Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC), 2015
Three dimensional (3D) mapping of environments has gained significant research interest over the ... more Three dimensional (3D) mapping of environments has gained significant research interest over the last decades because of its important need for environmental modeling and monitoring. There are many successful research efforts in this field, and even it has been turned into commercial products such as Velodyne Lidar [1]. However, due to natural localization challenges, not much research for 3D mapping wearable sensor devices has been successfully reported. In this paper, we are interested in building a smart and wearable shoe which integrates multiple laser scanners and an inertial measurement unit (IMU) to build a 3D map of the environments. The proposed Smart Shoe can collect data and build a real-time 3D map during human walking. Such a smart shoe can support disabled people (blind people) to easily navigate and avoid obstacles in the environment. Additionally, this shoe can help firefighters quickly model and recognize objects in the fired and dark smoke buildings where the cameras may not be useful. The developed localization algorithm using IMU can output a smooth and accurate pose and trajectory of the human walking. This key importance of the shoe localization enables 3D mapping successfully while minimizing data registration error from the laser point cloud.
Accurate recovery of predicate-argument dependencies is vital for interpretation tasks like infor... more Accurate recovery of predicate-argument dependencies is vital for interpretation tasks like information extraction and question answering, and unbounded dependencies may account for a significant portion of the dependencies in any given text. This paper describes a categorial grammar which, like other categorial grammars, imposes a small, uniform, and easily learnable set of semantic composition operations based on functor-argument relations, but like HPSG, is generalized to limit the number of categories used to those needed to enforce grammatical constraints. The paper also describes a novel reannotation system used to map existing resources based on Government and Binding Theory, like the Penn Treebank, into this categorial representation. This grammar is evaluated on an existing unbounded dependency recovery task (Rimell et al., 2009; Nivre et al., 2010).
Reading experiments using naturalistic stimuli have shown unanticipated facilitations for complet... more Reading experiments using naturalistic stimuli have shown unanticipated facilitations for completing center embeddings when frequency e ects are factored out. To eliminate possible confounds due to surface structure, this paper introduces a processing model based on deep syntactic dependencies. Results on eye-tracking data indicate that completing deep syntactic embeddings yields significantly more facilitation than completing surface embeddings.
Modern cyber-physical microgrids rely on the information exchanged among power electronics device... more Modern cyber-physical microgrids rely on the information exchanged among power electronics devices (i.e., converters or inverters with local embedded controllers) making them vulnerable to cyber manipulations. The physical devices themselves are susceptible to potential faults and failures. Effects of these cyber and physical anomalies can propagate throughout the entire microgrid due to information exchanged and the inherent low inertia of the distribution network. This work employs the parametric time-frequency logic (PTFL) framework to detect such cyber-physical anomalies. PTFL is a formalism to analyze the time-frequency content of the observable quantities of interest (such as current, voltage, or frequency) of power electronics devices in comparison with the predefined time-frequency properties. PTFL formalism is presented to detect the anomalies such as false data-injection attacks, denial-of-service attacks, and faults on a cluster of four DC microgrids and an inverter-populated IEEE 34-bus feeder system in a controller/hardware-in-the-loop environment. INDEX TERMS Distributed control, formal methods, microgrid, parametric time-frequency logic. OMAR ALI BEG (Member, IEEE) received the Ph.D. degree in electrical engineering from The
Proceedings of the 15th ACM-IEEE International Conference on Formal Methods and Models for System Design, 2017
A hyperproperty is a property that requires two or more execution traces to check. is is in contr... more A hyperproperty is a property that requires two or more execution traces to check. is is in contrast to properties expressed using temporal logics such as LTL, MTL and STL, which can be checked over individual traces. Hyperproperties are important as they are used to specify critical system performance objectives, such as those related to security, stochastic (or average) performance, and relationships between behaviors. We present the rst study of hyperproperties of cyber-physical systems (CPSs). We introduce a new formalism for specifying a class of hyperproperties de ned over real-valued signals, called HyperSTL. e proposed logic extends signal temporal logic (STL) by adding existential and universal trace quanti ers into STL's syntax to relate multiple execution traces. Several instances of hyperproperties of CPSs including stability, security, and safety are studied and expressed in terms of HyperSTL formulae. Furthermore, we propose a testing technique that allows us to check or falsify hyperproperties of CPS models. We present a discussion on the feasibility of falsifying or verifying various classes of hyperproperties for CPSs. We extend the quantitative semantics of STL to HyperSTL and show its utility in formulating algorithms for falsi cation of HyperSTL speci cations. We demonstrate how we can specify and falsify HyperSTL properties for two case studies involving automotive control systems.
Civil infrastructure inspection is crucial to maintaining the quality of that infrastructure, whi... more Civil infrastructure inspection is crucial to maintaining the quality of that infrastructure, which has a great impact on the economy. Performing this inspection is costly work that requires workers to be trained on how to use varying technologies, which can be error prone when performed manually and can result in damage to the infrastructure in some cases. For this reason, nondestructive evaluation (NDE) sensors are preferred for civil infrastructure inspection as they can perform the necessary inspection without damaging the infrastructure. In this paper, we develop a fully autonomous robotic system capable of real-time data collection and quasi-real-time data processing. The robotic system is equipped with several NDE sensors that allow for a sensor fusion method to be developed that successfully minimizes inspection time while performing adequate inspection of areas that require more in-depth data to be collected. A detailed discussion of the inspection framework developed for this robotic system, and the dual navigation modes for both indoor and outdoor autonomous navigation is presented. The developed robotic system is deployed to inspect several infrastructures (e.g., parking garages, bridges) at and near by the
2016 IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems (MFI), 2016
The intelligent power wheelchair (iChair) is designed to assist people with mobility, sensory, an... more The intelligent power wheelchair (iChair) is designed to assist people with mobility, sensory, and cognitive impairment lead a higher quality, more independent lifestyle. The iChair includes a power wheelchair (PW), laptop computer, laptop mount, multi-modal input platform, and a custom plastic enclosure for the environmental sensors, made with a 3D printer. We have developed the configuration of sensors to facilitate scientific observation, while maintaining the flexibility to mount the system on almost any power wheelchair, and remain easily removed for maintenance or travel. The first scientific observations have been used to compile ACCESS Reports that quantify a location or event's level of accessibility. If barriers exist we collect a 3D point cloud to be used as evidence and to make recommendations on how to remedy the problem. The iChair will serve a wide variety of disability types by incorporating several input methods, voice, touch, proximity switch, and head tracking camera. The HD camera and 3D scanner have been mounted in such a way as to provide reliable data with the precision necessary to detect obstacles, build 3D maps, follow guides, anticipate events, and provide navigational assistance. We evaluate the human factors in the current prototype to ensure that the technology will be accepted by those it is designed to serve, and propose a wheelchair skills test for future trial participants.
Asian Mountain Toads (Ophryophryne) are a poorly known genus of mostly small-sized anurans from s... more Asian Mountain Toads (Ophryophryne) are a poorly known genus of mostly small-sized anurans from southeastern China and Indochina. To shed light on the systematics within this group, the most com
Heterogeneous catalysis occurs at the interface of a solid catalyst and reactants. The structure ... more Heterogeneous catalysis occurs at the interface of a solid catalyst and reactants. The structure of metal catalyst nanoparticles at the metal-gas interface is a key factor that determines catalytic selectivity and activity. Here we report that second-generation nanoclusters are formed on the surfaces of the initial catalyst nanoparticles as a result of interaction with the reactant molecules when these metal nanoparticles are in a gas phase at Torr pressure or higher at room temperature. The formation of the second-generation nanoclusters is manifested by a decrease of the average coordination number of the metal atoms of the nanoparticles and a shift of the core level energy of metal atoms of metal nanoparticle surfaces tracked in gas phases. The formation of second-generation nanoclusters increases the number of under-coordinated sites, which are the most active for catalysis in many cases.
In this paper, we present the first steps toward a runtime verification framework for monitoring ... more In this paper, we present the first steps toward a runtime verification framework for monitoring hybrid and cyber-physical systems (CPS) development tools based on randomized differential testing. The development tools include hybrid systems reachability analysis tools, model-based development environments like Simulink/Stateflow (SLSF), etc. First, hybrid automaton models are randomly generated. Next, these hybrid automaton models are translated to a number of different tools (currently, SpaceEx, dReach, Flow*, HyCreate, and the MathWorks' Simulink/Stateflow) using the HyST source transformation and translation tool. Then, the hybrid automaton models are executed in the different tools and their outputs are parsed. The final step is the differential comparison: the outputs of the different tools are compared. If the results do not agree (in the sense that an analysis or verification result from one tool does not match that of another tool, ignoring timeouts, etc.), a candidate bug is flagged and the model is saved for future analysis by the user. The process then repeats and the monitoring continues until the user terminates the process. We present preliminary results that have been useful in identifying a few bugs in the analysis methods of different development tools, and in an earlier version of HyST.
A catalytic site typically consists of one or more atoms of a catalyst surface that arrange into ... more A catalytic site typically consists of one or more atoms of a catalyst surface that arrange into a configuration offering a specific electronic structure for adsorbing or dissociating reactant molecules. The catalytic activity of adjacent bimetallic sites of metallic nanoparticles has been studied previously. An isolated bimetallic site supported on a non-metallic surface could exhibit a distinctly different catalytic performance owing to the cationic state of the singly dispersed bimetallic site and the minimized choices of binding configurations of a reactant molecule compared with continuously packed bimetallic sites. Here we report that isolated Rh1Co3 bimetallic sites exhibit a distinctly different catalytic performance in reduction of nitric oxide with carbon monoxide at low temperature, resulting from strong adsorption of two nitric oxide molecules and a nitrous oxide intermediate on Rh1Co3 sites and following a low-barrier pathway dissociation to dinitrogen and an oxygen ato...
In this paper, we present the virtual prototyping of a solar array with a grid-tie implemented as... more In this paper, we present the virtual prototyping of a solar array with a grid-tie implemented as a distributed inverter and controlled using distributed algorithms. Due to the distributed control and inherent redundancy in the array composed of many panels and inverter modules, the virtual prototype exhibits fault-tolerance capabilities. The distributed identifier algorithm allows the system to keep track of the number of operating panels to appropriately regulate the DC voltage output of the panels using buck-boost converters, and determine appropriate switching times for H-bridges in the grid-tie. We evaluate the distributed inverter, its control strategy, and faulttolerance through simulation in Simulink/Stateflow. Our virtual prototyping framework allows for generating arrays and gridties consisting of many panels, and we evaluate arrays of five to dozens of panels. Our analysis suggests the achievable total harmonic distortion (THD) of the system may allow for operating the array in spite of failures of the power electronics, control software, and other subcomponents. Index Terms-distributed control, multilevel inverter, distributed inverter, solar array.
Proceedings of the ACL-IJCNLP 2009 Conference Short Papers on - ACL-IJCNLP '09, 2009
This paper describes a parsing model for speech with repairs that makes a clear separation betwee... more This paper describes a parsing model for speech with repairs that makes a clear separation between linguistically meaningful symbols in the grammar and operations specific to speech repair in the operation of the parser. This system builds a model of how unfinished constituents in speech repairs are likely to finish, and finishes them probabilistically with placeholder structure. These modified repair constituents and the restarted replacement constituent are then recognized together in the same way that two coordinated phrases of the same type are recognized.
In this paper, we present virtual prototyping of the distributed control for a modular multilevel... more In this paper, we present virtual prototyping of the distributed control for a modular multilevel inverter used as a grid-tie interface for photovoltaics. Due to the distributed control and inherent redundancy in the system composed of many panels and inverter modules, the system topology exhibits fault-tolerance capabilities that we study through virtual prototyping. The faulttolerance is enable by several distributed algorithms, such as services to identify which if any agents controlling inverter modules have failed. A distributed identifier algorithm allows the system to keep track of the number of operating panels to appropriately regulate the DC voltage output of the panels using buck-boost converters, and determine appropriate switching times for Hbridges in the grid-tie. We evaluate the distributed inverter, its control strategy, and fault-tolerance through thousand of simulation scenarios in Mathworks Simulink/Stateflow. Our virtual prototyping framework allows for generating multilevel inverters composed of many inverter modules, and we evaluate inverters composed of five to dozens of inverter modules. Our analysis suggests the achievable total harmonic distortion (THD) of the modular multilevel inverter may allow for operating solar arrays in spite of failures of the power electronics, control software, and other subcomponents. Index Terms-distributed control, multilevel inverter, distributed inverter, hybrid systems.
Species of bent-toed gecko (Cyrtodactylus) in Vietnam have been described at a rate of nearly fou... more Species of bent-toed gecko (Cyrtodactylus) in Vietnam have been described at a rate of nearly four species per year since 2007 mostly based on morphological data. A tool that guides species delimitation will accelerate the rate of documentation, and at a time when the recognition of species greatly benefits conservation. We use DNA barcoding using COI (550 bp) to reexamine the levels of genetic divergence and taxonomic status of 21 described species of Vietnamese bent-toed geckos. Tree-based analyses resolve all sampled species and identify potential undescribed taxa. Kimura 2-parameter genetic distances between the described species average 21.0±4.2% and range from 4.3% to 28.7%. Further, our analyses discover two potentially new species from Vietnam, two from Laos and one from China. Herein we describe the new species Cyrtodactylus puhuensis sp. nov. from Vietnam on the basis of both genetics and morphology. Genetically, it differs from the remaining species by an average K2P distance of 24.0±1.8%. Morphologically, the new species is diagnosed by its medium-size (snout-vent length 79.24 mm and tail length 82.59 mm, for the single known individual), in having a series of moderately enlarged transverse subcaudals and a series of moderately enlarged femoral scales that extend from precloacal scales, in possessing femoral scales without pores, with males having five precloacal pores, and in exhibiting 8 supralabials, 10 infralabials, 23 narrow subdigital lamellae on its fourth toe, and 36 transverse ventrals.
The number of described species of bent-toed geckos of the Cyrtodactylus irregularis species comp... more The number of described species of bent-toed geckos of the Cyrtodactylus irregularis species complex in Vietnam has increased from one to eight in the last six years. We combined morphological and molecular analyses to explore phylogenetic relationships among all described species in the group. The phylogeny required the description of two new species, Cyrtodactylus phuocbinhensis sp. nov. and Cyrtodactylus taynguyenensis sp. nov. Further, the tree resolved two additional undescribed clades that may also be new species. The species C. bugiamapensis and C. ziegleri were found to require redefinition. Cyrtodactylus phuocbinhensis sp. nov. is characterized by a series of enlarged femoral scales separated from preanal scales while Cyrtodactylus taynguyenensis sp. nov. does not possess enlarged femoral scales. Both new species are distinguished from other congeners by a combination of the following characters: small subcaudal scales, not transversely enlarged; presence (C. phuocbinhensis sp. nov.) or absence (C. taynguyenensis sp. nov.) of enlarged femoral scales; number of preanal pores; and dorsal pattern. Genetic distances between described species and new species were 16.5% and 2.0% in COI and RPL35, respectively, for C. phuocbinhensis sp. nov., and these distances were 18.8% and 2.2% for C. taynguyenensis sp. nov., respectively.
Proceedings of the 15th International Workshop on Semantic Evaluation (SemEval-2021)
The increment of toxic comments on online space is causing tremendous effects on other vulnerable... more The increment of toxic comments on online space is causing tremendous effects on other vulnerable users. For this reason, considerable efforts are made to deal with this, and SemEval-2021 Task 5: Toxic Spans Detection is one of those. This task asks competitors to extract spans that have toxicity from the given texts, and we have done several analyses to understand its structure before doing experiments. We solve this task by two approaches, Named Entity Recognition with spaCy's library and Question-Answering with RoBERTa combining with ToxicBERT, and the former gains the highest F1-score of 66.99%.
Proceedings of the 14th international conference on Intelligent user interfaces, 2009
Spoken language interfaces based on interactive semantic language models [16, 14] allow probabili... more Spoken language interfaces based on interactive semantic language models [16, 14] allow probabilities for hypothesized words to be conditioned on the semantic interpretation of these words in the context of some interfaced application environment. This conditioning may allow users to avoid recognition errors in an intuitive way, by adding extra, possibly redundant description. This paper evaluates the effect on error reduction of redundant descriptions in an interactive semantic language model. In order to evaluate the effect in natural use, the model is run on rich domains, supporting references to sets of individuals (instead of just individuals themselves) arranged in multiple continuous dimensions (a 2-D floorplan scene). Results of these experiments suggest that an interactive semantic language model allows users to achieve significantly higher recognition accuracy by providing additional redundant spoken description.
Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC), 2015
Three dimensional (3D) mapping of environments has gained significant research interest over the ... more Three dimensional (3D) mapping of environments has gained significant research interest over the last decades because of its important need for environmental modeling and monitoring. There are many successful research efforts in this field, and even it has been turned into commercial products such as Velodyne Lidar [1]. However, due to natural localization challenges, not much research for 3D mapping wearable sensor devices has been successfully reported. In this paper, we are interested in building a smart and wearable shoe which integrates multiple laser scanners and an inertial measurement unit (IMU) to build a 3D map of the environments. The proposed Smart Shoe can collect data and build a real-time 3D map during human walking. Such a smart shoe can support disabled people (blind people) to easily navigate and avoid obstacles in the environment. Additionally, this shoe can help firefighters quickly model and recognize objects in the fired and dark smoke buildings where the cameras may not be useful. The developed localization algorithm using IMU can output a smooth and accurate pose and trajectory of the human walking. This key importance of the shoe localization enables 3D mapping successfully while minimizing data registration error from the laser point cloud.
Accurate recovery of predicate-argument dependencies is vital for interpretation tasks like infor... more Accurate recovery of predicate-argument dependencies is vital for interpretation tasks like information extraction and question answering, and unbounded dependencies may account for a significant portion of the dependencies in any given text. This paper describes a categorial grammar which, like other categorial grammars, imposes a small, uniform, and easily learnable set of semantic composition operations based on functor-argument relations, but like HPSG, is generalized to limit the number of categories used to those needed to enforce grammatical constraints. The paper also describes a novel reannotation system used to map existing resources based on Government and Binding Theory, like the Penn Treebank, into this categorial representation. This grammar is evaluated on an existing unbounded dependency recovery task (Rimell et al., 2009; Nivre et al., 2010).
Reading experiments using naturalistic stimuli have shown unanticipated facilitations for complet... more Reading experiments using naturalistic stimuli have shown unanticipated facilitations for completing center embeddings when frequency e ects are factored out. To eliminate possible confounds due to surface structure, this paper introduces a processing model based on deep syntactic dependencies. Results on eye-tracking data indicate that completing deep syntactic embeddings yields significantly more facilitation than completing surface embeddings.
Modern cyber-physical microgrids rely on the information exchanged among power electronics device... more Modern cyber-physical microgrids rely on the information exchanged among power electronics devices (i.e., converters or inverters with local embedded controllers) making them vulnerable to cyber manipulations. The physical devices themselves are susceptible to potential faults and failures. Effects of these cyber and physical anomalies can propagate throughout the entire microgrid due to information exchanged and the inherent low inertia of the distribution network. This work employs the parametric time-frequency logic (PTFL) framework to detect such cyber-physical anomalies. PTFL is a formalism to analyze the time-frequency content of the observable quantities of interest (such as current, voltage, or frequency) of power electronics devices in comparison with the predefined time-frequency properties. PTFL formalism is presented to detect the anomalies such as false data-injection attacks, denial-of-service attacks, and faults on a cluster of four DC microgrids and an inverter-populated IEEE 34-bus feeder system in a controller/hardware-in-the-loop environment. INDEX TERMS Distributed control, formal methods, microgrid, parametric time-frequency logic. OMAR ALI BEG (Member, IEEE) received the Ph.D. degree in electrical engineering from The
Proceedings of the 15th ACM-IEEE International Conference on Formal Methods and Models for System Design, 2017
A hyperproperty is a property that requires two or more execution traces to check. is is in contr... more A hyperproperty is a property that requires two or more execution traces to check. is is in contrast to properties expressed using temporal logics such as LTL, MTL and STL, which can be checked over individual traces. Hyperproperties are important as they are used to specify critical system performance objectives, such as those related to security, stochastic (or average) performance, and relationships between behaviors. We present the rst study of hyperproperties of cyber-physical systems (CPSs). We introduce a new formalism for specifying a class of hyperproperties de ned over real-valued signals, called HyperSTL. e proposed logic extends signal temporal logic (STL) by adding existential and universal trace quanti ers into STL's syntax to relate multiple execution traces. Several instances of hyperproperties of CPSs including stability, security, and safety are studied and expressed in terms of HyperSTL formulae. Furthermore, we propose a testing technique that allows us to check or falsify hyperproperties of CPS models. We present a discussion on the feasibility of falsifying or verifying various classes of hyperproperties for CPSs. We extend the quantitative semantics of STL to HyperSTL and show its utility in formulating algorithms for falsi cation of HyperSTL speci cations. We demonstrate how we can specify and falsify HyperSTL properties for two case studies involving automotive control systems.
Civil infrastructure inspection is crucial to maintaining the quality of that infrastructure, whi... more Civil infrastructure inspection is crucial to maintaining the quality of that infrastructure, which has a great impact on the economy. Performing this inspection is costly work that requires workers to be trained on how to use varying technologies, which can be error prone when performed manually and can result in damage to the infrastructure in some cases. For this reason, nondestructive evaluation (NDE) sensors are preferred for civil infrastructure inspection as they can perform the necessary inspection without damaging the infrastructure. In this paper, we develop a fully autonomous robotic system capable of real-time data collection and quasi-real-time data processing. The robotic system is equipped with several NDE sensors that allow for a sensor fusion method to be developed that successfully minimizes inspection time while performing adequate inspection of areas that require more in-depth data to be collected. A detailed discussion of the inspection framework developed for this robotic system, and the dual navigation modes for both indoor and outdoor autonomous navigation is presented. The developed robotic system is deployed to inspect several infrastructures (e.g., parking garages, bridges) at and near by the
2016 IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems (MFI), 2016
The intelligent power wheelchair (iChair) is designed to assist people with mobility, sensory, an... more The intelligent power wheelchair (iChair) is designed to assist people with mobility, sensory, and cognitive impairment lead a higher quality, more independent lifestyle. The iChair includes a power wheelchair (PW), laptop computer, laptop mount, multi-modal input platform, and a custom plastic enclosure for the environmental sensors, made with a 3D printer. We have developed the configuration of sensors to facilitate scientific observation, while maintaining the flexibility to mount the system on almost any power wheelchair, and remain easily removed for maintenance or travel. The first scientific observations have been used to compile ACCESS Reports that quantify a location or event's level of accessibility. If barriers exist we collect a 3D point cloud to be used as evidence and to make recommendations on how to remedy the problem. The iChair will serve a wide variety of disability types by incorporating several input methods, voice, touch, proximity switch, and head tracking camera. The HD camera and 3D scanner have been mounted in such a way as to provide reliable data with the precision necessary to detect obstacles, build 3D maps, follow guides, anticipate events, and provide navigational assistance. We evaluate the human factors in the current prototype to ensure that the technology will be accepted by those it is designed to serve, and propose a wheelchair skills test for future trial participants.
Asian Mountain Toads (Ophryophryne) are a poorly known genus of mostly small-sized anurans from s... more Asian Mountain Toads (Ophryophryne) are a poorly known genus of mostly small-sized anurans from southeastern China and Indochina. To shed light on the systematics within this group, the most com
Heterogeneous catalysis occurs at the interface of a solid catalyst and reactants. The structure ... more Heterogeneous catalysis occurs at the interface of a solid catalyst and reactants. The structure of metal catalyst nanoparticles at the metal-gas interface is a key factor that determines catalytic selectivity and activity. Here we report that second-generation nanoclusters are formed on the surfaces of the initial catalyst nanoparticles as a result of interaction with the reactant molecules when these metal nanoparticles are in a gas phase at Torr pressure or higher at room temperature. The formation of the second-generation nanoclusters is manifested by a decrease of the average coordination number of the metal atoms of the nanoparticles and a shift of the core level energy of metal atoms of metal nanoparticle surfaces tracked in gas phases. The formation of second-generation nanoclusters increases the number of under-coordinated sites, which are the most active for catalysis in many cases.
In this paper, we present the first steps toward a runtime verification framework for monitoring ... more In this paper, we present the first steps toward a runtime verification framework for monitoring hybrid and cyber-physical systems (CPS) development tools based on randomized differential testing. The development tools include hybrid systems reachability analysis tools, model-based development environments like Simulink/Stateflow (SLSF), etc. First, hybrid automaton models are randomly generated. Next, these hybrid automaton models are translated to a number of different tools (currently, SpaceEx, dReach, Flow*, HyCreate, and the MathWorks' Simulink/Stateflow) using the HyST source transformation and translation tool. Then, the hybrid automaton models are executed in the different tools and their outputs are parsed. The final step is the differential comparison: the outputs of the different tools are compared. If the results do not agree (in the sense that an analysis or verification result from one tool does not match that of another tool, ignoring timeouts, etc.), a candidate bug is flagged and the model is saved for future analysis by the user. The process then repeats and the monitoring continues until the user terminates the process. We present preliminary results that have been useful in identifying a few bugs in the analysis methods of different development tools, and in an earlier version of HyST.
A catalytic site typically consists of one or more atoms of a catalyst surface that arrange into ... more A catalytic site typically consists of one or more atoms of a catalyst surface that arrange into a configuration offering a specific electronic structure for adsorbing or dissociating reactant molecules. The catalytic activity of adjacent bimetallic sites of metallic nanoparticles has been studied previously. An isolated bimetallic site supported on a non-metallic surface could exhibit a distinctly different catalytic performance owing to the cationic state of the singly dispersed bimetallic site and the minimized choices of binding configurations of a reactant molecule compared with continuously packed bimetallic sites. Here we report that isolated Rh1Co3 bimetallic sites exhibit a distinctly different catalytic performance in reduction of nitric oxide with carbon monoxide at low temperature, resulting from strong adsorption of two nitric oxide molecules and a nitrous oxide intermediate on Rh1Co3 sites and following a low-barrier pathway dissociation to dinitrogen and an oxygen ato...
In this paper, we present the virtual prototyping of a solar array with a grid-tie implemented as... more In this paper, we present the virtual prototyping of a solar array with a grid-tie implemented as a distributed inverter and controlled using distributed algorithms. Due to the distributed control and inherent redundancy in the array composed of many panels and inverter modules, the virtual prototype exhibits fault-tolerance capabilities. The distributed identifier algorithm allows the system to keep track of the number of operating panels to appropriately regulate the DC voltage output of the panels using buck-boost converters, and determine appropriate switching times for H-bridges in the grid-tie. We evaluate the distributed inverter, its control strategy, and faulttolerance through simulation in Simulink/Stateflow. Our virtual prototyping framework allows for generating arrays and gridties consisting of many panels, and we evaluate arrays of five to dozens of panels. Our analysis suggests the achievable total harmonic distortion (THD) of the system may allow for operating the array in spite of failures of the power electronics, control software, and other subcomponents. Index Terms-distributed control, multilevel inverter, distributed inverter, solar array.
Proceedings of the ACL-IJCNLP 2009 Conference Short Papers on - ACL-IJCNLP '09, 2009
This paper describes a parsing model for speech with repairs that makes a clear separation betwee... more This paper describes a parsing model for speech with repairs that makes a clear separation between linguistically meaningful symbols in the grammar and operations specific to speech repair in the operation of the parser. This system builds a model of how unfinished constituents in speech repairs are likely to finish, and finishes them probabilistically with placeholder structure. These modified repair constituents and the restarted replacement constituent are then recognized together in the same way that two coordinated phrases of the same type are recognized.
In this paper, we present virtual prototyping of the distributed control for a modular multilevel... more In this paper, we present virtual prototyping of the distributed control for a modular multilevel inverter used as a grid-tie interface for photovoltaics. Due to the distributed control and inherent redundancy in the system composed of many panels and inverter modules, the system topology exhibits fault-tolerance capabilities that we study through virtual prototyping. The faulttolerance is enable by several distributed algorithms, such as services to identify which if any agents controlling inverter modules have failed. A distributed identifier algorithm allows the system to keep track of the number of operating panels to appropriately regulate the DC voltage output of the panels using buck-boost converters, and determine appropriate switching times for Hbridges in the grid-tie. We evaluate the distributed inverter, its control strategy, and fault-tolerance through thousand of simulation scenarios in Mathworks Simulink/Stateflow. Our virtual prototyping framework allows for generating multilevel inverters composed of many inverter modules, and we evaluate inverters composed of five to dozens of inverter modules. Our analysis suggests the achievable total harmonic distortion (THD) of the modular multilevel inverter may allow for operating solar arrays in spite of failures of the power electronics, control software, and other subcomponents. Index Terms-distributed control, multilevel inverter, distributed inverter, hybrid systems.
Species of bent-toed gecko (Cyrtodactylus) in Vietnam have been described at a rate of nearly fou... more Species of bent-toed gecko (Cyrtodactylus) in Vietnam have been described at a rate of nearly four species per year since 2007 mostly based on morphological data. A tool that guides species delimitation will accelerate the rate of documentation, and at a time when the recognition of species greatly benefits conservation. We use DNA barcoding using COI (550 bp) to reexamine the levels of genetic divergence and taxonomic status of 21 described species of Vietnamese bent-toed geckos. Tree-based analyses resolve all sampled species and identify potential undescribed taxa. Kimura 2-parameter genetic distances between the described species average 21.0±4.2% and range from 4.3% to 28.7%. Further, our analyses discover two potentially new species from Vietnam, two from Laos and one from China. Herein we describe the new species Cyrtodactylus puhuensis sp. nov. from Vietnam on the basis of both genetics and morphology. Genetically, it differs from the remaining species by an average K2P distance of 24.0±1.8%. Morphologically, the new species is diagnosed by its medium-size (snout-vent length 79.24 mm and tail length 82.59 mm, for the single known individual), in having a series of moderately enlarged transverse subcaudals and a series of moderately enlarged femoral scales that extend from precloacal scales, in possessing femoral scales without pores, with males having five precloacal pores, and in exhibiting 8 supralabials, 10 infralabials, 23 narrow subdigital lamellae on its fourth toe, and 36 transverse ventrals.
The number of described species of bent-toed geckos of the Cyrtodactylus irregularis species comp... more The number of described species of bent-toed geckos of the Cyrtodactylus irregularis species complex in Vietnam has increased from one to eight in the last six years. We combined morphological and molecular analyses to explore phylogenetic relationships among all described species in the group. The phylogeny required the description of two new species, Cyrtodactylus phuocbinhensis sp. nov. and Cyrtodactylus taynguyenensis sp. nov. Further, the tree resolved two additional undescribed clades that may also be new species. The species C. bugiamapensis and C. ziegleri were found to require redefinition. Cyrtodactylus phuocbinhensis sp. nov. is characterized by a series of enlarged femoral scales separated from preanal scales while Cyrtodactylus taynguyenensis sp. nov. does not possess enlarged femoral scales. Both new species are distinguished from other congeners by a combination of the following characters: small subcaudal scales, not transversely enlarged; presence (C. phuocbinhensis sp. nov.) or absence (C. taynguyenensis sp. nov.) of enlarged femoral scales; number of preanal pores; and dorsal pattern. Genetic distances between described species and new species were 16.5% and 2.0% in COI and RPL35, respectively, for C. phuocbinhensis sp. nov., and these distances were 18.8% and 2.2% for C. taynguyenensis sp. nov., respectively.
Proceedings of the 15th International Workshop on Semantic Evaluation (SemEval-2021)
The increment of toxic comments on online space is causing tremendous effects on other vulnerable... more The increment of toxic comments on online space is causing tremendous effects on other vulnerable users. For this reason, considerable efforts are made to deal with this, and SemEval-2021 Task 5: Toxic Spans Detection is one of those. This task asks competitors to extract spans that have toxicity from the given texts, and we have done several analyses to understand its structure before doing experiments. We solve this task by two approaches, Named Entity Recognition with spaCy's library and Question-Answering with RoBERTa combining with ToxicBERT, and the former gains the highest F1-score of 66.99%.
Proceedings of the 14th international conference on Intelligent user interfaces, 2009
Spoken language interfaces based on interactive semantic language models [16, 14] allow probabili... more Spoken language interfaces based on interactive semantic language models [16, 14] allow probabilities for hypothesized words to be conditioned on the semantic interpretation of these words in the context of some interfaced application environment. This conditioning may allow users to avoid recognition errors in an intuitive way, by adding extra, possibly redundant description. This paper evaluates the effect on error reduction of redundant descriptions in an interactive semantic language model. In order to evaluate the effect in natural use, the model is run on rich domains, supporting references to sets of individuals (instead of just individuals themselves) arranged in multiple continuous dimensions (a 2-D floorplan scene). Results of these experiments suggest that an interactive semantic language model allows users to achieve significantly higher recognition accuracy by providing additional redundant spoken description.
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Papers by Luan Nguyen