Expansion or Contraction

A uniform spreading action is achieved only when the tow bands entering and leaving the roller are symmetrically distributed relative to the plane of the roller bow. 

To laterally contract the web, the apex of the bow is set in a direction opposite to direction of fiber movement. The web will meet on the convex side and leave from the concave side. 

---

Interactions at the molecular or ionic level cause an expansion or contraction of the solution so that, in general... 

Wangle bending s the Strain that results from the expansion or contraction of bond angles from the normal values of 109 5° for sp hybridized carbon... 

Our primary interest in the Flory-Krigbaum theory is in the conclusion that the second virial coefficient and the excluded volume depend on solvent-solute interactions and not exclusively on the size of the polymer molecule itself. It is entirely reasonable that this should be the case in light of the discussion in Sec. 1.11 on the expansion or contraction of the coil depending on the solvent. The present discussion incorporates these ideas into a consideration of solution nonideality. 

The RMS-800 provides steady-shear rotational rates from 10 to 100 rad/s and oscillatory frequencies from 10 to 100 rad/s. An autotension device compensates for expansion or contraction. With the standard 25- and 50-mm parallel plates, the viscosity range is 50-10 mPa-s, and the shear modulus range is 8 x 10 to 10 N/m. These ranges can be expanded with nonstandard plates, cones, and a Couette system. The temperature range is 20-350°C (-150 0 optional). 

Further expansion of 13-vertex species or thermal metal transfer reactions leads to the 14-vertex cluster [(T -C H )Co]2C2B2qH22 [52649-56-6] and [52649-57-7] (199). Similar 14-vertex species have been obtained from tetracarbaboranes (203) and show unusual stmctures. The isomeric bimetallic cobaltacarborane complexes /(9j (9-(Tj -CpCo)2C2BgH2Q (cp = C H ) can be formed by either polyhedral expansion or contraction reactions. Six isomers of this cluster are formed in the thermally-induced intermolecular metal transfer and polyhedral expansion of the 11-vertex f/oj o-(ri -C H )CoC2BgH Q. 

Thermal-expansion and -contraction loads occur when a piping system is prevented from free thermal expansion or contraction as a result of anchors and restraints or undergoes large, rapid temperature changes or unequal temperature distribution because of an injection of cold liquid striking the wall of a pipe cariying hot gas. 

A line configuration in a system of uniform size in which expansion or contraction must be absorbed largely in a short offset from the major portion of the run... 

Displacement Strains The concepts of strain imposed by restraint of thermal expansion or contraction and by external movement described for metallic piping apply in principle to nonmetals. Nevertheless, the assumption that stresses throughout the piping system can be predic ted from these strains because of fully elastic behavior of the piping materials is not generally valid for nonmetals. 

Figure 4 A representative step m the downhill simplex method. The original simplex, a tetrahedron in this case, is drawn with solid lines. The point with highest energy is reflected through the opposite triangular plane (shaded) to form a new simplex. The new vertex may represent symmetrical reflection, expansion, or contractions along the same direction.

The thermal expansion and contraction of solids can also have safety implications. For a given material the amount of its linear expansion, or contraction, in one direction is directly related to temperature and its original size (i.e. length, diameter, circumference). Thus ... 

Does material change phase from its state in normal operation, during the start-up, and shutdown of plant Is this acceptable, e.g. does it involve expansion or contraction, solidification, etc. ... 

Provide flexibility to allow for thermal expansion, or contraction, of pipework and connected equipment. 

It is quite common in modem engineering designs, for plastics to be used in conjunction with other materials, particularly metals. In such cases it is wise to consider the possibility of thermal stresses being set up due to the differences in the thermal expansion (or contraction) in each material. 

Expansion joint A flexible joint in a run of pipework or ductwork that allows expansion or contraction. 

When prepanng mobile phase mixtures each individual component should be measured out separately and only then placed in the mixing vessel This prevents not only contamination of the solvent stock by vapors from the already partially filled mixing vessel (e g ammonia ) but also volumetnc errors caused by volume expansions or contractions on mixing... 

In both Equations (4.100) and (4.101), the six Oj are the coefficients of thermal deformation (expansion or contraction and distortion, I.e., shear), and AT is the temperature difference. In Equation (4.101), the terms CjjCXjAT are the thermal stresses if the total strain is zero. 

The structures of chalcogen-nitrogen compounds are frequently unpredictable. For example, the reactions of heterocyclic systems often result in substantial reorganization of their structural frameworks, e.g. ring expansion or contraction. The formation of acyclic products from ring systems (or vice versa) is also observed. 

Determine expansion or contraction losses, if any, including tank or vessel entrance or exit losses from Figures 2-12A, 2-15, or 2-16. Convert units to psi, head loss in feet times 0.4331 = psi (for water), or adjust for Sp Gr of other liquids. 

No expansion or contraction losses (except control valve). 

Large vessels and equipment operating at extreme temperatures exhibit large expansion or contraction movements. Any insulant specified for these applications should be capable of a sympathetic movement such that it will not cause itself or any cladding to burst, nor should it produce gaps that lead to dangerous hot spots in the cladding system. 

An influence on dimensions and tolerances involves the coefficient of linear thermal expansion or contraction. This CLTE value has to be determined at the product s operating temperature (Chapter 2, THERMAL EXPANSION AND CONTRACTION) Plas tics can provide all extremes in CLTEs. As an... 

Expansion or contraction can be controlled in the plastic by orientation, cross-linking, adding fillers and/or reinforcements, etc. Any cross-linking has a substantial beneficial ef-... 

Plastics can also be combined with other materials such as aluminum, steel, and wood to provide specific properties. Examples include PVC/wood window frames and plastic/ aluminum-foil packaging material. All combinations require that certain aspects of compatibility such as processing temperature and linear coefficient of thermal expansion or contraction exist. 

The CLTE is an important consideration if dissimilar materials like one plastic to another or a plastic to metal and so forth that are to be assembled where material expansion or contraction is restricted. The CLTE is influenced by the type of plastic (liquid crystal, for example) and RP (particularly the glass fiber content and its orientation). It is especially important if the temperature range includes a thermal transition such as Tg. Normally, all this activity with dimensional changes is available from material suppliers. 

Dilatometer Basically it is a pyrometer equipped with instruments to study density as a function of temperature and/or time. It can measure the thermal expansion or contraction of solids or liquids. They also study polymerization reactions it can measure the contraction in volume of unsaturated compounds. It basically is a technique in which a dimension of a material under negligible load is measured as a function of temperature while it is subjected to a controlled temperature program. 

A constant temperature may be recognised by unchanging volume in the apparatus of 1, a rising or falling of temperature by expansion or contraction. Used in this way the apparatus may be called a thermoscope. 

The pressure at every instant during an expansion or contraction of the working substance must be only infinitesimally greater or less respectively, than the external pressure, otherwise turbulent motions occur, the kinetic energy of which is ultimately converted into heat by friction, and this heat production is intrinsically irreversible. 

As described above, protein domains that provide discrete biological cues (e.g., cell binding) or mechanical properties (e.g., expansion or contraction with temperature changes) can be borrowed from nature and designed into synthetic polypeptides or joined with other polymers to provide bio-inspired function in new... 

---