The dissociation of (a+c) misfit dislocations at the InGaN/GaN interface

(a+c) dislocations in hexagonal materials are typically observed to be dissociated into partial dislocations. Edge (a+c) dislocations are introduced into (0001) nitride semiconductor layers by the process of plastic relaxation. As there is an increasing interest in obtaining relaxed InGaN buffer layers for the deposition of high In content structures, the study of the dissociation mechanism of misfit (a+c) dislocations laying at the InGaN/GaN interface is then crucial for understanding their nucleation and glide mechanisms. In the case of the presented plastically relaxed InGaN layers deposited on GaN substrates we observe a trigonal network of (a+c) dislocations extending at the interface with a rotation of 3 degrees from directions. High resolution microscopy studies show that these dislocations are dissociated into two Frank-Shockley 1/6 partial dislocations with the I1 BSF spreading between them. Atomistic simulations of a dissociated edge (a+c) dislocation revealed a 3/5 atom ring structure for the cores of both partial dislocations. The observed separation between two partial dislocations must result from the climb of at least one of the dislocations during the dissociation process, possibly induced by the mismatch stress in the InGaN layer.Comment: This is a submitted version of the manuscript published in Journal of Microscop

Fjords as Aquatic Critical Zones (ACZs)

In recent decades, the land-ocean aquatic continuum, commonly defined as the interface, or transition zone, between terrestrial ecosystems and the open ocean, has undergone dramatic changes. On-going work has stressed the importance of treating Aquatic Critical Zones (ACZs) as a sensitive system needing intensive investigation. Here, we discuss fjords as an ACZ in the context of sedimentological, geochemical, and climatic impacts. These diverse physical features of fjords are key in controlling the sources, transport, and burial of organic matter in the modern era and over the Holocene. High sediment accumulation rates in fjord sediments allow for high-resolution records of past climate and environmental change where multiple proxies can be applied to fjord sediments that focus on either marine or terrestrial-derived components. Humans through land-use change and climatic stressors are having an impact on the larger carbon stores in fjords. Sediment delivery whether from accelerating erosion (e.g. mining, deforestation, road building, agriculture) or from sequestration of fluvial sediment behind dams has been seriously altered in the Anthropocene. Climate change affecting rainfall and river discharge into fjords will impact the thickness and extent of the low-salinity layer in the upper reaches of the fjord, slowing the rate of the overturning circulation and deep-water renewal – thereby impacting bottom water oxygen concentrations

Model of "pump aggregate - pipeline" system with controled driving match on diagnostic requirements

Przedmiotem pracy jest konstrukcja modelu systemu "zespół pompowy - przewód" składającego się z przemiennika częstotliwości, silnika napędowego, pompy oraz rurociągu. Idea pracy systemu opiera się na stabilizacji ciśnienia tłoczenia wody w rurociągu poprzez częstotliwościową regulację prędkości silnika napędzającego pompę tłoczącą. W pracy przedstawiono topologię systemu oraz jego opis analityczny, który zostanie wykorzystany jako model diagnostyczny w dalszych badaniach. Układ opisano wykorzystując modelowanie matematyczne, modelowanie neuronowe oraz charakterystyki statyczne. Szczególną uwagę zwrócono na dobór modelu neuronowego - porównując uzyskane z niego wyniki z danymi pomiarowymi.The aim of the paper is construction of "pump aggregate - pipeline" system model consists of frequency converter, driving motor, pumps and pipeline. Idea of system's work is based on pressure stabilization in pipeline through frequency control of speed of motor which drives the pump. The paper presents the topology of analysed system and its analytical description which will be taken advantage as diagnostic model in farthest research. The system is described through using mathematical modeling, neuron modeling and static characteristics. There was payed the special attention on selection of neuron model comparing received results to measuring data

Computer simulations of pumps drive system during additional induction motor connecting

The problem of suitable water pump drive system selection step forward in many water pump stations. It should be a compromise among the price of drive and the best technical parameters. The most imortant technical parameter for water receiver is pressure. It should be constant. The paper presents results of computer simulations of pump drive system during adding the second induction motor supply from power network. There is shown the matemathical model of PWM inverter, induction motor and the characteristic of pump. The pump drive system consists of two induction motors - one supply from PWM inverter, the second from power network. The second induction motor is connected when demand for water is higher than delivery of a pump fed by the controled motor

Trophic niches of macrobenthos : Latitudinal variation indicates climate change impact on ecosystem functioning

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