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A multiple pre-doping system with a looser structure displays small fractional volume expansion.

Our main purpose in this work is to investigate a new solution that represents a numerical behavior for one well-known nonlinear wave equation, which describes the Bona–Smith family of Boussinesq type. A numerical solution has been obtained according to the quintic B-spline collocation method. The method is based on the Crank–Nicolson formulation for time integration and quintic B-spline functions for space integration. The stability of the proposed method has been discussed and presented to be unconditionally stable. The efficiency of the proposed method has been demonstrated by studying a solitary wave motion and interaction of two and three solitary waves. The results are found to be in good agreement with the analytic solution of the system. We demonstrated the physical interpretation of some obtained results graphically with symbolic computation.

One of the major tasks in the reform of the National Natural Science Foundation of China during the new period is to sort out the knowledge system and optimize the discipline layout after finishing the adjustment of application codes. Based on the 14th Five-year Geosciences Development Plan of the National Natural Science Foundation of China, we propose a new discipline layout for the geological sciences (GS) in China. GS should focus on the prior fields and core scientific questions of “Earth system sciences and deep earth, deep sea, and deep space”, and in their respective sub-disciplines. While preserving essential traditional codes within these disciplines, we suggested to obsolete or merge outdated codes and raise special attention to new-rising subjects or interdisciplinary. According to the sub-disciplines’ characteristics, the geological sciences could be divided into four categories, i.e., basic, applied, cutting-edge and interdisciplinary subjects, and technology supporting subjects. Under the Earth system sciences framework, the authors suggest focusing on the core of basic disciplines, enrich applied fields, expand the cutting-edge and interdisciplinary disciplines, strengthen technological support, and promote a balanced development of sub-disciplines. Based on the investigation results of the discipline strategy, important sub-fields and headings of the GS are proposed. The research done at the GS should broaden its international scope and actively answer the major national requirements, with particular attention to crucial scientific problems in social and economic development. In short, the DGS should centralize efforts on the basic scientific research and national strategic needs. Following the development strategy of the Earth system sciences and deep earth, deep sea, and deep space, the authors suggest that improvements of the research ways and methods in the field of geological sciences, interdisciplinary cooperation and integration, promotions of new fields and sub-disciplines are all necessary. It is suggested to focus on the Earth system sciences, and continue to modify and merge the subjects following the guide of “Grand Geology”. More important, the authors suggest utilizing the rich geological resources in China to promote the development of geological sciences, enhance the international cooperation, and accelerate constructing an open geological big data platform.

EPEG (ethylene-glycol monovinyl polyethylene glycol)-AA (acrylic acid) copolymerization is a typical representative of free radical copolymerization for the preparation of PCs that has been discuss...

Silicon/carbon (Si/C) composites have rightfully earned the attention as anode candidates for high-energy-density lithium-ion batteries (LIBs) owing to their advantageous capacity and superior cycling stability, yet their practical application remains a significant challenge. In this study, we report the large-scale synthesis of an intriguing micro/nanostructured pore-rich Si/C microsphere consisting of Si nanoparticles tightly immobilized onto a micron-sized cross-linked C matrix that is coated by a thin C layer (denoted P-Si/C@C) using a low-cost spray-drying approach and a chemical vapor deposition process with inorganic salts as pore-forming agents. The as-obtained P-Si/C@C composite has high porosity that provides sufficient inner voids to alleviate the huge volume expansion of Si. The outer smooth and robust C shells strengthen the stability of the entire structure and the solid-electrolyte interphase. Si nanoparticles embedded in a microsized cross-linked C matrix show excellent electrical conductivity and superior structural stability. By virtue of structural advantages, the as-fabricated P-Si/C@C anode displays a high initial Coulombic efficiency of 89.8%, a high reversible capacity of 1269.6 mAh g

Compared to other high capacity anodes, Silicon (Si) has the highest gravimetric capacity, volumetric capacity, a relatively low discharge voltage and abundant storage on the earth, Si and Si based materials has become more and more popular in battery industries among which Silicon-Carbon (Si-C) core-shell particle has been one of the most promising and commercially feasible candidates to achieve ultrahigh capacity of the anode for lithium-ion batteries. Silicon-Carbon (Si-C) core-shell particle has been one of the most promising and commercially feasible candidates to achieve ultrahigh capacity of the anode for lithium-ion batteries. However, most silicon-based anode materials suffer from severe performance deterioration especially during fast charging process. Modeling the mechanical stress and deformation of anode particles is thus of great fundamental and practical interest to understand the mechanism of silicon-carbon anodes. We establish both computational and theoretical methods to describe the stress distribution and contact behaviors within and among Si-C particles, as well as the Li+ diffusion within Si particle. We further analyze the charging rate dependent behavior of the core-shell structure. Our analysis reveals a complete link between stress, charging rate, Li+ diffusion and the structural variables. Our study thus opens a novel pathway to design the structured high-capacity silicon-carbon at nano-scale for expanding Si-based anode application within limited amount beyond cylindrical configuration and increasing the glass ceiling of battery energy density based on graphite anode.

Honeynet technology is an active approach that is used to capture novel viruses and provide feedback on a matching immunization strategy. A compartmental model is formulated and analyzed to explore the interplay between virus epidemics and potency of a heterogeneous honeynet. Theoretical analysis of the model shows the conditions under which the minimum amount and best location in configuring a honeynet are determined. Furthermore, the honeypot with more system vulnerabilities is beneficial for mitigating the virus epidemic to a lower level, whereas the honeynet with a lower power law index is better for acquiring the virus samples. A number of numerical examples are presented to illustrate the theoretical analysis. On the basis of the results, some ideas for imposing restrictions on the spread of virus or improving the design of a honeynet are suggested.

Research in the area of kill signals for prevention of computer virus is of significant importance for computer users. The kill signals allow computer users to take precautions beforehand. In this paper, a computer virus propagation model based on the kill signals, called SEIR-KS model, is formulated and full dynamics of the proposed model are theoretically analyzed. An epidemic threshold is obtained and the existence and uniqueness of the virus equilibrium are investigated. It is proved that the virus-free equilibrium and virus equilibrium are locally and globally asymptotically stable by applying Routh–Hurwitz criterion and Lyapunov functional approach. The results of numerical simulations are provided that verifies the theoretical results. The availability of the proposed model has been validated with following observations: (1) the density of infected nodes in the proposed model drops to approximately 75% compared to the model in related literature; and (2) a higher density of KS is conductive to inhibition of virus diffusion.

Under investigation in this paper is the ( 2 + 1 ) -dimensional Kadomtsev–Petviashvili–Benjamin–Bona–Mahony equation. Based on bilinear method, the multiple rogue wave solutions and the novel multiple soliton solutions are constructed by giving some specific activation functions in the considered model. By means of symbolic computation, these analytical solutions and corresponding rogue waves are obtained, via Maple 18. By utilizing improved tan ( Φ ( ρ ) ∕ 2 ) -expansion technique the series of novel exact solutions in terms of rational, periodic and hyperbolic functions for the fractional cases are derived. Also, the semi-inverse variational principle is offered to get the solitary solutions. We construct the exact lump and rogue wave solutions, by solving the under-determined nonlinear system of algebraic equations for the specified parameters. Via various three-dimensional plots, curve plots, density plots and contour plots, dynamical characteristics of these waves are represented.

Acrylic acid–isobutylene polyethylene glycol (AA-TPEG) copolymers are typical of polycarboxylate superplasticizers (PCEs). AA-TPEG copolymers are prepared via free-radical polymerization with potassium persulfate as the initiator. The obtained copolymers were characterized by gel permeation chromatography (GPC) and infrared spectra (FTIR). The GPC method can break through the former limitations of the instruments and receive instantaneous unreacted and instantaneous monomer concentrations and not the initial monomer feeds. Since TPEG monomer is highly bulky, the common calculation methods for determining monomer reactivity ratios in copolymerization based on terminal copolymerization equation are not suitable. However, this study created non-linear least squares curve fitting of terminal copolymerization equation (NLLSQ-T) and penultimate copolymerization equation (NLLSQ-P) methods, which used Python’s NumPy, SciPy, and SymPy libraries to generate code and did numerical computations, bringing greater accuracy of monomer reactivity ratios. The monomer reactivity ratios were calculated with Fineman–Ross, Kelen–Tudos, YBR, NLLSQ-T, and NLLSQ-P methods and found to be r AA = 10.888, r′ AA = 1.131, r TPEG = 0.012, and r′ TPEG = 0.042 for AA-TPEG copolymers. Moreover, this study also explored specific copolymerization behavior of similar structure of copolymers with steric hindrance under penultimate copolymerization equation, such as dependence of the mole fractions in the copolymer on the mole fractions of unreacted monomers in solution, variation of copolymer compositions with conversion and sequence length distribution. The fluidity and flow loss of pastes containing PCEs were investigated, and the appropriate PCEs dosages resulted in a better workability of cement pastes.

The development of high-energy lithium-ion and sodium-ion capacitors (LICs and SICs) is still a challenge due to the kinetics mismatch between the insertion/deinsertion anode and adsorption/desorption cathode. Here, high-level N/P-doped Sn-carbon nanofibers (Sn-NP-CNFs) were fabricated via an electrospinning technique followed by pre-oxidization and carbonization. The N/P-doping increased the defects and carbon interlayer distance to inhibit the precipitation and volume expansion of the Sn and improve the Li/Na-adsorption, resulting in an ultrahigh pseudocapacitance and rate capability of the Sn-NP-CNF. An advanced LIC and SIC were composed of an activated carbon cathode and a Sn-NP-CNF anode. The LIC and SIC displayed ultrahigh energy densities (186.0 Wh kg−1 and 134.6 Wh kg−1) and power densities (20.0 kW kg−1 achieved at 22.2 Wh kg−1) with superior energy retentions (83.7% and 79.8% after 10,000 cycles at 5.0 A g−1).

Prussian blue analogs (PBAs) are considered as promising cathode materials in sodium-ion batteries. However, PBAs usually suffer from low electrical conductivity and high humid sensitivity, which results in the poor electrochemical kinetics and stability. In this work, a passivation strategy is proposed to solve these problems. The sodium iron hexacyanoferrate (PB) passivated by acetate ligands exhibits significantly improved electrochemical kinetics. It delivers a specific capacity of 128 mAh g−1 at 25 mA g−1. Even at 2 A g−1, the capacity still retains 94.6 mAh g−1. Most impressively, the passivated PB can maintain excellent electrochemical stability when exposed in the humid air for 7 days. Further investigations show that the strong physical interaction between the acetate ligands and the exposed Fe atoms can inhibit the readsorption of water and induce the electron transfer between low spin Fe and high spin Fe in PB. Thus, the surface passivation can efficiently enhance the electrical conductivity and electrochemical stability of PB.

Complex processes often work with multiple operation regions, it is critical to develop effective monitoring approaches to ensure the safety of chemical processes. In this work, a discriminant local consistency Gaussian mixture model (DLCGMM) for multimode process monitoring is proposed for multimode process monitoring by integrating LCGMM with modified local Fisher discriminant analysis (MLFDA). Different from Fisher discriminant analysis (FDA) that aims to discover the global optimal discriminant directions, MLFDA is capable of uncovering multimodality and local structure of the data by exploiting the posterior probabilities of observations within clusters calculated from the results of LCGMM. This may enable MLFDA to capture more meaningful discriminant information hidden in the high-dimensional multimode observations comparing to FDA. Contrary to most existing multimode process monitoring approaches, DLCGMM performs LCGMM and MFLDA iteratively, and the optimal subspaces with multi-Gaussianity and the optimal discriminant projection vectors are simultaneously achieved in the framework of supervised and unsupervised learning. Furthermore, monitoring statistics are established on each cluster that represents a specific operation condition and two global Bayesian inference-based fault monitoring indexes are established by combining with all the monitoring results of all clusters. The efficiency and effectiveness of the proposed method are evaluated through UCI datasets, a simulated multimode model and the Tennessee Eastman benchmark process.

In this paper, a new model of computer virus–antivirus propagation dynamics based on the topology nature of the Internet is established. We analyze theoretically the complex dynamics of the model and it is found that, unlike the existing models, the model admits two virus-free equilibria and possesses possibly two virus equilibria: one being antivirus-independent and the other being antivirus-dependent. Furthermore, the stability of virus-free equilibria is analyzed via a threshold value associated with the topology of the Internet and the model parameters. It is established that, if the threshold value is less than or equal to the unity, the virus-free equilibria are alternatively globally attractive, resulting in virus eradication, while if the threshold value is greater than unity, the antivirus-independent virus equilibrium is globally asymptotically stable, leading to virus diffusion, while the antivirus-dependent virus equilibrium also is globally asymptotically stable. Some numerical examples are presented to illustrate the analytical results.

A new computer virus propagation model with delay and incomplete antivirus ability is formulated and its global dynamics is analyzed. The existence and stability of the equilibria are investigated by resorting to the threshold valueR0. By analysis, it is found that the model may undergo a Hopf bifurcation induced by the delay. Correspondingly, the critical value of the Hopf bifurcation is obtained. Using Lyapunov functional approach, it is proved that, under suitable conditions, the unique virus-free equilibrium is globally asymptotically stable ifR0<1, whereas the virus equilibrium is globally asymptotically stable ifR0>1. Numerical examples are presented to illustrate possible behavioral scenarios of the mode.

A series of 4-(2-fluorophenoxy)-2-(1H-tetrazol-1-yl)pyridines bearing semicarbazone moieties were synthesized and evaluated for their in vitro antitumor potency. Some of the compounds (10b, 10c, 10e-10h, 10m-10p, 10r, and 11b) exhibited moderate to excellent antitumor activity as compared to sorafenib and PAC-1, as well as low levels of toxicity toward the human fetal lung fibroblast cell line WI-38. The most promising compound 10p (IC50 = 0.08, 0.36, 0.97 µM) was 45.1-, 6.1-, and 2.4-fold more active than sorafenib (IC50 = 3.61, 2.19, 2.32 µM), and 17, 3.2, and 2.9 times better than PAC-1 (IC50 = 1.36, 1.17, 2.83 µM) against three cancer cell lines (HT-29, H460, and MKN-45), respectively. In addition, further studies examining enzymatic activity suggested that the marked pharmacological activity observed might be ascribed to an inhibitory action against CRAf kinase.

This paper describes a new computer virus spreading model which takes into account the possibility of a virus outbreak on a network with limited anti-virus ability. Then, the model is investigated for the existence of equilibria and their stabilities are proved and illustrated. Moreover, it is found that these two factors are not only relative to the threshold value determining whether the virus becomes extinct or not, but that they are also relative to the virus epidemic levels. Theoretical and experimental results indicate that, in some ways, it would be practically possible to eradicate the virus or suppress its prevalence below a suitable level. Consequently, some suggestions are proposed that may help eradicate or suppress virus propagation over a real computer network.

Based on a set of reasonable assumptions, we propose a novel dynamical model describing the spread of computer virus. Through qualitative analysis, we give a threshold and prove that (1) the infection-free equilibrium is globally asymptotically stable if the threshold is less than one, implying that the virus would eventually die out, and (2) the infection equilibrium is globally asymptotically stable if the threshold is greater than one. Two numerical examples are presented to demonstrate the analytical results.

以Fe 3＋ 为铁源, 采用控制结晶技术合成了纳米FePO 4 · x H 2 O, 将FePO 4 · x H 2 O于500℃热处理4?h后得到纳米FePO4前驱体, 然后通过碳热还原在不同温度下煅烧合成橄榄石结构的纳米LiFePO4/C样品. 采用差热/热重、X射线衍射、扫描电镜、比表面测试、电化学性能测试等分析测试方法对纳米FePO 4 · x H 2 O、FePO 4 前驱体及不同煅烧温度下制得的纳米LiFePO 4 /C样品进行表征.研究结果表明, 700℃烧结10 h合成LiFePO 4 /C样品的粒径在40~100 nm左右, 比表面积为79.8 m 2 /g; 700℃煅烧合成样品在电压2.5~4.2 V, 倍率为0.1 C 、1 C 、5 C 、10 C 、15 C 时的放电比容量分别达到156.5、134.9、105.8、90.3和80.9 mAh/g, 具有较好的倍率性能; 样品还表现出较好的容量保持率.