Dragonflies show impressive flight performance due to their unique tandem flapping wing configuration. While previous studies focused on forewing-hindwing interference in dragonfly-like wings, few have explored the role of asymmetric pitching angle wings. This paper compares aerodynamic wings with symmetric hummingbird-like both arranged tandem. Using a three-dimensional numerical model, we analyzed configurations single/tandem advance ratios (J) from 0 0.45, and phase differences (ϕ) 0°...

According to the mechanism analysis of drilling fluid loss in formation with low pressure-bearing capacity, three basic theories, including stress cage, plugged zone, and strength ring for wellbore strengthening, were summarized corresponding models established. The application conditions theories their requirements on material properties determined based models. Fracture propagation, filtration effect depleted pressure are major factors that lead capacity. cage theory strengthens by...

Real-time and drift-free state estimation is essential for the flight control of Micro Aerial Vehicles (MAVs). Due to vibration caused by particular flapping motion stringent constraints scale, weight, power, divergence actually becomes an open challenge wing platforms’ longterm stable flight. Unlike conventional MAVs, direct adoption mature strategies, such as inertial or vision-based methods, has difficulty obtaining satisfactory sensing performance on platforms. Inertial sensors offer...

Tight sandstone has a complex pore-throat structure and usually multiple immiscible displacement paths. Capillary number may control affect this process, but its mechanism is still unclear. Therefore, work aims to study the process of generalized capillary on tight sandstone. Through nuclear magnetic resonance (NMR) online experiments, real-time monitoring changes in remaining oil different-radius pores was performed under different numbers. Combined with microscopic experimental results...

Micro tandem bi-copters are capable of passing through narrow gaps owing to their particular slender shape. However, the introduction tilting servo motors leads a non-minimum phase roll dynamics, which affects flight stability when exploring environments with unpredictable disturbances. In this letter, we propose and design re-configurable aerial platform consisting two modular an undocking mechanism. combined configuration, crossover docking approach is employed compensate for poor in...

Flapping wing rotorcrafts (FWRs) combine both the motion characteristics of flapping and rotary wings, exhibiting high aerodynamic efficiency at low Reynolds numbers. In this paper, ceiling effect FWRs has been studied through numerical experimental methods to further investigate performance operating under a explore feasibility enhancing flight via ceiling-effect-based perching locomotion. Based on momentum theory blade element methods, theoretical model is first established predict...

Abstract To overcome the time delay in tele-robot system, a new 3D virtual environment modeling technology is proposed this paper. The interactions between slave robot and can be attained advance master side, therefore an accurate operation of space realized effect would minimized. Firstly, interaction scenario modeled as point cloud data image, target objects are recognized from image reconstructed by using Random Sample And Consensus (RANSAC) algorithm. Secondly, effective method to modify...

Compared with traditional flapping motion, the wing rotor (FWR) allows rotating freedom by installing two wings asymmetrically, which introduces rotary motion characteristics and enables FWR to have higher lift aerodynamic efficiency at low Reynolds number. However, most of proposed FWRs contain linkage mechanical transmission structures, fixed degrees prohibit from achieving variable trajectories, limiting further optimization controller design FWRs. In order fundamentally address above...

Due to the low penetration rate and random routes of floating cars, traffic state derived by car system could not cover all links road network, which has a great impact on performance dynamic management information applications. In this paper, link float passing through is obtained system. For without car, tensor form that can encode spatial temporal correlation simultaneously introduced modeling for first time. Then, cars completed completion method well mines multi-mode correlations model....

A mathematical model of Herschel−Bulkely (H-B) drilling fluid flow into a deformable fracture has been established in this work. The finite difference and element methods were applied for solving model. Influence operating parameters, characteristics, deformation, rheological properties, mud solids deposition fractures on the loss behaviors have investigated by numerical simulation based It found that rate total volume may aggravate with increasing differential pressure time. Fracture...

Micromanipulation In article number 2105414, Xue Bai, Lin Feng, and co-workers develop a magnetically actuated cell-robot system for micromanipulation. The robots exhibit high position control accuracy generate flow field that can be used to transport microspheres cells using an external rotating magnetic field. cell also form chain-like swarms large object.

Flapping Wing Rotorcraft (FWR) combines flapping and rotating wing motion in one element. Such a hybrid design integrates the high-efficiency characteristics of high-lift feature under low Reynolds number, providing broader range simultaneous lift power efficiency optimization. Nevertheless, flight performance current FWRs is limited by their complex transmission mechanisms. mechanical constraints not only induce coupled kinematics but also render tedious assembly work fabrication...

Optoelectronic tweezers (OET) system is a novel platform, by changing the projection pattern it can achieve real-time precise control of micro-objects. Due to its outstanding biocompatibility cells and other biological materials, such as no damage, less heat generation, contact characteristics, has attracted wide attention in field micro-nano robots micro-operation. Here we present low power, high precision operation method which large operating range. Firstly, properties dielectrophoresis...

This paper aimed to research the effects of inertial mass coefficient on knotless netting models used in tuna purse seine. Knotless nettings were modeled and simulated using mathematical mechanical models. In simulation, marine environment was imitated computer. The results demonstrated that a key factor affect stability model, especially sinking process, model presented more stable quicker convergent as increased. During fishing operation at sea, instability seine with nettings, area...

The purpose of shaft power matching contra-rotating axial flow fans (CRAFF) is to ensure the best utilization motors at their rated while not overload them operation.Usually it requires a lot time and effort due lack theoretical guidance and, thus, becomes major problem for application CRAFF. Through analyzing velocity triangle, authors have found nondimensional parameter k, defined as tangential ratio two relative outflow angles impellers, be critical successful aerodynamic design. then...

Test flight results show that, the induced drag reduces 15% that plane tototal resistance will decrease 6.5% and range increase 7.5%.At present, new research development aircraft, such as Boeing787 "dream" aircraft some airliners are in operation (Airbus A330, A340, Boeing737-800ER) so on, have adopted winglet.The reduction effect of winglet has been obviously.Because restricted by many factors, inclination angle, installation winglets airfoil, height, alula area root tip ratio on.So...

Transient change of the operating parameters has a serious influence on stability liquid annular seals. Take seals as research object, numerical method based six-degree-of-freedom (6DOF) to analyze dynamic response under gravity impact load. The variations force seal and pressure well axis trajectory in time history are investigated. different sealing clearance, viscosity rotor speed is also studied. results show that maximum direction will increase greatly very short then reduce rapidly....

Magnetically controlled capsule endoscope robot has developed rapidly. A key problem of is how to precisely control its movement in human body. Thus, the position and orientation parameters should be detected real time. This paper proposes a novel localization method based on simulated annealing-particle swarm optimization (SA-PSO) algorithm. system with 4×4 Hall sensor array designed used test accuracy method. Static experimental results show that average total error 1.64 mm, 1.08°. The at...

Non-contact manipulation technology has extensive application in the and fabrication of micro/nanomaterials. However, devices are often precise complex, operated only by professionals subject to site constraints. We propose a simple optoelectronic tweezer platform, which can be controlled remotely simply for microparticles at different scales, based on novel technique called optically-induced dielectrophoresis. In this work, we design set up platform develop full-function human-computer...

The bifurcation of a nongeneric homoclinic orbit (i.e., the comes from equilibrium along unstable manifold instead center manifold) connecting nonhyperbolic is investigated, and undergoes pitchfork bifurcation. existence (resp., nonexistence) an 1-periodic are established when does not happen, while as bifurcation, we obtain sufficient conditions for two or three heteroclinic orbits, so forth. Moreover, explore difference between generic one.

In the flight of hypersonic near space vehicle from 60km up to 100km high, influence real gas effect, rarefied and Mach number effect cannot be simulated completely by ground test.In this paper, selection computational model is introduced, then carried out numerical research on slip flow field characteristics coupling with chemical-equilibrium under large high altitude.