BET characteristic


The descriptor set can then be reduced by eliminating candidates that show such bad characteristics. Optimization techniques such as genetic algorithms (see Section 9.7) are powerful means of automating this selection process.  [c.490]

I got much advice and encouragement during my deliberations over moving to USC from Martin Kamen, a friend and true Renaissance man, as well as an outstanding seientist (co-discoverer of the carbon-14 isotope and a leading biological chemist). Martin was then attempting to build up the molecular biology program at USC. His plans never really worked out, but, characteristically, he looked at the broader picture and encouraged me. He also taught me that, this close to Hollywood, not everything is as it seems or as it is promised, and thus it is useful to have matters properly clarified and put into writing.  [c.111]

As the fluid flow rate is increased beyond the minimum fluidizing velocity, the bed expands. The total pressure drop across the bed remains essentially constant, but the pressure drop per unit height decreases as shown in Figure 1. At flow rates above the minimum for fluidization, bed characteristics depend greatly on whether the fluid is a liquid or a gas. For most liquid fluidized systems, the bed expands uniformly, with particles being well dispersed throughout. For most gas fluidized beds the gas flow in excess of minimum fluidization will pass up through the bed as bubbles. These bubbles have many of the properties of gas bubbles in liquids. The bubbles contain very few particles. Most particles remain in the "emulsion phase, packed closely together as they were at minimum fluidization conditions.  [c.29]

The specific cake resistance r(nr ) depends on particulate bed characteristics e and According to the Carman-Kozeny equation for packed beds (Chapter 2)  [c.91]

Another important class of dryer is the fluidized-bed dryers. Some designs combine spray and fluidized-bed dryers. Choice between dryers is usually based on practicalities such as the materials handling characteristics, product decomposition, product physical form (e.g., if a porous granular material is required), etc. Also, dryer efficiency can be used to compare the performance of different dryer designs. This is usually defined as follows -.  [c.91]

The problem with representing a reactor profile is that, unlike utility profiles, the reactor profile might involve several streams. The reactor profile involves not only streams such as those for indirect heat transfer shown in Fig. 13.1 but also the reactor feed and effluent streams, which can be an important feature of the reactor heating and cooling characteristics. The various streams associated with the reactor can be combined to form a grand composite curve for the reactor. This can then be matched against the grand composite curve for the rest of the process. The following example illustrates the approach.  [c.332]

The heat input to diyers is to a gas and as such takes place over a range of temperatures. Moreover, the gas is heated to a temperature higher than the boiling point of the liquid to be evaporated. The exhaust gases from the dryer will be at a lower temperature than the inlet, but again, the heat available in the exhaust will be available over a range of temperatures. The thermal characteristics of dryers tend to be design-specific and quite difierent in nature from both distillation and evaporation.  [c.359]

C, b.p. 170 C (decomp.), has a characteristic odour. It is the Diels-Alder product of cyclopentadiene reacting with itself, the exo-form being formed most rapidly but the endo-form is thermodynamically favoured. At temperatures above ISO C a retro-Diels-Alder reaction occurs and cyclopentadiene monomer is regenerated see diene reactions.  [c.135]

The criterion retained up to now in the specifications is not the true vapor pressure, but an associated value called the Reid vapor pressure, RVP. The procedure is to measure the relative pressure developed by the vapors from a sample of motor fuel put in a metallic cylinder at a temperature of 37.8°C. The variations characteristic of the standard method are around 15 millibar in repeatability and 25 millibar in reproducibility.  [c.189]

Another characteristic similar to A/ 100 is the Distribution Octane Number (DON) proposed by Mobil Corporation and described in ASTM 2886. The idea is to measure the heaviest fractions of the fuel at the inlet manifold to the CFR engine. For this method the CFR has a cooled separation chamber placed between the carburetor and the inlet manifold. Some of the less volatile components are separated and collected in the chamber. This procedure is probably the most realistic but less discriminating than that of the AJ 100 likewise, it is now only of historical interest.  [c.200]

In reality, the biending index of a compound varies according to its concentration and the nature of the product receiving it it is not, therefore, an intrinsic characteristic. In spite of this problem, refiners have long used the concept of blending index to predict and establish their refining flow sheets based on data drawn from their own experience. This approach is disappearing except in certain cases, for example, concerning the addition of oxygenates. In this manner, Table 5.11 gives estimated blending values for different alcohols and ethers when they are added in small quantities to an unleaded fuel close to the specifications for Eurosuper (RON 95, MON 85). Taking into account the diversity of situations encountered in regards to the composition of the receiving product stream, one does not retain a unique value for the blending value, but on the contrary, a margin for possible variation.  [c.203]

This fuel is used for the diesel engines in passenger cars and in utility vehicles ranging from light delivery vans to heavy trucks carrying 38 tons. Such diversity of application can complicate the search for quality criteria, but in each situation, it will be the most demanding type of application, very often as it would be, the private automobile that determines the fuel specifications. Note that other types of non-highway diesel engines —fishing boats, construction equipment, farm tractors, and large ships— use motor fuels distinctly different from diesel fuel such as marine diesel, home-heating oil, and heavy fuel oil. Certain characteristics specified or recommended for these products take into account that they are ultimately going to be used for a diesel-type of combustion.  [c.212]

The properties of straight run diesel fuels depend on both nature of the crude oil and selected distillation range. Thus the paraffinic crudes give cuts of satisfactory cetane number but poorer cold characteristics the opposite will be observed with naphthenic or aromatic crudes. The increasing demand for diesel fuel could lead the refiner to increase the distillation end point, but that will result in a deterioration of the cloud point. It is generally accepted that a weight gain in yield of 0.5% could increase the cloud point by 1°C. The compromise between quantity and quality is particularly difficult to reconcile.  [c.223]

Formulation of home-heating oil is done without difficulty by the refiner who, selecting from available middle distillates, sends the streams whose characteristics are incompatible with the final specifications of diesel fuel to the home-heating oil pool. Examples of these characteristics are the cetane number and cold behavior. The segregation of diesel fuel and home-heating oil was not always done in the past but is now increasingly necessary, especially in winter for distribution of very fluid diesel fuels having cloud points less than -5°C. Furthermore, future specifications imposing different sulfur contents for each product will accentuate their differences.  [c.235]

The high C/H ratio for heavy fuels and their high levels of contaminants such as sulfur, water, and sediment, tend to reduce their NHV which can reach as low as 40,000 kJ/kg by comparison to the 42,500 kJ/kg for a conventional home-heating oil. This characteristic is not found in the specifications, but it is a main factor in price negotiations for fuels in terms of cost per ton. Therefore it is subject to frequent verification.  [c.237]

This is the essential characteristic for every lubricant. The kinematic viscosity is most often measured by recording the time needed for the oil to flow down a calibrated capillary tube. The viscosity varies with the pressure but the influence of temperature is much greater it decreases rapidly with an increase in temperature and there is abundant literature concerning the equations and graphs relating these two parameters. One can cite in particular the ASTM D 341 standard.  [c.282]

The standards for classifications and characteristics. They look completely like specifications but they are not enforced by law. Instead of speaking about standards for characteristics, it is more common to talk about standards for specifications. In spite of its very general usage, this expression is unfortunate because it continues to foster confusion between standards and specifications.  [c.294]

For each category of petroleum products, either governmental or customs specifications or standards for characteristics generally exist, but sometimes there may be nothing but those conditions usually required in commercial contracts.  [c.297]

These specifications and characteristics are defined with references to standard test methods which the different parties to a contract should conduct for quality control. The tables that follow show specifically the standards that are applicable in France, but a more general table in Appendix 2 shows the main test methods commonly referenced in specifications.  [c.297]

There are no specifications, but there are two French standards grouping the characteristics of bitumen and cutbacks.  [c.312]

To apply the extraction of characteristics not on single images but on series images will give the Fig-Conception for the extraction of characteristics  [c.14]

This stage can be divided in two sub-stages. The first sub-stage incorporates the damage developed during the initial quasi-static loading of the specimen to reach the maximum stress level and then unloading to the mean stress. This procedure is carried out in order to measure the initial stiffness of the specimen. The second sub-stage, which consists the main part of stage I, begins as soon as the fatigue amplitude is applied over the mean stress. This stage is characterised by the development of homogeneous non interactive damage, restricted to individual plies. Matrix cracking of the off-axis plies is the dominant damage mechanism. This mechanism continues being active until the Characteristic Damage State (CDS) is reached in all the off-axis plies. Small edge delaminations are also observed but these are limited and present only at the tips of the matrix cracks. Damage in this stage develops at a decreasing rate (Figure 6). This is due to the exhaustion of new damage sites and the slow growth of the existing ones.  [c.49]

Knowledge of authors with the acoustic emission technique utilisation at tests on contact loaded surfaces are discussed in the article. Experiment arrangement, test centre, measuring equipment itself are described. On examples of experimental measured results are explained advantages of AE signals detection in dependence on time. There are defined AE signal characteristic courses in relationship to contact fatigue properties of the tested surface. The results proved the acoustic emission technique enables reliable recognition of running-in period, stabilised run and very exact definition of origin stage of surface damaging, leading to the pitting. It is proposed direction of AE analysers utilisation not only in research area, but the acoustic emission technique may be successfully used even in industrial practice.  [c.59]

The destructive test has showed that the carbon plastic under the loading has the diffused characteristic of the deformation damage. But, simultaneously with the plural cracking of the comiector and fibre, stratification on the border filler-connector , the continuous development of one or several dominating defects up to the critical size, and initiation of the material destmction, is taking place. Therefore, the AE at the deformation process in the carbon plastic can be presented by two components acoustic emission (AEl), caused by the accumulation process of the disperse damage, and acoustic emission (AE2) of the dominating defect development. The parameters of the acoustic emission AE2 are in connection with the breaking point (5b, they are identifying the breaking point of the material.  [c.84]

For the magnetic linkage increase the power and high-voltage eoils are placed on the system rods The insulation gaskets are laid between the rods and the control yokes. Their thickness was determined due to the following reasons the magnetic linkage is increased in case of the gasket thickness reduction, but the anode voltage curve form is worsened in ease of the gasket thickness increase, the eurve form is improved, but the circuit load characteristic becomes more "soft".  [c.431]

Heat carriers. If adiabatic operation produces an unacceptable rise or fall in temperature, then the option discussed in Chap. 2 is to introduce a heat carrier. The operation is still adiabatic, but an inert material is introduced with the reactor feed as a heat carrier. The heat integration characteristics are as before. The reactor feed is a cold stream and the reactor efiluent a hot stream. The heat carrier serves to increase the heat capacity fiow rate of both streams.  [c.325]

A characteristic of a crystal is that the atoms, molecules or ions are arranged in a regular way in three dimensions (a lattice). It follows that if we start from an arbitrary origin in the crystal and proceed in any direction we shall arrive, after travelling a certain distance, at a point with the same environment as the point of origin. We may perform this process in two other directions and find the corresponding repeat distances . These three axes of reference, X, y and r, and the three repeat distances, , 6 and c, define a parallelopiped, defined by the symmetry elements but generally including the smallest volume, which contains a representative portion of the crystal structure, and which if indefinitely repeated in those directions will reproduce the crystal. A characteristic parallelopiped is termed the unit cell, and the repeat distances or cell dimensions (the sides of the unit cell) are written a, b and c, corresponding to the x, y and z axes. The angles between the axes taken in pairs, are called a, and y (between yz, zx and xy respectively). The choice of axes in the crystal is not completely arbitrary, except in the triclinic system, but is determined by the positions of the symmetry elements. The shape of the unit cell, and hence the constants required to define it, depends on the symmetry of the crystal, and the following table summarizes the data required in the various systems  [c.117]

CH3CH2)20. Colourless liquid with a pleasant, characteristic odour very volatile, its vapour forms an explosive mixture with air b.p. 34-5 C. It is manufactured by passing ethanol vapour into a mixture of 92 % ethanol and 78% sulphuric acid at J28 C. May also be produced as a by-product in the manufacture of alcohol from ethene. Commercial ether usually contains small amounts of water, ethanol, ethanal and the explosive peroxide. It is a comparatively inert compound and is an excellent solvent for a great many organic substances. Oxidized by nitric acid to ethanoic acid. Reacts with strong sulphuric acid to give ethyl hydrogen sulphate and with hydrogen iodide to give ethyl iodide. Chlorine reacts violently with ether at ordinary temperatures but forms various chloro-ethers at low temperatures. Crystalline co-ordination compounds are formed with some metallic salts. Can be employed for the production of general anaesthesia by inhalation and is generally a safe anaesthetic but it must be pure. Ether acts as a carminative to the stomach, and is administered in the form of spirit of ether as a restorative in collapse. It is also injected hypodermically for the same purpose. Medical and pharmaceutical uses account for a relatively small proportion of ether consumption, and it  [c.165]

CsHflOj. Colourless liquid, m.p. - 8-6""C, b.p. 223 "C. Exists in an almost pure state in the essential oils of wintergreen and sweet birch, but is mostly prepared by esterifying salicylic acid. It has a pleasant characteristic odour and is readily absorbed through the skin. It is used in perfumery and as a flavouring agent in food, drinks, dentifrices and cosmetics. It has the general medicinal properties of the salicylates, and is applied either alone or with other analgesics for easing the pain of lumbago, rheumatism and sciatica.  [c.261]

The cetane number of heavy fuels is generally between 30 and 40, but its determination is inexact considering the difficulties encountered when testing such products in a CFR engine. One possible way to operate is to dilute the fuel with diesel fuel or home-heating oil and estimate a blending index. There are also formulas to predict the auto-ignition qualities of heavy fuels using their physical characteristics (Fiskaa et al., 1985). We cite as an example the relation giving the CCAl (Calcuiated Carbon Aromaticity Index)  [c.240]

Sulphur and its products are the most common impurity in crude oil, ranging from 0.2% to over 6% in some Mexican and Middle Eastern crudes, with an average of 0.65% by weight. Corrosive sulphur compounds include free sulphur, hydrogen sulphide (FIjS, which is also highly toxic), and mercaptans of low molecular weight (e.g. ethyl mercaptan, CjFIjSFI). Mercaptans are formed during the distillation of crude oil, and require special alloys in plant equipment to avoid severe corrosion. The non-corrosive sulphur compounds are the sulphides (e.g. diethyl sulphide (C2FI5)2S), which are not directly corrosive, but require careful temperature control during processing to avoid decomposition to the corrosive products. Sulphur compounds have a characteristic bad smell, and both corrosive and non-corrosive forms are generally undesirable in crude oils.  [c.93]

Although wavelets provide powerful possibilities in signal processing, they are established as a common method only for a few years. The emphasis in their nowadays application is the field of data compression closely related to data denoising. We isolate features for flaw description proceeding from the denoising characteristics of the discrete wavelet transform. The wavelet transform has its roots in the Fast Fourier Transform. While the FFT decomposes the original signal in its frequency components, the Wavelet transform perform a multi-scaling analysis of the signal ([1] and [4]). From this representation one can denoise the image by a simple thresholding procedure. This is applied to the ROIs of the original image as well as to the ROIs extracted from the FFT filtered image. The ROIs are denoised with the two dimensional wavelet transform but they are exploited only in y-direction (the direction perpendicular to the crack). Two examples of denoised ROIs are shown in figure 6.  [c.463]

It is possible an appearance of such states for ferromagnetic materials which differ from an usual presentation as domains with a magnetization equals to magnetization of saturation. Such states may appear in anisotropic ferromagnetic materials under some special conditions of magnetization by permanent or remagnetization by alternative magnetic field. In such a cases a distribution of magnetization has an inhomogeneous character. Previously, it was found that they represent a field configurations which correspond to topologically nontrivial distributions only. But now a new conditions for appearance of distributions which correspond to coupled states of topologically non-trivial distributions of magnetization have been obtained. A presence of complex topological relief for distribution of magnetization in material is a characteristic feature of such states.  [c.653]


See pages that mention the term BET characteristic : [c.979]    [c.15]    [c.280]    [c.11]    [c.19]    [c.20]    [c.28]    [c.30]    [c.50]    [c.55]    [c.83]    [c.110]    [c.163]    [c.182]    [c.222]    [c.112]    [c.174]   
Physical chemistry of surfaces (0) -- [ c.631 ]