宁夏山区建设中的岩土工程问题

近年来 ,随着工业和旅游业的发展 ,在宁夏 ,特别是宁南低山黄土丘陵区及银川西侧的贺兰山区 ,一些不适于建筑的山坡、谷地 ,也成为建筑场地 ,随着也带来一系列与环境保护、岩土工程有密切关系的问题 ,如不慎重对待 ,妥善解决 ,必将产生十分严重的后果 ,阻碍山区建设的进一步发展。     

Stagnation-point flow of a viscoelastic fluid towards a stretching surface

An analysis is made of the steady two-dimensional stagnation-point flow of an incompressible viscoelastic fluid over a flat deformable surface when the surface is stretched in its own plane with a velocity proportional to the distance from the stagnation-point. It is shown that for a viscoelastic fluid of short memory (obeying Walters’ B′ model), a boundary layer is formed when the stretching velocity of the surface is less than the inviscid free-stream velocity and velocity at a point increases with increase in the elasticity of the fluid. On the other hand, an inverted boundary layer is formed when the surface stretching velocity exceeds the velocity of the free stream and the velocity decreases with increase in the elasticity of the fluid. A novel result of the analysis is that the flow near the stretching surface is that corresponding to an inviscid stagnation-point flow when the surface stretching velocity is equal to the velocity of the free stream. Temperature distribution in the boundary layer is found when the surface is held at constant temperature and surface heat flux is determined. It is found that temperature at a point decreases with increase in the elasticity of the fluid.     

Extending Circle Mappings to the Annulus

We show that any monotone degree one C mapping of the circle can be realized as the induced mapping on the boundary by a C area preserving diffeomorphism of the open annulus. The circle mapping may have critical points, allowing the possibility of Denjoy behavior on the boundary.     

Removal of carbonyl sulfide from CO2 stream using AgNO3-modified NaZSM-5

Removal of carbonyl sulfide (COS) from CO₂ stream is significant for the production and utilization of food grade CO₂. This study investigates the adsorption performance of Ag/NaZSM-5 as adsorbent prepared by incipient wetness impregnation for the removal of COS from a CO₂ stream in a fixed-bed adsorption apparatus. Effects of various conditions on the preparation of adsorbent, adsorption and desorption were intensively examined. The results revealed that COS can be removed to below 1×10^?9 from a CO₂ stream (1000 ppm COS/CO₂) using Ag/NaZSM-5 (10 wt% AgNO₃) with an adsorption capacity of 12.86 mg-g^?1. The adsorbent can be fully regenerated using hot air at 450 °C. The adsorption ability remained stable even after eight cycles of regeneration.     

Errata and addendum to “On the prime geodesic theorem for hyperbolic ‐manifolds” Math. Nachr. 291 (2018), no. 14–15, 2160–2167

We correct the exponent in the error term of the prime geodesic theorem for hyperbolic 3‐manifolds 1 and in Park's theorem for higher dimensions [ 3 , 2 ].     

Radical of submodules and symmetric algebra

A prime ideal of the symmetric algebra of an R-module N is associated to every prime submodule M ?N and this assignment is then used to obtain a new characterization of the radical of a submodule. Several applications of these results are also included.     

On functional identities in left ideals of prime rings

In the present paper we describe surjective Lie and Jordan maps onto left ideals of prime noncommutative rings. Further, we describe bijective linear maps of left ideals of centrally closed prime algebras preserving commutativity.     

Synthesis of 2,2′-bipyrrole-5-carboxaldehydes and their application in the synthesis of B-ring functionalized prodiginines and tambjamines

Facile, versatile, and cost-effective synthetic routes for the preparation of a range of new 3-alkyl-, 4-alkyl-, 3,4-dialkyl-, and 3-halo-4-alkyl-2,2′-bipyrrole-5-carboxaldehydes have been developed. These 2,2′-bipyrrole-5-carboxaldehydes offer interesting potential as building blocks for making bioactive natural and unnatural products, as demonstrated by the synthesis of B-ring functionalized prodiginines (PGs) and tambjamines.