Event-Triggered Distributed State Estimation for Multiagent Systems Under DoS Attacks.

This article investigates the problem of event-triggered distributed state estimation for linear multiagent systems under denial-of-service (DoS) attacks. In contrast to the previous studies where the agents have access to the measurements of their own states, an estimation algorithm is provided based on the measurements relative to the adjacent agents, and the considered DoS attacks jam each channel independently while the attack durations are constrained. To estimate the states and effectively schedule the information transmissions over the network possibly subject to malicious attacks, a prediction-based switching observer scheme with an event-triggered communication strategy is proposed, and the invalidation problem of the event-triggering mechanism caused by the DoS attacks is solved. Based on the decay rates of the Lyapunov function corresponding to different transmission modes, sufficient conditions for the stability of the estimation error dynamics are presented in the presence of DoS attacks. Finally, the effectiveness of the proposed strategy is demonstrated by simulation results.

Remote State Estimation for Nonlinear Systems via a Fading Channel: A Risk-Sensitive Approach.

This article investigates the problem of remote state estimation for nonlinear systems via a fading channel, where the packet losses may occur over the sensor-to-estimator communication network. The risk-sensitive (RS) approach is introduced to formulate the estimation problem with intermittent measurements such that an exponential cost criterion is minimized. Based on the reference measure method, the closed-form expression of the nonlinear RS estimator is derived. Moreover, stability conditions for the designed estimator are established by extending the contraction analysis of the linear cases. In contrast to the linear cases, a novel cost function is designed to obtain the finite-dimensional nonlinear estimate, which counteracts the linearization errors by treating them as model uncertainties. Simulation results illustrate that the proposed nonlinear estimator achieves better estimation qualities compared with the existing nonlinear minimum mean square error methods.

Capping a glass thin layer on the etched surface via plasma chemical vapor deposition for improving the laser damage performance of fused silica.

Buffered HF-based etching can effectively improve the laser damage resistance of the fused silica, but deep etching would cause the deteriorations in surface roughness and hardness, and decrease the laser-induced damage threshold. Capping a glass thin layer on the etched surface via plasma chemical vapor deposition in one step could overcome those deteriorations. We found that the deposition of the glass thin layer can further reduce the impurity element contamination and the PL intensity while retaining the low subsurface defect density as well as for the deeply etched sample. The surface quality, surface hardness and the laser damage resistance of the fused silica can be significantly improved by the glass thin layer, which reveals the potential application in high power laser facility.

[Spectroscopic Diagnosis of Atmosphere High Frequency Air Plasma Electron Temperature].

Atmosphere high frequency plasma is widely used due to its advantages of free of electrode pollution, high energy density high temperature and controllable redox conditions. As the key parameter in practical use, electron temperature of plasma is commonly diagnosed with atomic emission spectroscopy and calculated with Boltzmann plots. But electron temperatures calculated based on different lines by different researchers are usually not comparable due to transition probability data, application environment, instrumental error and data processing. This paper discussed influences of element and spectral range on calculated electron temperature for the first time in order to obtain reliable electron temperature of atmosphere high frequency air plasma. 7-channel high resolution fiber spectrometer with measurement range of 200~1 077 nm was used to test atomic emission spectroscopy. The experiment indicates that: The R square of fitted slope is 0.95 and standard deviation is the lowest using N Ⅰ lines in 738~940 nm and the calculated electron temperature is the most reliable; electron temperature calculated with Si and O lines are unreliable because they are easily binding to heavy SiO2 particles; reliable electron temperature also cannot be obtained by mixed Ar lines.

The role of the proteasome activator PA28 in MHC class I antigen processing.

The proteasome system is the major source for the generation of viral antigens and tumor antigens presented by major histocompatibility complex class I (MHC class I) molecules. A specific feature of the proteasomal antigen processing machinery is that five of its components are inducible by IFN-gamma. Two of these are the alpha and beta subunits of the proteasome activator PA28. Our results show that PA28 selectively up-regulates the presentation of viral MHC class I epitopes and that down regulation PA28 in tumor cells results in impaired presentation of a human TRP2 tumor antigen.