bluuebunny/crossref_metadata_2025 huggingface dataset:
Action potential initiation in the peripheral terminals of cold‐sensitive neurones innervating the guinea‐pig cornea
Authors: Carr Richard W. , Pianova Svetlana , McKemy David D. , Brock James A.
Published: January 2009

The site at which action potentials initiate within the terminal region of unmyelinated sensory axons has not been resolved. Combining recordings of nerve terminal impulses (NTIs) and collision analysis, the site of action potential initiation in guinea‐pig corneal cold receptors was determined. For most receptors (77%), initiation mapped to a point in the time domain that was closer to the nerve terminal than to the site of electrical stimulation at the back of the eye. Guinea‐pig corneal cold receptors are Aδ‐neurones that lose their myelin sheath at the point where they enter the cornea, and therefore their axons conduct more slowly within the cornea. Allowing for this inhomogeneity in conduction speed, the resulting spatial estimates of action potential initiation sites correlated with changes in NTI shape predicted by simulation of action potentials initiating within a nerve terminal. In some receptors, more than one NTI shape was observed. Simulations of NTI shape suggest that the origin of differing NTI shapes result from action potentials initiating at different, spatially discrete, locations within the nerve terminal. Importantly, the relative incidence of NTI shapes resulting from action potential initiation close to the nerve termination increased during warming when nerve activity decreased, indicating that the favoured site of action potential initiation shifts toward the nerve terminal when it hyperpolarizes. This finding can be explained by a hyperpolarization‐induced relief of Na+ channel inactivation in the nerve terminal. The results provide direct evidence that the molecular entities responsible for stimulus transduction and action potential initiation reside in parallel with one another in the unmyelinated nerve terminals of cold receptors.
Experimentally guided modelling of dendritic excitability in rat neocortical pyramidal neurones
Authors: Keren Naomi , Bar‐Yehuda Dan , Korngreen Alon
Published: January 2009

Constructing physiologically relevant compartmental models of neurones is critical for understanding neuronal activity and function. We recently suggested that measurements from multiple locations along the soma, dendrites and axon are necessary as a data set when using a genetic optimization algorithm to constrain the parameters of a compartmental model of an entire neurone. However, recordings from L5 pyramidal neurones can routinely be performed simultaneously from only two locations. Now we show that a data set recorded from the soma and apical dendrite combined with a parameter peeling procedure is sufficient to constrain a compartmental model for the apical dendrite of L5 pyramidal neurones. The peeling procedure was tested on several compartmental models showing that it avoids local minima in parameter space. Based on the requirements of this analysis procedure, we designed and performed simultaneous whole‐cell recordings from the soma and apical dendrite of rat L5 pyramidal neurones. The data set obtained from these recordings allowed constraining a simplified compartmental model for the apical dendrite of L5 pyramidal neurones containing four voltage‐gated conductances. In agreement with experimental findings, the optimized model predicts that the conductance density gradients of voltage‐gated K+conductances taper rapidly proximal to the soma, while the density gradient of the voltage‐gated Na+conductance tapers slowly along the apical dendrite. The model reproduced the back‐propagation of the action potential and the modulation of the resting membrane potential along the apical dendrite. Furthermore, the optimized model provided a mechanistic explanation for the back‐propagation of the action potential into the apical dendrite and the generation of dendritic Na+spikes.
Synaptotagmin‐7 is a principal Ca2+ sensor for Ca2+‐induced glucagon exocytosis in pancreas
Authors: Gustavsson Natalia , Wei Shun‐Hui , Hoang Dong Nhut , Lao Ye , Zhang Quan , Radda George K. , Rorsman Patrik , Südhof Thomas C. , Han Weiping
Published: January 2009

Hormones such as glucagon are secreted by Ca2+‐induced exocytosis of large dense‐core vesicles, but the mechanisms involved have only been partially elucidated. Studies of pancreatic β‐cells secreting insulin revealed that synaptotagmin‐7 alone is not sufficient to mediate Ca2+‐dependent insulin granule exocytosis, and studies of chromaffin cells secreting neuropeptides and catecholamines showed that synaptotagmin‐1 and ‐7 collaborate as Ca2+ sensors for exocytosis, and that both are equally involved. As no other peptide secretion was analysed, it remains unclear whether synaptotagmins generally act as Ca2+ sensors in large dense‐core vesicle exocytosis in endocrine cells, and if so, whether synaptotagmin‐7 always functions with a partner in that role. In particular, far less is known about the mechanisms underlying Ca2+‐triggered glucagon release from α‐cells than insulin secretion from β‐cells, even though insulin and glucagon together regulate blood glucose levels. To address these issues, we analysed the role of synaptotagmins in Ca2+‐triggered glucagon exocytosis. Surprisingly, we find that deletion of a single synaptotagmin isoform, synaptotagmin‐7, nearly abolished Ca2+‐triggered glucagon secretion. Moreover, single‐cell capacitance measurements confirmed that pancreatic α‐cells lacking synaptotagmin‐7 exhibited little Ca2+‐induced exocytosis, whereas all other physiological and morphological parameters of the α‐cells were normal. Our data thus identify synaptotagmin‐7 as a principal Ca2+ sensor for glucagon secretion, and support the notion that synaptotagmins perform a universal but selective function as individually acting Ca2+ sensors in neurotransmitter, neuropeptide, and hormone secretion.
Divergent regulation of cardiac KCND3 potassium channel expression by the thyroid hormone receptors α1 and β1
Authors: Gassanov Natig , Er Fikret , Michels Guido , Zagidullin Naufal , Brandt Mathias C. , Hoppe Uta C.
Published: January 2009

The cardiac transient outward current Ito is regulated by thyroid hormone (T3). However, it remains unclear whether T3 directly modulates underlying gene transcription and which thyroid receptor (TR) isoform might be responsible for gene transactivation. To clarify this situation, we analysed the role of T3 and its receptors α1 (TRα1) and β1 (TRβ1) in regulation of KCNA4, KCND2, KCND3 and KCNIP2 transcription in rat cardiomyocytes. Initial results demonstrated a T3‐mediated increase of Ito current density. T3 stimulation enhanced KCND2 and KCND3 expression and decreased KCNA4 transcription, while KCNIP2 remained unaffected. To dissect the role of TRα1 and TRβ1 in T3‐dependent Ito modulation, TRα1 and TRβ1 were overexpressed in cardiomyocytes by adenovirus‐mediated gene transfer. TRα1 increased Ito, while TRβ1 significantly reduced Ito in size, which was associated with TRα1‐mediated increase and TRβ1‐mediated reduction of KCND2/3 transcription. To further evaluate a possible direct interaction of TRα1 and TRβ1 with the KCND3 promoter, TR expression vectors were cotransfected with a construct containing 2335 bp of the KCND3 5′‐flanking sequence linked to a luciferase reporter into ventricular myocytes. While the TRα1 aporeceptor enhanced KCND3 transcription, the TRβ1 aporeceptor suppressed KCND3 expression, with both effects exhibiting ligand‐dependent amplification upon T3 stimulation. Deletion of the KCND3 5′‐flanking region localized the suppressible promoter sequence for TRβ1 to within −293 bp and the activating promoter sequence for TRα1 to within −2335 to −1654 bp of the transcription start site. Disruption of putative TR binding sites by mutagenesis abolished the TRα1‐ (G‐1651T) and TRβ1‐ (G‐73T) mediated effects, indicating that TRα1 and TRβ1 response elements map to different regions of the KCND3 promoter. Thus, Ito is modulated by diverse T3‐dependent regulation of underlying gene transcription. TRα1 and TRβ1 exhibit distinct effects on KCND3 transactivation with TRα1 enhancing and TRβ1 suppressing KCND3 transcription.
A Review Paper on Aging Effects in Alloy 617 for Gen IV Nuclear Reactor Applications1
Authors: Ren Weiju , Swimdeman Robert
Published: January 2009

To understand the response of Alloy 617 to long-time exposure conditions and to determine the supplementary data needs for structural components in Gen IV nuclear reactors, literature of aging and aging effects in the alloy was reviewed. Most of the reviewed data were produced in connection with the international research effort supporting high temperature gas-cooled reactor projects in the 1970s and 1980s. Topics considered included microstructural changes, hardness, tensile properties, toughness, creep-rupture, fatigue, and crack growth. It became clear that, for the long-time very high-temperature conditions of the Gen IV reactors, a significant effort would be needed to fully understand and characterize property changes. Several topics for further research were recommended.
A Parametric Study of the Resonance Mechanism of Two Tandem Cylinders in Cross-Flow
Authors: Mohany A. , Ziada S.
Published: January 2009

A parametric study has been performed to investigate the effect of cylinder diameter on the acoustic resonance mechanism of two tandem cylinders exposed to cross-flow in a duct. Three spacing ratios corresponding to different flow regimes inside the “proximity interference” region are considered, L∕D=1.5, 1.75, and 2.5, where L is the spacing between the cylinders and D is the diameter. For each spacing ratio, six cylinder diameters in the range of D=7.6–27.5mm have been tested. For small diameter cylinders, the acoustic resonance mechanism of the tandem cylinders seems to be similar to that observed for single cylinders; i.e., it occurs near frequency coincidence as the vortex shedding frequency approaches that of an acoustic resonance mode. However, for larger diameter cylinders, the resonance of a given acoustic mode occurs over two different ranges of flow velocity. The first resonance range, the precoincidence resonance, occurs at flow velocities much lower than that of frequency coincidence. The second resonance range, the coincidence resonance, is similar to that observed for single and small diameter tandem cylinders. Interestingly, the observed precoincidence resonance phenomenon is similar to the acoustic resonance mechanism of in-line tube bundles. It is shown that increasing the diameter of the tandem cylinders affects several flow parameters such that the system becomes more susceptible to the precoincidence resonance phenomenon. The occurrence and the intensity of the precoincidence resonance are therefore strongly dependent on the diameter of the cylinders.
An Intelligent Approach to Multiple Cutters of Maximum Sizes for Three-Axis Milling of Sculptured Surface Parts
Authors: Chen Zezhong C. , Liu Gang
Published: January 2009

Due to their complex geometries, sculptured surface parts should be machined with multiple cutters of optimal sizes for high quality and productivity. Current methods of determining cutter sizes, however, are conservative and inefficient; their repeating process includes subjective cutter selection, intensive tool-path generation, and time-consuming gouging-and-interference detection in simulation. Our research proposes a new intelligent approach to multiple standard cutters of maximum sizes for three-axis sculptured surface machining. An innovative generic model of maximum allowable cutters in three-axis surface milling is built to eliminate any cutter causing local gouging and global interference. After the optimum standard cutters are automatically selected, their accessible regions can be identified, and the corresponding tool-paths can be generated, respectively. This approach is practical and effective in the process planning for three-axis milling of sculptured surface parts.
Selective Laser Sintering of Resin-Coated Sands—Part I: The Laser-Material Interaction
Authors: Quadrini Fabrizio , Santo Loredana
Published: January 2009

Selective laser sintering of precoated sands is a process utilized to produce molds and cores for rapid casting by adding sand layer by layer and heating it using a laser beam. During the process, the resin flows and binds the grains; subsequently, an oven is used for the postcuring treatment to complete the curing of the resin. The aim of this paper was to study the laser-material interaction using a diode laser to directly obtain the material consolidation. It was the first step in the definition of a new approach for process investigation and innovation. Two main aspects were investigated with the laser source in a standstill position: first, the influence of the laser power, the location of the focal spot, and the exposure time on sand consolidation; second, the shape and dimension of cured samples depending on the process parameters. The experimental data, in terms of weight and size of the hardened sands, were analyzed, and a master curve was found. In Part II of this paper the selective laser sintering process will be implemented to produce shells.
Efficient Consideration of Contact in Compliant Assembly Variation Analysis
Authors: Ungemach Georg , Mantwill Frank
Published: January 2009

The geometric deviations of real parts pose a major challenge, particularly in the extensively automated mass production of complex assemblies. To meet this challenge, an attempt is made, with the aid of statistical tolerance analysis, to predict dimensional accuracy for various assembly concepts as precisely as possible depending on the individual part tolerances. Most recent developments enable consideration to be given to the deformability of the parts during joining in order to improve the prognostic quality of simulation. The methods that are employed reveal deficits if nonlinear effects such as contact, extensive deformations, or material inelasticities occur. In this work, contact between or with adjacent parts during joining will be investigated, and an efficient and reliable method, which can be unproblematically integrated into existing compliant assembly variation analysis programs, will be developed. To achieve this, the methods of springback calculation according to Liu et al. (1995, “Variation Simulation for Deformable Sheet Metal Assemblies Using Mechanistic Models,” Trans. NAMRI/SME, 23, pp. 235–241) have been extended and coupled with numerical contact mechanics methods in order to realistically portray the problem, which usually involves intensive computing, with a minimum of additional effort. The method that has been developed will be validated on the basis of two examples with the aid of nonlinear finite element analyses, the results of which can be regarded as state-of-the-art in mechanical problems involving contact. The quality of the results reveals that this method improves the quality of prognosis for a wide range of applications and, consequently, that production problems can be combated during an early development phase.
Preferential Media for Abrasive Flow Machining
Authors: Kar Kamal K. , Ravikumar N. L. , Tailor Piyushkumar B. , Ramkumar J. , Sathiyamoorthy D.
Published: January 2009

The abrasive flow machining (AFM) is used to deburr, radius, polish and remove recast layer of components in a wide range of applications. Material is removed from the workpiece by a flowing semisolid mass across the surface to be finished. In this study a medium for AFM has been developed from the various viscoelastic carriers and has been contrasted through experimental investigation. The viscoelastic media are selected on the basis of existing media through the studies of thermogravimetric analysis and are characterized by mechanical, as well as rheological, properties with the help of a universal testing machine and a rheometer. The performance of the medium is evaluated through the finishing criteria on a two-way AFM setup. The investigation reveals that the styrene butadiene rubber (SBR) medium gives a good improvement in surface finish. The surface improvement through SBR media is 88%. It is also found that the strain, temperature, shear rate, time of applied constant stress, cyclic loading, etc. have an impact on the mechanical and rheological properties of the newly developed medium, which are ultimately governed by the performance of the medium in the target applications.
Sloshing in a Cylindrical Liquid Storage Tank With a Single-Deck Type Floating Roof Under Seismic Excitation
Authors: Matsui Tetsuya
Published: January 2009

An explicit analytical solution is derived for sloshing in a cylindrical liquid storage tank with a single-deck type floating roof under seismic excitation. The floating roof is composed of an inner deck, which may be idealized as an isotropic elastic plate with uniform thickness and mass, and connected to an outer pontoon, which can be modeled as an elastic curved beam. The contained liquid is assumed to be inviscid, incompressible, and irrotational. By expanding the response of the floating roof into free-vibration modes in air and applying the Fourier–Bessel expansion technique in cylindrical coordinates, the solution is obtained in an explicit form, which is exact within the framework of linear potential theory. Numerical results are presented to investigate the effect of the type (single-deck or double-deck) and stiffness of the floating roof on the sloshing response.
Heavy-Duty Diesel Emissions, Fifty Years: 1960–2010
Authors: Merrion David F.
Published: January 2009

Exhaust emissions from heavy-duty diesel engines have been legislated since the 1960’s and continue until 2010. Smoke emissions continue to be controlled but exhaust odor regulations were never promulgated. Gaseous emissions (oxides of nitrogen, carbon monoxide, hydrocarbons) were not regulated until 1973 and particulate matter first regulated in 1988. Emission regulations have been through several periods of cooperation between regulators and manufacturers but there have also been periods of conflict and lawsuits. The most recent issues are with the October 2002 requirements of the Consent Decrees signed by seven diesel engine manufacturers and USEPA/US DOJ/CARB. Also the 2007/2010 regulations are under review.
Design and Service Experience of the Electronically Controlled ME Engine
Authors: Knudsen Thomas S. , Groene Ole , Soerensen Per
Published: January 2009

The Norwegian shipowner Odfjell has had more than one year’s experience of operating a vessel powered by an MAN B&W 6L60MC/ME low-speed engine capable of operating by electronic valve control, without a camshaft. During that period, the engine has run in both conventional and camless modes. Valuable data has been collected on the impact of camless engine technology, on operating performance, and on operating costs. Odfjell has now ordered a 7-cylinder S50ME-C engine, featuring electronic operation, for installation on a 37,500 dwt chemical tanker newbuilding.
Characterization of Tumble Motion in SI Engines: A New Parameter
Authors: Mehta Pramod S. , Achuth M.
Published: January 2009

A well-timed turbulence due to tumble in SI engines is found to be of substantial benefit to the engine combustion process. A mean flow analysis of tumble motion in conjunction with k-ε turbulence model has been developed to provide a detailed mechanism for turbulence enhancement due to tumble. Considering that the tumble phenomenon is highly geometry dependant, an attempt is made to relate tumble-generated turbulence to the parameters relating to intake conditions and combustion chamber geometry. Finally, a new parameter ‘vortex life span’ has been proposed to characterize tumble and its turbulence, which globally encompasses intake and combustion chamber related features. The sensitivity of this parameter is demonstrated at various operating conditions. It is found that the ‘vortex life span’ has an inverse relationship with commonly measured BDC tumble ratio and is more sensitive to the chamber geometry effects.
Phenomenological Model for Swirl-Squish Interactions in Combustion Chamber Geometries of DI Diesel Engines
Authors: Sharma Rajesh , Mehta Pramod S.
Published: January 2009

The intake generated mean motion is generally augmented by the piston bowl configurations to result into desired level of fuel-air mixing in an engine combustion chamber. The swirl and squish are the two in-cylinder air motions identified in direct injection diesel engine combustion chambers. In this paper, an attempt is made to model swirl and squish interactions through a phenomenological approach considering the temporal variations of wall friction and moment of inertia of the fluids inside the piston bowl and the annular space. The model predictions are found to be in good agreement with the available experimental data.
Electromagnetic Interference (EMI) as Spark-Ignited Combustion Engines Diagnostic Parameter and Its Wireless Measurement and Wavelet Analysis
Authors: Wu Wei
Published: January 2009

This paper reveals that the ignition and combustion process of Spark-ignited Engine (SIE) inspires electromagnetic interference (EMI) that bears some inner information from SIE. The EMI conducted measurement and radiated measurement methods are experimented upon and both obtain correct signals while conducted measurement gets higher signal/noise ratio than radiated measurement. Because most signals are found in irregular structures and transient forms, the traditional frequency analysis tool Fourier Transform fails to deal with; and because during the combustion process the signals are mixed with environment noise; we use wavelet decomposition and Lipschitz signal singularity identification algorithm to confirm that among EMI signals, there are significant signals generated by SIE, thus offering an effective approach to further unveil the relationship between combustion process and EMI. Considering that the measurement is wireless completely, it is possible to develop a potable instrument for SIE diagnostic and research purpose.
Particulate Emissions From a Two-Stroke Marine Diesel Engine Operated With Heavy Fuel Oil
Authors: Tsukamoto Tatsuro , Ohe Kenji , Okada Hiroshi
Published: January 2009

In these years, a problem of air pollution in a global scale becomes a matter of great concern. In such social situation, diesel engines are strongly required to reduce the NOx and particulate emission in the exhaust gas. In this paper, measurements of particulate emissions from a low speed two-stroke marine diesel engine were conducted with several kinds of diesel oil and a heavy fuel oil, to know the characteristics of particulate emissions at the present situation. The effects of engine load and sulfur content of the fuel on the particulate emission have been examined. The particulate emission from the test engine was measured by partial-flow dilution tunnel system, and particulate matter collected on the filter was divided into four components, SOF (soluble organic fraction), sulfate, bound water and dry soot, by Soxlet extraction and ion chromatograph. Results show that the particulate emission from the test engine operated with heavy fuel oil is three times as much as the value with diesel oil and that not only sulfate but SOF and dry soot concentration increase with the increase in fuel sulfur content. It is also found that the conversion rate from sulfur in fuel into sulfate in particulate matter is nearly independent of the sulfur content in the fuel and increases with the increase in the engine load.
Development of the Tier 1 Emission Reduction Control Strategy for GE-7FDL High-Power Medium-Speed Locomotive Diesel Engine
Authors: Dillen Eric R. , Gallagher Shawn M.
Published: January 2009

This paper summarizes the technical development of the GE-7FDL series locomotive diesel engine to EPA Tier 1 emissions standards. The goal of the project was to use the existing GE-7FDL Tier 0 engine with minimal design changes and optimize for performance with respect to the Tier 1 limits. The work focused on statistically quantifying the variation seen under standard test conditions, quantifying the impact of cooling system performance, altitude, and ambient temperature on exhaust emissions and fuel consumption, and developing a robust design and control strategy to ensure optimal emissions and fuel consumption throughout the operating range and life of the locomotive. A Tier 1 prototype locomotive was used during the development to characterize the performance trends of the engine. Testing was performed over the range of altitudes required by the EPA and advanced analysis techniques were used to develop control algorithms that meet Tier 1 emissions requirements and exceed fuel consumption commitments. Extensive verification/validation testing was performed to ensure that the design goals and process capability requirements were met.
Influence of Duty Cycles and Fleet Profile on Emissions From Locomotives in Canada
Authors: Eggleton Peter , Dunn Robert
Published: January 2009

Analyses were carried out of the exhaust emissions from locomotives in Canadian railway operations based on data as of the end of 2001. The authors found that locomotive technology used in the fleet significantly influenced the emission factor while duty cycles had a lesser influence. This is because despite using less fuel for the horse-power produced, the newer diesel engines produce more emissions per unit of fuel consumed. Since 1997, there has been a significant change in the locomotive fleet profile as the Canadian Class I railways replace their 1970s’ era 3,000HP SD-40 type locomotives with modern fuel-efficient 4,300 to 6,000HP locomotives. The new locomotives being introduced, or when re-manufactured, after January 1st 2000 meet the Tier 0 emission standards of the U.S. Environmental Protection Agency. Unlike the U.S.A. where the emissions limits are the subject of legislated standards, the current Canadian situation is a voluntary one aiming to keep, country-wide, locomotive emissions of oxides of nitrogen (NOx) below a cap of 115,000 tonnes per year. The authors’ analyses provide a database upon which trends and scenarios can be examined vis-a-vis the voluntary cap set by the Railway Association of Canada for the period 1995 to 2005 in its Memorandum of Understanding with Environment Canada regarding railway locomotive emissions.
A Simplified Railway Diesel Fuel Additive Evaluation Test Protocol
Authors: Su Fan , Payne Malcolm , Vasquez Manuel
Published: January 2009

A simplified test procedure for evaluating railway diesel fuel additives at reduced cost and time relative to existing Association of American Railroads (AAR) Recommended Practice RP-503 test procedure is introduced in the paper. The emphasis is placed on critical issues considered for obtaining accurate and reliable test results during the procedure development. Results from procedure verification test are reviewed in discussions of these issues. It is pointed out that information of additives, reliable control and data recording systems, identical engine components can minimize experimental errors, and repeatability analysis of experimental measurements reveals test errors. In addition, elaborating of test methodology can eliminate systematic errors and thereby improve measurement precision. Finally, a comparison between results of an RP-503 test and a Simplified Fuel Additive Test (SFAT) using the same fuel additive product is presented.
Experiments and Modelling of Producer Gas Based Reciprocating Engines
Authors: Sridhar G. , Paul P. J. , Mukunda H. S.
Published: January 2009

A 20 kW reciprocating engine is operated using producer gas derived from a modern open top downdraft re-burn biomass gasifier that has been evaluated by rigorous laboratory performance testing over several hundred hours. The engine is operated at varying compression ratio (CR) from 11.5 to 17.0 and ignition timings from 30 to 6° before Top Centre (TC). The engine – alternator system is characterised for its performance by the simultaneous measurement of gas and airflow rates, gas composition (on-line), emission levels and power delivered. It is also instrumented to obtain the in-cylinder behaviour in the form of pressure-crank angle (p – θ) diagram to assess the thermodynamic behaviour of the engine. Three-dimensional (3-D) simulation of the flow field in the combustion chamber (involving piston-bowl arrangement) through the cycle up to the start of the combustion is used to obtain inputs on the turbulence intensity (u′) and length scale (lT) for the modelling of the flame propagation process in a zero-dimensional model (0-D) designed to predict the p – θ curve. The flame propagation and heat release processes make use of eddy entrainment and laminar burn-up model. The data on u′ extracted from the 3-D flow calculations match reasonably well with experiments till compression stroke but are in contradiction with trends close to TC. This is reasoned to be due to limitation of the k-ε model to capture transient effects due to reverse squish phenomenon. The 0-D model took into account the experimental behaviour of the u′ in the post-TC period to attempt to match the observed p – θ data over a range of CRs and ignition timing advances. While these predictions match well with the experimental data at advanced ignition timing at both higher and lower CRs, the peak pressure is under-predicted at lower ignition advances; reason are traced to increase in flame area and propagation speed due to reverse squish effect. When these are accounted in the model, the p – θ curves are predicted better.
Design and Performance of the ABB TPL65 Turbocharger With Variable Turbine Geometry for Medium-Speed Diesel Engines
Authors: Vlaskos Ioannis , Seiler Martin , Schulz Joachim
Published: January 2009

This paper presents the main features of the new ABB TPL65 turbocharger with variable turbine geometry (VTG) and highlights potential improvements in engine performance and emissions as demonstrated by measurements on a medium-speed 4-stroke diesel engine at different operational points on the propeller curve and different nozzle vane positions. Calibrated engine simulation computer models have been used to compare engine behaviour, firstly with and without the VTG-turbocharger, and secondly with alternative turbocharging systems. Test results and simulations show that ABB turbochargers with VTG enable: • Fuel economy; • A strong reduction in soot emissions; • Elimination of the thermal load problem during propeller part load operation while keeping the NOx emissions within the limits defined by the IMO regulations for medium-speed diesel engines. The results of various engine computer simulations show: • Lower fuel consumption and lower engine thermal load; • Reduced derate at high ambient temperatures; • Good engine acceleration with potentially smokeless transient engine operation.
Unsteady Flows Inside the Piping Systems of Internal Combustion Engines: 1-D Simulation Modeling and Experimental Validation
Authors: Chalet David , Chesse Pascal , Violleau Michel
Published: January 2009

The main difficulty for the one-dimensional simulation of pressure waves in the inlet and exhaust systems of Internal Combustion Engines consists in the modeling of singularities (area changes, bends, junctions, etc.). The models presented in the literature are based on the behavior of the singularity in steady flow. However the pressure losses due to the wave propagation are different from those obtained in stationary flow. The authors’ objective is to propose models with a better precision based on the non steady study of the singularities which can be found in Internal Combustion Engines. Specifically, this paper presents the investigation of the pipe wall friction factor and the sudden contraction area. The first step consists in studying the behavior of pressure waves through pipes with the Fluent CFD code. Next, a model parameterized with the Reynolds number is proposed for the pipe wall friction factor while another one with the Mach number is proposed for the sudden contraction area. These models are included in a 1-D simulation code. Finally, in order to evaluate the accuracy of the simulation program, the models are compared with experimental data. The results show a satisfactory agreement between model predictions and experimental measurements.
Use of a Micro-Contact Model to Optimize SI Engine’s 3-Piece Oil Ring Profiles Regarding Wear and Lubrication
Authors: Tomanik Eduardo , Ferrarese Andre´
Published: January 2009

A computer model that addresses the wear behavior by calculating hydrodynamic and asperity contact pressures was used to optimize the running face of three-piece oil control rings. The model incorporates Reynolds equation to calculate the oil film thickness for two sliding surfaces under a given condition (profile and topography of the surfaces, load, speed, lubricant viscosity grade and operation temperature). Prediction of the resultant asperity contact pressures is made by Greenwood-Williamson model. More scraping ring rail profiles are better for oil control, but present more wear due to higher asperity contact pressures. This higher wear can lead to less scraping profile, increasing ring end gap and lower ring tangential load, which deteriorates long term oil consumption control, hence engine durability. In the present work, a relatively simple computer program was used to predict lube oil film thickness and wear for different rail running profiles. Ring wear was assumed to be proportional to the calculated asperity contact pressure. Different rail profiles where the running profiles had a flat portion varying from less than 0.10 mm to higher than 0.20 mm were simulated and then tested in a bench test consisting in an electrical motored engine. Except for the combustion absence, all other engine characteristics were preserved (e.g., stroke, piston-ring pack, lubrication system) in the bench test. The measured oil control ring wear correlated very well with the predicted one. The model allowed the numerical optimization of the running profile of ring rail, which has lower asperity contact pressure, hence wear, but still has a good scraping capability. Two actual ICE tests were also realized. The predicted lower wear of the optimized profile was experimentally confirmed and no differences on LOC were found.
Development of a Small LIF System for Oil Film Thickness Measurements
Authors: Suguru Shinya , Masanao Shimizu , Takiguchi Masaaki , Ushijima Kenshi , Aoyama Shunichi
Published: January 2009

Laser-induced fluorescence (LIF) measurement device has been employed for measuring oil film thickness of piston and piston rings in an internal combustion engine. Reducing the size of the measurement apparatus is believed to expand the application of the LIF method. Thus, an experimental small-scale LIF measurement device has been developed. A blue laser diode was used for the light source, and a photo diode was used for the fluorescence light detection. Including such elements as lenses and optical filters, the width, length, and thickness of the device are 30, 30, and 15 mm, respectively. A drive circuit for the blue laser diode was constructed to stabilize the laser light intensity, and an amplification circuit was made for the photo diode to improve the light detection sensitivity as well as the signal frequency response. The results of the preliminary tests determined sufficient sensitivity, linearity, and frequency response required for the oil film thickness measurement. Subsequently, the device was tested on a diesel truck air compressor, and the piston ring oil film thickness was measured. The measurement results were compared with the results obtained with a conventional LIF measurement device consisting of a He-Cd laser unit and a photomultiplier. In accordance with the experimental results, the small LIF measurement device was determined to have an allowable capability for the oil film thickness measurement in an internal combustion engine.
Main Bearing Friction and Thermal Interaction During the Early Seconds of Cold Engine Operation
Authors: Shayler Paul J. , Baylis Warren S. , Murphy Michael
Published: January 2009

Motoring tests have been carried out on an unloaded crankshaft to examine the friction levels in main bearings and the influence of local thermal conditions, at speeds covering the range of 200–1000 rev/min and initial temperatures down to −20°C. The temperatures of the bearing oil film and adjacent metal are strongly coupled. This strongly influences the variation of friction during the early seconds of running. The possibility of reducing the thermal mass which acts as a heat sink for heat transferred has been examined. Heat conduction through the bearing shells can be reduced by raising the contact resistance at the back surface of the shells. Experimental data and model predictions show a significant reduction in initial friction levels can be achieved.
Finite Element Modeling of Piston-Ring Dynamics and Blowby Estimation in Single-Cylinder IC Engine
Authors: Kurbet S. N. , Krishna Kumar R.
Published: January 2009

The ring geometry, its assembly load and its mechanical and thermal properties are factors that influence engine performance. The ring dynamics is greatly influenced by piston secondary motions that depend upon the piston geometry, piston pin offset, its center of gravity (C.G.) location and piston-liner clearance. The engine is simulated to study the rings motion in axial, radial direction and the gap areas are calculated to estimate blowby and compared with experimental results. This approach to engine design reduces the conceptual design-to-development cycle time and reduces the need of extensive engine testing for evaluating ring performance.
Transient Air/Fuel Ratio Control in SI Engines
Authors: Cipollone R. , Sughayyer M.
Published: January 2009

Mixture strength control system effectiveness depends on its capacity to deal with air and fuel transport processes inside the intake manifold: the prediction of air mass flow to the engine cylinders and the compensation for the fuel lag during engine transients. These issues are all likely to be of extreme importance with the transient air/fuel ratio control strategies. This paper introduces an innovative model-based air/fuel ratio control strategy for SI engines. It is based on a previously published modeling approach for the air dynamics inside intake manifolds, which is based on the formulation of the mass, momentum and energy conservation equations and named as Method Of Interconnected Capacities. The proposed strategy uses a fuel compensator that is based on a macroscopical modeling of the fuel film dynamical behavior inside the intake manifold, which is derived from the Aquino model. A wide range of severe transient tests obtained from the experimentation of a single-cylinder research engine (type AVL 5401), equipped with port-fuel injection system, is presented. The results obtained have proved the effectiveness of the proposed strategy in controlling the air/fuel ratio in SI engines in a better way compared to the traditional control systems.
Crankcase Blowby Characterization From an EMD 16-645-E Locomotive Diesel Engine
Authors: Fritz Steven G. , Schumann Adam , Smith Brian
Published: January 2009

This paper documents results from an experimental study performed to determine the contribution of crankcase blowby to exhaust particulate matter (PM) emissions from an EMD 16-645-E, roots-blown, 1,500 kW, diesel locomotive engine. The EMD 16-645-E roots-blown engine is equipped with a closed crankcase system, where blowby is routed through an inertial separator and then into the intake air system, downstream of the intake air filters, but upstream of the roots blowers. This paper describes the system used to quantify the blowby flow rate, the blowby PM concentration (mg/m3), and the PM mass flow rate (g/hr) that is returned to the engine intake air. Since crankcase blowby is drawn from the crankcase and into the intake air due to the vacuum created by the intake air filter restriction, a series of experiments were also performed to document blowby flow rates as a function of intake air filter restriction. Blowby PM measurements were also taken upstream and downstream of the inertial separator that is used to remove some of the larger blowby aerosol particles. These data were then used to calculate the filtration efficiency of the inertial blowby separator. The crankcase blowby PM emissions are compared to the engine-out exhaust PM emissions. Results from this study indicate that for the EMD 16-645-E locomotive diesel engine tested, crankcase blowby represents less than 2 percent of the total exhaust PM emissions.
General Electric GEVO Engine for Tier 2 Locomotive Application
Authors: Flynn Paul L. , Napierkowski Susan , Hupperich Patrick , Reichert Erwin
Published: January 2009

EPA Tier 2 locomotive exhaust emission levels for U.S. locomotives present significant challenges in the reduction of NOx and particulate emissions compared to Tier 0 and 1 levels. Further tuning of legacy engines would have resulted in large losses in fuel economy to achieve NOx levels and provide for deterioration of PM, HC and smoke. For these reasons, GE Transportation Systems responded to the Tier 2 requirements with a new engine that will meet the emissions levels with margin against deterioration and with improvement in fuel consumption. This optimized balance of emissions and economy is achieved without the additional complexity of aftertreatment devices. The first engine of the GEVO family will be introduced in the Evolution Series locomotive in 2005. The performance development of the engine involved combustion modeling, system modeling and optimization. The fuel injection system was statistically designed to provide highly efficient and robust operation. The turbocharger design used advanced aerodynamic and structural modeling to achieve high levels of efficiency and safety. The reliability of each system and component was evaluated using a rigorous Design for Reliability (DFR) process followed by extensive locomotive field testing.
Mechanical Validation: An Integral Part of Medium Speed Diesel Engine Development
Authors: Lierz Klaus , Franke Michael , LeBegue Jeffrey
Published: January 2009

A comprehensive mechanical testing program was part of the development of the Diesel engine for the GEVO locomotive family. The test program has been developed under consideration of the demands of a railroad application. The program included both fired engine and component rig testing. Component rig tests were used to validate major components early in the design stage. Engine testing included measurements to validate the CAE models and allow detailed experimental development of components and subsystems. Several endurance runs have proven the reliability of the new engine.
A Study on the Numerical Prediction of Heat Release Rate and NOx Production in Medium-Speed Marine Diesel Engines
Authors: Kim Joo Youn , Yoon Wook Hyeon , Ha Ji Soo
Published: January 2009

Prediction of the ROHR (rate of heat release) and NOx production in medium-speed marine diesel engines was investigated. The subject of this paper is qualitative and quantitative evaluation of the numerical results. FIRE code v8.1 was used to examine the behavior of spray and combustion phenomena in diesel engine. Wave breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation. The spray visualization was performed experimentally in the constant-volume high-pressure chamber to clarify numerical results on the spray characteristics of the spray angle and penetration. Time-resolved spray behaviors were captured by high-speed digital camera. The simulation results were tested with the experimental data of the real engine. Finally, with adjustment of some model constants, reasonable agreements between experimental and simulated results on the ROHR and NOx were shown.
Numerical Investigations on Extended Expansion Engine
Authors: Tamilporai P. , Chandrasekaran S. , Subramaniyam S. , Jancirani J. , Lakshminarayanarao K. V.
Published: January 2009

A great deal of research has been directed towards understanding the dependence of emissions and fuel economy on the operating and design characteristics of spark-ignition homogeneous-charge engine. Several recent investigations have been concerned with modifying the conventional spark-ignition such that the part load BSFC (brake specific fuel consumption) is decreased. Many of the proposed modifications convert the engine from fixed to variable displacement, i.e., the engine size is varied to suit the vehicle needs. Another possible modification to the conventional engine is to control the load of the engine by controlling the timing of the intake-valve closure rather than by variable-density throttling. This investigation examines the delaying intake valve closing as a method of controlling the engine load without incurring the usual part-load throttling losses. The extended expansion engine (EEE) is an engine with the power output regulated by controlling the crank angle at which the intake valve closes (IVC). As in case of a conventional engine the intake valve opens just prior to and remains open through out the intake stroke of the engine. However, the intake valve also remains open over a portion of the compression stroke while the piston pushes part of the cylinder charge back into the intake manifold and stored in a plenum. A one-way valve is provided to prevent the charge from re-entering the carburetor. After the intake valve closes, the actual compression starts and the expansion and exhaust strokes are similar to those of the conventional engine. The effective cylinder volume determines the trapped cylinder charge and therefore the power output, at the time of the intake valve closing. This paper mainly deals with the numerical studies on single cylinder, four stroke, spark ignition, Extended Expansion Engine extended expansion engine with intake valve closure delayed to produce an expansion ratio that is larger than the compression ratio. The Engine processes are simulated on a computer using thermodynamic and global modeling techniques. Further the concept of lean burn technology is applied to the simulated processes and the engine performance and emission characteristics are studied from the simulated results. Two-zone combustion model is adopted for the analysis of combustion. The model is also associated with sub models for calculating the combustion duration and equilibrium composition of five product species. From this investigations and comparison of results, it is concluded that the simulation work developed predicts the performance and emission characteristics of this engine reasonably well. Therefore it is evident that the developed code can be used with confidence for further parametric studies.