The steel pipe umbrella is a widely used technology when tunnelling in weak soils in order to create pre-support ahead of the tunnel face. The design of steel pipes is frequently done through simplified analytical approaches which are easy to apply but require proper assessment of the loads acting on the pipe. To provide information on this key design aspect, the results of the comparison between a three-dimensional numerical model developed with the code FLAC 3D and an analytical model based on the approach of a beam on yielding supports is presented and discussed. The comparison refers to a shallow tunnel with an overburden of three times its diameter for two different types of weak rock masses. The obtained results provide suggestions about the load that has to be applied in the analytical model for the design phase.

Risks pertaining to construction work relate to situations in which various events may randomly change the duration and cost of the project or worsen its quality. Because of possible significant changes of random events, favorable, moderate, and difficult conditions of construction work are considered. It is the first stage of the construction risk analysis. The probabilistic parameters of construction are identified and described by using the design characteristics model of the structure and the construction technology model. The first describes the probabilistic properties of the structure execution's technology. The second describes the probabilistic properties of the works execution. Both models contain basic probabilistic data for scheduling, cost estimating, and risk assessment of the construction.

The paper present the concept of stability assessing the of solutions which are construction schedules. Rank have been obtained through the use of task scheduling rules and the application of the KASS software. The aim of the work is the choice of the equivalent solution in terms of the total time of the project. The selected solution optimization task should be characterized by the highest resistance to harmful environmental risk factors. To asses the stability of schedule simulation technique was used.

This paper presents an evaluation of the Hypoplastic Clay constitutive model for finite element analysis of deep excavations and displacements induced by excavations in the influence zone. A detailed description and formulation of the Hypoplastic Clay soil model is included. A parametric case study of a deep excavation executed in Pliocene clays is presented. FE analysis was performed using several soil models (Mohr-Coulomb, Modified Mohr-Coulomb, Drucker-Prager, Modified Cam-Clay, Hypoplastic Clay) and the results were compared to in-situ displacements measurements taken during construction. Final conclusions concerning the suitability of the Hypoplastic Clay model for deep excavation modelling in terms of accurate determination of horizontal displacements of the excavation wall, the uplift of the bottom of excavation, and, most importantly,vertical displacements of the terrain in the vicinity of the excavation are presented.

The paper is devoted to discussing consequences of the so-called Frisch-Waugh Theorem to posterior inference and Bayesian model comparison. We adopt a generalised normal linear regression framework and weakenits assumptions in order to cover non-normal, jointly elliptical samplingdistributions, autoregressive specifications, additional nuisance parameters andmulti-equation SURE or VAR models. The main result is that inference basedon the original full Bayesian model can be obtained using transformed dataand reduced parameter spaces, provided the prior density for scale or precisionparameters is appropriately modified.

Hydrological modelling uses modern computational methods to simulate local and regional water circulation systems. How does this work, and what benefits does it bring?

If the most parsimonious behavioral model between an observed behavior, Y, and some factors, X, can be defined as f(Y|X₁, X₂), then f_x1 will measure the impact in behavior of a change in factor X₁. Additionally, if f_x1x2 ≠ 0, then the impact in behavior of a change in factor X₁ is qualified, or moderated by X₂. If this is the case, X₂ is said to be a moderating variable and f_x1x2 is said to be the moderating effect. When Y is modeled via a logistic regression, the moderation effect will exist regardless of whether the index function of the logit specification includes a moderation term or not. Thus, including a moderation terms in the index function will help the researcher more precisely qualify the moderation effect between X₁ and X₂. The question that naturally arises is whether the researcher must include the moderation term or not. In this document, we provide the conditions in which moderation terms will naturally arise in a logistic regression and introduce some modeling guidelines. We do so by introducing a general framework that nests models with no moderation terms in three scenarios for the independent variables, commonly found in applied research.

Volatility persistence is a stylized statistical property of financial time-series data such as exchange rates and stock returns. The purpose of this letter is to investigate the relationship between volatility persistence and predictability of squared returns.

The intention of this article is to evaluate the exogenous dismissal probabilityfor a certain worker depending on her characteristics for the Polish labormarket. To model this phenomenon I considered a range of count datamodels. In the analysis the data from the Polish General Social Survey of 2008 was used. Covariates explaining the number of unemployment spells wereselected in the spirit of the human-capital theory. In the course of the studyexistence of intransferable firm-specific human capital across employers anddepreciation of the human capital acquired through learning by doing have beenempirically confirmed. The conducted analysis may be considered the first stepin the calibration of a job-search model with heterogeneous agents.

Solar radiation (Rs) is an essential input for estimating reference crop evapotranspiration, ETo. An accurate estimate of ETo is the first step involved in determining water demand of field crops. The objective of this study was to assess the ac-curacy of fifteen empirical solar radiations (Rs) models and determine its effects on ETo estimates for three sites in humid tropical environment (Abakaliki, Nsukka, and Awka). Meteorological data from the archives of NASA (from 1983 to 2005) was used to derive empirical constants (calibration) for the different models at each location while data from 2006 to 2015 was used for validation. The results showed an overall improvement when comparing measured Rs with Rs determined us-ing original constants and Rs using the new constants. After calibration, the Swartman–Ogunlade (R2 = 0.97) and Chen 2 models (RMSE = 0.665 MJ∙m–2∙day–1) performed best while Chen 1 (R2 = 0.66) and Bristow–Campbell models (RMSE = 1.58 MJ∙m–2∙day–1) performed least in estimating Rs in Abakaliki. At the Nsukka station, Swartman–Ogunlade (R2 = 0.96) and Adeala models (RMSE = 0.785 MJ∙m–2∙day–1) performed best while Hargreaves–Samani (R2 = 0.64) and Chen 1 mod-els (RMSE = 1.96 MJ∙m–2∙day–1) performed least in estimating Rs. Chen 2 (R2 = 0.98) and Swartman–Ogunlade models (RMSE = 0.43 MJ∙m–2∙day–1) performed best while Hargreaves–Samani (R2 = 0.68) and Chen 1 models (RMSE = 1.64 MJ∙m–2∙day–1) performed least in estimating Rs in Awka. For estimating ETo, Adeala (R2 =0.98) and Swartman–Ogunlade models (RMSE = 0.064 MJ∙m–2∙day–1) performed best at the Awka station and Swartman–Ogunlade (R2 = 0.98) and Chen 2 models (RMSE = 0.43 MJ∙m–2∙day–1) performed best at Abakaliki while Angstrom–Prescott–Page (R2 = 0.96) and El-Sebaii models (RMSE = 0.0908 mm∙day–1) performed best at the Nsukka station.

Fast development of computation techniques for electrolyte activities contributed recently to introduction of a few substantial programmes for thermodynamic computing of multiphase systems. The presented study comprises useful information for practical computing using selected thermodynamic models of aqueous electrolyte solutions. Those models enable quantitative description of both phase and ionic equilibria and provide values of activity coefficients. The carried out analysis of individual models involved a comparison of their practical effectiveness features along with problems encountered in evaluation of the coefficients. The authors conclude that for the Solvay soda system the exUNIQUAC model for an in-house code or the MSE model for a commercial one can be used.

This article presents the validation process of a brake FE model by means of temperature measured on a special stand using infrared technology. Unlike many other publications, the authors try to show the interaction between measurement technology and numerical modeling rather than only nice, perfectly correlated graphs. Some difficulties in choosing and using validation parameters are also pointed out and discussed. Finally, results of FE analyses are compared with measured data, followed by explanation of applied numerical technology and estimation of validation process effectiveness.

This paper adopts a fractional calculus perspective to describe a non-linear electrical inductor. First, the electrical impedance spectroscopy technique is used for measuring the impedance of the device. Second, the experimental data is approximated by means of fractional-order models. The results demonstrate that the proposed approach represents the inductor using a limited number of parameters, while highlighting its most relevant characteristics.

This research work is focused on examining the turning behavior of Incoloy 800H superalloy by varying important cutting parameters. Incoloy 800H is an Iron- Nickel-Chromium based superalloy; it can withstand high temperature (810°C), high oxidization and corrosion resistance. But, it is difficult to turn in conventional machines and hence the present work was carried out and investigated. Experiments were conducted based on the standard L27 orthogonal array using uncoated tungsten inserts. The cutting force components, namely, feed force (Fx), thrust force (Fy) and cutting force (Fz); surface roughness (Ra) and specific cutting pressure (SCPR) were measured as responses and optimized using Taguchi-Grey approach. The main effects plots and analysis of mean (ANOM) were performed to check the effect of turning parameters and their significance on responses of cutting forces in all the direction (FX, FY, FZ), the surface roughness (Ra) and specific cutting pressure (SCPR). The tool wear and machined surfaces were also investigated using white light interferometer and SEM.

In the article the author analyses the impact of the Financial Crisis, especially the Greek fiscal one, on the sCDS prices in Europe. The aim of the article is to assess the ability of the sCDS premia to price the risk of countries before and during the Greek crisis. The author analyses sCDS premia of maturity 10 years together with the so called bond-spreads, i.e. the spreadsbetween the countries’ bond indexes and the risk free rate of the region (in our case it was the yield of German bonds of corresponding maturity – 10 years).The idea was to check whether there occurred any discrepancies in the risk valuation via the two measures, as a consequence of the Greek crisis. The data is taken daily and covers the period of 2008‒2012. Based upon the results obtained in the research we conclude that the Greek crisis indeed influenced the relationships between the two measures of risk, however the degree of the influence was different in different countries. The relationships between the two measures of risk were totally broken only in the case of Greece, while in the other countries the relationships either were not distorted or had been broken already at the beginning of the financial crisis (2008/2009). The Greek problems were indeed reflected in volatilities of all analysed instruments; however triggering the credit event affected only Greek bonds dynamics.

The swap spread is defined as the difference between the fixed rate of an interest rate swap and the yield of the treasury with the same maturity. The swap spread is usually interpreted as the effective proxy of bank liquidity and the credit spread indicator. The interpretation is very similar to the LIBOR-OIS spread and in the context of Polish interbank market – WIBOR-OIS. However, WIBOR-OIS is less reliable during the crisis of confidence because of lack of interbank operation with the maturity longer than 1 month. Swap spreads base on two liquid instruments, thus they are free of this defect.

The main goal of this paper is to assess how Polish swap spreads and their conditional variance reacted to important events connected with the subprime crisis and crisis of confidence in the Polish interbank market.

Th is report provides a concise overview of the rendering and utilization of three-dimensional models in the fi eld of anatomy. Anatomical three-dimensional virtual models are widely used for educational purposes, preoperative planning, and surgical simulations because they simply allow for interactive three-dimensional navigation across the human organs or entire body. Virtual threedimensional models have been recently fabricated as accurate replicas of the anatomical structures thanks to advances in rapid prototyping technology.