Two-fluid model for the simultaneous flow of colloids and fluids in porous media

To describe the velocities of particles such as ions, protein molecules and colloids dispersed or dissolved in a fluid, it is important to also describe the forces acting on the fluid, including pressure gradients and friction of the fluid with the particles and with the porous media through which the fluid flows. To account for this problem, the use of a two-fluid model is described, familiar in the field of fluid mechanics, extended to include osmotic effects. We show how familiar relationships follow in various situations and give examples of combined fluid/particle transport in neutral and charged membranes driven by a combination of electrostatic, diffusional and pressure forces. The analysis shows how the same modeling framework can be generally used both for multidimensional electrokinetic flow through macroscopic channels and around macroscopic objects, as well as for mean-field modeling of transport through porous media such as gels and membranes

A philosophical context for methods to estimate origin-destination trip matrices using link counts.

This paper creates a philosophical structure for classifying methods which estimate origin-destination matrices using link counts. It is claimed that the motivation for doing so is to help real-life transport planners use matrix estimation methods effectively, especially in terms of trading-off observational data with prior subjective input (typically referred to as 'professional judgement'). The paper lists a number of applications that require such methods, differentiating between relatively simple and highly complex applications. It is argued that a sound philosophical perspective is particularly important for estimating trip matrices in the latter type of application. As a result of this argument, a classification structure is built up through using concepts of realism, subjectivity, empiricism and rationalism. Emphasis is put on the fact that, in typical transport planning applications, none of these concepts is useful in its extreme form. The structure is then used to make a review of methods for estimating trip matrices using link counts, covering material published over the past 30 years. The paper concludes by making recommendations, both philosophical and methodological, concerning both practical applications and further research

How about building a transport model of the world?

The paper provides a specification, created by the recently completed BLUEPRINT project, for a world transport network model. The model should be able to make predictions (up to 100 years into the future) of transport flows throughout the world and hence make predictions of global climate-changing emissions arising from transport. Furthermore, the model should: cover both passenger and freight traffic; feature all modes of transport (road, rail, non-motorised, water, air and pipeline); and represent both local traffic and long-distance traffic. The paper describes how the model will be structured as the combination of a global model (distinguishing between approximately 30 different geographic regions of the world) and a number of regional and sub-regional models. Wherever feasible, existing regional models will be used in this system, or at least simplified versions of such models. The overall modelling system should be owned jointly by an international network of world transport modellers, welcoming easy entry to other modellers who subscribe to the underlying spirit of the network. The paper recognises the scientific complexities associated with the uncertainties of predicting 100 years into the future and with difficulties arising from the likely differences in modelling philosophy between the (already existing) regional models that might be used in the modelling system. In order to tackle these complexities, the paper defines a number of philosophy of science reference points. At the core of these reference points is the distinction between objectivity and subjectivity. The paper finishes with a number of suggestions for next steps in building the model

Geological notes and local details for 1:10 000 sheet TM 49 NW : Thurlton : part of 1:50 000 sheet 162 (Great Yarmouth)

This report describes the geology of the 1:10,000 sheet TM 49 NW (Figure 1) which is included i n the l:5O,OOO Great Yarmouth (162) geological map. The area was first surveyed by J H Blake and C Reid as part of the Old Series oneinch sheets 67 SE (JHB) and 66 SE (CR/JHB) published i n 1882 and 1881 respectively. The primary six-inch survey of the Thurlton area was made by P M Hopson in 1985 under the direction of D r R G Thurrell, Programme Manager, Eastern England Land Survey. Uncoloured dye-line copies of the map can be obtained from the British Geological Survey, Keyworth. The area described covers part of the broad valley near the confluence of the lower Yare and Waveney rivers, together with some gently undulating country which rises towards the south west to a plateau founded on boulder clay

Tribological investigations of the piston assembly and liner of a gasoline engine

The automotive industry is being forced towards greater efficiency, increased engine power from smaller engines and lower environmental impact by both governmental legislation and public opinion. Oil drain intervals are increasing whilst emissions legislation limit the use of current wear protection and antioxidant additives containing elements such as phosphorus and sulphur. To address these demands and challenges an increased understanding of the link between lubricant degradation, its transport and residence time, and the effect on piston assembly tribology is required. The aim of the work reported in this paper was to further develop the understanding of the effect degraded lubricants have on piston assembly tribology. The small oil volumes and environmental conditions in the piston assembly make the affective lubrication and protection of components in this region one of the most challenging areas of tribology. This was carried out through an extensive experimental programme using a research engine, tribometer testing and chemical and rheological analysis of lubricant samples

News from the "Dentist's Chair": Observations of AM 1353-272 with the VIMOS IFU

The galaxy pair AM 1353-272 nicknamed "The Dentist's Chair" shows two ~30 kpc long tidal tails. Previous observations using multi-slit masks showed that they host up to seven tidal dwarf galaxies. The kinematics of these tidal dwarfs appeared to be decoupled from the surrounding tidal material. New observations of the tip of the southern tidal tail with the VIMOS integral field unit confirm the results for two of these genuine tidal dwarfs but raise doubts whether the velocity gradient attributed to the outermost tidal dwarf candidate is real. We also discuss possible effects to explain the observational difference of the strongest velocity gradient seen in the slit data which is undetected in the new integral field data, but arrive at no firm conclusion. Additionally, low-resolution data covering most of the two interacting partners show that the strongest line emitting regions of this system are the central parts.Comment: Comments welcome, especially ideas to explain the difference between the two datasets. 5 pages, 3 figures, to appear in "Science Perspectives for 3D Spectroscopy", eds. M. Kissler-Patig, M. M. Roth and J. R. Walsh, ESO Astrophysics Symposi

ISO 9000 certification benefits reality or myth?

Given the rapid recent growth in ISO 9000 applications and the business performance benefits being claimed for it by National Accreditation Registrars, it is timely to review the research in this area to see if any substantial proof exists for these claims. The paper explores the literature and finds that there is no proven link between quality certification (ISO 9000) and improved business performance. However, it is clear from the research reviewed on business performance factors, that better quality does have a consistent, positive relationship with business performance. Combining these findings leads to the inference that quality certification to ISO 9000 standards is not consistently associated with having a quality assurance system that delivers improved process control, or better quality. We conclude that the National Accreditation Registrars need to reflect on the standards of proof that they currently use to support claims for business performance improvement from the application of the ISO 9000 standards

The textbook as classroom context variable

To explore the role of the textbook as a context variable in process—product relationships, data on teaching practices and learning outcomes from the IEA Classroom Environment Study in The Netherlands were used. The sample consisted of 50 secondary school mathematics classes and their teachers. Three textbooks were represented in the sample. Data collection included systematic observation of lessons and administration of tests and questionnaires to students and teachers. Nine teaching practices analogous to the distinguishing features of the textbooks were identified, and data relating to these practices were analysed. Four of the teaching practices occurred to different degrees in the three groups of textbook users. The correlations with two learning outcomes in different groups of textbook users were significantly different for 5 of the 18 cases. These results suggest that the textbook is an important context variable