Specification methods for material-handling control algorithms in flexible manufacturing systems

Good methods are needed to specify, test, and debug material-handling control logic. This article surveys a number of representative methods for defining and describing control algorithms for programmable material-handling equipment used in flexible manufacturing systems. The methods are evaluated with regard to their suitability for communication between people and as bases for interfaces to automatic program generators. It is concluded that no single method is entirely satisfactory. Three methods (position diagrams, function block diagrams, and operation networks) have potential to be combined into an effective hybrid approach that minimizes the need for the user to switch between various conceptual models.     

Evolving digital circuits using hybrid particle swarm optimization and differential evolution

This paper presents the evolution of combinational logic circuits by a new hybrid algorithm known as the Differential Evolution Particle Swarm Optimization (DEPSO), formulated from the concepts of a modified particle swarm and differential evolution. The particle swarm in the hybrid algorithm is represented by a discrete 3-integer approach. A hybrid multi-objective fitness function is coined to achieve two goals for the evolution of circuits. The first goal is to evolve combinational logic circuits with 100% functionality, called the feasible circuits. The second goal is to minimize the number of logic gates needed to realize the feasible circuits. In addition, the paper presents modifications to enhance performance and robustness of particle swarm and evolutionary techniques for discrete optimization problems. Comparison of the performance of the hybrid algorithm to the conventional Karnaugh map and evolvable hardware techniques such as genetic algorithm, modified particle swarm, and differential evolution are presented on a number of case studies. Results show that feasible circuits are always achieved by the DEPSO algorithm unlike with other algorithms and the percentage of best solutions (minimal logic gates) is higher.     

Ferroelectric Hybrid Plasmonic Waveguide for All-Optical Logic Gate Applications

A ferroelectric hybrid plasmonic waveguide, made of a polycrystal lithium niobate waveguide separated from a gold film by a silicon dioxide isolation layer, is fabricated by use of laser molecular beam epitaxy growth, electron beam evaporation, and focused ion beam etching. Strong subwavelength mode confinement and excellent long-range propagation are achieved simultaneously for the hybrid plasmonic mode. An all-optical logic OR gate is also realized based on the ferroelectric hybrid plasmonic waveguide. This may provide a way for the study of all-optical logic gates and integrated photonic circuits.     

Comparing the performance of multilayer perceptrons networks and neuro-fuzzy systems for on-line inference of <Emphasis Type="Italic">Bacillus megaterium</Emphasis> cellular concentrations

Penicillin G acylase (PGA) is one of the most important enzymes for the pharmaceutical industry. Bacillus megaterium has the advantage of producing extra-cellular PGA. This work compares two neural networks (NNs) architectures for on-line inference of B. megaterium cell mass in an aerated stirred tank bioreactor, during the production of PGA. Nowadays, intelligent computing tools such as artificial NNs and fuzzy logic are commonly applied for state inference and modeling of bioreactors. Combining these two approaches in hybrid, neuro-fuzzy systems, may be advantageous. Our results indicate that a neuro-fuzzy inference system showed a better performance to infer cell concentrations, when compared to multilayer perceptrons networks.     

The application of yeast hybrid systems in protein interaction analysis

Yeast hybrid systems have been widely used due to their convenience and low cost. Based on these systems, many methods have been developed to analyze protein–protein, protein–DNA and protein–RNA interactions. In this paper, we are reviewing these different yeast hybrid systems. According to the number of hybrid proteins, yeast hybrid systems can be divided into three categories, yeast one-hybrid, yeast two-hybrid and yeast three-hybrid systems. Alternatively, yeast hybrid systems can be categorized according to the subcellular localization of the protein interaction process in the cell into nuclear protein–protein interactions, cytosol protein–protein interactions and membrane protein–protein interactions. Throughout the review, we focus on the progress and limitations of each yeast hybrid system over the recent years.     

Dual Logic and Cerebral Coordinates for Reciprocal Interaction in Eye Contact

In order to scientifically study the human brain’s response to face-to-face social interaction, the scientific method itself needs to be reconsidered so that both quantitative observation and symbolic reasoning can be adapted to the situation where the observer is also observed. In light of the recent development of dyadic fMRI which can directly observe dyadic brain interacting in one MRI scanner, this paper aims to establish a new form of logic, dual logic, which provides a theoretical platform for deductive reasoning in a complementary dual system with emergence mechanism. Applying the dual logic in the dfMRI experimental design and data analysis, the exogenous and endogenous dual systems in the BOLD responses can be identified; the non-reciprocal responses in the dual system can be suppressed; a cerebral coordinate for reciprocal interaction can be generated. Elucidated by dual logic deductions, the cerebral coordinate for reciprocal interaction suggests: the exogenous and endogenous systems consist of the empathy network and the mentalization network respectively; the default-mode network emerges from the resting state to activation in the endogenous system during reciprocal interaction; the cingulate plays an essential role in the emergence from the exogenous system to the endogenous system. Overall, the dual logic deductions are supported by the dfMRI experimental results and are consistent with current literature. Both the theoretical framework and experimental method set the stage to formally apply the scientific method in studying complex social interaction.     

Hybrid peptide-polyketide natural products: biosynthesis and prospects toward engineering novel molecules

The structural and catalytic similarities between modular nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) inspired us to search for hybrid NRPS-PKS systems. By examining the biochemical and genetic data known to date for the biosynthesis of hybrid peptide-polyketide natural products, we show (1) that the same catalytic sites are conserved between the hybrid NRPS-PKS and normal NRPS or PKS systems, although the ketoacyl synthase domain in NRPS/PKS hybrids is unique, and (2) that specific interpolypeptide linkers exist at both the C- and N-termini of the NRPS and PKS proteins, which presumably play a critical role in facilitating the transfer of the growing peptide or polyketide intermediate between NRPS and PKS modules in hybrid NRPS-PKS systems. These findings provide new insights for intermodular communications in hybrid NRPS-PKS systems and should now be taken into consideration in engineering hybrid peptide-polyketide biosynthetic pathways for making novel "unnatural" natural products.     

Hybrid control strategies for a five-finger robotic hand

This paper presents a hybrid controller of soft control techniques, adaptive neuro-fuzzy inference system (ANFIS) and fuzzy logic (FL), and hard control technique, proportional-derivative (PD), for a five-finger robotic hand with 14-degrees-of-freedom (DoF). The ANFIS is used for inverse kinematics of three-link fingers and FL is used for tuning the PD parameters with 2 input layers (error and error rate) using 7 triangular membership functions and 49 fuzzy logic rules. Simulation results with the hybrid of FL-tuned PD controller exhibit superior performance compared to PD, PID and FL controllers alone.     

A Novel Bio-Sensor Based on DNA Strand Displacement

DNA strand displacement technology performs well in sensing and programming DNA segments. In this work, we construct DNA molecular systems based on DNA strand displacement performing computation of logic gates. Specifically, a class of so-called “DNA neurons” are achieved, in which a “smart” way inspired by biological neurons encoding information is developed to encode and deliver information using DNA molecules. The “DNA neuron” is bistable, that is, it can sense DNA molecules as input signals, and release “negative” or “positive” signals DNA molecules. We design intelligent DNA molecular systems that are constructed by cascading some particularly organized “DNA neurons”, which could perform logic computation, including AND, OR, XOR logic gates, automatically. Both simulation results using visual DSD (DNA strand displacement) software and experimental results are obtained, which shows that the proposed systems can detect DNA signals with high sensitivity and accretion; moreover, the systems can process input signals automatically with complex nonlinear logic. The method proposed in this work may provide a new way to construct a sensitive molecular signal detection system with neurons spiking behavior in vitro, and can be used to develop intelligent molecular processing systems in vivo.     

A biochemical logic gate using an enzyme and its inhibitor. 1. The inhibitor as switching element

Molecular-scale logic systems will allow for further miniaturization of information processing assemblies and contribute to a better understanding of brain function. Of much interest are the pertinent biological systems, some of the basic components of which are biomolecular switching elements and enzyme-based logic gates.In this series of accounts, results of investigations are presented on the implementation of an enzyme/inhibitor logic gate operating under the rules of Boolean algebra. In this report (part 1 of the series), consideration is given to the experimental conditions-particularly the irradiation mode-that affect the performance of proflavine as inhibitor of alpha-chymotrypsin. Also, assessments are made on the reversibility of the process involved and the long-term stability of the system. Moreover, using a theoretical conformational analysis of proflavine and its reduction products, detailed features were established regarding their three-dimensional structure, partial charge distribution, and hydrophobicity. Accordingly, an understanding was reached as to the factors affecting the interaction between these compounds and the enzyme. In part 2 of this series, the actual implementation of an AND logic gate will be presented. This gate involves proflavine and a chemically derivatized alpha-chymotrypsin, and its operation relies on the conclusions reached in this report regarding the optimal mode for controlling the inhibitory activity of proflavine.     

An introduction to hybrid computers and their application to optimization problems

The author, who is Secretary of the Analog Section of the British Computer Society, describes the way in which some of the logic components of a parallel logic analog computer function, and goes on to discuss the use of such a computer in optimization problems, as for instance in finding the best estimates of the parameters on compartmentation analysis of isotopic tracer experiments. The increased power which is gained when an analog computer is coupled to (hybridized with) a general purpose digital computer is then discussed, as shown for example in the increased speed of random-search optimization techniques when an analog computer is used to integrate the differential equations, or the improvement in steepest ascent methods when the parallel logic can be used to keep the hill-climb path continuously on the line of steepest ascent. Finally, the use of a hybrid computer in solving partial differential equations is briefly outlined.     

The Bio-Logic and machinery of plant morphogenesis

Morphogenesis (the development of organic form) requires signal-trafficking and cross-talking across all levels of organization to coordinate the operation of metabolic and genomic networked systems. Many biologists are currently converging on the pictorial conventions of computer scientists to render biological signaling as logic circuits supervising the operation of one or more signal-activated metabolic or gene networks. This approach can redact and simplify complex morphogenetic phenomena and allows for their aggregation into diagrams of larger, more "global" networked systems. This conceptualization is discussed in terms of how logic circuits and signal-activated subsystems work, and it is illustrated for examples of increasingly more complex morphogenetic phenomena, e.g., auxin-mediated cell expansion, entry into the mitotic cell cycle phases, and polar/lateral intercellular auxin transport. For each of these phenomena, a posited circuit/subsystem diagram draws rapid attention to missing components, either in the logic circuit or in the subsystem it supervises. These components must be identified experimentally if each of these basic phenomena is to be fully understood. Importantly, the power of the circuit/subsystem approach to modeling developmental phenomena resides not in its pictorial appeal but in the mathematical tools that are sufficiently strong to reveal and quantify the synergistics of networked systems and thus foster a better understanding of morphogenesis.     

Deoxyribozyme-based three-input logic gates and construction of a molecular full adder

We have developed an array of seven deoxyribozyme-based molecular logic gates that behaves as a full adder in a single solution, with three oligonucleotides as inputs and two independent fluorogenic cleavage reactions as carry and sum outputs. The sum output consisted of four new deoxyribozyme-based logic gates: an ANDAND gate and three ANDNOTANDNOT gates. These gates required the design of a generic three-input deoxyribozyme-based logic gate that can use any three-way combination of activating or inactivating inputs. This generic gate design utilizes an additional inverting element that hybridizes to convert YES logic into NOT logic and vice versa. The system represents the first solution-phase, single test tube, enzymatic full adder and shows the complexity of control over molecular scale events that can be achieved with deoxyribozyme-based logic gates. Similar systems could be applied to control autonomous therapeutic and diagnostic devices.     

Hybrid seed production and the challenge of propagating male-sterile plants

The introduction of hybrid crop varieties has enabled spectacular increases in productivity owing to hybrid vigor and increased uniformity. To produce hybrid seeds, a pollination control system is required to prevent unwanted self-pollination. In crop species with hermaphrodite flowers, this can be a major challenge. Over the past decade, new pollination control systems have been developed with the aid of genetic engineering, mainly based on the generation of nuclear-encoded male sterility. The successful application of these systems for large-scale hybrid seed production depends on whether the male-sterile female parent line can be multiplied efficiently and economically. In spite of its relevance, the propagation of the male-sterile line has often been overlooked in the development of pollination control systems.     

Developing a Hybrid Programmable Logic Controller Platform for a Flexible Manufacturing System

In this article, we present the design and implementation of a flexible manufacturing system (FMS) control platform based on a programmable logic controller (PLC) and a personal computer (PC)-based visual man-machine interface (MMI) and data acquisition (DAS) unit. The key aspect of an FMS is its flexibility to adapt to changes in a demanding process operation. The PLC provides feasible solutions to FMS applications, using PC-based MMI/DAS, whereby PLCs are optimized for executing rapid sequential control strategies. PCs running MMI/DAS front-ends make intuitive operation interfaces, full of powerful graphics and reporting tools. Information from the PC can be distributed through a company's local area network or web using client-server technologies. Currently, with the convergence of underlying microprocessor technology and software programming techniques, many users find that PLCs provide a cost-effective solution to real-time control in small- to medium-sized process plants, especially when combined with supervisory PCs using hybrid systems. The major work of this article demonstrates that PLCs are responsive to rapid and repetitious control tasks, using PCs that present the flow of information automation and accept operator instructions, thereby providing the user a tool to modify and monitor the process as the requirements change.     

From complexation to computation: Recent progress in molecular logic

The new thrusts in molecular logic are gathered together in this short review, while paying attention to the seeds from which these developments have arisen. The original demonstration of a few basic logic operations has now been extended to cover many of the one- and two-input varieties and even some of the three-input types. Many kinds of inputs and outputs have emerged, including various chemical species and some physical properties. The latter can include heat, light and, arguably, polarity. Reconfigurable logic has grown up to include a range of examples. Even superposable logic has proved possible with molecular systems. Numerical processors have flowered in recent years with several diverse approaches being revealed in recent years. Photochemical concepts such as photoinduced electron transfer (PET), internal charge transfer (ICT) and electronic energy transfer (EET) can be discerned among the designs in the field.     

Unraveling Charge Separation and Transport Mechanisms in Aqueous‐Processed Polymer/CdTe Nanocrystal Hybrid Solar Cells

Recently great progress has been achieved in highly effective hybrid solar cells fabricated using aqueous materials. The state‐of‐the‐art energy conversion efficiency has been close to 5% with high photocurrent. However, charge separation and transport mechanism in the aqueous‐processed hybrid solar cells are rarely reported and are usually assumed to be similar to oil‐phase processed systems; that is, self‐assembly polymers are mainly responsible for charge separation and carrier transport. To date, this assumption has prohibited further improvement of the conversion efficiency in aqueous‐processed hybrid systems by adopting any appropriate technique routes. Here, ultrafast carrier dynamics in these hybrid solar cells consisting of poly(p‐phenylenevinylene) (PPV)‐based aqueous polymers and water‐solution CdTe nanocrystals (NCs) are investigated in detail. Self‐charge separation in grown CdTe NC partly capped CdS shell layers after anneal treatment is unambiguously identified. Different from their oil‐soluble counterparts, these core/shell nanocrystals do not have the restrictions of quantum confinement and surface ligands, form effective charge transport networks, and play a dominant role in the charge separation and carrier transport processes. These findings provide a greater understanding on the fundamental photophysics in aqueous‐processed hybrid systems.     

Congruence between independent character systems across a hybrid zone: patterns in geographic space

The hybrid zone between eastern and western grass snakes, which has been independently hypothesized to be due to secondary contact, is investigated using univariate and multivariate analysis of a large number of independent, quantitative characters. Investigation of the patterns of geographic variation show that 5 out of 6 character systems show a congruent pattern of “stepped clinal” change across the zone. Insofar as this case is concerned, secondary contact ‘hybrid’ zones are associated with concordant changes in many character systems and “speciation” involves the origin of a large number of small differences in most character systems rather than the major reorganisation of a single system.     

Relating hybrid advantage and genome replacement in unisexual salamanders

Unisexual vertebrates are model systems for understanding the evolution of sex. Many predominantly clonal lineages allow occasional genetic recombination, which may be sufficient to avoid the accumulation of deleterious mutations and parasites. Introgression of paternal DNA into an all-female lineage represents a one-way flow of genetic material. Over many generations, this could result in complete replacement of the unisexual genomes by those of the donor species. The process of genome replacement may be counteracted by contemporary dispersal or by positive selection on hybrid nuclear genomes in ecotones. I present a conceptual model that relates nuclear genome replacement, positive selection on hybrids and biogeography in unisexual systems. I execute an individual-based simulation of the fate of hybrid genotypes in contact with a single host species. I parameterize these models for unisexual salamanders in the Ambystoma genus, for which the frequency of genome replacement has been a source of ongoing debate. I find that, if genome replacement occurs at a rate greater than 1/10,000 in Ambystoma, then there must be compensating positive selection in order to maintain observed levels of hybrid nuclei. Future researchers studying unisexual systems may use this framework as a guide to evaluating the hybrid superiority hypothesis.     

Hybrid Photoelectrochemical Water Splitting Systems: From Interface Design to System Assembly

Photoelectrochemical (PEC) water splitting has attracted increasing attention due to its potential to mitigate energy and environmental issues. Hybrid PEC systems containing semiconductor photosensitizers and molecular catalysts are reported to be highly active and stable for water splitting with great potential for facilitating clean fuels production. In this review, following a showcasing of the fundamental details of hybrid PEC systems for water splitting, semiconductor/molecular catalyst interface designs are highlighted, with a focus on interfacial physicochemical interactions and binding, and interfacial energetics and dynamics for efficient charge transfer. Recent advances in hybrid system assemblies for PEC water splitting are also briefly introduced. Finally, future challenges and directions in the field of hybrid PEC water splitting for solar energy conversion are reviewed. The current review provides state‐of‐the‐art strategies for optimized interface design for creating highly active and stable PEC water splitting assemblies.