Section 4 Dimensioning

NOTE Maximum weigFt, 1 metric ton (2205 IL) cross-section dimensions, 890 by 890 mm (35 by 35 in) tare weight, 3 kg (7 lb) material of construction, woven polypropylene body and polyester lifting straps. 

Example 2.10 The polypropylene snap fit shown in Fig. 2.22 is to have a length of 10-30 mm. If the insertion force is not to exceed 4 N and the yield stress of the plastic is 30 MN/m, calculate suitable cross-sectional dimensions for the snap fit. The short-term modulus of the polypropylene is 900 MN/m and the coefficient of friction is 0.3. The safety factor on stress is to be 2. 

The exit region of a die used to extrude a plastic section is 10 mm long and has the cross-sectional dimensions shown below. If the channel is being extruded at the rate of 3 m/min calculate the power absorbed in the die exit and the melt temperature rise in the die. Flow curves for the polymer melt are given in Fig. 5.3. The product pCp for the melt is 3.3 x 10. ... 

The stresses in some folded structures can be determined with acceptable accuracy by applying elementary beam theory to the overall cross-sections of the plate assemblies. When assemblies are plates whose lengths are large relative to their cross-sectional dimensions (thin-wall beam sections, ribbed panels, and so on) and are in large plates... 

Blind holes in molded plastics are created by a core supported by only one side of the mold. The length of the core and depth of the hole are limited by the ability of the core to withstand the bending forces produced by the flowing plastic without excessive deflection. For this reason, the depth of a blind hole should not exceed three times its diameter or minimum cross-sectional dimension. For small blind holes with a minimum dimension below 1/4 in., the L/D ratio should be kept to two. With through holes the cores can be longer, since the opposite side of the mold cavity supports them (3). 

In order to make the derivation completely general, the term dc is used to represent the cross-sectional dimensions of any channel. In the case of a round tube, dc equals d.)... 

Ahmad studied specimens of an Al-Li-Cu-Mg-Zr alloy designated 8090 in the form of specimens between 1 mm and 3 mm in thickness cut from an extruded bar of cross-sectional dimensions 51 mm x 25 mm. An XPS spectrum of the surface of a sample oxidized for 5 min at 530°C in air is shown in Figure 2.6. In addition to the peaks of carbon, oxygen and magnesium, there is a lithium (Li Is) peak at 56eV binding energy. 

We use profile extrusion to make continuous products that have fixed cross-sectional dimensions, such as pipes, house siding, refrigerator door gaskets, and vindshield wiper blades. During profile extrusion the molten output from an extruder is pumped to a die where it is formed to approximately the desired cross-sectional profile. As the molten polymer leaves the die, we apply the final forming step and simultaneously cool it to yield the product in its solid state. 

Glicksman and McAndrews (1985) determined the effect of bed width on the hydrodynamics of large particle bubbling beds. Sand particles with a mean diameter of 1 mm were fluidized by air at ambient conditions. The bed width ranged from 7.6 cm to 122 cm while the other cross sectional dimension remained constant at 122 cm. Most experiments were carried out with an open bed. The bubble rise velocity increased with the bed width, in the representation of bubble velocity as... 

Fig. 1.6 Illustration of a planar-stack, solid-oxide fuel cell (SOFC), where an membrane-electrode assembly (MEA) is sandwiched between an interconnect structure that forms fuel and air channels. There is homogeneous chemical reaction within the flow channels, as well as heterogeneous cehmistry at the channel walls. There are also electrochemical reactions at the electrode interfaces of the channels. A counter-flow situation is illustrated here, but co-flow and cross-flow configurations are also common. Channel cross section dimensions are typically on the order of a millimeter.

Fig. 9—Graph establishes dimensional ranges of horizontal heater-treater an example problem Diameter and coalescing section dimensions must fall outside shaded area for adequate treatment tame...

Fig. 22. Lamella cross-sectional dimension distribution curves...

The Nernst-Einstein relationship plotted in Fig. 36.1 motivated the development of DiagnoSwiss technology, namely reducing the analysis time and reaction volumes by replacing the commonly used microtitre plate wells with typical dimensions of 100 pL volume and 1 cm2 surface area by a microchannel with a volume of 60 nL and a surface area of 0.03 cm2. The microchannel is an isotropically etched microstructure (see Section 36.2) with a minimal cross-section dimension of 40 pm,... 

The refinement (2) proceeded in the same way as for the x-ray work, except that o and S q were refined as additional variables. We assumed that the scattering was kinematic. The cross sectional dimensions of the microfibrils are 200xl0C)X and our previous work on synthetic polymer single crystals showed that the kinematic approximation was adequate for such small crystallites. Intensity measurement presented considerable difficulty in that multiple film exposures could not be obtained. Sequential exposures of the same area of the specimen led to problems of beam damage, and patterns from different areas were not comparable due to differences in the preferred orientation. As a result, only the 28 strongest non-meridional intensities could be measured. These were all for reflections which could be indexed by the Meyer and Misch unit cell, and thus the two chain unit cell was used for the refinement. 

Analysis point The three-dimensional volume in space where the laser beam intersects and illuminates the sample core of the fluid stream is the analysis point. The size of this point is determined by the cross-sectional dimensions of the laser beam and the width of the stream core itself. It is within the volume of the analysis point that particles are illuminated and signals are detected. 

Novel microreactors with immobilized enzymes were fabricated using both silicon and polymer-based microfabrication techniques. The effectiveness of these reactors was examined along with their behavior over time. Urease enzyme was successfully incorporated into microchannels of a polymeric matrix of polydimethylsiloxane and through layer-bylayer self-assembly techniques onto silicon. The fabricated microchannels had cross-sectional dimensions ranging from tens to hundreds of micrometers in width and height. The experimental results for continuous-flow microreactors are reported for the conversion of urea to ammonia by urease enzyme. Urea conversions of >90% were observed. 

Extrudate swelling refers to the phenomenon observed with polymer melts and solutions that, when extruded, emerge with cross-sectional dimensions appreciably larger than those of the flow conduit. The ratio of the final jet diameter to that of the capillary D/Dq, for Newtonian fluids varies only from 1.12 at low shear rates to 0.87 at high rates. Polymer... 

As part of the effort to design, build and put into operation a laboratory model of the Sulfur Cycle, a multi-cell, bipolar electrolyzer was constructed. This electrolyzer, shown in Figure 7, contains five cells, each with cross-sectional dimensions of 12.7 by 12.7 cm. 

The function of a die is to accept and control the available melt (extrudate) from an extruder and deliver it to downstream takeoff equipment as a shaped product (profile, film, sheet, pipe, filament, etc.). Target is to minimize deviation in cross-sectional dimensions, smooth surfaces, and a uniform output by weight at the fastest possible rate. In order to do this, the extruder must deliver melted plastic to the... 

Stir the mixture with a glass rod until solution is complete, allow the solution to stand for 15 min, unless otherwise directed, and compare the color of the solution with that of the specified matching fluid in a comparison container that also is of colorless glass and has the same internal and cross-section dimensions, viewing the fluids transversely against a background of white porcelain or white glass. 

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