bluuebunny/crossref_metadata_2025 huggingface dataset:
Infrared Spectroscopy in Analysis of Polymer Structure–Property Relationships
Authors: Pennington Brian D.
Published: September 2006

Infrared (IR) spectroscopy is the measurement of the intensity of IR radiation absorbed at specific wavelengths, which can be used for the characterization of solid, liquid, gas, fiber, and powder samples. This technique allows molecular level identification of surface, interfacial, and bulk regions owing to its high selectivity and sensitivity. Quantitative measurement of molecular functionalities is accomplished by comparison with standards of known concentrations. The IR spectroscopic methods covered in this article include transmission, internal reflectance, reflection–absorption, diffuse reflectance, photoacoustic (PA), and step‐scan techniques. Common applications of IR spectroscopy include polymer blending, adhesion, surface analysis, kinetics, and multidimensional studies.

The molecular specific information IR spectroscopy provides is one of the most useful aspects of this technique when compared to other common analytical methods. Compared with gas chromatography/mass spectrometry (GC/MS) which reaches parts per billion detection limits, IR spectroscopy, which is much less sensitive, provides nondestructive analysis. The depth resolution of X‐ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) is several orders of magnitude better than IR spectroscopy, yet the ultrahigh vacuum (UHV) operating conditions of these techniques would destroy volatile samples. While the lateral resolution of scanning electron microscopy (SEM), energy‐dispersive X‐ray analysis (EDX), and transmission electron microscopy (TEM) techniques is superior to IR spectroscopy, these methods require tedious sample preparation. IR spectroscopy offers sensitivity to a wide range of samples with limited sample preparation needed.
Infrared Spectroscopy in Analysis of Polymers and Rubbers
Authors: Chalmers John M.
Published: September 2006

The infrared spectrum of a polymer or rubber is a profile of its absorption characteristics plotted against infrared wavenumber (or frequency). It is generated when infrared radiation interacts with the molecular moieties that constitute the polymer or rubber material. It is a distinctive property (a “fingerprint”) of the polymer or rubber sample in the form, manner and environment in which it is being examined. It is based on the absorption of infrared radiation at frequencies that match those of the normal modes of vibration within the macromolecule. These absorption features are characteristic of the molecular configuration, sequencing and conformation, and state of order. Absorptions by internal vibrations predominate in the mid‐infrared region (ca. 4000–400 cm
−1
); they involve a few selected atoms in a molecular (functional) grouping, which is a sub‐set of those constituting the macromolecule. External vibrations, such as lattice vibrations, which involve segments of macromolecules in crystalline regions, tend to occur at low wavenumbers (<400 cm
−1
). The intensity of an absorption band is, to a first approximation, proportional to the number density of vibrating species giving rise to that band. The intensity of an absorption band is related to the dipole moment change associated with the molecular vibration; if it is large then the band intensity will be high. Infrared spectroscopy is highly specific. For some quantitative analyses, it can be very precise and sensitive (<0.1%). It is complemented with Raman spectroscopy, for which the selection rules are different and relate band intensity to the change of polarizability occurring during a molecular vibration. Infrared spectroscopy can be used to identify and analyse the molecular structure, composition, order and morphology, both qualitatively and quantitatively, of polymers, copolymers and rubbers and their products. However, for heavily filled and plasticized formulations the spectral interferences may be too high to allow direct or adequate interpretation of a spectrum, and separation of the components will be necessary for unambiguous identifications.
Mechanical Properties of Polymers and Rubbers
Authors: Gao Zhanjun (Justin)
Published: September 2006

One major focus of this article is on models and testing techniques that can be applied readily to the research and development of polymers and rubbers. The article is divided into five sections, with the introduction being the first section. Sections 2 and 3 deal with stress–strain relationships and time‐ and temperature‐dependent behavior. The linear Hooke's law is described first, followed by the molecular mechanism of rubber elasticity, the Mooney–Rivlin model, and the Ogden model. Three viscoelastic models are presented, together with the Boltzmann superposition principle. Various types of apparatus for viscoelastic property measurements are described. The Williams–Landel–Ferry (WLF) equation for time–temperature superposition is illustrated with experimental data.

Section 4 covers the ultimate properties. Topics include: cold drawing in crystalline polymers; temperature and pressure effects on yield stress; brittle–ductile transition; crazing; fracture; tearing of rubbers: extension of Griffith theory; viscoelastic rupture of elastomers; fatigue; and the effects of molecular weight and crystallinity. The ultimate properties are more complex and less well understood. Emphasis is placed on the most important aspects and techniques for understanding and representing yielding and fracture.

Section 5 is devoted to polymer blends and composites. Rubber‐toughened polymers are used to discuss the enhancement of the deformation mechanisms in polymers. A general, mechanistic model is then presented to determine the moduli, break strengths, and break strains for polymer films containing liquid and solid microfillers.
Near‐Infrared Spectroscopy of Polymers and Rubbers
Authors: Workman Jerry J.
Published: September 2006

Molecular spectroscopy as provided using the near‐infrared (NIR) measurement technique is valuable for polymer identification, characterization, and quantitation. NIR spectroscopy can be completed for in situ process applications where no sample preparation is required, and where rugged optical systems are a necessity. The NIR region is a complimentary band of the electromagnetic spectrum to the mid‐infrared (MIR) region (4000–500 cm−1), encompassing 13 333–4000 cm−1or 750–2500 nm (nanometers, 10−9 m).

NIR and infrared (IR) spectroscopy are routinely used to qualify monomers prior to polymerization reactions. NIR is used to measure the kinetics of polymer onset and can be used to detect end‐point completion and initiator compound levels in polymerization reactions. NIR spectroscopy can also be used to sort polymers and to control the quality of incoming raw monomers and finished polymeric materials. Molecular spectroscopy using the NIR and IR measurement techniques is often used for competitive analysis and to determine thermal or photoinduced oxidation or degradation reactions in polymers. This article delineates the background, theory, band assignments, and applications of NIR spectroscopy for the measurement of polymers and rubbers.
Nuclear Magnetic Resonance, Imaging of Polymers
Authors: Hafner Siegfried
Published: September 2006

Nuclear magnetic resonance (NMR) imaging is a non‐invasive technique which is based on the phenomenon of NMR. The resonance frequencies of the nuclear spins can be made spatially dependent by introducing a magnetic field gradient into the NMR experiment. The acquired NMR signal is thus spatially encoded and a spin‐density image of the sample can be reconstructed.

While originally developed for medical applications, NMR imaging is now increasingly applied for materials investigations. The main advantages of the technique are its nondestructivity, which allows processes to be investigated in situ, and the possibility of introducing NMR spectroscopic information and relaxation contrast into the NMR images. Limitations, on the other hand, are the relatively low sensitivity and the broad NMR lines of polymers, both of which limit the spatial resolution. Whereas the latter can be dealt with by suitable methods, the sensitivity ultimately restricts the achievable spatial resolution of conventional NMR imaging techniques to about 10µm3. NMR imaging therefore must not be considered as a competitor of other microscopic techniques such as electron microscopy but as a characterization technique that provides supplementary information. Examples illustrating all these aspects are given in this article.
Surface Energetics of Polymers and Rubbers, Characterization of
Authors: Eley Richard R. , Petrash Stanislaw
Published: September 2006

Adhesion of polymeric materials to various substrates, from metals to glass to other polymers, is a subject that continues to grow in importance, with today's technologies. The biocompatibility of polymer‐based implantable devices and prostheses is largely determined by the tendency of the material surfaces to be ‘wetted’ or adhered to by proteins. Surface and interfacial energy relationships determine in large part whether the adhesive and adherend achieve the intimacy of molecular contact that is a requisite for good adhesion. An aspect of the behavior of polymer blends and of block copolymers is that, depending on the relative surface energy of the components, and on the phase morphology and chain mobility, lower energy components may segregate to the surface to the detriment of interfacial adhesion, or perhaps promoting heterophase nucleation. There are numerous both technological and scientific motivations for the characterization of polymer surface energy.

The objective in surface energy measurement is to characterize the free energy of a solid or a liquid surface (or, in general, an interface). The surface free energy per unit area (or surface tension) of polymers is a fundamental property. It may be measured in the solid, liquid, or solution state, but perhaps most often the intention is to refer the measured value to the solid state. Hence, one approach involves measuring the surface tension of polymer melts and low molecular weight liquid polymers by conventional methods and using one of several equations to extrapolate to values for the polymer in the solid state.

Methods for determining the surface energy of solid polymers usually involve measuring the contact angle of a sessile liquid drop, and this methodology will be discussed in some detail. A relatively new technique for direct polymer surface energy measurement based on Johnson, Kendall, Roberts (JKR) (contact mechanics) theory will be discussed.
X‐Ray Scattering in Analysis of Polymers
Authors: Li Christopher Y. , Wang Bojie , Cheng Stephen Z.D.
Published: September 2006

It has been proved that X‐rays play a very important role in the characterization of polymers. A wealth of information concerning polymer structures and morphologies are accessible by using X‐ray techniques. X‐ray studies in the polymer area are based on the same principle as that in studies of other materials. The present review attempts to give a short summary of the roles that X‐rays play in modern polymer science.

The first three sections provide a brief introduction about the origin of X‐rays, the principle of the interaction of X‐rays and matter, and X‐ray diffraction. Section 4 briefly describes X‐ray instrumentation. In section 5, crystal unit cell and structural determination methods are discussed. The focus is on the use of uniaxially oriented polymers, as this is the most commonly used method for determination of polymer crystal structures. Crystallinity is another issue, which is specifically important to semicrystalline polymers. A short summary of the concept of crystallinity and its determination based on X‐ray diffraction is discussed. Polymer liquid crystals are a new field which has been growing rapidly since the late 1970s. X‐rays have again played an important role in liquid crystal phase determination. By combination of X‐ray techniques with other structure and thermal property measurements, almost every polymer liquid crystal phase can be identified. Section 6 discusses the small angle X‐ray scattering (SAXS) technique. The cause of X‐ray scattering in the small‐angle region in most polymers is due to the heterogeneous electron density distribution over distances that are large in comparison with the wavelength of the X‐ray (5–100 nm). SAXS is a powerful tool in semicrystalline morphology and block copolymer phase‐morphology studies. In the thin film field, X‐ray diffraction at small angles is also useful in determining the film thickness and interface structure.
Chromatography in Process Analysis
Authors: Clemons Jerry M.
Published: September 2006

Process chromatography is an analytical technique which provides for the on‐line separation and measurement of the components of a mixture in a chemical process. The chromatographic analyzers utilized for on‐line analysis must operate in a continuous and automatic manner, taking a fixed quantity of sample, separating the chemical components using adsorption or partitioning columns, and measuring the concentration of each with a detector. The chromatograph provides both quantitative results, by measuring the area of the peak generated as the components pass through the detector and qualitative results based on the retention time, which is measured from injection to detection.

The most commonly used process chromatographic analyzer is the process gas chromatograph because of its many applications in the hydrocarbon processing industry. A variety of valve, column, and detector configurations are available for these analyses from parts per million to percent levels. All samples must be gas phase or liquids which can be vaporized prior to analysis. The analyzers are controlled using a cyclic timing device which switches valves and columns as the components pass through the system to provide the necessary separation. This time cycle is a limitation of the technique for applications requiring continuous or very fast analysis times. Even with these limitations, the advantages of cost, flexibility, sensitivity, and reliability have made process gas chromatography (PGC) the most widely used analytical technique for on‐line process control.
Mass Spectrometry in Process Analysis
Authors: Olivares José A.
Published: September 2006

The mass spectrometer can provide a versatile, highly specific and sensitive tool for the analysis and control of industrial processes. More common techniques for industrial process control are gas chromatography and infrared spectroscopy. Ion mobility spectrometry and chemical sensors are slowly being introduced. Although mass spectrometry is relatively more complex and expensive to implement than these other techniques, the sensitivity and specificity offered is often unmatched. This article gives a general review of the roots of mass spectrometry as it applies to on‐line process control. A short discussion of instrumentation commonly used in the practice of this technique has been added and limited only to the more popular and currently commercially available instruments. These include sector, quadrupole and time‐of‐flight mass spectrometers. The capabilities and specifications of the different classes of mass spectrometers are discussed and compared. Specific sampling methodology for the operation of these instruments in on‐line processes is given. Also included is a discussion of common practices in the reduction of interferences and deconvolution of mass spectra from mixtures. In‐depth examples of industrial process and control applications have been selected and are discussed in the areas of biotechnology, technical incineration, petrochemical, and semiconductor production.
Sampling and Sample Preparation in Process Analysis
Authors: Creasy Kenneth E. , Francisco Troy W.
Published: September 2006

The purpose of this article is to introduce the reader to the important design characteristics of sampling and sample preparation systems for process analytical measurements, as well as to discuss several of the most commonly used configurations for gas‐ and liquid‐phase process streams. Design criteria essential to the success of any process analyzer installation are discussed at length, and the pitfalls associated with neglecting these items are highlighted. This article provides an overview of what must be considered when building the interface between the analytical instrument and the process stream. It is not intended to be a comprehensive dissertation on the subject or a tutorial. The reader is referred to literature references and textbooks for detailed explanations and relevant design formulae. In addition, we also provide several sections regarding calibration procedures, maintenance concerns, and safety considerations.
Titration Techniques for Process Analysis
Authors: Fossum Tore K. , Wolcott Duane K.
Published: September 2006

Titration remains a method of choice for quantitation and assay because the techniques are simple and the repeatability and accuracy can be better than with other analytical methods. Titration has moved from the laboratory bench to the process in order to obtain more timely information for the control of the process. This has become possible with the development of sampling techniques for getting clean samples from a pipe or tank, sensors suitable for remote measurements, highly precise automated titrant delivery pumps, and microprocessor‐based controllers adapting the time‐honored methodologies of the bench chemist.

Topics discussed in this paper include theory, sampling techniques, titration control, detection and applications using pH, argentometric, redox, and photometric sensors.
Ultraviolet/Visible Spectroscopy in Process Analyses
Authors: Saltzman Robert S.
Published: September 2006

Process analyzers based on selective ultraviolet (UV) and/or visible (VIS) absorption provide highly reliable on‐line composition monitoring and closed‐loop control throughout the process industries. Design criteria for ultraviolet/visible (UV/VIS) analyzers are different to those for laboratory instruments since the process instrument must meet the area electrical classification and often withstand harsh plant environments such as vibration, wide temperature swings, corrosive atmospheres and “dirty” samples.

The designs of various types of UV/VIS process analyzers are reviewed, and applications of these analyzers in major process industries are described.
Fourier Transform Infrared Spectroscopy in the Pulp and Paper Industry
Authors: Leclerc Denys F.
Published: September 2006

Fourier transform infrared spectroscopy (FTIRS) is the combined use of infrared (IR) light, for illuminating a light‐absorbing sample, with an interferometer, for producing an interference pattern from which an absorption spectrum characteristic of the sample is recovered through Fourier transformation. The majority of current IR pulp and paper applications involve the routine characterization of samples that contain variable amounts of water, a very strong IR absorber. Consequently, qualitative IR analysis of pulp and paper samples is best performed with a Fourier transform infrared (FTIR) spectrometer because of the larger optical throughput offered by an interferometer over a dispersive spectrometer. Also, an interferometer simultaneously records all IR frequencies present in the spectrum. These two advantages enable one to acquire high‐quality spectra in a few minutes or less. Additionally, since an interferometer accurately determines IR frequencies with the output of a visible‐light laser, quantitative determinations which use multivariate calibration methods such as partial least squares (PLS) are much less prone to instrument drift, and hence more accurate. Liquid and solid samples can be analyzed either neat or suitably diluted in a nonabsorbing matrix, through a variety of sampling techniques such as transmission, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), attenuated total reflectance (ATR), IR microscopy, and photo‐acoustic spectrometry (PAS). Detection limits for quantitative methods vary from 0.01 to 1 percent, depending on the sampling method and the complexity of a sample matrix. However, FTIR spectrometry cannot resolve more than a few components at a time in liquid and solid samples because of the presence of strongly overlapping bands. Therefore, FTIR spectroscopy must often be used in combination with separation techniques such as gas chromatography (GC) or solid‐phase extraction (SPE), especially when a complete analysis of the sample is required.
Mechanical Pulps, Ultraviolet/Visible Spectroscopy of Chromophores in
Authors: Schmidt John A.
Published: September 2006

Mechanical pulps are those where the starting wood is rendered into a suspension of fibers by the application of mechanical energy. Most of the lignin component is retained in the fibers by this process. The yellowish coloration of wood fiber is a consequence of the presence of chromophores in the lignin that absorb both visible and ultraviolet (UV) light. In most cases, the fibers must be bleached before they are acceptable for their final use. Lignin‐containing fibers are also susceptible to yellowing when exposed to UV light. To study the chemistry of these processes in pulp fibers, a technique capable of detecting chromophores in materials that both absorb and scatter radiation is needed. Diffuse reflectance ultraviolet/visible (UV/VIS) spectroscopy is such a technique. For nonscattering materials, the Beer–Lambert law provides a simple linear relationship between absorbance and the concentration of absorbers. This has been used for the analysis of soluble lignins and pulping liquors. For scattering materials, there is no similar simple linear relationship between reflectance and concentration of absorbers. A single reflectance measurement from an opaque sample can be related to the ratio of absorption to scattering by the Kubelka–Munk remission function, F(R
∞
) = k/s = (1 − R
∞
)
2
/2 R
∞
, where R
∞
is the reflectance of an opaque sample, k is the specific absorption coefficient and s is the specific scattering coefficient. The specific absorption coefficient k is linearly related to absorber concentration. If the scattering coefficient remains constant, the remission function is proportional to chromophore concentration. However, for many samples of interest, such as pulps prepared by different mechanical processes, scattering is not constant. Here, it would be uncertain whether a difference in remission function should be attributed to a change in absorption or a change in scattering. Also, in samples where the chromophores are not homogeneously distributed throughout the sample thickness, such as sheets yellowed by light, the linearity of the remission function no longer holds. In such cases, k can be calculated explicitly by taking additional reflectance measurements from thin transmitting samples that are suspended over backgrounds of known reflectance. While spectra of k versus λ (wavelength) are usually broad and featureless, difference spectra can reveal a surprising amount of detail about the changes in chromophore content.
Pyrolysis in the Pulp and Paper Industry
Authors: Sitholé B. Bruce
Published: September 2006

Analytical pyrolysis is a powerful technique that is seldom used in the pulp and paper industry. This article illustrates the utility of the technique to study the chemistry of wood and pulps, mechanistic aspects of pulping, troubleshooting process upsets in pulp and papermaking, and evaluating the quality of finished products. The technique has advantages over other analytical techniques in that little sample preparation is required and enough data can be obtained from very small amounts such as dirt spots on paper. In many cases good data can be obtained by analyzing the pyrolysis products by gas chromatography (GC) with flame ionization detection (FID). Detection with mass spectrometry (MS) offers the advantage of absolute qualitative and quantitative determination of the chemistry of the analytes. In many instances the chromatography can be improved by on‐line derivatization of the pyrolysis products with an alkylating agent.

This article takes the reader through a survey of the different types of analytical pyrolysis systems, through data analysis and processing, and examples of applications of analytical pyrolysis in the pulp and paper industry. Ample illustrations are used to highlight the usefulness of the technique.
Biological Oceanography by Remote Sensing
Authors: Srokosz M.A.
Published: September 2006

Biological oceanography may be studied from space using sensors on satellites that determine the color of the ocean. The presence of phytoplankton (microscopic algae) in the upper layers of the ocean changes the color of the water as seen from above. In simplified terms, this is due to the selective absorption of blue light by the phytoplankton pigments (primarily chlorophyll) which changes the appearance of the water from blue to green. These changes in color can be observed using a satellite‐borne spectroradiometer that measures the water‐leaving radiance in a number of bands in the visible part of the electromagnetic spectrum. The limitations of the technique are first, that only information on the phytoplankton in the upper layers of the ocean can be obtained (light does not penetrate very far into the ocean). Second, most of the signal measured by the satellite sensor originates in the atmosphere (due to the molecular and aerosol scattering of photons there), so careful correction for atmospheric effects is necessary if good ocean data are to be obtained. Of course, in the presence of clouds the sensor will not “see” the ocean surface at all, and no data will be obtained. Third, only one component of the ocean ecosystem, namely the phytoplankton, can be studied by this means. Despite these limitations, satellite observations of ocean color have given new insights into biological oceanography on a global scale that could not have been obtained by any other means of observation. Observations of ocean color have contributed to a better understanding of the biophysical interactions that determine the phytoplankton productivity, the seasonal and interannual variations of the phytoplankton biomass on global scales, and the role of phytoplankton in the climate system. They have also contributed to the improved modeling of biogeochemical processes in the ocean.
Elevation Modeling from Satellite Data
Authors: Toutin Thierry
Published: September 2006

Most geoscientific applications using georeferenced cartographic data need a good knowledge and visualization of the topography of the earth's surface. For example, mapping of geomorphological features is hardly feasible from a single image; three‐dimensional (3‐D) information has to be generated or to be added for a better interpretation of the two‐dimensional (2‐D) data.

Since the early emergence of earth observation satellites, researchers have investigated different methods of extracting 3‐D information using satellite data. Apart from a few early stereoimages acquired with hand‐held cameras during the Gemini and Apollo missions, the first experiments to extract 3‐D data using stereoviewing from space began with the Earth Terrain Camera (ETC) flown on board SkyLab in 1973–74.

Since these early experiments, various analog or digital sensors in the visible or in the microwave spectrum have been flown to provide researchers and geoscientists with spatial data for extracting and interpreting 3‐D information on the earth's surface. Although the shape‐from‐shading technique can be applied to optical sensor (OPS) images, stereoviewing using space camera or digital scanner images was, and still is, the most common method used by the mapping, photogrammetry and remote sensing communities.

However, side‐looking synthetic aperture radar (SAR) data also give the opportunity to extract 3‐D information using image‐processing techniques appropriate to the nature of the data. With SAR data, three main methods have been developed: radargrammetry, clinometry and interferometry. Radargrammetry (similar to the stereoviewing of optical data) uses two images acquired from different viewpoints to generate a stereopair and stereoviewing. Clinometry takes advantage of the SAR shading and shadowing in the image, and interferometry uses mainly the SAR signal data instead of the image. Other methods (polarimetry and altimetry) are also used for 3‐D information extraction.

This article reviews the different methods and sensors used to extract absolute or relative elevation and assesses their performance using the results from various research and commercial organizations. It also discusses the respective advantages, difficulties and constraints of the sensors, the methods and the technologies used to take into account the strength of each. It further assesses how they perform as complementary sources and systems for extracting elevation data in an operational context.
Hyperspectral Remote Sensing: Data Collection and Exploitation
Authors: Sandor‐Leahy Stephanie , Shepanski John
Published: September 2006

Hyperspectral imaging (HSI) spectrometers are remote sensing instruments that acquire images in a large number, typically hundreds, of contiguous spectral channels throughout the visible to long‐wave infrared (IR) portions of the spectrum from 0.4 to 14 µm.1 These systems are usually flown on aircraft platforms and use either platform motion or mirror mechanisms to scan a region of the earth's surface. The high‐resolution spectral features represented in the data cube allow for discrimination of materials in a scene. Because of the large number of spectral channels that are acquired by these instruments, they are termed hyperspectral, in contrast to multispectral instruments that obtain relatively few spectral bands. Like all remote sensing technologies, HSI must contend with data perturbations caused by atmospheric effects. In addition, data analysis must account for spectral mixing of multiple constituent materials within each pixel's field of view (FOV).
Polar Environments Assessment by Remote Sensing
Authors: Li Shusun
Published: September 2006

Polar regions are those surrounding the North and South Poles and situated within the Arctic and Antarctic Circles of the Earth. The polar regions are characterized by environments harsh to human and other organisms: low mean annual temperature and long nights and extensive snow and ice cover in winter. Because of the harsh conditions and poor accessibility, assessment of different aspects of the polar environment, such as light, temperature, snow and ice cover, soil and vegetation, largely relies on information acquired by remote sensors, i.e. airborne‐ and satellite‐borne electromagnetic instruments. This article briefly describes how and to what extent polar environmental information is currently derived through remote sensing methods.
Processing and Classification of Satellite Images
Authors: Wilkinson Graeme G.
Published: September 2006

Earth‐observing satellites primarily gather information about the environment as digital images acquired by multispectral imaging sensors. These images consist of large arrays of picture elements (pixels). Images are usually recorded in 3–7 spectral bands, though new generation sensors providing 18–36 spectral bands are in development. The spectral bands are located in the visible, infrared, millimeter, and microwave parts of the electromagnetic spectrum. The spatial resolutions of images at the subsatellite point at ground level (dictated by the sensor's instantaneous field of view, IFOV) are principally in the range 10 m–1 km depending on the satellite. Very‐high‐resolution satellite‐borne sensors providing imagery with resolution as high as 1 m will soon become routinely available. Images are primarily used for mapping Earth resources and monitoring the state of the environment (terrestrial, atmospheric, and oceanic). Pixels consist of digitized radiances which are usually quantized on a scale of 0–255. Interpretation of surface features requires the images to be processed and classified by computer. The processing involves several stages, typically: (1) geometrical rectification and adjustment to a suitable cartographic coordinate system, (2) correction and calibration for atmospheric or system effects on detected radiances, (3) classification or product generation. Classification involves the transformation of the detected multispectral radiances in the image into meaningful descriptors of the surface – usually as thematic classes which can be displayed as a map. The mathematical conversion process is usually based on training an appropriate classifier algorithm by use of example spectral radiances from known surface objects (ground truth data). Classifier algorithms may either be nonparametric or parametric (e.g. based on a statistical model). Neural network algorithms have found useful application as classifiers for satellite image data. Products may also be generated by computing environmentally meaningful indices from spectral radiances such as the normalized difference vegetation index (NDVI).
Satellite and Sensor Systems for Environmental Monitoring
Authors: Bakker Wim
Published: September 2006

More satellites monitoring some aspect of the Earth are launched each day. This article gives an overview of the science and practice of remote sensing (RS). It goes into the technical details of the physics behind RS, lists some typical contemporary and future Earth observing (EO) satellites, and explains the factors that determine the quality of images from space. This relatively short article cannot cover the entire field of RS, but the references and further reading list can be used for further study.
Sea Ice Monitoring by Remote Sensing
Authors: Sandven Stein , Johannessen Ola M. , Kloster Kjell
Published: September 2006

Sea ice is defined as ice which is formed as a result of freezing of seawater. Sea ice occurs at the surface of the ocean in areas where the surface temperature is cooled to the freezing point, which is about −1.8°C for sea water with a salinity of about 35 parts per thousand. Ice formed in lakes and rivers and icebergs coming from glaciers and ice sheets are not defined as sea ice.

Monitoring by remote sensing is defined as any measurement technique which can be used to observe sea ice repeatedly by instruments on board earth observation satellites. Monitoring also includes the process of making observational data available for users a short time after the observations have been obtained (i.e. a few hours). Remote sensing of ice can also be done with aircraft, submarines and other vehicles, but these techniques are not discussed in this article.
Temperate Forest Resource Assessment by Remote Sensing
Authors: Danson F. Mark
Published: September 2006

Remote sensing from airborne and spaceborne platforms provides a means of mapping forest resources at a range of spatial scales. Local‐scale mapping using aerial photography is a well established technique for determining stocking density, forest cover and forest health over relatively small areas. Satellite remote sensing can be used to map forest resources over larger areas, including regional to global scales. Techniques have been developed to map forest species and forest cover using spectral and spatial information in remotely sensed images. This work has been extended to map key biophysical and biochemical properties such as leaf area index (LAI) and leaf nitrogen content. These data have been coupled with other information such as meteorological data to drive process‐based ecosystem simulation models which may be used to monitor the production of forests and the rates of exchanges of energy and matter with the atmosphere and hydrosphere. Forests play a key role as a source of wood products but they are increasingly also being seen as playing a key role in the global climate system. Remote sensing is the only technique available to monitor forest resources at local, regional and global scales, and to develop an understanding of their role in the global ecosystem.
Tropical Forest Resource Assessment by Remote Sensing
Authors: Boyd Doreen S.
Published: September 2006

The earth's tropical forests are a global resource, requiring action for their wise utilization, management and protection at spatial scales from the local through to the global. The acquisition of data pertaining to tropical forest resources presents many challenges,
1
many of which may be overcome through the use of remote sensing. Reasons for the adoption of remote sensing for the assessment of tropical forest resources are compelling. Remote sensing can be used to observe the dynamics of tropical forests at almost any level of detail. It allows the frequent measurement and monitoring of the earth's tropical forests on a continuous basis, from which accurate and informed judgments on their resources at any given time can be made. Accordingly, there has been progressive evolution of remote sensing approaches for the collection of tropical forest resource information. With the imminent launch of new spaceborne sensors which will be able to acquire more information on tropical forests, remote sensing will continue to be a crucial tool in the assessment of tropical forest resources.
Automation of Analytical Control in the Steel and Metals Industry
Authors: Petin Jean
Published: September 2006

In this paper automation is defined as the replacement of operators by automatic devices. The genesis and the functions of automatic systems in the production control laboratories of the steel and metals industry are described.
Atomic Absorption and Emission Spectrometry, Solution‐Based in Iron and Steel Analysis
Authors: Del Monte Maria Grazia
Published: September 2006

The use of solution‐based atomic absorption spectrometry (AAS) and atomic emission spectrometry (AES) in iron and steel analysis is presented. The article is arranged in different sections dealing with the history relevant to the introduction and the acceptance of these techniques in iron and steel laboratories and their application to iron and steel analysis. A special emphasis is given to the application studies described in the literature for determining the almost forty elements which can be present in steels.

Topics such as sampling and sample preparation, spectrometric measurement, interferences, calibration, and quality assurance criteria are discussed. Finally a brief overview of the standard methods of analysis is presented.
Iron Ore, Sample Preparation and Analysis of
Authors: Bhargava Om P.
Published: September 2006

The iron ore industry is an important segment of the world economy. The main mineral oxides are magnetite and hematite. The composition of iron ore playsan important role in both the iron (blast furnace) and steelmaking operations. Sampling is done both at the source and at the destination. Sampling protocols and preparation are described. The determination of iron, phosphorus, silica and manganese by methods such as gravimetric (Si) and volumetric (P and Mn) have been replaced by more rapid photometric or flame atomic absorption spectrometry (FAAS) methods. Instrumental methods such as combustion high‐frequency furnace infrared (IR) (for C and S) FAAS and graphite furnace electrothermal methods, X‐ray fluorescence (XRF) and inductively coupled plasma (ICP) spectrometric methods are used to determine analytes for routine process control. These methods are illustrated in the article. Rapid methods for chemical analysis and quality control, developed by the author, could also be cost effective.
Nickel Ore and Metals Analysis
Authors: Johnston J.R.
Published: September 2006

This article examines contemporary routine and umpire quality methods for the analysis of nickel ores, nickel metal and nickel alloys. Sample preparation and sampling are also discussed, but the emphasis is on sample preparation and analysis, since sampling is all too often done by people not part of the analytical laboratory.

In order to analyze fully these materials, a laboratory must have at its disposal a wide range of instruments and methods, from the classical to the most modern, and frequently combinations of both. In keeping with the theme of this Encyclopedia, detailed methods are not given, and the reader should consult the references. The references themselves cover the period from roughly 1972 through 1997 but are not to be considered a definitive list. Unfortunately, most of the modern methods of analysis developed by chemists in nickel producers' laboratories have not been published, except as international or national standards. As an aid to the reader, a summary of International Organization for Standardization (ISO) and national standards is given immediately before the References. The author apologizes for any errors or omissions.

The section on nickel ores is divided into two broad classifications: sulfide and lateritic ores. Greater emphasis is given to the sample preparation of laterites since they are more difficult to handle and many laboratories do not have as much experience working with them as with sulfides. Each broad classification is broken down into the analysis of “pay metals”, which are the reason the ore is mined, elements of environmental concern and other elements which are required for the metallurgical processing of the ore.

Products from refineries fall into three broad categories: nickel metal in various forms, nickel oxides and ferronickel. For nickel metal, the emphasis is on trace‐element determinations; for nickel oxides and ferronickel, methods for the determination of nickel are also discussed.

Nickel alloys cover a wide range of materials, from stainless steels to high‐nickel “superalloys”. For these samples the analytical requirements range from the major components of the alloy to minor alloying constituents to trace‐element determinations.

As an aid to the analytical chemist in the laboratory, tables are presented summarizing recommended methods of analysis, and in most instances an alternative method, in case the laboratory does not have the equipment necessary to select the first choice. These methods have proven themselves in the laboratories of nickel producers and commercial laboratories familiar with the analysis of nickel‐bearing samples.
Thermal Evolution Methods for Carbon, Sulfur, Oxygen, Nitrogen and Hydrogen in Iron and Steel Analysis
Authors: Lawrenz Dennis A. , Mitchell Joel
Published: September 2006

A thermal evolution method is a method of destructive analysis in which the sample is subjected to heating, combustion, or fusion1 to quantify the chemical composition of iron and steel. Thermal evolution methods have been used for many years to determine carbon, sulfur, oxygen, nitrogen, and hydrogen contents of iron and steel. Carbon and sulfur are determined using combustion techniques. Oxygen and nitrogen are determined using inert gas fusion techniques. Hydrogen is determined using either inert gas fusion or hot extraction techniques. Analytical instrumentation for all of these techniques is commercially available.
X
‐ray Fluorescence Spectrometry in the Iron and Steel Industry
Authors: Bonvin Didier
Published: September 2006

In reviewing the current status of wavelength‐dispersive X‐ray fluorescence (WDXRF) spectrometry in the iron and steel industry, attention is given to aspects such as sampling and specimen preparation, calibration requirements and analytical demands for the various material types and the choice of instrument configuration.
Auger Electron Spectroscopy in Analysis of Surfaces
Authors: Lannon John M. , Stinespring Charter D.
Published: September 2006

Auger electron spectroscopy (AES) is an electron energy spectroscopy which probes the electronic energy levels of atoms, using electron or X‐ray beam stimulation. Irradiation of a sample with one of these stimuli causes electron emissions which can be energy analyzed to obtain an energy distribution. Since the energies of the Auger electrons are characteristic of the atomic core and/or valence level energies, they contain chemical information about their source atoms. As a result, the recorded energy spectra can be analyzed to determine the atomic composition (atomic percent) of the sample, and, in some cases, extract chemical bonding information. Further, since the escape depth of Auger electrons is limited to the first few monolayers of the sample, the technique has a high surface sensitivity. When used in conjunction with an ion source, AES can provide compositional information as a function of depth (depth profiling). Although AES was initially used primarily for fundamental surface science applications, the technique has developed into an important analytical tool for a broad range of surface and materials science applications, including surface reaction studies, surface segregation studies, and thin film growth studies.
Electron Energy Loss Spectroscopy in Analysis of Surfaces
Authors: Erskine J.L.
Published: September 2006

Electron energy loss spectroscopy (EELS) is a versatile and sensitive probe of electronic and vibrational excitations at surfaces. The technique is extensively used as a research and analytical tool in a broad range of surface science applications including research on intrinsic physical and chemical properties of surfaces, chemisorption phenomena, and chemical processes at surfaces. The spectroscopy is based on measuring the energy loss and momentum transfer of electrons in a highly collimated, monochromatic (narrow energy spread) beam after the electrons scatter from a surface. Vibrational excitations of atoms and molecules adsorbed on surfaces, collective excitations of ordered chemisorbed structures, the intrinsic collective excitations of surface atoms (surface phonons), and collective electronic excitations (surface plasmons) can be studied using the technique. Under favorable conditions, vibrational losses from surface adsorbate concentrations below 10−3monolayer (1012atoms cm−2) can be detected. EELS is a surface science probe, typically requiring an ultrahigh vacuum (UHV) environment, and is generally employed in conjunction with complementary surface analytical probes such as Auger electron spectroscopy (AES), low‐energy electron diffraction (LEED) and thermal desorption mass spectroscopy (TDS). EELS is an ideal tool for determining surface chemical composition, and provides vibrational loss spectra similar to infrared reflection absorption spectroscopy (IRAS), Raman spectroscopy, and helium atom scattering spectroscopy (HAS).