bluuebunny/crossref_metadata_2025 huggingface dataset:
Combinatorial probabilistic chromatin interactions produce transcriptional heterogeneity
Authors: Voss Ty C. , Schiltz R. Louis , Sung Myong-Hee , Johnson Thomas A. , John Sam , Hager Gordon L.
Published: January 2009

Gene regulation often appears deterministic in the average cell population, but transcription is a probabilistic process at the single-cell level. Although many mechanisms are invoked to account for this behavior, it is difficult to determine how cell-to-cell variation in the interactions of transcription factors with target chromatin impact transcriptional output. Here, we use cells that contain a 200-copy tandem array of promoter or reporter gene units to simultaneously visualize transient interaction, equilibrium or steady-state binding of fluorescent-protein-labeled glucocorticoid receptor with its DNA response elements, the recruitment of diverse coregulators, and transcriptional output at the single-cell level. These regulatory proteins associate with target chromatin via a probabilistic mechanism that produces cell-to-cell variability in binding. The multiple steps of this process are partially independent and differ between individual regulators. The association level of each regulator influences the transcriptional output in individual cells, but this does not account for all transcriptional heterogeneity. Additionally, specific combinatorial interactions of the glucocorticoid receptor and coregulators with response elements regulate transcription at the single-cell level. Like many endogenous genes, the average array transcriptional activity evolves over time. This apparently deterministic average temporal promoter progression involves changes in the probability that specific combinatorial glucocorticoid receptor and coregulator interactions will occur on the response elements in single cells. These data support the emerging `return-to-template' transcription model, which mechanistically unifies the observed extremely transient interactions between the transcription factor and response elements, cell-to-cell variability in steady-state association of factors with chromatin, and the resulting heterogeneous gene expression between individual cells.
Investigation into the fluid—structure interaction of a hydraulically damped rubber mount on the basis of finite element analysis
Authors: Wang L-R , Wang J-C , Lu Z-H , Hagiwara I
Published: January 2009

This paper investigates the working process simulation of a hydraulically damped rubber mount (HDM) based on finite element (FE) analysis of the fluid—structure interaction (FSI). The direct computing method of coupled FSI formulation in arbitrary Lagrangian—Eulerian coordinates and the mixed displacement—pressure FE formulation for the incompressible medium, rubber, are adopted. The constitutive law of rubber is determined by FE analysis of incompressible material. A proportion mesh control algorithm helps to overcome fluid mesh distortion. Comparison of the predicted and experimental static elasticities verifies the effectiveness of the presented modelling approach of an HDM. Analysis of fluid pressure—velocity fields and deformation—stress fields of rubber components under typical working conditions clarifies the working process of the HDM, which can help to evaluate the carrying capacity, to identify the chamber volumetric characteristics, and to determine the fluid field distribution and stress distribution of rubber parts for the structural design of the HDM.
Combining experimental data, computational fluid dynamics, and six-degree of freedom simulation to develop a guidance actuator for a supersonic projectile
Authors: Massey K C , Silton S I
Published: January 2009

A joint effort between the Georgia Tech Research Institute and the Army Research Lab successfully used a combination of numerical and experimental results to demonstrate the performance of a guidance actuator for a supersonic projectile. The use of computational and experimental approaches greatly enhanced the understanding of how the actuators worked as well enabled the program to be completed for a lower cost than if either the modelling or the experiments had been neglected. Wind tunnel experiments were used with computational fluid dynamics results to provide aerodynamic coefficients for six-degree of freedom (6-DOF) simulations. The 6-DOF simulations were used to predict the performance of the projectile in the range, thus ensuring that good range data were acquired and reducing the necessary number of set-up rounds. It was found that there were cases where experimental methods were necessary, although the modelling provided the researchers with a greater detail of flow interactions and provided forces that were difficult to measure.
Comparisons of computational fluid dynamics solutions of static and manoeuvring fighter aircraft with flight test data
Authors: McDaniel D R , Cummings R M , Bergeron K , Morton S A , Dean J P
Published: January 2009

As the capabilities of computational fluid dynamics (CFD) to model full aircraft configurations improve, and the speeds of massively parallel machines increase, it is expected that CFD simulations will be used more and more to steer or in some cases even replace traditional flight test analyses. The mission of the US Air Force SEEK EAGLE office is to clear any new weapon configurations and loadings for operational use. As more complex weapons are developed and highly asymmetric loadings are requested, the SEEK EAGLE office is tasked with providing operational clearances for literally thousands of different flight configurations. High-fidelity CFD simulations employing the turbulent Navier—Stokes equations are in a prime position to help reduce some of the required wind-tunnel and/or flight test workload. However, these types of CFD simulations are still too time consuming to populate a full stability and control parameter database in a brute-force manner. This article reviews results previously published by the authors, which validate the ability of high-fidelity CFD techniques to compute static force and moment characteristics of aircraft configurations. A methodology to generate efficient but non-linear reduced-order aerodynamic loads models from dynamic CFD solutions, which in-turn may be used to quickly analyse various stability and control characteristics at a particular flight condition, is introduced, and the results based on the US Air Force F-16C fighter aircraft that exemplify the process are discussed.
A finite-volume method for the conjugate heat transfer in film cooling devices
Authors: Montomoli F , Adami P , Martelli F
Published: January 2009

The present work concerns the activity performed to upgrade an in-house finite-volume computational fluid dynamics solver for computing heat transfer in gas turbine cooling devices. The ‘conjugate simulation’ of fluid heat transfer and metal heat conduction has been considered. To this aim the original code has been coupled to a new one solving the Fourier equation in the solid domain. This modification allows the ‘conjugate heat transfer’ investigation in the fluid and solid domains at the same time. Moreover an external radiation source can be modelled having included an extra term for the energy balance at solid—fluid interface.

The approach has been validated through two different test-cases. The first one is a two-dimensional laminar flow over a flat plate, the second one is a film-cooled plate.

The code uses conformal meshes, without using interpolation functions at the interfaces. This allows the study of configurations more complex than those in the open literature, such as the complete film-cooled stage shown in this work. In this example the complete cooling system of the nozzle has been modelled, including the two plenums and six rows of cooling channels as well. The conjugate heat transfer (CHT) has been evaluated on rotor blades as well.
Storage capacity and containment issues for carbon dioxide capture and geological storage on the UK continental shelf
Authors: Holloway S
Published: January 2009

Carbon dioxide (CO2) can be stored in geological formations beneath the UK continental shelf (UKCS) as a greenhouse gas mitigation option. It can be trapped in subsurface reservoirs in structural or stratigraphic traps beneath cap rocks, as a residual CO2 saturation in pore spaces along the CO2 migration path within the reservoir rock, by dissolution into the native pore fluid (most commonly brine), by reaction of acidified groundwater with mineral components of the reservoir rock, or by adsorption onto surfaces within the reservoir rock, e.g. onto the carbonaceous macerals that are the principal components of coal. Estimates of the CO2 storage capacity of oil and gas fields on the UKCS suggest that they could store between 1200 and 3500×106 t of CO2 and up to 6100×106 t CO2, respectively. Estimating the regional CO2 storage potential of saline water-bearing sedimentary rocks is resource-intensive and no UK estimates have yet taken into account all the factors that should be considered. Existing studies estimate the pore volume and the likely CO2 saturation in the closed structures in a potential reservoir formation but do not take account of the potentially limiting regional pressure rise likely to occur as a result of the very large-scale CO2 injection that would be necessary to make an impact on national emissions. There is undoubtedly great storage potential in the saline water-bearing reservoir rocks of the basins around the UK, but the real challenge for studies of aquifer CO2 storage capacity in the UK is perhaps not to estimate the total theoretical CO2 storage capacity, as this is not a particularly meaningful number. Rather it is to thoroughly investigate selected reservoirs perceived to have good storage potential to a standard where there is scientific consensus that the resulting storage capacity estimates are realistic. This will allow it to be considered as closer to the status of a reserve rather than a resource and will help define the scope for CO2 capture and storage in the UK.
Computational investigation of impeller—diffuser interaction in a centrifugal compressor with different types of diffusers
Authors: Anish S , Sitaram N
Published: January 2009

A computational study has been conducted to analyse the performance of a centrifugal compressor with different types of diffusers under various levels of impeller—diffuser interactions. Vaneless (VLD), vaned (VD), low solidity vaned (LSVD), and partial vaned diffusers (PVD) are used for this purpose. The study is carried out using commercial software ANSYS CFX. The interaction level is varied by varying the radial gap between the impeller and diffuser by keeping the diffuser vane at three different radial locations. Numerical simulations have been conducted for four different flow coefficients. At design flow coefficient maximum efficiency occurs when the leading edge is at R3 (ratio of radius of the diffuser leading edge to the impeller tip radius) = 1.10 for all vane-type diffuser configurations. At below design flow coefficient higher stage efficiency occurs when the diffuser vanes are kept far away ( R3 = 1.15) and at above design flow coefficient R3 = 1.05 gives better efficiency. The highest diffuser pressure recovery coefficient ( Cp) is observed for VD at design flow coefficient. For VLD, the Cp value increases with flow coefficient. In the case of VD and LSVD configurations the exit flow from the impeller is disturbed when the diffuser vanes are closer, and these disturbances are more evident in the last 10 per cent of the impeller flow. In the case of the impeller with PVD the interaction effects are minimum.
Control of combustion in a thermally stabilized burner
Authors: Chaudhuri S , Mukhopadhyay A , Biswas M S , Cetegen B M , Basu S
Published: January 2009

A model has been developed with the assumption of a plug flow reactor that simulates heat transfer originating from the combustion of premixed reactants within a refractory tube. The work depicted in this article successfully implemented a transient one-dimensional coupled model of a plug flow reactor, which finds practical applications in a batch-type heat treatment furnace. All modes of heat transfer, namely conduction, convection, and radiation, were included in the model with single-step global chemistry for combustion of both methane and propane. Effects of variations of parameters such as inlet gas temperature, mass flux, and inlet fuel mass fraction on the gas and tube wall temperature profiles were studied to understand the shift in flame position along the tube length. It is established that the inlet gas temperature or the preheating level is one of the major governing parameters that determines the position of the flame in the tube. Similarly, reduction in mass flowrate shifted the flame location significantly upstream of the tube. It was also observed that the flame temperature exhibits a monotonic decay with depletion in mass flowrate. Results also show that for fixed inlet gas temperature and mass flowrate, the flame location shifts upstream for an increase in inlet fuel mass fraction. Thermally stabilized sustained combustion mode with optimum inlet gas preheating requirement was analysed as a function of mixture stoichiometry and mass flux. Open-loop and closed-loop control schemes were effectively implemented to establish the thermally stabilized scheme of heating and desired flame position within the tube. For open-loop control, with reduction in the mass flowrate (= 0.01 kg/s), an inlet gas temperature as low as 650 K can be maintained for sustaining combustion inside the tube.

The joint variation of these inlet parameters has been well predicted by a correlation developed for a particular aspect ratio for high Reynolds number flows. The problem of absence of combustion and its solution towards stable flame position for tubes having smaller ratio of cross-sectional area to surface area have been addressed, which leads to the study for low Reynolds number flows. In the small Reynolds number flow cases, a thermally stabilized scheme has been successfully implemented that eliminates the necessity of preheating the gas prior to its combustion inside the tube.
Effect of radial location of nozzles on performance of preswirl systems: A computational and theoretical study
Authors: Lewis P , Wilson M , Lock G D , Owen J M
Published: January 2009

This article investigates the effect of the radial location of the inlet nozzles on the performance of a direct-transfer preswirl system in a rotor—stator wheel-space. A commercial code is used to solve the Reynolds averaged Navier—Stokes equations using a high-Reynolds-number k-ε/ k-ω turbulence model with wall functions. The three-dimensional steady-state model has previously been validated against experimental results from a scale model of a gas turbine rotor—stator system. Computations are performed for three inlet-to-outlet radius ratios, rp/ rb=0.8, 0.9, and 1.0, a range of preswirl ratios, 0.5<β b<2.0, and varying turbulent flow parameters, 0.12<λ T<0.36. The rotational Reynolds number for each case is 106.

The flow structure in the wheel-space and in the region around the receiver holes for each inlet radius is related to the swirl ratio. The performance of the system is quantified by two parameters: the discharge coefficient for the receiver holes ( Cd, b) and the adiabatic effectiveness for the system (θb, ad).

As in previous work, the discharge coefficient is found to reach a maximum when the rotating core of fluid is in synchronous rotation with the receiver holes. As the radius ratio is increased, this condition can be achieved with a smaller value for preswirl ratio βb. A simple model is presented to estimate the discharge coefficient based on the flowrate and swirl ratio in the system.

The adiabatic effectiveness of the system increases linearly with preswirl ratio but is independent of flowrate. For a given preswirl ratio, the effectiveness increases as the radius ratio increases. Computed values show good agreement with analytical results. Both performance parameters show improvement with increasing inlet radius ratio, suggesting that for an optimum preswirl configuration an engine designer would place the preswirl nozzles at a high radius.
Efficiency of injection-moulded polymer composite spur gears
Authors: Senthilvelan S , Gnanamoorthy R
Published: January 2009

Unreinforced nylon 6/6 and 20 per cent carbon-fibre-reinforced nylon 6/6 gears were injection moulded in the laboratory and tested for transmission efficiency using an in-house developed power absorption test rig. Gear tooth temperature was found to increase, resulting in decrease in the transmission efficiency with the number of cycles. The gear tooth surface deterioration during running and reduction in gear tooth stiffness reduce the transmission efficiency. The transmission efficiency of the polymer-steel gear pair is found to be sensitive to the operating load.
Tribological properties and worn surface analysis generated by ashless and phosphorus-free additive in water-based lubricant
Authors: Ma H , Ren T , Zhao Y , Zheng L , Ma C , Han Y
Published: January 2009

Two kinds of ashless and non-phosphorus water-based lubricant additives, dodecenyl succinic acid monoesters and sulphurized dodecenyl succinic acid monoesters, were synthesized from dodecenyl succinic anhydride. The anti-wear and friction-reducing properties of the synthesized additives were evaluated using a four-ball machine, and the worn surfaces were analysed by scanning electron microscopy and X-ray absorption near-edge structure (XANES) spectrocoscopy. The tribological results show that the two kinds of additives exhibit good anti-wear and friction reduction properties as well as or better than oleate, which is an important commercial lubricant additive. The XANES results indicate that the tribofilms mainly consist of adsorbed layers and tribochemical layers, and more sulphate and less sulphide in the films would result in lower friction coefficient. The XANES results also show that thriboheat has important influences on the tribofilms' formation. The mechanism of film formation is proposed.
Review of the lubrication, sealing, and pumping mechanisms in oil- and grease-lubricated radial lip seals
Authors: Baart P , Lugt P M , Prakash B
Published: January 2009

Radial lip seals are successfully used since the 1940s to seal lubricated systems. Despite extensive experimental and theoretical research in the field, it is still not fully clear how these seals function. Experimental studies, found in the public literature, show that the relatively high surface roughness of the seal lip is very important for good and reliable performance. In addition, the pressure distribution under the lip seems to be a critical factor. Six fundamental hypotheses are presented on the lubrication, pumping, and sealing mechanisms to explain the working principles of these seals. It is generally accepted that lubrication results from micro-elastohydrodynamic film build up between the rough seal surface and the shaft. Non-symmetrical tangential deformations of the lip surface are observed during experiments and assumed to act like spiral groove bearings that generate a pumping action and lubricant film. Another hypothesis suggests that the lubricant will behave non-Newtonian under the very high shear rates experienced in operating conditions. This will reduce friction because of shear-thinning and enhances sealing. Macroscopic aids, like hydrodynamic pumping aids and engineered asperity patterns on the shaft, do improve seal performance. Almost all public literature discusses oil-lubricated radial lip seals while many seals are grease-lubricated, especially in certain technical fields. Due to the non-Newtonian behaviour of grease, the lubrication, sealing, and pumping mechanisms are assumed to differ from the oil-lubricated seals. Lower friction and improved protection against contamination are measured, and it is expected that the interest in grease lubrication will rapidly grow in future.
Wear tests of orthopaedic biopolymers with the biolubricant augmented by a visco-supplement
Authors: Joyce T J
Published: January 2009

The lubricant in which both natural and replacement joints must operate is synovial fluid. In vitro wear tests of such prostheses and their biomaterials generally employ a lubricant based on bovine serum, as this contains proteins that have a critical impact in reproducing clinically valid wear rates in the laboratory. However, it is also recognised that bovine serum is not identical to synovial fluid, a key difference being that synovial fluid includes hyaluronic acid but bovine serum does not. Few clinically valid wear tests employing a lubricant that includes hyaluronic acid have been undertaken, and the results have been contradictory. To try and inform these results, a series of wear tests were undertaken using a clinically validated wear screening device to investigate the influence of the addition of hyaluronic acid to the lubricant on the wear rates on two orthopaedic biopolymers. When a clinically used hyaluronic acid solution, Ostenil®, was added to a dilute bovine serum lubricant, it was found that wear factors were not greatly changed compared with dilute bovine serum alone. Additional wear tests were undertaken with Ostenil® added to distilled water. Here, wear was much lower but not clinically valid as transfer films were formed on the test plates.
Theoretical and experimental evaluation of engine bearing performance
Authors: Mufti R A , Priest M
Published: January 2009

Measurements of total engine bearing friction have been carried out on a single-cylinder gasoline engine under fired conditions. The bearing friction was measured indirectly by measuring the total engine friction, piston assembly friction, and valve train friction. Total engine friction was measured via pressure-volume (PV) diagram, whereas piston assembly friction measurement was carried out using the indicated mean effective pressure method. Valve train friction was measured using instrumented camshaft drive pulleys. All the engine auxiliaries were independently driven electrically. Engine bearing friction was measured under different engine operating conditions. The hydrodynamic lubrication regime occurred under most of the engine operating conditions, although at lower engine speeds and higher lubricant temperatures a transition from hydrodynamic to boundary/mix lubrication regime occurred. The effect of two different lubricants SAE 0W20 and SAE 5W30 on engine bearing performance was investigated. The adverse effects of viscous oil at low lubricant temperature were notable, as were the benefits at higher lubricant temperature. Predicted results from a number of engine bearing friction mathematical models have been compared with the experimental results. The comparative study showed that the results generated through the short bearing mobility method under cavitation conditions were close to the experimental data. This experimental system can be used to study bearing design parameters, bearing materials, lubricant chemistry, and engine operating conditions on the bearing performance under realistic conditions in its original environment.
Rheology and high-pressure models for quantitative elastohydrodynamics
Authors: Bair S
Published: January 2009

With the recent appearance of quantitative numerical simulations of the elastohydrodynamic lubrication of concentrated contacts, accurate models that can reproduce the behaviour that has been observed in viscometers for more than 50 years are now needed. This article summarizes the most recent work regarding modelling the temperature and pressure dependence of density, the temperature, pressure, and shear dependence of viscosity, and the pressure and shear dependence of the stress at localization. Thermal conductivity is addressed as well.
Film thickness calculation in elasto-hydrodynamic lubricated line and elliptical contacts: The Dowson, Higginson, Hamrock contribution
Authors: Lubrecht A A , Venner C H , Colin F
Published: January 2009

This article traces the contribution of the Dowson and Higginson work to numerical line contact elasto-hydrodynamic lubricated film thickness prediction and the Hamrock and Dowson contribution to the film thickness prediction in elliptical contacts. Considering the line contact work, this article shows that both the numerical pressure and film thickness results and the curve-fitted film thickness predictions are very accurate, even by today's standards. Concerning the elliptical results, the authors show that the original predictions remain surprisingly accurate but that the issue of the minimum to central film thicknesss ration Hm/ Hc is not yet completely settled.

The article then continues to discuss some limitations of the current models that require additional work, mainly in the area of realistic non-Newtonian lubricant rheology for film thickness predictions and pressure spike analysis.
Performance analysis of rotating externally pressurized air bearings
Authors: Liu Z-S , Zhang G-H , Xu H-J
Published: January 2009

The developed numerical method for solving the isothermal compressible Reynolds equation, which governs the equation of air-bearing analysis, is presented in this study. By using the assumption of mass flow continuity between the bearing clearance and orifices, the non-linear Reynolds equation is derived with the shaft-rotating effect. Newton's method is employed to linearize the Reynolds equation and an iterative successive relaxation process is used to solve for the air film pressure. The proposed method is valid for the analysis of film pressure distribution and load capability. This study gives a theoretical basis for the design of a pocket orifice externally pressurized bearing with the shaft-rotating effect considered, where the aerodynamic and aerostatic effects are coupled. Also, the numerical results indicate the difference between the two kinds of bearings mentioned above.
Young's moduli and wear of cermet coatings
Authors: Kobayashi N , Iwamoto K , Miyazaki Y , Toyama K , Tanaka K , Suzuki N , Toyota T
Published: January 2009

The Young's moduli and wear characteristics of two cermet coatings were evaluated under normal atmosphere. The tested coatings were WC/12 per cent Co and Cr3C2/25 per cent NiCr made by using high-velocity oxygen fuel spraying. The Young's moduli of the coatings were obtained using cantilever bend tests. The wear characteristics were evaluated on a wear test apparatus. The WC/12 per cent Co was superior to Cr3C2/25 per cent NiCr in view of wear resistance. The Cr3C2/25 per cent NiCr coating exhibited low friction at higher temperature. A relation was found between the Young's modulus, hardness, wear resistance, and the offensiveness to the mating material of the tested coatings.
Prediction of film thickness decay in starved elasto-hydrodynamically lubricated contacts using a thin layer flow model
Authors: van Zoelen M T , Venner C H , Lugt P M
Published: January 2009

The prediction of bearing life and performance requires detailed knowledge of the behaviour of elasto-hydrodynamically lubricated (EHL) contacts under varying conditions of load and lubricant supply during many load cycles. Considering starved lubrication, a model is developed that predicts the change of the supply layer to the EHL contact. As the film thickness inside a starved EHL contact is determined by the thickness and distribution of the supply layer, this model can be used to predict the film thickness decay. A formula for the central film thickness decay is obtained for the long-term operation of circular or elliptical contacts under starved conditions. The model is validated experimentally.
Tribological properties of diamond-like carbon coatings in lubricated automotive applications
Authors: Renondeau H , Papke B L , Pozebanchukz M , Parthasarathy P P
Published: January 2009

High-performance coatings are currently used in automotive racing engine applications and are being considered for commercial fleet applications. Because crankcase lubricants were designed for steel surfaces, the change to these new materials may result in different boundary lubrication mechanisms. The aim of the present study is to investigate the friction and wear properties of a series of commercial coatings using simple component-blend lubricants as well as commercial lubricant formulations. The tribological testing revealed that some of the commercial coatings possess advantageous friction and wear properties when compared with steel. The study also stresses that in many cases the use of these coatings results in increasing wear on the steel counterpart.
Component mal-position: The ‘Achilles' heel’ of bearing surfaces in hip replacement
Authors: Isaac G H , Schmalzried T P , Vail T P
Published: January 2009

Total hip replacement (THR) is a very successful procedure, reporting very high success rates. The bearing surface is a key feature of replacement hip joints. It is generally accepted that excessive amounts of wear debris precludes their long-term survivorship. Hip simulator testing has resulted in a new generation of bearing surfaces. In general, these laboratory ( in vitro) improvements in wear performance have resulted in a similar improvement in performance in the body ( in vivo). However, there have been reports of components that have not performed as well as expected and this has been linked to the mal-positioning of components in the body. This article reviews bearing surface options and considers the effects of component mal-position on each of those bearings. There are three bearing surfaces in common use in THR. The effect of component mal-position in all cases is increased levels of wear. In metal/metal bearings this can result in cup rim wear and elevated blood metal ion levels. In metal (or ceramic)/polyethylene bearings wear can be measured radiographically and can result in increased osteolysis. In ceramic/ceramic bearings mal-positioning can result in stripe wear and squeaking.
Contribution margin model applied to the marketing planning of a container liner carrier
Authors: Costa G A A , Brinati M A , Hino C M
Published: January 2009

The implementation of confidential contracts between a container liner carrier and its customers, because of the Ocean Shipping Reform Act (OSRA) 1998, demands a revision in the methodology applied in the carrier's planning of marketing and sales. The marketing and sales planning process should be more scientific and with a better use of operational research tools considering the selection of the customers under contracts, the duration of the contracts, the freight, and the container imbalances of these contracts are basic factors for the carrier's yield. This work aims to develop a decision support system based on a linear programming model to generate the business plan for a container liner carrier, maximizing the contribution margin of its freight.
Modelling axisymmetric cod-ends made of different mesh types
Authors: Priour D , Herrmann B , O'Neill F G
Published: January 2009

Cod-ends are the rearmost part of trawl fishing gears. They collect the catch, and for many important species it is where fish selection takes place. Generally speaking they are axisymmetric, and their shape is influenced by the catch volume, the mesh shape, and the material characteristics. The shape of cod-ends is of importance as it determines mesh opening and consequently influences the selectivity of fish from the cod-end. Selectivity is the process whereby a gear retains large fish and releases small ones. In recent years, as many fish stocks have become more threatened, understanding the selectivity process has become more important. This paper presents a model of the deformation of an axisymmetric cod-end. The twine tension and the catch pressure acting on the knots of each mesh along the cod-end profile are calculated, and a Newton—Raphson scheme is used to estimate the equilibrium position of the netting. The software package developed to solve this problem is freely available. Comparisons are carried out with a previous model and experimental data.
Randomized Equivalence Study Evaluating the Possibility of Switching Hemodialysis Patients Receiving Subcutaneous Human Erythropoietin Directly to Intravenous Darbepoetin Alfa
Authors: Chazot Charles , Terrat Jean Claude , Dumoulin Alexandre , Ang Kim-Seng , Gassia Jean Paul , Chedid Khalil , Maurice Francois , Canaud Bernard
Published: January 2009

Background:

Darbepoetin alfa is an erythropoiesis-stimulating agent (ESA) used either intravenously or subcutaneously with no dose penalty; however, the direct switch from subcutaneous recombinant human erythropoietin (rHuEPO) to intravenous darbepoetin has barely been studied.

Objective:

To establish the equivalence of a direct switch from subcutaneous rHuEPO to intravenous darbepoetin versus an indirect switch from subcutaneous rHuEPO to intravenous darbepoetin after 2 months of subcutaneous darbepoetin in patients undergoing hemodialysis.

Methods:

In this open, randomized, 6-month, prospective study, patients with end-stage kidney disease who were on hemodialysis were randomized into 2 groups: direct switch from subcutaneous rHuEPO to intravenous darbepoetin (group 1) and indirect switch from subcutaneous rHuEPO to intravenous darbepoetin after 2 months of subcutaneous darbepoetin (group 2). A third, nonrandomized group (control), consisting of patients treated with intravenous rHuEPO who were switched to intravenous darbepoetin, was also studied to reflect possible variations of hemoglobin (Hb) levels due to change from one type of ESA to the other. The primary outcome was the proportion of patients with stable Hb levels at month 6. Secondary endpoints included Hb stability at month 3, dosage requirements for darbepoetin, and safety of the administration route.

Results:

Among 154 randomized patients, the percentages with stable Hb levels were equivalent in groups 1 and 2, respectively, at month 3 (86.0% vs 91.3%) and month 6 (82.1% vs 81.6%; difference –0.5 [90% CI –12.8 to 11.8]). Mean Hb levels between baseline and month 6 remained stable in both groups, with no variation in mean darbepoetin dose. Mean ferritin levels remained above 100 μg/L in the 3 groups during the whole study, and darbepoetin was well tolerated.

Conclusions:

This study has shown equivalent efficacy on Hb stability without the need for dosage increase in patients switched directly from subcutaneous rHuEPO to intravenous darbepoetin.
Dosing Nomograms: Silos on a Slope
Authors: Dager William E
Published: January 2009

Developing dosing management guidelines or protocol approaches to pharmacotherapy can provide several benefits for standardization of care. Frequently, clinicians may need to incorporate multiple influencing factors to individualize management. In some cases, preestablished, standardized approaches may create barriers to individualized care, potentially categorizing patients into dosing categories (silos) that minimize their individualized needs. Approaches to managing direct thrombin inhibitor therapy have been recently explored and dosing approaches different from those provided in the prescribing information have been proposed. Considerations regarding individualized management of anticoagulant therapy, including the use of standardized dosing or monitoring protocols, are discussed here.
Public policy and sequential lineups
Authors: Malpass Roy S. , Tredoux Colin G. , McQuiston‐Surrett Dawn
Published: January 2009

The claim that sequential lineups are superior to simultaneous lineups and that our knowledge of sequential lineups is sufficient to warrant their being required by law is reviewed for the validity of both strong and weak claims of sequential superiority, adherence to principles of research design, and the needs of public policy. We conclude, (1) there is little evidence to support the claim that sequential presentation of photos is responsible for lower levels of false identifications, (2) the evidence is weak that the aggregation of factors commonly labeled as the sequential lineup together produce lower levels of false identifications without additional offsetting effects, (3) much of the literature contains several confounds in research design and additional offsetting effects that question its overall utility, (4) recent research shows that the superiority of sequential lineups is restricted to specific ranges on other study design variables, and (5) the corpus of research on sequential lineups does not satisfy the needs of policy sufficiently to justify its mandated use as the required identification procedure throughout the criminal justice system.
Army Materiel Handling Accident Analysis
Authors: McMichael Allen E. , Durbin Dave , Gamache Gerald L.
Published: January 2009

Successful Army operations depend on the efficient handling, storage, and flow of materials. Accidents associated with materiel handling activities not only affect the efficiency of an operation but also endanger the lives of Army personnel. In addition, the annual cost to the Army for materiel handling accidents averages approximately $4,315,836. The high incidence and cost of materiel handling accidents poses significant operational problems for the Army. The Army could make great strides in alleviating these operational burdens as well as meeting its safety goals through concerted accident prevention efforts. The U.S. Army Safety Center is making its first attempt to quantify the system problems in the Materiel Handling Major Problem Areas. Improvements in the design of materiel handling equipment and in supervisory practices and training methods may be applicable both to other government agencies and in the private sector.
Effectiveness of Protective Devices to Prevent Child Drownings in Home Swimming Pools
Authors: Lerner Neil D. , Sedney Catherine A. , Cannon-Bowers Janis
Published: January 2009

Drowning in home swimming pools is one of the leading causes of accidental death for children under age five. This paper considers the effectiveness of protective devices, such as fencing, for the prevention of residential pool child drownings. Empirical studies of barrier effectiveness are limited and methodologically flawed. Current codes and standards suffer serious inadequacies. The typical child drowning scenario is discussed, and an approach to a safety system providing layers of protection is described.
A Safety Risk Evaluation of Vigilance Tasks in the U.S. Surface Mining Industry
Authors: Hudock Stephen D. , Duchon James C.
Published: January 2009

Due to the labor intensive nature of mining, the health, safety, and performance of miners is critical to the success of the industry. The U.S. Bureau of Mines has conducted research on accident risk associated with performance of vigilance tasks in surface mining occupations. Over one-third of all surface mining occupations were judged to require extreme to high levels of vigilance for proper task performance. Through accident data analysis of all reported mining accidents available on the Mine Safety and Health Administration accident data base for the year 1986, it was determined that the occupational accident severity level for those employed in high-vigilance surface mining jobs was about twice that for low-vigilance surface mining occupations, based on actual days lost and statutory days charged. This difference in accident severity level was analyzed with respect to the nature of the task activity involved. It was shown that accident severity is higher for employees in high vigilance groups, even for activities that only require low vigilance to perform. These findings support the conclusion that vigilance demands in mining represent a distinct safety risk which may persist for different types of tasks and activities.
Patrol Car Reduces Driver Reaction Times
Authors: Summala Heikki , Hietamäki Jarkko , Lehikoinen Antero , Vierimaa Jukka
Published: January 2009

This research showed that when having passed a patrol car on the road side, drivers' responses to a cyclist coming from a side road occur at a shorter latency. When stopped and interviewed afterwards, the drivers were not able to veridically estimate the time available for their response.
Memory of Instruction Manual Warnings: Effects of Pictorial Icons and Conspicuous Print
Authors: Young Stephen L. , Wogalter Michael S.
Published: January 2009

The present research sought to determine whether the salience of warning messages would improve the memory of warnings in proceduralized instructions. Subjects studied one of four instruction manuals for a gas-powered electric generator under the guise that they would later operate the generator. In the manual, the appearance of eight different warning messages were altered in two ways: 1) The verbal messages were printed in either conspicuous print (larger with color highlighting) or in plain print (same as the other text). 2) The verbal warning messages were either accompanied by meaningfully-related icons or the icons were absent. Three kinds of memory tests were given to subjects. The results showed that subjects who received the manual containing Conspicuous Print, Icons Present warnings recalled the verbal warning content and the semantic meaning of the icons significantly better than subjects who received one of the other three manuals. Implications for the design of instruction manual warnings are discussed.
Perception of Safety Zone around an Industrial Robot
Authors: Karwowski Waldemar , Rahimi Mansour , Nash David L. , Parsaei Hamid R.
Published: January 2009

Laboratory experiments were performed to investigate human perception of safe zone around an industrial robot. It was shown that an angle of approach toward the robot, the speed of robot motions and exposure to a simulated accident significantly affected the student subjects perception of the safe area around the MH33 robot. On the average, across all approach angles, the subjects selected distances of 49.2 and 70.0 cm from the robot's working envelope, for the accident and non-accident group, respectively.
A Study of Expert Judgment on Human Error Probability
Authors: Zimolong Bernhard , Stolte Barbara
Published: January 2009

An experiment was conducted to derive empirically human error probabilities from a task performed under 12 different conditions. The task was to control a simulated flexible manufacturing scenario (FMS) under three Performance Shaping Factors (PSF): Incentive, workload and event frequency of breakdowns. Six experts with background in human factors assess the relative contribution of each PSF in affecting the likelihood of failure with the multi attribute decomposition technique. The conversion of the assessment values to probabilities was achieved by the use of an empirically derived calibration equation. Results indicate a poor match of empirical HEPs and their estimates and increase the doubts that subjective estimation is a solution to the missing data problem in reliability measurement.
Night Time Recognition of Reflectorized Warning Plates as a Function of Shape and Target brightness
Authors: Zwahlen Helmut T. , Gardner-Bonneau Daryle Jean , Adams Charles C. , Miller Michael E.
Published: January 2009

Two independent studies, each employing 12 subjects sitting in a stationary car on an unused airport runway with low beams on, were conducted to determine the distance at which a shape coded, reflectorized warning plate can be recognized at night as a function of target brightness. Recognition distances were recorded for a balanced combination of 15 experimental conditions consisting of 3 different specific intensity levels of target brightness (high 1080 cd/fc/sq ft at .2 degrees observation angle and −4 degrees entrance angle; medium 305 cd/fc/sq ft and low 105 cd/fc/sq ft) and 5 different shapes of equal area (18 square inches) targets (rectangle, circle, square, triangle, octagon). Study 1 used a car heading angle of 10 degrees to the right while Study 2 used a car heading angle of −3 degrees to the left. Results of these studies indicated that increasing target brightness had either no effect or only a small effect on target recognition distance, and the triangle (the object with the longest sides) was recognized at the largest distance and with the fewest errors. Targets were also recognized further away at the 10 degree car heading angle (less beam illumination) than at the −3 degree car heading angle (near maximum beam illumination). Implications of these results for the design and display of shape coded reflectorized warning plates in both traffic and industrial settings are discussed.
Preliminary Study of Brake Pedal Location Accuracy
Authors: Brackett R. Quinn , Koppa Rodger J.
Published: January 2009

Three experiments of brake pedal location accuracy were conducted using 24 subject drivers. The first experiment tested the accuracy of recall of drivers for the brake pedal location of the vehicle with which they were very familiar. The second experiment examined the accuracy of recall for a brake pedal location with which they had recent practice. The last experiment attempted to determine if practice with one brake pedal location would interfere with the accuracy of reproduction of a newly learned pedal location. The results of the experiments indicate that subject drivers have difficulty in reproducing the location of brake pedals. This difficulty exists for familiar brake pedal locations as well as newly learned brake pedal locations. Further there is an indication that practice with one brake pedal location may influence the accuracy of reproducing the location one newly learned.
Individual Differences in Visual Perceptual Processing: Attention, Intelligence, and Display Characteristics
Authors: Laux Lila F. , Lane David M.
Published: January 2009

Researchers have found little evidence that the ability to identify briefly presented simple stimuli (single letters, symbols) is related to intelligence in normal populations although performance on visual processing tasks which impose a greater attentional load (words, phrases, sentences) has been found to correlate with scores on reading tests. This study assessed the correlation between performance on seven visual processing tasks and intelligence as measured by the Raven's and the Nelson-Denny Reading Test. Intelligence correlated with tasks that required the identification of a confusable target, tasks in which the target was defined by a conjunction of features, and tasks in which the target was defined by its location. Intelligence did not correlate with the ability to identify single targets or targets defined by a single non-confusable feature. Other studies have shown that when attentional load is increased by increasing the number of characters in the display, performance is affected differently for confusable and conjunction targets. Increasing the attentional load reduces the number of hits in the confusable condition and increases the number of false alarms in the conjunction condition. In this study these two measures correlated with intelligence but not with each other, meaning that they assess different aspects of visual perceptual processing efficiency. We conclude that when it is critical to correctly identify targets and to avoid false alarms when monitoring complex displays, targets should not be confusable and should be defined by a single feature. When this is not possible, it is important to select operators who are more efficient at processing confusable and conjunction-defined stimuli.
Validation of a Computer-Based Aviation Secondary Selection System for Student Naval Aviators
Authors: Gibb G.D. , Dolgin D.L.
Published: January 2009

This report describes the validation of an automated aircrew selection test battery that measures cognitive processes, psychomotor skills, and time-sharing abilities. Results indicate that performance-based test measures can be used to predict flight training performance.
Where to from Here? Future Applications of Mental Models of Complex Performance
Authors: Hahn Heidi Ann , Nelson William R. , Blackman Harold S.
Published: January 2009

The purpose of this paper is to raise issues for discussion regarding the applications of mental models in the study of complex performance. Applications for training, expert systems and decision aids, job selection, workstation design, and other complex environments are considered.