Abstract Real-Time Kinematic Precise Point Positioning (PPP–RTK) is inextricably linked to external ionospheric information. The PPP–RTK performances vary much with the accuracy of information, which derived from different network scales, given prior variances, and obtained under disturbed conditions. This study investigates relationships between performances, in terms precision convergence time, statistical results show that Time First Fix (TTFF) for constrained by Global Ionosphere Map...

A need exists for a robust flow control actuator that is capable of penetrating supersonic boundary layers. Under Air Force Office Scientific Research sponsorship, The Johns Hopkins University Applied Physics Laboratory investigating promising device high-speed called the SparkJet actuator. This actuator, which produces synthetic jet with high exhaust velocities, holds promise manipulating flows without active mechanical components. Computational and experimental techniques are being used to...

Computational and experimental techniques are being used to investigate the operating characteristics of a promising cavity device for high-speed flow control called SparkJet actuator. This actuator, which produces synthetic jet with high exhaust velocities, holds promise manipulating supersonic boundary layers without active mechanical components. paper focuses on characterization newly-redesigned SparkJet. Numerical parametric studies previous design characterized performance attributes as...

This work is focused on the active vibration control of piezoelectric cantilever beam, where an adaptive feedforward controller (AFC) utilized to reject with unknown multiple frequencies. First, experiment setup and its mathematical model are introduced. Due that channel between disturbance output in practice, a concept equivalent input (EID) employed put into channel. In this situation, can be achieved by setting identified EID. Then, for EID known frequencies, AFC introduced perfectly but...

ABSTRACT A large eddy simulation was performed on an National Renewable Energy Laboratory (NREL) phase VI wind turbine (10 m diameter), using the exact blade geometry, to determine influence of different inflow conditions aerodynamic loadings and near wake characteristics. The effects three conditions, uniform inflow, linear shear with turbulence, are investigated. Wind causes periodic variations in power loading additional force component exerted along lateral direction. Significant...

This paper presents an effective metric to evaluate different kinds of low probability interception (LPI) waveforms. Based on the common view that white noise is best LPI waveform, method introduced in this first use asymptotic spectral distribution Wigner matrix as property and normalized sample covariance a specific waveform. Then, numerical approximation Kullback-Leibler divergence (NA-KLD) deduced measure distance between two distributions. The NA-KLD regarded metrication A lower value...

The highly dynamic properties of maneuvering targets make it intractable for radars to predict the target motion states accurately and quickly, low-grade predicted depreciate efficiency resource allocation. To overcome this problem, we introduce modified current statistical (MCS) model, which incorporates input-acceleration transition matrix into augmented state matrix, a target. Based on this, robust allocation strategy is developed tracking (MTT) in netted opportunistic array radar (OAR)...

Abstract This paper investigates the attitude control problem of morphing vehicle subject to great dynamics changes and disturbances during phase. An improved model‐free adaptive (MFAC) method is proposed based on compact format dynamic linearization technique. Firstly, a data model data‐driven scheme are established input/output (I/O) controlled plant, independent complicated time‐varying mathematical vehicle. Secondly, series historical output errors in moving time window introduced law,...

Abstract Environmental wind measurements are essential for ensuring the operational safety of rail vehicles. In our previous work, an anemometer that can be mounted on top a train to achieve real-time speed and direction was proposed based pressure distributions around cylindrical anemometer. However, flow field is significantly influenced by train; thus, measured data might differ from actual environmental parameters, particularly when trains subjected windbreak walls. this study,...

This paper investigates the problem of optimal power allocation for radar network to improve system low probability intercept (LPI) performance. We first introduce signal model, and derive Schleher factor network. Then, with defined target threatening level, two algorithms are proposed. The one is optimize transmitting a predefined mutual information (MI) threshold, second find given minimum mean-square error (MMSE) threshold. There one-to-one correspondence between level MI/MMSE we need...

Finding a balance between observation duration and detection rates is the ultimate goal of ultra high speed targets.However, short durations, both across range unit (ARU) Doppler frequency migration (DFM), may severely limit performance targets.Although traditional coherent integration methods can efficiently accumulate signal energy to produce noise ratio (SNR) measurement, they often need search for unknown motion parameters.This timeconsuming unacceptable real-time targets.In this paper,...

This paper proposes a radar radiation control method based on cooperation tracking of multiple sensors. The main idea the is passive in platforms used preferentially, while tracks target timely according to accuracy. In this paper, accuracy metric called interactive model predicted covariance (IMMPC) derived by IMM-EKF algorithm. By comparing with pre-defined threshold, whether or not transmitter radiates energy determined. Simulation results show that proposed can reduce times effectively...

Low probability of intercept (LPI) radar signal design is a very important issue on modern battlefield. Different phase coding technologies are used to modulate Costas frequency hop sequence, and five kinds continuous wave signals including Costas, Costas_qbarker, Costas_frank16, Costas_px16 Costas_zadoff-chu13 proposed designed in this paper. The target resolution LPI performance the Costas/PSK analysed compared. ambiguity function power spectral densities (PSDs) different also simulated...

This paper proposes a new Asian single site tropospheric correction model called the Single Site Improved European Geostationary Navigation Overlay Service (SSIEGNOS) by refining (EGNOS) at site. The performance of SSIEGNOS is analyzed. results show that (1) bias and root mean square (RMS) error zenith delay (ZTD) calculated from EGNOS are 0.12 cm 5.87 cm, respectively; whereas those 0 2.52 respectively. (2) RMS seasonal variation in model; however, little observed model. (3) decreases with...

In this paper, a novel low-order blade element momentum model, called flux-line theory, is developed for predicting the performance of cycloturbines (variable-pitch vertical-axis wind turbines). It improves upon prior theories by capturing flow expansion/contraction and bending through turbine. This accomplished performing fluid calculations in coordinate system fixed to streamlines which spatial locations are not predescribed. A transformation determines Cartesian location rotor disk,...

This paper provides a novel methodology for removing sensor bias from space based infrared (IR) system (SBIRS) through the use of stars detected in background field sensor. Space IR uses LOS (line sight) target location. determination and calibration is key precondition accurate location tracking targets scanning one difficulties. The subsequent changes are not been taking into account conventional process. Based on analysis imaging process sensor, theoretical model estimation angles using...

With the development of airborne radar radio frequency stealth (RFS) technology, method improving RFS performance by optimizing target detection has been extensively studied. However, for wideband signals, traditional point model appears as an extended in range-dimension, which is unfavorable to echoes. To overcome existing drawbacks, this paper devises efficient echo algorithm from perspective information theory and random matrix. Firstly, aperiodic agile signals are utilized observe...