Based on the differences between time-domained and frequency-domained methods, this article proposes an combined testing method for DLF of non self-supporting materials by using Oberst beam method. That is, at low frequencies or small damping frequency points, use composite beam, which is obtained from method, to replace results then loss factor can be calculated. And it was applied test a certain rubber material, successfully obtaining four modal points.

The sound quality and comfort inside civil aircraft cabins have gradually become a key factor affecting their market competitiveness. Optimizing the cabin noise environment improving are of great significance. This article is based on simulated three-dimensional field an engineering prototype, selecting eight seats using grade scoring method to conduct subjective evaluation tests certain type test under six operating conditions, including ground taxiing, takeoff, cruising, so on. After...

This study aimed to investigate the impact of tibial anatomical structure, age, sex, average weekly exercise time during adolescence (AWETA), and BMI on risk stress fractures (SF) develop a predictive model using logistic regression. We retrospectively analyzed 748 patients presenting with calf pain at our hospital from January 1, 2018, August 31, 2023. After applying inclusion exclusion criteria, 493 were categorized into SF group (295 cases) control (198 cases). Detailed patient...

We propose and experimentally demonstrate a parity-time (PT)-symmetric frequency-tunable optoelectronic oscillator (OEO) in which the PT symmetry is implemented based on single dual-polarization optical loop. By employing inherent birefringence of z-cut lithium niobate (LiNbO3) phase modulator (PM), two mutually coupled loops supporting orthogonally polarized light waves with one experiencing gain other loss are implemented. controlling gain, loss, coupling coefficients between loops,...

Abstract The Environmental Control System’s working conditions are complex, and the regulation control challenging. Moreover, bleed air system has characteristics such as large thermal inertia, high nonlinearity, strong coupling between supply systems, making it difficult to design verify its dynamic characteristics. This study aims evaluate structure of source facility in aircraft ECS laboratory meet performance requirements engine air. Through coordinated operation various components,...

A widely frequency-tunable parity-time (PT) symmetric optoelectronic oscillator (OEO) implemented based on a single polarization-dependent Sagnac loop is proposed and experimentally demonstrated. Two mutually coupled feedback loops having an identical geometry with balanced gain loss are to achieve PT-symmetry, which essential for single-mode selection without using ultra-narrow passband microwave filter. In the implementation, consisting of polarization beam splitter (PBS) two controllers...

An approach to transmitting two independent microwave vector signals on a single optical carrier with one polarization state based coherent detection and digital phase noise cancellation is proposed experimentally demonstrated. At the transmitter, are modulated an via dual-drive Mach-Zehnder modulator (DD-MZM). The transmitted over single-mode fiber (SMF) sent receiver. receiver, detected where local oscillator (LO) wave generated by second free-running laser source also applied. To recover...

A comprehensive model is presented to study the electrical, thermal, and optical behavior of broad-area traveling-wave InGaAs-AlGaAs semiconductor amplifiers. Finite-element thermal analysis carrier transport mechanisms are integrated into beam propagation method include lensing optically induced nonlinearities. self-consistent iteration developed simulate filamentation in amplifiers with residual facet reflectivities. The experimentally observed periodic intensity minima close zero...

A wavelength-tunable single-longitudinal-mode fiber ring laser based on parity-time (PT) symmetry for mode selection is proposed and experimentally demonstrated. The PT implemented using a single physical fiber-optic loop, which functions equivalently to two mutually coupled optical loops with an identical geometry but balanced gain loss. In the system, linearly polarized light wave split into two, are traveling in Sagnac loop incorporating polarization beam splitter (PBS) controllers (PCs)....

A microwave photonic link to transmit four independent vector signals modulated on a single optical carrier based coherent detection and digital signal processing (DSP) is proposed experimentally demonstrated. At the transmitter, continuous-wave (CW) light wave by with an identical center frequency at dual-polarization dual-drive Mach-Zehnder modulator (DP-DDMZM), generate intensity-modulated signals, two sharing one of orthogonal polarization states. After transmission over single-mode...

Ventilation systems for aircraft cabins are mainly used to maintain a comfortable environment in the cabin and ensure health of passengers. This study evaluates decontamination performance two ventilation systems, displacement (DV) system mixing (MV) system, preventing contamination by virus (COVID-19)-laden droplets. The Euler-Lagrange method was computationally model droplet dispersion different diameters their behavior contrastively analyzed. Statistics on suspension ratios duration as...

By exploring the relationship between gain/loss and coupling coefficient, parity-time (PT) symmetry has been well explored in photonics optoelectronics fields to achieve unique functions, such as sidemode suppression, non-reciprocal light propagation, unidirectional invisibility. In general, a PT-symmetric system an architecture with two identical coupled resonators or loops. this Letter, we explore possibility of implementing having one resonator loop length that is rational number times...

Non-Hermitian photonics based on parity-time (PT) symmetry has been considered an effective solution to achieve mode selection for optical or microwave single-mode oscillation. A PT-symmetric system is usually implemented using two mutually coupled elements with identical geometry a single element precise longitudinal refractive index modulation. In this study, we propose novel scheme PT polarization manipulation in loop. By controlling the states of light waves that are propagating along...

This paper presents a sensorless direct torque control (DTC) propulsion method of 1/2-scale controlled-PM linear synchronous motor (LSM) Maglev model vehicle which is not levitated and used as PM LSM supported by the wheel. first experiment for DTC to be applied without position speed sensors, one most important problem solved in practical applications. can directly thrust force stator flux linkage switching commands six inverter-arms with table. The DC voltage three phase current are...

A microwave photonic link (MPL) with quadrupled capacity based on coherent detection and digital phase noise cancellation is proposed experimentally demonstrated. At the transmitter, a continuous-wave (CW) light wave intensity modulated by four independent vector signals two having an identical center frequency at dual-parallel Mach-Zehnder modulator (DPMZM) consisting of dual-drive MZMs (DEMZMs) sub-DEMEMs biased quadrature transmission point. Four intensity-modulated optical are generated...

While high-powered broad area lasers emitting between 915nm and 975nm are required for pumping Er⁺ Yb⁺ doped dual clad fiber amplifiers, the single mode 980nm used EDFAs. We report on performance a systematic reliability assessment of Alfalight's first generation Al-free multimode laser diodes with 100µm aperture 2mm cavity length 950nm 980nm. Data from 120 devices in five different multi-cell conditions show median life due to wear-out failure be over 75.5 years. In...

A wavelength-space parity-time (PT) symmetric optoelectronic oscillator (OEO) with the gain/loss balance implemented using a chirped fiber Bragg grating (CFBG) is proposed and experimentally demonstrated. In OEO, two optical carriers at different wavelengths are employed to form coupled OEO loops, one wavelength reflected from top of CFBG refection spectrum other slope spectrum, thus making loop have gain loss. Once loss coefficients matched coefficient greater than coupling coefficient, PT...

This paper proposes a novel DC-AC converter topology for fuel cells. provides pulsed voltage to PWM inverter directly. As the results, it will be possible reduce size of this component because no need smoothing circuit between boost and inverter. Furthermore, is expected achieve ZVS switches has certainly zero period in switching period. analyzes called Pulse-link And shown advantage by experimental results.