Some engineering properties of limestone: Tunnel Stra?ina case study (Croatia)

The paper presents geological and engineering geological characteristics of the Stra?ina Tunnel along the Bisko-Šestanovac section of the Zagreb-Split-Dubrovnik highway in Croatia. This paper compares the actual conditions of the rock mass during the excavation with a prediction model that preceded the excavation. From the engineering-geological viewpoint the rock mass in the tunnel was of a significantly higher quality than the prediction model. The specific geological feature of the Stra?ina Tunnel, with its right and left tunnel tube, is the passage of the right tunnel tube through a transgressive contact between Upper Cretaceous rudist limestones and Eocene foraminiferal limestones. Since this is the only tunnel in Croatia excavated through this particular transgressive contact, the geological and engineering properties of the transgression zone were up to now only assumed. Therefore, additional mineralogical, petrographical and engineering geological observations were carried out in order to determine and describe the transgression zone. The results are presented in this paper. In the left tunnel tube the contact between the mentioned litostratigraphical Units is of the fault type. This paper also briefly deals with the significance and cause of the overprofile excavation during tunneling through strongly karstified carbonate rocks. Consequently, special attention was paid to the overprofile during excavation since it can significantly affect tunneling costs.     

An examination of the mechanisms for stable foam formation in activated sludge systems

Screening pure cultures of 65 mycolic acid producing bacteria (Mycolata) isolated mainly from activated sludge with a laboratory based foaming test revealed that not all foamed under the conditions used. However, for most, the data were generally consistent with the flotation theory as an explanation for foaming. Thus a stable foam required three components, air bubbles, surfactants and hydrophobic cells. With non-hydrophobic cells, an unstable foam was generated, and in the absence of surfactants, cells formed a greasy surface scum. Addition of surfactant converted a scumming population into one forming a stable foam. The ability to generate a foam depended on a threshold cell number, which varied between individual isolates and reduced markedly in the presence of surfactant. Consequently, the concept of a universal threshold applicable to all foaming Mycolata is not supported by these data. The role of surfactants in foaming is poorly understood, but evidence is presented for the first time that surfactin synthesised by Bacillus subtilis may be important.     

Generalized charge simulation method for the calculation of the electric field in high voltage substations

This paper deals with the calculation of the electric field strength in high voltage (HV) substations comprising complex geometrical structures. Generalized charge simulation method is proposed for improving the precision of the calculation of the electric field strength. The objective of this analysis is to examine the influence of towers, HV apparatus and fences on the spatial electric field distribution. For this purpose, a three-dimensional generalized model of HV substation has been developed, including phase conductors, bypass busbars, HV apparatus, fences and towers (denoted as Full model). The obtained results of the calculation of the electric field strength are compared with the Simplified model, which only includes phase conductors connected to HV network. Verification of the proposed Full model performed by comparing the calculated and in-field measured values of the electric field strength within HV substations and in their vicinity gives very promising results.     

Adaptive content-based music retrieval system

This paper presents a tunable content-based music retrieval (CBMR) system suitable the for retrieval of music audio clips. The audio clips are represented as extracted feature vectors. The CBMR system is expert-tunable by altering the feature space. The feature space is tuned according to the expert-specified similarity criteria expressed in terms of clusters of similar audio clips. The main goal of tuning the feature space is to improve retrieval performance, since some features may have more impact on perceived similarity than others. The tuning process utilizes our genetic algorithm. The R-tree index for efficient retrieval of audio clips is based on the clustering of feature vectors. For each cluster a minimal bounding rectangle (MBR) is formed, thus providing objects for indexing. Inserting new nodes into the R-tree is efficiently performed because of the chosen Quadratic Split algorithm. Our CBMR system implements the point query and the n-nearest neighbors query with the O(logn) time complexity. Different objective functions based on cluster similarity and dissimilarity measures are used for the genetic algorithm. We have found that all of them have similar impact on the retrieval performance in terms of precision and recall. The paper includes experimental results in measuring retrieval performance, reporting significant improvement over the untuned feature space.     

Parallel programming for multimedia applications

Computing capabilities are continuing to increase with the availability of multi core and many core processors. The wide availability of multi core processors has made parallel programming possible for end user applications running on desktops, workstations, and mobile devices. While parallel hardware has become common, software that exploits parallel capabilities is just beginning to take hold. Multimedia applications, with their data parallel nature and large computing requirements will benefit significantly from parallel programming. In this paper an overview of parallel programming is presented and languages and tools for parallel programming such as OpenMP and CUDA are introduced within the scope of multimedia applications.     

An electromagnetism metaheuristic for solving the Maximum Betweenness Problem

In this paper we present an electromagnetism (EM) metaheuristic for solving NP hard Maximum Betweenness Problem (MBP). A new encoding scheme with appropriate objective functions is implemented. Specific representation of the individuals enables the EM operators to explore the searching space in a way that achieves high quality solutions. An effective 1-swap based local search procedure improved by the specific caching technique is performed on each EM point. The algorithm is tested both on real and artificial instances from the literature. Experimental results show that the proposed EM approach achieves all previously known optimal solutions, except one, and achieves the best-known solutions or outperforms other approaches on all large-scale instances, except two. Provided statistical analysis indicates that the EM approach is significantly better than other approaches.     

Setting up a competition framework for the evaluation of structure extraction from OCR-ed books

This paper describes the setup of the Book Structure Extraction competition run at ICDAR 2009. The goal of the competition was to evaluate and compare automatic techniques for deriving structure information from digitized books, which could then be used to aid navigation inside the books. More specifically, the task that participants faced was to construct hyperlinked tables of contents for a collection of 1,000 digitized books. This paper describes the setup of the competition and its challenges. It introduces and discusses the book collection used in the task, the collaborative construction of the ground truth, the evaluation measures, and the evaluation results. The paper also introduces a data set to be used freely for research evaluation purposes.     

Performance measurement of e-learning using student satisfaction analysis

The purpose of this paper is to analyze e-learning system quality through the analysis of student satisfaction and the usage of learning materials. This analysis takes into consideration both online and traditional students who are using the same e-learning system. The goal of the analysis is to identify factors which influence student satisfaction and to address heterogeneous styles and needs of both groups of students, so that future pedagogical and motivational methods in teaching and learning can be appropriately selected, developed and implemented. It was of particular interest to explore student satisfaction with quality of an e-learning system and online study approach. Reasons that may influence opinions of online and traditional students are examined and presented. The results are used to give recommendations for e-learning improvements and to propose the model with 4 groups of dimensions for performance measurement each of which best represents satisfaction of both groups of students.     

Flow profile measurement in microchannel using the optical feedback interferometry sensing technique

The need to accurately measure flow profiles in microfluidic channels is well recognised. In this work, we present a new optical feedback interferometry (OFI) flow sensor that accurately measures local velocity in fluids and enables reconstruction of a velocity profile inside a microchannel. OFI is a self-aligned interferometric technique that uses the laser as both the transmitter and the receiver thus offering high sensitivity, fast response, and a simple and compact optical design. The system described here is based on a commercial semiconductor laser and has been designed to achieve a micrometer-range spatial resolution. The sensor performance was validated by reconstructing the velocity profile inside a circular cross-section flow-channel with 320  $\upmu $ m internal diameter, with a relative error smaller than 1.8 %. The local flow velocity is directly measured, thus avoiding the need for model based profile calculation and uncertainties inherent to this approach. The system was validated by successfully extracting the flow profiles in both Newtonian and shear-thinning liquids.     

FM radio for indoor localization with spontaneous recalibration

The position of mobile users has become highly important information in pervasive computing environments. Indoor localization systems based on Wi–Fi signal strength fingerprinting techniques are widely used in office buildings with an existing Wi–Fi infrastructure. Our previous work has proposed a solution based on exploitation of a FM signal to deal with environments not covered with Wi–Fi signal or environments with only a single Wi–Fi access point. However, a general problem of indoor wireless positioning systems pertains to signal degradation due to the environmental factors affecting signal propagation. Therefore, in order to maintain a desirable level of localization accuracy, it becomes necessary to perform periodic calibrations of the system, which is either time consuming or requires dedicated equipment and expert knowledge. In this paper, we present a comparison of FM versus Wi–Fi positioning systems and a combination of both systems, exploiting their strengths for indoors positioning. We also address the problem of recalibration by introducing a novel concept of spontaneous recalibration and demonstrate it using the FM localization system. Finally, the results related to device orientation and localization accuracy are discussed.