On extremal cases of Hopcroft’s algorithm

In this paper we consider the problem of minimization of deterministic finite automata (DFA) with reference to Hopcroft’s algorithm. Hopcroft’s algorithm has several degrees of freedom, so there can exist different executions that can lead to different sequences of refinements of the set of the states up to the final partition. We find an infinite family of binary automata for which such a process is unique, whatever strategy is chosen. Some recent papers (cf. Berstel and Carton (2004) [3], Castiglione et al. (2008) [6] and Berstel et al. (2009) [1]) have been devoted to find families of automata for which Hopcroft’s algorithm has its worst execution time. They are unary automata associated with circular words. However, automata minimization can be achieved also in linear time when the alphabet has only one letter (cf. Paige et al. (1985) [14]), but such a method does not seem to extend to larger alphabet. So, in this paper we face the tightness of Hopcroft’s algorithm when the alphabet contains more than one letter. In particular we define an infinite family of binary automata representing the worst case of Hopcroft’s algorithm, for each execution. They are automata associated with particular trees and we deepen the connection between the refinement process of Hopcroft’s algorithm and the combinatorial properties of such trees.     

Experimental determination of phase equilibria in the Y–Co–Ti system through diffusion couples and equilibrium alloys

Two isothermal sections of the Y–Co–Ti system at 600 °C and 800 °C were constructed for the first time using the diffusion couple technique and the equilibrium alloy method in combination with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electron probe microanalysis (EPMA), and X-ray diffraction (XRD). The stable ternary intermetallic compound YCo_12-xTi_x was detected and was confirmed to have a ThMn₁₂-type structure. The composition range in this ternary compound was measured to be 8.3–18.2 at.% at 600 °C and 8.9–19.1 at.% at 800 °C, resulting in the stable formation of YCo_12-xTi_x with x = 1.1–2.4 at 600 °C and x = 1.2–2.5 at 800 °C. The experimental results measured by EDS and EPMA demonstrate that the maximum solubilities of Ti in YCo₂, YCo₃, Y₂Co₇ and Y₂Co₁₇ compounds at 600 °C are 3.3, 5.6, 5.7 and 6.6 at.%, respectively, while the maximum solubilities of Y in Co₃Ti, Co₂Ti(h), Co₂Ti(c) and CoTi compounds are 2.7, 2.1, 2.6, 3.8 and 1.1 at.%. Meanwhile, the maximum solubilities of Ti in YCo₃, Y₂Co₇, YCo₅ and Y₂Co₁₇ compounds at 800 °C were determined to be 5.4, 3.2, 2.5 and 5.4 at.%, respectively, while the maximum solubilities of Y in Co₂Ti(c), Co₂Ti(h) and Co₃Ti compounds were measured to be 2.5, 2.1 and 3.8 at.%. The phase equilibria of the Y–Co–Ti system obtained in this work would provide the experimental information for phase stability of YCo_12-xTi_x compound and then explore the design of Y–Co–Ti based magnetic alloys with good magnetic properties.     

Sense’s standards and machine understanding of texts in the system for computer-aided testing of knowledge

This paper proposes an approach to interpreting a response an answer to a test task of an open form in a system for computer-aided testing of knowledge. The notion of a sense’s standard is introduced; and the method for building it based on the set of semantic equivalent phrases of natural language and use of sense’s standards for compression of a textual knowledge base are described.     

The open question of the relation between square matrix’s eigenvalues and its similarity matrix’s singular values in linear discrete system

In linear discrete system, we often need to utilize similarity transformation to extend the solution ranges of its corresponding discrete matrix equations. Consequently, how to choose the similarity transformation matrix remains an open question in recent years. In this paper, by applying the theory of matrix’s Jordan canonical form and the related properties of nonnegative matrices, we construct the similarity transformation matrix of some special similarity transformation, then present a necessary and sufficient condition and a corresponding algorithm, thus solve the open question totally.     

Experimental investigation of phase equilibria in the Ce-Fe-Ni system at 950 and 750 °C

The Ce-Fe-Ni system has been experimentally studied by microstructural analysis, electron microprobe analysis and X-ray diffraction over the whole concentration range. Isothermal sections at 950 and 750 °C for this system were constructed for the first time. The phase relations at 750 °C measured in this work are different from those published for 700 °C in particular because of the identification of a new binary phase Ce₅Ni₁₉. A continuous solid solution Ce(Fe,Ni)₂ (MgCu₂-type structure, cF24-Fd-3m), was found at 750 °C, with mutual substitution of Fe and Ni atoms. The liquid phase is present in the system both at 950 and 750 °C. Almost all binary-based phases at these temperatures show wide homogeneity regions and possess a constant Ce content.     

Design of hybrid type’s optical pickup actuator for system stability in high density reading and recording

Recently, there has been a trend to have large capacity and high data transfer rate in optical disk drive. Pickup actuator also should have high performance for satisfying this trend. Since moving magnet type actuator has more simple and robust structure than moving coil type one, we designed moving magnet type to accomplish high flexible mode frequency. However, the driving sensitivity of moving magnet type actuator was low because of its characteristics as following. At first, moving parts including magnets are heavy and electromagnetic (EM) circuits are not closed-loop owing to yoke composed of paramagnetic materials. Therefore, in order to increase the driving sensitivity without the degradation of the other dynamic characteristics, EM circuits were redesigned by adding solenoid coils on existing mechanism. As a result, the hybrid type actuator composed of moving magnet type and moving coil type was suggested to obtain high sensitivities and high flexible mode frequency. Design variables of EM circuits and structure parts were decided through parametric study and design of experiments procedure. Optimization algorithm using variable metric method was used to improve performance. Based on these results, the final model was presented.     

Experimental investigation of phase relationship in Ti–Fe-Hf ternary system

Based on diffusion triple and equilibrated alloy methods, phase relations in the Ti–Fe-Hf ternary system were investigated using the experimental data obtained through the combination of optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA) techniques. Isothermal sections of the Ti–Fe-Hf system at both 1073 K and 1273 K were well constructed. There are three and four three-phase regions in these two sections, respectively. According to the present results, Hf can dissolve into FeTi at approximately 3.0% at both 1073 K and 1273 K. A continuous solid solution of Fe₂(Ti, Hf) forms between the binary intermediate compounds Fe₂Ti and Fe₂Hf (h). Fe₂Hf(c) and FeHf₂ show large solid solubilities. The solubility of Ti in Fe₂Hf(c) changes from 33.9% at 1073 K to 39.0% at 1273 K, while that of FeHf₂ can reach up to approximately 63.0% at 1273 K. No ternary compound exists in the Ti–Fe-Hf ternary system.     

Murray’s law and the bifurcation angle in the arterial micro-circulation system and their application to the design of microfluidics

Murray’s law which is related to the bifurcations of vascular blood vessels states that the cube of a parent vessel’s diameter equals the sum of the cubes of the daughter vessels’ diameters D₀³ = D₁³ + D₂³ , a = D₀³ /( D₁³ + D₂³ ) = 1, D_{0}^{3} = D_{1}^{3} + D_{2}^{3} ,,alpha = D_{0}^{3} /left( {D_{1}^{3} + D_{2}^{3} } right) = 1, where D ₀, D ₁, and D ₂ are the diameters of the parent and two daughter vessels, respectively and α is the ratio). The structural characteristics of the vessels are crucial in the development of the cardiovascular system as well as for the proper functioning of an organism. In order to understand the vascular circulation system, it is essential to understand the design rules or scaling laws of the system under a homeostatic condition. In this study, Murray’s law in the extraembryonic arterial bifurcations and its relationship with the bifurcation angle (θ) using 3-day-old chicken embryos in vivo has been investigated. Bifurcation is an important geometric factor in biological systems, having a significant influence on the circulation in the vascular system. Parameters such as diameter and bifurcation angle of all the 140 vessels tested were measured using image analysis softwares. The experimental results for α (= 1.053 ± 0.188) showed a good agreement with the ratio of 1 for Murray’s law. Furthermore, the diameter relation α approached the theoretical value of 1 as the diameter of parent vessel D ₀ decreased below 100 μm. The bifurcation angle θ decreased as D ₀ increased and vice versa. For the arterial bifurcations of chicken embryos tested in this study, the bifurcation pattern appears to be symmetric (D ₁ = D ₂). The bifurcation angle exhibited a nearly constant value of 77°, close to the theoretical value of 75° for a symmetric bifurcation.     

The digitization of a food package’s life cycle: Existing and emerging computer systems in the logistics and post-logistics phase

At present, the food and food packaging industry is increasingly confronted with and gently forced by consumers and governmental organizations to resolve issues related to food fraud, counterfeit, theft, food quality and safety, and package reuse and recycling. This requires the development and/or integration of new or existing technologies such as intelligent food packages or wireless sensor networks to improve monitoring capabilities during logistics and sales and consumption, allow interaction with consumers, and improve the reuse or recycling of food packages. In this review paper, an extensive overview is provided of computer systems that are used in the logistics and post-logistics phase of a food package’s life cycle and that to a certain extent integrate the aforementioned technologies. These systems offer the perspective to improve the efficiency of logistics operations on food packages to reduce food loss, better inform consumers through food packages, and support package reuse and recycling. The main purpose of this review paper is to encourage the academia and engineers to tackle existing research challenges and resolve technical issues related to the development of new integrated computer systems.     

Perception of Order and Ambiguity in Leonardo’s Design Concepts

Leonardo da Vinci used geometry to give his design concepts both structural and visual balance. The paper examines aesthetic order in Leonardo’s structural design, and reflects on his belief in analogy between structure and anatomy. Leonardo’s drawings of grids and roof systems are generated from processes best known from ornamentation and can be developed into spatial structures assembled from loose elements with no need for binding elements. His architectural plans are patterns based on principles of tessellation, tiling and recursion, also characteristic of the reversible, ambiguous structures which led to Leonardo’s further inventions in structural and mechanical design as well as dynamic representations of space in his painting. In recent times, the ambiguous structures in the art of Joseph Albers, the reversible and impossible structures of M. C. Escher, the recurring patterns and spherical geometry of Buckminster Fuller and the reciprocal grids in structural design of Cecil Balmond display a similar interest. Computer models and animations have been used to simulate processes of perceiving and creating ambiguity in structures.     

Impacts of low citizen awareness and usage in smart city services: the case of London’s smart parking system

Smart city applications and services are increasingly considered as strategic means to cope with emerging global challenges such as climate change, pollution, the ageing population, and energy shortage. In particular, smart parking is a type of smart services used to improve traffic congestion and pollution within cities. Nevertheless, although smart city services are driven by advanced information technologies, their success is highly dependent on user engagement, which is historically problematic. This paper presents and discusses the results of a case study on the smart parking service in London. A questionnaire (involved a total of 212 local drivers) was adopted as the main data collection method. This was complemented by the collection and analysis of 470 online user comments left for the service. The results showed that London’s smart parking service may potentially help each driver to save an average of £68 (62.2 l) on petrol annually and reduce CO₂ emissions by 238.14 kg per car per year. At city level, a smart parking system could help London save £183.6 million worth of petrol per year and reduce its annual CO₂ emissions by 642,978 tons. However, public awareness, actual usage, and user satisfaction of this smart service are currently very low. These present substantial barriers to realise the potential economic and environmental benefits of the service. This paper concluded that further to the very technological efforts, local authorities and service providers need to make a stronger endeavour to enhance public engagement and user satisfaction towards smart services, in order to realise the promises of such solutions.     

The digitization of a food package’s life cycle: Existing and emerging computer systems in the pre-logistics phase

Traditional design and production methods for food packages become less and less suitable to rapidly respond to ever-changing requirements and regulations. Computer systems applied in discrete manufacturing (ranging from computer-aided-technologies to image analysis systems) are now also specifically developed for and gradually adopted by the food package industry to improve efficiency in terms of material usage, operational costs, and food loss, and to allow the development of more performant and sustainable food packages. In this paper, an extensive overview is provided of such systems that, when combined, offer the perspective to realize a more holistic research, design and production approach that fits within the spirit of the fourth industrial revolution. Special attention is given to the importance of information from and knowledge about the logistics and post-logistics phase of a food package's life cycle in the manufacturing process. The main purpose of this review paper is to provide, for the first time, a complete and coherent overview of the digitization of a food package's life cycle that can be used as a blueprint for future research, development and discussion in this emerging research topic.     

A thermodynamic description and phase relationships of the FeCr system: Part I the BCC phase and the sigma phase

A generalized approach which was applied successfully to account for the magnetic contribution to the thermodynamic properties of FeNi is applied to FeCr. The predicted magnetic specific heats for two bcc alloys at x_Cr = 0.16 and 0.21 are in good agreement with the experimental data available in the literature. The magnetic Gihbs energy, enthalpy and entropy for the bcc phase are obtained accordingly. The nonmagnetic thermodynamic properties of the bcc phase are obtained primarily from thermochemical data as well as those for the sigma phase. The calculated stable and metastable equilibria involving the bcc and sigma phases are in reasonable agreement with data reported in the literature. The calculated metastable miscibility gap of the bcc phase is highly asymmetric and the calculated spinodals show unusual features.     

A Thermodynamic description and phase relationships of the FeCr system: Part II the liquid phase and the fcc phase

The high-temperature thermodynamic data and phase equilibria of the FeCr binary reported in the literature are assessed. A set of thermodynamic values for the liquid, bcc and fcc phases are obtained. These values are internally consistent and the calculated phase equilibria are in agreement with the measured phase boundary data. Metastable equilibria for the liquid and fcc phases are also calculated.     

Complexity analysis of the Pawlak’s flowgraph extension for re-identification in multi-camera surveillance system

The idea of Pawlak’s flowgraph turned out to be a useful and convenient container for a knowledge of objects’ behaviour and movements within the area observed with a multi-camera surveillance system. Utilization of the flowgraph for modelling behaviour admittedly requires certain extensions and enhancements, but it allows for combining many rules into a one data structure and for obtaining parameters describing how objects tend to move through the supervised area. The main aim of this article is presentation of the complexity analysis of proposed modification of flowgraphs. This analysis contains considerations of issues such as memory efficiency and computational complexity of operations on the flowgraph. The measures related to space and time efficiency were also included.     

System analysts’ orientations and perceptions of system failure

System analysts approach tasks with different orientations to their actions. Likewise, system failures are perceived to be because of a variety of causes. A survey of 239 analysts is conducted to explore the similarities between these orientations and perceptions of failure reasons. The findings indicate that analysts’ perceptions of failure reasons and their approach to development fall along similar lines. This trait enables information system management to select project teams to help avoid failures. The variety of orientations needed for success can be chosen from within the organization or training of analysts can be targeted more effectively to consider missing elements based on current orientations.