Kim Ho Yeap

Digital Image Processing and Analysis for Activated Sludge Wastewater Treatment

Activated sludge system is generally used in wastewater treatment plants for processing domestic influent. Conventionally the activated sludge wastewater treatment is monitored by measuring physico-chemical parameters like total suspended solids (TSSol), sludge volume index (SVI) and chemical oxygen demand (COD) etc. For the measurement, tests are conducted in the laboratory, which take many hours to give the final measurement. Digital image processing and analysis offers a better alternative not only to monitor and characterize the current state of activated sludge but also to predict the future state. The characterization by image processing and analysis is done by correlating the time evolution of parameters extracted by image analysis of floc and filaments with the physico-chemical parameters. This chapter briefly reviews the activated sludge wastewater treatment; and, procedures of image acquisition, preprocessing, segmentation and analysis in the specific context of activated sludge wastewater treatment. In the latter part additional procedures like z-stacking, image stitching are introduced for wastewater image preprocessing, which are not previously used in the context of activated sludge. Different preprocessing and segmentation techniques are proposed, along with the survey of imaging procedures reported in the literature. Finally the image analysis based morphological parameters and correlation of the parameters with regard to monitoring and prediction of activated sludge are discussed. Hence it is observed that image analysis can play a very useful role in the monitoring of activated sludge wastewater treatment plants.

A Simple Method for Calculating Attenuation in Waveguides

We present a simple technique to compute the attenuation of electromagnetic waves propagating in waveguides with imperfect conducting walls. The propagation constant can be computed by numerically solving the transcendental equations, derived from the surface impedance of the walls and substituting the results into the dispersion relation. Good agreements were found between the results obtained using our method and that using StrattonÌs rigorous equation and Kohler and BayerÌs approximate equation, for both circular and rectangular waveguides, respectively. Index Terms – Attenuation, waveguides, propagation constant, surface impedance

A simple data storage system using QR code

Due to its limited data area, QR codes are presently restricted to storing simple text messages. In this paper, we develop a novel method to expand the storage capacity of QR codes. We propose to compress the file first before encoding it into a QR code. Doing so, we would be able to store more complicated files which require more storage capacity. In our study, we show that both monochrome and colour image files, as well as, voice messages in midi format could be encoded to and decoded from the QR codes.

Full Wave Analysis of Normal and Superconducting Microstrip Transmission Lines

We present a full wave analysis to compute the propagation constant of electromagnetic waves traveling in a normal and superconducting microstrip transmission line. The transverse wavenumber in the dielectric substrate is obtained as the root of a set of transcendental equation, derived by matching the tangential fields at the dielectric-conductor and dielectric-air interfaces. The propagation constant can then be obtained by substituting the transverse wavenumber into the dispersion relation. For normal microstrip lines, we found good agreement between our results and those obtained using the quasi-static methods. As compared to some of the available techniques used to calculate loss in superconducting microstrip lines, such as MatickÌs and Yassin-WithingtonÌs method, our method gives higher loss especially in the regime of millimeter and submillimeter wavelengths. Since our method takes into account the superposition of TE and TM modes, we attribute the differences as due to the fringing fieldÌs effect and the existence of the longitudinal field components in our formulation. Index Terms – propagation constant, superconducting microstrip, dispersion relation, submillimeter wavelengths, fringing fieldÌs effect.

Measuring learning outcomes of Bachelor degree program in outcome-based education

Learning outcomes are skill and ability acquired shortly after the conclusion of a learning session, which is typically a 14-week semester in undergraduate engineering degree program. In this report, a 4 year programme offering 130 credit hours is chosen as an example. One of the criteria in Outcome Based Education is the assessment of learning outcomes as achievement indicator for continuous performance quality management. This criterion is driving educators to look for ways to deliver continuous improvement. This paper reports on practical method of assessing the learning outcomes on unit by unit and the contributions to the degree programme learning outcomes.

Segmentation and grading of eczema skin lesions

In this paper Eczema skin lesions are segmented and graded using image processing and analysis. For preprocessing adaptive light compensation and gamma correction has been used. The effect of color space normalization has been studied for lesion segmentation. K-means algorithm is used for segmentation. We have used RGB and CIELab color models; and their normalized I and II versions. The experimental results show that normalized color spaces give better segmentation results than the normal color spaces. Our proposed algorithm gives best segmentation accuracy of 84.6% for RGB normalized II color space for the G channel for adaptive light compensation. The grading accuracy for erythema is around 70%.

Analysis of Probes in a Rectangular Waveguide

Abstract We present an analysis on the performance of wave coupling from a rectangular waveguide to a probe. In order to enable maximum coupling of fields to the probe, we have carefully computed and designed the appropriate height and position of the probe. Comparisons and analysis of the efficiency of wave coupling using coaxial-line and microstrip probes have been performed. The results indicate that the coaxial-line probe is more suitably implemented in the detection of wave in the decimeter band; whereas, the microstrip probe is a better alternative in the coupling of wave in the millimeter band. Such results are very useful, particularly in the detection of the extraterrestrial signal in the field of astrophysics. We have also investigated the fabrication tolerances of both devices. As shown from the results, fabricating a device operating in the millimeter band poses a greater challenge, compared to that in the decimeter band.

Characterization of a submicron PMOS in mixer circuits

In this paper, we investigate the properties of a submicron pMOS with a single layer of metallization. The fabrication process and electrical characterization of the device were simulated using the SILVACO TCAD tools. We have applied constant field scaling on the effective channel length, the density of ion implantation for threshold voltage adjustment, and gate oxide thickness. To suppress short channel effects, we have also applied retrograde well implantation, Shallow Trench Isolation (STI), sidewall spacer deposition, silicide formation, and Lightly Doped Drain implantation in our process simulation. We have validated the electrical performance of the device by plotting and analyzing the ID - Vg relationship

An asymmetric tapered Long Period Fiber Grating: Fabrication and characterization

An asymmetric tapered Long Period Fiber Grating (LPFG) was fabricated using an ignition coil based electric arcing fabrication system. The angle measurement of LPFG imaging using Matlab confirms the asymmetric tapered LPFG formation. Characterization of the asymmetric tapered Long Period Fiber Grating was done to test its sensitivity with respect to changes in the surrounding refractive index and temperature for LPFG at 900 nm to 1000 nm and 1500 nm to 1600 nm wavelength ranges. The fabricated asymmetric tapered LPFG performance is comparable with LPFG fabricated by fusion splicer but with less gratings and higher transmission loss.

Propagation in Lossy Rectangular Waveguides

)In millimeter and submillimeter radio astronomy, waveguide heterodyne receivers are often used in signal mixing. Wave guiding structures such as circular and rectangular waveguides are widely used in such receiver systems to direct and couple extraterrestrial signals at millimeter and submillimeter wavelengths to a mixer circuit (Carter et al., 2004; Boifot et al., 1990; Withington et al., 2003). To illustrate in detail the applications of waveguides in receiver systems, a functional block diagram of a typical heterodyne receiver in radio telescopes is shown in Fig. 1 (Chattopadhyay et al., 2002). The electromagnetic signal (RF signal) from the antenna is directed down to the front end of the receiver system via mirrors and beam waveguides (Paine et al., 1994). At the front end of the receiver system, such as the sideband separating receiver designed for the ALMA band 7 cartridge (Vassilev and Belitsky, 2001a; Vassilev and Belitsky, 2001b; Vassilev et al., 2004), the RF signal is channelled from the aperture of the horn through a circular and subsequently a rectangular waveguide, before being coupled to the mixer. In the mixer circuit, a local oscillator (LO) signal which is generally of lower frequency is then mixed with the RF signal, to down convert the RF signal to a lower intermediate frequency (IF) signal. Here, a superconductor-insulator-superconductor (SIS) heterodyne mixer is commonly implemented for the process of down conversion. At the back end of the system, the IF signal goes through multiple stages of amplification and is, eventually, fed to a data analysis system such as an acousto-optic spectrometer. The data analysis system will then be able to perform Fourier transformation and record spectral information about the input signal. The front-end receiver noise temperature TR is determined by a number of factors. These include the mixer noise temperature TM, the conversion loss CLoss, the noise temperature of the first IF amplifier TIF, and the coupling efficiency between the IF port of the junction and the input port of the first IF amplifier IF  . A comparison of the performance of different SIS waveguide receivers is listed in Table 1 (Walker et al., 1992). It can be seen that the value of TR for the 230 GHz system is a factor of 3 to 4 less than that achieved with the 492 GHz system. The decrease in system performance at 492 GHz is due to the increase of CLoss and TM by a factor of approximately 3.