Robust model-following controller design for LTI systems affected by parametric uncertainties: a design example for aircraft motion

This article addresses the design problem of a robust model-following controller (MFC) which minimises the error between plant controlled output and model output for a linear time-invariant (LTI) plant system affected by parametric uncertainties and an LTI target model. To design such an MFC, a previously proposed MFC scheme, whose applicability has already been demonstrated with flight controller design, is adopted in this article. Our design procedure is as follows: first, a basic MFC is designed using the nominal LTI plant model and the LTI target model while a structured free matrix in the MFC is not assigned; second, model-following performance of the MFC for appropriately defined disturbance input and model input for the parametric uncertain plant model and the LTI target model is minimised using the structured free matrix; and finally, a robust MFC is obtained using the basic MFC and the optimal structured matrix. In the second step, an iterative design method for robust H ₂ controllers for LTI parameter-dependent (LTIPD) systems using parameter-dependent Lyapunov functions (PDLFs), which is also proposed in this article, is applied. Two MFCs for the lateral-directional (L/D) motions of a research aircraft, which has been developed for an in-flight simulator, for two different real aircraft models, i.e. a Boeing 747 model and a Lockheed Jetstar model, are designed and their performance is confirmed via numerical simulations and flight tests.     

Robust H 2 control based on dynamic multipliers

In this article, upper bounds on the worst-case H ₂ performance index relative to structured, feedback perturbations are considered which are based on the minimisation of dual Lagrangean functionals over linearly-parametrised, finite-dimensional classes of dynamic multipliers. It is shown that the minimisation problems in question can be recast as optimisation problems with linear cost functional and Linear matrix inequality (LMI) constraints. An iterative scheme is suggested to generate linearly-parametrised classes of multipliers of increasing dynamic order so that progressively tighter upper bounds can be obtained, as illustrated by two simple numerical examples. Finally, with a view to synthesis procedures based on ‘D–K iterations’ relative to multipliers and controllers, it is shown that the minimisation of the upper-bounds corresponding to given multipliers with respect to linearly-parametrised classes of Youla parameters can also be cast as linear-cost/LMI-constraint problems.     

H.264视频解码的OpenMP并行优化

随着H.264视频格式得到广泛应用,对H.264解码的效率要求越来越高,对JM15.1模型中的H.264解码过程进行了分析.采用共享存储编程的工业标准OpenMP对解码过程进行了并行区的设置.设置私有变量防止数据竞争和调整了负载.解码效率提高了10%左右.     

Fast Motion Estimation Algorithm with Edge Alignment for H.264 Encoder

Image sequences processing and video encoding are extremely time consuming problems. The time complexity of them depends on image contents. This paper presents an estimation of a block motion method for video coding with edge alignment. This method uses blocks of size 4 × 4 and its basic idea is to find motion vector using the edge position in each video coding block. The method finds the motion vectors more accurately and faster than any known classical method that calculates all the possibilities. Our presented algorithm is compared with known classical algorithms using the evaluation function of the peak signal-to-noise ratio. For comparison of the methods we are using parameters such as time, CPU usage, and size of compressed data. The comparison is made on benchmark data in color format YUV. Results of our proposed method are comparable and in some cases better than results of standard classical algorithms.     

RECENT ADVANCES AND FUTURE ASPECTS IN THE LOW-TEMPERATURE CONVERSION OF SATURATED HYDROCARBONS

A brief review on the advances and future aspects in the low-temperature activation of carbon–hydrogen and carbon–carbon bonds in hydrocarbons is presented. Particular attention is given to a catalyst formulation for low-temperature conversion of hydrocarbons. An efficient catalyst design method for low-temperature activation of saturated hydrocarbons has been worked out using metal evaporation techniques. The characteristic property of such catalysts is the presence of metal particles on the surface in an atomically dispersed state. Some of the prepared catalysts cause complete hydrocracking of alkanes and cycloalkanes at 423–463K.     

Improvement of paint adhesion to a polypropylene bumper by plasma treatment

Improvement of the paint adhesion to a polypropylene (PP) bumper has been investigated without using a primer by treating the bumper surface with O₂, H₂O, and acetylene plasmas. All the plasma treatments resulted in an increase of the adhesion strength in dry conditions. The adhesion strength could be increased up to a value comparable to that obtained by applying a primer. The treated surfaces were quite stable for 7 days in air. After exposure to wet conditions, however, the adhesion strengths for both O₂ and H₂O plasma-treated samples decreased significantly, while the adhesion strength for the acetylene plasma-treated sample did not change much.     

A large discrepancy between CPM and ESR defect densities in light-soaked a-Si:H

A large discrepancy between defect densities evaluated by constant photocurrent method (CPM) and electron spin resonance (ESR) is investigated for hydrogenated amorphous silicon (a-Si:H) with various thicknesses in the process of light soaking (LS). It is shown by a computer simulation that the inhomogeneous defect distribution across the film thickness caused by a rather small penetration depth of the white light in the thick film is one of the possible origins of the discrepancy. But various other causes should also bring about the discrepancy, and the problem is still a puzzling one.     

Nanoindentation study of calcium silicate hydrates in concrete produced with effective microorganisms-based bioplasticizer

The mechanical properties of concrete produced with effective microorganisms (EM)-based bioplasticizer are investigated by means of statistical nanoindentation, and compared to the nanomechanical properties of concrete produced with ordinary superplasticizer (SP). The resort to nanoindentation enables to survey the elasticity, hardness and long-term logarithmic relaxation behavior of calcium silicate hydrates (C–S–H) after few minutes only. For each material, a cluster analysis of the experimental results yields groupings of indents likely performed on C–S–H with distinct packing densities. It is found that the addition of EM-based bioplasticizer improves the strength of C–S–H by enhancing the cohesion and friction of solid nanograins, and decreases the absolute rate of long-term relaxation. The statistical analysis of indentation results also suggests that EM-based bioplasticizer inhibits the precipitation of C–S–H of higher density. The findings of this work corroborate the results of a previous study which attributed an increase of homogeneity and a refinement of the crystalline structure of silicate phases to the effect of a biomodifier similar to EM-based bioplasticizer. The improvement of strength properties of C–S–H is also shown to coincide with a gain of compressive strength measured at the macroscale of EM-based concrete.     

Culture and psychotherapy: Toward a hermeneutic approach.

Outlines a hermeneutic model of the self and its relationship to culture based on an integration of the hermeneutic work of M. Heidegger, H. Gadamer, and C. Taylor, and the cultural anthropologist C. Geertz. The author begins by first summarizing a hermeneutic theory of culture. Next, how the reigning Western understanding of the person, ontological individualism, makes it difficult to grasp how thoroughly people are shaped by culture is examined. The author then turns to Heidegger's notion of "being-in-the-world" as an alternative non-Cartesian ontology of the human agent that compliments an interpretive view of culture. Also addressed is Taylor's claim that culture is a moral framework that orients us to the good. The author then explores how the hermeneutic notion of dialogue can provide a framework for engaging with those from different cultural backgrounds. Finally, these concepts are applied to a cross-cultural case study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of drying on early-age morphology of C–S–H as observed in environmental SEM

The morphology of early-age C–S–H, often referred to as outer product or low-density C–S–H, is generally accepted to be fibrillar and forms mainly during the early stages of hydration. This paper reports the effect of drying on the microstructure in young tricalcium silicate paste, which provides insight into the mechanism that leads to the fibrillar morphology. During the first few days after C₃S is mixed with water, the morphology of C–S–H is more affected by drying rate than by relative humidity. This sensitivity is most apparent at partial pressures greater than 85%. During this time, the fibrillar C–S–H product can be suppressed by drying C₃S paste samples very slowly prior to imaging. This approach is interpreted as evidence that this fibrillar morphology, which naturally form over time, grow as tiny colloidal particles that rearrange during the early stages of hydration, leading to well-established larger scale morphologies.