Fully Superhydrophilic, Self-Floatable, and Multi-Contamination-Resistant Solar Steam Generator Inspired by Seaweed

Highly hydrophilic materials enable rapid water delivery and salt redissolution in solar-driven seawater desalination. However, the lack of independent floatability inhibits heat localization at the air/water interface. In nature, seaweeds with internal gas microvesicles can float near the sea surface to ensure photosynthesis. Here, we have developed a seaweed-inspired, independently floatable, but superhydrophilic (SIFS) solar evaporator. It needs no extra floatation support and can simultaneously achieve continuous water pumping and heat concentration. The evaporator resists salt accumulation, oil pollution, microbial corrosion, and protein adsorption. Densely packed hollow glass microbeads promote intrinsic floatability and heat insulation. Superhydrophilic zwitterionic sulfobetaine hydrogel provides a continuous water supply, redissolves the deposited salt, and endows the SIFS evaporator with excellent anti-fouling properties. With its unprecedented anti-contamination ability, this SIFS evaporator is expected to open a new avenue for designing floatable superhydrophilic materials and solving real-world issues of solar steam generation in complex environmental conditions.

Three-dimensional crustal density distribution beneath North China by sequential inversion of local earthquake traveltimes and gravity anomaly

A three-dimensional crustal density model beneath North China is determined using P-wave traveltimes and gravity datum by sequential inversion method in this paper. To improve the uniqueness of the solution, we used a linear relationship between velocity and density to achieve mutual conversions and constraints between velocity difference and density difference. Algebraic reconstruction technique （ART） was used in density inversion, which highly improved the calculation speed comparing with common least squares method. The inversion results indicate that the crustal density beneath North China is extremely inhomogeneous with its distribution coherent with regional tectonics. The lower crust of Taihang mountain tectonic zone shows an obvious low density characteristic. We proposed that it may be an indicator of upwelling of mantle materials or partial melting of lowermost crust.

软件工程专业物联网及嵌入式系统方向教学研究（英文）

当前,软件工程专业如何适应物联网及嵌入式系统领域的巨大需求,是一个亟待解决的问题。基于该问题,本文提出一个新方法进行该专业的课程安排及学习计划。首先,结合物联网基础设施技术,在软件工程教学中融入物联网及嵌入式系统的教学内容,分析学生惧怕物联网及嵌入式系统发展的原因;然后,提出循序渐进的由低级别嵌入式系统开发到高级别应用软件开发的学习路径;最后,分别剖析物联网及嵌入式系统方向的就业选择和职业规划。

Smart Manipulation of Gas Bubbles in Harsh Environments Via a Fluorinert-Infused Shape-Gradient Slippery Surface

Fundamental research and practical applications have examined the manipulation of gas bubbles on open surfaces in lowsurface-tension,high-pressure,and high-acidity,-alkalinity,or-salinity environments.However,to the best of our knowledge,effi cient and general approaches to achieve the smart manipulation of gas bubbles in these harsh environments are limited.Herein,a Fluorinert-infused shape-gradient slippery surface(FSSS)that could eff ectively regulate the behavior of gas bubbles in harsh environments was successfully fabricated.The unique capability of FSSS was mainly attributed to the properties of Fluorinert,which include chemical inertness and incompressibility.The shape-gradient morphology of FSSS could induce asymmetric driving forces to move gas bubbles directionally on open surfaces.Factors infl uencing gas bubble transport on FSSS,such as the apex angle of the slippery surface and the surface tension of the aqueous environment,were carefully investigated,and large apex angles were found to result in large initial transport velocities and short transport distances.Lowering the surface tension of the aqueous environment is unfavorable to bubble transport.Nevertheless,FSSS could transport gas bubbles in aqueous environments with surface tensions as low as 28.5±0.1 mN/m,which is lower than that of many organic solvents(e.g.,formamide,ethylene glycol,and dimethylformamide).In addition,FSSS could also realize the facile manipulation of gas bubbles in various aqueous environments,e.g.,high pressure(~6.8 atm),high acidity(1 mol/L H 2 SO 4),high alkalinity(1 mol/L NaOH),and high salinity(1 mol/L NaCl).The current fi ndings provide a source of knowledge and inspiration for studies on bubble-related interfacial phenomena and contribute to scientifi c and technological developments for controllable bubble manipulation in harsh environments.

Weighted Self-Adaptive Threshold Wavelets for Interpolation Point Selection Used in Interconnect MOR

As process technology development,model order reduction( MOR) has been regarded as a useful tool in analysis of on-chip interconnects. We propose a weighted self-adaptive threshold wavelet interpolation MOR method on account of Krylov subspace techniques. The interpolation points are selected by Haar wavelet using weighted self-adaptive threshold methods dynamically. Through the analyses of different types of circuits in very large scale integration( VLSI),the results show that the method proposed in this paper can be more accurate and efficient than Krylov subspace method of multi-shift expansion point using Haar wavelet that are no weighted self-adaptive threshold application in interest frequency range,and more accurate than Krylov subspace method of multi-shift expansion point based on the uniform interpolation point.

Distributed attitude consensus of spacecraft formation flying

The consensus problem of the distributed attitude synchronization in the spacecraft formation flying is considered.Firstly,the attitude dynamics of a rigid body spacecraft is described by modified Rodriguez parameters（MRPs）.Then global stable distributed cooperative attitude control laws are proposed for different cases.In the first case,the control law guarantees the state consensus during the attitude synchronization.In the second case,the control law ensures both the attitudes synchronizing to a desired constant attitude and the angular velocities converging at zero.In the third case,an attitude consensus control law with bounded control input is proposed.Finally,the effectiveness and validity of the control laws are demonstrated by simulations of six rigid bodies formation flying.

Pre-seismic gravity anomalies before Linkou Ms6.4 earthquake by continuous gravity observation of Crustal Movement Observation Network of China

A Ms6.4 earthquake occurred at Linkou country, Heilongjiang Province （44.8°N, 129.9°E） on January 2, 2016 at a depth of 580 km. Pre-seismic graviW anomalies obtained at a 1 Hz sampling rate from Crustal Movement Observation Network of China （CMONOC） are analyzed after the earthquake. The results show that： （1） different from previous studies, both pre-seismic amplitude perturbation and co-seismic amplitude perturbation are not critical inversely proportional to epicentral distance; （2） unlike shallow earthquake, the pre-seismic and co-seismic amplitude perturbation of gravity illustrate syn- chronous spatial variation characters with decrease of epicentral distance for Linkou earthquake. This may because Linkou earthquake is a deep earthquake and occurred in Pacific Plate subduction zone; （3） compared to basement and semi-basement, cave can provide a better observation environment for gPhone gravimeter to detect pre-seismic gravity anomalies.

Econometric analysis of the impacts of climate change on the livestock production in Qinghai Province

This study aims to investigate the effect of the impact mechanism of climate change on the livestock production at small watershed level and county level with the Multi-level Model(MLM)in Qinghai Province.The result indicated that the gross livestock output value was greatly influenced by the climatic factors of the small watershed level.Higher temperature promoted also by the increase of precipitation,relative humidity and sunshine duration was found to be beneficial to the development of livestock production,except in some areas where temperature rise restrained the development of local livestock production to some degree when exceeding a certain level;besides,the impact of the socioeconomic factors on the livestock output value is obvious at the county level.The gross economic output measured with GDP has some inhibitory effects on the reinvestment of livestock production,while population growth promotes development of livestock production to some degree.The results not only provide scientific basis for the management of livestock production in Qinghai Province,but also provide reference for formulating the policies and adaptation measures targeted at climate change to promote the sustainable development of livestock production in other regions.

Three-dimensional lithospheric density distribution of China and surrounding regions

In this paper, we analyze lithospheric density distribution of China and surrounding regions on the basis of 30＇ × 30＇ gravity data and 1°×1 °P-wave velodty data, Firstly, we used the empirical equation be- tween the density and the P-wave velocity difference as the base of the initial model of the Asian lithospheric density. Secondly, we calculated the gravity anomaly, caused by the Moho discontinuity and the sedimentary layer discontinuity, by the Parker formula. Thirdly, the gravity anomaly of the spherical harmonics with 2 40 order for the anomalous body below the lithosphere is calculated based on the model of EGM96. Finally, by using Algebra Reconstruction Techniques （ART）, the inversion of 30＇ ~ 30＇ residual lithospheric Bouguer gravity anomaly caused by the lithosphere yields a rather detailed struc- tural model. The results show that the lithospheric density distribution of China and surrounding regions has a certain connection with the tectonic structure. The density is relatively high in the Philippine Sea plate, Japan Sea, the Indian plate, the Kazakhstan shield and the Western Siberia plain, whereas the Tibetan Plateau has low-density characteristics. The minimum value of density lies in the north of Philippines, in the Taiwan province and in the Ryukyu island arc.

Application of robotic-assisted endoscopic third ventriculostomy

Objective:This case series study explored the application of ROSA(robot of stereotactic assistant)robotic-assisted endoscopic third ventriculostomy(ETV)in the treatment of hydrocephalus.Methods:Three patients(January2016-October2017)diagnosed with hydrocephalus based on preoperative computed tomograph(CT)and magnetic resonance imaging(MRI)scans were recruited.Navigation planning scan was performed before operation.ROSA robot localization program was used to simulate and analyze the path planning of hydrocephalus ETV and store it in the system.All the three patients underwent robotic-assisted ETV.The patients'clinical symptoms,imaging manifestations and related complications were evaluated,and a3-month follow-up survey was conducted.Prognostic factors were also analyzed.Results:ETV under the guidance of ROSA robot was successfully performed on the three patients.CT,MRI and cerebrospinal fluid(CSF)cine showed that the ventricles were narrowed,that the velocity and flow of the stoma were normal,and that the CSF flow was smooth.After discharge,the symptoms of hydrocephalus were significantly improved.Localization of the robot and design of the surgical path were key to success of the operation.Conclusions:ROSA robotic-assisted ETV is a feasible procedure.The patients recovered well,and the symptoms relieved.More efforts are needed to optimize artificial intelligence and the application of precision treatment in the nervous system.

国民国家与近代日本宪政之路——以自由民权运动为中心

作为后发型现代化国家的典型,日本在西方压力下开国15年后进行了政治变革,建立了有志于现代化的明治新政权,又在20年之后实施了宪政体制,初步完成了国民国家的内部构建。国民国家对内争取民权、对外争取国权,两者相辅相成。明治政权成立不久后,板垣退助等人组织政治团体,批判政府专制,要求制定宪法,开设国会,发动民众,开展轰轰烈烈的自由民权运动。无论是'国民国家论'还是'抗争政治',均强调了以宪政体制为中心的国民主权在近代国民国家形成过程中的核心作用。从此视角看,自由民权运动是为形成国民国家的政治文化运动。

日本近代国民意识的形成

明治时代,建立以天皇为核心的宪政制度的意识是日本精英的主流意识,存在宫中集体的"专制君主"与政府的"立宪君主"之间的对立,"立宪君主"占上风。近代日本建立的以天皇为核心的宪政制度,把天皇塑造为近代国家的象征,通过向民众灌输"忠君爱国"意识,培育出国家的奉献者,这一社会形态在日本迅速发展为世界强国的过程中发挥了较大的推动作用。但是,这也导致国民易于盲目服从,当国家出现方向性决策失误时,民众疯狂地为天皇所代表的国家献身,最终结局是国破家亡。

A Distributed Reactive Power Sharing Approach in Microgrids with Improved Droop Control

Conventional droop control causes frequency and voltage deviations(from rated value)in a inverter-intensive microgrid(MG),and the reactive power sharing cannot be obtained when the communication structure of the MG or load suddenly changes.Compared with a centralized control and droop control scheme,a distributed hierarchical control structure of the MG can overcome the limitation of communication and realize reactive power sharing.In this paper,an improved droop control is adopted,which is based on the hierarchical control structure.The hierarchical control structure consists of zerolevel control,primary control and a proposed secondary control.First,the secondary controller is modeled,and the MG system composed of distributed generators(DGs)is considered as a multi-agent system.The secondary controller can make up for the shortcomings of the droop controller and adjust the frequency and voltage to their rated values.Secondly,the reference voltage and frequency of the zero-level control are calculated,and combined with the primary control.The zero-level control and primary control can make the voltage and frequency of the MG run stably and provide reference voltage for the inverter.Finally,the stability of the system is proved by the theory of multi-agent consistency.A simulation system is established in the Matlab/Simulink environment,and the results show the effectiveness of the proposed controller.

A Finite-time Distributed Cooperative Control Approach for Microgrids

Reactive power sharing cannot be achieved using many existing microgrid(MG)control methods,but the convergence speed of these methods is slow.To solve these problems,a finite-time distributed control approach is proposed in this paper,which is based on the hierarchical control structure.The hierarchical control structure consists of a dual loop control,a droop control used as a primary control and a secondary control.First,the secondary controller is modeled,and the MG system composed of distributed generators(DGs)is considered as a multi-agent system.The secondary controller consists of a frequency regulator,voltage regulator and power regulator.Secondly,the adaptive virtual impedance module is established,using the output of the reactive power regulator as its input.Thirdly,a dual loop controller is combined with a primary controller and secondary controller to generate a pulse width modulation(PWM)signal to control the power and voltage of the MG.In order to reduce the fluctuation of the MG,a damping module is introduced when the structure of the system changes.Finally,the stability of the proposed control strategy is proved by the related theorems.A simulation system is established in the Matlab environment,and the simulation results show that the proposed method is effective.

Thickness properties hexagonal and temperature dependent electrical of ZrS2 thin films directly grown on boron nitride

Two-dimensional ZrS2 materials have potential for applications in nanoelectronics because of their theoretically predicted high mobility and sheet current density. Herein, we report the thickness and temperature dependent transport properties of ZrS2 multilayers that were directly deposited on hexagonal boron nitride （h-BN） by chemical vapor deposition. Hysteresis-free gate sweeping, metal- insulator transition, and T-γ （γ- 0.82-1.26） temperature dependent mobility were observed in the ZrS2 films.

Metallic and ferromagnetic MoS2 nanobelts with vertically aligned edges

Edge effects are predicted to significantly impact the properties of low dimensional materials with layered structures. The synthesis of low dimensional materials with copious edges is desired for exploring the effects of edges on the band structure and properties of these materials. Here we developed an approach for synthesizing MoS2 nanobelts terminated with vertically aligned edges by sulfurizing hydrothermally synthesized MoO3 nanobelts in the gas phase through a kinetically driven process; we then investigated the electrical and magnetic properties of these metastable materials. These edge-terminated MoS2 nanobelts were found to be metallic and ferromagnetic, and thus dramatically different from the semiconducting and nonmagnetic two-dimensional （2D） and three-dimensional （3D） 2H-MoS2 materials. The transitions in electrical and magnetic properties elucidate the fact that edges can tune the properties of low dimensional materials. The unique structure and properties of this one-dimensional （1D） MoS2 material will enable its applications in electronics, spintronics, and catalysis.

Application of endoscopic endonasal approach in skull base surgeries: summary of 1886 cases in a single center for 10 consecutive years

Background:Endonasal endoscopic skull base surgery has undergone rapid technological developments and is now widely performed,but its strengths and weaknesses deserve further investigation and deliberation.This study was performed to investigate the surgical indications,complications,and technical advantages and disadvantages of endonasal endoscopic skull base surgery.Methods:The clinical data of 1886 endoscopic endonasal skull base surgeries performed in our ward at Beijing Tiantan Hospital from June 2006 to June 2016 were retrospectively analyzed.Results:One thousand ninety-three(73.4%,1490)pituitary adenomas,54(24.9%,217)chordomas,28(80.0%,35)craniopharyngiomas,and 15(83.3%,18)meningiomas underwent total resection.Two patients died postoperatively,both having pituitary adenomas.Other postoperative complications included olfactory disorders(n=226,11.9%),postoperative cerebrospinal fluid leakage(n=78,4.1%),hypopituitarism(n=74,3.9%),diabetes insipidus(n=64,3.4%),intracranial infection(n=36,1.9%),epistaxis(n=24,1.3%),vascular injury(n=8,0.4%),optic nerve injury(n=8,0.4%),and oculomotor movement impairment(n=4,0.2%).In total,1517(80.4%)patients were followed up for 6 to 126 months(average,42.5 months)postoperatively.A total of 196(13.2%)pituitary adenomas and 13(37.1%)craniopharyngiomas recurred but no meningiomas recurred.Chordomas recurred in 97(44.7%)patients,in whom 5-year survival rate was 65%.Conclusion:Endoscopic surgery is an innovative surgical technique and the first choice for most midline extradural lesions such as chordomas,and an excellent choice for pituitary adenomas.It probably will be a good technique for many kinds of craniopharyngiomas and a common technique for most of skull base meningiomas,so the surgical indications of these cases should be chosen carefully to make good use of its respective advantages.

Layer-dependent charge density wave phase transition stiffness in 1T-TaS_(2)nanoflakes evidenced by ultrafast carrier dynamics

Novel physical properties emerge when the thickness of charge density wave(CDW)materials is reduced to the atomic level,owing to the significant modification of the electronic band structure and correlation effects.Here,we investigate the layer-dependent CDW phase transition and evolution of the nonequilibrium state of 1T-TaS_(2)nanoflakes using pump-probe spectroscopy.Both the low-energy single-particle and collective excitation relaxations exhibit sharp changes at〜210 K,indicating a phase transition from commensurate CDW to nearly commensurate CDW state.The single particle process reveals that the phase transition stiffness(PTS)is thickness-dependent.Moreover,a small PTS is observed in thin nanoflakes,which is attributed to the reduced thickness that increases the fluctuation and inhibits the nucleation and growth of discommensurations.In addition,the phase mode vanishes when the discommensuration network appears.Our results suggest that the carrier dynamics could be an efficient operational approach to measuring the quantum phase transition in correlated materials.

Local Unstable Entropy and Local Unstable Pressure for Partially Hyperbolic Endomorphisms

In this paper,local unstable metric entropy,local unstable topological entropy and local unstable pressure for partially hyperbolic endomorphisms are introduced and investigated.Specially,two variational principles concerning relationships among the above mentioned numbers are formulated.

Z^(k)-作用的具有跟踪性的子系统

本文研究Z^(k)-作用子系统的跟踪性.设α是紧致度量空间X上一个连续的Z^(k)-作用.我们引入α沿着R^(k)的子集(特别是R^(k)的子空间)的伪轨及跟踪性的概念,证明了如果α沿着R^(k)的子空间V具有跟踪性并且是可扩的,则α沿着R^(k)中任意包含V的子空间W也具有跟踪性并且是可扩的.设α是闭Riemann流形M上的一个光滑Z^(k)-作用,μ是一个遍历的概率测度,Γ是相应的Oseledec集.在关于Lyapunov谱的一个基本假设下,本文证明了α在Γ上沿着R^(k)中任意包含一个正则向量的子空间V具有跟踪性并且是可扩的.进一步得到α在Γ上沿着R^(k)中任意包含一个第一型奇异向量的1维子空间V具有拟跟踪性.作为应用,本文讨论了由α诱导的扭扩流形上的R^(k)-作用的具有跟踪性的1维子系统(即流).