Department Publications

The paper presents the combined application of Geographical Information Systems (GIS), the Global Positioning System (GPS), the General Packet Radio Service (GPRS) and the Internet for tracking of vehicle fleets. It is one component of an enterprise solution that is designed to manage and track a large fleet. The key features of the system are an open-source GIS platform, real-time location information update, and a web-based user interface. The system consists of GPS-based vehicle tracking devices, a communications server, a web-server, a database server, and a map server. The tracking devices mounted in the vehicles collect location information in real-time via the GPS. This information is transferred continuously through GPRS to a central database. The users are able to view the current location of each of the vehicles in the fleet via a web-based application, and thereby manage the fleet. The vehicle positions and other related information are displayed on a digital map, which is made available by a map server. It is a typical example of how the advantages of ICTs may be leveraged for the efficient and effective management of a company's resources, particularly in the face of skyrocketing fuel costs.

Sonar sensors are widely used in obstacle detection in mobile robotic applications and certain limitations of these sensors usually become the reason for failures in these applications. Therefore, a thorough analysis of the actual behavior of sonar sensors is required. This research studied Devantech SRF05 sonar sensor, which is the most common sonar sensor in practice. We have discovered its practical beam pattern in 3-dimension (3D), optimum trigger frequency, and maximum angle of detection.

The database correlation method (DCM) is a network based positioning technology which has shown superior in terms of accuracy. DCM is based on a pre-measured database of a location dependent variable such as received signal strength (RSS). Even though the technique has good potential, the practical difficulty in forming the database (fingerprints) using field measurements has become the major challenge in implementing this in large, dynamic networks. A remedy for this is to make use of propagation model predictions instead of field measurements to create the fingerprints. However, due to the considerable deviation between the predictions and the actual measurements, the positioning accuracy diminishes with this approach. In order to overcome this issue, tuning of the predictions using a small number of field measurements can be applied. The work presented in this paper proposes a technique for the correction of such deviations which would improve the performance of DCM. The proposed tuning process, Cell-wise Calibration, is based on artificial neural networks (ANN). Two different training algorithms, particle swarm optimization Algorithm (PSO) and BFGS Algorithm are applied for ANN training. The results of the trials carried out in urban, suburban and rural environments are presented. With the PSO algorithm, the level of accuracy is comparable to that obtained with a measured fingerprint database in urban and suburban environments, and is better in rural environment.

Wireless sensor networks are an emerging area of interest among embedded and wireless research groups around the globe. It is envisioned that these low power computers will become the enabling technology in pervasive computing and bring about the next paradigm shift in computing. We present a new type of MAC protocol that is applicable to a special type of mobile wireless sensor network. In this network, mobile sensor nodes will sense the environment, and buffer the measured data for later retrieval. Once within range of the base station, the mobile mote will have a considerable amount of data to upload to the base station. Such a system could be used in different applications such as analyzing migration patterns of animals (ex. elephants) or offline monitoring of vehicle fleets. We present a MAC protocol that will maximize the throughput of the said network, and thereby ensure that the maximum amount of …

In this paper we are presenting a low cost, locally developed customized monitoring and controlling system for a water purification plant. This system can facilitate monitoring and controlling of the entire plant from a single location. Apart from the major functions of monitoring and controlling through a GUI, additional functionalities such as providing remote terminals to the management via a LAN, generating reports, keeping logs in historical database are provided through the system.

Computer vision based spectroscopy is feasible due to the advent of faster cameras and computers. Here, spectroscopy means detecting elements based on the intensity patterns of laser induced breakdown spectra seen by a camera. This is conventionally done by using specific instruments-spectroscopes-which too may use CCD devices as the sensors. Using a commercial camera reduces the cost of the product, while enabling the testing of new detection algorithms. A simulation setup is helpful in this context. The computer vision based spectroscopy simulation, which we propose here, involves displaying patterns on a computer screen corresponding to a reduced standard database of spectra, observing the screen using a camera, and detecting the elements, preferably on a different computer. We show that, using markers and computing homographies, correct alignment of the scene and image planes can be …

Churn is a measure of the number of subscribers who leave or switch to another carrier's service. The frequent migration of customers is in a way a threat to mobile operators as the expense on customer acquisition is greater than retention. On the other hand, for any operator it is difficult to maintain a steady growth in the market without maintaining the existing customers. Due to profound competition, controlling churn rate is becoming a challenge to Mobile Operators and identifying reasons for Churn is an even greater challenge as it is highly dependent on the values, culture, attitudes and perception of the different segments.

Abstract œ The paper describes the design and development of an emergency warning network that can disseminate disaster early warnings in three languages, to vulnerable communities over the GSM network. The Disaster Early Warning Network (DEWN) is a last-mile solution for early warning of disasters, and consists of a server at a warning dissemination centre, the GSM network and user terminals. The user terminals are mobile phones with the DEWN application and electronic alarm devices capable of generating audible, high-volume alarms and flashlights. The user devices generate alarms in response to a warning message from an authorized entity via GSM‘s short message service (SMS) or cell broadcast (CB). The design of DEWN follows international guidelines on emergency communications, such as the ability to reach a large number of people very fast, awaken sleeping communities, and be able to acknowledge warning messages.

In a very high noise environment, conventional communication means suffer from significant degradation due to the external noise which can drown out the desired speech signal. Environments such as industrial complexes, manufacturing plants, battle fields are examples of extremely noisy environments. Mobility is also crucial requirement for communication in such environments frequently. The paper describes the design and implementation of a mobile wireless communication system which can operate in such an environment using effective noise cancellation techniques.

Organizations introduce acceptable use policies to deter employee computer misuse. Despite the controlling, monitoring and other forms of interventions employed, some employees misuse the organizational computers to carry out their personal work such as sending emails, surfing internet, chatting, playing games etc. These activities not only waste productive time of employees but also bring a risk to the organization. A questionnaire was administrated to a random sample of employees selected from large and medium scale software development organizations, which measured the work computer misuse levels and the factors that influence such behavior. The presence of guidelines provided no evidence of significant effect on the level of employee computer misuse. Not having access to Internet/email away from work and organizational settings were identified to be the most significant influences of work computer misuse.

The paper proposes an improved network-based positioning technique based on database correlation and presents the application of the proposed technique to GSM. The fingerprint database is created using field measurements and a novel and a more practical method for gathering fingerprints is introduced. The authors propose a Weighted k-Nearest Neighbor (WkNN) method for location estimation and the trial results obtained in urban and suburban environments in Sri Lanka are presented. Comparison with the Geometrical method shows that the proposed method is a competitive alternative for GSM location.

The paper describes the design and development of an emergency warning network that can disseminate disaster early warnings in three languages, to vulnerable communities over the GSM network. The Disaster Early Warning Network (DEWN) is a last-mile solution for early warning of disasters, and consists of a server at a warning dissemination centre, the GSM network and user terminals. The user terminals are mobile phones with the DEWN application and electronic alarm devices capable of generating audible, high-volume alarms and flashlights. The user devices generate alarms in response to a warning message from an authorized entity via GSM’s short message service (SMS) or cell broadcast (CB). The design of DEWN follows international guidelines on emergency communications, such as the ability to reach a large number of people very fast, awaken sleeping communities, and be able to acknowledge warning messages.

A Biologically Motivated Visuo-motor Controller for Composite Eye Movements in Fixation Tasks. IRIS IRIS Home Sfoglia Macrotipologie & tipologie Autore Titolo Riviste Serie IT Italiano Italiano English English LOGIN 1.IRIS 2.Catalogo prodotti della ricerca Università di Genova 3.04- Contributo in atti di convegno 4.04.03 - Poster A Biologically Motivated Visuo-motor Controller for Composite Eye Movements in Fixation Tasks. SABATINI, SILVIO PAOLO;METTA, GIORGIO 2008-01-01 Scheda breve Scheda completa Scheda completa (DC) SFX Query Anno 2008 Appare nelle tipologie: 04.03 - Poster File in questo prodotto: Non ci sono file associati a questo prodotto. I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione. Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11567/259533 Citazioni ???jsp.display-item.citation.pmc?…

We are pursuing a series of precise atomic structure measurements in atomic thallium and indium designed to test new ab initio theory calculations in these three-valence-electron systems [Phys. Rev. A 74, 022504 (2006); Phys. Rev. A 76, 022501 (2007)]. For thallium, independent atomic theory calculations are essential for atomic tests of symmetry violation. In one experiment, using two-color laser excitation, the hyperfine constants of the 6P 3/2 excited state of indium (I= 9/2) have been measured for the first time. We excite ground-state atoms to the 6S 1/2 state using a stabilized 410 nm diode laser system. A second laser beam at 1291 nm overlaps the blue beam in a heated indium vapor cell, driving Doppler-narrowed hyperfine transitions to the 6P 3/2 excited state. By modulating the blue laser beam and using lock-in detection, we obtain background-free, low-noise IR spectra. Current statistical precision is at …

Organizations introduce acceptable use policies to deter employee computer misuse. Despite the controlling, monitoring and other forms of interventions employed, some employees misuse the organizational computers to carry out their personal work such as sending emails, surfing internet, chatting, playing games etc. These ac-tivities not only waste productive time of employees but also bring a risk to the organization. A questionnaire was administrated to a random sample of employees selected from large and medium scale software development organizations, which measured the work computer misuse levels and the factors that influence such behavior. The presence of guidelines provided no evidence of significant effect on the level of employee computer misuse. Not having access to Internet/email away from work and organizational settings were identified to be the most significant influences of work computer misuse.

Simultaneous localization and map-building (SLAM) continues to draw considerable attention in the robotics community due to the advantages it can offer in building autonomous robots. It examines the ability of an autonomous robot starting in an unknown environment to incrementally build an environment map and simultaneously localize itself within this map. Recent advances in computer vision have contributed a whole class of solutions for the challenge of SLAM. This paper surveys contemporary progress in SLAM algorithms, especially those using computer vision as main sensing means, i.e., visual SLAM. We categorize and introduce these visual SLAM techniques with four main frameworks: Kalman filter (KF)-based, particle filter (PF)-based, expectation-maximization (EM)-based and set membership-based schemes. Important topics of SLAM involving different frameworks are also presented. This article …

We have developed a two-color, two-pathway coherent control technique to detect and measure weak optical transitions in atoms by coherently beating the transition amplitude for the weak transition with that of a much stronger transition. We demonstrate the technique in atomic cesium, exciting the transition via a strong two-photon transition and a weak controllable Stark-induced transition. We discuss the enhancement in the signal-to-noise ratio for this measurement technique over that of direct detection of the weak transition rate, and project future refinements that may further improve its sensitivity and application to the measurement of other weak atomic interactions.

We report a precise determination of the static polarizability of the state of atomic cesium, carried out jointly through experimental measurements of the dc Stark shift of the transition using Doppler-free two-photon absorption and theoretical computations based on a relativistic all-order method. We enhance the precision of the measurement by imposing phase-modulation sidebands on the laser beam and by using a pair of vapor cells, one of which serves as a reference, and measuring the absorption spectrum in each cell with a single scan of the laser frequency. The measured value for the polarizability of the state is , in very good agreement with our theoretical value of . In addition, the small difference in the Stark shift measurement for the two hyperfine states that we examine yields a variation in the polarizability due to the magnetic dipole contact interaction of …

This paper illustrates two techniques for improved estimation of the location of Mobile Stations (MS) in cellular Networks. The first approach is the statistical method in which signal properties are treated as random variables which are statistically dependent on the location of the transmitter and the receiver. Location estimation for a set of observed signal strengths at a specific location is done as an inference problem. In the second approach, Database Correlation, signal information seen by an MS is stored in the form of fingerprints. To estimate the location, difference between the measurement and the database fingerprints is calculated using a correlation algorithm. Database fingerprints with least difference are selected as the nearest fingerprints for the location to be estimated. The two techniques have been tested through extensive measurements in two environments, urban and sub urban, to verify their …

We describe a technique based upon the principles of two-pathway coherent control that allows one to amplify the magnitude of a weak atomic or molecular transition. In our initial demonstrations, we amplify a weak Stark-induced transition (the transition in atomic cesium) by coherently beating it with a stronger two-photon transition. We describe the measurements in detail, provide a quantitative discussion of the effects of beam overlap and alignment on the depth of modulation, and discuss the enhancement in the signal-to-noise ratio for this measurement technique over that of direct detection of the weak transition rate.

An active vision system has to enable the implementation of reactive visual processes in real time. Given a stereoscopic vision system, the vergence angle, together with version and tilt angles, describes uniquely the fixation point in space. We interpret vision and motor control, and in particular we focus on developing and testing of a control strategy that fits the Hering's law, by studying the cooperation of vergence and version movements. The analysis of the simulation results confirmed the advantages of the Hering's law to achieve fast system reactions. We show that real-time active vergence and depth estimation become possible when the estimated disparity is reliable and fast. In this framework, the advantage of a simple and fast phase-based technique for depth estimation that allows real-time stereo processing with sub-pixel resolution is also discussed.