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The present work deals with the wet tropospheric delay estimation using the different models for navigation signals over the Indian region. Results from various mathematical models are analysed for saturation vapour pressure, partial vapour pressure, and wet delay estimation. The delay is estimated for four places in India which are spread at different geographical locations. It is observed that the Wexeler model is more suitable for saturation vapour estimation. It shows that the difference between 0.00 to 0.25 mb with reference values throughout the year. Saturation vapour pressure which is derived using the Wexeler model is further used for partial vapour pressure estimation. Four different models were used to estimate partial vapour pressure and Zyuring model is found more suitable among all. The partial vapour pressure values vary from 5 mb to 25 mb at different altitudes. The results of the Zyuring model is further used to derive wet tropospheric delay. It is found that Hopfield model provides difference of up to 4 mm in tropospheric delay, better than any other seven models results which are used for wet delay estimation. Tropospheric wet delay is observed more in daytime as compared to nighttime. From the analysis, it is found that the Hopfield model is more suitable for wet delay estimation and can be used for wet delay corrections in navigation signals for accurate position estimation. [ABSTRACT FROM AUTHOR]

The purpose of this study is Presenting the optimal impact model of contractors' claims in Design-Bid-Build (DBB) construction projects with system dynamics approach. Therefore, the purpose of the current research is fundamental at the national level, and because of this, the current situation is examined and analyzed. The current research is considered a type of system dynamics studies, in general, a mixed (quantitative-qualitative) method is used in system dynamics studies, in this research two statistical populations have been determined: theoretical experts: including university professors Azad Tehran South, whose expertise is in the field of designing and operating dynamic systems. Experienced experts: including experienced managers who work as managers of Design-Bid-Build (DBB) construction projects. And the theoretical method is used for the sample. Library and internet resources including books, articles and case studies were used to collect data related to theoretical foundations and extract primary factors and indicators. In inferential statistics, the questions were investigated using the system dynamics test and Vensim software. Based on the results obtained in the first loop, the absence or lack of materials increases the project schedule and consequently increases the project cost. In the second loop, employing skilled labor reduces the incorrect estimation by the consultant company, which leads to the reduction of the financial delays of the employer. In the third loop, the delay in providing designs increases the project schedule, which leads to an increase in the project cost. In the fourth loop, the Corona outbreak causes a decrease in the employees' performance and productivity, which results in a delay in providing designs. In the fifth loop, the change in technical specifications increases the delay in providing designs, which increases the project schedule and, consequently, increases the project cost. Accordingly, the employer benefit and employing skilled labor decreases. As a result, incorrect estimation by the consultant company and change in technical specifications will increase. [ABSTRACT FROM AUTHOR]

In this paper, we draw on recent research on so-called Fermi problems and situate the fundamental principles underlying this type of tasks and their use from a task design perspective. We use the models and modelling perspective on teaching and learning to elaborate on aspects related to the design of single-use, as well as sequences of, Fermi problems. In addition, we discuss a framework (called the Fermi problem activity template [FPAT] framework) for supporting the design and use of Fermi problems to facilitate students' learning within particular mathematics content areas and/or aimed at particular concepts or higher-order thinking skills. We also illustrate how the FPAT framework can be used to (i) facilitate interdisciplinary collaborations with other subjects such as the social sciences, but in particular with the other STEM subjects; and (ii) support teachers in adapting and implementing Fermi problems in their classrooms. [ABSTRACT FROM AUTHOR]

We sketch Friedrich Ackermann's research program following the concept of Imre Lakatos, with some historical key developments in the theory and application of aerotriangulation and image matching. The research program, with its core being statistical estimation theory, has decisively influenced photogrammetry since the 60s, is still fully alive, and a challenge for today's methods of image interpretation. We describe (1) Lakatos' concept of a scientific research program, with its negative and positive heuristics and (2) Ackermann's research program, clearly made explicit in his PhD, with its mathematical model, the ability to predict theoretical precision and reliability, the potential of analyzing rigorous and approximate method, and the role of testing. The development of aerotriangulation, later augmented by image matching techniques, is closely connected to Ackermann's successful attempts to integrate basic research and practical applications. [ABSTRACT FROM AUTHOR]

In this paper, we study a fourth order parabolic equation modeling epitaxial thin film growth. By using the potential well method and some inequality techniques, we obtain the decay estimate of weak solutions. Meanwhile, the blow-up time is estimated from above and below. The blow-up rate is also derived. [ABSTRACT FROM AUTHOR]

A decentralized supply chain network under uncertain cost is studied to obtain the optimal decisions of the enterprises in a situation in which the cost is uncertain. The supply chain network members adopt a chance-constrained approach to make decisions. The second-order cone-constrained variational inequality problem is used to construct the chance-constrained supply chain network equilibrium model. Then, the existence and uniqueness properties of the proposed equilibrium model are discussed under some mild assumptions. For the discontinuous functions in the feasible region of the model, the proposed model is converted to a second-order cone complementarity problem. The numerical results show that the uncertainty and risk attitude of retailers and manufacturers have different effects on supply chain network members. When the risk attitude is high, a small change in the risk attitude will significantly change all decisions of supply chain members. If the supply chain member is affected by the uncertainty positively, its profit will increase as its risk attitude increases. Moreover, it is appropriate to adopt a chance-constrained approach when the supply chain members can estimate the distributions of the competitor's strategies. [ABSTRACT FROM AUTHOR]

Maximal lactate steady state (MLSS) is accepted as the gold standard method to determine the upper boundary of heavy exercise domain, while critical power (CP) is one of the most practical ways to estimate the lower boundary of severe exercise domain. However, it has been recently discussed that the upper boundary of heavy-intensity exercise domain does not equal to lower boundary of severe-intensity exercise domain. Conversely, the best individual fit method (CP fit) has recently been suggested as an accurate estimation of CP. However, there has not been a comparative evaluation of CP fit versus MLSS. The aim of this study was, therefore, to focus on the comparison of CP fit with MLSS. Eleven well-trained male cyclists participated in this study. Following the determination of maximal oxygen uptake, MLSS was determined through the performance of standard 30-minute constant work rate exercises performed on separate days. Cyclists performed four constant-load exercises lasting 2–15 minutes on different days. The data were then fitted to mathematical models to obtain CP fit. Bland-Altman plot with 95% limits of agreement (LoA) was used to measure agreement between CP fit and MLSS. According to the findings, CP fit overestimated the work rate corresponding to MLSS (300 ± 38 W vs. 265 ± 39 W; P = 0.001; effect size = 3.28). Bland-Altman results showed high LoA (14 to 55.9 W) and very high bias (bias = 35 ± 10.7 W; P = 0.001; r : 0.96) between CP fit and MLSS. CP fit was not identical for MLSS. [ABSTRACT FROM AUTHOR]

The performance of a sensor-based rotor flux-oriented vector control induction machine drive is highly influenced by the estimated value of the rotor time constant/rotor resistance which varies continuously with temperature when it is driven with the variable loads. Therefore, to achieve accurate torque control, online tunning of the rotor time constant is necessary. This article proposes a novel and simple adaption technique to estimate the rotor time constant. In this proposed method, the reference model of the rotor flux vector is derived using the voltage model of the induction machine, which is independent of the rotor time constant. The current controller uses the model of the rotor flux vector that is derived using the current model of the induction machine. This current model is dependent on the rotor time constant. The error between the rotor flux vectors derived using the current model and the voltage model is minimized using the least-squares method. In this process, the rotor time constant is always tuned to its actual value. The article also presents a simple approach to estimate the parameters of induction machine like the stator resistance, the net leakage inductance, and the initial value of the rotor time constant in an offline mode at a standstill condition. To validate the proposed algorithm, two experimental prototypes are developed for two different power ratings of 3.7 and 67 kW. Experimental results from these prototypes confirm the effectiveness, reliability, and stability of the proposed algorithm both in the motoring and regenerative modes of operation. This method of the adaptation of the rotor time constant is simple and, therefore, useful for practicing engineers. [ABSTRACT FROM AUTHOR]

This study compares the conventional EGARCH(1,1) model and its extension which incorporates a realized measure of volatility, namely EGARCH-X(1,1) and REGARCH(1,1) models. The comparison is performed in terms of the estimating method performance and the model fit to the historical FTSE100 and SP500 stock indices over the daily period from January 2000 to December 2017. The models assume the Normal and Student-t distributions for the return errors and are estimated by using the GRG (Generalized Reduced Gradient) Non-Linear method in Excel's Solver and the Adaptive Random Walk Metropolis (ARWM) method which is implemented in Matlab program. The empirical study shows that the Excel's Solver's GRG Non-Linear method is able to estimate the model parameters since the estimation results are not considerably different from those obtained by ARWM method. In terms of fitting performance, the Akaike Information Criterion (AIC) indicates that the Student-t distribution seems to capture heavy tails in return distribution better than the Normal distribution. On the basis of loglikelihood ratio test and AIC, the models with realized measure (realized kernel in this study) provide a significant improvement over the EGARCH-X(1,1) model in each distribution, where the best fit model is given by the REGARCH(1,1) model with Student-t distribution. [ABSTRACT FROM AUTHOR]

• Oleic acid was successfully epoxidazed in the presence of lipase catalyst. • Experimental data were produced in a multiphase batch reactor. • Several reaction mechanisms were considered and rate equations were derived. • The proposed kinetic models are useful for molecular-level understanding and process design. The immobilized enzyme lipase acts as an efficient, selective and durable catalyst in the direct transformation of unsaturated carboxylic acids to epoxides, which are used as chemical intermediates and bio-lubricants. Experimental data obtained from the epoxidation of a model molecule, oleic acid in a laboratory-scale isothermal batch reactor were critically evaluated and mathematically modelled in the most precise way. Several rival surface reaction mechanisms were proposed and rate equations based on these mechanisms were derived. The rate equations were implemented in a multiphase model for the laboratory-scale batch reactor and the kinetic and adsorption parameters included in the rate equations were estimated with non-linear regression analysis. Based on the parameter estimation statistics and chemical knowledge, the most plausible kinetic models for the chemo-enzymatic epoxidation of oleic acid on the immobilized lipase catalyst were selected. The best kinetic models gave a good reproduction of the experimental data. The models can be used to predict the performance of enzymatic epoxidation of unsaturated fatty acids. [ABSTRACT FROM AUTHOR]