Influence of Weathering on Pore Size Distribution of Soft Rocks

Soft rocks can weather and lose their structure within a short time due to drying out and rewetting. Thus they are very sensitive to weathering. Since these rocks are often found in the shallow subsurface, they are of great practical relevance in the foundation of constructions. The rock properties change during the weathering process. Particularly relevant is the softening of the material and the decrease of its mechanical properties, which are determined typically using mechanical laboratory or field tests. The objective of this study is to examine in more detail how the microstructure of rocks changes over the course of weathering, which results in a decrease in mechanical properties. Sulfate rocks of the Grabfeld-Formation in Stuttgart, Germany were investigated. Using XRD analyses it was revealed that initially a chemical weathering processes occurs whereby the rocks leach out, followed by a physical weathering process. Investigations with a mercury porosimeter showed that during chemical weathering the intraaggregate pore content greatly increases, whereas the proportion of interaggregate pores only slightly increases

Evaluating an enhanced thermal response test (ETRT) with high groundwater flow

Enhanced thermal response tests (ETRT) enable the evaluation of depth-specific effective thermal conductivities. Groundwater flow can significantly influence the interpretation of ETRT results. Hence, this study aims to critically evaluate an ETRT with high groundwater flow (> 0.2 m d$^{−1}$). Different approaches in determining the specific heat load of an ETRT are compared. The results show that assuming constant electrical resistance of the heating cable with time can account for an inaccuracy of 12% in the determination of effective thermal conductivities. Adjusting the specific heat loads along the borehole heat exchanger (BHE) depth, the specific heat loads vary within 3%. Applying the infinite line source model (ILS) and Péclet number analysis, a depth–average hydraulic conductivity is estimated to be 3.1 × 10$^{–3}$ m s$^{−1}$, thereby, confirming the results of a pumping test of a previous study. For high Darcy velocities (> 0.6 m d$^{−1}$), the uncertainty is higher due to experimental limitations in ensuring a sufficient temperature increase for the evaluation (ΔT > 0.6 K). In these depths, the convergence criterion of Δλeff/λeff < 0.05/20 h for the ILS sequential forward evaluation cannot be achieved. Thus, it can be concluded that time-averaging of the heat load by monitoring voltage and current during ETRT is essential. Therefore, the specific heat load adjustment along the heating cable is recommended. To improve the estimation of depth-specific effective conductivities with high groundwater flow and to reduce the sensitivity towards temperature fluctuations (ΔT ~ 0.1 K), measures for applying higher specific heat loads during the ETRT are essential, such as actions against overheating of the cable outside the BHE

Methodology of calculation of construction and hydrodynamic parameters of a foam layer apparatus for mass-transfer processes

Промислова реалізація методу стабілізації газорідинного шару дозволяє значно розширити галузь застосування пінних апаратів і відкриває нові можливості інтенсифікації технологічних процесів з одночасним створенням маловідходних технологій. У статті встановлені основні параметри, що впливають на гідродинаміку пінних апаратів, розглянуті основні конструкції та режими роботи пінних апаратів. Виявлено зв'язок гідродинамічних параметрів. Розглянуто гідродинамічні закономірності пінного шару. Вказані фактори, що впливають на процес масообміну, як в газовій, так і в рідкій фазах. Проведений аналіз ряду досліджень показав, що перспективним напрямком інтенсифікації процесу масообміну є розробка апаратів з трифазним псевдозрідженим шаром зрошуваної насадки складних форм із сітчастих матеріалів. Отже, необхідне проведення спеціальних досліджень гідродинамічних режимів роботи апарату з сітчастою насадкою і визначенням параметрів, що впливають на швидкість переходу насадки з одного режиму в інший.Industrial implementation of the stabilization method of the gas-liquid layer can significantly expand the field of use of foaming apparatus and opens up new opportunities for intensifying technological processes with the simultaneous creation of low-waste technologies. The article establishes the basic parameters influencing the hydrodynamics of foam apparatus, considers the basic constructions and operating modes of foam apparatus. The connection of hydrodynamic parameters is revealed. The hydrodynamic laws of the foam layer are considered. The indicated factors affecting the process of mass transfer, both in the gas and in the liquid phases. The conducted analysis of a number of studies showed that the perspective direction of intensification of the mass transfer process is the development of apparatuses with a three-phase fluidized bed of an irrigated nozzle of complex forms with mesh materials

A Nondifferentiable Optimization Approach to Ratio-Cut Partitioning

We propose a new method for finding the minimum ratio-cut of a graph. Ratio-cut is NP-hard problem for which the best previously known algorithm gives an O(log n)-factor approximation by solving its dually related maximum concurrent flow problem. We formulate the minimum ratio-cut as a certain nondifferentiable optimization problem, and show that the global minimum of the optimization problem is equal to the minimum ratio-cut. Moreover, we provide strong symbolic computation based evidence that any strict local minimum gives an approximation by a factor of 2. We also give an efficient heuristic algorithm for finding a local minimum of the proposed optimization problem based on standard nondifferentiable optimization methods and evaluate its performance on several families of graphs. We achieve O(n^1&apos;6) experimentally obtained running time on these graphs

Immature rat seminiferous tubules reconstructed in vitro express markers of Sertoli cell maturation after xenografting into nude mouse hosts

Sertoli cells undergo a maturation process during post-natal testicular development that leads to the adult-type Sertoli cell, which is required for spermatogenesis. Understanding Sertoli cell maturation is therefore necessary to gain insight into the underlying causes of impaired spermatogenesis and male infertility. The present study characterized the cellular and molecular differentiation of Sertoli cells in a xenograft model of mammalian testicular development. Immature rat Sertoli cells were cultured in a three-dimensional culture system to allow the formation of cord-like structures. The in vitro Sertoli cell cultures were then grafted into nude mice. Sertoli cell proliferation, morphological differentiation and mRNA expression of Sertoli cell maturation markers were evaluated in xenografts. Sertoli cell proliferation significantly decreased between 1 and 4 weeks (6.7 ± 0.9 versus 1.2± 0.1%, P < 0.001), and was maintained at low levels thereafter. Sertoli cell cord-like structures significantly decreased between 1 and 4 weeks (59.6 versus 21%, P < 0.05), whereas Sertoli cell tubules were more frequently observed after 4 weeks (13.3 versus 73.1%, P < 0.05). Furthermore, expression of androgen binding protein, transferrin and follicle stimulating hormone receptor, markers for mature Sertoli cells, was detected after 1 week of grafting and increased significantly thereafter. We conclude from these results that rat Sertoli cells continue maturation after xenografting to the physiological environment of a host. This model of in vitro tubule formation will be helpful in future investigations addressing testicular maturation in the mammalian testis

GEO.Cool : Kühlung mit oberflächennaher Geothermie - Möglichkeiten, Grenzen, Innovation -

Das Verbundprojekt GEO.Cool von Partnern im Landesforschungszentrum Geothermie (LFZG) hat zum Ziel, Möglichkeiten sowie Grenzen der Kühlung mit oberflächennaher Geothermie in interdisziplinärer Arbeit zu erheben und daraus Impulse für Innovationen in diesem Bereich zu gewinnen. Das Vorhaben ist in die folgenden sechs Arbeitspakete (AP) gegliedert: AP 1: Bedarfe und Systemaspekte AP 2: Systemtechnik und Planung von Anlagen zur Kühlung mit oberflächennaher Ge-othermie AP 3: Analyse von Best-Practice-Beispielen AP 4: Thermisches und hydrogeologisches Verhalten des Untergrunds AP 5: Genehmigungspraxis und Grenzwerte AP 6: Synopse, Innovationspotenzial und Transfer. Das Projekt hat eine Laufzeit vom 23.01.2017 bis zum 30.09.2019 (Förderzeitraum für alle Arbeitspakete und Projektpartner)

GEO.Cool : Kühlung mit oberflächennaher Geothermie - Möglichkeiten, Grenzen, Innovation -

In dem durchgeführten Verbundvorhaben arbeiteten zum einen die Fachgebiete Geologie/Geothermie sowie Anlagen- und Systemtechnik von geothermischer Kältegewinnung und Kältenutzung der Projektpartner interdisziplinär zusammen, um den aktuellen Wissensstand der Kühlung mittels oberflächennaher Geothermie fachübergreifend zu erfassen, zu bewerten und Schnittstellenprobleme zu bearbeiten. Aus dieser interdisziplinären Betrachtungsweise wurden ganzheitliche Hinweise zur Optimierung des geothermischen Kühlpotenzials sowie Anstöße für technische und planerische Innovationen für die Praxis entwickelt und in diese transferiert. Zu folgenden Zielen wurden Beiträge erarbeitet: - Steigerung der Energieeffizienz der Kühlung und Kältebereitstellung - Nutzung regenerativer Energien zur Kühlung und Kältebereitstellung - Begrenzung der thermischen Belastung des Untergrunds und des Grundwassers - Minimierung der Schäden und Risiken durch den Eingriff in den Untergrun