The procedure for selecting values of Manning n is subjective and requires judgment and skill which are developed primarily through experience. Government agencies and private sectors in developed nations such as the USA are still doing research on predicting n values for rivers. Since flow and boundary roughness vary with river conditions, such research is therefore pertinent for rivers in Malaysia where floods are one of primary concerns. Research on Manning n value was started by River Engineering and Urban Drainage Research Centre (REDAC), Universiti Sains Malaysia (USM) since 2000 at the Kinta River catchment. Further data collections were later made at two other major rivers i.e. Langat River and Kulim River. Two new equations are proposed for determining Manning n for sand-bed rivers in Malaysia based on 163 data collected from these three rivers. On average, both equations have an error less than 10% in predicting flow discharge for all 163 data.

A list of available codes of practice for self-cleansing sewers is presented and a review of appraisals of minimum velocity criterion is summarised. Comparisons of newly developed “minimum velocity” criteria and “minimum shear stress” criterion are presented. Some design charts are also given. These charts are applicable to non-cohesive sediments (typically storm sewers). It appears that sediment size and concentration need to be taken into account, and that a limited depth of sediment bed is recommended for large pipes (diameters > 1000 mm) to maximise their transport capacity.

A spillway with a trajectory bucket as an energy dissipator satisfies the requirements of both safety and economy. Many researchers have developed empirical formulae to predict scour location considering different hydraulic parameters and bucket configurations. An attempt has been made in this paper to estimate the location of maximum scour using parameters such as q, H 1, R, d 50 , d w and the lip angle of the bucket using an adaptive neuro fuzzy inference system (ANFIS). Extensive experimental results were collected and analysed in order to investigate the effect of different parameters on throw distance and scour location downstream of a trajectory bucket spillway. It was found that the scour parameter is a function of the fall Froude number, ratio of head to tailwater depth, ratio of radius of trajectory bucket to head, ratio of sediment mean size to head and lip angle of the bucket. The functional relationship is expressed in dimensionless form. This paper also presents an alternative to the regression in the form of neural fuzzy modelling. The results of this modelling were compared with the regression equation and it was found that the ANFIS results are highly satisfactory. The results of this study can be used to predict the location of maximum scour downstream of the trajectory bucket spillway.

No abstract

In this work, we report the effect of nanofillers and filler loading on mechanical, physical, dielectric, and thermal properties of the crosslinked polyethylene (XLPE) matrix. XLPE filled with 0.5-2% of zinc oxide (ZnO), aluminium oxide (Al 2 O 3 ), and organoclay (OMMT) nanofillers prepared by melt mixing with a single screw extruder followed by hot press moulding. Nanocomposites were tested as per ASTM standard methods and characterized with tensile test, water absorption, linear rate of burning, dielectric breakdown strength, and thermal stability. Scanning electron microscopy (SEM) was used to examine the surface morphology of the nanocomposites. The results showed that addition of nanofillers improved tensile strength, elongation at break, Young's modulus, burning rate, dielectric breakdown strength, and decomposition temperature. However, water absorption increased with time due to the hydrophilic properties of nanofillers. In general, based on the properties measured Al 2 O 3 exhibits the highest properties than those of ZnO and OMMT nanofillers. Addition of 1.5% of Al 2 O 3 in XLPE matrix has led to the improvement in tensile strength, elongation at break, Young's modulus, burning rate, and dielectric breakdown strength as compared to the unfilled polymer. J. VINYL ADDIT. TECHNOL., 25: E147-E154, 2019.

No abstract

No abstract

The electromagnetic field profile due to partial discharge is simulated. The x, y and z components of the electric and magnetic fields are calculated at the azimuthal plane of the single core xlpe cable, at the near field and far field regions inside and outside the cable. The results from the simulation give indication that the propagation mode of partial discharge signal at near field is hybrid transverse electric & transverse magnetic mode. The propagation mode at the far field region inside the power cable is transverse electric magnetic; and the propagation mode of the partial discharge outside the cable is quasi transverse electric magnetic.