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Open access

Žanesa Ljevo, Mladen Vukomanović and Suada Džebo

Abstract

Although the quality of a process affects the quality of the end product, there is currently an insignif­icant amount of knowledge about the quality of project management (PM) processes that directly affect the quality of the delivered product (constructed building). This study presents a proposal for modeling the impact of the quality of the PM process on the quality of the con­structed building. The quality of the PM process is rep­resented by the main quality factors and product quality indicators. It presents the results of the interviews that were conducted and study cases that were analyzed in Bosnia and Herzegovina with a variety of project partici­pants (with different managerial perspectives) in terms of the indicators of quality of the delivered product. All par­ticipants, regardless of managerial perspective, believe that the most important indicator of the quality of prod­ucts for each phase of the project is “customer satisfaction in the end phase”, the measurement of which is different for each project phase that is presented. The results of the factor analysis of the definition and the planning phases show that 11 variables, namely, the quality factors of the PM process, can be grouped into three new factors, which is described as 66.61% (77.046%) of the basic set of vari­ables.

Open access

Jiří Šimůnek, Martinus Th. van Genuchten and Radka Kodešová

Open access

Adam Szymkiewicz, Anna Gumuła-Kawęcka, Jirka Šimůnek, Bertrand Leterme, Sahila Beegum, Beata Jaworska-Szulc, Małgorzata Pruszkowska-Caceres, Wioletta Gorczewska-Langner, Rafael Angulo-Jaramillo and Diederik Jacques

Abstract

The paper presents an evaluation of the combined use of the HYDRUS and SWI2 packages for MODFLOW as a potential tool for modeling recharge in coastal aquifers subject to saltwater intrusion. The HYDRUS package for MODFLOW solves numerically the one-dimensional form of the Richards equation describing water flow in variablysaturated media. The code computes groundwater recharge to or capillary rise from the groundwater table while considering weather, vegetation, and soil hydraulic property data. The SWI2 package represents in a simplified way variable-density flow associated with saltwater intrusion in coastal aquifers. Combining these two packages within the MODFLOW framework provides a more accurate description of vadose zone processes in subsurface systems with shallow aquifers, which strongly depend upon infiltration. The two packages were applied to a two-dimensional problem of recharge of a freshwater lens in a sandy peninsula, which is a typical geomorphologic form along the Baltic and the North Sea coasts, among other places. Results highlighted the sensitivity of calculated recharge rates to the temporal resolution of weather data. Using daily values of precipitation and potential evapotranspiration produced average recharge rates more than 20% larger than those obtained with weekly or monthly averaged weather data, leading to different trends in the evolution of freshwater-saltwater interfaces. Root water uptake significantly influenced both the recharge rate and the position of the freshwater-saltwater interface. The results were less sensitive to changes in soil hydraulic parameters, which in our study were found to affect average yearly recharge rates by up to 13%.

Open access

Lory Michelle Bresciani Miristice, Dario Menichetti and Guido Gentile

Abstract

This article focuses on the simulation of transit networks, including passengers’ congestion phenomena and strategic behaviour, as a tool for planning and operation. Specifically, it describes a model of user equilibrium on large-scale transit networks considering on-board overcrowding, queuing at stops and dwelling delay, and representing in addition the effects of random events, such as the availability of seats and the waiting of vehicles, through hyperarcs. The assignment algorithm computes a strategy-based user equilibrium with implicit hyperpath enumeration by solving a fixed-point formulation, through a gradient projection method, which highly improves convergence performance. The model was implemented in .net as a dll that uses the software PTV Visum as I/O source. This article will focus on the model formulation and its capability of reproducing the target phenomena, while the results of model validation and testing will be described in a following paper.

Open access

Bernhard Pucher and Guenter Langergraber

Abstract

In this study, the simulation results of four vertical flow wetland systems using the HYDRUS Wetland Module are presented. The four wetland systems comprise three single-stage pilot scale systems and one full-scale two-stage system. The main difference between these systems is the filter media used, referred to as fine media, i.e., sand with a grain size distribution 0.063–4 mm, or coarse media, i.e., sand with grain size distributions between 1–4 mm, respectively. The water-flow simulation of each system is carried out using the single porosity van Genuchten-Mualem model. A good match between measured and simulated volumetric effluent flow rates could be achieved for all wetland systems. For reactive transport simulations, the CW2D biokinetic model was applied. First, simulations were run using the standard CW2D parameter set. For some systems, adjustments of the parameter set were needed in order to avoid unlimited bacteria growth. To better fit measured COD, NH4-N, and NO3-N effluent concentrations, adjustments of few parameters of the standard parameter set were required. The results show that for the VF wetlands with fine sand, no adjustments of the CW2D standard parameter set were needed, while for systems with coarser filter media as the main layer, the standard parameter set had to be adjusted to match simulated and measured effluent concentrations.

Open access

Elizabeth M. Pontedeiro, Paulo F. Heilbron, Jesus Perez-Guerrero, Jian Su and Martinus Th. van Genuchten

Abstract

In September 1987 an accident occurred with a cesium chloride (CsCl) teletherapy source taken from a cancer therapy institute in Goiânia, Brazil. Misuse of the abandoned source caused widespread contamination of radioactive material (about 50 TBq of 137Cs) in the town of Goiânia. Decontamination of affected areas did lead to about 3,500 m3 of solid radioactive wastes, which were disposed in two near-surface repositories built in concrete in 1995. This paper documents a safety assessment of one of the low-level radioactive waste deposits containing 137Cs over a time period of 600 years. Using HYDRUS-1D, we first obtained estimates of water infiltrating through the soil cover on top of the repository into and through the waste and its concrete liners and the underlying vadose zone towards groundwater. Calculations accounted for local precipitation and evapotranspiration rates, including root water uptake by the grass cover, as well as for the effects of concrete degradation on the hydraulic properties of the concrete liners. We next simulated long-term water fluxes and 137Cs transport from the repository towards groundwater. Simulations accounted for the effects of 137Cs sorption and radioactive decay on radionuclide transport from the waste to groundwater, thus permitting an evaluation of potential consequences to the environment and long-term exposure to the public. Consistent with previous assessments, our calculations indicate that very little if any radioactive material will reach the water table during the lifespan of the repository, also when accounting for preferential flow through the waste.

Open access

Zakaria Moutakki, Imad Mohamed Ouloul, Karim Afdel and Abdellah Amghar

Abstract

Today, Road traffic video surveillance becomes the centre of several concerns. It presents an important way for analysis of road traffic in highways. Road traffic video surveillance can help to resolve many problems which can influence road safety. This paper presents a real-time management and control system which serve to analyze road traffic using a stationary camera. The proposed system can measure the quantity and characteristics of traffic in real time based on three modules, segmentation, classification and vehicle counting. Our contribution consists of developing a feature-based counting system for vehicle detection and recognition under the conditions which present a challenge in recent systems, such as occlusions, and illumination conditions. Our method can perform vehicle detection and classification by eliminating the influence of many factors on system efficiency. The obtained results show that the system proposed in this paper provides a counting rate higher than that of some existing methods.

Open access

Valentina V. Dybskaya and Andrey B. Vinogradov

Abstract

The Russian market of logistics services suffered substantial losses during recent economic recession. Decrease in import from the EU and the USA, reduction of consumer spending within the country, increased borrowing costs led to sharp reduction in the growth rate of the investigated market value. Shortage of the modern infrastructure, fragmentation and imbalance of the Russian logistics market have contributed badly. This article focuses on identification of the promising strategic development directions for logistics service providers operating on the Russian market. On the basis of literature survey, the authors derive attractive client groups for 3PL operators, priority regions for geographical expansion as well as high-demand logistics and related services. The results of this survey could help logistics agents to define or clarify their market positioning and serve as a basis for further study of specific features in logistics outsourcing development in Russia.

Open access

Nawel Benghabrit and Mejdi Kaddour

Abstract

Cognitive Radio Networks (CRN) were introduced as a means to more efficiently reuse the licensed radio frequency spectrum. One of their salient features is the ability of unlicensed nodes to dynamically adapt their radio parameters according to their needs. This paper investigates the resource allocation problem in CRN by jointly considering power control and bandwidth for a set of secondary users (SU) transmitting simultaneously with a set of licensed users (PU), which transmissions must remain unaltered. The proposed allocation scheme is based on a Genetic Algorithm (GA) where the chromosome's genes represent the reconfigurable interface radio parameters, by defining genetic operations the GA is empowered to find a set of radio parameters that maximize the overall network capacity and under the physical interference model enforced to the transmissions of both PU’s and SU’s. The numerical results illustrate the prominent effect of adjusting jointly multiple radio parameters on the network capacity.

Open access

Klaus Berger

Abstract

Capillary barriers are an interesting alternative component for cover systems of landfills and contaminated sites. Provided they are sufficiently validated, soil hydrological models could be fast and powerful tools for the dimensioning of capillary barriers. Outflow rates measured in a 10 m long tipping trough for one material combination and two slopes from stationary periods were compared to simulation results of HYDRUS (2D/3D), Version 2.05. The measured outflow rates show a typical pattern with slope-dependent threshold values indicating the efficiency of the capillary barrier. This flow pattern could not be reproduced with HYDRUS (2D/3D) that for different input setups produced smooth patterns without thresholds. The input setup was varied for different soil hydraulic models (van Genuchten-Mualem vs. Brooks-Corey), homogeneous and heterogeneous transport domains (no scaling vs. stochastically distributed scaling factors considering the Miller-Miller similitude), different HYDRUS versions (standard vs. alternative; i.e., with material properties assigned either to finite element nodes or finite elements, respectively), and different lower boundary conditions (seepage face vs. free drainage). Differences between measured and simulated outflow patterns could be caused by the measurements, the application of the model, or by the model itself. The van Genuchten-Mualem model may not be suitable to describe the soil hydrological relationships of these particular materials. The reason for the mismatch, however, could not be identified yet.