Improvement effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)on hydrogen storage performance of MgH_(2)

The hydrogen absorption/desorption kinetic properties of MgH_(2)can be effectively enhanced by doping specific catalysts.In this work,MOFs-derived NiCu@C nanoparticles(~15 nm)with regular core-shell structure were successfully prepared and introduced into MgH_(2)(denoted as MgH_(2)-NiCu@C).The onset and peak temperatures of hydrogen desorption of MgH_(2)-11 wt.%NiCu@C are 175.0℃and282.2℃,respectively.The apparent activation energy of dehydrogenated reaction is 77.2±4.5 kJ/mol for MgH_(2)-11 wt.%NiCu@C,which is lower than half of that of the as-milled MgH_(2).Moreover,MgH_(2)-11 wt.%NiCu@C displays great cyclic stability.The strengthening"hydrogen pumping"effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)is proposed to explain the remarkable improvement in hydrogen absorption/desorption kinetic properties of MgH_(2).This work offers a novel perspective for the design of bimetallic nanoparticles and beyond for application in hydrogen storage and other energy related fields.

Poisoning attacks and countermeasures in intelligent networks:Status quo and prospects

Over the past years,the emergence of intelligent networks empowered by machine learning techniques has brought great facilitates to different aspects of human life.However,using machine learning in intelligent networks also presents potential security and privacy threats.A common practice is the so-called poisoning attacks where malicious users inject fake training data with the aim of corrupting the learned model.In this survey,we comprehensively review existing poisoning attacks as well as the countermeasures in intelligent networks for the first time.We emphasize and compare the principles of the formal poisoning attacks employed in different categories of learning algorithms,and analyze the strengths and limitations of corresponding defense methods in a compact form.We also highlight some remaining challenges and future directions in the attack-defense confrontation to promote further research in this emerging yet promising area.

Assisting Ni catalysis by CeO_(2) with oxygen vacancy to optimize the hydrogen storage properties of MgH_(2)

Although MgH_(2) has been widely regarded as a promising material for solid-state hydrogen storage,its high operating temperature and slow kinetics pose a major bottleneck to its practical application.Here,a nanocomposite catalyst with interfacial coupling and oxygen defects,Ni/CeO_(2),is fabricated to promote H_(2) desorption and absorption properties of MgH_(2).The interface of Ni/CeO_(2) contributes to both strong mechanical coupling towards stabilizing partial Ni and electronic coupling towards inducing a high con-centration of oxygen vacancies in CeO_(2).Theoretical calculations evidence that CeO_(2) with oxygen vacancy assist Ni in weakening the energy of Mg-H bond as well as enhancing the adsorption energy of Ni upon hydrogen atoms,and the extent of this assistance surprisingly increases with increasing oxygen vacancies concentration.As a result,an impressive performance is achieved by MgH_(2)-5 wt.%Ni/CeO_(2) with onset desorption temperature of only 165°C,and it absorbs approximately 80%hydrogen in just 800 s at 125°C.The generation mechanism of intermediate active species concerning Ni/CeO_(2) in different states has been analyzed for the first time,and the relationship between interfacial coupling and phase evolution has been elucidated.Therefore,a mechanism of the catalysis-assisting effect regarding oxygen defects is proposed.It is believed that this work provides a unique perspective on the mechanism of interfacial coupling and the generation of defects in composite catalysts.

Gaze-Assisted Viewport Control for 360° Video on Smartphone

360° video has been becoming one of the major media in recent years, providing immersive experience for viewers with more interactions compared with traditional videos. Most of today's implementations rely on bulky Head-Mounted Displays (HMDs) or require touch screen operations for interactive display, which are not only expensive but also inconvenient for viewers. In this paper, we demonstrate that interactive 360° video streaming can be done with hints from gaze movement detected by the front camera of today's mobile devices (e.g., a smartphone). We design a lightweight real-time gaze point tracking method for this purpose. We integrate it with streaming module and apply a dynamic margin adaption algorithm to minimize the overall energy consumption for battery-constrained mobile devices. Our experiments on state-of-the-art smartphones show the feasibility of our solution and its energy efficiency toward cost-effective real-time 360° video streaming.