Most Important Parameters

The most important process parameters are melt pressure and temperature. They are the best indicators of how well or how poorly an extruder functions. Process problems, in most cases, first become obvious from melt pressure and/or temperature readings. Just think what a doctor does when a patient comes into the office with a problem. Usually, the first check of the patient s condition is made by taking blood pressure and body temperature. These are two good indicators of the functioning of the human body. In the same fashion, melt pressure and temperature are good indicators of how the extruder is functioning. 

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Active solids are widely used as adsorbents of gases and vapours, and the specific surface is the most important parameter for characterizing their... 

Polarization which can be induced in nonconducting materials by means of an externally appHed electric field is one of the most important parameters in the theory of insulators, which are called dielectrics when their polarizabiUty is under consideration (1). Experimental investigations have shown that these materials can be divided into linear and nonlinear dielectrics in accordance with their behavior in a realizable range of the electric field. The electric polarization PI of linear dielectrics depends linearly on the electric field E, whereas that of nonlinear dielectrics is a nonlinear function of the electric field (2). The polarization values which can be measured in linear (normal) dielectrics upon appHcation of experimentally attainable electric fields are usually small. However, a certain group of nonlinear dielectrics exhibit polarization values which are several orders of magnitude larger than those observed in normal dielectrics (3). Consequentiy, a number of useful physical properties related to the polarization of the materials, such as elastic, thermal, optical, electromechanical, etc, are observed in these groups of nonlinear dielectrics (4). 

The maximum bubble size for Group A powders is of great significance for design. The single most important parameter controlling bubble size is... 

The most important parameter that affects the resistivity is the amount of carbon black particles, and of secondary importance is the type and especially the shape of the carbon black particles. The susceptibiUty of the carbon black to oxidation may possibly lead to high resistivity of insulation shields. The type of polymer used in a semiconducting material is also an important parameter that can affect resistivity. 

Monomer Reactivity. The poly(amic acid) groups are formed by nucleophilic substitution by an amino group at a carbonyl carbon of an anhydride group. Therefore, the electrophilicity of the dianhydride is expected to be one of the most important parameters used to determine the reaction rate. There is a close relationship between the reaction rates and the electron affinities, of dianhydrides (12). These were independendy deterrnined by polarography. Stmctures and electron affinities of various dianhydrides are shown in Table 1. 

Extension of the appHcations of polymethine dyes has required special spectral and other characteristics. As a rule, the search for and synthesis of promising new compounds having desired properties imply the preliminary estimation of their most important parameters on the basis of elaborated theoretical conceptions. Thus, an effective way of governing electron properties consists of the variation of molecular topology of polymethines. 

Sweeteners. The sweeteners (qv) used in carbonated beverages may be either nutritive or noimutritive. The quaUty of the sweetener is one of the most important parameters affecting the overall quaUty of the beverage. Organoleptic profile (taste and odor), solubiUty, microbial stabiUty, and temperature stabiUty are important quaUty parameters. 

Extruded Articles. In extmded article compounding, the most important parameters are scorch safety and flow characteristics (53). The bisphenol cure system again offers the best scorch resistance of the available fluorocarbon elastomer cure systems. Good flow characteristics can be achieved through proper selection of gum viscosities. Also, the addition of process aids to the formulation can enhance the flow characteristics. Typical formulations for extmsion grade fluorocarbon elastomers are given iu Table 7. 

The mean residence time T (defined as H JF) is the most important parameter, since it determines the time over which particles are exposed to grinding. Measurements on several industrial mills (Weller, Automation in Mining Mineral and Metal Processing, 3d IFAC Symposium, 303-309, 1980) (measured on the water, not the ore) showed that the maximum mill filhng was about 40 percent, and the maximum flow velocity through the mill is 40 m/h. 

One of the most important parameters of an immobilized-carrier complex is stability of its activity. Catalytic activity of the complex diminishes with time because of leakage, desorption, deactivation, and the like. The half-life of the complex is often used to describe the activity stabihty. Even though there may be frequent exceptions, hn-ear decay is often assumed in treating the kinetics of activity decay of an immobilized complex. 

High availability and reliability are the most important parameters in the design of a gas turbine. The availability of a power plant is the percent of time the plant is available to generate power in any given period. The reliability of the plant is the percentage of time between planed overhauls. 

The use of pyrometers in control of the advanced gas turbines is being investigated. Presently, all turbines are controlled based on gassifier turbine exit temperatures, or power turbine exit temperatures. By using the blade metal temperatures of the first section of the turbine the gas turbine is being controlled at its most important parameter, the temperature of the first stage nozzles and blades. In this manner, the turbine is being operated at its real maximum capability. 

If a life cycle analysis were conducted the new costs of a plant are about 7-10% of the life cycle costs. Maintenance costs are approximately 15-20% of the life cycle costs. Operating costs, which essentially consist of energy costs, make up the remainder, between 70-80% of the life cycle costs, of any major power plant. Thus, performance evaluation of the turbine is one of the most important parameter in the operation of a plant. 

An example of liquid/liquid mixing is emulsion polymerization, where droplet size can be the most important parameter influencing product quality. Particle size is determined by impeller tip speed. If coalescence is prevented and the system stability is satisfactory, this will determine the ultimate particle size. However, if the dispersion being produced in the mixer is used as an intermediate step to carry out a liquid/liquid extraction and the emulsion must be settled out again, a dynamic dispersion is produced. Maximum shear stress by the impeller then determines the average shear rate and the overall average particle size in the mixer. 

One of the most important parameters to measure is speed, yet it is often overlooked. The fan law in Chapter 5 states that for a centrifugal compressor, the head is proportional to speed squared. For an axial, the sensitivity to speed is as great or greater. Capacity is directly proportional to speed on all compressors, both the positive displacement and the... 

Among the most important parameters for materials characterization are the compositions of binary Gej Sij ) alloys, ternary Ai B C (e.g.,... 

The ratio PVC/CPVC (or reduced CPVC) is a simple but profound index of primer film structure that is perhaps the most important parameter in all of paint technology [70]. The relationship of the reduced CPVC to film structure can be appreciated by reference to Fig. 8. This figure shows a representation of a dry primer film with a range of pigment volume fraction that increases from left to right. 

The properties of gas ions are of great importance for the electrical performance of an electrostatic precipitator. They also are very important for particle-charging processes. The size of gas ions is normally such that they can be regarded as gas molecules carrying a single elementary charge. It can even be assumed that ions form a gas component with a very low- partial pressure. Thus, the thermal motion of gas ions is assumed to be similar to that of gas molecules. The most important parameters describing the properties of gas ions are... 

Collection efficiency is the single most important parameter in the performance of a filter. Based on typical operational efficiencies for various gas-... 

MWCNT grows only inside the cathode deposit and does not exist in other places in the reactor. Quantity of MWCNT obtained depends on the pressure of He atmosphere in the reactor, which is the most important parameter. The highest quantity of MWCNT is obtained when the pressure of He is ca. 500 Torr. When this value becomes below 100 Torr, almost no MWCNT grow. This contrasts to that the highest quantity of fullerene is obtained when the pressure becomes 100 Torr or less. 

This section first presents literature review on pressure vessel bursts and BLEVEs. Evaluation of energy from BLEVE explosions and pressure vessel bursts is emphasized because this value is the most important parameter in determining blast strength. Next, practical methods for estimating blast strength and duration are presented, followed by a discussion of the accuracy of each method. Example calculations are given in Chapter 9. 

Generally, optimizing the selectivity by choosing a gel medium of suitable pore size and pore size distribution is the single most important parameter. Examples of the effect of pore size on the separation of a protein mixture are given in Fig. 2.15. The gain in selectivity may then be traded for speed and/ or sample load. However, if the selectivity is limited, other parameters such as eluent velocity, column length, and sample load need to be optimized to yield the separation required. 

The pore size is the most important parameter that specifies the column used in HOPC. The pore size determines the boundary of MW in the segregation... 

Now, the most important parameter in the kinetics of any reaction is the rate of product formation. This rate is given by... 

One of the first examples of the application of reverse-phase liquid chromatography-gas chromatography for this type of analysis was applied to atrazine (98). This method used a loop-type interface. The mobile phase was the most important parameter because retention in the LC column must be sufficient (there must be a high percentage of water), although a low percentage of water is only possible when the loop-type interface is used to transfer the LC fraction. The authors solved this problem by using methanol/water (60 40) with 5% 1-propanol and a precolumn. The experimental conditions employed are shown in Table 13.2. 

There are many examples of increased corrosion at or near nozzles and jets and this is a recurring problem requiring frequent replacement and maintenance. The use of hydrodynamics and, in particular, dimensional group analysis, can show the most important parameters and can indicate the comparative rates of corrosion. 

The most important parameters of deposition are the temperature and the pH of the solution. Generally speaking, raising the temperature increases the rate of deposition. The solution can be alkaline or acid, the latter being preferred. The composition and operating conditions of a typical bath are ... 

In Section 1.1 corrosion was defined simply as the reaction of a metal with its environment, and it was emphasised that this term embraces a number of concepts of which the rate of attack per unit area of the metal surface, the extent of attack in relation to the thickness of the metal and its form (uniform, localised, intergranular, cracking, etc.) are the most significant. The rate of corrosion is obviously the most important parameter, and will determine the life of a given metal structure. Whether or not a given rate of corrosion can be tolerated will, of course, depend upon a variety of factors such as the thickness of the metal, the function and anticipated life of the metal structure and the effect of the corrosion products on the environment, etc. 

Since hydrofluoride synthesis is based on thermal treatment at relatively high temperatures, the possibility of obtaining certain fluorotantalates can be predicted according to thermal stability of the compounds. In the case of compounds whose crystal structure is made up of an octahedral complex of ions, the most important parameter is the anion-cation ratio. Therefore, it is very important to take in to account the ionic radius of the second cation in relation to the ionic radius of tantalum. Large cations, are not included in the... 

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