Bioinspired Intervertebral Disc with Multidirectional Stiffness Prepared via Multimaterial Additive Manufacturing

Degenerative disc disease (DDD) has become a significant public health issue worldwide. This can result in loss of spinal function affecting patient health and quality of life. Artificial total disc replacement (A-TDR) is an effective approach for treating symptomatic DDD that compensates for lost functionality and helps patients perform daily activities. However, because current A-TDR devices lack the unique structure and material characteristics of natural intervertebral discs (IVDs), they fail to replicate the multidirectional stiffness needed to match physiological motions and characterize anisotropic behavior. It is still unclear how the multidirectional stiffness of the disc is affected by structural parameters and material characteristics. Herein, a bioinspired intervertebral disc (BIVD-L) based on a representative human lumbar segment is developed. The proposed BIVD-L reproduces the multidirectional stiffness needed for the most common physiological kinematic behaviors. The results demonstrate that the multidirectional stiffness of the BIVD-L can be regulated by structural and material parameters. The results of this research deepen knowledge of the biomechanical behavior of the human lumbar disc and may provide new inspirations for the design and fabrication of A-TDR devices for both engineering and functional applications.     

Electrocapacitive Deionization: Mechanisms,Electrodes, and Cell Designs

Capacitive deionization (CDI) is an emerging water desalination technology for removing different ionic species from water, which is based on electric charge compensation by these charged species. CDI is becoming popular because it is more energy-efficient and cost-effective than other technologies, such as reverse osmosis and distillation, specifically in dealing with brackish water having low or moderate salt concentrations. Over the past decade, the CDI research field has witnessed significant advances in the used electrode materials, cell architectures, and associated mechanisms for desalination applications. This review article first discusses ion storage/removal mechanisms in carbon and Faradaic materials aided by advanced in situ analysis techniques and computations. It then summarizes research progress toward electrode materials in terms of structure, surface chemistry, and composition. More still, it discusses CDI cell architectures by highlighting their different cell design concepts. Finally, current challenges and future research directions are summarized to provide guidelines for future CDI research.     

双循环策略下岸桥与跨运车的联合调度

集装箱码头采用跨运车能够减少作业环节和码头机械设备的种类与数量,同时缓存区容量的设置至关重要。首先,为降低码头总完工时间、提高码头作业效率,并解决采用跨运车作为水平运输设备与岸桥进行联合装卸作业时产生的时空协调问题,引入了双循环操作策略,对岸桥与跨运车的联合作业序列优化问题进行研究。其次,建立以总完工时间最小化为目标,考虑岸桥与跨运车双循环操作的实际约束、岸桥缓存区容量限制、安全时间等约束的混合整数规划模型。然后,针对传统禁忌搜索（TS）算法的局限性,加入贪婪算法、多种邻域搜索方式、响应性策略,设计了基于贪婪算法的响应性TS算法,并进行了数值实验。实验结果验证了所提模型与算法的有效性。最后,通过对缓存区容量与跨运车数量、岸桥与跨运车配比的实验分析,得出了最优的跨运车数量和缓存区容量、岸桥与跨运车配比。结果表明：与传统码头设备配置相比,双循环策略可减少跨运车使用数量,提高岸桥与跨运车使用率。     

Policy Iteration for Optimal Control of Discrete-Time Time-Varying Nonlinear Systems

Aimed at infinite horizon optimal control problems of discrete time-varying nonlinear systems, in this paper, a new iterative adaptive dynamic programming algorithm, which is the discrete-time time-varying policy iteration (DTTV) algorithm, is developed. The iterative control law is designed to update the iterative value function which approximates the index function of optimal performance. The admissibility of the iterative control law is analyzed. The results show that the iterative value function is non-increasingly convergent to the Bellman-equation optimal solution. To implement the algorithm, neural networks are employed and a new implementation structure is established, which avoids solving the generalized Bellman equation in each iteration. Finally, the optimal control laws for torsional pendulum and inverted pendulum systems are obtained by using the DTTV policy iteration algorithm, where the mass and pendulum bar length are permitted to be time-varying parameters. The effectiveness of the developed method is illustrated by numerical results and comparisons.      

面向Kubernetes的容器立体化监控系统

容器监控是保证容器基础设施正常运行的核心要素之一,然而当前容器监控角度较为单一,尚缺少直观有效的方法协助运维人员快速定位业务容器异常原因.本文设计并实现了一个面向Kubernetes的容器立体化监控系统,通过监控指标相关性分析,把相关性较强的指标作为立体化监控的核心指标提供给运维人员,更好地实现对容器的全局统筹监控.     

集群环境中微服务容器资源特征分析及优化

在集群环境中部署微服务已经成为微服务部署的重要方式.由于不同种类服务对于CPU、内存、磁盘等资源的需求不同,导致集群中的节点产生资源碎片、出现资源消耗倾斜.如何提高集群资源利用率、降低集群能耗,成为继保障服务级别协议(service level agreement, SLA)之后的重大挑战.本文以阿里巴巴集团2021年发布的近两万个微服务的详细跟踪为数据样本,从容器资源使用情况、节点部署特征和资源消耗偏好等多个维度出发,分析其集群资源消耗特征,发现集群中出现了资源消耗倾斜的情况.通过进一步分析节点中容器部署情况发现容器资源分配不合理加剧了这一现象.基于此我们提出了一种使用深度双Q网络的模型,依据上游服务资源需求的实时变化,对容器资源分配进行优化.对比实验结果表明该方法可以在保证服务SLA的情况下有效提高容器资源利用率,改善节点资源消耗倾斜的情况.     

基于Kubernetes的AI调度引擎平台

文中介绍了基于Kubernetes的AI调度引擎平台的设计与实现, 针对当前人工智能调度系统中存在的服务配置复杂, 集群中各节点计算资源利用率不均衡以及系统运维成本高等问题, 本文提出了基于Kubernetes实现容器调度和服务管理的解决方案. 结合AI调度引擎平台的需求, 从功能实现和平台架构等方面设计该平台的各个模块. 同时, 针对Kubernetes无法感知GPU资源的问题, 引入device plugin收集集群中每个节点上的GPU信息并上报给调度器. 此外, 针对Kubernetes调度策略中优选算法只考虑节点本身的资源使用率和均衡度, 未考虑不同类型的应用对节点资源的需求差异, 提出了基于皮尔逊相关系数 (Pearson correlation coefficient, PCC)的优选算法, 通过计算容器资源需求量与节点资源使用率的互补度来决定Pod的调度, 从而保证调度完成后各节点的资源均衡性.     

基于OpenStack的高资源利用率Docker调度模型

在现有OpenStack云平台与Docker容器技术的集成方案中,基于容器初始资源请求的调度模型由于未充分考虑容器运行时的实际资源使用情况,导致资源利用率较低。为满足云计算领域的高资源利用率和低成本需求,构建基于OpenStack云平台的Docker调度模型（DSM）,将其与OpenStack的Keystone、Glance以及Neutron组件的API进行交互,获取创建容器所需的镜像、网络等资源,同时调用Docker Engine提供的API部署容器,对容器生命周期进行高效灵活管控。通过融合初始化模块、资源实时感知模块、容器调度模块、资源实时监测模块和容器迁移模块,并在容器调度模块中利用资源可用度评估与优先级决策调度机制为容器选择最优的计算节点,实现OpenStack云平台中资源的高效利用。实验结果表明,与经典Nova-Docker和Yun集成方案采用的调度模型相比,DSM调度模型在CPU和内存利用率上至少提升38.54、30.17个百分点和38.40、28.69个百分点。     

Computational Parametric Analysis of Cellular Solids with the Miura-Ori Metamaterial Geometry under Quasistatic Compressive Loads

Origami-based metamaterials have widespread application prospects in various industries including aerospace, automotive, flexible electronics, and civil engineering structures. Among the wide range of origami patterns, the fourfold tessellation known as Miura-ori is of particular attraction to engineers and designers. More specifically, researchers have proposed different 3D structures and metamaterials based on the geometric characteristics of this classic origami pattern. Herein, a computational modeling approach for the design and evaluation of 3D cellular solids with the Miura-ori metamaterial geometry which can be of zero or nonzero thicknesses is presented. To this end, first, a range of design alternatives generated based on a numerical parametric model is designed. Next, their mechanical properties and failure behavior under quasistatic axial compressive loads along three perpendicular directions are analyzed. Then, the effects of various geometric parameters on their energy absorption behavior under compression in the most appropriate direction are investigated. The findings of this study provide a basis for future experimental investigations and the potential application of such cellular solids for energy-absorbing purposes.