- TITLE: INVESTIGATION OF A MUFFLER WITH MODIFIED HELMHOLTZ RESONATOR VOLUME UNDER MULTI-LOAD OPERATING MODES
- AUTHOR(S): H. Kuşçu, T. Pektaş
- ABSTRACT: Helmholtz resonators are widely applied in exhaust aftertreatment systems to improve acoustic attenuation, but their performance depends on resonator volume and engine operating conditions. This study examines the effect of enlarging the resonator volume from 30.67 L to 57.83 L on the acoustic behavior of a prototype muffler. The objective was to evaluate transmission loss at multiple load points and provide a basis for future optimization. Acoustic measurements were performed under five operating modes, defined by engine speed and torque, with a microphone placed at the outlet. Results were benchmarked against a reference muffler. The modified design achieved notable improvements in insertion loss for four out of five modes, with relative gains up to 46%. Only at the lowest load condition (Mode 1) was a decrease observed. Back pressure remained within acceptable limits, indicating no major penalty in flow performance. Findings confirm that resonator volume has a strong influence on acoustic characteristics across operating conditions. While the prototype achieved substantial improvements, variations between modes emphasize the need for designs optimized for all load points. This work provides experimental evidence on the relationship between resonator volume and acoustic performance, serving as a foundation for future research in multi-load-point optimization.
- DOI: http://doi.org/10.62853/WRTX8487
- PAGES: 25-27
- DOWNLOAD: Vol71-2025-5-25-27.pdf
- HOW TO CITE THIS ARTICLE: H. Kuşçu, T. Pektaş. Investigation of a muffler with modified helmholtz resonator volume under multi-load operating modes. Journal of the Technical university of Gabrovo. 71 (2025) 25-27.
- TITLE: DESIGN AND DEVELOPMENT OF A MULTI-PURPOSE COMPOUND PRODUCTION MACHINE WITH INTERLOCKING AND CO-ROTATING REVERSE CONICAL SCREWS
- AUTHOR(S): B. Avci, S. Uner, M. Agu, F. Dalmis, S. O. Yilmaz, I. S. Dalmis
- ABSTRACT: Polymer-based compounds such as PVC, HFFR, PE, PP, and engineering polymers are widely used in the cable industry as sheath, insulation, and filling materials due to their mechanical, electrical, and environmental advantages. However, in their processing, challenges such as mixing homogeneity and production efficiency remain significant limitations in conventional systems. Inadequate mixing or uneven dispersion of additives not only reduces production efficiency but also directly affects the mechanical properties of the final product such as tensile strength, elongation value and flexibility. In this study, a multi-purpose compound production machine equipped with intermeshing and co-rotating counter-conical screws was designed, manufactured, and tested. The system consists of six main components: ribbon mixer, feeding unit, twin conical screws, transfer screw, granule cutting and cooling unit, and a PLC-based main control panel (HMI). The homogeneity and desired dispersion of the compound were confirmed by microscopic examinations, SEM analysis, and mapping analysis. Mechanical tests demonstrated that the compound had a tensile strength of 14.72 N/mm² and an elongation value of 173%, along with hardness, density, and moisture measurements, all meeting industrial standards. The developed machine provides significant advantages over conventional systems in terms of mixture homogeneity and production efficiency.
- DOI: http://doi.org/10.62853/BADN5930
- PAGES: 28-33
- DOWNLOAD: Vol71-2025-6-28-33.pdf
- HOW TO CITE THIS ARTICLE: B. Avci, S. Uner, M. Agu, F. Dalmis, S. O. Yilmaz, I. S. Dalmis. Design and development of a multi-purpose compound production machine with interlocking and co-rotating reverse conical screws. Journal of the Technical university of Gabrovo. 71 (2025) 28-33.
- TITLE: INSPECTION OF AIRCRAFTS’ WHEELS, THEIR MATERIALS AND APPLICATIONS – A REVIEW
- AUTHOR(S): Ş. Karakaya, T. Altinbalik
- ABSTRACT: As of today, when people discuss regarding aviation, it is seen that it has become an important factor that affects the lives of millions of people all around the world. Not only as civil aviation, but also as an important factor for determining borders in wars. When we consider civil aviation, airplanes shorten distances, allowing us to re-evaluate the terms of time and distance, making modern humans access to almost every land mass in the world. It is generally accepted that civil aviation began with the first powered flight by the Wright Brothers in North Carolina in 1903. However, it is a fact accepted by almost everyone that mankind's love of flying dates back much further. Hezarfen Ahmet Çelebi, who lived in the Ottoman Empire between 1609 and 1640, is the best example of this. According to the story in the Seyahatname (travel book) of Evliya Çelebi, one of the Ottoman travelers, Hezarfen Ahmed Çelebi, jumped from the Galata Tower with a southwestern wind in 1632, wearing a device resembling bird wings, glided 3,358 meters across the Bosphorus and landed in Üsküdar. It is a well example for mankind’s passion for flying. However, if we consider about flight with engine how The Wright Brothers did, civil aviation became a rapidly developing sector after this flight onwards and air transportation became an important sector around the world with the start of commercial flights. Rapid development and widespread use of aircrafts have also revealed the importance of aircraft components. One of the most important of these components is the landing gear and the aircraft wheels, which are part of this landing gear. Aircraft wheels, which play an active role in the take-off and landing moments of aircraft, are the most intense area which exposed to impact and are one of the components that absorb these impacts.
- DOI: http://doi.org/10.62853/YHQM7087
- PAGES: 34-38
- DOWNLOAD: Vol71-2025-7-34-38.pdf
- HOW TO CITE THIS ARTICLE: Ş. Karakaya, T. Altinbalik. Inspection of aircrafts’ wheels, their materials and applications – a review. Journal of the Technical university of Gabrovo. 71 (2025) 34-38.
- TITLE: FINITE ELEMENT ANALYSIS OF WIRE DRAWING PROCESS USING DEFORM-3D SOFTWARE
- AUTHOR(S): Ö. Ayer.
- ABSTRACT: This study presents a finite element analysis of the wire drawing process using the DEFORM-3D software. The objective is to model and evaluate the influence of drawing speed on stress and temperature distributions during cold forming. In the simulations, the first drawing pass - reducing the wire diameter from Ø5.50 mm to Ø4.74 mm - was modeled. The material was defined as AISI 1008 steel, and the die was assumed rigid under room temperature conditions (20°C). Three different drawing speeds (5 m/s, 7 m/s, and 10 m/s) were applied to analyze their effect on the process. The results indicate that both effective stress and drawing force increase with higher drawing speeds, reaching up to approximately 530 MPa. Likewise, temperature rises due to friction and plastic deformation, attaining about 140°C near the die exit zone. The study demonstrates that FEM-based numerical simulation is an effective tool for predicting process behavior, optimizing die design, and improving product quality in wire drawing operations.
- DOI: http://doi.org/10.62853/HWIT6420
- PAGES: 39-42
- DOWNLOAD: Vol71-2025-8-39-42.pdf
- HOW TO CITE THIS ARTICLE: Ö. Ayer. Finite element analysis of wire drawing process using deform-3d software. Journal of the Technical university of Gabrovo. 71 (2025) 39-42.
- TITLE: EVALUATION OF THE GRADIENT BOOSTING ALGORITHM BASED ON TRAIN/TEST RATIOS IN SOLAR ENERGY POWER GENERATION FORECASTING
- AUTHOR(S): D. Akal, T. Tez, İ. Umut.
- ABSTRACT: Accurate forecasting of solar energy generation is of critical importance for energy planning, resource management, and sustainability efforts. This study investigates the performance of the Gradient Boosting algorithm in predicting solar power output. The analysis utilizes the Solar Energy Power Generation Dataset obtained from the Kaggle platform. The dataset comprises hourly meteorological variables such as temperature, humidity, pressure, precipitation, various cloud cover types, shortwave radiation, wind speed and direction, solar angles, as well as the corresponding power generation values. During the preprocessing phase, the data were imported into the Orange open-source data analysis software, where variable names were standardized and transformed into a format suitable for modeling. Gradient Boosting was selected as the predictive algorithm, and its performance was evaluated under various train/test split ratios (50%, 60%, 66.6%, 70%, 75%, 80%, 90%, and 95%). Several essential performance metrics including the coefficient of determination (R²), root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) were employed to assess the model's performance. The highest R² value (0.790) and the lowest error rates were achieved with a 90% training ratio (RMSE=428.959, MAE=289.195). However, a slight performance decline observed at the 95% training ratio suggests a potential risk of overfitting. Overall, the findings demonstrate that Gradient Boosting is a reliable and effective method for forecasting solar energy generation, with optimal results obtained at the 90% training level. Future studies may achieve higher accuracy and generalization capacity through the integration of alternative boosting algorithms and hyperparameter optimization techniques.
- DOI: http://doi.org/10.62853/HHZK1143
- PAGES: 43-46
- DOWNLOAD: Vol71-2025-9-43-46.pdf
- HOW TO CITE THIS ARTICLE: D. Akal, T. Tez, İ. Umut. Evaluation of the gradient boosting algorithm based on train/test ratios in solar energy power generation forecasting. Journal of the Technical university of Gabrovo. 71 (2025) 43-46.
