Search

Road weather conditions are closed-related to the transportation safety and traffic capacity. With the development of road surveillance systems, weather conditions could be recognized from video. However, it is hard to be detected by machine. To address it, a deeply supervised convolution neural network (DS-CNN) is designed and trained on a self-established dataset. The traffic image dataset includes five groups labeled with “sunny”, “overcast”, “rainy”, “snowy” and “foggy”. Each group has manually labeled and selected more than 2500 images. The DS-CNN, can achieve the precision rate of 0.9681 and the recall rate of 0.9681. This practical weather detection method has been built in the surveillance system covers five freeways. The experimental result used in practice shows much worse detection results at first with disturbance of difference scenarios, worn camera, transmission failure and so on. With further improvement of DS-CNN, we found that it was much more effective than hand-crafted features in this task, and a deeper neural architecture could derive more powerful features. Moreover, the results show that dense weather information has more details in a small scale. In order to fast report the regional weather detection result, a designed visualization method is also proposed in spatiotemporal dimension to fuse with currently-used system. The high accuracy and fast detection speed with friendly visualization would lead to more precise traffic management and prompt the road weather traffic control to more intelligence levels.

Traffic congestion detection plays an important role for road management. However, it is difficult to automatically report traffic congestion when it occurs in large-scale road network. One of key challenges for rapidly and precisely identifying early congestion is huge variations in appearance caused by illumination, weather, camera settings and other traffic conditions. To address it, we proposed a traffic-oriented model to classify congestion from large dataset of ultra-low frame rate video captured from traffic surveillance system. The proposed deeply supervised traffic congestion detector has two modules: attention proposal module and deeply supervised inception network. Specifically, within the shallow layers, the binary edge/corner density features are used in attention proposal module to generate the rang of interest (ROI) mask automatically. This strategy keeps the training process focusing on the congestion features without disturbances. Following the attention proposal module, a very deep structure based on the inception network was used together to effectively extract rich and discriminative features then detect traffic congestion. The approach was tested on a self-established dataset based on empirical data, which contains images captured from 14470 surveillance cameras for monitoring 5,215 km of freeway in Shaanxi province, China. The experimental results show that the accuracy of the proposed method could reach 95.77% considering various disturbances, conditions and other limitations, which is improved than unsupervised networks.

Traffic conditions of truck flow is one of the critical factors influencing transportation safety and efficiency, which is directly related to traffic accidents, maintenance scheduling, traffic flow interruption, risk control, and management. The estimation of the truck flow of various types could be better to identify the irregular flow variation introduced by various trucks and quantitatively assessed the corresponding road risks. In this paper, the dynamics of truck flow are estimated first. The stochastic and uncertain trucks flow data are obtained in terms of small, medium, heavy, and the oversize truck type and regulated corresponding flow in the time series within five minutes. In order to dig the spatial-temporal correlations behind those data, the deep learning-based method is improved on the basis of the gated recurrent unit (GRU) to estimate the truck flow for various types. To quantitatively assess the truck-related effect for road risk, a multiple logistic regression method is further proposed to classify into safe, risky, and dangerous road risks levels. Different risk level could guide the traffic control and management and traffic information that broadcast drivers to help them to choose travel route. The proposed prediction of the road risk is tested in the randomly selected road segment and shows superior compared to other methods. This could promote road safety in the development of intelligent transport system (ITS).

Despite the huge amount of traffic surveillance videos and images have been accumulated in the daily monitoring, deep learning approaches have been underutilized in the application of traffic intelligent management and control. In this paper, traffic images, including various illumination, weather conditions, and vast scenarios, are extracted from the current surveillance system using in Shaanxi Province and preprocessed to set up a proper training dataset. In order to detect traffic congestion, a network structure is proposed based on residual learning to be pre-trained and fine-tuned. The network is then transferred to the traffic application and re-trained with self-established training dataset to generate the TrafficNet. The accuracy of TrafficNet to classify congested and uncongested road states reaches 99% for the validation dataset and 95% for the testing dataset. The proposed TrafficNet are verified by a regional detection of traffic congestion on a large-scale surveillance system currently using in China. The effectiveness and efficiencies are magnificently demonstrated with quick detection in the high accuracy in the case study. The experimental trial could extend its successful application to traffic surveillance system and has potential enhancement for intelligent transport system in future.

MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres were prepared by urea-hydrolysed hydrothermal reaction and the subsequent calcinations. The morphology and structure of the products were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscope and Fourier transformed infrared. The adsorption performance of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for the removal of an anionic dye (Congo Red, CR) from aqueous solution was investigated. The results showed that MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres are particularly efficient in removing CR. The adsorption follows a pseudo-second-order kinetic model and best fits the Langmuir isotherm model. The maximum adsorption capacities of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for CR were found to be 213.2 and 49.8 mg g−1, respectively. The both adsorption processes were found to be spontaneous and exothermic in nature.

The bowknot-like ZnFe2O4 superstructures have been synthesized by the decomposition of the zinc ferrioxalate microstructures, which are prepared by facile method at room temperature. The obtained products are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and nitrogen sorption measurements. The adsorption performances of bowknot-like ZnFe2O4 superstructures are tested with the removal of typical pollutants of Cr(VI) from simulated wastewater. The results show that the as-prepared bowknot-like ZnFe2O4 superstructures can effectively remove Cr(VI) from the wastewater. Kinetics of the Cr(VI) removal is found to follow pseudosecond-order rate equation. The adsorption isotherms of bowknot-like ZnFe2O4 superstructures can be described very well by the Langmuir equation. Therefore, the as-obtained bowknot-like ZnFe2O4 superstructures are promising absorbents for wastewater treatment.

Mesoporous NiO microspheres with the average diameters of 1.5 μm, 2 μm, 5 μm and 10 μm were successfully prepared by the direct thermal transformation of nickel oxalate microspheres as the sacrificial oxalate template, which was facilely synthesized by simple precipitation reaction with controllable size in the control of polyvinyl alcohol. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and nitrogen adsorption–desorption measurement. Specific surface area of the mesoporous NiO microspheres with the average diameters of 10 μm was calculated as 110.2 m 2 g −1 by BET method. The mesoporous NiO microspheres as adsorbents exhibited rapid adsorption rate for methyl orange and high adsorption capacity of 113.64 mg g −1 for methyl orange. Batch kinetic experiments showed that pseudo-second-order kinetic equation can better describe the adsorption kinetics, and the experimental data of equilibrium adsorption fitted very well to Langmuir model. The thermodynamic parameters of Δ G °, Δ H ° and Δ S ° showed that adsorption of methyl orange on mesoporous NiO microspheres was an exothermic and spontaneous in nature.

Three-dimensional CoFe 2 O 4 superstructures are prepared by the controlled thermal decomposition of the complex oxalate with various hierarchical nanostructures, which are obtained via poval (PVA) mediated precipitation reaction. The influence of experimental parameters including the concentration of PVA, reaction temperature, and reaction time was systematically investigated to study the possible formation mechanism of the superstructure. The as-prepared samples are characterized by X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The catalytic property of the as-prepared superstructure is also carried out. The results show that the hierarchical structure presents superior catalytic activity for ammonium perchlorate by decreasing its decomposition temperature to as low as 290 °C and more decomposition occurs at the low temperature phase (LTD) stage.

Li4Ti5−x Zn x O12 (x = 0, 0.05) anode materials were prepared by a two-step solid-state method. The structure and over-discharge property of the as-prepared materials were analyzed by x-ray diffraction (XRD), scanning electron microscopy (SEM), differential capacitance, and galvanostatic charge-discharge measurements. XRD patterns demonstrate that both samples have the phase of Li4Ti5O12 with an ordered spinel structure indexed to the cubic Fd3m space group. The lattice parameter of the Li4Ti4.95Zn0.05O12 sample is slightly smaller than that for the pure Li4Ti5O12 samples. SEM exhibits that the size of the Zn-doped Li4Ti5O12 and pure Li4Ti5O12 is about 1-1.5 μm. Charge-discharge tests show that Li4Ti4.95Zn0.05O12 exhibits excellent cycling performance and higher discharge capacity than those of Li4Ti5O12 even at different charge-discharge rates. The differential capacitance curves confirm that the zinc doping is beneficial to the reversible intercalation and de-intercalation of Li+.

Lithium ion batteries have become attractive for portable devices due to their higher energy density compared to other systems. With a growing interest to develop rechargeable batteries for electric vehicles, lithium iron phosphate (LiFePO4) is considered to replace the currently used LiCoO2 cathodes in lithium ion cells. LiFePO4 is a technically important cathode material for new-generation power lithium ion battery applications because of its abundance in raw materials, environmental friendliness, perfect cycling performance, and safety characteristics. However, the commercial use of LiFePO4 cathode material has been hindered to date by their low electronic conductivity. This review highlights the recent progress in improving and understanding the electrochemical performance like the rate ability and cycling performance of LiFePO4 cathode. This review sums up some important researches related to LiFePO4 cathode material, including doping and coating on surface. Doping elements with coating conductive film is an effective way to improve its rate ability.

Magnetic γ-Fe 2 O 3 /activated carbon microspheres have been synthesized by an activation process of carbon microspheres containing iron oxides, which were prepared by hydrothermal method. The structure and morphology of the magnetic porous carbon microspheres were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), thermogravimetry and differential thermal analysis (TG-DTA) and N 2 adsorption–desorption technique. The results showed that the as-prepared activated carbon spheres were the composite of single-phase γ-Fe 2 O 3 and activated carbon material, and the content of carbon was about 3.87%. Using methyl orange as model pollutant, the magnetic porous carbon microspheres showed good adsorption capacities of 44.65 mg/g. The isotherm evaluations revealed that the Langmuir model attained better fits to the experimental equilibrium data than the Freundlich model. These magnetic porous carbon microspheres could potentially be applied in separation processes.

LiMn2O4 has been considered a promising cathode material for lithium-ion batteries in electric vehicles. However, there are still a number of problems of severe capacity fading before any materials modifications. Among all doped LiMn2O4, spinel LiNi0.5Mn1.5O4 material is seen as a potential cathode material for use in electric vehicles and energy storage systems in the future because of its high working potential (4.7 V), high energy density (the energy density of LiNi0.5Mn1.5O4 is 20% higher than that of LiCoO2), acceptable stability, and good cycling performance. In the presented paper, the structure and electrochemical performance of doped LiNi0.5Mn1.5O4 are reviewed. The rate capability, rate performance and cyclic life of various doped LiNi0.5Mn1.5O4 materials are described. This review also focuses on the present status of doped LiNi0.5Mn1.5O4, then on its near future developments.

LiFePO4-positive electrode material was successfully synthesized by a solid-state method, and the effect of storage temperatures on kinetics of lithium-ion insertion for LiFePO4-positive electrode material was investigated by electrochemical impedance spectroscopy. The charge-transfer resistance of LiFePO4 electrode decreases with increasing the storage temperatures. This suggests that it has a high electrochemical activity at high temperature. The diffusion coefficient of lithium ion is greatly increased with increasing the storage temperatures, indicating that the kinetics of Li+ and electron transfer into the electrodes were much fast at high storage temperature.

The electronic property and structural stability of LiMn2O4 and LiNi0.5Mn1.5O4 with Fd 3 ¯ m space group are investigated by density functional theory (DFT) plane-wave pseudopotential method. The calculated values of Mn(Ni)–O bond lengths are found to be consistent with the reported experimental values. Due to the Ni doping, the significant shortening of Mn(Ni)–O bond strengthens the structural stability of spinel. The electronic properties of spinel show that the bonding between O and metal (Mn and Ni) is also strengthened due to the Ni doping, and then it improves the structural stability of LiNi0.5Mn1.5O4. Ni-doped spinel has a lower formation enthalpy than that of the pristine, indicating that the Ni doping improves the structural stability of spinel.

Lithium-ion batteries with both high power and high energy density are one of the promising power sources for electric devices, especially for electric vehicles (EV) and other portable electric devices. One of the challenges is to improve the safety and electrochemical performance of lithium ion batteries anode materials. Li 4 Ti 5 O 12 has been accepted as a novel anode material of power lithium ion battery instead of carbon because it can release lithium ions repeatedly for recharging and quickly for high current. However, Li 4 Ti 5 O 12 has an insulating character due to the electronic structure characterized by empty Ti 3d-states, and this might result in the insufficient applications of LTO at high current discharge rate before any materials modifications. This review focuses first on the present status of Li 4 Ti 5 O 12 including the synthesized method, doping, surface modification, application and theoretical calculation, then on its near future development.

The effect of Li 4 Ti 5 O 12 (LTO) coating amount on the electrochemical cycling behavior of the LiCoO 2 cathode was investigated at the high upper voltage limit of 4.5 V. Li 4 Ti 5 O 12 (≤5 wt.%) is not incorporated into the host structure and leads to formation of uniform coating. The cycling performance of LiCoO 2 cathode is related with the amount of Li 4 Ti 5 O 12 coating. The initial capacity of the LTO-coated LiCoO 2 decreased with increasing Li 4 Ti 5 O 12 coating amount but showed enhanced cycling properties, compared to those of pristine material. The 3 wt.% LTO-coated LiCoO 2 has the best electrochemical performance, showing capacity retention of 97.3% between 2.5 V and 4.3 V and 85.1% between 2.5 V and 4.5 V after 40 cycles. The coulomb efficiency shows that the surface coating of Li 4 Ti 5 O 12 is beneficial to the reversible intercalation/de-intercalation of Li + . LTO-coated LiCoO 2 provides good prospects for practical application of lithium secondary batteries free from safety issues.

Spinel LiMn 2 O 4 and LiMn 1.4 Cr 0.2 Ni 0.4 O 4 cathode materials were successfully synthesized by the citric-acid-assisted sol–gel method with ultrasonic irradiation stirring. The structure and electrochemical performance of the as-prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectrometer, cyclic voltamogram (CV) and the galvanostatic charge–discharge test in detail. XRD shows that all the samples have high phase purity, and the powders are well crystallized. SEM exhibits that LiMn 1.4 Cr 0.2 Ni 0.4 O 4 has more uniform cubic-structure morphology than that of LiMn 2 O 4 . EDX reveals that a small amount of Mn 3+ still exists in LiMn 1.4 Cr 0.2 Ni 0.4 O 4 . The galvanostatic charge–discharge test indicates that the initial discharge capacities for the LiMn 1.4 Cr 0.2 Ni 0.4 O 4 and LiMn 2 O 4 at 0.15 C discharge rates are 130.8 and 130.2 mAh g −1 , respectively. After 50 cycles, their capacity are 94.1% and 85.1%, respectively. The CV curve implies that Ni and Cr dual substitutions are beneficial to the reversible intercalation and deintercalation of Li + , and suppress Mn 3+ generation at high temperatures and provide improved structural stability.

LiMn2O4 and LiNi0.5Mn1.5O4 spinel cathode materials powder was successfully synthesized by an ultrasonic-assisted co-precipitation (UACP) method. The geometry structures of LiMn2O4 and LiNi0.5Mn1.5O4 are successful optimized and the corresponding electronic structures are then calculated by density functional theory (DFT) plane-wave pseudopotential method. The initial discharge capacity of LiMn2O4 and LiNi0.5Mn1.5O4 are 130.9 and 130.5 mAh·g− 1, respectively. The calculated average voltages of LixMn2O4 and LixNi0.5Mn1.5O4 at the range of 0 ≤ x ≤ 1 are 4.28 and 4.66 V, and the errors are 4.39% and 0.74% compared with electrochemical experiment value, respectively. The increase of voltage after doping is related with the different filling of electrons in M–O6 octahedron framework after the intercalation/deintercalation of Li+, and lithium element exists in spinel materials in form of ions.

Spinel LiNi0.5Mn1.5O4 and LiMn1.4Cr0.2Ni0.4O4 cathode materials have been successfully synthesized by the sol–gel method using citric acid as a chelating agent. The structure and electrochemical performance of these as-prepared powders have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and the galvanostatic charge–discharge test in detail. XRD results show that there is a small Li y Ni1-y O impurity peak placed close to the (4 0 0) line of the spinel LiNi0.5Mn1.5O4, and LiMn1.4Cr0.2Ni0.4O4 has high phase purity, and the powders are well crystallized. SEM indicates that LiMn1.4Cr0.2Ni0.4O4 has a slightly smaller particle size and a more regular morphological structure with narrow size distribution than those of LiNi0.5Mn1.5O4. Galvanostatic charge–discharge testing indicates that the initial discharge capacities of LiMn1.4Cr0.2Ni0.4O4 and LiNi0.5Mn1.5O4 cycled at 0.15 C are 129.6 and 130.2 mAh g−1, respectively, and the capacity losses compared to the initial value, after 50 cycles, are 2.09% and 5.68%, respectively. LiMn1.4Cr0.2Ni0.4O4 cathode has a higher electrode coulombic efficiency than that of the LiNi0.5Mn1.5O4 cathode, implying that Ni and Cr dual substitution is beneficial to the reversible intercalation and de-intercalation of Li+.

The silk fibroin blend membranes were prepared by adding a small amount of poly (vinyl alcohol) (PVA) and heparin. By controlling the preparation conditions, the tensile strength and elongation at break reached to 8.86 MPa and 231.8%, respectively. Meanwhile the in vitro antithrombogenecity significant increased. The clot times (APTT, TT and PT) all exceeded the measurement limit of clot detection instrument. It is expectable using these natural materials to prepare small caliber vessel.

A novel prosthesis using silk fibroin with blending heparin and sulfonated silk fibroin was studied. Anticoagulation activities of heparin/silk fibroin and sulfonated silk fibroin/silk fibroin vascular and mechanical property results showed that heparin/silk fibroin and sulfonated silk fibroin/silk fibroin vascular could meet the requirement of small caliber grafts. This study indicated that silk fibroin could be used for developing tissue engineering biological vascular grafts that could use for human coronary or low extremity artery bypasses.

Tetramethylpyrazine(TMPZ) is an active ingredient of a Chinese herbal medicine Chuanxiong (Liqusticum wallichii Franchat). In order to enhance its stability and delivery in vivo TMPZ-capped poly(ethylene glycol) conjugate was designed and synthesized efficiently by the condensation reaction of 2-cardoxyl-3, 5, 6-trimethylpyrazine (TMPZCOOH) with PEG(M=2000) in the presence of dicyclohexylcarbodiimide (DCCI). The TMPZ-PEG conjugate obtained was then purified by gel filtration chromatography (SephadexG-15 column,1.6×100cm; eluent: distilled water) and characterized by FTIR, UV spectra. FTIR (KBr): 2868cm-1(CH2), 1718cm-1(C=O), 1455cm-1 (-C=N-), 1113cm-1(O-CH2-CH2). The degree of end-capping of TMPZ per PEG molecules was estimated to be 87% from UV absorbance at 294nm. The anticoagulant activity of the conjugate was evaluated by in vitro coagulation time test. The result showed that the activated partial thromboplastin time (APTT) of the TMPZ-PEG conjugate is nearly equal to that of blank plasma in our experiment conditions, this behavior is similar to that of TMPZ. But TMPZCOOH, one of the main metabolic products of TMPZ in vivo, exhibited more potent anticoagulant activity than TMPZ and TMPZ-PEG, its APTT is even larger than the maximum clotting time set by the instrument. It is also found that APTT of the conjugate increased as the time of the sample stayed in water bath at 37°C. This is probably because the ester bond between TMPZCOOH and PEG hydrolyzed during the stay time and released the free TMPZCOOH.

The citric acid (CA) was added to the silk fibroin and Polyvinyl Alcohol (PVA) copolymer system. The blending 4% PVA was for improving the mechanical properties of the silk fibroin films. Citric acid amount varies from 0.5% to 2% of weight. The antithrombogenecity was characterized by in vitro clot time of prothrombin time (PT), the Activated partial thromboplastin time (APTT) and thrombin time (TT). The mechanical properties of the blending films were measured and the tensile strength and breaking elongation of films reached to 25.3MPa and 102%. The anticoagulant property results indicated that APTT and TT prolonged significantly, but PT has no effective change. We discussed the relationship between the structure and properties and proposed an anticoagulant mechanism.

Silicon carbon nitride (SiCN) films have been deposited on silicon wafers by microwave plasma chemical vapor deposition (MPCVD). Gas mixture of H2, CH4, N2, and SiH4 was used as precursors, in which the flow rate of N2 was changed. X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy were employed to characterize the composition and bonding structures, while field-emission scanning electron microscopy were used to investigate the microstructure of the films. With increasing the flow rate of N2 from 50 sccm to 300 sccm, the SiCN films changed from amorphous to nanocrystalline. Characteristic current-voltage measurements indicate a low turn-on field of 10.8 V/µm. Field emission current density of 4.5 mA/cm2 has been observed at 20 V/µm.

Carbon nitride films were grown on Si substrates by a microwave plasma chemical vapor deposition method, using mixture of N2, CH4 and H2 as precursor. Scanning electron microscopy shows that the films consisted of a large number of hexagonal crystallites. The dimension of the largest crystallite is about 3 µm. The X-ray photoelectron spectroscopy suggests that nitrogen and carbon in the films are bonded through hybridized sp2 and sp3 configurations. The X-ray diffraction pattern indicates that the major part of the films is composed of α-, β-, pseudocubic C3N4 and graphitic C3N4. The Raman peaks match well with the calculated Raman frequencies of α- and β-C3N4, revealing the formation of the α- and β-C3N4 phase.

CeO2 nanoparticles coated by sodium bis(2-ethylhexyl) sulfosuccinite have been prepared by using the microemulsion method. An average particle size of 2-3 nm was revealed by using transmission electron microscopy. X-ray diffraction shows that the CeO2 nanoparticles remain the CaF2-type cubic structures as the bulk crystal. Extended X-ray absorption fine structure technique is used to probe the local atomic structures around the absorber Ce. A double Gaussian model is used to deduce the structural parameters of the first coordination shell. Bulk CeO2 with eight oxygen atoms located at 2.338 Angstrom was used as the reference sample to extract the backscattering amplitude and phase shift of the Ce-O bond. Our EXAFS data suggest that in CeO2 nanoparticles, the oxygen coordination number around Ce has no obvious decrease, but the bond-length of Ce-O is obviously elongated. It is postulated that a surface/core model may be used to describe the local atomic structures in the CeO2 nanoparticles. (C) 2000 Elsevier Science S.A. All rights reserved.

Boron carbide nanobelts have been synthesized successfully by carbothermal growth method. Boron oxide, activated carbon, gallium oxide and sodium chloride in the molar ratios of 1: 5: 0.03: 0.2 were used as raw materials. The width and thickness of the nanobelts range from 1 to 10 μm, and 80 to 150 nm respectively. The length is up to 50–200 μm. Diffraction peaks in the XRD pattern can be indexed to rhombohedral boron carbide with lattice parameters of a=5.616Å, c=12.067 Å. SAED pattern recorded along [ 010 ] zone axis shows (104 ) growth direction. A vapor–liquid–solid (VLS) growth process on the active catalyst surface is supposed to interpret the growth mechanism of as–synthesized nanobelts.

Diamond-like carbon (DLC) films have been prepared by electrolysis of methanol solution using a pulse-modulated source. The deposition rate of the films is enhanced significantly compared to that of dc value. That the films do not contain bonded hydrogen is confirmed by infrared spectra. The structures of the films are characterized by Raman spectroscopy. These films show chemical inertness and hardness values in the range 12.5–19 GPa. Current-voltage characteristics of the films are measured, indicating that the resistivity is in the 107 Ω cm range and the breakdown field is larger than 1 MV cm−1.