Null Condition for Semilinear Wave Equation with Variable Coefficients

∗The author was partially supported by M.U.R.S.T. Progr. Nazionale “Problemi Non Lineari...”

Cerami (C) Condition and Mountain Pass Theorem for Multivalued Mappings

Partially supported by Sapientia Foundation.

Groups with the Minimal Condition on Non-“Nilpotent-by-Finite” Subgroups

We characterize the groups which do not have non-trivial perfect sections and such that any strictly descending chain of non-“nilpotent-by-finite” subgroups is finite.

Necessary and Sufficient Condition for Oscillations of Neutral Differential Equation

2000 Mathematics Subject Classification: 34K15, 34C10.

A Necessary and Sufficient Condition for the Existence of an (n,r)-arc in PG(2,q) and Its Applications

ACM Computing Classification System (1998): E.4.

On a Second Order Condition for Max-Semistable Laws

2000 Mathematics Subject Classification: 62G32, 62G20.

Optimum Chemical Balance Weighing Design under Certain Condition

2000 Mathematics Subject Classification: 62K05, 05B05.

Inference of helicopter airframe condition

The goal of this paper is to model normal airframe conditions for helicopters in order to detect changes. This is done by inferring the flying state using a selection of sensors and frequency bands that are best for discriminating between different states. We used non-linear state-space models (NLSSM) for modelling flight conditions based on short-time frequency analysis of the vibration data and embedded the models in a switching framework to detect transitions between states. We then created a density model (using a Gaussian mixture model) for the NLSSM innovations: this provides a model for normal operation. To validate our approach, we used data with added synthetic abnormalities which was detected as low-probability periods. The model of normality gave good indications of faults during the flight, in the form of low probabilities under the model, with high accuracy (>92 %). © 2013 IEEE.

On The Cauchy Problem for Non Effectively Hyperbolic Operators, The Ivrii-Petkov-Hörmander Condition and the Gevrey Well Posedness

2000 Mathematics Subject Classification: 35L15, Secondary 35L30.

Dirac type condition and Hamiltonian graphs

2010 Mathematics Subject Classification: 05C38, 05C45.

Two-phase flow analogy as an effective boundary condition for modelling liquids at atomistic resolution

A hybrid Molecular Dynamics/Fluctuating Hydrodynamics framework based on the analogy with two-phase hydrodynamics has been extended to dynamically tracking the feature of interest at all-atom resolution. In the model, the hydrodynamics description is used as an effective boundary condition to close the molecular dynamics solution without resorting to standard periodic boundary conditions. The approach is implemented in a popular Molecular Dynamics package GROMACS and results for two biomolecular systems are reported. A small peptide dialanine and a complete capsid of a virus porcine circovirus 2 in water are considered and shown to reproduce the structural and dynamic properties compared to those obtained in theory, purely atomistic simulations, and experiment.

A sikeres növekedés és innováció feltételei (The condition of successful growth and innovation)

Kutatásukban a szerzők a sikeres innovációs-növekedési stratégiák beazonosítására törekedtek két dimenzió mentén: növekedési erőfeszítés és innovációs erőfeszítés. A sikert mint a radikális innováció piaci bevezetéseként definiálták. A szakirodalom áttekintése és kvalitatív kutatási eredményeink alapján azt találták, hogy a siker feltételei a következők: (1) „felkészültség”, azaz biztos szakmai tudás (know-what); a (2) „gyakorlás”, azaz a folyamatok tökéletes ismerete (know-how); a (3) „tehetséggondozás”, azaz a megfelelő kapcsolati tőke a hiányzó képességek, erőforrások és információk megszerzéséhez (know-who); és végül a (4) „tehetség”, azaz kreativitás, magas asszociációs készség, és innovatív ötletek. A vezető feladata annak felismerése, hogy mikor szükséges lassítania a szervezetre nehezedő növekedési nyomáson. A nyugalmi időszakban továbbra is fontos az innovációs képességek fejlesztése. Következetesen fel kell ismernie, hogy mikor lesz nagyobb a szétaprózott erőforrások és a megosztott figyelem költsége, mint a potenciális hozadéka. _______ In present research the successful innovation-growth strategies are identified along two dimensions: growth effort and innovation effort. The success is defined as the introduction to the market of a radical innovation. After reviewing the literature and conducting a qualitative research, authors found that the threshold condition of success are the followings: (1) “preparation”, that is expertise (know-what); (2) “practice”, that is deep understanding of processes (know-how); (3) “talent support”, that is access to missing resources; and finally (4) “talent”, that is creativity, innovative idea, and high association capability. This is the role of the manager to decide when the organizational growth should be slowed down. While the development of innovation capability is still important in times of slow growth periods, the manager must recognize that the cost of divided attention and fragmented resources is higher, than the potential return of the innovation.

Social network structure as a critical success condition for open source software project communities

In recent years, a surprising new phenomenon has emerged in which globally-distributed online communities collaborate to create useful and sophisticated computer software. These open source software groups are comprised of generally unaffiliated individuals and organizations who work in a seemingly chaotic fashion and who participate on a voluntary basis without direct financial incentive. ^ The purpose of this research is to investigate the relationship between the social network structure of these intriguing groups and their level of output and activity, where social network structure is defined as (1) closure or connectedness within the group, (2) bridging ties which extend outside of the group, and (3) leader centrality within the group. Based on well-tested theories of social capital and centrality in teams, propositions were formulated which suggest that social network structures associated with successful open source software project communities will exhibit high levels of bridging and moderate levels of closure and leader centrality. ^ The research setting was the SourceForge hosting organization and a study population of 143 project communities was identified. Independent variables included measures of closure and leader centrality defined over conversational ties, along with measures of bridging defined over membership ties. Dependent variables included source code commits and software releases for community output, and software downloads and project site page views for community activity. A cross-sectional study design was used and archival data were extracted and aggregated for the two-year period following the first release of project software. The resulting compiled variables were analyzed using multiple linear and quadratic regressions, controlling for group size and conversational volume. ^ Contrary to theory-based expectations, the surprising results showed that successful project groups exhibited low levels of closure and that the levels of bridging and leader centrality were not important factors of success. These findings suggest that the creation and use of open source software may represent a fundamentally new socio-technical development process which disrupts the team paradigm and which triggers the need for building new theories of collaborative development. These new theories could point towards the broader application of open source methods for the creation of knowledge-based products other than software. ^

Carbon isotopic composition of cypress trees from South Florida and changing hydrologic condition

δ13C values were determined from cypresstree rings from two different study areas in SouthFlorida. One site is located in the Southeastern Everglades Marsh, where pond cypress (Taxodium ascendens) was sampled from tree islands (annual tree rings from 1970 to 2000). Bald cypress (Taxodium distichum) trees were sampled at the other site, located along the Loxahatchee River in a coastal wetland (decadal tree rings from 1830 to 1990). The isotopic time series from both sites display different, location-specific information. The pond cypressisotopic time series has a positive correlation with the total amount of annual precipitation, while the bald cypress data from the Loxahatchee River study area had two different records dependent on the level of saltwater stress. In general, for terrestrial trees growing in a temperate environment, water stress causes an increase in water-use efficiency (WUE) resulting in a relative 13C enrichment. Yet, trees growing in wetland settings in some cases do not respond in the same manner. We propose a conceptual model based on changes in carbon assimilation and isotopic fractionation as controlled by differences in stomatal resistance (water stress) and mesophyll resistance (biochemical and nutrient related) to explain the isotopic records from both sites. With further work and a longer time series, our approach may be tested, and used to reconstruct change in hydroperiods further back in time, and potentially provide a baseline for wetland restoration.