bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
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.
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.
A Gender Profile: U.S. General Aviation Pilot-Error Accidents 1982–1985
Authors: Vail Gayle J. 
Published: January 2009

Women in aviation are having an impact on pilot safety records — a beneficial one. Evidence has shown that they are the safer of the genders while flying as Pilot-In-Command in General Aviation Flying. Data was analyzed from the NTSB files for the year 1982–1985. The results found a positive gender factor for females in number, type, and cause of pilot-error related accidents.
Participatory Ergonomics: Current Approaches to Improving Organizational Effectiveness and Quality of Work Life
Authors: Brown Ogden 
Published: January 2009

Participatory ergonomics is an idea whose time has come! There are many approaches which have been utilized by organizations to improve productivity and enhance quality of work life. Participation itself is not a new idea, but because of current organizational and environmental forces for change, new organizational philosophies are emerging which are developed, designed, and operated with participation of the employees concerned and which do result in improved organizational effectiveness and quality of work life. Organizations in the turbulent environments of today must be able to quickly adapt to conditions of change. Many major forces for change have emerged which significantly impact managerial philosophies and behaviors. In this decade, in fact, the rules of business have changed drastically and permanently. Market conditions, foreign competition, and high growth markets are major forces in today's environment along with societal values, composition of the labor force, type of product, and the general business environment itself. An effective approach to management would suggest that it address these forces for change in order to adapt and succeed. No single approach utilizing participatory techniques is universally effective: a contingency approach is advocated. Basic assumptions underlying a contingency model include the notion that no single approach will be effective under all circumstances, and that most approaches utilized today will be effective under a certain set of conditions. It appears that some form of participative management meets current needs primarily because it best suits the labor force, today's technologies, and current societal conditions. The major participative management approaches discussed include quality circles (currently the most popular), job enrichment strategies, cooperative union-management quality of work life programs, gainsharing plans, and the development and operation of self-managing work teams. Also discussed is an emerging innovation in participative management, use of the parallel organization. There are other methods available, to be sure, but these appear to be the principal participative approaches of today. Most participatory approaches and techniques are not new. What is new and very important is the commitment on the part of the organization to adopt what may become organization-wide change strategies through the use of participatory management strategies. The ultimate goal, of course, is to achieve improved organizational effectiveness, product quality, and enhanced quality of work life.
Identifying and Weighting Factors Effecting Work in a Mechanized Office Environment
Authors: Bender Henry E. , Conte Vincent , Bannecker Richard 
Published: January 2009

Decision making concerning the allocation of and distribution of funds in highly automated or computerized offices is often biased by the orientation of the decision maker, and the previous cost benefit analysis of the “system” implementation study. In such an environment, costs are often allocated to hardware or software enhancements, without regard to other factors potentially influencing worker productivity or efficiency. The present study addressed the problem of developing a methodology that would allow for the most expansive listing of factors influencing worker productivity or efficiency. The method used allowed for the greatest amount of input from subject matter experts as well as from system users. The data gathering method is described that facilitated the development of a questionnaire method implemented in a work environment of a major inventory and control system office. The data analysis indicates the functionality of the method, and its usability in a vast number of environments.
NCR 7824 Scanner/Scale: An Ergonomic Solution for the Retail Checkout Environment
Authors: Hoffman Mark S. 
Published: January 2009

Barcode scanning has been instrumental in increasing user productivity and has expanded the capture of product information, and inventory control. The Human Factors Group in NCR has been a major contributor to the design of scanners. The 7824 Scanner/Scale was introduced in 1986. It was designed to provide an ergonomic solution to excessive lifting to weigh produce and meats during the transaction process. This product filled a growing market in customer service; that is to weigh produce and frozen meats within the transaction process rather than require customers to purchase prepackaged fresh foods. The success of the 7824 exceeded expectations because of the influence of ergonomics on market demand. Throughput performances for weighed items improved from 2.1 to 3.4 seconds per item, depending upon workstation configurations. Improvements in throughput are attributed to reductions in physical and psychological workload.
Standing Work: Carpet vs. Concrete
Authors: Rys Malgorzata , Konz Stephan 
Published: January 2009

A significant part of the workforce works with the feet and legs in a relatively static standing position. In an experiment, 20 college students (mean age = 23) stood wearing 2 pairs of socks but no shoes at a table for 240 minutes (120 minutes on carpet on one day and 120 minutes on concrete on another day). Ten subjects stood in the morning and 10 in the afternoon. Foot volume and instep vertical and horizontal circumference and calf circumference did not differ significantly between morning and afternoon or between carpet and concrete. Heart rate did not differ between morning and afternoon but the 95.2 for carpet was significantly lower than the 100.1 for concrete. Perceived comfort ratings were higher for carpet than concrete. Body areas in which comfort decreased the most while on concrete were: lower leg, upper leg, ankle, whole foot, the neck and the shoulder. When the individual factors were combined into a single factor using factor analysis, the 77.7 score (0–100 scale) for carpet was significantly better than the 71.9 for concrete.
Crew Requirements Definition System Demonstration
Authors: Christ Richard E. , Conroy Joseph A. , Robertson Robert E. 
Published: January 2009

The crew requirements definition system (CRDS) is a computer-based methodology designed to minimize the time required to accomplishment any set of tasks while using the fewest resources. It enables analysts and researchers to study in a timely and cost effective manner the effects of varying crew size, task start times (and hence task sequencing), and task allocation to crewmembers or equipment items during the performance of designated missions without the need to observe crews actually performing their duties. The CRDS is programmed in C-language and is designed to be used on an “XT” or faster class of personal computer. The basis of the system is several automated PERT, GANTT, and critical path method calculations. In addition, the system produces other automated calculations and summaries to aid the user. The user should have some knowledge of these operations research techniques to use the system effectively. Also needed is an understanding of the tasks to be performed, the personnel and equipment items available to perform the tasks, each task's duration, and any requirements for task sequencing. The U.S. Army Research Institute for the Behavioral and Social Sciences (ARI) developed the CRDS for the Force Design Directorate at the U.S. Army Combined Arms Combat Development Activity. However, the system is useful in any military or civilian situations in which there is a need to design and evaluate alternative small unit organizational structures. The system can be used whenever the user has some knowledge, or is willing to venture some guesstimates, of the tasks that need to be performed and the capabilities of various assets to perform those tasks.
Dynamic Rules for User Interface Design (DRUID)
Authors: Fox Jeffrey A. , Smith Sidney L. 
Published: January 2009

A well-designed user interface is important for the success and acceptance of any software product. Some experts believe that user interface design can be improved through the application of specific rules translated from general design guidelines. Derivation of design rules from guidelines can be aided by computer tools. But storing guidelines in a computer may offer no advantage over printed text unless the computer also provides aids for selecting and applying design guidelines. DRUED development has been sponsored by The MITRE Corporation as a tool for improving user interface design. DRUID is based on the 944 design guidelines proposed in Smith and Mosier's 1986 Guidelines for Designing User Interface Software. But DRUID's capabilities extend beyond that original text and provide further aids for user interface design. Initial DRUID capabilities demonstrated in 1988 support the review of design guidelines as an “electronic book”, enabling a user to navigate through structured hypertext to find specific guidelines, to find functionally related guidelines, and to browse through guidelines at will. DRUID also permits ready retrieval of related guideline material by cross referencing and via a topical index. Newly developed DRUID capabilities extend that electronic book and move toward a computer-based design tool. DRUID users can now specify relevant guidelines for a system design application and rate the relative importance of those selected guidelines. Proposed future DRUID capabilities will provide functions to rate design compliance with those selected guidelines, to aid the translation of guidelines into specific design rules, and to develop rule-based templates to support modular design of user interface software. DRUID is implemented on the Apple Macintosh II computer with HyperCard software. The user interface for DRUID is designed to accommodate both expert and novice users. A DRUID user can accomplish sequence control either by pointing (via mouse) or by keyed command entries. DRUID computer aids promise to help expedite and reduce the cost of the development of user interface software. Those aids should also help improve the quality and consistency of user interface software through rule-based design.
A Delphi Algorithm that Integrates Knowledge for Expert System Development
Authors: Layton Terre L. , Ellis Newton C. , Huchingson R. Dale 
Published: January 2009

A rapid growth of expert system development in various fields of study will likely occur in this decade. Two prerequisites are needed in order for this to happen: strong social need and technical feasibility. Given that both factors presently exist, a few areas where expert systems can help significantly include: (1) providing an interactively accessible source of updated and well-organized knowledge, and (2) assisting a user in decision making. The current research reviews areas of Artificial Intelligence that relate to the process of knowledge acquisition for expert systems. Until very recently, the primary technique for knowledge acquisition has been the time-consuming process of interviews. Typical techniques include: structured and unstructured interviews, questionnaires, and verbal reporting which incorporates protocol analysis. The functions involved in one or more of the techniques encompass extraction of meaning, data inference, and rule induction coupled with retrospective comment analysis, and behavioral observations. The purpose of the current research is to explore different avenues for data acquisition when dealing with multiple knowledge sources with the objective to develop an automated technique for knowledge acquisition. The Delphi Technique is the primary technique investigated in this study, and the result is the Delphi Manager algorithm which is based on the original version of the Delphi Exercise modified to benefit the expert system development process. Other users of the algorithm include: (1) model verification and validation, (2) forecasting, and (3) opinion polls for policy decision making. Although there are additional uses, the Delphi Manager is primarily formulated for the expert system development process. The Delphi Manager was validated by using an existing knowledge base (KB) that was compiled by a paper and pencil version of the Delphi Technique. This existing KB was part of a dissertation by Randall F. Scott entitled “A Computer Programmer Productivity Prediction Model.” The Delphi Manager has the potential to reduce significantly the time needed to collect and analyze new data. In addition, its user-friendly interface reduces the need for an advanced computer user either to build a questionnaire or to install a help facility. The program provides context sensitive help which is input by the developer through a series of templates. The Delphi Manager is also flexible enough to accommodate anyone from a novice to an advanced programmer. Improvements are suggested that are designed to provide additional program functionality and applications.