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High-order inverse dynamics is important for the trajectory tracking control of the elastic-joint manipulators. Usually it is undesirable to establish third-order or fourth-order inverse dynamics through the symbolic Lagrangian method, because of its complicated customization and higher computational complexity, which is not suitable for real-time control for multi-joint [Formula: see text] manipulators. Based on the Subsystem of Newton-Euler formulation and the recently proposed elastic joint Newton-Euler algorithm (EJNEA), a novel recursive algorithm (Sub-EJNEA) is proposed in this paper. The Sub-EJNEA obtains a linear complexity [Formula: see text], and has a more compact form and clear physical meaning. Based on the Sub-EJNEA, a recursive control method is proposed, which can be seen as an enhancement of the feedback linearization (FL-E) control method. When facing with friction and external disturbances, a combined controller FL-E-RISE is proposed. Finally, to verify the correctness of the recursive algorithm and the effectiveness of the proposed control schemes, simulation results with the Baxter manipulator are presented.

This paper proposed a novel finite-time disturbance observer-based recursive fractional-order sliding mode control (FTRFOSMC) algorithm under disturbances and input saturation for redundantly actuated cable driving parallel robots (RCDPRs). A recursive fractional-order sliding mode surface composed of the fractional-order non-singular fast terminal sliding mode function and an integral term is constructed, and the fast response convergence and high precision tracking performance can be obtained for the recursive characteristics of the proposed sliding mode surface; meanwhile, an auxiliary system is designed to overcome the adverse effects of the input saturation. Then, to compensate the model uncertainty and external disturbances, an adaptive finite-time disturbance observer is developed, and the estimation error can be stabilized in finite-time for unknown bound of the disturbance and its derivative. The stability of the proposed controller was investigated by the Lyapunov stability theory. Finally, numerical simulations with the software of the MATLAB/Simuink are conducted to verify the effectiveness of the proposed controller.

Tendinopathy is a common musculoskeletal disorder which results in chronic pain and reduced performance. The therapeutic effect of stem cell derived-small extracellular vesicles (sEVs) for tendinopathy has been validated in recent years. However, whether large extracellular vesicles (lEVs), another subset of extracellular vesicles, possesses the ability for the improvement of tendinopathy remains unknown. Here, we showed that lEVs secreted from iPSC-derived MSCs (iMSC-lEVs) significantly mitigated pain derived from tendinopathy in rats. Immunohistochemical analysis showed that iMSC-lEVs regulated the heterogeneity of infiltrated macrophages and several inflammatory cytokines in rat tendon tissue. Meanwhile

Human activity in the polar regions is increasing, and as a result of this, the positioning performance of global navigation satellite systems (GNSSs) in these regions is attracting more attention. Since the constellation design of GNSS systems (such as GPS, GLONASS, Galileo, and BDS) only provides superior coverage for human activity in the middle and low latitudes, the elevation angles of GNSS satellites are lower in the polar regions. In this study, the authors first analyzed the availability of GPS, GLONASS, Galileo, and BDS in the polar regions using the classic geometric dilution of precision (GDOP) metric. It was discovered that if only a stand-alone navigation system is employed, satellite visibility in the Arctic and Antarctic regions is excellent, but the GDOP is much higher than in the middle and low latitudes areas. Another interesting phenomenon is that a single navigation system other than GPS (i.e., GLONASS, Galileo, or BDS) will have some areas that cannot be located in the middle and low latitudes and will not appear in the polar regions. A simple solution of this problem is to combine multiple navigation systems to attain better GDOP. In reality, there are currently few achievable or practical solutions for the weight ratio of different satellites in the actual multi-system combined GDOP algorithm. Based on the signal-in-space analysis of different GNSS satellites, the authors propose a NEW WDOP metric for the spatial constellation configuration of multi-GNSSs, including detailed mathematical models and algorithms. The NEW WDOP metric was then used to assess the availability of multi-GNSSs in the polar regions with dual-system, three-system, and four-system combinations. This study thus draws some conclusions using the NEW WDOP model and measured data. In particular, when navigating and positioning in polar regions with a stand-alone GNSS, the mean of the NEW WDOP values is approximately 2.5, and there are many outlier values. Meanwhile, the mean of the NEW WDOP values with the dual GNSS combinations is

Purpose The present study aimed to evaluate the genetic diagnostic yield and accuracy of exome sequencing in Chinese patients with split hand–foot malformation (SHFM), a severe heterogeneous congenital anomaly characterized by hypodevelopment of the central ray of the hands and feet. Methods A cohort of seven families and five sporadic patients with SHFM was investigated. Genomic DNA was prepared from the peripheral blood of affected as well as unaffected individuals. Whole exome sequencing (WES) was performed to identify the pathogenic mutations. Array-based comparative genomic hybridization (aCGH), CytoScan, quantitative polymerase chain reaction (qPCR), and Sanger sequencing were performed to validate the findings of WES. WES data of an additional cohort of 24 patients with non-SHFM congenital hand anomalies were analyzed as the control. Results Pathogenic variants of TP63, c.G956A p.R319H, and c.T602A:p.L201H, were identified in two families by WES. In the remaining patients, copy number analysis of the WES data by XHMM software identified pathogenic 10q 24 duplication in five individuals from three families, which was further validated via CytoScan and qPCR; however, WES could not detect duplication in 10q24 in an additional cohort of 24 individuals with non-SHFM congenital hand anomaly. Importantly, qPCR analysis of the 10q24 region copy number revealed a definite consistency with WES data in all individuals. Genotype–phenotype analysis did not present any unique feature that could differentiate between the families with TP63 mutation and 10q24 duplication. Conclusions Our study demonstrated that WES is an accurate and sensitive method to detect the pathogenic 10q24 duplication. Collectively, with TP63 mutation, a single WES testing could yield a diagnosis rate of about 40% (5/12) for the SHFM patients, at least in our cohort. As the genotype–phenotype correlation remains unclear, WES could be used as a cost-effective method for the genetic diagnosis of SHFM.

A recursive dynamic modeling and control is presented for the dual-arm manipulator with elastic joints carrying a common object. For decoupling the effect of elastic joints, the dynamic modeling approach is based on the classic recursive Newton-Euler method but involves high-order derivatives of motion and force variables. The high-order inverse kinematics which is needed in the motion control is presented firstly. With the classic Recursive Newton-Euler (RNEA) method, two-order dynamic model of the dual-arm robot is established, for decoupling the effect of the elastic joints, the form of four-order dynamic model is presented, meanwhile, combining with the high-order dynamic model of the carried object, the completed Dual-Arm Elastic Joints Newton-Euler Algorithm (DA-EJNEA) is established. Then the feedback linearization method is adopted to the motion control based on the DA-EJNEA. Finally, to verify the effectiveness of the proposed method, feedback linearization method based on the DA-EJNEA and the computed torque method based on the dynamic model with rigid joints are used to control the dual-arm coordinated system respectively, the simulation results illustrate the feedback linearization method based on the DA-EJNEA has an obvious advantage for trajectory tracking of the object in the operation space, it behaves reasonable potentials for the model-based control.

The Hatch filter has been widely used in GNSS kinematic positioning and navigation. However, the classic carrier smoothing of code pseudorange observations often results in filter divergence and accuracy degradation in the positioning solution due to the influence of ionospheric delay. One solution is to reduce the impact of ionospheric delay by using the Klobuchar model, which has low correction accuracy. Another solution is to use differential ionospheric delay correction data provided by third parties, which have a high correction accuracy. However, this solution requires the support of obtaining precise ionospheric data through a customized data network. In this study, the authors model the ionospheric delay from the observations themselves and build a mathematical model of the ionospheric delay and its variations. A new and improved Hatch filtering algorithm is proposed. The carrier smoothing of code pseudorange observations in this algorithm has high accuracy and stability because it eliminates the influence of ionospheric delay and variation simultaneously. A sliding average window with an overlap segment is designed for this algorithm, which eliminates the discontinuity in the smoothed data. The analyses in this paper have been performed by means of a set of experimental tests using Trimble, some NETR9 receivers, and a GNSS data processing platform called GNSSer. The executed field tests cover two low kinematic experiments: a ship experiment and a trolley experiment. The results show that the improved Hatch filtering algorithm eliminates most of the influence of the ionosphere and obtains carrier-smoothing pseudorange observations with smoothness and high accuracy. In the kinematic experiment of the ship position, single-frequency pseudorange observations are used to establish an observation equation. The horizontal accuracy of the ship position is approximately 50 cm, and the vertical accuracy is less than 1 m, which is an order of magnitude higher than the accuracy of the classic Hatch filter. However, the kinematic positioning of the trolley is better, the accuracy is within 10 cm in the horizontal and 10–15 cm in the vertical. Both tests show consistent results that the improved Hatch filter has excellent single-frequency, single-epoch positioning performance under low kinematic conditions.

Bacteria induced infection remains a serious medical hazard to humans. Antibacterial polymeric materials, which can kill or inhibit bacteria by disrupting cell membranes, inhibiting certain enzymes, or interfering with the transcription or synthesis of DNA or RNA, have been applied to reduce or inhibit microbial drug resistance. Herein, amino acid-based ionic liquids (ILs) and poly(ionic liquid) (PIL) membranes were synthesized and used as antibacterial materials to treat skin wounds infected by methicillin-resistant

This paper presents an systematic dynamic modeling and performance analysis method of an over-constrained 2PUR-PSR parallel manipulator with parasitic motions, where P, U, S, and R represent the prismatic joint, universal joint, spherical joint, and revolute joint, respectively. The process of the deduction of the over-constrained forces/moment is given. The Newton–Euler approach and natural orthogonal complement method are adopted to establish two types of dynamic models with and without constrained forces/moments with the consideration of the over-constrained forces/moments. The dynamic manipulability ellipsoid, which measures the uniformity of changing the position and orientation of the manipulator’s moving platform, is adopted to evaluate the dynamic performance of the parallel manipulator. To show the feasibility of the proposed method, numerical simulations are conducted to investigate the dynamic models and performance of the 2PUR-PSR manipulator. The actuation forces, constrained forces/moments, and the compatible deformation are calculated. Distribution of the DME index is also obtained. The proposed modeling approach provides a fundamental basis for the structural optimization and control scheme design of the over-constrained parallel manipulator.

To cope with the construction and upgrading of GNSS, critical attention must be given to the maintainability, reusability, extensibility, portability, loose coupling capacity and flexibility of GNS...

The Global Navigation Satellite System (GNSS) has been an indispensable tool for geodetic surveying and geodynamics research and has rapidly developed over the past few years with abundant ground networks, modern constellations and multiple signal frequencies. However, due to increasing numbers of stations and satellites, the data processing burden has increased significantly. In this contribution, an improved parallel computing method is proposed for processing large GNSS network datasets. First, a parallelization strategy is introduced for the traditional GNSS processing model by analyzing the practicability of parallel integrated processing for GNSS network data. In addition, to maximize the advantages of modern microprocessors and local area network environments, we present the multi-core parallel computing of traditional GNSS data processing methods; then, the product is released as a service-oriented architecture that can be found and invoked through multiple nodes in the Internet. Obviously, this method combines the advantages of multi-core parallelism and network parallelism. Experiments show that the efficiency of the proposed method can be further increased with the accumulation of GNSS data and additional nodes. For example, in a network with 2000 stations, the efficiency of the parallel scheme with four quad-core nodes is at least 8 times faster than that of the traditional serial scheme. All the results demonstrate that the proposed strategy is an efficient and promising approach for processing large GNSS network datasets.

GNSS Data Preprocessor is a multi-GNSS data preprocessing software designed to process raw GNSS observation data in the Receiver Independent Exchange Format 2.x to 3.x standard. Published under a free and open-source license, LGPL (GNU Lesser General Public License), written in object-oriented programming language C#, it mainly includes multi-GNSS file and IGS product automatic acquisition, format conversion, file selection, data visualization, and analysis of GNSS observation files. It provides both a Windows form interface and a command shell interface for the Windows, Linux, or macOS operating system. Volunteers can also participate in and improve the software through GitHub. This software is continuing to evolve, improving its functionalities according to the updates introduced by the collaborators. We give a brief introduction to the software, including software architecture, functions, and modules. Lastly, we give several common examples, including parallel computing, visual satellite graphical display, and cycle slip detection, to show the working status of the current version of the software.

A wireless ranging system including six base stations and two observation stations was employed to monitor the surface displacement of an artificial landslide occurring in Nanjing Tangshan Town, southeast China, which was simulated by mechanical mining on a hill of artificial accumulation. The range data collected by both base stations and observation stations was devoted to construct observation. Moreover, the nonlinear least squares estimation method was used to obtain the displacement on account of nonlinearity in observation equation. Meanwhile, the DOP values derived from design matrix of observation equation was used to evaluate the spatial configuration of the base stations. The results from the wireless ranging system show that the occurrence of the artificial landslide was detected, and the trajectory of the landslide was showed through continuous observation. These findings demonstrate that the experimental design, wireless ranging system, as well as the displacement estimation algorithm can provide effective means to monitor and evaluate the status of landslides and unstable slope effectively in engineering applications.

Starting with Android 7.0, Google has opened APIs for smartphone users to obtain raw GNSS data, including pseudorange, carrier, and Doppler measurements. At present, the research of Android devices positioning based on original observations mostly focuses on GPS/GLONASS/Galielo, and there is few in-depth evaluation work on the data observation quality and positioning performance of BDS. In general, compared with traditional survey-grade GNSS receivers, observations of Android devices are not only affected by high measurement noise and multipath errors, but also by abnormalities such as duty cycle and phase error accumulation. Therefore, to improve the positioning accuracy of Android smartphones, the quality of the measured data and its influencing factors must be analyzed first. This article uses the Hisilicon Hi1103 positioning chip mounted on the HUAWEI Nova5 to evaluate the data quality and positioning performance of the BDS observation in a comprehensive perspective. The carrier-to-noise ratio, duty cycle, and measurement noise of different types of BDS satellites are evaluated and statistically analyzed. In static positioning performance assessment, the accuracy of SPP and PPP using BDS is evaluated using the positioning results of the measurement receiver. While in dynamic positioning performance assessment, because the accuracy of ordinary pseudo-range single point positioning is low, the author use an improved sliding window HATCH filter algorithm, which greatly improves the accuracy of dynamic positioning.

To obtain excellent comprehensive performances of the planar parallel manipulator for the high-speed application, an integrated optimal design method, which integrated dimensional synthesis, motors/reducers selection, and control parameters tuning, is proposed, and the 3RRR parallel manipulator was taken as the example. The kinematic and dynamic performances of condition number, velocity index, acceleration capability, and low-order frequency are taken into accounts for the dimensional synthesis. Then, to match motors/reducers parameters and keep an economical cost, the constraint equations and the parameters library are built, and the cost is chosen as one of the optimization objectives. Also, to get high tracking accuracy, the dynamic forward plus proportional–derivative control scheme is introduced, and the tracking error is chosen as one of the optimization objectives. Hence, the optimization model including dimensional synthesis, motors/reducers selection and controller parameters tuning is established, which is solved by the genetic algorithm II (NSGA-II). The result shows that comprehensive performances can be effectively promoted through the proposed integrated optimal design, and the prototype was constructed according to the Pareto-optimal front.

Due to the complex thermo-chemical-mechanical coupling during the curing and forming process of composite materials, spring-back is commonly observed after forming, which makes the shape of parts after curing and forming deviate from the design shape, resulting in difficult or even impossible assembly. In order to reduce the influence of the spring-back deformation on the forming, the finite element analysis software was used to analyze the curing deformation of the free-form composite part with foam filling, and the numerical simulation and analysis of the curing deformation of the complex curved parts were realized. The simulation analysis involves warping deformation under different angles and radii, which breaks through the unitary shape of previous research objects. In addition, the effect of foam on skin is also considered in the simulation process, and it is found that the shrinkage of the foam will affect the spring-back deformation of parts. Through finite element software, the spring-back simulation of multi-surface composite material after curing was carried out, and the results were compared with those obtained by digital measurement, the comparative analysis shows the effectiveness of the curing deformation prediction model in this paper.

Multivariable optimization under large data environment concerns with how to reliably obtain a set of optimization results from a mass of data that influence the object function complexly. This is an important issue in statistical calculation because the complexity between variable parameters leads to repeated statistical calculation analysis and a significant amount of data waste. A statistical multivariable optimization method using improved orthogonal algorithm based on large data is proposed. Considering the optimization problem with multi-parameters under large data environment, a multi-parameter optimization model used for improved orthogonal algorithm is established based on large data. Furthermore, an extensive simulation study on temperature field distribution of anti-/de-icing component was conducted to verify the validity of the statistical calculation analysis optimization method. The optimized temperature field distribution meets the anti-/de-icing requirements through numerical simul...

Global navigation satellite system real-time processing requires low latency, high timeliness, and high computational efficiency. A typical application is providing corrections using data from a regional Continuously Operating Reference Station (CORS) network. Usually the wide-lane and narrow-lane fractional cycle biases (FCBs) are determined at the server and broadcast to users to fix undifferenced ambiguity. Also, a tropospheric model is established at the server and broadcast to users to obtain accurate and reliable a priori zenith total delays for precise point positioning (PPP) using the ionospheric-free (IF) observation combination. Currently, serial methods are typically applied, i.e., all reference stations are involved in estimating the wide-lane and narrow-lane FCBs and establishing a regional tropospheric delay model. To improve the efficiency and shorten the latency, we develop a parallel computation method for regional CORS network corrections based on IF PPP by adopting a multicore parallel computing technology task parallel library, wherein parallel computations involving the FCBs, tropospheric delays, and tropospheric model are successively performed based on data parallelism, in which the same operation is performed concurrently on elements in an array, and task parallelism, which refers to one or more independent tasks running concurrently. Data covering four seasons from the Hong Kong and southwestern America CORS networks are utilized in the experiment. The single differenced FCBs between satellites are determined within each full pass, and a tropospheric model with an internal accuracy better than 1.4 cm and an external accuracy better than 1.6 cm is derived at the server. With the parallel implementation, the speedup ratios of FCB estimation and tropospheric modeling are 1.79, 3.15, 5.59, and 9.69 times higher for dual-core, quad-core, octa-core, and hexadeca-core platforms, respectively, than for a single-core platform.

Currently, the precise positions of seafloor control points are very important for expanding marine navigation activities. Equipped with a variety of sensors, a survey vessel measures and integrates heterogeneous data to obtain the coordinates of seafloor control points. However, the existence of time error factors such as inconsistent sampling intervals or signal transmission delays will cause time mismatches in multisource time series data. This will greatly reduce the positioning accuracy of seafloor control points. Previous studies have generally ignored the problem of time registration. To address this issue, this paper first briefly introduces the basic principle of positioning a single seafloor control point by using multiple types of sensors. The influences of various time errors on the resolution are analyzed through formula derivations and simulation experiments. Then, a robust constrained Kalman filter (RCKF) algorithm considering time registration is proposed. Based on the Kalman filter algorithm, the RCKF method takes the transmission delay error as a parameter and introduces priori constraints and the robust estimation. So the time registration and the determination of the seafloor control point coordinates are carried out in real time. The performance of the RCKF method in the designed simulation experiment and a testing experiment near Jiaozhou Bayou is discussed. The positioning accuracy is 3.07 cm in simulation when adopting the RCKF method, which is better than other comparison methods. The positioning accuracy of the testing results can be greatly improved from 1.348 m in the common method to 0.12 m based on the RCKF method. The results show that the newly proposed method ensures the consistency of multisource time series and has good stability and accuracy in positioning a single seafloor control point.

A novel anti/de-icing system combining heat expansion film and electric heating for helicopter rotor based on composite materials has been developed. The device is installed on the surface of the helicopter rotor icing area, which main parts include: rotor skin, electric anti/de-icing system, heat expansion film anti/de-icing system and icing sensor used to detecting ice thickness of rotor. Heat expansion film anti/de-icing system includes heating expansion film, check valve, air compressor that used in the engine bleed air and inflating the expansion film, pump that used to close the heat expansion of film, pressure gauge, hot gas pipelines and icing sensors; Electrical anti/de-icing system includes heating wire pads, heat transfer layer, heat insulation layer, voltage switch that used to adjust the heating intensity, multi-channel controller that used to control the different series of heating pad and icing sensor used to detect rotor icing thickness. In this paper, the simulation results present that the innovation anti-de icing system can effectively detect and prevent icing on helicopter rotor in real time and the anti-de icing work can be done in a short time, low energy consumption and thoroughly. The invention can meet the anti-de icing requirements in various bad weather conditions and different freezing conditions.

Considering the multivariable influence on the temperature field of anti-icing component, a numerical simulation model coupling multi-field for helicopter rotor anti-icing composite structure component under big data environment was presented. The multi-parameters were the main influencing factors in heat transfer numerical simulation. Convective heat transfer and heat conduction coupling was analysis for temperature field of anti-icing component. The traditional orthogonal design method was used as optimization program for analyzing of temperature field optimization of composite material for anti-icing structure. The temperature field distribution of the iron surface after optimization meets the requirements of the relevant anti-icing parameters. Thus, based on the big data environment, the optimization effect of the parameters of the rotor anti-icing component is more ideal. The average temperature and high temperature distribution change after optimization indicate that the optimized anti-icing effect is more evident than the original anti-icing effect which means the optimization performs well.

In this paper, a novel adaptive control for dual-arm cooperative manipulators is proposed to accomplish the hybrid position/force tracking in the presence of dynamic and closed-chain kinematic uncertainties. Self-convergent parameter estimation of the grasped object's centre of mass and contact force estimation are incorporated into this systematic scheme. Moreover, internal force and contact force tracking objectives are achieved simultaneously by incorporating into the position tracking formula with proper null-space projection and rotation transformation. Noisy force derivative signals are not required. This adaptive controller is mathematically derived based on Lyapunov stability analysis. Three sets of simulations corresponding to three different situations are presented to verify the effectiveness and superiority of the proposed controller.

In order to figure out stall solution of induced draft fans (IDFs) in power plants, the stall reason of IDFs with guide vanes in Tongchuan Power Plant of 600MW is investigated. By comparing hot test data of IDFs, we also find that the IDFs are of low efficiency and high power consumption in addition to the stall problem. Considering the above condition of the IDFs, two reasonable approaches are proposed to prevent stall and reduce power consumption of IDFs. With the hot test of reformation results, it is found that the reformation scheme of IDFs with adjustable rotor blades is much better with higher efficiency and safer characteristics. The work in this study has great significance and also provides practicable ways for stall-preventing, energy-saving and cost-reducing of power plants.

A numerical optimization method of helicopter rotor composite material anti-/de-icing component based on big data analytics was proposed. Considering the uneven distribution problem of the temperature field on the iron surface of the rotor composite material anti-/de-icing component, the multi-parameter heat transfer numerical simulation model of the rotor composite material anti-/de-icing component was established based on big data analytics. The environment of the composite material anti-/de-icing component was simplified. Linear heat conduction temperature field optimization method was proposed. The optimization program was determined by using orthogonal test method combined with the composite material anti-/de-icing component multi-parameter model. The optimized temperature field distribution on the iron surface of the composite material anti-/de-icing component meets the anti-/de-icing requirements through the finite element numerical simulation based on big data analytics of the rotor composite material anti-/de-icing component. Thus, the temperature field numerical simulation of the rotor composite material anti-/de-icing component with multi-parameter under a big data environment is effectively achieved. Simulation results show that the optimization effect is more evident than the non-optimized temperature distribution with the optimized results of the proposed method. Results verify the effectiveness of the proposed method.