Stem Diameter

The diameter of the stems at the base also varies among clones and with production conditions. The initial diameter increases as the plant grows with mature stems, generally 1.6 to 2.4 cm in diameter. 

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Jibutilon theophrasti is a herbaceous annual plant produciag a jute-like fiber. The plant is native to the People s RepubHc of China and is commercially grown ia China and the former USSR. Because of its association with jute ia mixtures and export, it is also called China jute. The plant grows to a height of 3—6 m with a stem diameter of 6—16 mm. After harvesting by hand and defoHation, bundles of the stems are water retted and the fiber is extracted by methods similar to those for jute. The fiber is used for twiae and ropes. 

If the concerted four-center mechanism for formation of chloromethane and hydrogen chloride from chlorine and methane is discarded, all the remaining possibilities are stepwise reaction mechanisms. A slow stepwise reaction is dynamically analogous to the flow of sand through a succession of funnels with different stem diameters. The funnel with the smallest stem will be the most important bottleneck and, if its stem diameter is much smaller than the others, it alone will determine the flow rate. Generally, a multistep chemical reaction will have a slow rate-determining step (analogous to the funnel with the small stem) and other relatively fast steps, which may occur either before or after the slow step. 

Critical parameters concerning the skeletal stem include the stem diameter (D) the ratio of the stem diameter to the pith core diameter (D/P) the xylem thickness/pith diameter ratio (X/P) and the xylem-to-pith ratio, defined as XPR. The reason for both X/P and XPR is that X/P... 

Stem construction consists of a waxy epidermis with xylem cylinder and spongy pith with a "pinhole" tube at the center. The xylem/pith radius ratio (XPR) is about 0.46 and typical stem diameter is 0.95 cm. Typical stalk weight is 26 g, height is 130 cm, and cultivation density is 72/m2. The density of the aster woody material (xylem) was determined to be 474 kg/ m3, which is similar to that of a light hardwood (lighter than pine). 

In large thistle plants, the stem can be 3 cm in diameter. Although this stem size is admirable from the prospect of bulk, it may make cutting by conventional cutter-baler equipment difficult. The stalk consists of a large, spongy pith that does not rot or dry up for up to 1 yr. Although the stem diameter is impressive, the density of burnable mass is only moderate and the expected yield/acre is low. 

Dames Rocket dies off and dries out by early August. It is one of the earliest of the sclerified stalked plants that is ready to harvest. The plant grows to over 1 m, and the stem diameter is about 1.1 cm. The XPR for this plant is a lowly 0.22, with a correspondingly low expected yield. 

B. Suppose that there are four plants/m2 of ground and that their stem diameter is 3 cm. If the thermal conductivity coefficient of the stem is the same as that of water, and the temperature changes from that of the bulk of the vegetation to that of the ground in 0.8 m, what is the rate of heat conduction in W down each stem What is the average value of such Jh per m2 of the ground ... 

Cut height at least 50 cm (preferably 60 cm) stem diameter 10 cm, at least 13 mm above the graft union at least four feathers (>30 cm) at a height of at least 70-100 cm shallow angle... 

Flanged connections in sizes 24in. to 6ft Flanged connections in sizes above 6ft Packed valves up to in. stem diameter Packed valves above in. stem diameter Lubricated plug valves Petcocks Sight glasses... 

Treesi woody plants with a single bole, in the tropics having che first branch 10 m above the ground, and a stem diameter at bract height of at least 40 cm. 

Figure 6.4 Observed diffusivity in a canopy normalized by the mean velocity and stem diameter. Vertical bars indicate one standard deviation among cases conducted at the same canopy density ad, but different velocity, a) Red > 100. Vertical (solid) and lateral (open) diffusivity observed in the lab (triangle) and in the field (circle) from Nepf et al. [460], Tarrel [602], and Lightbody [371]. b) Red < 100, only mechanical diffusion is present closed symbol from Nepf et al. [460], open symbol from Sena et al., [570],...

Figure 6.6 Measured longitudinal dispersion normalized by velocity and stem diameter, (b) Comparison of observed (dots) and predicted (lines) dispersion for Re,/ = 100. Contribution by the recirculation zones (gray solid line), the wake shear (gray dashed line), and the gaps (black dashed line) and the total dispersion (black solid line) based on equation 6.18 with Co = 1.8, vT = 0.03 cm2s l, t = 7.5 s. These parameters were based on experimental and literature values and were not adjusted to fit the data. From White and Nepf [643]. Reprinted with permission from Cambridge University Press.

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