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Electronic transport properties of Janus Ge2PAs monolayer: a prototype 2D metal-semiconductor-metal device
Get PDFThe semiconductor industry’s quest for miniaturization has driven the exploration of new materials and innovative designs. Among these, two-dimensional (2D) semiconductor materials have emerged as promising candidates due to their unique electrical conductivity and superior carrier transport properties, which address the limitations of conventional bulk semiconductors at the nanoscale. Understanding the electronic transport properties of 2D materials is essential for unlocking their full potential in emerging nanoelectronic applications. In this context, our study focuses on the transport characteristics of Janus Ge 2 PAs monolayer-based metal-semiconductor-metal (MSM) devices. Utilizing DFT (density functional theory) simulations coupled with the nonequilibrium Green’s function method, we explore the effects of external factors, such as channel length and electrode doping concentration on device performance in the ballistic region (sub-10 nm). By modeling two-probe MSM nanodevices, we analyze transmission coefficients [ T ( E ) ] under varying bias voltages and study the I-V characteristics’ dependence on channel lengths and doping concentrations. Our findings provide valuable insights into the electronic transport properties of the Janus Ge 2 PAs monolayer and offer guidance for the design and optimization of 2D material-based nanoelectronic devices
Absorption loss modeling tools for terahertz band drone communications
Get PDFThis paper compares the following four Terahertz (THz) band molecular absorption loss modeling tools: International Telecommunication Union (ITU)-R P.676 model, Line-by-Line Radiative Transfer Model (LBLRTM), Atmospheric Model (am), and HITRAN on the Web (HotW). We evaluate the THz band drone communication tools under horizontal and vertical communication scenarios. We use the U.S. Standard 1976 and tropical weather profiles to generate path loss data across different altitudes, frequencies, and distances. We also employ a simple analytical model, fitting the data from the ITU, LBLRTM, and am tools to assess its accuracy in predicting path loss. Our results demonstrate high consistency among the tools, with path loss differences becoming more significant in vertical scenarios. This study provides the first comprehensive comparison of four widely used molecular absorption loss modeling tools for THz band drone communications, considering various scenarios and weather conditions
A 24-30-GHz modified Gilbert-Cell downconverter with high linearity and isolation
No full textThis paper introduces a downconverter mixer employing a modified double-balanced Gilbert-cell topology, designed using IHP's 0.13- (Formula presented.) m SiGe BiCMOS technology. Distinct from the conventional topology, a resonator was employed at the emitter of the transconductance stage, which enables the utilization of transconductance stage as an active balun, allowing for direct feeding of the single-ended input without sacrificing the advantageous of the double-balanced topology. The integration of the resonator reduces the amplitude and phase errors within the active balun segment, thereby enhancing port-to-port isolation. The area occupied by the resonator is approximately 1.7 times smaller than that of an RF transformer balun typically employed in conventional double-balanced topologies. The LO and IF differential signals are converted to single-ended ones through transformer baluns for measurement purposes. The frequencies of operation for RF, LO, and IF are 24–30, 18–24, and 6 GHz, respectively. The conversion loss is 7.7 dB at 26 GHz, with port-to-port isolations exceeding 35 dB. The input 1-dB compression point is 5.7 dBm, while the circuit consumes 65-mW power from a 3.3-V voltage supply. Excluding the pads, the active area of the design spans 1 mm2
Enhancing PEM fuel cell performance and durability with CeO2-Modified Fe-N-C hollow-fiber cathodes
No full textIn this study, Fe-N-C catalyst-based hollow-fiber cathodes were fabricated via a core-shell electrospinning technique to increase surface area, promote uniform catalyst and Nafion® distribution, and achieve highly conductive and porous cathode structures for proton exchange membrane (PEM) fuel cells. Morphological analysis confirmed the successful fabrication of Fe–N–C hollow-fiber cathodes with a highly porous structure, as verified by porosimetry. Membrane electrode assemblies (MEAs) incorporating these cathodes (3.0 mg.cm-2 Fe-N-C) were evaluated for fuel cell performance and durability and compared to MEAs using air-sprayed and single-fiber cathodes. The effect of cerium oxide (CeO2) as a radical scavenger was also investigated to improve durability of the electrode. Among the tested configurations, hollow-fiber cathodes with CeO2 exhibited superior performance, achieving a peak power density of 96.1 mW.cm-2 at end-of-test (EOT) with a 14.4 % improvement compared to CeO2-free cathode. Single-fiber cathodes with CeO2 also showed enhanced performance, attributed to reduced hydrogen peroxide (H2O2) formation. Electrochemical impedance spectroscopy (EIS) confirmed the role of CeO2 in suppressing H2O2 formation, thereby improving both performance and durability. These results highlight the potential of CeO2-modified Fe–N–C hollow-fiber cathodes as promising cathode materials for PEM fuel cells
Distance transform guided mixup for Alzheimer's detection
No full textAlzheimer's detection efforts aim to develop accurate models for early disease diagnosis. Significant advances have been achieved with convolutional neural networks and vision transformer based approaches. However, medical datasets suffer heavily from class imbalance, variations in imaging protocols, and limited dataset diversity, which hinder model generalization. To overcome these challenges, this study focuses on single-domain generalization by extending the well-known mixup method. The key idea is to compute the distance transform of MRI scans, separate them spatially into multiple layers and then combine layers stemming from distinct samples to produce augmented images. The proposed approach generates diverse data while preserving the brain's structure. Experimental results show generalization performance improvement across both ADNI and AIBL datasets
RGB-D camera-enabled digital twin dataset for education
No full textThe concept of a Digital Twin originated in 1997, but its foundations date back to the simulations created by NASA for space missions in the 1960s. Although it did not gain significant attention compared to other fields of computer science for many years, Digital Twin technology has experienced a resurgence in interest, particularly following the COVID-19 pandemic, which highlighted the importance of online education. By identifying students' focal points, we can enhance the quality and efficiency of education. It is essential to simulate such scenarios within digitally created environments, like labs and classrooms, and analyze these scenarios based on where and for how long students focus their attention. To achieve this, the Intel RealSense D435i, a modern RGB-D camera, was utilized to collect real-world data for the digital environment. This camera's depth measurement capabilities enable the accurate digital representation of labs, classrooms, and meeting rooms, facilitating the testing of real-world scenarios. The point cloud data obtained from the camera was processed using MeshLab and imported into the Unity environment for animation creation. These animations will be capable of detecting where students are looking in real time, resulting in the compilation of a "gaze line"dataset that illustrates where and for how long students focus their attention, ultimately enabling the development of realistic animations. The data and appendix will be available at: https://7unahan.github.i
Medium acces control with optimal beamwidth adjustment for THz band drone communications
No full textWith the growth in wireless data traffic, Terahertz (THz)-band communication has emerged as a promising technology to enable ultra-high-speed wireless networks. However, THz communication faces unique challenges such as high path loss, molecular absorption, and severe misalignment. In this paper, we propose a Medium Access Control (MAC) protocol for THz-band drone-to-drone (Dr2Dr) communication, building upon the Adaptive Directional Antenna Protocol for THz networks (ADAPT) framework, where we integrate an optimal beamwidth adjustment (OBA) algorithm that dynamically optimizes the beamwidth to overcome the misalignment issues and increase communication reliability. The proposed protocol leverages the 3-way handshake mechanism to estimate node positions and adapts the beamwidth accordingly, maximizing directional gains. Through extensive simulations, we have demonstrated that our method improves throughput and reduces delay compared to ADAPT without OBA
Globalism and its discontents: a case study of two Turkish MNCs between globalism and nationalism
No full textAfter crackdown, is Turkey an autocracy?
No full textTurkey’s president would rather turn his country into a full autocracy than give up power. But the Turkish people are clinging to what remains of their democracy, and they are ready to fight for it
Optimal interventions when illicit trafficking responds
No full textThe capabilities of illicit trafficking organizations to expand or contract their periphery and source segments by modifying their link structures pose challenges to law enforcement. This paper scrutinizes the structural response of illicit trafficking organizations to intervention strategies. It also studies how the law enforcement authority should allocate its resources between the source and the periphery segments, given the structural response of trafficking, to minimize the expected harms. The analysis shows that traffickers integrate the supply, possibly build redundant sources and expand in peripheral markets if the source segment is targeted (decapitation), maintain near-maximal expansion by splintering into supply cells or thin subnetworks if the periphery is targeted (amputation). This response subverts law enforcement primarily by suppressing the possibility of trace-back detection of trafficking units through their detected connections. In the transnational trafficking context, it can also stifle intelligence sharing between nations. The optimal intervention, then, is amputation under intermediate budgets and large source fragmentation costs, decapitation under low detection contiguity. Actual policies that prioritize border protection and port-of-entry units can be optimal from national, but not global, perspective