A simple steady state iterative solution of Münch pressure-flow in unbranched sieve tubes containing only water and sucrose is derived. The iterative equations can be solved on a programmable desk calculator. Solutions are presented for steady state transport with specific mass transfer rates up to 1.5 x 10(-5) mole second(-1) centimeters(-2) (= 18.5 grams hour(-1) centimeters(-2)) over distanc...

It is well known that rootstocks can have an effect on the vegetative growth and development of the tree; however, there has been no clear explanation about the physiological mechanism involved in this phenomenon. Evidence indicates that the rootstock effects on tree vegetative growth may be related to hydraulic limitations of the rootstock. The objective of these experiments was to investigate...

The optimization of guide vane closing schemes (OGVCS) of pumped storage hydro units (PSHUs) is a cooperative control and optimal operation research field in renewable energy power generation technology. This paper presents an OGVCS model of PSHUs considering the rise rate of the unit rotational speed, the specific node pressure of each hydraulic unit, as well as various complicated hydraulic a...

A root pressure probe has been used to measure the root pressure (P(r)) exerted by excised main roots of young maize plants (Zea Mays L.). Defined gradients of hydrostatic and osmotic pressure could be set up between root xylem and medium to induce radial water flows across the root cylinder in both directions. The hydraulic conductivity of the root (Lp(r)) was evaluated from root pressure rela...

During carbon dioxide (CO2) injection process, overpressure within targeted reservoirs might occur because of changes in stress related to the CO2 pressure, which could lead to deformation of the surrounding rocks, including caprocks which are geological formations with low permeability overlying a CO2 storage reservoir. The understanding for impact of effective pressure (i.e., the difference b...

Rotational drilling was a revolution in drilling technology. It made the drilling process more efficient and faster and more depth of well could be achieved through rotation method. Besides all of its advantages, the rotation approach induced some problems like pipe sticking and downhole cleaning to the drilling procedure. Hole cleaning and reduction of torque and drag seems to be vital in incl...

The effects of acute changes in circulating blood volume on embryonic vascular hemodynamics were evaluated with the use of input impedance. We simultaneously measured dorsal aortic pressure with a servo-null system and flow velocity with a 20-MHz pulsed Doppler system in n = 90 stage 24 chick embryos. We withdrew or infused 1,3, or 5 microliters of blood via a second-order vitelline vein (n = 1...

The exodermis of Iris germanica roots is multiseriate. Its outermost layer matures first with typical Casparian bands and suberin lamellae. But as subsequent layers mature, the Casparian band extends into the tangential and anticlinal walls of their cells. Compared with roots in which the endodermis represents the major transport barrier, the multiseriate exodermis (MEX) was expected to reduce ...

Little is known about the hemodynamic properties of the rapidly expanding arterial bed during embryonic development. Using a servo-null pressure system and 20-MHz pulsed Doppler velocity meter, we recorded simultaneous dorsal aortic pressure and velocity waveforms. The waveforms were digitized at 3-msec intervals and subjected to Fourier analysis. We calculated hydraulic energy and the impedanc...

A linear estimator, cokriging, was applied to estimate hydraulic conductivity, using pressure head, solute concentration, and solute arrival time measurements in a hypothetical, heterogeneous vadose zone under steady state infiltrations at different degrees of saturation. Covariances and cross-covariances required by the estimator were determined by a first-order approximation in which sensitiv...