盾构隧道近距离穿越浦江饭店施工保护技术

浦江饭店是上海外滩通道工程施工过程中的重要保护节点,普通的灌注隔离桩保护技术因为其施工时引起的沉降量大等原因已不能满足该工程的需要.为此在试验和监测的基础上,提出一种外套管内螺旋取土的隔离桩施工方法,简称FCEC工法,并比较了该工法与普通灌注隔离桩的优缺点.FCEC工法施工过程中对土体的扰动小,成桩时带土量少.混凝土浇注充盈系数平均达到1.07,并且成桩后对桩周土体具有挤压效应,这对有效控制沉降有十分重要的作用.FCEC工法在控制不均匀沉降和整体最大沉降方面比普通灌注桩有很大的提高,为彻底满足本工程在总体最大沉降控制的苛刻要求,在桩间辅助水泥浆与水玻璃双液浆注浆,有效控制了该工程的整体最大沉降.     

Large eddy simulation of dense two-phase flows: Comment on DEM-LES study of 3-D bubbling fluidized bed with immersed tubes

In a recent paper, Gui et al. (2008. DEM-LES study of 3-D bubbling fluidized bed with immersed tubes. Chemical Engineering Science 63, 3654–3663) reported the results of numerical simulations of a bubbling fluidized bed containing internal tubes using discrete element model (DEM) coupled to a large eddy simulation (LES). We comment on the correctness of the numerical set-up regarding the use of LES as well as the worthiness of using a turbulence model for the case of dense two-phase flows.     

Genetic Differentiation between Natural and Hatchery Stocks of Japanese Scallop (Mizuhopecten yessoensis) as Revealed by AFLP Analysis

Japanese scallop (Mizuhopecten yessoensis) is a cold-tolerant bivalve that was introduced to China for aquaculture in 1982. In this study, amplified fragment length polymorphism (AFLP) markers were used to investigate levels of genetic diversity within M. yessoensis cultured stocks and compare them with wild populations. Six pairs of primer combinations generated 368 loci among 332 individuals, in four cultured and three wild populations. High polymorphism at AFLP markers was found within both cultured and wild M. yessoensis populations. The percentage of polymorphic loci ranged from 61.04% to 72.08%, while the mean heterozygosity ranged from 0.2116 to 0.2596. Compared with wild populations, the four hatchery populations showed significant genetic changes, such as lower expected heterozygosity and percentage of polymorphic loci, and smaller frequency of private alleles, all indicative of a reduction in genetic diversity. Some genetic structures were associated with the geographical distribution of samples; with all samples from Dalian and Japan being closely related, while the population from Russia fell into a distinct clade in the phylogenetic analysis. The genetic information derived from this study indicated that intentional or accidental release of selected Japanese scallops into natural sea areas might result in disturbance of local gene pools and loss of genetic variability. We recommend monitoring the genetic variability of selected hatchery populations to enhance conservation of natural Japanese scallop resources.     

Assessment of the effects of rice husk ash particle size on strength,water permeability and workability of binary blended concrete

This study develops the compressive strength, water permeability and workability of concrete by partial replacement of cement with agro-waste rice husk ash. Two types of rice husk ash with average particle size of 5 micron (ultra fine particles) and 95 micron and with four different contents of 5%, 10%, 15% and 20% by weight were used. Replacement of cement up to maximum of 15% and 20% respectively by 95 and 5 μm rice husk ash, produces concrete with improved strength. However, the ultimate strength of concrete was gained at 10% of cement replacement by ultra fine rice husk ash particles. Also the percentage, velocity and coefficient of water absorption significantly decreased with 10% cement replacement by ultra fine rice husk ash. Moreover, the workability of fresh concrete was remarkably improved by increasing the content of rice husk ash especially in the case of coarser size. It is concluded that partial replacement of cement with rice husk ash improves the compressive strength and workability of concrete and decreases its water permeability. In addition, decreasing rice husk ash average particle size provides a positive effect on the compressive strength and water permeability of hardened concrete but indicates adverse effect on the workability of fresh concrete.     

土岩组合地层基坑工程变形监测分析

介绍了青岛岩石地区土岩组合的一个典型超深基坑工程案例。鉴于地层的特殊性以及基坑开挖深度,采用吊脚桩加锚索支护体系,局部放坡结合钢管桩预支护。通过有限元数值分析结果与现场实测数据对比表明:在上覆土层较薄的岩石地区,围护结构的变形主要集中在土层部分。采用上述支护体系可以在有效的控制基坑及周围环境变形的同时,大大地减少工程造价,以期为今后类似工程提供有益的借鉴。     

钢筋混凝土结构设计原理课程教学探讨

钢筋混凝土结构设计原理是港口航道工程专业的一门专业基础课,与工程实际联系紧密,对培养学生掌握基本理论、专业技能和解决实际工程问题的能力有着重要作用。教师在教学中不仅要传授混凝土结构的基本原理,更重要的是通过课程教学培养学生的工程能力,包括研究能力、实践能力、文字表达能力等。文章从教学总体设计、教学及考核方法的改革、重视实践教学过程的管理、实验和规范的应用等方面进行了深入探讨,并提出了合理化建议。     

Hardware design of motion data decoding process for H.264/AVC

In H.264/AVC, motion data can be basically derived by the following two schemes: one is a typical spatial prediction scheme based on the DPCM and the other is a sophisticated spatiotemporal prediction scheme for the skipped motion data, formally referred to as a direct mode. We verified through instruction level profiling that when these schemes are combined with various H.264/AVC coding techniques, the computational burden to derive the motion data could be considerably aggravated. Specifically, its computational complexity amounts to maximally 55% of that of the overall syntax parsing process. In this paper, we aim at an efficient hardware design of the motion data decoding process for H.264/AVC, for which all the key design considerations are addressed in detail and respective rational answers are presented. As comparing the resulting hardware design with the processor-based solution, its effectiveness was clearly demonstrated. The proposed design was implemented with 43.2 K logic gates and three on-chip memories of 3584 bits using Samsung Semiconductor’s Standard Cell Library in 65 nm L6LP process technology (SS65LP), and was capable of operating the H.264/AVC high-profile video bitstream of 1080p@60fps at 100 MHz consuming 843 μW.     

多孔射流式通风的流场特性分析

为了分析多孔射流风机作用下风场的流场特性,文中采用CFD方法,对多孔射流式风场模型内部流场进行了数值模拟,对比分析了不同喷嘴数量及排布方式对流场性能的影响,并引入涡动力学理论,分析了流场内涡结构的分布发展规律及其对流体掺混的影响。结果表明：喷嘴的数量及排布方式对流场性能有显著影响,外围喷嘴会对中心喷嘴的流动起到限制作用;流向涡对流体掺混效果的作用比展向涡大,在涡量一定的情况下,流向涡尺度越大、衰减越快,流体间的混合效果越好,流场稳定性越高。流场内速度及涡动力学分布表明,流场稳定性随着喷嘴数量的增加而显著提高,因此在保证经济性的前提下应尽量采用数量多的喷嘴排布方式。     

FDM制备晶格点阵结构体的一种卡扣式打印方法的研究

熔融沉积技术（Fused deposition modeling,FDM）打印晶格点阵结构时,存在着打印件机械性能差、支撑材料难去除的问题。针对这些问题,本文将晶格结构体分解成数个二维模型,通过FDM进行分体打印然后利用卡扣配合重新组装。利用这种分体打印工艺深入探索了BCC、BCC-Z、F2CC和F2CC-Z这4种典型结构类型的晶格体结构的表面形貌和机械性能,并与传统一体式打印进行对比。发现该卡扣式分体方法实现了打印物体表面质量的改善、打印时间和打印材料的节省以及抗压性能的提升。该研究为实现3D打印制备晶格结构体提供了一种途径,并为选择合适的晶格类型提供了参考。     

溴系阻燃剂BN451的合成及其在聚丙烯中的应用

通过先溴化后酰亚胺成环法合成了阻燃剂BN451(N,N'-1,2-乙烷-双[5,6-二溴降冰片烷-2,3-二酰亚胺]),红外光谱图表明存在目标产品的特征吸收峰。讨论了在降冰片-5-烯-2,3-二酸酐溴化过程中反应温度、N,N-二甲基甲酰胺、乙二胺用量对产率的影响。在较佳反应条件下,即反应温度40℃,降冰片-5-烯-2,3-二酸酐13g,N,N-二甲基甲酰胺11mL,乙二胺13mL时,反应收率为70%。将阻燃剂BN451按不同比例与聚丙烯混合,探索了阻燃聚丙烯阻燃性和拉伸强度随阻燃剂含量的变化规律。