http://hdl.handle.net/10453/148699 2026-04-27T03:06:14Z http://hdl.handle.net/10453/194800 Title: Multilayer signal-interference fourth-order high-selectivity dual-band bandpass filter with multiple transmission zeros Authors: Yang, L; Malki, M; Zhu, X; Gómez-García, R Abstract: A type of signal-interference fourth-order dual-band bandpass filter (BPF) with multiple out-of-band transmission zeros (TZs) is reported. A second-order dual-band BPF block is firstly discussed, which is composed of two microstrip-to-slotline vertical transitions that are back-to-back connected by means of an in-parallel asymmetrical microstrip-line-based closed loop. It exhibits spectrally symmetrical passbands regarding the design frequency fD and three TZs at the inter-band region. Subsequently, by using stepped-impedance-line segments at the longest path of the transversal signal-interference closed loop, its dual-band BPF counterpart with second-order spectrally asymmetrical dual passbands is presented. Next, in order to increase the filter order as well as the number of out-of-band TZs for augmented stopband attenuation, a fourth-order dual-band BPF circuit is conceived. To this aim, two Y-shaped stepped-impedance microstrip stubs are loaded at the input and output ports of the previously devised second-order frequency-symmetrical dual-band BPF block. The RF operational principles of all these dual-band BPFs are detailed through their associated transmission-line-based equivalent circuits. Moreover, for experimental-demonstration purposes, a 1.154-/2.818-GHz two-layer microstrip proof-of-concept prototype of a fourth-order sharp-rejection dual-band BPF is designed, simulated, and characterized. It features inter-band power-rejection levels higher than 28.68 dB and lower-/upper-stopband attenuation levels above 40.92 dB from DC to 4.64 GHz. 2025-01-01T00:00:00Z http://hdl.handle.net/10453/194778 Title: FEMUS-Nowcast: A Robust Deep Learning Model for Sky Image–Based Short-Term Solar Forecasting Under Adversarial Attacks Authors: Tusher, AS; Rahman, MA; Islam, MR; Bosak, S; Hossain, MJ Editors: Rai, DP Abstract: Accurate short-term solar power forecasting (nowcasting) facilitated by smart devices and cyberinfrastructure, which uses sky images and artificial intelligence (AI)–based models, is susceptible to cyberattacks. This study investigates the vulnerabilities of deep learning (DL) and artificial neural network (ANN)–based sky image–based nowcasting models to adversarial attacks such as fast gradient sign method (FGSM), projected gradient descent (PGD), and a mixed attack template, along with proposing a feature extraction–based multi-unit solar (FEMUS)-Nowcast model. Results reveal that adversarial attacks significantly degrade all models’ accuracy and lead them to an unusable state. Moreover, FGSM is found to be the most severe attack, with root mean square error (RMSE) increasing by 5–16 times and mean absolute error (MAE) increasing by 4–12 times compared to the normal scenario under maximum perturbation. As the proposed FEMUS-Nowcast outperforms models of existing literature, reducing RMSE by 48% and 25% under normal conditions, adversarial training is adapted to enhance its robustness in the presence of cyberattacks. Furthermore, adversarially trained (AT) FEMUS-Nowcast shows no RMSE or MAE trade-offs under all scenarios. Additionally, the AT FEMUS-Nowcast model demonstrates high resilience against advanced attacks, including iterative FGSM (I-FGSM) and momentum I-FGSM (MI-FGSM), confirming its reliability and robustness across diverse attack scenarios. 2025-01-01T00:00:00Z http://hdl.handle.net/10453/194762 Title: Chapter 6 Communication-centric multi-metric ISAC waveform optimization Techniques, algorithms, and indications Authors: Ni, Z; Zhang, JA Abstract: Integrated sensing and communication (ISAC) fuses the two functions into one system by sharing one transmitted signal/waveform. As a promising technique to be used in the next-generation mobile network, ISAC has the potential of making electronic devices benefit from reduced size, power consumption, cost, and improved spectrum efficiency. These benefits are not easy to achieve without the help of ISAC waveform integration. This chapter investigates ISAC waveform optimization in communication-centric systems under the constraints of multiple performance metrics. We first present radar performance metrics such as mutual information (MI), Cramér–Rao bound (CRB), and receive operating curves, and communication metrics such as spectral efficiency and signal-to-interference-plus-noise ratio (SINR). The main differences between the radar and communication metrics are disclosed. We then review related works on joint waveform optimization in ISAC systems and further study multi-metric optimizations. Specifically, we study an example of communication-centric ISAC systems by constraining the radar metrics and optimizing the SINR of communications. Simulation results are provided and validate the effectiveness of the exemplified multi-metric optimization scheme. 2025-01-01T00:00:00Z http://hdl.handle.net/10453/194700 Title: A Design of Rectifier with High-Voltage Conversion Gain in 65 nm CMOS Technology for Indoor Light and RF Energy Harvesting Authors: Hora, J; Palencia, GF; Sabarillo, R; Tugahan, J; Sun, Y; Zhu, X Abstract: In rectifier design, the key parameters are the voltage–conversion ratio and the power conversion efficiency. A new circuit design approach is presented in which a capacitor-based, cross-coupled, differential-driven topology is used to boost the voltage–conversion ratio. The scheme also integrates an auxiliary current path to raise the power conversion efficiency. To demonstrate its practicality, two three-stage rectifiers were designed and fabricated using standard 65 nm CMOS technology. The designs were tested under various conditions to assess their performance. The first rectifier targets indoor light energy harvesting applications. It achieves a peak voltage conversion ratio of 3.94 and a maximum power conversion efficiency of 58.7% when driving a 600 Ω load, while supplying over 2 mA of output current. The second rectifier is optimized for RF energy harvesting at 2.4 GHz. Experimental results indicate that it can deliver 70 µA to a 50 kΩ load, with a peak voltage conversion ratio of 5 and a power conversion efficiency of 17.5%. 2025-12-01T00:00:00Z