A microstrip wideband monopole antenna for multisystem integration by utilizing stepped‐impedance structure and L‐shaped slot

In this article, a coplanar‐waveguide (CPW)‐fed dual‐band antenna for applications of the multisystem integration has been demonstrated. The resonance analysis of the stepped‐impedance (SI) monopole is presented by using the transmission‐line analysis method. The frequency‐response characteristics of the SI‐monopole, such as the resonance condition and harmonic response, are systematically summarized. Furthermore, utilizing several simple techniques, such as bent feeding topology, asymmetric ground plane, and an L‐shaped slot etched in the ground plane, a right‐hand circularly polarized (RHCP) radiating wave at 1.57 GHz and a left‐hand circularly polarized (LHCP) radiating wave at 2.33 GHz are excited for the applications of the global positioning system (GPS) and the satellite digital audio radio (SDAR) service system. After optimization of the geometrical parameters of the proposed antenna, the measured impedance bandwidths of a reflection coefficient less than ?10 dB range from 1.40 to 2.98 GHz and from 4.48 to 6.27 GHz, and thus covers most of the commercial wireless communication systems, such as GPS, digital cellular system (DCS), personal communication system (PCS), international mobile telecommunications (IMT)?2000, wireless local area networks (WLAN), and long‐term evolution (LTE) 2300/2600. The measured 3‐dB axial ratio (AR) bandwidths are about 80 MHz at 1.57 GHz and 100 MHz at 2.33 GHz.     

Comparison of image reconstruction by using near‐field and far‐field data for an imperfect conductor

Image reconstruction by using near‐field and far‐field data for an imperfectly conducting cylinder is investigated. A conducting cylinder of unknown shape and conductivity scatters the incident wave in free space and the scattered near and far fields are measured. By using measured fields, the imaging problem is reformulated into an optimization problem and solved by the genetic algorithm. Numerical results show that the convergence speed and final reconstructed results by using near‐field data are better than those obtained by using far‐field data. This work provides both comparative and quantitative information. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 69–73, 2001.     

Casper: space exploration through continuous planning

The most interesting places can often be the most dangerous ones, and space exploration is no exception. The dynamic surfaces of comets, the turbulent atmospheres of the gas giants, and the hypothesized subsurface ocean of Europa all call for exploration, and are all very risky for on-site robotic explorers. The Casper (continuous activity, scheduling, planning, execution, and replanning) software system provides critical reasoning capabilities to robotic explorers. To show how it works, we first describe Casper's internal workings and then look at the Three Corner Sat and the Autonomous Sciencecraft Constellation missions, highlighting Casper's contributions to each.     

Adaptive Bayesian Latent Semantic Analysis

Due to the vast growth of data collections, the statistical document modeling has become increasingly important in language processing areas. Probabilistic latent semantic analysis (PLSA) is a popular approach whereby the semantics and statistics can be effectively captured for modeling. However, PLSA is highly sensitive to task domain, which is continuously changing in real-world documents. In this paper, a novel Bayesian PLSA framework is presented. We focus on exploiting the incremental learning algorithm for solving the updating problem of new domain articles. This algorithm is developed to improve document modeling by incrementally extracting up-to-date latent semantic information to match the changing domains at run time. By adequately representing the priors of PLSA parameters using Dirichlet densities, the posterior densities belong to the same distribution so that a reproducible prior/posterior mechanism is activated for incremental learning from constantly accumulated documents. An incremental PLSA algorithm is constructed to accomplish the parameter estimation as well as the hyperparameter updating. Compared to standard PLSA using maximum likelihood estimate, the proposed approach is capable of performing dynamic document indexing and modeling. We also present the maximum a posteriori PLSA for corrective training. Experiments on information retrieval and document categorization demonstrate the superiority of using Bayesian PLSA methods.     

Ultrastructure of nerve plexus in flatworms. III. The infra-epithelial nervous system

In addition to a submuscular and subepithelial nerve plexus an infra-epithelial nerve-net also occurs in Notoplana acticola. It contains naked nerve cells which lie between the bases of epithelial cells. Individual neurites occur separately or in small tracts. Synapses contain clear spherical vesicles and are polarized. Post-synaptic neurites tend to be flat and ribbon-like. Rhabdite and mucus secreting cells in the epithelium have synapses associated with them. Neurites ending on the rhabdites appear to originate in the subepithelial plexus. The "sensory-free nerve endings" of earlier workers are reinterpreted as being motor terminals on epithelial secretory cells.     

Evaluating the quality of airport service using the fuzzy multi‐criteria decision‐making method: a case study of Taiwanese airports

In today's highly competitive air transportation environment, the quality of airport service is an important issue. In this paper, we present a fuzzy multi‐criteria decision‐making (MCDM) method for the evaluation of the quality of airport service. The data are collected from the passengers who depart from two international airports in Taiwan. The fuzzy MCDM model is defuzzied using the inverse function arithmetic representation method. The results show that the average quality of the Taoyuan International Airport service is better than that of the Kaohsiung International Airport service. This paper also analyses the quality of airport service using the fuzzy expert system to improve the performance of airport service. The analysis results show that the Kaohsiung International Airport and the Taoyuan International Airports' improvement efforts should be concentrated on seven and five specific service items, respectively. The findings of this paper are to help the decision‐makers and the managers of airports improve the quality of airport service.     

Mini–max regret strategy for robust capacity expansion decisions in semiconductor manufacturing

Semiconductor manufacturing is capital intensive and the capacity utilization significantly affects the capital effectiveness and profitability of semiconductor manufacturing companies. Semiconductor companies have to rely on various demand forecasts of the products fabricated by different technologies as a basis to determine capital investments for capacity expansion plans that require long-lead time. Moving into the consumer electronics era, semiconductor products have increasingly shortened product life cycles with demand fluctuation. However, given the involved uncertainties and long lead-time for capacity expansion, the capacity expansion decisions of semiconductor manufacturing companies are under both the risks of capacity shortage and surplus along with the time. This study aims to propose a mini?Cmax regret strategy for capacity planning under demand uncertainty to improve capacity utilization and capital effectiveness in semiconductor manufacturing. This model considers each of possible outcomes of the multi-period demand forecasts from sales and marketing departments to generate robust capacity expansion plan to minimize the maximum regrets of capacity oversupply and shortage. An empirical study was conducted in a leading semiconductor company in Taiwan for the validation. The results have shown robustness and practical viability of the proposed mini?Cmax strategy for capacity expansion planning under demand uncertainties.     

Synthesis and optical properties of ordered 30 nm PbS nanowire arrays fabricated into sulfuric anodic alumina membrane

Crystalline PbS nanowire arrays have been successfully fabricated by AC applied DC electrochemical deposition from aqueous solutions of dimethylsulfoxide DMSO solution containing lead chloride and elemental sulfur into sulfuric anodic alumina membranes (AAM). These nanowires have uniform diameters of approximately 30 nm, and their lengths are up to tens of micrometers. Scanning electron microscopy indicates that the ordered PbS nanowire arrays are completely embedded. The results of X-ray diffraction show that the as-synthesized nanowires are crystalline with highly preferential orientation. Energy dispersive spectrometer analysis shows that the composition ratio is very close to 1:1. Finally PL and UV–VIS illustrate the quantum confinement effects of PbS nanowire arrays.     

An all-optical 2R regenerator using a compact self-seeded Fabry-Pe/spl acute/rot laser diode incorporated in a bidirectional EDFA

An all-optical 2R regenerator, based on a compact self-seeded Fabry-Pe/spl acute/rot laser diode with a 10-mm-long embedded fiber Bragg grating cavity, and a bidirectional erbium-doped fiber amplifier, is proposed and experimentally demonstrated to execute all-optical 2R regeneration at 10 Gb/s. Compared with the conventional 1R regeneration, the proposed scheme has achieved significant 6.4-dB improvement of power penalty at bit-error ratio =10/sup -9/ in the transmission experiment over 100-km standard single-mode fiber.     

Image reconstruction of a buried perfectly conducting cylinder illuminated by transverse electric waves

This article presents a computational approach to the image reconstruction of a perfectly conducting cylinder illuminated by transverse electric waves. A perfectly conducting cylinder of unknown shape buried in one half‐space and scatters the incident wave from another half‐space where the scattered field is recorded. Based on the boundary condition and the measured scattered field, a set of nonlinear integral equations is derived, and the imaging problem is reformulated into an optimization problem. The steady state genetic algorithm is then employed to find out the global extreme solution of the cost function. Numerical results demonstrated that, even when the initial guess is far away from the exact one, good reconstruction can be obtained. In such a case, the gradient‐based methods often get trapped in a local extreme. In addition, the effect of different noise on the reconstruction is investigated. © 2006 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15, 261–265, 2005