Hand Absorption Research Articles

Graphene characterization based nano dipole antennas design for nano network wireless communication applications

Graphene-enabled nano antennas constitute a novel paradigm which is a current trend of research among designers. Graphene-based nano-antennas with nanometer in size have shown to radiate electromagnetic waves at the terahertz (THz) frequency band. Proposed research activity is an attempt of Terahertz Nano dipole antenna design through the Finite Difference Time Domain (FDTD) based numerical simulation software, i.e. CST. Graphene material as adipole antenna has been explored to get a radiation performance. Before hand absorption, reflection and transmission characteristics of the grapheme layer has been explored. Designed antenna is analyzed in terms of the reflection coefficient, and radiation pattern etc. An attempt has been done for resonance study of graphene based nano dipole antennas, in that patch antenna length parameteris changed and performance is observed. The impact of most crucial parameter, i.e., chemical potential on the grapheme radiation performance has been analyzed in terms of reflection coefficient. Proposed antenna may be suitable for wireless nano communication applications.

Temperature Increase in Human Heads Due to Different Models of Cellular Phones

The temperature increase in a realistic human head model exposed to five different cellular phone models is investigated by a bioheat equation and the finite-difference time-domain (FDTD) method at 900 and 1800 MHz, respectively. These five cellular phone models are greatly differ from each other in structure. The realistic human head model is used to investigate the temperature increase in the head affected by varying factors including; electric properties of human head tissues, hand absorption power effect, cellular phone models, homogeneous and inhomogeneous head models, cellular phone material, and the distance between the cellular phone and the head. Computed results show that the temperature increase in the head reaches the steady-state value for exposure time of about 20 minutes. For worst-case, the maximum temperature increase in the head is found to be 0.19° C at 900 MHz and 0.055° C at 1800 MHz for the inhomogeneous human head with six tissues exposed to a metallic handset held by a hand, with antenna output power of 0.6 W and 0.125 W, respectively. The maximum temperature increase in the head is far less than the threshold temperature increase of 4.5° C which can cause neuron damage.

Portable equipment for field measurement of the hand's absorption of vibration energy

Risk assessments for hand-transmitted vibration, according to international Standard ISO 5349, are based solely on the acceleration level measured directly on the vibrating surface. An alternative method could be to measure the quantity of vibration transmitted to and absorbed by the operator. These types of measurements have until now only been possible to conduct in laboratory environments using specially-designed handles. The aim of the present project has therefore been to develop portable equipment for field measurements of the hand's absorption of vibration energy. The developed equipment consists of a hand-held adapter placed in the contact area between the hand and the vibrating surface. The adapter is equipped with transducers for measurement of vibration and dynamic forces. For the force measurements, four different technical solutions were tested. An adapter, equipped with a triaxial piezo-electric force transducer as well as piezo-electric accelerometers, was found to be the most suitable solution for field measurements. The adapter is small, has a low weight and can be used for measurement on tools with different handle designs. The adapter has been tested by laboratory measurements and reliable and accurate measurement results were obtained within the frequency range of 3 to 1900 Hz, for all the three orthogonal directions in accordance with ISO 5349.