Experimental realization of a broadband illusion optics device

We experimentally demonstrate the first metamaterial "illusion optics" device - an "invisible gateway" by using a transmission-line medium. The device contains an open channel that can block electromagnetic waves at a particular frequency range. We also demonstrate that such a device can work in a broad frequency range.Comment: 9 pages, 5 figure

Real-space sampling of terahertz waveforms with sub-nanometer spatial resolution

Terahertz scanning tunneling microscopy (THz-STM) has emerged as a potent technique for probing ultrafast nanoscale dynamics with exceptional spatiotemporal precision, whereby the acquisition of THz near-field waveforms holds paramount significance. While substantial efforts have been dedicated to retrieving the waveform utilizing the photoemission current or a molecular sensor, these methods are challenged by intensive thermal effects or complex sample preparations. In this study, we introduce a universal approach for real-time characterization of THz near-field waveforms within the tunnel junction, achieving sub-nanometer spatial resolution. Utilizing the gating mechanism intrinsic to the STM junction, coherent scanning of a gated strong THz pulse over a weak THz pulse is achieved, facilitating direct measurement of the waveform. Notably, employing a custom-built Carrier-Envelope Phase (CEP) shifter, THz-CEP has been successfully characterized in the tunnel junction. Furthermore, THz spectral imaging through point-to-point sampling of THz waveforms on a triatomic Au (111) step has been demonstrated, highlighting the sub-nanometer spatial resolution of our sampling methodology.Comment: 26 pages and 4 figures for the manuscript; 16 pages and 7 figures for the Supporting Informatio

Experimental validation of a quasi-realtime human respiration detection method via UWB radar

In this paper, we propose a quasi-realtime human respiration detection method via UWB radar system in through-wall or similar condition. With respect to the previous proposed automatic detection method, the new proposed method assures competitive performance in the human respiration motion detection and effective noise/clutter rejection, which have been proved by experimental results in actual scenario. This new method has also been implemented in a UWB through-wall life-detection radar prototype, and its time consuming is about 2 s, which can satisfy the practical requirement of quasi-realtime for through-wall sequential vital sign detection. Therefore, it can be an alternative for through-obstacles static human detection in antiterrorism or rescue scenarios

Neural Conversation Generation with Auxiliary Emotional Supervised Models

An important aspect of developing dialogue agents involves endowing a conversation system with emotion perception and interaction. Most existing emotion dialogue models lack the adaptability and extensibility of different scenes because of their limitation to require a specified emotion category or their reliance on a fixed emotional dictionary. To overcome these limitations, we propose a neural conversation generation with auxiliary emotional supervised model (nCG-ESM) comprising a sequence-to-sequence (Seq2Seq) generation model and an emotional classifier used as an auxiliary model. The emotional classifier was trained to predict the emotion distributions of the dialogues, which were then used as emotion supervised signals to guide the generation model to generate diverse emotional responses. The proposed nCG-ESM is flexible enough to generate responses with emotional diversity, including specified or unspecified emotions, which can be adapted and extended to different scenarios. We conducted extensive experiments on the popular dataset of Weibo post--response pairs. Experimental results showed that the proposed model was capable of producing more diverse, appropriate, and emotionally rich responses, yielding substantial gains in diversity scores and human evaluations.Peer reviewe

Surface Permittivity Estimation of Southern Utopia Planitia by High-Frequency RoPeR in Tianwen-1 Mars Exploration

China’s Tianwen-1 successfully landed in the southern Utopian Planitia of the Martian surface on 15 May 2021. The Zhurong Rover, equipped with a high-frequency full polarimetric Rover Penetrating Radar (RoPeR), traveled 1921 m to investigate the shallow geological structure and material composition of the Martian weathered layer. In this study, we propose a new processing strategy to estimate surface relative permittivity using the HH and VV reflections of the high-frequency RoPeR data. This new strategy is based on the induced field rotation (IFR) effect, which occurs when orthogonally polarized electromagnetic (EM) waves propagate into an uneven surface with incident angles. Three-dimensional time-domain finite-difference simulations were performed using random surfaces with various relative permittivities under the same geometry as the Zhurong Rover. Polarimetric alpha angle versus relative permittivity was then calculated based on the simulation results. At the same time, direct coupling (DC) removal, bandpass filtering, and channel calibration were performed on the real RoPeR data, and clear surface reflections were extracted. The surface reflection amplitudes of the HH and VV were then obtained and the polarimetric alpha angle was calculated. Finally, relative permittivity was estimated through the relationship obtained from the simulation results. The average value of the relative permittivity estimated by the proposed approach is 3.292, with a standard deviation of 0.235. This result is consistent with that obtained by orbiting radar systems and the low-frequency RoPeR system. This study will contribute to the further signal processing and accurate interpretation of real radar data captured by way of RoPeR on Mars

Human Respiration Localization Method Using UWB Linear Antenna Array

Human respiration is the basic vital sign in remote monitoring. There has been remarkable progress in this area, but some challenges still remain to obtain the angle-of-arrival (AOA) and distinguish the individual signals. This paper presents a 2D noncontact human respiration localization method using Ultra-Wideband (UWB) 1D linear antenna array. The imaging reconstruction based on beamforming is used to estimate the AOA of the human chest. The distance-slow time 2D matrix at the estimated AOA is processed to obtain the distance and respiration frequency of the vital sign. The proposed method can be used to isolate signals from individual targets when more than one human object is located in the surveillance space. The feasibility of the proposed method is demonstrated via the simulation and experiment results

An FPGA-Integrated Time-to-Digital Converter Based on a Ring Oscillator for Programmable Delay Line Resolution Measurement

We describe the architecture of a time-to-digital converter (TDC), specially intended to measure the delay resolution of a programmable delay line (PDL). The configuration, which consists of a ring oscillator, a frequency divider (FD), and a period measurement circuit (PMC), is implemented in a field programmable gate array (FPGA) device. The ring oscillator realized in loop containing a PDL and a look-up table (LUT) generates periodic oscillatory pulses. The FD amplifies the oscillatory period from nanosecond range to microsecond range. The time-to-digital conversion is based on counting the number of clock cycles between two consecutive pulses of the FD by the PMC. Experiments have been conducted to verify the performance of the TDC. The achieved relative errors for four PDLs are within 0.50%-1.21% and the TDC has an equivalent resolution of about 0.4 ps

Change in perioperative neutrophil-lymphocyte ratio as a potential predictive biomarker for chronic postsurgical pain and quality of life: an ambispective observational cohort study

IntroductionAccurate and accessible predictors of chronic postsurgical pain (CPSP) to identify high-risk postsurgical patients are prerequisite for preventive and interventional strategies. We investigated the incidence and risk factors of CPSP after abdominal surgery, with a focus on plasma immunological markers.Materials and methodsThis was a retrospective analysis of patients who underwent abdominal surgery under general anesthesia at a tertiary center between January 2021 and January 2022. The preoperative demographics, laboratory test data, and surgical factors of the participants were collected from the electronic medical record system. Postoperative pain intensity and living conditions at 1 year after discharge from the hospital were assessed via a phone survey. Univariate and multivariate analyses were used to explore independent risk factors associated with CPSP.ResultsA total of 968 patients were included, and 13.53% (n = 131 of 968) of patients reported CPSP 1 year after surgery. Patients with older age, open surgery, higher American Association of Anesthesiologists classification, patient-controlled intravenous analgesia application, longer surgery duration, higher postoperative absolute neutrophil count, and neutrophil-lymphocyte ratio (NLR), lower postoperative absolute lymphocyte count, and higher white blood cell count, were more likely to suffer from CPSP. A changed ratio of NLR (postoperative to preoperative) ≥ 5 significantly correlated with CPSP, moderate to severe pain, maximum numeric rating score since discharge from the hospital, and affected quality of life.DiscussionThe changed ratio of NLR could be used for the early identification of patients at risk for CPSP and affect the quality of life to alert the clinician to undertake further assessment

Analysis of GPR Antenna System Above Ground

We demonstrate an analysis of a ground penetrating radar (GPR) antenna system by using Wavenology EM, which is an efficient electromagnetic wave simulator. The system includes three identical half ellipse antennas: one is used for transmission, and the other two are for reception. Our investigations show that the antenna system has good radiation characteristics both in frequency and time domain. Furthermore,  the ground effects on the antenna performance are taken into account by the FDTD method using adaptive mesh