Self-adaptive strategy based on fuzzy control systems for improving performance in wireless sensors networks

The solutions to cope with new challenges that societies have to face nowadays involve providing smarter daily systems. To achieve this, technology has to evolve and leverage physical systems automatic interactions, with less human intervention. Technological paradigms like Internet of Things (IoT) and Cyber-Physical Systems (CPS) are providing reference models, architectures, approaches and tools that are to support cross-domain solutions. Thus, CPS based solutions will be applied in different application domains like e-Health, Smart Grid, Smart Transportation and so on, to assure the expected response from a complex system that relies on the smooth interaction and cooperation of diverse networked physical systems. The Wireless Sensors Networks (WSN) are a well-known wireless technology that are part of large CPS. The WSN aims at monitoring a physical system, object, (e.g., the environmental condition of a cargo container), and relaying data to the targeted processing element. The WSN communication reliability, as well as a restrained energy consumption, are expected features in a WSN. This paper shows the results obtained in a real WSN deployment, based on SunSPOT nodes, which carries out a fuzzy based control strategy to improve energy consumption while keeping communication reliability and computational resources usage among boundaries

Adaptive Network Coding Scheme for TCP over Wireless Sensor Networks

The purpose of this paper is to develop a network coding scheme to enhance TCP performance in wireless sensor networks. It is well known that TCP performs poorly over wireless links which suffer from packet losses mainly due to the bad channel. To address this problem, it is useful to incorporate network coding into TCP, as network coding can offer significant benefits in terms of throughput, reliability, and robustness. However, the encoding and decoding operations of network coding techniques will bring an additional delay that has a negative effect on applications of wireless sensor networks. In this paper, we propose an adaptive network coding (ANC) scheme which contains two major aspects: the adjustment of the redundancy factor R and the adjustment of the coding window size CW. We dynamically adjust these two parameters depending on the measured packet loss rate, so that the proposed ANC can effectively mask packet losses and reduce the decoding delay of network coding. The performance of our scheme is evaluated by simulations using NS-2 simulator. Compared to other schemes, the ANC not only achieves a good throughput but also has the lowest average delay and the lowest maximum delay in all experimental environments

LBS: A Beacon Synchronization Scheme With Higher Schedulability for IEEE 802.15. 4 Cluster-Tree-Based IoT Applications

[EN] The IEEE 802.15.4 standard is one of the most widely used link layer technology for building Internet of Things (IoT). It specifies several physical layer options and MAC layer for meeting low-power and low-rate requirements of devices deployed in a network of IoT. The standard also specifies a synchronization scheme for devices connected in a star topology, operating in beacon-enabled (BE) mode using periodic beacons. The BE mode facilitates synchronization among devices for data transmission and is suitable for large networks to establish low duty-cycles. Absence of a such a scheme for a cluster-tree network has confined its application only to nonbeacon mode. The challenge here is to schedule beacon frame transmissions of multiple devices in a nonoverlapping manner to avoid beacon collisions. This paper tackles the problem of synchronization by proposing localized beacon synchronization (LBS) scheme, a distributed technique for beacon scheduling in cluster-tree network topologies. LBS uses 2-hop information and association order to compute beacon transmission offsets that better utilize the available time slots, incur fewer transmissions, and is highly scalable. Further, we analytically show that the schedulability of the proposed scheme is higher compared to other related schemes. In addition, we also address the important issue of resynchronization that has been ignored in all of the prior works. The proposed resynchronization mechanisms consider the interdependencies between synchronization and duty-cycling schemes and are shown to significantly lower the synchronization overhead when synchronization among devices is lost.This work was supported by the Science and Engineering Research Board, Department of Science and Technology, Govt. of India, under Grant ECR/2016/001651.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J. (2019). LBS: A Beacon Synchronization Scheme With Higher Schedulability for IEEE 802.15. 4 Cluster-Tree-Based IoT Applications. IEEE Internet of Things. 6(5):8883-8896. https://doi.org/10.1109/JIOT.2019.2924317888388966

Service Differentiated and Adaptive CSMA/CA over IEEE 802.15.4 for Cyber-Physical Systems

Cyber-Physical Systems (CPS) that collect, exchange, manage information, and coordinate actions are an integral part of the Smart Grid. In addition, Quality of Service (QoS) provisioning in CPS, especially in the wireless sensor/actuator networks, plays an essential role in Smart Grid applications. IEEE 802.15.4, which is one of the most widely used communication protocols in this area, still needs to be improved to meet multiple QoS requirements. This is because IEEE 802.15.4 slotted Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) employs static parameter configuration without supporting differentiated services and network self-adaptivity. To address this issue, this paper proposes a priority-based Service Differentiated and Adaptive CSMA/CA (SDA-CSMA/CA) algorithm to provide differentiated QoS for various Smart Grid applications as well as dynamically initialize backoff exponent according to traffic conditions. Simulation results demonstrate that the proposed SDA-CSMA/CA scheme significantly outperforms the IEEE 802.15.4 slotted CSMA/CA in terms of effective data rate, packet loss rate, and average delay

Stochastic optimal adaptive controller and communication protocol design for networked control systems

Networked Control System (NCS) is a recent topic of research wherein the feedback control loops are closed through a real-time communication network. Many design challenges surface in such systems due to network imperfections such as random delays, packet losses, quantization effects and so on. Since existing control techniques are unsuitable for such systems, in this dissertation, a suite of novel stochastic optimal adaptive design methodologies is undertaken for both linear and nonlinear NCS in presence of uncertain system dynamics and unknown network imperfections such as network-induced delays and packet losses. The design is introduced in five papers. In Paper 1, a stochastic optimal adaptive control design is developed for unknown linear NCS with uncertain system dynamics and unknown network imperfections. A value function is adjusted forward-in-time and online, and a novel update law is proposed for tuning value function estimator parameters. Additionally, by using estimated value function, optimal adaptive control law is derived based on adaptive dynamic programming technique. Subsequently, this design methodology is extended to solve stochastic optimal strategies of linear NCS zero-sum games in Paper 2. Since most systems are inherently nonlinear, a novel stochastic optimal adaptive control scheme is then developed in Paper 3 for nonlinear NCS with unknown network imperfections. On the other hand, in Paper 4, the network protocol behavior (e.g. TCP and UDP) are considered and optimal adaptive control design is revisited using output feedback for linear NCS. Finally, Paper 5 explores a co-design framework where both the controller and network scheduling protocol designs are addressed jointly so that proposed scheme can be implemented into next generation Cyber Physical Systems --Abstract, page iv

La gestion de la qualité de service temps-réel dans les réseaux de capteurs sans fil

In the last years, Wireless Sensor Networks ‘WSN’ knew a tremendous evolution which attracted many applications. WSN has several characteristics that make it a unique research field, such as, WSN nodes’ constraints and the unreliable (lossy) wireless communication. The IEEE 802.15.4 standard is the first standard designed for this type of networks known as LR-WPANs ‘Low-Rate Wireless Personal Area Network’. The energy conservation mechanism proposed by the current standard is quite efficient and very flexible. This flexibility comes from the ability to configure different duty cycles to meet specific applications’ requirements. However, this mechanism has a considerable impact on the end-to-end delay. Our approach resolves the energy/delay trade-off by avoiding the storage of the real-time data in the coordinator during sleep time, more particularly in Multi-source Multi-sink networks. A new superframe structure is adopted and a deterministic reception scheduling is used. In this thesis, we also proposed a new WPAN model for the Network Simulator 3 ‘NS-3’.Le monde des réseaux de capteurs sans fil ‘RCSF’ a connu de grands progrès au cours de ces dernières années. Ainsi, les RCSF ont pu intégrer divers champs d’application (environnement, militaire, médecine, domotique ...) dont quelques-uns ayant des exigences en termes de qualité de service ‘QdS’. Cependant, la garantie de la QdS dans un RCSF pose des problèmes de recherche non triviaux, à cause de la nature peu fiable de la communication sans fil et des limitations des ressources des nœuds RCSF (processeur, mémoire, énergie ...). Dans le cadre de cette thèse, nous nous sommes focalisés sur les protocoles MAC afin d’améliorer le support de QdS dans les RCSF. Plus particulièrement, le standard IEEE 802.15.4. Les mécanismes de conservation d’énergie proposés par ce standard sont efficaces et présentent une flexibilité par rapport aux besoins des applications. Néanmoins, le temps de sommeil des nœuds affecte considérablement le délai de communication, donnant naissance à un compromis énergie/délai. Pour résoudre ce problème, nous avons amélioré ce standard pour un meilleur support des applications temps-réel. L’approche proposée permet de réduire le délai de communication de manière significative, même pour de faibles rapports cycliques, grâce au nouveau format de la supertrame. Les performances ont été validées par simulation et sur des plateformes de nœuds RCSF réelles. Nous avons proposé également un modèle de simulation pour le standard IEEE 802.15.4 sous le simulateur NS-3

Endüstri 4.0’ın muhasebeye etkisi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.2011 yılında Almanya'nın açıklamış olduğu Endüstri 4.0 ile yeni bir döneme geçilmiştir. Endüstri 4.0 nesnelerin interneti (IoT), big data, bulut bilişim, siber fiziksel sistemler, arttırılmış gerçeklik, otonom robotlar, akıllı/karanlık fabrikalar ve block chain gibi bir çok alt başlığı içinde barındırmaktadır. Endüstri 4.0 ile üretim zincirindeki tüm halkaların birbiriyle entegre olan, sürekli etkileşim ve iletişim içinde bulunan, sensörler aracılığıyla ortamı algılayabilen, veri toplayan ve analiz ederek ihtiyaçları belirleyen robotlarla üretimin gerçekleştirilmesi sonucunda daha kaliteli, hızlı, esnek ve daha düşük maliyetli üretimin gerçekleştirilmesi tasarlanmaktadır. Ürün geliştirme aşamasında; tasarımdan gerekli malzeme kullanımına, pazarlamadan sevkiyata birçok süreçte daha şeffaf ve birbirine bağlı bir sistem kurulacaktır. Endüstri 4.0'ın piyasaların ve sektörlerin bir çok alanını etkilemesi beklenmektedir. Bu alanlardan biri olan muhasebe mesleğini de etkileyeceği/değiştireceği ortadadır. ERP sistemleriyle donatılmış piyasalardan müşteri talepleriyle ilgili verilerin toplanması ve bu verilerin analizi ile üretime karar verilmesi süreçlerinde, stok döngüsünü sensörler ve yapay zekalar aracılığıyla etkin ve verimli şekilde yönetilmesi sürecinde, üretim esnasında insandan kaynaklı hata payını robotlar aracılığıyla minimuma indirmesi, sanal gerçeklik, sanal fabrika veya 3D yazıcılar aracılığıyla üretilecek ürünün maliyetler çıkmadan önce kontrol edilmesinde, üretim sonucu elde edilen çıktının takibinde ve müşteri tarafından alınan geri bildirimlerin analizinde, tüm bu işlemlerin muhasebe kayıtları, faturalandırılması gibi görevlerin akıllı sistemler aracılığıyla yapılması, sistemden anlık veriler elde edilmesi sayesinde gerçek zamanlı raporlamaya imkan vermesi, denetim kalitesini ve sürekliliği arttırması gibi muhasebe alanında bir çok yenilik, kolaylık ve verimlilik getirmesi beklenmektedir. Bu sebeple bu çalışmada kavramsal açıdan Endüstri 4.0 ve getirdiği yenilikler incelenmiş, günümüz muhasebecilik mesleğine olası etkilerinin neler olabileceği ortaya konulmuştur.A new era was started with the "Industry 4.0" announced by Germany in 2011. Industry 4.0 contain many sub-headings such as IoT, big data, cloud computing, cyber physical systems, augmented reality, autonomous robots, smart/dark factories and block chains. Industry 4.0 integrates all the factors in the production chain, incessant interaction and communication between machine, sensing sensor, determine needs by collecting and analyzing data by robots. Thus, the production process is planned to be realized in a more qualified, fast, flexible and lower cost production. In this way, a more transparent and interconnected system will be established in many processes during product development. Industry 4.0 is expected to affect many areas of markets and sectors. It is obvious that it will affect / change the accounting profession which is one of these areas. In the processes of collecting data related to customer demands from markets equipped with ERP systems and analyzing these data and deciding on production, efficient and efficient management of the stock cycle through sensors and artificial intelligence; minimizing the amount of error caused by the human during production; pre-control of products to be produced through virtual reality, virtual factory and 3D printers; the analysis of the output obtained from the production and the feedback received from the customers; doing task such as accounting and invoicing of all these transactions through smart systems; allowing real-time reporting by taking instant data from the system; increase the quality and continuity of the audit. it is expected to bring many innovations, convenience and efficiency in accounting. For this reason, in this study, it is aimed to examine the concept of Industry 4.0 and its innovations and present the possible effects on the accounting profession