bluuebunny/crossref_metadata_2025 huggingface dataset:
Read‐across to rank skin sensitization potential: subcategories for the Michael acceptor domain
Authors: Schultz Terry Wayne , Rogers Kathryn , Aptula Aynur Osman
Published: January 2009

Background:  Eliminating animal testing for skin sensitization is a significant challenge in consumer safety risk assessment. To be able to perform resilient risk assessments in the future, one will need alternative approaches to fill the data gaps.

Objectives:  To this end, we propose a subcategory‐based read‐across approach to estimate and rank skin sensitization potential of chemicals. The example described here is for the mechanism of Michael‐type nucleophilic addition with subcategories being limited to carbonyl‐containing compounds.

Patients/Methods:  In this approach, in silico tools based on structural alerts were used to determine both the mechanism of protein binding and the relative subcategories within that mechanism.

Results:  Fifty compounds previously evaluated in the in vivo mouse local lymph node assay (LLNA) were placed in 10 subcategories defined by their polarized α,β‐unsaturated substructure. To offset the limitations and skewness of the published in vivo data, in chemico glutathione (GSH) depletion data also were included.

Conclusions:  It was shown that the read‐across approach can be successfully used to rank qualitatively skin sensitization potential of an untested carbonyl‐containing Michael acceptor chemical by using subcategories. Moreover, the use of the more resilient in chemico GSH depletion data added further support to the read‐across result.
There is an association between contact allergy to aluminium and persistent subcutaneous nodules in children undergoing hyposensitization therapy
Authors: Netterlid Eva , Hindsén Monica , Björk Jonas , Ekqvist Susanne , Güner Nuray , Henricson Kent Åke , Bruze Magnus
Published: January 2009

Background:  The development of persistent itchy nodules at the injection site following hyposensitization therapy with aluminium‐precipitated antigen extract has been described in several reports. Occasionally, contact allergy to aluminium has been reported in individuals with such nodules.

Objectives:  To investigate if hyposensitization therapy can induce contact allergy to aluminium and examine if there is any association between persistent subcutaneous nodules and aluminium allergy.

Patients/methods:  Sixty‐one children with allergic asthma and/or allergic rhinitis participated in the study of whom 37 had had hyposensitization therapy. The study consisted of a non‐clinical part based on a questionnaire and a clinical part with a physical examination, self‐assessment of itching, and patch testing. To secure an unbiased evaluation of possible reactions, the investigators were blinded.

Results:  Contact allergy to aluminium was found in eight participants, all in the exposed group (8/37 versus 0/24, P = 0.02). Examination showed nodules on the upper arms in 13 participants, all in the group exposed to hyposensitization therapy. Nodules were over‐represented in patients with contact allergy to aluminium.

Conclusions:  There was a statistically significant association between contact allergy to aluminium and persistent subcutaneous nodules in children who had had hyposensitization therapy.
Influence of Isoflurane General Anesthesia or Anesthesia and Surgery on Thyroid Function Tests in Dogs
Authors: Wood M.A. , Panciera D.L. , Berry S.H. , Monroe W.E. , Refsal K.R.
Published: January 2009

Background:Anesthesia and surgery affect thyroid function tests in humans but have not been studied in dogs.

Hypothesis:Anesthesia and anesthesia with surgery will affect thyroid function tests in dogs.

Animals:Fifteen euthyroid dogs.

Methods:Prospective, controlled, interventional study. Dogs were assigned to one of 3 groups: control, general anesthesia, and general anesthesia plus abdominal exploratory surgery. Dogs in the anesthesia and surgery groups were premedicated with acepromazine and morphine, induced with propofol, and maintained on isoflurane. Samples for measurement of serum thyroxine (T4), free T4(fT4) by equilibrium dialysis, triiodothyronine (T3), reverse T3(rT3), and thyroid‐stimulating hormone concentrations were collected from each dog immediately before premedication, at multiple times during anesthesia, surgery, 4, 8, 12, 24, 36, and 48 hours after anesthesia, once daily for an additional 5 days, and once 14 days after anesthesia. Sampling was performed at identical times in the control group.

Results:Serum T4decreased significantly from baseline in the surgery and anesthesia groups compared with the control group at 0.33 (P= 0.043) and 1 hour (P= 0.018), and 2 (P= 0.031) and 4 hours (P= 0.037), respectively, then increased significantly in the surgery group compared with the control group at 24 hours (P= 0.005). Serum T3decreased significantly from baseline in the anesthesia group compared with the control group at 1 hour (P= 0.034). Serum rT3increased significantly from baseline in the surgery group compared with the control and anesthesia groups at 8 (P= 0.026) and 24 hours (P= 0.0001) and anesthesia group at 8, 12, 24, and 36 hours (P= 0.004,P= 0.016,P= 0.004, andP= 0.014, respectively). Serum fT4increased significantly from baseline in the surgery group compared to the control at 24 hours (P= 0.006) and at day 7 (P= 0.037) and anesthesia group at 48 hours (P= 0.023).

Conclusions and Clinical Importance:Surgery and anesthesia have a significant effect on thyroid function tests in dogs.
An Investigation of the Action of Neutral Protamine Hagedorn Human Analogue Insulin in Dogs with Naturally Occurring Diabetes Mellitus
Authors: Palm C.A. , Boston R.C. , Refsal K.R. , Hess R.S.
Published: January 2009

Background: Neutral Protamine Hagedorn human analogue insulin (Humulin N) is commonly used for treatment of canine diabetes mellitus (DM). However, blood glucose and serum insulin concentrations in Humulin N‐treated dogs with naturally occurring DM have not been reported.

Objective: To investigate blood glucose and serum insulin concentrations in the clinical setting of client‐owned Humulin N‐treated dogs with naturally occurring, well‐regulated DM.

Animals: Ten client‐owned dogs with naturally occurring, well‐regulated DM.

Methods: In this clinical study, blood glucose and serum insulin concentrations were measured when dogs received food and insulin (T0), at approximately every half hour for the next 2 hours, and then approximately every 2 hours for an additional 8 hours. Insulin duration of action was defined as the number of hours from T0 to the lowest blood glucose concentration and until blood glucose concentration returned to an interpolated value of 70% of basal blood glucose concentration (Glucoseb).

Results: Mean percent of insulin‐induced blood glucose suppression was 49.9 ± 17.1% (median, 46%; range, 29–78%). Insulin duration of action ranged from 4 to 10 hours. Blood glucose concentration increased initially and returned to Glucoseb within 0.6–2.2 hours after T0 in 5 dogs. This initial blood glucose surge then was followed by blood glucose suppression in all 5 dogs.

Conclusions and Clinical Importance: These results suggest that Humulin N administered SC twice daily is an effective mode of treatment for dogs with naturally occurring DM. Postprandial hyperglycemia is present in some well‐regulated diabetic dogs treated with Humulin N.
Differential stimulation of myofibrillar and sarcoplasmic protein synthesis with protein ingestion at rest and after resistance exercise
Authors: Moore Daniel R. , Tang Jason E. , Burd Nicholas A. , Rerecich Tracy , Tarnopolsky Mark A. , Phillips Stuart M.
Published: January 2009

We aimed to determine whether there is a differential stimulation of the contractile myofibrillar and the cellular sarcoplasmic proteins after ingestion of protein and how this is affected by resistance exercise. Fasted (FAST) muscle protein synthesis was measured in seven healthy young men with a primed constant infusion of l‐[ring‐13C6]phenylalanine. Participants then performed an intense bout of unilateral resistance exercise followed by the consumption of 25 g of whey protein to maximally stimulate protein synthesis. In the rested (FED) leg myofibrillar (MYO) protein synthesis was elevated (P < 0.01) above FAST at 3 h (∼163%) but not at 1 and 5 h (P > 0.05). In contrast, MYO protein synthesis in the exercised (FED‐EX) leg was stimulated above FAST at 1, 3 and 5 h (∼100, 216, and 229%, respectively; P < 0.01) with the increase at 5 h being greater than FED (P < 0.01). Thus, the synthesis of muscle contractile proteins is stimulated by both feeding and resistance exercise early (1 h) but has a greater duration and amplitude after resistance exercise. Sarcoplasmic (SARC) protein synthesis was similarly elevated (P < 0.01) above FAST by ∼104% at 3 h in both FED and FED‐EX suggesting SARC protein synthesis is stimulated by feeding but that this response is not augmented by resistance exercise. In conclusion, myofibrillar and sarcoplasmic protein synthesis are similarly, but transiently, stimulated with protein feeding. In contrast, resistance exercise rapidly stimulates and sustains the synthesis of only the myofibrillar protein fraction after protein ingestion. These data highlight the importance of measuring the synthetic response of specific muscle protein fractions when examining the effects of exercise and nutrition.
Passive membrane properties and electrotonic signal processing in retinal rod bipolar cells
Authors: Oltedal Leif , Veruki Margaret Lin , Hartveit Espen
Published: January 2009

Rod bipolar cells transmit visual signals from their dendrites, where they receive input from rod photoreceptors, to their axon terminals, where they synapse onto amacrine cells. Little is known, however, about the transmission and possible transformation of these signals. We have combined axon terminal recording in retinal slices, quantitative, light‐microscopic morphological reconstruction and computer modelling to obtain detailed compartmental models of rat rod bipolar cells. Passive cable properties were estimated by directly fitting the current responses of the models evoked by voltage pulses to the physiologically recorded responses. At a holding potential of −60 mV, the average best‐fit parameters were 1.1 μF cm−2 for specific membrane capacitance (Cm), 130 Ω cm for cytoplasmic resistivity (Ri), and 24 kΩ cm2 for specific membrane resistance (Rm). The passive integration of excitatory and inhibitory synaptic inputs was examined by computer modelling with physiologically realistic synaptic conductance waveforms. For both transient and steady‐state synaptic inhibition, the inhibitory effect was relatively insensitive to the location of the inhibition. For transient synaptic inhibition, the time window of effective inhibition depended critically on the relative timing of inhibition and excitation. The passive signal transmission between soma and axon terminal was examined by the electrotonic transform and quantified as the frequency‐dependent voltage attenuation of sinusoidal voltage waveforms. For the range of parameters explored (axon diameter and length, Ri), the lowest cutoff frequency observed was ∼300 Hz, suggesting that realistic scotopic visual signals will be faithfully transmitted from soma to axon terminal, with minimal passive attenuation along the axon.
Condensation Heat Transfer of Carbon Dioxide Inside Horizontal Smooth and Microfin Tubes at Low Temperatures
Authors: Kim Yoon Jo , Jang Jeremy , Hrnjak Predrag S. , Kim Min Soo
Published: January 2009

This paper presents heat transfer data for the condensation of CO2 at low temperatures in horizontal smooth and microfin tubes. The test tubes included a 3.48 mm inner diameter smooth tube and a 3.51 mm melt-down diameter microfin tube. The test was performed over a mass flux range of 200–800 kg/m2 s and at saturation temperatures of −25°C and −15°C, respectively. The effect of various parameters—diameter, mass flux, vapor quality, and temperature difference between inner wall and refrigerant—on heat transfer coefficient and enhancement factor is analyzed. The data are compared with several correlations. The existing correlations for the smooth tube mostly overpredicted the heat transfer coefficients of the present study, which is possibly resulted from the characteristics of carbon dioxide as a “high pressure refrigerant.” For the microfin tubes, due to the complexity and variety of fin geometry and flow mechanisms in microfin tubes, most of the correlations for the microfin tube were not applicable for the experimental data of the present study. The average enhancement factors and penalty factors evidenced that it was not always true that the internally finned geometry guaranteed the superior in-tube condensation performance of the microfin tube in refrigeration and air-conditioning systems.
Mixed Convection Along a Semi-Infinite Vertical Flat Plate With Uniform Surface Heat Flux
Authors: Moulic S. Ghosh , Yao L. S.
Published: January 2009

Mixed-convection boundary-layer flow over a heated semi-infinite vertical flat plate with uniform surface heat flux, placed in a uniform isothermal upward freestream, has been investigated. Near the leading edge, the effect of natural convection can be treated as a small perturbation term. The effects of natural convection are accumulative and increase downstream. In the second region, downstream of the leading-edge region, natural convection eventually becomes as important as forced convection. The boundary-layer equations have been solved by an adaptive finite-difference marching technique. The numerical solution indicates that the series solution of the leading-edge region is included in that of the second region. This property is shared by many developing flows. However, the series solutions of local similarity or local nonsimilarity are only valid for very small distances from the leading edge. Numerical results for the local skin-friction factor, wall temperature, and local Nusselt number are presented for Pr=1 for a wide range of Grx*∕Rex5∕2, where Grx* is a local modified Grashof number and Rex is a local Reynolds number. The results indicate that cfxRex1∕2 and NuxRex–1∕2 increase monotonically with distance from the leading edge, where cfx is the local skin-friction factor and Nux is the local Nusselt number, and approach the free-convection limit at large values of Grx*∕Rex5∕2, although the velocity distribution differs from the velocity distribution in a free-convection boundary layer.
Co-Combustion of Municipal Sludge With Wood/Coal in CFB: Enrichment of Phosphorous and Cadmium in Ashes
Authors: A˚mand Lars-Erik , Leckner Bo , Hansson Leif , Norrlo¨w Olof
Published: January 2009

Municipal sludge, originating from two wastewater treatment plants in Sweden, has been burned together with wood pellets or bituminous coal in a circulating fluidised bed (CFB) boiler equipped with a secondary cyclone and bag filter for fly ash removal. Such co-combustion is an alternative to mono-combustion of sludge. The sludge is burned in either mechanically dewatered or pre-dried form. The mechanically dewatered sludge was fed with a pump, but pre-dried sludge could be fed by the fuel feed system normally used for coal. Both types of sludge were burned with either wood-pellets or coal as main fuel under identical operating conditions, typical for a CFB boiler. The focus was on ash balances and on analysis of fuels and ashes to obtain concentrations of relevant species. The presence of phosphorous (P) is of special interest in relation to trace elements, such as mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), nickel (Ni) and zinc (Zn). For this reason a comparison has been made between these trace elements and phosphorous in the various ashes and the original sludge as well as other sources of phosphorous that could be used for agricultural purposes. The results show that sewage sludge and fly ash, after combustion of sludge, contain similar amounts of phosphorous as other phosphorous sources for agricultural use, but the levels of trace elements in relation to phosphorous (Hg, Cd, Pb, Cr, Cu) are higher than in animal manure and artificial fertilizer and higher than the present limits in Sweden.
Fabrication of Miniature Silicon Wafer Fuel Cells Using Micro Fabrication Technologies
Authors: Yu Jingrong , Cheng Ping , Ma Zhiqi , Yi Baolian
Published: January 2009

The fabrication of miniature silicon wafer fuel cells by micro-fabrication technologies and their performance evaluation are presented in this paper. Various thickness of Nafion membranes, such as Nafion 117, 115, and 112, were tested as electrolytes in a miniature single cell operating with dry H2/O2. Among these membranes, Nafion 112 (with the thinnest thickness) gave the best performance of 92.2 mW/cm2 at 250mA/cm2. In order to enhance the output voltage of the fuel cell, a miniature twin-fuel-cell was fabricated in series using two membrane-electrode-assemblies of Nafion 112 membrane sandwiched between two silicon substrates. The novel structure of the miniature twin-fuel-cell is that the electricity interconnect from the cathode of one cell to the anode of another cell is made on the same plane. The interconnect is fabricated by sputtering a layer of gold on the top of the silicon wafer. Silicon dioxide is deposited on the silicon wafer adjacent to the gold layer to prevent short-circuiting between the twin-cells. At ambient conditions, the measured peak power densities of the miniature twin-fuel-cell operating with H2/O2 and 1.5M methanol/O2, are 190.4mW/cm2 and 15.4mW/cm2, respectively.
Assessing the Impact of Inverter Current-Ripple on SOFC Performance
Authors: Gemmen Randall S. , Famouri Parviz , Johnson Christopher
Published: January 2009

The effect of inverter ripple current on fuel cell stack performance is not well understood. This paper provides a first-order examination of the impact of inverter load dynamics on SOFC fuel cell operation. Previous work using steady-state fuel cell loading has shown that DC-current loading itself results in degradation of the fuel cell, albeit in ways yet to be fully understood. This result suggests that the varying reactant conditions that result from ripple may modify degradation processes, and, therefore, the lifetime of the cells. This paper investigates these conditions through the use of a dynamic one-dimensional model for the detailed mass transport occurring within the electrode of a cell. In this work, the inverter load is imposed as a boundary condition to the transient model. Results show the behavior of the reactant concentrations within the stack electrodes under inverter loads with frequencies between 60 Hz and 1250 Hz. It is concluded that a ripple factor of less than 6% be used to ensure minor impact to the conditions at the electrode-electrolyte interface.
Improved Multi-Functionality of Ni/YSZ Cermet Anode by Optimizing Fabrication Processes
Authors: Song H. , Lee J.-H. , Kim J. , Kim S.-W. , Lee H.-W.
Published: January 2009

Ni/YSZ cermet anode is required to simultaneously satisfy various properties as a key component of anode-supported type SOFC, since the cell performance is highly dependent upon anode properties. Ni/YSZ anode, with complicated structural features, consists of three different phases such as metallic Ni, YSZ ceramic and pores. Furthermore, the correlation between those structural features makes it difficult to independently optimize individual function of anode such as gas permeability, electrical conductivity and electrochemical activity. Thus, a great deal of efforts to establish structure-property-processing correlation has been made in this study in order to achieve improved anode performance. Critical process steps in anode fabrication were investigated in terms of raw material selection, mixing and granulation, and forming, judging from the performance evaluation of anode substrate. An optimized fabrication process, enabling to produce thin and large-area anode substrate with improved uniformity, will be presented with respect to multifunctional performance of Ni/YSZ anode, and resulting cell performance will be also discussed.
The Potential Generating Capacity of PV-Clad Residential and Commercial Buildings in Nigeria
Authors: Fagbenle R. ‘Layi , Oladiran M. T. , Oyedemi T. I.
Published: January 2009

Nigeria’s grid electricity supply of 5.881 GW installed capacity in the period 1994–1997 has experienced a sharp decline over the past five years to about 3 GW by 2002, even as electricity demand has grown due to population pressures, industrialization, and urban migration. Indeed the present situation is a near total collapse of the state power utility services, as total prolonged blackouts have been commonplace throughout the country in the past couple of years, and the situation may grow much worse unless significant shift in energy policy and investment takes place urgently. Diversification of energy sources to reduce the overt increasing dependence on fossil fuel generation and a shift towards renewable energy generation, particularly solar photovoltaic electricity, is a highly desirable policy shift. Among the gains would be reduced carbon emission into the environment and reduced transmission and distribution losses due to the possibility of decentralized generation and localized use of solar photovoltaic electricity. This paper examines the use of decentralized and gridconnected solar PV in building cladding as a pragmatic solution to the current power problems of Nigeria. The results of an ongoing investigation of the potential generating capacity of stand-alone and grid-connected solar PV cladding on residential and commercial buildings in Nigeria. An economic analysis of the proposed system is also considered as well as suggestions on financing. The cost of electricity from the proposed solar PV-clad buildings, calculated using an assumed 8% discount rate and a 25-year life expectancy was found to be significantly higher, in the double digits, than the present national tariff. Thus, novel financing schemes required are examined in the paper.
Integration of the Advanced Dish Development System
Authors: Diver Richard B. , Andraka Charles E.
Published: January 2009

The Advanced Dish Development System (ADDS) project is an advanced, system-level dish/Stirling solar power system development activity aimed at the remote power marketplace. Unlike any of the other U.S. Department of Energy (DOE) Concentrating Solar Power (CSP) program sponsored activities, the ADDS project is being integrated by Sandia National Laboratories (SNL). Although SNL and the National Renewable Energy Laboratory (NREL) help the DOE manage the CSP program, previous system development activities were all integrated by industry partners, with SNL and NREL providing technical support. The ADDS project is a technology development activity with the specific objective of fielding a remote, off-grid, water-pumping dish/Stirling system on an Indian reservation in the Southwestern U.S. To meet this objective, the WGAssociates (WGA) solar concentrator and controls, and the SOLO 161 Stirling Power Conversion Unit (PCU) were selected for the major components. The WGA concentrator and controls technology are well advanced and utilize structural facet mirror technology and concentrator structure and controls technology developed over decades with DOE and private investment. The SOLO 161 Stirling PCU, including solar receiver and controls, has also benefited from decades of development. Two ADDS designs have been developed. A first-generation (Mod 1) grid-connected prototype system was fielded at the National Solar Thermal Test Facility (NSTTF) in Albuquerque, NM in the summer of 1999, primarily for the purpose of reliability improvement. In 2000, an upgraded, second-generation (Mod 2) system, including a standalone water-pumping ADDS was developed, and in 2001 it was installed and demonstrated at the NSTTF. While the value of remote power electricity is greater than for utility power, (estimates range from 20 to more than 50 cents per kilowatt-hour) the remote environment presents additional requirements. The ADDS project has been a first step in the development and demonstration of a dish/Stirling system that can potentially address this large commercial opportunity. Integration of the ADDS has also been challenging and rewarding. As a result of the ADDS project, insights beyond specific component expertise have been obtained. Even though we have not been able to achieve our original objective of fielding a dish/Stirling system on an Indian reservation because of reduce budgets, the ADDS project has been successful in that most of the original system specifications and technical objectives were met or exceeded. It has also served as a valuable test bed for the evaluation of advanced technology in a system context. The ADDS technology and results are presented in other papers. In this paper, the integration philosophy and approaches utilized in the various stages of the ADDS project are presented and described. Insights gained from integration of the ADDS are also discussed.
Implementing Disaster Plans for Municipal Solid Waste Systems
Authors: Martin Janet H.
Published: January 2009

Municipal solid waste managers face an urgent need to review disaster plans as well as the myriad of other management plans for health, safety and welfare of employees and the service area. Other planning areas include financial and capital improvements. The planning process is an important management tool. The evaluation of management is one of the factors included in the assignment of municipal credit ratings. This paper profiles how Fitch Ratings incorporates management in their credit analysis and provides key points for solid waste managers to consider as they prepare or refresh plans.
How Implementation of Retrofits Required by the Clean Air Act Amendments of 1990 Affects Waste-to-Energy Facility Operations, Plant Efficiency and Finances
Authors: Shabat Dan
Published: January 2009

This paper considers the direct and indirect impacts on facility operations and financial performance resulting from the retrofits required to comply with the tighter emissions standards and more stringent operating requirements imposed by the Clean Air Act Amendments of 1990 (CAAA). While all large municipal waste combustors (>250 tons per day) and many smaller units (>250 TPD) have already made the initial financial and operational adjustments required by CAAA-induced changes, many small combustors preparing to comply with the Subpart BBBB requirements, have yet to experience these changes. Since most large WTE facilities only began operating under the new CAAA scenario during or shortly before December 2000, the long-term cost impacts of these changes are only now becoming clear. The Subpart BBBB standards are nearly identical to the standards imposed on large combustors. Each existing WTE facility operator affected by Subpart BBBB must determine whether the standards can be met with existing air pollution control devices and existing emission monitoring equipment, or if a facility retrofit is required. If a facility retrofit is required, the economics of continued operation as compared to alternative disposal options must be considered.
Energy Recovery From Municipal Solid Wastes by Gasification
Authors: Klein Alexander , Themelis Nickolas J.
Published: January 2009

Recovery of energy from MSW by combustion in Waste-to-Energy (WTE) plants reduces landfilling and air/water emissions, and also lessens dependence on fossil fuels for power generation. The objective of this study was to assess the potential of gasification processes as an alternative to the combustion of MSW. Gasification uses a relatively small amount of oxygen or water vapor to convert the organic compounds into a combustible gas. Its advantages are a much lower volume of process gas per unit of MSW and thus smaller volume of gas control equipment; also, gasification generates a fuel gas that can be integrated with combined cycle turbines or reciprocating engines, thus converting fuel energy to electricity more efficiently than the steam boilers used in combustion of MSW. The disadvantages are the need to pre-process the MSW to a Refuse Derived Fuel (RDF) and the formation of tars that may foul the downstream gas cleaning and energy conversion systems. This paper presents two prominent gasification processes and compares their energy characteristics with a mass burn WTE and a suspension firing WTE that uses shredded WTE. The results showed potential energy and capital cost advantages for gasification. However, long-term operating results from industrial plants are needed for gasification to become a practical alternative to combustion.
High Pressure Zones at Different Scales During Ice-Structure Indentation
Authors: Li Chuanke , Barrette Paul , Jordaan Ian
Published: January 2009

In order to improve the estimation of the ice load during ice-structure interaction, this study aims to investigate the behaviour of high pressure zones at different scales. Small scale indentation tests of ice with four different sizes of indentors (10 mm, 20 mm, 40 mm and 100 mm in diameter) were conducted at Ocean Engineering Research Centre of Memorial University. The tests were conducted at −10 °C. The grain sizes were scaled up with the indentor sizes. The tests consist of three series with different orders of displacement rates. In this paper, Part of the field test data will be retrieved for the investigation. Microstructural changes of the ice after deformation in laboratory will be studied. A relationship between stress and nominal contact area is derived based on the data. Numerical simulations are conducted for the series with low displacement rates of laboratory tests. The simulation shows a good agreement with the tests.
Effect of the Yield to Tensile Ratio, Y/T, on Structural Reliability of Linepipes Subject to Bend Loading
Authors: Ernst Hugo A. , Bravo Richard E. , Villasante Jose´ A. , Izquierdo Alfonso
Published: January 2009

A model based on elastic-plastic fracture mechanics (EPFM) and plasticity theory, was developed to study the effect of the Yield (Y) to Tensile (T) ratio, Y/T, on the structural reliability of linepipes with part through the thickness (PTT) circumferential defects subject to bend loading. The analysis allows for load or deformation control situations. The results are shown in terms of curves of critical defect size vs. the controlling variable, i.e. load or deformation. For each one of the materials studied, different cases with different Y/T values were considered. Even for the lower limits of experimental data, i.e. larger Y/T, the materials have adequate defect tolerance. A Leak Before Break Analysis was also conducted.
Route to Chaos of an Articulated Offshore Loading Platform
Authors: Shashikala A. P.
Published: January 2009

Articulated Loading Platforms are compliant structures which undergo excessive displacements due to large hydrodynamic loads produced by wind, waves and currents. Prediction of nonlinear behavior of these complex structures in the nonlinear environment is extremely difficult. The discontinuity in the mooring line stiffness at the equilibrium position due to slackening of the mooring line between tower and tanker introduces nonlinearity in the equation of motion. An attempt to study the effect of the highly nonlinear restoring force and hydrodynamic forces on the system was performed. The time domain response analysis was done on the basis of approximate analytical investigations. The solution of the nonlinear simultaneous equations was performed and the results were interpreted by means of phase plots and poincare mapping. The effect of forcing amplitude on the behavior of the system was studied by varying the frequency ratio. Possible occurrence of sub harmonic and chaotic responses and hence different routes to chaos were also identified. These results can be made use of in the design of mooring lines to avoid structural instabilities in the evolving offshore environment.
Investigation of Unexpected Sea-States
Authors: Toffoli Alessandro , Lefe`vre Jean Michel , Josse Patrick , Monbaliu Jaak
Published: January 2009

It is assumed that dangerous and unexpected sea-states may occur if the sea conditions are fairly rough. It is therefore of concern to meteo centers to include sea-state related parameters in marine weather forecast when they exceed a certain threshold. To select appropriate parameters that can point at dangerous wave events, the sea-state at the time and location of shipping accidents reported as being due to bad weather by the Lloyd’s Marine Information Service (LMIS) were extracted from the ECMWF ERA-40 archive. The analysis of these wave parameters reveals the occurrence of apparently rather low sea-states (e.g. Hm0 < 4 m). To test the findings against the related oceanographic features, wave climatology was computed. The present study aims at finding a possible correlation between wave climate and shipping incidents to identify warning criteria.
A-Plasma: Use of Penetration Flux and the Plasma Process When Pipe Welding Type 316L of Thicker Dimensions
Authors: Larsson Christer , Stemne Daniel
Published: January 2009

The maximum penetration depth in inert shielded gas processes as TIG (≤ 3 mm) and keyhole plasma (≤ 8 mm) limit a highly weldable corrosion resistant alloy as the standard austenitic stainless steel 316L to be welded autogenously in dimensions above these maximum penetration depths. Thus an expansion of these penetration ranges would expand the selection of autogenously welded pipes classified by ASTM A312. Also an increase of the productivity rates in pipe welding of thicker dimensions due to less extensively preparations and welding procedures would be a benefit. Using an activated flux to achieve deeper penetration in the TIG process (A-TIG) is today a well-known and established method. In keyhole A-plasma is, however, limited research performed and the use of an activated flux in connection with the partial penetration plasma process is still not evaluated. In the present paper a discussion of different proposed mechanisms affecting the penetration characteristics is made. The experimental procedures when using flux constituents of oxides as SiO2 and TiO2 in connection with the keyhole plasma process and the partial penetration plasma process are also described. A maximum depth in partial penetration A-plasma of 15 mm has been achieved. This is an improvement of 4 times compared with the ordinary partial penetration plasma process. The depth to width ratio became in this case 1.00, which increased the ratio about 7 times. The longitudinal seem welding using two-sided partial penetration A-plasma is limited by the demands of a good groove fitting but a new process for girth welding in thicker dimensions (t ≤ 25 mm) of type 316L is achieved. The keyhole A-plasma process is not recommendable due to the narrow parameter box that changes the non-penetration mode to a cutting mode too abruptly.
Breaking Length of Sheet Ice Against Sloping Structure
Authors: Feng W. , Shi Z. M. , Liu L. M. , Li F.
Published: January 2009

The interaction between sheet ice and sloping structure was studied. Models were built up according to the emersed part and floating part of the ice sheet respectively. Bending moment distribution in ice sheet was analyzed to determine where bending failure would occur. The analytic solution of breaking length for sheet ice was got. And some new conclusions were also deduced, which could provide reference for design and field experiment of offshore ice-resistant structure. The results in this paper are consistent with the experimental data from previous researchers. The theoretical results of this paper can directly be used in the analysis of wide inclined structures.
Simulation of Submerged Slack Tethers and Their Interaction With the Environment
Authors: Carretero J. A. , Buckham B. J.
Published: January 2009

Tethered systems, underwater or otherwise, are nowadays used for very diverse tasks. Due to the complexity of such systems, it is necessary to simulate them for design, operation and training purposes. This paper deals with an approach to simulation of tethered systems, in particular underwater remotely operated vehicles (ROVs), by incorporating contact forces acting between the tether and the environment into the dynamic model of the tether. This will ensure model fidelity when the tethered system is operated in a dense environment. In this paper, methods used to compute contact forces are described. In the calculation of contact dynamics, the distance between the tethered system and the environment is of utmost interest. Algorithms to determine the separation distance between the tether and the environment are discussed in the scope of this work. These algorithms are then incorporated into an existing dynamics model of the ROV tether. Finally, this paper concludes with a simple numerical example where a tether is moved in a concave environment. The distance between the tether and the environment is computed as the tether’s location and three-dimensional profile change with time.
The Master S-N Curve Approach to Fatigue Evaluation of Offshore and Marine Structures
Authors: Dong P. , Hong J. K.
Published: January 2009

As reported in the last OMAE conference (Dong, 2003), a robust structural stress method has been developed and validated for fatigue evaluation of ship structures through a major joint industry project. The structural stress method not only provides a consistent method for characterizing stress concentration effects on fatigue in different joint types and loading modes, but also offers a rapid estimation procedure for stress intensity factors for arbitrary joint geometries and loading modes in fracture mechanics context. As a result, a master S-N curve approach has been recently developed by using the mesh-insensitive structural stress parameter and its direct linkage to fracture mechanics principles. The master S-N curve is described by an equivalent structural stress range parameter which provides a single parameter description of stress concentration effects, thickness effects, and loading mode effects on fatigue in welded joints. A massive amount of S-N data since 1947, encompassing drastically different joint types, plate thickness, and loading modes have been used to validate the effectiveness of the master S-N curve approach. With the master S-N curve method, plate joints in ship structures, tubular joints in offshore structures, as well as pipe joints for riser applications can be collapsed into a singe curve, referred to as the master S-N curve. This paper provides the detailed theoretical development, application examples, and validation results. The applications for the master S-N curve approach will be illustrated by using various offshore/marine examples.
Uncertainty Modelling and Fatigue Reliability Calculation of Offshore Structures With Deteriorated Members
Authors: Karadeniz H.
Published: January 2009

This paper presents formulations and procedure of an efficient calculation of stress spectra and fatigue damage of offshore structures with deteriorated members in the uncertainty space. Calculation modeling of member deteriorations is represented by equivalent spring systems, which can be determined on basis of damage detection and stiffness degradation, with a deterioration uncertainty parameter. Redistributions of the member and system stiffness matrices and the load vectors are expressed in incremental (decremental) forms. The updated system stiffness-matrix is sated in terms of stiffness- and deterioration-uncertainties and the updated system load-vector is stated in terms of deterioration- and loading-uncertainties. Using the Neumann expansion solution technique, the inversion of the updated system stiffness matrix is expressed in terms of uncertainty parameters so that the reliability iteration can be performed without requiring repetitive inversion of the stiffness matrix. The deterioration- and uncertainty-update of the stiffness matrix requires resolution of the eigenvalue problem. This problem is reformulated in terms of uncertainty variables and an efficient solution algorithm is presented. An extra uncertainty parameter is used in structural transfer functions to represent damping uncertainties. Having expressed wave forces as functions of uncertainty variables, formulations of transfer functions of displacements and member internal forces are presented in the uncertainty space, which enable the reliability calculation to be efficient and fast. Apart from uncertainties of structural and loading origins, uncertainties arising from environmental origin, which appear in the spectral-analysis, are summarized. These are related to the modeling of random waves and wave-current interactions as well as to the long-term probability-distribution model of the significant wave height. Uncertainties in SCF, damage model (S-N line), non-narrowness of the stress process, long-term probability distribution of sea states and in the damage at which failure occurs (reference damage) are considered in fatigue-related uncertainties. An example is presented to demonstrate the application of the approximate analysis procedure to the mean value response analysis of deteriorated structures.
The Effect of Directional Spreading on Interaction of Focused Wave Groups With a Cylinder
Authors: Buldakov Eugeny V. , Eatock Taylor Rodney , Taylor Paul H.
Published: January 2009

The problem of diffraction of a directionally spread focused wave group by a bottom-seated circular cylinder is considered from the view point of second-order perturbation theory. After applying the time Fourier transform and separation of vertical variable the resulting two-dimensional non-homogeneous Helmholtz equations are solved numerically using finite differences. Numerical solutions of the problem are obtained for JONSWAP amplitude spectra for the incoming wave group with various types of directional spreading. The results are compared with the corresponding results for a unidirectional wave group of the same amplitude spectrum. Finally we discuss the applicability of the averaged spreading angle concept for practical applications.
Evacuation Performance of Davit Launched Lifeboats
Authors: Simo˜es Re´ Antonio , Veitch Brian
Published: January 2009

The capabilities of two marine evacuation systems have been investigated using model experiments in a large test facility at the Institute for Ocean Technology. Tests were done with the widely used conventional davit launched twin-falls lifeboat and a similar system with the addition of a flexible boom. The performance of both systems was evaluated as a function of weather conditions, ranging from calm conditions to storms. In addition, the effects of the configuration of the evacuation station were examined. This included the orientation of the boat at launch and its clearance from the vessel. Evacuation tests were done in intact and damaged conditions. Results of this large experimental campaign are presented and practical applications to emergency preparedness planning and evacuation system design are discussed. This work aims to address a knowledge gap by providing objective, empirical data that can be used by designers, regulators and others in their decisions concerning safety.
Spectral Analysis of Caspian Level Variations
Authors: Lyubushin Alexey A. , van Gelder Pieter H. A. J. M. , Bolgov Mikhail V.
Published: January 2009

The problem of extracting the most common spectral variations within multidimensional time series of Caspian Sea level variation on the shore stations is considered. Accurate data of 15 stations with a sampling time interval of 6 hours over a time period of observations since the beginning of 1977 till the end of 1991 are available for this purpose. The Fourier-aggregated signal method allows extract stationary common harmonics which form 2 groups of tidal sea level variation at the vicinity of 12 and 24 days periods. Besides that a long-periodic common variation was extracted with the period approximately 12.85 years. The non-stationary collective effects within period range from 4 up to 8 days were detected by estimating canonical coherences of multiple time series within moving time window. Non-stationary common effects are associated with influence of wind.
Pressure Test Method of Safety Assessment on Existed Submarine Pipeline
Authors: Jin Wei-Liang , Shao Jian-Wen
Published: January 2009

Submarine pipeline has become a major transportation pattern of oil and gas, as well known, the petroleum is corrosive and harmful to the steel wall of the pipeline. The existed pipelines should be checked after several years in service, so that the remaining service life time can be estimated and the decision of re-using can be made. Several normal test methods are all expensive; some of them are inconvenient and need to stop the service transportation. So a new convenient method, based on on-spot pressure test, is developed to check the pipeline safety without interrupting the service. In this method, first of all, the corrosion state of the pipeline is estimated on the base of corrosion test. Then mechanical analysis is performed to determine the corresponding test pressure of all corrosion state cases. Then the on-spot pressure test is performed, and the test result is a powerful indication of the safety state of pipeline. An Equivalent Reliability Method (ERM) is used to determine corresponding service pressure, which is believed to be safe for continuing service. This method has been used in a pipeline safety assessment of CNOOC. The result showed that the new attempt is pretty reliable, economic and convenient.
Reliability Analysis of Dynamic Stability in Waves
Authors: Soborg Anders Veldt , Friis Hansen Peter
Published: January 2009

The assessment of a ship’s intact stability is traditionally based on a semi-empirical deterministic concept that evaluates the characteristics of ship’s calm water restoring leverarm curves. Today the ship is considered safe with respect to dynamic stability if its calm water leverarm curves exhibit sufficient characteristics with respect to slope at zero heel (GM value), maximum leverarm, positive range of stability and area below the leverarm curve. The rule-based requirements to calm water leverarm curves are entirely based on experience obtained from vessels in operation and recorded accidents in the past. The rules therefore only leaves little room for evaluation and improvement of safety of a ship’s dynamic stability. A few studies have evaluated the probability of ship stability loss in waves using Monte Carlo simulations. However, since this probability may be in the order of 10−4 per ship year such brute force Monte-Carlo simulations are not always feasible due to the required computational resources. Previous studies of dynamic stability of ships in waves typically focused on the capsizing event. In this study the objective is to establish a procedure that can identify “critical wave patterns” that most likely will lead to the occurrence of a considered adverse event. Examples of such adverse events are stability loss, loss of maneuverability, cargo damage, and seasickness. The adverse events related to dynamic stability are considered as a function of the roll angle, the roll velocity, and the roll acceleration. This study will therefore describe how considered adverse events can be combined into a single utility function that in its scale expresses different magnitudes of the criticality (or assessed consequences) of the adverse events. It will be illustrated how the distribution of the exceedance probability may be established by an estimation of the out-crossing rate of the “safe set” defined by the utility function. This out-crossing rate will be established using the so-called Madsen’s Formula. A bi-product of this analysis is a set of short wave time series that at different exceedance levels may be used in a codified evaluation of a vessels intact stability in waves.