Set Up Time

SPMs are simpler to operate than electron microscopes. Because the instruments can operate under ambient conditions, the set-up time can be a matter of minutes. Sample preparation is minimal. SFM does not require a conducting path, so samples can be mounted with double-stick tape. STM can use a sample holder with conducting clips, similar to that used for SEM. An image can be acquired in less than a minute in fact, movies of ten fiames per second have been demonstrated. ... 

Ease of use 2-6°C storage. Multiple application devices (linear, spray tips, endoscopic, etc.), 20 min preparation time. Set-up time = 30 s-3 min. May wash away in presence of active bleeding. Requires trained personnel to operate equipment. Preparation time required to obtain plasma component. Room temperature storage. 5 min preparation time. Single syringe applicator per kit. Set-up time - 3 min. Effective at site of active bleeding. 

Rajagopaian, D., and Karimi, I.A., Completion times in serial mixed-storage multiproduct processes with transfer and set-up times. Comput. Chem. Eng. 13(1/2), 175-186 (1989). 

Consider two products A and B with the same demand of 20 units per time period, the same buffer size of 60 units, and the same production speed and set up time. The only difference is that product A is only sold in single units, but product B has 80% of orders of 1 unit and 20% of orders of 10 units. It is intuitively clear that product B will have a lower service level because is has a larger variance of the demand. It is not immediately clear that both products have different optimal lot sizes. The optimal lot size, i.e., the lot size resulting in maximal service, is 20 units for product A which results in a /3-service level of 98.6% (Figure 6.8). The optimal lot size for product B is 15 units which results in a not particularly good /3-service level of 90.6%. In order to achieve a /S-service level of 98.6% one would need a buffer of size 165 units, with a corresponding optimal lot size of 33. 

Each of the two finishing lines is dedicated to one EPS-type A or B. The separation units have to be provided with a permanent feed with a rate between 0.10 and 0.25 polymerization batches per hour. The residence time in a separation unit is 24 h regardless of the feed rates. A start-up as well as a shut-down of a separation unit requires a set-up time of 24 h. 

Changeovers No changeovers appear in the preparation stage and in the polymerization stage. The start-ups and shut-downs of the finishing lines are changeovers with certain set-up times which cause costs (see below). 

Total time available (for production and setup) in each week is 80 h. Starting inventory is zero, and inventory at the end of week 4 must be zero. Only one product can be produced in any week, and the line must be shut down and cleaned at the end of each week. Hence the set-up time and cost are incurred for a product in any week in which that product is made. No production can take place while the line is being set up. 

These combinatorial problems, and many others as well, have a finite number of feasible solutions, a number that increases rapidly with problem size. In a job-shop scheduling problem, the size is measured by the number of jobs. In a traveling salesman problem, it is measured by the number of arcs or nodes in the graph. For a particular problem type and size, each distinct set of problem data defines an instance of the problem. In a traveling salesman problem, the data are the travel times between cities. In a job sequencing problem the data are the processing and set-up times, the due dates, and the penalty costs. 

Comparisons between AAS instruments and the Jerome show statistically equivalent results. The Jerome gives accurate results for samples with a mercury content of less than 1 ppb and requires less work space, set up time, chemical reagents and sample size. 

TTie HP 6890 series features electronic pneumatics control which provides complete electronic control of all gas pressures and flows. On-board sensors automatically compensate for ambient temperature changes and barometric pressure differences to provide more accurate and reproducible results routinely. This reduces recahbration frequency and improves laboratory productivity. It also decreases system operating costs, allows a faster set-up time, and reduces equihbradon time after set-points are changed from one method to the other. 

A five-method storage capabihty for all GC set points reduces set-up time and increases reproducibihty. 

Lap shear testing Shear can be applied in a number of ways cyclic, intermittent, static (or constant), or increasing. A simple overlap shear test is described in ASTM-D-1002. This can be illustrated again using two strong microscope slides. Here, the microscope slides are adhered in parallel to one another except offset. After the appropriate set-up time, the top and bottom of the slide combination are attached to the shear tensile-measuring device and the experiment is carried out. 

Greater efficiency (sample preparation time, run set-up time, instrument time). 

Average profit, /hr = Amount of distillate product, kmol = sales value of the product, /kmol = initial raw material charge, kmol = cost of raw material, /kmol = fixed operating cost, /hr = batch time, hr = set up time, hr... 

Table 5.6 presents the results of a set of 5 maximum profit problems considered by Kerkhof and Vissers (1978). Each problem has different column configuration (i.e. different number of plates, N), handles different feed mixture (characterised by different relative volatility, a)y has different distillate product quality (xq), has different cost values (i.e. Pr, C0) and different set up times (ts). The initial charge, B0 = 100 kmol, V= 60 kmol/hr, t,= 1 hr, and Cf= 150 /hr. All cases deal with binary mixtures of different initial composition, xB0. 

H and Fm given - Larger B0 will always be favoured (for finite set up times), because the idle time for the plant is reduced and because the capital costs typically increase with capacity by an exponent less than 1 (economy of scale). The optimum value of B0 will depend on constraints 7.14-7.18. 

Therefore only two time periods are involved in the optimisation problem formulation, one for each mixture. Instantaneous switching occurs between batches and therefore set up time between the batches is ignored. The profit function does not include the allocation of time to each separation. For each mixture (m) individual profits (Pm) were maximised to maximise the overall profit. 

Combination of Allocation Time with Zero Set up Time... 

Comparison of the results in Table 7.9 with those in Table 7.7 (and Table 7.8) and Table 7.4 show significant differences in the design, operating policies, optimal recoveries of products, number of batches to be processed for each duty and total yearly profit. This clearly shows the importance of including allocation time and set up time between batches in the objective function. It is to be noted that in all cases a simple model but detailed plate-to-plate calculations (Type HI) with reasonable column holdup is used (unlike a short-cut model ignoring column holdup as in Logsdon et al.). 

The set-up time for both policies is 30 min. In both policies, all productions are achieved on specification. The instantaneous composition in each vessel and the optimum instantaneous QM profiles for Policy 1 are shown in Figure 11.12. For... 

The maximum capacity of the MultiVBD column is 10 kmol and has 4 vessels including the reboiler and condenser holdup tank (3 column sections). Both conventional and the MultiVBD columns are available for a period of 8000 hrs/Yr- The set up time for each batch of operation is 30 minutes. The total number of batches will therefore be 979 per year and the individual batch time would be 7.67 hr. 

Rajagopalan, D., and Karimi, I. A. (1987), "Scheduling in Serial Mixed Storage Multiproduct Processes with Transfer and Set-up Times," Computer-Aided Process Operations, New York CACHE/Elsevier, 679. 

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