Narrow Results

Volume and width are two of the most studied ways to measure a body. With the concept of width, natural questions arise on lattice polytopes.

A particular question someone can ask is the maximum width that a lattice polytope can have for arbitrary dimension or which is the finiteness threshold of a hollow lattice polytope. These questions are the main topic of this survey.

Focusing in these concepts have helped to bring new upper bounds in the volume of hollow polytopes with lower bounded width, which lead into new advances in their classification. Some examples are maximal 3-hollow polytopes or empty 4-simplices.

In this survey, we recap all background knowledge regarding this concept and get together all new results that have been published during the recent years. These advances in lattice polytopes may lead to new results in big questions of convex geometry as it is finding new examples or bounds in relation with the Flatness Theorem for convex bodies and polytopes.

A model for nanosecond dry laser cleaning that treats the substrate and particle expansion on a unified basis is proposed. Formulas for the time-dependent thermal expansion of the substrate, valid for temperature-dependent parameters, are derived. Van der Waals adhesion, substrate and particle elasticity, and particle inertia are taken into account for an arbitrary temporal profile of the laser pulse. The characteristic time for the particle on the surface system is deduced. This time is related to the size of the particles as well as the adhesion and elastic constants. Cleaning proceeds in different regimes if die duration of the laser pulse is much shorter or longer than this time. Expressions for cleaning thresholds are provided and compared with experiments on the 248 nm KrF excimer-laser cleaning of Si surfaces from spherical SiO₂ particles with radii between 235 and 2585 nm in vacuum. Discrepancies between the experimental data and theoretical results seem to indicate that nanosecond dry laser cleaning cannot be explained purely on the basis of one-dimensional tiiermal expansion mechanism.

Optical problems, related to the particle on the surface, i.e. optical resonance and near-field effects in laser cleaning are discussed. It is shown that the small transparent particle with size by the order of the wavelength may work as a lens in the near-field region. This permits to focus laser radiation into the area with the sizes, smaller than the radiation wavelength. It leads to 3D effects in surface heating and thermal deformation, which influences the mechanisms of the particle removal.

Nanosecond pulsed laser irradiation is shown to be effective for cleaning contaminant particles as small as 0.3 µm in diameter and a variety of organic/inorganic contaminants from metallic substrates and optical components. In the steam-cleaning approach a micron-thick liquid film is deposited on the surface just before the laser irradiation. Experiments are also done to examine the cleaning of surfaces immersed in liquids. The cleaning threshold and efficiency are investigated for the fundamental, frequency-doubled and frequency-tripled Nd: YAG laser harmonics. The particle removal, rapid phase-change and thin liquid film ablation processes are examined via in-situ non-contact diagnostics.

A new algorithm for speech enhancement based on wavelet shrinkage method is presented in this paper. First, the noisy speech by the Bark-scaled Wavelet Packet (BS-WPD) is decomposed to simulate the human auditory characteristics. Then a new thresholding algorithm which has many advantages over soft and hard thresholdings put forward by D.L. Donoho and I.M. Johnstone is proposed. Simulation results indicate that this new method is very useful and efficient in the process of white noise reduction from speech, and the new thresholding algorithm gives better SNR improvement than other traditional thresholding algorithms.

Texture image segmentation is the first essential and important step of low level vision. The extraction of texture features is a most fundamental problem to texture image segmentation. Many methods for extracting texture features of the image have been proposed, such as statistical features, co-occurrence features, two-dimensional AR features, and fractal based features etc. In this paper, a new method for extracting texture features of the image is proposed. In this method, the gray scale image is first decomposed into a series of binary images by variable thresholds, and then topological features of all of these binary images are computed. Using these topological features as texture features, we apply a pyramid linking with band-pass filter neural networks to segment the texture image into some homogeneous areas. Several experiments on synthetic texture images have been carried out to verify the efficacy of the new method.

We report on a HADES measurement of the strange hadrons K^±, and Λ in the reaction Ar(1.76 A·GeV)+KCl and present an estimate of the remaining fraction of strangeness, corresponding mainly to the Σ^0,± hyperons.

Near threshold pion electroproduction as a function of Q² can be written in terms of new form factors. These new generalized form factors and have been predicted using light cone sum rules in the chiral limit for the reactions ep → eNπ in the Q² 1-10 GeV² range. An experiment at Jefferson Lab has been conducted using the CLAS spectrometer to measure near threshold neutral pion electroproduction as a function of Q². Preliminary cross sections, S-wave multipoles and generalized form factors are presented.

We study an SEIRS epidemic model with an isolation and nonlinear incidence rate function. We have obtained a threshold value R₀ and shown that there is only a disease free equilibrium point when R₀ < 1 and an endemic equilibrium point if R₀ > 1. We have shown that both disease free- and endemic equilibrium point are globally stable.

Through the study of MEMS packaging technology, the quartz tuning fork crystal oscillator is directly capsulated in MEMS vacuum packaged shell and the phase and amplitude comparison circuits are used to measure and monitor the degree of vacuum in the internal cavity of the MEMS package. The resistance welding method for vacuum packaging and the vacuum measurement technologies have been developed to improve the performance of the micromachined quartz tuning fork gyroscopes. The threshold is enhanced about 10 times.

It's quite important to do deburring work well in the process of mechanical piece production. This paper introduces a burr detection system based on machine vision, which can detect the position of the workpieces' burrs. It can improve the efficiency of deburring work. This system not only uses the burr detection algorithm, but also introduces the sorting algorithm of useless contours. By using these two algorithms, the system can remove the interference of errors, which makes it effective.