Modeling And Simulation Of Wind Turbine For Partial Load Operation

The purpose of this research is mainly to model a wind turbine with doubly fed induction generator (DFIG) and to investigate its behavior in partial load operation using computer simulation. System behavior analysis and simulation are two particular approaches applied in this research. The wind turbine model is developed whereby the behavior of its main components is described by mathematical model and transformed in simulation model in MATLAB/Simulink. The simulation model is carried out in partial load operation at a wind speed of 9 m/s. The physical quantities including generator speed, torque and electrical power output are measured and evaluated. By using variable speed generator, a wind turbine model with optimum power generation at wind speed between 4 m/s to 13 m/s is created. This research shows that if mathematical models represent the wind turbine accurately, then the proposed model can be used to observe the dynamic behavior of wind turbine precisely, efficiently and inexpensively. The simulation result is expected to be a reference for extending the knowledge of dynamic behavior of wind turbines and optimize the performance of future large-scale wind turbine systems

Directional felling within selective management system of Peninsular Malaysia: comparison between current and extended techniques

Directional felling has been implemented in Peninsular Malaysia as part of the Selective Management System (SMS) to obtain optimum yield from the forest resources while reducing damage to the environment and residual trees. Some questions regarding its effectiveness have been questioned a few times, resulting in a joint research project at Ulu Jelai Forest Reserve, Pahang, Malaysia to compare between the current directional felling technique and the new (extended) techniques, in terms of accuracy of tree felling, volume of felling logs, expected damage on residual trees, and time taken for tree felling. For this study, 38 trees were felled with the current and extended techniques. By using the extended technique, 91.3% of the trees were felled within the 0°-5° range, and 100% within the 0°-10° range, compared to 28.01% (within the 0°-5° range) using the current technique. The extended technique also recorded higher volume recovery (14% higher) and lower damage on the residual trees by almost 50%. However, the extended technique took longer time, i.e. 4.56 minutes per tree, as compared to 2.50 minutes. The main contributor to the difference is the presence of gauge cut in the extended technique. Generally, the studies suggest that the extended technique is preferred as it is safer to the feller and surrounding people, while reducing the collateral damage on the harvested trees, as well as the residual trees

Molecular Docking of Known Carcinogen 4- (Methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) with Cyclin Dependent Kinases towards Its Potential Role in Cell Cycle Perturbation

Cell cycle is maintained almost all the times and is controlled by various regulatory proteins and their complexes (Cdk+Cyclin) in different phases of interphase (G1, S and G2) and mitosis of cell cycle. A number of mechanisms have been proposed for the initiation and progression of carcinogenesis by abruption in cell cycle process. One of the important features of cancer/carcinogenesis is functional loss of these cell cycle regulatory proteins particularly in CDKs and cyclins. We hypothesize that there is a direct involvement of these cell cycle regulatory proteins not only at the genetic level but also proteins level, during the initiation of carcinogenesis. Therefore, it becomes significant to determine inconsistency in the functioning of regulatory proteins due to interaction with carcinogen 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Hence, we investigated the interaction efficiency of NNK, against cell cycle regulatory proteins. We found a different value of ΔG (free energy of binding) among the studied proteins ranging between -3.29 to -7.25 kcal/mol was observed. To validate the results, we considered Human Oxy-Hemoglobin at 1.25 Å Resolution, [PDB_ID:1HHO] as a +ve control, (binding energy -6.06 kcal/mol). Finally, the CDK8 (PDB_ID:3RGF) and CDK2 (PDB_ID:3DDP) regulatory proteins showing significantly strong molecular interaction with NNK -7.25 kcal/mol, -6.19 kcal/mol respectively were analyzed in details. In this study we predicted that CDK8 protein fails to form functional complex with its complementary partner cyclin C in presence of NNK. Consequently, inconsistency of functioning in regulatory proteins might lead to the abruption in cell cycle progression; contribute to the loss of cell cycle control and subsequently increasing the possibility of carcinogenesis

Guidelines for process safety hazard assessment based on process information

In any new chemical process development and design, process safety is a critical aspect to be considered besides economic and technical feasibility of the manufacture of the product. A lack of proper hazard assessment during the design phase may later result in accidents with disastrous consequences to workers, the public as well as the environment. Many methods have been introduced to qualitatively and quantitatively assess the safety level of processes. Despite the availability of a large amount of methods, a systematic framework that details guidelines for hazard identification, risk assessment, safety measure design, and safe critical decision-making is still missing. To address this issue, the main objective of this study was to propose a systematic framework that outlines comprehensive guidelines for assessing the safety performance of processes based on information from the piping and instrumentation diagram (P&ID). Apart from proposing the framework, appropriate strategies for minimizing safety hazards and risks are also recommended. In addition, the user is assisted in selecting the most appropriate assessment method according to his or her needs and the scope and constraints of the assessment. A case study is presented to illustrate the application of the proposed framework

The validation of project management reference framework using rasch model

A project management reference framework has been developed to deal with the scarcity of a commonly recognized term of reference for Malaysian public project management. The development of this framework was instigated by the lack of terms of reference for the practice to generate the key competencies that public project managers should acquire. In this study, a working framework has been validated using the RASCH measurement model to see whether the construct identified is fit to be included within the framework. A Questionnaire survey has been used for data collection. The sample chosen was from G7 construction companies registered with CIDB and government organizations involved with construction projects. Data has been analyzed using dimensionality test and item fit testing. Through the analysis, the construct, which consists of twenty-four significant activities, has been identified to be included in the five major phases of the project lifecycle, namely the inception stage, design stage, tendering stage, construction stage, and closeout stage. With this analysis, a working Project Management Reference Framework has been validated and hopefully beneficial to the industry’s practitioner

The cytotoxic effect and glucose uptake modulation of Baeckea frutescens on breast cancer cells

Background: Baeckea frutescens (B. frutescens) of the family Myrtaceae is a plant that has been used in traditionalmedicine. It is known to have antibacterial, antipyretic and cytoprotective properties. The objective of this study isto explore the mechanism of B. frutescens leaves extracts in eliminating breast cancer cells. Method: B. frutescens leaves extracts were prepared using Soxhlet apparatus with solvents of different polarity. The selective cytotoxicity of these extracts at various concentrations (20 to 160 μg/ml) were tested using cell viability assay after 24, 48 and 72 h of treatment. The IC50 value in human breast cancer (MCF-7 and MDA-MB-231) and mammary breast (MCF10A) cell lines were determined. Apoptotic study using AO/PI double staining was performed using fluorescent microscope. The glucose uptake was measured using 2-NBDG, a fluorescent glucose analogue. The phytochemical screening was performed for alkaloids, flavonoids, tannins, triterpenoids, and phenols. Results: B. frutescens leaves extracts showed IC50 value ranging from 10 -127μg/ml in MCF-7 cells after 72 h of treatment. Hexane extract had the lowest IC50 value (10μg/ml), indicating its potent selective cytotoxic activity. Morphology of MCF-7 cells after treatment with B. frutescens extracts exhibited evidence of apoptosis that included membrane blebbing and chromatin condensation. In the glucose uptake assay, B. frutescens extracts suppressed glucose uptake in cancer cells as early as 24 h upon treatment. The inhibition was significantly lower compared to the positive control WZB117 at their respective IC50 value after 72 h incubation. It was also shown that the glucose inhibition is selective towards cancer cells compared to normal cells. The phytochemical analysis of the extract using hexane as the solvent in particular gave similar quantities of tannin, triterpenoids, flavonoid and phenols. Presumably, these metabolites have a synergistic effect in the in vitro testing, producing the potent IC50 value and subsequently cell death. Conclusion: This study reports the potent selective cytotoxic effect of B. frutescens leaves hexane extract against MCF-7 cancer cells. B. frutescens extracts selectively suppressed cancer cells glucose uptake and subsequently induced cancer cell death. These findings suggest a new role of B. frutescens in cancer cell metabolis

Eigenfrequency shift of piezoelectric backplate in vibro-acoustic energy harvesting

Noise is increasingly recognised as a serious, worldwide public health concern. Noise is a type of occupational hazard that can cause damage to hearing and other health effects in workers who are exposed to high levels of noise in their work environment. Traditionally, noise can be controlled and suppressed but recently, noise can be useful and converted into electrical energy. The process of converting noise or acoustic waves into electrical energy by using a quarter wavelength resonator tube embedded with a flexible piezoelectric backplate was used in this study. The results show the maximum output voltage of 1.41 V/Pa at 112 Hz and 0.44 V/Pa at 225 Hz in the experiment, and 1.44 V/Pa at 106 Hz and 0.41 V/Pa at 226.5 Hz with incident sound waves at 90 dB. A parametric study was then performed by adjusting the lumped pointed mass at the piezoelectric backplate to tune the resonant frequencies of the system and the optimal power output. The point mass has given significant change in the acoustic properties. The maximum output power increased from 20.4 at 112 Hz using a flexible back plate to 711 at 119.75 Hz. Various small power applications can benefit from the approach by reducing and absorbing specific low-frequency bandwidths of continuous noise in the environment

Guidelines for Process Safety Hazard Assessment Based on Process Information

In any new chemical process development and design, process safety is a critical aspect to be considered besides economic and technical feasibility of the manufacture of the product. A lack of proper hazard assessment during the design phase may later result in accidents with disastrous consequences to workers, the public as well as the environment. Many methods have been introduced to qualitatively and quantitatively assess the safety level of processes. Despite the availability of a large amount of methods, a systematic framework that details guidelines for hazard identification, risk assessment, safety measure design, and safe critical decision-making is still missing. To address this issue, the main objective of this study was to propose a systematic framework that outlines comprehensive guidelines for assessing the safety performance of processes based on information from the piping and instrumentation diagram (P&ID). Apart from proposing the framework, appropriate strategies for minimizing safety hazards and risks are also recommended. In addition, the user is assisted in selecting the most appropriate assessment method according to his or her needs and the scope and constraints of the assessment. A case study is presented to illustrate the application of the proposed framework

Inflammation in embryology: A review of neuroinflammation in spina bifida

The occurrence of neuroinflammation after the failure of neural tube closure, resulting in spina bifida aperta, is well established but whether or not neuroinflammation contributes to damage to the neuroepithelium prior to and during closure is not known. Neuroinflammation may occur at different time periods after perturbation to the developing spinal cord. Evidence suggests that early neuroinflammation is detrimental, whereas the later chronic phase of neuroinflammation may have useful roles. The role of neuroinflammation in neural tube defects is complex. It is important to make the distinction of whether neuroinflammation is important for neuroprotection or detrimental to the neural tissue. This may directly be influenced by the location, magnitude and duration of the insult, as well as the expression of neurotrophic or neurotoxic molecules. The current understanding remains that the chronic damage to the developing spinal cord is likely due to the chemical and mechanical damage of the exposed neural tissue owing to the aggressive intrauterine environment, described as the “two-hit mechanism”. Astrogliosis in the exposed spinal cord has been described in animal models of spina bifida after the failure of closure during embryonic life. Still, its association with neuroinflammatory processes is poorly understood. In this review, we will discuss the current understanding of neuroinflammation in neural tube defects, specifically spina bifida, and highlight inflammation-targeted strategies that may potentially be used to treat this pathophysiological condition