Suboptimal design

It is interesting to note that this suboptimal design uses less catalyst than the optimum design. This occurs because the average temperature in the reactor is higher since the inlet temperature is higher (483.4 K vs. 474.7 K). Figure 6.26 shows the temperature... 

The effect of geometric parameters on the adiabaticity of a test reactor can be deduced from Table V. It can be seen that for improperly designed laboratory reactors the axial and radial heat flows can be quite appreciable even when the net heat loss is zero. From this table it follows that the radial heat flow is reduced as the bed diameter is increased, whereas the axial heat flow diminishes as the reactor length is increased. Hence, long pilot plant reactors of wide diameter will perform best as adiabatic reactors even with suboptimal design of compensation heaters. 

For the scope and depth of the product file of a pharmacy preparation, no strict rules exist yet. However, the pharmacist should clearly cmmect the solidity of the investigation and documentation to the extent of the risk of a suboptimal design or suboptimal control strategy. A risk based approach leads for instance to the following practical solutions as they occur in the Netherlands. 

In this synthesis, the broader context of the project (e.g., environmental concerns, customer expectations, return on investment) is integrated with the important details such as the type of heat-transfer medium or the number of stages in a column. It is crucial to consider as many alternatives as possible in the early stages to try to avoid becoming trapped in a suboptimal design. 

Thus far in this chapter, the holdup per tray is kept constant at 1000 mol when the number of reactive trays is increased in an attempt to improve the dynamics of the CS7-RR structure. This means that the suboptimal design (5/10/5) has a total of 10,000 mol of reactive holdup and the optimal design (5/7/5) has a total of 7000 mol. The question that arises is what if the total holdup of the optimal design is kept the same and just distributed over a larger number of trays ... 

To see what effect this has, the molar holdup of the 5/10/5 case is decreased from 1000 to 700mol/tray. Figure 10.12 shows the steady-state gains and Kpos) between tray temperatures and feed flowrates for these two cases. The upper plot shows the case where the suboptimal design has lOOOmol/tray. The lower plot shows the case where the total holdup is kept the same as the optimum case, so each tray has 700 mol. The shapes of the steady-state gain curves of these two cases are similar in terms of signs and magnimdes... 

Design of the physical environment (e.g., heat, noise, lighting), to minimize the negative physical and psychological effects of suboptimal conditions... 

As with studies of many other herbs and nutritional supplements, interpretation of clinical trials of valerian is hampered by small sample sizes, suboptimal study design, lack of specified inclusion and exclusion criteria, and unknown composition of valerian extract (Plushner, 2000). Furthermore, none of the trials have included children or teenagers. Nevertheless, several studies have showed a mild hypnotic action in persons with insomnia and in normal sleepers, as well as a mild sedative effect (Leathwood and Chauffard, 1983, 1985 Balderer and Borbely, 1985). One report has described an anxiolytic effect (Kohnen and Oswald, 1988). There are suggestions that valerian may have beneficial effects on sleep latency, frequency of waking, nighttime motor activity, and overall sleep quality. 

The spectral characteristics of BODIPY FL IA somewhat mimic the green luminescence of fluorescein, thus the FL designation in its name. The excitation maximum for the probe occurs at 504 nm, and its emission at 510 nm. The extremely small Stokes shift makes it difficult to avoid problems of excitation-light interference in critical emission measurements unless suboptimal excitation wavelengths below its excitation maximum are used. The molecule has an extinction coefficient in methanol (containing 1% sodium acetate and 1% 2-mercaptoethanol) of about 79,000 M 1cm 1 at 504 nm. 

The primary limitation however of sequential synthesis methods is that different costs associated with the design of HENs cannot be optimized simultaneously, and as a result the trade-offs are not taken into account appropriately. Early decisions in the selection of HRAT and partitioning into subnetworks affect the number of units and areas of the units in the HEN configuration. Therefore, sequential synthesis methods can often lead to suboptimal networks. 

The first example is a case study in the molecular design of fuel additives. Through the combustion process, undesirable largely carbon-based molecular fragments are created that are deposited on the surface of the intake valve. Over time these deposits accumulate and eventually inhibit the proper opening and closing of the valve, resulting in suboptimal combustion and noxious gas releases. 

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