Emission characteristics of nonmethane hydrocarbons from private cars and taxis at different driving speeds in Hong Kong

Vehicular emissions are the major sources of a number of air pollutants including nonmethane hydrocarbons (NMHCs) in urban area. The emission composition and emission factors of NMHCs from vehicles are currently lacking in Hong Kong. In this study, speciation and emission factors of NMHCs emitted from gasoline-fuelled private cars and liquefied petroleum gas (LPG)-fuelled taxis at different driving speeds were constructed using a chassis dynamometer. Large variations in the contributions of individual NMHC species to total emission were observed for different private cars at different driving speeds. The variations of individual NMHC emissions were relatively smaller for taxis due to their relatively homogeneous year of manufacture and mileages. Incomplete combustion products like ethane, ethene and propene were the major component of both types of vehicles, while unburned fuel component was also abundant in the exhausts of private cars and taxis (i.e. i-pentane and toluene for private car, and propane and butanes for taxi). Emission factors of major NMHCs emitted from private cars and taxis were estimated. High emission factors of ethane, n-butane, i/n-pentanes, methylpentanes, trimethylpentanes, ethene, propene, i-butene, benzene, toluene and xylenes were found for private cars, whereas propane and i/n-butanes had the highest values for taxis. By evaluating the effect of vehicular emissions on the ozone formation potential (OFP), it was found that the contributions of olefinic and aromatic hydrocarbons to OFP were higher than that from paraffinic hydrocarbons for private car, whereas the contributions of propane and i/n-butanes were the highest for taxis. The total OFP value was higher at lower speeds (≤50 km h-1) for private cars while a minimum value at driving speed of 100 km h-1 was found for taxis. At the steady driving speeds, the total contribution of NMHCs emitted from LPG-fuelled taxis to the OFP was much lower than that from gasoline-fuelled private cars. However, at idling state, the contribution of NMHCs from LPG-fuelled vehicles to OFP was comparable to that from gasoline-fuelled vehicles. The findings obtained in this study can be used to mitigate the air pollution caused by vehicles in highly dense urban areas. © 2011 Elsevier Ltd

TARGET: Rapid Capture of Process Knowledge

TARGET (Task Analysis/Rule Generation Tool) represents a new breed of tool that blends graphical process flow modeling capabilities with the function of a top-down reporting facility. Since NASA personnel frequently perform tasks that are primarily procedural in nature, TARGET models mission or task procedures and generates hierarchical reports as part of the process capture and analysis effort. Historically, capturing knowledge has proven to be one of the greatest barriers to the development of intelligent systems. Current practice generally requires lengthy interactions between the expert whose knowledge is to be captured and the knowledge engineer whose responsibility is to acquire and represent the expert's knowledge in a useful form. Although much research has been devoted to the development of methodologies and computer software to aid in the capture and representation of some types of knowledge, procedural knowledge has received relatively little attention. In essence, TARGET is one of the first tools of its kind, commercial or institutional, that is designed to support this type of knowledge capture undertaking. This paper will describe the design and development of TARGET for the acquisition and representation of procedural knowledge. The strategies employed by TARGET to support use by knowledge engineers, subject matter experts, programmers and managers will be discussed. This discussion includes the method by which the tool employs its graphical user interface to generate a task hierarchy report. Next, the approach to generate production rules for incorporation in and development of a CLIPS based expert system will be elaborated. TARGET also permits experts to visually describe procedural tasks as a common medium for knowledge refinement by the expert community and knowledge engineer making knowledge consensus possible. The paper briefly touches on the verification and validation issues facing the CLIPS rule generation aspects of TARGET. A description of efforts to support TARGET's interoperability issues on PCs, Macintoshes and UNIX workstations concludes the paper

Near Miscible CO2 Application to Improve Oil Recovery

Carbon dioxide (CO2) injection for enhanced oil recovery is a proven technology. CO2 injection is normally operated at a pressure above the minimum miscibility pressure (MMP), which is determined by crude oil composition and reservoir conditions. This is the lowest pressure at which the injected CO2 becomes dynamically miscible with the crude oil remaining in the reservoir. However, many reservoirs are located at depths or under geologic conditions such that they must operate at pressures below the MMP. When CO2 is injected at below the MMP, displacement efficiency decreases as a result of the loss of miscibility. CO2 injection is usually not considered as an enhanced oil recovery process in these reservoirs. Near miscible displacement generally refers to the process that occurs at pressures slightly below the MMP, but the actual pressure range has never been clearly defined. The objectives of this study were to investigate the feasibility of near-miscible CO2 application and improve our understanding of the mechanisms of near-miscible CO2 flooding by conducting appropriate experimental work and reservoir simulation. The pressure range of interest was from 0.8 MMP to MMP in our study. The Arbuckle formation of Kansas was used as an example to demonstrate our approach to evaluate CO2 flooding at near-miscible conditions. The suite of laboratory experiments used to evaluate the feasibility of operating at pressures below MMP for Arbuckle reservoirs included phase behavior studies, core flow tests and phase behavior model construction using CMG software package. Phase behavior studies were carried out to characterize the near miscible conditions. Slim tube displacements and swelling/extraction tests were performed to identify the near miscible range and the mass transfer mechanisms which were responsible for the oil recovery within this range. A phase behavior model was constructed and well-tuned to simulate oil properties, CO2/crude oil interactions and slim tube results. Core flow tests were conducted to evaluate the oil recovery efficiency in the near miscible range. Initial laboratory works indicated that miscibility was not achievable, however at least 65% to 80% of the waterflood residual oil for dolomite cores and lesser from 45% to 60 % for sandstone core in the near-miscible region was observed. The principal oil recovery mechanism in the near-miscible range appeared to be extraction/vaporization of hydrocarbon components from crude oil into the CO2 rich vapor phase, coupled with enhanced mobility control due to the reduction of oil viscosity. This suggested that application of carbon dioxide in the field would require injection and recycling of large volumes of carbon dioxide. Further study is needed to determine if such a process is economically feasible. However the prospect of recovering up to 1 billion barrels of oil from Arbuckle reservoirs offers significant economic potential

Analysis of Heterogeneous Cardiac Pacemaker Tissue Models and Traveling Wave Dynamics

The sinoatrial-node (SAN) is a complex heterogeneous tissue that generates a stable rhythm in healthy hearts, yet a general mechanistic explanation for when and how this tissue remains stable is lacking. Although computational and theoretical analyses could elucidate these phenomena, such methods have rarely been used in realistic (large-dimensional) gap-junction coupled heterogeneous pacemaker tissue models. In this study, we adapt a recent model of pacemaker cells (Severi et al. 2012), incorporating biophysical representations of ion channel and intracellular calcium dynamics, to capture physiological features of a heterogeneous population of pacemaker cells, in particular "center" and "peripheral" cells with distinct intrinsic frequencies and action potential morphology. Large-scale simulations of the SAN tissue, represented by a heterogeneous tissue structure of pacemaker cells, exhibit a rich repertoire of behaviors, including complete synchrony, traveling waves of activity originating from periphery to center, and transient traveling waves originating from the center. We use phase reduction methods that do not require fully simulating the large-scale model to capture these observations. Moreover, the phase reduced models accurately predict key properties of the tissue electrical dynamics, including wave frequencies when synchronization occurs, and wave propagation direction in a variety of tissue models. With the reduced phase models, we analyze the relationship between cell distributions and coupling strengths and the resulting transient dynamics. Further, the reduced phase model predicts parameter regimes of irregular electrical dynamics. Thus, we demonstrate that phase reduced oscillator models applied to realistic pacemaker tissue is a useful tool for investigating the spatial-temporal dynamics of cardiac pacemaker activity.Comment: 34 pages, 11 figure

Exposure to hazardous volatile organic compounds, PM 10 and CO while walking along streets in urban Guangzhou, China

Toxic air pollutants in street canyons are important issues concerning public health especially in some large Asian cities like Guangzhou. In 1998 <18% of Guangzhou citizens used public transportation modes, with a majority commuting on foot (42%) or by bicycle (22%). Of the pedestrians, 57% were either senior citizens or students. In the present study, we measured toxic air pollutants while walking along urban streets in Guangzhou to evaluate pedestrian exposure. Volatile organic compounds (VOCs) were collected with sorbent tubes, and PM 10 and CO were measured simultaneously with portable analyzers. Our results showed that pedestrian exposure to PM 10 (with an average of 303 μg m -3 for all samples) and some toxic VOCs (for example, benzene) was relatively high. Monocyclic aromatic hydrocarbons were found to be the most abundant VOCs, and 71% of the samples had benzene levels higher than 30 μg m -3. Benzene, PM 10 and CO in walk-only streets were significantly lower (p<0.05) than in traffic streets, and the differences in exposure levels between new urban streets and old urban streets were highly significant (p<0.01). Pedestrian exposure to toxic VOCs and PM 10 was higher than those reported in other public transportation modes (bus and subway). The good correlations between BTEX, PM 10 and CO in the streets indicated that automotive emission might be their major source. Our study also showed that the risk to pedestrians due to air pollution was misinterpreted by the reported air quality index based on measurement of SO 2, NO x and PM 10 in the government monitoring stations. An urban roadside monitoring station might be needed by air quality monitoring networks in large Asian cities like Guangzhou, in order to survey exposure to air toxics in urban roadside microenvironments. © 2004 Elsevier Ltd. All rights reserved

A numerical study of the nonlinear interaction of Hurricane Camille with the Gulf of Mexico Loop Current

A three-dimensional, primitive equation, ocean general circulation model is used to study the response of the Gulf of Mexico to Hurricane Camille (1969). The free-surface dynamics and the mixed-layer features are included in the model. The numerical model incorporates the realistic coastline and bottom topography. The sigma coordinate model bas eighteen levels in the vertical and 0.2° x 0.2° horizontal resolution for the entire gulf. The study focuses on nonlinear interaction between hurricane induced currents and the Loop Current. The numerical simulations show that there is a strong nonlinear interaction between the hurricane and the Loop Current in the southern and central parts of the eastern gulf. The surface currents due to nonlinear interaction obtain a maximum of over 1 m s·1 in the southern gulf. The numerical results also show that the hurricane interaction with the Loop Current strongly affects current, mixed-layer depth, and elevation fields. There is a strong current response to Hurricane Camille in the surface layer on the shelf with a peak velocity approximately 2.2 m s-1• There is a definite right band bias in the mixed-layer depth field with a maximum of about 90 m.Navy Ocean Modeling and Prediction Program (NOMP) of the Office of Naval Research (ONR)Department of Oceanography, Naval Postgraduate SchoolNOAA Great Lakes Environmental Research LabsOceanweather, IncResearch Triangle InstituteNavy Ocean Modeling and Prediction Program (NOMP) of the Office of Naval Research (ONR)Department of Oceanography, Naval Postgraduate SchoolNOAA Great Lakes Environmental Research LabsOceanweather, IncResearch Triangle Institut

Characteristics of nonmethane hydrocarbons (NMHCs) in industrial, industrial-urban, and industrial-suburban atmospheres of the Pearl River Delta (PRD) region of south China

In a study conducted in late summer 2000, a wide range of volatile organic compounds (VOCs) were measured throughout five target cities in the Pearl River Delta (PRD) region of south China. Twenty-eight nonmethane hydrocarbons (NMHCs; 13 saturated, 9 unsaturated, and 6 aromatic) are discussed. The effect of rapid industrialization was studied for three categories of landuse in the PRD: Industrial, industrial-urban, and industrial-suburban. The highest VOC mixing ratios were observed in industrial areas. Despite its relatively short atmospheric lifetime (2-3 days), toluene, which is largely emitted from industrial solvent use and vehicular emissions, was the most abundant NMHC quantified. Ethane, ethene, ethyne, propane, n-butane, i-pentane, benzene, and m-xylene were the next most abundant VOCs. Direct emissions from industrial activities were found to greatly impact the air quality in nearby neighborhoods. These emissions lead to large concentration variations for many VOCs in the five PRD study cities. Good correlations between isoprene and several short-lived combustion products were found in industrial areas, suggesting that in addition to biogenic sources, anthropogenic emissions may contribute to urban isoprene levels. This study provides a snapshot of industrial, industrial-urban, and industrial-suburban NMHCs in the five most industrially developed cities of the PRD. Increased impact of industrial activities on PRD air quality due to the rapid spread of industry from urban to suburban and rural areas, and the decrease of farmland, is expected to continue until effective emission standards are implemented. Copyright 2006 by the American Geophysical Union

Pengaruh Suplementasi Saccharomyces Cerevisiae sebagai Probiotik dalam Ransum Berbasis Pakan Lokal terhadap Performans dan Kecernaan Nutrisi pada Babi Lokal Fase Starter

The long term purposes of the study are to change the mind and the custom of pigs farmers from using restaurant or household wastes to using local feeds enriched with yeast (Saccharomyces cerevisiae). The short term or special purpose of the study are to find out the cheaper alternative feeds for pigs and information of using yeast to improve feeds quality and pigs productivity. The study with those purposes was carried out off farm by supplementing yeast into low quality pig feeds (crude protein/CP ≤ 16%) of local weaned pigs composed of: corn meal, rice brand, soybean/tofu extract and unused fish meal. 12 local weaned pigs were fed 4 treatment diets based on block design of 4 treatments with 3 blocks design procedure. The 4 treatment feeds were formulated as : R0 (commercial diet/551); R1 (basal feed + 2% yeast of daily requirement); R2 (basal feed + 4% yeast of daily requirement); and R3 (basal feed + 6% yeast of daily requirement). Feed intake, daily weight gain, feeds conversion efficiency, protein, and crude fibre digestibility were studied in the study. Statistical analysis showed that the effect of the treatments is not significant (P>0.05) on all variables studied. Supplementation yeast of 6% is the best treatment performing the highest result of most variable studied. The conclusion drawn is that supplementing yeast up to 6% could improve performance of weaned pigs fed low quality feed and perform the similar result with feeding commercial feed (551). It is suggested to use yeast up to 6% in the diet and further research including widen range and high level of yeast supplementation could be done