Technical University of Gabrovo

www.tu-gabrovo.bg
Gabrovo, Bulgaria

The Technical University of Gabrovo is a state university in Gabrovo, Bulgaria, founded in 1964. Wikipedia.


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Grant
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: GC.SST.2012.1-2. | Award Amount: 2.40M | Year: 2012

FastInCharge will last 36 months and be lead by a consortium of 9 partners (France, Spain, Greece, Bulgaria, Italia and Slovakia): 1 SME specialised in charging infrastructure for electric vehicles (DBT), 1 industrial group of automotive engineering (BATZ), 3 research organisations, specialists of contactless power, automotive engineering and energy management systems (Tecnalia, TU Gabrovo, NTU Athens), 1 end-user (Douai), 1 cluster (ACWS) , 1 SME in innovation management (EQY) and 1 OEM (CRF). The overall objective of FastInCharge is to foster the democratisation of electric vehicles in the urban environment by developing an easier and more comfortable charging solution which will enable to ease the EV use by the large public and facilitate their implementation in the urban grid. FastInCharges intention is to develop a cost-effective modular infrastructure offering a global solution for EV charging. Its success will boost research in the direction of dynamic charging solutions. The concept of FastInCharge is to create a highly performing inductive solution which will enable a 40 kW power transfer to the vehicles in two charging operational situations: one stationary and one on-route. The inductive technology developed will be integrated into: three different electric cars of different types (secondary charging block) and four charging stations, one stationary and three on-route (primary charging block). The full functional chain will be carefully scrutinised in order to ensure an optimal, safe and sustainable solution: battery charging, EV performance and safety, EV range, communication EV/Station, connection station to the grid, grid management and energy supply, intelligent coordinated systems. The programme consists in seven work packages: 1) Specifications, 2) Development of fast inductive charging infrastructure, 3) Development of integration solutions; 4) Prototyping and testing; 5) Demonstration, 6) Dissemination and Exploitation, 7) Management.


Stamova I.M.,Bourgas Free University | Ilarionov R.,Technical University of Gabrovo
Computers and Mathematics with Applications | Year: 2010

In this paper, the problem of global exponential stability for cellular neural networks (CNNs) with time-varying delays and fixed moments of impulsive effect is studied. A new sufficient condition has been presented ensuring the global exponential stability of the equilibrium points by using piecewise continuous Lyapunov functions and the Razumikhin technique combined with Young's inequality. The results established here extend those given previously in the literature. Compared with the method of Lyapunov functionals as in most previous studies, our method is simpler and more effective for stability analysis. © 2010 Elsevier Ltd. All rights reserved.


Ivanov R.,Technical University of Gabrovo
Journal of Network and Computer Applications | Year: 2012

Outdoor navigation of visually impaired people most often is based on data from the GPS maps and Geographic Information Systems (GIS). Such systems cannot be used for navigation in the regions where there are not any GPS maps or the maps are not sufficiently precise and detailed. This article describes an algorithm for real-time GPS track simplification. The test results show that the proposed algorithm (RSTS) has efficiency similar to the Douglas-Peucker algorithm, which is regarded as the best for track simplification. The reduction of the number of points in different transportation modes, while keeping the shape of the route, is over 90%. The size of the file describing the track is reduced more than 30 times. The algorithm finds the critical points of the route. This allows for navigation along the track so conversion of track to route is not needed. The algorithm is part of a low cost and widely accessible Java 2 Mobile Edition (J2ME) application for navigation of visually impaired. © 2012 Elsevier Ltd.


Ivanov R.,Technical University of Gabrovo
ACM International Conference Proceeding Series | Year: 2010

One of the most important limitations for people with visual impairment is the inability of unassisted navigation and orientation in unfamiliar buildings. An low-cost indoor navigation system, which is based on mobile terminals, supporting technology Near Field Communication (NFC), and Java program access to Radio Frequency Identification (RFID) tags, is developed. The proposed navigation system enables users to imagine the map of the rooms (dimensions, relative position of points of interest). This information is stored in RFID tags in WAP Binary eXtensible Markup Language (WBXML) format. The system allows leaving audio messages that are recorded in RFID tags in Adaptive Multi Rate (AMR) format. Voice enabled navigation, that is familiar to users with visual disabilities, is used. Copyright. © 2010 ACM.


Duncheva G.V.,Technical University of Gabrovo | Maximov J.T.,Maksimov Konsult AD
Engineering Failure Analysis | Year: 2013

The object of this paper is bolted joint railroads as the accent is put on the material behaviour around the bolted holes. The fatigue failure around rail-end-bolt holes is particularly dangerous, since it leads to derailment of trains and consequently, to inevitable accidents. Moreover, the cracking at rail-ends, which starts from bolt hole surface, causes premature rails replacement. It is well-known that the presence of residual compressive hoop stresses around the bolted holes closes the existing first mode cracks and impedes the formation of new ones and thereby extends the fatigue life of the holed components. In this article a new approach to enhancement of fatigue life of rail-end-bolt holes has been developed on the basis of a novel method and tool for cold expansion (CE) of holes, patented by the authors. The major advantage of the method is in imparting around the holes of beneficial residual compressive hoop stresses which are symmetric toward the middle longitudinal plane of the rail and thus the axial stress gradient is minimum. The developed approach consists in setting and solving a multi-objective optimization task of the CE of the rail-end-bolt holes. Because of the specificity of the studied problem, the optimal solution has been found by finite element (FE) simulations. For that purpose generalized FE model of the object has been developed. Through this model the critical point around the outside holes has been localized and the cycle of variation of hoop stresses has been determined taking into consideration assembly stresses. On the basis of adapting the generalized FE model of the rail joint to simulating the CE process, a comparison between the cases with and without CE of rail-end-bolt holes has been made. On this basis the optimal degree of CE and the successive hole treatment have been found. After simulating the CE process by the determined optimal degree of CE, the beneficial effect of implementing the new approach has been proved. © 2012 Elsevier Ltd.


Aleksandrova I.,Technical University of Gabrovo
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2016

The existing studies, concerning the dressing process, focus on the major influence of the dressing conditions on the grinding response variables. However, the choice of the dressing conditions is often made, based on the experience of the qualified staff or using data from reference books. The optimal dressing parameters, which are only valid for the particular methods and dressing and grinding conditions, are also used. The paper presents a methodology for optimization of the dressing parameters in cylindrical grinding. The generalized utility function has been chosen as an optimization parameter. It is a complex indicator determining the economic, dynamic and manufacturing characteristics of the grinding process. The developed methodology is implemented for the dressing of aluminium oxide grinding wheels by using experimental diamond roller dressers with different grit sizes made of medium- and high-strength synthetic diamonds type AC32 and AC80.To solve the optimization problem, a model of the generalized utility function is created which reflects the complex impact of dressing parameters. The model is built based on the results from the conducted complex study and modeling of the grinding wheel lifetime, cutting ability, production rate and cutting forces during grinding. They are closely related to the dressing conditions (dressing speed ratio, radial in-feed of the diamond roller dresser and dress-out time), the diamond roller dresser grit size/grinding wheel grit size ratio, the type of synthetic diamonds and the direction of dressing. Some dressing parameters are determined for which the generalized utility function has a maximum and which guarantee an optimum combination of the following: the lifetime and cutting ability of the abrasive wheels, the tangential cutting force magnitude and the production rate of the grinding process. The results obtained prove the possibility of control and optimization of grinding by selecting particular dressing parameters. © Chinese Mechanical Engineering Society and Springer-Verlag Berlin Heidelberg 2016.


Todorov T.D.,Technical University of Gabrovo
Computers and Mathematics with Applications | Year: 2015

The paper deals with a nonlinear second-order elliptic equation with Dirichlet boundary conditions. The nonlocal term involved in the strong problem essentially increases its complexity and the necessary total computational work. The existence and uniqueness of the weak solution is established. The nonlinear weak formulation is reduced to the minimization of a nonlinear functional. Finite element discretizations by Lagrangian finite elements are applied to obtain an approximate minimization problem. A two-point step size gradient method with an original steplength is used for finding approximate solutions of the problem under consideration. No line search is necessary in the new approach. The present method is computer implemented and tested on different triangulations. The test examples indicate that the method slightly depends on the initial guesses. © 2015 Elsevier Ltd.


Ivanov R.,Technical University of Gabrovo
Journal on Multimodal User Interfaces | Year: 2014

This article presents an Java-based mobile service that enables blind-environment interaction through voice-augmented objects. To make this possible, it is necessary to tag the object with an associated radio frequency identification and record its voice-based description. The blind users can later use the service to scan surrounding augmented objects and verbalize their identity and characteristics. We use a user centred design in order to guarantee the accessibility of the service for visually impaired and blind people. The required hardware is a near field communication-enabled mobile phone with built-in accelerometer. The client-side application does not require pushing any buttons, browsing any menus, or touching any screens to select and activate any of supported modes: registration, calibration, voice recording, physical object identification, delete voice recording(s), cloud-based file sync and share. Twelve visually impaired individuals (aged 31–84, 6 men and 6 women) have tested the service in two different scenarios: (1) a test based on comparison with a PenFriend labeling unit, and (2) a users’ experience test. The results show that selected tangible, multimodal interface (object touching, phone shaking and tilt, voice output) can be used very easily (58 %) or easily (33 %) by blind and visually impaired users who have had no previous experience with other mobile services. Most of participants from the test group agreed that the service could be useful for their daily activities. The service can be used both at home and in public buildings for voice description of objects such as food, medicines, books, clothes, cosmetics, CD/DVDs, rooms, etc. © 2014, OpenInterface Association.


Ivanov R.,Technical University of Gabrovo
ACM International Conference Proceeding Series | Year: 2015

This paper presents a novel approach for fast and easy access to the WEB services through interaction with Near Field Communication (NFC) smart posters. To make this possible, instead of the traditional single-touch-based interaction with the smart poster (touching a NFC tag and waiting for a response from the service) we use multiple tags touching from smart posters to generate one request (multitouch-based interaction). On the server side, each user's request, using semantic analysis is converted to a SQL query. To ensure the security of the communication between the clients and the service it is used multifactor authentication and temporary URIs to resources of the service whose names are obtained in a manner similar to that used to generate one-time passwords. The client-side mobile app, which allows access to the smart poster, does not require pushing any buttons, browsing any menus, or touching any screens. Copyright © 2015 ACM.


Ivanov R.,Technical University of Gabrovo
ACM International Conference Proceeding Series | Year: 2013

In this paper we present the design, development and implementation of the pervasive learning system for children. The required hardware is a Near Field Communication (NFC)-enabled mobile phone with built-in accelerometer. Trainers (teachers or parents) describe the objects from the learning environment through their voice and associate this voice-based description to a specific object by using the radio frequency identification (RFID) tags. They are able to sync their audio recordings, to share and re-associate with their own RFID tags (clone) audio recordings of other trainers through Google App Engine cloud environment. Children can later use the service to scan surrounding augmented objects and verbalize their identity and characteristics. The service allows the development of a variety of learning scenarios, such as getting started with the colors, letters and numbers, shape recognition, recognition of objects from learning environment, learning foreign languages, and many others. Interaction between children and objects from learning environment should be simple and intuitive. To meet this goal for invisible computing, we simulate human-human interaction than use well known human-computer interaction models. We use a tangible user interface (TUI) based on following interaction techniques: touch, gesture recognition, natural voice-based output. Preliminary results show that the service can be used easily by young children, thanks to its tangible interface that is simple, easy to use, useful, accessible and invisible to technology. © 2013 ACM.

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