Discontinuous Process

J. E. Ferrell, Jr., and W. Xiong, Bistability in cell signaling How to make continuous processes discontinuous, and reversible processes irreversible. Chaos 11(1), 227 236 (2001). 

Classification according to the pressure used, the continuity of the process (discontinuous, semicontinuous, continuous, or automated), or the degree of finish (intermediate component, i.e., section, or finished product, e.g., foam) is also possible (see Plastics Handbook or BS, ASTM, or DIN standards.)... 

Classification according to the pressure used, the continuity of the process (discontinuous, semicontinuous, continuous, or automated), or the... 

Product complexity is accompanied by process complexity, which is characterized by the use of more and more complex tools, interfaces and specifications when thinking in term of compliance [83]. In some cases, process discontinuities have led to important delays of the start of production (SOP) of well-known airplanes and cars models. 

In batch techniques, the fermentor is filled with medium and inoculated the cells multiply and synthesize the product, simultaneously consuming the nutrients in the medium. At the appropriate time, the culture is drained off and processed. Discontinuous processes are used, e.g. in the production of antibiotics and certain amino acids, which are synthesized only during particular growth phases of the organism. Their discontinuity of operation makes them less suitable for industrial production than continuous processes. 

The fusing process is performed by special fusing presses. They can be divided into two groups according to the way they perform the work process discontinuous work process (flat) fusing presses and continuous work process fusing presses. 

In a batch process, the main steps operate discontinuously. In contrast with a continuous process, a batch process does not deliver its product continuously but in discrete amounts. This means that... 

There have been numerous efforts to inspect specimens by ultrasonic reflectivity (or pulse-echo) measurements. In these inspections ultrasonic reflectivity is often used to observe changes in the acoustical impedance, and from this observation to localize defects in the specimen. However, the term defect is related to any discontinuity within the specimen and, consequently, more information is needed than only ultrasonic reflectivity to define the discontinuity as a defect. This information may be provided by three-dimensional ultrasonic reflection tomography and a priori knowledge about the specimen (e.g., the specimen fabrication process, its design, the intended purpose and the material). A more comprehensive review of defect characterization and related nondestructive evaluation (NDE) methods is provided elsewhere [1]. 

An implicit edge process is involved in the regularization process where A acts as a scale parameter which gives a constraint on the size of the homogeneous patches and p. comes from ho = -y/ p/A where ho is the threshold above which a discontinuity is introduced. We propose, then to combine these two functionals to obtain a satisfactory solution ... 

Figure 4.3b is a schematic representation of the behavior of S and V in the vicinity of T . Although both the crystal and liquid phases have the same value of G at T , this is not the case for S and V (or for the enthalpy H). Since these latter variables can be written as first derivatives of G and show discontinuities at the transition point, the fusion process is called a first-order transition. Vaporization and other familiar phase transitions are also first-order transitions. The behavior of V at Tg in Fig. 4.1 shows that the glass transition is not a first-order transition. One of the objectives of this chapter is to gain a better understanding of what else it might be. We shall return to this in Sec. 4.8. 

Because RPSA is appHed to gain maximum product rate from minimum adsorbent, single beds are the norm. In such cycles where the steps take only a few seconds, flows to and from the bed are discontinuous. Therefore, surge vessels are usuaHy used on feed and product streams to provide unintermpted flow. Some RPSA cycles incorporate delay steps unique to these processes. During these steps, the adsorbent bed is completely isolated and any pressure gradient is aHowed to dissipate (68). The UOP Polybed PSA system uses five to ten beds to maximize the recovery of the less selectively adsorbed component and to extend the process to larger capacities (69). 

Eor many pigments, a period of time in which they had their widest use can be indicated (54,62,63). Dates of introduction are known either from documentary sources or from identification on paintings of known dates. Eor some pigments, an approximate date for the discontinuation of use can be assigned. In some cases, knowledge of the preparation process or even the very existence was lost over an appreciable time span. 

The expansion process consists of three steps creating small discontinuities or cells in a fluid or plastic phase causing these cells to grow to a desired volume and stabilizing this cellular stmcture by physical or chemical means. 

Amalgamation, which was once widely used, has been largely discontinued because of inefficiency and environmental concerns. Gold in association with metals such as copper, nickel, and lead, generally follows these in the concentration process and eventually can be separated and recovered. 

Imperial Chemical Industries (ICI) operated a coal hydrogenation plant at a pressure of 20 MPa (2900 psi) and a temperature of 400—500°C to produce Hquid hydrocarbon fuel from 1935 to the outbreak of World War II. As many as 12 such plants operated in Germany during World War II to make the country less dependent on petroleum from natural sources but the process was discontinued when hostihties ceased (see Coal conversion PROCESSES,liquefaction). Currentiy the Fisher-Tropsch process is being used at the Sasol plants in South Africa to convert synthesis gas into largely ahphatic hydrocarbons at 10—20 MPa and about 400°C to supply 70% of the fuel needed for transportation. 

Commercial VPO of propane—butane mixtures was in operation at Celanese Chemical Co. plants in Texas and/or Canada from the 1940s to the 1970s. The principal primary products were acetaldehyde, formaldehyde, methanol, and acetone. The process was mn at low hydrocarbon conversion (3—10%) and a pressure in excess of 790 kPa (7.8 atm). These operations were discontinued because of various economic factors, mainly the energy-intensive purification system required to separate the complex product streams. 

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