bluuebunny/crossref_metadata_2025_split huggingface dataset:
Implementation of Bubble Dynamic Effects by Coupling the Gilmore Equation With Fluid Dynamic Equations Using the Method of Characteristics
Authors: Guse Fabian , Pasquini Enrico , Schmitz Katharina 
Published: October 2020

Abstract
In fluid power systems, performance as well as system dynamics are strongly influenced by the presence of bubbles — especially for low system pressures. While the static effect of dissolved air (especially the volume fraction of dissolved air) on the bulk modulus has been extensively investigated in the past, in hydraulics, the dynamic effects due to bubble dynamics have been neglected entirely.
Thereby, the dynamic characteristics of the bubbles influence the compressibility of the disperse fluid and, as a consequence, the speed of sound in the mixture and the hydraulic system as a whole. In order to account for the bubble behavior in hydraulic simulation models, the present paper investigates a method for coupling bubble dynamics equations, such as the Gilmore or the Rayleigh-Plesset equation, with the fluid dynamic equations and their subsequent solution using the method of characteristics. Regarding the modeling, special attention is put on the distributed bubble nuclei sizes, since bubbles of the exact same size are unnatural and cannot be observed in reality. Since a dilute mixture — i.e. a small void fraction — is assumed, bubble-bubble interaction is neglected in this study. To account for the polydispersity, a discretized lognormal distribution for equilibrium bubble sizes is considered. In order to evaluate the discretization interval needed, case studies of different numbers of bubble size classes are presented and their results evaluated. Thereby, the question about the least required numbers of homogeneous bubble clusters shall be answered, as to reduce the computational effort that is needed. Using the method described in this paper, the profound effect of the bubble dynamics and the bubble size distribution on the fluid system dynamics is elaborated.
Fluid Property Effects on Power Consumption in a Hydraulic System at Low Temperatures
Authors: Michael Paul , Dai Cecilia , Rodriguez Kimberly 
Published: October 2020

Abstract
Hydraulic systems that are operated outdoors during winter can be exposed to extreme low temperatures. Low temperature thickening of the hydraulic fluid can increase power consumption, cause pump cavitation, and stall system actuation. In this study, the response time and power consumption of a hydraulic vehicle restraint system that is used outdoors year-round was evaluated at low temperatures. This safety device incorporated proximity switches that triggered a machine “fault” when the time delay between the locked and unlocked positions exceeded 8 seconds. Straight- and multi-grade ISO VG 32 and 46 fluids were compared in the device. The multi-grade oils were able to function at a lower temperature without faulting. The effect of system operating conditions and fluid properties on pump input power was evaluated. The input power was determined from measurements of pump rotational frequency and torque. Pump torque increased as the oil temperature decreased. As a result, low-temperature operating conditions resulted in a higher system power requirements. An empirical model was developed to investigate the effects of turbulent and laminar flow conditions on the hydraulic system power requirements. A comparison of model standard errors revealed that viscosity-dependent laminar losses had a greater impact on system performance than density-dependent turbulent losses. Since the viscosity coefficients of the fluids were very high at the test temperature, it was theorized that pressure drop in the hydraulic lines was affecting system response. Hydraulic system simulations were conducted via Automation Studio. Cylinder retraction velocities were evaluated with larger ID cap- and rod-side hoses. Increasing the cap-side hose diameter enhanced the low temperature performance of the system. Changes to the rod-side hose had minimal effect. These results provide new insights for system design and the formulation of hydraulic fluids used in extreme low temperature operations.
Experimental Validation of Leakage Detection in a Fluid Power Pitch System Using a State Augmented EKF-Approach
Authors: Asmussen Magnus F. , Pedersen Henrik C. , Liniger Jesper 
Published: October 2020

Abstract
The pitch system is a crucial part of today’s wind turbines and is used for power regulation when operating above rated wind speed. According to studies the pitch system is responsible for up to 20% of the total downtime of a wind turbine. As an attempt of increasing the reliability and availability attention has come to fault detection and condition monitoring of such systems. This paper presents a State Augmented Extended Kalman Filter, SAEKF, for detecting both internal and external rod leakage. Furthermore, an external load torque is included in the filter to improve the performance in the presence of external load. The SAEKF is tested experimentally for different levels of both internal and external rod leakage under working conditions similar to the ones experienced for a pitch system located in a wind turbine. The working conditions include unkown fast varying external loads. The experiments show that the SAEKF is capable of detecting internal and external leakage down to 0.10 l/min and 0.34 l/min, respectively. The internal leakage is detected with a estimation error of maximum 0.04 l/min while the external leakage estimation error is going up to 0.43 l/min for high levels of external leakage.
Condition Monitoring Strategy for Pump-Driven Hydraulic Axes
Authors: Schraft Jacques Philippe , Becher Dirk , Weber Jürgen 
Published: October 2020

Abstract
Electrohydrostatic Actuation Systems (EAS) are characterized by an Electrohydrostatic Pump Unit (EPU) that directly drives a hydraulic actuator. This motion concept combines both advantages of traditional electro-mechanical actuation and electro-hydraulic actuation like high energy efficiency, environmental cleanliness, low noise emission, high force output, and no backslash. In modern IoT/I4.0 environments, the utilization of digital data plays a more and more important role such as histories of sensor data, of working cycles, or of the machine health status. In the example of an EAS, a way is shown to monitor the health status of the integrated hydrostatic machine along with the hydraulic part of such an EAS. The approach described in this paper uses the already existing sensors in an EAS, so no additional hardware is necessary. Based on a model describing the volumetric behaviour of the hydrostatic machine a volumetric health index is developed by introducing a re-normalized efficiency. The proposed methodology is independent on the overall working cycle and is therefore applicable to already running systems or systems with varying working cycle. The calculated Health Index offers the opportunity to monitor the hydrostatic machine as the key element of such an EAS in real time and in a non-invasive and continuous way.
Online Parameter Estimation of Hydraulic System Based on Stochastic Gradient Descent
Authors: Yamada Takashi , Howard Matthew 
Published: October 2020

Abstract
In this paper, offline and online parameter estimation methods for hydraulic systems based on stochastic gradient descent are presented. In contrast to conventional approaches, the proposed methods can estimate any parameter in mathematical models based on multi-step prediction error. These advantages are achieved by calculating the gradient of the multi-step error against the estimated parameters using Lagrange multipliers and the calculus of variations, and by forming differentiable models of hydraulic systems. In experiments on a physical hydraulic system, the proposed methods with three different gradient decent methods (normal gradient descent, Nesterov’s Accelerated Gradient (NAG), and Adam) are compared with conventional least squares. In the offline experiment, the proposed method with NAG achieves estimation error about 95% lower than that of least squares. In online estimation, the proposed method with NAG produces predictive models with about 20% lower error than that of the offline method. These results suggest the proposed method is a practical alternative to more conventional parameter estimation methods.
Hopsan: An Open-Source Tool for Rapid Modelling and Simulation of Fluid and Mechatronic Systems
Authors: Braun Robert , Nordin Peter , Ericson Liselott , Larsson L. Viktor , Krus Petter , Pettersson Maria 
Published: October 2020

Abstract
Hopsan is an open-source simulation package developed as a collaboration project between industry and academia. The simulation methodology is based on transmission line modelling, which provides several benefits such as linear model scalability, numerical robustness and parallel simulation. All sub-models are pre-compiled, so that no compilation is required prior to starting a simulation. Default component libraries are available for hydraulic, mechanic, pneumatic, electric and signal domains. Custom components can be written in C++ or generated from Modelica and Mathematica. Support for simulation-based optimization is provided using population-based, evolutionary or direct-search algorithms. Recent research has largely focused on co-simulation with other simulation tools. This is achieved either by using the Functional Mock-up Interface standard, or by tool-to-tool communications. This paper provides a description of the program and its features, the current status of the project, and an overview of recent and ongoing use cases from industry and academia.
Parameter Identification of Hydraulic Systems Using Modified Coyote Optimization Algorithm
Authors: Mohammadi Asl Reza , Handroos Heikki 
Published: October 2020

Abstract
Parameter identification is one of most interesting fields for researchers in control engineering field. Different methods have been investigated in recent years. Methods can be divided into two main categories: mathematical based methods and artificial intelligence approaches. Mathematical approaches also known as traditional method which uses different formula to have an estimation of some missed parameters in practical systems, and on the other hand artificial intelligence methods uses different approaches for this purpose. This paper presents a new parameter identification method. A new modified evolutionary algorithm, which can be sorted as a approach of artificial intelligence, is presented and applied to a servo-hydraulic system as a parameter identification method. Coyote Optimization algorithm is chosen for this purpose. The presented modified algorithm is changed in a way that in each iteration, uses details from previous steps and have a better performance in comparison with the basic algorithm. The proposed algorithm tries to update each candidate based on its previous condition which has been missed in basic algorithm. The proposed intelligent method is used as parameter identification method and applied to servo-hydraulic system. The results for simulation are given. Results show the efficiency of the presented method. Based on results, it can be drawn that the proposed method can be supposed as reliable method for nonlinear systems.
Adaptive Integral Non-Singular Terminal Sliding Mode Control of a Servo-Hydraulic System
Authors: Shabbouei Hagh Yashar , Mohammadi Asl Reza , Handroos Heikki 
Published: October 2020

Abstract
This paper proposes an adaptive integral non-singular terminal sliding mode control in combination with a neural network (INTSMC-NN) for nonlinear servo-hydraulic actuator systems. The proposed controller has the advantages of the conventional non-singular terminal sliding mode control; it can tolerate external disturbances, evades the singularity problem of the conventional terminal sliding mode control, and also guarantees finite time convergence of states. The main problem and drawback of the sliding mode-based control is the chattering phenomenon which is caused by the switching part of the controller. This phenomenon can cause severe impacts on mechanical components of the hydraulic system. In order to overcome to this issue, and moderate the control signal, the discontinuous part of the controller is replaced by a neural network. The stability of the controller is investigated through Lyapunov stability criteria. To study the performance of the proposed INTSMC in combination with neural network a third-order nonlinear servo-hydraulic actuator is considered. Simulation results first, indicates the capability of the proposed method in eliminating the chattering from the control signal and also making the system states to track the desired trajectory with high accuracy. Second, the performance of the proposed integral NTSMC is studied and compared to the conventional NTSMC.
Students 4 Best Evidence as a digital Problem-Based Learning method to improve Evidence-Based Practice competencies in undergraduate physiotherapy students: an observational study
Authors: Arienti Chiara , Lazzarini Stefano Giuseppe , Pollet Joel , Negrini Stefano 
Published: October 2020

Background
Evidence-based practice (EBP) is an essential element in the delivery of high-quality care and healthcare professionals make clinical decisions based on the best available research. Experts and international organisations have emphasised the need for healthcare professionals to possess adequate competencies for EBP. An EBP learning laboratory has been established at an Italian university to educate medical and other health professional students in the use of evidence in clinical practice and research. Students 4 Best Evidence (S4BE) is an online community of students from around the world, from school age to university, who are interested in learning more about EBP. As well as featuring a library of learning resources, the site also provides a platform for students to write their own blogs.

Objectives
The aim of this study is to evaluate the effectiveness of an EBP laboratory, using S4BE as an educational tool, to teach EBP competencies to undergraduate physiotherapy students.

Design
We ran an observational pretest and post-test study.

Participants and setting
The sample included 121 students completing a bachelor’s degree in Physiotherapy at an Italian University.

Intervention
The intervention consisted of using the S4BE platform as the digital Problem-Based Learning (DPBL) method to teach EBP competencies.

Main outcome measures

Results
The students showed a significant improvement in all domains (p<0.001), except in the sympathy domain, where the percentage score decreased from 71% to 60%. The best improvements were reached in terminology (54% to 65%) and in practice (41% to 55%) domains.

Conclusion
This study proposed an effective educational protocol, based on a DPBL approach, using S4BE as a digital technology tool. Further research is needed to test the effectiveness of this educational protocol compared with traditional learning methods for physiotherapy students.

Trial registration number

NCT03707119
.
Reproductive patterns, pregnancy outcomes and parental leave practices of women physicians in Ontario, Canada: the Dr Mom Cohort Study protocol
Authors: Cusimano Maria C , Baxter Nancy N , Sutradhar Rinku , Ray Joel G , Garg Amit X , McArthur Eric , Vigod Simone , Simpson Andrea N 
Published: October 2020

IntroductionSurveys and qualitative studies suggest that women physicians may delay childbearing, be at increased risk of adverse peripartum complications when they do become pregnant, and face discrimination and lower earnings as a result of parenthood. Observational studies enrolling large, representative samples of women physicians are needed to accurately evaluate their reproductive patterns, pregnancy outcomes, parental leave practices and earnings. This protocol provides a detailed research plan for such studies.Methods and analysisThe Dr Mom Cohort Study encompasses a series of retrospective observational studies of women physicians in Ontario, Canada. All practising physicians in Ontario are registered with the College of Physicians and Surgeons of Ontario (CPSO). By linking a dataset of physicians from the CPSO to existing provincial administrative databases, which hold health data and physician billing records, we will be able to retrospectively assess the healthcare utilisation, work practices and pregnancy outcomes of women physicians at the population level. Specific outcomes of interest include: (1) rates and timing of pregnancy; (2) pregnancy-related care and complications; and (3) duration of parental leave and subsequent earnings, each of which will be evaluated with regression methods appropriate to the form of the outcome. We estimate that, at minimum, 5000 women physicians will be eligible for inclusion.Ethics and disseminationThis protocol has been approved by the Research Ethics Board at St. Michael’s Hospital in Toronto, Ontario, Canada (#18–248). We will disseminate findings through several peer-reviewed publications, presentations at national and international meetings, and engagement of physicians, residency programmes, department heads and medical societies.
Experience of fatigue and associated factors among adult people living with HIV attending ART clinic: a hospital-based cross-sectional study in Ethiopia
Authors: Baye Moges , Fisseha Berihu , Bayisa Mulugeta , Abebe Solomon Mekonnen , Janakiraman Balamurugan 
Published: October 2020

ObjectiveThis study aimed to determine the prevalence of fatigue and the factors associated among adult people living with HIV attending antiretroviral therapy clinic in Gondar town, Ethiopia.DesignCross-sectional.SettingGovernmental health facility that provides HIV care in Gondar town.Outcome measureFatigue is defined by nine items version Fatigue Severity Scale.ParticipantsAdult (aged 18 and above) people living with HIV in Gondar town (n=392).ResultA total of 408 HIV seropositive adults were approached for consent, among which 392 participants consented to participate in this study, with a response rate of 96.1%. The mean age of the participants was 40.5±8.5 years. The prevalence of HIV-related fatigue was 53.3% and about 66% of women living with HIV experienced fatigue. The factors associated with fatigue experience were; female gender (adjusted OR (AOR): 2.61, 95% CI 1.01 to 5.3), being married (AOR: 0.18, 95% CI 0.10 to 0.9), low income (AOR: 7.1, 95% CI 4.6 to 22.15), unemployed (AOR: 2.79, 95% CI 1.19 to 9.84), parity (AOR: 4.87, 95% CI 2.18 to 17.9), being anaemic (AOR: 12.45, 95% CI 5.6 to 41.01), depression (AOR: 4.51, 95% CI 1.91 to 11.20), mild weight loss (AOR: 4.2 95% CI 2.56 to 13.9) and moderate weight loss (AOR: 5.1, 95% CI 1.85 to 16.12), respectively.ConclusionThe findings of this study revealed that experiencing fatigue is quite common among adult people living with HIV. It is important for the healthcare professionals and people living with HIV to understand; the possible causes of fatigue, remedies and ways to reclaim energy. The predisposing factors and complications that cause fatigue should be aggressively diagnosed and treated by the clinicians. Further qualitative studies exploring the reasons for experiencing HIV-related fatigue might help designing interventions.
Longus capitis and rectus capitis ventralis minor rupture in a horse following general anaesthesia for a laryngeal tie‐forward procedure
Authors: Thomas Imogen , Dixon Jonathon J , Fraser Barny 
Published: October 2020

The authors present a case of a racehorse with acute respiratory distress, bilateral epistaxis and laryngeal swelling following a laryngeal tie‐forward procedure. An emergency tracheostomy was performed following brief endoscopic examination identifying significant pharyngeal collapse and a minimally patent airway. No cranial nerve deficits or obvious neurological abnormalities were present. Lateral radiographs ruled out a fracture and provided a preliminary diagnosis of hyperextension injury. CT 24 hours later showed marked soft tissue swelling consistent with haemorrhage associated with the ventral straight muscles, causing median septum disruption. No fractures were identified. Endoscopy four days postoperatively confirmed the haemorrhage was external to the guttural pouches consistent with ventral straight muscle rupture. The horse was treated conservatively with five weeks of box rest. The tracheostomy tube was removed 19 days postoperatively. The horse was then discharged and gradually returned to exercise, winning a race nine months later.
Tectonic evolution in the Early to Middle Pleistocene off the east coast of the Boso Peninsula, Japan
Authors: Furuyama Seishiro , Sato Tomoyuki , Arai Kohsaku , Ozaki Masanori 
Published: October 2020

Abstract

The Kanto Basin developed, starting
c.
3 Ma, influenced by the subduction of the Philippine Sea plate and the Pacific plate. Sediments in this basin have influenced the geomorphology of the Kanto region. In the Boso Peninsula, located at the eastern edge of the Kanto Basin, uplift continues in what is called the Kashima–Boso uplift zone. Although the development of this uplift after the Late Pleistocene is well understood, there are few data from the Early to Middle Pleistocene. In this study, we investigated the offshore shelf area east of the Boso Peninsula using a high-resolution seismic reflection survey, and report new information on the geological structure and uplift processes in the area from the Early to Middle Pleistocene. We identified the Kujukuri-oki anticline and the Kujukuri-oki normal fault zone. The Kujukuri-oki anticline, more than 47 km long, is north–south striking and deforms the Kujukuri-oki Group. There are numerous normal faults with displacements of less than tens of metres spread widely in the survey area (Kujukuri-oki normal fault zone). These findings reveal that the Kujukuri-oki anticline uplifted during the end of the Early Pleistocene and attenuated during the Middle Pleistocene. This anticline comprised the axis of the Kashima–Boso uplift zone at the Boso Peninsula from the Early to Middle Pleistocene and the Boso Peninsula is located at the western limb of this anticline.
Programming Strategies for Irregular Algorithms on the Emu Chick
Authors: Hein Eric R. , Eswar Srinivas , Yaşar Abdurrahman , Li Jiajia , Young Jeffrey S. , Conte Thomas M. , Çatalyürek Ümit V. , Vuduc Richard , Riedy Jason , Uçar Bora 
Published: October 2020

The Emu Chick prototype implements migratory memory-side processing in a novel hardware system. Rather than transferring large amounts of data across the system interconnect, the Emu Chick moves lightweight thread contexts to near-memory cores before the beginning of each remote memory read. Previous work has characterized the performance of the Chick prototype in terms of memory bandwidth and programming differences from more typical, non-migratory platforms, but there has not yet been an analysis of algorithms on this system.
This work evaluates irregular algorithms that could benefit from the lightweight, memory-side processing of the Chick and demonstrates techniques and optimization strategies for achieving performance in sparse matrix-vector multiply operation (SpMV), breadth-first search (BFS), and graph alignment across up to eight distributed nodes encompassing 64 nodelets in the Chick system. We also define and justify relative metrics to compare prototype FPGA-based hardware with established ASIC architectures. The Chick currently supports up to 68x scaling for graph alignment, 80 MTEPS for BFS on balanced graphs, and 50% of measured STREAM bandwidth for SpMV.