Development of combined vector and torque control methods for independent two induction motor drives

Many applications use two or more motors operating in parallel configuration by using one variable speed drive. This system is able to control these multiple motors at the same desired motor speed operation which provide advantages in terms of components and cost reduction. However, the system is not able to control each motor separately if it is desired to operate at different speeds and it also cannot withstand the load disturbance. To address this problem, the design of combined Vector Control-Direct Torque Control (DTC) methods is proposed and their performance is investigated for the case of independent controlled two induction motors fed by single Five Leg Inverter (FLI) method. Double Zero Sequence (DZS) Injection Method Space Vector Pulse Width Modulation (SVPWM) scheme is used for the FLI. Simulation results from the Simulink/Matlab that verify the validity of the method are also included. The results show the ability of the proposed method to control motor speed independently under forward-reverse step speed command and load disturbance condition

The extraction of lignin from empty fruit bunch fiber via microwave-assisted acid hydrotrope solvent

Lignin is a sub-product from lignocellulose apart from cellulose and hemicellulose that produced from empty fruit bunch fiber (EFB). Lignin has low solubility and reactivity due to its bulky macromolecule structre. Being one of the wastes that being generated in massive amount, many alternatives has been taken to transform lignin into valuable products. To do so, many reactions are needed for the lignin to go through. In this study, lignin will be extracted from empty fruit bunch (EFB) with the aid of acid hydrotrope concentration of 30 % and microwave assisted with various extraction heating time and temperature. Characterization of lignin is done using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), Differential Scanning Calorimetry (DSC) and Nuclear magnetic resonance (NMR) while Scanning Electron Microscopy (SEM) and X-ray Powder Diffraction (XRD) used to characterize residues. The highest percentage of lignin yield and its purity obtained are 19.47 % and 96.63 % with the reaction time and temperature of the microwave is 30 minutes and 90 °C. From Fourier Transform Infrared Spectroscopy (FTIR), a wide band at 3430.09 cm-1 and 3413.45 cm-1 are observed due to O-H stretching vibration. As for peak at 1123.17 cm-1 and 1051.26 cm-1, it correspond to syringyl and guaicyl unit in both lignin and raw EFB. As for Thermogravimetric analysis (TGA), it shows that lignin decomposes slowly compared to raw EFB due to the aromatic structure of lignin that is very stable, therefore leading to difficulty of decomposing while from Differential Scanning Calorimetry (DSC), after removing cellulose and hemicellulose, glass transition temperature (Tg) obtained from lignin DSC spectroscopy is 193.05 °C at heat flow of 1.15 mW/mg. Next, from Nuclear magnetic resonance (NMR) spectroscopy, the signals observed around 6.5 – 8.0 ppm indicate aromatic H in syringyl and guaiacyl unit only at lignin spectra while at 3.3 – 4.0 ppm, raw EFB has an intense peak compared to lignin which attribute to methoxyl group. When the residue of the lignin as well as the raw EFB powder is characterized using X-ray Powder Diffraction (XRD), the crystallinity index of the lignin with reaction time and temperature of the microwave 30 minutes and 90 °C is the highest, 69.28 %. As a conclusion, an admissible percent of lignin yield and purity is able to be obtained with addition of acid hydrotrope depending on the variables. From the spectroscopies characterization, it is proved that lignin characteristics and properties are compatible for the production of new and value added products

Use of gas liquid chromatography in combination with pancreatic lipolysis and multivariate data analysis techniques for identification of lard contamination in some vegetable oils

A study was conducted to investigate the use of gas liquid chromatography (GLC) to identify lard (LD) contamination in palm oil (PO), palm kernel oil (PKO), and canola oil (CLO). Vegetable oils were deliberately adulterated with animal fats such as LD, beef tallow (BT), and chicken fat (CF) in varying proportions. In order to monitor the fatty acid (FA) compositional changes due to adulteration, GLC analyses of fatty acid methyl esters (FAME) were performed on 2-monoacylglycerol (2-MG) and neutral triacylglycerol (TAG) isolated from each sample. For the evaluation of FA data, multivariate statistical techniques were employed. The results showed that canonical discriminant (CANDISC) analysis was the most effective technique for discriminating LD-adulterated samples from those adulterated with other animal fats. Additionally, mathematical equations obtained by simple regression analysis could be used for quantification of LD contents in admixtures

The extraction of lignin from empty fruit bunch fiber via microwave-assisted deep-eutectic solvent heating

This work study about the extraction of lignin from Empty Fruit Bunch (EFB). It is a type of lignocellulosic waste produced during the palm oil extraction process. There are three main components of lignocellulosic, which is one of them is lignin. A deep eutectic solvent (DES) with microwave-assisted heating has been used as a process to extract the lignin from EFB and turn it into a value-product. This convenient method was started with the mixing of EFB and DES. After that, the mixture was heated via microwave synthesis reactor at different temperature and time parameters. The extracted lignin yield was dried and ground into a powder form. The highest lignin yield recovered is 30 % by the highest time and temperature. Interestingly, the purity of all lignin yields are above than 80 %. The highest yield of lignin was characterized. According to Fourier-Transform Infrared (FTIR) spectra, there was a significant functional group of phenolic and aliphatic hydroxyl in lignin. Besides, the methoxy group was also configured in lignin spectra. The presence of conjugated alkene also conveyed the characteristic of lignin. The FTIR spectra were intensified with 1H Nuclear Magnetic Resonance (NMR) spectra where there was a chemical shift in lignin and raw EFB which was designated to aliphatic and aromatic protons bonded to a carbon atom. Three regions of decomposition occur in the Thermogravimetric Analysis (TGA) spectra. The initial decompose temperature of lignin was lower compare to raw EFB. Next, second-stage lignin decomposed at 434.14 ℃ with weight loss of 36.21 %. Lastly, for the final stage, lignin decomposes at 552.54 ℃. Moreover, Differential Scanning Calorimetry (DSC) spectra demonstrate that the Tg value of lignin managed to be identified. However, the Tg value of raw EFB cannot be well defined. As for the characterization in residual fractions of EFB, the lowest crystallinity index (CrI) value of raw EFB has proven the presence of lignocellulosic in its structure. The residual fractions that reacted at higher temperatures have an inflated value of CrI as they contain abundant left out cellulose

Oblique impact analysis of cycling helmets made from kenaf (Hibiscus cannabinus) and flax (Linum usitatissimum) natural fiber

This paper describes the performance of a natural-fiber-based cycling helmet in an oblique impact with a simulated road surface. The linear accelerations and impact energy of a head form weighing 4 kg were measured and calculated. Helmet standards require helmets to be tested with a simple drop test onto an anvil. The maximum permitted deceleration of the dropped head form is typically 300g, which is equivalent to an impact velocity of 20 km/h (12.5 mph). The two helmets being tested were suspended onto a guided drop-table in the particular desired impact orientation. Just before impact, the test object was released from suspension so it can move unrestrained thereafter. The main advantage of this process is that the object is free to move naturally during impact, which provides for more realistic drop-testing. For oblique impact test, all helmets tested passed the requirement set by EN1078:2007 with linear acceleration measured lower than 250 g in a free fall test from 1.5 m platform. By comparing the resultant linear acceleration with a commercial cycling helmet, Kabuto Aero SL, flax aero helmet shows 11.82% reduction in the resultant linear acceleration with 214.16g. The Kenaf helmet recorded 168.48g, which corresponds to a 30.63% reduction in the resultant linear acceleration compared to the Kabuto helmet and 21.33% reduction compared to the Flax helmet

Chemical and functional properties of bovine and porcine skin gelatin

Abstract: The ability to compare bovine and porcine skin gelatin based on their amino acid composition, polypeptides pattern, bloom strength, turbidity and foaming properties were investigated. Amino acid composition of both gelatin showed that the content of glycine, proline and arginine in porcine gelatin were higher than bovine gelatin. However, the polypeptides pattern between both gelatin is closely similar. The bloom strength of porcine gelatin was higher than bovine gelatin from pH 3 to pH 10. Both gelatin possessed highest bloom strength at pH 9. The lowest bloom strength of bovine gelatin was at pH 3 while porcine gelatin at pH 5. The highest turbidity of bovine gelatin obtained at pH 7 while porcine gelatin at pH 9. Foam expansion and foam stability of bovine gelatin were higher than porcine gelatin at all concentrations

Aqueous enzymatic extraction of coconut oil

Aqueous extraction of coconut oil with various enzymes was investigated. Several enzyme preparations (cellulase, polygalacturonase, protease, and α-amylase) were used at different concentrations, pH, and temperature values to enhance oil extraction. After the oil had been released by the enzyme reaction, it was separated by centrifugation. The results showed that an enzyme mixture at 1% (w/w) each of cellulase, α-amylase, polygalacturonase, and protease at pH 7.0 and an extraction temperature of 60°C represented the most effective extraction conditions with an oil yield of 73.8%. Quality characteristics of the oil were as follows: moisture content, 0.11%; free fatty acid, 0.051%; peroxide value, 0.016 meq oxygen/kg; anisidine value, 0.026; iodine value, 8.3; saponification value, 260; and color, 0.6 (Y+5R). This technique for recovering oil from fresh coconut meat with enzymes is a significant improvement in both oil yield and quality over the traditional wet process

Определение достаточности пенсионного обеспечения в Малайзии на основе классификации групп по уровню дохода

The inadequacy of retirement wealth can significantly impact a country’s social support system. The increase of the size of the elderly population in line with the constant growth of life expectancy among Malaysians has triggered a question, are there enough resources to cover needs in retirement years? The main objective of this study is to estimate the retirement income adequacy of future retirees under a defined contribution (DC) plan, which is the Employee Provident Fund (EPF). The projection of retirement income adequacy uses cross-sectional data from the Malaysian Household Income Survey (HIS) 2014, based on 14,169 sample households. The households are categorized according to three different income groups, including Top 20% (T20), Middle 40% (M40) and Bottom 40% (B 40). In addition, this research also investigates the demographic and socio-economic determinants of retirement wealth adequacy using OLS and logistic regression. The result shows that 26% of households in the sample have inadequate retirement income, especially households in the B 40 group.Недостаточный уровень пенсионного обеспечения может значительно повлиять на систему социальной поддержки в государстве. Увеличение численности пожилого населения в соответствии с постоянным ростом продолжительности жизни среди малазийцев поставило вопрос о достаточности ресурсов для обеспечения потребностей людей в пенсионном возрасте. Основной целью данного исследования является определение адекватности размера пенсионных взносов в Фонд обеспечения работников (EPF) удовлетворению потребностей будущих пенсионеров. Для прогноза достаточности пенсионного обеспечения используются кросс-секционные данные из Малазийского исследования доходов домохозяйств (HIS) 2014 г., основанные на данных 14169 выборочных домохозяйств. Домохозяйства распределены по трем различным группам по уровню дохода, включая 20% самых обеспеченных (T20), 40% средних (M40) и 40% самых бедных (B 40). Кроме того, в данном исследовании также изучаются демографические и социально-экономические детерминанты достаточности пенсионного обеспечения с помощью метода наименьших квадратов (OLS) и логистической регрессии. Результат показывает, что 26% домохозяйств из исследуемой выборки имеют недостаточное пенсионное обеспечение, особенно это касается домохозяйств из группы B 40