Assessing water quality changes and transition effects in distribution systems by online particle sampling system (OPSS)

The drinking water safety has been paid close attention, and the water purification development and distribution cleaning have been widely studied. To meet stricter water quality regulations and fight new emerging pollutants, upgrading treatment processes to improve treated water quality has become common practices worldwide. However, the quality improved drinking water still needs to be delivered by the old distribution system with harboured material which may cause serious water quality deterioration during the shifting of supply water quality. Until now, the accompanying transition effects within distribution networks caused by changes of water quality or hydraulic condition have been poorly documented. These irregular operations will impact water qualitynegatively through the associated physiochemical and microbiological destabilization of accumulated materials such as loose deposits resuspension and biofilm detachment.The destabilized materials would be released as suspended solids into bulk water and travel throughout distribution networks. Therefore, the investigation on changes of suspended solids characteristics is the key to understand transition effects. To study the transition effects through suspended solids, there are challenges: 1) suspended solids are diluted in the big volume of water, resulting in low concentration if take water samples; 2) the detection limit of regular parameters makes the changes hard to be noticed; 3) therelease of suspended particles is non-periodicity, which leads to the difficulty of catching the moment.In my studies, the online particle sampling system (OPSS) was applied in three distribution systems to collect and monitor suspended solids, which successfully overcame all of the three challenges mentioned above. The main objective of this report is to study water quality changes under regular operations, and transition effects under irregular operations such as the upgraded treatment and pipe cleaning by using OPSS. At the end of the report, the problems were diagnosed and the management strategies were proposed for different systems

我國五年制專科教育問題之研究

[[abstract]]本研究採用描述研究法（Descriptive Research），除從事理論探討外，主要採用問 卷調查方式，以收集所需資料，所使用之調查工具，係自編之「五年制專科教育調查 問卷」，本調查共寄發問卷二六○一份，計收回有效問券二○○八份，扣除退件及廢 卷一二二份，回收率為八一•○％。整理回收問卷，並經統計分析後，獲致下列結論 ： 壹、五專教育之現況 一、學生入學背景 （一）目前學生報考五專的原因中，仍以不必再受升學競爭的壓力為最優先考慮的因 素；可見五專教育未能以高教育品質及易於就業與進修等因素來吸引學生。 （二）五專學生於入學前還未能確定那些類科較符合自己的興趣，且對各類科的教育 目標及教學內涵以不甚了解者居多。 二、課程問題 （一）五學年內之各類課程（實習課程、專業課程與一般課程）內容的安排，認為大 部份不重複者約佔五分之四，顯見五專在各類課程內容的安排上頗能避免重複，達到 課程設計五年一貫的精神。 （二）關於五專學校所開各類課程內容與就業需要的配合情形，實習課程、專業課程 與一般課程內容僅小部份能配合就業需要，其中尤以一般課程最為重要。可見各類課 程內容應重新檢討與安排，使更能配合就業的需要。 （三）五專之實習課程與專業課程的上課時數，有不足的情形，應針對各類科的需要 酌予增多。一般課程的上課時數卻有過多的現象，亦應專就各類科的特性加以檢討。 （四）目前五專後二年的專業課程以採用大學教科書為主，公、私立五專學生認為採 用大學及專科用教科書與課程能配合者，約佔五分之四，約五分之三的學生認為採用 高職用教科書與課程不能配合。 三、設備問題 （一）五專基礎教育及高年級用之實習設備分未能滿足教學需要而公立五專的要求較 高故認為不夠者的比率較私立五專為高。 （二）五專基礎教育所用之專業實習設備水準的現況，以同時使用高職及五專高年級 水準的實習設備者居多，部分五專則與高職設備水準相同。 （三）各類人員認為基礎教育同時使用高職及五專高年級的專業實習設備，較能提高 教學效果，但是基礎教育使用高年級的專業實習設備較不符合經濟效益。 四、師資問題 （一）五專高年級師資的現況，根據調查結果，以認為部份師資有才學不足或大才小 用的情形者居多。其中尤以師資有才學不足的情形為甚；可見部份五專高年級師資的 素質有待提昇。 （二）各類人員認為基礎教育若由大專師資擔任，較能提高教學效果，然而，基礎教 育課程部份與高職相仿，若由大專師資擔任，易形成教育投資上的浪費。 五 、五專收費標準與最低學分數問題 （一）目前五專前三學年之學雜費收費標準應酌予降低，但仍應比高職收費標準高為 宜。 （二）目前五專最低畢業學分數為二二○學分的規定，應依據各類科的特性重新檢討 ，適度增加或減少以滿足各類科的需要。 六、轉科與轉學問題 （一）根據調查結果，五專學生反應曾想轉科或轉學者的次數，高於未曾想轉科或轉 學者；在曾想轉科或轉學的填答次數中，以未能順利轉科或轉學者居多，約佔五分之 四。可見目前五專學生想轉科或轉學的現象甚為嚴重，且實際轉科或轉學的管道未能 暢通，無法滿足學生的需求，應謀求疏解及改善的辦法。 （二）根據調查結果，五專學生想在校轉科的原因中，以想轉到較符合自己興趣的類 科者為最主要因素；可見目前五專在校學生中，部份因所習的類科與興趣不符合，以 致學習情緒不穩定而想轉科，此種情形應謀求改善，以提高學生的學習效果。 （三）根據調查結果，五專學生轉學的原因中，以反應想轉學到其他教學效果應好的 五專者為最主要因素，尤以私立五專為甚，約佔二分之一。可見部份私立五專辦學成 效不佳，造成學生對學校不滿意而想轉學，對於此類的私立五專應輔導其改善教學， 以提高教育品質。 七、五專教育成效評估 （部份五專畢業生就業適應有困難，尤以私立五專畢業生為甚；可見目前專科教育人 力已呈過剩現象，且面臨失業及低度就業問題，部份私校因教學成效不佳，致畢業生 就業適應有困難。 （二）約五分之三的五專畢業生深信本身有繼續深造的能力，但是，五專與二、三專 的升學機會一樣多。 （三）五專學生在學中之學習意願有逐漸降低者，約佔五分之二；可見部份五專學生 在學期間的學習意願有逐漸降低的趨勢。無論公、私立五專，學校辦學成效欠佳及學 生在學中所習類科不合興趣是造成學生學習意願逐漸降低的重要原因。 （四）就五專畢業生若再做選擇時，以反應「升學五專」者，約佔五分之二，希望能 另外做選擇者，佔二分之一；可見部份學生對五專的教育成效，評價不佳，故應提高 五專教育品質，改善五專教育學制，以吸引學生接受五專教育。 貳、五專教育之政策方向 一、日本之五專是有計劃的國家投資，不准私人濫設，故以國立學校為最多。而我國 之五專則絕大部份為私立學校，私校因經費籌措困難 政府輔助之經費有限，致教育 素質不易全面提高。 二、英國、西德及美國專科學生入學前多需有相當年限之實際工作經驗，如此可事先 讓學生對其本身之性向、能力與興趣有試探的機會，減少因所習類科不符興趣而想轉 科的現象。 三、在專科教育學制方面，各國均以一至三年制為主流，大部份以事實需要來分類分 科，沒有統一制度，頗富彈性。 四、學生修畢五專前三年課程後，應有再選擇就業或升學的機會，以滿足學生的需求 ，所以，五專教育應建立彈性學制，使學生有再選擇就業或升學的機會。

Optimal Estimate of Global Biome: Specific Parameter Settings to Reconstruct NDVI Time Series with the Harmonic ANalysis of Time Series (HANTS) Method

Terrestrial remote sensing data products retrieved from radiometric measurements in the optical and thermal infrared spectrum such as vegetation spectral indices can be heavily contaminated by atmospheric conditions, including cloud and aerosol layers. This contamination results in gaps or noisy observations. The harmonic analysis of time series (HANTS) has been widely used for time series reconstruction of remote sensing imagery in recent decades. To use HANTS model, a series of parameters, such as number of frequencies (NF), fitting error tolerance (FET), degree of over-determinedness (DoD), and regularization factor (Delta), need to be defined by users. These parameters provide flexibilities, but also make it difficult for non-expert users to determine appropriate settings for specific applications. This study systematically evaluated the reconstruction performance of the model under different parameter setting scenarios by simulating pixel-wise reference and noisy NDVI time series. The results of these numerical experiments were further used to identify optimal settings and improve global NDVI reconstruction performance. The results suggested optimal settings for different areas (local optimization). If a user opts to use unique settings for global reconstruction, the setting NF = 4, FET = 0.05, DoD = 5, and Delta = 0.5 can produce the best performance across all setting scenarios (global optimization). In addition, several internal improvements, such as dynamic weighting scheme, polynomial and inter-annual harmonic components, and ancillary attributes of input data can be used to further improve the performance of reconstruction. With these results, future non-expert users can easily determine appropriate settings of HANTS for specific applications in different regions.Optical and Laser Remote Sensin

Impact damage of composite laminates with high-speed waterjet

Rain erosion may cause substantial damage to aircrafts during supersonic flight. Such event is investigated here via high-speed waterjet impact on composite laminates. An experimental setup is developed to produce waterjets with the speed up to 700m/s and a finite element model of the waterjet-composite impact event is established. The consistency of experiment and simulation results validates the adopted numerical methods. The distribution of the water-hammer pressure is non-uniform and the maximum pressure occurs near the contact periphery when the water is about to eject laterally. After a high-speed (300∼560m/s) waterjet impacts a composite laminate, the impacted surface depression is observed, and the typical surface damage presents a central region with no visible surface damage surrounded by a faded “failure ring” with resin removal, matrix cracking and minor fiber fracture. Delamination occurs at the interfaces of adjacent layers with unequal dimensions and longitudinal matrix cracking appears on the back surface. Both the velocity and the diameter of waterjets are crucial factors on CFRP damage extents. Water-hammer pressure, the stagnation pressure and propagation of stress waves are failure mechanisms for most matrix damage in CFRP impacted by waterjets.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite

Multi-phase modelling of multi-species transport in concrete: In case of electrochemical protection for both ASR and chloride attack

Existing reinforced concrete structures experience severe durability degradation when subjected to alkali–silica reaction (ASR) and chloride attack. A special electrochemical rehabilitation treatment, containing lithium compound anolyte, has been developed to drive lithium ions into concrete as well as remove chlorides simultaneously, for mitigating both the ASR-induced cracks and the chloride-induced corrosion. Good performance of introduced lithiums in controlling ASR-induced expansion has already been proved. Unfortunately, the migration mechanism of lithium in concrete under an external electric field is seldom investigated in existing literature. In this study, with help of the “double-multi” model, the efficiency of impregnation of lithium ions and simultaneously the removal of chloride ions through a specific electrochemical treatment are numerically evaluated, which results into the distribution profiles of all typical ionic species. The heterogeneous concrete model examines the aggregate effect, especially on the interaction with lithiums which are supposed to mitigate ASR. The ionic interaction between different species and the electrochemical reaction at electrodes are also considered. Through a relative thorough modelling of multiphase and multi-species, a systemic parametric analysis based on a series of significant factors during electrochemical treatment (e.g., current density, treatment time, temperature, cathode position and concentration of lithium solution) reveals some important tendencies of ionic electromigration in concrete, which are supposed to guide the field application

The built environment impacts on route choice from home to school for rural students: A stated preference experiment

Introduction: Rural roads and built environment in China have been developed enormously, but it is not clear whether these roads fulfill the needs of school children as they need to travel long to school every day.Objective: It is crucial to understand the influencing factors of their travel mode choices to better design future country roads and built environment, aiming to promote physical activities of school children in a safe built environment.Method: This study thus attempts to explore the impacts of rural built environment attributes on children's school travel mode preferences. Eight rural built environment attributes are considered: distance from home to school; the number of intersections passed on the way to school; whether there are sidewalks/bicycle lanes; the traffic speed of school access routes; whether there are separation facilities between motor vehicles and non-motor vehicles; whether there are traffic lights and zebra crossings; availability of greenery such as lawns, flower ponds and street trees and whether there are shops on the way to school and at the school gate. Six hundred and thirty eight valid questionnaires were obtained through face-to-face interviews with school-age children in villages. A multinomial logit model was estimated to unravel the preferences and choices of rural school-age children in different models of school travel using the stated choice data.Results: All the eight attributes have significant impacts on rural children's school travel choices on foot, bicycle, electric bicycle or motorbike. And four rural road design attributes have significant effects on rural children's school travel by private cars. A travel path with pavements or bike lanes, few intersections, low traffic speeds, greenery and shops can facilitate children's school travels on foot or by bike. The conclusions can provide reference for the further upgrading planning, designing and construction of rural roads, as well as enriching the theory and practice of child-friendly villages construction.Design & Construction Managemen

Additive manufacturing of vascular stents

With the advancement of additive manufacturing (AM), customized vascular stents can now be fabricated to fit the curvatures and sizes of a narrowed or blocked blood vessel, thereby reducing the possibility of thrombosis and restenosis. More importantly, AM enables the design and fabrication of complex and functional stent unit cells that would otherwise be impossible to realize with conventional manufacturing techniques. Additionally, AM makes fast design iterations possible while also shortening the development time of vascular stents. This has led to the emergence of a new treatment paradigm in which custom and on-demand-fabricated stents will be used for just-in-time treatments. This review is focused on the recent advances in AM vascular stents aimed at meeting the mechanical and biological requirements. First, the biomaterials suitable for AM vascular stents are listed and briefly described. Second, we review the AM technologies that have been so far used to fabricate vascular stents as well as the performances they have achieved. Subsequently, the design criteria for the clinical application of AM vascular stents are discussed considering the currently encountered limitations in materials and AM techniques. Finally, the remaining challenges are highlighted and some future research directions are proposed to realize clinically-viable AM vascular stents. Statement of significance: Vascular stents have been widely used for the treatment of vascular disease. The recent progress in additive manufacturing (AM) has provided unprecedented opportunities for revolutionizing traditional vascular stents. In this manuscript, we review the applications of AM to the design and fabrication of vascular stents. This is an interdisciplinary subject area that has not been previously covered in the published review articles. Our objective is to not only present the state-of-the-art of AM biomaterials and technologies but to also critically assess the limitations and challenges that need to be overcome to speed up the clinical adoption of AM vascular stents with both anatomical superiority and mechanical and biological functionalities that exceed those of the currently available mass-produced devices.Biomaterials & Tissue Biomechanic

Quantifying the Uncertainty of Short-Term Vegetation Anomalies Detection Using Eo-Based Coarse-Resolution Vegetation Products

Satellite-based Earth Observation systems archived a variety of vegetation products during the last 50 years, which can reveal regional to global ecosystem dynamics across diverse spatiotemporal scales. The anomaly metrics such as Vegetation Condition Index (VCI) defined by comparing the current vegetation growth condition to historical average status based on long-term EO-based vegetation products were widely used to delineate abnormal vegetation variation exerted by either climatic or anthropogenic factors (e.g., droughts, wildfires). However, currently available long-term vegetation products may differ from each other in terms of sensors (observational platform or spectral bands), bio-physical definitions (e.g., NDVI, EVI, LAI, and VOD), spatiotemporal resolution, as well as the time-spans, which results in inconsistency across these vegetation products. Taking the VCI as an example, this study evaluated the uncertainty of vegetation anomalies detected based on different vegetation products over the middle reach of the Yangtze River by explicitly considering the effect of sensors, biophysical definitions, and time-spans. The preliminary results showed that VCI derived from NDVI products from different sensors (AVHRR vs. MODIS) induced significant inconsistent anomalies over most landscapes. The differences resulting from products with different biophysical definitions (NDVI vs. EVI, LAI, and VOD) are much lower than those from different sensors but still significant over specific areas. As for the time-spans, the 20-year NDVI based VCI presented a considerable reduction in variance over the study area on average compared to VCI calculated based on 5-year NDVI. In summary, caution should be taken when applying EO-based vegetation products for vegetation anomalies mapping, especially for quantitative assessment.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Optical and Laser Remote Sensin

Capturing and tracing the spatiotemporal variations of planktonic and particle-associated bacteria in an unchlorinated drinking water distribution system

The aperiodic changes in the quantity and community of planktonic and particle-associated bacteria have hampered the understanding and management of microbiological water quality in drinking water distribution systems. In this study, online sampling was combined with the microbial fingerprint-based SourceTracker2 to capture and trace the spatiotemporal variations in planktonic and particle-associated bacteria in an unchlorinated distribution system. The results showed that spatially, the particle load significantly increased, while in contrast, the quantity of particle-associated bacteria decreased sharply from the treatment plant to the distribution network. Similar to the trend of particle-associated bacterial diversity, the number of observed OTUs first slightly decreased from the treatment plant to the transportation network and then sharply increased from the transportation network to the distribution network. The SourceTracker2 results revealed that the contribution of particle-associated bacteria from the treatment plant decreased along the distribution distance. The spatial results indicate the dominant role of sedimentation of particles from the treatment plant, while the observed increases in particles and the associated bacteria mainly originated from the distribution network, which were confirmed directly by the increased contributions of loose deposits and biofilm. Temporally, the daily peaks of particle-associated bacterial quantity, observed OTU number, and contributions of loose deposits and biofilms were captured during water demand peaks (e.g., 18–21 h). The temporal results reveal clear linkages between the distribution system harboring bacteria (e.g., within loose deposits and biofilms) and the planktonic and particle-associated bacteria flowing through the distribution system, which are dynamically connected and interact. This study highlights that the spatiotemporal variations in planktonic and particle-associated bacteria are valuable and unneglectable for the widely on-going sampling campaigns required by water quality regulations and/or drinking water microbiological studies.Sanitary Engineerin

Built environment and travel behavior in rural areas: A scientometric literature review

With the rise of global urbanization, the rural built environment has undergone tremendous changes. As such, the rural built environment impacts on residents’ daily travel behavior is getting more researchers’ attention. To date, most of the research focuses on urban areas in developed countries. To understand the state-of-the-art of interplay between the rural built environment and travel behaviors and to identify future research directions, this study adopts a science mapping approach to identify the relevant topics, authors, journals, and countries of the research done. This study proceeds through bibliometric retrieval of articles from 2005, followed by scientometric analysis and qualitative discussion. 37 documents are found to compare urban and rural domains, with 28 on the rural built environment. Research gaps and the research trends are discussed, of which the main themes are multi-dimensional correlation comparison of rural transportation service systems and emerging transportation modes, the influence of rural social and cultural factors on travel behavior, and low-carbon sustainable transportation. This review provides empirical foundation for current state-of-the-art and identifies the future research directions, specifically for rural built environment impact on travel behavior.Design & Construction Managemen