Numerical Aspects of FE Simulations of Granular Flow in Silos

Some important numerical aspects concerning the finite-element simulation of granular flow are presented. The main topic of this paper is the so-called “switch” phenomenon, which is a stress peak at the junction of the vertical and the inclined part of a mass flow silo during its discharge. Case studies prove that the FE simulation of silos and simplified systems should be handled with great care, as many wall pressure peaks occurring at places where the shape of the silo is changing may well be caused by numerical corner singularities. Other numerical aspects lead to consequences for the filling process and the opening phase of silo emptying.     

Social exchange, equity, and commitment: Structural equation modeling of dating relationships.

Used structural equation modeling in 2 studies to evaluate the social exchange (SE) hypothesis, which states that relationship commitment results from satisfaction with the relationship, paired with the limited availability of desirable alternative relationships. College students in intimate relationships completed questionnaire measures of commitment, satisfaction, perceptions of alternatives, and inequity. The initial study, with 238 Ss, supported the SE model but also suggested that perceptions of alternatives involved separating the field of desirable alternatives from the field of available alternatives. Study 2, with 423 Ss, was a replication of Study 1. It also ruled out gender differences, and tested and supported an expanded SE model, which included the construct inequity as an additional intrinsic factor that had substantial indirect influences on relationship commitment as mediated through its effect on satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Damping of fourth sound in4He due to normal fluid flow

Measurements of the attenuation of fourth sound were made in superfluid⁴He contained in several porous media with characteristic sizes sufficiently large to permit some normal fluid flow. The data are for pressures between vapor pressure and 25 bar and for temperatures between 1.4 K and the-line. The attenuation was dominated by viscous dissipation associated with the normal fluid flow. For a given medium, it varied by nearly two orders of magnitude over the pressure and temperature range of the experiment. Analysis of the data along isobars and isotherms in terms of an idealized model for the porous medium yielded a unique temperature- and pressure-independent characteristic size for each medium.     

Superfluid fraction of4He from 1.5 K toT λ(P) and from vapor pressure to the melting curve

New measurements of the first-, second-, and fourth-sound velocities are reported and used to obtain the superfluid fraction _s / at pressures from vapor pressure to the melting curve and from 1.5 K to within 1% of the superfluid transition temperatureT (P). Close toT , the new results agree very well with previous measurements by Greywall and Ahlers. At low temperatures they agree well with the tabulations by Maynard; but in the range within 10% or so ofT (P) and at the higher pressures they differ from Maynard's values by several percent.     

Design specifications in the flowsheet simulation of complex solids processes

In the present work a method for the treatment of design specifications in the simulation of complex solids processes has been developed.Adding a design specification to the flowsheet of a given solids process means that the solid product should fulfill a certain requirement. For example, its Sauter mean diameter should be kept within a certain interval or the mass fraction of particles above a certain threshold should be kept below a certain limit. The method developed here is not only able to handle product specifications but also other stream properties of the process. These properties can be either distributed or concentrated. Even dependently distributed properties e.g. a particle size-dependent contamination can be handled. The treatment of design specifications has been implemented as an extension of the flowsheet simulation system SolidSim.Practical applications of the implemented extension are illustrated with three examples: (i) a simple process for the preparation of brown coal, (ii) a process for the treatment of gravel and sand and (iii) a complex process for the mechanical separation and dewatering of harbor sediments contaminated with heavy metals.     

食品的异味（上）

1　绪言和定义异味 (ｏｆｆｆｌａｖｏｒ)又称之为杂味 (ｔａｉｎｔ)和怪味(ｏｆｆｎｏｔｅ)。按Ｋｉｌｃａｓｔ[1 ] 的观点 :染上杂味可理解为食品带有不愉快的气味或味道。它们来自食品外部 ,例如 ,由于包装材料造成的气味污染。而异味则归咎于食品本身所引起的 ,例如在食品储存过程中的氧化分解。这种区别在某些场合可能是有帮助的 ,但是 ,它们难以在文献中和语言上严格地区分。因此异味和怪味通常被理解为各种不正常气味的统称。异味的定义很简单 :任何这种产品在正常情况下不应具备的气味 ,味道或者三叉神经的感觉[2 ] 。但是有一点必…     

Nuclear hydrogen: An assessment of product flexibility and market viability

Nuclear energy has the potential to play an important role in the future energy system as a large-scale source of hydrogen without greenhouse gas emissions. Thus far, economic studies of nuclear hydrogen tend to focus on the levelized cost of hydrogen without accounting for the risks and uncertainties that potential investors would face. We present a financial model based on real options theory to assess the profitability of different nuclear hydrogen production technologies in evolving electricity and hydrogen markets. The model uses Monte Carlo simulations to represent uncertainty in future hydrogen and electricity prices. It computes the expected value and the distribution of discounted profits from nuclear hydrogen production plants. Moreover, the model quantifies the value of the option to switch between hydrogen and electricity production, depending on what is more profitable to sell. We use the model to analyze the market viability of four potential nuclear hydrogen technologies and conclude that flexibility in output product is likely to add significant economic value for an investor in nuclear hydrogen. This should be taken into account in the development phase of nuclear hydrogen technologies.     

Volatile Exudates from the Oribatid Mite, <Emphasis Type="Italic">Platynothrus peltifer</Emphasis>

Gas chromatographic-mass spectrometric analysis of whole body extracts of Platynothrus peltifer, a desmonomatan oribatid mite that belongs to the family Camisiidae, exhibited a basic profile of seven compounds, comprising the monoterpenes neral, geranial, and nerylformate; the aromatics 3-hydroxybenzene-1,2-dicarbaldehyde (= -acaridial) and 2-formyl3-hydroxybenzyl formate (= rhizoglyphinyl formate), and two unsaturated C₁₇-hydrocarbons, 6,9-heptadecadiene and 8-heptadecene. Neryl formate, -acaridial, and rhizoglyphinyl formate were the main components and amounted to 80% of the extracts. With the exception of -acaridial (relative abundance varied considerably among samples), this chemical profile was consistently present in extracts of P. peltifer from nine different localities in SE-Austria. In addition, two further components, 2,3-dihydroxy benzaldehyde and 7-hydroxyphthalide, both probably of non-oil gland origin, infrequently were detected in the extracts. The aromatic compound rhizoglyphinyl formate, also known from Astigmata, was found for the first time in extracts of Oribatida, whereas all other compounds have already been reported from other oribatid species. The hydrocarbons are generally considered to represent plesiomorphic characters of mite oil gland secretions, whereas the monoterpenes and -acaridial form a part of the so-called astigmatid compounds that are thought to be characteristic for middle-derivative Mixonomata and all more highly derived oribatid groups (including Astigmata).     

Colorimetric determination of urease activity in soybean meals

Summary A quantitative method for the determination of urease activity in soybean meals is described. The procedure is based on the incubation of the meal sample with a known amount of urea, followed by colorimetric determination of the urea with p-dimethylaminobenz-aldehyde after incubation. Urease activity is expressed as the amount of urea decomposed under the specified conditions. The test is both accurate and specific for urease. The method is very reproducible and sensitive, especially at low urease activities. Presented at the spring meeting, American Oil Chemists' Society, Memphis, Tenn., April 21 to 23, 1958.     

Stable and Effective Full-Wave PEEC Models by Full-Spectrum Convolution Macromodeling

A novel technique for time domain partial element equivalent circuits (PEECs) modeling is presented. The PEEC method is a well-known numerical method for creating full-wave models of interconnection structures in the frequency and time domains, which are being used for modeling electromagnetic compatibility (EMC) problems. The time domain solutions by PEEC can show the so-called late-time instabilities. Several attempts to overcome this problem have been made in the literature. The cause for instability has been revealed, and a stable time domain model has been given, however, with a reduced computational efficiency. A stable full-wave PEEC model based on a convolution macromodeling with a faster computation time is developed and tested in this paper