Saccharin methylation

The SCREEN model uses free format to read the numerical input data, with the exception of the exit velocity/flow rate option. The default choice for this input is stack gas exit velocity, which SCREEN will read as free format. However, if the user precedes the input with the characters VF= in columns 1-3, then SCREEN will interpret the input as flow rate in actual cubic feet per minute (ACFM). Alternatively, if the user inputs the characters VM= in columns 1-3, then SCREEN will interpret the  [c.301]

The sidebar discussion presents the order of regulatory options within the SCREEN model for point sources.  [c.302]

Thus, the user can input the minimum site boundary distance as the minimum distance for calculation and obtain a concentration estimate at the site boundary and beyond, while ignoring distances less than the site boundary. If the automated distance array is used, then the SCREEN model will use an iteration routine to determine the maximum value and associated distance to the nearest meter. If the minimum and maximum distances entered do not encompass the true maximum concentration, then the maximum value calculated by SCREEN may not be the true maximum. Therefore, it is recommended that the maximum distance be set sufficiently large initially to ensure that the maximum concentration is found. This distance will depend on the source, and some trial and error may be necessary however, the user can input a distance of 50,000 m to examine the entire array. The iteration routine stops after 50 iterations and prints out a message if the maximum is not found. Also, since there may be several local maxima in the concentration distribution associated with different wind speeds, it is possible that SCREEN will not identify the overall maximum in its iteration. This is not likely to be a frequent occurrence, but will be more likely for stability classes C and D due to the larger number of wind speeds examined.  [c.306]


The SCREEN model calculates plume rise for flares based on an effective buoyancy flux parameter. An ambient temperature of 293° K is assumed in this calculation and therefore none is input by the user. It is assumed that 55 percent of the total heat is lost due to radiation.  [c.309]

Since the concentration at a particular distance downwind from a rectangular area is dependent on the orientation of the area relative to the wind direction, the SCREEN model provides the user with two options for treating wind direction. The first option, which should be used for most applications of SCREEN and is the regulatory default, is for the model to search through a range of wind directions to find the maximum concentration.  [c.311]

The range of directions used in the search is determined from a set of look-up tables based on the aspect ratio of the area source, the stability category, and the downwind distance. The SCREEN model also provides the user an option to specify a wind direction orientation relative to the long axis of the rectangular area. The second option may be used to estimate the concentration at a particular receptor location relative to the area. The output table for area sources includes the wind direction associated with the maximum concentration at each distance.  [c.311]

The user must determine the initial dimensions of the volume source plume before exercising the SCREEN model volume source. Table 3 provides guidance on determining these inputs.  [c.312]


Many of the techniques used in the SCREEN model are based on assumptions and methods common to other EPA dispersion models. SCREEN uses a Gaussian plume model that incorporates source-related factors and meteorological factors to estimate pollutant concentration from continuous sources. It is assumed that the pollutant does not undergo any chemical reactions, and that no other removal processes, such as wet or dry deposition, act on the plume during its transport from the source. The basic Gaussian model equations and the interactions of the source-related and meteorological factors were discussed earlier. The basic equation for determining ground-level concentrations under the plume centerline is  [c.313]

Wake Region - Wake effects are divided into two regions, one referred to as the "near wake" extending from 3L to lOL (L is the lesser of the building height, h, and maximum projected width), and the other as the "far wake" for distances greater than lOL,. For the SCREEN model, the maximum projected width is calculated from the input minimum and maximum horizontal dimensions as (L + W ) . Unlike the cavity calculation, the comparison of plume height (due to momentum rise at two building heights) to wake height to determine if wake effects apply does not include stack tip downwash.  [c.319]

As noted earlier, the SCREEN model also contains the option to calculate maximum 24-hour concentrations for terrain elevations above stack height. A final plume height and distance to final rise are calculated based on the VALLEY model screening technique (Burt, 1977) assuming conditions of F stability (E for urban) and a stack height wind speed of 2.5 m/s. Stack tip downwash is incorporated in the plume rise calculation. The user then inputs a terrain height and a distance (m) for the nearest terrain feature likely to experience plume impaction, taking into account complex terrain closer than the distance to final rise. If the plume height is at or below the terrain height for the distance entered, then SCREEN will make a 24-hour average concentration estimate using the VALLEY screening technique devised by EPA.  [c.322]

Erode, R.W., 1991. A Comparison of SCREEN Model Dispersion Estimates with Estimates From a Refined Dispersion Model. Seventh Joint Conference on Applications of Air Pollution Meteorology with A WMA, 93-96.  [c.343]

EPA. 1995. SCREEN Model User s Guide. U.S. Environmental Protection Agency, Washington, D.C.  [c.598]

There are several important partial results. (1) Definition of quality of the CT-data in relation to the imaging task, including a model of the X-ray paths and how it is used to predict the optimal performance. (2) A model and method to determine how the information of the imaged object transfer from the detector entrance screen through the detector chain to CT  [c.208]

The theoretical model of the CT-data collection process is shown schematically in figure 5. The X-ray spectrum generated in the X-ray source is shown to the left. Spectra for the actual X-ray source were measured with high accuracy with a Compton spectrometer [4, 5]. The spectrum chosen is pre-shaped with filters and then divided into three paths. Sj penetrates the object beside the defect, S2 penetrates both object and defect, and So passes beside the object. The X-ray spectrum will be filtered differently along each path, that is, both by number of photons and change of energy distribution. The expectation value for the energy imparted to the detector screen at each path, Ei(e) where i=0-2, is a product of the expectation value for the number of photons in each spectra, Ei(N), and the expectation value of the single event distribution, Ei(e ). The single event distributions for paths S0.2 in the middle in the figure represent the detector screen simulated with Monte Carlo technique [6].  [c.210]

Conventional eddy current probes induce eddy currents in the material parallel to the surface. Corrosion forces these currents to seek different paths, resulting in a change in their magnetic fields and hence a change in the impedance of an absolute sensing or receiving coil. This impedance change, shown on the screen of an eddy current instrument, is primarily an indication of the average volumetric metal loss.  [c.283]

Due to the better sensitivity of IP-ND and IP the neutron exposure times could be reduced for a factor about 125 in comparison with the Gd screen/radiographic SR film method. In the later technique neutron exposure time of more than 90 min in the thermal neutron flux of 4.5 10 n cm s are required, while for the obtaining a neutron image of comparable quality using IP-ND the exposure time could reduced to only 10-40 seconds In Fig. 1 NR images of a Incite step wedge, Fe step wedge and BPI and SI neutron standard objects obtained with an IP-ND at neutron fluence of about 1.13 lO cm (Fig. la) and 5.6 10 cm (Fig. lb) are presented. The corresponding values of the recorded signal of the free neutron beam are 655 PSL/mm and only 26 6 PSL/mm . respectively. Both images are underexposed for factor of about 1.5 and 38 respectively. However, the image on Fig. la clearly reveals all three holes in the first 6 steps of the Fe wedge. The thickness of steps varies from 1-9 as 3 mm, 2 mm, 1.5 mm, 1.0 mm, 0.57 mm, 0.5 mm, 0.375 mm, 0.25 mm and 0.125 mm respectively. In the step 7 only 2T and 4T holes (T=step thickness, corresponding hole diameters 0.7 mm and 1.5 mm respectively) and in the step 8 the hole 4T are visible. Ail steps in the Incite calibration wedge can be resolved. Here the film neutron radiograph using single coated fine grained radiographic film and Gd metal screen obtained at neutron fluence of about 2 10 cm reveals also the holes 2T and 4T in the step 8. The NR image obtained with IP-ND at neutron fluence of only 5.6 10 cm still reveals all 3 holes in the first 4 steps and first 6 steps in the Incite wedge. The images of BPI and SI neutron standards can still be used for the neutron beam quality evaluation. The neutron image at so low fluence is rather noisy, however it demonstrates the feasibility of direct NR even with extremely weak neutron sources.  [c.508]

During x-raying of sample on PM-1 and PO-2 film types there was chosen optimal thickness for metal amplifying screens according to maximal film blackening at minimal exposure for eaeh concrete case. Also the amplifying screen thickness change and thickness growth of material layer examined with x-rays were researched. Owing to radiation filtration during the pass through the material layer optimal thiekness of front amplifying screen layer correspondingly increases. High intensity of radiation allows to short significantly exposure  [c.513]

With the reference block method the distance law of a model reflector is established experimentally prior to each ultrasonic test. The reference reflectors, mostly bore holes, are drilled into the reference block at different distances, e.g. ASME block. Prior to the test, the reference reflectors are scanned, and their maximised echo amplitudes are marked on the screen of the flaw detector. Finally all amplitude points are connected by a curve. This Distance Amplitude Curve (DAC) serves as the registration level and exactly shows the amplitude-over-distance behaviour" of the reference reflector for the probe in use. Also the individual characteristics of the material are automatically considered. However, this curve may only be applied for defect evaluation, in case the reference block and the test object are made of the same material and have undergone the same heat treatment. As with the DGS-Method, the value of any defect evaluation does not consider the shape and orientation of the defect. The reference block method is safe and easy to apply, and the operator need not to have a deep understanding about the theory of distance laws.  [c.813]

The basic device is very simple. A tip of refractory metal, such as tungsten, is electrically heat-polished to yield a nearly hemispherical end of about 10" cm radius. A potential of about 10 kV is applied between the tip and a hemispherical fluorescent screen. The field, F, falls off with distance as kr, and if the two radii of curvature are a and b, the total potential difference V is then  [c.299]

If 1 /b is neglected in comparison to 1 /a, then k-aV and the field at the tip F a) - V/a or 10 V/cm in the present example. This very high value, equivalent to 100 V/nm, is sufficient to pull electrons from the metal, and these now accelerate along radial lines to hit the fluorescent screen. Individual atoms serve as emitting centers, and different crystal faces emit with different intensities, depending on the packing density and work function. Since the magnification factor b/a is enormous (about 10 ), it might be imagined that individual atoms could be seen, but the resolution is limited by the kinetic energy of the electrons in the metal at right angles to the emission line and obtainable resolutions are about 3-5 nm. Nevertheless, the technique produces miraculous pictures showing the various crystal planes that form the tip in patterns of light and dark. Adsorbates, such as Ni, may increase the emission intensity providing a means to follow the surface migration of adsorbed species.  [c.299]

You can rotate a model (m this case just an sp C) move it around the screen and change its size using the mouse m conjunction with the keyboard (see the follow mg table) Try these operations now  [c.1259]

Rotation and translation affect only the active model but scaling affects all mod els on the screen  [c.1264]

To begin the process, the particulate raw materials are rough-screened to remove oversize materials. The oversize materials may be used as fuel or processed through a grinder and returned to the screen. Also, there should be a unit in this area to remove rocks and trash metal. The material then moves to the milling/drying/screening area (material preparation area). It should be noted that from this point to the mat-formers, materials usually flow in two streams, one of smaller particles for the surfaces of the board and one of larger particles for the core or middle of the board. Milling generally precedes drying because a better mix of particle sizes is achieved if material is milled when still wet or moist. However, dry milling requires less power and some manufacturers prefer this sequence, even though more fines (small particles) are generated. If dry planer shavings are part of the mix, they will necessarily be milled dry. Another advantage of drying preceding milling is that it allows for separation of grit (dirt, sand, etc) following drying, which reduces wear on grinding equipment and also reduces the chance of fires occurring during milling. Grit removal is not easily done on wet or moist particles. Particulate milling is done by hammermills, impact mills, refiners with special plates, or knife-ring flakers. The knife-ring flaker is a machine designed to make flakes (long, thin, flat particles) from larger residues, such as chips. The other forms of mills use attrition or impact to break up the particles, and a much smaller mix of particles is generally obtained. In a few cases where small logs are used as raw material, these are first debarked and then flaked in large dmm or disk flakers. The bark is usually used as fuel.  [c.391]

At this point, the dry particles and flakes may pass through a system designed to remove grit. To avoid excessive wear on saws and milling machinery downline and especially for the sake of safeguarding customers equipment, it is necessary to have a grit (siUca) level less than 0.05%, and preferably less than 0.03%. In these days, when more emphasis is being placed on recycling of urban waste woods, grit and metal removal equipment is a necessity for those mills reusing this resource. If the grit is primarily very fine material, it can be removed by a small screen with only small wood losses, and these can be used for fuel. If larger grit is present, more sophisticated equipment is required.  [c.391]

Acryhc stmctural adhesives have been modified by elastomers in order to obtain a phase-separated, toughened system. A significant contribution in this technology has been made in which acryhc adhesives were modified by the addition of chlorosulfonated polyethylene to obtain a phase-separated stmctural adhesive (11). Such adhesives also contain methyl methacrylate, glacial methacrylic acid, and cross-linkers such as ethylene glycol dimethacrylate [97-90-5]. The polymerization initiation system, which includes cumene hydroperoxide, N,1S7-dimethyl- -toluidine, and saccharin, can be apphed to the adherend surface as a primer, or it can be formulated as the second part of a two-part adhesive. Modification of cyanoacrylates using elastomers has also been attempted copolymers of acrylonitrile, butadiene, and styrene ethylene copolymers with methylacrylate or copolymers of methacrylates with butadiene and styrene have been used. However, because of the extreme reactivity of the monomer, modification of cyanoacrylate adhesives is very difficult and material purity is essential in order to be able to modify the cyanoacrylate without causing premature reaction.  [c.233]

Metallisation of the green sheets is usually carried out by screen printing, whereby a suitable metal ink consisting of metal powders dispersed in resin and solvent vehicles is forced through a patterned screen. Palladium [7440-05-3] and silver—palladium (Ag Pd) alloys are the most common form of metallisation tungsten [7440-33-7] and molybdenum [7439-98-7] are used for high (>1500° C) temperature MFCs (47—52). Following screening, the metallised layers are stacked and laminated to register (align) and fuse the green sheets into a monolithic component. Proper registration is cmcial to achieve and maintain capacitance design (MLC capacitors) and for proper via-hole placement in MLC packages.  [c.313]

Thick film compositions possess three parts (/) functional phase, (2) binder, and (J) vehicle. The functional phase includes various metal powders for conductors, electronic ceramics for resistors, and dielectrics for both capacitors and insulation. Examples of typical components for thick film compositions are given in Table 4. The binder phase, usually a low (<1000° C) melting glass adheres the fired film to the substrate whereas the fluid vehicle serves to temporarily hold the unfired film together and provide proper rheological behavior during screen printing. Thick film processing for hybrid integrated circuits typically takes place below 1000°C providing flexible circuit designs.  [c.313]

The beater additive process starts with a very dilute aqueous slurry of fibrous nitrocellulose, kraft process woodpulp, and a stabilizer such as diphenylamine in a felting tank. A solution of resin such as poly(vinyl acetate) is added to the slurry of these components. The next step, felting, involves use of a fine metal screen in the shape of the inner dimensions of the final molded part. The screen is lowered into the slurry. A vacuum is appHed which causes the fibrous materials to be deposited on the form. The form is pulled out after a required thickness of felt is deposited, and the wet, low density felt removed from the form. The felt is then molded in a matched metal mold by the appHcation of heat and pressure which serves to remove moisture, set the resin, and press the fibers into near final shape (180—182).  [c.53]

Deposition from Liquid Gold. Liquid gold refers either to organic suspensions or emulsions containing finely divided gold powder or to solutions of organogold compounds in organic solvents. Liquid golds are formulated as paints or inks which are appHed by painting, bmshing, screen printing, etc, and that yield weU-bonded gold films after subsequent drying and firing. The thickness of films derived from dispersed metal is ca 25 p.m. The thickness of films derived from organogold compounds ranges from (5-20) x 10 //m.  [c.385]

As noted, the SCREEN model is written as an interactive program for the PC. Therefore, SCREEN is normally executed by simply typing SCREEN from any drive and directory that contains the SCREEN3.EXE file, and responding to the prompts provided by the program. However, a mechanism has been provided to accommodate the fact that for some applications of SCREEN the user might want to perform several runs for the same source  [c.299]

The SCREEN model will then read the responses to its prompts from the EXAMPLE.DAT file rather than from the keyboard. The output from this run will be stored in a file called SCREEN, which can then be compared with the EXAMPLE.OUT file provided on the program. The file containing the redirected input data may be given any valid DOS pathname. To facilitate the creation of the input file for the SCREEN model, SCREEN has been programmed to write out all inputs provided to a file called SCREEN.DAT during execution. Therefore, at the completion of a run, if the user types the following, the last run will be exactly duplicated  [c.300]

The use of the methods of Briggs to estimate plume rise are relied on in the SCREEN model. Stack tip downwash is estimated following Briggs (1973, p.4) for all sources except those employing the Schulman-Scire downwash algorithm. Buoyancy flux for non-flare point sources is calculated from  [c.316]

The X-ray TV introscope (XTVI) developed in Introscopy Institute in accordance with [1] enables to detect with high resolution pores, cavities, metal and nonmetal inclusions, poor fusions in welded joints and cracks, whose opening plane coincides with X-raying direction. It can also be used to identify geometries of internal details, to detect foreign inclusions, discontinuities, external defects, inaccessible for external inspection, like cuts, bums -through, etc. Introscope operation principle is based on exposure of objects to X-radiation, conversion of a latent X-ray image into a TV signal with subsequent computer processing and image visualization on a monitor screen.  [c.449]

If you are running an updated version (V 8.0) of PC Model, click on force fields mm3. Omit this step for older versions. Click on Analyze (or compute depending on the version of PCMODEL) to obtain a menu of options. Select minimize. The geometry changes can be seen on the screen and a sequence of numbers appears in the right panel of the CRT screen, ending in Hf, the enthalpy of formation. This is the PCMODEL-MM3 calculated value of for cis-2-  [c.149]

Use Learning By Modeling to make a molecular model of ethane The staggered conformation will appear by default Verify that the torsion (dihe dral) angles are 60° Convert the staggered to the eclipsed conformation by adjust mg the dihedral angles Rotate the models on the screen so that they correspond to the orientations shown for the wedge and dash sawhorse and Newman pro ection drawings shown in Figures 3 2 and 3 3  [c.106]

Fibrillated Fibers. Instead of extmding cellulose acetate into a continuous fiber, discrete, pulp-like agglomerates of fine, individual fibrils, called fibrets or fibrids, can be produced by rapid precipitation with an attenuating coagulation fluid. The individual fibers have diameters of 0.5 to 5.0 ]lni and lengths of 20 to 200 )Jm (Fig. 10). The surface area of the fibrillated fibers are about 20 m /g, about 60—80 times that of standard textile fibers. These materials are very hydrophilic an 85% moisture content has the appearance of a dry soHd (72). One appHcation is in a paper stmcture where their fine fiber size and branched stmcture allows mechanical entrapment of small particles. The fibers can also be loaded with particles to enhance some desired performance such as enhanced opacity for papers. When filled with metal particles it was suggested they be used as a radar screen in aerial warfare (73).  [c.297]

Ceramic-grade fluorspar and acid-grade fluorspar have the typical analyses shown ia Table 6. Both types are usually finely ground, the bulk of the powder passing a 0.23 mm (65 mesh) screen, and 22 to 81% held on a 44 p.m (325 mesh) screen. Optical-grade calcium fluoride, for special glasses and for growing single crystals, is suppHed in purities up to 99.99% Cap2. This grade is especially low in transition elements. For process control (qv) and product specification, fluorspar is commonly analy2ed for fluorine, calcium, siUca, carbonate, sulfide, iron, barium, and where significant, for metal values.  [c.174]

See pages that mention the term Saccharin methylation : [c.299]    [c.305]    [c.509]    [c.26]    [c.661]    [c.428]    [c.82]    [c.824]    [c.428]    [c.168]    [c.396]    [c.498]   
Advances in heterocyclic chemistry Vol.2 (1963) -- [ c.255 , c.266 , c.267 ]