Harbin Institute of Technology

About: Harbin Institute of Technology is a education organization based out in Harbin, China. It is known for research contribution in the topics: Microstructure & Control theory. The organization has 88259 authors who have published 109297 publications receiving 1603393 citations. The organization is also known as: HIT.

Fault-Tolerant Sliding-Mode-Observer Synthesis of Markovian Jump Systems Using Quantized Measurements

Abstract: This paper investigates the design problem of sliding mode observer (SMO) using quantized measurements for a class of Markovian jump systems against actuator faults. Such a problem arises in modern networked-based digital systems, where data have to be transmitted and exchanged over a digital communication channel. In this paper, a new descriptor SMO approach using quantized signals is presented, in which a discontinuous input is synthesized to reject actuator faults by an offline static compensation of quantization effects. It is revealed that the lower bound on the density of a logarithmic quantizer is 1/3, under which the quantization effects could be compensated completely by using the SMO approach. Based on the proposed observer method, the asymptotical estimations of state vector and quantization errors can be obtained simultaneously. Finally, an example of a linearized model of an F-404 aircraft engine system is included to show the effectiveness of the presented observer design method.

A dendrite-suppressing composite ion conductor from aramid nanofibres

Abstract: Dendrite growth threatens the safety of batteries by piercing the ion-transporting separators between the cathode and anode. Finding a dendrite-suppressing material that combines high modulus and high ionic conductance has long been considered a major technological and materials science challenge. Here we demonstrate that these properties can be attained in a composite made from Kevlar-derived aramid nanofibres assembled in a layer-by-layer manner with poly(ethylene oxide). Importantly, the porosity of the membranes is smaller than the growth area of the dendrites so that aramid nanofibres eliminate 'weak links' where the dendrites pierce the membranes. The aramid nanofibre network suppresses poly(ethylene oxide) crystallization detrimental for ion transport, giving a composite that exhibits high modulus, ionic conductivity, flexibility, ion flux rates and thermal stability. Successful suppression of hard copper dendrites by the composite ion conductor at extreme discharge conditions is demonstrated, thereby providing a new approach for the materials engineering of solid ion conductors.

Large electrocaloric response and high energy-storage properties over a broad temperature range in lead-free NBT-ST ceramics

Abstract: The improvement of the electrocaloric effect (ECE) in (1−x)(Na0.5Bi0.5)TiO3−xSrTiO3 (NBT-ST) lead-free relaxor ferroelectric ceramics was determined by indirect measurements method and is reported here. The phase transition temperature can be reduced to room temperature by tuning the compositions of the (1−x)NBT-xST material. A large ECE (ΔTmax = 1.64 K, ΔSmax = 2.52 K and ΔT/ΔE = 0.33 K mm kV−1 at 50 kV cm−1) was obtained at 60 °C when x = 0.25. A suitable response over a broad temperature range from 30 °C to 70 °C can be obtained with x = 0.26 with very high cooling values (ΔT > 1 K). In addition, the 0.7NBT-0.3ST AFE-like bulk ceramic exhibited excellent temperature stability in its energy-storage properties from room temperature to 120 °C. The maximum value of the recoverable energy density was 0.65 J/cm3 obtained at 65 kV/cm. Taken together, these properties signified that (1−x)NBT-xST is a promising material for applications in cooling systems and energy-storage in the room temperature range.