Reference satellite selection method for GNSS high-precision relative positioning

Selecting the optimal reference satellite is an important component of high-precision relat/ve positioning because the reference satellite directly influences the strength of the normal equation. The reference satellite selection methods based on elevation and positional dilution of precision （PDOP） value were compared. Results show that all the above methods cannot select the optimal reference satellite. We introduce condition number of the design matrix in the reference satellite selection method to improve structure of the normal equation, because condition number can indicate the ill condition of the normal equation. The experimental results show that the new method can improve positioning accuracy and reliability in precise relative positioning.

A cluster positioning architecture and relative positioning algorithm based on pigeon fock bionics

Unmanned clusters can realize collaborative work,fexible confguration,and efcient operation,which has become an important development trend of unmanned platforms.Cluster positioning is important for ensuring the normal operation of unmanned clusters.The existing solutions have some problems such as requiring external system assistance,high system complexity,poor architecture scalability,and accumulation of positioning errors over time.Without the aid of the information outside the cluster,we plan to construct the relative position relationship with north alignment to adopt formation control and achieve robust cluster relative positioning.Based on the idea of bionics,this paper proposes a cluster robust hierarchical positioning architecture by analyzing the autonomous behavior of pigeon focks.We divide the clusters into follower clusters,core clusters,and leader nodes,which can realize fexible networking and cluster expansion.Aiming at the core cluster that is the most critical to relative positioning in the architecture,we propose a cluster relative positioning algorithm based on spatiotemporal correlation information.With the design idea of low cost and large-scale application,the algorithm uses intra-cluster ranging and the inertial navigation motion vector to construct the positioning equation and solves it through the Multidimensional Scaling(MDS)and Multiple Objective Particle Swarm Optimization(MOPSO)algorithms.The cluster formation is abstracted as a mixed direction-distance graph and the graph rigidity theory is used to analyze localizability conditions of the algorithm.We designed the cluster positioning simulation software and conducted localizability tests and positioning accuracy tests in diferent scenarios.Compared with the relative positioning algorithm based on Extended Kalman Filter(EKF),the algorithm proposed in this paper has more relaxed positioning conditions and can adapt to a variety of scenarios.It also has higher relative positioning accuracy,and the error does not accumulate over time.

Impact of sampling interval on variance components of epoch-wise residual error in relative GPS positioning: A case study of a 40-km-long baseline

The study presents sampling interval impacts on variance components of the epoch-wise residual errors in relative GPS positioning. In the variance components estimation process, the 2-way nested ANOVA method was used. For that purpose, GPS observation data during four months at two permanent GPS stations, establishing a 40-km-long baseline as a part of the Montenegrin permanent network(Monte Pos), were used. The study results showed that there is no statistically significant impact of sampling interval changes on epoch-wise variance components related to the residual tropospheric and ionospheric delays(effect a) when it comes to such a baseline. However, it is not the case with epoch-wise variance components related to the interstation-distance-independent residual ‘far-field’ multipath effect(effect b). It turned out that the absolute values of relative differences of standard deviations of the effect a on the relative GPS coordinates(e, n and u) had maximum values 11.1%, 10.2% and 8.9%,respectively. Keeping the same order of presentation for the effect b, the values of 5.9%, 9.9% and 12.5%were obtained. In addition, absolute values of relative differences of standard deviations of horizontal and vertical position had maximum values of 3.8% and 7.7%, respectively.

Dependence of epoch-wise two-way nested ANOVA estimates of variances of unmodeled effects present in relative GPS positioning on satellite elevation cutoff angle and PDOP mask

Impact of satellite elevation cutoff angle and position dilution of precision(PDOP)mask change on epoch-wise variance components of unmodeled effects that accompany relative Global Positioning System(GPS)positioning is presented herein.Data used for this study refer to the winter and summer periods of the years with minimal(2008)and maximal(2013)solar activity.These data were collected every 30 s in static mode,at two permanent GPS stations located in Montenegro,establishing a mediumdistance(116-km-long)baseline with a height difference of approximately 760 m between its endpoints.The study showed that changing satellite elevation cutoff angle,with a fixed PDOP mask,affects epochwise two-way nested ANOVA estimates of variances related to the‘far-field’multipath(considered as the nested factor herein)and the combined unmodeled effect of tropospheric and ionospheric refraction(considered as the nesting factor herein).However,changing of PDOP mask,with a fixed satellite elevation cutoff angle,doesn’t affect epoch-wise two-way nested ANOVA estimate of variance of the combined unmodeled effect of tropospheric and ionospheric refraction,but,generally,affects the estimate of variance of the‘far-field’multipath(possibly mixed with a part of a‘shorter-term’ionospheric refraction),which is especially pronounced for the summer period.It should also be noted that there is a significant influence of satellite elevation cutoff angle change on both epoch-wise horizontal and vertical position accuracy,only for the summer period,especially in the presence of maximal solar activity,while there is no significant impact of PDOP mask change on epoch-wise positional accuracy.

Relative-Position Estimation Based on Loosely Coupled UWB–IMU Fusion for Wearable IoT Devices

Relative positioning is one of the important techniques in collaborativerobotics, autonomous vehicles, and virtual/augmented reality (VR/AR)applications. Recently, ultra-wideband (UWB) has been utilized to calculaterelative position as it does not require a line of sight compared to a camerato calculate the range between two objects with centimeter-level accuracy.However, the single UWB range measurement cannot provide the relativeposition and attitude of any device in three dimensions (3D) because oflacking bearing information. In this paper, we have proposed a UWB-IMUfusion-based relative position system to provide accurate relative positionand attitude between wearable Internet of Things (IoT) devices in 3D. Weintroduce a distributed Euler angle antenna orientationwhich can be equippedwith the mobile structure to enable relative positioning. Moving average andmin-max removing preprocessing filters are introduced to reduce the standarddeviation. The standard multilateration method is modified to calculate therelative position between mobile structures. We combine UWB and IMUmeasurements in a probabilistic framework that enables users to calculatethe relative position between two nodes with less error. We have carried outdifferent experiments to illustrate the advantages of fusing IMU and UWBranges for relative positioning systems. We have achieved a mean accuracy of0.31m for 3D relative positioning in indoor line of sight conditions.

Influence of relative positions between RF coil and crucible on sapphire crystals by edge-defined film-fed growth(EFG) technique

To obtain the stable temperature field required for growing sapphire crystals, the influence of relative positions between RF coil and crucible on the performances of sapphires produced by edge-defined film-fed growth（EFG） technique was investigated. For comparison, the crucible was located at the top（case A） and the middle（case B） of the RF coil, respectively. Furthermore, the lattice integrities were studied by the double-crystal X-ray diffraction, and the dislocations were observed under the optical microscope and atomic force microscope after corroding in molten KOH at 390 ℃. The crystals in case B exhibit better lattice integrity with smaller full width at half maximum of 29.13 rad·s, while the value in case A is 45.17 rad·s. The morphologies of dislocation etch pits in both cases show typical triangular symmetry with smooth surfaces. However, the dislocation density of 2.8×104 cm-2 in case B is only half of that in case A, and the distribution is more uniform, compared to the U-shaper in case A.

Influence of Inner/Outer Stator Pole Ratio and Relative Position on Electromagnetic Performance of Partitioned Stator Switched Flux Permanent Magnet Machines

Based on the 6-pole outer stator(armature winding-stator),the influence of inner(permanent magnet-stator)/outer stator pole ratio n(n=NIS/NOS),stator relative positions and rotor pole number combinations on electromagnetic performance of partitioned stator switched flux permanent magnet(PM)machines(PS-SFPMMs)is investigated in this paper.Since the armature windings and PMs are located in two separated stators and PMs are stationary,PS-SFPMMs have high fault tolerance capabilities.To maximize the torque performance,the PM of inner stator pole should be aligned with outer stator pole when n is odd while the iron rib of inner stator pole should be aligned with outer stator pole when n is even.No matter what n is selected,the rotor pole number NR can be any integers except the phase number and its multiples.The analysis results indicate that the optimal NR is closed to(NIS+NOS)/2 and it is odd when n is odd while it is even when n is even.Meanwhile,symmetrical phase back-EMF waveform will be obtained when the ratio of Min(NOS,NIS)to the greatest common divisor of Min(NOS,NIS)and NR is even.Based on the optimal rotor pole numbers for 6-pole outer stator with different n and corresponding optimal relative position together with same rated copper loss,the average torque is improved by 18.4%,25.1%and 25.7%respectively in PS-SFPMMs with n equal to 2,3 and 4 when compared with PS-SFPMM with n equal to 1.The analyses are validated by experiment results of the prototype machine.

Research on Indoor Passive Positioning Technology Based on WiFi

In recent years,WiFi indoor positioning technology has become a hot research topic at home and abroad.However,at present,indoor positioning technology still has many problems in terms of practicability and stability,which seriously affects the accuracy of indoor positioning and increases the complexity of the calculation process.Aiming at the instability of RSS and the more complicated data processing,this paper proposes a low-frequency filtering method based on fast data convergence.Low-frequency filtering uses MATLAB for data fitting to filter out low-frequency data;data convergence combines the mean and multi-data parallel analysis process to achieve a good balance between data volume and system performance.At the same time,this paper combines the position fingerprint and the relative position method in the algorithm,which reduces the error on the algorithm system.The test results show that the strategy can meet the requirements of indoor passive positioning and avoid a large amount of data collection and processing,and the average positioning error is below 0.5 meters.

Relative Position and Attitude Control for Drag-Free Satellite with Prescribed Performance and Actuator Saturation

An adaptive prescribed performance control scheme is proposed for the drag free satellite in the presence of actuator saturation and external disturbances.The relative translation and rotation dynamics between the test mass and outer satellite are firstly derived.To guarantee prescribed performance bounds on the transient and steady control errors of relative states,a performance constrained control law is formulated with an error transformed function.In addition,the requirements to know the system parameters and the upper bound of the external disturbance in advance have been eliminated by adaptive updating technique.A command filter is concurrently used to overcome the problem of explosion of complexity inherent in the backstepping control design.Subsequently,a novel auxiliary system is constructed to compensate the adverse effects of the actuator saturation constrains.It is proved that all signals in the closed?loop system are ultimately bounded and prescribed performance of relative position and attitude control errors are guaranteed.Finally,numerical simulation results are given to demonstrate the effectiveness of the proposed approach.

Design of relative position sensing system for high-speed maglev train

In the high-speed maglev system,accurate real-time information of the train position is essential forstable,safe and efficient train operation.To detect the relative position of the high-speed maglev trainfrom a reference position,a location method based on long stator slot detection was proposed.Besides,aprototype system has been successfully developed.The hardware structure of the system,as well as itsworking principle was described.Moreover,a subdivision algorithm for calculating the pole location anglesignal was elucidated.Experiments show that the proposed method is feasible.The technical indexes ofthe detection system satisfy the requirements of the vehicle operation control system.The relative positionsensing system can be put into practice.

Gly-LysPred: Identification of Lysine Glycation Sites in Protein Using Position Relative Features and Statistical Moments via Chou’s 5 Step Rule

Glycation is a non-enzymatic post-translational modification which assigns sugar molecule and residues to a peptide.It is a clinically important attribute to numerous age-related,metabolic,and chronic diseases such as diabetes,Alzheimer’s,renal failure,etc.Identification of a non-enzymatic reaction are quite challenging in research.Manual identification in labs is a very costly and timeconsuming process.In this research,we developed an accurate,valid,and a robust model named as Gly-LysPred to differentiate the glycated sites from non-glycated sites.Comprehensive techniques using position relative features are used for feature extraction.An algorithm named as a random forest with some preprocessing techniques and feature engineering techniques was developed to train a computational model.Various types of testing techniques such as self-consistency testing,jackknife testing,and cross-validation testing are used to evaluate the model.The overall model’s accuracy was accomplished through self-consistency,jackknife,and cross-validation testing 100%,99.92%,and 99.88%with MCC 1.00,0.99,and 0.997 respectively.In this regard,a user-friendly webserver is also urbanized to accumulate the whole procedure.These features vectorization methods suggest that they can play a critical role in other web servers which are developed to classify lysine glycation.

An adaptive routing protocol based on relative positions in VANETs

After presenting weaknesses of several classic routing protocols applied in vehicular ad hoc networks （VANETs） by a qualitative comparison, this paper proposes a novel self-adaptive routing protocol, named ARPP. With respect to the specific characteristics of VANETs, the proposed routing protocol adopts a dynamic topology establishment and time-varying control message sending mechanism. A direction-based forwarding strategy and a specific warning solution enhance the routing performance in ARPP. Simulation results show that the ARPP protocol outperforms the classic AODV in urban vehicle environment.

A stealthy method to determine the relative position and velocity for satellite formation flying

To achieve the satellite formation control and the succeed formation missions, we present a new stealthy method to determine the relative states between formation satellites. In this method, the combination of a CCD camera and laser radar is used as the relative measure sensors. To reduce electromagnetic radiation, the laser radar works intermittently to minimize the probability of being discovered. And an unscented Kalman filter (UKF) is applied to estimate the relative states. The observability of this method is analyzed. The validity and effectiveness of the method is demonstrated in a typical application of formation relative navigation.

The Influence of Surface Building's Relative Position on the Seismic Response of Subway Structures

By using the finite element method and viscoelastic artificial boundary, a soil-structure interaction system is established to simulate the influence of surface buildings on the seismic response of subway structures. The conditions of different relative positions between ground building and subway structure are analyzed. The result~ indicate that when considering the existence of surface buildings, the relative story displacements and internal forces of subway structures are changed greatly. Further the influence of surface buildings on subway structure changes as the distance increases.

NOTES ON THE LOG-BRUNN-MINKOWSKI INEQUALITY

Böröczky-Lutwak-Yang-Zhang proved the log-Brunn-Minkowski inequality for two origin-symmetric convex bodies in the plane in a way that is stronger than for the classical Brunn-Minkowski inequality.In this paper,we investigate the relative positive center set of planar convex bodies.As an application of the relative positive center,we prove the log-Minkowski inequality and the log-Brunn-Minkowski inequality.

PCATNet: Position-Class Awareness Transformer for Image Captioning

Existing image captioning models usually build the relation between visual information and words to generate captions,which lack spatial infor-mation and object classes.To address the issue,we propose a novel Position-Class Awareness Transformer(PCAT)network which can serve as a bridge between the visual features and captions by embedding spatial information and awareness of object classes.In our proposal,we construct our PCAT network by proposing a novel Grid Mapping Position Encoding(GMPE)method and refining the encoder-decoder framework.First,GMPE includes mapping the regions of objects to grids,calculating the relative distance among objects and quantization.Meanwhile,we also improve the Self-attention to adapt the GMPE.Then,we propose a Classes Semantic Quantization strategy to extract semantic information from the object classes,which is employed to facilitate embedding features and refining the encoder-decoder framework.To capture the interaction between multi-modal features,we propose Object Classes Awareness(OCA)to refine the encoder and decoder,namely OCAE and OCAD,respectively.Finally,we apply GMPE,OCAE and OCAD to form various combinations and to complete the entire PCAT.We utilize the MSCOCO dataset to evaluate the performance of our method.The results demonstrate that PCAT outperforms the other competitive methods.

Relative position of seeds driven the seedling growth are mediated by root-leaf traits

Variations in plant traits are indicative of plant adaptations to forest environments,and studying their relationships with tree growth provides valuable insights into forest regeneration.The spatial arrangement of plant seeds within the forest litter or soil critically infuences the variations of root-leaf traits,thereby affecting the adaptive strategies of emerging seedlings.However,our current understanding of the impacts of individual root-leaf traits on seedling growth in different relative position,and whether these traits together affect growth,remains limited.This study focuses on the dominant tree species,Castanopsis kawakamii,within the Sanming C.kawakamii Nature Reserve of China.The present experiment aimed to examine the variations in root-leaf traits of seedling,focus on the relative positions of seeds within different layers:beneath or above the litter layer,or within the bare soil layer(without litter).Our fndings provided evidence supporting a coordinated relationship between root and leaf traits,wherein leaf traits varied in conjunction with root traits in the relative positions of seeds.Specifcally,we observed that seedlings exhibited higher values for specifc leaf area and average root diameter,while displaying lower root tissue density.The mixed model explained 86.1%of the variation in root-leaf traits,surpassing the variation explained by the relative positions.Furthermore,soil nitrogen acted as a mediator,regulating the relationship between seedling growth and root-leaf traits,specifcally leaf dry matter content and root tissue density.Therefore,future studies should consider artifcially manipulating tree species diversity based on root-leaf traits characteristics to promote forest recovery.

Assessing the socio-cultural impact of urban revitalisation using Relative Positive Impact Index(RPII)

Urban heritage is a vital resource that connects communities to their local identity.Unplanned developments and rapid urbanisation often harm the authenticity of historic areas,disrupting the cultural fabric and altering their character.This study introduces the Relative Positive Impact Index(RPll),a novel technique for assessing the socio-cultural impacts of urban revitalisation.The significance of RPII lies in its ability to quantitatively evaluate the impacts on the cultural fabric and integrity of historic urban areas,which is crucial for sustainable urban development.The study's objective is to apply RPII in evaluating qualitative socio-cultural characteristics in historic urban areas,with a focus on four main criteria and 16 sub-criteria,in the case of the Kuttichira precinct.The methodology integrates the analysis of published literature,a quantitative survey mapping the stakeholders'perception,and qualitative insights.This approach facilitates an in-depth understanding of how urban revitalisation affects local socio-cultural dynamics,preserving the authenticity and character of historic areas.The study reveals that the revitalisation project in Kuttichira positively impacts the socio-cultural fabric of the area,maintaining cultural integrity and addressing social challenges.These findings offer valuable insights for sustainable urban development and policymaking in historic areas.The study recommends the application of RPll in other urban precincts for comparative analysis and further development of urban development practices,contributing to informed urban policy and planning decisions.

PRINCIPLE,SOFTWARE AND EXPERIMENT OF GPS-SUPPORTED AEROTRIANGULATION

In conventional aerial photogrammetry, the high accurate photogrammetric point determination is always carried out by aerotriangulation using a great deal of ground control points around the perimeter and in the center of block area because the exterior orien- tation parameters of aerial photographs are unknown. A technological revolution in pho- togrammetry has taken place since Navstar global positioning system (GPS) was applied to determine the 3D coordinates of exposure station positions during the photo flight missions. GPS-supported aerotriangulation is conducted by a combined bundle adjustment for pho- togrammetric observations and the camera orientation data. In this case, the essential ground control points are replaced by GPS-determined camera positions. Recent investigations show this method is coming to the practice. We have been engaged in the theoretical studies, soft- ware development, and related experiments and production in the field since 1990. So far the abundant research achievements are obtained in terms of the theory and application. In this paper,we first derives the mathematical model of GPS-supported aerotriangulation from the geometry between camera and airborne GPS antenna, then describes briefly a software pack- age WuCAPS (Wuhan combined adjustment program system) developed newly by the au- thor,which serves the purpose of the combined bundle adjustment for photogrammetric and non-photogrammetric observations. At the end of the present work, a set of actual aerial pho- tographs,at the image scale of 1: 34 000, with airborne GPS data taken from Tianjing site, China were processed by WuCAPS. The empirical results have verified that the accuracy of the combined bundle adjustment with 4 XYZ ground control points around the corners of block area is very close to that of the conventional bundle adjustment with 3 additional pa- rameters, that leads to reduce 88% field survey and 75% production cost, and can meet the specification of topographic mapping at small or medium scale by GPS-supported aerotriangu- lation without ground control. This shows the ample applicability and the economic benefit of kinematic GPS relative positioning in high accurate photogrammetric point determination.

DUAL QUATERNION CURVE INTERPOLATION ALGORITHM FOR FORMATION SATELLITES

The traditional algorithms for formation flying satellites treat the satellite position and attitude sepa- rately. A novel algorithm combining satellite attitude with position is proposed. The principal satellite trajectory is obtained by dual quaternion interpolation, then the relative position and attitude of the deputy satellite are ob- tained by dual quaternion modeling on the principal satellite. Through above process, relative position and atti- tude are unified. Compared with the orbital parameter and the quaternion methods, the simulation result proves that the algorithm can unify position and attitude, and satisfy the precision requirement of formation flying satel- lites.