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Orthogonal waveform design with fractional programming on the ambiguity suppression of SAR systems

Science China(Information Sciences) 2024年第9期67卷 263-279页

作者： Yunkai DENG Yongwei ZHANG Zhimin ZHANG Wei WANG Heng ZHANG department of Space microwave Remote Sensing System Aerospace Information Research InstituteChinese Academy of Sciences

Waveform diversity(WD) represents a dynamic and transformative technology widely used in radar systems to enhance sensitivity and discrimination capabilities. Recently, WD techniques have been extensively explored for their potential ambiguity suppression within synthetic aperture radar(SAR) *** these, the alternate transmitting mode combined with orthogonal waveforms emerges as a particularly promising solution. This study focuses on optimizing the power spectrum density(PSD) of signals to design and generate an orthogonal waveform pair that achieves both a low cross-correlation-to-autocorrelation ratio(CAR) and satisfactory imaging performance. Initially, we construct a fractional programming model with convex constraints to minimize the CAR. To address this challenge, we introduce an iterative optimization procedure for the PSD variable, which sequentially reduces the CAR. Each optimization step can be efficiently solved using a quadratically constrained quadratic program, ensuring that the resulting computational complexity remains low. Building on the optimized PSD, we established a parametric piecewise linear model to generate an orthogonal waveform pair. This model not only maintains a low CAR but achieves satisfactory imaging performance in real-time applications. Consequently, this orthogonal waveform pair effectively suppresses range ambiguity in SAR systems. Finally, we demonstrated the practicability and effectiveness of the proposed orthogonal waveforms through detailed simulation experiments, specifically targeting ambiguity suppression in conventional quad-polarization SAR systems.

关键词： synthetic aperture radar (SAR) waveform diversity (WD) ambiguity suppression orthogonal waveform fractional programming power spectrum density (PSD)

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Analog spatiotemporal feature extraction for cognitive radio-frequency sensing with integrated photonics

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Light(Science & Applications) 2024年第3期13卷 478-487页

作者： Shaofu Xu Binshuo Liu Sicheng Yi Jing Wang Weiwen Zou State Key Laboratory of Advanced Optical Communication Systems and Networks Intelligent Microwave Lightwave Integration Innovation Center(imLic)Department of Electronic EngineeringShanghai Jiao Tong UniversityShanghaiChina

Analog feature extraction(AFE)is an appealing strategy for low-latency and efficient cognitive sensing systems since key features are much sparser than the Nyquist-sampled ***,applying AFE to broadband radio-frequency(RF)scenarios is challenging due to the bandwidth and programmability bottlenecks of analog electronic ***,we introduce a photonics-based scheme that extracts spatiotemporal features from broadband RF signals in the analog *** feature extractor structure inspired by convolutional neural networks is implemented on integrated photonic circuits to process RF signals from multiple antennas,extracting valid features from both temporal and spatial *** of the tunability of the photonic devices,the photonic spatiotemporal feature extractor is trainable,which enhances the validity of the extracted ***,a digital-analog-hybrid transfer learning method is proposed for the effective and low-cost training of the photonic feature *** validate our scheme,we demonstrate a radar target recognition task with a 4-GHz instantaneous *** results indicate that the photonic analog feature extractor tackles broadband RF signals and reduces the sampling rate of analog-to-digital converters to 1/4 of the Nyquist sampling while maintaining a high target recognition accuracy of 97.5%.Our scheme offers a promising path for exploiting the AFE strategy in the realm of cognitive RF sensing,with the potential to contribute to the efficient signal processing involved in applications such as autonomous driving,robotics,and smart factories.

关键词： scheme driving smart

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Effect of the Si-doped In_(0.49)Ga_(0.51)P barrier layer on the device performance of In_(0.4)Ga_(0.6)As MOSFETs grown on semi-insulating GaAs substrates

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Chinese Physics B 2013年第7期22卷 463-466页

作者：常虎东孙兵薛百清刘桂明赵威王盛凯刘洪刚 microwave device and ic department Institute of MicroelectronicsChinese Academy of Sciences

In0.4Ga0.6As channel metal-oxide-semiconductor field-effect transistors （MOSFETs） with and without an Si-doped In0.49Ga0.51P barrier layer grown on semi-insulating GaAs substrates have been investigated for the first time. Compared with the In0.4Ga0.6As MOSFETs without an In0.49Ga0.51P barrier layer, In0.4Ga0.6As MOSFETs with an In0.49Ga0.51P barrier layer show higher drive current, higher transconductance, lower gate leakage current, lower subthreshold swing, and higher effective channel mobility. These In0.4Ga0.6As MOSFETs （gate length 2 μm） with an In0.49Ga0.51P barrier layer exhibit a high drive current of 117 mA/mm, a high transconductance of 71.9 mS/mm, and a maximum effective channel mobility of 1266 cm2/（V·s）.

关键词： metal–oxide–semiconductor field-effect transistor InGaAs InGaP Al2O3

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High-mobility germanium p-MOSFETs by using HCl and(NH_4)_2S surface passivation

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Chinese Physics B 2013年第10期22卷 504-507页

作者：薛百清王盛凯韩乐常虎东孙兵赵威刘洪刚 microwave device and ic department Institute of MicroelectronicsChinese Academy of Sciences

To achieve a high-quality high-κ/Ge interfaces for high hole mobility Ge p-MOSFET applications, a simple chemical cleaning and surface passivation scheme is introduced, and Ge p-MOSFETs with effective channel hole mobility up to 665 cm2/V.s are demonstrated on a Ge （111） substrate. Moreover, a physical model is proposed to explain the dipole layer formation at the metal-oxide-semiconductor （MOS） interface by analyzing the electrical characteristics of HCl- and （NH4）2S-passivated samples.

关键词： Ge MOSFET high-k dielectric mobility

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Assembly of functional carboxymethyl cellulose/polyethylene oxide/anatase TiO_(2) nanocomposites and tuning the dielectric relaxation, optical, and photoluminescence performances

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Journal of Semiconductors 2024年第7期45卷 26-38页

作者： Asmaa M.Ismail Abeer A.Reffaee Fawzy G.El Desouky Spectroscopy department Physics Research InstituteNational Research CentreGizaCairo 12622Egypt microwave Physics and Dielectrics department National Research CentreDokkiCairoEgypt Solid State Physics department Physics Research InstituteNational Research CentreGizaCairo 12622Egypt

Nanocomposite films consisting of carboxymethyl cellulose,polyethylene oxide(CMC/PEO),and anatase titanium diox-ide(TO)were produced by the use of sol-gel and solution casting ***2 nanocrystals were effectively incorporated into CMC/PEO polymers,as shown by X-ray diffraction(XRD)and attenuated total reflectance fourier transform infrared(ATR-FTIR)*** roughness growth is at high levels of TO nanocrystals(TO NCs),which means increasing active sites and defects in CMC/*** differential scanning calorimetry(DSC)thermograms,the change in glass transition temperature(Tg)val-ues verifies that the polymer blend interacts with TO *** increment proportions of TO NCs have a notable impact on the dielectric performances of the nanocomposites,as *** electrical properties of the CMC/PEO/TO nanocomposite undergo significant *** nanocomposite films exhibit a red alteration in the absorption edge as the concentration of TO NCs increases in the polymer *** decline in the energy gap is readily apparent as the weight percentage of TO NCs *** photoluminescence(PL)emission spectra indicate that the sites of the luminescence peak maximums show slight variation;peaks get wider,while their intensities decrease dramatically as the concentration of TO *** nanocomposite materials show potential for multifunctional applications including optoelectronics,antireflection coatings,pho-tocatalysis,light emitting diodes,and solid polymer electrolytes.

关键词： anatase TiO_(2) CMC/PEO nanocomposites optical photoluminescent electrical optoelectronics

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The microwave Characteristics of an In_(0.4)Ga_(0.6)As Metal-Oxide-Semiconductor Field-Effect Transistor with an In_(0.49)Ga_(0.51)P Interfacial Layer

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Chinese Physics Letters 2013年第8期30卷 160-163页

作者： LIU Gui-Ming CHANG Hu-Dong SUN Bing LIU Hong-Gang microwave device and ic department Institute of MicroelectronicsChinese Academy of SciencesBeijing 100029

A high microwave performance enhancement-mode(E-mode)In_(0.4)Ga_(0.6)As channel metal-oxide-semiconductor field-effect transistor(MOSFET)with a Si-doped In_(0.49)Ga0.51P interfacial layer is fabricated.A 0.8-μm-gate-length In_(0.4)Ga_(0.6)As MOSFET with a 5-nm Al_(2)O_(3) dielectric layer provides a current gain cutoff frequency of 16.7 GHz and a maximum oscillation frequency of 52 GHz.A semi-empirical small-signal-parameter extraction technique accounting for the low frequency anomaly of this MOSFET device is described,which is based on on-wafer S-parameter *** agreement between measured and simulated scattering parameters as well as the physically realistic circuit elements demonstrates the validity of this approach.

关键词： scattering transistor parameter

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High-Quality Single Crystalline Ge(111)Growth on Si(111)Substrates by Solid Phase Epitaxy

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Chinese Physics Letters 2012年第3期29卷 154-156页

作者： SUN Bing CHANG Hu-Dong LU Li LIU Hong-Gang WU De-Xin microwave device and ic department Institute of MicroelectronicsChinese Academy of SciencesBeijing 100029

Heterogeneous integration of crystalline Ge layers on cleaned and H-terminated Si(111)substrates are demonstrated by employing a combination of e-beam evaporation and solid phase epitaxy ***-quality single crystalline Ge(111)layers on Si(111)substrates with a smooth Ge surface and an abrupt interface between Ge and Si are *** XRD rocking curve scan of the Ge(111)diffraction peak shovs a FWHM of only 260 arcsec for a 50-nm-thick Ge layer annealed at 600℃with a ramp-up rate of 20℃/s and a holding time of 1 *** AFM images exhibit that the rms surface roughness of all the crystalline Ge layers are less than 2.1 nm.

关键词： crystalline Solid roughness

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Charge trapping behavior and its origin in Al_2O_3/Sic MIS system

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Chinese Physics B 2015年第8期24卷 523-528页

作者：刘新宇王弋宇彭朝阳李诚瞻吴佳白云汤益丹刘可安申华军 microwave device and ic department Institute of Microelectronics Chinese Academy of Sciences Zhuzhou CSR Times Electric Co. Ltd

Charge trapping behavior and its origin in Al2O3/Sic MOS structure are investigated by analyzing the capacitance–voltage(C–V) hysteresis and the chemical composition of the interface. The C–V hysteresis is measured as a function of oxide thickness series for an Al2O3/Sic MIS capacitor. The distribution of the trapped charges, extracted from the C–V curves, is found to mainly follow a sheet charge model rather than a bulk charge model. Therefore, the electron injection phenomenon is evaluated by using linear fitting. It is found that most of the trapped charges are not distributed exactly at the interface but are located in the bulk of the Al2O3 layers, especially close to the border. Furthermore, there is no detectable oxide interface layer in the x-ray photoelectron spectroscope(XPS) and transmission electron microscope(TEM)measurements. In addition, Rutherford back scattering(RBS) analysis shows that the width of the Al2O3/Sic interface is less than 1 nm. It could be concluded that the charge trapping sites in Al2O3/Sic structure might mainly originate from the border traps in Al2O3 film rather than the interface traps in the interfacial transition layer.

关键词： Al2O3 Si C charge trapping sites interface

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A nano-plasmonic HMIM waveguide based concurrent dual-band BPF using circular ring resonator

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Optoelectronics Letters 2024年第3期20卷 152-156页

作者： Miriyala Sridhar Surendra Kumar Bitra TS N Murthy Koppireddi Padmaraju department of Electronics and Communication Engineering Koneru Lakshmaiah Education FoundationGunturIndia Astra microwave Products Ltd. HyderabadIndia department of Electronics and Communication Engineering JNTU-GV College of EngineeringVizianagaramIndia department of Electronics and Communication Engineering Jawaharlal Nehru Technological University KakinadaKakinadaIndia

This article analyzes the transmission line characteristics of plasmonic hybrid metal insulator metal(HMIM) wave-guide, circular ring resonator(CRR) based dual-band band-pass filters with two transmission poles in both pass-bands in the optical regime using coupled line feed. The transmission line characteristics of an HMIM waveguide, such as characteristic impedance(Z_(PV)), effective refractive index(n_(eff)) and propagation length(L_(spp)), have been obtained by using full wave simulation.

关键词： waveguide resonator circular

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Finite element analysis and experimental validation of polymer-metal contacts in block-on-ring configuration

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Friction 2024年第3期12卷 554-568页

作者： K.Y.Eayal AWWAD Khosro FALLAHNEZHAD B.F.YOUSIF Ahmad MOSTAFA Omar ALAJARMEH A.SHALWAN Xuesen ZENG Mechanical Engineering department Faculty of EngineeringTafila Technical UniversityTafila 66110Jordan Medical device Research Institute College of Science and EngineeringFlinders UniversitySouth Australia 5042Australia Centre for Future Materials University of Southern QueenslandToowoomba 4350Australia department of Manufacturing Engineering Technology Public Authority for Applied Education and TrainingKuwait 13092Kuwait

The wear profile analysis,obtained by different tribometers,is essential to characterise the wear ***,most of the available methods did not take the stress distribution over the wear profile in consideration,which causes inaccurate *** this study,the wear profile of polymer–metal contact,obtained by block-on-ring configuration under dry sliding conditions,was analysed using finite element modelling(FEM)and experimental ***’s wear equation was integrated into a developed FORTRAN-UMESHMOTION code linked with Abaqus software.A varying wear coefficient(k)values covering both running-in and steady state regions,and a range of applied loads involving both mild and severe wear regions were measured and implemented in the *** FEM was in good agreement with the *** model reproduced the stress distribution profiles under variable testing conditions,while their values were affected by the sliding direction and maximum wear depth(hmax).The largest area of the wear profile,exposed to the average contact stresses,is defined as the normal *** the critical zones were characterized by high stress concentrations reaching up to 10 times of that at the normal *** wear profile was mapped to identify the critical zone where the stress concentration is the key point in this *** surface features were examined in different regions using scanning electron microscope(SEM).Ultimately,SEM analysis showed severer damage features in the critical zone than that in the normal zone as proven by ***,the literature data presented and considered the wear features the same at any point of the wear *** this study,the normal zone was determined at a stress value of about 0.5 MPa,whereas the critical zone was at about 5.5 *** wear behaviour of these two zones showed totally different features from one another.

关键词： polymer-to-metal contact block-on-ring wear profile wear model

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