连铸坯中缩敏感系数的研究

连铸坯内部中心缩松、缩孔是影响铸坯内部质量的主要缺陷之一.本文综合运用数值模拟、实验研究、数学推导等手段,提出了描述连铸坯中缩缺陷形成可能性大小的连铸坯中缩敏感系数.并以中缩敏感系数为桥梁,建立了工艺因素与中缩缺陷的关系,为进一步实现连铸工艺的计算机优化奠定了基础.     

Modelling bacterial water quality in streams draining pastoral land

A model has been developed to predict concentrations of the faecal bacteria indicator E. coli in streams draining grazed hill-country in New Zealand. The long-term aim of the modelling is to assess effects of land management upon faecal contamination and, in the short term, to provide a framework for field-based research. A daily record of grazing livestock is used to estimate E. coli inputs to a catchment, and transport of bacteria to the stream network is simulated within surface and subsurface flows. Deposition of E. coli directly to streams is incorporated where cattle have access to them, and areas of permanent saturation ('seepage zones') are also represented. Bacteria are routed down the stream network and in-stream processes of deposition and entrainment are simulated. Die-off, both on land and in water, is simulated as a function of temperature and solar radiation. The model broadly reproduces observed E. coli concentrations in a hill-country catchment grazed by sheep and beef cattle, although uncertainty exists with a number of the processes represented. The model is sensitive to the distance over which surface runoff delivers bacteria to a stream and the amount of excretion direct to streams and onto seepage zones. Scenario analysis suggests that riparian buffer strips may improve bacterial water quality both by eliminating livestock defaecation in and near streams, and by trapping of bacteria by the riparian vegetation.     

稀土La改性铁基非晶带材组织结构与软磁性能研究

主要研究掺杂了不同含量稀土La后的铁基非晶带材Fe73.5Cu1Nb3Si13.5B9非晶带材组织结构与软磁性能.结果表明,随着稀土La掺杂含量的增加,Fe73.5Cu1Nb3Si13.5B9非晶带材的Fe-Si相的析出温度下降,而Fe-B相的析出温度则升高,一方面,非晶的热稳定性下降,另一方面,有利于控制Fe73.5...     

预应力钢带加固混凝土梁斜截面开裂荷载及抗剪承载能力分析

预应力钢带加固钢筋混凝土梁能有效提高梁斜裂缝开裂荷载和斜截面抗剪承载能力。根据试验研究结果,首先分析预应力钢带加固混凝土梁斜截面破坏机理,并考虑预应力度、钢带应变不均匀系数对梁抗剪承载力的影响,并利用桁架模型推导了预应力钢带加固钢筋混凝土梁的抗剪承载力设计算式和实用计算式,同时进一步对预应力钢带加固钢筋混凝土梁应力状态进行计算分析,提出预应力钢带加固混凝土梁斜截面开裂荷载的计算公式。经与试验结果进行对比分析,所提出斜截面承载能力和开裂荷载的两套算式的计算结果均与试验结果吻合较好。     

刨切微薄竹用竹集成方材胶合工艺的研究

总结了用竹片胶合竹集成方材刨切微薄竹常见的三种工艺。选择其中之一,对采用两种不同胶粘剂胶合的竹集成方村的胶合性能进行了对比研究,胶粘剂B的综合性能优于胶粘剂A;还研究了胶粘剂B的热压时间以及固化剂用量对竹层积极胶合强度的影响;并对竹层积极在厚度方向上的胶合工艺进行了研究。     

乳腺粗针穿刺活检组织条数目对活检准确率的影响

目的探讨乳腺粗针穿刺活检所取组织条数目与穿刺活检准确率之间的关系。方法收集2008年4月至2010年3月间经乳腺钼铑双靶X线摄影检查确定需要进行数字化三维立体定位穿刺活检的病例300例,根据就诊时间顺序按序贯试验分为A、B、C 3组,每组100例。在穿刺时A、B、C组病例每个病灶各取组织条2、3和4条,将穿刺活检病理结果与术后病理对照,统计各组穿刺活检的准确率。结果 3组病例穿刺活检病理诊断与术后病理相符者均为98例,诊断准确率均为98%（P〉0.05）。A、B 2组各有1例穿刺活检病理诊断为乳腺癌可疑,1例乳腺癌误诊为导管上皮内瘤。C组1例B淋巴细胞瘤误诊为慢性炎症,1例浸润性导管癌误诊为乳腺腺病。结论乳腺数字化三维立体定位穿刺活检所取组织条为2、3、4条的诊断准确率无明显差异。     

铁基非晶合金带材的磁性能检测方法研究

阐述了配电变压器用铁基非晶合金带材磁性能检测的方法,主要涉及用于配电变压器的铁基非晶合金带材工频磁性能检测方法,包括环形试样法和单片法。通过介绍两种检测技术的原理依据、应用现状、适用性及存在的问题,对比分析两种不同方法测量结果的差异,提出一种针对不同样品、不同测试需求选取相应检测技术的方法。     

条带式刚性面板加筋土挡墙筋带应变响应特性研究

 基于大型振动台模型试验,研究条带式刚性面板挡墙在地震波作用下筋带的应变响应特征,并结合土体相对密实度、面板位移以及频谱特征,探究加筋土挡墙的潜在损伤规律。试验结果表明：随着地震波加载幅值增大,筋带主要受力区域从潜在破坏区移至加筋稳定区;对筋带应变分析显示墙内破坏从中部开始,逐渐向下部发展,中下部更易发生破坏;潜在破裂面研究表明挡墙的破裂面形式类似0.3 H(H为墙高)折线形式,但区域大于规范上的破裂面;在0.1 g～0.3 g地震波作用下相对密实度随加载峰值增加而增大,0.4 g以后相对密实度减小,土体发生损伤,与应变规律一致;不同地震波加载前后输入的白噪声傅里叶谱显示,地震波向上传播其频谱由单峰值逐渐发展为双峰值,且0.4 g以后第二峰值频率有逐渐增大趋势。该研究成果可为更加合理地考虑地震区的加筋土挡墙结构的设计提供指导。     

基于GE PA的卷烟厂制丝线MES的设计

分析了卷烟厂制造执行系统的特点以及发展现状。以PA平台为基础,设计了一套卷烟厂制丝线的制造执行系统,主要由系统管理、生产建模、生产管理、质量管理、设备管理、人员管理等模块组成。该系统的开发大大提高了卷烟厂制丝车间的生产管理水平。     

Fatigue behaviour of tensile steel/CFRP joints

In this paper the fatigue performance of tensile steel/CFRP (Carbon Fibre Reinforced Polymer) double shear lap joints is discussed. Joints were realized with two steel plates and two CFRP strips bonded using epoxy adhesive. Fatigue tests were performed on 16 specimens under constant stress range loading cycles. Two stress ratios (R = 0.1 and R = 0.4) were considered to investigate their influence on the fatigue lifetime. Debonding was observed to occur at stress concentration zones and propagate along the CFRP/adhesive interfaces. The stiffness degradation of the steel joint due to progressive debonding of the adhesive represents an index for the subsequent and progressive global failure. S–N curves are defined and compared to the fatigue resistance of welded detail categories of the Eurocode 3. The tests showed that the stress ratio, R, has a marginal influence on the fatigue lifetime of the steel/CFRP double shear lap joints. Finally, a fatigue limit corresponding to a stress range in the steel plate equal to 75 MPa was conservatively estimated during the tests. The fatigue limit seems to be insensitive to the stress ratio R.