Packaging a fiber Bragg grating without preloading in a simpleathermal bimaterial device

This study presents two athermal packages for compensating for the temperature deviations in an optical fiber Bragg grating (FBG). Usually, a pre-loading mechanism is necessary in packaging the FBG on bimaterial devices. However, through a unique bonding process design, the pre-loading mechanism in the packaging could be eliminated. During the manufacturing processes, AB thermally cured adhesive is used to affix the FBG to the device under a thermal state. In this way, the FBG affixed to the devices is under tension when the temperature drops to room temperature. The devices can also be placed continuously under a thermal state after a thermal curing process for a pre-determined period of time to perform annealing on the FBG, and thereby, further simplifying the manufacturing process. As a result, the total variation in the Bragg wavelength over the range from -40 to +80°C was around 0.1 nm in the two proposed athermal packages     

Distribution system temperature adaptive load transfer using colored Petri net approach

This paper derives appropriate decisions for load transfer among distribution feeders by switching operations to improve system operating performance by combining the load characteristics and the variations among customers as a result of temperature increases using a switching operation decision inference mechanism based on a colored Petri net (CPN) approach. A practical distribution system with 19 feeders, daily load profiles, and corresponding data on temperature sensitivity (TS) is used to perform computer simulations to demonstrate the effectiveness of the proposed methodology. It is concluded that the proposed CPN inference mechanism can enhance the system operating performance with the proper switching operation by considering the TS of customer power consumption served in each service zone of distribution feeders.     

Protective relay setting of the tie line tripping and load sheddingfor the industrial power system

This paper presents the proper underfrequency relay settings to enhance the operation of industrial power systems with cogeneration facilities. A cogeneration unit was installed in the plant in 1996 to supply the power demand of the plant. The cogeneration unit always faces the shutdown problem when a severe fault occurs on the nearby Taipower network. It is, therefore, necessary to investigate plant protective relay settings to prevent a whole plant blackout when the contingency occurs. A transient stability analysis has been performed by considering both the detailed models of the cogenerators with the governor and exciter control systems and the external utility power system. The underfrequency relay settings for tie line tripping and load shedding are designed to prevent the tripping of the cogeneration units so that the electricity service to the critical loads of the industrial customer can be maintained in case serious external disturbances such as short circuit faults occur. In this study, the scheme of underfrequency relay settings has been developed for the power system of a large synthetic rubber manufacturer with a large cogeneration unit. Three study cases have been selected for the transient stability analysis to verify the effectiveness of the proposed protective relay setting     

A self-regularized approach for rank-deficient systems in the BEM of 2D Laplace problems

The Laplace problem subject to the Dirichlet or Neumann boundary condition in the direct and indirect boundary element methods (BEM) sometimes both may result in a singular or ill-conditioned system (some special situations) for the interior problem. In this paper, the direct and indirect BEMs are revisited to examine the uniqueness of the solution by introducing the Fichera’s idea and the self-regularized technique. In order to construct the complete range of the integral operator in the BEM lacking a constant term in the case of a degenerate scale, the Fichera’s method is provided by adding the constraint and a slack variable to circumvent the problem of degenerate scale. We also revisit the Fredholm alternative theorem by using the singular value decomposition (SVD) in the discrete system and explain why the direct BEM and the indirect BEM are not indeed equivalent in the solution space. According to the relation between the SVD structure and Fichera’s technique, a self-regularized method is proposed in the matrix level to deal with non-unique solutions of the Neumann and Dirichlet problems which contain rigid body mode and degenerate scale, respectively, at the same time. The singularity and proportional influence matrices of 3 by 3 are studied by using the property of the symmetric circulant matrix. Finally, several examples are demonstrated to illustrate the validity and the effectiveness of the self-regularized method.     

A current-controlled oscillator with temperature,voltage, and process compensation

Microsystem Technologies - This paper presents a current-controlled oscillator (CCO) circuit design with temperature, voltage, and process compensation. A current reference biasing circuit...     

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.     

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.     

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.     

Thermal compensation for a chirp fiber Bragg grating bonded substrate

The chirp fiber bragg grating (CFBG) created using the substrate-straining technique requires an invariable center wavelength when subjected to a temperature change. To accomplish this task, a secondary substrate is attached to one side of the main substrate in a bimetallic beam configuration, used as a thermal compensator. However, when the temperature changes, the strain along the CFBG is not uniform because the main substrate is not prismatic. A systematic method based on the shape optimization technique was developed to determine the geometry of the second substrate for temperature compensation. The results show that the second substrate, determined using shape optimization, can produce the required strain distribution to compensate for the center wavelength shift in a CFBG due to temperature changes. Although the thermal compensation of a CFBG demonstrated here is simple, it should be emphasized that this methodology can be easily applied to determine the substrate profile for thermal compensation in other FBG-bonded substrates with nonuniform cross sections.