Experiments on Surface Reconstruction for Partially Submerged Marine Structures

Over the past 10 years, significant scientific effort has been dedicated to the problem of three‐dimensional (3‐D) surface reconstruction for structural systems. However, the critical area of marine structures remains insufficiently studied. The research presented here focuses on the problem of 3‐D surface reconstruction in the marine environment. This paper summarizes our hardware, software, and experimental contributions on surface reconstruction over the past few years (2008–2011). We propose the use of off‐the‐shelf sensors and a robotic platform to scan marine structures both above and below the waterline, and we develop a method and software system that uses the Ball Pivoting Algorithm (BPA) and the Poisson reconstruction algorithm to reconstruct 3‐D surface models of marine structures from the scanned data. We have tested our hardware and software systems extensively in Singapore waters, including operating in rough waters, where water currents are around 1–2 m/s. We present results on construction of various 3‐D models of marine structures, including slowly moving structures such as floating platforms, moving boats, and stationary jetties. Furthermore, the proposed surface reconstruction algorithm makes no use of any navigation sensor such as GPS, a Doppler velocity log, or an inertial navigation system.     

Ethnically bounded homeownership: qualitative insights on Los Angeles immigrant homeowners’ experiences during the U.S. Great Recession

Immigrant homeowners’ function within ethnic boundaries in the housing market may have helped or hindered them during the recent U.S. Great Recession. This research explores this theme through interviews with immigrant and non-immigrant homeowners from four ethnic communities in Los Angeles County and the non-profit organizations that tried to assist them. Immigrant homeowners turned to co-ethnics for advice and support and formed multigenerational households as a strategy to achieve and sustain homeownership. Language and cultural barriers primed them for risky loans and thwarted their pursuit of refinance and modification when they struggled to make mortgage payments. These findings conform to existing evidence of ethnic segmentation in the housing market and imply that analyses of home buying and homeownership in areas with significant immigrant populations should factor in the role of ethnicity.     

Thermoelectric and mechanical properties of melt spun and spark plasma sintered n-type Yb- and Ba-filled skutterudites

Here we present thermoelectric and mechanical properties of n-type filled-skutterudites produced by a combination of melt spinning of pre-melted charges with subsequent consolidation by spark plasma sintering, a process we refer to as MS-SPS. This combination of processing steps leads to phase-pure n-type filled-skutterudites and obviates more energy and time intensive annealing steps. We show that both the thermoelectric properties and the tensile fracture strength compare favorably to materials made by traditional methods. The process is scalable to at least 80 g billets, such that the transport properties measured on test bars harvested from these larger billets compare favorably to those measured on lab-scale billets (5 g total billet mass). ZT values approaching 1.1 at 750 K were observed in materials made by MS-SPS. In addition, the tensile fracture strength of test bars cut from an 80 g billet is ∼128 MPa at room temperature and decreases with increasing temperature. Fractography of the test bars reveals that the majority failed due to surface and edge flaws with few failures due to volume type flaws. This indicates that the powder metallurgical methods employed to produce these samples is mature.     

A low-cost projector-based hand-held flexible display system

In this paper, we propose a low-cost hand-held flexible display system which uses a projector to project display content onto an ordinary white paper that can be twisted freely. The ultimate goal is to develop an interactive viewing tool for displaying content on flexible surface that can be deformed by the user, i.e., when the user twists the paper, the display content on the paper deforms simultaneously. This system has a lot of potential in the entertainment and education industries. A pair of cameras is employed to track the pattern printed on the back of paper. The cameras and the projector are calibrated off-line via a simple and convenient method. A real-time algorithm is proposed to recover the 3D surface of the paper. The display content is then pre-warped according to the recovered surface and projected onto the front of the paper. Two demonstrative applications are elaborated to illustrate the potential of the proposed system. Our system is easy to set up and runs in real-time. Experimental results show that the flexible display is created with satisfactory accuracy and robustness.     

Assessing the Effects of Acute Amyloid β Oligomer Exposure in the Rat

Alzheimer’s disease (AD) is the most common form of dementia, yet there are no therapeutic treatments that can either cure or delay its onset. Currently, the pathogenesis of AD is still uncertain, especially with respect to how the disease develops from a normal healthy brain. Amyloid β oligomers (AβO) are highly neurotoxic proteins and are considered potential initiators to the pathogenesis of AD. Rat brains were exposed to AβO via bilateral intracerebroventricular injections. Rats were then euthanized at either 1, 3, 7 or 21-days post surgery. Rat behavioural testing was performed using the Morris water maze and open field tests. Post-mortem brain tissue was immunolabelled for Aβ, microglia, and cholinergic neurons. Rats exposed to AβO showed deficits in spatial learning and anxiety-like behaviour. Acute positive staining for Aβ was only observed in the corpus callosum surrounding the lateral ventricles. AβO exposed rat brains also showed a delayed increase in activated microglia within the corpus callosum and a decreased number of cholinergic neurons within the basal forebrain. Acute exposure to AβO resulted in mild learning and memory impairments with co-concomitant white matter pathology within the corpus callosum and cholinergic cell loss within the basal forebrain. Results suggest that acute exposure to AβO in the rat may be a useful tool in assessing the early phases for the pathogenesis of AD.     

Environmental risk management for a cross interchange subway station construction in China

Ground surface settlement induced by urban subway construction using shallow tunnelling method is inevitable and it may cause a series of negative impact to existing nearby structures and utilities. In order to guarantee environmental safety, a risk management methodology which aims at process control for ground settlement and existing nearby structures is proposed. It includes 5-stage technology-based steps: survey of existing conditions, designing control standards for key risk factors, analyzing environmental response under tunnel construction and designing process control standards, monitoring and taking proper process control measures during construction, and risk reassessment after construction. This methodology was put into practice in the Huangzhuang subway station construction which is the largest cross interchange subway station construction using shallow tunnelling method in China. According to site survey, nearby pipelines and existing buildings were determined to be the key risk factors. The risk control standards for nearby pipelines and existing buildings were made according to available standards in China and related literatures. Design of process control standards for ground surface settlement was assisted by numerical simulation, which aimed at controlling the key risk factors. During construction, monitoring was adopted for the nearby pipelines, existing buildings and ground surface. After the four drifts excavation of the double-deck part of Line 4, a series of risk control measures, which included treatment of the unfavorable geological bodies, installation of roof pipes, compensation grouting, full-face grouting and some other control measures, were taken. Due to these risk control measures, ground surface settlements, except at two measuring points of Line 4, were successfully controlled under the given process control standards for both Line 4 and Line 10. All the pipelines and buildings were under their normal service state during tunnel construction. The maximum deflection for the 6 pipelines above the station was controlled to be within 2 mm/m and the maximum settlement of all the monitoring points for the pipelines was less than 30 mm. For the four important existing buildings in close vicinity, the maximum deflection was less than 1 mm/m; the maximum settlement value was 6.8 mm and the maximum uplift value was 3.0 mm. The risk control system was shown to be effective in ensuring environment safety, structure safety and construction safety. These safety control methods, the methodology of designing these control standards and the measures taken in the construction can serve as a practical reference for other similar projects.     

Fluctuation Behaviors of Air Pressure in a High-Rise Building Drainage System

Air pressure fluctuation behaviors in a high-rise building drainage system (HBDS) are presented by probability density functions and statistical analysis of measured data in the drainage stack in a real-life eighteen-floor building, the Li Ka-Shing (LKS), at PolyU of Hong Kong. Three observation points, at the mezzanine (M), 6th, and 12th floors, are arranged to record the air pressure in the primary building stack. The measured data are stored in a personal computer with a sampling period of 1?s. Statistical analysis revealed that there is an evident floor dependence of the air pressure in the real-life HBDS. The flatness factor of the pressure fluctuation increases with floor number, whereas the skewness factor has a reversed variation tendency; it decreases from a positive value in the M floor to negative values at higher floors. Probability density functions show the pressure fluctuation behaviors are far from normal distributions.     

Implicit measures of early-life family conditions: Relationships to psychosocial characteristics and cardiovascular disease risk in adulthood.

Objectives: An implicit measure of early-life family conditions was created to help address potential biases in responses to self-reported questionnaires of early-life family environments. We investigated whether a computerized affect attribution paradigm designed to capture implicit, affective responses (anger, fear, warmth) regarding early-life family environments was (a) stable over time, (b) associated with self-reports of childhood family environments, (c) able to predict adult psychosocial profiles (perceived social support, heightened vigilance), and (d) able to predict adult cardiovascular risk (blood pressure) either alone or in conjunction with a measure of early-life socioeconomic status. Method: Two studies were conducted to examine reliability and validity of the affect attribution paradigm (Study 1, N = 94) and associated adult psychosocial outcomes and cardiovascular risk (Study 2, N = 122). Results: Responses on the affect attribution paradigm showed significant correlations over a 6-month period, and were moderately associated with self-reports of childhood family environments. Greater attributed negative affect about early-life family conditions predicted lower levels of current perceived social support and heightened vigilance in adulthood. Attributed negative affect also interacted with early-life socioeconomic status (SES) to marginally predict resting systolic blood pressure (SBP), such that those individuals high in early-life SES but who had implicit negative affect attributed to early-life family conditions had SBP levels that were as high as individuals low in early-life SES. Conclusion: Implicit measures of early-life family conditions are a useful approach for assessing the psychosocial nature of early-life environments and linking them to adult psychosocial and physiological health profiles. (PsycINFO Database Record (c) 2011 APA, all rights reserved)