The vortex electromagnetic (EM) wave, which carries orbital angular momentum (OAM), may provide extra rotational degree of freedom and can potentially be exploited in microwave staring imaging. Based on the concentric uniform circular array, generation method OAM beams for EM imaging is studied. array radius excitation signal each ring are carefully designed to ensure that main lobes with different topological charges simultaneously illuminate area where target exist. Subsequently, model...

Helical phase fronts and orbital angular momentum of the vortex electromagnetic (EM) wave are applied to radar imaging at microwave frequencies comprehensive simulations conducted. Results demonstrate that an incrementally phased uniform circular array can be exploited generate EM frequencies. The model based on linear frequency modulation signal is established pulse‐compression fast Fourier transform methods used image target in both range azimuth dimensions. Furthermore, antenna pattern...

In recent years, the orbital angular momentum (OAM) has been widely applied in target detection and imaging to improve performance of conventional radar systems. A passive OAM-based method is studied this letter. Compared with active approaches, proposed can reduce complexity transmitting system achieve azimuthal profile even small elevation angle. The model deduced single-in-multiple-out mode, algorithm based on back projection reconstruct targets. Theoretical simulation results demonstrate...

Considering the tractability of OGM (Occupancy Grid Map) and its wide use in dynamic environment representation mobile robotics, extraction motion information from successive OGMs are very important for many tasks, such as SLAM (Simultaneously Localization And Mapping) DATMO (Detection Tracking Moving Object). In this paper, we propose a novel method based on signal transform, called S-KST (Spatial Keystone Transform), detection estimation noisy OGMs. It extends KST radar imaging or...

The vortex electromagnetic (EM) wave, which carries orbital angular momentum (OAM), is exploited to multitarget detection applications. model in the squint mode derived first. elevation and azimuth angles of targets are estimated by fast Fourier transform method validated simulation. Subsequently, proof-of-concept experiments performed validate principle proposed OAM-based target technique. signal processing for real-world data obtained from identify positions targets. Experimental results...

The electromagnetic (EM) wave carrying orbital angular momentum (OAM) is usually named vortex EM wave, which has been found great potential to improve the target imaging performance. For conventional ISAR imaging, only 2-D image can be obtained. In this paper, OAM-based technique developed achieve 3-D with high resolution at terahertz frequencies. First, model derived, and point spread function analyzed. Subsequently, two algorithms, namely FFT-based method based on convolution...

Terahertz (THz) arrays can be used to improve the data acquisition speed considerably in real-time imaging applications. However, THz array usually suffers from side-lobe artifacts, which leads a severe decline image quality. In this paper, suppression method based on coherence factor is proposed The influences of signal-to-noise ratio results are analyzed by simulation. Furthermore, real-world validate effectiveness method, indicates that suppressed 29 dB. This paper benefit development...

A novel 3-D surface imaging method based on terahertz (THz) dual-frequency interferometry is proposed for the detection and of metal objects. The interferometer formed first in range direction with two azimuth–elevation images at different THz frequencies. Then, image can be obtained by interference processing results. Compared traditional wideband imaging, avoid nonlinear error caused signal nonlinearity. In addition, registration evitable, when frequency difference satisfies certain...

Quantum radar cross section (QRCS) is studied in this paper, which has an objective measure of the quantum scattering ability a specified target. The interaction process between and target introduced, new results about characteristics typical targets are reported. Simulation demonstrate that number side lobes QRCS dependent on size interatomic distance; values increase with increasing signal photon frequency. For cylinder target, increased as radius increases. work can be beneficial to...

The nonlinearity of signal usually leads to the range profile blurring and defocusing in terahertz (THz) radar ranging, which should be compensated achieve a well-focused profile. In this letter, an effective nonlinear phase compensation method is proposed compensate for distortion caused by waveform nonlinearities. It comprises two processing steps, namely, coarse precise compensation, are based on time-frequency distribution gradient autofocus algorithm, respectively. nonparametric can...

Understanding tumor clonality is critical to understanding the mechanisms involved in tumorigenesis and disease progression. In addition, clonal composition changes that occur within a response certain micro-environment or treatments may lead design of more sophisticated effective approaches eradicate cells. However, tracking sub-populations has been challenging due lack distinguishable markers. To address this problem, VDJ-seq protocol was created trace evolution patterns diffuse large B...

For fast and standoff personal screening, a novel terahertz imaging scheme using sparse rotating array is developed in this paper. A linearly designed to move along circular path with respect an axis perpendicular the scenario. new scheme, modified algorithm proposed based on frequency-domain reconstruction method synthetic aperture radar. To achieve better performance, optimization of also proposed, according distribution spectral support. Theoretical numerical analysis point spread...

Terahertz imaging has been shown to have the potential detect objects hidden under common coverings. In this paper, a 360° fast rotating scheme for detection of concealed using terahertz radar is proposed and validated by proof-of-concept experiments. The results three dangerous objects, i.e. hammer, scissor metal handgun model, covered with fabric cardboard are obtained, which demonstrate effectiveness object high resolution. work can benefit development real-time applications radar.

Raw signal simulation is an important tool to test the effectiveness of system parameters and imaging algorithms. A fast raw method for multi-circular synthetic aperture proposed based on inverse processing algorithm nonuniform Fourier transform. The analytical description procedure are presented. Simulation results ideal point target a human model demonstrate validity effectiveness. Compared with common time-domain method, can achieve equivalent performance higher efficiency.

In this paper, a uniform circular array (UCA) is exploited to generate vortex electromagnetic (EM) beam, which carries orbital angular momentum (OAM). The basic generation method of OAM-carrying beam presented firstly. Subsequently, the mathematical model with error contribution established and comprehensively numerical experiments are conducted analyze how amplitude phase errors affect intensity phase-front distributions radiation field. Results demonstrate that can lead fluctuations in...

The random phase errors existing in the terahertz (THz) radar system, usually lead to range profile broadened and defocused, which should be compensated. In this paper, a compensation method based on Bayesian compressive sensing (BCS) is proposed. Firstly, reconstruction model containing established. Subsequently, obtained using maximum likelihood estimation, then, echo compensated with time domain focus profile. Experimental results simulation data demonstrated that proposed can produce...

A terahertz (THz) radar system with the highest frequency up to 0.22THz is described in this paper. The built based on microwave up-conversion technology and a good performance operating range. cross section (RCS) measurement of different objects, namely, corner reflector, cylinder, rectangular plate scale car model, performed THz system. By comparison results plates surface characterization, conclusion reached that detailed has considerable influence RCS values. Moreover, values model...

The evaluation of the focal field Cassegrain antennas is crucial for design and optimization complex feeds in quasi-optical systems. However, employing traditional physical optics methods generates high computational complexity inefficient. An accurate efficient calculation method antennas’ fields that involves a range incidence angles proposed, which integrates ray tracing vector diffraction integration (RT-VDI) theories. It can calculate any given or predefined incident direction, not...

Yiyi decoction is a Chinese herbal formula for the treatment of acute pancreatitis that has been used in clinical practice decades. A previous study suggested resveratrol, emodin, rhein and their derivatives might be potential pharmacodynamic components decoction, researchers have proposed emodin are candidate markers quality control. The present investigated intervention effect its effective on murine using metabolomic approach integrated global unique metabolic characteristics. First,...

Recently, much attention has been focused on the vortex electromagnetic (EM) beam, which carries orbital angular momentum (OAM), at radio and radar frequencies. In this paper, radiation pattern synthesis methods for generation of EM beam based uniform circular array (UCA) are proposed. Directional elements concentric-ring arrays effectively exploited to optimize as sparse, especially suppression side lobes grating lobes. The work can benefit OAM-carrying beams its applications in...

A novel terahertz (THz) three-dimensional (3D) imaging scheme based on the multi-circular synthetic aperture is studied in this paper. The integral sidelobe ratio and resolution discussed as a function of signal bandwidth, number circular path. simulated point spread demonstrates 3D capability scheme. array technique can significantly improve performance.

The electromagnetic (EM) vortex imaging method based on the distributed OAM radiation sources are studied, for first time. orthogonality of eigenmodes enables that reconstruction targets with limited measurements. Firstly, model is derived and established. Subsequently, sparse Bayesian learning (SBL) framework introduced to reconstruct target image. Simulations conducted validate effectiveness proposed analyze influences noise performance. This work can as a reference design DAM-generation...

Multiplexing samples in sequencing experiments is a common approach to maximize information yield while minimizing cost. In most cases the number of that are multiplexed determined by financial consideration or experimental convenience, with limited understanding on effects results. Here we set examine impact multiplexing ChIP-seq ability identify specific epigenetic modification. We performed peak detection analyses determine multiplexing. These include false discovery rates, size, position...