Solidification/Stabilization of Hazardous Wastes Containing Metals and Organic Contaminants

The potential of solidification/stabilization (S/S) technology for the safe disposal of hazardous wastes has wide spread recognition. The purpose of this study was to investigate the effectiveness of portland cement-based S/S technology for the safe disposal of hazardous wastes containing toxic metals and organic contaminants. As hazardous wastes, metal enriched mining residue, adsorbable organic halogens (AOX) containing pulp and paper sludge, and polychlorinated biphenyl (PCB) oil-contaminated soil were used. For S/S of waste, portland cement as a binding agent was mixed with wastes at different ratios. For initial waste characterization, contaminant concentrations and some physical waste characteristics such as particle-size distribution, Atterberg limits, specific gravity, and moisture content yielding the maximum compacted dry density were determined. Waste and cement mixtures were cured for 28 days after compacting the desired waste-cement mixtures at their predetermined optimum moisture contents yielding the corresponding maximum dry densities in cylindrical molds having a height of 71 mm and a diameter of 36 mm. At the end of the 28-day cure period, unconfined compressive strength and hydraulic conductivity measurements were conducted on the solidified samples. Subsequently, solidified samples were crushed for fractionation into two different aggregate sizes (between 1–2 and >2 mm) and subjected to the U.S. Environmental Protection Agency Toxicity Characteristic Leaching Procedure (TCLP). The effectiveness of S/S was assessed by comparing the chemical composition of leachates obtained from TCLP tests of untreated and treated, i.e., S/S waste samples, and comparing values of strength and hydraulic conductivity of solidified waste samples with regulatory requirements. For mining waste, effective application of S/S was achieved for most cases. AOX containing sludge yielded acceptable results in terms of strength and hydraulic conductivity but leachate AOX concentrations were above regulatory levels. The effectiveness of S/S for coarse textured-soils contaminated with a PCB oil was not satisfactory, especially at a cement:soil ratio less than 35%.     

Model selection in omnivariate decision trees using Structural Risk Minimization

As opposed to trees that use a single type of decision node, an omnivariate decision tree contains nodes of different types. We propose to use Structural Risk Minimization (SRM) to choose between node types in omnivariate decision tree construction to match the complexity of a node to the complexity of the data reaching that node. In order to apply SRM for model selection, one needs the VC-dimension of the candidate models. In this paper, we first derive the VC-dimension of the univariate model, and estimate the VC-dimension of all three models (univariate, linear multivariate or quadratic multivariate) experimentally. Second, we compare SRM with other model selection techniques including Akaike’s Information Criterion (AIC), Bayesian Information Criterion (BIC) and cross-validation (CV) on standard datasets from the UCI and Delve repositories. We see that SRM induces omnivariate trees that have a small percentage of multivariate nodes close to the root and they generalize more or at least as accurately as those constructed using other model selection techniques.     

The mild oxidation of three Tertiary lignites

Three Tertiary lignites have been oxidized with nitrobenzene and sodium hydroxide at 200 °C in a sealed tube. A scheme of extraction has been used to separate the oxidation products and the resulting solutions have been characterized by their infra-red and ultraviolet absorption spectra and by spot tests. The products contain phenolic hydroxyl and carbonyl — rather than carboxyl — groups. Some of the solutions have been reduced and their n.m.r. spectra recorded. The oxidation procedure shows promise as a method of determining the structure of lignites.     

Software defect prediction using Bayesian networks

There are lots of different software metrics discovered and used for defect prediction in the literature. Instead of dealing with so many metrics, it would be practical and easy if we could determine the set of metrics that are most important and focus on them more to predict defectiveness. We use Bayesian networks to determine the probabilistic influential relationships among software metrics and defect proneness. In addition to the metrics used in Promise data repository, we define two more metrics, i.e. NOD for the number of developers and LOCQ for the source code quality. We extract these metrics by inspecting the source code repositories of the selected Promise data repository data sets. At the end of our modeling, we learn the marginal defect proneness probability of the whole software system, the set of most effective metrics, and the influential relationships among metrics and defectiveness. Our experiments on nine open source Promise data repository data sets show that response for class (RFC), lines of code (LOC), and lack of coding quality (LOCQ) are the most effective metrics whereas coupling between objects (CBO), weighted method per class (WMC), and lack of cohesion of methods (LCOM) are less effective metrics on defect proneness. Furthermore, number of children (NOC) and depth of inheritance tree (DIT) have very limited effect and are untrustworthy. On the other hand, based on the experiments on Poi, Tomcat, and Xalan data sets, we observe that there is a positive correlation between the number of developers (NOD) and the level of defectiveness. However, further investigation involving a greater number of projects is needed to confirm our findings.     

Pre-stressed adhesive strap joints for thick composite sandwich structures

A simple but effective design to improve the strength of thick adhesive composite strap joints is validated with experiment and finite element method. The strap joint under investigation, with a particular application to naval ship structures, consists of two thick woven E-glass/vinyl ester laminates joined together with two steel doublers. Longitudinal tensile loads are applied to the joints, resulting in large concentrated shear and peel stresses near the free edges of bondlines. The new design intends to reduce the adhesive peel stress by application of through-the-thickness compressive pre-stress along the bondline and thus leads to an increase of joint strength. Experiment results show that all the joint failures are delamination of the top layer of the laminated adherends. The test further confirms that joint strength increases significantly by applying the transverse pre-stress. Finite element analysis reveals that the pre-stress can effectively reduce the magnitude even reverse the sign of the peel stress in the adhesive layer and the adherends. Recessing the adhesive leading edge could magnify the pre-stress effect and reduce the adhesive peel stress, but would increase the shear stress. For those composite joints with low transverse interlaminar strength and susceptible to delamination, this simple design/technique can considerably improve their joint strength.     

Agricultural Water Use in Turkey

Abstract

Agriculture is the largest user of water in Turkey with 75 percent of the total consumption. Turkey has developed 50 percent of total irrigable land so far. Water is a limiting factor for agriculture throughout much of Turkey. The amount and distribution of precipitation is quite uneven. Turkey, like many countries today, faces challenges in efficiently developing and managing its agricultural water resources while trying to protect water quality and the environment. However, Turkey has some difficulties and problems on water use for agriculture. Current institutional framework and legal regulation, monitoring and evaluation activities are investigated, and agricultural water use and irrigation development are studied. Problems with the lack of data on environmental effects of irrigation and water pricing are underlined. Evaluation of the current situation ends in the conclusion that Turkey needs a comprehensive monitoring and evaluation system both at basin and scheme level, and rehabilitation of irrigation systems for efficient water use in agriculture.     

Compression of power quality event data using 2D representation

This paper introduces the energy compaction efficiency of a novel two-dimensional (2D) representation for compression of recorded power quality event data. The 2D representation enables to exploit redundancy across vertical samples that correspond to samples which are far from each other in time. In one-dimension (1D), compression algorithms are unable to depict the correlation between such far away samples. However, the 2D representation renders statistically related far away samples near to each other in the vertical dimension, hence several transform domain techniques are able to compress such rendered data efficiently. In this paper, using real life sampled power quality event data, wavelet transform energy compaction efficiencies are compared through a basis restriction error analysis and the results are justified by simple and commercially available 1D and 2D wavelet based coders. The preliminary results indicate that the 2D representation provides a significant energy compaction efficiency.     

Preparation of thin film alloys with electrodeposition from heterotrinuclear M1–M2–M1 complexes (M1: NiII, CuII; M2: CuII, CoII, ZnII, CdII)

M₁ ^II–M₂ ^II–M₁ ^II type linear complexes (where M₁ = Ni²⁺, Cu²⁺ and M₂ = Cu²⁺, Zn²⁺, Co²⁺ and Cd²⁺ were prepared and dissolved in dimethyl sulfoxide. They were then electrodeposited on mild steel surfaces by the use of rotating disc electrodes. The deposition potentials were determined from cyclic voltammetric i-E scans. The metal films deposited on mild steel surfaces were characterized with atomic absorption spectrometer (AAS), X-ray fluorescence (XRF) and ion chromatography (IC) methods. Although the stoichiometric quantity of M₂ metal cation was half of the M₁ metal cation in the complex, the amount of M₂ metal deposited upon the surface was markedly greater. The amount of M₂ ion deposited on the surface was found to increase with the hardness of the ion. The X-ray diffraction (XRD) patterns showed that the excessively deposited metal on the surface was in metallic form as well as alloy. The size of the deposited film particles was investigated by the use of atomic force microscope (AFM) technique and the particles were observed to be bigger than nanoparticle size.