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.

An overview of principal component analysis

Abstract: The principal component analysis (PCA) is a kind of algorithms in biometrics. It is a statistics technical and used orthogonal transformation to convert a set of observations of possibly correlated variables into a set of values of linearly uncorrelated variables. PCA also is a tool to reduce multidimensional data to lower dimensions while retaining most of the information. It covers standard deviation, covariance, and eigenvectors. This background knowledge is meant to make the PCA section very straightforward, but can be skipped if the concepts are already familiar.

A review of population-based meta-heuristic algorithm

Abstract: Exact optimization algorithms are not able to provide an appropriate solution in solving optimization problems with a high-dimensional search space. In these problems, the search space grows exponentially with the problem size therefore; exhaustive search is not practical. Also, classical approximate optimization methods like greedy-based algorithms make several assumptions to solve the problems. Sometimes, the validation of these assumptions is difficult in each problem. Hence, meta-heuristic algorithms which make few or no assumptions about a problem and can search very large spaces of candidate solutions have been extensively developed to solve optimization problems these days. Among these algorithms, population-based meta-heuristic algorithms are proper for global searches due to global exploration and local exploitation ability. In this paper, a survey on meta-heuristic algorithms is performed and several population-based meta-heuristics in continuous (real) and discrete (binary) search spaces are explained in details. This covers design, main algorithm, advantages and disadvantages of the algorithms.

Extracting hydroxyapatite and its precursors from natural resources

Abstract: Healing of segmental bone defects remain a difficult problem in orthopedic and trauma surgery. One reason for this difficulty is the limited availability of bone material to fill the defect and promote bone growth. Hydroxyapatite (HA) is a synthetic biomaterial, which is chemically similar to the mineral component of bones and hard tissues in mammals and, therefore, it can be used as a filler to replace damaged bone or as a coating on implants to promote bone in-growth into prosthetic implants when used in orthopedic, dental, and maxillofacial applications. HA is a stoichiometric material with a chemical composition of Ca10(PO4)6(OH)2, while a mineral component of bone is a non-stoichiometric HA with trace amounts of ions such as Na+, Zn2+, Mg2+, K+, Si2+, Ba2+, F−, CO32−, etc. This review looks at the progress being made to extract HA and its precursors containing trace amount of beneficial ions from biological resources like animal bones, eggshells, wood, algae, etc. Properties, such as particle size, morphology, stoichiometry, thermal stability, and the presence of trace ions are studied with respect to the starting material and recovery method used. This review also highlights the importance of extracting HA from natural resources and gives future directions to the researcher so that HA extracted from biological resources can be used clinically as a valuable biomaterial.

An overview of chemical enhanced oil recovery: recent advances and prospects

Abstract: Despite the progress made on renewable energy, oil and gas remains the world’s primary energy source. Meanwhile, large amounts of oil deposits remain unrecovered after application of traditional oil recovery methods. Chemical enhanced oil recovery (EOR) has been adjudged as an efficient oil recovery technique to recover bypassed oil and residual oil trapped in the reservoir. This EOR method relies on the injection of chemicals to boost oil recovery. In this overview, an up-to-date synopsis of chemical EOR with detailed explanation of the chemicals used, and the mechanism governing their oil recovery application have been discussed. Challenges encountered in the application of the various conventional chemical EOR methods were highlighted, and solutions to overcome the challenges were proffered. Besides, the recent trend of incorporating nanotechnology and their synergistic effects on conventional chemicals stability and efficiency for EOR were also explored and analysed. Finally, laboratory results and field projects were outlined. The review of experimental studies shows that pore-scale mechanisms of conventional chemical EOR is enhanced by incorporating nanotechnology, hence, resulted in higher efficiency. Moreover, the use of ionic liquid chemicals and novel alkaline–cosolvent–polymer technology shows good potentials. This overview presents an extensive information about chemical EOR applications for sustainable energy production.