Melting of polymer blends in single-screw extrusion : an experimental study

Melting is a major step in plasticating single screw extrusion, but most of the existing phenomenological know how was gathered by performing Maddock-type experiments with homopolymers. Given the current widespread industrial use of polymer blends, it is worth determining whether the same mechanisms and mathematical models apply, or whether different sequences develop. This work reports the results of Maddock-type experiments using a PA6/PP blend, both in its immiscible and compatibilized varieties. A melting mechanism combining the features of the classical Tadmor mechanism and of the dispersed melting mechanism, also previously reported in the literature, was observed.The authors are grateful to Portuguese Fundacao para a Ciencia e Tecnologia for supporting this work under grant SFRH/BD/19997/2004 and to DSM, the Netherlands, for supplying PA6

Cinema-going trajectories in the digital age

The activity of cinema-going constantly evolves and gradually integrates the use of digital data and platforms to become more engaging for the audiences. Combining methods from the fields of Human Computer Interaction and Film Studies, we conducted two workshops seeking to understand cinema audiences’ digital practices and explore how the contemporary cinema-going experience is shaped in the digital age. Our findings suggest that going to the movies constitutes a trajectory during which cinemagoers interact with multiple digital platforms. At the same time, depending on their choices, they construct unique digital identities that represent a set of online behaviours and rituals that cinemagoers adopt before, while and after cinema-going. To inform the design of new, engaging cinemagoing experiences, this research establishes a preliminary map of contemporary cinema-going including digital data and platforms. We then discuss how audiences perceive the potential improvement of the experience and how that would lead to the construction of digital identities

Meetmethoden weerbaarheid

As a result of increased interdependencies between systems and infrastructures, society has become more complex over the last decades. This has resulted in an intrinsically enlarged vulnerability with respect to disruptions and a larger uncertainty about its nature and consequences. This is an explorative study with as main research question: which set of indicators can be used to determine the resilience level of the Dutch society and in which ways can these indicators be measured and condensed in an effective and justified manner?De maatschappij is vanwege de onderlinge verbondenheid en afhankelijkheid van systemen en infrastructuren de afgelopen decennia aanzienlijk complexer geworden. Dit heeft geleid tot een intrinsiek toegenomen kwetsbaarheid voor verstoringen en tot een grotere onzekerheid omtrent de aard en gevolgen ervan. Dit is een inventariserend onderzoek met als hoofdvraag: met welke set van indicatoren kan het weerbaarheidsniveau van de Nederlandse samenleving worden vastgesteld en op welke manieren kunnen deze indicatoren op een efficiënte en verantwoorde wijze gemeten en samengevat worden? INHOUD: 1. Inleiding 2. Een systeem-dynamische benadering van weerbaarheid 3. Overwegingen bij het meten van weerbaarheid 4. Het systeem ‘weerbaarheid van de samenleving’ in termen van kapitalen en voorraden 5. Inventarisatie en selectie voor modellering 6. Inventarisatie en selectie van meetmethoden 7. Externe validatie 8. Aanbevelingen voor het opzetten van een weerbaarheidsmonitor 9. Referentie

Numerical modeling of CLT diaphragms tested on a shake-table experiment

Current standards and existing literature provide very limited information regarding the design of cross-laminated timber (CLT) floor diaphragms. In addition, limited procedures exist to develop analytical models to estimate the deformation response of CLT floor diaphragms. This paper presents a modelling approach that captures the response of CLT timber diaphragms, with a special focus on CLT spline panel-to-panel connections. The modeling approach is validated through the comparison of the results of the computation model with experimental data obtained from a series of shake-tables test performed on a two-story full-scale building tested in the summer of 2017 at UC San Diego Large High Performance Outdoor Shake Table. The two-story building included two diaphragm designs at each floor level. The first solution consists of CLT panels connected with plywood surface splines that are fastened using self-tapping screws, while the second consists of a CLT-concrete composite floor solution. Results from the nonlinear pushover analysis describe accurately the experimental data obtained.(undefined

Analytical and Numerical Models for Wind and Seismic Design and Assessment of Mass Timber Diaphragms

While the use of cross-laminated timber (CLT) panels for building construction has increased over the last several decades, current standards and existing literature provide limited information regarding the design of CLT diaphragms or the prediction of their deflections when subjected to wind and strong earthquake motions. This paper presents the design and assessment of a CLT diaphragm that was part of a full-scale two-story structure subjected to shake-table testing. An analytical model is proposed for diaphragm deflection accounting for in-plane shear and bending stiffness, as well as the stiffness of various connections. Moreover, a refined numerical modeling strategy is proposed in order to consider phenomena such as panel-to-panel gap closure. Results indicate that the analytical model yields conservative results both in terms of deflections and forces when compared to the numerical model that simulates similar sources of strength and stiffness. The analytical model is suitable for the design of symmetric diaphragms with regular shapes, whereas the numerical model can also be used to model asymmetric diaphragms with irregular shapes

Seismic assessment of a heavy-timber frame structure with ring-doweled moment-resisting connections

The performance of heavy-timber structures in earthquakes depends strongly on the inelastic behavior of the mechanical connections. Nevertheless, the nonlinear behavior of timber structures is only considered in the design phase indirectly through the use of an R-factor or a q-factor, which reduces the seismic elastic response spectrum. To improve the estimation of this, the seismic performance of a three-story building designed with ring-doweled moment resisting connections is analyzed here. Connections and members were designed to fulfill the seismic detailing requirements present in Eurocode 5 and Eurocode 8 for high ductility class structures. The performance of the structure is evaluated through a probabilistic approach, which accounts for uncertainties in mechanical properties of members and connections. Nonlinear static analyses and multi-record incremental dynamic analyses were performed to characterize the q-factor and develop fragility curves for different damage levels. The results indicate that the detailing requirements of Eurocode 5 and Eurocode 8 are sufficient to achieve the required performance, even though they also indicate that these requirements may be optimized to achieve more cost-effective connections and members. From the obtained fragility curves, it was verified that neglecting modeling uncertainties may lead to overestimation of the collapse capacity

Thermal magnetic resonance: physics considerations and electromagnetic field simulations up to 23.5 Tesla (1GHz)

BACKGROUND: Glioblastoma multiforme is the most common and most aggressive malign brain tumor. The 5-year survival rate after tumor resection and adjuvant chemoradiation is only 10 %, with almost all recurrences occurring in the initially treated site. Attempts to improve local control using a higher radiation dose were not successful so that alternative additive treatments are urgently needed. Given the strong rationale for hyperthermia as part of a multimodal treatment for patients with glioblastoma, non-invasive radio frequency (RF) hyperthermia might significantly improve treatment results. METHODS: A non-invasive applicator was constructed utilizing the magnetic resonance (MR) spin excitation frequency for controlled RF hyperthermia and MR imaging in an integrated system, which we refer to as thermal MR. Applicator designs at RF frequencies 300 MHz, 500 MHz and 1GHz were investigated and examined for absolute applicable thermal dose and temperature hotspot size. Electromagnetic field (EMF) and temperature simulations were performed in human voxel models. RF heating experiments were conducted at 300 MHz and 500 MHz to characterize the applicator performance and validate the simulations. RESULTS: The feasibility of thermal MR was demonstrated at 7.0 T. The temperature could be increased by ~11 °C in 3 min in the center of a head sized phantom. Modification of the RF phases allowed steering of a temperature hotspot to a deliberately selected location. RF heating was monitored using the integrated system for MR thermometry and high spatial resolution MRI. EMF and thermal simulations demonstrated that local RF hyperthermia using the integrated system is feasible to reach a maximum temperature in the center of the human brain of 46.8 °C after 3 min of RF heating while surface temperatures stayed below 41 °C. Using higher RF frequencies reduces the size of the temperature hotspot significantly. CONCLUSION: The opportunities and capabilities of thermal magnetic resonance for RF hyperthermia interventions of intracranial lesions are intriguing. Employing such systems as an alternative additive treatment for glioblastoma multiforme might be able to improve local control by “fighting fire with fire”. Interventions are not limited to the human brain and might include temperature driven targeted drug and MR contrast agent delivery and help to understand temperature dependent bio- and physiological processes in-vivo