Periodic event-triggered dynamic output feedback control for networked control systems subject to packet dropouts.

This paper proposes a co-design method of dynamic output feedback control law and periodic event-triggered control (PETC) strategy to tolerate a maximum allowable number of successive packet dropouts (MANSDs) in networked control systems (NCSs). For the purpose of striking a balance between saving limited communication resources and reducing complexity of the transmission implementation, we present the periodic event-triggering mechanism (PETM), in which the triggering conditions only needs to be monitored at each event-verifying instant. In NCSs, packets often suffer from some interference in network transmission, such as packet losses. For packet dropouts, we introduce a dropout variable and model the whole closed-loop systems as a hybrid system. Furthermore, some stability conditions for co-design are given by a novel Lyapunov function and stability theorems of hybrid systems, and the explicit designs parameters of controller and triggering conditions are presented to ensure L2 stability. Finally, two illustrated examples are given to show the effectiveness of the proposed design methods.

Study on In-Situ Tool Wear Detection during Micro End Milling Based on Machine Vision.

Most in situ tool wear monitoring methods during micro end milling rely on signals captured from the machining process to evaluate tool wear behavior; accurate positioning in the tool wear region and direct measurement of the level of wear are difficult to achieve. In this paper, an in situ monitoring system based on machine vision is designed and established to monitor tool wear behavior in micro end milling of titanium alloy Ti6Al4V. Meanwhile, types of tool wear zones during micro end milling are discussed and analyzed to obtain indicators for evaluating wear behavior. Aiming to measure such indicators, this study proposes image processing algorithms. Furthermore, the accuracy and reliability of these algorithms are verified by processing the template image of tool wear gathered during the experiment. Finally, a micro end milling experiment is performed with the verified micro end milling tool and the main wear type of the tool is understood via in-situ tool wear detection. Analyzing the measurement results of evaluation indicators of wear behavior shows the relationship between the level of wear and varying cutting time; it also gives the main influencing reasons that cause the change in each wear evaluation indicator.

Three-Dimensional Graphene/Ag Aerogel for Durable and Stable Li Metal Anodes in Carbonate-Based Electrolytes.

The use of Li metal as the anode for Li-based batteries has attracted considerable attention due to its ultrahigh energy density. However, the formation of Li dendrites, uneven deposition, and huge volume changes hinder its reliable implementation. These issues become much more severe in commercial carbonate-based electrolytes than in ether-based electrolytes. Herein, a rationally designed three-dimensional graphene/Ag aerogel (3D G-Ag aerogel) is proposed for Li metal anodes with long cycle life in carbonate-based electrolytes. The modified lithiophilic nature of G-Ag aerogel, realized through decoration with Ag NPs, effectively decreases the energy barrier for Li nucleation, regulating uniform Li deposition behavior. Moreover, the highly flexible, conductive 3D porous architecture with hierarchical mesopores and macropores can readily accommodate deposited Li and ensures the integrity of the conductive network during cycling. Consequently, high coulombic efficiency (over 93.5 %) and a significantly long cycle life (1589 h) over 200 cycles, with a relatively high cycling capacity of 2.0 mAh cm-2 , can easily be achieved, even in a carbonate-based electrolyte. Considering the intrinsic high voltage windows of carbonate-based electrolytes, matching the G-Ag aerogel Li metal anode with a high-voltage cathode can be envisaged for the fabrication of high-energy-density Li secondary batteries.

Vinyl Ethylene Carbonate as an Effective SEI-Forming Additive in Carbonate-Based Electrolyte for Lithium-Metal Anodes.

We report the use of vinyl ethylene carbonate as a new solid electrolyte interface (SEI)-forming additive for Li-metal anodes in carbonate-based electrolyte, which has the advantages of both good storage performance and low price. Compared to the SEI formed in vinyl ethylene carbonate-free electrolyte, the SEI film formed in 10% vinyl ethylene carbonate electrolyte contains a higher relative content of polycarbonate species and a greater amount of decomposition products of LiPF6 salt. Both components are expected to have positive effects on the passivation of Li-metal surface and the accommodation of volume changes of anode during cycling. Scanning electron microscopy images and COMSOL numerical simulation results further confirm that uniform Li deposition morphology can be achieved in the presence of vinyl ethylene carbonate additive. When cycling at the current density of 0.25 mA cm-2 with a cycling capacity of 1.0 mAh cm-2, the vinyl ethylene carbonate-contained Li-Cu cell exhibits a long life span of 816 h (100 cycles) and a relatively high Coulombic efficiency of 93.2%.

Nanostructured Li3 V2 (PO4 )3 Cathodes.

To further increase the energy and power densities of lithium-ion batteries (LIBs), monoclinic Li3 V2 (PO4 )3 attracts much attention. However, the intrinsic low electrical conductivity (2.4 × 10-7 S cm-1 ) and sluggish kinetics become major drawbacks that keep Li3 V2 (PO4 )3 away from meeting its full potential in high rate performance. Recently, significant breakthroughs in electrochemical performance (e.g., rate capability and cycling stability) have been achieved by utilizing advanced nanotechnologies. The nanostructured Li3 V2 (PO4 )3 hybrid cathodes not only improve the electrical conductivity, but also provide high electrode/electrolyte contact interfaces, favorable electron and Li+ transport properties, and good accommodation of strain upon Li+ insertion/extraction. In this Review, light is shed on recent developments in the application of 0D (nanoparticles), 1D (nanowires and nanobelts), 2D (nanoplates and nanosheets), and 3D (nanospheres) Li3 V2 (PO4 )3 for high-performance LIBs, especially highlighting their synthetic strategies and promising electrochemical properties. Finally, the future prospects of nanostructured Li3 V2 (PO4 )3 cathodes are discussed.

Fe2O3/SnSSe Hexagonal Nanoplates as Lithium-Ion Batteries Anode.

Novel two-dimensional (2D) Fe2O3/SnSSe hexagonal nanoplates were prepared from hot-inject process in oil phase. The resulted hybrid manifests a typical 2D hexagonal nanoplate morphology covered with thin carbon layer. Serving as anode material of lithium-ion battery (LIB), the Fe2O3/SnSSe hybrid delivers an outstanding capacity of 919 mAh g-1 at 100 mA g-1 and a discharge capacity of 293 mAh g-1 after 300 cycles at the current density of 5 A g-1. Compared with pristine SnSSe nanoplates, the Fe2O3/SnSSe hybrid exhibits both higher capacity and better stability. The enhanced performance is mainly attributed to the 2D substrate together with the synergistic effects offered by the integration of SnSSe with Fe2O3. The 2D Fe2O3/SnSSe hybrid can afford highly accessible sites and short ion diffusion length, which facilitate the ion accessibility and improves the charge transport. The novel structure and high performance demonstrated here afford a new way for structural design and the synthesis of chalcogenides as LIB anodes.

Enhanced catalytic activity of monodispersed porous Al2O3 colloidal spheres with NiMo for simultaneous hydrodesulfurization and hydrogenation.

Novel composites made from monodispersed porous Al-glycolate spheres (NiMo/Al-SP) were synthesized through alcoholysis or hydrolysis treatments. The obtained samples were characterized by a complementary combination of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N2 physisorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H2-TPR), and pyridine Fourier transform infrared spectroscopy (Py FT-IR). In addition, the catalytic performances of the resultant catalysts were evaluated in the simultaneous HDS of dibenzothiophene (DBT) and HYD of naphthalene (DBT and naphthalene represent the sulfur-containing compounds and polycyoalkanes, respectively). The experimental results showed that, 71.22% DBT and 88.28% naphthalene were converted by NiMo/Al-SP(H) under the conditions of 270 °C temperature, 5 MPa H2 (initial pressure at room temperature) and 10 h reaction time. The design and preparation of NiMo/Al-SP provide an effective and novel pathway for the development of high-performance catalysts and production processes.

Carbon Coated SnS/SnO2 Heterostructures Wrapping on CNFs as an Improved-Performance Anode for Li-Ion Batteries: Lithiation-Induced Structural Optimization upon Cycling.

Carbon coated SnS/SnO2 heterostructures wrapping on carbon nanofibers (C@SnS/SnO2@CNFs) was demonstrated to have excellent performance as an anode material for Li-ion batteries. C@SnS/SnO2@CNFs electrode delivers high reversible capacity of 826.8 mA h g-1 (500th cycle) at the current density of 1.0 A g-1. However, an interesting phenomenon of increasing capacity on cycling can be observed. According to the analysis of the evolution of structure and electrochemical property, C@SnS/SnO2@CNFs is demonstrated to experience the progress of conversion from nanowalls containing polycrystals into amorphous nanosheets with high porosity and larger surface upon cycling. The above lithiation-induced structural optimization provides larger effective surface areas and encourages the conversion reactions, which can promote charge transfer and also enhance the reversibility of the conversion reactions of SnS and SnO2 inducing the increasing reversible capacity. The study explains the progress of increasing capacity of C@SnS/SnO2@CNFs and likewise provides a perspective on optimization of the electrochemical performance of electrodes.

In situ growth of NiCo(2)S(4) nanosheets on graphene for high-performance supercapacitors.

We demonstrate a facile hydrothermal method for growth of ultrathin NiCo2S4 nanosheets on reduced graphene oxide (RGO), which exhibit remarkable electrochemical performance with higher capacitance and longer cycle life than the bare NiCo2S4 hollow spheres (HSs).

[Study on hair Hg and Pb content distribution of traffic polices, Guilin].

95 hair samples from traffic polices and 110 hair samples from ordinary people were collected from 6 areas of Guilin, China, and Hg, Pb contents in hairs were determined. The result shows that the heavier the traffic was, the higher hair Hg, Pb contents of traffic polices are. Hair Hg, Pb contents of traffic polices also increase with their working time. Average hair Hg, Pb contents of outdoor polices are higher than those of indoor polices. The average hair Hg content (1.340 microg x g(-1)) of traffic polices is 1.74 times as high as the Chinese average value (0.77 microg x g(-1)), while the average hair Pb content (2.877 microg x g(-1)) is below the Chinese average value (6.60 microg x g(-1)). The use of unleaded petrol reduced the air Pb pollution, but Hg pollution still exists. The average hair Hg content (1.504 microg x g(-1)) in male traffic polices is higher than that (1.176 microg x g(-1)) of female traffic polices,while the average hair Pb content (2.852 microg x g(-1) in male traffic polices lower than that (2. 902 microg x g(-1)) of female traffic polices.

Small quantities of cobalt deposited on tin oxide as anode material to improve performance of lithium-ion batteries.

In this report, we present a hybrid structure involving a small quantity of Co element uniformly deposited on porous SnO(2) spheres as stable and high capacity anode materials for lithium-ion batteries. Specifically, Co element deposited on SnO(2) nanomaterials exhibited an exceptional reversible capacity of 810 mA h g(-1) after 50 cycles which is higher than the pure SnO(2) electrode. Based on the experiments results, a possible mechanism for the change of this structure during lithium ion insertion/extraction was proposed. The minute quantity of Co element uniformly deposited on SnO(2) spherical structure could prevent Sn aggregation during charging-discharging, and high porosity of the spherical structure allowed the volume expansion during lithium ion alloying/dealloying. The SnO(2) deposited with small quantities of Co element as electrode facilitated improved performance of lithium ion batteries with higher energy densities.

Synthesis of cobalt ion-based coordination polymer nanowires and their conversion into porous Co3O4 nanowires with good lithium storage properties.

Cobalt ion-based coordination polymer nanowires were synthesized by using nitrilotriacetic acid (NA) as a chelating agent by a one-step hydrothermal approach. In the synthesis, cobalt ions were bonded with amino or carboxyl groups of NA to form one-dimension polymer nanowires, which can be confirmed by FTIR and TGA results. Our experimental results show that the morphologies of polymer nanowires greatly depend on the precursor salts, ratios between deionized water and isopropyl alcohol. The probable molecular formula and growth mechanism have been proposed. After heat treatment, the cobalt ion-based coordination polymer nanowires can be converted into porous Co(3)O(4) nanowires, which completely preserved the nanowire-like morphology. When used as anodes in lithium-ion batteries, the obtained porous Co(3)O(4) nanowires exhibited a high reversible capacity of 810 mA h g(-1) and stable cyclic retention at 30th cycle. The good electrochemical performance could be attributed to the porous nanostructure of Co(3)O(4), which provides pathways for easy accessibility of electrolytes and fast transportation of lithium ions.

Electrocatalytic activity of horseradish peroxidase/chitosan/carbon microsphere microbiocomposites to hydrogen peroxide.

Colloidal carbon microspheres (CMS) are dispersed in chitosan (CHIT) solution to form an organic-inorganic hybrid with excellent micro-environment for the immobilization of biomolecules. A novel amperometric biosensor for the determination of hydrogen peroxide (H(2)O(2)) has been constructed by entrapping horseradish peroxidase (HRP) in as-synthesized CMS/CHIT hybrid. The modification of glassy carbon electrode is made by a simple solution-evaporation method. The electrochemical properties of the biosensor are characterized in electrochemical methods. The proposed biosensor shows high sensitive determination and fast response to H(2)O(2) at -0.15 V. The constructed HRP/CHIT/CMS/GC electrode also exhibits a fine linear correlation with H(2)O(2) concentration. The calculated value of the apparent Michaelis-Menten constant, 2.33 mM, suggests that the HRP in CMS/CHIT hybrid keeps its native bioactivity and has high affinity for H(2)O(2).

A novel amperometric biosensor based on NiO hollow nanospheres for biosensing glucose.

NiO hollow nanospheres were synthesized by controlled precipitation of metal ions with urea using carbon microspheres as templates, which were for the first time adopted to construct a novel amperometric glucose biosensor. Glucose oxidase was immobilized on the surface of hollow nanospheres through chitosan-assisted cross-linking technique. Due to the high specific active sites and high electrocatalytic activity of NiO hollow nanospheres, the constructed glucose biosensors exhibited a high sensitivity of 3.43 microA/mM. The low detection limit was estimated to be 47 microM (S/N=3), and the Michaelis-Menten constant was found to be 7.76 mM, indicating the high affinity of enzyme on NiO hollow nanospheres to glucose. These results show that the NiO hollow nanospheres are a promising material to construct enzyme biosensors.

Rapid and ultrahigh ethanol sensing based on Au-coated ZnO nanorods.

Rapid and ultrahigh sensing is realized from Au-coated ZnO rods with diameters down to 15 nm. Both the small diameters and the Au coating make the surface-depletion effect more pronounced for gas sensing. Such enhanced surface depletion increases the sensitivity, lowers the operation temperature and decreases the response time. A sensitivity of 89.5-100 ppm ethanol is obtained with response time shorter than 2 s at 300 °C, and the operation temperature can be as low as 150 °C. It is found that the Au coating improves the sensitivity by three times; this is much higher than that of noble metal-doped metal oxide sensors controlled by a grain-boundary barrier. Our results imply that the surface-depletion model is very helpful in fabricating high performance gas sensors.