Mohd Nadzri Md Reba

Geometric and radiometric evaluation of Razaksat medium-sized aperture camera data

Razaksat, a high-resolution Malaysian remote-sensing satellite, was launched on 14 July 2009. It carries a medium-sized aperture camera (MAC) with one panchromatic and four multispectral bands, of 2.5 and 5 m spatial resolution, respectively. The satellite was placed in a near-equatorial orbit with a low inclination angle of 9° to enable an optimum 14 overpasses per day over the equatorial region (i.e. 9° N to 9° S) as compared to only three daily passes over Malaysia for near-polar orbiting satellites. This article reports on evaluation of the panchromatic and multispectral images of MAC: (i) a geometric evaluation of the panchromatic and multispectral MAC images; (ii) a radiometric evaluation, focusing particularly on the noise level and sharpness of the MAC images; (iii) an evaluation of the MAC panchromatic data for updating planimetric topographic features; and (iv) a classification of MAC multispectral data for land-cover mapping. The noise level within the image set was found to increase with the intensity, while the sharpness of edges tested on the images in all non-homogeneous targets was relatively marginal. However, the outcome of the analysis showed the utility and potential of high-resolution panchromatic and multispectral bands of the Razaksat as stipulated in the system mission for terrain mapping.

A review of geospatial-based urban growth models and modelling initiatives

Abstract The way cities are evolving and expanding has been a challenging issue and several urban growth models were proposed. Most of these models have common objectives but they differ in terms of implementation or theoretical assumptions. Urban growth modelling projects that simulate urban spatial change, across the globe, have been reviewed in this study with a view to providing reference for future urban growth modelling development. The mathematical concepts of the modelling techniques were critically examined for holistic understanding of their key components and also to provide a broad description of the existing urban growth modelling works, which has always been ignored in the literature.

An Experimental Study on Bioclimatic Design of Vertical Greenery Systems in the Tropical Climate

This paper presents the use of bioclimatic design using the vertical greenery system (VGS) for a building. The design refers to the temperature and humidity conditions that make humans comfortable and minimize energy consumption particularly in reducing the urban heat island effect. Using vertical plant in front of the building envelope decreases the surrounding temperature. It shows that lower wind speed and higher humidity on the microclimatic layer are characteristics of a VGS that reduces energy consumption for cooling and heating of buildings. This means that the VGS acts as a wind barrier and verifies the effect of evapotranspiration from plants. In this study, the focus is on living walls and green facades placed independently in front of the inner layer of a building corridor. It aims to regulate the temperature and relative humidity, thus creating a thermal comfort environment. Two vertical greenery systems consisting of a modular living wall and green cable facade were installed at the east-corridor wall along the 3rd floor of a 5-storey building wall in Petaling Jaya, Malaysia. Two series of experiments were carried out for temperature and humidity using a Hobo U12-006. The results showed that the cooling effect of a modular system is higher than a cable system. It implies that the modular design and lush vegetation influence the effectiveness of the VGS.

Biohydrogen Production by Antarctic Psychrotolerant Klebsiella sp. ABZ11

Abstract Lower temperature biohydrogen production has always been attractive, due to the lower energy requirements. However, the slow metabolic rate of psychrotolerant biohydrogen-producing bacteria is a common problem that affects their biohydrogen yield. This study reports on the improved substrate synthesis and biohydrogen productivity by the psychrotolerant Klebsiella sp. strain ABZ11, isolated from Antarctic seawater sample. The isolate was screened for biohydrogen production at 30°C, under facultative anaerobic condition. The isolate is able to ferment glucose, fructose and sucrose with biohydrogen production rate and yield of 0.8 mol/l/h and 3.8 mol/g, respectively at 10 g/l glucose concentration. It also showed 74% carbohydrate uptake and 95% oxygen uptake ability, and a wide growth temperature range with optimum at 37°C. Klebsiella sp. ABZ11 has a short biohydrogen production lag phase, fast substrate uptake and is able to tolerate the presence of oxygen in the culture medium. Thus, the isolate has a potential to be used for lower temperature biohydrogen production process.

Evaluation of empirical radar rainfall model during the massive flood in Malaysia

Accurate rainfall estimation from radar reflectivity is crucial in hydrological modeling and quantitative precipitation estimation. Various rainfall intensities exhibited by different rainfall drop size distribution contribute to reflectivity and rain rate relationship (Z-R) variability in radar rainfall estimation. This paper focuses to evaluate the Z-R model during the massive flood in December 2014 for different rainfall intensity. Hourly reflectivity and rain gauge data were used. Linear and non-linear least square regression were applied to compare the accuracy of Z-R coefficients (a and b). This study found that the non-linear least square gives the best evaluation of a and b estimates in high intensity rainfall and Kelantan was experiencing frequent high intensity rainfall during the massive flood in December 2014. Evaluation of empirical model demonstrated in this study can improve the accuracy of radar rainfall estimation.