A systematic review of quantitative risk analysis in construction of megaprojects

Mega projects (MP) require efficient management of risks during their construction. Therefore, it is crucial to identify any possible deviations towards meeting their objectives. Such deviation forced MP to be delivered behind schedule and over budget. According references, MP does not require only qualitative analysis but requires an accurate quantitative analysis based on knowledge and practice. Thus, this paper aims to undergo a systematic review of quantitative analysis literature in construction of worldwide MP,with the utmost aim to improve contractors quantitative risk analysis practices in the presence of uncertainty. A time line was produced which shows the process of quantitative risk analysis in this literature including the past six years from 2013 to 2018. This was followed by a critical analysis in order to account for quantitative risk analysis techniques highlighted throughout literature sources. Furthermore, the paper reviews the literature of worldwide mega projects by which quantitative risk analysis process was practiced. It was observed that Monte Carlo analysis technique has succeeded in supporting project managers in allocating deviations in the objectives of MP. The paper adds value to practitioners using the process of quantitative risk analysis as well as contractors working on construction of MP

Partial breaking of global D=4 supersymmetry, constrained superfields, and 3-brane actions

We show that the connection between partial breaking of supersymmetry and nonlinear actions is not accidental and has to do with constraints that lead directly to nonlinear actions of the Born-Infeld type. We develop a constrained superfield approach that gives a universal way of deriving and using these actions. In particular, we find the manifestly supersymmetric form of the action of the 3-brane in 6-dimensional space in terms of N=1 superfields by using the tensor multiplet as a tool. We explain the relation between the Born-Infeld action and the model of partial N=2 supersymmetry breaking by a dual D-term. We represent the Born-Infeld action in a novel form quadratic in the gauge field strengths by introducing two auxiliary complex scalar fields; this makes duality covariance and the connection with the N=1 supersymmetric extension of the action very transparent. We also suggest a general procedure for deriving manifestly duality symmetric actions, explaining in a systematic way relations between previously discussed Lorentz covariant and noncovariant actions.Comment: 28 pages, harvmac. v4: a mistake in eq.(3.24) (pointed out by S. Kuzenko) correcte

Estimating PM 2.5 concentrations in Xi'an City using a generalized additive model with multi-source monitoring data

© 2015 Song et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Particulate matter with an aerodynamic diameter <2.5 μm (PM2.5) represents a severe environmental problem and is of negative impact on human health. Xi'an City, with a population of 6.5 million, is among the highest concentrations of PM2.5 in China. In 2013, in total, there were 191 days in Xi'an City on which PM2.5 concentrations were greater than 100 μg/m3. Recently, a few studies have explored the potential causes of high PM2.5 concentration using remote sensing data such as the MODIS aerosol optical thickness (AOT) product. Linear regression is a commonly used method to find statistical relationships among PM2.5 concentrations and other pollutants, including CO, NO2, SO2, and O3, which can be indicative of emission sources. The relationships of these variables, however, are usually complicated and non-linear. Therefore, a generalized additive model (GAM) is used to estimate the statistical relationships between potential variables and PM2.5 concentrations. This model contains linear functions of SO2 and CO, univariate smoothing non-linear functions of NO2, O3, AOT and temperature, and bivariate smoothing non-linear functions of location and wind variables. The model can explain 69.50% of PM2.5 concentrations, with R2 = 0.691, which improves the result of a stepwise linear regression (R2 = 0.582) by 18.73%. The two most significant variables, CO concentration and AOT, represent 20.65% and 19.54% of the deviance, respectively, while the three other gas-phase concentrations, SO2, NO2, and O3 account for 10.88% of the total deviance. These results show that in Xi'an City, the traffic and other industrial emissions are the primary source of PM2.5. Temperature, location, and wind variables also non-linearly related with PM2.5

Selective photo deposition of Cu onto the surface of monodisperse oleic acid capped TiO2 nanorods probed by FT IR CO adsorption studies

A novel, non aqueous, organometallic route to nanocomposite Cu TiO2 materials is presented. TiO2 nanorods stabilized with oleic acid OLA were used as support for the photo assisted deposition of Cu using the organometallic Cu II precursor [Cu OCH CH3 CH2N CH3 2 2] 1 . The copper precursor 1 penetrates through the shell of OLA and is photo reduced to deposit Cu0 directly at the surface of the TiO2 rods. The obtained Cu decorated nanorods were still soluble in nonpolar organic solvents without change of the morphology of nanorods. The Cu TiO2 colloid was characterized by means of UV VIS, XRD, AAS, and HRTEM. CO adsorption FTIR studies give evidence for Cu0 anchored at the titania surface by a characteristic absorption at 2080 cm 1. Comparative studies of Cu deposition were done using a CuCl2 as simple Cu source which proved, that the concept of organometallic disguise of the metal centre results in a higher reaction rate and the circumvention of non selective reduction, parasitic side reactions and undesired agglomeration of the OLA stabilized titania nanorod

Mesosynthesis of ZnO−Silica Composites for Methanol Nanocatalysis

Methanol catalysis meets chemistry under confined conditions. Methanol is regarded as one of the most important future energy sources. ZnO/Cu composite materials are very effective in heterogeneous catalysis for methanol production due to the so-called strong metal-support interaction effect (SMSI). Therefore, materials of superior structural design potentially representing model systems for heterogeneous catalysis are highly desired. Ultimately, such materials could help to understand the interaction between copper and zinc oxide in more detail than currently possible. We report the preparation of nanocrystalline, size-selected ZnO inside the pore system of ordered mesoporous silica materials. A new, liquid precursor for ZnO is introduced. It is seen that the spatial confinement significantly influences the chemical properties of the precursor as well as determines a hierarchical architecture of the final ZnO/SiO2 nanocomposites. Finally, the ability of the materials to act as model systems in methanol preparation is investigated. The materials are characterized by a variety of techniques including electron microscopy, X-ray scattering, solidstate NMR, EPR, EXAFS, and Raman spectroscopy, and physisorption analysis

WATER HOMEOSTASIS, FRAILTY AND COGNITIVE FUNCTION IN THE NURSING HOME

Objective: - To develop and test a practical clinical method to assess frailty in nursing homes; - To investigate the relationship between cognitive status of the elderly and the balance between water compartments of their body composition. Design and subjects: Cross-sectional study, conducted at two nursing homes in Boston-MA. Methods: Body mass and height (Ht) were evaluated to calculate BMI (body mass index, in Kg/m(2)). The cognitive decline was evaluated based on the scores obtained from the Mini-Mental State Examination (MMSE); The extracellular to total body water ratio (ECW/TBW) was calculated after the analysis of TBW from deuterium and tritium dilution and ECW from bromide dilution. Single-frequency BIA analysis data were investigated for resistance (R) and reactance (Xc), plotted in an R/Ht Xc/Ht graph (vectorial analysis-BIVA). The BIVA results of nursing home residents were compared against the data obtained from the NHANES Ill study. TBW and ECW values were compared with a group of free-living elderly volunteers. Results: The ECW/TBW was significantly higher in nursing home residents than in the free-living individuals. BIVA analysis showed significantly higher Xc/Ht values in the reference subjects. The MMSE did not present a significant correlation with ECW/TBW for either gender. Conclusion: We proposed the ECW/TBW ratio and BIVA as surrogate methods for the clinical assessment of frailty. We tested successfully both approaches with nursing home patients and free-living volunteers and compared them to a national data base. The advent of new, portable instruments will enable field tests to further validate our proposed "Frailty Factor" in future studies. We found no correlation between frailty and cognitive decline in the nursing home.U.S. Department of Agriculture, Agricultural Research Service [58-1950-7-707]U.S. Department of Agriculture, Agricultural Research Servic

Cu/ZnO aggregates in siliceous mesoporous matrices - Development of a new model methanol synthesis catalyst

Copper and zinc were introduced into mesoporous siliceous matrices with the goal of obtaining model methanol synthesis catalysts with intense interaction between copper and the ZnO promoter. The preparation methods included various aqueous routes starting from acetate solutions (into MCM-48) and a route involving an organometallic step thermolysis of a liquid heterocubane of Zn4O4 type ([CH3ZnOCH2CH2OCH3]4) in a wormhole-type silica of 5 nm average pore size followed by aqueous Cu (nitrate) impregnation. The materials were characterized by XRD, nitrogen physisorption, N2O frontal chromatography, TPR, and EXAFS, and their methanol synthesis activity was measured at 493 K and normal pressure. In the aqueous preparations with acetate solutions, excessive formation of silicates (particularly zinc silicate) led to damage of the pore system. A significant delay in Cu reduction was assigned to the influence of micropores formed, together with some copper silicate formation. These samples exhibited poorly accessible Cu surface areas despite small Cu particle sizes indicated by EXAFS and disappointing methanol synthesis activity. In contrast to this, a highly active catalyst was obtained via the heterocubane route that meets industrial standards in terms of reaction rate per Cu surface area. Orientation studies (EXAFS at the CuK and ZnK edges) reflecting a redox behavior of the ZnOx component illustrate the potential of this catalyst type for use in basic studies of the Cu ZnOx interaction in methanol synthesis catalysts

A model utilizing green lean in rice crop supply chain: An investigation in piura, perú

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.This article analyzes the rice sector and the challenges related to the impact generated by production systems, such as greenhouse gas emissions in the natural environment. Previous studies show the application of Green Lean to achieve greater competitiveness and reducing the negative environmental impact. To achieve these objectives, Lean tools are used that improve quality, increase productivity, reduce inventories and costs like the Kaizen method. Therefore, this methodology is proposed through a management model in the sector analyzed to achieve the expected sustainability of the production process