Database Of Physical Properties Research Articles

A knowledge base for the apparent mass diffusion coefficient (DEFF ) of foods

A Database of Physical Properties of Foods is to be created in the frame of the European Concerted action project (DOPPOF). Among the various properties, the diffusion properties of foods with respect to moisture, salt and other solute components are to be covered. The aim of the Database is to provide data which were carefully selected, evaluated and entered the under construction database shell. The effective or apparent diffusion property is an important mass transfer property. Values of effective or apparent diffusivities of foods are abundant in the literature and their derivation is the outcome of the application of the Fickian approximation model for mass transfer in foods. The use of chemical potential to be considered as the driving force and the approach “on cell level” is compared to the Fickian approximation approach. The modern alternative has already started to be applied and it is expected to gain increasing importance in the near future. The purpose of this paper is to provide a “knowledge base” for the use of the effective diffusivity data reported in the literature. The Food scientist or Food engineer is warned of pitfalls observed when using such data. Suggestions are also given for the kind of usage or the applicability extent of the data. A description of the main diffusivity measurement methods in both liquid and solid products is, also, given. In addition, measurement methods of activity coefficients are discussed.

Pedotransfer functions to estimate soil water retention parameters for a modified Brooks–Corey type model

This paper presents pedotransfer functions to estimate soil water retention parameters of the Hutson–Cass modified form of the Brooks–Corey equation from soil texture, bulk density and organic carbon content. Multiple regression equations are developed from a subset (286 soil horizons) of the soil physical properties database of England and Wales. For this dependent dataset, the average root mean square error (RMSE) in soil water content was 0.043 m 3 m −3, while ca. 68% of the entries had RMSE values less than 0.05 m 3 m −3. The functions were then validated against the remaining 1678 soil horizons in the database. This independent test gave a mean RMSE nearly as small (0.048 m 3 m −3) as that obtained for the original dataset. This degree of accuracy is considered acceptable, given the simple form assumed for the water retention function. The functions were shown to be robust, except for organic horizons (organic carbon content >5%) and/or for soils of small bulk density (<0.9 g cm −3).

Characterization of metal contacts on and surfaces of cadmium zinc telluride

In the past several years significant progress has been made in building a database of physical properties for detector quality Cd x Zn 1− x Te (CZT) ( x=0.1–0.2) crystal material. CZT's high efficiency combined with its room temperature operation make the material an excellent choice for imaging and spectroscopy in the 10–200 keV energy range. For detector grade material, superior crystallinity and high bulk resistivity are required. The surface preparation during the detector fabrication plays a vital role in determining the contact characteristics and the surface leakage current, which are often the dominant factors influencing its performance. This paper presents a surface and contact characterization study aimed at establishing the effects of the surface preparation steps prior to contacting (polishing and chemical etching), the choice of the metal and contact deposition technique, and the surface oxidation process. A photoconductivity mapping technique is used for studying the effects of different surface treatments on the surface recombination.

An overview of compiling, critically evaluating, and delivering reliable physical property data from AIChE DIPPR® Projects 911 and 912

The goal of AIChE DIPPR® Projects 911 and 912 is to develop a comprehensive, consolidated database of physical properties for those chemical species which are regulated by various agencies of the US government, and are important to the chemical process industry. Environmental, safety and health (ESH) properties are the prime focus of the data collection and validation efforts of the two projects. Project 911, a database compilation effort, collects data for 700 chemicals and 55 physical properties. These properties include aqueous solubility, viscosity, vapor pressure, flash point, octanol–water partition coefficient, and bioconcentration factor. Project 912 is a complementary effort which focuses on the review of existing physical property prediction techniques and developing new estimation algorithms where none exist. Limited mixture data (e.g., infinite dilution vapor/liquid equilibrium measurements) are also being researched. Work is continuing on the critical assessment of the quality of data within the Project 911 database. Available literature data are compiled and categorized according to quality. Recommended data values and correlation statistics are provided as part of the Project 911 software product. To automate the data evaluation effort, a computerized Statistical Process Control (SPC) data review system has been designed. The Project 911 database is being developed to support engineering and regulatory calculations and to work in tandem with the estimation protocols established by Project 912 to predict properties for chemicals not readily available through literature sources.

Opportunities and Limitations of Mathematical Optimization Methods in Process Synthesis

The efficiency of chemical processes mainly depends on decisions, which are made in the phase of process synthesis. The industrial application of mathematical methods for process synthesis mainly tended to fail in the past due to the existing MINLP systems. With access to a physical property database and using a two-stage approach, the authors report on the developed mathematical program system (PSANO).

Computer-Assisted Mineral Identification for Introductory Geology Courses

Mineral Database is an interactive computer program that allows students to quickly identify minerals by their physical properties. The program incorporates color images and a physical-properties database, called Mineral KnowledgeBase, which includes individual histories and backgrounds of the common rock-forming minerals. The program was written by one of the authors (Yavine) in Visual BASIC and runs under Microsoft Windows. The package currently includes over 150 of the most common minerals although additional minerals, or mineral categories, such as oxides, sulfides, phosphates, and so forth could easily be added to customize the program for use in upper-level courses. A search/match module allows students to use the program to identify minerals if physical properties are known or conversely to look up physical properties of a particular mineral. Use of the program in an introductory physical-geology class to aid in the identification of minerals was enthusiastically received by students when used in conjunction with hand specimens and other, more traditional, means of instruction.

Chempak : Physical-properties database structure and development

Chempak (commercial physical properties database and properties estimation software) gives the thermodynamic and transport properties of pure compounds as functions of temperature and pressure for both liquid and vapor phases. Compound liquid properties are defined from the melting to the critical points. Vapor properties are defined from the melting point to 1300 K. The user may define up to 50 mixtures of compounds drawn from the database. In addition, the user may add up to 100 additional compounds defined by using the same techniques employed to construct the main database. Vapor properties are defined by the use of the Lee–Kesler and the Wu and Stiel equations of state. Vapor viscosity and thermal conductivity are defined using corresponding states methods. Liquid thermodynamic properties (except specific heat) are derived from the equation of state. All other liquid properties are defined by setting 11 data values from the melting to the critical point. The resulting property data arrays are interpolated against temperature.

A Survey for H 2 O Megamasers in Active Galactic Nuclei. II. A Comparison of Detected and Undetected Galaxies

A survey for H2O megamaser emission from 354 active galaxies has resulted in the detection of 10 new sources, making 16 known altogether. The galaxies surveyed include a distance-limited sample (covering Seyferts and LINERs with recession velocities less than 7000 km s-1) and a magnitude-limited sample (covering Seyferts and LINERs with mB ≤ 14.5). In order to determine whether the H2O-detected galaxies are typical active galactic nuclei (AGNs) or have special properties that facilitate the production of powerful masers, we have accumulated a database of physical, morphological, and spectroscopic properties of the observed galaxies. The most significant finding is that H2O megamasers are detected only in Seyfert 2 and LINER galaxies, not Seyfert 1's. This lack of detection in Seyfert 1's indicates either that they do not have molecular gas in their nuclei with physical conditions appropriate to produce 1.3 cm H2O masers or that the masers are beamed away from Earth, presumably in the plane of the putative molecular torus that hides the Seyfert 1 nucleus in Seyfert 2's. LINERs are detected at a similar rate to Seyfert 2's, which constitutes a strong argument that at least some nuclear LINERs are AGNs rather than starbursts, since starbursts have not been detected as H2O megamasers. We preferentially detect H2O emission from the nearer galaxies and from those that are apparently brighter at mid- and far-infrared and centimeter radio wavelengths. There is also a possible trend for the H2O-detected galaxies to be more intrinsically luminous in nuclear 6 cm radio emission than the undetected ones, though these data are incomplete. We find evidence that Seyfert 2's with very high (NH > 1024 cm-2) X-ray-absorbing columns of gas are more often detected as H2O maser emitters than Seyfert 2's with lower columns. It may be that the probability of detecting H2O maser emission in Seyfert galaxies increases with increasing column of cool gas to the nucleus, from Seyfert 1's through narrow-line X-ray galaxies to Seyfert 2's.

Chemical Dynamics and Bond-Order Potentials

Tremendous advances in computing speed, increasingly clever algorithms, and more accurate interatomic-force models have made atomistic simulation a powerful tool in many areas of materials science and engineering. Indeed, from traditional areas such as the study of grain boundaries, fracture, and point defects to somewhat less traditional areas such as nanometer-scale engineering and device fabrication, atomistic simulations are providing exciting new data and insights that cannot be obtained in any other way. Central to the success of an atomistic simulation is the use of an appropriate force model. For simulations requiring large systems and/or long times, the computational efficiency offered by classical potential-energy functions is necessary. However, obtaining quantitative results requires a model that can both accurately describe an appropriate database of physical properties and that is transferable to structures and dynamics beyond those to which it is fit. The latter property is especially critical if an atomistic simulation is to have useful predictive capabilities. While an extensive and well-chosen database from which parameters are determined is important, transferability ultimately depends on the chosen functional form. The definitive mathematical form, however, has yet to be developed.This article covers my attempts to develop classical potential-energy functions based on an empirical bond-order formalism that put qualitative and semiquantitative features of chemistry into large-scale condensed-phase simulations. To help explain this work, the next section gives a brief tutorial of the “chemistry” of few-body potentialenergy surfaces. Although familiar to chemists, the concepts discussed in this section may not be as familiar to mate rials scientists and engineers. A discussion of the bond-order formalism and how it can be related to both solid-state structure and chemical dynamics follows. The article ends with a discussion of two applications of this formalism, modeling chemical dynamics near a shock front and the reactive chemistry of diamond deposition.

SENSITIVITY ANALYSIS IN OIL SPILL MODELS: CASE STUDY USING ADIOS

ABSTRACT The Hazardous Material Response and Assessment Division (HAZMAT) at the National Oceanic and Atmospheric Administration uses the oil weathering software package named Automated Data Inquiry for Oil Spills (ADIOS) to investigate the oil weathering process. This model combines a database of physical and chemical properties of oils with a simulation model computing mass losses, density, viscosity, and water content of an oil spill due to evaporation, dispersion, and emulsification. A first-order sensitivity analysis of the ADIOS evaporation algorithm indicates that it might be possible to provide a taxonomy of oils with respect to the reliability of results generated by the model.

The use of regression equations for quality control in a pesticide physical property database

Quality control is a crucial aspect of database management, particularly for physicochemical parameters that are widely used in modeling environmental fate processes. Complete rechecking of original studies to verify environmental fate parameters is time consuming and difficult. This paper evaluates an alternative, more efficient approach to identifying database errors. The approach focuses verification efforts on a targeted subset of entries by making use of the relationship between water solubility (S) and soil organic carbon partition coefficient (K oc ). Two regression equations, one selected from the literature and one calculated from entries in the database, were used to evaluate the reasonableness of (S, K oc ) pairs among control compared to the targeted outlier group from a total of 59 pesticides. Our hypothesis was that (S, K oc ) pairs that lay far from the regression line were more likely to be in error than those that fit the regression. Database values were checked against original studies. Identified errors in the database included coding mistakes, miscalculations, and incorrect chemical identification codes. The error rate in outlier (S, K oc ) pairs was about twice that of pairs that conformed to the regression equation; however, the error rate differential was probably not large enough to justify the use of this quality control method. Through our close scrutiny of database entries we were able to identify administrative practices that led to mistakes in the data base. Resolution of these problems will significantly decrease the number of future mistakes.

Functionality and Implementation of a Knowledge-Based Flowsheet-Oriented User Interface for the Dynamic Process Simulator DIVA

A knowledge-based simulation model editor for the dynamic process simulator DIVA allows flowsheet generation guided by object-oriented, hierarchically structured knowledge about process-units, and by rules ensuring the consistency of parameters and connections between process-units. A physical property interface helps the user to choose from various calculation methods offered by the simulator's library. Parameters for the substances at hand are retrieved from inhouse and commercially available physical property databases. The tight integration of facilities for experiment control and flowsheet animation will be the basis for future studies in knowledge-based process optimization and process control.

Computerized spill hazard evaluation models

Accidents in the transportation or storage and handling of chemicals may result in the release of dangerous chemicals. Rapid prediction of hazard areas are essential so that the necessary remedial actions. This paper describes a system being developed for the U.S. Coast Guard. The system consists of state-of-the-art mathematical models describing different sources for chemical releases (pressurized storage tanks, bulk storage tanks, barge, rail car and road transports) and hazardous behavior in the environment (two-phase jet flow, instantaneously released vapor cloud, dispersion of heavy gases with liquid aerosols, reactive chemical dispersion in air, jet fires, pool fire thermal radiation, explosion effects, water dispersion in rivers and streams, etc.) . The system has a physical and chemical property database (including temperature dependent properties) for over 1200 chemicals which are used in the mathematical models. This paper discusses the various features of the system. Details of the mathematical models are not given since these have been published before. The questions of how an on-scene commander responding to a chemical spill accident can utilize these models and the level of confidence that can be placed in the model results are discussed.

Use of a Database of Chemical, Mineralogical and Physical Properties of North American Fly Ash to Study the Nature of Fly Ashand Its Utilization as a Mineral Admixture in Concrete

AbstractA database of chemical, mineralogical and physical characteristics of North American fly ashes has been assembled by the Western Fly Ash Research, Development and Data Center. One-hundred and seventy-eight representative ashes were divided into three groups according to their analytical CaO content: low-calcium, &lt;10%; intermediate-calcium, 10–20%; high-calcium, 20+%. Statistical analyses were performed within each of the three groups. Thirty-two plots relating chemical composition, mineralogy and physical test results are presented. Extensive discussions relating the chemistry and mineralogy of the ash to the source coal, the distribution of the chemical constituents among crystalline and glassy phases, and the reactions of these phases in concrete are given. The consistency of high-calcium fly ash generated at a Midwestern U.S. power station fired with Wyoming bituminous coal was studied using ninety-three ashes collected over a two year period. The availability of mineralogy for each ash leads to a more thorough understanding of the bulk chemical and physical test results used in evaluating fly ashes for utilization, and in modeling their behavior after disposal

Correlations of Chemistry and Mineralogy of Western U.S. Fly Ash

Fly ashes derived from low-rank coals mined principally in Montana, Wyoming and North Dakota are being studied by the Western Fly Ash Research, Development and Data Center [1]. Previous studies of the mineralogy of western U.S. fly ash by McCarthy et al. [1–3] using x-ray diffraction (XRD) form the framework of the present study. A database of chemical, mineralogical and physical properties, along with precursor coal characteristics, is being assembled. Based on studies to date of several hundred fly ash samples derived from lignite and subbituminous coals, as well as from several bituminous ashes, correlations of chemistry and mineralogy have been hypothesized and are being tested. These correlations are discussed below.