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Controlled depolarization of a polychromatic carrier can be applied simultaneously with polarization-shift keying (PolSK) to achieve a three-dimensional symbol space using only a direct-detection Stokes-vector receiver. I present a scheme to implement such modulation of a two-tone carrier, analyzing the noise statistics of the received degree-of-polarization (DOP) variable to compute the bit-error rate (BER). I then quantify the impact to simultaneous PolSK signaling and determine the optimal DOP that minimizes the overall BER. Finally, I compare the new combined format to conventional multilevel intensity modulation.

WiFi-based passive gesture tracking plays a crucial role in promoting human-computer interface, due to its pervasive availability and cost-effectiveness. Prior works focus on tracking gestures on 2D sensing plane by aggregating multiple WiFi links (typically 2), with Uniform Linear Arrays (ULAs). However, gestures actually contain 3D spatial information instead of just 2D, thus interpreting the 3D traces as 2D may lead to enormous tracking errors. This paper aims at exploring the possibility of passively tracking 3D hand traces likewise leveraging two WiFi links with standard 3-element ULAs, and presents a generic 3D centimeter-level passive gesture tracking system, called CentiTrack-3D. To this end, we make two key observations: (1) The ULA-resolved angle contains the integrated information of the azimuth and elevation in 3D space, despite its inability to estimate azimuth and elevation separately. (2) The radial motion deviating from the sensing plane also leads to length variations of paths. Motivated by the observations, a 3D tracking model named Chaos is elaborately designed to deduce the hand 3D coordinates, so as to track the traces. Extensive experiments yield that CentiTrack-3D achieves an overall median tracking granularity of 2.5 cm in 3D space in case of diverse users and environment conditions.

In the software development process, traceability links between unit tests and code are not explicitly maintained, and dependencies in most cases are manually identified. As a result, a large amount of effort and time is required during the comprehension process to establish the links between these artifacts. Although there are several methods that can infer such links based on different phenomenons, these methods usually produce different set of traceability links. This work expands upon previous traceability link recovery and visualization studies by implementing a combination of traceability recovery methods that automatically retrieve the links, and visualizing them to help developers to overview the links inferred by various recovery techniques, and also to select the right relations for analyses. The results of the usability study show that the visualization model presented herein can effectively support browsing, comprehension, and maintenance of Test-to Code Traceability (TCT) links in a system with enhanced efficiency, as well as visualization of TCT links from multiple sources is better than a visualization of single source of traceability links.

Detector readout systems for medium to large scale physics experiments, and instruments in some other fields as well, are generally composed of multiple front-end digitizer boards distributed over a certain area. Often, this hardware has to be synchronized to a common reference clock with minimal skew and low jitter. Today's mainstream solutions to precise clock distribution and deterministic latency messaging rely on the capabilities of high speed serial transceivers (a.k.a. SerDes) embedded in modern Field Programmable Gate Arrays (FPGAs). An alternative option uses distinct clock and data links. This can potentially reach higher synchronization accuracy, at significant hardware expenses. This work reports some first steps to explore a third scheme for clock and synchronous message distribution. Like the standard approach, the same media is used to convey clock and data, but instead of using today's "data-centric" links where the recovered clock is only a by-product of a SerDes, this paper defines and investigates "clock-centric" links where, at the opposite, a clock is carried by the link, and synchronous data are embedded into it by a modulation technique. After defining the concepts and principles of data-centric links, experimental studies are presented. Finally, the merits and limitations of the proposed approach are discussed., Presented at the virtual IEEE 22nd Real Time Conference, 12-23 October 2020. 11 pages, 20 figures

Background and Aim: Given the conflicting and unreliable evidence for using cross-links in posterior spine surgery, this review was conducted to highlight the different features and usefulness of these augmentation devices in spine surgeries. Methods and Materials/Patients: After searching databases using specific keywords, the relevant articles were ultimately selected and evaluated. Results: Biomechanically investigating the use of cross-links has not resulted in unanimous explanations for their effect. The site and direction of cross-links have been rarely investigated in the literature. Some studies recommended eliminating their application from clinical practice; nevertheless, these studies do not necessarily yield clinical benefits. Posterior spinal fixation with pedicle screws and without cross-links offers stability in all the planes in most clinical conditions. Conclusion: Excluding the cross-links in posterior spine surgery may shorten the operation time and reduce hospital costs. Researchers have reported other problems for cross-links such as late pain, device failure, infections, device prominence, and pseudarthrosis which may be obliterated through the avoidance of their combination in a spinal construct; nevertheless, the results of animal models of the application of special cross-links in a degenerative disorder or deformity suggest that diagonal cross-links provide the highest stability of the construct if they are matched with a rodonly system or with transverse cross-link constructs resulting in a rectangular configuration.

The utilization of drones as flying base stations (BSs) in the sixth-generation (6G) cellular networks has attracted much attention recently. In this context, free-space optical (FSO) systems could be deployed to provide high-capacity fronthaul/backhaul links between drones and ground BSs. Particularly, a drone-to-ground FSO communication link can be established by equipping the drone with a modulating retro-reflector (MRR) to modulate the incoming optical beam and reflect the modulated beam back along the same path. This helps to alleviate stringent pointing requirements from the drone while satisfying the limited size, weight, and power (SWaP) consumption requirements. Nevertheless, the underlying physical channel effects of this aerial retro-reflected FSO system have never been experimentally explored in the literature. In this paper, we report, for the first time, the experimental channel statistics of a drone-to-ground retro-reflected FSO link, offering practical insights into the angle-of-arrival (AoA) fluctuations at the receiver, the channel coherence time, the probability of fade, the level crossing rate, the average fade duration, and the time-frequency channel characteristics. Our results are expected to serve as practical sources of reference for the theoretical performance analyses and engineering designs of drone-based retro-reflected FSO systems.

Terahertz (THz) band spans the frequencies lying between 0.1 and 10 THz and represents the gap between millimeter waves and Infrared bands. THz will play an influential role in mitigating the spectrum resources shortage to meet the exponential growth of services and wireless devices. Standardization activities are being carried out to regulate the THz bands exploitation under the IEEE 802.15 standardization project. Despite the generous bandwidth, THz communications suffer from high pathloss and attenuation due to Molecular Absorption. As such, THz systems need to use extra power, suitable antennas, and enhanced signal processing and communication techniques to compensate for different signal attenuation sources. In this paper, we propose a new operation mode for the IEEE standard 802.15 to save the power transmission requirement while achieving the required data rate. Hence, less battery or antenna size are needed to support the same communication link quality. To this end, we optimize the power, modulation scheme, and channel allocation to minimize the total transmitted power keeping a minimum quality-of-service. Moreover, the design captures the effect of different weather conditions that are we detail their impact on the channel attenuation.

A geographical routing scheme for LEO satellite constellations with intersatellite links is proposed, implemented, and analyzed for two Walker Star constellations. The approach targets reliable transmissions with low latency and high data rates even in scenarios with significant traffic load. An Iridium‐like constellation and a megaconstellation are investigated and compared regarding the address resolution procedures, the average end‐to‐end transmission delay, and the dropping and rerouting rates using a system level simulator.

A high number of research work is being carried out in the field of DC-DC converters to improve the performance of microgrid operation. The DC microgrid has a high level of acceptance because of the integration of renewable energy sources. In DC Microgrid, there is a need for improved DC-DC converter topologies which offer high gain, small size, enhanced efficiency, reduced voltage stress and reduced component count etc. A new Triple-Mode Active-Passive Parallel Intermediate Links (TM-A2P-IL) converter is proposed in the paper. The A2P-IL is designed by a combination of an inductor, capacitor, diode, and control switch. The proposed converter is derived by inserting A2P-IL in conventional boost converter. The proposed TM-A2P-IL converter operates in three modes and provides a high voltage gain without using a transformer, voltage multiplier stages, coupled inductor, switched inductor/capacitor circuitry. The other benefits of the proposed TM-A2P-IL converters are flexibility in the selection of duty cycles, reduced voltage stress of devices, small reactive components, single-stage power conversion. The proposed converter circuit, operating principle, steady-state analysis is studied for both CCM and DCM, discussed. The comparison between available similar type converters and the proposed converter is provided. The operation and performance of the proposed A2P-IL converter are validated through simulation and experimental work.

We explore whether accounting fraud can be detected using the information of firms economically linked to a focal firm. Specifically, we examine whether customer information disclosed by a supplier firm, combined with customers’ accounting information, helps to detect the supplier’s revenue fraud. We first confirm the economic link between the supplier and customers by showing a strong positive correlation between the supplier’s sales growth and the growth rate of total customer purchases. We then introduce two variables based on customer accounting information—the discrepancy between supplier sales growth and customer purchase growth and customer excess purchases—and show that they are predictive of supplier revenue fraud. We conduct a battery of cross-sectional tests and generally find results to vary cross-sectionally in a predictable way. Finally, the out-of-sample tests indicate that adding the two variables to Dechow, Ge, Larson, and Sloan (2011) model increases fraud prediction accuracy. JEL Classifications: G14; M40; M41; M42.

Many link prediction algorithms regarding single-layer social networks have been proposed, and however, how to predict interlayer links in multiplex social networks is still in the initial stage. In fact, the prediction of interlayer links in multiplex networks is of great significance, which is closely related to network security, product recommendation, social network mining, and so forth. Given that many social networks are sparse and the number of the first-order common matched neighbors (CMNs) is very few, it is not sufficient to implement link prediction only based on the first-order CMNs. Moreover, many social networks have scale-free property, leading to the roles of CMNs in link prediction which are significantly different. In doing so, we propose a second-order iterative degree penalty (SOIDP) algorithm to predict interlayer links in multiplex networks, in which the information of the first- and second-order CMNs is integrally considered, as well as a degree penalty mechanism is introduced to give larger weight to the CMNs with fewer connections. In particular, to solve the problem of cumulative error in the iterative process, we demonstrate that the interlayer links can be predicted by directly calculating the matching degree matrix without iteration. Experiments on real-world networks show that the performance of SOIDP algorithm in predicting interlayer links is always better than the baseline algorithms, and the accuracy is increased 10% at least. For synthetic networks, the improvement is also very surprising when networks are rather sparse.

The timber industry is an important intersectoral segment and an element of many production chains. The products of this industry are the raw material base for operation of many units of manufacturing and other economic activities. The purpose of the article is to conduct a comparative assessment of the cross-sectoral links of the Ukrainian timber industry, and to draw relevant analytical conclusions. The main need for assessing the cross-industry relationships of the timber industry is to determine the match and the reciprocal impact of supply and demand on woodworking products. For this purpose, the structure of output and costs (intermediate consumption) of the woodworking industry of Ukraine, Poland, Germany and other EU countries were compared. The information base of the study was the cost-release tables. An empirical study performed by the author reveals that the structure of consumption of timber products with industrial purposes in Ukraine essentially differs from the analogous structure in Poland and Germany by relatively small shares of construction and furniture industry. The revealed structural differences in cross-sectoral links of the timber industry are a core reason explaining why the consumption of timber products by the Ukrainian economy is six times lower than the Polish economy and more than twenty times lower than the German one. As a result, the supply of domestic furniture enterprises and construction sector with input resources is still an empty niche for the domestic timber industry, although a promising one. According to the analysis of the cost structure and dynamics in timber industry of Ukraine, it was found that the cost level of domestic woodworking is the highest among EU countries. This is largely explained by the significant differences in the cost structures (intermediate consumption) of the timber industry of Ukraine and the EU. The latter is dominated by the share of timber products, while in Ukraine it tends to decrease. Also, during 2014–2017, the share of agricultural and forestry products increased in the structure of expenditures of the domestic timber industry, while the share of products and services of retail chains decreased. As a result, there was a decrease in the degree of processing of timber raw materials and deterioration in the manufacturability of production. Hence the need to transform the structure of output in timber industry in a way to increase the output of products for the construction and furniture industries, as well as creating organizational, economic and institutional legal conditions that would contribute to the growth of demand for such products in the domestic and foreign markets.

We investigate the validation of fiber-based optical frequency transfer for frequency comparison applications. We specifically consider the frequency transfer validation for remote optical clock comparisons and want to ensure interferometric fiber link uncertainty contributions below the combined uncertainty of the clocks under test. The validation is based on signals obtained via looping back from the remote end to the sender site and comparing the input with the output of the loop. These loop-back data need to be averaged over intervals for reaching the validation goal, as the short-term instability of long-distance interferometric fiber links is typically higher than that of optical clocks. We introduce a two-step validation approach and address the finding of a compromise between opposing aspects of averaging: reaching low uncertainties versus achieving a high data coverage of the validated data set via a high temporal resolution of the fault identification. We discuss the impact of different averaging types and of the tolerance of filtering criteria on the achievable estimated uncertainty and on the coverage of the validated data set. Data from four multiple-week-long measurement campaigns on the fiber link between Physikalisch-Technische Bundesansanstalt and University of Strasbourg are used for this assessment.

Fibrosis is a pathological state characterized by excessive deposition of the extracellular matrix components leading to impaired tissue function in the affected organ. It results in scarring of the affected tissue akin to an over-healing wound as a consequence of chronic inflammation and repair in response to injury. Persistent trauma of susceptible oral mucosa due to habitual chewing of betel quid resulting in zealous healing of the mucosal tissue is one plausible explanation for the onset of oral submucous fibrosis (OSF). The irreversibility and resistance of collagen to degradation and its high potential to undergo malignant change are a major reason for morbidity in OSF. Hence, early diagnosis and timely treatment are crucial to prevent the progression of OSF to malignancy. This review focuses on the mechanistic insight into the role of collagen cross-links in advancing fibrosis and possible therapeutic targets that bring about a reversal of fibrosis. These options may be beneficial if attempted as a specific therapeutic modality in OSF as is in organ fibrosis. The upregulation of lysyl oxidase and lysyl hydroxylase has been shown to exhibit the higher levels of the hydroxylysine aldehyde-derived cross-links in fibrosis and tumor stroma promoting the tumor cell survival, resistance, and invasion. The in silico analysis highlights the potential drugs that may target the genes regulating collagen crosslinking.

Direct training of selected individuals as disseminating farmers (DFs) can help to implement a farmer to farmer extension approach. This study systematically examines the relationship between social distance and the likelihood of information exchange, subsequently evaluating effects on awareness, knowledge, and adoption of drought-tolerant (DT) varieties of maize, disease-resistant varieties of groundnuts and conservation farming. Using a panel dataset from northern Uganda, the study combines matching techniques with difference-in-difference (DID) approach and employs two-stage least squares regression (2SLS) to identify causal effects. The study finds an increased likelihood of information exchange when the DF is female, regardless of the sex of the neighbour. The likelihood of information exchange increased when distance in farm size cultivated with maize was larger than the median in the sub-village. In terms of non-agricultural assets index, there was an increased likelihood of information exchange both when the distance was smaller and greater than the village median. Information exchange links improved awareness and knowledge for all of the technologies, but only increased adoption of maize varieties. Together, these findings suggest that social distance shapes the diffusion of agricultural knowledge even when DFs are selected by the community to be “representative” and reinforces that social learning can help to address informational constraints to adoption of agricultural technologies.

It is known that data rates in standard cellular networks are limited due to inter-cell interference. An effective solution to this problem is to use the multi-cell cooperation idea. In Cloud Radio Access Network (C-RAN), which is a candidate solution in 5G and future communication networks, cooperation is applied by means of central processors (CPs) connected to simple remote radio heads with finite capacity fronthaul links. In this study, we consider a downlink C-RAN with a wireless fronthaul and aim to minimize total power spent by jointly designing beamformers for fronthaul and access links. We consider the case where perfect channel state information is not available in the CP. We first derive a novel theoretical performance bound for the problem defined. Then we propose four algorithms with different complexities to show the tightness of the bound. The first two algorithms apply successive convex optimizations with semi-definite relaxation ideas where the other two are adapted from well-known beamforming design methods. The detailed simulations under realistic channel conditions show that as the complexity of the algorithm increases, the corresponding performance becomes closer to the bound.

Post-silicon electrical validation of high-speed input/output (HSIO) links is a critical process for product qualification schedules of high-performance computer platforms under current aggressive time-to-market commitments. Improvements in signaling methods, circuits, and process technologies have allowed HSIO data rates to scale well beyond 10 Gb/s. Noise and EM effects can create multiple signal integrity problems, which are aggravated by continuously faster bus technologies. The goal of post-silicon validation for HSIO links is to ensure design robustness of both receiver (Rx) and transmitter circuitry in real system environments. One of the most common ways to evaluate the performance of an HSIO link is to characterize the Rx jitter tolerance (JTOL) performance by measuring the bit error rate (BER) of the link under worst stressing conditions. However, JTOL testing is extremely time-consuming when executed at specification BER considering manufacturing process, voltage, and temperature test coverage. In order to significantly accelerate this process, we propose a novel approach for JTOL testing based on an efficient direct search optimization methodology. Our approach exploits the fast execution of a modified golden section search with a high BER, while overcoming the lack of correlation between different BERs by performing a downward linear search at the actual target BER until no errors are found. Our proposed methodology is validated in a realistic industrial server post-silicon validation platform for three different computer HSIO links: SATA, USB3, and PCIe3.

Wireless communication has become a very important part of our lives, and it is well known that meteorological factors affect the quality of communication links, especially at higher frequencies because the physical dimensions of raindrops, hail stones, and snowflakes are on a similar wavelength to the propagating radio frequency. Millimeter-waves are an important technology for fifth-generation cellular networks which are currently being deployed all over the world. Since atmospheric effects are challenging in millimeter-wave transmissions, in this paper, we conducted line-of-sight field measurements at 25 GHz and 38 GHz. We monitored the received signal during rainfall events and compared the theoretical attenuation and the recorded rain-induced attenuation. We also derived the rain-induced attenuation (A) and rainfall rate (R) relation for stratiform and convective rain, respectively, using local rain drop size distribution (DSD) information at our measurement site collected during the period of two years. Furthermore, opportunistic sensing of atmospheric phenomena using microwave or millimeter-wave communication links in commercial cellular networks has recently attracted more attention in meteorological research worldwide. The accuracy of calculating rainfall rates from microwave links highly depends on the retrieval model and values of coefficients in the model, i.e., a and b of the A-R relation model. Here, the coefficients a and b are estimated based on local DSD measurement, and the performance of the improved A-R model is evaluated using propagated signal power based on measurement data. Compared to the (a, b) coefficients in the International Telecommunication Union Recommendation (ITU-R) P.838 document, the derived coefficients achieved an improved rainfall rate estimation.

There are several ubiquitous kinematic structures that are used in industrial robots, with the most prominent being a six-axis angular structure. However, researchers are experimenting with task-based mechanism synthesis that could provide higher efficiency with custom optimized manipulators. Many studies have focused on finding the most efficient optimization algorithm for task-based robot manipulators. These manipulators, however, are usually optimized from simple modular joints and links, without exploring more elaborate modules. Here, we show that link modules defined by small numbers of parameters have better performance than more complicated ones. We compare four different manipulator link types, namely basic predefined links with fixed dimensions, straight links that can be optimized for different lengths, rounded links, and links with a curvature defined by a Hermite spline. Manipulators are then built from these modules using a genetic algorithm and are optimized for three different tasks. The results demonstrate that manipulators built from simple links not only converge faster, which is expected given the fewer optimized parameters, but also converge on lower cost values. Web of Science 11 6 art. no. 2471

Mobile communication at millimeter-waves (mmWaves) is affected by the rapid and random variations of the wireless environment. This requires accurate channel estimation at the receiver to compensate for the channel dynamics. The required channel training overhead has been shown to occupy a considerable fraction of the mmWave transmission bandwidth, especially when the mobile device (MD) moves at high-speed. We cope with the issue of the rapid variation of the channel by introducing a coherent transmission/detection technique, whose mechanism requires that MD has prior knowledge of its position as an alternative to the channel estimate. In particular, we consider the case of road side links with high-speed MDs and derive a closed-form expression for the optimal detector. We show that the proposed approach reduces the training overhead significantly at the expense of a signal-to-noise ratio (SNR) increase for a given bit error rate.

The problem of distributed synthesis is to automatically generate a distributed algorithm, given a target communication network and a specification of the algorithm's correct behavior. Previous work has focused on static networks with an a priori fixed message size. This approach has two shortcomings: Recent work in distributed computing is shifting towards dynamically changing communication networks rather than static ones, and an important class of distributed algorithms are so-called full-information protocols, where nodes piggy-pack previously received messages onto current messages. In this work, we consider the synthesis problem for a system of two nodes communicating in rounds over a dynamic link whose message size is not bounded. Given a network model, i.e., a set of link directions, in each round of the execution, the adversary choses a link from the network model, restricted only by the specification, and delivers messages according to the current link's directions. Motivated by communication buses with direct acknowledge mechanisms, we further assume that nodes are aware of which messages have been delivered. We show that the synthesis problem is decidable for a network model if and only if it does not contain the empty link that dismisses both nodes' messages., Comment: In Proceedings GandALF 2020, arXiv:2009.09360

Study objectives To examine the longitudinal links between maternal and infant nocturnal wakefulness by employing a trajectory-based approach, and to assess whether the strength of these links differs as a function of sleep assessment method (actigraphy vs. self-report) and sleeping arrangements. Methods Maternal and infant nocturnal wakefulness were assessed with actigraphy and sleep diaries at home for 5 nights, at 3 (N = 191), 6 (N = 178), 12 (N = 155), and 18 (N = 135) months postpartum. Outcome measures included the number of night-wakings (NW) and the length of nocturnal wakefulness (WASO). Results Strong associations between maternal and infant nocturnal wakefulness (controlling for nighttime breastfeeding) were found for NW and WASO. Trajectory analyses demonstrated that the strength of these relations decreased linearly from 3 to 18 months. Furthermore, the findings showed that the links between maternal and infant NW and WASO were stronger for maternal reports than for actigraphy. No consistent differences were found in the strength of the relations between maternal and infant NW and WASO as a function of sleeping arrangements (ie, room-sharing vs. solitary-sleeping families). Conclusions The results suggest that infant and maternal sleep are strongly intertwined, especially during the first 6 months. The decline in the synchronization between maternal and infant nocturnal wakefulness through infant development may be attributed to the growing ability of infants to self-soothe during the night. The findings emphasize the need to study sleep within a family context.

The application of inter-vehicle wireless communi-cation offers significant advantages in terms of improving traffic efficiency and safety while also suffering from unreliable communication links. This paper deals with the problem of event-triggered vehicular platoon control with communication time delay and package dropout, aiming to achieve a suitable trade-off between communication utilization and vehicle following performance. A disturbance based platoon model with communication time delay, package dropout and event-triggered scheme is established. Subsequently, the criterion for co-designing the event-trigger parameters and CACC controller parameters is derived by adopting the parameter space approach with the requirements to ensure individual vehicle internal stability, following accuracy and platoon string stability. To achieve a superior trade-off between communication resource utilization and following performance under unreliable communication condition, the adaptive event-triggered threshold is designed for the varying failure probability. The effectiveness of the proposed adaptive CACC strategy is verified using numerical simulations of a six-vehicle platoon during the FTP 72 drive cycle. The comparison results of three different scenarios show that the adaptive event-triggered scheme guarantees the following performance even when failure probability is 0.4.

Radio-over-fiber (RoF) links successfully provide high data rates and bandwidth capacity with a low complexity system architecture, as compared to its counterpart digital-RoF. In addition, the compound of quadrature amplitude modulation (QAM) and orthogonal frequency division multiplexed (OFDM) modulation schemes further enhance the process of these achievements. However, high data rates and bandwidth-capacity-supported RoF links face nonlinearities (NLs), linear distortions (LDs), and phase noise challenges that degrade the reliability of communication networks (CNs). Therefore, in this paper, to suppress NLs, LDs, and phase noise, next generation cloud radio access networks (CRANs) are investigated using RoF links and wavelength division multiplexing (WDM) methodology based on 16, 32, and 64 QAM-OFDM modulation schemes. The receiver of the proposed framework is designed, applying an improved digital signal processing (DSP) system that includes overlap frequency domain equalization (OFDE), a synchronization process, and time domain equalization (TDE). Theoretical and simulation models are organized for estimating the proposed RoF link with the aid of different values of transmission ranges, input power, output power, bit rate, bits per symbol, channel spacing, and the number of users. The fitness of the model matches that of existing approaches.

Vertical links are dissipative devices in form of beam-column segments that are included in eccentrically braced frames (EBF). Studies related to different configurations of links have been presented for carbon steel elements. Moreover, stainless steel is a nonlinear metallic material with particular appeal for its structural use due to a considerable amount of capabilities such as corrosion, circular life-cycle, strength, ductility and aesthetics. Despite the increase on the use of stainless steel for structural elements in construction, the behavior of this material for structural purposes is not described as carbon steel in all applications. The elastic stiffness, maximum load, shear deformation capacity as well as the energy dissipation in long links are generally affected by the defined geometrical parameters. Due to the material nonlinearity, this influence may be affected considerably. In this paper, a numerical model aimed at depicting the cyclic behavior of vertical short and long links subjected to seismic lateral loads is presented. The model accounts for the material nonlinearity, the geometrical nonlinearity and the detailed definition of boundary conditions from the link connection to the EBF. This research was developed in the frame of the Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad estructural a acciones accidentales de sismo y fuego”, funded by MINECO (Spain).

This paper presents an implementation of structural optimization algorithms for the design of horizontal links of Eccentrically Braced Frames (EBFs) when subjected to monotonic shear loading. The objective is to study optimized geometries that open new design paths for these types of elements. With the advent of new additive manufacturing techniques such as WAAM (wire and arc additive manufacturing), energy dissipators may become one of the strategic applications for 3D printing of steel structures. For this purpose, an optimization procedure based on a displacement-controlled lateral load (push-over) applied to a single-storey EBF has been created using Abaqus FEA and Abaqus Optimization Module (ATOM). The performance of the optimized links has been compared with the performance of original links in terms of initial stiffness, yield strength, maximum strength and energy dissipation. The results show a set of promising geometrical configurations for horizontal links. Further research lines related to cyclic loading, anisotropic behaviour and advanced loading protocols are suggested.

Two modes of failure are analysed for coupling links, the mechanical connections that transmit traction forces between vehicles along the length of a train. Coupling links are designed to withstand the dynamic loads in normal operation but may break if applied loads exceed safe operating limits. Fractography of two failed links revealed that one had failed through brittle fracture, and one through ductile fracture. Metallography indicated that one sample was hardened and tempered with typical tempered martensite microstructure and the other was normalized with a ferrite-pearlite microstructure. A numerical model of a coupling link is developed and validated against experimental data. Results indicate that the failed links experienced loads above the permitted limit.

The COVID-19 crisis brought numerous challenges to work life. One of the most notable may be the acceleration of digital transformation, accompanied by an intensification of e-mail usage and related demands such as high e-mail workload. While research quickly started to examine the implications of these changes for employees, another important group of stakeholders has been overlooked: leaders. We focus on leaders during the COVID-19 crisis and examine how COVID-19 related work intensification links to leaders? e-mail overload appraisal and finally exhaustion and transformational leadership, a leader behavior especially needed in times of crisis. In a five-day diary study in September 2020, 84 leaders responded to daily surveys on 343 days. Results of multilevel analysis showed that perceived COVID-19 related work intensification was positively linked to worktime spent dealing with e-mail and appraised e-mail overload. E-mail overload appraisal was positively related to leaders? exhaustion, but unrelated to their transformational behavior. Day-specific time spent dealing with e-mail, however, was negatively related to transformational leadership. E-mail overload appraisal mediated the relationship between COVID-19 related work intensification and exhaustion. Turning the focus on leaders during the COVID-19 crisis, our study has important implications for the design of work of leaders in times of crisis and beyond.

Small satellites have shorter development cycles and lower costs than the traditional satellites in low-earth orbits (LEOs) and geostationary orbits (GEOs). These advantages and the ultra-wide spectrum availability in the Terahertz (THz) band enable profound potentials for inter-satellite links (ISLs) to achieve ultra-high throughput in both near-Earth and deep-space orbits. In this paper, the ISL channels at THz band are characterized and their link capacity is analyzed. First, the propagation channel effects in both Earth’s upper atmosphere and deep space are investigated to demonstrate the feasibility of THz band for ISLs. Second, an orbital perturbation model for satellite formation flying is proposed and analyzed with actual ephemeris information. Finally, a channel model is developed to investigate the diversity in both polarization and frequency domain for THz band inter-small-satellite communications. Our numerical results demonstrate that 1) the ionospheric plasma does not affect the THz band signal propagation in near-Earth orbits, 2) the beam misalignment loss can be characterized by orbital perturbation factors, and 3) the ISLs in THz band can utilize the diversity techniques to achieve high throughput in both near-Earth and deep-space links.

Recently, Low Earth orbit (LEO) satellite-based systems have attracted tremendous attention and various technologies have been developed for payload miniaturization and optical communications. In addition, mega constellation architectures are expected to be deployed with LEO satellites for global broadband networks. In this paper, we present a thorough analysis of mega constellation architecture in terms of a change in the number of visible satellites and antenna steering capability to investigate the impact of increase in the constellation size and adoption of optical inter-satellite links (ISLs). The network architecture is evaluated with respect to satellite antenna steering capability and the satellite visibility considering the very narrow beam divergence of optical communications. We analyze the impact of a change in relative positions among the satellites due to continuous satellite movement in the constellation. The results offer guidelines for designing a novel visibility matrix using a time-varying satellite topology. This could defuse the problem of conventional studies using fixed visibility matrices. The proposed time-varying visibility matrix achieves better performance than previous pre-assigned links in terms of end-to-end link distance and hop count of LEO satellite networks.

[EN] Throughout the pages of this document, I present the results of the research that was carried out in the context of my PhD studies. During the aforementioned research, I studied the process of Traceability Links Recovery between natural language requirements and industrial software models. More precisely, due to their popularity and extensive usage, I studied the process of Traceability Links Recovery between natural language requirements and Business Process Models, also known as BPMN models. In order to carry out the research, I focused my work on two main objectives: (1) the development of the Traceability Links Recovery techniques between natural language requirements and BPMN models, and (2) the validation and analysis of the results obtained by the developed techniques in industrial domain case studies. The results of the research have been redacted and published in forums, conferences, and journals specialized in the topics and context of the research. This thesis document introduces the topics, context, and objectives of the research, presents the academic publications that have been published as a result of the work, and then discusses the outcomes of the investigation., [ES] A través de las páginas de este documento, presento los resultados de la investigación realizada en el contexto de mis estudios de doctorado. Durante la investigación, he estudiado el proceso de Recuperación de Enlaces de Trazabilidad entre requisitos especificados en lenguaje natural y modelos de software industriales. Más concretamente, debido a su popularidad y uso extensivo, he estudiado el proceso de Recuperación de Enlaces de Trazabilidad entre requisitos especificados en lenguaje natural y Modelos de Procesos de Negocio, también conocidos como modelos BPMN. Para llevar a cabo esta investigación, mi trabajo se ha centrado en dos objetivos principales: (1) desarrollo de técnicas de Recuperación de Enlaces de Trazabilidad entre requisitos especificados en lenguaje natural y modelos BPMN, y (2) validación y análisis de los resultados obtenidos por las técnicas desarrolladas en casos de estudio de dominios industriales. Los resultados de la investigación han sido redactados y publicados en foros, conferencias y revistas especializadas en los temas y contexto de la investigación. Esta tesis introduce los temas, contexto y objetivos de la investigación, presenta las publicaciones académicas que han sido publicadas como resultado del trabajo, y expone los resultados de la investigación., [CA] A través de les pàgines d'aquest document, presente els resultats de la investigació realitzada en el context dels meus estudis de doctorat. Durant la investigació, he estudiat el procés de Recuperació d'Enllaços de Traçabilitat entre requisits especificats en llenguatge natural i models de programari industrials. Més concretament, a causa de la seua popularitat i ús extensiu, he estudiat el procés de Recuperació d'Enllaços de Traçabilitat entre requisits especificats en llenguatge natural i Models de Processos de Negoci, també coneguts com a models BPMN. Per a dur a terme aquesta investigació, el meu treball s'ha centrat en dos objectius principals: (1) desenvolupament de tècniques de Recuperació d'Enllaços de Traçabilitat entre requisits especificats en llenguatge natural i models BPMN, i (2) validació i anàlisi dels resultats obtinguts per les tècniques desenvolupades en casos d'estudi de dominis industrials. Els resultats de la investigació han sigut redactats i publicats en fòrums, conferències i revistes especialitzades en els temes i context de la investigació. Aquesta tesi introdueix els temes, context i objectius de la investigació, presenta les publicacions acadèmiques que han sigut publicades com a resultat del treball, i exposa els resultats de la investigació.

Structural balance theory affirms that in signed social networks with simultaneous friendly/hostile interactions, there is a general tendency of evolving to reduce the tensions. From this perspective, individuals iteratively invert their sentiments to reduce the felt tensions induced by imbalance. Each agent in a signed network has a mixture of positive and negative links representing friendly or antagonistic interactions and his stubbornness about interactions. We define stubbornness as an extreme antagonistic interaction that is resistant to change. In the current paper, we investigate if the presence of stubborn links renders an impact on the balanced state of the network and whether or not the degree of balance in a signed network depends on the location of stubborn links. Our results show that a poorly balanced configuration consists of multiple antagonistic groups. Both analytical and simulation results demonstrate that the global level of balance of the network is more influenced by the locations of stubborn links in the resulting network topology than by the fraction of stubborn links. This means that even with a large fraction of stubborn links the network would evolve towards a balanced state. On the other hand, if a small fraction of stubborn links are clustered in five stubborn communities, the network evolves into an unbalanced state., GRJ and SS gratefully acknowledge support from Cognitive Science and Technologies Council, Iran grant No. 2694.

Subject of Research. One of the ways of automatic text analysis is the construction of subordination trees, in which the words of a sentence are connected with each other by semantic-syntactic links. The field of research is Russian-language texts, which have a general political, artistic and highly specialized character. Special attention is paid to the cases when the words are connected being far from each other at a considerable distance. Method. The subordination trees were built with the help of semantic-syntactical parser.Then the calculation of the distribution of links of different types by lengths was performed. The appearance frequencies of nonlocal links are studied. Main Results. It is shown that the fraction of non-local connections depending on the type can reach up to tens of percent. This is especially important for links coming from predicate nodes (subject, adverbial, etc.), as well as for anaphoric ones. It is noted that publicly available semantic classifiers and thesaurus have limited applicability for solving the problem of correct linking of remoted words in a sentence. Practical Relevance. It is shown that when solving the problem of extracting information that is ontological or scenario-based, as well as coreference, the long syntactic links that form the non-local semantic context cannot be neglected. The conclusion is drawn that the analysis of n-grams only is insufficient for the adequate selection of information from the text that is ontological or scenario. In this regard, there is a need to compile micro-dictionaries, focused on certain syntactic structures

This paper investigates through nonlinear static and dynamic analyses the behaviour of a newly introduced steel and concrete hybrid coupled wall (HCW) system made by a single reinforced concrete (RC) wall coupled to steel columns by means of steel links, a structural solution of potential interest for seismic-resistant multi-storey buildings. The considered HCW is conceived as seismic resistant system where the RC wall and the steel columns remain undamaged while the seismic energy is dissipated by yielding concentrated in the steel links only. In order to achieve such a desired seismic behaviour, a proper design procedure must be adopted and validated. Accordingly, this study reviews a recently proposed design approach and presents some modifications to further improve the seismic behaviour of the considered HCW system. Case studies are designed using the proposed modified design method as well as its former version. Afterwards, the seismic behaviour of the considered case studies is analysed to identify the optimal degree of coupling between the RC wall and steel columns, also evaluating the influence of the building height and uniform or non-uniform distribution of shear links. The obtained results confirm the improvements of the modified design method proposed in this study and provide support for the selection of the design parameter that influences the most in the seismic behaviour of the innovative HCW system, i.e. the degree of coupling between RC wall and steel columns, controlled by the adopted steel links.

Proceedings of SPIE, 11852, ISSN:0277-786X, International Conference on Space Optics — ICSO 2020

Free space optical (FSO) communication is a fast and reliable technology that can be exploited along the radio frequency (RF) wireless channels to enhance the reliability of the networks without generating interference. Efficient wireless communication protocols can be designed by employing data buffers at the relaying stations. In this work, we propose a novel buffer-aided relaying scheme in which the FSO inter-relay links are employed to improve the selection diversity and the RF links are used to deliver packets from the source to the destination. The theoretical outage probability of the network under the proposed protocol is derived and compared with the well-known maximum link relay selection (MLRS) technique as the benchmark. Monte-Carlo simulations demonstrate that the proposed policy outperforms the MLRS technique and the presented theoretical analysis is correct.

In this work, we analyze the effects of the presence of waveguides in a wireless on-chip optical channel, which act as obstacles for the rays composing the propagating signal. The analysis has been performed numerically by using the FDTD method, and the simulation results have been validated by the experimental characterization. This work focuses on the relationship between the received signal and the position of the obstacles on the circuit plane in a multilayered channel made of heterogeneous dielectric cladding. We show how the crossing waveguide perturbates the received power and we provide ad hoc guidelines for the best topological choices allowing to mitigate losses. Moreover, with a good agreement between numerical and experimental results, amounting to a variation of less than 1 dB, we have demonstrated that the effects of this perturbation in real chips can be predicted. The results of this analysis, as well as increasing the level of knowledge of on-chip optical wireless links, allow a better comprehension and control of unbound optical signals within the optical chip environment.

Global rates of obesity and type 2 diabetes mellitus (T2DM) are increasing globally concomitant with a rising prevalence of sleep deprivation and sleep disorders. Understanding the links between sleep, obesity and T2DM might offer an opportunity to develop better prevention and treatment strategies for these epidemics. Experimental studies have shown that sleep restriction is associated with changes in energy homeostasis, insulin resistance and β-cell function. Epidemiological cohort studies established short sleep duration as a risk factor for developing obesity and T2DM. In addition, small studies suggested that short sleep duration was associated with less weight loss following lifestyle interventions or bariatric surgery. In this article, we review the epidemiological evidence linking sleep duration to obesity and T2DM and plausible mechanisms. In addition, we review the impact of changes in sleep duration on obesity and T2DM.

This article presents a class of on-chip links that reduce energy at graceful signal quality degradation via low-swing tuning, leveraging the error resilience of prominent applications (e.g., machine learning, vision). To mitigate the exponential quality degradation at low swings, sub-word ranking and non-uniform swing allocation are introduced. An efficient swing selection to exploit local variations is presented. The proposed links also outperform approximate links in terms of energy and its variability at ISO-quality, while allowing full-quality execution when needed. The proposed techniques are demonstrated in a 28-nm testchip with differential and voltage-scaled standard CMOS links. Results on 20 dies and 3200 links under neural network (LeNet-5 and AlexNet) and computer vision workloads show that the energy can be reduced by up to 5.1X on average across 20 dies, compared with a conventionally designed link. When reusing conventional transmitter and receiver for easy integration, the minimum energy is comparable with prior best-in-class links using more advanced CMOS technologies and dedicated circuit techniques.

In this paper, an improved optimization algorithm is proposed to overcome the original Rao algorithm limitations (i.e., different characteristics in exploration and exploitation) and enhance the performance of the original Rao algorithm. In the improved algorithm, the self-adaptive multi-population and Levy flight methods are utilized in the original Rao algorithm. The improved algorithm is called I_Rao_3. The improved algorithm’s efficiency is confirmed by comparing it to the original Rao algorithm utilizing various standard benchmark test functions. Moreover, the proposed I_Rao_3 algorithm is utilized to improve the frequency response in a hybrid renewable power grid by fine-tuning the proportional-integral-derivative (PID) controller parameters. The targeted system used for this study is a hybrid power grid, which encompasses conventional generating stations (i.e., thermal power plants), renewable power stations (i.e., PV and wind power stations) for the analysis of the load frequency control (LFC) issue. Unlike other previously published works, this study considers the impact of DC links in parallel to AC links to interconnect the two-hybrid renewable power system area. In addition, the nonlinearities effects (i.e., generation rate constraint and a governor dead band) are applied to each area in order to achieve a more realistic study. The superiority of the proposed PID controller-based I_Rao_3 algorithm is endorsed by comparing its performance with many other optimization algorithms.

The reinforced concrete columns and steel beams (RCS) composite frames have received popularity in low to moderate seismic regions due to advantages of the system. However, the poor repairable capacity and deteriorating pinched hysteretic behaviour of the traditional RCS framed structure limit the application in practice under earthquakes. This study presents a modified RCS framed structure with replaceable members aiming to enhance the energy dissipation and resilience capability. The structural configuration character and the general predetermined levels of lateral response of the proposed RCS framed structure with replaceable members is first introduced. Seven quasi-static loading tests were subsequently conducted to evaluate the seismic behavior and replaceability of the replaceable shear links. Parameters including the link length ratio, stiffener configuration and link-to-column connection were examined. The test results depicted that the specimens exhibited the shear dominated behavior. The major failure features of the shear links included web-to-stiffener weld tear, web buckling and web fracture. All tested specimen showed a stable bearing strength, large inelastic rotation capacity and excellent energy dissipation behavior. The same link length ratio of the specimens with different specialized connections presented the similar behavior. Noted that end plate and web stiffeners connection can alleviate the stress concentration on the fillet weld of the flange-to-end plate weld and optimize the performance of the shear link. The average overstrength factor and inelastic rotation capacity of the test specimens were 1.9 and 0.087 rad significantly exceeding 1.5 and 0.08 rad provided by the AISC 341-16 provisions for the EBF links, respectively. In addition, the replaceability of the specimens was evaluated underwent the entire loading process. Compared with the T-shaped and Π-shaped plate connections, replacement of the shear link with the end plate demanded the least effort and time.

Developments made in the fifth generation (5G) and the cellular networks have greatly influenced the lifestyle of the wireless users. Increased demand on higher data rates has also increased the network traffic. In the viewpoint of cellular networks, several Small Cells (SCs) are combined together with the help of microwave communications and millimeter wave communication models, in order to support the heterogeneous environments. In this paper, we have proposed a hybrid communication framework which can efficiently support the interference management, routings in backhaul links and the joint issue during on/off status of the mobile using 5G mmWave backhaul links. A novel cache-enabled technology is designed to develop backhaul links using heuristic search models. Along with that, an effective data access framework is also formulated using distance based cluster head selection that resolves the interference issues. Without modifying the content of the mobile users, the services are offered to the uses associated with backhaul links. Since a fast iterative model is developed, the throughput rate and the energy savings are maximized. A simulation analysis is carried out with a static number of mobile nodes which has proved the efficiency of the proposed framework.

The authors used the proposed method of mathematical and statistical processing of laboratory data (indicators of electrolyte metabolism and osteomarkers) of archived data of 82 patients with various bone diseases aged 9.90 ± 0.55 years compared the structural changes in the panel of ratios of individual electrolytes and the influence of individual indicators on them in personalized data, on the basis of which a conclusion was made about a single mechanism of coinciding influences in the exchange of bone tissue. At the same time, it was found that the complex of associated links detected by the vitamin influence on the panel of electrolyte ratios may differ signifcantly in some cases from each other. These differences consisted in highly pronounced differences in the activity of vitamin D in relation to various components of osteosynthesis and osteolysis, which are described in the modern literature. On this basis, the authors conclude that the used method (analytical system) allows to identify the functional connections of the dynamics of the indicator of vitamin D in individual cases with the dynamics of other indicators of bone, which signifcantly expands the informativeness of the results of laboratory examination of the patient in determining the leading systems the implementation of functional activity of the vitamin. The presented results justify the possibility of creating and describing different images of vitamin D-related changes in the plasma electrolyte composition, followed by their use in the identifcation of certain disorders of calcium metabolism and/or evaluating the effectiveness of the therapy used in each individual case.

The numerical modelling of the torsion behaviour of masonry block interfaces is a key aspect for the assessment of the out-of-plane response of masonry walls. Nevertheless, it still represents a challenging computational issue due to the high non-linear coupling between the torsion and other internal forces (shear, bending moment and axial load), which rigorously requires the adoption of complex 3D non-linear constitutive laws. Some limit analysis-based approaches, proposed in the specific literature, represent efficient and reliable numerical tools for predicting the ultimate states of brick masonry structures subjected to combined in-plane and out-of-plane actions, while involving complex torsion loads and combined actions. This paper originally introduces a simplified discrete inelastic interface able to simulate the non-linear torsion-shear behaviour of masonry contact joints, within the context of static incremental analysis. The more general mechanical behaviour of the interface is ruled by six degrees of freedom and is governed by four rotating links (RL), whose actual orientation is updated during the step by step analysis, by taking into account the current position of the twisting centre of the interface. The incremental torsion-shear capacity curve and the corresponding ultimate domains obtained by the proposed model are compared with the ultimate load limit analysis predictions and with some experimental data available in the literature. The results highlight the ability of the new discrete interface to effectively reproduce the full non-linear behaviour of masonry contact interface subjected to different loading combinations.

The multimode characteristics of vertical cavity surface emitting laser (VCSEL) sources lead to mode partition noise (MPN) impairing high-speed multimode fiber (MMF) links. In this letter, we propose a low-cost and straightforward MPN mitigation scheme by optimizing the launch condition between the VCSEL and the MMF. The dependence of the MPN on launch conditions is theoretically assessed. Simulation shows that the mode power redistribution induced by rearranging the launch condition has great potential to reduce the MPN. Experiments are carried out to demonstrate the MPN reduction. In our case, using a 15- $\mu \text{m}$ radial offset between the VCSEL and the MMF, we observe efficient noise suppression in both the frequency domain and the time domain.

5G systems and networks are expected to provide unprecedented data-rate to final users and services, in combination with increased coverage and density. The traffic generated at the edges of the network should be hauled through high capacity data-conveyors. Extremely high data-rate links able to provide optical-fiber like performance in the order of 100 Gbps are required to reduce the cost and increase the flexibility of the network infrastructure deployment. This paper presents a full transceiver architecture based on a channel-bonding radio-frequency front-end operating at millimeter-wave frequencies and digital baseband processing units able to provide such data-rates with a feasible implementation in low-cost CMOS technologies. The baseband section of the receiver includes digital compensation algorithms that allow to cope with some of the radio front-end impairments. The main functionalities of the proposed transceiver architecture are validated in hardware.

We investigate the Ergodic capacity (EC) performance of device-to-device (D2D) Internet of Things (IoT) relay non-orthogonal multiple access (NOMA)- simultaneous wireless information and power transfer (SWIPT) systems where the relayed communication is supported with direct link. A two-user case is considered in which a base station transmits symbols to two NOMA users, and the energy harvesting (EH) based relay node via a direct link. The EH based relay node harvests the energy from the BS's signal and again transmits a superimposed composite NOMA signal intended for the user with poor channel condition and for its D2D user to offload its data traffic. A D2D user offloading is considered to further enhance the spectral efficiency of the system. We derive the analytical expressions for the EC of each of the user and the ergodic sum capacity (ESC) of the system and validate them with simulation results. In such settings, our results demonstrate that the EC of a node and the ESC of the system can be improved through the maximal ratio combining (MRC) scheme compared to a system with single signal decoding scheme. Our results also indicate that the overall ESC of the NOMA-SWIPT system can be improved by having a direct link for a user in the system.

A split dc-link dual-active-bridge (SDLDAB)-based multiport converter (MPC) is proposed in this article. The intended application of the SDLDAB converter is to interface two solar photovoltaic (PV) modules and a battery bank with a dc microgrid. Depending upon the prevailing atmospheric condition, these two solar PV modules can be operated at their maximum power points. This is achieved by maintaining appropriate voltages at the input terminals of the two PV modules. A high-frequency transformer is employed to provide high voltage gain between the dc microgrid and PV as well as battery ports. A direct power flow path is established between the solar PV modules and the battery without involving the transformer. The transformer current is minimized by appropriately modulating the switching sequence of the SDLDAB. Detailed simulation studies are carried out to predict the performance of the system. A laboratory prototype of the SDLDAB having 1-kW power rating is fabricated. The performance of the MPC is validated by carrying out detailed experimental studies on the developed prototype.