Practical rules of thumb

A practical rule of thumb is that the rate of change doubles with every 10° rise in temperature. However, stability tests are rarely run at temperatures exceeding 50°C, since too drastic deviations from normal storage conditions cause distortions in the predictions of stability. 

Computer Network Infrastructure IT Infrastructure Best Practice Rule of Thumb 20% Perez Fiorito ... 

The ratio VqA/ c is the total porosity of the column. It is a dimensionless number that should be somewhere between 0.7 and 1. If the ratio is found to be higher than unity, it means the dead volume is overestimated the solute used was retained. If the Vq/Vc ratio is found to be lower than 0.7, the dead volume is too small. The test solute was probably excluded from the internal pore volume of the stationary phase. A practical rule of thumb for the 4.6 mm i.d. column only is [7] ... 

Limitations—Practical Rule of Thumb. It is useful to have a practical limit to express an understanding of where the technologies may limit performance. In the case of etched linewidth, it has been expressed that the total of the resist thickness pins the etched foil thickness wonld limit the gap between the etched features. Therefore, for 1.2-mil dry-film resist over 1-oz copper foil, the total thickness is 2.6 mil. This conld be nsed as a practical limit for both the trace and gap. Further limits can be determined by the nndercnt and etch factor experienced for the same type of etched featnres. Therefore, nsing the R/B = 1 data from Table 34.2 (17= 0.525 mil), a 2.6-mil resist line wonld be 2.6 mil at the trace bottom and would have a 1.5-mil etched top reduction, leaving only a 1.1-mil top snrface. It mnst then be determined if these dimensions (with allowance for variations) are snfficient for the design functionality. 

A breaker, usually an MCCB or an MCB on an LT system, can be provided with backup HRC fuses to enhance their short-time rating. This may be done when the available MCCBs or MCBs possess a lower short-time rating than the fault level of the circuit they are required to protect, and make them suitable for the fault level of the circuit. But this is not a preferred practice and is seldom used. As a rule of thumb, the device that is protecting must be suitable to withstand electrically and endure mechanically the system fault current for a duration of one or three seconds, according to the system design. 

T he use of LCA for communicating environmental achievements to interest groups is an important option. In many practical situations, LCA requires much time and effort, and more simple rules of thumb are needed.. Some of these use Environmental Performance Indicators, the so-called EPIs. LCA can be used to full advantage to develop EPI-based rules of thumb. ... 

Rules of thumb regarding scale-up and good design practice are not suitable for determining cost of performance design or physical capital cost. 

Depending on construction and orientation of stress relative to reinforcement, it may not be necessary to provide extensive data on time-dependent stiffness properties since their effects may be small and can frequently be considered by rule of thumb using established practical design approaches. When time dependent strength properties are required, creep and other data are used most effectively. There are many RP products that have had super life spans of many decades. Included are products that have been subjected to different dynamic loads in many different environments from very low temperatures to very high corrosive conditions, etc. An example is aircraft primary structures (10,14,62). 

In practice, however, it is often the case that for small LP steam heating boiler systems with a very high percentage of CR, and in those regions of countries where soft water is supplied, no water softener is provided or deemed necessary. Instead there is merely a reliance on internal chemical treatments (or sometimes magnetic devices or other types of gadget ). A good rule of thumb is ... 

As will be outlined below, the computation of compressible flow is significantly more challenging than the corresponding problem for incompressible flow. In order to reduce the computational effort, within a CED model a fluid medium should be treated as incompressible whenever possible. A rule of thumb often found in the literature and used as a criterion for the incompressibility assumption to be valid is based on the Mach number of the flow. The Mach number is defined as the ratio of the local flow velocity and the speed of sound. The rule states that if the Mach number is below 0.3 in the whole flow domain, the flow may be treated as incompressible [84], In practice, this rule has to be supplemented by a few additional criteria [3], Especially for micro flows it is important to consider also the total pressure drop as a criterion for incompressibility. In a long micro channel the Mach number may be well below 0.3, but owing to the small hydraulic diameter of the channel a large pressure drop may be obtained. A pressure drop of a few atmospheres for a gas flow clearly indicates that compressibility effects should be taken into account. 

As a rule of thumb, a difference of 4 cm"1 in the Raman spectrum corresponds to a wavelength shift of 0,1 nm in the measured spectrum. To distinguish two spectral features 50 cm 1 apart, full spectral separation must be achieved over an interval of less than 2 nm. This effectively excludes filter solutions. Therefore, Raman arrangements practically always rely on spectrometers for spectral analysis. 

There are several areas where a therapeutic relationship can typically go wrong and cause ethical concerns. The first area of concern has to do with finances. Since counseling and therapy often involve payment, it is important to try to divorce therapy as much as possible from the financial aspects of the business of therapy. However, this is not always possible, especially if you are in private practice and you are your own accountant, too A rule of thumb is this If you cannot treat a client without bias because bills are not being paid, then you have no business treating the client any longer. A therapeutic referral must be made. There is no possible way that you can give your best effort to a client when you are sore about not getting paid. 

This example examines a simple problem in detail so that you can understand how to execute the steps for optimization listed in Table 1.1. You also will see in this example that optimization can give insight into the nature of optimal operations and how optimal results might compare with the simple or arbitrary rules of thumb so often used in practice. 

Suppose you wanted to find the configuration that minimizes the capital costs of a cylindrical pressure vessel. To select the best dimensions (length L and diameter D) of the vessel, formulate a suitable objective function for the capital costs and find the optimal (LID) that minimizes the cost function. Let the tank volume be V, which is fixed. Compare your result with the design rule-of-thumb used in practice, (L/D)opt = 3.0. 

The amount of biocides needed in an antifouling paint will be determined by actual tests performed in real life. A rule of thumb says that the minimum level of protection with copper is a leaching rate of 10 pg/(cm2 day) (WHOI, 1952). The amount of cuprous oxide can be up to 40 wt % of an antifouling paint and it is normally assisted by booster biocides (5 to 10 wt %) to provide full protection against both animals and algae. The amount of biocides will be based on practical performance and, at the same time, be restricted to given legislation. 

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