Rotational invariance as an additional constraint on local realism

Rotational invariance of physical laws is a generally accepted principle. We show that it leads to an additional external constraint on local realistic models of physical phenomena involving measurements of multiparticle spin 1/2 correlations. This new constraint rules out such models even in some situations in which standard Bell inequalities allow for explicit construction of such models. The whole analysis is performed without any additional assumptions on the form of local realistic models.     

系统级封装应用中时谐Maxwell方程大规模计算的求解算法:现状与挑战

系统级封装(SiP)是当前电子学系统设计的主流技术途径,数值模拟是进行系统级封装(SiP)设计的主要手段.由于系统级封装应用特有的复杂性,现有的求解时谐Maxwell方程离散系统的算法面临很大的挑战,成为制约该类应用大规模数值模拟效率的瓶颈.本文综述系统级封装应用时谐Maxwell方程解法器求解算法,针对典型实际模型,...     

Structure and energetics of Si nanocrystals embedded in a-SiO2

We develop realistic models of Si nanocrystals embedded in a-SiO2 using a Monte Carlo approach. The interface structure and its energetics are studied as a function of the nanocrystal size. We find that the low-energy geometries at the interface are Si-O-Si bridge bonds. Remarkably, their fraction strongly declines as the size becomes smaller. Concurrently, the embedding causes substantial deformation in such small nanocrystals. Based on these findings, an alternative explanation is given for the reduced optical gaps in this size regime.     

Jet reconstruction and jet properties at HERA

We discuss jet reconstruction methods with respect to their suitability forep collisions at HERA and study the expected properties of such jets. The results are based on complete event simulation using current models of jet evolution and hadronization in combination with experimentally tested jet algorithms. The effects of calorimeter resolution are illustrated by explicit simulation of the energy profile and fluctuations in a simplified, but realistic detector.     

Comparison between microscopic and phenomenological nuclear pairing calculations

The isospin and density dependent effective pairing interaction is revisited by fitting the neutron gaps from the microscopic calculations for the neutron matter and the symmetric nuclear matter.The neutron pairing gaps for 1S0 channel for asymmetric nuclear matter are obtained from the BCS gap equation with a realistic bare nucleon-nucleon interaction in the Skyrme mean field.It is shown that the neutron gaps obtained from the new effective pairing interaction for the asymmetric nuclear matter are much imp...     

ARE THERE ANY REALISTIC SU(N) GRAND UNIFIED MODELS CONTAIN IHG FRACTIONALLY CHARGED PARTICLES?

We have completed a systematic searching for realistic SU(N) grand particles. unified models containing fractionally charged The principles of constructing realistic models are originated from Georgi's with some changes on account of fractionally charged particles. We conclude that there are not any realistic models containing fractionally charged particles.     

CHARGE AND SPIN GAPS IN THE DIMERIZED HUBBARD MODEL

By using the bosonization and renormalization group methods, we have studied the low energy physical properties in the one-dimensional dimerized Hubbard model. The formation of charge and spin gaps is investigated both for the half-filled electron band and away from the half-filled band. The scaling laws of the charge and spin gaps with the dimerization parameterΔ and the repulsive interaction strength U are obtained.     

基于子孔径拼接法测量高精度反射镜

为了解决高精度光学反射镜的子孔径拼接检测问题,基于最小二乘拟合,依据拼接算法建立数学模型,编制了拼接程序,同时对口径为120 mm的平面反射镜进行了拼接检测。检测中,基于标记点确定子孔径间的相对位置,完成子孔径间的对准。分别基于全口径检测结果与自检验子孔径测试结果对拼接结果进行精度分析。实验结果表明:拼接结果无拼痕,拼接结果与全口径测试结果、自检验子孔径测试结果一致; 拼接结果与全口径面形测试的PV值与RMS值的偏差分别为0.020 与0.002 ,验证了检测的可靠性和准确性。     

Material parameter computation for multi-layered vocal fold models

Today, the prevention and treatment of voice disorders is an ever-increasing health concern. Since many occupations rely on verbal communication, vocal health is necessary just to maintain one's livelihood. Commonly applied models to study vocal fold vibrations and air flow distributions are self sustained physical models of the larynx composed of artificial silicone vocal folds. Choosing appropriate mechanical parameters for these vocal fold models while considering simplifications due to manufacturing restrictions is difficult but crucial for achieving realistic behavior. In the present work, a combination of experimental and numerical approaches to compute material parameters for synthetic vocal fold models is presented. The material parameters are derived from deformation behaviors of excised human larynges. The resulting deformations are used as reference displacements for a tracking functional to be optimized. Material optimization was applied to three-dimensional vocal fold models based on isotropic and transverse-isotropic material laws, considering both a layered model with homogeneous material properties on each layer and an inhomogeneous model. The best results exhibited a transversal-isotropic inhomogeneous (i.e., not producible) model. For the homogeneous model (three layers), the transversal-isotropic material parameters were also computed for each layer yielding deformations similar to the measured human vocal fold deformations.     

New polarimetric signal subspace detectors for SAR processors

Our studies aim at detecting targets embedded in a complex environment for radar applications. This article deals with new polarimetric SAR (synthetic aperture radar) processors based on subspace detectors. These algorithms use models of targets including physical and polarimetric properties of their scattering on the contrary to the isotropic point model that is commonly used. These processors are implemented by computing the corresponding subspaces that contain the relevant responses of the target. We choose for application the detection of targets under forest foliage. The obtained results both on simulated data of realistic targets and real data show the interest of these new processors.     

Letter Change Bias and Local Uniqueness in Optimal Sequence Alignments

Considering two optimally aligned random sequences, we investigate the effect on the alignment score caused by changing a random letter in one of the two sequences. Using this idea in conjunction with large deviations theory, we show that in alignments with a low proportion of gaps the optimal alignment is locally unique in most places with high probability. This has implications in the design of recently pioneered alignment methods that use the local uniqueness as a homology indicator.     

No Statistical-Computational Gap in Spiked Matrix Models with Generative Network Priors

We provide a non-asymptotic analysis of the spiked Wishart and Wigner matrix models with a generative neural network prior. Spiked random matrices have the form of a rank-one signal plus noise and have been used as models for high dimensional Principal Component Analysis (PCA), community detection and synchronization over groups. Depending on the prior imposed on the spike, these models can display a statistical-computational gap between the information theoretically optimal reconstruction error that can be achieved with unbounded computational resources and the sub-optimal performances of currently known polynomial time algorithms. These gaps are believed to be fundamental, as in the emblematic case of Sparse PCA. In stark contrast to such cases, we show that there is no statistical-computational gap under a generative network prior, in which the spike lies on the range of a generative neural network. Specifically, we analyze a gradient descent method for minimizing a nonlinear least squares objective over the range of an expansive-Gaussian neural network and show that it can recover in polynomial time an estimate of the underlying spike with a rate-optimal sample complexity and dependence on the noise level.     

Effect of auditory-nerve response variability on estimates of tuning curves

Near-Poisson variability in auditory-nerve (AN) responses limits the accuracy of automated tuning-curve algorithms. Here, a typical adaptive tuning-curve algorithm was used with a physiologically realistic AN model with and without the inclusion of neural randomness. Response randomness produced variability in Q(10) estimates that was nearly as large as in AN data. Results suggest that it is sufficient for AN models to specify frequency selectivity based on mean Q(10) values at each characteristic frequency (CF). Errors in estimates of CF, which decreased from +/-0.2 octaves at low frequencies to +/-0.05 octaves at high frequencies, are significant for studies of spatiotemporal coding.     

Strain drived band aligment transition of the ferromagnetic VS_2/C_3N van der Waals heterostructure

Exploring two-dimensional(2 D) magnetic heterostructures is essential for future spintronic and optoelectronic devices.Herein,using first-principle calculations,stable ferromagnetic ordering and colorful electronic properties are established by constructing the VS_2/C_3 N van der Waals(vdW) heterostructure.Unlike the semiconductive properties with indirect band gaps in both the VS_2 and C_3 N monolayers,our results indicate that a direct band gap with type-Ⅱ band alignment and p-doping characters are realized in the spin-up channel of the VS_2/C_3 N heterostructure,and a typical type-Ⅲband alignment with a broken-gap in the spin-down channel.Furthermore,the band alignments in the two spin channels can be effectively tuned by applying tensile strain.An interchangement between the type-Ⅱ and type-Ⅲ band alignments occurs in the two spin channels,as the tensile strain increases to 4%.The attractive magnetic properties and the unique band alignments could be useful for prospective applications in the next-generation tunneling devices and spintronic devices.     

Principles of computer simulation of EPR spectra

Computer simulations continue to be important in EPR spectroscopy and improved strategies are needed to make the modelling more realistic. Realistic models should ideally seek to account for all of the fundamental interactions that both underlay the spin Hamiltonian and which determine the lineshapes and linewidths, as well as the field-swept nature of EPR. Whilst it is not always possible to retain all of the fundamental principles in practice, distinction between physical assumptions and mathematical approximations should always be correctly made. Key features which should be found in computer simulation algorithms are outlined.     

A simple consensus algorithm for distributed averaging in random geographical networks

Random geographical networks are realistic models for wireless sensor networks which are used in many applications. Achieving average consensus is very important in sensor networks and the faster the consensus is, the durable the sensors?? life, and thus, the better the performance of the network. In this paper we compared the performance of a number of linear consensus algorithms with application to distributed averaging in random geographical networks. Interestingly, the simplest algorithm ?C where only the degree of receiving nodes is needed for the averaging ?C had the best performance in terms of the consensus time. Furthermore, we proved that the network has guaranteed convergence with this simple algorithm.     

Accurate evaluation of lowest band gaps in ternary locally resonant phononic crystals

Based on a better understanding of the lattice vibration modes, two simple spring--mass models are constructed in order to evaluate the frequencies on both the lower and upper edges of the lowest locally resonant band gaps of the ternary locally resonant phononic crystals. The parameters of the models are given in a reasonable way based on the physical insight into the band gap mechanism. Both the lumped-mass methods and our models are used in the study of the influences of structural and the material parameters on frequencies on both edges of the lowest gaps in the ternary locally resonant phononic crystals. The analytical evaluations with our models and the theoretical predictions with the lumped-mass method are in good agreement with each other. The newly proposed heuristic models are helpful for a better understanding of the locally resonant band gap mechanism, as well as more accurate evaluation of the band edge frequencies.     

A re-examination of the traveling wave interaction

A re-examination of the traveling wave interaction (in the helix traveling wave tube and the free-electron laser) is performed using three-dimensional linear stability analyses for an idealized annular electron beam model in order to investigate the validity of the well-known scaling laws in which the gain varies as the cube (fourth) root of the current when space-charge effects are negligible (dominant). The results indicate that these scaling laws are simplistic generalizations which break down for broad bandwidth interactions, and that the actual variation of the pain, with the current can be more complex. A three-dimensional nonlinear analysis of a free-electron laser using a more realistic electron beam model is also discussed in which these scaling laws are also shown to break down,