原子层制造的研究现状与科学挑战

原子层制造是指加工精度达到原子层量级的可控制造技术,包括原子层去除、添加、迁移等。针对信息、能源、航空航天等领域核心零部件超高性能构建的发展需求,通过原子层可控去除制造全频段原子级精度无损表面,并结合原子层增材制造原子级新结构,有望实现特殊功能的有效创成,保证超高性能的安全可靠。另外,后摩尔时代先进芯片的制造工艺将迈入亚纳米物理极限,原子层制造需求贯穿芯片制造工艺的全流程。本文阐述了原子层制造技术的发展需求与研究进展,围绕原子层抛光、原子层沉积/刻蚀、原子层损伤控制、原子层工艺与装备等领域,梳理了原子层制造的发展方向及研究目标,凝练了原子层制造领域未来的关键科学问题及面临的挑战,探讨了前沿研究方向和发展战略。

Surface form inspection with contact coordinate measurement:a review

Parts with high-quality freeform surfaces have been widely used in industries,which require strict quality control during the manufacturing process.Among all the industrial inspection methods,contact measurement with coordinate measuring machines or computer numerical control machine tool is a fundamental technique due to its high accuracy,robustness,and universality.In this paper,the existing research in the contact measurement field is systematically reviewed.First,different configurations of the measuring machines are introduced in detail,which may have influence on the corresponding sampling and inspection path generation criteria.Then,the entire inspection pipeline is divided into two stages,namely the pre-inspection and post-inspection stages.The typical methods of each sub-stage are systematically overviewed and classified,including sampling,accessibility analysis,inspection path generation,probe tip radius compensation,surface reconstruction,and uncertainty analysis.Apart from those classical research,the applications of the emerging deep learning technique in some specific tasks of measurement are introduced.Furthermore,some potential and promising trends are provided for future investigation.

Position Errors and Interference Prediction-Based Trajectory Tracking for Snake Robots

This work presents a trajectory tracking control method for snake robots.This method eliminates the influence of time-varying interferences on the body and reduces the offset error of a robot with a predetermined trajectory.The optimized line-of-sight(LOS)guidance strategy drives the robot’s steering angle to maintain its anti-sideslip ability by predicting position errors and interferences.Then,the predictions of system parameters and viscous friction coefficients can compensate for the joint torque control input.The compensation is adopted to enhance the compatibility of a robot within ever-changing environments.Simulation and experimental outcomes show that our work can decrease the fluctuation peak of the tracking errors,reduce adjustment time,and improve accuracy.

Ni/Co bimetallic organic frameworks nanospheres for highperformance electrochemical energy storage

In addition to their many well-known advantages(e.g.,ultra-high porosity,good pore size distribution,easy functionalization,and structural tolerability),metal-organic frameworks(MOFs)are a new class of advanced functional materials.However,their backbones are highly susceptible to deformation after exposure to acidic or alkaline conditions.As a result of lithium-ion batteries embedding or detaching directly from MOFs,they irreversibly collapse.As a result,they fail to maintain their electrochemical performance.These factors have hindered the development of MOFs as direct electrode materials,making the design of MOF materials with controlled morphology and stable dimensions a new challenge.In this study,we adopted a versatile and effective method to synthesize a novel MOF material(NiCo-BP(BP=BTC/phen and BTC=1,3,5-benzenetricarboxylic acid))using the rigid ligands 1,10-phenanthroline and homobenzotrizoic acid,and the emergence of the Ni-O/N and Co-O/N coordination layers was observed by extended X-ray absorption fine structure(EXAFS)tests,indicating that Ni and Co were coordinated with heterocyclic N-given atoms to form a stable p-πconjugated structure.Meanwhile,the metal-ion is attached to the carboxylic acid ligand on the other side,making the metal-organic skeleton complete and robust.The nanosphere structure of NiCo-BP(~400 nm)allows for full exposure and utilisation of the active sites,especially the Ni,Co,and phenanthroline units,and exhibit impressively high specific capacity and cycling stability.At a high current density of 1.0 A·g^(−1),a high discharge specific capacity of 631.6 mAh·g^(−1)was obtained after 1000 cycles.The co-participation of two organic ligands in the coordination is in accordance with the theory of soft and hard acids and bases,which contributes to the ability of the material to maintain a high capacity in cycling as well as its cyclic stability.

Bimetallic CoNiSe_(2)/C nanosphere anodes derived from Ni-Co-metal-organic framework precursor towards higher lithium storage capacity

Through uncomplicated carbonation process,a carbon-embedded CoNiSe_(2)/C nanosphere was synthesized from Ni-Co-MOF (metal-organic framework) precursor whose controllable structure and synergistic effect of bimetallic Ni/Co brought CoNiSe_(2)/C anodes with high specific surface area (172.79 m^(2)/g) and outstanding electrochemical performance.CoNiSe_(2)/C anodes obtained reversible discharge capacities of850.9 mAh/g at 0.1 A/g after cycling for 100 cycles.In addition,CoNiSe_(2)/C exhibits excellent cycle stability and reversibility in the rate test at a current density of 0.1–2.0 A/g.When the current density returns to 0.5 A/g for 150 cycles,its discharge ratio the capacity is 330.8 m Ah/g.Electrochemical impedance spectroscopy (EIS) tests suggested that CoNiSe_(2)/C anodes had a lower charge transfer impedance of 130.02Ωafter 30 cycles.In-situ X-ray diffraction (XRD) tests confirmed the alloying mechanism of CoNiSe_(2)/C which realized higher lithium storage capacity.This work affords substantial evidence for the extension of bimetallic selenides in secondary batteries,promoting the development of bimetallic selenides in anode materials for LIBs.

Core-drilling kinematic modeling and analysis of Jiaolong submersible manipulator

The complicated topographies of the deep sea pose significant challenges for the core drilling with the Jiaolong submersible manipulator.To address this problem,we proposed a core-drilling kinematic model and evaluated the core-drilling behavior of the submersible manipulator by comprehensively considering the uncertain posture of the Jiaolong submersible.First,we established a forward kinematic model for the core-drilling task in deep sea,which satisfied the requirement of gravitational-direction core drilling.Based on the forward kinematic equations,we then built a double-redundancy inverse kinematic model,which was able to determine the required motion trajectories of six active joints according to the desired core-drilling trajectory.The core-drilling workspaces and the motions of the Jiaolong submersible manipulator were assessed with several calculation examples.The established forward and inverse kinematic models are constructed with clear analytic equations,and thus are directly applicable to the Jiaolong submersible manipulator-based core-drilling task.

Microstructure and mechanical properties of Mg-Gd-Y-Sm-Al alloy and analysis of grain refinement and strengthening mechanism

The effects of Sm on the microstructure and mechanical properties of Mg-11 Gd-2 Y-0.6 Al alloy were investigated by X-ray diffraction,optical microscopy,scanning electron microscopy,energy dispersive spectrometry and high resolution transmission electron microscopy.Based on the theory of edge—edge matching and electronegativity theory,the mechanism of grain refinement is discussed.The strengthening mechanism is expounded conveniently from fine grain strengthening,coherent strengthening,precipitation strengthening and grain boundary strengthening.The results show that the micro structure of Mg-11 Gd-2 Y-0.6 Al alloy is mainly composed of a-Mg matrix,Mg5 Gd and Mg24Y5 phases.The addition of Sm forms Mg41Sm5 phase in the alloy and refines the alloy.The addition of Sm significantly improves the mechanical properties of the alloy at room and high temperatures.When the addition of Sm is 3 wt%,the tensile strengths of the alloy at room temperature and high temperature(200℃)reach the maximum value 292 and 321 MPa,respectively.The fracture mode of the alloy at different temperatures is mainly brittle fracture and intercrystalline fracture.

Review on the recent development of Li_(3)VO_(4)as anode materials for lithium-ion batteries

Among the various anodes,Li_(3)VO_(4)is a potential intercalation kind anode used in lithium-ion batteries(LIBs)that exhibits safer discharge voltage and higher capacity than graphite,a lower voltage plateau than Li_(4)Ti_(5)O_(12),and smaller volume difference in the Li^(+)intercalation/deintercalation process than metals and alloys.However,the comparatively low electronic conductivity,low initial coulombic efficiency(ICE)and serious capacity decay make the Li_(3)VO_(4)anode unviable when it comes to practical implementation.Therefore,this paper reviews the research progress of Li_(3)VO_(4)in recent years,mainly including the strategies of developing different synthesis methods to construct unique morphology,through coating,compositing or elemental doping to increase the ICE,electronic conductivity and the cycle constancy.Moreover,the application of Li_(3)VO_(4)anode materials in other energy storage systems is summarized.Lastly,the development prospect and challenge of Li_(3)VO_(4)anodes are discussed.

The bond evolution mechanism of covalent sulfurized carbon during electrochemical sodium storage process

The excellent energy storage performance of covalent sulfur-carbon material has gradually attracted great interest. However, in the electrochemical sodium storage process, the bond evolution mechanism remains an elusive topic. Herein, we develop a one-step annealing strategy to achieve a high covalent sulfur-carbon bridged hybrid(HCSC)utilizing phenylphosphinic acid as the carbon-source/catalyst and sodium sulfate as the sulfur-precursor/salt template, in which the sulfur mainly exists in the forms of C–S–C and C–S–S–C. Notably, most of the bridge bonds are electrochemically cleaved when the cycling voltage is lower than0.6 V versus Na/Na+, leading to the appearance of two visible redox peaks in the following cyclic voltammogram(CV) tests.The in-situ and ex-situ characterizations demonstrate that S^2- is formed in the reduction process and the carbon skeleton is concomitantly and irreversibly isomerized. Thus, the cleaved sulfur and isomerized carbon could jointly contribute to the sodium storage in 0.01–3.0 V. In a Na-S battery system, the activated HCSC in cut off voltage window of 0.6–2.8 V achieves a high reversible capacity(770 mA h g^-1 at 300 mA g^-1). This insight reveals the charge storage mechanism of sulfur-carbon bridged hybrid and provides an improved enlightenment on the interfacial chemistry of electrode materials.

Snake robots play an important role in social services and military needs

Intelligent robotic systems have gradually penetrated into the fields of social services and military reconnaissance with the rapid economic development.Snake robots,as multi-redundant bionic robots,play an indispensable and important role in public life and military needs.1 These robots have been widely favored and highly regarded by the academia and industry because of 1)their small size and flexibility,thereby easily entering small spaces for work,2)their ability to carry a variety of equipment for disaster rescue and military reconnaissance,and 3)their variety of movement modes,which can adapt to various complex terrain environments.

Corporate Social Capital and Business Model Innovation： The Mediating Role of Organizational Learning

Existing studies demonstrate that corporate social capital can not only enable a firm to gain access to heterogeneous information and resources, but may also facilitate the establishment of behavioral norms, communication models and mutual-trust platforms with stakeholders in its social network. As a result, corporate social capital drives organizational changes and has the potential to boost business model innovation. This paper recognizes organizational learning as a mediating mechanism that transforms corporate social capital into business model innovation. Using survey data collected from 164 Chinese firms, we tested the relationship between corporate social capital and business model innovation, as well as the mediating effect of organizational learning. Our findings clearly show how corporate social capital flows through organizational leaming efforts to business model innovation.

High-bandwidth nanopositioning via active control of system resonance

Typically,the achievable positioning bandwidth for piezo-actuated nanopositioners is severely limited by the first,lightly-damped resonance.To overcome this issue,a variety of open-and closed-loop control techniques that commonly combine damping and tracking actions,have been reported in literature.However,in almost all these cases,the achievable closed-loop bandwidth is still limited by the original open-loop resonant frequency of the respective positioning axis.Shifting this resonance to a higher frequency would undoubtedly result in a wider bandwidth.However,such a shift typically entails a major mechanical redesign of the nanopositioner.The integral resonant control(IRC)has been reported earlier to demonstrate the significant performance enhancement,robustness to parameter uncertainty,gua-ranteed stability and design flexibility it affords.To further exploit the IRC scheme’s capabilities,this paper presents a method of actively shifting the resonant frequency of a nanopositioner’s axis,thereby delivering a wider closed-loop positioning bandwidth when controlled with the IRC scheme.The IRC damping control is augmented with a standard integral tracking controller to improve positioning accuracy.And both damping and tracking control parameters are analytically optimized to result in a Butterworth Filter mimicking pole-placement—maximally flat passband response.Experiments are conducted on a nanopositioner’s axis with an open-loop resonance at 508 Hz.It is shown that by employing the active resonance shifting,the closed-loop positioning bandwidth is increased from 73 to 576 Hz.Consequently,the root-mean-square tracking errors for a 100 Hz triangular trajectory are reduced by 93%.