Current Issue : April - June Volume : 2020 Issue Number : 2 Articles : 5 Articles
Digital watermarking technology is an effective method for copyright protection of digital\ninformation, such as images, documents, etc. In this paper, we propose a high capacity text image\nwatermarking technique against printing and scanning processes. Firstly, this method obtains the\ninvariant in the process of printing and scanning under the mathematical hypothesis model of\nprint-scan transformation. Then based on the print-scan invariant, the Fourier descriptor is used\nto flip the trivial pixel points with high frequency information on the character boundary. Next,\nconsidering the resolution of the print-scan equipment and its influence on the print-scan invariant,\na quadratic quantization function is proposed to embed watermark information of multiple bits\nfor a single character. Finally, the QR code (Quick Response code) is researched, which has large\ninformation capacity, robust error correction ability and high decoding reliability. By using the QR\ncode as the watermark information, we can reduce the impact of bit error rate during watermark\nextraction, and the robustness of the watermark information can be improved. The experimental\nresults show that the proposed text watermarking algorithm has the advantages of anti-print scanning,\nanti-scaling, large capacity and good visual effects....
A satellite spacecraft is generally composed of a central Control and Data Management Unit (CDMU) and several instruments,\neach one locally controlled by its Instrument Control Unit (ICU). Inside each ICU, the embedded boot software (BSW) is the\nvery first piece of software executed after power-up or reset. The ICU BSW is a nonpatchable, stand-alone, real-time software\npackage that initializes the ICU HW, performs self-tests, and waits for CDMU commands to maintain on-board memory and\nultimately start a patchable application software (ASW), which is responsible for execution of the nominal tasks assigned to the\nICU (control of the satellite instrument being the most important one). The BSW is a relatively small but critical software item,\nsince an unexpected behaviour can cause or contribute to a system failure resulting in fatal consequences such as the satellite\nmission loss. The development of this kind of embedded software is special in many senses, primarily due to its criticality, realtime\nexpected performance, and the constrained size of program and data memories. This paper presents the lessons learned in\nthe development and HW/SW integration phases of a satellite ICU BSW designed for a European Space Agency mission....
An important area in precision agriculture is related to the efficient use of chemicals\napplied onto fields. Efforts have been made to diminish their use, aiming at cost reduction and\nfewer chemical residues in the final agricultural products. The use of unmanned aerial vehicles\n(UAVs) presents itself as an attractive and cheap alternative for spraying pesticides and fertilizers\ncompared to conventional mass spraying performed by ordinary manned aircraft. Besides being\ncheaper than manned aircraft, small UAVs are capable of performing fine-grained instead of the\nmass spraying. Observing this improved method, this paper reports the design of an embedded\nreal-time UAV spraying control system supported by onboard image processing. The proposal uses\na normalized difference vegetation index (NDVI) algorithm to detect the exact locations in which\nthe chemicals are needed. Using this information, the automated spraying control system performs\npunctual applications while the UAV navigates over the crops. The system architecture is designed\nto run on low-cost hardware, which demands an efficient NDVI algorithm. The experiments were\nconducted using Raspberry Pi 3 as the embedded hardware. First, experiments in a laboratory were\nconducted in which the algorithm was proved to be correct and efficient. Then, field tests in real\nconditions were conducted for validation purposes. These validation tests were performed in an\nagronomic research station with the Raspberry hardware integrated into a UAV flying over a field of\ncrops. The average CPU usage was about 20% while memory consumption was about 70 MB for high\ndefinition images, with 4% CPU usage and 20.3 MB RAM being observed for low-resolution images.\nThe average current measured to execute the proposed algorithm was 0.11 A. The obtained results\nprove that the proposed solution is efficient in terms of processing and energy consumption when\nused in embedded hardware and provides measurements which are coherent with the commercial\nGreenSeeker equipment....
The geometric tolerance of notching machines used in the fabrication of components for\ninduction motor stators and rotators is less than 50 microm. The blunt edges of worn molds can cause\nthe edge of the sheet metal to form a burr, which can seriously impede assembly and reduce the\nefficiency of the resulting motor. The overuse of molds without sufficient maintenance leads to\nwasted sheet material, whereas excessive maintenance shortens the life of the punch/die plate.\nDiagnosing the mechanical performance of die molds requires extensive experience and finegrained\nsensor data. In this study, we embedded polyvinylidene fluoride (PVDF) films within the\nmechanical mold of a notching machine to obtain direct measurements of the reaction forces\nimposed by the punch. We also developed an automated diagnosis program based on a support\nvector machine (SVM) to characterize the performance of the mechanical mold. The proposed cyberphysical\nsystem (CPS) facilitated the real-time monitoring of machinery for preventative\nmaintenance as well as the implementation of early warning alarms. The cloud server used to gather\nmold-related data also generated data logs for managers. The hyperplane of the CPS-PVDF was\ncalibrated using a variety of parameters pertaining to the edge characteristics of punches. Stereomicroscopy\nanalysis of the punched workpiece verified that the accuracy of the fault classification\nwas 97.6%....
Recently, thanks to the miniaturization and high performance of commercial-off-the-shelf\n(COTS) computer systems, small satellites get popular. However, due to the very expensive launching\ncost, it is critical to reduce the physical size and weight of the satellite systems such as cube satellites\n(CubeSats), making it infeasible to install high capacity batteries or solar panels. Thus, the low-power\ndesign is one of the most critical issues in the design of such systems. In addition, as satellites\nmake a periodic revolution around the Earth in a vacuum, their operating temperature varies greatly.\nFor instance, in a low earth orbit (LEO) CubeSats, the temperatures vary from 30 to -30 degrees\nCelsius, resulting in a big thermal cycle (TC) in the electronic parts that is known to be one of the\nmost critical reliability threats. Moreover, such LEO CubeSats are not fully protected by active\nthermal control and thermal insulation due to the cost, volume, and weight problems. In this\npaper, we propose to utilize temperature sensors to maximize the lifetime reliability of the LEO\nsatellite systems via multi-core mapping and dynamic voltage and frequency scaling (DVFS) under\npower constraint. As conventional reliability enhancement techniques primarily focus on reducing\nthe temperature, it may cause enlarged TCs, making them even less reliable. On the contrary,\nwe try to maintain the TC optimal in terms of reliability with respect to the given power constraint.\nExperimental evaluation shows that the proposed technique improves the expected lifetime of the\nsatellite embedded systems by up to 8.03 times in the simulation of Nvidiaâ??s Jetson TK1....
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