Narrow Results

The generalized LR parsing algorithm for context-free grammars is extended for the case of Boolean grammars, which are a generalization of the context-free grammars with logical connectives added to the formalism of rules. In addition to the standard LR operations, Shift and Reduce, the new algorithm uses a third operation called Invalidate, which reverses a previously made reduction. This operation makes the mathematical justification of the algorithm significantly different from its prototype. On the other hand, the changes in the implementation are not very substantial, and the algorithm still works in time O(n⁴).

The conversion of a given regular tree expression into a tree automaton has been widely studied. However, classical interpretations are based upon a top-down interpretation of tree automata. In this paper, we propose new constructions based on Gluskov’s one and on the one by Ilie and Yu using a bottom-up interpretation. One of the main goals of this technique is to consider as a next step the links with deterministic recognizers, something which cannot be done with classical top-down approaches.

This paper presents a combined model-based 3D object recognition method motivated by the robust properties of human vision. The human visual system (HVS) is very efficient and robust in identifying and grabbing objects, in part because of its properties of visual attention, contrast mechanism, feature binding, multiresolution and part-based representation. In addition, the HVS combines bottom-up and top-down information effectively using combined model representation. We propose a method for integrating these aspects under a Monte Carlo method. In this scheme, object recognition is regarded as a parameter optimization problem. The bottom-up process initializes parameters, and the top-down process optimizes them. Experimental results show that the proposed recognition model is feasible for 3D object identification and pose estimation.

Copper nanoparticles received much attention due to its high electrical conductivity, high melting point, low electrochemical migration behavior and low cost. Top down (physical methods) and bottom up (chemical and biological) approaches adopted for the synthesis of copper nanoparticles are reported. The property of copper nanoparticles mainly depends on the synthesis route and their process parameters. The influence of process parameters on the morphology, growth and yield of the nanoparticles by adopting various synthesis methods are discussed in detail. From the earlier reports, it is proved that electrochemical and chemical reduction method have received much higher attention due to their simple operation, low cost, faster reaction rate, high yield, environment friendly and low energy consumption. The characterization techniques, advantages and limitations of each synthesis methods are also discussed. The extensive applications of copper nanoparticles in various fields are also highlighted.

In some large enterprises introducing radical innovation may prove difficult, but introducing a combination of incremental changes may be more practical, particularly in the services sector where existing resources are utilized, and this may be seen as a process of entrepreneurial bricolage. For small resource-limited firms there may be no alternative but to draw on novel combinations of existing resources. The term bricolage comes from a French expression for “tinkering” and this is what it is suggested many innovative SMEs do — learn-by-doing. The notion of entrepreneurial bricolage has been used to describe a process for assembling readily available physical and knowledge assets in novel combinations for a business purpose, creating product and process “recipes”. In this paper, we explore the research question: How can entrepreneurial bricolage be represented as a coherent process?

Graphene quantum dots (GQDs) have aroused widespread attention because of their remarkable properties and potential applications. Herein, we discuss both the top-down and bottom-up strategies for the synthesis of GQDs. Different processes are presented to study their characteristics and the influence on the final properties of GQDs. The respective advantages and disadvantages of these methods are summarized. With regard to some important or novel ones, mechanisms are proposed for reference. In addition, the application of GQDs in biosensors is highlighted in detail. At last, we put forward some problems to be solved and give a brief prospect in their future developments. This review is very useful for quickly gaining knowledge and experience for synthesizing GQDs and designing the related novel biosensors.

Materials with nanoscale dimensions have unique optical properties, which have been extensively explored and implemented for a variety of functionalized photonic structures and devices. In this paper, the nanofabrication processes for photonic applications are reviewed. The nanofabrication methods can be divided into two major categories: top-down and bottom-up. The main techniques used in each method are discussed in terms of its process capabilities, advantages, limitations, and applications. The cases which involve the combination of top-down and bottom-up approaches are also illustrated.

The South Korean government aims to achieve carbon neutrality by 2050. Here, this study analyzed the economic efforts of the net-zero policy by integrating top-down and bottom-up models; The UNIfied Climate Options Nexus (UNICON) within this study aims to create a link between the 26 sectors from the bottom-up model and the 85 sectors of the top-down model. Positive mathematical programming methods were used to ensure consistency between the top-down and bottom-up models within the base year. The study found that the total reduction rate was slightly higher in the integrated model than in the computable general equilibrium (CGE) stand-alone model. In both models, the reduction rate increased when the carbon tax increased, but the marginal reduction rate was considerably lowered, and the reduction rate did not exceed 80% even with the high level of a carbon tax. The technological change of the linked industries in the integrated model showed that the steel industry had the highest emission reduction. When estimating costs for reducing GHGs, results can vary based on the technological changes under consideration.

In urban search and rescue mobile robotics, one of the most significant problems is to identify and localize trapped victims in collapsed or dangerous buildings. In order to optimize search operations, selective visual attention plays a crucial role, as it, focuses on the visual stimuli that are most relevant when identifying victims, inhibiting other stimuli in the scene. This reduces the amount of resources required for subsequent visual processing, such as recognition, and typically results in more effective and quicker search strategies. In this work, we concentrate on a purely bottom-up computational model. It functions by differentiating high-contrast areas in the image using several features including intensity, colour, and visual motion. Results for artificial and real-world images are presented, showing that the implemented system has an acceptable performance in identifying moving human body parts.