Seismic stops vs. snubbers, a reliable alternative

The Seismic Stops methodology has been developed to provide a reliable alternative for providing seismic support to nuclear power plant piping. The concept is based on using rigid passive supports with large clearances. These gaps permit unrestrained thermal expansion while limiting excessive seismic displacements. This type of restraint has performed successfully in fossil fueled power plants.A simplified production analysis tool has been developed which evaluates the nonlinear piping response including the effect of the gapped supports. The methodology utilizes the response spectrum approach and has been incorporated into a piping analysis computer program RLCA-GAP.Full scale shake table tests of piping specimens were performed to provide test correlation with the developed methodology. Analyses using RLCA-GAP were in good agreement with test results. A sample piping system was evaluated using the Seismic Stops methodology to replace the existing snubbers with passive gapped supports. To provide further correlation data, the sample system was also evaluated using nonlinear time history analysis. The correlation comparisons showed RLCA-GAP to be a viable methodology and a reliable alternative for snubber optimization and elimination.     

BIM 与云、大数据、物联网等技术的 集成应用现状与未来

近年来,云计算、大数据、物联网等技术不断涌现,并与建设工程中建筑信息模 型(BIM)技术的应用不断融合,越来越受到研究人员的关注。然而,这些技术尚未形成面向建 设项目的统一集成应用框架。通过广泛的文献调研发现,云、大数据、物联网与 BIM 技术缺一 不可,只有将其充分集成才能共同发挥价值,服务建设项目建设、管理。在此基础上,研究建 立了各项技术的统一集成应用框架。同时,从理论和应用两方面对有关技术与 BIM 技术集成的 研究与应用现状进行了综述,梳理了各项关键技术及软件系统研发现状,对已有工程应用进行 了总结。最后,对研究中存在的瓶颈与挑战进行了分析,指出未来仍需在基础理论方法、多技 术融合等方面开展深入研究。     

A Hallen-type integral equation for symmetric scattering from lossycircular disks

A rigorous technique is presented for calculating the current induced on a thin lossy disk by rotationally symmetric sources, and the resulting scattered field. A Hallen-type integral equation is developed for the current using the magnetic vector potential, and it is solved by the method of moments. It is shown that the diffraction lobes usually associated with radiation above a finite circular ground plane can be reduced dramatically by the addition of loss. Application to a quarter-wave monopole radiating above a finite circular perfectly conducting ground plane shows good agreement with experiment     

Declarative and procedural learning, quantitative measures of the hippocampus, and subcortical white alterations in Alzheimer's disease and ischaemic vascular dementia

This research investigated whether subjects with Alzheimer's disease (AD) and ischaemic vascular dementia (IVD) associated with periventricular and deep white matter alterations can be dissociated on tests of declarative and procedural memory, as well as on MRI indices of white matter alterations and the size of the hippocampal formation. The California Verbal Learning Test (CVLT) and the Pursuit Rotor Learning Tests (PRLT) were used to measure declarative and procedural memory, respectively. Subjects with IVD obtained a higher score on the CVLT recognition discriminability index; however, on the PRLT total time on target, carry-over between trial blocks, and slope calculated for all test trials was low. Subjects with AD exhibited the opposite profile. MRI studies indicated that subjects with IVD had considerably greater white matter alterations, but larger hippocampal formations than subjects with AD. Higher scores on the CVLT recognition discriminability index were correlated with increased size of the body of the hippocampus and parahippocampal gyrus. By contrast, as the severity of white matter alterations increased the slope on the PRLT declined. In sum, subjects with AD and IVD can be dissociated on the basis of differing patterns of impairment on tests of declarative and procedural memory, and MRI indices of white matter alteration and the integrity of the hippocampal formation.     

Chicken anemia virus

Chicken anemia virus is commonly found in commercially produced chickens and has a worldwide distribution. It is difficult to inactivate thermally or with common disinfectants, which limits the utility of normal sanitization practices. The virus is important because of the disease it produces following transovarian transmission and because of its potential for inducing immunosuppression alone or in combination with other infectious agents. Control measures are directed at limiting vertical transmission and preventing coinfections with other lymphocidal agents.     

The emergence of spatial rotation deficits in dementia and normal aging.

The mental rotation required in the Road Map Test of Direction Sense (the "Road Map Test"; J. Money, 1976; J. Money, D. Alexander, & H. T. Walker, 1965) has been thought to be impaired as a function of age, but not dementia. However, spatial rotation in dementia has not been investigated in reference to spatial coordinate systems. Patients with dementia (Alzheimer's and ischemic vascular dementias) and elderly control participants were administered the Road Map Test. The authors analyzed whether the geocentric or egocentric coordinate system determined rotation of Road Map Test turns and predicted impairment in dementia patients. They found equivalent impairment in both types of dementia, greater angulation effect in the geocentric system in patients relative to normal controls, and no egocentric effect. Results also suggest early emergence of spatial rotation deficit in dementia. Spatial rotation is most often associated with working memory, which predicts the correlations found. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal neocortical injuries in rats impair attending but not complex visual processing.

The effects of variations of the distance between the relevant stimuli and the animals' response sites were observed upon the performances of a black–white discrimination habit for normal rats or subjects prepared with either bilateral injuries to the visual or temporal neocortex. In addition, the animals were given a strict test of visual form perception. Subjects with injuries to the visual cortex failed the test of visual form perception but performed like normals in discriminating a spatially discontiguous problem. In contrast, subjects with temporal injuries exhibited enormous performance deficits when trained on a spatially discontiguous problem but performed like normals on the test of form perception. The findings parallel the results of studies using primates and suggest that bitemporal injuries result in impairments of attending and not of complex visual processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A frequency response-based model order selection criterion

The use of weighting sequence models to describe the dynamics of physical systems provides an effective means of translating the uncertainty associated with the model parameter estimates derived from noisy input/output data into corresponding frequency response-uncertainty information. However, an appropriate truncation level must be established to accomplish this task. The truncation problem is addressed from a frequency response perspective, and a criterion based on frequency response considerations is proposed for selecting the proper truncation