Search Results (2,209)

This research focuses on the design and simulation of a V-band single-chip transmit-and-receive front-end integrating an LNA, PA and switching functions for ISL terminals. Two technologies are compared: a 60 nm GaN/Si HEMT from MESC and a 100 nm GaAs HEMT from UMS. In Tx mode, the proposed design targets a saturated output power of at least 20 dBm and a power-added efficiency of no less than 5%. In Rx mode, the goal is 4 dB noise figure. In both cases, the small signal gain must exceed 20 dB across the 59–71 GHz band. Full article

DC bias is a primary cause of anomalous vibration and noise in power transformers. This study investigates the magnetostriction characteristics of grain-oriented silicon steel sheets under simultaneous AC excitation and DC bias. A novel prediction method is proposed, which integrates multi-scale mutual information features with frequency-domain features, and employs a long short-term memory (LSTM) network for DC bias identification. The experimental platform with six voltage levels and seven bias ratios was set up to collect strain signals under various operating conditions. The results indicate that DC bias alters the magnetostriction spectrum by modulating the nonlinear response. Specifically, the amplitude of the 100 Hz harmonic decreases monotonically as bias increases, whereas the high-frequency harmonics are noticeably amplified, leading to greater waveform asymmetry and harmonic distortion. The proposed prediction model achieves a root-mean-square error (RMSE) of 0.0336 and a coefficient of determination (R²) of 0.8810 under stratified 5-fold cross-validation, offering theoretical support and experimental evidence for DC bias monitoring and transformer condition assessment. Full article

Visible light communication (VLC) employs light-emitting diodes (LEDs) for simultaneous illumination and wireless data transmission, offering advantages such as unlicensed spectrum, immunity to electromagnetic interference, and intrinsic security. Conventional PAM-VLC transmitters generally rely on a single high-power LED driven by analog front-end components, such as digital-to-analog converters and power amplifiers, which increase hardware complexity, power consumption, and thermal burden. To address these limitations, this paper proposes an energy-efficient spatial-combining VLC transmitter in which multiple LEDs are directly driven by FPGA GPIO ports, without using DACs or power amplifiers. Multilevel PAM is digitally realized by controlling the number of activated LEDs, and the emitted optical signals are spatially combined through an optical lens. Experimental results demonstrate reliable 1 m free-space transmission. At a bit-error rate (BER) of 3.8 × 10⁻³, the proposed scheme achieves SNR gains of 0.75 dB for PAM-4 and 0.8 dB for PAM-8 over the conventional pulse amplitude modulation (PAM)-VLC architecture. Moreover, the proposed transmitter reduces power consumption by 38.7%. These results confirm that digitally driven multi-LED spatial combining is a promising solution for low-cost and energy-efficient VLC systems. Full article

This study investigates the communicative power of editorial cartoons in Ghana’s public discourse, focusing on how they inform, critique, and influence sociopolitical narratives. Drawing on a dataset of cartoons by Tilapia—one of the country’s leading cartoonists—published between May 2024 and May 2025, the paper explores how cartoons address themes such as economic hardship, youth addiction, cultural values, environmental degradation, and political hypocrisy. The central question guiding this study is as follows: How do Tilapia’s editorial cartoons visually construct and critique key national issues—such as economic hardship, environmental degradation, youth addiction, and political hypocrisy—in Ghanaian public discourse? Guided by an integrated theoretical framework from semiotics, visual rhetoric, and critical metaphor theory, the analysis reveals how cartoons use humour, caricature, exaggeration, and symbolic imagery to simplify complex realities and foster civic reflection. The study highlights how cartoons serve not only to entertain but also to hold power to account, amplify public concerns, and promote sociopolitical engagement. Through detailed visual analysis of ten selected cartoons, the paper underscores their capacity to critique governance, expose contradictions, and reflect collective sentiment—especially during election cycles. Overall, the research affirms the evolving role of visual satire as a potent medium of resistance, cultural expression, and democratic participation in Ghana. By bridging visual culture and critical discourse, the paper contributes to broader understandings of the role of the media in shaping public perception and fostering informed citizenship. Full article

Outdoor music festivals (OMFs) increasingly operate as a form of temporary land use that activates urban stock land, yet how such land-use reconfigurations unfold across uneven urban–rural geographies remains insufficiently examined. Taking China’s OMFs from 2013 to 2024 as a case, this study applies the Geodetector model within a spatial justice framework to analyze fifteen indicators organized along the distributional, procedural, and recognition dimensions. The results show a pronounced “market-sinking” trend accompanied by westward expansion, and the seasonal clustering gradually moderated. The three dimensions jointly shape OMFs’ diffusion through distinguishable pathways, with the procedural dimension exhibiting the highest explanatory power through institutional steering and industrial coordination, followed by the recognition dimension through demographic foundations and digital visibility, and the distributional dimension through material and infrastructural accessibility; interaction detection further indicates that their joint presence produces amplified effects. These mechanisms align with international land-use and territorial-governance studies, while reflecting the state-led coordination distinctive to China. The findings point to an emerging form of collaborative co-creation in which governmental, market, and community actors jointly shape the spatial production of cultural events, extending the classical core–periphery account and informing debates on the territorial governance of event spaces in non-metropolitan regions. Full article

Silica fume (SF) is a valuable industrial by-product for low-carbon cementitious systems, but it weakens early-age strength due to slow pozzolanic activation. To overcome this limitation and, crucially, to elucidate the influence of pore system geometry on macroscopic performance, graphene oxide (GO) was introduced as a modifying agent. Concurrently, the fractal dimension (D) of the pore network was adopted as a pivotal descriptor linking microstructure to macroscopic strength. Results show that GO compensates for the early strength loss caused by SF and further amplifies long-term gains by accelerating hydration and promoting gel continuity. SF reduces total porosity through filler and pozzolanic reactions, while GO dramatically increases geometric complexity of pores, producing the highest fractal dimension and the most refined pore structure in the matrix. Critically, the proposed log–log interaction model demonstrates that compressive strength is jointly controlled by porosity and fractal dimension, rather than porosity alone. Higher fractal dimension intensifies strength gains in low-porosity matrices by reflecting improved pore connectivity control and energy-dissipation pathways. This establishes fractal dimension as a powerful, mechanistically interpretable index for predicting performance and guiding structural design in SF–GO modified cementitious composites. Full article

This paper introduces a fully integrated gate-pole-dominant low-dropout regulator (LDO) that eliminates the need for external capacitors while sustaining high power-supply rejection (PSR) over a broad load current range. A loop-gain booster (LGB) is proposed to maintain the DC operating point of the error amplifier output at its optimal value, thereby preserving a high unity-gain frequency (UGF) even as the load current varies from zero to 200 mA. The parallel signal paths within the LGB inherently produce a left-half-plane (LHP) zero, which cancels one of the poles within the UGF of the feedback loop and guarantees robust stability under diverse operating conditions. Fabricated in a 40 nm CMOS technology, the prototype occupies only 0.008 mm² with a 4 pF on-chip compensation capacitor. The proposed LDO achieves a PSR of −72 dB at 1 MHz and −40 dB at 10 MHz when I_L = 200 mA and V_DO = 0.1 V, and maintains a PSR better than −78 dB at 1 MHz and −42 dB at 10 MHz when I_L = 1 mA and V_DO = 0.1 V. The LGB-enhanced regulator achieves excellent load and line regulation figures of 29 μV/mA and 0.75 mV/V, while the LGB itself consumes merely 7 μA out of a total quiescent current of 108 μA. Full article

Amplified Spontaneous Emission (ASE) sources are widely employed as highly stable broadband sources in fields such as high-precision navigation and optical detection. Erbium-doped fiber (EDF), as the core active component in ASE sources, has long been a key subject of thermal stability research. We fabricated a low-doped EDF with an 80 μm-cladding using the vapor phase doping (VPD) technique. This EDF was compared with a commercial 125 μm-cladding EDF using a double-pass forward (DPF) optical path configuration with a narrowband filter. We investigated the temperature-dependent characteristics of the ASE spectra generated by the two EDFs with different parameters. The temperature drift performance of the two EDFs was analyzed based on three critical indicators of the spectrum: mean wavelength, spectral bandwidth, and output power. In comparison with the commonly used EDF, the results show that a properly designed small-cladding EDF with an appropriate length can deliver higher ASE output power and exhibit a lower mean-wavelength temperature drift. This study provides an important guideline for promoting the miniaturization of high-precision fiber-optic sensing devices. Full article

A novel sense amplifier-based flip-flop (SAFF) is proposed for low-power operation. Since setup time is a key timing metric of a flip-flop, SAFF structures with near-zero setup time are advantageous for high-speed applications. However, reducing D-Q delay by increasing transistor size generally increases internal-node switching and power consumption. To address this trade-off, a conditional capture method using a modified NOR gate is proposed. The modified NOR gate compares D and Q and activates the sense amplifier only when required. As a result, unnecessary internal-node switching is reduced, leading to lower power consumption. In addition, unlike conventional conditional precharge sense amplifier-based flip-flop (CPSAFF), the proposed circuit does not require a separate setup time for precharge, which also helps reduce D-Q delay. The proposed circuit was implemented in the gpdk45nm process. Compared with CPSAFF, the proposed circuit achieved C-Q and D-Q delays of 89% and 66%, respectively, and PDP_D-Q values of 82%, 78%, and 75% at switching activities of 0.1, 0.5, and 1.0, respectively. These results indicate that the proposed circuit is suitable for low-power mobile applications with long standby periods. Full article

The atomic magnetometer (AM), operating within the spin-exchange relaxation-free (SERF) regime, boasts numerous advantageous qualities, including ultrahigh sensitivity, exceptional spatial resolution, and minimal power consumption. Consequently, it emerges as a promising alternative to superconducting quantum interference devices in biomagnetic measurement applications. This paper details the development of a fully integrated SERF AM system comprising a compact sensor head and corresponding control electronics. Utilizing a 4 mm × 4 mm × 4 mm cubic vapor cell, we have successfully integrated the compact sensor into a 9 ${\mathrm{cm}}^3$ volume employing a single-beam scheme facilitated by a polarization-maintaining fiber. The in-house control electronics encompass essential components, such as the laser driver, coil driver, vapor-cell temperature controller, and transimpedance amplifier. As a result, the fully integrated SERF AM achieves a sensitivity of 25 $\mathrm{fT}/{\mathrm{Hz}}^{1/2}$@5∼100 Hz, accompanied by a bandwidth of 193 Hz, meeting the necessary criteria for magnetocardiography (MCG) and magnetoencephalography (MEG) measurements. Furthermore, the fully integrated SERF AM successfully records typical MCG and alpha rhythm MEG signals, showcasing immense potential for biomagnetic imaging applications. Full article

This paper presents a nanowatt-scale operational transconductance amplifier (OTA) and an electronically tunable third-order low-pass filter (LPF) designed for energy-constrained biomedical signal conditioning. The circuits are implemented in a 65 nm CMOS process and verified through comprehensive schematic-level simulations. Biased in the deep subthreshold region at 1 nA, the OTA achieves a 50 dB low-frequency gain, a 225 Hz unity-gain bandwidth at 10 pF load capacitance and an input-referred noise floor of 1.55 μV/√Hz, with a total power consumption of only 1.75 nW. The integrated third-order LPF provides a wide tuning range (37–668 Hz) via bias current modulation, exhibiting excellent linearity with a THD of 0.059% and a 65.3 dB dynamic range. Monte Carlo and PVT corner analyses demonstrate the design’s theoretical robustness against process variations and environmental fluctuations. ECG signal simulations validate the circuit’s effectiveness in suppressing high-frequency artifacts while preserving morphological integrity, providing a proof-of-concept for ultra-low-power wearable healthcare architectures. Full article

This paper presents a flipped-voltage-follower low-dropout regulator (FVF-LDO) for power supply rejection enhancement and low-power operation in CMOS transimpedance amplifiers for optical receiver applications. The proposed FVF-LDO ensures high stability and reliable regulation over a wide range of load conditions by employing a flipped-voltage follower for fast local feedback and improved power supply rejection, while a super-source follower enhances the transient response through increased current-driving capability. A bandgap reference with a 3-bit trimming DAC is adopted to compensate process variations and support stable LDO operations, achieving a temperature coefficient of 19.6 ppm/°C over a wide range of −25 °C to 125 °C. The FVF-LDO exhibits a 101 mV undershoot under a 100 µA-to-10 mA load step with a 100 ns edge time. When applied to an optoelectronic inverter-based active-feedback transimpedance amplifier (TIA), the regulated supply improves the power supply rejection ratio (PSRR) from −6 dB to −38.3 dB. The proposed optoelectronic TIA realized in a 180 nm CMOS process achieves 67 dBΩ transimpedance gain, 869 MHz bandwidth, 66 dB dynamic range, 6.68 pA/√Hz input-referred noise current spectral density, and 4.68 mW power consumption from a single 1.8 V supply. The proposed TIA chip occupies a core area of 940 × 162 µm². Full article

Background/Objectives: The Black Caribbean population of Honduras, also referred to locally as Negro Inglés, constitutes one of the country’s nine recognized indigenous and Afro-descendant peoples. Predominantly settled in the Bay Islands and sections of the Caribbean coast, this community traces its ancestry predominantly to West Africa and has remained culturally and linguistically distinct for more than three centuries. Despite its demographic and historical relevance, no population-specific short tandem repeat (STR) database has been established for this group. Methods: Allele frequencies for 23 autosomal STR loci were characterized in 100 unrelated Black Caribbean individuals from the department of Islas de la Bahía. DNA was extracted from blood on FTA cards and amplified with the PowerPlex Fusion 6C System (Promega Corporation). Statistical parameters were computed using Genepop v4.2, Arlequin v3.5 and GDA v1.0. Results: A total of 241 distinct alleles were detected across all 23 loci (mean 10.48 ± 3.85 alleles/locus). Expected heterozygosity ranged from 0.6541 (D13S317) to 0.9350 (SE33), with a mean of 0.8150 ± 0.0664—values consistent with a population of predominantly West African origin. No locus exhibited a significant departure from Hardy–Weinberg equilibrium after Bonferroni correction (α = 0.0022). The combined power of discrimination exceeded 99.9999% and the combined chance of exclusion surpassed 99.9999%. Conclusions: This first genetic characterization of the Honduran Black Caribbean population delivers an essential, population-specific reference dataset for forensic casework, paternity testing, and population genetics research. The data also deepen the understanding of Afro-descendant genetic diversity in Central America and constitute a critical step towards equitable forensic genetic services for all Honduran ethnic communities. Full article

Blade impact faults degrade power generation quality, if not detected in time, may lead to turbine malfunction or even complete failure. Moreover, the accuracy of blade impact fault detection in tidal current turbine (TCT) is significantly affected by variations in flow velocity and tidal flow period. To solve this problem, a self-adaptive detection method based on stator current signals and k-nearest neighbor-multiplicative score (KNN-MS) is proposed. The method first employs the KNN algorithm to characterize local feature distributions. Then, robustness under unstable flow conditions is improved through variance-based weighting. Finally, a cumulative multiplicative scoring mechanism is proposed to amplify and quantify fault-related anomaly indicators. The experimental results show that the proposed method achieves high diagnostic accuracy and stability across steady, periodic, and variable-period flow scenarios. Full article

This paper presents a 13 W Ku-band GaN HEMT MMIC power amplifier employing a coupled-line interstage stabilization technique for radar sensor front-end applications. High-efficiency and stable power amplification in the Ku-band is essential for radar sensing systems, where low-frequency instability and process sensitivity often limit multistage GaN amplifier performance. To address these challenges, a coupled-line interstage network is introduced instead of conventional series capacitors and parallel RC stabilization circuits. The proposed structure effectively suppresses low-frequency gain while maintaining RF performance and improving robustness against process variations due to its planar transmission-line implementation. The two-stage power amplifier was fabricated using a 0.25 μm commercial GaN HEMT MMIC process. For compact implementation, the coupled-line structure was realized in a meandered layout and verified through full electromagnetic simulations. Measured small-signal results show a gain (S21) of 18.6–21.6 dB, with input and output return losses (S11 and S22) of −3.3 to −10.2 dB and −4.4 to −7.2 dB, respectively, over 13.5–16 GHz. Large-signal measurements demonstrate a saturated output power of 40.7–41.5 dBm and a power-added efficiency of 21.3–28.1% across the same frequency range. The fabricated MMIC achieved stable operation without oscillation, validating the effectiveness of the proposed coupled-line stabilization approach for Ku-band radar sensor systems. Full article