The shape gradient of the least-squares objective functional in optimal shape design problems of radiative heat transfer

Optimal shape design problems of steady-state radiative heat transfer are considered. The optimal shape design problem (in the three-dimensional space) is formulated as an inverse one, i.e., in the form of an operator equation of the first kind with respect to a surface to be optimized. The operator equation is reduced to a minimization problem via a least-squares objective functional. The minimization problem has to be solved numerically. Gradient minimization methods need the gradient of a functional to be minimized. In this paper the shape gradient of the least-squares objective functional is derived with the help of the shape sensitivity analysis and adjoint problem method. In practice a surface to be optimized may be (or, most likely, is to be) given in a parametric form by a finite number of parameters. In this case the objective functional is, in fact, a function in a finite-dimensional space and the shape gradient becomes an ordinary gradient. The gradient of the objective functional, in the case that the surface to be optimized is given in a finite-parametric form, is derived from the shape gradient. A particular case, that a surface to be optimized is a “two-dimensional” polyhedral one, is considered. The technique, developed in the paper, is applied to a synthetic problem of designing a “two-dimensional” radiant enclosure.     

Cavity-Assisted Interaction of Superconducting Charge Qubits: The Role of ac Magnetic Flux

We propose, in analogy with trapped ions, scalable quantum computation schemes with superconducting charge qubits couple to a micro-wave cavity mode. Single-qubit addressing can be achieved and selective qubit-cavity coupling can be effectively controlled by the external magnetic flux, thus gate operations can be selectively performed. During the implementation of a certain (virtual) excitation operation all the qubits and cavity parameters can be chosen to be fixed, the only parameter needs to be tunable is the external magnetic flux. This is a more efficient way of controlling the system dynamics as it is much easier for experimental realization.     

多光谱CCD相机配准的图像校正

通过分析线阵CCD的成像过程,对多光谱CCD相机成像的彩色图像合成方式进行了研究,提出了一种处理方法。通过将各谱段CCD的每个像元信号分别扩展成一个二维像素数组后再进行彩色合成,尝试了利用后期处理的方式校正多光谱相机的配准偏差,改善了相机彩色合成图像的质量。结果表明,这种对CCD信号进行处理的合成方式为空间遥感相机的研制提供了一种技术手段,既能减小配准偏差的影响,同时又能够在不改变相机性能的情况下改善相机输出彩色图像的质量。     

雾灯穿透能力最佳波长的实验确定

黄光用作雾灯是由于相对其他色光灯其穿透能力较强的缘故,但黄光的波长范围约有15nm。介绍了人工造雾方法,说明了干冰不适合于人工造雾的理由。讨论了实验中光波长范围的一些选择因素,详细介绍了实验装置,特别强调了实验装置中的6个要点：即光源的辐射功率要大;单色仪的出入射狭缝要合理且两者宽度应调成一致;会聚透镜的焦距要大;加湿器最后出口的孔必须是方的;真空泵和雾气收集罩的作用;微机控制单色仪波长鼓及测量信号的自动记录。得出LED在用作雾灯时的最佳波长为578nm。     

一种具有深度值的莫尔轮廓图

提出一种具有深度值的莫尔轮廓图。将一称为高标的正圆锥与被测物一起置于粗光栅之后 ,平行光照明 ,远场拍照。在所拍图片上高标的高度值 (已知 )除以高标上的等高线数即可求得相邻等高线的深度值 ,进而直接在莫尔轮廓图上读出任一点到基准点的深度差值     

Nonlinear non-extensive approach for identification of structured information

The problem of separating structured information representing phenomena of differing natures is considered. A structure is assumed to be independent of the others if can be represented in a complementary subspace. When the concomitant subspaces are well separated the problem is readily solvable by a linear technique. Otherwise, the linear approach fails to correctly discriminate the required information. Hence, a non-extensive approach is proposed. The resulting nonlinear technique is shown to be suitable for dealing with cases that cannot be tackled by the linear one.     

Critical analysis of the Colle-Salvetti model for electron correlation in closed shell systems: pair correlations

The Colle-Salvetti functional for electron correlation in closed shell systems is applied to a simple two-electron problem and compared with a variational wavefunction. The correlation hole is found to be too short range. As a result, the model is biased towards regions of large electron density and practically neglects pair correlations that are long range. In addition, the correlation energy per electron is found to be singular at the nucleus. The error from neglecting the single-particle operators is found to be of the order of magnitude of the correlation energy itself. It is concluded that the Colle-Salvetti model predicts inaccurate pair correlations and should be used with great care.     

A new approach to the theory of relativity. II. The general theory of relativity

The considerations of Part I are extended and the experimental data and hypotheses that led to the establishment of the general theory of relativity are analyzed. It is found that one of the fundamental assumptions is that light is propagated homogeneously; i.e., by using arbitrary systems of coordinates, propagation of light can be represented by a homogeneous quadratic form. This is shown to be an assumption that can be verified by experiment, at least in principle. As a result of adding a number of further assumptions to this, the usual formalism of the general theory of relativity can be established. In the above point of view, the general theory of relativity—like any other theory—cannot be built upad hoc, but is built on distinct physical hypotheses, each of which can be subjected to test by experiment.     

On stochastic parameter estimation using data assimilation

Data assimilation-based parameter estimation can be used to deterministically tune forecast models. This work demonstrates that it can also be used to provide parameter distributions for use by stochastic parameterization schemes. While parameter estimation is (theoretically) straightforward to perform, it is not clear how one should physically interpret the parameter values obtained. Structural model inadequacy implies that one should not search for a deterministic “best” set of parameter values, but rather allow the parameter values to change as a function of state; different parameter values will be needed to compensate for the state-dependent variations of realistic model inadequacy. Over time, a distribution of parameter values will be generated and this distribution can be sampled during forecasts. The current work addresses the ability of ensemble-based parameter estimation techniques utilizing a deterministic model to estimate the moments of stochastic parameters. It is shown that when the system of interest is stochastic the expected variability of a stochastic parameter is biased when a deterministic model is employed for parameter estimation. However, this bias is ameliorated through application of the Central Limit Theorem, and good estimates of both the first and second moments of the stochastic parameter can be obtained. It is also shown that the biased variability information can be utilized to construct a hybrid stochastic/deterministic integration scheme that is able to accurately approximate the evolution of the true stochastic system.     

Tomography Methods for Vector Field Study Using Space-Distributed Fiber Optic Sensors with Integral Sensitivity

The problem of tomographic reconstruction of vector physical fields is studied. This problem can be solved by using fiber optic measuring lines (MLs) of special shape. In the case that the ML output signal is proportional to the vector's projection, the ML must be shaped like a narrow loop. This problem can be solved by means of the integral theorem. If an ML output signal is proportional to projection of a vector derivative with respect to ML direction, the ML with a step shape can be used. In this case the potential component of a vector field can be reconstructed. This approach can be applied to research on distributions of electromagnetic, deforming, and other vector fields and can be used for developing systems to monitor vector physical fields.     

Hawking radiation of some black holes via the non-equilibrium Landauer transport model

Recently, Nation et al. confirmed that fluxes of Hawking radiation energy and entropy from a black hole can be regarded as a one-dimensional (1D) non-equilibrium Landauer transport process. Their work can be extended to background space-times with gauge potential. The result shows that the energy flux of charged particles, which is shown to be equal to the energy–momentum tensor flux, contains not only the contribution of thermal flux but also that of particle flux. It is found that the charge can also be transported by the 1D quantum channel. Moreover, the entropy production rate is also investigated, which is shown to be larger than the case without chemical potential.     

Optical detection using photodiodes

Linear photodiode-amplifier combinations will be required for optical communication systems, in particular for those using fibre optics as the transmission medium. The noise performance of photodiode-amplifier combinations is derived and presented, and some parameters affecting photodiode and first stage amplifier design are reviewed. It is shown that, of foreseen devices, silicon JFETs will be quietest as amplifier first stages for base bandwidths of up to 10 MHz, GaAs FETs up to 100 MHz and bipolar transistors will be preferred for broader bandwidths. In tuned applications the JFET is to be preferred up to 8 MHz and GaAs FETs will be the best devices above that frequency.     

Brownian motion in a non-isothermal solid

A general method for evaluating the friction constants of the non-isothermal Fokker-Planck equation is derived in the weak anharmonic-coupling limit for a solid, subject to an assumption that suitable angle-action variables can be found. One contribution is reduced to the solution of an integral equation of the Peierls-Boltzmann type and can be used to calculate the phonon scattering contribution q_p * to the heat of transport of a heavy impurity. The structure of the results for a one-dimensional nearest-neighbour chain, for which suitable angle-action variables can be found, is compared with that for a different theory of q_p * based on the special assuption that crystal momentum can be equated to particle momentum, and is found to be different. It is concluded that this special assumption can be dispensed with if suitable angle-action variables can be found, but to accomplish this for a stable three-dimensional crystal appears very difficult. The results for the one-dimensional model, where such variables are easily found, probably have little relevance to real crystals.     

Dynamic stiffness method for exponentially varying harmonic excitation of continuous systems

The dynamic stiffness method relating the amplitudes of applied forces and responses of a harmonically vibrating continuum has received wide attention. It enables the infinite number of natural modes to be represented by a finite number of nodal co-ordinates for continuous structures of beams and folded plates. However, the method has been applied almost exclusively to harmonic, or periodic, oscillations. This is due mainly to the rather misleading intuition that only harmonic vibrations can be described by solutions with separate time- and space-dependent factors. It is shown here that a much wider class of problem of exponentially varying harmonic excitations can also be analyzed by the dynamic stiffness method. The extension is achieved simply by using complex frequency parameters. The forced response (that is, the part of the response which is independent of the initial conditions) can be obtained directly by solution of linear equations. A single degree of freedom system is considered first, as an illustrative example. It is shown that the present method is equivalent to the usual Duhamel integral method except that integration is completely avoided and the transient effects due to the initial conditions can be considered separately. The method is then applied to undamped straight beam members and is modified so that damped vibration can be covered as well. Distributed loads are then considered and explicit formulae are introduced. Finally, for completeness of presentation, the responses are compared with those obtained by using modal analysis. The method is proved to be equivalent to modal analysis and has the advantages over the latter that (i) integrations in the time variable are completely avoided; (ii) the forced response can be obtained directly; (iii) decomposition into generalized forces is not required; and (iv) the force-response relation is easily visualized.     

可调马赫-泽德干涉仪型NRZ到PRZ全光码型转换器

研制了一种基于光纤型马赫-泽德干涉仪的全光码型转换器.通过对工作温度的控制,实现了NRZ码到PRZ码的转换.分析了实现NRZ到PRZ码型的转换原理,讨论了干涉仪的结构设计.在10 Gb/s和20 Gb/s的码型转换实验中,得到较好的PRZ信号眼图.光谱分析表明,转换后的PRZ码包含了丰富的时钟分量,达到了理想的转换结果.结果表明,这种简单的光纤型非对称马赫-泽德干涉仪可以实现NRZ到PRZ的转换,并可以保持输出结果的稳定性.     

Application of interferometric strain rosette to residual stress measurements

An interferometric strain rosette (ISR) technique is extended to residual stress measurements. The ISR technique is based on diffraction and interference of laser light reflected from three micro-indentations depressed in a specimen surface. Three in-plane strain components between the three micro-indentations can be measured simultaneously. Therefore the ISR enables a determination of two normal and one shear strain components. For many applications, the ISR is superior to a resistance strain rosette due to its short gage length and non-contacting nature. By applying an ISR to a material surface, residual stresses at the location of the ISR can be obtained through measurement of residual strains relieved via hole-drilling. Since the gage length can be as short as 50 μm, the ISR is capable of recording high strain gradients and it allows the strains close to the hole to be measured. The size of the hole can be small and precise location is not required. Since the ISR technique is non-contacting, it may be used to measure residual stresses in hostile environments.     

Impact sounds due to sudden accelerations

Impacting bodies are subjected to large transient accelerations and these accelerations could be a significant source of impact noise. It is shown that the maximum acoustic energy that can be radiated due to the sudden accelerations is related to the kinetic energies of the fluid flows in the vicinity of the bodies before and after the impact. For experimentally realizable impacts of hard spheres, only a small fraction of this maximum energy is actually radiated, and for impacts occurring in real machines, this fraction is likely to be even smaller. Sudden accelerations are thus unlikely to be a major source of impact noise.     

发射光谱分析中一种新光源的探索

本本提出用二氧化碳激光器和高压火花发生器组成的新光源，它可以用来对金属，岩石，矿物等粉末样品，块状样品以及溶液干渣样品进行直接激发，同目前认为比较好的ＩＣＰ比较：１）不需要高纯的氩气，２）样品不同经过化学处理等优点。这样，充分发挥发射光谱分析速度快、分析元素广，成本低等特点。     

ICP－AES法测定“中华多宝”等各类营养口服液中多种元素的方法研究

本文应用ＩＣＰ－ＡＥＳ法同时测定“中华多宝”等各类营养口服液中多种元素。方法简便，快速，只需将样品用配制成１％ＨＣｌ的去离子水稀释，摇匀后即可测定。测定中，选用仪器最佳折衷条件，并采用干扰等效浓度消除光谱干扰。方法的回收率在９５％－１０５％，ＲＳＤ为５％。