Regional gradient controllability of ultra-slow diffusions involving the Hadamard-Caputo time fractional derivative

This paper investigates the regional gradient controllability for ultra-slow diffusion processes governed by the time fractional diffusion systems with a Hadamard-Caputo time fractional derivative. Some necessary and sufficient conditions on regional gradient exact and approximate controllability are first given and proved in detail. Secondly, we propose an approach on how to calculate the minimum number of $\omega-$strategic actuators. Moreover, the existence, uniqueness and the concrete form of the optimal controller for the system under consideration are presented by employing the Hilbert Uniqueness Method (HUM) among all the admissible ones. Finally, we illustrate our results by an interesting example.Comment: 16 page

Holocene Chronostratigraphy of Dune Fields in Southern Utah: Geomorphic Record of Past Aridity in the Central Colorado Plateau

The southwestern United States is characterized by dry climate, and droughts are common. The region is currently in an extreme drought that began in 2000 CE and has lasted longer than any previous drought in at least 500 years. Models predict greater future climate extremes under human-caused climate change. Understanding of the natural range of climate variability is important to put these changes in context. Sedimentary archives of past sand dune activity can help extend the available instrumental observations (last century) and tree-ring records (last millennium). Sand dunes are landforms that are sensitive to aridity and decreased vegetation cover. They can reactivate and migrate downwind during periods of aridity leaving behind a sediment record of past dune field activity. Research goals were to reconstruct past dune activity the Kanab and San Rafael dune fields in southern Utah. This was accomplished by mapping the dune forms and sampling for age control and sediment character. Modern wind data were compared to the orientation of the older dune forms to determine if wind directions have changed. The Kanab dune field, in southwestern Utah, was found to have been active five times over the last 10,000 yr. The data indicate 1000 yr-long periods of activity separated by similar duration periods of stability. The San Rafael dune field, in east central Utah contained records of seven episodes of eolian activity from late Pleistocene (~17,000 years ago) to the present. Dunes are active today in this dune field with thinner dune deposits and sparser vegetation suggesting greater wind erosion than in the Kanab dune field. Comparing records between the two dune fields indicates three time periods when they were both actively migrating, suggesting regional aridity ~9,500-7,500, 2000-1500 and 1000-500 years ago. Expanding this comparison to existing sand dune records across the Colorado Plateau suggests at least these three periods, and as many as five periods of regional aridity, may have occurred in the last 10,000 years. Wind and geochemical data indicate similar wind and source sediments have been active over the history of the dune fields

Contribution of laser altimetry images to the geomorphology of the Late Holocene inland drift sands of the European Sand Belt

The paper explores the possibilities of applying the analysis of laser altimetry images to Dutch drift sands. All along the European Sand Belt, which stretches from Great Britain to the Ural Mountains, Late Glacial cover sands, river dunes and other ice–age deposits were reactivated as drift sand during the Holocene. New insights were obtained in three aspects of drift–sands geomorphology. First, the variety in forms of drift–sand landscapes is often described as chaotic. Laser altimetry images show that complex clusters are formed elongated in the direction of the prevailing SW wind and consisting of three zones which correspond to the successive aspects of the aeolian process: deflation, transport and deposition (dune formation). In densely populated areas, this structure has been ruined by human activities. Second, contrary to common belief, the drift–sand cells expanded against the prevailing SW wind whereas the characteristic comb dunes at the opposite NE edge remained fixed by vegetation. Third, the authors questioned the view that drift sands are due to anthropogenic activities. The origin of drift sands can best be explained by the climate with violent storms in the first part of the past millennium

A synthesis of sand seas throughout the world

There are no author-identified significant results in this report

Application of the Feshbach-resonance management to a tightly confined Bose-Einstein condensate

We study suppression of the collapse and stabilization of matter-wave solitons by means of time-periodic modulation of the effective nonlinearity, using the nonpolynomial Schroedinger equation (NPSE) for BEC trapped in a tight cigar-shaped potential. By means of systematic simulations, a stability region is identified in the plane of the modulation amplitude and frequency. In the low-frequency regime, solitons feature chaotic evolution, although they remain robust objects.Comment: Physical Review A, in pres