We present a polarization sensitive terahertz detection method which is able to measure both orthogonal components of the electric field. It allows for study dependent properties materials. Azimuthal angle transmittance in 0.2–2.6 THz frequency region crystalline quartz measured. Polarized transmission spectroscopy shows that birefringence can result minima. This work suggests effective removing fake absorption features caused by material birefringence.

In this paper, an approach to improve the disturbance suppression performance of a fast steering mirror (FSM) tracking control system based on charge-coupled device (CCD) and micro-electro-mechanical (MEMS) inertial sensors is proposed. The observation compensation (DOC) method recommended enhance classical multi-loop feedback (MFC) for line-of-sight (LOS) stabilization in FSM system. MEMS accelerometers gyroscopes have been used tentatively implement MFC instead fiber-optic (FOG) because...

The electro-optical tracking system with speedability and maneuverability based on stationary platform is confronted some problems such as external physical disturbance detector delay. To obtain better stability, which the key to achieving high precision, a modified Smith predictor method for inertia stabilization loop control introduced. This proposes scheme compensate delay time caused by signal filtering of fiber gyroscope sensor in velocity feedback control, it utilizes feedforward...

With the rapid advancement of Large Language Models (LLMs), safety LLMs has been a critical concern requiring precise assessment. Current benchmarks primarily concentrate on single-turn dialogues or single jailbreak attack method to assess safety. Additionally, these have not taken into account LLM's capability identifying and handling unsafe information in detail. To address issues, we propose fine-grained benchmark SafeDialBench for evaluating across various attacks multi-turn dialogues....

In this paper, a modified disturbance observer (DOB) for fast steering mirror (FSM) optical system based on charge-coupled device (CCD) and inertial sensors is proposed. Combining DOB with the classical cascaded multiloop feedback control, including position loop, velocity acceleration that suppression performance of line-of-sight in an FSM can be significant improved. However, due to quadratic differential open-loop response, fact, it very difficult realize integral algorithm compensate...

Using the passive THz imaging system developed by CNU-THz laboratory, we capture image of human body with forbidden objects hidden under opaque clothes. We demonstrate possibility significant improving quality image. Our approach bases on application spatial filters, us for computer treatment imaging. The is constructed accordance to well known principles and quasi-optical theory. It contains a scanning mechanism, which has detector approximately 1200μm central wavelength, data acquisition...

Magneto-optical (MO) properties of bi- and tri-layer graphene are investigated utilizing terahertz time-domain spectroscopy (THz TDS) in the presence a strong magnetic field at room-temperature. In Faraday configuration applying optical polarization measurements, we measure real imaginary parts longitudinal transverse MO conductivities different samples. The obtained experimental data fits very well with classical Drude formula. Thus, able to obtain key sample material parameters graphene,...

The performance of the particle swarm is mainly influenced by individual particles experience and group in period evolution for optimization. To make full use two factors effectively improve optimization performance, Introduced a novel Two-subpopulation Particle Swarm Optimization, proportion experiences different each subpopulation swarm. If greater than experience, search space abroad, whereas, local area fully. proposed combines both advantages, more fully not easily into minimum points....

In order to realize the dive plane trajectory tracking control of AUV under current disturbance, state-dependent Riccati equation algorithm is presented. When far away from point, driving pitch angle same as line-of-sight angle, when nearby make velocity vector tangent vector. rudder saturated constraints problem, introducing hyperbolic S type function, equivalent substitution Angle variables. Through pseudo-linearization dynamic equations, and calculation Algebraic equation, nonlinear...

The charge couple device (CCD) tracking loop of a fast steering mirror (FSM) is usually used to stabilize line sight (LOS). High closed-loop bandwidth facilitates good performance. However, low-rate sample and time delay the CCD greatly limit high control bandwidth. This paper proposes an error-based observer (EBO) improve low-frequency performance system. basic idea by combining LOS error from controller output produce high-gain observer, forwarding into originally proposed EBO can system...

In the charge-coupled device (CCD) and micro-electro-mechanical system (MEMS) accelerometer based low-cost multi-loop optoelectronic control (OCS), due to accelerometers’ drift noise in low frequency, disturbance suppression (DS) is insufficient. Previously, on acceleration position dual-loop (ADLC), researchers combined a observer (DOB) with virtual velocity loop make some medium-frequency DS exchange for low-frequency performance. However, it not optimal because classic DOB...

In the CCD-based fine tracking optical system (FTOS), whole disturbance suppression ability (DSA) is product of inner loop and outer position loop. Traditionally, high sampling fiber-optic gyroscopes (FOGs) are added to platform stabilize line-of-sight (LOS). However, because FOGs' cost relatively big volume relative back narrow space small rotating mirrors, we attempt in this work utilize a cheaper smaller micro-electro-mechanical (MEMS) accelerometer build loop, replacing FOG....

In this paper, a modified disturbance observer (DOB) for fast steering mirror (FSM) optical system based on charge-coupled device (CCD) and inertial sensors is proposed. Combining DOB with the classical cascaded multi-loop feedback control (MFC), including position loop, velocity acceleration suppression performance of line-of-sight (LOS) in FSM can be significant improved. However, due to quadratic differential open-loop response, fact, it very difficult realize an integral algorithm...

In this paper, a novel Smith predictor control strategy improved by high bandwidth inner loop for fast steering mirror (FSM) tracking system based on charge-coupled device (CCD) and rate sensor is proposed. A velocity closed-loop constructed fiber-optic gyroscope utilized to provide robust controlled plant the controller. Usually, due mechanical resonances time delay induced low CCD sampling rate, performance of FSM insufficient when suffering uncertain input command. Therefore, control,...

In the optical stabilization control system (OSCS) based on a charge-coupled device (CCD), performance of line-of-sight is severely limited by mechanical resonance and low sampling rate CCD. An approach to improve OSCS with load restriction three loops, including an acceleration loop, virtual velocity position using MEMS accelerometers CCD proposed. The signal obtained accelerators instead gyro sensors. Its advantages are power, cost, small size, wide measuring range. A detailed analysis...

A plug-in module acceleration feedback control (Plug-In AFC) strategy based on the disturbance observer (DOB) principle is proposed for charge-coupled device (CCD)-based fast steering mirror (FSM) stabilization systems. In classical FSM tracking systems, dual-loop (DLC), including velocity and position feedback, usually utilized to enhance closed-loop performance. Due mechanical resonance of system CCD time delay, bandwidth severely restricted. To solve this problem, cascade (AFC), which a...

As it is well-known, passive THz imaging devices have big potential for solution of the security problem. Nevertheless, one main problems, which take place on way using these devices, consists in low image quality developed camera. To change this situation, necessary to improve engineering characteristics (resolution, sensitivity and so on) camera or use computer processing image. In our opinion, last issue more preferable because inexpensive. Below we illustrate possibility suppression...

A novel improved particle swarm algorithm named competition optimization (CPSO) is proposed to calibrate the Underwater Transponder coordinates. To improve performance of algorithm, TVAC introduced into CPSO present an extension (ECPSO). The method tested with a set 10 standard benchmark problems and results are compared those obtained through existing PSO algorithms, basic (BPSO), linear decreasing inertia weight (LWPSO), exponential (EPSO), time-varying acceleration coefficient (TVAC)....

An approach of 3D path planning for AUV on the basis virtual terrain and thread map is proposed. The constructed to predigest search space, transforming 2D planning. Then, made unification hostile threat terrain. To obtain standout expansibility, an improved A* algorithm based circle searching applied search. Simulation results illustrate proposed simple, fast, posed safe trail.

Maneuvering target prediction and tracking technology is widely used in both military civilian applications, the study of those technologies all along hotspot difficulty. In Electro-Optical acquisition-tracking-pointing system (ATP), primary traditional maneuvering targets are ballistic target, large aircraft other big targets. Those have features fast velocity a strong regular trajectory Kalman Filtering polynomial fitting good effects when they to track recent years, small unmanned aerial...

In this paper, the THz spectra of several weakly absorptive chemical materials are measured by a novel technology: reference-free transmission spectroscopy. We then introduce new spectral feature recognition method applying pattern in explosive classification and identification. Two types artificial neural networks (ANNs): self organized mapping (SOM) multilayer perceptron (MLP) used through repetitive modeling adequate training with high accuracy rate low alarm rate. The results indicate...

A prediction feedforward control based data fusion is proposed to enhance closed-loop performance in electro-optical tracking system. The aim of controller estimate the target trajectory and velocity by synthesizing line-of-sight error angular position from encoder. However, time delay existing every algorithm will still affect performance. In this paper, an orthogonal least square (OLS) method improve precision. transfer function OLS frequency domain built analyze time-delay...

THz radiation can penetrate through many nonpolar dielectric materials and be used for nondestructive/noninvasive sensing imaging of targets under nonpolar, nonmetallic covers or containers. Thus using systems to "see through" concealing barriers (i.e. packaging, corrugated cardboard, clothing) has been proposed as a new security screening method. Objects that detected by include concealed weapons, explosives, chemical agents clothing. Passive system detect wave from human body without...