Spectra of the Energy Operator of Four-Electron Systems in the Impurity Hubbard Model. Triplet State

We consider the energy operator of four-electron systems in an impurity Hubbard model and investigated the structure of essential spectra and discrete spectrum of the system in the first triplet state in a one-dimensional lattice. For investigation the structure of essential spectra and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model, for which the momentum representation is convenient. In addition, we used the tensor products of Hilbert spaces and tensor products of operators in Hilbert spaces and described the structure of essential spectrum and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model. The investigations show that there are such cases: 1) the essential spectrum of the system consists of the union of no more than eight segments, and the discrete spectrum of the system consists of no more than three eigenvalues;2) the essential spectrum of the system consists of the union of no more than sixteen segments, and the discrete spectrum of the system consists of no more than eleven eigenvalues;3) the essential spectrum of the system consists of the union of no more than three segments, and the discrete spectrum of the system is the empty set. Consequently, the essential spectrum of the system consists of the union of no more than sixteen segments, and the discrete spectrum of the system consists of no more than eleven eigenvalues.

The Structure of Essential Spectra and Discrete Spectrum of Three-Electron Systems in the Impurity Hubbard Model—Quartet State

We consider a three-electron system in the Impurity Hubbard model with a coupling between nearest-neighbors. Our research aim consists of studying the structure of essential spectrum and discrete spectra of the energy operator of three-electron systems in the impurity Hubbard model in the quartet state of the system in a v-dimensional lattice. We have reduced the study of the spectrum of the three-electron quartet state operator in the impurity Hubbard model to the study of the spectrum of a simpler operator. We proved the essential spectra of the three-electron systems in the Impurity Hubbard model in the quartet state is the union of no more than six segments, and the discrete spectrum of the system is consists of no more than four eigenvalues.

Structure of Essential Spectrum and Discrete Spectra of the Energy Operator of Five-Electron Systems in the Hubbard Model. Third and Fourth Doublet States

We consider a five-electron system in the Hubbard model with a coupling between nearest-neighbors. The structure of essential spectrum and discrete spectrum of the systems in the third and fourth doublet states in a v-dimensional lattice is investigated. We prove that the essential spectrum of the system in a third doublet state consists is the union of at most four segments, and discrete spectrum of the system is empty. We show that the essential spectrum of the system in a fourth doublet state consists of the union of at most seven segments, and discrete spectrum of the system consists of no more than one point.

Spectra of the Energy Operator of Two-Electron System in the Impurity Hubbard Model

We consider two-electron systems for the impurity Hubbard Model and investigate the spectrum of the system in a singlet state for the v-dimensional integer valued lattice Zv. We proved the essential spectrum of the system in the singlet state is consists of union of no more then three intervals, and the discrete spectrum of the system in the singlet state is consists of no more then five eigenvalues. We show that the discrete spectrum of the system in the triplet and singlet states differ from each other. In the singlet state the appear additional two eigenvalues. In the triplet state the discrete spectrum of the system can be empty set, or is consists of one-eigenvalue, or is consists of two eigenvalues, or is consists of three eigenvalues. For investigation the structure of essential spectra and discrete spectrum of the energy operator of two-electron systems in an impurity Hubbard model, for which the momentum representation is convenient. In addition, we used the tensor products of Hilbert spaces and tensor products of operators in Hilbert spaces and described the structure of essential spectrum and discrete spectrum of the energy operator of two-electron systems in an impurity Hubbard model.

Structure of Essential Spectra and Discrete Spectrum of the Energy Operator of Six-Electron Systems in the Hubbard Model. First Quintet and First Singlet States

We consider the energy operator of six-electron systems in the Hubbard model and investigate the structure of essential spectra and discrete spectrum of the system in the first quintet and first singlet states in the v-dimensional lattice.

Four-Electron Systems in the Impurity Hubbard Model. Second Triplet State. Spectra of the System in the ν-Dimensional Lattice Zν

We consider an energy operator of four-electron system in the Impurity Hubbard model with a coupling between nearest-neighbors. The spectrum of the systems in the second triplet state in a ν-dimensional lattice is investigated. For investigation the structure of essential spectra and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model, for which the momentum representation is convenient. In addition, we used the tensor products of Hilbert spaces and tensor products of operators in Hilbert spaces and described the structure of essential spectrum and discrete spectrum of the energy operator of four-electron systems in an impurity Hubbard model for the second triplet state of the system. The investigations show that the essential spectrum of the system consists of the union of no more than sixteen segments, and the discrete spectrum of the system consists of no more than eleven eigenvalues.

Effects of donor density and temperature on electron systems in AlGaN/AlN/GaN and AlGaN/GaN structures

It was reported by Shen et al that the two-dimensional electron gas （2DEG） in an AlGaN/AlN/GaN structure showed high density and improved mobility compared with an AlGaN/GaN structure, but the potential of the AlGaN/AlN/GaN structure needs further exploration. By the self-consistent solving of one-dimensional Schroedinger- Poisson equations, theoretical investigation is carried out about the effects of donor density （0-1×10^19 cm^-3） and temperature （50-500 K） on the electron systems in the AlGaN/AlN/GaN and AlGaN/GaN structures. It is found that in the former structure, since the effective △Ec is larger, the efficiency with which the 2DEG absorbs the electrons originating from donor ionization is higher, the resistance to parallel conduction is stronger, and the deterioration of 2DEG mobility is slower as the donor density rises. When temperature rises, the three-dimensional properties of the whole electron system become prominent for both of the structures, but the stability of 2DEG is higher in the former structure, which is also ascribed to the larger effective △Ec. The Capacitance-Voltage （C - V） carrier density profiles at different temperatures are measured for two Schottky diodes on the considered heterostructure samples separately, showing obviously different 2DEG densities. And the temperature-dependent tendency of the experimental curves agrees well with our calculations.

Realizations, Characterizations, and Manipulations of Two-Dimensional Electron Systems Floating above Superfluid Helium Surfaces

Electron systems in low dimensions are enriched with many superior properties for both fundamental research and technical developments. Wide tunability of electron density, high mobility of motion, and feasible controllability in microscales are the most prominent advantages that researchers strive for. Nevertheless, it is always difficult to fulfill all in one solid-state system. Two-dimensional electron systems(2DESs) floating above the superfluid helium surfaces are thought to meet these three requirements simultaneously, ensured by the atomic smoothness of surfaces and the electric neutrality of helium. Here we report our recent work in preparing, characterizing, and manipulating 2DESs on superfluid helium. We realized a tunability of electron density over one order of magnitude and tuned their transport properties by varying electron distribution and measurement frequency. The work we engage in is crucial for advancing research in many-body physics and for development of single-electron quantum devices rooted in these electron systems.

A New Method for Calculations of Two-Electron Systems in Magnetic Field

A method suitable for two-electron systems in a range running from low to high fields is given.ML=-1 triplet state of H-ion and He atom are used to introduce the new means.All the matrix elements in our calculations are formulated as products of simple,independent one-dimensional numerical integrals and analytic ones.As a result,lower energies compared to those obtained with spherical coordinates in low fields,and cylindrical coordinates in high fields are presented.

Correlated-Electron Systems and High-Temperature Superconductivity

We present recent theoretical results on superconductivity in correlated-electron systems, especially in the two-dimensional Hubbard model and the three-band d-p model. The mechanism of superconductivity in high-temperature superconductors has been extensively studied on the basis of various electronic models and also electron-phonon models. In this study, we investigate the properties of superconductivity in correlated-electron systems by using numerical methods such as the variational Monte Carlo method and the quantum Monte Carlomethod. The Hubbard model is one of basic models for strongly correlated electron systems, and is regarded as the model of cuprate high temperature superconductors. The d-p model is more realistic model for cuprates. The superconducting condensation energy obtained by adopting the Gutzwiller ansatz is in reasonable agreement with the condensation energy estimated for YBa2Cu3O7. We show the phase diagram of the ground state using this method. We have further investigated the stability of striped and checkerboard states in the under-doped region. Holes doped in a half-filled square lattice lead to an incommensurate spin and charge density wave. The relationship of the hole density x and incommensurability δ, δ~x, is satisfied in the lower doping region, as indicated by the variationalMonte Carlocalculations for the two-dimensional Hubbard model. A checkerboard-like charge-density modulation with a roughly period has also been observed by scanning tunneling microscopy experiments in Bi2212 and Na-CCOC compounds. We have performed a variational Monte Carlo simulation on a two-dimensional t-t′-t″- U Hubbard model with a Bi-2212 type band structure and found that the period checkerboard spin modulation, that is characterized by multi Q vectors, is indeed stabilized. We have further performed an investigation by using a quantumMonte Carlomethod, which is a numerical method that can be used to simulate the behavior of correlated electron systems. We present a new algorithm of the quantum Monte Carlo diagonalization that is a method for the evaluation of expectation value without the negative sign problem. We compute pair correlation functions and show that pair correlation is indeed enhanced with hole doping.

Highly Elastic,Bioresorbable Polymeric Materials for Stretchable,Transient Electronic Systems

Substrates or encapsulants in soft and stretchable formats are key components for transient,bioresorbable electronic systems;however,elastomeric polymers with desired mechanical and biochemical properties are very limited compared to nontransient counterparts.Here,we introduce a bioresorbable elastomer,poly(glycolide-co-ε-caprolactone)(PGCL),that contains excellent material properties including high elongation-at-break(<1300%),resilience and toughness,and tunable dissolution behaviors.Exploitation of PGCLs as polymer matrices,in combination with conducing polymers,yields stretchable,conductive composites for degradable interconnects,sensors,and actuators,which can reliably function under external strains.Integration of device components with wireless modules demonstrates elastic,transient electronic suture system with on-demand drug delivery for rapid recovery of postsurgical wounds in soft,time-dynamic tissues.

Bioelectronic medicine in modulation of cortical spreading depolarization and beyond

Bioelectronic interventions,specifically trigeminal nerve st imulat ion(TNS),have attracted considerable attention in conditions where cortical spreading depolarizations(CSDs)accompanied by compromised cerebral perfusion may exacerbate neurological damage.While pharmacological interventions have demonstrated initial potential in addressing CSDs,a standardized treatment approach has not yet been established.The objective of this perspective is to explore emerging bioelectronic methodologies for addressing CSDs,particularly emphasizing TNS,and to underscore TNS’s capacity to enhance neurovascular coupling and cerebral perfusion.

Heterogeneity of mature oligodendrocytes in the central nervous system

Mature oligodendrocytes form myelin sheaths that are crucial for the insulation of axons and efficient signal transmission in the central nervous system.Recent evidence has challenged the classical view of the functionally static mature oligodendrocyte and revealed a gamut of dynamic functions such as the ability to modulate neuronal circuitry and provide metabolic support to axons.Despite the recognition of potential heterogeneity in mature oligodendrocyte function,a comprehensive summary of mature oligodendrocyte diversity is lacking.We delve into early 20th-century studies by Robertson and Río-Hortega that laid the foundation for the modern identification of regional and morphological heterogeneity in mature oligodendrocytes.Indeed,recent morphologic and functional studies call into question the long-assumed homogeneity of mature oligodendrocyte function through the identification of distinct subtypes with varying myelination preferences.Furthermore,modern molecular investigations,employing techniques such as single cell/nucleus RNA sequencing,consistently unveil at least six mature oligodendrocyte subpopulations in the human central nervous system that are highly transcriptomically diverse and vary with central nervous system region.Age and disease related mature oligodendrocyte variation denotes the impact of pathological conditions such as multiple sclerosis,Alzheimer's disease,and psychiatric disorders.Nevertheless,caution is warranted when subclassifying mature oligodendrocytes because of the simplification needed to make conclusions about cell identity from temporally confined investigations.Future studies leveraging advanced techniques like spatial transcriptomics and single-cell proteomics promise a more nuanced understanding of mature oligodendrocyte heterogeneity.Such research avenues that precisely evaluate mature oligodendrocyte heterogeneity with care to understand the mitigating influence of species,sex,central nervous system region,age,and disease,hold promise for the development of therapeutic interventions targeting varied central nervous system pathology.

Constructing Donor–Acceptor‑Linked COFs Electrolytes to Regulate Electron Density and Accelerate the Li^(+)Migration in Quasi‑Solid‑State Battery

Regulation the electronic density of solid-state electrolyte by donor–acceptor(D–A)system can achieve highly-selective Li^(+)transportation and conduction in solid-state Li metal batteries.This study reports a high-performance solid-state electrolyte thorough D–A-linked covalent organic frameworks(COFs)based on intramolecular charge transfer interactions.Unlike other reported COFbased solid-state electrolyte,the developed concept with D–A-linked COFs not only achieves electronic modulation to promote highly-selective Li^(+)migration and inhibit Li dendrite,but also offers a crucial opportunity to understand the role of electronic density in solid-state Li metal batteries.The introduced strong electronegativity F-based ligand in COF electrolyte results in highlyselective Li^(+)(transference number 0.83),high ionic conductivity(6.7×10^(-4)S cm^(−1)),excellent cyclic ability(1000 h)in Li metal symmetric cell and high-capacity retention in Li/LiFePO_(4)cell(90.8%for 300 cycles at 5C)than substituted C-and N-based ligands.This is ascribed to outstanding D–A interaction between donor porphyrin and acceptor F atoms,which effectively expedites electron transferring from porphyrin to F-based ligand and enhances Li^(+)kinetics.Consequently,we anticipate that this work creates insight into the strategy for accelerating Li^(+)conduction in high-performance solid-state Li metal batteries through D–A system.

Reform of the Comprehensive Practical Course System for Mechanical and Electronic Engineering Majors Under the Background of New Engineering

Under the background of new engineering,the reform of the comprehensive practical course system for mechanical and electronic engineering majors actively responds to the challenges posed by the new round of technological revolution and industrial transformation to higher education,cultivating top-notch innovative intellectuals with comprehensive engineering qualities,meeting the requirements of being able to solve complex engineering problems rather than just cognitive capabilities,forming two core courses through reconstructing and reshaping the core courses of the major.The core courses include Drive,Measurement,and Control I and Drive,Measurement,and Control II,which highlight the comprehensive framework of mechanical and electronic engineering professional knowledge,continuing the comprehensive practical course system based on the unity of knowledge and practice,following the trend of new engineering,highlighting the practicality of professional innovation,assisting engineering education reform,and promoting high-quality development of new engineering professionals cultivation.

Electronic Reserves System-基于Web的电子教学参考文献服务系统

网络技术的发展使传统的教学参考书服务正在走向数字化 ,这种全新的服务方式将会使高校师生得益匪浅。鉴于我国高校图书馆界正积极着手开展此项服务 ,本文参考了北美目前发展比较成熟的电子教学参考文献服务系统 ,对其系统模式及功能特点进行了分析 ,旨在为我国高校图书馆开展此项工作提供借鉴和参考。

Inverse Halogen Bonds Interactions Involving Br Atom in the Electronic Deficiency Systems of CH3＋… Br-Y （Y--H, CCH, CN, NC）

Inverse halogen bonds interactions involving Br in the electronic deficiency systems of CH3＋...Br-Y （Y=H, CCH, CN, NC） have been investigated by B3LYP/6- 311＋＋G（d, p） and MP2/6-311＋＋G（d, p） methods. The calculated interaction energies with basis set super-position error correction of the four IXBs complexes are 218.87, 219.48, 159.18, and 143.05kJ/mol （MP2/6-311＋＋G（d, p））, respectively. The relative stabilities of the four complexes increased in the order： CH3＋ … BrCN〈CH3＋…- BrNC〈CH3＋… BrH≈CH3＋ …BrCCH. Natural bond orbital theory analysis and the chemical shifts calculation of the related atoms revealed that the charges flow from Br-Y to CH3e. Here, the Br of Br-Y acts as both a halogen bond donor and an electron donor. Therefore, compared with conventional halogen bonds, the IXBs complexes formed between Br-Y and CH3＋. Atoms-in-molecules theory has been used to investigate the topological properties of the critical points of the four IXBs structures which have more covalent content.

Experimental Study of Diesel-NG Dual Fuel Electronic System for F6L912Q Engine

In order to improve the diesel engine emission performance and convert the diesel engine to dual fuel engine, a dual fuel (diesel and compressed natural gas (CNG)) electronic system was developed, in which electromagnetic valves were used to control multi point natural gas injection. The system was designed for type F6L912Q diesel engine and the function of the system was testified on test cell. The test results showed that the system had great advantages in power ability and emission performance. The average CNG substitution at rated load was over 80%. The dual fuel system was practical. To adopt dual fuel system was a good way to improve the engine's emission performance.

The Research and Application of the Anti-Interference Techniques of Electronic Device in Power System

This paper presents the study and application of the electronic device anti-interference techniques underhigh voltage and/or heavy current electro-magnetic circumstance in power system.[

Speed Disturbance in the Diesel Engine Electronic Control System

In order to sample the speed signal of electronic diesel engine in real time and make the engine work reliable, the diesel engine control system's speed acquisition was studied and the problem of speed disturbance was solved. The control system was based on the 8?bit electronic control unit(ECU) system and the assembly language was used to design the software for controlling the engine fuel quantity and the turbocharger of the variable geometry turbine for the heavy duty diesel engine. By changing the timing method for speed acquisition, the problem of speed disturbance was solved and the reliability of the ECU was improved.