Spatial-Temporal Pattern Analysis of Land Use and Water Yield in Water Source Region of Middle Route of South-to-North Water Transfer Project Based on Google Earth Engine

The water source area of the middle route of the South-to-North Water Diversion Project is an important water conservation and ecological protection area in China. Based on remote sensing data, this paper analyzed the evolution process of land use/cover change in water source region in the past 35 years. Then, based on the InVEST model, the spatial-temporal patterns of water yield in the water source region were calculated with land use cover, meteorology and soil data as inputs. The impacts of climate factors such as precipitation and temperature and land use change on water yield were discussed, and the responses of water yield to these two changes were also discussed. The results show that from 1985 to 2020, the average water yield depth in the middle route of the South-to-North Water Diversion Project increases first and then decreases, from 615 mm in 1985 to 738 mm in 2000, and then decreases to 521 mm in 2020. The spatial heterogeneity of the water-producing capacity is obvious. The high value of the water-producing capacity is concentrated in the Daba Mountain area in the south, while the low values are concentrated in the Hanzhong Basin, Ankang Basin and the eastern plain area. The spatial pattern of water producing depth has no obvious change. The average water yield depth of forest, grassland and shrub in the region was the largest, and forest and cultivated land were the main contributors to the total water yield of the region, providing 82% and 14% of the total water yield in 2020. Precipitation has a significant effect on water yield, while land use/cover change has a small effect on water yield

Simulation of electrical properties of InxAl1- XN/AlN/GaN high electron mobility transistor structure

Electrical properties of InxAl1- xN/AlN/GaN structure are investigated by solving coupled Schro¨dinger and Poisson equations self-consistently. The variations in internal polarizations in In xAl1- xN with indium contents are studied and the total polarization is zero when the indium content is0.41. Our calculations show that the two-dimensional electron gas(2DEG) sheet density will decrease with increasing indium content. There is a critical thickness for AlN. The2DEG sheet density will increase with InxAl1- xN thickness when the AlN thickness is less than the critical value. However, once the AlN thickness becomes greater than the critical value, the2DEG sheet density will decrease with increasing barrier thickness. The critical value of AlN is2.8 nm for the lattice-matched In0.18Al0.82N/AlN/GaN structure. Our calculations also show that the critical value decreases with increasing indium content.?2011 Chinese Institute of Electronics

The influence of the1st AlN and the2nd GaN layers on properties of AlGaN/2nd AlN/2nd GaN/1st AlN/1st GaN structure

This is a theoretical study of the1st AlN interlayer and the2nd GaN layer on properties of the Al0.3Ga0.7N/2nd AlN/2nd GaN/1st AlN/1st GaN HEMT structure by self-consistently solving coupled Schro¨dinger and Poisson equations. Our calculation shows that by increasing the1st AlN thickness from1.0 nm to3.0 nm, the2DEG, which is originally confined totally in the2nd channel, gradually decreases, begins to turn up and eventually concentrates in the1st one. The total2DEG(2DEG in both channels) sheet density increases nearly linearly with the increasing1st AlN thickness. And the slope of the potential profile of the AlGaN changes with the1st AlN thickness, causing the unusual dependence of the total2DEG sheet density on the thickness of the AlGaN barrier. The variations of2DEG distribution, the total2DEG sheet density and the conduction band profiles as a function of the2nd GaN thickness also have been discussed. Their physical mechanisms have been investigated on the basis of the surface state theory. And the confinement of2DEG can be further enhanced by the double-AlN interlayer, compared with the InGaN back-barrier.? Springer-Verlag2011

Analysis of transconductance characteristic of AlGaN/GaN HEMTs with graded AlGaN layer

A theoretical study of transconductance characteristics (gm − Vgs profile) of AlGaN/GaN high electron mobility transistors (HEMTs) with a graded AlGaN layer is given in this paper. The calculations were made using a self-consistent solution of the Schrödinger-Poisson equations and an AlGaN/GaN HEMTs numerical device model. Transconductance characteristics of the devices are discussed while the thickness and Al composition of the graded AlGaN layer are optimized. It is found that graded AlGaN layer structure can tailor device’s gm − Vgs profile by improving polar optical phonon mobility and interface roughness mobility. Good agreement is obtained between the theoretical calculations and experimental measurements over the full range of applied gate bias

The concurrent disturbance of dynamic functional and structural brain connectome in major depressive disorder: the prefronto-insular pathway

Background: Robust evidence has shown that abnormal function networks, particularly the salience network (SN), are observed in depressed patients. Although white matter structural connectivity may predict time-varying functional connectivity, including symptom phenotype, in psychiatric disorders, there is still a gap in elucidating the concurrent dynamic functional and structural connectivity profiles of the SN in depressed patients. Methods: We measured static and dynamic functional connectivity (FC) of the SN using resting-state fMRI BOLD time series in 76 subjects (21 with major depressive disorder (MDD), 27 with bipolar depression (BD), and 28 healthy controls (HC)). Hamilton Depression Scale total score was used to measure depression severity. Furthermore, we investigated the concurrent structural connectivity using diffusion kurtosis imaging (DKI)-based tractography. Results: Our findings suggested that in the presence of MDD, both structural and dynamic (but not static) FC were reduced in the SN, particularly affecting the left prefronto-insular pathways (L.aPFC-L.insula). MDD patients showed decreased connectivity variability within the SN compared with HC. The aberrant dynamic FC in the prefronto-insular pathways of the SN related to severity of depressive symptoms in MDD. Furthermore, compared with BD patients, those with MDD showed significantly decreased dynamic FC in the left prefronto-parietal system (L.aPFC-lateral parietal cortex). Limitations: The generalizability of our findings is, to some extent, constrained by the small sample size. Conclusions: The integrity of SN connectivity, particularly the prefronto-insular pathway, appears to be a crucial signature of MDD. The perturbed dynamic interaction of SN with prefrontal regions may underlie the clinical severity in depressed patients