Miracle-dz/UniFAR-FTUs huggingface dataset:
Real-Time and DSP-Free 128 Gb/s PAM-4 Link Using a Binary Driven Silicon Photonic Transmitter

Optical transmitters for four-level pulse amplitude modulation (PAM-4) have attracted a significant amount of research in recent years, in large part due to the standardization of the format for the 200 and 400 Gigabit Ethernet optical interconnects in data centers. However, combining low-power and linear operation of the electro-optical frontend with sufficiently large bandwidths has proven challenging, especially for the 100 Gb/s/λ links (i.e., employing 50 Gbaud PAM-4). The most straightforward solution has been to deal with the non-idealities of the modulator in the electrical domain: predistorting the signal levels and/or equalizing the frequency response with the help of digital signal processing (DSP). However, this typically requires fast digital-to-analog converters (DACs), either capable of delivering large swings (> 1 Vpp) or supplemented with an additional linear amplifier to drive the optical modulator. Both options substantially increase the power consumption and the complexity of the transceiver. Rather than allocating effort to linearize the electrical to optical conversion of a single modulator, we propose a topology that performs the DAC operation in the optical domain. Two compact electro-absorption modulators in an interferometer layout are driven with NRZ data to generate the four-level signal in the optical domain. Using this topology, we demonstrate the first real-time 128 Gb/s PAM-4 transmission with a silicon photonic transmitter in a chip-to-chip link. In a back-to-back setup, we obtained a bit-error ratio (BER) of 4 × 10−10 without requiring any DAC, DSP, or modulators with large traveling wave structures. Over 1 km of standard single mode fiber a BER of 8 × 10−6 is recorded, still well below the KP4 forward error-coding limit. These results correspond to the lowest BERs reported for any real-time PAM-4 link at 100 Gb/s or higher, illustrating the benefit of performing the DAC operation in the optical domain.
Recombination Analysis of Tunnel Oxide Passivated Contact Solar Cells

In this paper, an analytical model has been developed to observe the recombination losses involved in a tunnel oxide passivated contact solar cell with a carrier-selective layer constituting polycrystalline silicon (poly-Si). The main focus of this paper is to observe the contribution of each component of recombination current density and its effect on open-circuit voltage, V<sub>oc</sub>. The effect of emitter saturation current density (J<sub>oe</sub>), surface recombination velocity, substrate thickness, and doping density of carrier-selective layer on V<sub>oc</sub> has been presented. The analysis indicates that V<sub>oc</sub> = 766 mV can be achieved for J<sub>oe</sub> = 2 fA/cm<sup>2</sup>, and a doping density of poly-Si > 10<sup>21</sup>cm<sup>−3</sup> in a c-Si/SiO<sub>2</sub>/poly-Si contact for a 50-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula>-thick substrate in case of ideal surface passivation. For identical conditions, V<sub>oc</sub> attains a lower value of 750mV for a 180-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula>-thick substrate. The dependence of V<sub>oc</sub> on bandgap of tunnel layers has also been observed by considering other materials like Si<sub>3</sub>N<sub>4</sub> and SiC. These results from the analyticalmodel have been compared with results froma simulation using automat FOR simulation of HETerostructures v2.5 and have been found to be in good agreement with each other.
Hydrologic and Agricultural Earth Observations and Modeling for the Water-Food Nexus

In a globalizing and rapidly-developing world, reliable, sustainable access to water and food are inextricably linked to each other and basic human rights. Achieving security and sustainability in both requires recognition of these linkages, as well as continued innovations in both science and policy. We present case studies of how Earth observations are being used in applications at the nexus of water and food security: crop monitoring in support of G20 global market assessments, water stress early warning for USAID, soil moisture monitoring for USDA’s Foreign Agricultural Service, and identifying food security vulnerabilities for climate change assessments for the UN and UK international development agency. These case studies demonstrate that Earth observations are essential for providing the data and scalability to monitor relevant indicators across space and time, as well as understanding agriculture, the hydrological cycle, and the water-food nexus. The described projects follow the guidelines for co-developing useable knowledge for sustainable development policy. We show how working closely with stakeholders is essential for transforming NASA Earth observations into accurate, timely, and relevant information for water-food nexus decision support. We conclude with recommendations for continued efforts in using Earth observations for addressing the water-food nexus and the need to incorporate the role of energy for improved food and water security assessments.
A Mathematical Framework of Optimal Number of Clusters in 3D Noise-Prone WSN Environment

In this paper an analytical model of the optimal number of clusters and the corresponding optimal probability are derived for different types of 3D WSN settings utilizing single-hop homogeneous LEACH protocol. Three types of 3D network configurations are analyzed. These include cube, cylinder and sphere network configurations. Energy analysis of these network configurations is done in noise-prone communication environment. The noise is modelled utilizing the probability of reception <inline-formula> <tex-math notation="LaTeX">$p_{r}$ </tex-math></inline-formula>. A small value of <inline-formula> <tex-math notation="LaTeX">$p_{r}$ </tex-math></inline-formula> indicates more packets are dropped, which is a sign of large noise. It was shown through analysis and simulation that optimal number of clusters, optimal probability and energy consumption are affected by the geometry of the 3D WSN, noise, and transmission amplification model used.
Relationship Bonds and Service Provider’s Emotional Labor: Moderating Effects of Collectivism

Since service providers directly conduct emotional labor to customers, it is important to identify the factors influencing emotional labor of service providers. Even though the studies identifying the predisposing factors influencing emotional labor are taking place, there is no empirical evidence confirming how relationship bonds, which have been established between corporations and service providers, are related to emotional labor. This study examined the influences of relationship bonds on emotional labor through person-organization fit (P-O fit) and the moderating effects of collectivism between P-O fit and emotional labor. Analysis was conducted by performing questionnaire surveys targeting 350 employees in the financial industry. As a result of the analysis, it has been found that financial bonds, social bonds, and structural bonds enhanced P-O fit and P-O fit improved deep acting. In addition, this study identified that collectivism of service providers strengthened the influence of P-O fit toward deep acting. This study not only suggested the empirical evidence identifying the process of relationship bonds influencing emotional labor but also expanded the scope of study by examining moderating roles of collectivism in cultural psychology aspect.
Evaluation of Low-Temperature Saturation Velocity in  $\beta$ -(AlxGa1–x)2O3/Ga2O3 Modulation-Doped Field-Effect Transistors

We report on the high-field transport characteristics and saturation velocity in a modulation-doped <inline-formula> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-(Al<sub>x</sub>Ga<sub>1–x</sub>)<sub>2</sub>O<sub>3</sub>/Ga<sub>2</sub>O<sub>3</sub> heterostructure. The formation of a 2-D electron gas (2DEG) in the modulation-doped structure was confirmed from the Hall measurements, and the 2DEG channel mobility increased from 143 cm<inline-formula> <tex-math notation="LaTeX">$^{2}/\text{V}\cdot \text{s}$ </tex-math></inline-formula> at room temperature to 1520 cm<inline-formula> <tex-math notation="LaTeX">$^{2}/\text{V}\cdot \text{s}$ </tex-math></inline-formula> at 50 K. The high electron mobility at 50 K made it feasible to achieve velocity saturation inside the channel. The saturation velocity was estimated based on both pulsed current–voltage measurements and small-signal radio frequency (RF) measurements. The measured velocity–field profile suggested a saturation velocity above <inline-formula> <tex-math notation="LaTeX">$1.1\times 10^{7}$ </tex-math></inline-formula> cm/s at 50 K. The small-signal RF characteristics were measured for the fabricated modulation-doped field-effect transistors with a Pt-based Schottky contact. The current gain cutoff frequency (<inline-formula> <tex-math notation="LaTeX">$\text{f}_{\text {t}}$ </tex-math></inline-formula>) and maximum oscillation frequency (<inline-formula> <tex-math notation="LaTeX">$\text{f}_{\text {max}}$ </tex-math></inline-formula>) showed significant increases from 4.0/11.8 GHz at room temperature to 17.4/40.8 GHz at 50 K for the device with gate length of <inline-formula> <tex-math notation="LaTeX">$\text{L}_{{\textsf {G}}} = 0.61\,\,\mu \text{m}$ </tex-math></inline-formula>. The analysis of the low temperature <inline-formula> <tex-math notation="LaTeX">$\text{f}_{\text {t}}$ </tex-math></inline-formula> based on device simulations indicated a peak velocity of <inline-formula> <tex-math notation="LaTeX">$1.2\times 10^{7}$ </tex-math></inline-formula> cm/s. The three-terminal off-state breakdown measurement further suggested an average breakdown field of 3.22 MV/cm. The high saturation velocity and high breakdown field in <inline-formula> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-Ga<sub>2</sub>O<sub>3</sub> make it a promising candidate for high-power and high-frequency device applications.
FlipTracer: Practical Parallel Decoding for Backscatter Communication

With parallel decoding for backscatter communication, tags are allowed to transmit concurrently and more efficiently. Existing parallel decoding mechanisms, however, assume that signals of the tags are highly stable and, hence, may not perform optimally in the naturally dynamic backscatter systems. This paper introduces FlipTracer, a practical system that achieves highly reliable parallel decoding even in hostile channel conditions. FlipTracer is designed with a key insight; although the collided signal is time-varying and irregular, transitions between signals’ combined states follow highly stable probabilities, which offers important clues for identifying the collided signals and provides us with an opportunity to decode the collided signals without relying on stable signals. Motivated by this observation, we propose a graphical model, called one-flip-graph (OFG), to capture the transition pattern of collided signals, and design a reliable approach to construct the OFG in a manner robust to the diversity in backscatter systems. Then, FlipTracer can resolve the collided signals by tracking the OFG. We have implemented FlipTracer and evaluated its performance with extensive experiments across a wide variety of scenarios. Our experimental results have shown that FlipTracer achieves a maximum aggregated throughput that approaches 2 Mb/s, which is $6\times $ higher than the state of the art.
Multichannel data for understanding cognitive affordances during complex problem solving

This exploratory study challenges the current practices in cognitive load measurement by using multichannel data to investigate cognitive load affordances during online complex problem solving. Moreover, it is an attempt to investigate how cognitive load is related to strategy use. Accordingly, in the current study a well- and an ill-structured problem were developed in a virtual learning environment. Online support was provided. Participants were 15 students from the teacher training program. This study incorporated subjective measurements of students' cognitive load (i.e., intrinsic, extraneous, germane load and their mental effort) combined with physiological data containing galvanic skin response (GSR) and skin temperature (ST). A first aim was to investigate whether there was a significant difference for the subjective measurements, physiological data and consultation of support between the well-and ill-structured problem. Secondly this study investigated how individual differences of subjective measurements are related to individual differences of physiological data and consultation of support. Results reveal significant differences for intrinsic load, mental effort between a well- and ill-structured problem. Moreover, when investigating individual differences, findings reveal that GSR might be related to mental effort. Additionally, results indicate that cognitive load influences strategy use. Future research with larger sample sizes should verify these findings in order to have more insight into how we can measure cognitive load and how its related to self-directed learning. These insights should allow us to provide adaptive support in virtual learning environments.
Evaluating the performance and neutrality/bias of search engines

Different search engines provide different outputs for the same keyword. This may be due to different definitions of relevance, to different ranking aggregation methods, and/or to different knowledge/anticipation of users' preferences, but rankings are also suspected to be biased towards own content, which may prejudicial to other content providers. In this paper, we make some initial steps toward a rigorous comparison and analysis of search engines, by proposing a definition for a consensual relevance of a page with respect to a keyword, from a set of search engines. More specifically, we look at the results of several search engines for a sample of keywords, and define for each keyword the visibility of a page based on its ranking over all search engines. This allows to define a score of the search engine for a keyword, and then its average score over all keywords. Based on the pages visibility, we can also define the consensus search engine as the one showing the most visible results for each keyword, and discuss how biased results toward specific pages can be highlighted and quantified to provide answers to the search neutrality debate. We have implemented this model and present an analysis of the results.
Improving Grid-Based Location Prediction Algorithms by Speed and Direction Based Boosting

Grid-based location prediction algorithms are widely researched and evaluated. These algorithms usually integrate the speed and the direction during the learning process as regular contextual features, for example, like the time of the day or the day of the week. Unfortunately, the way speed and direction are currently used does not fulfill their potential. In this paper, we propose an alternative approach for integrating the user’s current speed and direction in a post-processing mechanism that highly improves the algorithms’ accuracy. We dynamically update the probabilities of the predictions provided by the existing (base) algorithms by dividing the surface into four areas while boosting the probabilities in some areas and reducing the probabilities in others. We evaluated our method on three well-known grid-based location prediction algorithms and two different datasets and were able to show that our method improves the predictions made solely by the algorithms. Our improvement was stable during the entire experiment for long-term predictions and for greater prediction distances, particularly in the cold start phase which is considered more difficult to improve.
A Two-Bit Precision Decoding Algorithm for LDPC Codes Over the Binary Symmetric Channel

The min-sum algorithm as an approximation of the sum-product algorithm (SPA) for decoding of LDPC codes has much lower computational complexity, but slightly worse performance than the SPA. However, severe performance degradation might occur when it is realized in hardware due to the finite precision effect, especially in two-bit precision. In order to overcome this problem, we propose a two-bit precision decoding algorithm. The proposed algorithm employs one of several decoders adaptively, based on the syndrome weight of the estimated decoder output every iteration. Numerical results show that it has similar performance to the SPA over the binary symmetric channel.
DOTA: Physical-Layer Decomposing and Threading for ZigBee/Wi-Fi Co-Transmission

The ever-increasing deployment of Wi-Fi and ZigBee networks aggravates cross-technology interference (CTI) in the 2.4 GHz unlicensed spectrum. This letter presents a clean-slate technique, DOTA, to combat the CTI and enable ZigBee/Wi-Fi co-transmission. Unlike existing solutions merely handling Wi-Fi-to-ZigBee interference, DOTA accounts for the true sense of CTI wherein ZigBee and Wi-Fi interfere with each other. At the heart of DOTA lies two operations, signal polishing and pulse disambiguation, for decomposing and threading signal samples to recover contaminated ZigBee and Wi-Fi signals. Experiment results validate the feasibility of superiority of DOTA.
Discrete-Time Selfish Routing Converging to the Wardrop Equilibrium

This paper presents a discrete-time distributed and noncooperative routing algorithm, which is proved, via Lyapunov arguments, to asymptotically converge to a specific equilibrium condition among the traffic flows over the network paths, known as Wardrop equilibrium. This convergence result improves the discrete-time algorithms in the literature, which achieve approximate convergence to the Wardrop equilibrium. Numerical simulations show the effectiveness of the proposed approach.
A Novel Energy-Coupling-Based Hierarchical Control Approach for Unmanned Quadrotor Transportation Systems

Cable-suspended transportation is an important way of transferring goods and materials by rotorcraft in complex and hazardous environments, where external disturbances, system uncertainties, and, especially, the underactuated characteristic bring great challenges to realize safe and smooth deliveries. In terms of the aforementioned problems, this paper presents an enhanced coupling hierarchical control scheme for both quadrotor positioning and payload swing elimination. By exploiting the cascade property of quadrotor transportation systems, we can design controllers for the inner loop and the outer one separately, provided that the growth restriction condition is well satisfied, which greatly simplifies the design procedure. As the outer loop describes the quadrotor translation and payload swing motion, our central work focuses on the controller design of this subsystem. Specifically, a generalized payload signal is introduced to increase the state coupling, based on which we construct a novel energy storage function. Consequently, an energy coupling control law is proposed, which ensures that the equilibrium point of the system is asymptotically stable by using Lyapunov techniques and LaSalle's invariance theorem. Experimental results are presented to illustrate the superior control performance, even in the presence of external disturbances and parameter uncertainties.
Relay-Aided Request-Aware Distributed Packet Caching for Device-to-Device Communication

To improve the data retrieval performance of device-to-device (D2D) communication, the impact from the various concentration levels of packet requests from different user equipment (UE) groups should be considered. However, few existing works incorporate this aspect in system design. In this letter, we propose a new distributed D2D relay-aided packet caching scheme, which exploits the properties of the diverse packet requests and requirements of physical link success among different UE groups. Theoretical optimal solution to the packet caching problem and several properties of its influencing factors are studied, showing that the system performance can be improved by exploiting the so-called packet request diversity. Simulation results validate our analyses and demonstrate the benefits of the proposed scheme.
Programmable Deformations of Networked Inflated Dielectric Elastomer Actuators

Soft actuators play an indispensable role in producing motions of soft robots. Dielectric elastomer actuators coupled with a fluid/air mass have proved to undergo considerable voltage-induced deformation. To achieve large deformation, a dominant way is to trigger snap-through instability, but the induced instantaneous deformation is not continuously stable, resulting in a limited space for control. This paper proposes a network of inflated dielectric elastomer actuators, interconnected via a chamber, with the advantages to be not only highly deformable but also continuously controllable. Herein, the snap-through instability is suppressed by the initial in-plane prestretch (set to be 3), and the networked design enlarges the actuation range by modulating the inner pressure to postpone material failures. With a large and continuous actuation space, an array of the networked actuators can present programmable deformations. We investigate how to compute the required input voltages for programming desired deformations. We further carry out experiments to show different deformation patterns. This paper represents an important step toward the integration and network of numerous soft actuators, and the potential applications may span shape display and distributed actuation for soft robots.
Design of High Torque Density Multi-Core Concentrated Flux-Type Synchronous Motors Considering Vibration Characteristics

This paper proposes a novel structure for the concentrated flux-type synchronous motor (CFSM) in order to improve the torque density, as well as the vibration characteristics. First, the conventional surface-mounted permanent magnet synchronous motor as prototype for the electric booster in the brake system is investigated through tests. Then, the relationship between the vibration characteristics and the number of poles and slots is analyzed. Based on the analysis results, a pole–slot combination for an improved CFSM is determined to enhance the vibration characteristics. Furthermore, a novel structure for the improved motor that employs three different core shapes in the rotor is proposed to increase the torque density. As a result, the improved motor with excellent vibration characteristics as well as a high torque density is designed. Finally, experiments are conducted to verify the effectiveness and the feasibility of the proposed method.
A Spread-Spectrum Mode Enabled Ripple-Based Buck Converter Using a Clockless Frequency Control

Current-mode ripple-based dc–dc converters have become a widely adopted topology due to their inherent advantages of improved dynamic transient response along with a simple current sensing scheme. However, the switching frequency of such converters is a function of the converter’s duty cycle and inherent circuit delays. In this brief, a novel frequency control of a buck converter is proposed through the implementation of a frequency-to-voltage converter that obviates the need for an external clock, and enables both fixed-switching frequency (<inline-formula> <tex-math notation="LaTeX">${F} _{\textbf {SW}}$ </tex-math></inline-formula>) and spread-spectrum modes of operation. A current-mode ripple-based buck converter is implemented in a 180-nm CMOS process for an input voltage of 2.8–4.2 V, output voltage range of 1.3–2.2 V, and load current range of 40–200 mA. In fixed-<inline-formula> <tex-math notation="LaTeX">${F} _{\textbf {SW}}$ </tex-math></inline-formula> mode, a peak efficiency of 89.4% was achieved at an input voltage of 3.8 V, load current of 200 mA and 1.8 V output voltage, while in spread-spectrum mode, a peak efficiency of 88.2% was achieved for similar conditions. Additionally, in spread-spectrum mode, a 19-dB reduction in peak noise power is observed in the output at the fundamental frequency.