High-intensity coal mining (large height, shallow depth, and rapid advancing) frequently causes large-scale ground damage within a short period of time. Understanding subsidence under high-intensity can provide basis for mining-induced assessment, land remediation in area, ecological reconstruction vulnerable regions Western China. In this study, the status Shendong Coalfield was investigated analyzed using two-pass differential interferometric synthetic aperture radar (DInSAR) technology...

The brushless excitation structure characteristics of the aviation wound-rotor synchronous starter/generator (WRSSG) put forward requirement on exciter (BE) model that both stator and rotor windings can be interfaced with external circuit directly. In this paper, a double-side variable-parameter voltage-behind-reactance (DS-VP-VBR) BE considering magnetic saturation was established firstly to realize direct connection between circuits. Then, constant-parameter VBR (DS-CP-VBR) completely...

Due to the reliability problems of mechanical position sensors, rotor estimation technology is an alternative for starting control aircraft wound-field synchronous starters/generators. Reversible saliency and high-frequency attenuation characteristics main machine (MM) may lead failure existing signal-based methods. In this article, low-frequency signal (LFS) injection a novel extraction method are combined estimate position. First, LFS injected into MM's stator winding, response containing...

Green spaces play an important role in improving the health and quality of life urban residents, environmental justice has become one most debated topics for scholars governments China. The accessibility green space been recognized as effective method assessment justice. Population are two basic elements evaluating accessibility. However, high-precision population data difficult to obtain. To address this issue, we propose a straightforward assess using artificial building investigate how...

During on-load starting process of an aviation wound-field synchronous starter/generator system, accurate rotor position information is required. Mechanical sensor susceptible to interference, increasing volume and weight, so online estimation more desirable. Harmonics main exciter (ME) caused by rotating rectifier are analyzed, the fifth harmonic used creatively estimate in this article. In method, performing coordinate transformation on stator current ME, increment extracted obtained...

A simple wideband decoupling method for monolithic multielement dielectric patch (DP) antenna (DPA) array is presented in this letter. Thanks to the multimode of DP resonator, TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">40</sub> and TE xmlns:xlink="http://www.w3.org/1999/xlink">42</sub> modes, which can be viewed as four xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> are...

Fault detection of a rotating rectifier for wound-rotor synchronous starter/generator (WRSSG) without rotor position sensor in the stationary state is necessary successful engine start. Based on high-frequency (HF) voltage injection, novel fault method WRSSG proposed. The HF imposed stator windings main machine, and feature current signal extracted exciter used detection. In this article, with under different working conditions analyzed first. To obtain response exciter, model analyzed....

Abstract In the field of electric aircraft, axial force conical motor is used to offset propeller thrust and reduce bearing wear. For problem accurate calculation no‐load motor, combined with characteristics that rotor magnetic bridge hybrid inner‐mounted permanent magnet synchronous (HC‐IPMSM) easy be saturated difficult calculated analytically, an equivalent analytical method proposed. According principle constant air‐gap flux, HC‐IPMSM many cylindrical surface‐mounted motors (CY‐SPMSM),...

Radiometric calibration is the basis of data processing for dynamic monitoring quantitative indicators using multi-temporal remote sensing images. Its purpose to eliminate differences values between sensor measured and objectives spectral reflectance or radiance. Since spectrum SPOT2/4 satellite images covers a small range, aerosol model can not be corrected by way FLAASH, therefore in this paper relative radiometric correction based on PIF after atmospheric achieved. Through sampling...

For an aviation brushless synchronous starter/ generator system, rotors of the main exciter (ME) and machine (MM) rotate synchronously. Meanwhile, abundant current harmonic in ME's rotor, which is caused by a rotating rectifier, contains rotor position information. Then, MM can be obtained indirectly signals ME. In this article, based on characteristics excitation estimated ME employed innovatively for estimation at low speed. First, winding are analyzed, low-order used increment estimation....

Accurate rotor position estimation plays an important role in the start control for aircraft three-stage Wound Rotor Synchronous Starter-Generator (WRSSG). In this paper, a novel exciter controller and method WRSSG were proposed. The consists of three-phase full-bridge converter full H-bridge converter, it is used to inject high frequency voltage into permanent magnet pre-exciter estimate starting mode, regulate field current main output machine generation mode. proposed has advantages...

At Datong coalfield, the heavy mining activities in its jurassic & carboniferous coal seams has caused very serious adverse effects to local geological environment, such as soil avalanche, landslide, mud-rock flow, surface settlement, crack, gangue stack, deformations and subsidence. Moreover, causes groundwater leakage, excessive exploitation greatly intensified settlement City. The paper uses 8 cognominal ERS-1/2 SAR data frames obtained during 1992 2003 period, 84 deformation fields. Of...

Using the main exciter (ME) as a quasi-resolver to perform sensorless starting control of brushless synchronous starter/generator (BSSG) is novel and promising strategy. The back electromotive force (EMF) ME essential information for this approach, however, which observer suitable obtain complex sawtooth EMF stays an open question. In paper, three advanced nonlinear observers, non-singular fast terminal sliding mode (NFTSMO), high gain disturbance (HGDO), order (HODO), are constructed, their...

A novel on-line rotor position estimation method for an aircraft wound-field synchronous starter/generator in the low-speed region is proposed this paper. Unlike that of High-frequency signal injection, new utilizes zero-sequence component estimation, which inherently produced by space-vector pulsewidth modulator. In way, no modification required PWM and there additional torque ripple. The based on multi-stage structure mutual inductance between stator windings main machine, so it...

The pseudo-random-frequency signal injection method helps to decrease the intensity of acoustic noise generated by high-frequency injection. When running as a motor in starting process, aviation three-stage brushless synchronous starter/generator is high overload condition and drastic change armature current will cause saliency main machine disappear or even reverse, which results failure traditional rotor position estimation based on saliency. This paper uses multistage structure mutual...

The existing rotor position estimation methods for aviation brushless synchronous starter/generator (BSSG) are with such drawbacks as the complex signal processing and phase delay caused by filters. In this paper, analyzing current characteristics of main exciter (ME), a novel method based on "fixed-point sampling rotor's direct-axis ME" used machine (MM) is proposed. implemented three steps: Firstly, direct quadrature axis currents ME calculated ME's stator voltage signals; Secondly,...

In order to reduce the impact of external disturbances on electric propulsion permanent magnet synchronous motor (PMSM) system aircraft, a model predictive control (MPC) optimization algorithm based nonlinear disturbance observer is proposed. this paper, controller firstly used calculate expected voltage vector, and added basis observe compensate caused by parameter changes environment. At same time, considering problem that effect compensation reduced due long calculation time MPC, observed...

The continuous integration of renewable energy into the grid has reduced its inertia and damping levels. When disturbances occur, is prone to frequency excursion issues, which restrict further utilization energy. Consequently, an increasing number codes require active participation sources in system’s regulation (FR). Direct-drive permanent magnet synchronous wind power systems, characterized by their simple structure high reliability, have gradually become mainstream systems. By controlling...

Due to the special structure of BSSG, rotating rectifier causes current distortion on rotor side ME, which also affects stator ME. In this paper, a real-time position estimation method based sum squares ME currents is proposed. method, extreme values and its corresponding torque are extracted used calculate speed frequency BSSG. Combined with an existing initial rotation angle MM can be fetched continuously. This requires no high-frequency signal injection, avoids dependence salient poles,...