Contactless Optical System Research Articles

Experimental test on a pointed arch model monitored by contactless optical system

Experimental test on a pointed arch model monitored by contactless optical system

Experimental test on a pointed arch model monitored by contactless optical system

Experimental test on a pointed arch model monitored by contactless optical system

Contactless Thermal Diagnostics of Acoustically Levitated Biomass under Uniform High Flux Radiation

This study reports a contactless optical system developed for investigating the fast-thermal processes of biomass under high-flux radiation, particularly for understanding the synergy of renewable biomass and concentrated solar energy. A biomass tablet was successfully suspended using a home-built acoustic levitator in a well-controlled oxygen-lean atmosphere and was irradiated under uniform radiation with a high flux of approximately 1 MW/m², i.e., ∼1000 suns. The biomass temperature profile was spatio and temporally recorded using an infrared thermographic camera. Several key thermal parameters of the biomass were determined, including the time-resolved heating rate and the ignition temperature. Three different thermal processes were identified from the temperature profiles. These are an initial fast-heating process, a following slow-heating process, and a final biomass ignition depending on the flux of radiation. At high flux, these three processes are merged, and only a steep linear increase in temperature was observed. The contactless apparatus provides the high-fidelity data of the heating rates of biomass and can benefit the understanding of the fast-thermal process associated with biomass under high flux concentrated solar radiation.

Input Data Acquisition Possibilities for Numerical Simulation of Drawing Process by means of the Contact-less Optical System and Thermo-camera

Drawing process is generally influenced by many technological parameters (e.g. holding pressure, friction coefficient, etc.) and all of them should be considered for numerical simulation of such process. This paper deals with the possibilities how to determine one of the parameters that is quite difficult to be taken into account - magnitude of heat generated during forming process. In this case only heat generated by plastic deformation was determined, thus static tensile test at different loading rates was performed. Contact-less optical system ARAMIS and Thermo-camera FLIR SC660 was used to measure distribution of both plastic deformation and temperature on samples surfaces.

Mesoscale experimental procedure and finite element analysis for an indirect tensile test of asphalt concrete

This paper describes the experimental procedures used and finite element analyses performed at the mesoscale for an indirect tensile (IDT) strength test of an Asphalt Concrete-25 Marshall specimen. The mesoscale test specimen was a three-phase composite material composed of aggregate, asphalt mastic, and void. The test results demonstrate that digital image technology combined with a finite element numerical analysis model can be used to simulate the mesoscopic damage process of asphalt concrete in an IDT test. A contactless optical system with a strain measurement accuracy of 50 was used and was a suitable method for experimentally verifying the mesoscopic strain measurements. Although the optical method provided results that were always slightly higher than those of the mesoscopic finite element method (FEM) analysis, the optical microstructure test results showed reasonably good agreement with those obtained from the FEM. Both the experimental and FEM results demonstrate that the mastic binder and interface are locations of weakness during the growth and propagation of crack damage in asphalt concrete. The study results demonstrate that the visual mesoscopic FEMs used can be an effective means for further research on the strength mechanisms of asphalt concrete at the mesoscale.

Transition from Sitting to Standing after Trans-Femoral Amputation

Standing up is an important and common daily activity. It is essential for independence and a prerequisite for walking. Many elderly and many subjects with impairments have problems with transition from sitting to standing. The aim of the present study was to determine whether there was any difference between the characteristics of standing up in trans-femoral amputees and healthy subjects. Five young trans-femoral amputees and five healthy subjects were included in the study. They were asked to stand up. The body motion was recorded using an Optotrak contactless optical system. The force and moment vectors exerted on the seat were recorded by a JR3 six-axis robot wrist sensor. The force under the feet was recorded by two AMTI force plates. The trans-femoral amputees were found to stand up more slowly than the healthy subjects. The angles of the hip, knee, and ankle joints on the amputated side were different from the angles on the healthy side or in the healthy subjects. There was also a great difference in loading between the healthy and the prosthetic foot. It can be concluded that there are differences in standing up between the trans-femoral amputees and the healthy subjects. These differences may indicate a reason for problems many elderly trans-femoral amputees face when standing up.

Functional electrical stimulation and arm supported sit-to-stand transfer after paraplegia: a study of kinetic parameters.

The sit-to-stand transfer of paraplegic patients using functional electrical stimulation (FES) of the knee extensors and arm support was analyzed in the study. In a group of 8 completely paralyzed subjects who were trained FES users, kinematic and dynamic parameters were recorded during standing up trials. A contactless optical system was used to assess the human body motion. The forces acting on the human body were measured by multi-axis force transducers. On the basis of recursive Newton-Euler inverse dynamic analysis, the forces and torques acting on the body joints were calculated. The joint moments in the lower and upper extremities during the sit-to stand task are presented in this paper. The influences of the patient's strength, FES training duration, and rising strategy on the joint loading are discussed.