The East China Sea (ECS) has experienced severe harmful algal blooms (HABs) that have deleterious ecological effects on marine organisms. Recent studies indicated that deploying of a second ...geostationary ocean color imager (GOCI-II) can significantly improve ocean monitoring. This study systematically assessed GOCI-II and its ability to detect HABs and distinguish between dinoflagellates and diatoms in the ECS. First, the remote-sensing reflectance (
R
rs
λ
,
λ
represents the wavelength) obtained from GOCI-II was compared to the local measurement data. Compared to the bands at 412 and 443 nm, the bands at 490, 510, and 620 nm exhibited excellent consistency, which is important for HAB detection. Second, four different methods were employed to extract bloom areas in the ECS: red tide index (RI), spectral shape (SS), red band line height ratio (LHR), and algal bloom ratio (
R
AB
). The SS (510) algorithm was the most applicable for detecting blooms from GOCI-II imagery. Finally, the classification capability of GOCI-II for dinoflagellates and diatoms was evaluated using three existing algorithms: the bloom index (BI), combined
Prorocentrumdonghaiens
index (PDI) and diatom index (DI), and the spectral slope (
R
_
s
l
o
p
e
). The BI algorithm yielded more satisfactory results than the other algorithms.
In this study, a sliding mode surface controller (SMC) designed for a quadcopter is experimentally tested. The SMC was combined with disturbance observers in six degrees of freedom of the quadcopter ...to effectively reject external disturbances. While respecting stability conditions all control parameters were automatically initialized and tuned using a simulation-based offline particle swarm optimization (PSO) algorithm, followed by onboard manual fine-tuning. To demonstrate its superiority, the SMC was compared with a PSO-optimized PID controller in terms of agility, stability, and the accurate tracking of hover, rectangular, and figure-eight pattern trajectories. To evaluate its robustness, the SMC controller was extensively tested in a small, enclosed, turbulent space while being subjected to a series of external disturbances, such as hanging payloads and lateral wind.
This work designed a disturbance-observer-based nonlinear sliding mode surface controller (SMC) and validated the controller using a simulated PX4-conducted quadcopter. To achieve this goal, this ...research (1) developed a dynamic mathematical model; (2) built a PX4-based simulated UAV following the model-based design process; (3) developed appropriate sliding mode control laws for each degree of freedom; (4) implemented disturbance observers on the proposed SMC controller to achieve finer disturbance rejection such as crosswind effect and other mutational disturbances; (5) optimized the SMC controller’s parameters based on particle swarm optimization (PSO) method; and (6) evaluated and compared the quadcopter’s tracking performance under a range of noise and disturbances. Comparisons of PID control strategies against the SMC were documented under the same conditions. Consequently, the SMC controller with disturbance observer facilitates accurate and fast UAV adaptation in uncertain dynamic environments.
This work presents and experimentally tests the framework used by our context-aware, distributed team of small Unmanned Aerial Systems (SUAS) capable of operating in real time, in an autonomous ...fashion, and under constrained communications. Our framework relies on a three-layered approach: (1) an operational layer, where fast temporal and narrow spatial decisions are made; (2) a tactical layer, where temporal and spatial decisions are made for a team of agents; and (3) a strategical layer, where slow temporal and wide spatial decisions are made for the team of agents. These three layers are coordinated by an ad hoc, software-defined communications network, which ensures sparse but timely delivery of messages amongst groups and teams of agents at each layer, even under constrained communications. Experimental results are presented for a team of 10 small unmanned aerial systems tasked with searching for and monitoring a person in an open area. At the operational layer, our use case presents an agent autonomously performing searching, detection, localization, classification, identification, tracking, and following of the person, while avoiding malicious collisions. At the tactical layer, our experimental use case presents the cooperative interaction of a group of multiple agents that enables the monitoring of the targeted person over wider spatial and temporal regions. At the strategic layer, our use case involves the detection of complex behaviors, i.e., the person being followed enters a car and runs away, or the person being followed exits the car and runs away, which require strategic responses to successfully accomplish the mission.
This dissertation presents a comprehensive approach to addressing the challenges associated with the control and navigation of Unmanned Aerial Vehicles (UAVs), specifically focusing on robustness ...under GPS-denied, turbulent, and dark indoor conditions with various disturbances. Initial efforts involved designing and theoretically validating Sliding Mode Controllers (SMC) with Disturbance Observers using MATLAB/SIMULINK, optimized using offline Particle Swarm Optimization (PSO). In order to evaluate their performance, a lightweight simulator was developed to simulate both quadcopter and hexacopter configurations under the PX4 architecture. This simulator served to validate and compare the optimized SMC against PSO-optimized PID controllers. The results of these comparisons demonstrated the superior adaptability of the SMC, especially in environments characterized by significant sensor noise and disturbances. Subsequent practical indoor tests were conducted with real quadcopters, which provided additional verification of the robustness and reliability of the enhanced control theory with the actual UAVs under dynamic disturbances. To further evaluate the compatibility and adaptability of the SMC, this dissertation establishes a framework for interfacing with high-performance STMH7 chips, serving as the UAV microcontroller unit (MCU). This framework facilitates the connection of various sensors and provides guidance for constructing different quadcopter frames. Moreover, it enables the comparison of different flight controllers on distinct air-frames. Concurrently, the optimized SMC allows for remote dynamic parameter tuning during flight. In pursuit of improved localization capacity, the dissertation also explores the integration of an Intel Realsense D435i camera with an Inertial Measurement Unit (IMU) for Visual-Inertial Odometry (VIO) fusion within the Robot Operating System (ROS) environment. This integration employs an onboard companion computer for real-time VIO estimation and flight command. The effectiveness of the VIO algorithm is verified through both simulations and real-world experiments, highlighting its ability to enhance UAV localization and navigation. Additionally, a visual inertial odometry method for UAV Simultaneous Localization and Mapping (vSLAM) is tested and validated in both simulated and real drone environments. Furthermore, the dissertation introduces an innovative hybrid filtered multi-directional radar inertial odometry solution denoted as Hybrid-MRIO. This Error State Extended Kalman Filter (ES-EKF) based Radar Inertial Odometry (RIO) approach is implemented within the open-source PX4 autopilot system, enhancing UAV navigation accuracy and performance, and serves as a robust navigation alternative, particularly in challenging environments where traditional navigation systems prove ineffective, such as dark or smoky conditions. This solution integrates data from multiple software synchronized high-resolution Frequency-Modulated Continuous-Wave (FMCW) mmWave radars with an IMU. A subsequent 4D (x, y, z, doppler) mmWave radar SLAM (rSLAM) system has been developed, including three modules: front-end, loop detection module, and back-end. In the front-end, radar ego-velocity is utilized for states estimation and dynamic object removal, and a point cloud registration-based approach known as APDGICP (Adaptive Probability Distribution-GICP) is employed for keyframe detection. The loop detection module utilizes the intensity scan context to identify potential loop closure candidates. In the back-end, a pose graph is constructed, integrating RIO estimated odometry and identified loop closures for better localization.To develop fully-autonomous UAVs with their decision making modules, this dissertation details the development of a custom AI-powered fully-autonomous quadcopter equipped with companion computers and stereo IR cameras. Additionally, this dissertation discusses a swarm of small Unmanned Aerial Systems (SUAS) interconnected through a software-defined communications network. These drones demonstrated their capacity to independently/collaboratively execute a wide range of tasks, including target search, detection, identification, classification, tracking, and following, both in simulated and real-world scenarios. The system exhibits advanced collision avoidance capabilities and the ability to strategically respond to dynamic scenarios, such as changes in target behavior, highlighting its effectiveness in managing dynamic and challenging situations without the need for continuous human intervention.
Jasmonic acid（JA） and related metabolites play a key role in plant defense and growth. JA carboxyl methyltransferase（JMT） may be involved in plant defense and development by methylating JA to methyl ...jasmonate（Me JA） and thus influencing the concentrations of JA and related metabolites. However, no JMT gene has been well characterized in monocotyledon defense and development at the molecular level. After we cloned a rice JMT gene,Os JMT1, whose encoding protein was localized in the cytosol, we found that the recombinant Os JMT1 protein catalyzed JA to Me JA. Os JMT1 is up-regulated in response to infestation with the brown planthopper（BPH; Nilaparvata lugens）. Plants in which Os JMT1 had been overexpressed（oeJMT plants） showed reduced height and yield. These oe-JMT plants also exhibited increased Me JA levels but reduced levels of herbivore-induced JA and jasmonoyl-isoleucine（JAIle）. The oe-JMT plants were more attractive to BPH female adults but showed increased resistance to BPH nymphs,probably owing to the different responses of BPH female adults and nymphs to the changes in levels of H_2O_2 and Me JA in oe-JMT plants. These results indicate that Os JMT1,by altering levels of JA and related metabolites, plays a role in regulating plant development and herbivore-induced defense responses in rice.
Software systems are a typical kind of man-made complex systems. Understanding their evolutions can lead to better software engineering practices. In this paper, the authors use complex network ...theory as a tool to analyze the evolution of object-oriented （OO） software from a multi-granularity perspective. First, a multi-granularity software networks model is proposed to represent the topological structures of a multi-version software system from three levels of granularity. Then, some parameters widely used in complex network theory are applied to characterize the software networks. By tracing the parameters＇ values in consecutive software systems, we have a better understanding about software evolution. A case study is conducted on an open source OO project, Azureus, as an example to illustrate our approach, and some underlying evolution characteristics are uncovered. These results provide a different dimension to our understanding of software evolutions and also are very useful for the design and development of OO software systems.
This work presents and experimentally test the framework used by our context-aware, distributed team of small Unmanned Aerial Systems (SUAS) capable of operating in real-time, in an autonomous ...fashion, and under constrained communications. Our framework relies on three layered approach: (1) Operational layer, where fast temporal and narrow spatial decisions are made; (2) Tactical Layer, where temporal and spatial decisions are made for a team of agents; and (3) Strategical Layer, where slow temporal and wide spatial decisions are made for the team of agents. These three layers are coordinated by an ad-hoc, software-defined communications network, which ensures sparse, but timely delivery of messages amongst groups and teams of agents at each layer even under constrained communications. Experimental results are presented for a team of 10 small unmanned aerial systems tasked with searching and monitoring a person in an open area. At the operational layer, our use case presents an agent autonomously performing searching, detection, localization, classification, identification, tracking, and following of the person, while avoiding malicious collisions. At the tactical layer, our experimental use case presents the cooperative interaction of a group of multiple agents that enable the monitoring of the targeted person over a wider spatial and temporal regions. At the strategic layer, our use case involves the detection of complex behaviors-i.e. the person being followed enters a car and runs away, or the person being followed exits the car and runs away-that requires strategic responses to successfully accomplish the mission.
To study the accuracy of different formulas forecasting intracellular lens (IOL) power after excimer laser keratorefractive operation.
One hundred and twenty eyes (60 cases) underwent LASIK surgery. ...Before and after the surgery, the IOL powers were calculated to correct the myopia to emmetropia by experiential SRK II formula, theoretical SRK/T formula and Binkhoist II formula respectively. Then we calculated the IOL power equal to original lens power by F, and analyzed the results before and after surgery by SPSS statistical software.
1. The IOL powers were not obviously different by different formulas between pre-operative and post-operative results in low myopia (P > 0.05). In middle and high myopia there were obvious differences (P < 0.01), the postoperative results were smaller than the preoperative ones. 2. The differences of equal IOL power by different formulas were highly related to the practical corrective refractive values of the surgery. Regression formula: The difference of equal IOL power = a + b
Distributions of the rare-earth elements (REE) in omphacite and garnet and REE behaviors during metamorphic processes were discussed. The REE concentrations of garnet and omphacite in six eclogite ...samples from the Dabie Mountain, central China, were measured by inductively coupled plasma-mass spectrometry (ICP-MS). The correlation of δEu ratios between garnet and omphacite indicated that chemical equilibrium of REE distribution between garnet and omphacite could be achieved during ultra-high pressure (UHP) metamorphism. Most of the partition coefficients (K ^sub d^=C^sub i^ ^sup Omp^/C^sub i^ ^sup Grt^) of light rare-earth elements (LREE) are higher than 1. However the partition coefficients of heavy rare-earth elements (HREE) are lower than 1. This indicated that the LREE inclined to occupy site M2 in omphacite, but the HREEs tended to occupy eightfold coordinated site in garnet during the eclogite formation. The REE geochemistry of the eclogites indicated that LREE could be partially lost during the prograde metamorphic process of protolith, but be introduced into the rocks during the symplectite formation. LREE are more active than HREE during the UHP metamorphism. The results are favorable to highlighting the REE behavior and evolution of UHP metamorphic rocks.PUBLICATION ABSTRACT
