bluuebunny/crossref_metadata_2025 huggingface dataset:
Challenges in Globally Distributed Design Teams: A Case Study
Authors: Hayes C. C.
Published: May 2009

This paper describes barriers to effective collaboration between geographically distributed experts jointly participating in design of medical products. The barriers were observed during a study conducted at a company which produces implantable medical devices such as pacemakers and defibulators, but the issues are typical of most international product producing companies. The company commissioned the study because they experienced serious manufacturing difficulties after moving their manufacturing facility to a new location where labor was less expensive, several thousand miles distant from design facility. The company suspected that the difficulties stemmed from insufficient communication and collaboration between the now distant design engineers and manufacturing engineers, but they lacked a sufficiently detailed understanding of the causes to formulate effective solutions. Electronic tools had not resolved the problems. The study found that the added distance greatly exacerbated many existing design/manufacturing collaboration challenges that occur in most organizations even when the two are located at the same site. Additionally, distance resulted in a decay of familiarity between sites with the people, processes and expertise at the other site. More explicit structure and incentives were needed to help distant team members overcome the added collaboration difficulties created by distance. The study concluded that one while one needs appropriate electronic tools to make it possible for distant design team members to communicate easily, additionally, an organization must provide appropriate processes, incentives and resources to motivate people to collaborate over distance.
In-Plane Free Vibration of Curved Beams Using Finite Element Method
Authors: Yang F. , Sedaghati R. , Esmailzadeh E.
Published: May 2009

Curved beam-type structures have many applications in engineering area. Due to the initial curvature of the central line, it is complicated to develop and solve the equations of motion by taking into account the extensibility of the curve axis and the influences of the shear deformation and the rotary inertia. In this study the finite element method is utilized to study the curved beam with arbitrary geometry. The curved beam is modeled using the Timoshenko beam theory and the circular ring model. The governing equation of motion is derived using the Extended-Hamilton principle and numerically solved by the finite element method. A parametric sensitive study for the natural frequencies has been performed and compared with those reported in the literature in order to demonstrate the accuracy of the analysis.
Making Design Reviews Count
Authors: Beiter Kurt , Ishii Kosuke , Karandikar Harshavardhan
Published: May 2009

Design reviews are one of the most established product-development project management techniques to identify and eliminate errors in product design before they physically manifest themselves either in a prototype or in the final product. Design reviews are typically embedded within an overall product-development project management process consisting of multiple stages separated by decision gates. The specific goal, structure and content of a design review depend upon the stage and time at which it is performed. In the process of working with a number of large companies on their technology and product development processes we observed that the actual practice of design reviews often falls well short of the companies’ own stated objectives. We examine the reasons for this in our paper, the chief among them being the often misleading application and lack of clarity and brevity in the review process. These problems can be clearly highlighted and rectified by the application of the CVCA and FMEA tools to the design review process itself. Thus, design reviews can be made more efficient and effective and made to count!
Dynamic Analysis of an Amphibious Single Wheel Robot, Part 1: Moving in Straight Path
Authors: Marzban Mostapha , Alasty Aria
Published: May 2009

A single wheel, gyroscopically stabilized robot is a sharp-edged wheel actuated by a spinning flywheel for steering and a drive motor for propulsion. The spinning flywheel acts as a gyroscope to stabilize the robot and it can be tilted to achieve steering. In this paper first the kinematics of a single wheel robot, like Gyrover, in water is considered and then a simple mechanism for its movement in water is proposed. After hydrodynamic analysis of the robot a complete dynamics model is designed with Lagrange energy method. The only simplification used here is neglecting the added mass effect in hydrodynamic analysis. This complete model can be used for examining the behavior of the robot in designing a controller. This work is a significant step towards a fully automatic control of such a dynamically stable but statically unstable robots.
Integrating Technology Obsolescence Considerations Into Product Design Planning
Authors: Feldman Kiri , Sandborn Peter
Published: May 2009

Technology life cycles affect a product manager’s ability to sustain systems through their manufacturing and field lives. The lack of availability of critical parts and technologies poses a challenge not only to the acquisition community, but to customers of products that must be maintained for long periods of time. Technology obsolescence has an especially serious impact on systems that have significant electronics content because electronic parts are quickly obsoleted in favor of newer, higher performance components. In this study, market availability data was analyzed for operational amplifiers, a technology integral to most electronic products, and for flash memory devices. Procurement lifetimes are shown to have shrunk since operational amplifiers emerged on the market. Algorithms for forecasting electronic part obsolescence are proposed and the ramifications of electronic part obsolescence on product design planning are discussed.
A Novel Approach to Quantifying Designer’s Mental Stress in the Conceptual Design Process
Authors: Zhu Shan , Yao Shengji , Zeng Yong
Published: May 2009

The objective of this paper is to quantify designer’s mental stress during the conceptual design process. Quantifying the designer’s mental stress would assist the effort of understanding the designer’s creative and innovative process. In this paper, Recursive Object Modelling (ROM) is used as a formal tool to represent the designer’s mental state in each step of the conceptual design process. During the conceptual design process, designers usually describe the design states using natural language, combined with sketches. The description based on natural language will be transformed into ROM diagram through the lexical, syntactic, and structure analysis. A cognitive experiment, which is to design a new litter-disposal system in a passenger compartment located in the trains of NS (Dutch Railways), is built to study designer’s thinking process. ROM is used to analyze and quantify the designer’s mental stress based on the protocol data collected in the experiment. The validation through the cognitive experiment shows that ROM is an efficient design evaluation methodology, which reflects the nature and the characteristics of the design process. The designer’s mental stress presents dynamic, nonlinear, and spiral trend.
Plain and Full Floating Bearing Simulations With Rigid Shaft Dynamics
Authors: McLuckie Ian , Barrett Scott
Published: May 2009

This paper shows a promising predictive bearing model that can be used to reduce turbocharger bearing system development times. Turbocharger development is normally done by varying design parameters such as bearing geometry in a very time consuming experimentation process. Full Floating Bearings (FFB) are used in most automotive turbochargers and, due to emissions regulations, there has been a push towards downsizing engines and applying turbo charging to generate optimized engine solutions for both gasoline and diesel applications. In this paper the turbocharger rotor is regarded as being rigid, and the equations of motion are solved using the Bulirsch Stoer time integration scheme. These equations are solved simultaneously with the bearing model which is used also to determine nonlinear stiffness and damping coefficients. The bearings are solved using a Rigid Hydro Dynamic (RHD) Finite Difference Successive Over Relaxation (SOR) scheme of Reynolds equation that includes both rotational and squeeze velocity terms. However the solver can also consider bearing and rotor elasticity in a Multi-Body Dynamic (MBD) and Elasto-Hydro Dynamic (EHD) combined solution. Two bearing types have been studied, a plain grooved (PGB) and a full floating bearing (FFB) for comparative purposes. The mathematical models used are generic and suitable for whole engine bearing studies. The results in this paper show they are suitable for determining the onset of turbocharger bearing instability, and also the means by which bearing instability may be suppressed. The current study has investigated forced response with the combined effects of gravity and unbalance. It is worth noting that the effects of both housing excitation and aerodynamic excitation from the compressor and turbine can be easily accommodated, and will be the subject of a future paper. Other topics introduced here that will be explored further in the future include the effect of bearing and rotor flexibility in the MBD and EHD solution and the use of automatically generated stiffness and damping coefficients for any bearing geometry.
Nonlinear Formulation for Flexible Multibody System Applied With Thermal Load
Authors: Liu Jinyang , Lu Hao
Published: May 2009

In this paper, temperature variation and dynamic performance of flexible multibody system applied with thermal load are investigated. Considering thermal strain and geometric nonlinear terms, heat conduction equations and dynamic equations for a flexible beam are derived, and then the system heat conduction equations and dynamic equations of flexible multibody system are assembled, and temperature, kinematic and driving constraint equations are used to obtain Lagrange’s equations of the first kind with Lagrange multipliers. Simulation of a rotating hub-beam system with simply-supported boundary condition is carried out to show the softening effect of the beam with temperature increase. Finally, thermal bending of flexible beam system applied with heat flux at upper surface is investigated. Coupling between rotational motion and transverse deformation as well as sudden change of constraint forces and axial stresses are shown to reveal the characteristics of thermal shock.
Dynamics of Large Membrane for Solar Sail-Craft
Authors: Nakaya Koji , Nishimaki Shuhei , Mori Osamu , Kawaguchi Jun’Ichiro
Published: May 2009

This paper discusses dynamics of large membrane for achieving spinning solar sail-craft proposed by the Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA). For comprehending the dynamics, firstly, two types of grand-scale experiments were conducted. One was an ice rink experiment. The other was a balloon experiment. In the both experiments, we succeeded in deploying 10m and 20m diameter membrane and observing the motion. Secondly, we constructed a numerical model using a multi-particle method, and numerical simulations were conducted. We drew a comparison between results of experiments and numerical simulations. The effectively of the multi-particle model was then indicated in this paper.
Fractional Optimal Control of a Distributed System Using Eigenfunctions
Authors: Agrawal Om P.
Published: May 2009

This paper presents a formulation and a numerical scheme for Fractional Optimal Control (FOC) for a class of distributed systems. The fractional derivative is defined in the Caputo sense. The performance index of a FOCP is considered as a function of both the state and the control variables, and the dynamic constraints are expressed by a Partial Fractional Differential Equations (PFDEs). Eigenfunctions are used to eliminate the space parameter, and to define the problem in terms of a set of state and control variables. This leads to a multi FOCP in which each FOCP could be solved independently. Several other strategies are pointed out to reduce the problem to a finite dimensional space, some of which may not provide a decoupled set of equations. The Calculus of Variations, the Lagrange multiplier, and the formula for fractional integration by parts are used to obtain Euler-Lagrange equations for the problem. The numerical technique presented in [1] is used to obtain the state and the control variables. In this technique, the FOC equations are reduced to Volterra type integral equations. The time domain is descretized into several segments and a time marching scheme is used to obtain the response at discrete time points. For a linear case, the numerical technique results into a set of algebraic equations which can be solved using a direct or an iterative scheme. The problem is solved for different number of eigenfunctions and time discretizations. Numerical results show that only a few eigenfunctions are sufficient to obtain good results, and the solutions converge as the size of the time step is reduced. The formulation presented is simple and can be extended to FOC of other distributed systems.
A Study of Orifice Compensated Multilobe Hole-Entry Hybrid Journal Bearing
Authors: Nagaraju T. , Basavaraja J. Sharana , Sharma Satish C. , Jain S. C.
Published: May 2009

The hydrostatic and hybrid journal bearings are finding increasing applications due to their excellent characteristics. The non-recessed hydrostatic/hybrid journal bearings have been developed so to provide an improved performance over the recessed/pocketed hydrostatic/hybrid journal bearings. The stability and unsteady behavior of the journal bearings is greatly influenced by bearing geometry, and accordingly various designs have been used by designers to achieve the desired objective. The non-circular journal bearings i.e. the multilobe journal bearing exhibits better stability as well as a superior capability to suppress whirl. In the present paper a theoretical study pertaining to a novel journal bearing configuration i.e. two-lobe hole-entry hybrid journal bearing is being presented. The work presented in this paper aims to study the performance of a two-lobe hole-entry hybrid journal bearing system compensated by a orifice restrictors. The Reynolds equation governing the flow of lubricant in the clearance space between the journal and bearing together with the equation of flow through an orifice restrictor has been solved using FEM and Galerkin’s method. The bearing performance characteristics results have been simulated for an orifice compensated non-recessed two-lobe hole-entry hybrid journal bearing symmetric configuration for the various values of offset factor (δ), restrictor design parameter (cS2) and the value external load (Wo). Further, a comparative study of the performance of a two-lobe non-recessed hole-entry hybrid journal bearing system vis a vis circular hole-entry symmetric hybrid journal bearing system have also been carried out so that a designer has a better flexibility in choosing a suitable bearing configuration. The simulated numerical results for the non-recessed two-lobe symmetric hole-entry hybrid journal bearing system with an offset factor (δ) greater than one indicates a significant improvement of the order of 30 to 50 percent in the values of direct stiffness and direct damping coefficients as compared to a circular symmetric hole entry hybrid journal bearing system. The results presented in the paper are expected to be quite useful to the bearing designers as well as for the academic community.
Construction and Testing of Radio-Controlled Power Augmented Ram Model
Authors: Matveev Konstantin I. , Malhiot Zachary J.
Published: May 2009

Heavy-payload Power Augmented Ram vehicles represent a new class of amphibious transportation means. In the static and low-speed operational regimes, these machines utilize a skirtless pressurized air cushion generated by front jet propulsors. In the high-speed motion, the aerodynamic lift augmented in ground effect becomes the dominant support. The construction of a small-scale radio-controlled Power Augmented Ram model is described. Results of initial static and self-propelled tests on solid surfaces are presented. Future research work and possible full-scale applications are discussed.
Composite Crash Box: Roll Wrap Fabrication and Dynamic Axial Crush Performance
Authors: Browne Alan L. , Johnson Nancy L. , Botkin Mark E.
Published: May 2009

A feature of many vehicles is a bolt-on, replaceable front end clip designed to protect the remaining structure in 0° to 30° frontal and offset crashes up to 15 km/hr (ECE-R42, European Danner (AZT), Allianze, VDS, or Thatcham Tests). The principle energy absorbing elements in such front clips are called crash or crush boxes. These are hollow cross section often tubular structures located between the bumper and the front ends of the lower rails. Previous studies of the dynamic axial crush response of carbon fiber reinforced composite tubes suggested that both the mass of the crash box and the amount of overhang of the front end clip could be reduced by switching from a metal to a carbon fiber reinforced composite crash box. The axial dimension of the crash box could theoretically be reduced because of the 20% reduction in stack-up exhibited by composite compared to metal tubular structures. The mass could theoretically be reduced because of the higher energy dissipation capability per unit mass of the carbon fiber composite and the shorter length that would be required. The initiative summarized in this paper was the roll wrapping portion of a one year program intended to prove out these benefits. Specifically, it encompassed the design, roll wrapping fabrication, and dynamic axial crush testing of a carbon fiber composite version of the crash box for a mid-size vehicle. All project goals were met. As first steps crush performance of the baseline Al crash box was determined and requirements were established for the geometry and crush force of the composite crash box, the needed crush force being 70 kN. To achieve the desired crush force levels while reducing mass by 20% compared to Al requires an SEA (specific energy absorption) on the order of 45. Crash box specimens manufactured with the roll wrapping process spanned a wide range of fiber architectures which were chosen based on findings of earlier crush tests of composite tubular specimens. Dynamic axial crush tests were then conducted on these specimens. Through these tests we were successful in identifying combinations of fiber type, fiber architecture, and tube wall thickness that simultaneously satisfied the multiple targets of high crush force, low stack-up (high crush efficiency), and reduced mass.
Axial Crush Drop Tower Testing of Hydroformed Sections
Authors: Mayer Robert R. , Webb Scott , Gusko Ruth , Williams Bruce , Worswick Michael
Published: May 2009

This report summarizes the drop tower testing of initially circular straight aluminum tubes that had been hydroformed to a square section with round corners. Drop tower test conditions and test setup were determined for the AlMg3.5Mn aluminum alloy circular (76.2 mm outside diameter) tubes of either 2.0 or 3.5 mm thickness, which had been hydroformed into a square tube with corner radii of 38.1 (unformed), 33, 30, 27 and 24 mm. To initiate test setup, theoretical equations were found to be reasonable indicators of displacement and load cell requirements. Four-lobe symmetric modes were found for the square tubes, and three-lobe asymmetric modes for the circular tubes. The number of folding half-waves of seven for 3.5 mm tubes, and thirteen for 2 mm tubes, was generally overpredicted by theory. Aluminum end plates that were welded onto the tube ends allowed for fast test setup, but may have resulted in some sliding and tipping of the drop tower. The tubes were found to have decreasing average crush force with smaller corner radii, esp. for the 3.5 mm thick tubes.
Engine Torque Control Based on Discrete Event Model and Disturbance Observer
Authors: Nagata Takashi , Tomizuka Masayoshi
Published: May 2009

This paper presents a novel control method for torque generation in four-stroke spark ignition (SI) engines. A model-based approach is employed to control engine torque output by adjusting throttle air intake with considerations of robust stability and performance. Discrete event engine model (DEM) is adopted with an addition of torque generation dynamics. Disturbance observer (DOB) techniques are utilized to achieve robust stability and performance by regarding the discrepancy between the actual plant and the nominal plant with desired plant characteristics as an equivalent disturbance input, which is estimated and cancelled. The desired plant behavior is stably realized by the DOB up to a bandwidth which is sufficient for a torque control application discussed in authors’ previous work. A switching scheme for desired nominal plant is proposed to further enhance robust performance and stability. Numerical results show the effectiveness of the proposed schem.
Optimal Power Management of Plug-In Hybrid Electric Vehicles With Trip Modeling
Authors: Gong Qiuming , Li Yaoyu , Peng Zhong-Ren
Published: May 2009

Hybrid electric vehicles (HEV) have demonstrated their capability of improving the fuel economy and emission. The Plug-in HEV (PHEV), utilizing more battery power, has become a more attractive upgrade of HEV. The charge-depletion mode is more appropriate for the power management of PHEV, i.e. the state of charge (SOC) is expected to drop to a low threshold when the vehicle reaches the destination of the trip. In the past, the trip information has been considered as future information for vehicle operation and thus unavailable a priori. This situation can be changed by the current advancement of Intelligent Transportation Systems (ITS) based on the use of on-board GPS, GIS and advanced traffic flow modeling techniques. In this paper, a new approach of optimal power management of PHEV in the charge-depletion mode is proposed with driving cycle modeling based on the historic traffic information for the highway portion and the traffic lights signals information for the local road portion. A dynamic programming (DP) algorithm is applied to reinforce the charge-depletion control such that the SOC drops to a specific terminal value at the final time of the cycle. The vehicle model was based on a hybrid SUV. Only fuel consumption is considered for the current stage of study. For the local road part, a trip modeling scheme was developed based on the synchronization with the traffic signals. Simulation study was conducted for several standard driving cycles, and then for an example trip. The results showed significant improvement in fuel economy compared with a rule-based control and a depletionsustenance control for most cases. The benefit of using traffic signal in trip modeling was also revealed from the improved fuel economy.
Improvement of Transmittable Torque of CVT Using Hybrid V-Belt Under Lubricated Condition
Authors: Asahi Takayuki , Okubo Kazuya , Fujii Toru , Sakanaka Hiroyuki , Kido Ryuichi , Takahashi Mitsuhiko
Published: May 2009

The purpose of this study is to show the effective method to increase the transmittable torque for continuously variable transmissions (CVT) using hybrid block V-belts under lubrication. The influence of belt geometry on the maximum transmittable torque of CVT was discussed while four types of belt were used, having different dimensions of either upper or lower arms of H-shaped blocks. The effect of lubrication between the belt and the pulley on the transmittable torque was investigated based on the Stribeck curve in order to examine the change of frictional state of contact surface and the power transmitting efficiency. The micro-grooving technique was also applied to the CVT blocks to obtain the high transmittable torque and stable lubrication. The test results suggested that the maximum transmittable torque was expected at a high belt velocity condition if the positive projection of the tension members exists for CVT even under the lubricating condition. The lubricant state between the belt and the pulley should be divided into three modes based on the Stribeck curve; boundary lubrication mode, mixed lubrication mode and hydrodynamic lubrication mode. Both higher transmittable torque and power transmitting efficiency are achieved if the boundary lubrication mode is kept. The micro-grooving technique applied to the contact surface of the blocks also contributed to increase the maximum transmittable torque for CVT using hybrid V-belts when CVT was operated at high belt velocity.
Development of a Steer Tilt Controller for a Three Wheeled Tilting Vehicle
Authors: van Poelgeest Auguste , Edge Kevin A. , Darling Jos
Published: May 2009

A three wheeled tilting vehicle called CLEVER was developed at the University of Bath. The tilt mechanism of this vehicle consisted of two hydraulic actuators that tilted the cabin in response to the driving conditions. Although this system was reliable, it had high power requirements, so a different method was needed. One way in which such a vehicle could be tilted was using the same principle that a motorcycle rider applies to tilt his bike, namely countersteer. This type of tilt control was expected to reduce the power required to lean. First, the vehicle and a basic steer controller were modelled. The simulations showed that the steer controller balanced the vehicle well, but deviated significantly from the intended path. A controller that could combine both the balance and the path following function was required. A good controller for this task is clearly the driver, so a pilot study was launched where the steering inputs of various drivers were measured. This study was carried out using a three wheeled tilting moped. The results of this study showed that the frequency of the steering inputs depended on the driver’s experience and the more experienced the driver, the lower the frequency of steer input for a given manoeuvre. The steady state manoeuvre showed that all drivers achieved a lean angle depending on the speed and turning radius in compliance with the theory. The countersteer was difficult to determine, because the drivers shifted their weight to aid the tilting. This indicated that countersteer is dependent on the driver and the driving conditions. However, a correlation between the countersteer and the countersteer rate was found, showing that either little countersteer could be applied for a short time, or a lot of countersteer could be applied for a short time. Another correlation was found between the countersteer rate and the maximum tilt acceleration, where the larger the countersteer rate, the larger the tilt acceleration. Since the tilt acceleration was related to the lateral acceleration, these correlations could aid the development of a steer tilt controller.
Utilization of Vehicle Dynamic Simulations as Predictors of Highway Safety
Authors: Brennan Sean N. , Hamblin Bridget C.
Published: May 2009

Safety is a crucial consideration in the design of roadways, yet formal tools to study roadway safety prior to construction are often quite limited. As a possible new tool, this work investigates the iterative use of vehicle dynamic simulations to study vehicle-roadway interaction in order to optimize highway design for safety. Following a discussion of the history and accuracy of vehicle dynamic simulations, a methodology of roadway geometry analysis is presented. This methodology is demonstrated by an example scenario studying the safety of a depressed median of a rural highway when there is an in-median incursion. The vehicle type, vehicle speed, vehicle trajectory, and the driver’s corrective maneuvers are all varied in a simulation-based analysis to evaluate their respective effects on vehicle behavior including vehicle orientation, trajectory, and instabilities.
Lessons Learned From Matching Experimental Data to Low-Order Models of Vehicle Behavior
Authors: Brennan Sean N. , Hamblin Bridget C.
Published: May 2009

This work presents “lessons learned” from an ongoing experimental and simulation investigation of vehicle chassis dynamics. The overall goal of this work is to find low-order physics-based models that are easily fitted from experimental data, yet accurately describe vehicle chassis motion in yaw, sideslip, and roll angle. In previous work related to this effort [5], anomalies in the model were found where key tire parameters, specifically the cornering stiffnesses, exhibit different best-fit values depending on whether the vehicle is tested in swept sine frequency responses or curvilinear steadystate motion such as skid pad maneuvers. The first portion of this work summarizes these results. Next, new research is presented investigating the source of cornering stiffness discrepancies. The tire modeling errors are found to be very strongly related to vehicle roll angle, and from this insight, corrections to the simple chassis models are derived to allow inclusion of a roll dependency in the tire model. Additionally, during investigation of this advanced tire model, terrain disturbances were found to be significant. A method to remove terrain effects is proposed and demonstrated. Comparing these roll- and terrain-corrected fits to results from prior work [5], the new model gives a significantly improved fit in the frequency domain, and outstanding fit in the time domain.
Controller-Observer Implementation for Cycle-by-Cycle Control of an HCCI Engine
Authors: Ravi Nikhil , Roelle Matthew J. , Gerdes J. Christian
Published: May 2009

This paper presents experimental cycle-by-cycle control of a single cylinder HCCI engine. The controller is developed from a discrete-time nonlinear model presented in previous work. The model captures the behavior of a gasoline direct-injection engine with an exhaust-recompression strategy used to achieve HCCI. This model is linearized about an operating point so as to enable the synthesis of linear controllers. The model states are represented by the temperature and oxygen content of the retained exhaust, and so are not measurable in practice. Therefore, an observer is used to estimate the states based on a measured ignition proxy. The state estimates are then used by a reference-input tracking controller to track a desired system trajectory. Experimental results show tracking of the model outputs that is comparable to tracking achieved in simulation. The controller is also seen to reduce the cycle-to-cycle variability of combustion significantly, particularly at later combustion phasing. This stabilizes combustion, lowers the instances of misfires, and enables steady operation at points that are normally unstable.
Estimating Thermodynamic State and Ignition in HCCI With Variable Fuel Injection Timing
Authors: Roelle Matthew J. , Ravi Nikhil , Gerdes J. Christian
Published: May 2009

Homogeneous charge compression ignition (HCCI) combustion timing depends on properties of gas in the cylinder such as temperature and composition. However, these properties are extremely difficult to measure. In this work, we present a method to estimate the thermodynamic state in order to map ignition timing for exhaust-recompression HCCI. Viability is demonstrated on four experiments. To capture the effect of fuel that is injected into recompressed combustion products, the method begins with a hypothesis of recompression reactions. From an initial guess, the method deterministically updates the chemical composition estimate in the cylinder over combustion, exhaust, recompression reactions and induction. The update function is based on incylinder pressure measurements, the ideal gas law and the first law of thermodynamics. The estimates are compared to measurements of inducted air and exhaust oxygen concentration to check the original hypothesis. Finally, the estimated thermodynamic state is correlated to combustion timing to produce a rich ignition map.
Gain-Scheduled Control for an Automotive Traction PEM Fuel Cell System
Authors: Al-Durra Ahmed A. , Yurkovich Stephen , Guezennec Yann
Published: May 2009

To be practical in automotive traction applications, fuel cell systems must provide power output levels of performance that rival that of typical internal combustion engines. In so doing, transient behavior is one of the keys for success of fuel cell systems in vehicles. From a model-based control perspective, regulation of the fuel cell system through transients is critical, where the response of a fuel cell system depends on the air and hydrogen (flow and pressure regulation) and heat and water management. The focus of this paper is on the air/fuel supply subsystem in tracking an optimum variable pressurization and air flow for maximum system efficiency during load transients. The control-oriented model developed for this study considers electrochemistry, thermodynamics, and fluid flow principles for a 13-state, nonlinear model of a pressurized fuel cell system. For control purposes, a model reduction is performed by converting some of the model dynamics to simple algebraic relationships. A single reference input, the power demanded by the user, is utilized to produce a corresponding reference air flow and back-pressure valve opening, after passing through a static calculation and a tabulated map. Because of the complexity of the full nonlinear model (used in simulation as the truth model), where several maps are used rather than functional forms, two different control techniques are examined separately, each using a feedforward component. The first technique uses an observer-based linear optimum control which combines a feed-forward approach based on the steady state plant inverse response, coupled to a multi-variable LQR feedback control. An extension of that approach, for control in the full nonlinear range of operation, leads to the second technique, nonlinear gain-scheduled control.
Reduced Order ARIMA Models of 2-D Terrain Profiles Using Singular Value Decomposition
Authors: Wagner Shannon M. , Ferris John B.
Published: May 2009

The terrain profile is the principal source of vertical excitation to a vehicle’s chassis. To correctly predict the system response an accurate model of the terrain is needed. It is impractical to simulate long data sets; therefore it is necessary to characterize roads so that they can be grouped into sets with similar physical characteristics. The first step is to consider the road to be a realization of an underlying stochastic process. This work develops a method for characterizing non-stationary terrain profiles though ARIMA (autoregressive integrated moving average) modeling and singular value decomposition techniques. It is proposed that the ARIMA coefficients and the distribution of the residual process are jointly dependent functions of the physical characteristics of road profiles. This dependence is then exploited by mapping these dependent functions onto a smaller set of random variables. The resulting number of coefficients required to characterize the terrain is greatly reduced. Examples demonstrate that non-stationary road profiles can be characterized in this manner. Future work in polynomial chaos and ARIMA modeling are discussed within the context of terrain characterization.
Real-Time, Open-Loop Estimation of Disturbance Inputs to a Quarter-Car Model
Authors: Ziegnemeyer Jon , Southward Steve
Published: May 2009

A real-time open-loop estimator is proposed for predicting the dynamic road input and the external force acting on a quarter-car vehicle. This estimate is achieved using only two acceleration measurements as inputs to the estimator; one each on the sprung and unsprung masses. The proposed method is differentiated from current disturbance accommodating control and bilinear observers. A description of the quarter-car model and the experimental test rig is given. Using the acceleration measurements from the quarter-car test rig, LTI model parameters were optimized for use in the estimator. The measured and estimated tire disturbance input, disturbance input velocity, and dynamic tire force signals are compared between simulated and experimental tests. The results show that the open loop observer provides estimates of the tire disturbance velocity and dynamic tire normal force with acceptable error.
Extreme Response Predictions for Jack-Up Units in Second Order Stochastic Waves by FORM
Authors: Jensen Jo̸rgen Juncher
Published: May 2009

The aim of the present paper is to advocate for a very effective stochastic procedure, based on the First Order Reliability Method (FORM), for extreme value predictions related to wave induced loads. All kinds of non-linearities can be included, as the procedure makes use of short time-domain simulations of the response in question. The procedure will be illustrated with a jack-up rig where second order stochastic waves are included in the analysis. The result is the probability of overturning as function of sea state and operational time.
Numerical Model to Simulate Tensile Wire Behavior in Unbonded Flexible Pipe During Bending
Authors: Zhang Yanqiu , Qiu Lun
Published: May 2009

The tensile wires in flexible pipe play an important role for forming the axial strength and stiffness of the pipe and for supporting the pressure armoring wires to resist the internal pressure. In the meanwhile, the fatigue life of the flexible pipe is generally often limited by the tensile wire life because the stress variations in the wires are considerably greater than those in other metal layers of the pipe. Therefore, exactly understanding and evaluating tensile wire behaviors are significantly important and necessary. In other words, as long as the behaviors of tensile wires can be evaluated the working mechanism of pipe bending can be evaluated.
Study of Typhoon Disaster Zoning and Prevention Criteria Along Coasts of China: A Type of Double Layer Nested Multi-Objective Probability Model and Its Application
Authors: Liu Defu , Liu Yuzhong , Pang Liang , Xie Botao , Wu Yuankang
Published: May 2009

For prevention and mitigation of typhoon disaster in China, in this paper the double-layer nested multi-objective probability model of typhoon disaster zoning and prevention criteria is proposed. The Multivariate Compound Extreme Value Distribution (MCEVD) is used to predict the joint probability of seven typhoon characteristics and corresponding typhoon induced disaster. Predicted results can be used for both of typhoon disaster zoning and corresponding prevention criteria along China coast.
What Is the Optimum Size for a Wind Turbine?
Authors: Moe Geir
Published: May 2009

Wind turbines have grown tremendously during the last 20 years and it is of interest to investigate how large they can be expected to be. In the present paper several structural aspects have been studied in order to see how they develop as a function of size. It was found that as long as thrust and centrifugal forces dominate, then most aspects of the turbine are independent of scale, provided geometric similarity scaling is performed. The most important deviation from this rule is that selfweight of the blades results in stresses that grow linearly under geometric scaling. The effects of selfweight appear to become important for the largest machines currently available. (5MW)
Influence of Longitudinal Members Partially Missing to the Operative Vessel Residual Strength Calculations for Emergency Response Service
Authors: Egorov Gennadiy V. , Nilva Alexandr E. , Solovyov Andrey A.
Published: May 2009

In accordance with up-to-date IMO requirements it’s necessary to create shore organizations that are able to carry out damage stability and residual structural strength calculations for a damaged vessel. The paper is based on simple elastic analysis to calculate the residual strength of the damage vessel under various damage scenarios.
Flexible Riser Response Induced by Springing of an FPSO Hull
Authors: Vidic-Perunovic Jelena , Nielsen Niels J. Risho̸j , Zhang Haiwen
Published: May 2009

The hydrodynamic analysis of the flexible riser for offshore application is usually limited to the first order wave frequency motions of the floating vessel that holds the riser top end. In this paper effort is made to investigate the influence of non-linear second order springing deflection of the production vessel hull on flexible riser response. The system selected in this study consists of a free-hanging flexible riser configuration attached to an FPSO. Due to resonance between the excitation wave frequency and the natural vibration frequency of the hull, second order flexible vertical motions of the FPSO increase. This may influence the riser loads, presumably the tension force. Vertical motions including the second order high frequency contribution are assigned to the flexible riser at a point of attachment to the vessel. To account for the environmental loading, irregular sea is applied, characterized by modified linear wave spectrum. Second order excitation wave spectrum is truncated by use of WAFO routines for random second order wave simulation and an analytical form of the spectrum that accounts for the non-linear wave effects is proposed. Several environmental conditions are examined in order to consolidate the tendency in riser behaviour. The significance of the high-frequency quadratic terms in the loads along the flexible riser is discussed.
Review of Measured Full Scale Ice Loads to Fixed Structures
Authors: Bjerka˚s Morten
Published: May 2009

This paper gives a review of selected public available full scale measured ice forces to fixed structures. Altogether 31 data sources are collected where the highest ice load, a current ice thickness and a structural width is reported. The main emphasis of this study is to formulate an engineering tool to predict upper bound ice forces to structures with a low number of input parameters available. Typical applications will be in early phases of projects for estimations of costs and technical integrity of surface piercing fixed structures in ice infested oceans and rivers.
Weight Optimized SCR: Enabling Technology for Turret Moored FPSO Developments
Authors: Foyt Elizabeth , Griffin Cary , Campbell Mike , Wang H. Howard , Kan Wan C.
Published: May 2009

Steel catenary risers (SCRs) used in conjunction with a turret moored FPSO in deepwater environments present significant design challenges. The large vertical motions at the FPSO turret induce severe riser response. This results in difficulty meeting strength and fatigue design criteria at the Touch Down Point (TDP) and at the riser hang off location. It is typically considered challenging to achieve feasibility for a conventional SCR application on a turret moored FPSO. Previous industry work for an SCR application used with other floating hosts has demonstrated that SCR strength and fatigue response can be improved using heavy and light coatings strategically placed along the riser [1]. An optimization study is performed, based on previous industry work, which demonstrates that a weight optimized configuration can enable the application of an SCR on a turret moored FPSO. The effect of adding different coatings along the length of the SCR is discussed. The position, length, and density of the coating type are varied to determine an optimum configuration for both strength and fatigue response. This paper will also discuss observations which may help explain why weighted sections can improve SCR response at the critical area.
TN X SN Fatigue Curves for KS Hook and Chain Using Finite Elements Modelling and Model Test
Authors: de Almeida Jose´ Carlos Lima , Rossi Ronaldo Rosa , Sobral Ricardo
Published: May 2009

The new scenario of oil exploration in ultra deep water moves forward to 3000 m, has been putting for the companies that accept this technological challenger significant, border of the techno-scientific knowledge. Therefore, nowadays in this case of ultra deep waters, where the forces above the mooring lines are increase and the use of the new material in Petrobras Floating Production Units, it is necessary the good numerical analyses and experimental test by the mooring line. It appears the need to look for a solution for the problems according to the changes of the polyester rope in the production platform without the bottom extension change and its foundation (fixed point). According to this challenge it was necessary to develop a remote connection and disconnection device. This device is the KS hook and its optimization has been created using the fracture mechanical conception optics and computers tools (FEM and mooring software). There are two conditions to develop this device: one condition is functional and the other is structural. For the functional condition, it’s necessary to create the facilities for handling and installations. For the structural conditions, it is necessary to use the special wrought steel material, treatment for steel characteristic and right geometry. Finite Elements Modeling analyze used the Ansys software, considered the hardness profile material for Minimum Break Load (MBL). The lifetime design is about 25 years for this case and the fatigue analysis considered the residual stress and plasticity for structural device. Previous simulation is especially important in predicting behavior and in the development of new design products before testing. The model was meshed with 3D first order tetrahedral elements solid45. The mesh was sufficiently fine to ensure minimal loss of accuracy in curved geometry. There isn’t a TN fatigue curve (reference API Fatigue curves) for this KS Hook device geometry, in this case become necessary to use the model test to obtain this curve with the extrapolation of the results. The Finite Elements Modeling analyze used with the Material SN Fatigue curve will be used for this validation. Previous simulation is especially important in predicting behavior and in the development of new design products before testing.
Second Order Wave Generation Technique in the Laboratory
Authors: Zaman M. H. , Mak L.
Published: May 2009

Correct generation of the primary waves and the reproduction of the group-induced second-order low and high frequency waves have been considered essential for physical model test in the laboratory to understand the effects of the wave-action phenomena on, for instance, offshore structures, mooring system, LNG, other floating vessels, harbor resonance, etc. When natural waves are reproduced, the primary waves and their locked bounded waves are generated along with some unwanted free waves. Those free waves are evidently generated and propagate towards the test model and reflect from the boundaries. The free waves, having the same frequency of the bounded wave are reproduced due to mismatch of the boundary conditions at the wave paddle. The other two types of free waves are due to the wave paddle displacement and the local disturbances. The so-called second-order wave generation technique could eliminate these alleged free waves. In this experiment second-order wave generation technique is successfully used to reproduce the correct bounded waves along with elimination of the unwanted free waves from the wave profiles. This experiment is implemented by means of compensating free waves imposed on the system by second-order paddle motion. The control signal for this motion has to be introduced along with the primary waves. An extensive experimental works are carried out in the Offshore Engineering wave Basin (OEB) at the Institute of Ocean Technology (IOT), NRC to investigate the quality and the characteristics of the generated primary waves and their locked bounded waves when the unwanted free waves are eliminated. The measured results are then compared with the predicted results. Two different water depths are used within the shallow water limit. The obtained results are also compared with the numerical predictions.