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Phosphorus limitation on bacterial regrowth in drinking water

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Journal of Environmental Sciences 2003年第6期15卷 773-778页

作者： sangjun-qiang ZHANGXi-hui YUGuo-zhong WANGZhan-sheng ResearchCenterforEnvironmentalEngineeringandManagement ShenzhenGraduateSchoolTsinghuaUniversityShenzhen518057China. DepartmentofEnvironmentalScienceandEngineering TsinghuaUniversityBeijing100084China

Assimilable organic carbon(AOC) test and bacterial regrowth potential(BRP) analysis were used to investigate the effect of phosphorus on bacterial regrowth in the drinking water that was made from some raw water taken from a reservoir located in northern China. It was shown that AOC of the drinking water samples increased by 43.9%—59.6% and BRP increased by 100%—235% when 50 μg/L PO 3- 4-P(as NaH 2PO 4) was added alone to the drinking water samples. This result was clear evidence of phosphorus limitation on bacteria regrowth in the drinking water. This investigation indicated the importance of phosphorus in ensuring biological stability of drinking water and offered a novel possible option to restrict microbial regrowth in drinking water distribution system by applying appropriate technologies to remove phosphorus efficiently from drinking water in China.

关键词： drinking water bacterial regrowth phosphorus AOC biological stability

Modification on the conventional procedure to measure AOC in drinking water

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Journal of Environmental Sciences 2004年第6期16卷 996-1000页

作者： LIFu-zhi sangjun-qiang ZHANGXi-hui WANGZhan-sheng ResearchCenterforEnvironmentalEngineering＆Management ShenzhenGraduateSchoolTsinghuaUniversityShenzhen518055China DepartmentofEnvironmentalScienceandEngineering TsinghuaUniversityBeijing100084China

Additional phosphorus will be introduced to water sample if the conventional procedure is used to measure assimilable organic carbon(AOC) in drinking water. It has been shown that there are the cases that phosphorus is the limiting nutrient for microbial growth in drinking water. The measured value of AOC would not be able to indicate appropriately the regrowth potential of bacteria in this case. The conventional procedure used to measure AOC was modified to avoid the introduction of additional phosphorus to water sample in this study. It was shown that it was feasible to measure AOC in water using the modified procedure. Furthermore, the measured value of AOC determined by the modified procedure could indicate appropriately the regrowth potential of bacteria in drinking water despite either organics or phosphorus was the limiting nutrient for bacterial regrowth.

关键词： drinking water assimilable organic carbon bacterial regrowth phosphorus organics

Real-time porosity reduction during metal directed energy deposition using a pulse laser

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Journal of Materials Science & Technology 2022年第21期116卷 214-223页

作者： Hoon Sohn Peipei Liu Hansol Yoon Kiyoon Yi Liu Yang sangjun Kim Department of Civil and Environmental Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Center for 3D Printing Nondestructive Testing Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Global R&D Center SQ EngineeringSeoul 05818Republic of Korea Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina

Porosity is a challenging issue in additive manufacturing and is detrimental to the quality of the additively manufactured *** this study,a real-time porosity reduction technique was developed by incorporating a pulse laser into a laser metal powder directed energy deposition(DED)*** incorporated pulse laser can accelerate fluid flow within the melt pool and facilitate the escape of pores before complete *** achieves this real-time porosity reduction by inducing accelerated and turbulent Marangoni flow,ultrasonic waves,and shock waves into the melt *** uniqueness and advantages of the proposed technique include the following:(1)For a laser metal powder DED process,this study proposed a noncontact,nondestructive,and real-time porosity reduction technique at the melt pool level.(2)It was experimentally and numerically validated that the developed technique did not alter the geometry and the grain structure of the manufactured Ti-6Al-4V samples.(3)Because the porosity reduction is accomplished at the melt pool level,its application is not limited by the size,shape,or complexity of the printing target.(4)The developed technique can be readily incorporated into the existing DED systems without any modification of the original tool-path *** experimental results showed that the pore volume fraction decreased from 0.132%to 0.005%,no pores larger than 6×10^(4)μm^(3) were observed,and a 91%reduction in the total pore number was achieved when the pulse laser energy reached 11.5 mJ.

关键词： Real-time porosity reduction Pulse laser Melt pool Directed energy deposition Ti-6Al-4V

Modeling Inclement Weather impacts on Traffic Stream Behavior

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International Journal of Transportation Science and Technology 2012年第1期1卷 25-47页

作者： Hesham Rakha Mazen Arafeh sangjun Park Charles E.Via Jr.Department of Civil and Environmental Engineering Virginia Tech Transportation Institute3500 Transportation Research PlazaBlacksburgVA 24061USA Virginia Tech Transportation Institute 3500 Transportation Research PlazaBlacksburgVA 24061USA

The research identifies the steady-state car-following model parameters within state-of-thepractice traffic simulation software that require calibration to reflect inclement weather and roadway *** research then develops procedures for calibrating non-steady state carfollowing models to capture inclement weather impacts and applies the procedures to the INTEGRATION software on a sample *** results demonstrate that the introduction of rain precipitation results in a 5%reduction in light-duty vehicle speeds and a 3%reduction in heavy-duty vehicle *** increase in the rain intensity further reduces light-duty vehicle and heavy-duty truck speeds resulting in a maximum reduction of 9.5%and 5.5%at the maximum rain intensity of 1.5 cm/h,*** results also demonstrate that the impact of rain on traffic stream speed increases with the level of congestion and is more significant than speed differences attributed to various traffic operational improvements and thus should be accounted for in the analysis of *** the case of snow precipitation,the speed reductions are much more significant(in the range of 55%).Furthermore,the speed reductions are minimally impacted by the snow precipitation *** study further demonstrates that precipitation intensity has no impact on the relative merit of various scenarios(*** ranking of the scenario results are consistent across the various rain intensity levels).This finding is important given that it demonstrates that a recommendation on the optimal scenario is not impacted by the weather conditions that are considered in the analysis.

关键词： weather intensity Stream

Formation of sub-100-nm suspended nanowires with various materials using thermally adjusted electrospun nanofibers as templates

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Microsystems & Nanoengineering 2023年第1期9卷 263-270页

作者： Yongkeun Oh Dae-Sung Kwon Eunhwan Jo Yunsung Kang sangjun Sim Jongbaeg Kim School of Mechanical Engineering Yonsei UniversitySeoul03722Republic of Korea

The air suspension and location specification properties of nanowires are crucial factors for optimizing nanowires in electronic devices and suppressing undesirable interactions with *** various strategies have been proposed to fabricate suspended nanowires,placing a nanowire in desired microstructures without material constraints or high-temperature processes remains a *** this study,suspended nanowires were formed using a thermally aggregated electrospun polymer as a *** elaborately designed microstructure enables an electrospun fiber template to be formed at the desired location during thermal ***,the desired thickness of the nanowires is easily controlled with the electrospun fiber templates,resulting in the parallel formation of suspended nanowires that are less than 100 nm ***,this approach facilitates the formation of suspended nanowires with various *** is accomplished by evaporating various materials onto the electrospun fiber template and by removing the ***,copper,tungsten oxide(WO3),and tin oxide nanowires are formed as examples to demonstrate the advantage of this approach in terms of nanowire material ***(H2)and nitrogen dioxide(NO2)gas sensors comprising palladium and tungsten oxide,respectively,are demonstrated as exemplary devices of the proposed method.

关键词： nanowires template fibers

Virginia Tech Comprehensive Power-based Fuel Consumption Model(VT-CPFM):Model Validation and Calibration Considerations

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International Journal of Transportation Science and Technology 2013年第4期2卷 317-336页

作者： sangjun Park Hesham A.Rakha Kyoungho Ahn Kevin Moran aDepartment of Civil Engineering Chosun University309 Pilmun-daero Dong-gu Gwangju 501-759South Korea Charles E.Via Jr.Department of Civil and Environmental Engineering3500 Transportation Research PlazaBlacksburgVA 24061 Center for Sustainable Mobility Virginia Tech Transportation Institute3500 Transportation Research PlazaBlacksburgVA 24061 Nokia Here 425 West Randolph StreetChicagoIL 60606

A power-based vehicle fuel consumption model,entitled the Virginia Tech Comprehensive Power-based Fuel Consumption Model(VT-CPFM)that was developed in an earlier publication is validated against in-field fuel consumption *** study demonstrates that the VT-CPFMs calibrated using the EPA city and highway fuel economy ratings generally provide reliable fuel consumption estimates with a coefficient of determination in the range of *** importantly,both estimates and measurements produce very similar behavioral changes depending on engine load *** VT-CPFMs are demonstrated to be easily calibrated using publically available data without the need to gather in-field instantaneous data.

关键词： Consumption Power estimates

Fuel Economy impacts of Manual,Conventional Cruise Control,and Predictive Eco-Cruise Control Driving

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International Journal of Transportation Science and Technology 2013年第3期2卷 227-242页

作者： sangjun Park Hesham A.Rakha Kyoungho Ahn Kevin Moran Department of Civil Engineering Chosun University 309 Pilmun-daero Dong-gu Gwangju 501-759South Korea Center for Sustainable Mobility Virginia Tech Transportation Institute 3500 Transportation Research PlazaBlacksburgVA 24061 Nokia Location and Commerce 425 West Randolph Street ChicagoIL 60606

The paper presents the results of a field experiment that was designed to compare manual driving,conventional cruise control(CCC)driving,and Eco-cruise control(ECC)driving with regard to fuel *** field experiment was conducted on five test vehicles along a section of Interstate 81 that was comprised of±4%uphill and downhill grade *** an Onboard Diagnostic II reader,instantaneous fuel consumption rates and other driving parameters were collected with and without the CCC system *** collected data were compared with regard to fuel economy,throttle control,and travel *** results demonstrate that CCC enhances vehicle fuel economy by 3.3 percent on average relative to manual driving,however this difference was not found to be statistically significant at a 5 percent significance *** results demonstrate that CCC driving is more efficient on downhill versus uphill *** addition,the study demonstrates that an ECC system can produce fuel savings ranging between 8 and 16 percent with increases in travel times ranging between 3 and 6 *** benefits appear to be largest for heavier vehicles(SUVs).

关键词： Cruise driving travel

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无序合金的热力学过程和薄膜生长机理

无序合金的热力学过程和薄膜生长机理

作者： sangjun Kang 浙江大学

学位级别：硕士

Metallic glasses are structurally disordered alloys whose compositions are designed to impede crystallization upon cooling from the liquid *** are firstly developed in the early *** to their superior properties,e.g.,very high corrosion and wear resistance,great yield strength and elastic limit,studies on BMGs are of *** or thermal treatment of metallic glasses at near glass transition temperature triggers relaxation and often hampers their performances in *** treatment of MGs by thermal cycling is recently intensively ***,the mechanism responsible for the structural rejuvenation still remains *** this thesis,we conduct systematic studies of on the rejuvenation effect of a Zr-based metallic glass annealed at near glass transition temperature for various durations,subjected to thermo-cycling treatment and a growth behavior of AuCuSi alloy film by in-situ grazing incidence small angle X-ray *** is found that well relaxed samples after long-term annealing are almost unaffected by thermal cycling *** contrast,while short-term annealed samples exhibit large rejuvenation effect by thermo-cycling *** synchrotron X-ray diffraction,we find that thermal cycling results in a disordering at the short-range scale,where the rejuvenation effect is large in a heterogeneous *** interestingly,the thermo-cycling treatment on intermediate structure with 20 h-annealed sample relatively exhibits a high degree rejuvenation effect,as compared to shorter and longer annealed *** finding indicates that the activation barrier for rejuvenation strongly depends on the original structural states,e.g.,free volume,inherent stress and structural ***-alloy coatings and films and studies have become growing of importance in recent days,especially for corrosion and wear resistance coatings,soft magnetic thin films and micro-electromechanical systems(MEMSs).Yet,high q

关键词： Metallic glasses Thermo-cycling Growth kinetic GISAXS Synchrotron radiation

Engineering Geometric Electrodes for Electric Field-Enhanced High-Performance Flexible In-Plane Micro-Supercapacitors

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Energy & Environmental Materials 2023年第4期6卷 114-120页

作者： Jihong Kim Sung Min Wi Jong-Guk Ahn sangjun Son Hee Young Lim Yeonsu Park Hye Ji Eun Jong Bae Park Hyunseob Lim Sangyeon Pak A-Rang Jang Young-Woo Lee Department of Energy Engineering Soonchunhyang UniversityAsan 31538Korea Department of Chemistry Gwangju Institute of Science and TechnologyGwangju 61005Korea Jeonju Centre Korea Basic Science InstituteJeonju 54907Korea Prof.S.Pak School of Electronic and Electrical Engineering Hongik UniversitySeoul 04066Korea Division of Electrical Electronic and Control EngineeringKongju National UniversityCheonan 31080Korea

In plane micro-supercapacitors that are miniaturized energy storage components have attracted significant attention due to their high power densities for various ubiquitous and sustainable device systems as well as their facile integration on various flexible/wearable *** implement the micro-supercapacitors in various practical applications that can accompany solid state or gel electrolyte and flexible substrates,ions must be readily transported to electrodes for achieving high power ***,we show large enhancement in electrochemical properties of flexible,inplane micro-supercapacitor using sharp-edged interdigitated electrode design,which was simply fabricated through direct laser scribing *** sharp-edged electrodes allowed strong electric field to be induced at the corners of the electrode fingers which led to the greater accumulation of ions near the surface of electrode,significantly enhancing the energy storage performance of *** electric field-enhanced in-plane micro-supercapacitor showed the volumetric energy density of 1.52 Wh L^(−1)and the excellent cyclability with capacitive retention of 95.4%after 20000 *** further showed various practicability of our sharp-edged design in micro-supercapacitors by showing circuit applicability,mechanical stability,and air *** results present an important pathway for designing electrodes in various energy storage devices.

关键词： electric field enhancement flexible energy storage device microsupercapacitors sharp electrodes