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Gabrovo, Bulgaria

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

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. Source

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. Source

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. Source

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. Source

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. Source

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