Traditionally, the frequency spectrum is licensed to users by government agencies in a rigid manner where the licensee has the exclusive right to access the allocated band. Therefore, licensees are ...protected from any interference all the time. From a practical standpoint, however, an unlicensed (secondary) user may share a frequency band with its licensed (primary) owner as long as the interference it incurs is not deemed harmful by the licensee. In a fading environment, a secondary user may take advantage of this fact by opportunistically transmitting with high power when its signal, as received by the licensed receiver, is deeply faded. In this paper we investigate the capacity gains offered by this dynamic spectrum sharing approach when channels vary due to fading. In particular, we quantify the relation between the secondary channel capacity and the interference inflicted on the primary user. We further evaluate and compare the capacity under different fading distributions. Interestingly, our results indicate a significant gain in spectrum access in fading environments compared to the deterministic case
The use of low-cost sensor technology to monitor air pollution has made remarkable strides in the last decade. The development of low-cost devices to monitor air quality in indoor environments can be ...used to understand the behaviour of indoor air pollutants and potentially impact on the reduction of related health impacts. These user-friendly devices are portable, require low-maintenance, and can enable near real-time, continuous monitoring. They can also contribute to citizen science projects and community-driven science. However, low-cost sensors have often been associated with design compromises that hamper data reliability. Moreover, with the rapidly increasing number of studies, projects, and grey literature based on low-cost sensors, information got scattered. Intending to identify and review scientifically validated literature on this topic, this study critically summarizes the recent research pertinent to the development of indoor air quality monitoring devices using low-cost sensors. The method employed for this review was a thorough search of three scientific databases, namely: ScienceDirect, IEEE, and Scopus. A total of 891 titles published since 2012 were found and scanned for relevance. Finally, 41 research articles consisting of 35 unique device development projects were reviewed with a particular emphasis on device development: calibration and performance of sensors, the processor used, data storage and communication, and the availability of real-time remote access of sensor data. The most prominent finding of the study showed a lack of studies consisting of sensor performance as only 16 out of 35 projects performed calibration/validation of sensors. An even fewer number of studies conducted these tests with a reference instrument. Hence, a need for more studies with calibration, credible validation, and standardization of sensor performance and assessment is recommended for subsequent research.
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•Low-cost sensor technology major challenge is the lack of data reliability.•Calibration and validation methods varied significantly with each project.•The reported validation results also lacked uniformity.•Studies on long-term stability and cross-sensitivity of the sensors are lacking.•High performance indexes advocate low-cost devices as the (near) future technology.
The 3rd Generation Partnership Project (3GPP) submitted the 5G New Radio (NR) system specifications to International Telecommunication Union (ITU) as a candidate fifth generation (5G) mobile ...communication system (formally denoted as IMT-2020 systems). As part of the submission, 3GPP provided a self-evaluation for the compliance of 5G NR systems with the ITU defined IMT-2020 performance requirements. This paper considers the defined 5G use case families, Ultra Reliable Low-Latency Communication (URLLC), massive Machine Type Communication (mMTC) and enhanced Mobile Broadband (eMBB), and provides an independent evaluation of the compliance of the 3GPP 5G NR selfevaluation simulations with the IMT-2020 performance requirements for connection density, reliability, and spectral efficiency for future mobile broadband and emerging IoT applications. Independent evaluation indeed shows the compliance of the 3GPP 5G NR system with the ITU IMT-2020 performance requirements for all parameters evaluated by simulations.
Aims. We present a new upgraded version of ARES. The new version includes a series of interesting new features such as automatic radial velocity correction, a fully automatic continuum determination, ...and an estimation of the errors for the equivalent widths. Methods. The automatic correction of the radial velocity is achieved with a simple cross-correlation function, and the automatic continuum determination, as well as the estimation of the errors, relies on a new approach to evaluating the spectral noise at the continuum level. Results. ARES v2 is totally compatible with its predecessor. We show that the fully automatic continuum determination is consistent with the previous methods applied for this task. It also presents a significant improvement on its performance thanks to the implementation of a parallel computation using the OpenMP library.
Vehicle Trajectory Similarity Sousa, Roniel S. De; Boukerche, Azzedine; Loureiro, Antonio A. F.
ACM computing surveys,
09/2021, Letnik:
53, Številka:
5
Journal Article
Recenzirano
The increasing availability of vehicular trajectory data is at the core of smart mobility solutions. Such data offer us unprecedented information for the development of trajectory data mining-based ...applications. An essential task of trajectory analysis is the employment of efficient and accurate methods to compare trajectories. This work presents a systematic survey of vehicular trajectory similarity measures and provides a panorama of the research field. First, we show an overview of vehicle trajectory data, including the models and some preprocessing techniques. Then, we give a comprehensive review of methods to compare trajectories and their intrinsic properties. We classify the methods according to the trajectory representation and features such as metricity, computational complexity, and robustness to noise and local time shift. Last, we discuss the applications of vehicular trajectory similarity measures and some open research problems.
•Effect of aging on the mechanical properties of wood and timber.•Aging is a complex phenomenon including load history and chemical composition change.•Contrasting results reported due to the ...difficulty to test old wood/timber.•Majority of works agree on the fact that MOR and MOE are slightly affected by aging.•Needs to standardize tests on old wood/timber to allow a reliable comparison process.
The effect of time on the mechanical properties of wood is of interest for structural engineers, wood technologists and conservators; for the old timber structure assessment, for the potential reuse of salvaged timbers and poles and for the conservation of wooden artefacts as well. The topic was investigated since the 50’s, but the results reported in literature are not always concordant. This is a consequence of the fact that this kind of research works are quite difficult, as a consequence of the material characteristics itself: mechanical properties variability, low availability of material, uncertainty about the “history” of the tested material, unknown original mechanical properties. Another source of uncertainty between the research works is a consequence of the different research approaches: some have investigated only the effect of the time passing (therefore, aging), others consider the aging effect together with other effects, like the state of conservation and the duration of load. The main interest of the researchers was in the bending properties variation, while for other mechanical properties less information is available. In this paper, the results of several research works are presented and analysed regarding the differences in the mechanical properties for elements with different age levels. Moreover, recommendations for future research are included attending to the conclusions drawn from the analysed literature.
Several studies tried to estimate atmospheric emissions with origin in the maritime sector, concluding that it contributed to the global anthropogenic emissions through the emission of pollutants ...that have a strong impact on hu' health and also on climate change. Thus, this paper aimed to review published studies since 2010 that used activity-based methodology to estimate ship emissions, to provide a summary of the available input data. After exclusions, 26 articles were analysed and the main information were scanned and registered, namely technical information about ships, ships activity and movement information, engines, fuels, load and emission factors. The larger part of studies calculating in-port ship emissions concluded that the majority was emitted during hotelling and most of the authors allocating emissions by ship type concluded that containerships were the main pollutant emitters. To obtain technical information about ships the combined use of data from Lloyd's Register of Shipping database with other sources such as port authority's databases, engine manufactures and ship-owners seemed the best approach. The use of AIS data has been growing in recent years and seems to be the best method to report activities and movements of ships. To predict ship powers the Hollenbach (1998) method which estimates propelling power as a function of instantaneous speed based on total resistance and use of load balancing schemes for multi-engine installations seemed to be the best practices for more accurate ship emission estimations. For emission factors improvement, new on-board measurement campaigns or studies should be undertaken. Regardless of the effort that has been performed in the last years to obtain more accurate shipping emission inventories, more precise input data (technical information about ships, engines, load and emission factors) should be obtained to improve the methodology to develop global and universally accepted emission inventories for an effective environmental policy plan.
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•Global exhaust ship emissions have increased considerably over the past decades.•Strong efforts have been made to improve the calculation of ship emissions.•An effective political strategy is needed to control atmospheric ship emissions.•The use of the activity-based method to assess ship emissions is highly encouraged.•Different data sources should be combined for more comprehensive/accurate results.
Available studies on ship emissions should adopt a universally accepted methodology using the activity-based approach.
Advancements in modern medicine have bolstered the usage of home-based rehabilitation services for patients, particularly those recovering from diseases or conditions that necessitate a structured ...rehabilitation process. Understanding the technological factors that can influence the efficacy of home-based rehabilitation is crucial for optimizing patient outcomes. As technologies continue to evolve rapidly, it is imperative to document the current state of the art and elucidate the key features of the hardware and software employed in these rehabilitation systems. This narrative review aims to provide a summary of the modern technological trends and advancements in home-based shoulder rehabilitation scenarios. It specifically focuses on wearable devices, robots, exoskeletons, machine learning, virtual and augmented reality, and serious games. Through an in-depth analysis of existing literature and research, this review presents the state of the art in home-based rehabilitation systems, highlighting their strengths and limitations. Furthermore, this review proposes hypotheses and potential directions for future upgrades and enhancements in these technologies. By exploring the integration of these technologies into home-based rehabilitation, this review aims to shed light on the current landscape and offer insights into the future possibilities for improving patient outcomes and optimizing the effectiveness of home-based rehabilitation programs.
The viscoelastic properties of human kidney cell lines from different tumor types (carcinoma (A-498) and adenocarcinoma (ACHN)) are compared to a non-tumorigenic cell line (RC-124). Our methodology ...is based on the mapping of viscoelastic properties (elasticity modulus E and apparent viscosity η) over the surface of tens of individual cells with atomic force microscopy (AFM). The viscoelastic properties are averaged over datasets as large as 15000 data points per cell line. We also propose a model to estimate the apparent viscosity of soft materials using the hysteresis observed in conventional AFM deflection-displacement curves, without any modification to the standard AFM apparatus. The comparison of the three cell lines show that the non-tumorigenic cells are less deformable and more viscous than cancerous cells, and that cancer cell lines have distinctive viscoelastic properties. In particular, we obtained that ERC−124 > EA−498 > EACHN and ηRC−124 > ηA−498 > ηACHN.
The ovary is perhaps the most dynamic organ in the human body, only rivaled by the uterus. The molecular mechanisms that regulate follicular growth and regression, ensuring ovarian tissue ...homeostasis, remain elusive. We have performed single-cell RNA-sequencing using human adult ovaries to provide a map of the molecular signature of growing and regressing follicular populations. We have identified different types of granulosa and theca cells and detected local production of components of the complement system by (atretic) theca cells and stromal cells. We also have detected a mixture of adaptive and innate immune cells, as well as several types of endothelial and smooth muscle cells to aid the remodeling process. Our results highlight the relevance of mapping whole adult organs at the single-cell level and reflect ongoing efforts to map the human body. The association between complement system and follicular remodeling may provide key insights in reproductive biology and (in)fertility.
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