Taiwan Association of Engineering and Technology Innovation: E-Journals
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Area-Construction Algorithms Using Tangent Circles
Get PDFComputer aided geometric design employs mathematical and computational methods for describing geometric objects, such as curves, areas in two dimensions (2D) and surfaces, and solids in 3D. An area can be represented using its boundary curves, and a solid can be represented using its boundary surfaces with intersection curves among these boundary surfaces. In addition, other methods, such as the medial-axis transform, can also be used to represent an area. Although most researchers have presented algorithms that find the medial-axis transform from an area, a algorithm using the contrasting approach is proposed; i.e., it finds an area using a medial-axis transform. The medial-axis transform is constructed using discrete points on a curve and referred to as the skeleton of the area. Subsequently, using the aforementioned discrete points, medial-axis circles are generated and referred to as the muscles of the area. Finally, these medial-axis circles are blended and referred to as the blended boundary curves skin of the area; consequently, the boundary of the area generated is smooth
Path Control iRobot Create2 Based Sensors
Get PDFRobots become a part of humans’ daily lives. They work faster, more accurate, and tireless compared to humans. As technology developes, robots are more capable of serving people in more tasks than before. The objective of this study is to explain the methodology of controlling iRobot Create2 by using Arduino Uno to command iRobot Create2 to use operation codes. Instead of using a brute-force way to control the robot motion by commands, which may cause the whole path to go wrong if only one command is deflected. However, with the sensors, the robot can adjust the direction path despite the deviation. The Arduino Uno communicates with iRobot through the serial communication using SoftwareSerial. Arduino requests a sensors data from iRobot and calculates deviations in order to adjust the path. The study includes the general knowledge of Arduino control iRobot Create2 based on the robot’s sensors and the detailed process of completing the first round of iRobot Competition
Development and Characterization of Thermal Insulation Geopolymer Foams Based on Fly Ash
Get PDFThe main purpose of the article is to present the differences in the parameters of geopolymer foams obtained in the same way, which is associated with difficulties in controlling the foaming process. Difficulties in controlling the foaming process of geopolymers are the direct reason for the lack of implementation of such materials nowadays. The article shows the results for experimental research, especially research into insulation, physical, and mechanical properties for the designated foamed materials. Microspheres (75%), sand (5%) and fly ash (20%) were used to produce foamed geopolymers. Hydrogen peroxide was the foaming agent. Heat conduction coefficients of 0.08-0.07 W/mK were obtained. The material density was obtained at the level of 363-375 [kg/m3] and the compressive strength was 520-683 [kPa]. The results showed that geopolymers can be a good alternative to conventional insulation materials, but the foaming technology should be developed so that it is stable and allows for reproducible material parameters
Velocity Field around a Rigid Flapping Wing with a Winglet in Quiescent Water
Get PDFThis study investigated the effect of a winglet on the velocity field around a rigid flapping wing. Two-dimensional particle image velocimetry was used to capture the velocity field of asymmetric one-degree-of-freedom flapping motion. A comparison was conducted between wings with and without a winglet at two flapping frequencies, namely 1.5 and 2.0 Hz. The effect of the winglet on the velocity field was determined by systematically comparing the velocity fields for several wing phase angles during the downstroke and upstroke. The presence of a winglet considerably affected the flow field around the wingtip, residual flow, and added mass interaction. The added mass was lower and residual flow was weaker for the wings with a winglet than for the wings without a winglet. The added mass and velocity magnitudes of the flow field increased proportionally with the flapping frequency
Cross Layer Based Cooperative Communication Protocol for Improving Network Performance in Underwater Sensor Networks
Get PDFFor underwater sensor networks (USNs), cooperative communications have been introduced to improve network performance with the help of relay nodes. The previous cooperative communications select the best relay node on a hop-by-hop basis. Therefore, they have limitations in improving performance. In order to get better performance, a cooperative communication protocol based on the cross layer is proposed in this paper. The proposed protocol uses the information provided by a routing protocol at the network layer for the erroneous data packet delivery. It selects one with the minimum routing cost among relay candidate nodes. The routing protocol in the selected relay node provides the MAC layer with the address of the next hop node on the path to the sink node. Then, the MAC layer in the selected relay node forwards the erroneous data packet to the next hop node rather than a receiver node. Performance studies are carried out through simulation. Simulation results show that the proposed protocol has about 21.8% lower average delay and about 14.4% lower average number of nodes passed than the previous protocol, regardless of the maximum transmission range
Study of Primary and Internal Resonance on 3D Free-Free Double-Section Beam
Get PDFThis work investigates the primary resonance and internal resonance of a double-section beam with cubic nonlinearities. This model can be applied in a wide range of engineering problems, such as rocket and missile structures. Even space technology has been developed for decades; several nonlinear properties deserve further study, especially, for the internal resonance. The method of multiple scales (a perturbation technique) is employed to analyze this nonlinear problem. This study focuses on finding the forcing conditions of this 3D double-section beam to trigger the often-ignored internal resonance or prime resonance in rocket structures. A primary resonance is found on a uniform free-free beam at certain flight speed. The three-to-one internal resonance of the double-section beam occurs within the first and the second modes in the diameter ratio of 1/0.75 with the length ratio of 0.33 or 0.51. The semi-analytical results are verified by the time marching numerical method
Connectivity Investigation of Channel Quality-Based Adaptive Gossip Flooding Mechanism for AODV
Get PDFTo address the “broadcast storm” problem associated with flooding-based route discovery mechanism of reactive routing protocols, probabilistic approaches are suggested in the literature. In the earlier work, Gossip flooding mechanism of Haas et.al. was extended with signal quality, to propose channel quality based adaptive gossip flooding mechanism for AODV (CQAG-AODV). Following the cross-layer design principle, CQAG-AODV algorithm tried to discover robust routes, as well as address the “broadcast storm” problem by controlling the rebroadcast probability of Route request (RREQ) packets on the basis of signal strength experienced at the physical layer. This paper investigates the connectivity of CQAG-AODV through theoretical and simulation analysis. Results show that, by accounting the signal strength in the route discovery process, not only does the proposed algorithm floods a lesser number of route requests and controls the broadcast storm, but also maintains a higher level of connectivity to offer high packet delivery ratio; independent of network density and node mobility. Moreover, due to controlled routing overhead and robust route discovery, channel quality based adaptive flooding mechanism offers fringe benefit of energy efficiency as well. CQAG-AODV thus proves its suitability in a variety of use cases of multi-hop ad hoc networks including WSNs and VANETs
Free Vibration Frequency of Thick FGM Circular Cylindrical Shells with Simply Homogeneous Equation by Using TSDT
Get PDFThe objective of this study is to provide the frequency solutions of free vibration in thick FGM circular cylindrical shells by mainly considering both shear correction coefficient and nonlinear coefficient term. This paper investigates the effects of third-order shear deformation theory (TSDT) and the varied shear correction coefficient on the free vibration of thick functionally graded material (FGM), the circular cylindrical shells with simply homogeneous equation under thermal environment. The approach of derivations are given as follows, the varied value of shear correction coefficient is included in the simple homogeneous equation. The nonlinear term of displacement field of TSDT is also included to derive the simply homogeneous equation, some reasonable simplifications in the elements of homogeneous matrix under free vibration of thick FGM circular cylindrical shells are assumed, thus, the natural frequency can be found. Three parameters effect on the frequency of thick FGM circular cylindrical shells are computed and investigated, they are nonlinear coefficient c1 term, environment temperature and power law index. There are some main conclusions obtained, generally the natural frequency results are in decreasing value with the mode shape numbers for the thicker circular cylindrical shells. The values of natural frequencies are also affected by the nonlinear coefficient term
The Emergence and Growth Path of Shanzhai Firms
Get PDFShanzhai refers to a set of dynamic strategies for firms to grow out of counterfeiting. Shanzhai firms have traditionally been perceived as counterfeiters from the emerging economies producing cheap and low-quality products. This trend has changed in recent years when Shanzhai firms have grown into market leaders and have introduced leading technologies and applications. This paper focuses on the growth of Shanzhai firms by exploring how Shanzhai firms and Shanzhai industries emerged. We further investigate the context that supports the emergence of Shanzhai firms into market leaders. We leverage two case studies using the growth path of two market leaders in their respective industries to illustrate the two paths leading to the emergence of Shanzhai firms. We attempt to show that although Shanzhai firms start out with low legitimacy, these firms grow their legitimacy over time by building their core competitiveness in their respective industries
Design Wind Speed Estimation for Long Span Bridges in Korean Southern and Western Coasts
Get PDFRecently, many long-span cable supported bridges, including the cable stayed bridges and the suspension bridges, have already been constructed or are planned for construction. Because the meteorological values used to estimate the wind load for designing the long-span bridges were based on data from the 1960s through 1995 in Korea, it is necessary to reconsider the proper design wind load for long-span bridges. In this paper, the research area is confined to the southern and western coasts of Korea where many long-span bridges have been built. The method of moment and the least-squares method are used to estimate the expected wind speeds of a 100-year return period for girder bridges; Gumbel’s distribution is used to estimate the expected wind speeds of a 200-year return period for long-span bridges. As the return period wind speed on the land surface is revised because of recent high-speed velocity, the revised return period wind speed is increased by 17%. The compatibility of return period wind speed is also evaluated using the RMS (root mean square) error method. This paper concludes that the least-squares method is more compatible than the method of moment for the case of the southern and western coasts of Korea