bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the Impact of Urban Development on Surface Temperature Using Remote Sensing in Ho Chi Minh City, Southern Vietnam
Authors: THI VAN TRAN , DUONG XUAN BAO HA
Published: August 2009

Rapid urbanisation and industrialisation have resulted in sharp land cover changes. Urban change not only impacts on land cover but also on urban climate. Land surface and atmospheric modifications due to urbanisation generally lead to a modified thermal climate that is warmer than the surrounding, non‐urbanised areas. In this research remote sensing technology was used to evaluate urban growth patterns and its thermal characteristics through mapping impervious surfaces and evaluating thermal infrared images. The case study was carried out in the northern part of Ho Chi Minh City, which has experienced accelerated urban development since the late 1980s. Landsat and Aster images were used to calculate variations in urban impervious surfaces from 1989 to 2006. Thermal bands were processed to obtain radiant surface temperatures for investigating the urban heat island effect associated with increasing impervious surfaces, both spatially and temporally. Impacts of urban development on surface temperature were shown by investigating the surface urban heat island effect intensity. The results show that the built‐up area in the northern part of Ho Chi Minh City expanded by 6.5 times between 1989 and 2006. Urban development has altered the magnitude and pattern of the surface urban heat island, with the highest land surface temperature cores found in the industrial (greater than 45oC) and urban areas (within 36oC and 40oC). In suburban and rural areas, where agricultural land still remains with full vegetation cover, the land surface temperature is usually lower. Using remote sensing, the impervious surface was extracted with overall accuracy and a Kappa coefficient for all three years greater than 96%, and the retrieved land surface temperatures with variations from in‐situ measurements of less than 2oC. The results presented here indicate that remote sensing can help to spatially monitor urban development and land surface temperature changes over the whole area and over a long period of time.
Quality of Sour Cream Packaged in Cups with Different Light Barrier Properties Measured by Fluorescence Spectroscopy and Sensory Analysis
Authors: Larsen Hanne , Tellefsen Siri Birgitte Geiner , Dahl Annette Veberg
Published: August 2009

ABSTRACT:  In this study, photooxidation of sour cream packaged in cups with different light barrier properties was investigated. The sour cream was light exposed for 36 h with a standard fluorescent light tube, simulating storage conditions in many Norwegian grocery stores. Three different cups were evaluated: a white cup, a cup with medium light barrier (LB), and a cup with high LB. The quality of the sour cream was evaluated by sensory analysis and front face fluorescence spectroscopy. The sour cream stored in white cups became very rancid during the light exposure, with a rancid flavor score of 7.8 on a scale from 1 to 9, where 9 is the highest intensity. Cups with high LB gave best protection against the light. The sensory assessors could not distinguish between sour cream stored in cups with high LB and sour cream stored in the dark. The rancid flavor intensity for the cups with medium LB was significantly different (P < 0.05) from both the white cup and the cup with high LB. The sensory flavor intensities indicated that with 36 h of light exposure, only a cup with high LB will protect the sour cream sufficiently. The fluorescence measurements corresponded well with the sensory analysis as the photosensitizers were somewhat degraded for sour cream stored in cups with medium LB and most degraded in the white cups. For the cups with high LB, the fluorescence peaks that originated from the photosensitizers were all intact.

PRACTICAL APPLICATION: Dairy products such as sour cream will develop off‐odor and taste faults (“sunlight taste”) in a few hours if exposed to sufficient fluorescent lightning in the grocery stores. A light barrier can be incorporated in the packaging material to protect the dairy products from the light. Our experiment showed that the incorporation of a black pigment into 1 of the 3 plastic layers in the cup for packaging of sour cream protected the sour cream from degradation when exposed to light.
Improving Foaming Properties of Yolk‐Contaminated Egg Albumen by Basic Soy Protein
Authors: Wang Guang , Wang Tong
Published: August 2009

ABSTRACT:  Yolk contamination of egg white is a common problem in the egg breaking industry. Foaming properties of egg white protein are affected by such contamination, but proteins of basic nature may restore the foaming properties of the yolk‐contaminated egg white protein. The purpose of this study was to chemically modify a soy protein, that is, to esterify the acidic groups on the protein and to study the potential of such modified protein in improving foaming. We showed that the modification changed the isoelectric point of soy protein isolate (SPI) from 4.5 to about 10. Sonication was proven to be a very effective means to redisperse the methanol‐denatured soy protein during reaction, as shown by the improved solubility profile. Such modified basic protein, that is, the sonicated‐modified SPI (SMSPI), when added to the yolk‐contaminated (at 0.4% level, as‐is basis) egg white, gave significantly improved foaming properties. We have shown that the slight change in pH due to the addition of SMSPI was not the reason for improved foaming performance; instead, the modified protein itself was the main reason for such improvement. Addition of SMSPI increased the foaming performance of both pure egg white and yolk‐contaminated egg white. SMSPI consistently performed better than the unmodified SPI for improving foaming. Addition of SMSPI (16%, based on dry egg white, and 1.6% based on liquid egg white) fully restored foam expansion and foam liquid stability of 0.4% yolk‐contaminated egg white, and it even out‐performed the foaming of pure white protein. Therefore, a feasible solution to restore the foaming properties of yolk‐contaminated egg white has been identified. It is expected that such modified SPI can be used as an additive or ingredient in foaming formulation, especially when the egg white protein is suspected of lipid contamination.
Effects of High‐Intensity Pulsed Electric Fields on Lipoxygenase and Hydroperoxide Lyase Activities in Tomato Juice
Authors: Aguiló‐Aguayo Ingrid , Soliva‐Fortuny Robert , Martín‐Belloso Olga
Published: August 2009

ABSTRACT:  The influence of high‐intensity pulsed electric field (HIPEF) parameters, namely, pulse frequency, pulse width, and polarity on tomato juice lipoxygenase (LOX) and hydroperoxide lyase (HPL) activities was studied using a response surface methodology. Samples were subjected to square‐shaped pulses of 35 kV/cm for 1000 μs, with pulse width ranging from 1 to 7 μs at frequencies from 50 to 250 Hz, either in monopolar or bipolar mode. Tomato LOX was more resistant to HIPEF than HPL within the range of assayed conditions. An increase in frequency or pulse width resulted in a decrease of both residual LOX (RALOX) and HPL (RAHPL) activities. The lowest RALOX (81%) was observed when tomato juice was treated at 250 Hz for 7 μs in bipolar mode. Moreover, the same conditions led to the highest HPL activity reduction (RAHPL = 10%). A validation of the predictive models determined that 2nd‐order expressions were accurate enough to fit the experimental results.
Inhibition of Siah2 ubiquitin ligase by vitamin K3 (menadione) attenuates hypoxia and MAPK signaling and blocks melanoma tumorigenesis
Authors: Shah Meera , Stebbins John L. , Dewing Antimone , Qi Jianfei , Pellecchia Maurizio , Ronai Ze’ev A.
Published: August 2009

The E3 ubiquitin ligase Siah2 has been implicated in the regulation of the hypoxia response, as well as in the control of Ras, JNK/p38/NF‐κB signaling pathways. Both Ras/mitogen‐activated protein kinase (MAPK) and hypoxia pathways are important for melanoma development and progression, pointing to the possible use of Siah2 as target for treatment of this tumor type. In the present study, we have established a high‐throughput electro‐chemiluninescent‐based assay in order to screen and identify inhibitors of Siah2 ubiquitin ligase activity. Of 1840 compounds screened, we identified and characterized menadione (MEN) as a specific inhibitor of Siah2 ligase activity. MEN attenuated Siah2 self‐ubiquitination, and increased expression of its substrates PHD3 and Sprouty2, with concomitant decrease in levels of HIF‐1α and pERK, the respective downstream effectors. MEN treatment no longer affected PHD3 or Sprouty2 in Siah‐KO cells, pointing to its Siah‐dependent effects. Further, MEN inhibition of Siah2 was not attenuated by free radical scavenger, suggesting it is ROS‐independent. Significantly, growth of xenograft melanoma tumors was inhibited following the administration of MEN or its derivative. These findings reveal an efficient platform for the identification of Siah inhibitors while identifying and characterizing MEN as Siah inhibitor that attenuates hypoxia and MAPK signaling, and inhibits melanoma tumorigenesis.
Automated quality evaluation of digital fundus photographs
Authors: Bartling Herman , Wanger Peter , Martin Lene
Published: August 2009

Purpose:  Retinal images acquired by means of digital photography are often used for evaluation and documentation of the ocular fundus, especially in patients with diabetes, glaucoma or age‐related macular degeneration. The clinical usefulness of an image is highly dependent on its quality. We set out to develop and evaluate an automatic method of evaluating the quality of digital fundus photographs.

Methods:  A method for making a numerical quantification of image sharpness and illumination was developed using Matlab™ image analysis functions. Based on their sharpness and illumination measures, 1000 fundus photographs, randomly selected from a clinical database, were assigned to four predefined quality groups (not acceptable, acceptable, good, very good). Six independent observers, comprising three experienced ophthalmologists and three ophthalmic nurses with extensive experience in fundus image acquisition, classified a selection of 100 of these images into the corresponding quality groups.

Results:  Automatic quality evaluation was more sensitive than evaluation by human observers in terms of ability to discriminate between good and very good images. The median concordance between the six human observers and the automatic evaluation was substantial (kappa = 0.64).

Conclusions:  The proposed method provides an objective quality assessment of digital fundus photographs which agrees well with evaluations made by qualified human observers and which may be useful in clinical practice.
Fine‐needle aspiration biopsy and other biopsies in suspected intraocular malignant disease: a review
Authors: Eide Nils , Walaas Lisa
Published: August 2009

Ocular oncologists require a strong indication for intraocular biopsy before the procedure can be performed because it carries a risk for serious eye complications and the dissemination of malignant cells. The purpose of this review is to evaluate the extent to which this restricted practice is supported by evidence from previous reports and to outline our main indications and contraindications. The different intraocular biopsy techniques in the anterior and posterior segment are discussed with a focus on our preferred method, fine‐needle aspiration biopsy (FNAB). In the literature, complications are typically under‐reported, which reduces the possibilities of evaluating the risks correctly and of making fair comparisons with other biopsy methods. In FNAB, the exact placement of the needle is critical, as is an accurate assessment of the size of the lesion. Fine‐needle aspiration biopsy is usually not a reliable diagnostic tool in lesions < 2 mm in thickness. It is very advantageous to have a cytopathologist present in the operating theatre or close by. This ensures adequate sampling and encourages repeated biopsy attempts if necessary. This approach reduces false negative results to < 3%. Adjunct immunocytochemistry is documented to increase specificity and is essential for diagnosis and management in about 10% of cases. In some rare pathological processes the diagnosis depends ultimately on the identification of specific cell markers. An accurate diagnosis may have a decisive influence on prognosis. The cytogenetic prognostications made possible after FNAB are reliable. Biopsy by FNA has a low complication rate. The calculated risk for retinal detachment is < 4%. Intraocular haemorrhage is frequently observed, but clears spontaneously in nearly all cases. Only a single case of epibulbar seeding of malignant cells at the scleral pars plana puncture site of transvitreal FNAB has been documented. Endophthalmitis has been reported and adequate standard preoperative preparation is obligatory. An open biopsy is still an option in the anterior segment, but has been abandoned in the posterior segment. Although vitrectomy‐based procedures are becoming increasingly popular, we recommend using FNAB as part of a stepwise approach. A vitrectomy‐assisted biopsy should be considered in cases where FNAB fails. In any adult patient with suspected intraocular malignancy in which enucleation is not the obvious treatment, the clinician should strive for a diagnosis based on biopsy. When the lesion is too small for biopsy or the risks related to the procedure are too great, it is reasonable to be reluctant to biopsy. The standards applied in the treatment of intraocular malignant diseases should be equivalent to those in other fields of oncology. Our view is controversial and contrary to opinion that supports current standards of care for this group of patients.
Novelties in Fissistigma (Annonaceae) from Borneo
Authors: Turner I. M.
Published: August 2009

Five new species of Fissistigma are described from Borneo. Fissistigma brevistipitatum sp. nov. is a species of lowland and hill forest mostly recorded from Sabah. Fissistigma bygravei sp. nov. is similar to F. hypoglaucum (Miq.) Merr. of the Malay Peninsula and Sumatra. Fissistigma carrii sp. nov. is from Mount Kinabalu. Fissistigma crassicaule is a robust plant known from a couple of collections from Sarawak. Fissistigma montanum sp. nov. is a species from hill and montane forest recorded from Brunei, Sabah and Sarawak. A new combination in Fissistigma is made for Melodorum multivenium Diels. Two recently described species of Fissistigma from Borneo (F. cordifolium Irawan and F. magnisepalum Irawan) are reduced to synonymy of Friesodielsia excisa (Miq.) Steenis and Friesodielsia affinis (Hook. f. & Thomson) D. Das, respectively. Both species of Friesodielsia are lectotypified.
Mitochondrial myopathy caused by clevudine therapy in chronic hepatitis B patients
Authors: Tak Won Young , Park Soo Young , Jung Min Kyu , Jeon Seong Woo , Cho Chang Min , Kweon Young Oh , Kim Sung Kook , Choi Yong Hwan
Published: August 2009

As a pyrimidine analog with potent and sustained antiviral activity against hepatitis B virus, clevudine has been known to have no effect on mitochondrial structure, DNA content, or function. There is little information on the side effects of clevudine, which has not been approved for the treatment of chronic hepatitis B outside of South Korea. We report here two cases of chronic hepatitis B patients who experienced mitochondrial myopathy after clevudine medication. These cases raise concerns about the safety profile of clevudine for the treatment of chronic hepatitis B.
Sensitivity and specificity of fasting ammonia and serum bile acids in the diagnosis of portosystemic shunts in dogs and cats
Authors: Ruland Kristina , Fischer Andrea , Hartmann Katrin
Published: August 2009

Background:Portosystemic shunt (PSS) is the most common cause of hepatic encephalopathy in dogs and cats. Fasting ammonia and serum bile acids (SBA) are used to diagnose PSS, but their true sensitivity and specificity have not been fully evaluated, especially in cats.

Objectives:The purpose of this study was to determine the diagnostic accuracy of fasting ammonia and SBA concentrations in the diagnosis of PSS in dogs and cats and to compare diagnostic accuracy between species.

Methods:A retrospective analysis of data from 373 dogs and 85 cats presented to the clinic from 1996 to 2006 was carried out. Based on clinical, laboratory, and imaging findings, animals were grouped as having PSS, parenchymal hepatic disease, or extrahepatic disease. The sensitivity and specificity of ammonia and SBA concentrations for the diagnosis of PSS were calculated and receiver‐operating characteristic analysis was used to optimize cut‐offs.

Results:Using the upper limit of laboratory reference intervals (ammonia, 59 μmol/L; SBA, 20  μmol/L), the sensitivity and specificity of ammonia was 85% and 86% in dogs, and 83% and 76% in cats, respectively. The sensitivity and specificity of SBA was 93% and 67% in dogs, and 100% and 71% in cats, respectively. Using optimal cut‐off points for ammonia (dogs, 57 μmol/L; cats, 94 μmol/L) the sensitivity and specificity was 91% and 84% in dogs and 83% and 86% in cats, respectively. Using optimal cut‐off points for SBA (dogs, 58 μmol/L; cats, 34  μmol/L) the sensitivity and specificity was 78% and 87% in dogs and 100% and 84% in cats.

Conclusion:Increased fasting ammonia and SBA concentrations are accurate indicators of PSS. An improvement in diagnostic accuracy can be achieved by using defined optimal cut‐off points for the selective diagnosis of PSS.
Surfing to Cross‐Cultural Awareness: Using Internet‐Mediated Projects to Explore Cultural Stereotypes
Authors: Abrams Zsuzsanna I.
Published: August 2009

Abstract:The Standards for Foreign Language Learning in the 21st Century stress that learning about culure is an integral part of learning a foreign language (L2); such exploration is a necessary bridge to gaining valuable insights about one's own culture as well as the culture(s) of the target language. Long‐term projects, for example, extended interviews with native speakers, enable learners to develop an understanding of another culture from an “emic” point of view (Barro et al., 1993; Robinson‐Stuart & Nocon, 1996; Wright, 2000). For many U.S. students, however, neither native speaker informants in U.S. cities nor study abroad programs are available or accessible. This study explores Internet‐based culture portfolios that bring insider's views of other cultures into the 12. classroom. In this study, learners enrolled in third‐semester German language courses conducted semester‐long culture projects, in which they explored their stereotypical views of the cultures of Germany, Austria, and Switzerland. Learners investigated the extent to which these stereotypes might apply, using media from these countries and from their own cultural contexts, library, Internet resources, and online interviews with members of the cultures in Germany. The results of this study indicate that the Internet‐based culture project promoted learners' acquisition of new cultures from an emic perspective.
Evaluation of Professional Development for Language Teachers in California
Authors: Lozano Albert S. , Sung Hyekyung , Padilla Amado M. , Silva Duarte M.
Published: August 2009

Abstract: The California Foreign Language Project (CFLP), established in 1988 by the California legislature, is a professional development program designed to improve and expand foreign language teaching in California while promoting access and equity within educational institutions for every student. As one of the nine content areas of the California Subject Matter Project, CFLP is a voluntary project that served 609 elementary, secondary, and postsecondary foreign language teachers from 43 counties in 1998/1999. This article describes the origin and rationale of the California Foreign Language Project and discusses the importance of professional development programs, a topic of growing interest given the nationwide focus on student performance and school reform. Finally, the components of professional development program evaluation, and specifically of CFLP's Evaluation Design, will be presented, along with the findings from the 1998/1999 program year.
Teaching Gambits: The Effect of Instruction and Task Variation on the Use of Conversation Strategies by Intermediate Spanish Students
Authors: Taylor Gregory
Published: August 2009

Abstract: Gambits are words or phrases that facilitate the flow of conversation by giving the speaker time to organize his or her thoughts, maintain or relinquish the floor, expound on an argument, or specify the function of a particular utterance. This study, based in part on previous research by Wildner‐Bassett (1984), examined (1) whether gambit use in Spanish can be taught effectively in the classroom, allowing the student to use gambits appropriately in unplanned speech; (2) how the type of interactional situation (a friendly discussion versus a complaint) affects the production of gambits; and (3) what types of gambits show the greastest increases in use for each interactional situation. Participants were intermediate students. A repeated‐measures design was used. Results suggest that students can be taught to use gambits effectively and appropriately in the classroom. In addition, the nature of the interactional situation seemed to make a difference in the ability of the students to produce gambits in spontaneous interaction and in the types of gambits they produced.
The Effects of Using Two Advance Organizers with Video Texts for the Teaching of Listening in English
Authors: Chung Jing‐mei
Published: August 2009

Abstract: Research has confirmed that exposing students to authentic materials through video aids language learning, especially listening skills. This study investigates the effects of two advance organizers — question previewing and vocabulary preteaching — on Taiwanese college students' listening comprehension of English‐language videotapes. Approximately 188 college students, randomly assigned to one of four treatment groups, viewed two video episodes, each twice. The results suggest that the group exposed to a combined treatment of vocabulary preteaching and question previewing between two video viewings outperformed the groups who received either the vocabulary preteaching alone or no treatment on both multiple‐choice and open‐ended tests. However, the effects of question previewing are likely to be assessment task‐dependent. The implications of the findings for listening instruction employing video in the EFL classroom are discussed.
Lean-Burn Stationary Natural Gas Reciprocating Engine Operation With a Prototype Fiber Coupled Diode End Pumped Passively Q-Switched Laser Spark Plug
Authors: McIntyre Dustin L. , Woodruff Steven D. , Ontko John S.
Published: August 2009

An end pumped passively Q-switched laser igniter was developed to meet the ignition system needs of large bore lean burn stationary natural gas engines. The laser spark plug used an optical fiber coupled diode pump source to axially pump a passively Q-switched Nd:YAG laser and transmit the laser pulse through a custom designed lens. The optical fiber coupled pump source permits the excitation energy to be transmitted to the spark plug at relatively low optical power, less than 250 watts. The Q-switched laser then generates as much as 8 millijoules of light in 2.5 nanoseconds which is focused through an asymmetric biconvex lens to create a laser spark from a focused intensity of approximately 225 GW/cm2. A single cylinder engine fueled with either natural gas only or hydrogen augmented natural gas was operated with the laser spark plug for approximately 10 hours in tests spanning 4 days. The tests were conducted with fixed engine speed, fixed boost pressure, no exhaust gas recirculation, and laser spark timing advance set at maximum brake torque timing. Engine operational and emissions data were collected and analyzed.
Assessment of Multi-Objective Genetic Algorithms With Different Niching Strategies and Regression Methods for Engine Optimization and Design
Authors: Shi Yu , Reitz Rolf D.
Published: August 2009

In previous study [1] the Non-dominated Sorting Genetic Algorithm II (NSGA II) [2] performed better than other popular Multi-Objective Genetic Algorithms (MOGA) in engine optimization that sought optimal combinations of the piston bowl geometry, spray targeting, and swirl ratio. NSGA II is further studied in this paper using different niching strategies that are applied to the objective-space and design-space, which diversify the optimal objectives and design parameters accordingly. Convergence and diversity metrics are defined to assess the performance of NSGA II using different niching strategies. It was found that use of the design niching achieved more diversified results with respect to design parameters, as expected. Regression was then conducted on the design datasets that were obtained from the optimizations with two niching strategies. Four regression methods, including K-nearest neighbors (KN), Kriging (KR), Neural Networks (NN), and Radial Basis Functions (RBF), were compared. The results showed that the dataset obtained from optimization with objective niching provided a more fitted learning space for the regression methods. The KN, KR, outperformed the other two methods with respect to the prediction accuracy. Furthermore, a log transformation to the objective-space improved the prediction accuracy for the KN, KR, and NN methods but not the RBF method. The results indicate that it is appropriate to use a regression tool to partly replace the actual CFD evaluation tool in engine optimization designs using the genetic algorithm. This hybrid mode saves computational resources (processors) without losing optimal accuracy. A Design of Experiment (DoE) method (the Optimal Latin Hypercube method) was also used to generate a dataset for the regression processes. However, the predicted results were much less reliable than results that were learned using the dynamically increasing datasets from the NSGA II generations. Applying the dynamical learning strategy during the optimization processes allows computationally expensive CFD evaluations to be partly replaced by evaluations using the regression techniques. The present study demonstrates the feasibility of applying the hybrid mode to engine optimization problems, and the conclusions can also extend to other optimization studies (numerical or experimental) that feature time-consuming evaluations and have highly non-linear objective-spaces.
Advanced Wear Measurement Technique for Compression Ring Bottom Flank Wear
Authors: Rabassa Erich , Karrip Kimm , Vander Veen Greg
Published: August 2009

Diesel engine technology advancements in performance and requirements for meeting emission regulations have developed new challenges for piston system durability. Increased combustion pressure and exhaust gas recirculation have severely increased the demand of the top piston ring to top piston groove surface interactions. This more demanding environment has resulted in new needs for improved durability and compatibility of the bottom flank of the top piston ring and the bottom side to the top piston groove. Developments in materials and treatments of these surfaces require accurate analysis and assessment of the worn regions. With this demand, new measurement techniques have been deployed to accurately map the bottom flank of the top piston ring and the bottom side of the top piston groove. The new methods allow for volumetric wear measurements and regional analysis for wear step magnitudes to assist in better material wear characterization as well as piston ring design influence.
Investigation of Design Parameters in Partially Premixed Compression Ignition Combustion Using Adaptive Injection Strategies
Authors: Kokjohn Sage L. , Reitz Rolf D.
Published: August 2009

Premixed combustion strategies have been shown to yield very low NOx and soot emissions, while maintaining diesel-like efficiency; however, several issues must be addressed before they can gain widespread acceptance. This paper provides guidelines for solving problems with premixed combustion strategies, viz.: lack of combustion phasing control, excessive pressure rise rate, and spray wall impingement due to early injections. Cooled EGR and a multiple injection concept is used to control combustion phasing and reduce the peak pressure rise rate. To address spray-wall impingement, an Adaptive Injection Strategy (AIS) is employed. This strategy uses two injection pulses at different injection pressures to prepare an optimal in-cylinder mixture. The first injection is early in the cycle and utilizes a low injection pressure to minimize spray-wall impingement and create a well mixed charge. The second injection is near TDC and uses a high injection pressure in order to promote air entrainment and droplet dispersion. This study uses a multi-dimensional CFD code coupled with detailed chemistry, the KIVA-CHEMKIN code, to investigate the effects of several influential design parameters and identify emissions and performance tradeoffs. The combustion process considered is at a light load operating condition (nominal IMEP of 5.5 bar and high speed, 2000 rev/min). The parameters studied were: first and second pulse injection pressure and timing, IVC timing, EGR rate, fuel split, swirl ratio, and spray targeting. The investigation showed that the use of low pressure injections early in the cycle allows improved flexibility in fuel quantity and injection timing. An improved solution was found with near zero NOx and soot, a net ISFC of only 175 g/kW-hr, and a peak pressure rise rate of ∼8 bar/deg.
Kinetic Study of the Thermo-Oxidative Degradation of Squalane (C30H62) Modelling the Base Oil of Engine Lubricants
Authors: Diaby Moussa , Sablier Michel , Le Negrate Anthony , El Fassi Mehdi
Published: August 2009

On the basis of ongoing research conducted on the clarification of processes responsible for lubricant degradation in the environment of piston grooves in EGR diesel engines, an experimental investigation was aimed to develop a kinetic model which can be used for the prediction of lubricant oxidative degradation correlated to endurance test conducted on engines. Knowing that base oils are a complex blend of paraffins and naphtenes with a wide range of sizes and structures, their chemistry analysis during the oxidation process can be highly convoluted. In the present work, investigations were carried out with the squalane (C30H62) chosen for its physical and chemical similarities with the lubricant base oils used during the investigations. Thermo-oxidative degradation of this hydrocarbon was conducted at atmospheric pressure in a tubular furnace, while varying temperature and duration of the tests in order to establish an oxidation reaction rate law. The same experimental procedures was applied to squalane doped with two different phenolic antioxidants usually present in engine oil composition: 2,6-di-tert-butyl-4-methylphenol (BHT), and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (OBHP). Thus, the effect of both antioxidants on the oxidation rate law was investigated. Data analysis of the oxidized samples (FTIR spectroscopy, gas chromatography/mass spectrometry GC/MS) allowed to rationalize the thermo-oxidative degradation of squalane. The resulting kinetic modelling provides a practical analytical tool to follow the thermal degradation processes, which can be used for prediction of base oil hydrocarbon ageing. If experiments confirmed the role of phenolic additives as an affective agent to lower oxidation rates, the main results lay in the observation of a threshold temperature where a reversed activity of these additives was observed.
Low NOx and Low Smoke Operation of a Diesel Engine Using Gasoline-Like Fuels
Authors: Kalghatgi Gautam , Hildingsson Leif , Johansson Bengt
Published: August 2009

Much of the technology in advanced diesel engines, such as high injection pressures, is aimed at overcoming the short ignition delay of conventional diesel fuels to promote premixed combustion in order to reduce NOx and smoke. Previous work in a 2 litre single cylinder diesel engine with a compression ratio of 14 has demonstrated that gasoline fuel, because of its high ignition delay, is very beneficial for premixed compression ignition compared to a conventional diesel fuel. We have now done similar studies in a smaller — 0.537 litre — single cylinder diesel engine with a compression ratio of 15.8. The engine was run on three fuels of very different auto-ignition quality — a typical European diesel fuel with a cetane number (CN) of 56, a typical European gasoline of 95 RON and 85 MON with an estimated CN of 16 and another gasoline of 84 RON and 78 MON (estimated CN of 21). The previous results with gasoline were obtained only at 1200 rpm — here we compare the fuels also at 2000 rpm and 3000 rpm. At 1200 rpm, at low loads (∼4 bar IMEP) when smoke is negligible, NOx levels below 0.4 g/kWh can be easily attained with gasoline without using EGR while this is not possible with the 56 CN European diesel. At these loads, the maximum pressure rise rate is also significantly lower for gasoline. At 2000 rpm, with 2 bar absolute intake pressure, NOx can be reduced below 0.4 g/kWh with negligible smoke (FSN <0.1) with gasoline between 10 and 12 bar IMEP using sufficient EGR while this is not possible with the diesel fuel. At 3000 rpm, with the intake pressure at 2.4 bar absolute, NOx of 0.4 g/KWh with negligible smoke was attainable with gasoline at 13 bar IMEP. Hydrocarbon and CO emissions are higher for gasoline and will require after-treatment. High peak heat release rates can be alleviated using multiple injections. Large amounts of gasoline, unlike diesel, can be injected very early in the cycle without causing heat release during the compression stroke and this enables the heat release profile to be shaped.
Numerical Study of Fuel Composition Effects on Low Temperature Diesel Combustion With a Discrete Multi-Component Vaporization Model
Authors: Ra Youngchul , Reitz Rolf D.
Published: August 2009

A numerical investigation of fuel composition effects on diesel engine combustion is presented. A new discrete multi-component (DMC) fuel model was used to represent the properties and composition of multi-component diesel fuels. A multi-dimensional CFD code, KIVA-ERC-Chemkin, that is coupled with improved sub-models and the Chemkin library, was employed for the simulations. A small-bore, high-speed DI diesel engine operating in a low temperature combustion (LTC) regime was simulated with four different diesel fuels using a 6-component fuel model. The oxidation chemistry was calculated using a reduced mechanism for primary reference fuel, with the reaction rate coefficients adjusted to account for the Cetane number (CN) variation of the fuels of interest. The major property differences of the fuels include volatility, viscosity, and autoignitability. The predicted pressure, heat release rate, and emissions are compared with experimental data available in the literature. The results show that the present multi-component fuel model performs reliably, and captures the effects of fuel composition differences on combustion. The emissions trends for the different fuels were also in good agreement with the corresponding experimental measurements. The results also indicate that, in addition to more realistic predictions of the fuel physical properties, further improvements of the chemical characteristics of the fuel components is desirable.
CFD Methodology Assessment for the Investigation of Convective Heat Transfer Properties of Engine Coolants Under Boiling Conditions
Authors: Fontanesi Stefano , Malaguti Simone , McAssey E. V.
Published: August 2009

The paper presents a combined experimental and numerical program directed at defining a cost/effective methodology for conjugate heat transfer CFD simulations of engine water cooling jackets. As a first step in the process, deficiencies in current numerical strategies for the analysis of conjugate heat transfer problems under typical engine operating conditions are exposed and commented. Results are shown form a wide validation program based on the comparison between experimental measurements from a test facility at Villanova University and CFD predictions at the University of Modena. On the experimental side, the test apparatus consists of a test section, pump, accumulator tank, rejection heat exchanger and required pumping. The test section is provided with a constant volumetric flow rate, and consists of a cylindrical aluminum body with a drilled horizontal flow channel. The section is heated by ten cartridge heaters located at a constant radial distance from the cylinder axis. The test section is connected to the flow loop by means of two calming sections, respectively at the cylinder inlet and exit. Twenty thermocouples are used to measure the test section local temperature along a radial plane cutting the cylinder. Water / ethylene-glycol binary mixture and pure water are tested and compared during the experimental program, in order to reproduce a set of thermal situations as close as possible to actual engine cooling system operation. On the CFD side, an extensive program reproducing the experiments is carried out in order to assess the predictive capabilities of some of the most commonly used eddy viscosity models available in literature. Both non-evaporating and evaporating conditions are tested, showing severe limitations to the use of simplified boiling models to correctly capture the complex interaction between turbulent boundary layer and vapor bubble dynamics. In order to overcome the above stated deficiencies under boiling conditions, a methodology is then proposed to both improve the accuracy of the CFD forecasts and reduce the computational costs of the simulations. A few preliminary results from the validation process are shown and briefly discussed at the end of the paper.
Connecting Rod Big End Design Using Finite Element Analysis and Bench Testing Validation
Authors: Seaberg Wayne G.
Published: August 2009

Dresser Waukesha has designed a new connecting rod for implementation on the VHP series of natural gas engines. The connecting rod design process was driven by feature based solid models which were readily accessed for finite element structural analysis, rapid prototyping, and production tooling procurement in order to minimize the overall development time. The main objectives of the design effort were higher speed/power rating capability and assembly compatibility with existing 8.50 inch and 9.375 inch bore field engines in both a lean burn and rich burn operating condition. This paper discusses the advanced utilization of finite element analysis and bench testing techniques to expedite the design and test validation process.
A Continuous Multi-Component Fuel Flame Propagation and Chemical Kinetics Model
Authors: Yang Shiyou , Reitz Rolf D.
Published: August 2009

A continuous multi-component fuel flame propagation and chemical kinetics model has been developed. In the multicomponent fuel model, the theory of continuous thermodynamics was used to model the properties and composition of fuels such as gasoline. The difference between the current continuous multi-component fuel model and previous similar models in the literature is that the source terms contributed by chemistry in the mean and the second moment transport equations have been considered. This new model was validated using results from a discrete multi-component fuel model. In the flame propagation and chemical kinetics model, five improved combustion sub-models were also integrated with the new continuous multi-component fuel model. To consider the change of local fuel vapor mixture composition, a “PRF adaptive” method is proposed that formulates a relationship between the fuel vapor mixture PRF number (or octane number) and the fuel vapor mixture composition based on the mean molecular weight and/or variance of the fuel vapor mixture composition in each cell. Simulations of single droplet vaporization with a single-component fuel (iso-octane) were compared with multi-component fuel cases.
Development of the Dresser Waukesha 16V150LTD Engine for Bio-Gas Fuels
Authors: Reinbold Edward , von der Ehe James
Published: August 2009

Dresser Waukesha released the 16V150LTD engine for operation on pipeline natural gas in 2006. The engine has since been developed for operation on low Btu Bio gas fuels; including landfill and digester applications for both 50 and 60 Hz operation. This paper discusses the development of the engine fuel system, calibration changes, and test results of the Bio-gas 16V150LTD. Fuel system modifications were made for the higher fuel flow rates and calibration changes were necessary to meet performance requirements across the heating value range. Test results are presented which discuss the effects of the lower heating value bio-gas fuels on combustion and engine performance.
Correlation of Power Cylinder Modeling to Empirical Measurements in a John Deere 6135H 13.5L I-6 Engine
Authors: Maschewske Max , Rabassa Erich , Karrip Kimm , Vander Veen Greg , Lunsford Randy , Sanborn Mark
Published: August 2009

Motivated by the need to achieve greater efficiency in the product development cycle, engine manufacturers in the heavy-duty industry are relying more and more on analytical tools to help resolve performance issues, minimize testing costs and reduce time to market. This is particularly the case in the area of power cylinder development, since the physical phenomena occurring within the cylinders are difficult to observe and quantify. However, analytical tools are useful only if they are able to accurately represent the physical systems that they are supposed to simulate. It therefore becomes critical to establish a correlation between model predictions and empirical measurements. To this end, a correlation study was initiated comparing power cylinder analytical modeling results to empirical measurements in a John Deere 6135H 13.5L I-6 engine. The engine test measurements that were carried out included cylinder pressure, piston land pressure, engine blowby, and lube oil consumption. The correlation parameters considered in the study included piston land gas pressures, power cylinder contribution to engine blowby, and lube oil consumption mechanisms.
Controlling Lubricant Acidity With an Oil Conditioning Filter
Authors: Watson Simon A. G. , Wong Victor W. , Brownawell Darrell , Lockledge Scott P.
Published: August 2009

In modern diesel engines, acidity generally determines the lubricant drain interval. To control acidity, lubricant suppliers incorporate detergent additives to neutralize acids that accumulate in the oil via exhaust blow-by and base-stock oxidation. However, formulations that meet the most recent diesel lubricant classification specifications typically contain lower levels of detergent since this additive contributes to ash that fouls emissions aftertreatment systems. This study explores a novel approach to lubricant acid control as a potential means to reduce additive requirements or increase oil drain interval. The authors investigate the performance of an innovative oil filter that releases no additives into the lubricant, yet enhances the acid control function typically performed by detergent and dispersant additives. The filter chemically conditions the crankcase oil during engine operation by sequestering acidic compounds derived from engine combustion and lubricant degradation. Long duration heavy-duty diesel engine tests show that the filter reduces both the rate of Total Base Number (TBN) decline and the rate of Total Acid Number (TAN) increase by a factor of two. Analysis by Fourier transform infra-red (FTIR) spectroscopy also indicates that lubricant oxidation may be lowered. In addition, these results suggest a reduction in engine wear. These results imply that lower lubricant additive levels in combination with this novel oil filter may be used to reduce ash accumulation in diesel aftertreatment systems, while maintaining adequate engine protection. The results also indicate that the engine operator may use this oil filter with a state-of-the art lubricant to lengthen oil change intervals.
Model-Based Assessment of Two Variable CAM Timing Strategies for HCCI Engines: Recompression vs. Rebreathing
Authors: Babajimopoulos Aristotelis , Prasad Challa V. S. S. , Lavoie George A. , Assanis Dennis N.
Published: August 2009

The paper discusses the development and application of a single-cylinder HCCI engine model within the framework of a 1-D engine simulation software (GT-Power®). The HCCI combustion model includes a predictive burn model based on the in-cylinder conditions, along with methods to estimate in-cylinder NOx production and ringing intensity. The validation of the model was done by comparing simulation results with available experimental data, highlighting the comparison between two different HCCI variable cam timing strategies (recompression and rebreathing). A comparative study of the two valve strategies was carried out with the validated model and the entire operational range of the strategies was compared and analyzed for the constraints that limit further load extension. Recompression was found to be more efficient than rebreathing in the low load operating region. However, the rebreathing strategy was found to span a wider operational range compared to recompression at all speeds.
Combining Instantaneous Temperature Measurements and CFD for Analysis of Fuel Impingement on the DISI Engine Piston Top
Authors: Cho Kukwon , Grover Ronald O. , Assanis Dennis , Filipi Zoran , Szekely Gerald , Najt Paul , Rask Rod
Published: August 2009

A two-pronged experimental and computational study was conducted to explore the formation, transport, and vaporization of a wall film located on the piston surface within a four-valve, pent roof, direct-injection spark-ignition (DISI) engine, with the fuel injector located between the two intake valves. Negative temperature swings were observed at three piston locations during early injection, thus confirming the ability of fast-response thermocouples to capture the effects of impingement and heat loss associated with fuel film evaporation. Computational Fluid Dynamic (CFD) simulation results demonstrated that the fuel film evaporation process is extremely fast under conditions present during intake. Hence, the heat loss measured on the surface can be directly tied to the heating of the fuel film and its complete evaporation, with the wetted area estimated based on CFD predictions. This finding is critical for estimating the local fuel film thickness from measured heat loss. The simulated fuel film thickness and transport corroborated well temporally and spatially with measurements at thermocouple locations directly in the path of the spray, thus validating the spray and impingement models. Under the strategies tested, up to 23% of fuel injected impinges upon the piston and creates a fuel film with thickness of up to 1.2 μm. In summary, the study demonstrates the usefulness of heat flux measurements to quantitatively characterize the fuel film on the piston top and allows for validation of the CFD code.