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Light-driven actuators that directly convert light into mechanical work have attracted significant attention due to their wireless advantage and ability to be easily controlled. However, a fundamental impediment to their application is that the continuous motion of light-driven flexible actuators usually requires a periodically switching light source or the coordination of other additional hardware. Here, for the first time, continuous flapping-wing motion under sunlight is realized through the utilization of a simple nanocrystalline metal polymer bilayer structure without the coordination of additional hardware. The light-driven performance can be controlled by adjusting the grain size of the upper nanocrystalline metallic layer or selecting metals with different thermodynamic parameters. The achieved highest frequency of flapping-wing motion is 4.49 Hz, which exceeds the frequency of real butterfly wings, thus informing the further development of sunlight-driven bionic flying animal robotics without external energy consumption. The flapping-wing motion has been used to realize a light-driven whirligig, a light-driven sailboat, and photoelectric energy harvesting. Furthermore, the flexible bilayer actuator features the ability to be driven by light and electricity, low-power actuation, a large deflection, fast actuation speed, long-time stability, strong design ability, and large-area facile fabrication. The bilayer film considered herein represents a simple, general, and effective strategy for preparing photoelectric-driven flexible actuators with target performances and informs the standardization and industrial application of flexible actuators in the future.

As one of the most sensitive regions to global climate change, alpine tundra in many places around the world has been undergoing dramatic changes in vegetation communities over the past few decades. Herbaceous plant species in the Changbai Mountains area have significantly expanded into tundra shrub communities over the past 30 yr. Soil microbial communities, enzyme activities, and soil nutrients are intertwined with this expansion process. In order to understand the responses of the soil microbial communities to such an expansion, we analyzed soil microbial community structures and enzyme activities in shrub tundra as well as areas with three different levels of herbaceous plant expansion. Our investigation was based on phospholipid fatty acid (PLFA) analysis and 96-well microtiter plates. The results showed that herbs have expanded greatly in the tundra, and they have become the dominant species in herbaceous plant expansion areas. There were differences for community composition and appearance among the shrub tundra and the mild expansion, moderate expansion, and severe expansion areas. Except for soil organic matter, soil nutrients were increased in herbaceous plant expansion areas, and the total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), and available phosphorus (AP) were greatest in moderate expansion areas (MOE), while soil organic matter levels were highest in the non-expanded areas (CK). The total soil PLFAs in the three levels of herbaceous plant expansion areas were significantly higher than those in the non-expanded areas, and total soil PLFAs were highest in the moderately expanded area and lowest in the severely expanded area (SEE). Bacteria increased significantly more than fungi and actinomycetes with herbaceous plant expansion. Soil hydrolase activities (β-1,4-glucosidase (βG) activity, β-1, 4-N-acetylglucosaminidase (NAG) activity, and acid phosphatase (aP) activity) were highest in MOE and lowest in the CK treatment. Soil oxidase activities (polyphenol oxidase (PPO) activities and peroxidase (PER) activities) were also highest in MOE, but they were lowest in the SEE treatment. The variations in total soil PLFAs with herbaceous plant expansion were mostly correlated with soil organic matter and available phosphorus concentrations, while soil enzyme activities were mostly correlated with the total soil nitrogen concentration. Our results suggest that herbaceous plant expansion increase the total soil PLFAs and soil enzyme activities and improved soil nutrients. However, soil microorganisms, enzyme activity, and nutrients responded differently to levels of herbaceous plant expansion. The soil conditions in mild and moderate expansion areas are more favorable than those in severe expansion areas.

The complicated nature of current wet crude oil requires a further upgrade of electrical dehydration technology that can satisfy the latest processing criteria. This study investigated the dehydration efficiency of a dispersed phase of distilled water in a continuous phase of conduction oil in electric fields created by three proposed electrodes. The electric field distribution was created and analyzed using COMSOL Multiphysics software and the level-set method. The results show that the electric fields created by our proposed electrodes can aid the dehydration process by optimizing the electric field distribution and the electropolymerization behaviors. Furthermore, the results indicate that the non-uniform fields formed by the proposed electrodes can lead to acceleration in the movement of water droplets as well as a facilitated sedimentation stage. A water film created by a copper mesh electrode can induce a droplet–interface coalescence, and the geometry of a grid electrode can promote a two-phase oil and water movement. These results could provide insights for the future design of the best electrode geometry for efficient electrocoalescence.

Vegetation is the main component of the terrestrial ecosystem and plays a key role in global climate change. Remotely sensed vegetation indices are widely used to detect vegetation trends at large scales. To understand the trends of vegetation cover, this research examined the spatial-temporal trends of global vegetation by employing the normalized difference vegetation index (NDVI) from the Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modeling and Mapping Studies (GIMMS) time series (1982–2015). Ten samples were selected to test the temporal trend of NDVI, and the results show that in arid and semi-arid regions, NDVI showed a deceasing trend, while it showed a growing trend in other regions. Mann-Kendal (MK) trend test results indicate that 83.37% of NDVI pixels exhibited positive trends and that only 16.63% showed negative trends (P < 0.05) during the period from 1982 to 2015. The increasing NDVI trends primarily occurred in tree-covered regions because of forest growth and re-growth and also because of vegetation succession after a forest disturbance. The increasing trend of the NDVI in cropland regions was primarily because of the increasing cropland area and the improvement in planting techniques. This research describes the spatial vegetation trends at a global scale over the past 30+ years, especially for different land cover types.

This project aimed to design a new type of vibration isolation mechanism with quasi-zero-stiffness (QZS) and analyze the QZS systems’ characteristics by computation and numerical simulation. First, the force–displacement and stiffness–displacement relational expressions of the QZS systems were established based on the study of system force and stiffness characteristics. Second, the nonlinear dynamic equations of the system under the excitation of harmonic force and harmonic displacement were established, and the effect of damping ratio, excitation amplitude, and nonlinear term under the transmissibility mechanism system was analyzed by the average method. Finally, the response time and stability of the QZS vibration isolator were analyzed under different circumstances through numerical simulation. The excitation amplitude, damping ratio, and nonlinear term have a great influence on the transmissibility of the system. In addition, under three different working conditions, the mechanism can have good vibration isolation characteristics and can meet the requirement of low-frequency vibration isolation. A novel type of the QZS systems has been investigated, and it is found that the influence of the excitation amplitude and the nonlinear term are just the same on the system transmissibility through the statics and dynamics calculations. Meanwhile, when damping ratio was increased, the transmissibility of the QZS systems could be reduced. The numerical simulations show that the system has faster response and smaller amplitude for sine wave, single shock, and multi-frequency excitations, which is more suitable for low-frequency vibration isolation.

Actuating materials can convert external stimuli (humidity, light, electricity, etc.) into mechanical energy and realize multiple forms of movements. However, a majority of current actuating materials are driven by a single stimulus with a small degree of actuation and rough control which is unfavorable for practical applications. Here, a new type of bidirectional actuating material based on carbon nanotube/PDMS composites and chitosan films is proposed. Thanks to the robust mechanical support by PDMS, due to the ultra-large water capacity in between chitosan chains and strong near-infrared light absorption by carbon nanotube layers, the actuator can be driven by humidity and light for an ultra-large actuation curvature (3.91 cm-1 in humidity actuation, 3.84 cm-1 in light actuation). The well-established light power-curvature, relative humidity-curvature profiles and a fine mechanic modelling of the actuator show the possibility of controlling the actuator's bending. A lab application as a cargo-moving device preliminarily demonstrates a robust mechanical functionality of this actuator with a low body weight.

Vegetation in high altitude areas normally exhibits the strongest response to global warming. We investigated the tundra vegetation on the Changbai Mountains and revealed the similarities and differences between the north and the southwest slopes of the Changbai Mountains in response to global warming. Our results were as follows: 1) The average temperatures in the growing season have increased from 1981 to 2015, the climate tendency rate was 0.38°C/10yr, and there was no obvious change in precipitation observed. 2) The tundra vegetation of the Changbai Mountains has changed significantly over the last 30 years. Specifically, herbaceous plants have invaded into the tundra zone, and the proportion of herbaceous plants was larger than that of shrubs. Shrub tundra was transforming into shrub-grass tundra. 3) The tundra vegetation in the north and southwest slopes of the Changbai Mountains responded differently to global warming. The southwest slope showed a significantly higher degree of invasion from herbaceous plants and exhibited greater vegetation change than the north slope. 4) The species diversity of plant communities on the tundra zone of the north slope changed unimodally with altitude, while that on the tundra zone of the southwest slope decreased monotonously with altitude. Differences in the degree of invasion from herbaceous plants resulted in differences in species diversity patterns between the north and southwest slopes. Differences in local microclimate, plant community successional stage and soil fertility resulted in differential responses of tundra vegetation to global warming.

To realize the efficient current-induced spin-orbit torque (SOT) magnetization switching, the understanding of spin source with unique physics for the charge-to-spin conversion is very important. Here, we demonstrate the current-induced SOT magnetization switching by considering non-collinear spin moments mixed by Rashba-like Sy, Dresselhaus-like Sx, and out-of-plane like Sz by using micromagnetic simulation. The magnetization switching with considering three configurations of out-of-plane magnetization (along the z-direction), in-plane magnetization along the x and y-direction have been studied. The current induced out-of-plane spin moment can effectively contribute unconventional out-of-plane damping like torque to switch the mz at zero magnetic field. Similarly, the current induced Dresselhaus-like spin moments can switch mx effectively. Our results may provide a new degree of freedom for the understanding of current-induced SOT magnetization switching by non-collinear spin source for the potential application of spintronics devices.

This paper performs a optimization research for delta shape rotor topology in interior permanent magnet synchronous motor (IPMSM). The permanent magnet (PM)arrangement, pole-arc coefficient and the angle between two main PMs are mains influence factors of IPMSM performance. This paper based on a delta shape 72s12p IMPSM model and applied Taguchi method to optimized the efficiency, average operating torque (AOT)and torque ripple proportion. Finite element method and performance simulation were carried out by using ANSOFT. A prototype was fabricated and verfied experiment was carried out. The results show that by using the Taguchi method the performance have been effectively improved.

The synapses are essential to the brain neuromorphic system, and especially the plasticity of synapse contributes significantly in cognitive functions. Ferroelectric tunnel junction (FTJ) can be utilized to emulate the synaptic functions by the effective control of resistance state, which is related with the ferroelectric polarization state of barrier layer. Here, we study the emulation of a synaptic response in the fabricated organic ferroelectric tunnel junctions (OFTJs) with Polyvinylidene fluoride (PVDF) polymer barriers. The functions of long-term potentiation and long-term depression are demonstrated by exploring the relationship between resistance and polarizing pulse. In addition, our device can be also utilized to realize multi-memory function, a device with six-resistance states is demonstrated. Our results may provide a new degree of freedom for the realization of synaptic functions in OFTJs.

Light environment significantly impacts the effectiveness of fish population restoration in developed watersheds, subserving fish passage reconstruction in hydraulic complex and habitat rehabilitation. To develop an interior connection between light-related fish response from the laboratory and field fish conservation practice, we employed a new indexing system, consisting of phototaxis rate, relative swimming speed (RSS), and optic evasion coefficient (OEC), to quantify the light-induced behaviors in Ptychobarbus kaznakovi, a representative rare cyprinid in Tibet, China, at four experimental illuminance levels (15 lx, 30 lx, 60 lx, 120 lx) and four wavelengths (red, yellow, green, blue). The fish showed negative phototaxis at all given illuminances and wavelengths. Under red light, the OEC increased significantly from 0.642 at 15 lx to 0.782 at 30 lx (P = 0.029), while the RSS decreased significantly from 3.752 to 2.383 (P

The melt flow stability has a direct effect on crystal quality during the horizontal ribbon growth (HRG) process. The mixed convection in the HRG system includes thermocapillary convection, buoyancy convection, and the convection induced by the lid-driven boundary. In this study, the influences of relevant parameters such as Marangoni number, Rayleigh number, Biot number, and horizontal motion of the ribbon on flow and temperature fields have been analyzed using computational fluid dynamics. A thermal-fluid numerical model was developed by solving the Navier–Stokes and energy equations to obtain the flow, pressure, and temperature fields. The horizontal motion of the ribbon was assumed the lid-driven boundary. The results showed that the magnitude of the Marangoni number played a decisive role in the flow and temperature distribution inside the melt. In the case of a small Marangoni number, the increase in horizontal motion velocity of the ribbon was the main factor to induce convection in the melt, and the internal temperature distribution was carried out in a heat conduction mode. With the increasing Marangoni number, the thermocapillary convection was enhanced, and the convection induced by the ribbon motion was overwhelmed by the thermocapillary effect. Moreover, the increase in Biot number could reduce the temperature nonlinearity of the free surface. Particularly, the free surface temperature begins to oscillate as the Marangoni number is increased above a threshold. A larger Marangoni number could easily result in a temperature oscillation with a larger amplitude. The results indicated that the thermocapillary effect was more sensitive to temperature and flow oscillations, and should receive more attention.

This paper proposes a new QZS joint actuator, which uses a torsion electromagnetic spring (TES) that can generate negative stiffness in parallel with a flexible rod with positive stiffness to obtain QZS characteristics with high static and low motion. In this paper, the expression of TES magnetic moment and stiffness is obtained by static analysis, the simulation is carried out by ANSYS Maxwell finite element software and the effect of TES structure parameters and current on its negative stiffness characteristics is analyzed. Then the dynamic model of QZS joint actuator is established, and the amplitude-frequency response function and torque transmissibility analytical expression are obtained by harmonic balance method, the good vibration isolation performance of QZS joint actuator is revealed. Finally, the stiffness and vibration isolation performance experiments are carried out with the QZS joint actuator to verify the correctness of the theoretical analysis, which indicates that it has a wide range of application background and research significance.

Electrocoalescence is an energy-efficient and environmentally-friendly process for breaking water-in-oil emulsions. It has been used extensively in the oil and petroleum industries. In this study, the electrocoalescence process of nanoparticle/surfactant-stabilized water droplets with a planar interface in the presence of non-uniform electric fields was experimentally investigated. The effects of electric field patterns (i.e. uniform and non-uniform fields) and nanoparticles (i.e. concentrations) on the drop-interface electrocoalescence process were systematically examined, analyzed, and discussed. The results showed that the presence of Sodium Dodecyl Sulfate (SDS) significantly increased the volume of secondary droplets and led to the apex disintegration of the main secondary droplet because of the low surface tension. At high SiO2 concentrations, the liquid bridge between the droplet and interface was difficult to form, and the whipping filament regime, sheet breakup regime, and varicose jet breakup regime, were observed, which were determined by the accumulating surface charge. In addition, three types of non-uniform fields induced by different geometrical electrode configurations, i.e. grid electrodes, mesh electrodes, and coupled electrodes, were proposed and the electric field distributions were calculated in COMSOL Multiphysics. With increasing SiO2 concentrations, coupled electrodes produced much smaller detached droplet volumes than those of pairwise mesh and grid electrodes, which was helpful to complete the coalescence of the drop and interface. Furthermore, flat electrodes, which induced a uniform electric field, produced much larger secondary droplet volumes than those of the electrodes generating non-uniform electric fields. In summary, the utilization of coupled electrodes had a positive effect on drop-interface coalescence and increased the overall separation efficiency. The outcome of this work is potentially useful in the design of compact and efficient oil-water electro-dehydration devices.

We present a novel horizontal ribbon growth (HRG) process and a theoretical analysis of this method. Assuming that the existence of the meniscus is defined by diffuse growth, we determine analytically the thickness and height of the meniscus and an explicit expression for the performance of meniscus under different conditions. We then calculate the thermal profile in melt part, as well as the conditions under which the undercooling is sufficient around the solidification point. We find that diffuse growth is more sensitive to small initial thickness, and find the minimum length of the melt part to obtain undercooling. Finally, we calculate the change rule of solidification position by a variational approach, as well as the stability of the process under different conditions. We also give an expression to the instability of past HRG methods.

In recent years, herbaceous species such as Deyeuxia angustifolia (Kom.) Y. L. Chang has invaded alpine tundra regions of the western slope of the Changbai Mountains. Because atmospheric nitrogen deposition is predicted to increase under a warming climate and D. angustifolia is sensitive to nitrogen addition, field experiments were conducted from 2010 to 2013 to determine the effect of increased nitrogen deposition on the mechanisms of D. angustifolia invasion. The goal of this study is to evaluate the impact of increased nitrogen deposition on the changes in alpine tundra vegetation (consisting mostly of Rhododendron chrysanthum Pall. and Vaccinium uliginosum Linn.). The results showed that: 1) simulated nitrogen deposition affected overall characteristics and structure of R. chrysanthum and V. uliginosum communities and had a positive impact on the growth of tundra vegetation invaded by D. angustifolia; 2) R. chrysanthum was more resistant to invasion by D. angustifolia than V. uliginosum; 3) simulated nitrogen deposition could improve the growth and enhance the competitiveness of D. angustifolia, which was gradually replacing R. chrysanthum and V. uliginosum and might become the dominant species in the system in future, transforming alpine tundra into alpine meadow in the Changbai Mountains.

This book chapter will discuss advancements in analog circuit design specifically for various wearable healthcare applications. There are a number of general trends that can be observed in this field, like multimodal sensing applications, which will be discussed. There will be a focus on analog circuits for some of the most relevant signal modalities including ExG, bio-impedance, and photoplethysmogram (PPG). Common circuit topologies and some recent state-of-the-art implementations for those will be discussed.

In this paper, we present a solidification growth model that primarily describes the principal components of horizontal ribbon growth process, but also discusses the interaction between fluid flow and heat transfer, crystallization dynamics, and the effects of oxygen impurity distribution in melts, particularly with respect to the morphology of the interface. The effects of the jet cooling rate, pulling speed, and transfer coefficient on solute transport were studied. The results showed that a higher jet velocity produces a sharper temperature gradient at the interface and a stronger Marangoni effect, facilitates solute transport in the silicon melt, and promotes higher oxygen concentration in crystal. The stronger Marangoni convection causes more rapid oxygen transfer in the silicon melt and a higher oxygen concentration. Solidification front increases the downward flow velocity of the eddy current as the pulling speed is increased; this leads to a decrease in solute concentration at the interface. An increase in the downward flow of the vortex confluence facilitates the reduction of solute concentration in the crystal. An increase in the upward flow of the vortex confluence will increase the concentration in the crystal. The oxygen concentration is concentrated at the top and bottom of the silicon ribbon.