Multiple-level Structures Research Articles

A total distance ranking approach to fuzzy AHP-based MCDM method for selecting sustainable manufacturing facility location

Selecting a sustainable facility location is a crucial strategy for manufacturing companies to achieve long-term success in today’s competitive environment. Various quantitative and qualitative criteria with different importance in a multiple level structure must be considered and aggregated to assist the company in decision-making. How to determine these criteria weights and select the sustainable manufacturing facility locations have become research questions. To resolve this problem, this paper proposes a total distance ranking approach to fuzzy analytic hierarchical process (AHP)-based multiple criteria decision-making (MCDM) method. Currently, the membership functions of fuzzy weighted ratings in the MCDM with a multilevel structure cannot be developed. A ranking method is needed to defuzzify those fuzzy numbers used for fuzzy AHP and qualitative criteria in the MCDM for better executing decision-making procedure. The total distance ranking method related to the centroid on x-axis, centroid on y-axis and the distances of centroids point to the two tangent lines of a fuzzy number are considered in the proposed ranking approach. Formulas of the proposed approach will be presented, and some properties will be investigated to derive formulas for trapezoidal and triangular fuzzy numbers. A comparison with relevant ranking methods will be made to show the advantages of the proposed ranking approach. The proposed ranking approach is then applied to defuzzify the fuzzy numbers used in fuzzy AHP and linguistic values under qualitative criteria to obtain the criteria weights under multi-level structure and crisp values under qualitative criteria, respectively. The final scores of alternatives can be obtained by aggregating crisp criteria values and their corresponding weights by simple additive weighting method to obtain the ranking result. A numerical example will be conducted to show the effectiveness of the proposed model. Finally, a comparison with Best-Worst method (BWM) will be presented to show the persuasiveness of the proposed method.

On higher-dimensional Carrollian and Galilean conformal field theories

In this paper, we study the Carrollian and Galilean conformal field theories (CCFT and GCFT) in d>2d>2 dimensions. We construct the highest weight representations (HWR) of Carrollian and Galilean conformal algebra (CCA and GCA). Even though the two algebras have different structures, their HWRs share similar structure, because their rotation subalgebras are isomorphic. In both cases, we find that the finite dimensional representations are generally reducible but indecomposable, and can be organized into the multiplets. Moreover, it turns out that the multiplet representations in d>2d>2 CCA and GCA carry not only the simple chain structure appeared in logCFT or 2d2d GCFT, but also more generally the net structures. We manage to classify all the allowed chain representations. Furthermore we discuss the two-point and three-point correlators by using the Ward identities. We mainly focus on the two-point correlators of the operators in chain representations. Even in this relative simple case, we find some novel features: multiple-level structure, shortage of the selection rule on the representations, undetermined 2-pt coefficients, etc.. We find that the non-trivial correlators could only appear for the representations of certain structure, and the correlators are generally polynomials of time coordinates for CCFT (spacial coordinates for GCFT), whose orders depend on the levels of the correlators.

Achieving Fine-Grained Data Sharing for Hierarchical Organizations in Clouds

Cloud computing has become an increasingly popular option for users to store and share data. Encryption prior to outsourcing data to the cloud is the best way to protect data security and privacy; however, it hinders sharing of the data that was encrypted. In addition, users in many real-world organizations (e.g., enterprises) have multiple level structures and a higher-level user should have the privilege to decide which data can be shared with a lower-level user. Most solutions in the literature suffer from inefficiency or inflexibility in tackling this problem. In this article, we propose a fine-grained hierarchical data sharing (FHDS) scheme in clouds. With FHDS, the data owner can encrypt data with his public key, and then selectively share encrypted data with users in a hierarchy; if necessary, the users can disseminate the owner's data to their subordinates in the lower levels by generating access keys. In particular, the higher-level users could puncture the keys with some tags such that the part of the owner's data which is labeled by the punctured tags will not be accessible to the lower-level users. The proposed scheme is provable secure under our security model and performance analyses show the efficiency of the scheme.

ROAD NETWORK EXTRACTION FROM DSM BY MATHEMATICAL MORPHOLOGY AND REASONING

The objective of this research is the automatic extraction of the road network in a scene of the urban area from a high resolution digital surface model (DSM). Automatic road extraction and modeling from remote sensed data has been studied for more than one decade. The methods vary greatly due to the differences of data types, regions, resolutions et al. An advanced automatic road network extraction scheme is proposed to address the issues of tedium steps on segmentation, recognition and grouping. It is on the basis of a geometric road model which describes a multiple-level structure. The 0-dimension element is intersection. The 1-dimension elements are central line and side. The 2-dimension element is plane, which is generated from the 1-dimension elements. The key feature of the presented approach is the cross validation for the three road elements which goes through the entire procedure of their extraction. The advantage of our model and method is that linear elements of the road can be derived directly, without any complex, non-robust connection hypothesis. An example of Japanese scene is presented to display the procedure and the performance of the approach.

A New Topology for a Single Phase Multilevel Voltage Source Inverter with Reduced Number of Components

Multilevel inverters have gained much attention for its operation involving applications ranging values of high power rating. This paper proposes a switching topology for asymmetric multilevel inverter utilizing less number of power electronics components. When the number of the output level increases, it requires more switching states and eventually the number of switching components. The increased number of switches results in higher switching losses which may lead to power loss, and reduction of efficiency of the overall conversion system. The salient feature of this proposed topology is that the module can be used as a sub multiple level structure and can be extended for any number of level with minimal increase in the switching components.

Wayfinding in Libraries: Can Problems Be Predicted?

The main library at the authors’ university campus, with its large size and multiple-level structures, is challenging for patrons to navigate. Requests for directions are among the most frequently posed questions at help desks in this library. As a first step toward improving wayfinding aids, such as maps or signs, we took a spatial science perspective of combining spatial and behavioral approaches to reveal objectively areas where wayfinding problems occur. To this end, we employed formal spatial descriptions of the environment addressing visibility, layout complexity, and connectivity. The term coined in the literature for these methods is “space syntax.” Additionally, we used a behavioral approach to investigate actual wayfinding behaviors of library patrons and compared these behaviors with the results of the space syntax analysis. The results show that a building's layout complexity and visual access potentially predicts how well patrons find their goals (books and other materials). Other aspects such as signs or individual characteristics of patrons were also found to play a role in understanding human wayfinding performance. The goal of this study was to broadly explore wayfinding problems in relation to the environment and to individual characteristics of patrons, such as their familiarity and sense of direction. Our approach introduces an objective perspective to assess wayfinding problems in libraries. Thereby, it provides potentially valuable information for library administrators towards the improvement of the design of library wayfinding systems.

Cement industry control system based on multi agent

Cement production is characterized by its great capacity, long-time delay, multi variables, difficult measurement and multi disturbances. According to the distributed intelligent control strategy based on the multi agent, the multi agent control system of cement production is built, which includes integrated optimal control and diagnosis control. The distributed and multiple level structure of multi agent system for the cement control is studied. The optimal agent is in the distributed state, which aims at the partial process of the cement production, and forms the optimal layer. The diagnosis agent located on the diagnosis layer is the diagnosis unit which aims at the whole process of the cement production, and the central management unit of the system. The system cooperation is realized by the communication among optimal agents and diagnosis agent. The architecture of the optimal agent and the diagnosis agent are designed. The detailed functions of the optimal agent and the diagnosis agent are analyzed. At last the realization methods of the agents are given, and the application of the multi agent control system is presented. The multi agent system has been successfully applied to the off-line control of one cement plant with capacity of 5 000 t/d. The results show that the average yield of the clinker increases 9.3% and the coal consumption decreases 7.5 kg/t.

Fabrication of microfluidic mixers and artificial vasculatures using a high-brightness diode-pumped Nd:YAG laser direct write method.

This paper describes a direct write laser technology, which is fast and flexible, for fabricating multiple-level microfluidic channels. A high brightness diode-pumped Nd-YAG laser with slab geometry was used for its excellent beam quality. Channels with flat walls and staggered herringbone ridges on the floor have been successfully fabricated and their ability to perform passive mixing of liquid is discussed. Also, a multi-width multi-depth microchannel has been fabricated to generate biomimetic vasculatures whose channel diameters change according to Murray's law, which states that the cube of the radius of a parent vessel equals the sum of the cubes of the radii of the daughters. The multi-depth architecture allows for flow patterns to resemble physiological vascular systems with lower overall resistance and more uniform flow velocities throughout the network compared to planar patterning techniques which generate uniformly thin channels. The ability to directly fabricate multiple level structures using relatively straightforward laser technology enhances our ability to rapidly prototype complex lab-on-a-chip systems and to develop physiological microfluidic structures for tissue engineering and investigations in biomedical fluidics problems.

Nonlinear Multilevel Dynamics of a Coupled SQUID Ring–Resonator System in the Hysteretic Regime

We consider the dynamical behavior of a strongly hysteretic SQUID ring coupled to a radio frequency resonator. By experiment we show that this system can display novel multiple level structures in its rf voltage-current characteristics which are solutions of the nonlinear equations of motion describing the system.

Can One Microscopic Model Explain the Different Behavior of Si- and Te-Related DX Centers in AlGaAs?

The method of pressure assisted studies of thermostimulated electron emission from resonant DX-levels was used to study the structure of thermal emission from Te in AlxGa1-xAs(x=0.15, 0.2, 0.25). Seven or eight components contributing to the emission process were found, as can be expected considering the possible alloy-splitting effect for a group-VI DX center in the negative-U model. The emission barriers depend on pressure and alloy composition. The possible correspondence between the configurations of DX centers and the different emission components is found, and the estimation of level positions is given. The obtained results are compared with the results for a multiple level structure of the Si-DX center. Both the similarities and differences can be understood on the grounds of a negative-U model of the DX-center.