Synchronous Channel Research Articles

Numerical Comparative Investigating of PEMFC with Novel Hybrid Zigzag Channels: Reaction, Transport and Drainage Enhancements

The impact of flow channel design on mass transport and drainage in proton exchange membrane fuel cells (PEMFCs) is significant, thereby influencing the reaction rate. Based on conventional wavy design, this study introduces two novel hybrid zigzag flow channels (asynchronous and synchronous) with both zigzag sidewalls and bottom wall, aiming in further improving mass and heat transfer, as well as drainage capacity to achieve better fuel cell performance. Numerical simulations demonstrate that the net power densities of both asynchronous and synchronous hybrid zigzag channels show a 28.7% and 44.4% improvement at low voltage, respectively. The implementation of the asynchronous hybrid zigzag flow channel has been observed to result in a notable reduction in pressure drop, amounting to 9.2%, while concurrently enhancing power output by 10.7% in comparison to a conventional zigzag channel. Additionally, the novel hybrid zigzag designs improve mass transfer efficiency at high current density and exhibits better temperature distribution uniformity. Moreover, the volume of fluid simulations illustrate that hybrid zigzag channels are highly effective in removing accumulated water, surpassing the straight channel with a drainage rate exceeding 54%, as well as a lower surface liquid coverage.

Free‐space quantum key distribution transmitter system using WDM filter for channel integration

AbstractIn this study, we report a transmitter system for free‐space quantum key distribution (QKD) using the BB84 protocol, which does not require an internal alignment process, by using a wavelength‐division multiplexing (WDM) filter and polarization‐encoding module. With a custom‐made WDM filter, the signals required for QKD can be integrated by simply connecting fibers, thus avoiding the laborious internal alignment required for free‐space QKD systems using conventional bulk‐optic setups. The WDM filter is designed to multiplex the single‐mode signals from 785‐nm quantum and 1550‐nm synchronization channels for spatial‐mode matching while maintaining the polarization relations. The measured insertion loss and isolation are 1.8 dB and 32.6 dB for 785 nm and 0.7 dB and 28.3 dB for 1550 nm, respectively. We also evaluate the QKD performance of the proposed system. The sifted key rate and quantum bit error rate are 1.6 Mbps and 0.62%, respectively, at an operating speed of 100 MHz, rendering our system comparable to conventional systems using bulk‐optic devices for channel integration.

Integrated multi-proxy source-to-sink analysis of Late Barremian (Lower Cretaceous) clastic systems in the Essaouira-Agadir Basin

This study investigates the provenance of the continental and marine Late Barremian clastics of the Bouzergoun Formation, exposed in the Essaouira-Agadir Basin (EAB). Thin section petrography, Scanning Electron Micrography, heavy minerals analysis, and detrital zircon dating were conducted and integrated with a large dataset of published Low-Temperature Thermochronology (LTT) studies to reconstruct the associated source-to-sink system(s). The results constrain the source and size of the system, and composition of deposited clastics, and investigate the mechanism for delivery of coarse clastics into the offshore domain, a key target for hydrocarbon exploration.The homogeneity of rock composition fingerprints throughout the basin indicates a common provenance for both the northern and southern studied transects. Hinterland analysis based on LTT data identifies the Western Meseta and Massif Ancien de Marrakech (MAM) regions as the only possible source candidates exhuming during the Late Barremian, confirmed by detrital zircon geochronology. Heavy mineral populations reveal partly recycled sediment including a probable igneous source. Rock fragment populations comprise limestones, sandstones, and volcanic composition, which correlate with lithologies of the MAM.The integration of all data suggests a best-fit model for the Late Barremian of a source-to-sink system of moderate size (200–300 km long), dominantly sourced from the MAM (western High Atlas). This provided a sand-rich mix of sediment resulting from the erosion of exhuming Triassic continental basins, with associated clays from the weathering of basalts and Triassic/Jurassic mudstones.Late Barremian eustatic sea level fall, together with regional uplift in the hinterland, is interpreted to have resulted in a forced regression that allowed the system to prograde towards the slope margin, offering enhanced potential for sand delivery into the deep offshore domain. Seismic imaging offshore provides tentative interpretation of synchronous high reflectivity deepwater channels located in structural lows controlled by diapiric salt movement.The Mesetian domain was likely undergoing denudation at the same time and shedding clastic-rich sediments to the northern part of the EAB, beyond the studied region. Sediment supply from the MAM may be mixed with the Mesetian sands to the northern part of the EAB and tentatively in the offshore Essaouira.

Research on a Multi-Channel High-Speed Interferometric Signal Acquisition System

In order to capture the large-scale interferometric signal generated by the space-borne interferometric infrared Fourier spectrometer (IRIFS) in real time, and overcome the limitations of insufficient sampling rate, transmission rate, and significant signal noise in current equipment, a multi-channel high-speed acquisition system for large-scale interferometric signals is designed. A high-performance analog-to-digital converter (ADC) oversampling scheme is designed, which can realize up to 8 synchronous acquisition channels and has a maximum sampling rate of 125 Msps/Ch to ensure the acquisition of interferometric signals. The scheme of jesd204b inter-board transmission and optical fiber terminal transmission is designed. The inter-board transmission rate is 12.5 Gbps, and the terminal transmission rate is 10 GB/s to ensure high-speed data transmission. A hardware filter is designed to realize spatial noise processing of interference signals and ensure the accuracy of acquisition results. The dynamic performance of the data acquisition (DAQ) card is analyzed using discrete Fourier transform in the frequency domain. The spurious free dynamic range (SFDR) is 84 dB, the signal-to-noise ratio (SNR) is 72.7 dB, and the cross-talk is −81.6 dB, which verifies the dynamic stability of the DAQ card. Finally, the infrared radiation in real space is measured. The average ΔNESR of long wave reaches 48 mW∗m−2∗sr−1, and the average ΔNESR of medium wave reaches 12.3 mW∗m−2∗sr−1, which verifies the reliability of the system performance. The system is of great significance for large-scale infrared interferometric signal acquisition, and has strong practical application value in multi-channel synchronization, real-time high-speed acquisition, and high-speed data transmission.

Skin-Interfaced Bifluidic Paper-Based Device for Quantitative Sweat Analysis.

The erratic, intermittent, and unpredictable nature of sweat production, resulting from physiological or psychological fluctuations, poses intricacies to consistently and accurately sample and evaluate sweat biomarkers. Skin-interfaced microfluidic devices that rely on colorimetric mechanisms for semi-quantitative detection are particularly susceptible to these inaccuracies due to variations in sweat secretion rate or instantaneous volume. This work introduces a skin-interfaced colorimetric bifluidic sweat device with two synchronous channels to quantify sweat rate and biomarkers in real-time, even during uncertain sweat activities. In the proposed bifluidic-distance metric approach, with one channel to measure sweat rate and quantify collected sweat volume, the other channel can provide an accurate analysis of the biomarkers based on the collected sweat volume. The closed channel design also reduces evaporation and resists contamination from the external environment. The feasibility of the device is highlighted in a proof-of-the-concept demonstration to analyze sweat chloride for evaluating hydration status and sweat glucose for assessing glucose levels. The low-cost yet highly accurate device provides opportunities for clinical sweat analysis and disease screening in remote and low-resource settings. The developed device platform can be facilely adapted for the other biomarkers when corresponding colorimetric reagents are exploited.

Synchronous and zwitter-ion channels of (<i>R</i>)-5-methyl2-(1-methylethylidene)-cyclohexanone reaction with 4-phenyl-4<i>H</i>-1,2,4-triazoline-3,5-dione

The interaction of pulegone with enophil - 4-phenyl-4 H -1,2,4-triazoline-3,5-dione leads to the formation of two described earlier epimers: 1-[(1 R ,4 R )-4-methyl-1-(1-methylethenyl)-2-oxocyclohexyl]-4-phenyl-1,2,4-triazolidine-3,5-dione ( RR -isomer) and 1-[(1 S ,4 R )-4-methyl-1-(1-methylethenyl)-2-oxocyclohexyl]-4-phenyl-1,2,4-triazolidine-3,5-dione ( SR -isomer). Along with these epimers, we found another isomer - 1-{1-methyl-1-[(4 R )-4methyl-6-oxocyclohex-1-en-1-yl]ethyl}-4-phenyl-1,2,4-triazolidine-3,5-dione. Quantum chemical modeling has established that isomeric products of hydrogen substitution in pulegone by enophil are formed along three routes. In the SR -isomer formation route, the ene reaction proceeds consistently. The other two routes are implemented with the enophil approach from the R -side of the pulegon. These routes consist of two consecutive stages. At the first stage, an intermediate of the type of asymmetric cyclic aziridine cation is formed. Elimination of a proton from one of the geminal methyl groups of the intermediate leads to an RR -isomer with a terminal double bond. When a proton is eliminated from the methylene group of the pulegog ring, an internal unsaturated compound is formed. The ratio of the yield of the isomer with an internal double binding and the RR -isomer depends on the polarity of the aprotic solvents.

Synchronous and Zwitterionic Channels of the Reaction of (R)-5-Methyl-2-(propan-2-ylidene)cyclohexanone with 4-Phenyl-3H-1,2,4-triazole-3,5(4H)-dione

Synchronous and Zwitterionic Channels of the Reaction of (R)-5-Methyl-2-(propan-2-ylidene)cyclohexanone with 4-Phenyl-3H-1,2,4-triazole-3,5(4H)-dione

Toward Verifying Cooperatively Scheduled Runtimes Using CSP

In this article, we present the novel verification of synchronous channel communication and channel alternation (choice) by considering the environment within which our primitives are executing. Our work is in exploring development of a multi-threaded scheduler for a cooperatively scheduled process-oriented language, ProcessJ. We use communicating sequential processes to produce formal specifications for the implementation of the various parts of the language runtime (scheduler, runtime components, and generated code). We use established communicating sequential process specifications that model channel communication and choice as well as the formal verification tool FDR to formally prove that the implementations are correct and behave as expected, when executed by our scheduler (the execution environment). Our approach is novel and not seen in similar research, as we consider the behavior of the systems we examine under the restrictions imposed by an execution environment (a runtime system, a scheduler, an operating system, etc.) and show that even with such restrictions the channel communication and alternation work. More specifically, we show correctness when a system is executed by the ProcessJ cooperative scheduler. The main contributions of this work are in the models defined and method undertaken to verify cooperatively channel communication and choice.

At your service: supportiveness of servant leadership, communication frequency and communication channel fostering job satisfaction across generations.

The present study contributes to the conversations on the role of 'autonomy supportive' factors in employee wellbeing in remote work contexts by examining the relationships between servant leadership, communication frequency - overall and via synchronous (i.e., individual video-calls, individual telephone calls) and asynchronous communication channels (i.e., e-mail messages, and WhatsApp) - on the one hand, and job satisfaction, on the other, and the moderating role of generation (Baby Boomers and Gen X versus Gen Y) in these relationships. Building on self-determination theory, incorporating insights from servant leadership, telework, and media richness and synchronicity literatures, we developed hypotheses that were tested via multilevel analysis (273 employees nested in 89 managers). In line with expectations, servant leadership had a positive relationship with job satisfaction. Total communication frequency, however, was not related to job satisfaction. Further analyses per communication channel showed that only level 2 e-mail communication frequency was positively related to job satisfaction. In contrast to expectations, the relationships studied were not moderated by generation. We concluded that, for all generations, both servant leadership and frequent (e-mail) communication can be regarded as 'autonomy supportive' factors in employee wellbeing. Paradoxically, whereas servant leadership, considered as a human-centric leadership style, suggests close trust-based employment relationships, employees valued frequent asynchronous communication (via e-mail). Having access to information and knowledge when needed may satisfy employees' need for autonomy (and perhaps for flexibility to engage in work and non-work activities). The insights gained in our study can inform organizations, managers, and employees, particularly in future remote work contexts.

Local Correlation Metric for Assessing the Quality of Combined AFM Images

The problem of assessing the quality of combining component images formed in two synchronous channels of an atomic force microscope (AFM images), is considered. A computationally simple quality metric for combining component AFM images, based on local correlation coefficients is proposed, taking into account the contribution of each of the component AFM images to the resulting combined AFM image and the correlation between component AFM images. It is shown that local correlation provides a higher accuracy of AFM images combination quality estimation in comparison to the global correlation.

ОСОБЛИВОСТІ ВИКОРИСТАННЯ АЛГОРИТМІЧНОГО СПОСОБУ РЕЗЕРВУВАННЯ PRC ПРИ МОДЕРНІЗАЦІЇ КОМПЛЕКСУ ПЕРВИННИХ ПРИСТРОЇВ СИНХРОНІЗАЦІЇ

In modern synchronization networks, PRC primary synchronization devices have become an integral component necessary to ensure stable operation and long-term accuracy of reference signals. But their high cost and insufficient use to provide only one unit lead to the need to find other options. Frequency standard manufacturers supply PRS as dedicated hardware without redundancy, whereas in modern synchronization networks PRS must be redundant in order to maintain the required quality of the reference signals. The paper considers the possibilities of modernization of the complex of primary devices of the synchronization network using the example of PJSC “Ukrtelecom” and analyzes the features of using the BesTime algorithm. The main advantages of the protocol in ensuring stable and high-quality operation of the synchronization network are considered. The basic principle of operation of the BesTime algorithm is described, as an algorithmic method of PRC reservation during modernization, the basis of the algorithm is the “triangular hat” method, and as a result, the resulting signal with the best characteristics of one of the three nodes is obtained according to the algorithm. It is demonstrated how the use of the algorithm makes it possible to divide a complex network of synchronization channels into simple and well-controlled fragments with equally high quality reference signals.

ASAA: Multihop and Multiuser Channel Hopping Protocols for Cognitive-Radio-Enabled Internet of Things

The devices of Internet of Things (IoT) are integrated and interconnected by using the traditional wireless communication technology. Unavailability of spectrum sharing occurs in traditional wireless communication due to the presence of a massive number of IoT devices. Thus, Cognitive Radio Network (CRN) is introduced as a promising technology to utilize the spectrum efficiently. Channel Hopping Sequence (CHS) is used to establish communication among CRN users. However, the majority of CHS mechanisms only focus on multi-user single-hop scenarios, which can lead to bottleneck and throughput degradation problems. It is also found that few existing CHS mechanisms still have a low percentage of rendezvous that can cause difficulties for the Secondary Users (SUs) to communicate. Thus, it is a challenge to design efficient CHS for establishing fast communication among SUs under multi-user, multi-hop scenarios and asymmetric asynchronous environments. In this paper, Asymmetric Synchronous and Asymmetric Asynchronous (ASAA) Channel Hopping (CH) algorithms are designed for the multi-user CRN-enabled IoT devices to share the unused spectrum in the multi-hop scenario. The Multi-User Asymmetric Synchronous (MUAS) and Multi-User Asymmetric Asynchronous (MUAA) protocols are designed in the proposed ASAA channel hopping mechanism. The simulation results show that the proposed ASAA CHS algorithms outperform the existing CHS mechanisms in terms of throughput, Channel Loading (CL), Channel Utilization (CU), Maximum Time To Rendezvous (MTTR), Average Time to Rendezvous (ATTR) and Maximum Inter Rendezvous Interval (MIRI).

Socio-technical Constraints and Affordances of Virtual Collaboration - A Study of Four Online Hackathons

Hackathons and similar time-bounded events have become a popular form of collaboration in various domains. They are commonly organized as in-person events during which teams engage in intense collaboration over a short period of time to complete a project that is of interest to them. Most research to date has thus consequently focused on studying how teams collaborate in a co-located setting, pointing towards the advantages of radical co-location. The global pandemic of 2020, however, has led to many hackathons moving online, which challenges our current understanding of how they function. In this paper, we address this gap by presenting findings from a multiple-case study of 10 hackathon teams that participated in 4 hackathon events across two continents. By analyzing the collected data, we found that teams merged synchronous and asynchronous means of communication to maintain a common understanding of work progress as well as to maintain awareness of each other's tasks. Task division was self-assigned based on individual skills or interests, while leaders emerged from different strategies (e.g., participant experience, the responsibility of registering the team in an event). Some of the affordances of in-person hackathons, such as the radical co-location of team members, could be partially reproduced in teams that kept open synchronous communication channels while working (i.e., shared audio territories), in a sort of "radical virtual co-location". However, others, such as interactions with other teams, easy access to mentors, and networking with other participants, decreased. In addition, the technical constraints of the different communication tools and platforms brought technical problems and were overwhelming to participants. Our work contributes to understanding the virtual collaboration of small teams in the context of online hackathons and how technologies and event structures proposed by organizers imply this collaboration.

Mean-Based Trace Reconstruction Over Oblivious Synchronization Channels

Mean-based reconstruction is a fundamental, natural approach to worst-case trace reconstruction over channels with synchronization errors. It is known that <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\exp (\Theta (n^{1/3}))$ </tex-math></inline-formula> traces are necessary and sufficient for mean-based worst-case trace reconstruction over the deletion channel, and this result was also extended to certain channels combining deletions and geometric insertions of uniformly random bits. In this work, we use a simple extension of the original complex-analytic approach to show that these results are examples of a much more general phenomenon. We introduce <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oblivious synchronization channels</i> , which map each input bit to an arbitrarily distributed sequence of replications and insertions of random bits. This general class captures all previously considered synchronization channels. We show that for any oblivious synchronization channel whose output length follows a sub-exponential distribution either mean-based trace reconstruction is impossible or <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\exp (O(n^{1/3}))$ </tex-math></inline-formula> traces suffice for this task.

Multilink Operation in IEEE 802.11be Wireless LANs: Backoff Overflow Problem and Solutions.

The next-generation wireless LAN standard named IEEE 802.11be supports a multilink operation to cost-efficiently boost throughput performance, for which an efficient multilink channel scheme is essential. The synchronous channel access scheme with an enhancement allowing multilink transmission before backoff completion greatly enhances the performance of multilink devices with no simultaneous transmit and receive capability, for which, however, backoff count compensation is necessary for coexistence with legacy and other multilink devices. In this paper, we identify the backoff count overflow problem of the enhanced synchronous channel access scheme with backoff compensation, which becomes aggravated once triggered due to repeated compensations. Then, we propose four solutions to mitigate this problem: limiting consecutive free-riding transmissions, limiting a compensated backoff value, using the contention window value of a main link, and balancing transmissions between links. Through comparative evaluation and analyses for dense single-spot and indoor random deployment scenarios, we demonstrate in terms of throughput and latency that the proposed solutions successfully mitigate the problem while preserving the coexistence performance.

Multi-Link Operation with Enhanced Synchronous Channel Access in IEEE 802.11be Wireless LANs: Coexistence Issue and Solutions.

Multi-link operation is a new feature of IEEE 802.11be Extremely High Throughput (EHT) that enables the utilization of multiple links using individual frequency channels to transmit and receive between EHT devices. This paper aims to illustrate enhanced multi-link channel access schemes, identify the associated coexistence challenge, and propose solutions. First, we describe the multi-link operation of IEEE 802.11be and how the asynchronous and synchronous channel access schemes facilitate multi-link utilization. Next, we describe the design variants of the synchronous channel access scheme and demonstrate the associated coexistence challenge. Subsequently, we propose four features to address this challenge by assigning penalties to multi-link devices (repicking a backoff count, doubling the contention window size, switching to another contention window set, and compensating the backoff count) as well as five coexistence solutions derived from combinations of these features. Comparative simulation results are provided and analyzed for dense single-spot and indoor random deployment scenarios, demonstrating that the throughput and latency gains of multi-link operation differ between schemes. At the same time, we investigate the coexistence performance of multi-link operation with and without the capability of simultaneous transmission and reception and demonstrate that the proposed solutions mitigate the coexistence problem. In particular, compensating the backoff count achieves the highest coexistence performance among the proposed solutions, with a marginal throughput decrease of multi-link devices. A metric for evaluating both the throughput and latency gains and the coexistence performance of a multi-link channel access scheme using a single value is also proposed.

SecRSL: security separation logic for C11 release-acquire concurrency

We present Security Relaxed Separation Logic (SecRSL), a separation logic for proving information-flow security of C11 programs in the Release-Acquire fragment with relaxed accesses. SecRSL is the first security logic that (1) supports weak-memory reasoning about programs in a high-level language; (2) inherits separation logic’s virtues of compositional, local reasoning about (3) expressive security policies like value-dependent classification. SecRSL is also, to our knowledge, the first security logic developed over an axiomatic memory model. Thus we also present the first definitions of information-flow security for an axiomatic weak memory model, against which we prove SecRSL sound. SecRSL ensures that programs satisfy a constant-time security guarantee, while being free of undefined behaviour. We apply SecRSL to implement and verify the functional correctness and constant-time security of a range of concurrency primitives, including a spinlock module, a mixed-sensitivity mutex, and multiple synchronous channel implementations. Empirical performance evaluations of the latter demonstrate SecRSL’s power to support the development of secure and performant concurrent C programs.

Uncertainty quantification in Bayesian operational modal analysis with multiple modes and multiple setups

In full-scale ambient vibration tests, multiple setups are often performed for measurement when it is demanded to obtain a detailed mode shape with more measured degrees of freedom than the available number of synchronous data channels. In a previous work, a Bayesian operational modal analysis framework for the general case of multiple modes identified with ambient data from multiple setups was developed, together with an Expectation-Maximisation algorithm for efficiently calculating the most probable value (MPV) of modal parameters. Complementing the previous effort, this work investigates the posterior uncertainty of the modal parameters in terms of their posterior covariance matrix. Mathematically, the posterior covariance matrix is equal to the inverse of the Hessian of negative log-likelihood function at the MPV. The computational issues are investigated and analytical expressions for the Hessian matrix are derived, allowing the covariance matrix to be determined efficiently and accurately without resorting to the finite difference method. The proposed algorithm is verified with synthetic data, where the Bayesian and frequentist statistics are compared, and the effect of reference location is investigated. The developed computational tools are applied to investigate identification uncertainty with field data, where associated practical issues are also discussed.

Research on the Satisfaction of Hybrid College English Teaching Based on Artificial Intelligence Rain Classroom

With the rapid development of Artificial Intelligence (hereinafter referred to as AI), TRC has become a popular teaching tool. Through the rain classroom (hereinafter referred to as TRC) mixed teaching, we can strengthen the quality and feasibility of College English teaching (hereinafter referred to as CET). TRC is a lightweight intelligent teaching tool, which can build a synchronous dual channel between teachers and students (hereinafter referred to as TAS). Through the rain class, we can analyze the asynchronous teaching of CET, which will achieve high-quality English teaching before, during and after class. Through the construction of hybrid CET mode based on TRC, this paper realizes the English teaching before, during, after class and evaluation. Compared with traditional teaching, this paper analyzes the students’ satisfaction with rain class. Finally, this paper puts forward some suggestions, which can better improve students’ enthusiasm, autonomy and satisfaction.

The impact of media use on the spillover and crossover effect of couple conflict

This 5-day daily diary study examined the influence of media use on the spillover and crossover effect of couple conflict among married and dating couples. Couples aged 18–38 years recorded their daily overload, negative mood, couple conflict, media use, flooding, and satisfaction. The results showed negative spillover and crossover effects: individuals reported more negative moods and couple conflict in response to their own and their partners’ increase in daily overload. Following media synchronicity theory, the more synchronous media couples used in conflict, the more they resolved the conflict. In addition, the more couples segmented their channels, the less they flooded and the more they resolved the conflict. The results suggest that dating and married couples might benefit from managing conflict associated with spillover and crossover effects using synchronous channels that are segmented.