Optimization technique for the design of a linear optimal powersystem stabilizer

A systematic optimization method for choosing the weighting matrix in linear optimal control system design, under the conditions of prespecified closed-loop dominant eigenvalue locations and feedback gain limit constraints, is presented. With the proposed method the desired weighting matrix can be obtained very quickly and conveniently without the heavy burden of choosing a suitable weighting matrix by trial and error. The analysis shows that a reduced-order feedback controller can be designed with the elements of the weighting matrix chosen in an optimal and coordinated manner. Simulation results of the linear optimal power system stabilizer designed by the proposed optimization technique are also given. The results show the correctness and effectiveness of the proposed method     

Neuropsychological correlates of short-term memory distractor tasks among patients with surgical repair of anterior communicating artery aneurysms.

The relative utility of the visual consonant trigram (VCT) and release from proactive inhibition (PI) versions of the short-term memory (STM) distractor task in investigating the separate but related cognitive realms of memory and executive frontal lobe functioning were explored in patients with anterior communicating artery (ACoA) aneurysms n?=?24. Compared with normal controls n?=?19, ACoA patients were impaired on clinical measures of memory and on measures of executive functioning, including concept formation and fluent word generation. Furthermore, ACoA patients were impaired on the VCT task but not on the release-from PI task, indicating a differential sensitivity of these tasks to the impairment manifested by ACoA patients. Regression modeling indicated that the VCT and release-from-PI tasks were closely associated with clinical memory tests, although the release-from-PI-task was also associated with fluency, an executive functioning domain. In general, our results fail to support the broad generalization that impaired performance on STM distractor tasks is necessarily symptomatic of frontal lobe dysfunction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

N-alkylthioureacadmium (II) complexes as novel precursors for the synthesis of CdS nanoparticles

The cadmium(II) complexes of thiourea and N-alkylthioureas (with alkyl group methyl or ethyl) have been used as precursors for the preparation of TOPO-capped CdS nanoparticles. The precursors are air-stable, easy to prepare and inexpensive. These compounds decompose cleanly to give good quality crystalline materials. The nanoparticles obtained showed quantum confinement effects in their optical spectra and close-to-band-edge emission in luminescence experiments. The broad diffraction patterns and the diffuse rings observed in the SAED patterns are typical of nanometric particles. The TEM images showed agglomerates of needle-like plates of particles. The presence of a strong phosphorus peak in the EDAX spectra is indicative of TOPO bound to the surface.     

A multidimensional scaling analysis of vowel discrimination in humans and monkeys

Multidimensional scaling (MDS) was used to compare perceptual maps for 10 synthetic English vowels in humans and Old World monkeys (Macaca fuscata and Cercopithecus albogularis). Subjects discriminated among the vowels using a repeating background procedure, and reaction times were submitted to an MDS analysis to derive measures of perceive similarity. The dimensions that emerged related to the frequencies of the first (F1), second (F2), and third (F3) formants. Human data indicated a good match to previous MDS studies using rating procedures or confusion matrices: The dominant dimension mapped onto vowel F2, the phonetically most important formant, and the second and third dimensions mapped onto F1 and F3, respectively. For monkeys, equal weightings occurred for F1 and F2, and F3 was not clearly represented. Monkey sensitivity to the formants appeared to relate to formant amplitudes. If monkeys are giving an accurate representation of the psychoacoustic relations among the formants, then our human results suggest that species-specific mechanisms, reflecting the salience of the phonetic feature of advancement, may contribute to vowel coding in humans.     

A clinicopathological study of infections in burn patients and importance of biopsy

Malignant peritoneal mesothelioma is a rare disease. The most frequent initial symptoms are abdominal pain, anorexia, marked weight loss and ascites. Clinical presentation as fever of unknown origin is exceptional. We report three cases diagnosed over a period of twenty years, two cases as fever of unknown origin and the third as prolonged fever. Three patients died within two months after diagnosis and prolonged fever was the clinical manifestation at the onset of the disease. It is important to take malignant peritoneal mesothelioma in the differential diagnosis of fever unknown origin.     

Surface orientation from texture: isotropy or homogeneity (or both)?

We examine two models for human perception of shape from texture, based on two assumptions about the surface texture: isotropy and homogeneity. Observers made orientation judgments on planar textured surfaces. Surface textures were either isotropic or anisotropically stretched or compressed. If subjects used an isotropy assumption, they would make biased orientation estimates for the anisotropic textures. In some conditions some observers showed no bias for the anisotropic textures relative to the isotropic textures. In general, even when the observers showed bias, the biases were significantly less than those predicted if the observer used only deviation from isotropy as a cue. Observers appear to use both the deviation from isotropy and a texture gradient or affine texture distortion cue for shape from texture.