A survey: which features are required for dynamic visual simultaneous localization and mapping?

In recent years,simultaneous localization and mapping in dynamic environments(dynamic SLAM)has attracted significant attention from both academia and industry.Some pioneering work on this technique has expanded the potential of robotic applications.Compared to standard SLAM under the static world assumption,dynamic SLAM divides features into static and dynamic categories and leverages each type of feature properly.Therefore,dynamic SLAM can provide more robust localization for intelligent robots that operate in complex dynamic environments.Additionally,to meet the demands of some high-level tasks,dynamic SLAM can be integrated with multiple object tracking.This article presents a survey on dynamic SLAM from the perspective of feature choices.A discussion of the advantages and disadvantages of different visual features is provided in this article.

Design of Authoring Tool for Static and Dynamic Projection Mapping

This study introduces the design details of a tool to create interactive projection-mapping content in a convenient manner.For the proposed tool design,a homography-based camera–projector calibration method was applied with the use of red–green–blue-depth images from a Kinect V2 sensor that did not require accurate camera calibration prerequisites.In addition,the proposed tool simultaneously achieved static projection mapping that projected the image content onto a fixed object,and dynamic projection mapping that projected the image content onto a user’s body,by tracing the moving user.To verify the effectiveness of the proposed content-creation tool,users with no programming capabilities were employed to create contents that were projected onto various objects in fixed positions and a user’s body in various poses,thereby analyzing the tool’s completeness.Moreover,the projection accuracy was analyzed at different depth positions,and the projection-mapping accuracy was verified with the use of the proposed method.

A framework for multi-session RGBD SLAM in low dynamic workspace environment

Mapping in the dynamic environment is an important task for autonomous mobile robots due to the unavoidable changes in the workspace. In this paper, we propose a framework for RGBD SLAM in low dynamic environment, which can maintain a map keeping track of the latest environment. The main model describing the environment is a multi-session pose graph, which evolves over the multiple visits of the robot. The poses in the graph will be pruned when the 3D point scans corresponding to those poses are out of date. When the robot explores the new areas, its poses will be added to the graph. Thus the scans kept in the current graph will always give a map of the latest environment. The changes of the environment are detected by out-of-dated scans identification module through analyzing scans collected at different sessions. Besides, a redundant scans identification module is employed to further reduce the poses with redundant scans in order to keep the total number of poses in the graph with respect to the size of environment. In the experiments, the framework is first tuned and tested on data acquired by a Kinect from laboratory environment. Then the framework is applied to external dataset acquired by a Kinect II from a workspace of an industrial robot in another country, which is blind to the development phase, for further validation of the performance. After this two-step evaluation, the proposed framework is considered to be able to manage the map in date in dynamic or static environment with a noncumulative complexity and acceptable error level.

Forage Species Suitability Mapping for China Using Topographic, Climatic and Soils Spatial Data and Quantitative Plant Tolerances

Selecting plants adapted to the climatic and soil conditions of specific locations is essential for environmental protection and economic sustainability of agricultural and pastoral systems. This is particularly true for countries like China with a diversity of climates and soils and intended uses. Currently, proper species selection is difficult due to the absence of computer-based selection tools. Climate and soil GIS layers, matched with a matrix of plant characteristics through rules describing species tolerances would greatly improve the selection process. Better matching will reduce environmental hazards and economic risks associated with sub-optimal plant selection and performance. GIS-based climate and soil maps have been developed for China. A matrix of quantitative species tolerances has been developed for example forage species and used in combination with an internet map server that allows customized map creation. A web-based decision support system has been developed to provide current information and links to original data sources, supplementary materials, and selection strategies.

Photodissociation Dynamics of OCS at 217 nm

The S（1D2）＋CO（X1Σ＋） product channel from photodissociation of OCS at 217 nm has been measured using the DC slice velocity map imaging （VMI） technique in combination with resonance enhanced multiphoton ionization （REMPI）. Two diflerent REMPI intermediate states （1F3 and 1P1） and several pump-probe laser polarization geometries are used to detect the angular momentum polarization of the photofragmented S（1D2）. The molecular- frame polarization parameters, as well as the laboratory-frame anisotropy parameters, for individual rotational states of co-fragment CO, are determined using two diflerent full quantum theories. The measured total kinetic energy release spectrum from photodissociation of OCS indicates two dissociation channels, corresponding to the fast and slow recoiling velocities of S（1D2）, respectively. The slow channel is concluded to originate from an initial photoexcitation to the A（1A＇） state, followed by a non-adiabatic transition to the ground state. The fast channel is found to follow a coherent excitation to A（1A＇） and B（1A＇） states, where contributions of the two states are almost equal at 217 nm. The determined alignment and anisotropy parameters further indicate that the slow channel follows an incoherent excitation, while the fast channel follows a coherent excitation to A（1A＇） and B（1A＇） states with a phase di erence of π/2.

A kind of noise-induced transition to noisy chaos in stochastically perturbed dynamical system

We investigate a kind of noise-induced transition to noisy chaos in dynamical systems. Due to similar phenomenological structures of stable hyperbolic attractors excited by various physical realizations from a given stationary random process, a specific Poincar6 map is established for stochastically perturbed quasi-Hamiltonian system. Based on this kind of map, various point sets in the Poincar6＇s cross-section and dynamical transitions can be analyzed. Results from the customary Duffing oscillator show that, the point sets in the Poincare＇s global cross-section will be highly compressed in one direction, and extend slowly along the deterministic period-doubling bifurcation trail in another direction when the strength of the harmonic excitation is fixed while the strength of the stochastic excitation is slowly increased. This kind of transition is called the noise-induced point-overspreading route to noisy chaos.

A new procedure for exploring chaotic attractors in nonlinear dynamical systems under random excitations

Due to uncertain push-pull action across boundaries between different attractive domains by random excitations, attractors of a dynamical system will drift in the phase space, which readily leads to colliding and mixing with each other, so it is very difficult to identify irregular signals evolving from arbitrary initial states. Here, periodic attractors from the simple cell mapping method are further iterated by a specific Poincare map in order to observe more elaborate structures and drifts as well as possible dynamical bifurcations. The panorama of a chaotic attractor can also be displayed to a great extent by this newly developed procedure. From the positions and the variations of attractors in the phase space, the action mechanism of bounded noise excitation is studied in detail. Several numerical examples are employed to illustrate the present procedure. It is seen that the dynamical identification and the bifurcation analysis can be effectively performed by this procedure.

TENSOR SUM AND DYNAMICAL SYSTEMS

In this paper we introduce the concept of tensor sum semigroups. Also we have given the examples of tensor sum operators which induce dynamical system on weighted locally convex function spaces.

Dynamics of Open Systems with Affine Maps

Many quantum systems of interest are initially correlated with their environments and the reduced dynamics of open systems are an interesting while challenging topic. Affine maps, as an extension of completely positive maps, are a useful tool to describe the reduced dynamics of open systems with initial correlations. However, it is unciear what kind of initial state shares an affine map. In this study, we give a sumcient condition of initial states, in which the reduced dynamics can always be described by an affihe map. Our result shows that if the initial states of the combined system constitute a convex set, and if the correspondence between the initial states of the open system and those of the combined system, defined by taking the partial trace, is a bijection, then the reduced dynamics of the open system can be described by an affine map.

A Deep Learning-Based Crowd Counting Method and System Implementation on Neural Processing Unit Platform

In this paper, a deep learning-based method is proposed for crowdcountingproblems. Specifically, by utilizing the convolution kernel densitymap, the ground truth is generated dynamically to enhance the featureextractingability of the generator model. Meanwhile, the “cross stage partial”module is integrated into congested scene recognition network (CSRNet) toobtain a lightweight network model. In addition, to compensate for the accuracydrop owing to the lightweight model, we take advantage of “structuredknowledge transfer” to train the model in an end-to-end manner. It aimsto accelerate the fitting speed and enhance the learning ability of the studentmodel. The crowd-counting system solution for edge computing is alsoproposed and implemented on an embedded device equipped with a neuralprocessing unit. Simulations demonstrate the performance improvement ofthe proposed solution in terms of model size, processing speed and accuracy.The performance on the Venice dataset shows that the mean absolute error(MAE) and the root mean squared error (RMSE) of our model drop by32.63% and 39.18% compared with CSRNet. Meanwhile, the performance onthe ShanghaiTech PartB dataset reveals that the MAE and the RMSE of ourmodel are close to those of CSRNet. Therefore, we provide a novel embeddedplatform system scheme for public safety pre-warning applications.

An architecture and algorithm for green router IP lookup

Today,backbone networks deploy a large number of devices and links.This is mainly due to both redundancy purposes for network service reliability,and resource over-dimensioning for maintaining quality of service during rush hours.Unfortunately,current routers do not have power management primitives,and have constant energy consumption independent of their actual workloads.How to implement a low power and multi-stage switch forwarding for IP lookup is a challenge in high-performance green routers design.A forwarding information base multi-stage mapping routing lookup architecture is presented,and the dynamic routing table mapping algorithm is designed to determine the optimal strides for building tree bitmap tries which lead the worst-case power consumption of the IP lookup engine to be minimized.Experimental results show that the application of reallife routing tables demonstrates that the proposed method could reduce power consumption of routing lookup by 30%.

Passive walker that can walk down steps:simulations and experiments

A planar passive walking model with straight legs and round feet was discussed. This model can walk down steps, both on stairs with even steps and with random steps. Simulations showed that models with small moments of inertia can navigate large height steps. Period-doubling has been observed when the space between steps grows. This period-doubling has been validated by experiments, and the results of experiments were coincident with the simulation.

Characterization of deformation stability of in-situ TiB2/6351 composites during hot compression based on Murty criterion

In situ TiB2 reinforced 6351 Al alloy composites were subjected to compression testing at strain rates and temperatures ranging from 0.001 to 10 s -1 and from 300 to 550？欲espectively,using Gleeble-1500D system.And the associated microstructural transformations and instability phenomena were studied by observations of the optical and transmission electron microscope.The power dissipation efficiency and instability parameter were calculated following the dynamic material model and plotted with the temperature and logarithm of strain rate to obtain processing maps for strains of 0.2,0.4,and 0.6.The processing maps present the instability zones at higher strain rates.The result shows that with increasing strain,the instability zones enlarge.The microstructural examination shows that the interface separates even the particle cracks or aligns along the shear direction of the adiabatic shear band in the instability zones.Two domains of higher efficiencies correspond to dynamic recovery and dynamic recrystallization during the hot deformation.Using the processing maps,the optimum processing parameters of stain rates and temperatures can be chosen for effective hot deformation of TiB2/6351 composites.

Hot Deformation Behavior and Processing Maps of As-cast Mn18Cr18N Steel

Hot deformation behavior of as-cast Mn18Cr18 N austenitic stainless steel was studied in the temperature range of 950-1200 ℃ and strain rate range of 0.001-1 s^（-1） using isothermal hot compression tests. The true stress-strain curves of the steel were characterized by hardening and subsequent softening and varied with temperatures and strain rates. The hot deformation activation energy of the steel was calculated to be 657.4 k J/mol, which was higher than that of the corresponding wrought steel due to its as-cast coarse columnar grains and heterogeneous structure. Hot processing maps were developed at different plastic strains, which exhibited two domains with peak power dissipation efficiencies at 1150 ℃/0.001 s^（-1） and 1200 ℃/1 s^（-1）, respectively. The corresponding microstructures were analyzed by optical microscopy（OM）, scanning electron microscopy（SEM）, and electron backscatter diffraction（EBSD）. It has been confirmed that dynamic recrystallization（DRX） controlled by dislocation slipping and climbing mechanism occurs in the temperature and strain rate range of 1050-1200 ℃ and 0.001-0.01 s^（-1）; And DRX controlled by twinning mechanism occurs in the temperature and strain rate range of 1100-1200 ℃, 0.1-1 s^（-1）. These two DRX domains can serve as the hot working windows of the as-cast steel at lower strain rates and at higher strain rates, respectively. The processing maps at different strains also exhibit that the instability region decreases with increasing strain. The corresponding microstructures and the less tensile ductility in the instability region imply that the flow instability is attributed to flow localization accelerated by a few layers of very fine recrystallized grains along the original grain boundaries.

Hot deformation characteristics of as-cast high-Cr ultra-super-critical rotor steel with columnar grains

Isothermal hot compression tests of as-cast high-Cr ultra-super-critical（USC） rotor steel with columnar grains perpendicular to the compression direction were carried out in the temperature range from 950 to 1250°C at strain rates ranging from 0.001 to 1 s^（-1）. The softening mechanism was dynamic recovery（DRV） at 950°C and the strain rate of 1 s^（-1）, whereas it was dynamic recrystallization（DRX） under the other conditions. A modified constitutive equation based on the Arrhenius model with strain compensation reasonably predicted the flow stress under various deformation conditions, and the activation energy was calculated to be 643.92 kJ ×mol^（-1）. The critical stresses of dynamic recrystallization under different conditions were determined from the work-hardening rate（θ）–flow stress（σ） and-θ/σ–σ curves. The optimum processing parameters via analysis of the processing map and the softening mechanism were determined to be a deformation temperature range from 1100 to 1200°C and a strain-rate range from 0.001 to 0.08 s^（-1）, with a power dissipation efficiency η greater than 31%.

Highway Toll Collection Method for Connected Automated Vehicle Platooning Using Spatio-Temporal Grid Reservation

In the intelligent transportation system, the autonomous vehicle platoon is a promising concept for addressing traffic congestion problems. However, under certain conditions, the platoon’s advantage cannot be properly developed, especially when stopping for electronic toll collection (ETC) to pay the toll fee using the highway. This study proposes a software architectural platform that enables connected automated vehicles to reserve a grid-based alternative approach to replace current highway toll collection systems. A planned travel route is reserved in advance by a connected automated vehicle in a platoon, and travel is based on reservation information. We use driving information acquired by communication mechanisms installed in connected automated vehicles to develop a dynamic map platform that collects highway toll tax based on reserving spatio-temporal grids. Spatio-temporal sections are developed by dividing space and time into equal grids and assigning a certain road tax rate. The results of the performance evaluation reveal that the proposed method appropriately reserves the specified grids and collects toll taxes accurately based on a spatio-temporal grid with minimal communication time and no data package loss. Likely, using the proposed method to mediate driving on a one-kilometer route takes an average of 36.5 seconds, as compared to ETC and the combination of ETC and freeway road lane methods, which take 46.6 and 53.8 seconds, respectively, for 1000 vehicles. Consequently, our proposed method’s travel time improvements will reduce congestion by more effectively exploiting road capacity as well as enhance the number of platoons while providing non-stoppable travel for autonomous vehicles.

Intratree Variation in Viscoelastic Properties of Cell Walls of Masson Pine (Pinus Massoniana Lamb)

In this study,Pinus massoniana Lamb at different heights,across the annual rings,and between earlywood and latewood was measured by X-ray diffraction and the chemical composition was analyzed by chemical treatment.Results indicated that the microfibril angle(MFA)decreased and the chemical composition changed little with the increase in height from 1 m to 9 m.In the radial direction,the MFA decreased and the chemical composition changed little with an increase in annual rings.The cellulose content of latewood was higher than that of early-wood.The viscoelastic changes of wood cell walls at different heights,across the annual rings by the method of quasi-static nanoindentation and dynamic modulus mapping techniques.Results indicated that the wood cell walls’elastic modulus increased,and the creep rate and creep compliance decreased with the increase in height;The elastic modulus and hardness increased with the annual rings.The cell walls’storage modulus increased and the loss modulus gradually decreased with an increase in height;the storage modulus gradually increased and the loss modulus decreased with the annual rings.

Dynamic load balancing algorithm for distributed system

In distributed systems, it is important to adjust load distribution dynamically based on server performance and load information. Meanwhile, gray release and rapid expansion are the basic requirements to ensure reliability and stability for systems with short version iteration cycles. The traditional Hash algorithm performs poorly in gray release, rapid expansion, and load distribution. To solve these problems, a novel Hash-based dynamic mapping(HDM) load balancing algorithm was proposed. On the one hand, this algorithm can adjust the load distribution dynamically based on server performance and load information. On the other hand, it implements gray release by controlling the ratio of requests assigned to the changed nodes. Additionally, HDM has a higher expansion efficiency. Experiments show that the HDM distributes the load more reasonably, provides a more stable gray release ratio, and has a higher expansion efficiency.

Secular dynamics of navigation satellites in the MEO and GSO regions

In this study,a dynamical model is developed to describe the secular evolution of navigation satellites under the geocentric reference frame with the Laplace orbit as the fundamental plane.The disturbing function,involving the effects of Earth's oblateness and lunisolar gravitational attraction,is averaged over the orbital periods of both the satellite and the perturbers.In the regions of medium-Earth orbits and geosynchronous orbits,there are varieties of lunisolar resonances for governing the secular dynamics of navigation satellites.Among these resonances,we are interested in the ones occurring at the critical inclinations as well as the lunar node resonances.For each resonance of interest,the resonant center and width are identified analytically.Finally,dynamical maps are compared with the analytical results.

An open source, server-side framework for analytical web mapping and its application to health

In this paper,we detail the design and the implementation of an open source,server-side web mapping framework for the analysis of health data.The frame-work forms part of a larger project,the goal of which is to provide an analytical web geographical information system(GIS)that enables health experts to analyse spatial aspects of health data.The aim of the framework is to provide a method for the dynamic and flexible spatial visualisation of health data to facilitate data exploration and analysis.Consequently,a dynamic thematic web mapping technique,an extension to the Open Geospatial Consortium(OGC)web map service standard,was developed.The technique combines a data query,processing technique and styling methodology on the fly to generate a thematic map.The resulting thematic map represents a virtual map layer that enables a user to rapidly visually summarise properties of a data-set.A test web interface was developed to assess the efficacy of the web mapping technique.As the dynamic web mapping method builds on existing OGC web mapping standards,it can be readily integrated with the existing lightweight slippy map web clients and virtual globes.