Search

The application of wavelet transforms (WT) and Hilbert transform (HT) for identification of an elastically support cylinders due to free vibration will be explained in this paper. The influence of the elastic limit will cause the spring to be distributed linearly. The interesting thing about this paper is that by attaching the wire to the elastically support cylinder, it will cause the spring to be distributed linearly or nonlinearly. To identify the system, wavelet transform and Hilbert transform applications are used. The envelope of the time response and instantaneous frequency are extracted using the Wavelet and Hilbert transform to identify the nonlinear characteristics of the system. Responses in the range of the lock-in and nonlinear jump phenomena are investigated clearly. Finally, the linear and nonlinear spring properties of the system are identified using the wavelet and Hilbert transform. [ABSTRACT FROM AUTHOR]

This paper discusses the effect of dimpling on an elastic cylinder using computational fluid dynamics (CFD) simulation. The simulation CFD approach is used because it is low-cost. The purpose of this study is to model a cylinder that has three different cylinder surface configurations: smooth cylinder, outwardly dimpled, and inwardly dimpled on half the surface of the cylinder (front). This aims to increase the coefficient lift value of the cylinder and decrease the coefficient drag value in order to utilize it as alternative energy in the cylinder system supported by two beams. Furthermore, the numerical simulation is performed on an elastic cylinder with a velocity of 3.5 m/s and an aspect ratio (L/D) of 5.6. The time-domain responses of force coefficients and structural displacements are converted into frequency-domain responses using the Fast Fourier Transform to characterize the structure responses. The results demonstrate that the cylinder surface is very successful at improving the lift coefficient and decreasing the drag coefficient while maintaining the velocity constant. The time necessary to commence cylinder displacement varies depending on the circumstance. For an inwardly dimpled cylinder, the displacement initiation start time is 0.1 s; for a smooth and outwardly dimpled cylinder, the displacement initiation start time is 0.25 s. The highest vortex shedding frequency lift coefficient is obtained from an inwardly dimpled cylinder, followed by an outwardly dimpled cylinder, while the lowest is a smooth cylinder. While the frequency obtained due to changes in surface variation does not change significantly, which is around 15 Hz. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effect and percentage on eating behavior patterns (feeding frequency, duration of eating, frequency of rumination, duration of rumination, and consumption) of Brahman cross in KPT Maju Sejahtera, Tanjung Sari District, South Lampung Regency. This research was conducted in October-November 2021. At KPT Maju Sejahtera, Wawasan Village, Tanjung Sari District, South Lampung Regency. The experimental design used was a Randomized Block Design (RAK) with 3 treatments with 3 replications. The treatments given were control (basal feed with the addition of corn cobs without ammonia) (P0), basal feed with the addition of 2.5% ammonium corncobs (P1), basal feed with the addition of 5% ammonium corncobs (P2). The data obtained were tabulated simply and then analyzed descriptively. The results showed that the addition of ammoniated corn cobs with different urea levels had no effect on the eating behavior of Brahman cross. [ABSTRACT FROM AUTHOR]

This study aims to determine the effect of ignition timing on exhaust emissions and engine characteristics (torque, power, and fuel consumption) using Ethanol (E100) fuel. This type of research is an experimental study with the object of the Yamaha Vega Force FI 115 cc engine using a compression ratio of 11:1 and the addition of injection duration of 24 percent from standard conditions with ignition timings of 3 degrees, 5 degrees, 8 degrees, 11 degrees and 13 degrees before TDC. Tests were carried out using a dynamometer, measuring cup, and gas analyzer. The best research results were obtained at an ignition time of 11 degrees before TDC. The percentage increase in power at the ignition timing of 11 degrees before TDC is an average of 3.31 percent, and the torque increase is 3.98 percent. An ignition timing of 11 degrees before TDC also improves specific fuel consumption by an average of 9 percent. In addition, the ignition timing of 11 degrees before TDC also reduces HC levels by 16 percent and decreases CO levels by 12 percent. [ABSTRACT FROM AUTHOR]

This study aims to know the effect of resin and hardener ratio of epoxy matrix on the manufacture of carbon fiber composite materials using the VARTM printing method on the mechanical properties of carbon fiber composites and to know the best formulation between resin and hardener used in the VARTM printing methods. This research is an experimental study, with the subject being a carbon fiber composite test sample made using the composition of resin and hardener epoxy matrix ratios that were varied and printed using the VARTM method. The resin and hardener ratios of an epoxy matrix are 60%:40%, 70%:30%, and 80%:20%. Processing and analysis of test data using descriptive statistical methods. The results of this study indicate carbon fiber composites printed by the VARTM method, the 70%:30% ratio, in higher tensile and flexural strengths of 10.8% and 35. 7% respectively, compared to the ratio of 60%:40%, while the 80%:20% resin and hardener ratio, a decrease in tensile and flexural strength respectively by 21% and 45.3% when compared to the 60%:40 % ratio. In addition, the 60%:40% ratio is the lowest density compared to 70%:30% and 80%:20% ratios. Next, the best formulation of resin and hardener ratio to increase the strength of carbon fiber composites printing using the VARTM method is 70%:30%. In contrast, for the density value, the best formulation is 60%:40%. [ABSTRACT FROM AUTHOR]

Malaria is an infectious disease caused by a parasite known as Plasmodium, which infects red blood cells. Malaria detection can be done by using a Blood Smear examination through a microscope. The patient's blood sample will be stained with fluorescence and then viewed using a microscope to see the presence of Plasmodium parasites in the blood. Computer vision and deep learning method can also be used to detect malaria from red blood cell images. Previous studies showed convolution neural network (CNN) model can accurately detect malaria from red blood cell images. However, the CNN architecture and parameters played an important role in increasing accuracy. This study investigated the effect of hyperparameter tuning toward accuracy, precision, recall, f1-score and Matthew Correlation Coefficient (MCC). Two architectures, Rajaraman and BaselineNet were used for the experiment and grid searching technique to find the best hyperparameter used in this research. The best hyperparameter for Rajaraman architecture were 30 epochs, ADAMAX optimizer, 32 batch-size, and 0.01 learning rate with 96.7% accuracy. The best hyperparameter for BaselineNet architecture were 20 epochs, SGD optimizer, 0.1 learning rate and 32 batch size. Overall, the hyperparameter tuning can increase 1.93% for Rajaraman architecture and 0.36% for BaselineNet architecture compared to non-tuning hyperparameter. [ABSTRACT FROM AUTHOR]

Crime is a complicated problem that broadly impacts all levels of society. This study tries to develop an information system to display and map the number of crimes in Batu Bara Regency in Grouping. The method used is K-Means Clustering, where grouping is done to determine the level of vulnerability of an area. The grouping is taken based on the density of the crime scene from the crime that occurred so that the resulting output is expected to make it easier for users to distinguish the level of vulnerability between one area and another based on the grouping done. The results of this study indicate that security in Batu Bara Regency tends to be vulnerable around the city center. In contrast, suburban areas with relatively low population density tend to be safer. In terms of time, the crime with the highest identity occurred late at night. [ABSTRACT FROM AUTHOR]

Currently, used tire rubber was widely used as a material replacement for coarse or fine aggregate in concrete, asphalt, and soil. The previous studies showed that the addition of rubber tire crumbs (RTC) in concrete could reduce the compressive strength and modulus of elasticity of concrete. This study observes the effect of RTC in the concrete mixture, on their flexural properties. The specimen is a concrete beam with a length of 60 cm and has a square cross-section of 15 cm x 15 cm. RTC is added as a partial substitute for sand, with the RTC contents of 0%, 5%, 10%, 15%, and 20% to the weight of sand. There are 2 variations of concrete mix design, which are 35 MPa and 17 MPa of concrete strength (fc'). The flexural strength test of the concrete beam was carried out on 10 specimens at 28 days old. The research found that the higher of RTC contents, the smaller the flexural strength of the concrete. The decrease in flexural strength is also influenced by concrete strength. The higher strength concrete will experience a smaller decrease in flexural strength caused by the increase of RTC contents. The concrete flexural strength decreased by an average of 56% on the 17 MPa, but 28% on the 35 MPa concrete strength (fc'). The results of this study can be used as a consideration in the application of the RTC concrete as a beam that withstands flexural loads. [ABSTRACT FROM AUTHOR]

Indonesia is a country that is flanked by three tectonic plates, called the Indo-Australian Plate, the Eurasian Plate, and the Pacific plate. The three tectonic plates are still active today, increasing the risk of the potential for tectonic earthquakes to occur in Indonesia. On May 27, 2006, the city of Yogyakarta experienced a natural disaster, a tectonic earthquake which was quite strong at the 6.3 Richter Scale according to USGR calculations (United States Geological Survey). This earthquake caused a lot of losses, one of which many buildings collapsed or were damaged, making these buildings uninhabitable. According to BNPB data for 2020 (National Disaster Management Agency), more than 1000 units of worship facilities and offices were damaged, and as many as 376 units of health facilities also had structural damage. For this reason, research was taken on earthquake forces on building structures using the response spectrum method based on SNI 1726:2019, which BSN only released in the last few years. Response Spectrum is a method that analyzes earthquake forces based on the structure's curve between periods and acceleration according to the earthquake map in Indonesia. This method analyzed the structural response in the 16-floor Student Dormitory UMY using ETABS software. It was concluded in this study that the story drift exceeds the permitted limit for floors 1 to 10 in the X-direction and the Y-direction for the 1st and 4th floors to the rooftop. There is no P-Delta effect in either the X or Y directions. The horizontal structural irregularity analysis has a re-entrant corner irregularity (type 2). For the analysis of vertical irregularities, there were soft-story irregularities type 1a and 1b and vertical geometric irregularities (vertical irregularity type 3). [ABSTRACT FROM AUTHOR]

This study aims to examine the improvement of mathematical representation abilities in integral calculus. The research method used was a quasi-experimental design with a pretest-posttest nonequivalent multiple group design. The population is students of the Mathematics Education Study Program at University in West Java, Indonesia. Class 1A and 1B were the samples in this study. The technique of taking the research subject uses purposive sampling. The instrument in this study consisted of a mathematical representation ability test. The test in this study used a pretest and posttest students' mathematical representation ability, and the Group Embedded Figure Test (GEFT). The data analysis technique used kruskall wallis test and mann whitney test. The results showed there is an interaction effect of learning model (Geogebra-assisted project-based learning model/project-based learning model) and cognitive style (Field-independent (FI) and Field-dependent (FD) towards improving students' mathematical representation ability. The improvement of students' mathematical representation ability using the Geogebra-assisted project-based learning model which has a field-dependent cognitive style is better than students using the project-based learning model which has field-independent and field-dependent cognitive styles. [ABSTRACT FROM AUTHOR]

The problems of ergonomic workload can occur in physical and mental aspects. Likewise in PT Korma Jaya Utama especially in the Extraction department, some problems are indicated with physical and mental aspects. The operator must lift manually 150 kg/barrel with a distance of 15 m, and it must be done repetitively during work hours. This research aims to assess the physical and mental workload of operators and design the ergonomic material handling to minimize the problems. The method in asses physical workload is using energy consumption calculation, and the mental workload is using the NASA-TLX method. According to the calculation, the result of energy consumption and NASA-TLX assessment are categorized as very heavy. It means that the job is has a high risk for physical, mental, and frustration indicators. The score of MD is 350, PD is 375, and F is 330. The mental and physical workload was classified as very high and required to be improved. According to the previous research, the physical workload is increased by the elevation of mental workload. Thus, human factors and ergonomic tools can minimize the mental, fatigue, and stress of operator. [ABSTRACT FROM AUTHOR]

As a new form of manufacturing industry, social manufacturing shows the complexity of social-cyber, such that the source of manufacturing services is social. It thus can exacerbate uncertainty and dynamic supply of services. The Cyber-Physical System (CPS) merging with social media produces a social manufacturing and basic theory for future production organization. Three aspects that are the core of social manufacturing are configuration, operation, and management perspectives, which are expected to contribute to the transformation of production modes and social innovation. Social manufacturing is proposed as an innovative manufacturing solution for the future era of product personalization customization. This study aims to develop a conceptual model of an integrated production system based on the internet of things in social manufacturing. The methods used include literature studies, interviews, model design, testing of production system models in the laboratory scope, and analysis of the results of testing production system models. The output of this research is a conceptual model of an integrated production system based on the internet of things in social manufacturing. [ABSTRACT FROM AUTHOR]

Sand mining using heavy equipment causes groundwater pollution in Kranggan Village, Kulon Progo. This study aimed to develop a monitoring system for measuring water quality to determine the level of groundwater pollution in that location. This Android-based well water quality monitoring system was built using the C programming language, namely Arduino IDE. Data collection methods used in the development of this system are literature study, observation, and interviews. The application development phase includes analysis, system design, implementation, and testing. This program is implemented using various sensors, pH sensors, temperature sensors, and TDS sensors, each used to measure the pH value, temperature, and the number of dissolved solids. This system is also equipped with a wifi module used to send data from the device to the application created. The process that regulates the input and output of this system uses the Arduino nano and Arduino nano shield. As the primary power source used in this system is a fixed voltage adapter. An Android-based water quality monitoring system that could display measurement results and readings. The test results show that the tools and applications could run well. There are only a few shortcomings in the appearance of the application that is less attractive. [ABSTRACT FROM AUTHOR]

The Covid 19 pandemic that began in Indonesia since March 2020 has had an impact in various fields, one of which is in the field of education. The education system, which initially took place face-to-face, has switched to online learning. Online learning has shortcomings, one of which is that the material is difficult for students to understand because it cannot meet face to face directly. This study aims to measure the quality of online learning using the Kano method based on student perceptions. The Kano method is a method that aims to categorize the attributes of a product or service, how well the product or service is able to satisfy consumer needs. The results of processing using the Kano method show 8 attributes which are categorized as must-be, 1 attribute is indifferent category, 1 attribute is one-dimensional category, and 7 attributes are attractive category. The category that needs to be improved first is the must-be, namely attributes are 1 (Use of interactive tools for online learning), 2 (Ease of access and connection of online learning platforms), 3 (Selection of varied online learning platforms), 4 (The consistency of lecturers in delivering lectures is good), 6 (Lecturers are reliable in using online learning platforms), 7 (Lecturers respond quickly and efficiently to student needs while studying online), 8 (Lecturers are able to adapt from conventional learning to online learning), and 17 (Lecturers instill a long-term interest in students to stay afloat in the online learning process). [ABSTRACT FROM AUTHOR]

The Soputan Volcano monitoring system is currently being observed by the Center for Volcanology and Geological Disaster Mitigation (PVMBG), what PVMBG is doing is recording the seismic activity of the Soputan volcano. The PVMBG will inform the status of the volcano in the event of seismic activity. An early warning system is really important so that people are alert and able to independently evacuate in the event of an eruption. Along with technological developments, tools are needed that can provide seismic signals in the event of a catastrophic eruption. This study aims to create a tool that can detect seismic activity in the event of a volcanic eruption. The seismic information sent is based on the SMS gateway by developing the MPU-6050 module as a vibration sensor and IC LM35 as a temperature sensor. The remote monitoring system method uses data obtained from the vibration sensor which is received by the Arduino nano module and then sent using the GSM sim 800 L module. This GSM module is a transmitter that functions to send any data from the sensor into SMS form. The SMS data is in the form of nodes, so 1 node is equal to 1 time sending SMS. The data that has been sent is then received back by the GSM sim 800 L module which is a receiver that functions to receive any data that has been sent. And the data will be processed into the Delphi program and then displayed using a Personal Computer (PC). From the results of this design, the data displayed in the Delphi program is in the form of a graph. The parameter for the vibration sensor is the number of vibrations to time, and for the LM35 temperature sensor, the parameters are already in degrees Celsius (°C). The expected visual data is not fully real-time because there is a 5-second delay from the event time. Based on the test results obtained the detection process works well. [ABSTRACT FROM AUTHOR]

Iron is one of the elements of soil fertility where it presented in an area is influenced by natural processes and anthropogenic activities. The existence of iron in soil tends to form iron-bearing minerals which have magnetic properties, making them easier to identify physically. In this study, measurements and mapping of magnetic susceptibility were carried out on 80 ha of agricultural land in the Rurukan volcanic area, North Sulawesi in order to obtain an overview of variations in iron concentration at the studied location. Analysis of soil organic carbon was also carried out for seeing its relationship with magnetic susceptibility. The results showed that the magnetic susceptibility values on surface soil at the studied locations varied between (417.67 ± 1.85)×10−8 m3kg−1 to (1208.52 ± 1.85)×10−8 m3kg-1 with about 68% of the data being in the interval of 593.01 × 10−8 m3kg-1 until 769 × 10−8 m3kg-1. Compared to other areas with the same soil source, Rurukan agricultural land has the same or relatively higher magnetic susceptibility value. Based on the distribution of magnetic susceptibility values, it is interpreted that the southern and eastern parts of the study area are zones with relatively high Fe content. Several spots with significantly different susceptibility values were thought to be due to the influence of iron and C organic concentrations in the soil. In this case, the decrease in magnetic susceptibility was accompanied by an increase in the C organic content in the soil. The combination of topography and vegetation cover is thought to influence the susceptibility value at a point. [ABSTRACT FROM AUTHOR]

Magnetic mineral concentration, especially from the iron oxide class, is one of the important indicators in determining the potential iron sand natural resources. In this study, the magnetic measurement as well as X-ray spectroscopy analysis have been carried out in order to determine the concentration and microcrystalline characteristics of iron sand originating from four locations in the coastal area of North Sulawesi which are Lolan, Lalow, Hais, and Minanga. Magnetic properties study through measurement of saturation isothermal remanent magnetization (SIRM) confirmed by oxide composition obtained from X-ray fluorescence (XRF) observation showed that the iron sand sample from Lolan had the highest concentration of iron oxide minerals followed by samples from Hais, Lalow, and Minanga respectively. The percentage of iron oxide at these sites varied between 60.33 – 76.70 wt.%, implying that it was relatively competitive compared to the samples from other localities in Indonesia. Findings related to variations in crystal size and degree of crystallinity are closely related to the source and mechanism of iron sand formation at each study site. [ABSTRACT FROM AUTHOR]

Mount Soputan is one of the most active basaltic volcanoes in Indonesia and is located at the South region of the Tondano Caldera. Typical explosives for volcanoes with a basaltic magma composition are not common. Therefore, the spectroscopic characterization of volcanic ash is expected to extract important information related to the character of the Soputan eruption. The characterization of volcanic ash in this study focused on the eruption ash samples on January 4, 2016, February 6, 2016, and October 3, 2018. Before characterizing, ash particles are separated into three fractions: rough (> 125 µm), medium (125-70 µm), and fine fraction (<70 µm). Furthermore, ash samples were characterized using X-ray diffractometers (XRD), SEM-EDX, and FTIR in the Central Laboratory of Malang State University. The results of the XRD spectral peak analysis and comparison show that Soputan ash contains several types of minerals such as olivine forsterite (Ol), diopside (Di), augite (Au), maghemite (Ma), alkali feldspar (Af), feldspar plagioclase (Fp), anorthite (An), allophane (Al) and amorphous phase. The content of anorthite as a plagioclase mineral in ash samples confirms that Soputan magma is a new magma derived from shallower storage. The spectral characteristics of XRD indicate that the Soputan ash is rich in microcrystalline, which signifies that the magma of the three eruptions is also rich in crystals. The results of the EDX spectroscopy indicate that the Soputan magma is an alumina-rich basaltic magma. The FTIR spectrum supports basaltic properties in the presence of Si–O and Al-O clusters in bands 1134 cm-1 and 989 cm−1, while the O-H group and the H-O-H clusters in bands 3388 cm−1 and 1527 cm−1 are related to the existence of water molecules in magma that represent vesicles in magma. The SEM photosanalysis using ImageJ Software confirm that the Soputan ash contains two types, which are block particles and vesicular block particles. Soputan's magma during the January 2016, February 2016 and October 2018 eruptions is a more degassed magma due to the gas bubbles and rich crystals. Crystallinity and water content in magma are the main parameters that cause Soputan volcano to be explosive even though the magma is of basaltic type. [ABSTRACT FROM AUTHOR]

This paper offers a solution concept to develop an IA framework for Smart Government. Smart Government is an extended model of eGovernment and is an attempt to use developing technology to realise unfulfilled promises from previous modernisation initiatives such as new public management and eGovernment. Since the implementation of Smart Government relying on ICT, an approach to protect any threat to the information and systems and assure the business continuity in the event of an is needed. As a result, information assurance (IA) should be taken into consideration. The basic goal of information assurance is to protect businesses by lowering risks connected with data and information systems and assuring business continuity. However, although there are some studies focused on IA for eGovernment in Indonesia, there is no study so far that has focused on IA for Smart Government in Indonesia. This paper provides an overview of the relationship between Smart Cities, Smart Governance, and Smart Government. Furthermore, because Smart Government is an extended model of eGovernment, this paper also formulates a solution concept to develop an IA framework for eGovernment further to be an IA framework for Smart Government. The solution is, by using the triangulation method, an IA framework for Smart Government can be developed by identifying IA factors for eGovernment, IoT, Big Data, and Open Data. Using the solution concept, the future framework can be used to support IA implementation for Smart Government in Indonesia. [ABSTRACT FROM AUTHOR]

Online Transportation System in Indonesia is growing rapidly. The development of OTS usage is also growing, there is even research that discusses about most OTS users are people who are Undergraduate education and single. Mobility student users are also high with the need for those who travel to spend time with friends, duty, and other needs. Behind it all there is a problem in OTS in protecting passenger data, the case is the sale of hacked OTS accounts. This study looks at whether there is a correlation between users with privacy data perspectives and risk factors. In this study, SPSS was used to look at bivariate correlation values. This study used 110 respondents who will be analyzed and viewed the correlation value. There are 4 significant correlations between the background of respondents with privacy data perspectives and risk factors. [ABSTRACT FROM AUTHOR]

Increasing public services to the community is currently intensively carried out with the existence of e-Government. One of e-Government products in Indonesia is the SAKPOLE e-Samsat service. SAKPOLE e-Samsat service is an online service designed to facilitate the taxpayer in paying his motor vehicle tax accountability. The entire administrative area of Central Java can use this service, which one of them is the Karanganyar Regency. The success rate of implementing this technology influence by the readiness of its users to accept and use the technology. The purpose of this study was to determine the factors that influence behavioral intention to use the SAKPOLE e-Samsat service in Karanganyar Regency. This study used 104 respondents who will be analyzed using the variables in the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2) modified model. From this study, we found that Facilitating Condition, Performance Expectancy and Public Value had a significant positive effect on behavioral intention to use the SAKPOLE e-Samsat service, with Public Value is the most significant factor. It can conclude that the views of the people of Karanganyar Regency towards service providers have succeeded in increasing their capacity because of the usefulness of these services. [ABSTRACT FROM AUTHOR]

Creativity and communication are skills that need to be emphasized and taught to students to prepare them to face global challenges in the 21st century. The purpose of this study is to determine the achievement of students' creativity and communication skills in implementing physics learning at school and to test the instrument using the Rasch model analysis. This research is a survey research with the cross-sectional method. This study involved 46 respondents at SMAN 1 Lembah Melintang. The instrument used was a questionnaire with a total of 11 items. Based on data analysis, it was found that the level of students' creativity skills in learning physics was still low compared to students' communication skills. The results of the validity of the instrument using Rasch analysis showed that the value of raw variance data in the dimensionality table was 58.9% with a good category, so it can be concluded that the instrument in this study can be used to identify students' creativity and communication skills. [ABSTRACT FROM AUTHOR]

Maintain image quality is to conduct quality assurance routinely on CT scan. There are several important parameters in the assessment of image quality including CT number, uniformity and linearity, low contrast. The research method uses the variation of the parameters kVp and mA with restrictions on the use of parameters only in variations of 80, 100, 140 kVp with 192 mAs and 100, 200, 300 mAs with 120 kVp. previously considered the parameters of the Phillips Ingenuity CT scan application for the head examination routine and review as a reference. The results of the study for the CT number value between the recommended HU value and the measurement of the HU value performed have a value that is close to, so that for the CT number the CT scan is still in very good range, for the Uniformity HU value at the center of the phantom -0.854±0.402 and around the phantom (clockwise 12,3,6,9) -1,374±0,396, results are uniformity still within the tolerance range of±5 HU. Linearity HU value equation linear function with R2= 0.8692, indicating that a very strong correlation between the value of the attenuation coefficient HU. Quartile analysis of HU values for the kVp and mAs varies with the results of the second quartile value. Of the variations of mAs 100, 200 and 300 there were no significant differences in the values and tended to be the same, namely for 100 mAs Q2 values=92.04, 200 mAs Q2=93.62, 300 mAs Q2 values=92.05, while in the kVp variations there were significant differences i.e. 80 kVp Q2=99.12, 140 kVp Q2=89.59. So that the HU value is not affected by the mAs parameter, it can be said that there is no significant change in image quality from the contrast resolution; low contrast but it is influenced by the kVp parameter with a value of HU increase of about 36% when kV is increased by range of 60 kVp. [ABSTRACT FROM AUTHOR]

This paper presents the design, modeling and fabrication of the prototype of Hydro-Magneto-Electric- Regenerative Shock Absorber (HMERSA) with two electric generators in series for vehicle suspension. The designed HMERSA converts reciprocating linear motion of vehicle suspension into unidirectional fluid flow which turn the two electric generators in series and generate electricity. The HMERSA was modeled and simulated to study the damping force characteristic, the performance, and the generated power. Further, the prototype of HMERSA was manufactured and implemented in the vehicle suspension. The vehicle was tested on a bumping road. The vehicle body acceleration was measured as well as the generated voltage and current. The results are analyzed and discussed in this paper. [ABSTRACT FROM AUTHOR]

Currently, the metal working in manufacturing industry is growing rapidly, taking in mind that production activities cannot be separated from the use of machinery as a support for its operations. The excessive vibration will reduce the effectiveness of the engine, furthermore the engine will be irreparable. One way to reduce the excessive vibration from rotating shaft system at lathe machine is by using Radial Vibration Damper (RVD). This aims of this study are to reduce the vibration acting on a long thin shaft using RVD and to validate the experiment’s results and simulation’s results using the Independent T-test sample method. The position of RVD which is laid on a long thin shaft was varied. The working frequencies of the lathe machine were 320 rpm, 540 rpm, and 900 rpm. The results show that the simulation results correspond well to the experimental results. The maximum vibration reduction of a long-thin shaft occurred at the working frequency of 900 rpm for both the experimental method and the simulation method. The experimental results presented that the maximum vibration reduction of the shaft in the X-axis direction is 67.51% at point 4 (midspain) and the reduction in the Y-axis is 61.47% at point 3. While, the maximum reduction from simulation method occurred in the X-axis is 65.83% and in the Y-axis is 75.78%. [ABSTRACT FROM AUTHOR]

The metal working is the main sector of the manufacturing industry. There are many types of machine tools used in the manufacturing industry, one of them are drilling machine. Every working machine will definitely produce the vibration. The vibration that comes from a working drilling machine can reduce the effectiveness of the machine and cause the damage of machine components. And eventually reduce company productivity. The vibration from the drilling machine can be overcome by using Dynamic Vibration Absorber (DVA). The main system of DVA is the mass of absorber and the spring. This study is about an experimental study of Translational Mass Vibration Absorber (TMVA) which is one of Dynamic Vibration Absorber (DVA) types. TMVA is designed to be able to reduce the vertical vibrations caused by the rotational speed of drilling machine. The drilling machine used is Kao Ming Machinery Industrial Co., Ltd type KMR-700DS. TMVA has only vertical direction movement. TMVA is designed in the cylindrical shells made of acrylic. The TMVA consists of the absorber mass and a spring. The main systems of the drilling machine which were being observed in this study were the workpieces and the drill bits. TMVA was only placed on the workpiece during the drilling process. There were 2 variations used, that were the drill size variations and the TMVA mass ratio. The experiment carried out in two different conditions, that were the main system without TMVA and the main system with TMVA. The results are about vibration acceleration response, percentage reduction, surface of the drilling material, and the accuracy level of the drilling diameter for each variation used. TMVA can reduce vibration at the rotational speed of 441 rpm and at the feeding speed of 0.07 mm/rev. Based on the experiment done, it can be concluded that the addition of 1/20 mass of absorber from the workpiece mass represented by 2 coins can effectively reduce the vibration in 12 mm drill size by 31.91%. TMVA also reduce the chatter effect and increase the accuracy level as indicated by the magnitude of the difference of drilling diameter without TMVA and with TMVA optimally at 0.15 mm. [ABSTRACT FROM AUTHOR]

The CPVA (Cantilever Piezoelectric Vibration Absorber) is a mechanism that combines working principles of DVA and energy harvesting to reduce vibration while generating voltage. The system’s response that need to be reduced by the CPVA is a plat as a primary mass which has 3 degree-of-freedom those are translation, rolling, and pitching vibration direction. The optimum configuration of this mechanism has the objective in order to reach a maximum percentage of reduction while generating voltage. The variation of piezoelectric’s amount and several nodes position where its mechanism is installed on the primary system need to be optimally selected to implement satisfactory performance. Simulation provides valuable insights in dynamical characteristics in each nodes and results the optimum value of the reduction and voltage generation in the 8th node position with the amount of 100 pieces of piezoelectric, which succeed for reducing translational, rolling, and pitching direction up to 79.8%; 76.1%; and 79.69% respectively. [ABSTRACT FROM AUTHOR]

The high generated power of the wind turbine requires stronger wind which is usually at high altitudes. The high constructions are vulnerable to external load such as strong wind. Therefore, it requires the system which can reduce the vibration caused by the wind force. Furthermore, the different form of the wind turbine’s tower would affect the vibration of the wind turbine. The aim of this study is to compare the responses of vibration in three different form of wind turbine’s tower. The effects of Tuned Mass Damper to each structure vibration were analyzed. The study was conducted both simulation and experimental method in a laboratory scale of the wind turbine model. The simulation results show that the installation of TMD on the wind turbine model reduces the acceleration of the nacelle’s mass at the frequency of 3 Hz. The optimum installation of TMD occurs in straight tower type which the addition of TMD could reduce the vibration of the nacelle mass in each frequency variation. The stiffness constant of the TMD affects the vibration reduction of the nacelle mass more than the TMD mass variation. [ABSTRACT FROM AUTHOR]

This paper presents the modeling and analysis of Regenerative Shock Absorber (RSA) using ball screw mechanism. The RSA design converts the reciprocating linear motion of vehicle suspension using ball screw. Bevel gear and one-way bearing convert bidirectional rotation to unidirectional rotation and the power will be simultaneously generated. The RSA ball screw was modeled and simulated to study the characteristics, performance, and power generated. The damping force provided by RSA was analyzed with various spur gear ratios to know the damping force value. The quarter car model was simulated to know the characteristic of a vehicle body when RSA is installed. The model is based on SUV with a spur gear ratio of 1.25. With various excitation frequency which proportional to vehicle speed, the RMS power generated was 21.7 W and maximum power 40 W at 60 km/h. The RMS vehicle body vertical acceleration is 1.71 m/s2 and reduce 8.6% than RSA hydraulic type in previous work. [ABSTRACT FROM AUTHOR]

This present study describes the distribution and pattern of polyprenols and dolichols from fruits and rinds of selected mangrove plants namely Barringtonia racemosa, Thespesia populnea, and Xylocarpus granatum that were analysed using two-plate thin layer chromatography (2P-TLC) method. In the fruits and rinds organs, two-types the pattern of polyprenols and dolichols were obtained. Type-I, having the prevalence of dolichols over polyprenols, was detected in fruits of B. racemosa and X. granatum fruits and rinds. Type-II, the occurrence of both polyprenols and dolichols, was traced in fruits and rinds of T. populnea and rinds of B. racemosa. In all tissues of fruits and rinds of B. racemosa, T. populnea, and X. granatum were occurred chain length of dolichol (C50-C110, C60-C110), (C65-C100, C80-C95), and (C80-C90, C80-C90), respectively. Whereas the polyprenol occurred only in fruits and rinds of T. Populnea (C65-C90, C55-C65), and B. racemosa rinds (C60-C110). The composition of polyisoprenoid in fruits as well as rinds of B. racemosa, T. populnea, and X. granatum is first study to extend our previous finding of the profile and characterization of polyisoprenoid in mangrove plants. [ABSTRACT FROM AUTHOR]

Polyisoprenoid (polyprenols or dehydrodolichols and dolichols) content and composition of four true mangrove plants namely Excoecaria agallocha, Lumnitzera racemosa, Rhizophora apiculata, and R. lamarkii were investigated with particular emphasis on leaf senescence. The distribution and occurrence of polyisoprenoids was analyzed using the two-plate thin layer chromatography (2P-TLC) method. The age of the leaves was divided into young leaf, leaf, and yellow leaf. In the leaves, the distribution of polyisoprenoid was found to show the presence of both polyprenols and dolichols. The occurrence of ficaprenols (C50-C55) was observed in young leaves and leaves of the mangrove samples studied. On the other hand, dolichol contents were not altered in the leaves with senescence. By contrast, longer polyprenols were found in yellow leaves of E. agallocha, L. racemosa, and R. apiculata. In addition, it should be noted that there were changes to the polyprenols in leaf senescence identified. Furthermore, the formation of ficaprenols, longer polyprenols, and dolichols was modulated in the mangrove plants. These findings suggest that the accumulated polyprenols in the yellow leaves may be due to the catalyzation process that converts ficaprenols into longer polyprenols. [ABSTRACT FROM AUTHOR]

Bintaro (Cerbera manghas L, Apocynaceae) is a mangrove plant that has been described to have several important biological properties and pharmacological activities. In this study, the vegetative organs (leaves, roots, and stems) and the generative tissues (flowers and fruits) were analysed using two-plate thin layer chromatography to investigate the polyisoprenoid (polyprenol or dehydrodolichol and dolichol) profiles. It was found that in the vegetative tissues, there was two types (I and II) of polyprenols and dolichols detected. Type-I having a prevalence of dolichols over dehydrodolichols, was traced in the roots and stems, and type-II, having an occurrence of both polyprenols and dolichols, was found in the leaves. In contrast, in the generative organs only type-I was detected. Taken together, four out of five tissues tested showed a predominance of dolichols over polyprenols, suggesting the existence of polyprenol reductase in C. manghas. The varying polyisoprenoids in the different tissues of C. manghas indicating that these compounds have chemotaxonomic significance in C. manghas. [ABSTRACT FROM AUTHOR]

This paper reports the result of modelling and analysis of the pressure response and the regenerated energy of two different mechanism of energy regenerating shock absorber with 1) Single Input Hydarulic Cylinder-Single Output Generator (SISO), and 2) Double Input Hydraulic Cylinder-Single Ouput Generator (DISO). The recently developed and researched hydraulic based regenerative shock absorber uses SISO concept, which convert the vibration energy of one suspension into electricity using one magneto-electric generator.In this research, the new concept of converting vibration energy from two input suspesion simultaneously with one generator, DISO is proposed to improve the continuity of energy supply and the output power. The SISO and DISO are mathematicaly modelled and simulated. For SISO, the simulated inlet pressure shows a periodic trend with maksimum pressure of 1.2 MPa. This inlet pressure can produce hydarulic motor's maximum output torque of 1-1.5 Nm. Meanwhile, DISO can produce inlet pressure with maksimum pressure of 1.2 MPa and hydarulic motor's maximum output torque of 1.2-1.6 Nm. This simulation results show that DISO has better performance than SISO. The detail results are discussed in this paper. [ABSTRACT FROM AUTHOR]

Shock absorber is designed to convert the kinetic energy from impact into heat energy that is dissipated. The dissipated energy that is produced by conventional shock absorber is wasted. The aim of this paper is to design the shock absorber that can damp the impact and can harvest energy at the same time. It is called Hydro-Magneto-Electric Regenerative Shock Absorber (HMERSA). This research simulated the HMERSA that applied on a front and rear suspension system of a car. The car speed was varied from 0 km/h to 80 km/h. The phase difference of front and rear suspension's input were 0° and 90°. The results show that the highest power generated is 165 Watt at car speed of 80 km/h and occurred when the phase difference was 0°. [ABSTRACT FROM AUTHOR]

CPVA (Cantilever Piezoelectric Vibration Absorber) is a mechanism that can reduce vibration and produce electricity. Its working principle combines DVA (Dynamic Vibration Absorber) and Energy Harvesting with Piezoelectric cantilever method. By pairing the CPVA mechanism on the main system, the vibration energy in the main system will be damped then it can be converted into electrical energy. The amount of reduction and electrical energy generated by CPVA mechanism can be optimized by regulating the use of Cantilever Piezoelectric on CPVA mechanism. This study stated that the optimum CPVA mechanism is CPVA which uses the number of Piezoelectric cantilever as 1400-2400 pieces and it is operated at natural frequency 20.61 rad / s with amplitude 0.3 m and 0.35 m. The resulting of vibration reduction is 20.28% up to 22.75%. And the electrical energy generated is 2.17E-7 to 5.78E-7 watts. [ABSTRACT FROM AUTHOR]

The purpose of this study is to reduce the vibration in translational and rotational motion with Dynamic Vibration Absorber. The study is conducted by simulation and experimentally to analyze the vibration from main system without DVA and main system with DVA. The DVA prototype used in experiment consists of an electric motor, disc, unbalance mass, absorber mass, belt, main cantilever, box, beam, and absorber cantilever. The distance ratio (rL) is varied by moving the absorber cantiléver. The range of excitation frequency are from 0 Hz to 30 Hz. The ratio of absorber mass to system mass is 0.05. The simulation method is building block diagram from the state variable equation which is achieved from free body diagram of main system without DVA and main system with DVA. The results show that the simulation result has similarity to the experiment result. The displacement increases by the increasing of the distance between center of gravity of absorber and center of gravity of beam. The optimum reduction of vibration occurred at rL=4. [ABSTRACT FROM AUTHOR]

Along with the rapid development of technology, the world of education is certainly directed to be able to create competent human resources who will play a role in creating new technologies in the future. For this reason, learning is expected to increase student motivation. Students who are motivated in learning will certainly easily spend their time honing their abilities. In addition to learning motivation, spatial ability is also very much needed as a basic skill that students must have in new days. Of course the two variables can be developed through several learning approaches. One of them is the use of virtual reality technology. This research aims to show why virtual reality can improve student motivation and spatial ability. Data was obtained through literature reviews from reputable scientific journals and books. From the results of the study, it was found that virtual reality increases student motivation and spatial ability. This is inseparable from the concept of virtual reality technology that combines virtual access that looks real so as to make learning more interesting. [ABSTRACT FROM AUTHOR]

An increasing demand for oil and gas production undoubtedly triggered innovation in exploration studies to find new hydrocarbon reservoir. Low-frequency passive seismic method named Hy MAS (Hydrocarbon Microtremor Analysis) is a new method invented and developed recently by Spectraseis which provide a quick look to find new hydrocarbon reservoir prospect area. This method based on empirical study which investigated an increasing of spectra anomaly between 2 - 4 Hz above reservoir but missing from the measurement distant from the reservoir. This method is quite promising because it has been used as another DHI (Direct Hydrocarbon Indicator) instead of active seismic survey which has some problem when applied in sensitive biomes. Another advantage is this method is completely passive and does not require seismic artificial excitation sources. In this study, by utilizing many attributes mentioned in the latest publication of this method, we try to localize new hydrocarbon prospect area outside from the proven production field. We deployed 63 stations of measurement with two of them are located above the known reservoir production site. We measured every single attribute for each data acquired from all station and mapped it spatially for better understanding and interpretation. The analysis has been made by considering noise identification from the measurement location and controlled by the attribute values from the data acquired by two stations above the reservoir. As the result, we combined each attribute analysis and mapped it in weighted-scoring map which provide the level of consistency for every single attribute calculated in each station. Finally, the new reservoir location can be suggested by the station which has a weighted-score around the values from the two production reservoir stations. We successfully identified 5 new stations which expected to have good prospect of hydrocarbon reservoir. [ABSTRACT FROM AUTHOR]