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Geospatial cellular automata (Geo-CA) models have encountered challenges in computing efficiency and scalability when conducting large-scale land use change simulation applications. Parallel computing has proven to be effective to address these challenges. However, parallelization strategies for existing parallel Geo-CA models are always optimized for specific models and lack applicability to others. Besides, most parallel Geo-CA models focus on parallelizing land use change simulations, ignoring land use transition rule mining. Moreover, there is a lack of effective parallel strategies for demand-constrained land use change simulation on distributed heterogeneous architectures. This study proposes a parallel framework on hybrid parallel computing architectures applicable for raster-based Geo-CA models to enhance their computing efficiency and scalability while maintaining simulation accuracy. The framework provides parallelization strategies for both the land use transition rule mining for multiple land use types and the demand-constrained land use change simulation on distributed heterogeneous architectures. The framework was employed to parallelize two contemporary Geo-CA models, i.e., PLUS and MCCA. Experiments showed that the parallelized models achieved significant improvements in computing efficiency and scalability, confirming the effectiveness of the proposed framework for large-scale land use change simulation studies. [ABSTRACT FROM AUTHOR]

Background and Objectives: Quantum-dot Cellular Automata technology is a new method for digital circuits and systems designs. This method can be attractive for researchers due to its special features such as power consumption, high calculation speed and small dimensions. Methods: This paper tries to design a three-bits counter with minimum area and delay among the other circuits. As the circuit dimensions are reduced, the area and consequently, the delay are decreased, too. Therefore, this paper tries to design a three-bits counter with minimum dimensions and delay. The proposed counter contains 96 cells and is designed in three layers. It has the least area and delay compared to the priors. Results: The circuit simulation illustrates 0.08 µm2 of area occupation and one clock cycle delay. In comparison with the best previous design, which includes 110 cells, the cells number, area and delay are decreased by 12.72%, 27.27% and 33.33%, respectively. Also, the cost of the circuit has been improved by 54.32%. The power analysis of the design shows 13% reduction in the total energy dissipation of the circuit compared to the best prior work. The circuit reliability versus temperature variations has been simulated and the results represent suitable stability. The fault tolerance of the circuit which is occurred by the displacement faults represents normal operation of the circuit. Conclusion: As the counter is an element which is implemented in several digital systems, its area reduction causes the whole system area to be reduced. Also, the circuit delay has been decreased significantly which means that the circuit can be employed by high speed systems. [ABSTRACT FROM AUTHOR]

Water distribution networks (WDNs) are one of the largest infrastructures in society. Various methods for formulation and hydraulic analysis of water distribution networks, including numerical and non-numerical methods, have been previously proposed. Due to the complexity, the nonlinearity of the hydraulic equations of water distribution networks, and the need for multiple executions and uncertainties in parameters, solving the hydraulic model of water distribution networks has high time complexity. In this paper, a parallel computational architecture based on the concept of cellular automata is proposed to accelerate the numerical solution of the steady-state water distribution network model. Taylor series is proposed to solve hydraulic equations. The presented architecture was implemented as a parallel hardware platform on a field-programmable gate array. The performance of the proposed method was compared with EPANET software for networks with different complexities and topologies. The results show that the proposed parallel algorithm can accelerate the hydraulic analysis of regular water distribution networks up to 700 times and 250 times for small and large networks, respectively. • Proposed CA architectures to solve a system of non-linear equations on a fine-grain parallel architecture. • An efficient method to reduce computation time for hydraulic analysis of water networks. • The synthesizable hardware descriptions were generated through design automation. • Accelerate the hydraulic analysis of WDNs up to 700 times compared to EPANET, a well-known hydraulic analysis tool. [ABSTRACT FROM AUTHOR]

In this paper an algorithm for creating cave-like, user-guided layout is presented. In applications such as computer games, underground structures offer unique challenges and interesting space for player actions. Preparation of such areas can be time consuming and tiresome, especially during the design process, when many ideas are often scrapped. Presented approach aims at improving this process. Schematic input is used so the user can quickly define the general layout. Cave system is divided into levels and tiles - easily-parallelizable modules for the following method stages. Cellular automata are used to extend initial system sketch with interesting shapes while the diamond-square algorithm spreads the final terrain heights. Each stage uses the results of the previously performed operations as input, providing space for alterations. Input maps can be reused to obtain different variations of the same system. The final structure is represented as a 3D point cloud. Chosen representation supports multilevel systems and can be used either as a base for further algorithms, or as a final mesh. The presented approach can be easily incorporated into game design process, while visualizing initial layouts and speeding up preparation of unique, interesting and challenging game spaces for the players to traverse. [ABSTRACT FROM AUTHOR]

The theory and application of cellular automata (CA) for a stream cipher-based encryption principle are presented in this study. Certain fundamental transformations are developed based on CA theory regarding decentralized computation for modeling different system's behavior. The changes governing state transitions rely on simple evolution rules, which can easily be translated into functions using logic operators. A class of linear hybrid cellular automata (LHCA) based on rules 90 and 150 is used to implement these functions. Symmetric key systems theory is the foundation of the suggested algorithm. The algorithm functions use the proprieties provided by the LHCA evolution in order to convert plain text into cipher text and vice versa, in each case starting from the same initial state of the system and performing the same number of steps for each operation. Cellular automata's parallel information processing property, in addition to their regular and dynamical structure, makes hardware implementation of such schemes best suited for VLSI implementation. Testing of the proposed algorithm was performed by developing both software and hardware solutions. Hardware implementation of the presented cryptosystem was developed using VHDL hardware description language and a FPGA device (XILINX Spartan3E XC3S500E). Design and software simulations have been carried out using the C# programming language. [ABSTRACT FROM AUTHOR]

As an alternative to nanoelectronic devices, the quantum‐dot cellular automata (QCA) offer new opportunities to design high‐level algorithms and architectures. Using parallel processing, high speed, and low energy consumption, this emerging technology is very suitable and efficient for operational needs that require a large amount of computing and are often time consuming. In this paper, a new and optimal T‐latch design is introduced. The proposed latch structure has less occupied area and energy consumption than the existing implementation methods. In the proposed T‐latch the cell, area and energy consumption are reduced by 9.52%, 6.45%, and 19.67% compared to the best previous designs, respectively. Also, in this article, the T‐latch with reset and T‐latch with set/reset terminals are designed. Then, using the proposed T‐latch, various other latches are designed to ensure the correct operation of the designed T‐latch. Finally, to show that the proposed latch works properly in more complex circuits, they are used in the design of 1‐bit, 4‐bit, and n‐bit counters and the results of the simulations show the proper operation of the circuit. The proposed methods are simulated using the QCADesigner software and compared with other designs in terms of cell number, area, and energy consumption. [ABSTRACT FROM AUTHOR]

Quantum-dot cellular automata is a paradigm for classical computing which departs from the transistor paradigm and provides a system in which quantum phenomena may be studied. Here, the elementary computing device is a cell, a structure having multiple quantum dots and a few mobile charges. A specific operator-sum representation is developed for an exactly modeled double-dot, molecular cell within an environment of N similar neighboring molecules. While an operator-sum representation is not unique, a specific model can be determined by selecting a particular environmental basis. We select the environment's computational basis and calculate the specific and full set of 2N Kraus operators, which match exactly previous models of quantum decoherence in this system. Finally, the timescale for environmental interaction is characterized, enabling the reduction of the large set of Kraus operators to an approximate pair of Kraus operators, exact in the limit of large N. [ABSTRACT FROM AUTHOR]

Cellular Automata (CA) can be implemented by hardware and processed in parallel unlike the conventional algorithm based on chaotic function. In this paper, we propose a fast encryption algorithm for color image using (n, m, k)-programmable complemented maximum length CA((n, m, k)-PCMLCA). This algorithm improves the speed of shuffling pixel positions in the color image encryption system. The encryption process of the proposed image encryption system consists of a substitution step and a shuffling step. In the substitution step, we design the (n, m, k)-PCMLCA which can generate nonlinear sequences whose lengths are longer than the lengths of sequences generated by complemented maximum length CA (C-MLCA), and use it as the key sequence generator. In the shuffling step, we improve the encryption/decryption speed by raising the domain processing the image to the row/column level rather than the pixel unit and processing the block unit using 1-D MLCA. With the advantage of these CA, we can improve the speed of encryption/decryption. [ABSTRACT FROM AUTHOR]

The objective of this study was to explore the usefulness of virtual models and three-dimensional (3D) printing technologies for planning complex non-congenital cardiovascular surgery. Between July 2018 and December 2019, adult patients with different cardiovascular structural diseases were included in a clinical protocol to explore the usefulness of Standard Tessellation Language (STL)-based virtual models and 3D printing for prospectively planning surgery. A qualitative descriptive analysis from the surgeon's viewpoint was done based on the characteristics, advantages and usefulness of 3D models for guiding, planning and simulating the surgical procedures. A total of 14 custom 3D-printed heart and great vessel replicas with their corresponding 3D virtual models were created for preoperative surgical planning. Six of 14 models helped to redefine the surgical approach, 3 were useful to verify device delivery, while the rest did not change the surgical decision. In all open surgery cases, cardiac and vascular anatomy accuracy of virtual and physical 3D replicas was validated by direct visualisation of the organs during surgery. Printing was achieved through an external provider associated with the Hospital, who printed the final prototype in 5–7 days. Printed production cost was between 100 and 500 USD per model. In the current study, the selected 3D printed models presented different advantages (visual, tactile, and instrumental) over the traditional flat anatomical images when simulating and planning some complex types of surgery. Notwithstanding 3D printing advantages, STL-based virtual models were pre-printing useful tools when instrumentation on a physical replica was not required. [ABSTRACT FROM AUTHOR]

This paper introduces a cycle-based clustering technique using the cyclic spaces of reversible cellular automata (CAs). Traditionally, a cluster consists of close objects, which in the case of CAs necessarily means that the objects belong to the same cycle; that is, they are reachable from each other. Each of the cyclic spaces of a cellular automaton (CA) forms a unique cluster. This paper identifies CA properties based on "reachability" that make the clustering effective. To do that, we first figure out which CA rules contribute to maintaining the minimum intracluster distance. Our CA is then designed with such rules to ensure that a limited number of cycles exist in the configuration space. An iterative strategy is also introduced that can generate a desired number of clusters by merging objects of closely reachable clusters from a previous level in the present level using a unique auxiliary CA. Finally, the performance of our algorithm is measured using some standard benchmark validation indices and compared with existing well-known clustering techniques. It is found that our algorithm is at least on a par with the best algorithms existing today on the metric of these standard validation indices. [ABSTRACT FROM AUTHOR]

This paper develops a formal logic, named LCA, targeting modeling of one-dimensional binary cellular automata. We first develop the syntax of LCA, then give semantics to LCA in the domain of all binary strings. Then the elementary cellular automata and four-neighborhood binary cellular automata are shown as models of the logic. These instances point out that there are other models of LCA. Finally it is proved that any one-dimensional binary cellular automaton is a model of the proposed logic. [ABSTRACT FROM AUTHOR]

In contrast to many investigations of cellular automata with regard to their ability to accept inputs under certain time constraints, in this paper we are studying cellular automata with regard to their ability to generate strings in real time. Structural properties such as speedup results and closure properties are investigated. On the one hand, constructions for the closure under intersection, reversal and lengthpreserving homomorphism are presented, whereas on the other hand the nonclosure under union, complementation and arbitrary homomorphism are obtained. Finally, decidability questions such as emptiness, finiteness, equivalence, inclusion, regularity and context-freeness are addressed. [ABSTRACT FROM AUTHOR]

In our work, we proposed a parallel encryption scheme based on the state transition diagram of Maximum Length Cellular Automata (MLCA) to protect 3D images. Compared with the previous random mode decomposition (RMD) encryption scheme and DNA sequences and chaotic systems scheme, our scheme effectively reduces the time consumption, especially for the RME scheme, by up to 5 times. Meanwhile, leveraging MLCA's abundant rules, high parallelism, and straightforward hardware implementation, our encryption scheme exhibits flexible key selection, parallel processing capabilities, and easy hardware implementation. The results of key space analysis, differential attack analysis, and statistical analysis verify the high-security level achieved by our proposed parallel encryption scheme. • Encrypting the divided sub-aperture images in parallel improves the encryption speed. • Utilizing the state transition diagram of MLCA for encryption expands the key space. • It is also well-suited for encrypting large-size images in other domains. [ABSTRACT FROM AUTHOR]

Optimization for power is one of the most important design objectives in modern digital image processing applications. The DCT is considered to be one of the most essential techniques in image and video compression systems, and consequently a number of extensive works had been carried out by researchers on the power optimization. On the other hand, quantum-dot cellular automata (QCA) can present a novel opportunity for the design of highly parallel architectures and algorithms for improving the performance of image and video processing systems. Furthermore, it has considerable advantages in comparison with CMOS technology, such as extremely low power dissipation, high operating frequency, and a small size. Therefore, in this study, the authors propose a multiplier-less DCT architecture in QCA technology. The proposed design provides high circuit performance, very low power consumption, and very low dimension outperform to the existing conventional structures. The QCADesigner tool has been utilized for QCA circuit design and functional verification of all designs in this work. QCAPro, a very widespread power estimator tool, is applied to estimate the power dissipation of the proposed circuit. The suggested design has 53% improvement in terms of power over the conventional solution. The outcome of this work can clearly open up a new window of opportunity for low power image processing systems. [ABSTRACT FROM AUTHOR]

In this study, we detail the conditions that result in the generation of self-assembled quantum fortresses (QFs), in SiGe/Si. A QF consists of four quantum dots (QDs) clustered around a central square pit, one QD per side. This structure strongly resembles the proposed quantum cellular automata (QCA) unit cell—the basis for a computer architecture. We map the growth conditions (epilayer thickness and Ge concentration) under which self-assembly of strain-stabilized QFs and their precursors occur. Additionally, we characterize how QFs change in height, width, and internal size scales within this parameter space. From this information, we develop a phenomenological model for why QFs form based upon changes in lattice spacing. We then calculate how QFs of the observed shapes and sizes would function as QCAs based on a Hubbard-type Hamiltonian model. This analysis reveals that self-assembled QFs grown at 550 °C, a rate of 1 Å/s, a SiGe alloy composition of 37–40%, and a thickness of 15–35 nm could be used as QCAs. [ABSTRACT FROM AUTHOR]

The density classification task is one of the most adopted benchmark problems to study computational abilities of cellular automata. It consists in designing a cellular automaton that converges to uniform configurations according to the most frequent state in initial configurations. Earlier solutions for this task were designed by different methods and techniques; but since the symmetry and the number-conserving properties were introduced, many unknown solutions were found. In this work, we are interested in analyzing and understanding the general mechanisms by which cellular automata perform decentralized emergent computations to solve that task. For this purpose, we firstly propose a regular structure for the space of symmetric number-conserving cellular automata rules of radius r = 3. This allows us to outline their supported low-level computations. We show then that the proposed structure can significantly help to analyze the different solutions and, to make comparisons and conceptual connections among them. It also allows giving explanations about the computational strategies used by the currently best known solutions. Consequently, we could design new higher performing solutions - as compared to the currently best known ones - using cellular automata of radius r = 4. [ABSTRACT FROM AUTHOR]

In this work, we consider the cellular automata (CA) approach for modelling the climate change impact on water resources. This consists in: constructing a CA model that describes the water cycle dynamics taking into account physical terrain attributes and climatic constraints; coupling the CA model with climate projection scenarios for a considered region as input data; determining and analysing in output the variations of the underground, surface and evaporated water. We present these variations per time interval and per zone of influence. As an application, we consider simulation for a basin in northern Morocco using a simulation software we have designed in Java Object Oriented Programming. We consider cellular automata (CA) approach for modelling climate change impact on water resources. This consists in, first constructing a CA model that describes the water cycle dynamics taking into account physical terrain attributes and climatic constraints, then coupling the CA model with climate projection scenarios for a considered region as input data, and we determine and analyze in output the variations of the water resources (groundwater and surface water). We present these variations per time interval and per zone of influence. The approach application is for a basin in northern Morocco for which we use simulation software that we have designed in Java Object Oriented Programming. Digital terrain model, geological map and satellites image are used for input data. [ABSTRACT FROM AUTHOR]

An inverted ant cellular automata model called IACA-DI is proposed for the coordination of a swarm of robots performing the surveillance task. The swarm communicate indirectly through the repulsive pheromone, which is available as neighborhood information. The pheromone is deposited at each time step by each robot over its neighborhood. The new model started from a previous one named IACA. However, a discrete modeling of the pheromone diffusion is used in IACA-DI returning a sparser distribution of the robots over the environment. Next movement decisions are based on stochastic cellular automata rules that use the pheromone levels in the neighborhood to perform a probabilistic draw. While in IACA all the neighborhood cells participate in this draw, just a subgroup of them participate in the IACA-DI. It is formed by elite cells ? those with the lowest pheromone levels - and some random selected ones. Besides, the cell that keeps the current robot's direction receives an increment in its probability to be chosen, giving an inertial tendency to the robot motion. Simple simulations were performed enabling to refine parameters and to choose the better strategies. After this refinement, the resultant model was implemented in the simulation platform Webots™ aiming to evaluate IACA-DI with real-world robotic architecture in more realistic scenarios. IACA-DI is a new model for the coordination of robot swarms performing the surveillance task. It is based on cellular automata modeling and the swarm communicate indirectly through the repulsive pheromone deposited by the robots in the environment cells. Letters (a) and (b) show two snapshots from a simulation of a 3-robots swarm performing the surveillance task. The robots start at random positions in an environment composed by 7 rooms in (a). Thus, based on the IACA-DI decisions, they start to make steps to explore the environment aiming to cover all the rooms in a short interval of time. The trace of each robot after 100 time steps is shown in (b) by representing each individual trajectory with a different color. The behavior of each robot is managed by the IACA-DI model, which can be represented by the FSM with 4 states in (c). Different strategies and formulations were investigated for the two major states 'next position decision' and 'pheromone deposition'. The resultant IACA-DI model is analyzed here using simulations performed in Webots™ platform -as the snapshots shown in (a) and (b) -with real-world robotic architectures. [ABSTRACT FROM AUTHOR]

Cellular automata (CA) are dynamical systems with simple components but at the same time able to generate diverse and complex behaviour. In the present work we employ cellular automata to schedule programs over a multiprocessor system. The previously published CA-based scheduling models: SCAS-HP, SCAS-HP and SCAS-HP differ in the way they control the CA dynamical behaviour. Previous studies indicated that SCAS-HP tends to exhibit an inappropriate CA behaviour, which is mostly based on chaotic rules. Therefore, the parameters and are used to change the dynamical behaviour with the aim of improving the scheduling results. We investigate several instances of the scheduling problem which we split into two families of problems and by addressing each family separately to provide a more accurate evaluation of the models. The first family is formed by programs that solve linear equations by use of the Gaussian Elimination technique, while the second is comprised of artificial instances, which were randomly created in order to stress the scheduling performance of each model. The results indicate that both and can be used to adjust the dynamical behaviour in such models providing better scheduling results. [ABSTRACT FROM AUTHOR]

We discuss two ways in which information theory can be used to assess complexity in a system of interacting agents. In the first part, we adopt a global viewpoint and propose a characterization of complexity based on successive maximum entropy estimations of the probability density describing the system, thereby quantifying the respective role played by low and high orders of interaction. In the second part we reconsider the question from a local perspective, focussing on the statistical dependencies between neighbouring agents. These tools are tried on simple cellular automata in order to put them in perspective with other notions of complexity usually employed for such systems. We show that these approaches are hardly comparable, despite some overlap in simple cases. However this allows to interpret complexity in terms of interactions at work in a system (instead of making reference to any particular realization of this dynamics), and to shed some light on the role of initial conditions in complex systems. Clustering of the 88 non-equivalent Elementary Cellular Automata according to their position in the space of information processing features. Rules are coloured according to their Wolfram class. ECA in class I are shown in black, class II in red, chaotic automata (class III) in green and automata displaying complex behaviour (class IV) in blue. In spite of some important important differences, information features and Wolfram class are seen to overlap to a certain extent. [ABSTRACT FROM AUTHOR]

The gas dispersion simulation in complex urban environment posts challenges on consequence analysis. Though computational fluid dynamics (CFD) are general approaches to provide building-resolving estimates, the time consuming calculation and complex process of modeling limit their application for emergency response. In this paper, a cellular automata dispersion model is prompted to simulate continuous point release of propane in 3-D domain with ground obstructions. An artificial neural network is employed to calculate the temporal state transition of cellular automata. To provide data for the neural network to train, fire dynamic simulator (FDS) code is adopted to simulate 100 scenarios of propane release from a fixed position in pre-specific domain with different combinations of meteorological conditions and source parameters. A proportion of the simulation results is selected to train the artificial neural network with different transition rules derived from the advection-diffusion equation. The dispersion processes are eventually replicated with the proposed approach on the remaining scenarios that the artificial neural network has never encountered. Provided with detailed meteorological field data, the cellular automata model could calculate the gas dispersion process about 1.5 times faster than FDS. As to the model performance, in the long term evolution, decreases in model accuracy are observed due to the nature of cellular automata in explicit evolution and the unavailability of error compensation methods. The transition rule that takes source terms into consideration outperforms in estimating the concentration distributions. [ABSTRACT FROM AUTHOR]

Highlights • A 3D CAFE fracture model for heterogeneous materials is described. • A hybrid MPI/Fortran coarray programming for HPC is demonstrated. • Strong scaling up to 7000 Cray XC30 cores is shown. Abstract A 3D multi-scale cellular automata finite element (CAFE) framework for modelling fracture in heterogeneous materials is described. The framework is implemented in a hybrid MPI/Fortran coarray code for efficient parallel execution on HPC platforms. Two open source BSD licensed libraries developed by the authors in modern Fortran were used: CGPACK, implementing cellular automata (CA) using Fortran coarrays, and ParaFEM, implementing finite elements (FE) using MPI. The framework implements a two-way concurrent hierarchical information exchange between the structural level (FE) and the microstructure (CA). MPI to coarrays interface and data structures are described. The CAFE framework is used to predict transgranular cleavage propagation in a polycrystalline iron round bar under tension. Novel results enabled by this CAFE framework include simulation of progressive cleavage propagation through individual grains and across grain boundaries, and emergence of a macro-crack from merging of cracks on preferentially oriented cleavage planes in individual crystals. Nearly ideal strong scaling up to at least tens of thousands of cores was demonstrated by CGPACK and by ParaFEM in isolation in prior work on Cray XE6. Cray XC30 and XC40 platforms and CrayPAT profiling were used in this work. Initially the strong scaling limit of hybrid CGPACK/ParaFEM CAFE model was 2000 cores. After replacing all-to-all communication patterns with the nearest neighbour algorithms the strong scaling limit on Cray XC30 was increased to 7000 cores. TAU profiling on non-Cray systems identified deficiencies in Intel Fortran 16 optimisation of remote coarray operations. Finally, coarray synchronisation challenges and opportunities for thread parallelisation in CA are discussed. [ABSTRACT FROM AUTHOR]

Presents information on a study that examined the dynamic behavior of quantum cellular automata, arrays of artificial quantum-dot cells that can be used to perform useful computations. Incoherent cell-cell dynamics; Coherent full-basis cell dynamics; Dynamics of the semi-finite wire.

A new Multi-Stage Multi-Secret Image Sharing (MSMSIS) scheme, based on polynomial sharing and cellular automata, is proposed in this paper. The proposed scheme shares multiple secret images among a number of players. The shares and the authentication strings, produced by a cryptographic hash function, are then embedded in cover images by an XOR-based operation in such a way that visual and statistical quality of covers are preserved as much as possible. A particular type of cellular automata is used to guarantee that the secrets are only recovered according to a pre-specified order. The scheme is multi-use, since some parameters are distributed only once and used multiple times. The scheme is verifiable as well, because a cryptographic hash function is used in each stage for each secret image separately. Generality of our scheme also implies that it can be applied on a heterogeneous set of different secret formats, where each secret has its own access structure. Based on our experiments, the PSNR of the proposed method is improved almost 11 percent compared to the average PSNR of the previous similar schemes. [ABSTRACT FROM AUTHOR]

In multimedia communication, significance of the images for data representation is noteworthy. In this context, secure transmission of images over open channel has become a challenging task. Creation of different strategies in improving the secure image transmission always has a demand. The proposed work suggests an RGB image encryption with the confluence of attractors and hardware triggered key image in which confusion and diffusion were accomplished by Lorenz, Lü and Cellular Automata attractors. The uniqueness of proposed encryption scheme is a key image generation module through cascaded Ring Oscillator circuit which creates M × N key image for diffusion of pixels. Facilitating the authenticated networked access to key image generation hardware enables the secure server-client architecture for a variety of secure image transfer applications. The proposed approach is a hardware - software codesign which possesses a good keyspace, improved key sensitivity and satisfies the various statistical parameters thus offering substantial resistance to differential, occlusion and chosen plaintext attacks on RGB images. [ABSTRACT FROM AUTHOR]

Cellular automata (CAs), such as the best-known Game of Life (GL), has been studied extensively as theoretical models for massively parallel computation. Implementation of CAs in hardware may not only establish a fully parallel architecture, but also facilitate the inclusion of bio-inspired mechanisms, e.g., self-reproduction and self-organization, into computational processes. Previous implementations of CAs usually depend on combinational logic circuits, in which a clock signal must be distributed in parallel to all modules each simulating a CA's cell. This paper proposes an effective scheme for constructing the GL via a delayinsensitive (DI) circuit, a special type of asynchronous circuits whose correctness of operation is not affected by arbitrary delays in modules or interconnection lines. In order to simulate the synchronous transitions of all GL's cells, the scheme adopts a natural handshaking mechanism which enables all modules that are interconnected uniformly within the circuit to operate in lockstep at local scale. This actually eliminates the distribution of a clock signal and allows a scalable structure for the DIcircuit. Moreover, the Dl-circuit is composed by simple elements without extra elements used for arbitrating unexpected inputs, which may benefit the implementation of the circuit in RSFQ, or other post-CMOS technologies. [ABSTRACT FROM AUTHOR]

At signalized intersection areas, bicycle traffic presents a dispersion feature which may influence the movements of vehicles during peak period. The primary objective of this study is to simulate the dispersion effect in through-movement bicycle traffic at intersection areas and evaluate its influence on through-movement traffic. A cellular automata (CA) model is developed and validated to simulate the operations of through-movement bicycle traffic departing from two types of intersection approaches. Simulation results show that bicycles benefit from the dispersion effect when they depart from the approach with an exclusive right-turn vehicle lane. But when bicycles travel from the approach with a shared right-turn and through vehicle lane, the dispersion effect will result in friction interference and block interference on through-movement vehicles. Bicycle interferences reduce the vehicle speed and increase the delay of through-movement vehicles. The policy implications in regard to the dispersion effect from two types of approaches are discussed to improve the performance of through-movement traffic operations at signalized intersections. [ABSTRACT FROM AUTHOR]

Quantum-dot cellular automata (QCA) is a promising emerging nanotechnology that has been attracting considerable attention due to its small feature size, ultra-low power consuming, and high clock frequency. Therefore, there have been many efforts to design computational units based on this technology. Despite these advantages of the QCA-based nanotechnologies, their implementation is susceptible to a high error rate. On the other hand, using the reversible computing leads to zero bit erasures and no energy dissipation. As the reversible computation does not lose information, the fault detection happens with a high probability. In this paper, first we propose a fault-tolerant control unit using reversible gates which improves on the previous design. The proposed design is then synthesized to the QCA technology and is simulated by the QCADesigner tool. Evaluation results indicate the performance of the proposed approach. [ABSTRACT FROM AUTHOR]

The reaction-diffusion (RD) models describe the change in the behavior of one or more chemical substances through space and time. The RD interaction can create waves of chemical concentration when the chemical systems used are far from equilibrium. The velocity and direction of those waves can be controlled and altered using excitable media or inhibitors. In particular, excitable media are spatially distributed systems characterized by their ability to propagate signals undamped over long distances, while inhibitors are used to reduce the propagation of those signals. The behavior of chemical oscillators are based on such media. The concept of this article is the proposal of a Cellular Automaton (CA) model which exploits the wave propagation characteristics on an excitable medium using inhibitors to create a switching element which is capable of distinguishing two binary states and present a form of amplification, like a basic transistor. In such a sense an unconventional chemical made device with properties similar to the conventional basic element of todays electronics, namely CMOS transistor is conceived. Furthermore, and in order to properly explore the potential of the proposed device, we design a combination of two of those transistors to prove that they can reproduce Boolean algebra by creating two of the most well known and important component, i.e. the inverter NOT logic gate and the universal logic gate NAND. [ABSTRACT FROM AUTHOR]

When fish that have been trained to school toward a blue or a yellow target are mixed together with only a small difference in population size they rarely change their target preference. When untrained fish are introduced, however, often the whole mixed population will school toward the target preferred by the initial majority. This is a macroscopic, biological example of the "majority identification problem" studied in the cellular automaton literature. By closely adhering to the empirical conditions of these experiments we have developed a "directed majority" cellular automaton that: (a) solves the identification problem well even for small initial majorities; (b) explains why untrained fish help persuade minority fish to join the majority; and (c) predicts that untrained fish achieve this feat by collaborating in spatially structured cliques that might be observable in experiments with larger populations. The directed majority automaton provides insight into the consensus forming process and holds promise for being able to predict when systems (similar to the fish) will successfully perform majority identification. [ABSTRACT FROM AUTHOR]

Quantum-dot cellular automata (QCA) has come out as one of the potential computational structures for the emerging nanocomputing systems. It has a large capacity in the development of circuits with high space density and dissipation of low heat and allows faster computers to develop with lower power consumption. The QCA is a new appliance to realize nanolevel digital devices and study and analyze their various parameters. It is also a potential technology for low force and high-density memory plans. Large memory designs in QCA show unique features because of their architectural structure. In QCA-based architectures, memory must be maintained in motion, i.e., the memory state has to be continuously moved through a set of QCA cells. These architectures have different features, such as the number of bits stored in a loop, access type (serial or parallel) and cell arrangement for the memory bank. However, the decisive features of the QCA memory cell design are the number of cells, to put off the use of energy. Although the review and study of the QCA-based memories are very important, there is no complete and systematic literature review about the systematical analyses of the state of the mechanisms in this field. Therefore, there are five main types to provide systematic reviews about the QCA-based memories; including read only memory (ROM), register, flip-flop, content addressable memory (CAM) and random access memory (RAM). Also, it has provided the advantages and disadvantages of the reviewed mechanisms and their important challenges so that some interesting lines for any coming research are provided. [ABSTRACT FROM AUTHOR]

Grind-hardening process is a hybrid process for the simultaneous finishing and heat treatment of the workpiece material. Several studies have been presented for the simulation of the process, using either analytical or finite element-based models. In the present paper, the cellular automata method is used for simulating the metallurgical changes in the workpiece material. The method is coupled with a finite element model for the macro-modelling of the process, allowing the prediction of the microstructure of the material as a function of the macro-process parameters. [ABSTRACT FROM AUTHOR]

Being unavailable in the literature for the past few recent decades, the cellular automata formulations of some algorithms for sorting character and string arrays are considered here. A cellular automaton multiplying two integers written in a numeral system with an arbitrary basis is proposed for the first time. The algorithm is based on the Atrubin parallel multiplication scheme for a systolic array of processors and requires four components (registers) instead of five. [ABSTRACT FROM AUTHOR]

Urban cellular automata (CA) models propagate and accumulate errors during the modeling process due to the model structure or stochastic processes involved. It is feasible to assimilate real-time observations into an urban CA model to reduce model uncertainties. However, the assimilation performance is sensitive to the spatio-temporal units in the assimilation algorithm, that is, spatial block size and window length (temporal interval). In this study, we coupled an assimilation model, an ensemble Kalman filter (EnKF) and a Logistic-CA model to simulate the urban dynamic in Beijing over a period of two decades. Our results indicate that the coupled EnKF-CA model outperforms the CA-alone counterpart by about 10% in terms of the figure of merit, which reflects the agreement of modeled pixels. We also find that the assimilation performance using a finer block (1 km) is better than that using a coarser block (5 km and 10 km) because of the better depiction of spatial heterogeneity using a finer block. Moreover, the improvement of intermediate outputs using the coupled EnKF-CA model is effective for a certain period (e.g. 5 years). This implies that a high-frequency assimilation may not significantly improve the model performance. The sensitivity analyses of spatio-temporal assimilation in the EnKF-CA model provide a better understanding of the assimilation mechanism that couples with land-use change models. [ABSTRACT FROM PUBLISHER]

Considering the process of pedestrian evacuation as pedestrian walking freely from current position to exit and queuing at the exit, estimated evacuation time model for single pedestrian is established. Based on estimated evacuation time and shortest distance, pedestrian exit choice model is established considering pedestrian preference. Pedestrian exit choice model is added into pedestrian simulation model which is built based on cellular automata. Pedestrian evacuation behavior in multi-exits case is simulated. The simulations indicate that pedestrian evacuation model built in our work describes the pedestrian evacuation behavior well. [ABSTRACT FROM AUTHOR]

Cellular automata (CA) models are of interest to several scientific areas, and there is a growing interest in exploring large systems which would need high performance computing. In this work a CA implementation is presented which performs well in five different NVIDIA GPU architectures, from Tesla to Maxwell, simulating systems with up to a billion cells. Using the game of life (GoL) and a more complex variation of GoL as examples, a performance of 5.58e6 evaluated cells/s is achieved. The two optimizations most often used in previous studies are the use of shared memory and Multicell algorithms. Here, these optimizations do not improve performance in Fermi or newer architectures. The GoL CA code running in an NVIDIA Titan X obtained a speedup of up to $$\sim $$ 85 x and up to $$\sim $$ 230 x for a more complex CA, compared to an optimized serial CPU implementation. Finally, the efficiency of each GPU is analyzed in terms of cell performance/transistors and cell performance/bandwidth showing how the architectures improved for this particular problem. [ABSTRACT FROM AUTHOR]

Interactive segmentation of images has become an integral part of image processing applications. Several graph based segmentation techniques have been developed, which depend upon global minimization of the energy cost function. An adequate scheme of interactive segmentation still needs a skilled initialization of regions with user-defined seeds pixels distributed over the entire image. We propose an iterative segmentation technique based on Cellular Automaton which focuses to reduce the user efforts required to provide initialization. The existing algorithms based on Cellular Automaton only use local smoothness term in label propagation making them highly sensitive to user-defined seeds pixels. To reduce the sensitivity towards initial user definition of regions, global constraints are introduced along with local information to propagate labels. The results obtained are comparable to the state-of-the-art interactive segmentation techniques on a standard dataset. [ABSTRACT FROM AUTHOR]

Quantum dot cellular automata (QCA) is an upcoming nano-technology for its high speed and low power operation in the field of nano-science and nano-electronics. As QCA overcomes the drawbacks of CMOS technology, it has appreciable applications in quantum computation. There are thousands of designs of different logical circuits using QCA but there is no hazard free design of the logical circuits in the field of QCA. In a circuit, hazards always produce an unpredictable output which can be avoided. In this paper, both hazardous and hazard-free asynchronous sequential circuits are considered and compared in terms of kink energy. It is shown that hazard free asynchronous circuit performs better in terms of kink energy in the field of QCA. [ABSTRACT FROM AUTHOR]

For nano scale logic circuit, device area and power consumption are the major concerns. In this paper, the design of an optimized SISO shift register is explored based on quantum-dot cellular automata (QCA) device. The design is achieved in a single layer. To design the shift register circuit, a new QCA D flip-flop has been proposed. These new D flip-flop has minimum cell count and lower device area over existing designs. The proposed shift register also outperforms the existing designs by reducing cell count and area. The power consumption by the proposed design is carried out that shows the low energy consumption nature of the circuit. Logic gate, QCA cell and device density have been considered to evaluate the circuit. Simulation timing diagram and truth table of the proposed circuits are compared which shows that all the designs are functioning efficiently. Stability under thermal randomness for all the designs are analyzed which shows the steadiness of the designs. The impacts of control input, i.e., clock on the designs are explored. Besides the defects in proposed QCA layouts are also identified and excelled for fault free implementation. [ABSTRACT FROM AUTHOR]

A major conceptual step forward in understanding the logical architecture of living systems was advanced by von Neumann with his universal constructor, a physical device capable of self-reproduction. A necessary condition for a universal constructor to exist is that the laws of physics permit physical universality, such that any transformation (consistent with the laws of physics and availability of resources) can be caused to occur. While physical universality has been demonstrated in simple cellular automata models, so far these have not displayed a requisite feature of life--namely open-ended evolution--the explanation of which was also a prime motivator in von Neumann's formulation of a universal constructor. Current examples of physical universality rely on reversible dynamical laws, whereas it is well-known that living processes are dissipative. Here we show that physical universality and open-ended dynamics should both be possible in irreversible dynamical systems if one entertains the possibility of state-dependent laws. We demonstrate with simple toy models how the accessibility of state space can yield open-ended trajectories, defined as trajectories that do not repeat within the expected Poincaré recurrence time and are not reproducible by an isolated system. We discuss implications for physical universality, or an approximation to it, as a foundational framework for developing a physics for life. [ABSTRACT FROM AUTHOR]