bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hierarchical Multi-Timescale Energy Management for Hybrid-Electric Aircraft
Authors: Wang Wenqing , Koeln Justin P. 
Published: January 2021

Abstract
Hybrid-electric aircraft represent an important step in the transition from conventional fuel-based propulsion to fully-electric aircraft. For hybrid power systems, overall aircraft performance and efficiency highly depend on the coordination of the fuel and electrical systems and the ability to effectively control state and input trajectories at the limits of safe operation. In such a safety-critical application, the chosen control strategy must ensure the closed-loop system adheres to these operational limits. While hierarchical Model Predictive Control (MPC) has proven to be a computationally efficient approach to coordinated control of complex systems across multiple timescales, most formulations are not supported by theoretical guarantees of actuator and state constraint satisfaction. To provide guaranteed constraint satisfaction, this paper presents set-based hierarchical MPC of a 16 state hybrid-electric aircraft power system. Within the proposed two-level vertical hierarchy, the long-term control decisions of the upper-level controller and the short-term control decisions of the lower-level controller are coordinated through the use of waysets. Simulation results show the benefits of this coordination in the context of hybrid-electric aircraft performance and demonstrate the practicality of applying set-based hierarchical MPC to complex multi-timescale systems.
Iterative Learning Control for Hybrid Systems
Authors: Mishra Kirti D. , Srinivasan K. 
Published: January 2021

Abstract
Iterative learning control (ILC) has been growing in applicability, along with growth in theory for classes of linear and nonlinear systems, and this study extends the theory of ILC to hybrid systems. A lifted form representation of hybrid systems with input-output dependent switching rules is developed, and the proposed lifted form representation is modeled as a switched system with arbitrary/unconstrained switching rules in the trial domain for control design. The causality of hybrid systems in the time domain results in the (lower) triangular structure of switched systems in the trial domain, the triangular structure enabling systematic and efficient control design. A unique aspect of the control design method developed for ILC of hybrid systems in this study is that a solution to the required set of linear matrix inequalities (LMIs) is guaranteed to exist under mild assumptions, which is in contrast to many other studies proposing LMI based solutions in controls literature. The proposed method is validated numerically for a motion control application, and robust and monotonic convergence of the tracking error to zero is demonstrated.
Design and Analysis of a New Mechanism for a Snake Like Robot
Authors: Garcia Johnathon , Lee Kooktae 
Published: January 2021

Abstract
In this paper, a novel snake like robot design is presented and analyzed. The structure described desires to obtain a robot that is most like a snake found in nature. This is achieved with the combination of both rigid and soft link structures by implementing a 3D printed rigid link and a soft cast silicone skin. The proposed structure serves to have a few mechanical improvements while maintaining the positives of previous designs. The implementation of the silicone skin presents the opportunity to use synthetic scales and directional friction. The design modifications of this novel design are analyzed on the fronts of the kinematics and minimizing power loss. Minimization of power loss is done through a numerical minimization of three separate parameters with the smallest positive power loss being used. This results in the minimal power loss per unit distance. This research found that the novel structure presented can be effectively described and modeled, such that they could be applied to a constructed model.
Estimation of Parameter Probability Distributions for Lithium-Ion Battery String Models Using Bayesian Methods
Authors: Couto Luis D. , Zhang Dong , Aitio Antti , Moura Scott , Howey David 
Published: January 2021

Abstract
This paper addresses the parameter estimation problem for lithium-ion battery pack models comprising cells in series. This valuable information can be exploited in fault diagnostics to estimate the number of cells that are exhibiting abnormal behaviour, e.g. large resistances or small capacities. In particular, we use a Bayesian approach to estimate the parameters of a two-cell arrangement modelled using equivalent circuits. Although our modeling framework has been extensively reported in the literature, its structural identifiability properties have not been reported yet to the best of the authors’ knowledge. Moreover, most contributions in the literature tackle the estimation problem through point-wise estimates assuming Gaussian noise using e.g. least-squares methods (maximum likelihood estimation) or Kalman filters (maximum a posteriori estimation). In contrast, we apply methods that are suitable for nonlinear and non-Gaussian estimation problems and estimate the full posterior probability distribution of the parameters. We study how the model structure, available measurements and prior knowledge of the model parameters impact the underlying posterior probability distribution that is recovered for the parameters. For two cells in series, a bimodal distribution is obtained whose modes are centered around the real values of the parameters for each cell. Therefore, bounds on the model parameters for a battery pack can be derived.
Sampled-Data Observer Based Dynamic Surface Control of Delayed Neuromuscular Functional Electrical Stimulation
Authors: Zhang Qiang , Iyer Ashwin , Sun Ziyue , Dodson Albert , Sharma Nitin 
Published: January 2021

Abstract
Functional electrical stimulation (FES) is a potential technique for reanimating paralyzed muscles post neurological injury/disease. Several technical challenges including difficulty in measuring and compensating for delayed muscle activation levels inhibit its satisfactory control performance. In this paper, an ultrasound (US) imaging approach is proposed to measure delayed muscle activation levels under the implementation of FES. Due to low sampling rates of US imaging, a sampled-data observer (SDO) is designed to estimate the muscle activation in a continuous manner. The SDO is combined with continuous-time dynamic surface control (DSC) approach that compensates for the electromechanical delay (EMD) in the tibialis anterior (TA) activation dynamics. The stability analysis based on the Lyapunov-Krasovskii function proves that the SDO-based DSC plus delay compensation (SDO-DSC-DC) approach achieves semi-global uniformly ultimately bounded (SGUUB) tracking performance. Simulation results on an ankle dorsiflexion neuromusculoskeletal system show the root mean square error (RMSE) of desired trajectory tracking is reduced by 19.77 % by using the proposed SDO-DSC-DC compared to the DSC-DC without the SDO. The findings provide potentials for rehabilitative devices, like powered exoskeleton and FES, to assist or enhance human limb movement based on the corresponding muscle activities in real-time.
Achieving Improved Personalization and Energy Efficiency in Cohabited Work-Spaces Through Data-Driven Predictive Control
Authors: Naqvi Syed Ahsan Raza , Nawrocki Zachary , Bin Tariq Zaid , Kar Koushik , Mishra Sandipan 
Published: January 2021

Abstract
This paper studies the problem of indoor zone temperature control in shared work-spaces equipped with heterogeneous heating and cooling sources with the goal of increased energy savings and environment personalization. We consider two scenarios to assess the performance of our control strategies. The first scenario requires time-bound pre-cooling/pre-heating of a shared space in preparation for a scheduled activity (Scenario A). The second scenario considers a cohabited work-space where occupants have different temperature preferences (Scenario B). Utilizing an on-campus smart conference room (SCR) as a test-bed, we use data-driven model learning to establish a relationship between the room’s heating, ventilation and cooling (HVAC) operations and the zone temperatures. Next, we use a model predictive control (MPC)-based approach to achieve a desired average temperature while minimizing power consumption (for Scenario A) and minimize the thermal discomfort experienced by individuals based on their temperature preferences (for Scenario B). The experimental results show that for Scenario A, the proposed control policy can save a significant amount of energy and achieve the desired mean temperature in the space fairly accurately. We further note that for Scenario B, the control scheme can achieve a significant spatial differentiation in temperature towards satisfying the occupants’ thermal preferences.
Graph-Based Design and Control Optimization of a Hybrid Electrical Energy Storage System
Authors: Laird Cary , Docimo Donald , Aksland Christopher T. , Alleyne Andrew G. 
Published: January 2021

Abstract
Hybrid energy storage systems are a popular alternative to traditional electrical energy storage mechanisms for electric vehicles. Consisting of multiple heterogeneous storage elements, these systems require thoughtful design and control techniques to ensure adequate electrical performance and minimal added weight. In this work, a graph-based design optimization framework is extended to facilitate design and control optimization of a battery-ultracapacitor hybrid energy storage system. For a given high ramp rate load profile, a hybrid electrical energy storage system consisting of battery and ultracapacitor packs with proportional-integral controllers is considered. A multi-objective optimization problem is formulated to simultaneously optimize sizing and performance of the system by minimizing mass and deviations from ideal controller performance. This optimization is achieved by adjusting the size of the energy storage system and parameters of the feedback controller. A Pareto curve is provided, which exhibits the tradeoffs between sizing and performance of the hybrid energy storage system. Dynamic simulation results demonstrate optimized designs outperform initial designs in both sizing and electrical performance objectives. The design and control optimization approach is shown to outperform a similar sizing optimization approach.
Safe Decision and Control of Connected Automated Vehicles for an Unprotected Left Turn
Authors: Oh Sanghoon , Zhang Linjun , Tseng Eric , Williams Wayne , Kourous Helen , Orosz Gabor 
Published: January 2021

Abstract
The unprotected left turn of a connected automated vehicle (CAV) is investigated when it has a potential conflict with a connected human-driven vehicle (CHV) approaching in the opposite lane. A control architecture is proposed that includes interactions between the decision making, motion planning, and control levels. By utilizing the road context and information received via vehicle-to-everything (V2X) communication, a reduced state space representation is determined which allows the CAV to evaluate safety in a fast and efficient manner Using a temporal metric, a safety evaluation algorithm is developed which determines the safety of the decision making at controller level. To evaluate the algorithms, data collected with real vehicles is utilized.
Numerical Simulation of Vortex-Induced Vibration of Two Tandem Cylinders With Different Diameters Under Uniform Flow
Authors: Fu Xuepeng , Xu Yuwang , Zhang Mengmeng , Ren Haojie , Zhao Bing , Fu Shixiao 
Published: January 2021

Abstract
Vortex-induced vibrations (VIV) of two elastically mounted circular cylinders with different diameters in tandem arrangement are investigated in a two-dimensional (2D) numerical simulation. The fluid domain is simulated by solving 2D Reynold-Averaged Navier-Stokes equations. Meanwhile, the VIV response of the structures is obtained by solving the motion equation using the 4th Runge-Kutta method. The parameters of the cylinders are designed according to an experimental study of flexible risers. Simulation of an elastically mounted single cylinder is firstly carried out and compared with published experimental results to verify the method utilized in the paper. The results of single cylinder show the response frequencies of the bluff cylinders and the flexible cylinder are comparable. In the simulation of the tandem cylinders, a “frequency capture” phenomenon that the oscillation frequencies of downstream cylinder are locked on to that of the up-stream one although they are with different diameters is observed. It also occurs in the experimental study of flexible cylinders. The mechanism behind is analyzed in the paper.
Episodic exhumation of the Appalachian orogen in the Catskill Mountains (New York State, USA)
Authors: Shorten Chilisa M. , Fitzgerald Paul G. 
Published: January 2021

Abstract
Increasing evidence indicates the eastern North American passive margin has not remained tectonically quiescent since Jurassic continental breakup. The identification, timing, resolution, and significance of post-orogenic exhumation, notably an enigmatic Miocene event, are debated. We add insight by constraining the episodic cooling and exhumation history of the Catskill Mountains (New York, USA) utilizing apatite fission-track thermochronology and apatite (U-Th)/He data from a ∼1 km vertical profile. Multi-kinetic inverse thermal modeling constrains three phases of cooling: Early Jurassic to Early Cretaceous (1–3 °C/m.y.), Early Cretaceous to early Miocene (∼0.5 °C/m.y.), and since Miocene times (1–2 °C/m.y.). Previous thermochronologic studies were unable to verify late-stage cooling and/or exhumation (typically post-Miocene and younger) because late-stage cooling was commonly a spurious artifact of earlier mono-kinetic annealing algorithms. Episodic cooling phases are correlative with rifting, passive-margin development, and drainage reorganization causing landscape rejuvenation. Geomorphologic documentation of increased offshore mid-Atlantic sedimentation rates and onshore erosion support the documented accelerated Miocene cooling and exhumation.
A new model for the growth of normal faults developed above pre-existing structures
Authors: Bramham Emma K. , Wright Tim J. , Paton Douglas A. , Hodgson David M. 
Published: January 2021

AbstractConstraining the mechanisms of normal fault growth is essential for understanding extensional tectonics. Fault growth kinematics remain debated, mainly because the very earliest phase of deformation through recent syn-kinematic deposits is rarely documented. To understand how underlying structures influence surface faulting, we examined fault growth in a 10 ka magmatically resurfaced region of the Krafla fissure swarm, Iceland. We used a high-resolution (0.5 m) digital elevation model derived from airborne lidar to measure 775 fault profiles with lengths ranging from 0.015 to 2 km. For each fault, we measured the ratio of maximum vertical displacement to length (Dmax/L) and any nondisplaced portions of the fault. We observe that many shorter faults (&lt;200 m) retain fissure-like features, with no vertical displacement for substantial parts of their displacement profiles. Typically, longer faults (&gt;200 m) are vertically displaced along most of their surface length and have Dmax/L at the upper end of the global population for comparable lengths. We hypothesize that faults initiate at the surface as fissure-like fractures in resurfaced material as a result of flexural stresses caused by displacements on underlying faults. Faults then accrue vertical displacement following a constant-length model, and grow by dip and strike linkage or lengthening when they reach a bell-shaped displacement-length profile. This hybrid growth mechanism is repeated with deposition of each subsequent syn-kinematic layer, resulting in a remarkably wide distribution of Dmax/L. Our results capture a specific early period in the fault slip-deposition cycle in a volcanic setting that may be applicable to fault growth in sedimentary basins.
Association of ambient air pollution with age-related macular degeneration and retinal thickness in UK Biobank
Authors: Chua Sharon Y L , Warwick Alasdair , Peto Tunde , Balaskas Konstantinos , Moore Anthony T , Reisman Charles , Desai Parul , Lotery Andrew J , Dhillon Baljean , Khaw Peng T , Owen Christopher G , Khawaja Anthony P , Foster Paul J , Patel Praveen J 
Published: January 2021

AimTo examine the associations of air pollution with both self-reported age-related macular degeneration (AMD), and in vivo measures of retinal sublayer thicknesses.MethodsWe included 115 954 UK Biobank participants aged 40–69 years old in this cross-sectional study. Ambient air pollution measures included particulate matter, nitrogen dioxide (NO2) and nitrogen oxides (NOx). Participants with self-reported ocular conditions, high refractive error (< −6 or > +6 diopters) and poor spectral-domain optical coherence tomography (SD-OCT) image were excluded. Self-reported AMD was used to identify overt disease. SD-OCT imaging derived photoreceptor sublayer thickness and retinal pigment epithelium (RPE) layer thickness were used as structural biomarkers of AMD for 52 602 participants. We examined the associations of ambient air pollution with self-reported AMD and both photoreceptor sublayers and RPE layer thicknesses.ResultsAfter adjusting for covariates, people who were exposed to higher fine ambient particulate matter with an aerodynamic diameter <2.5 µm (PM2.5, per IQR increase) had higher odds of self-reported AMD (OR=1.08, p=0.036), thinner photoreceptor synaptic region (β=−0.16 µm, p=2.0 × 10−5), thicker photoreceptor inner segment layer (β=0.04 µm, p=0.001) and thinner RPE (β=−0.13 µm, p=0.002). Higher levels of PM2.5 absorbance and NO2 were associated with thicker photoreceptor inner and outer segment layers, and a thinner RPE layer. Higher levels of PM10 (PM with an aerodynamic diameter <10 µm) was associated with thicker photoreceptor outer segment and thinner RPE, while higher exposure to NOx was associated with thinner photoreceptor synaptic region.ConclusionGreater exposure to PM2.5 was associated with self-reported AMD, while PM2.5, PM2.5 absorbance, PM10, NO2 and NOx were all associated with differences in retinal layer thickness.
Lifestyle factors associated with incidence of rheumatoid arthritis in US adults: analysis of National Health and Nutrition Examination Survey database and meta-analysis
Authors: Ye Ding , Mao Yingying , Xu Yang , Xu Xueli , Xie Zhijun , Wen Chengping 
Published: January 2021

ObjectiveTo quantify rheumatoid arthritis (RA) cases attributable to selected non-genetic risk factors.DesignNational Health and Nutrition Examination Survey (NHANES) and meta-analysis.ParticipantsUS adults.Data sourcesThe prevalence of exposure was obtained from NHANES. Weighted analysis was performed to account for the complex sampling design in NHANES. PubMed and Web of Science up to 31 March 2019 were searched to identify epidemiological studies reported the association between non-genetic risk factors and RA in US adults. Relative risk (RR) value and the corresponding CI were pooled by meta-analysis to evaluate the associations between modifiable risk factors and RA. Population attributable fraction (PAF) was calculated based on the prevalence and RR data.ResultsThe weighted percentages of former smokers, current smokers and overweight or obese people were 24.84%, 23.93% and 63.97%, and the average alcohol consumption was 51.34 g/week. In the meta-analysis, we found that former smokers (RR 1.22, 95% CI 1.10 to 1.36) and current smokers (RR 1.47, 95% CI 1.29 to 1.68) had higher risks of RA. Overweight and obese individuals had 1.27-fold (95% CI 1.09 to 1.48) increased risk of RA. Each per 50 g/week increment of alcohol consumption was associated with 8% (95% CI 0% to 16%) reduction in the risk of RA. Therefore, PAF value of smoking was 14.00% (95% CI 8.13% to 23.33%). Excess body mass index (BMI) was found to account for 14.73% (95% CI 5.45% to 23.50%) of RA incidence. The fraction of RA risk attributed by low alcohol intake was 8.21% (95% CI 0.31% to 16.39%). Collectively, we found that 32.69% (95% CI 13.41% to 50.96%) of RA cases were attributable to smoking, overweight or obesity and low alcohol drinking.ConclusionNearly 33% of RA incidence was attributed to smoking, excess BMI and low alcohol drinking in USA. Our findings could provide a basis for developing guidelines of RA prevention and control in USA.
Turning the tide: a quasi-experimental study on a coaching intervention to reduce burn-out symptoms and foster personal resources among medical residents and specialists in the Netherlands
Authors: Solms Lara , van Vianen Annelies , Koen Jessie , Theeboom Tim , de Pagter Anne P J , De Hoog Matthijs 
Published: January 2021

ObjectivesPhysician burn-out is increasing, starting already among residents. The consequences of burn-out are not limited to physicians’ well-being, they also pose a threat to patient care and safety. This study investigated the effectiveness of a professional coaching intervention to reduce burn-out symptoms and foster personal resources in residents and specialists.DesignIn a controlled field experiment, medical residents and specialists received six coaching sessions, while a control group did not undergo any treatment. The authors assessed burn-out symptoms of exhaustion and cynicism, the personal resources psychological capital, psychological flexibility and self-compassion, as well as job demands and job resources with validated questionnaires (January 2017 until August 2018). The authors conducted repeated measures analyses of variance procedures to examine changes over time for the intervention and the control group.SettingFour academic hospitals in the Netherlands.ParticipantsA final sample of 57 residents and specialists volunteered in an individual coaching programme. A control group of 57 physicians did not undergo any treatment.InterventionCoaching was provided by professional coaches during a period of approximately 10 months aiming at personal development and growth.ResultsThe coaching group (response rate 68%, 57 physicians, 47 women) reported a reduction in burn-out symptoms and an increase in personal resources after the coaching intervention, while no such changes occurred in the control group (response rate 35%, 42 women), as indicated by significant time × group interactions, all p<0.01. Specifically, physicians increased their psychological capital (ηp2=0.139), their self-compassion (ηp2=0.083), and reported significantly less exhaustion (ηp2=0.126), the main component of the burn-out syndrome.ConclusionThis study suggests that individual coaching is a promising route to reduce burn-out symptoms in both residents and specialists. Moreover, it strengthens personal resources that play a crucial role in the prevention of burn-out.