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基于ANSYS对CFETR真空室简化模型进行了2D/3D电磁分析,得到了真空室磁场强度以及电磁力的分布.分析结果显示2D/3D真空室的磁场强度及电磁力分布基本一致,这表明了可以使用2D模型替代3D模型对未来真空室简化模型进行电磁分析.     

Fourth-generation signatures in D0-;D̄0 mixing and rare D decays

We study the effects of a fourth generation on D⁰-D̄⁰ mixing and the rare decays D⁰→μ⁺μ⁻, D→ℓ⁺ℓ ⁻X (where X is nonstrange), D→πℓ⁺ℓ⁻ and D→ϱγ (orωγ). D⁰-D̄⁰ mixing can be as large as the experimental limit of 0.5%. The fourth generation can enhance the branching ratios for the rare decays by several orders of magnitude: it can be as large as 10⁻⁹ for the decays D⁰→μ⁺μ⁻, D→ℓ⁺ℓ⁻X and D→πℓ⁺ℓ⁻. The long-distance contribution to the radiative decays is estimated to be ∼ 10⁻⁸ and is shown to be dominant in the three-generation model. The fourth generation can bring this branching ratio up to ∼ 10⁻⁶.     

2D/3D CFETR真空室电磁计算

基于ANSYS对CFETR真空室简化模型进行了2D/3D电磁分析,得到了真空室磁场强度以及电磁力的分布。分析结果显示2D/3D真空室的磁场强度及电磁力分布基本一致,这表明了可以使用2D模型替代3D模型对未来真空室简化模型进行电磁分析。     

A note on statistical model for BPS D4–D2–D0 states

We construct a statistical model that reproduces the BPS partition function of D4–D2–D0 bound states on a class of toric Calabi–Yau three-folds. The Calabi–Yau three-folds we consider are obtained by adding a compact two-cycle to _AN−1-ALE×C$A_{N-1}\text{-ALE}\times \mathbb{C}$. We show that in the small radii limit of the Calabi–Yau the D4–D2–D0 partition function is correctly reproduced by counting the number of triangles and parallelograms.     

Momentum-carrying waves on D1–D5 microstate geometries

If one attempts to add momentum-carrying waves to a black string then the solution develops a singularity at the horizon; this is a manifestation of the ‘no hair theorem’ for black objects. However individual microstates of a black string do not have a horizon, and so the above theorem does not apply. We construct a perturbation that adds momentum to a family of microstates of the extremal D1–D5 string. This perturbation is analogous to the ‘singleton’ mode localized at the boundary of AdS; to leading order it is pure gauge in the AdS interior of the geometry.     

D0–D6 States Counting and GW Invariants

We describe a correspondence between the Donaldson?CThomas invariants enumerating D0?CD6 bound states on a Calabi?CYau 3-fold and certain Gromov?CWitten invariants counting rational curves in a family of blowups of weighted projective planes. This is a variation on a correspondence found by Gross?CPandharipande, with D0?CD6 bound states replacing representations of generalised Kronecker quivers. We build on a small part of the theories developed by Joyce?CSong and Kontsevich?CSoibelman for wall-crossing formulae and by Gross?CPandharipande?CSiebert for factorisations in the tropical vertex group. Along the way we write down an explicit formula for the BPS state counts which arise up to rank 3 and prove their integrality. We also compare with previous ??noncommutative DT invariants?? computations in the physics literature.     

用~3He→D核反应分析Ti中的D

用D-~3He核反应分析法分析中发生器用TiD_(?)靶中D的含量x.并利用Au-Si面垒探测器测量了质子能谱,获得了该探测器的灵敏层参量,仔细研究了半导体探测器对高能质子的响应.对质子射程同耗尽层厚度相当时的质子能谱进行的理论计算与实验现象一致. 关键词：     

D波段功率放大器设计

基于0.13 m SiGe BiCMOS工艺, 研究和设计了一种D波段功率放大器芯片。该放大器芯片用了四个功率放大器单元和两个T型结网络构成。功率放大器单元采用了三级的cascode电路结构。低损耗的片上T型结网络既能起到片上功率合成/分配的功能, 又能对输入输出进行阻抗匹配。对电路结构进行了设计、流片验证和测试。采用微组装工艺将该芯片封装成为波导模块。小信号测试结果表明:该功放芯片工作频率为125~150 GHz, 最高增益在131 GHz为21 dB, 最低增益在150 GHz为17 dB, 通带内S22小于-7 dB, S11小于-10 dB。大信号测试结果表明:该功放模块在128~146 GHz带内输出功率都大于13 dBm, 在139 GHz时, 具有最高输出功率为13.6 dBm, 且1 dB压缩功率为12.9 dBm。     

Radiation effect of neutrons produced by D–D side reactions on a D–3He fusion reactor

One of the most important characteristics in D–³He fusion reactors is neutron production via D–D side reactions. The neutrons can activate structural material, degrading them and ultimately converting them into high-level radioactive waste, while it is really costly and difficult to remove them. The neutrons from a fusion reactor could also be used to make weapons-grade nuclear material, rendering such types of fusion reactors a serious proliferation hazard. A related problem is the presence of radioactive elements such as tritium in D–³He plasma, either as fuel for or as products of the nuclear reactions; substantial quantities of radioactive elements would not only pose a general health risk, but tritium in particular would also be another proliferation hazard. The problems of neutron radiation and radioactive element production are especially interconnected because both would result from the D–D side reaction. Therefore, the presentation approach for reducing neutrons via D–D nuclear side reactions in a D–³He fusion reactor is very important. For doing this research, energy losses and neutron power fraction in D–³He fusion reactors are investigated. Calculations show neutrons produced by the D–D nuclear side reaction could be reduced by changing to a more ³He-rich fuel mixture, but then the bremsstrahlung power loss fraction would increase in the D–³He fusion reactor.     

D=2 and D=4 realization of κ-conformal algebra

We describe the generators of-conformal transformations leaving invariant the-deformed d'Alembert equation. For the case D=4 the algebraic structure of the conformal extension of the off-shell spin zero realization of-Poincaré algebra is discussed. Then the D=2 off-shell realization of-conformal algebra for arbitrary spin and its commutation relations are studied.Presented at the 4th Colloquium Quantum Groups and Integrable Systems, Prague, 22–24 June 1995.Supported by KBN grant 2P 302 087 06.     

Na6团簇2D和3D结构的竞争

在距离相关紧密结合分子动力学模型的基础上，对Ｎａ６两个最低能量异构体（一个具有Ｃ５ｖ对称性，是３Ｄ结构，另一个具有Ｄ３ｈ对称性，是２Ｄ结构）的结构性质进行了研究。通过求解Ｈｅｓｉａｎ矩阵和对距离相关紧密结合分子动力学轨道所作的速度自关联函数的福里叶变换分析，得到了这些钠原子微团簇的振动频率。尽管这两种结构的能量很接近，但它们表现出完全不同的振动性质，这反映了其几何结构的差别。     

自制AppleⅡA/D、D/A卡

在联机状态下微机应用于物理实验常常要将各种物理系统经过适当的传感器转换成模拟电压,然后经过模数转换器 ADC 转换成数字量输入计算机进行分析处理.计算机输出的信息也需要经过数模转换器 DAC 将数字量转换成模拟电压以便送到示波器显示或控制其他仪器.本文介绍两种用于 Apple Ⅱ     

Development of Intrinsic Room-Temperature 2D Ferromagnetic Crystals for 2D Spintronics

Two-dimensional(2D) ferromagnetic crystals with fascinating optical and electrical properties are crucial for nanotechnology and have a wide variety of applications in spintronics. However, low Curie temperatures of most 2D ferromagnetic crystals seriously hinder their practical applications, thus searching for intrinsic roomtemperature 2D ferromagnetic crystals is of great importance for development of information technology. Fortunately, progresses have been achieved in the last few years. Her...     

D介子稀有衰变研究

利用工作在北京正负电子对撞机(BEPC)上的北京谱仪(BES)收集到的33pb^－1的Ψ(3770)数据,寻找D介子味道改变中性流(FCNC)和轻子数不守恒(LNV)的稀有衰变, 包括4个D⁰介子的衰变模式(K⁰e⁺e^－,Φe⁺e^－,ρ⁰e⁺e^－和K^*0e⁺e^－)和6个D⁺介子的衰变模式(K^－e⁺e⁺,K⁺e⁺e^－,π^－e⁺e⁺, π⁺e⁺e^－,K^*－e⁺e⁺和K^*+e⁺e^－). 没有发现信号,给出90%置信水平的上限. 其中, D⁺介子的两个衰变模式D⁺→K^*－e⁺e⁺和D⁺→K^*+e⁺e^－的上限是首次测量.     

Spin polarization effect in 2D and Q2D electron gas

We use the constructed spin-dependent static local field functions to calculate the plasmon dispersion of two dimensional spin polarized electron gas (2D SPEG) over a range of electron densities at arbitrarily spin polarization. We also investigate how the finite width of electron layer will affect the plasmon frequency and inverse static dielectric function of 2D SPEG. Our results show that the effect of finite thickness on plasmon dispersion and inverse dielectric function becomes considerable even at high densities in 2D SPEG.