7,148 research outputs found

    Active force control of 3-RRR planar parallel manipulator

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    This paper presents a new and novel method to control a 3-RRR (revolute-revolute-revolute) planar parallel manipulator using an active force control (AFC) strategy. A traditional proportional-integral-derivative (PID) controller was first designed and developed to demonstrate the basic and stable response of the manipulator in performing trajectory tracking tasks. Later, the AFC section was incorporated into the control scheme in cascade form by adding it in series with the PID controller (PID+AFC), its primary aim of which is to improve the overall system dynamic performance particularly when the manipulator is subjected to different loading conditions. Results clearly illustrate the robustness and effectiveness of the proposed AFC-based scheme in rejecting the disturbances compared to the traditional PID controller

    Measurement of single event upsets in the ALICE-TPC front-end electronics

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    The Time Projection Chamber of the ALICE experiment at the CERN Large Hadron Collider features highly integrated on-detector read-out electronics. It is following the general trend of high energy physics experiments by placing the front-end electronics as close to the detector as possible -- only some 10 cm away from its active volume. Being located close to the beams and the interaction region, the electronics is subject to a moderate radiation load, which allowed us to use commercial off-the-shelf components. However, they needed to be selected and qualified carefully for radiation hardness and means had to be taken to protect their functionality against soft errors, i.e. single event upsets. Here we report on the first measurements of LHC induced radiation effects on ALICE front-end electronics and on how they attest to expectations

    Ergonomic Consideration of the Effect of Flour Dust on Peak Expiratory Flow Rate of Bakers in Abeokuta, Ogun State

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    Flour dusts are one of the most harmful chemicals in the bakery industries which could lead to serious heart and lung diseases. This study investigated the effect of flour dust on Peak Expiratory Flow Rate of male bakers in Abeokuta, Ogun State, Nigeria with the relationship to the anthropometrical parameters. A total of One hundred Eighty (180) male participants were investigated, where ninety (90) participants were bakers and ninety (90) individuals as control group. The Peak expiratory flow rate (PEFR) and anthropometrical parameters of the participant were measured using mini-Wright peak flow meter (PFM 20, OMRON) and Detecto PD300MDHR (Cardinal Scale manufacturing company, USA) column scale with digital height rod was used to measure body mass [kg] and height (cm) respectively. The PEFR and anthropometrical parameters of the bakers and control groups were analysed using descriptive statistics and T-test with SPSS. The results showed that lower PEFR, 182.67 ± 16.34 L/min existed in bakers compared to 287.67 ± 17.02 L/min in the control study. The result also showed that a significant correlation exist between body mass, height and age (P < 0.01), PEFR, height (P < 0.05) and years of exposure (P < 0.01) of the bakers respectively. Furthermore, the results also showed that workers in the dusting and mixing of flour are at a risk of developing related pulmonary function impairment such as asthma. The study concluded that there is need to develop an effective intervention strategy, treatment seeking behaviour through awareness programs to prevent lung impairment diseases among the bakery workers

    Low-cost multimode waveguide couplers for multimode fiber-based local area networks

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    Novel, ultra-compact multimode fiber-matched integrated optical 1×2, 1×3 and 2×2 couplers with low excess losses and large tolerances have been designed and simulated using a fully three-dimensional beam propagation metho

    Starfruit classification based on linear hue computation

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    In this paper, a classification process to group starfruit into six maturity indices is proposed based on 1- dimensional color feature called hue, which is extracted from the starfruit image. As the original hue is quantified from the nonlinear transformation of the 3-dimensional Red, Green and Blue color, this paper proposes a linear hue transformation computation based on the 2 colors of Red and Green. The proposed hue computation leads to a reduced computational burden, less computational complexity and better class discriminant capability. The hue is then applied as the input for the maturity classification process. The classification process is based on the hypothesis that for each of the maturity index, certain area of the starfruit surface is supposed to have distinctive value of the hue. In this work, the said starfruit surface area is set as 70% of the total area and based on 600 samples, the proposed technique results in 93% classification accuracy

    Fabrication of Polymeric Multimode Waveguides and Devices in SU-8 Photoresist Using Selective Polymerization.

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    Large cross section multimode waveguides have been realized in SU-8 using selective polymerization. SU-8 is a negative photoresist, which has shown good optical properties and it is mechanically and chemically stable. The fabricated waveguides have very smooth sidewalls and exhibit low optical losses. The fabrication method is simple and potentially very cost effective. N x N and 1 x N multimode power splitters have been realized using this fabrication technology

    Fabrication of Polymeric Multimode Waveguides for Application in the Local Area Network and Optical Interconnects.

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    We report the fabrication of multimode polymeric waveguides using spin coating, photolithography, and reactive ion etching. Different layer structures have been used, e.g., a UV curable resin is used as a core layer and PMMA as a lower and upper cladding. The layer systems can be spun with good uniformity with thicknesses matching multimode fiber dimensions, and smooth waveguide side-walls have been obtained after etching. The measured performance of these waveguides demonstrates that low-loss waveguides can be fabricated cheaply. The waveguides are used in the realization of novel compact multimode power splitters and star couplers

    Knowledge Discovery in Online Repositories: A Text Mining Approach

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    Before the advent of the Internet, the newspapers were the prominent instrument of mobilization for independence and political struggles. Since independence in Nigeria, the political class has adopted newspapers as a medium of Political Competition and Communication. Consequently, most political information exists in unstructured form and hence the need to tap into it using text mining algorithm. This paper implements a text mining algorithm on some unstructured data format in some newspapers. The algorithm involves the following natural language processing techniques: tokenization, text filtering and refinement. As a follow-up to the natural language techniques, association rule mining technique of data mining is used to extract knowledge using the Modified Generating Association Rules based on Weighting scheme (GARW). The main contributions of the technique are that it integrates information retrieval scheme (Term Frequency Inverse Document Frequency) (for keyword/feature selection that automatically selects the most discriminative keywords for use in association rules generation) with Data Mining technique for association rules discovery. The program is applied to Pre-Election information gotten from the website of the Nigerian Guardian newspaper. The extracted association rules contained important features and described the informative news included in the documents collection when related to the concluded 2007 presidential election. The system presented useful information that could help sanitize the polity as well as protect the nascent democracy