Application of fuzzy logic in internal combustion engines to predict the engine performance

This paper describes an application of fuzzy logic principle for predicting the internal combustion engine performance, emission and combustion characteristics using fish oil biodiesel. Experimental investigations on a single cylinder, constant speed, direct injection diesel engine were carried out under variable load conditions. The performance, emission and combustion characteristics such as brake thermal efficiency, hydrocarbon, exhaust gas temperature, oxides of nitrogen (NO_x), carbon monoxide, smoke, carbon dioxide, ignition delay, combustion delay and maximum rate of pressure rise were considered. Engine performance was measured using an exhaust gas analyser, smoke metre, piezoelectric pressure transducer and crank angle encoder for different fuel blends and engine load conditions. The obtained data were recorded for each experiment and associated data used to develop a multiple inputs and multiple outputs fuzzy logic model. The developed model produced idealised results with the correlation coefficients of 0.988–0.999 and root mean square error, and was found to be useful for predicting the engine performance characteristics with limited number of available data.     

Evaluation of the Alberta air infiltration model using measurements and inter-model comparisons

The Alberta air infiltration model (AIM-2) is a simplified single-zone model for predicting building air infiltration rates with a number of salient features. This paper presents an empirical study of this model using measured data from 16 detached houses in Ottawa, Canada. A single-fan depressurization test was first conducted for each house to determine its leakage characteristics. Then, the tracer gas concentration decay technique was employed to measure air infiltration rates under a wide range of weather conditions. The AIM-2 model was used to predict air infiltration rates for each of the 16 houses for the measured weather conditions. These model predictions were then compared with the air infiltration rates determined with the tracer gas tests. Additionally, the predictions of the AIM-2 model were compared with those of another model, the Lawrence Berkeley Laboratory (LBL) model. The AIM-2 model tended to underestimate air infiltration rates but performed better than the LBL model. On average, the AIM-2 model has an error of 19% while the LBL model has an error of 25%. The AIM-2 model requires an estimation of the house's leakage distribution, which may have contributed to some of this disagreement. An attempt was made to use genetic algorithms to reduce the uncertainty caused by estimating these model inputs.     

Nonlinear Least-Squares Minimization Applied to Tracer Gas Decay for Determining Airflow Rates in a Two-Zone Building

Abstract We developed a method based on tracer gas decay measurements to quantify the airflow rates, including the interzonal airflows, in a two-zone building: different tracer gases were simultaneously pulse-injected into each of the two zones and the evolution of the gas concentrations in each zone was measured; theoretical concentration profiles obtained by solving dynamic material-balance equations for two coupled, well-mixed zones were fit to the experimental data using nonlinear least-squares minimization; and estimates of the airflow rates were iteratively refined until a best fit was achieved between the model and the data. We conducted experiments validating the method in two full-sized rooms of a test house. Airflows were controlled using blowers, and mixing was ensured by the use of fans. Airflow rates inferred by the tracer gas technique agreed with imposed airflow rates within an average absolute error of 8%. Results are also reported for two experiments conducted in the same structure under uncontrolled conditions. Goodness-of-fit tests revealed no statistically significant differences between measured tracer gas concentrations and theoretical concentration profiles constructed using the least-squares parameter estimates.     

Effects of apartment building façade and balcony design on the reduction of exterior noise

The effects of building façade and balcony design on the reduction of exterior noise were investigated by measuring the noise from traffic at an apartment complex located by a road side as well as the sound field characteristics of an area surrounded by four apartment buildings. The efficiency of different balcony forms for reducing exterior noise was determined using a 1:50 scale model and a single spark source. It was found that parapets were more effective in reducing exterior noise than lintels. Based on the measurements of the parapet used for this study and the absorptive materials in the scale model, a maximum noise reduction of 23 dB was obtained. Lastly, a computer simulation was conducted in order to predict the noise reduction level of lintels and parapets. The results of the simulation were compared to the results of the scale model test. Our results indicate that this method of exterior noise reduction can be useful in high-rise buildings where tall barriers cannot be built.     

Measurement of hydrogen peroxide in an advanced oxidation process using an automated biosensor

A hydrogen peroxide biosensor was used to monitor hydrogen peroxide concentrations in a UV/hydrogen peroxide immobilised Fenton advanced oxidation process (AOP). The biosensor is based on gas phase monitoring and thus is more resistant to fouling from the liquid phase constituents of industrial processes. The biosensor is supplied with catalase continually, therefore overcoming any problems with enzyme degradation, which would occur in an immobilised enzyme biosensor. The biosensors response was linear within the experimental range 30-400mg H(2)O(2)l(-1) with a R(2) correlation of 0.99. The hydrogen peroxide monitor was used to monitor residual peroxide in an AOP, operated with a step overload of hydrogen peroxide, with correlation factors of 0.96-0.99 compared to offline hydrogen peroxide determinations by UV spectroscopy. Sparging the sample with nitrogen was found to be effective in reducing the interference from dissolved gases produced with the AOP itself. It is proposed that this biosensor could be used to improve the effectiveness of AOPs via hydrogen peroxide control.     

On an empirical relationship between SO2 concentration and distance from a highway using passive samplers: a case study in Shanghai, China

In this paper, field measurements were performed to determine SO(2) concentration gradients from a highway in Shanghai using passive samplers. It was demonstrated that passive sampling method is a cost-effective and convenient way to monitor specific gaseous pollutants at small scales over long sampling periods in air quality studies. Using function fit analysis for the measured results, a shifted power-law relationship had been found between SO(2) concentration and the distance from a highway. Accordingly, an empirical shifted power-law model was developed for describing and predicting the SO(2) gradients near a highway, in which k is the only parameter and named as diffusion attenuation coefficient. There was a surprisingly significant negative correlation between known SO(2) concentration at reference point (C(0)) and diffusion attenuation coefficient (k). By the correlation equation of C(0) and k, appropriate value of k could be calculated with measured C(0). Therefore, the empirical shifted power-law model developed in this study could be practically and conveniently applied for predicting the SO(2) distributions near a highway with known C(0).     

城市绿地形态对区域环境噪声的影响

在城市尺度,由于城市绿地和建筑对城市环境噪声的影响机制尚不明确,故鲜有研究单独将城市绿地和城市环境噪声联系起来.试图通过对城市绿地形态相关的指标优化来提高城市绿地对区域环境噪声的净衰减量增量.以武汉市武昌区为例,以600 m边长的网格为基本单元对研究区域进行划分,通过声学模拟和校正、空间分析与统计等方法计算各单元内的噪...     

Bulking in activated sludge plants treating paper mill wastewaters

As part of a larger project to examine the causes of bulking in activated sludge plants treating wastewaters from paper mills, two laboratory-scale activated sludge plants were run in parallel. This was to evaluate the impact of variable environmental and operational parameters on the sludge ecology, and in particular, on the filamentous bacteria in the sludge. A survey of paper mills in the UK showed that there was a significant difference between the activated sludge plants at the paper mills using virgin fibre and those using recycled fibre. An examination of samples from activated sludge plants at the paper mills showed that there did not appear to be any significant correlation between filament abundance and the settlement characteristics as measured by stirred specific volume index (SSVI). The surface charge carried by the sludge particles was also measured and it was found that this parameter was better related to the SSVI. Similar results were found for samples from the laboratory plants. Seven different sets of operational conditions were applied to the laboratory-scale plants. These were aimed at simulating the conditions noted for the full-scale plants during the mill survey. The effects of low dissolved oxygen and low organic loading rates were examined. The effect of inorganic sulphur compounds and volatile fatty acids was studied. A change in raw material from virgin fibre to recycled fibre (corrugated paper) caused an immediate and continuous deterioration in settlement. Divalent cations, calcium and magnesium, were found to be successful in controlling settlement in the final clarifier.     

Use of biomarkers in an indoor air study: lack of correlation between aromatic VOCs with respective urinary biomarkers

The benzene and toluene levels inside of eight homes with attached garages were measured during July 1998 in Fairbanks, Alaska. A thermal desorption tube method and charcoal tube method were used to collect and analyze samples (thermal desorption tube method %RDS = 1.9 for n = 6; charcoal tube method %RDS = 6.5 for n = 4). Results for both methods were compared and showed indoor benzene levels ranging between 1.2 and 72 ppbv. The charcoal tube method usually gave lower results than the thermal desorption method. Nevertheless, the difference observed in benzene levels from each method was not significant as determined by application of the Wilcoxon t-test to these data. Using the thermal desorption method, the range of toluene found in homes was 0.1-111 ppbv. A correlation between toluene and benzene levels suggested the same point source. The benzene and toluene content of the indoor air and the number of small engines stored in the attached garage was also correlated. There was no correlation found between the urinary biomarker concentrations and the level of benzene or toluene measured inside the homes in the summer.     

A Review and a Limited Comparison of Methods for Measuring Total Volatile Organic Compounds in Indoor Air

Numerous methods attempt to measure the combined concentrations of volatile organic compounds (VOCs) in indoor air as total VOCs (TVOC). This paper reviews TVOC methods recently presented in the literature and at an international conference on indoor air quality, for the purpose of identifying common practices and of assessing the impacts that choices of sample collection media and analytical methods and instrumentation can have on TVOC results. The paper also presents the results of laboratory and field comparisons of three TVOC methods. These are a flame-ionization-detector (FID) method, a gas chromatography/mass spectrometry (GC/MS) method, and a method employing a photoacoustic infrared (IR) gas monitor. The laboratory experiments were conducted with eight different mixtures of VOCs. The FID method demonstrated an average accuracy of 93 ± 18 percent when the measured values were calculated as concentrations of carbon. The FID and GC/MS methods demonstrated average accuracies of 77±37 and 75±22 percent, respectively, when the measured hydrocarbon-equivalent values were compared to the expected mass concentrations of the mixtures. The higher uncertainty for the FID was largely due to the low mass response of 27 percent for chlorinated compounds. The response of the IR gas monitor varied between 6 and 560 percent for different classes of compounds. Air samples from ten buildings were analyzed by both the FID and GC/MS methods. The results were highly correlated and similar, with the GC/MS values approximately 20 percent higher on average.     

Dental lead levels in residents from industrial and suburban areas of Kuwait

The present study describes lead concentrations in whole incisor teeth (non-carious) of 216 Kuwaiti resident's aged 3-74, collected from industrial and suburban areas of Kuwait. The mean concentration of lead in all age groups (3-74) showed a significant correlation between both the sexes. Statistical analysis showed a significant correlation between lead levels of males compared with industrial and suburban areas. A similar correlation was also noted in the case of females supporting that industrial residents were more exposed to lead levels than those in suburban areas. A further significant correlation was noted between males and females of industrial and suburban areas which showed that males accumulate more lead concentration than females. A significant correlation was not observed when each age group was compared with that of the respective sexes representing industrial and suburban areas. However, a significant correlation was noted when lead levels in each age group was compared with that of the other age groups except in age groups ranging 35-42. The mean lead levels of 216 teeth were in the range 2.21-2.50 micrograms/g which is less than the range indicated by other investigators in the recent past.     

Evaluation of the COMIS Model by Comparing Simulation and Measurement of Airflow and Pollutant Concentration

Abstract This paper describes the measured and calculated results of airflow rates and pollutant concentration profiles in an airtight test house, the aim being to evaluate the calculation model COMIS for multizone air infiltration and pollutant transport. Firstly, the leakage areas of internal doors, exterior walls and windows were measured by the fan pressurization method. Secondly, two measurements were carried out, assuming that the test house consisted of ten zones. The concentrations and injection rate of SF₆ were measured in order to determine the airflow rates by a system identification method. The boundary conditions, such as indoor and outdoor temperatures, wind speed and direction, and wind pressures were also recorded in situ and saved simultaneously on diskettes, using a computerized data acquisition system. Thirdly, the measured boundary data and leakage characteristics were used as input in the simulation of airflow using COMIS; initial concentrations, injection rate, along with the previous data were used for simulating pollutant transport, assuming tracer gas SF6 as a pollutant. Lastly, the comparisons between measurement and simulation results of airflow rates and pollutant concentrations were carried out by linear regression analysis. The correlation coefficient between the measured and calculated air change rates was 0.72, and that for pollutant concentration was 0.94.     

Obtaining progressive chloride profiles in cementitious materials

The ingress of chloride into concrete is controlled by its absorption and diffusion characteristics. The authors have carried out an investigation to monitor the rate of ingress of chlorides during a 48-week cyclic wetting and drying regime using a variety of cement blends, viz. pulverised fuel ash, ground granulated blast furnace slag, metakaolin and microsilica. Chloride profiles were obtained by analysing concrete dust samples extracted from different depths from the surface that was exposed to the chloride exposure regime. The resistivity of the concrete was determined by measuring conductance between pairs of electrodes, in order to assess if this could be used to determine the presence of chlorides. The water absorption (sorptivity) of the concrete was also measured in order to determine if any correlation existed with the chloride ingress. The chloride profiles depended on both the duration of exposure and the type of cementitious material. A linear relationship was established between the depths to a constant chloride concentration of 0.2% by weight of cementitious material and the square root of time, yielding a rate of chloride ingress coefficient. This coefficient was found to depend on the type of cementitious material. The lowest value was obtained for slag concrete and the highest value was found for the OPC concrete. This corresponded well with the results from the resistivity profiles which indicated slag cement was best at resisting chloride penetration and the OPC concrete the worst. The sorptivity decreased significantly after the testing regime, due to pore refinement caused by continued hydration and the binding of chloride ions, leading to a reduction in continuous porosity. No correlation was found between the sorptivity and the rate of chloride ingress, which indicates that the dominant mechanism responsible for the transport of the chloride ions was not absorption.     

Performance of installed cooking exhaust devices

The performance metrics of airflow, sound, and combustion product capture efficiency (CE) were measured for a convenience sample of 15 cooking exhaust devices, as installed in residences. Results were analyzed to quantify the impact of various device- and installation-dependent parameters on CE. Measured maximum airflows were 70% or lower than values noted on product literature for 10 of the devices. Above-the-cooktop devices with flat-bottom surfaces (no capture hood)--including exhaust fan/microwave combination appliances--were found to have much lower CE at similar flow rates, compared to devices with capture hoods. For almost all exhaust devices and especially for rear-mounted downdraft exhaust and microwaves, CE was substantially higher for back compared with front burner use. Flow rate, and the extent to which the exhaust device extends over the burners that are in use, also had a large effect on CE. A flow rate of 95 liters per second (200 cubic feet per minute) was necessary, but not sufficient, to attain capture efficiency in excess of 75% for the front burners. A-weighted sound levels in kitchens exceeded 56 dB* when operating at the highest fan setting for all 14 devices evaluated for sound performance. PRACTICAL IMPLICATIONS: Natural gas cooking burners and many cooking activities emit pollutants that can reach hazardous levels in homes. Venting range hoods and other cooking exhaust fans are thought to provide adequate protection when used. This study demonstrates that airflows of installed devices are often below advertised values and that less than half of the pollutants emitted by gas cooking burners are removed during many operational conditions. For many devices, achieving capture efficiencies that approach or exceed 75% requires operation at settings that produce prohibitive noise levels. While users can improve performance by preferentially using back burners, results suggest the need for improvements in hood designs to achieve high pollutant capture efficiencies at acceptable noise levels.     

Characterization of emissions from burning incense

The primary objective of this study was to improve the characterization of particulate matter emissions from burning incense. Emissions of particulate matter were measured for 23 different types of incense using a cyclone/filter method. Emission rates for PM2.5 (particulate matter less than 2.5 microm in aerodynamic diameter) ranged from 7 to 202 mg/h, and PM2.5 emission factors ranged from 5 to 56 mg/g of incense burned. Emission rates were also determined using an electrical low pressure impactor (ELPI) and a small electrostatic precipitator (ESP), and emission rates were compared to those determined using the cyclone/filter method. Emission rates determined by the ELPI method were consistently lower than those determined by the cyclone/filter method, and a linear regression correlation was found between emission rates determined by the two methods. Emission rates determined by the ESP method were consistently higher than those determined by the cyclone/filter method, indicating that the ESP may be a more effective method for measuring semivolatile particle emissions. A linear regression correlation was also found between emission rates determined by the ESP and cyclone/filter methods. Particle size distributions were measured with the ELPI, and distributions were found to be similar for most types of incense that were tested. Size distributions by mass typically ranged from approximately 0.06 to 2.5 microm in aerodynamic diameter, with peak values between 0.26 and 0.65 microm. Results indicated that burning incense emits fine particulate matter in large quantities compared to other indoor sources. An indoor air quality model showed that indoor concentrations of PM25 can far exceed the outdoor concentrations specified by the US EPA's National Ambient Air Quality Standards (NAAQS), so incense smoke can pose a health risk to people due to inhalation exposure of particulate matter. Emissions of carbon monoxide (CO), nitric oxide (NO), and sulfur dioxide (SO2) were also measured for seven types of incense. Emission rates of the gaseous pollutants were sufficient to cause indoor concentrations, estimated using the indoor air quality model, to exceed the outdoor concentrations specified by the NAAQS under certain conditions. However, the incense samples that were tested would fill a room with thick smoke under these conditions.     

Wind tunnel tests on the dispersion of vehicular pollutants in an urban area

Results are presented from an extensive series of wind tunnel tests to investigate the dispersion of a tracer gas emitted from a ground level source on a 1 : 125th scale model of an urban area typical of those found in the UK. Concentrations of a tracer gas, propane in air, were measured at a number of pedestrian level locations around the model using fast-response flame ionisation detectors. These were supplemented by pedestrian level wind speed measurements using hot-film anemometry. Measurements were made for changes in the wind azimuth angle and for changes to the building geometry. General conclusions were drawn about the relationships between building geometry and the pedestrian level atmospheric environment and a number of simple empirical relationships derived between the changes in the measured wind characteristics and the characteristics of tracer concentration. Both mean and fluctuating wind speeds and concentrations were measured in the experiments and subsequently quantified using a novel empirical method that may potentially be of use to both urban planners and wind tunnel engineers.     

Measuring the exposure of infants and children to indoor air pollution from biomass fuels in The Gambia

Indoor air pollution (IAP) from biomass fuels contains high concentrations of health damaging pollutants and is associated with an increased risk of childhood pneumonia. We aimed to design an exposure measurement component for a matched case-control study of IAP as a risk factor for pneumonia and severe pneumonia in infants and children in The Gambia. We conducted co-located simultaneous area measurement of carbon monoxide (CO) and particles with aerodynamic diameter <2.5 microm (PM(2.5)) in 13 households for 48 h each. CO was measured using a passive integrated monitor and PM(2.5) using a continuous monitor. In three of the 13 households, we also measured continuous PM(2.5) concentration for 2 weeks in the cooking, sleeping, and playing areas. We used gravimetric PM(2.5) samples as the reference to correct the continuous PM(2.5) for instrument measurement error. Forty-eight hour CO and PM(2.5) concentrations in the cooking area had a correlation coefficient of 0.80. Average 48-h CO and PM(2.5) concentrations in the cooking area were 3.8 +/- 3.9 ppm and 361 +/- 312 microg/m3, respectively. The average 48-h CO exposure was 1.5 +/- 1.6 ppm for children and 2.4 +/- 1.9 ppm for mothers. PM(2.5) exposure was an estimated 219 microg/m3 for children and 275 microg/m3 for their mothers. The continuous PM(2.5) concentration had peaks in all households representing the morning, midday, and evening cooking periods, with the largest peak corresponding to midday. The results are used to provide specific recommendations for measuring the exposure of infants and children in an epidemiological study. PRACTICAL IMPLICATIONS: Measuring personal particulate matter (PM) exposure of young children in epidemiological studies is hindered by the absence of small personal monitors. Simultaneous measurement of PM and carbon monoxide suggests that a combination of methods may be needed for measuring children's PM exposure in areas where household biomass combustion is the primary source of indoor air pollution. Children's PM exposure in biomass burning homes in The Gambia is substantially higher than concentrations in the world's most polluted cities.     

Transport of airborne particles within a room

The objective of this study is to test a technique used to analyze contaminant transport in the wake of a bluff body under controlled experimental conditions for application to aerosol transport in a complex furnished room. Specifically, the hypothesis tested by our work is that the dispersion of contaminants in a room is related to the turbulence kinetic energy and length scale. This turbulence is, in turn, determined by the size and shape of furnishings within the room and by the ventilation characteristics. This approach was tested for indoor dispersion through computational fluid dynamics simulations and laboratory experiments. In each, 3 mum aerosols were released in a furnished room with varied contaminant release locations (at the inlet vent or under a desk). The realizable k approximately epsilon model was employed in the simulations, followed by a Lagrangian particle trajectory simulation used as input for an in-house FORTRAN code to compute aerosol concentration. For the experiments, concentrations were measured simultaneously at seven locations by laser photometry, and air velocity was measured using laser Doppler velocimetry. The results suggest that turbulent diffusion is a significant factor in contaminant residence time in a furnished room. This procedure was then expanded to develop a simplified correlation between contaminant residence time and the number of enclosing surfaces around a point containing the contaminant. Practical Implications The work presented here provides a methodology for relating local aerosol residence time to properties of room ventilation and furniture arrangement. This technique may be used to assess probable locations of high concentration by knowing only the particle release location, furniture configuration, inlet and outlet locations, and air speeds, which are all observable features. Applications of this method include development of 'rules of thumb' for first responders entering a room where an agent has been released and selection of sampler locations to monitor conditions in sensitive areas.     

A wind-tunnel study on diffusion from urban major roads

We evaluate the performance of reduced-scale wind-tunnel experiments that simulate vehicle-induced pollutant diffusion in urban roadside area. From Japanese urban areas, we selected four sites that cover a wide range of road structures, building density, and roadside features. At each site, four field stations were installed to monitor concentration of air pollutants including nitrogen oxides (NOx). In the wind-tunnel experiments, ethane was emitted from along the major roads, and its concentration was compared with the background-subtracted field values. For annual average of NOx in the year 2006, we found that an appropriately normalized concentration agreed fairly well between wind-tunnel and field measurements. The wind-tunnel concentration distribution measured at a high spatial resolution revealed that roadside features such as tall buildings, noise barriers, and trees have considerable effect on the concentration on the downwind or upwind side of the roads. The high-resolution results are expected to serve as a useful database for evaluating numerical air pollution models.     

Is human hair a dosimeter for endogenous zinc and other trace elements?

This work incorporates an assessment of the potential of human hair to monitor ingestion of trace elements from the environment. Included is a report of a study of Zn levels in the facial hair of one of the authors, who was dosed with ZnSO₄. Daily doses increasing from 100 to 300 mg Zn were taken for 57 days. Analysis was by differential pulse anodic stripping voltammetry. No significant increase in beard Zn was found. Cd, Pb and Cu were measured simultaneously.Studies of dosing with other elements are reviewed and a generalized pool model for the deposition of ingested trace elements in hair is presented.It is suggested that the concept of hair as a monitor of endogenous elements is a simplistic one which is better modified by the pool model, the precise form of which varies with the element under consideration.