Adaptive Robust Actuator Fault Accommodation for a Class of Uncertain Nonlinear Systems with Unknown Control Gains

An adaptive robust fault tolerant control approach is proposed for a class of uncertain nonlinear systems with unknown signs of high-frequency gain and unmeasured states. In the recursive design, neural networks are employed to approximate the unknown nonlinear functions, K-filters are designed to estimate the unmeasured states, and a dynamical signal and Nussbaum gain functions are introduced to handle the unknown sign of the virtual control direction. By incorporating the switching function σ algorithm, the adaptive backstepping scheme developed in this paper does not require the real value of the actuator failure. It is mathematically proved that the proposed adaptive robust fault tolerant control approach can guarantee that all the signals of the closed-loop system are bounded, and the output converges to a small neighborhood of the origin. The effectiveness of the proposed approach is illustrated by the simulation examples

Numerical Simulation Research on the Anchor Last Deployment of Marine Submersible Buoy System Based on VOF Method

Marine submersible buoy systems are widely-used equipment for ocean resource development. The marine submersible buoy system studied in this paper consists of the submersible buoy, the battery compartment, the anchor block, the mooring line, and the power supply cable. To study the mechanical behavior and obtain the speed variation of each component during the anchor last deployment, this paper establishes the free surface computational fluid dynamics model of marine submersible buoy systems based on the VOF method. This model includes the incompressible Navier–Stokes equations, the Renormalization-Group turbulence model, and the fractional areas/volume obstacle representation method. The free fluid surface is tracked using the VOF method. The lumped mass method is used to simulate the mooring line and power supply cable. The results showed that the tension forces increase when the mooring lines were straightened. Subsequently, the tension forces gradually decrease with oscillations. After the anchor block sinks to the sea floor, the positive buoyancy of the battery compartment and the buoy will cause large tension on the mooring line and power supply cable

Pneumatic Performance Study of a High Pressure Ejection Device Based on Real Specific Energy and Specific Enthalpy

In high-pressure dynamic thermodynamic processes, the pressure is much higher than the air critical pressure, and the temperature can deviate significantly from the Boyle temperature. In such situations, the thermo-physical properties and pneumatic performance can’t be described accurately by the ideal gas law. This paper proposes an approach to evaluate the pneumatic performance of a high-pressure air catapult launch system, in which esidual functions are used to compensate the thermal physical property uncertainties of caused by real gas effects. Compared with the Nelson-Obert generalized compressibility charts, the precision of the improved virial equation of state is better than Soave-Redlich-Kwong (S-R-K) and Peng-Robinson (P-R) equations for high pressure air. In this paper, the improved virial equation of state is further used to establish a compressibility factor database which is applied to evaluate real gas effects. The specific residual thermodynamic energy and specific residual enthalpy of the high-pressure air are also derived using the modified corresponding state equation and improved virial equation of state which are truncated to the third virial coefficient. The pneumatic equations are established on the basis of the derived residual functions. The comparison of the numerical results shows that the real gas effects are strong, and the pneumatic performance analysis indicates that the real dynamic thermodynamic process is obviously different from the ideal one

Correction: External Quality Assessment of Molecular Detection of Ebola Virus in China.

<p>Correction: External Quality Assessment of Molecular Detection of Ebola Virus in China</p

A schematic map of the experimental procedure.

<p>A schematic map of the experimental procedure.</p

External Quality Assessment of Molecular Detection of Ebola Virus in China

<div><p>In 2014, Ebola hemorrhagic fever broke out in West Africa. As contact between China and West Africa is frequent, the possibility that Ebola virus would enter China was high. Thus, an external assessment of the quality of Ebola virus detection was organized by the National Center for Clinical Laboratories in China. Virus-like particles encapsulating known sequences of epidemic strains of Ebola virus from 2014 were prepared as positive quality controls. The sample panel, which was composed of seven positive and three negative samples, was dispatched to 19 laboratories participating in this assessment of Ebola virus detection. Accurate detection was reported at 14 of the 19 participating laboratories, with a sensitivity of 91.43% and a specificity of 100%. Four participants (21.05%) reported false-negative results and were classified as “acceptable.” One participant (5.26%) did not detect any positive samples and was thus classified as “improvable.” Based on the results returned, the ability to detect weakly positive Ebola specimens should be improved. Furthermore, commercial assays and the standard primers offered by the Chinese Centers for Disease Control and Prevention were found to be most accurate and dependable for Ebola detection. A two-target detection approach is recommended for Ebola screening; this approach could reduce the probability of false-negative results. Additionally, standardization of operations and punctual adjustment of instruments are necessary for the control and prevention of Ebola virus.</p></div

The primers and probes provided by Chinese CDC.

<p>The primers and probes provided by Chinese CDC.</p