Multi-Criteria Query Optimization in the Presence of Result Size and Quality Tradeoffs

In this paper, we present novel multi-criteria query optimization techniques for performing query optimization in databases, such as multimedia and web databases, which rely on imperfect access mechanisms and top-k predicates. We present an optimization model that (1) takes into account different binding patterns associated with query predicates, (2) considers the variations in the expected query result sizes as a function of query execution plans, and (3) considers the expected result qualities of the execution orders. We address the complexity and the well-known NP-complete nature of the query optimization problem by adaptively reducing the granularity of the search space. For this purpose, unlike the data histograms which capture the data distribution, we propose opt-histograms that capture the distribution of sub-query-plan values over many optimization tasks.     

Solidification and stabilization of asbestos waste from an automobile brake manufacturing facility using cement

Currently, the generated brake lining waste dust, which contains asbestos as its major component, is disposed of into a secure landfill without any additional treatment. As an alternative to this, solidification/stabilization (S/S) disposal of the dust was investigated using Portland cement alone and Portland cement mixed with activated carbon (AC), as the binders. Toxicity Characteristics Leaching Procedure (TCLP) results on the solidified matrix showed that cement was able to immobilize the heavy metals, Ba, Zn, Cr, Pb, Cu and Fe, to within the limits set by the US EPA for TCLP. Addition of AC to the cement reduced the leaching of heavy metals by an additional 4-24% compared to cement alone. The pH of the TCLP leachate extracted from virgin cement, and from dust treated with cement with or without AC was found to increase to 10.9-12.5 as opposed to an initial value of 4.93 for the TCLP extract for the untreated dust. Results of ANS 16.1 (modified) leach protocol revealed that Ba in cement-treated samples showed the highest leach rate, followed by Zn, Pb, Cr, Cu and Fe. The leach rate of heavy metals decreased with progress in time. Cement mixed with AC exhibited similar leach characteristics, however, the leach rate was lower. The linear relationship between the cumulative fraction leached (CFL) and the square root of leaching time in all cement-based samples indicate that a diffusional process is the controlling transport mechanism for the leaching of the heavy metals. The obtained Leachability Indices (L(i)) of 7.6-9.1 and 8.3-9.5 for cement and cement with AC, respectively, were low but exceeded the guidance value of 6, which clearly indicates that all the heavy metals studied are retained well within solid matrices. Cement-based S/S hardening times increased from 30 to 96 h as the dust content increased from 40 to 70 wt.%. The resulting solid matrices exhibited a compressive strength ranging from 1 to 12 MPa, which was well above the specified limit of 414 kPa for such matrices. An economic analysis indicates that the disposal costs for the dust in the only available secure landfill would increase by 40.3% if one were to go for the cement S/S option. Addition of AC to the cement would escalate this by an additional 43.8%. Although the S/S of brake lining dust using cement effectively immobilized the heavy metals of concern, cost considerations may hinder the commercial adaptation of this technique for waste disposal unless new regulatory demands are implemented.     

Mechanism and evaluation in electroinitiated copolymerization coatings of acrylonitrile and acrylic acid

Adherent films of copolymers on different metal surfaces were formed by an electrolytically initiated polymerization of acrylonitrile (AN) and acrylic acid (AA) in 0.05N H₂SO₄ aqueous solution. The electrolysis was carried out under a constant current. Hydrogen overvoltages for five different metals used as the cathode were measured in order to interpret the nature and quality of the coating. Solutions containing varying volume fractions of AN and containing different electrolytes gave rise to coatings of varying film thickness. Based on the analyses of copolymer compositions, it is believed that the polymer was formed at the cathode by a free-radical propagation mechanism. The film hardness and the adhesion between the polymer and the metal surface were measured with an Arco microknife. Furthermore, the scanning electron microscope (SEM) was used to examine the structure of the film surface and cross section. The corrosion rates of the coated and uncoated metals in substitute ocean water were also measured for purposes of evaluation of the coatings.     

Photoelectrochemical solar cell studies on electroplated cuprous oxide thin films

Cuprous oxide (Cu₂O) is an interesting p-type semiconductor with a band gap of 2 eV suitable for solar cell applications. Deposition of Cu₂O thin films by electrodeposition from aqueous solutions is a low temperature and inexpensive technique. in the present work, Cu₂O thin films were cathodically deposited on Cu and tin oxide coated glass substrates by the cathodic reduction of copper (II) lactate solution. The optimized deposition conditions to synthesize cuprous oxide thin films were experimentally identified as; Deposition potential: −0.555 V versus SCE, pH: 9.0 ± 0.1, Bath temperature: 70^∘C. X-ray diffraction studies revealed the formation of single phase cubic Cu₂O films. The effect of annealing on the structure and morphology of Cu₂O thin films are studied. The dielectric susceptibility, optical conductivity and packing density are evaluated. Photoelectrochemical solar cells based on p-Cu₂O films are constructed. Spectral response studies indicate a peak in photo current density around 600 nm corresponding to the band gap of Cu₂O thin films. The effects of annealing, chemical etching and photo etching on the solar cell parameters are studied.     

Electrochemical synthesis and characterization of zinc selenide thin films

In this work, electrochemical deposition and characterization of zinc selenide (ZnSe) thin films is reported. ZnSe thin films were deposited onto tin oxide (SnO₂) coated conducting glass substrates from an aqueous solution bath containing ZnSO₄ and SeO₂. The effect of deposition parameters such as bath temperature, deposition time and electrolyte composition on the properties of the ZnSe films has been studied. Cyclic Voltammetric studies were carried out to optimize the deposition potential for the co-deposition of Zn and Se. Deposited ZnSe films have been characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscope (SEM) and optical techniques for their structural, compositional and optical properties and the results are discussed.     

Assessment of crtRB1 Polymorphism Associated with Increased β-Carotene Content in Maize (Zea mays L.) Seeds

Breeding for increasing β-carotene levels in maize (Zea mays L.) kernel aims to address the dietary vitamin A deficiency. Due to 3’TE polymorphism, the crtRB1gene (that encodes β -carotene hydroxylase 1) exists in the three allelic forms, viz., 3’TE allele 1 (termed favorable allele, for it favors higher β-carotene accumulation in kernels), 3’TE allele 2 and 3’TE allele 3 (both termed unfavorable alleles, for they do not favor β-carotene accumulation). Here, we aimed to identify maize lines with favorable allele. First, 3’TE polymorphism assay in 210 inbreds revealed that only “UMI 176” had the favorable allele while the rest had the unfavorable alleles, confirming the previous finding that favorable allele is rare in frequency. Second, β-carotene content analysis in 24 inbreds revealed that it varied from 4.5 to 7.92 (μg/g), 0.23 to 2, and 0.42 to 4.22 for lines with allele 1, 2, and 3 respectively, corroborating the previous findings that the presence of favorable allele correlates with higher β-carotene content. In summary, UMI 176 has the favorable allele and had the highest amount of β-carotene content (7.92 μg/g), indicating that it is a promising donor line that can be utilized in β-carotene biofortification breeding.