基于三电层模型的交流电渗流速分析

微通道内交流电渗微泵的流速与电极表面双电层的结构与电荷分布密切相关,根据传统双电层理论和交流电渗速度公式可以预测交流电渗流速分布和速度峰值处的转折频率。试验发现,由此得出的交流电渗流速峰值比试验值大数倍。考虑紧密层和中间层厚度对交流电渗流的影响,提出三电层模型,给出三电层等效厚度和等效相对介电常数的求解方法,对传统的交流电渗速度公式进行修正,得出修正后的时间平均流速、位置平均流速和转折频率表达式。以宽度和间距均为20?m的平行电极阵列为试验对象,对其施加相位差90°的四相行波电场,用电荷耦合元件(Charge-coupled device,CCD)记录流场中荧光粒子的轨迹并用micro-PIV方法计算流场速度。设置不同的电层厚度参数对试验进行仿真。结果表明,紧密层厚度为几个溶剂分子大小(0.5 nm),而且中间层厚度为电极表面微观起伏高度(5 nm)时,仿真和试验结果非常接近,这表明三电层模型和修正后流速公式的有效性。

基于随机三层环形子电路的路径级NBTI老化预测

纳米工艺水平下,电路可靠性成为电路设计的重要问题。其中,老化又是电路可靠性的主要威胁之一。所以,为了制定老化缓解措施,评估老化以避免电路故障变得至关重要。提出了一种基于随机三层环形子电路的路径级老化预测框架,该框架将NBTI效应作为一种诱导退化机制得到三层环形子电路10年内老化延时,并使用线性回归模型对其老化延时趋势进行学习。之后,基于该模型,可以快速得到电路关键路径的老化延时。实验结果表明,提出的框架在保证精度的同时,时间效率也有较大的提升。

A review of the carbon coating of the silicon anode in highperformance lithium-ion batteries

In the development of rechargeable lithium ion batteries(LIBs),silicon anodes have attracted much attention because of their extremely high theoretical capacity,relatively low Li-insertion voltage and the availability of silicon resources.However,their large volume expansion and fragile solid electrolyte interface(SEI)film hinder their commercial application.To solve these problems,Si has been combined with various carbon materials to increase their structural stability and improve their interface properties.The use of different carbon materials,such as amorphous carbon and graphite,as three-dimensional(3D)protective anode coatings that help buffer mechanical strain and isolate the electrolyte is detailed,and novel methods for applying the coatings are outlined.However,carbon materials used as a protective layer still have some disadvantages,necessitating their modification.Recent developments have focused on modifying the protective carbon shells,and substitutes for the carbon have been suggested.

Improving electrochemical performances of LiFePO_4 /C cathode material via a novel three-layer electrode

As an improvement on the conventional two-layer electrode （active material layerlcurrent collector）, a novel sandwich-like three-layer electrode （conductive layerlactive material layertcurrent collector） for cathode material LiFePO4/C was introduced in order to improve its electrochemical performance. LiFePO4/C in the three-layer electrode exhibited superior rate capability in comparison with that in the two-layer electrode in accordance with charge-discharge examination. Cyclic voltammetry and electrochemical impedance spectroscopy indicated that Fe3＋/Fe2＋ redox couple for LiFePO4 in the three-layer electrode displayed faster kinetics, better reversibility and much lower charge transfer resistance than that in the two-layer electrode in electrochemical process. For three-layer electrode, the holes in the surface of active material layer were filled by smaller acetylene black grains, which formed electrical connections and provided more pathways to electron transport to/from LiFePO4/C particles exposed to the bulk electrolyte.

3D LBFGS inversion of controlled source extremely low frequency electromagnetic data

The controlled source extremely low frequency （CSELF） electromagnetic method is characterized by extremely long and powerful sources and a huge measurement range. Its electromagnetic field can therefore be affected by the ionosphere and displacement current. Research on 3D forward modeling and inversion of CSELF electromagnetic data is currently in its infancy. This paper makes exploratory attempts to firstly calculate the 1D extremely low frequency electromagnetic field under ionosphere-air-earth coupling circumstances, and secondly analyze the propagation characteristics of the background electromagnetic field. The 3D staggered-grid finite difference scheme for solving for the secondary electric field is adopted and incorporated with the 1D modeling algorithm to complete 3D forward modeling. Considering that surveys can be carried out in the near field and transition zone for lower frequencies, the 3D Limited-memory Broyden-Fletcher-Goldfarb-Shanno （LBFGS） inversion of CSELF electromagnetic data is presented （in which the sources, or primary fields, are included）, with the aim of directly inverting the impedance data, regardless of where it is acquired. Derivation of the objective functional gradient is the core component in the inversion. Synthetic tests indicate that the well-chosen approximation to the Hessian can significantly speed up the inversion. The model responses corresponding to the coexistence of conductive and resistive blocks show that the off-diagonal components of tensor impedance are much more sensitive to the resistivity variation than the diagonal components. In comparison with conventional scalar inversion, tensor inversion is superior in the recoveries of electric anomalies and background resistivity.

Applications of IoT in Smart Grid

In this paper,the basic requirements of the smart grid in China are studied.By applying Internet of Things(IoT) technologies,various intelligent services can be created.The development of the smart grid would rely heavily on the application of IoT.The three-layer architecture of IoT for the smart grid in China is introduced.Various information and communication technologies of IoT applied to smart grid are discussed.Particularly,several typical IoT application solutions such as power transmission line monitoring,smart patrol,smart home and electric vehicle management,are provided.

Weakly Coupled Three-Layer Quantum Dot with a Charged Impurity inMagnetic Field

The states of a weakly coupled 3-quantum-dot system with an external charged impurity located on the -axis are studied in a magnetic field. The evolutions of the true ground state with the magnetic field B are obtained for various impurity cases. It is found that the negative charge impurity would promote the phase transition of the true ground state.

Output Characteristics of n-Buried-pSOI Sandwiched RF Power LDMOS

A novel n-buried-pSOI sandwiched structure for an RF power LDMOS is proposed. The output characteristics of the RF power LDMOS are greatly affected by the drain-substrate parasitic capacitance. The output characteristics become better as the drain-substrate parasitic capacitance decreases. Results show that the drain-substrate capacitance of the n- buried-pSOI sandwiched LDMOS is 46.6% less than that of the normal LDMOS,and 11.5% less than that of the n-buried- pSOI LDMOS,respectively. At l dB compression point,its output power is 188% higher than that of the normal LDMOS, and 10.6% higher than that of the n-buried-pSOI LDMOS, respectively. The power-added efficiency of the proposed structure is 38.3%. The breakdown voltage of the proposed structure is 11% more than that of the normal LDMOS.

Evaluation of coronary artery bypass graft patency using three-dimensional reconstruction and flow study of electron beam tomography

Objective To establish and evaluate two protocols for the noninvasive visualization and assessment of coronary artery bypass graft (CABG) patency on electron beam tomography (EBT).Methods Two hundred and fourteen consecutive patients who underwent coronary artery bypass graft surgery were scanned using both EBT angiography with 3-dimensional reconstruction and EBT flow study with time-density-curve analysis.Results There were 589 CABGs evaluated in this study (10 grafts were excluded because of artifacts). Among them, 133 (98.5％) of 135 arterial grafts were patent, and 345 (77.7％) of 444 saphenous-vein grafts were patent. Within 5 years or between 5 and 10 years after operation, arterial graft patency exceeded venous graft patency (P ＜ 0.001 ). Three-dimensional EBT angiography achieved higher sensitivity, specificity and accuracy (97.7％, 94.1％ and 96.7％, respectively) than did EBT flow study (88.4％, 82.4％ and 85.2％, respectively) for evaluating occlusion or patency of CABG. The intra-graft flow of patent arterial and venous grafts were 4.9 ± 2.2 mi · min-1 · g-1 and 6.9 ± 2.8 mi · min-1 · g-1,respectively (P＜0.001).Conclusion The combination of EBT three-dimensional reconstruction and flow study can be more effective in the assessment of CABG anatomy and quantification of patent CABG blood flow.

BDS triple-frequency carrier-phase linear combination models and their characteristics

An investigation has been made on the models and characteristics of triple-frequency carrier-phase linear combinations for the Bei Dou Navigation Satellite System(BDS). Based on the three frequencies of the BDS, three categories of combinations are developed: ionosphere-free combinations(i.e., those that eliminate the ionospheric effect), minimum-noise combinations(those that mitigate the effects of thermal noise and multiple paths), and troposphere-free combinations(those that mitigate tropospheric effects). Both the ionosphere-free and troposphere-free combinations can be expressed as planes, whereas the minimum-noise combinations can be expressed as a line. The relationships between these three categories of linear combinations are investigated from the perspective of geometry. The angle between the troposphere-free plane and ionosphere-free plane is small, while the angles between the troposphere-free plane and the minimum-noise line, and between the ionosphere-free plane and the minimum-noise line, are large. Specifically, the troposphere-free plane is orthogonal to the minimum-noise line. By introducing the concepts of lane number and integer ionosphere number, the characteristics of the long-wavelength integer combinations and ionosphere-free integer combinations are investigated. The analysis indicates that the longest wavelength that can be formed for integer combinations is 146.53 m, and the ionosphere-free integer combinations all have large noise amplification factors. The ionosphere-free integer combination with minimum noise amplification factor is(0, 62, 59). According to the lane number, integer ionosphere number, and noise amplification factor, optimal integer combinations with different characteristics are presented. For general short baselines and long baselines, three independent integer combinations are suggested.

Three-dimensional hierarchical Pt-Cu superstructures

Three-dimensional （3D） hierarchical Pt-Cu tetragonal, highly branched, and dendritic superstructures have been synthesized by a facile template-free hydrothermal approach, showing growth patterns along （111, 110）, （111）, and （100） planes, respectively. These structures have been characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, energy dispersive X-ray spectroscopy （EDX）, inductively coupled plasma optical emission spectrometry （ICP-OES） and a detailed formation mechanism has been developed, which shows that the in situ formed 12 and the galvanic replacement reaction between Cu and Pt4, may guide the formation of these superstructures. The comparative electrocatalytic properties have been investigated for methanol and ethanol oxidation. Due to their interconnected arms, sufficient absorption sites, and exposed surfaces, these superstructures exhibit enhanced electrocatalytic performance for electro-oxidation of methanol and ethanol when compared with commercial Pt/C and Pt black.

A new unequal-weighted triple-frequency first order ionosphere correction algorithm and its application in COMPASS

As the introduction of triple-frequency signals in GNSS,the multi-frequency ionosphere correction technology has been fast developing.References indicate that the triple-frequency second order ionosphere correction is worse than the dual-frequency first order ionosphere correction because of the larger noise amplification factor.On the assumption that the variances of three frequency pseudoranges were equal,other references presented the triple-frequency first order ionosphere correction,which proved worse or better than the dual-frequency first order correction in different situations.In practice,the PN code rate,carrier-to-noise ratio,parameters of DLL and multipath effect of each frequency are not the same,so three frequency pseudorange variances are unequal.Under this consideration,a new unequal-weighted triple-frequency first order ionosphere correction algorithm,which minimizes the variance of the pseudorange ionosphere-free combination,is proposed in this paper.It is found that conventional dual-frequency first-order correction algorithms and the equal-weighted triple-frequency first order correction algorithm are special cases of the new algorithm.A new pseudorange variance estimation method based on the three carrier combination is also introduced.Theoretical analysis shows that the new algorithm is optimal.The experiment with COMPASS G3 satellite observations demonstrates that the ionosphere-free pseudorange combination variance of the new algorithm is smaller than traditional multi-frequency correction algorithms.

Abnormal distribution of ionospheric electron density during November 2004 super-storm by 3D CT reconstructions from IGS and LEO/GPS observations

Using time-dependent 3D tomography method, the electron density distributions in the low-latitude ionosphere during November 2004 super-storm are reconstructed from GPS observations of joint ground-based IGS network and onboard CHAMP/GRACE satellites. The reconstructed electron densities are validated by satellite in situ measurements of CHAMP and GRACE satellites. It is indicated by computer tomography （CT） reconstructions that the long-lived positive storm phase during the first main phase of the storm （November 8） is mainly attributed to enhancement of electron density in the upper F region above the F2 peak. It is found by the CT imaging that the top-hat-like F2-3 double layers occurred in the equatorial ionization anomaly region during the main phase of the storm （at forenoon of November 8）. The structures of column-like enhanced electron density are found at the time near the minimum of Dst and in the longitudinal sector about 157°E, which extend from the topside ionosphere toward plasmasphere, reaching at least about 2000 km as high. Their footprints stand on the two peaks of the EIA.

Realizing high-performance ternary organic solar cell with thick active layer via incorporating a liquid crystalline small molecule as a third component

In the past two decades, organic solar cells （OSCs） have at- tracted significant attention owing to their merits of achieving light-weight, flexible, low-cost devices [1,2]. Ternary OSC as an efficient way to improve the power conversion efficiencies （PCEs） of OSCs has inspired great interest from researchers to investigate ternary OSCs and result in many efficient de- vices. Ternary OSCs allow collecting high- and low-energy photons by separated semiconductors in a single active layer to minimize the thermalization loss and broaden absorption range to improve the performance of OSCs. However, most reported ternary OSCs only have active layer of about 100 nm in thickness.