- TITLE: CONSTRUCTING A ROBOT BASE FRAME CAPABLE OF BALANCING ITS CENTER OF GRAVITY
- AUTHOR(S): D. A. Viet
- ABSTRACT: This study presents the design and experimental validation of a compact robot base frame capable of actively balancing its center of gravity through linear mass redistribution. The system employs a lead-screw-driven sliding counterweight actuated by a NEMA 17 stepper motor and regulated by a real-time proportional controller with hysteresis-based state logic. An analytical moment-balance model establishes the relationship between counterweight mass and maximum compensable load, demonstrating that the balancing capacity is approximately 69% of the counterweight mass under the given geometric constraints. Controller tuning shows that a pure proportional gain Kp=40 achieves a settling time of approximately 16 s with zero overshoot. Experimental multi-load disturbance tests confirm stable bidirectional compensation, accurate load detection within 100 ms, and effective suppression of hunting behavior through a ±100 g deadzone and a 20 g hysteresis band. The results demonstrate that a mechanically simple, single-degree-of-freedom translational mechanism can provide reliable and repeatable mass-based stabilization for compact robotic platforms.
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- DOWNLOAD: Vol72-2026.pdf
- HOW TO CITE THIS ARTICLE: D. A. Viet, CONSTRUCTING A ROBOT BASE FRAME CAPABLE OF BALANCING ITS CENTER OF GRAVITY. Journal of the Technical University of Gabrovo. 72 (2026).
- TITLE: USE OF IMAGE ANALYSIS IN THICKNESS PREDICTION OF THERMOFORMED PACKAGING
- AUTHOR(S): O. Eksi, K. Feratoglu, S. Karabeyoglu
- ABSTRACT: In this study, Image Analysis was used as a verification tool in thickness prediction of thermoformed packages. First, the thickness distribution of thermoformed packages in three different colours was obtained experimentally. Then, thickness variation was estimated using the light transmittance of thermoformed packages. Particularly, the light-transmitting side walls of the packaging were taken into consideration, and the thickness of the side walls was predicted. ImageJ, a Java-based, open-source Image Processing software, was used to generate thickness predictions. Predicted and obtained thickness values were compared to each other. Thickness values predicted by ImageJ, showed good agreement with the experimental results.
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- PAGES:
- DOWNLOAD: Vol72-2026.pdf
- HOW TO CITE THIS ARTICLE: O. Eksi, K. Feratoglu, S. Karabeyoglu, USE OF IMAGE ANALYSIS IN THICKNESS PREDICTION OF THERMOFORMED PACKAGING. Journal of the Technical University of Gabrovo. 72 (2026).
- TITLE: ANALYSIS OF THE EXPERIENCE FOR CLIMATE MODERNIZATION OF ENGINEERING SYSTEMS IN BUILDINGS
- AUTHOR(S): V. Aftaniuk, D. Sengl, E. Parada
- ABSTRACT: In this paper, an analysis of solutions for adapting existing buildings to changing operating conditions, climate and technological requirements is fulfilled. Dynamic modernization allows the sustainable operation of buildings, taking into account modern standards for engineering systems. The projects under consideration use flexible engineering solutions that allow according to response changes in load, and prospects for ensuring the stability of automation while taking into account user comfort. The main objective in the considered examples of building modernization is to study the experience of work on the modernization of engineering systems of buildings, on the basis of which approximate economic and environmental assessments were obtained that correspond to similar projects.
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- PAGES:
- DOWNLOAD: Vol72-2026.pdf
- HOW TO CITE THIS ARTICLE: V. Aftaniuk, D. Sengl, E. Parada, ANALYSIS OF THE EXPERIENCE FOR CLIMATE MODERNIZATION OF ENGINEERING SYSTEMS IN BUILDINGS. Journal of the Technical University of Gabrovo. 72 (2026).
- TITLE: HEAT TRANSFER ANALYSIS OF FULLY DEVELOPED TURBULENT NON-NEWTONIAN NANO AND HYBRID NANOFLUID FLOW IN A HORIZONTAL PIPE UNDER CONSTANT HEAT FLUX
- AUTHOR(S): D. Ozgur
- ABSTRACT: This study investigates the thermal and flow characteristics of fully developed turbulent non-Newtonian (power-law type) nano and hybrid nanofluids flowing through a horizontal pipe under constant heat flux. Carboxymethylcellulose (CMC) solution is used as the base fluid, while Al₂O₃, CuO and hybrid (Al₂O₃+CuO) nanoparticles are employed as additives. The governing equations are non-dimensionalized and solved under steady-state and axisymmetric assumptions. Nusselt number, friction factor, and thermal performance ratio (TPR) are analyzed. Results show that hybrid nanofluids provide approximately %15–20 higher heat transfer enhancement compared to mono nanofluids, while the increase in friction factor remains moderate. The optimum particle volume fraction is found to be around φ≈%2.5. This study demonstrates that hybrid nanofluids in non-Newtonian matrices are efficient alternatives for improving convective heat transfer in turbulent flow systems.
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- PAGES:
- DOWNLOAD: Vol72-2026.pdf
- HOW TO CITE THIS ARTICLE: D. Ozgur, HEAT TRANSFER ANALYSIS OF FULLY DEVELOPED TURBULENT NON-NEWTONIAN NANO AND HYBRID NANOFLUID FLOW IN A HORIZONTAL PIPE UNDER CONSTANT HEAT FLUX. Journal of the Technical University of Gabrovo. 72 (2026).
- TITLE: OPTIMIZATION OF SURFACE ROUGHNESS IN MILLING ALUMINUM 7075-T6 USING THE TAGUCHI METHOD
- AUTHOR(S): F. B. Genc, I. S. Dalmis
- ABSTRACT: Machining processes, particularly milling, play a critical role in achieving high-precision components in subtractive manufacturing. Surface roughness is a key indicator of surface quality, influencing mechanical performance, fatigue life, and assembly fit in industrial applications. This study utilizes the Taguchi method to optimize machining parameters - cutting speed, feed rate, and depth of cut - for minimizing surface roughness (Ra) during the milling of Aluminum 7075-T6 alloy, a material extensively employed in aerospace, automotive, and military sectors due to its high strength-to-weight ratio. Experimental trials were conducted using an L9 orthogonal array, with results analyzed through signal-to-noise (S/N) ratios, analysis of variance (ANOVA), and regression modeling. The findings reveal that feed rate exerts the most significant influence on Ra (50.75% contribution), followed by cutting speed (28.34%) and depth of cut (12.75%). Optimal parameters identified are a cutting speed of 430 m/min, feed rate of 500 mm/min, and depth of cut of 0.3 mm, yielding a predicted Ra of 0.08967 μm. These optimizations enhance manufacturing efficiency and component durability, providing practical insights for precision engineering.
- DOI:
- PAGES:
- DOWNLOAD: Vol72-2026.pdf
- HOW TO CITE THIS ARTICLE: F. B. Genc, I. S. Dalmis, OPTIMIZATION OF SURFACE ROUGHNESS IN MILLING ALUMINUM 7075-T6 USING THE TAGUCHI METHOD. Journal of the Technical University of Gabrovo. 72 (2026).
