As more and more mobile devices rely on cloud services since the introduction of cloud computing, data privacy has emerged as one of the most pressing security concerns. Users typically encrypt their ...important data before uploading it to cloud servers to safeguard data privacy, which makes data usage challenging. On the other side, this also increases the possibility of brand-new issues in cities. A clever, effective and efficient urban monitoring system is required to address possible challenges that may arise in urban settings. In the smart city concept, which makes use of sensors, one strategy that might be used in IoT and cloud computing is to monitor and gather data on problems that develop in cities in real-time. However, it will take a while and be rather expensive to install IoT and sensors throughout the city. The Mobile Crowd-Sensing (MCS) method is proposed to be used in this study to retrieve and gather data on issues that arise in metropolitan areas from citizen reports made using mobile devices. And we suggest a budget-constrained, reputation-based collaborative user recruitment (RCUR) procedure for a MCS system. To construct an edge-assisted MCS system in urban situations, we first integrate edge computing into MCS. We also examine how user reputation affects user recruitment. Finally, we create a collaborative sensing approach using the edge nodes’ sensing capabilities.
This paper describes an OWL-based ontology to manage the data and artifacts created as part of software development projects based on the ECSS-E-ST-40C standard for SW development. ECSS standards are ...the main reference in aerospace projects. ECSS-E-ST-40C establishes the process, activities, requirements, and work products that must be generated. As part of its requirements, ECSS-E-ST-40C implicitly refers to specific data that must be generated, collected, and managed. The ontology identifies these data and the relationships that are inferred from the requirements in the standard, intending to set up the basis for building advanced information systems where data coming from different projects can be integrated and connected into a coherent set. The definition of this ontology provides the conceptual framework to develop data exchange processes and interfaces between the different tools and information systems used by the different players in the aerospace industry.
•Design of Electric Core Simulator System for large sodium facility is described.•Using equivalent property concept, the Peak Cladding Temperature (PCT) characteristic was conserved within reasonable ...range.•Thermal-fluidic behavior (heat transfer and pressure drop) was conserved.
The second phase of STELLA program (STELLA-2) has been started to verify and validate the performance of DHRS of PGSFR, and the construction of the facility is expected to be completed in 2019. The STELLA-2 is not only aimed for investigation of decay heat removal characteristics but also demonstrates its performance while interacting with PHTS of pool-type design. For comprehensive understanding of the phenomena, all systems and components of significance in the reactor need to be modeled as closely as possible and the core is one of such significant areas to be taken into account. To simulate the thermal-fluidic behavior and to observe the Peak Cladding Temperature (PCT) phenomena in core, the Electric Core Simulator System (ECSS) has been designed through similarity consideration by the scaling analysis with conservation of dimensionless number groups under the global/local scaling law. In this paper, the design consideration and process of the electric heater rod and the ECSS is described. The equivalent property concept was introduced and the thermal-fluidic behavior in PHTS pool was also conserved. Finally, the ECSS design was evaluated by MARS-LMR code and the comparison result between reactor core and that of ECSS in STELLA-2 is also described.
Single atom catalysts (SACs) have attracted considerable attention due to their unique structures and excellent catalytic performance, especially in the area of catalysis science and energy ...conversion and storage. In recent years, SACs have emerged as a new type of sensing material for constructing electrochemical sensors (ECSs), presenting excellent sensitivity, selectivity, and stability. Herein, we review the recent advances of SACs in electrochemical sensing and discuss the status quo of current SAC-based ECSs. Specifically, the fundamentals of SAC-based ECSs are outlined, including the involved central metal atoms and various supports of SACs in this field, the detection mechanisms, and improving strategies of SAC-based ECSs. Moreover, the important applications of SAC-based ECSs are listed and classified, covering the detection of reactive oxygen and nitrogen species, environmental pollutants, disease biomarkers, and pharmaceuticals. Last, based on abundant reported cases, the current conundrums of SAC-based ECSs are summarized, and the prediction of their future developing trends is also put forward.
This paper addresses the tradeoff problem between hit ratio and content quality in edge caching systems for multiuser adaptive bitrate streaming (ABS) services. A dynamic policy for cache decision ...and quality level selection for each ABS content during every cache cycle is proposed. Achieving this policy is NP-complete. For this, the considered problem is transformed into a nested multidimensional 0/1 knapsack optimization problem which is then resolved by a cooperative transfer learning-accelerated genetic algorithm. Performance evaluation demonstrates an adaptation of the proposed algorithm on various video stream popularity models in terms of algorithmic convergence and cache balancing.
The motivation for conducting this research stems from the increasingly applied manipulations of emission control systems (ECSs), especially those in diesel passenger cars (PCs). The study aimed to ...investigate the influence of manipulations of exhaust gas recirculation (EGR) valves and a diesel exhaust fluid (DEF)-dosing system on the nitrogen oxide (NOX) emissions of a Euro 6 diesel vehicle and, through the quantification of vehicles with manipulated ECSs, estimate the emissions of Euro 6 diesel PCs. Portable emissions measurement system (PEMS) measurements were performed on a Euro 6 diesel vehicle at a constant speed and on real driving emission (RDE) routes. The speed-dependent functions of the NOX hot emission factor (EF) were calculated for seven different scenarios. The results showed that the NOX EFs for the worst-case scenarios were more than two orders of magnitude higher than those where all ECSs were active. Applying the calculated EFs and the survey answers on the percentage of manipulated PCs to the Croatian Euro 6 diesel PC fleet, the results showed that the emission levels were up to 46.3% higher than the emissions calculated by the official computer program COPERT v5.6.5, with a tendency towards significantly higher values. The main conclusion is that vehicle manufacturers, policymakers, and the general public need to be informed about the enormous damage that in-use vehicles with manipulated ECSs cause to the environment and human health, in order to prevent such actions.
Requirements document relations Großer, Katharina; Riediger, Volker; Jürjens, Jan
Software and systems modeling,
12/2022, Letnik:
21, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Relations between requirements are part of nearly every requirements engineering approach. Yet, relations of views, such as requirements documents, are scarcely considered. This is remarkable as ...requirements documents and their structure are a key factor in requirements reuse, which is still challenging. Explicit formalized relations between documents can help to ensure consistency, improve completeness, and facilitate review activities in general. For example, this is relevant in space engineering, where many challenges related to complex document dependencies occur: 1. Several contractors contribute to a project. 2. Requirements from standards have to be applied in several projects. 3. Requirements from previous phases have to be reused. We exploit the concept of “layered traceability”, explicitly considering documents as views on sets of individual requirements and specific traceability relations on and between all of these representation layers. Different types of relations and their dependencies are investigated with a special focus on requirement reuse through standards and formalized in an Object-Role Modelling (ORM) conceptual model. Automated analyses of requirement graphs based on this model are able to reveal document inconsistencies. We show examples of such queries in Neo4J/Cypher for the EagleEye case study. This work aims to be a step toward a better support to handle highly complex requirement document dependencies in large projects with a special focus on requirements reuse and to enable automated quality checks on dependent documents to facilitate requirements reviews.
The development process of on-board software applications can benefit from model-driven engineering techniques. Model validation and model transformations can be applied to drive the activities of ...specification, requirements definition, and system-level validation and verification according to the space software engineering standards ECSS-E-ST-40 and ECSS-Q-ST-80. This paper presents a model-driven approach to completing these activities by avoiding inconsistencies between the documents that support them and providing the ability to automatically generate the system-level validation tests that are run on the Ground Support Equipment and the matrices required to complete the software verification. A demonstrator of the approach has been built using as a proof of concept a subset of the functionality of the software of the control unit of the Energetic Particle Detector instrument on-board Solar Orbiter.
With the ever growing capabilities of space-grade FPGAs and microcontrollers, spacecraft systems are evolving from centralized architectures with a single main processing unit to decentralized ...layouts composed of multiple intelligent nodes. The backbone of this development is the command and control bus that interconnects these units. Used in terrestrial applications since decades, the CAN bus provides performance and robustness similar to other more traditional spacecraft buses such as MIL-STD-1553, but at very low cost. The European Cooperation for Space Standardization has published a standard in mid 2015 that specifies the requirements for a CAN bus system for space application. In this paper we present the details and results of a prototype implementation of this standard for CubeSat missions. We demonstrate that the minimal implementation of this protocol stack can well be adapted to the tight constraints of microcontrollers. The main advantages of this standardized CAN bus are increased reliability and higher data throughput, as compared to other commonly employed bus systems on CubeSats.
PDF
