Application of Risk Analysis and Simulation for Nuclear Refurbishment Projects

In this thesis, a planning methodology is proposed for nuclear refurbishment projects as a means to address project objectives, influential factors, constraints, and their interdependencies to attain a more reliable estimate of project outcomes. As part of this process, the uncertainty and impact of risk events around project outcomes are taken into account. The proposed methodology consists of two stages. The first stage addresses the impact of commonly identified risks (i.e., Type I risks) and uncertainty on the project outcomes. Also, the interdependence among shift schedule, productivity rate, calendar duration, and risk registers within each identified what-if scenario has been taken into account. The confidence in achieving each of the what-if scenarios is determined using Monte Carlo simulation and a 3-dimensional joint confidence limit model. Based on the simulation results, the deterministic values of the selected project outcomes and the mean values of the resultant distributions are driven primarily by uncertainty, and the distribution tails represent the impact of materialized risks. Also, the probability of failure for each project outcome is less than the joint probability of failure for multiple outcomes. In the second stage of the methodology, the resultant distribution tails (attained from the previous stage) are explored by primarily assessing the impact of outliers (i.e., Type II risks) on project outcomes. Although outliers are typically considered rare events with extreme impacts, the scale and complexity of megaprojects such as refurbishment of nuclear reactors leads to a more frequent occurrence of such events. The applied methodology stems from the reliability analysis approach used to partially justify soft error within integrated circuits due to the observed commonalities such as scale and complexity. A combination of probability theory, Critical Path Method, and Monte Carlo simulation is used to assess the true probability of occurrence for such events. Based on the simulation results, the outliers should be acknowledged and incorporated in the risk management plan of large-scale and complex ventures such as megaprojects. The proposed methodology is validated via Delphi and sensitivity analysis, and functional demonstration using information from an actual multi-billion dollar nuclear refurbishment project and a unique full-scale mock-up of the reactor’s fuel channels and feeders

Setting Target Rates for Construction Activity Analysis Categories

This thesis is focused on increasing productive actions in construction by a procedure known as Activity Analysis. Activity Analysis is a continuous productivity improvement tool for identifying barriers to site productivity with the goal of decreasing them and thereby increasing the direct work rate. A preceding study validated this approach, however it had two limitations. No reevaluation was conducted on projects in Canada by the authors, and not enough resources or data were available to understand behaviour of the activity rates in absolute value terms across many projects. Based on three case studies and data collected over 17 days by the author and a colleague, Activity Analysis was validated as being applicable in Canadian conditions. A desired value, known as a target rate, was then studied in order to be able to set expectations with respect to the productivity to be achieved in each cycle. The premise behind setting a “target rate” is that 100% direct work is neither possible nor desirable, since some time must always be spent on communications and planning. However, a higher direct work rate is generally better than a lower rate. Thus, a target rate is needed. A mathematical model called ANFIS was developed as a means of setting the desired level of activities. Through consideration of a variety of factors that affect labour productivity, the developed model was trained based on 65 data points. The model was found to be easy to use and flexible enough to be appropriate for all of the factors considered. Based on the data points available from 5 different past projects and 3 recent projects and the experience associated with these projects, three additional methods of defining the target rate were developed. The impact of these results is that companies now have appropriate methods and an initial data set for industrial construction in order to establish target rates for direct work and supporting activities. This should help reduce project costs and improve productivity

A Risk Based Approach to Module Tolerance Specification

This research investigates tolerance strategies for modular systems on a project specific basis. The objective of the proposed research is to form a guideline for optimizing the construction costs/risks with the aim of developing an optimal design of resilient modular systems. The procedures for achieving the research objective included: (a) development of 3D structural analysis models of the modules, (b) strength/stability investigation of the structure, (c) developing the fabrication cost function, (e) checking elastic and inelastic distortion, and (f) constructing the site-fit risk functions. The total site-fit risk function minimizes the cost/risk associated with fabrication, transportation; alignment, rework, and safety, while maximizing stiffness in terms of story drift values for site re-alignment and fitting alternatives. The fabrication cost function was developed by collecting 61 data points for the investigated module chassis using the SAP2000 software while reducing the initial section sizes, in addition to the fabrication costs at each step (61 steps). With the reduction of the structural reinforcement, story drift values increase, therefore there will be a larger distortion in the module. This generic module design procedure models a trade-off between the amount of reinforcement and expected need for significant field alterations. Structural design software packages such as SAP2000, AutoCAD, and Autodesk were used in order to model and test the module chassis. This research hypothesizes that the influential factors in the site-fit risk functions are respectively: fabrication, transportation, alignment, safety, and rework costs/risks. In addition, the site-fit risk function provides a theoretical range of possible solutions for the construction industry. The maximum allowable modular out-of-tolerance value, which requires the minimum amount of cost with respect to the defined function, can be configured using this methodology. This research concludes that over-reinforced or lightly-reinforced designs are not the best solution for mitigating risks, and reducing costs. For this reason the site-fit risk function will provide a range of pareto-optimal building solutions with respect to the fabrication, transportation, safety, alignment, and rework costs/risks

Trace Detection of Diphenhydramine by Adsorption on a Microelectrode at Flow Injection System by Fast Fourier Transform Continuous Cyclic Voltammetry

A continuous cyclic voltammetric study of diphenhydramine at gold micro electrode was carried out. Some investigations were also done to find the effects of various parameters on the sensitivity of the proposed method. The experiments were performed under the following conditions: pH = 2, the scan rate = 40 V/ s (v), accumulation potential = 500 mV (E), and accumulation time = 0.2 s (t). The drug in phosphate buffer (pH = 2.0) is adsorbed at optimized condition on the surface of electrode, giving rise to change in the current of well-defined oxidation peak of gold in the flow injection system. The proposed detection method is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. Signal-to-noise ratio has significantly increased by application of discrete Fast Fourier Transform (FFT) method, background subtraction and twodimensional integration of the electrode response over a selected potential range and time window. The linear concentration range was from 4.0 × 10–7 to 1.0 × 10–11 mol dm–3 (r = 0.9987) with a limit of detection and quantitation 5 × 10–12 and 4 × 10–11 mol dm–3, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay diphenhydramine in tablets

Associations of symptomatic knee OA with histopathologic features in subchondral bone

© 2019, American College of Rheumatology Objective: Subchondral bone and the osteochondral junction are thought to contribute to osteoarthritis (OA) knee pain. We undertook this study to identify osteochondral pathologies specifically associated with symptomatic human knee OA. Methods: Medial tibial plateau samples from 2 groups of subjects (n = 31 per group) were matched for macroscopic chondropathy scores. The symptomatic chondropathy group had undergone total knee replacement for OA knee pain, at which time specimens of the medial tibial plateau were obtained. The asymptomatic chondropathy group included subjects who died of unrelated illness (specimens were obtained at postmortem examination) and who had not previously sought help for knee pain. OA histopathology, immunoreactivity for nerve growth factor (NGF) and CD68 (macrophages), tartrate-resistant acid phosphatase–positive subchondral osteoclasts, and synovitis were compared between groups. Results: Mankin scores, subchondral bone density, and subchondral CD68-immunoreactive macrophage infiltration were similar between the 2 groups. NGF-like immunoreactivity was found in subchondral mononuclear cells and osteoclasts, as well as in chondrocytes. NGF in osteochondral channels and osteoclast densities in subchondral bone were higher in the symptomatic chondropathy group than in the asymptomatic chondropathy group (P < 0.01 and P = 0.02, respectively), as were synovitis scores (P < 0.01). Osteochondral pathology was not significantly associated with synovitis score. The differences in NGF expression and in osteoclast density remained significant after adjustment for age and synovitis score (P = 0.01 and P = 0.04, respectively). Osteochondral NGF and osteoclast densities, together with synovitis scores, explained ~28% of sample allocation to symptomatic or asymptomatic groups. Conclusion: Subchondral pathology was associated with symptomatic knee OA, independent of chondropathy and synovitis. Increased NGF expression in osteochondral channels and increased osteoclast density appear to be key features associated with bone pain in knee OA

Distribution of Total Volatile Organic Compounds at taxi drivers in Tehran

Air pollution is currently the most serious environmental health threat worldwide. Volatile Organic Compounds (VOC) are considered as the main effective factors in causing air pollution. Vehicles are among the major sources which emit these compounds, so it seems that automobiles’ microenvironment is one of the places where people are exposed to high concentration of VOC. Evaluating the exposure amount of Total Volatile Organic Compounds (TVOC) can indeed be used as an indicator to estimate the amount of exposure to every individual VOC. This study was conducted on the concentration of TVOC inside Tehran taxies for a period of one year. For this purpose, a real time instrument equipped with photo-ionization detector (PID) was used. Consequently, the highest and the lowest measured TVOC in taxies equaled 3.33 ppm and 0.72 ppm, respectively. In addition, the arithmetic mean of TVOC concentration was 1.77±0.53 ppm inside the examined taxies. In this study, the parameters like measurement time, climate and vehicle conditions were found to have significant effect on the amount of exposure to TVOC

Evaluation of factors influencing recovery of herbicide MCPA from drinking water

ABSTRACT: Many modern analytical methods deal with the trace-level determination of compounds of interest in highly comple

Association of subchondral bone marrow lesion localization with weight-bearing pain in people with knee osteoarthritis: data from the Osteoarthritis Initiative

© 2021, The Author(s). Background: Subchondral bone marrow lesions (BMLs) detected on MRI in knee osteoarthritis (OA) are associated with knee pain. The prevalence and progression of subchondral BMLs are increased by mechanical knee load. However, associations of subchondral BML location with weight-bearing knee pain are currently unknown. In this study, we aim to demonstrate associations of subchondral BML location and size with weight-bearing knee pain in knee OA. Methods: We analyzed 1412 and 582 varus knees from cross-sectional and longitudinal Osteoarthritis Initiative datasets, respectively. BML scores were semi-quantitatively analyzed with the MRI Osteoarthritis Knee Score for 4 subchondral regions (median and lateral femorotibial, medial and lateral patellofemoral) and subspinous region. Weight-bearing and non-weight-bearing pain scores were derived from WOMAC pain items. Correlation and negative binomial regression models were used for analysis of associations between the BML scores and pain at baseline and changes in the BML scores and changes in pain after 24-month follow-up. Results: Greater BML scores at medial femorotibial and lateral patellofemoral compartments were associated with greater weight-bearing pain scores, and statistical significance was retained after adjusting for BML scores at the other 4 joint compartments and other OA features, as well as for non-weight-bearing pain, age, sex, and body mass index (BMI) (medial femorotibial; B = 0.08, p = 0.02. patellofemoral; B = 0.13, p = 0.01). Subanalysis revealed that greater medial femorotibial BML scores were associated with greater pain on walking and standing (B = 0.11, p = 0.01, and B = 0.10, p = 0.04, respectively). Lateral patellofemoral BML scores were associated with pain on climbing, respectively (B = 0.14, p = 0.02). Increases or decreases over 24 months in BML score in the medial femorotibial compartment were significantly associated with increases or decreases in weight-bearing pain severity after adjusting for non-weight-bearing pain, age, sex, baseline weight-bearing pain, BMI, and BML at the other 4 joint compartments (B = 0.10, p = 0.01). Conclusions: Subchondral BML size at the medial femorotibial joint compartment was specifically associated with the severity and the change in weight-bearing pain, independent of non-weight-bearing pain, in knee OA. Specific associations of weight-bearing pain with subchondral BMLs in weight-bearing compartments of the knee indicate that BMLs in subchondral bone contribute to biomechanically induced OA pain