A DQN-Based Cache Strategy for Mobile Edge Networks

The emerging mobile edge networks with content caching capability allows end users to receive information from adjacent edge servers directly instead of a centralized data warehouse,thus the network transmission delay and system throughput can be improved significantly.Since the duplicate content transmissions between edge network and remote cloud can be reduced,the appropriate caching strategy can also improve the system energy efficiency of mobile edge networks to a great extent.This paper focuses on how to improve the network energy efficiency and proposes an intelligent caching strategy according to the cached content distribution model for mobile edge networks based on promising deep reinforcement learning algorithm.The deep neural network(DNN)and Q-learning algorithm are combined to design a deep reinforcement learning framework named as the deep-Q neural network(DQN),in which the DNN is adopted to represent the approximation of action-state value function in the Q-learning solution.The parameters iteration strategies in the proposed DQN algorithm were improved through stochastic gradient descent method,so the DQN algorithm could converge to the optimal solution quickly,and the network performance of the content caching policy can be optimized.The simulation results show that the proposed intelligent DQN-based content cache strategy with enough training steps could improve the energy efficiency of the mobile edge networks significantly.

Biomass Template Derived Boron/Oxygen Co-Doped Carbon Particles as Advanced Anodes for Potassium-Ion Batteries

Among various anode candidates for potassium-ion batteries,carbonaceous materials have attracted significant attention due to their overwhelming advantages including cost-effectiveness and environmental benignity.However,the inferior specific capacity and the sluggish reaction kinetics hinder the further development in this realm.Herein,we report biomass templated synthesis of boron/oxygen heteroatom co-doped carbon particles(BO-CPs)via direct plasma-enhanced chemical vapor deposition.With the combined advantages of abundant active sites,large accessible surface area,and functional groups,BO-CP anode exhibits high reversible specific capacity(426.5 mAh g^(-1)at 0.1 A g^(-1))and excellent rate performance(166.5 mAh g^(-1)at 5 A g^(-1)).The K-ion storage mechanism is probed by operando Raman spectroscopy,ex situ X-ray photoelectron spectroscopy/electrochemical impedance spectroscopy,galvanostatic intermittent titration technique measurements,and theoretical simulations.The synergistic effect of boron and oxygen co-doping greatly facilitates the performance of carbon-based anode,wherein boron dopant improves the conductivity of carbon framework and the oxygen dopant affords ample active sites and thus harvests additional specific capacity.This work is anticipated to propel the development of high-performance anode materials for emerging energy storage devices.

Effects of Diet with Picria fel-tarrae Lour Particle on the Growth Performance, Blood Biochemical Indexes, Immune and Antioxidant Function of Hongguang Yellow Chickens

[Objectives]To investigate the effect of diet with Picria fel-tarrae Lour particle(PFLp)on growth performance,blood biochemical indexes,immune and antioxidant function of Hongguang yellow chickens(HYC).[Methods]80 HYC in age of 1 d were divided into 4 groups randomly and each group was assigned to 5 replicates with 24 chicks in each replicate.Group A was control group fed only basal diet.Group B,C and D were treatment groups and fed diets with 0.125%,0.25%and 0.50%of PFLp respectively during the trial of 49 d.Serum samples were taken from 10 chicks in each group in the age of 21,35 and 49 d respectively and analyzed for biochemical,immune and antioxidant parameters in blood.[Results]ADG from group C in 21 d was increased significantly than that from group A,B and D(P<0.01),and ADG in 35 d from group C was also significantly greater than that from group A,B and D(P<0.05),but not much difference was found on ADG among the 4 groups in 49 d(P>0.05);ADFI from group C in 35 d was significantly higher than that from group A,B and D(P<0.05).ADFI from group C in 21 and 49 d were also higher than that from group A(P>0.05).FCR from group C in 21 d was much better than that from the other three groups(P<0.01).Death rate of group C was 50 percent lower than group A;There was no difference occurred in serum biochemical and immune parameters among the 4 groups during the trial(P>0.05).However,the T-AOC from group C and D in 21 d was enhanced significantly than that from group A and B(P<0.01),and the one from group C in 35 d was also increased greatly than that from group A,B and D(P<0.05).GSH from group C and D in 21 d was much higher than that from group A and B(P<0.05),and the ones from group C and D in 35 d were also significantly higher than those from group A and B(P<0.01).T-SOD in three stages trended up also in group C and D(P>0.05).[Conclusions]The diet with 0.25%PFLp in 21 and 35 d could dramatically improve the growth performance,significantly increase the antioxidant capacity and effectively reduce death rate.Diet with 0.25%PFLp is the most appropriate among the three different additions.

碳纳米管提升氧化亚硅负极稳定性的起源

高容量的SiO (SO)合金基材料是最有希望的下一代锂离子电池负极之一.使用碳纳米管(CNTs)导电添加剂,虽然可以有效地解决SO较差的循环寿命这一难题,然而除了动力学因素之外,其它潜在的作用机理目前仍不明确.在本工作中,一系列的测试结果表明CNTs可以使电极在循环后依然维持完整的导电网络,确保均匀的电化学反应.CNTs也使得电极局部的体积膨胀得到了抑制,从而避免了固态电解质界面的不断生长,活性材料从集流体剥离,甚至析锂.得益于CNTs的上述作用, SO-CNTs负极在0.5 C (1 C=1600 mA g^(-1))下可以稳定循环200次,其容量保持率为96.2%. CNTs的作用机理也进一步地在商业化的SO/石墨复合负极(SO650-CNTs, 1 C=650 mA g^(-1))中得到了验证,SO650-CNTs在1 C下循环400次后容量保持率为80.6%.本工作为导电添加剂的作用机理提出了新的见解,并将有助于加速合金类负极的商业化进程.

悬浮于石墨烯空位/孔洞中的独立纳米结构

在电子束辐照下,石墨烯较易形成空位、孔洞等缺陷,从而捕获外来原子,形成新的结构.由于这些结构具有一些令人兴奋的性质,它们和石墨烯之间的相互作用引起了科研工作者相当大的研究兴趣.本文总结了利用透射电子显微镜在制备和表征悬浮在石墨烯中的独立纳米结构的方法,以及原子分辨率下观察到的此类材料中原子/结构的动态行为过程,讨论了新型金属/非金属掺杂剂对具有不同键结构的石墨烯空位的影响,以及位于石墨烯边缘的单原子/团簇的催化活性.此外,还讨论了独立单原子厚二维团簇/金属/金属烯和二维团簇/金属/金属烯氧化物的动态形成过程.并指出这些纳米结构的形成、稳定性和宏观效应对于新的原子/分子尺度纳米技术的实际应用至关重要.以上数据证实了新型纳米结构的数量不断增加,并预示着相关研究的不断深入.

Synergistic protection of Si anode based on multi-dimensional graphitic carbon skeletons

Inspired by the natural corn structure,a Si@hollow graphene shell@graphene(Si@GS@G)anode material was prepared in which silicon nanoparticles were preliminarily anchored onto the surface of an elastic graphene shell and further constrained using graphene sheets.Hollow graphene oxide shells with abundant surficial hydrogen bonds,which were synthesized using a novel bottom-up method,were used as an intermediate material to anchor positively charged silicon nanoparticles via electrostatic attraction and achieve a rational spatial distribution.The inner hollow graphene shell anchorage and outer graphene constraint synergistically constituted a porous and robust conductive corn-like structure.The as-fabricated Si@GS@G anode afforded efficient electron and ion transport pathways and improved structural stability,thereby enhancing Li+storage capability(505 mAh·g^(−1)at 10 A·g^(−1))and extending the lifespan compared to the single hollow graphene shell or graphene sheet-protected Si anode(72%capacity retention after 500 cycles).The improved kinetics of the Si@GS@G anode were investigated using electro impedance spectroscopy,galvanostatic intermittent titration,and pseudocapacitance contribution rate analysis,and the structural evolution was analyzed using ex situ electron microscopy.This study proposes a novel hollow graphene oxide shell as an activated intermediate material for designing a porous electrode structure that facilitates an enhanced electrochemical performance.

Enhanced performance of Si-based Li-ion batteries through elastic cushioning with hollow graphene shells

Silicon(Si)is a promising anode material for next-generation Li-ion batteries.The nanometer-sized Si could alleviate the pulverization caused by large volume changes during deep cycling.However,compression between agglomerated Si particles causes Si cracking and electrode failure.Considering this,we engineered a mechanical cushioning space between Si particles via elastic hollow graphene shells(GSs)to flexibly buffer volume changes and maintain the stability of the electrode structure.The stress generated from the Si volume expansion during lithiation was mechanically buffered and gently released by compression of the hollow space of the GS.In this Si/GS composite electrode,GS also reduced the local agglomeration of Si particles and effectively improved the overall conductivity.Considering these advantages,the designed Si/GS electrode showed an enhanced cycling performance with more than 1200 mA h g^(-1) at 0.8 A g^(-1) and an excellent rate capability of 1025 mA h g^(-1) at 4 A g^(-1) after 200 cycles.

Learning robust features by extended generative stochastic networks

Deep neural networks have achieved state-of-the-art performance on many object recognition tasks,but they are vulnerable to small adversarial perturbations.In this paper,several extensions of generative stochastic networks(GSNs)are proposed to improve the robustness of neural networks to random noise and adversarial perturbations.Experimental results show that compared to normal GSN method,the extensions using adversarial examples,lateral connections and feedforward networks can improve the performance of GSNs by making the models more resistant to overfitting and noise.

Effect of core stability training on balance in elderly women

Objective:The study investigated the effect of core stability training on balance in elderly women.Method:Sixty female volunteers 61-70 years of age were divided into training(n=30)and control groups(n=30).Core stability training was given to patients in the training group,and walk-ing exercise was given to patients in the control group.The function of static and dynamic balance was detected before training and 30 weeks after training.Results:The time of standing on one foot with eyes closed after training in the training group was significantly longer than the control group,and the stellate balance test with stretching the lower limbs straight ahead,behind,and laterally in the training group was significantly better than the control group.The performance of two lower limbs during the training in the straight ahead di-rection,behind,and to the outer side in the training group was significantly better than the control group.Significant differences also occurred when the left leg was supported on the outer rear,and the right leg was supported on the medial front and rear.Conclusion:Core stability training is more beneficial than walking exercises in improving balance in elderly women.