bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability Analysis of QFT Controllers Designed for Hydraulic Actuators Using Takagi-Sugeno Fuzzy Modeling Approach
Authors: Esfandiari Masoumeh , Sepehri Nariman
Published: February 2014

Although, robust controllers that have been designed for hydraulic actuators based on quantitative feedback theory (QFT) have shown satisfactory performance, their stability is limited to certain set of inputs-outputs. This paper explores, for the first time, the stability of a QFT controller using stability theorem of Takagi-Sugeno (T-S) fuzzy systems. To do this, first the hydraulic closed-loop system is represented by a T-S fuzzy model that is formed through a nonlinear combination of some local linear models. Next, the stability of the resulting T-S fuzzy system is analyzed simply by stability analysis of its local linear models. This approach is used to study the stability of a QFT position controller previously developed for hydraulic actuators. Results show guaranteed stability of the QFT controller over a wide range of operation and in the presence of parametric uncertainties.
Research on the Stability of a Hydraulic Propulsion System Controlled by Proportional Pressure Reducing Valves
Authors: Zhou Feng , Gu Linyi , Luo Gaosheng , Li Lin , Zheng Mengjun
Published: February 2014

The hydraulic propulsion system is widely used in underwater vehicles due to its high power density and good control performance. In this paper, a torque-controlled hydraulic propulsion system which consists of a pump, a couple of proportional pressure reducing valves and a thruster driven by a hydraulic motor is presented. It has a much lower cost and a higher efficiency compared with servo valve control systems. And its response is still quick enough to control the underwater vehicles’ attitude compared with secondary regulation systems. However, while the propeller is running at a low shaft speed, its load characteristics may lead to instability due to its low load stiffness at low speed, low friction and small internal leakage inside the hydraulic motor.

In this paper, all these hydraulic parameters, even the fluid viscosity and the effective bulk modulus, which may influence its stability, are all analyzed and simulated. Based on this, a drive-pressure and back-pressure independent regulation control method is proposed. Pool experiments shows that this double pressure regulated hydraulic propulsion system is quite stable and reliable at low shaft speed.
Comparative Study on Dynamic Characteristics of Hydraulic, Pneumatic and Electric Motors
Authors: Tanaka Yutaka , Sakama Sayako , Nakano Kazuo , Kosodo Hiroshi
Published: February 2014

Hydraulic or pneumatic motors are replacing electromagnetic servomotors in many applications. It is important for engineers and designers to select adequate actuators in given servo applications. In a previous paper, Nakano had predicted the performance of future electric or hydraulic motors after that there have been many advances in actuators. In this paper the performance of hydraulic and pneumatic motors, and electric AC servo and DC motors has been calculated, surveyed, and evaluated on the basis of specifications listed for them in current catalogs and nonpublic data. We selected 765 different kinds of electric motors and 404 different kinds of fluid power motors available in the market. Power density, torque–inertia ratio, power rate, and power rate density were selected as the performance indexes for comparison. Rated power and torque were found to be nearly proportional to motor mass and moment of inertia, respectively. The electromagnetic motors have developed high performance with large rated torque and a smaller moment of inertia. The newly developed small-size hydraulic motor was also included in the performance index, and its characteristics were plotted. The compact size of fluid power actuators has great potential for power rating or quick response.
Effect of Proportional Valves and Cylinders on the Behavior of Hydraulic Positioning Systems
Authors: Muraro Irving , Teixeira Paulo Leonel , De Negri Victor Juliano
Published: February 2014

Hydraulic positioning control systems are widely employed in several engineering fields such as industry, aerospace, vehicles, and electrical power plants. However, their design is not a straightforward engineering task because several configurations and sizes of valves and cylinders are available, the system components exhibit nonlinear behavior, and the aspects of both fluid mechanics and control theory need to be included for achieving a suitable design. Furthermore, each application has static and dynamic requirements that need to be fulfilled under uncertain loading conditions. Dynamic simulation is an important tool for the analysis and design of hydraulic positioning systems; however, the main characteristics of the components should be known beforehand so that the parameters and model structure can be defined. To overcome these constraints, comprehensive knowledge of the design problem is necessary to ensure appropriate sizing of the hydraulic components. In this regard, this paper presents a detailed study of the influences of the natural frequency and flow coefficient of the valves. The actuator natural frequency is also analyzed, and its modification according to the system requirements is described. The influence of these parameters on the behavior of a closed-loop hydraulic control system with a proportional controller is evaluated using a detailed mathematical model implemented in MATLAB®/Simulink®. Model validation is accomplished using a workbench.
Stability of a Proportional Valve Control System With Backlash and Saturation
Authors: Moustafa Nader , Fales Roger
Published: February 2014

In this work, the describing function technique is used to study the stability of a nonlinear system. All of dynamic systems in industrial and fluid power systems are nonlinear and include uncertainties to some degree. Thus, unexpected changes in the stability can be exhibited and can lead these systems to become unstable or exhibit oscillatory behavior. Engineers have developed nonlinear mathematical models to be able to predict whether or not a designed system will be exposed to such an oscillation before considering building and implementing the system.

The focus of this study is to predict the existence of nonlinear oscillation behavior in a dynamic system using a simplified approach. A nonlinear model validation of a solenoid operated proportional control valve was performed using open loop testes. The type of two-stage hydraulic valve considered in this research is used to control the velocity of hydraulic cylinders. The pilot valve, which is the focus of this research, is a pressure control 3-way valve. A number of 30 replications of this pilot spool valve were studied and tested experimentally along with a single main stage valve. The model consists of linear and nonlinear parts. The linear part of the model was developed by linearizing the nonlinear governing equations at nominal conditions. The nonlinear part was constructed by analyzing open loop experimental test data. The data showed that two major nonlinearities are found that are key to describing the behavior of the system: saturation of the current input and backlash hysteresis behavior. These nonlinearities were considered to be the cause of limit cycle behavior. Each one of these nonlinearities was represented by its describing function and limit cycles were predicted using the describing function analysis method. In using the describing function method, the complexities of working with the nonlinear physics based model to determine limit cycle behavior were avoided.
RANS and LES of IC Engine Flows: A Comparative Study
Authors: Yang Xiaofeng , Gupta Saurabh , Kuo Tang-Wei , Gopalakrishnan Venkatesh
Published: February 2014

A comparative cold flow analysis between Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) cycle-averaged velocity and turbulence predictions is carried out for a single cylinder engine with transparent combustion chamber (TCC) under motored conditions using high-speed Particle Image Velocimetry (PIV) measurements as the reference data. Simulations are done using a commercial CFD code CONVERGE with the implementation of standard k-ε and RNG k-ε turbulent models for RANS and a one-equation eddy viscosity model for LES. The following aspects are analyzed in this study:

1. The effects of computational domain geometry (with or without intake and exhaust plenums) on mean flow and turbulence predictions for both LES and RANS simulations

2. Comparison of LES versus RANS simulations in terms of their capability to predict mean flow and turbulence

Both RANS and LES full and partial geometry simulations are able to capture the overall mean flow trends qualitatively; but the intake jet structure, velocity magnitudes, turbulence magnitudes and its distribution are more accurately predicted by full geometry simulations.

The guideline therefore for CFD engineers is that RANS partial geometry simulations (computationally least expensive) are good enough for capturing overall qualitative flow trends. However, if one is interested in getting reasonably accurate estimates of velocity magnitudes, flow structures, turbulence magnitudes and its distribution, they must resort to LES simulations. Furthermore, to get the most accurate turbulence distributions, one must consider running LES full geometry simulations.
Simulation of Jet Impingement Heat Transfer
Authors: Nasif G. , Barron R. M. , Balachandar R. , Iqbal O.
Published: February 2014

A numerical investigation to determine flow and thermal characteristics of an unsubmerged axisymmetric oil jet impinging on a confined flat surface with uniform heat flux has been undertaken. Large impingement length to nozzle diameter ratios were chosen in the simulations. The volume of fluid (VOF) method utilizing a High Resolution Interface Capturing scheme (HRIC) was used to perform the two-phase (air-oil) simulations. The governing 3D Navier-Stokes equations and energy equation were numerically solved using a finite volume discretization on an unstructured mesh. A new methodology was developed to define the radial extent of the stagnation region and understand the variation of the heat transfer coefficient in this region. The normalized local Nusselt number profile was found to be slightly dependent on Reynolds number for a given nozzle size. Correlations to predict the dimensionless velocity gradient and the Nusselt number in the stagnation region were established.
Optical Investigation of the Effects of Ethanol/Gasoline Blends on Spark-Assisted HCCI
Authors: Fatouraie Mohammad , Wooldridge Margaret S.
Published: February 2014

Spark assist (SA) has been demonstrated to extend the operating limits of homogeneous charge compression ignition (HCCI) modes of engine operation. This experimental investigation focuses on the effects of 100% indolene and 70% indolene/30% ethanol blends on the ignition and combustion properties during SA HCCI operation. The spark assist effects are compared to baseline HCCI operation for each blend by varying spark timing at different fuel/air equivalence ratios ranging from ϕ = 0.4–0.5. High speed imaging is used to understand connections between spark initiated flame propagation and heat release rates. Ethanol generally improves engine performance with higher IMEPn and higher stability compared to 100% indolene. SA advances phasing within a range of ∼5 CAD at lower engine speeds (700 RPM) and ∼11 CAD at higher engine speeds (1200 RPM). SA does not affect heat release rates until immediately (within ∼5 CAD) prior to autoignition. Unlike previous SA HCCI studies of indolene fuel in the same engine, flames were not observed for all SA conditions.
Computational Analysis of a Diesel Engine Autoignition, Combustion, and Emissions Using Injection Rate Shapes
Authors: Shrestha Amit , Zheng Ziliang , Badawy Tamer , Henein Naeim A.
Published: February 2014

Injection rate shaping is a method used to control the instantaneous mass flow rate of the fuel during an injection event. The rate at which the fuel is delivered affects the composition of the combustible mixture and its distribution in the combustion chamber, thereby has an impact on the combustion process in the diesel engine. This paper investigates the effects of five different types of injection rate shapes on diesel engine autoignition, combustion, and engine-out emission trends using a three-dimensional computational simulation approach. For this purpose, an n-heptane fuel model is utilized. Initially, a tophat rate-shape, characterized by the constant mass flow rate of the fuel, is assumed to represent the actual injection profile of an actual engine. Then, in order to develop sufficient confidence in the simulation predictions, this assumption together with the calibrated CFD models are validated by reproducing the cylinder gas pressure, the rate of heat release, and engine-out emissions trends for two sets of engine operating conditions. Later, using all the rate shapes the investigation is conducted for one test point considering two different cases of fuel injection: Case 1 - same SOI and duration of injection (DOI), and Case 2 - same combustion phasing and DOI.

The results obtained from the computational analysis show that the injection rate shape affects the autoignition, combustion, and emissions of a diesel engine. It is observed that the rate shapes, characterized by high injection rates at the beginning of the injection event, enhance the formation of negative temperature coefficient (NTC) regime. Therefore, the mole fractions of different species are determined during the NTC regime in order to examine the processes relevant to the formation of the NTC regimes for these rate shapes. Further, for the same SOI and DOI case, significant differences in the ignition delays between each rate shapes are observed. The maximum deviation of the ignition delay from the reference tophat is found to be 37%. Furthermore, the paper highlights the differences in the cylinder gas pressure, gas temperature, and rate of heat release due to different fuel delivery rates of different rate shapes. Finally, the comparison of the engine-out emissions for different rate shapes for both the cases of injection are presented and discussed in detail.
Simultaneous High-Speed Imaging of Fuel Spray, Combustion Luminosity, and Soot Luminosity in a Spray-Guided Direct Injection Engine With Different Multi-Hole Fuel Injectors
Authors: Zhang Ming , Drake Michael C. , Peterson Kevin
Published: February 2014

Eight different multi-hole fuel injectors with nominally the same exterior geometry (8-hole, 60 degree circular symmetric spray pattern) but different levels of development (Generation I and Generation II), length-to-diameter (L/D) ratios (1.4 to 2.4), and manufacturing processes (EDM vs. laser drilled) are compared in a spray-guided, spark-ignition direct injection (SG-SIDI) single-cylinder optical engine. In-cylinder pressure measurements and exhaust emission measurements quantified effects of different injectors on combustion and emissions. Crank-angle-resolved white-light spray imaging and simultaneous flame and soot visualization quantified variations in spray structure, combustion propagation, and soot formation and oxidation.

At a single operating condition (2000rpm, 95kPa inlet pressure, 90°C engine temperature, end of injection timing (EOI) @ 36 BTDC, spark advance (SA) @ 36 BTDC, 8.1mg/injection), all eight injectors have nearly the same IMEP (about 270kPa) and engine-out gaseous emissions. Experiments show that laser drilled injectors with lower L/D ratios (L/D = 1.4–2.0) have a totally collapsed fuel spray structure, a more penetrating liquid spray with severe fuel impingement on the piston, and rapidly-forming soot deposits on the piston. The collapsed, more compact fuel spray vaporized more slowly and the resulting rich zones led to strong soot luminosity. In contrast, the laser drilled injector with the highest L/D ratio (2.4) and the two EDM injectors (Generation I and Generation II with L/D = 2.0) show 8 distinct spray plumes, less fuel impingement, and much less soot emission intensity. Image analysis tools developed in Matlab were used to characterize the flame propagation and soot formation processes.
Predicting Droplet Size and Spray Angle of a Fuel Spray From an Automobile Fuel Injector With Multi-Swirl Nozzles
Authors: Yoshimura Kazuki , Ishii Eiji , Okamoto Yoshio , Kobayashi Nobuaki
Published: February 2014

A fuel injector with multi-swirl nozzles for finely atomizing a fuel spray in a gasoline engine was developed. The multi-swirl nozzles are composed of swirl chambers placed in the upstream of each orifice which is an outlet of injector. The swirl flow produced by the swirl chambers forms thin liquid films on the walls of the orifices by centrifugal force, and these films break up into small droplets outside the orifices. In this study, fuel flow within the swirl nozzle was simulated by using the volume of fluid (VOF) method, and the simulated velocities and width of the thin liquid film were used to predict the droplet size and spray angle of the fuel spray. Miyamoto’s atomization model was applied to connect a circumferential velocity and a width of the liquid film at the orifice outlet with the droplet size. It was found that the droplet size and spray angle of multi-swirl nozzles can be predicted by using the VOF method and Miyamoto’s atomization model.
Large Eddy Simulation of Vaporizing Sprays Considering Multi-Injection Averaging and Grid-Convergent Mesh Resolution
Authors: Senecal P. K. , Pomraning E. , Xue Q. , Som S. , Banerjee S. , Hu B. , Liu K. , Deur J. M.
Published: February 2014

A state-of-the-art spray modeling methodology, recently presented by Senecal et al. [1, 2], is applied to Large Eddy Simulations (LES) of vaporizing sprays. Simulations of non-combusting Spray A (n-dodecane fuel) from the Engine Combustion Network are performed. An Adaptive Mesh Refinement (AMR) cell size of 0.0625 mm is utilized based on the accuracy/runtime tradeoff demonstrated by Senecal et al. [2]. In that work it was shown that grid convergence of key parameters for non-evaporating and evaporating sprays was achieved for cell sizes between 0.0625 and 0.125 mm using the Dynamic Structure LES model.

The current work presents an extended and more thorough investigation of Spray A using multi-dimensional spray modeling and the Dynamic Structure LES model. Twenty different realizations are simulated by changing the random number seed used in the spray sub-models. Multi-realization (ensemble) averaging is shown to be necessary when comparing to local spray measurements of quantities such as mixture fraction and gas-phase velocity. Through a detailed analysis, recommendations are made regarding the minimum number of LES realizations required for accurate prediction of Diesel sprays. Finally, the effect of a spray primary breakup model constant on the results is assessed.
Multi Sensing Fuel Injector in Turbocharged Gasoline Direct Injection Engines
Authors: Estefanous Fadi , Mekhael Shenouda , Badawy Tamer , Henein Naeim , Zahdeh Akram
Published: February 2014

With the increasingly stringent emissions and fuel economy standards, there is a need to develop new advanced in-cylinder sensing techniques to optimize the operation of internal combustion engine. In addition, reducing the number of on-board sensors needed for proper engine monitoring over the life time of the vehicle would reduce the cost and complexity of the electronic system.

This paper presents a new technique to enable one engine component, the fuel injector, to perform multiple sensing tasks in addition to its primary task of delivering the fuel into the cylinder. The injector is instrumented within an electric circuit to produce a signal indicative of some injection and combustion parameters in electronically controlled spark ignition direct injection (SIDI) engines. The output of the multi sensing fuel injector (MSFI) system can be used as a feedback signal to the engine control unit (ECU) for injection timing control and diagnosis of the injection and combustion processes. A comparison between sensing capabilities of the multi-sensing fuel injector and the spark plug-ion sensor under different engine operating conditions is also included in this study. In addition, the combined use of the ion current signals produced by the MSFI and the spark plug for combustion sensing and control is demonstrated.
Comparison of Different Chemical Kinetic Models for Biodiesel Combustion
Authors: Som S. , Wang Z. , Liu W. , Longman D. E.
Published: February 2014

The current study compares the predictions by four different published mechanisms in literature which have been used for 3 dimensional compression ignition engine simulations. These four mechanisms use two different sets of surrogates: (a) methyl decanoate, methyl 9-decenoate, and n-heptane, (b) methyl butanoate and n-heptane. The mechanisms include: (1) 115 species and 460 reactions [1] using surrogate mixture (a); (2) 77 species and 209 reactions [2] using surrogate mixture (a); (3) 145 species and 869 reactions [3] using surrogate mixture (b); (4) 41 species and 150 reactions [4] using surrogate mixture (b). The different reduction techniques implemented to obtain the reduced mechanisms from the detailed mechanisms are briefly described. The surrogate mixture compositions are then modified to match the cetane number of the real biodiesel fuels. The experimental data for comparison include jet-stirred reactor data for species concentrations for biodiesel derived from rapeseed oil and 3 dimensional constant volume combustion data (for ignition, combustion, and emission characteristics), engine data (for pressure, heat release rate, and emission characteristics) for soy-derived biodiesel. 0-D and 3-D constant volume simulations with all the mechanisms can capture the general experimental trends quite well. Large surrogate models and mechanisms tend to provide better predictions at the expense of increased computational costs. The 115 species and 460 reaction mechanism was observed to perform the best among the mechanisms in predicting the jet-stirred reactor and 3-D constant volume data. It was observed that all the mechanisms are able to qualitatively capture the engine performance and emission characteristics.
Grey-Box Modeling for HCCI Engine Control
Authors: Bidarvatan M. , Shahbakhti M.
Published: February 2014

High fidelity models that balance accuracy and computation load are essential for real-time model-based control of Homogeneous Charge Compression Ignition (HCCI) engines. Grey-box modeling offers an effective technique to obtain desirable HCCI control models. In this paper, a physical HCCI engine model is combined with two feed-forward artificial neural networks models to form a serial architecture grey-box model. The resulting model can predict three major HCCI engine control outputs including combustion phasing, Indicated Mean Effective Pressure (IMEP), and exhaust gas temperature (Texh). The grey-box model is trained and validated with the steady-state and transient experimental data for a large range of HCCI operating conditions. The results indicate the grey-box model significantly improves the predictions from the physical model. For 234 HCCI conditions tested, the grey-box model predicts combustion phasing, IMEP, and Texh with an average error less than 1 crank angle degree, 0.2 bar, and 6 °C respectively. The grey-box model is computationally efficient and it can be used for real-time control application of HCCI engines.
Modular Bearing Designs to Cope With the New Engine Designs Demanding High Performance, Lead Free Solutions and Robustness
Authors: Aufischer Rainer , Walker Rick , Offenbecher Martin , Hager Gunther
Published: February 2014

Engine development, driven by environmental considerations outlined in the different emission regulations, fuel economy and fuel availability in combination with economical boundary conditions, needs new approaches in bearing material and design. Since gas engines are gaining market share and firing pressures increase in Diesel engines in order to fulfill fuel economy a special focus has also been taken to tailor-made bearings for these applications.

This complex task has to consider lining compound material strength and stability under different conditions like oil condition and dilution. Thin overlays with long term wear resistance and mixed friction capabilities as well as robust design for extraordinary events like dirt shock loading or adaptations at the engine start are necessary. To fulfill all these requirements different tasks have to be considered:

1. Bearing lining and steel shell compound to fulfill assembly requirements to combine a safe bearing seat with anti-fretting and high strength with base tribological characteristics

2. Design and use of different layers to compensate weakness of the one layer with the strength of another layer

3. Incorporation of special running conditions and cost reduction approaches in the layer design like polymer coatings for start stop and shaft designs with rougher surface finishes

4. Bearing design incorporating special shapes to cope better with deflections and geometric deficiencies of a special engine design or application

In this publication existing and new lining compound approaches including lead free designs, a variety of different overlays from electroplated, polymer and sputtered ones are briefly described. Additionally it is explained how these layers are combined and how they work together to improve bearing performance. Testing of the bearing components and designs on bearing test rigs with new test conditions considering dirt shock and misalignment and their confirmation by engine running experiences are given for a gas engine and a high speed diesel engine applications.

A special outlook on how this approach can be extended to other applications for the sake of robustness, cost reduction or performance increase will summarize the paper.
IC Engine Air System Uni-, Bi-, and Tri-Directional Energy Flow Optimisation: Turbocharging, Turbocompounding and Turbodischarging
Authors: Williams Andy M. , Baker Alan T. , Vijayakumar Ramkumar
Published: February 2014

Air systems are becoming increasingly complex and important for achieving IC engine performance and emission targets. Turbocharging is becoming increasingly prevalent enabling high power density engines, improved pumping work and improved fuel economy. Turbo-compounding allows turbine energy to contribute directly to crankshaft work with the aim of improving fuel economy. Turbodischarging allows turbine energy to be used to extract exhaust gases from the engine reducing pumping work and residual gas fraction while simultaneously increasing the amount of energy that can be recovered by the turbine(s). The optimum energy flow split between turbocharging, turbodischarging and turbocompounding has not previously been explored. This paper presents results of a study investigating the potential of tri-directional energy flow optimisation in comparison to uni-directional optimisation and bi-directional optimisation (i.e. using all three approaches, any two approaches or turbocharging alone).

Thermodynamic analysis demonstrates the potential of bi-directional optimisation to achieve realistically 4% fuel consumption benefit for both turbocharging and discharging, and turbocharging and compounding on gasoline engines from pumping work alone. The peak benefit of the former occurs at a slightly lower engine torque than the latter as the energy cost of a unit fuel consumption benefit with turbodischarging increases with increasing levels of exhaust depressurisation. The Tri-directional optimisation shows a complex optimum position utilising all three systems and achieving a realistic peak benefit of 4.4% fuel consumption improvement. Optimisation on diesel engine architectures suggests significantly lower potential in the order of 1% benefit while lean burn gas engines showed up to 2.6% benefit. Sensitivity to compression and expansion efficiencies, exhaust manifold volume and system temperatures are presented.

The future hybridisation of IC engine air systems may enable energy storage. This paper offers fundamental insight into the marginal fuel cost of capturing energy from the three systems and the marginal fuel value of using stored energy in the air system.
Development of a NOx Sensor Minimization Control Algorithm for Control of Gas Engines With NSCR
Authors: Gattoni John M. , Olsen Daniel B.
Published: February 2014

High exhaust emissions reduction efficiencies from a spark ignited (SI) internal combustion engine utilizing a Non Selective Catalyst Reduction (NSCR) catalyst system require complex fuel control strategies. The allowable equivalence ratio (Φ) operating range is very narrow where NSCR systems achieve high exhaust emission reduction efficiencies of multiple species. Current fuel control technologies utilizing lambda sensor feedback for natural gas spark ignited engines are reported to be unable to sustain these demands for extended operation periods and when transients are introduced. Lambda sensor accuracy is the critical issue with current fuel controllers. The goal of this project was to develop a minimization control algorithm utilizing an oxides of nitrogen (NOx) sensor installed downstream of the NSCR catalyst system for feedback air/fuel ratio control. Testing was performed on a 100kW rated natural gas Cummins-Onan generator set that was reconfigured to operate utilizing an electronic gas carburetor (EGC2) with lambda sensor feedback and high reduction efficiency NSCR catalyst system. The control algorithm was programmed utilizing a Labview interface that communicated with the electronic gas carburetor where the fuel trim adjustment was physically made. Improvement under steady state operation was observed. The system was also evaluated during load and fuel composition transients.
Comparison of Experimental and Numerical Modeling of Reforming HCCI Combustion
Authors: Keum SeungHwan , Idicheria Cherian A.
Published: February 2014

Homogeneous charge compression ignition (HCCI) engines have high potential to provide better fuel economy with low emissions than conventional spark ignition (SI) engines. In an HCCI engine, combustion phasing strongly depends on the initial temperature and composition. Negative valve overlap (NVO) with reforming has been investigated as combustion phasing control strategy. However, the reforming process is not yet fully understood and further research is necessary to fully utilize the NVO reforming strategy. In this research, optically measured reforming process was modeled by 3D CFD simulation and the results were compared to understand the reforming process better. The optical measurement was carried out with sodium additive to enhance the combustion luminosity. Numerical simulation was carried out with state-of-art spray model with chemical kinetics for ignition and combustion. The chemical reaction mechanism was optimized for modeling the reforming process. It was found that the luminosity from the optical measurement correlates well with the chemical reaction source terms from the simulation.
Cotton Seed FAME Combustion and Emissions Research in a DI Diesel Engine
Authors: Soloiu Valentin , Weaver Jabeous , Ochieng Henry , Duggan Marvin , Davoud Sherwin , Harp Spencer , Molina Gustavo , Vlcek Brian
Published: February 2014

This study investigates the combustion characteristics of cotton seed fatty acid methyl esters (FAME), with C100 (100% cotton seed biodiesel) and C20 (20% cotton seed biodiesel, 80% ultra-low sulfur diesel #2), in a direct injection diesel engine and compares the results with ultra-low sulfur diesel #2 (ULSD#2). The dynamic viscosity of C100 was found to meet the American Society for Testing and Materials (ASTM) standard. The lower heating value obtained for C100 was 37.7 MJ/kg, compared to 42.7 MJ/kg for ULSD#2. ULSD#2 and C100 displayed ignition delays of 9.6 crank angle degrees (CAD) and 7 CAD representing 1.14 ms and 0.83 ms respectively and a combustion time of 4ms (35 CAD) at 1400 rpm and 8 bar indicated mean effective pressure (IMEP) (100% load). The apparent heat release of the tested fuels at 8 bar IMEP showed both a premixed and diffusion phase and produced maximum values of 122 and 209 J/CAD for C100 and ULSD#2 respectively, with a decreasing trend occurring with increase in percentage of FAME. The 50% mass burnt (CA50) for 100% biodiesel was found to be 3 CAD advanced, compared with ULSD#2. The maximum total heat flux rates showed a value of 3.2 MW/m2 for ULSD#2 at 8 bar IMEP with a 6% increase observed for C100. Mechanical efficiency of ULSD#2 was 83% and presented a 5.35% decrease for C100, while the overall efficiency was 36% for ULSD#2 and 33% for C100 at 8 bar IMEP. The nitrogen oxides (NOx) for C100 presented an 11% decrease compared with ULSD#2. Unburned hydrocarbons value (UHC) for ULSD#2 was 2.8 g/kWh at 8 bar IMEP, and improved by 18% for C100. The carbon monoxide (CO) emissions for C100 decreased by 6% when compared to ULSD#2 at 3 bar IMEP but were relatively constant at 8 bar IMEP, presenting a value of 0.82 g/kWh for both fuels. The carbon dioxide (CO2) emissions for C100 increased by 1% compared with ULSD#2, at 3 bar IMEP. The soot value for ULSD#2 was 1.5 g/kWh and presented a 42% decrease for C100 at 8 bar IMEP. The results suggest a very good performance of cotton seed biodiesel, even at very high content of 100%, especially on the emissions side that showed decreasing values for regulated and non-regulated species.
From Propaganda to Product: The Arthurian Legend in Modern Tarot Decks
Authors: Ridley Elmes Melissa
Published: February 2014

In Britain and the United States, the legend of King Arthur has long served as a tool of political propaganda; however, in contemporary tarot decks focusing on Arthuriana, the initially Christian Arthurian legend is reappropriated for a predominantly pagan consumer base. This essay explores the employment of the legend in tarot cards marketed to a New Age and Neopagan audience steeped in the Celto-Arthuriana tradition. A survey of online reviews and discussions by pagan users suggests that using a pagan version of the Arthurian legend to appeal to a broad Neopagan consumer base has met with some success.
“To be an Infidel or an Unbeliever...” Five Wise Men: Edmund Dulac, W. B. Yeats, and The Magi
Authors: Comstock-Skipp Jaimee K.
Published: February 2014

This paper examines the treatment of the Adoration of the Magi in a 1917 painting by Edmund Dulac (1882–1953). By rendering its subject in a Persian painting style and combining Hindu, Muslim, Buddhist, and Christian elements, Dulac correlates East and West, secular and sacred, Christian and non-Christian. Coming in the midst of the First World War, the painting shows a suffering public in England turning to exoticism as a means of escaping a dismal reality. However calm and serene the figures appear, they mask the tension and angst of the outside world. The artwork illuminates the artist’s time period as well as his own intriguing beliefs, influenced by Theosophy, spiritism, esotericism, mysticism, and occultism.
Richard Wagner’s Der Ring des Nibelungen: Medieval, Pagan, Modern
Authors: Cusack Carole M.
Published: February 2014

Richard Wagner’s Der Ring des Nibelungen is a Romantic work that draws on medieval narrative and thematic elements (e.g., the Poetic Edda, the Völsunga Saga, and the Nibelungenlied). Wagner’s cycle is a polyvalent work of art and can be interpreted as exemplifying both secularisation, as the gods of Valhalla give way to humanity, and reenchantment, in that its performance allows the gods of Germanic myth to “live” on stage. This article addresses the issue of reception by looking at Wagner’s medievalism, the modern Heathenry movement and its use of the Pagan past as a source of legitimation, and finally by examining attendance of performances of the Ring as a significant secular ritual activity that engages with Pagan gods and brings them to modern audiences, Heathen and otherwise.
Effect of surface derived hydrocarbon impurities on Ar plasma properties
Authors: Fox-Lyon Nick , Oehrlein Gottlieb S. , Godyak Valery
Published: February 2014

The authors report on Langmuir probe measurements that show that hydrocarbon surfaces in contact with Ar plasma cause changes of electron energy distribution functions due to the flux of hydrogen and carbon atoms released by the surfaces. The authors compare the impact on plasma properties of hydrocarbon species gasified from an etching hydrocarbon surface with injection of gaseous hydrocarbons into Ar plasma. They find that both kinds of hydrocarbon injections decrease electron density and slightly increase electron temperatures of low pressure Ar plasma. For low percentages of impurities (∼1% impurity in Ar plasma explored here), surface-derived hydrocarbon species and gas phase injected hydrocarbon molecules cause similar changes of plasma properties for the same number of hydrocarbon molecules injected into Ar with a decrease in electron density of ∼4%.
An In-depth Pilot Study on Patterns, Destinations, and Purposes of Walking in Hong Kong Older Adults
Authors: Barnett Anthony , Cerin Ester , Cheung Man-chin , Chan Wai-man
Published: February 2014

Walking is a suitable activity for older adults and has physical and mental health benefits. To devise interventions that impact levels of walking it is necessary to first understand the purposes for which people walk and the destinations to which they walk. Using a 7-day diary and accelerometry, this study investigated destinations and purposes of walking in older adult residents of an ultra-dense Asian city. Participants reported an average of 17.1 walking trips per week and total weekly accelerometer/diary determined trip walking time averaged 735 min per week; much higher than reported for older adults in non-Asian settings. The most common destinations were within the neighborhood: parks and streets for recreation walking and shops and eating places for transport-related walking. Errands and eating were the most common purposes for transportation trips. The study results can help inform urban design to encourage walking.
Patient-Oriented and Performance-Based Outcomes After Knee Autologous Chondrocyte Implantation: A Timeline for the First Year of Recovery
Authors: Howard Jennifer S. , Mattacola Carl G. , Mullineaux David R. , English Robert A. , Lattermann Christian
Published: February 2014

Context:

It is well established that autologous chondrocyte implantation (ACI) can require extended recovery postoperatively; however, little information exists to provide clinicians and patients with a timeline for anticipated function during the first year after ACI.

Objective:

To document the recovery of functional performance of activities of daily living after ACI.

Patients:

ACI patients (n = 48, 29 male; 35.1 ± 8.0 y).

Intervention:

All patients completed functional tests (weight-bearing squat, walk-across, sit-to-stand, step-up/over, and forward lunge) using the NeuroCom long force plate (Clackamas, OR) and completed patient-reported outcome measures (International Knee Documentation Committee Subjective Knee Evaluation Form, Lysholm, Western Ontario and McMaster Osteoarthritis Index [WOMAC], and 36-Item Short-Form Health Survey) preoperatively and 3, 6, and 12 mo postoperatively.

Main Outcome Measures:

A covariance pattern model was used to compare performance and self-reported outcome across time and provide a timeline for functional recovery after ACI.

Results:

Participants demonstrated significant improvement in walk-across stride length from baseline (42.0% ± 8.9% height) at 6 (46.8% ± 8.1%) and 12 mo (46.6% ± 7.6%). Weight bearing on the involved limb during squatting at 30°, 60°, and 90° was significantly less at 3 mo than presurgery. Step-up/over time was significantly slower at 3 mo (1.67 ± 0.69 s) than at baseline (1.49 ± 0.33 s), 6 mo (1.51 ± 0.36 s), and 12 mo (1.40 ± 0.26 s). Step-up/over lift-up index was increased from baseline (41.0% ± 11.3% body weight [BW]) at 3 (45.0% ± 11.7% BW), 6 (47.0% ± 11.3% BW), and 12 mo (47.3% ± 11.6% BW). Forward-lunge time was decreased at 3 mo (1.51 ± 0.44 s) compared with baseline (1.39 ± 0.43 s), 6 mo (1.32 ± 0.05 s), and 12 mo (1.27 ± 0.06). Similarly, forward-lunge impact force was decreased at 3 mo (22.2% ± 1.4% BW) compared with baseline (25.4% ± 1.5% BW). The WOMAC demonstrated significant improvements at 3 mo. All patient-reported outcomes were improved from baseline at 6 and 12 mo postsurgery.

Conclusions:

Patients' perceptions of improvements may outpace physical changes in function. Decreased function for at least the first 3 mo after ACI should be anticipated, and improvement in performance of tasks requiring weight-bearing knee flexion, such as squatting, going down stairs, or lunging, may not occur for a year or more after surgery.
Changes in Seismic Anisotropy Shed Light on the Nature of the Gutenberg Discontinuity
Authors: Beghein Caroline , Yuan Kaiqing , Schmerr Nicholas , Xing Zheng
Published: February 2014

G Below Sea

Rheological differences between Earth's lithosphere and asthenosphere help drive plate tectonics. Geophysical analyses repeatedly reveal a seismic Gutenberg (G) discontinuity at 40- to 100-kilometer depth in oceanic plates, although the origin of this boundary remains enigmatic.

Beghein
et al.

(p.
1237
, published online 27 February) found that vertical stratification of anisotropy aligned with the depths of the G discontinuity, but not with the lithosphere-asthenosphere boundary. It appears that the G discontinuity forms when there are geophysical changes in the mantle, such as dehydration beneath mid-ocean ridges.
Highly Multiplexed Subcellular RNA Sequencing in Situ
Authors: Lee Je Hyuk , Daugharthy Evan R. , Scheiman Jonathan , Kalhor Reza , Yang Joyce L. , Ferrante Thomas C. , Terry Richard , Jeanty Sauveur S. F. , Li Chao , Amamoto Ryoji , Peters Derek T. , Turczyk Brian M. , Marblestone Adam H. , Inverso Samuel A. , Bernard Amy , Mali Prashant , Rios Xavier , Aach John , Church George M.
Published: February 2014

Transcripts Visualized in Situ

Despite advances, current methods for single-cell sequencing are unable to resolve transcript location within the cell, so

Lee
et al.

(p.
1360
, published online 27 February) developed a method of fluorescent in situ RNA sequencing (FISSEQ) that works in vivo to show messenger RNA localization within cells. The method amplifies complementary DNA targets by rolling circle amplification, and then in situ cross-linking locks amplicons to produce ample, highly localized templates for three-dimensional sequencing. The technique was tested in fibroblasts to reveal the differences between individual cells during wound repair.
Genome Sequence of the Mucoromycotina Fungus
Umbelopsis isabellina
, an Effective Producer of Lipids
Authors: Takeda Itaru , Tamano Koichi , Yamane Noriko , Ishii Tomoko , Miura Ai , Umemura Myco , Terai Goro , Baker Scott E. , Koike Hideaki , Machida Masayuki
Published: February 2014

Umbelopsis isabellina
is a fungus in the subdivision Mucoromycotina, many members of which have been shown to be oleaginous and have become important organisms for producing oil because of their high level of intracellular lipid accumulation from various feedstocks. The genome sequence of
U. isabellina
NBRC 7884 was determined and annotated, and this information might provide insights into the oleaginous properties of this fungus.
Obesity in pregnancy: a retrospective prevalence-based study on health service utilisation and costs on the NHS
Authors: Morgan Kelly L , Rahman Muhammad A , Macey Steven , Atkinson Mark D , Hill Rebecca A , Khanom Ashrafunnesa , Paranjothy Shantini , Husain Muhammad Jami , Brophy Sinead T
Published: February 2014

Objective

To estimate the direct healthcare cost of being overweight or obese throughout pregnancy to the National Health Service in Wales.

Design

Retrospective prevalence-based study.

Setting

Combined linked anonymised electronic datasets gathered on a cohort of women enrolled on the Growing Up in Wales: Environments for Healthy Living (EHL) study. Women were categorised into two groups: normal body mass index (BMI; n=260) and overweight/obese (BMI>25; n=224).

Participants

484 singleton pregnancies with available health service records and an antenatal BMI.

Primary outcome measure

Total health service utilisation (comprising all general practitioner visits and prescribed medications, inpatient admissions and outpatient visits) and direct healthcare costs for providing these services in the year 2011–2012. Costs are calculated as cost of mother (no infant costs are included) and are related to health service usage throughout pregnancy and 2 months following delivery.

Results

There was a strong association between healthcare usage cost and BMI (p<0.001). Adjusting for maternal age, parity, ethnicity and comorbidity, mean total costs were 23% higher among overweight women (rate ratios (RR) 1.23, 95% CI 1.230 to 1.233) and 37% higher among obese women (RR 1.39, 95% CI 1.38 to 1.39) compared with women with normal weight. Adjusting for smoking, consumption of alcohol, or the presence of any comorbidities did not materially affect the results. The total mean cost estimates were £3546.3 for normal weight, £4244.4 for overweight and £4717.64 for obese women.

Conclusions

Increased health service usage and healthcare costs during pregnancy are associated with increasing maternal BMI; this was apparent across all health services considered within this study. Interventions costing less than £1171.34 per person could be cost-effective if they reduce healthcare usage among obese pregnant women to levels equivalent to that of normal weight women.
Oral administration of herbal medicines for the treatment of otitis media with effusion: protocol for a systematic review
Authors: Kim Yun Hee , Son Mi Ju , Kim Young-Eun , Lee Hye Won , Lee Myeong Soo
Published: February 2014

Introduction

The purpose of this systematic review is to investigate the efficacy of the oral administration of herbal medicines for otitis media with effusion through analysing trial data.

Methods and analysis

Electronic searches of the following 11 databases will be performed: MEDLINE, CINAHL, EMBASE, AMED, the Cochrane CENTRAL, 3 Chinese databases (CNKI, Wangfang Data and VIP Information) and 5 Korean databases (KoreaMed, Research Information Service System, Korea Studies Information System, Oriental Medicine Advanced Searching Integrated System (OASIS) and DBpia). The selection of the studies, data abstraction and validations will be performed independently by two researchers.

Dissemination

The systematic review will be published in a peer-reviewed journal. The review will also be disseminated electronically and in print. The review will be updated to inform and guide healthcare practice and policy.

Trial registration number

PROSPERO 2013: CRD42013005430.