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202. The Effect of Spin on the Flight of a Baseball.
- Author
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Nathan, Alan M., Hopkins, Joe, Chong, Lance, and Kaczmarski, Hank
- Abstract
New measurements are presented of the lift on a spinning baseball for speeds in the range 50–110 mph and spins 1500–4500 rpm. The experiment utilizes a pitching machine to project the baseball horizontally; a high-speed motion capture system to measure the initial velocity and angular velocity and to track the trajectory over ∼5 m of flight; and a ruler to measure the total distance traversed by the ball. The lift coefficients are extracted from the data and compared to with previous measurements or parametrizations. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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203. Bending Modes, Damping, and the Sensation of Sting in Baseball Bats.
- Author
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Russell, Daniel A.
- Abstract
The painful sensation of sting in the top hand of a player holding a baseball or Softball bat may be a deterrent to enjoying the game, especially for young players. Several mechanisms for reducing the vibration of bending modes have been implemented in youth baseball bats in order to reduce sting. One method of assessing the effectiveness of these mechanisms is to compare the damping rate they provide for the first two or three bending modes in a bat. Damping rates are compared for several wood, aluminum, composite, and two-piece construction baseball bats, in addition to several bats with special damping control mechanisms. Experimental evidence suggests that damping mechanisms which reduce the vibration of the second bending mode arc preferred by players. A novel dynamic absorber in the knob is shown to effectively reduce the vibration of the second bending mode and minimize the painful sting felt in the top hand. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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204. Experimental Investigations of the Relationship of Baseball Bat Properties on Batted-Ball Performance.
- Author
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Shaw, Rebecca H. and Sherwood, James A.
- Abstract
Laboratory tests are used to investigate the relationship between baseball bat performance and two bat properties: moment of inertia (MOI) and barrel stiffness for aluminum and composite bats. Each bat used in the current study is specifically designed and manufactured to isolate a particular property. Static tests, e.g. three-point bend and barrel compression, are used to characterize the properties of each bat. The natural frequencies of the bat are measured using modal techniques. Dynamic performance testing is done using an air cannon capable of throwing a baseball at collision speeds equal to those seen in field play. For the bats studied, variation in MOI contributed more to performance in the lab than did barrel stiffness. However, the changes in predicted field performance due to the two properties were similar. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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205. Forces Generated in a Climbing Rope During a Fall.
- Author
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Phillips, Andrew, Vogwell, Jeff, and Bramley, Alan
- Abstract
The use of micro-protection is key to the development of the sport of rock climbing as harder, blanker rock faces are attempted. However in many situations the force of a fall will be severe enough to injure a climber or exceed the strength of this equipment and so an improved understanding of the factors affecting maximum impact force and subsequent minimisation of this force is essential for the safe use of micro-protection. A laboratory scale rig has been designed to measure the impact forces generated during simulated simple climbing falls. The results show an increase in force with subsequent falls on the same rope due to irreversible damage, however this effect becomes saturated after a certain number of falls. A simple analysis using a linear rope stiffness is described and its predictions compared with the experimental results. The theoretical force equation is generally found to be valid. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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206. Dynamic Characteristics of Modern Mountain Bikes Rear Linkages.
- Author
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Tempia, Angelo, Subic, Aleksandar, and Pagliarella, Riccardo M.
- Abstract
Recent years have seen a tremendous development of full-suspended mountain bikes, especially for downhill and free-ride market. These mountain bikes strongly rely on the ability of the rear suspension shock absorber to manage extremely large forces and wheel travel. Wheel travel is generally achieved through the geometry of the suspension linkage; whereby forces are counterbalanced by the shock hydraulic and spring. The Sports Engineering Research Group (SERG) at the School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University has investigated the dynamic characteristics of different rear linkages suspension geometry. The kinematic analysis has been performed using different programs. A customised Matlab⠪ code has been developed to analyse in detail the kinematic of the linkages, a MSC.Adams⠪ simulation has been conducted to better understand the kinematic and kinetic behaviour. After-market shock absorbers are becoming more and more popular but how their performance is influenced by the rear linkage geometries is often underestimated or not even considered. The results of this research aim to investigate and compare the dynamic characteristics of rear linkage of modern full-suspended mountain bikes. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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207. A Bond Graph Model of a Full-Suspension Mountain Bicycle Rear Shock.
- Author
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Redfield, Robin and Sutela, Cory
- Abstract
As the sport of mountain biking matures, equipment continually evolves to afford better biking performance, enjoyment, and safety. In the arena of suspension systems, mountain bikes have moved from rigid suspensions with large, knobby tires to front fork suspensions, and finally full suspensions. Suspensions have gone from elastomeric compliance to air and coil springs with adjustable travel. Damping has progressed from fixed to adjustable rebound, compression, and lockout. The current trend is to add force or frequency dependent damping to minimize response of a suspension from pedal input. A bond graph model of a mountain bike rear shock is developed incorporating adjustable rebound/low-speed compression, high-speed compression, and adjustable, compression damping initiation. An air shock with a nitrogen charge is modeled with velocity across the shock as input. The dynamic equations that come from a bond graph model are simulated to predict key responses. Experimental response of the modeled shock is acquired subject to periodic velocity inputs. The experimental response is used to tune the design parameters of the model and for validation. Future use of the model is to better understand the physics and performance of the mountain bike shock and to relate performance to the requirements of expert mountain bikers. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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208. A Study of Aerodynamic Drag and Thermal Efficiency of a Series of Bicycle Helmets.
- Author
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Alam, Firoz, Subic, Aleksandar, and Watkins, Simon
- Abstract
The primary objective of a helmet is to provide head protection during fall or accident, however, thermal comfort and aerodynamic efficiency are becoming important design criteria. Helmet with venting generally increases thermal comfort but decreases aerodynamic efficiency. Therefore, an optimal design for helmet is very important in order to satisfy both aerodynamic and thermal efficiency. The primary objective of this work is to study the aerodynamic efficiency and thermal comfort of a series of current production helmets available in Australia. Aerodynamic drag and thermal comfort was measured under a range wind speeds, yaw and pitch angles and compared. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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209. Effect of Shoulder Compliance on Peak High Bar Forces During the Giant Swing.
- Author
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Sheets, Alison L. and Hubbard, Mont
- Abstract
When a female gymnast model does not include shoulder compliance, a simulated optimal performance of a giant swing on the uneven parallel bars is limited by the maximum force that can be exerted on the hands without slipping from the bar (Sheets and Hubbard 2005). To determine the effect of shoulder compliance on hand force, two four-segment gymnast models including an arm, a torso/head and two leg segments are compared: one in which the shoulder is a rigid pin joint, and one which includes shoulder compliance. Experimental values of shoulder stiffness and damping are determined to best describe 1-D vertical damped oscillations of the gymnast/bar system. Optimum shoulder and hip motions during the swing are calculated to complete the most dismount flight revolutions prior to the mass center (CM) passing a specified landing height. Optimization constraints include maximum bar/hand force, physiologic joint limitations, low bar avoidance, and minimum landing distance from the bar. Shoulder and hip motions result from time varying joint torques that are limited by joint angle, angular velocity, isometric strength, and activation factors. Bar release time and joint torque activations at ten nodes equally spaced throughout the swing are optimized using the downhill simplex method. Joint torque activations at all other times are approximated by cubic splines fit to the ten nodes. Performance limitations due to the slipping constraint are not reduced in the compliant model, even though it is active for a shorter period. The compliant shoulder model also produced fewer flight revolutions than the rigid one, 1.417 vs. 1.478, because the shoulder dissipated energy during the swing and stored it at bar release. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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210. Effect of Horizontal Surface Compliance on Balance Strategies.
- Author
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Kimmel, Wendy and Hubbard, Mont
- Abstract
Balancing on a horizontally compliant surface is examined by comparing the task with successively more complex dynamic models. 1,2 and 3 DOF systems are used to examine the balance strategies (state feedback control laws) needed to maintain stability. The 1 and 2 segment systems use a spring attached at the lowest point of the (lower) segment to model horizontal compliance. Velocities are neglected and only position and angular displacement state variables of the system are fed back to achieve balanced, marginally stable closed loop systems. Regions of stability in the feedback gain space are compared using the Routh-Hurwitz criterion, root locus and other graphical techniques. Boundaries of the stable regions in the feedback gain space are provided by the inequalities satisfied by the gains for positivity of the leading column of the Routh array. Knowledge and feedback of horizontal foot position is not important since it is possible to achieve stability by neglecting it entirely. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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211. A Novel Quantitative Method for the Determination of Wear in an Installed Synthetic Turf System.
- Author
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McLeod, Andy, James, Iain, Blackburn, Kim, and Wood, Gavin
- Abstract
This study focuses on the initial development of an image analysis methodology for quantifying the wear and degradation of synthetic sports turf, post installation, where the carpet/infill system is subjected to systemic abrasion and wear from play and maintenance. The pilot study images the surface of polypropylene fibres, which have been agitated with differing sand infill types, with a scanning electron microscope. The resultant images were analysed to determine the degradation of the extrusion features evident in virgin fibre, and it was found that there was significant, quantifiable wear of the turf fibres after seven days with all test sands. The image data for fibres between 7 and 28 days was dependent upon sand type. Further development of the technique is required for determining the next stage of wear – characterized by pitting of the fibre surface by the sand. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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212. The Mechanical Behaviour of Cricket Soils During Preparation by Rolling.
- Author
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Shipton, Peter, James, Iain, and Vickers, Alex
- Abstract
The nature of the ball – surface interaction in cricket has been identified as critical to the quality and safety of the sport. The requirement for even ball bounce and good pace from a clay loam soil cricket pitch has been successfully characterized and has been observed to be related to soil properties such as dry bulk density, moisture content and organic carbon content. To achieve the required mechanical properties, practitioners manage the compaction of a cricket pitch through the use of smooth steel-wheeled rollers. The relationship between moisture content and the compaction and shear strength was determined for a typical clay loam soil and was found to be significant. The effect of subsequent passes of 4.75 and 5.71 kN on soil dry bulk density was also determined in the soil dynamics laboratory. Maximum dry bulk density was achieved after 20 and 10 passes of each roller, respectively. The roller did not have a significant effect on dry bulk density below 50 mm in the profile. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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213. Studies on the Oblique Impact of a Cricket Ball on a Cricket Pitch.
- Author
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James, David, Carré, Matt, and Haake, Stephen
- Abstract
The cricket pitch is a carefully prepared strip of natural turf of fundamental importance to the play of the game, yet the understanding of the factors that lead to good pitch construction remains limited. In order to ascertain why some cricket pitches are perceived to perform well whilst others cause difficulties, the mechanics of the oblique impact of the ball on the pitch have been explored. This study presents the development of a normal impact model to the oblique impact scenario. A coefficient of dynamic friction and an analysis of the pitch crater were used to predict the ball΄s rebound dynamics. Model parameters were determined from simple surface testing procedures and model predictions were found to be within an acceptable range of divergence from experimental impact measurements. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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214. Measuring Ball Spin Off a Tennis Racket.
- Author
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Goodwill, Simon, Douglas, Jamie, Miller, Stuart, and Haake, Stephen
- Abstract
A series of experiments were carried out in which a spinning tennis ball was projected obliquely at a head clamped racket. In each experiment a different string was used in the racket frame. An automated image analysis algorithm was used to measure the velocity and spin of the ball. It has been found that, for the majority of impacts, the magnitude of the ball rebound spin was dependent on string stiffness. It has been concluded that the string stiffness influences the magnitude of stringbed lateral movement during impact. This differing magnitude of lateral string movement, in turn, influences the amount of ball rebound spin. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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215. Normal Impact of Hollow Balls on Flat Surfaces.
- Author
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Honda, Yoshihisa
- Abstract
Normal impact of hollow balls on flat surfaces is theoretically analyzed and the dynamic deformation of hollow balls is derived as an axisymmetric motion of an elastic spherical shell by using modal expansion method, where variation of contact area is taken into account. Numerical calculations were conducted and the dynamic characteristics are discussed. It is found that the center displacement of the ball possesses nearly a half-sine wave form while the reaction force has a triangular time history. It is also shown that the collision time decreases with increasing initial velocity of the ball. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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216. An Extended Study Investigating the Effects of Tennis Rackets with Active Damping Technology on the Symptoms of Tennis Elbow.
- Author
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Cottey, Robert, Kotze, Johan, Lammer, Herfried, and Zirngibl, Werner
- Abstract
The aim of this research was to determine what effect an active damping tennis racket technology had on players suffering with symptoms of tennis elbow. The study was conducted to verify findings of previous research, which concluded that the symptoms of tennis elbow had been dramatically reduced by playing with a Head rackets containing the Head Chip system⠪ (Kotze et al. 2003). A similar study over an extended period was completed to further substantiate these findings and to test the improved generation of `Chip΄ rackets. This study used two versions of the Head Protector Oversize tennis rackets; both containing piezo ceramic fibres integrated with the electronic Chip system⠪, but only half with the chip ˵active″, thus providing a control. The subjects were male and female experienced tennis players diagnosed with either acute or chronic tennis elbow. They were given unspecified rackets to facilitate a blind study, and the subjects΄ elbow condition was medically assessed and recorded over an extended period of time. Results of the study indicated that for the players who were initially diagnosed with acute tennis elbow, a large improvement in their condition was recorded for those using the active rackets, whilst the players with the control rackets showed little improvement in their condition. Similar results were found for the players diagnosed with chronic tennis elbow although to a lesser extent; those using rackets with active chips showed an overall improvement, whilst the players with the control rackets again showed little sign of improvement. The results of the study have shown that an active damping technology, when applied to a tennis racket, can reduce the symptoms of both acute and chronic tennis elbow. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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217. So you think you know the ropes? White Water Rescue Ropes and Techniques.
- Author
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Barker, Matt
- Abstract
Recent equipment failures during simulated white-water rescues have shown the need for detailed measurement of the loads created and the loads that can be safely sustained by the equipment currently in use for white water rescue. This research experimentally finds out; what are the potential forces involved in a white-water rescue? What forces can a three-person rescue team generate? Which of the ropes on the market are suitable for the demands of white-water rescue? Which of the current mechanical advantage rescue techniques are best suited to the equipment available? Are there any experimental techniques that could improve the force generation and safety of the rescue system? Weak points in the complete rescue system are highlighted. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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218. FrontMatter.
- Author
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Moritz, Eckehard Fozzy and Haake, Steve
- Published
- 2006
219. Validation of a Full-Body Computer Simulation of the Golf Drive for Clubs of Differing Length.
- Author
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Kenny, Ian C., Wallace, Eric S., Brown, Desmond, and Otto, Steve R.
- Abstract
The aim of the present study was to validate a full-body computer simulation of a golfer΄s swing for driving clubs. An elite male golfer performed 24 shots in a laboratory, comprised of 8 trials using each of three drivers of different shaft length (46", 48", & 50"). A 5-camera MAC
TM system operating at 240 Hz collected kinematic data which was subsequently used to drive the model utilising ADAMS/LifeMOD software. Additional skin markers were used for model validation. A large-scale musculoskeletal human model was constructed, with a parametric model of a driver. Inverse and forward dynamics calculations were performed with the imported experimental motion data in order to generate model movement. A commercially available launch monitor recorded experimental eclubhead and launch conditions. There was a very high level of agreement (r=0.995) between experimental kinematic data and the predicted trjectory splines of the model. There was also a high level of correlation (r=0.989) between the model predicted mean values for clubhead speed and the experimental values for each of the club lengths, both demonstrating increased clubhead velocity as club length increased. Muscle contraction force output by the model showed a significant difference (p≤0.001) between driver simulations, demonstrating its capability to illustrate the link between gross muscle force production and club length, as evidenced by the increased force output for the longest shafted club. [ABSTRACT FROM AUTHOR]- Published
- 2006
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220. Measurement of Hand Palm Pressures in ˵La Pelota Vasca″ Game.
- Author
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Gámez, Javier, Rosa, David, Alcántara, Enrique, Martínez, Antonio, Such, María José, Durá, Juan Vicente, Prat, Jaime, and Ramiro, José
- Abstract
˵Pelota Vasca″ is a traditional sport coming from the País Vasco with a long history and different modalities. In one of them the ball is hit with the hand against a wall placed in front of the players. A high incidence of hand injuries is found in this sport which has been related to high impact loads and to not adequate protection. Nevertheless, there is not knowledge about biomechanical parameters as impact forces in the hand, hand pressure distribution and others that would be required for an adequate protection design. The purpose of this study was to measure the hand impacts magnitude and distribution when playing ˵Pelota Vasca″. Nine high level players took part in the study. A pneumatic canon was used to throw the ball at 80 km/h speed, that was controlled by two photocell gates. The ball rebounded first against the wall and then on the floor before to be hit by the player. The players hand was equipped with an instrumented glove especially developed for this study. It included 8 piezoelectric sensors distributed according to hand functional anatomy and considering the hitting areas of the hand. Specific software was developed to compute peak pressure at each sensor which was stored for further statistical analysis. The maximum recorded pressure ranged between 4020 kPa and 4378 kPa, at the 2nd and 3rd metacarpal heads respectively. Those values are very high, similar to plantar pressures recorder for speed athletes during maximal speed running, what suggest that the current protection should be improved to reduce pressures. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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221. Time-Resolved Measurements of Grip Force During a Golf Shot.
- Author
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Schmidt, Erin, Roberts, Jonathan, and Rothberg, Steve
- Abstract
Twenty golfers of varying ability took ten shots each with a standard golf club fitted with thin-film force sensors at the grip. Force was monitored at 84 locations, with the moment of impact determined for each shot. Evaluation of the sensor outputs has shown that each player has a grip force signature, i.e. total grip force throughout each shot is very repeatable for a given player, but varies considerably between players. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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222. VeloVent – An Inner City Traffic System for Active People.
- Author
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Müller, Maximilian, Senner, Veit, and Krohn, Michael
- Abstract
The presented concept of a new traffic system for metropolitan areas ˵VeloVent″ suggests a number of innovative developments that may help to solve two major problems of these areas – too much motorized traffic and poor physical health of the citizens. The idea is based on human powered vehicles which run through a tube network with transparent covers (i.e. shopping centers, major company facilities, parks, university campus) are connected by the tube. Emphasis was put on the premises and results of human powered VeloVent vehicles for different transportation purposes in the urban environment. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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223. Using CFD to Understand the Effects of Seam Geometry on Soccer Ball Aerodynamics.
- Author
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Barber, Sarah, Haake, Stephen J., and Carré, Matt
- Abstract
As the performance of athletes and their equipment is pushed to new limits, the importance of understanding the behaviour of sports balls is becoming increasingly apparent. Athletes and equipment manufacturers may try to maximise the distance travelled by a ball (e.g. golf, rugby) or unexpectedly swerve a ball to deceive the opposition (e.g. soccer, cricket, baseball). It is known that the surface geometry, spin and Reynolds number of a ball greatly affect its flight through the air, and this work focuses on understanding the effects of surface geometry. Computational Fluid Dynamics (CFD) has been used to help with the design and development of sports balls, firstly by understanding the details of the flow close to the surface, and secondly by attempting to characterise the surface geometry. CFD studies have been conducted on a smooth sphere and four different soccer balls, including a 1/3 scale model soccer ball and a real ball. The results have been compared to previous wind tunnel results of these balls, and the drag coefficients show consistent trends. It was found that the seam width and sharpness have a large effect on the ball΄s aerodynamic behaviour. Various other balls have been scanned and will be modelled in the future. These results will be combined with trajectory methods in order to accurately simulate the flight of any given sports ball through the air, with any given input condition. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
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224. Optimization of a Recurve Bow Riser Using Evolutionary Computing.
- Author
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Heller, Mario, Edelmann-Nusser, Juergen, Clement, Steffen, Vajna, Sándor, and Jordan, André
- Abstract
In the Olympic competitions the so-called recurve bows are used in archery. Typical characteristics of a good bow riser are little weight and high stiffness. Hence a trend in the design of risers is to reduce weight without loosing other properties. The aim of this study was to design a riser with a considerably reduced weight at a quite similar stiffness compared to the lightest riser (1114g) that is used by archers of the German National Archery Team. A parametric CAD model of the riser was designed and optimized using evolutionary computing. Best model was selected out of 1650, and a riser was manufactured with a forged aluminum alloy (AS 28) using a CNC milling machine. A test of the riser in practice by archers of the German National Archery Team succeeded: the riser is not only very stiff and light (871g) but also damps the vibrations after the shot very well. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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225. Influence of Ski Bending Stiffness on the Turning Radius of Alpine Skis at Different Edging Angles and Velocities.
- Author
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Heinrich, Dieter, Mössner, Martin, Kaps, Peter, Schretter, Herwig, and Nachbauer, Werner
- Abstract
Carved turns with Alpine Skis were investigated using a computer simulation model. Varied input data to the model were the bending stiffness of the skis, the edging angle, and the velocity. Results include the turn radius and the force distribution along the running surface of the skis. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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226. Approach of a Model for the Interaction Between Athlete, Sports Equipment and Environment.
- Author
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Krueger, Andreas, Witte, Kerstin, and Edelmann-Nusser, Juergen
- Abstract
For the interaction between athlete, sports equipment and environment there are general characteristics which are important to consider during the product design process of performance oriented sports equipment. The aim of this study is to describe these aspects of the athlete-sports equipment-system and to get a model for the interaction between athlete, equipment and environment. The model comprises the athlete himself, his activities, the sports equipment and environment. Furthermore the subjective criteria in the model, perception, emotion, status symbol and trend-setting, are of interest. Some examples will illustrate the model. This approach can be used to assist the designer of performance oriented sports equipment and thus to support a systematic product design process in sports. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
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227. Dynamic Eccentric-Concentric Strength Training of the Finger Flexors to Improve Rock Climbing Performance.
- Author
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Schweizer, Andreas and Schneider, Alexander
- Abstract
The purpose of this study was to investigate whether an additional dynamic eccentric-concentric strength training of the finger flexors may improve the performance of rock climbers. A device was developed and constructed to train the finger flexors in a dynamic eccentric and concentric fashion and was distributed along with a specific exercise plan to rock climbers. Forty five male and I female rock climbers participated in the retrospective study and answered a questionnaire concerning their training time, climbing performance (grade) and subjective strength increase. The duration of the training averaged 19 months (SD 16, range 1–60) with 40 minutes per week (SD 38, range 5–210) and constituted 15% of the whole training (range 5–100). The difficulty of climbing redpoint style (known route) improved significantly on average from 12.1 to 14.4 (numeric scale of increasing difficulty 1–24, in relation to the French scale grade 3–9a), on sight style (unknown route) from 9.5 to 11.4 and boulder (short routes) from 8.7 to 11.8. In comparison, improvement of climbing performance during the 12 months before the start of the dynamic training was significantly less averaging redpoint 11.6 to 12.1, on sight 9.3 to 9.5 and boulder 7.9 to 8.7. Increase of maximal strength was subjectively rated to be 21%, increase of endurance strength 20% and improvement of over all climbing performance 15%. Dynamic eccentric – concentric strength training of the finger flexors in rock climbers may improve strength, endurance and climbing performance (grade of difficulty) and may be of value in addition to the static strength training. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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228. Prediction of the Flexural Modulus of Fibre Reinforced Thermoplastics for use as Kayak Paddle Blades.
- Author
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Ewart, Paul. D. and Verbeek, C. J. R.
- Abstract
It can be shown that there is a strong link between paddler performance and paddle stiffness. Despite the fact that composite materials are often chosen to enable design of more rigid sporting equipment, readily available flexural modulus values for composites other than proprietary blends are not easily obtained. Therefore, when composition deviates from proprietary blends, accurate prediction of material properties becomes necessary. A mathematical model for predicting the flexural modulus of short fibre reinforced composite materials is developed based on the application of simple beam theory. The flexural modulus can be modelled by considering a small section of the composite comprising a finite number of polymer and reinforcement layers. Simple beam theory assumes that there is perfect bonding between these layers, but it is well known that interfacial adhesion plays a significant role in composite properties. To account for the interfacial layer and interfacial bonding the second moment of area of the composite beam element was modified by assuming that the contribution to the second moment of area from the matrix layer is reduced by an amount representing the nonbonded interfacial layer. The flexural modulus values obtained from the model are compared to experimental values for glass-fibre reinforced linear low density polyethylene. It has been found that the use of non-contact regions in the model resulted in improved accuracy over the model with perfect bonding for short fibre reinforced LLDPE. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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229. Development of a New Nordic Walking Equipment and a New Sporting Technique.
- Author
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Sabo, Anton, Reichel, Martin, Eckelt, Markus, and Kogler, Hannes
- Abstract
As a consequence of our intensive Nordic Walking research from the last three years, it was found out that the use of special shoes is essential. The pole length, pole construction and the construction of the handle have a biomechanical influence. Furthermore there should be a difference in Nordic Walking techniques. There is one fundamental technique from Finland, which is more or less a sporting one. But in Austria Nordic Walking is a health-movement and so we have developed, with the knowledge of the physio-therapeutics, a new, matching technique, which also requires new equipment (handle, strap…). Our last research covered the influence of Nordic Walking on the prevention of muscular tensions in the upper range of the back (M. Trapezius…). The subjects had an office job and had to work almost all day long in a sitting position in front of a computer. The subject΄s muscular activity was measured with EMG before and after a training cycle, in which they went Nordic Walking with the finish technique. The results have shown that the subjects trained muscles which are parts of the flexorloop. The muscular tensions became lower but they did not disappear. So a new Nordic Walking technique was developed. Thsi new technique trains the muscles of the extensorloop, which is not possible with conventional Nordic Walking equipment, in particular with the conventional handle and strap. Therefore we developed a new ˵strap system″. This ˵strap system″ does not only differ from the conventional handles and straps in form and look, there is also a difference in the transmission of force and the performance of the technique. With that new ˵strap system″ and the new technique it is possible to train the muscles of the extensorloop effectively, which results in a prevention of muscular tensions in the upper range of the back and a prevention of muscular dysbalances. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
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230. Safe Use and Redesign of Hydrostatic Weighing Equipment.
- Author
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Franklin, Kathryn, Williams, Simon, and Gordon, Rae
- Abstract
The aim of this study was to examine critically the safe usage of equipment used for research tests on athletes and to propose improvements. The equipment examined in this study is a bought-in hydrostatic weighing unit which is used in a research environment. Hydrodensitometry is a technique which is widely used to assess body composition. It uses Archimedes Principle to calculate the body density of a subject and this gives a measure of body fat levels. Levels of body fat and muscle are used to assess body composition to optimize muscle mass and as a performance indicator within professional sport environments. Body fat levels are used as training guidance in many sports and optimal limits are set for different sporting applications. The safety of subjects while undergoing testing is paramount. The responsibilities of testers to their subjects, as well as to themselves and their co-workers, has grown in importance from both an ethical and safety stance. With a general increasing consciousness of safety, the user needs to be aware of their legal duties but also all testers have a moral obligation to their subjects to keep them safe from harm. This coupled with the increasing numbers of personal injury claims means that the researcher is required to demonstrate a reasonable level of care for the subject΄s health and safety. Awareness of health and safety is an absolute requirement. The hydrostatic weighing equipment was examined in line with relevant European based legislation and safety requirements and these are discussed along with good practice for international testers. A full equipment and task risk assessment was carried out and hazards were identified. The main hazards found were slips and falls, exposure to chemicals, drowning and electrocution. The outcome from this study was in the short term, safe working procedures were needed with safety controls. These included a winch to remove subjects in an emergency, movement of an electronic display, chemical usage assessment and guidelines. In the long term, redesign of the equipment was necessary as, the hazards and risks were found to be significant. The redesigned equipment changed the orientation of the subject from vertical to horizontal position. The elements that were addressed were the access method into the hydrostatic system became less hazardous and adding a mechanism, which removes subjects from the water should they encounter difficulties during the testing. The redesign should also improve the accuracy and repeatability of the readings. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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231. Optimum Design and Validation of a Graphite Golf Shaft Based on Dynamics of Swing.
- Author
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Lee, Manryung and Kim, Cheol
- Abstract
A player΄s swing motion is analyzed and the head speed is assumed as a cubic function. Then, swing accelerations and forces acting on a sweet spot of a club head are calculated. Under these forces, the deflections and twists of a shaft with optimum stacking sequences are analyzed right before the impact and at the instant of impact. An efficient optimization algorithm is introduced to optimize the stacking sequence of the shaft and wall thickness that satisfy the strength, weight, flex ratings, a kick point and dynamic torsional flexion using a genetic algorithm and finite element analyses. Unlike steel, the shaft made of graphite/epoxy materials shows many different static and dynamic behaviors during swing, depending on its ply orientations. The cost function is a minimum twist of a composite club shaft and seeks the stacking sequence satisfying flex, kick point and weight requirements. After iterative 28 generations, the optimal stacking sequence for the minimum angle of twist is obtained as [30/45/–30/0/–45]
s and results in the twisting angle of 1.1°. Before the impact, the maximum deflection is 22.6 mm and the largest twist is 0.121°. At the impact, the maximum deflection is −168.991 mm and the largest twist is 0.217°. [ABSTRACT FROM AUTHOR]- Published
- 2006
- Full Text
- View/download PDF
232. Factors Determining Backspin from Golf Wedges.
- Author
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Cornish, James, Monk, Stuart, Otto, Steve, and Strangwood, Martin
- Abstract
Impact studies under dry conditions have been carried out for a range of golf balls (multi-piece solid construction balls representing a variety of compression ratings with both polyurethane (PU) and ionomer covers) using a gas cannon. The balls have been fired, at a speed of 30 m/s, at grooved and un-grooved plates at effective lofts between 20 and 70° with surface roughness, R
a =1 μm. The ball speed, launch angle and backspin magnitude post-mpact were measured using a stereoscopic launch monitor system. Analysis of backspin was successfully carried out using effective coefficient of friction and spin ratio measures. Within the range of lofts investigated the backspin rate for each of the balls showed a maximum, which was dependent on the ball type and presence of grooves. This behaviour has been rationalised as the deformation of the cover into surface features (particularly grooves at higher loft angles) leading to a higher effective friction coefficient and greater rolling. The behaviour of two-piece balls is largely characterised by the cover hardness, but the mantle needs to be incorporated for three-piece balls. [ABSTRACT FROM AUTHOR]- Published
- 2006
- Full Text
- View/download PDF
233. Modelling Traction of Studded Footwear on Sports Surfaces using Neural Networks.
- Author
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Kirk, Bob, Carré, Matt, Haake, Stephen, and Manson, Graeme
- Abstract
Traditional regression techniques have shown limited use in the development of empirical models for the traction performance quantities of studded footwear on surfaces. This is due to the unknown and often non-linear relationships between performance parameters, such as traction force, and input variables, from the shoe and surface. Experimental data has been used to train artificial neural networks to model the relationship between stud parameters, namely cross-sectional area, length and two shape coefficients, with dynamic traction as the output variable. A variety of neural network structures and optimisation algorithms were evaluated. The most promising network gave an average prediction error of 10%, compared to an error of 36% when an optimised linear model is employed. This study shows that the neural network technique has powerful potential in understanding the effect of shoe and surface parameters and in the optimisation of traction forces experienced by athletes. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
234. The use of Stereoscopy and High-Speed Video for the Measurement of Quasi-Static and Dynamic Shoe Loading Scenarios.
- Author
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Gibbs, Paul J., Mitchell, Sean R., and Harland, Andy R.
- Abstract
The need for efficient and cost effective methods of recording the structural response of running shoes under simple mechanical testing was identified in order to allow virtual prototyping. Digital video was chosen over other methods due to its availability and relatively low cost. Two complementary experiments were set up to test the performance of the data collection methods: (1) Quasi-static, uni-axial loading was applied up to 1.5 kN (+/−1N) over a period of 30 seconds and the 3D structural response recorded using two 50 Hz video cameras, (2) Dynamic, uni-axial loading to 1.5 kN (+/−200N) was performed using a drop-test rig. Shoe deformation was recorded using a high-speed video system operating at 4 kHz. Testing was performed on two shoe types with no uppers, one with a foam midsole, one with a TPU structure midsole. Analysis of the video data was done using ImageJ in conjunction with Visual Basic routines. Results showed a resolution of 0.68 mm for the quasi-static tests (in the plane of the camera) and 0.46 mm for the dynamic testing. These results were acceptable for use, although the resolution of depth using the two 50 Hz camera was only 6.81 mm, so use of another 3D method is recommended. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
235. Benchmarking Stiffness of Current Sprint Spikes and Concept Selective Laser Sintered Nylon Outsoles.
- Author
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Toon, Daniel, Kamperman, Nico, Ajoku, Uzoma, Hopkinson, Neil, and Caine, Mike
- Abstract
Stefanyshyn and Fusco (2004) demonstrated that sprint performance can be improved if the stiffness of standard running spikes is increased. The authors concluded that in order to maximise performance individual tuning of the athlete΄s shoe stiffness to the athlete΄s particular characteristics is required. Rapid manufacturing processes, such as selective laser sintering (SLS) of nylon, offer numerous advantages over conventional manufacturing techniques. Key advantages include the ability to produce complex geometries and internal structures in a single process. Of particular relevance to sprint shoe design is the ability to produce customised outsoles that are specific to the requirements of individual athletes. Sprint spike mechanical performance values were measured using a standard test and the data obtained used to produce benchmark values. The results were catalogued into an incremented range of outsole stiffness responses. Additionally, a range of SLS outsoles were subjected to the same benchmarking procedure, their performance is compared to that of commercially available spikes. The future potential to maximise sprint performance by tuning shoe stiffness to the individual characteristics of an athlete is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
236. Virtual Networks in the Tourism Industry.
- Author
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Petti, Claudio and Ndou, Valentina
- Abstract
The application of Internet technologies to tourism activities has led to the emergence of virtual networks in the tourism industry. This trend is particularly evident at the destination level. where the proliferation of destination management systems has produced substantial improvements in time, costs, quality, and flexibility of destinations' supply. However, despite these significant progresses there still appear to be some limitations, which raise the question of whether, and to which extent, the emerging virtual tourism networks are leveraging the full potentialities of Internet technologies. To try to answer this question, the results of an empirical analysis of thirty destinations web sites is presented. [ABSTRACT FROM AUTHOR]
- Published
- 2004
237. Privacy and the Online Travel Customer: An Analysis of Privacy Policy Content, Use and Compliance by Online Travel Agencies.
- Author
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O'Connor, Peter
- Abstract
Privacy concerns are threatening the growth of e-commerce. Online travel agencies have the potential to collect significant amounts of personal data as part of their normal operations and thus are at the forefront of such concerns. This study examines the quality of, and compliance with, the privacy policies of the largest online travel agencies operating internationally. While all post a privacy statement of some kind, in many cases the content of such policies is lacking and fails to comply with internationally recognised fair information practices. Transgressions most often occurred in terms of Onward Transfer, Integrity and Enforcement, indicating an unsophisticated approach to the management of personal information by the online agencies. [ABSTRACT FROM AUTHOR]
- Published
- 2004
238. Accessibility of Tourism Web Sites Within The European Union.
- Author
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Oertel, Britta, Haβe, Clemens, Scheermesser, Mandy, Sie Liong Thio, and Feil, Thomas
- Abstract
An accessible Web site is one that can be accessed in a variety of ways and does not rely on a single sense or ability of the user. Regardless of any visual, audio or physical-mental impairment users should be able to access Web sites, particularly from the public sector. This is among others an objective of the European Union. Within the framework of an analysis done in the summer of 2003, the accessibility of the tourism web offers of the National DMOs within the European Union were evaluated. The research was based on the 14 guidelines of the Web Accessibility Initiative. The evaluation took place by means of a criteria catalogue reflecting the users' point of view. The results demonstrated a bandwidth regarding the implementation of accessibility. On the one hand specific guidelines were more successfully implemented than other parameters. On the other hand there were significant differences in the overall evaluation of the National European DMOs Web sites. [ABSTRACT FROM AUTHOR]
- Published
- 2004
239. Knowledge based Destination Management Systems.
- Author
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Belbaly, Nassim, Passiante, Giuseppina, and Benbya, Hind
- Abstract
In the emerging new economy, tourism firms are trying to adapt to situations of rapid and unpredictable change. This continuous mutation of the tourism market has drawn the conceptualization of new types of Destination Management Systems (DMS) based not anymore on business models but on e-business models. Today, even if tourism firms adopt a network integrative perspective, the biggest challenge remains in their ability to manage effectively the knowledge detained in their information systems. This research develops a framework named Knowledge based Destination Management Systems which aims at overcoming actual shortcomings in DMS system design, and this through integrating the different components of DMS e-Business model with Knowledge Management systems. [ABSTRACT FROM AUTHOR]
- Published
- 2004
240. NADIM-Travel: A Multiagent Platform for Travel Services Aggregation.
- Author
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Ben-Ameur, Houssein, Bédard, François, Vaucher, Stéphane, Kropf, Peter, Chaib-draa, Brahim, and Gérin-Lajoie, Robert
- Abstract
With the Internet as a growing channel for travel services distribution, sophisticated travel services aggregators are increasingly in demand. A travel services aggregation platform should be able to manage the heterogeneous characteristics of the many existing travel services. It should also be as scalable, robust, and flexible as possible. Using multiagent technology, we designed and implemented a multiagent platform for travel services aggregation called NADIM-Travel. In this platform, a planner-coordinator agent manages users' requests as well as the response aggregation process. Service agents, on their part, act as gateways to external service providers, and are utilized to retrieve the responses. [ABSTRACT FROM AUTHOR]
- Published
- 2004
241. Critical Theory -- An Alternative Solution to IT Planning Implementation Problems in Tourism.
- Author
-
Alford, Philip
- Abstract
Empirical evidence is presented, which suggests that current approaches to IT in tourism are dominated by the assumptions of the Postpositivist paradigm and are failing to meet the objectives they have set for themselves. A theoretical critique of three cases is undertaken highlighting the IT planning implementation problems in tourism. Critical Theory is presented as an alternative to Postpositivism and, in order to address current problems, an evaluative framework is proposed based on Habermas's Theory Of Communicative Action and his theory of System and Lifeworld. The framework is tested in the context of current issues involving the distribution of packaged leisure travel in the UK. Initial findings indicate the need for the UK holiday industry to engage in further communicative action in order to develop a system of online, real time distribution, which can enable its members to meet the changing needs of the consumer, A tentative schema is presented for facilitating this communication. [ABSTRACT FROM AUTHOR]
- Published
- 2004
242. The Impact of Users' Cultural Characteristics on E-Service Quality: Implications for Globalising Tourism and Hospitality Websites.
- Author
-
Sigala, Marianna and Sakellaridis, Odysseas
- Abstract
Although e-service quality (e-SQ) is vital for online purchase and loyalty and the Internet is globalising services, limited knowledge exists on the cultural impact on e-SQ. In tourism, this is crucial as websites target multicultural users and firms are trying to develop localised webstores. This study addresses this gap by examining the link between cultural dimensions of website users and their e-SQ expectations. Based on an extensive literature review, research hypotheses are formulated and tested by gathering data from a multi-national student body. Findings provide useful implications for users segmentation and website globalisation. [ABSTRACT FROM AUTHOR]
- Published
- 2004
243. Leveraging the Capacity of the Personal Digital Assistant in the Emerging Age of Ambient Intelligence: The Rent a Mobile Guide Case.
- Author
-
Loonstra, P. B. M., Van Wijk, G., and Go, F. M.
- Abstract
In the emerging age of Ambient Intelligence wherein the customer will become ever more demanding, businesses must be innovative and apply advanced technologies to meet and exceed customers' expectations. The relationship between information and communication technology embedded in a global net and tourism offers an excellent basis for innovation. It served as a departure point for the development and testing of the Rent-A-Mobile Guide (RAMG), which leverages distributed capacity through the application of a personal digital assistant (PDA), enabling users to co-create the content of their personalized travel experience derived, in part, from lifestyle research and their spatial interaction with tourist destination Stakeholders. The identification of the customers' lifestyle allows the RAMG and its network stakeholders to sense and respond to individual customers' expectations and take measures that provide exclusive access to any source of information, at any place and lime, resulting in increased purchase volumes and user loyalty. [ABSTRACT FROM AUTHOR]
- Published
- 2004
244. 3D Intervisibility: The Key to Taking the Wondering out of Wandering.
- Author
-
Stuart, Neil and MacLeod, Fraser
- Abstract
The increasing choice of location-based service (LBS) solutions available to the tourist replicate the traditional map and guidebook paradigm, using a two dimensional geometric model of the landscape. We argue that this docs not reflect the instinctive ways by which most people orientate themselves to features of interest within their environs, or navigate between them. To overcome the shortcomings of existing LBS, the terraVX
(™) system uses a true three dimensional data model, allowing the delivery of information to be prioritised on the basis of whether a feature is visible rather than whether it is simply nearby. The 3-D representation within terraVX(™) can also deliver navigational guidance across open terrain irrespective of whether a network of roads or tracks exists. We discuss how the extended functionality offered by the terraVX(™) system design particularly suits the queries posed by tourists and illustrate this using a prototype database generated for visitors to a heritage tourism site. [ABSTRACT FROM AUTHOR]- Published
- 2004
245. Using Interactive Maps as Tourism Information Source: The Case of DESTOUR.
- Author
-
Tallinucci, Valeria, Zehrer, Anita, and Pechlaner, Harald
- Abstract
Tourism is increasingly applying innovative technological solutions regarding communication with tourists. A project of the Industrial Section and the Office for Industrial Innovation of South Tyrol developed a Tourist Information Technology cluster within the Cluster Alpine Network (CAN) as South Tyrolean companies still possess idle potentials which could be pooled and improved within the framework of clusters and competence centers, CAN South Tyrol is lo build an economic network which will offer small- and medium-sized companies especially in outlying areas the opportunity to co-operate with other companies in the region. One cluster was developed within the field of Information Technology and tourism: three startup enterprises specialized in destination management system (DMS), geographical information systems (GIS) and 3D/360 grade picture animation, have integrated their competencies for creating an innovative product for the tourist sector called DESTOUR. DESTOUR is an interactive information, communication and distribution system for tourist destinations based on geographical maps integrating tourist information, such as accommodations and tourist services, and online booking. [ABSTRACT FROM AUTHOR]
- Published
- 2004
246. Mobile Technologies Diffusion in Tourism: Modelling a Critical Mass of Adopters in Italy.
- Author
-
Corigliano, Magda Antonioli and Baggio, Rodolfo
- Abstract
The next generation mobile technologies have very important implications in the travel and tourism sector. Tourism presents great potential for the use of new mobile technologies and constitutes an area of ample opportunity for deploying the state-of-the-art mobile Internet technologies. A survey has been conducted on a random sample of Italian university students, one of the most important segments of cellular telephone users, in order to analyse the main determinants for the building of a critical mass of adopters of 3G mobile technologies. This critical mass is fundamental in guaranteeing a "mass" diffusion. Students' networks exhibit non-random structures, therefore the speed with which an opinion or a piece of information spreads is very high. A possible growth pattern is modelled. The largely positive attitude toward the adoption of 3G technology shown, allows the modelling of a short term build-up of a critical mass of users. [ABSTRACT FROM AUTHOR]
- Published
- 2004
247. Contents.
- Published
- 2004
248. Evaluating the Electronic Market Hypothesis in the Airline Distribution Chain.
- Author
-
Sigala, Marianna
- Abstract
The airline distribution chain is an excellent example of the impact of ICT and particularly of the Internet on industry structures and interorganisational relations. However, although the opposing effects of ICT on market structure have been summarized and tested into the Electronic Market Hypothesis (EMH), none study has examined yet the impact of Internet advances on EMH's hypotheses. By gathering data from the airline distribution chain, this study tests EMH's validity in the light of e-commerce developments. An enhanced model of EMH is proposed and implications for both researchers and professionals are provided. [ABSTRACT FROM AUTHOR]
- Published
- 2003
249. Networking for Small Island Destinations -- The Case of Elba.
- Author
-
Pechlaner, Harald, Tallinucci, Valeria, Abfalter, Dagmar, and Rienzner, Hubert
- Abstract
There is a tradition in tourism literature dealing with the problems and prospects of small and medium-sized enterprises associated with the applications of IT solutions. This article focuses on the special case of small islands in the Mediterranean, addressing the peculiar problems of seclusion and isolation. An empirical inquiry among the tourist entrepreneurs of the Isle of Elba deals with the respondents' attitude and behavior towards IT- and e-commerce solutions but also cooperation, networking and employee qualification. The results are used to develop a business model that is based on the Internet as a local network platform and capable to manage a small island tourist destination. [ABSTRACT FROM AUTHOR]
- Published
- 2003
250. A Versatile Context Management Middleware for Mobile Web-based Information Systems.
- Author
-
Hitz, Martin and Plattner, Stefan
- Abstract
A versatile middleware for the development of context sensitive Web applications is presented which is supposed to free developers from the great effort of managing several context dimensions such as location and time. The expected benefits are shorter time to market and reduced development costs. The middleware is currently employed in the course of the development of a prototypical campus information system at the University of Klagenfurt. [ABSTRACT FROM AUTHOR]
- Published
- 2003
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