An assessment of models for wastewater sludge characterization

One of the important aspects of the models used for wastewater sludge transport is the determination of energy loss when pumped on long distances. In the literature, two types of non‐Newtonian fluids, the Bingham plastic and the pseudoplastic fluids, have been assumed and received special attention. Based on these two classifications, formulae are derived for the design of pipelines. The purpose of this investigation is to evaluate the existing models for characterising the non Newtonian properties of wastewater sludge and to investigate the effect due to the testing scale of the experimental facilities. As a result, the statistical analysis of the examined data provide useful information for the adequacy of these models.     

Education for Sustainability: Experiences from Greece

Increasing awareness of sustainability has affected civil engineering education, making it more complex and demonstrating the connections to economic, social, and technological problems. Environmental consciousness in the Organization for Economic Cooperation and Development countries is growing, but in Greece the subject still tends to remain a marginalized and compartmentalized corner of educational systems. Environmental education means more than transmitting knowledge about the environment; it is also about educating for sustainable development. One of the main issues involved is changing people’s attitudes, values, behavior, and consumption patterns. University education in Greece aims to educate engineers so that besides acquiring theoretical knowledge they also learn to show personal responsibility and are motivated to act sustainably. Educating for sustainable development also entails the development of critical capacities and the necessary skills to be able to identify and formulate problems. This paper outlines the way in which a multidisciplinary approach to teaching sustainability has been embodied in the Civil Engineering Department at the University of Thessaly, Greece. More specifically, it describes a course to develop a comprehensive information technology-based learning resource comprising a set of multidisciplinary case studies and support material in order to aid engineering students in understanding the sustainability concepts and how solutions can be developed.     

A compromise programming model for site selection of borrow pits

Road fill construction requires soil for filling low areas; this soil is obtained from temporary mineral workings known as ‘borrow pits’ (BP). Between a number of possible BPs, the appropriate site should be selected based upon conflicting econo‐technical and environmental criteria aiming at achieving optimal BP performance while minimizing the adverse impacts to human and natural resources. For solving this problem a model for BP selection has been developed by this research using compromise programming (CP). The model incorporates a hierarchical structure integrating criteria and sub‐criteria whose relative importance is set by the decision makers. Possible alternative BP sites are subsequently assessed on all these sub‐criteria. Based upon this analysis, the model determines the distance of each of the possible alternatives from the utopia (ideal) point; the option with the minimum distance is considered the best compromise. The relevant concepts are exemplified through the presentation of a case study concerning the BP site selection for an Egnatia Motorway section in northwest Greece. The main conclusion that can be drawn from this work is that the CP approach is appropriate and valid for BP selection and, furthermore, it may also be used for other multiple objective construction‐related site selection problems.     

Comparative Performance Analysis of the MWIR and LWIR Focal Plane Array Starring Imaging Infrared Systems

This paper review the fundamental physics of IR radiation and describes the predictive techniques and the methods of signature management for the specific exploitation of Imaging Infrared Surveillance Systems for shore based or ship borne surface to surface and low altitude air to surface scenarios, which are the most widely used. The parameters affecting the performance of the FLIR systems, such as target and background characteristics, atmospheric transmission and detector features are individually analyzed, in order to reach to FLIR performance assessment using either MWIR or LWIR bands. For this purpose the special scenario of maritime applications has been paying special consideration.     

Sustainability Indices of Thermal Electrical Power Production in Greece

The present paper provides some evidence regarding the thermal electrical power production sector of Greece evaluating performance indicators as signposts of sustainability. The methodology used was data envelopment analysis applied for each one of the yearly activities of thermal electrical power production sector. In the present study two evaluations are carried out. The first one takes into account only corporate data (i.e., inputs and outputs of production process), though in the second one environmental impact data (i.e., NOx and SO2 emissions) are also included. According to the results, in the late 1980s the performance of Public Power Corporation, the exclusive electricity producer, was efficient compared to the previous yearly activities considered here.