bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Blowing Agent on Cell Morphology and Acoustic Absorption of Natural Rubber Foam
Authors: Harnnarongchai Wanlop , Chaochanchaikul Kantima
Published: October 2015

The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO3) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO3 at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO3 addition.
Surface Modification of Composite Membranes by Coating PVA/TiO2 Layer
Authors: Yalcinkaya Baturalp , Chaloupek Jiri
Published: October 2015

Water pollution comprises all of those compounds that change the quality of groundwater and surface water, therefore reducing the suitability of natural water for human use and other vital processes. These compounds result from human activities, especially those that are industrial, agricultural and domestic.The polyamide thin film composite reverse osmosis membranes become important in desalination of sea water and brackish water or waste water. However the polyamide reverse osmosis membranes tend to fouling due to their hydrophobic and rough surfaces. In this study flux and rejection of waste water from aluminum production industry were obtained during filtration process by using modified commercial composite membranes. Amount of fouling was evaluated with unmodified and modified membranes. Rejection of iron particles and PH of feed and permeate solutions were determined after filtration process. Results shows that modified membranes were performed higher metal ion rejection and antifouling performance than unmodified membranes.
BaSO4/Polyvinyl Alcohol Composites for Radiation Shielding
Authors: Thongpool Voranuch , Phunpueok Akapong , Barnthip Naris , Jaiyen Sarawut
Published: October 2015

The gamma ray and X-ray shielding properties of PVA containing different proportions of BaSO4 as an aggregate have been investigated. The photon linear attenuation coefficients were measured by using 241Am radioactive source (59.54 keV). Gamma rays were counted by a NaI(Tl) detector. It was found that the shielding efficiency increased when increasing the amount of BaSO4 and specimen thickness. The linear attenuation coefficients were 0.085, 0.125, 0.179, and 0.189 for 0.2, 0.4, 0.6, and 0.8%w/v of BaSO4. The X-ray attenuation test was performed using the diagnostic X-ray machine for energy of 45 kVp. The optical density of X-ray films was investigated. The results showed that the optical density of X-ray film decreased when increasing the amounts of BaSO4.
NLARX Model Identification for Grid Tied Inverter Using Genetic Algorithm
Authors: Vacharapanich Viritpol , Pratinthong Naris , Chenvidhya Dhirayut
Published: October 2015

This research studies the parameter identification for establish the model of inverter control system which has grid-connected in distributed power systems. Identification is a method of measuring the mathematical description of a system by processing the observed inputs and outputs of the system. The model developed is based on nonlinear autoregressive with exogenous input (NLARX) for simulate the inverter control system which has grid-connected in distributed power systems. To analyze the model, we use one, three and five steps ahead analysis technique which is the tool in mathematical model analysis for model categories of NLARX. In this research, we present comparative analysis of the model using NLARX in 3 different categories that is wavelet network, tree partition network and sigmoid network. The simulation results show that the optimal category of NLARX is sigmoid network which has one, three and five steps ahead value is equal to 97.01, 91.50 and 88.90 percent respectively from output model and the measured output from the validation data set from grid tied inverter mathematical modelling using genetic algorithm. This optimal model can be used to simulate for analyze trends of the output data which can represent for the real system.
Improving the Evolutionary Computation for General Keyboard Arrangement Problem
Authors: Janthanasub Veerawan , Meesad Phayung
Published: October 2015

Thai traditional computer keyboard layouts are derived from the Thai typewriter keyboard's layout, which supports typing with ten fingers. Hence, this layout is not optimized for typing on touch screen device with one finger. This article presents a new method in arrangement the position of Thai characters on the virtual keyboard to support typing by a single finger. The process of the new method consist of analysing Thai Language to create difference digraph table from Benchmark for Enhancing the Standard of Thai language processing corpus (BEST corpus), designed keyboard layout using evolutionary computation technique and estimated time speed of typing by model human hand movement with Fitts' Law. The experiment shows that new keyboard designed by the proposed method has achieved a typing speed faster than the Thai traditional keyboard layout.
Optical Analysis of Bismuth-Based Glasses Doped Potassium Chromate
Authors: Dutchaneephet Jirapan , Sukprasong Saksit , Sirikulrat Narin , Ngamjarurojana Athipong
Published: October 2015

In this study, Bismuth-based glasses were prepared and doped with various concentration of potassium chromate. They were melted in an electrical furnace at 1250°C for 4 hours then pressed with fire frame to plate shape and annealed at 500°C for 10 min. Optical spectra were used to analyze color shade of glasses. Homogeneity of glasses was analyzed by birefringence technique. Glasses color was changed from colorless to slightly and opaque green with an increasing amount of potassium dichromate and birefringence result showed that the glasses are non-homogenous.
Scintillation Properties of Ce-Doped LuYAP Crystal for Gamma Ray Detection
Authors: Phunpueok Akapong , Thongpool Voranuch , Chewpraditkul Weerapong
Published: October 2015

In the present day, inorganic scintillating crystals become a main part in detection and spectroscopy of nuclear particles and high energy photons, more spectively in X/g-ray imaging. The good properties for the scintillating crystals used in these applications require high photon yield, high stopping power, good energy resolution, good light yield proportionality, and minimal afterglow. The main useful of Ce-doped Lu0.7Y0.3AlO3 (LuYAP(Ce)) are high stopping power and non-hygroscopic which are expected to be key ingredients for medical imaging. In this work, we studied the light yield non-proportionality and energy resolution of LuYAP(Ce) crystal with the energy range from 31 to 1,274.5 keV using photomultiplier tube (PMT) readout. The intrinsic resolution of the LuYAP(Ce) crystal has been determined after correcting the measured PMT resolution. The results showed that the non-proportional response of the crystals was strongly correlated with the intrinsic resolution of the crystals.
Dual Solutions for Unsteady Heat and Mass Transfer in Bio-Convection Flow towards a Rotating Cone/Plate in a Rotating Fluid
Authors: Raju Chakravarthula S.K. , Sandeep Naramgari
Published: October 2015

A mathematical model has been proposed for analyzing the momentum, heat and mass transfer in Bio-convection flow towards a rotating cone/plate in a rotating fluid with nonlinear thermal radiation and chemical reaction. In this study we considered gyrotactic microorganism’s contained Williamson fluid. Numerical results are carried out by using Runge-Kutta based shooting technique. The effects of dimensionless governing parameters on the flow, heat and mass transfer are illustrated graphically. It is also computed the friction factors for the tangential and azimuthal directions, local Nusselt and Sherwood numbers along with the local density of the motile organisms. It has been observed a good agreement of the present results with the existed literature. The obtained results indicate that the heat and mass transfer rate is significantly increases for higher values of buoyancy parameter and Biot number. It is also found that the heat and mass transfer performance in Bio-convection flow is significantly high on the flow over a rotating plate while compared with the rotating cone.
Determining the Quality of Compression in High Resolution Satellite Images Using Different Compression Methods
Authors: Sanjith S. , Ganesan R.
Published: October 2015

Measuring the quality of image is very complex and hard process since the opinion of the humans are affected by physical and psychological parameters. So many techniques are invented and proposed for image quality analysis but none of the methods suits best for it. Assessment of image quality plays an important role in image processing. In this paper we present the experimental results by comparing the quality of different satellite images (ALOS, RapidEye, SPOT4, SPOT5, SPOT6, SPOTMap) after compression using four different compression methods namely Joint Photographic Expert Group (JPEG), Embedded Zero tree Wavelet (EZW), Set Partitioning in Hierarchical Tree (SPIHT), Joint Photographic Expert Group – 2000 (JPEG 2000). The Mean Square Error (MSE), Signal to Noise Ratio (SNR) and Peak Signal to Noise Ratio (PSNR) values are calculated to determine the quality of the high resolution satellite images after compression.
A Proposed Supply Chain Model for Productivity Enhancement in Medium Scale Foundry Industries
Authors: Nallusamy S. , Muhammad Umarmukdhar A.M. , Suganthini Rekha R.
Published: October 2015

In global competitive atmosphere, foundry industries are needed to perform efficiently with minimum percentage of rejections there by reducing cost of manufacturing. Foundries are using state of art processes with the involvement of experienced and knowledgeable people but the experience and knowledge needs to be transformed for the growth of the industries. Some foundries are working in a trial and error mode and get their work done. Many foundries have very less control on the rejections since they are in critical need of meeting production targets and they ignore the rejections and recover the castings. They need to have an efficient quality control aspiring for defects free castings with minimum production cost. Strategic decision makers need extensive models to guide them for efficient decision making that increases their profitability of the entire chain. The noval idea of this research is to investigate the various defects of cast iron foundry and suggest remedies for the defects in a day to day activity and propose a supply chain model to present the necessity of quality in a medium scale industry of cast iron foundry under different delay conditions, rejection rates and also various other factors. The results of the proposed model have been discussed and confirmed based on the original results of an industry. This research is also inspects the relationship between supply chain processes and quality as a key role in supply chain management.
Experimental Validation of Fresh Water Production Using Triangular Pyramid Solar Still with PCM Storage
Authors: Sathyamurthy Ravishankar , Nagarajan P.K. , Vijayakumar D.
Published: October 2015

In the study work effect of PCM on the triangular pyramid solar still was experimentally investigated for the climatic condition of Chennai. Experimental studies were conducted and the use of PCM on storage was compared with a solar still without PCM and the PCM used is paraffin wax. The latent heat energy storage is increased with the use of paraffin wax while the energy stored is utilized during the absence of solar radiation by rejecting its heat through the basin to water for further evaporation. The temperatures of various elements of the solar still were measured using a thermocouple. Results show that there is an increase in productivity of 20% when compared to the solar still without PCM.
Magnetohydrodynamic Convective Double Diffusive Laminar Boundary Layer Flow Past an Accelerated Vertical Plate
Authors: Reddy P. Chandra , Raju M.C. , Raju G.S.S.
Published: October 2015

This manuscript presents the diffusion thermo and thermo diffusion effects on unsteady MHD natural convection heat and mass transfer flow past an accelerated vertical porous plate in the presence of thermal radiation, variable temperature and also variable concentration. The non-dimensional governing equations are coupled non-linear partial differential equations for which the exact solution is not possible. Hence these equations are solved numerically by using finite difference scheme. The effects of different physical parameters involved in the problem are presented and discussed with the help of graphs. The fluid velocity increases with the increasing values of Grashof number, modified Grashof number, Soret number, Dufour number and permeability of the porous medium, but a reverse behavior is found in the case of magnetic parameter and Prandtl number. The fluid temperature falls down for increasing values of radiation parameter, heat sink parameter and Prandtl number, whereas enhancement in the fluid temperature is found in the case of Soret and Dufour effects. Increasing values of Soret number results in rising of the concentration, but it falls down under the influence of Dufour number and Schmidt number.
Characterization of Cellulosic Fibres Properties for their Using in Composites
Authors: Hospodarova Viola , Singovszka Eva , Števulová Nadežda
Published: October 2015

Nowadays, the material recycling is growing trend in development of building materials and therefore using of secondary raw materials for production of new building materials. Transition from application non-renewable sources of raw materials to renewable raw materials in terms of sustainable composite is required. Renewable raw materials include organic sources of raw materials coming from natural plant fibres. This material is used to contribute environmental protection and to save non-renewable resources of raw materials. Wood fibres and cellulose fibres made from waste paper were selected for reinforcing cement-based materials. Application of cellulosic fibres into composites depends on their properties. Therefore, this paper is aimed to study of morphology and properties of cellulosic fibres. The comparison of strength parameters of 28 days hardened composites with 5% adding bleached wood and unbleached recycled fibres with those of reference composite without fibres showed that the values of compressive strength of fibrous cement based specimens were lower by 17 to 29 %.
Particulate Matters Propagation by the Surface Winning
Authors: Lukáčová Katarína , Badida Miroslav , Moravec Marek , Liptai Pavol
Published: October 2015

In surface winning particulate matters are generated from a range of site preparation, stockpiling, loading, transportation and processing activities. This article aims to review issues relevant to particulate matters produced by the surface winning and impact on people living near by the quarry. Due to the areal extent of the site and limitations imposed by readily available data, the article has focused upon activities associated with quarry. On the base of obtained data was composed mathematical model of the distribution of particulate matter from the source to the surroundings to visual impact of the quarry and potential impact of the particulate matters. The visualization is shown direction of particulate matters propagation and allows decide on used measures to eliminate negative impact on people and environment.
Environmental Assessment of the Concrete Based on Blast Furnace Slag
Authors: Ondová Marcela , Vaclavik Vojtech
Published: October 2015

The paper deals with the use of blast furnace slag in the production of plain concrete and with its impact on the elements of the environment. The finely ground granulated blast furnace slag with the weight of 10, 20, 30, 40, 50, 60, 80, 95 and 100 % was used as a substitute of Portland cement in ratio 1:1 of weight. The following properties were observed in all prepared experimental mixtures: consistency of concrete mixture, density of fresh concrete mixture, cube and prism strengths, water tightness, frost resistance and static modulus of elasticity. Subsequently, the life cycle assessment as well as the comparison of environmental impact of selected plain concretes by the LCA method was made. They were monitored total environmental impacts in terms of threats to soil, water, air and human health in order to select the most suitable alternative. The comparison of the reference mixture and mixture with 60% wt. of blast furnace slag showed that using secondary raw materials visibly decreased the impact in each category: Abiotic depletion of 56%; Acidification of 52%; Eutrophication of 56%; Global warming of 58%; Ozone layer depletion of 50%; Terrestrial ecotoxicity of 59%; Photochemical oxidation of 50%, Primary energy (non-renewable fossil) of 53% and of 58% for Human toxicity, Fresh water aquatic ecotoxicity and Marine aquatic ecotoxicity, respectively.
Elimination of Heavy Metals from the Material of Sludge Bed Slovinky
Authors: Kozáková Ľubica , Zeleňák Miroslav , Bakalár Tomáš , Zeleňák Fridrich
Published: October 2015

Old environmental loads are priority environmental problems in Slovakia. An old environmental load is an anthropogenic constituent in landscape which has its origin in past works (for example mining and mineral processing) but in present time it can also pose risk for the environment. One of environmental loads in Slovakia is sludge bed in Slovinky. Village Slovinky is well-known for mining activities during several centuries. From the beginning copper ore was mined there, later on iron ore which was processed in the metallurgical factory in Krompachy. The mining activity in Slovinky was stopped in 1993. Flotation slurry from ore treatment plant was deposited on the sludge bed which was operated from 1968 to 1999. More than 4.8 million cubic meters of slurry is deposited there. Locality of Slovinky is included in State Remediation Program of Environmental Loads (2010-2015). The paper summarizes the actual state of knowledge about environmental impact of mineral processing and theoretical analysis of problem of environmental impact of environmental load – sludge bed in Slovinky. Experimental part of the paper is focused on study of possibilities of elimination of heavy metals in sludge bed material with the aim of improvement of the environmental quality of surveyed locality.
Factors Associated with Hepatitis C Knowledge before and after an Educational Intervention among Vietnamese Americans
Authors: Lee Sunmin , Zhai Shumenghui , Zhang Guo (Yolanda) , Ma Xiang S. , Lu Xiaoxiao , Tan Yin , Siu Philip , Seals Brenda , Ma Grace X.
Published: October 2015

Background

Hepatitis C virus (HCV) is a major cause of chronic liver disease and cancer. Vietnamese Americans are at high risk of HCV infection, with men having the highest US incidence of liver cancer. This study examines an intervention to improve HCV knowledge among Vietnamese Americans.

Study

Seven Vietnamese community-based organizations in Pennsylvania and New Jersey recruited a total of 306 Vietnamese participants from 2010 to 2011.

Results

Average knowledge scores for pretest and posttest were 3.32 and 5.88, respectively (maximum 10). After adjusting for confounding variables, age and higher education were positively associated with higher pretest scores and having a physician who spoke English or Vietnamese was negatively associated with higher pretest scores. Additionally, after adjusting for confounding variables, household income, education, and having an HCV-infected family member significantly increased knowledge scores.

Conclusions

Promotion and development of HCV educational programs can increase HCV knowledge among race and ethnic groups, such as Vietnamese Americans. Giving timely information to at-risk groups provides the opportunity to correct misconceptions, decrease HCV risk behaviors, and encourage testing that might improve timely HCV diagnosis and treatment.
Periodic Breathing in Heart Failure Explained by Dynamic and Static Properties of Respiratory Control
Authors: Miyamoto Tadayoshi , Nakahara Hidehiro , Ueda Shinya , Manabe Kou , Kawai Eriko , Inagaki Masashi , Kawada Toru , Sugimachi Masaru
Published: October 2015

Objective

The respiratory operating point is determined by the interplay between the controller and plant subsystem elements within the respiratory chemoreflex feedback system. This study aimed to establish the methodological basis for quantitative analysis of the open-loop dynamic properties of the human respiratory control system and to apply the results to explore detailed mechanisms of the regulation of respiration and the possible mechanism of periodic breathing in chronic heart failure.

Methods and Results

In healthy volunteers, we measured arterial CO2 partial pressure (PaCO2) and minute ventilation (V̇E) to estimate the dynamic properties of the controller (PaCO2→V̇E relation) and plant (V̇E→PaCO2 relation). The dynamic properties of the controller and plant approximated first- and second-order exponential models, respectively, and were described using parameters including gain, time constant, and lag time. We then used the open-loop transfer functions to simulate the closed-loop respiratory response to an exogenous disturbance, while manipulating the parameter values to deviate from normal values but within physiological ranges. By increasing both the product of gains of the two subsystem elements (total loop gain) and the lag time, the condition of system oscillation (onset of periodic breathing) was satisfied.

Conclusion

When abnormality occurs in a part of the respiratory chemoreflex system, instability of the control system is amplified and may result in the manifestation of respiratory abnormalities such as periodic breathing.
On the Isomorphism Problem for Multiplier Algebras of Nevanlinna-Pick Spaces
Authors: Hartz Michael
Published: October 2015

We continue the investigation of the isomorphism problem for multiplier algebras of reproducing kernel Hilbert spaces with the complete Nevanlinna-Pick property. In contrast to previous work in this area, we do not study these spaces by identifying them with the restrictions of a universal space, namely theDrury-Arveson space. Instead, we work directly with theHilbert spaces and their reproducing kernels. In particular, we show that two multiplier algebras of Nevanlinna-Pick spaces on the same set are equal if and only if the Hilbert spaces are equal. Most of the article is devoted to the study of a special class of complete Nevanlinna-Pick spaces on homogeneous varieties. We provide a complete answer to the question of when two multiplier algebras of spaces of this type are algebraically or isometrically isomorphic.This generalizes results of Davidson, Ramsey,Shalit, and the author.
On the long time behavior of homogeneous Ricci flows
Authors: Böhm Christoph
Published: October 2015

In this paper we prove the following structure results for homogeneous Ricci flow solutions: Any homogeneous Ricci flow solution with finite extinction time develops a Type I singularity. Any homogeneous Ricci flow solution on a compact homogeneous space, not diffeomorphic to a torus, has finite extinction time. Any immortal homogeneous Ricci flow solution develops a Type III singularity and the natural blow downs subconverge to an immortal locally homogeneous Ricci flow solution.
Teichmüller discs with completely degenerate Kontsevich–Zorich spectrum
Authors: Aulicino David
Published: October 2015

We reduce a question of Eskin–Kontsevich–Zorich and Forni–Matheus–Zorich, which asks for a classification of all

{SL}_2(\mathbb{R})

-invariant ergodic probability measures with completely degenerate Kontsevich–Zorich spectrum, to a conjecture of Möller's. Let

\mathcal{D}_g (1)

be the subset of the moduli space of Abelian differentials

\mathcal{M}_g

whose elements have period matrix derivative of rank one. There is an

{SL}_2(\mathbb{R})

-invariant ergodic probability measure

\nu

with completely degenerate Kontsevich–Zorich spectrum, i.e.

\lambda_1 = 1 > \lambda_2 = \cdots = \lambda_g = 0

, if and only if

\nu

has support contained in

\mathcal{D}_g (1)

. We approach this problem by studying Teichmüller discs contained in

\mathcal{D}_g (1)

. We show that if

(X,\omega)

generates a Teichmüller disc in

\mathcal{D}_g (1)

, then

(X,\omega)

is completely periodic. Furthermore, we show that there are no Teichmüller discs in

\mathcal{D}_g (1)

, for

g = 2

, and the two known examples of Teichmüller discs in

\mathcal{D}_g (1)

, for

g = 3, 4

, are the only two such discs in those genera. Finally, we prove that if there are no genus five Veech surfaces generating Teichmüller discs in

\mathcal{D}_5(1)

, then there are no Teichmüller discs in

\mathcal{D}_g (1)

, for

g = 5,6

.
The boundary action of a sofic random subgroup of the free group
Authors: Cannizzo Jan
Published: October 2015

We prove that the boundary action of a sofic random subgroup of a finitely generated free group is conservative (there are no wandering sets). This addresses a question asked by Grigorchuk, Kaimanovich, and Nagnibeda, who studied the boundary actions of individual subgroups of the free group. We also investigate the cogrowth and various limit sets associated to sofic random subgroups. We make heavy use of the correspondence between subgroups and their Schreier graphs, and central to our approach is an investigation of the asymptotic density of a given set inside of large neighborhoods of the root of a sofic random Schreier graph.
The Farrell–Jones conjecture for fundamental groups of graphs of abelian groups
Authors: Gandini Giovanni , Meinert Sebastian , Rüping Henrik
Published: October 2015

We show that the Farrell–Jones conjecture holds for fundamental groups of graphs of groups with abelian vertex groups. As a special case, this shows that the conjecture holds for generalized Baumslag–Solitar groups.
Weak density of orbit equivalence classes of free group actions
Authors: Bowen Lewis
Published: October 2015

It is proven that the orbit-equivalence class of any essentially free probability measure-preserving action of a free group

G

is weakly dense in the space of actions of

G

.
Centralizers of $C^1$-contractions of the half line
Authors: Bonatti Christian , Farinelli Églantine
Published: October 2015

A subgroup

G\subset \operatorname{Diff}^1_+([0,1])

is

C^1

-close to the identity

if there is a sequence

h_n\in \operatorname{Diff}^1_+([0,1])

such that the conjugates

h_n g h_n^{-1}

tend to the identity for the

C^1

-topology, for every

g\in G

. This is equivalent to the fact that

G

can be

embedded in the

C^1

-centralizer

of a

C^1

-contraction of

[0,+\infty)

(see [6] and Theorem 1.1).

We first describe the topological dynamics of groups

C^1

-close to the identity. Then, we show that the class of groups

C^1

-close to the identity is invariant under some natural dynamical and algebraic extensions. As a consequence, we can describe a large class of groups

G\subset \operatorname{Diff}^1_+([0,1])

whose topological dynamics implies that they are

C^1

-close to the identity.

This allows us to show that the free group

\mathbb F_2

admits faithful actions which are

C^1

-close to the identity. In particular, the

C^1

-centralizer of a

C^1

-contraction may contain free groups.
Invariant random subgroups of the free group
Authors: Bowen Lewis
Published: October 2015

Let

G

be a locally compact group. A random closed subgroup with conjugation-invariant law is called an
invariant random subgroup
or IRS for short. We show that each nonabelian free group has a large “zoo” of IRS’s. This contrasts with results of Stuck and Zimmer which show that there are no non-obvious IRS’s of higher rank semisimple Lie groups with property (T).
Flexibility of surface groups in classical simple Lie groups
Authors: Kim Inkang , Pansu Pierre
Published: October 2015

We show that a surface group of high genus contained in a classical simple Lie group can be deformed to become Zariski dense, unless the Lie group is

SU(p,q)

(resp.

SO^* (2n)

,

n

odd) and the surface group is maximal in some

S(U(p,p) \times U(q-p)) \subset SU(p,q)

(resp.

SO^* (2n-2) \times SO(2) \subset SO^* (2n)

). This is a converse, for classical groups, to a rigidity result of S. Bradlow, O. García-Prada and P. Gothen.
Factorization of point configurations, cyclic covers, and conformal blocks
Authors: Bolognesi Michele , Giansiracusa Noah
Published: October 2015

We describe a relation between the invariants of

n

ordered points in projective

d

-space and of points contained in a union of two linear subspaces. This yields an attaching map for GIT quotients parameterizing point configurations in these spaces, and we show that it respects the Segre product of the natural GIT polarizations. Associated to a configuration supported on a rational normal curve is a cyclic cover, and we show that if the branch points are weighted by the GIT linearization and the rational normal curve degenerates, then the admissible covers limit is a cyclic cover with weights as in this attaching map. We find that both GIT polarizations and the Hodge class for families of cyclic covers yield line bundles on

\overline M_{0,n}

with functorial restriction to the boundary. We introduce a notion of divisorial factorization, abstracting an axiom from rational conformal field theory, to encode this property and show that it determines the isomorphism class of these line bundles. Consequently, we obtain a unified, geometric proof of two recent results on conformal block bundles, one by Fedorchuk and one by Gibney and the second author.
Prime numbers along Rudin–Shapiro sequences
Authors: Mauduit Christian , Rivat Joël
Published: October 2015

For a large class of digital functions

f

, we estimate the sums

\sum_{n \leq x} \Lambda(n) f(n)

(and

\sum_{n \leq x} \mu(n) f(n)

, where

\Lambda

denotes the von Mangoldt function (and

\mu

the Möbius function). We deduce from these estimates a Prime Number Theorem (and a Möbius randomness principle) for sequences of integers with digit properties including the Rudin-Shapiro sequence and some of its generalizations.
A presentation by generators and relations of Nichols algebras of diagonal type and convex orders on root systems
Authors: Angiono Iván Ezequiel
Published: October 2015

We obtain a presentation by generators and relations of any Nichols algebra of diagonal type with finite root system. We prove that the defining ideal is finitely generated. The proof is based on Kharchenko’s theory of PBW bases of Lyndon words. We prove that the lexicographic order on Lyndon words is convex for PBW generators and so the PBW basis is orthogonal with respect to the canonical non-degenerate form associated to the Nichols algebra.
Poisson and Hochschild cohomology and the semiclassical limit
Authors: Towers Matthew
Published: October 2015

Let

\mathsf A

be a quantum algebra possessing a semiclassical limit

A

. We show that under certain hypotheses

\mathsf A^e

can be thought of as a deformation of the Poisson enveloping algebra of

A

, and we give a criterion for the Hochschild cohomology of

\mathsf A

to be a deformation of the Poisson cohomology of

A

in the case that

\mathsf A

is Koszul. We verify that condition for the algebra of

2\times 2

quantum matrices and calculate its Hochschild cohomology and the Poisson cohomology of its semiclassical limit.
Linear hyperbolic PDEs with noncommutative time
Authors: Lechner Gandalf , Verch Rainer
Published: October 2015

Motivated by wave or Dirac equations on noncommutative deformations of Minkowski space, linear integro-differential equations of the form

(D+\lambda W)f=0

are studied, where

D

is a normal or prenormal hyperbolic differential operator on

\mathbb R^n

,

\lambda \in \mathbb C

is a coupling constant, and

W

is a regular integral operator with compactly supported kernel. In particular,

W

can be non-local in time, so that a Hamiltonian formulation is not possible. It is shown that for sufficiently small

|\lambda|

, the hyperbolic character of

D

is essentially preserved. Unique advanced/retarded fundamental solutions are constructed by means of a convergent expansion in

\lambda

, and the solution spaces are analyzed. It is shown that the acausal behavior of the solutions is well-controlled, but the Cauchy problem is ill-posed in general. Nonetheless, a scattering operator can be calculated which describes the effect of

W

on the space of solutions to

Df=0

.

It is also described how these structures occur in the context of noncommutative Minkowski space, and how the results obtained here can be used for the analysis of classical and quantum field theories on such spaces.
Mini-Workshop: Einstein Metrics, Ricci Solitons and Ricci Flow under Symmetry Assumptions
Authors: Böhm Christoph , Lauret Jorge , Wang McKenzie
Published: October 2015

Symmetry reduction methods play an important role in the study of Einstein metrics, Ricci solitons and Ricci flow. The general aim of this mini workshop was to gather researchers who have expertise in the construction of geometric examples and to survey and discuss the singularity properties of homogeneous Ricci flows and the existence question for Ricci solitons, in light of the known rigidity results and general properties. Particular topics focused on were the Alekseevskii conjecture for noncompact homogeneous Einstein spaces, the homogeneous Ricci flow and shrinking solitons.
Dirichlet Form Theory and its Applications
Authors: Albeverio Sergio , Chen Zhen-Qing , Fukushima Masatoshi , Röckner Michael
Published: October 2015

Theory of Dirichlet forms is one of the main achievements in modern probability theory. It provides a powerful connection between probabilistic and analytic potential theory. It is also an effective machinery for studying various stochastic models, especially those with non-smooth data, on fractal-like spaces or spaces of infinite dimensions. The Dirichlet form theory has numerous interactions with other areas of mathematics and sciences.

This workshop brought together top experts in Dirichlet form theory and related fields as well as promising young researchers, with the common theme of developing new foundational methods and their applications to specific areas of probability. It provided a unique opportunity for the interaction between the established scholars and young researchers.
Probability, Trees and Algorithms
Authors: Devroye Luc , Neininger Ralph
Published: October 2015

The subject of this workshop were probabilistic aspects of algorithms for fundamental problems such as sorting, searching, selecting of and within data, random permutations, algorithms based on combinatorial trees or search trees, continuous limits of random trees and random graphs as well as random geometric graphs. The deeper understanding of the complexity of such algorithms and of shape characteristics of large discrete structures require probabilistic models and an asymptotic analysis of random discrete structures. The talks of this workshop focused on probabilistic, combinatorial and analytic techniques to study asymptotic properties of large random combinatorial structures.
Mathematics in Undergraduate Study Programs: Challenges for Research and for the Dialogue between Mathematics and Didactics of Mathematics
Authors: Biehler Rolf , Hochmuth Reinhard , Hoyles Dame Celia , Thompson Patrick W.
Published: October 2015

The topic of undergraduate mathematics is of considerable concern for mathematicians in universities, but also for those teaching mathematics as part of undergraduate studies other than mathematics, for employers seeking to employ a mathematically skilled workforce, and for teacher education. Different countries have made and continue to make massive efforts to improve the quality of mathematics education across all age ranges, with most of the research undertaken particularly at the school level. A growing number of mathematicians and mathematics educators now see the need for undertaking interdisciplinary research and collaborative reflections around issues at the tertiary level. The conference aimed to share research results and experiences as a background to establishing a scientific community of mathematicians and mathematics educators whose concern is the theoretical reflection, the research-based empirical investigation, and the exchange of best-practice examples of mathematics education at the tertiary level. The focus of the conference was mathematics education for mathematics, engineering and economy majors and for future mathematics teachers.
Variational Methods for Evolution
Authors: Ambrosio Luigi , Mielke Alexander , Peletier Mark A. , Savaré Giuseppe
Published: October 2015

The workshop brought together researchers from geometry, nonlinear functional analysis, calculus of variations, partial differential equations, and stochastics around a common topic: systems whose evolution is driven by variational principles such as gradient or Hamiltonian systems.

The talks covered a wide range of topics, including variational tools such as incremental minimization approximations, Gamma convergence, and optimal transport, reaction-diffusion systems, singular perturbation and homogenization, rate-independent models for visco-plasticity and fracture, Hamiltonian and hyperbolic systems, stochastic models and new gradient structures for Markov processes or variational large-deviation principles.
Dispersive effects and high frequency behaviour for the Schrödinger equation in star-shaped networks
Authors: Ali Mehmeti Felix , Ammari Kaïs , Nicaise Serge
Published: October 2015

We prove the time decay estimates

L^1 ({\cal R}) \rightarrow L^\infty ({\cal R}),

where

{\cal R}

is an infinite star-shaped network, for the Schrödinger group

e^{it(- \frac{d^2}{dx^2} + V)}

for real-valued potentials

V

satisfying some regularity and decay assumptions. Further we show that the solution for initial conditions with a lower cutoff frequency tends to the free solution, if the cutoff frequency tends to infinity.
Strongly anisotropic elliptic problems with regular and $L^1$ data
Authors: Chrif Moussa , El Manouni Said , Mokhtari Fares
Published: October 2015

In this paper, we obtain the existence of weak solutions to a class of strongly anisotropic nonlinear elliptic boundary-value problems with nonlinear lower-order term with natural growth in an appropriate anisotropic function space. We investigate the cases where the right hand side term is regular or to be in

L^1

. A uniqueness result is also given in a particular case.
A multiparameter family of irreducible representations of the quantum plane and of the quantum Weyl algebra
Authors: Lopes Samuel A. , Lourenço João N.P.
Published: October 2015

We construct a family of irreducible representations of the quantum plane and of the quantum Weyl algebra over an arbitrary field, assuming the deformation parameter is not a root of unity. We determine when two representations in this family are isomorphic, and when they are weight representations, in the sense of [1].
$L^p$ theory for fractional gradient PDE with $VMO$ coefficients
Authors: Schikorra Armin , Shieh Tien-Tsan , Spector Daniel
Published: October 2015

In this paper, we prove

L^p

estimates for the fractional derivatives of solutions to elliptic fractional partial differential equations whose coefficients are

VMO

. In particular, our work extends the optimal regularity known in the second order elliptic setting to a spectrum of fractional order elliptic equations.
Regularity results for non-autonomous variational integrals with discontinuous coefficients
Authors: Passarelli di Napoli Antonia
Published: October 2015

We investigate the regularity propertiesof local minimizers of non autonomous convex integral functionals of the type

\mathcal{F}(u; \Omega):= \int_{\Omega} f (x, Du) \ dx ,

with

p

-growth into the gradient variable and discontinuous dependence on the

x

variable. We prove a higher differentiability result for local minimizers of the functional

\mathcal{F}(u; \Omega)

assuming that the function that measures the oscillation of the integrand with respect to the

x

variable belongs to a suitable Sobolev space.
Fibered spherical 3-orbifolds
Authors: Mecchia Mattia , Seppi Andrea
Published: October 2015

In the early 1930s, Seifert and Threlfall classified up to conjugacy the finite subgroups of SO(4), which gives an algebraic classification of orientable spherical 3-orbifolds. For the most part, spherical 3-orbifolds are Seifert fibered. The underlying topological space and singular set of non-fibered spherical 3-orbifolds were described by Dunbar. In this paper we deal with the fibered case and in particular we give explicit formulae relating the finite subgroups of SO(4) with the invariants of the corresponding fibered 3-orbifolds. This allows us to deduce directly from the algebraic classification topological properties of spherical 3-orbifolds.
Flows driven by rough paths
Authors: Bailleul Ismaël
Published: October 2015

We devise in this work a simple mechanism for constructing flows on a Banach space from approximate flows, and show how it can be used in a simple way to reprove from scratch and extend the main existence and well-posedness results for rough differential equations, in the context of dynamics on a Banach space driven by a Hölder weak geometric rough path; the explosion question under linear growth conditions, Taylor expansion and Euler estimates are also dealt with. We illustrate our approach by proving an existence and well-posedness result for some mean field stochastic rough differential equation.
Gauss words and the topology of map germs from $\mathbb R^3$ to $\mathbb R^3$
Authors: Moya-Pérez Juan Antonio , Nuño Ballesteros Juan José
Published: October 2015

The link of a real analytic map germ

f\colon (\mathbb{R}^{3}, 0) \to (\mathbb{R}^{3}, 0)

is obtained by taking the intersection of the image with a small enough sphere

S^2_\epsilon

centered at the origin in

\mathbb R^3

. If

f

is finitely determined, then the link is a stable map

\gamma

from

S^2

to

S^2

. We define Gauss words which contains all the topological information of the link in the case that the singular set

S(\gamma)

is connected and we prove that in this case they provide us with a complete topological invariant.
Optimal Control of Quasistatic Plasticity with Linear Kinematic Hardening II: Regularization and Differentiability
Authors: Wachsmuth Gerd
Published: October 2015

We consider an optimal control problem governed by an evolution variational inequality arising in quasistatic plasticity with linear kinematic hardening. A regularization of the time-discrete problem is derived. The regularized forward problem can be interpreted as system of coupled quasilinear PDEs whose principal parts depend on the gradient of the state. We show the Fréchet differentiability of the solution map of this quasilinear system. As a consequence, we obtain a first order necessary optimality system. Moreover, we address certain convergence properties of the regularization.
Positive Solutions for Nonlinear Nonhomogeneous Robin Problems
Authors: Gasiński Leszek , O'Regan Donal , Papageorgiou Nikolaos S.
Published: October 2015

We consider a nonlinear, nonhomogeneous Robin problem with a Carathéodory reaction which satisfies certain general growth conditions near

0^+

and near

+ \infty

. We show the existence and regularity of positive solutions, the existence of a smallest positive solution and under an additional condition on the reaction, we show the uniqueness of the positive solutions. We then show that our setting incorporates certain parametric Robin equations of interest such as nonlinear equidiffusive logistic equations.
Uniform Exponential Stability of Discrete Semigroup and Space of Asymptotically Almost Periodic Sequences
Authors: Ahmad Nisar , Khalid Habiba , Zada Akbar
Published: October 2015

We prove that the discrete semigroup

\mathbb{T}= \{\mathcal{T}(n): n \in \mathbb{Z_+}\}

is uniformly exponentially stable if and only if for each

z(n)\in \mathbb{AAP}_0(\mathbb{Z}_+,\mathcal{X})

the solution of the Cauchy problem

\left\{
\begin{aligned}
y_{n+1} &= \mathcal{T}(1)y_{n}+ z(n+1), \\
y(0)&= 0
\end{aligned} \right.

belongs to

\mathbb{AAP}_0(\mathbb{Z}_+,\mathcal{X})

. Where

\mathcal{T}(1)

is the algebraic generator of

\mathbb{T}

,

\mathbb{Z}_+

is the set of all non-negative integers and

\mathcal{X}

is a complex Banach space. Our proof uses the approach of discrete evolution semigroups.
Angle Preserving Mappings
Authors: Zamani Ali , Moslehian Mohammad Sal , Frank Michael
Published: October 2015

In this paper, we give some characterizations of orthogonality preserving mappings between inner product spaces. Furthermore, we study the linear mappings that preserve some angles. One of our main results states that if

\mathcal{X}, \mathcal{Y}

are real inner product spaces and

\theta\in(0, \pi)

, then an injective nonzero linear mapping

T:\mathcal{X}\longrightarrow \mathcal{Y}

is a similarity whenever (i)

x\underset{\theta}{\angle} y\, \Leftrightarrow \,Tx\underset{\theta}{\angle} Ty

for all

x, y\in \mathcal{X}

; (ii) for all

x, y\in \mathcal{X}

,

\|x\|=\|y\|

and

x\underset{\theta}{\angle} y

ensure that

\|Tx\|=\|Ty\|

. We also investigate orthogonality preserving mappings in the setting of inner product

C^{*}

-modules. Another result shows that if

\mathbb{K}(\mathscr{H})\subseteq\mathscr{A}\subseteq\mathbb{B}(\mathscr{H})

is a

C^{*}

-algebra and

T\,:\mathscr{E}\longrightarrow \mathscr{F}

is an

\mathscr{A}

-linear mapping between inner product

\mathscr{A}

-modules, then

T

is orthogonality preserving if and only if

|x|\leq|y|\, \Rightarrow \,|Tx|\leq|Ty|

for all

x, y\in \mathscr{E}

.
Audiencias en revolución, usos y consumos de las aplicaciones de los medios de comunicación en tabletas y teléfonos inteligentes
Authors: Ortega Mohedano Félix , González Ispierto Beatriz , Pérez Peláez María Esther
Published: October 2015

Presentamos en este artículo los resultados de una investigación realizada en la Universidad de Salamanca desde el Observatorio de Contenidos Audiovisuales en el año 2014. El objetivo de este estudio es el de analizar los usos y consumos de aplicaciones de los medios de comunicación entre los estudiantes de la Universidad de Salamanca. La investigación realizó entrevistas cara a cara a alumnos de la Universidad de Salamanca seleccionados aleatoriamente mediante la utilización de un cuestionario C-TAPI, Computer or Tablet Assisted Personal Interview. Presentamos un contraste de las hipótesis de investigación, resultados y conclusiones que nos permiten describir los usos y consumos de los estudiantes de la Universidad de Salamanca en su interacción con las aplicaciones de los medios de comunicación. Analizamos la asignación del tiempo y espacios de consumo a la hora de utilizar tabletas y teléfonos inteligentes. Este trabajo nos permite identificar las tendencias más significativas que se consolidan entre los usuarios más jóvenes. Los medios de comunicación se están adaptando progresivamente a la migración que la audiencia está realizando hacia renovados modos y usos del dónde, cuándo y cómo desea consumir contenidos audiovisuales. Gracias a las nuevas pantallas inteligentes los usuarios pueden consumir televisión-vídeo desde cualquier dispositivo que tenga acceso a la red. Los grupos de comunicación están adaptando la tradicional cadena de valor del audiovisual, de la televisión, de la radio y de la prensa a las nuevas demandas de una audiencia joven multipantalla e hiper-conectada que se encuentra cada vez más vinculada en su ocio y consumo con dispositivos cada vez más interactivos e inteligentes.