Papers by Keyword: Transpiration

Abstract: This paper presents partial results of measurements in the layers of roof garden in winter and summer. In winter, the roof garden acts as additional insulator for buildings, reducing energy needed to provide heating. Layer of soil on intensive vegetative roof in the winter can considerably reduce daily temperature fluctuations. On hot summer days, the roof garden can considerably reduce the heat flux through the roof. Transpiration in plants cools the surrounding air, thus lowering the temperature of the surface of the soil.

Abstract: Drought constraints and transpiration of rubber (Hevea brasiliensis) plantations under different evaporative demand regimes were assessed by the simple water balance model. A lump water model, BILJOU (BILan hydrique JOUrnalier), is the daily water balance model. This model requires daily potential evapotranspiration (ETo) and rainfall as input climatic data, also requires site and stand parameters are maximum extractable soil water and leaf area index (LAI). The study was carried out two sites; namely Songkhla and Chachoengsao province, Thailand, traditional and new plantation area, respectively. The calibration of this model was done with sap flow measurements. Soil water derived by tensiometer for Songkhla and soil sampling for Chachoengsao were used to validate the model. Under non limiting soil water and full canopy, transpiration of rubber was influenced by evaporative demand. Consistently, under limited soil water represented as threshold of relative extractable water (REW_c < 0.4), transpiration was influenced by REW. In the new plantation area; Chachoengsao, drought constraints were evident annually from the beginning of senescence until the new accomplished flushing; December to June. However, at Songkhla site, transpiration and soil water was mainly driven by evaporative demand. And the limitation of soil water represented shortly during the plateau stage of LAI.

Abstract: The objective was to study the responses in water status and transpiration regulation of rubber trees affected by the necrotic Tapping Panel Dryness (N) by comparison with healthy trees (H). The experiment was done with 5 N trees and 5 H trees of clone RRIM600 during well soil watered periods differing in evaporative demand intensity, May and August 2007. The study compared predawn leaf water potential (ψ_pd), midday leaf water potential (ψ_mid), whole tree hydraulic conductance (K), midday sapflow density (J_s) and tree transpiration (E_T) with the average girth size 51.54 cm of H tree and 52.66 cm of N tree. These variables, investigated in the high evaporative demand day (ET_O = 3.71 mm day^-1) on 23 May 2007 and low evaporative demand day (ET_O = 1.75 mm day^-1) on 22 Aug 2007, did not significantly differ between tree types. However, over a long period, in high evaporative demand, E_T tended to be higher in N trees. Expression of E_T versus ET_O confirmed different relationships between the two tree types with a higher plateau of maximum transpiration for N trees. Our results suggested that individuals with relatively poor transpiration regulation could be more sensitive to necrotic Tapping Panel Dryness syndrome.

Abstract: Modified atmosphere packaging, Transpiration, Weight loss, Apple Abstract. In the article the modified atmosphere packaging (MAP) of post-harvest apples are developed and evaluated. Firstly, the comparison package box with MAP and without package is developed and applied to make comparison experiments of post-harvest apples during storage of 30 days, 60 days and 90 days. Secondly, the influence of MAP on the transpiration of post-harvest apples is evaluated by comparison experimental studies, the respiration model and the change of water loss for post-harvest apples is analyzed. These results show that, within the initial storage of 20 days the change of water loss of apples with MAP or without package is approximate and almost linear. After 20 days of storage duration, the two cases of water loss have obvious difference, the water loss by transpiration for apples without package still shows linearity and maintain constant transpiration rate, yet the transpiration rate of apples with MAP would gradually decrease. In addition the transpiration of post-harvest apples with MAP can be effectively retarded at high relative humidity, and the post-harvest may maintain better quality and 90 days shelf life at storage condition of constant temperature 5°C and relative humidity 60%.

Abstract: Phytoremediation is the use of vegetation for in situ treatment of contaminated soils, sediments, and water. It is best applied at sites with shallow contamination of metal pollutants. The term “assisted phytoextraction” usually refers to the process of applying a chemical additive to contaminated soil in order to increase the metal uptake by crop plants. In the process of phytoremediation, applying plant growth regulator can promote phytoextraction effects. This paper reviewed the effect of the plant growth regulator for the biological growth, plant transpiration and heavy metal stress. the increase in metal accumulation in upper parts of plant could be related to both the role of PGRs in the enhancement of plant resistance to stress (as toxic metals) and the increase in transpiration rate, i.e. flux of water-soluble soil components and contaminants by the regulation of stomatal opening.

Abstract: Transpiration of plants has an important role in heavy metal absorption. When the transpiration is flourishing, plants accumulate more heavy metals, and its enrichment capability is also stronger.This article reviews the effect of the plant transpiration on hyperaccumulators of heavy metal uptake to lay a solid foundation for further research.

Abstract: Tree-root drying can reduce the water content of a soil in a significant manner and cause foundation settlement in expansive soil. Distortions of lightly loaded structures caused by tree root absorption are often observed in areas of expansive soil. Interest in numerical modeling of the influence of trees on soil shrinkage settlements has intensified recently. Nevertheless, no prescriptive method is given to describe the parameters and conditions in a tree-root-soil-water interaction model. In this paper, a general description of the factors involved in a tree root-absorption model is discussed. The estimation of transpiration, rainfall, evaporation and root distribution is provided. Flow equation and constitutive equation are also explored to describe the soil water interactions.

Abstract: Ablatives are heat-shielding materials used to protect aerospace substructures. These materials are sacrificial in nature and provide protection primarily through the large endothermic transformation during exposure to hyper thermal environment such as encountered in re-entry modules. The performance of certain ablatives was reported in terms of their TGA/DTA in Advanced Materials-97 (pp57-65) (1). The focus of this earlier research resided in the consolidation of interface between the refractory inclusion and the host polymeric matrix to improve thermal resistance. In the present work we explore the scope of transpiration cooling in ablative performance through flash evaporation of liquid incorporated in the host EPDM (Ethylene Propylene Diene Monomer) matrix. The compression-molded specimens were exposed separately to plasma flame (15000 C) and oxyacetylene torch (3000 C) and the back face transient temperature is recorded in situ employing a thermocouple/data logger system. Both head on impingement (HOI) and parallel flow (PF) through a central cavity in the ablator were used. It is observed that transpiration cooling is effective and yields (a) rapid thermal equilibrium in the specimen, (b) lower back face temperature and (c) lower ablation rate, compared to conventional ablatives. SEM/EDS analysis is presented to amplify the point.

Abstract: A novel composite, 3D C/SiC-Cu, which contained copper as transpiration agent, was designed and prepared. The influence of copper contents (2.18, 4.86, 6.53vol %) upon the mechanical and anti-ablative properties was investigated. The flexural strengths of three composites were over 450MPa, and fracture toughness over 15.0MPa•m1/2. After being ablated for 35 seconds in flowing oxyacetylene torch environment, the composites remained integral, and the flexural strength and strength retention ratio of the composite increased with the copper content increase. The maximum recession rate of the samples in oxyacetylene torch test was as low as 0.0490mm/s.