山东大学新校区环境设计

从空间分析的角度介绍山东大学新校区景观规划设计的构思,引申出对校园空间格局的探讨,为今后更好地从人文主义出发,创造宜人化的生活环境尺度提供借鉴.     

Comparative experimental study of hot-rolled and cold-formed rectangular hollow sections

Square and rectangular hollow sections are generally produced either by hot-rolling or cold-forming. Cross-sections of nominally similar geometries, but from the two different production routes may vary significantly in terms of their general material properties, geometric imperfections, residual stresses, corner geometry and material response and general structural behaviour and load-carrying capacity. In this paper, an experimental programme comprising tensile coupon tests on flat and corner material, measurements of geometric imperfections and residual stresses, stub column tests and simple and continuous beam tests is described. The results of the tests have been combined with other available test data on square and rectangular hollow sections and analysed. Enhancements in yield and ultimate strengths, beyond those quoted in the respective mill certificates, were observed in the corner regions of the cold-formed sections—these are caused by cold-working of the material during production, and predictive models have been proposed. Initial geometric imperfections were generally low in both the hot-rolled and cold-formed sections, with larger imperfections emerging towards the ends of the cold-formed members—these were attributed largely to the release of through thickness residual stresses, which were themselves quantified. The results of the stub column and simple bending tests were used to assess the current slenderness limits given in Eurocode 3, including the possible dependency on production route, whilst the results of the continuous beam tests were evaluated with reference to the assumptions typically made in plastic analysis and design. Current slenderness limits, assessed on the basis of bending tests, appear appropriate, though the Class 3 slenderness limit, assessed on the basis of compression tests, seems optimistic. Of the features investigated, strain hardening characteristics of the material were identified as being primarily responsible for the differences in structural behaviour between hot-rolled and cold-formed sections.     

Characterization of effluent water qualities from satellite membrane bioreactor facilities

Membrane bioreactors (MBRs) are often a preferred treatment technology for satellite water recycling facilities since they produce consistent effluent water quality with a small footprint and require little or no supervision. While the water quality produced from centralized MBRs has been widely reported, there is no study in the literature addressing the effluent quality from a broad range of satellite facilities. Thus, a study was conducted to characterize effluent water qualities produced by satellite MBRs with respect to organic, inorganic, physical and microbial parameters. Results from sampling 38 satellite MBR facilities across the U.S. demonstrated that 90% of these facilities produced nitrified (NH₄-N <0.4 mg/L-N) effluents that have low organic carbon (TOC <8.1 mg/L), turbidities of <0.7 NTU, total coliform bacterial concentrations <100 CFU/100 mL and indigenous MS-2 bacteriophage concentrations <21 PFU/100 mL. Multiple sampling events from selected satellite facilities demonstrated process capability to consistently produce effluent with low concentrations of ammonia, TOC and turbidity. UV-254 transmittance values varied substantially during multiple sampling events indicating a need for attention in designing downstream UV disinfection systems. Although enteroviruses, rotaviruses and hepatitis A viruses (HAV) were absent in all samples, adenoviruses were detected in effluents of all nine MBR facilities sampled. The presence of Giardia cysts in filtrate samples of two of nine MBR facilities sampled demonstrated the need for an appropriate disinfection process at these facilities.     

循环荷载作用下岩石疲劳变形及特性试验研究

通过开展恒定加卸载速率,不同偏应力条件下的循环加卸载试验,研究了轴向应变、径向应变以及体积应该随循环次数的演化过程,得到了在不同偏应力条件下岩石的平均变形模量随循环次数与偏应力的变化关系,进而分析了循环荷载作用下岩石疲劳变形及特性。研究结果表明：（1）偏应力在50MPa之前,轴向应变、径向应变、体积应变以及变形模量随着循环次数的变化基本稳定,反之,表现出发散的趋势;（2）偏应力在80MPa作用下的平均变形模量较1IOMPa作用下的大,这是岩石内部裂隙增加和扩张的结果;（3）在不同偏应力条件下,平均变形模量随着偏应力的增大逐渐增大且趋于收敛。     

桁架尺寸、几何形状和拓扑优化的力法和遗传算法

结合能量和力法进行桁架重量的最小化,为此,采用遗传算法作为优化工具。提出的主要思想是减少输入变量。在采用遗传算法进行结构优化时,力法的引入非常有意义。该方法不需要求逆矩阵,只需在遗传算法中加入有限的变量,变量的个数等于结构超静定次数。通过几种不同类型的优化案例,验证了当前方法的有效性,并对不同优化技术的结果进行了比较。     

Study of the behavior of mechanically stabilized earth (MSE) walls subjected to differential settlements

The limit equilibrium (LE) analysis has been used to design MSE walls. Presumably, the deflection of MSE walls can be limited to an acceptable range by ensuring sufficient factors of safety (FOSs) for both external and internal stabilities. However, unexpected ground movements, such as movements induced by excavations, volume changes of expansive soils, collapse of sinkholes, and consolidations of underlying soils, can induce excessive differential settlements that may influence both the stability and the serviceability of MSE walls. In this study, a numerical model, which was calibrated by triaxial tests and further by a specially-designed MSE wall tests, investigated the behavior of an MSE wall as well as the influence of various factors on the performance of the MSE wall when the wall facing settled relatively to the reinforced zone. The numerical results showed that the differential settlement would cause substantial vertical and horizontal movements for the MSE wall, as well as an increase in lateral earth pressure and geosynthetic reinforcement strain. The maximum horizontal movement and increase of the lateral earth pressure occurred at about 1.0 m above the toe. The differential settlement resulted in a critical plane that coincided with the plane of 45°+?/2. The maximum increase of the strain for each geogrid layer occurred in that plane, and the bottom layer had the greatest strain increase among all layers of reinforcement. The study further indicated that the surcharge, backfill friction angle, tensile stiffness of geogrid, reinforcement length and MSE wall height had noticeable influences on horizontal and vertical movements, and strain in geosynthetics. According to the results, the MSE wall that had a higher factor of safety would have less movements and geosynthetic strain increase. In contrast, only the friction angle, tensile stiffness and MSE wall height showed some degree of influence on the lateral earth pressure due to differential settlements.     

Identification of bearing load by three section strain gauge method: Theoretical and experimental research

Reasonable bearing load distribution is important for the safe and reliable operation of rotating machinery. However, it is difficult to measure bearing load in field. This paper puts forward a bearing load identification method based on the measured three section strain values. Shaft is divided into several sections at strain gauge locations. The force and moment equilibrium equations are set up and assembled to form bearing load solving equations. This method can reduce the modeling error, especially for the machines with irregular rotating parts. It can also be applied for the entire shaft system bearing load distribution study with high accuracy and fault tolerant. Test was done on a rotor-bearing system rig. Bearing load distribution in different shaft alignment states is identified and analyzed. Test results show that the bearing load distribution varies sensitively and linearity to the change of bearing elevation. Further research shows that the accuracy of the method depends on the strain gauge locations. It would be best to place the strain gauge at location where the bending moment is sensitive to the change of bearing load. Moreover, mounting the strain gauge further from the bearing reduces the relative error due to the exact reaction point location is not known, which influences the accuracy of beading moment arm from the strain gauge location to the reaction point.     

Vero细胞森林脑炎疫苗毒种的选育及其生物学特性检测

目的选育Vero细胞森林脑炎疫苗适应毒种。方法将森林脑炎疫苗鼠脑病毒“森张”株在Vero细胞上连续传代适应,并对不同代次收获的病毒液的病毒滴度、免疫原性、稳定性等进行检测。结果“森张”株病毒在Vero细胞上传代适应后,病毒滴度达8·5LgLD50/ml;免疫血清中和抗体效价高于1∶20,其它检测项目均符合疫苗生产用毒种的要求。结论Vero细胞适应的“森张”株毒种的初步特性显示可作为制备Vero细胞森林脑炎疫苗用毒种。     

Positive Strain Rate Sensitivity and Deformation Behavior of a Fe-29Mn-3Al-3Si TWIP Steel

The Fe-29Mn-3Al-3Si twin-induced plasticity (TWIP) steel is used to conduct quasi-static compression and dynamic impact deformation with strain rates ranging from 8.3 × 10^-4 to 3800 s^-1. The microstructures and properties of deformed samples under different strain rates were investigated comparatively. These results show that positive strain rate sensitivity was observed with the increase in strain rates and that there was a significant difference in strain rate sensitivity factor (ṁ) between quasi-static compression (ṁ = 0.029) and dynamic impact deformation (ṁ = 0.190). Compared to the quasi-static compression, the dynamic impact deformation exhibited higher yield strength. Microstructural examination reveals that the primary twins were frequently found during the quasi-static compression process, and the secondary twins were rarely observed. However, the secondary and multi-fold deformation twins were florescent in the dynamic impact samples. At the initial stage of dynamic impact deformation, partial dislocations and staking faults on multiple conjugate {111} planes were simultaneously activated and produced a large number of Lomer-Cottrell dislocations, resulting in a large increase in yield strength during dynamic impact.