陕西省镇安县老鼠沟-水磨沟铅锌矿双频激电异常特征及解释

本次投入的双频激电所圈出的幅频率异常和激电测深异常,较好地反映了矿体的延伸情况,特别是M1异常西段的带状异常,硫化物矿体赋存的可能性极大,是很好的找矿标志区。     

Die Erhöhung des Nutzerkomforts von Fußgängerbrücken mit Massendämpfern am Beispiel des August‐Wilhelm‐Stegs in Oranienburg

Aufgrund ihrer schlanken Bauweise gelten viele Fußgängerbrücken bei personeninduzierten Belastungen als schwingungsanfällig. Die eventuelle Ausstattung einer Brücke mit zusätzlichen Dämpfungsmaßnahmen sollte bereits in der Planungsphase berücksichtigt werden, damit bei Gewissheit, dass Maßnahmen notwendig sind, die Fertigstellung und Eröffnung der Brücke nicht verzögert wird. Im vorliegenden Beitrag wird am Beispiel des August‐Wilhelm‐Stegs in Oranienburg das Vorgehen zwischen Erkennen einer möglichen Schwingungsanfälligkeit, Prüfung der Erforderlichkeit schwingungsdämpfender Maßnahmen, Auslegung und Einbau sowie Überprüfung der Wirksamkeit erläutert. Dabei werden insbesondere die praktischen Aspekte bei der Auslegung der Massendämpfer erläutert. The increasing comfort of footbridges with mass dampers is exemplary shown with the August‐Wilhelm‐Steg in Oranienburg, Germany. Many footbridges are susceptible to pedestrian induced vibrations due to their slender design. Hence, an equipment with additional damping devices on demand should be considered already in the preliminary design phase to avoid unnecessary delays of the erection and opening, if the damping devices are required. In this article the procedure of identifying a potential vibration susceptibility, checking the necessity of damping devices, design and installation as well as checking the working efficiency of them are explained using the example of the August‐Wilhelm‐Steg in Oranienburg. Particular emphasis is laid on the practical aspects when designing tuned mass dampers.     

Cross-phase modulation and population redistribution in a periodic tripod medium

The cross-Kerr effect is studied for two weak beams, probe and trigger, propagating in an atomic medium in a tripod configuration, dressed by a strong standing wave coupling beam in a regime of electromagnetically induced transparency. The nonlinear phase shifts for both transmitted and reflected probe beams induced by the trigger's presence are found to depend on the probe detuning, the control beam's intensity, the relaxation rates and, in particular, on the redistribution of the population among the atomic levels. Such a quantitative analysis indicates that the transmitted and reflected probe beam components and their respective phase shifts can be easily controlled and optimized.     

Tunneling-induced high gain and narrow linewidth of a cavity with an asymmetric quantum-well system

A scheme is proposed for obtaining high gain and narrow linewidth of a cavity with an asymmetric quantum-well system. Due to resonant tunneling, destructive interference for linear absorption leads to a tunneling-induced transparency window which compresses the cavity linewidth; moreover, constructive interference for cross-nonlinear susceptibility occurs, which introduces high gain and large dispersion, and the cavity linewidth is much compressed. In the latter case, the intensity of cavity transmission could be enhanced one order of magnitude larger than that of input field, and its linewidth could be one-seventieth of the empty cavity.     

Application of hierarchical matrices to boundary element methods for elastodynamics based on Green's functions for a horizontally layered halfspace

This paper presents the application of hierarchical matrices to boundary element methods for elastodynamics based on Green's functions for a horizontally layered halfspace. These Green's functions are computed by means of the direct stiffness method; their application avoids meshing of the free surface and the layer interfaces. The effectiveness of the methodology is demonstrated through numerical examples, indicating that a significant reduction of memory and CPU time can be achieved with respect to the classical boundary element method. This allows increasing the problem size by one order of magnitude. The proposed methodology therefore offers perspectives to study large scale problems involving three-dimensional elastodynamic wave propagation in a layered halfspace, with possible applications in seismology and dynamic soil–structure interaction.     

Modeling and fabrication of a piezoelectric vibration‐induced micro power generator

Abstract

In this paper, theoretical and experimental study on a piezoelectric vibration‐induced micro power generator that can convert mechanical vibration energy into electrical energy is presented. The mechanical‐electrical energy conversion mechanism is a voltage between two capacitors, which belong to the mechanical and the piezoelectric equivalent circuits, respectively. To verify the theoretical analysis, two clusters of transducer structures are fabricated. Piezoelectric lead zirconate titanate (PZT) material is chosen to make the energy conversion transducer. The desired shape of the piezoelectric generator with its resonance frequency in accordance with the ambient vibration source is designed by finite element analysis (FEA).

Experimental results show that the maximum output voltages are generated at the first mode resonance frequencies of the structure. The overall conversion efficiency is measured to be 33%. The experimental results coincide with the theoretical analysis.     

Chronic fondaparinux use in a hemodialysis patient with heparin‐induced thrombocytopenia type II and extracorporeal circuit thrombosis—A case report and review of the literature

Heparin‐induced thrombocytopenia (HIT) is a potentially life‐threatening condition that can develop after exposure to unfractionated or low–molecular‐weight heparins. Treatment options appear to be limited in patients on concurrent intermittent hemodialysis. We report the case of an 88‐year‐old man newly initiated on high‐flux hemodialysis who developed HIT and extracorporeal circuit thrombosis after 3 weeks of exposure to unfractionated heparin. Our patient was successfully treated with fondaparinux 2.5 mg subcutaneously three times per week and citrate during dialysis sessions. Antifactor Xa levels were measured on several occasions while receiving fondaparinux.     

Eccentric Loading of Fluorogen with Aggregation‐Induced Emission in PLGA Matrix Increases Nanoparticle Fluorescence Quantum Yield for Targeted Cellular Imaging

A simple strategy is developed to prepare eccentrically or homogeneously loaded nanoparticles (NPs) using poly (DL‐lactide‐co‐glycolide) (PLGA) as the encapsulation matrix in the presence of different amounts of polyvinyl alcohol (PVA) as the emulsifier. Using 2,3‐bis(4‐(phenyl(4‐(1,2,2‐triphenylvinyl)‐phenyl)amino)‐phenyl)‐fumaronitrile (TPETPAFN), a fluorogen with aggregation‐induced emission (AIE) characteristics, as an example, the eccentrically loaded PLGA NPs show increased fluorescence quantum yields (QYs) as compared to the homogeneously loaded ones. Field emission transmission electron microscopy and fluorescence lifetime measurements reveal that the higher QY of the eccentrically loaded NPs is due to the more compact aggregation of AIE fluorogens that restricts intramolecular rotations of phenyl rings, which is able to more effectively block the non‐radiative decay pathways. The eccentrically loaded NPs show far red/near infrared emission with a high fluorescence QY of 34% in aqueous media. In addition, by using poly([lactide‐co‐glycolide]‐b‐folate [ethylene glycol]) (PLGA‐PEG‐folate) as the co‐encapsulation matrix, the obtained NPs are born with surface folic acid groups, which are successfully applied for targeted cellular imaging with good photostability and low cytotoxicity. Moreover, the developed strategy is also demonstrated for inorganic‐component eccentrically or homogeneously loaded PLGA NPs, which facilitates the synthesis of polymer NPs with controlled internal architectures.     

Through-Thickness Texture Gradient in Hot-Rolled 25Mn-2. 5Si-2Al TWIP Steel

 Texture is one of the important factors affecting sheet metal forming performance. The through-thickness texture gradient during the hot-rolling process of twinning induced plasticity (TWIP) steel sheet was investigated using electron backscatter diffraction and X-ray diffraction. With increasing reduction of the TWIP steel, the fraction of ∑1 decreased, whereas the fractions of ∑3, ∑9, and ∑27 increased. During 53% reduction, a similar trend could be found from its surface to the center. The gradients of intensities of the fibers decreased with increasing hot-rolling reduction. The intensities of face-centered cubic (fcc) shear textures E and Y were higher in the center than that at the surface for both reductions. During 20% reduction, the intensity of fcc plain strain texture S orientation increased from the center to the surface.