Exploring the potential high energy locations and intensities in confined work spaces of waveguide dimensions

27th International Conference on CADCAM, Robotics and Factories of the Future 2014

工业技术;机械制造

Rodriguez, Ricardo^1 ; Lewis, Winston G.^1

Department of Mechanical and Manufacturing Engineering, University of the West Indies, St. Augustine Campus, Trinidad and Tobago^1

关键词: Adverse health effects;    Confined space;    Microwave exposure;    Plane wave propagation;    Specific absorption rate;    Waveguide dimensions;    Waveguide technology;    Work environments;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/65/1/012011/pdf
DOI  :  10.1088/1757-899X/65/1/012011

学科分类：工业工程学

来源: IOP

【 摘 要 】

Adequately identifying and managing hazards at the workplace can be a tedious task which extends into the realm of uncertainty, probability and prediction models in order to fully comprehend the nature of the hazard. As such, organizations cannot be blamed for knowledge gaps in the training of personnel they contract to ensure a safe and healthy work environment, especially where there are latent hazards. Electromagnetic wave propagation at frequencies in the SAR (specific absorption rate) region is a special concern to authorities involved in setting RF (radiofrequency) and microwave exposure guidelines. Despite that there is no conclusive evidence to suggest that non-ionizing electromagnetic radiation causes adverse health effects other than thermal, no effort should be lost to ensure that workers and the public at large are adequately protected from unnecessary exposure to radiation. Standards however set exposure limits for free space, plane wave propagation but fall short in compiling information on intensities of these waves after they undergo reflection and diffraction from wall surfaces. Waveguide technology has managed to constrain microwaves to remain within set boundaries, with fixed frequencies that force the waves to behave differently to if they were moving in free space. This technology has offered the ability to transport more energy for communication purposes other than transmission lines. The size of a waveguide may be to the order of a few centimetres and can guide RF of wavelengths of the order of centimetres also but what if spaces of larger dimensions are capable of being waveguides and can guide waves of larger wavelengths such as those that correspond to frequencies between 30MHz to 300MHz? Such RF waves belong to the SAR region of the spectrum where strict exposure limits are set for health and safety protection since a standing man acts as a dipole antenna for this radiation and can absorb maximum energy from propagating RF waves. This review visits the likelihood for potential energy build-up due to RF propagation in confined spaces that are of waveguide design but with larger dimensions. Such confined spaces include silos, tanks, pipes, manholes, air-condition ducts, tunnels, wells, engine rooms and operator rooms on board vessels. In these confined spaces waves reflect off of the walls and combine constructively or destructively with incident waves producing reinforcement or cancellation respectively. Where there is reinforcement, the intensity of the wave for a particular distance in accordance with the standard, may exceed the exposure limit for this distance from the source thereby exposing the worker to larger intensities than the accepted limit and presenting a potential health and safety threat.