CSA: Thực hành nông nghiệp thông minh với khí hậu ở Việt Nam

During the last five years, Vietnam has been one of the countries most affected by climate change. Severe typhoons, flooding, cold spells, salinity intrusion, and drought have affected agriculture production across the country, from upland to lowland regions. Fortunately for Vietnam, continuous work in developing climate-smart agriculture has been occurring in research organizations and among innovative farmers and entrepreneurs. Application of various CSA practices and technologies to adapt to the impact of climate change in agriculture production have been expanding. However, there is a need to accelerate the scaling process of these practices and technologies in order to ensure growth of agriculture production and food security, increase income of farmers, make farming climate resilient, and contribute to global climate change mitigation. This book aims to provide basic information to researchers, managers, and technicians and extentionists at different levels on what CSA practices and technologies can be up scaled in different locations in Vietnam

International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS

Etude de la liquéfaction des géomatériaux avec prise en compte de la non saturation

Ces dernières années, de nombreuses études ont concerné le comportement des sables non saturés soumis à des sollicitations dynamiques. Cependant, certains aspects restent encore à éclaircir comme : (i) le comportement sous des sollicitations sismiques avant et après le choc principal et l'effet des chocs précurseurs sur le potentiel de liquéfaction ; (ii) l'effet du degré de saturation sur le Cyclic Stress Ratio ; (iii) l'effet de la non saturation sur la relation CSR-nombre de cycles pour atteindre la liquéfaction des sols denses. Ce travail de recherche tente d’y apporter quelques éléments de réponses.Deux familles d'essais ont été réalisés à l’aide d’un appareil triaxial dynamique pour étudier le comportement dynamique cyclique d’un sable ainsi que sa résistance résiduelle après liquéfaction. La méthode du damage humide a permis de préparer les échantillons. Le degré de saturation initial a été contrôlé à l’aide de la méthode d’application du vide et le suivi du paramètre de Skempton B permet de mesurer le degré de saturation durant l’essai. Il s’ensuit une consolidation et un chargement cyclique étape par étape jusqu’à la liquéfaction, puis un chargement monotone pour étudier la résistance résiduelle.Les résultats montrent que la susceptibilité à la liquéfaction est directement liée au degré de saturation. Après liquéfaction, l’échantillon récupère sa résistance lorsque la pression interstitielle de l'eau se dissipe.Ainsi, le protocole expérimental proposé dans cette étude est bien adapté pour aborder les principaux défis des essais de liquéfaction des sols non saturés.In the last few years, many studies have focused on the behavior of unsaturated sands subjected to dynamic loading. Despite some achievements, much remains unclear about the behavior of unsaturated soil such as: (i) the behavior before and after the main shock and the effect of foreshocks on the liquefaction potential; (ii) the effect of the saturation degree on the CSR (cyclic stress ratio); (iii) in the case of dense soils, what is the effect of unsaturation on the CSR-number of cycles relationship to reach liquefaction? This research work tries to provide some answers to these questions.Two groups of tests were carried out by triaxial dynamic apparatus to survey the sand mechanical behavior when subjected to cyclic loading as well as the residual strength after liquefaction under monotonic loading. All the samples were prepared by the wet tamping method. The vacuum method was used to control the saturation degree of the samples. Then, the Skempton parameter B was used to evaluate the saturation degree of the samples. After that, sample consolidation and cyclic loading were conducted step by step. After that the samples was subjected to the cyclic loading to study the liquefaction and then the monotonic loading to study the residual strength.The results of cyclic loading process show that the liquefaction susceptibility is directly proportional to the sample saturation degree. The results of the monotonic loading show that the strength of sand recuperates when the pore water pressure dissipates after liquefaction.Besides, the experimental protocol established in this study has handled well the main challenges of the unsaturated soil liquefaction tests

Etude de la liquéfaction des géomatériaux avec prise en compte de la non saturation

In the last few years, many studies have focused on the behavior of unsaturated sands subjected to dynamic loading. Despite some achievements, much remains unclear about the behavior of unsaturated soil such as: (i) the behavior before and after the main shock and the effect of foreshocks on the liquefaction potential; (ii) the effect of the saturation degree on the CSR (cyclic stress ratio); (iii) in the case of dense soils, what is the effect of unsaturation on the CSR-number of cycles relationship to reach liquefaction? This research work tries to provide some answers to these questions.Two groups of tests were carried out by triaxial dynamic apparatus to survey the sand mechanical behavior when subjected to cyclic loading as well as the residual strength after liquefaction under monotonic loading. All the samples were prepared by the wet tamping method. The vacuum method was used to control the saturation degree of the samples. Then, the Skempton parameter B was used to evaluate the saturation degree of the samples. After that, sample consolidation and cyclic loading were conducted step by step. After that the samples was subjected to the cyclic loading to study the liquefaction and then the monotonic loading to study the residual strength.The results of cyclic loading process show that the liquefaction susceptibility is directly proportional to the sample saturation degree. The results of the monotonic loading show that the strength of sand recuperates when the pore water pressure dissipates after liquefaction.Besides, the experimental protocol established in this study has handled well the main challenges of the unsaturated soil liquefaction tests.Ces dernières années, de nombreuses études ont concerné le comportement des sables non saturés soumis à des sollicitations dynamiques. Cependant, certains aspects restent encore à éclaircir comme : (i) le comportement sous des sollicitations sismiques avant et après le choc principal et l'effet des chocs précurseurs sur le potentiel de liquéfaction ; (ii) l'effet du degré de saturation sur le Cyclic Stress Ratio ; (iii) l'effet de la non saturation sur la relation CSR-nombre de cycles pour atteindre la liquéfaction des sols denses. Ce travail de recherche tente d’y apporter quelques éléments de réponses.Deux familles d'essais ont été réalisés à l’aide d’un appareil triaxial dynamique pour étudier le comportement dynamique cyclique d’un sable ainsi que sa résistance résiduelle après liquéfaction. La méthode du damage humide a permis de préparer les échantillons. Le degré de saturation initial a été contrôlé à l’aide de la méthode d’application du vide et le suivi du paramètre de Skempton B permet de mesurer le degré de saturation durant l’essai. Il s’ensuit une consolidation et un chargement cyclique étape par étape jusqu’à la liquéfaction, puis un chargement monotone pour étudier la résistance résiduelle.Les résultats montrent que la susceptibilité à la liquéfaction est directement liée au degré de saturation. Après liquéfaction, l’échantillon récupère sa résistance lorsque la pression interstitielle de l'eau se dissipe.Ainsi, le protocole expérimental proposé dans cette étude est bien adapté pour aborder les principaux défis des essais de liquéfaction des sols non saturés

Etude de la liquéfaction des géomatériaux avec prise en compte de la non saturation

In the last few years, many studies have focused on the behavior of unsaturated sands subjected to dynamic loading. Despite some achievements, much remains unclear about the behavior of unsaturated soil such as: (i) the behavior before and after the main shock and the effect of foreshocks on the liquefaction potential; (ii) the effect of the saturation degree on the CSR (cyclic stress ratio); (iii) in the case of dense soils, what is the effect of unsaturation on the CSR-number of cycles relationship to reach liquefaction? This research work tries to provide some answers to these questions.Two groups of tests were carried out by triaxial dynamic apparatus to survey the sand mechanical behavior when subjected to cyclic loading as well as the residual strength after liquefaction under monotonic loading. All the samples were prepared by the wet tamping method. The vacuum method was used to control the saturation degree of the samples. Then, the Skempton parameter B was used to evaluate the saturation degree of the samples. After that, sample consolidation and cyclic loading were conducted step by step. After that the samples was subjected to the cyclic loading to study the liquefaction and then the monotonic loading to study the residual strength.The results of cyclic loading process show that the liquefaction susceptibility is directly proportional to the sample saturation degree. The results of the monotonic loading show that the strength of sand recuperates when the pore water pressure dissipates after liquefaction.Besides, the experimental protocol established in this study has handled well the main challenges of the unsaturated soil liquefaction tests.Ces dernières années, de nombreuses études ont concerné le comportement des sables non saturés soumis à des sollicitations dynamiques. Cependant, certains aspects restent encore à éclaircir comme : (i) le comportement sous des sollicitations sismiques avant et après le choc principal et l'effet des chocs précurseurs sur le potentiel de liquéfaction ; (ii) l'effet du degré de saturation sur le Cyclic Stress Ratio ; (iii) l'effet de la non saturation sur la relation CSR-nombre de cycles pour atteindre la liquéfaction des sols denses. Ce travail de recherche tente d’y apporter quelques éléments de réponses.Deux familles d'essais ont été réalisés à l’aide d’un appareil triaxial dynamique pour étudier le comportement dynamique cyclique d’un sable ainsi que sa résistance résiduelle après liquéfaction. La méthode du damage humide a permis de préparer les échantillons. Le degré de saturation initial a été contrôlé à l’aide de la méthode d’application du vide et le suivi du paramètre de Skempton B permet de mesurer le degré de saturation durant l’essai. Il s’ensuit une consolidation et un chargement cyclique étape par étape jusqu’à la liquéfaction, puis un chargement monotone pour étudier la résistance résiduelle.Les résultats montrent que la susceptibilité à la liquéfaction est directement liée au degré de saturation. Après liquéfaction, l’échantillon récupère sa résistance lorsque la pression interstitielle de l'eau se dissipe.Ainsi, le protocole expérimental proposé dans cette étude est bien adapté pour aborder les principaux défis des essais de liquéfaction des sols non saturés

Joint Full-Duplex/Half-Duplex Transmission-Switching Scheduling and Transmission-Energy Allocation in Cognitive Radio Networks with Energy Harvesting

The full-duplex transmission protocol has been widely investigated in the literature in order to improve radio spectrum usage efficiency. Unfortunately, due to the effect of imperfect self-interference suppression, the change in transmission power and path loss of non-line-of-sight fading channels will strongly affect performance of full-duplex transmission mode. This entails that the full-duplex transmission protocol is not always a better selection compared to the traditional half-duplex transmission protocol. Considering solar energy-harvesting-powered cognitive radio networks (CRNs), we investigate a joint full-duplex/half-duplex transmission switching scheduling and transmission power allocation in which we utilize the advantages of both half-duplex and full-duplex transmission modes for maximizing the long-term throughput of cognitive radio networks. First, we formulate the transmission rate of half-duplex and full-duplex links for fading channels between cognitive user and base station in which the channel gain is assumed to follow an exponential distribution. Afterward, by considering the availability probability of the primary channel, the limitation of the energy-harvesting capacity of the cognitive user, and the transmission capacity of half-duplex and full-duplex links, we describe the problem in terms of long-term expected throughput. The problem is then solved by adopting the partially observable Markov decision process framework to find the optimal transmission policy for the transmission pair between cognitive user and base station in order to maximize the long-term expected throughput. The optimal policy consists of either the half-duplex or the full-duplex transmission protocols as well as the corresponding amount of transmission energy in each time slot. In addition, to reduce the complexity in formulation and calculation, we also apply the actor–critic-based learning method to solve the considered problem. Finally, the performance of the proposed scheme was evaluated by comparing it with a conventional scheme in which the context of energy harvesting and long-term throughput is not considered

Multichannel-Sensing Scheduling and Transmission-Energy Optimizing in Cognitive Radio Networks with Energy Harvesting

This paper considers cognitive radio networks (CRNs) utilizing multiple time-slotted primary channels in which cognitive users (CUs) are powered by energy harvesters. The CUs are under the consideration that hardware constraints on radio devices only allow them to sense and transmit on one channel at a time. For a scenario where the arrival of harvested energy packets and the battery capacity are finite, we propose a scheme to optimize (i) the channel-sensing schedule (consisting of finding the optimal action (silent or active) and sensing order of channels) and (ii) the optimal transmission energy set corresponding to the channels in the sensing order for the operation of the CU in order to maximize the expected throughput of the CRN over multiple time slots. Frequency-switching delay, energy-switching cost, correlation in spectrum occupancy across time and frequency and errors in spectrum sensing are also considered in this work. The performance of the proposed scheme is evaluated via simulation. The simulation results show that the throughput of the proposed scheme is greatly improved, in comparison to related schemes in the literature. The collision ratio on the primary channels is also investigated

Cache-Enabled Data Rate Maximization for Solar-Powered UAV Communication Systems

Currently, deploying fixed terrestrial infrastructures is not cost-effective in temporary circumstances, such as natural disasters, hotspots, and so on. Thus, we consider a system of caching-based UAV-assisted communications between multiple ground users (GUs) and a local station (LS). Specifically, a UAV is exploited to cache data from the LS and then serve GUs’ requests to handle the issue of unavailable or damaged links from the LS to the GUs. The UAV can harvest solar energy for its operation. We investigate joint cache scheduling and power allocation schemes by using the non-orthogonal multiple access (NOMA) technique to maximize the long-term downlink rate. Two scenarios for the network are taken into account. In the first, the harvested energy distribution of the GUs is assumed to be known, and we propose a partially observable Markov decision process framework such that the UAV can allocate optimal transmission power for each GU based on proper content caching over each flight period. In the second scenario where the UAV does not know the environment’s dynamics in advance, an actor-critic-based scheme is proposed to achieve a solution by learning with a dynamic environment. Afterwards, the simulation results verify the effectiveness of the proposed methods, compared to baseline approaches