bluuebunny/crossref_metadata_2025 huggingface dataset:
A preprocessing tool for removing artifact from cardiac RR interval recordings using three‐dimensional spatial distribution mapping
Authors: Stapelberg Nicolas J. C. , Neumann David L. , Shum David H. K. , McConnell Harry , Hamilton‐Craig Ian
Published: January 2016

Artifact is common in cardiac RR interval data that is recorded for heart rate variability (HRV) analysis. A novel algorithm for artifact detection and interpolation in RR interval data is described. It is based on spatial distribution mapping of RR interval magnitude and relationships to adjacent values in three dimensions. The characteristics of normal physiological RR intervals and artifact intervals were established using 24‐h recordings from 20 technician‐assessed human cardiac recordings. The algorithm was incorporated into a preprocessing tool and validated using 30 artificial RR (ARR) interval data files, to which known quantities of artifact (0.5%, 1%, 2%, 3%, 5%, 7%, 10%) were added. The impact of preprocessing ARR files with 1% added artifact was also assessed using 10 time domain and frequency domain HRV metrics. The preprocessing tool was also used to preprocess 69 24‐h human cardiac recordings. The tool was able to remove artifact from technician‐assessed human cardiac recordings (sensitivity 0.84, SD = 0.09, specificity of 1.00, SD = 0.01) and artificial data files. The removal of artifact had a low impact on time domain and frequency domain HRV metrics (ranging from 0% to 2.5% change in values). This novel preprocessing tool can be used with human 24‐h cardiac recordings to remove artifact while minimally affecting physiological data and therefore having a low impact on HRV measures of that data.
Socio‐cultural dynamics shaping the potential of aquaculture to deliver development outcomes
Authors: Morgan Miranda , Terry Geraldine , Rajaratnam Surendran , Pant Jharendu
Published: January 2016

There is growing appreciation of the role of aquaculture in diversifying livelihoods of the poor. However, prevailing cultural norms and values, and social relations often influence its development outcomes, which we explore in this study. Socio‐cultural dynamics affect the capacity of resource‐poor and marginalized groups for the adoption and retention of aquaculture technologies. Gender norms and gender division of labour in a given community not only influence whether men or women participate in aquaculture but also shape their differential access to resources and position in decision‐making, with knock‐on effect for aquaculture productivity. Ethnic and cultural norms of collectivism, particularly in traditional fishing communities, support aquaculture efforts, but these are often overlooked by many development endeavours. Improved productivity does not necessarily translate into enhanced income, food and nutrition security. In many areas, benefits for women are lower despite their more active participation in aquaculture operations, post‐harvest processing and marketing compared to men. Local power relations may limit access to land and water resources as well as inputs and services by the poor, restricting more equitable distribution of income from aquaculture. Nutritional outcome from aquaculture largely depends on preferences and acceptability of fish as a food and local customs regarding its preparation, preservation, cooking and distribution. Aquaculture interventions that take resource base and socio‐cultural contexts into account are crucial for realizing increased income, food and nutrition benefits sustainably.
Silencing the porcine iGb3s gene does not affect Galα3Gal levels or measures of anticipated pig‐to‐human and pig‐to‐primate acute rejection
Authors: Butler James R. , Skill Nicholas J. , Priestman David L. , Platt Frances M. , Li Ping , Estrada Jose L. , Martens Gregory R. , Ladowski Joseph M. , Tector Matthew , Tector A. Joseph
Published: January 2016

Background

The Galα(1,3)Gal epitope (α‐GAL), created by α‐1,3‐glycosyltransferase‐1 (GGTA1), is a major xenoantigen causing hyperacute rejection in pig‐to‐primate and pig‐to‐human xenotransplantation. In response, GGTA1 gene‐deleted pigs have been generated. However, it is unclear whether there is a residual small amount of α‐Gal epitope expressed in GGTA1−/− pigs. Isoglobotrihexosylceramide synthase (iGb3s), another member of the glycosyltransferase family, catalyzes the synthesis of isoglobo‐series glycosphingolipids with an α‐GAL‐terminal disaccharide (iGb3), creating the possibility that iGb3s may be a source of α‐GAL epitopes in GGTA1−/− animals. The objective of this study was to examine the impact of silencing the iGb3s gene (A3GalT2) on pig‐to‐primate and pig‐to‐human immune cross‐reactivity by creating and comparing GGTA1−/− pigs to GGTA1−/−‐ and A3GalT2−/−‐double‐knockout pigs.

Methods

We used the CRISPR/Cas 9 system to target the GGTA1 and A3GalT2 genes in pigs. Both GGTA1 and A3GalT2 genes are functionally inactive in humans and baboons. CRISPR‐treated cells used directly for somatic cell nuclear transfer produced single‐ and double‐gene‐knockout piglets in a single pregnancy. Once grown to maturity, the glycosphingolipid profile (including iGb3) was assayed in renal tissue by normal‐phase liquid chromatography. In addition, peripheral blood mononuclear cells (PBMCs) were subjected to (i) comparative cross‐match cytotoxicity analysis against human and baboon serum and (ii) IB4 staining for α‐GAL/iGb3.

Results

Silencing of the iGb3s gene significantly modulated the renal glycosphingolipid profile and iGb3 was not detected. Moreover, the human and baboon serum PBMC cytotoxicity and α‐GAL/iGb3 staining were unchanged by iGb3s silencing.

Conclusions

Our data suggest that iGb3s is not a contributor to antibody‐mediated rejection in pig‐to‐primate or pig‐to‐human xenotransplantation. Although iGb3s gene silencing significantly changed the renal glycosphingolipid profile, the effect on Galα3Gal levels, antibody binding, and cytotoxic profiles of baboon and human sera on porcine PBMCs was neutral.
Public Knowledge and Attitudes Regarding the Use of Antibiotics and Resistance: Findings from a Cross‐Sectional Study Among Palestinian Adults
Authors: Abu Taha A. , Abu‐Zaydeh A. H. , Ardah R. A. , Al‐Jabi S. W. , Sweileh W. M. , Awang R. , Zyoud S. H.
Published: January 2016

Antibiotics are considered to be among the most commonly sold drug classes in Palestine. Resistance to antibiotics has increased for reasons relating to the use and misuse of antibiotics. The aim of this study was to evaluate the knowledge, and attitudes regarding antibiotic use and awareness about resistance among adults visiting the emergency departments at hospitals in North Palestine. A self‐administered cross‐sectional questionnaire survey involving participants aged 18 or over was conducted from June 2012 to February 2013. Adults who visited the emergency departments at hospitals in North Palestine were included. Demographic characteristics, knowledge and attitudes towards antibiotic use were included in the questionnaire. Poor and good knowledge were defined as a total knowledge score of 0–7 and 8–15 of 15 questions, respectively. Attitude scores of 0–3 and 4–7 of 7 questions were considered poor and good, respectively. A total of 375 questionnaires were included in the study. A response rate of 83.3% was attained. About 55.0% of the participants had a good knowledge and 56.5% had a good attitude towards rational antibiotic use. A significant positive correlation was shown between participants’ knowledge scores and participants’ attitude scores towards antibiotic use (R = 0.344, P = 0.001. Participants with a high family income were more likely to be aware of appropriate antibiotic use than participants with a low family income (P‐value <0.001). Participants with a higher educational level (university) had a good attitude towards rational antibiotic use than those with a lower education level (P‐value <0.001). This study has documented important knowledge and attitude gaps in antibiotic use. These findings will help health policymakers in Palestine to implement intervention programmes to rationalize antibiotic use. Continuing medical education, professional development and training workshops for healthcare professionals regarding rational use of antibiotics and health risks associated with the spread of antibiotic resistance are needed. In addition, minimizing non‐prescription use of antibiotics and increasing the public awareness about the health and economic hazards of antibiotic resistance are also required.
Age‐dependent impact of CaV3.2 T‐type calcium channel deletion on myogenic tone and flow‐mediated vasodilatation in small arteries
Authors: Mikkelsen Miriam F. , Björling Karl , Jensen Lars Jørn
Published: January 2016

Key points

Blood pressure and flow exert mechanical forces on the walls of small arteries, which are detected by the endothelial and smooth muscle cells, and lead to regulation of the diameter (basal tone) of an artery.

CaV3.2 T‐type calcium channels are expressed in the wall of small arteries, although their function remains poorly understood because of the low specificity of T‐type blockers.

We used mice deficient in CaV3.2 channels to study their role in pressure‐ and flow‐dependent tone regulation and the possible impact of ageing on this role.

In young mice, CaV3.2 channels oppose pressure‐induced vasoconstriction and participate in endothelium‐dependent, flow‐mediated dilatation. These effects were not seen in mature adult mice.

The results of the present study demonstrate an age‐dependent impact of CaV3.2 T‐type calcium channel deletion in rodents and suggest that the loss of CaV3.2 channel function leads to more constricted arteries, which is a risk factor for cardiovascular disease.

The myogenic response and flow‐mediated vasodilatation are important regulators of local blood perfusion and total peripheral resistance, and are known to entail a calcium influx into vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), respectively. CaV3.2 T‐type calcium channels are expressed in both VSMCs and ECs of small arteries. The T‐type channels are important drug targets but, as a result of the lack of specific antagonists, our understanding of the role of CaV3.2 channels in vasomotor tone at various ages is scarce. We evaluated the myogenic response, flow‐mediated vasodilatation, structural remodelling and mRNA + protein expression in small mesenteric arteries from CaV3.2 knockout (CaV3.2KO) vs. wild‐type mice at a young vs. mature adult age. In young mice only, deletion of CaV3.2 led to an enhanced myogenic response and a ∼50% reduction of flow‐mediated vasodilatation. Ni2+ had both CaV3.2‐dependent and independent effects. No changes in mRNA expression of several important K+ and Ca2+ channel genes were induced by CaV3.2KO However, the expression of the other T‐type channel isoform (CaV3.1) was reduced at the mRNA and protein level in mature adult compared to young wild‐type arteries. The results of the present study demonstrate the important roles of the CaV3.2 T‐type calcium channels in myogenic tone and flow‐mediated vasodilatation that disappear with ageing. Because increased arterial tone is a risk factor for cardiovascular disease, we conclude that CaV3.2 channels, by modulating pressure‐ and flow‐mediated vasomotor responses to prevent excess arterial tone, protect against cardiovascular disease.
Temperature Measurement Using Infrared Spectral Band Emissions From H2O
Authors: Ellis Daniel J. , Solovjov Vladimir P. , Tree Dale R.
Published: January 2016

Currently, there is no satisfactory method for measuring the temperature of the gas phase of combustion products within a solid fuel flame. The industry standard, a suction pyrometer or aspirated thermocouple, is intrusive, spatially and temporally averaging, and difficult to use. In this work, a new method utilizing the spectral emission from water vapor is investigated through modeling and experimental measurements. The method employs the collection of infrared emission from water vapor over discrete wavelength bands and then uses the ratio of those emissions to infer temperature. This method was demonstrated in the products of a 150 kWth natural gas flame along a 0.75 m line of sight, averaged over 1 min. Results from this optical method were compared to those obtained using a suction pyrometer. Data were obtained at three fuel air equivalence ratios that produced products at three temperatures. The optical measurement produced gas temperatures approximately 3–4% higher than the suction pyrometer. The uncertainty of the optical measurements is dependent on the gas temperature being ±9% at 850 K and 4% or less above 1200 K. Broadband background emission assumed to be emitted from the reactor wall was also seen by the optical measurement and had to be removed before an accurate temperature could be measured. This complicated the gas measurement but also provides the means whereby both gas and solid emission can be measured simultaneously.
Lagrangian Description Based Topology Optimization—A Revival of Shape Optimization
Authors: Zhang Weisheng , Zhang Jian , Guo Xu
Published: January 2016

Unlike in the previous treatment where shape and topology optimization were carried out essentially in an Eulerian framework, the aim of the present work is to show how to perform topology optimization based on a Lagrangian framework, which is seamlessly consistent with classical shape optimization approaches, with use of a set of moving morphable components (MMCs). It is hoped that the present work may light up the revival of classical shape optimization in structural design and optimization and inspire some subsequent works along this direction. Some representative examples are also provided to illustrate the effectiveness of the proposed solution framework.
The Control and Synchronization of a Class of Chaotic Systems With Output Variable and External Disturbance
Authors: Luo Runzi , Zeng Yanhui
Published: January 2016

This paper investigates the control and synchronization of a class of chaotic systems with external disturbance. The chaotic systems are assumed that only the output state variable is available. By using the output state variable, two types synchronization schemes, i.e., the chaos-based synchronization and the observer-based synchronization schemes, are discussed. Some novel criteria for the control and synchronization of a class of chaotic systems with external disturbance are proposed. The unified chaotic system is taken as an example to demonstrate the efficiency of the proposed approach.
Sagittal Fluoroscopy for the Assessment of Hindfoot Kinematics
Authors: McHenry Benjamin D. , Exten Emily , Long Jason T. , Harris Gerald F.
Published: January 2016

Current methods of quantifying foot kinematics during gait typically use markers placed externally on bony anatomic locations. These models are unable to analyze talocrural or subtalar motion because the talus lacks palpable landmarks to place external markers. Alternative methods of measuring these clinically relevant joint motions are invasive and have been limited to research purposes only. This study explores the use of fluoroscopy to noninvasively quantify talocrural and subtalar sagittal plane kinematics. A fluoroscopy system (FS) was designed and built to synchronize with an existing motion analysis system (MAS). Simultaneous fluoroscopic, marker motion, and ground reaction force (GRF) data were collected for five subjects to demonstrate system application. A hindfoot sagittal plane model was developed to evaluate talocrural and subtalar joint motion. Maximum talocrural plantar and dorsiflexion angles averaged among all the subjects occur at 12% and 83% of stance, respectively, with a range of motion of 20.1 deg. Maximum talocrural plantar and dorsiflexion angles averaged among all the subjects occur at toe-off and 67% of stance, respectively, with a range of motion of 8.7 deg. Based on the favorable comparison between the current fluoroscopically measured kinematics and previously reported results from alternative methods, it is concluded that fluoroscopic technology is well suited for measuring the sagittal plane hindfoot motion.
Experimental Measurement of the Static Coefficient of Friction at the Ti–Ti Taper Connection in Total Hip Arthroplasty
Authors: Bitter T. , Khan I. , Marriott T. , Schreurs B. W. , Verdonschot N. , Janssen D.
Published: January 2016

The modular taper junction in total hip replacements has been implicated as a possible source of wear. The finite-element (FE) method can be used to study the wear potential at the taper junction. For such simulations it is important to implement representative contact parameters, in order to achieve accurate results. One of the main parameters in FE simulations is the coefficient of friction. However, in current literature, there is quite a wide spread in coefficient of friction values (0.15 − 0.8), which has a significant effect on the outcome of the FE simulations. Therefore, to obtain more accurate results, one should use a coefficient of friction that is determined for the specific material couple being analyzed. In this study, the static coefficient of friction was determined for two types of titanium-on-titanium stem-adaptor couples, using actual cut-outs of the final implants, to ensure that the coefficient of friction was determined consistently for the actual implant material and surface finish characteristics. Two types of tapers were examined, Biomet type-1 and 12/14, where type-1 has a polished surface finish and the 12/14 is a microgrooved system. We found static coefficients of friction of 0.19 and 0.29 for the 12/14 and type-1 stem-adaptor couples, respectively.
Modeling and Simulation of High-Velocity Projectile Impact on Storage Tank
Authors: Kwon Y. W. , Yang K. , Adams C.
Published: January 2016

A series of numerical modeling and simulations were conducted for dynamic responses of a fluid-filled storage tank subjected to impact loading resulting from a high-velocity projectile. The focus of the study was placed on two phases. The first phase examined the structural response during the impact period without penetration while the second phase investigated the period of a projectile traveling through a fluid medium inside the storage tank. Some parametric studies were conducted to understand the dynamic responses of the structure. The parameters considered were the fluid filling level in the storage tank, fluid density, tank material properties, and projectile mass and velocity. Understanding what parameters would result in most severe damage to the structure can lead to improved design of storage tanks and proper protection against any potential incident.
The Delta Phi Method of Evaluating Overall Film Cooling Performance
Authors: Rutledge James L. , Polanka Marc D. , Bogard David G.
Published: January 2016

Film cooling designs are often evaluated experimentally and characterized in terms of their spatial distributions of adiabatic effectiveness, η, which is the nondimensionalized form of the adiabatic wall temperature, Taw. Additionally, film cooling may alter the convective heat transfer coefficient with the possibility of an increase in h that offsets the benefits of reduced Taw. It is therefore necessary to combine these two effects to give some measure of the benefit of film cooling. The most frequently used method is the net heat flux reduction (NHFR), which gives the fractional reduction in heat flux that accompanies film cooling for the hypothetical case of constant wall temperature. NHFR is imperfect in part due to the fact that this assumption does not account for the primary purpose of film cooling—to reduce the metal temperature to an acceptable level. In the present work, we present an alternative method of evaluating film cooling performance that yields the reduction in metal temperature, or in the nondimensional sense, an increase in ϕ that would be predicted with film cooling. This Δϕ approach is then applied using experimentally obtained η and h/h0 values on a simulated turbine blade leading edge region. The delta-phi approach agrees well with the legacy NHFR technique in terms of the binary question of whether the film cooling is beneficial or detrimental, but provides greater insight into the temperature reduction that a film cooling design would provide an actual turbine component. For example, instead of giving an area-averaged NHFR = 0.67 (indicating a 67% reduction in heat flux through film cooling) on the leading edge region with M = 0.5, the Δϕ approach indicates an increase in ϕ of 0.061 (or a 61 K surface temperature decrease with a notional value of T∞ −Tc = 1000 K). Alternatively, the technique may be applied to predict the maximum allowable increase in T∞ against which a film cooling scheme could protect.
Material Modeling of High-Pressure Compliant Syntactic Foams
Authors: Gruber Elliott , Cunefare Kenneth
Published: January 2016

Syntactic foam, specifically a host urethane embedded with hollow microspheres, has been shown to be an effective method to treat pressure pulsations, also known as noise, within a hydraulic system; however, the current generation of foam becomes less effective with increasing system pressure, particularly ineffective above 7 MPa. Material modeling predicts that increasing the initial internal pressure of a microsphere will allow voids within the foam to retain their size at pressures up to 35 MPa and the foam will remain compliant at those pressures. Noise is attenuated by an expansion chamber lined with syntactic foam when the system pressure causes embedded microspheres to collapse, which leaves a gaseous void within the host urethane, greatly reducing the effective bulk modulus of the foam. Predicted material properties are then used in conjunction with a previously developed linear acoustic model to predict the effectiveness of developmental syntactic foams. Changing the mechanical properties of the current host urethane does not have a drastic impact on the overall performance unless the properties have been reduced to the approximate order as the properties of the void. The factors with the most consequence on noise control effectiveness are the internal pressure of the microspheres and system pressure.
Performance Study of Vane Pump Power Split Transmission for a Highway Vehicle
Authors: Mohanty Biswaranjan , Wang Feng , Stelson Kim A.
Published: January 2016

A novel Vane Pump Power Split Transmission (VPPST), applied to a class 1 pickup truck, is demonstrated in this paper. The VPPST, a power split hydraulic transmission consists of Vane Pump Power Split Unit (VPSU) and a variable displacement hydraulic motor. The VPSU is a double acting vane pump with a floating ring. The floating ring is coupled to the output shaft, which is connected to the drive shaft. The input shaft of the VPSU is coupled to the engine. The control flow of the VPSU is fed to a variable displacement motor mounted on the VPSU output shaft. The transmission ratio is adjusted by controlling the displacement of the variable motor. The resulting continuous variable transmission allows for optimum engine operation by decoupling the engine speed from the drive speed. The transmission also has an integral clutch that allows de-clutching the engine from the drive train by retracting the vanes of the VPSU. In this paper, a quasi-static simulation approach is used to study the performance of the transmission.
Dynamical Model Research on Energy-Conversion Process of Giant Magnetstrictive Materials-Based Electrohydrostatic Actuator
Authors: Zhu Yuchuan , Yang Xulei
Published: January 2016

A giant Magnetstrictive materials-based Electro-hydrostatic Actuator (MEHA) is shown by presenting its structure configuration and working principle, which include a Giant Material Actuator (GMA), pump, two one-way check valves, a cylinder and utilize fluid rectification via one-way check valves to amplify the small, high-frequency vibrations of GMA into large motions of a hydraulic cylinder.

The established dynamic model of a MEHA involves five submodels from the viewpoint of energy conversion: the dynamic model of the power amplifier; the dynamic magnetization model that describes the relationship between the exciting current and the magnetization of the Giant Magnetostrictive Material (GMM) rod; the magnetoelastic model describing the relationship between the magnetostrictive strain and the magnetization of GMM rod; the kinetic model of the GMA describing the relationship between the GMA displacement (piston displacement of pump) and the magnetostrictive strain; the cylinder motion model.

By the simulation to the above model, dynamic characteristics of MEHA are clearly exhibited by the dynamic response curves, which show a good agreement with the experimental data and gives a scientific explanation about the test results.
Simulation-Aided Testing of Electro-Hydraulic Pump for Excavator
Authors: Cho Jaehong , Lee Jimin , Lee Jaeseok , Kim Panyoung
Published: January 2016

This paper presents a concept of pump HIL (Hardware-In the Loop) Simulation system for testing an electro-hydraulic pump of mid-class excavator. The pump HIL Simulation system integrates both the system analysis and the pump bench evaluation technique in order to enable the evaluation of the control performance of the pump during various operating condition with the entire excavator system. Hence, the analytical system model of the excavator is developed for calculating hydraulic load variation which applied to the pump during working cycle. To reflect the real dynamic characteristics of the pump, the pump in the system model is replaced with the real pump of the HIL test-bed. Moreover, linear controller is designed to test the discharge flow tracking performance of the pump and to validate the function of the HIL Simulation system. As a result, the proposed pump HIL Simulation system is verified and more effective for the advanced pump test-bed in the viewpoint of the performance evaluation.
A Survey on Negative Control Architectures for Hydraulic Excavators
Authors: Gessi Silvia , Martelli Massimo , Tonini Emanuele
Published: January 2016

The present survey is one step of a complex research activity, directed toward the conception of innovative solutions for hydraulic directional control valves for excavators of the 20-ton category.

In the world scene, as far as the hydraulic circuit present in this type of machines is concerned, a wide diffusion of the Negative Control and Positive Control architectures is observed; in literature it is also possible to find “hybrid” configurations that try to optimize system operation by taking advantage of the peculiarities of the above mentioned architectures.

Although the mechanical structure of the excavators is practically standardized among the different manufacturers, interesting solutions and configurations are adopted in the implementation of the directional control valve.

The present work aims to analyze and describe the common features observed in some of the commercial devices for the Negative Control architecture, starting from their basic structure (i.e. layout and number of sections), to get to the study of internal regenerations and external confluences (or junctions). In order to understand, in detail, the characteristics of some constructive choices (common and not, between the manufacturers), a full excavator model was implemented in the AMESim simulation environment, that includes a complex directional control valve, actuators and a 3D mechanism with 9 degrees of freedom representing the excavator’s kinematics.

By means of the simulation model, using the relevant JCMAS standards as a guideline for representative working cycles, a qualitative analysis of system operation is carried out, with a particular focus on multiple actuations (complex movements).
Energy Cost of Avoiding Pressure Oscillations in a Discrete Fluid Power Force System
Authors: Hansen Anders Hedegaard , Pedersen Henrik C.
Published: January 2016

In secondary valve controlled discrete fluid power force systems the valve opening trajectory greatly influences the pressure dynamics in the actuator chambers. For discrete fluid power systems featuring hoses of significant length pressure oscillations due to fast valve switching is well-known.

This paper builds upon theoretical findings on how shaping of the valve opening may reduce the cylinder pressure oscillations. The current paper extents the work by implementing the valve opening characteristics reducing the pressure oscillations on a full scale power take-off test-bench for wave energy converters. Further the energy losses introduced during the shifting period is investigated and compared for two valve opening algorithms. The investigation of the energy loss is utilised to quantify the importance of a fast valve switching and the energy cost of reducing pressure oscillations.

The paper will present measurements comparing pressure dynamics for two valve opening algorithms. In addition the paper will give a theoretical investigation of the energy loss during valve shifting and finally measurements of average power output from the power take-off system in various sea states are compared for the three pressure shifting times.
Modelling of Moving Coil Actuators in Fast Switching Valves Suitable for Digital Hydraulic Machines
Authors: Noergaard Christian , Roemer Daniel B. , Bech Michael M.
Published: January 2016

The efficiency of digital hydraulic machines is strongly dependent on the valve switching time. Recently, fast switching have been achieved by using a direct electromagnetic moving coil actuator as the force producing element in fast switching hydraulic valves suitable for digital hydraulic machines. Mathematical models of the valve switching, targeted for design optimisation of the moving coil actuator, are developed. A detailed analytical model is derived and presented and its accuracy is evaluated against transient electromagnetic finite element simulations. The model includes an estimation of the eddy currents generated in the actuator yoke upon current rise, as they may have significant influence on the coil current response. The analytical model facilitates fast simulation of the transient actuator response opposed to the transient electro-magnetic finite element model which is computationally expensive. Fast simulation of the problem is crucial for optimising the switching valves, especially when using several design variables in an optimisation algorithm.
Modeling of Dynamic Fluid Forces in Fast Switching Valves
Authors: Roemer Daniel B. , Johansen Per , Pedersen Henrik C. , Andersen Torben O.
Published: January 2016

Switching valves experience opposing fluid forces due to movement of the moving member itself, as the surrounding fluid volume must move to accommodate the movement. This movement-induced fluid force may be divided into three main components; the added mass term, the viscous term and the so-called history term. For general valve geometries there are no simple solution to either of these terms. During development and design of such switching valves, it is therefore, common practice to use simple models to describe the opposing fluid forces, neglecting all but the viscous term which is determined based on shearing areas and venting channels. For fast acting valves the opposing fluid force may retard the valve performance significantly, if appropriate measures are not taken during the valve design. Unsteady Computational Fluid Dynamics (CFD) simulations are available to simulate the total fluid force, but these models are computationally expensive and are not suitable for evaluating large numbers of different operation conditions or even design optimization. In the present paper, an effort is done to describe these fluid forces and their origin. An example of the total opposing fluid force is given using an analytically solvable example, showing the explicit form of the force terms and highlighting the significance of the added mass and history term in certain fast switching valve applications. A general approximate model for arbitrary valve geometries is then proposed with offset in the analytic model terms. The coefficients in this general model are determined based on CFD analyses, which are evaluated throughout the movement range of the moving member on an example valve geometry. The proposed model is compared to complete unsteady CFD simulations and found to generally predict the opposing fluid force well and gives accurate predictions under certain conditions. The proposed model is suitable for valve designers who need a computationally inexpensive fluid force model suitable for optimization routines or efficient dynamic models.
Investigation of Load Reduction Possibilities in Wind Turbines Using a Fluid Power Pitch System
Authors: Pedersen Henrik C. , Andersen Torben O. , Liniger Jesper
Published: January 2016

The pitch system is a central part of modern wind turbines and good pitch control is essential for proper operation of the wind turbine. However, often when considering the pitch control, the pitch system dynamics is approximated by a simplified low order model, which may be acceptable for electrical pitch systems and turbine control purposes, but which does not capture the potential damping possibilities that may arise by actively using the fluid power systems to reduce the loads on the wind turbine structure. The focus of the current paper is therefore on the load reduction possibilities arising from applying an active damping filter in the fluid power systems to damp structural loads on the wind turbine, while maintaining the power production.

Utilising the 5MW NREL reference wind turbine the paper presents a model of the fluid power pitch system, which is incorporated into the aeroelastic code FAST. Based on the model, an active damping approach is applied in combination with the standard pitch control to reduce oscillations in the pitch actuator force and hence the fatigue loadings on the mechanical structure. With basis in the implemented algorithm, the wind turbine is simulated under standard (IEC) load conditions and the load reduction possibilities analysed for the critical areas of the wind turbine along with performance of the wind turbine (pitch angle and power output).
Repetitive Excitation Control for Precise Measurement of Wave Propagation in Fluid Power Systems
Authors: Manhartsgruber Bernhard
Published: January 2016

Wave propagation effects in fluid power systems in general and the more specialized field of transmission line modelling have gained substantial research interest in the fluid power community. While the mathematical tools applied in computer models become more and more sophisticated, the availability of highly precise experimental data is still very limited in the fluid power literature. This paper focuses on a rather simple wave propagation experiment with a hydraulic transmission line featuring a servo-valve for excitation at one end and a blocked end boundary condition at the other end. The goal is to achieve precise control of a periodic excitation pressure waveform at the servo-valve boundary by repetitive or iterative learning control techniques. High resolution (24 bit) analog to digital conversion of the measured pressure signals together with the application of periodic averaging techniques allow for a highly precise measurement of the wave propagation dynamics including a margin of error analysis of the results. In future research, the measurement data will be used for refinement of fluid material laws for transmission line models as well as for studying the influence of geometric features like sharp edged diameter changes or elbow joints.
Stirling Power Unit: Impact of a Controlled Displacer Piston on Efficiency and Power Output
Authors: Winkelmann Anna , Barth Eric J.
Published: January 2016

This paper presents the design and dynamic model of a novel “controlled Stirling power unit” with an independently controlled displacer piston. Breaking the coupling traditionally seen in Stirling devices between the power piston and the displacer piston, realized either kinematically or dynamically, allows an additional control degree of freedom that can be used to shape the thermodynamic cycle independent of the load. The device presented combines such a controlled Stirling engine (called a pressurizer) with a power extraction unit. The dynamic models of three different power extraction units are presented. The dynamic model builds on a previous experimentally validated first-principles model of a Stirling pressurizer. The model is a lumped parameter compressible fluid power dynamic model that captures the pressure dynamics of the high pressure helium working fluid as it is affected in time by volume, mass and heat flux changes. The dynamic model of a pressurizer combined with a linear electric generator is used to study different displacer motion profiles with regard to the shape of the thermodynamic cycle, and the effect on the power output and efficiency of the device.
Testing and Modeling of a Miniature Air Compressor for a Prototype Free-Piston Engine
Authors: Johnson Dustin L. , Kittelson David B. , Durfee William K.
Published: January 2016

A miniature free-piston engine air compressor is under development as a portable compact power supply. The performance of the air compressor side of the device was measured by separating the compressor portion from the free-piston engine and bench testing it independently. The compressor was operated over a speed range of 1000 to 10,000 cycles per minute, and output mass flow of air was measured with a load pressure range of 0 to 415 kPa (0 to 60 psi) above ambient. Two thermodynamic models of the air compressor were created. The first divided the compressor cycle into four ideal gas processes. The second model simulated the cycle through many small steps, calculating the thermodynamic states iteratively using conservation of energy for an open system. Valve effects and leakage losses were included in both models. The models were validated by comparing the results with experimental data.
Experimental Validation of Mathematical Framework for Fast Switching Valves Used in Digital Hydraulic Machines
Authors: Noergaard Christian , Roemer Daniel B. , Bech Michael M. , Andersen Torben O.
Published: January 2016

A prototype of a fast switching valve designed for a digital hydraulic transmission has been manufactured and experimentally tested. The valve is an annular seat valve composed of a plunger connected with a direct electromagnetic moving coil actuator as the force producing element. Based on an elaborate optimization method the valve is designed to maximize the efficiency of a digital hydraulic motor targeted to a wind turbine transmission system. The optimisation method comprises a mathematical framework which predicts a valve switching time of approximately 1 ms with a peak actuator input power of 10 kW during switching (mean of approximately 250 W) and a pressure loss below 0.5 bar at 600 l/min. The main goal of this article is validate parts of the mathematical framework based on a series of experiments. Furthermore, this article aims to document the experience gained from the experimental work and to study and assess a moving coil actuators suitability for the application.
LES of Vaporizing Gasoline Sprays Considering Multi-Injection Averaging and Grid-Convergent Mesh Resolution
Authors: Som S. , Wang Z. , Pei Y. , Senecal P. K. , Pomraning E.
Published: January 2016

A state-of-the-art spray modeling methodology, recently presented by Senecal et al. [1,2,3], is applied to Large Eddy Simulations (LES) of vaporizing gasoline sprays. Simulations of non-combusting Spray G (gasoline fuel) from the Engine Combustion Network are performed. Adaptive mesh refinement (AMR) with cell sizes from 0.09 mm to 0.5 mm are utilized to demonstrate grid convergence of the dynamic structure LES model for the gasoline sprays. Grid settings are recommended to optimize the accuracy/runtime tradeoff for LES-based spray simulations at different injection pressure conditions typically encountered in gasoline direct injection (GDI) applications. Twenty different realizations are simulated by changing the random number seed used in the spray sub-models. It is shown that for global quantities such as spray penetration, comparing a single LES simulation to experimental data is reasonable. Through a detailed analysis using the relevance index (RI) criteria, recommendations are made regarding the minimum number of LES realizations required for accurate prediction of the gasoline sprays.
Hydrogen, Biodiesel and Ethanol for Internal Combustion Engines: A Review Paper
Authors: Taha Ahmed A. , Abdel-Salam Tarek , Vellakal Madhu
Published: January 2016

Alternative fuels research has been on going for well over many years at a number of institutions. Driven by oil price and consumption, engine emissions and climate change, along with the lack of sustainable fossil fuels, transportation sector has generated an interest in alternative, renewable sources of fuel for internal combustion engines. The focus has ranged from feed stock optimization to engine-out emissions, performance and durability. Biofuels for transportation sector, including alcohols (ethanol, methanol…etc.), biodiesel, and other liquid and gaseous fuels such as methane and hydrogen, have the potential to displace a considerable amount of petroleum-based fuels around the world. First generation biofuels are produced from sugars, starches, or vegetable oils. On the contrary, the second generation biofuels are produced from cellulosic materials, agricultural wastes, switch grasses and algae rather than sugar and starch. By not using food crops, second generation biofuel production is much more sustainable and has a lower impact on food production. Also known as advanced biofuels, the second-generation biofuels are still in the development stage. Combining higher energy yields, lower requirements for fertilizer and land, and the absence of competition with food, second generation biofuels, when available at prices equivalent to petroleum derived products, offer a truly sustainable alternative for transportation fuels. There are main four issues related to alternative fuels: production, transportation, storage, handling and usage. This paper presents a review of recent literature related to the alternative fuels usage and the impact of these fuels on fuel injection systems, and fuel atomization and sprays for both spark-ignition and compression-ignition engines. Effect of these renewable fuels on both internal flow and external flow characteristics of the fuel injector will be presented.
Heat Transfer Characteristics of Conventional and High Efficiency IC Engines Using External or Internal Exhaust Gas Dilution
Authors: Caton Jerald A.
Published: January 2016

The use of exhaust gases as a diluent for IC engine mixtures has been shown to be advantageous for lower emissions for certain operating conditions. These exhaust gases may be introduced via an external circuit (perhaps including cooling), or they may be retained (internal) in the cylinder by the use of certain valve timings. Three (3) types of dilution processes were examined in this work: external EGR, negative valve overlap, and delayed exhaust valve closing. The first process is based on external dilution, and the last two processes are based on internal dilution. Thermodynamic evaluations for an automotive engine were completed for a constant load (bmep = 900 kPa) and constant speed (2000 rpm). The thermal efficiencies decreased for all three dilution processes in similar fashion as the burned gas fraction increased. This was shown to be a result of increasing heat losses for increasing burned gas fraction. The calculations showed that even though the gas temperatures decrease with the use of exhaust gas dilution, the cylinder heat transfer actually increases. This was shown for six different heat transfer correlations typically used for these calculations. This is a result of the dependences of the convective heat transfer on cylinder gas pressure and temperature. For the cases examined, cylinder pressures increased and cylinder temperatures decreased as the dilution level increases. In all cases examined, the net result was an increase of the convective heat transfer coefficient which dominated the decrease of temperatures.
Study of Turbulent Spray Combustion of N-Dodecane Fuel
Authors: Samimi Abianeh O.
Published: January 2016

Turbulent spray combustion of n-dodecane fuel was studied numerically in current paper. The ignition delay, lift-off length, combustion chamber pressure rise, fuel penetration and vapor mass fraction were compared with experimental data. n-Dodecane kinetic model was studied by using a recently developed mechanism. The combustion chamber pressure rise was modeled and compared with experiments; the result was corrected for speed-of-sound to find the ignition delay timing in comparison with pressure-based ignition delay measurement. Species time histories and reaction paths at low and high temperature combustion are modeled and studied at two conditions, 900 K and 1200 K combustion chamber temperatures. The modeled species mass histories were discussed to define the first-stage and total ignition delay timings. Among all of the studied species in this work, including OH, Hydroperoxyalkyl mass history can be utilized to determine the exact timing of luminosity-based ignition delay. Moreover, n-dodecane vapor penetration can be used to determine the luminosity-based ignition delay.
Diagnostics of Oxygen Sensors and Air-Fuel Ratio Adaptive Controls
Authors: Jammoussi Hassene , Makki Imad
Published: January 2016

Stringent emission regulations mandated by California air regulation board (CARB) require monitoring the upstream exhaust gas oxygen (UEGO) sensor for any possible malfunction causing the vehicle emissions to exceed standard thresholds. Six faults have been identified that may potentially cause the UEGO sensor performance to deteriorate and lead to instability of the air-fuel ratio (AFR) closed-loop control system. These malfunctions are either due to an additional delay or an additional lag in the transition of the sensor response from lean to rich or rich to lean. In this paper, a novel non-intrusive approach is developed to diagnose these faults using a combination of a statistical method and a system identification process. In the second part of this work, a control strategy is presented that utilizes the type, the direction and the magnitude of the fault present to update the gains of the controller for the closed-loop air-fuel ratio control system. The proposed strategy does not require modifying the controller structure and only adapts the baseline gains of the controller and delay compensator to match the actual system dynamics (in presence of fault). The proposed approach has been demonstrated on a vehicle (Mustang V6 3.7L) where different faults were induced, and the emissions associated with each fault were measured to show the improvement.
Protect and Care (PaC) System for Lubrication Oil in Railway Applications
Authors: Fischer Götz , Schmitz Stefan
Published: January 2016

In 2006, an automatic lube oil filtration system with an automatic backflushing filter and a centrifuge for railway engines was already presented at the ASME spring technical conference in Aachen. The technical benefit of a centrifuge compared to a cartridge filter is the ability to collect smaller particles.

The power to drive the centrifuge comes from the engine oil pressure. This engine oil pressure is dependent from the engine speed. Many operating profiles of locomotives are showing low engine speed and load e.g. while waiting in switchyard and under arctic weather conditions the engines keep idling even during “downtime”. Under those conditions a centrifuge is ineffective or even out of operation.