bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Average Molecular Weights for Product Categories to Predict Freezing Characteristics of Foods
Authors: Boonsupthip Waraporn , Sajjaanantakul Tanaboon , Heldman Dennis R.
Published: August 2009

ABSTRACT:  In the design of food freezing process, food property parameters, initial freezing temperature (TFi), and frozen water fraction (XI) are required. The predictive approaches of these 2 parameters have been developed based on mass fractions and molecular weights of specific food components such as proteins, carbohydrates, minerals, and acids/bases. In this study, the molecular weights of the key mineral and acid/base components were successfully represented using average molecular weights () and 4 TFi and XI calculation approaches were proposed. Based on an analysis of 212 food products, the absolute differences (AD) between the experimental and predicted TFi values for the 4 approaches were small. The prediction for the food model category was excellent with average AD () values as low as ± 0.03 °C. For the other food categories, the prediction efficiency was impressive with values between ± 0.22 and ± 0.38 °C. The predicted relationship between temperature and XI for all analyzed food products provided close agreements with experimental data.
Development of a Solid‐Phase Extraction–Enzyme‐Linked Immunosorbent Assay for the Determination of 17β‐19‐Nortestosterone Levels in Antifatigue Functional Foods
Authors: Zhang Yan , Pan Tao , Fang Guozhen , Ma Dongyue , Wang Shuo
Published: August 2009

ABSTRACT: 17β‐19‐nortestosterone (17β‐NT) has been illegally used in antifatigue functional foods to promote muscle growth and improve endurance. A rapid and sensitive solid‐phase extraction–enzyme‐linked immunosorbent assay (SPE‐ELISA) method was developed and successfully applied to analyze the levels of 17β‐NT in antifatigue functional foods. A polyclonal antibody against 17β‐NT was produced from rabbits immunized with the 17β‐NT‐BSA conjugate, and a competitive direct enzyme‐linked immunosorbent assay was developed for the rapid detection of 17β‐NT. The concentration causing 50% inhibition (IC50) and the limit of detection (LOD) were found to be 0.08 and 0.0055 ng/mL, respectively; this was better than methods previously reported that had a LOD of 2.4 ng/mL. C18cartridges were investigated for use in removing the effects of matrix in foods, and the sample purification protocol was optimized. Using the developed SPE‐ELISA method, recoveries of functional food samples were obtained in the range of 71% to 91.5%. Moreover, 2 kinds of antifatigue functional foods were analyzed using the established ELISA and HPLC methods. The correlation coefficient of the results obtained using the 2 methods was greater than 0.98. Thus, the preliminary evaluation of the SPE‐ELISA method proved that it is a specific, sensitive, and precise tool that can be used for the practical detection of 17β‐NT in various antifatigue functional food samples.
Strategies for enhancing bioluminescent bacterial sensor performance by promoter region manipulation
Authors: Yagur‐Kroll Sharon , Bilic Benny , Belkin Shimshon
Published: August 2009

Bioluminescent bacterial sensors are based upon the fusion of bacterial bioluminescence (lux) genes, acting as a reporter element, to selected bacterial stress‐response gene promoters. Depending upon the nature of the promoter, the resulting constructs react to diverse types of environmental stress, including the presence of toxic chemicals, by dose‐dependant light emission. Two bacterial sensors, harbouring sulA::luxCDABE and grpE::luxCDABE fusions, activated by the model chemicals nalidixic acid (NA) and ethanol, respectively, were subjected to molecular manipulations of the promoter region, in order to enhance the intensity and speed of their response and lower their detection thresholds. By manipulating the length of the promoter‐containing segment (both promoters), by introducing random or specific mutations in the promoter sequence or by duplicating the promoter sequence (sulA only), major improvements in sensor performance were obtained. Improvements included significantly enhanced sensitivity, earlier response times and an increase in signal intensity. The general approaches described herein may be of general applicability for optimizing bacterial sensor performance, regardless of the sensing or reporting elements employed.
Hybridization and invasion: one of North America’s most devastating invasive plants shows evidence for a history of interspecific hybridization
Authors: Blair Amy C. , Hufbauer Ruth A.
Published: August 2009

Hybridization has been hypothesized to influence invasion through the generation of novel phenotypes and/or increased levels of genetic variance. Based on morphology, hybrids between diffuse knapweed and spotted knapweed, two invasive plants in North America, are present in the invaded range. Some individuals within most diffuse knapweed sites in North America exhibit intermediate diffuse × spotted floral morphology. We examined hybridization at the molecular level, using amplified fragment length polymorphisms. Approximately a quarter of the assayed North American diffuse knapweed individuals exhibited evidence of introgression from spotted knapweed. However, plants with intermediate morphology did not show evidence of mixed ancestry more often than the plants with typical diffuse knapweed morphology. The high proportion of hybrid individuals in North American diffuse knapweed sites found here, combined with evidence from recent studies, suggests that diffuse knapweed was likely introduced with admixed individuals, and the hybrids are not newly created postintroduction. A century of backcrossing with diffuse knapweed has likely decoupled the relationship between morphology and admixture at the molecular level. In contrast to the scenario encountered in North America, in the native range where diploid diffuse and spotted knapweed overlap, hybrid swarms are common. In such sites, the floral phenotype aligns more closely with the genotype.
The Impact of Nonclinical Factors on Care Use for Patients with Depression: A STAR*D Report
Authors: Kashner T. Michael , Trivedi Madhukar H. , Wicker Annie , Fava Maurizio , Wisniewski Stephen R. , Rush A. John
Published: August 2009

Introduction: This article presents baseline findings that describe how nonclinical factors were associated with patient use of psychiatric and general medical care and how those relationships changed after patients enrolled in the 41‐site Sequenced Treatment Alternatives to Relieve Depression study (STAR*D). Aims: STAR*D offered adult outpatients with major depression diligently delivered, measurement‐based care. To achieve full remission within a tolerable medication dose, recommendations for treatment based on routine symptom and side‐effect measurements were discussed with patients by clinical research coordinators and offered to clinicians who could flexibly tailor that guidance to accommodate individual patient needs. Medications were provided gratis. Pre‐ and post‐enrollment data came from provider records and from patient face‐to‐face, telephone, and computer‐assisted surveys. Two‐part nested mixed models assessed patient likelihood and volume of mental and general medical care services. Results: Prior to enrollment, predisposing (gender, race, education, and care attitude), affordability (private insurance), and clinical factors (depressive symptoms and mental and physical functioning) were found to be important drivers of patient use of psychiatric and general medical care. After STAR*D enrollment, however, predisposing factors were less important drivers of psychiatric service use but remained important drivers of general medical care. Conclusions: Data suggest diligent, measurement‐based mental health programs may reduce race, gender, and education disparities in the use of needed mental health care.
Clinical significance of serum ornithine carbamoyltransferase in patients with non‐alcoholic steatohepatitis
Authors: Tokushige Katsutoshi , Hashimoto Etsuko , Noto Haruka , Yatsuji Satoru , Tobari Maki , Torii Nobuyuki , Taniai Makiko , Shiratori Keiko , Murayama Hiroshi
Published: August 2009

Aim:  Ornithine carbamoyltransferase (OCT) is reported to be a liver‐specific marker for the evaluation of hapatocellular damage. In this study, we investigated its clinical significance in non‐alcoholic steatohepatitis (NASH).

Methods:  Serum OCT levels were measured by the ELISA (enzyme‐linked immunosorbent assay) method. One hundred and twenty patients with NASH (18 liver cirrhosis induced by NASH and 9 NASH combined with hepatocellular carcinoma) were measured.

Results:  The serum levels of OCT and the ratios of OCT : alanine amino transferase (ALT) and OCT : aspartate amino transferase (AST) were increased in parallel with the progression of NASH. Especially, OCT and both ratios were markedly increased in hepatocellular carcinoma. As for the relationship between fibrosis grade and OCT, the serum OCT levels and the ratio of OCT : ALT levels were increased in parallel with liver fibrosis. In NASH patients with ALT within normal range, about 30% showed elevation of OCT.

Conclusion:  Serum OCT levels and the ratios of OCT : ALT and OCT : AST increase in parallel with the progression of NASH. It was suggested that OCT is a useful marker in the progression of NASH.
Alternate Pathway of Infection with Hepatozoon americanum and the Epidemiologic Importance of Predation
Authors: Johnson E.M. , Panciera R.J. , Allen K.E. , Sheets M.E. , Beal J.D. , Ewing S.A. , Little S.E.
Published: August 2009

Background: The range of American canine hepatozoonosis (ACH) is expanding from the southern USA northward. Transmission of Hepatozoon americanum occurs by ingestion of infected Gulf Coast ticks, Amblyomma maculatum. The source of the protozoan for the tick remains undetermined; infected dogs are unusual hosts for the tick.

Objective: Compare possible sources of infection by field investigations of 2 multiple‐dog outbreaks of ACH.

Animals: Twenty‐eight privately owned dogs (Canis familiaris), 1 coyote (Canis latrans), 31 wild‐trapped cotton rats (Sigmodon hispidus), 24 wild‐trapped field mice (Peromyscus leucopus), and 9 wild‐caught rabbits (Sylvilagus spp.) from sites in eastern Oklahoma were monitored for hepatozoonosis. Six laboratory‐raised cotton rats (S. hispidus), 6 Sprague‐Dawley rats (Rattus norvegicus), 6 C57BL/6J‐Lystbg‐J/J mice (Mus musculus), 6 outbred white mice (M. musculus), 6 New Zealand white rabbits (Oryctolagus cuniculus), and 2 dogs were acquired through commercial vendors for experimental transmission trials of H. americanum.

Methods: Four of 15 dogs in a rural neighborhood and 5/12 hunting Beagles were confirmed to be infected by blood smear examination, muscle biopsy, and polymerase chain reaction assay of the 18S rRNA gene of Hepatozoon species. Histories and tick host preferences led to field collections of common prey of canids and experimental transmission trials of H. americanum to selected prey (M. musculus, S. hispidus, R. norvegicus, and O. cuniculus).

Results: Dogs with ready access to prey (4/15 dogs) or that were fed prey retrieved from hunts (5/12 hunting Beagles) became infected, providing evidence that predation is an important epidemiologic component of ACH infection. Experimental transmission studies identified a quiescent, infectious stage (cystozoite) of the parasite that provides an alternate mode of transmission to canids through predation, demonstrating that cotton rats, mice, and rabbits but not brown rats may act as paratenic hosts of H. americanum.

Conclusions and Clinical Importance: Predation of prey harboring infected A. maculatum or containing cystozoites of H. americanum in their tissues provide 2 modes of transmission of ACH to dogs, putting unconfined dogs at increased risk of infection in endemic areas.
Dacarbazine as Single‐Agent Therapy for Relapsed Lymphoma in Dogs
Authors: Griessmayr P.C. , Payne S.E. , Winter J.E. , Barber L.G. , Shofer F.S.
Published: August 2009

Background: Multidrug resistance is the most common cause of treatment failure in dogs with multicentric lymphoma. 5‐(3,3‐Dimethyl‐1‐triazeno)‐imidazole‐4‐carboxamide (DTIC) is an atypical alkylator used as standard treatment in human Hodgkin's lymphoma, and has been effective in combination treatment to treat resistant lymphoma in dogs. However, no data are available on the use of DTIC as a single agent in the treatment of relapsed canine lymphoma.

Hypothesis: Single‐agent DTIC is effective and safe in treating dogs with lymphoma that relapsed or failed to respond to previous chemotherapy.

Animals: Forty client‐owned dogs with relapsed lymphoma.

Methods: Dogs were eligible for the retrospective study if they had a histologically or cytologically confirmed diagnosis of lymphoma and had relapsed. Dogs received DTIC (800–1,000 mg/m2 every 2–3 weeks as a 4–5‐hour IV infusion) and were evaluated for response rate and duration. Hematologic and gastrointestinal toxicity was assessed.

Results: The overall response rate for dogs being treated with DTIC was 35% (14 dogs) with a median progression‐free interval of 43 days. Thirteen dogs had a partial response and 1 dog had a complete response. Stable disease was achieved in 3 dogs. Mild gastrointestinal toxicity was reported in 3 dogs posttreatment. Thrombocytopenia was the principal toxicity observed 7–14 days after the treatment. Treatments were delayed because of thrombocytopenia.

Conclusions: DTIC, when used alone, is effective in the treatment of dogs with relapsed lymphoma.
Tuberculosis Caused by Mycobacterium microti in South American Camelids
Authors: Zanolari P. , Robert N. , Lyashchenko K.P. , Pfyffer G.E. , Greenwald R. , Esfandiari J. , Meylan M.
Published: August 2009

Background: Infection with Mycobacterium microti can cause chronic disease in animals and threaten human health through its zoonotic potential.

Objective: To describe clinical findings, diagnostic investigations, necropsy, and epidemiology results in South American camelids (SAC) infected with M. microti, member of the Mycobacterium tuberculosis complex.

Animals: Eleven SAC with tuberculous lesions.

Methods: Description of 10 llamas and 1 alpaca, aged 4–18 years, from 6 herds with a history of wasting and weakness admitted to the Vetsuisse‐Faculty of Berne over 8 years.

Results: Clinical signs included weight loss, recumbency, and anorexia in late stages of the disease. Respiratory problems were seen in 6 animals of 11. No consistent hematologic abnormalities were identified. Suspect animals were examined in detail by abdominal ultrasonography and thoracic radiology. Abnormal findings such as enlarged mediastinal, mesenteric, or hepatic lymph nodes were seen only in animals with advanced disease. Single comparative intradermal tuberculin test with bovine protein purified derivate (PPD) and avian PPD was negative in all animals. At necropsy, typical tuberculous lesions were found, and confirmed by bacteriological smear and culture, molecular methods, or both.

Conclusions and Clinical Importance: Infection caused by M. microti should be considered a differential diagnosis in chronic debilitating disease with or without respiratory signs in SAC. Antemortem confirmation of the diagnosis remains challenging at any stage of infection. Because cases of M. microti infection have been reported in immunocompromized human patients, the zoonotic potential of the organism should be kept in mind when dealing with this disease in SAC.
Serum Serotonin Concentrations in Dogs with Degenerative Mitral Valve Disease
Authors: Arndt J.W. , Reynolds C.A. , Singletary G.E. , Connolly J.M. , Levy R.J. , Oyama M.A.
Published: August 2009

Background: Increased serotonin (5HT) signaling has been implicated in valvular disease of humans and animals, including canine degenerative mitral valve disease (DMVD). High circulating 5HT concentration is a potential source of increased signaling, and serum 5HT concentrations have not been previously reported in dogs with DMVD.

Hypothesis: Dogs with DMVD and small breed dogs predisposed to DMVD have higher serum 5HT concentrations than large breed controls.

Animals: Fifty dogs affected with DMVD, 34 dogs predisposed to DMVD but without cardiac murmur or echocardiographic evidence of DMVD, and 36 healthy large breed control dogs.

Methods: Prospective analysis. Serum 5HT concentration was measured by an ELISA test.

Results: Median serum 5HT concentration was significantly higher in dogs with DMVD and in dogs predisposed to DMVD as compared with controls (DMVD, 765.5 ng/mL [interquartile range, 561.3–944.4]; predisposed, 774.9 ng/mL [528.3–1,026]; control, 509.8 ng/mL [320.8–708.8]; P= .0001). Subgroup analysis of predisposed dogs indicated significantly higher serum 5HT concentrations in Cavalier King Charles Spaniel (CKCS) dogs than in other breeds (CKCS, 855.0 ng/mL [635.8–1,088]; non‐CKCS, 554.2 ng/mL [380.6–648.4]; P= .0023). Age, platelet count, and platelet morphology were not correlated with 5HT concentration in any group.

Conclusions and Clinical Importance: Dogs with DMVD had significantly higher serum 5HT concentrations when compared with large breed control dogs. Healthy CKCS dogs had significantly higher serum 5HT concentrations than other healthy dogs predisposed to DMVD. Additional investigation into a possible role of 5HT in the pathogenesis of DMVD is warranted.
Enhancing the Homestay: Study Abroad from the Host Family's Perspective
Authors: Knight Susan M. , Schmidt‐Rinehart Barbara C.
Published: August 2009

Abstract: Most foreign language departments encourage their students not only to study abroad, but also to live with host families to maximize linguistic and cultural exposure to the target culture. While there have been a number of studies examining study abroad from the student's and program's perspectives, the native perspective of the homestay experience has been missing. To helpful this void, 24 host families were interviewed in their home settings. The interview data were analyzed using the NUD*IST computer program to determine salient, recurring topics. This article discusses the study design and the major themes that emerged. It concludes with the hosts' recommendations on how students, programs, and the native families themselves can work together to enhance the homestay experience.
The Sanitizing of U.S. Spanish in Academia
Authors: Villa Daniel J.
Published: August 2009

Abstract: The rapidly increasing number of Spanish speakers in the United States has resulted in increased national linguistic tensions. Groups such as U.S. English aim to restrict the use of all non‐English languages in general, and Spanish in particular, in certain public domains. At the same time, another group, which includes a nucleus of language scholars, is engaging in efforts to change or suppress the use of U.S. Spanish, particularly in the domain of education. In this article, the author asserts that the arguments put forward by the latter group are based principally on the attitudes of its leaders and not on carefully constructed linguistic bases. He offers an alternative model, one suggested by Cameron (1995), as a means of carrying out well‐reasoned debate on the use of the Spanish language for academic purposes in the United States.
Active Air Control System to Reduce Two-Stroke Cycle Engine Pollutant Emissions: Validation and Laboratory Testing
Authors: Grauer Diana K. , Chapman Kirby S.
Published: August 2009

This paper presents results from Phase 2 of the development of an Active Air Control (AAC) system to balance air flow into each cylinder of a turbocharged engine system, a PRCI-funded emissions reduction project. Imbalance in air flow creates a discontinuity in trapped equivalence ratio from cylinder to cylinder. Trapped equivalence ratio is directly proportional to NOX production and a function of the fuel flow rate, air flow rate, and, in a two-stroke cycle engine, the scavenging efficiency. Only when these three characteristics are balanced cylinder to cylinder will the combustion and the NOX production in each cylinder be equal. The engine NOX production will be disproportionately high if even one cylinder operates less lean relative to the other cylinders. This paper reports on the testing of an AAC system on a two-cylinder air flow bench at the National Gas Machinery Laboratory at Kansas State University. The results from these tests were then used to further validate the comprehensive, variable geometry, multi-cylinder flow model referred to as the Charge Air Integrated Manifold Engine Numerical Simulation (CAIMENS). CAIMENS is a manifold flow model coupled with the T-RECS engine processor that uses an integrated set of fundamental principles to determine the crank angle-resolved pressure, temperature, burned and unburned mass fractions, and gas exchange rates for the cylinder. CAIMENS has been validated with data from the NGML multi-cylinder flow bench. This information has allowed the research team to (1) quantify the impact of air flow imbalance and (2) provide detailed information leading to the specification of the active air flow control system. The end point of this project is an AAC system that can, with some engineering effort, be applied to field engines.
A Multidimensional Model to Simulate Direct Gaseous Fuel Injection in Internal Combustion Engines
Authors: Andreassi L. , Facci A. L. , Ubertini S.
Published: August 2009

As a consequence of the endless price growing of oil, and oil derivate fuels, automotive industry is experiencing a concerning decreasing in sales. Accordingly, in order to meet customer needs, there is every day a greater interest in solutions for increasing engine efficiency. On the other hand the growing attention to environmental problems leads to increasingly restrictive regulations, such as European EURO 4 and EURO 5. Direct injection of gaseous fuel has emerged to be a high potential strategy to tackle both environmental and fuel economy requirements. However since the electronic gaseous injection technology is rather new for automotive applications, limited experience exists on the optimum configuration of the injection system and the combustion chamber. To facilitate the development of these applications computer models are being developed to simulate gaseous injection, air entrainment and the ensuing combustion. This paper introduces a new method for modelling the injection process of gaseous fuels in multi-dimensional simulations. The proposed model allows holding down grid requirements, thus making it compatible with the three-dimensional simulation of an internal combustion engine. The model is validated and calibrated by comparing numerical results with available experimental data. To highlight the potential applications, some numerical results of the three-dimensional combustion process in a gas engine are presented.
SFC Benefit With Split Injection in Two-Stroke Diesel Engine
Authors: Gokhale Manoj , Tamma Bhaskar , Primus Roy J. , John Benzi
Published: August 2009

The influence of split-injection on engine performance is studied using system and in-cylinder simulation of a two-stroke medium speed diesel engine. System level models for the engine and fuel system and a multi-dimension CFD model for the combustion chamber were developed and calibrated with experimental data. Calibration of these models from the available test data is discussed and calibration results are presented. The SFC and NOx predictions show good sensitivity to injection timing variation. These calibrated models were then used to simulate split injection through the modification of the fuel injector. Split injection achieved through this modification results in fuel savings while maintaining same NOx levels.
Exhaust Emissions and Fuel Consumption of a Railpower RP20BD Switcher Locomotive
Authors: Honc Randell L. , Fritz Steven G. , Osborne Dustin T. , Grisier Richard , Carpenter Scott
Published: August 2009

Conventional switcher or shunting locomotives in North America are powered by a single 12 or 16 cylinder engine which operate at eight distinct power levels, plus idle. Recently introduced locomotive power systems utilize multiple smaller displacement non-road diesel engines packaged as individual generator sets to obtain a cleaner and more efficient locomotive. This paper examines exhaust emissions and fuel consumption of a Railpower RP20BD switcher locomotive utilizing three 375 kWe generators. FTP tests, described in part 92 of the CFR Title 40, were completed for UPY2606 using two fuels: EPA certification diesel, and ultra-low sulfur diesel. The locomotive produced emissions well below EPA Tier 2 limits using certification fuel, and subsequent testing with ULSD further reduced emissions to below the future EPA Tier 2 and 3 limits.
New Charging Model Imparting the Valve Timing for Real-Time Simulation
Authors: Wu Yuh-Yih , Chen Bo-Chiuan , Wu Chieh-Han , Tsai Hsien-Chi
Published: August 2009

Engine Control Units (ECUs) are developed to manage the variable conditions in an operating engine, such as fuel injection, spark ignition, and valve timing, for achieving the goal of high performance, high efficiency and low emissions. Typically, an engine model is necessary for developing the engine control system. Most of the engine models for engine control are mean value engine model (MVEM) based on empirical volumetric efficiency to calculate the intake air flow rate. This kind of model is not able to simulate the changes of the valve, such as valve lift and valve timing. It can not be used for the engine with variable valve train (VVT). Therefore, a new method, able to inform the valve changing, is applied to adapt the new demand of engine models. The proposed engine model is similar to most current models except the charging system. The charging model is developed by using filling-and-emptying model to simulate the air exchange in the engine, including the intake and exhaust air dynamics. The flow through the valves is calculated according to the pressure drop between the cylinder and the manifold, the flow area of the valve opening and its flow coefficient. The other important feature of the proposed engine model is the capability of real time simulation. The model is verified by experimental volumetric efficiency and engine torque. Finally, a HIL (Hardware in the Loop) simulation is performed to confirm the real time simulation.
Combustion Characteristics of HCCI in Motorcycle Engine
Authors: Wu Yuh-Yih , Chen Bo-Liang
Published: August 2009

Homogeneous charge compression ignition (HCCI) is recognized as an advanced combustion system of internal combustion engine for reducing fuel consumption and exhaust emissions. This paper studied a 150 cc air-cooled four-stroke motorcycle engine operating HCCI combustion. The compression ratio was increased from 10.5 to 12.4 by modifying the cylinder head. The kerosene fuel was used without intake air heating and operated at various excess air ratios (λ), engine speeds, and EGR rates. The combustion characteristics and emissions on the target engine were measured. It was found that keeping the cylinder head temperature at around 120–130°C is important for stable experiment. Two-stage ignition was observed from the heat release rate curve, which was calculated from the cylinder pressure. Higher first stage ignition temperature causes higher peak cylinder gas temperature. Higher λ or EGR causes lower peak pressure, lower maximum rate of pressure rise (MRPR), and higher emission CO. However, EGR is better than excess air for decreasing the peak pressure and MRPR without deteriorating the engine output.
Investigation of In-Cylinder Mixing Using Large Eddy Simulation Models for LTC Diesel Applications
Authors: Banerjee Siddhartha , Bharadwaj Nidheesh , Rutland Christopher J.
Published: August 2009

In-cylinder mixture preparation and early combustion heat release are studied using Large Eddy Simulation (LES) for direct injection (DI) diesel with high exhaust gas recirculation (EGR) and early injection timing. Both LES and traditional Reynolds Average Navier-Stokes (RANS) calculations are carried out using KIVA-3V release 2 and compared with experimental results of medium load LTC-diesel (Low Temperature Combustion) cases. Simulations presented in this paper are carried out using KH-RT (Kelvin Helmholtz – Rayleigh Taylor) breakup model for spray atomization and CHEMKIN n-heptane mechanism for combustion and both dynamic structure LES and RNG (re-normalized group) kε RANS for turbulence model. Although engine simulation using LES model poses significant challenges on practical engine grids, significant agreement with LTC-diesel experiments is observed by using an additional spray source term for modeling the effect of liquid sprays on sub-grid kinetic energy transport calculation in engines. Results when compared to RANS, demonstrate that LES is able to predict local spots of early heat release resulting in more accurate prediction of start of combustion timing and early heat release phasing. Mixing due to bulk fluid motion such as swirl is also observed more distinctively in LES calculations.
High-Speed X-Ray Imaging of Diesel Injector Needle Motion
Authors: Kastengren A. L. , Powell C. F. , Liu Z. , Fezzaa K. , Wang J.
Published: August 2009

Phase-enhanced x-ray imaging has been used to examine the geometry and dynamics of four diesel injector nozzles. The technique uses a high-speed camera, which allows the dynamics of individual injection events to be observed in real time and compared. Moreover, data has been obtained for the nozzles from two different viewing angles, allowing for the full three-dimensional motions of the needle to be examined. This technique allows the needle motion to be determined in situ at the needle seat and requires no modifications to the injector hardware, unlike conventional techniques. Measurements of the nozzle geometry have allowed the average nozzle diameter, degree of convergence or divergence, and the degree of rounding at the nozzle inlet to be examined. Measurements of the needle lift have shown that the lift behavior of all four nozzles consists of a linear increase in needle lift with respect to time until the needle reaches full lift and a linear decrease as the needle closes. For all four nozzles, the needle position oscillates at full lift with a period of 170–180 μs. The full-lift position of the needle changes as the rail pressure increases, perhaps reflecting compression of the injector components. Significant lateral motions were seen in the two single-hole nozzles, with the needle motion perpendicular to the injector axis resembling a circular motion for one nozzle and linear oscillation for the other nozzle. The two VCO multihole nozzles show much less lateral motion, with no strong oscillations visible.
Tri-Axial Force Measurements on the Cylinder of a Motored SI Engine Operated on Lubricants of Differing Viscosity
Authors: O’Rourke Bryan , Radford Donald , Stanglmaier Rudolf
Published: August 2009

Friction is a determining factor in the efficiency and performance of internal combustion engines. Losses in the form of friction work typically account for 10–20% of an engine’s output. Improvements in the friction characteristics of the power cylinder assembly are essential for reducing total engine friction and improving the mechanical efficiency of internal combustion engines. This paper describes the development and implementation of a new concept of the ‘floating liner’ engine at Colorado State University that allows 0.5 crank angle degree resolved measurement of the forces on the cylinder along 3 axes — in the axial direction, the thrust direction, and along the wrist pin. Three different lubricants with differing properties were tested to observe the friction characteristics of each. Experimental results showed that the floating liner engine was able to resolve changes in friction characteristics coinciding with changes in lubricant viscosity and temperature. Axial force increases at TDC and BDC were observed as lubricant viscosity was decreased and larger amounts of mixed and boundary lubrication began to occur. For each test the axial friction force data was used to calculate total cycle friction work. The thrust and off-axis (wrist pin direction) forces are discussed under the same circumstances.
Low End Performance Improvement by Effective Use of Multiple Injection Strategy in Common Rail Diesel Engine
Authors: Hareendranath Dilunath , Gajarlawar Nilesh , Manickam Murali , Pundlik Ghodke
Published: August 2009

Main advantages of diesel engine are low fuel consumption coupled with high specific power output. However, benchmark Noise, Vibration and Harshness (NVH) of its counterpart (Gasoline), future stringent emission norms and overall system cost poses tough challenges. In a growing market like India, these benefits of diesel attract the buyer over its counterpart. Diesel engines are known for its heavy visible black smoke. The black smoke formation is more prominent in lower engine speed. This is due to lower injection pressure and the system limitation in conventional injection system and less air availability. Introduction of the common rail injection technology overcomes this difficulty by allowing the injection pressure to build irrespective of the engine speed. However, improving the air flow is a challenge. Generally waste gate turbo chargers are optimized for higher engine speed to match the rated engine performance, but compromising the lower engine speed performance. The use of Variable Geometry turbo charging (VGT), increase in number of valves per cylinder, two stage turbo charging are some of the solutions to this problem but it involves additional cost and fundamental design changes. Hence, it was a challenge to come up with a strategy to overcome this problem without any cost impact. Multiple injection strategy is one of the tools which improve the engine torque without the penalty of smoke. In this paper, a Multi Utility Vehicle (MUV) powered by a 2.5Ldiesel common rail engine, low end performance was effectively improved by this strategy. Current engine has BOSCH 2nd generation common rail system with waste gate Turbocharger. Torque at full load in lower engine speed was improved by introducing the early pilot with relatively higher quantity. However, in the part load, this pilot quantity was split into two successive pilot injections. Selection of pilot separation was optimized in such a way that Noise and Smoke levels are maintained or improved. In part load, improvement in smoke and BSFC was achieved without sacrificing noise level. Engine level trials were conducted with cylinder pressure and Noise Measurement with AVL Indicom. The Concept of Design of experiment (DOE) was used to minimize the number of iteration and for analysis of results. The vehicle performance, pass by noise were found to be improved.
Reduction of NOx and CO Emissions in Stoichiometric Diesel Combustion Using a 3-Way Catalyst
Authors: Kim Junghwan , Reitz Rolf D. , Park Sung Wook , Sung Kian
Published: August 2009

Experimental and numerical studies were performed to investigate the simultaneous reduction of NOx and CO for stoichiometric diesel combustion with a 3-way catalyst. A single-cylinder engine was used for the experiments and KIVA simulations were used in order to characterize the combustion efficiency and emissions of throttled stoichiometric diesel combustion at 0.7 bar boost pressure and 90MPa injection pressure. In addition, the efficiency of emission conversion with the 3-way catalysts in stoichiometric diesel combustion was investigated experimentally. The results showed CO and NOx emissions can be controlled with the 3-way catalyst in spite of the fact that CO increases more at high equivalence ratios compared to conventional diesel combustion (i.e., lean combustion). At stoichiometric operation, the 3-way catalyst reduced CO and NOx emissions by up to 95%, which achieves lower emissions compared to conventional diesel combustion or low temperature diesel combustion, while keeping better fuel consumption than a comparable gasoline engine.
Robust Design of a Large Industrial Natural Gas Engine Piston
Authors: Donahue Richard J. , Draeger William A. , Schaefer Nathan P.
Published: August 2009

Dresser Waukesha has developed a more robust piston capable of operating under abuse conditions beyond those typically seen for large industrial natural gas engines. The results of the modeling and experimental work used to develop and validate the new robust piston will be presented in this paper. Simulation tools were first used to gain a comprehensive understanding of the causes of piston scuffing when operated under abuse conditions. With this understanding, an improved design was developed and the design changes were compared to the original piston. The performance of the new design was then simulated and compared to the original design. To investigate the robustness of the new design, the effect of reducing the major diameter clearance beyond the print specification was studied. Wear loads were predicted to be insensitive to size variations and were predicted to be acceptable even to the limit of a cold piston/liner interference fit. The predicted robustness of the new design was confirmed with experimental testing.
Effect of the Spray-Atomization Characteristics on the Nano Size Particle Exhaust Emissions Characteristics Using Biodiesel-Bioethanol Blended Fuels in a DI Diesel Engine With Common Rail Injection System
Authors: Park Su Han , Yoon Seung Hyun , Kim Hyung Jun , Lee Chang Sik
Published: August 2009

The purpose of this work is to investigate the spray-atomization, combustion and emissions characteristics of biodiesel-bioethanol (BE) and biodiesel-diesel (BD) blended fuels compared with an undiluted biodiesel fuel. For studying the overall spray characteristics, the spray tip penetration, spray cone angle were analyzed from the spray images, and droplet size and distribution were analyzed from the droplet measuring system. In addition, the combustion and exhaust emissions characteristics including the nano-size particle number and size distribution of particulate matter were studied using the direct injection diesel engine with a single cylinder. In this investigation, it revealed that BE and BD blended fuels have slightly higher spray tip penetration and wider spray cone angle due to the reduction of fuel properties such as fuel density and kinematic viscosity. Fuel droplet sizes of blended fuels were distributed in the region of the lower diameter size, compared to biodiesel fuel. It can be said that the reduced fuel viscosity and surface tension of blended fuels affect the atomization performance of biodiesel fuel. The experimental results of spray characteristics were compared with the predicted results through the numerical method by the KIVA-3V. On the other hand, BD blended fuel has a similar combustion and emission characteristics compared with an undiluted biodiesel fuel. In case of BE blended fuel, the ignition delay becomes longer and the rate of heat release becomes high. In the case of exhaust emission characteristics of BE blended fuel, it has lower soot emission, contrary to the almost same nitrogen oxides, hydrocarbon, and carbon monoxide. In the analysis of particle size and number distribution, the number and size distribution of B100 and BD20 fuels have a similar pattern and value. However, BE blended fuel has a lowest particle number in the region of nuclei mode. Moreover, the increase of the injection pressure affects the increase of the smaller size particle of BE blended fuel.
Effect of Injection Strategy on the Combustion and Exhaust Emissions Characteristics of Biodiesel-Ethanol Blend in a DI Diesel Engine
Authors: Yoon Seung Hyun , Hwang Jin Woo , Suh Hyun Kyu , Lee Chang Sik
Published: August 2009

An experimental investigation was performed on the effect of injection strategy on the combustion, exhaust emissions characteristics and the particle size distribution in a direct-injection (DI) compression ignition engine fueled with biodiesel-ethanol blended fuel. The results obtained from the experiment of the particle distributions for the blended fuel are compared to that of diesel fuel. In addition to the distribution of the particles, exhaust emissions such as oxides of nitrogen (NOx), hydrocarbon (HC), and carbon monoxide (CO) emissions and combustion characteristics under different engine operating parameters were investigated. The engine operating parameters in terms of injection timing and injection strategy were varied to investigate the combustion and emission reduction of biodiesel and ethanol blended fuel. The results show that multiple injection strategy of biodiesel-ethanol blended is beneficial to reduce NOx emissions significantly without significant increase of soot emission. In multiple injection strategy, as the first injection mass was increased, the larger size particles were increased, however total numbers of particles were reduced. Biodiesel-ethanol blended fuel reduced particle concentration of relatively large size compared to the particles concentration of ULSD. Moreover, dramatically lower NOx and soot emissions were found at the blend fueled with engine at the same injection condition.
Analysis of Throttle Opening Variation Impact on a Diesel Engine Performance Using Second Law of Thermodynamics
Authors: Sahoo B. B. , Saha U. K. , Sahoo N. , Prusty P.
Published: August 2009

The fuel efficiency of a modern diesel engine has decreased due to the recent revisions to emission standards. For an engine fuel economy, the engine speed is to be optimum for an exact throttle opening (TO) position. This work presents an analysis of throttle opening variation impact on a multi-cylinder, direct injection diesel engine with the aid of Second Law of thermodynamics. For this purpose, the engine is run for different throttle openings with several load and speed variations. At a steady engine loading condition, variation in the throttle openings has resulted in different engine speeds. The Second Law analysis, also called ‘Exergy’ analysis, is performed for these different engine speeds at their throttle positions. The Second Law analysis includes brake work, coolant heat transfer, exhaust losses, exergy efficiency, and airfuel ratio. The availability analysis is performed for 70%, 80%, and 90% loads of engine maximum power condition with 50%, 75%, and 100% TO variations. The data are recorded using a computerized engine test unit. Results indicate that the optimum engine operating conditions for 70%, 80% and 90% engine loads are 2000 rpm at 50% TO, 2300 rpm at 75% TO and 3250 rpm at 100% TO respectively.
A Study on an Automatically Variable Intake Exhaust Injection Timing Turbo-Charging System for Diesel Engines
Authors: Yang Shiyou , Deng Kangyao , Cui Yi , Gu Hongzhong
Published: August 2009

A new turbo-charging system, named AVIEIT (automatically variable intake exhaust injection timing), is proposed. Its main purpose is to improve the performance of low speed high torque operating conditions and improve the economy of high speed operating conditions for high-speed supercharged inter-cooled diesel engines. The principle of the AVIEIT turbo-charging system is presented. A control mechanism for the proposed AVIEIT system used for a truck diesel engine is introduced. An engine simulation code has been developed. In this code, zero-dimensional in-cylinder combustion model, one-dimensional FVM-TVD (finite volume method-total variation diminishing) model for unsteady gas flow in the intake and exhaust manifold, and turbocharger model are used. The developed code is used to simulate the performances of diesel engines using the AVIEIT system. Simulations of a military use diesel engine “12V150” and a truck diesel engine “D6114” using the AVIEIT system have been performed. Simulation results show that the in-cylinder charge air amount of the diesel engine with the AVIEIT system is increased at low speed high torque operating conditions, and the fuel economy is improved at high speed operating conditions. In order to test the idea of the AVIEIT system, an experiment on a truck diesel engine “D6114” equipped with an AVIEIT control mechanism has been finished. The experiment results show that the AVIEIT system can improve economy of high speed operating conditions. Both the simulation and experiment results suggest that the AVIEIT system has the potential to replace the Waste-Gate and VGT turbo-charging systems.
Biodiesel Fuel’s Effects on Influencing Parameters of Brake Fuel Conversion Efficiency in a Medium Duty Diesel Engine
Authors: Bittle Joshua A. , Younger Jesse K. , Jacobs Timothy J.
Published: August 2009

Biodiesel remains an alternative fuel of interest for use in diesel engines. A common characteristic of biodiesel, relative to petroleum diesel, is a lowered heating value (or per mass energy content of the fuel). For same-torque engine comparisons, the lower heating value translates into a higher brake specific fuel consumption (amount of fuel consumed per unit of power produced). The efficiency at which fuel energy converts into work energy, however, may remain unchanged. In this experimental study, evaluating nine unique engine operating conditions, brake fuel conversion efficiency (an assessor of fuel energy to work energy efficiency) remains unchanged between 100% petroleum diesel fuel and 100% biodiesel fuel (palm olein) at all conditions except for high load conditions. Several parameters may affect brake fuel conversion efficiency, including heat loss, mixture properties, pumping work, friction, combustion efficiency, and combustion timing. This article describes a study that evaluates how the aforementioned parameters may change with the use of biodiesel and petroleum diesel, and how these parameters may result in differences in brake fuel conversion efficiency.