• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1377-1399
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• 2020

In search and rescue mission, micro aerial vehicles (MAVs) are typically used to capture image and video from an aerial perspective and transfer the data to the ground station. Because of the power limitation, a cluster of MAVs are required for a large search area, hence an ad-hoc wireless network must be maintained to transfer data more conveniently and fast. However, the unstable link and the intermittent connectivity between the MAVs caused by MAVs' movement may challenge the packet forwarding. This paper proposes a delay tolerant packet forwarding algorithm based on location estimation for MAV networks, called DTN_est algorithm. In the algorithm, ferrying MAVs are used to transmit data between MAVs and the ground station, and the locations of both searching MAVs and ferrying MAVs are estimated to compute the distances between the MAVs and destination. The MAV that is closest to the destination is selected greedy to forward packet. If a MAV cannot find the next hop MAV using the greedy strategy, the packets will be stored and re-forwarded once again in the next time slot. The experiment results show that the proposed DTN_est algorithm outperforms the typical DTN_geo algorithm in terms of packet delivery ratio and average routing hops.

• Molecules and Cells
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• v.38 no.9
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• pp.759-764
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• 2015

Tripartite motif protein 25 (TRIM25), mediates K63-linked polyubiquitination of Retinoic acid inducible gene I (RIG-I) that is crucial for downstream antiviral interferon signaling. Here, we demonstrate that TRIM25 is required for melanoma differentiation-associated gene 5 (MDA5) and MAVS mediated activation of NF-${\kappa}B$ and interferon production. TRIM25 is required for the full activation of NF-${\kappa}B$ at the downstream of MAVS, while it is not involved in IRF3 nuclear translocation. Mechanical studies showed that TRIM25 is involved in TRAF6-mediated NF-${\kappa}B$ activation. These collectively indicate that TRIM25 plays an additional role in RIG-I/MDA5 signaling other than RIG-I ubiquitination via activation of NF-${\kappa}B$.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.2
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• pp.212-217
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• 2014

Micro Aerial Vehicles (MAVs) are useful devices to assess new features that may be utilized in a full size aircraft to enhance performance or to increase endurance. In this article, sources for energy saving in the micro air vehicles are initially addressed. Then, by specifying the important parameters on energy consumption of an aircraft, a feasibility study is conducted to assess the benefit of using solar cells to increase flight endurance. Next, a new solar cell has been designed and optimized for MAVs. This cell consists of a multiple quantum wells for which the quantum factor and the absorption coefficient are calculated by solving the Shrodinger equation using MATLAB software. Then, the manner and influence of MAVs parameters using the solar cells are examined to suggest optimal planform for different purposes. In order to increase flight endurance, it is noted that by using appropriate planform and the optimized solar cells, flight endurance can be increased by more than 30 percent.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.600-606
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• 2023

Dengue virus (DENV) is a widespread arbovirus. To efficiently establish infection, DENV evolves multiple strategies to hijack the host innate immune response. Herein, we examined the inhibitory effects of DENV serotype 2 (DENV2) nonstructural proteins on RIG-I-directed antiviral immune response. We found that DENV2 NS2A, NS2B, NS4A, and NS4B significantly inhibited RIG-I-mediated IFN-β promoter activation. The roles of NS2B in RIG-I-directed antiviral immune response are unknown. Our study further showed that NS2B could dose-dependently suppress RIG-I/MAVS-induced activation of IFN-β promoter. Consistently, NS2B significantly decreased RIG-I- and MAVS-induced transcription of IFNB1, ISG15, and ISG56. Mechanistically, NS2B was found to interact with MAVS and IKKε to impair RIG-I-directed antiviral response. Our findings demonstrated a previously uncharacterized function of NS2B in RIG-I-mediated antiviral response, making it a promising drug target for anti-DENV treatments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.2
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• pp.121-127
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• 2011

This paper presents an autonomous formation flight algorithm for micro aerial vehicles (MAVs) and its flight test results. Since MAVs have severe limits on the payload and flight time, formation of MAVs can help alleviate the mission load of each MAV by sharing the tasks or coverage areas. The proposed formation guidance law is designed using nonlinear dynamic inversion method based on 'Leader-Follower' formation geometric relationship. The sensing of other vehicles in a formation is achieved by sharing the vehicles' states using a high-speed radio data link. the designed formation law was simulated with flight data of MAV to verify its robustness against sensor noises. A series of test flights were performed to validate the proposed formation guidance law. The test result shows that the proposed formation flight algorithm with inter-communication is feasible and yields satisfactory results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.826-831
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• 2004

Recently, studies have been carried out to develop unmanned Micro Air Vehicles(MAVs) that can search and monitor inside buildings during urban warfare or rescue operations in hazardous environments. However, existing fixed-wing and rotary-wing MAVs cannot travel at extremely low or high speeds, hover in place, or change directions instantly. This has lead researches to search for other flight methods that could overcome those drawbacks. Insect flight principles and its applications to MAVs are being studied as an alternative flight method. To take flight, insects flap and rotate their wings. These wing motions allow for high maneuverability flight such as hovering, vertical take off and landing, and quick acceleration and deceleration. This paper proposes a method for designing a mechanism that reproduces hovering insect flight, the basis for all other forms of insect flight. The design of a mechanism that can reproduce the motion that causes maximum lift is proposed, the required specifications are calculated, and a method for reproducing hovering insect flight with a single motor is presented. Also, feasibility of the design was confirmed by simulation.

• Journal of Aerospace System Engineering
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• v.14 no.1
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• pp.68-73
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• 2020

This purpose of this paper was to review the development trend of the VTOL MAVs with a ducted propellant that can fly like the VTOL at intermediate and high speeds, hovering, landing, and lifting off vertically over urban areas, warships, bridges, and mountainous terrains. The MAV differs in flight characteristics from helicopters and fixed wings in many respects. In addition to enhancing thrust, the duct protects personnel from accidental contact with the spinning rotor. The purpose of the U.S. Army FCS and DARPA's OAV program is spurring development of a the VTOL ducted MAV. Today's MAVs are equipped with video/infrared cameras to hover-and-stare at enemies hidden behind forests and hills for approximately one hour surveillance and reconnaissance. Class-I is a VTOL ducted MAV developed in size and weight that individual soldiers can store in their backpacks. Class-II is the development of an organic VTOL ducted fan MAV with twice the operating time and a wider range of flight than Class-I. MAVs will need to develop to perch-and-stare technology for lengthy operation on the current hover-and-stare. The near future OAV's concept is to expand its mission capability and efficiency with a joint operation that automatically lifts-off, lands, refuels, and recharges on the vehicle's landing pad while the manned-unmanned ground vehicle is in operation. A ducted MAV needs the development of highly accurate relative position technology using low cost and small GPS for automatic lift-off and landing on the landing pad. There is also a need to develop a common command and control architecture that enables the cooperative operation of organisms between a VTOL ducted MAV and a manned-unmanned ground vehicle.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.10
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• pp.81-92
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• 1995

In this paper, we present a high-level synthesis system that generates area-efficient RT-level datapaths with multiport memories. The proposed scheduling algorithm assigns an operation to a specific control step such that maximal sharing of functional units can be achieved with minimal number of memory ports, while satisfying given constraints. We propose a measure of multiport memory cost, MAV (Multiple Access Variable) which is defined as a variable accessed at several control steps , and overall memory cost is reduced by equally distributing the MAVs throughout all the control steps. Experimental results show the effectiveness of the proposed algorithm. When compared with previous approaches for several benchmarks available from literature, the proposed algorithm generates the datapaths with less memory modules and interconnection structures by reflecting the memory cost in the scheduling process.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.2
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• pp.176-187
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• 2002

This paper focuses on the study of simulation and evolution of Micro Air Vehicles. Micro Air Vehicles or MAVs are small flying robots that are used for surveillance, search and rescue, and other missions. The simulated robots are designed based on realistic characteristics and the brains (controllers) of the robots are generated using genetic algorithms, i .e., simulated evolution. The objective for the experiments is to investigate the effects of robot team size and topology (simulation environment) on the evolution of simulated robots. The testing of team sizes deals with finding an ideal number of robots to be deployed for a given mission. The goal of the topology experiments is to see if there is an ideal topology (environment) to evolve the robots in order to increase their utility in most environments. We compare the results of the various experiments by evaluating the fitness values of the robots i .e., performance measure. In addition, evolved robot teams are tested in different situation in order to determine if the results can be generalized, and statistical analysis is performed to evaluate the evolved results.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.2
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• pp.152-161
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• 2013

This paper presents a control effectiveness analysis of the hawkmoth Manduca sexta. A multibody dynamic model of the insect that considers the time-varying inertia of two flapping wings is established, based on measurement data from the real hawkmoth. A six-degree-of-freedom (6-DOF) multibody flight dynamics simulation environment is used to analyze the effectiveness of the control variables defined in a wing kinematics function. The aerodynamics from complex wing flapping motions is estimated by a blade element approach, including translational and rotational force coefficients derived from relevant experimental studies. Control characteristics of flight dynamics with respect to the changes of three angular degrees of freedom (stroke positional, feathering, and deviation angle) of the wing kinematics are investigated. Results show that the symmetric (asymmetric) wing kinematics change of each wing only affects the longitudinal (lateral) flight forces and moments, which implies that the longitudinal and lateral flight controls are decoupled. However, there are coupling effects within each plane of motion. In the longitudinal plane, pitch and forward/backward motion controls are coupled; in the lateral plane, roll and side-translation motion controls are coupled.