A Marr's Three‐Level Analytical Framework for Neuromorphic Electronic Systems

Neuromorphic electronics, an emerging field that aims for building electronic mimics of the biological brain, holds promise for reshaping the frontiers of information technology and enabling a more intelligent and efficient computing paradigm. As their biological brain counterpart, the neuromorphic electronic systems are complex, having multiple levels of organization. Inspired by David Marr's famous three-level analytical framework developed for neuroscience, the advances in neuromorphic electronic systems are selectively surveyed and given significance to these research endeavors as appropriate from the computational level, algorithmic level, or implementation level. Under this framework, the problem of how to build a neuromorphic electronic system is defined in a tractable way. In conclusion, the development of neuromorphic electronic systems confronts a similar challenge to the one neuroscience confronts, that is, the limited constructability of the low-level knowledge (implementations and algorithms) to achieve high-level brain-like (human-level) computational functions. An opportunity arises from the communication among different levels and their codesign. Neuroscience lab-on-neuromorphic chip platforms offer additional opportunity for mutual benefit between the two disciplines

Effects of Reed Biochar Mass Fraction on the Properties of Polypropylene/Reed Char Composites

Reed charcoal/polypropylene (RC/PP) composites were prepared by melt-blending and molding processes. The effects of RC addition (by mass fraction) on its mechanical properties were investigated and the mechanism characterized. The results showed that RC and PP were physically bonded and formed a mechanical interlocking matrix. The water absorption rate of these composites was <1% at 168 h. As the RC mass fraction increased, the tensile modulus, crystallinity, and energy storage modulus of the composites increased and then decreased, with the tensile modulus reaching a maximum of 679.4 MPa. The thermal decomposition rate peak and starting melt temperature increased by 14.8 and 2.5 °C, respectively, compared to pure PP, and the energy storage modulus reached a maximum of 3752.8 MPa at 40 wt% RC. The addition of RC in appropriate amounts improved the rigidity and thermal stability of these composites

A Robust Controller Design Methodology Addressing Challenges Under System Uncertainty

This paper proposes a generalized design methodology of a robust controller to mitigate the impact of system uncertainty on controller stability and performance which includes steady-state error, disturbance rejection, high-frequency noise attenuation and speed of dynamic response. The first step is to select the weighting functions that bound the transfer functions for the entire range of uncertainty. The second step is to form mathematical representation for both robust stability and robust performance. The third step is to conduct the robust H-infinity controller synthesis to generate the full-order controller, and then carry out order reduction and recheck of the design objectives. The last step is to select an optimized controller based on the multi-dimensional Pareto Front algorithm. The proposed method has been firstly applied to the current controller design of a grid-connected inverter with variable grid impedance, and secondly to the voltage controller design of an LLC resonant DC/DC converter with variable resonant capacitance. The results indicate that the selected optimal H-infinity controller has an overall more satisfactory performance in terms of stability, steady-state error, disturbance/noise rejection capability and dynamic performance, compared with conventional PI and PR controllers when there is a large variation of system parameters

Effect of Microstructure on Hydrogen Permeation in EA4T and 30CrNiMoV12 Railway Axle Steels

A comparative study was conducted to reveal the effect of microstructure on hydrogen permeation in the EA4T and 30CrNiMoV12 railway axle steels. Unlike the EA4T with its sorbite structure, 30CrNiMoV12 steel shows a typical tempered martensitic structure, in which a large number of fine, short, rod-like, and spherical carbides are uniformly dispersed at boundaries and inside laths. More importantly, this structure possesses plentifully strong hydrogen traps, such as nanosized Cr7C3, Mo2C, VC, and V4C3, thus resulting in a high density of trapping sites (N = 1.17 × 1022 cm−3). The hydrogen permeation experiments further demonstrated that, compared to EA4T, the 30CrNiMoV12 steel not only delivered minimally effective hydrogen diffusivity but also had a high hydrogen concentration. The activation energy for hydrogen diffusion of the 30CrNiMoV12 steel was greatly increased from 23.27 ± 1.94 of EA4T to 47.82 ± 2.14 kJ mol−1

Evaluation of coal petrophysics incorporating fractal characteristics by mercury intrusion porosimetry and low-field NMR

Mercury intrusion porosimetry (MIP) and low-field nuclear magnetic resonance (NMR) were combined to investigate pore-fracture structure and fractal characteristics of coals (0.93% < R-o,R- m < 2.77%), and their impacts on coal permeability were assessed using two newly-proposed models. The results indicate that coals with type I mercury intrusion/extrusion curve are beneficial to gas flow due to well-developed micro-fractures (73.9-86.74%) and high pore-fracture connectivity, whereas coals with type II and III curves are less conducive to gas flow because of non-uniform pore-fracture structure and poor connectivity. Based on NMR analysis, pore-fracture structure of low-rank bituminous coals (0.9% < R-o,R- m < 1.2%) presents irregular three T-2 peaks, whereas two and irregular three T-2 peaks simultaneously exist in other coals (1.2% < R-o,R- m < 2.8%). The variation of coal composition and gas generation process may have complex effects on pore-fracture structure during the coalification process. Moreover, MIP fractal dimension ranges from 2.265 to 2.873, whereas NMR fractal dimension varies from 2.744 to 2.976. Due to different sample morphology and fractal estimation methods, most of MIP fractal dimension is larger than NMR fractal dimension. A modified Kozeny-Carman equation was used to calculate MIP permeability, ranging from 3.62 x 10(-4) to 1.229 mD. The effect of mesopores on MIP permeability may be related to the gas flow pathway and interlinkage mechanism of adsorption pores and fractures. The NMR permeability was estimated by a movable porosity-permeability model (k(N) = 0.0045 * e(phi NM/0.6851)+0.037), ranging from 0.043 to 2.767 mD. The NMR permeability should be related to movable fluid space and pore-fracture connectivity, and micro-fractures can largely contribute to free fluid volume

Establishment and validation of early prediction model for hypertriglyceridemic severe acute pancreatitis

Abstract Background The prevalence of hypertriglyceridaemia-induced acute pancreatitis (HTG-AP) is increasing due to improvements in living standards and dietary changes. However, currently, there is no clinical multifactor scoring system specific to HTG-AP. This study aimed to screen the predictors of HTG-SAP and combine several indicators to establish and validate a visual model for the early prediction of HTG-SAP. Methods The clinical data of 266 patients with HTG-SAP were analysed. Patients were classified into severe (N = 42) and non-severe (N = 224) groups according to the Atlanta classification criteria. Several statistical analyses, including one-way analysis, least absolute shrinkage with selection operator (LASSO) regression model, and binary logistic regression analysis, were used to evaluate the data. Results The univariate analysis showed that several factors showed no statistically significant differences, including the number of episodes of pancreatitis, abdominal pain score, and several blood diagnostic markers, such as lactate dehydrogenase (LDH), serum calcium (Ca2+), C-reactive protein (CRP), and the incidence of pleural effusion, between the two groups (P  0.05). The decision curve analysis plot suggested that clinical intervention can benefit patients when the model predicts that they are at risk for developing HTG-SAP. Conclusions CRP, LDH, Ca2+, and ascites are independent predictors of HTG-SAP. The prediction model constructed based on these indicators has a high accuracy, sensitivity, consistency, and practicability in predicting HTG-SAP

Numerical Analysis of Natural Gas Injection in Shougang Jingtang Blast Furnace

A static model of blast furnace operation of natural gas (NG) injection was developed. The effect of NG injection on the raceway adiabatic flame temperature, the amount and composition of bosh gas, the direct reduction degree and fuel ratio were studied. The results showed that under no thermal compensation, the heat loss of the whole blast furnace increases, which means the heat surplus of the whole furnace is sufficient. However, the heat in the high-temperature zone of the blast furnace is insufficient, showing the characteristics of “cold at bottom and hot at the top”. Based on the comparison of heat loss in the high-temperature zone after NG injection with the reference condition, if the heat loss is consistent with the reference case, the suitable NG injection volumes are 17.3, 34.6, 52 and 69.3 m3/t when the coal ratio is reduced by 20, 40, 60 and 80 kg/t, respectively. With the increase of the suitable NG injection volumes, the adiabatic flame temperature gradually decreases, the amount of bosh gas slightly increases, and the overall fuel ratio reduces gradually. The effect of other thermal compensation operations, such as increasing blast temperature and addition of oxygen on the NG injection, were also investigated. The findings of this work can be used as a theoretical basis to guide plant operations for NG injection in blast furnaces

Study on Regulation Mechanism of Tomato Root Growth in Greenhouse under Cycle Aerated Subsurface Drip Irrigation

Aerobic irrigation can effectively improve the oxygen environment in the root zone, and enhance crop quality and yield. However, how aerobic irrigation regulates root growth has not been elucidated. In this study, tomato plants were irrigated with three levels of oxygen (high, medium, and low) under underground drip irrigation. The morphology, activity, transcriptome, and hormone content of tomato roots under oxygen irrigation were analyzed. We found that the aeration irrigation significantly promoted root development. Notably, in the high-aeration irrigation treatment (HAI), the total root length, total surface area, total volume, and root activity were 12.41%, 43.2%, 79.1%, and 24.15% higher than in the non-aeration irrigation treatment (CK), respectively. The transcriptome of tomato roots under aeration irrigation was determined with a total of 272 differentially expressed genes (DEGs), including 131 up-regulated and 141 down-regulated genes. The Kyoto encyclopedia of genes and genomes (KEGG) analysis revealed that the DEGs were enriched mainly in the metabolic pathways and plant hormone signal transduction. Among the plant hormone signal transduction, 50% of DEGs belonged to IAA signal-related genes and were upregulated. LC-MS analysis showed that the content of auxin hormones in the tomato roots subjected to aeration irrigation was significantly higher than that in CK. The content of Indole-3-acetic acid (IAA), Indole-3-carboxylic acid (ICA) and Indole-3-carboxaldehyde (ICAld) were 2.3, 2.14 and 1.45 times higher than those of the CK, but insignificant effects were exerted on the contents of cytokinins, salicylic acid, jasmonic acid, abscisic acid, and ethylene. Meanwhile, the key enzyme of auxin synthesis flavin monooxygenase (YUCCA) was significantly up-regulated. The aforementioned results show that aeration irrigation may promote the growth and development of roots by auxin regulation