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Search Results: 1 - 10 of 111 matches for " Azma Putra "
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A Combined Softening and Hardening Mechanism for Low Frequency Human Motion Energy Harvesting Application
Khalis Suhaimi,Roszaidi Ramlan,Azma Putra
Advances in Acoustics and Vibration , 2014, DOI: 10.1155/2014/217032
Abstract: This paper concerns the mechanism for harvesting energy from human body motion. The vibration signal from human body motion during walking and jogging was first measured using 3-axes vibration recorder placed at various places on the human body. The measured signal was then processed using Fourier series to investigate its frequency content. A mechanism was proposed to harvest the energy from the low frequency-low amplitude human motion. This mechanism consists of the combined nonlinear hardening and softening mechanism which was aimed at widening the bandwidth as well as amplifying the low human motion frequency. This was realized by using a translation-to-rotary mechanism which converts the translation motion of the human motion into the rotational motion. The nonlinearity in the system was realized by introducing a winding spring stiffness and the magnetic stiffness. Quasi-static and dynamic measurement were conducted to investigate the performance of the mechanism. The results show that, with the right degree of nonlinearity, the two modes can be combined together to produce a wide flat response. For the frequency amplification, the mechanism manages to increase the frequency by around 8 times in terms of rotational speed. 1. Introduction The significant reduction in power consumption to operate mobile gadgets and wireless sensors has induced vast research interest in harvesting energy from ambient sources. Scavenging energy from ambient vibration is one of the examples. Most vibration based scavenging device is traditionally configured as a linear resonant generator that consists of a single degree of freedom (SDOF) mass-spring-damper system. This particular generator is particularly useful for high frequency applications as well as when the ambient frequency does not vary with time. The optimum power of the linear resonant generator can only be obtained when the natural frequency of the device matches the excitation frequency. A Slight mismatch between these two frequencies may lead to a large reduction in the power harvested [1]. Researchers have introduced tuning techniques into the generator so that the natural frequency of the device can be changed according to the input frequency. Eichhorn et al. [2] used a prestress mechanism that can passively be adjusted by rotating a screw to alter the device natural frequency. An active tuning method proposed by Zhu et al. [3] utilized a microcontroller that can adjust the separation of interacting magnets to alter its natural frequency. However, active tuning may induce complex tuning scheme and
Effects of Structural Parameters on the Dynamics of a Beam Structure with a Beam-Type Vibration Absorber
Mothanna Y. Abd,Azma Putra,Nawal A. A. Jalil,Jamaludin Noorzaei
Advances in Acoustics and Vibration , 2012, DOI: 10.1155/2012/268964
Abstract: A beam-type absorber has been known as one of the dynamic vibration absorbers used to suppress excessive vibration of an engineering structure. This paper studies an absorbing beam which is attached through a visco-elastic layer on a primary beam structure. Solutions of the dynamic response are presented at the midspan of the primary and absorbing beams in simply supported edges subjected to a stationary harmonic load. The effect of structural parameters, namely, rigidity ratio, mass ratio, and damping of the layer and the structure as well as the layer stiffness on the response is investigated to reduce the vibration amplitude at the fundamental frequency of the original single primary beam. It is found that this can considerably reduce the amplitude at the corresponding troublesome frequency, but compromised situation should be noted by controlling the structural parameters. The model is also validated with measured data with reasonable agreement. 1. Introduction A beam-type absorber is one of the techniques to reduce undesirable vibration of many vibrating systems, such as a synchronous machine, mounting structure for a sensitive instrument, and other continuous structure in engineering. The absorber system usually consists of a beam attached to the host structure using an elastic element. The natural frequency of the absorber is then tuned to be the same as the troublesome operating frequency of the host structure to create counter force, which in return reduces the vibration of the structure. As beams are important structures in civil or mechanical engineering, several works have also been established to investigate the performance of the absorbing beam which is attached also to a beam structure. Among the earliest studies of the double-beam system is one proposed by Yamaguchi [1], which investigated the effectiveness of the dynamic vibration absorber consisting of double-cantilever visco-elastic beam connected by spring and viscous damper. The auxiliary beam is attached to the center of the main beam excited at its end by a sinusoidal force. It is found that the amplitude at resonances of the main beam is sensitive to the stiffness and mass of the absorbing beam. The damping ratio was formulated as a function of mass and layer stiffness of the absorber. Vu et al. [2] studied the distributed vibration absorber under stationary distributed force. A closed form was developed by utilizing change of variables and modal analysis to decouple and solve differential equations. Oniszczuk [3] studied the free vibrations of two identical parallel simply
Prediction of Waste Heat Energy Recovery Performance in a Naturally Aspirated Engine Using Artificial Neural Network
Safarudin Gazali Herawan,Abdul Hakim Rohhaizan,Azma Putra,Ahmad Faris Ismail
ISRN Mechanical Engineering , 2014, DOI: 10.1155/2014/240942
Abstract: The waste heat from exhaust gases represents a significant amount of thermal energy, which has conventionally been used for combined heating and power applications. This paper explores the performance of a naturally aspirated spark ignition engine equipped with waste heat recovery mechanism (WHRM). The experimental and simulation test results suggest that the concept is thermodynamically feasible and could significantly enhance the system performance depending on the load applied to the engine. The simulation method is created using an artificial neural network (ANN) which predicts the power produced from the WHRM. 1. Introduction The number of motor vehicles continues to grow globally and therefore increases reliance on the petroleum and increases the release of carbon dioxide into atmosphere which contributes to global warming. To overcome this trend, new vehicle technologies must be introduced to achieve better fuel economy without increasing harmful emissions. For internal combustion engine (ICE) in most typical gasoline fuelled vehicles, for a typical 2.0?L gasoline engine used in passenger cars, it was estimated that 21% of the fuel energy is wasted through the exhaust at the most common load and speed range [1]. The rest of the fuel energy is lost in the form of waste heat in the coolant, as well as friction and parasitic losses. Since the electric loads in a vehicle are increasing due to improvements of comfort, driving performance, and power transmission, it is therefore of interest to utilize the wasted energy by developing a heat recovery mechanism of exhaust gas from internal combustion engine. It has been identified in [2] that the temperature of the exhaust gas varies depending on the engine load and engine speed. The higher the engine speed the higher the temperature of the exhaust gas. Significant amounts of energy that would normally be lost via engine exhausts can thus be recovered into electrical energy. Theoretically, the energy from the exhaust gas can be harnessed to supply an extra power source for vehicles and will result in lower fuel consumption, greater efficiency, and also an overall reduction in greenhouse gas emission. The recovery and conversion of this heat into useful energy is a promising approach for achieving further reductions in fuel consumption and, as a result, reduction of exhaust emission. Among other technologies for waste heat recovery such as thermoelectric generators [3–5], secondary combustion for emission reduction [6], thermal storage system from heat exchanger [7], and pyroelectric using heat conduction
Carving Thumbnail/s and Embedded JPEG Files Using Image Pattern Matching  [PDF]
Nurul Azma Abdullah, Rosziati Ibrahim, Kamaruddin Malik Mohamad
Journal of Software Engineering and Applications (JSEA) , 2013, DOI: 10.4236/jsea.2013.63B014
Abstract: Images (typically JPEG) are used as evidence against cyber perpetrators. Typically the file is carved using standard patterns. Many concentrate on carving JPEG files and overlook the important of thumbnail in assisting forensic investigation. However, a new unique pattern is used to detect thumbnail/s and embedded JPEG file. This paper is to introduce a tool call PattrecCarv to recognize thumbnail/s or embedded JPEG files using unique hex patterns (UHP). A tool called PattrecCarv is developed to automatically carve thumbnail/s and embedded JPEG files using DFRWS 2006 and DFRWS 2007 datasets. The tool successfully recovers 11.5% more thumbnails and embedded JPEG files than PredClus.
The Effect of Defaunating Agents Supplementation and Time of Incubation on The In Vitro Dry Matter, Organic Matter Degradability and Products of Fermentation
S putra
Journal of Animal Production , 2006,
Abstract: In Vitro experiment was conducted to study the effect of defaunating agents supplementation and time of incubation on the dry matter, organic matter degradability and products of fermentation. A completely randomized design with split in time arrangement (4 x 5) on two replicates was used in this experiment. The first (main) factor was time of incubation (1.5, 3,0 and 4.5 hours respectively) and the second factor was no supplement of defaunating agent ( A, as a control), a supplement of 10% Hibiscus tilliaceus leaves (B), a supplement of 10% Hibiscus rosasinensis leaves (C), a supplement of 2% corn oil (D), and a supplement of 2% coconut oil (E). Results of the experiment indicated that treatment C increased 10.66% DM degradability which were significantly different (P<0.03) than treatment A, while DM degradability on treatment B, D, and E were increased 4.29, 5.58, 6.24% than treatment A, respectively but it were not significantly different. Defaunating agents supplementation (treatment B, C, D, and E) increased 8.59, 15.19, 9.62, and 8.01% OM degradability, respectively (P<0.03) than without supplementation (A), but between defaunating agents supplementation were not significantly different. DM degradability during incubation (1.5 to 4.5 hours) were significant different statistically (P<0.04) which the highest was on 4.5 hour incubation, while OM degradablity during incubation were not significantly different. Total VFA on the defaunating agents supplementation and during time of incubation were significantly different which the highest were on the Hibiscus rosasinensis supplementation (C) and on the 4.5 hours incubation, respectively. N-ammonia on the defaunating agents supplementation and during incubation were not significantly different (P>0.05) which the highest were on the Hibiscus rosasinensis supplementation (C) and on the 3.0 hours incubation, respectively. It was concluded that defaunating agents were affected significantly different on the DM and OM degradability and total VFA, but were not affected on the N-ammonia. Time of incubation from 1.5 to 4.5 hours increased DM, OM degradability and total VFA, but N-ammonia was decreased. Hibiscus rosasinensis was the best defaunating agents, particularly it was increased DM, OM degradability, total VFA and N-ammonia, absolutely. (Animal Production 8(2): 121-130 (2006) Key Words: Defaunating agents, Time of incubation, DM and OM Degradability, Products of fermentation
The Relationship between Mouth Squamous Cell Carcinoma (MSCC) with HPV Infection and the Presence of p53 & c-myc Mutation  [PDF]
Adi Prayitno, Elyana Asnar, Suhartono Taat Putra
Journal of Cancer Therapy (JCT) , 2013, DOI: 10.4236/jct.2013.45105
Abstract:


Introduction: Now the molecular epidemiology is a new experience. It’s was noted that ninety percent of mouth cancers are squamous cell carcinomas and recorded 0.96% year of all cancers in Indonesia. Human papilloma virus (HPV) was implicated in pathogenesis of cancer. As a remark, that mutations of p53 and c-myc are found 50% in cancer. Objective: Aims of this research were to know the relationship between the mouth squamous cell carcinoma (MSCC) with HPV infection, the presence of p53, and c-myc genes mutation. Methods and Material: Tissue biopsy frozen sections from Benign Mouth Squamous Cell (BMSC) and MSCC patients were collected from Mouth and Dental Department of Muwardi District Hospital in Solo—Indonesia. To amplify L1-HPV gene for fixed the HPV etiology, amplified p53 and c-myc genes continued with SSCP analysis and followed with measurement using densitometer to see mutation existence. The collected data were analyzed with Chi Square Test. Results: None of the sample of patients with BMSC with positive HPV showed p53 gene mutation or c-myc gene. From eleven samples obtained from patients with MSCC who were positive HPV showed 18.2% had mutations in the p53 gene and 9.1% had mutations in c-myc gene. The chisquare test was shown to have significant differences between the MSCC with HPV infection and the presence of p53 and c-myc genes mutation. Conclusion: HPV is a risk ingredient for MSCC.


Theoretical Modeling for Predicting the Optimum Twist Angle of Cotton Fiber Movement on OE Yarn Made by Rotor Spinning Machine  [PDF]
Valentinus Galih Vidia Putra, M. Farchani Rosyid
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.35074
Abstract: This paper presents theoretical modeling for predicting the optimum twist angle on yarn made by open end rotor spinning machine in textile industry. Fiber movement on yarn can be used for predicting the optimum twist angle which can be used to reduce yarn breaking in spinning process. In this research the twist angle has been found and the result of this research shows the twist angle around 45°; and the theoretical result of the ratio of rotor diameter to fiber length is \"\".
AKTIVITAS ANTIBAKTERI EKSTRAK KULIT BUAH MANGGIS (Garcinia mangostana L.) SERTA KANDUNGAN SENYAWA AKTIFNYA [Antibacterial Activity of Mangosteen (Garcinia mangostana L.) Husk Extract, and its Active Compounds]
I Nengah Kencana Putra
Jurnal Teknologi dan Industri Pangan , 2010,
Abstract: Mangosteen husk is traditionally has been used by palm sugar farmers for preserving palm sap. This research was aimed to determine the antibacterial activity of mangosteen husk extract against Leuconostoc mesenteroides and Lactobacillus plantarum (which are the most common palm sap-spoiling bacteria), and to analyze the active compounds of the extract. Methanol extract of mangosteen husk showed antibacterial activity against both L. mesenteroides and L. plantarum with inhibition zone diameter of 12.70 and 11.02 mm respectively. Observation on the fractions of the extract showed that chloroform and ethyl acetate fractions exhibited antibacterial activity on the above bacteria . Identification of the active compounds performed by GC-MS showed that the dominant compound in the chloroform extract was 9, 10-anthracenedione, while that in the ethyl acetate extract was 7H-furo 3’,2’:4,5 furo 2,3-c xanthen-7-one. Those compounds belonged to the derivate of anthraquinone and xanthone respectively.
CEMARAN PESTISIDA KLOR-ORGANIK PADA SEDIMEN DANAU BUYAN BULELENG BALI
Ida Bagus Putra Manuaba
Bumi Lestari , 2012,
Abstract: This is an expost facto study with Analytical Cross Sectional Study design, within two step activities, i.e. field study in order to gain sampling zone and obtaining sample needed. Followed by laboratory works in order to obtain pesticide residual contamination on water. Sample preparation for this purposed was carried out following a standard method. Gas chromatography was employed in order to gain the pesticide contaminant. Positive organochlorine pesticide contaminant, i.e. DDT and chlorotalonile were observed from 55 sampling point of sediment taken from 5 sampling zone. DDT in the sediment is 13.6 ppb with still bellow the maximum level of 42 ppb. Chlorotalonile in sediment is 12.3 ppb. There is no threshold value of chlorotalonile, however, this contamination still bellow the RfD 15 ppb and ADI 30 ppb (PIP, 1995; Caroline, 1997).
BIOAKUMULASI RESIDU CEMARAN DDT DAN KLOROTALONIL PADA IKAN KARPER DAN NILA DANAU BUYAN BULELENG BALI
Ida Bagus Putra Manuaba
Bumi Lestari , 2009,
Abstract: Analysis of DDT and chlorotalonil bioaccumulation on carp and nile fish tissues at Buyan Lake were performed. The study involve two step activities, i.e. field study for gaining sampling zone and sample needed, followed by laboratory works for obtaining DDT and chlorotalonil residual bioaccumulation on fish. Sample preparation for this purposed was carried out following a standard method. Gas chromatography was employed for determining accumulation of DDT and chlorotalonil. Average bioaccumulation of DDT on carp and nile is 16.6 and 9.6 ppb, respectively, while, average chlorothalonil bioaccumulation on the same fishes is 11.9 and 13.3 ppb, respectively.
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