scholarly journals Metaheuristics in the Optimization of Cryptographic Boolean Functions

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 1052 ◽  
Author(s):  
Isaac López-López ◽  
Guillermo Sosa-Gómez ◽  
Carlos Segura ◽  
Diego Oliva ◽  
Omar Rojas
Keyword(s):  
Boolean Functions ◽  
High Performance ◽  
Memetic Algorithm ◽  
Hadamard Transform ◽  
Gradual Change ◽  
Exploration And Exploitation ◽  
High Entropy ◽  
Lower Entropy ◽  
Optimization Mechanism ◽  
Proper Balance

Generating Boolean Functions (BFs) with high nonlinearity is a complex task that is usually addresses through algebraic constructions. Metaheuristics have also been applied extensively to this task. However, metaheuristics have not been able to attain so good results as the algebraic techniques. This paper proposes a novel diversity-aware metaheuristic that is able to excel. This proposal includes the design of a novel cost function that combines several information from the Walsh Hadamard Transform (WHT) and a replacement strategy that promotes a gradual change from exploration to exploitation as well as the formation of clusters of solutions with the aim of allowing intensification steps at each iteration. The combination of a high entropy in the population and a lower entropy inside clusters allows a proper balance between exploration and exploitation. This is the first memetic algorithm that is able to generate 10-variable BFs of similar quality than algebraic methods. Experimental results and comparisons provide evidence of the high performance of the proposed optimization mechanism for the generation of high quality BFs.

Porous spinel-type (Al0.2CoCrFeMnNi)0.58O4-δ high-entropy oxide as a novel high-performance anode material for lithium-ion batteries

2021 ◽  
Vol 56 (13) ◽  
pp. 8127-8142
Author(s):  
Hou-Zheng Xiang ◽  
Hong-Xiang Xie ◽  
Yu-Xue Chen ◽  
Hui Zhang ◽  
Aiqin Mao ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Anode Material ◽  
High Performance ◽  
Lithium Ion ◽  
Spinel Type ◽  
High Entropy

scholarly journals Coherent Precipitation and Strengthening in Compositionally Complex Alloys: A Review

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 878 ◽  
Author(s):  
Qing Wang ◽  
Zhen Li ◽  
Shujie Pang ◽  
Xiaona Li ◽  
Chuang Dong ◽  
...  
Keyword(s):  
Solid Solution ◽  
High Performance ◽  
Particle Morphology ◽  
Precipitation Strengthening ◽  
Second Phase ◽  
High Entropy ◽  
Second Phase Particles ◽  
Alloy Strength ◽  
Solid Solution Matrix ◽  
The Relationship

High-performance conventional engineering materials (including Al alloys, Mg alloys, Cu alloys, stainless steels, Ni superalloys, etc.) and newly-developed high entropy alloys are all compositionally-complex alloys (CCAs). In these CCA systems, the second-phase particles are generally precipitated in their solid-solution matrix, in which the precipitates are diverse and can result in different strengthening effects. The present work aims at generalizing the precipitation behavior and precipitation strengthening in CCAs comprehensively. First of all, the morphology evolution of second-phase particles and precipitation strengthening mechanisms are introduced. Then, the precipitation behaviors in diverse CCA systems are illustrated, especially the coherent precipitation. The relationship between the particle morphology and strengthening effectiveness is discussed. It is addressed that the challenge in the future is to design the stable coherent microstructure in different solid-solution matrices, which will be the most effective approach for the enhancement of alloy strength.

Solid State Manufacture of High Entropy Alloys-Preliminary Studies

MRS Advances ◽  
2017 ◽  
Vol 2 (26) ◽  
pp. 1375-1380 ◽  
Author(s):  
M B D Ellis ◽  
G R Doughty
Keyword(s):  
Solid State ◽  
High Performance ◽  
Alloying Elements ◽  
Liquid Density ◽  
High Entropy Alloys ◽  
Next Generation ◽  
Molten Salt Electrolysis ◽  
High Entropy ◽  
State Diffusion ◽  
Environmentally Friendly Process

AbstractFor the past ten years Metalysis have produced tantalum, titanium and titanium alloy powders for high performance applications using their solid state salt electrolysis process. This low energy and environmentally friendly process is now being used to manufacture the next generation of High Entropy Alloys (HEAs).In most cases the manufacture of HEAs involves high temperatures which put all of the alloying elements into the liquid phase. This can lead to numerous problems and restrict the number of HEAs which can be made, particularly the alloys where one needs to combine low melting point elements with refractory elements and also where there are significant liquid density differences between the constituents causing melt segregation.The aim is to present the preliminary work carried out by Metalysis and to show how the solid state diffusion process based on molten salt electrolysis lends itself to the industrial scale manufacture of the next generation of HEAs. This study will focus on the HEAs whose constituent alloying elements have large differences in both their melting points and liquid densities, for example, chromium, niobium, tantalum, titanium and aluminum.

scholarly journals Different-Shaped Ultrafine MoNbTaW HEA Powders Prepared via Mechanical Alloying

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1250 ◽  
Author(s):  
Yonggang Tong ◽  
Peibu Qi ◽  
Xiubing Liang ◽  
Yongxiong Chen ◽  
Yongle Hu ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
High Performance ◽  
Solution Phase ◽  
High Entropy Alloy ◽  
Solid Solution Phase ◽  
Body Centered Cubic ◽  
Homogeneous Microstructure ◽  
High Entropy ◽  
Single Body ◽  
Different Shapes

Different-shaped ultrafine MoNbTaW high-entropy alloy powders were firstly prepared by a convenient mechanical alloying method. The phase composition and microstructure of the powders were characterized. The powders are ultrafine with nano-sized grains and a good homogeneous microstructure. All the powders have a single body-centered cubic solid solution phase and form the high-entropy alloy during mechanical alloying. These powders with different shapes are quite attractive for developing high-performance MoNbTaW high-entropy alloy bulk and coatings combined with a following sintering, spraying, or additive manufacturing technique.

scholarly journals Dwindling of Real Power Loss by Enriched Big Bang-Big Crunch Algorithm

2018 ◽  
Vol 7 (4) ◽  
pp. 190
Author(s):  
K. Lenin
Keyword(s):  
Power Loss ◽  
Reactive Power ◽  
Big Bang ◽  
Local Optimum ◽  
Exploration And Exploitation ◽  
Real Power ◽  
Big Crunch ◽  
Improved Performance ◽  
Power Problem ◽  
Proper Balance

In this paper, Enriched Big Bang-Big Crunch (EBC) algorithm is proposed to solve the reactive power problem. The problem of converging to local optimum solutions occurred for the Bang-Big Crunch (BB-BC) approach due to greedily looking around the best ever found solutions. The proposed algorithm takes advantages of typical Big Bang-Big Crunch (BB-BC) algorithm and enhances it with the proper balance between exploration and exploitation factors. Proposed EBC algorithm has been tested in standard IEEE 118 & practical 191 bus test systems and simulation results show clearly the improved performance of the proposed algorithm in reducing the real power loss.

scholarly journals High-performance Multiplexer-based Logic Synthesis Using Pass-transistor Logic

VLSI Design ◽  
2002 ◽  
Vol 15 (1) ◽  
pp. 417-426 ◽  
Author(s):  
Shen-Fu Hsiao ◽  
Jia-Siang Yeh ◽  
Da-Yen Chen
Keyword(s):  
Boolean Functions ◽  
High Performance ◽  
Voltage Drop ◽  
Critical Path ◽  
Logic Synthesis ◽  
Path Delay ◽  
Minimum Width ◽  
Pass Transistor ◽  
Pass Transistor Logic ◽  
Function Sharing

An automatic logic/circuit synthesizer is developed which takes several Boolean functions as input and generates netlist output with basic composing cells from the pass-transistor cell library containing only two types of cells: 2-to-1 multiplexers and inverters. The synthesis procedure first constructs efficient binary decision diagrams (BDDs) for these Boolean functions considering both multi-function sharing and minimum width. Each node in the BDD trees is realized by using a 2-to-1 multiplexer (MUX) of proper driving capability designed pass-transistor logic. The inverters are then inserted all along the MUX paths in order to improve the speed performance and to alleviate the voltage-drop problem. Several methods are proposed to reduce the critical path delay in the multiplexer-chains for generation of faster circuits. Compared to the recently proposed pass-transistor-based top-down design, our synthesizer has better speed and area performance due to the reduced number of cascaded inverters.

scholarly journals Ultrastrong lightweight compositionally complex steels via dual-nanoprecipitation

2020 ◽  
Vol 6 (46) ◽  
pp. eaba9543 ◽  
Author(s):  
Zhangwei Wang ◽  
Wenjun Lu ◽  
Huan Zhao ◽  
Christian H. Liebscher ◽  
Junyang He ◽  
...  
Keyword(s):  
High Performance ◽  
Energy Savings ◽  
Tensile Elongation ◽  
High Strength ◽  
Metallic Materials ◽  
Principal Element ◽  
High Entropy ◽  
Solid Solution Strengthening ◽  
New Class ◽  
Solution Strengthening

High-performance lightweight materials are urgently needed, given the pressing quest for weight reduction and the associated energy savings and emission reduction. Here, by incorporating the multi–principal element feature of compositionally complex alloys, we develop the concept of lightweight steels further and propose a new class of compositionally complex steels (CCSs). This approach allows us to use the high solid solution strengthening and shift the alloys’ compositions into previously unattainable phase regions where both nanosized shearable κ-carbides and non-shearable B2 particles are simultaneously formed. The achievement of dual-nanoprecipitation in our CCSs leads to materials with ultrahigh specific tensile strength (up to 260 MPa·cm3 g−1) and excellent tensile elongation (13 to 38%), a combination outperforming all other high-strength high-entropy alloys and advanced lightweight steels. Our concept of CCSs is thus useful for guiding the design of ultrastrong lightweight metallic materials.

High entropy alloy: A promising matrix for high-performance tungsten heavy alloys

2019 ◽  
Vol 777 ◽  
pp. 1184-1190 ◽  
Author(s):  
Shangcheng Zhou ◽  
Yao-Jian Liang ◽  
Yichao Zhu ◽  
Ruizhi Jian ◽  
Benpeng Wang ◽  
...  
Keyword(s):  
High Performance ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Heavy Alloys ◽  
Tungsten Heavy Alloys

Symmetry conditions of Boolean functions in complex Hadamard transform

1998 ◽  
Vol 34 (17) ◽  
pp. 1634 ◽  
Author(s):  
S. Rahardja ◽  
B.J. Falkowski
Keyword(s):  
Boolean Functions ◽  
Hadamard Transform
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