bluuebunny/crossref_metadata_2025 huggingface dataset:
Slope Error Measurements of Parabolic Troughs Using the Reflected Image of the Absorber Tube
Authors: Ulmer Steffen , Heinz Boris , Pottler Klaus , Lüpfert Eckhard
Published: January 2009

A new and fast method for optically measuring the reflector slope of parabolic troughs with high accuracy has been developed. It uses the reflection of the absorber tube in the concentrator, as seen from some distance, and is therefore called “absorber reflection method.” A digital camera is placed at a distant observation point perpendicular to the trough axis with the concentrator orientated toward it. Then, a set of pictures from the absorber tube reflection is taken with slightly different tilt angles of the concentrator. A specially developed image analysis algorithm detects the edges of the absorber tube in the reflected images. This information, along with the geometric relationship between the components, the relative collector tilt angles, and the known approximately parabolic shape of the concentrator, is used to calculate the slopes perpendicular to the trough axis. Measurement results of a EuroTrough segment of four facets are presented and verified with results from a reference measurement using high-resolution close-range photogrammetry. The results show good agreement in statistical values as well as in local values of the reflector slope. Compared to the existing photogrammetric method, the new technique reduces drastically the time measurement.
Speed and Direction Shear in the Stable Nocturnal Boundary Layer
Authors: Walter Kevin , Weiss Christopher C. , Swift Andrew H. P. , Chapman Jamie , Kelley Neil D.
Published: January 2009

Numerous previous works have shown that vertical shear in wind speed and wind direction exist in the atmospheric boundary layer. In this work, meteorological forcing mechanisms, such as the Ekman spiral, thermal wind, and inertial oscillation, are discussed as likely drivers of such shears in the statically stable environment. Since the inertial oscillation, the Ekman spiral, and statically stable conditions are independent of geography, potentially significant magnitudes of speed and direction shear are hypothesized to occur to some extent at any inland site in the world. The frequency of occurrence of non-trivial magnitudes of speed and direction shear are analyzed from observation platforms in Lubbock, Texas and Goodland, Indiana. On average, the correlation between speed and direction shear magnitudes and static atmospheric stability are found to be very high. Moreover, large magnitude speed and direction shears are observed in conditions with relatively high hub-height wind speeds. The effects of speed and direction shear on wind turbine power performance are tested by incorporating a simple steady direction shear profile into the fatigue analysis structures and turbulence simulation code from the National Renewable Energy Laboratory. In general, the effect on turbine power production varies with the magnitude of speed and direction shear across the turbine rotor, with the majority of simulated conditions exhibiting power loss relative to a zero shear baseline. When coupled with observational data, the observed power gain is calculated to be as great as 0.5% and depletion as great as 3% relative to a no shear baseline. The average annual power change at Lubbock is estimated to be −0.5%.
Lessons Learned From 25 Years of Friction Modeling
Authors: Soom Andres
Published: January 2009

We have long known that tangential contact forces and the friction coefficient at a sliding contact arises not due to some “law” but as a result of contact geometric and material properties in combination with physical processes that are not always accessible to direct experimental verification. While tribologists have occasionally sought alternatives to the coefficient of friction as the primary means to quantify tangential forces at sliding contacts, its convenience, simplicity, long history and lack of viable alternatives assure that it will be remain in use for some time to come. Sometimes the coefficient can remain constant with normal load over orders or magnitude. One can be led to believe that the coefficient is a property of the interface or there is a “law” at work. At other times, the coefficient, usually measured, is said to vary with time, sliding distance or some other variable with no explanation as to why the variation occurs. In the present paper we discuss aspects of friction behavior and modeling, focusing on mechanics and the nature of the friction coefficient. The point of departure is a case where the adhesion theory of friction can be used to understand the mechanics of friction. One can then consider a number of situations and concepts that arise as variations of this case including average versus instantaneous friction; cases when Amontons-Coulomb relations do or don’t apply; static versus dynamic friction; scale effects at rough surfaces; limits of applicability of the friction coefficient; friction measurements, thermal and velocity effects; and local versus global friction and constitutive relations.
An Experimental Investigation of Elastic Plastic Contact and Friction of a Sphere on Flat
Authors: Levinson Ofer , Etsion Izhak , Halperin Grigori
Published: January 2009

An experimental investigation is presented to evaluate recently published models for the contact and sliding inception of a deformable sphere loaded against a smooth rigid flat. The effects of the normal load on the contact area, junction growth, and the static friction force in the elastic-plastic contact regime are presented. Very good correlation is found between the predicted and measured contact area. A dramatic decrease of the static friction coefficient with increasing normal loading is observed, similar to the trend predicted by the model. The quantitative agreement is, however, less satisfying. Some possible reasons for the poor agreement are pointed out.
Stick-Slip Vibration Between Two Large Concentric Circular Discs in Rotational Contact With Multiple Point Loads
Authors: Baleri M. , Sassani F. , Ko P. L.
Published: January 2009

This paper presents a study of the stick-slip frictional phenomenon when large contact areas subjected to uneven contact loads are involved. The objective of the investigation is to gain better understanding of the phenomenon from experimental observations and to develop a mathematical representation that can be used for modeling, simulation and design purposes. A dynamic integral-model has been proposed and simulations have been carried out. The effects of various system parameters on the behavior of the system have been studied experimentally and analytically. The simulation results using the proposed integral-model are in good agreement with the experimental results. The latter also show that stick-slip vibrations can be influenced by the loading conditions.
Friction and Wear in the Presence of Fullerene Contained Lubricants at Boundary Conditions
Authors: Dubrovsky R. , Titov A.
Published: January 2009

This work describes application of fullerenes as additives for liquid lubricants such as motor oils. Experiments include dynamic tracking of friction coefficient and weight measurements of samples before and after experiments. Friction coefficient measurements have been done on computer-controlled wear-friction testing machine, which has been developed at Surface Engineering Laboratory in NJIT. For the proposed series of experiments, this machine employs conforming disc-on-ring arrangement of rubbing bodies at boundary lubrication; sample couple is steel AISI 4340 and bronze SAE 40; nominal contact pressure ranges from 1.9 MPa to 3.7 MPa with sliding speed of 0.61 m/s. Tested lubricants were prepared on the basis of super duty motor oil SAE 10 by adding one weight percent of additives: pure C60, mixture of C60 and C70 and graphite powder. Performance comparison of fullerene contained lubricants with pure oil and oil modified by graphite powder showed that although there is no any clear difference in friction coefficient value for tested lubricants, fullerene contained lubricants decrease wear rate of rubbing bodies.
Determination of Real Material Properties From Nanoindentation Experiments
Authors: Kogut L. , Komvopoulos K.
Published: January 2009

In recent years, due to extensive development of depth-sensing indentation techniques, nanoindentation has been used to evaluate the mechanical properties of surface layers and thin films of different materials. However, current nanoindentation procedures are based on simplified assumptions about the material behavior during unloading and empirical relations of the contact area (e.g., Oliver and Pharr, 1992) with little input from analytical and numerical solutions. Therefore, it is unclear what properties can be measured using instrumented nanoindentation techniques and what is the validity of the present procedures for measuring reduced elastic modulus and material hardness. Thus, the main objective of the present study was to analyze the validity of the current approaches for determining material properties and to propose an alternative approach for measuring the reduced elastic modulus, yield strength, and material hardness.
A Correlation Between Pressure Distribution and Bounding Surfaces in Elastic Contacts
Authors: Diaconescu Emanuel
Published: January 2009

Many authors attempted to establish a direct correlation between the equation of the surface of an equivalent rigid punch and the pressure distribution arising when this punch is pressed against a corresponding elastic half-space. The results are encouraging, but they have a limited applicability and the involved calculations are still complicated. This paper advances a simple correlation based on a new interpretation of integral condition of deformation of a contact and on the dependence of pressure or pressure gradient on singularities in surface gradient or curvature. Based on this correlation, a method to find the pressure distribution for contacts bound by surfaces described by up to second order polynomials is advanced. The new method is applied in several classical contact problems and a very good agreement is found with existing solutions.
Ultra-Thin Film Ultrasonic Characterization
Authors: Daugela Antanas , Blechertas Vytautas , Warren Oden L. , Kutomi Hiroshi , Wyrobek Thomas J.
Published: January 2009

Ultrasonically induced nanoscale fatigue and friction reduction phenomena are researched for nanometer order thick protective overcoats. The newly developed method described here is a synergy of the nanometer scale quantitative nanoindentation/scratch technique and ultrasonic excitation. A standing ultrasonic wave is generated at the sample holder during the quasi-static nanoindentation/scratch test at an excitation frequency of several hundreds of kilohertz. Due to the fact that high strain rates are being generated at the surface of the sample, nanofatigue phenomenon followed by delamination and overcoat chipping can be observed. Statistical investigation of fatigue inducing parameters, such as critical quasistatic load and amplitude of oscillations, leads to a means of comparative sample characterization.
A New Methodology to Evaluate the Rolling Contact Fatigue Performances of Bearing Steels With Surface Dents: Application to 32CrMoV13 (Nitrided) and M50 Steels
Authors: Ne´lias D. , Jacq C. , Lormand G. , Dudragne G. , Vincent A.
Published: January 2009

A new methodology is proposed to evaluate the rolling contact fatigue (RCF) performances of bearing steels in presence of surface dents. The experimental procedure consists in denting the raceway of the test specimen with a hardness machine using spherical diamond tips of different radius, i.e. 200, 400 and 600 μm, and normal loads ranging from 5 to 50 daN. Analysis of various dent geometries yields to an analytical law with five parameters useful to fit experimental profiles for contact simulation. Besides local residual stresses and plastic strains around the dent have been obtained by finite element simulations of the indentation process. RCF tests performed on a two-disk machine have shown better performances of nitrided 32CrMoV13 steel compared to M50 reference steel. The dominating role of sliding has been highlighted and two areas where damage initiates were identified, while the effects of the normal load and hoop stresses are less marked.
Theoretical and Experimental Investigations of an Elasto-Plastic Circular Contact Bounded by Real Rough Surfaces
Authors: Prodan Dorel , Diaconescu Emanuel
Published: January 2009

To investigate the pressure distribution and the stress state in a real elasto-plastic circular contact, bearing balls of two different degrees of surface finishing were used. These were pressed against a polished flat surface made of softer steel. The surface microtopography data measured in each case by a laser profilometry was introduced in a numerical program developed to evaluate the pressure distribution, stress state and residual deformations for an elasto-plastic material with non-linear hardening. The dimension of calculated contact plastic deformations compare favorably with those found experimentally by aid of a laser profilometer.
A Microactuator for Tracking Servo
Authors: Hirano Toshiki , Yang Henry , Pattanaik Surya , White Matthew , Arya Satya
Published: January 2009

To achieve higher data track density of a hard-disk drive (HDD), a microactuator that is placed between suspension beam and a slider and moves slider relative to suspension was investigated. This paper presents new microactuator design, “bipolar microactuator” and its performance in a hard-disk drive.
Identification of Stiffness and Damping in Collision of a Spherical Slider With a Magnetic Disk
Authors: Ono Kyosuke , Ohara Satoshi
Published: January 2009

This paper deals with experimental identification of the stiffness and damping in dynamic collision of a spherical slider with a magnetic disk. We used an Al2O3TiC spherical slider with a radius of 1mm and two kinds of magnetic disks whose substrate is Aluminum (Al) and glass. The Al disk samples have four different lubricant film thicknesses of 0, 1, 2, and 3 nm. In addition to the evaluation of the coefficient of restitution at collision, the velocity change of the slider from the beginning of penetration to separation from the disk is compared with the calculated motion of a slider based on Hertzian contact model and six different damping force models. As a result, we found that the elastic contact force due to penetrating depth can be accurately estimated by the Hertzian contact theory by use of elastic parameters in the substrate, whereas the damping force is proportional to the real contact area as well as the slider velocity. Moreover, the effective damping force factor is different between penetrating and repulsing processes of the slider. The damping factor in the repulsing process is more than two-orders larger than that of the penetrating process of the Al disk. The damping of glass disks is below noise level in both processes.
Dynamic Characteristics of Flying Head Slider Considering Van Der Waals Forces: Analyses Based on the Corrected Van Der Waals Force Equation for Multilayers
Authors: Matsuoka Hiroshige , Ohkubo Satoru , Fukui Shigehisa
Published: January 2009

A dynamic model of a simple inclined flying head slider was considered in order to analyze the dynamic characteristics of a flying head slider considering the van der Waals force the air bearing force. The corrected van der Waals force equation and the linearized molecular gas-film lubrication (MGL) equation were used for the analysis. The “spacing stiffness”, kspacing, composed of the stiffnesses due to the van der Waals force and the air bearing force was defined and the flying stability of the head slider was discussed. It was found that there are flyable limit minimum spacings, and relationship between the limit minimum spacing and the disk vibration frequency (the “boundary curve of dynamic flying stability”), which provides the boundary between the stable (kspacing > 0) and unstable (kspacing < 0) domains of the flying, was presented. The basic characteristics of the flying head slider considering the van der Waals force including the dependence of the boundary curve on the film thickness of PFPE lubricant were clarified.
Flying Height Deviation Measurements at Ultra Low Fly Heights
Authors: Kim Dongman
Published: January 2009

The flying height tester contribution to flying height tolerance is investigated with different calibration techniques in this study. The flying attitude change in head gimbal assembly (HGA) by supplying writing current is discussed along with newly proposed methodology for feature size measurement on the air bearing slider (ABS) using a flying height tester.
Electrical Breakdown in Electrostatic Fly Control
Authors: Schnur Deborah S. , Song Dian , Hipwell Roger L. , Boutaghou Zine-Eddine , Weinstein Robert E.
Published: January 2009

As areal density increases and fly height decreases in hard disc drives, it becomes more difficult to achieve a reliable flying interface between the recording head and the disc. Manufacturing variations, environmental conditions and other factors can cause mechanical spacing losses. One method to compensate for these losses is to control slider clearance using electrostatic force. An attractive force between the slider and the disc can be generated by grounding the disc and applying voltage to the entire slider body or a dedicated electrode. If the applied voltage exceeds the breakdown voltage of the head-disc interface (HDI), however, the resulting current flow will cause damage to the head and disc and ultimately cause the head to crash. A series of experiments were performed on flying heads and a MEMS small-gap tester to determine the nature of the current flow and the effects of head coatings and disc lubricant on breakdown voltage. The results support field emission as the current flow mechanism. In addition, a thick diamond-like carbon (DLC) coating on the slider or electrode increases breakdown voltage and may prove to be an enabler for electrostatic fly control. In comparison, lube appears to have only a secondary effect on electrical breakdown.
The Transient Development of Natural Convective Flow Due to Liquid Evaporation Within a Vertical, Open Cylindrical Enclosure
Authors: Bunama R. M. , Karim G. A.
Published: January 2009

Composition and temperature induced natural convection within an open topped vertical circular enclosure has been numerically investigated. A theoretical model that describes the mass, heat and momentum transport processes in a 2-dimensional axisymmetric domain is presented. The model included consideration of the transient development of natural convection flow, density and thermophysical property variations. The results presented are for a n-Pentane liquid vapor diffusing into Air. A description of the transient temperature and concentration gradients development is given along with their effects on the flow field progression.
Aspect Ratio Effects of Elliptic Co-Flow on Turbulent Jet Flame Structures
Authors: Choudhuri Ahsan R. , Luna Sayela P. , Gollahalli S. R.
Published: January 2009

The aspect ratio effects of elliptic co-flow on the structure of a turbulent propane diffusion flame from a circular tube have been presented. Pollutant emission, flame radiation, flame structure, and soot concentration have been measured. The fuel jet exit Reynolds number is 2700, and the exit Reynolds number for the co-flow is 4010 and 8025 based on the minor and major axis respectively. The results are compared with the measurements from the experiments in a circular co-flow, which is the baseline condition for the present study. The pollution characteristics and the structure of the flame in the elliptic co-flow are significantly different from those in the circular co-flow. The NO emission is higher and the CO emission is lower in the elliptic co-flow. Elliptic co-flow flame produces less soot than circular co-flow flame. The study shows that the elliptic co-flow aspect ratio has a controlling influence on various combustion characteristics. In general, it is seen that as the aspect ratio of the elliptic co-flow is increased from 2:1 to 4:1, the entrainment of air increases and thus the combustion characteristics are enhanced. Compared to 2:1 AR co-flow flames, the flames with 4:1 AR co-flow are more stable, have a lower flame height, produce more NO and less CO, the flame peak temperature is higher, are less sooty, and radiate less. Flame spectral measurements show that the 4:1 aspect ratio flames produce more OH, CH, C2 and H2O radicals in the near-burner region than the 2:1 co-flow flames as a result of higher fuel oxidation.
Modelling and Simulation of PEM Fuel Cells With CO Poisoning
Authors: Baschuk Jeffrey J. , Li Xianguo
Published: January 2009

A polymer electrolyte membrane (PEM) fuel cell has been analyzed by applying the conservation principle to the gas channels, electrode backings, catalyst layers and polymer electrolyte. The conservation equations used are conservation of species, momentum and energy and the Nernst-Planck equation in the electrolyte. Oxygen reduction at the cathode is modeled using the Butler-Volmer equation while the adsorption, desorption and electro-oxidation of hydrogen and CO at the anode are modeled by the Tafel-Volmer and “reactant-pair” mechanism, respectively. Comparison of the anode electrochemical kinetics model to experimental data indicates that CO adsorption kinetics are Temkin. One-dimensional simulation of a PEM fuel cell operating with reformate fuel gas indicates an optimum operating pressure. Preliminary two-dimensional simulation verifies the one-dimensional assumption for mass transfer but indicates that a two-dimensional analysis is necessary for the catalyst layer.
Performance of a Co-Fired Boiler Burner With Water Injection
Authors: Annamalai K. , Chen C. J. , Thien B. , Sweeten J.
Published: January 2009

A Co-firing technology with coal:biomass blends is expected to reduce land application requirements for manure based biomass wastes, and provide a renewable, low cost, and zero net fossil based CO2 fuel. The choice of low BTU biomass fuels may include conventional agricultural or unconventional animal based biomass fuels depending upon local availability and transportation costs. For power plants located near feedlots where cattle are fattened for slaughter, the best choice of renewable biomass fuel is feedlot manure, properly referred to as feedlot biomass (FB). Coal can be mixed with FB in a 90:10 (coal:FB) ratio by mass and fired in existing boiler burners. A 30 KW (100,000 BTU/hr) boiler burner facility was built and tested for firing coal or coal-FB blends at Texas A&M University. FB has a moisture content ranging from 20% to 40% moisture, but most of the previous data have been generated using low moisture FB (<10% moisture) due to problems processing moist manure. The current work will investigate the effect of different moisture levels using external water injection. The boiler burner was modified with an air atomizing water injector. At a fixed equivalence ratio and swirl number for the secondary inlet air stream, the effect of different moisture levels and different biomass particles on boiler performance was investigated. NOx, O2, and CO profiles along the axis of the furnace were obtained. The effect of atomizing air on the co-firing performance was also investigated. The results are summarized as follows: just with atomizing air is the wter injector, the NOx concentrations increased from 350 ppm to 650 ppm while CO decreased from 46,000 ppm to 18,000 ppm. External water injection decreased the NOx pollutant emissions from 570 ppm (zero external water) to 300 ppm (40% water in FB), but increased CO emissions from 2,500 ppm (zero external water) to 10,500 ppm (40% water in FB) due to incomplete combustion. Smaller sized particles of FB in the blended fuel produced less NOx but more CO.
Lift-Off, Reattachment and Blowout Limits of Co-Flow Jet Diffusion Flames
Authors: Karbasi M. , Wierzba I.
Published: January 2009

The stability behaviour of jet diffusion flames in a co-flowing stream of air was examined. Their lift-off, reattachment and blowout limits were established for methane, propane, ethylene and hydrogen. The co-flowing air stream velocity affected significantly the mechanism of flame stabilization. Different flow regimes where the blowout of lifted flames or attached flames can occur were recognized. A transition region in which both the blowout of lifted flames as well as that of attached flames was observed and identified with respect to the value of the air stream velocity. It was found that the blowout limits for lifted flames in this region were much smaller than for the attached flames. The effects of changes in the nozzle geometry and co-flowing stream composition were also considered.
Excess Enthalpy Flames
Authors: Babkin V. S. , Wierzba I. , Karim G. A.
Published: January 2009

Combustion processes with excess enthalpy are described with examples given. It is shown that different processes, such as heat and mass transfer, phase and chemical changes are involved. Moreover, flames with excess enthalpy can be encountered in a variety of forms such as laminar or turbulent, within homogeneous or heterogeneous systems involving stationary or unsteady processes, with pulse or spin combustion and as cellular flames. It is to be shown that mainly due to the increase in the chemical reaction rates within the combustion zone, the excess enthalpy state can lead to substantial increases in the burning rates, widening the associated flammability limits and modifying the preignition processes. Some applications that can benefit from the use of such flames are outlined.
Microscopic Studies of Syntactic Foams Tested Under Three-Point Bending Conditions
Authors: Gupta Nikhil , Woldesenbet Eyassu
Published: January 2009

Use of syntactic foam as core material in the sandwich structured composites is increasing due to its higher compressive strength, damage tolerance and low moisture absorption compared to the open cell structured foams. Extensive microscopic examination of the syntactic foams tested under compressive and three-point bending conditions is undertaken in this study. The aim of the investigation is to determine the local fracture mode and correlate it with the microscopic structure of the material. Local stress states are identified in the material based on the microscopic fracture features. Syntactic foam tested in the study has resin to microballoons ratio of 1.52 by weight. Compression tests were conducted on the syntactic foam specimens having two different aspect rations, which were 0.4 and 0.91. Three-point bend tests were conducted on the sandwich structures containing syntactic foam as core material and glass fabric as the skin material.
Investigation of the Manufacturability of Smart Composite Piping Structures Using Life Cycle Cost Modeling and Uncertainty Analysis
Authors: Maharsia Rahul R. , Jerro H. Dwayne
Published: January 2009

FRP composites are finding increasing use in the civilian applications such as highways, bridges, pipes etc. This analysis focuses on the FRP piping systems used in the Petrochemical industries under extreme conditions. Due to the high operational and maintenance costs involved with pipes made from traditional materials, there is a need to develop a smart inspection system that replaces or eliminates the traditional inspection and maintenance techniques, providing continuous and reliable monitoring of the structure. Smart FRP pipes have an embedded smart sensor system incorporated in them, providing continuous and reliable monitoring of the pipe structure. This helps in preventing catastrophic failure of pipes thereby reducing the costs involved with the pipe failure. Smart FRP systems have a very high initial investment cost, and therefore a cost comparison model is needed in order to justify their use against traditionally used materials. A Life Cycle Cost (LCC) comparison model has been developed in this paper, which shows that despite high initial investment costs, large savings could be made in the operational and maintenance costs with the use of Smart FRP pipes. This cost model Calculates the life cycle costs of Steel, FRP and Smart FRP pipes, and determines the alternative with the lowest life cycle cost. To deal with an uncertainty associated with the cost factors, used in calculating the LCC of the three alternatives, an uncertainty analysis has been performed. An computer spreadsheet has been programmed in order to perform the LCC and Uncertainty Analysis. This analysis has laid down the basic foundations for a larger cost model, wherein; several other alternatives materials and factors could be included. This would further help in widening the scope of use of Smart Structures in various industries. Certain aspects of the data used in this analysis may be disputable, however for the purpose of modeling and procedural demonstration, the gathered and available information was used to perform our analysis. Therefore, use of this data outside of the scope and context of this report is not warranted.
Finite Element Analysis of Adhesive-Bonded Single-Lap Joints
Authors: Yang Charles , Guan Zhidong , Tomblin John S. , Sun Wenjun
Published: January 2009

Finite element analyses were conducted using commercial software ABAQUS to analyze the mechanical behavior of single-lap adhesive-bonded joints. Adhesive was characterized for the stress-strain relation by comparing the apparent shear-strain relations obtained from finite element analysis and experiments following ASTM D 5656 “Standard Test Method for Thick-Adherend Metal Lap-Shear Joints for Determination of the Stress-Strain Behavior of Adhesives in Shear by Tension Loading.” With the established stress-strain relation, two failure criteria using equivalent plastic strain and J-integral were used to predict the failure load for joint specimens following ASTM D 5656 and ASTM D 3165 (Strength Properties of Adhesives in Shear by Tension Loading of Single-Lap-Joint Laminated Assemblies), respectively. Bondline thicknesses of 0.013”, 0.04”, 0.08”, and 0.12” were used in the investigation. Good correlation was found between the finite element results and the experimental results.
A Study of Joining of Different Melting Point Materials by Charging With Electromagnetic Energy
Authors: Haneji T. , Miyagi K. , Sueyoshi T. , Nakao Z. , Sakugawa K. , Yara H. , Ushio M.
Published: January 2009

An electrical resistance welding method was applied under atmospheric conditions by using one of metal powder medium or media mixture which was sandwiched in the space between the two solid metal bars of specimen (i.e., solid specimen material), and was compressed longitudinally by oil pressure servo control electrodes (upper and bottom) and simultaneously current was conducted to generate Joule thermal heat. In the joining experiments, a solid aluminum specimen material was used as a basis material, and was joined to another solid aluminum specimen material or one of four other solid specimen materials with different melting points by using resistance-welding apparatus. Some fundamental data on the mechanical properties of the joint were obtained by material testing. In the experiments, the specimen used as solid specimen materials in this study were pure aluminum, copper, stainless steel, carbon steel and titanium bars of solid specimen, and the powder media were aluminum, nickel and silicon powder. Proper mixed ratios of total amount of the powder media were determined for reliable joining, and material testing was prepared for mechanical properties. The obtained data were examined with the intent of optimizing the method using metal powder media between a pair of specimen materials and were compared with that of the solid specimen material, in terms of tensile strength, Vickers hardness, bending U-shape flexure stiffness. On the tensile strength and Vickers hardness, they were found to be reliable, but on bending U-shape flexure stiffness, they were not definite enough.
Torsional Vibration of an External Circular Crack in a Transversely Isotropic Composite
Authors: Tsai Y. M.
Published: January 2009

The forced torsional vibratory motion of an external circular crack in a transversely isotropic composite is investigated by using the method of Hankel transforms. A pair of vibratory torques of equal amplitude is applied at infinity. The infinite integral involved is evaluated through a contour integration to be discontinuous in nature. An exact expression for the dynamic stress intensity factor is obtained in terms of the frequency factor and the anisotropic material constants. The maximum value of the normalized dynamic stress-intensity factor is shown to occur at different frequency factors for the sample fiber-reinforced and metal matrix composites. The distortion of the dynamic crack surface displacement from the associated static displacement depends also on the forcing frequency and the material anisotropy.
Using Torsion Bar Testing to Determine Fracture Toughness of Ceramic Materials
Authors: Wang J. A. , Liu K. C. , Joshi G. A.
Published: January 2009

A new method, designated as Spiral Notch Torsion Test (SNoTT), is introduced for determining fracture toughness KIC of materials ranging from metallic alloys to brittle ceramics and their composites. A round-rod specimen having a V-grooved spiral line with a 45° pitch is subjected to pure torsion. This loading configuration creates a uniform tensile-stress crack-opening mode, Mode-I, with a transverse plane-strain state along the grooved line. This technique is analogous to the conventional test method using a compact-type specimen with a thickness equivalent to the full length of the spiral line. KIC values are determined from the fracture load and crack length with the aid of an in-house developed 3-D finite element program (TOR3D-KIC). A mixed mode (modes I and III) fracture toughness value can be determined by varying the pitch of the spiral line or varying the ratio of axial to torsion loads. Since the key information needed for determining KIC values is manifested within a small region near the crack tip, the specimen can be significantly miniaturized without the loss of generality. Limited results obtained for various materials are compared with published KIC values, showing differences of less than 2% in general and 6% maximum in one case. The experimental technique and theoretical basis of the proposed method are presented in detail.
The Plasma Spraying of Nitride Coatings
Authors: Rusowicz Artur
Published: January 2009

Ceramics without oxides (i.e. nitrides) are vulnerable to oxidation in the presence of plasmagenic gases or oxygen from atmosphere during plasma spraying. Initially there were two ways of oxidation’s avoidance: first, modification of powder material and second, limitation of an oxygen’s stream flowing into plasma. The modification of the powder material consisted in covering of ceramic granules with material limiting contact with oxygen or usage of easily oxidizing material getting oxygen away (i.e. a graphite thin layer over carbide’s granule). This method seemed to be less economic due to additional increase in powder’s price. Eventually the second conception of limiting of oxidation was considered as worth developing. Originally the process of spraying was carried out in vacuum (VPS – Vacuum Plasma Spraying). Then application of atmosphere under control was examined (CAPS – Controlled Atmosphere Plasma Spraying). It includes process of spraying with application of different gaseous controlled atmospheres under different pressure (decreased, normal and increased). There are three kinds of atmosphere: neutral (argon, nitrogen), reductive (carbon monoxide, methane) and acting with spraying material. Eventually the process was carried out under atmospheric pressure with gaseous ring-shaped protective gas jet. Moreover the experiments with spraying of nitrides were described (AlN, TiN, Si3N4). The most suitable characteristics of the process was chosen and some properties of coatings were examined as well.
The Developmental Trends in Heat Spraying of Ceramic Coating
Authors: Rucin´ski Adam , Rusowicz Artur
Published: January 2009

In the paper development of used ceramic materials and ways of their production with the aid of heat spraying is presented. According to a needness of continuous increase of coating’s mechanical resistance (high wearability, low brittlesness), corrosion resistance and profitable thermal and electric properties, current ceramic materials characterized by more and more attractive useful properties are described. Also a role of flame and plasma spraying including developmental trends towards prodution of coatings are underlined. The paper contains the own solution of plasma spraying of coatings consists in operation of the process under atmospheric pressure with gaseous ring-shaped protective jet. Additionally, proper choice of spraying’s parameters and some interesting characteristics of coatings are presented along with the examination of their structure (i. e. a rate of fusion, an oxidation of granules in a coating). Moreover the applications of coatings on machine parts (i. e. mechanical seal of impeller pumps, blades of turbines) are mentioned.
An Improved Approach to the Semi-Process-Oriented Implementation of Standardised ERP-Systems
Authors: Ku¨hl Lukas W. H. , Kno¨ll Heinz D.
Published: January 2009

The improved approach is considered as a life-cycle model that combines the necessities of process improvement projects and the implementation of modern integrated Standard Software systems. To improve the company’s business processes by means of the Standard Software implementation, each phase of the entire implementation life cycle puts its focus on optimising the customer’s underlying business processes. In addition, to intensify the benefits resulting from the process-oriented system implementation, the presented approach is extended by a certain guidance to organise a process-driven project team.
Investigation of Drillstring Transverse Vibrations at Rotary Drilling of Inclined Wells
Authors: Tikhonov Vadim S. , Safronov Alexander I. , Gelfgat Michael Ya.
Published: January 2009

Significant part of axial compression load transferred to the bit while drilling of wells with high zenith angles is resisted by service drill pipes. By the action of static critical load, buckling of drillstring occurs initially in the shape of a sinusoid and subsequently, as the load increases, in the shape of a helix. Drillstring rotation promotes the occurrence of critical modes. As a result the drillstring can start snaking motion at the low side of the hole. When the rotary speed grows, whirling of the drillstring can occur with axial load much lower than the buckling load. In this paper, a nonlinear mathematical model of lateral vibrations of a rotating drillstring in straitened space of a straight inclined hole is proposed. A numerical method to solve drillstring motion equations has been developed that allowed to reduce time of computation. This made it possible to conduct a detailed study of how the main drilling parameters (compression load, drillstring rotary speed, hole angle, friction factor, etc.) effect drillstring motion in the well. Results of the study may be used to choose drillstring operation modes for rotary drilling of inclined and horizontal wells.
The Use of Aniline Blue for the Determination of Dead Phytoplankton, Zooplankton and Meroplankton in LC50 Testings After 96 Hours: A Re-Evaluation of the US Environmental Protection Agency Methodology
Authors: Seepersad Balram , Ramnath Kelvin , Dyal Shyam , Mohammed Reeza
Published: January 2009

There is a need for a reliable staining technique to distinguish between live and dead organisms following LC50 tests. This is especially so in cases where organisms can be stressed or even become unconscious and appear dead to the aided or naked eyes. Visual observations under such conditions can result in an LC50 value shifting to the lower concentration thereby imposing stiffer guidelines for compliance. Aniline blue can only stain individuals which are physiologically dead imposing an accurate live-dead evaluation and producing a true LC50 value. Guidelines imposed using such data will facilitate compliance and provide an accurate value for an LC50.
Geochemical and Mineralogical Assessment of Lime Stabilized Waste From Petroleum Industry in Croatia
Authors: Durn Goran , Gaurina-Međimurec Nediljka , Meandzˇija Ivan , Veronek Boris , Mesic´ Sanja
Published: January 2009

The aim of this study was geochemical and mineralogical assessment of materials from two already closed pits. Total testing and leachate testing (Equilibrium Leach Test and Sequential Leach Test) of topsoil, waste stabilized with lime and underlying rock was performed on composite samples. Analysis of underground water from underlying rock was also accomplished. Major pollutants in stabilized waste from investigated locations differ. High total values of some heavy metals in stabilized waste from one of the investigated locations can probably be attributed to high barite content (mercury, zinc and cadmium) and pipe dope (lead). Mercury, zinc and cadmium are enriched in the organic-sulfide fraction that might indicate they are tied up as sulfide impurities in barite. In distilled water lecheate of stabilized waste from this location higher concentrations of Pb, Hg and TOC were observed. In the stabilized waste from the second location high total values of TPH, PAH and BTEX were detected, while distilled water lecheate is enriched in Hg, AOX, TOC and TPH. This investigation shows that stabilization with lime is not always suitable method for treatment of wastes from petroleum industry, particularly those that are contaminated with both organic and inorganic contaminants. Proper characterization of the waste material to be processed is needed in order to select the most appropriate method of treatment. Our ongoing research study uses different pretreatment techniques and different absorbents (organophilic clay, zeolite, calcined siliceous earth, etc.) to preferentially absorb organic contaminants that can be used before stabilization/solidification.
How Crosco — A Drilling, Workover and Well Service Contractor — Meets the Requirements of Environmental Protection
Authors: Flerin-Biber Huberta
Published: January 2009

How to fulfill requirements of environmental protection set by operator so that their fulfillment does not overburden the financial part of the Contract or violate the local legislation? Are these requirements always the same, or they differ depending on the operator, or the part of the world and country where operations are being executed? In Crosco, we believe that we have the answers to those questions. The fact that we have succeeded to survive in the competitive world market and that Crosco’s share in that market is constantly growing speaks in favor of that. Since December 17th 1996, when the part of INA-Naftaplin dealing with exploration and exploitation drilling including well services was separated from Naftaplin as an independent drilling contractor under a new name, Crosco Co. Ltd. was forced to turn to the world market overnight. Up to that moment Crosco was fairly safe and comfortable as a part of INA, the state-owned oil company. But from that moment on, Crosco had to face the challenge of the foreign market and particularly, the operators’ requirements for the environmental protection. The requirements varied a lot and so did the environmental policies implemented by operators. To qualify for tendering, not to speak of successfully winning a contract, Crosco and its employees were forced to step suddenly into a completely new area — the Environmental Protection. Crosco has succeeded in overcoming that obstacle and finding its own way of how to satisfy operator’s environmental requirements and local legislation optimally. Crosco’s method has shown to be efficient, simple and inexpensive. The paper will expound and analyze the following: • Operators’ requirements and their environmental policies. • Local legislation, environmental discharge limits and available methods of waste treatment. • Ways how Crosco as contractor fulfills the set environmental requirements.
The Application of Bonding Mechanisms for Environmental Compliance and Its Economic Impacts on Oil Projects
Authors: Ferreira Doneivan F. , Suslick Saul B.
Published: January 2009

The present paper describes the financial assurance system (bonding system), an incentive approach being adopted by several countries to guarantee or fund environmental obligations and ensure environmental performance. Environmental compliance involves meeting all end-of-leasing obligations, including closure and decommissioning operations. This paper also identifies the main forms of potential environmental damages resulting from upstream activities and their potential financial impact on the regulatory agency. It will be demonstrated how bonding instruments may help reduce such risks by: (1) providing financial incentive for environmental compliance; (2) safeguarding government and taxpayers by attaining reasonable protection from default at a minimum increase in project costs; and (3) protecting the environment from potential harm resulting from failure to carryout proper closure operations in a timely fashion. A model is proposed for a hypothetical scenario and an analysis is performed in order to identify potential financial impacts on oil projects.
Health, Safety and Environmental Management Systems Auditing for an Integrated Oil and Gas Company in Trinidad and Tobago
Authors: Maharaj Priya S. , Dyal Shyam , Ramnath Kelvin
Published: January 2009

The Petroleum Company of Trinidad and Tobago Limited (Petrotrin) has developed and implemented a Health, Safety and Environmental (HSE) Management Audit System of its Exploration and Production, and Refining and Marketing Strategic Business Units. The main objective of this internal company audit was to determine the missing ‘gaps’ or elements from the current HSE Management System and to recommend alternate HSE Management System elements to create a more efficient Management System. The audit checklists and results effectively listed the observations, problems, and compliance issues, as well as corrective actions for improvement in accordance with the ISO 14001 and HSE Guidelines of the Exploration and Production Forum and 29CFR 1910.119 - Process Safety Management of Highly Hazardous Chemicals, Standards as well as the Company HSE key strategic directions including: • 100% compliance with local Environmental and Safety Regulations; • Targets of zero accidents and oil spills; and • Certification HSE Management Systems, for all Company operations. Senior personnel or drivers of the management systems within the Company were interviewed using this structured approach. The results from this company wide internal audit revealed that generally the overall HSE Management Strategies have been developed, but are not fully implemented, although they are formalized in the Environmental and Occupational Health and Safety Policies of the Company. HSE is undoubtedly regarded as a priority issue within Petrotrin’s operations, however there is the need to improve the documentation of formalized HSE Management System Procedures, thereby improving the enforcement and maintenance of the management system.