Net Diagram Research Articles

How general is the natural frequency effect? The case of joint probabilities.

Natural frequencies are known to improve performance in Bayesian reasoning. However, their impact in situations with two binary events has not yet been completely examined, as most researchers in the last 30 years focused only on conditional probabilities. Nevertheless, situations with two binary events consist of 16 elementary probabilities and so we widen the scope and focus on joint probabilities. In this article, we theoretically elaborate on the importance of joint probabilities, for example, in situations like the Linda problem. Furthermore, we implemented a study in a 2×5×2 design with the factors information format (probabilities vs. natural frequencies), visualization type ("Bayesian text" vs. tree diagram vs. double tree diagram vs. net diagram vs. 2×2 table), and context (mammography vs. economics problem). Additionally, all four "joint questions" (i.e., were asked for. The main factor of interest was whether there is a format effect in the five visualization types named above. Surprisingly, the advantage of natural frequencies was not found for joint probabilities and, most strikingly, the format interacted with the visualization type. Specifically, while people's understanding of joint probabilities in a double tree seems to be worse than the understanding of the corresponding natural frequencies (and, thus, the frequency effect holds true), the opposite seems to be true in the 2 × 2 table. Hence, the advantage of natural frequencies compared to probabilities in typical Bayesian tasks cannot be found in the same way when joint probability or frequency tasks are asked.

Improving Diagnostic Efficiency with Frequency Double-Trees and Frequency Nets in Bayesian Reasoning.

Background. Medical students often have problems with Bayesian reasoning situations. Representing statistical information as natural frequencies (instead of probabilities) and visualizing them (e.g., with double-trees or net diagrams) leads to higher accuracy in solving these tasks. However, double-trees and net diagrams (which already contain the correct solution of the task, so that the solution could be read of the diagrams) have not yet been studied in medical education. This study examined the influence of information format (probabilities v. frequencies) and visualization (double-tree v. net diagram) on the accuracy and speed of Bayesian judgments. Methods. A total of 142 medical students at different university medical schools (Munich, Kiel, Goettingen, Erlangen, Nuremberg, Berlin, Regensburg) in Germany predicted posterior probabilities in 4 different medical Bayesian reasoning tasks, resulting in a 3-factorial 2 × 2 × 4 design. The diagnostic efficiency for the different versions was represented as the median time divided by the percentage of correct inferences. Results. Frequency visualizations led to a significantly higher accuracy and faster judgments than did probability visualizations. Participants solved 80% of the tasks correctly in the frequency double-tree and the frequency net diagram. Visualizations with probabilities also led to relatively high performance rates: 73% in the probability double-tree and 70% in the probability net diagram. The median time for a correct inference was fastest with the frequency double tree (2:08 min) followed by the frequency net diagram and the probability double-tree (both 2:26 min) and probability net diagram (2:33 min). The type of visualization did not result in a significant difference. Discussion. Frequency double-trees and frequency net diagrams help answer Bayesian tasks more accurately and also more quickly than the respective probability visualizations. Surprisingly, the effect of information format (probabilities v. frequencies) on performance was higher in previous studies: medical students seem also quite capable of identifying the correct solution to the Bayesian task, among other probabilities in the probability visualizations.HighlightsFrequency double-trees and frequency nets help answer Bayesian tasks not only more accurately but also more quickly than the respective probability visualizations.In double-trees and net diagrams, the effect of the information format (probabilities v. natural frequencies) on performance is remarkably lower in this high-performing sample than that shown in previous studies.

Seeing no net loss: Making nature offset-able

Policies for biodiversity no net loss and net gain underwrite narratives for green growth through advancing reparative logics to ongoing habitat impacts. By enabling offsetting practices that risk accommodating rather than averting land change developments, net principles are said to resemble modes of ‘accumulation by environmental restoration’. Biodiversity net principles are frequently depicted visually as a diagram of the mitigation hierarchy for communicational ease and have proliferated over recent decades despite little evidence for their ecological effectiveness. This paper combines economic sociology, visual media analysis of the net diagram and political ecology to account for the stabilisation of net principles in policy frameworks. It highlights the upstream imaginative work that this visual tool and its wider assemblages perform to support offsetting and habitat banking practices on the ground. The paper positions the NNL diagram as a conceptual and ideational technology. It traces the practices through which biodiversity is rationalised by the Cartesian coordinates of an XY schematic, and en-framed as a measure of numerical value on a vertical scale. The effect is to engender coherence to the idea of netting out differences in aggregate sums of biodiversity unit value, making nature conceptually offset-able. I develop this account through a history of the diagram as well as the broader processes that have shaped the policy and its arrival in English planning frameworks. Observers increasingly question how biodiversity offsetting and no net loss/ net gain have become so popular when their empirical foundations are so weak. This paper proposes that within the wider assemblages of actors, one answer is located in the potency and mobility of conceptual technologies such as diagrams of no net loss or net gain of biodiversity and the logic of balance-sheet accounting that is imbricated within the visual design.

Method of Risk Detection Model in Packet Filtering

This article describes Petri net diagrams for fuzzy knowledge and reasoning. A mathematical model of fuzzy Petri nets to detect risks in rules by packet filtering is formed. A model of a two-level fuzzy packet filtering system that provides packet filtering perfor-mance is presented. This model uses fuzzy Petri net as a graphical method to describe the fuzzy logical control of the movement of packets through the firewall and allows it to determine the level of threat embedded in packets from the Internet and to change the or-der of ACLs by determining the rating of acceptance and rejection of packets. In the proposed model, the packet is represented by a token in place of fuzzy Petri nets, and the operation of the packet is illustrated by the transition of fuzzy Petri net, which is responsible for moving the packet from one place to another.

Opopanax ve Crenosciadium cinsleri arasındaki filogenetik ilişkinin çekirdek ve kloroplast DNA dizisi verilerinin kullanılarak belirlenmesi

A phylogenetic study of the Opopanax and Crenosciadium was conducted to elucidate their circumscription and infrageneric relationships. Sequence data from nrDNA ITS, cpDNA matK and trnL-F were used to determine their phylogenetic relationship. Polymerase Chain Reaction (PCR) amplifications of all regions were performed using universal primers. Maximum Likelihood (ML) trees were constructed using PAUP* software, another phylogenetic tree of ITS sequences showing node ages was obtained from MrBayes programme and Neighbour Net Diagrams were constructed using Splits Tree programme. Our results clearly showed that Smyrniopsis and Opopanax are allied strongly with Petroedmondia syriaca, Magydaris panacifolia, and Crenosciadium siifolium.

Solution of seepage field in different soil layers of concrete dam foundation by flow net method

Because of the seepage problem of concrete dam foundation, the water head, pore water pressure, hydraulic gradient and seepage velocity of each point in the seepage field are obtained by drawing flow net, and finally the seepage flow is obtained to predict the seepage of dam foundation. In this paper, the flow net diagram is used to solve the pore water pressure at the fixed point of the dam foundation soil layer under three different conditions: homogeneous isotropy, homogeneous anisotropy and layered soil. The calculation accuracy of the flow net method is verified through the calculation with the finite difference software FLAC3D numerical analysis. The results indicated that the pore water pressure of the three kinds of dam foundation soil layers calculated by the flow net method is more similar from that calculated by the numerical method, which indicates that the flow net method has high accuracy and can be used in some engineering practice with difficult modeling.

Micromorphological, anatomical and molecular study of Hedera species (Araliaceae) in Iran

Hedera, with 12 extant species, is a genus of evergreen climbers native to Europe, north Africa, and south Asia. In this study, the micromorphological, anatomical structure and molecular evidences of 11 populations from two species of Hedera (H. helix and H. pastuchovii) have been considered to evaluate the relationships in Hedera. In total, seven quantitative and qualitative characters of pollen were selected and measured. Based on this study, the anticlinal wall and surface sculpturing of seed support for separation of two species of Hedera. Micromorphology of epidermis illustrated two types of epidermal cells: puzzle-shaped and polygonal cells. Using nuclear (nrDNA ITS) marker, we reconstructed phylogenetic relationships within two species of Hedera. This data set was analyzed by phylogenetic methods including Bayesian inference, maximum likelihood, and maximum parsimony. In phylogenetic analyses, all members of two species formed a well-supported clade (PP = 1; ML/BS = 100/100) and divided into two major clades (A and B). Neighbor Net diagram demonstrated separation of the studied populations. The results showed that these taxa differ in taxonomically important micromorphological, anatomical and molecular characteristics and these data provide reliable evidence for separation of these two species.

A New Visualization for Probabilistic Situations Containing Two Binary Events: The Frequency Net.

In teaching statistics in secondary schools and at university, two visualizations are primarily used when situations with two dichotomous characteristics are represented: 2 × 2 tables and tree diagrams. Both visualizations can be depicted either with probabilities or with frequencies. Visualizations with frequencies have been shown to help students significantly more in Bayesian reasoning problems than probability visualizations do. Because tree diagrams or double-trees (which are largely unknown in school) are node-branch structures, these two visualizations (in contrast to the 2 × 2 table) can even simultaneously display probabilities on branches and frequencies inside the nodes. This is a teaching advantage as it allows the frequency concept to be used to better understand probabilities. However, 2 × 2 tables and (double-)trees have a decisive disadvantage: While joint probabilities [e.g., P(A∩B)] are represented in 2 × 2 tables but no conditional probabilities [e.g., P(A|B)], it is exactly the other way around with (double-)trees. Therefore, a visualization that is equally suitable for the representation of joint probabilities and conditional probabilities is desirable. In this article, we present a new visualization—the frequency net—in which all absolute frequencies and all types of probabilities can be depicted. In addition to a detailed theoretical analysis of the frequency net, we report the results of a study with 249 university students that shows that “net diagrams” can improve reasoning without previous instruction to a similar extent as 2 × 2 tables and double-trees. Regarding questions about conditional probabilities, frequency visualizations (2 × 2 table, double-tree, or net diagram with absolute frequencies) are consistently superior to probability visualizations, and the frequency net performs as well as the frequency double-tree. Only the 2 × 2 table with frequencies—the one visualization that participants were already familiar with—led to higher performance rates. If, on the other hand, a question about a joint probability had to be answered, all implemented visualizations clearly supported participants’ performance, but no uniform format effect becomes visible. Here, participants reached the highest performance in the versions with probability 2 × 2 tables and probability net diagrams. Furthermore, after conducting a detailed error analysis, we report interesting error shifts between the two information formats and the different visualizations and give recommendations for teaching probability.

Modeling and analysis of urban rail plug door system based on Petri net and SDG diagram

The on-the-road fault diagnosis of the urban rail train passenger compartment door is a weak field in the world research. At present, most of the fault diagnosis and monitoring models for door systems are based on the analysis of historical data. Under the background of continuous development and innovation of railroad crossing equipment, it is urgent to study the model of door system suitable for online monitoring and fault diagnosis. The modeling method combining SDG(signed directed graph) diagram and Petri net is adopted. The Petri net with improved conditional fuzzy time constraint is the first layer, and the SDG diagram is the second layer. Through the dynamic simulation and concurrent processing capability of Petri net, the dynamic process simulation of the system is carried out. At the same time, the SDG map and the Petri net are connected by means of standard tables; The SDG diagram is used to construct a hazard identification and fault mining for the causal relationship between related variables in a certain state of the library. Aiming at the urban rail passenger room plug door system, the model is established and the online safety monitoring hidden danger mining process of the model method in the urban rail plug door is analyzed.

Modeling and evaluation of information systems using coloured petri network

Article history: Received January 4, 2014 Accepted 1 June 2014 Available online June 9 2014 Nowadays with the growth of organizations and their affiliates, the importance of information systems has increased. Functional and non-functional requirements of information systems in an organization are supported. There are literally several techniques to support the functional requirements in terms of software methodologies, but support for the second set of requirements has received little attention. Software Performance Engineering (SPE) forum tries to address this issue by presenting software methodologies to support both types of requirements. In this paper, we present a formal model for the evaluation of system performance based on a pragmatic model. Because of supporting the concurrency concepts, petri net has a higher priority than queuing system. For mapping UML to colored Petri net diagram, we use an intermediate graph. The preliminary results indicate that the proposed model may save significant amount of computations. © 2014 Growing Science Ltd. All rights reserved.

Quantitative and qualitative analysis of study-related patient information sheets in randomised neuro-oncology phase III-trials

IntroductionIn randomised controlled trials (RCTs), patient informed consent documents are an essential cornerstone of the study flow. However, these documents are often oversized in format and content. Clinical experience suggests that study information sheets are often not used as an aid to decision-making due to their complexity. Material and methodsWe analysed nine patient informed consent documents from clinical neuro-oncological phase III-studies running at a German Brain Tumour Centre with the objective to investigate the quality of these documents. Text length, formal layout, readability, application of ethical and legal requirements, scientific evidence and social aspects were used as rating categories. Results were assessed quantitatively by two independents investigators and were depicted using net diagrams. ResultsAll patient informed consent documents were of insufficient quality in all categories except that ethical and legal requirements were fulfilled. Notably, graduate levels were required to read and understand five of nine consent documents. DiscussionQuality deficits were consistent between the individual study information texts. Irrespective of formal aspects, a document that is intended to inform and motivate patients to participate in a study needs to be well-structured and understandable. We therefore strongly mandate to re-design patient informed consent documents in a patient-friendly way. Specifically, standardised components with a scientific foundation should be provided that could be retrieved at various times, adapted to the mode of treatment and the patient’s knowledge, and could weigh information dependent of the stage of treatment decision.

A PETRI NET BASED AGENT BEHAVIORAL TESTING

In Multi-Agent System (MAS), developers concentrate on creating design models and evolving them, from higher level models to lower level models, in several steps. Considerable part of MAS implementations is automatically produced from the design models. If a design model contains faults, they are passed to the generated implementations. Practical model validation techniques are required to discover and delete faults in abstract design models. We introduce a formal approach for agent design testing. It specifies a testing process that complements Multi-agent Systems Engineering (MaSE) methodology and strengthens the mutual relationship between UML and MAS. Besides, it defines a structured and comprehensive testing process for engineering software agents at the design level by providing a systematic way of converting the MAS design models to UML design diagram. Petri Net (PN) diagram is generated from the UML models to simulate the behavior of an agent. Because Petri Nets (PNs) are formal models, their analysis techniques can be applied to automatic agent behavioral testing.

Net diagrams for the Fomenko invariant in the integrable system with three degrees of freedom

Net diagrams for the Fomenko invariant in the integrable system with three degrees of freedom

HOMOLOGY 3-SPHERES OBTAINED BY SURGERY ON EVEN NET DIAGRAMS

In this paper, we characterize surgery presentations for <TEX>$\mathbb{Z}$</TEX>-homology 3-spheres and <TEX>$\mathbb{Z}/2\mathbb{Z}$</TEX>-homology 3-spheres obtained from <TEX>$S^3$</TEX> by Dehn surgery along a knot or link which admits an even net diagram and show that the Casson invariant for <TEX>$\mathbb{Z}$</TEX>-homology spheres and the <TEX>${\mu}$</TEX>-invariant for <TEX>$\mathbb{Z}/2\mathbb{Z}$</TEX>-homology spheres can be directly read from the net diagram. We also construct oriented 4-manifolds bounding such homology spheres and find their some properties.

Research on Automatic Generation Technology of Structural Net and Speed Diagram

In view of the teaching problems and difficulties of machinery manufacturing equipment design, the automatic generation technology of structural net and speed diagram was proposed. The conceptions and characteristics of structural formula, structural net and speed diagram were discussed. The expected targets of the automatic generation technology were put forward. The technical principles of automatically generating structural net and speed diagram were respectively analyzed. Based on these, the automatic generation software of structural net and speed diagram was designed and developed. The development environment and implementation methods of the software were proposed. It is proved that the software can play an important role in improving the teaching effect and quality.

A Petri Net Based Multi-Agent System Behavioral Testing

In Multi-Agent System (MAS), developers concentrate on creating design models and evolving them, from higher level models to lower level models, in several steps. Considerable part of MAS implementations is automatically produced from the design models. If a design model contains faults, they are passed to the generated implementations. Practical model validation techniques are required to discover and delete faults in abstract design models. In this paper, we introduce a formal approach for MAS design testing. It specifies a testing process that complements Multi-agent Systems Engineering (MaSE) methodology and strengthens the mutual relationship between UML and MAS. Besides, it defines a structured and comprehensive testing process for engineering software agents at the design level by providing a systematic way of converting the MAS design models to UML design diagram. Then a Petri Net (PN) diagram is generated from the UML models to simulate the behavior of the MAS system. Finally, because Petri Nets (PNs) are formal models, their analysis techniques can be applied to automatic MAS behavioral testing.

Survival probability of large rapidity gaps in the QCD and N=4 SYM motivated model

In this paper we present a self-consistent theoretical approach for the calculation of the Survival Probability for central dijet production. These calculations are performed in a model of high energy soft interactions based on two ingredients: (i) compatibility with the results of N=4 SYM, which at the moment is the only theory that is able to deal with a large coupling constant; and (ii) the required matching with high energy QCD. Assuming, in accordance with these prerequisites, that the soft Pomeron intercept is rather large and the slope of the Pomeron trajectory is equal to zero, we derive analytical formulae that sum both enhanced and semi-enhanced diagrams for elastic and diffractive amplitudes. Using parameters obtained from a fit to the available experimental data, we calculate the Survival Probability for exclusive central dijet production at energies accessible at the LHC. The results presented here, which include the contribution of semi-enhanced and net diagrams, are considerably larger than our previous estimates.

Sand erosion of Pelton turbine nozzles and buckets: A case study of Chilime Hydropower Plant

Erosion of hydro turbine components through sand laden river water is one of the biggest problems in the Himalayan region. This problem exists for all kinds of turbines. Apart from erosion of buckets, erosion was also observed in nozzle of the Pelton turbines due to sand particles and such problem was observed in 22 MW Chilime Hydropower Plant in Nepal. Detailed studies were conducted and erosion analysis was carried out in this case study. Sieve and mineral content analyses were systematically carried out and sediment load was calculated. By doing this, erosion rate and efficiency reduction were established using already known methodology and scenario for similar hydropower plants. The flow analysis through surface of needle was established by drawing flow net diagrams. This detrimental damage led to efficiency reduction of 1.21% consequently resulting in loss of power generation. A wear rate of 3.4 mm/year was estimated for the needle and the bucket after a systematic analysis.

A Petri Net based approach to determine the disassembly strategy of a product

In order to protect the environment and regain value added to products, a process known as disassembly has come into the limelight. This process is to be applied to reuse abandoned goods and materials. Manufacturers are being forced to establish disassembly plants and to develop their products' designs so as to maintain the government's dictate to dispose off their products in an environmentally responsible manner. This research presents a cost-based heuristic analysis for a circuit board assembly. Various components of the product and their assembly relationships are represented by a Petri Net diagram. Firing the transitions of the disassembly Petri Net is integrated with cost-based indices to develop an effective disassembly strategy. The methodology discussed here simplifies the decisionmaking process involved in disassembly planning. A comprehensive disassembly process planning system is proposed here and is exemplified by a case study of circuit board assembly.

Use of timed petri net and activity cycle diagram methodologies for modelling tandem AGVs in FMSs and their performance evaluation

This paper attempts to model the Automated Guided Vehicle (AGV) system of a flexible manufacturing system (FMS) by using timed petri net and Activity Cycle Diagrams (ACDs) as basic tools. A timed petri net used for planning of AGV system in FMSs ensures conflict-free and deadlock free operations of the system. To understand the system as it is observed in practice for delineating the behaviour of entities, the ACDhas been used. Mean utilization and the utilization index have been taken as performance measures to evaluate the system and they have been compared with previous work.