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  • 1
    ISSN: 1434-601X
    Schlagwort(e): 21.10.Tg ; 21.60.−n ; 25.20.Lj ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The115In(γ, γ′) reaction was measured at the S-DALINAC using bremsstrahlung with endpoint energiesE 0=3.1, 4.6 and 5.2 MeV. In the excitation energy range of 1–5 MeV in total 32 transitions were observed, 18 of which were hithertoo unknown. The results are compared to two quasiparticle-phonon model calculations, one with a model space of ‘quasiparticle⊗phonon’ and one extended by ‘quasiparticle⊗two-phonon’ configurations. A substantial improvement is achieved in the description of low-lying115In states by the consideration of the more complex configurations. The calculations quantitatively account for the summed115In(γ, γ′) integrated cross sections and show a comparable amount of fragmentation of the individual transition strengths. The model interpretation of the microscopic structure of the experimentally observed transitions is discussed.
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  • 2
    ISSN: 1434-601X
    Schlagwort(e): 27.60.+j ; 25.70.Gh
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The level scheme of147Tb has been extended to 116 levels and 198 transitions in two experiments with the OSIRIS Compton suppressed detector array at the HMI Berlin with the reactions122Sn(31P, 6n)147Tb at 160 MeV and120Sn(31P, 4n)147Tb at 152 MeV. Evidence for a new high spin isomer atE=7664.1 keV with a life-time of the order of 2 ns has been found.
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  • 3
    ISSN: 1434-601X
    Schlagwort(e): 23.20.Lv ; 23.20.En ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract High spin states are populated in102Ag using the reaction16O+89Y with projectile energies in the energy range 60–80 MeV. Gamma multipolarities are inferred from DCO ratios and coincidence relationships are established among the gamma rays assigned to102Ag. A comprehensive level scheme is constructed with four band systems, two of positive parity and the other two of negative parity. The present study extended spins upto 19− in the main negative parity band. A new band is populated in the present work and is similar to the one observed in106Ag.
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 351 (1995), S. 357-358 
    ISSN: 1434-601X
    Schlagwort(e): 27.60.+j ; 23.20.Lv
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Evidence for the 2+ level in102Sr is obtained from theβ-decay of102Rb, mass separated at the ISOLDE facility. The energy of 126 keV and the collectivity of the 2+→0+ transition indicate that102Sr is a strongly deformed rigid rotor. In addition, a sizeable lifetime is measured for the 94 keV transition in102Y.
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  • 5
    ISSN: 1434-601X
    Schlagwort(e): 23.20.Lv ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract From new measurements, a half-live of 4.2±0.3 s has been clearly established in127Pr. This value confirms our first result [4] and rules out other data [5]. The127Pr activity was produced by bombarding92Mo or94Mo targets with 210 MeV40Ca beams. The mass identification has been made using an ion-guide coupled with an on-line isotope separator. The partial level scheme proposed for127Ce has been deduced from β-gated γ spectra and Xγ- and γγ-coincidences. A new band structure based on a 1/2+ state is established.
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 353 (1995), S. 231-232 
    ISSN: 1434-601X
    Schlagwort(e): 27.60.+j ; 23.20. Lv ; 21.60. Ev
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The level structure of104Ag has been studied through the103Rh (α, 3nγ) reaction at Eα=40 and 45 MeV. The principal features of the proposed level scheme are in agreement with those obtained earlier through heavy ion reaction. Two quasiparttcle-plus-rotor model calculation has been performed, and the results are compared with experimental data.
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 351 (1995), S. 13-18 
    ISSN: 1434-601X
    Schlagwort(e): 21.60.EV ; 23.20.Ck ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The half-lives of seven levels in105Mo have been determined with high precision at the fission-product separator Josef. Theβ-γ-γ triple coincidence method with plastic and BaF2 scintillators was used for a determination of the time between theβ q feeding of a level of interest and itsγ depopulation. A value ofβ q =0.38 (1) for the deformation parameter has been deduced from the half-lives of the first and second excited states. The results of Particle-Rotor model-calculations with the Nilsson parametersκ=0.084 andμ=0.28 support the assignment of the Nilsson orbital [532] 5/2− to the ground state of105Mo.
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  • 8
    ISSN: 1434-601X
    Schlagwort(e): 23.20.Lv ; 27.60.+j ; 21.60.Cs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract An extended level scheme of109Sn is presented showing high-spin states up to Ex≈ 8 MeV and spins up toJπ=(41/2+). Their decay to the 5/2+ ground state has been observed identifying a 12.8 keV 7/2+ → 5/2+ transition. A half-life of T1/2=7(1) ns has been measured for the 17/2+ state atE x =2114 keV. The experimental data are compared with the predictions of shell-model calculations.
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  • 9
    ISSN: 1434-601X
    Schlagwort(e): 21.10.Re ; 23.20.Lv ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract High spin states of117Xe have been investigated by means of in-beam γ-ray spectroscopy using the reaction92Mo(28Si, 2pn) at beam energies of 100 to 120 MeV. The previously known νh11/2 bands are confirmed and the νg7/2 favored-signature band is extended up to 47/2+, in which two band crossings are observed at ħω=0.33 and 0.44 MeV, respectively. Two new positive-parity bands have been established, one of which is most likely the νg7/2 unfavored-signature band. A new transition cascade with irregular level spacings is also observed.
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 352 (1995), S. 247-255 
    ISSN: 1434-601X
    Schlagwort(e): 21.10.Hw ; 27.60.+j ; 23.20.Lv
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract High spin states up toJ=14 and excitation energy up toE *=3076 keV have been observed in the odd-odd nucleus100Tc with the reaction96Zr(7Li, 3n), at bombarding energies between 21 and 31 MeV, by in-beam γ spectroscopy and conversion-electron measurements. A ΔJ=1 negative parity band similar to that observed in theN=57 isotone102Rh, and based on the 8−, 708 keV state has been identified. The observed band can be interpreted in terms of collective core excitations based on a two-quasiparticle state of(πg9/2 ⊗ νh11/2) configuration. Comparison with IBFM-2 calculations have been performed.
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 352 (1995), S. 293-301 
    ISSN: 1434-601X
    Schlagwort(e): 27.60.+j ; 23.20.Lv
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The low-energy level scheme of theN=63 nucleus101Sr has been obtained from a β-decay study of101Rb. The ν[532]5/2 and ν[411]3/2 orbitals are well established as the ground state and a band head at 271.2keV, respectively. The general properties of the level scheme indicate a quadrupole deformation ofβ ≃ 0.4, confirming the unique feature of saturation of deformation inN ≥ 60 Sr isotopes. The energies of theK=3/2 intraband transitions in the odd-neutron neighbours99Sr61 and101Sr63 are very similar. More generally, the identical bands at low spin in98–101Sr nuclei are correlated with the mass-independent moments of inertia in this region.
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  • 12
    ISSN: 1434-601X
    Schlagwort(e): 27.60.+j ; 25.70.Gh
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The level scheme of148Tb has been extended to an excitation energyE x =14.0 MeV and a spinI≈ 38ħ in two experiments with the OSIRIS Comptom suppressed detector array at the HMI Berlin using the reactions122Sn(31P,5n)148Tb at 160 MeV and120Sn(31P,3n)148Tb at 152 MeV.
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  • 13
    ISSN: 1434-601X
    Schlagwort(e): 23.20.Lv ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract High spin levels in119Te have been populated following the96Zr (30Si, α 3n)119Te reaction at a beam energy of 135 MeV. The subsequentγ-ray deexcitation was studied usingγ-ray spectroscopic methods. New levels and several spin and parity assignments up toJ π=55/2− were established. The decay scheme at high-spin exhibits single-particle characteristics associated with the fully aligned ν(h11/2)3 π(g7/2)2 configuration for the 39/2− level, while the 55/2− level could be interpreted as fully aligned π(d5/2)2 ν h 11 2/5 g 7 2/−2 ) configuration.
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 352 (1995), S. 373-390 
    ISSN: 1434-601X
    Schlagwort(e): 21.10.Sf ; 21.60.Cs ; 23.20.-g ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The neutron deficient nuclei98Ag,104Sn withT z =2 and103In,105Sn (T z=5/2) were studied in-beam following the reaction of 250 MeV58Ni+50Cr. Neutron and charged particle (p, α) gatedγγ-coincidence spectra were used to identify these nuclei, which are populated with yields between 0.05% and 2% of the total residue cross section, and to determine their level schemes. In a comprehensive shell model study various approaches for the residual interaction were used to describe these newly and several previously studied neutron deficient nuclei. As a result predictions for the neutron single particle energies for100Sn are obtained and used to discuss the next generation of experiments.
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 352 (1995), S. 391-395 
    ISSN: 1434-601X
    Schlagwort(e): 21.10.Re ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The band structures of121, 123I nuclei have been studied using a version of the particle-rotor-model in which the experimental excitation energies of the neighbouring (A-1) cores can be fed directly as input parameters. The calculations have been carried out with axially symmetric Nilsson potential with both prolate and oblate deformations. The parameters of the model have been chosen from earlier theoretical work and experimental odd-even mass differences. Only the Coriolis attenuation factor has been treated as adjustable parameter. The theoretical band structures are in very good agreement with the available experimental data.
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 155-174 
    ISSN: 1572-9648
    Schlagwort(e): Shakedown theory ; Cyclic loads ; Structural plasticity ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Nell'ipotesi di piccoli spostamenti e di plasticità perfetta, si studiano le proprietà geometrico-meccaniche della frontiera del dominio dei carichi di adattamento. Si mostra come, nello spazio dei carichi, la suddetta frontiera giuoca il ruolo di superficie di plasticizzazione ed un particolare vettore di deformazione plastica accumulata—che caratterizza il meccanismo di non adattamento—segue la legge della normalità, mentre una forma specifica del teorema del massimo lavoro plastico costituisce un valido strumento per la valutazione del carico limite corrispondente ad un dato meccanismo di non adattamento. Si forniscono altresì le equazioni che governano lo stato della struttura al limite di adattamento, mostrando la capacità del relativo meccanismo di collasso a rappresentare la risposta a lungo termine della struttura a dei carichi periodici inviluppanti il dominio dei carichi con una intensità un poco al di sopra del limite di adattamento.
    Notizen: Abstract In the hypothesis of small displacements and combined time-variable/steady loads, the geometrical-mechanical properties of the shakedown load boundary are investigated. It is shown that, in the load space, the shakedown load boundary plays the role of yield surface, and that a certain plastic strain accumulation vector—characterizing some impending inadaptation collapse mechanism—obeys the normality rule, whereas a specific form of the maximum plastic work theorem constitutes an effective tool for the evaluation of the shakedown limit load corresponding to a specified inadaptation collapse mode. The equations governing the state of the structure at the shakedown limit are provided and the related collapse mechanism is shown to specify the shape of the steady-state response of the structure to a periodic load enveloping the load domain with an intensity slightly above the shakedown limit.
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 417-424 
    ISSN: 1572-9648
    Schlagwort(e): Mohr's circles ; Stress representation ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Si ottiene la classica rappresentazione di O. Mohr dello stato tensionale con i metodi del calcolo di estremi condizionati.
    Notizen: Abstract The classical representation of the stress state due to O. Mohr is obtained by using the calculus of constrained extrema.
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  • 18
    ISSN: 1572-9648
    Schlagwort(e): Electron microscopy ; Microstructures ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Si presentano i risultati di alcuni studi fatti attraverso la microscopia elettronica sulle microstrutture relative a transizioni di fase in una varietà di materiali. I casi comprendono leghe binarie e ternarie, superconduttori TC e materiali C60 e C70; le transizioni esaminate sono diffusionali, displacive o di entrambi i tipi.
    Notizen: Abstract In this contribution the results of some electron microscopy studies on microstructures related with phase transitions in a variety of materials will be presented. The materials include binary and ternary alloys, high TC superconductors as well as C60 and C70 fullerenes, while the transitions can be diffusional, displacive or both.
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 449-458 
    ISSN: 1572-9648
    Schlagwort(e): Lattice ; Nonlinear waves ; Ferroelasticity ; Phase transformations ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Si propone un modello reticolare che può descrivere complessi arrangiamenti fatti di domini elastici ed interfacce. Sulla base di un modello bidimensionale in cui sono presenti interazioni contrastanti e nonlineari si esamina la dinamica della formazione di microstrutture. L'accento è posto sui meccani'smi di instabilità che determinano bande di deformazione localizzata. Si studia l'influenza delle forze applicate e degli effetti dissipativi sulla dinamica di due bande perpendicolari e si interpretano i risultati come un microtwinning in leghe cristalline. Si verificano le congetture fisiche per mezzo di simulazioni numeriche del modello microscopico.
    Notizen: Abstract With the view of understanding how precise macroscopic properties of a material emerge from the underlying physics of homogeneous microstructures, a lattice model which can describe complex non-linear patterns made of elastic domains and interfaces is proposed. On the basis of a two-dimensional lattice model involving non-linear and competing interactions the dynamics of microstructure formation is examined. The emphasis is placed especially on an instability mechanism of a strain band producing localized domains. The influence of applied forces and dissipative effects on the dynamics of two perpendicular strain bands is studied. The results are interpreted as a microtwinning in crystalline alloys. The physical conjectures are checked by means of numerical simulations performed directly on the microscopic system.
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 439-448 
    ISSN: 1572-9648
    Schlagwort(e): Martensitic transformation ; Atomistic simulation ; Phonon localization ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario L'articolo discute un modello ‘Embedded Atom’ per l'energia potenziale di leghe Ni-Al. Il potenziale viene utilizzato in uno studio di Dinamica Molecolare e nell'approssimazione Quasi Armonica della Transformazione Martensitica (MT) che ha luogo in Ni x Al1−x per 0.61〈x〈0.64 a una temperatutaT M compresa tra ~ 0 K perx=0.61 e ~ 400 K perx=0.64. La temperature di transizione è determinata in funzione della composizione e della pressione. I risultati dimostrano la validità del potenziale nel riprodurre le proprietà note della lega. Il modello viene utilizzato per studiare la dinamica microscopica alla base della trasformazione. Lo studio mostra che nella austenite il disordine chimico legato alla non-stechiometria induce bande di fononi localizzati che si delocalizzano in modo discontinue allaMT. Viene mostrato che i modi localizzati sono associati a regioni rieche di Ni ed individuano siti di incipiente instabilità reticolare. Tali siti forniscono centri preferenziali per la nucleazione.
    Notizen: Abstract We discuss an atomistic model for the potential energy of Ni-Al alloys based on the Embedded Atom Method. The potential is applied in a Molecular Dynamics and Quasi Harmonic investigation of the Martensitic Transformation (MT) that occurs in Ni x Al1− x for compositions 0.61〈x〈0.64 at a temperatureT M ranging from ~ 0 K atx=0.61 to ~ 400 K atx=0.64. We determine the transition temperature as a function of composition and pressure and we show that our potential reliably reproduces the known properties of the alloy. We exploit the model to investigate the microscopic dynamical properties underlying the transition. Our computation shows that in the austenite the compositional disorder induces several bands of localized phonons, that discontinuously de-localize at the MT. We show that specific localized modes associated with Ni-rich clusters identify regions of incipient lattice instability, and provide favourable sites for the nucleation.
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 459-466 
    ISSN: 1572-9648
    Schlagwort(e): Shape memory alloys ; Titanium-nickel ; Pseudoelasticity ; Martensitic transformation ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Per leghe Ti-Ni con memoria di forma vengono analizzati i cicli di isteresi isotermici tensione-deformazione prodotti da una incompleta trasformazione martensitica. Gli esperimenti mostrano l'esistenza di due distinte linee di snervamento per la transizione di fase, una verso la trasformazione austenite→martensite (A→M), l'altra per la trasformazione inversa M→A. Il comportamento a trazione di un singolo cristallo con una sola linea di snervamento (A↔M) [1], può essere considerato un caso ideale. L'estensione ad un modello termodinamico pseudo-elastico [2] consente di analizzare queste due linee di snervamento.
    Notizen: Abstract The stress-strain isothermal hysteresis loops due to the incomplete martensitic transformation are analysed for Ti-Ni shape memory alloys. Experiments show the existence of two distinct yield lines for phase transition; one for the forward transformation austenite→martensite (A→M), the other for the reverse transformation M→A. The tensile behaviour of single crystals with only one yield line (A↔M) [1] can be considered as an ‘ideal’ case. An extension of a thermodynamic model for pseudoelasticity [2] allows these two yield lines to be taken into account.
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 505-526 
    ISSN: 1572-9648
    Schlagwort(e): Young measures ; H-measures ; Microstructures ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Si discutono le misure di Young e le loro limitazioni. Alcune relazioni che intercorrono tra le misure di Young e le H-misure sono descritte ed utilizzate nello studio di un esempio tratto dalla meccanica di mezzi micromagnetici. Si evidenzia in particolare la necessità di migliorare la teoria delle H-misure e di altre misure semi-classiche.
    Notizen: Abstract Young measures and their limitations are discussed. Some relations between Young measures and H-measures are described and used to analyze an example from micromagnetics. The need to improve H-measures and semi-classical measures is stressed.
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 495-503 
    ISSN: 1572-9648
    Schlagwort(e): Martensitic transformation ; Shape memory alloys ; Transformation kinetics ; Phase transformations ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Con l'acronimo di SMART (step-wise martensite to austenite reversible transformation) si indica una trasformazione martensitica termoelastica in cui la cinetica di trasformazione risulta modificata dall'esecuzione di un'appropriata procedura di ciclaggio termico parziale (procedura ICH — Incomplete Cycle on Heating) nell'intervallo di temperatura in cui ha luogo la trasformazione martensitica inversa. Vengono qui presentati i risultati sperimentali relativi sia alla SMART sia agli effetti indotti dalla procedure ICH e responsabili delle modifiche della cinetica di trasformazione. Vengono inoltre discusse le ipotesi sino ad ora avanzate per spiegare i risultati sperimentali.
    Notizen: Abstract The step-wise martensite to austenite reversible transformation (SMART) in shape memory alloys (SMA) is a martensitic thermoelastic transformation where a step-wise kinetics is induced by a partial cycling procedure within the hysteresis cycle (incomplete cycle on heating (ICH) procedure). The ICH procedure has been proved effective in inducing a reversible microstructural modification of the martensitic phase. Results till now obtained both on the SMART behaviour and on the effects of the ICH procedure are reviewed here: the hypotheses advanced till now are discussed to explain experimental evidences.
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 475-494 
    ISSN: 1572-9648
    Schlagwort(e): Thermodynamical potential ; Nonconvex energy ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario II lavoro suggerisce una possibile classificazione dei potenziali termodinamici per sistemi con due variabili di stato soggetti a transizioni di fase e, per ogni classe individuata, mostra le caratteristiche e i diagrammi tipici dell'energia interna, l'entalpia, le energie libere di Helmholtz e Gibbs. Potenziali termodinamici a più valori appaiono essere la regola più che l'eccezione. Nell'ambito della classificazione trovata sono studiati vari esempi noti, come il gas di van der Waals e il modello di Landau-Devonshire.
    Notizen: Abstract We suggest here a possible classification of the thermodynamical potentials for phase transition systems with two state variables. Within each of the single-typed classes, the characters and typical diagrams of the internal energy, enthalpy, Helmholtz and Gibbs free energy are shown. Multivalued potentials appear to be the rules rather than the exceptions. Several known examples of phase transitions, e.g. van der Waals gas, Landau-Devonshire model, are studied within the framework of the present classification.
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 527-539 
    ISSN: 1572-9648
    Schlagwort(e): Microstructures ; Shape memory alloys ; Variational methods ; Surface energy ; Phase transformations ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Certe leghe come quelle di In-Tl, Ni-Ti, Ag-Cd o Cu-Al-Ni mostrano proprietà meccaniche notevoli quali la memoria di forma o la pseudoelasticità. Questo comportamento è determinato da una trasformazione di fase solido-solido che conduce a complicati arrangiamenti a livelo microscopico. In studi recenti tali microstrutture sono state analizzate attraverso la minimizzazione dell'energia elastica. Noi discutiamo l'influenza di termini addizionali di energia superficiale sull'esistenza di microstrutture in uno stato naturale sia in un contesto lineare che non lineare.
    Notizen: Abstract Certain alloys such as In-Tl, Ni-Ti, Ag-Cd or Cu-Al-Ni display remarkable mechanical properties such as the shape memory effect or pseudo-elasticity. This behaviour is related to a solid-solid phase transformation which leads to a complicated microscopic arrangement of different phases. In recent studies such microstructures have been analyzed by the minimization of elastic energy. We discuss the influence of additional surface energy terms on the existence of stress-free microstructures both in the nonlinear and a geometrically linear setting.
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 541-565 
    ISSN: 1572-9648
    Schlagwort(e): Phase transitions ; Hysteresis ; Order-parameter ; Nonlocal equations ; Phase transformations ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Il lavoro descrive due tipi di regolarizzazione del problema quasistatico per un potenziale con due minimi in una dimensione. Un modello evidenzia caratteri di non località spaziale, mentre l'altro conduce ad una teoria con parametro d'ordine. Si derivano alcuni risultati di esistenza e regolarità e si presentano alcuni studi numerici che mostrano l'isteresi e il moto delle frontiere tra le fasi.
    Notizen: Abstract The paper describes two types of regularization to the basic quasistatic double-well potential problem in one space dimension. One model features a spatially nonlocal term while the other incorporates the use of an order parameter. Some basic existence and regularity results for these modified models are derived and some numerical calculations that show hysteresis and motion of phase boundaries are presented.
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 567-575 
    ISSN: 1572-9648
    Schlagwort(e): Incoherent phase transitions ; Vacancy diffusion in solids ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario In questo lavoro viene presentato un adattamento del modello di transizione di fase incoerente sviluppato da Gurtin e Cermelli in [3]. Una transizione incoerente è sempre associata alla produzione di un qualche tipo di difetto all'interfaccia: consideriamo qui un modello semplificato di continuo unidimensionale, in modo da poter studiare l'effetto dei difetti di volume (lacune) sull'evoluzione del sistema.
    Notizen: Abstract We present here a simplified version of the model of incoherent solid-solid transitions with mass diffusion developed by Gurtin and Cermelli in [3]. An incoherent phase change is always associated with some kind of defect production at the interface: we consider here a one-dimensional continuum, so that the resulting equations allow study to be made of the influence of volume (vacancy) production on the evolution of the system.
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 591-603 
    ISSN: 1572-9648
    Schlagwort(e): Imperfection sensitivity ; Hysteresis ; Local minimizers ; Variational methods ; Phase transformations ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Si deducono i classici risultati di Stoner e Wohlfarth dalla teoria del micromagnetismo, e si dimostra la loro validità per la previsione di cicli di isteresi magnetica anche per particelle di forma non ellissoidale. Viene proposta, quale possibile spiegazione della notevole ampiezza dei cicli di isteresi caratteristici di particelle di piccole dimensioni, l'indifferenza alla presenza di rugosità superficiale.
    Notizen: Abstract The classical results of Stoner and Wohlfarth for the prediction of hysteresis loops in small ferromagnetic particles are extended to specimens of non-ellipsoidal shape, and shown to be a consequence of micromagnetics. The insensitivity to surface roughness is proposed as a possible explanation of the high coercivity behavior of small particles.
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 621-627 
    ISSN: 1572-9648
    Schlagwort(e): Liquid crystals ; Smectics ; Nematics ; Continuum models ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario I cristalli liquidi smettici sono quasi-solidi che possiedono una microstruttura sia di tipo materiale che locale (la microstruttura nematica e le lamelle, rispettivamente). Essi esibiscono anche transizioni di fase: smettici B a smettici A, a nematici, a liquidi isotropi. Il loro studio, sebbene speciale, potrebbe evidenziare vantaggi generali e difetti di vari tipi di modelli matematici. Qui, nel provare la proprietà annunciata nel titolo, si prepara il lavoro di base per il modello continue.
    Notizen: Abstract Smectic liquid crystals are quasi solids, which possess microstructure both of the material and local type (the nematic mictrostructure and the lamellae, respectively). They also exhibit phase transitions: from smectic B to smectic A, to nematic, to isotrtopic liquid (see [1], Ch. 7). Their study, though special, might show up general advantages and drawbacks of different types of mathematical models. Here, while intent on proving the property announced in the title, we set forth the groundwork for the continuum model (see, in a more specific and concrete mode [2]).
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 629-640 
    ISSN: 1572-9648
    Schlagwort(e): Liquid crystals ; Magnetostrictive solids ; Continua with microstructure ; Phase transformations ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Si discutono equazioni di evoluzione per cristalli liquidi e per solidi magnetostrittivi nell'ambito di una teoria dei continui con microstruttura che contempla la possibilità sia di autointerazioni meccaniche che di termini inerziali non standard.
    Notizen: Abstract Evolution equations for liquid crystals and for magnetostrictive solids are discussed within the framework of a theory of continua with microstructure that allows for mechanical self-interactions and non-standard inertial terms.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 605-619 
    ISSN: 1572-9648
    Schlagwort(e): Thermoelasticity ; Dynamics ; Configurational forces ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Si osserva preliminarmente che, per alcune trasformazioni di fase nei solidi, la più naturale descrizione del fenomeno nell'ambito del continuo sembra essere quella basata sul moto inverse in dinamica, o sulla deformazione inversa in statica. In tale quadro, la nozione di ‘coerenza di fase’, suggerita dalla congruenza geometricocinematica tra due distinti reticoli cristallini a contatto, trova la sua espressione più significativa nella condizione di continuità degli ‘spostamenti di siti’ nel riferimento cristalline. Sulla base di argomentazioni svolte in precedenti lavori dagli autori per il caso dinamico e da M. Epstein per il caso statico e termostatico, si presuppone valida un'equazione di bilancio ‘materiale’: quella dellapseudo-quantità di moto. Si richiede che tale bilancio sia soddisfatto attraverso una superficie di contatto tra le due fasi. Tale superficie o fronte, avanzando, determina la trasformazione del materiale da una fase nell'altra. Il fronte è suppostoomotermo ed il materiale termoelastico in ciascuna delle due fasi. Un ruolo chiave è svolto dal tensore degli sforzi materiali di Eshelby. Infatti, la potenza sviluppata dalle forze di disomogeneità attraverso il fronte che avanza è unicamente determinata dalla discontinuità del tensore di Eshelby lungo la normale al fronte. Inoltre, l'espressione che detta potenza assume permette di evidenziare una quantità scalare che proponiamo di denominareforza configurazionale di Hugoniot-Gibbs per le analogie che essa suggerisce. Si sviluppa infine una trattazione parallela sulla base di una formulazione termodinamica classica del continuo. Un confronto dei risultati permette di Stabilire che la potenza sviluppata dalla forza configurazionale viene dissipata mentre il fronte avanza.
    Notizen: Abstract First we recognize that the coherence of certain phase transformations in solids is most vividly expressed using the material manifold and within the kinematic continuum description based on the so-calledinverse motion. In this fully dynamical framework the equation of interest is theun-balance of pseudomomentum for thermoelastic conductors. On computing the power developed by the accompanying surface source of quasi-inhomogeneities at the phase-transition front, we show that this relates directly to the normal jump of the Eshelby stress — devoid of any kinetic energy, but computed from the free energy — a scalar quantity which may be referred to as theHugoniot-Gibbs configurational force at the front. The thermodynamic analysis also establishes that this power is dissipated as the material progresses at the front that ishomothermal. The jump relation including this dissipation is that associated with the heat propagation equation valid at regular points. In all, this approach is based on the theory of material uniformity and inhomogeneities as developed in recent years by M. Epstein and the authors. All reasonings are made in full dynamics, for finite strains, and any anisotropy in three dimensions.
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 577-589 
    ISSN: 1572-9648
    Schlagwort(e): Microstructures ; Interface energy ; Non convex variational problems ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Il lavoro riguarda la non unicità messa in luce da J.L. Ericksen nella sua analisi dell'equilibrio di barre elastiche con energia non convessa. Seguendo le linee di precedenti lavori, per investigare questa degenerazione si ricorre ad una regolarizzazione del problema e si dà un esplicito quadro di riferimento per lo studio della ricca varietà delle microstrutture di scala finita e della loro stabilità. Si chiarisce in particolare il ruolo dell'energia di interfaccia nella creazione di microstrutture di scala finita considerando l'effetto combinato di termini inibitori e favorevoli all'insorgere di oscillazioni nel funzionale energia.
    Notizen: Abstract This paper addresses the non-uniqueness pointed out by Ericksen in his classical analysis of the equilibrium of a one-dimensional elastic bar with non-convex energy [1]. Following some previous work in this area, we suitably regularize the problem in order to investigate this degenerancy. Our approach gives an explicit framework for the the study of the rich variety offinite-scale equilibrium microstructures for the bar in a hard loading device, and their stability properties. In this way we clarify the role of interfacial energy in creating finitescale microstructures, by considering the combined effect of the oscillation-inducing and oscillation-inhibiting terms in the energy functional.
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 641-663 
    ISSN: 1572-9648
    Schlagwort(e): Polycrystal ; Rate-independent plasticity ; Texture ; Phase transformations ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Proponiamo un modello che collega la deformazione macroscopica all'evoluzione della tessitura cristallina. Questo modello si rifà a variabili microstrutturali per descriverelo stato ‘profondo’ del policristallo; le velocità di tali variabili entrano nell'espressione della potenza virtuale in uno con le microtensioni ad esse associate. Termini supplementari appropriati appaiono inoltre nelle equazioni di bilancio dell'energia e dell'entropia. Viene utilizzato il criterio di Schmid per i singoli sistemi di scivolamento per scrivere una delle equazioni costitutive necessarie. Viene quindi introdotto un assunto simile al criterio di Taylor-Bishop-Hill per i policristalli per mettere in relazione il gradiente di velocità e la velocità di rotazione del reticolo cristallino via la combinazione di scivolamenti attiva. Il modello viene applicato ad un esempio mostrando buon accordo con un policristallo piano alla Taylor per una scelta particolare dei legami costitutivi delle microtensioni.
    Notizen: Abstract We propose a model which links macroscopic deformations with changes in crystalline texture. The model calls upon microstructural variables to describe the state of the polycrystal; their time-rates, together with the corresponding microstresses, enter the expression of virtual power. Appropriate supplementary terms also appear in the equations of balance of energy and entropy. Schmid's law for single slip systems is invoked to provide one of the additional constitutive equations. A constitutive statement similar to the Taylor-Bishop-Hill criterion for polycrystals is introduced to relate the velocity gradient and the lattice spin via the active spin combination. The model is applied to an example agreeing with a Taylor planar polycrystal for a particular choice of constitutive laws for the microstresses.
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Meccanica 30 (1995), S. 467-474 
    ISSN: 1572-9648
    Schlagwort(e): Pseudoelasticity ; Coherency ; Hysteresis ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Nella modellazione delle trasformazioni martensitiche gioca un ruolo essenziale la rappresentazione dell'energia di coerenza tra le fasi. Seguendo una recente proposta di Rogers, in questo lavoro si investiga una forma di tale energia che dipende dalla deformazione di trasformazione.
    Notizen: Abstract In some previous papers [1], [2] pseudoelasticity in tensile experiments has been treated thermodynamically under the assumption that the relevant constitutive ingredients are (i) a non-convex free energy; (ii) coherency between the austenitic and martensitic phase. The form of the coherency energy was assumed to be proportional to the product of phase fractions of the two phases. Recently Rogers [3] has proposed a slight variation of this ansatz: The factor of proportionality should depend on the transformation strain. This new form of coherence energy is investigated in this paper. An attractive feature of this new assumption is that the strains of the coexisting phases in equilibrium remain unchanged as the transformation proceeds. The entropy production inside the pseudoelastic hysteresis is explored for various straight (P, d)-curves.
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  • 35
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 33 (1995), S. 33-38 
    ISSN: 1573-0530
    Schlagwort(e): 17B37 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract We show that the algebra of the bicovariant differential calculus on a quantum group can be understood as a projection of the cross-product between a braided Hopf algebra and the quantum double of the quantum group. The resulting super-Hopf algebra can be reproduced by extending the exterior derivative to tensor products.
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 33 (1995), S. 183-186 
    ISSN: 1573-0530
    Schlagwort(e): 16W30 ; 17Bxx ; 17B05 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract We give a complete classification of the class of connected, simply connected Lie groups whose coadjoint orbits are of dimension smaller or equal to two.
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  • 37
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 33 (1995), S. 221-229 
    ISSN: 1573-0530
    Schlagwort(e): 81R50 ; 17B37
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract We calculate the Clebsch-Gordan coefficients of SUq(2) by a Woronowicz integration over the group manifold and obtain a representation differing from that reached by working with theq-group algebra. These apparently different results must agree, however, and their equivalence implies aq-identity. On lettingq = 1, we shall obtain two results of different structures for the Clebsch-Gordan coefficients of SU(2) and their equivalence similarly implies an identity among the usual binomial coefficients. With the same approach, one may extend the Woronowicz integral of the product of two irreducible representations to products of many irreducible representations.
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 33 (1995), S. 283-295 
    ISSN: 1573-0530
    Schlagwort(e): 81T05 ; 81R50 ; 81S05
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract Fock representations for quantum fields which obey generalized statistics are explicitly constructed. The main features of these representations are investigated.
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 34 (1995), S. 77-90 
    ISSN: 1573-0530
    Schlagwort(e): 16E40 ; 16W30 ; 17B37 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract Cohomology and deformation theories are developed for Poisson algebras starting with the more general concept of a Leibniz pair, namely of an associative algebraA together with a Lie algebraL mapped into the derivations ofA. A bicomplex (with both Hochschild and Chevalley-Eilenberg cohomologies) is essential.
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 33 (1995), S. 207-219 
    ISSN: 1573-0530
    Schlagwort(e): 81R50 ; 17B37 ; 58A50 ; 81Q60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract By investigating the symplectic geometry and geometric quantization of a class of supermanifolds, we exhibit BRST structures for a certain kind of algebras. We discuss the undeformed andq-deformed cases in the classical as well as in the quantum cases.
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  • 41
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 33 (1995), S. 231-240 
    ISSN: 1573-0530
    Schlagwort(e): AMS classification 17B37 ; 16W30 ; 22D05 ; 46H99 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract Using the duality and the topological theory of well-behaved Hopf algebras, we construct star-product models of noncompact quantum groups from Drinfeld and Reshetikhin standard deformations of enveloping Hopf algebras of simple Lie algebras. Our star-products act not only on coefficient functions of finite-dimensional representations, but actually on allC ∞ functions, and they even exist for nonlinear (semi-simple) Lie groups.
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  • 42
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 35 (1995), S. 91-97 
    ISSN: 1573-0530
    Schlagwort(e): 81R50 ; 14M15 ; 14M17
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract Associated to the standard SU q (n) R-matrices, we introduce quantum spheresS q 2n-1 , projective quantum spaces ℂℙ q n-1 , and quantum Grassmann manifoldsG k(ℂ q n ). These algebras are shown to be homogeneous spaces of standard quantum groups and are also quantum principle bundles in the sense of T. Brzeziński and S. Majid.
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  • 43
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 35 (1995), S. 135-143 
    ISSN: 1573-0530
    Schlagwort(e): 17B35 ; 17B37 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract New systems of Laplace (Casimir) operators for the orthogonal and symplectic Lie algebras are constructed. The operators are expressed in terms of paths in graphs related to matrices formed by the generators of these Lie algebras with the use of some properties of the noncommutative symmetric functions associated with a matrix. The decomposition of the Sklyanin determinant into a product of quasi-determinants play the main role in the construction. Analogous decomposition for the quantum determinant provides an alternative proof of the known construction for the Lie algebra gl(N).
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  • 44
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 35 (1995), S. 303-311 
    ISSN: 1573-0530
    Schlagwort(e): 81R50 ; 16W30 ; 58B30
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract There are only two quantum group structures on the space of two by two unimodular matrices, these are the SL q (2) and the SL h (2) quantum groups. The differential geometry of SL q (2) is well known. In this Letter, we develop the differential geometry of SL h (2), and show that the space of left invariant vector fields is three-dimensional.
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  • 45
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 33 (1995), S. 273-281 
    ISSN: 1573-0530
    Schlagwort(e): 17B37 ; 81R50 ; 16W30
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract An embedding method to getq-deformations for the nonsemisimple algebras generating the motion groups ofN-dimensional flat spaces is presented. This method gives a global and simultaneous scheme ofq-deformation for all iso(p, q) algebras and for those obtained from them by some Inönü-Wigner contractions, such as theN-dimensional Euclidean, Poincaré, and Galilei algebras.
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  • 46
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 33 (1995), S. 297-302 
    ISSN: 1573-0530
    Schlagwort(e): 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract We study the possibility of defining the (braided) comultiplication for the GL q (N)-covariant differential complexes on some quantum spaces. We discover suchdifferential bialgebras (and Hopf algebras) on the bosonic and fermionic quantum hyperplanes (with additive coproduct) and on the braided matrix algebra BM q (N) with both multiplicative and additive coproducts. The latter case is related (forN = 2) to theq-Minkowski space andq-Poincaré algebra.
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  • 47
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 34 (1995), S. 1-8 
    ISSN: 1573-0530
    Schlagwort(e): 17B37 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract A quantum analogue of the dual pair $$\mathfrak{s}\mathfrak{l}_2 ,\mathfrak{o}_n $$ is introduced in terms of the oscillator representation of U q $$(\mathfrak{s}\mathfrak{l}_2 )$$ . Its commutant and the associated identity of Capelli type are discussed.
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  • 48
    Digitale Medien
    Digitale Medien
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    Letters in mathematical physics 34 (1995), S. 25-36 
    ISSN: 1573-0530
    Schlagwort(e): 81R50 ; 70G50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract Multiparameter quantum gl(N) is not a rigid structure. This Letter defines an essential deformation as one that cannot be interpreted in terms of a similarity transformation, nor as a perturbation of the parameters. All the equivalence classes of first-order essential deformations are found, as well as a class of exact deformations. This work provides quantization of all the classical Lie bialgebra structures (constantr-matrices) found by Belavin and Drinfeld for sl(n). A special case, that requires the Hecke parameter to be a cubic root of unity, stands out.
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 35 (1995), S. 123-134 
    ISSN: 1573-0530
    Schlagwort(e): 81T40 ; 81R10 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract We study the monodromy representationsℬ k,Iof the mapping class groupℬ 4 acting on 4-point blocks satisfying the Knizhnik-Zamolodchikov equation for the levelk su2 current algebra. We classify all irreducibleℬ k,Iwhich are realized by finite groups; we also display finite irreducible components for the reducible representations corresponding tok = 10.
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 35 (1995), S. 179-185 
    ISSN: 1573-0530
    Schlagwort(e): 17B37 ; 33D80 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract New coherent states of theq-Weyl algebraAA † −qA † A = 1,0 〈q 〈 1, are constructed. They are defined as eigenstates of the operatorA † which is the lowering operator for nonhighest weight representations describing positive energy states. Depending on whether the positive spectrum is discrete or continuous, these coherent states are related either to the bilateral basic hypergeometric series or to some integrals over them. The free particle realization of theq-Weyl algebra whenA † A ∞ d2/dx2 is used for illustrations.
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 35 (1995), S. 221-227 
    ISSN: 1573-0530
    Schlagwort(e): 81R50 ; 81S05 ; 81P99
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract We obtain the complete set of states of theq-oscillator in both configuration space and momentum space as well as the transformation between these spaces. The states as well as the matrix elements lie in the SU q (2) algebra. To obtain transition probabilities, one must take the ‘Woronowicz square.’
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 33 (1995), S. 263-272 
    ISSN: 1573-0530
    Schlagwort(e): 17B37 ; 81R50 ; 17A70
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract TheZ 2 graded Yangian Yq(gl(M |N)) associated with the Perk-SchultzR matrix is introduced. Its structural properties, the central algebra in particular, are studied. AZ 2-graded associative algebra epimorphism Yq(gl(M |N)) → Uq (gl(M |N)) is obtained in explicit form. Images of central elements of the quantum super-Yangian under this epimorphism yield the Casimir operators of the quantum supergroup Uq(gl(M |N)) constructed in an earlier publication.
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 34 (1995), S. 37-48 
    ISSN: 1573-0530
    Schlagwort(e): 16S32 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract The two-dimensional Euclidean quantum algebra is considered at roots of unity. The algebraic properties and the Poisson-Hopf structure are first investigated. We then determine the irreducible representations and study the reduction of the tensor product of two of them.
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 34 (1995), S. 275-283 
    ISSN: 1573-0530
    Schlagwort(e): 81P99 ; 81R50 ; 81S05
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract Although there is no empirical motivation for replacing the commutators of dynamically conjugate operators in quantum mechanics byq-commutators, it appears possible to construct a consistent mathematical formulism based on this idea. To examine such a possibility further, we have studied the relation of this proposal to the Schwinger action principle, since the entire quantum mechanical formulism may be inferred from this principle. In particular, we have discussed the quantum transformation theory within this framework.
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 34 (1995), S. 333-341 
    ISSN: 1573-0530
    Schlagwort(e): 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract We show that the differential complex Ω B over the braided matrix algebra BM q (N) represents a covariant comodule with respect to the coaction of the Hopf algebra Ω A which is a differential extension of GL q (N). On the other hand, the algebra Ω A is a covariant braided comodule with respect to the coaction of the braided Hopf algebra Ω B . Geometrical aspects of these results are discussed.
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  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 35 (1995), S. 163-177 
    ISSN: 1573-0530
    Schlagwort(e): 81T05 ; 81R05 ; 81R50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract We investigate the notion of secondR-quantization - a suitable deformation of the standard second quantization which properly takes into account the nontrivial exchange properties characterizing generalized statistics. We also perform theR-quantization of a class of unitary one-particle representations relevant for the description of symmetries. The Euclidean covariance of anyons is analyzed within this context.
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  • 57
    ISSN: 1434-601X
    Schlagwort(e): 25.70.Hi ; 23.20.Lv ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Gamma-ray studies of130Te+275 MeV64Ni reaction products have identified yrast states of129Te up to a 33 ns isomer at 2138 keV. Theβ −-decay of 17.7 min129Sb to levels in129Te is elucidated.
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 353 (1995), S. 5-6 
    ISSN: 1434-601X
    Schlagwort(e): 23.20.Lv ; 27.60.+j ; Z
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The structure of the neutron deficient 184 Hg nucleus was investigated using the GASP γ-ray spectrometer.184 Hg nucleus was populated through the156 Gd(32 S,4n) reaction at a beam energy of 163 MeV. Six bands were observed, four of them for the first time. The quadrupole deformations of the two stronger excited bands were measured using the Doppler shift attenuation method.
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  • 59
    ISSN: 1434-601X
    Schlagwort(e): 21.60.Cs ; 21.60.Ev ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Above-yrast states in the one-ptoton nucleus147Tb were studied in144Sm(6Li,3n)γ- and electron-measurements at the Coulomb barrier. Together with data from a separate study of147Dyβ-decay, members of all ten particle×phonon configurations of147Tb were identified, including the completeπh11/2×3− and πs1/2×3− octupole multiplets.
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 352 (1995), S. 1-2 
    ISSN: 1434-601X
    Schlagwort(e): 21.10.Dr ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The Q EC values of the $${}^{148}Tb_{2^ - } $$ ground-state and the $${}^{148}Tb_{9^ + } $$ isomer were measured to the 5750(40) keV and 5846(50) keV, respectively, corresponding to a148Tb ground-state mass-excess of ⦓70527(30) keV. The impact on mass calculations near146Gd is discussed.
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  • 61
    ISSN: 1434-601X
    Schlagwort(e): 21.10.-k ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract High-spin states of148Tb were studied by inbeam γ-ray spectroscopic techniques using141Pr(13C,6n)148Tb and27Al(130Te,9n)148Tb reactions. The level scheme of148Tb was established up to the excitation energy of 11.8MeV. The excitation energy of the high-spin isomer reported previously was revised to be 8.620MeV. The excited states below the isomer could be understood as resulted from the weak couplings of πh11/2 and νf7/2 to those of147Gd and147Tb, respectively.
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  • 62
    ISSN: 1434-601X
    Schlagwort(e): 21.60.Cs ; 23.20.Lv ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The neutron deficient nucleus94Pd was identified and studied for the first time by in-beam spectroscopy. An Iπ=(14+) isomer with t1/2=0.8 (2) μs was observed in a recoil catcher setup inside the multi-detector γ-array OSIRIS. Filter detectors for neutrons and charged particles were used to identify the (2p2n) exit channel of the reaction58Ni+40Ca, populated with only 0.06% of the total evaporation residue cross section. The structure of the isomer is discussed within the frame work of shell model calculations in the (p1/2,g9/2) model space with emphasis on the g 9 2/2 T=0, I=1,9 ”pairing” two-body matrix elements.
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  • 63
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 353 (1995), S. 239-245 
    ISSN: 1434-601X
    Schlagwort(e): 21.10.−k ; 21.60.−n ; 25.70.−z ; 27.60.+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract High spin states of119Te, populated in110Pd(13C, 4n) and110Pd(12C, 3n) reactions, have been studied throughγ-ray spectroscopy. The level scheme has been established up to jπ=(55/2−). Three-quasiparticle states, based onπg 7 2/2 ⊗vh 11/2 andπg 7/2 d 5/2⊗vh 11/2 configurations, have been identified. A particularly favoured 39/2− state is suggested to be the fully aligned [πg 7 2/2 ]6+⊗[vh 11 2/3 ]27/2− yrast non-collective oblate configuration. This assignment is supported by Total Routhian Surface (TRS) calculations which also suggest a similar oblate assignment to states at 21/2−, 23/2− and 37/2−.
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