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The claim that quality of membrane fabrication is based on surface smoothness of substrate has been known since the 1960s. In this study, we propose a concept based on the interfacial interaction between the carbon molecular sieving (CMS) selective layer and the Al2O3 substrate to understand the development of the CMS membrane's micro-structure at the molecular level, especially for natural gas purification. We further compare the results with those of our previous work to determine the dominant influence on the structural development of CMS membranes, and discover a remarkable enhancement in H2/CH4 and CO2/CH4 gas pair separation performances that surpass the upper limit for polymer membranes proposed by Robeson. Permselectivity performance was found to be strongly related to substrate properties, and especially to the surface roughness. When TiO2 intermediately layer and polishing technology was used to modify the roughness of the substrate, the supported CMS membrane displayed an improvement of 364% and 144% (or 720.1 ± 16.0 and 86.3 ± 5.1) in H2/CH4 and CO2/CH4 selectivities, respectively, when compared to bare alumina-supported membranes prepared under the same conditions; the H2 permeability also increased from 537.5 to 566.1 Barrer. These results indicated an important connection between the substrate structure and the performance of the CMS membranes, providing a new understanding of the influence of each preparation parameter and a route to tailoring the structure of CMS membranes that benefit gas separation applications.

Although sound barriers have been installed along the noise-sensitive areas of the Taiwan High-Speed Rail (THSR) network, many residents complain about the noise. Therefore, this study explored noise levels along the THSR network in central Taiwan through noise measurements, noise simulations, and questionnaire survey. In addition, noise exposure population and effectiveness of regulation standards for THSR were evaluated. The results show that the measured noises were lower than the regulatory standards and the maximum noise level (Lmax) exceeded the background noise level by more than 20 dB(A). But the questionnaire survey revealed that within 100 m of the THSR track, 69% residents were highly annoyed by the noise. Such results implied that Lmax was possibly the main affect on the residents. In other words, the effectiveness of the Taiwan noise standard should be further assessed. Noise simulation software, SoundPLAN, can precisely predict the Lmax at the locations of residents, and then a relationship between Lmax and feeling of highly annoyed could be created for policy-making reference.

Appropriately allocating battery swapping stations (BSSs) encourages drivers to use battery-operated scooters (ES) for reducing air pollution. The stochastic nature of battery swapping (BS) has not been widely discussed. Also, relatively few models have been proposed to, with particular reference to the possible demand for battery swapping, optimize the BSS locations and the appropriate number of batteries provided for the users of ESs to swap depleted batteries. Hence, this study aims to develop an optimized allocation model of grid-based scooter BSS (OAMSBSS) to be used to solve the abovementioned problem. First, using Monte Carlo simulation for problem-solving operations, along with the consideration given to the traffic flow and population distribution, the stochastic BS model used to predict the demand of stochastic BS was proposed to estimate the various possible scenarios of BSD. Each scenario involved the location decisions and the time distribution for battery swapping demand. Optimizers were adopted to optimally allocate the BSS to both satisfy the BS demand scenarios and achieve the minimal BSS construction cost. The optimized locations of BSSs are considered to not only cost lower land rentals but also help a large number of drivers faced with the problem of the demand for BS services.

To realize the goal of environmental sustainability, improving energy efficiency in buildings is a major priority worldwide. However, the practical design of green building envelopes for energy conservation is a highly complex optimization problem, and architects must make multiobjective decisions. In practice, methods such as multicriteria analyses that entail capitalizing on possibly many (but in nearly any case limited) alternatives are commonly employed. This study investigated the feasibility of applying a multiobjective optimal model on building envelope design (MOPBEM), which involved integrating a building envelope energy performance model with a multiobjective optimizer. The MOPBEM was established to provide a reference for green designs. A nondominated sorting genetic algorithm-II (NSGA-II) was used to achieve a tradeoff design set between three conflicting objectives, namely minimizing the envelope construction cost (ENVCOST), minimizing the envelope energy performance (ENVLOAD), and maximizing the window opening rate (WOPR). A real office building case was designed using the MOPBEM to identify the potential strengths and weaknesses of the proposed MOPBEM. The results showed that a high ENVCOST was expended in simultaneously satisfying the low ENVLOAD and high WOPR. Various designs exhibited obvious cost reductions compared with the original architects' manual design, demonstrating the practicability of the MOPBEM.

Designing envelope configurations of office building with the low construction cost and energy consumption is a discrete optimization problem. The configuration is currently determined merely on architects’ experiences resulting in an inefficient expense or by building energy performance simulation which is time-intensive and involves complex processes. Based on an efficient regression equation to substitute complex energy simulators, this study developed an Office Building envelope Energy performance and configuration Model (OBEM) to provide envelope configurations, including construction material, sunshade type, sunshade length, window number, and window length and width for architects’ reference. Also, Tabu search, which is effective in solving discrete optimization problems, was integrated with OBEM into an Optimal OBEM decision support system (OPOBEM). The OPOBEM was applied to a real office building construction for optimizing its envelope configuration at minimum construction budget under the energy conservation regulations of green buildings. The result shows that the optimized installation of sunshade type efficiently reduces solar heat gain according to the high variation of the sunshade coefficient, thus achieves the goal of energy conservation and reduces the envelope costs. Compared with architects’ manual estimation, the optimized envelope design realizes nearly 41% budget savings, thus demonstrating the feasibility of the proposed OPOBEM.

Although carbon surfaces are generally hydrophobic, the surface oxygen-containing groups act as water molecule sorption sites, reducing the performance of carbon molecular sieving (CMS) membranes over time. In this study, a hydrophobic poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) layer was coated on the surface of PPO- or polyetherimide (PEI)-derived CMS membranes to protect against aging. The permeation properties and anti-aging characteristics of the modified CMS membranes were explored using a single gas permeability test. Furthermore, thermal annealing below the PPO's glass transition temperature was applied to the hydrophobic layer to evaluate its anti-aging effect. The results indicate that the aging of CMS membranes was also determined by the carbon matrix structure and that a smaller pore size could prevent water adsorption and O2 chemisorption. After the hydrophobic layer was post-treated with thermal annealing, the gas diffusion resistance was diminished, and the initial permeance was retained to approximately 60%, showing slight loss within the testing period.

Municipal solid waste management (MSWM) is an important environmental challenge and subject in urban planning. A sustainable MSWM strategy should consider not only economic efficiency but also life-cycle assessment of environmental impact. This study employs the fuzzy multiobjective linear programming (FMOLP) technique to find the optimal compromise between economic optimization and pollutant emission reduction for the MSWM strategy. Taichung City in Taiwan is evaluated as a case study. The results indicate that the optimal compromise MSWM strategy can reduce significant amounts of pollutant emissions and still achieve positive net profits. Minimization of the sulfur oxide (SOx) and nitrogen oxide (NOx) emissions are the two major priorities in achieving this optimal compromise strategy when recyclables recovery rate is lower; however, minimization of the carbon monoxide (CO) and particulate matter (PM) emissions become priority factors when recovery rate is higher. Implications: This paper applied the mu...

Municipal solid waste management (MSWM) is an important environmental challenge and subject in urban planning. For sustainable MSWM strategies, the critical management factors to be considered include not only economic efficiency of MSW treatment but also life-cycle assessment of the environmental impact. This paper employed linear programming technique to establish optimal MSWM strategies considering economic efficiency and the air pollutant emissions during the life cycle of a MSWM system, and investigated the correlations between the economical optimization and pollutant emissions. A case study based on real-world MSW operating parameters in Taichung City is also presented. The results showed that the costs, benefits, streams of MSW, and throughputs of incinerators and landfills will be affected if pollution emission reductions are implemented in the MSWM strategies. In addition, the quantity of particulate matter is the best pollutant indicator for the MSWM system performance of emission reduction. In particular this model will assist the decision maker in drawing up a friendly MSWM strategy for Taichung City in Taiwan.Recently, life-cycle assessments of municipal solid waste management (MSWM) strategies have been given more considerations. However, what seems to be lacking is the consideration of economic factors and environmental impacts simultaneously. This work analyzed real-world data to establish optimal MSWM strategies considering economic efficiency and the air pollutant emissions during the life cycle of the MSWM system. The results indicated that the consideration of environmental impacts will affect the costs, benefits, streams of MSW, and throughputs of incinerators and landfills. This work is relevant to public discussion and may establish useful guidelines for the MSWM policies.

Optimizations of sewer network designs create complicated and highly nonlinear problems wherein conventional optimization techniques often get easily bogged down in local optima and cannot successfully address such problems. In the past decades, heuristic algorithms possessing robust and efficient global search capabilities have helped to solve continuous and discrete optimization problems and have demonstrated considerable promise. This study applied tabu search (TS) and simulated annealing (SA) to the optimization of sewer network designs. For a case study, this article used the sewer network design of a central Taiwan township, which contains significantly varied elevations, and the optimal designs from TS and SA were compared with the original official design. The results show that, in contrast with the original design's failure to satisfy the minimum flow-velocity requirements, both TS and SA achieved least-cost solutions that also fulfilled all the constraints of the design criteria. According to th...

Nano-scale zero-valent iron (NZVI) has been shown to be suitable for remediating contaminated aquifers. However, they usually aggregate rapidly and result in a very limited migration distance that inhibits their usefulness. This study employed poly acrylic acid (PAA) and carboxymethyl cellulose (CMC) to synthesize two types of stabilized styles of NZVI with finer sizes (namely PNZVI and CNZVI). The mobility of stabilized NZVI was also demonstrated on the basis of transport in porous media. The results show that the PNZVI has a uniform particle size of 12 nm. However, tens of CNZVI particles with diameters of 1-3 nm were packed into secondary particles. Both the PNZVI and the CNZVI exhibited amorphous structures, and the stabilizer was bound to particle surfaces in the form of bidentate bridging via the carboxylic group, which could provide both electrostatic and steric repulsion to prevent particle aggregation. This study also proposes presumed stabilized configurations of PNZVI and CNZVI to reasonably illustrate their different dispersed suspension types. On the basis of the breakthrough curves and mass recovery, this study observed that the mobility of PNZVI in classic Ca(2+) concentration of groundwater was superior to CNZVI. Nonetheless, the mobility of CNZVI would be decreased less significantly than PNZVI when encountering high Ca(2+) concentrations (40 mM). Presumably, increasing the pore flow velocity would enhance the mobility of stabilized NZVI. Overall, the results of this study indicate that PNZVI has the potential to become an effective reactive material for in situ groundwater remediation.

It is expected that the simultaneous removal of acid gases and particles from flue gas, using a single process and at the same temperature, will become an economical, and thus, desirable option. Accordingly, this study investigates the potential for the utilization of a fluidized-bed adsorbent/catalyst reactor for the simultaneous removal of SO 2 and fly ash from simulated flue gas. The operating conditions for the evaluation include: (1) different pre-treatments of the adsorbent/catalyst, (2) the operating parameters of adsorption/filtration and (3) the effects of simultaneous adsorption/filtration through the fluidized-bed reactor. Based on the experimental data gathered, the Bronsted acid sites were formed on the surface of activated carbon (AC) support materials after modification with nitric or sulfuric acid and it acted as anchor. This characteristic accounts for the promotion of the effects of dispersion and adsorption of the adsorbent/catalyst. Moreover, the addition of copper facilitated the oxygen transfer of SO 2 to the carbon matrix. The concentration of SO 2 removed by the fluidized-bed adsorbent/catalyst reactor decreased from 17.9 to 14.2 mg SO 2 /g of adsorbent after exposure to a high concentration of fly ash. Therefore, an acid-pre-treatment of the adsorbent/catalyst is required to hasten the removal of SO 2 in the simulated flue gas. Our result shows that the acidic groups may facilitate the adsorbent/catalyst removal of SO 2 when there exist high concentrations of fly ash in the flue gas.

This study investigates the potential of utilizing a fluidized-bed catalytic reactor for the simultaneous removal of NO, SO2, and coal ash from simulated flue gas. The operational conditions for th...

This study investigated the potential of a fluidized-bed sorbent/catalyst reactor for the simultaneous removals of SO2 and fly ash from a simulated flue gas containing different H2O and particles. Experimental results showed that the removal efficiency of particles and SO2 was 85%−96% and 5.75−2.97 mg SO2/g, respectively, as the H2O content was 1.5−5.3%. The activities of sorbent/catalysts for simultaneous removals of SO2 and particles were inhibited by H2O and particles, and the inhibition effects increased with the content of H2O. As the H2O content increased, the particle size distribution (PSD) of fine particles shifted to the coarse particles. The results of BET analysis show that the obstruction phenomenon of the sorbent/catalyst caused by the particles was diminished with the increased content of H2O. The results showed this aggregation phenomenon of fine particles shifted to the coarse particles may cause increased water vapor content in fluidized-bed sorbent/catalyst reactor.

Injection of bimetal (Pd/Fe) nanoparticles was evidenced as a promising treatment to remediate trichloroethene (TCE) polluted groundwater. However, the particles usually aggregate rapidly and result in a very limited migration distance. This study employed poly acrylic acid (PAA) for the synthesis of stable bimetal nanoparticles (SBN) by selecting appropriate PAA molecular weight and dosage to reduce particle aggregation. In addition, this study elucidated the SBN stabilization mechanism by analyzing morphology and characteristics. The results of TCE dechlorination and SBN stabilization experiments indicate that the bimetal nanoparticles modified with PAA250K exhibit better reactivity and stability characteristics than did other such nanoparticles. The SBN bind chemically onto PAA250K via the carboxylic group and bidentate pattern bridging, which could provide both electrostatic and steric repulsion to prevent particle aggregation. Therefore, the SBN exhibited a higher dechlorination effect than did bare bimetal. The morphology of SBN shown in the transmission electron microscopy (TEM) images exhibits capsule-like and wire-like structures instead of a single particle dispersed in the slurry. The results of this work can preliminarily elucidate the SBN's morphology, dispersion, and size distribution.

In 1995, Taiwan's Environmental Protection Administration (EPA/TW) instituted a policy of levying emission taxes on polluters in order to combat the rampant national issue of pollution. Since that time, pollution control strategies, tightening exhaust emission standards for industry, improvements in fuel quality, and new stricter vehicle emission standards, etc., have been implemented. This study evaluates the effectiveness of these measures and examines the improvement of Taiwan's air quality. In this paper, we conduct a detailed analysis of change in the concentrations of pollutants (SO2, NOx and particulate matter [PM]) between two three-year periods (from 1996 to1998 and from 2000 to 2002). The pollution levels were generally lower in the latter period. Concentrations at 14 EPA/TW stations in central Taiwan were simulated and source apportionment analyses in three of Central Taiwan's largest cities were conducted using a trajectory transfer-coefficient air quality model. Correlation coefficients (r) between simulations and observations for the monthly means of the concentrations of SO2, NOx, PM2.5 and PM10 during the study periods at the 14 stations are 0.56, 0.63, 0.70 and 0.31, respectively. The sulfur control policy greatly reduced SO2 concentration island-wide, a stringent emission standard put into place for gasoline vehicles reduced NOx concentration along highways, and an emissions tax placed on construction sites, as well as a regular program for road-dust sweeping, reduced primary particulate matter. Among all of the pollution abatement policies implemented, the most effective method for reducing PM2.5 concentrations in the three largest cities involved the reduction of fine ammonium sulfate aerosols from point sources (56–63% of net PM2.5 reduction). The next largest reduction was attributed to a diminishment in primary PM2.5 emanating from point sources (27–56% of net PM2.5 reduction). Secondary particulate matter, especially sulfate, was reduced from distances up to 150 km leeward of major pollution point sources such as Taichung Power Plant.

This study analyzed the spatial characteristics of urban environmental noise by using noise maps produced at 345 noise monitoring stations in Tainan, Taiwan. Noise data were collected at varying intervals: morning, afternoon, and evening in both summer and winter. The spatial distributions of the noise levels during each time interval were evaluated and visualized by geographic information systems. The analytical results indicated that the highest and lowest average noise levels were 69.6 dB(A) and 59.3 dB(A) during summer mornings and winter evenings, respectively. Comparison of monitored noise levels with regulatory standards revealed that noise standard violations, which usually occur on summer evenings, are as high as 23 dB(A). Furthermore, the results of noise exposure analysis showed that over 90% of the Tainan City population are exposed to unacceptable noise as defined by US Department of Housing and Urban Development. The findings of this study show that noise maps can be useful for investigating noise in urban environments.

A methodology based on the integration of a seismic-based artificial neural network (ANN) model and a geographic information system (GIS) to assess water leakage and to prioritize pipeline replacement is developed in this work. Qualified pipeline break-event data derived from the Taiwan Water Corporation Pipeline Leakage Repair Management System were analyzed. "Pipe diameter," "pipe material," and "the number of magnitude-3( + ) earthquakes" were employed as the input factors of ANN, while "the number of monthly breaks" was used for the prediction output. This study is the first attempt to manipulate earthquake data in the break-event ANN prediction model. Spatial distribution of the pipeline break-event data was analyzed and visualized by GIS. Through this, the users can swiftly figure out the hotspots of the leakage areas. A northeastern township in Taiwan, frequently affected by earthquakes, is chosen as the case study. Compared to the traditional processes for determining the priorities of pipeline replacement, the methodology developed is more effective and efficient. Likewise, the methodology can overcome the difficulty of prioritizing pipeline replacement even in situations where the break-event records are unavailable.

This work focused on developing an approach for prioritizing the order of pipe replacement in a water distribution system (WDS) using a seismic-based artificial neural network (ANN). The q...

Developing efficient sound absorption materials is a relevant topic for large scale structures such as gymnasiums, shopping malls, airports and stations. This study employs artificial neural network (ANN) algorithm to estimate the sound absorption coefficients of different perforated wooden panels with various setting combinations including perforation percentage, backing material and thickness. The training data sets are built by carrying out a series of experimental measurements in the reverberation room to evaluate the sound absorption characteristics of perforated wooden panels. A multiple linear regression (MLR) model is also developed for making comparisons with ANN. The analytical results indicate that the ANN exhibits satisfactory reliability of a correlation between estimation and truly measured absorption coefficients of approximately 0.85. However, MLR cannot be applied to nonlinear cases. ANN is a useful and reliable tool for estimating sound absorption coefficients estimation.

This study measured vertical distributions of ozone, sulfur dioxide, nitrogen oxide, carbon monoxide, six biogenic-related volatile organic compounds, wind vector, humidity and temperature within the Planetary Boundary Layer (PBL) below 1200 m using a tethered balloon sounding system at a downwind rural site in the Taichung Basin, Taiwan, during the 2002 summer. During ozone episodes, both nocturnal inversion and valley-mountain wind circulation were stronger than those during non-episode days. The observed vertical distributions of these pollutants indicate that the concentrations of carbon monoxide, nitrogen monoxide and biogenic volatile organic compounds decreased as the height increased. Conversely, the highest ozone concentrations were measured during early afternoon at heights of 100-600 m above ground level. Notably, these high ozone concentrations were normally accompanied by relatively higher concentrations of nitrogen dioxide and sulfur dioxide, but not carbon monoxide. From emission inventory, trajectory analysis and statistical analysis, all suggest that high-stack point sources have an important role in causing the summer ozone episodes. This suggestion is supported by 11-y summer data at three stations in the Basin. In addition, it is found that part of the early-afternoon surface ozone was from ozone stored aloft in the residue layer at heights above the nocturnal boundary layer of the preceding night.

This study developed cost functions applicable to open-cut and jacking methods, which are construction techniques of sewer systems often used in gravel strata. The cost functions obtained by linear regression, expressed as functions of pipe size and excavation depth, were used to estimate the construction costs of sewer systems. Data for several real sewer system construction projects in Taiwan were investigated to verify the accuracy of the cost functions. Analytical results revealed that estimated and real costs deviated by less than 5%, a difference less than that for cost functions currently utilized in Taiwan. The cost functions developed in this study are more realistic, practical, accurate, and easy to use than existing functions. As the Taiwanese government is now implementing the building operator transfer policies for sewer system construction, the proposed cost function should prove to be a very useful tool, allowing both government and contractors to quickly estimate sewer construction budgets.

Although regionalization policies have been proven as good strategies for municipal solid waste (MSW) management in previous studies, the optimal allocation of the waste stream is significantly affected by several influential factors, thus further investigation of the impacts of these factors on regional MSW management strategies is necessary. This study demonstrated the impacts of waste-to-electricity transformation coefficient (WETC) of incinerators and the fluctuation of unit tipping fees on the regional MSW flow/allocation of the Taipei metropolitan area from practical and economic perspectives. Real-world data and linear programming were used to obtain the least-cost alternatives under different scenarios. Analytical results indicated some treatment facilities had geographic superiority and their priorities changed when actual WETCs of incinerators were considered. Treatment facilities located at weighted centers were identified. The allocation of MSW among incinerators and landfills is affected by fluctuation of unit tipping fees within a certain range. Treatment facilities sensitive to the changes in unit tipping fees were also identified. Regression equations were also established that can estimate the cost items of MSW management scenarios with different unit tipping fees. The results of this study are very useful for daily basis regulation of MSW administration.

The concentration of polycyclic aromatic hydrocarbons (PAHs) in the ambient air from a massive open burning of joss paper was simultaneously measured at an open-burning site (OS) and a downwind site (DS) from 6 to 8 August 2006. A total of 16 major PAHs (particle-bound and gas-phase) concentrations were extracted by the Soxhlet analytical method and analyzed by gas chromatography. The dominant PAHs of the total mass of the organic compound at both the sampling sites were low-molecular-weight species. Further, the results showed that the start burning/end burning-dominant PAH concentration ratios at the OS and DS were 10 and 6.2, respectively. Diagnostic ratios were also used in this study to characterize and identify the PAH emission sources. The results suggest that the characterization of air pollutants emitted from open-burning joss paper lies between furnace-burning joss paper and wood combustion.

The optimization problems of water distribution networks are complex, multi-modal and discrete-variable problems that cannot be easily solved with conventional optimization algorithms. Heuristic algorithms such as genetic algorithms, simulated annealing, tabu search and ant colony optimization have been extensively employed over the last decade. This article proposed an optimization procedure based on the scatter search (SS) framework, which is also a heuristic algorithm, to obtain the least-cost designs of three well-known looped water distribution networks (two-loop, Hanoi and New York networks). The computational results obtained with the three benchmark instances indicate that SS is able to find solutions comparable to those provided by some of the most competitive algorithms published in the literature.

Municipal solid waste (MSW) management is a major concern for highly urbanized societies. Among proposed MSW management systems, regionalization programs generally have received considerable attention. This study analyzes real-world operational data to assess different MSW management policies, especially regionalization strategies, and their impact on MSW management systems in the Taipei metropolitan area. Linear programming is also used to identify the minimum costs sustained by each policy. The linear programming results show that regionalization programs are more economical and also improve incinerator operation efficiency. Sensitivity analysis indicates that the minimum treatment requirement of incinerators is a very sensitive influence on the MSW flows distributed through the entire region. The MSW of several "sensitive" administrative districts will be allocated to different treatment facilities according to different management strategies. A list of preferential sequences of MSW treatment and disposal facilities can also be identified by the model presented in this study. The results of this study may provide a useful tool for aiding decision-making related to real-world MSW management problems.

Zero-plane displacement and aerodynamic roughness measurements were conducted using a tethersonde system in the third largest city in Taiwan. A method for determining the roughness under unstable conditions was developed. The resulting aerodynamic roughness and sensible heat flux were found to be very sensitive to a prescribed zero-plane displacement value. To minimize the uncertainty, the Bowen Ratio method was used to choose the correct sensible heat flux and zero-plane displacement values. Although the study site has the highest building height reported in the literature, its aerodynamic roughness value was determined to be 2.1 m, lower than values commonly cited for urban areas in the air quality community, while the zero-plane displacement value was found to be 35 m, the highest value reported in the literature.

Using a tethered balloon, vertical air pollutant concentrations (CO, SO2, NO, NO2 and O3) were measured in central Taiwan during field campaigns in the winters of 1999 and 2001. Modified novel lightweight sampling equipment was used to take samples at heights of 1, 13, 100, 300, 500 and 1200 m. A balloon was launched every 3 h and in total there were 133 flights during the three campaigns. The data were collected in order to examine the temporal and vertical variations of pollutants. The average daytime profiles showed greater vertical convection mixing in unstable circumstances. The characteristics of shapes and time behavior of profiles are reported. Except for a slight decrease near the ground and strong photochemical reactions at clear daytime, titration of O3 by NO was observed at all altitudes in the atmospheric boundary layer during these campaigns. Ground level ozone may be contributed by downward mixing from above. A fair correlation appeared between the maximum ozone concentration at the surface during the daytime ( C 0 Max ) and average ozone concentration above the NBL ( C a NBL ). A linear regression equation is shown as C 0 Max =29+0.91 C a NBL .

This paper presents a preliminary study for the evaluation of transport-related air pollution situations in an urban area. The authors utilize a geographic information system (GIS) which integrates a vehicle emission model, pollutant dispersion model, backward trajectory model and related databases to estimate the emissions and spatial distribution of traffic pollutants in Taichung, Taiwan, ROC. The model not only can analyze the current pollution situations, but also can predict the emissions influenced by changes in specific traffic conditions or management policies. The results show that there are higher CO emissions around downtown areas in Taichung City, and the areas along Highway No.1 sustain higher NOx, SOx and TSP pollutions. Although the segment length of Highway No.1 within Taichung City is not very long, it contributes a significant portion of total suspended particulate (TSP), nitrogen oxides (NOx), and sulfur oxides (SOx) emissions to this area. Furthermore, predictions of several hypothetical scenarios indicate that the major effect of upgrading motorcycles is the reduction of TSP emission by more than 10%, while increasing average traffic speed of city roads may reduce more than 14% of CO emissions.

We developed new solutions for soil vapor extraction from a finite horizontal well in unsaturated zones by Fourier and Laplace transforms. These solutions may be applied for problems with or without laterally impervious bounds and for covered, uncovered or leaking ground surface conditions. However, the solution for the problems with laterally impervious bounds is expressed in series form. To attain good accuracy, the required number of terms for the series solution may depend on the ratio of width and depth of the problem domain. Further, with the dimensionless permeability, kD (the ratio of permeability for the leakage layer and that for the unsaturated zone) and dimensionless depth, fD (the ratio of the leakage layer depth and the unsaturated soil depth), we may find lower and upper limit values of the ratio of kD and fD for the problems representing covered and uncovered surface condition, respectively.

Municipal solid waste management (MSWM) is an important, practical and challenging environmental subject. The processes of a MSWM system include household collection, transportation, treatment, material recycling, compost and disposal. A regional program of MSWM is more complicated owing to the involvement of multi-municipality and multi-facility issues. Therefore, an effective decision support system capable of solving regional MSWM problems is necessary for decision-makers. This article employs linear programming techniques to establish a MSWM decision support system (MSWM-DSS) that is able to determine the least costs of regional MSWM strategies. The results of investigating a real-world case in central Taiwan indicate that a regional program is more economical and efficient. For the redeployment of MSW streams, the relatively least cost of operation for the MSWM system can still be achieved through the re-estimation of the MSWM-DSS. This tool and results are useful for MSWM policy-making in central Taiwan.

A ground-water management model using a nonlinear programming algorithm was developed to find the minimum cost design of the combined pumping and treatment components of a pump-and-treat remediation system and includes the fixed costs of system construction and installation as well as operation and maintenance. The fixed-cost terms of the objective function are incorporated into the nonlinear programming formulation using a penalty coefficient method. Results of applying the model to an aquifer with homogeneous hydraulic conductivity show that a combined well field and treatment process model that includes fixed costs has a significant impact on the design and cost of these systems, reducing the cost by using fewer, larger-flow-rate wells. Previous pump-and-treat design formulations have resulted in systems with numerous, low-flow-rate wells due to the use of simplified cost functions that do not exhibit economies of scale or fixed costs. Two example aquifers with heterogeneous conductivity fields were al...

An optimal aquifer remediation design model employing a nonlinear programming algorithm was developed to find the minimum cost design of a pump-and-treat aquifer remediation system. The mixed-integer nonlinear programming model includes the discontinuous fixed costs of system construction and installation as well as operation and maintenance. The fixed cost terms in the objective function have been approximated by continuous functions of the decision variables using a polynomial penalty coefficient method resulting in a nonlinear programming formulation of an otherwise mixed-integer nonlinear programming model. Results of applying the new polynomial penalty coefficient method to an example design problem show that a combined well field and treatment process model hat includes fixed costs has a significant impact on the design and cost of aquifer remediation systems, reducing system costs by using fewer, larger flow rate wells. Previous pump-and-treat design formulations have resulted in systems with numerous, low flow rate wells due to the use of simplified cost functions that do not exhibit economies of scale or fixed costs. The polynomial penalty coefficient method results were compared to two alternative approximate mixed-integer nonlinear programming methods for solving optimal quifer remediation design problems, the pseudo-integer method and the exponential penalty coefficient method. The polynomial penalty coefficient method obtains the same solutions and performs as well as or better than the exponential penalty coefficient method. The polynomial penalty coefficient method almost always results in better, less expensive designs and requires significantly less computer time than the pseudo-integer method.

Groundwater simulation models have been incorporated into a genetic algorithm to solve three groundwater management problems: maximum pumping from an aquifer; minimum cost water supply development; and minimum cost aquifer remediation. The results show that genetic algorithms can effectively and efficiently be used to obtain globally (or, at least near globally) optimal solutions to these groundwater management problems. The formulation of the method is straightforward and provides solutions which are as good as or better than those obtained by linear and nonlinear programming. Constraints can be incorporated into the formulation and do not require derivatives with respect to decision variables as in nonlinear programming. More complicated problems, such as transient pumping and multiphase remediation, can be formulated and solved using this method. The computational time required for the solution of genetic algorithm groundwater management models increases with the complexity of the problem. The speedup attainable by solving genetic algorithm problems on massively parallel computers is significant for problems where the simulation time required to complete each generation is high. 47 refs., 9 figs., 5 tabs.

This study employed simulated annealing (SA) to optimize minimum-cost design of sewer network. A sewer network design which contains significantly varied elevations was used as a case study. The results show that SA is able to achieve least-cost solutions which also fulfill all the constraints of design criteria. Based on the average performance of 200 trials, SA exhibits robustness and efficiency for solving sewer network system optimization problems.

This study developed cost functions, which were expressed as functions of pipe sizes and excavation depths, applicable to open cut and jacking techniques for construction of sewer systems. Data for several real sewer system construction projects in Taiwan were investigated to verify the accuracy of the cost functions. The cost functions developed in this study are more realistic, practical, accurate and easy to use than existing functions.

The optimization of water distribution networks are complex, multi-modal and discrete-variable problems that cannot be easily solved with conventional optimization algorithms. This study adopts ant algorithm (AA), immune algorithm (IA), and scatter search (SS) which are all evolutionary computing techniques to avoid the entrapments by local optimal solutions, to obtain the leastcost designs of water distribution networks. One benchmark water distribution network optimization problems is used as a case study. Comparisons of the results of this study with relevant literature data indicate that AA and SS are able to find solutions better than those provided by some of the most competitive algorithms published in the literature. Furthermore, the results of the success rate evaluation indicate that AA can 100% successfully achieve the global optimum.

Spatial noise characteristics of Tainan City in Taiwan were investigated in this study by noise mapping. Noise data were collected from 345 noise monitoring stations. The spatial distributions of the noise levels during different time interval were evaluated and visualized by geographic information systems. Noise standard violations as high as 23dB(A) were frequently observed on summer evenings. Over 90% of the Tainan City population are exposed to unacceptable noise as defined by US Department of Housing and Urban Development. It can be concluded that noise mapping is useful for environment management of urban noise.

This paper describes the methodology and application of an immune algorithm (IA) scheme tailor-made for the EPANET for simultaneously optimizing the injection rates and scheduling of chlorine booster stations under the unsteady state of a water distribution network system (WDNS). The objective of this study is to initiate a total chlorination dose to satisfy the minimum and maximum required chlorine residual at every demand node in a WDNS while minimizing the chlorine consumption as much as possible. The decision variables are the scheduling of the mass injection rate at the booster node in the WDNS segments. The evaluation results confirm the potential of IA in solving the scheduling of booster disinfection optimization problems.

Large-scale open burning of joss paper is an important ritual practice for deity worshipping during Buddhist and Taoist festivals. Since Buddhism and Taoism are two of the most popular religions in Chinese societies and some Asian countries, the impact of joss paper burning on the air quality needs further investigation. This study explores the concentrations of polycyclic aromatic hydrocarbons (PAHs) in ambient air during one of the most important festivals, in which large-scale burning of joss paper occurs in temples and in people's houses. The PAH concentrations were measured simultaneously at a temple site and a background site during both the festival and non-festive (ordinary) periods. Each ambient sample was extracted by the Soxhlet analytical method (for both particle-bound and gas-phase) and analyzed with gas chromatography. Experimental results indicate that the total PAH concentration during the festival period is approximately 4.2 times higher than that during the ordinary period (5384 ng m−3 vs. 1275 ng m−3). This study also employed statistical methods including diagnostic ratios and principal component analysis (PCA) to identify the possible PAH emission sources. Joss paper burning and vehicular emissions are identified as the principal sources of airborne PAHs during the large-scale open-burning event. The results of this work provide useful information for public awareness concerning PAH emission from the open burning of joss paper.