Automatic Generation of Controllers for Collision-Free Flexible Manufacturing Systems

A method for automatic generation of non-blocking controllers that generate collision-free flexible manufacturing cells is presented in this paper. Today, industry demands on flexible production sometimes require significant changes in location, orientation and configuration of industrial robots and other moving devices, when new products are introduced. All these changes pose a threat to the devices to collide while sharing workspace. To avoid this, a formal model of the operations in a manufacturing system is generated, and for each operation state a corresponding 3D simulation shape is created. A collision-free system is then achieved by considering pairs of colliding shapes as forbidden states. The automatic generation also includes a synthesis procedure, where a non-blocking and controllable supervisor is generated based on guard generation. The guards are computed by binary decision diagrams, which means that complex systems can be handled, still generating comprehensible restrictions that are easily included in PLC-code

Reduced-order synthesis of operation sequences

In flexible manufacturing systems a large number of operations need to be coordinated and supervised to avoid blocking and deadlock situations. The synthesis of such supervisors soon becomes unmanageable for industrial manufacturing systems, due to state space explosion. In this paper we therefore develop some reduction principles for a recently presented model based on self-contained operations and sequences of operations. First sequential operation behaviors are identified and related operation models are simplified into one model. Then local transitions without interaction with other operation models are removed. This reduction principle is applied to a synthesis of non-blocking operation sequences, where collisions among moving devices are guaranteed to be avoided by a flexible booking process. The number of states in the synthesis procedure and the computation time is reduced dramatically by the suggested reduction principle

Optimization of quantitative polymerase chain reactions for detection and quantification of eight periodontal bacterial pathogens

BACKGROUND: The aim of this study was to optimize quantitative (real-time) polymerase chain reaction (qPCR) assays for 8 major periodontal pathogens, i.e. Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Parvimonas micros, Porphyromonas gingivalis, Prevotella intermedia, Tanerella forsythia and Treponema denticola, and of the caries pathogen Streptococcus mutans. RESULTS: Eighteen different primer pairs were analyzed in silico regarding specificity (using BLAST analysis) and the presence of secondary structures at primer binding sites (using mFOLD). The most specific and efficiently binding primer pairs, according to these analyses, were selected for qPCR-analysis to determine amplification efficiency, limit of quantification and intra-run reproducibility. For the selected primer pairs, one for each species, the specificity was confirmed by assessing amplification of DNA extracts from isolates of closely related species. For these primer pairs, the intercycler portability was evaluated on 3 different thermal cyclers (the Applied Biosystems 7300, the Bio-Rad iQ5 and the Roche Light Cycler 480). For all assays on the different cyclers, a good correlation of the standard series was obtained (i.e. r2 >= 0.98), but quantification limits varied among cyclers. The overall best quantification limit was obtained by using a 2 mul sample in a final volume of 10 mul on the Light Cycler 480. CONCLUSIONS: In conclusion, the proposed assays allow to quantify the bacterial loads of S. mutans, 6 periodontal pathogenic species and the genus Fusobacterium.This can be of use in assessing periodontal risk, determination of the optimal periodontal therapy and evaluation of this treatment

The Overview of Cultural Dimensional Impact on Iranian Architectural Design in Foreign Project: A Case Study

A worldwide business success requires a respect for local customs. International marketers need to recognize and appreciate varying cultures. Culture plays a significant role in influencing consumer perception, which in turn influences preference and purchase. The aim of this study is to find out the most important attribute of culture characteristics impact on foreign project while the researcher take into consideration the model of Rabi and Bhagat, 2008.Iranian architectural companies were asked to evaluate the dimension of culture when they accomplished the project in abroad. Cumulative, Socially shared, Facilitate communications learned subjective, enduring, perspective and dynamic, are the main dimension on culture which caused main influence on designing. The questionnaire finally consisted of twenty and four statements as a driving factor and architectural company were asked to indicate the degree of importance. It was administrated to ninety one architectural companies with grade 1 participated in this Research in Tehran , therefore the snowball sampling method is an appropriate non probability sampling method to collect the date . The result showed that, communication, learned and subjective dimensions of culture should take into consideration when they are designing the project performed in abroad through Iranian architectural company. To put in the nutshell, the Iranian architectural companies with grade 1 need more emphasis on Touristic city, Prevalence of internet utilization and Citizens-Foreigners communication as various pillars of communication. Key words: Culture; Architectural; Design; Perspective; Communication; Subjective; Dimension; Ira

A Process Algebra for Supervisory Coordination

A supervisory controller controls and coordinates the behavior of different components of a complex machine by observing their discrete behaviour. Supervisory control theory studies automated synthesis of controller models, known as supervisors, based on formal models of the machine components and a formalization of the requirements. Subsequently, code generation can be used to implement this supervisor in software, on a PLC, or embedded microprocessor. In this article, we take a closer look at the control loop that couples the supervisory controller and the machine. We model both event-based and state-based observations using process algebra and bisimulation-based semantics. The main application area of supervisory control that we consider is coordination, referred to as supervisory coordination, and we give an academic and an industrial example, discussing the process-theoretic concepts employed.Comment: In Proceedings PACO 2011, arXiv:1108.145

Comparison of Implant Stability Using Resonance Frequency Analysis: Osteotome versus Conventional Drilling

Objectives: Implant primary stability is one of the important factors in achieving implant success. The osteotome technique may improve primary stability in patients with poor bone quality. The aim of this study was to compare implant stability using two different techniques namely osteotome versus conventional drilling in the posterior maxilla. Materials and Methods: In this controlled randomized clinical trial, 54 dental implants were placed in 32 patients; 29 implants were placed in the osteotome group and 25   in the conventional drilling group. Implant stability was assessed at four time intervals namely at baseline, one, two and three months after implant placement using resonance frequency analysis (RFA). Results: Primary stability based on implant stability quotient (ISQ) units was 71.4±7 for the osteotome group and 67.4±10 for the control group. There was no statistically significant difference between the two groups in implant stability at any of the measurement times. In each group, changes in implant stability from baseline to one month and also from two months to three months post-operatively were not significant but from one month to two months after implant placement, implant stability showed a significant increase in both groups.   Conclusion: The results of this study revealed that in both techniques, good implant stability was achieved and osteotome technique did not have any advantage compared to conventional drilling in this regard

Recommandations relatives a l'utilisation d'agents anti-bacteriens dans le traitement de la parodontite chronique en Belgique

Mechanical debridement, with of without flap elevation, is a difficult and technique-sensitive procedure resulting in suboptimal treatment outcome from time to time. Therefore, it is not surprising that antibiotics and antiseptics, used alone or in combination with scaling and root planing, have always been fairly successful in clinical practice. For a number of reasons discussed in this paper, routine use of these agents cannot be justified. Especially in general practice these agents should not be prescribed; at least not for treating periodontitis