Pattern Dynamics of Vegetation Growth With Saturated Water Absorption

Regular pattern is a typical feature of vegetation distribution and thus it is important to study the law of vegetation evolution in the fields of desertification and environment conservation. The saturated water absorption effect between the soil water and vegetation plays an crucial role in the vegetation patterns in semi-arid regions, yet its influence on vegetation dynamics is largely ignored. In this paper, we pose a vegetation-water model with saturated water absorption effect of vegetation. Our results show that the parameter 1/P, which is conversion coefficient of water absorption, has a great impact on pattern formation of vegetation: with the increase of P, the density of vegetation decrease, and meanwhile it can induce the transition of different patterns structures. In addition, we find that the increase of appropriate precipitation can postpone the time on the phase transition of the vegetation pattern. The obtained results systematically reveal the effect of saturated water absorption on vegetation systems which well enrich the findings in vegetation dynamics and thus may provide some new insights for vegetation protection.

Water Absorption Behavior on Natural/ Synthetic Fibre Reinforced Polymer Composites

This paper deals with the effect of moisture absorption on single coconut sheath fiber and single glass fibre. Additionally, the moisture effect in fibre reinforced unsaturated polyester composites like coconut sheath (CS) and Glass mat (GM) composite. Initially, CS and GM fibre reinforced polyester composite were produced through hand layup followed by compression moulding method. CS/UPR and GM/UPR composites were made through water treatment by dipping those composites in ordinary water for various time intervals at room temperature to study the water absorption effect. At different time periods, the absorption of water showed gradual increment. The effect of water gain in percentage for CS and GM was observed. From this experiment, it is concluded that the effect of water gain in CS/UPR composite is higher than GM/UPR composite.

Water Absorption Effect on the Propagation Velocity of Normal Waves in Composite Rebars

The article proposes the use of the acoustic waveguide method with normal Pochhammer waves to estimate the water absorption of composite fiberglass rebars. The results of experimental studies on the water absorption and temperature influence on the propagation velocity of rod and torsional waves in composite rebars samples with different physical and mechanical characteristics are presented. The sensitivity of the wave velocity parameter to water absorption and temperature fluctuations is estimated. The proposed acoustic waveguide method is characterized by high accuracy, reliability and efficiency.

Carbon Nanotube Thermal Probe Using Platinum Nano Hot-Film

This paper reports on a thermal probe using a carbon nanotube (CNT) on a platinum hot-film. CNT probe is expected to breakthrough the limitations of the existing ones owing to its unique characteristics but no practical thermal device has been fabricated yet. In order to explore the mechanisms of heating and measuring the smaller region than 10nm, we applied our recently developed sensor coupled with CNT, which consists of a suspended platinum film of 40nm × 500nm × 10micrometer. The principle of this probe as heater and sensor is explained, based on one dimensional heat conduction. Fabrication process using MEMS technique is also introduced, especially for a couple of critical techniques. One is to fabricate the nano sensor on an edge of the sensor substrate. The other is to bond a CNT on the suspended hot-film sensor. A CNT thermal probe using a multi-walled CNT of 70nm diameter and ca. 10 micrometers length is successfully fabricated. Its performances are tested in vacuum environment as to eliminate the presence of in-air conduction effect and water absorption effect around the contact point, which work for heat transport dominantly in atmospheric condition and degrade the spatial resolution. Our CNT probe showed a clear and reliable signal in vacuum and its sensitivity available for nanoscale thermal sensing and heating is confirmed.

Water Absorption Effect on Syntactic Foam Thermal Insulation of a Flexible Pipe

Thermal insulation of a flexible pipe for deepwater applications is generally obtained by spiraling syntactic foam extruded tapes around the pipe core, in between two thermoplastic sheaths. As water tightness of the insulating annulus can frequently not be guaranteed, water absorption and the effect on thermal properties of insulating material have to be determined, so as to be taken into account for Overall Heat Transfer Coefficient calculation of the flexible pipe. It is required to demonstrate the overall suitability of a specific insulating material for a given application. The first part of this paper describes accelerated fresh water absorption tests and subsequent thermal conductivity measurements, conducted on polypropylene syntactic foam filled with glass micro-spheres. Based on test data in the 50°C–100°C temperature range, a prediction model has been established to calculate water absorption for service life as long as 20 years. A relationship between thermal conductivity variation and water content has been demonstrated, so that thermal conductivity of material exposed to water can be calculated versus temperature and time of exposure, for design purpose. The second part describes the full scale thermal tests that have been performed by Technip, in order to compare the measured thermal properties and heat losses of the flexible pipes in vertical or horizontal positions, with the computer calculations. Finally, based on lab test ageing and full scale tests on non aged flexible pipe, Technip is able to predict the full thermal behaviour during all the lifetime of the pipe.