Tapered measurement

Variable-Area Flow Meters. In variable-head flow meters, the pressure differential varies with flow rate across a constant restriction. In variable-area meters, the differential is maintained constant and the restriction area allowed to change in proportion to the flow rate. A variable-area meter is thus essentially a form of variable orifice. In its most common form, a variable-area meter consists of a tapered tube mounted vertically and containing a float that is free to move in the tube. When flow is introduced into the small diameter bottom end, the float rises to a point of dynamic equiHbrium at which the pressure differential across the float balances the weight of the float less its buoyancy. The shape and weight of the float, the relative diameters of tube and float, and the variation of the tube diameter with elevation all determine the performance characteristics of the meter for a specific set of fluid conditions. A ball float in a conical constant-taper glass tube is the most common design it is widely used in the measurement of low flow rates at essentially constant viscosity. The flow rate is normally deterrnined visually by float position relative to an etched scale on the side of the tube. Such a meter is simple and inexpensive but, with care in manufacture and caHbration, can provide rea dings accurate to within several percent of full-scale flow for either Hquid or gas. 

The Ravenfield model BS viscometer is a wide shear rate range iastmment with several possible measurement systems cone—plate, parallel plates, concentric cylinders, and taper plug. The last gives shear rates of up to 10 , and the cone—plate of up to 8 x lO". The viscosity range is... 

Transverse Dimensions or Fineness. Historically, the quantity used to describe the fineness or coarseness of a fiber was the diameter. Eor fibers that have irregular cross-sections or that taper along their lengths, the term diameter has no useful meaning. Eor cylindrical fibers, however, diameter is an accurate measurement of the transverse dimension. Though textile fibers can be purchased in a variety of cross-sectional shapes, diameter is stiU a useful descriptor of the transverse dimension. Eiber diameter is important in determining not only the ease with which fibers can be twisted in converting them to yams, but also fiber stiffness, ie, fabric stiffness, and, alternatively, fabric softness and drapeabiHty. 

The rate of decomposition in unmanaged landfills, as measured by gas production, reaches a peak within the first 2 years and then slowly tapers off, continuing in many cases for periods up to 25 years or more. The total volume of the gases released during anaerobic decomposition can be estimated in a number of ways. If all the organic constituents in the wastes (with the exception of plastics, rubber, and leather) are represented with a generahzed formula of the form QH O N, the total volume of gas can be estimated by using Eq. (25-27) with the assumption of completed conversion to carbon dioxide and methane. 

Damage to the labyrinth requires replacement of the expander heat barrier or compressor shaft seal. A replacement design (Figure 5-6) uses a replaceable stainless-steel labyrinth mounted on the shaft. Because the seal is not tapered, axial movement of the shaft has little or no measurable effect on seal gas flowrates. Each labyrinth has an integral oil slinger incorporated into the design. Also, each rotating... 

Patashnick, H. and F..G. Rupprecht. Conrinuoiis PMm Measurements Using Tapered Element Oscillating Microbalance. /. Air Waste Manage. Assoc. 41 (1991), pp. 1079-1083. 

Pi = liquid viscosity, centipoise Pg = gas density, lb/fF Pi = liquid density, lb/fF CT = surface tension, dynes/cm 0 = tube-taper angle (measured from horizontal), degrees... 

Shiverlanke L.C., Anderson G.P., Golden J.P., Ligler F.S., The effect of tapering the optical fiber on evanescent-wave measurements, Analytical Letters 1992 25 1183-1199. 

Center for Healthcare Technologies at Lawrence Livermore National Laboratory in Livermore, potentially capable to measure pH at or near the stroke site29. The probe is the distal end of a 125 pm fibre tapered up to a diameter of 50 pm. A fluorescent pH-indicator, seminaphthorhodamine-1-carboxylate, is embedded inside a silica sol-gel matrix which is fixed to the fibre tip. Excitation of the dye takes place at 533 nm and the emission in correspondence of the acid (580 nm) and basic (640 nm) bands are separately detected. The use of this ratiometric technique obviates worrying about source fluctuations, which have the same effects on the two detected signals. The pH sensor developed was first characterised in the laboratory, where it showed fast response time (of the order of tens of seconds) and an accuracy of 0.05 pH units, well below the limit of detection necessary for this clinical application (0.1 pH units). The pH sensor was also tested in vivo on rats, by placing the pH sensor in the brain of a Spraque-Dawley rat at a depth of approximately 5 mm30. 

Mercury porosimetry is based on the fact that mercury behaves as a nonwetting liquid toward most substances and will not penetrate the solid unless pressure is applied. To measure the porosity, the sample is sealed in a sample holder that is tapered to a calibrated stem. The sample holder and stem are then filled with mercury and subjected to increasing pressures to force the mercury into the pores of the material. The amount of mercury in the calibrated stem decreases during this step, and the change in volume is recorded. A curve of volume versus pressure represents the volume penetrated into the sample at a given pressure. The intrusion pressure is then related to the pore size using the Washburn equation... 

Clonazepam is the most extensively studied BZ for treatment of generalized SAD. It improved fear and phobic avoidance, interpersonal sensitivity, fears of negative evaluation, and disability measures. Adverse effects include sexual dysfunction, unsteadiness, dizziness, and poor concentration. Clonazepam should be tapered at a rate not to exceed 0.25 mg every 2 weeks. 

To use the OFRR as a biosensing device, the optical resonant mode is excited and the resonant frequency is measured continuously in real time. The conceptual measurement setup is illustrated in Fig. 14.3. Laser light from a distributed feedback (DFB) laser is delivered to the OFRR using fiber optic cable. One method that has been used to excite the resonant modes is to place a tapered fiber optic cable with a diameter less than 4 pm in contact with the OFRR. The evanescent field of the tapered fiber overlaps with the evanescent field outside of the capillary wall, which enables mode coupling between the two media24. 

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