Abstract For high-precision positioning and attitude determination of unmanned systems in marine environments such as surface vessels (USV) underwater vehicles (UUV), precise point (PPP) inertial navigation system (INS) integrated are usually recommended. The post-mission smoothing algorithms can fully utilize observations to provide optimal estimates address the limitations inherent Kalman filtering (KF) satellite signal degraded environments. We propose a new post-processing scheme...

As an essential part of the global water cycle, effective detection snow depth is great significance to study climate change. Global Navigation Satellite System Interferometric Reflectometry (GNSS-IR) technology emerged as a new ground-based monitoring method. The principle invert height reflection surface according SNR at low elevation angle. However, topographic relief in area GNSS stations often dramatically impacts accuracy inversion. This proposes Terrain Tilt Correction (TTC) algorithm...

Abstract With the aid of Doppler velocity logger (DVL), strapdown inertial navigation systems (SINSs) can provide continuous and accurate parameters for unmanned underwater vehicles (UUVs). However, owing to complex environment, partial DVL beams may fail be reflected by seafloor, resulting in measurement outage. In this study, a novel data-driven approach enhancing DVL/SINS integrated system is proposed improve robustness accuracy UUV with limited beams. First, make full use available beam,...

Abstract Despite advancements in global navigation satellite system/inertial system (GNSS/INS) integrated systems, the challenge of achieving rapid and accurate initial heading alignment remains, particularly low-grade IMUs marine applications with swaying conditions. This study introduces an innovative in-motion method utilizing time-differenced carrier phases (TDCP) from a single GNSS antenna IMU based on fundamental principle trajectory similarity. The angle is determined by comparing...

The tightly coupled global navigation satellite system (GNSS) precise point positioning (PPP) and inertial (INS) can provide high-precision position, velocity attitude information. utilizes single receiver, which is particularly suitable for the environment without reference station, such as marine survey. In former works, integer ambiguity resolution of PPP/INS in terrestrial researched. However, GNSS observation severely affected by multipath effect environment. addition, sideslip caused...

Cymbidium sinense are among the most important commercial orchids cultivated in China for flower production. In April of 2010, a leaf spot was sporadically observed on C. fields located Guangzhou, China. Symptoms first appeared as yellow to brown, irregular-shaped lesions margin or tip. As infection continued tissues, expanded and became dark brown along margins developed gray centers. At later stages, numerous epidermal acervuli mucilaginous conidial masses under moist conditions. Ten...

Integration of strapdown inertial navigation system (SINS) and doppler velocity log (DVL) is usually applied in underwater applications, wherein DVL provides the three-dimensional velocity, hence accumulated error SINS can be compensated. However, DVL/SINS loosely coupled approach fails complex environments on condition fewer than three available beams. And tightly divergences with only one direction information from beam measurement. To solve problems, a novel method proposed this paper,...

For the integrated system incorporating a low-cost inertial measurement unit (IMU) and global navigation satellite (GNSS), rapid accurate initial heading alignment is still significant challenge, especially for marine applications in challenging ocean conditions. To overcome this difficulty, we propose an in-motion coarse method using single-antenna GNSS low-grade IMU based on basic principle of trajectory similarity. The angle determined by dead reckoning (DR)-derived GNSS-derived gyro...

Abstract With satellite phase bias products, integer ambiguity resolution (AR) enabled precise point positioning (PPP) can be achieved, that is, PPP-real-time kinematic (RTK). However, PPP-AR still requires minutes to converge centimeter-level accuracy, as atmospheric delay parameters need estimated in the user un-combined (UC) model. To shorten convergence time, reference-network-derived corrections are often directly corrected for raw code/phase observables, without considering their...

Tibouchina semidecandra Cogn. is a popular ornamental plant in tropical and subtropical areas (1). In August 2011, leaf spot was observed on approximately 70% of 5,000 potted plants T. nursery Zhongshan, Guangdong Province, China. Each round with brown center surrounded by reddish border, ranged from 8 to 10 mm diameter. A fungus isolated consistently the lesions surface-sterilizing symptomatic sections (each 3 cm 2 ) 75% alcohol for s, washing sterile water, soaking 3% NaOCl 15 rinsing...

AbstractAbstractPrecise position of Unmanned Underwater Vehicles (UUVs) plays a decisive role in optimal formation control, reasonable path planning, and efficient cooperative operation. However, the traditional method has deficiency low ranging accuracy contains systematic deviation deep ocean applications, which seriously affects UUVs makes goal configuration no longer applicable. A novel acoustic ray-trace correction is proposed for localization applications. Considering bending...

Gerbera (Gerbera jamesonii Bolus ex. Hook f.) is a popular cut flower and flowering potted plant. In August 2011, new leaf spot disease was observed on double-type growing in outdoor ground beds Guangzhou, Guangdong Province, China. Approximately 30% of about 20,000 plants the Guangzhou were affected. Leaf spots round or irregular with grayish centers surrounded by dark brown borders ranged from 5 to 15 mm diameter. Leaves multiple lesions became blighted. A fungus isolated single-spore...

Doppler velocity logger (DVL) error parameters can significantly influence the navigation accuracy of DVL/strapdown inertial system (SINS) integration for unmanned underwater vehicles (UUV). To improve UUV, this study proposes a two-stage DVL calibration method aided by global satellite (GNSS) measurements. First, utilizing GNSS/SINS integrated navigation, scale factor is calculated moduli velocities in UUV body frame and instrument frame. Then, using measurements throughout process, problem...

During high dynamic gravity measurements conducted on unmanned surface vehicle, the presence of low-frequency noise caused by vertical and horizontal motion disturbances carrier in conjunction with excitation from sensor, results a direct mixture within frequency band signal. Admittedly, conventional filtering techniques such as finite impulse response (FIR) or infinite (IIR) prove insufficient eliminating measurement noise, ultimately leading to decrease accuracy.In this regard, paper...

Abstract Reasonable stochastic model and function are the premise of accurate velocity determination, especially in time-differenced carrier-phase (TDCP) method. This paper presents, first, an elevation-dependent (ESM), then gives a simplified unified Galileo/GPS combined TDCP model, where inter-system bias (ISB) variations analysed based on correlation coefficients scaled sensitivity matrix. To evaluate performance proposed models, datasets collected at 10 multi-GNSS experiment (MGEX)...