bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further Results on Performance Guarantees in Adaptive Control of Uncertain Systems With Unmodeled Dynamics
Authors: Dogan K. Merve , Yucelen Tansel , Muse Jonathan A. 
Published: January 2021

Abstract
Adaptive control approaches are effective system-theoretical methods for guaranteeing both the stability and the performance of physical systems subject to uncertainties. However, the stability and performance of these approaches can be severely degraded by the presence of unmodeled dynamics. Motivated by this standpoint, the previous work of the authors introduced a model reference adaptive control architecture based on the direct uncertainty minimization method for systems with additive input uncertainties and unmodeled dynamics. In particular, the proposed approach not only guaranteed the closed-loop stability predicated on a sufficient stability condition but also improved the closed-loop performance. The purpose of this paper is to generalize this previous work of the authors. Specifically, a model reference adaptive control architecture is given and it is system-theoretically analyzed for systems with unmodeled dynamics, and both additive input and control effectiveness uncertainties (we refer to Theorems 1 and 2 of this paper). The sufficient stability condition of the resulting architecture relies on linear matrix inequalities and this architecture can be effective in achieving not only stability but also a desired level of closed-loop system performance. Finally, we also provide an illustrative numerical example, which demonstrates the given theoretical results. (This research was supported by the Air Force Research Laboratory Aerospace Systems Directorate under the Universal Technology Corporation Grant 162642-20-25-C1.)
Stability Analysis and Controller Design for Linear Time Periodic Systems Using Normal Forms
Authors: Subramanian Susheelkumar C. , Redkar Sangram 
Published: January 2021

Abstract
The investigation of stability bounds for linear time periodic systems have been performed using various methods in the past. The Normal Forms technique has been predominantly used for analysis of nonlinear equations. In this work, the authors draw comparisons between the Floquet theory and Normal Forms technique for a linear system with time periodic coefficients. Moreover, the authors utilize the Normal Forms technique to transform a linear time periodic system to a time-invariant system by using near identity transformation, similar to the Lyapunov Floquet (L-F) transformation. The authors employ an intuitive state augmentation technique, modal transformation and near identity transformations to enable the application of time independent Normal Forms directly without the use of detuning or book-keeping parameter. This method provides a closed form analytical expression for the state transition matrix with the elements as a function of time. Additionally, stability analysis is performed on the transformed system and the resulting transitions curves are compared with that of numerical simulation results. Furthermore, a linear feedback controller design is discussed based on the stability bounds and the implementation of an effective feedback controller for an unstable case is discussed. The theory is validated and verified using numerical simulations of temporal variation of a simple linear Mathieu equation.
Attack-Resilient Observer Pruning for Path-Tracking Control of Wheeled Mobile Robot
Authors: Zheng Yu , Anubi Olugbenga Moses 
Published: January 2021

Abstract
Path-tracking control of wheeled mobile robot (WMR) has gained a lot of research attention, primarily because of its wide applicability — for example intelligent wheelchairs, exploration-assistant remote WMR. Recent increase in remote and autonomous operations/requirements for WMR has led to more and more use of IoT devices within the control loop. Consequently, providing interfaces for malicious interactions through false data injection attacks (FDIA). Moreover, optimization-based FDIAs have been shown to cause catastrophic consequences in feedback control systems while by-passing any residual-based monitoring system. Since these attacks target system measurement process, this paper focuses on the problem of improving the resiliency of dynamical observers against FDIA. Specifically, we propose an attack-resilient pruning algorithm which attempts to exclude compromised channels from being processed by the observer. The proposed pruning algorithm improves attack-localization precision to 100% with high probability, which correspondingly improves the resiliency of the underlying UKF to FDIA. The improvements due to the developed resilient pruning-based observer is validated through a numerical simulation of a two-layer path-tracking control platform of differential-driven wheeled mobile robot (DDWMR) under FDIA.
Simultaneous Vibration Mitigation and Energy Harvesting for a Nonlinear Oscillator
Authors: Kakou Paul , Barry Oumar 
Published: January 2021

Abstract
Considerable attention has been recently given to electromagnetic resonant shunt tuned mass damper-inerter (EH-TMDI) for simultaneous vibration mitigation and energy harvesting. However, only linear structures have been investigated. Hence, in this paper, we aim at simultaneously achieving vibration mitigation and energy harvesting for nonlinear oscillators. To do so, we attach a nonlinear electromagnetic resonant shunt tuned mass damper-inerter (NEH-TMDI) to a single degree of freedom nonlinear oscillator (Duffing Oscillator). The nonlinear oscillator is coupled to the tuned mass damper via a linear and a nonlinear spring. Both the electromagnetic and the inerter devices are grounded on one side and connected to the nonlinear vibration absorber on the other side. This is done so to relax the trade off between energy harvesting and vibration suppression. The electromagnetic transducer is shunted to a resistor-inductor circuit. The governing equations of motion are derived using Newton’s method. Numerical simulations are carried out to examine the performance of the proposed NEH-TMDI. Comprehensive parametric analyses are conducted to identify the key design parameters that render the best performance of the NEH-TMDI. The results show that selected parameters offer regions were maximum energy dissipated and maximum energy harvested coincide. The findings are very promising and open a horizon of future opportunities to optimize the design of the NEH-TMDI for superior performance.
Predictive Motion Planning for Autonomous Vehicles With Geometric Constraints via Convex Optimization
Authors: Zhu Xiaoyuan , Chen Jian , Ma Yan , Deng Jianqiang , Wang Yuexuan 
Published: January 2021

Abstract
In this paper, we propose an MPC-based motion planning algorithm, including a decision-making module, an obstacle-constraints generating module, and an MPC-based planning module. The designed decision module effectively distinguishes between structured and unstructured roads and processes them separately, so that the algorithm is more robust in different environments. Besides, the movement of obstacles is considered in the decision-making and obstacle constraints generating module. By processing obstacles with lateral and longitudinal speed separately, obstacle avoidance can be done in scenarios with moving obstacles, including moving obstacles crossing the road. Instead of treating the vehicle as a mass point, we explicitly consider the geometric constraints by modeling the vehicle as three intersecting circles when generating obstacle constraints. This ensures that the vehicle is collision-free in motion planning, especially when the vehicle turns. For non-convex obstacle constraints, we propose an algorithm that generates up to two alternative linear constraints to convexify the obstacle constraints for improving computational efficiency. In MPC, we consider the vehicle kino-dynamic constraints and two generated linear constraints. Therefore, the proposed method can achieve better real-time performance and can be applied to more complicated traffic scenarios with moving obstacles. Simulation results in three different scenarios show that motion planning can achieve satisfactory performance in both structured and unstructured roads with moving obstacles.
Effect of Neural Network on Reduction of Noise for Edge Detection
Authors: Zhang Enqi , Peters Diane L. , Zhang James Z. 
Published: January 2021

Abstract
Processing photographic images is important in many applications, among them the development of automated driver assistance systems (ADAS) and autonomous vehicles. Many techniques are used for processing images, including neural networks, other types of machine learning, and edge detection. One common issue with processing these photos is the presence of noise, whether caused by the camera itself or by physical conditions (e.g., weather conditions or dirt on road signs). In this paper, a neural network is used for noise reduction to improve edge detection results and tested with two kinds of noise, Gaussian and salt & pepper noise, and three different edge detection algorithms, Canny, Sobel, and Zhang. Results showed that the noise reduction process was effective in improving performance of the edge detection process, with the exception of conditions where the noise was originally very minimal.
Dynamic Genetic Algorithm for Optimizing Movement of a Six-Limb Creature
Authors: Viaña Perez Javier , Scott Drew , Kumar Manish , Cohen Kelly 
Published: January 2021

Abstract
In this study we consider a Dynamic Genetic Algorithm used to optimize the movement of a symmetric six-legged creature. The optimal movement is that which advances the creature in a straight line forward with the greatest average speed. The mutation rate and crossover rate are adjusted based on number of iterations the algorithm has completed. This dynamic element was added to improve convergence rate as well as reducing the chance that the algorithm is stuck in a local optimum. The chromosomes are represented by a 2-dimensional array, where the rows represent sequences of movement. Each row defines the change in the angle for all the joints. Angular rates are restricted per joint, as well as ranges of motion. The fitness of a chromosome is determined by the resultant average speed, calculated as total displacement of the center of gravity over total time of movements in the chromosome. The results of this study show the possibility to breed mathematically the creature by using the Dynamic Genetic Algorithm proposed. This learning process converged, for all the simulations carried out, to the natural motion of six-legged beings like the ants.
Data-Driven Post-Filtering of Acoustics Noise in Atomic Force Microscope Imaging
Authors: Chen Jiarong , Zou Qingze 
Published: January 2021

Abstract
This paper presents a data-driven dynamics-based filtering approach to eliminate acoustic noise-caused distortion in images of atomic force microscope (AFM). AFM operations are sensitive to external noise as disturbances including acoustic noise as disturbances to the probe-sample interaction directly results in distortions in AFM imaging. Although conventional passive noise cancellation has been employed, limitation exists and residual noise still persists. Advanced online control techniques face difficulty in capturing the complex noise dynamic and limited system bandwidth imposed by the robustness requirement. Therefore, In this work, we propose a finite-impulse-response (FIR) based post-filtering approach to remove the noise-caused distortion in AFM images. Experimental implementation is presented and discussed to illustrate the proposed technique.
Continuum of Motion Equations and Control Laws for the Inverted Pendulum Cart and Rotary Pendulum
Authors: Lare Constance , White Warren N. 
Published: January 2021

Abstract
This paper questions whether the controller properties for a given rigid body mechanical system still apply as the given system is changed. As a first attempt in this investigation, the controller for the underactuated rotary pendulum is investigated as the system morphs into an underactuated inverted pendulum cart. As the limiting condition of the inverted pendulum cart is approached, the investigation allows the controller to also morph. The authors show that, as the pendulum base radius grows, the rotary pendulum equations of motion morph into the inverted pendulum cart dynamics. The paper presents necessary conditions for the successful morphing of the dynamic equations. The morphing process for the controller tests the idea whether the control law also satisfies the same continuum basis as the motion equations. The paper presents a framework for the class of controllers investigated for providing insight into when the controller morphing may be successful. This paper presents dimensionless quantities that render the equations of motion and controller for the inverted pendulum cart and rotary pendulum into dimensionless form. These dimensionless quantities allow comparison of controllers and systems that are not possible through simple inspection. This comparison ability is especially useful for quantifying the nonlinearities of a given system and controller compared to another system and controller having different parameter sizes, a comparison rarely seen in the control literature.
Power Management for a Fuel Cell/Battery/Supercapacitor Hybrid Locomotive
Authors: Zhao Qishen , Feng Tianheng , Chen Dongmei , Li Wei 
Published: January 2021

Abstract
Electrification of locomotive with hybridized fuel-cell, battery and supercapacitor has drawn much attention from both the academia and industry. Unlike traditional powertrain, hybrid powertrain consists of multiple power sources with a complex drivetrain structure, various efficiency performance, and different dynamics. Therefore, it is necessary to develop a power management strategy to make sure each power source operates under a quasi-optimal condition and maximize the overall powertrain efficiency. This paper presents the development of a power management framework for a novel hybrid locomotive consisting of PEM fuel cell, battery, and supercapacitor. Both the equivalent consumption management strategy (ECMS) and the stochastic dynamic programming (SDP) are applied to solve for the optimal power split strategy. The resulted power management strategy is presented in the form of policy maps, which makes it convenient for real-time in-vehicle implementations. Simulation results indicate that the SDP demonstrates advantages over the ECMS in terms of equivalent hydrogen consumption over typical locomotive driving cycles.
Developing an Applied Profile for Assessing the Perceived Effectiveness of Athletes’ Psychological Strategies: A Case Study at the Australian Institute of Sport
Authors: Doğan Umut 
Published: January 2021

Existing tools measuring athletes’ psychological strategies have various practical limitations including (a) not capturing the perceived effectiveness of psychological strategies in pursuing desirable outcomes; (b) overlooking stages of competitive involvement, such as before training or the night before competition; (c) and being predominantly paper-based. In the present case study, the author explains the process of developing an alternative assessment tool called the Profile of Psychological Strategies (ProPS). This new profile aims to measure athletes’ perceptions of which strategies they use, to pursue which desirable outcomes, and how effectively. The ProPS has its theoretical roots in Fletcher and Sarkar’s approach to developing psychological resilience and was developed based on an adapted version of Radhakrishna’s Sequence for Instrument Development. This case study can be useful both for sport experts looking for a practical and flexible way to measure athletes’ psychological strategies and for those aiming to develop their own applied assessment tool.
Microstructural properties of major white matter tracts in constant exotropia before and after strabismus surgery
Authors: Wang Yanming , Wang Xiaoxiao , Shi Hongmei , Xia Lin , Dong Jiong , Nguchu Benedictor Alexander , Uwisengeyimana Jean De Dieu , Liu Yanpeng , Zhang Du , Feng Lixia , Qiu Bensheng 
Published: January 2021

AimsThe purpose of this study was to explore the microstructural properties of the major white matter (WM) tracts in constant exotropia (XT) before and after strabismus surgery, and further investigate the association between microstructural alterations and the ocular dominance (OD).MethodsWe collected diffusion tensor imaging data of patients with XT before (n=19) and after (n=15) strabismus surgery and 20 healthy controls and evaluated OD and stereopsis. The probabilistic streamline tractography of the 24 major WM tracts was reconstructed by using the automated fibre quantification package. Fractional anisotropy and mean diffusivity (MD) along each tract were estimated, and their differences between the groups were examined. Furthermore, we evaluated the relationship between OD and the absolute value of altered microstructural parameters.ResultsWhile all postoperative XT patients restored normal stereopsis, most of their OD remained aberrant (9 out of 11). Compared with that of preoperation, the MD of postoperative patients decreased significantly along left anterior thalamic radiation (ATR), left arcuate fasciculus (AF), left corticospinal tract (CST), left cingulum cingulate (CGC) and left inferior fronto-occipital fasciculus. Moreover, OD was negatively correlated with the absolute value of MD changes in left ATR, left AF, left CST and left CGC.ConclusionMicrostructural alterations after surgery in the visuospatial network tracts may contribute to the stereopsis restoration. Additionally, the results of the correlation analysis may signify that the balanced binocular input may be more conducive for the restoration and improvement of binocular visual function, including stereopsis. Thus, restoring normal ocular balance after surgical correction may be necessary to achieve more substantial improvements.
Integrative analysis reveals early and distinct genetic and epigenetic changes in intraductal papillary and tubulopapillary cholangiocarcinogenesis
Authors: Goeppert Benjamin , Stichel Damian , Toth Reka , Fritzsche Sarah , Loeffler Moritz Anton , Schlitter Anna Melissa , Neumann Olaf , Assenov Yassen , Vogel Monika Nadja , Mehrabi Arianeb , Hoffmann Katrin , Köhler Bruno , Springfeld Christoph , Weichenhan Dieter , Plass Christoph , Esposito Irene , Schirmacher Peter , von Deimling Andreas , Roessler Stephanie 
Published: January 2021

ObjectiveA detailed understanding of the molecular alterations in different forms of cholangiocarcinogenesis is crucial for a better understanding of cholangiocarcinoma (CCA) and may pave the way to early diagnosis and better treatment options.DesignWe analysed a clinicopathologically well-characterised patient cohort (n=54) with high-grade intraductal papillary (IPNB) or tubulopapillary (ITPN) neoplastic precursor lesions of the biliary tract and correlated the results with an independent non-IPNB/ITPN associated CCA cohort (n=294). The triplet sample set of non-neoplastic biliary epithelium, precursor and invasive CCA was analysed by next generation sequencing, DNA copy number and genome-wide methylation profiling.ResultsPatients with invasive CCA arising from IPNB/ITPN had better prognosis than patients with CCA not associated with IPNB/ITPN. ITPN was localised mostly intrahepatic, whereas IPNB was mostly of extrahepatic origin. IPNB/ITPN were equally associated with small-duct and large-duct type intrahepatic CCA. IPNB exhibited mutational profiles of extrahepatic CCA, while ITPN had significantly fewer mutations. Most mutations were shared between precursor lesions and corresponding invasive CCA butROBO2mutations occurred exclusively in invasive CCA andCTNNB1mutations were mainly present in precursor lesions. In addition, IPNB and ITPN differed in their DNA methylation profiles and analyses of latent methylation components suggested that IPNB and ITPN may have different cells-of-origin.ConclusionIntegrative analysis revealed that IPNB and ITPN harbour distinct early genetic alterations, IPNB are enriched in mutations typical for extrahepatic CCA, whereas ITPN exhibited few genetic alterations and showed distinct epigenetic profiles. In conclusion, IPNB/ITPN may represent a distinctive, intermediate form of intrahepatic and extrahepatic cholangiocarcinogenesis.
Ambulatory blood pressure profile and stroke recurrence
Authors: Xu Jie , Jiang Fei , Wang Anxin , Zhi Hui , Gao Yuan , Tian Junping , Mo Jinglin , Chen Zimo , Xu An-Ding , Luo Benyan , Hu Bo , Zhang Yuqing , Zhao Xingquan , Wang Yilong , Li Hao , Shen Haipeng , Wang Yongjun 
Published: January 2021

ObjectivesTo establish a new ambulatory blood pressure (ABP) parameter (24-hour ABP profile) and evaluated its performance on stroke outcome in ischaemic stroke (IS) or transient ischaemic attack (TIA) patients.MethodsThe prospective cohort consisted of 1996 IS/TIA patients enrolled for ABP monitoring and a 3-month follow-up for stroke recurrence as outcome. Profile groups of systolic blood pressure (SBP) were identified via an advanced functional clustering method, and the associations of the profile groups and conventional ABP parameters with stroke recurrence were examined in a Cox proportional hazards model.ResultsThree discrete profile groups (n=604, 781 and 611 in profiles 1, 2 and 3, respectively) in 24-hour ambulatory SBP were identified. Profile 1 resembled most to the normal diurnal blood pressure pattern; profile 2 also dropped at night, but climbed earlier and with higher morning surge; while profile 3 had sustained higher nocturnal SBP without significant nocturnal SBP decline. The incidence of stroke recurrence was 2.9%, 3.9% and 5.5% in profiles 1, 2 and 3, respectively. After adjustment for covariates, profile 3 was significantly associated with higher risk of stroke recurrence with profile 1 as reference (HR 1.76, 95% CI: 1.00 to 3.09), while no significant difference was observed between profiles 2 and 1 (HR 1.22, 95% CI: 0.66 to 2.25). None of conventional ABP parameters showed significant associations with the outcome.ConclusionsAmbulatory 24-hour SBP profile is associated with short-term stroke recurrence. Profiles of ABP may help improve identification of stroke recurrence by capturing the additive effects of individual ABP parameters.
Fermion and photon gap-equations in Minkowski space within the Nakanishi integral representation method
Authors: Mezrag Cédric , Salmè Giovanni 
Published: January 2021

AbstractThe approach based on the Nakanishi integral representation of n-leg transition amplitudes is extended to the treatment of the self-energies of a fermion and an (IR-regulated) vector boson, in order to pave the way for constructing a comprehensive application of the technique to both gap- and Bethe-Salpeter equations, in Minkowski space. The achieved result, namely a 6-channel coupled system of integral equations, eventually allows one to determine the three Källén–Lehman weights for fully dressing the propagators of fermion and photon. A first consistency check is also provided. The presented formal elaboration points to embed the characteristics of the non-perturbative regime at a more fundamental level. It yields a viable tool in Minkowski space for the phenomenological investigation of strongly interacting theories, within a QFT framework where the dynamical ingredients are made transparent and under control.