Evaluation of FWD software and deflection basin for airport pavements

Falling Weight Deflectometer (FWD) test data are processed by backcalculation software to obtain modulus of layer materials of airport pavements. Currently, several backcalculation software are available. However it is not known which software produces accurate and consistence modulus values. In this study three backcalculation software; namely, BAKFAA, EVERCALC, and MODULUS are evaluated for consistency and accuracy. To examine accuracy, software predicted modulus values are compared to the laboratory tested modulus values of soils, aggregate, and asphalts. Consistency is examined by statistical analysis using three sets of FWD deflection data produced by three loads with magnitudes of 9, 12, and 16 kip at an identical location of an airport pavement. It is shown that EVERCALC software produces more consistent and accurate modulus values than the BAKFAA and MODULUS software. A concern with the available backcalculation software is that their analysis algorithms are based on layered elastic theory with linear materials models. In addition, they consider static loading, which is not the true representation of the dynamic loads applied in a FWD test in the field. To this end, this study performs a dynamic analysis of the FWD deflection basin using a finite element method (FEM) with the consideration of non-linear materials models. Results show that FEM predicted deflections have similar trends of the field measured deflections. However, a number of trial combinations of inputs and FEM models may be required to produce an identical match between the predicted and measured deflections. It is recommended that this approach be the subject of future studies

Evaluating Consistency of Nondestructive Evaluation of Flexible Pavement by GPR and PSPA

Consistency is one of the major issues during the Nondestructive Test & Evaluation (NDT & E) of flexible pavement, i.e., asphalt pavement, by Ground Penetrating Radar (GPR) and Portable Seismic Property Analyzer (PSPA). In some recent nondestructive tests on instrumented pavement section at Milepost (MP) 141 on Interstate-40 (I-40), New Mexico, it is observed that 2-way travel time of GPR signal in unbound layers transmitted by Ground-Coupled Antenna (GCA) varies in different months which leads to different values of layer thickness at a same section and it is believed that the reason is moisture variation. In case of PSPA, tests on Asphalt Concrete (AC) surface show higher level of inconsistency at repeated drops on the same test locations which is believed due to irregular contact between the sensors and surface. To date, unbound materials were collected from the pavement section to measure dielectric constant by Percoemeter in laboratory at varying moisture content. Later, the dielectric constants at varying moisture content are incorporated during the post-processing of GPR data, and thus, the level of consistency is improved. In case of PSPA, quick-setting capping, i.e., a mixture of Plaster of Paris and fine content, is made on AC surface at different locations prior to the tests to ensure firm and smooth contact surfaces. It is observed that consistency of PSPA measurements and interpreted results is improved significantly. Based on the observations, it is recommended to incorporate dielectric constants at varying moisture content to the GPR post-processing. In addition, incorporate capping before a PSPA test on an AC surface

Compare the out-of-sample performance of mean-variance optimization relative to equally weighted or naîve 1/N portfolio

Masteroppgave i finansiering og investering - Nord universitet 202

Simulation Model and Analysis of a Data Warehouse

Data warehouses are large complex systems with many interacting nonlinear components. It is an amalgamation of many different systems and integration of such diverse elements is its primary concern. It is often difficult for a data warehouse manager to predict the performance of the system especially when demand pattern for the required data keeps changing. We have developed a simulation model using ARENA simulation package that will simulate the behavior and performance of a data warehouse system environment based on its overall design. Given such a model, a data warehouse manager can walk through various what-if scenarios and can pinpoint the areas of weaknesses in the system. This visibility could result in improved operational performance in a data warehouse

AC ELECTRIC TRANSPORT PROPERTIES OF Zn SUBSTITUTED Li FERRITES

The electrical transport properties of ZnxLi0.45-x/2Fe2.55-x/2O4 (where, x=0.0, 0.3, 0.5) synthesized by conventional ceramic method have been investigated as a function of Zn content. The X-ray analysis confirms the formation of single phase cubic spinel structure. The ac resistivity and dielectric constant show opposite trend with increase in Zn content. The ac resistivity and dielectric constant of the samples are found to decreases with increase in frequency, exhibiting normal ferromagnetic behaviour. Dielectric constant of the samples decreases rapidly at lower frequencies and slower at higher frequencies which may be due to the Maxwell-Wagner interfacial polarization. The electrical properties can be explained on the basis of Fe2+/Fe3+ ionic concentration

Backcalculated Modulus of Asphalt Concrete

Asphalt Concrete (AC) is considered a spatially homogeneous material when analyzing and designing asphalt pavement. However, the modulus of AC along the wheel path and the middle of the wheel path may not be the same considering the continuous compaction by wheel loading. This study conducted monthly Falling Weight Deflectometer (FWD) tests to determine the AC modulus of a pavement section on Interstate 40 (I-40) in the state of New Mexico, USA from 2013 to 2015. The AC moduli on the wheel path, on the middle of the wheel path, on the shoulder with friction course, and on the shoulder without friction course are determined. It is mentionable that the driving lane and the shoulder have the same geometry, materials, and compaction effort. Results show that the modulus along the wheel path is almost the same as that of along the middle of the wheel path. The shoulder without friction course has a modulus greater than that of the lane AC modulus and the shoulder with the friction course. In addition, FWD backcalculated moduli at different temperatures are compared with the dynamic modulus values of the AC layer. It is found that the dynamic modulus at a loading frequency of 5 Hz is 1.7 to 1.9 times the backcalculated AC modulus

An in situ exploration of subsurface defect migration to a liquid water‐exposed rutile TiO2(110) surface by XPS

The ability of titanium dioixide to split water into OH− and H+ species is heavily dependent on the behaviour of defects in the crystal structure at or near the surface. We present an in situ study of defect migration in rutile TiO2(110) conducted using X‐ray photoelectron spectroscopy (XPS). First, surface and subsurface defects were created in the crystal by argon ion sputtering. Subsequent in situ exposure of the defective crystal to liquid water healed the surface defects, whereas the subsurface remained defective. The sample was then annealed while XPS was used to monitor the concentration of titanium defects. At low annealing temperatures, Ti3+ was observed to migrate from the subsurface to the surface. Further annealing gradually restored the surface and subsurface to the defect‐free Ti4+ form, during which the changes in abundance of Ti1+, Ti2+ and Ti3+ defects are discussed

MicroRNA-208a: a Good Diagnostic Marker and a Predictor of no-Reflow in STEMI Patients Undergoing Primary Percutaneuos Coronary Intervention

MicroRNA-208a is a cardiac specific oligo-nucleotide. We aimed at investigating the ability of microRNA-208a to diagnose myocardial infarction and predict the outcome of primary percutaneuos coronary angiography (PCI). Patients (n = 75) presented by chest pain were recruited into two groups. Group 1 (n = 40) had ST elevation myocardial infarction (STEMI) and underwent primary PCI: 21 patients had sufficient reperfusion and 19 had no-reflow. Group 2 (n = 35) had negative cardiac troponins (cTns). Plasma microRNA-208a expression was assessed using quantitative polymerase chain reaction and patients were followed for occurrence of in-hospital major adverse cardiac events (MACE). MicroRNA-208a could diagnose of MI (AUC of 0.926). After primary PCI, it was superior to cTnT in prediction of no-reflow (AUC difference of 0.231, P = 0.0233) and MACE (AUC difference of 0.367, P = 0.0053). Accordingly, circulating levels of miR-208a can be used as a diagnostic marker of MI and a predictor of no-reflow and in-hospital MACE

Gender as a moderating variable in online misinformation acceptance during COVID-19.

Misinformation remained a critical consideration during the COVID-19 that further cultivated fears leading to strong unrest among the public globally. This study clarifies certain misconceptions related to the pandemic by investigating whether factors such as altruism, entertainment, information-sharing, information-seeking, comprehensibility have impact on COVID-19 misinformation acceptance and sharing it in the UAE culture, with gender as a moderating factor. An online survey (google.com) was used, with a sample of 200 university students, and analyzed using PLS-SEM software to determine the effects of constructed factors. The findings indicated that entertainment, information-sharing, and information-seeking factors have impact on sharing COVID-19 misinformation, while comprehensibility has impact on acceptance of misinformation. Interestingly, gender was found to have no impact on all the constructed factors, suggesting that other moderating factors (e.g., age) need to be considered in future research. Generally, online users need to learn how to verify online information that they receive/share on other social media, especially regarding health concern. [Abstract copyright: © 2023 The Authors.

A distributed architecture of parallel buck-boost converters and cascaded control of DC microgrids-real time implementation

To enhance the stability and reliability of the system, the converters’ parallel operation can be cascaded to address the constraints posed by the substantial integration of renewable resources. Buck-boost DC-DC converters are often controlled via a cascaded control approach to allow parallel operation. The converter’s output current and its voltage will be controlled by nested loop control. This study proposes adaptive droop control parameters that are updated and verified online using the principal current sharing loops to minimize the fluctuation in load current sharing. When the converters in the microgrid are paralleled, load sharing will be accomplished using the droop control approach in addition to nested proportional-integral-based voltage and current control loops. To restore the correct voltage across the DC microgrid, an outer addition voltage secondary loop will be used, rectifying any voltage disparities caused by the droop management strategy. Several common load resistances and input voltage variations are used to test the suggested method. Using a linearized model, this work assesses the stability and performance of the proposed method. It then confirms the findings with an adequate model created in MATLAB/SIMULINK, Real-Time Simulation Fundamentals, and hardware-based experiments