Sporadic demand

In this overview article we only briefly discuss sporadic demand. We also do not deal with leaking demand or the like. However, the concepts and methods presented in the following sections for regular (i.e., plain) random demand can be extended to sporadic, seasonal and other sorts of demand. These extensions are natural but require much more difficult calculations. 

A frequently used model of sporadic demand is its description by two densities, a demand density <5 which describes the demand in the periods where it is not zero, and a discrete density r which gives the integer distance between periods with positive demand. 

A random demand is not sporadic with respect to a period length if we can expect that the outcome for a period is almost surely greater than zero. In other words 8 (0) = 0 which does not mean that the outcome 0 is impossible if you throw a dice with infinitely many faces then any outcome has probability 0. 

A continuous demand density 8 is called regular if 8 (0) = 0. Otherwise it is called sporadic. 

The energy requirements of each application are strongly connected to the size of the farm, type of activity and degree of automation. The power demand of such applications can vary from 700 W to 40 kW. The autonomous power system supplying an agricultural application should be able to serve heavy electric loads on a daily basis. In some cases, it is useful to split the loads in two categories (loads with continuous use and heavy sporadic use). Furthermore, in most cases the loads have strong seasonal variations of up to 70%. 

The next problem is investment. To build a refinery requires a massive investment of capital. In the past, refinery profits have been sporadic and profit margins have often been low. The prospect of low or no profits doesn t encourage investment. However, today s environment of high demand and tight supply points to steady profitability. However, that profitability is compromised when some refiners don t produce enough of their own crude oil to refine and must buy it at widely fluctuating prices. 

Solar electric plants shall be understood to be photovoltaic energy converters that are able to self-sufficiently satisfy a mean energy demand over a signihcant period of time, be it an appliance that is permanently hooked up or just for sporadic power supply of appliances. Such plants have in common that their input and output quantities fluctuate widely. They can therefore only be dimensioned on the basis of a mean value and are not able to satisfy this demand without the possibility to store energy. 

Sporadic change in the energetically-preferred mechanism may take place after altering a substituent due to the availability of two pathways of similar energy with very different electronic demands. This will result in a sudden change in the slope of the Hammett plot. Changes in the rate-determining step of a multi-step reaction or a unique reaction pathway will also result in discontinuity. 

Classroom observations, general observations and field notes were made throughout the research. While all students were happy to be interviewed and observed, the secondary students were not willing to participate in the planned diary scheme. Greg and Jerry made one or two sporadic entries, via computer or scribe, in the first term, but then found the work too onerous on top of all the demands of the curriculum. Mike did not want to take part at all, since he felt included at Meadow Hill anddidnot want to dwell on things which made him different. 

Reports on general chiral auxiliaries for the diastereoselective hetero-Diels-Alder reaction have been more sporadic than those of chiral auxiliaries developed for the parent Diels-Alder reaction (Section 17.4). Tietze demonstrated that an (-)-ephedrine-derived auxiliary functioned as an excellent controller group in the Et2AlCl-catalyzed inverse-electron-demand cydoaddition reaction of enone 216 (Scheme 17.30) [112]. After the formation of 217 (dr >98 2), the auxiliary could be readily excised by hydrolysis to give chiral lactone 218. 

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