Jones matrix formalism for quasioptical EPR

The Jones matrix formalism that has been used to analyze quasioptical millimeter-wave circuits is extended for specific application to high-frequency electron paramagnetic resonance (EPR). A survey of general expressions for Jones matrices of elements commonly used in quasioptical EPR spectrometers is given. The Jones matrix representations of quasioptical transmission and reflection cavities are derived, and their relationship to the equivalent circuit and transmission line representations used for conventional EPR cavities is demonstrated. The formalism is applied to selected quasioptical EPR spectrometer designs and experimental tests of the formalism are presented for two configurations of a quasioptical spectrometer operating at 220 GHz.     

Transfer matrix method for media with quadratic optical nonlinearity

A transfer matrix method is developed for media containing nonlinear layers. This method can be used to calculate the propagation of light, the electromagnetic field profile, and also second-harmonic generation in layered structures containing a layer exhibiting quadratic nonlinearity. Zh. Tekh. Fiz. 69, 116–117 (April 1999)     

Broadband IF matching for quasioptical mixers

Everyone recognizes the need to drive symmetric quasioptical antennas in a symmetric way to maintain clean antenna patterns; in this note we report on the advantages of bringing out the IF in a symmetric (balanced) way as well. The main difference in IF circuits between waveguide and open structure mixers is that the quasioptical mixers are usually also open at IF wavelengths, so IF currents can flow on the outside of the mixer mounting structures. We measured these surface currents and their associated resonances on a scale model of our mixer block for a 690 GHz SIS mixer. Bringing the IF off the mixer with a balanced circuit solves the surface current problems, yielding a broad bandwidth with predictable impedances. We successfully tested an octave bandwidth IF matching circuit for open structure mixers that incorporates a commercial 180° hybrid at cryogenic temperatures. We also found that surface currents are not significant for corner cube mixers because they generate their own balancing currents.     

光盘阵列系统的一种性能优化方法

提出了一种用低性能驱动器组建高性能光盘阵列系统性能的优化方法。针对传统的低性能光盘驱动器(驱动器内部数据传输率及接口速率均较低),提出了一种新型的数据传输模式。采用此优化方法可以使光盘阵列系统的整体性能得到较大地提高。同时还可以提高系统整体的性价比。     

Geometry projection method for optimizing photonic nanostructures

A geometry projection method for the design of photonic nanostructures is demonstrated and compared with a topology optimization method. By using a higher-dimensional surface to delineate the material interfaces, the projection method restricts the regions of intermediate dielectric properties to a narrow user-defined band and gives some implicit control over feature size. Topology optimization addresses these issues by using a penalization to avoid areas of intermediate dielectric and a filter to obtain implicit control over feature size. The directional emission from a photonic crystal waveguide termination is improved by both methods by generating a series of irregularly shaped dielectric posts. Results are presented, and the relative merits of each method are discussed.     

变厚度圆板、环板振动分析的传递矩阵法*

变厚度圆板和环板是在工程设计中经常遇到的一类构件,与等厚度板相比,通过适当的沿径向厚度的变化,这种变厚度板在振动、失稳、弯曲等方面能起到更好的效果。将沿径向任意变厚度圆板、环板划分为一系列等厚度环板单元,基于Mindlin中厚板理论采用逆向推导的方式推导了其传递矩阵,建立起变厚度圆板、环板的频率方程。通过计算线性变厚度环板自由振动时的频率,并与ANSYS模态分析结果相比较,验证了计算模型的精确性。逆向推导法避免了高阶数传递矩阵推导复杂的问题,是对传递矩阵法的很好推广。     

重入式谐振腔特性参数的解析方法

对于在速调管中广泛使用的重入式谐振腔以及内部无漂移管的盒形腔,在忽略漂移管壁厚的前提下,导出了能够准确求解其谐振频率的本征方程,并在此基础上进一步计算了腔体的特性阻抗和固有品质因数。针对具体算例的应用表明,由解析式确定的腔体特性参数与SUPERFISH的数值结果具有很好的一致性。     

重入式谐振腔特性参数的解析方法

 对于在速调管中广泛使用的重入式谐振腔以及内部无漂移管的盒形腔,在忽略漂移管壁厚的前提下,导出了能够准确求解其谐振频率的本征方程,并在此基础上进一步计算了腔体的特性阻抗和固有品质因数。针对具体算例的应用表明,由解析式确定的腔体特性参数与SUPERFISH的数值结果具有很好的一致性。     

Transfer matrix for the open chain from giant gravitons

We construct the transfer matrix for the open chain with the centrally extended SU(2|2) symmetry attached to the so called Z=0 giant graviton brane. Using the reflection equations, unitarity property and crossing property, we show that this model is integrable.     

Transfer matrix for the open chain from giant gravitons

We construct the transfer matrix for the open chain with the centrally extended SU（2｜2） symmetry attached to the so called Z = 0 giant graviton brane. Using the reflection equations,unitarity property and crossing property,we show that this model is integrable.     

A method for enhancing the resolution of overlapping EPR lines

A simple and fast method for enhancing the resolution of overlapping EPR lines based on the convolution theorem of Fourier analysis is presented. The method provides two analytic expressions in real space by means of which the user can remove, by deconvolution, either a Lorentzian or a Gaussian function from a given experimental spectrum. This method is applied to deconvolve the line-overlapping EPR spectrum of molybdenumphthalocyanine (MoPc) in solution in fuming sulfuric acid. The deconvolved spectrum is then compared with the EPR spectrum of MoPc incorporated in concentrated sulfuric acid where the lines do not extensively overlap. Comparison shows that the method is able to enhance the resolution of the originally masked hyperfine pattern of MoPc in the fuming sulfuric acid spectrum. This method can be easily applied to other spectroscopies.     

传递矩阵法预报时空随机激励下任意薄壳腔体内部噪声

利用结构有限元结合声有限元及边界元方法,建立了任意薄壳腔体弹性壳板振动与内外声场的耦合模型,并计算了激励力与壳板振动和内部声场之间的传递矩阵;湍流边界层脉动压力具有时空随机面激励特性,引入整体形状函数矩阵,进一步推导弹性壳板广义节点力功率谱密度函数矩阵与随机面分布激励力功率谱密度函数的关系,再利用声振耦合传递矩阵,得到弹性壳板振动和内部声场功率谱密度函数与广义节点力功率谱密度函数矩阵的关系,形成随机分布激励下任意薄壳腔体结构振动及内部声场的计算方法。以典型的内外均有声介质且一面为弹性矩形板的矩形腔声振耦合模型为例,计算了弹性壳板振动和内部声场功率谱密度函数,并与解析方法进行了比较,两者基本吻合,偏差分别为1 dB和2 dB左右。传递矩阵法不受腔体结构及其内部区域形状的制约,具有良好的适用性。     

Transfer matrix method for internal noise prediction of an arbitrary shell-cavity structure induced by temporal-spatial random surface excitation

Combining structural finite element method(FEM),acoustic finite element and boundary element methods,a model of elastic shell vibration of an arbitrary shell-cavity structure coupled with internal and external sound fields is built.In addition,the transfer matrices from the excitation force to vibration of the shell and internal sound field are calculated.As the fluctuating pressure of turbulent boundary layer(TBL) is a temporal-spatial random surface excitation,the overall shape function matrix is introduced,and then the relationship between power spectral density matrix of the generalized nodal force of the elastic shell and power spectral density of the temporal-spatial random surface excitation is derived.Utilizing the vibro-acoustic coupled transfer matrix,relationships between the power spectral densities of vibration of the elastic shell/internal sound field and the power spectral density matrix of the generalized nodal force are obtained.Thus,the calculation method of vibration and internal sound field of an arbitrary shell-cavity structure induced by temporal-spatial random surface excitation is established.A typical vibro-acoustic coupled model of a rectangular cavity with acoustic media internally and externally,and with elastic rectangular plate on one side,is taken as example.The vibration of the elastic shell and power spectral density of the internal sound field are calculated and compared with the analytical method.The two results generally agree with the analytical one,with deviations of about 1 dB and 2 dB,respectively.The transfer matrix method has good adaptability which is not restricted by the shell-cavity structure and the shape of the inner region.     

Transfer matrix approach to surface states

The tranfer matrix approach is utilized to study the effect of an impurity states within the framework of the one-dimensional Kronig-Penney model.     

Applicability of the minimum entropy generation method for optimizing thermodynamic cycles

Entropy generation is often used as a figure of merit in thermodynamic cycle optimizations. In this paper, it is shown that the applicability of the minimum entropy generation method to optimizing output power is conditional. The minimum entropy generation rate and the minimum entropy generation number do not correspond to the maximum output power when the total heat into the system of interest is not prescribed. For the cycles whose working medium is heated or cooled by streams with prescribed inlet temperatures and prescribed heat capacity flow rates, it is theoretically proved that both the minimum entropy generation rate and the minimum entropy generation number correspond to the maximum output power when the virtual entropy generation induced by dumping the used streams into the environment is considered. However, the minimum principle of entropy generation is not tenable in the case that the virtual entropy generation is not included, because the total heat into the system of interest is not fixed. An irreversible Carnot cycle and an irreversible Brayton cycle are analysed. The minimum entropy generation rate and the minimum entropy generation number do not correspond to the maximum output power if the heat into the system of interest is not prescribed.     

A new method for the determination of oxygen solubilities by EPR

Free radicals dissolved in oxygen-containing solutions give rise to EPR spectra characterized by very broad lines due to Heisenberg spin exchange. In the method herein proposed oxygen is consumed at a constant rate, within the cavity of an EPR spectrometer, by alkyl radicals generatedin situ by thermal decomposition of an aliphatic azo compound in the presence of a nitroxide probe. The effect of decreasing the oxygen concentration is to reduce the width, and therefore to increase the height of the spectral lines of the nitroxide, which reach a maximum when oxygen has been completely consumed. From the knowledge of the rate of generation of the alkyl radicals, the oxygen solubility in a given solvent can be easily determined.     

On the design of broadband quasioptical systems for submillimeter-wave radio-astronomy receivers

In this paper, we summarize the issues that should be considered when designing broadband quasioptical systems for submillimetre-wave radioastronomy receivers. We cover topics such as bandwidth, cross-talk, truncation, and aberrations, and we argue that it should be possible to manufacture high-efficiency systems that have several octaves of bandwidth. A key feature of the paper is that we use the language of multimode Gaussian optics throughout, and in this way, we emphasize that a receiver is a diffraction-limited imaging system rather than just a collection of components for guiding Gaussian beams. The whole discussion is conducted in terms of a particular system we are constructing for the James Clerk Maxwell Telescope in Hawaii.