Contract signature in e-commerce

In this paper, we propose a notion of contract signature used in e-commerce applications. We propose a contract signature scheme based on the discrete logarithm assumption. The contract signature scheme adopts a digital multi-signature scheme in public-key cryptography to facilitate fair signature exchange over network. This proposed solution allows multiple signers of a contract signature to exchange their partial signatures which are fully ambiguous for any third party (i.e., 1 out of ∞ ambiguity) to construct a valid contract signature. In case any signer releases the partial signature to others, the signer does not bind to the contract.     

Applying evidential reasoning methods to agricultural land cover classification

Land cover classification remains an important and complex problem when land observational satellites are involved. Conventional methods of image classification have been shown to provide adequate results; however, when complex surface arrangements are encountered the reliability of conventional approaches can be called into question. This situation is particularly apparent when land cover classes cannot be well discriminated, or when land cover categories are sufficiently broad in their definition that a single spectral response pattern cannot adequately capture the inherent within variation associated with that class. In this paper the problem of agricultural land mapping was examined and the potential for applying soft-classification procedures based on the Dempster-Shafer Theory of Evidence was demonstrated. Results of this study show that applying Dempster-Shafer Theory in image classification can yield thematic maps with accuracies that can support their operational use. In addition, through the application of this technique, a framework can be developed to support and guide the use of subjective judgement during the classification process and permit greater flexibility in the formulation of informational classes.     

Bounded-to-unbounded poker game

The bounded-to-unbounded poker game is a fair poker game that can be played over the Internet. It allows both dealer and player to distribute cards in a fair and secure manner. In addition, the presented protocol assumes that the player is computationally bounded: however, the dealer is computationally unbounded     

Thermal and mechanical properties of LaNbO4-based ceramics

Thermal and mechanical properties of polycrystalline La_1−xA_xNbO₄ (x = 0, 0.005, 0.02 and A = Ca, Sr and Ba) are reported. The materials possess a ferroelastic to paraelastic phase transition close to 500 °C, and the linear thermal expansion is significantly lower (8.6 ± 0.5 × 10⁻⁶ °C⁻¹) for the paraelastic phase compared to the ferroelastic phase (15 ± 3 × 10⁻⁶ °C⁻¹). The hardness was significantly higher for acceptor doped materials (6 GPa) compared to pure LaNbO₄ (3 GPa) due to a significantly smaller average grain size. The fracture toughness of La_0.98Sr_0.02NbO₄, measured by single edge V-notched beam method, was 1.7 ± 0.2 MPa m^1/2 independent of temperature up to 600 °C. The ferroelastic properties of the materials were confirmed by non-linear relationships between stress and strain during compression/decompression, a remnant strain after decompression and the presence of ferroelastic domains. The mechanical properties of LaNbO₄-based materials are discussed with focus on ferroelasticity, microcracking due to crystallographic anisotropy and pinning of ferroelastic domain boundaries.     

Chemical compatibility of proton conducting LaNbO4 electrolyte with potential oxide cathodes

The chemical and physical compatibility of the proton conducting electrolyte material LaNbO₄ with the potential partner materials LaMO₃ (MMn, Fe, Co) and La₂NiO₄ is investigated via the reaction of fine-grained powders and solid-state diffusion couples. Results show generally good chemical compatibility for LaNbO₄ with perovskite type compositions, particularly the LaFeO₃ and LaMnO₃ systems. In contrast, Ruddlesden–Popper type phases are predicted to be poor candidates for use with LaNbO₄. Investigation of the La₂O₃–NiO–Nb₂O₅ and La₂O₃–CoO–Nb₂O₅ phase diagrams finds two new perovskite-related materials of stoichiometry LaNb_1/3M_2/3O₃ (MNi, Co), and indicates coexistence of LaNbO₄ with the binary oxides NiO and CoO. Additionally, reduction of a LaNbO₄–NiO composite confirms coexistence of LaNbO₄ with Ni, and so it is concluded that doped-LaMO₃|LaNbO₄|Ni-LaNbO₄ type electrochemical cells may be manufactured via a direct co-firing route without the formation of secondary phases at inter-phase boundaries.     

Processing of thin film ceramic membranes for oxygen separation

Processing of dense and thin ceramic membrane layers for high temperature selective oxygen separation is addressed in this study. Mixed oxygen-ionic and electronic conducting perovskite oxide system based on La_0.2Sr_0.8Fe_0.8Ta_0.2O_3−δ composition is employed for processing of structural and functional layers. Special focus is aimed at obtaining thin layer and final microstructure with particle size in the sub-micron range. Thin layer deposition is performed by dip coating technique using stable colloidal suspension of perovskite particles dispersed within ethanol media. Two polymer based surfactants were screened for their effect on particle agglomeration and rheological response. By using optimum quantity of 2.5 wt.% addition of selected surfactant it is possible to obtain dense 15-60 μm thick functional layers. The thermal cycle applied resulted in final particle sizes within sub-micron range. By employing suspension with pore former it was possible to significantly increase the surface area of the functional layer.     

Verifying task-based specifications in conceptual graphs

A conceptual model is a model of real world concepts and application domains as perceived by users and developers. It helps developers investigate and represent the semantics of the problem domain, as well as communicate among themselves and with users. In this paper, we propose the use of task-based specifications in conceptual graphs (TBCG) to construct and verify a conceptual model. Task-based specification methodology is used to serve as the mechanism to structure the knowledge captured in the conceptual model; whereas conceptual graphs are adopted as the formalism to express task-based specifications and to provide a reasoning capability for the purpose of verification. Verifying a conceptual model is performed on model specifications of a task through constraints satisfaction and relaxation techniques, and on process specifications of the task based on operators and rules of inference inherited in conceptual graphs.     

Synthesis, densification and electrical properties of strontium cerate ceramics

Powders of pure and 5% ytterbium substituted strontium cerate (SrCeO₃/SrCe_0.95Yb_0.05O_3−δ) were prepared by spray pyrolysis of nitrate salt solutions. The powders were single phase after calcination in nitrogen atmosphere at 1100 °C (SrCeO₃) and 1200 °C (SrCe_0.95Yb_0.05O_3−δ). Dense SrCeO₃ and SrCe_0.95Yb_0.05O_3−δ materials were obtained by sintering at 1350–1400 °C in air. Heat treatment at 850 and 1000 °C, respectively, was necessary prior to sintering to obtain high density. The dense materials had homogenous microstructures with grain size in the range 6–10 μm for SrCeO₃ and 1–2 μm for SrCe_0.95Yb_0.05O_3−δ. The electrical conductivity of SrCe_0.95Yb_0.05O_3−δ was in good agreement with reported data, showing mixed ionic–electronic conduction. The ionic contribution was dominated by protons below 1000 °C and the proton conductivity reached a maximum of 0.005 S/cm above 900 °C. In oxidizing atmosphere the p-type electronic conduction was dominating above 700 °C, while the contribution from n-type electronic conduction only was significant above 1000 °C in reducing atmosphere.     

Analysis of cracked anisotropic plates using the hybrid finite element method

This paper presents a convenient and efficient method to obtain accurate stress intensity factors for cracked anisotropic plates. In this method, a complex variable formulation in conjunction with a hybrid displacement finite element scheme is used to carry out the stiffness and stress calculations of finite cracked plates subjected to general boundary and loading conditions. Unlike other numerical methods used for local analysis such as the boundary element method, the present method results in a symmetric stiffness matrix, which can be directly incorporated into the stiffness matrix representing other structural parts modeled by conventional finite elements. Therefore, the present method is ideally suited for modeling cracked plates in a large complex structure.     

SiGe heterostructure field-effect transistor using V-shaped confining potential well

A working p-type SiGe heterostructure field-effect transistor, utilizing a V-shaped confining potential well as the conducting channel, has been successfully fabricated. The upper boron /spl delta/-doping layer acts as a diffusion barrier to slow diffusion into the undoped Si cap layer. On the other hand, the bottom boron /spl delta/-doping layer prevents hot holes from escaping the channel by improving carrier confinement. It is found that when a V-shaped confining potential well is used as the conducting channel, the devices exhibit the excellent property not only of higher current density but also enhancement in extrinsic transconductance and linear operation range over a wider dynamic range than those of /spl delta/-doped devices for the same dose in SiGe conducting well. The measured transconductance is enhanced three to six times over that of the other /spl delta/ cases.