Kinetic separation of vaporous alcohol-water mixtures : modeling, experiments, feasibility study

Separation processes play an important role in the petrochemical and chemical industry and are to a large extent responsible for the high energy consumption in this sector. For this reason the chemical industry is continuously looking for more efficient separation processes. Besides energy consumption also the replacement or reduction of the use of hazardous chemicals is an important issue. The work performed in this thesis focuses on the development of the kinetic separation process FricDiff. The aim is to get more insight in this separation technology and to examine if FricDiff, both from an economical and environmental perspective, can be an attractive technology for the chemical industry. FricDiff can be classified as a kinetic separation process, because separation is achieved as a result of differences in transport velocities of the components of a gas or vapor mixture when diffusing through an auxiliary component. This auxiliary component is intentionally added to the system to achieve a separation and is referred to as the sweep gas or separating agent. The main focus of this thesis is to study the separation of alcohol-water vapor mixtures with FricDiff using nitrogen or carbon dioxide as the sweep gas. A typical FricDiff unit consists of two compartments separated by a porous, nonselective screen. The vaporous mixture is introduced to one compartment and the sweep gas to the other. While flowing through the unit, material is selectively exchanged between the two compartments. Two product streams leave the unit, one enriched in the slower diffusing mixture component(s) and one enriched in the faster diffusing component(s). In the unit multi-component mass transfer through the porous screen plays an important role and it is examined in more detail in Chapter 3. In this chapter six models for multi-component mass transport through pores and porous media are compared. Differences between the models are observed, but they are generally small and for engineering purposes most probably of minor importance. In Chapter 4 three models are developed to describe the separation process in a tubular FricDiff module. With these three models the influence of process conditions and barrier characteristics on the performance of the module are examined. It is shown that the mode of operation (co-current vs. countercurrent), the sweep gas to feed mixture ratio, absolute pressure level, pressure gradients over the porous barrier, type of sweep gas, barrier thickness and barrier pore size all influence the separation process and can be used for module and process optimization. Chapter 5 shows that for FricDiff modules equipped with thin barriers of high porosity concentration boundary layer in the compartments have a large impact on the separation process. These boundary layers give rise to additional resistances to mass transfer. In order to describe these resistances multi-component Sherwood correlations are derived that give an accurate description of the transport of mixture components through these boundary layers. In Chapter 6 experimental results are presente on the separation of helium-argon gas mixtures and the separation of isopropyl alcohol-water vapor mixtures with nitrogen as the separating agent. The main focus of this chapter is the validation of the numerical models developed in Chapter 4 with experimental data. With a value of the porosity-tortuosity (??/??2) parameter fitted and a value of the pore size determined from permeation experiments, generally a good agreement is obtained between experimental data and numerical results. The performance of a unit in which the FricDiff separation process is combined with condensation of vapors on the wall of the sweep gas compartment is studied numerically in Chapter 7. It is shown that the condensation of vapor components within the unit can have a positive effect on the separation when the faster diffusing component also condenses at a higher rate. Another goal of the thesis is to search for viable applications for FricDiff in industrial separation processes. For this reason an exergy analysis is performed in Chapter 8 to determine the thermodynamic efficiency of pervaporation, distillation, a single FricDiff unit and a cascade of FricDiff units. For the separation of an isopropyl alcohol-water mixture the lowest efficiencies are obtained with the cascade of FricDiff units. This is a result of the irreversibilities inherent to the separation process (intermingling of mixture components and sweep gas) and the irreversibilities associated with the heat transfer steps in each stage of the cascade. The entropy production in a single FricDiff unit is limited and therefore hybrid distillation-FricDiff configurations are studied in Chapter 9. This chapter studies several process configurations for isopropyl alcohol-water and ethanol-water dehydration processes. Application of FricDiff as a final purification step for ethanol-water separations can be beneficial from an energetic perspective, but the extra investments that have to be made, make the process economically unattractive

The ‘Demange drawings’: known and unknown malacological contribu- tions of Victor Demange (1870-1940)

In the Bavay archives a collection of drawings of Vietnamese land and freshwater snails is present, which have never been published. They originate from Victor Demange who had them made by a local raftsman. The drawings are here reproduced and some biographical data on Demange, and his contributions to malacology, are presented.This item is freely available and free to download from the Folia Conchyliologica website. The attached article is the published version.This item is freely available and free to download from the Folia Conchyliologica website. The attached article is the published version

Annotated type catalogue of the Bothriembryontidae and Odontostomidae (Mollusca, Gastropoda, Orthalicoidea) in the Natural History Museum, London

The type status is described for specimens of 84 taxa classified within the families Bothriembryontidae and Odontostomidae (superfamily Orthalicoidea) and kept in the Natural History Museum, London. Lectotypes are designated for Bulimus (Liparus) brazieri Angas, 1871; Bulimus broderipii Sowerby I, 1832; Bulimus fuligineus Pfeiffer, 1853; Helix guarani d’Orbigny, 1835; Bulimus (Tomigerus) ramagei E.A. Smith, 1890; Helix rhodinostoma d’Orbigny, 1835; Bulimus (Bulimulus) ridleyi E.A. Smith, 1890. The type status of the following taxa is changed to lectotype in accordance with Art. 74.6 ICZN: Placostylus (Euplacostylus) cylindricus Fulton, 1907; Bulimus pyrostomus Pfeiffer, 1860; Bulimus turneri Pfeiffer, 1860. The following taxon is synonymised: Bulimus oblitus Reeve, 1848 = Bahiensis neglectus (Pfeiffer, 1847).This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.NHM Repositor

A snail in the long tail: a new Plekocheilus species collected by the ‘Comisión Científica del Pacífico’ (Mollusca, Gastropoda, Amphibulimidae)

© Abraham S.H. Breure, Rafael Araujo. Among the historical collection gathered by the ‘Comisión Científica del Pacífico’ during 1862–1865, type material was found of one of the species described on the basis of the material collected shortly afterwards. Inspection of the types revealed that only one specimen may be considered as type material of Bulimus aristaceus Crosse, 1869; this specimen is now designated as the lectotype. The other specimens are described as a new species, Plekocheilus (P.) cecepeus.Peer Reviewe

Past, present and future of historical information science

Der Bericht evaluiert Entwicklungen und Einflüsse von Forschungen im Bereich der empirisch orientierten Geschichtswissenschaft und deren rechnergestützten Methoden. Vorgestellt werden ein Forschungsparadigma und eine Forschungsinfrastruktur für die zukünftige historisch orientierte Informationswissenschaft. Die entscheidenden Anstöße dafür kommen eher von Außen, also nicht aus der scientific community der Assoziation for History and Computing (AHC). Die Gründe hierfür liegen darin, dass die AHC niemals klare Aussagen darüber gemacht hat, welches ihre Adressaten sind: Historiker, die sich für EDV interessieren, oder historisch orientierte Informationswissenschaftler. Das Ergebnis war, dass sich keine dieser Fraktionen angesprochen fühlte und kein Diskurs mit der 'traditionellen' Geschichtswissenschaft und der Informationswissenschaft zustande kam. Der Autor skizziert ein Forschungsprogramm, das diese Ambiguitäten vermeidet und die Ansätze in einer Forschungsinfrastruktur integriert. (ICAÜbers)'This report evaluates the impact of two decades of research within the framework of history and computing, and sets out a research paradigm and research infrastructure for future historical information science. It is good to see that there has been done a lot of historical information research in the past, much of it has been done, however, outside the field of history and computing, and not within a community like the Association for History and Computing. The reason is that the AHC never made a clear statement about what audience to address: historians with an interest in computing, or historical information scientists. As a result, both parties have not been accommodated, and communications with both 'traditional' history and 'information science' have not been established. A proper research program, based on new developments in information science, is proposed, along with an unambiguous scientific research infrastructure.' (author's abstract

Data Showcases: the Data Journal in a Multimodal World

   As an experiment, the Research Data Journal for the Humanities and Social Sciences (RDJ) has temporarily extended the usual format of the online journal with so-called ‘showcases’, separate web pages containing a quick introduction to a dataset, embedded multimedia, interactive components, and facilities to directly preview and explore the dataset described. The aim was to create a coherent hyper document with content communicated via different media (multimodality) and provide space for new forms of scientific publication such as executable papers (e.g. Jupyter notebooks). This paper discusses the objectives, technical implementations, and the need for innovation in data publishing considering the advanced possibilities of today's digital modes of communication. The data showcases experiment proved to be a useful starting point for an exploration of related developments within and outside the humanities and social sciences. It turns out that small-scale experiments are relatively easy to perform thanks to the easy availability of digital technology. However, real innovation in publishing affects organization and infrastructure and requires the joint effort of publishers, editors, data repositories, and authors. It implies a thorough update of the concept of publication and adaptation of the production process. This paper also pays attention to these obstacles to taking new paths

Factors associated with the allocation of carbohydrates to bunch dry matter production in oil palm (Elaeis guineensis Jacq.)

This thesis reports on the factors relevant to the allocation of assimilates to oil palm bunch dry matter (DM) production, based on an extensive set of growth and yield records from experiments in Papua New Guinea and Malaysia.Basically, assimilates from gross assimilation of the canopy are first used for maintenance of existing biomass (maintenance respiration). The remaining assimilates are converted into structural DM production. Carbohydrate requirements for components of DM production are derived from conversion factors based on the biochemical composition of the DM. Maintenance respiration is estimated as the difference between gross photosynthetic production, derived from the assimilation light response curve of individual leaves, and the amount of carbohydrate required for DM production. About 50% of total gross assimilation is lost in maintenance respiration; losses appear to be more related to growth rate than to the amount of existing biomass.The allocation of assimilates to bunch DM production has a low priority in the carbon budget. Thus bunch production starts when certain minimum requirements of assimilates for maintenance respiration and vegetative growth have been met; above this critical value additional assimilates are virtually all utilized for economic yield. This implies that yield will benefit greatly from measures which increase photosynthetic production. Further, that yield will respond strongly to a reduction in internal competition, in terms of assimilates, from vegetative growth and maintenance respiration.This thesis shows that the efficiency of converting intercepted radiation into carbohydrates for dry matter production decreased with the expansion of the crown leaves, which might be linked to the resulting increase in maintenance respiration losses. These losses were apparently not compensated by an increase in photosynthetic production. The efficiency increased again when crown expansion was complete, which appears to be due to improved light distribution consequent on an observed increment in light penetration. These effects of changing levels of interception and distribution of sunlight on efficiency were more pronounced as the planting density increased, and resulted in marked differences in yield trends with age between densities. The end result was a decrease in optimum density for current yield until 12 to 13 years from planting, followed by a strong increase. It is concluded that optimal density for cumulative yield might be increased by measures which optimize the balance between light interception by and distribution of light over the foliage. The response of improved light distribution would be enhanced by selection for net assimilation rate of the leaves.Palms differ considerably in rate of leaf expansion. As expected, this is reflected in total DM production per palm, which to a great extent benefits bunch yield.DM production per palm was also increased through reducing the incidence of deficiency of magnesium, an essential component of the chlorophyll molecule; again, the benefit is mainly obtained in oil yield. Selection for high magnesium status is feasible and appears to be an efficient way to increase oil yield.increasing bunch yield, at a certain level of DM production, implies reducing requirements for vegetative growth (increase of the Bunch index). ideally, a reduction in vegetative DM production should be restricted to nonphotosynthesizing tissue. This aim can be achieved by selection for high leaf area ratio (LAR), defined for this crop as the ratio of new leaf area produced to new dry matter used for vegetative growth. Another method might be to reduce the period of crown expansion subsequent to canopy closure; from this stage onwards, no further increase in gross assimilation occurs but additional crown expansion continues to increase requirements for vegetative growth and maintenance respiration. Therefore, speed of crown expansion should be combined with a reduction in crown expansion time. These two objectives can be achieved by selection for so-called rapid expansion (RER) ideotypes, i.e. a high ratio of leaf area at maximum expansion rate and a relatively low final size.The observation that Palms selected on the basis of increased light interception and reduced vegetative requirements do indeed have higher BI, indicates that selection for ideotypes (defined as biological models which are expected to perform or behave in a predictable manner within a defined environment), is feasible. This finding justifies exploring other methods which, through manipulation of the carbon budget, would increase assimilates available for bunch dry matter production. Selection for increased photosynthetic production at light saturation, and also for reduction of leaf maintenance requirements, may be rewarding. Screening of progenies in the nursery on the basis of increased photosynthetic production of the leaf surface and for reduced maintenance respiration, as well as for leaf-Mg level and LAR, may be possible.To permit large scale testing of the response of yield to ideotype selection , a method to improve the conventional time- consuming method of growth recording is proposed. The main finding is that rate of leaf production, which is the key for an instant method of growth recording, can be obtained by counting the leaf bases on the trunk. The proposed, so-called one-shot" method of growth recording, in particular, resulted in an efficient selection of progenies on the basis of BI.In addition to vegetative growth and maintenance respiration, the development of bunches competes with inflorescence primordia for carbohydrates. Fruiting activity also, to a certain extent, competes with vegetative growth. Thus if the potential sink size for fruit bunch production is not fully uti1ized, palms tend to produce excessive vegetative growth. A direct implication is that adequate pollination is essential, as could be demonstrated by comparing vegetative growth of similar planting material under poor and adequate assisted pollination.The supply of carbohydrate affects all the components which determine the number of bunches (sex ratio, abortion, and leaf production) and those which determine their mean weight. The latter can be divided into the frame (stalk and empty. spikelets) and the fruit (the product of spikelet number, ,flower number per spikelet, fruit set and the mean weight of individual fruits). The number of flowers per spikelet and sex are both determined just prior to spikelet initiation. For floral abortion the critical stage is at the onset of rapid expansion of the inflorescences, about 10 leaves prior to anthesis. It was also at this stage that the first response of frame weight to carbohydrate supply was observed. The weight of the frame is further affected at two earlier developmental stages: first, when the central axis ceases to be meristematic and, second, just prior to spikelet initiation. The latter stage, which is about two years before harvest, is thus the most important stage in inflorescence development in that here key components of bunch yield are affected by the supply of carbohydrate.An analysis of components of oil yield at different spacings (varying levels of carbohydrate supply) showed that components which are determined at an advanced stage in inflorescence development (floral abortion and stalk weight) are more sensitive to changes in carbohydrate supply than those determined at an earlier developmental stage (sex ratio and number of flowers per spikelet). These finding are supported by an analysis of response of yield components to different levels of fruit bunch removal (disbudding). Moreover, in respect of abortion, it appears that initial response to shortage of carbohydrate mainly decreases the number of female if this shortage is prolonged both sexes abort.Insect pollination, which replaced the method of assisted pollination in the course of this study, appears to have increased optimal planting density by at least 5 palms per ha. This finding is derived from a measured increase in extraction of oil and kernels in response to planting density, and from a decrease in vegetative growth due to, as mentioned earlier, an increase in sink strength of the fruits

Ancestors : a challenge to the Oruuano Church of Namibia

Text in EnglishOruuano is an Independent Church in Namibia founded in 1955 because of members of the Herero community breaking away from the Rhenish Mission Church. Oruuano has the same doctrinal position as the Evangelical Lutheran Churches. In all church services it uses the standard Lutheran liturgical forms and the Otjiherero Lutheran hymnal. Belief in the ancestors is strong among the Herero. It is centred around the holy fire that is found between the main house of the head man and the cattle's kraal. The church does not acknowledge the ancestors, but it allows its members to venerate their ancestors outside the church. The church's approach is that of tacit consent. This dissertation discusses this approach and concludes that Oruuano cannot remain silent on the ancestors any longer. Time has come to deal with it theologically, showing the supremacy of Christ, while integrating Herero traditional practices and spirituality with the worship and practice of Oruuano.Christian Spirituality, Church History and MissiologyM.Th. (Missiology

Virtual historical landscapes

Using 3D computer graphics technology, we are able to create virtual reconstructions of (almost completely) disappeared landscapes. The applications of these virtual historic landscapes range from landscape archaeology, edutainment to landscape planning. Although computer graphics technology matured and photo-realistic representations are achieved, the creation of realistic virtual reconstructions remains problematic. For a realistic user experience, we need to know which cues influence the user perception. However, poor-defined visualization requirements for 3D virtual historic landscapes leave us with the question ‘How good is good enough?’ This article discusses the search for a decisive variable to let users perceive the virtual historic landscape, focusing on image quality and contents of the virtual historic landscape. The virtual reconstruction of Palace Honselaarsdijck, a 17th century real-estate of stadtholder Frederick Henry (1584-1647), and its surrounding landscape is used as a case study. Using old maps, image processing and GIS software the historic terrain model was generated. By application of a 3D historic object library, the virtual landscape was decorated with wind mills, houses, churches and so forth. Finally, the virtual historic landscape was completed with atmospheres, water and vegetation. The result is a full-decorated and rendered virtual historic landscape. From a preliminary user test, the researchers learned that the contents of the virtual historic landscape are more important than the image quality. Future work will focus on what the identifying landscape features for a realistic user experience are, and how to communicate uncertainty inside the virtual landscape. The expectation is  that the work contributes to the realization of virtual historic landscape on a large-scale to communicate landscape information to the broad public