Downward Flame Spread Rate Over PMMA Rods Under External Radiant Heating

Fire Technology - There are multiple situations in which fires may occur at environmental conditions that are different than standard atmospheric conditions. Changes in ambient pressure, oxygen...     

Thermal Expansion of Alkaline‐Doped Lanthanum Ferrite Near the Néel Temperature

The thermal expansion and magnetic behaviors of divalent, alkaline‐doped lanthanum ferrites (La_0.9M_0.1FeO₃, M=Ca, Sr, Ba) were assessed using a combination of dilatometry, magnetometry, time‐of‐flight neutron diffraction, and high‐temperature X‐ray diffraction. Néel temperatures were determined through vibrating sample magnetometry and correlated well with changes in thermal expansion behavior observed during both dilatometry and X‐ray diffraction. The Néel temperatures observed for pure, Ca‐doped, Sr‐doped, and Ba‐doped lanthanum ferrites were 471°C, 351°C, 465°C, and 466°C, respectively. The effect of divalent substitutions on the magnetic behavior are attributed to charge compensation mechanisms and structural changes in the material.     

Experience from the post-test analysis of MEGAPIE

The (MEGAWatt Pilot Experiment) MEGAPIE target was successfully irradiated in 2006 at the SINQ facility of the Paul Scherrer Institut. During the irradiation a series of measurements to monitor the operation of the target, the thermal hydraulics behavior and the neutronic and nuclear aspects, has been performed. In the post-test analysis phase of the project, the data were analyzed and important information relevant to accelerator-driven systems (ADS) was gained, in particular: (i) from the operation of the target several recommendations concern the simplification of the system and the improved reliability; (ii) data from the thermal hydraulic measurements have offered the opportunity to validate the codes used in the design phase; (iii) the neutronic analysis confirm the high performance of a liquid metal target and the importance of the delayed neutron measurements in an ADS target; (iv) the nuclear measurements of the gas released gave the opportunity to validate the codes used during the design phase and provided indications for the operation. From the results in these different domains recommendations to further development of ADS and heavy liquid metal targets are discussed.     

不同脱毒方法对玉米秸秆水解液酒精发酵的影响

利用湿热预处理(195℃,15 min)后的玉米秸秆水解液,考察了3种不同脱毒方法(中和法、饱和生石灰法和Na2SO3法)对水解液中的抑制剂的去除效果,研究了树干毕赤酵母(Pichia stipitis 58376)对脱毒后的水解液酒精发酵情况.结果表明:玉米秸秆水解液经过3种方法脱毒处理后,醛类抑制荆(糠醛和5-羟甲...     

On the Relation between Morphology and FET Mobility of Poly(3‐alkylthiophene)s at the Polymer/SiO2 and Polymer/Air Interface

The influence of the interface of the dielectric SiO₂ on the performance of bottom‐contact, bottom‐gate poly(3‐alkylthiophene) (P3AT) field‐effect transistors (FETs) is investigated. In particular, the operation of transistors where the active polythiophene layer is directly spin‐coated from chlorobenzene (CB) onto the bare SiO₂ dielectric is compared to those where the active layer is first spin‐coated then laminated via a wet transfer process such that the film/air interface of this film contacts the SiO₂ surface. While an apparent alkyl side‐chain length dependent mobility is observed for films directly spin‐coated onto the SiO₂ dielectric (with mobilities of ≈10^?3 cm² V^?1 s^?1 or less) for laminated films mobilities of 0.14 ± 0.03 cm² V^?1 s^?1 independent of alkyl chain length are recorded. Surface‐sensitive near edge X‐ray absorption fine structure (NEXAFS) spectroscopy measurements indicate a strong out‐of‐plane orientation of the polymer backbone at the original air/film interface while much lower average tilt angles of the polymer backbone are observed at the SiO₂/film interface. A comparison with NEXAFS on crystalline P3AT nanofibers, as well as molecular mechanics and electronic structure calculations on ideal P3AT crystals suggest a close to crystalline polymer organization at the P3AT/air interface of films from CB. These results emphasize the negative influence of wrongly oriented polymer on charge carrier mobility and highlight the potential of the polymer/air interface in achieving excellent “out‐of‐plane” orientation and high FET mobilities.     

On the free vibration of sandwich panels with a transversely flexible and temperature-dependent core material – Part I: Mathematical formulation

The free vibration analysis of sandwich panels with a core that is flexible and compliant in the vertical direction and with temperature-dependent mechanical properties is presented in two parts. The first part presents the mathematical formulation while the second deals numerically with the effects of the degrading properties of the core on the free vibration response. The analysis is based on the high-order sandwich panel theory approach (HSAPT), and the equations of motions along with the appropriate boundary conditions are derived using the Hamilton’s principle. The study investigates the role of increasing temperature, through the degradation of the mechanical properties of the core, on the free vibration response of structural sandwich panels. The mathematical formulation uses two types of computational models. At first, following the HSAPT approach, the unknowns include the displacements of the face sheets as well as the shear stress in the core. Secondly, it is assumed that the through-thickness distributions of the vertical and horizontal core displacements can be represented as polynomials, following the results of the HSAPT static case, and the effect of the variable mechanical properties are implemented directly.     

In vivo validation of a blood vector velocity estimator with MR angiography

Conventional Doppler methods for blood velocity estimation only estimate the velocity component along the ultrasound beam direction. This implies that a Doppler angle under examination close to 90° results in unreliable information about the true blood direction and blood velocity. The novel method transverse oscillation (TO), which combines estimates of the axial and the transverse velocity components in the scan plane, makes it possible to estimate the vector velocity of the blood regardless of the Doppler angle. The present study evaluates the TO method with magnetic resonance phase contrast angiography (MRA) by comparing in vivo measurements of stroke volume. Eleven healthy volunteers were included in this prospective study. From the obtained data sets recorded with the 2 modalities, vector velocity sequences were constructed and stroke volume calculated. Angle of insonation was approximately 90° for TO measurements. The correlation between the stroke volume estimated by TO and MRA was 0.91 (p < 0.01) with the equation for the line of regression: MRA = 1.1?TO-0.4. A Bland-Altman plot was additionally constructed where the mean difference was 0.2 ml with limits of agreement at ?1.4 ml and 1.9 ml. The results indicate that reliable vector velocity estimates can be obtained in vivo using the presented angle-independent 2-D vector velocity method. The TO method can be a useful alternative to conventional Doppler systems by avoiding the angle artifact, thus giving quantitative velocity information.     

Cryptanalysis of MD2

This paper considers the hash function MD2 which was developed by Ron Rivest in 1989. Despite its age, MD2 has withstood cryptanalytic attacks until recently. This paper contains the state-of-the-art cryptanalytic results on MD2, in particular collision and preimage attacks on the full hash function, the latter having complexity 2⁷³, which should be compared to a brute-force attack of complexity 2¹²⁸.     

How to get residents/owners in housing cooperatives to agree on sustainable renovation

What factors increase the chance that residents/owners in housing cooperatives agree on sustainable energy efficient renovation? Based on 30 qualitative interviews with professional advisors in cooperative housing associations and chairman/board and residents in three chosen case studies, an analysis of opportunities and barriers for making a common decision on renovation is performed. Success criteria and barriers are found on the societal level as well as on the organizational/individual level. The barriers and success criteria identified on the societal level are: knowledge level on energy-efficient renovation among relevant actors, owner structure of the housing cooperative, and existing regulations and incentives. On the organizational and individual level, the following categories influencing renovation processes were identified: the time frame and organization of the process, understanding the residents` needs, economy, the information given, and the existence of available exemplary projects and role models. Based on the results of the study, ten guidelines that contribute to more successful decision making processes and increase the chances of sustainable energy efficient renovation in housing cooperatives are presented.