The Fibonacci language F-u,F-nu is the set of all Fibonacci words, where the first word and the second word in the Fibonacci sequence are u and nu, respectively. We show that the language F-u,F-nu is context-free free. We also show that F-u,F-nu is not dense if the word u nu contains at least two distinct letters. Let w(i) denote the ith Fibonacci word. When considering the Fibonacci language F-a,F-b for two distinct letters a and b, we show that for k greater than or equal to 2 and 1 less than or equal to i < k, the word w(i)w(i) is not a prefix of the Fibonacci word w(k). We also show that for k greater than or equal to 2, the language F-k = {w(nk) / n greater than or equal to 1} is a code. (C) 2000 Elsevier Science B.V. All rights reserved

The deterioration of indoor air quality because of airborne bacterial consortia is a widespread environmental problem. The main objective of this study is to evaluate the feasibility of applying nanoscale silver-doped titanium dioxide (TiO2) photocatalysis (nano-Ag/TiO2) particles as a photocatalyst to enhance the disinfecting capability of bacterial restraining equipment in a medical nursing institution. A full-scale, on-site study was initiated to test the effectiveness of adding the photocatalyst to various air quality control equipments; that is, fixed full-covering type (FF type), underneath swinging type (US type), and lateral swinging type (LS type). Results from this study indicate that the FF type has the best bacterial restraining rate (81%) as compared with the LS type (66%) and the US type (61%). Similar results are obtained at different heights (90 and 180 cm) of the nursing institutions, revealing that freshly disinfected air is provided regardless of location as long as the air quality control equipment is in operation. The proposed equipment can disinfect air to effectively restrain bacteria as demonstrated on-site in medical nursing institutions; the results will also be for designing integrated, commercialized, large-scale applications in the future.

Abstract.A new oil-pressure Velocity and Displacement Dependent Hydraulic Damper (VDHD) is proposed by adding an additional Relief Valve parallel to the Throttle Valve with a different aperture size. This objective is to obtain an adaptive control by changing the damping coefficient of the VDHD for better control of structural movement during earthquake. In order to simulate its actual energy elimination, a mathematical analysis model is developed based on the Maxwell Model, which is modified by adding a serial friction model and a small damper parallel to the friction model in this study. The mathematical simulated results are compared with the actual energy-dissipating behaviours of this proposed damper. The comparison shows that this proposed mathematical modelling could accurately simulate the relation of force and displacement as well as the relation of force and velocity during the process of energy dissipation. In addition, results of both the laboratory shaking table test and simulation analyses are used to test and verify the seismic reduction performance of this proposed damper. The experimental and simulation results show that in spite of the magnitude of the earthquake, the proposed VDHD device has a superior effect on the control of structural displacement by achieving effective acceleration reduction.

In this article, we focus on the properties of word-paired insertions of languages. We show that the word-paired insertions of discrete dense languages, the set of all d-primitive words, and the set of all primitive words are disjunctive (hence, dense and not regular). The equalities and the intersection-properties concerning word-paired insertions of languages are studied too

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