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Item Continuous-flow sorting of microalgae cells based on lipid content by high frequency dielectrophoresis(2016) Gharehghieh, Hanieh H.; Redelman, Doug; Hiibel, Sage R.; Geiger, Emil J.This paper presents a continuous-flow cell screening device to isolate and separate microalgae cells (Chlamydomonas reinhardtii) based on lipid content using high frequency (50 MHz) dielectrophoresis. This device enables screening of microalgae due to the balance between lateral DEP forces relative to hydrodynamic forces. Positive DEP force along with amplitude-modulated electric field exerted on the cells flowing over the planar interdigitated electrodes, manipulated low-lipid cell trajectories in a zigzag pattern. Theoretical modelling confirmed cell trajectories during sorting. Separation quantification and sensitivity analysis were conducted with time-course experiments and collected samples were analysed by flow cytometry. Experimental testing with nitrogen starved dw15-1 (high-lipid, HL) and pgd1 mutant (low-lipid, LL) strains were carried out at different time periods, and clear separation of the two populations was achieved. Experimental results demonstrated that three populations were produced during nitrogen starvation: HL, LL and low-chlorophyll (LC) populations. Presence of the LC population can affect the binary separation performance. The continuous-flow micro-separator can separate 74% of the HL and 75% of the LL out of the starting sample using a 50 MHz, 30 voltages peak-to-peak AC electric field at Day 6 of the nitrogen starvation. The separation occurred between LL (low-lipid: 86.1% at Outlet # 1) and LC (88.8% at Outlet # 2) at Day 9 of the nitrogen starvation. This device can be used for onsite monitoringItem Role of Trapped Air on the Tsunami-Induced Transient Loads and Response of Coastal Bridges(2019) Istrati, Denis; Buckle, Ian G.In response to the extensive damage of coastal bridges sustained in recent tsunamis, this paper describes an investigation into tsunami-induced effects on two common bridge types, an open-girder deck with cross-frames and one with solid diaphragms. To this end, large-scale (1:5) physical models with realistic structural members and elastomeric bearings were constructed and tested under a range of unbroken solitary waves and more realistic tsunami-like transient bores. The flexible bearings allowed the superstructure to rotate and translate vertically, thus simulating the wave-structure interaction during the tsunami inundation. Detailed analysis of the experimental data revealed that for both bridge types the resistance mechanism and transient structural response is characterized by a short-duration phase that introduces the maximum overturning moment, upward movement, and rotation of the deck, and a longer-duration phase that introduces significant uplift forces but small moment and rotation due to the fact that the wave is approaching the point of rotation. In the former phase the uplift is resisted mainly by the elastomeric bearings and columns offshore of the center of gravity of the superstructure (C.G.), maximizing their uplift demand. In the latter phase the total uplift is distributed more equally to all the bearings, which tends to maximize the uplift demand in the structural members close to the C.G. The air-entrapment in the chambers of the bridge with diaphragms modifies the wave-structure interaction, introducing (a) a different pattern and magnitude of wave pressures on the superstructure due to the cushioning effect (b) a 39% average and 148% maximum increase in the total uplift forces and (c) a 32% average increase of the overturning moment, which has not been discussed in previous studies. Deciphering the exact effect of the trapped air on the total uplift forces is challenging because, although the air consistently increases the quasi-static component of the force, it has an inconsistent and complex effect on the slamming component, which can either increase or decrease. Interestingly, the air also has a complex effect on the uplift demand in the offshore bearings and columns, which can decrease or increase even more than the total deck uplift, and an inconsistent effect on the uplift force of different structural components introduced by the same wave. These are major findings because they demonstrate that the current approach of investigating the effect of trapped air only on the total uplift is insufficient. Last but not least, the study reveals the existence of significant differences in the effects introduced by solitary waves and transient bores, especially when air is trapped beneath the deck it also provides practical guidance to engineers, who are advised to design the elastomeric bearings offshore of the C.G. for at least 60% and 50% of the total induced uplift force, respectively, for a bridge with cross-frames and one with diaphragms, instead of distributing the total uplift equally to all bearings.Item A signal timing assignment proposal for urban multi lane staged controlled signalised roundabouts(2019) Murat, Yetis Sazi; Cakici, Ziya; Tian, ZongThe relationship between the left-turning traffic volume and the storage area at signalised roundabouts is investigated, and a calculation procedure for signal timing is proposed in this paper. The parameters associated with the developing stages of a new expression/model are also defined. Four different signal timing scenarios are considered. The results show that the proposed formula can be used for the design of signalised roundabouts.Item Iron-bound organic carbon in forest soils: quantification and characterization(2016) Zhao, Qian; Poulson, Simon R.; Obrist, Daniel; Sumaila, Samira; Dynes, James J.; McBeth, Joyce M.; Yang, YuIron oxide minerals play an important role in stabilizing organic carbon (OC) and regulating the biogeochemical cycles of OC on the earth surface. To predict the fate of OC, it is essential to understand the amount, spatial variability, and characteristics of Fe-bound OC in natural soils. In this study, we investigated the concentrations and characteristics of Fe-bound OC in soils collected from 14 forests in the United States and determined the impact of ecogeographical variables and soil physicochemical properties on the association of OC and Fe minerals. On average, Fe-bound OC contributed 37.8% of total OC (TOC) in forest soils. Atomic ratios of OC: Fe ranged from 0.56 to 17.7, with values of 1-10 for most samples, and the ratios indicate the importance of both sorptive and incorporative interactions. The fraction of Fe-bound OC in TOC (f(Fe-OC)) was not related to the concentration of reactive Fe, which suggests that the importance of association with Fe in OC accumulation was not governed by the concentration of reactive Fe. Concentrations of Fe-bound OC and f(Fe-OC) increased with latitude and reached peak values at a site with a mean annual temperature of 6.6 degrees C. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and near-edge X-ray absorption fine structure (NEXAFS) analyses revealed that Fe-bound OC was less aliphatic than non-Fe-bound OC. Fe-bound OC also was more enriched in C-13 compared to the non-Fe-bound OC, but C/N ratios did not differ substantially. In summary, C-13-enriched OC with less aliphatic carbon and more carboxylic carbon was associated with Fe minerals in the soils, with values of f(Fe-OC) being controlled by both sorptive and incorporative associations between Fe and OC. Overall, this study demonstrates that Fe oxides play an important role in regulating the biogeochemical cycles of C in forest soils and uncovers the governing factors for the spatial variability and characteristics of Fe-bound OC.Item Data Registration with Ground Points for Roadside LiDAR Sensors(2019) Yue, Rui; Xu, Hao; Wu, Jianqing; Sun, Renjuan; Yuan, ChangweiThe Light Detection and Ranging (LiDAR) sensors are being considered as new traffic infrastructure sensors to detect road users' trajectories for connected/autonomous vehicles and other traffic engineering applications. A LiDAR-enhanced traffic infrastructure system requires multiple LiDAR sensors around intersections, along with road segments, which can provide a seamless detection range at intersections or along arterials. Each LiDAR sensor generates cloud points of surrounding objects in a local coordinate system with the sensor at the origin, so it is necessary to integrate multiple roadside LiDAR sensors' data into the same coordinate system. None of existing methods can integrate the data from roadside LiDAR sensors, because the extensive detection range of roadside sensors generates low-density cloud points and the alignment of roadside sensors is different from mapping scans or autonomous sensing systems. This paper presents a method to register datasets from multiple roadside LiDAR sensors. This approach innovatively integrates LiDAR datasets with 3D cloud points of road surface and 2D reference point features, so the method is abbreviated as RGP (Registration with Ground and Points). The RGP method applies optimization algorithms to identify the optimized linear coordinate transformation. This research considered the genetic algorithm (global optimization) and the hill climbing algorithm (local optimization). The performance of the RGP method and the different optimization algorithms was evaluated with field LiDAR sensors data. When the developed process can integrate data from roadside sensors, it can also register LiDAR sensors' data on an autonomous vehicle or a robot.