bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Air Density Variation on Wind Power Flux
Authors: Essa Khaled S. M. , Etman Soad M. , Embaby M.
Published: August 2004

Wind energy potential is proportional to both air density and the third power of the wind speed averaged over a suitable time period. The wind speed and air density are random variables depending on both time and location. The main objective of this paper is to derive a general wind energy potential formulation, considering the time dependence of both wind speed and air density. A correction factor is derived explicitly in terms of the cross-correlation and the coefficients of variation. The application is performed for environmental and wind speed measurements at the Radiation Protection Department, Nuclear Research Center at Inshas, Egypt.
Cost Analysis Case Study of Grid Integration of Larger Wind Farms
Authors: Tande John Olav Giæver , Uhlen Kjetil
Published: August 2004

This paper assesses the connection of a large wind farm to a regional power system with a weak link to the main transmission grid. The study demonstrates that utilization of modern wind turbine technology and automatic generation control schemes allow operation of large wind farms in weak grids. In the case study considered of a regional power system, the viable wind farm capacity may be increased from 50 to 200 MW.
A Comparative Study of Numerical Schemes and Turbulence Models for Wind Turbine Aerodynamics Modelling
Authors: Baxevanou Catherine A. , Vlachos Nicolas S.
Published: August 2004

This paper is a comparative study of combining turbulence models and interpolation schemes to calculate turbulent flow around a NACA0012 airfoil before and after separation. The calculations were carried out using the code CAFFA of Peric, which was appropriately modified to include more numerical schemes and turbulence models. This code solves the Navier-Stokes equations for 2D incompressible flow, using finite volumes and structured, collocated, curvilinear, body fitted grids. Seven differencing schemes were investigated: central, upwind, hybrid, QUICK, Harten-Yee upwind TVD with five limiters, Roe-Sweby upwind TVD with three limiters, and Davis-Yee symmetric TVD with three limiters. Turbulence effects were incorporated using four turbulence models: standard k-ε, k-ω high Re with wall functions, k-ω high Re with integration up to the wall, and the k-ω low Re model. A parametric study showed that best results are obtained: a) for the k-ε model, when using the Harten-Yee upwind TVD scheme for the velocities and the upwind interpolation for the turbulence properties k and ε, and b) for the k-ω models, when using the Harten-Yee upwind TVD scheme with different limiters for the velocities and the turbulence quantities k and ω. The turbulence models that integrate up to the wall are more accurate when separation appears, while those using wall functions converge much faster.
Modelling Approaches for Flow over a Wind Turbine Blade
Authors: Kramer Richard , Archer Rosalind
Published: August 2004

This work models the aerodynamic performance of a wind turbine blade using computational fluid dynamics and strip theory. The wind turbine blade design was supplied by Twin Turbines Ltd. It is a constant tip-speed ratio design, using stall regulation for power control in winds above the rated speed. The analysis uses the commercial computational fluid dynamics program CFX-5. The software model of the wind turbine blade includes rotation simulated using a rotating domain. The results from this model are compared to the solutions obtained using the strip theory method for wind turbine performance analysis. Finally, the stall regulation of the blade at high wind speeds is investigated, using both CFX and the strip theory model. The results from the two methods show good agreement with each other, and indicate that the regulation effect is likely to be smaller than had been expected by the intended manufacturer, Twin Turbines Ltd.
On-Line Rotor Fault Identification
Authors: Sekhar A. S.
Published: August 2004

The dynamics and diagnostics of rotor with faults have been gaining importance in recent years. In the present study a model-based method is proposed for the on-line identification of faults in a rotor. The fault-induced change of the rotor system is taken into account by equivalent loads in the mathematical model. The equivalent loads are virtual forces and moments acting on the linear undamaged system to generate a dynamic behaviour identical to the measured one of the damaged system. The rotor has been modelled using FEM. Each fault has been identified for its size and location on the shaft for transient and steady rotors. The nature and symptoms of the fault are ascertained using FFT or Wavelet transforms. For on-line rotor fault identification a combined (hybrid) model and signal-based approach is suggested.
Human Performance under the Impact of Continuous and Intermittent Noise in a Manual Machining Task
Authors: Muzammil Mohammad , Hasan Faisal
Published: August 2004

Experimental research was conducted to determine the performance of operators while carrying out industrial tasks in the presence of continuous and intermittent noise. Experimental investigations were carried out at 90, 95, 100 and 105 dB (A) for both types of noise. Two groups of subjects, one having a working experience of 2-7 years and other with 7-12 years were selected for the two studies. The number of units produced was taken as the measure of human performance. The results of the study showed that the level of noise and working experience were statistically significant when the task was carried out in a continuous noise environment. While under intermittent noise conditions effects of noise and work experience and the interaction effect of noise and work experience were all observed to be statistically significant. Investigations also revealed that intermittent noise had a more detrimental effect on performance when compared with continuous noise.
Designing Marine Reserves for Fishery Management
Authors: Meester Geoffrey A. , Mehrotra Anuj , Ault Jerald S. , Baker Edward K.
Published: August 2004

Recent reports have raised serious concerns about the rapid declines of historically productive marine fishery resources and the degradation of essential fish habitats. This global crisis has spurred development of innovative management strategies to rebuild depleted fisheries and marine ecosystems. One highly touted strategy involves the design and creation of marine reserves (areas off limits to extractive uses) to rebuild fisheries and conserve marine biodiversity. In this paper, we propose an integrated sequence of methodologies that provides an objective, quantitative framework for the design of marine reserves in spatially heterogeneous coastal ocean environments.

The marine reserve designs proposed here satisfy the multiple, often-conflicting criteria of disparate resource user groups. This research is the first attempt to explicitly explore the trade-off between the conservation goals of fishery management and coral reef protection and the consumptive interests of commercial and recreational fishing fleets. The spatial distribution and size abundance of reef fish stocks throughout the Florida Keys coral reef ecosystem were estimated from a database consisting of more than 18,000 visual samples taken from 1979 to 2002. These distributions of multispecies abundance and biomass, in conjunction with a geographic database of coral reef habitats, are used to demonstrate an integer goal programming methodology for the design of networks of marine reserves, called plans. Once multiple plans are proposed, a simulation model is used to assess the effects of reserve size and shape on select Florida Keys reef fish populations under dynamic spatial and temporal conditions.
Throughput in Serial Lines with State-Dependent Behavior
Authors: Powell Stephen G. , Schultz Kenneth L.
Published: August 2004

Experimental evidence suggests that production-line workers adjust their work rates in certain situations to prevent idle time. We refer to this as state-dependent behavior, in contrast to the state-independent behavior of machines. In this paper, we develop several models for the state-dependent behavior of production workers. We then use these models to analyze the relation of line length to throughput in these systems. We find that state-dependent behavior makes serial lines more efficient and reduces the detrimental effects that longer line lengths have on throughput. In some cases, line efficiency can actually increase with length. This is a result of a higher percentage of workers having two buffers to provide feedback on the state of the line. Further, we show that workers who both speed up when they are likely to cause idle time for others and slow down when they are likely to become idle themselves improve the overall efficiency of the line.
Are Supply and Plant Inspections Complements or Substitutes? A Strategic and Operational Assessment of Inspection Practices in Biotechnology
Authors: Mayer Kyle J. , Nickerson Jack A. , Owan Hideo
Published: August 2004

This paper theoretically and empirically examines the conventional wisdom in procurement management that often portrays supply inspections and supplier plant inspections as substitutes. We develop a theoretical model that focuses on potential internal spillover costs of the buyer receiving low-quality inputs and external spillover costs should low-quality inputs go undetected. Key to our analysis is the condition of whether a buyer can commit to the intensity of supply inspection. If a buyer cannot commit, supply inspections and plant inspections are substitutes, as widely believed. The two types of inspections, however, may become complements when a buyer is able to commit to the intensity of supply inspection. Complementarity is especially likely when (a) external spillovers are smaller than expected internal spillovers, which depends on the level of buffer inventory, (b) when knowledge sharing between buyer and supplier becomes more effective as the supplier allocates more resources to learning for quality improvement, or (c) when hiding aspects of the production processes is easier for suppliers. We empirically evaluate our model with a new data set drawn from a large biotechnology manufacturer. Empirical results provide broad support for theory, which, we argue, might help to explain variation in inspection practices across industries. Our theory and empirical analysis contribute to the literatures on strategic management, organizational economics, and procurement management by highlighting the organizational and strategic use of inspection practices.
Converting Technology to Mitigate Environmental Damage
Authors: Levi Maurice D. , Nault Barrie R.
Published: August 2004

There are many situations where policy makers would like to induce firms to make a major discrete conversion in production technology to help the environment. This paper examines how heterogeneity in the operating condition of firms' plant and equipment, which cannot be observed by policy makers, can affect the choice between incentives to encourage conversion to a cleaner technology. By relating different conditions of firms' plant and equipment to production costs, extent of environmental damage, and cost of conversion to a cleaner technology, we show when a perfectly discriminating incentive to encourage conversion is not feasible. In addition, we show that firms with plant and equipment in better condition will convert their technology to mitigate their environmental damage, and firms with plant and equipment in poorer condition will not. This and a series of additional results lead to conditions under which an administratively simple uniform lump-sum incentive to switch to cleaner technology is preferable to one based on output. These results and conditions extend to cases where there are network externalities in conversion, and where there is strategic timing in firms' choice of when to convert.
Resource Allocation Based on Efficiency Analysis
Authors: Korhonen Pekka , Syrjänen Mikko
Published: August 2004

The purpose of this paper is to develop an approach to a resource-allocation problem that typically appears in organizations with a centralized decision-making environment, for example, supermarket chains, banks, and universities. The central unit is assumed to be interested in maximizing the total amount of outputs produced by the individual units by allocating available resources to them. We will develop an interactive formal approach based on data envelopment analysis (DEA) and multiple-objective linear programming (MOLP) to find the most preferred allocation plan. The units are assumed to be able to modify their production in the current production possibility set within certain assumptions. Various assumptions are considered concerning returns to scale and the ability of each unit to modify its production plan. Numerical examples are used to illustrate the approach.
Modeling the Impact of Merging Capacity in Production-Inventory Systems
Authors: Iyer Ananth V. , Jain Apurva
Published: August 2004

We model two separate, decentralized systems, each consisting of a warehouse and a production capacity. The demand processes experienced by the systems have different variabilities. The two decentralized systems consider an agreement to pool their production capacities. We examine the impact of the pooling of capacity on inventory costs under two operating rules: (i) the orders from the two warehouses are treated in a first-come–first-served manner, and (ii) the orders from the lower-variability warehouse are given nonpreemptive priority.

We examine this issue using an analytical model that integrates base-stock inventory models with queuing models for the production capacity. The higher-variability demand is modeled as a hyperexponential renewal process, and the lower-variability demand is modeled as a Poisson process. In case of pooled capacity, the arrival process at the production queue is the superposition of the two processes. We prove conditions under which the first-come–first-served operating rule will fail to achieve a Pareto improvement over the separate systems because it would increase inventory cost at the lower-variability warehouse. We then show cases under which the high-variability warehouse will see a reduction in inventory cost over the split system even if it accepts lower priority.
The Performance Implications of Media Richness in a Business-to-Business Service Environment: Direct Versus Indirect Effects
Authors: Vickery Shawnee K. , Droge Cornelia , Stank Theodore P. , Goldsby Thomas J. , Markland Robert E.
Published: August 2004

This research examines media richness by modeling face-to-face, telephone, and electronic media as one construct and testing its performance implications. The context is the third-party logistics industry, in which a customer firm allows a service provider to assume responsibility for all or part of a critical business process. This business-to-business service environment is characterized by high levels of complexity (uncertainty, variability, equivocality) and network interdependence, key contextual attributes that enhance media richness' impact. We found a direct effect of media richness on relational performance and through it, indirect effects on satisfaction and loyalty. Furthermore, we found a direct effect of media richness on loyalty, which suggests that service firms in networked relationships provide loyalty-inducing benefits the genesis of which is not in the satisfaction created by the service itself. While past studies have examined the relationship of richness-related constructs and performance, no significant link was found. Our study is the first to demonstrate that media richness can affect firm performance when businesses interact in a complex environment.
ANNIVERSARY ARTICLE: Improving Emergency Responsiveness with Management Science
Authors: Green Linda V. , Kolesar Peter J.
Published: August 2004

While the goal of OR/MS is to aid decision makers, implementation of published models occurs less frequently than one might hope. However, one area that has been significantly impacted by management science is emergency response systems. Dozens of papers on emergency service management appeared in the OR/MS literature in the 1970s alone, many of which were published in Management Science. Three of these papers won major prizes. More importantly, many of these papers led to the implementation of substantially new policies and practices, particularly in policing and firefighting. Much of this work originated in New York City, though many other cities subsequently adopted the resulting models and strategies. In this paper, we look at the context, content, and nature of the research and the factors that led to these early implementation successes. We then track the extent to which these original models are still affecting decision making in emergency response systems. We also examine the pace of development of new OR/MS models and applications in the area. Finally, we look at issues in emergency responsiveness that have emerged recently as a result of the national focus on terrorism and discuss the potential for future OR/MS modeling and application.
Auctions of Homogeneous Goods with Increasing Returns: Experimental Comparison of Alternative “Dutch” Auctions
Authors: Katok Elena , Roth Alvin E.
Published: August 2004

Most business-to-business (B2B) auctions are used to transact large quantities of homogeneous goods, and therefore use multiunit mechanisms. In the B2B context, bidders often have increasing returns to scale, or synergies. We compare two commonly used auction formats for selling multiple homogeneous objects, both sometimes called “Dutch” auctions, in a set of value environments that include synergies and potentially subject bidders to the “exposure” and “free-riding” problems. We find that the descending-price auction, best known for its use in the Dutch flower auctions, is robust and performs well in a variety of environments, although there are some situations in which the ascending uniform-price auction similar to the one used by eBay better avoids the free-riding problem. We discuss the factors that influence each mechanism's performance in terms of the overall efficiency, the informational requirements, the seller's revenue, and the buyer's profit.
Identifying Innovators for the Cross-Selling of New Products
Authors: Kamakura Wagner A. , Kossar Bruce S. , Wedel Michel
Published: August 2004

With recent advances in information technology, most companies are amassing extensive customer databases. The wealth of information in these databases can be useful in identifying those customers most likely to purchase a new product and in predicting when this adoption may take place. This can assist database marketers in determining when individuals should be targeted for the promotion of a new product, which may increase the efficiency of manufacturing and distribution, and assure a faster return on investments. For this purpose, we propose a model that considers the timing of past purchases across multiple product categories and produces estimates of each customer's propensity of ever purchasing in a particular product category and of the timing of their purchases. The model is designed to help managers identify the best prospects for a new offer in one of multiple categories based on generalizations obtained from past offers. The proposed model also provides projections of aggregate penetration for new brands within the database, based on sample estimates.
Campaign Planning and Scheduling for Multiproduct Batch Operations with Applications to the Food-Processing Industry
Authors: Rajaram Kumar , Karmarkar Uday S.
Published: August 2004

We analyze planning and scheduling of multiproduct batch operations in the food-processing industry. Such operations are encountered in many applications including manufacturing of sorbitol, modified starches, and specialty sugars. Unlike discrete manufacturing, batch sizes in these operations cannot be set arbitrarily, but are often determined by equipment size. Multiple batches of the same product are often run sequentially in “campaigns” to minimize setup and quality costs.

We consider a multiproduct, single-stage, single-equipment batch-processing scheme and address the problem of determining the timing and duration of product campaigns to minimize average setup, quality, and inventory holding costs over a horizon. We formulate the deterministic, static version of this problem over an infinite horizon. We show that, in general, a feasible, finite, cyclic solution may not exist. We provide sufficient conditions for the existence of a finite cycle, use single-product problems to provide lower bounds on the costs for the multiproduct problem, and use them to test heuristics developed for this problem. Next, we modify this formulation to incorporate fixed cycles that may be necessary due to factors such as product obsolescence, perishability, or contracts with customers. We do this by allowing for disposal of excess stock so that finite cycles are always feasible, though they might not be optimal; we also develop bounds and heuristic solution procedures for this case. These methods are applied to data from a leading food-processing company. Our results suggest that our methods could potentially reduce total annual costs by about 7.7% translating to an annual savings of around $7 million.
Decision Technologies for Agribusiness Problems: A Brief Review of Selected Literature and a Call for Research
Authors: Lowe Timothy J. , Preckel Paul V.
Published: August 2004

The supply chain in the food and agribusiness sector is characterized by long supply lead times combined with significant supply and demand uncertainties, and relatively thin margins. These challenges generate a need for management efficiency and the use of modern decision technology tools. We review some of the literature on applications of decision technology tools for a selected set of agribusiness problems and conclude by outlining what we see as some of the significant new problems facing the industry. It is our hope that we will stimulate interest in these problems and encourage researchers to work on solving them.
In This Issue
Authors: Lowe Timothy J. , Preckel Paul V.
Published: August 2004

A regular feature of Manufacturing & Service Operation Management, “In This Issue” briefly describes each issue's articles and highlights their contributions.
No more silencing the past: firstgeneration immigrant women as bricoleuses de mémoire in Parle mon fils parle à ta mère and Fatima ou les Algériennes au square by Leïla Sebbar
Authors: McCullough Mary
Published: August 2004

According to Gérard Noiriel, immigrants have almost no place in the national memory of France, which seems to deny that its colonial past is inextricably linked to its current situation regarding North African immigrants and their descendants. In Parle mon fils parle à
ta mere (1985) and Fatima ou les Algériennes au square (1981), Leïla Sebbar places North African immigrant women at the forefront of her narratives. These women construct memory as bricolage, using bits and pieces from their past, and confer it as a legacy to their children,
who in turn absorb it or reject it along with the influence of French culture. The women thus reweave unofficial history; this places them in the shadow of the official ‘grave-keepers’ of memory. In so doing, their places in the margins of society can be viewed as ‘radical
spaces of openness’ rather than closed spaces of victimization.
Raï Story: mémoire et identité
Authors: Bornier Evelyne M.
Published: August 2004

Born at the beginning of the twentieth century, raï has imposed itself as one of the most important forms of expression in North Africa, especially Algeria. Fashioned from a series of chaotic moments, shocks and counter-shocks, raï became, over time, the kind of popular music
we now know. This essay attempts to trace back the socio-historical and cultural paths taken by this music and its artists.
It was and it was not so: Edmond Amran El Maleh remembers Morocco
Authors: Vogl Mary B.
Published: August 2004

The opening formula to stories in Arabic, ‘It was and it was not so ... it happened and it never did,’ reflects the ambivalence of contemporary Moroccan writers towards the recording of history through writing. In his autobiographical novels, particularly Parcours immobile
and Ailen ou la nuit du récit, the Moroccan Jewish writer Edmond Amran El Maleh questions the legitimacy of the ‘official’ and ‘objective’ accounts of the past and offers an alternative to historical narratives. Through metafiction and dialogic voices that unsettle
fixed notions, he suggests that only fictional and oral accounts can capture the complexities of historical and cultural representations. He also examines the role of photographs in the reconstruction process of memory. El Maleh exemplifies his own ideal of a writer who preserves and revives
the past in order to open the way to a better future.
Déambulations aux confins de la langue et de la mémoire collective: le cas d’Assia Djebar
Authors: Hirchi Mohammed
Published: August 2004

Djebar distinguishes herself from other writers of her generation by the primacy she assigns to the feminine in the elaboration of knowledge and the rehabilitation of collective memory. She has shown herself to be a committed writer, determined to rethink the place of women in Muslim
society. Her critical approach is inscribed within an interdisciplinary framework and is impacted by both new historicism and postmodern theories. Her use of metafiction allows her to transgress the theoretical barriers raised by traditional criticism. This transgression is visible in almost
all her works, which show with elegance the impossibility of separating the fictional and the historical. To separate herself from the dominant discourse, Djebar locates herself and her writing entre-rivages. She dialogues with both Western and Oriental cultural traditions. In this study,
special attention will be given to the strategies Djebar uses to re-establish the ancient memory and to rethink the place of women rawiyates (storytellers) in the elaboration of historical discourse.
Safety Symbol Comprehension: Effects of Symbol Type, Familiarity, and Age
Authors: Handcock Holly E. , Rogers Wendy A. , Schroeder Derek , Fisk Arthur D.
Published: August 2004

A new procedure for evaluating symbol comprehension, the phrase generation procedure, was assessed with 52 younger and 52 older adults. Participants generated as many phrases as came to mind when viewing 40 different safety symbols (hazard alerting, mandatory action, prohibition, and information symbols). Symbol familiarity was also assessed. Comprehension rates for both groups were lower than the 85% level recommended by the American National Standards Institute. Moreover, older participants' comprehension was significantly worse than younger participants', and the older adults also generated significantly fewer phrases. Generally, prohibition symbols were comprehended best and hazard alerting symbols worst. In addition, symbol familiarity was positively correlated with symbol comprehension. These findings indicate that important safety information depicted on signs and household products may be misunderstood if presented in symbolic form. Furthermore, certain types of symbols may be better understood (e.g., prohibition symbols) than other types (e.g., hazard alerting symbols) by both younger and older individuals. These findings signify the utility of the phrase generation procedure as a method for evaluating symbol comprehension, particularly when it is not possible or desirable to provide contextual information. Actual or potential applications of this research include using the phrase generation approach to identify poorly comprehended symbols, including identification of critical confusions that may arise when processing symbolic information
Conceptual Issues in the Study of Dynamic Hazard Warnings
Authors: Meyer Joachim
Published: August 2004

This paper presents a conceptual analysis of dynamic hazard warning systems. The normative aspects of responses to warnings are analyzed, and a distinction is made between two forms of responses to a warning system, referred to as compliance and reliance. Determinants of the responses to warnings are identified, and they are broadly classified into normative, task, and operator factors. Existing research on warnings and automation is assessed in view of this conceptual framework, and directions for future research are discussed. Some implications of this analysis for practitioners, designers, and researchers are indicated. Actual or potential applications of this research include recommendations for the analysis, design, and study of dynamic warning systems.
Verification of the Change Blindness Phenomenon While Managing Critical Events on a Combat Information Display
Authors: DiVita Joseph , Obermayer Richard , Nugent William , Linville James M.
Published: August 2004

Change blindness occurs when humans are unable to detect significant changes in objects and scenes after their attention is momentarily diverted. Because change blindness is relevant in many applied settings, the current study investigated the phenomenon in the context of tasks performed by naval command and control system personnel. Operators of such systems are often heavily loaded with concurrent visual search, situation assessment, voice communications, and controldisplay maninpulation tasks at large, physically dispersed tactical situation displays. As the operators' attention shifts from one display to another, it creates an opportunity for changes to occur on unattended screens with potentially negative consequences. Our results show that on a display containing 8 objects of interest, considerable change blindness was demonstrated in that participants required 2 or more selections to correctly identify a changed object on nearly 1/3 of the test trials. Further, operator performance on 15% of the trials was equivalent to randomly guessing with replacement after making 3 incorrect selections. This research underscores the need for developing effective countermeasures to the change blindness phenomenon. Actual or potential uses of this research include interface design of computer workstations for military, nuclear power industry, air traffic control, crisis response center, and hospital emergency room applications.
Effects of Sensory Modality and Task Duration on Performance, Workload, and Stress in Sustained Attention
Authors: Szalma James L. , Warm Joel S. , Matthews Gerald , Dember William N. , Weiler Ernest M. , Meier Ashley , Eggemeier F. Thomas
Published: August 2004

The workload and stress associated with a 40-min vigilance task were examined under conditions wherein observers monitored an auditory or a visual display for changes in signal duration. Global workload scores fell in the midrange of the NASA Task Load Index, with scores on the Frustration subscale increasing linearly over time. These effects were unrelated to the sensory modality of signals. However, sensory modality was a significant moderator variable for stress. Observers became more stressed over time as indexed by responses to the Dundee Stress State Questionnaire, with evidence of recovery in the auditory but not the visual condition toward the end of the watch. This result and the finding that signal detection accuracy - although equated for difficulty under alerted conditions - favored the auditory mode, indicate that display modality and time on task should be considered carefully in the design of operations requiring sustained attention in order to enhance performance and reduce stress. Actual or potential applications of this research include domains in which monitoring is a crucial part, such as baggage screening, security operations, medical monitoring, and power plant operations.
Productivity and Ergonomic Investigation of Bent-Handle Pliers
Authors: Duke Kelly , Mirka Gary A. , Sommerich Carolyn M.
Published: August 2004

Awkward wrist posture is generally considered an occupational risk factor for hand/wrist disorders, leading to the ergonomic design principle of “bend the tool, not the wrist.” Sixteen participants performed a computer jumper installation task and a simple assembly task while productivity, wrist posture, and shoulder posture were measured. The work surface orientation (vertical and 45°) and the level of constraint placed on the user (constrained grip and unconstrained grip) were also varied. The results indicate that the beneficial effects of the bent-handle pliers are task dependent. In the computer jumper task the bent-handle pliers resulted in 5.3% faster task performance, whereas in the assembly task performance was 4.9% faster with the straight-handle pliers. The bent-handle pliers reduced shoulder deviations by 50% in the jumper installation task, and ulnar deviation was reduced by 12% and 22% for the jumper installation task and the assembly task, respectively (all significant at p < .05). However, allowing participants to hold the pliers in a grip configuration of their choosing (unconstrained technique) often reduced these postural benefits. In applying these results to work place design activities, one should recognize that the ergonomic utility of benthandle pliers can be considerable but that the 3-D kinematics characteristics of the task must be considered.
Trapezius Muscle Motor Unit Activity in Symptomatic Participants During Finger Tapping Using Properly and Improperly Adjusted Desks
Authors: Zennaro Daniel , Läubli Thomas , Krebs Denise , Krueger Helmut , Klipstein Andreas
Published: August 2004

Work-related musculoskeletal disorders in the neck-shoulder area and upper extremities are common among computer users, especially women. We comparedtemporal changes of motor unit (MU) activation in the trapezius muscle during finger tapping using both appropriate and inappropriate ergonomic desk adjustments. Sixteen intensive and nonintensive computer users with either moderate or severe musculoskeletal disorders participated in the study. Six-channel intramuscular electromyographic (EMG) signals and 2-channel surface EMG were recorded from 2 positions of the trapezius muscle. A statistically significant increase in activity was observed with a desk adjusted 5 cm higher than appropriate and was attributable mainly to increased duration of MU activity. Participants with severe symptoms activated more MUs, and these were also active longer. In women, on average, MUs were active nearly twice as long as in men during the same tapping task. This study demonstrates that it is possible to evaluate ergonomic topics on the MU level and that incorrectly adjusted office equipment, in addition to motor demands imposed by the work task, results in prolonged activity of MUs. A potential application of this research is an increased awareness that certain individuals who work with incorrectly adjusted office equipment may be at greater risk of developing work-related musculoskeletal disorders.
Right of Way in the Sky: Two Problems in Aircraft Self-Separation and the Auction-Based Solution
Authors: Erev Ido , Barron Greg , Remington Roger
Published: August 2004

There has been a growing movement to give commercial airliners more freedom in choosing their routes and responsibility for detecting and avoiding conflicts. These “free flight” concepts must contain new rules for assigning right of way in potential conflict situations. To evaluate the effect of prospective rules, the current paper derives the expected response of agents who exhibit different levels of sophistication. Traditional game theoretic analysis is used to derive the behavior of rational agents. Computer simulations are used to predict the behavior of boundedly rational reinforcement learners. The results reveal that several seemingly reasonable, straightforward right-of-way rules might lead to undesirable outcomes. These problematic results are robust to the assumed level of rationality. It is shown that these problems can be alleviated by using auctions to resolve competition for right of way. Actual or potential applications of this research include the usage of second price auctions to address right-of-way and similar conflicts
Evaluation of a Computerized Aid for Creating Human Behavioral Representations of Human-Computer Interaction
Authors: Williams Kent E. , Voigt Jeffrey R.
Published: August 2004

The research reported herein presents the results of an empirical evaluation that focused on the accuracy and reliability of cognitive models created using a computerized tool: the cognitive analysis tool for human-computer interaction (CAT-HCI). A sample of participants, expert in interacting with a newly developed tactical display for the U.S. Army's Bradley Fighting Vehicle, individually modeled their knowledge of 4 specific tasks employing the CAT-HCI tool. Measures of the accuracy and consistency of task models created by these task domain experts using the tool were compared with task models created by a double expert. The findings indicated a high degree of consistency and accuracy between the different “single experts” in the task domain in terms of the resultant models generated using the tool. Actual or potential applications of this research include assessing human-computer interaction complexity, determining the productivity of human-computer interfaces, and analyzing an interface design to determine whether methods can be automated.
The Size-Weight Illusion in Team Lifting
Authors: Naylor Yoko K. , Amazeen Eric L.
Published: August 2004

The purpose of these studies was to examine whether or not there is a size-weight illusion when participants lift containers as a team. In Experiment 1, teams of participants lifted a set of 16 containers that varied in mass and size and reported their perceptions of heaviness and volume. In Experiment 2, participants lifted the same containers individually. A size-weight illusion was demonstrated in each experiment: Reports of perceived heaviness decreased substantially as the volumes of the containers increased for both styles of lifting. However, both the magnitude of the illusion and mean perceived heaviness were greater in the team lift. Actual or potential applications of this research include the development of safe lifting guidelines for team lifting.
Synchronization of Traffic Signals as a Means of Reducing Red-Light Running
Authors: Shinar David , Bourla Muki , Kaufman Liat
Published: August 2004

The goal of this study was to determine if traffic signals that are synchronized along a route are associated with fewer red-light violations than traffic signals that are not synchronized. A total 3600 cycles of traffic signals at 12 intersections along 2 major urban arteries were observed. Synchronized intersections were effective in reducing the likelihood of red-light running (RLR) by (a) providing fewer opportunities than nonsynchronized intersections for RLR and (b) having a lower rate of RLR relative to the number of opportunities. After adjustment for the number of opportunities, the odds of entering the intersections in red in synchronized intersections were nearly 1/7 the odds of RLR in nonsynchronized intersections. Congestion reduced the effectiveness of synchronized intersections relative to non-synchronized intersections. Male drivers were slightly more likely to run red lights than female drivers, and the effects of synchronization were fairly constant across age, gender, and the presence or absence of passengers. Actual or potential applications of this research involve signal synchronization to reduce aggressive driving in general and RLR in particular.
Effect of Salinity on the physiological responses of selected lines/variety of wheat
Authors: Ismail A. M.
Published: August 2004

The effect of different concentrations of salinity (NaCl up to 250 mM) was studied on the germination, dry matter production and some relevant metabolic parameters of two lines (Sakha 69 and Sakha 164) and one variety (Stork) of wheat (Triticum aestivumL.). During the germination and seedling stages the experimental lines tolerated lower and moderate doses of salinity, while the variety was significantly retarded at the lower and moderate levels and completely inhibited at higher doses of salinity. The water content remained more or less unchanged in the two lines under saline conditions, whereas in Stork increasing salinity resulted in a significant decrease in water content. A stimulation of the net photosynthetic rate in both lines, Sakha 69 and Sakha 164, was observed at moderate salinity, but the highest levels proved to be inhibitory. In the Stork variety all salinization levels inhibited photosynthetic activity. The respiration rate in the two tested lines was influenced from salinity levels of 150 mM upwards and increased progressively with the salinity level. In Stork plants increasing salinity levels increased the respiration rate. The soluble sugar and soluble protein contents of the lines increased with increasing salinity. The opposite pattern was revealed in the case of Stork. The amino acid content, including proline, increased significantly with an increase in salinity in all tested plants. the potassium/sodium ratio decreased significantly with a rise in salinization.
Importance of agricultural chemistry in multifunctional crop production
Authors: Németh T.
Published: August 2004

agricultural production is a basic, traditional constituent of the Hungarian economy. An importance question nowadays is how the land can be cultivated and agricultural goods produced under the conditions of sustainable development. From the plant nutrition point of view the establishment of an environment-friendly fertilizer recommendation system is essential if sustainable development is to be achieved. Most experts agree that this type of fertilizer recommendation system is able to fulfil the growing demands of a growing population, while keeping the environment in good condition for the next generations. The experts also agree that fertilizer application could not be replaced widely with organic farming alone. An environmentally friendly fertilizer recommendation system has to be sensitive enough to respond to the effects of different conditions, e.g. great spatial variability of soil characteristics, mosaic-like soil cover, climate, crop rotation practices, soil nutrient supply, etc. There was a dramatic change in Hungarian agriculture at the beginning of the 90s, as the result of which the use of fertilizers decreased sharply for several reasons, e.g. privatization, changes in ownership, withdrawal of state subsidies for mineral fertilizers, drought, etc. Both Hungarian agriculture and the country as a whole is now facing two challenges, i.e. to overcome the economic difficulties and to complete the final phase of preparations to join the EU. Land use change scenarios have proved that the natural endowments of Hungary are suitable for integrating agricultural production with environmental and landscape protection and nature conservation.
History of Acta Agronomica Hungarica
Authors: Sutka J.
Published: August 2004

Hungarian agricultural scientists who published new research results in the 1950s generally submitted their manuscripts to Acta Agronomica Hungarica, which also provided a forum for the development of international cooperation. When the journal was established it published original papers, reviews, lectures and short communications on agricultural sciences in English, Russian, German and French. It was edited in Budapest, first by András Somos and later by János Surányi. In 1965 the editorial office was transferred to the Agricultural Research Institute of the Hungarian Academy of Sciences, Martonvásár, where Sándor Rajki converted it into an English language journal and also made substantial changes to its structure. From 1983 Acta Agronomica was edited in the University of Horticulture and Food Industry, Budapest, with István Tamássy and later Pál Kozma as chief editor. After 12 years, in May 1995, the Agricultural Sciences Section of the Hungarian Academy of Sciences again charged the Agricultural Research Institute of the Hungarian Academy of Sciences, Martonvásár, with the editing of the journal, and since 2000 Zoltán Bedő has been the chief editor. The editorial board of Acta Agronomica Hungarica still regards the publication of the results achieved in basic and applied research on agricultural science as its primary task, with the emphasis on crop research. Preference is given to research on physiology, genetics, crop production, plant breeding, cell and molecular biology, nature and environment protection, and the preservation of gene reserves. The professional standard, recognition, market value and time to publication have improved considerably in recent years. This can be attributed partly to the setting up of an International Advisory Board in addition to the Hungarian Editorial Committee, and partly to the computerised editing and to the precise, conscientious work of the reviewers.
Concept for land use based on regular inundation in the contemplated flood storage areas above Szeged (HUNGARY)
Authors: Fodor Z
Published: August 2004

The planned improvements on the Vásárhelyi plan propose the setting up of flood storage areas along the banks of the Hungarian section of the River Tisza. Two main options have been outlined to transform the land-use system of these areas. According to the first option, the present land-use system with a dominant ratio of arable lands would remain and land-users would receive compensation if the land was used for flood control. The second option suggests a change in the structure of land use to establish a system involving regular inundation in these areas. In this case not only extremely high water levels but all floods would be led out onto these flood storage areas. One of the most important conditions for the introduction of this scenario is the flood regime of the River Tisza. This paper analyses the characteristics of this flood regime as it affects the planned flood storage area to be built near Szeged in southern Hungary on an area of approximately 6000 hectares between Baks, Ópusztaszer and Dóc. The statistics predict that the occurrence and duration of the floods could make the regular inundation of this area possible, but the fact that the water often recedes relatively rapidly may necessitate the partial retention of the floods.
Response of two sunflower hybrids to planting dates and densities
Authors: Allam A. Y. , El-Nagar G. R. , Galal A. H.
Published: August 2004

This investigation was carried out at the Experimental Farm of Assiut University during the summers of 2000 and 2001 to study the responses of two sunflower hybrids (Vidoc and Euroflora) to planting dates (May 1st, June 1stand July 1st) and planting densities (55,533, 83,300 and 166,600 plants/ha). The results indicated that the two varieties differed highly significantly in all studied traits except oil yield/ha. The highest seed yield (3.64 t/ha) was obtained with the variety Vidoc. In addition, the results revealed that the planting date exerted a highly significant influence on all vegetative growth traits along with yield and its components. Increasing plant density increased the seed and oil yield/ha. By contrast, the stem diameter, head diameter, 100-seed weight and seed yield/plant decreased with increasing plant density. The interaction between varieties and plant density had a highly significant effect on head diameter. The greatest head diameter (20.06 cm) was recorded for the variety Vidoc planted at lower density. Concerning the interaction between planting density and planting date, the highest seed yield (4.47 t/ha) was obtained from dense plants at the early sowing date, and the highest oil % (45.32) at the late planting date and the lowest plant density. The second order interaction exerted a highly significant influence on stem and head diameter in addition to seed yield/plant, where the highest value (78.13 g/plant) was obtained with the variety Vidoc planted on May 1stat the lowest plant density.