bluuebunny/crossref_metadata_2025 huggingface dataset:
Visual Field Magnification and Touch Perception When Exploring Surfaces With the Index Finger and a Rigid Instrument
Authors: Gonzalez David , Kowalski Kristina , Dubrowski Adam , Carnahan Heather
Published: July 2007

Objective: The aim of this project was to compare texture discrimination when both touch and vision were perturbed. Background: Texture discrimination is important in the workplace. How textures are identified with the finger and with instruments when vision is magnified with lenses or video cameras is unclear. Method: Sandpaper was explored with the index finger or a metal instrument (hemostat), using normal or magnified vision. The forces generated during exploration were measured, and participants rated surface roughness. Results: With the finger, the perception of roughness was unaffected with magnification; with the instrument, magnified surfaces were perceived as rougher ( p < .05). Forces during finger exploration were unaffected by magnification; forces with the instrument increased under magnification ( p < .05). Conclusion: Visual characteristics of the working field can influence the exploration and perception of materials. With the finger, mechanoreceptors that directly detect textures are activated, and with the instrument, receptors sensitive to vibrations are stimulated. Application: The higher forces produced when using instruments under magnification could lead to material damage. Attenuated perception of texture when exploring with tools may lead to difficulty in accurate touch perception. This could create problems in industrial tasks such as grading wool or identifying surface imperfections on manufactured materials, as well as in clinical settings such as dentistry or surgery in which instruments are used during tissue identification.
Spatial Audio Displays Improve the Detection of Target Messages in a Continuous Monitoring Task
Authors: McAnally Ken I. , Martin Russell L.
Published: July 2007

Objective: The detection of target messages in a background of competing speech and the identification of the color/number combinations in those messages were examined in a continuous monitoring task. Background: Previous research has shown that if listeners know when and where to listen, speech-on-speech intelligibility is improved when signals are presented via a 3-D audio display as compared with a diotic display. However, the effect of display type on detection of infrequent target messages in a continuous monitoring task has not been examined. Method: Participants were required to monitor five communications channels conveying messages at random intervals under each of three audio display conditions: diotic, all channels in front, and channels separated in azimuth (3-D). Results: Message detection sensitivity was significantly higher for the 3-D condition than for the in-front condition but did not differ significantly between the in-front and the diotic conditions. There were no differences in response criteria across conditions. Color/number identification sensitivity also was significantly higher for the 3-D condition than for the in-front condition but did not differ significantly between the in-front and the diotic conditions. Conclusion: A 3-D audio display enhances both message detection and message identification in a continuous monitoring task. Application: Three-dimensional audio displays would be particularly beneficial in environments such as aviation, in which the information conveyed to operators via the auditory modality can be crucial to the safe and effective performance of their work.
The Utility of a Virtual Reality Locomotion Interface for Studying Gait Behavior
Authors: Sheik-Nainar Mohamed A. , Kaber David B.
Published: July 2007

Objective: To investigate the effect of optic flow on gait behavior during treadmill walking using an immersive virtual reality (VR) setup and compare it with conventional treadmill walking (TW) and overground walking (OW). Background: Previous research comparing TW with OW speculated that a lack of optic flow (relative visual movement between a walker and the environment) during TW may have led to perceptual cue conflicts, resulting in differences in gait behavior, as compared with OW. Method: Participants walked under three locomotion conditions (OW, TW, and TW with VR [TWVR]) under three walking constraint conditions (no constraint, a temporal/pacing constraint, and a spatial/path-following constraint). Presence questionnaires (PQs) were administered at the close of the TWVR trials. Trials were subjected to video analysis to determine spatiotemporal and kinematics variables used for comparison of locomotion conditions. Results: ANOVA revealed gait behavior during TWVR to be between that of OW and TW. Speed and cadence during TWVR were significantly different from those of TW, whereas knee angle was comparable to that of OW. Correlation analysis of PQ scores with gait measures revealed a positive linear association of the distraction subfactor of the PQ with walking speed during TWVR, suggesting an increase in the sense of presence in the virtual environment led to increases in walking speed. Conclusion: The results demonstrate that providing optic flow during TW through VR has an impact on gait behavior. Application: This study provides a basis for developing simple VR locomotion interface setups for gait research.
Toward Developing an Approach for Alerting Drivers to the Direction of a Crash Threat
Authors: Fitch Gregory M. , Kiefer Raymond J. , Hankey Jonathan M. , Kleiner Brian M.
Published: July 2007

Objective: This study explored the potential for auditory and haptic spatial cuing approaches to alert drivers to the direction of a crash threat. Background: For an automobile equipped with multiple crash avoidance systems, effective cuing of the crash threat direction may help the driver avoid the crash. Because the driver may not be looking in the direction of a visual crash alert, nonvisual crash alerts were explored as an additional means of directing attention to a potential crash situation. Methods: In this in-traffic study, 32 drivers were asked to verbally report alert direction in the absence of any crash threats. Driver localization accuracy and response time were examined as a function of eight alert locations surrounding the vehicle and four directional alert approaches (auditory, haptic, haptic and auditory, and haptic and nondirectional auditory). The auditory directional alert approach used four speakers and broadband alert sounds, and the haptic directional alert approach used vibrations generated at various locations on the bottom of the driver's seat. Results: Overall, relative to the auditory alert approach, the three approaches that included the haptic seat alert component reduced correct localization response times by 257 ms and increased percentage correct localization from 32% to 84%. Conclusion: These results suggest that seat vibration alerts are a promising candidate for alerting drivers to the direction of a crash threat. Application: These findings should facilitate developing a multimodality integrated crash alert approach for vehicles equipped with multiple crash avoidance systems.
Visual Attention in Driving: The Effects of Cognitive Load and Visual Disruption
Authors: Lee Yi-Ching , Lee John D. , Ng Boyle Linda
Published: July 2007

Objective: This study investigates the effect of cognitive load on guidance of visual attention. Background: Previous studies have shown that cognitive load can undermine driving performance, particularly drivers' ability to detect safety-critical events. Cognitive load combined with the loss of exogenous cues, which can occur when the driver briefly glances away from the roadway, may be particularly detrimental. Method: In each of two experiments, twelve participants engaged in an auditory task while performing a change detection task. A change blindness paradigm was implemented to mask exogenous cues by periodically blanking the screen in a driving simulator while a change occurred. Performance measures included participants' sensitivity to vehicle changes and confidence in detecting them. Results: Cognitive load uniformly diminished participants' sensitivity and confidence, independent of safety relevance or lack of exogenous cues. Periodic blanking, which simulated glances away from the roadway, undermined change detection to a greater degree than did cognitive load; however, drivers' confidence in their ability to detect changes was diminished more by cognitive load than by periodic blanking. Conclusion: Cognitive load and short glances away from the road are additive in their tendency to increase the likelihood of drivers missing safety-critical events. Application: This study demonstrates the need to consider the combined consequence of cognitive load and brief glances away from the road in the design of emerging in-vehicle devices and the need to provide drivers with better feedback regarding these consequences.
Learning Headway Estimation in Driving
Authors: Taieb-Maimon Meirav
Published: July 2007

Objective: The main purpose of the present study was to examine to what extent the ability to attain a required headway of 1 or 2 s can be improved through practical driving instruction under real traffic conditions and whether the learning is sustained after a period during which there has been no controlled training. Background: The failure of drivers to estimate headways correctly has been demonstrated in previous studies. Methods: Two methods of training were used: time based (in seconds) and distance based (in a combination of meters and car lengths). For each method, learning curves were examined for 18 participants at speeds of 50, 80, and 100 km/hr. Results: The results indicated that drivers were weak in estimating headway prior to training using both methods. The learning process was rapid for both methods and similar for all speeds; thus, after one trial with feedback, there was already a significant improvement. The learning was retained over time, for at least the 1 month examined in this study. Conclusion: Both the time and distance training of headway improved drivers' ability to attain required headways, with the learning being maintained over a retention interval. The learning process was based on perceptual cues from the driving scene and feedback from the experimenter, regardless of the formal training method. Application: The implications of these results are that all drivers should be trained in headway estimation using an objective distance measuring device, which can be installed on driver instruction vehicles.
Stress Appraisals and Training Performance on a Complex Laboratory Task
Authors: Gildea Kevin M. , Schneider Tamera R. , Shebilske Wayne L.
Published: July 2007

Objective: We investigated whether training performance on a complex laboratory task differs for trainees whose stress appraisals denote challenge or threat. Background: Past research outside a training context found better performance on tasks when stress appraisals denoted challenge (in which perceived situational demands are commensurate with perceived resources) as opposed to threat (in which perceived coping resources fall short of the demands of the stressor). Method: College students performed Space Fortress during 80 3-min practice trials, 20 tests, and posttests (retention, transfer, secondary task interference). Stress appraisals were measured with a two-item scale (Experiments 1—3) or an eight-item scale (Experiment 3) with (Study 1) or without (Experiments 2 and 3) brief hands-on experience. Results: In all experiments, training improved performance and challenged trainees outperformed threatened trainees throughout training as well as on some baseline and posttraining tests. Conclusions: These studies are the first to document that stress appraisals predict training performance. They suggest that little information about a task is needed for appraisals to account for a significant amount of variance (11%) in training performance. Investigating the dynamic interplay of stress appraisals and training will increase the understanding of stress appraisals and of training. Application: Stress appraisals may improve training if used as a screening tool and/or by implementing interventions aimed at changing appraisals from threat to challenge.
An Apparatus to Evaluate the Pace of Baseball Field Playing Surfaces
Authors: Brosnan James T. , McNitt Andrew S. , Schlossberg Maxim J.
Published: July 2007

During a baseball game, the ball will strike the playing surface at a variety of speeds and angles. The speed at which the ball travels after impact with the playing surface has been referred to as the pace of the surface. Wide variations in pace can reduce the safety and playability of baseball field surfaces. Pace can be quantified by measuring the coefficient of restitution. The coefficient of restitution is defined as the ratio of two velocities; the velocity of a baseball after impact with the surface divided by the velocity of the ball prior to impact. An apparatus was developed to measure the coefficient of restitution of a baseball striking various playing surfaces. The apparatus, termed Pennbounce, uses infrared screens to measure the coefficient of restitution of baseballs propelled at varying angles and velocities. Pennbounce was used to measure the pace of traditional synthetic turf (Astroturf), infilled synthetic turf (Fieldturf), natural turfgrass, and skinned infield surfaces. Baseballs were propelled at the surfaces using two velocities and impact angles. Surface pace was highest on traditional synthetic turf, skinned infield, infilled synthetic turf, and natural turfgrass areas, respectively.
Oscillation of first order neutral differential equations of Euler form
Authors: Guan Kaizhong , Shen Jianhua
Published: July 2007

In this paper, we investigate the first order neutral differential equation of Euler form with variable unbounded delay

where 0 ≤
WENO-TVD schemes for hyperbolic conservation laws
Authors: Zahran Yousef Hashem
Published: July 2007

The purpose of this paper is twofold. Firstly we carry out a modification of the finite volume WENO (weighted essentially non-oscillatory) scheme of Titarev and Toro [14] and [15].This modification is done by using two fluxes as building blocks in spatially fifth order WENO schemes instead of the second order TVD flux proposed by Titarev and Toro [14] and [15]. These fluxes are the second order TVD flux [19] and the third order TVD flux [20].

Secondly, we propose to use these fluxes as a building block in spatially seventh order WENO schemes. The numerical solution is advanced in time by the third order TVD Runge–Kutta method. A way to extend these schemes to general systems of nonlinear hyperbolic conservation laws, in one and two dimension is presented. Systematic assessment of the proposed schemes shows substantial gains in accuracy and better resolution of discontinuities, particularly for problems involving long time evolution containing both smooth and non-smooth features.
Cold Summer Temperature Limits Recruitment of Age‐0 Cutthroat Trout in High‐Elevation Colorado Streams
Authors: Coleman Mark A. , Fausch Kurt D.
Published: July 2007

Translocation is a key strategy for conserving native subspecies of cutthroat trout Oncorhynchus clarkii that have declined markedly throughout their native range. Previous research showed that successful translocations of cutthroat trout in high‐elevation southern Rocky Mountain streams were more likely in streams with warm summer water temperature and led to the hypothesis that cold summer temperatures govern translocation success by limiting recruitment. We tested this by measuring the density and size of age‐0 cutthroat trout (greenback cutthroat trout O. c. stomias and Colorado River cutthroat trout O. c. pleuriticus) in six headwater streams in north‐central Colorado that varied in thermal characteristics. Surveys were conducted at peak emergence during 3 years in two widely spaced study reaches in each stream. Fry density increased with Celsius degree‐days accumulated during the growing season but did not vary significantly among years. We used laboratory data on the growth and survivorship of age‐0 cutthroat trout in three temperature regimes that were similar to those studied in the field to determine expected survivorship and size of fry at the start of winter, which occurred several weeks after peak emergence in our warmer reaches and coincided with emergence in colder reaches. Our results support the hypothesis that recruitment of native cutthroat trout in Colorado is limited by cold water temperatures that reduce growth and recruitment. High‐elevation streams, like those studied, that accumulate 900‐1,200 Celsius degree‐days during the growing season afford the best opportunity for cutthroat trout recruitment and translocation success. Streams that provide 800‐900 degree‐days probably sustain recruitment in some years, and those with less than 800 degree‐days are generally unsuitable for translocations because of a greater risk of recruitment failure and the smaller sizes attained by fry by the onset of winter.
Winter Feeding Success of Stream Trout under Different Streamflow and Turbidity Conditions
Authors: White Jason L. , Harvey Bret C.
Published: July 2007

To investigate the relationship between turbidity and trout feeding success in natural systems, we sampled the stomach contents of resident rainbow trout Oncorhynchus mykiss and coastal cutthroat trout O. clarkii clarkii under different streamflow and turbidity conditions during winter in two northwestern California streams (total sample size = 161). Feeding success generally did not differ sharply for fish collected under low versus high streamflow and turbidity conditions. Bioenergetics modeling suggested that feeding success on average did not reach maintenance levels for seven of eight sets of samples, but extensive feeding on oligochaetes during one period of elevated streamflow resulted in positive energy balances. Occasional peaks in food intake could greatly influence the energy budgets and growth of trout in mild‐winter systems. Under some natural conditions, trout appear able to achieve relatively high feeding success when turbidity limits visibility.
Pedigreed Primate Embryonic Stem Cells Express Homogeneous Familial Gene Profiles
Authors: Navara Christopher S. , Mich-Basso Jocelyn D. , Redinger Carrie J. , Ben-Yehudah Ahmi , Jacoby Ethan , Kovkarova-Naumovski Elizabeta , Sukhwani Meena , Orwig Kyle , Kaminski Naftali , Castro Carlos A. , Simerly Calvin R. , Schatten Gerald
Published: July 2007

Human embryonic stem cells (hESCs) hold great biomedical promise, but experiments comparing them produce heterogeneous results, raising concerns regarding their reliability and utility, although these variations may result from their disparate and anonymous origins. To determine whether primate ESCs have intrinsic biological limitations compared with mouse ESCs, we examined expression profiles and pluripotency of newly established nonhuman primate ESC (nhpESCs). Ten pedigreed nhpESC lines, seven full siblings (fraternal quadruplets and fraternal triplets), and nine half siblings were derived from 41 rhesus embryos; derivation success correlated with embryo quality. Each line has been growing continuously for ∼1 year with stable diploid karyotype (except for one stable trisomy) and expresses in vitro pluripotency markers, and eight have already formed teratomas. Unlike the heterogeneous gene expression profiles found among hESCs, these nhpESCs display remarkably homogeneous profiles (>97%), with full-sibling lines nearly identical (>98.2%). Female nhpESCs express genes distinct from their brother lines; these sensitive analyses are enabled because of the very low background differences. Experimental comparisons among these primate ESCs may prove more reliable than currently available hESCs, since they are akin to inbred mouse strains in which genetic variables are also nearly eliminated. Finally, contrasting the biological similarities among these lines with the heterogeneous hESCs might suggest that additional, more uniform hESC lines are justified. Taken together, pedigreed primate ESCs display homogeneous and reliable expression profiles. These similarities to mouse ESCs suggest that heterogeneities found among hESCs likely result from their disparate origins rather than intrinsic biological limitations with primate embryonic stem cells.

Disclosure of potential conflicts of interest is found at the end of this article.
Briefing: Climate change: ICE aims for authority and balance
Authors: Heffernan Seamus
Published: July 2007

Climate change is a vast, complicated and controversial topic. Seamus Heffernan explains how ICE is expending considerable effort in attempting to devise an authoritative and balanced policy to help members, stakeholders and society decide what can and should be done.
Briefing: A changing climate for civil engineering claims
Authors: Hamer Alex , Peters Caroline
Published: July 2007

Though the reasons may not yet be fully understood, all the evidence points to the fact that the world's climate is changing. It is a risk civil engineers can no longer afford to ignore, say Alex Hamer and Caroline Peters of law firm Reynolds Porter Chamberlain.
Ventilation of window interpane cavity aimed at a higher temperature of the inner pane
Authors: Diomidov Mikhail , Nizovtsev Mikhail , Terekhov Viktor
Published: July 2007

An experimental study of the thermal performance of an air-flow window with triple glazing is described. The measurements were carried out in a climatic chamber under conditions close to a winter season. In the experiments, the temperature and heat-flux distributions on each pane surface, and also the air-temperature distribution over the window height at the middle of the ventilated cavity were determined. The thermal performances of forced and naturally ventilated windows with internal cavities of various thicknesses are reported for a wide range of air-flow rates.
Incorrect inverse problem conected with the parameter identification of the heat and mass transfer models
Authors: Boyadjiev Christo
Published: July 2007

A method for inverse problem solution by means of iterative regularization has been developed. A numerical algorithm for solving inverse incorrect problems based on the developed iterative regularization has been proposed.
Prospects for use of micronized coal in power industry
Authors: Burdukov Anatolii , Konovalov Vladimir , Yusupov Talgat
Published: July 2007

Heat-and-power engineering is the basis for industrial development of developed countries and the main energy fuel for plants is coal. The main directions in improvement of coal energy technologies are related with better ignition of powered fuel and with gas and mazut substitution with coal powder. This paper considered the prospects of energy coal enrichment and the method for production of ultrafine coal with the average size of particles about 10-20 microns, and the existing machines for ultrafine coal production. This method increases substantially the velocity of ignition and combustion of pulverized coal flame. The changes of physical and chemical properties of coal after grinding were considered, the processes of ignition, combustion of micronized coal, spaying and stabilization of flame combustion were analyzed in this paper. The problem of ultrafine coal ignition were considered also.
Sulfur self-retention in ash a grain model approach
Authors: Manovic Vasilije , Grubor Borislav , Ilic Mladen
Published: July 2007

A developed overall model for sulfur self-retention in ash during coal particle combustion is presented in the paper. The total sulfur content in char, after devolatilization, is evaluated using a derived correlation. It is assumed that sulfur retention during char combustion occurs due to the reaction between SO2 and the active part of the Ca in the form of uniformly distributed CaO grains. Parametric analysis shows that the process is limited by solid diffusion through the product layer formed on the CaO grains and that the most important coal characteristics which influence sulfur self-retention are coal rank, content of sulfur forms, molar Ca/S ratio and particle radius. The model predicts relatively well the levels of the experimentally obtained values of SSR efficiencies, as well as the influence of temperature, particle size and the surrounding conditions.
Empirical correlation for prediction of the elutriation rate constant
Authors: Stojkovski Valentino , Kostic Zvonimir
Published: July 2007

In vessels containing fluidized solids, the gas leaving carries some suspended particles. This flux of solids is called entrainment, E or carryover and the bulk density of solids on this leaving gas stream is called the holdup. For design we need to know the rate of this entrainment and the size distribution of these entrained particles Rim in relation to the size distribution in the bed, Rib, as well as the variation of both these quantities with gas and solids properties, gas flow rate, bed geometry and location of the leaving gas stream. Steady-state elutriation experiments have been done in a fluidized bed 0,2 m diameter by 2,94 m high freeboard with superficial gas velocities up to 1 m/s using solids ranging in mean size from 0,15 to 0,58 mm and with particle density 2660 kg/m3. When the fine and coarse particles were mixed, the total entrainment flux above the freeboard was increased. None of the published correlations for estimating the elutriation rate constant were useful. A new simple equation, which is developed on the base of experimental results and theory of dimensional analyses, is presented.
Modeling of bubble break-up in stirred tanks
Authors: Zivkovic Goran , Nemoda Stevan
Published: July 2007

The Lagrangian code LAG3D for dispersed phase flow modeling was implemented with the introduction of bubble break-up model. The research was restricted on bubbles with diameter less than 2 mm, i.e. bubbles which could be treated as spheres. The model was developed according to the approach of Martinez-Bazan model. It was rearranged and adjusted for the use in the particular problem of flow in stirred tanks. Developed model is stochastic one, based on the assumption that shear in the flow induces the break of the bubble. As a dominant parameter a dissipation of the turbulent kinetic energy was used. Computations were performed for two different types of the stirrer: Rushton turbine, and Pitch blade turbine. The geometry of the tank was kept constant (four blades). Two different types of liquids with very big difference in viscosity were used, i.e. silicon oil and dimethylsulfoxide, in order to enable computation of the flow in turbulent regime as well. As a parameter of the flow, the number of rotations of the stirrer was varying. As a result of the computation the fields of velocity of both phases were got, as well as the fields of bubble concentration bubble mean diameter and bubble Sauter diameter. To estimate the influence of the break-up model on the processes in the stirred tank a computations with and without this model were performed and compared. A considerable differences were found not only in the field of bubble diameter, but also in the field of bubble concentration. That confirmed a necessity of the introduction of such model. A comparison with the experiments performed with phase Doppler anemometry technique showed very good agreement in velocity and concentration profiles of the gas phase. The results for the average bubble diameter are qualitatively the same, but in almost all computations about 20% smaller bubble diameter was got than in the measurements.
Thermal instability of Walters B' viscoelastic fluid permeated with suspended particles in hydromagnetics in porous medium
Authors: Kumar Pardeep , Singh Jit , Lal Roshan
Published: July 2007

The effect of suspended particles on the thermal instability of Walters B' viscoelastic fluid in hydromantic in porous medium is considered. For stationary convection, Walters B' viscoelastic fluid behaves like a Newtonian fluid. The medium permeability and suspended particles has ten the onset of convection whereas the magnetic field postpones the onset of convection, for the case of stationary convection. The magnetic field and viscoelasticity intro duce oscillatory modes in the system which was non-existent in their absence.
The efficiency of a dynamically insulated wall in the presence of air leakages
Authors: Kalagasidis-Sasic Angela
Published: July 2007

The movement of air in and through the building envelope often plays a leading role in the transport of heat and moisture into the building. It is caused by pressure and temperature variations around the building envelope inbuilt ventilation system, occupancy, etc. In order to improve the energy consumption, alternative designs for the ventilation systems are considered. One of them is a dynamically insulated wall as an inlet unit for the supplying air. In order to predict the performance of a dynamically insulated wall, it is necessary to make an analysis of the building as a system. This paper presents such system analysis which takes into account the interaction between the building components and indoor and outdoor climate, both in terms of the air leakage and heat and mass transfer to and from the building components. It is shown that, in the presence of air leakages (unintentional openings) in the enclosure of the building, the efficiency of the dynamic insulation is significantly decreased.
Modelling of dynamics of combustion of biomass in fluidized beds
Authors: Saastamoinen Jaakko
Published: July 2007

New process concepts in energy production and biofuel, which are much more reactive than coal, call for better controllability of the combustion in circulating fluidized bed boilers. Simplified analysis describing the dynamics of combustion in fluidized bed and circulating fluidized bed boilers is presented. Simple formulas for the estimation of the responses of the burning rate and fuel inventory to changes in fuel feeding are presented. Different changes in the fuel feed, such as an impulse, step change, linear increase and cyclic variation are considered. The dynamics of the burning with a change in the feed rate depends on the fuel reactivity and particle size. The response of a fuel mixture with a wide particle size distribution can be found by summing up the effect of different fuel components and size fractions. Methods to extract reaction parameters form dynamic tests in laboratory scale reactors are discussed. The residence time of fuel particles in the bed and the resulting char inventory in the bed decrease with increasing fuel reactivity and differences between coal and biomass is studied. The char inventory affects the stability of combustion. The effect of char inventory and oscillations in the fuel feed on the oscillation of the flue gas oxygen concentration is studied by model calculation. A trend found by earlier measurements is explained by the model.
Diffusion models and scale-up
Authors: Boyadjiev Christo
Published: July 2007

A model for transfer processes in column apparatuses has been done. The model may be modified for different apparatuses as columns with (or without) packet bed, two (or three) phase airlift reactors and fluidized bed reactors. The mass transfer is result of different volume reactions as a chemical, photochemical, biochemical or catalytic, reactions, or interphase. mass transfer. The using of the average velocities and concentration permit to solve the scale-up problems. A hierarchical approach for model parameter identification has been proposed.
Multi-criteria optimization of construction technology of residential building upon the principles of sustainable development
Authors: Mulavdic Esad
Published: July 2007

Between various building materials and technology solutions for structural and architectural realization of residential building as well as various effects in use period we do not know which of variants gives the best performance from sustainable development point of view. This paper aims to give a model for optimization of housing construction technology based on some aspects of sustainable development as a set of multi-criteria: energy consumption of building, - renewable resource use, and - air pollution by CO2 emission. The model uses the multi-criteria compromise ranking technique. As a result we take he rank-list of variants and then we can select the best ones or several better variants. This diversity of acceptable solutions gives opportunity to meet future housing demand depending to different possibilities and interests of user, but by environmentally sustainable manner. This paper gives case study of some typical single-family houses in Bosnia and Herzegovina.
Advanced thermodynamics metrics for sustainability assessments of open engineering systems
Authors: Sekulic Dusan , Sankara Jayasankar
Published: July 2007

This paper offers a verification of the following hypotheses. Advanced thermodynamics metrics based on entropy generation assessments indicate the level of sustainability of transient open systems, such as in manufacturing or process industries. The indicator of sustainability may be related to particular property uniformity during materials processing. In such a case the property uniformity would indicate systems? distance from equilibrium i.e., from the sustainable energy utilization level. This idea is applied to a selected state-of-the-art manufacturing process. The system under consideration involves thermal processing of complex aluminum structures during controlled atmosphere brazing for a near-net-shape mass production of compact heat exchangers.
CO2 capture and storage in Greece: A case study from komotini ngcc power plant
Authors: Koukouzas Nikolaos , Klimantos Paraskevas , Stogiannis Prokopis , Kakaras Emmanouel
Published: July 2007

The aim of this paper is to examine the possibilities for the abatement of CO2 emissions in the Greek fossil fuel power generation sector. An overview of CO2 capture, transportation, and storage concepts, on which the R&D community is focused, is presented. The implementation of post-combustion CO2 capture options in an existing fossil fuel power plant is then examined and the consequences on the overall plant performance are determined. Finally, the possibilities of transportation and then underground storage of the pure CO2 stream are analyzed taking into account both technical and economical factors. The results of this analysis show that CO2 sequestration is technically feasible for existing fossil fuel fired power plants in Greece. However, substantial reduction in plant efficiency is observed due to increased energy demand of the technologies used as well as in electricity production cost due to capital and operation costs of capture, transport, and storage of CO2. .
Optimization of pulverised coal combustion by means of CFD/CTA modeling
Authors: Filkoski Risto , Petrovski Ilija , Karas Piotr
Published: July 2007

The objective of the work presented in this paper was to apply a method for handling two-phase reacting flow for prediction of pulverized coal combustion in large-scale boiler furnace and to assess the ability of the model to predict existing power plant data. The paper presents the principal steps and results of the numerical modeling of power boiler furnace with tangential disposition of the burners. The computational fluid dynamics/computational thermal analysis (CFD/CTA) approach is utilized for creation of a three-dimensional model of the boiler furnace, including the platen superheater in the upper part of the furnace. Standard k-e model is employed for description of the turbulent flow. Coal combustion is modeled by the mixture fraction/probability density function approach for the reaction chemistry, with equilibrium assumption applied for description of the system chemistry. Radiation heat transfer is computed by means of the simplified P-N model, based on the expansion of the radiation intensity into an orthogonal series of spherical harmonics. Some distinctive results regarding the examined boiler performance in capacity range between 65 and 95% are presented graphically. Comparing the simulation predictions and available site measurements concerning temperature, heat flux and combustion efficiency, a conclusion can be drawn that the model produces realistic insight into the furnace processes. Qualitative agreement indicates reasonability of the calculations and validates the employed sub-models. After the validation and verification of the model it was used to check the combustion efficiency as a function of coal dust sieve characteristics, as well as the impact of burners modification with introduction of over fire air ports to the appearance of incomplete combustion, including CO concentration, as well as to the NOx concentration. The described case and other experiences with CFD/CTA stress the advantages of numerical modeling and simulation over a purely field data study, such as the ability to quickly analyze a variety of design options without modifying the object and the availability of significantly more data to interpret the results. .
Energy efficiency in Serbia national energy efficiency program: Strategy and priorities for the future
Authors: Oka Simeon , Sedmak Aleksandar , Djurovic-Petrovic Maja
Published: July 2007

Energy system in Serbia, in the whole energy chain, from exploitation of primary energy sources, transformations in electric power plants and district heating plants, energy (electric and heat) transmission and distribution to final users, and up to final energy consumption, is faced with a number of irrational and inefficient behavior and processes. In order to fight with such situation National Energy Efficiency Program, financed by the Ministry of Science and Environmental Protection has been founded in 2001. Basic facts about status of energy sector in Serbia, with special emphasis on the energy efficiency and use of renewable energy sources have been given in the review paper published in the issue No. 2, 2006 of this journal. In present paper new strategy and priorities of the National Energy Efficiency Program for the future period from 2006 to 2008, and beyond, is presented. This strategy and priorities are mainly based on the same concept and principles as previous, but new reality and new and more simulative economic and financial environment in energy sector made by the Energy low (accepted by Parliament in 2004) and Strategy of Development of Energy Sector in Republic Serbia up to 2015 (accepted by the Parliament in May 2005), have been taken into account. Also, responsibilities that are formulated in the Energy Community Treaty signed by the South-East European countries, and also coming from documents and directives of the European Community and Kyoto Protocol are included in new strategy. Once again necessity of legislative framework and influence of regulations and standards, as well as of the governmental support, has been pointed out if increased energy efficiency and increased use of renewable energy sources are expected. .
Research and development of efficient, environmentally improved household gas appliances
Authors: Adzic Miroljub , Fotev Vasko , Milivojevic Aleksandar , Djajic Nenad , Ivezic Dejan , Zivkovic Marija , Buljak Vladeta , Vuletic Vojislav , Pesic Slobodan , Bogdanovic Srdjan , Popovic Ratko
Published: July 2007

An experimental research and analysis of performance of three domestic house hold gas appliances was carried out. The objective of this work, based on the conducted analysis of the research data, was to improve the appliances? performance, prefer ably through relative simple modifications, in order to satisfy DIN 4702 emissions and efficiency standards when using different fuels, including natural gas, liquefied petroleum gases and lower quality natural gas. This report summarizes details of this work and how the objectives were achieved. .
Development and designing of machines and technologies for briquette and pellet manufacturing by dry and wet process
Authors: Mihajlovic Emina , Mitic Dragan , Stojiljkovic Mirko
Published: July 2007

In this paper we present achieved results of the Laboratory for Combustion of the Faculty of Occupational Safety in Nis Serbia, obtained by analyzing and designing of technologies and machines for manufacturing of briquettes and pellets by dry and wet process and identification of technological parameters of briquette manufacturing from waste biomass and coals like: humidity and granule, minimal formation pressure, adhesive type and minimal participation, as well as the possibility of designing biobriquettes with physical-chemical and energy properties given in advance. .
The development of turbine-pump aggregate
Authors: Bogdanovic Bozidar
Published: July 2007

With increasing needs for energy, renewable energy sources have been nowadays the one of the main subject of interest all around the world. Therefore, we made an effort to develop a gamma of axial micro turbines, for a purpose of generation of electrical energy on small water derivation, as well as a part of an irrigation turbine-pump aggregate. In this paper are presented constructive solution of a turbine-pump aggregate with micro turbine and standard norm centrifugal pump. Based on project calculation, expected operating parameters are obtained. After defining conceptual solution of the aggregate detailed development of model on computer and numerical simulation of fluid flow in axial turbine are conducted. .
Fuel efficiency of conventional design tractors diesel engines in relation to new design
Authors: Jevtic Jeremija , Gligorijevic Radenko , Borak Djuro
Published: July 2007

Total consumption of all types of energies is rather high nowadays with constant tendency of increasing. Transport section is one of the highest consumers of energy obtained from fossil fuels. It is absolutely clear that the reduction of energy consumption and the protection of environment - exhaust emission reduction, i. e. cleaner air, will be one of the main tasks of automotive industry in the first decades of the 21st century. In spite of its superiority over the petrol engine in respect of the fuel consumption, a diesel engine "suffers" from the increased exhaust emission, particles and NOx first of all and also from the noise and vibrations. The paper gives a review of fuel efficiency of conventional design tractors diesel engines in relation to new design. .
Theoretical analysis and experimental verification of parabolic trough solar collector with hot water generation system
Authors: Valan-Arasu Amirtham , Sornakumar Thambu
Published: July 2007

The modeling of a parabolic trough collector with hot water generation system with a well-mixed type storage tank using a computer simulation program is presented in this paper. This is followed by an experimental verification of the model and an analysis of the experimental results. The maximum difference between the predicted and the actual storage tank water temperature values is found as 9.59% only. This variation is due to the difference between the actual weather during the test period compared to hourly values and the convection losses from the collector receiver, which were not constant as accounted by the computer simulation program. .
Fire safety case study of a railway tunnel: Smoke evacuation
Authors: van Maele , Merci Bart
Published: July 2007

When a fire occurs in a tunnel, it is of great importance to assure the safety of the occupants of the tunnel. This is achieved by creating smoke-free spaces in the tunnel through control of the smoke gases. In this paper, results are presented of a study concerning the fire safety in a real scale railway tunnel test case. Numerical simulations are performed in order to examine the possibility of natural ventilation of smoke in inclined tunnels. Several aspects are taken into account: the length of the simulated tunnel section, the slope of the tunnel and the possible effects of external wind at one portal of the tunnel. The Fire Dynamics Simulator of the National Institute of Standards and Technology, USA, is applied to perform the simulations. The simulations show that for the local behavior of the smoke during the early stages of the fire, the slope of the tunnel is of little importance. Secondly, the results show that external wind and/or pressure conditions have a large effect on the smoke gases inside the tunnel. Finally, some idea for the value of the critical ventilation velocity is given. The study also shows that computational fluid dynamics calculations are a valuable tool for large scale, real life complex fire cases. .
Synthesis and photochromic behavior of some azo-polysiloxanes modified with nucleobases or donor-acceptor groups
Authors: Enea Ramona , Resmeriţă Ana-Maria , Petraru Laura , Grigoraş Cristian , Scutaru Dan , Simionescu Cristofor , Hurduc Nicolae
Published: July 2007

This paper presents the syntheses, characterization and photochromic behavior of some new azo-polysiloxanes modified with uracil, cytosine or nitro-phenolic groups. Taking into consideration the possibility of generating H-bonds or donor/acceptor interactions, this class of materials present a potential applicability in the immobilization of biomolecules and their nano-manipulations. Also, such compounds are capable of producing a fluid phase, with directional flowing capacity. For all these polymers, the molecular modeling simulations have shown disordered structures, which would generate amorphous phases, a very important aspect for molecules’ nano-manipulation. The photochromic behavior in the presence of UV irradiation was also evaluated.
Determinants of Entry Timing: Firm Capabilities and Environmental Conditions
Authors: García Villaverde Pedro M. , José Ruiz Ortega María
Published: July 2007

In this paper, we analyze the influence of the environmental conditions and firm capabilities on the time of entry. We find significant direct and interaction effects. Furthermore, we show that firms develop a pioneer behavior not only when they have the suitable capabilities to take advantage of the perceived opportunities in the industry but also when these firms have key capabilities to maintain their first‐mover advantages, given the perception of unfavorable conditions in the industry.
The endothelium and vascular inflammation in diabetes
Authors: Hartge Martin M , Unger Thomas , Kintscher Ulrich
Published: July 2007

The endothelium releases multiple mediators, not only regulators of vasomotor function but also important physiological and pathophysiological inflammatory mediators. Endothelial dysfunction is caused by chronic exposure to various stressors such as oxidative stress and modified low-density lipoprotein (LDL) cholesterol, resulting in impaired nitric oxide (NO) production and chronic inflammation. Biomechanical forces on the endothelium, including low shear stress from disturbed blood flow and hypertension, are also important causes of endothelial dysfunction. These processes seem to be augmented in patients with Diabetes. In states of insulin resistance and in type 2 Diabetes insulin signalling is impaired. Increased vascular inflammation, including enhanced expression of inter-leukin-6 (IL-6), vascular cellular adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein (MCP-1) are observed, as is a marked decrease in NO bioavail-ability. Furthermore, hyperglycaemia leads to increased formation of advanced glycation end products (AGE), which quench NO and impair endothelial function.

In summary, during the development of diabetes a number of biochemical and mechanical factors converge on the endothelium, resulting in endothelial dysfunction and vascular inflammation. In the presence of insulin resistance, these processes are potentiated and they provide a basis for the macrovascular disease seen in diabetes.