Time-based initiatives

When a company attacks time directly, the first benefits to show up are usually shorter cycle times and faster inventory turns. Lower overhead costs usually follow, as the costs of dealing with breakdowns and delays begin to disappear from the system. So by seeking time reduction, both time reduction and cost reduction are often the rewards. 

Attacking the sources and causes of delays helps reduce quality defects in product and service. Thus by focusing on time, customers needs are met more quickly and a quality benefit will often accompany the time benefit. 

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One of the aims of a time-based initiative is often to minimise how much forecasting is needed. By reducing the production lead time, the period when demand is uncertain becomes shorter. Forecasting over a shorter time period results in a more reliable forecast and therefore less risk of stockouts or obsolete stock. It also reduces the amount of finished goods stock needed, which frees up working capital. 

This does not mean to say that all operations in the supply chain need to be subject to time compression. In the example shown in Figure 5.11, the new delivery cycle times (shown with a dotted line) actually increase in the new stmcture. But this suboptimisation is allowable, as traditional distribution from local warehouses here is replaced with direct delivery from the factory, where products are made to order. The transition to make to order replaces the need for inventoryholding points, where goods typically are stored for extensive periods of time. Of course this basic example also indicates how time-based initiatives can require structural supply chain redesign, such as the reconfiguration of distribution channels and the adjustment of manufacturing systems and policies. 

Thickness of the laminar layer is deterrnined both by the need to reproduce fine detail in the object and by the penetration depth of the actinic laser light into the monomer bath (21,76). There is thus a trade-off between precision of detail in the model and time required for stereohthography, ie, the number of layers that have to be written, and an optimum Light-absorbing initiator concentration in the monomer bath corresponding to the chosen layer thickness. Titanocene-based initiators, eg, bis-perfluorophenyltitanocene has been recommended for this apphcation (77). Mechanistic aspects of the photochemistry of titanocenes and mechanisms of photoinitiation have been reviewed (76). 

Juice-Based Flavors. Fmit juices are concentrated for use ia carbonated beverage flavors. The final juice is concentrated between four to six times its initial strength by removing the water under vacuum it is then pasteurized. Orange, grapefmit, lemon, grape, and apple are the most common fmit juices used ia carbonated beverages. 

The initial measurement of electrical resistance must be made after considerable time. Phenomenological information has been determined based on the corrosion rate expected at what period of time to initiate readings of the electrical resistance. Since these values are based on experiential fac tors rather than on fundamental (so-called first) principles, correlation tables and lists of suggested thicknesses, compositions, and response times for usage of ER-type probes have developed over time, and these have been incorporated into the values read out of monitoring systems using the ER method. 

Filter life Measure of the duration of a filter s useful service. This is based on the amount of standard contaminant required to cause differential pressure to increase to an unacceptable level-typically 2-4 times the initial differential pressure, a 50-80% drop in initial flow, or a downstream measure of unacceptable particulate. Filter media A porous material for separating suspended particulate matter from fluid. 

In an enclosure, a peak for initial pressure ratio for a deflagration generally can exceed 8 1 of the initial pressure. The pressures may build to a ratio of 40 1 (reflected pressure) times the initial pressure when a detonation develops. This is the reason detonations can be so disastrous. Their final pressure, when built on a deflagration peak pressure as a base or initial pressure, can be extremely high. 

The production-scale fermentation unit, with a projected annual capacity of over50,000 tonnes was fully commissioned in 1980. The bioreactor (Figure 4.8) is 60 m high, with a 7 m base diameter and working volume 1,500 m3. There are two downcomers and cooling bundles at the base. Initial sterilisation is with saturated steam at 140°C followed by displacement with heat sterilised water. Air and ammonia are filter sterilised as a mixture, methanol filter sterilised and other nutrients heat sterilised. Methanol is added through many nozzles, placed two per square metre. For start-up, 20 litres of inoculum is used and the system is operated as a batch culture for about 30 h. After this time the system is operated as a chemostat continuous culture, with methanol limitation, at 37°C and pH 6.7. Run lengths are normally 100 days, with contamination the usual cause of failure. 

The initial measurement of electrical resistance must be made after considerable time. Phenomenological information has been determined based on the corrosion rate expected at what period of time to initiate readings of the electrical resistance. Since these values are... 

A water-expandable material based on bentonite clay and polyacrylamide is added to the circulating drilling solution [118]. The material expands in water to 30 to 40 times its initial volume. The swelling takes place within 2 to 3 hours. During the circulation of the drilling solution, the material enters the cracks and... 

Note that the initial slope of the adsorption isotherm can be easily obtained from the knowledge of the retention time associated to a small injection performed on a column, as this retention time is given by tR = t0 ji + 1 - -k where /0 = V/Q is tiie zero-retention time based on the external bed porosity e (commonly, e is about 0.36-0.4). 

This latter differential equation, coupled with the algebraic expression relating qout to h, may be solved to determine the fluid height as a function of time. The initial fluid height is 50.93 m, based upon the specified initial fluid volume and tank diameter. This serves as the initial condition to be used for the integration. The E-Z Solve syntax is ... 

The problems encountered in the catalytic transfer of highly hydrophilic anions from aqueous solutions into the organic phase can be countered by the use of anhydrous solid salts the organic reactant is dissolved in the organic solvent or, if liquid, may be used neat. Solid liquid two-phase reactions using ammonium salts have widespread application (see, for example, the many examples cited in later chapters) frequently with shortened reaction times, lower reaction temperatures, and higher yields [e.g. 66, 67] and are generally superior to solidrliquid reactions catalysed by crown ethers [68]. The process is particularly useful in base-initiated reactions with fluorides, hydroxides or carbonates. 

Kinetics show that the reaction is pseudo-first order in the RX concentration and that there is a linear correlation in the rate of consumption of RX with the concentration of the catalyst. The need for a high rate of stirring indicates that, as discussed in Chapter 1, the base-initiated formation of the cobalt tetracarbonyl anion results from an interfacial exchange process. It is significant that, when preformed NaCo(CO)4 is used, the extractability of the anion by benzyltriethylammonium cation into diisopropyl ether is three times less efficient than it is into benzene or dichloromethane, but kinetic studies show that, in spite of the lower concentration of the anion in the ether, the rate of reaction with RX in that solvent is generally higher [3]. 

On the diagram the height II above the base is plotted against time. The initial height is given by OA (90 cm) and the initial constant slope of the curve gives the sedimentation velocity (uc)o for a concentration of 200 kg/m3 (c0). 

The most widely studied transition metal is titanium. At various times, all oxidation states of titanium (II, III, IV) have been proposed for the active site of titanium-based initiators. Most of the evidence points to titanium (HI) as the most stereoselective oxidation state, although not necessarily the most active nor the only one [Chien et al., 1982]. (Data for vanadium systems indicate that trivalent vanadium sites are the syndioselective sites [Lehr, 1968].) Initiators based on the a-, y-, and 8-titanium trihalides are much more stereoselective (iso-selective) than those based on the tetrahalide or dihalide. By itself, TiCl2 is inactive as an initiator but is activated by ball milling due to disproportionation to TiCl3 and Ti [Werber et al., 1968]. The overall stereoselectivity is usually a-, y-, 8-TiCl , > TiCL > TiCLj P-TiCl3 [Natta et al., 1957b,c],... 

Atom Transfer Radical Polymerisation (ATRP) was discovered independently by Wang and Matyjaszewski, and Sawamoto s group in 1995. Since then, this field has become a hot topic in synthetic polymer chemistry, with over 1000 papers published worldwide and more than 100 patent applications filed to date. ATRP is based on Kharasch chemistry overall it involves the insertion of vinyl monomers between the R-X bond of an alkyl halide-based initiator. At any given time in the reaction, most of the polymer chains are capped with halogen atoms (Cl or Br), and are therefore dormant and do not propagate see Figure 1. 

The synthetic implications of this discovery were slow to be exploited. Base-initiated dimerizations of 2-cycloalkenones, known to give crystalline solids,3233 remained puzzling for some time before conjugate additions were suggested to account for some of the possible products 34 indeed, the product of base-catalyzed dimerization of 4,4-dimethyl-2-cyclopentenone, which proceeds via a double Michael addition sequence, was not identified until 1969 (Scheme 2).35 An unanticipated cyclopropanation reaction of acrylaldehyde36 37 using ethyl bromomalonate and proceeding by means of a similar Michael addi-tion-Sw enolate alkylation represents an early synthetic use of tandem vicinal difunctionalization. 

Calculation of residual stresses in crystallizable materials is primarily based on the assumption that these materials can be treated as a two-component mixtures of initial and final products, as indicated in Eq. (2.97). In this case, the share of both components is determined by the degree of crystallinity a, which is changing in time. The initial product is a melt, for which a = 0 the final... 

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