1,721,065 research outputs found
Enumeration and Identification of Active Users for Grant-Free NOMA Using Deep Neural Networks
Full text linkIn next-generation mobile radio systems, multiple access schemes will support a massive number of uncoordinated devices exhibiting sporadic traffic, transmitting short packets to a base station. Grant-free non-orthogonal multiple access (NOMA) has been introduced to provide services to a large number of devices and to reduce the communication overhead in massive machine-type communication (mMTC) scenarios. In grant-free communication, there is no coordination between the device and base station (BS) before the data transmission; therefore, the challenging task of active users detection (AUD) must be conducted at the BS. For NOMA with sparse spreading, we propose a deep neural network (DNN)-based approach for AUD called active users enumeration and identification (AUEI). It consists of two phases: firstly, a DNN is used to estimate the number of active users; then in the second phase, another DNN identifies them. To speed up the training process of the DNNs, we propose a multi-stage transfer learning technique. Our numerical results show a remarkable performance improvement of AUEI in comparison to previously proposed approaches
Blind User Activity Detection for Grant-Free Random Access in Cell-Free mMIMO Networks
No full textCell-free massive MIMO (CF-mMIMO) networks have recently emerged as a promising solution to tackle the challenges arising from next-generation massive machine-type communications. In this paper, a fully grant-free deep learning (DL)-based method for user activity detection in CF-mMIMO networks is proposed. Initially, the known non-orthogonal pilot sequences are used to estimate the channel coefficients between each user and the access points. Then, a deep convolutional neural network is used to estimate the activity status of the users. The proposed method is 'blind', i.e., it is fully data-driven and does not require prior large-scale fading coefficients estimation. Numerical results show how the proposed DL-based algorithm is able to merge the information gathered by the distributed antennas to estimate the user activity status, yet outperforming a state-of-the-art covariance-based method
Recent developments and challenges in biomass cookstove
Full text linkThe growing demand for more efficient cooking methods has been fueled by the rapid advancements in biomass utilization. Considerable progress has been made in the development of a biomass cookstove that is both highly thermally efficient and produces less pollution. This review provides a comprehensive overview of the current status and advancements in biomass cookstove technologies. It explores various types of biomass cookstoves, with a particular focus on advanced models available in the market. The paper explores the recent advancements, highlighting the effectiveness of ceramic materials in combustion chambers for reducing emissions, and the impact of introducing swirl vanes and hybrid air injection systems on fuel consumption and overall performance. The review also discusses the important design strategies and limitations that affect the efficiency of these cookstoves. In addition, it acknowledges the considerable challenges in the field, such as design limitations, maintenance, and performance testing variations. Given recent advancements in biomass cookstove technologies, this review identifies important areas for future research. Although there have been significant research in the field of biomass cookstove, there are still gaps in the literature, particularly when it comes to complex heat transfer mechanism. These gaps in knowledge emphasize the need for further investigation to develop more practical and efficient cooking technologies
Phytochemical and pharmacological attributes of piperine: A bioactive ingredient of black pepper
No full textPlants are vital for the wellbeing of humankind in a variety of ways. Some plant extracts contain antimicrobial properties that can treat different pathogens. Most of the world's population relies on medicinal plants and natural products for their primary health care needs. Therefore, there is a growing interest in natural products, medicinal plants, and traditional medicine along with a desire to design and develop novel plant-based pharmaceuticals. These plant-based pharmaceuticals may address the concerns of reduced efficacy of synthetic antibiotics due to the emergence of drug-resistant pathogens. In this regard, some plant extracts from black pepper (Piper nigrum) with antimicrobial properties, including piperine, have the potential to be used as natural dietary supplements together with modern therapeutic approaches. This review highlights possible applications of piperine as the active compound in the fields of rational drug design and discovery, pharmaceutical chemistry, and biomedicine. We discuss different extraction methods and pharmacological effects of the analyzed substance to pave the way for further research strategies and perspectives towards the development of novel herbal products for better healthcare solutions
First insight into the levels and distribution of flame retardants in potable water in Pakistan: An underestimated problem with an associated health risk diagnosis
No full textTo date, very little is known about the occurrence of flame retardants (FRs) in potable water and its associated health risk to the exposed human population. The current study was designed to investigate the differences in the contamination levels of selected FRs in the potable water of industrial, rural and background zones of Pakistan. In addition, the health risk assessment for the exposed human population was estimated. For this purpose, the concentrations of the selected FRs: polybrominated diphenylethers (PBDEs), dechlorane plus (DP), novel brominated flame retardants (NBFRs) and organophosphate flame retardants (OPFRs), were analyzed in a total of 39 samples of potablewater from the above mentioned three zones. We found elevated concentrations of Sigma OPFRs (BDL-71.05 ng/L), Sigma PBDEs (BDL-0.82 pg/L), Sigma NBFRs (BDL-1.39 pg/L) and Sigma DP (BDL-0.29 pg/L) in the potable water samples from industrial zones, smaller concentrations in the samples from rural zones, and negligible concentrations in the samples from background zones. Among all the FRs analyzed, Tris-(2-chloroisopropyl)-phosphate (Sigma TCPP), anti-DP, BDE-47 and 1.2-bis(pentabromodiphenyl) ethane (DBDPE) were the dominant compounds in all three selected zones. Principal component analysis (PCA) revealed that most of the FRs are associated with the industrial zones. The estimated daily intake (EDI) for all selected FRs was found to be higher in children than adults. However, both children and adults were found to be at low risk (i.e., Hazard quotient (HQ) < 1) of FRs exposure through potable water consumption. We predict that FRs might be leached out from wastewater bodies and subsequently mixed with nearby potable water facilities. FRs may also spill out from the aluminum or plastic pipes and tanks most commonly used for potable water storage in Pakistan. The present study suggests initiating measures to minimize human exposure to FRs in the future. (C) 2016 Elsevier B.V. All rights reserved
New insight into the levels, distribution and health risk diagnosis of indoor and outdoor dust-bound FRs in colder, rural and industrial zones of Pakistan
No full textThis is the first robust study designed to probe selected flame retardants (FRs) in the indoor and outdoor dust of industrial, rural and background zones of Pakistan with special emphasis upon their occurrence, distribution and associated health risk. For this purpose, we analyzed FRs such as polybrominated diphenylethers (PBDEs), dechlorane plus (DP), novel brominated flame retardants (NBFRs) and organophosphate flame retardants (OPFRs) in the total of 82 dust samples (indoor and outdoor) collected three from each zone: industrial, rural and background. We found higher concentrations of FRs (PBDEs, DP, NBFRs and OPFRs) in industrial zones as compared to the rural and background zones. Our results reveal that the concentrations of studied FRs are relatively higher in the indoor dust samples being compared with the outdoor dust and they are ranked as: Sigma OPFRs > Sigma NBFRs > Sigma PBDEs > Sigma DP. A significant correlation in the FRs levels between the indoor and outdoor dust suggest the potential intermixing of these compounds between them. The principal component analysis/multiple linear regression predicts the percent contribution of FRs from different consumer products in. the indoor and outdoor dust of industrial, rural and background zones to trace their source origin. The FRs detected in the background zones reveal the dust-bound FRs suspended in the air might be shifted from different warmer zones or consumers products available/used in the same zones. Hazard quotient (HQ) for FRs via indoor and outdoor dust intake at mean and high dust scenarios to the exposed populations (adults and toddlers) are found free of risk (HQ < 1) in the target zones. Furthermore, our nascent results will provide a baseline record of FRs (PBDEs, DP, NBFRs and OPFRs) concentrations in the indoor and outdoor dust of Pakistan. (C) 2016 Elsevier Ltd. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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