Architecture of the Mobile Environment for Intelligent Genetic Search and Proxy Caching

As the number of documents and servers on Internet grows with the enormous speed, it becomes necessary to design efficient algorithms and tools for search and retrieval of documents. Also, the number of accesses to servers on Internet constantly grows. Congestion of servers and links can be alleviated using proxy caches. Latency on Web can be reduced using prefetching and caching. Efficient search of documents can be done with improved genetic algorithm that exploits the principles of temporal and spatial locality. Mobile agents can be used to optimize network traffic for distributed applications. This paper describes several existing solutions to the problem and discusses the implementation of Java distributed object application for experimenting with genetic search and proxy caching algorithms for Internet.     

Mercury transport and fate in the Gulf of Trieste (Northern Adriatic)—a two-dimensional modelling approach

The Gulf of Trieste is subject to mercury pollution from the So a River which drains polluted sediments from the region of a former mercury mine in Idrija, Slovenia. This has resulted in elevated mercury levels in some marine organisms. Due to a concern for human health, a study has been undertaken to predict mercury contamination trends through the use of a field program and a mathematical model. An annual mercury mass balance of the Gulf is presented first in the paper. This confirms the assumption of the importance of the particulate mercury loads and sedimentation in the mercury cycle. A two-dimensional (2D) advection-dispersion model for non-conservative pollutants which simulates mercury cycling in the Gulf, is then described. This model incorporates the results of a 2D steady-state, primarily wind-driven hydrodynamic model and a 2D sediment transport model. A coupling of the submodels and verification of the integral mercury cycling model are also presented.     

IFC-Based Framework for Evaluating Total Performance of Building Envelopes

Evaluating the overall performance of buildings has emerged as a trend in building engineering in recent years. Several programs that evaluate building performance have been developed or are being developed in different regions of the world. The building envelope performance assessment tool was initiated at Concordia University based on the feedback received from manufacturers. After briefly introducing the development of the tool, this paper presents an integrated framework which applies information technology and the international standard Industry Foundation Classes (IFC) to ensure that the building envelope satisfies energy requirements as well as other requirements such as moisture and thermal performance, concurrently. The framework is designed to extract geometric and material layers’ data of a house from computer-aided design (CAD) drawings in IFC data model, link to performance evaluation applications, such as HOT2000 and MOIST3.0, and compare evaluation results with a set of criteria. To demonstrate the functionalities of this framework, a prototype system has been developed including a preprocessor that imports the building model from an IFC-compatible CAD application, an application integrator, and a postprocessor. Finally, a case study, which aims to validate this prototype system, is discussed in detail.     

Operation of the ATLAS muon drift-tube chambers at high background rates and in magnetic fields

In the ATLAS muon spectrometer, large drift-tube chambers are used for precision tracking. The chambers will be operated at a high neutron and /spl gamma/ background resulting in count rates of up to 500 Hz cm/sup -2/ corresponding to 300 kHz per tube. The spatial resolution of the drift tubes is degraded from 82 /spl mu/m without background to 108 /spl mu/m at 500 Hz cm/sup -2/ background count rate. Due to afterpulsing in the Ar/CO/sub 2/ gas mixture used in the drift tubes, ionizing radiation causes more than one hit in a tube within the maximum drift time of about 800 ns which is expected for magnetic field strengths around 1.2 T. In order to limit the count rate, the drift tubes are read out with an artificial dead time of 790 ns which causes an efficiency loss of 23% at a rate of 300 kHz per tube. The space-to-drift-time relationship of the tubes varies with background rate, temperature, and magnetic field strength. The mean magnetic field strength in a muon chamber is 0.4 T on the average, but may vary by up to 0.4 T within a chamber. The space-to-drift-time relationship must therefore be determined in short time intervals with an accuracy better than 20 /spl mu/m using muon tracks and applying corrections for measured magnetic field variations.     

Toxicity assessment of heavy metal mixtures by Lemna minor L

The discharge of untreated electroplating wastewaters directly into the environment is a certain source of heavy metals in surface waters. Even though heavy metal discharge is regulated by environmental laws many small-scale electroplating facilities do not apply adequate protective measures. Electroplating wastewaters contain large amounts of various heavy metals (the composition depending on the facility) and the pH value often bellow 2. Such pollution diminishes the biodiversity of aquatic ecosystems and also endangers human health. The aim of our study was to observe/measure the toxic effects induced by a mixture of seven heavy metals on a bioindicator species Lemna minor L. Since artificial laboratory metal mixtures cannot entirely predict behaviour of metal mixtures nor provide us with informations relating to the specific conditions in the realistic environment we have used an actual electroplating wastewater sample discharged from a small electroplating facility. In order to obtain three more samples with the same composition of heavy metals but at different concentrations, the original electroplating wastewater sample has undergone a purification process. The purification process used was developed by Orescanin et al. [Orescanin V, Mikeli? L, Luli? S, Nad K, Rubci? M, Pavlovi? G. Purification of electroplating wastewaters utilizing waste by-product ferrous sulphate and wood fly ash. J Environ Sci Health A 2004; 39 (9): 2437-2446.] in order to remove the heavy metals and adjust the pH value to acceptable values for discharge into the environment. Studies involving plants and multielemental waters are very rare because of the difficulty in explaining interactions of the combined toxicities. Regardless of the complexity in interpretation, Lemna bioassay can be efficiently used to assess combined effects of multimetal samples. Such realistic samples should not be avoided because they can provide us with a wide range of information which can help explain many different interactions of metals on plant growth and metabolism. In this study we have primarily evaluated classical toxicity endpoints (relative growth rate, Nfronds/Ncolonies ratio, dry to fresh weight ratio and frond area) and measured guaiacol peroxidase (GPX) activity as early indicator of oxidative stress. Also, we have measured metal accumulation in plants treated with waste ash water sample with EDXRF analysis and have used toxic unit (TU) approach to predict which metal will contribute the most to the general toxicity of the tested samples.     

Two Dimensional Heavy Metal Transport Model for Natural Watercourses

This work presents the development and calibration of a two‐dimensional (depth‐averaged) river flow, sediment transport and heavy metal transport model in natural watercourses. Because heavy metals occur in dissolved and adsorbed phases, implementing the active‐layer concept for sediment transport computation enabled the development of a heavy metal transport model that accounts for pollutant moving in dissolved phase, adsorbed on suspended sediment, adsorbed on bed‐load, deposited in the active‐layer of the river bed or adsorbed on sediment in deeper strata. The proposed concept also enables the modelling of pollutant exchange processes using accessible sediment particle surface area for suspended and bed sediment separately. The presented heavy metal transport model is able to manage sediment mixtures found in natural watercourses using an arbitrary number of sediment size‐classes, distinguishing in this way smaller size‐classes that engage in interaction with the pollutant. Using field measurements for a reach of the Danube River, simulations were conducted for water flow, sediment transport and heavy metal transport. While some discrepancies between measured and computed values for pollutant concentrations were observed, the model reproduced the water and sediment contamination quite reasonably with acceptable mass conservation errors. The simulations also gave an insight in the general behaviour of the monitored heavy metals in the considered river reach. Therefore, it can be concluded that the developed model is suitable for simulating complex flow, sediment transport and heavy metal transport conditions in natural watercourses. Copyright © 2015 John Wiley & Sons, Ltd.     

Target-atom inner-shell vacancy distributions created in collisions with heavy ion projectiles

A model of the evolution of Cu atom inner-shell electron configurations was developed in order to establish the relationship between the original populations created in K-vacancy producing collisions with fast heavy-ion projectiles and those that exist at the time of Cu K and Kβ X-ray emission. The model takes into account multi-step vacancy rearrangement processes that may occur prior to K X-ray emission. An iterative procedure is employed in which a set of trial parameters that define the original inner-shell population distributions are varied to obtain satisfactory agreement of the calculated K satellite relative intensities and energies, as well as the overall intensity ratio of Kβ satellites to K satellites, with the experimental data. In addition to deducing the properties of the original L- and M-shell population distribution, this procedure also provides the average value of the fluorescence yield for conversion between X-ray and K-vacancy production cross sections.     

Influence of Obstacles on the Development of Gravity Current Prior to Backdraft

The phenomenon of backdraft is closely linked to the formation of a flammable region due to the mixing process between the unburned gases accumulated in the compartment and the fresh air entering the compartment through a recently created opening. The flow of incoming fresh air is called the gravity current. Gravity current prior to backdraft has already been studied, Fleischmann (1993, Backdraft phenomena, NIST-GCR-94-646. University of California, Berkeley) and Fleischmann (1999, Numerical and experimental gravity currents related to backdrafts, Fire Safety Journal); Weng et al. (2002, Exp Fluids 33:398–404), but all simulations and experiments found in the current literature are systematically based on a perfectly regular volume, usually parallelipedic in shape, without any piece of furniture or equipment in the compartment. Yet, various obstacles are normally found in real compartments and the question is whether they affect the gravity current velocity and the level of mixing between fresh and vitiated gases. In the work reported here, gravity current prior to backdraft in compartment with obstacles is investigated by means of three-dimensional CFD numerical simulations. These simulations use as a reference case the backdraft experiment test carried out by Gojkovic (2000, Initial Backdraft. Department of Fire Safety Engineering, Lunds Tekniska Högskola Universitet, Report 3121). The Froude number, the transit time and the ignition time are obtained from the computations and compared to the tests in order to validate the model.     

Investigation of Growth and Shrinkage Mechanisms in Vapor-Induced Expansion of Extrusion-Cooked Corn Grits

The development of expansion models with good predicting capabilities requires experimental data and a more fundamental understanding of the vapor-induced expansion behavior in extrusion cooking. In this study, we used a conventional and also a high-speed camera to observe the radial and axial expansion behavior of extrusion-cooked corn grits. Image processing was performed with an automated evaluation code. The experimental setup consisted of a novel high-speed extruder, which enabled the determination of the influence of high screw speeds of up to 1,200 rpm on extrudate growth and shrinkage. In addition to optical measurement of the expansion, moisture content and temperature development during growth and shrinkage were determined. Three distinct stages of expansion were observed: extrudate growth, short-term shrinkage, and long-term shrinkage. The initial extrudate growth rate fitted well with a linear regression. Especially the second stage of shrinkage occurring in a time range of 24 h after the experiment showed that shrinkage is often underestimated in existing models. Furthermore, total shrinkage increased at higher screw speeds. The data obtained deliver new insight into expansion phenomena and can support the development of predicting models.     

Terahertz Spectroscopy of Biochars and Related Aromatic Compounds

A recent application of terahertz spectroscopy is to biochar, the agricultural charcoal produced by pyrolysis of various organic materials. Biochars simultaneously improve soil fertility and assist in carbon sequestration. Terahertz spectroscopy allows different biochars to be distinguished. However, the origin of the absorption features observed has not been clear. Given that biochar-based fertilizers are rich in aromatic compounds, we have investigated simple aromatic compounds as an approach to unravelling the complex biochar spectrum.