Applied Mechanics and Materials Vol. 776

Abstract: There are so many equipment using cylinder in its application, such as bridge support column, smoke chimney, pole pillar of offshore oil drilling etc. When those kind of equipment is affected by air flow continuously, it would reducing the strength of those equipment construction. This strength reduction is caused by the drag force that is emerged due to the air flow and its direction are having the same direction with flow direction. So that it is necessary to do something to reduce the drag, one of it is by adding the rectangular ring at the cylinder surface. The rings is placed at the cylinder surface in 10⁰ sloping position and then its ring distance would be varied. The aim of this research is to discover the influences of distance variation between the ring with sloping position on the cylinder surface to the drag coefficient. This research is conducted in the wind tunnel that consist of blower, pitot pipe, U manometer, inclined manometer, digital weight, cylinder, quadrangular rings (attached on the cylinder). The cylinder is placed in vertical position within the distance between the rings is varied as L/D = 0.5, 0.67, 0.83, 1.00, and 1.17. The Reynold number based on silinder diameter D = 60 mm is Re = 3.64 X 10⁴ . Pressure distribution is determined by measuring cylinder surface pressure at 36 points with 10⁰ interval. The result of this research showed that the lowest drag coefficient value occurs at the distance between the ring of L/D = 0.5 is 0.485. The large decreasing of the drag coefficient compare to without rings is 43.5%.

Abstract: This paper introduces auto tuning of proportional-integral-derivative (PID) controllers of DC motor using particle swarm optimization (PSO) method. The DC motor was modeled in Simulink and PSO was implanted on FPGA “cyclone IV E” using the soft processor NIOS II. The results were efficient in reducing the steady state error, settling time, rise time and maximum overshoot in speed control of a DC motor.

Abstract: The ability of mobile robot to move about the environment from initial position to the goal position, without colliding the obstacles is needed. This paper presents about motion planning of mobile robot (MR) in obstacles-filled workspace using the modified Ant Colony Optimization (M-ACO) algorithm combined with the point to point (PTP) motion in achieving the static goal. Initially, MR try to plan the path to reach a goal, but since there are obstacles on the path will be passed through so nodes must be placed around the obstacles. Then MR do PTP motion through this nodes chosen by M-ACO, in order to form optimal path from the choice nodes until the last node that is free from obstacles. The proposed approach shows that MR can not only avoid collision with obstacle but also make a global planning path. The simulation result have shown that the proposed algorithm is suitable for MR motion planning in the complex environments with less running time.

Abstract: This paper presents a method of solving the problem of mobile robot motion control using a model predictive controller designed using Laguerre functions. A linear model of the two-wheeled nonholonomic robot is used. This linear model is obtained by converting the nonlinear model in the Cartesian system to a polar one. This change is preferred because it is easier to work with the linear model than its corresponding nonlinear one. Simulation results obtained from MATLAB showing that Laguerre-based MPC (LMPC) performs well are presented.

Abstract: The waterwheel is the main component in the energy conversion process of micro-hydro power. The amount of energy converted by the waterwheel depends on its model, blade shape, location, and position. Our objective in this study was to identify the waterwheel characteristics that yield optimal efficiency. We designed and created three prototype waterwheel models, tested them, and collected data for analysis. Measurement data related to various adjustments in the position and angle of the nozzle with respect to the blades. The results show that triangular rather than straight or curved blades yielded the highest efficiency, but that the location characteristics strongly influence the optimum angle positions of the nozzle etc.

Abstract: This paper describes an impairment commonly encountered in an OFDM system that must be considered in the design that is peak average power ratio (PAPR). In these studies, a statistical approach to analysing PAPR is suggested. The PAPR statistics of OFDM and VFFT-OFDM are studied by simulation of the statistical distribution of the quantity that is the Complementary Cumulative Distribution Function (CCDF) of the PAPR. The simulation results show that the simulated CCDF of PAPR, the 1% PAPR of OFDM is about 11.40 dB, whereas for VFFT-OFDM this rises to less than 3% of the time. Simulations show that by employing VFFT in OFDM system results in a 0.55 dB deterioration in the PAPR 1% of time.

Abstract: Applying the same principle behind the Ad-hoc weighing used in fusing data from two inexpensive GPS and an electronic compass (EC) brought up the problem of numerous conditions when trying to fuse data from three GPS devices. Fusing data from two GPS and one EC required at least thirty-two (32) conditions while using three GPS would require 182 conditions that would have entailed a complex set of programming codes. Fuzzy logic was explored as a possible candidate to replace the hard-coding of if-then-statements but still perform the ad-hoc algorithm as desired. The GPS Fix and HDOP (horizontal dilution of precision) values are utilized to derive the corresponding weight to be assigned to the individual GPS as well as the overall fused GPS data. Experimental tests using actual GPS data showed the effectivity of the proposed method.

Abstract: This paper describes the implementation of data tree structure for the application information system of ulam bebantenan. Ulam bebantenan complementary tool part of the offerings at a ceremony Hindusm in Bali. The structure of the data tree displays information about the data contained in a kind of ulam bebantenan. The data information is displayed in the form of the name of a ulam, ulam’s function, description of ulam, recipe, until the methode of cooking of ulam bebantenan. Application of information system is built to be run on mobile devices with the Android operating system. This application provides information about the description text, images and video related to bebantenan side dish in Bali. Users acquire data with information from the application access to the server system.

Abstract: Bali is a small and unique island, which stores various indigenous wealth and culture. One of the customs and cultural heritage is the presence of the holy places of Hindu temple that is lying scattered all over the island of Bali as a worship place of God. Known as Thousand Temples Islands, Bali island has many sacred places are grouped into General temple, Territorial temple, Functional temple and Kawitan temple based on the character and nature^[1]. Hindu tradition known as Tirtayatra done by praying to the temples. Aside from being a holy place, the temple is also a tourist attraction for visitors in Bali. Large numbers, spread location lead to difficulty in the location searching and each temple can be composed of several buildings give problems in data collection and maintenance of information. A geographically-based system is needed to solve these problems. By using Google Maps and web programming technologies, this system will be able to help the hindus and other visitors to determine their location and the location of the temple. In addition, this system can also be accessed anywhere with an internet connection.

Abstract: The dependence of human being on fossil fuels has decreased significantly the conventional energy resources. To overcome this problem it is required alternative substitute fuels which are cheap and accessible which biogas is one of the fuels. Nevertheless, the use of biogas has not yet been maximized because of the low calorific value which is produced from the process without purification. The circulated water absorption method is one mean of effective biogas purification. Under this method it is expected to increase the level of methane (CH₄) and to reduce both the level of carbon dioxide (CO₂) and hydrogen sulfide (H₂S). In order to obtain the aim, the research was carried out under variations of water and biogas volumetric flow rate. The results show that the highest quality of biogas produced was under the variation of water volumetric flow rate of 15 lt/min with biogas volumetric flow rate of 1 lt/min which increased the level of methane (CH₄) from 59.36 % to 62.8 % and decreased the carbon dioxide (CO₂) content from 33.53 % to 26.8 %, and hydrogen sulfide (H₂S) from 208.33 to 86 ppm. Lower biogas and water volumetric rates allowed longer contact between biogas molecule and absorbent. This resulted in an opportunity for absorbent more active to dissolve carbon dioxide and hydrogen sulfide in biogas. These compounds then flowed outward of the scrubbing unit along with the absorbent. The research proved that the raw biogas purification by circulated water scrubbing method was an effective mean in enhancing the quality of biogas.