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Effect of Dy-substitution on structural and magnetic properties of Mn-Zn ferrite nanoparticles

Journal of Rare Earths 2018年第1期36卷 86-94页

作者： K.V.Zipare S.S.Bandgar G.S.Shahane department of electronics DBF Dayanand College of Arts and Science

This paper describes the structural and magnetic properties of Dy-substituted Mn-Zn ferrite nano- particles. Mn-Zn-Dy ferrite nanopafficles of the composition ***204 （x- 0.05, 0.1, 0.15 and 0.2） were synthesized by a facile chemical co-precipitation method. The samples were characterized through X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR）, vibrating sample magnetometer （VSM） and Curie temperature. The XRD patterns confirm the synthesis of single crystalline phase of Mn-Zn-Dy ferrite nanoparticles. Lattice parameter increases with increase in Dy-substitution which confirms the replacement of Fe3＋ ions by Dy3＋ ions. Crystallite size is of the order of 6-8 nm for all these samples. The particle sizes observed from TEM analysis are in good agreement with the XRD values. The magnetic measurements show super- paramagnetic nature of the samples. The saturation magnetization decreases with increase in Dy- concentration and can be correlated to modifications in the A-B exchange interactions as a result of the structural modifications due to Dy-substitution. The Curie temperature for ***204 nano- particles is 124 ℃ and decreases up to 84 ℃with the increase in the Dy-concentration. The decrease in Curie temperature can be attributed to the weakening of the superexchange interaction between A-site and B-site as a result of Dy-substitution. The low value of Curie temperature and higher value of ther- momagnetic coefficient kT shown by these samples makes them suitable for the preparation of tem- perature sensitive ferrofiuid for heat transfer applications.

关键词： Mn-Zn-Dy ferritesStructural characterizationMagnetic propertiesCurie temperatureRare earths

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Design of area and power efficient Radix-4 DIT FFT butterfly unit using floating point fused arithmetic

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Journal of Central South University 2016年第7期23卷 1669-1681页

作者： Prabhu E Mangalam H Karthick S department of electronics and Communication Engineering Amrita School of EngineeringCoimbatore Amrita Vishwa Vidyapeetham Amrita University department of electronics and Communication Engineering Sri Krishna College of Engineering and Technology department of electronics and Communication Engineering Bannari Amman Institute of Technology

In this work, power efficient butterfly unit based FFT architecture is presented. The butterfly unit is designed using floating-point fused arithmetic units. The fused arithmetic units include two-term dot product unit and add-subtract unit. In these arithmetic units, operations are performed over complex data values. A modified fused floating-point two-term dot product and an enhanced model for the Radix-4 FFT butterfly unit are proposed. The modified fused two-term dot product is designed using Radix-16 booth multiplier. Radix-16 booth multiplier will reduce the switching activities compared to Radix-8 booth multiplier in existing system and also will reduce the area required. The proposed architecture is implemented efficiently for Radix-4 decimation in time(DIT) FFT butterfly with the two floating-point fused arithmetic units. The proposed enhanced architecture is synthesized, implemented, placed and routed on a FPGA device using Xilinx ISE tool. It is observed that the Radix-4 DIT fused floating-point FFT butterfly requires 50.17% less space and 12.16% reduced power compared to the existing methods and the proposed enhanced model requires 49.82% less space on the FPGA device compared to the proposed design. Also, reduced power consumption is addressed by utilizing the reusability technique, which results in 11.42% of power reduction of the enhanced model compared to the proposed design.

关键词： floating-point arithmetic floating-point fused dot product Radix-16 booth multiplier Radix-4 FFT butterfly fast fouriertransform decimation in time

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A new approach to learning and recognizing leaf diseases from individual lesions using convolutional neural networks

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Information Processing in Agriculture 2023年第1期10卷 11-27页

作者： Lawrence C.Ngugi Moataz Abdelwahab Mohammed Abo-Zahhad department of electronics and Communication Engineering Egypt-Japan University of Science and TechnologyAlexandriaEgypt department of Electrical and electronics Engineering Assiut UniversityAssiutEgypt

Leaf disease recognition using image processing and deep learning techniques is currently a vibrant research *** studies have focused on recognizing diseases from images of whole *** approach limits the resulting models’ability to estimate leaf disease severity or identify multiple anomalies occurring on the same *** studies have demonstrated that classifying leaf diseases based on individual lesions greatly enhances disease recognition *** those studies,however,the lesions were laboriously cropped by *** study proposes a semi-automatic algorithm that facilitates the fast and efficient preparation of datasets of individual lesions and leaf image pixel maps to overcome this *** datasets were then used to train and test lesion classifier and semantic segmentation Convolutional Neural Network(CNN)models,*** report that GoogLeNet’s disease recognition accuracy improved by more than 15%when diseases were recognized from lesion images compared to when disease recognition was done using images of whole leaves.A CNN model which performs semantic segmentation of both the leaf and lesions in one pass is also proposed in this *** proposed KijaniNet model achieved state-of-the-art segmentation performance in terms of mean Intersection over Union(mIoU)score of 0.8448 and 0.6257 for the leaf and lesion pixel classes,*** terms of mean boundary F1 score,the KijaniNet model attained 0.8241 and 0.7855 for the two pixel classes,***,a fully automatic algorithm for leaf disease recognition from individual lesions is *** algorithm employs the semantic segmentation network cascaded to a GoogLeNet classifier for lesion-wise disease *** proposed fully automatic algorithm outperforms competing methods in terms of its superior segmentation and classification performance despite being trained on a small dataset.

关键词： Deep learning Precision agriculture Leaf disease recognition Complex background removal Leaf image segmentation Lesion classification

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A comparison study of on-chip short pulse generation circuits based on a coplanar waveguide

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Chinese Physics C 2011年第3期35卷 278-281页

作者：邹焕耿永涛王平山李家胤 department of Electrical and Computer Engineering Clemson University department of Physical electronics University of Electronics Science and Technology of China

A few traditional pulse-forming circuits are implemented in a commercial 0.13 μm digital complementary-metal-oxide-semiconductor （CMOS） technology. These circuits, based on a coplanar waveguide, are analyzed and compared through CadenceTM Spectre simulations. The results show that these traditional pulse-forming-line （PFL） based circuits can be implemented in standard CMOS technology for short pulse generations. Further work is needed to explore the potential of the circuit techniques and to minimize parasitic effects.

关键词： pulse generation circuit transmission line PFL CMOS coplanar waveguide

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Path Weight Complementary Convolutional Code for Type-Ⅱ Bit-Interleaved Coded Modulation Hybrid ARQ System

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Tsinghua Science and Technology 2007年第S1期12卷 240-245页

作者：程宇新张磊依那项海格 department of electronics Peking University

Bit-interleaved coded modulation (BICM) is suitable to bandwidth-efficient communication systems. Hybrid automatic repeat request (HARQ) can provide more reliability to high-speed wireless data transmission. A new path weight complementary convolutional (PWCC) code used in the type-Ⅱ BICM-HARQ system is proposed. The PWCC code is composed of the original code and the complimentary code. The path in trellis with large hamming weight of the complimentary code is designed to compensate for the path in trellis with small hamming weight of the original code. Hence, both of the original code and the complimentary code can achieve the performance of the good code criterion of corresponding code rate. The throughput efficiency of the BICM-HARQ system wit PWCC code is higher than repeat code system, a little higher than puncture code system in low signal-to-noise ratio (SNR) values and much higher than puncture code system, the same as repeat code system in high SNR values. These results are confirmed by the simulation.

关键词： bit-interleaved coded modulation type-II hybrid automatic repeat request path weight comple- mentary convolutional code throughput efficiency

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A fuzzy-logic-based approach to accurate modeling of a double gate MOSFET for nanoelectronic circuit design

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Journal of Semiconductors 2012年第9期33卷 43-49页

作者： F.Djeffal A.Ferdi M.Chahdi LEA Department of ElectronicsUniversity of Batna05000 BatnaAlgeria LEPCM Department of ElectronicsUniversity of Batna05000 BatnaAlgeria

The double gate （DG） silicon MOSFET with an extremely short-channel length has the appropriate fea- tures to constitute the devices for nanoscale circuit design. To develop a physical model for extremely scaled DG MOSFETs, the drain current in the channel must be accurately determined under the application of drain and gate voltages. However, modeling the transport mechanism for the nanoscale structures requires the use of overkill meth- ods and models in terms of their complexity and computation time （self-consistent, quantum computations ）. Therefore, new methods and techniques are required to overcome these constraints. In this paper, a new approach based on the fuzzy logic computation is proposed to investigate nanoscale DG MOSFETs. The proposed approach has been implemented in a device simulator to show the impact of the proposed approach on the nanoelectronic cir- cuit design. The approach is general and thus is suitable for any type ofnanoscale structure investigation problems in the nanotechnology industry.

关键词： nanoscale circuit DG MOSFET fuzzy modelling computational cost circuit design

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An Investigation of Ionic Flows in a Sphere-Plate Electrode Gap

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Plasma Science and Technology 2013年第10期15卷 1012-1019页

作者： H.Z.ALISOY S.ALAGOZ G.T.ALISOY B.B.ALAGOZ department of Electrical-electronics Inonu University department of Physics Inonu University department of Mathematics Inonu University

This paper presents analyses of ion flow characteristics and ion discharge pulses in a sphere-ground plate electrode system. As a result of variation in electric field intensity in the electrode gap, the ion flows towards electrodes generate non-uniform discharging pulses. Inspection of these pulses provides useful information on ionic stream kinetics, the effective thickness of ion cover around electrodes, and the timing of ion clouds discharge pulse sequences. A finite difference time domain （FDTD） based space-charge motion simulation is used for the numerical analysis of the spatio-temporal development of ionic flows following the first Townsend avalanche, and the simulation results demonstrate expansion of the positive ion flow and compression of the negative ion flow, which results in non-uniform discharge pulse characteristics.

关键词： ion flow FDTD simulation space charge motion

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Void defect detection in ball grid array X-ray images using a new blob filter

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Journal of Zhejiang University-Science C(Computers and electronics) 2012年第11期13卷 840-849页

作者： Shao-hu PENG Hyun Do NAM department of electronics and Electrical Engineering Dankook University

Ball grid arrays (BGAs) have been used in the production of electronic devices/assemblies because of their advantages of small size, high I/O port density, etc. However, BGA voids can degrade the performance of the board and cause failure. In this paper, a novel blob filter is proposed to automatically detect BGA voids presented in X-ray images. The proposed blob filter uses the local image gradient magnitude and thus is not influenced by image brightness, void position, or component interference. Different sized average box filters are employed to analyze the image in multi-scale, and as a result, the proposed blob filter is robust to void size. Experimental results show that the proposed method obtains void detection accuracy of up to 93.47% while maintaining a low false ratio. It outperforms another recent algorithm based on edge detection by 40.69% with respect to the average detection accuracy, and by 16.91% with respect to the average false ratio.

关键词： Ball grid array (BGA) X-ray Defect detection Blob detection Void detection

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Phonon States and Dispersive Spectra of Polar Optical Phonons in Quasi-One-Dimensional Nanowires of Wurtzite ZnO and Zinc-Blend MgO Semiconductors

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Communications in Theoretical Physics 2011年第1期55卷 176-184页

作者：张立 department of Mechanism and electronics Guangzhou Panyu Polytechnic

Within the framework of the macroscopic dielectric continuum model and Loudon＇s uniaxial crystal model, the phonon modes of a wurtzite/zinc-blende one-dimensional （1D） cylindrical nanowire （NW） are derived and studied. The analytical phonon states of phonon modes are given. It is found that there exist two types of polar phonon modes, i.e. interface optical （IO） phonon modes and the quasi-confined （QC） phonon modes existing in 1D wurtzite/zinc-blende NWs. Via the standard procedure of field quantization, the Fr6hlich electron-phonon interaction Hamiltonians are obtained. Numerical calculations of dispersive behavior of these phonon modes on a wurtzite/zinc-blende ZnO/MgO NW are performed. The frequency ranges of the IO and QC phonon modes of the ZnO/MgO NWs are analyzed and discussed. It is found that the IO modes only exist in one frequency range, while QC modes may appear in three frequency ranges. The dispersive properties of the IO and QC modes on the free wave-number kz and the azimuthal quantum number m are discussed. The analytical Hamiltonians of electron-phonon interaction obtained here are quite useful for further investigating phonon influence on optoelectronics properties of wurtzite/zinc-blende 1D NW structures.

关键词： ZnO/MgO nanowires surface optical and quasi-confine phonon modes electron-phonon interactions

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Noether's theory of generalized linear nonholonomic mechanical systems

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Chinese Physics B 2011年第1期20卷 61-68页

作者：董文山黄宝歆方建会 department of Physics and electronics Science University of Weifang department of Applied Physics University of Petroleum

By introducing the quasi-symmetry of the infinitesimal transformation of the transformation group Gr, the Noether＇s theorem and the Noether＇s inverse theorem for generalized linear nonholonomic mechanical systems are obtained in a generalized compound derivative space. An example is given to illustrate the application of the result.

关键词： generalized linear nonholonomic mechanics symmetry conserved quantity Noether'stheory

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