bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconfigurable Pneumatic Clamping Device of Industry Manipulator Based on Toggle-Lever Force Amplifier in Series
Authors: Dou Yunxia , Wang Mingdi , Su Dongning , Zhong Kangmin
Published: July 2010

The clamping mechanism plays critical roles in industry manipulator. At present, the clamping mechanism of industry manipulator is most pneumatic drive, which action is rapid. However, for clamping the geometrically rough similar or similar, even complete same work piece, different designers tend to use different design schemes of pneumatic clamping device. Even the same designer may also frequent changing his clamping schemes, such as using different cylinder with different structure, different force amplifier, different clamping mechanism and clamping elements, and so on. The traditional design methods mentioned above are out-of-order and non instructive. The problem is especially critical for today’s manufacturing industry, which features short term, large quantity and individual demand design. This article describes a new innovation design idea of reconfigurable pneumatic clamping mechanism based on toggle-lever force amplifier in series and rod-less piston cylinder. Based on the idea, we designed a series of clamping devices featuring clear logic idea. The graphic example, corresponding formula of output force and mechanics characteristics curve are given which of important reference value and the guide meaning for engineering fields. The reconfigurable pneumatic clamping device of industry manipulator based on toggle-lever force amplifier in series and rod-less piston cylinder present in this paper has the following advantages: (1) Then using the same clamping device, we can realize the changing from external clamping to internal clamping expediently. What we should do is just changing the direction of compressed air in and out the rod-less piston cylinder utilizing its symmetry. (2) The elements of force amplifier and clamping device are all geometrically simple bars, but they have various functions. (3) The elements of force-transferring mechanism based on rolling higher pair and the elements for clamping the work piece both are geometrically simple rolling wheels or its deformation after cutting. They have resembled manufacturing technology but distinct functions. (4) Though the changes of shape, dimension or location of the basic components, the corresponding clamping device can be quickly designed to meet the needs of internal or external clamping to the work piece for different dimension, different shape and different clamping force. (5) Using the two-step or three-step force-amplifier, the device solved the shortcoming of lower press result in the smaller force of pneumatic drive system, and thus can be instead of the hydraulic clamping device in certain extent which easily leads to environmental pollution.
The Green, Digital Clamping Device Composed of Self-Locking Power Screw Driven by the Servo Motor
Authors: Liu Yang , Zhong Kangmin , Sheng Xiaoming , Wang Mingdi
Published: July 2010

Fluid transmission, such as hydraulic and pneumatic, is widely used in the fixtures in modern industry. But there are some disadvantages in these fixtures. First, too much loops and turns in the hydraulic or pneumatic systems have lead to lower energy utilization ratio and complicated structure. Second, oil emission in hydraulic system may cause environment pollution, and the noise in pneumatic system may cause pollution too. Third, fluid system always needs electro-hydraulic or electro-pneumatic transform elements for digital intelligent control, which will add the cost and the complexity of system. In order to overcome this disadvantage, a new kind of mechatronics clamping device is designed innovatively, which is driven by servo motor and translated along the self-locking power screw. So it was very simple with little transmission elements and has no high-speed mechanic components. By changing the geometry shape of basic link, different requirements for clamping forces and clamping situations can be satisfied. This new kind of clamping device has prominent advantages in green and digital aspects. Moreover, it can meet perfectly the requirements of short-cycle, high-volume production in modern manufacturing industry.
Adaptive Carbon Monoxide Kinetics for Exhaust Aftertreatment Modeling
Authors: Depcik Christopher , Loya Sudarshan , Srinivasan Anand
Published: July 2010

Future emission standards are driving the need for advanced control of both Spark (SI) and Compression Ignition (CI) engines. However, even with the implementation of cooled Exhaust Gas Recirculation and Low Temperature Combustion (LTC), it is unlikely that in-cylinder combustion strategies alone will reduce emissions to levels below the proposed standards. As a result, researchers are developing complex catalytic aftertreatment systems to meet these tailpipe regulations for both conventional and alternative combustion regimes. Simulating these exhaust systems requires fast and accurate models suitable for significant changes in inlet conditions. Most aftertreatment devices contain Platinum Group Metals because of their widely documented beneficial catalysis properties; examples include Diesel Oxidation Catalysts, Three-Way Catalysts and Lean NOx Traps. There are kinetic mechanisms available for each of these devices, but often they do not extrapolate well to other formulations. For example, Carbon Monoxide (CO) levels entering a catalyst are significantly different between an SI and CI engine. In addition, modifying engine control to utilize LTC operation can result in an increase in CO levels due to lower combustion efficiency. This adversely affects the conversion capabilities of a catalytic device through increased levels of CO inhibition. Finally, catalyst loading and metal dispersion differences between devices often prohibit a direct extension of kinetic constants. As a result, mechanisms often need recalibration for correct modeling capabilities. In order to begin creating a more predictive kinetic mechanism, this paper simulates CO oxidation as a function of different inlet concentration levels and metal loadings. While aftertreatment devices contain many reactions, modeling of one fundamental reaction is a first step to determine the feasibility of adaptive kinetics. In addition, research into the history of the CO oxidation mechanism over platinum illustrates a more accurate rate expression to utilize in deference to current modeling activities. The authors calibrate this expression to experimental data taking into account significant changes in inlet conditions, metal loading and dispersion values. Model fidelity is determined through the simulation of additional data not part of the initial calibration efforts. In addition, the paper discusses strengths and weaknesses of the model along with how other researchers can help foster adaptive kinetic development.
A New Off-Line Computer Model for Improving Width Reduction in Roughing Trains of Hot Strip Mills of Mobarakeh Steel Company
Authors: Eghtesad M. , Javid S. , Izadi J. , Rasouli M. , Bazargan-Lari Y. , Faghihi A.
Published: July 2010

Edging of slab is an important process to reduce and control width in the roughing area of hot strip mills. Width reduction amount that is required for edger in every pass is computed in the form of a very complicated on-line computer model. The model which previously was used for computation of width in roughing strip mill of Iran’s Foolad Mobarakeh Company did not have acceptable accuracy and caused many problems in final product width. Obviating these problems and adopting a reasonable and optimal way in allocating the width reduction amount of edger in every pass, the process of width reduction was put under close examination and an off-line computer model was written that precisely computes the width reduction. The performed computations by this model in roughing strip mill of this company were put to use; this was followed by very satisfactory results. Finally, according to the obtained results, the on-line model was corrected. Correction of the aforementioned model has had a significant effect in increase of quality and decrease of damages of hot strip mill products.
A Computational Study on Performance, Combustion and Emissions Characteristics of a Hydrogen-Fueled Internal Combustion Engine
Authors: Vudumu Shravan K. , Koylu Umit O.
Published: July 2010

Hydrogen is an alternative fuel that is considered to be one of the viable solutions to the increasing demands of clean and secure energy. Internal combustion engines fueled by hydrogen have the potential for higher power and efficiency with lower emissions when compared to gasoline. In the present study, advanced engine simulations were used to study the performance, combustion and emission characteristics of a hydrogen-fueled engine. Hydrogen fuel-specific combustion models were used to account for the distinctive characteristics of hydrogen combustion when compared to that of gasoline. The simulation results matched well with the already-published experimental data under similar engine operational conditions. NOx emissions were found to increase drastically after an equivalence ratio of 0.5 due to high combustion temperatures. EGR was found to be an effective way to reduce NOx emissions but compromised engine power and efficiency.
A Case Study of Drawbead Design of a Deep Drawn Rectangular Part Using FEM
Authors: Garci´a Zugasti Pedro de Jesu´s , Medelli´n Castillo Hugo Iva´n , de Lange Dirk Frederik
Published: July 2010

The deep drawing manufacturing process of sheet metal parts with complex shape has increased recently in applications such as in the automotive industry and the household appliances. The trial and error methods commonly used in defining the process parameters, cause high costs and large development times. The computer assisted analysis and simulations are being used more frequently to reduce the cost and development time of a product. The process parameters can be modified and evaluated using these computer simulations before the production is carried out. Therefore the defects of a part can be identified and eliminated, if possible, without the need of the traditional trial and error methods. This paper presents a case study of an industrial component that presented defects (wrinkles at the corners) in its deep drawing process. To eliminate these defects a drawbead was proposed and its optimal location was established using an optimization procedure based on finite element method (FEM). The FEM simulations were validated by measuring the thickness of the fabricated part. To evaluate the elimination of the wrinkle, the thickness of the sheet metal at the critical area was measured in the FEM simulation and compared with the thickness profile before and after the addition of the drawbeads. The results have shown that the design strategy based on FEM can be effectively used as a design tool to eliminate part defects in rectangular deep drawing process.
Measuring and Comparing Accuracy of Emissions Analyzers for Use With IC Engines
Authors: Cordon Dan , Beyerlein Steve , Steciak Judi , DenBraven Karen
Published: July 2010

Automotive emission analyzers vary in price from under $1000 to well over $100,000. Different analyzers use various technologies to detect exhaust concentrations, and differ in how they condition the sample — leading to a difference in price and performance. Manufacturer claims on accuracy from less expensive analyzers are often similar to much more expensive analyzers. With a variety of analyzers available in the Small Engine Research Facility (SmERF) at the University of Idaho, this often leads to confusion in reporting accuracy of exhaust gas measurements. This study benchmarks the performance of three different analyzers: A portable 5-gas analyzer using NDIR and electrochemical cells which costs ∼$5000, a portable 7-gas analyzer using separate sensors for each gas which costs ∼$10,000, and a FTIR spectrometer which costs ∼$100,000. High and low concentrations of single-species calibration gases (methane, carbon monoxide, carbon dioxide, nitrous oxide, hydrogen, and oxygen) were run through each machine. Initial findings showed that all species measured by the 5-gas analyzer were precise around the point of calibration, with CO and CO2 quite accurate across their whole range. The 7-gas analyzer was less accurate than the 5-gas when measuring CO, CO2, and O2, but was far more accurate for THC, NO, and NO2 measurements. The FTIR was very precise provided that water vapor was effectively removed and sample lines were adequately heated. Both of the less expensive analyzers showed reduced accuracy the further away from their calibration points. Because of high setup time, use of the FTIR should be limited to detailed emissions studies, and is not recommended for coarse tuning of an engine.
NOx Emissions Reduction Using Air Separation Membranes for Different Loads in Gas-Fired Engines
Authors: Biruduganti Munidhar , Gupta Sreenath , Bihari Bipin , Sekar Raj
Published: July 2010

Air Separation Membranes (ASM) could potentially replace Exhaust Gas Recirculation (EGR) technology in engines due to the proven benefits in NOx reduction but without the drawbacks of EGR. Previous investigations of Nitrogen Enriched Air (NEA) combustion using nitrogen bottles showed up to 70% NOx reduction with modest 2% nitrogen enrichment. The investigation in this paper was performed with an ASM capable of delivering at least 3.5% NEA to a single cylinder spark ignited natural gas engine. Low Temperature Combustion (LTC) is one of the pathways to meet the mandatory ultra low NOx emissions levels set by regulatory agencies. In this study, a comparative assessment is made between natural gas combustion in standard air and 2% NEA for different engine loads. Enrichment beyond this level degraded engine performance in terms of power density, Brake Thermal Efficiency (BTE), and unburned hydrocarbon (UHC) emissions for a given equivalence ratio. The ignition timing was optimized to yield maximum brake torque for standard air and NEA. The parasitic loss associated with the usage of ASM technology is presented. It was observed that with 2% NEA, for a similar fuel quantity, the equivalence ratio (Ψ) increases by 0.1 relative to standard air conditions. Analysis showed that lean burn operation along with NEA could pave the pathway for realizing lower NOx emissions with a slight penalty in BTE.
Simulation of Turbulent Combustion in Inert Porous Media Using a Thermal Non-Equilibrium Model
Authors: de Lemos Marcelo J. S.
Published: July 2010

The objective of this paper is to show numerical simulations of combustion of an air/methane mixture in porous materials. Here, a model that considers the intrapore levels of turbulent kinetic energy is used. Transport equations are written in their time-and-volume-averaged form and a volume-based statistical turbulence model is applied to simulate turbulence generation due to the porous matrix. Different thermo-mechanical models are compared, namely Laminar, Laminar with Radiation Transport, Turbulent, Turbulent with Radiation Transport. Combustion is modeled via a unique simple closure. Results indicate that a substantially different temperature distribution is obtained depending on the model used. In addition, for high excess air, peak gas temperatures are reduced.
An Assessment of the Importance of Secondary Spray on a Water Sprinkler Scenario
Authors: Brown Alexander L. , Yoon Sam S.
Published: July 2010

Recent development efforts have resulted in new models that are capable of predicting water spray interactions with solid surfaces for a wide range of drop sizes and velocities. These models provide a reasonable approximation to single drop impact events, and significantly improve the expected accuracy of the splash. The models are implemented in the Vulcan software, a CFD code for fire modeling. We wanted to understand how important the splash is to a suppression scenario and the implications of common simplifying assumptions. A scenario with several rectangular objects located beneath a water suppression system is examined. This scenario was designed to be representative of an industrial fire and suppression situation. We compare the deposition masses on the surfaces for three cases, one with the recently developed model, another assuming no splash, and another assuming all splashing drops eject an excessive fraction of their mass. The results of the higher fidelity predictions compared with the more commonly employed and simpler assumptions suggest the importance of splashing to the outcome of an industrial water sprinkler fire suppression event.
Reconfigurable Green Hydraulic-Mechanical Compound Transmission Systems Based on Rod-Less Hydraulic Cylinder and Two-Steps Force Amplifier With Self-Locking Function
Authors: Si Guangju , Zhong Kangmin
Published: July 2010

Four kinds of reconfigurable green hydraulic-mechanical compound force-amplifying systems with self-locking function are introduced in this paper. The systems are both formed by a rod-less hydraulic cylinder and a two-steps force-amplifying mechanism in which the first step force-amplifying mechanism is a toggle mechanism working in the position of over dead-center, a toggle or lever mechanism is adopted as the second step force-amplifying mechanism. The working principles and mechanical calculating formulas of the systems are given as well. The distinct advantage of these devices is that with the functions of force-amplifying and self-locking provided by the first-step over dead-center toggle, the size of the piston in rod-less hydraulic cylinder can be reduced obviously, at the same time a continuous force can be obtained through the force output component without hydraulic cylinder in working and any energy consuming, thus these systems have obvious advantages of saving-energy. In addition the results show that all these hydraulic-mechanical compound drive systems can be quickly reconfigured only by changing the second step force-amplifying mechanism, while the basic structure of cylinder assembly, piston assembly and the first step force-amplifying mechanism does not need to be changed. By this means the systems will get advantages such as low cost, high capability and flexibility, short empoldering period and man-hour in practice.
Design for Multi-Position Pneumatic-Mechanical Press Based on Two-Step Orthogonal Toggle Force Amplifier and Floating Rolling Higher Pair
Authors: Wang Chuanyang , Qian Qiubo , Zhong Kangmin , Dou Yunxia
Published: July 2010

Presses are manufacturing tools capable of exerting tensile and/or compressive stresses on the workpiece to accomplish mechanical fabricating operations. Using green machinery design principle, novel multi-position presses, composed of a two-step orthogonal toggle force-amplifying mechanisms and rod-less pneumatic cylinders with floating rolling higher pair, are proposed. The working principle of the multi-position press is investigated. Equations of mechanical advantage and output force of multi-position press are developed. Example is given to show the efficiency of the two-step toggle actuator. Advantages of the multi-position press include environmental friendliness, overall structure simplicity and ability of imposing equal output force on workpieces simultaneously.
Reduction of Nitric Oxide Emission From a SI Engine by Water Injection at the Intake Runner
Authors: Wang Jun-Kai , Li Jing-Lun , Wu Ming-Hsun , Chen Rong-Horng
Published: July 2010

The effects of pulsed water injection at the intake port of a modern port fuel injection gasoline engine were investigated. A port water injection system was developed and the water injector was installed on the intake runner of the single cylinder motorcycle engine at a location upstream of the fuel injector. The results show that with a water-gasoline injection ratio of 1, more than 80% of NOx emission can be removed. The trade-off was a 25% reduction in torque output at 4000 rpm and 20% throttle opening; however, the decrease on torque can be controlled to be within 5% by reducing water-gasoline mass ratios to less than 0.6. We also performed NOx emission modeling using one-dimensional gas dynamics code with extended Zeldovich mechanism, and consistent results were found between numerical prediction and experimental measurements. The port water injection approach appears to be an effective means for reducing NOx emission from a gasoline engine at low speed and high load conditions without largely sacrificing the performances on torque output and unburned hydrocarbon emissions.
Combustion of Cattle Biomass as a Supplementary Fuel in a Small Scale Boiler Burner Facility for NOx and Mercury Reductions
Authors: Oh Hyukjin , Annamalai Kalyan , Sweeten John M. , Rynio Christopher , Arnold Witold
Published: July 2010

Combustion of cattle biomass (CB) as a supplementary fuel has been proposed for reducing emissions of NOx, Hg, SO2, and nonrenewable CO2 in large coal-fired power plants. It has benefits to power industries for lowering coal consumption and fuel costs and to animal industries for disposing burdensome agricultural wastes from large animal feeding operations. In order to develop environmentally friendly thermo-chemical energy conversion technologies that can utilize CB for NOx and Hg reductions in existing coal-fired power plants, co-firing and reburning experiments involving CB and coal were performed in a small-scale 30 kWt (100,000 Btu/h) downward fired boiler burner facility. The co-firing results are mainly presented and discussed. Preliminary reburn results are also reported. The results show that the pulverized CB can serve as a supplementary fuel for the coal-fired boilers, and combustion of the CB with coals shows reductions in NOx and Hg emissions. It is believed that 1) most of the fuel-nitrogen in the CB existed in forms of NH3 or urea which led the high NOx reductions and 2) burning the CB containing high chlorine (Cl) produced large amounts of Cl species (mainly HCl) which oxidized the elemental Hg in the flue gas, hence the Hg emissions were reduced. The equivalence ratio (φ), an inverse value of the stoichiometric ratio, was considered as a key parameter to achieve high NOx reductions. Higher NOx and Hg reductions were measured under fuel-rich conditions (φ > 1.0). It appeared that the effect of the unburned carbon (UBC) was much stronger on the Hg reductions than that of Cl.
FireExplorer: A Graphical User Interface for Fire Modeling
Authors: Swensen D. , Borodai S. , Eddings E. , McDonald M. , Swede D. , Halligan M. , DesJardin P. , Bockelie M.
Published: July 2010

Fire modeling is used by Fire Protection Engineers and fire researchers to evaluate fire spread and damage for a wide variety of applications, including evaluating building fire protection systems, developing fire safety equipment and assisting in legal proceedings by assessing the source of a fire. Historically, empirical and zonal models that contained limited physics and accuracy were used for these analyses. Today, there is a greater emphasis on using Computational Fluid Dynamic (CFD) based models because these models can capture localized conditions (e.g., local temperatures, heat fluxes, gas composition, smoke travel) required to perform a proper analysis of a fire situation which can be crucial when evaluating product designs, safety procedures, fire re-enactments and smoke transport. Although several fire modeling software packages are available, the Fire Dynamics Simulator (FDS) package available from NIST is commonly used due to the fire modeling community having confidence in this tool because it has been validated. In this paper is described a new software package, FireExplorer®, which can be used to simplify the time-consuming and complex tasks required to create the inputs for the NIST FDS model, execute and monitor the simulation and view the results.. The tool employs an easy to use graphical user interface designed for use by the non-modeling expert. The tool contains all the capabilities required to set-up, execute, analyze and visualize a fire simulation in an environment that is robust, flexible and extensible.
Optimization of Force and Moment Balance of a Four-Bar Linkage Using Multi-Objective Genetic Algorithm
Authors: Farmani Mohammad Reza , Jaamiolahmadi A.
Published: July 2010

In this study, force and moment balance of a four-bar linkage is implemented by using a Multi-Objective Genetic Algorithm (MOGA). During the time that an unbalanced linkage moves, it transmits shaking forces and moments to its surroundings. These transmitted forces and moments may cause some serious and undesirable problems such as vibration, noise, wear, and fatigue. In the current problem, the concepts of inertia counterweights and physical pendulum are utilized to complete balance of all mass effects (both linear and rotary, but excluding external loads), independent of input angular velocity. In this paper, Non-Dominated Genetic Algorithm (NSGA-II) is applied to minimize two objective functions subject to some different design constraints. The applied algorithm produced a set of feasible solutions called Pareto optimal solutions for the design problem. Finally, a fuzzy decision maker is applied to select the best solution among the obtained Pareto solutions based on design criteria. The results show that obtained solutions minimize the weights of applied counterweights and eliminate both shaking forces and moments transmitted to the ground, simultaneously.
Simulation of Combustion and Thermal-Flow Inside a Pyroscrubber
Authors: Zhao Lei , Wang Ting
Published: July 2010

A pyroscrubber is the device used in petroleum coke Calcining industry to oxidize the carbonaceous contents, including hydrocarbon volatiles of the exhaust gas from the calcination kiln, so as to recover energy to produce electricity and leave no more than small traces of unburned volatiles, solid carbon, ashes, or emissions (e.g. CO, NOx and SOx) in the flue gas finally discharged. Motivated by the need to maximize the energy recovery and reduce pollutant emission from the pyroscrubber, a 3-D computational model is developed to simulate the combustion and thermal-flow phenomena inside the pyroscrubber to help seek means to reduce emissions and increase energy density for downstream power generation. CFD model validation is achieved by comparing baseline case results with the plant measurement data of temperature and NOx emission. The simulation results show that the specially designed high-bay wall structure generates a strong mixing zone forcing combustion to happen at an earlier stage and helps to efficiently utilize the main chamber space. A well balanced amount of excess air is favorable in generating more energy output and lowering NOx emission. Incomplete combustion with sub-stoichiometric air cuts NOx emission, but leads to less total energy output, lowers gas temperature and increased CO emission. A multistage burning strategy is introduced and studied and results show it successfully cuts emission without compromising energy (electricity power) output.
Warranty Cost Prediction Using the Mahalanobis-Taguchi System
Authors: Kestle Rodney , Cudney Elizabeth
Published: July 2010

In any competitive market, businesses need to differentiate their offerings. Many industries use a warranty as an offering that not only differentiates the product or service, but also extends the customer’s expected durability of the product or service. By offering to share the risk of a customer’s purchase in the form of a warranty, a business assumes the cost of poor quality and therefore should have a vested interest to reduce this cost thus maximizing its profits. Warranty cost prediction methods are used by many leading companies, but these methods typically only focus on failure reduction as cost avoidance. Additional dimensions should be considered when predicting warranty cost. This paper presents the application of the Mahalanobis-Taguchi System to forecast warranty cost based on multivariate data. Using Mahalanobis-Taguchi System, a product or service’s warranty cost can be predicted using multiple characteristics thus providing a more complete estimate. The Mahalanobis-Taguchi System also enables businesses to estimate their warranty cost as early as conceptual design, due to the method’s ability to forecast based on small, correlated data sets. A case study utilizing warranty data is also provided to illustrate the technique.
Further Studies of Alternative Jet Fuels
Authors: Mordaunt Christopher J. , Lee Seong-Young , Kalaskar Vickey B. , Mensch Amy , Santoro Robert J. , Schobert Harold H.
Published: July 2010

Future gas turbine technology may require that liquid fuels play an additional role as a coolant over a wide range of combustion-chamber operating conditions. Additionally, in order to satisfy greater efficiency and performance goals, gas turbine operating temperatures and pressures are steadily increasing. Given the desire to reduce dependence on foreign fuels and that current hydrocarbon fuels, such as JP-8, are prone to thermal or catalytic decomposition at such elevated conditions, there is great interest in utilizing alternatively-derived liquid fuels. The successful development of a versatile, multiple-use fuel must achieve the desired operational characteristics of high combustion efficiency, excellent combustion stability, acceptable pollutant emission levels, and compatibility with current engine seals. Combustion instability represents a critical area of concern for future gas turbine engines that may burn alternative fuels. Combustion instability is characterized by large, unsteady combustion-chamber pressure oscillations which occur at the characteristic frequencies associated with the acoustic modes of the combustor. The occurrence of combustion-driven instabilities is closely tied to the details of the injection and fuel-air mixing processes, the heat release characteristics, and the degree to which heat release rate couples with the acoustics of the combustor. Additionally, the efficiency and emissions characteristics are also largely determined by the fuel injection, atomization, and mixing processes associated with combustion. As fuel properties and composition vary, effects on combustion efficiency and emissions, especially the formation of nitrogen oxides (NOx) and soot, can be expected. Therefore, changes in these processes attributed to differing fuel properties can have a dramatic affect on the combustion characteristics and require careful consideration through a well-coordinated combustion research program. The current study investigates whether a coal-based aviation fuel, JP-900, which has the required thermal stability attributes, also satisfies the engine combustion requirements. Additionally, a Fischer-Tropsch fuel and a volumetric 50/50 blend of JP-8 and the Fischer-Tropsch fuel are studied. Previous studies of coal-based fuels have shown that soot production can be a significant problem due to the higher aromatic content than found in conventional fuels. However, improvements in the fuel refinement processes have helped reduce this problem. Experiments included in this current research effort involve studying the combustion instability patterns, the pollutant emission levels, and sooting propensity of coal-based and Fischer-Tropsch fuels as compared to JP-8. The experimental setup consists of an optically-accessible model gas turbine dump combustor, with provisions for laser extinction measurements, which utilizes a Delavan hollow-cone pressure atomizer for fuel injection.
CFD Simulation of Entrained Flow Gasification With Improved Devolatilization and Char Consumption Submodels
Authors: Kumar Mayank , Zhang Cheng , Monaghan Rory F. D. , Singer Simcha L. , Ghoniem Ahmed F.
Published: July 2010

In this work, we use a CFD package to model the operation of a coal gasifier with the objective of assessing the impact of devolatilization and char consumption models on the accuracy of the results. Devolatilization is modeled using the Chemical Percolation Devolitilization (CPD) model. The traditional CPD models predict the rate and the amount of volatiles released but not their species composition. We show that the knowledge of devolatilization rates is not sufficient for the accurate prediction of char consumption and a quantitative description of the devolatilization products, including the chemical composition of the tar, is needed. We incorporate experimental data on devolatilization products combined with modeling of the tar composition and reactions to improve the prediction of syngas compositions and carbon conversion. We also apply the shrinking core model and the random pore model to describe char consumption in the CFD simulations. Analysis of the results indicates distinct regimes of kinetic and diffusion control depending on the particle radius and injection conditions for both char oxidation and gasification reactions. The random pore model with Langmuir-Hinshelwood reaction kinetics are found to be better at predicting carbon conversion and exit syngas composition than the shrinking core model with Arrhenius kinetics. In addition, we gain qualitative and quantitative insights into the impact of the ash layer surrounding the char particle on the reaction rate.
Mathematical Modeling of Biomass Pyrolysis
Authors: Rahbari A. , Bidabadi M. , Azimi M.
Published: July 2010

In this research, the structure of laminar, one-dimensional and steady flame propagation in uniformly premixed particle-wood is analyzed. The structure of the flame is composed of three zones: a preheat zone, a narrow reaction zone and a post flame zone. In the preheat zone, the rate of reaction between fuel and oxidizer is assumed to be small and also it is presumed that the fuel particles vaporize to yield a gaseous fuel of known chemical structure when enter the reaction zone. Then in the reaction zone, composed of gas, tar and char combustion, the convective terms and vaporization terms in the conservation equations are presumed to be small and in the post flame zone, the diffusive terms in the conservation equations are assumed to be small in comparison with other parameters. The governing equations in each zone, considering these assumptions, are solved using the required boundary and matching conditions. Consequently, the variation of burning velocity and flame temperature as a function of equivalence ratio are presented as the outcome of this research.
Effects of the Injection Parameters on the Emissions of a Heavy Duty Diesel Engine
Authors: Yılmaz M. , Gul M. Zafer , Yukselenturk Y. , Akay B. , Koten H.
Published: July 2010

It is estimated by the experts in the automotive industry that diesel engines on the transport market should increase within the years to come due to their high thermal efficiency coupled with low carbon dioxide (CO2) emissions, provided their nitrogen oxides (NOx) and particulate emissions are reduced. At present, adequate after-treatments, NOx and particulates matter (PM) traps are developed and industrialized with still concerns about fuel economy, robustness, sensitivity to fuel sulfur and cost because of their complex and sophisticated control strategy. New combustion processes focused on clean diesel combustion are investigated for their potential to achieve near zero particulate and NOx emissions. Their main drawbacks are increased level of unburned hydrocarbons (HC) and carbon monoxide (CO) emissions, combustion control at high load and limited operating range and power output. In this work, cold flow simulations for a single cylinder of a nine-liter (6 cylinder × 1.5 lt.) diesel engine have been performed to find out flow development and turbulence generation in the piston-cylinder assembly. In this study, the goal is to understand the flow field and the combustion process in order to be able to suggest some improvements on the in-cylinder design of an engine. Therefore combustion simulations of the engine have been performed to find out flow development and emission generation in the cylinder. Moreover, the interaction of air motion with high-pressure fuel spray injected directly into the cylinder has also been carried out. A Lagrangian multiphase model has been applied to the in-cylinder spray-air motion interaction in a heavy-duty CI engine under direct injection conditions. A comprehensive model for atomization of liquid sprays under high injection pressures has been employed. The combustion is modeled via a new combustion model ECFM-3Z (Extended Coherent Flame Model) developed at IFP. Finally, a calculation on an engine configuration with compression, spray injection and combustion in a direct injection Diesel engine is presented. Further investigation has also been performed in-cylinder design parameters in a DI diesel engine that result in low emissions by effect of high turbulence level. The results are widely in agreement qualitatively with the previous experimental and computational studies in the literature.
Simulation of Combustion and Thermal-Flow Inside a Petroleum Coke Rotary Calcining Kiln: Part 2—Analysis of Effects of Tertiary Airflow and Rotation
Authors: Zhang Zexuan , Wang Ting
Published: July 2010

A computational model is established to simulate the combustion and thermal-flow behavior inside a petcoke rotary calcining kiln. The results show that peak temperature is located at the tertiary air zone and a cold region that exists between the natural gas combustion zone and the tertiary air zone causes the coke bed to lose heat to the gas stream. The cold tertiary air injections reduce the gas temperature inside the kiln, so preheating the tertiary air using extracted gas or other waste energy is essential to saving energy. The devolatilization rate and location have a pronounced effect on the simulated temperature distribution. As the calcining kiln rotates, the tertiary air injection nozzles will move relative to the coke bed and exert cyclic air-bed interactions. At zero angular position, the air injection nozzles are diametrically located away from the bed, so the interactions between the tertiary air jets and coke bed are minimal. As the kiln rotates to a 180-degree position, the stem of the air injection nozzles are actually buried inside the coke bed with the nozzles protruding outward from the bed. At this position, the tertiary air jets will provide a fresh layer of air just above the coke bed, and the interaction between the air flow and coke bed becomes strong. The 45° rotational angle case shows a better calcination with a 100 K higher bed surface temperature at the discharge end compared to the rest of rotational angles. Without including the coke fines combustion and the coke bed, the lumped gas temperature for the rotational cases shows a peak temperature of 1,400 K at Z/D = 2, which is due to natural gas combustion; the lowest temperature is around 1,075 K at two locations, Z/D = 4 and 8, respectively. The exhaust gas temperature is approximately 1,100K.
Static Tensile Strength and Process Optimization of Gas Metal Arc Welding (GMAW) for 1.5 mm Electro-Galvanized Transformation Induced Plasticity 780 (TRIP780) Steel Joint for Automotive Body Structural Applications
Authors: Koganti Ramakrishna , Jiang Cindy , Karas Chris
Published: July 2010

With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to Heat affected Zones (HAZ) at the weld joint. In this study Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 1.5 mm Electro Galvanized (EG) Transformation Induced Plasticity 780 (TRIP780) to itself was investigated. The objective of the study was to understand the wire feed rate and torch speed influence on lap joint strength. Design of Experiments (DOE) was conducted to understand the wire feed and torch speed influence on tensile strength. Based on the statistical analysis, wire feed rate and torch speed were significant factors on static tensile strength. Two way interaction effect between wire feed and torch speed was significant. Metallurgical properties of the lap joints were evaluated using optical microscopy. No significant drop in hardness at HAZ, however, significant hardening was observed at the base metal and weld fillet interface.
Investigation of Residual Stress Development During Swage Autofrettage, Using Finite Element Analysis
Authors: Gibson Michael C. , Hameed Amer , Hetherington John G.
Published: July 2010

Swaging is one method of autofrettage, a means of pre-stressing high-pressure vessels to increase their fatigue lives and load bearing capacity. Swaging achieves the required deformation through physical interference between an oversized mandrel and the bore diameter of the tube, as it is pushed through the tube. A Finite Element model of the swaging process was developed, in ANSYS, and systematically refined, to investigate the mechanism of deformation and subsequent development of residual stresses. A parametric study was undertaken, of various properties such as mandrel slope angle, parallel section length and friction coefficient. It is observed that the axial stress plays a crucial role in the determination of the residual hoop stress and reverse yielding. The model, and results obtained from it, provides a means of understanding the swaging process and how it responds to different parameters. This understanding, coupled with future improvements to the model, potentially allows the swaging process to be refined, in terms of residual stresses development and mandrel driving force.
Influence of Lubricants on Advanced High Strength Steel Tubes in Bending Process
Authors: Koganti Ramakrishna , Angotti Sergio , van Riemsdijk Isadora , Nelson Robert C. , Smith Jill
Published: July 2010

To reach safety, emissions, and cost objectives, manufacturers of automotive body structural components shape thin gauge, high strength steel tube using a series of manufacturing steps that often include bending, preforming and hydroforming. Challenging grades and bend severity require a sensitive optimization of the tubular bending process. Lubricants play a significant role in establishing a successful bending process. In this study, the performance of two lubricants, Hydrodraw 551 and HFO 20, were investigated for bending Dual Phase 780 (DP780) and High Strength Low Alloy 350 (HSLA350) thin-walled steel tubes. Formability success was evaluated in terms of wrinkling, thinning strain and final geometry. Lubricant performance was found to be sensitive to grade and application site. HFO 20 was found to be a poor choice for bending DP780 tube.
An Experimental Study Investigating the Corrosion Behavior of Cu-Ni Alloys in Waters Treated and Untreated With Anti-Corrosives
Authors: LaCoursiere Marissa , Aidun Daryush K. , Marzocca Pier , Lee Howard
Published: July 2010

This paper discusses an experimental study on how water quality affects the corrosion rate of Cu-Ni Alloys, such as those used within a heat exchanger system. Various types of water suitable for the heat exchanger operation have been tested to predict the duration during which corrosion would become a risk. Since corrosion is governed by electrochemistry, an electrochemical experimental setup was designed, consisting of a three-electrode electrochemical cell designed to simulate the on-site state and conditions of a 90–10 Cu-Ni tube bundle inside the heat exchanger. The working electrode in use is a 90-10 Cu-Ni Rotating Cylinder Electrode (RCE). The electrolyte solution was varied with different pH values, temperature and compositions. The corrosion rate was measured by use of the Tafel method. Experiments were performed with two solutions; De-Ionized water and Tap water. Further experimentation with anti-corrosives was also performed. All measurements were produced using a G300 Gamry® Potentiostat (computer controlled) conjugated with two general purpose electrochemical softwares: Gamry Framework® and Gamry Echem Analyst®. Trends of the corrosion rate as a function of pH and temperature were analyzed. Field Emission Scanning Electron Microscope (FE-SEM) tests have also been performed to determine the products, methods and elemental effects of the corrosion. Results and discussions are provided with pertinent conclusions.
Dual exposure, two-photon, conformal phase mask lithography for three dimensional silicon inverse woodpile photonic crystals
Authors: Shir Daniel J. , Nelson Erik C. , Chanda Debashis , Brzezinski Andrew , Braun Paul V. , Rogers John A. , Wiltzius Pierre
Published: July 2010

The authors describe the fabrication and characterization of three dimensional silicon inverse woodpile photonic crystals. A dual exposure, two-photon, conformal phasemask technique is used to create high quality polymer woodpile structures over large areas with geometries that quantitatively match expectations based on optical simulations. Depositing silicon into these templates followed by the removal of the polymer results in silicon inverse woodpile photonic crystals for which calculations indicate a wide, complete photonic bandgap over a range of structural fill fractions. Spectroscopic measurements of normal incidence reflection from both the polymer and silicon photonic crystals reveal good optical properties.
A Generalized Linear-Quadratic Model for Radiosurgery, Stereotactic Body Radiation Therapy, and High–Dose Rate Brachytherapy
Authors: Wang Jian Z. , Huang Zhibin , Lo Simon S. , Yuh William T. C. , Mayr Nina A.
Published: July 2010

A generalized mathematical model for the relation between radiation dose and tumor cell death enables better treatment planning and dose schedule designs for current targeted high-dose radiation therapies in cancer.
Your Inner Clock Is on Steroids
Authors: Buettner Christoph
Published: July 2010

The adrenal gland—and the glucocorticoids it secretes—help stabilize and reset our bodies' inner clocks.
Divide and Conquer
Authors: Morozov Alexei
Published: July 2010

Expression of genes involved in chromosomal stability may be a better marker of tumor aggressiveness than tumor grade.
Differential Selection of Single-Step AmpC or Efflux Mutants of
Pseudomonas aeruginosa
by Using Cefepime, Ceftazidime, or Ceftobiprole
Authors: Queenan Anne Marie , Shang Wenchi , Bush Karen , Flamm Robert K.
Published: July 2010

Single-step
Pseudomonas aeruginosa
mutants, selected with ceftobiprole, ceftazidime, or cefepime, were generated at frequencies of 10
−6
to <10
−9
at two and four times the MIC. The chromosomal AmpC β-lactamase activity was increased in all ceftazidime-selected mutants. Mutants selected with cefepime either increased AmpC activity or upregulated expression of the
mexXY
efflux genes. Mutants selected with ceftobiprole did not overexpress AmpC; 90% of these produced elevated levels of
mexXY
RNA, indicating that increased efflux, not AmpC derepression, is the predominant response to ceftobiprole during first-step mutations in
P. aeruginosa
.