Demand pattern

Since the bulk of butadiene is recovered from steam crackers, its economics is very sensitive to the selection of feedstocks, operating conditions, and demand patterns. Butadiene supply and, ultimately, its price are strongly influenced by the demand for ethylene, the primary product from steam cracking. Currently there is a worldwide surplus of butadiene. Announcements of a number of new ethylene plants will likely result in additional butadiene production, more than enough to meet worldwide demand for polymers and other chemicals. When butadiene is in excess supply, ethylene manufacturers can recycle the butadiene as a feedstock for ethylene manufacture. 

Equally, if the demand only rarely exceeded 4000 kg, or fell below about 1000 kg, it would be possible to set the larger valve at the higher pressure and supplement the supply through the smaller valve on those few occasions when this was necessary. Sometimes the demand pattern is not known, except for the minimum and maximum values. Usually valves are then chosen with capacities of one third and two thirds of the maximum. The smaller valve is set at the slightly higher pressure. 

Especially in the process industries various stochastic methods can be applied to cope with random demand. In many cases, random demands can be described by probability distributions, the parameters of which may be estimated from history. This is not always possible, the car industry is an example. No two cars are exactly the same and after a few years there is always a new model which may change the demand pattern significantly. 

Demand patterns Multiple product demands appear which are specified by their amounts and their due dates. 

Demand patterns can also vary significantly ranging from cases where due dates must be obeyed to cases where production targets must be met over a time horizon (fixed or minimum). Changeovers are also a very important factor, which is particularly critical in cases of transitions that are sequence dependent on the products, as opposed to simple setups that are only unit dependent. 

Batch processing time Demand patterns Changeovers Resource constraints Time Constraints Costs... 

Table 5-2. Demand Patterns for Major Petroleum Products (1992)a...

On the demand side, consumption has experienced less noticeable shifting of traditional patterns, but environmental restrictions, new process developments, and world economics have all imposed some alterations on end uses. In addition to these changes, recent political difficulties have adversely affected some of the major world suppliers of sulfur. Clearly, the balance between sulfur supply and demand, which has traditionally been somewhat variable, is now more unstable because the potential exists for major shifts in supply/demand patterns. 

The large number of herbs that are available for customers, combined with the relatively low volumes required, means that it may not be economically viable for an extract manufacturer to cany production volumes of large number s of extracts on the off-chance that someone will want one or two of them before then shelf-live has expired. The usual practice is for extract manufacturers to carry a fairly wide range of dried herbs in sample quantities so that when a customer asks for a sample it can be produced within a reasonably short time. Once a new herbal drink has been developed using samples and perhaps a pilot batch, a production-size batch of extract will be made for the product launch. After that, if the product sells and there is a demonstrable demand pattern, it is possible that the extract manufacturer will agr ee to make a batch for stock to be called off by the drink manufacturer. 

Starches Derivatives. Global Supply/Demand Patterns 2003-2010 GIRACT, 24 Pre-Colomb, CH-1290 Versoix/Geneva Switzerland, www.giract.com. 2004. 

Petroleum coke markets are developed around a demand hierarchy that consists of several end-uses. Premium markets, including the use of calcined petroleum coke, will continue to be cyclical. As such, demand patterns for petroleum coke will remain volatile. 

II. Likely trends in alkylation capacity m view of gasoline lead regulations, demand patterns, etc. 

The use of preliminary screens can eliminate the vast majority of compounds before more rigorous, and computationally demanding, pattern-matchingcomparisons(212,213). 

The ability to vary oxygen enrichment levels instantaneously also provides the cupola or blast furnace operator with an extremely flexible device to control furnace operations better in spite of unavoidable changes in coke and metallic charge quality, blast humidity and temperature, and cast house demand pattern. Today, hundreds of cupola foundries worldwide use oxygen to increase cupola capacity and/or reduce unit operating cost, and most modem blast furnaces are equipped with oxygen injection. 

For instance, p-cresol based BHT as an antioxidant will continue to dominate the demand pattern of p-cresol however, two recent developments have put this in doubt. The Food and Drug administration of USA has removed BHT from its GRAS (Generally Regarded As SAFE) list of foodstuff additives on the grounds of suspected carcinogenic properties. This has caused diminished demand of 15% of BHT in USA [8]. 

When comparing the competing processes for making hydrocarbons from synthesis gas - the Fischer Tropsch CO hydrogenation and the MTG conversion -the process flow sheets show as the main difference the additional step of methanol synthesis for the MTG route. However, product selectivity is basically different for both the conversions. And from this point of view the one or the other route can be the more favourable option as fitting best the particular demand pattern. Selectivity differences fundamentally result from the different kinds of chemistry which are involved Hydrogenation on special metal type catalysts in case of the Fischer Tropsch reaction and a conversion via car-benium ion intermediates on acidic sites, which is additionally constrained by shape selectivity in case of the MTG process. 

Shrinking transistor size demands pattern definition tools that can print increasingly smaller features. However, increasing resolution for smaller features is obtained at the expense of the depth of focus. Depth of focus is the vertical range over which the image will be in acceptable focus (i.e., the image will adequately print). If the mask feature cannot be adequately imaged on... 

Total operation, maintenance, and amortization costs at the estimated actual load factor for the first year of the Buckeye plant s operation (48% of theoretical full-load capability) will be 50.9 cents per 1000 gallons. Operation at 98% of theoretical full-load factor (the plant s maximum practical capability) would result in total costs of 33 cents per 1000 gallons (Table II). The 33 cent figure can be compared with previous cost estimates made by this company (I, 2, 5), the Office of Saline Water (8), or others (9), who have usually assumed full-load or virtually full-load operation in such calculations. Most of the factors making up this cost estimate have been guaranteed to the town of Buckeye. However, the 48% load faotor is an estimate based on the historical demand pattern for untreated water around the year. It is difficult without actual experience over the next year or two to predict the effect, if any, of a substantial rate rise on the usage of water and the load factor. 

Ecological Aspects of the Catalyst Change. The decreasing demand for ortho-chlorotoluene has limited the possibilities for utilizing the excess material. The effect on cost that would result from incineration of orf/io-chlorotoluene had to be assessed. With this background, the development of new benzothiazepine cocatalysts relieved the isomer problem at just the right time. The isomer ratio has now been moved in the desired direction and adapted to the demand pattern. No incineration of an undesirable product is necessary. 

Extensive research on coordination of resource allocation has been published in connection with scenarios of multiple resource providers and consumers. In the research, existence of demand patterns is the prerequisite for deciding which algorithm is applicable. The selection of a certain algorithm is often left to empirical judgment, which does not alleviate difficulties in balancing utilization and level of services (e.g., meeting due dates). 

Once the work has been scheduled in areas where work scheduling is possible and the staffing requirements have been determined based upon the scheduled work, the next step is to determine which individuals will work which hours and on what days. This step is called personnel scheduling. In other areas of the hospital, such as the emergency room, where work cannot be scheduled, staffing requirements are determined using historical demand patterns by day of the week and hour of the day. The next step again is to determine the schedule for each staff member. 

The quantity of work to be done must be defined by the appropriate time period, which could be by as little as a 15-minute interval for cashiers and as long as a day for paper mills. For continuous process industries, such as chemical plants and some mining processes, the definition of what is needed is relatively easy to determine. Even so, the work must be defined by the hour and day of the year to allow for maintenance and shutdowns for holidays. There are many other industries that also have a well-known stable demand for work profile—for example, prisons, long-term health care facilities, and many manufacturing systems, such as assembly lines. At the other end of the scale are situations such as retad outlets and telephone operators, that have a demand that varies constantly during the day, and from day to day, and from season to season. Many of the organizations with such a fluctuating demand pattern have a detailed data bank of historic data, usually by the 15-minute interval. These data can be used to predict the work requirements for future time periods. 

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