Beitrag zur Erfassung einiger rheologischer Eigenschaften von Weizenkleber

Contribution to Assessment of some Rheological Properties of Wheat Gluten. The production of wheat gluten has increased considerably in the recent times and producers of vital gluten are searching for new markets and applications. Its main functional properties can be characterised by means of rheometry. Some possibilities offered by the empirical and basic rheometry in recording the viscosity and elasticity of rehydrated vital gluten and of vital and modified gluten dispersed in different solvents, are shown. Both, the properties of gluten and the ability of solvents in modifying the gluten, can be monitored. A standardised preparation of test samples and of carrying out the measurements is required for obtaining reliable measuring data.     

An LIF characterization of supersonic BO (X2Σ+) and CN (X2Σ+) radical sources for crossed beam studies

Various ablation sources generating supersonic boron monoxide (BO; X(2)Σ(+)) radical beams utilizing oxygen (O(2)), carbon dioxide (CO(2)), methanol (CH(3)OH), and water (H(2)O) as seeding gases were characterized in a crossed molecular beams setup by mass resolved time-of-flight spectroscopy and spectroscopically via laser induced fluorescence. Intensities of the sources as well as rovibrational energy distributions were analyzed. The molecular oxygen source was found to produce excessive amount of an unwanted BO(2) byproduct. Internal vibrational energy of boron monoxide generated in the water and methanol sources was too high to be considered for the study of dynamics of ground state radicals. The best combination of intensity, purity, and low internal energy was found in the carbon dioxide source to generate boron monoxide. We successfully tested the boron monoxide (BO; X(2)Σ(+)) radical beam source in crossed beams reactions with acetylene (C(2)H(2)) and ethylene (C(2)H(4)). The source was also compared with supersonic beams of the isoelectronic cyano (CN; X(2)Σ(+)) radical.     

“Solving” ambiguity in the virtual space: communication strategies in a collaborative virtual environment

Collaborative virtual environments (CVE) face the challenge of succeeding in incorporating critical dimensions of cooperation and communication in everyday working situations. One of these dimensions, situation ambiguity, is scarcely considered in studies on CVE although it can prove a key factor in future use of CVE in real work situations. Many computer-supported cooperative environments and telecommunication systems, like those currently used in telemedicine, would benefit from the incorporation of some degree of situation ambiguity allowing users to deploy their diagnostic and interpretive abilities. In the perspective adopted in this study, ambiguity is the contingent outcome of the ongoing interaction taking place between the environment and the interests of social actors. The research focuses on the cooperation within couples of participants facing situation ambiguity in a virtual environment: a simulated city named Babylon. Participants moved in the city through an avatar and could communicate in one of the following conditions: face-to-face, phone or chat. Their goal was that of meeting somewhere in the city, in a place that they did not know previously. Babylon contained elements designed to allow both production and detection of ambiguity. Ambiguity emerged when participants realized the presence of inconsistencies in the way they perceived the situations they had to face. The moments in which ambiguity was perceived—called “critical events” (CE)—were measured and described through qualitative (ethnographically oriented) methods. The different strategies that participants used to “solve” ambiguity were characterized as: looking for environmental cues, narrowing the focus of attention and investing on cooperation. Both CEs and strategies were analyzed with respect to the three communication conditions: face-to-face, phone and chat. All the communication conditions allowed the emergence of ambiguity and the negotiation of strategies to solve ambiguity between partners: according to literature, chat is very costly in terms of time spent on writing but this disadvantage did not block completely the emergence of ambiguity and the development of adequate strategies of solution. All navigations but three (on a total of 18 couples) succeeded: the partners did meet in a short time (less than 15 min) relying on their pragmatic resources in a new virtual place. Further research is required to clarify the possible factors influencing the choice of one strategy over the others, the order in which strategies follow each other and the role of leadership in ambiguity detection and solution.     

P2P storage systems: Study of different placement policies

In a P2P storage system using erasure codes, a data block is encoded in many redundancy fragments. These fragments are then sent to distinct peers of the network. In this work, we study the impact of different placement policies of these fragments on the performance of storage systems. Several practical factors (easier control, software reuse, latency) tend to favor data placement strategies that preserve some degree of locality. We compare three policies: two of them are local, in which the data are stored in logical neighbors, and the other one, global, in which the data are spread randomly in the whole system. We focus on the study of the probability to lose a data block and the bandwidth consumption to maintain such redundancy. We use simulations to show that, without resource constraints, the average values are the same no matter which placement policy is used. However, the variations in the use of bandwidth are much more bursty under the local policies. When the bandwidth is limited, these bursty variations induce longer maintenance time and henceforth a higher risk of data loss. We then show that a suitable degree of locality could be introduced in order to combine the efficiency of the global policy with the practical advantages of a local placement. Additionally, we propose a new external reconstruction strategy that greatly improves the performance of local placement strategies. Finally, we give analytical methods to estimate the mean time to the occurrence of data loss for the three policies.     

Earth Observation application development based on the Grid oriented ESIP satellite image processing platform

Satellite images supply important information on earth surface, weather, clime, geographic areas, vegetation, and natural phenomena. Processing of satellite data requires high computation resources and flexible tools in order to search, discover, and reveal the main information, to experiment new algorithms, and to include them into new Earth Observation applications. This paper describes the features and the architectures of the ESIP and gProcess platforms, supporting the Grid based satellite imagery processing. The development methodology of Earth Observation applications is highlighted as well in order to hide the Grid complexity to the user.     

Cellular mechanism underlying the efficacy of the sotalol-quinidine combination

The combination of quinidine and sotalol is very effective in prevention of recurrent sustained ventricular tachycardia (SVT). The cellular mechanisms underlying this efficacy were examined in guinea pig papillary muscle, using standard microelectrode techniques and stimulation frequencies of 1, 2, and 3 Hz. Action potential duration (APD) and effective refractory period (ERP) were measured under control conditions, after 30-min perfusion with quinidine (5 microM) or sotalol (6 microM), and after an additional 30 min of quinidine + sotalol (5 and 6 microM, respectively). Quinidine, sotalol, and quinidine + sotalol all prolonged APD at 90% repolarization (APD90) by 9 +/- 1, 13 +/- 1, and 15 +/- 2%, respectively (at 3 Hz; p = NS, comparison of the three drugs; p < 0.05 for each drug as compared with control). Quinidine + sotalol prolonged ERP (at 3 Hz) by 27 +/- 2% as compared with 11 +/- 2% after sotalol and 18 +/- 2% after quinidine alone (p < 0.05). As a result, the ERP/APD ratio was increased by the combination to 0.87 +/- 0.2 (p < 0.05) as compared with 0.78 +/- 0.2 for control 0.79 +/- 0.1 for sotalol, and 82 +/- 0.1 for quinidine (at 3 Hz). Although sotalol alone decreased the maximum rate of depolarization of phase 0 of the AP (Vmax) by only 3 +/- 2% (p = NS), sotalol attenuated Vmax decrease of quinidine (at 3 Hz) from 40 +/- 4 to 16 +/- 3% (p < 0.05). Effects at 1 and 2 Hz were similar.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experimental and numerical determination of mechanical properties of polygonal wood particles and their flow analysis in silos

Responding to a lack in the literature, mechanical properties of polygonal wood particles are determined for use in a discrete element model (DEM) for flow analysis in silos, and some methods are proposed for determining such parameters. The parameters arrived at here have also formed part of the input to the SPOLY software, developed in-house to compute the DEM model with spheropolyhedron elements. The model is validated using a 2D physical model, where “prismatic” particles with polygonal cross sections are placed inside a silo with variable aperture and hopper angle. Validation includes comparison of flow-rates computed by SPOLY, displacement profiles, and clogging thresholds with experimental results. The good agreement that emerges will encourage future use of miniature triaxial tests, grain-surface profilometry, inclined slope tests, and numerical analysis of the intragranular stresses—toward a direct construction of the contact-deformation relations required in realistic DEM modelling of particle flow with angular-shaped particles.     

Improved Method for Creating Time-Domain Unsteady Aerodynamic Models

Multidisciplinary aeroservoelastic interactions are studied by the combination of knowledge acquired in two main disciplines: aeroelasticity and servocontrols. In aeroelasticity, the doublet lattice method is used to calculate the unsteady aerodynamic forces for a range of reduced frequencies and Mach numbers on a business aircraft in the subsonic flight regime by use of NASTRAN software. For aeroservoelasticity studies, there is the need to conceive methods for these unsteady aerodynamic forces conversions from frequency into Laplace domain. A new method different from classical methods is presented, in which Chebyshev polynomials theories and their orthogonality properties are applied. In this paper, a comparison between flutter results expressed in terms of flutter speeds and frequencies obtained with our method with flutter results obtained with classical Padé and least squares methods is presented for a business aircraft at one Mach number and a range of reduced frequencies. It has been found that results obtained with our method are better in terms of average error than results obtained with the two classical methods here presented.