Two Time-Scale Feedback Stabilization of Linear Time-Varying Singularly Perturbed Systems

The stabilization of a class of singularly perturbed linear time-varying systems is considered through the separate stabilization of two lower dimensional subsystems in two different time-scales. A composite stabilizing controller is synthesized from the separate stabilizing controllers of the two subsystems, the mutually independent gains of which do not require knowledge of the small singular perturbation parameter.     

An Upper Bound for the Singular Parameter in a Stable,Singularly Perturbed System

This paper considers the problem of stability of a singularly perturbed system and of finding an upper bound for the parameter when the order of the system changes as a result of parameter perturbation. By means of the contraction mapping technique, conditions have been derived for determining explicitly the range of parameter perturbation such that both bounded-input-bounded-output and asymptotic stabilities are insured. In addition, bounds of the state and output of the singularly perturbed system can be found. Two examples are given to illustrate the application and significance of the results.     

Transport Phenomena in Heterogeneous Media1

Classical work on transport in heterogeneous media is reviewed to show the broad interest in it as well as the specific need for a thorough treatment of a more comprehensive model. Such a model is presented and it consists of a random distribution of one or more dispersed phases in a continuous phase. Both the stab and spherical geometry are also considered. Both the transient and steady state transport solutions are developed for each of three different cases. The equivalent diffusivities are extracted from the steady state solutions. Applications are considered to illustrate the validity of the work. It is emphasized that the flux J_i for phase i can be complex as discussed elsewhere in the literature and all of this without any detraction from the exposition presented. It is also pointed out that this exposition is apparently the first to establish the connection between a realistic model, its transient solutions and its steady state solutions from which the equivalent diffusivities have been extracted. In the case of dead-end pores the results suggest application to experimental data to serve as a precision test for the presence and amount of dead-end pores. The advantages of testing under steady state conditions are discussed in detail. An appropriate diffusion cell design is referenced. The results can be useful in the research and design of barrier materials, catalysts, etc.     

An Age Dependent Epidemic Model*

The model presented here describes the spread of an infection in a population by keeping track of the chronological ages of the participants as well as their “class ages” (i.e. the length of time since entering their present state). The reasoning behind this model is similar to that used in the equation of age dependent population growth.     

Partial derivative properties of multivariable cascaded networks1

Some partial derivative properties of the impedance function of a resistively-terminated network which is a cascade of m lossless two-ports of variables p₁ to p_m dre established. Those cases where some of the lossless two-ports are lowpass or highpass ladder networks with all of their transmission zeros at the origin or at infinity are also examined. Necessary and sufficient conditions involving partial derivatives and under which an m-variable reactance or positive real function can be realized as the impedance function of a p_i-variable lowpass or highpass ladder network, with all of its transmission zeros at p_i = 0 or p_i = ∞, and terminated in a reactance or positive real impedance function in the other variables are derived.     

类锌W44+离子双电子复合速率系数的理论研究

利用全相对论组态相互作用理论方法,计算了类锌W44+离子从基态3s23p63d104s2经过双激发态(3s23p 63d104s2)-1nln'l'(n=4、5;n'=4～15)的双电子复合(DR)速率系数,通过对不同电子激发的DR速率系数的比较,得知4s电子激发的DR速率系数在低温时给出了主要贡献,而3d的贡献在高温时突出;分别分析了不同电子激发的DR速率系数随l'和n'的变化,由此给出了l'的截断值.     

一类SIR传染病离散模型的持久性与稳定性

本文探讨一类SIR传染病离散模型的持久性和全局稳定性。     

“英特尔未来教育”在高校基础课程教学中的应用

基础课程教学是高校教育的奠基工程，它虽然不是学生专业水平的决定性课程，但它却能影响整个学生的专业水平，对提高大学生素质、培养各级各类人才，具有全局性、基础性和先导性作用。培养和发展学生的创新精神与实践能力、收集和处理信息的能力、主动和自主获取新知识的能力、分析与解决问题的能力、交流与协作的能力以及对自然环境和人类社会的责任感与使命感是基础课程教学改革的基本思想，以学生发展为本是基础课程教学改革的中心任务。     

Quantum Phases of SrCu2(BO3)2 from High-Pressure Thermodynamics

<正>In recent years, theoretical proposals for exotic states in quantum magnets are developing very rapidly, but many of these intriguing quantum phases and transitions have been difficult to realize experimentally. One class of such states is the valence bond solid, in which spins entangle locally and form symmetry-breaking singlet patterns.     

The Formulation of Bioelectric Source-field Relationships in Terms of Surface Discontinuities*

This paper considers the properties of scalar fields which satisfy Laplace's equation and which are either discontinuous or have discontinuous normal derivatives across some arbitrary surface. It is shown that expressions for the volume conductor fields of bioelectric sources can be readily obtained from the aforementioned relations. This procedure is simple and, in addition, preserves physical insight.     

Conjugated phthalocyanine-based framework as artificial SEI for over 400 Wh kg-1 lithium-metal batteryOA

High-voltage lithium-metal batteries（HVLMBs） are appealing candidates for next-generation high-energy rechargeable batteries, but their practical applications are still limited by the severe capacity degradation,attributed to the poor interfacial stability and compatibility between the electrode and the electrolyte. In this work, a 2D conjugated phthalocyanine framework（CPF） containing single atoms（SAs） of cobalt（CoSAs-CPF） is developed as a novel artificial solid–electrolyte interphase（SEI） in which a large amount of charge is transferred to the CPF skeleton due to the Lewis acid activity of the Co metal sites and the strong electron-absorbing property of the cyano group（-CN）, greatly enhancing the adsorption of the Li⁺ and regulating the Li⁺ distribution toward dendrite-free LMBs, which are superior to most of the reported SEI membranes. As a result, the Li||Li symmetrical cell with CoSAs-CPF-modified Li anodes（CoSAs-CPF@Li） exhibits a low polarization with an area capacity of 1.0 mAh cm^-2over 3500 h. The LiFePO₄（LFP） ||CoSAs-CPF@Li(LFP: 20 mg cm^-2) delivers an ultra-long cycling life of ≤1000 cycles with a high capacity retention of 98.6%. Remarkably, the high-voltage LiNi_0.8Co_0.1Mn_0.1O₂||Li@CoSAs-CPF(NCM811: 10 mg cm^-2) demonstrates a long cycling life of >800 cycles with a high capacity retention of 80%. Meanwhile, in situ ultrasonic transmission technology confirms the admirable ability of artificial CoSAs-CPF SEI to stabilize the Li-anode interface in pouch cells during cycling. Remarkably, the NCM811||Li@CoSAs-CPF pouch cell exhibits an energy density of 421 Wh kg^-1 and keeps 130 cycles with a low electrolyte/capacity ratio of 2.5 g Ah^-1. The strategy of constructing the CoSAs-CPF-reinforced Li anode provides a promising direction for high-energy-density HVLMBs with long cycling stability.     

H2 and H∞ optimal model reduction using genetic algorithms

The mathematical modeling of most physical systems, such as aerospace systems, heat processes, telecommunication systems, transmission lines and chemical reactors, results in complex high order models. The complexity of the models imposes a lot of difficulties in analysis, simulation and control designs. Several analytical model reduction techniques have been proposed in literature over the past few decades to reduce these difficulties. However, most of the optimal techniques follow computationally demanding, time consuming, iterative procedures that usually result in non-robustly stable models with poor frequency response resemblance to the original high order model in some frequency ranges. Genetic Algorithm (GA) has proved to be an excellent optimization tool in the past few years. Therefore, the aim of this paper will be to use GA to solve H₂ and H_∞ norm model reduction problems, and help obtain globally optimized nominal models.     

LiMn1-xNixO2的合成及表征

正交LiMnO2以其独有的特性,作为正极材料有着优良的表现,本文针对其缺点进行掺杂改性研究,使用凝胶溶胶法制备正极材料,研究了不同比例掺杂镍元素对其作为正极材料性能的影响,采用XRD,SEM,充放电测试等手段对该材料的结构和电化学性能进行了表征.     

Asymptotic stability of a viscoelastic elliptic shaft

A finite viscoelastic shaft whose model is based on the spring and dash-pot (Kelvin element) is asymptotically stable as long as its angular speed is less than or equal to the square root of the least eigenvalue of the system. We construct numerically the least eigenvalue by using an iteration method where a definite integral is evaluated by the GAUSQZ method. With this construction, we show that a viscoelastic elliptic shaped shaft with both ends pinned is more stable than the tapered shaft with both ends pinned, or with one end built in and the other end free.     

Pertubation in the I/O Map of a Non-linear Feedback System Caused by Large Plant Perturbation

This paper studies the perturbation in the input-output (I/O) map of a multi-input multi-output non-linear feedback system caused by large plant perturbations. It compares the effect of these perturbations on the given feedback system and on the nominally equivalent open-loop system. First the unity feedback system is considered, then a more general configuration—which includes the usual summing node as a special case—is analyzed. In both cases it is shown that the degree of desensitization provided by feedback is controlled by the linearized return difference operator.     

Sustainable management of riverine N2O emission baselinesOA

The riverine N₂O fluxes are assumed to linearly increase with nitrate loading. However, this linear relationship with a uniform EF_5r is poorly constrained, which impedes the N₂O estimation and mitigation.Our meta-analysis discovered a universal N₂O emission baseline(EF_5r = k/[NO₃^-], k = 0.02) for natural rivers. Anthropogenic impacts caused an overall increase in baselines and the emergence of hotspots, which constitute two typical patterns of anthropogenic sources. The k values of agricultural and urban rivers increased to 0.09 and 0.05, respectively, with 11% and 14% of points becoming N₂O hotspots. Priority control of organic and NH₄⁺ pollution could eliminate hotspots and reduce emissions by 51.6% and 63.7%,respectively. Further restoration of baseline emissions on nitrate removal is a long-term challenge considering population growth and declining unit benefits（ΔN-N₂O/N-NO₃^-）. The discovery of EF lines emphasized the importance of targeting hotspots and managing baseline emissions sustainably to balance social and environmental benefits.     

Cascade specific endogenous Fe3+ interference and in situ catalysis for tumor therapy with stemness suppressionOA

Cancer stem-like cells（CSCs）, featuring high tumorigenicity and invasiveness, are one of the critical factors leading to the failure of clinical cancer treatment such as metastasis and recurrence. However, current strategies suffer from the low stemness-inhibiting efficacy on CSCs by conventional molecular agents and the poor lethal effects against bulk tumor cells. Here we engineer a coordination nanomedicine by 2,5-dihydroxyterephthalic acid（DHT） complexing zinc ions(Zn²⁺) as a double-effect nanodisrupter of tumor iron（Fe） and redox homeostasis for catalysis-boosted tumor therapy with stemness inhibition.Taking advantage of the much higher binding force of DHT toward Fe³⁺, this nanomedicine can specifically chelate endogenous Fe³⁺into its nanostructure and release Zn²⁺, and the in situ formed hexacoordinated Fe-DHT conformation is of much enhanced reducibility in order to promote reactive oxygen species（ROS）production in tumors. The nanomedicine-mediated Fe depletion and ROS generation collectively induce CSC differentiation via downregulating the Wnt signaling and inducing forkhead box O3（FoxO₃）activation, respectively. Notably, the combined tumor-selective ROS generation and Zn²⁺-induced antioxidation dysfunction potently trigger intratumoral oxidative damage leading to both cellular apoptosis and ferroptosis. This nanomedicine, capable of synchronously treating CSCs and bulk tumor cells, has been demonstrated to effectively inhibit the growth, postoperative recurrence and metastasis of orthotopic triple-negative breast tumors in vivo, offering an encouraging candidate of cancer therapeutic agents for treating CSCs-enriched malignancy.