Highly sensitive and linear calibration optical fiber oxygen sensor based on Pt(II) complex embedded in sol-gel matrix

A simple, low-cost technique for fabrication of high performance optical fiber oxygen sensor is described. An organically modified silicate (ORMOSIL) as a matrix for the fabrication of oxygen sensing film was produced. The technique is based on coating the end of an optical fiber with ORMOSIL composite xerogel films film sequestered with luminophore platinum (II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) prepared by a sol-gel process. The composite xerogels studied are 3,3,3-trifluoropropyltrimethoxysliane (TFP-TriMOS) or n-propyltrimethoxysilane (n-propyl-TriMOS)/tetraethylorthosilane (TEOS)/n-octyltriethoxysilane (Octyl-triEOS). Results show that, expect for PtTFPP-doped TFP-TriMOS or n-propyl-TriMOS/TEOS/Octyl-triEOS composite xerogels show the high sensitivity and linear Stern-Volmer relationship which indicate the homogenous environment of the luminophore. The sensitivities of the two oxygen sensors are quantified in terms of the ratio I_N2/I_O2, where I_N2 and I_O2 represent the detected fluorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental results reveal that the PtTFPP-doped TFP-TriMOS/TEOS/Octyl-triEOS and n-propyl-TriMOS/TEOS/Octyl-triEOS oxygen sensors have sensitivities of 101 and 155, respectively. The experimental results confirm that the current oxygen sensors exhibit the linear Stern-Volmer plots and high-sensitive based on the oxygen indicator embedded in TFP-TriMOS or n-propyl-TriMOS/TEOS/Octyl-triEOS composite xerogels.     

Fluid velocity measurements in a microchannel performed with two new optical heterodyne microscopes

Two laser Doppler microscopes (LDMs) based on an optical heterodyne interferometer have been developed for measuring fluid velocity in a microchannel. One of LDMs receives light from a Zeeman laser, and one easily obtains the standard heterodyne signal because a polarizer is set in front of a photomultiplier tube. The other LDM, with light from a He-Ne laser, employs a diffractive grating as a frequency shifter that is modulated in a sinusoidal movement by a piezoelectric transducer stack. By this modulation the nonstandard heterodyne signal is further processed by a new synthetic heterodyne algorithm. Finally, the phase shift related to the fluid velocity in both LDMs is demodulated by digital postprocessing in fast-Fourier-transform, bandpass filtering, inverse-fast-Fourier-transform, and arctangent algorithms.     

An ecological study of families in transitional housing – ‘housed but not homed’

This article discusses the sense of homelessness among nine homeless families who are in transitional housing in Singapore, where homelessness is minimal and mostly out of the public eye. This study is significant as it investigates homelessness experienced by married couples with children in Singapore, unlike most other research which has examined homelessness among singles or single-parent families, and which is based in Australia, Europe, and the US. The sense of homelessness was shaped by the ecological environment that comprised systemic elements such as kin support, housing policies, and non-housing policies like citizenship, education, welfare, and so forth. Homelessness was seen as (i) a loss of complete autonomy, control, privacy, and comfort; (ii) the lack of physical, practical, and emotional support from kin; (iii) a compromised ‘sense of family’ and family decisions; and (iv) hope and endurance while interacting with the ecological system.     

An ACS-based framework for fuzzy data mining

Data mining is often used to find out interesting and meaningful patterns from huge databases. It may generate different kinds of knowledge such as classification rules, clusters, association rules, and among others. A lot of researches have been proposed about data mining and most of them focused on mining from binary-valued data. Fuzzy data mining was thus proposed to discover fuzzy knowledge from linguistic or quantitative data. Recently, ant colony systems (ACS) have been successfully applied to optimization problems. However, few works have been done on applying ACS to fuzzy data mining. This thesis thus attempts to propose an ACS-based framework for fuzzy data mining. In the framework, the membership functions are first encoded into binary-bits and then fed into the ACS to search for the optimal set of membership functions. The problem is then transformed into a multi-stage graph, with each route representing a possible set of membership functions. When the termination condition is reached, the best membership function set (with the highest fitness value) can then be used to mine fuzzy association rules from a database. At last, experiments are made to make a comparison with other approaches and show the performance of the proposed framework.     

Realization of integrated polarizer and color filters based on subwavelength metallic gratings using a hybrid numerical scheme

This study realizes integrated polarizer and RGB (red, green, and blue) color filters using single- and multiple-layered subwavelength metallic grating structures. A hybrid numerical scheme based on the rigorous coupled-wave analysis method and a genetic algorithm is used to determine the optimal values of the grating period, filling factor, and grating thickness of three different grating structures, namely, a single-layer grating, a double-layer grating, and a double-layer grating with a lateral shift. The optical performance of the various structures is evaluated and compared in terms of the transmission efficiency at the center wavelengths 700.0?nm, 546.1?nm, and 435.8?nm of red, green, and blue light, respectively, and the extinction ratio over the visible wavelength spectrum (380-780?nm). It is shown that the double-layer grating achieves a transmission efficiency of about 50% and an extinction ratio of around 60?dB. Thus, this grating structure provides a convenient and effective means of achieving the polarizing and filtering functions in LCD panels using a single device.     

Learning multiplication through computer-assisted learning activities

This study develops and implements a computer-assisted learning (CAL) program with both multiplicative facts practices and the instruction of meaning behind these facts. The effectiveness of CAL on the development of multiplication abilities is also explored. Eight CAL activities are developed to teach multiplication to second grade elementary school students. The CAL program is comprised of three stages of instruction that addressed in succession the basic concept of multiplication, the meaning and properties of multiplication and multiplication-related computation skills. Evaluation of the effects of the learning activities reveals that CAL activities are effective in improving comprehension of the concept of multiplication and the meaning and properties of multiplication for students who have lower prior knowledge of multiplication, but it does not significantly improve the development of multiplication-related computation skills. Nevertheless, CAL activities facilitate overall learning of multiplication.     

A fast-lock low-power all-digital DLL-based clock generator with fractional multiple technique

Microsystem Technologies - In this paper, a fast-lock low-power all-digital delay-locked-loop (ADDLL)-based clock generator is proposed that generates fractional multiples of a reference frequency....     

A GA-based Fuzzy Mining Approach to Achieve a Trade-off Between Number of Rules and Suitability of Membership Functions

Data mining is most commonly used in attempts to induce association rules from transaction data. Transactions in real-world applications, however, usually consist of quantitative values. This paper thus proposes a fuzzy data-mining algorithm for extracting both association rules and membership functions from quantitative transactions. We present a GA-based framework for finding membership functions suitable for mining problems and then use the final best set of membership functions to mine fuzzy association rules. The fitness of each chromosome is evaluated by the number of large 1-itemsets generated from part of the previously proposed fuzzy mining algorithm and by the suitability of the membership functions. Experimental results also show the effectiveness of the framework.     

New synthetic-heterodyne demodulator for an optical fiberinterferometer

A new algorithm for modulating a PZT stack using a sinewave signal instead of a saw-tooth signal was developed in order to resolve the flyback problem in a PZT driver. An improved synthetic heterodyne demodulator circuit was designed and arranged to interrogate the output signal from an interferometric sensor with a sinewave modulation (phase-generated carrier). The depth of modulation, or a gain amplifier in the circuit design, was adjusted such that the standard heterodyne signal could be formed. The result is a conventional PM-modulated carrier that can be demodulated using standard techniques, followed by a lock-in amplifier or a phase meter, to recover the phase shift in the sensing information. Implementing it into a path-matching differential interferometer for the signal modulation validates this new method. As compared to the conventional technique, modulating the PZT stack in a saw-tooth signal, this technique supplies a wider modulated frequency and, therefore, a wider frequency response in a sensing system. Finally, the new synthetic heterodyne is applied to a differential optical fiber refractometer for measuring the refractive index change. A lock-in amplifier is chosen as the demodulator to extract the phase shift. Therefore, the resolution of this sensing system is 7.52×10^-7 refractive index unit for a 120-μm length of the sensing cavity     

High-Efficiency and Low-Stress ZVT–PWM DC-to-DC Converter for Battery Charger

This work presents a novel highly efficient and low-stress battery charger with a resonant switch converter—based on resonance and zero-voltage-transition soft-switching theory—that reduces defects associated with high voltage and high current stresses caused by the resonance of traditional resonant circuits. The novel battery charger meets the requirement that all circuit components must operate with zero-voltage switching. Experimental test results indicate that the proposed battery charger reduces the temperature of an active power switch, and switching losses are less than those obtained using a traditional pulsewidth-modulation converter as a battery charger.