Step sequence and direction detection of four square step test

Poor balance control and falls are big issues for older adults that due to aging decline have a lower postural balance and directional control in balance performance than younger age groups. The four square step test (FSST) was developed to evaluate rapid stepping that is often required when changing direction and avoiding obstacles while walking. However, previous researchers used only the total time as the assessment in the test. The aim of this letter is to objectively quantify the sequence and direction of the steps in FSST, by using two inertial sensors placed on both feet. An algorithm was developed to automatically segment the steps performed during the test, and calculate the stepping direction from the linear velocity of the foot. Experiments were conducted with 100 Japanese healthy older adults, where sensor data and video of 20 subjects were randomly subtracted for algorithm verification. The results showed that the algorithm succeeded for 71.7% trials in recognizing both the step sequence and step direction in FSST, while 90.2% of the detection failure could be excluded with an auto verification method

Hybrid dry coolers in cooling systems of high energy physics accelerators

Wet water cooling towers in high energy physics facilities are state of the art. The advantages are robustness, effectiveness and cost-effectiveness. The return water temperature is lower than the air temperature due to cooling via evaporation. The disadvantages are the high water consumption, which becomes more costly in the future and the soiling of the heat exchangers. If the water source is taken from wells then the drawdown of the ground water level has to be taken into account.DESY intends to use hybrid dry coolers for the two future projects: the XFEL linac and the PETRA 3 synchrotron light source. A hybrid dry cooler is a combination of a dry air cooler during cold and moderate seasons and additional wet cooling during the hot summer season. The cooling surface is moistening by adding water to increase the cooling capability by a factor of 250%.By this the hybrid dry cooler saves a lot of water. The water consumption can be reduced by 80% compared to a wet cooling system. This contribution presents the consumption and the requirement of the make-up water and an estimate of the behaviour of the temperature control