Search

Wind is one of the major processes modifying the land surface in the Hami Basin, as evidenced by wind deflation gravel lags, yardangs, and gravel mantled eolian ripples. We report erosion rates for the Hami Basin using cosmogenic 10Be measurements. Bedrock erosion rates average 0.121 ± 0.0293 mm yr−1, which is similar to those of other wind‐eroded arid basins in East Asia, but is anomalously low when modern near‐surface wind speeds are considered. We posit that interglacial periods experienced lower erosion rates than glacial periods, and that the Hami Basin was likely once a larger dust producer than at present, with Pleistocene dust emissions driven by the eolian deflation of alluvial terrace deposits as well as bedrock weathering and abrasion. Wind erosion and dust production in the Hami Basin was largely regulated by the synoptically controlled spatial‐temporal distribution of precipitation and subsequent landscape evolution since at least the late Pleistocene. Plain Language Summary: The Hami Basin in Xinjiang, China is in the core of the >3 × 106 km2 arid to hyperarid dust generating corridor of the eastern Eurasian continental interior. Quantifying the wind abrasion of bedrock on long timescales, while challenging, is necessary to understand landscape evolution. Based on cosmogenic 10Be measurements of wind eroded bedrock features (i.e., yardangs) in the Hami Basin, we provide the first quantitative evaluation of bedrock erosion in the stony Hami Basin over the last ∼20 thousand years. Incorporating previous work with our erosion rates, the results indicate that wind erosion rates are lower now than over multiple previous glacial‐interglacial cycles in the Hami Basin. Key Points: Wind erosion rates in the Hami Basin were determined to be ∼0.121 mm yr−1 for the last ∼11–23 ky using cosmogenic 10Be measurementsInterglacial periods likely experienced lower erosion rates than glacial periods due to changes in atmospheric conditionsWind erosion and dust production were regulated by climate and landscape evolution since the late Pleistocene in the Hami Basin [ABSTRACT FROM AUTHOR]

Summary This paper proposes a high‐power solid‐state power combining frequency multiplier source based on a waveguide magic‐T divider. The magic‐T has the merits of high isolation and reliability compared to conventional Y/T junction power dividers and wider bandwidth compared to 3 dB couplers. In the waveguide magic‐T, a two‐stage cuboid ridge is employed to reduce the difference‐port reflection and act as a matching element for the improved isolation port. Furthermore, two bent waveguides are connected with the output port of the magic‐T, which can achieve phase congruence. The reliability of the solid‐state power combining multiplier can be enhanced by this low‐loss, high‐isolation power divider. Moreover, the divider also facilitates the realization of a high‐power frequency multiplier. Measured results show that the multiplier has a maximum output power of 90.3 mW at 178 GHz with an input power of 448 mW. [ABSTRACT FROM AUTHOR]

In this paper, a grey prediction model group is employed to quantitatively study the impact of COVID‐19 on natural gas consumption in Chongqing, China. First, a grey prediction model group suitable for the prediction of Chongqing's natural gas consumption is introduced, which consists of GM(1,1), TWGM(1,1), and the newly‐developed ODGM(1,1). Then, the model group is constructed to predict Chongqing's natural gas consumption in 2020. Finally, compare the predicted results of the model group with the actual consumption and quantitatively analyze the impact of the epidemic on natural gas in Chongqing. It is found that the impact of the epidemic on the consumption of natural gas in the first quarter of the year is very small, but relatively bigger in the second and third quarters. The study is of positive significance to maintain the supply and demand balance of natural gas consumption in Chongqing in the background of COVID‐19; and it enriches and develops the theoretical system of grey prediction models. [ABSTRACT FROM AUTHOR]

Dust plays an important role in climate, and while our current representation of dust production includes shifts in vegetation, soil moisture, and ice cover, it does not account for the role of landscape evolution. Here, we use the Weather Research and Forecasting model coupled to an aerosol chemistry model to quantify the effects of arid landscape evolution on boundary layer conditions, dust production, and radiative properties in the Hami Basin, China, a dynamic stony desert in eastern Asia. Relative to today, altered surface roughness, sediment erodibility, and albedo combine to produce up to a ~44% increase in wind speeds (mean ≈ 15%), up to a ~59% increase in dust loading (mean ≈ 30%), and up to a ~4.4 W m−2 increase in downwelling radiation (mean ≈ 2.4 W m−2) over the Hami Basin. Our modeling results, along with geomorphological data for the western Gobi Desert, provide evidence that stony deserts acted as important Plio‐Pleistocene dust sources. Plain Language Summary: Dust from the breakdown of rocks and minerals plays an important role in Earth's atmosphere by absorbing or scattering incoming solar radiation, and by seeding clouds. Once deposited, iron‐rich dust can fertilize surface ocean waters and terrestrial soils for the growth of organisms, making dust important in the global carbon cycle. Because of its role in modifying Earth's climate, we must accurately understand ancient dust production. To test the hypothesis that past changes in dust production impacted climate, we altered the surface properties of the western Gobi Desert, a location that had a very different landscape thousands to millions of years ago, and simulated changes in wind and dust using a regional climate model. We found that this area would have experienced increased wind speeds by up to ~40%, increased dust loading by up to ~60%, and substantially altered incoming solar radiation in response to land surface evolution. Key Points: In arid regions, consideration of landscape evolution is necessary to accurately reconstruct dust production and regional climateWe use a regional climate model to quantify the effect of arid landscape evolution on dust production in the Hami Basin, ChinaRepresentative Plio‐Pleistocene surface conditions lead to enhanced winds and dust production in the Hami Basin relative to today [ABSTRACT FROM AUTHOR]

This study presents a design of a tri-band dual polarisation common aperture feed horn used for the radiometer. The proposed feeding system is made up of a corrugated horn, an orthomode transducer (OMT) and two pairs of a high-pass filter (HPF) and a band-pass filter (BPF). The broadband profiled corrugated horn loaded with teeth (rings) is adopted as the feed of the radiometer. Wideband finline OMT is developed to realise a bandwidth ratio in excess of 2:1. Two different HPFs and BPFs are employed to block and pass waves of different frequencies. The feeding structure is then simulated, fabricated and tested. The measured results show that the radiation patterns possess good symmetry at all three working frequencies of interest (18.7, 23.8 and 37 GHz). Furthermore, the cross-polarisation levels are below -23 dB and voltage standing-wave ratios are lower than 1.5 throughout all working bands. [ABSTRACT FROM AUTHOR]