Low-pressure,thermo-compressive lamination

Lamination of green ceramic tapes is one of the most important technological processes in multilayer ceramic technology. Lamination affects the quality of all 3D structures (e.g., channels, chambers, membranes, etc.). Novel chemical methods of lamination reduce the deformation of 3D structures. However, these methods are useless in the fabrication of thin membranes and structures with thick-film electronic components or electric vias. Therefore, thermo-compressive lamination is still the best solution for the lamination of green ceramic tapes. Low-pressure thermo-compressive lamination with an insert material is presented in this paper. The influence of pressure and Low Temperature Cofired Ceramics (LTCC) material on the compressibility and shrinkage of LTCC, as well as the influence of the insert material on deflection and distortion of the membranes are presented and discussed in this paper.     

APPLICATION OF CONCENTRATED SOLAR RADIATION TO HIGH TEMPERATURE DETOXIFICATION AND RECYCLING PROCESSES OF HAZARDOUS WASTES

In many cases, hazardous wastes are subject to thermal treatment at elevated temperatures. Some types of wastes do not have a sufficient calorific value to cover the heat demand of the high temperature process. For thermal treatment of e.g. filter residues, dusts, sulfuric acid, aluminium dross, foundry sand, or waste water, supplementary energy supply is needed. The specific energy demand ranges from 0.5 to 2.5 kWh/kg (2–10 MJ/kg). An important aim of process optimisation is the reduction of (fossil) energy consumption and exhaust gas flow. Concentrated solar energy promises advantages when applied to high energy consuming waste treatment processes with regard to substitute fossil or electric energy consumption, to reduce CO₂ emissions, and exhaust gas flow. In parallel to conceptional studies, a solar-heated rotary kiln mini-plant has been designed and constructed for tests in the DLR solar furnace. The tests will give indications of boundary conditions for solar thermal treatment or conversion of selected hazardous materials.     

Ionic Space‐Charge Depletion in Lithium Fluoride Thin Films on Sapphire (0001) Substrates

Lithium fluoride thin films with various thicknesses have been grown on c‐plane sapphire substrates by radio‐frequency sputtering. The thin films are granular with a preferential [111] orientation of the grains. Thickness‐dependent measurements allow the separation of bulk and interface conductions. The normalized conductance decreases linearly with decreasing LiF layer thickness with a negative extrapolated intercept. DC polarization, AC impedance spectroscopy and electromotive force measurement indicate depletion of lithium ion vacancies as majority charge carriers and hence a negative space‐charge potential. A generalized Mott–Schottky approach within the model of heterogeneous doping fully explains the entire boundary defect chemistry.     

Rezente Mängel der Leichenschau und ihre historischen Ursachen: Eine Analyse aus medizingeschichtlicher Sicht

In recent years, the enactment of uniform national regulations concerning postmortem examination has become a persistent demand. There is strong criticism of the reliability of coroner's inquest: The education of most of the coroners in forensic medicine is found to be insufficient, and many experts report that medical examiners partly are neglectful for the inquest. The classification of the manner of death is also said to be deficient, the rate of misdiagnosis being only little below 50 %. Thus much emphasis is put on demanding a reinforced training of doctors in the field of the external examination of corpses. But only few of those reports make allowance for the fact that that most of the present deficiencies have their origin in the 19th century. As a matter of fact, from the outset the practise of coroner's inquest gave rise to criticism. Thus the present article traces the historical roots of postmortem examination in Germany. Special emphasis is placed on a comparison between the infancies of coroner's inquest and the current state. Actual and historical imperfections in the system of postmortem examination and striking similarities are pointed out.      

Simulation of Flow and Mass Transport in a Meander Microchannel Subject to Electroosmotic Pumping

We have investigated the flow and mass transport within an electroosmotically pumped incompressible liquid through a meander microchannel system. We employ two-dimensional, time-dependent finite element simulations in conjunction with a matched asymptotic treatment of the electrical double layers. The electroosmotic pumping is realized for two idealized and two realistic electrical fields, while a pressure-driven flow is used for comparison. We focus on the aspects of the electroosmotic transport.

We find for most of the electroosmotically driven cases rather complex flow fields, involving recirculation regions. These recirculation regions in all cases increase dispersion. (i) The least dispersion is associated with a plug-type velocity profile, which is obtained for an idealized purely wall-tangential orientation of the electrical field. (ii, iii) We find that both the idealized horizontal electrical field and the real electrical field between two vertical plates give considerably higher dispersion than the pressure-driven flow. Vertical plate electrodes, therefore, do not allow for a electrical field, which minimizes dispersion. (iv) The arrangement of two point electrodes at the in and out sections likewise proves to be no optimal means to reduce dispersion beyond the pressure-driven flow. Thus, meander geometries of channels, in general, cause severe problems if electroosmotic pumping needs to be achieved in combination with minimized dispersion.     

Verhaltensbasierte Verkettung von Internetsitzungen

Die Analyse der Aktivit?ten eines Internet-Nutzers ist über l?ngere Zeit in der Regel nur mit Kenntnis der bei vielen Internet-Zugangsprovidern mindestens einmal t?glich wechselnden IP-Adressen m?glich. Verwendet der Nutzer zudem einen Anonymisierungsdienst, sollte eine Verkettung der Nutzer-Aktivit?ten auch für den Zugangsprovider unm?glich sein. Der Beitrag zeigt, dass eine verhaltensbasierte Verkettung dennoch m?glich ist und verbreitete Anonymisierungsl?sungen in der Praxis einen deutlich geringeren Schutz vor Beobachtung bieten, als bisher angenommen.     

The social bookmark and publication management system bibsonomy

Social resource sharing systems are central elements of the Web 2.0 and use the same kind of lightweight knowledge representation, called folksonomy. Their large user communities and ever-growing networks of user-generated content have made them an attractive object of investigation for researchers from different disciplines like Social Network Analysis, Data Mining, Information Retrieval or Knowledge Discovery. In this paper, we summarize and extend our work on different aspects of this branch of Web 2.0 research, demonstrated and evaluated within our own social bookmark and publication sharing system BibSonomy, which is currently among the three most popular systems of its kind. We structure this presentation along the different interaction phases of a user with our system, coupling the relevant research questions of each phase with the corresponding implementation issues. This approach reveals in a systematic fashion important aspects and results of the broad bandwidth of folksonomy research like capturing of emergent semantics, spam detection, ranking algorithms, analogies to search engine log data, personalized tag recommendations and information extraction techniques. We conclude that when integrating a real-life application like BibSonomy into research, certain constraints have to be considered; but in general, the tight interplay between our scientific work and the running system has made BibSonomy a valuable platform for demonstrating and evaluating Web 2.0 research.     

Zustandsänderung und Aufheizung des Gases in Seitenkanalverdichtern

Zusammenfassung Seitenkanalverdichter unterliegen trotz ihrer geringen Druckverh?ltnisse im Teillastbereich erheblichen thermischen Belastungen. Dadurch steigt nicht nur die Verdichtungsendtemperatur und die Maschinenbelastung, sondern mit steigender Maschinentemperatur erfolgt auch eine erhebliche Aufheizung des Gases bereits im Eintrittsbereich, wodurch die Arbeitsübertragung beeinflu?t wird. Die Resultate experimenteller Untersuchungen zeigen, da? die Aufheizung des Gases besonders im Eintrittsbereich des Seitenkanals erfolgt und dadurch die Arbeitsübertragung im vorderen Bereich stark verlustbehaftet erfolgt. Die Folge davon sind sehr hohe Polytropenexponenten bei gro?en Druckverh?ltnissen im Teillastbereich, die zu einer gro?en W?rmezufuhr an das Gas führen und den Wirkungsgrad der Maschinen mindern.     

Einsatz von Entspannungsturbinen in CO2-Laseranlagen

Zusammenfassung Im Resonator von Laseranlagen werden ca. 20% der zugeführten Energie für den Laserstrahl genutzt. 80% der zugeführten Gesamtenergie werden mit dem Lasergas ungenutzt aus dem Resonator in den nachfolgenden W?rmeübertrager abgeführt. Um den Anlagenwirkungsgrad von Laseranlagen zu erh?hen, soll die ungenutzte Austrittsenergie aus dem Resonator in einer nachgeschalteten Entspannungsturbine in mechanische Energie umgesetzt werden, die zum Antrieb des Lasergasverdichters genutzt wird. Dadurch kann der Verdichter mit der vorhandenen Proze?energie angetrieben werden und der Anlagenwirkungsgrad vonη _A bis 0,20 aufη _A bis 0,34 erh?ht werden. Durch thermodynamische Proze?untersuchungen werden die erreichbaren Wirkungsgradsteigerungen von Laseranlagen ausgewiesen und die optimalen Parameterbereiche für die Druck-und Temperaturverh?ltnisse ermittelt. Das Leistungsverh?ltnis der gewonnenen Turbinenleistung zur notwendigen Verdichterleistung wird angegeben.