As a matter of expediency, most existing corporate-based urban networks can only be quantitatively measured by either counting the number of linkages or calculating the product of estimated service values. However, th...As a matter of expediency, most existing corporate-based urban networks can only be quantitatively measured by either counting the number of linkages or calculating the product of estimated service values. However, the impreciseness arising due to the limits of quantitative analysis may prove fatal to studies about non-market economies like China. Employing the capital investment dataset as an example, we build a capital-weighted intervention network as well as an unweighted control network to carry out an examination of the quantitative validity in China’s corporate-based urban network analysis. Both the overall spatial pattern and top city-dyads within the capital-weighted network witness Beijing, as the most dominant city, overshadow the performance of the others, and the unweighted network shows multilateral interactions between China’s top cities including Beijing, Shanghai, Shenzhen, and Guangzhou. To further interpret the noticeable differences, we divide the overall network into two subnetworks, inferred by focusing on state-owned enterprises(SOEs) and private enterprises. The results show that the public and private sectors have separately created vastly different subnetworks in China and that SOEs play a much more significant role in terms of capital. Besides fresh insights into China’s urban network, this study provides a cautionary tale reminding researchers of the essentiality and complexity when making a quantitative distinction between different linkages.展开更多
Life cycle assessment (LCA) is one of the most widely used methods of decision support. However, few studies have examined whether stakeholders prefer midpoint or endpoint approaches. In this regard, the present study...Life cycle assessment (LCA) is one of the most widely used methods of decision support. However, few studies have examined whether stakeholders prefer midpoint or endpoint approaches. In this regard, the present study examines the attitudes toward urban solid waste management, environmental issues, and scenario evaluations by using midpoint and endpoint interpretations of LCA results. This study introduces three types of social groups that typically respond to environmental conflicts: the individualist, hierarchist, and egalitarian groups. Although residents are likely to recognize global impacts as the most important issue, their view is likely to change depending on system and avoided emissions. Consistent with the Seoul Metropolitan Area’s new policy designed to increase the incineration ratio, almost half of all respondents preferred the scenario. Noteworthy is that the respondents’ preference for midpoint and endpoint decision-making tools is not consistent with that in previous studies. Most of the respondents indicated that the midpoint approach would be better in evaluating environmental systems.展开更多
Ozonation of synthetic water containing a type of endocrine disruptor-di-n-butyl phthalate （DBP） was examined. Key impact factors such as pH, temperature, ionic strength, ozone dosage and initial DBP concentration w...Ozonation of synthetic water containing a type of endocrine disruptor-di-n-butyl phthalate （DBP） was examined. Key impact factors such as pH, temperature, ionic strength, ozone dosage and initial DBP concentration were investigated. In addition, the activities of radicals on uncatalysed and catalysed ozonation were studied. The degradation intermediate products were followed and the kinetic of the ozonation were assessed as well. Results revealed that ozonation of DBP followed two mechanisms. Firstly, the reaction rate of direct ozonation was slower at lower pH, temperature, and ionic strength. Secondly, when these factors were increased for indirect radical reaction, higher percentage of DBP was removed with the increase of the initial ozone dosage and the decrease of the initial DBP concentration. In addition, tea-butanol, humic substances and Fe（Ⅱ） affected DBP ozonation through the radical pathway. It was determined that ozonation was restrained by adding tea-butanol for its radical inhibition effect. Furthermore, humic substances enhanced the reaction to some extent, but a slight negative effect would be encountered if the optimum dosage was exceeded. As a matter of fact, Mn（Ⅱ） affected the ozonation by ＂active sites＂ mechanism. In the experiment, three different kinds of intermediate products were produced during ozonation, but the amount of products for each one of them decreased as pH, temperature, ionic strength and initial ozone dosage increased. A kinetic equation of the reaction between ozone and DBP was obtained.展开更多
An estrogen receptor （ER）/androgen receptor （AR） ligand competitive binding assay （ER/AR-binding assay） and chemical analyses were used to evaluate the endocrine disrupting chemicals （EDCs） behavior of two mun...An estrogen receptor （ER）/androgen receptor （AR） ligand competitive binding assay （ER/AR-binding assay） and chemical analyses were used to evaluate the endocrine disrupting chemicals （EDCs） behavior of two municipal wastewater treatment plants （WWTPs） （K and S）. In the influents, estrone （E 1）, androsterone （A）, androstenedione （AD）, BPA （bisphenol A）, NP （nonylphenol） and daidzein （DZ） were detected in high amounts with subsequent 24 h-average concentrations of 350, 1000, 29, 1300, 3900, and 5700 ng/L in K-WWTP and of 310, 620, 59, 1600, 2600, and 8400 ng/L in S-WWTP. The estrogenic （androgenic） activity as 17β-estradiol （E2） equivalents （EEQ） or testosterone （Te） equivalents （TEQ） was consequently 620 ng E2/L （570 ng Te/L） and 580 ng E2/L （800 ng Te/L） for the two WWTPs. The removal efficiencies of the above mentioned sole target chemicals were 51%-100% for K-WWTP and 55.6%-100% for S-WWTP. The removal efficiencies of EEQ were about 73% for both WWTPs, while the removal efficiencies of TEQ were 62.1% for K-WWTP and 98.4% for S-WWTP. In addition, chemical-derived EEQ were about 1.2%-52.4% of those by ER-binding assay for K-WWTP and the corresponding ratios were 1.3%-83.3% for S-WWTP, while chemical derived TEQ were less than 3% of values measured by the AR-binding assay for both WWTPs.展开更多
The development and rapid usage of numerical codes for fluid-structure interaction(FSI) problems are of great relevance to researchers in many engineering fields such as civil engineering and ocean engineering. This m...The development and rapid usage of numerical codes for fluid-structure interaction(FSI) problems are of great relevance to researchers in many engineering fields such as civil engineering and ocean engineering. This multidisciplinary field known as FSI has been expanded to engineering fields such as offshore structures, tall slender structures and other flexible structures applications. The motivation of this paper is to investigate the numerical model of two-way coupling FSI partitioned flexible plate structure under fluid flow. The adopted partitioned method and approach utilized the advantage of the existing numerical algorithms in solving the two-way coupling fluid and structural interactions. The flexible plate was subjected to a fluid flow which causes large deformation on the fluid domain from the oscillation of the flexible plate. Both fluid and flexible plate are subjected to the interaction of load transfer within two physics by using the strong and weak coupling methods of MFS and Load Transfer Physics Environment, respectively. The oscillation and deformation results have been validated which demonstrate the reliability of both strong and weak method in resolving the two-way coupling problem in contribution of knowledge to the feasibility field study of ocean engineering and civil engineering.展开更多
The effectiveness of chlorine and ultraviolet light at inactivating indigenous microbes in primary treated wastewater was examined in this study. The inactivation rates for somatic colipahge and F-specific bacteriopha...The effectiveness of chlorine and ultraviolet light at inactivating indigenous microbes in primary treated wastewater was examined in this study. The inactivation rates for somatic colipahge and F-specific bacteriophage were less than 2.5 log and 1 log, respectively, at either free chlorine doses of 6, 15 mg/L and 30 mg/L after 30 minutes contact time. However, E. coli and total coliforms were susceptible to chlorination and inactivated more than 4 log within first 15 minutes of contact time at any chlorine dosage tested. In contrast, the inactivation of bacteriophage was increased when increasing UV fluence. At the same disinfection effectiveness against E. coli, UV disinfection was more effective than chlorination against F-specific bacteriophages.展开更多
Minimizing water loss in water supply networks is one of the objectives for protecting water resources. Currently, the large amount of water loss is mainly due to leakage of the pipeline network. The leaking of pipe c...Minimizing water loss in water supply networks is one of the objectives for protecting water resources. Currently, the large amount of water loss is mainly due to leakage of the pipeline network. The leaking of pipe can be caused by incorrect construction, impacted by external forces, or corroded pipe material and aging. Therefore, to control and predict the cracking area on pipe, it is necessary to collect data about pipe conditions, approve the solution of technology improvement and define the ability of pipe capacity from setting up to the first preparing time. This paper will demonstrate how to evaluate corrosion pipe under the age of pipe and the impact level of internal pressure pipe at different times, and will put forward solution of effective leaking management on water supply network.展开更多
In Tokyo, as residential areas exist in the urban areas and are composed of areas owned by individual land owners, basically spatial changes are brought by redevelopments of each sites conducted by individual circumst...In Tokyo, as residential areas exist in the urban areas and are composed of areas owned by individual land owners, basically spatial changes are brought by redevelopments of each sites conducted by individual circumstances and motivations. Continuous redevelopments and spatial changes can be found dispersedly in areas. Once the spatial change in a certain site occurred in an area as a building, it will be contained in the built environment of the residential area which is defined by residents, planners and designers who will take part in the following spatial changes. In Tokyo, public transportation facilities are well developed, and residents＇ daily life involves activities such as a slow walking and bicycle, etc. around the place of residence near the public transportation hubs, each living territories are formed in this kind of manner. Considering the maintenance of spatial value in residential areas while understanding transformation of visual local environment in residential areas which focuses on appearance of each spatial change in an area of street will be of significant importance. In this paper, the authors try to describe interactions of spatial changes in existing urban residential areas focusing on utility of players who might take part in the following spatial changes and the method of discrete choice model.展开更多
We analyzed the determinants of building bridges after comparing bridge islands and non-bridge islands.In addition,we examined the population change before and after the bridge building and the factors influencing the...We analyzed the determinants of building bridges after comparing bridge islands and non-bridge islands.In addition,we examined the population change before and after the bridge building and the factors influencing the change.As a result,a remote island with high cost-effectiveness was selected and bridged.The early bridge was built in remote islands with fragile social infrastructure,and the outflow of population was suppressed owing to the improvement in standard of living by securing the medical care and education available in the bridge destination.However,around the year 2000,there are few remote islands where the changes in populations are influenced after a bridge was built.展开更多
Facing challenges of population decline and fiscal austerity,Japan has implemented a series of initiatives to promote public-private partnerships(PPP)to ensure the sustainability of urban parks and revitalize urban sp...Facing challenges of population decline and fiscal austerity,Japan has implemented a series of initiatives to promote public-private partnerships(PPP)to ensure the sustainability of urban parks and revitalize urban spaces.These initiatives,while alleviating the government’s financial burdens on parks,have also raised concerns about the potential erosion of publicness and public interests resulted from the commercialization of public assets.This paper reviews the evolution of Japan’s urban park management system after World War II—including three phases of being purely public goods,initiating marketization,and diversifying management entities.The functions of parks have continuously enriched,and the construction,management,and operational modes have shifted from government-led towards multi-stakeholder participation,along with expanded funding sources.By examining the PPP types,driving forces,implementation mechanisms and challenges in urban park management,this paper points out that,in different eras and social contexts,the Japanese government has kept adjusting its role to maximize public interests.This has proactively updated the implications of publicness in infrastructure like urban parks,from a post-war opposite of publicness versus privateness on ownership,to the participation of private capital for a higher efficiency,and finally to a community for a stronger regional competitiveness.The reforms of urban park management system in Japan offer significant lessons and insights for urban infrastructure management in other countries and regions.展开更多
Based on an in-depth survey of different typical areas that are selected in different regions and at different levels, this paper identifies the general characteristics of China's urbanization, the impacts that ec...Based on an in-depth survey of different typical areas that are selected in different regions and at different levels, this paper identifies the general characteristics of China's urbanization, the impacts that economic development driven by both exogenous and endogenous engines has on the spatial pattern of urbanization, and the two urbanization paths:gradient development and hierarchal advancement. By analyzing such factors as population growth, population mobility, and economic and industrial development, it sums up five spatial patterns for future urbanization development trends. Through the analyses on the three aspects:whereabouts of the present 260 million migrant workers and their families, whereabouts of the new-born population and new working-age rural population, and the migrant scale of the existing agricultural labors moving to non-agricultural industries, this paper predicts that China's urbanization rate will slow down in the next five to ten years, and will reach about 65 percent in around 2030. On the basis of the analyses, it puts forward that "Five-Six-Eleven" regional pattern of urbanization should be established to guide the overall strategy for spatial pattern optimization. To optimize the spatial pattern of urbanization, it proposes specific strategies including coordinated development of large, medium-sized, and small cities, and small towns, as well as urbanization development strategies of differentiation according to different classes and regions.展开更多
This article aims to describe the influence of diffuse pollution on the temporal and spatial characteristics of natural organic matter （NOM） in a stratified dam reservoir, the Daecheong Dam, on the basis of intensiv...This article aims to describe the influence of diffuse pollution on the temporal and spatial characteristics of natural organic matter （NOM） in a stratified dam reservoir, the Daecheong Dam, on the basis of intensive observation results and the dynamic water quality simulation using CE-QUAL-W2. Turbidity is regarded as a comprehensive representation of allochothonous organic matter from diffuse sources in storm season because the turbidity concentration showed reasonable significance in a statistical correlation with the UV absorbance at 254 nm and total phosphorus. CE-QUAL-W2 simulation results showed good consistency with the observed data in terms of dissolved organic matter （DOM） including refractory dissolved organic carbon （RDOC） and labile DOC and also well explained the internal movement of constituents and stratification phenomenon in the reservoir. Instead turbidity and NOM were related well in the upper region of the reservoir according to flow distance, gradually as changing to dissolved form of organic matter, RDOM affected organic matter concentration of reservoir water quality compared to turbidity. To control the increase of soluble organic matters in the dam reservoir, appropriate dam water discharge gate operation provided effective measurement. Because of the gate operation let avoid the accumulation of organic matter within a dam reservoir by shorten of turbid regime retention time.展开更多
Microcystis panniformis is a bloom forming species with flat panniform-like colonies. This species was recently found in Lake Taihu, China. To specifically characterize M. panniformis based on isolated strains, morpho...Microcystis panniformis is a bloom forming species with flat panniform-like colonies. This species was recently found in Lake Taihu, China. To specifically characterize M. panniformis based on isolated strains, morphological examination on colonial transition and genetic examination are needed. Three M. panniformis strains isolated from a water bloom sample in Lake Taihu were characterized by molecular analysis and toxin quantification. Phylogenetic analysis based on both 16S rRNA gene and internal transcribed spacer(ITS) between 16S and 23S rRNA genes were performed and compared to facilitate easy identification of the species.Relatively high similarities(98%–99%) were shown in 16S rDNA sequences between the strains of M. panniformis and those of other Microcystis species, whereas the similarities for ITS sequences were 88%–95%. In the phylogenetic tree based on the 16S rDNA sequences, the M. panniformis and M. aeruginosa strains were intermixed together with no clear division,whereas all of the M. panniformis strains were clustered together in a single clade based on the ITS sequences based phylogenyetic tree. The mcyE gene was detected in all three strains, and microcystin was determined by high-performance liquid chromatography. The molecular detection and toxin production of M. panniformis strains are of great significance for the environmental risk assessment of Microcystis blooms.展开更多
Anion exchange resins （AERs） with different properties were evaluated for their ability to remove dissolved organic matter （DOM） and bromide, and to reduce disinfection by-product （DBP） formation potentials of w...Anion exchange resins （AERs） with different properties were evaluated for their ability to remove dissolved organic matter （DOM） and bromide, and to reduce disinfection by-product （DBP） formation potentials of water collected from a eutrophic surface water source in Japan. DOM and bromide were simultaneously removed by all selected AERs in batch adsorption experiments. A polyacrylic magnetic ion exchange resin （MIEX） showed faster dissolved organic carbon （DOC） removal than other AERs because it had the smallest resin bead size. Aromatic DOM fractions with molecular weight larger than 1600 Da and fluorescent organic fractions of fulvic acid- and humic acid-like compounds were efficiently removed by all AERs. Polystyrene AERs were more effective in bromide removal than polyacrylic AERs. This result implied that the properties of AERs, i.e. material and resin size, influenced not only DOM removal but also bromide removal efficiency, MIEX showed significant chlorinated DBP removal because it had the highest DOC removal within 30 rain, whereas polystyrene AERs efficiently removed brominated DBPs, especially brominated trihalomethane species. The results suggested that, depending on source water DOM and bromide concentration, selecting a suitable AER is a key factor in effective control of chlorinated and brominated DBPs in drinking water.展开更多
Diarrheal diseases can be transmitted via both primary infection due to exposures to contaminated materials from the environment and secondary infection due to person- to-person contacts. Usually, the importance of se...Diarrheal diseases can be transmitted via both primary infection due to exposures to contaminated materials from the environment and secondary infection due to person- to-person contacts. Usually, the importance of secondary infection is empirically assessed by fitting mathematical models to the epidemic curves. However, these empirical models may not be applicable to other epidemic cases because they are developed only for the target epidemics and they don＇t consider the detail routes of infection. In our previous study, we developed a theoretical model taking into account the various routes of infection that commonly occur in households （e.g., shaking hands, food handling, and changing diapers）. This model was made flexible and applicable to any epidemics by means of adjusting model parameters. In this study, we proposed a new index ＂Vulnerability indicator to secondary infection （VISI）＂, which expressed a ratio of secondary infection to primary infection risks and calculated this index in a simulated norouirus （NOV） epidemic that involved I0,000 households. The results demonstrated that households composed of more than three members including infant（s） had much higher levels of VlSl （5-45） than two-member-households with VlSI （0.1-4）. These results concluded that the infants were likely to be a hub of secondary infections in highly dense families and therefore careful handling of diapers was deemed indispensible in such families to effectively control the secondary infections.展开更多
To develop a sound post-treatment process for anaerobically-digested strong wastewater,a novel natural treatment system comprising two units is put forward.The first unit,a trickling filter,provides for further reduct...To develop a sound post-treatment process for anaerobically-digested strong wastewater,a novel natural treatment system comprising two units is put forward.The first unit,a trickling filter,provides for further reduction of biochemical oxygen demand and adjustable nitrification.The subsequent soil–plant unit aims at removing and recovering the nutrients nitrogen（N）,phosphorus（P）and potassium（K）.As a lab-scale feasibility study,a soil column test was conducted,in which black soil and valuable Kentucky bluegrass were integrated to treat artificial nutrient-enriched wastewater.After a long-term operation,the nitrification function was well established in the top layers,despite the need for an improved denitrification process prior to discharge.P and K were retained by the soil through distinct mechanisms.Since they either partially or totally remained in plant-available forms in the soil,indirect nutrient reuse could be achieved.As for Kentucky bluegrass,it displayed better growth status when receiving wastewater,with direct recovery of 8%,6% and 14% of input N,P and K,respectively.Furthermore,the indispensable role of Kentucky bluegrass for better treatment performance was proved,as it enhanced the cell-specific nitrification potential of the soil nitrifying microorganisms inhabiting the rhizosphere.After further upgrade,the proposed system is expected to become a new solution for strong wastewater pollution.展开更多
The Korea government has put in a lot of effort to construct sanitation facilities for controlling non-point source pollution. The first flush phenomenon is a prime example of such pollution. However, to date, several...The Korea government has put in a lot of effort to construct sanitation facilities for controlling non-point source pollution. The first flush phenomenon is a prime example of such pollution. However, to date, several serious problems have arisen in the operation and treatment effectiveness of these facilities due to unsuitable design flow volumes and pollution loads. It is difficult to assess the optimal flow volume and pollution mass when considering both monetary and temporal limitations. The objective of this article was to characterize the discharge of storm runoff pollution from urban catchments in Korea and to estimate the probability of mass first flush （MFFn） using the storm water management model and probability density functions. As a result of the review of gauged storms for the representative using probability density function with rainfall volumes during the last two years, all the gauged storms were found to be valid representative precipitation. Both the observed MFFn and probability MFFn in BE-1 denoted similarly large magnitudes of first flush with roughly 40% of the total pollution mass contained in the first 20% of the runoff. In the case of BE-2, however, there were significant difference between the observed MFFn and probability MFFn.展开更多
This paper presents a new size effect model for normal strength concrete subjected to uniaxial tension. The model is based on two extremes, sand cement paste in uniaxial tension and a sand-cement-paste/rock interface ...This paper presents a new size effect model for normal strength concrete subjected to uniaxial tension. The model is based on two extremes, sand cement paste in uniaxial tension and a sand-cement-paste/rock interface in uniaxial tension. Uniaxial tension tests with normal strength concrete measuring the tensile strength of normal strength concrete specimens with different geometrical shapes and different ratios of the aggregate size to the characteristic dimension of the concrete specimen show a significant size effect. The theoretical size effect law prediction agrees well with the experimental data.展开更多
基金Under the auspices of the National Social Science Foundation of China(No.16ZDA017)。
文摘As a matter of expediency, most existing corporate-based urban networks can only be quantitatively measured by either counting the number of linkages or calculating the product of estimated service values. However, the impreciseness arising due to the limits of quantitative analysis may prove fatal to studies about non-market economies like China. Employing the capital investment dataset as an example, we build a capital-weighted intervention network as well as an unweighted control network to carry out an examination of the quantitative validity in China’s corporate-based urban network analysis. Both the overall spatial pattern and top city-dyads within the capital-weighted network witness Beijing, as the most dominant city, overshadow the performance of the others, and the unweighted network shows multilateral interactions between China’s top cities including Beijing, Shanghai, Shenzhen, and Guangzhou. To further interpret the noticeable differences, we divide the overall network into two subnetworks, inferred by focusing on state-owned enterprises(SOEs) and private enterprises. The results show that the public and private sectors have separately created vastly different subnetworks in China and that SOEs play a much more significant role in terms of capital. Besides fresh insights into China’s urban network, this study provides a cautionary tale reminding researchers of the essentiality and complexity when making a quantitative distinction between different linkages.
文摘Life cycle assessment (LCA) is one of the most widely used methods of decision support. However, few studies have examined whether stakeholders prefer midpoint or endpoint approaches. In this regard, the present study examines the attitudes toward urban solid waste management, environmental issues, and scenario evaluations by using midpoint and endpoint interpretations of LCA results. This study introduces three types of social groups that typically respond to environmental conflicts: the individualist, hierarchist, and egalitarian groups. Although residents are likely to recognize global impacts as the most important issue, their view is likely to change depending on system and avoided emissions. Consistent with the Seoul Metropolitan Area’s new policy designed to increase the incineration ratio, almost half of all respondents preferred the scenario. Noteworthy is that the respondents’ preference for midpoint and endpoint decision-making tools is not consistent with that in previous studies. Most of the respondents indicated that the midpoint approach would be better in evaluating environmental systems.
基金The National Science Fund for Distinguished Young Scholars (No. 50225824), the National Natural Science Foundation of China(No. 50538090) and the Beijing Academic Innovation Group in Sustainable Water/Waste Recycle Technologies (No. BJE10016200611)
文摘Ozonation of synthetic water containing a type of endocrine disruptor-di-n-butyl phthalate （DBP） was examined. Key impact factors such as pH, temperature, ionic strength, ozone dosage and initial DBP concentration were investigated. In addition, the activities of radicals on uncatalysed and catalysed ozonation were studied. The degradation intermediate products were followed and the kinetic of the ozonation were assessed as well. Results revealed that ozonation of DBP followed two mechanisms. Firstly, the reaction rate of direct ozonation was slower at lower pH, temperature, and ionic strength. Secondly, when these factors were increased for indirect radical reaction, higher percentage of DBP was removed with the increase of the initial ozone dosage and the decrease of the initial DBP concentration. In addition, tea-butanol, humic substances and Fe（Ⅱ） affected DBP ozonation through the radical pathway. It was determined that ozonation was restrained by adding tea-butanol for its radical inhibition effect. Furthermore, humic substances enhanced the reaction to some extent, but a slight negative effect would be encountered if the optimum dosage was exceeded. As a matter of fact, Mn（Ⅱ） affected the ozonation by ＂active sites＂ mechanism. In the experiment, three different kinds of intermediate products were produced during ozonation, but the amount of products for each one of them decreased as pH, temperature, ionic strength and initial ozone dosage increased. A kinetic equation of the reaction between ozone and DBP was obtained.
文摘An estrogen receptor （ER）/androgen receptor （AR） ligand competitive binding assay （ER/AR-binding assay） and chemical analyses were used to evaluate the endocrine disrupting chemicals （EDCs） behavior of two municipal wastewater treatment plants （WWTPs） （K and S）. In the influents, estrone （E 1）, androsterone （A）, androstenedione （AD）, BPA （bisphenol A）, NP （nonylphenol） and daidzein （DZ） were detected in high amounts with subsequent 24 h-average concentrations of 350, 1000, 29, 1300, 3900, and 5700 ng/L in K-WWTP and of 310, 620, 59, 1600, 2600, and 8400 ng/L in S-WWTP. The estrogenic （androgenic） activity as 17β-estradiol （E2） equivalents （EEQ） or testosterone （Te） equivalents （TEQ） was consequently 620 ng E2/L （570 ng Te/L） and 580 ng E2/L （800 ng Te/L） for the two WWTPs. The removal efficiencies of the above mentioned sole target chemicals were 51%-100% for K-WWTP and 55.6%-100% for S-WWTP. The removal efficiencies of EEQ were about 73% for both WWTPs, while the removal efficiencies of TEQ were 62.1% for K-WWTP and 98.4% for S-WWTP. In addition, chemical-derived EEQ were about 1.2%-52.4% of those by ER-binding assay for K-WWTP and the corresponding ratios were 1.3%-83.3% for S-WWTP, while chemical derived TEQ were less than 3% of values measured by the AR-binding assay for both WWTPs.
文摘The development and rapid usage of numerical codes for fluid-structure interaction(FSI) problems are of great relevance to researchers in many engineering fields such as civil engineering and ocean engineering. This multidisciplinary field known as FSI has been expanded to engineering fields such as offshore structures, tall slender structures and other flexible structures applications. The motivation of this paper is to investigate the numerical model of two-way coupling FSI partitioned flexible plate structure under fluid flow. The adopted partitioned method and approach utilized the advantage of the existing numerical algorithms in solving the two-way coupling fluid and structural interactions. The flexible plate was subjected to a fluid flow which causes large deformation on the fluid domain from the oscillation of the flexible plate. Both fluid and flexible plate are subjected to the interaction of load transfer within two physics by using the strong and weak coupling methods of MFS and Load Transfer Physics Environment, respectively. The oscillation and deformation results have been validated which demonstrate the reliability of both strong and weak method in resolving the two-way coupling problem in contribution of knowledge to the feasibility field study of ocean engineering and civil engineering.
文摘The effectiveness of chlorine and ultraviolet light at inactivating indigenous microbes in primary treated wastewater was examined in this study. The inactivation rates for somatic colipahge and F-specific bacteriophage were less than 2.5 log and 1 log, respectively, at either free chlorine doses of 6, 15 mg/L and 30 mg/L after 30 minutes contact time. However, E. coli and total coliforms were susceptible to chlorination and inactivated more than 4 log within first 15 minutes of contact time at any chlorine dosage tested. In contrast, the inactivation of bacteriophage was increased when increasing UV fluence. At the same disinfection effectiveness against E. coli, UV disinfection was more effective than chlorination against F-specific bacteriophages.
文摘Minimizing water loss in water supply networks is one of the objectives for protecting water resources. Currently, the large amount of water loss is mainly due to leakage of the pipeline network. The leaking of pipe can be caused by incorrect construction, impacted by external forces, or corroded pipe material and aging. Therefore, to control and predict the cracking area on pipe, it is necessary to collect data about pipe conditions, approve the solution of technology improvement and define the ability of pipe capacity from setting up to the first preparing time. This paper will demonstrate how to evaluate corrosion pipe under the age of pipe and the impact level of internal pressure pipe at different times, and will put forward solution of effective leaking management on water supply network.
文摘In Tokyo, as residential areas exist in the urban areas and are composed of areas owned by individual land owners, basically spatial changes are brought by redevelopments of each sites conducted by individual circumstances and motivations. Continuous redevelopments and spatial changes can be found dispersedly in areas. Once the spatial change in a certain site occurred in an area as a building, it will be contained in the built environment of the residential area which is defined by residents, planners and designers who will take part in the following spatial changes. In Tokyo, public transportation facilities are well developed, and residents＇ daily life involves activities such as a slow walking and bicycle, etc. around the place of residence near the public transportation hubs, each living territories are formed in this kind of manner. Considering the maintenance of spatial value in residential areas while understanding transformation of visual local environment in residential areas which focuses on appearance of each spatial change in an area of street will be of significant importance. In this paper, the authors try to describe interactions of spatial changes in existing urban residential areas focusing on utility of players who might take part in the following spatial changes and the method of discrete choice model.
文摘We analyzed the determinants of building bridges after comparing bridge islands and non-bridge islands.In addition,we examined the population change before and after the bridge building and the factors influencing the change.As a result,a remote island with high cost-effectiveness was selected and bridged.The early bridge was built in remote islands with fragile social infrastructure,and the outflow of population was suppressed owing to the improvement in standard of living by securing the medical care and education available in the bridge destination.However,around the year 2000,there are few remote islands where the changes in populations are influenced after a bridge was built.
文摘Facing challenges of population decline and fiscal austerity,Japan has implemented a series of initiatives to promote public-private partnerships(PPP)to ensure the sustainability of urban parks and revitalize urban spaces.These initiatives,while alleviating the government’s financial burdens on parks,have also raised concerns about the potential erosion of publicness and public interests resulted from the commercialization of public assets.This paper reviews the evolution of Japan’s urban park management system after World War II—including three phases of being purely public goods,initiating marketization,and diversifying management entities.The functions of parks have continuously enriched,and the construction,management,and operational modes have shifted from government-led towards multi-stakeholder participation,along with expanded funding sources.By examining the PPP types,driving forces,implementation mechanisms and challenges in urban park management,this paper points out that,in different eras and social contexts,the Japanese government has kept adjusting its role to maximize public interests.This has proactively updated the implications of publicness in infrastructure like urban parks,from a post-war opposite of publicness versus privateness on ownership,to the participation of private capital for a higher efficiency,and finally to a community for a stronger regional competitiveness.The reforms of urban park management system in Japan offer significant lessons and insights for urban infrastructure management in other countries and regions.
文摘Based on an in-depth survey of different typical areas that are selected in different regions and at different levels, this paper identifies the general characteristics of China's urbanization, the impacts that economic development driven by both exogenous and endogenous engines has on the spatial pattern of urbanization, and the two urbanization paths:gradient development and hierarchal advancement. By analyzing such factors as population growth, population mobility, and economic and industrial development, it sums up five spatial patterns for future urbanization development trends. Through the analyses on the three aspects:whereabouts of the present 260 million migrant workers and their families, whereabouts of the new-born population and new working-age rural population, and the migrant scale of the existing agricultural labors moving to non-agricultural industries, this paper predicts that China's urbanization rate will slow down in the next five to ten years, and will reach about 65 percent in around 2030. On the basis of the analyses, it puts forward that "Five-Six-Eleven" regional pattern of urbanization should be established to guide the overall strategy for spatial pattern optimization. To optimize the spatial pattern of urbanization, it proposes specific strategies including coordinated development of large, medium-sized, and small cities, and small towns, as well as urbanization development strategies of differentiation according to different classes and regions.
基金supported by the 2006 Core Construction Technology Development Project (06KSHS-B01)through ECORIVER21 Research Center in KICTTEP of MOCT
文摘This article aims to describe the influence of diffuse pollution on the temporal and spatial characteristics of natural organic matter （NOM） in a stratified dam reservoir, the Daecheong Dam, on the basis of intensive observation results and the dynamic water quality simulation using CE-QUAL-W2. Turbidity is regarded as a comprehensive representation of allochothonous organic matter from diffuse sources in storm season because the turbidity concentration showed reasonable significance in a statistical correlation with the UV absorbance at 254 nm and total phosphorus. CE-QUAL-W2 simulation results showed good consistency with the observed data in terms of dissolved organic matter （DOM） including refractory dissolved organic carbon （RDOC） and labile DOC and also well explained the internal movement of constituents and stratification phenomenon in the reservoir. Instead turbidity and NOM were related well in the upper region of the reservoir according to flow distance, gradually as changing to dissolved form of organic matter, RDOM affected organic matter concentration of reservoir water quality compared to turbidity. To control the increase of soluble organic matters in the dam reservoir, appropriate dam water discharge gate operation provided effective measurement. Because of the gate operation let avoid the accumulation of organic matter within a dam reservoir by shorten of turbid regime retention time.
基金supported by the National Water Science and Technology Project (No.2017ZX07203-003)the National Basic Research Program of China (No.2017YFA0605201)the support from the National Natural Science Foundation of China (No.412111020)
文摘Microcystis panniformis is a bloom forming species with flat panniform-like colonies. This species was recently found in Lake Taihu, China. To specifically characterize M. panniformis based on isolated strains, morphological examination on colonial transition and genetic examination are needed. Three M. panniformis strains isolated from a water bloom sample in Lake Taihu were characterized by molecular analysis and toxin quantification. Phylogenetic analysis based on both 16S rRNA gene and internal transcribed spacer(ITS) between 16S and 23S rRNA genes were performed and compared to facilitate easy identification of the species.Relatively high similarities(98%–99%) were shown in 16S rDNA sequences between the strains of M. panniformis and those of other Microcystis species, whereas the similarities for ITS sequences were 88%–95%. In the phylogenetic tree based on the 16S rDNA sequences, the M. panniformis and M. aeruginosa strains were intermixed together with no clear division,whereas all of the M. panniformis strains were clustered together in a single clade based on the ITS sequences based phylogenyetic tree. The mcyE gene was detected in all three strains, and microcystin was determined by high-performance liquid chromatography. The molecular detection and toxin production of M. panniformis strains are of great significance for the environmental risk assessment of Microcystis blooms.
基金supported by the Environment Research and Technology Development Fund (S-8) of the Ministry of the Environment, Japan, Grant-inAid for Scientific Research (#22404012) by JSPSthe CREST Project Fund by JST
文摘Anion exchange resins （AERs） with different properties were evaluated for their ability to remove dissolved organic matter （DOM） and bromide, and to reduce disinfection by-product （DBP） formation potentials of water collected from a eutrophic surface water source in Japan. DOM and bromide were simultaneously removed by all selected AERs in batch adsorption experiments. A polyacrylic magnetic ion exchange resin （MIEX） showed faster dissolved organic carbon （DOC） removal than other AERs because it had the smallest resin bead size. Aromatic DOM fractions with molecular weight larger than 1600 Da and fluorescent organic fractions of fulvic acid- and humic acid-like compounds were efficiently removed by all AERs. Polystyrene AERs were more effective in bromide removal than polyacrylic AERs. This result implied that the properties of AERs, i.e. material and resin size, influenced not only DOM removal but also bromide removal efficiency, MIEX showed significant chlorinated DBP removal because it had the highest DOC removal within 30 rain, whereas polystyrene AERs efficiently removed brominated DBPs, especially brominated trihalomethane species. The results suggested that, depending on source water DOM and bromide concentration, selecting a suitable AER is a key factor in effective control of chlorinated and brominated DBPs in drinking water.
基金supported by JST-CREST, JSPS-KAKENHI (No. 26241025)MEXT-GRENE
文摘Diarrheal diseases can be transmitted via both primary infection due to exposures to contaminated materials from the environment and secondary infection due to person- to-person contacts. Usually, the importance of secondary infection is empirically assessed by fitting mathematical models to the epidemic curves. However, these empirical models may not be applicable to other epidemic cases because they are developed only for the target epidemics and they don＇t consider the detail routes of infection. In our previous study, we developed a theoretical model taking into account the various routes of infection that commonly occur in households （e.g., shaking hands, food handling, and changing diapers）. This model was made flexible and applicable to any epidemics by means of adjusting model parameters. In this study, we proposed a new index ＂Vulnerability indicator to secondary infection （VISI）＂, which expressed a ratio of secondary infection to primary infection risks and calculated this index in a simulated norouirus （NOV） epidemic that involved I0,000 households. The results demonstrated that households composed of more than three members including infant（s） had much higher levels of VlSl （5-45） than two-member-households with VlSI （0.1-4）. These results concluded that the infants were likely to be a hub of secondary infections in highly dense families and therefore careful handling of diapers was deemed indispensible in such families to effectively control the secondary infections.
基金greatly supported by the Japan Society for the Promotion of Science(JSPS)KAKENHI Grant Number 26303012
文摘To develop a sound post-treatment process for anaerobically-digested strong wastewater,a novel natural treatment system comprising two units is put forward.The first unit,a trickling filter,provides for further reduction of biochemical oxygen demand and adjustable nitrification.The subsequent soil–plant unit aims at removing and recovering the nutrients nitrogen（N）,phosphorus（P）and potassium（K）.As a lab-scale feasibility study,a soil column test was conducted,in which black soil and valuable Kentucky bluegrass were integrated to treat artificial nutrient-enriched wastewater.After a long-term operation,the nitrification function was well established in the top layers,despite the need for an improved denitrification process prior to discharge.P and K were retained by the soil through distinct mechanisms.Since they either partially or totally remained in plant-available forms in the soil,indirect nutrient reuse could be achieved.As for Kentucky bluegrass,it displayed better growth status when receiving wastewater,with direct recovery of 8%,6% and 14% of input N,P and K,respectively.Furthermore,the indispensable role of Kentucky bluegrass for better treatment performance was proved,as it enhanced the cell-specific nitrification potential of the soil nitrifying microorganisms inhabiting the rhizosphere.After further upgrade,the proposed system is expected to become a new solution for strong wastewater pollution.
文摘The Korea government has put in a lot of effort to construct sanitation facilities for controlling non-point source pollution. The first flush phenomenon is a prime example of such pollution. However, to date, several serious problems have arisen in the operation and treatment effectiveness of these facilities due to unsuitable design flow volumes and pollution loads. It is difficult to assess the optimal flow volume and pollution mass when considering both monetary and temporal limitations. The objective of this article was to characterize the discharge of storm runoff pollution from urban catchments in Korea and to estimate the probability of mass first flush （MFFn） using the storm water management model and probability density functions. As a result of the review of gauged storms for the representative using probability density function with rainfall volumes during the last two years, all the gauged storms were found to be valid representative precipitation. Both the observed MFFn and probability MFFn in BE-1 denoted similarly large magnitudes of first flush with roughly 40% of the total pollution mass contained in the first 20% of the runoff. In the case of BE-2, however, there were significant difference between the observed MFFn and probability MFFn.
文摘This paper presents a new size effect model for normal strength concrete subjected to uniaxial tension. The model is based on two extremes, sand cement paste in uniaxial tension and a sand-cement-paste/rock interface in uniaxial tension. Uniaxial tension tests with normal strength concrete measuring the tensile strength of normal strength concrete specimens with different geometrical shapes and different ratios of the aggregate size to the characteristic dimension of the concrete specimen show a significant size effect. The theoretical size effect law prediction agrees well with the experimental data.
