7,681 research outputs found
Structural relaxation in a system of dumbbell molecules
The interaction-site-density-fluctuation correlators, the dipole-relaxation
functions, and the mean-squared displacements of a system of symmetric
dumbbells of fused hard spheres are calculated for two representative
elongations of the molecules within the mode-coupling theory for the evolution
of glassy dynamics. For large elongations, universal relaxation laws for states
near the glass transition are valid for parameters and time intervals similar
to the ones found for the hard-sphere system. Rotation-translation coupling
leads to an enlarged crossover interval for the mean-squared displacement of
the constituent atoms between the end of the von Schweidler regime and the
beginning of the diffusion process. For small elongations, the superposition
principle for the reorientational -process is violated for parameters
and time intervals of interest for data analysis, and there is a strong
breaking of the coupling of the -relaxation scale for the diffusion
process with that for representative density fluctuations and for dipole
reorientations.Comment: 15 pages, 14 figures, Phys. Rev. E in pres
Active Harmonic Current Elimination and Reactive Power Compensation using Modular Multilevel Cascaded Converter
This paper presents a new application of modular multilevel cascaded converters (MMCC) for combined active harmonic current elimination and reactive power compensation in a power distribution line. A technique for simultaneous extracting harmonic components and reactive element in the load current is presented. A novel voltage control scheme for balancing the module intra-cluster capacitor voltages under distorted load current is incorporated. Simulation studies show the desired performance of the MMCC-based active power conditioning operating under PCC current distortion and varying load conditions
Proton-Antiproton Annihilation in Baryonium
A possible interpretation of the near-threshold enhancement in the
-mass spectrum in is the of existence
of a narrow baryonium resonance X(1860). Mesonic decays of the
-bound state X(1860) due to the nucleon-antinucleon annihilation
are investigated in this paper. Mesonic coherent states with fixed -parity
and -parity have been constructed . The Amado-Cannata-Dedoder-Locher-Shao
formulation(Phys Rev Lett. {\bf 72}, 970 (1994)) is extended to the decays of
the X(1860). By this method, the branch-fraction ratios of , and are calculated. It is shown
that if the X(1860) is a bound state of , the decay channel ( is favored over . In this way, we develop
criteria for distinguishing the baryonium interpretation for the near-threshold
enhancement effects in -mass spectrum in from other possibilities. Experimental checks are expected. An intuitive
picture for our results is discussed.Comment: 19 pages, 3 figure
Single-Pixel Image Reconstruction Based on Block Compressive Sensing and Deep Learning
Single-pixel imaging (SPI) is a novel imaging technique whose working
principle is based on the compressive sensing (CS) theory. In SPI, data is
obtained through a series of compressive measurements and the corresponding
image is reconstructed. Typically, the reconstruction algorithm such as basis
pursuit relies on the sparsity assumption in images. However, recent advances
in deep learning have found its uses in reconstructing CS images. Despite
showing a promising result in simulations, it is often unclear how such an
algorithm can be implemented in an actual SPI setup. In this paper, we
demonstrate the use of deep learning on the reconstruction of SPI images in
conjunction with block compressive sensing (BCS). We also proposed a novel
reconstruction model based on convolutional neural networks that outperforms
other competitive CS reconstruction algorithms. Besides, by incorporating BCS
in our deep learning model, we were able to reconstruct images of any size
above a certain smallest image size. In addition, we show that our model is
capable of reconstructing images obtained from an SPI setup while being priorly
trained on natural images, which can be vastly different from the SPI images.
This opens up opportunity for the feasibility of pretrained deep learning
models for CS reconstructions of images from various domain areas
Origins of ferromagnetism in transition-metal doped Si
We present results of the magnetic, structural and chemical characterizations of Mn<sup>+</sup>-implanted Si displaying <i>n</i>-type semiconducting behavior and ferromagnetic ordering with Curie temperature,T<sub>C</sub> well above room temperature. The temperature-dependent magnetization measured by superconducting quantum device interference (SQUID) from 5 K to 800 K was characterized by three different critical temperatures (T*<sub>C</sub>~45 K, T<sub>C1</sub>~630-650 K and T<sub>C2</sub>~805-825 K). Their origins were investigated using dynamic secondary mass ion spectroscopy (SIMS) and transmission electron microscopy (TEM) techniques, including electron energy loss spectroscopy (EELS), Z-contrast STEM (scanning TEM) imaging and electron diffraction. We provided direct evidences of the presence of a small amount of Fe and Cr impurities which were unintentionally doped into the samples together with the Mn<sup>+</sup> ions, as well as the formation of Mn-rich precipitates embedded in a Mn-poor matrix. The observed T*<sub>C</sub> is attributed to the Mn<sub>4</sub>Si<sub>7</sub> precipitates identified by electron diffraction. Possible origins of and are also discussed. Our findings raise questions regarding the origin of the high ferromagnetism reported in many material systems without a careful chemical analysis
Strengthening local governance arrangements for sanitation: case studies of small cities in Indonesia
Local governments in Indonesia have the primary responsibility for delivering sanitation (wastewater) services. However, in large part due to governance factors, local governments invest little in sanitation services and delivery of services is weak. This research adopted a participatory, case study approach to investigate governance and institutional arrangements for planning, budgeting and implementing sanitation services in small cities and towns in Sumatra, Indonesia. The research focused on the effectiveness of city/regency planning for sanitation, the effectiveness of pokja sanitasi (sanitation committees), the links between planning and investment, and local government roles and responsibilities. This paper presents the findings of three case studies. Barriers to effective delivery of sanitation services include: prescriptive local budgeting and approval systems; lack of local government ownership of assets; and policy, funding and technical arrangements that are biased against strategic delivery
Myxosarcoma in a dwarf hamster (Phodopus sungorus)
A 1.5 years old female Russian dwarf hamster (Phodopus sungorus) was presented with a large mass at right caudal ventral abdomen. Lumpectomy was performed to remove the growth mass and subjected to histopathological examination. The encapsulated mass was 3 cm x 4 cm, grossly solitary, non-ulcerated and pinkish in colour with presence of mucous-like substances on cut surface. Routine histopathology using hematoxylin and eosin staining revealed presence of pleomorphic, loosely arranged stellate to spindle shaped cells, angiogenesis, abundant neutrophils, necrotized tissues and high number of mitotic figures. Tumour tissue was positive for Alcian blue (pH 2.5) stain but negative for Periodic acid-Schiff (PAS) staining which suggests presence of acid mucin which confirmed the diagnosis of myxosarcoma. One month post-surgery, the hamster showed absence for local recurrence of the tumour, but it died a few months later due to unrelated cause
A random quantum key distribution by using Bell states
We proposed a new scheme for quantum key distribution based on entanglement
swapping. By this protocol \QTR{em}{Alice} can securely share a random quantum
key with \QTR{em}{Bob}, without transporting any particle.Comment: Accepted by J. Opt. B: Quantum Semiclass. Op
- …