Partitioning approach oriented to the decentralised predictive control of large-scale systems

This systematic review aimed to evaluate if the internal connection is more efficient than the external connection and its associated influencing factors. A specific question was formulated according to the Population, Intervention, Control, and Outcome (PICO): Is internal connection more efficient than external connection in mechanical, biological, and esthetical point of views? An electronic search of the MEDLINE and the Web of Knowledge databases was performed for relevant studies published in English up to November 2013 by two independent reviewers. The keywords used in the search included a combination of "dental implant" and "internal connection" or "Morse connection" or "external connection." Selected studies were randomized clinical trials, prospective or retrospective studies, and in vitro studies with a clear aim of investigating the internal and/or external implant connection use. From an initial screening yield of 674 articles, 64 potentially relevant articles were selected after an evaluation of their titles and abstracts. Full texts of these articles were obtained with 29 articles fulfilling the inclusion criteria. Morse taper connection has the best sealing ability. Concerning crestal bone loss, internal connections presented better results than external connections. The limitation of the present study was the absence of randomized clinical trials that investigated if the internal connection was more efficient than the external connection. The external and internal connections have different mechanical, biological, and esthetical characteristics. Besides all systems that show proper success rates and effectiveness, crestal bone level maintenance is more important around internal connections than external connections. The Morse taper connection seems to be more efficient concerning biological aspects, allowing lower bacterial leakage and bone loss in single implants, including aesthetic regions. Additionally, this connection type can be successfully indicated for fixed partial prostheses and overdenture planning, since it exhibits high mechanical stability.

The mechanical performance of cemented or screw-retained implant-supported crowns with an internal or external configuration is yet to be understood. This in vitro study evaluated the effect of screw-retained and cement-retained prostheses on internal and external implant-abutment connections. Thereby, the reliability and failure modes of crowns were investigated. Eighty-four implants (Emfils; Colosso Evolution system) were divided into four groups (n=21 each): screw-retained and internal connection (Si), screw-retained and external connection (Se), cement-retained and internal connection (Ci), and cement-retained and external connection (Ce). Ti-6Al-4V abutments were torqued (30 Ncm) to the implants, and maxillary central incisor metal crowns were torqued (30 Ncm) or cemented (Rely X Unicem; 3M-ESPE) and subjected to accelerated life-testing in water. Use-level probability Weibull curves and reliability for 50,000 cycles at 150 N were calculated. The β values for Si (1.72), Se (1.50), Ci (1.34), and Ce (1.77) groups indicated that fatigue/damage accumulation accelerated their failure. The Ci group presented the highest reliability, the Se group presented the lowest reliability, and Si and Ce groups presented intermediate reliability. Screw-retained restorations presented mainly abutment fracture. Cement-retained restorations resulted in failures of the screw in the Ce group, but implant/screw fracture in the Ci group.

High-speed rail (HSR) is an important form of transportation that affects the economic development of the regional spatial structure. However, there is less discussion about the impact of economically underdeveloped regions and the rapid construction of HSR on the region. This study uses a spatial econometric model to explore whether a rapidly formed high-speed rail network with changes in the network structure can bring economic effects based on the spatio-temporal panel data on high-speed rail construction and economic development in western China from 2015 to 2020. First, data of the daily departures between high-speed rail cities were used to analyze the western high-speed rail network’s spatial and temporal evolution characteristics. Second, we analyzed the changes in the centrality, external and internal connectivity, and transfer potential of the economic gap of the western HSR network. Finally, we analyzed the different economic effects of the HSR network structure by combining the Cobb–Douglas production function with the spatial econometric model. The conclusions are as follows: (1) The HSR network in western China is dense at the intra-provincial HSR network; then it expands along the cross-provincial region; and is gradually embedded in the national HSR network, forming a figure-8-shaped spatial structure. (2) In the rapid expansion and densification of the HSR network in western China, connectivity takes precedence, and dominance and control are then increased. The external connectivity of the western HSR city network develops first and shows fluctuating growth, while the internal connectivity improves relatively slowly. (3) The connectivity, convenience of transit, transshipment capacity, and internal and external connection structure of the HSR network all contribute to the economic development of western cities. The transfer potential of economic gaps is detrimental to their economic development but has a positive effect on adjacent cities.

In recent years, the rapid growth of the Internet has led to creation of massively large graphs. Since databases have become very large nowadays, they cannot be processed by a simple machine at an acceptable time anymore; therefore, traditional graph partitioning methods, which are often based on having a complete image of the entire graph, are not applicable to large datasets. This challenge has led to the appearance of a new approach called streaming graph partitioning. In streaming graph partitioning, a stream of input data is received by a partitioner, and partitioner decides which computational machine the data should be transferred to. Often, streaming partitioner does not have any information about the whole graph, and usually distributes the vertices based on some greedy heuristics which may not be optimal for incoming vertices. Hence, partitioner’s decision can be significantly improved if more information about the graph is utilized. In this paper, we present a new vertex-cut streaming graph partitioning approach. The proposed method uses the idea of postponing the decision for some of the edges (by means of an intelligent buffering) and corrects some of the past decisions to improve the quality of the graph partitioning. The proposed approach is evaluated using from real-world graphs. The experimental results show that the performance of the proposed method is superior in comparison with the previous HDRF method.

This paper focuses on water demand forecasting for predictive control of Drinking Water Networks (DWN) in the short term by using Gaussian Process (GP). For the predictive control strategy, system states in a finite horizon are generated by a DWN model and demands are regarded as system disturbances. The goal is to provide a demand estimation within a given confidence interval. For the sake of obtaining a desired forecasting performance, the forecasting process is carried out in two parts: the expected part is forecasted by Double-Seasonal Holt-Winters (DSHW) method and the stochastic part is forecasted by GP method. The mean value of water demand is firstly estimated by DSHW while GP provides estimations within a confidence interval. GP is applied with random inputs to propagate uncertainty at each step. Results of the application of the proposed approach to a real case study based on the Barcelona DWN have shown that the general goal has been successfully reached.

In model predictive control (MPC) for large-scale applications, the computational limitations for on-line optimization often lead to the use of (relatively) short prediction horizons. In this paper, we show that as a result, the controller optimizes over only a fraction of the dynamics of the large-scale system. Based on this observation, which we will formalize, we propose a method to construct reduced-order models of minimal order, by exploiting the system-theoretic concept of finite-horizon observability, that exactly match the response of the large-scale system within a finite horizon. These so-called finite-horizon minimal realizations are used to implement equivalent MPC schemes with reduced computational effort (or the same computational effort but with a larger prediction horizon) without sacrificing accuracy/performance (as the equivalent optimization problem has the same optimizers as the original MPC problem). By computing finite-horizon minimal realizations, we can determine the dynamics as "seen" by the MPC, which can provide useful design insights, in particular, when tuning the prediction horizon. We demonstrate the strengths of our results in a numerical case study.

Efficient circuit partitioning is gaining more importance with the increasing size of modern circuits. Conventionally, circuit partitioning is solved by modeling a circuit as a hypergraph for the ease of applying graph algorithms. However there exists room for further improvement on even optimum hypergraph partitioning results, if logic information can be applied for perturbation. In this paper we present a multi-way partitioning framework which can couple any excellent hypergraph partitioner and a noval logic perturbation based technique (GBAW) for further improvement over very excellent partitioning results. Our approach can integrate with any graph partitioner. We performed experiments on 2-, 3-, 4-, and 5-way partitionings for various circuits of different sizes from MCNC benchmarks. We have chosen the state-of-the-art hMetis-Kway to obtain high quality initial solutions for the experiments. Our experiments showed that this partitioning approach can achieve a further 15% reduction in cut size for 2-way partitioning with an area penalty of only 0.33%. The good results demonstrated the effectiveness of this new partitioning technique.

\n Vertex-centric graph processing systems such as Pregel, PowerGraph,\n or GraphX recently gained popularity due to their superior\n performance of data analytics on graph-structured data. These\n systems exploit the graph structure to improve data access locality\n during computation, making use of specialized graph partitioning\n algorithms. Recent partitioning techniques assume a uniform and\n constant amount of data exchanged between graph vertices (i.e.,\n uniform vertex traffic) and homogeneous underlying network costs.\n However, in real-world scenarios vertex traffic and network costs\n are heterogeneous. This leads to suboptimal partitioning decisions\n and inefficient graph processing. To this end, we designed GrapH,\n the first graph processing system using vertex-cut graph\n partitioning that considers both, diverse vertex traffic and\n heterogeneous network, to minimize overall communication costs. The\n main idea is to avoid frequent communication over expensive network\n links using an adaptive edge migration strategy. Our evaluations\n show an improvement of 60% in communication costs compared to\n state-of-the-art partitioning approaches.\n

This paper proposes the application of a distributed command governor (DCG) strategy for the operational control of drinking water networks (DWN). This approach is very suitable to this kind of management problems given the large-scale and complex nature of DWNs, the relevant effect of persistent disturbances (water demands) over the network evolutions and their marginal stability feature. The performance improvement offered by DCG is compared with the consideration of two non-centralized model predictive control (MPC) approaches already proposed for the same management purposes and within the same context. The paper also discusses the effectiveness of all strategies and highlights the advantages of each approach. The Barcelona DWN is considered as the case study for the assessment analysis.

An ‐graph is a graph that can be partitioned into r independent sets and ℓ cliques. In the Graph Coloring problem, we are given as input a graph G, and the objective is to determine the minimum integer k such that G admits a proper vertex k‐coloring. In this work, we describe a Poly versus NP‐hard dichotomy of this problem regarding the parameters r and ℓ of ‐graphs, which determine the boundaries of the ‐hardness of Graph Coloring for such classes. We also analyze the complexity of the problem on ()‐graphs under the parameterized complexity perspective. We show that given a (2, 1)‐partition of a graph G, finding an optimal coloring of G is ‐complete even when K1 is a maximal clique of size 3; XP but W[1]‐hard when parameterized by ; fixed‐parameter tractable (FPT) and admits a polynomial kernel when parameterized by . Besides, concerning the case where K1 is a maximal clique of size 3, a P versus NPh dichotomy regarding the neighborhood of K1 is provided; furthermore, an FPT algorithm parameterized by the number of vertices having no neighbor in K1 is presented.

Evolutionary multi-objective overlapping community detection based on fusion of internal and external connectivity and correction of node intimacy

Graph matching, set covering and partitioning problems are both theoretically and practically important in decision support systems. Numerous situations have been modeled as graph matching, set covering and partitioning problems. These situations include applications in the areas of task assignment, marriage problem, airline crew scheduling, truck deliveries or vehicle routing, political redistricting, etc. Relational database systems currently support these applications merely by providing some programming languages which are used to write the programs associated with the data. These programming languages are complete as opposed to existing query languages like SQL. These languages, since they are complete, have the usual complexity of a powerful language and lack the simplicity of query languages. This increases application development effort. Relational operators and the query language SQL are extended in this present work in order to enable these problems to be stated and solved directly by the relational database systems leading to benefits of improved data independence, increased productivity, and better performance. The relational operators are extended with six operators, i.e., match, maxmatch, cover, mincover, partition, and minpartition. Properties of these operators are described. Some of these operators may possibly take a very long time in finding a solution. Genetic algorithms are proposed. These algorithms are bounded by a polynomial time. These algorithms therefore enable DBMS to be capable of responding to queries involving proposed operators in a given time constraint. The database operations and query languages extended in this research provide a powerful tool for users as a database‐query tool which supports some decision support systems for information retrieval from a database.

Mechanisms without redundant connections, including gripper mechanisms, are more reliable, have a higher efficiency of operation and are statically determined. It is difficult to design such mechanisms without thorough structural analysis. A structural analysis of the paired parallelogram schemes of the gripping devices, which are built on the basis of the central and deaxial crank-slider mechanisms and have a variable structure with external one-way connections, was performed. The number of internal and external redundant connections in the contours of the mechanisms at different stages of their functioning is determined. Their location in the contours is determined and actions are proposed to eliminate them in the internal contours and reduce the number of harmful redundant connections in the external contour of the mechanisms. The elimination of frictional excess connections in the outer contour of the mechanisms by changing the shapes of the contacting surfaces of the clamping elements of the gripper is considered.

k-way graph partitioning is an NP-complete problem, which is applied to various tasks such as route planning, image segmentation, community detection, and high-performance computing. The approximate methods constitute a useful solution for these types of problems. Thus, many research studies have focused on developing meta-heuristic algorithms to tackle the graph partitioning problem. Local search is one of the earliest methods that has been applied efficiently to this type of problem. Recent studies have explored various types of local search methods and have improved them such that they can be used with the partitioning process. Moreover, local search methods are widely integrated with population-based approaches, to provide the best diversification and intensification for the problem space. This study emphasizes the local search approaches, as well as their combination with other graph partitioning approaches. At present, none of the surveys in the literature has focused on this class of state of the art approaches in much detail. In this study, the vital parts of these approaches including neighborhood structure, acceptance criterion, and the ways of combining them with other approaches, are highlighted. Additionally, we provide an experimental comparison that shows the variance in the performance of the reviewed methods. Hence, this study clarifies these methods to show their advantages and limitations for the targeted problem, and thus can aid in the direction of research flow towards the area of graph partitioning.

PurposeThe purpose of this retrospective study with 4–12 years of follow-up was to compare the marginal bone loss (MBL) between external-connection (EC) and internal-connection (IC) dental implants in posterior areas without periodontal or peri-implant disease on the adjacent teeth or implants. Additional factors influencing MBL were also evaluated.MethodsThis retrospective study was performed using dental records and radiographic data obtained from patients who had undergone dental implant treatment in the posterior area from March 2006 to March 2007. All the implants that were included had follow-up periods of more than 4 years after loading and satisfied the implant success criteria, without any peri-implant or periodontal disease on the adjacent implants or teeth. They were divided into 2 groups: EC and IC. Subgroup comparisons were conducted according to splinting and the use of cement in the restorations. A statistical analysis was performed using the Mann-Whitney U test for comparisons between 2 groups and the Kruskal-Wallis test for comparisons among more than 2 groups.ResultsA total of 355 implants in 170 patients (206 EC and 149 IC) fulfilled the inclusion criteria and were analyzed in this study. The mean MBL was 0.47 mm and 0.15 mm in the EC and IC implants, respectively, which was a statistically significant difference (P<0.001). Comparisons according to splinting (MBL of single implants: 0.34 mm, MBL of splinted implants: 0.31 mm, P=0.676) and cement use (MBL of cemented implants: 0.27 mm, MBL of non-cemented implants: 0.35 mm, P=0.178) showed no statistically significant differences in MBL, regardless of the implant connection type.ConclusionsIC implants showed a more favorable bone response regarding MBL in posterior areas without peri-implantitis or periodontal disease.