PAT Model Research Articles

FVF-AKA: A Formal Verification Framework of AKA Protocols for Multi-server IoT

As IoT in a multi-server environment increases resources’ utilization, more and more problems of IoT authentication and key agreement are being revealed. The Authentication and Key Agreement (AKA) protocol plays an important role in solving these problems. Many AKA protocols have been proposed, and some of them support their own verifications. However, a unifying verification framework for multi-server IoT is lacking. In this article, we propose a formal verification framework of AKA protocols for multi-server IoT (FVF-AKA). It supports the construction of CSP models for the AKA protocol, the implementation of the CSP models in PAT with C#, and the verification of formal models. With the help of C#, many complex functions in the AKA protocol can be implemented. We also design an algorithm to support automatic conversion from the CSP model to the PAT model. FVF-AKA can verify four fundamental properties (deadlock freedom, entity legitimacy, timeout delay, and session key consistency). It also supports the verification of security properties for the AKA protocol suffering from four different attacks (relay attacks, denial of service attacks, server spoofing attacks, and session key attacks). Our approach can be applied to most AKA protocols for multi-server IoT generally. By applying FVF-AKA to two AKA protocols, we can verify whether they satisfy the fundamental properties and analyze their security properties in vulnerable environments. Our work would help to analyze the AKA protocol for multi-server IoT and provide the foundation for the analysis of enhancing its security and robustness.

Yaozhou Kiln Museum e-commerce applet mindstream experience design practice

In this paper, we design and practice the e-commerce applet platform of Yaozhou Kiln Museum to help the development of Yao porcelain culture. Based on the heart flow theory and the PAT model, we analyze the factors that generate the heart flow experience in the e-commerce applet of Yaozhou Kiln Museum, summarize the factors from the five elements of user experience and then classify them, and build a design model for the e-commerce applet of Yaozhou Kiln Museum. According to the results of user satisfaction survey, it can be seen that the heart flow experience of Yaozhou Kiln Museum e-commerce applet has good satisfaction in three perspectives of visual experience, interactive experience and emotional perception experience, which can enhance users' willingness to use the platform to stimulate heart flow. Therefore, the introduction of mind flow theory into the design of e-commerce applet of Yaozhou Kiln Museum can strengthen the link between users and the platform and explore more possibilities for the establishment of e-commerce applet of Yaozhou Kiln Museum from the perspective of optimal experience.

Plot-aware transformer for recommender systems

<abstract> <p>Plot text is very valuable supporting information in movie recommendations. It has several characteristics: 1) It is rich in content. Each movie often has a document of more than 200 words to describe it, which can give the movie a rich semantic meaning. 2) Objectivity. Plot texts are different from review information. A movie may have thousands of reviews with mixed and conflicting opinions. However, a film has only one plot text, which is fair in tone and does not take a position. Despite its appealing properties and potential for accurate movie portrayal, the lack of a building block for effectively mining plot semantics has led to the marginalization of plot text in the design of movie recommendation algorithms. Therefore, in this paper, we explore the application of the Transformer, currently the best natural language processing module, to learning movie plot texts to help achieve more accurate rating prediction. We propose the "Plot-Aware Transformer" model (PAT) to model the process of "user-movie" rating interaction. We test the PAT model on several movie datasets and demonstrated that the model is competitive. In all tasks, PAT achieves state-of-the-art performance compared to baseline experiments.</p> </abstract>

Failure Analysis of Hadoop Schedulers using an Integration of Model Checking and Simulation

The Hadoop scheduler is a centerpiece of Hadoop, the leading processing framework for data-intensive applications in the cloud. Given the impact of failures on the performance of applications running on Hadoop, testing and verifying the performance of the Hadoop scheduler is critical. Existing approaches such as performance simulation and analytical modeling are inadequate because they are not able to ascertain a complete verification of a Hadoop scheduler. This is due to the wide range of constraints and aspects involved in Hadoop. In this paper, we propose a novel methodology that integrates and combines simulation and model checking techniques to perform a formal verification of Hadoop schedulers, focusing on the following properties: schedulability, fairness and resources-deadlock freeness. We use the CSP language to formally describe a Hadoop scheduler, and the PAT model checker to verify its properties. Next, we use the proposed formal model to analyze the scheduler of OpenCloud, a Hadoop-based cluster that simulates the Hadoop load, in order to illustrate the usability and benefits of our work. Results show that our proposed methodology can help identify several tasks failures (up to 78%) early on, i.e., before the tasks are executed on the cluster.

A Novel Prediction Model for Risk of Acute-on-Chronic Liver Failure in Chronic Hepatitis B Virus-Infected Patients With Flare of Hepatitis

Background: Chronic patients with flare of hepatitis B virus (HBV) may progress to acute-on-chronic liver failure (ACLF), which is characterized by high mortality. Uniform models to predict risk of ACLF are lacking. We aimed to present an accurate risk prediction model that incorporates clinical manifestations and laboratory results in chronic HBV-infected patients with flare of hepatitis. Methods: We selected the best variable combination using recursive feature elimination (RFE) from a perspective cohort including 360 patients with hepatitis flare at the Third Affiliated Hospital of Sun Yat-sen University to develop a risk prediction model and nomogram scoring system, then validated the model using two external independent sets consisting of 96 and 65 individuals, and compared its performance with End-Stage Liver Disease (MELD) score model. Findings: An excellent prediction model called the PAT model using the five final identified predictors including prothrombin time (PT), total bilirubin (TBil), ascites, pneumonia and hemoglobin (HGB) was constructed. The model could achieve an Area under the Receiver Operating Characteristic curve (AUROC) of 0.964 (95% confidence interval [CI]: 0.949-0.980) in the development set and performed well in external validation cohorts (validation cohort 1, AUROC = 0.909, 95% CI 0.840-0.977; validation cohort 2, AUROC = 0.898, 95% CI 0.813-0.983, both of which were significantly higher than the MELD score model (P <0.001). Interpretation: The easy-to-use PAT model can accurately predict the risk of ACLF risk in chronic hepatitis B patients with flare of hepatitis, which is expected to become a widely accepted prediction model and guide therapeutic options. Funding Statement: This work was supported by a grant for National Key RD National Natural Science Foundation of China (81773176); Science and Technology Program of Guangzhou (201804010474); the 5010 Project of Clinical Research in Sun Yat-sen University (2016009); Medical Scientific Research Foundation of Guangdong Province (A2017118); Major Science and Technology Projects in 13th Five-Year (2018ZX10715004-001-09); Natural Science Foundation of Guangdong (2018A030310272); Guangdong basic and Applied Basic Research Foundation (2019A1515110166) ; Guangdong Medical Science and Technology Research Fund (A2018366); 3rd Affiliated Hospital of Sun Yat-Sen University, Clinical Research Program (P000-277) and Meizhou Science and Technology Project (2019B0203003). Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: The study was approved by the institutional ethics committee of the Third Affiliated Hospital of Sun Yat-sen University.

Language Inclusion Checking of Timed Automata with Non-Zenoness

Given a timed automaton P modeling an implementation and a timed automaton S as a specification, the problem of language inclusion checking is to decide whether the language of P is a subset of that of S. It is known to be undecidable. The problem gets more complicated if non-Zenoness is taken into consideration. A run is Zeno if it permits infinitely many actions within finite time. Otherwise it is non-Zeno. Zeno runs might present in both P and S. It is necessary to check whether a run is Zeno or not so as to avoid presenting Zeno runs as counterexamples of language inclusion checking. In this work, we propose a zone-based semi-algorithm for language inclusion checking with non-Zenoness. It is further improved with simulation reduction based on LU-simulation. Though our approach is not guaranteed to terminate, we show that it does in many cases through empirical study. Our approach has been incorporated into the PAT model checker, and applied to multiple systems to show its usefulness.

An improved genetic algorithm for task scheduling in the cloud environments using the priority queues: Formal verification, simulation, and statistical testing

Abstract Cloud computing is a new platform to manage and provide services on the internet. Lately, researchers have paid attention a lot to this new subject. One of the reasons to have high performance in a cloud environment is the task scheduling. Since the task scheduling is an NP-Complete problem, in many cases, meta-heuristics scheduling algorithms are used. In this paper to optimize the task scheduling solutions, a powerful and improved genetic algorithm is proposed. The proposed algorithm uses the advantages of evolutionary genetic algorithm along with heuristic approaches. For analyzing the correctness of the proposed algorithm, we have presented a behavioral modeling approach based on model checking techniques. Then, the expected specifications of the proposed algorithm is extracted in the form of Linear Temporal Logic (LTL) formulas. To achieve the best performance in verification of the proposed algorithm, we use the Labeled Transition System (LTS) method. Also, the proposed behavioral models are verified using NuSMV and PAT model checkers. Then, the correctness of the proposed algorithm is analyzed according to the verification results in terms of some expected specifications, reachability, fairness, and deadlock-free. The simulation and statistical results revealed that the proposed algorithm outperformed the makespans of the three well-known heuristic algorithms and also the execution time of our recently meta-heuristics algorithm.

A Study of Climate Change Control Schemes: India's Pat Scheme with Other International Climate Change Control Schemes

The paper comprehensively reviews and compares the features of climate change control program of India (PAT - Perform Achieve and Trade) with that of global programmes. One of the significant findings of the paper is that India’s PAT model is unique and contains many features which are not present in many of global climate change control programmes. PAT is a market-based mechanism designed to trade energy savings certificates in contrast to an Exchange Traded Scheme (ETS) where emission reduction certificates are traded which operates on the principle of “Pay and Pollute”.

A New Integrated Model for Multitasking during Web Searching

There have been many studies in the field of information behavior. Recently Du and Spink (2011) presented a model, which simulates multitasking, cognitive coordination and cognitive shifts on web. However, this model does not incorporate personal variables and the impact of task or web design. This research addresses this gap. Information and psychological scientists have shown that information behavior (IR) is affected by: the affective domain, cognitive attributes, psychological factors, personality dimensions and sociological factors. This study investigates how IR is affected by working memory (wm), cognitive coordination, cognitive shifts and various artifacts and task variables influenced by the PAT model (Personal, Artifact and Task characteristics) of flow. The research is exploratory and takes a pragmatic, mixed method approach. Thirty University students will participate. The research tools include: pre and post questionnaires, working memory tests, Flow State Scale test, think aloud data, observations, audio-visual data, web search logs and use of the Critical Decision Method. The qualitative data will be coded and analyzed thematically and will be related to the quantitative data. This study is expected to identify the impact of all these variables on multitasking IR in the web and provide a new integrated framework, which is not only going to help information scientists to better understand this behavior but also web companies to develop more effective web products.

A formal semantics of extended hierarchical state transition matrices using CSP#

Abstract The extended hierarchical state transition matrices (EHSTMs) are a table-based modelling language frequently used in industry for specifying behaviours of systems. However, assuring correctness, i.e., having a design satisfy certain desired properties, is a non-trivial task. To address this problem, a model checker dedicated to EHSTMs called Garakabu2 has been developed. However, there is no formal justification for Garakabu2, since its semantics has never been fully formalised. In this paper, we give a formal semantics to EHSTMs by translating them into CSP, Communicating Sequential Processes. Among the variants of CSP, we use CSP#, which is the modelling language used by PAT model checker, as a target of translation. Our semantics covers most of the features supported by Garakabu2. We manually translate the small examples of EHSTMs to CSP#, and verify them by PAT. We also verify the examples directly using Garakabu2 and show that the results are same. The experiments also indicate that verification using our translation and PAT is much faster than that of Garakabu2 in some cases.

Using Model Checking to Verify the Logic Module of Flight Control Software

Model checking is an important method to verify state machine based system. In this paper, we using PAT, a novel and powerful model checking tool, to verify the logic module of flight control software, which is public available. Conclusions are drawn from the verification and these are valuable for similar researches.

Verifying Linearizability via Optimized Refinement Checking

Linearizability is an important correctness criterion for implementations of concurrent objects. Automatic checking of linearizability is challenging because it requires checking that: (1) All executions of concurrent operations are serializable, and (2) the serialized executions are correct with respect to the sequential semantics. In this work, we describe a method to automatically check linearizability based on refinement relations from abstract specifications to concrete implementations. The method does not require that linearization points in the implementations be given, which is often difficult or impossible. However, the method takes advantage of linearization points if they are given. The method is based on refinement checking of finite-state systems specified as concurrent processes with shared variables. To tackle state space explosion, we develop and apply symmetry reduction, dynamic partial order reduction, and a combination of both for refinement checking. We have built the method into the PAT model checker, and used PAT to automatically check a variety of implementations of concurrent objects, including the first algorithm for scalable nonzero indicators. Our system is able to find all known and injected bugs in these implementations.

Modeling and verifying hierarchical real-time systems using stateful timed CSP

Modeling and verifying complex real-time systems are challenging research problems. The de facto approach is based on Timed Automata, which are finite state automata equipped with clock variables. Timed Automata are deficient in modeling hierarchical complex systems. In this work, we propose a language called Stateful Timed CSP and an automated approach for verifying Stateful Timed CSP models. Stateful Timed CSP is based on Timed CSP and is capable of specifying hierarchical real-time systems. Through dynamic zone abstraction, finite-state zone graphs can be generated automatically from Stateful Timed CSP models, which are subject to model checking. Like Timed Automata, Stateful Timed CSP models suffer from Zeno runs, that is, system runs that take infinitely many steps within finite time. Unlike Timed Automata, model checking with non-Zenoness in Stateful Timed CSP can be achieved based on the zone graphs. We extend the PAT model checker to support system modeling and verification using Stateful Timed CSP and show its usability/scalability via verification of real-world systems.

A rift in modernity? assessing the anthropogenic sources of global climate change with the STIRPAT model

Ascientific consensus has emerged indicating that the global climate is changing due to anthropogenic (i.e., human induced) driving forces. Our previous research reformulated the well‐known I=PAT (environmental Impacts equal the multiplicative product of Population, Affluence, and Technology) model into stochastic form, named it the STIRPAT model, and used it to assess the effects of population and affluence on carbon dioxide loads. Here we extend those findings by examining the impacts of population, affluence and other factors on the emissions of the greenhouse gases (GHGs) methane (CH4) and carbon dioxide (CO2), as well as the combined global warming potential of these two gases. We also assess the potential for “ecological modernization” or an “environmental Kuznets curve” (EKC) effect to curb GHG emissions. Our findings suggest that population is a consistent force behind GHG emissions, that affluence also drives emissions, that urbanization and industrialization increase emissions, and that tropical nations have lower emissions than non‐tropical nations, controlling for other factors. Contrary to what ecological modernization and EKC theorists predict, we find that to date there is no compelling evidence of a decline in emissions with modernization. These results support both the “treadmill of production” thesis and the “metabolic rift” thesis.

Developmental Biology of the Axolotl

Part 1 Scientific and natural history: discovery of the axolotl and its early history in biological research, Hobart Smith natural history of the axolotl and its relationship to the salamander, Ronald Brandon. Part 2 Developmental biology: oogenesis, Jean-Claude Beetschen and Jean Gautier spermatogenesis, John Armstrong regulation of gene expression during early development, Jaques Signoret regional specification in early development, Jonathan Slack neurulation, Richard Gordon and Wayne Bordland morphogenetic waves during elongation, John Armstrong neural crest cell migration, Jan Lofberg et al developmental genetics, George Malacinski cell lethal genes, Anton Neff pigmentation and colour variants, Sally Frost the gene e (eyeless) - its effects on embryonic development, Robert Cuny and George Malacinski growth control in limb regeneration, Ken Muneoka et al neurobiology, William Harris the amazing mauthner cell, Pat Model the lateral line system, Michael Lannoo metamorphosis, E.R.Kunh and G.F.M.Jacobs. Part 3 Practical information on working with axolotls: developmental stage series of axolotl embryos, T.A.Dettlaff et al raising the axolotl in captivity, John Armstrong et al induced spawnings, artificial insemination and other genetic manipulations, John Armstrong and Susan Duhon genetic markers and their use with chimeras, John Armstrong and Ken Muneoka primary and long-term culture of axolotl cells, Sally Frost et al surgical manipulation of embryos, George Malacinski et al. Appendix: directory of axolotl colonies, George Malacinski and David Able.