bluuebunny/crossref_metadata_2025 huggingface dataset:
Aquinas, Contemplation, and Theology
Authors: Bauerschmidt Frederick Christian
Published: January 2021

Jonathan Lear's account of Aristotle and the human person as a systematic understander can shed light on how Thomas Aquinas sees the passage from contemplation of worldly things to the contemplation of the divine essence. In grasping the essences of mundane particulars, the systematic understander ‘spiritualizes’ them, and simultaneously comes to grasp both self and God. This account of contemplation can further help illuminate Aquinas's understanding of the nature of the theological task as an exercise of systematic understanding of the particulars from which the scriptural narrative of signs and examples is constructed. Finally, the theologian's own path as a systematic understander is retraced for his or her students in sharing the fruits of contemplation through teaching.
Tight junction proteins in the small intestine and prefrontal cortex of female rats exposed to stress of chronic isolation starting early in life
Authors: Karailiev Peter , Hlavacova Natasa , Chmelova Magdalena , Homer Natalie Z. M. , Jezova Daniela
Published: January 2021

Background

Simultaneous evaluation of barrier protein expression in the gut and the brain and their modulation under stress conditions have not been studied before now. As the permeability and function of the gut and blood‐brain barrier are different and both express the MRs, we hypothesized that stress of post‐weaning social isolation induces changes in tight junction protein expression in the gut which are (1) independent of changes in the brain and (2) are mediated via the mineralocorticoid receptor (MR).

Methods

First, using UPLC‐MS/MS we have successfully validated and selected a dose (1.2 mg/rat/day) of the MR antagonist spironolactone to treat female rats exposed to stress of chronic isolation or control conditions from postnatal day 21 for 9 weeks.

Key Results

Isolation stress caused an enhancement of gene expression of occludin and ZO‐1 and a decrease in claudin‐5 and MR expression in both the small intestine and prefrontal cortex. Isolation stress failed to decrease claudin‐5 (small intestine) and MR (prefrontal cortex) gene expression in spironolactone‐treated rats. MR blockade resulted in a decrease in claudin‐15 expression in the small intestine. Anxiogenic effect of chronic stress, measured in elevated plus‐maze test, was partly prevented by spironolactone treatment.

Conclusions & Inferences

Claudins, the main regulators of intestinal barrier permeability responded to chronic stress of social isolation and/or simultaneous blockade of MR in female rats by alterations independent of changes in the brain cortex. The results suggest a physiological role of MR in the control of claudin expression in the small intestine, but not in the brain cortex.
The impact of multifactorial stress combination on plant growth and survival
Authors: Zandalinas Sara I. , Sengupta Soham , Fritschi Felix B. , Azad Rajeev K. , Nechushtai Rachel , Mittler Ron
Published: January 2021

Climate change‐driven extreme weather events, combined with increasing temperatures, harsh soil conditions, low water availability and quality, and the introduction of many man‐made pollutants, pose a unique challenge to plants. Although our knowledge of the response of plants to each of these individual conditions is vast, we know very little about how a combination of many of these factors, occurring simultaneously, that is multifactorial stress combination, impacts plants.

Seedlings of wild‐type and different mutants of Arabidopsis thaliana plants were subjected to a multifactorial stress combination of six different stresses, each applied at a low level, and their survival, physiological and molecular responses determined.

Our findings reveal that, while each of the different stresses, applied individually, had a negligible effect on plant growth and survival, the accumulated impact of multifactorial stress combination on plants was detrimental. We further show that the response of plants to multifactorial stress combination is unique and that specific pathways and processes play a critical role in the acclimation of plants to multifactorial stress combination.

Taken together our findings reveal that further polluting our environment could result in higher complexities of multifactorial stress combinations that in turn could drive a critical decline in plant growth and survival.
Drought by CO2interactions in trees: a test of the water savings mechanism
Authors: Jiang Mingkai , Kelly Jeff W.G. , Atwell Brian J. , Tissue David T. , Medlyn Belinda E.
Published: January 2021

Elevated atmospheric CO2(eCa) may benefit plants during drought by reducing stomatal conductance (gs) but any ‘water savings effect’ could be neutralized by concurrent stimulation of leaf area. We investigated whether eCaenhanced water savings, thereby ameliorating the impact of drought on carbon and water relations in trees.

We report leaf‐level gas exchange and whole‐plant and soil water relations during a short‐term dry‐down in twoEucalyptusspecies with contrasting drought tolerance. Plants had previously been established for 9 to 11 months in steady‐state conditions of ambient atmospheric CO2(aCa) and eCa, with half of each treatment group exposed to sustained drought for 5 to 7 months.

The lower stomatal conductance under eCadid not lead to soil moisture savings during the dry‐down due to the counteractive effect of increased whole‐plant leaf area. Nonetheless, eCa‐grown plants maintained higher photosynthetic rates and leaf water potentials, making them less stressed during the dry‐down, despite being larger. These effects were more pronounced in the xeric species than the mesic species, and in previously water‐stressed plants.

Our findings indicate that eCamay enhance plant performance during drought despite a lack of soil water savings, especially in species with more conservative growth and water‐use strategies.
Neonatal Fc receptor induces intravenous immunoglobulin growth suppression in Langerhans cell histiocytosis
Authors: Nabeshima Yuka , Kataoka Tatsuki R. , Ueshima Chiyuki , Saito Narumi , Hirata Masahiro , Takeuchi Yasuhide , Takei Yusuke , Moriyoshi Koki , Ono Kazuo , Haga Hironori
Published: January 2021

The neonatal Fc receptor (FcRn) plays a role in trafficking IgG and albumin and is thought to mediate intravenous immunoglobulin (IVIG) therapy for certain diseases. IVIG can be used for the treatment of human Langerhans cell histiocytosis (LCH); however, the mechanism remains unclear. The expression and function of FcRn protein have not been studied in LCH, though the expression of FcRn messenger RNA (mRNA) have been reported. In this report, we confirmed the expression of FcRn in 26 of 30 pathological cases (86.7%) diagnosed immunohistochemically as LCH. The expression was independent of age, gender, location, multi‐ or single‐system, and the status of BRAFV600E immunostaining. We also confirmed the expression of FcRn mRNA and protein in the human LCH‐like cell line, ELD‐1. FcRn suppressed albumin consumption and growth of IVIG preparation‐treated ELD‐1 cells, but not of IVIG preparation‐untreated or FcRn‐knockdown ELD‐1 cells. In addition, FITC‐conjugated albumin was taken into Rab11‐positive recycle vesicles in mock ELD‐1 cells but not in FcRn‐knockdown ELD‐1 cells. IVIG preparation prolonged this status in mock ELD‐1 cells. Therefore, ELD‐1 recycled albumin via FcRn and albumin was not used for metabolism. Our results increase our understanding of the molecular mechanism of IVIG treatment of LCH.
Patient characteristics associated with SARS‐CoV‐2 infection in parturients admitted for labour and delivery in Massachusetts during the spring 2020 surge: A prospective cohort study
Authors: Reale Sharon C. , Lumbreras‐Marquez Mario I. , King Chih H. , Burns Stacey L. , Fields Kara G. , Diouf Khady , Goldfarb Ilona T. , Ciaranello Andrea L. , Robinson Julian N. , Gregory Katherine E. , Huybrechts Krista F. , Bateman Brian T.
Published: January 2021

Background

While studies from large cities affected by coronavirus disease 2019 (COVID‐19) have reported on the prevalence of SARS‐CoV‐2 in the context of universal testing during admission for delivery, the patient demographic, social and clinical factors associated with SARS‐CoV‐2 infection in pregnant women are not fully understood.

Objective

To evaluate the epidemiological factors associated with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection in women admitted for labour and delivery, in the context of universal screening at four Boston‐area hospitals.

Methods

In this prospective cohort study, we reviewed the health records of all women admitted for labour and delivery at four hospitals from the largest health system in Massachusetts between 19 April 2020 and 27 June 2020. We calculated the risk of SARS‐CoV‐2 infection, including asymptomatic infection. We calculated associations between SARS‐CoV‐2 infection and demographic and clinical characteristics.

Results

A total of 93 patients (3.2%, 95% confidence interval 2.5, 3.8) tested positive for SARS‐CoV‐2 infection on admission for labour and delivery out of 2945 patients included in the analysis; 80 (86.0%) of the patients who tested positive were asymptomatic at the time of testing. Factors associated with SARS‐CoV‐2 infection included the following: younger age, obesity, African American or Hispanic race/ethnicity, residence in heavily affected communities (as measured in cases reported per capita), presence of a household member with known SARS‐CoV‐2 infection, non‐health care essential worker occupation and MassHealth or Medicaid insurance compared to commercial insurance. 93.8% of patients testing positive for SARS‐CoV‐2 on admission had one or more identifiable factors associated with disease acquisition.

Conclusions

In this large sample of deliveries during the height of the surge in infections during the spring of 2020, SARS‐CoV‐2 infection was largely concentrated in patients with distinct demographic characteristics, those largely from disadvantaged communities. Racial disparities seen in pregnancy persist with respect to SARS‐CoV‐2 infection.
Psychological power alters cognitive efficiency
Authors: Lin Enru , Freydefont Laure , Schmid Petra C.
Published: January 2021

Power is known to promote cognitive processing in a goal‐directed way. However, it is unknown whether powerful individuals invest more resources when pursuing their goals or whether they invest their resources more efficiently. We examined how experiencing high versus low power affects the efficient investment of cognitive resources using electroencephalography (EEG). Specifically, event‐related desynchronization (ERD) in the upper alpha band (10.5–12.75 Hz) was used to quantify the use of cognitive resources during task completion. Results showed that high‐power participants used fewer neural resources compared to low‐power participants across the whole brain but task performance did not differ between groups. These findings demonstrate that, instead of investing more resources, high‐power participants performed the task with greater cognitive efficiency compared to low‐power participants. Performing tasks efficiently could help powerholders deal with their demanding jobs and responsibilities.
Next generation science classrooms: The development of a questionnaire for examining student experiences in science classrooms
Authors: Campbell Todd , Lee Hyunju , Longhurst Max , McKenna Thomas J. , Coster Daniel , Lundgren Lisa
Published: January 2021

In the United States and internationally, there has been an increased emphasis on the practice turn or a focus on engaging students in more authentic representations of how science is practiced. In this article, we describe the development of a student questionnaire to investigate the extent to which students report being engaged in learning experiences similar to those explicated through the practice turn. We developed a questionnaire that consisted of 35 questions that were separated into four constructs. The questionnaire was determined to be internally consistent, with a high reliability estimate. Confirmatory factor analysis showed item clustering consistent with the research‐derived constructs indicative of a practice turn focus in science classrooms. Furthermore, early evidence from this pilot study is provided to reveal the ability of the questionnaire to detect student experiences that are differentiated at the teacher‐level. Based on the analyses completed, the questionnaire appears to be a needed and useful measure of student‐reported learning experiences that can provide an indication of students’ opportunity to learn in ways aligned to the most recent reforms in science education.
Ethylene increases the cold tolerance of apple via the MdERF1B–MdCIbHLH1 regulatory module
Authors: Wang Yicheng , Jiang Huiyan , Mao Zuolin , Liu Wenjun , Jiang Shenghui , Xu Haifeng , Su Mengyu , Zhang Jing , Wang Nan , Zhang Zongying , Chen Xuesen
Published: January 2021

Cold stress has always been a major abiotic factor affecting the yield and quality of temperate fruit crops. Ethylene plays a critical regulatory role in the cold stress response, but the underlying molecular mechanisms remain elusive. Here, we revealed that ethylene positively modulates apple responses to cold stress. Treatment with 1‐aminocyclopropane‐1‐carboxylate (an ethylene precursor) and aminoethoxyvinylglycine (an ethylene biosynthesis inhibitor) respectively increased and decreased the cold tolerance of apple seedlings. Consistent with the positive effects of ethylene on cold stress responses, a low‐temperature treatment rapidly induced ethylene release and the expression of MdERF1B, which encodes an ethylene signaling activator, in apple seedlings. Overexpression of MdERF1B significantly increased the cold tolerance of apple plant materials (seedlings and calli) and Arabidopsis thaliana seedlings. A quantitative real‐time PCR analysis indicated that MdERF1B upregulates the expression of the cold‐responsive gene MdCBF1 in apple seedlings. Moreover, MdCIbHLH1, which functions upstream of CBF‐dependent pathways, enhanced the binding of MdERF1B to target gene promoters as well as the consequent transcriptional activation. The stability of MdERF1B–MdCIbHLH1 was affected by cold stress and ethylene. Furthermore, MdERF1B interacted with the promoters of two genes critical for ethylene biosynthesis, MdACO1 and MdERF3. The resulting upregulated expression of these genes promoted ethylene production. However, the downregulated MdCIbHLH1 expression in MdERF1B‐overexpressing apple calli significantly inhibited ethylene production. These findings imply that MdERF1B–MdCIbHLH1 is a potential regulatory module that integrates the cold and ethylene signaling pathways in apple.
DGEN Aeropropulsion Research Turbofan Core/Combustor-Noise Measurements—Experiment and Modal Structure at Core-Nozzle Exit1
Authors: Boyle Devin K. , Henderson Brenda S. , Hultgren Lennart S.
Published: January 2021

Data from a recent core/combustor-noise source-diagnostic test (SDT) utilizing a small turbofan engine are analyzed. The campaign continued the exploration begun in a baseline test, but with more extensive acoustic instrumentation. Both tests were aimed at developing a better understanding of propulsion-noise sources and their impact on the farfield noise signature, in order to enable improved turbofan noise-prediction methods and noise-mitigation techniques. Simultaneous high-data-rate acoustic measurements (93 channels in total) were obtained using a circumferential sensor array at the core-nozzle exit in conjunction with sideline and farfield microphone arrays for several relevant engine operational points. Measurements were repeated for different circumferential and sideline array configurations, as well as for redundancy. The unsteady pressure field at the core-nozzle exit is documented in detail. Previous work suggested that the ±1 azimuthal duct mode could be cut on at this location, which would have implications for combustor-noise modeling and prediction. The modal decomposition of the combustor noise at the core-nozzle exit verifies this observation. Select farfield sound pressure level (SPL) spectra are also presented.
Animal Orientation Affects Brain Biomechanical Responses to Blast-Wave Exposure
Authors: Unnikrishnan Ginu , Mao Haojie , Sajja Venkata Siva Sai Sujith , van Albert Stephen , Sundaramurthy Aravind , Rubio Jose E. , Subramaniam Dhananjay Radhakrishnan , Long Joseph , Reifman Jaques
Published: January 2021

In this study, we investigated how animal orientation within a shock tube influences the biomechanical responses of the brain and cerebral vasculature of a rat when exposed to a blast wave. Using three-dimensional finite element (FE) models, we computed the biomechanical responses when the rat was exposed to the same blast-wave overpressure (100 kPa) in a prone (P), vertical (V), or head-only (HO) orientation. We validated our model by comparing the model-predicted and the experimentally measured brain pressures at the lateral ventricle. For all three orientations, the maximum difference between the predicted and measured pressures was 11%. Animal orientation markedly influenced the predicted peak pressure at the anterior position along the midsagittal plane of the brain (P = 187 kPa; V = 119 kPa; and HO = 142 kPa). However, the relative differences in the predicted peak pressure between the orientations decreased at the medial (21%) and posterior (7%) positions. In contrast to the pressure, the peak strain in the prone orientation relative to the other orientations at the anterior, medial, and posterior positions was 40–88% lower. Similarly, at these positions, the cerebral vasculature strain in the prone orientation was lower than the strain in the other orientations. These results show that animal orientation in a shock tube influences the biomechanical responses of the brain and the cerebral vasculature of the rat, strongly suggesting that a direct comparison of changes in brain tissue observed from animals exposed at different orientations can lead to incorrect conclusions.
Complex Energy Networks Optimization: Part I—Development and Validation of a Software for Optimal Load Allocation
Authors: Ancona Maria Alessandra , Bianchi Michele , Branchini Lisa , De Pascale Andrea , Melino Francesco , Peretto Antonio , Rosati Jessica
Published: January 2021

The growing diffusion of the distributed generation systems, due to the European and national legislations which impose the fossil fuel and greenhouse gas emissions reduction and the renewable sources exploitation, have led to an increase in the complexity of the existing energy networks. The main issue of the complex energy grids is their management, which consists in the resolution and optimization of the load allocation problem by minimizing the primary energy consumption and, thus, improving the overall efficiency. In this context, the aim of this paper is to develop and validate a nonlinear algorithm suitable for the resolution of the load allocation problem. In detail, the software combo, which has been developed by the University of Bologna, is based on a nonheuristic algorithm and allows to optimize a complex energy network—characterized by electrical, thermal, cooling and fuel fluxes—by evaluating all the possible combinations of solutions. The objective function of the software consists in the minimization of the total cost of energy production, including not only the variable costs, but also the costs related to the environmental impact of the energy systems. In this paper the mathematical model of the algorithm at the basis of the software combo is presented and described in detail. Furthermore, the software has been validated by its application to a case study and comparing the results with the ones obtained with a previously developed software based on a genetic algorithm (heuristic nonlinear method).
Redesign of Axial Fan Using Viscous Inverse Design Method Based on Boundary Vorticity Flux Diagnosis
Authors: Liu Hui , Jiang Boyan , Wang Wei , Yang XiaoPei , Wang Jun
Published: January 2021

The inverse design method for turbomachinery can directly acquire a blade geometry with specific aerodynamic parameters, such as pressure loading on the blade surfaces. The difference between the inverse design and direct analysis design is that the management of the flow field is controlled by aerodynamic parameters instead of geometric parameters. Although the inverse design has been studied since the 1940s, it is far from being mature enough in comparison with the analysis method. In this work, the inverse problem method is improved by two aspects: the calculation accuracy and the strategy to determine the pressure loading distribution. The application of a high-quality mesh auto-generation and deformation technique to the inverse design is introduced. The no-slip wall boundary conditions, similar to the analysis model, and high-quality mesh, enable the use of an advanced turbulence model in the inverse design. These methods improve the accuracy of the inverse design. The loading distribution in the inverse design is obtained based on the boundary vorticity flux diagnosis. An axial fan is redesigned as an example of the inverse design method. The internal flow loss analysis based on the entropy production theory verifies the effectiveness of the inverse design used in this study.
An Experimental Methodology to Determine Components of Power Losses of a Gearbox
Authors: Dindar A. , Chaudhury K. , Hong I. , Kahraman A. , Wink C.
Published: January 2021

In this study, an experimental methodology is presented to separate various components of the power loss of a gearbox. The methodology relies on two separate measurements. One is designed to measure total power loss of a gearbox housing a single spur gear pair under both loaded and unloaded conditions such that load-independent (spin) and load-dependent (mechanical) components can be separated. With the assumption that gear pair and rolling element bearings constitute the bulk of the gearbox power loss, a second measurement system designed to quantify rolling element bearing losses is proposed. With this setup, spin and mechanical power losses of rolling element bearings used in the gearbox experiments are measured. Combining the sets of gearbox and bearing data, power loss components attributable to the gear pair and rolling element bearings are quantified as a function of speed and torque. The results indicate that all gear and bearing related components are significant and a methodology such as the one proposed in this study is warranted.
Novel Thrust Foil Bearing With Pocket Grooves for Enhanced Static Performance
Authors: LaTray Nguyen , Kim Daejong
Published: January 2021

The integration of foil bearing technology into high-speed oil-free machines has been slow in progress, in part, due to the low load-carrying capacity of the foil thrust bearing. It is crucial this issue is addressed through innovative solutions without overcomplicating the bearing design because simplicity is one of the attractive features of the foil bearing. This work presents novel thrust foil bearing with taper-flat configuration and pocket grooves on the bearing top foil as a secondary pressure boosting mechanism. Parametric study of the pocket dimensions on a rigid bearing reveals that the bearing static performance is the most sensitive to the pocket angular span. Further two-dimensional fluid–structure interaction analyses on foil thrust bearing predict a reduction of power loss by 10% with increased average film thickness. Minimum film thickness also increases when the bearing is lightly loaded but it is reduced 20% at the taper-flat transition area under high loading condition. This issue can be overcome by using stiffer bump foil; however, this is not implemented in this work due to other design constraints. Test results at 90,000 rpm and 140,000 rpm show, by adding the pocket groove pattern on the top foil, the power loss is reduced by 16% compared to the traditional taper-flat configuration.
Acoustic Beamforming Array Design Methods Over Irregular Shaped Areas
Authors: Arcondoulis Elias J. G. , Liu Yu
Published: January 2021

Acoustic beamforming array design methods are typically suited for circular and rectangular areas. A comparison of three array design methods is presented in this paper over irregular shaped areas, including L-shapes and arches. Partial-logarithmic spiral arrays that possess their geometric center either at the origin of the array area or the centroid of the irregular shaped area are compared against randomized array designs based on maximum sidelobe level (MSL) parameters and arrays generated using a recently published array design method named the adaptive array reduction method (AARM). In the AARM, a large array is reduced to a smaller array by seeking the removed microphone that possesses the minimum value of the MSL, the main lobe width (MLW), and a lobe distortion term. The AARM is also tested in two practical cases against a partial spiral array design used at the NASA Langley low-turbulence pressure tunnel and a hypothetical rectangular wall case. In both cases, the AARM showed superior performance to the logarithmic spiral arrays in all cases based on MSL and MLW criteria. Of the three methods compared, the AARM best utilizes the full potential array aperture of an irregular area and therefore produces the best MSL, MLW, and lobe distortion values.
Real-Time Driver Model Parameter Identification: An Algebraic Approach
Authors: Wang Zejiang , Wang Junmin
Published: January 2021

Advanced Driving Assistance System (ADAS) provides warning and automatic control intervention to a human driver for accident avoidance and collision mitigation. To simultaneously minimize the human-machine conflict and enhance human trust in the driving assistance system, ADAS should take personalized driving characteristics into account to support a particular driver in an optimal manner. Typical Personalized Driving Assistance System (PDAS) trains a driver model offline via complicated machine learning algorithms and assumes that the trained driver model maintains reliable until the next model retraining phase. However, even for a specific driver, its driving style can vary substantially due to various factors, e.g., daily mood variation, weather condition, and hardware adaption. To account for the time-varying feature of the driving style, the physics-based driver-model parameter identification has been applied to achieve an authentic PDAS. The commonly employed online driver model parameter identification approach is the Least Square (LS) method. However, LS, leaning on the classical Persistence of Excitation (PE) condition, may have slow estimation convergence. Alternatively, this paper proposes a purely algebraic method for driver model parameter identification. This new approach can achieve almost instantaneous multiple parameter identification. Moreover, by periodically resetting the proposed algebraic identifier, time-varying parameters of the driver model can also be captured online. Simulations demonstrate the excellent performance of the proposed algorithm.
State-Constrained Optimal Solutions for Safe Eco-Approach and Departure at Signalized Intersections
Authors: Han Jihun , Karbowski Dominik , Rousseau Aymeric
Published: January 2021

This paper provides fundamentals of how to energy-efficiently pass through signalized intersections while avoiding any rear-end collisions with leading vehicles. In our previous works [1, 2], analytical solutions with and without second-order pure state constraints imposed by the preceding vehicle were presented; these showed significant energy saving potential for connected and automated vehicles (CAVs) compared to human-driven vehicles. However, these solutions were derived assuming that the desired distance headway policy does not include a speed change over a predictive horizon, and that the preceding vehicle has constant acceleration. We use the desired time headway policy that includes the speed change to define the first-order pure state constraint. We then derive analytical solutions using the direct adjoining method based on Pontryagin’s minimum principle. We also present a novel solver to compute energy-optimal and collision-free state trajectories by accounting for a piecewise constant acceleration of the preceding vehicle without using any numerical optimization methods that require initial guesses. For simple scenarios with one intersection, we analyze how the novel solver allows CAVs to smoothly pass through the signalized intersection and then reach a desired cruising speed. We also use a simulation framework based on high-fidelity powertrain models to validate its effectiveness based on energy savings when driving on real-world urban routes.
Steerable Needle Trajectory Following in the Lung: Torsional Deadband Compensation and Full Pose Estimation With 5DOF Feedback for Needles Passing Through Flexible Endoscopes
Authors: Ertop Tayfun Efe , Emerson Maxwell , Rox Margaret , Granna Josephine , Webster Robert , Maldonado Fabien , Gillaspie Erin , Lester Michael , Kuntz Alan , Rucker Caleb , Fu Mengyu , Hoelscher Janine , Fried Inbar , Alterovitz Ron
Published: January 2021

Bronchoscopic diagnosis and intervention in the lung is a new frontier for steerable needles, where they have the potential to enable minimally invasive, accurate access to small nodules that cannot be reliably accessed today. However, the curved, flexible bronchoscope requires a much longer needle than prior work has considered, with complex interactions between the needle and bronchoscope channel, introducing new challenges in steerable needle control. In particular, friction between the working channel and needle causes torsional windup along the bronchoscope, the effects of which cannot be directly measured at the tip of thin needles embedded with 5 degree-of-freedom magnetic tracking coils. To compensate for these effects, we propose a new torsional deadband-aware Extended Kalman Filter to estimate the full needle tip pose including the axial angle, which defines its steering direction. We use the Kalman Filter estimates with an established sliding mode controller to steer along desired trajectories in lung tissue. We demonstrate that this simple torsional deadband model is sufficient to account for the complex interactions between the needle and endoscope channel for control purposes. We measure mean final targeting error of 1.36 mm in phantom tissue and 1.84 mm in ex-vivo porcine lung, with mean trajectory following error of 1.28 mm and 1.10 mm, respectively.
Hierarchical Multi-Timescale Energy Management for Hybrid-Electric Aircraft
Authors: Wang Wenqing , Koeln Justin P.
Published: January 2021

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

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

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

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

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

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

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

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

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.
Reduction of roadway noise in a coastal city underwater soundscape during COVID-19 confinement
Authors: Leon-Lopez Braulio , Romero-Vivas Eduardo , Viloria-Gomora Lorena
Published: January 2021

Confinement due to the COVID-19 pandemic drastically reduced human activities. Underwater soundscape variations are discussed in this study, comparing a typical and confinement day in a coastal lagoon near a popular tourist city in Mexico. Recording devices were located at 2 m in depth and 430 m away from the main promenade—a two-way avenue for light vehicle traffic—where main tourist infrastructure is located. The nearby marine environment is habitat to birds and dolphins as well as fish and invertebrates of commercial importance. Medium and small boats usually transit the area. The main underwater sound level reduction was measured at low frequencies (10–2000 Hz) because of the decrease in roadway noise. Vessel traffic also decreased by almost three quarters, although the level reduction due to this source was less noticeable. As typical day levels in the roadway noise band can potentially mask fish sounds and affect other low frequency noise-sensitive marine taxa, this study suggests that comprehensive noise analysis in coastal marine environments should consider the contribution from nearby land sources.
Reduced ATP-dependent proteolysis of functional proteins during nutrient limitation speeds the return of microbes to a growth state
Authors: Yeom Jinki , Groisman Eduardo A.
Published: January 2021

Protecting specific proteins from degradation enables
Salmonella
to rapidly recover from starvation.
Episodic exhumation of the Appalachian orogen in the Catskill Mountains (New York State, USA)
Authors: Shorten Chilisa M. , Fitzgerald Paul G.
Published: January 2021

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

Constraining 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 (<200 m) retain fissure-like features, with no vertical displacement for substantial parts of their displacement profiles. Typically, longer faults (>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.