Design and Control of the "TransBoat": A Transformable Unmanned Surface Vehicle for Overwater Construction

This paper presents the TransBoat, a novel omnidirectional unmanned surface vehicle (USV) with a magnetbased docking system for overwater construction with wave disturbances. This is the first such USV that can build overwater structures by transporting modules. The TransBoat incorporates two features designed to reject wave disturbances. First, the TransBoat's expandable body structure can actively transform from a mono-hull into a multi-hull for stabilization in turbulent environments by extending its four outrigger hulls. Second, a real-time nonlinear model predictive control (NMPC) scheme is proposed for all shapes of the TransBoat to enhance its maneuverability and resist disturbance to its movement, based on a nonlinear dynamic model. An experimental approach is proposed to identify the parameters of the dynamic model, and a subsequent trajectory tracking test validates the dynamics, NMPC controller and system mobility. Further, docking experiments identify improved performance in the expanded form of the TransBoat compared with the contracted form, including an increased success rate (of ~ 10%) and reduced docking time (of ~ 40 s on average). Finally, a bridge construction test verifies our system design and the NMPC control method

NuScenes-QA: A Multi-modal Visual Question Answering Benchmark for Autonomous Driving Scenario

We introduce a novel visual question answering (VQA) task in the context of autonomous driving, aiming to answer natural language questions based on street-view clues. Compared to traditional VQA tasks, VQA in autonomous driving scenario presents more challenges. Firstly, the raw visual data are multi-modal, including images and point clouds captured by camera and LiDAR, respectively. Secondly, the data are multi-frame due to the continuous, real-time acquisition. Thirdly, the outdoor scenes exhibit both moving foreground and static background. Existing VQA benchmarks fail to adequately address these complexities. To bridge this gap, we propose NuScenes-QA, the first benchmark for VQA in the autonomous driving scenario, encompassing 34K visual scenes and 460K question-answer pairs. Specifically, we leverage existing 3D detection annotations to generate scene graphs and design question templates manually. Subsequently, the question-answer pairs are generated programmatically based on these templates. Comprehensive statistics prove that our NuScenes-QA is a balanced large-scale benchmark with diverse question formats. Built upon it, we develop a series of baselines that employ advanced 3D detection and VQA techniques. Our extensive experiments highlight the challenges posed by this new task. Codes and dataset are available at https://github.com/qiantianwen/NuScenes-QA

In-Vitro Study on the Antibacterial and Antioxidant Activity of Four Commercial Essential Oils and In-Situ Evaluation of Their Effect on Quality Deterioration of Pacific White Shrimp (Litopenaeus vannamei) during Cold Storage

The antioxidant and antibacterial properties of four essential oils (oregano essential oil (OEO), tea tree essential oil (TTEO), wild orange essential oil (WOEO), and clove leaf essential oil (CLEO)) were determined. The in-vitro experiment indicated that CLEO had the highest total phenolic content and DPPH scavenging activity, and OEO displayed the highest antibacterial effect, so they were applied to maintain the quality of shrimp for further study. In-situ study, the total viable counts of shrimp were inhibited from 9.05 log CFU/g to 8.18 and 8.34 log CFU/g by 2% of OEO and CLEO treated alone on 10 d. The melanosis ratio was also retarded from 38.16% to 28.98% and 26.35% by the two essential oils. The inhibitory effects of OEO and CLEO on the increase of PPO activity, weight loss, and TCA-soluble peptides, and the decreasing tendency of whiteness, the contents of myofibrillar and sarcoplasmic proteins were also founded. The samples treated with 1% OEO + 1% CLEO had better quality than those treated alone. Therefore, the combination of OEO and CLEO had a synergistic effect, which displayed the highest efficiency to prevent the melanosis, bacterial growth, and protein hydrolysis of shrimp.Peer reviewe

2-(4-Fluoro­anilino)-3-(2-hydroxy­ethyl)quinazolin-4(3H)-one

The mol­ecular and crystal structures of the title compound, C16H14FN3O2, are stabilized by intra­molecular N—H⋯O and inter­molecular O—H⋯O hydrogen bonds. The existence of non-classical intra­molecular C—H⋯N hydrogen bonds provides a dihedral angle between the fluoro-substituted benzene and pyrimidinone rings of 7.9 (1)°

Simultaneous thermoosmotic and thermoelectric responses in nanoconfined electrolyte solutions: Effects of nanopore structures and membrane properties

Hypothesis: Nanofluidic systems provide an emerging and efficient platform for thermoelectric conversion and fluid pumping with low-grade heat energy. As a basis of their performance enhancement, the effects of the structures and properties of the nanofluidic systems on the thermoelectric response (TER) and the thermoosmotic response (TOR) are yet to be explored. Methods: The simultaneous TER and TOR of electrolyte solutions in nanofluidic membrane pores on which an axial temperature gradient is exerted are investigated numerically and semi-analytically. A semi-analytical model is developed with the consideration of finite membrane thermal conductivity and the reservoir/entrance effect. Findings: The increase in the access resistance due to the nanopore-reservoir interfaces accounts for the decrease of short circuit current at the low concentration regime. The decrease in the thermal conductivity ratio can enhance the TER and TOR. The maximum power density occurring at the nanopore radius twice the Debye length ranges from several to dozens of mW K$^{-2}$ m$^{-2}$ and is an order of magnitude higher than typical thermo-supercapacitors. The surface charge polarity can heavily affect the sign and magnitude of the short-circuit current, the Seebeck coefficient, and the open-circuit thermoosmotic coefficient, but has less effect on the short-circuit thermoosmotic coefficient. Furthermore, the membrane thickness makes different impacts on TER and TOR for zero and finite membrane thermal conductivity.Comment: 38 pages, 10 figure

Ethyl 2-[(Z)-2-benzyl­hydrazin-1-yl­idene]-2-bromo­acetate

In the title compound, C11H13BrN2O2, the dihedral angle between the phenyl ring and the almost planar (r.m.s. deviation = 0.011 Å) C—C(Br)=N—N(H)— fragment is 74.94 (16)°. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, which generate C(6) chains propagating in [010]. Weak aromatic π–π stacking [centroid–centroid separation = 3.784 (3) Å] may also help to consolidate the packing

Carbon-Dot-Sensitized, Nitrogen-Doped TiO2in Mesoporous Silica for Water Decontamination through Nonhydrophobic Enrichment-Degradation Mode

Mesoporous silica synthesized from the co-condensation of tetraethoxysilane and silylated carbon dot containing amide group has been adopted as the carrier for the in-situ growth of TiO2 through an impregnation-hydrothermal crystallization process. Benefitted from the initial complexing between the titania precursor and carbon dot, highly dispersed anatase TiO2 nanoparticles can be formed inside the mesoporous channel. The hybrid material possesses ordered hexagonal mesostructure with a p6mm symmetry, high specific surface area (446.27 m2g-1), large pore volume (0.57 cm3g-1), uniform pore size (5.11 nm) and a wide absorption band between 300-550 nm. TiO2 nanocrystals are anchored to carbon dot through bonds of Ti-O-N and Ti-O-C as revealed by X-ray photoelectron spectroscopy. Moreover, the nitrogen doping of TiO2 is also verified by the formation of Ti-N bond. This composite shows excellent adsorption capability to organic 2, 4-dichlorophenol and acid orange 7 with electron-deficient aromatic ring through the electron donor-acceptor interaction between carbon dot and organics instead of hydrophobic effect as analyzed by the contact angle analysis, which can be photocatalytically recycled through visible light irradiation after the adsorption. The narrowed bandgap by nitrogen doping and the photosensitization effect of carbon dot are revealed to be co-responsible for the visible-light activity of TiO2. The adsorption capacity does not suffer obvious loss after being recycled 3 times