基于双阈值的高精度锂电池主被动均衡策略

针对锂离子电池充放电过程中电量表征变化幅度大、精度低的问题,提出了一种通过实时分段进行双阈值控制的主被动均衡控制策略。该策略结合锂离子电池开路电压与荷电状态(SOC)的关系曲线,实时分段并合理调整均衡控制方向。通过双阈值的精确调控,提高充放电精度;利用主被动均衡电路中的被动均衡小电流特点,增加单体电池在充放电末期的反应时间,实现准确和安全的电池充放电目的。实验结果表明,锂离子电池组充放电过程中进行分段双阈值主被动均衡控制,可以在电池组充放电速度不变的情况下,提高约2%的充电精度,充电末期稳定减缓电流和电压,证明了控制方法的可行性。

In situ studies of energy-related electrochemical reactions using Raman and X-ray absorption spectroscopy

Electrochemical energy conversion technologies involving processes such as water splitting and O_(2)/CO_(2) reduction,provide promising solutions for addressing global energy scarcity and minimizing adverse environmental impact.However,due to a lack of an in-depth understanding of the reaction mechanisms and the nature of the active sites,further advancement of these techniques has been limited by the development of efficient and robust catalysts.Therefore,in situ characterization of these electrocatalytic processes under working conditions is essential.In this review,recent applications of in situ Raman spectroscopy and X-ray absorption spectroscopy for various nano-and single-atom catalysts in energy-related reactions are summarized.Notable cases are highlighted,including the capture of oxygen-containing intermediate species formed during the reduction of oxygen and oxidation of hydrogen,and the detection of catalyst structural transformations occurring with the change in potential during the evolution of oxygen and reduction of CO_(2).Finally,the challenges and outlook for advancing in situ spectroscopic technologies to gain a deeper fundamental understanding of these energy-related electrocatalytic processes are discussed.

Preparation and Characterization of Alumina Membranes on Capillary Supports： Effect of Film-coating on Crack-free Membrane Preparation

Ceramic capillary membrane has received much attention due to its relatively high pack density and favorable mechanical strength.However,it is difficult to prepare capillary membrane on its thin support by a dip-coating method.In this study,alumina microfiltration membranes were prepared on the inner surface of alumina capillary support(outer diameter 4 mm,inner diameter 2.5 mm)by a dip-coating method.Scanning electron microscopy(SEM)observation,gas bubble pressure(GBP)method and membrane permeation test were carried out to evaluate membrane performance.Two major effects in preparation of crack-free membrane,capillary filtration and film-coating,upon the thin support were studied.The as-prepared crack-free membrane presents a narrow pore size distribution,a mean pore size of about 0.6μm and a high pure water flux of 86000 L·m -2 ·h -1 ·MPa.It is proved that the membrane thickness should be sufficiently large to overcome the defects of support surface,but it is only one of the prerequisites for the formation of crack-free membrane.Furthermore,it is demonstrated that the capillary filtration effect is greatly restricted for thin capillary support with the dip-coating method and the film-coating effect plays a crucial role in the formation of crack-free membrane.

Recent Advances in Flame Tomography

To reduce greenhouse gas emissions from fossil fuel fired power plants,a range of new combustion technologies are being developed or refined,including oxy-fuel combustion,co-firing biomass with coal and fluidized bed combustion.Flame characteristics under such combustion conditions are expected to be different from those in normal air fired combustion processes.Quantified flame characteristics such as temperature distribution,oscillation frequency,and ignition volume play an important part in the optimized design and operation of the environmentally friendly power generation systems.However,it is challenging to obtain such flame characteristics particularly through a three-dimensional and non-intrusive means.Various tomography methods have been proposed to visualize and characterize flames,including passive optical tomography,laser based tomography,and electrical tomography.This paper identifies the challenges in flame tomography and reviews existing techniques for the quantitative characterization of flames.Future trends in flame tomography for industrial applications are discussed.

Characterization of Zinc Passive Film by Sonication in 7 M KOH Solution

The influence of 40 kHz ultrasound radiation on the passivation behavior of zinc in 7 M KOH is presented. The results of potentiodynamic and potentiostatic measurements combined with the current oscillation caused by the irradiation were examined to explain the mechanism and the sequence of formation of the oxide films during passivation. In this study, sonication was also used to investigate both effects of the passivation duration and passivation potential on the structure of the oxide layers; the adherence of the layers was found to depend strongly on both parameters. Scanning electron microscopy-energy dispersive X-ray （SEM-EDX） analysis of the zinc surface provided complementary information on the oxide layer composition and structure.

Modeling and Characterizing Internet Backbone Traffic

With enormous growth of the number of Internet users and appearance of new applications, characterization of Internet traffic has attracted more and more attention and has become one of the major challenging issues in telecommunication network over the past few years. In this paper, we study the network traffic pattern of the aggregate traffic and of specific application traffic, especially the popular applications such as P2P, VoIP that contribute most network traffic. Our study verified that majority Internet backbone traffic is contributed by a small portion of users and a power function can be used to approximate the contribution of each user to the overall traffic. We show that P2P applications are the dominant traffic contributor in current Internet Backbone of China. In addition, we selectively present the traffic pattern of different applications in detail.

Preparation and Characterization of Gelatins from Two Sudanese Edible Insects

Gelatins extracted from two edible insects Aspongubus viduatus （melon bug） and Agonoscelis pubescens （sorghum bug） were studied. The two insects showed 27.0 and 28.2% crude protein, respectively. Extraction of gelatin using hot water gave high yield followed by mild acid and distilled water extraction, respectively. SDS-PAGE pattern showed low molecular weight chains, and the two gelatins contained protein with molecular weight of 40 kDa as main component. The differential scanning calorimetry thermograms results confirm no difference between extraction methods concerning the extracted gelatin quality. FTIR spectra of melon and sorghum bug gelatins were similar and the absorption bands were situated in more than 6 bands in melon bug gelatin and only 6 bands in sorghum bug gelatin. Amide II bands of gelatins from both melon and sorghum bug appeared at around 1554 cm^-1, while Amide I bands （1734-1632 cmt） appeared only in melon bug method 2 （MB2） and melon bug method3 （MB3）. Microstructures of the insect gelatin examined with the scanning electron microscope showed that melon bug exhibited the finest gelatin network with very small voids. Melon bug gelatin showed finer structure with smaller protein strands and voids than sorghum bug gelatin.

A novel integrated quantum circuit for high-order W-state generation and its highly precise characterization

Multipartite entangled states like the W-class are of growing interest since they exhibit a variety of possible applications ranging from quantum computation to genuine random number generation. Here, we present a universal setup to generate high-order single photon W-states based on three-dimensional integrated-photonic waveguide struc- tures. Additionally, we present a novel method to charac- terize the device＇s unitary by means of classical light only.

Preparation and characterization of Al/B/Fe_2O_3 nanothermites

A sol-gel synthetic approach combined with an ultrasonic method was utilized to prepare Al/B/Fe2O3 nanothermites.The structure and properties of the prepared nanothermites were characterized by thermogravimetric analysis,differential scanning calorimetry,scanning electron microscopy,X-ray diffraction,and an impact sensitivity test.The results verified that the nano-aluminum and the micro-boron were uniformly dispersed in the pores of the iron oxide gel.The heat of the prepared Al/B/Fe2O3 nanothermites was 1.3 times that of the simple physically mixed sample.In addition,the heat of the combustion test showed that these materials were indeed energetic.Small-scale safe experiments also showed that the prepared materials through sol-gel were relatively insensitive to standard impact.

Investigation of the correlation between internal gradients and dephasing effect in inhomogeneous field

Internal magnetic gradient plays a significant role in Nuclear Magnetic Resonance(NMR)measurements of fluid saturated porous media.The quantitative characterization and application of this physical phenomenon could effectively improve the accuracy of NMR measurements and interpretations.In this paper,by using the equivalent magnetic dipole method,the three-dimensional distribution of internal induced magnetic field and its gradients in the randomly packed water saturated glass beads are quantitatively characterized.By simulating the diffusive motion of water molecules in porous media with random walk method,the computational dephasing effects equation related to internal gradients is deduced.Thereafter,the echo amplitudes are obtained and the corresponding T2-G spectrum is also inverted.For the sake of verifying the simulation results,an experiment is carried out using the Halbach core analyzing system(B0=0.18 T,G=2.3 T/m)to detect the induced internal field and gradients.The simulation results indicate the equivalent internal gradient is a distribution of 0.1-0.3 T/m,which matched well with the experimental results.

Fabrication and characterization of transparent conducting titanium-zinc oxide nanostructured thin films

Nano transparent conducting titanium-zinc oxide(Ti-Zn O) thin films were prepared on glass substrates by radio frequency(RF) magnetron sputtering technique. The deposited films are characterized by X-ray diffraction(XRD), four-probe meter and UV-visible spectrophotometer. The effects of Ti-doping content on the structural, optical and electrical properties of the films are investigated. The XRD results show that the obtained films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the(002) crystallographic direction. The structural and optoelectronic characteristics of the deposited films are subjected to the Ti-doping content. The Ti-Zn O sample fabricated with the Ti-doping content of 3%(weight percentage) possesses the best crystallinity and optoelectronic performance, with the highest degree of preferred(002) orientation of 99.87%, the largest crystallite size of 83.2 nm, the minimum lattice strain of 6.263×10^(-4), the highest average visible transmittance of 88.8%, the lowest resistivity of 1.18×10^(-3) Ω·cm and the maximum figure of merit(FOM) of 7.08×10~3 Ω^(-1)·cm^(-1). Furthermore, the optical bandgaps of the films are evaluated by extrapolation method and observed to be an increasing tendency with the increase of the Ti-doping content.