bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Hydrogen-Fueled, Direct-Injected, Two-Stroke, Small-Displacement Engine for Recreational Marine Applications With High Efficiency and Low Emissions
Authors: Oh David , Plante Jean-Sébastien 
Published: July 2013

A hydrogen-fueled two-stroke prototype demonstrator based on a 9.9 horsepower (7.4 kW) production gasoline marine outboard is presented, which, while matching the original engine’s rated power output on hydrogen, achieves a best-point gross indicated thermal efficiency (ITE) of 42.4% at the ICOMIA Mode 4 operating point corresponding to 80% and 71.6% of rated engine speed and torque, respectively. Brake thermal efficiency (BTE) at rated power is 32.3%. Preliminary exhaust gas measurements suggest that the engine could also meet the most stringent CARB 5-Star marine spark-ignition emission standards limiting HC+NOx emissions to 2.5 g/kWh without any after-treatment. Later fuel injection is found to improve thermal efficiency at the expense of increased NOx emissions and, at the extreme, increased cyclic variation. The mechanism for these observations is reasoned to be increasing charge stratification with the later timings.
All these are realized in a cost-effective concept around a proven two-stroke base engine and a low-pressure, direct-injected gaseous hydrogen (LPDI GH2) system, which employs no additional fuel pump and is adapted uniquely from volume production components. This work outlines the pathway — including investigations of several fuel delivery strategies with limited success — leading to the current status including design; modeling with GT-POWER; delivery of lube oil; lubrication issues using hydrogen; and calibration sweeps. Experimental results comprising steady-state dynamometer performance, cylinder pressure traces, NOx emission measurements, as well as heat release analyses, support the reported numbers and the key finding that late fuel injection timing and charge stratification drive the high efficiencies and the NOx trade-off; this is discussed and forms the basis for future work.
High-Pressure Gaseous Injection: A Comprehensive Analysis of Gas Dynamics and Mixing Effects
Authors: Scarcelli Riccardo , Kastengren Alan L. , Powell Christopher F. , Wallner Thomas , Matthias Nicholas S. 
Published: July 2013

While the transportation field is mostly characterized by the use of liquid fuels, gaseous fuels like hydrogen and natural gas have shown high thermal efficiency and low exhaust emissions when used in internal combustion engines (ICEs). In particular, high-pressure direct injection of a gaseous fuel within the cylinder overcomes the loss of volumetric efficiency and allows stratifying the mixture around the spark plug at the ignition time. Direct injection and mixture stratification can extend the lean flammability limit and improve efficiency and emissions of ICEs.
Compared to liquid sprays, the phenomena involved in the evolution of gaseous jets are less complex to understand and model. Nevertheless, the numerical simulation of a high-pressure gas jet is not a simple task. At high injection pressure, immediately downstream of the nozzle exit the flow is supersonic, the gas is under-expanded, and a large series of shocks occurs due to the effect of compressibility. To simulate and capture these phenomena, grid resolution, computational time-step, discretization scheme, and turbulence model need to be properly set.
The research group on hydrogen ICEs at Argonne National Laboratory has been extensively working on validating numerical results on gaseous direct injection and mixture formation against PIV and PLIF data from an optically accessible engine. While a good general agreement was observed, simulations still could not perfectly predict the mixing of fuel with the surrounding air, which sometimes led to significant under-prediction of fuel dispersion. The challenge is to correctly describe the gas dynamic phenomena of under-expanded gas jets. To this aim, x-ray radiography was performed at the Advanced Photon Source (APS) at Argonne to provide high-detail data of the mass distribution within a high-pressure gas jet, with the main focus on the under-expanded region.
In this paper, the numerical simulation of high-pressure (100 bar) injection of argon in a cylindrical chamber is performed using the computational fluid dynamic (CFD) solver Fluent. Numerical results of jet penetration and mass distribution are compared with x-ray data. The simplest nozzle geometry, consisting of one hole with a diameter of 1 mm directed along the injector axis, is chosen as a canonical case for modeling validation. A sector (90°) mesh, with high resolution in the under-expanded region, is used and the assumption of symmetry is made. Results show good agreement between CFD and x-ray data. Gas dynamics and mass distribution within the jet are well predicted by numerical simulations.
Method for Determining Instantaneous Temperature at the Surface of Combustion Chamber Deposits in an HCCI Engine
Authors: Güralp Orgun , Najt Paul , Filipi Zoran S. 
Published: July 2013

Homogeneous charge compression ignition (HCCI) combustion is widely regarded an attractive option for future high efficiency gasoline engines. HCCI combustion permits operation with a highly dilute, well mixed charge, resulting in high thermal efficiency and extremely low NOx and soot emissions, two qualities essential for future propulsion system solutions.
Because HCCI is a thermo-kinetically dominated process, full understanding of how combustion chamber boundary thermal conditions affect the combustion process are crucial. This includes the dynamics of the effective chamber wall surface temperature, as dictated by the formation of combustion chamber deposits (CCD). It has been demonstrated that, due to the combination of CCD thermal properties and the sensitivity of HCCI to wall temperature, the phasing of auto-ignition can vary significantly as CCD coverage in the chamber increases.
In order to better characterize and quantify the influence of CCDs, a numerical methodology has been developed which permits calculation of the crank-angle resolved local temperature profile at the surface of a layer of combustion chamber deposits. This unique predictor-corrector methodology relies on experimental measurement of instantaneous temperature underneath the layer, i.e. at the metal-CCD interface, and known deposit layer thickness. A numerical method for validation of these calculations has also been devised. The resultant crank-angle resolved CCD surface temperature and heat flux profiles both on top and under the CCD layer provide valuable insight into the near wall phenomena, and shed light on the interplay between the dynamics of the heat transfer process and HCCI burn rates.
Electric Vehicle Drivetrain Development in China
Authors: Yuan Yiqing , Wu Guoqiang , He Xiangyan , Song Yanda , Zhang Xuewen 
Published: July 2013

Despite great progress recently made on applications of in-wheel motors in electric vehicles, almost all production or near-production electric vehicles still utilize mechanical speed reduction systems for transferring torque from the traction motor to wheels for the purposes of torque augmentation and speed reduction. These systems in general fall into three categories, i.e. fixed ratio, stepped variable ratio, or continuously variable ratio.
In China, most electric cars retrofitted from internal combustion engine propelled vehicle models use gear reduction systems of a fixed speed ratio, in order to minimize the time to market. Typically a conversion is made to the original 5-speed manual transmission by taking out a few unused gear sets. With the rapid growth in electric vehicle industry, some gearboxes of fixed speed have been engineered and they typically have a layshaft configuration. Most of them still do not come with a “park” gear due to a lack of understanding on customer’s needs. As an exception, a transmission of fixed speed ratio dedicated for electric vehicle applications has been developed at the Electric Vehicle R&D Center, Chinese Academy of Sciences (UCAS).
Among electric vehicles announced by domestic vehicle manufacturers in China, some employ 5-speed manual transmissions (MTs) or automatic transmission (ATs) that typically found in traditional vehicles. From the driving convenience, transmission efficiency, or cost standpoints, these transmissions are, in general, not appropriate for applications in electric vehicles. The “misusage” of these transmissions has often something to do with their availability rather than suitability. A great deal of effort has been put into the research and development of automated mechanical transmissions (AMTs) in China to date. Significant progress has been made to the reduction of shift time, improvement of shift quality, and optimization of the mechanical components.
Continuously variable transmission (CVT) is considered to be an important trend in drivetrain technology. However, the pulley-belt types of CVT commonly seen in traditional vehicles are not proper for electric vehicle applications. An EVT dedicated for electric vehicles is under development at UCAS, in which the power from an electric motor of dual-rotors is coupled by means of a planetary gear set, allowing continuous variable of the output speed.
In summary, the electric vehicle drivetrain technology in China is undergoing rapid advances, which will impact the development of electric vehicle industry at home and abroad.
Processing and Characterization of Novel Bismaleimide-Based Shape Memory Polymer Composites
Authors: Tandon G. P. , Gibson T. , Shumaker J. , Coomer R. , Baur J. , Justice R. S. 
Published: July 2013

In the present study, a series of novel linear polyaspartimide-based silane endcapped (cross-linked) polymers are synthesized using 4-4′ bismaleimidodiphenylmethane, Jeffamine D-400 (BMI-JA-400), and (3-Aminopropyl) trimethoxysilane. To add strength to these systems, the trimethoxysilane moiety is cross-linked with the addition of water to create a thermosetting material with both improved toughness and variable cross-link densities. Thermal analysis is done to evaluate the developed shape-memory polymer (SMP) resin for composite processing feasibility. The solvent content in the resin and thermal stability is monitored using thermogravimetric analysis (TGA) while advanced rheometric expansion system (ARES) with parallel plate geometry is used to measure viscosity variation with temperature.
The resin BMI-JA-400-Si-70/30 is chosen for making the composite based on its viscosity, weight change, and kinetic results. Differential scanning calorimetry (DSC) is performed to determine the cure kinetics including the temperatures at which the cure reaction initiates and completes in order to develop the cure cycle for composite fabrication. The selected SMP resin is hand-impregnated with T-300 plain-weave and T-700 uni-weave carbon fabric. Six-ply composites are successfully fabricated with < 2% void content using both fabric weaves. The thermo-mechanical properties of the SMP resin are measured using dynamic mechanical analysis (DMA). In addition, the shape memory cycle with free recovery is conducted on the SMP resin and composites.
Actuation Behavior in Patterned Magnetorheological Elastomers: Simulation, Experiment, and Modeling
Authors: von Lockette Paris 
Published: July 2013

Magnetorheological elastomers (MREs) are an emerging class of smart materials whose mechanical behavior varies in the presence of a magnetic field. Historically MREs have been comprised of soft-magnetic iron particles in a compliant matrix such as silicone elastomer. Numerous works have experimentally cataloged the MRE effect, or increase in shear stiffness, versus the applied field. Several other researchers have derived constitutive models for the large deformation behavior of MREs. In almost all cases the arrays of embedded particles, and or the particles themselves, are assumed magnetically symmetric with respect to the external magnetic field, i.e. the bulk materials exhibit magnetic symmetry in the given experimental or analytical configuration.
In this work the author presents results of dynamic shear experiments, Lagrangian dynamic analysis, and static shear simulations on MRE material systems that exhibit broken magnetic symmetry. These new materials utilize barium hexaferrite powder as the magnetically anisotropic filler combined with a compliant silicone elastomer matrix. Simulations of representative laminate structures comprised of varied arrays of magnetic particles exhibit novel actuation behaviors including reversible shearing deformation, variable magnetostriction, and most surprisingly, piezomagnetism. Results of dynamic shear experiments and analytical modeling support predicted shearing actuation responses in MREs having broken symmetry and only in those systems.
Application of Shape Memory Alloys in Locking Devices
Authors: Theiß Ralf , Lichte Daniel , Wolf Kai-Dietrich 
Published: July 2013

Networked and automated locking systems are an easy to use and to administer solution for governmental and commercial use, especially in combination with advanced authentication technologies like RFID-based keys. Regardless of the advances of authentication technologies locking systems still use electric motor transmission units, which are controlled by an authentication and control unit. From an economic and an engineering point of view this approach has significant weaknesses. The main issue is the transformation of the rotational movement generated by the motor into a translational movement, which is necessary for locking applications. This leads to the implementation of a complex transmission and an inappropriate and inefficient mode of operation for the used electric motors, inflicting the reliability and increasing the overall cost as well as the required building space of the system. Consequently, there is a need to reduce the complexity and the cost of locking systems by optimizing the actuator and the mechanical components.
An alternative approach for actuators is usable with Shape Memory Alloys (SMA) and the Shape Memory Effect. Components made from SMA can return after a deformation into a pre-trained shape under certain thermal and mechanical conditions. SMA-based components can provide mechanical work as well as high forces while returning to their previous shape. Common SMA-based actuators have the form wire and provide significant pull forces when activated thermally. So it becomes possible to replace conventional electric motors and the necessary transmission with SMA-based wire actuator.
The article provides an overview of the requirements and restrictions for the application of SMA in locking systems, illustrating the issues of existing locking system designs and an approach to overcome their limitations with a system based on SMA. After a short introduction chapter two introduces SMA as an alternative approach for actuators. Chapter three focuses on the main issues of locking systems and explains the requirements for the development of new actuators for locking devices. Chapter 4 describes the conceptual development of an approach for a SMA-based locking system illustrating security issues. The article concludes with a summery and an outlook.
Development of Multi-DOF Active Microvibration Emulator
Authors: Park Geeyong , Lee Dae-Oen , Han Jae-Hung , Goo Nam Seo 
Published: July 2013

Recently, some components and payload systems installed in satellites are exposed to various disturbance sources, such as the reaction wheel assembly, the control moment gyro, coolers, and others. Because there is low damping in space, the continuous microvibration causes the degradation of the performance of various payload systems. Therefore, the development of a practical isolation system that shields against microvibration are very important and the author is on the way to developing the microvibration isolation system for the improvement on the performance of the optical payload. In order to develop appropriate microvibration isolation device for a specific payload, it is necessary to understand vibration characteristics of the main disturbance sources; modeling and analysis of disturbance sources including reaction wheel assembly and control moment gyros have been studied by many researchers. However, there are practical difficulties to obtain and perform an experiment with real flight model (FM) reaction wheel assembly and control moment gyros because of expensive price and security reasons. Generally, the disturbance characteristics of a prototype of the reaction wheel assembly or control moment gyros are significantly different from those of FM ones even when the reaction wheel type, size and wheel speed are the same.
Therefore, in order to facilitate the microvibration isolation experiment during the satellite development process, this paper proposes a microvibration emulator that could generate the real disturbance spectrums of FMs. Note that the disturbance profiles are quite complex, consisting of several higher harmonics, and also changing for varying operational wheel speeds. The disturbance characteristics of FMs are typically measured in advance. First an analytical model for the RWA is presented and the development procedure for the emulator is also described. The performance of the first prototype emulator is demonstrated.
Seizures in patients with high-grade glioma: a serious challenge in the end-of-life phase
Authors: Sizoo Eefje M , Koekkoek Johan A F , Postma Tjeerd J , Heimans Jan J , Pasman H Roeline W , Deliens Luc , Taphoorn Martin J B , Reijneveld Jaap C 
Published: July 2013

BackgroundTo analyse the prevalence of seizures and use of antiepileptic drugs (AEDs) in the end-of-life (EOL) phase of patients with high-grade glioma (HGG) and to identify patient characteristics associated with the occurrence of seizures in the last week of life.MethodsPatients were recruited from a cohort of adults with HGG diagnosed in 2005 and 2006 in three tertiary referral centres for patients with brain tumour. Physicians involved in the EOL care of patients who had HGG and had died were asked to fill in a questionnaire regarding seizures and antiepileptic treatment in the last 3 months and in the last week of life. Data on seizures and use of AEDs before the EOL phase were obtained from medical correspondence and hospital medical charts.ResultsOut of 155 patients who had died, data for 92 patients were eligible for analysis. Twenty-nine percent of these 92 patients had seizures during the last week of life; 33% of patients had a history of seizures and 22% did not. Besides a history of status epilepticus (p=0.047), we identified no other significant risk factors for developing seizures in the last week of life. Seventy percent of all patients used AEDs before the last week of life. In 35% of patients in whom AEDs were tapered, seizures occurred in the last week of life.ConclusionsOur results demonstrate that seizures are a common symptom in patients with HGG during the last week of life and emphasise the importance of adequate AED treatment throughout the EOL phase.
A relação entre escolaridade e uso do computador: aspectos quantitativos de um estudo de caso junto a adultos pouco escolarizados na cidade de São Paulo.
Authors: Silva Nilce da , Azevedo Cleomar , Andrade Márcia Siqueira de 
Published: July 2013

Este artigo trata da relação entre escolaridade e uso do computador. A partir de pesquisa exploratória, com características quantitativas e qualitativas, junto a dois grupos de participantes: G1, constituído por alunos de EJA da cidade de São Paulo, e G2, formado por alunos em situação de supraescolarização no Quebec, obtivemos elementos sobre a temática em questão. Foram aplicados questionários para a caracterização dos sujeitos envolvidos com o objetivo de relacionar a variável escolaridade e o uso do computador. Realizamos intervenções com observação ativa e entrevistas informais junto a G1. A análise dos dados quantitativos coletados indica que a maioria dos alunos de EJA não se sente à vontade ao falar sobre a cibercultura. Apesar de interessados no assunto, declaravam-se envergonhados por ainda não estarem inseridos neste novo cenário. Constatou-se que os participantes do G2 mostram-se familiarizados com o uso do computador para diversos fins, inclusive o da aprendizagem. Conclui-se que o nível de escolaridade interfere diretamente na utilização do computador, tanto na frequência como na forma, uma vez que quanto maior o grau de escolaridade, maior é a confiança na utilização das ferramentas e aplicativos do computador e ainda que tal temática está no cerne do debate acerca da alfabetização de jovens e adultos e da formação de professores desta modalidade de ensino.
Uma brasilidade recém-começada: “O povo brasileiro” de “Darcy Ribeiro”
Authors: Silva Vidal Bezerra da 
Published: July 2013

A presente resenha sobre o livro: "O povo brasileiro" de "Darcy Ribeiro" procura apresentar o quão importante foi a compilação feita pelo "Professor Darci Ribeiro" que teve uma carreira dedicada ao estudo, trabalho de pesquisa e teve uma importante atuação na vida como um homem público. E, no que tange a compreensão de quem somos e para onde vamos "O povo brasileiro" apresenta-nos uma gama de possibilidades. O referido trabalho foi finalizado em seus momentos finais de vida e as questões da identidade brasileira e identidade com o Brasil ainda não estão claras e sobre as quais, nós, educadores, deveríamos nos debruçar antes de adentrarmos a uma sala de aula. Assim, reavivarmos essa obra para termos uma noção de que forma deveríamos tentar atuar em nossas salas de aulas e em nossas vidas é que vislumbramos ao retomarmos a leitura de "O Povo Brasileiro".
Predictive Value of Electrocardiographic T-Wave Morphology Parameters and T-Wave Peak to T-Wave End Interval for Sudden Cardiac Death in the General Population
Authors: Porthan Kimmo , Viitasalo Matti , Toivonen Lauri , Havulinna Aki S. , Jula Antti , Tikkanen Jani T. , Väänänen Heikki , Nieminen Markku S. , Huikuri Heikki V. , Newton-Cheh Christopher , Salomaa Veikko , Oikarinen Lasse 
Published: July 2013

Background—
Previous population studies have found an association between electrocardiographic T-wave morphology parameters and cardiovascular mortality, but their relationship to sudden cardiac death (SCD) is not clear. To our knowledge, there are no follow-up studies assessing the association between electrocardiographic T-wave peak to T-wave end interval (TPE) and SCD. We assessed the predictive value of electrocardiographic T-wave morphology parameters and TPE for SCD in an adult general population sample.

Methods and Results—

A total of 4 T-wave morphology parameters (principal component analysis ratio, T-wave morphology dispersion, total cosine R-to-T, T-wave residuum) as well as TPE were measured from digital standard 12-lead ECGs in 5618 adults (46% men; mean age 50.9±12.5 years) participating in the Finnish population–based Health 2000 Study. After a mean follow-up time of 7.7±1.4 years, 72 SCDs had occurred. In univariable analyses, all T-wave morphology parameters were associated with an increased SCD risk. In multivariable Cox models, T-wave morphology dispersion and total cosine R-to-T remained as predictors of SCD, with T-wave morphology dispersion showing the highest SCD risk (hazard ratio of 1.4 [95% confidence interval 1.1−1.7,
P
=0.001] per 1 SD increase in the log
e
T-wave morphology dispersion). In contrast, TPE was not associated with SCD in univariable or multivariable analyses.

Conclusions—
Electrocardiographic T-wave morphology parameters describing the 3-dimensional shape of the T-wave stratify SCD risk in the general population, but we did not find an association between TPE and SCD.