Finite groups with <Emphasis Type="Italic">C</Emphasis>-quasinormal subgroups

Consider some finite group G and a finite subgroup H of G. Say that H is c-quasinormal in G if G has a quasinormal subgroup T such that HT = G and T ∩ H is quasinormal in G. Given a noncyclic Sylow subgroup P of G, we fix some subgroup D such that 1 < |D| < | P| and study the structure of G under the assumption that all subgroups H of P of the same order as D, having no supersolvable supplement in G, are c-quasinormal in G.     

Experimental Study on the Flexural Ductility of BFRP Bar Concrete Beams With Bamboo Fiber and Steel Wire Mesh北大核心CSCD

To study the effects of bamboo fiber and steel wire mesh on the flexural ductility of basalt fiber reinforced polymer（BFRP）bar concrete beams, 7 BFRP bar concrete beams with bamboo fiber and steel wire mesh were tested with different bamboo fiber lengths (0 mm, 30 mm and 45 mm) and different steel wire mesh layout ranges (0, 1/2 maximum bending moment point layout and full beam length layout). The flexural failure tests of the 7 beams were carried out, and the initial crack loads, the crack developments, the ultimate loads and the deformations were detected. The effects of the fiber length and the wire mesh layout range on the crack resistance and the deformation resistance of the specimens were analyzed based on the test data. With the function model, the equivalent yield points of the 7 test beams were obtained, and their ductility coefficients were calculated. The results show that, the addition of bamboo fiber and steel wire mesh increases the cracking loads of BFRP bar concrete beams by 12%~68%, decreases the crack spacings and the crack length development speed, reduces the test beam deformation under the same load, and increases the ductility coefficient by 1.58%~31.75%. © 2023 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

Liquefaction and displacement of saturated sand under vertical vibration loading

In order to investigate the influence of the vertical vibration loading on the liquefaction of saturated sand, one dimensional model for the saturated sand with a vertical vibration is presented based on the two phase continuous media theory. The development of the liquefaction and the liquefaction region are analyzed. It is shown that the vertical vibration loading could induce liquefaction. The rate of the liquefaction increases with the increase of the initial limit strain or initial porosity or amplitude and frequency of loading, and increases with the decrease of the permeability or initial modulus. It is shown also that there is a phase lag in the sand column. When the sand permeability distribution is non-uniform, the pore pressure and the strain will rise sharply where the permeability is the smallest, and fracture might be induced. With the development of liquefaction, the strength of the soil foundation becomes smaller and smaller. In the limiting case, landslides or debris flows could occur. The project supported by the National Natural Science Foundation of China (40025103, 10202024)     

覆盖层地基上面板堆石坝区间优化设计

用区间分析方法研究覆盖层地基上面板堆石坝的断面优化设计，根据该坝型的结构特点和工作条件，提出了合适的优化设计数学模型，探讨了区间优化的求解方法。实例计算表明，方法的收敛性好，计算量小；所得到的设计方案经济合理，安合可靠。     

双向压弯钢筋混凝土柱的非线性分析

在指出现有多弹簧模型存在问题的前提下,结合现有分析剪力墙的多垂直杆单元模型,提出了一种拓展的多垂直杆单元模型,这种模型可适用于各种截面形式的柱、墙肢和梁。另外,本文也提出了考虑刚度下降段的简化方法,最后提供了一个算例,算例结果表明本文模型的合理性。     

A MODEL FOR CONCRETE DURABILITY DEGRADATION IN FREEZE-THAWING CYCLES

Up to now, how to control the durability of concrete structures is still a pending research topic in civil engineering. Owing to the fact that concrete durability can be affected by many non-mechanical factors, it is very difficult to research durability only based on mechanics.However, the phenomenon of failure caused by non-mechanical factors is similar to that caused by loads. As frost durability reflects the comprehensive durability of concrete in a certain sense,the specific failure process is analyzed and a damage model is introduced, which can describe the durability degradation process of concrete in the whole freeze-thawing cycle.     

ANALYSIS MODEL ON GRADUAL CHANGE PRINCIPLE OF EFFECT ZONES OF LAYER FACE FOR ROLLED CONTROL CONCRETE DAM

The effect zones of layer face for RCC (rolled control concrete) dam have gradual change characteristics. Based on the analysis thought of complex material, a model was built to analyze above principle of RCC dam by use of series-wound and shunt-wound connection. Some methods were proposed to determine the instantaneous Young's modulus, delayed Young's modulus and viscosity coefficient of effect zones of layer face. Above models and methods were used to mine the principle of gradual change of key calculation parameters which can response the characteristics of effect zones. The principle of gradual change was described. A model was established to analyze the three-dimensional viscoelastic problem of RCC dam. Above programs were developed. The examples show that the proposed models and methods to determine the key calculation parameters of effect zones can reflect the status of RCC dam accurately.     

冲击载荷作用下钢筋混凝土结构动力响应仿真

运用动态有限元技术对冲击性载荷作用下钢筋混凝土结构的动力响应进行细观结构的仿真分析，建立分离式材料模型，获得射弹在钢筋混凝土中的侵彻深度与弹坑半径，得出钢筋配筋率、配筋方式、配筋位置以及混凝土材料性质等相关因素的影响规律，并针对结果进行分析和讨论，为防护工程设计提供了参考依据。     

基于CSO-SVR的气膜钢筋混凝土储仓主体结构施工成本预测研究

为了较准确的预测气膜钢筋混凝土储仓主体结构施工成本,提出一种鸡群算法(CSO)和支持向量回归机(SVR)结合模型,即CSO-SVR,利用CSO算法对SVR进行寻优得到全局最优解,从而得到具有最佳参数的支持向量回归机模型,通过气膜钢筋混凝土储仓主体结构施工成本数据预测仿真,结果显示:CSO-SVR模型预测精度高于PSO-SVR,GA-SVR,SVR,BPNN等方法,是预测气膜钢筋混凝土储仓主体结构施工成本的有效工具.     

Development and characterization of amphiphilic hydroxyethyl starch derivatives

Novel amphiphilic hydroxyethyl starch derivatives 2,4-bistertbutylphenoxy-[1,3,5] -triazine-6-yl)-hydroxyethyl starch with different degrees of substitution of hydrophilic triazine group and hydrophobic hydroxyethyl were prepared by reacting corn starch with chlorohydrin and 2,4-Ditertbutyl phenoxyl-6-chloro-[1,3,5]-triazine, successively. Their structure was characterized by FTIR, ¹H NMR, and SEM. It exhibits ideal surfacial abilities and compressive strength. The surface tension of the amphiphilic hydroxyethyl starch derivatives (MS = 1.1, DS = 0.026) reached 33.35 mN · m^?1 at the critical aggregation concentration (CAC) at 25°C. The compressive strength of foam concrete was 0.97 MPa when the amount of added starch derivatives (MS = 1.1, DS = 0.026) reached 0.1 wt% of the total weight.