Multi-objective evolutionary design and knowledge discovery of logic circuits based on an adaptive genetic algorithm

Evolutionary design of circuits (EDC), an important branch of evolvable hardware which emphasizes circuit design, is a promising way to realize automated design of electronic circuits. In order to improve evolutionary design of logic circuits in efficiency, scalability and capability of optimization, a genetic algorithm based novel approach was developed. It employs a gate-level encoding scheme that allows flexible changes of functions and interconnections of logic cells comprised, and it adopts a multi-objective evaluation mechanism of fitness with weight-vector adaptation and circuit simulation. Besides, it features an adaptation strategy that enables crossover probability and mutation probability to vary with individuals' diversity and genetic-search process. It was validated by the experiments on arithmetic circuits especially digital multipliers, from which a few functionally correct circuits with novel structures, less gate count and higher operating speed were obtained. Some of the evolved circuits are the most efficient or largest ones (in terms of gate count or problem scale) as far as we know. Moreover, some novel and general principles have been discerned from the EDC results, which are easy to verify but difficult to dig out by human experts with existing knowledge. These results argue that the approach is promising and worthy of further research.     

A new automated design and optimization method of CMOS logic circuits based on Modified Imperialistic Competitive Algorithm

This paper proposes a novel evolutionary approach based on modified Imperialist Competitive Algorithm for combinational logic circuits designing and optimization. The Imperialist Competitive Algorithm operates on real values and is not applicable to logic circuits optimization problems. So a modified version of ICA is proposed to overcome this shortcoming. Modification of the algorithm depends on random cell replacement between Imperialist and its colonies as assimilation policy. Also a multi-objective evaluation mechanism in the form of a weighted cost function is introduced to obtain optimized circuits in case of circuit area and propagation delay. To evaluate the effectiveness of this method some general benchmark circuits are used in which the circuits with fewer logic cells (minimized space) and lower propagation delay are obtained. The simulation results of our proposed method are compared with some conventional and heuristic methods. Simulation results show that our proposed method significantly improves the performance factor which represents both circuit area and propagation delay.     

A module-level three-stage approach to the evolutionary design of sequential logic circuits

In this study, we propose a module-level three-stage approach (TSA) to optimize the evolutionary design for synchronous sequential circuits. TSA has a three stages process, involving a genetic algorithm (GA), a pre-evolution, and a re-evolution. In the first stage, the GA simplifies the number of states and automatically searches the state assignment that can produce the circuit with small complexity. Then, the second stage evolves a set of high-performing circuits to acquire frequently evolved blocks, which will be re-used for more compact and simple solutions in the next stage. In this stage, a genetic programming (GP) is proposed for evolving the high-performing circuits and data mining is used as a finder of frequently evolved blocks in these circuits. In the final stage, the acquired blocks are encapsulated into the function and terminal set to produce a new population in the re-evolution. The blocks are expected to make the convergence faster and hence efficiently reduce the complexity of the evolved circuits. Seven problems of three types—sequence detectors, modulo-n counters and ISCAS89 circuits—are used to test our three-stage approach. The simulation results for these experiments are promising, and our approach is shown to be better than the other methods for sequential logic circuits design in terms of convergence time, success rate, and maximum fitness improvement across generations.     

Evolutionary morphogenesis for multi-cellular systems

With a gene required for each phenotypic trait, direct genetic encodings may show poor scalability to increasing phenotype length. Developmental systems may alleviate this problem by providing more efficient indirect genotype to phenotype mappings. A novel classification of multi-cellular developmental systems in evolvable hardware is introduced. It shows a category of developmental systems that up to now has rarely been explored. We argue that this category is where most of the benefits of developmental systems lie (e.g. speed, scalability, robustness, inter-cellular and environmental interactions that allow fault-tolerance or adaptivity). This article describes a very simple genetic encoding and developmental system designed for multi-cellular circuits that belongs to this category. We refer to it as the morphogenetic system. The morphogenetic system is inspired by gene expression and cellular differentiation. It focuses on low computational requirements which allows fast execution and a compact hardware implementation. The morphogenetic system shows better scalability compared to a direct genetic encoding in the evolution of structures of differentiated cells, and its dynamics provides fault-tolerance up to high fault rates. It outperforms a direct genetic encoding when evolving spiking neural networks for pattern recognition and robot navigation. The results obtained with the morphogenetic system indicate that this “minimalist” approach to developmental systems merits further study.

Quantum-inspired design of resilient substitution boxes: From coding to hardware implementation

S-boxes constitute a cornerstone component in symmetric-key cryptographic algorithms, such as DES and AES encryption systems. In block ciphers, they are typically used to obscure the relationship between the plaintext and the ciphertext. Non-linear and non-correlated S-boxes are the most secure against linear and differential cryptanalysis. In this paper, we focus on a twofold objective: first, we evolve regular S-boxes with high non-linearity and low auto-correlation properties; then automatically generate evolvable hardware for the obtained S-box. Targeting the former, we use a quantum-inspired evolutionary algorithm to optimize regularity, non-linearity and auto-correlation, which constitute the three main desired properties in resilient S-boxes. Pursuing the latter, we exploit the same algorithm to automatically generate the evolvable hardware designs of substitution boxes that minimize hardware space and encryption/decryption time, which form the two main hardware characteristics. We compare our results against existing and well-known designs, which were produced by using conventional methods as well as through genetic algorithm. We will show that our approach provides higher quality S-boxes coding as well as circuits.     

A pareto-based evolutionary algorithm using decomposition and truncation for dynamic multi-objective optimization

Maintaining a balance between convergence and diversity of the population in the objective space has been widely recognized as the main challenge when solving problems with two or more conflicting objectives. This is added by another difficulty of tracking the Pareto optimal solutions set (POS) and/or the Pareto optimal front (POF) in dynamic scenarios. Confronting these two issues, this paper proposes a Pareto-based evolutionary algorithm using decomposition and truncation to address such dynamic multi-objective optimization problems (DMOPs). The proposed algorithm includes three contributions: a novel mating selection strategy, an efficient environmental selection technique and an effective dynamic response mechanism. The mating selection considers the decomposition-based method to select two promising mating parents with good diversity and convergence. The environmental selection presents a modified truncation method to preserve good diversity. The dynamic response mechanism is evoked to produce some solutions with good diversity and convergence whenever an environmental change is detected. In the experimental studies, a range of dynamic multi-objective benchmark problems with different characteristics were carried out to evaluate the performance of the proposed method. The experimental results demonstrate that the method is very competitive in terms of convergence and diversity, as well as in response speed to the changes, when compared with six other state-of-the-art methods.     

Automated synthesis of multiple analog circuits using evolutionary computation for redundancy-based fault-tolerance

Analog circuits are one of the most important parts of modern electronic systems and the failure of electronic hardware presents a critical threat to the completion of modern aircraft, spacecraft, and robot missions. Compared to digital circuits, designing fault-tolerant analog circuits is a difficult and knowledge-intensive task. A simple but powerful method for robustness is a redundancy approach to use multiple circuits instead of single one. For example, if component failures occur, other redundant components can replace the functions of broken parts and the system can still work. However, there are several research issues to make the redundant system automatically. In this paper, we used evolutionary computation to generate multiple analog circuits automatically and then we combined the solutions to generate robust outputs. Evolutionary computation is a natural way to produce multiple redundant solutions because it is a population-based search. Experimental results on the evolution of the low-pass, high-pass and band-stop filters show that the combination of multiple evolved analog circuits produces results that are more robust than those of the best single circuit.     

Simplifying the automatic design of a fuzzy logic controller using evolutionary programming

With the availability of a wide range of Evolutionary Algorithms such as Genetic Algorithms, Evolutionary Programming, Evolutionary Strategies and Differential Evolution, every conceivable aspect of the design of a fuzzy logic controller has been optimized and automated. Although there is no doubt that these automated techniques can produce an optimal fuzzy logic controller, the structure of such a controller is often obscure and in many cases these optimizations are simply not needed. We believe that the automatic design of a fuzzy logic controller can be simplified by using a generic rule base such as the MacVicar-Whelan rule base and using an evolutionary algorithm to optimize only the membership functions of the fuzzy sets. Furthermore, by restricting the overlapping of fuzzy sets, using triangular membership functions and singletons, and reducing the number of parameters to represent the membership functions, the design can be further simplified. This paper describes this method of simplifying the design and some experiments performed to ascertain its validity.     

异步时序逻辑电路的分析与设计

异步时序逻辑电路状态的改变必须考虑外部输入信号以及对应存储器的时钟端或控制端有无信号作用,这是分析与设计的一个难点。针对这一难点进行了详细的讨论,通过系统框图给出了分析和设计的一般步骤;总结了分析和设计中对一般问题的解决方法以及应该注意的问题。通过举例验证了该方法的正确性、通用性和快速性。     

Routine automated synthesis of five patented analog circuits using genetic programming

This article reports on a project in which we browsed patents issued after January 1, 2000 to commercial enterprises or university research institutions for analog electrical circuits. We then employed genetic programming to automatically design (synthesize) entities that duplicated the functionality of five post-2000 issued patents. The automated method works from a high-level statement of the circuits intended function. The article addresses the question of what is actually delivered by the operation of the artificial problem-solving method in relation to the amount of intelligence that is supplied by the humans employing the method (something we refer to as the yield of an automated method). The article also addresses the question of the routineness of the artificial problem-solving method – that is, the amount of effort required to make the transition from problem to problem within a particular domain. The conclusion is that the artificial method routinely delivers high-yield, human-competitive (i.e., previously patented) results.     

Multi-objective evolutionary approaches for intelligent design of sensor networks in the petrochemical industry

The design of optimal sensor networks for an industrial process is a complex problem that requires the resolution of several tasks with a high level of expertise. The first of these subproblems consists in selecting an initial sensor network as the starting point for the instrumentation design. This particular task constitutes a combinatorial optimization problem, where several goals are prosecuted by the designer. Therefore, the initialization procedure can be defined as a multi-objective optimization problem. In this paper, the use of multi-objective evolutionary approaches to assist experts in the design of an initial sensor network is proposed and analyzed. The aim is to contrast the advantages and limitations of Pareto and non-Pareto techniques in the context of this industrial application. The algorithms consider objectives related to cost, reliability and level of information associated with a sensor network. The techniques were evaluated by means of a comparative analysis for a strongly non-linear mathematical model that represents an ammonia synthesis plant. Results have been contrasted in terms of the set coverage and spacing metrics. As a final conclusion, the non-Pareto strategy converged closer to the Pareto front than the Pareto-based algorithms. In contrast, the Pareto-based algorithms achieved better relative distance among solutions than the non-Pareto method. In all cases, the use of evolutionary computation is useful for the expert to take the final decision on the preferred initial sensor network.     

A simulated annealing method based on a specialised evolutionary algorithm

The flexible architecture of evolutionary algorithms allows specialised models to be obtained with the aim of performing as other search methods do, but more satisfactorily. In fact, there exist several evolutionary proposals in the literature that play the role of local search methods. In this paper, we make a step forward presenting a specialised evolutionary approach that carries out a search process equivalent to the one of simulated annealing. An empirical study comparing the new model with classic simulated annealing methods, hybrid algorithms and state-of-the-art optimisers concludes that the new alternative scheme for combining ideas from simulated annealing and evolutionary algorithms introduced by our proposal may outperform this kind of hybrid algorithms, and achieve competitive results with regard to proposals presented in the literature for binary-coded optimisation problems.     

基于自适应免疫进化算法的逻辑电路设计*

针对现有进化算法在进行逻辑电路设计时存在的进化缓慢和容易陷入局部解等问题,提出一种自适应免疫进化算法（adaptive immune evolutionary algorithm,AIEA）。该算法引入了免疫记忆机制和抗体差异调节算子,能够很好地保证个体的多样性,有利于跳出局部最优解;通过采用自适应交叉率和变异率,提高了算法的搜索能力和收敛速度。通过与多目标进化算法（MOEA）、简单免疫算法（SIA）的实验比较,证明了该自适应免疫进化算法的有效性。     

模拟电路的多目标优化与演化设计

对模拟电路设计中涉及的多个目标进行了定义与量化,并针对这些目标提出一种面向模拟电路演化设计的多目标遗传算法,该方法利用非支配排序和适应值共享策略来提高搜索方向的空间均匀性,引入基于电路构造指令的编码方案来支持电路自动生成和提高电路演化的效率,并且该编码方案也同样适用于数字电路。利用协同演化的适应值评估策略来增强种群的学习能力,提高演化效率。实验结果表明,该方法可以设计出更实用、简单的模拟电路。     

A new hybrid method using evolutionary algorithms to train Fuzzy Cognitive Maps

A novel hybrid method based on evolutionary computation techniques is presented in this paper for training Fuzzy Cognitive Maps. Fuzzy Cognitive Maps is a soft computing technique for modeling complex systems, which combines the synergistic theories of neural networks and fuzzy logic. The methodology of developing Fuzzy Cognitive Maps relies on human expert experience and knowledge, but still exhibits weaknesses in utilization of learning methods and algorithmic background. For this purpose, we investigate a coupling of differential evolution algorithm and unsupervised Hebbian learning algorithm, using both the global search capabilities of Evolutionary strategies and the effectiveness of the nonlinear Hebbian learning rule. The use of differential evolution algorithm is related to the concept of evolution of a number of individuals from generation to generation and that of nonlinear Hebbian rule to the concept of adaptation to the environment by learning. The hybrid algorithm is introduced, presented and applied successfully in real-world problems, from chemical industry and medicine. Experimental results suggest that the hybrid strategy is capable to train FCM effectively leading the system to desired states and determining an appropriate weight matrix for each specific problem.     

A novel adaptive control strategy for decomposition-based multiobjective algorithm

Recently, evolutionary algorithm based on decomposition (MOEA/D) has been found to be very effective and efficient for solving complicated multiobjective optimization problems (MOPs). However, the selected differential evolution (DE) strategies and their parameter settings impact a lot on the performance of MOEA/D when tackling various kinds of MOPs. Therefore, in this paper, a novel adaptive control strategy is designed for a recently proposed MOEA/D with stable matching model, in which multiple DE strategies coupled with the parameter settings are adaptively conducted at different evolutionary stages and thus their advantages can be combined to further enhance the performance. By exploiting the historically successful experience, an execution probability is learned for each DE strategy to perform adaptive adjustment on the candidate solutions. The proposed adaptive strategies on operator selection and parameter settings are aimed at improving both of the convergence speed and population diversity, which are validated by our numerous experiments. When compared with several variants of MOEA/D such as MOEA/D, MOEA/D-DE, MOEA/D-DE+PSO, ENS-MOEA/D, MOEA/D-FRRMAB and MOEA/D-STM, our algorithm performs better on most of test problems.     

A comprehensive survey of fitness approximation in evolutionary computation

Evolutionary algorithms (EAs) have received increasing interests both in the academy and industry. One main difficulty in applying EAs to real-world applications is that EAs usually need a large number of fitness evaluations before a satisfying result can be obtained. However, fitness evaluations are not always straightforward in many real-world applications. Either an explicit fitness function does not exist, or the evaluation of the fitness is computationally very expensive. In both cases, it is necessary to estimate the fitness function by constructing an approximate model. In this paper, a comprehensive survey of the research on fitness approximation in evolutionary computation is presented. Main issues like approximation levels, approximate model management schemes, model construction techniques are reviewed. To conclude, open questions and interesting issues in the field are discussed.     

A method for regularization of evolutionary polynomial regression

While many applications require models that have no acceptable linear approximation, the simpler nonlinear models are defined by polynomials. The use of genetic algorithms to find polynomial models from data is known as evolutionary polynomial regression (EPR). This paper introduces evolutionary polynomial regression with regularization, an algorithm extending EPR with a regularization term to control polynomial complexity. The article also describes a set of experiences to compare both flavors of EPR against other methods including linear regression, regression trees and support vector regression. These experiments show that evolutionary polynomial regression with regularization is able to achieve better fitting and needs less computation time than plain EPR.     

A methodology for evolutionary product design

this paper describes a function-based approach for conceptual design support in the context of evolutionary product development. The main objective is to improve a designers productivity by the effective reuse of existing design information in design alternative identification, evaluation, and modification. An integrated evolutionary design methodology, EPD, is presented. The proposed methodology divides the whole process into three inter-related phases: information recovery, information management, and information reuse. The detailed steps in each phase are elaborated, and various techniques are employed to improve information reuse efficiency. A case study on commercial electrostatic air cleaner was used to illustrate the whole process of product evolutionary design. The proposed methodology will have a positive impact on the future development of the conceptual design support system.