KEYWORDS dynamic surface control (DSC), explosion of complexity, extended state observer (ESO), quadrotor unmanned aerial vehicle (UAV), unmeasurable velocity statesRecently, the control of a quadrotor unmanned aerial vehicle (UAV) has received considerable attention from the research community due to its significant characteristics in rapid maneuverability, precise hovering, and low-cost manufacturability with reduced mechanical complexity, thereby providing a well-suited mission platform for a variety of applications from military and civilian scenarios, including small-area monitoring, surveillance, detection in restricted terrains, and reconnaissance and mapping after disasters. [1][2][3] However, how to develop an effective robust flight controller that performs well in practice while ensuring asymptotic stability in theory is still a significant challenge because of the following essential reasons. 4 (i) The quadrotor UAV only 2700 Damping matrices = diag(k x ,k y ,k z ) = diag(0.01, 0.01, 0.01) Nms 2 = diag(k ,k ,k ) = diag(0.012, 0.012, 0.012) Nms 2 J Inertial matrix J = diag(J 1 ,J 2 ,J 3 ) = diag(0.016, 0.016, 0.016) kgm 2 l Distance from each rotor 0.4 m to the center of mass c Force-to-moment factor 0.05

The sun is the most sustainable light source available on our planet, therefore the direct use of sunlight for photochemistry is extremely appealing. Demonstrated here, for the first time, is that a diverse set of photon‐driven transformations can be efficiently powered by solar irradiation with the use of solvent‐resistant and cheap luminescent solar concentrator based photomicroreactors. Blue, green, and red reactors can accommodate both homogeneous and multiphase reaction conditions, including photochemical oxidations, photocatalytic trifluoromethylation chemistry, and metallaphotoredox transformations, thus spanning applications over the entire visible‐light spectrum. To further illustrate the efficacy of these novel solar reactors, medicinally relevant molecules, such as ascaridole and an intermediate of artemisinin, were prepared as well.

The experimental data of viscosity and density for six binary mixtures of water (methanol or ethanol) with an ionic liquid, 1-butyl-3-methylimidazolium dimethylphosphate ([BMIM][DMP]) or 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM][DMP]), were measured in the temperature range of (293.15 to 333.15) K at atmospheric pressure using a viscometer and densimeter. The solution behavior of the mixtures is discussed in terms of the variation of the excess viscosity and excess volume with temperatures and compositions. It is found that both excess volume and viscosity of the mixtures studied show a negative deviation from the ideal solution behavior, and the viscosity of the mixtures decreases drastically with the increase of temperatures and mole fractions of solvents. The excess volume of the binary mixtures is quite low, in the range of (1.0 to 1.9) cm 3 3 mol À1 ; moreover, it shows a monotonic decrease with increasing temperature for the aqueous solution of ILs and a reverse trend for the IL solutions of methanol or ethanol at any concentrations. ' INTRODUCTIONIonic liquids (ILs), as a hybrid of neutral and ionic entities, show some unique properties, like negligible volatility, good conductivity and stability, and high solvating capacity for polar and nonpolar compounds, and are deemed as a potential greener solvent for many reactions and separation processes. For example, ILs might be applicable in the extractive desulfurization of fuel oils 1,2 and in extractive distillation of some mixtures with close boiling points or azeotropes 3,4 depending on the task and specific constituents of ILs. From the application point of view, it is necessary to know the physical and thermodynamic properties of ILs and their mixtures with other solvents, for example, density and viscosity, for the process design. From the academic point of view, the physical and thermodynamic data are also crucial in understanding the structureÀproperty relationship of ILs and the interaction between different ILs and solvents, in developing thermodynamic models, 5 and accordingly guiding the design of a task-specific ILs for different purposes.By far, many experimental data of density and viscosity of pure ILs have been reported and documented in some recent reviews; 6,7 however, the same property data for the IL-containing mixtures are quite scarce in comparison with the huge amount of IL species and possible combination approaches with different solvents. In our group, a series of vaporÀliquid equilibrium data have been measured for waterÀmethanolÀethanol systems containing an imidazolium-based ILs with a dialkylphosphate anion, for example, [MMIM][DMP], [EMIM][DEP], [BMIM][DBP], and [EEIM] [DEP], 8À10 aimed to find an appropriate entrainer for the efficient separation of ethanolÀwater solution. It is found that some of these ILs have a profound salting-out effect and can even break the azeotropic phenomena of the ethanolÀwater mixture at a specified IL-content and facilitate the distillation separation. To our understanding, these halog...

In order to reduce the computational complexity, and improve the pitch/roll estimation accuracy of the low-cost attitude heading reference system (AHRS) under conditions of magnetic-distortion, a novel linear Kalman filter, suitable for nonlinear attitude estimation, is proposed in this paper. The new algorithm is the combination of two-step geometrically-intuitive correction (TGIC) and the Kalman filter. In the proposed algorithm, the sequential two-step geometrically-intuitive correction scheme is used to make the current estimation of pitch/roll immune to magnetic distortion. Meanwhile, the TGIC produces a computed quaternion input for the Kalman filter, which avoids the linearization error of measurement equations and reduces the computational complexity. Several experiments have been carried out to validate the performance of the filter design. The results demonstrate that the mean time consumption and the root mean square error (RMSE) of pitch/roll estimation under magnetic disturbances are reduced by 45.9% and 33.8%, respectively, when compared with a standard filter. In addition, the proposed filter is applicable for attitude estimation under various dynamic conditions.

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