In this study, four different directional couplers with increasing structural complexity (Coupler I, II, III, and IV) were designed and analyzed using the Ansys full-wave simulator. The designs, implemented on an FR-4 substrate, were derived from a fundamental configuration by adding and removing geometric features. A comparative analysis of the simulation results indicates that Coupler II exhibits superior performance for wideband applications, offering a return loss better than -15 dB, a flat coupling factor, and deep isolation below -40 dB over the wide frequency range of 1.5 GHz to 4.5 GHz. The focus of the study is a parametric analysis conducted on Coupler IV, which investigates the effect of the geometric parameter 'p'. This analysis revealed that the 'p' parameter is a powerful tool for precisely tuning the coupler's operating bandwidth, impedance matching, and filtering characteristics. It was observed that by increasing the 'p' value, the upper cut-off frequency of the operating band can be lowered, while simultaneously creating an adjustable notch (rejection band) in the transmission response. These results demonstrate that tuning the geometric parameter provides critical flexibility for optimizing directional couplers for specific application requirements, such as wideband, narrowband, or integrated filtering.
Öykü Berfin Mercan, Mansur Alp Toçoğlu, Nezihe Turhan Turan, Aytuğ Onan
Biomedical texts typically contain a high level of technical terminology and complex sentence structures, which limits their comprehensibility for readers without domain expertise. Text simplification, a natural language processing problem, aims to transform complex texts into a more readable and accessible form while preserving their original semantic content. Especially in biomedical texts, simplification can play an essential role in making scientific information understandable to patients and the general public. In this context, this study investigates the text simplification performance of pre-trained general-purpose and domain-specific language models (PLMs) for biomedical texts. The experiments utilize the Cochrane-Simplification dataset, which comprises technical abstracts from systematic reviews and their corresponding plain language summaries. General-purpose models and summarization tuned variants (BART-Large, BART-Large-CNN, BART-Large-XSum, PEGASUS-Large, PEGASUS-XSum, T5 and FLAN-T5) are compared alongside domain-specific models (BioBARTv2-Large, SciFive, Clinical-T5) under comparable fine-tuning settings. The models were compared using ROUGE, BLEU, BERTScore and SARI metrics to measure textual similarity and semantic coherence. The results indicate that BART based models achieve superior performance in the medical text simplification task.
Video streaming performance is strongly influenced by transport-layer behavior under bandwidth constraints. This paper provides a protocol-oriented comparative analysis of four video transmission approaches: DASH streaming, TCP-based transmission, UDP-based transmission, and Big Packet Protocol (BPP) transmission with trimming support. Using a controlled experimental framework, we evaluate delivery continuity, quality variability, and low-latency playback behavior through throughput/bitrate dynamics, frame/layer reception patterns, and total pause duration. The results show that DASH achieves the most consistent playback continuity in moderate and time-varying conditions through segment-level adaptation, while BPP approaches DASH-level continuity in dynamic scenarios by enabling graceful degradation via trimming. UDP is highly sensitive to bandwidth limitation and loss, leading to unstable reception and persistent interruptions. TCP preserves constant decoded quality without switching due to retransmissions, but incurs the largest stall durations, making it less suitable for low-latency streaming targets. Overall, the findings highlight a fundamental trade-off between continuity and reliability and motivate practical guidance for selecting transmission mechanisms under both fixed and dynamic bottleneck conditions.
