Optical gradation for crushed limestone aggregates

The strength and durability of asphalt pavement is directly affected by the characteristics of its main ingredient, mineral aggregate. Besides material strength, research has shown that mixture properties such as particle shape and mixture gradation have a significant affect on the quality of the asphalt concrete. A standard called Superpave has been developed which sets forth specifications for material selection and methods for measurement of aggregate properties. These standards require monitoring of aggregate properties, particularly gradation. In this dissertation, the feasibility of developing an optically based method for determining aggregate gradation was explored. The physical system primarily consists of a standard monochrome CCD video camera and a computer with a frame grabber board. Software was developed to separate touching or overlapping particles in the image, and to detect the size and shape of each particle. Correlation to estimate each particle\u27s mass and to predict the sieving behavior for crushed limestone aggregates was developed and tested. Laboratory testing demonstrated the ability to measure gradation over a range of particle sizes from 4.75 mm to 25 mm with an accuracy of +/-3 in terms of percent-passing residual when compared with mechanical sieving

The dissolution of magnesium in strong acids and neutral solutions

The increasing demand for magnesium and magnesium- base alloys in the manufacture of aircraft has stimulated a great amount of research into the corrosion characteristics of these materials. The result of such research has been the development of suitable magnesium alloys and protective coatings to retard corrosion. The basic mechanism of the anodic dissolution of metals such as magnesium, zinc, and cadmium in salt solutions is not completely known. Several schools of investigators have proposed different and opposing theories to explain the discrepancies which often arise between coulometer data and the weight loss of metal electrodes in certain salt solutions. The purpose of this investigation was to study the anion effect on the dissolution and disintegration of magnesium. If anion adsorption is important in these processes, then varying the ionic species present should alter kinetic parameters for the dissolution reaction and the apparent valence for the disintegration. To this end, the self-dissolution was studied in hydrochloric, hydrobromic, and hydriodic acids and the anodic dissolution in one normal solutions of potassium sulfate, potassium chloride, potassium nitrate, potassium bromide, and potassium iodide --Introduction, page 1

Finite element analysis for the navier - stokes equations

The finite element method was employed to solve two-dimensional, unsteady, incompressible, viscous fluid flow problems. A practical computation procedure is presented. A complete finite element computer program has been developed. The numerical technique is based upon a general formulation for the Navier-Stokes equations making use of a combined variational principle finite element approach. Solution to the system of algebraic equations is approached by the Gaussian elimination scheme. The time-dependent Navier-Stokes equations are expressed in terras of a stream function equation and a transport equation. A variational functional of the stream function and a pseudo-variational functional of the vorticity of the respective boundary value problem is presented. The pressure distribution and velocity profile are determined from stream function. Two numerical examples are presented and compared with present papers. Some now ideas about the numerical method, obtained through numerical experiments, are presented and discussed

Parton Distributions in the Virtual Photon Target and Factorization Scheme Dependence

We investigate parton distributions in the virtual photon target, both polarized and unpolarized, up to the next-leading order (NLO) in QCD. Parton distributions can be predicted completely up to NLO, but they are factorization-scheme-dependent. We analyze parton distributions in several factorization schemes and discuss their scheme dependence. Particular attentions are paid to the axial anomaly effect on the first moments of the polarized quark parton distributions, and also to the large-$x$ behaviors of polarized and unpolarized parton distributions.Comment: 6 pages, LaTeX, 3 ps figures, uses npb.sty, Contribution to the Zeuthen Workshop on Elementary Particle Theory: Loops and Legs in Quantum Field Theory, Koenigstein-Weissig, Germany, April 200

Behavioral ecology of odometric memories in desert ants: acquisition, retention, and integration

Assuming that the acquisition and retention of memories have costs, properties of memories should fit the functional requirements for the system of memory. Based on a functional analysis of what path integration is meant to do, we predicted that odometric memories in desert ants should show (1) little improvement with repeated training: performance should be as good after one training trial as after six training trials, (2) decay of memory after 24 h, and (3) performance based solely on the most recent outbound trip, with no integration over multiple memories. Desert ants (Cataglyphis fortis) traveled in narrow straight plastic channels to forage for cookie crumbs in a feeder at 6- or 12-m distance. Each ant was tested once by being taken from the feeder and released 2 m from the end of a 32-m channel to run home. The distance at which the ant first turned back (first turn) constituted the data. In acquisition, groups trained one or six times before being tested had unsystematic scatter that did not differ significantly. In retention, ants tested after a 24-h delay showed larger unsystematic scatter than control animals tested after no delay. In integration, ants were trained five times at 6 or 12 m and then tested at 12 or 6 m, respectively. No evidence of integration of multiple odometric memories was found. The results show that the properties of odometric memories are indeed tailored to what the memory system is used fo

Landmarks or panoramas: what do navigating ants attend to for guidance?

<p>Abstract</p> <p>Background</p> <p>Insects are known to rely on terrestrial landmarks for navigation. Landmarks are used to chart a route or pinpoint a goal. The distant panorama, however, is often thought not to guide navigation directly during a familiar journey, but to act as a contextual cue that primes the correct memory of the landmarks.</p> <p>Results</p> <p>We provided <it>Melophorus bagoti </it>ants with a huge artificial landmark located right near the nest entrance to find out whether navigating ants focus on such a prominent visual landmark for homing guidance. When the landmark was displaced by small or large distances, ant routes were affected differently. Certain behaviours appeared inconsistent with the hypothesis that guidance was based on the landmark only. Instead, comparisons of panoramic images recorded on the field, encompassing both landmark and distal panorama, could explain most aspects of the ant behaviours.</p> <p>Conclusion</p> <p>Ants navigating along a familiar route do not focus on obvious landmarks or filter out distal panoramic cues, but appear to be guided by cues covering a large area of their panoramic visual field, including both landmarks and distal panorama. Using panoramic views seems an appropriate strategy to cope with the complexity of natural scenes and the poor resolution of insects' eyes. The ability to isolate landmarks from the rest of a scene may be beyond the capacity of animals that do not possess a dedicated object-perception visual stream like primates.</p

Lab Retriever: a software tool for calculating likelihood ratios incorporating a probability of drop-out for forensic DNA profiles.

BackgroundTechnological advances have enabled the analysis of very small amounts of DNA in forensic cases. However, the DNA profiles from such evidence are frequently incomplete and can contain contributions from multiple individuals. The complexity of such samples confounds the assessment of the statistical weight of such evidence. One approach to account for this uncertainty is to use a likelihood ratio framework to compare the probability of the evidence profile under different scenarios. While researchers favor the likelihood ratio framework, few open-source software solutions with a graphical user interface implementing these calculations are available for practicing forensic scientists.ResultsTo address this need, we developed Lab Retriever, an open-source, freely available program that forensic scientists can use to calculate likelihood ratios for complex DNA profiles. Lab Retriever adds a graphical user interface, written primarily in JavaScript, on top of a C++ implementation of the previously published R code of Balding. We redesigned parts of the original Balding algorithm to improve computational speed. In addition to incorporating a probability of allelic drop-out and other critical parameters, Lab Retriever computes likelihood ratios for hypotheses that can include up to four unknown contributors to a mixed sample. These computations are completed nearly instantaneously on a modern PC or Mac computer.ConclusionsLab Retriever provides a practical software solution to forensic scientists who wish to assess the statistical weight of evidence for complex DNA profiles. Executable versions of the program are freely available for Mac OSX and Windows operating systems

A Roadmap to Sustainability Evaluation: a System Approach from Evaluation Theories

Sustainability evaluation has been widely applied as a tool to manage the relationship between humans and the Earth to avoid human activities that jeopardise the survival of all lives and subsequent implementations have been improving sustainability within certain times and regions. However, consequently, many measures have proved unsustainable outside suitable spatio-temporal scales. While abundant research attempted this issue by developing sustainability frameworks that apply wider systems as evaluation subjects or designing compound indexes, limited work recognise the evaluation nature and analyse from the evaluation theories perspective where the issue could be the consequences of having implicit elements in sustainability evaluation. The issue is attempted following three key research objectives. First, determine the characterisation of evaluation elements by embedding sustainability. Critical literature on evaluation theories, sustainability, and sustainable development (SD) from nearly all fields of study are collected, screened, and analysed. A group of fundamental evaluation elements are summarised to be applicable for this thesis, as a reflection of evaluation theory basis. Proper evaluation should explicitly characterise this group of evaluation elements by decision makers (DMs) and evaluators. Sustainability objectives, where certain criteria should be defined specifying the sustainable state, would influence the characterisation of all evaluation elements. Thus, we state, in practice, that sustainability evaluation is done for a group of necessary conditions towards planet sustainability during which values of key stakeholders including human and non-human lives require demonstration. Second, construct a framework that could develop explicit sustainability evaluation elements with applicable metrics and measurements. Critical literature of sustainability evaluation and key heuristic studies are reviewed and a systemic review of 118 sustainability evaluation empirical studies in the energy sector is conducted. It is confirmed the causes of implicitly unsustainable measures from the evaluation perspective are that sustainability evaluations often implicitly place human values in centre but hold shifting stakeholder stances between human-central or universal values, and many evaluation elements are implicit, especially the evaluation objectives and subject when they are not mutually suitable. Noticing that based on stakeholder connections and criteria of sustainability the evaluation objectives and subject would be explicitly developed, an evaluation framework for sustainability enabling developing of explicit and suitable evaluation elements is constructed, forming a roadmap to sustainability evaluation. The roadmap demonstrates a process of explicitly forming an apposite system for sustainability evaluation objectives that is used as the evaluation subject. The sustainability evaluation framework concludes with metrics of material and energy, structure, and value (MSV). Evaluation results are produced for the apposite system and implementations for the initial system. For cross-system evaluation, a group of suitable, EEV, measurements are proposed. Material metric could be treated as classifying renewable or non-renewable materials. Energy metric could be measured by emergy that traces system energy hierarchy with unified unit. Structure metric could be measured by Shannon entropy. The value measurement could be compensated by human pricing while considering the survival of weak stakeholders. Lastly, the applicability of the roadmap is tested based on the electricity systems of 28 European countries, including the production system and consumption structures. Suggested by the country sustainability objectives of carbon neutrality and targetting energy security, a CO2 sustainable electricity production system targetted for 2005 country sustainability evaluation objectives including 10 electricity production technology subsystems is constructed as a sustainable reference system. Country peer ranking is calculated by individual indexes of energy, entropy, and electricity prices, and compound scores by data envelopment analysis (DEA). It is revealed that the evaluation framework, especially following the proposed protocol, would require mass high-quality data and information for linkages of subsystems, providing directions to refine the framework and evaluation results