Thesis (MEng)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The Berg River is one of the largest rivers in the winter rainfall area of the Western Cape and is one of the most important water supply sources of the area. The Riviersonderend-Berg system needs to be expanded in order to meet increasing water demands of the Greater Cape Town (GCT) region. The implementation of future schemes will remove additional fresh water from the Berg River main stem, which will give rise to increased nutrient levels and higher salinity in the water. A water quality information system (WQIS) has been proposed to benefit the management of water resources, the flow quantity and the quality of the water. A part of this WQIS will be a water-quality simulation model that characterizes the water quality situation and is able to predict water quality responses to future implementations, as well as simulate different scenarios that can be used for management purposes. The objective of this study is to represent the water quality situation of the Berg River in a simulation model by implementing, testing and verifying a water quality simulation model, and assembling a hydraulic and water quality database suitable to meet foregoing objectives. This study firstly examined the water quality variables of concern: pH, Total Dissolved Salts (TDS) and phosphates to develop an understanding of the water quality responses and causes of the main stem of the Berg River system. A thorough review of the available models has been undertaken in the light of certain selection criteria, before determining that DUFLOW would be an acceptable model for this study. The water quality variables that have been modelled are TDS, Phosphates as P04, Oxygen and Temperature. As no predefined module simulating temperature, TDS and COD was included; these algorithms, describing the processes of these water quality variables have been additionally coded. The coding was possible, as DUFLOW' s water quality module consists of an open structure. The predefined water quality module was simplified to only include the water quality process algorithms, for water quality variables where data was available. Unfortunately, phosphates were mainly simulated on advection, and the influence of all the additional processes could not be assessed. All data gathering and preparation for the model had to be completed before commencing the model configuration. This included information on cross-sections, historical flow records, bridges and weirs for the hydraulic component ofDUFLOW. For the water quality module, information on historical grab samples has been obtained and 'infilled' to provide daily time series. To simulate the water quality in a river as accurately as possible, the flow simulation needs to be accurate. Ungauged subcatchment runoff was added to the simulation model to improve the correspondence between the simulated and the measured flow. Calibration of the water quality part of DUFLOW was completed by adjusting the different parameters after a sensitivity analysis. The model was verified by using a different time period than for the configuration, to ensure that an independent data set has been used. After configuring, calibrating and verifying the model, the applicability of the model could be tested for different scenario runs. Three scenarios were chosen according to real situations: • a short term effluent spill, with and without water releases from an upstream source (either Skuifraam Dam or Voëlvlei Dam); • the impact on the flow and water quality situation of the river when an upstream dam is built; • a long term management control scenario, that analyses load or concentration releases into the river according to limitations upstream and downstream of the discharge location. The scenario analysis provides an opportunity to assess the applicability of DUFLOW to simulate real time management and operational issues in a river and to aid in management decisions. / AFRIKAANSE OPSOMMING: Die Bergrivier is een van die grootste riviere in die winterreënvalgebied van die Weskaap en is een van die mees belangrike waterverskaffingsbronne in die area. Die Riviersonderend-Bergrivier-stelsel moet uitgebrei word om aan die groeiende waterbehoefte van die groter Kaapse Metropolitaanse Area te voldoen. Die implementering van toekomstige skemas sal addisionele vars water uit die hoof-loop van die Bergrivier onttrek, wat tot hoër voedingstof-vlakke en soutgehalte in die water sal lei. 'n Waterkwaliteitsinformasiestelsel (WQIS) sal van nut wees om die vloei-omvang en waterkwaliteit van waterbronne te bestuur. 'n Deel van die WQIS sal 'n waterkwaliteit-simulasiemodel wees, wat die waterkwaliteitsituasie sal kan ontleed, waterkwaliteit-reaksies op toekomstige implementerings kan voorspel, asook verskeie scenarios vir bestuursdoeleindes kan simuleer. Hierdie studie behandel spesifiek die waterkwaliteitsveranderlikes pH, totale opgeloste soute, fosfate, temperatuur en suurstof om 'n begrip te ontwikkel van die waterkwaliteitsreaksies en oorsake van die hoofloop van die Bergriviersisteem. Die doelwit van hierdie studie is om die waterkwaliteitsituasie van die Bergrivier uit te beeld deur die implementering, toets en kalibrasie van 'n waterkwaliteit-simulasie model, asook die insameling van hidrouliese- en waterkwaliteitsdata om aan bogenoemde doelwitte te voldoen. 'n Reeks beskikbare modelle is deeglik ondersoek voordat besluit is dat die DUFLOW model 'n gepaste model vir hierdie spesifieke studie is. Die keuse was gebaseer op spesifieke vereistes wat as belangrik beskou is deur potensiële bestuursgeorienteerde gebruiksgroepe. Die waterkwaliteitsveranderlikes wat gemodelleer is, is totale opgeloste soute, fosfate as P04, suurstof en temperatuur. Omdat geen voorgegewe temperatuur-, TDS- en COD modules in die model ingesluit is nie, is die algoritmes wat die prosesse van hierdie waterkwaliteitsveranderlikes beskryf, addisioneel gekodeer. Die kodering is moontlik gemaak deur die oop struktuur van DUFLOW se waterkwaliteitsmodule. Die voorgegewe waterkwaliteitsmodule is vereenvoudig om alleenlik die waterkwaliteit proses-algoritmes in ag te neem wanneer data vir waterkwaliteitsveranderlikes beskikbaar was. Ongelukkig is die fosfate hoofsaaklik op beweging gesimuleer, en die invloed van alle addisionele prosesse kon nie getoets word nie. Alle data-insameling en -voorbereidings vir die model moes voltooi word, voordat begin kon word met die opstel van die simulasie-model. Dit het inligting oor dwarssnitte, historiese vloeirekords, brik en keerwalle vir die hidrouliese komponent van DUFLOW ingesluit. Vir die waterkwaliteitsmodule is inligting van historiese bemonstering verkry en ingevulom 'n daaglikse tydreeks te verkry. Om die water-kwaliteit van 'n rivier so akkuraat as moontlik te simuleer, moet die vloei-simulasie redelik akkuraat wees. Ongemete sub-opvanggebied afloop is bygetel om die korrelasie tussen die gesimuleerde en gemete vloei te verbeter. Kalibrasie van die waterkwaliteitmodule van DUFLOW is voltooi deur die verskillende parameters te verstel na 'n sensitiwiteits-analise. Die model is geverifieer deur 'n ander tydperiode as die vir die opstel te gebruik, om sodoende te verseker dat Inonafhanklike data stel gebruik word. Na die opstel, kalibrasie en verifiering van die model, kon dit toegepass word vir verskillende bestuursscenanos. Drie scenarios is na aanleiding van werklike situasies gekies: 'n korttermyn uitvloeisel storting-situasie met en sonder loslatings van 'n stroomop bron (Of Skuifraamdam Of Voëlvleidam), die impak op die vloei- en waterkwaliteitsituasie van die rivier sou 'n dam stroomop gebou word. 'n langtermyn bestuurs-scenario waarin die lading en konsentrasies, veroorsaak deur die loslatings vanuit die dam na die rivier, ontleed word na aanleiding van beperkings stroomop en -af van die loslatingsplek. Die analise van die scenarios verskaf 'n geleentheid om die toepaslikheid van DUFLOW te ondersoek om werklike operasionele aangeleenthede te simuleer en om sodoende bestuursbesluite te vergemaklik.

Made available in DSpace on 2016-03-15T19:32:29Z (GMT). No. of bitstreams: 1 Helio Cardoso Pereira Jr.pdf: 1824752 bytes, checksum: 8d2ffb781a4283f3a9637649b3c2a686 (MD5) Previous issue date: 2011-08-11 / Fundo Mackenzie de Pesquisa / Studies have attempted to assess the quality of information provided by information systems in organizational context have been developed by several researchers, who were faced with the arduous task of identifying the various attributes that are related to the quality of information. This research sought to verify the existence of a gap in perception regarding the quality of accounting information received by information systems and quality expected by its users. We also sought to verify that the information systems used in organizations provide financial information about the quality necessary for good decision making. Methodological procedures were used for quantitative description, by a non-probability sample of the type of convenience that included 65 respondents. The instrument used was an electronic questionnaire survey type, containing predominantly closed questions, and issues in order to characterize the respondent and his company. In the processing of the data that were collected between February and May 2011 were used quantitative techniques such as descriptive statistics, mean test, reliability test, correlation and factor analysis. Some results indicate that users showed a difference of perception on some constructs related to quality of accounting information, among which: 1) accessibility, 2) amount of information, 3) completion, 4) credibility, 5) brevity, 6 ) consistency, 7) ease of operation, 8) without error, 9) interpretability, 10) objectivity, 11) relevance, 12) reputation, 13) security, 14) and opportunity 15) comprehensibility. The survey also indicated a strong correlation between the quality of accounting information and information system that provides this information. / Estudos buscando avaliar a qualidade das informações fornecidas por sistemas de informação, no contexto organizacional já foram desenvolvidos por diversos pesquisadores, que se depararam com árdua tarefa de identificar os vários atributos que estão relacionados à qualidade da informação. Com esta pesquisa buscou-se verificar a existência de um gap de percepção com relação à qualidade da informação contábil recebida pelos sistemas de informação e a qualidade esperada por seus usuários. Procurou-se também verificar se os sistemas de informação utilizados nas organizações fornecem informações contábeis com a qualidade necessárias para uma boa tomada de decisão. Foram utilizados procedimentos metodológicos de natureza quantitativa descritiva, mediante uma amostra do tipo não probabilística por conveniência que contemplou 65 respondentes. O instrumento de coleta utilizado foi um questionário eletrônico tipo survey, contendo questões predominantemente fechadas, além de questões visando caracterizar o respondente e sua empresa. No processamento dos dados que foram coletados entre de fevereiro e maio de 2011 utilizaram-se técnicas quantitativas como a estatística descritiva, teste de médias, teste de confiabilidade, correlação e análise fatorial. Alguns resultados indicam que os usuários demonstraram uma diferença de percepção quanto a alguns construtos relacionados à qualidade da informação contábil, dentre os quais destacam: 1) acessibilidade, 2) quantidade de informação, 3) completude, 4) credibilidade, 5) concisão, 6) consistência, 7) facilidade de operação, 8) sem erro, 9) interpretabilidade, 10) objetividade, 11) relevância, 12) reputação, 13) segurança, 14) oportunidade e 15) compreensibilidade. A pesquisa também indicou uma forte correlação entre a qualidade da informação contábil e o sistema de informação que fornece essa informação.

Die Qualitätssicherung von Forschungsdaten ist im Kontext offener Wissenschaft ein wichtiges Thema. Sollen geteilte Daten dabei unterstützen, Forschungsergebnisse nachzuvollziehen und die Nachnutzung von Daten ermöglicht werden, bestehen entsprechende Anforderungen an ihre Qualität. Bei Datenqualität und Qualitätssicherung im Kontext von Datenpublikationen handelt es sich allerdings um komplexe und divers verwendete Konzepte. Bislang wird die Qualitätssicherung von Datenpublikationen punktuell ausführlich beschrieben, jedoch fehlt eine Betrachtung, die die möglichen Maßnahmen systematisch beschreibt. Darüber, wie einzelne Maßnahmen bei Repositorien verbreitet sind, ist ebenfalls kaum etwas bekannt. In der Dissertation wird herausgearbeitet, wie Qualität und Qualitätssicherung für Forschungsdaten definiert und systematisiert werden können. Auf dieser Basis wird ein theoretischer Ansatz für die Systematisierung qualitätssichernder Maßnahmen erarbeitet. Er dient als Grundstruktur für die Untersuchung von Data Journals und Repositorien. Dazu werden Guidelines von 135 Data Journals und Zertifizierungsdokumente von 99 Repositorien analysiert, die das Zertifikat CoreTrustSeal in der Version 2017–2019 erhalten haben. Die Analysen zeigen, wie Datenqualität in Data Journal Guidelines und durch Repositorien definiert wird und geben einen Einblick in die Praxis der Qualitätssicherung bei Repositorien. Die Ergebnisse bilden die Grundlage für eine Umfrage zur Verbreitung qualitätssichernder Maßnahmen, die auch offene Prozesse der Qualitätssicherung, Verantwortlichkeiten und die transparente Dokumentation der Datenqualität berücksichtigt. An der Umfrage im Jahr 2021 nahmen 332 Repositorien teil, die im Verzeichnis re3data indexiert sind. Die Ergebnisse der Untersuchungen zeigen den Status quo der Qualitätssicherung und die Definition von Datenqualität bei Data Journals und Forschungsdatenrepositorien auf. Sie zeigen außerdem, dass Repositorien mit vielfältigen Maßnahmen zur Qualitätssicherung von Datenpublikationen beitragen. Die Ergebnisse fließen in ein Framework für die Qualitätssicherung von Datenpublikationen in Repositorien ein. / Quality assurance of research data is an important issue in open science. To enable transparency in research and data reuse, shared data have to meet quality requirements. However, the concepts of data quality and quality assurance are ubiquitous, yet elusive. Quality assurance practices have been researched for data publications in Data Journals, but not systematically for research data repositories. This dissertation elaborates how quality and quality assurance for research data can be defined and systematized. On this basis, a theoretical approach for quality assurance is developed. It is used for the analysis of quality assurance practices at data journals and research data repositories. For this purpose, guidelines of 135 data journals and certification documents of 99 repositories that have received the CoreTrustSeal certificate 2017–2019 are investigated. The analyses show how data quality is defined in data journal guidelines and by repositories and provide insight into repository quality assurance practices. The results informed a questionnaire that aims at analyzing prevalence of data quality assurance at research data repositories. The survey also covered aspects such open measures of quality assurance, responsibilities and transparent quality documentation. 332 repositories indexed in the re3data registry participated in the 2021 online survey. The results of this dissertations analyses indicate the status quo of quality assurance measures and definitions of data quality at data journals and research data repositories. Furthermore, they also show that repositories contribute to the quality assurance of data publications with a variety of measures. The results are incorporated into a framework for quality assurance of data publications at research data repositories.

本研究以科技接受模型為基礎，企圖整合資訊品質、系統品質和網站服務品質作為認知有用性和認知易用性的前置變項，期待了解三種品質構面對科技接受模型的影響效果，藉以探討民眾在使用電子化政府入口網時，會受到何種網站品質的影響，增加其使用意圖，以獲得對電子化治理的相關理解。另外本研究並嘗試以形成性指標的方式建構三種品質構面，以修正過去文獻誤用品質構面為反映性指標的情形。 透過線上問卷系統*蒐集1459位民眾的意見後，本文的研究結果顯示對認知易用性影響最大者為網站服務品質，認知有用性則受到認知易用性最大影響。對使用意圖有最大影響者為使用者的態度。三種品質的形成性指標對品質構面皆可達到顯著，在解釋上較為符合品質構面應為形成性指標的建構形式。文後並提供了對政府建置政府網站的實務建議，希冀能夠對未來政府網站建置提供參考。 / Based on technology acceptance model(TAM), this study develops a reaserach model that integrate information quality, system quality and website service quality as antecedents of perceived usefulness and perceived ease of use. The purpose of study is to explore how the three quality might influence technology acceptance model, and what might strengthen user intention on e-government portal website. In addition, this study develops quality constructs as “formative-indicators”rather than reflective ones to correct the misuse of some literatures. The model is then tested using a sample of 1459 users from online survey and analyzed the data using structural equation modeling. The results show that(1) website service quality(WSQ) have the most effects on ease of use(EOU), and that (2)ease of use have the most effects on usefulness(PU). They also demonstrate that (3)attitude predit user intention the most. The significance illustrate logically the relation between formative-indicators of three quality and the constructs. Implications of this study for research and practice are presented.

Záměrem předložené disertační práce je porozumět tomu, jak investoři v konkrétním společenském kontextu vnímají význam kvality informačních systémů. Ze studia literatury zabývající se přístupy a rámci hodnocení kvality informačních systémů vyplývá, že tato kvalita je obecně hodnocena z hlediska striktního přístupu. V této práci je ukázáno, že kvalitu informačního systému lze smysluplně pochopit použitím interpretačního paradigmatu a že kvalita informačního systému je definována společensky a ovlivňována kontextem tohoto systému. Studie byla zahájena průzkumem dvaceti libyjských organizací. Podrobnější data byla získána z případové studie dvou vybraných libyjských organizací působících ve veřejném sektoru. Při empirické analýze nashromážděných dat bylo využito rámce mnohočetné perspektivy, který zahrnuje hlediska teorie strukturalizace, pojem mnohočetných perspektiv a metodologii měkkých systémů. V práci se dospělo ke zjištění, že: a) kvalita informačních systémů je pojata šíře, než je tomu u tradiční definice kvality, b) mnohočetné perspektivy kvality informačních systémů jsou ovlivněny opakovanou interakcí mezi investorem a institucionálními vlastnostmi kontextu informačního systému a že c) rozdílné hodnoty v kulturním prostředí a vnějším kontextu ovlivňují rozsah působnosti investora a interakce v kontextu informačního systému. Ze závěru práce vyplývá, že společenská skladba mnohočetných perspektiv kvality informačního systému je ovlivněna strukturalizačními procesy mezi investory a vlastnostmi v kontextu informačního systému.