bluuebunny/crossref_metadata_2025_split huggingface dataset:
System Synthesis and Controller Design of a Novel Pump Controlled Steer-by-Wire System Employing Modern Control Techniques
Authors: Daher N. , Ivantysynova M. 
Published: February 2014

The demand for power steering systems primarily stemmed from the need for providing assistance to operators in achieving their heading directions, especially as transportation vehicles kept growing in size and mass. While the main requirements for the primitive systems were adequate assistance levels and acceptable controllability, today’s requirements are much different. Given the increased awareness and attention to energy efficiency, productivity, and safety, the field for researching alternative technologies is virtually open. Present-day power steering architectures include hydraulic, electric, and electro-hydraulic structures, which vary based on their energy source, energy transmission, and energy management schemes. Hydraulic power steering is plagued with poor energy efficiency mainly due to throttling losses associated with hydraulic control valves. Electric power steering systems offer better energy efficiency with on-demand power supply and result in improved packaging constraints, but suffer from power limitations at larger scales. State-of-the-art electrohydraulic steering systems take advantage of the high power density and efficiency of fluid power, but use electronically controlled valves that still suffer from energy inefficiency.
This paper introduces a novel electro-hydraulic power steering system that utilizes a proven energy-saving technology, pump displacement control (DC), which eliminates throttling losses associated with hydraulic control valves by controlling the displacement of a variable displacement pump. DC has been applied to the working hydraulics of mobile machines, active vibration damping, and machine power management strategies. However, for the first time this technology is being investigated and applied to steering systems, which presents a unique opportunity to solve the pressing challenges and highlight the benefits of such systems. A DC steering system lends itself to high energy efficiency (lower fuel consumption/emissions), greater machine productivity and reduced operator fatigue, and active safety for counteracting instabilities. The paper presents the new concept; reviews the dynamic models of the hydraulics subsystem and the dynamics subsystem; summarizes the system synthesis with focus on stability; and finally describes the primary controller design based on modern control techniques via state space formulation and full state feedback methods. To allow for designing a controller at the system level, vehicle dynamics equations of motion and pressure-flow equations are merged together to form a single-input single-output (SISO) system with the desired input and output in mind. Simulation results are provided to validate the control algorithm relative to the specified performance requirements.
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.
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.
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.
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.
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.
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.
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

ABSTRACT

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.