bluuebunny/crossref_metadata_2025 huggingface dataset:
Background Noise Definition for Acoustic Emission Leak Monitoring System at GTP Molve
Authors: Hudec Goran , Muvrin Boris
Published: January 2009

In Croatian Podravina relatively large quantities of natural gas was discovered. From various fields (Molve, Kalinovec, Stari Gradec) natural gas is pipelined to Gas Treatment Plant (GTP) Molve. Here, at GTP Molve III, technological procedures for purification of natural gas and its distribution are performed. With yearly natural gas production of 3,5 109 m3 GTP Molve III is major Croatian energy resource. Its safety and environment impact is matter of concern. Continuous acoustic emission leak monitoring system for Gas Treatment Plant (GTP) Molve as an improvement in technological and environment safety is considered. Application of a leak monitoring system under industrial conditions is a problem setting specific demands. In the paper attention is paid to some aspects of acoustic emission system implementation and the acoustic background noise definition problem. Acoustic noise measurements at a GTP Molve III were performed and some results considering background noise are presented. In the paper acoustic noise measurements performed at a GTP Molve III were presented. Across the GTP Molve III acoustical background have different spectral and amplitude characteristic. In the input area, measurements presented at a first group of measuring points included the impact of sand moved by gas fluid. Sand hits should be distinguished from acoustic emission caused by growing cracks. Motors noise and turbulence around valves are probably the main source of background noise on second group of measuring points. The conclusion is that background noise across the plant is highly different. Patterns found in one part of plant could not be applied on others measuring points. Background noise and its characterization are one of main problems solved before reliable operation of acoustic monitoring system could be applied. It is found that at GTP Molve III acoustic background is complicated, consisting of different sources at different part of a plant.
Use of Offshore Drilling Waste in Hot Mix Asphalt (HMA) Concrete as Aggregate Replacement
Authors: Wasiuddin N. M. , Ali Nouman , Islam M. R.
Published: January 2009

Despite continuous research and development on drilling fluids and waste minimization during the last 40 years, offshore drilling waste (OSDW) remains a significant environmental concern for the petroleum industry. OSDW contains three types of contaminants namely, heavy metals from drilling fluid, oil from oil based mud or petroleum contamination and naturally occurring radioactive substances from exposed formations. In this study a promising and permanent solution based on recycling of OSDW as road construction materials has been investigated. It has been revealed previously that five to ten percent of some waste materials such as recycled asphalt pavement, tire rubber, glass, roofing shingles, polythene etc. can be added to hot mix asphalt (HMA) concrete without sacrificing its strength and performance. These wastes can be added to the HMA by either replacing the mineral filler or proportionately reducing the amount of virgin material in the original mix. In this laboratory test study, different percentages of OSDW were added as aggregate replacement and the properties of resulting blends were evaluated. Three beneficial actions, namely, incineration, dilution and solidification took place. At the end, the effectiveness of using OSDW was determined with the Marshall stability and flow, permeability of HMA concrete, leachability and resilient modulus. It has been found that for the drilling waste used in this research the percentage that can be used in HMA concrete without sacrificing its properties is as high as 20%. Even though the percentage of waste that can be used as aggregate replacement varies with waste types and properties, the proposed technique offers significant promises for OSDW recycling.
Effect of Inlet Configuration on Flow Behavior in a Cylindrical Cyclone Separator
Authors: Erdal Ferhat M. , Shirazi Siamack A.
Published: January 2009

The use of Gas-Liquid Cylindrical Cyclone (GLCC©) separators for gas-liquid separation is a new technology for oil and gas industry. Consequently, it is important to understand the flow behavior in the GLCC© and effect of different geometrical configurations to enhance separation. The main objective of this study is to address the effect of different inlet configurations on flow behavior in the GLCC© by measuring velocity components and turbulent kinetic energy inside the GLCC© using a Laser Doppler Velocimeter (LDV). Three different inlet configurations are constructed, namely: one inclined inlet, two inclined inlets and a gradually reduced inlet nozzle. Axial and tangential velocities and turbulent intensities across the GLCC© diameter were measured at 24 different axial locations (12.5” to 35.4” below the inlet) for each inlet configuration. Flow rates of 72 and 10 gpm are selected to investigate the effect of flowrate (Reynolds number) on the flow behavior. Measurements are used to create color contour plots of axial and tangential velocity and turbulent kinetic energy. Color contour maps revealed details of the flow behavior.
Development of High Pressure Composite Butt-Weld Joint
Authors: Li Guoqiang , Pang Su-Seng , Jones Randy J. , Hale Mark , McCurry Ben T. , Schmit Kevin
Published: January 2009

There is currently a need to develop high pressure composite butt-weld joint to meet the needs of deepwater activities. In this study, a tapered butt-weld composite joint configuration was proposed. Finite element analysis was conducted to validate the proposed structural configuration through stress-strain distribution analysis. Test samples were assembled using hand lay-up technique. The prepared specimens were hydro tested. The test results justified the proposed joint configurations. About 35.7% increase in bursting pressure in tapered butt-weld composite joint was observed over currently used composite butt-weld joint.
Shear Strength Characteristics of an Ultrasonic Welded Lap Shear Joint
Authors: Ibekwe Samuel , Mensah Patrick F. , Jana Amitava , Li Guoqiang , Stubblefield Michael A.
Published: January 2009

Experimental attempts were carried out on ultrasonically joining glass fiber composite materials using fiber reinforced adhesive. Two sets of specimens with different energy guides were investigated. All the samples failed by shear at the interface of the lap joint. Finite element analysis was conducted to justify the test results and the effect of adherend surface treatment.
Enhancement of Composite Sucker Rods for Use in the Oil Industry
Authors: Woldesenbet Eyassu
Published: January 2009

Analysis of polymer-matrix composite sucker rod systems using finite element methods is performed. Composite sucker rods fail mainly due to fatigue loading. In majority of cases, the failure is in the region of the joint where the composite rod and the steel endfitting meet. 2D and 3D Finite Element Analysis and experimental tests are carried out in order to observe the stress distribution and to find the regions of stress concentrations inside the endfitting. The causes of fatigue failure of the composite sucker rods are identified. These are overloading of the rod causing high transverse compressive stress that results crushing of the rod, and high stress concentrations present at the grooves of the endfitting that initiate premature fatigue cracks. Based on the result of this study, enhanced design of the composite sucker rod system can be accomplished.
A Mathematical Model to Overcome the Discrepancies Between Continuous Systems and Their Discrete Approximation
Authors: Singh Kumar V. , Ram Yitshak M.
Published: January 2009

The classical finite element and finite difference formulation in structural dynamics leads to an algebraic eigenvalue problem whereas the continuous model however leads to a transcendental eigenvalue problem. This paper demonstrates the discrepancies between continuous systems and their discrete approximations and, introduces a finite dimensional transcendental eigenvalue method, which approximates the spectrum of the continuous system accurately. Illustration of the effectiveness and applicability of such a model has been shown with an example of an axially vibrating tapered rod.
A Top Ten List of Guideposts to Help Prepare for a Project Negotiation
Authors: Voivedich Ben E.
Published: January 2009

Given a negotiating life cycle that includes preplanning, formal planning, performing the negotiation, and post negotiation review, this paper is oriented toward project team members without formal negotiation training that are looking for easy-to-follow “guideposts” to pre-plan and get ready for negotiations with vendors, business unit representatives, and other project stakeholders. The guidepost, or checklist, items are meant to serve as: a “mental launching pad” for an upcoming negotiation or as an organizer for the planning of a larger full-blown negotiation.
Dynamic Response of a Pipe Having Bolted Flange Connection With a Gasket
Authors: Semke William H. , Bibel George D. , Gurav Sanjay B. , Webster Adam L. , Jerath Sukhvarsh
Published: January 2009

In this paper the effect of a bolted joint on the dynamic response of a pipe will be presented. The problem is analyzed both experimentally and by computer modeling. Standard 2-in. (51mm) Schedule 40 steel piping with a Class 300 RFWN flange is used. The pipe is used as a simply supported beam at its ends with a 14.5-ft (4.42 m) span. It is connected at the midspan by two flanges, with or without a gasket, and high strength bolts. The gasket used is a flexible spiral wound steel gasket of 0.180in. (4.57mm) thickness. Two values of pre-tensioning, 25,000 psi (172.5 MPa) and 50,000 psi (345 MPa) are used in the high strength bolts connecting the two flanges. Experimental values of fundamental frequency are comparable to the values obtained by computer modeling. It is found that the presence of the gasket and the loading exerted by the bolts on the flanges had very little effect on the fundamental frequency of the pipe system.
VIV Predictions for an SCR in Sheared Ocean Currents
Authors: Wajnikonis Christopher J.
Published: January 2009

Vortex Induced Vibration (VIV) prediction is one of the key areas of interest in Deepwater Riser Engineering. Several Joint Industry Projects (JIPs) are currently in progress in this field, which results in an increase of experimental data available to design engineers, in revisions of specialized software and in development of new engineering tools. This paper presents VIV predictions for a hypothetical Steel Catenary Riser (SCR) using the latest versions of the SHEAR7 and the VIVA/VIVARRAY Programs. Both built-in and extended program capabilities are utilized and detailed plots of computation results are presented. Sensitivity studies on the influence of variations of selected design parameters are also included in the paper. Finite Element Analyses (FEAs) results and simple engineering tools were utilized in parallel to built-in program features. The calculations demonstrated, that for the riser investigated and presumably also for a wide variety of similar SCRs, that the built in program features are sufficient to predict VIVs conservatively. Notes on VIV predictions in a real ocean and on selected areas that require investigation are also included.
Pressure Testing of Airport Underground Aviation Fuel Hydrant With Jet A-1 Fuel on Completion of Construction
Authors: Clearwater Barry
Published: January 2009

The paper is a description of the author’s experience in the pressure testing of airport underground fuel hydrants with aviation kerosene type fuel, Jet A-1. The paper will discuss pressure testing codes, useful and practical proof (strength) test and leak test acceptance criteria. Equipment to be used for the measurement of test pressures and temperatures will be discussed. Problems and advantages with testing with fuel will be covered. Interpretation of leak detection results by correlating pressure test response with temperature measurements and presentation of the concept that the trend is more important than the absolute values of pressure and temperature will be covered. Promotion of the idea that research is needed into the sensitivity of leak detection. The author has experience in the pressure test in a variety of fuel hydrants, but most recently with the fuel hydrant at the new Hong Kong International Airport at Chek Lap Kok, Hong Kong.
A Method for Planning and Performing a Pressure Survey to Achieve Desired Accuracy of Pressure Gradient
Authors: Hebert Joel J.
Published: January 2009

This paper describes a method for planning a pressure survey (a series of pressure, depth measurements), and for using a pressure survey tool, so that the user can predict in advance the number of pressure tests needed to be performed in a pressure survey such that the resulting pressure gradient will be accurate within a desired standard deviation. It further describes a method and process for performing a pressure survey, including measuring pressure gradient and standard deviation thereof for downhole fluid bearing formations, using information collected from pressure survey apparatus, such that the requisite amount of information is collected to ensure the measurements actually received are within the desired standard deviation. There is a patent pending in the U.S. Patent Office for the technology described herein.
Avoiding Pitfalls in Multiphase Thermo-Hydrodynamic Coupling
Authors: Ayala Luis F. , Eltohami Eltohami S. , Adewumi Michael A.
Published: January 2009

Multiphase flow is prevalent in many industrial processes. Therefore, accurate and efficient modeling of multiphase flow is essential to the understanding of these processes as well as the development of technologies to handle and manage them. In the petroleum industry, the occurrence and consequence thereof associated with such hydrodynamic processes are encountered in offshore facilities, surface facilities as well as reservoir applications. In this paper, we consider the modeling of these processes with special consideration to the transport of petroleum products through pipelines. Multiphase hydrodynamic modeling is usually a trade-off between maximizing the accuracy level while minimizing the computational time required. The most fundamental modeling effort developed to achieve this goal is based on applying simplifications to the basic physical laws, as defined by continuum mechanics, governing these processes. However, the modeling of multiphase flow processes requires the coupling of these basic laws with a thermodynamic phase behavior model. This paper highlights the impact of the techniques used to computationally couple the system’s thermodynamics with its fluid mechanics while paying close attention to the trade off mentioned above. It will consider the consequences of the simplifications applied, as well as inherent deficiencies associated with such simplifications. Special consideration is given to the conservation of mass as well as the terms that govern its transfer between the phases. Furthermore, the implications related to the common simplification of isothermal conditions are studied, highlighting the loss of accuracy in the material balance associated with this computational time-saving assumption. This paper concludes by suggesting remedies to these problems, supported by results, showing considerable improvement in fulfilling both the basic constrains which are minimizing time and maximizing accuracy.
Phase Re-Distribution and Heat Transfer in Gas/Condensate Flow Shut-In in a Deepwater Lazy-Wave Riser
Authors: Chin Y. Doreen , Krishnathasan K. , Roberts I.
Published: January 2009

The mechanisms of phase re-distribution of gas/condensate flow in a deepwater steel lazy-wave riser after system shutdown have been studied numerically. The investigated system consists of a 15-mile long subsea pipeline tieback to a floating vessel, via a 9,800-ft long lazy-wave production riser. The subsea well is located at 6,350 ft of water. The system is insulated, and transports a gas-condensate mixture with liquid loading of 10 stb/mmscfd. This study reveals that besides pressure, the internal heat transfer during system cool-down is a key factor for the phase re-distribution between gas and liquid, and along the system. The liquid holdup variations are caused by the interfacial mass transfer between gas-liquid interface and phase re-distribution due to the combined effects of gravitational and buoyancy forces. Fluid cool down temperature “overshoot” in the lazy wave riser valley during system cool down has been observed. The pressure effect on the cool down temperature overshoot has been studied. The phenomenon is discussed based on fundamental heat transfer, phase equilibrium, and multiphase flow principles. The lazy wave riser configuration is a promising option for deepwater development, and gas/condensate flow is a multiphase flow phenomenon commonly encountered in raw gas transportation. The results of this study improve the understanding of multiphase flow transient behavior in deepwater pipeline/riser systems, and benefits gas/condensate production system design.
Thermodynamic Model of a Twin-Screw Multiphase Pump
Authors: Nakashima Celso Yukio , de Oliveira Ju´nior Silvio , Caetano Elisio F.
Published: January 2009

The twin-screw multiphase pump has been studied as an alternative system to substitute the conventional one (fluid separation, liquid pumping and gas compression) in petroleum boosting. By “pumping” simultaneously gas and liquid, the multiphase pump could reduce production costs in deepwater activities. This paper presents a thermodynamic model of a twin-screw multiphase pump to determine performance parameters such as: absorbed power, discharge conditions and efficiency. To overcome problems with the complex flow field inside of this novel equipment, the multiphase flow was divided into a sequence of simpler processes. Such approach helps determine energy and mass balances and enables the use of a process simulator (Hysys.Process v2.1) to construct the model. The model prediction when compared to the literature show that the assumption of a smooth turbulent flow, considering the pressure loss in the entrance and discharge of the gap, fits better the phenomena than the turbulent flow when calculating the flow through the gaps. In addition, the comparison for absorbed power indicates that the assumption of gaps filled only with liquid is not valid under all operation conditions.
Analysis of Coupling Between Axial and Torsional Vibration in a Compliant Model of a Drillstring Equipped With a PDC Bit
Authors: Elsayed M. A. , Raymond David W.
Published: January 2009

In this paper, we discuss results of rock drilling tests at Sandia National Laboratories’ Hard Rock Drilling Facility (HRDF). The HRDF incorporates a drillstring with axial and torsional compliance and is equipped with a coring bit having PDC (Polycrystalline Diamond Compact) cutters. We measure and analyze chatter and show evidence of stick-slip as well as coupling between axial and torsional vibrations. We show the coupling signature in axial vibration data in the form of side bands indicating frequency modulation at the torsional natural frequency. The influence of operating conditions on the bit response is shown.
Studies Toward the Development of a Continuous Position Monitoring and Discontinuous Repositioning System of a Motorway Bridge
Authors: Danieli G. A.
Published: January 2009

A two-part electronic system was designed to monitor and maintain the alignment of a bridge which is to be constructed in clay terrain. Previous bridges constructed along this Motorway in Southern Italy were closed for beam misalignment resulting from pillar displacement. The current two-part system was developed to provide a means to continuously monitor the position of the pillars and restore deck-pillar realignment when pillar displacement is detected. The monitoring system measures relative pillar position using a new multiple laser system. The repositioning system is composed of a number of computer controlled mechanical actuators bearing six degrees of freedom. A hydraulic piston coupled to a ring nut gear will be used for lifting, and will hence be intrinsically safe, since this configuration will not allow retrograde motion in case of power failure. Each actuator will allow motion along three perpendicular directions and spherical rotation about a point, to permit rotations of the bridge beams with respect to the pillars during deck-pillar realignment.
Proposal of a Bridge Deck Displacement Continuous Measuring Device and Periodical Realignment System Designed to Minimize Traffic Interruptions
Authors: Danieli G. A. , Fragomeni G. , Mundo D. , Vigna M.
Published: January 2009

The paper presents the most recent developments on electronic bridge control applied to a bridge located along a southern Italian Motorway in an area where a landslip is in slow yet continuous motion. A previous bridge was closed for beam misalignment caused by the landslip action. A new bridge was recently designed with much sturdier foundations, but even during the initial construction phases it was evident that a static solution was undesirable, if not impossible. Jet, based on the observations of the last twenty years, the foreseen movements are relatively small, 20 cm being the maximum horizontal measured displacement in that period. A further version of the bridge has thus been proposed, characterised by lighter and longer decks, in order to negotiate the section with fewer elements. Moreover, the monitoring and repositioning systems have been thoroughly redesigned, to allow an almost continuous adjustment of the bridge decks, severely limiting the realignment times, in order to reduce traffic interruptions. A reduced number of interferometric lasers have been used, using rotating drums with mirrors individually preset to sweep the entire measuring field. The lifters, in their present version, should substitute the props, being used as active connections between pillars and decks, thus being able to support all traffic induced dynamic stresses in the vertical direction. The lifters have also been made sturdier eliminating all ball bearings in favour of teflon sheets. In addition, computer controlled lateral supports have been added to the system, allowing to move the deck horizontally while transmitting traffic or hearth-quake shocks to the pillars. On the top of each lifter an elastic interface bearing strain gauges will enable the measurement of tangential stresses as well as uneven distribution of the load, providing further information on the need of beams realignment.
Force Vibration Analysis of Thick Beams on Two Parameter Elastic Foundation by Finite Element Method
Authors: Bahcivan Ali , Karadag Vedat
Published: January 2009

In the present work, the free vibration analysis of rectangular cross-section uniform beams on two-parameter elastic foundation, considering shear deformation and rotatory inertia is made by the finite element method. In this analysis, two different thick beam elements are used. The first 4 degrees of freedom thick beam element has two nodes with two degrees of freedom at each node such as transverse displacements and cross-section rotations. In the second beam element, the nodal variables are the transverse displacement, the cross-section rotation and shear deformation. The elastic foundation is idealized as a constant two-parameter model characterized by two moduli, i.e., the Winkler foundation modulus k and the shear foundation modulus kG. In the case kG = 0, this model reduces to the Winkler model, i.e., the elastic foundation is idealized as a constant one-parameter model. Axial displacement of the beam is also considered. Three kinds of end conditions, i.e., simply-supported, clamped-clamped and clamped-free ends are considered in this study. The effects of axial force, foundation stiffness parameters and partial elastic foundation on the natural frequencies of the beam are examined. In this analysis, the vibration calculation results are presented in the tables and their importance in design are discussed. The numerical results obtained from this analysis are compared with the exact or available solutions, wherever possible. Numerical results and comparisons show the effectiveness of the proposed method.
Theoretical Analysis of Fatigue Strength of a Double-Deck Bus Body Using FEM
Authors: Ereke I. Murat , Yay Kubilay
Published: January 2009

Modern design techniques primarily consist of finite element analysis of the vehicle body in a computational media. In this study, an actual double-deck bus body of domestic production has been modeled in three-dimensions by means of IDEAS program in order to calculate its fatigue strength. In other words, an approximation algorithm has been developed to obtain service loads. The effects of dynamic and static loads on the bus body have been calculated and included to the FEM analysis. As a new approximation technique, during the service life of a vehicle under dynamic loads (straight good road, straight bad road, cornering bad road and singular obstacle road) arising from the road conditions as taking into account, load spectrum has been constituted. In the design spectrum that has been utilized in our calculations, considering the equivalence damage effect rule, instead of using straight good road conditions, other fifty percent of forces that have been mentioned above, accepted as hundred percent of dynamic and static forces caused by bad road conditions acting on the bus body. As a result of this study, the calculated results have been compared to the theoretical and experimental data taken from literature review. It can be seen that this approximation technique that we used in our calculations can be used for this kind of fatigue analysis of vehicle components or bodies.
Force Control of a Robot Arm During Contact Task
Authors: Yetik A. , Karadag V.
Published: January 2009

There are extremely important applications to investigate the control of contact between the end-effectors and the object. During controlling an object, static or in motion, the robot arm should not be damaged. Forces are important in such conditions. The forces between the end-effectors and the object have to be controlled. The motion of the robot arm changes forces. Thats why, to control forces, a force kontrol algorithm must be developed. Previous conventional force control algorithms could not control the robot effectively by only considering the variation of working environment. In this study, a control algorithm strategy to achieve the desired interactions forces between the robot end-effector and the environment during contact tasks, has been developed. The surface of the object and robot are very stiff, thus contact spring coefficient Kc is very large, because of this Kc effect, the results of the forces simulation results, but we get suitable results. Study include, modelling robot arm, evaluating measured forces during contact and constructing a suitable force control algorithm, dynamics, kinematics and simulation results. In this study, we used impedans control which the surface of the object is very stiff, as known as impedance control does not try to track position and force trajectories directly, but rather to regulate the dynamic relationship between the contact forces and manipulator positions, namely the mechanical impedance. Impedance control focused on the design of a robot’s dynamic behavior as seen from the environment. In this control strategy, no hardware or software, switch is needed in the robot’s control system when the robot travels from the free motion space to the constrained space. The force feedback loop closes naturally as soon as the robot interacts with the environment, which changes the robot’s impedance as seen from the environment. By controlling the manipulator positions, and regulating their relationship to the contact forces, the manipulator can be controlled to maintain appropriate contact forces.
Neuro-Fuzzy Active Control of Mechanical Structures
Authors: Couzon Pierre-Yves , Der Hagopian Johan , Gaudiller Luc
Published: January 2009

The abilities of neural networks combined with fuzzy logic offer interesting prospects for the active control of structures. By identification, they permit discarding the often delicate modeling step and they also permit the automatic regulation of the controllers that have non-linear characteristics. This study describes the application of neuro-fuzzy control to the dynamic behavior of structures. The study first explains the process chosen, which consists of two parts: • the first part is essential for the adjustment of the associated controller and concerns the neural identification of the structure studied; • the second part describes the controller development and the training stage; the controller is based on the simplest neural network model possible. This network is also able to translate Sugeno’s fuzzy function and optimize its performances according to a reference response. The study then presents two applications: the first deals with the identification and control of a linear mechanical system with two degrees of freedom. The second deals with the identification and control of the non-linear dynamic behavior of active electromagnetic actuators along one acting axis. In both cases, the results show the abilities and the efficiency of this process and underline the main advantage of this type of controller operating even on in a strongly non-linear system.
Data Reducing in Machine Diagnostics With Neural Networks
Authors: Lumme Veli Erkki , Tervokoski Janne
Published: January 2009

The paper presents a method to collect and save only relevant data from a machine. The data can be used for training the system to identify running situations that have already occurred in the monitored machine or similar types of machines. This method can be used to give direct notice or alarm in a control room with clear indication of the problem. Modern software development tools, like Java for instance, offer new technologies for operation monitoring of machines. The system can be accessed via Internet using common browsers. The paper presents practical experiences in the application of the method. It demonstrates, how the system will adapt into various environments and running situations. The method presented in this paper is applied in operation monitoring of machines, but it can be also used for other monitoring purposes.
Vibration Isolation of a Test Bench Founded on Sand Layer
Authors: Kivinen Juha-Matti , Keskinen Erno , Hildebrand Robert , Ja¨rvinen Ville
Published: January 2009

A modern paper machine is equipped with various finishing units e.g. calendars and coating units to produce better optical and printing properties. Today’s trend is to supply these finishing units with polymer covered rolls. Tampere University of Technology (TUT) has built up an experimental set-up to study both vibration phenomena and polymer behavior. One of the essential task is to determine and verify the soil-machine interaction. This paper presents the preliminary analysis of the vibratory behavior and experimental results of modal analyses.
Diagnosis of Heat Leveler by Vibration Signature Monitoring
Authors: Salmenpera¨ Pekka , Miettinen Juha , Ma¨a¨tta¨ Tapio
Published: January 2009

A heat leveler machine can create valuable economical losses in fault situations. By applying on-line monitoring of the vibration signatures, the machine can be followed continuously and the changes in the process and in condition of the mahcine can be detected immediately. The on-line monitoring consists of the on-line adjustment of drive parameters as well as quality control. Generally several kinds of different sensor types are applied into the system. On-line monitoring of rolling bearings usually includes vibration measurement sensors. A heat leveler operates at differnt speeds and loads and the direction of process can be reversed during run. The reliability of the results of the on-line monitoring can be increased by measuring simultaneously different parameters that influence on the vibration of the machine. This method is called multi-parameter monitoring. This paper focuses on the possibilities of on-line monitoring of the support bearings in a metal slab heat leveler by vibration measurements. The leveler is equipped with vibration sensors of low frequencies as well as high frequency acoustic emission sensors. The main issue is experimenting different kind of signal processing methods and optimal procedures are then programmed to the on-line monitoring computer. The measurements in this study were performed in industrial circumstances, in a steel mill. The test machine was a heat leveler machine in normal industrial usage. A method of varying limit values is presented. For this, acoustic emission and acceleration rms-signals are applied. Values are determined by the forces in the leveling cylinders. Forces correspond to the deformation resistance of the steel plates.
Intercalation of Layered Double Hydroxide Polymer Nanocomposites
Authors: Hudson C. Monica
Published: January 2009

Magnesium-aluminum (Mg-Al) based layered double hydroxide (LDH) polymer nanocomposites were developed through the implementation of a rehydration technique. Organic anionic surfactant sodium dodecyl sulfate (SDS) and an anionic polymer, poly(styrene sulfonate) (PSS) were used for intercalation in the cationic intergallery spacing of LDH. This rehydration technique was performed by calcination of the LDH precursor for removal of carbonate anion followed by rehydration of organic anionic phase in a nitrogen rich atmosphere. The resulting nanocomposites were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and powder x-ray diffraction (XRD).
Machining Al2O3/6061Al Metal Matrix Composites Using Coated Tungsten Carbide Inserts
Authors: Sadat Abdul B.
Published: January 2009

An experimental procedure is used to machine 20 vol.% Al2O3/6061Al metal matrix composites using coated tungsten carbide cutting inserts in a finish turning operation. The turning operations were carried out at various cutting speeds and feed rates, at a constant depth of cut, and with the application of a coolant. Tool wear lengths at two locations, at the flank of the primary cutting edge and at the flank of the nose of the tool were measured for each cutting test after the removal of a predetermined volume of material. It was found that the wear lengths at both locations of the tool increased with a decrease in feed rate due to the increase in cutting time as the feed rate decreased. It was also found that for a given speed and feed rate the wear on the flank of the nose was higher than that of the primary cutting edge. This was attributed possibly to the presence of the built-up edge on the rake face of the tool. Surface roughness, generally, increased with an increase in cutting time that was explained in terms of an increase in nose wear length as the cutting time was increased.
An Independent-Flow-Field Model for SDOF Nonlinear Structural System: Part I — Identification and Comparisons
Authors: Yim Solomon C. S. , Lin Huan
Published: January 2009

An independent-flow-field (IFF) model selected in this study to investigate the nonlinear response behavior of a medium-scale, experimental, submerged, moored structure is validated via parametric studies. Bifurcations in experimental responses are frequently observed and the associated nonlinear primary and secondary resonances are identified in frequency response diagrams. Distinct from previous investigations, this study intends to identify a set of “best-fit” constant coefficients for predictions and comparisons over the entire wave frequencies examined. It is concluded that the small-body, IFF model predicts reasonably well the nonlinear, moored and submerged structural response subjected to regular waves.
Risk Analysis of Running a Deepwater Production Test From a Dynamically Positioned Vessel in the North-Atlantic
Authors: Maes Marc A. , Sinclair Jeff , Lewis David B.
Published: January 2009

The present paper describes the key steps and issues involved in performing a quantitative risk analysis (QRA) for a dynamically positioned (DP) offshore vessel that is used to perform a short-term production test (PT) in North Atlantic deep waters. The basic approach is to focus on the “incremental” risk that would occur if the PT were run from a DP vessel as opposed to a fixed structure. The analysis is structured around two basic groups of risk: those specifically associated with DP vessel disconnection decisions and activities (all of which are seasonal) and those occurring during normal operation of the DP vessel. In the case of disconnection caused by hazards such as severe weather, ice, equipment or reference system malfunction, or human/operating error, a large variety of event sequences is assumed, each resulting in different consequences and risks. These are formulated for each analysis outcome in terms of loss of life, release of chemicals into the environment, damage and loss of assets and equipment, as well as overall failure cost. It is shown that the QRA provides a very useful basis for optimal decision making with respect to the feasibility, the planning, and the risk/benefit of deep-water production testing from a DP vessel.
Numerical Simulation of Vortex-Induced Vibration on a Circular Cylinder
Authors: Wanderley Juan B. V. , Levi Carlos A.
Published: January 2009

The Vortex-induced vibration on a circular cylinder is investigated by the numerical solution of the unsteady Navier-Stokes equations and results are compared with experimental measurements obtained by different authors. The Beam and Warming implicit factored scheme is used to solve the governing equations and Large Eddy Simulation is used together with the Smagorinsky subgrid-scale model (SGS) to simulate the turbulent flow in the wake of the cylinder. The cylinder is laterally supported by a spring and a damper and is free to oscillate in the transversal direction in an initially uniform flow for the first flow speed investigated. For the subsequent speeds, the final condition obtained for the previous speed is used as initial condition to reproduce the actual experimental set up. In that case, the measurements are done by progressive increments of the flow speed retaining the fluid memory effect. The complexity and high sensitivity of the flow phenomenon at this configuration requires a very accurate and robust numerical model. Most of the known algorithms failed to duplicate the available experimental measurements. The proposed numerical solution was able to provide a good picture of the real physics of the phenomenon showing the Ka´rma´n vortex street effects on the lift and drag coefficients. The numerical results for the transversal oscillation amplitude are compared to experimental data showing a fairly precise agreement at the difficult to simulate regime of the lock-in phenomenon.
Application of a Discontinuous Galerkin Method to 1-D Liquid Sloshing
Authors: Guillot Martin J.
Published: January 2009

A discontinuous Galerkin method is applied to the shallow water equations written in a rotating frame of reference. Linear approximating functions are employed on each element. A minmod slope limiter is incorporated to ensure non-linear total variation bounded (TVB) stability. The method is first applied to the dam breaking problem with zero rotation to validate the numerical implementation. A rotating tank is then investigated with sinusoidal rotation. Results are computed with and without slope limiting to investigate the effect of slope limiting on the solution. The DG method is also compared to a first order Godunov method and to experimental data.
A Numerical Study on Hydrodynamic Interactions Between Large Numbers of Multiple Floating Bodies
Authors: Inoue Yoshiyuki , Ali Mir Tareque
Published: January 2009

This paper investigates the hydrodynamic interactions between large numbers of multiple bodies floating in each other’s close vicinity. The physical aspect of hydrodynamic interaction is rather complicated and numerically sound scheme is highly recommended to study this complex phenomenon. In the present study, the 3D sink-source method has been adopted to determine the hydrodynamic forces by taking into account the effect of hydrodynamic interactions among the different floating bodies, and the coupled equations of motions are solved directly. The validation of the computer code developed for this purpose has been justified by comparing the present results with that of the published ones for simple geometrical shaped floating bodies. The numerical computations have been carried out for different numbers of various freely floating multi-body systems and the hydrodynamic interactions between the floating bodies have been studied by calculating the hydrodynamic forces, first order wave exciting forces and motion responses. Finally some conclusions have been drawn on the basis of the present analysis.
Jacket Reliability Design Considering Interacting Limit States
Authors: Ronalds B. F. , Pinna R. , Ryan S. P. , Riordan J. A. , Radic T. M. , Cole G. K. , Bea R. G.
Published: January 2009

The reliability of jacket structures is addressed by considering inter-relationships between ultimate strength, fatigue and progressive collapse limit states, for both intact and damaged structural configurations and a range of defect and collapse events, including accidents and gross errors. Simple robustness criteria for use in design are suggested based on the ratio of damaged-to-intact probabilities of failure, a progressive collapse indicator and damaged strength ratio (DSR) values. Their practicality is illustrated by detailed reliability assessments of two quite different jacket structures — a major 6-leg platform and a shallow water tripod. The strong interdependence between robustness and quality requirements is demonstrated, as is the potential importance of fatigue-driven progressive collapse for certain structures.
A New Approach for Dynamic Reliability Analysis of Offshore Platforms
Authors: Jin Wei-Liang
Published: January 2009

The theoretical framework of a new dynamic reliability analysis approach for offshore jacket platforms is constructed in this paper. In this approach, the structural dynamic reliability analysis integrates the structural dynamic response theory with the random sampling technique on stochastic variables of the platform. Offshore jacket platform is assumed as a shear type one and is controlled by its horizontal resistance bearing capacity. The failure criterion of offshore platform dynamic reliability includes two aspects: strength failure criterion and deformation failure criterion. The strength failure criterion is based on the double-damage criterion of ultimate dynamic analysis, while the deformation failure criterion depends on the requirement of the offshore oil production. The dynamic reliability formula of offshore platforms is gained on the basis of the first crossing theory. In this paper, uncertainties of offshore jacket platform dynamic reliability subjected to wave hydrodynamic and seismic action are studied respectively. The probabilistic distributions and its statistical characteristics of wave hydrodynamic and seismic action are given on the base of limit bearing state of the platform. The dynamic reliability analysis of an offshore platform W11-4C, located at the gulf of Weizhou, South China Sea, is carried out. Some valuable conclusions are summarized.
Basic Strategy of Health Monitoring on Submarine Pipeline by Distributed Optical Fiber Sensor
Authors: Jin Wei-Liang , Shao Jian-Wen , Zhang En-Yong
Published: January 2009

Submarine pipeline system is a main pattern in collection and transmission of offshore oil and gas, which sends oil and gas from offshore oil/gas field to land, and it plays an important role in the production of oil and gas. Because of the complicated and harsh condition in which pipeline system works, such as impulsion, corrosion and free-spanning vibration, failure of submarine pipeline system occurs occasionally, it causes oil leakage, environment pollution and economic losses. Health monitoring is a feasible and effective manner to ensure submarine pipeline safe and reliable during service, especially when all factors affecting pipeline failure are not still entirely realized or controlled. The basic strategy of a new real-time monitoring system for long distance submarine pipeline is introduced in this paper, which has the function of diagnosis and auto-alarm. In this system, a new distributed optical fiber sensor (DOFS), which uses optical time domain reflectometry theory based on Brillouin backscatter, is applied to monitor the strain and temperature along the pipeline. To be used for long distance submarine pipeline, this system applies Wavelength Division Multiplex (WDM) technology and series DOFSs in series so as to extend the measure scope for long distance submarine pipeline. By using signal processing system to analyze the outcome data of sensor, the strain along the pipeline can be obtained. If the strain reaches the alarm setting, the system will send out caution and meanwhile accurately give the damage position. The system can also analyses vibration frequency of pipeline, if free-spanning vibration occurs, caution will also be given, so that the operator can take some measures in time to avoid the failure of pipeline. In this paper, the makeup of distributed optical fiber sensor and developing principle are specified, system development, application and construction in engineering are analyzed as well. The brand new practical system can not only be used for submarine oil and gas pipeline but also for land oil and gas transfer system, city coal gas transfer system, electricity-transmission cable and so on. This system can be widely used in many prospects of other industries.
Modeling of Floating Pneumatic Rubber Fender in Numerical Simulation of Side-by-Side Moored Vessels
Authors: Sakakibara Shigeki , Kubo Masayoshi
Published: January 2009

In this paper, we approach a modeling of the floating pneumatic rubber fender in the time domain numerical simulation of side-by-side moored vessels. In the investigations, we conduct several performance tests such as pure compression tests and compression with shear load tests for the miniature fender. From the investigations, it is concluded that it is necessary to consider the actual fender performance for the development of the numerical simulation method.