Critical Technology Events in the Development of the Abrams Tank: Project Hindsight Revisited

Three-dimensional (3D) printing is regarded as a critical technology in material engineering for biomedical applications. From a previous report, silk fibroin (SF) has been used as a biomaterial for tissue engineering due to its biocompatibility, biodegradability, non-toxicity and robust mechanical properties which provide a potential as material for 3D-printing. In this study, SF-based hydrogels with different formulations and SF concentrations (1–3%wt) were prepared by natural gelation (SF/self-gelled), sodium tetradecyl sulfate-induced (SF/STS) and dimyristoyl glycerophosphorylglycerol-induced (SF/DMPG). From the results, 2%wt SF-based (2SF) hydrogels showed suitable properties for extrusion, such as storage modulus, shear-thinning behavior and degree of structure recovery. The 4-layer box structure of all 2SF-based hydrogel formulations could be printed without structural collapse. In addition, the mechanical stability of printed structures after three-step post-treatment was investigated. The printed structure of 2SF/STS and 2SF/DMPG hydrogels exhibited high stability with high degree of structure recovery as 70.4% and 53.7%, respectively, compared to 2SF/self-gelled construct as 38.9%. The 2SF/STS and 2SF/DMPG hydrogels showed a great potential to use as material for 3D-printing due to its rheological properties, printability and structure stability.

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A Nonlinear Maximum Correntropy Information Filter for High-Dimensional Neural Decoding

Entropy ◽

10.3390/e23060743 ◽

2021 ◽

Vol 23 (6) ◽

pp. 743

Author(s):

Xi Liu ◽

Shuhang Chen ◽

Xiang Shen ◽

Xiang Zhang ◽

Yiwen Wang

Keyword(s):

State Estimation ◽

Measurement Model ◽

High Dimensional ◽

Neural Firing ◽

The Neural Network ◽

Information Filter ◽

Critical Technology ◽

Dimensional Measurements ◽

Non Gaussian ◽

Low Dimensional

Neural signal decoding is a critical technology in brain machine interface (BMI) to interpret movement intention from multi-neural activity collected from paralyzed patients. As a commonly-used decoding algorithm, the Kalman filter is often applied to derive the movement states from high-dimensional neural firing observation. However, its performance is limited and less effective for noisy nonlinear neural systems with high-dimensional measurements. In this paper, we propose a nonlinear maximum correntropy information filter, aiming at better state estimation in the filtering process for a noisy high-dimensional measurement system. We reconstruct the measurement model between the high-dimensional measurements and low-dimensional states using the neural network, and derive the state estimation using the correntropy criterion to cope with the non-Gaussian noise and eliminate large initial uncertainty. Moreover, analyses of convergence and robustness are given. The effectiveness of the proposed algorithm is evaluated by applying it on multiple segments of neural spiking data from two rats to interpret the movement states when the subjects perform a two-lever discrimination task. Our results demonstrate better and more robust state estimation performance when compared with other filters.

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Study of a Computer-Based Control System with Fault-Tolerant and Fail-Safe Behavior

Information Technologies and Control ◽

10.1515/itc-2016-0015 ◽

2015 ◽

Vol 13 (3-4) ◽

pp. 34-45

Author(s):

Mariya Hristova

Keyword(s):

Probabilistic Models ◽

Fault Tolerant ◽

General Scheme ◽

Base System ◽

Critical Systems ◽

Critical Technology ◽

Previous Edition ◽

System 2 ◽

Software And Hardware ◽

Fail Safe

Abstract The software and hardware of Safety Critical Systems - SCS, which control special critical technology process or operation, are subject of enhanced requirements for reliability and inadmissibility of any incorrect controlling influences (safety) after failures. This paper suggests and investigates a hybrid computerbased fail-safe/fault-tolerance FST-structure with single reservation, which has the qualities to meet these requirements. The base system 2 ∨ 2, based on which it is built, is studied in the previous edition of Information Technjlogies and Control. For derivation of probabilistic models through which to establish the efficiency of the strutucral redundancy in a fault-tolerant structure, in this paper are used the published results. Formulas are derived for the probability of failure-free operation (availability coefficient), for safe failure and for unidentified (dangerous) failure. Models are found for calculation of the enhancement of reliability and the variation of safety relative to the base system 2 ∨ 2. Subject of analysis are type software and hardware modifications of the proposed general scheme used in the practice of different companies, which manufacture and operate SCSs. It is proven that at the expense of acceptable hardware redundancy and insignificant increase of dangerous failures the probability of interruption of the operation of the FST- system and its down-time due to failure may decrease by tenths of thousands of times.

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