Pub Date : 2006-03-06DOI: 10.1163/157404006779194088
P. Karamanis, D. Bégué, C. Pouchan
We studied the structure and polarizability of small stoichiometric gallium arsenide clusters (GaAs)n (n= 2, 3, 4, 5, 6 and 8) with conventional ab-initio and density functional methods relying on correlation consistent large-core relativistic pseudo potential basis set. Our results show that computations based on those basis sets yield reasonable results compared to all electron basis sets and the polarizability/atom of small gallium arsenide clusters up to the octamer, is predicted to be larger than the Clausius-Mosotti bulk value.
{"title":"Structure and Polarizability of Small (GaAs)n Clusters (n= 2, 3, 4, 5, 6, and 8)","authors":"P. Karamanis, D. Bégué, C. Pouchan","doi":"10.1163/157404006779194088","DOIUrl":"https://doi.org/10.1163/157404006779194088","url":null,"abstract":"We studied the structure and polarizability of small stoichiometric gallium arsenide clusters (GaAs)n (n= 2, 3, 4, 5, 6 and 8) with conventional ab-initio and density functional methods relying on correlation consistent large-core relativistic pseudo potential basis set. Our results show that computations based on those basis sets yield reasonable results compared to all electron basis sets and the polarizability/atom of small gallium arsenide clusters up to the octamer, is predicted to be larger than the Clausius-Mosotti bulk value.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83145373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1163/157404006777491945
E. Stone, A. Askari, H. Tat
During chatter in metal cutting the tool vibration would cause a variation in "effective" rake angle of the cutter, generating a force variation that depends on penetration rate: a kind of process damping. This effect is examined for forces computed both from a theoretical Merchant-type model, and from a numerical database of forces for metal cutting constructed from a suite of AdvantEdge simulations. Since the tool can potential vibrate at any angle relative to the workpiece, the forces for varying angle of vibration were computed, and the dynamic stability consequences considered. It is found that the two models lead to similar forces for varying vibration angle, at least through first order. Depending on the vibration angle the force will either increase or decrease with both chip load and penetration rate, reflecting the difference in the effect on the chipload and cutting speed with varying vibration direction. Second order terms in penetration rate were different in the two formulations, possibly a result of approximations used in the calculations involved in the Merchant formulation. Dynamically this means that the linear stability of each vibration angle is the similar for the two models, while the differences in nonlinear terms results in differences in the type Hopf bifurcation observed upon loss of stability.
{"title":"Investigations of Nonlinear Forces in Metal Cutting","authors":"E. Stone, A. Askari, H. Tat","doi":"10.1163/157404006777491945","DOIUrl":"https://doi.org/10.1163/157404006777491945","url":null,"abstract":"During chatter in metal cutting the tool vibration would cause a variation in \"effective\" rake angle of the cutter, generating a force variation that depends on penetration rate: a kind of process damping. This effect is examined for forces computed both from a theoretical Merchant-type model, and from a numerical database of forces for metal cutting constructed from a suite of AdvantEdge simulations. Since the tool can potential vibrate at any angle relative to the workpiece, the forces for varying angle of vibration were computed, and the dynamic stability consequences considered. It is found that the two models lead to similar forces for varying vibration angle, at least through first order. Depending on the vibration angle the force will either increase or decrease with both chip load and penetration rate, reflecting the difference in the effect on the chipload and cutting speed with varying vibration direction. Second order terms in penetration rate were different in the two formulations, possibly a result of approximations used in the calculations involved in the Merchant formulation. Dynamically this means that the linear stability of each vibration angle is the similar for the two models, while the differences in nonlinear terms results in differences in the type Hopf bifurcation observed upon loss of stability.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82503741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1163/157404006779194114
N. Dugan, S. Erkoç
General information about the problem of determining ground-state geometries of atomic clusters has been given. Modified diffusion Monte Carlo (MDMC) method which was recently developed for this problem has been reviewed. A technique, called the rotation operation, has been proposed to escape from local minima. Information about empirical potential energy functions, used in the computations, has been given. Binding energy results for ZnnCdm and (AlTiNi)n clusters obtained by the combination of the MDMC method and the rotation operation have been presented and these results have been compared with the molecular dynamics (MD) results. Efficiency of the method has been investigated by comparing the results and the computation times with the results of the single walker MDMC method - rotation operation combination.
{"title":"Geometry Optimization of ZnnCdm and (AlTiNi)n Clusters by the Modified Diffusion Monte Carlo Method","authors":"N. Dugan, S. Erkoç","doi":"10.1163/157404006779194114","DOIUrl":"https://doi.org/10.1163/157404006779194114","url":null,"abstract":"General information about the problem of determining ground-state geometries of atomic clusters has been given. Modified diffusion Monte Carlo (MDMC) method which was recently developed for this problem has been reviewed. A technique, called the rotation operation, has been proposed to escape from local minima. Information about empirical potential energy functions, used in the computations, has been given. Binding energy results for ZnnCdm and (AlTiNi)n clusters obtained by the combination of the MDMC method and the rotation operation have been presented and these results have been compared with the molecular dynamics (MD) results. Efficiency of the method has been investigated by comparing the results and the computation times with the results of the single walker MDMC method - rotation operation combination.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80415036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1163/157404006778330861
M. Breuß
We discuss some important issues arising when approximating numerically stabilised inverse diffusion processes. We prove rigorously the necessity of a minmod-type stabilisation. Furthermore, we give rigorously verified assertions concerning the occurence of undesirable staircasing aka terracing artefacts. The theoretical results are supplemented by numerical tests.
{"title":"An analysis of discretisations of inverse diffusion equations","authors":"M. Breuß","doi":"10.1163/157404006778330861","DOIUrl":"https://doi.org/10.1163/157404006778330861","url":null,"abstract":"We discuss some important issues arising when approximating numerically stabilised inverse diffusion processes. We prove rigorously the necessity of a minmod-type stabilisation. Furthermore, we give rigorously verified assertions concerning the occurence of undesirable staircasing aka terracing artefacts. The theoretical results are supplemented by numerical tests.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90145559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1163/157404006779194178
W. Hug
Traditional methods for characterizing molecular vibrations were developed for small molecules and are not well suited for understanding nuclear motions of large molecules and of clusters. We present a procedure based on representing normal modes, including translations and rotations, as vectors in 3N dimensional space, where N is the number of nuclei. Double-contracting dyads formed from them allows for a quantitative definition of the overlap and the similarity of nuclear motions of whole molecules, of clusters of molecules, and of arbitrary fragments.
{"title":"Understanding Normal Modes of Molecules and Clusters","authors":"W. Hug","doi":"10.1163/157404006779194178","DOIUrl":"https://doi.org/10.1163/157404006779194178","url":null,"abstract":"Traditional methods for characterizing molecular vibrations were developed for small molecules and are not well suited for understanding nuclear motions of large molecules and of clusters. We present a procedure based on representing normal modes, including translations and rotations, as vectors in 3N dimensional space, where N is the number of nuclei. Double-contracting dyads formed from them allows for a quantitative definition of the overlap and the similarity of nuclear motions of whole molecules, of clusters of molecules, and of arbitrary fragments.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75500602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1163/157404006779194150
J. Henriksson, Susanna Nyrell, P. Norman
The spin characteristics of octahedrically coordinated Fe(II) compounds are determined from first-principles quantum chemical calculations. Four novel Fe(II) spin transition materials are suggested ...
{"title":"Theoretical Design of Optical Switches Using the Spin Transition Phenomenon","authors":"J. Henriksson, Susanna Nyrell, P. Norman","doi":"10.1163/157404006779194150","DOIUrl":"https://doi.org/10.1163/157404006779194150","url":null,"abstract":"The spin characteristics of octahedrically coordinated Fe(II) compounds are determined from first-principles quantum chemical calculations. Four novel Fe(II) spin transition materials are suggested ...","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82969138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1163/157404006779194169
Sunwoo Kang, Shihai Yan, J. Lee
Supramolecular chemistry now has become a central part of the research activities. Basically, it mostly concerns molecular recognition and self aggregation by non-covalent weak intermolecular interactions, such as hydrogen bonding, π-π stacking, and van der Waals interactions. The computational applications on such large systems are limited for their structural complexity. Several examples of the computational approaches to understand molecular recognition and self-aggregation are discussed. Firstly, bifunctional (fluorescence and visible light absorption) anion sensing mechanism is supported by the DFT calculations. Secondly, an experimentally observed selective recognition of Cu2+ by an azobenzene-appended receptor, which can exhibit Cu2+ selectivity by color change, is discussed based on computational approach. Finally, the intermolecular interaction, which is useful for predicting the self-assembled structures, can be understood by replicating the monomer unit and manipulating the translation and rotation.
{"title":"Invited Paper: Theoretical Studies on Molecular Recognition and Self-Assembly","authors":"Sunwoo Kang, Shihai Yan, J. Lee","doi":"10.1163/157404006779194169","DOIUrl":"https://doi.org/10.1163/157404006779194169","url":null,"abstract":"Supramolecular chemistry now has become a central part of the research activities. Basically, it mostly concerns molecular recognition and self aggregation by non-covalent weak intermolecular interactions, such as hydrogen bonding, π-π stacking, and van der Waals interactions. The computational applications on such large systems are limited for their structural complexity. Several examples of the computational approaches to understand molecular recognition and self-aggregation are discussed. Firstly, bifunctional (fluorescence and visible light absorption) anion sensing mechanism is supported by the DFT calculations. Secondly, an experimentally observed selective recognition of Cu2+ by an azobenzene-appended receptor, which can exhibit Cu2+ selectivity by color change, is discussed based on computational approach. Finally, the intermolecular interaction, which is useful for predicting the self-assembled structures, can be understood by replicating the monomer unit and manipulating the translation and rotation.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76033101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1163/157404006779194141
M. Boczar, Łukasz Boda, M. Wójcik
Theoretical model for vibrational interactions in the hydrogen bonds in molecular crystals with four molecules forming two centrosymmetric dimers in the unit cell is presented. The model takes into account anharmonic-type couplings between the high-frequency N-H(D) and the low-frequency N…O stretching vibrations in each hydrogen bond, resonance interactions (Davydov coupling) between equivalent hydrogen bonds in each dimer, resonance interdimer interactions within an unit cell and Fermi resonance between the N-H(D) stretching fundamental and the first overtone of the N-H(D) in-plane bending vibrations. The vibrational Hamiltonian, selection rules, and expressions for the integral properties of an absorption spectrum are derived. The model is used for theoretical simulation of the νs stretching bands of 1-methylthymine and its ND derivative at 300 K. The effect of deuteration is successfully reproduced by our model.
提出了四分子在单晶中形成两个中心对称二聚体的分子晶体中氢键振动相互作用的理论模型。该模型考虑了每个氢键中高频N- h (D)和低频N…O拉伸振动之间的非谐型耦合，每个二聚体中等效氢键之间的共振相互作用(Davydov耦合)，单元胞内共振二聚体之间的相互作用以及N- h (D)拉伸基频和N- h (D)平面弯曲振动的第一泛音之间的费米共振。导出了振动哈密顿量、选择规则和吸收光谱积分性质的表达式。利用该模型对1-甲基胸腺嘧啶及其ND衍生物在300 K下的νs拉伸带进行了理论模拟。我们的模型成功地再现了氘化的效应。
{"title":"Theoretical Modeling of the N-H and N-D Stretching Bands of Hydrogen-Bonded 1-Methylthymine Crystal and Its Deuterated Form","authors":"M. Boczar, Łukasz Boda, M. Wójcik","doi":"10.1163/157404006779194141","DOIUrl":"https://doi.org/10.1163/157404006779194141","url":null,"abstract":"Theoretical model for vibrational interactions in the hydrogen bonds in molecular crystals with four molecules forming two centrosymmetric dimers in the unit cell is presented. The model takes into account anharmonic-type couplings between the high-frequency N-H(D) and the low-frequency N…O stretching vibrations in each hydrogen bond, resonance interactions (Davydov coupling) between equivalent hydrogen bonds in each dimer, resonance interdimer interactions within an unit cell and Fermi resonance between the N-H(D) stretching fundamental and the first overtone of the N-H(D) in-plane bending vibrations. The vibrational Hamiltonian, selection rules, and expressions for the integral properties of an absorption spectrum are derived. The model is used for theoretical simulation of the νs stretching bands of 1-methylthymine and its ND derivative at 300 K. The effect of deuteration is successfully reproduced by our model.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78993620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1163/157404006777491954
E. Francomano, C. Lodato, S. Lopes, A. Tortorici
A fundamental problem in the processing of image sequences is the computation of the velocity field of the apparent motion of brightness patterns usually referred to optical flow. In this paper a novel optical flow estimator based on a bivariate quasi-interpolant operator is presented. Namely, a non linear minimizing technique has been employed to compute the velocity vectors by modeling the flow field with a 2D quasi-interpolant operator based on centered cardinal B-spline functions. In this way an efficient computational scheme for optical flow estimate is provided. In addition the large solving linear systems involved in the process are sparse. Experiments on several image sequences have been carried out in order to investigate the performance of the optical flow estimator.
{"title":"An algorithm for optical flow computation based on a quasi-interpolant operator","authors":"E. Francomano, C. Lodato, S. Lopes, A. Tortorici","doi":"10.1163/157404006777491954","DOIUrl":"https://doi.org/10.1163/157404006777491954","url":null,"abstract":"A fundamental problem in the processing of image sequences is the computation of the velocity field of the apparent motion of brightness patterns usually referred to optical flow. In this paper a novel optical flow estimator based on a bivariate quasi-interpolant operator is presented. Namely, a non linear minimizing technique has been employed to compute the velocity vectors by modeling the flow field with a 2D quasi-interpolant operator based on centered cardinal B-spline functions. In this way an efficient computational scheme for optical flow estimate is provided. In addition the large solving linear systems involved in the process are sparse. Experiments on several image sequences have been carried out in order to investigate the performance of the optical flow estimator.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72734936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1163/157404006779194123
S. Bagui
In this paper, we provide detailed mapping rules (a methodology) to convert an ER schema into an object relationship (OR) schema. The mapping rules are presented in a manner that will keep as much of the semantics of the database intact, in order to smoothen the important step of data migration from an ER schema to an OR schema. This OR schema should also serve as a conceptual design tool for object-oriented data models, very much like the ER diagrams are a conceptual design tool for relational databases. Since we are mainly discussing the conversion from an ER model to an OR model, we are limiting the discussion in this paper to the structural aspects of the OR model.
{"title":"Rules for Migrating from Entity Relationship (ER) Diagrams to Object Relationship (OR) Diagrams","authors":"S. Bagui","doi":"10.1163/157404006779194123","DOIUrl":"https://doi.org/10.1163/157404006779194123","url":null,"abstract":"In this paper, we provide detailed mapping rules (a methodology) to convert an ER schema into an object relationship (OR) schema. The mapping rules are presented in a manner that will keep as much of the semantics of the database intact, in order to smoothen the important step of data migration from an ER schema to an OR schema. This OR schema should also serve as a conceptual design tool for object-oriented data models, very much like the ER diagrams are a conceptual design tool for relational databases. Since we are mainly discussing the conversion from an ER model to an OR model, we are limiting the discussion in this paper to the structural aspects of the OR model.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75982026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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