bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation and Experiment Study of Gas-Liquid Two-Phase Flow Leakage in Horizontal Pipelines
Authors: Jian Ji 
Published: December 2019

Abstract
The influence of flow pattern, leakage location and leakage aperture changes on the flow field and the sound field in horizontal pipelines are studied in this paper. The CFD software is used to simulate the gas-liquid two-phase flow in horizontal pipes. Findings from literature research, it is necessary to study the change of flow field with different parameters in the simulation process. To study the flow field, first, a mathematical model of gas-liquid two-phase flow pipeline leakage established. The flow field parameters of gas-liquid two-phase flow is calculated under different gas&liquid inlet. Then, the fluent is used to solve the flow field, and the appropriate acoustic model is selected to realize the conversion of flow pattern to sound field. Finally, the simulation results are analyzed and verified through experiments. In this paper, we have simulated the change characteristics of the flow field and sound field of different flow pattern, leakage position, aperture size and the sound field, which is helpful to further understand and grasp the location and propagation law of the leakage source.
Analysis of the Velocity and Shear Stress of the Local Water-Diesel Flow System
Authors: Xu Guangli , Liu Tong , Niu Zhenyu , Cai Liangxue , Wang Menglong 
Published: December 2019

Abstract
The operation of pipelines has been affected by the corrosion caused by water deposited in some low sections of liquid products and natural gas pipeline. Flushing out the deposited water by flowing diesel has become a popular method. This research focused on a local water-diesel flow system with low Uos, in which the flow pattern, velocity and shear stress were analyzed through 2D simulation conducted by FLUENT software based on the grid independent strategy; meanwhile the simulations were verified by comparison with the published data.
Under the shear from flowing diesel with laminar flow, the flow pattern was found mainly as smooth and wavy stratified flow. The velocity of diesel phase becomes similar-parabolic distribution with an offset upwards in the radical direction, while there are reflux and eddy inside the residual water. Because of the presence of residual water, the shear stress of the walls become negative, and it increases along the two walls to the interface radically and increases to the maximum on the interface. The average velocity of residual water was found to increase linearly with the superficial velocity of oil flow.
Characterization of a Water-in-Waxy Crude Oil Emulsion by its Steady Apparent Viscosity
Authors: Guo Liping , Feng Tao , Liu Yang , Chen Xu , Li Wenbo , Hsu Jyh-Ping 
Published: December 2019

Abstract
The rheological properties of water-in-waxy crude oil emulsion depend highly on its forming conditions. Among these, the steady apparent viscosity is capable of characterizing its degree of emulsification. Adopting waxy crude oil in the field, we examine the influence of the water cut, the stirring speed, and the stirring time on the steady apparent viscosity of the emulsions formed under various conditions in this study. A model based on the viscous flow entropy generated in emulsion preparation is applied to correlate the steady apparent viscosity with the key parameters. A regression model is constructed for the dependence of the steady apparent viscosity on the viscous flow entropy, the shear rate, the rheological parameters of blank crude oil, and the wax deposition volume.
Influence of Inertia Terms on High Pressure Gap Flow Applications in Hydraulics
Authors: Fischer Felix , Rhein Andreas , Schmitz Katharina 
Published: December 2019

Abstract
Hydraulic pumps, which reach pressures up to 3000 bar, are often realized as plunger-piston type pumps. In the case of a common-rail pump for diesel injection systems, the plunger is driven by a cam-tappet construction and the contact during suction stroke is maintained by a helical spring. Many hydraulic piston-based high pressure pumps include gap seals, which are formed by small clearances between the two surfaces of the piston and the bushing. Usually the gap height is in the magnitude of several micrometers. Typical radial gaps are between 0.5 and 1 per mil of the nominal diameter. These gap seals are used to allow and maintain pressure build up in the piston chamber.
When the gap is pressurized, a special flow regime is reached. For the description of this particular flow the Reynolds equation, which is a simplification of the Navier-Stokes equations, can be used as done in the state of the art. Furthermore, if the pressure in the gap is high enough — 500 bar and above — fluid-structure interactions must be taken into account. Pressure levels above 1500 or 2000 bar indicate the necessity for solving the energy equation of the fluid phase and the rigid bodies surrounding it.
In any case, the fluid properties such as density and viscosity, have to be modelled in a pressure dependent manner. This means, a compressible flow is described in the sealing gap. Viscosity changes in magnitudes while density remains in the same magnitude, but nevertheless changes about 30 %. These facts must be taken into account when solving the Reynolds equation.
In this paper the authors work out that the Reynolds equation is not suitable for every piston-bushing gap seal in hydraulic applications. It will be shown that remarkable errors are made, when the inertia terms in the Navier-Stokes equations are neglected, especially in high pressure applications.
To work out the influence of the inertia terms in these flows, two simulation models are built up and calculated for the physical problem. One calculates the compressible Reynolds equation neglecting the fluid inertia. The other model, taking the fluid inertia into account, calculates the coupled Navier-Stokes equations on the same geometrical boundaries. Here, the so called SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm is used. The discretization is realized with the Finite Volume Method. Afterwards, the solutions of both models are compared to investigate the influence of the inertia terms on the flow in these specific high pressure applications.
Monitoring Digital Technologies in Hydraulic Systems Using CUSUM Control Charts
Authors: Breidi Farid , Chehade Abdallah , Lumkes John 
Published: December 2019

Abstract
Digital fluid power is a growing field which utilizes electronics and advanced controls to improve efficiencies, energy savings, and productivity in fluid power systems. Often relying on on/off high-speed switching techniques, digital hydraulics relies heavily on the performance of valves, where an error in the valve performance could lead to a major drop in the efficiency and performance of the entire system. Specifically, digital pump/motors are sensitive to valve delay and transition timing which negatively impacts their performance and condition with time. One approach to assessing the performance and efficiency of digital pump/motors is via monitoring its inlet (low) and outlet (high) pressure time-series. Real-time condition monitoring also supports preventive maintenance and provides a better understanding of the dynamics of pump/motors. For condition monitoring, Statistical Process Control (SPC) charts are often designed to detect shift changes in time-series. This paper proposes to construct two cumulative sum (CUSUM) control charts for fast real-time shift detection in the high and low pressure time-series of digital pump/motors. The proposed method will be able to actively detect common misbehaviors in the valves utilized in the digital pump/motor. The model have been successfully tested on a three-piston inline digital pump/motor, but this monitoring technique can be modified and implemented on other digital technology classes where valve performance is key in the success of the system.
Bio-Based Hydraulic Fluids in Mobile Machines: Substitution Potential in Construction Projects
Authors: Deuster Sebastian , Schmitz Katharina 
Published: December 2019

Abstract
This paper deals with the hydraulic oil consumption of mobile working machines. Different mobile working machines are going to be investigated by setting out their hydraulic oil consumption per hour. The substitutable amount of mineral by bio-based hydraulic oil is examined by an exemplary calculation for a construction project. The observations are intended to establish the working medium bio-based hydraulic oil on the lubricants market and to increase its use quantities, especially for mobile machines, with regard to environmental protection. Environmentally friendly lubricants and process materials are used in a wide variety of technical applications. In mobile machines in particular, efforts are being made to further establish bio-based lubricants. Due to unforeseeable accidents and leaks, a considerable amount of lubricants is released into the environment every year. This results in contamination of the affected environment. For this reason, contaminated ground, for example, has to be excavated refurbished after contact with hydraulic oil in order to return them to their original natural state. Bio-based hydraulic oils minimize this risk through their biodegradability and antitoxicity. Despite the proven performance of environmentally friendly hydraulic oil, the market share of biolubricants is stagnating at a constant and very low level. The majority of mobile machines use mineral oil, as working fluid in their hydraulic systems. To evaluate the substitution potential of mineral oil by bio-based oil in construction projects, various mobile machines are considered. In addition to widely used mobile machines like, for example excavators or wheel loaders, road construction equipment is also considered, due to a high hydraulic oil consumption resulting through heavy heat loads.
Modeling, Validation, and Investigation of an Electrohydraulic Crimping Hand Tool
Authors: Norquist Eric D. , Slightam Jonathon E. , Nagurka Mark L. 
Published: December 2019

Abstract
Due to their high power density, hydraulic systems are increasingly adapted for human scale devices. For example, commercial and utility electricians use electrohydraulic cutting and crimping tools, rather than human powered tools, to cut and crimp wires that exceed 25mm in diameter. These tools greatly reduce worker-related fatigue and strain-type injuries. To improve electrohydraulic tool technology, there is a need to increase the number of applications from a single battery charge. This paper develops a high fidelity nonlinear lumped parameter model of an electrohydraulic crimping hand tool used by professional electricians. The eleventh-order model can predict tool performance with an average error of 6.9% and 4.4% with respect to the maximum energy consumption and crimp time, respectively. Simulation studies were conducted to investigate reducing the energy consumption of the tool. An independent parameter sweep was performed on the pump piston diameter. The gear ratio was a dependent parameter linked through the maximum motor torque. Increasing the pump piston diameter while increasing the gear ratio was shown to decrease the energy consumption of the tool during crimping applications. Simulations suggest that up to 30% energy can be saved per crimp by increasing the pump piston diameter and gear train ratio.
Parameter Identification for Model-Based Control of Hydraulically Actuated Open-Chain Manipulators
Authors: Hulttinen Lionel , Koivumäki Janne , Mattila Jouni 
Published: December 2019

Abstract
In this paper, a nonlinear model-based controller with parameter identification is designed for a rigid open-chain manipulator arm actuated by servovalve-controlled hydraulic cylinders. The arising problem in adopting model-based controllers is how to acquire accurate estimates of system parameters, with limited available information about either the hydraulic actuator parameters or manipulator link inertial parameters. The objective of this study is to identify both the rigid-body parameters of the links and the hydraulic actuator parameters from collected cylinder chamber pressure and joint angle data, while no a priori knowledge of these parameters is available. Same physical plant models are used for control design as well as for parameter identification. Experimental results show that the proposed nonlinear model-based control scheme results in acceptable Cartesian position tracking performance in free-space motion when using the identified parameters.
Investigating Fault Detection and Diagnosis in a Hydraulic Pitch System Using a State Augmented EKF-Approach
Authors: Asmussen Magnus F. , Pedersen Henrik C. , Lilleengen Lina , Larsen Andreas , Farsakoglou Thomas 
Published: December 2019

Abstract
Pitch systems impose an important part of today’s wind turbines, where they are both used for power regulation and serve as part of a turbines safety system. Any failure on a pitch system is therefore equal to an increase in downtime of the turbine and should hence be avoided. By implementing a Fault Detection and Diagnosis (FDD) scheme faults may be detected and estimated before resulting in a failure, thus increasing the availability and aiding in the maintenance of the wind turbine. The focus of this paper is therefore on the development of a FDD algorithm to detect leakage and sensor faults in a fluid power pitch system.
The FDD algorithm is based on a State Augmented Extended Kalman Filter (SAEKF) and a bank of observers, which is designed utilizing an experimentally validated model of a pitch system. The SAEKF is designed to detect and estimate both internal and external leakage faults, while also estimating the unknown external load on the system, and the bank of observers to detect sensor drop-outs. From simulation it is found that the SAEKF may detect both abrupt and evolving internal and external leakages, while being robust towards noise and variation in system parameters. Similar it is found that the scheme is able to detect sensor drop-outs, but is less robust towards this.
Improving the Efficiency and Dynamic Properties of a Flow Control Unit in a Self-Locking Compact Electro-Hydraulic Cylinder Drive
Authors: Schmidt Lasse , Ketelsen Søren , Padovani Damiano , Mortensen Kasper Aa. 
Published: December 2019

Abstract
The introduction of low cost electric motor and drive solutions provides the possibility to design cost competitive compact speed-variable drives as potentially feasible alternatives to conventional valve-controlled solutions. A main drawback in existing self-contained drive technology is the power consumption in stationary load carrying situations. However, the recent introduction of compact self-locking drive topologies with separate forward and return flow lines allow to significantly minimize the power consumption, but introduces another problem. Dependent on the control of the flow device, a continuous, but lower power consumption compared to non-self-locking drive topologies may be present. Furthermore, the piston motion may exhibit a time delay due to an outlet pressure build-up phase in the flow unit prior to actuation of the cylinder, limiting the application range of such a drive concept. The purpose of the study presented, is to analyze these properties through model-based methods, and to establish control functionalities allowing to minimize these unfortunate features. The resulting flow device control structure allows for a significant reduction in the actuation time delay as well as in the power consumption in stationary load carrying situations. Numerical results demonstrate the properties announced by the theoretical analysis and control design phase, hence broadening the application range of the self-locking drive topology in question.
Concept Studies on a Multifunctional Unit for Hydraulic Supply and High Lift Actuation in Aircraft
Authors: Nordmann Lennard , Thielecke Frank , Lücken Peter , Hamm Martin 
Published: December 2019

Abstract
This paper investigates the potential of a new functionality of the hybrid Power Control Unit (PCU) in zonal electrohydraulic aircraft systems. The conventional PCU, as a hydraulic consumer, is the central drive for the leading and trailing edge flaps of an aircraft. Through extended functionality, it can also be operated as pump to provide hydraulic power in certain flight phases. The paper elaborates and presents different concepts for the integration of such a multifunctional PCU and evaluates the potential regarding mass savings and improvement of reliability. In subsequent simulation studies, the most promising concept is validated and analysed regarding the arising challenges.
Application of Data Reduction Techniques to Dynamic Condition Monitoring of an Axial Piston Pump
Authors: Wiens Travis , Fernandes Jon 
Published: December 2019

Abstract
Condition monitoring of axial piston pumps has seen considerable research in recent years, due to the attractive economic benefits of predictive pump maintenance rather than unscheduled failures. Often the health of the pump is well correlated to leakage, but directly measuring flow can be expensive and unreliable. Instead, some researchers have proposed using dynamic pressure measurements to infer leakage parameters, with some success. One of the major impediments to widespread adoption of this method is that large volumes of data are required to generate a useful model relating the dynamic measurements to leakage parameters, typically with high sensitivity to noise and prone to overfitting. This paper applies data dimensionality reduction techniques to this problem and evaluates their usefulness using a simulation study.
Diffusion tensor imaging in neonatal encephalopathy: a systematic review
Authors: Dibble Megan , O"Dea Mary Isabel , Hurley Tim , Byrne Angela , Colleran Gabrielle , Molloy Eleanor J , Bokde Arun Lawrence Warren 
Published: December 2019

Background and objectiveDiffusion tensor imaging (DTI) during the first few days of life can be used to assess brain injury in neonates with neonatal encephalopathy (NE) for outcome prediction. The goal of this review was to identify specific white matter tracts of interest that can be quantified by DTI as being altered in neonates with this condition, and to investigate its potential prognostic ability.MethodsSearches of Medline and the Cochrane Database of Systematic Reviews were conducted to identify studies with diffusion data collected in term-born neonates with NE.Results19 studies were included which described restricted diffusion in encephalopathic neonates as compared with healthy controls, with the posterior limb of the internal capsule and the genu and splenium of the corpus callosum identified as particular regions of interest. Restricted diffusion was related to adverse outcomes in the studies that conducted a follow-up of these infants.ConclusionsObtaining diffusion measures in these key white matter tracts early in life before pseudonormalisation can occur can not only identify the extent of the damage but also can be used to examine the effectiveness of treatment and to predict neurodevelopmental outcome.
Mechanism of fluid leak in non-traumatic corneal perforations: an anterior segment optical coherence tomography study
Authors: AlMaazmi Amna , Said Dalia G , Messina Marco , AlSaadi Ahmed , Dua Harminder Singh 
Published: December 2019

Aim
Non-traumatic corneal perforations (CPerfs) may present with shallow/flat or formed anterior chamber (AC). This study uses anterior segment optical coherence tomography (ASOCT) to ascertain these differences.

Method
The study included 14 eyes of 13 patients. They underwent high-resolution ASOCT scans at multiple time points, prior to and after cyanoacrylate glueing, between January 2016 and July 2018. A retrospective analysis of over 2500 ASOCT sections and AS photographs was conducted by two independent observers. The findings were correlated with clinical features and diagnoses.

Result
All patients had documented Seidel’s positive sign at the outset. Two groups with distinctive features were identified. In group 1, ‘formed’ AC, there was hydration of the cornea with lamellar separation of the stroma, intrastromal pockets of fluid, epithelial bullae and an indirect communication between AC and the exterior. In group 2, ‘flat’ AC, the corneal hydration was less obvious, there were no pockets of intrastromal fluid, no epithelial bullae and a direct communication of the AC with the exterior. After glueing, the stromal hydration resolved, and healing occurred beneath the glue. The glue and corneal blood vessels consistently cast a dense shadow posteriorly on ASOCT.

Conclusion
ASOCT demonstrates that leaking CPerfs can be indirect or direct. The former is associated with a ‘formed’ AC and the latter with a very shallow/flat AC. The valvular nature of the communication in indirect perforations allows the AC to maintain its volume despite a continuous leak.
Implementing a junior high school-based programme to reduce sports injuries through neuromuscular training (iSPRINT): a cluster randomised controlled trial (RCT)
Authors: Emery Carolyn A , van den Berg Carla , Richmond Sarah Ann , Palacios-Derflingher Luz , McKay Carly D , Doyle-Baker Patricia K , McKinlay Megan , Toomey Clodagh M , Nettel-Aguirre Alberto , Verhagen Evert , Belton Kathy , Macpherson Alison , Hagel Brent E 
Published: December 2019

ObjectiveTo evaluate the effectiveness of a junior high school-based sports injury prevention programme to reduce injuries through neuromuscular training (NMT).MethodsThis was a cluster randomised controlled trial. Students were recruited from 12 Calgary junior high schools (2014–2017). iSPRINT is a 15 min NMT warm-up including aerobic, agility, strength and balance exercises. Following a workshop, teachers delivered a 12-week iSPRINT NMT (six schools) or a standard-of-practice warm-up (six schools) in physical education classes. The definition of all recorded injuries included injuries that resulted in participants being unable to complete a sport and recreation (S&R) session, lost time from sport and/or seek medical attention. Incidence rate ratios (IRRs) were estimated based on multiple multilevel Poisson regression analyses (adjusting for sex (considering effect modification) and previous injury, offset by S&R participation hours, and school-level and class-level random effects were examined) for intent-to-treat analyses.Results1067 students (aged 11–16) were recruited across 12 schools (6 intervention schools (22 classes), 6 control schools (27 classes); 53.7% female, 46.3% male). The iSPRINT programme was protective of all recorded S&R injuries for girls (IRR=0.543, 95% CI 0.295 to 0.998), but not for boys (IRR=0.866, 95% CI 0.425 to 1.766). The iSPRINT programme was also protective of each of lower extremity injuries (IRR=0.357, 95% CI 0.159 to 0.799) and medical attention injuries (IRR=0.289, 95% CI 0.135 to 0.619) for girls, but not for boys (IRR=1.055, 95% CI 0.404 to 2.753 and IRR=0.639, 95% CI 0.266 to 1.532, respectively).ConclusionThe iSPRINT NMT warm-up was effective in preventing each of all recorded injuries, lower extremity injuries and medically treated S&R injuries in female junior high school students.Trial registration numberNCT03312504