Wrist Prosthesis: New Two Degrees-Of-Freedom Hydraulic Wrist Mechanism for Hand Prostheses

Since there is a lack of functional active two degree of freedom wrist mechanisms for hand prostheses, one is designed in accordance to the needs of the user, such that it can be provided with hand prostheses and used by patients. A list of requirements is used to design a wrist mechanism, after which the prototype is tested to validate the design compared to the requirements. This is done with a test setup where, among others, torque and position of the mechanism are measured. A hydraulic vane cylinder is chosen as the rotation mechanism for both degrees of freedom, but only one degree of freedom is fabricated and tested as a proof of concept. The vane cylinder leaked and could not muster any significant torque. This leaking is probably caused by scratches in the surface of the cylinder wall. Other requirements could be validated despite this setback. The range of motion for instance could be achieved, only the stroke of the master cylinder had to be increased due to the compression of air. The weight, 21.2g for the fabricated working mechanism, and dimensions, 20.7mm height and 30mm diameter, of the mechanism have also been met. It can be concluded that this hydraulic vane cylinder is a promising wrist mechanism to use in hand prostheses, because it is a small and compact design, but with the recommendation to have a precise fabrication with a smooth surface finish so that the vane cylinder is not leaking.Biomedical EngineeringBioMechanical EngineeringMechanical, Maritime and Materials Engineerin

In situ high-temperature EXAFS measurements on radioactive and air-sensitive molten salt materials

The development at the Delft University of Technology (TU Delft, The Netherlands) of an experimental set-up dedicated to high-temperature in situ EXAFS measurements of radioactive, air-sensitive and corrosive fluoride salts is reported. A detailed description of the sample containment cell, of the furnace design, and of the measurement geometry allowing simultaneous transmission and fluorescence measurements is given herein. The performance of the equipment is tested with the room-temperature measurement of thorium tetrafluoride, and the Th—F and Th—Th bond distances obtained by fitting of the EXAFS data are compared with the ones extracted from a refinement of neutron diffraction data collected at the PEARL beamline at TU Delft. The adequacy of the sample confinement is checked with a mapping of the thorium concentration profile of molten salt material. Finally, a few selected salt mixtures (LiF:ThF4) = (0.9:0.1), (0.75:0.25), (0.5:0.5) and (NaF:ThF4) = (0.67:0.33), (0.5:0.5) are measured in the molten state. Qualitative trends along the series are discussed, and the experimental data for the (LiF:ThF4) = (0.5:0.5) composition are compared with the EXAFS spectrum generated from molecular dynamics simulations.RST/Reactor Physics and Nuclear MaterialsEMSD AS-south Project engineersRST/Technici PoolApplied SciencesRST/Neutron and Positron Methods in Material

The completely renewed and upgraded neutron reflectometer at the TU Delft Reactor Institute

The horizontal time-of-flight neutron reflectometer at the reactor of the Delft University of Technology, The Netherlands, has been completely renewed, relocated, and upgraded and allows for the study of air/liquid, solid/liquid, and solid/air interfaces. Innovations in the redesign include (i) a completely flexible double disk chopper system allowing to choose the optimal wavelength resolution with exchangeable neutron guide sections between the chopper disks to increase intensity, (ii) a movable second diaphragm just before the sample position to better control the beam footprint on the sample and effectively decrease counting times, and (iii) guides along the entire flight path of the neutron reflectometer. The performance of the renewed reflectometer is illustrated with measurements of hydrogen sensing materials.RID/TS/Instrumenten groepEMSD AS-south Project techniciansRID/TS/Technici PoolEMSD AS-south Project engineersRST/Technici Poo