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The Ganges-Brahmaputra-Meghna (GBM) delta is one of the world's largest deltas. It is currently experiencing high rates of relative sea-level rise of about 5 mm/year, reflecting anthropogenic climate change and land subsidence. This is expected to accelerate further through the 21st Century, so there are concerns that the GBM delta will be progressively submerged. In this context, a core question is: can sedimentation on the delta surface maintain its elevation relative to sea level? This research seeks to answer this question by applying a two-dimensional flow and morphological model which is capable of handling dynamic interactions between the river and floodplain systems and simulating floodplain sedimentation under different flow-sediment regimes and anthropogenic interventions. We find that across a range of flood frequencies and adaptation scenarios (including the natural polder-free state), the retained volume of sediment varies between 22% and 50% of the corresponding sediment input. This translates to average rates of sedimentation on the delta surface of 5.5 mm/yr to 7.5 mm/yr. Hence, under present conditions, sedimentation associated with quasi-natural conditions can exceed current rates of relative sea-level rise and potentially create new land mass. These findings highlight that encouraging quasi-natural conditions through the widespread application of active sediment management measures has the potential to promote more sustainable outcomes for the GBM delta. Practical measures to promote include tidal river management, and appropriate combinations of cross-dams, bandal-like structures, and dredging.

Le Software-Defined Networking (SDN) et la Blockchain sont des technologies de pointe utilisées dans le monde entier pour établir une communication réseau sécurisée ainsi que pour construire des infrastructures réseau sécurisées. Ils fournissent une plate-forme robuste et fiable pour faire face aux menaces et aux défis tels que la sécurité, la confidentialité, la flexibilité, l'évolutivité et la confidentialité. Poussé par ces hypothèses, cet article présente un cadre IoT défini par logiciel optimisé, efficace sur le plan énergétique et sécurisé basé sur la Blockchain pour les réseaux intelligents. En effet, les technologies SDN et Blockchain se sont avérées capables de gérer de manière appropriée l'utilisation des ressources et de développer une communication réseau sécurisée dans l'écosystème IoT. Cependant, il y a un manque de travaux de recherche qui présentent une définition complète d'un tel cadre qui peut répondre aux exigences de l'écosystème IoT (c'est-à-dire une utilisation efficace de l'énergie et un retard de bout en bout réduit). Par conséquent, dans cette recherche, nous présentons une architecture hiérarchique en couches pour le déploiement d'un cadre SDN-IoT distribué mais efficace, compatible Blockchain, qui assure une sélection efficace des têtes de cluster et une communication réseau sécurisée via l'identification et l'isolation des commutateurs rouges. En outre, l'enregistrement des règles de flux compatibles Blockchain garde une trace des règles appliquées dans les commutateurs et maintient la cohérence au sein du cluster de contrôleurs. Enfin, nous évaluons les performances du cadre proposé dans un environnement de simulation et montrons qu'il peut optimiser l'utilisation de l'énergie, le retard de bout en bout et le débit par rapport aux lignes de base considérées, permettant ainsi d'atteindre l'efficacité et la sécurité dans le réseau intelligent. Las redes definidas por software (SDN) y Blockchain son tecnologías líderes utilizadas en todo el mundo para establecer una comunicación de red segura, así como para construir infraestructuras de red seguras. Proporcionan una plataforma sólida y confiable para abordar amenazas y enfrentar desafíos como la seguridad, la privacidad, la flexibilidad, la escalabilidad y la confidencialidad. Impulsado por estos supuestos, este documento presenta un marco optimizado de IoT definido por software basado en Blockchain y energéticamente eficiente para redes inteligentes. De hecho, las tecnologías SDN y Blockchain han demostrado ser capaces de gestionar adecuadamente la utilización de recursos y desarrollar una comunicación de red segura en todo el ecosistema de IoT. Sin embargo, faltan trabajos de investigación que presenten una definición integral de dicho marco que pueda cumplir con los requisitos del ecosistema de IoT (es decir, la utilización eficiente de la energía y la reducción del retraso de extremo a extremo). Por lo tanto, en esta investigación, presentamos una arquitectura jerárquica en capas para el despliegue de un marco SDN-IoT distribuido pero eficiente habilitado para Blockchain que garantiza una selección eficiente de la cabeza del clúster y una comunicación de red segura a través de la identificación y el aislamiento de los switches rouge. Además, el registro de reglas de flujo habilitado para Blockchain realiza un seguimiento de las reglas aplicadas en los switches y mantiene la consistencia dentro del clúster del controlador. Finalmente, evaluamos el rendimiento del marco propuesto en un entorno de simulación y demostramos que puede lograr una utilización optimizada de la energía, un retraso de extremo a extremo y un rendimiento en comparación con las líneas de base consideradas, pudiendo así lograr eficiencia y seguridad en la red inteligente. Software-Defined Networking (SDN) and Blockchain are leading technologies used worldwide to establish safe network communication as well as build secure network infrastructures. They provide a robust and reliable platform to address threats and face challenges such as security, privacy, flexibility, scalability, and confidentiality. Driven by these assumptions, this paper presents an optimized energy-efficient and secure Blockchain-based software-defined IoT framework for smart networks. Indeed, SDN and Blockchain technologies have proven to be able to suitably manage resource utilization and to develop secure network communication across the IoT ecosystem. However, there is a lack of research works that present a comprehensive definition of such a framework that can meet the requirements of the IoT ecosystem (i.e. efficient energy utilization and reduced end-to-end delay). Therefore, in this research, we present a layered hierarchical architecture for the deployment of a distributed yet efficient Blockchain-enabled SDN-IoT framework that ensures efficient cluster-head selection and secure network communication via the identification and isolation of rouge switches. Besides, the Blockchain-enabled flow-rules record keeps track of the rules enforced in the switches and maintains the consistency within the controller cluster. Finally, we assess the performance of the proposed framework in a simulation environment and show that it can achieve optimized energy-utilization, end-to-end delay, and throughput compared to considered baselines, thus being able to achieve efficiency and security in the smart network. تعد الشبكات المعرفة بالبرمجيات (SDN) وسلسلة الكتل (Blockchain) من التقنيات الرائدة المستخدمة في جميع أنحاء العالم لإنشاء اتصالات آمنة للشبكة بالإضافة إلى بناء بنى تحتية آمنة للشبكة. فهي توفر منصة قوية وموثوقة لمواجهة التهديدات ومواجهة التحديات مثل الأمن والخصوصية والمرونة وقابلية التوسع والسرية. وانطلاقًا من هذه الافتراضات، تقدم هذه الورقة البحثية إطارًا محسّنًا موفرًا للطاقة وآمنًا لإنترنت الأشياء للشبكات الذكية قائمًا على برامج البلوك تشين. في الواقع، أثبتت تقنيات SDN و Blockchain أنها قادرة على إدارة استخدام الموارد بشكل مناسب وتطوير اتصالات شبكة آمنة عبر النظام البيئي لإنترنت الأشياء. ومع ذلك، هناك نقص في الأعمال البحثية التي تقدم تعريفًا شاملاً لمثل هذا الإطار الذي يمكن أن يلبي متطلبات النظام البيئي لإنترنت الأشياء (أي الاستخدام الفعال للطاقة وتقليل التأخير من البداية إلى النهاية). لذلك، في هذا البحث، نقدم بنية هرمية متعددة الطبقات لنشر إطار SDN - IoT الموزع والفعال في الوقت نفسه والذي يضمن الاختيار الفعال لرأس المجموعة والاتصال الآمن بالشبكة عبر تحديد وعزل مفاتيح الحمر. إلى جانب ذلك، فإن سجل قواعد التدفق الذي يدعم البلوك تشين يتتبع القواعد المفروضة في المفاتيح ويحافظ على الاتساق داخل مجموعة التحكم. أخيرًا، نقوم بتقييم أداء الإطار المقترح في بيئة محاكاة ونظهر أنه يمكنه تحقيق الاستخدام الأمثل للطاقة والتأخير من البداية إلى النهاية والإنتاجية مقارنة بخطوط الأساس المدروسة، وبالتالي القدرة على تحقيق الكفاءة والأمن في الشبكة الذكية.

High-throughput experimental screening and machine-learning algorithms are implemented in a synergic workflow to predict the photocurrent phase space of organic photovoltaic blends. We identify accurate models employing only the materials band gaps.

Abstract The lack of precipitation for an extended period is what meteorologists call a drought, and it results in low soil moisture and crop water stress. Drought has become one of the most important global challenges due to inadequate water supplies. Drought monitoring is frequently conducted using the SPI (standardized precipitation index) and the SPEI (standardized precipitation evapotranspiration index). The goal of this work is to use SPI and SPEI to investigate the differences in drought characteristics across different physiognomy types in Bangladesh and to highlight how drought characteristics change over time and spatial scales when considering different geomorphologies. This study used monthly precipitation and temperature data from 29 metrological stations for 39 years (1980–2018) for calculating SPI and SPEI values. To determine the significance of drought characteristic trends over different temporal and spatial scales, the modified Mann–Kendall trend test and multivariable linear regression (MLR) techniques were used. The results are as follows: (1) Overall, an increasing dry trend was found in Eastern hill regions, whereas decreasing trends were found rest of the regions in all time scale (range is from − 0.008 year−1 to − 0.015 year−1 for 3-month time scale). However, except for the one-month time scale, the statistically significant trend was identified mostly in the north-central and northeast regions, indicating that drought patterns migrate from the northwest to the center region. (2) Drought intensity increased gradually from the southern to the northern regions (1.26–1.56), and drought events occurred predominantly in the northwestern regions (27–30 times), indicating that drought meteorological hotspots were primarily concentrated in the Barind Tract and Tista River basin over time. (3) According to the MLR, longitude and maximum temperature can both influence precipitation. Findings can be used to improve drought evaluation, hazard management, and application policymaking in Bangladesh. This has implications for agricultural catastrophe prevention and mitigation.

Recently, the integrated landscape approach has gained increasing interest of the scientific community, as well as of organizations active in the field of sustainable development. However, the enthusiastic welcome is challenged by little consensus on theory, terminology and definitions. Moreover, the operationalization of the approach into practice is a major challenge. In this paper, we present a framework to operationalize the integrated landscape approach in practice by putting a long-term collaboration between scientists and various stakeholder at center stage. Based on encompassing understanding of landscape-level processes and interactions, four pillars addressing different steps of a joint-learning circle are described and illustrated with examples. We consider the integrated landscape approach to be a prime way of targeting the Sustainable Development Goals (SDGs), but novel forms of collaboration between scientists and other stakeholders based on long-term commitments will be needed for operationalization in practice.