A spectral multi-resolution image encoding network

After a short introduction into traditional image transform coding, multirate systems and multiscale signal coding the paper focuses on the subject of image encoding by a neural network. Taking also noise into account a network model is proposed which not only learns the optimal localized basis functions for the transform but also learns to implement a whitening filter by multi-resolution encoding. A simulation showing the multi-resolution capabilitys concludes the contribution

Der slowakische Markt für Milch und Milchprodukte: vom Beginn der Transformation bis zum EU-Beitritt

Ähnlich wie in den anderen MOEL hatte auch in der Slowakei der Systemwechsel Anfang der 90er Jahre drastische Folgen für den Agrar- undb Ernährungssektor. Die Konsumenten reagierten auf die Abschaffung der Verbrauchersubventionen bei Milch und Milchprodukten mit deutlicher Einschränkung ihrer Nachfrage. Gleichzeitig schrumpfte die Milchproduktion seit Transformationsbeginn auf gegenwärtig etwa die Hälfte des Niveaus von 1989. Molke-reien wurden geschlossen bzw. mit stetig wachsenden Überkapazitäten betrieben. In den letzten Jahren vor dem EU-Beitritt waren die Aktivitäten in diesem Sektor in erster Linie auf die Anpassung an EU-Standards gerichtet. Mittlerweile ist die slowakische Milchverarbeitung überwiegend in ausländischer Hand. Der Pro-Kopf-Konsum von Milch und Milchprodukten hat sich auf einem sehr niedrigen, von Ernährungsexperten als gesundheitlich bedenklich beurteilten, Niveau eingependelt. Dieser Diskussionsbeitrag hat eine Zusammenschau von Informationen über den slowakischen Milchsektor zum Inhalt, die die ganze Kette von der Primärproduktion über Verarbeitung und Handel bis hin zum Verbrauch umfasst. Eingebettet sind diese Ausführungen in eine Darstellung der demographischen, wirtschaftlichen und marktpolitischen Rahmenbedingungen der Slowakei.Like in other CEEC, transition in the beginning of the 1990s had significant consequences for the agricultural and food sectors in Slovakia. For example, Slovakian consumers reacted to the abolition of consumer subsidies by drastically reducing their consumption of milk and milk products. Concurrently, milk production declined and now stands at fifty percent of its 1989 level. Dairies were closed down while those remaining carried on producing under constantly increasing overcapacities. In the years prior to EU accession, activities in the milk sector were primarily aimed at the adoption of EU standards. Meanwhile, the Slovakian milk processing industry is predominantly in the possession of foreign investors. Present per capita consumption of milk and milk production is still at a very low level, which nutrition experts assess as an alarming health risk. This paper contains an overview of the Slovakian dairy sector, which comprises the complete milk chain - from primary production to processing and retailing up to consumption. The description is complemented by background information on demographic, economic and political parameters in Slovakia

Der slowakische Markt für Milch und Milchprodukte: vom Beginn der Transformation bis zum EU-Beitritt

Ähnlich wie in den anderen MOEL hatte auch in der Slowakei der Systemwechsel Anfang der 90er Jahre drastische Folgen für den Agrar- undb Ernährungssektor. Die Konsumenten reagierten auf die Abschaffung der Verbrauchersubventionen bei Milch und Milchprodukten mit deutlicher Einschränkung ihrer Nachfrage. Gleichzeitig schrumpfte die Milchproduktion seit Transformationsbeginn auf gegenwärtig etwa die Hälfte des Niveaus von 1989. Molke-reien wurden geschlossen bzw. mit stetig wachsenden Überkapazitäten betrieben. In den letzten Jahren vor dem EU-Beitritt waren die Aktivitäten in diesem Sektor in erster Linie auf die Anpassung an EU-Standards gerichtet. Mittlerweile ist die slowakische Milchverarbeitung überwiegend in ausländischer Hand. Der Pro-Kopf-Konsum von Milch und Milchprodukten hat sich auf einem sehr niedrigen, von Ernährungsexperten als gesundheitlich bedenklich beurteilten, Niveau eingependelt. Dieser Diskussionsbeitrag hat eine Zusammenschau von Informationen über den slowakischen Milchsektor zum Inhalt, die die ganze Kette von der Primärproduktion über Verarbeitung und Handel bis hin zum Verbrauch umfasst. Eingebettet sind diese Ausführungen in eine Darstellung der demographischen, wirtschaftlichen und marktpolitischen Rahmenbedingungen der Slowakei. -- E N G L I S H V E R S I O N: Like in other CEEC, transition in the beginning of the 1990s had significant consequences for the agricultural and food sectors in Slovakia. For example, Slovakian consumers reacted to the abolition of consumer subsidies by drastically reducing their consumption of milk and milk products. Concurrently, milk production declined and now stands at fifty percent of its 1989 level. Dairies were closed down while those remaining carried on producing under constantly increasing overcapacities. In the years prior to EU accession, activities in the milk sector were primarily aimed at the adoption of EU standards. Meanwhile, the Slovakian milk processing industry is predominantly in the possession of foreign investors. Present per capita consumption of milk and milk production is still at a very low level, which nutrition experts assess as an alarming health risk. This paper contains an overview of the Slovakian dairy sector, which comprises the complete milk chain - from primary production to processing and retailing up to consumption. The description is complemented by background information on demographic, economic and political parameters in Slovakia.Slovakia,dairy industry,milk consumption,milk production,milk processing,structural change,Slowakei,Milchbranche,Milchkonsum,Milcherzeugung,Milchverarbeitung,Strukturwandel

KINETICS OF THE COMPUTER-SIMULATED TENNIS STROKE WITH DIFFERENT RACKETS

INTRODUCTION: The aim of this biomechanical analysis of the tennis stroke is the determination of the effects of the mass properties of different tennis rackets' on the kinetics of the striking arm. In contrast to experimental investigation the computer simulation gives an infinite temporal resolution so that the arm movements could be investigated especially during the racket-ball-contact phase. The planar model of the tennis stroke consisting of the immovable trunk, the upper arm, the lower arm, the hand and• the racket was derived from the mo ei of the human body by GLITSCH (1993). The striking arm with a racket tightly fixed to the hand was constructed as a pendulum of three rigid bodies which are connected with frictionless revolute joints. An elastic spring (0=45000 N/m) represents the ballracket-contact. The arm-racket-system• rotates around the shoulder joint and hits the resting ball in the respective" racket area centre. Considering rigid body mechanics the mass distributions of three different tennis rackets were measured and served as input for the model. The computer simulation with the initial conditions referring to real tennis strakes registered by KNUDSON (1990) was carried out with the software-packet DADS (Dynamic Analysis and Design System) by CADSI (Computer Aided Design Software Inc.). RESULTS: As it is shown in figure 1 the computer simulation has calculated an elbow flexion when rackets 1 or 2 are used. When the tennis forehand stroke is carried out with racket 3 the elbow is kept extended during the ball-racket-contact phase. The quite different arm movements during the impact with different tennis rackets are the result• of the separate locations of the centres of percussion with respect to the rigid handracket-system. The centre of percussion of racket 3 (5.3 cm) is located more distally than its centre of area because of the different mass distribution and finally because of its greater moment of inertia. In contrast to that the centre of percussion of the other two rackets (racket 1: -3.6 cm, racket 2: -3A cm) are located more proximally than the hitting point. CONCLUSION: The mechanical properties of tennis rackets, particularly the mass distribution, are responsible for different and movements during the ball-racket-contact phase. Obviously, there is no consensus of the preferable mass distribution of modern tennis rackets. This model can objectively assist in choosing one's individual favourable racket. REFERENCES: Glitsch U., Farkas R. (1993): Applications of a multi-body simulation model in human movement studies. Proc. Int. Soc. of Biomech., XIV1h congress, Paris. Knudson, DV (1990): Intrasubject variability of upper extremity angular kinematics on the tennis forehand drive. Int. J. of Sport Biomech., 6, 415-421

Use Cases and Collaboration Scenarios: how employees use socially-enabled Enterprise Collaboration Systems (ECS)

In recent years we have seen the emergence of a new type of collaboration software, the so-called “Enterprise Social Software”. The “social features” of this software type have stimulated a renewed interest in Enterprise Collaboration Systems (ECS). In this article we present findings from a longitudinal research project on the introduction and use of ECS in companies. We argue that ERP Systems and ECS are inherently different and that the process-paradigm that is common to ERP cannot be applied identically to ECS. To address this issue, we suggest the two concepts use case and collaboration scenario for the analysis and description of collaboration activity in companies. From the literature and 26 case studies we identified typical use cases and collaboration scenarios that can serve as blueprints for ECS introduction projects. The longitudinal objective of our research is to assist companies with their ECS initiatives and to provide them with a catalog of existing use cases and collaboration scenarios from various industry settings

PRESSURE DISTRIBUTION UNDER THE FOOT DURING TAKE OFF IN TRAMPOLINING

In the past, biomechanical investigations in trampolining were mostly concerned with the aerial movements, whereas the take off was rarely in the focus of interest. One reason for this lack may be the difficulties in performing dynamic measurements during the take off. The development of new pressure measurement devices encourages their use also in trampolining. At first two questions should be answered with the aid of this instrumentation. 1. Which differences in the pressure distribution occur between beginners and skilled gymnasts? 2. Are there any basic differences in the pressure distribution at take off between exercises with and without moment of impulse? Methods The pressure distribution was determined using F-SCAN, a resistive based in-shoe measurement device. The insole is 0.17 mm thick and contains 960 sensors (resolution 4 sensors/cm2). The sampling rate was 50 Ha and the sampling time embraced 4 s. The sole was cut to the necessary size and put in the right gymnast shoe of the subject. The data transmission ensued via a cuff unit (m = 300 g) and a wire to a personal computer. The investigated movements included three categories of exercises: 1. straight jump, 2. forward sommersaults (single up to double), 3. backward somersaults (single up to double). As subjects sewed 2 female beginners and 5 skilled gymnasts (female and male). Results and Discussion The ratios of support time and flight time confirm the spring characteristic of a trampoline. For one subject the support time is constant and independent from the jump hight. No general differences in the pressure distribution could be found between beginners and skilled subjects. Except the straight jump, it was not possible to distinguish the different somersaults (forward - backward) in terms of pressure distribution by the use of statistical methods. But the intraindividual analysis of the exercises showed a relation between the skill and the variance of the pressure distribution. It can be concluded that the dynamic of the foot contact has always the same characteristic. The moment of impulse is produced by the movements of the upper parts of the body

Changes in intracellular ion activities induced by adrenaline in human and rat skeletal muscle

To study the stimulating effect of adrenaline (ADR) on active Na+/K+ transport we used double-barrelled ion-sensitive micro-electrodes to measure the activities of extracellular K+ (aKe) and intracellular Na+ (aNai) in isolated preparations of rat soleus muscle, normal human intercostal muscle and one case of hyperkalemic periodic paralysis (h.p.p.). In these preparations bath-application of ADR (10−6 M) resulted in a membrane hyperpolarization and transient decreasesaKe andaNai which could be blocked by ouabain (3×10−4 M). In the h.p.p. muslce a continuous rise ofaNai induced by elevation ofaKe to 5.2 mM could be stopped by ADR. In addition, the intracellular K+ activity (aKi), the free intracellular Ca2+ concentration (pCai) and intracellular pH (pHi) were monitored in rat soleus muscle. During ADRaKi increased, pHi remained constant and intracellular Ca2+ apparently decreased. In conclusion, our data show that ADR primarily stimulates the Na+/K+ pump in mammalian skeletal muscle. This stimulating action is not impaired in the h.p.p. muscle

INFLUENCE OF RACKET LENGTH ON TENNIS STROKE

The current design of tennis rackets tends toward so-called long body rackets, expected to produce a higher rebound velocity because of the more distally situated hitting point. To study the influence of racket length on the tennis stroke, a standardized computer- model was used, as described by Detlefs and Glitsch (1996). This computer simulation allows a 100% reproducibility with an almost arbitrary time resolution and an independent variation of all input parameters. The experimentally determined geometrical mass distributions of several existing rackets served as input variables for this model. The interesting results are the rebound velocity of the ball and the joint forces of the grip, wrist and elbow. The investigation indicates that the shape of the longer rackets is either obtained by a simple elongation of the grip, keeping the design of the short version, or by creating a completely new design in regard to the mass geometry. As we can see from Fig 1, the gain from a 2% higher rebound velocity increases the loads in the wrist (16%), elbow (17%) and particularly the grip joint (212%), which results in no advantages at acceptable costs for the hobby player. On the other hand, more sophisticatedly designed long body rackets increase ball velocity without producing higher impact loads on the arm. Thus only rackets that are especially designed for a long version yield advantages in tennis performance. An increase in length alone is not a significant feature for the performance of a racket. References: Detlefs, C.; Glitsch, U. (1996). Kinetics of the computer simulated tennis stroke with different rackets. Proc. XIVth Intern. Symposium on Biomechanics in Sports, Funchal, 573-576

MODELING OF ELASTIC RACKET PROPERTIES IN THE DYNAMIC COMPUTER SIMULATION OF TENNIS

INTRODUCTION: Experimental difficulties in tennis research caused by the complexity of the stroke and the short contact phase demand the development of complex computer simulations models which can lead to a better understanding of the tennis stroke. Two different methods are currently in use: (1) The direct dynamics approach, which simulates the dynamic interaction between arm, hand, racket and ball, considering all inertial properties. (2) The finite element method, which analyses the elastic behavior of rackets under static conditions. The aim of this study was to evaluate a complex dynamic simulation model of the tennis stroke, including the elastic racket properties. Therefore a combination of both approaches was tested, by using the results of a finite element analysis as input for a flexible racket model in direct dynamics. METHODS: The racket model was an elastic beam (78 nodes) with parameters determined experimentally. For the dynamic analysis, the model was combined with a multiple rigid body pendulum simulating the players’ arm. By comparing the results of various stroke simulations with different boundary conditions and experimental data, the requirements of a flexible simulation model were worked out. The interesting parameters are acceleration and the vibration frequencies of the racket. RESULTS: First it must be stated that a complex dynamic tennis simulation including all important mechanical properties (inertial and elastic) of the racket is possible (Fig. 1). Second, the analysis of the vibrational parameters indicates that the tennis racket behaves as a freely vibrating body. Only the combination of this racket model with a suitable hand-racket-connection can simulate a real tennis stroke (Fig. 2). Thus, with the described model different previous results could be validated by computer simulation: (1) It is not necessary to fix the handle with large grip forces. (2) Racket tests with a clamped handle lead to incorrect results. CONCLUSIONS: The findings of this evaluation study confirm the possibilities of dynamic tennis simulation. Further investigations concerning the influences of racket properties (e.g., stiffness, node locations) on stroke characteristics are conceivable. [Figures