Proceedings of the eighteenth annual ACM symposium on Parallelism in algorithms and architectures - SPAA '06, 2006
Tree contraction algorithms, whose idea was first proposed by Miller and Reif, are important para... more Tree contraction algorithms, whose idea was first proposed by Miller and Reif, are important parallel algorithms to implement efficient parallel programs manipulating trees. Despite their efficiency, the tree contraction algorithms have not been widely used due to the difficulties in deriving the tree contracting operations. In particular, the derivation of the tree contracting operations is much difficult when multiple values are referred and updated in each step of the contractions. Such computations often appear in dynamic programming problems on trees.
International Journal of Parallel Programming, 2007
Computations on two-dimensional arrays such as matrix computations are one of the most fundamenta... more Computations on two-dimensional arrays such as matrix computations are one of the most fundamental and ubiquitous in computational science and its vast application areas, but development of efficient parallel programs on two-dimensional arrays is known to be hard. In this paper, we propose a compositional framework which supports users, even with little knowledge about parallel machines, to systematically develop both correct and efficient parallel programs on two-dimensional arrays. The key feature of our framework is a novel use of the abide-tree representation of two-dimensional arrays, which not only inherits the advantages of tree representations of matrix where recursive blocked algorithms can be defined to achieve better performance, but also supports transformational development of parallel programs and architecture independent implementation owing to its solid theoretical foundation -the theory of constructive algorithmics.
Trees are useful data structures, but to design efficient parallel programs over trees is known t... more Trees are useful data structures, but to design efficient parallel programs over trees is known to be more difficult than to do over lists. Although several important tree skeletons have been proposed to simplify parallel programming on trees, few studies have been reported on how to systematically use them in solving practical problems; it is neither clear how to make a good combination of skeletons to solve a given problem, nor obvious how to find suitable operators used in a single skeleton. In this paper, we report our first attempt to resolve these problems, proposing two important transformations, the tree diffusion transformation and the tree context preservation transformation. The tree diffusion transformation allows one to use familiar recursive definitions to develop his parallel programs, while the tree context preservation transformation shows how to derive associative operators that are required when using tree skeletons. We illustrate our approach by deriving an efficient parallel program for solving a nontrivial problem called the party planning problem, the tree version of the famous maximum-weight-sum problem.
ABSTRACT We present a new derivation of efficient algorithms for a class of optimization problems... more ABSTRACT We present a new derivation of efficient algorithms for a class of optimization problems called maximum marking problems. We extend the class of weight functions used in the specification to allow for weight functions with accumulation, which is particularly useful when the weight of each element depends on adjacent elements. This extension of weight functions enables us to treat more interesting optimization problems such as a variant of the maximum segment sum problem and the fair bonus distribution problem. The complexity of the derived algorithm is linear with respect to the size of the input data.
Proceedings of the 2009 Acm Symposium on Applied Computing, 2009
Model transformation plays an important role in model-driven software development that aims to in... more Model transformation plays an important role in model-driven software development that aims to introduce significant efficiencies and rigor to the theory and practice of software development. Although models may have different notations and representations, they are basically graphs, and model transformations are thus nothing but graph transformations. Despite a large amount of theoretical work and a lot of experience with research prototypes on graph-based model transformations, it remains an open issue how to compose model transformations. In this paper, we report our first attempt at a compositional framework for graph-based model transformations using the graph querying language UnQL. The main idea of UnQL is that graph queries are fully captured by structural recursion that is suitable for efficient composition. We show that the idea can be applied to graph-based model transformations. We have implemented a prototype of the framework and tested it with several nontrivial examples. Our new framework supports systematic development of model transformation "in the large" with the advantage that it can automatically remove inefficiencies arising from their composition.
We have proposed a model of periodic axial magnetized hollow tube for atom guidance (1999 Opt. Co... more We have proposed a model of periodic axial magnetized hollow tube for atom guidance (1999 Opt. Commun. 160 72-4). In the present paper, an analytic solution of the magnetic field inside the tube is obtained and the transport efficiency of the cold atoms in the magnetic tube at different tube intensities of magnetization is discussed. The effect of the curvature of magnetic tube on the atom transport efficiency is also considered. We have found that the tube has a cooling effect on the transverse temperature of the transported atoms.
Proceedings of the 29th Annual Acm Symposium, Mar 24, 2014
ABSTRACT The All Nearest Smaller Values (ANSV) problem is an important problem for parallel progr... more ABSTRACT The All Nearest Smaller Values (ANSV) problem is an important problem for parallel programming as it can be used to solve several problems and is one of the phases of several other parallel algorithms. We formally develop by construction a functional parallel program for solving the ANSV problem using the theory of Bulk Synchronous Parallel (BSP) homomorphisms within the Coq proof assistant. The performances of the Bulk Synchronous Parallel ML program obtained from Coq is compared to a version derived without software support (pen-and-paper) and implemented using the Orléans Skeleton Library of algorithmic skeletons, and to a (unproved correct) direct implementation of the BSP algorithm of He and Huang.
A programmable structured document is a structured document with dynamically calculated component... more A programmable structured document is a structured document with dynamically calculated components that can be specified by users in a functional programming language. TreeCalc, a tree version of spreadsheet, is an experimental system demonstrating the notion, basing on the XML viewer and editor, Fungus, developed by Justsystem. TreeCalc takes an XML document representing, for example, a math expression and displays the expression together with the computed result, or a document with tagged chapter and section titles and computes the table of contents of the document. The result of the expression or the table of contents is automatically updated when the user edits the document.
We report a new mixed methyl-fluoroalkyl (Rf) 3,5-substituted pyrazole, PzRf,CH3, with Rf=C2F5. A... more We report a new mixed methyl-fluoroalkyl (Rf) 3,5-substituted pyrazole, PzRf,CH3, with Rf=C2F5. An X-ray structural comparison of PzRf,CH3 (Rf=CF3 and C2F5) reveals a similar boat-type H-bonded tetrameric architecture, dominated by the 3,5 tautomers. The tetramers compactness could be compared by computing the volume of the tetrahedron defined by the geometric centers of the four pyrazole rings. Using this criterion the C2F5 group is found to induce a tighter intratetrameric packing relative to CF3, in addition to exhibiting a possibly higher degree of N–H proton delocalization.The new TpRf,CH3 (Rf=C2F5) sodium scorpionate is also reported. The X-ray structure of NaTpC2F5,CH3(H2O) shows discrete mononuclear units. The Na-coordinated H2O exhibits weak, 2.6Å intermolecular Na–O–H···F contacts leading to the formation of a head-to-tail chain assembly. In contrast, the NaTpCF3,CH3 (H2O) complex forms dimers in solid-state, supported by Na-bridging water ligands and intermolecular Na···F interactions.The presence of metal-bonded H2O in the sodium complex of TpC2F5,CH3 as well as the formation of discrete complexes when CF3 is replaced by C2F5 in TpRf,CH3 reflect both the strong σ electronic acceptor nature of the ligand and its enhanced steric bulkiness.
This paper introduces accumulation into list homomorphisms for systematic development of both eff... more This paper introduces accumulation into list homomorphisms for systematic development of both efficient and correct parallel programs. New parallelizable recursive pattern called H-homomorphism is given, and transformations from sequential patterns in the H-form and H ′form into (H-)homomorphism are shown. We illustrate the power of our formalization by developing a novel and general parallel program for a class of interesting and challenging problems, known as maximum marking problems.
Proceedings of the 15th Symposium on Principles and Practice of Declarative Programming - PPDP '13, 2013
ABSTRACT We introduce a lambda calculus λTFG for transformations of finite graphs by generalizing... more ABSTRACT We introduce a lambda calculus λTFG for transformations of finite graphs by generalizing and extending an existing calculus UnCAL. Whereas UnCAL can treat only unordered graphs, λTFG can treat a variety of graph models: directed edge-labeled graphs whose branch styles are represented by monads T. For example, λTFG can treat unordered graphs, ordered graphs, weighted graphs, probability graphs, and so on, by using the powerset monad, list monad, multiset monad, probability monad, respectively. In λTFG, graphs are considered as extension of tree data structures, i.e. as infinite (regular) trees, so the semantics is given with bisimilarity. A remarkable feature of UnCAL and λTFG is structural recursion for graphs, which gives a systematic programming basis like that for trees. Despite the non-well-foundedness of graphs, by suitably restricting the structural recursion, UnCAL and λTFG ensures that there is a termination property and that all transformations preserve the finiteness of the graphs. The structural recursion is defined in a "divide-and-aggregate" way; "aggregation" is done by connecting graphs with ε-edges, which are similar to the ε-transitions of automata. We give a suitable general definition of bisimilarity, taking account of ε-edges; then we show that the structural recursion is well defined with respect to the bisimilarity.
Proceedings of the 2009 ACM symposium on Applied Computing - SAC '09, 2009
Model transformation plays an important role in model-driven software development that aims to in... more Model transformation plays an important role in model-driven software development that aims to introduce significant efficiencies and rigor to the theory and practice of software development. Although models may have different notations and representations, they are basically graphs, and model transformations are thus nothing but graph transformations. Despite a large amount of theoretical work and a lot of experience with research prototypes on graph-based model transformations, it remains an open issue how to compose model transformations. In this paper, we report our first attempt at a compositional framework for graph-based model transformations using the graph querying language UnQL. The main idea of UnQL is that graph queries are fully captured by structural recursion that is suitable for efficient composition. We show that the idea can be applied to graph-based model transformations. We have implemented a prototype of the framework and tested it with several nontrivial examples. Our new framework supports systematic development of model transformation "in the large" with the advantage that it can automatically remove inefficiencies arising from their composition.
Proceedings of the 13th international ACM SIGPLAN symposium on Principles and practices of declarative programming - PPDP '11, 2011
This paper presents a new approach to solving the problem of verification of graph transformation... more This paper presents a new approach to solving the problem of verification of graph transformation, by proposing a new static verification algorithm for the Core UnCAL, the query algebra for graph-structured databases proposed by Bunemann et al. Given a graph transformation annotated with schema information, our algorithm statically verifies that any graph satisfying the input schema is converted by the transformation to a graph satisfying the output schema. We tackle the problem by first reformulating the semantics of UnCAL into monadic second-order logic (MSO). The logicbased foundation allows to express the schema satisfaction of transformations as the validity of MSO formulas over graph structures. Then by exploiting the two established properties of UnCAL called bisimulation-genericity and compactness, we reduce the problem to the validity of MSO over trees, which has a sound and complete decision procedure. The algorithm has been efficiently implemented; all the graph transformations in this paper and the system web page can be verified within several seconds.
ATL is a language for describing model transformations currently in uni-direction. In our previou... more ATL is a language for describing model transformations currently in uni-direction. In our previous work we have shown that transformations of graph structures given in some form can be bidirectionalized and have implemented a system called GRoundTram system for bidirectional graph transformations. We say a transformation t is bidirectionalized when we obtain a backward transformation t′ so that the pair (t,t′) of transformations satisfies certain well-behavedness properties. Bidirectional model transformation is used to reflect the changes in the target model back to the source model, and vice versa. In this paper, as a first step toward realizing practical bidirectional model transformations, we present bidirectionalization of core part of the ATL by encoding it in the UnQL language, which is used as a transformation language in the GRoundTram system. We give the algorithm for the encoding, based on which we have implemented the system for bidirectionalizing the core ATL in OCaml language.
2011 26th IEEE/ACM International Conference on Automated Software Engineering (ASE 2011), 2011
Bidirectional model transformation is useful for maintaining consistency between two models, and ... more Bidirectional model transformation is useful for maintaining consistency between two models, and has many potential applications in software development including model synchronization, round-trip engineering, and software evolution. Despite these attractive uses, the lack of a practical tool support for systematic development of well-behaved and efficient bidirectional model transformation prevents it from being widely used. In this paper, we solve this problem by proposing an integrated framework called GRoundTram, which is carefully designed and implemented for compositional development of well-behaved and efficient bidirectional model transformations. GRoundTram is built upon a well-founded bidirectional framework, and is equipped with a user-friendly language for coding bidirectional model transformation, a new tool for validating both models and bidirectional model transformations, an optimization mechanism for improving efficiency, and a powerful debugging environment for testing bidirectional behavior. GRoundTram has been used by people of other groups and their results show its usefulness in practice.
The measurement resolution of an atomic force microscope (AFM) is largely dependent on the radius... more The measurement resolution of an atomic force microscope (AFM) is largely dependent on the radius of the tip. Meanwhile, when using AFM to study nanoscale surface properties, the value of the tip radius is needed in calculations. As such, estimation of the tip radius is important for analyzing results taken using an AFM. In this study, a geometrical model created by scanning a step structure with an AFM tip was developed. The tip was assumed to have a hemispherical cone shape. Profiles simulated by tips with different scanning radii were calculated by fast Fourier transform (FFT). By analyzing the influence of tip radius variation on the spectra of simulated profiles, it was found that low-frequency harmonics were more susceptible, and that the relationship between the tip radius and the low-frequency harmonic amplitude of the step structure varied monotonically. Based on this regularity, we developed a new method to characterize the radius of the hemispherical tip. The tip radii estimated with this approach were comparable to the results obtained using scanning electron microscope imaging and blind reconstruction methods.
Proceedings of the eighteenth annual ACM symposium on Parallelism in algorithms and architectures - SPAA '06, 2006
Tree contraction algorithms, whose idea was first proposed by Miller and Reif, are important para... more Tree contraction algorithms, whose idea was first proposed by Miller and Reif, are important parallel algorithms to implement efficient parallel programs manipulating trees. Despite their efficiency, the tree contraction algorithms have not been widely used due to the difficulties in deriving the tree contracting operations. In particular, the derivation of the tree contracting operations is much difficult when multiple values are referred and updated in each step of the contractions. Such computations often appear in dynamic programming problems on trees.
International Journal of Parallel Programming, 2007
Computations on two-dimensional arrays such as matrix computations are one of the most fundamenta... more Computations on two-dimensional arrays such as matrix computations are one of the most fundamental and ubiquitous in computational science and its vast application areas, but development of efficient parallel programs on two-dimensional arrays is known to be hard. In this paper, we propose a compositional framework which supports users, even with little knowledge about parallel machines, to systematically develop both correct and efficient parallel programs on two-dimensional arrays. The key feature of our framework is a novel use of the abide-tree representation of two-dimensional arrays, which not only inherits the advantages of tree representations of matrix where recursive blocked algorithms can be defined to achieve better performance, but also supports transformational development of parallel programs and architecture independent implementation owing to its solid theoretical foundation -the theory of constructive algorithmics.
Trees are useful data structures, but to design efficient parallel programs over trees is known t... more Trees are useful data structures, but to design efficient parallel programs over trees is known to be more difficult than to do over lists. Although several important tree skeletons have been proposed to simplify parallel programming on trees, few studies have been reported on how to systematically use them in solving practical problems; it is neither clear how to make a good combination of skeletons to solve a given problem, nor obvious how to find suitable operators used in a single skeleton. In this paper, we report our first attempt to resolve these problems, proposing two important transformations, the tree diffusion transformation and the tree context preservation transformation. The tree diffusion transformation allows one to use familiar recursive definitions to develop his parallel programs, while the tree context preservation transformation shows how to derive associative operators that are required when using tree skeletons. We illustrate our approach by deriving an efficient parallel program for solving a nontrivial problem called the party planning problem, the tree version of the famous maximum-weight-sum problem.
ABSTRACT We present a new derivation of efficient algorithms for a class of optimization problems... more ABSTRACT We present a new derivation of efficient algorithms for a class of optimization problems called maximum marking problems. We extend the class of weight functions used in the specification to allow for weight functions with accumulation, which is particularly useful when the weight of each element depends on adjacent elements. This extension of weight functions enables us to treat more interesting optimization problems such as a variant of the maximum segment sum problem and the fair bonus distribution problem. The complexity of the derived algorithm is linear with respect to the size of the input data.
Proceedings of the 2009 Acm Symposium on Applied Computing, 2009
Model transformation plays an important role in model-driven software development that aims to in... more Model transformation plays an important role in model-driven software development that aims to introduce significant efficiencies and rigor to the theory and practice of software development. Although models may have different notations and representations, they are basically graphs, and model transformations are thus nothing but graph transformations. Despite a large amount of theoretical work and a lot of experience with research prototypes on graph-based model transformations, it remains an open issue how to compose model transformations. In this paper, we report our first attempt at a compositional framework for graph-based model transformations using the graph querying language UnQL. The main idea of UnQL is that graph queries are fully captured by structural recursion that is suitable for efficient composition. We show that the idea can be applied to graph-based model transformations. We have implemented a prototype of the framework and tested it with several nontrivial examples. Our new framework supports systematic development of model transformation "in the large" with the advantage that it can automatically remove inefficiencies arising from their composition.
We have proposed a model of periodic axial magnetized hollow tube for atom guidance (1999 Opt. Co... more We have proposed a model of periodic axial magnetized hollow tube for atom guidance (1999 Opt. Commun. 160 72-4). In the present paper, an analytic solution of the magnetic field inside the tube is obtained and the transport efficiency of the cold atoms in the magnetic tube at different tube intensities of magnetization is discussed. The effect of the curvature of magnetic tube on the atom transport efficiency is also considered. We have found that the tube has a cooling effect on the transverse temperature of the transported atoms.
Proceedings of the 29th Annual Acm Symposium, Mar 24, 2014
ABSTRACT The All Nearest Smaller Values (ANSV) problem is an important problem for parallel progr... more ABSTRACT The All Nearest Smaller Values (ANSV) problem is an important problem for parallel programming as it can be used to solve several problems and is one of the phases of several other parallel algorithms. We formally develop by construction a functional parallel program for solving the ANSV problem using the theory of Bulk Synchronous Parallel (BSP) homomorphisms within the Coq proof assistant. The performances of the Bulk Synchronous Parallel ML program obtained from Coq is compared to a version derived without software support (pen-and-paper) and implemented using the Orléans Skeleton Library of algorithmic skeletons, and to a (unproved correct) direct implementation of the BSP algorithm of He and Huang.
A programmable structured document is a structured document with dynamically calculated component... more A programmable structured document is a structured document with dynamically calculated components that can be specified by users in a functional programming language. TreeCalc, a tree version of spreadsheet, is an experimental system demonstrating the notion, basing on the XML viewer and editor, Fungus, developed by Justsystem. TreeCalc takes an XML document representing, for example, a math expression and displays the expression together with the computed result, or a document with tagged chapter and section titles and computes the table of contents of the document. The result of the expression or the table of contents is automatically updated when the user edits the document.
We report a new mixed methyl-fluoroalkyl (Rf) 3,5-substituted pyrazole, PzRf,CH3, with Rf=C2F5. A... more We report a new mixed methyl-fluoroalkyl (Rf) 3,5-substituted pyrazole, PzRf,CH3, with Rf=C2F5. An X-ray structural comparison of PzRf,CH3 (Rf=CF3 and C2F5) reveals a similar boat-type H-bonded tetrameric architecture, dominated by the 3,5 tautomers. The tetramers compactness could be compared by computing the volume of the tetrahedron defined by the geometric centers of the four pyrazole rings. Using this criterion the C2F5 group is found to induce a tighter intratetrameric packing relative to CF3, in addition to exhibiting a possibly higher degree of N–H proton delocalization.The new TpRf,CH3 (Rf=C2F5) sodium scorpionate is also reported. The X-ray structure of NaTpC2F5,CH3(H2O) shows discrete mononuclear units. The Na-coordinated H2O exhibits weak, 2.6Å intermolecular Na–O–H···F contacts leading to the formation of a head-to-tail chain assembly. In contrast, the NaTpCF3,CH3 (H2O) complex forms dimers in solid-state, supported by Na-bridging water ligands and intermolecular Na···F interactions.The presence of metal-bonded H2O in the sodium complex of TpC2F5,CH3 as well as the formation of discrete complexes when CF3 is replaced by C2F5 in TpRf,CH3 reflect both the strong σ electronic acceptor nature of the ligand and its enhanced steric bulkiness.
This paper introduces accumulation into list homomorphisms for systematic development of both eff... more This paper introduces accumulation into list homomorphisms for systematic development of both efficient and correct parallel programs. New parallelizable recursive pattern called H-homomorphism is given, and transformations from sequential patterns in the H-form and H ′form into (H-)homomorphism are shown. We illustrate the power of our formalization by developing a novel and general parallel program for a class of interesting and challenging problems, known as maximum marking problems.
Proceedings of the 15th Symposium on Principles and Practice of Declarative Programming - PPDP '13, 2013
ABSTRACT We introduce a lambda calculus λTFG for transformations of finite graphs by generalizing... more ABSTRACT We introduce a lambda calculus λTFG for transformations of finite graphs by generalizing and extending an existing calculus UnCAL. Whereas UnCAL can treat only unordered graphs, λTFG can treat a variety of graph models: directed edge-labeled graphs whose branch styles are represented by monads T. For example, λTFG can treat unordered graphs, ordered graphs, weighted graphs, probability graphs, and so on, by using the powerset monad, list monad, multiset monad, probability monad, respectively. In λTFG, graphs are considered as extension of tree data structures, i.e. as infinite (regular) trees, so the semantics is given with bisimilarity. A remarkable feature of UnCAL and λTFG is structural recursion for graphs, which gives a systematic programming basis like that for trees. Despite the non-well-foundedness of graphs, by suitably restricting the structural recursion, UnCAL and λTFG ensures that there is a termination property and that all transformations preserve the finiteness of the graphs. The structural recursion is defined in a "divide-and-aggregate" way; "aggregation" is done by connecting graphs with ε-edges, which are similar to the ε-transitions of automata. We give a suitable general definition of bisimilarity, taking account of ε-edges; then we show that the structural recursion is well defined with respect to the bisimilarity.
Proceedings of the 2009 ACM symposium on Applied Computing - SAC '09, 2009
Model transformation plays an important role in model-driven software development that aims to in... more Model transformation plays an important role in model-driven software development that aims to introduce significant efficiencies and rigor to the theory and practice of software development. Although models may have different notations and representations, they are basically graphs, and model transformations are thus nothing but graph transformations. Despite a large amount of theoretical work and a lot of experience with research prototypes on graph-based model transformations, it remains an open issue how to compose model transformations. In this paper, we report our first attempt at a compositional framework for graph-based model transformations using the graph querying language UnQL. The main idea of UnQL is that graph queries are fully captured by structural recursion that is suitable for efficient composition. We show that the idea can be applied to graph-based model transformations. We have implemented a prototype of the framework and tested it with several nontrivial examples. Our new framework supports systematic development of model transformation "in the large" with the advantage that it can automatically remove inefficiencies arising from their composition.
Proceedings of the 13th international ACM SIGPLAN symposium on Principles and practices of declarative programming - PPDP '11, 2011
This paper presents a new approach to solving the problem of verification of graph transformation... more This paper presents a new approach to solving the problem of verification of graph transformation, by proposing a new static verification algorithm for the Core UnCAL, the query algebra for graph-structured databases proposed by Bunemann et al. Given a graph transformation annotated with schema information, our algorithm statically verifies that any graph satisfying the input schema is converted by the transformation to a graph satisfying the output schema. We tackle the problem by first reformulating the semantics of UnCAL into monadic second-order logic (MSO). The logicbased foundation allows to express the schema satisfaction of transformations as the validity of MSO formulas over graph structures. Then by exploiting the two established properties of UnCAL called bisimulation-genericity and compactness, we reduce the problem to the validity of MSO over trees, which has a sound and complete decision procedure. The algorithm has been efficiently implemented; all the graph transformations in this paper and the system web page can be verified within several seconds.
ATL is a language for describing model transformations currently in uni-direction. In our previou... more ATL is a language for describing model transformations currently in uni-direction. In our previous work we have shown that transformations of graph structures given in some form can be bidirectionalized and have implemented a system called GRoundTram system for bidirectional graph transformations. We say a transformation t is bidirectionalized when we obtain a backward transformation t′ so that the pair (t,t′) of transformations satisfies certain well-behavedness properties. Bidirectional model transformation is used to reflect the changes in the target model back to the source model, and vice versa. In this paper, as a first step toward realizing practical bidirectional model transformations, we present bidirectionalization of core part of the ATL by encoding it in the UnQL language, which is used as a transformation language in the GRoundTram system. We give the algorithm for the encoding, based on which we have implemented the system for bidirectionalizing the core ATL in OCaml language.
2011 26th IEEE/ACM International Conference on Automated Software Engineering (ASE 2011), 2011
Bidirectional model transformation is useful for maintaining consistency between two models, and ... more Bidirectional model transformation is useful for maintaining consistency between two models, and has many potential applications in software development including model synchronization, round-trip engineering, and software evolution. Despite these attractive uses, the lack of a practical tool support for systematic development of well-behaved and efficient bidirectional model transformation prevents it from being widely used. In this paper, we solve this problem by proposing an integrated framework called GRoundTram, which is carefully designed and implemented for compositional development of well-behaved and efficient bidirectional model transformations. GRoundTram is built upon a well-founded bidirectional framework, and is equipped with a user-friendly language for coding bidirectional model transformation, a new tool for validating both models and bidirectional model transformations, an optimization mechanism for improving efficiency, and a powerful debugging environment for testing bidirectional behavior. GRoundTram has been used by people of other groups and their results show its usefulness in practice.
The measurement resolution of an atomic force microscope (AFM) is largely dependent on the radius... more The measurement resolution of an atomic force microscope (AFM) is largely dependent on the radius of the tip. Meanwhile, when using AFM to study nanoscale surface properties, the value of the tip radius is needed in calculations. As such, estimation of the tip radius is important for analyzing results taken using an AFM. In this study, a geometrical model created by scanning a step structure with an AFM tip was developed. The tip was assumed to have a hemispherical cone shape. Profiles simulated by tips with different scanning radii were calculated by fast Fourier transform (FFT). By analyzing the influence of tip radius variation on the spectra of simulated profiles, it was found that low-frequency harmonics were more susceptible, and that the relationship between the tip radius and the low-frequency harmonic amplitude of the step structure varied monotonically. Based on this regularity, we developed a new method to characterize the radius of the hemispherical tip. The tip radii estimated with this approach were comparable to the results obtained using scanning electron microscope imaging and blind reconstruction methods.
Uploads
Papers by Zhenjiang Hu