Alleviating a form of electric vehicle range anxiety through On-Demand vehicle access

On-demand vehicle access is a method that can be used to reduce types of range anxiety problems related to planned travel for electric vehicle owners. Using ideas from elementary queueing theory, basic QoS metrics are defined to dimension a shared fleet to ensure high levels of vehicle access. Using mobility data from Ireland, it is argued that the potential cost of such a system is very low

Horizontal secondary gas injection in fluidized beds: Solids concentration and velocity in multiphase jets

Secondary gas injection into fluidized beds is used in many industrial applications to control the particle size (1) or to introduce a reactant gas (2). Also in fluidized bed opposed jet mills a highly expanded gas can be used to grind particles into the submicron range. To model and improve processes which use secondary gas injection, a better understanding of the multiphase flow inside the jets is indispensable. A contribution to this is the analysis of the particle velocity via particle image velocimetry (PIV). These experiments were carried out in a semicircle fluidized bed with optical access, so that the morphology, particle acceleration and entrainment behavior can be visualized. These results can be compared to a simple model for the calculation of particle velocities in free jets and give a good agreement. Additionally, the solids concentrations in the particle laden gas jets are investigated with capacitance probes, an invasive measurement technique (3). Thus a solid concentration profile of the jet area can be determined and together with the PIV-data the solid mass flow can be estimated. This information is important for the calculation of the residence time in a reaction zone or the load condition in a jet mill. Parameters for those studies were the particle-size-distributions, the nozzle diameter, secondary gas velocity or the fluidization velocity. The measurements as well as the comparisons with calculations and models have discovered some unexpected insights in the multiphase flow of gas jets into fluidized beds and in the comminution process in fluidized bed opposed jet mills. REFERENCES J. McMillan, C. Briens, F.Berruti, and E.Chan. High velocity attrition nozzles in fluidized beds. Powd. Techn., 175:133-141, 2007. L. Chen, and H. Weinstein. Shape and extent of the void formed by a horizontal jet in a fluidized bed. AIChE. Journ., 39(12):1901-1909, 1993. M. Richtberg, R. Richter, and K.-E. Wirth. Characterization of the flow patterns in a pressurized circulating fluidized bed. Powd. Techn., 155:145-152, 2005

Prediction of the radial solids concentration distribution in circulating fluidized bed risers

The presented work deals with the development of a model for the prediction of the radial solids concentration distribution in circulating fluidized bed risers. In order to provide a substantial basis for the model development, non‑invasive investigations on the solids distribution over the cross-section of a pilot plant scale circulating fluidized bed riser are carried out using X‑ray computed tomography. The examined operating range covers cross-section averaged solids concentrations between 2.7 vol.% and 38.1 vol.% while superficial gas velocities were adjusted in the range from 0.4 m s‑1 up to 6.0 m s‑1. Especially in the case of dense gas‑solid flow conditions detrimental beam hardening effects gain influence, distorting the results of the X-ray measurements (1). Thus, a novel calibration method is presented to facilitate the derivation of volumetric solids concentrations from the measured tomographic attenuation data. In this, an emphasized feature consists in the elimination of low energetic radiation from the incident X‑ray spectrum to avoid beam hardening effects, which are caused by the pipe material and the fluidized solids. Evaluation of the presented technique by comparison of the derived cross-section averaged solids concentrations with those obtained from differential pressure measurements confirms its high accuracy. Subsequently, the technique is applied for quantitative analysis of the radial solids concentration distribution in a gas‑solid circulating fluidized bed riser in dependence of the overall solids holdup and the superficial gas velocity. The high spatial resolution and the non-invasive character of the applied technique allow for detailed examination of the solids concentration prevailing in close proximity of the inner riser wall as well as in the center of the cross-section. The tomographic X‑ray scans of the cross-section of the riser, operated under dilute and highly dense conditions, provide a comprehensive set of measurement data, based on which a model is developed that allows for the prediction of the radial solids concentration distribution in vertical gas-solid upflow. The proposed model is found to reliably predict the radial solids concentration distribution under dilute as well as under dense flow conditions. Please click Additional Files below to see the full abstract

Treatment of polymer powders by combining an atmospheric plasma jet and a fluidized bed reactor

Recently additive manufacturing processes such as laser beam melting (LBM) of polymers have gained more importance for industrial applications (1). Tailor-made modification of polymers is essential to make these processes more efficient and to cover a wider range of industrial applications. The so far used polymer materials show weak performance regarding the mechanical stability of processed parts being mainly due to poor linkage between LBM powder particles. To overcome this, a new route to functionalize the surface of commercially available polymer particles using an atmospheric plasma jet has been investigated. The process of plasma-functionalization using different gas mixtures allows introducing reactive groups onto the particle surface. Consequently, an improvement of adhesion and wettability of the polymer surface (2), (3) without restraining the bulk properties of the powder is achieved. The experiments are conducted in a fluidized bed reactor (FBR) with a diameter of 0.1 m while the plasma jet is located in the center of the distribution plate at the bottom of the FBR. Since fluidized bed reactors are characterized by excellent heat and mass transfer, a homogenous distribution of generated process heat and the induced reactive species can be achieved. The main influencing parameter is the behavior of the dense plasma jet within the fluidized particles. The resulting contact time of single particles with reactive species formed is a key parameter for the functionalization process. Results for the spread of the jet as well as the effect of the functionalization as a function of treatment time will be shown. Please click Additional Files below to see the full abstract

Characteristics of a semi-industrial downer reactor for the rounding of irregular polymer particles

In the past additive manufacturing processes such as laser beam melting (LBM) were almost exclusively applied for the generation of prototypes. In recent years, however, these methods have gradually been transferred to serial production (1). With this grown relevance on industrial applications, the demands on the powder material have increased as well. In consequence, there is a need for fine powders of different polymers showing good powder flowability and high bulk density (2) It has been shown that different polymers can be ground down to the micron size range by a wet grinding process (2). Due to the grinding process the produced particles are in a chiseled state, which leads to a bad flowability. To solve this problem the single particles are melted in a heated downer reactor and spherical particles are obtained by using the effect of the surface tension (3). The rounding process was performed in a reactor with a length of 6 m and a diameter of 0.1 m. The main focus of this work is to describe the flow characteristics of both, gas and particles in the reactor. Other influencing parameters on the outcome of the rounding such as particle load and temperature distribution will also be addressed. One major critical point, the influence of the particle and gas inlet on the flow pattern will be discussed in detail. The mechanism of the rounding process in dependence of particle size, interfacial tension and melt viscosity will be shown within a sintering model (4). Please click Additional Files below to see the full abstract

Use of computed tomography and mechanical CPR in cardiac arrest to confirm pulmonary embolism: a case study

Precise therapeutic decision-making is vital in managing out-of-hospital cardiac arrest. We present an interesting approach where suspected pulmonary embolism could be confirmed by early computed tomography in cardiac arrest. Chest compressions were performed automatically by mechanical devices also during the acquisition of computed tomography data and subsequent thrombolysis. Resume La precision des decisions relatives au traitement est d'importance > dans la prise en charge des arrets cardiaques extrahospitaliers. Sera presentee ici une intervention interessante, qui a permis de confirmer, par une tomodensitometrie (TDM) precoce, une embolie pulmonaire presumee chez une patiente en etat d'arret cardiaque. Les compressions thoraciques, realisees automatiquement par un appareil mecanique se sont poursuivies durant l'acquisition des donnees de la TDM et le traitement thrombolytique qui s'en est suivi

Quantifying Exceptionally Large Populations of \u3ci\u3eAcropora\u3c/i\u3e spp. Corals Off Belize Using Sub-Meter Satellite Imagery Classification

Caribbean coral reefs have experienced dramatic declines in live coral cover in recent decades. Primary branching framework Caribbean corals, Acropora cervicornis (Lamarck, 1816) and Acropora palmata (Lamarck, 1816), have suffered the greatest collapse. Coral Gardens, Belize, is one of few remaining, and perhaps the largest, refugia for abundant, healthy, but undocumented populations of both Acropora species in the Caribbean Sea. In the present study, GeoEye-1 multispectral satellite imagery of a 25 km2 reefal area near Ambergris Caye, Belize, was analyzed to identify live Acropora spp. cover. We used a supervised classification to predict occurrence of areas with live Acropora spp. and to separate them from other benthic cover types, such as sandy bottom, seagrass, and mixed massive coral species. We tested classification accuracy in the field, and new Acropora spp. patches were mapped using differential GPS. Of 11 predicted new areas of Acropora spp., eight were composed of healthy Acropora spp. An unsupervised classification of a red (Band 3):blue (Band 1) ratio calculation of the image successfully separated Acropora corals from other benthic cover, with an overall accuracy of 90%. Our study identified 7.58 ha of reef dominated by Acropora spp. at Coral Gardens, which is one of the largest populations in the Caribbean Sea. We suggest that Coral Gardens may be an important site for the study of modern Acropora spp. resilience. Our technique can be used as an efficient tool for genera-specific identification, monitoring, and conservation of populations of endangered Acropora spp

Oscillatory Correlates of Selective Restudy

Prior behavioral work has shown that selective restudy of some studied items leaves recall of the other studied items unaffected when lag between study and restudy is short, but improves recall of the other items when lag is prolonged. The beneficial effect has been attributed to context retrieval, assuming that selective restudy reactivates the context at study and thus provides a retrieval cue for the other items (Bäuml, 2019). Here the results of two experiments are reported, in each of which subjects studied a list of items and then, after a short 2-min or a prolonged 10-min lag, restudied some of the list items. Participants' electroencephalography (EEG) was recorded during both the study and restudy phases. In Experiment 2, but not in Experiment 1, subjects engaged in a mental context reinstatement task immediately before the restudy phase started, trying to mentally reinstate the study context. Results of Experiment 1 revealed a theta/alpha power increase from study to restudy after short lag and an alpha/beta power decrease after long lag. Engagement in the mental context reinstatement task in Experiment 2 eliminated the decrease in alpha/beta power. The results are consistent with the view that the observed alpha/beta decrease reflects context retrieval, which became obsolete when there was preceding mental context reinstatement