Center for Environmental Research and Technology

Riverside, CA, United States

Center for Environmental Research and Technology

Riverside, CA, United States
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Kari D.,University of California at Riverside | Kari D.,Center for Environmental Research and Technology | Wu G.,University of California at Riverside | Wu G.,Center for Environmental Research and Technology | And 2 more authors.
IEEE Intelligent Vehicles Symposium, Proceedings | Year: 2014

This paper introduces a multi-agent systems (MAS) based freight signal priority algorithm with the stated goal of reducing network-wide energy and emissions. The proposed infrastructure and communication protocol is highly flexible in that it can be applied to multiple measures of effectiveness (MOEs) such as energy, emissions, travel delay, or any combination. Furthermore, the adaptive nature of the optimized signal control ensures extension to multiple arterial intersections. The proposed algorithm has been implemented and evaluated on an isolated intersection in the microscopic simulation environment. The results indicate that the application of the proposed Eco-Friendly Freight Signal Priority algorithm improves upon traditional traffic signal priority by providing fuel and travel time savings to both freight and non-freight traffic. © 2014 IEEE.

Qi L.,University of California at Riverside | Qi L.,Center for Environmental Research and Technology | Nakao S.,University of California at Riverside | Nakao S.,Center for Environmental Research and Technology | And 4 more authors.
Atmospheric Chemistry and Physics | Year: 2010

The chemical and physical differences of secondary organic aerosol (SOA) formed at select isothermal temperatures (278 K, 300 K, and 313 K) are explored with respect to density, particle volatility, particle hygroscopicity, and elemental chemical composition. A transition point in SOA density, volatility, hygroscopicity and elemental composition is observed near 290-292K as SOA within an environmental chamber is heated from 278K to 313 K, indicating the presence of a thermally labile compound. No such transition points are observed for SOA produced at 313K or 300K and subsequently cooled to 278 K. The SOA formed at the lowest temperatures (278 K) is more than double the SOA formed at 313 K. SOA formed at 278K is less hydrophilic and oxygenated while more volatile and dense than SOA formed at 300K or 313 K. The properties of SOA formed at 300K and 313K when reduced to 278K did not match the properties of SOA initially formed at 278 K. This study demonstrates that it is insufficient to utilize the enthalpy of vaporization when predicting SOA temperature dependence. © 2010 Author(s).

Giordano M.,University of California at Riverside | Giordano M.,Center for Environmental Research and Technology | Espinoza C.,University of California at Riverside | Espinoza C.,Center for Environmental Research and Technology | And 2 more authors.
Atmospheric Chemistry and Physics | Year: 2015

This study examines the morphological properties of freshly emitted and atmospherically aged aerosols from biomass burning. The impacts of particle morphology assumptions on hygroscopic predictions are examined. Chamber experiments were conducted at the University of California, Riverside, Center for Environmental Research and Technology (CE-CERT) atmospheric processes lab using two biomass fuel sources: manzanita and chamise. Morphological data was obtained through the use of an aerosol particle mass analyzer (APM), scanning mobility particle sizer (SMPS) system and transmission electron microscope (TEM). Data from these instruments was used to calculate both a dynamic shape factor and a fractal-like dimension for the biomass burning emissions. This data was then used with κ-Köhler theory to adjust the calculated hygroscopicity for experimentally determined morphological characteristics of the aerosol. Laboratory measurement of biomass burning aerosol from two chaparral fuels show that particles are nonspherical with dynamic shape factors greater than 1.15 for aerosol sizes relevant to cloud condensation nuclei (CCN) activation. Accounting for particle morphology can shift the hygroscopicity parameter by 0.15 or more. To our knowledge, this work provides the first laboratory chamber measurements of morphological characteristics for biomass burning cloud condensation nuclei and provides experimental particle shape evidence to support the variation in reported hygroscopicities of the complex aerosol. © 2015 Author(s).

Nakao S.,University of California at Riverside | Nakao S.,Center for Environmental Research and Technology | Clark C.,University of California at Riverside | Clark C.,Center for Environmental Research and Technology | And 6 more authors.
Atmospheric Chemistry and Physics | Year: 2011

SOA formation from benzene, toluene, m-xylene, and their corresponding phenolic compounds were investigated using the UCR/CE-CERT Environmental Chamber to evaluate the importance of phenolic compounds as intermediate species in aromatic SOA formation. SOA formation yield measurements coupled to gas-phase yield measurements indicate that approximately 20% of the SOA of benzene, toluene, and m-xylene could be ascribed to the phenolic route under low NOx conditions. The SOA densities tend to be initially as high as approximately 1.8 g cm-3 and eventually reach the range of 1.3-1.4 g cm-3. The final SOA density was found to be independent of elemental ratio (O/C) indicating that applying constant density (e.g., 1.4 g cm-33) to SOA formed from different aromatic compounds tested in this study is a reasonable approximation. Results from a novel on-line PILS-TOFMS (Particle-into-Liquid Sampler coupled with Agilent Time-of-Flight Mass Spectrometer) are reported. Major signals observed by the on-line/off-line Agilent TOFMS indicated that products had the same number of carbon atoms as their parent aromatics, suggesting importance of ring-retaining products or ring-opening products following ring-cleavage. © 2011 Author(s).

News Article | March 25, 2016

« Six automated truck platoons to compete in European Truck Platooning Challenge | Main | Stanford team develops new simple approach for viable Li-metal anodes for advanced batteries » The California Air Resources Board voted 8-3 to relocate its motor vehicle and engine emissions testing and research facility from El Monte to an 18-acre site at the University of California, Riverside, representing a $366-million investment. The board decided that the site would provide the best opportunity for growth in the coming decades and for collaboration with the world-class air quality research already underway at UC Riverside. The ARB recommendation will now be considered by the state’s Joint Legislative Budget Committee. The agency hopes to break ground in 2017 and open in 2020. The decision in Sacramento came after a months-long, joint effort by UCR, the city of Riverside, Riverside County, and the Greater Riverside Chambers of Commerce to demonstrate the advantages of locating the facility in Riverside. More than a dozen proponents of the Riverside site spoke at a hearing last week in El Monte, emphasizing the synergy between the work of the Air Resources Board and research that has been done at UC Riverside’s Center for Environmental Research and Technology (CE-CERT) for decades. The new facility will replace an existing one in El Monte that no longer is adequate for the agency. Agency staff had recommended a site in Pomona, in part because of its proximity to the existing site. But board members ultimately decided that Riverside best fit its long-term needs.

Erupe M.E.,Utah State University | Liberman-Martin A.,Wm Keck Science Center | Silva P.J.,Utah State University | Silva P.J.,U.S. Department of Agriculture | And 4 more authors.
Journal of Chromatography A | Year: 2010

An ion chromatography method with non-suppressed conductivity detection was developed for the simultaneous determination of methylamines (methylamine, dimethylamine, trimethylamine) and trimethylamine-N-oxide in particulate matter air samples. The analytes were well separated by means of cation-exchange chromatography using a 3 mM nitric acid/3.5% acetonitrile (v/v) eluent solution and a Metrosep C 2 250 (250 mm × 4 mm i.d.) separation column. The effects of the different chromatographic parameters on the separation were also investigated. Detection limits of methylamine, dimethylamine, trimethylamine, and trimethylamine-N-oxide were 43, 46, 76 and 72 μg/L, respectively. The relative standard deviations of the retention times were between 0.42% and 1.14% while the recoveries were between 78.8% and 88.3%. The method is suitable for determining if methylamines and trimethylamine-N-oxide are a significant component of organic nitrogen aerosol in areas with high concentration of these species. © 2010 Elsevier B.V.

Hao P.,Center for Environmental Research and Technology | Boriboonsomsin K.,Center for Environmental Research and Technology | Wu G.,Center for Environmental Research and Technology | Barth M.,Center for Environmental Research and Technology
2014 17th IEEE International Conference on Intelligent Transportation Systems, ITSC 2014 | Year: 2014

Mobile sensors have emerged as a promising tool for traffic data collection and performance measurement, but most mobile sensor data today are sparse with low sampling rates, i.e., they are collected from a small subset of vehicles in the traffic stream every 10 to 60 seconds. Therefore, it is challenging to estimate the traffic states in both space and time based on these sparse mobile sensor data. In this paper, a stochastic model is proposed to estimate the second-by-second trajectories using sparse mobile sensor data. The proposed model investigates all possible driving mode sequences between data points. The likelihood of each scenario is quantified with mode-specific a priori distributions. Detailed trajectories are then reconstructed based on the optimal driving mode sequences. The proposed method is calibrated and validated using NGSIM data. It shows a 58.4% improvement on trajectory estimation, and a significant advance on mobility evaluation. © 2014 IEEE.

Li W.,Michigan Technological University | Xin Q.,CAS Dalian Institute of Chemical Physics | Yan Y.,Center for Environmental Research and Technology
International Journal of Hydrogen Energy | Year: 2010

A series of carbon supported Pt-Fe bimetallic nanocatalysts (Pt-Fe/C) with varying Pt:Fe ratio were prepared by a modified ethylene glycol (EG) method, and then heat-treated under H2-Ar (10 vol%-H2) atmosphere at 900 °C. The Pt-Fe/C catalysts were characterized by X-ray diffraction (XRD), transmission electron spectroscopy (TEM), energy dispersive analysis by X-rays (EDX) and induced coupled plasma-atomic emission spectroscopy (ICP-AES). XRD analysis shows that Pt-Fe/C catalysts have small crystalline particles and form better Pt-Fe alloy structure with Fe amount increasing. TEM images evidence that small Pt-Fe nanoparticles homogeneously deposited on carbon support and addition of Fe can effectively prevent Pt particles agglomeration. EDX and ICP-AES show that Fe precursor cannot be fully reduced and deposited on carbon support through the adopted EG reduction approach. The electrochemical surface area of Pt-Fe/C catalyst obtained through hydrogen desorption areas in the CV curve increases with Fe atomic percentage increasing from 0 to ca. 50%, and then decreases with more Fe in the Pt-Fe/C catalyst. RDE tests show that the Pt-Fe/C with a Pt:Fe ratio of 1.2:1 and an optimized lattice parameter of around 3.894 Å has the highest mass activity and specific activity to oxygen reduction reaction (ORR). As cathode catalyst, this Pt-Fe/C (Pt:Fe ratio of 1.2:1) exhibits higher direct methanol fuel cell performance at 90 °C than Pt/C and other Pt-Fe/C catalysts, this could be attributed to its smaller particle size and better Pt-Fe alloy structure. © 2010 Professor T. Nejat Veziroglu.

Qing Q.,Center for Environmental Research and Technology | Yang B.,Center for Environmental Research and Technology | Wyman C.E.,Center for Environmental Research and Technology
Bioresource Technology | Year: 2010

Lignin in pretreated cellulosic biomass can non-productively adsorb cellulase, resulting in loss of a significant portion of this expensive protein. In addition, lignin interferes with the path for cellulase action, slowing down hydrolysis. Thus, the effectiveness of enzymatic hydrolysis of pretreated lignocellulosic biomass can be significantly enhanced if lignin is removed or effectively modified before adding enzymes. In this study, the enzymatic digestibilities of solids resulting from using the surfactants Tween-80, dodecylbenzene sulfonic acid, and polyethylene glycol 4000 during water-only or dilute acid pretreatment of corn stover at 140-220 °C were evaluated. All of these surfactants increased lignin removal during pretreatment and reduced non-productive binding of enzymes on the biomass surface, but Tween-80 increased enzymatic hydrolysis yields and enhanced total sugar recovery more than the other two. Surfactant pretreatment was found to improve lignin solubility, which could improve cellulose digestibility by reducing unproductive binding to enzyme, and also appeared to enhance performance by modifying the biomass surface. © 2010 Elsevier Ltd. All rights reserved.

Kumar R.,Center for Environmental Research and Technology | Kumar R.,900 University Avenue | Kumar R.,Oak Ridge National Laboratory | Hu F.,Oak Ridge National Laboratory | And 10 more authors.
Biotechnology and Bioengineering | Year: 2013

Dilute acid as well as water only (hydrothermal) pretreatments often lead to a significant hemicellulose loss to soluble furans and insoluble degradation products, collectively termed as chars and/or pseudo-lignin. In order to understand the factors contributing to reducing sugar yields from pretreated biomass and the possible influence of hemicellulose derived pseudo-lignin on cellulose conversion at the moderate to low enzyme loadings necessary for favorable economics, dilute acid pretreatment of Avicel cellulose alone and mixed with beechwood xylan or xylose was performed at various severities. Following pretreatment, the solids were enzymatically hydrolyzed and characterized for chemical composition and physical properties by NMR, FT-IR, and SEM imaging. It was found that hemicelluloses (xylan) derived-pseudo-lignin was formed at even moderate severities and that these insoluble degradation products can significantly retard cellulose hydrolysis. Furthermore, although low severity (CSF∼1.94) dilute acid pretreatment of a xylan-Avicel mixture hydrolyzed most of the xylan (98%) and produced negligible amounts of pseudo-lignin, enzymatic conversion of cellulose dropped significantly (>25%) compared to cellulose pretreated alone at the same conditions. The drop in cellulose conversion was higher than realized for cellulase inhibition by xylooligomers reported previously. Plausible mechanisms are discussed to explain the observed reductions in cellulose conversions. © 2012 Wiley Periodicals, Inc.

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