Universiti Teknologi Malaysia

About: Universiti Teknologi Malaysia is a education organization based out in Johor Bahru, Malaysia. It is known for research contribution in the topics: Membrane & Control theory. The organization has 21644 authors who have published 39500 publications receiving 520635 citations.

Preparation and characterization of PVDF–PVP–TiO2 composite hollow fiber membranes for oily wastewater treatment using submerged membrane system

Abstract: A series of polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membranes made of different titanium dioxide (TiO2) concentrations with the presence of polyvinylpyrrolidone as additive was prepared. The membrane performances were characterized in terms of pure water flux, permeate flux, and oil rejection, while the membrane morphologies were analyzed using scanning electron microscope and atomic force microscope. The experimental results showed that when 2 wt.% TiO2 was incorporated into PVDF membranes, optimized permeate flux and oil rejection of 70.48 L/m2 h (±1.41) and 99.7% (±0.3), respectively, could be obtained when tested using 250 ppm synthesized oily solution under vacuum condition. Compared to the PVDF membrane without TiO2 addition, all the composite membranes showed relatively higher permeate flux and oil rejection. Based on the results obtained, it is reported that the composite PVDF membrane incorporated with 2 wt.% TiO2 exhibited the best separation performance in which comp...

An Improved Method to Predict the Position of Maximum Power Point During Partial Shading for PV Arrays

Abstract: For a photovoltaic (PV) system, it is widely assumed that the peaks of a partially shaded P–V curve are located at the multiples of $0.8{V_{{\text{oc}}}}$ , where ${V_{{\text{oc}}}}$ is the open-circuit voltage of the PV module. However, this assumption—known as the of $0.8{V_{{\text{oc}}}}$ model for partial shading—is not necessarily true. If the same model is used to design the maximum power point tracker (MPPT), it is very likely that the algorithm will scan the wrong region of the P–V curve and, hence, an incorrect global peak detection. This paper attempts to prove the inadequacy of the $0.8{V_{{\text{oc}}}}$ model when the number of modules in the string increases. Further, the work suggests a simple relationship to predict the correct position of the peaks. It is found that for a string of 20 modules ( ${V_{{\text{oc}}}}$ of 400 V), the maximum deviation between the actual and computed peak is less than 3 V, while for the $0.8{V_{{\text{oc}}}}$ model, the deviation reaches up to 50 V. In addition, using the proposed method, the MPPT efficiency can be improved by approximately 2%.

From Garbage to Biomaterials: An Overview on Egg Shell Based Hydroxyapatite

Abstract: The conversion of waste obtained from agricultural processes into biocompatible materials (biomaterials) used in medical surgery is a strategy that will add more value in waste utilization. This strategy has successfully turned the rather untransformed wastes into high value products. Eggshell is an agricultural waste largely considered as useless and is discarded mostly because it contributes to pollution. This waste has potential for producing hydroxyapatite, a major component found in bone and teeth. Hydroxyapatite is an excellent material used in bone repair and tissue regeneration. The use of eggshell to generate hydroxyapatite will reduce the pollution effect of the waste and the subsequent conversion of the waste into a highly valuable product. In this paper, we reviewed the utilization of this agricultural waste (eggshell) in producing hydroxyapatite. The process of transforming eggshell into hydroxyapatite and nanohydroxyapatite is an environmentally friendly process. Eggshell based hydroxyapatite and nanohydroxyapatite stand as good chance of reducing the cost of treatment in bone repair or replacement with little impact on the environment.

Hybrid Cascaded Multilevel Inverter (HCMLI) With Improved Symmetrical 4-Level Submodule

Abstract: This letter proposes an improved symmetrical 4-level submodule as a basic cell for generating multiple dc voltage levels. A hybrid cascaded multilevel inverter (HCMLI) topology is formed by the combination of n submodules and a full-bridge. A comparative analysis against the recent multilevel inverters reveals that the proposed topology requires less number of switches and dc sources. In addition, the proposed submodule reduces the number of conducting switch and gate driver requirements compared to the widely used half-bridge submodule. To validate the operation of the proposed HCMLI topology, experimental results of a 9-level single-phase inverter controlled by selective harmonic elimination pulse-width-modulation is presented.