A scatter model for vegetation up to Ku-band

A scatter model is developed based on the matrix doubling method for volume scattering and the Kirchhoff method in rough surface scattering. Scattering from vegetation is assumed to be dominated by leaves and a single leaf is modeled by a thin dielectric disc. In developing the phase matrix for the disc, field within the disc is taken to be constant over the disc thickness, but phase changes across the surface of the disc are accounted for. Comparisons of this scatter model with radar measurements indicate good agreements in polarization, angular trends, and frequency up to Ku-band. This represents a considerable improvement over low-frequency scatter models which are valid up to S-band.     

Fourier-transform analysis of electrostatic potential distributionthrough a thick slit

A potential distribution through a slit in a thick conducting plane is examined. The Fourier-transform is used to represent the potential in the spectral domain and the boundary conditions are enforced to represent a solution in closed form. The solution is in a rapidly converging series so that it is numerically efficient. The Fourier-transform approach is novel in that it allows one to obtain a simple series solution without recourse to the Schwarz-Christoffel transformation     

Multiple scattering and depolarization by a randomly rough Kirchhoff surface

A matrix approach has been developed to compute bistatic scattering coefficients which include shadowing and multiple scattering effects for a randomly rough Kirchhoff surface. The method permits the computation of these coefficients in terms of the existing single-scatter bistatic scattering coefficients. Thus the effects of multiple scattering are readily recognized from the expressions obtained. The bistatic scattering coefficients are shown to satisfy energy conservation to at least two significant figures. It is observed that while polarized backscattering is dominated by the single-scattering process, the depolarized backscattering is due to multiple scattering. Unlike depolarization by slightly rough surfaces or volume scattering, the angular behavior of the depolarized backscattering is similar to that of the polarized backscattering. The transitional behavior of the relative dominance between single and multiple scattering for the polarized and depolarized scattering coefficient as a function of the azimuth angle is illustrated.     

Novel mobile TFT‐LCDs based on SLS technology

Abstract— Single‐crystal‐like silicon (SLS) technology is the most cost‐effective laser‐crystallization process ever invented. The throughput of the SLS process is about two times higher than that of the conventional excimer‐laser annealing (ELA) method. In addition, the performance of the TFTs fabricated by the SLS process is among the best utilized in mass production. Various TFT‐LCDs employing SLS technology, which included a 1.02‐in. full SOG LCD using an icon display for the sub‐display of cellular phones, a 1.9‐in. qVGA TFT‐LCD with a low‐power analog interface employing a low‐voltage driving scheme, and a 3.0‐in. VGA TFT‐LCD compatible with the 480i data format without additional signal processing were developed. Because the SLS process enables us to achieve highly uniform and reliable transistors, it can be effectively utilized in the mass production of mobile TFT‐LCDs with low power consumption and enhanced image quality.     

Generalized circular autoregressive models for isotropic and anisotropic Gaussian textures

A new class of random field models, called generalized circular autoregressive (GCAR) models, is introduced. GCAR models have noncausal neighbors that have the same autoregressive parameter values if they are on the same circle or ellipse and that have circular or elliptical correlation structures. This model is better for modeling isotropic or anisotropic natural textures than earlier approaches to modeling of isotropic textures and can represent complex textures with a small number of parameters. Parameter estimation is also considered, and a multistep estimation algorithm is presented. Properties of estimators of GCAR models are also investigated. The efficacy of GCAR models in modeling real textures is demonstrated by synthesizing images resembling real textures by use of parameters estimated from textures selected from the Brodatz texture album. Limitations of GCAR models are also discussed.     

Diversity analysis of lactic acid bacteria in Korean rice wines by culture-independent method using PCR-denaturing gradient gel electrophoresis

A polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method was used to determine the presence and diversity of lactic acid bacteria (LAB) in takju, a traditional Korean rice wine. Bacterial DNAs were extracted from 15 commercial rice wines and amplicons of partial 16S rRNA genes were separated by DGGE and intense bands were sequenced. Lactobacillus (Lb.) paracasei, Lb. plantarum, and Leuconostoc pseudomesenteroides were detected in all samples and Lb. harbinensis and Lb. parabuchneri were found with above 80% frequency of occurrence. Unknown species of Lactobacillus were also widely detected. This result revealed that, regardless of products and raw materials, the distribution profiles of LAB in takju products have a common pattern comprising of above predominant species and, furthermore, takju can be regarded as a LAB-rich fermented food providing various probiotics.     

Wavelength-Tunable Broadband Frequency-Domain OCT Source Based on Spatially Filtered Sub-10-fs Pulsed Laser

A wavelength swept broadband source based on a sub-10-femtosecond (fs) pulse laser and a spatial filtering method was developed for the application to frequency-domain optical coherence tomography (FD-OCT). The use of the sub-10-fs laser with a galvano scanner operating at a high repetition rate provided a fast tunable broadband light source, which tuned the spectral component across the spectral bandwidth of 110 nm at 1-kHz repetition rate. The spectrally filtered light beam had 0.5-nm instantaneous spectral linewidths at 1-mW average output power. The implemented FD-OCT system clearly imaged a narrow air gap between glass plates with an axial resolution of 5 mum, which proved a potential for the application of a short pulse laser source to the FD-OCT system. The proposed wavelength swept source scheme can secure mode-hopping-free operation at fast tuning speed, which could be applicable for the FD-OCT system properly.     

Realization of a 594 Wh kg−1 Lithium-Metal Battery Using a Lithium-Free V2O5 Cathode with Enhanced Performances by Nanoarchitecturing

To realize a high-energy lithium metal battery (LMB) using a high-capacity Li-free cathode, in this work, nanoplate-stacked V₂O₅ with dominantly exposed (010) facets and a relatively short [010] length is proposed to be used as a cathode. The V₂O₅ nanostructure can be fabricated via a modified hydrothermal method, including a Li⁺ crystallization inhibitor, followed by heat treatment. In particular, the enlargement of the favorable Li⁺ diffusion pathway in the [010] direction and the formation of a robust hierarchical nanoplate-stacked structure in the modified V₂O₅ improves the electrochemical kinetics and stability; as a result, the nanoplate-stacked V₂O₅ electrode exhibits a higher capacity and rate performance (258 mAh g⁻¹ at 50 mA g⁻¹ [0.17 C], 140 mAh g⁻¹ at 1 A g⁻¹ [3.4 C]) and cycling capability (79% capacity retention after 100 cycles at 0.5 C) compared to the previously reported V₂O₅ nanobelt electrode. Notably, the LMB composed of Li//nanoplate-stacked V₂O₅ full-cells shows high specific energy densities of 594.1 and 296.2 Wh kg⁻¹ at 0.1 and 1.0 C, respectively, and a high Coulombic efficiency of 99.6% during 50 cycles.     

Geometric and Electronic Structural Engineering of Isolated Ni Single Atoms for a Highly Efficient CO2 Electroreduction

Tuning the coordination environment and geometric structures of single atom catalysts is an effective approach for regulating the reaction mechanism and maximize the catalytic efficiency of single-atom centers. Here, a template-based synthesis strategy is proposed for the synthesis of high-density NiN_x sites anchored on the surface of hierarchically porous nitrogen-doped carbon nanofibers (Ni-HPNCFs) with different coordination environments. First-principles calculations and advanced characterization techniques demonstrate that the single Ni atom is strongly coordinated with both pyrrolic and pyridinic N dopants, and that the predominant sites are stabilized by NiN₃ sites. This dual engineering strategy increases the number of active sites and utilization efficiency of each single atom as well as boosts the intrinsic activity of each active site on a single-atom scale. Notably, the Ni-HPNCF catalyst achieves a high CO Faradaic efficiency (FE_CO) of 97% at a potential of −0.7 V, a high CO partial current density (j_CO) of 49.6 mA cm⁻² (−1.0 V), and a remarkable turnover frequency of 24 900 h⁻¹ (−1.0 V) for CO₂ reduction reactions (CO₂RR). Density functional theory calculations show that compared to pyridinic-type NiN_x, the pyrrolic-type NiN₃ moieties display a superior CO₂RR activity over hydrogen evolution reactions, resulting in their superior catalytic activity and selectivity.     

Temporal resolution of the skin impedance measurement in frequency-domain method

The temporal-resolution of the frequency-domain method for the identification of the impedance locus depends on the basis frequency used in the current waveform construction, i.e., the higher basis frequency provides the better temporal resolution. The impedance locus can be characterized by the impedance parameters Z0, beta, and taum. The frequency distribution of limited number of data in the impedance locus would affect the accuracy of the estimated impedance parameters. Therefore, we investigated the relationship between the estimation accuracy of the impedance parameters and the frequency coverage of the impedance locus in relatively low to high impedance conditions (dc impedance Z0= 51 k ohms - 45 M ohms). As the basis frequency, 100 Hz was enough for the usual impedance with Z0 less than 203 k ohms. On the other hand, 10 Hz and 1 Hz were required for the medium-level (Z0 = 517 k ohms), and high-level (Z0 = 45 M ohms) impedance, respectively. The required basis frequency, accordingly the temporal resolution, depended much on the central relaxation time taum which affects the frequency distribution on the impedance locus. The results of this study are expected to serve as the reference of the frequency selection in the frequency-domain analysis of the skin impedance.