ASSESSMENT OF ELECTRO-OPTICAL IMAGING TECHNOLOGY FOR UNMANNED AERIAL SYSTEM NAVIGATION IN A GPS-DENIED ENVIRONMENT

Navigation systems of unmanned aircraft systems (UAS) are heavily dependent on the availability of Global Positioning Systems (GPS) or other Global Navigation Satellite Systems (GNSS). Although inertial navigation systems (INS) can provide position and velocity of an aircraft based on acceleration measurements, the information degrades over time and reduces the capability of the system. In a GPS-denied environment, a UAS must utilize alternative sensor sources for navigating. This thesis presents preliminary evaluation results on the usage of onboard down-looking electro-optical sensors and image matching techniques to assist in GPS-free navigation of aerial platforms. Following the presentation of the fundamental mathematics behind the proposed concept, the thesis analyzes the key results from three flight campaign experiments that use different sets of sensors to collect data. Each of the flight experiments explores different sensor setups, assesses a variety of image processing methods, looks at different terrain environments, and reveals limitations related to the proposed approach. In addition, an attempt to incorporate navigational aid solutions into a navigation system using a Kalman filter is demonstrated. The thesis concludes with recommendations for future research on developing an integrated navigation system that relies on inertial measurement unit data complemented by the positional fixes from the image-matching technique.Outstanding ThesisCivilian, DSO National Laboratories, SingaporeApproved for public release. Distribution is unlimited

The Medium Matters: Effects on What Consumers Talk about Regarding Movie Trailers

Entertainment consumers are known to consult others’ opinions to make consumption decisions via social media. However, little research has investigated whether various configurations of communication media design features affect what consumers talk about regarding movie trailers. To address the research question, we integrate past research on psychological drivers of interpersonal communication and computer-mediated communication to propose that different commentary presentation of social media would affect the relative importance of communication motivations, which in turn shapes the specific messages communicated (i.e., valence, informational content, and emotional content). We propose two studies to test our research model and hypotheses. We hope to contribute to the literature by empirically investigating the creation of specific types of messages, elucidating the role of configuration of social media design features in shaping the messages communicated, and highlighting the impacts of interface design on achieving interpersonal communication goals

Adaptive Network Coding Scheme for TCP over Wireless Sensor Networks

The purpose of this paper is to develop a network coding scheme to enhance TCP performance in wireless sensor networks. It is well known that TCP performs poorly over wireless links which suffer from packet losses mainly due to the bad channel. To address this problem, it is useful to incorporate network coding into TCP, as network coding can offer significant benefits in terms of throughput, reliability, and robustness. However, the encoding and decoding operations of network coding techniques will bring an additional delay that has a negative effect on applications of wireless sensor networks. In this paper, we propose an adaptive network coding (ANC) scheme which contains two major aspects: the adjustment of the redundancy factor R and the adjustment of the coding window size CW. We dynamically adjust these two parameters depending on the measured packet loss rate, so that the proposed ANC can effectively mask packet losses and reduce the decoding delay of network coding. The performance of our scheme is evaluated by simulations using NS-2 simulator. Compared to other schemes, the ANC not only achieves a good throughput but also has the lowest average delay and the lowest maximum delay in all experimental environments

eHint: An Efficient Protocol for Uploading Small-Size IoT Data

IoT (Internet of Things) has attracted a lot of attention recently. IoT devices need to report their data or status to base stations at various frequencies. The IoT communications observed by a base station normally exhibit the following characteristics: (1) massively connected, (2) lightly loaded per packet, and (3) periodical or at least mostly predictable. The current design principals of communication networks, when applied to IoT scenarios, however, do not fit well to these requirements. When a large number of devices contend to send small packets, the signaling overhead is not cost-effective. To address this problem, our previous work [1] proposes the Hint protocol, which is slot-based and schedule- oriented for uploading IoT devices' data. In this work, we extend [1] to support data transmissions for multiple resource blocks. We assume that the uplink payloads from IoT devices are small, each taking very few slots (or resource blocks), but devices are massive. The main idea is to "encode" information in a tiny broadcast that allows each device to "decode" its transmission slots, thus significantly reducing transmission overheads and contention overheads. Our simulation results verify that the protocol can significantly increase channel utilization compared with traditional schemes

Multi-Slot Allocation Protocols for Massive IoT Devices with Small-Size Uploading Data

The emergence of Internet of Things applications introduces new challenges such as massive connectivity and small data transmission. In traditional data transmission protocols, an ID (i.e., IP address or MAC address) is usually included in a packet so that its receiver is able to know who sent the packet. However, this introduces the big head-small body problem for light payload. To address this problem, the Hint protocols have been proposed. The main idea is to 'encode' information in a tiny broadcast Hint message that allows devices to 'decode' their transmission slots. Thus, it can significantly reduce transmission and contention overheads. In this letter, we extend eHint to support multi-slot data transmissions. Several efficient protocols are proposed. Our simulation results validate that the protocols can significantly increase the number of successfully transmitted devices, channel utilization, and payload of transmitted devices compared with eHint

How to Reduce Unexpected eMBMS Session Disconnection: Design and Performance Analysis

In 3GPP eMBMS, sometimes sessions will be disconnected unexpectedly due to the miss of session keys. Although rekeying can prevent old users from getting multicast data, it also causes authorized users to miss subsequent data if they miss the key update messages. Thus, re-authentication is needed to obtain lost keys from KMM. We point out this problem in our previous work 1. In this paper, we further propose a new KeySet algorithm, which can pre-issue a number of keys to users when they join eMBMS. The advantage is that a user can still decode multicast data even if it misses some key updates tentatively. However, the cost is that allowing some old users to freely enjoying multicast for some time. In this paper, we quantify the tradeoff and derive the optimal case

Novel biodegradable sandwich-structured nanofibrous drug-eluting membranes for repair of infected wounds: an in vitro and in vivo study

Dave Wei-Chih Chen1,2, Jun-Yi Liao3, Shih-Jung Liu2, Err-Cheng Chan41Department of Orthopedic Surgery, Chang Gung Memorial Hospital, 2Department of Mechanical Engineering, 3Graduate Institute of Medical Mechatronics, 4School of Medical Technology, Chang Gung University, Kwei-San, Tao-Yuan, TaiwanBackground: The purpose of this study was to develop novel sandwich-structured nanofibrous membranes to provide sustained-release delivery of vancomycin, gentamicin, and lidocaine for repair of infected wounds.Methods: To prepare the biodegradable membranes, poly(D, L)-lactide-co-glycolide (PLGA), collagen, and various pharmaceuticals, including vancomycin, gentamicin, and lidocaine, were first dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol. They were electrospun into sandwich-structured membranes with PLGA/collagen as the surface layers and PLGA/drugs as the core. An elution method and a high-pressure liquid chromatography assay were used to characterize in vivo and in vitro drug release from the membranes. In addition, repair of infected wounds in rats was studied. Histological examination of epithelialization and granulation at the wound site was also performed.Results: The biodegradable nanofibrous membranes released large amounts of vancomycin and gentamicin (well above the minimum inhibition concentration) and lidocaine in vivo for more than 3 weeks. A bacterial inhibition test was carried out to determine the relative activity of the antibiotics released. The bioactivity ranged from 40% to 100%. The nanofibrous membranes were functionally active in treating infected wounds, and were very effective as accelerators in early-stage wound healing.Conclusion: Using the electrospinning technique, we will be able to manufacture biodegradable, biomimetic, nanofibrous, extracellular membranes for long-term delivery of various drugs.Keywords: nanofibrous, sandwich-structured, drug-eluting membranes, electrospinning, release characteristics, repair, wound infectio

Endothelial-derived APT1-mediated macrophage-endothelial cell interactions participate in the development of atherosclerosis by regulating the Ras/MAPK signaling pathway

Acyl-protein thioesterase 1 (APT1) can affect H-Ras localization and function by promoting its depalmitoylation. However, relatively little attention has been paid to the effects of APT1 on H-Ras in the cardiovascular system. In this study, we revealed its roles in atherosclerosis development using oxidative low-density lipoprotein (ox-LDL)-induced endothelial dysfunction models and a Western diet-induced ApoE−/− mouse model. The results showed that APT1 expression was up-regulated, while that of miR-138-5p (miR-138) was down-regulated (p < 0.05) in this model. In the meantime, APT1 and H-Ras were translocated from the cytoplasm to the plasma membrane. Bioinformatic analysis and double fluorescence identified miR-138 as the upstream regulator of APT1. APT1 knockdown regulated H-Ras localization and expression, which subsequently affected the MAPK signaling pathway and the expression of its downstream factors. Further research indicated that human umbilical vein endothelial cells (HUVECs)-derived biogenic nanoparticles (BiNPs), hBPs secretion, and RNA expression of hBP-loaded APT1 were increased (p < 0.05) in the ox-LDL induced endothelial dysfunction model. Meanwhile, the HUVECs-derived APT1 could further affect macrophage function through hBP transportation. Altogether, this study demonstrated that the miR-138-APT1 axis may be partially responsible for atherosclerosis development by regulating the H-Ras-MAPK signaling pathway and hBP transportation. The results also shed novel insight on the underlying mechanisms of, and identify potential diagnostic and therapeutic targets for, atherosclerotic cardiovascular diseases in the future

Estimating Probable Maximum Precipitation and Probable Maximum Flood by Considering the Combined Effect of Typhoon and Monsoon Weather System under Climate Change

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive