Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
Publications

2014

On Predicting a Call Center's Workload: A Discretization-Based Approach

Authors
Matias, LM; Nunes, R; Ferreira, M; Moreira, JM; Gama, J;

Publication
ISMIS

Abstract
Agent scheduling in call centers is a major management problem as the optimal ratio between service quality and costs is hardly achieved. In the literature, regression and time series analysis methods have been used to address this problem by predicting the future arrival counts. In this paper, we propose to discretize these target variables into finite intervals. By reducing its domain length, the goal is to accurately mine the demand peaks as these are the main cause for abandoned calls. This was done by employing multi-class classification. This approach was tested on a real-world dataset acquired through a taxi dispatching call center. The results demonstrate that this framework can accurately reduce the number of abandoned calls, while maintaining a reasonable staff-based cost. © 2014 Springer International Publishing.

2014

Untitled

Authors
Lukovic, I; Budimac, Z; Leal, JP; Janousek, J; Rocha, A; Burdescu, DD; Dragan, D;

Publication
COMPUTER SCIENCE AND INFORMATION SYSTEMS

Abstract

2014

NUCLEAR SEISMOLOGY: THE CASE OF THE PORTO (PTO) WORLD-WIDE STANDARD SEISMOGRAPHIC NETWORK WWSSN STATION

Authors
Moura, R; Sant'Ovaia, H; Simoes, B; dos Santos, CA; Teixeira, L; Marieta Soares, JFM; Ferreira, R;

Publication
GEOCONFERENCE ON SCIENCE AND TECHNOLOGIES IN GEOLOGY, EXPLORATION AND MINING, VOL I

Abstract
The Geophysical Institute of the University of Porto (IGUP) constitutes an important pillar in the scientific and technological culture, developed over more than a century in the city of Porto. A strategic plan for its recovery has been recently developed. In terms of instruments there are currently some instruments related to seismology, meteorology and radiation, which are directly related to the measurement of variables involved in the estimation of seismic hazard and risk, meteorological hazards and radiological hazards. Thus IGUP has the potential to become a center for research in the field of Natural Hazards that in turn may contribute to studies, data and parameters for civil society and the scientific community. The Recovery that is already underway in seismic station, previously included as PTO in the world network known as Worldwide Standardized seismographic Network (WWSSN), can help achieve the implementation of a complex research in seismology and simultaneously acknowledging the geopolitical importance of this stations records. With the current work we intend to show a brief analysis of a few previously unknown seismic records, relating to Soviet nuclear explosions, as well as a few aspects of the the digital signal conversion adaptation of the previous 1960s analogue equipment.

2014

Algebra-Coalgebra Duality in Brzozowski's Minimization Algorithm

Authors
Bonchi, F; Bonsangue, MM; Hansen, HH; Panangaden, P; Rutten, JJMM; Silva, A;

Publication
ACM TRANSACTIONS ON COMPUTATIONAL LOGIC

Abstract
We give a new presentation of Brzozowski's algorithm to minimize finite automata using elementary facts from universal algebra and coalgebra and building on earlier work by Arbib and Manes on a categorical presentation of Kalman duality between reachability and observability. This leads to a simple proof of its correctness and opens the door to further generalizations. Notably, we derive algorithms to obtain minimal language equivalent automata from Moore nondeterministic and weighted automata.

2014

Preliminary clinical trial in percutaneous nephrolithotomy using a real-time navigation system for percutaneous kidney access

Authors
Rodrigues, PL; Moreira, AHJ; Rodrigues, NF; Pinho, ACM; Fonseca, JC; Lima, E; Vilaca, JL;

Publication
MEDICAL IMAGING 2014: IMAGE-GUIDED PROCEDURES, ROBOTIC INTERVENTIONS, AND MODELING

Abstract
Background: Precise needle puncture of renal calyces is a challenging and essential step for successful percutaneous nephrolithotomy. This work tests and evaluates, through a clinical trial, a real-time navigation system to plan and guide percutaneous kidney puncture. Methods: A novel system, entitled i3DPuncture, was developed to aid surgeons in establishing the desired puncture site and the best virtual puncture trajectory, by gathering and processing data from a tracked needle with optical passive markers. In order to navigate and superimpose the needle to a preoperative volume, the patient, 3D image data and tracker system were previously registered intraoperatively using seven points that were strategically chosen based on rigid bone structures and nearby kidney area. In addition, relevant anatomical structures for surgical navigation were automatically segmented using a multi-organ segmentation algorithm that clusters volumes based on statistical properties and minimum description length criterion. For each cluster, a rendering transfer function enhanced the visualization of different organs and surrounding tissues. Results: One puncture attempt was sufficient to achieve a successful kidney puncture. The puncture took 265 seconds, and 32 seconds were necessary to plan the puncture trajectory. The virtual puncture path was followed correctively until the needle tip reached the desired kidney calyceal. Conclusions: This new solution provided spatial information regarding the needle inside the body and the possibility to visualize surrounding organs. It may offer a promising and innovative solution for percutaneous punctures.

2014

Image Analysis and Recognition

Authors
Campilho, A; Kamel, M;

Publication
Lecture Notes in Computer Science

Abstract

  • 2972
  • 4387