scholarly journals Virtual Knowledge Graphs: An Overview of Systems and Use Cases

2019 ◽  
Vol 1 (3) ◽  
pp. 201-223 ◽  
Author(s):  
Guohui Xiao ◽  
Linfang Ding ◽  
Benjamin Cogrel ◽  
Diego Calvanese
Keyword(s):  
Data Integration ◽  
Domain Knowledge ◽  
Data Access ◽  
Use Cases ◽  
Future Research ◽  
Knowledge Graph ◽  
Research Directions ◽  
Wide Range ◽  
Future Research Directions ◽  
Knowledge Graphs

In this paper, we present the virtual knowledge graph (VKG) paradigm for data integration and access, also known in the literature as Ontology-based Data Access. Instead of structuring the integration layer as a collection of relational tables, the VKG paradigm replaces the rigid structure of tables with the flexibility of graphs that are kept virtual and embed domain knowledge. We explain the main notions of this paradigm, its tooling ecosystem and significant use cases in a wide range of applications. Finally, we discuss future research directions.

scholarly journals A matrix-less method to approximate the spectrum and the spectral function of Toeplitz matrices with real eigenvalues

2021 ◽  
Author(s):  
Sven-Erik Ekström ◽  
Paris Vassalos
Keyword(s):  
Distribution Function ◽  
Asymptotic Distribution ◽  
Numerical Experiments ◽  
Toeplitz Matrices ◽  
Future Research ◽  
Research Directions ◽  
Numerical Examples ◽  
Working Hypothesis ◽  
Wide Range ◽  
Future Research Directions

AbstractIt is known that the generating function f of a sequence of Toeplitz matrices {Tn(f)}n may not describe the asymptotic distribution of the eigenvalues of Tn(f) if f is not real. In this paper, we assume as a working hypothesis that, if the eigenvalues of Tn(f) are real for all n, then they admit an asymptotic expansion of the same type as considered in previous works, where the first function, called the eigenvalue symbol $\mathfrak {f}$ f , appearing in this expansion is real and describes the asymptotic distribution of the eigenvalues of Tn(f). This eigenvalue symbol $\mathfrak {f}$ f is in general not known in closed form. After validating this working hypothesis through a number of numerical experiments, we propose a matrix-less algorithm in order to approximate the eigenvalue distribution function $\mathfrak {f}$ f . The proposed algorithm, which opposed to previous versions, does not need any information about neither f nor $\mathfrak {f}$ f is tested on a wide range of numerical examples; in some cases, we are even able to find the analytical expression of $\mathfrak {f}$ f . Future research directions are outlined at the end of the paper.

scholarly journals CubeSat Communications: Recent Advances and Future Challenges

2020 ◽  
Author(s):  
Nasir Saeed ◽  
Ahmed Elzanaty ◽  
Heba Almorad ◽  
Hayssam Dahrouj ◽  
Tareq Y. Al-Naffouri ◽  
...  
Keyword(s):  
Channel Modeling ◽  
Future Research ◽  
New Paradigm ◽  
Earth Remote Sensing ◽  
Research Directions ◽  
Space Industry ◽  
Recent Advances ◽  
Wide Range ◽  
Future Challenges ◽  
Future Research Directions

<pre><pre>Given the increasing number of space-related applications, research in the emerging space industry is becoming more and more attractive. One compelling area of current space research is the design of miniaturized satellites, known as CubeSats, which are enticing because of their numerous applications and low design-and-deployment cost. </pre><pre>The new paradigm of connected space through CubeSats makes possible a wide range of applications, such as Earth remote sensing, space exploration, and rural connectivity.</pre><pre>CubeSats further provide a complementary connectivity solution to the pervasive Internet of Things (IoT) networks, leading to a globally connected cyber-physical system.</pre><pre>This paper presents a holistic overview of various aspects of CubeSat missions and provides a thorough review of the topic from both academic and industrial perspectives.</pre><pre>We further present recent advances in the area of CubeSat communications, with an emphasis on constellation-and-coverage issues, channel modeling, modulation and coding, and networking.</pre><pre>Finally, we identify several future research directions for CubeSat communications, including Internet of space things, low-power long-range networks, and machine learning for CubeSat resource allocation.</pre></pre>

scholarly journals A Systematic Survey on Deep Generative Models for Graph Generation

2020 ◽  
Author(s):  
Xiaojie Guo ◽  
Liang Zhao
Keyword(s):  
Generative Models ◽  
Future Research ◽  
Specific Domain ◽  
Research Directions ◽  
Wide Range ◽  
Data Representations ◽  
Future Research Directions ◽  
Definition Of ◽  
Rich History ◽  
Graph Generation

Graphs are important data representations for describing objects and their relationships, which appear in a wide diversity of real-world scenarios. As one of a critical problem in this area, graph generation considers learning the distributions of given graphs and generating more novel graphs. Owing to its wide range of applications, generative models for graphs have a rich history, which, however, are traditionally hand-crafted and only capable of modeling a few statistical properties of graphs. Recent advances in deep generative models for graph generation is an important step towards improving the fidelity of generated graphs and paves the way for new kinds of applications. This article provides an extensive overview of the literature in the field of deep generative models for graph generation. Firstly, the formal definition of deep generative models for the graph generation as well as preliminary knowledge is provided. Secondly, two taxonomies of deep generative models for unconditional, and conditional graph generation respectively are proposed; the existing works of each are compared and analyzed. After that, an overview of the evaluation metrics in this specific domain is provided. Finally, the applications that deep graph generation enables are summarized and five promising future research directions are highlighted.

Modern Downsizing

2021 ◽  
pp. 1970-1983
Author(s):  
Grzegorz Wojtkowiak
Keyword(s):  
Financial Analysis ◽  
Management Tool ◽  
Future Research ◽  
Research Directions ◽  
Good Practices ◽  
Strategic Option ◽  
Wide Range ◽  
Future Research Directions ◽  
Points Of View

The aim of the chapter is to present the concept of downsizing from different points of view: as a strategic option, as a management tool and as a phenomenon. It describes the evolution of the term, its definitions, and different directions of development. A scale and possible outcomes are described on the basis of financial analysis; however it also discusses the role of non-financial aspects. The chapter points out reasons, aims and a wide range of tools that may be used during implementation of downsizing. One of the conclusions of the chapter is to present future research directions aiming at increasing knowledge of managers and providing them with detailed good practices.

Blockchain Towards Secure UAV-Based Systems

2021 ◽  
pp. 149-174
Author(s):  
lamia Chaari Fourati ◽  
Mohamed Fourati ◽  
Bilel Najeh ◽  
Aicha Idriss
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Use Cases ◽  
Future Research ◽  
Research Directions ◽  
Smart Systems ◽  
Aerial Vehicles ◽  
Future Research Directions ◽  
New Challenges

During this last decade, the blockchain (BC) paradigm has been required in several use cases and scenarios in particular for security, privacy, and trust provisioning. Accordingly, several studies proposed the use of BC technology to secure and to assure the trustworthiness of unmanned aerial vehicles (UAVs). In this context, this chapter highlights several applications and scenarios for the deployment of UAVs within diverse smart systems. In addition, it illustrates the advantages of the integration of the BC within UAVs-based smart systems. This integration reveals new challenges and future research directions that are discussed in this chapter.

Aspects of battle damage repair of helicopter structures

2010 ◽  
Vol 114 (1155) ◽  
pp. 321-332 ◽  
Author(s):  
J. Wang ◽  
A. Baker
Keyword(s):  
Composite Structures ◽  
Future Research ◽  
Research Directions ◽  
Strength Assessment ◽  
Damage Prediction ◽  
Damage Repair ◽  
Repair Materials ◽  
Wide Range ◽  
Future Research Directions ◽  
Non Destructive

Abstract This paper summarises recent research conducted at the Defence Science and Technology Organisation in the area of aircraft battle damage repair, covering aspects such as ballistic testing, ballistic damage prediction, non-destructive damage inspection, structure residual-strength assessment, repair materials and techniques, repair design approaches, repair implementation and demonstration. The research has been focused on military helicopter composite structures. This paper provides an overview of a wide range of research conducted and detailed information in selected areas. Considerations for future research directions are also briefly discussed.

Perinatal Depression

2014 ◽  
Author(s):  
Jennifer N. Felder ◽  
Abigail Lindemann ◽  
Sona Dimidjian
Keyword(s):  
Risk Factors ◽  
Perinatal Depression ◽  
Perinatal Period ◽  
Future Research ◽  
Childbearing Age ◽  
Research Directions ◽  
Wide Range ◽  
Assessment And Treatment ◽  
Future Research Directions ◽  
Assessment Strategies

Depression is a common problem among pregnant andpostpartum women, with rates comparable to or greater than those among women of childbearing age who are not pregnant or postpartum. Perinatal depression is associated with a wide range of unique assessment and treatment complexities, risk factors, and consequences for women and offspring. In this chapter, we review current research on the prevalence of perinatal depression, etiology, risk factors, and consequences, and we discuss assessment strategies and interventions. Limitations to current research and future research directions are noted. We conclude with guidelines for practitioners for assessing and treating depression during the perinatal period.

scholarly journals A Survey on Blockchain Interoperability: Past, Present, and Future Trends

2022 ◽  
Vol 54 (8) ◽  
pp. 1-41
Author(s):  
Rafael Belchior ◽  
André Vasconcelos ◽  
Sérgio Guerreiro ◽  
Miguel Correia
Keyword(s):  
Literature Review ◽  
Grey Literature ◽  
Use Cases ◽  
Future Research ◽  
Future Trends ◽  
Research Directions ◽  
Blockchain Technology ◽  
Future Research Directions ◽  
The Way

Blockchain interoperability is emerging as one of the crucial features of blockchain technology, but the knowledge necessary for achieving it is fragmented. This fact makes it challenging for academics and the industry to achieve interoperability among blockchains seamlessly. Given this new domain’s novelty and potential, we conduct a literature review on blockchain interoperability by collecting 284 papers and 120 grey literature documents, constituting a corpus of 404 documents. From those 404 documents, we systematically analyzed and discussed 102 documents, including peer-reviewed papers and grey literature. Our review classifies studies in three categories: Public Connectors, Blockchain of Blockchains, and Hybrid Connectors. Each category is further divided into sub-categories based on defined criteria. We classify 67 existing solutions in one sub-category using the Blockchain Interoperability Framework, providing a holistic overview of blockchain interoperability. Our findings show that blockchain interoperability has a much broader spectrum than cryptocurrencies and cross-chain asset transfers. Finally, this article discusses supporting technologies, standards, use cases, open challenges, and future research directions, paving the way for research in the area.

scholarly journals Person Search Challenges and Solutions: A Survey

2021 ◽  
Author(s):  
Xiangtan Lin ◽  
Pengzhen Ren ◽  
Yun Xiao ◽  
Xiaojun Chang ◽  
Alex Hauptmann
Keyword(s):  
Free Form ◽  
Future Research ◽  
Search Query ◽  
Research Directions ◽  
Wide Range ◽  
Person Features ◽  
Real World Applications ◽  
Person Search ◽  
Future Research Directions ◽  
Open Issues

Person search has drawn increasing attention due to its real-world applications and research significance. Person search aims to find a probe person in a gallery of scene images with a wide range of applications, such as criminals search, multicamera tracking, missing person search, etc. Early person search works focused on image-based person search, which uses person image as the search query. Text-based person search is another major person search category that uses free-form natural language as the search query. Person search is challenging, and corresponding solutions are diverse and complex. Therefore, systematic surveys on this topic are essential. This paper surveyed the recent works on image-based and text-based person search from the perspective of challenges and solutions. Specifically, we provide a brief analysis of highly influential person search methods considering the three significant challenges: the discriminative person features, the query-person gap, and the detection-identification inconsistency. We summarise and compare evaluation results. Finally, we discuss open issues and some promising future research directions.

scholarly journals Solid Lubrication with MoS2: A Review

Lubricants ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 57 ◽  
Author(s):  
Mohammad R. Vazirisereshk ◽  
Ashlie Martini ◽  
David A. Strubbe ◽  
Mehmet Z. Baykara
Keyword(s):  
Temperature Dependence ◽  
Molybdenum Disulfide ◽  
Solid Lubricants ◽  
Solid Lubrication ◽  
Future Research ◽  
Research Directions ◽  
Space Industry ◽  
Structure Synthesis ◽  
Wide Range ◽  
Future Research Directions

Molybdenum disulfide (MoS2) is one of the most broadly utilized solid lubricants with a wide range of applications, including but not limited to those in the aerospace/space industry. Here we present a focused review of solid lubrication with MoS2 by highlighting its structure, synthesis, applications and the fundamental mechanisms underlying its lubricative properties, together with a discussion of their environmental and temperature dependence. The review also includes an extensive overview of the structure and tribological properties of doped MoS2, followed by a discussion of potential future research directions.

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