bluuebunny/crossref_metadata_2025 huggingface dataset:
Double‐outlet right ventricle with intact ventricular septum
Authors: IKEMOTO YUMIKO , NOGI SHUNJI , TERAGUCHI MASAYUKI , IMAMURA HIROJI , KOBAYASHI YOHNOSUKE
Published: January 2011

An infant with double‐outlet right ventricle (DORV) with intact ventricular septum (VS) is described. Hypoplastic left ventricle and mitral valve atresia were also associated. To the authors' knowledge, this appears to be the first case in which this rare form has been demonstrated with magnetic resonance imaging (MRI). The patient required balloon atrial septostomy (BAS) three times until 4 months of age because of progressive cyanosis. In such a form of DORV, surgical atrial septectomy should be performed instead of repeating BAS because the tendency to functional closure of the restrictive secundum arterial septal defect caused by incompetent foramen ovale seems to be prominent.
Gender differences in pain modulation by a sweet stimulus in adults: A randomized study
Authors: Kakeda Takahiro , Ishikawa Toshizo
Published: January 2011

This study aimed to examine whether or not there are gender differences in sweet stimulus‐induced analgesia for cold pain in adults. In a randomized cross‐over design, twenty men and 20 women held either a 24% sucrose solution or distilled water in their mouth before and while they immersed their hand in cold water and their pain response was examined. Unlike the women, when the men held the sucrose solution in their mouth, the latency of the onset of pain significantly increased, compared with the distilled water. Meanwhile, the level of pain tolerance was not significantly different for both sexes. The findings reveal that the analgesic effect of a sweet stimulus on the pain threshold is influenced by gender differences in human adults, indicating that sweet stimulus‐induced analgesia has a brief analgesic effect, particularly for men. Although more research is warranted, the sweet stimulus could be put to practical application as an adjunct to acute pain management for men.
Establishing the Ontological Status of Thatcherism by Gauging its ‘Periodisability’: Towards a ‘Cascade Theory’ of Public Policy Radicalism
Authors: Hay Colin , Farrall Stephen
Published: January 2011

What, if anything, was Thatcherism? This article aims to gauge the extent to which it is credible and useful to speak of Thatcherism in the singular. It does so by developing a series of periodisations of the policy-making process in different policy domains since the late 1970s. This allows us to assess the degree to which a common rationale—such as might be associated with Thatcherism (as an instinct or project)—is exhibited in the sequencing of policy developments in different fields. In the process we seek to establish a new and more generally applicable methodology for establishing the existence of path-shaping political projects (such as Thatcherism) by gauging their periodisability. We conclude that the label Thatcherism is, indeed, warranted, since an account couched in such terms can illuminate an analysis of policy development since the late 1970s in a range of fields and can contribute to our understanding of the timing and sequencing of policy developments in each domain. Thatcherism, in other words, can be said to have existed because Thatcherism is periodisable. Our approach leads us to develop a ‘cascade’ theory of public policy radicalism and spillover between issue domains.
Scaling‐up Foreign Aid: Will the ‘Big Push’ Work?
Authors: Feeny Simon , McGillivray Mark
Published: January 2011

International donors are substantially scaling‐up aid programmes. At the same time, there are widespread reservations over how much aid recipient countries can use effectively. Such concerns are supported by the aid effectiveness literature which finds that there are limits to the amounts of aid recipients can efficiently absorb. This article demonstrates that a ‘big push’ in foreign aid will not lead to diminishing returns as long as donors get the inter‐country allocation of aid right. This is true even if donors provide aid at levels equal to the well‐known target of 0.7 per cent of their gross national income.
AMERICAN HISTORY IN A GLOBAL AGE1
Authors: NEEM JOHANN N.
Published: January 2011

Historians around the world have sought to move beyond national history. In doing so, they often conflate ethical and methodological arguments against national history. This essay, first, draws a clear line between the ethical and the methodological arguments concerning national history. It then offers a rationale for the continued writing of national history in general, and American history in particular, in today's global age.

The essay makes two main points. First, it argues that nationalism, and thus the national histories that sustain national identities, are vital to liberal democratic societies because they ensure the social bonds necessary to enable democratic citizens to sacrifice their immediate interests for the common good. The essay then argues that new methodological and historical work on the history of nations and nationalism has proven that nations are as real as any other historical group. Rejecting national history on critics' terms would require rejecting the history of all groups. Instead, new methods of studying nations and nationalism have reinforced rather than undermined the legitimacy of national history within the discipline.
WikiLeaks and the Perils of Extreme Glasnost
Authors: MOROZOV EVGENY
Published: January 2011

Is Internet freedom an absolute, universal value like freedom of speech? If there are limits, how and by whom can they be established? Is crying fire or scaling firewalls anymore acceptable in cyberspace than in physical space? What is the impact on the discourse between nations, cultures and individuals?

In this section, we gather a collage of comments from various key players from Google to Wikileaks to the US State Department along with comments by one of the most cogent analysts of the Net and the president of Turkey.
Atrioventricular Nodal Reentry with Retrograde Lower Common Pathway Block: A Case Report
Authors: WOOD MARK , KISER ROBERT , ELLENBOGEN KENNETH
Published: January 2011

Atrioventricular Nodal Reentry. Retrograde lower common pathway block during AV nodal reentrant tachycardia has rarely been reported. In this report, we demonstrate retrograde ventriculoatrial block during sinus rhythm and during AV nodal reentrant tachycardia in a woman with recurrent supraventricular tachycardia. In addition, evidence of antegrade decremental lower common pathway conduction is presented that produced variable HA intervals despite a constant atrial cycle length. These features may lead to the misdiagnosis of atrial tachycardia if not recognized. (J Cardiovasc Electrophysiol, Vol. 22, pp. 934‐937, August 2011)
Three Origins of Focal Atrial Tachycardia in the Lateral Mitral Isthmus
Authors: HARTONO BENY , CHANG SHIH‐LIN , LIN YENN‐JIANG , CHEN SHIH‐ANN
Published: January 2011

Three Origins of Focal Atrial Tachycardia. Multiple origins of focal atrial tachycardia (AT) located at the left lateral isthmus is a rare case. We present a case of a 31‐year‐old female with incessant AT. During radiofrequency ablation, 3 origins of AT located in the lateral mitral ishtmus from a lower to a higher position were identified with changes of the ECG morphology and earliest activation on 3D mapping. Ablation of the AT origins can terminate the tachycardia. (J Cardiovasc Electrophysiol, Vol. 22, pp. 931‐933, August 2011)
miR‐181 as a putative biomarker for lymph‐node metastasis of oral squamous cell carcinoma
Authors: Yang Cheng‐Chieh , Hung Pei‐Shih , Wang Pei‐Wen , Liu Chung‐Ji , Chu Ting‐Hui , Cheng Hui‐Wen , Lin Shu‐Chun
Published: January 2011

J Oral Pathol Med (2011) 40: 397–404

Background:  Oral squamous cell carcinoma (OSCC) is an important malignant disease around the world. Aberrant expression of MicroRNAs (miRNAs) has been implicated in carcinogenesis of various cancers. In previous studies, up‐regulation of miR‐181 was observed when OSCC progressed from leukoplakia, dysplasia to invasive carcinoma. However, the function of miR‐181 in oral tumorigenesis remains unclear.

Materials and methods:  The expression levels of miR‐181 in the tissue and plasma of OSCC patients were measured by quantitative RT‐PCR. The correlation between miR‐181 level and multiple clinical variables were then checked by Mann–Whitney test and Wilcoxon matched pairs test. To study the functional meaning of up‐regulated miR‐181, migration assay and invasion assay by transwells and colony forming assay were applied to analyze the tumorigenic phenotypes of OSCC cells with ectopical expression of miR‐181.

Results:  Among different clinical variables, over‐expression of miR‐181 was correlated with lymph‐node metastasis, vascular invasion, and a poor survival. Functional assays revealed ectopically over‐expressed miR‐181 would enhance cell migration and invasion, but not the ability of anchorage‐independent growth of OSCC cells. In addition, the up‐regulation of miR‐181 could be detected both in tumor tissues and plasma.

Conclusion:  miR‐181 may enhance lymph‐node metastasis through regulating migration, which could potentially be exploited as a putative biomarker for patients with OSCC.
Study on the Relationship Between Different Cytokines in the Semen of Infertility Patients
Authors: Qian Li , Sun Gang , Zhou Baocheng , Wang Gang , Song Jicheng , He HaoMing
Published: January 2011

Citation Qian L, Sun G, Zhou B, Wang G, Song J, He HM. Study on the relationship between different cytokines in the semen of infertility patients. Am J Reprod Immunol 2011; 66: 157–161

Problem The relationship between different cytokines in the semen of infertility patients was investigated.

Method of study Fifty‐seven semen samples were collected from infertility and normal group at Lianyungang Maternal and Child Hospital. Routine analysis including determination of the levels of IL‐23, IL‐6, and TNF‐α was carried out.

Results Density, percentage of sperm moving forward, activity, survival rate, and proportion of normal morphology of sperm of normal group were significantly higher than those of infertility group (P < 0.001). Amount and pH of the semen from the two groups showed no difference. However, there is a significant difference in IL‐23 contents of semen in the normal (5.87 pg/mL) and abnormal (11.14 pg/mL) group (P < 0.001). The correlation coefficients (R) of the contents of IL‐23 to IL‐6, IL‐8, and TNF‐α were 0.8706 (R2 = 0.758,P < 0.001), 0.9725 (R2 = 0.9458,P < 0.001), and 0.9499 (R2 = 0.9024,P < 0.001), respectively.

Conclusion IL‐23 contents of semen are different in the normal and abnormal group and have positive correlations between IL‐6, IL‐8, and TNF‐α, respectively.
Serum concentrations of Anti‐Müllerian Hormone (AMH) in 95 patients with Klinefelter syndrome with or without cryptorchidism
Authors: Aksglaede Lise , Christiansen Peter , Sørensen Kaspar , Boas Malene , Linneberg Allan , Main Katharina M , Andersson Anna‐Maria , Skakkebæk Niels E , Juul Anders
Published: January 2011

Aim:  Anti‐Müllerian hormone (AMH) is produced by foetal Sertoli cells at the time of sexual differentiation and is responsible for the regression of the Müllerian ducts in the male foetus. AMH is a testis‐specific marker of diagnostic value in infants with ambiguous genitalia or with bilateral cryptorchidism. However, little is known about AMH in boys and adult men with normal or abnormal gonadal function. We therefore aimed at determining circulating AMH concentrations in patients with 47,XXY Klinefelter syndrome (KS) with or without cryptorchidism.

Methods:  AMH was determined in 95 47,XXY patients aged 0.2–64.5 years, of which 12 patients had a history of cryptorchidism.

Results:  AMH was within the normal range in boys with Klinefelter syndrome until puberty. The pubertal decline was delayed, especially in patients with a history of cryptorchidism. AMH was below −2 SD in 85% of adult KS.

Conclusion:  AMH secretion in patients with 47,XXY KS was within normal limits during mini‐puberty and until puberty. Thereafter, AMH declined to subnormal levels in all patients. We hypothesize that this decline was a result of the hyalinization of seminiferous tubules in relation to puberty, rather than caused by disrupted regulatory mechanisms at the level of the pituitary–gonadal axis.
THE EDUCATIONAL MEANING OF COMMUNAL LAUGHTER: ON THE EXPERIENCE OF CORPOREAL DEMOCRACY
Authors: Vlieghe Joris , Simons Maarten , Masschelein Jan
Published: January 2011

In this article Joris Vlieghe, Maarten Simons, and Jan Masschelein attempt to articulate a new way of dealing with the public character of education. Instead of discussing laughter as an instrument that one could use to facilitate established educational goals, the authors provide an extensive analysis of the phenomenon of laughter as a specific form of corporeal behavior. Their analysis demonstrates that when we laugh, we give an answer to a disorienting situation, but this answer is not the product of intentional agency. Instead, it consists in the uncontrollable spasmodic contraction of our diaphragm and other impersonal and automatic corporeal reactions. We are thus exposed to an ultimate loss of self‐control. The authors argue further that communal laughter—that is, when the lack of mastery over our own lives becomes a shared experience—results in what they call a “democracy of the flesh.” In this state, it is no longer possible to stick to well‐defined positions, nor is it tenable to defend any hierarchical ordering, including the strict hierarchy we typically find in the context of schooling and education. Common laughter makes equals out of us and grants the possibility of an unforeseen and unimaginable future. For precisely this reason, the authors conclude, communal laughter might be considered as an educational event itself.
EMPIRICAL ANALYSIS OF REFERRAL ISSUES AND “ULTIMATE ISSUE” RECOMMENDATIONS FOR PARENTS IN CHILD PROTECTION CASES*
Authors: Budd Karen S. , Springman Rachael E.
Published: January 2011

Mental health professionals frequently respond to requests for clinical information on parents in child protection cases; however, little data exist on the issues precipitating requests or on the controversial practice of offering “ultimate issue” recommendations in forensic clinical reports. We investigated 243 requests for clinical information on parents and 204 clinician reports submitted for use in child abuse and neglect proceedings in a large, urban juvenile court system. We coded 56 objective and qualitative characteristics regarding referral questions, pending legal issues, and four levels of recommendations. We found that the most common referral questions related to service planning, parenting ability, and/or parents' mental health functioning, and the most common pending legal issues were selection or change of a permanency goal and visitation arrangements. Levels of recommendations varied with type of legal decision, in that clinicians always offered direct recommendations for narrow, statute‐based issues (e.g., termination of rights, adoption) and less so for other issues. Community‐based evaluators were more likely to offer direct recommendations than court‐based clinicians. Based on the findings, we offer practice recommendations and directions for further research in forensic parenting assessment.
A MODIFIED DNA EXTRACTION MINIPREPARATION PROTOCOL FOR FUSARIUM ISOLATES
Authors: ABD‐ELSALAM KAMEL A. , SCHNIEDER FRANK , GUO JIAN‐RONG
Published: January 2011

Abstract  We have modified a quick, inexpensive and less prone to contamination protocol by culturing the cryopreserved or fresh mycelium directly in 96‐deepwell plate. The method facilitates concomitant assessment of ssDNA fungal diversity by asymmetric PCR (A‐PCR) from a single extraction. The DNA yields from Fusarium spp. isolates was reasonably high, and a clear DNA band was frequently seen when 10 μL of the PCR product was run in agarose gel. The procedure can be completed in less than 4 h and 96 samples can be processed at the same time.
Forced Convection in a Polygonal Duct With a Circular Core
Authors: Wang C. Y.
Published: January 2011

The H1 forced convection through a regular polygonal duct with a centered core is studied using eigenfunction expansions and point match. Accurate Nusselt numbers for the full range of core radii are presented.
Development of Low NOx Capability on the Dresser Waukesha 275GL Series Engines
Authors: Sorge Gregory W. , von der Ehe James K.
Published: January 2011

Dresser Waukesha’s 275GL engine family released in 2009 consists of a 214 liter (13,048 in3) 12 cylinder, and a 285 liter (17,398 in3) 16 cylinder engine derived from Waukesha’s ATGL family. These 1000 RPM engines are typically used in mechanical drive applications for natural gas compression at 2500 to 3300 kWb (3400–4500 bhp). Through market analysis and voice of customer (VOC) interviews, it was determined that lower Oxides of Nitrogen (NOx) output is essential for future engine sales in North America. Meeting this requirement with a minimal impact to fuel efficiency, fuel tolerance, turndown range, and altitude capability were also desired. To meet the lower NOx requirement, combustion was improved using Computational Fluid Dynamics (CFD) modeling and Design of Experiments (DoE) tools. To assure the low NOx emissions were maintained throughout the desired operating regime, an NOx sensor based air/fuel ratio control system was developed. This new NOx control capability is an enhancement to the Dresser Waukesha ESM™ engine control system. The result is an engine family that consistently meets stringent 0.5 g/bhp-hr NOx levels while maintaining fuel efficiency, fuel tolerance, and turndown range. Reduced combustion pressure in the 275GL Low NOx engine has also allowed a power increase over the original 275GL engine. This paper will discuss the testing and results of this development.
End-of-Injection Behavior of Diesel Sprays Measured With X-Ray Radiography
Authors: Kastengren Alan , Powell Christopher F. , Liu Zunping , Moon Seoksu , Gao Jian , Zhang Xusheng , Wang Jin
Published: January 2011

The behavior of diesel fuel sprays at the end of injection is poorly understood, yet has important implications regarding diesel engine emissions. Recent research has shown that at the end of injection, an entrainment wave is created, causing the fuel spray to rapidly entrain ambient gas. This rapid entrainment creates a dilute mixture of fuel that may be a source of unburned fuel emissions. In this study, x-ray radiography is used to examine the end-of-injection behavior of diesel sprays. X-ray radiography permits quantitative mass distribution measurements in dense sprays, providing data that cannot be obtained with optical techniques. Analysis of the spray velocity at steady-state suggests an entrainment wave speed of several hundred m/s, which is supported by the appearance of a travelling entrainment wave at low ambient density. The spray density declines most rapidly near the nozzle, behavior that matches the expected entrainment wave behavior. In several cases, the spray distribution in a cross-section across the nozzle axis becomes smoother at the end of injection. Three-dimensional reconstructions of the spray density at the end of injection show that the spray plume widens considerably, enhancing the dilution caused by the reduction in spray mass in the flowfield. Measurements of injector needle motion with x-ray phase contrast imaging show that throttling across the needle seat may cause a smearing of the ideally sharp entrainment wave.
A Comparative Study of Combustion Models for Spark Ignition Engines Based on Experimentation and CFD Simulation
Authors: Mobasheri Raouf , Shahrokhi-Dehkordi M. Sadegh
Published: January 2011

Computational fluid dynamics (CFD) is able to significantly reduce the number of experimental tests and measurements and lower the development time and costs. However some parameters which are needed for CFD calculation must be achieved experimentally. In this paper, a comparative study was carried out to clarify the effect of three different combustion models on the prediction capability of combustion process and NOx emission on a modified 4-cylinder MPFI SI engine. Validation of the combustion model has been performed through comparing simulation data with the experimental results and a satisfactory agreement between them has been achieved in terms of combustion parameters and NOx emission. The results show that, applying appropriate constants of each combustion model including Eddy break up model (Ebu), Probability density function (Pdf) and Coherent flamelet model (Cfm) causes the computational results to be in agreement with experimental results. Furthermore the results show that the nearest prediction in comparison with experimental results is by applying the Ebu model.
The Destruction of Exergy During the Combustion Process for a Spark-Ignition Engine
Authors: Caton Jerald A.
Published: January 2011

The second law of thermodynamics provides the mechanism for assessing the quality of energy. The non-conserved property used for this assessment is called exergy, availability or available energy. For the internal combustion engine, the exergy of the fuel is distributed among work, heat transfer, exhaust, and is destroyed by several processes. The major destruction of exergy for the internal combustion engine is during the combustion process. This paper documents this destruction for a wide range of engine operating parameters, design parameters, and fuels. A 5.7 liter, spark ignition, automotive engine was selected for this study. Operating parameters that were examined included equivalence ratio, speed, load and spark timing. Design parameters that were examined included compression ratio, expansion ratio and the use of turbocharging. Combustion parameters and oxidizer were examined as well. The fuels examined included isooctane (base), methane, propane, hexane, methanol, ethanol, hydrogen and carbon monoxide. For the part load base case (1400 rpm and a bmep of 325 kPa) using isooctane, the destruction of exergy was 21% of the fuel exergy. For many of the engine operating and design parameters, this destruction was relatively constant (between about 20 and 23%). The parameters that resulted in the greatest change of the exergy destruction were (1) exhaust gas recirculation, and (2) inlet oxygen concentration. In general, the amount of the destruction of exergy during the combustion processes was associated with the level of the combustion temperatures.
Comparison of Regulated and Unregulated Exhaust Emissions From a Fleet of Multi-Fuel Solid Resource Collection Vehicles
Authors: Thiruvengadam Arvind , Carder Daniel K. , Krishnamurthy Mohan , Gautam Mridul
Published: January 2011

The refuse truck segment of the heavy duty diesel vehicle population has been identified as the most fuel inefficient sector. This is predominantly due to the stop and go driving pattern associated with these trucks. Constantly evolving emissions norms are forcing large truck fleet operators to explore the economic viability of alternative fueled vehicles to combat the increasing operating costs in terms of retrofit requirements of heavy-duty diesel vehicles. The objective of this study was to determine the emissions benefits and the economic viability of introducing liquefied natural gas (LNG), and LNG-Ultra-low sulfur diesel (ULSD) dual-fueled vehicles into the solid resource collection vehicle fleet (SRCV) in the city of Los Angeles. The 12 vehicles tested in this study were part of a multi-fuel refuse truck fleet. It should be noted that these vehicles are not representative of the state-of-the-art advanced technology engines that power the present day fleets. Vehicles were exercised over the AQMD refuse truck cycle and a newly developed compaction cycle on a heavy-duty chassis dynamometer. Regulated emissions together with a whole spectrum of unregulated speciation including the analysis of 1,3 butadiene with an on-site gas chromatograph was performed. Results showed that PM distance-specific mass emissions from LNG-fueled vehicles were on an average 82% lower than diesel trucks equipped with a DPF. Chemical speciation of exhaust from different fueled trucks indicated a characteristic emissions profile specific to the fuel used in these vehicles. While emissions from LNG vehicles were characterized by carbonyls, and other lower chain hydrocarbon compounds, emissions from diesel vehicles were dominated by polyaromatic hydrocarbons (PAH) and higher chain hydrocarbons.
Modeling Species Inhibition of NO Oxidation in Urea-SCR Catalysts for Diesel Engine NOx Control
Authors: Devarakonda Maruthi , Tonkyn Russell , Tran Diana , Lee Jong , Herling Darrell
Published: January 2011

Urea-selective catalytic reduction (SCR) catalysts are regarded as the leading NOx aftertreatment technology to meet the 2010 NOx emission standards for on-highway vehicles running on heavy-duty diesel engines. However, issues such as low NOx conversion at low temperature conditions still exist due to various factors, including incomplete urea thermolysis, inhibition of SCR reactions by hydrocarbons and H2O. We have observed a noticeable reduction in the standard SCR reaction efficiency at low temperature with increasing water content. We observed a similar effect when hydrocarbons are present in the stream. This effect is absent under fast SCR conditions where NO ∼ NO2 in the feed gas. As a first step in understanding the effects of such inhibition on SCR reaction steps, kinetic models that predict the inhibition behavior of H2O and hydrocarbons on NO oxidation are presented in the paper. A one-dimensional SCR model was developed based on conservation of species equations and was coded as a C-language S-function and implemented in Matlab/Simulink environment. NO oxidation and NO2 dissociation kinetics were defined as a function of the respective adsorbate’s storage in the SCR catalyst. The corresponding kinetic models were then validated on temperature ramp tests that showed good match with the test data.
Particulate Matter Emissions From a High-Emitting Diesel Vehicle Measured With an On-Board Electronic PM Sensor
Authors: Osara Jude A. , Diller Timothy T. , Hall Matthew J. , Matthews Ronald D. , Heinrich Jakob
Published: January 2011

Measurements of time-resolved particulate matter emissions from a high-emitting light-duty diesel vehicle were made using an electronic particulate matter sensor developed at the University of Texas. The sensor, which is threaded directly through the exhaust pipe wall, detects the time-resolved mass concentration of carbonaceous PM in undiluted vehicle exhaust. The sensor works by detecting an electrical current that is created between two electrodes that have a large potential difference across them; a current is created when particles are present. The sensor was used to characterize the PM emissions from a Chevrolet Equinox SUV which had its original gasoline engine replaced with a 1.9 liter Fiat/Opel turbo-diesel. The vehicle was without a diesel particulate filter (DPF) and had transient PM emission concentrations during accelerations as high as 1000 g/m3. The sensor’s output closely followed exhaust opacity. PM emissions were found to be highest for rapid accelerations and were strongly correlated with pedal position, which can be taken as a surrogate for the fuel delivery per cycle. The sensor was calibrated against gravimetric filter measurements of dry PM mass captured from the vehicle’s exhaust in sample bags.
Modeling the Effect of Nozzle Hole Geometry on Diesel Injection and Combustion
Authors: Chiatti G. , Chiavola O. , Palmieri F.
Published: January 2011

The performance of the ensemble diesel engine-injection system has been investigated by modeling; different approaches have been combined and integrated in a multi step procedure. In a preliminary phase, the nozzle flow features have been investigated by means of 3D CFD simulation (FIRE), allowing for the evaluation of nozzle hole discharge coefficients. Such values have been used in the subsequent phase, based on a 0/1D approach, in which the complete model of the fuel injection system has been realized and the injected fuel amounts have been evaluated. On the basis of these indications, a further simulation phase has been included and a packet model for the modeling of fuel jet formation, evaporation and combustion has been built and used. In-cylinder pressure trends have been obtained and the effects of different nozzle hole geometries have been investigated.
Experimental Study of Turbocharger’s Performances at Low Speeds
Authors: Deligant Michael , Podevin Pierre , Descombes Georges , Lamquin Thierry , Vidal Fabrice , Marchal Alexandre
Published: January 2011

One of the most efficient ways to reduce the pollution and fuel consumption of an automotive engine is to downsize the engine, whilst maintaining a high level of power and torque. This is achieved by using turbochargers. In urban, and often in suburban, traffic conditions the engine power demand is weak in relation to the maximum power available, so the turbocharger runs at low speed. To appreciate and improve engine performance, it is necessary to know the characteristics of the turbomachinery in this functioning area, characteristics which are not given by turbocharger manufacturer. The reason for this lack of information will be explained and the experiments we are currently conducting at low turbocharger speed are presented. Experimentally, it has been demonstrated that the measured performances of the compressor are dependent on heat exchange (convection and conduction) and are also linked to the pressure and temperature of the lubricating oil. At the CNAM laboratory, the turbocharger test rig has been equipped with a special torquemeter, allowing rotation speeds of up to 120000 rpm, set up between the turbine and the compressor. The turbine is thus separated from the compressor and could be considered as a drive which provides mechanical power to the turbocharger (torquemeter + compressor + bearing unit). Temperature and pressure of the lubricating oil can be adjusted to an experiment’s requirements. The test bench lay out is described. To achieve accurate measurements and evaluate the influence of heat exchanges, tests have been carried out with the whole compressor thermally isolated and with preheated inlet air. The compressor can be assumed to be adiabatic, and the power given to the air flow can be calculated using the first law of thermodynamics. Mechanical bearing losses can be deduced from this calculation and torquemeter power, but also from measurements of lubricating oil flow, and oil temperature at inlet and outlet. The results of experiments for different lubricating oil temperatures and pressures and turbocharger speeds are presented. Real compressor characteristics curves are set up and a comparison of experimental mechanical power losses with a journal bearing CFD model is presented.
In-Cylinder Equivalence Ratio Measurements in a EGR Equipped Engine
Authors: Gupta Sreenath B. , Bihari Bipin , Biruduganti Munidhar , Sekar Raj
Published: January 2011

A single-cylinder natural gas fueled engine equipped with a Exhaust Gas Recirculation (EGR) system was ignited using a laser. The broadband emission from the spark kernel was spectrally resolved and the peaks corresponding to Hα, N and O atoms were measured for a range of conditions with global equivalence ratios ranging between 0.6 and 1.0, and for Exhaust Gas Recirculation fractions up to 29%. The (Hα/O) and (Hα/N) peak intensity ratios from the spectral scans correlated extremely well (R2 > 0.97) with local oxygen based equivalence ratios. Appropriate relations were developed to relate such values to global equivalence ratios and the EGR rate. For homogenous intake charge, the present LIBS diagnostic enables estimation of one of the two values, global equivalence ratio or EGR rate, with the knowledge of the other.
Effects of Thermal Cycling on Elastomers in High Temperature Coolant
Authors: Hertz Daniel L.
Published: January 2011

In the past ten years diesel engine performance has significantly increased in terms of kilowatts/litre (kW/L). These higher power density outputs create higher thermal loads on the cooling system and associated seals. While compatibility of elastomers in high temperature coolants has been studied and reported, the inevitable impact of thermal cycling on these elastomers is not well documented. This study examines the effects of thermal cycling in three general coolant categories on three different elastomers commonly considered for sealing hot engine coolants. The elastomers, by ASTM D1418 designation, are HNBR, FKM Type 2, and FEPM. The coolants are an organic acid technology (OAT) coolant, a propylene glycol premix coolant, and a corrosion inhibited de-ionized water. Normal service applications are characterized by an indefinite number of shutdowns and startups. Testing was designed to simulate such service. Aging periods incorporated ongoing 24 hour cycles: a 16 hour period to heat up and operate at 150°C, and an 8 hour period to cool off to ambient. O-rings, a common seal design, were subject to axial and radial deformation during testing. The o-rings’ sealing attributes were examined after four, ten, twenty, and forty cycles. Elastomeric properties were evaluated, before and after cyclical aging, in accordance with ASTM D1414-94 (“Standard Test Methods for Rubber O-rings”) and D412-06a (“Standard Test Methods for Vulcanized Rubber … - Tension”). Compressive stress relaxation (CSR) was evaluated using an in-house procedure, comporting with ASTM D6147-94.
CFD and Optical Investigations of Fluid Dynamics and Mixture Formation in a DI-H2ICE
Authors: Scarcelli Riccardo , Wallner Thomas , Obermair Hermann , Salazar Victor M. , Kaiser Sebastian A.
Published: January 2011

This paper reports the validation of a three-dimensional numerical simulation of the in-cylinder processes during gas-exchange, injection, and compression in a direct-injection, hydrogen-fueled internal combustion engine. Computational results from the commercial code Fluent are compared to experimental data acquired by laser-based measurements in a corresponding optically accessible engine. The simulation includes the intake-port geometry as well as the injection event with its supersonic hydrogen jet. The cylinder geometry is typical of passenger-car sized spark-ignited engines. Gaseous hydrogen is injected from a high-pressure injector with a single-hole nozzle. Numerically and experimentally determined flow fields in the vertical, central symmetry plane are compared for a series of crank angles during the compression stroke, with and without fuel injection. With hydrogen injection, the fuel mole-fraction in the same data plane is included in the comparison as well. The results show that the simulation predicts the flow field without injection reasonably well, with increasing numerical-experimental disagreement towards the end of the compression stroke. The injection event completely disrupts the intake-induced flow, and the simulation predicts the post-injection velocity fields much better than the flow without injection at the same crank-angles. The two-dimensional tumble ratio is evaluated to quantify the coherent barrel motion of the charge. Without fuel injection, the simulation significantly over-predicts tumble during most of the compression stroke, but with injection, the numerical and experimental tumble ratio track each other closely. The evolution of hydrogen mole-fraction during the compression stroke shows conflicting trends. Jet penetration and jet-wall interaction are well captured, while fuel dispersion appears under-predicted. Possible causes of this latter discrepancy are discussed.
Comparison of Crankangle Based Ignition Timing Methods on an HCCI Engine
Authors: Ghazimirsaied Ahmad , Shahbakhti Mahdi , Koch Charles Robert
Published: January 2011

Autoignition timing of a mixture in Homogeneous Charge Compression Ignition (HCCI) is very dependant and sensitive to the engine operating condition. To characterize combustion timing, different crank angle dependant methods are used but these methods can exhibit inaccurate results at some operating conditions. In this paper, a criterion that divides the engine operating condition into two regions, low and high cyclic variations (unstable operation) is defined. Then, different crankangle based methods for determining the start of combustion inside the cylinder for each of the two regions are compared. The start and duration of combustion are compared for wide range of operating conditions and the relative merits of each method discussed. The methods for characterizing the start of combustion are: CA50 based on the total heat release; the start of combustion from the third derivative of the pressure trace with respect to crank angle; the start of combustion from the third derivative of the pressure trace with respect to crank angle with two limits; CA10 based on total heat release; CA10 based on peak of main stage of combustion. The last method is introduced in this paper and has advantages in terms of accuracy of ignition timing detection and correlation with the start of combustion particularly for high cyclic variation engine operation. A new criterion, defined as the ratio between peak of main stage and the sum of peak of main stage and cool flame stage of heat release, is introduced to more accurately identify the operating region of the engine. This criterion is used to understand the performance of each of those crank angle based methods. The performance of each of those methods is investigated for both the low cyclic variation and the high cyclic variation (unstable) region of the engine.
Investigation of Ethanol Spray From Different DI Injectors by Using Two-Dimensional Laser Induced Exciplex Fluorescence at Potential Cold-Start Condition
Authors: Chen Hao , Xu Min , Zhang Gaoming , Zhang Ming , Zhang Yuyin
Published: January 2011

The spray evaporation of gasoline and ethanol fuel was investigated qualitatively through the use of the planar laser induced exciplex fluorescence (PLIEF) technique in a constant volume chamber. The effect of fuel temperature and ambient pressure on spray evaporation was identified over a range of conditions. Both a swirl injector and a multi-hole injector were examined for each of the two fuels. A coevaporative mixture of benzene and triethylamine (TEA) was used as a fluorescent seeding material to study the evaporation processes of ethanol fuel. A mixture of fluorobenzene (FB) and diethylmethylamine (DEMA) in n-hexane, which has been proved to be a suitable seeding material for LIEF measurement, allowed for the investigation of the evaporation processes of gasoline fuel mixture. Remarkable spray evaporation processes were observed for both gasoline and ethanol fuel by increasing fuel temperature or by reducing ambient pressure to a vacuum. Especially after achieving flash-boiling, the vapor distribution of multi-plume spray increases dramatically, and the vapor phase of spray from swirl injector gathers to the centerline of injector by increasing the superheated degree. The collapsing of both liquid and vapor phases of n-hexane is stronger than that of ethanol spray for both swirl and multi-hole injectors.
Mixture Quality Evaluation for Transient Mode Gasoline Engine Calibration
Authors: Fuchs Heribert , Hirsch Alois , Ogris Martin , Winklhofer Ernst
Published: January 2011

Gasoline engines have perfect emissions quality in stationary part load operation — how to ensure such ideal operation also at engine start, at tip-in tip-out, and at full load conditions? Key to the solution of these issues is the optimum use of components for mixture formation, combustion and exhaust gas aftertreatment with the focus on actuator calibration yielding reliable and low emissions combustion under transient operating conditions. Conventional testing of actuator parameter settings for such transients is evaluated with engine out emissions measurements. Any emissions peaks are well understood to be the result of some specific cycles which suffer from inadequate mixture formation due to limitations of fuel injection, evaporation or air supply. Consequently, improvements are achieved with adaptation of actuator parameters such as fuel injection timing, multiple injections or throttle and boost pressure settings in part load operation. With in-cylinder events being the root cause for emissions related issues, there is demand for diagnostic techniques capable of identifying emissions relevant in-cylinder processes for individual cylinders and on a cycle by cycle basis. This demand is met with the measurement of in-cylinder pressure together with flame radiation intensity. As cylinder pressure signals are evaluated for combustion stability, the simultaneously recorded flame signals provide information on mixture preparation quality. Well premixed charge results in flame radiation signals which are typical for homogeneous turbulent flames. Insufficiently evaporated and partially mixed fuel, especially at engine start, yields flame signals typical for diffusion flames. This simple relation between flame signals and soot formation events provides the basis for measurement techniques enabling mixture formation evaluation for individual cylinders and individual cycles. The application of such in-cylinder pressure and flame measurement techniques to PFI and GDI engines is presented with examples for engine cold start testing. The technique is further applied in the calibration of engine tip-in transients.
In-Cycle Closed Loop Control of the Fuel Injection on a 1-Cylinder Heavy Duty CI-Engine
Authors: Zander Claes-Go¨ran , Tunesta˚l Per , Stenla˚a˚s Ola , Johansson Bengt
Published: January 2011

The focus of this article is on implementation of real time combustion control by using an FPGA. The feedback used for the controller is the heat release. Due to the desire to avoid using division on the FPGA an alternative way of calculating the polytropic exponent is investigated. When this method is compared against using a constant exponent it shows less fluctuations in regards to cycle to cycle variations when calculating the heat release. A dual injection strategy is used and real time control is implemented on the second fuel injection. The calculated heat release is continuously compared with a reference and then the difference is converted to a duration correction of the fuel injection. This is done by a proportional controller which is initiated after the start of the second injection. By adding a perturbation on the first fuel injection the controller is shown to compensate during the second and thereby decreasing the cycle to cycle variations.
Development and Use of a Segregated-Solver for Detailed Modeling of End-Gas Detonation in a Lean-Burn Spark-Ignited Engine
Authors: Fiveland Scott B. , Vijayaraghavan Shriram , Shi Shaoping , Richardson Steven W. , McMillian Michael H. , Hiltner Joel D.
Published: January 2011

End-gas detonation occurs in a spark-ignited engine when the advancing flame front compresses the end-gas mixture to its autoignition temperature. The rapid energy release results in shock waves which are undesirable due to resulting combustion noise and boundary layer breakdown leading to reduced engine performance and incipient engine damage. In a spark-ignited engine, end-gas knock can result from improper combinations of compression ratio, spark timing or inlet thermodynamic conditions (i.e. manifold temperature, pressure, and equivalence ratio). These variables exhibit very complex interactions, which require costly high dimensional experimental designs for proper evaluation. As a result, detailed modeling tools are needed to predict the onset of the end-gas detonation regime for engine design applications. Developing a solver to predict the end-gas detonation of gases ahead of the flame front in an operating engine is not trivial. In theory, the model would need to simultaneously resolve both the detailed fluid mechanics as well as describe the fuel decomposition using detailed chemistry. Calculations for this type can take weeks or months depending on the number of dimensions that are resolved. Since hundreds of computations may be necessary to optimize a given configuration, it is necessary to be able to not only compute the onset of auto-ignition and other parameters accurately, but efficiently. The objective of this work was to develop an efficient methodology that could be utilized to effectively predict detonation in an internal combustion spark-ignited engine. This paper presents the computational methodology, a review of the combustion tool capability, and a comparison to experiments. The work clearly demonstrates the existence of inhomogeneities in the temperature field and discusses their impact on the prediction of end-gas knock.
Cylinder Individual Efficiency Estimation for Online Fuel Consumption Optimization
Authors: Lewander Magnus , Tunesta˚l Per , Johansson Bengt
Published: January 2011

Engine efficiency is often controlled in an indirect way through combustion timing control. This requires a priori knowledge of where to phase the combustion for different operating points and conditions. With cylinder individual efficiency estimation, control strategies aiming directly at fuel consumption optimization can be developed. This paper presents a method to estimate indicated efficiency using the cylinder pressure trace as input. The proposed method is based on a heat release calculation that takes heat losses into account implicitly using an estimated, CAD resolved polytropic exponent. Experimental results from a multi-cylinder engine show that with this approach, the estimated efficiency error is within 5% for all operating points tested. The final part of the paper is a discussion of how to use the efficiency estimation for feedback control. Different control concepts are presented as well as suggestions on how to handle the non-linear connection between combustion timing and indicated efficiency.
Nucleate Boiling Identification and Utilization for Improved Internal Combustion Engine Efficiency
Authors: Ajotikar Nikhil , Eggart Brian J. , Miers Scott A.
Published: January 2011

Internal combustion engines continue to become more compact and require greater heat rejection capacity. This demands research in cooling technologies and investigation into the limitations of current forced convection based cooling methods. A promising solution is the cooling strategy optimized with nucleate boiling to help meet these efficiency and emission requirements. Nucleate boiling results in an increased heat transfer coefficient, potentially an order of magnitude greater than forced convection, thereby providing improved cooling of an engine. This allows reduced coolant flow rates, increased efficiency, and reduced engine warm-up time. A study was conducted to characterize nucleate boiling occurring in the cooling passages of an IC engine cylinder head in a computational as well as experimental domain. The simulation was conducted to understand the physics of boiling occurring in an engine cooling passage and provide support for a potential boiling detection method. The computational fluid dynamics (CFD) simulation was performed for a simplified, two dimensional domain that resembled an engine cooling passage. The simulation results were followed by investigations of a pressure-based detection technique which was proven to be an effective method to detect boiling. An experimental test rig was used which consisted of a single combustion chamber section from a 5.4L V8 cylinder head. Water was used as the coolant. Results demonstrate the phase change physics involved in the boiling in an engine cooling passage, pressure variations in the coolant, heat flux data associated with the onset of nucleate boiling, and a comparison with existing boiling curves for water. Results of the simulation and experimental setup indicated that the change in energy and accompanying increase in pressure values can be related to bubble dynamics and thus provides a potential method to accurately detect nucleate boiling occurrence in an engine cooling system.