Applications of computational thermodynamics — the extension from phase equilibrium to phase transformations and other properties

Complex equilibria and phase transformations involving diffusion can now be calculated quickly and efficiently. Detailed examples are given for cases which involve varying degrees of non-equilibrium and therefore time-dependence. Despite very good agreement between such calculations and experimental results, many potential end-users are still not convinced that such techniques could be usefully applied to their own specific problems. Friendly graphic interface versions of calculating software are now generally available, so the authors conclude that the most likely source of the reluctance to use such tools lies in the formulation of relevant questions and the interpretation of the results. Although the potential impact of such tools was foreseen many years ago [M. Hillert, Calculation of phase equilibria, in: Conference on Phase Transformations, 1968], few changes in the relevant teaching curricula have taken into account the availability and power of such techniques.     

PID Effect of c-Si Modules: Study of Degradation and Recovery to More Closely Mimic Field Behavior

Recent research demonstrates several failure modes of photovoltaic modules operating under high electric potentials. In crystalline-silicon modules, the predominant failure mode is potential-induced degradation (PID), causing dramatic power losses in systems under high voltage and critical polarity. Environmental conditions highly influence the degradation behavior. The ability to reproduce field observation in the laboratory is challenging and not all stressors can be checked simultaneously. PID and its root cause are not fully understood, but we know several mechanisms are working simultaneously and at varying rates. The main mechanisms are degradation, characterized by ion diffusion and cell shunting, and recovery, driven by temperature, voltage, and potential. Most studies have focused on simulating module degradation using a constant set of parameters. However, field exposure to high voltage is variable, measured by the hour. In 2012, Nagel presented a module stability test with varying environmental conditions, notably temperature. To investigate PID remedies, this research develops a testing procedure that reproduces field observations while understanding that some modules do not degrade in real PV installations under high potentials. Conductive foil is applied to the front side of the module and voltage cycling is introduced to examine potential-induced degradation and potential-induced recovery behavior. The relationship between the two defines a PID stability criterion. Results show general PID sensitivity and suitable remedies for PID affected systems. PID recovery and protection solutions include applying recovery potential at night, and potential shifting, which regulates potential for the module string. This paper explores possible degradation mechanisms, recovery of module output power and PID stability criteria.     

Sputter deposition of thin films on different substrate materials analyzed by means of modulated IR radiometry

Modulated IR radiometry, which is usually applied to sputter-deposited thin films and coatings, to determine the thermal transport properties of the thin films, is applied in this work to analyze the effects of different substrate materials and the effects of the interface coating-substrate on the resulting multi-layer system. For this purpose, a small number of ZrN films of different thickness were deposited on different substrate materials (stainless steel, Si, and glass) and were analyzed with the help of modulated IR radiometry, using heating modulation frequencies in the range from 1 Hz to 100 kHz, allowing depth-resolved thermal measurement from the sub-micron range to the millimeter range. The effects of pre-treatment of the substrates and of the interface between thin films and substrate were also analyzed. Compositional and structural properties of the thin films were obtained by RBS, XRD, and SEM.Preliminary results on the effects of substrates of limited thickness and three-dimensional heat transport, at the transition from coatings of good thermal transport properties to substrates of low thermal transport properties, are reported. A biasing effect related to the deposition process was also identified.     

Single point vibration control for a passive piezoelectric Bernoulli–Euler beam subjected to spatially varying harmonic loads

Passive vibration control of flexible structures can be achieved by bonding piezoelectric layers with attached electric circuits onto an elastic substrate. In this work, a new concept, denoted as single point control (SPC), is presented in order to cancel harmonic vibrations of slender beams. It is shown by an extended version of the Bernoulli–Euler theory for passive smart beams that the deflection or the slope at a specified location along the beam axis is nullified if the electric circuit is tuned and the shape of the piezoelastic layers are properly shaped. The proposed method holds for harmonic loads only, but the spatial part of the distributed external load may be unknown. A three-dimensional electromechanically coupled FE-analysis with ANSYS confirms these results obtained by the one-dimensional theory. The practical relevance of the derived theory becomes evident if optimal resistive-inductive shunts are used. The robustness of passively controlled systems is strongly increased if the piezoelectric layers are shaped according to the presented SPC-theory instead of using spatially uniformly distributed layers.     

高效横剪线——助力钢材加工配送中心

钢材加工配送中心对板材横剪线设备的要求往往很高,因为他们需要加工的材料种类非常丰富.同时,要求得到最好的表面加工质量、精密矫平的落料、锋利的剪切边、精确的剪切角度以及无损伤并整齐的堆垛,这些都是钢材加工配送中心的主要质量要求.钢材加工配送中心加工的板材,如果宽度超过2000mm,料卷直径达到2100mm,这样直径的料卷...     

Field-test of a solar low delta-T Stirling engine

The ultimate aim of a Moroccan–German study is to develop a simple solar pumping system, using the concept of low delta-T Stirling engines. This paper describes the main parts of the engine and presents several experimental measurements made under laboratory and field-test conditions in Morocco. Measurements with flat plate cooler and discontinuous motion of the displacer were conducted to verify two essential recommendations of Kolin in expectation of power-output improvements of the gamma-type engine.     

Proteomic Changes of Activated Hepatic Stellate Cells

Hepatic stellate cells (HSC) are the major cellular drivers of liver fibrosis. Upon liver inflammation caused by a broad range of insults including non-alcoholic fatty liver, HSC transform from a quiescent into a proliferating, fibrotic phenotype. Although much is known about the pathophysiology of this process, exact cellular processes which occur in HSC and enable this transformation remain yet to be elucidated. In order to investigate this HSC transformation, we employed a simple, yet reliable model of HSC activation via an increase in growth medium serum concentration (serum activation). For that purpose, immortalized human LX-2 HSC were exposed to either 1% or 10% fetal bovine serum (FBS). Resulting quiescent (1% FBS) and activated (10% FBS) LX-2 cells were then subjected to in-depth mass spectrometry-based proteomics analysis as well as comprehensive phenotyping. Protein network analysis of activated LX-2 cells revealed an increase in the production of ribosomal proteins and proteins related to cell cycle control and migration, resulting in higher proliferation and faster migration phenotypes. Interestingly, we also observed a decrease in the expression of cholesterol and fatty acid biosynthesis proteins in accordance with a concomitant loss of cytosolic lipid droplets during activation. Overall, this work provides an update on HSC activation characteristics using contemporary proteomic and bioinformatic analyses and presents an accessible model for HSC activation. Data are available via ProteomeXchange with identifier PXD029121.