The tag design comprises of 10 half cut cross loop-shaped resonant elements where each resonant element is represented by one encoding bit in the frequency domain. The tag has a compact geometrical footprint of 10.8×10.8mm2. The electromagnetic performance analysis of the tag is done by using multiple substrates Rogers RT/Duroid/5880, Rogers RT/Duroid/5870 and Taconic TLX-0. The Physical dimension of the proposed tag design is relatively small with very high bit capacity of 8.57 bits/cm2 and spectral efficiency of 2.5 bits/GHz. The proposed tag design possesses the ability to generate 210 unique IDs for the identification process of various objects. The proposed tag operates in license-free UWB band having a frequency band of 3.5 GHz to 7.5 GHz. The proposed tag is appropriate to be deployed in the field of Internet of Things.

This paper describes the design and evaluation of a highly selective wideband microstrip bandpass filter with a near brick-shaped transmission response and a very wide stopband characteristic. The proposed filter structure excites multimode resonances that combine to realize a wideband filter response and excited too are transmission zeros that create a highly selective filter with wideband suppression in the upper and lower stopbands. The filter configuration comprises electromagnetically coupled resonators that are stub loaded. The input and output feedlines are interdigitally coupled to the resonators. Measured results confirm the low-loss and via-free wideband filter exhibits an elliptical response with a wide stopband with a rejection greater than 30 dB. The selectivity factor and stopband performance of the proposed filter is better than that obtained with the high-temperature superconductor (HTS) filters. Design of the filter is relatively simple and easy to manufacture using standard PCB technology. There is good correlation between the simulation and measured results. The proposed wideband bandpass filter is suitable for applications in high interference environments and cognitive radio systems.

A compact chipless RFID tag with robust readable features is presented in this paper. The tag is made up of novel concentric butterfly slot resonators. Bit data is encoded in the frequency signature of the tag. Each slot corresponds to a resonance peak representing a bit ‘1’, whereas an absence of the peak signifies a bit ‘0’. Proposed resonator design demonstrates insensitivity to different polarization and incident angles of the linearly polarized impinging electromagnetic wave. The tag operates in the frequency band of 4.7-9.7 GHz, limited within the license-free ultra wide-band. Rogers RT/duroid (R) 5880 substrate is used to realize a 10-bit capacity design that spans 14 times 14 sq. mm resulting in a bit density of 5.1 bits/sq. cm.

In this paper, a compact and fully passive bit encoding circuit, capable of operating as a chipless radio frequency identification (RFID) tag is presented. The structure consists of novel concentric trefoil-shaped slot resonators realized using Rogers RT/duroid® 5880 laminate, occupying a physical footprint of 13.55 $\times $ 13.55 mm2. Each resonating element is associated with a particular data bit, having a 1:1 resonator-to-bit correspondence. Bit sequences are configured through introducing modifications in the geometric structure either by addition or exclusion of each nested slot resonator. Such changes manifest directly in the electromagnetic signature of the tag as presence or absence of corresponding resonant peaks. The proposed 10-bit tag offers minimized inter-resonator mutual coupling and insensitivity to changes in polarization and incident angles thereby demonstrating orientation independent functionality. Moreover, error-free encoding is achieved through stabilizing the shift in resonant frequencies for a variety of different geometric configurations and orientation of the structure. The tag operates within the license-free ultra-wideband ranging from 5.4 to 10.4 GHz, providing spectral bit capacity and bit density of 2 bits/GHz and 5.44 bits/cm2 respectively.

A compact, robust, chipless radio frequency identification (RFID) tag is proposed. Resonant elements patterned in a concentric fashion encode data in the spectral domain employing frequency shift e ...

A polarization insensitive, compact, fully-passive bit encoding structure exhibiting 1 : 1 resonator-to-bit correspondence is presented. Inspired by frequency selective surface (FSS) based microwav ...

A novel, frequency selective surface (FSS) inspired, fully passive, chipless data encoding circuit capable of being operated as a radio frequency identification (RFID) tag is presented. The tag is ...

A novel, frequency selective surface (FSS) based, data encoding structure amenable to be used as a chipless RFID tag is proposed. The data encoding structure is made up of finite repetitions of a u ...

Hybrid wind systems couple wind turbines with storage and/or other generation technologies to maximize wind energy production while meeting operational requirements in terms of frequency control, regulation, load following, and scheduling. To increase fuel savings and emission reductions, a hierarchical control structure is proposed in this paper that combines supervisory control and component local control. In supervisory control, unit commitment and power dispatch are optimized and communicated to component local controllers. Frequency/voltage droop (P/Q droop) functions are developed for battery banks and diesel units to regulate system frequency and voltage. PSCAD simulation results indicate that the proposed hierarchical control strategy enables high wind penetration without compromising system performance.