Archaeological and Historical Investigations in Bastrop and Lee Counties, Texas

This reconnaissance-level cultural resources survey of 1900 acres in northern Bastrop County, including a small area in Lee County, Texas, was accomplished by the Center for Archaeological Research, The University of Texas at San Antonio, in July 1980. City Public Service (CPS) of San Antonio has proposed a lignite mining project in the area, and this represents the first attempt to determine the nature of the cultural resources and the problems they might present in developing the lignite deposits. Prehistoric resources in the primary area were scarce and of limited significance, but three sites on the west side of the area are considered to be of high potential and may fall within the CPS area of interest. Four historic sites were recorded, eventually, and specific recommendations were made for each. Recommendations were made for future investigations in the area. Where possible, comparisons are made between the present survey and an intensive study, conducted by the Texas Archeological Survey, of the nearby Camp Swift area

A Single-Product Inventory Model for Multiple Demand Classes

We consider a single-product inventory system that serves multiple demand classes, which differ in their shortage costs or service level requirements. We assume a critical-level control policy, and show the equivalence between this inventory system and a serial inventory system. Based on this equivalence, we develop a model for cost evaluation and optimization, under the assumptions of Poisson demand, deterministic replenishment lead-time, and a continuous-review (Q, R) policy with rationing. We propose a computationally-efficient heuristic and develop a bound on its performance. We provide a numerical experiment to show the effectiveness of the heuristic and the value from a rationing policy. Finally, we describe how to extend the model to permit service times, and to embed within a multi-echelon setting

ASPECTS OF A THREE DIMENSIONAL MOTION ANALYSIS OF THE VOLLEYBALL SPIKE IN HIGH LEVEL COMPETITION

The purpose of the study was a three dimensional motion analysis of the volleyball spike from position four during competition. Spikes were analysed at a tournament of the European league. Regarding the jump technique, only few athletes performed the discussed coordination pattern of the impulses within the body. It may be concluded that there exists reserves within the training process concerning the coordination in the takeoff phase even in high level athletes

ESTIMATION OF THE MOVING JOINT AXIS IN THE KNEE JOINT BY MOTION ANALYSIS DATA

It is essential to use individually parameterized models for the knee joint as well as for the patellofemoral joint while analyzing the correlations between external and internal loads and the efficiency of specific training exercises for the lower extremities. A new approach to estimate the moving joint axis within the knee joint using motion analysis data was evaluated. The results of this single case study show that this approach might offer a possibility to parameterize an individualized knee joint model without using MRI scans

BODY ANGLES IN VOLLEYBALL SPIKE INVESTIGATED BY MODELING METHODS

In order to understand how specific movements are performed, it is important to describe the specific movement under consideration with high accuracy. Assets and drawbacks of these movements can only be understood, if it is possible to describe movements with close-toreality and artifact-poor time histories for the inner co-ordinates. By modelling it is possible to gain further information about movement. For example it is possible to forecast effects of changes in coordination techniques. Another advantage is the quantification of motion details using inverse kinematics. Therefore, joint angles can be analyzed more accurately in a competition setting without using marker sets. The aim of this study was to perform inverse kinematics for a volleyball spike under competitive conditions and to investigate the shoulder angles by modelling methods

ACCURACY OF CALCULATED KNEE JOINT MOVEMENTS DEPENDING ON MARKER SETS AND LEG POSITION

This study investigated the influence of different marker sets and different leg positions on time histories of skeletal kinematics of the lower limb. Surface markers were attached to the thigh and the shank to reproduce their kinematics during a knee movement cycle. Certain selections of posture and marker sets minimised the expected measurement errors without further optimisation procedures. However, the results showed an approximation to skeletal movement, only. The results lead to recommendations for the use of skin based marker systems

INVESTIGATION OF SHOULDER KINEMATICS IN VOLLEYBALL SPIKES

This study investigated the shoulder kinematics of volleyball spikes, performed during European League Games. For the kinematic description of the shoulder movement quaternions and the axis-angle approach was used to avoid the gimbal lock. The orientation of the resulting axis of rotation in the shoulder joint and the rotational angle were calculated. Additionally, the 3D coordinates of the elbow movement around the shoulder and the internal and external rotation were investigated. The results show that specific movement strategies for the humerus could be detected using these methods. Interdependencies of internal and external rotation with abduction and adduction were found for shoulder movements during volleyball spikes

ANALYSIS OF SKELETAL MOTION KINEMATICS FOR A KNEE MOVEMENT CYCLE

This study estimated the skeletal motion for a knee motion cycle. The surface markers on the thigh and the shank showed the computed displacement during in vivo motion analysis. This error was minimized using optimization procedure. The displacement was generally greater on the thigh than the shank. The minimization of error produced by this procedure was more successful on the thigh than the shank. The purpose of this study was to require high value motion data. These results provide the basis to calculate the instantaneous knee axis of rotation in a follow up stud

LOWERING VELOCITY OF THE CENTRE OF MASS DURING THE APPROACH AFFECTS JUMP HEIGHT IN VOLLEYBALL SPIKE JUMPS

It is assumed that a high impact height and therefore a high jump height is a relevant factor for success in volleyball spikes. The purpose of the study was to investigate whether the speed of the vertical movement of the centre of mass during the approach phase affects the jump height or not. Therefore, spikes from position IV were analysed at a tournament of the European League. Results showed that the faster the COM can be lowered and the faster the direction of the COM movement can be turned into an upward movement, the higher the jump height can be. This should be addressed within the training process