Performance analysis of real-time and post-mission kinematic precise point positioning in marine environments

This article focuses on the performance analysis of both real-time and post-mission kinematic precise point positioning(PPP)in challenging marine environments.For this purpose,a real dynamic experiment lasting 6 h was carried out on a lake dam in?orum City of Turkey.While the kinematic test was continuing,the real-time PPP coordinates were obtained for each measurement epoch with a commercial real-time PPP(RT-PPP)service,namely the Trimble Center Point RTX.Then the post-mission PPP(PM-PPP)coordinates were calculated by using Multi-GNSS data and the Multi-GNSS Experiment(MGEX)precise products.The kinematic RT-PPP and PM-PPP results showed that the PPP coordinates were consistent with the relative solution at centimetre and decimetre level in horizontal and height components,respectively.This study implies that PPP technique is a powerful tool for highly accurate positioning in both real-time and post-mission modes,even for dynamic applications in harsh environments.

A Mixed Real-time Algorithm for the Forward Kinematics of Stewart Parallel Manipulator

Aimed at the real-time forward kinematics solving problem of Stewart parallel manipulator in the control course, a mixed algorithm combining immune evolutionary algorithm and numerical iterative scheme is proposed. Firstly taking advantage of simpleness of inverse kinematics, the forward kinematics is transformed to an optimal problem. Immune evolutionary algorithm is employed to find approximate solution of this optimal problem in manipulator＇s workspace. Then using above solution as iterative initialization, a speedy numerical iterative scheme is proposed to get more precise solution. In the manipulator running course, the iteration initialization can be selected as the last period position and orientation. Because the initialization is closed to correct solution, solving precision is high and speed is rapid enough to satisfy real-time requirement. This mixed forward kinematics algorithm is applied to real Stewart parallel manipulator in the real-time control course. The examination result shows that the algorithm is very efficient and practical.

Kinematically Aligned Total Knee Arthroplasty for Valgus Osteoarthritis of More than 10°―Is It Still a “Challenging Surgery”?

Mechanically aligned total knee arthroplasty (TKA) for valgus knee is considered a “challenging surgery.” Recently, the kinematic alignment (KA) method has gained attention. This study aimed to present objective clinical data, such as intraoperative balance assessment and radiographic evaluation of postoperative lower extremity alignment after TKA using the KA method for valgus deformity. Twenty-one TKA knees (mean age, 74 years;2 males, 19 females) with KA for severe valgus deformity (hip-knee-ankle-angle ≥ 10°) performed at our department in the past 3 years were included in this study. Intraoperative gap and balance measurements and postoperative radiographic evaluation were performed. A total arc of range of motion was achieved up to 98% of preoperative values at 3 weeks postoperatively. Intraoperative gap and balance were stable throughout the entire range of motion. In addition, there were no statistically significant differences in either balance or gap values at each flexion angle. KA TKA is a “simple surgery” rather than a “challenging surgery” because additional soft tissue procedures are not required, operative time is short, intraoperative and postoperative balance is very stable, and a good alignment is achieved. This procedure may relieve surgeons of the stress of TKA for valgus deformities.

Measurement on Morphology and Kinematics of Crucian Vertebral Joints

In order to provide data for joints control of our recently designed crucian hke biomlmetlc robot fish, an A-ray photograph technology was adopted to determine the number and length of vertebral joints. A frame-by-frame analysis of high-speed videotapes was conducted to quantify the kinematics of crucian at four speeds （12.651 cm·s^-1, 18.201 cm·s^-1, 21.901 cm·s^-1, 24.368cm·s^-1） during cruising. In addition to a brief introduction to experimental conditions and methods, we analyzed the influence of individual diversity on the absolute length as well as the non-dimensional length of vertebral joints. We also presented the maximal angular velocity and acceleration of vertebral joints under four swimming speeds, and provided the change of relative rotation angle, angular difference, angular velocity and angular acceleration of the rear vertebral joints with time at a certain swimming speed of 12.651 cm·s^-1. At last, we presented the maximal lateral displacement of each mark at that speed. The study found that the influence of individual diversity on the non-dimensional length of vertebral joints is not significant; the maximal angular velocity and acceleration of vertebral joints increase with swimming speed; angular difference, angular velocity and angular acceleration exhibit two maximal values over one period at a certain swimming speed.

Model-based framework for multi-axial real-time hybrid simulation testing

Real-time hybrid simulation is an efficient and cost-effective dynamic testing technique for performance evaluation of structural systems subjected to earthquake loading with rate-dependent behavior. A loading assembly with multiple actuators is required to impose realistic boundary conditions on physical specimens. However, such a testing system is expected to exhibit significant dynamic coupling of the actuators and suffer from time lags that are associated with the dynamics of the servo-hydraulic system, as well as control-structure interaction （CSI）. One approach to reducing experimental errors considers a multi-input, multi-output （MIMO） controller design, yielding accurate reference tracking and noise rejection. In this paper, a framework for multi-axial real-time hybrid simulation （maRTHS） testing is presented. The methodology employs a real-time feedback-feedforward controller for multiple actuators commanded in Cartesian coordinates. Kinematic transformations between actuator space and Cartesian space are derived for all six-degrees-of- freedom of the moving platform. Then, a frequency domain identification technique is used to develop an accurate MIMO transfer function of the system. Further, a Cartesian-domain model-based feedforward-feedback controller is implemented for time lag compensation and to increase the robustness of the reference tracking for given model uncertainty. The framework is implemented using the 1/5th-scale Load and Boundary Condition Box （LBCB） located at the University of Illinois at Urbana- Champaign. To demonstrate the efficacy of the proposed methodology, a single-story frame subjected to earthquake loading is tested. One of the columns in the fraane is represented physically in the laboratory as a cantilevered steel column. For real- time execution, the numerical substructure, kinematic transformations, and controllers are implemented on a digital signal processor. Results show excellent performance of the maRTHS framework when six-degrees-of-freedom are controUed at the interface between substructures.

Pseudo-static/dynamic solutions of required reinforcement force for steep slopes using discretization-based kinematic analysis

This paper presents a procedure for assessing the reinforcement force of geosynthetics required for maintaining dynamic stability of a steep soil slope. Such a procedure is achieved with the use of the discretization technique and kinematic analysis of plasticity theory, i.e. discretization-based kinematic analysis. The discretization technique allows discretization of the analyzed slope into various components and generation of a kinematically admissible failure mechanism based on an associated flow rule.Accordingly, variations in soil properties including soil cohesion, internal friction angle and unit weight are accounted for with ease, while the conventional kinematic analysis fails to consider the changes in soil properties. The spatialetemporal effects of dynamic accelerations represented by primary and shear seismic waves are considered using the pseudo-dynamic approach. In the presence of geosynthetic reinforcement, tensile failure is discussed providing that the geosynthetics are installed with sufficient length. Equating the total rates of work done by external forces to the internal rates of work yields the upper bound solution of required reinforcement force, below which slopes fail. The reinforcement force is sought by optimizing the objective function with regard to independent variables, and presented in a normalized form. Pseudo-static analysis is a special case and hence readily transformed from pseudodynamic analysis. Comparisons of the pseudo-static/dynamic solutions calculated in this study are highlighted. Although the pseudo-static approach yields a conservative solution, its ability to give a reasonable result is substantiated for steep slopes. In order to provide a more meaningful solution to a stability analysis, the pseudo-dynamic approach is recommended due to considerations of spatial etemporal effect of earthquake input.

Comparative study on efficacy of three sperm-separation techniques

Aim: To evaluate the comparative effectiveness of real-time sperm separation technique (Wang's tube method) andother two conventional methods in isolating high-quality sperm preparation, and to compare the spouse pregnancy ratein intrauterine insemination (IUI) with sperm preparations isolated by these methods. Methods: The effectivenessof the real-time sperm separation technique, the conventional swim-up and the Percoll discontinuous density gradientmethods in isolating sperm preparations from 60 infertile patients (20 with apparently normal semen and 40, abnormalsemen contaminated with microorganisms and other impurities) was evaluated and compared. The microorganisms to beremoved included bacteria, vires, Chlamydia trachomaticum, Ureaplsama urealyticum, etc. The spouse pregnancyrates in IUI with sperm preparations isolated by these three techniques from 80 oligoasthenoteratospermic patients werealso compared. Results: The quality (including the percentages of normal form, normal-chromatin and motilesperm, and the grade of motility) of sperm obtained by the real-time sperm separation technique was much higher ( P< 0.01) as compared with those by the other two methods. The Wang's tube method was also more effective in remov-ing microorganisms and other impurities. The method provided a higher IUI pregnancy rate than the other two spermseparation techniques ( P < 0.05). Conclusion: The real-time sperm separation technique is the most effectivemethod so far available in isolating high-quality sperm samples to be used in assisted reproduction.

Explicit Symplectic Geometric Algorithms for Quaternion Kinematical Differential Equation

Solving quaternion kinematical differential equations(QKDE) is one of the most significant problems in the automation, navigation, aerospace and aeronautics literatures. Most existing approaches for this problem neither preserve the norm of quaternions nor avoid errors accumulated in the sense of long term time. We present explicit symplectic geometric algorithms to deal with the quaternion kinematical differential equation by modelling its time-invariant and time-varying versions with Hamiltonian systems and adopting a three-step strategy. Firstly,a generalized Euler's formula and Cayley-Euler formula are proved and used to construct symplectic single-step transition operators via the centered implicit Euler scheme for autonomous Hamiltonian system. Secondly, the symplecticity, orthogonality and invertibility of the symplectic transition operators are proved rigorously. Finally, the explicit symplectic geometric algorithm for the time-varying quaternion kinematical differential equation, i.e., a non-autonomous and non-linear Hamiltonian system essentially, is designed with the theorems proved. Our novel algorithms have simple structures, linear time complexity and constant space complexity of computation. The correctness and efficiencies of the proposed algorithms are verified and validated via numerical simulations.

Development of a Microcomputer System for 3D Kinematic Simulation

Software system is developed for real-time processing of 3D graphics by Visual C + + calling functions in PpenGL under the environment of Windows NT(Windows 95). By 3D modeling after mathematics modeling automatic generation of 3D soid and real-time processing of 3D animaation are realized, and a microcomputer system is developed for real-time kinematic simulation.

Coronal Alignment of Three Different Types of Implants in Kinematically Aligned Total Knee Arthroplasty: A Comparative Study

Background: The number of total knee arthroplasty (TKA) surgeries performed each year is increasing worldwide and mechanical alignment (MA) is currently seen as the gold standard procedure. However, taking neutral alignment as the universal goal may be mistaken. In our hospital, we currently conduct kinematically aligned TKA (KA-TKA). Three different types of implants are used: the cruciate-retaining (CR) type, cruciate-sacrificing (CS) type, or bi-cruciate-retained (BCR) type. We aimed to compare the coronal alignment observed following KA-TKA and MA-TKA and in normal knees, as well as that achieved with different types of implants. Methods: The study comprised 206 knees of Japanese patients who underwent KA-TKA using varying implants in our Hospital between May 2019 and April 2020. Measurements of pre- and postoperative coronal alignment were determined from weight-bearing full-leg standing radiographs. The postoperative results were compared to measurements taken from patients who underwent MA-TKA (N = 96) and normal knees (N = 60). Results: No significant differences between the KA-TKA group and normal knees were found for the medial proximal tibial angle (MPTA) (–4.2° ± 2.6° vs –3.8° ± 2.5°) or joint line orientation angle (JLOA) (0.2° ± 1.9° vs 0.3° ± 1.4°). However, when MA-TKA was compared to KA-TKA and normal knees, there were significant differences in both the MPTA and JLOA (p < 0.01). Furthermore, for the different implant types, MPTA exhibited significantly greater varus alignment when a CS-type was used than with the other two. Conclusions: Here, we demonstrated that following KA-TKA, the articular surface of the tibia exhibited a similar varus alignment as that of normal knees, meaning that the technique reproduces the native knee. Furthermore, KA is patient-specific, and does not have the same failures as MA-TKA. Therefore, we anticipate a paradigm shift from mechanical to kinematic alignment, which may help reduce the dissatisfaction rate of TKA patients.

Kinematic properties of the dual AGN system J0038+4128 based on long-slit spectroscopy

The study ofkiloparsec-scale dual active galactic nuclei （AGN） provides important clues for understanding the co-evolution between host galaxies and their central supermassive black holes undergoing a merging process. We present long-slit spectroscopy of J0038 ＋4128, a kiloparsec-scale dual AGN candidate, discovered recently by Huang et al., using the Yunnan Faint Object Spectrograph and Camera （YFOSC） mounted on the Lijiang 2.4-m telescope administered by Yunnan Observatories. From the long-slit spectra, we find that the average relative line-of-sight （LOS） velocity between the two nuclei （J0038＋4128N and J0038＋4128S） is about 150 km s-1. The LOS velocities of the emission lines from the gas ionized by the nuclei activities and of the absorption lines from stars governed by the host galaxies for different regions of J0038＋4128 exhibit the same trend. The same trend in velocities indicates that the gaseous disks are co-rotating with the stellar disks in this ongoing merging system. We also find several knots/giant H II regions scattered around the two nuclei with strong star formation revealed by the observed line ratios from the spectra. Those regions are also clearly detected in images from HST F336W/U-band and HST F555W/V-band.

我国优秀女子高尔夫球员短杆挥杆技术运动学分析

目的:探究中国优秀女子高尔夫球员的短杆挥杆技术特征,为高尔夫球项目的科学化训练提供理论支持。方法:采用三维高帧录像解析法,对比赛过程中的12名中国优秀女子职业球员长草区短杆挥杆动作进行拍摄分析。研究结果:①挥速(32.42±6.27 km/h)与球速(32.23±4.96 km/h)均值相近,水平飞行距离与挥速、球速呈正相关(p<0.05),起飞角度与水平飞行距离负相关(p<0.05)。②上挥杆阶段的右髋角变化量与水平飞行距离正相关(p<0.05)。③上杆顶点时,在额状面上髋转动幅度分别与起飞角度、水平飞行距离、滚动距离及站位宽度皆呈负相关(p<0.05)。④下挥杆用时(0.28±0.03s)与送杆用时(0.29±0.09s)相近,下挥杆用时约为上挥杆用时(0.68±0.10s)的1/2。研究结论:①挥速与球速均值相近,在实际短杆击球环境下杆头速度不能完全转化为球速。②上挥杆阶段,减少右肩、右肘和右腕角度是提高挥速、球速有效方式。此阶段,增大髋向右转动幅度可有效增加水平飞行距离。③站位宽度减少,有利于上挥杆阶段重心上移幅度减少,进而增加起飞角度。

Clinical significance and influencing factors of linked color imaging technique in real-time diagnosis of active Helicobacter pylori infection

Background:Determining the Helicobacter pylori (H. pylori) infection state during the gastroscopic process is important but still challenging. The linked color imaging (LCI) technique might emphasize the mucosal color change after H. pylori infection, which might help the diagnosis. In the present study, we aimed to compare the LCI technique with traditional white light imaging (WLI) endoscopy for diagnosing active H. pylori infection.Methods:We collected and analyzed gastroscopic images from 103 patients in our hospital from November 2017 to March 2018, including both LCI and WLI modes. All images were randomly disordered and independently evaluated by four endoscopists who were blinded to the H. pylori status of patients. In addition, the H. pylori state was determined by both rapid urease test and pathology staining. The sensitivity, specificity, positive prediction value (PPV), and negative prediction value (NPV) were calculated for the detection of H. pylori infection. Moreover, the kappa value and interclass correlation coefficient (ICC) were used to evaluate the inter-observer variety by SPSS 24.0 software.Results:Of the 103 enrolled patients, 27 of them were positive for H. pylori infection, while the 76 patients were negative. In total, 388 endoscopic images were selected, including 197 WLI and 191 LCI. The accuracy rate for H. pylori evaluation in the corpus LCI group was significantly higher than other groups (81.2% vs. 64.3%-76.5%, χ2 = 34.852, P < 0.001). Moreover, the corpus LCI group had the optimal diagnostic power with the sensitivity of 85.41% (95% confidence interval [CI]: 76.40%-91.51%), the specificity of 79.71% (95% CI: 74.38%-84.19%), the PPV of 59.42% (95% CI: 50.72%-67.59%), and the NPV of 94.02% (95% CI: 89.95%-96.56%), respectively. The kappa values between different endoscopists were higher with LCI than with WLI (0.433-0.554 vs. 0.331-0.554). Consistently, the ICC value was also higher with LCI than with WLI (0.501 [95% CI: 0.429-0.574] vs. 0.397 [95% CI: 0.323-0.474]). We further analyzed the factors that might lead to misjudgment, revealing that active inflammation might disturb WLI judgment (accuracy rate: 58.70% vs. 76.16%, χ2 = 21.373, P < 0.001). Atrophy and intestinal metaplasia might affect the accuracy of the LCI results (accuracy rate: 66.96% vs. 73.47%, χ2 = 2.027;68.42% vs. 73.53 %, χ2 = 1.594, respectively);however, without statistical significance (P = 0.154 and 0.207, respectively).Conclusions:The application of LCI at the corpus to identify H. pylori infection is reliable and superior to WLI. The inter-observer variability is lower with LCI than with WLI.

Low-cost experimental application of real-time kinematic positioning for increasing the benefits in cereal crops

Traditional agriculture is facing several challenges worldwide such as increased population growth,rapid forestry and urbanization,resource scarcity,climate change,environmental pollution,competition among different markets.Hence,farmers need to improve productivity in order to maintain the output level.This study attempted to evaluate the benefits of using Real-Time Kinematic(RTK)positioning in precision agriculture through a series of real measurements carried out when farming cereals.All farming management actions involved in the cereal crop process(raise fallow,plow,sow,fertilize,mow,and harvest)have been done using an automatic guidance system that has reduced costs.A reduction of 20%has been quantified in the fuel,the amount of fertilizer,the labor costs and the hours of work.Consequently,the environmental impact has been also reduced.An inexpensive system consisting of a reference base station near the field and a mobile unit mounted on the test vehicle has been installed in order to increase the benefits in cereal crops.Global Navigation Satellite System(GNSS)systems including Global Positioning System(GPS),GLONASS,Galileo and Beidou have been used in the analysis.This research serves as a practical guide to implementing a low-cost guidance system to achieve best management practice.

Applying Global Positioning System Real-Time Kinematic Technology to Collection and Analysis of Rowing Information

To obtain higher accuracy of information concerning boat motion, the use of global positioning system (GPS) real-time kinematic (RTK) technology was investigated. Through RTK technology, a measurement precision of the ±1 cm range can be achieved. The research equipment included a GPS receiver and a personal digital assistant as a data control and processing unit. Real-time GPS data was captured and processed to acquire various parameters, including the boat track, velocity curve, stroke rate, and stroke distance. Using this data, the quantitative information related to rowing training can be achieved. The results are helpful for analyzing the biomechanical parameters of rowing techniques and for evaluating training efficiency.

Squat motion of a bipedal robot using real-time kinematic prediction and whole-body control

Squatting is a basic movement of bipedal robots,which is essential in robotic actions like jumping or picking up objects.Due to the intrinsic complex dynamics of bipedal robots,perfect squatting motion requires high-performance motion planning and control algorithms.The standard academic solution combines model predictive control(MPC)with whole-body control(WBC),which is usually computationally expensive and difficult to implement on practical robots with limited computing resources.The real-time kinematic prediction(RKP)method is proposed,which considers upcoming reference motion trajectories and combines it with quadratic programming(QP)-based WBC.Since the WBC handles the full robot dynamics and various constraints,the RKP only needs to adopt the linear kinematics in the robot's task space and to softly constrain the desired accelerations.Then,the computational cost of derived closed-form RKP is greatly reduced.The RKP method is verified in simulation on a heavy-loaded bipedal robot.The robot makes rapid and large-amplitude squatting motions,which require close-to-limit torque outputs.Compared with the conventional QP-based WBC method,the proposed method exhibits high adaptability to rough planning,which implies much less user interference in the robot's motion planning.Furthermore,like the MPC,the proposed method can prepare for upcoming motions in advance but requires much less computation time.

Real-time and dynamic transduction technique for simultaneous detection of O_2 and CO_2

OXYGEN and carbon dioxide are the coexistent gases closely related to life processes. In our pre-

中日优秀女子高尔夫球员刘钰与畑冈奈纱一号木杆技术三维运动学对比分析

目的:对比分析刘钰与畑冈奈纱一号木技术动作,揭示二人的技术特点和存在问题,为我国女子高尔夫球员一号木杆技术的训练提供参考。研究方法:采用文献资料法、实地考察法、三维录像拍摄法、录像解析法和数理统计法,对二人的一号木技术进行对比分析。结果:①刘钰和畑冈奈纱的最快杆头速度分别为105.83 mph、105.78 mph,球速分别为147.28 mph、144.13 mph;二人的球落点分别为254.5码和241码、起飞角度分别为12.3°和11.6°,二人的停球距离均为269.5码。②上杆过程中,畑冈奈纱的髋转动角度、肩转动角度和肩髋相对转动角度均大于刘钰。③上杆过程中刘钰重心前移,而畑冈奈纱重心后移;下杆过程中,刘钰重心前后移动的幅度较畑冈奈纱大,而重心从右至左移动的幅度较小;在下杆第2阶段,刘钰的重心高度较稳定,而畑冈奈纱的重心向上移动距离较大。结论:①刘钰在上杆过程中过快的杆头速度,不利于保持上杆顶点身体的稳定性;在下杆过程中刘钰的平均加速过程较为一致,应进行优化训练。②刘钰在上杆过程中肩髋相对转动不足,下杆过程中髋转动较多,但肩转动较少,对其改进可能会提升杆头速度。③刘钰在上杆过程中的重心前移较多,下杆过程中前后移动幅度较大,可能会造成击球不稳定;下杆过程中从右至左的移动幅度较小,不利于杆头速度的提升;在下杆第2阶段刘钰的重心上下保持稳定,而畑冈奈纱利用重心升高来提升杆头速度,弥补了身高不足的劣势。

基于机器学习的速度攀岩关键技术动作指标筛选

背景:筛选关键动作技术指标用以指导专项训练或比赛是提升比赛成绩的关键。男、女运动员动作技术差异明显,男、女运动员的关键动作技术指标尚未可知。目的:筛选影响速度攀岩精英运动员比赛成绩的关键动作技术指标,为速度攀岩的科学训练提供方向与理论支撑。方法:选用2017-2021年间攀岩世锦赛、世界杯和中攀联赛中速度攀岩决赛视频,获取男、女前4名运动员的比赛样本(男子:109个,女子:117个),运用二维运动学分析法,采集运动员的反应时、触点特征和分段速度指标,分别建立男子与女子速度攀岩精英运动员的随机森林和XGBoost回归模型,计算各动作技术指标对比赛成绩影响力。结果与结论:①男子精英运动员的随机森林和XGBoost模型的均方根误差分别为0.224与0.265,r2分别0.765与0.686;关键动作技术指标为:左手触点时间总和、右手动作频率、右手触点时间总和、3-6号点速度、左脚动作频率、右脚触点时间总和、11-13号点速度、13-18号点速度、8-10号点速度、左脚触点时间总和、左手触点个数和右脚动作频率;②女子精英运动员的随机森林和XGBoost模型的均方根误差分别为0.066与0.055,r2分别为0.846与0.887;关键动作技术指标为:左手触点时间总和、右手触点时间总和、右手动作频率、左脚动作频率、左脚触点时间总和、8-10号点速度、右脚触点时间总和、10-11号点速度和13-18号点速度;③速度攀岩比赛上肢动作技术指标(触点时间总和与动作频率)的影响力高于下肢动作技术指标,触点个数对比赛成绩影响力不高,男子与女子精英运动员首要制胜段落分别为3-6与8-11号点段落。运动员应重点优化首要制胜段落的上肢触点时间,带动优化下肢触点时间指标,提升比赛成绩。