Narrow Results

The alignment effect on the L-shell ionization of Nb atom (Z=41) by 0.84MeV, 1.38MeV and 2.92MeV proton impact was investigated. The polarization of L_ℓ X-rays emitted from the aligned niobium target was measured with the crystal spectrometer combined with a position sensitive proportional counter. The experimental values of the degree of alignment A₂ were compared with the prediction of PWBA theory. It results that the experimental value of A₂ in 1.38MeV proton impact was much larger than the theoretical one, and A₂ of 0.84MeV almost coincides with that of 2.92MeV.

The Muon Spectrometer of the ATLAS experiment is a large and complex system relying on several detector technologies. The simulation and reconstruction of muon events require a very careful description of these detectors, some of which provide a muon trigger while the others make precision measurements of tracks. A precise description of the passive materials, toroidal magnet systems and shield is also needed to account for Coulomb scattering and energy losses. Finally, the spectrometer performance is enhanced by the alignment of its precision chambers, so the detector description model must fully implement misalignments and deformations. We present the Detector Description chain employed in the Muon system and its integration in the ATLAS software framework. It relies on a database technology and a standard set of geometrical primitives common to all ATLAS subsystems. The Muon Detector Description has been used successfully in the context of the ATLAS Data Challenges, where it provides a unique and coherent geometry source for the simulation and reconstruction algorithms. It has also been validated in the context of the experimental program of the ATLAS testbeams, where analyses of the treatment of chamber alignment in track reconstruction relies crucially upon the detector description model.

Typically, Bi-Sr-Ca-Cu-O superconductors have a peculiar crystal platelet morphology caused by preferred orientations during crystal growth. Aligned platelets can be formed by reaction between Pb-Bi-O and a ceramic precursor, such as SrCaCu₂O_4+y. The alignment is due to gravitational pull on the liquid phase during sintering. The processing, microstructure and superconducting transport properties of these aligned BSCCO materials have been characterized. Scanning electron microscopy shows that thick, fiber-textured, films grow in single domains. Zero resistivity at 100 K was observed in a textured specimen sintered for 100 hours. With differential thermal analysis, the flux action of lead, which accelerates the kinetics of Bi₂Sr₂Ca₂Cu₃O_10+y formation, is understood.

This paper presents an efficient general purpose search algorithm for alignment and an applied procedure for IC print mark quality inspection. The search algorithm is based on normalized cross-correlation and enhances it with a hierarchical resolution pyramid, dynamic programming, and pixel over-sampling to achieve subpixel accuracy on one or more targets. The general purpose search procedure is robust with respect to linear change of image intensity and thus can be applied to general industrial visual inspection. Accuracy, speed, reliability, and repeatability are all critical for the industrial use. After proper optimization, the proposed procedure was tested on the IC inspection platforms in the Mechanical Industry Research Laboratories (MIRL), Industrial Technology Research Institute (ITRI), Taiwan. The proposed method meets all these criteria and has worked well in field tests on various IC products.

Similarity-based retrieval from shape databases typically employs a pairwise shape matcher and one or more indexing techniques. In this paper, we focus specifically on the design of a pairwise matcher for retrieval of 2-D shape contours. In the past, the matchers used for the one-to-many problem of shape retrieval were often designed for the problem of matching an isolated pair of shapes. This approach fails to exploit two characteristics of the one-to-many matching problem that distinguish it from the one-to-one matching problem. First, the output of shape retrieval systems tends to be dominated by matches to relatively similar shapes. In this paper, we demonstrate that by not expending computational resources on unneeded accuracy of matching, both the speed and the accuracy of retrieval can be increased. Second, the shape database is a large statistical sample of the population of shapes. We introduce a probabilistic model for exploiting that statistical knowledge to further increase retrieval accuracy. The model has several benefits: (1) It does not require class labels on the database shapes, thus supporting unlabeled retrieval. (2) It does not require feature independence. (3) It is parameter-free. (4) It has a fast runtime implementation. The probabilistic model is general and thus potentially applicable to other one-to-many matching problems.

In manifold learning, the neighborhood is often called a patch of the manifold, and the corresponding open set is called the local coordinate of the patch. The so-called alignment is to align the local coordinates in the d-dimensional Euclidean space to get the global coordinate of the manifold. There are two kinds of alignment methods: global and progressive alignment methods. The global alignment methods align the local coordinates of the manifold all at one time by solving an eigenvalue problem. The progressive alignment methods often take the local coordinate of a patch as the basic local coordinate and then attach other local ordinates to the basic local coordinate patch-by-patch until the basic local coordinate evolves into the global coordinate of the manifold. In this paper, a new progressive alignment method is proposed, where only the local coordinates of the two patches with the largest intersection at the current stage of progressive alignment will be aligned into a larger local coordinate. It is inspired by the famous Huffman coding, where two random events with the smallest probabilities at the current phase will be merged into a random event with a larger probability. Therefore, the proposed method is a Huffman-like alignment method. The experiments on benchmark data show that the proposed method outperforms both the global alignment methods and the other progressive alignment methods and is more robust to the changes of data size. The experiments on real-world data show the feasibility of the proposed method.

We consider an Individual-Based Model for self-rotating particles interacting through local alignment and investigate its macroscopic limit. This model describes self-propelled particles moving in the plane and trying to synchronize their rotation motion with their neighbors. It combines the Kuramoto model of synchronization and the Vicsek model of swarm formation. We study the mean-field kinetic and hydrodynamic limits of this system within two different scalings. In the small angular velocity regime, the resulting model is a slight modification of the "Self-Organized Hydrodynamic" model which has been previously introduced by the first author. In the large angular velocity case, a new type of hydrodynamic model is obtained. A preliminary study of the linearized stability is proposed.

We introduce an individual-based model for fiber elements having the ability to cross-link or unlink each other and to align with each other at the cross links. We first formally derive a kinetic model for the fiber and cross-links distribution functions. We then consider the fast linking/unlinking regime in which the model can be reduced to the fiber distribution function only and investigate its diffusion limit. The resulting macroscopic model consists of a system of nonlinear diffusion equations for the fiber density and mean orientation. In the case of a homogeneous fiber density, we show that the model is elliptic.

We study the critical thresholds for the compressible pressureless Euler equations with pairwise attractive or repulsive interaction forces and non-local alignment forces in velocity in one dimension. We provide a complete description for the critical threshold to the system without interaction forces leading to a sharp dichotomy condition between global-in-time existence or finite-time blowup of strong solutions. When the interaction forces are considered, we also give a classification of the critical thresholds according to the different type of interaction forces. We also remark on global-in-time existence when the repulsion is modeled by the isothermal pressure law.

We analyze the one-dimensional pressureless Euler–Poisson equations with linear damping and nonlocal interaction forces. These equations are relevant for modeling collective behavior in mathematical biology. We provide a sharp threshold between the supercritical region with finite-time breakdown and the subcritical region with global-in-time existence of the classical solution. We derive an explicit form of solution in Lagrangian coordinates which enables us to study the time-asymptotic behavior of classical solutions with the initial data in the subcritical region.

The goal of this paper is to study limiting behavior of a self-organized continuous flock evolving according to the 1D hydrodynamic Euler Alignment model. We provide a series of quantitative estimates that show how far the density of the limiting flock is from a uniform distribution. The key quantity that controls density distortion is the entropy ${\mathscr{H}}=\int \rho log\rho \text{d}x$, and the measure of deviation from uniformity is given by a well-known conserved quantity $e=u^{\prime }+{{ℒ}}_{\psi }\rho$, where $u$ is velocity and ${{ℒ}}_{\psi }$ is the communication operator with kernel $\psi$. The cases of Lipschitz, singular geometric, and topological kernels are covered in the study.

We present a stochastic Justh–Krishnaprasad flocking model describing interactions among individuals in a planar domain with their positions and heading angles. The deterministic counterpart of the proposed model describes the formation of nematic alignment in an ensemble of planar particles moving with a unit speed. When the noise is turned off, we show that the nematic alignment state, in which all heading angles are either same or the opposite, is nonlinearly stable using a Lyapunov functional approach. We employed a diameter-like functional via the rearrangement of heading angles in the $2\pi$-interval. In contrast, under the additive noise, a continuous angle configuration will be deviated asymptotically from the nematic state. Nevertheless, in any finite-time interval, we will see that some part of angle configuration will stay close to the nematic state with a positive probability, where we call this phenomenon as stochastic persistency. We provide a quantitative estimate on the probability for stochastic persistency and compare several numerical examples with analytical results.

A systematic investigation of collective properties in the nuclei of an $\alpha$-decay chain from ${}^{216}$Po to ${}^{272}$Cn has been performed in the total-Routhian-surface calculations. The empirical indicator $P$-factor, energy ratio $R_{4/2}=E_{4_1^{+}}/E_{2_1^{+}}$, and the energies of the first excited state $E_{2_1^{+}}$ exhibit a hint about nuclear deformation or shape transition in these nuclei. The calculated results of ground state equilibrium deformations are compared with the previous study and available experimental data, showing a general agreement. In addition, the upbending behaviors in moments of inertia have been reproduced by the present work. It is found that the similar alignment of a neutron $j_{15/2}$ pair is mainly responsible for the upbending in the heavier nuclei. The gentle increasing angular momentums reveal the delayed alignment to certain high spins. Furthermore, taking the near proton drip-line nucleus ${}^{272}$Cn as an example, we briefly discussed the influence of the modification of Woods–Saxon potential parameters (e.g., the strength of the spin-orbit potential $\lambda$ and the nuclear surface diffuseness $a$) on the moment of inertia. This may imply the role of the slight parameter modifications is negligible due to almost unchanged deformation and pairing interactions at ground state.

As the distal radius fracture is one of the most commonly encountered upper limb injuries, the aim of this study was to provide a quick and easy method to aid in the assessment of fractured wrists, both pre- and post-fixation, by utilising the relationship of the radial shaft and the lunate.

A retrospective analysis on 100 consecutive patients with normal wrist radiographs was performed. The results demonstrated that the variations of radiolunate anatomy followed a normal distribution. The normal anatomical relationship was then described.

A second part to the study consisted of reviewing our method of radiocarpal analysis on a cohort of patients who had sustained a distal radius fracture. Carpal alignment pre- and post-fixation was measured, with the results demonstrating that by using this assessment method, it was possible with a quick glance of the radiograph, to determine whether satisfactory correction of the fracture had been achieved.

In a butt-joint coupling system, a fiber is coupled to a slab waveguide by a fiber ended micro-lens (FEML), so that the electromagnetic field emerging from the FEML is completely different from the fiber mode. The conventional method for calculations of the coupling efficiency, such as the overlap integral method, is not valid. In this paper, a Monte Carlo model for the coupling system is proposed, based not only on the principles of reflection and refraction at media interface plane, but also on the diffractions of micro lens. This model incorporates the geometrical surface of both the fiber end-face micro-lens and slab waveguide, the relative position of the fiber and slab waveguide, and also takes into consideration both the aberration and diffraction effects. The propagation characteristics and coupling efficiencies of the system are simulated. The losses caused by misalignment of the system are also discussed.

Objective: Patient-specific positioning guides have been designed to improve precision in total knee arthroplasty. The aim of this study is to evaluate the medium-term clinical and radiological outcomes with magnetic resonance imaging-based patient-specific positioning guides. Material and methods: We retrospectively reviewed patients from two centers treated with total knee arthroplasty performed with patient-specific positioning guides. We enrolled patients operated on between January 2011 and December 2013, with a minimum follow-up of 5 years. Preoperative and postoperative hip knee angle (HKA) and position of each component in the coronal plane were assessed. Overall malalignment was defined as an outlier of more than $3^{\circ }$ from the neutral mechanical axis and specific malalignment as when any component showed more than $2^{\circ }$ of deviation. Clinical outcomes were evaluated using the Hospital for Special Surgery (HSS) knee Score. Results: This study included 68 patients with a mean age of 72 years. The mean postoperative alignment (HKA) was $181.5^{\circ }$ and 26.5% of patients showed coronal malalignment $>3^{\circ }$. Regarding femoral components, 19.1% showed specific malalignment $(>\pm 2^{\circ })$, while 11.7% of tibial components were classified as outliers. The mean HSS Knee Score at final follow up was 89.2. Patients whose implants were mechanically aligned did not obtain better functional outcomes ($p=0.3$). Conclusion: In our series, the use of patient-specific positioning guides resulted in a range of mechanical malalignment, similar to conventional instrumentation results reported in the literature.

Parallel structure is a way to factor out common constituents in the expressions, which makes an effect of simplification of expressions. The complexity can be greatly reduced at the phase of sentence parsing by identifying such boundaries of parallel structure.

In this paper, we propose a probabilistic model to identify parallel cores (corresponding constituents) as well as boundaries of parallel noun phrases conjoined by "wa/gwa" (conjunctive particle in Korean). It is based on the idea of swapping constituents, utilizing symmetry (two or more identical constituents are repeated) and reversibility (the order of constituents is changeable) in parallel structure. The probabilities are calculated from (unlabelled) corpus with parallel structures, which is an advantage over the approaches trained with labeled corpus. Our model, moreover, is not dependent on languages.

It is also shown that the semantic features of the modifiers around parallel noun phrase and the patterns among words can be utilized further to correct the boundaries identified by the swapping model.

Experiment shows that our probabilistic swapping model performs much better than symmetry-based model and machine learning based approaches.

The question how a shared vocabulary can arise in a multi-agent population despite the fact that each agent autonomously invents and acquires words has been solved. The solution is based on alignment: Agents score all associations between words and meanings in their lexicons and update these preference scores based on communicative success. A positive feedback loop between success and use thus arises which causes the spontaneous self-organization of a shared lexicon. The same approach has been proposed for explaining how a population can arrive at a shared grammar, in which we get the same problem of variation because each agent invents and acquires their own grammatical constructions. However, a problem arises if constructions reuse parts that can also exist on their own. This happens particularly when frequent usage patterns, which are based on compositional rules, are stored as such. The problem is how to maintain systematicity. This paper identifies this problem and proposes a solution in the form of multilevel alignment. Multilevel alignment means that the updating of preference scores is not restricted to the constructions that were used in the utterance but also downward and upward in the subsumption hierarchy.

This paper introduces a new method for establishing alignment in systems of collective behavior with degenerate communication protocol. The communication protocol consists of a kernel defining interaction between pairs of agents. Degeneracy presumes that the kernel vanishes in a region, which creates a zone of indifference. A motivating example is the case of a local kernel. Lapses in communication create a lack of coercivity in the energy estimates. Our approach is the construction of a corrector functional that compensates for this lack of coercivity. We obtain a series of new results: unconditional alignment for systems on ${ℝ}^d$ with degeneracy at close range and fat tail in the long range, and for systems on the circle with purely local kernels. The results are proved in the context of both the agent based model and its hydrodynamic counterpart (Euler alignment model). The method covers bounded and singular communication kernels.

Single-walled carbon nanotubes (SWNTs) are grown by thermal chemical vapor deposition at 900°C using methane. Application of an electric field (0.4 V/μm) in situ during the growth process results in directed growth of SWNTs on a horizontal plane bridging a distance as long as 25 μm. This approach is useful in the fabrication of nanotube based transistors.