Identity-based edge computing anonymous authentication protocol

With the development of sensor technology and wireless communication technology, edge computing has a wider range of applications. The privacy protection of edge computing is of great significance. In the edge computing system, in order to ensure the credibility of the source of terminal data, mobile edge computing (MEC) needs to verify the signature of the terminal node on the data. During the signature process, the computing power of edge devices such as wireless terminals can easily become the bottleneck of system performance. Therefore, it is very necessary to improve efficiency through computational offloading. Therefore, this paper proposes an identity-based edge computing anonymous authentication protocol. The protocol realizes mutual authentication and obtains a shared key by encrypting the mutual information. The encryption algorithm is implemented through a thresholded identity-based proxy ring signature. When a large number of terminals offload computing, MEC can set the priority of offloading tasks according to the user’s identity and permissions, thereby improving offloading efficiency. Security analysis shows that the scheme can guarantee the anonymity and unforgeability of signatures. The probability of a malicious node forging a signature is equivalent to cracking the discrete logarithm puzzle. According to the efficiency analysis, in the case of MEC offloading, the computational complexity is significantly reduced, the computing power of edge devices is liberated, and the signature efficiency is improved

Hydrogen (H2) generation from hydrogen atom-rich molecules catalyzed by transition-metal nanoalloys and the boosting role of visible light using gold plasmon

L'utilisation des sources d'énergie d'origine fossile produit des gaz à effet de serre dangereux en raison du réchauffement climatique qu'ils provoquent et une pollution considérable dommageable pour la santé humaine. C'est pourquoi il existe une énorme demande de sources d'énergies alternatives telles que H2 dont la combustion ne produit que de l'eau. Cependant, les risques d'explosion doivent être pris en compte. C'est pourquoi le stockage de H2 dans des petites molécules stables telles que NaBH4 ou l'ammonia-borane (AB) libérant H2 par hydrolyse pourrait constituer une solution. Cependant, la lenteur de ces réactions nécessite le développement de catalyseurs efficaces. Cette thèse adresse ce défi en cinq chapitres de recherche démontrant la mise au point de nouveaux nano-catalyseurs très efficaces avec des systèmes solubles dans l'eau de type “dendrizymes” ou des catalyseurs hétérogènes.Dans le 1er chapitre, sont reporté des nano-catalyseurs efficaces pour l'hydrolyse de NaBH4 supportés par des dendrimères “click”, c'est-à-dire synthétisés par catalyse au Cu(I) de la cycloaddition d'azotures en terminaison de branches dendritiques avec des dendrons comportant un alcyne au point focal. Les connecteurs triazole ainsi formés servent de ligands doux stabilisant les nanocatalyseurs de l'hydrolyse de NaBH4. Les meilleurs catalyseurs sont des nano-alliages Pt-Co (1/1).Dans le 2ème chapitre, H2 est généré par hydrolyse de NaBH4 ou AB catalysée par des nano-alliages Au-métal de transition stabilisés comme au premier chapitre, mais la présence d'or permet d'accélérer les réactions par transfert d'électron chaud de l'or vers le métal actif grâce au plasmon de l'or excité en lumière visible. Cet enrichissement du métal actif permet l'addition oxydante de la liaison O-H de l'eau en surface. Les meilleurs métaux sont Rh, Ru et Pt et, parmi les métaux abondants, Co.Dans le 3ème chapitre, les MOF de type réseaux zéolite imidazolate (ZIF) sont utilisés comme catalyseurs hétérogènes en impliquant à nouveau l'effet accélérateur de la lumière visible grâce à l'excitation du plasmon de l'or dans les nano-alliages Au-Ni pour lesquels une synergie très positive en catalyse est aussi démontrée. La fréquence de nombres de tours catalytiques est ainsi 3,4 plus grande qu'avec Ni@ZIF-8 seul dans le noir. Les calculs DFT et les mesures cinétiques confirment que l'un des atomes de H2 provient du borane et l'autre de l'eau dont la coupure est l'étape déterminante de la réaction.Dans le 4ème chapitre, le support hétérogène ZIF-8 est de nouveau utilisé pour la production de H2 par méthanolyse de AB catalysée par les nano-alliages Au-Pd en tandem avec la semi-hydrogénation des alcynes (sélective et d'importance industrielle). L'irradiation en lumière visible qui excite le plasmon de l'or permet d'accélérer à la fois les deux réactions en jeu par enrichissement du site Pd, lequel provoque ainsi plus facilement l'addition oxydante de la coupure de la liaison O-H du méthanol dont l'étude cinétique montre qu'elle constitue l'étape déterminante pour la vitesse de la méthanolyse.Dans le 5ème chapitre, des complexes sandwich du fer sont comparés comme réservoirs recyclables de H2. Les complexes neutres riches en hydrure réagissent avec le méthanol ou l'éthanol en présence de catalyseur commercial Pd/C en générant H2 et les complexes du fer pauvres en hydrure (l'un des atomes H de H2 provient de l'alcool). A l'inverse, ces derniers régénèrent les complexes riches en hydrure en présence de H2 et de Pd/C dans le THF.En conclusion, de nouveaux nanocatalyseurs et photocatalyseurs très efficaces ont été mis au point et optimisés, générant H2 par hydrolyse ou méthanolyse de molécules riches en atomes H dans des conditions ambiantes, et des complexes du fer ont été testés comme réservoirs de H2.The utilization of fossil fuels produce dangerous greenhouse gas responsible for global warming and considerable pollution very damageable for human health, and therefore there is a huge demand for clean energy sources such as H2. whose combustion product is water. However, giving the dangers of explosion, large-scale application of H2 involves storage issues. H2 evolution upon hydrolysis of stable hydrogen storage materials appears as a valuable option. Given the very low reaction rate of NaBH4 and ammonia borane (AB) hydrolysis under ambient conditions, acceleration by catalysts is regarded as a promising way.In five research chapters, the PhD has addressed this challenging problem in designing novel very efficient catalyst systems both in dendrizyme like aqueous system and heterogeneous solid-state nanomaterials. In the first chapter, we have disclosed efficient click-dendrimer-supported synergistic bimetallic nanocatalysis for H2 evolution by NaBH4 hydrolysis. The concept involved" water-soluble “click"-dendrimers synthesized by copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) between azido-terminated dendrimers and dendrons containing an alkynyl group at the focal point forming 1,2,3-triazolyl links that mildly stabilize nanocatalysts for drastic acceleration of NaBH4 hydrolysis. Remarkable synergy was disclosed between Pt and Co with an optimized ratio of 1:1.In the second chapter, we have retained NaBH4 and AB hydrolysis as H2 sources using gold-late transition metal nanoalloys stabilized by the same water-soluble dendrimers, but the introduction of gold allowed us to investigate its plasmonic effect boosting nanocatalysis upon visible-light irradiation. This boosting effect is rationalized by transfer of plasmon-induced hot electron from the Au atoms to the other metal atoms facilitating water O-H oxidative addition on the metal surface (best metals: Rh, Ru, Pt; among the cheap metals: Co) in the rate-determining step.In the third chapter, heterogeneous systems with metal organic frameworks (MOFs) of zeolitic imidazolate framework (ZIF) type have been used to examine the light effect in Au-Ni@ZIF-8. Catalyzed AB hydrolysis was boosted by the selective gold plasmon irradiation and also accelerated by the dramatic volcano-type synergy between Au and Ni in their alloys. The tunover frequency was 3.4 times higher with light than with Ni@ZIF-8 in the dark. Mechanistic studies including kinetics and DFT calculation supported water cleavage as the rate-limiting step, and deuteration experiments confirmed that one H of H2 came from AB, and the other from water. In the fourth chapter, the same heterogeneous support as in chapter 3, ZIF-8, was utilized for AuPd alloy-catalyzed AB methanolysis to H2 employed in tandem with alkyne semi-hydrogenation, a very useful and selective reaction, and both reactions were boosted by visible-light illumination due to plasmon-induced electron transfer from Au to the Pd active site for methanol O-H cleavage as the rate-limiting step.In the fifth, last chapter, an iron sandwich system is shown to serve as a reversible H2 reservoir. First, a hydride-rich complex produces H2 and the hydride-poor complex upon Pd/C catalysis in methanol or ethanol (one of the H's from H2 comes from this alcohol), then the later reacts with H2 in THF using the same catalyst to give back the hydride-rich complex. The mechanisms of both reactions are still being explored.In conclusion, these studies have adressed the crucial sustainable energy-related H2 production from small H-atom-rich molecules (including H2O) under ambient conditions including the synergistic roles of the alloyed metals, gold plasmon, support, boosting light effects and detailed mechanistic investigations. As a result, very efficient and fast H2 generation systems have been disclosed

Génération de H2 à partir de molécules riches en atomes d'hydrogène catalysée par des nano-alliages et accélération de ces réactions par la lumière visible grâce au plasmon de l'or

L'utilisation des sources d'énergie d'origine fossile produit des gaz à effet de serre dangereux en raison du réchauffement climatique qu'ils provoquent et une pollution considérable dommageable pour la santé humaine. C'est pourquoi il existe une énorme demande de sources d'énergies alternatives telles que H2 dont la combustion ne produit que de l'eau. Cependant, les risques d'explosion doivent être pris en compte. C'est pourquoi le stockage de H2 dans des petites molécules stables telles que NaBH4 ou l'ammonia-borane (AB) libérant H2 par hydrolyse pourrait constituer une solution. Cependant, la lenteur de ces réactions nécessite le développement de catalyseurs efficaces. Cette thèse adresse ce défi en cinq chapitres de recherche démontrant la mise au point de nouveaux nano-catalyseurs très efficaces avec des systèmes solubles dans l'eau de type “dendrizymes” ou des catalyseurs hétérogènes.Dans le 1er chapitre, sont reporté des nano-catalyseurs efficaces pour l'hydrolyse de NaBH4 supportés par des dendrimères “click”, c'est-à-dire synthétisés par catalyse au Cu(I) de la cycloaddition d'azotures en terminaison de branches dendritiques avec des dendrons comportant un alcyne au point focal. Les connecteurs triazole ainsi formés servent de ligands doux stabilisant les nanocatalyseurs de l'hydrolyse de NaBH4. Les meilleurs catalyseurs sont des nano-alliages Pt-Co (1/1).Dans le 2ème chapitre, H2 est généré par hydrolyse de NaBH4 ou AB catalysée par des nano-alliages Au-métal de transition stabilisés comme au premier chapitre, mais la présence d'or permet d'accélérer les réactions par transfert d'électron chaud de l'or vers le métal actif grâce au plasmon de l'or excité en lumière visible. Cet enrichissement du métal actif permet l'addition oxydante de la liaison O-H de l'eau en surface. Les meilleurs métaux sont Rh, Ru et Pt et, parmi les métaux abondants, Co.Dans le 3ème chapitre, les MOF de type réseaux zéolite imidazolate (ZIF) sont utilisés comme catalyseurs hétérogènes en impliquant à nouveau l'effet accélérateur de la lumière visible grâce à l'excitation du plasmon de l'or dans les nano-alliages Au-Ni pour lesquels une synergie très positive en catalyse est aussi démontrée. La fréquence de nombres de tours catalytiques est ainsi 3,4 plus grande qu'avec Ni@ZIF-8 seul dans le noir. Les calculs DFT et les mesures cinétiques confirment que l'un des atomes de H2 provient du borane et l'autre de l'eau dont la coupure est l'étape déterminante de la réaction.Dans le 4ème chapitre, le support hétérogène ZIF-8 est de nouveau utilisé pour la production de H2 par méthanolyse de AB catalysée par les nano-alliages Au-Pd en tandem avec la semi-hydrogénation des alcynes (sélective et d'importance industrielle). L'irradiation en lumière visible qui excite le plasmon de l'or permet d'accélérer à la fois les deux réactions en jeu par enrichissement du site Pd, lequel provoque ainsi plus facilement l'addition oxydante de la coupure de la liaison O-H du méthanol dont l'étude cinétique montre qu'elle constitue l'étape déterminante pour la vitesse de la méthanolyse.Dans le 5ème chapitre, des complexes sandwich du fer sont comparés comme réservoirs recyclables de H2. Les complexes neutres riches en hydrure réagissent avec le méthanol ou l'éthanol en présence de catalyseur commercial Pd/C en générant H2 et les complexes du fer pauvres en hydrure (l'un des atomes H de H2 provient de l'alcool). A l'inverse, ces derniers régénèrent les complexes riches en hydrure en présence de H2 et de Pd/C dans le THF.En conclusion, de nouveaux nanocatalyseurs et photocatalyseurs très efficaces ont été mis au point et optimisés, générant H2 par hydrolyse ou méthanolyse de molécules riches en atomes H dans des conditions ambiantes, et des complexes du fer ont été testés comme réservoirs de H2.The utilization of fossil fuels produce dangerous greenhouse gas responsible for global warming and considerable pollution very damageable for human health, and therefore there is a huge demand for clean energy sources such as H2. whose combustion product is water. However, giving the dangers of explosion, large-scale application of H2 involves storage issues. H2 evolution upon hydrolysis of stable hydrogen storage materials appears as a valuable option. Given the very low reaction rate of NaBH4 and ammonia borane (AB) hydrolysis under ambient conditions, acceleration by catalysts is regarded as a promising way.In five research chapters, the PhD has addressed this challenging problem in designing novel very efficient catalyst systems both in dendrizyme like aqueous system and heterogeneous solid-state nanomaterials. In the first chapter, we have disclosed efficient click-dendrimer-supported synergistic bimetallic nanocatalysis for H2 evolution by NaBH4 hydrolysis. The concept involved" water-soluble “click"-dendrimers synthesized by copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) between azido-terminated dendrimers and dendrons containing an alkynyl group at the focal point forming 1,2,3-triazolyl links that mildly stabilize nanocatalysts for drastic acceleration of NaBH4 hydrolysis. Remarkable synergy was disclosed between Pt and Co with an optimized ratio of 1:1.In the second chapter, we have retained NaBH4 and AB hydrolysis as H2 sources using gold-late transition metal nanoalloys stabilized by the same water-soluble dendrimers, but the introduction of gold allowed us to investigate its plasmonic effect boosting nanocatalysis upon visible-light irradiation. This boosting effect is rationalized by transfer of plasmon-induced hot electron from the Au atoms to the other metal atoms facilitating water O-H oxidative addition on the metal surface (best metals: Rh, Ru, Pt; among the cheap metals: Co) in the rate-determining step.In the third chapter, heterogeneous systems with metal organic frameworks (MOFs) of zeolitic imidazolate framework (ZIF) type have been used to examine the light effect in Au-Ni@ZIF-8. Catalyzed AB hydrolysis was boosted by the selective gold plasmon irradiation and also accelerated by the dramatic volcano-type synergy between Au and Ni in their alloys. The tunover frequency was 3.4 times higher with light than with Ni@ZIF-8 in the dark. Mechanistic studies including kinetics and DFT calculation supported water cleavage as the rate-limiting step, and deuteration experiments confirmed that one H of H2 came from AB, and the other from water. In the fourth chapter, the same heterogeneous support as in chapter 3, ZIF-8, was utilized for AuPd alloy-catalyzed AB methanolysis to H2 employed in tandem with alkyne semi-hydrogenation, a very useful and selective reaction, and both reactions were boosted by visible-light illumination due to plasmon-induced electron transfer from Au to the Pd active site for methanol O-H cleavage as the rate-limiting step.In the fifth, last chapter, an iron sandwich system is shown to serve as a reversible H2 reservoir. First, a hydride-rich complex produces H2 and the hydride-poor complex upon Pd/C catalysis in methanol or ethanol (one of the H's from H2 comes from this alcohol), then the later reacts with H2 in THF using the same catalyst to give back the hydride-rich complex. The mechanisms of both reactions are still being explored.In conclusion, these studies have adressed the crucial sustainable energy-related H2 production from small H-atom-rich molecules (including H2O) under ambient conditions including the synergistic roles of the alloyed metals, gold plasmon, support, boosting light effects and detailed mechanistic investigations. As a result, very efficient and fast H2 generation systems have been disclosed

Hybrid Treatment of An Enlarging Hypogastric Aneurysm Previously Excluded During Abdominal Aortic Aneurysm Repair

Hypogastric aneurysm is rare, often asymptomatic, but associated with high mortality if it ruptures. Given the deep location of the artery and proximity to critical anatomical structures (i.e. ureter, bladder, rectum), open surgical repair carries high morbidity and mortality compared to an endovascular approach. We report a simple hybrid approach to repair an enlarging isolated hypogastric aneurysm following a previous aortic aneurysm repair during which the origin of the hypogastric artery was ligated

Knowledge-Aided Structured Covariance Matrix Estimator Applied for Radar Sensor Signal Detection

This study deals with the problem of covariance matrix estimation for radar sensor signal detection applications with insufficient secondary data in non-Gaussian clutter. According to the Euclidean mean, the authors combined an available prior covariance matrix with the persymmetric structure covariance estimator, symmetric structure covariance estimator, and Toeplitz structure covariance estimator, respectively, to derive three knowledge-aided structured covariance estimators. At the analysis stage, the authors assess the performance of the proposed estimators in estimation accuracy and detection probability. The analysis is conducted both on the simulated data and real sea clutter data collected by the IPIX radar sensor system. The results show that the knowledge-aided Toeplitz structure covariance estimator (KA-T) has the best performance both in estimation and detection, and the knowledge-aided persymmetric structure covariance estimator (KA-P) has similar performance with the knowledge-aided symmetric structure covariance estimator (KA-S). Moreover, compared with existing knowledge-aided estimator, the proposed estimators can obtain better performance when secondary data are insufficient

Hydrogen Evolution upon Ammonia Borane Solvolysis: Comparison between the Hydrolysis and Methanolysis Reactions

Hydrogen (H2) production is a key challenge for green carbon-free sustainable energy. Among the H2 evolution methods from H-rich materials, ammonia borane (AB) solvolysis stands as a privileged source under ambient and sub-ambient conditions given its stability, non-toxicity, and solubility in protic solvents, provided suitable and optimized nanocatalysts are used. In this paper dedicated to Prof. Avelino Corma, we comparatively review AB hydrolysis and alcoholysis (mostly methanolysis) in terms of nanocatalyst performances and discuss the advantages and inconveniences of these two AB solvolysis methods including AB regeneration

Penetrating aortic ulcer and aortic intramural hematoma: Treatment strategy

Objectives The indication, timing, and choice of the treatment modality for penetrating aortic ulcers (PAUs) and intramural hematoma (IMH) are frequently challenging. This article reviews these pathologies and their relation to aortic dissection and proposes a diagnostic and treatment algorithm. Methods A review of literature on diagnosis and treatment of PAU and IMH was conducted. The PubMed database was searched using the terms “penetrating aortic ulcer” and “aortic intramural hematoma”. Articles were reviewed and the studies involving diagnosis and management of PAU and IMH were included. We subsequently proposed a management algorithm for PAU and IMH based on available evidence. Results PAU and IMH are distinct entities from aortic dissection, although they carry a significant risk of progression into dissection, aneurysm, and rupture. PAU and IMH originating in zone 0 of the aorta generally require surgical treatment. When the origin is beyond zone 0, a trial of medical therapy is recommended. Progression of disease on imaging studies, persistent uncontrolled pain, and certain high-risk features warrant surgery. High-risk features signaling risk of disease progression include PAU with IMH, PAU depth more than 10 mm, PAU diameter more than 20 mm, IMH thickness more than 10 mm, and maximum initial aortic diameter more than 40 mm. Conclusions High-quality evidence regarding the treatment of PAU and IMH is lacking. These entities can have a malignant course when they are present with associated symptoms and/or when they have associated high-risk features on imaging. An aggressive surgical approach is necessary in that group of patients

Clutter Covariance Matrix Estimation for Radar Adaptive Detection Based on a Complex-Valued Convolutional Neural Network

In this paper, we address the problem of covariance matrix estimation for radar adaptive detection under non-Gaussian clutter. Traditional model-based estimators may suffer from performance loss due to the mismatch between real data and assumed models. Therefore, we resort to a data-driven deep-learning method and propose a covariance matrix estimation method based on a complex-valued convolutional neural network (CV-CNN). Moreover, a real-valued (RV) network with the same framework as the proposed CV network is also constructed to serve as a natural competitor. The obtained clutter covariance matrix estimation based on the network is applied to the adaptive normalized matched filter (ANMF) detector for performance assessment. The detection results via both simulated and real sea clutter illustrate that the estimator based on CV-CNN outperforms other traditional model-based estimators as well as its RV competitor in terms of probability of detection (PD)

Staged Treatment for an Unusual Case of Median Arcuate Ligament Syndrome Caused by Compression of the Celiac and Superior Mesenteric Arteries

We report the unusual presentation of a patient with median arcuate ligament syndrome (MALS) and compression of both the celiac artery and the superior mesenteric artery (SMA). He underwent a staged treatment. First, a laparoscopic release of the median arcuate ligament was performed. In the second stage, due to persistent postprandial pain, the SMA was stented, resulting in complete symptom relief. Recognizing this rare anatomical presentation is very important to avoiding MALS misdiagnosis and providing the appropriate staged treatment