Dissertations / Theses on the topic 'Artificial Rubies'

Artificial  spider  webs  are  a  challenge  for  the  special  effects  companies.   The natural  spider webs  are  displaying  incredible  mechanical  properties  combined with  a  low  density  and  a  high stickiness making them hard to reproduce. Throughout this project the aim is to produce artificial spider  webs  using  a specific  manufacturing  method,  pouring  a  mix  of  polymer  and  Naphtha  oil into  water  to  form  the  webs.   This  method  was  used  in  previous  cinematic applications  giving outstanding results for the artificial spider webs.  Unfortunately, due to the loss of it, the specific parameters,  tools and raw materials have to be found.  A material selection is given leading to a specific choice of thermoplastic polymers.  The selected material are then tested manually so they can be listed depending on the results obtained.  Finally, the most promising material seems to be TPU, thermoplastic polyurethane;  thanks to its excellent mechanical properties and good visual aspect.
Konstgjord  spindelväv  är  en  utmaning  för  specialeffektföretag.   De  naturliga spindelnäten visar  otroliga  mekaniska  egenskaper  i  kombination  med  låg densitet  och  hög  klibbighet  vilket gör  dem  svåra  att  reproducera.    Under hela  detta  projekt  är  målet  att  producera  konstgjord spindelväv med hjälp av en specifik tillverkningsmetod, hälla en blandning av polymer och naftaolja i vatten för att bilda näten.  Denna metod användes i tidigare filmiska applikationer och gav enastående resultat för de konstgjorda spindelnäten.  Tyvärr, på grund av förlusten av det, måste de specifika parametrarna, verktygen och råvarorna hittas. Ett materialval ges vilket leder till ett specifikt val av termoplastiska polymerer. Det valda materialet testas sedan manuellt så att de kan listas beroende på de erhållna resultaten.  Slutligen verkar det mest lovande materialet vara TPU, termoplastisk polyuretan; på grund av dess utmärkta mekaniska egenskaper och bra visuella aspekt.

Loss of speech is one important factor which contributes to a decrease of life quality for patients who undergo larynx removal following for example advanced laryngeal cancer. Several devices such as the electrolarynx and the tracheo-esophageal valve prosthesis (without oscillation) have been commercialized in order to restore speech. However, such voice restoration prosthesis are still limited for certain patients. The development of a new device using a valve of variable resistance entrained by a linear electromechanical transducer was investigated as a way to produce speech for patients with total laryngectomy (ablation of vocal folds). The concept was to undertake the design of a varying air flow resistance valve, built around existing Blom-Singer valves. The oscillating valve features a spherical head making it possible to block the opening in the wall between the trachea and the esophagus in a sinusoidal periodic fashion. A physical model of the vocal tract was built and used for preliminary in-vitro verification studies. The relationship between pressure and flow rate through the valve was determined from pressure measurements. The orifice discharge coefficient of the orifice was then calculated and the parameters of a variable resistor model were identified. Radiated sound pressure produced from the change in flow rate at the valve orifice was then compared to the original voice output to assess the accuracy of the design prototype. Results showed that the forced oscillating valve prosthesis model has lower power efficiency but can produce better sound quality than the electrolarynx.

Tire-pavement interaction is a dominant noise source for passenger cars and trucks above 25 mph (40 km/h) and 43 mph (70 km/h), respectively. For the same pavement, tires with different tread pattern and construction generate noise of different levels and frequencies. In the present study, forty-two different tires were tested over a range of speeds (45-65 mph, i.e., 72-105 km/h) on a non-porous asphalt pavement (a section of U.S. Route 460, both eastbound and westbound). An On-Board Sound Intensity (OBSI) system was instrumented on the test vehicle to collect the tire noise data at both the leading and trailing edge of the tire contact patch. An optical sensor recording the once-per-revolution signal of the wheel was also installed to monitor the vehicle speed and, more importantly, to provide the data needed to perform the order tracking analysis in order to break down the tire noise into two components. These two components are: the tread pattern and the non-tread pattern noise. Based on the experimental noise data collected, two artificial neural networks (ANN) were developed to predict the tread pattern (ANN1) and the non-tread pattern noise (ANN2) components, separately. The inputs of ANN1 are the coherent tread profile spectrum and the air volume velocity spectrum calculated from the digitized 3D tread pattern. The inputs of ANN2 are the tire size and tread rubber hardness. The vehicle speed is also included as input for the two ANN's. The optimized ANN's are able to predict the tire-pavement interaction noise well for different tires on the pavement tested. Another outcome of this work is the complete literature review on Tire-Pavement Interaction Noise (TPIN), as an appendix of this dissertation and covering ~1000 references, which might be the most comprehensive compilation of this topic.
PHD

A Rubber Balloon Soil Densitometer is one of the essential apparatuses in Geotechnical Engineering to measure the in-place volume of compacted soil to calculate the soil density. In 2019, some renowned institutions and organizations, Vattenfall, Luleå University of Technology, Uppsala University, Lund University, and HydroResearch AB, were involved in a research project. As a part of that research project, a small earth-rockfill dam was built in Älvkarleby, Vattenfall. During the construction of the experimental dam, to test the sufficiency of the degree of compaction in the core layers, the Rubber Balloon Soil Densitometer of the German company called Headquarters of Magdeburger Prüfgerätebau GmbH, in short HMP, was used. However, it was suspected that some of the HMP densitometer test results showed measured volumes of the excavated holes lower than the expectation. Hence, it aroused the necessity to check the correctness of the balloon test apparatus and its test procedure. This thesis topic aims to fulfill that necessity. The objective of this research is to determine whether the volumetric measurements achieved by this apparatus are accurate. If the volumes measured by this apparatus are inaccurate, it is crucial to find the reasons behind the inaccuracy. It is also essential to determine the inaccuracy causes and pursue the solution to obtain precision in volumetric measurement. This thesis topic is vital for engineers and researchers of civil engineering and other departments because concluding the research would help collect better soil density data using an HMP Rubber Balloon Soil Densitometer and other similar densitometers. All the laboratory works of this thesis were conducted at the Soil Laboratory of Luleå University of Technology. At the beginning of the laboratory work, a pit was excavated in a compacted mixed fine-grained silty sand type of soil inside a bucket to conduct a densitometer test. The actual volume of this pit was determined using the water replacement method. The HMP densitometer measured a volume of this pit smaller than its actual volume. Then, the apparatus itself was tested to evaluate its function. It was found that the plexiglass cylinder has different inner circular cross-sectional areas at different heights, which do not match the inner circular cross-sectional area mentioned in the HMP sticker on the plexiglass. As time passes, slight deformation of a plexiglass cylinder is normal and can happen because of temperature, applied pressure, and repetitive usage. The precision in percentage from the actual volume of a pit indicates the stuck air between the pit surface and the rubber balloon during a densitometer test. For engineering purposes, a precision in percentage smaller than one percent can be considered reasonable. The results showed that the actual volume of a pit should be at least around one liter to achieve precision in percentage from the actual volume of the pit smaller than about one percent. Additionally, pits with larger actual volumes have smaller precision in percentages from the actual volumes of the pits. The imperfection of the plexiglass cylinder has a lesser influence on larger pits during a densitometer test. Compacted coarse-grained soil can absorb the stuck air during a densitometer test because of having a sufficient quantity of pores. However, compacted fine-grained soil is so airtight that the soil can not absorb the stuck air. Transparent bowls and non-transparent bowls and a bucket were considered artificial pits of different sizes and shapes in compacted fine-grained soil, and densitometer tests were conducted with them. The results showed that the extended Ucsan bowl had the appropriate shape and size among these artificial pits. Because the average percentage of stuck air inside it was the smallest. However, the topmost diameter of an artificial pit or a real pit should be the same as the inner diameter of the metal ring of the HMP apparatus. Putting two stripes of industrial cleaning cloth perpendicularly inside an artificial or a real pit during a densitometer test was considered a solution to the stuck air problem. After applying this solution for the densitometer tests with all the artificial pits, the results showed that a real pit's appropriate shape and size with this solution should be similar to the extended Ucsan bowl. This was proved at the end of the laboratory work when a pit was excavated through the metal ring of the apparatus in a compacted mixed fine-grained silty sand type of soil inside a bucket to conduct densitometer tests. This pit was given a shape and size similar to the extended Ucsan bowl during excavation. This time, two industrial cleaning cloth stripes were placed perpendicularly inside the pit before the tests. The results showed that almost all the stuck air could be dissipated during a densitometer test by placing two stripes of industrial cleaning cloth perpendicularly inside a pit with a shape and size similar to the Ucsan bowl. During laboratory work, the HMP apparatus continuously measured volumes smaller than the actual volumes in all the densitometer tests.

Thesis (M.S.)--University of Akron, Dept. of Polymer Engineering, 2005.
"August, 2005." Title from electronic thesis title page (viewed 11/28/2005) Advisor, Lloyd Goettler; Faculty Reader, Avraam I. Isayev; Department Chair, Sadhan C. Jana; Dean of College, Frank N. Kelley; Dean of Graduate School, George R. Newkome. Includes bibliographical references.

Vibrations are very common phenomenon. It influences structures and generates acoustic noise which might be harmful to human beings. The vibration isolator was invented to reduce the effect from vibrations. However, the behavior of rubber material, which many vibration isolators are made of, is hard to predict. Consequently, vibration tests are needed to obtain the dynamic properties of rubber isolator.In this case, a six-year old LORD 2204-5 rubber isolator provided by Atlas Copco was tested. The aim of this paper is to obtain the FRF (Frequency Response Function) diagram which can describe the property of the rubber material. Moreover, the influence of aging of rubber material on the dynamic properties was studied.As the vibration test should simulate the working environment of the isolators that are both a static load from the structure and a dynamic force from the engine, a new excitation method was designed. The camshaft with the shape of an epitrochoid induced the sinusoidal signal of the isolator and the frame transferred the static load from the hydraulic machine. The artificial aging was performed in a hot air oven in 90°C for 42 hours, which according to Arrhenius equation should be equivalent to six years of natural aging. The vibration isolator was tested again after being aged.The obtained data showed that the aging process decreased the stiffness of the material. The results were corresponding with other studies regarding aging of rubber.

In recent years the use of inflatable dams has become more widespread throughout the world. Various people have done studies on the shape and membrane tension of these structures; however, only a few authors have considered dynamic behavior. Due to the nature of the applications and the material composition of these structures, a study considering the dynamic response of an inflatable dam is warranted.

In this study, the equation of motion for an air-inflated dam is derived, then solved using the Galerkin approximation method. The solution is performed for a one-term approximation and a two-term approximation, where both solutions use a sine function to approximate the deflected shape of the dam. Frequencies and amplitudes are calculated and presented in tables and plots for the first four modes, and three different values of the central angle of the dam. Comparisons to the results of other studies are presented at the conclusion of this study.
Master of Science

Rubber granulates, used at artificial grass pitches, pose a threat to the environment when leaking into the nature. As the granulates leak to the environment through rain water and snow clearances, they can be transported by rivers and later on end up in the marine life. Therefore, reducing the snow clearances to its minimum is of importance. If the snow clearance problem is minimized or even eliminated, this will have a positive impact on the surrounding nature. The object of this project is to propose a method for deciding when to remove snow and automate the information dispersing upon clearing or closing a pitch. This includes finding low powered sensors to measure snow depth, find a machine learning model to predict upcoming snow levels and create an application with a clear and easy-to-use interface to present weather information and disperse information to the responsible persons. Controlled experiments is used to find the models and sensors that are suitable to solve this problem. The sensors are tested on a single snow quality, where ultrasonic and infrared sensors are found suitable. However, fabricated tests for newly fallen snow questioned the possibility of measuring snow depth using the ultrasonic sensor in the general case. Random Forest is presented as the machine learning model that predicts future snow levels with the highest accuracy. From a survey, indications is found that the web application fulfills the intended functionalities, with some improvements suggested.

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A população de guará é considerada extinta em diversas regiões. A reprodução em cativeiro pode ser uma ferramenta importante para a conservação. Os objetivos foram desenvolver um protocolo alimentar e ambientação para a criação de filhotes de guará, intensificar a reprodução e aumentar o número de indivíduos em cativeiro, descrever as fases de desenvolvimento dos filhotes e desenvolver equações para estimar o crescimento. Os filhotes receberam três tipos de dietas: Dieta R (ração comercial), C (ração comercial e camarão) e P (ração comercial e peixe). A condição corporal e o peso dos filhotes foram obtidos diariamente e as medidas corporais a cada sete dias. A taxa de mortalidade na Dieta R foi 100% e nas Dietas C e P foram 0%. As médias dos pesos corporais e comprimentos dos ossos foram maiores com a Dieta P e as médias do comprimento da despigmentação do bico não foram diferentes com as Dietas C e P (P<0,05). A Dieta P apresentou maiores teores nutricionais. No Ano I a criação foi 100% artificial e no Ano II a criação em uma área do parque foi natural. Na criação artificial, o desenvolvimento dos membros e a condição corporal dos filhotes foram avaliados diariamente, e a pesagem a cada sete dias. A taxa de mortalidade foi menor e o número de nascimentos e a taxa de sobrevivência foram maiores durante a criação artificial. Todos os filhotes apresentaram ganho de peso (P<0,05), condição corporal boa e não foram observadas distrofias. As fases de desenvolvimento dos filhotes e o peso foram monitorados diariamente, e as mensurções da despigmentação do bico e ossos foram realizadas a cada sete dias. Os olhos abriram no dia 4,73 ± 0,12, no dia 6,31 ± 0,18 os filhotes se moveram dentro do ninho e no dia 15,3 ± 0,68 sairam do ninho. As médias do peso e das medidas dos ossos aumentaram (P<0,05). As médias da despigmentação do bico diminuiram (P<0,05). No 7º dia o bico começou a pigmentar e no dia 35º ficou completamente pigmentado. A correlação entre todos os parâmetros e os coeficientes de determinação das equações de regressão foram altos. A Dieta P foi considerada a melhor para a criação artificial. O protocolo proporcionou ambientação e alimentação adequadas, intensificou a reprodução e aumentou o número de guarás. Foi possível estabelecer as equações de estimativa de crescimento e descrever as fases de desenvolvimento dos filhotes. A pigmentação do bico foi considerada um parâmetro eficiente para estimar a idade.
The population of scarlet ibis is considered to be extinct in several regions. Captive breeding techniques are complementary tools for species conservation. The objectives were to develop a feeding protocol and an ambient environment for the rearing of scarlet ibis chicks, to intensify reproduction in captivity and increase the number of ibises in the colony, describe the developmental stages of chicks and develop growth estimation equations. The chicks were fed with three diets: Diet C (commercial feed), S (commercial ration and shrimp) and F (commercial ration and fish). The body condition and weight were taken daily, and the body measurements every seven days. The mortality rate under Diet C was 100%, and 0% under Diets S and F. The mean body weight and bones lengths were higher with Diet F and the mean length of the unpigmented portion of the beak did not differ among the diets (P<0.05). Diet F had higher nutritional contents. Rearing was artificial during year I and natural during year II at one of the areas of the park. The limbs development and body condition were evaluated daily, and the weight every seven days during artificial rearing. The mortality rate was lower and the number of births and survival rate were higher during artificial rearing. All of the young exhibited weight gain (P<0.05), good body condition and no dystrophies were observed. The development stages of chicks and the weight were monitored daily, and the measurements of the beak and bones were taken every seven days. The eyes opened on day 4.73±0.12, the nestlings moved within the nest on day 6.31±0.18 and left the nest on day 15.3±0.68. The means weight and measurements of the bones increased (P<0.05). The means of beak despigmentation decreased (P<0.05). The beak pigmentation started on day 7º and on day 35º was completely pigmented. The correlation between all parameters and the determination coefficients of regression equations were high. Diet F was found to be best for the artificial rearing. The artificial rearing protocol provided an adequate environment and feeding, intensified the reproduction and increased the number of scarlet ibises. Growth estimation equations were developed to assess the chicks growth and was possible to describe the developmental stages. Beak pigmentation was found to be a useful parameter for estimating the age.

Idrott är en stor bidragande faktor till social hållbarhet i Sverige, bland annat genom att främja folkhälsa, aktivera unga som gamla samt skapa gemenskap och sysselsättning. Enbart fotbollen aktiverar över 850 000 människor årligen i Sverige. En av anledningarna som möjliggör den höga aktiviteten är att en stor del av fotbollen sker på konstgräs. Konstgräs gör det möjligt att spela året om och ökar tillgängligheten. Dock beräknas konstgräsplaner vara den näst största källan till utsläpp av mikroplaster i Sverige. Därför har denna uppsats undersökt vilka barriärer som utgör de största hindren för aktörer i Lunds kommun att minska spridningen av gummigranulat från sina verksamheter. Den använda metoden har varit kvalitativa intervjuer med aktörer inom kommunen och föreningslivet, och en analys av materialet har gjorts utifrån Stephen Trudgills (1990) barriärer för arbete med miljöfrågor. Teorin utgår från att sex barriärer som behöver överkommas för att gå från problem till lösning, dessa barriärer är; enighet, kunskap, teknik, ekonomi, socialt, politisk. Utifrån intervjuerna var samtliga intervjupersoner tydliga med att konstgräs är viktigt för deras verksamheter och de var eniga om att det finns en situation med granulatspridning men det fanns tveksamheter kring problemställningen och omfattningen av problemet som grundades i osäker kunskap samt att befintlig kunskap inte kommuniceras ut bra nog. De presenterade en stor mängd tekniska lösningar som finns att tillgå men alternativen måste utvärderas i fråga om ekologisk och social lämplighet. Samtliga intervjupersoner såg ekonomi som en avgörande barriär och det finns potential att nyttja ekonomiska incitament mer för att påverka verksamheterna. Frågan om ansvar för granulatspridningen bör specificeras samtidigt som intervjupersonerna tryckte på vikten av samarbete och de visade en öppenhet för att dela med sig av erfarenheter och kunskap. Det uttrycktes behov av tydliga riktlinjer från beslutsfattare som stöd i den operativa verksamheten gällande hanteringen av konstgräsplaner. Det behövs dessutom mer forskning, gällande mikroplaster i allmänhet och konstgräs i synnerhet.
Sports are a big contributing factor to social sustainability in Sweden. It promotes public health, activates the population and creates community. Soccer alone activates over 850 000 people each year in Sweden. One of the reasons for the high activity is that a big part of soccer is played on artificial turf fields. Artificial turf makes it possible to play all year round and increases the accessibility. Artificial turf is however, calculated to be the second largest source of micro plastic emissions in Sweden. This essay has therefore studied what barriers constitute the biggest obstacles for stakeholders in the municipality of Lund to limit the emissions of granulates from the artificial turfs. The used method was qualitative interviews with participants from the municipality and soccer teams, and an analysis of the material was made based on a theory of barriers for working with environmental issues by Stephen Trudgill (1990). The theory consists of six barriers needed to go from problem to solution and the barriers are; agreement, knowledge, technology, economy, social and political. Based on the interviews the interviewees were all in agreement about the importance of artificial turf for their businesses and they were all aware of a situation with emissions of granulates, but there was doubt about the problem and the extent of the problem, which was based on lack of knowledge and poorly communicated knowledge. They presented plenty of technological solutions but these alternatives must be evaluated considering their ecological and social appropriateness. All interviewees considered economy to be an important barrier and there is potential to further use economic incitements. The question of responsibility needs to be specified, but the interviewees also highlighted the need for cooperation and showed an openness towards sharing experiences and knowledge. There was expressed opinions about the need for more political directives to support operative decisions. In addition, more research is needed, regarding micro plastics in general and artificial turf in particular.

Konstgräsplaner kan beaktas som en betydande utsläppskälla av mikroplaster. Fyllnadsmaterialet som används på konstgräsplaner kallas granulat och går under definitionen mikroplast. De som används främst på den svenska marknaden är SBR, TPE, EPDM och R-EPDM. Granulatet sprids främst via dagvattnet från konstgräsplaner som då riskerar att hamna i närliggande vattendrag. Tidigare studier har påvisat att granulatet kan urlaka toxiska ämnen som riskerar att förorena vattendragen. Vattenlevande organismer kan misstolka små partiklar som föda, vilket kan ge konsekvenser som bland annat förstoppning och svält. Ämnena som kan urlaka tillhör samlingsnamnet miljögifter och är stabila, toxiska, reproduktionsstörande och ackumulerande. Syftet med denna studie är att ge en beskrivning av vilka fyllnadsmaterial som används på konstgräsplaner i Gävle och undersöka hur dessa partiklar kan spridas samt identifiera åtgärdsförslag för att minska spridningen. Syftet är också att redovisa konstgräsplanernas dagvattenutlopp och vattendragens status för att redogöra för den potentiella miljöpåverkan som granulatet kan ge upphov till. Metoderna som använts i arbetet är litteraturstudie, personlig kommunikation, fältobservationer, kartsystem och figurer samt vattenprov.   Gavlefastigheter äger fem konstgräsplaner i Gävle kommun, vilka är Träffen IP, Gavlevallen, Nynäs IP, Sörby IP och Andersberg. På dessa planer används SBR- TPE- och R-EPDM-granulat. På planområdet förekommer dagvattenbrunnar och granulatet kan spridas till dessa genom ytavrinning vid höga regnflöden, snöplogning och smältvatten samt att spelarna får med sig partiklarna från planen. De flesta planer har dräneringssystem kopplat till dagvattenledningar som kan sprida urlakande ämnen till vattendrag. Dagvattenledningarna har utlopp i Testeboån, Bäckebrobäcken, Gavleån och Hemlingbybäcken. Granulatets fysikaliska egenskaper är en betydande roll om partikeln sedimenterar till botten eller om den kan transporteras med vattendraget. De konstgräsplaner som främst är i behov av åtgärder för att minska spridningen av granulat är Sörby, Anderberg och Nynäs.   Vattendragens statusklassning uppnår ej god kemisk status och ämnen som förekommer i förhöjda halter varierar beroende på vattendrag. Enligt tidigare studier kan flera av dessa ämnen urlaka från granulatet, vilket innebär att det finns en risk för ett tillskott av dessa ämnen om spridning sker.
Artificial turfs have been shown to be a significant source of microplastics. The filling material used on artificial turf is called granules and are under the definition microplastic. There are different kinds of granules on the Swedish market, these are SBR, TPE, EPDM and R-EPDM. The granules spread mainly through stormwater from artificial turf, which may then end up in nearby streams. Previous studies have shown that the granules can release toxic substances that risk contaminating the water. Aquatic organisms can misinterpret microscopic particles as food, which can cause consequences such as constipation and starvation. The substances that may leach from the granules belongs to the collective name environmental toxins and are stable, toxic, reproductive and accumulative.   The purpose of this study is to provide a description of the filling material that are used in artificial turfs in Gävle, investigate how these granules can spread and then identify suggestions to reduce the spread. The purpose is also to present the artificial turf's stormwateroutlets and water status to describe the potential environmental impact that the granulate may cause. The methods used in this work are literature studies, personal communication, field observations, map systems and figures and water samples.   Gavlefastigheter owns five artificial turfs in the municipality of Gävle which are Träffen IP, Gavlevallen, Nynäs IP, Sörby IP and Andersberg. These turfs use SBR- TPE and R-EPDM granules. There are open water wells on every turf area and granules can spread to these by surface water at intensive rain, snow plowing and meltwater and with the players when they leave the turf. Most turfs have drainage systems connected to stormwater pipelines that can spread leachable substances to water. The water pipelines have outlets in Testeboriver, Bäckebrostream, Gavleriver and Hemlingbystream. The physical properties of the granules have a significant effect if the particle sinks to the bottom or if it is transported along with the water. The artificial turfs that are primarily in need of taking actions to reduce the spread of granules are Sörby, Anderberg and Nynäs.   The waters do not achieve good chemical status and substances that occur at high concentrations varies depending on the kind of water. According to previous studies, several of these substances may leach from the granules which means that there is a risk of a contribution of these substances if spreading occurs.

博士
國立清華大學
化學工程研究所
84
In this study, we perform surface modification of silicone rubber (SR) with various vinyl monomers via plasma-induced graft coplymerization (PIP). The surface properties of modified SR such as functional groups, grafted amount, hydrophilic/ hydrophobic, surface morphology and biocompatibility are discussed before and after modification. Some appropriate ledaquate monomers are selected to prepare a heterobifunctional membrane. Furthermore, this membrane is highly promising for clinical ophthalmology. The high gas permeability, high transparent and high strength material-SR membrane was used as a substrate. Surface modification of SR was performed with plasma induced graft copolymerization with vinyl monomers such as acrylic acid (AA), 2-hydroxyethyl methacrylate (HEMA), and 2-methacryloyloxy ethylphosphorylcholine (MPC).In addition,the surface properties were characterized with an attenuated total reflection/fourier transform infrared (ATR-FTIR), element spectra for chemical analysis (ESCA), secondary ion mass spectra (SIMS), scanning electronic microscope (SEM) and contact angle meter. In vivo results of the heterobifunctional membrane surface of a modified silicone membrane indicated that inert splinting would aid in the successful corneal wound healing in a huge (7.0 mm) full-thickness defect, which is highly promising for clinical applications. Posterior synechiae frequently occurs after operation. Such a this problem can be resolved by pMPC grafting the membrane''s lowerside surface. Also, the characteristics of in vitro epithelial affinity were not verified by epithelial growth over the membrane through this in vivo study. Moreover, the host cornea could not bind with the implant membrane. Therefore, the implanted membrane finally dislodged several months after post-operative surgery. Above difficulties can hopefully be resolved by using this novel material. Furthermore, a permanent artificial cornea can hopefully made for future ophthalmological applications.

Διερευνώνται επιμέρους θέματα διαχείρισης παράκτιων υδροφορέων που αφορούν στην διασφάλιση της αειφορίας των υπόγειων αποθεμάτων μέσω (α) της προστασία τους έναντι στην υποβάθμιση της ποιότητάς τους που μπορεί να προέλθει από τη διείσδυση του θαλασσινού νερού και από ανθρωπογενείς δραστηριότητες και (β) της διασφάλισης της κάλυψης των αναγκών σε υπόγειο νερό κατά τις περιόδους αυξημένης ζήτησης. Η διερεύνηση βασίζεται στη χρήση δύο αριθμητικών μοντέλων υπόγειας ροής που λαμβάνουν υπόψη τις διαφορές πυκνότητας μεταξύ γλυκού και αλμυρού νερού και περιλαμβάνει τα ακόλουθα: Παρουσιάζεται ο τρόπος με τον οποίο διατυπώνονται και επιλύονται οι εξισώσεις που περιγράφουν την υπόγεια ροή υπό την επιρροή διαφορών πυκνότητας σε δύο ευρέως χρησιμοποιούμενα αριθμητικά μοντέλα, που είναι το μοντέλο SEAWAT-2000 (Langevin et al., 2003) και το μοντέλο SUTRA v2.2 (Voss & Provost, 2010). Βάσει των ανωτέρω και της εμπειρίας που αποκτήθηκε από την παράλληλη εφαρμογή τους, οι δύο κώδικες αξιολογούνται συγκριτικά και διατυπώνονται κριτήρια, στα οποία μπορεί να βασιστεί η επιλογή του κατά περίπτωση προσφορότερου κώδικα. Γίνεται η ρύθμιση αριθμητικού μοντέλου, το οποίο είναι βασισμένο στον κώδικα SEAWAT-2000, για τον παράκτιο υδροφορέα του Γλαύκου π., ο οποίος βρίσκεται στα νότια της πόλης των Πατρών και αποτελεί σημαντικό υδατικό πόρο για την περιοχή. Η ρύθμιση του μοντέλου βασίζεται σε μετρήσεις της υπόγειας στάθμης που προέρχονται από ένα σχετικά πυκνό δίκτυο γεωτρήσεων παρατήρησης το οποίο όμως έχει χρονικά περιορισμένη διάρκεια λειτουργίας. Το δίκτυο κατασκευάστηκε στα πλαίσια του προγράμματος INTERREG Ελλάδα – Ιταλία, 2000 – 2006, σε συνεργασία του Εργαστηρίου Υδραυλικής Μηχανικής του Πανεπιστημίου Πατρών και της Δημοτικής Επιχείρησης Ύδρευσης και Αποχέτευσης της Πάτρας (Δ.Ε.Υ.Α.Π.) και ολοκληρώθηκε στα μέσα του 2008. Η διαδικασία ρύθμισης του μοντέλου περιλαμβάνει τα εξής: (α) Τη συστηματική οργάνωση, συνδυασμό και αξιολόγηση των διαθέσιμων πληροφοριών σε λογισμικό συστημάτων γεωγραφικών πληροφοριών. (β) Την εφαρμογή υδραυλικών και στατιστικών μεθόδων σε συνδυασμό με την τροποποίηση και εφαρμογή μεθόδων αριθμητικής προσομοίωσης αντλητικών δοκιμών για τον προσδιορισμό των υδραυλικών χαρακτηριστικών του υδροφορέα. (γ) Τη συνδυαστική ανάλυση υδρολογικών δεδομένων και χρονοσειρών της υπόγειας στάθμης για την εκτίμηση των συνιστωσών του υδρολογικού ισοζυγίου. (δ) Τον καθορισμό κατάλληλων κριτηρίων αξιολόγησης των προσομοιώσεων. (ε) Την εμπειρική ρύθμιση των παραμέτρων του μοντέλου, η οποία επειδή έγινε παράλληλα με την συλλογή των μετρήσεων της υπόγειας στάθμης πραγματοποιήθηκε για δύο περιόδους, κατ’ αρχήν για την περίοδο 2008-2010 και εν συνεχεία για την περίοδο 2010-2012 και (στ) την εκτέλεση προσομοιώσεων Monte Carlo για την πραγματοποίηση καθολικής ανάλυσης ευαισθησίας (global sensitivity analysis, βλ. Saltelli et al., 2004) και τη διερεύνηση ύπαρξης περισσοτέρων συνδυασμών των τιμών των παραμέτρων του μοντέλου που οδηγούν σε παρόμοια αποτελέσματα (equifinality thesis, Beven, 2006). Από τη ρύθμιση του μοντέλου με τη βοήθεια των μετρήσεων της υπόγειας στάθμης που συλλέχτηκαν με το δίκτυο παρατήρησης προέκυψαν πληροφορίες για τους μηχανισμούς εμπλουτισμού του υδροφορέα στις διάφορες περιοχές, κάτι που είναι σημαντικό για τη διαχείρισή του. Το ρυθμισμένο μοντέλο του παράκτιου υδροφορέα του Γλαύκου χρησιμοποιήθηκε για την εξέταση θεμάτων διαχείρισης του υδροφορέα: (α) Προσδιορίστηκαν οι ζώνες τροφοδοσίας των γεωτρήσεων της ΔΕΥΑΠ με χρήση του κώδικα MODPATH v3 (Pollock, 1994) και εκτιμήθηκε η τρωτότητα αυτών των γεωτρήσεων. Διαπιστώθηκε ότι οι γεωτρήσεις που βρίσκονται κοντά στην κοίτη του Γλαύκου, όπως συμβαίνει με πολλές από τις γεωτρήσεις της ΔΕΥΑΠ, αντλούν σχεδόν αποκλειστικά νερό που προέρχεται από τον ποταμό. Έτσι είναι δυνατόν να προσβληθούν από ρυπάνσεις του νερού του ποταμού καθώς επίσης και από ανθρωπογενείς δραστηριότητες στις παρόχθιες ζώνες. (β) Εκτιμήθηκε ο κίνδυνος διείσδυσης θαλασσινού νερού σε περίπτωση εμφάνισης περιόδων ξηρασίας, για δύο διαφορετικά σενάρια αντλήσεων: ένα σύμφωνα με το σημερινό καθεστώς χρήσης του υπόγειου νερού και ένα για την αύξηση των αντλήσεων κατά 50%. Διαπιστώθηκε ότι για ξηρασία διάρκειας τεσσάρων ετών και αύξηση των αντλούμενων ποσοτήτων τα φαινόμενα υφαλμύρισης θα είναι έντονα. Με την επάνοδο όμως των μέσων υδρολογικών συνθηκών ο υδροφορέας ανακάμπτει. (γ) Για συνθήκες ξηρασίας εξετάστηκε η αποτελεσματικότητα του τεχνητού εμπλουτισμού για τον περιορισμό της διείσδυσης του θαλασσινού νερού. Ως μέθοδος εμπλουτισμού εξετάστηκε η εποχιακή αύξηση της στάθμης του νερού στον ποταμό με τη βοήθεια φουσκωτών φραγμάτων (βλ. Κωτσοβίνος, 1999). Διαπιστώθηκε ότι με τη μέθοδο αυτή μπορεί να επιτευχθεί σημαντική αύξηση των υπόγειων αποθεμάτων. Τέλος, εξετάζεται ως μέτρο προστασίας έναντι της διείσδυσης του θαλασσινού νερού η τεχνική των υπόγειων φραγμών. Επειδή στις μελέτες της τεχνικής αυτής που έχουν παρουσιαστεί στη βιβλιογραφία (π.χ. Luyun et al., 2011) έμφαση δίνεται μόνο στην επιρροή των γεωμετρικών χαρακτηριστικών των φραγμών (απόσταση από την ακτή, βάθος φραγμού), έγινε στην παρούσα εργασία συστηματική διερεύνηση της συναρτησιακής σχέσης ανάμεσα στην αποτελεσματικότητα της μεθόδου και τα χαρακτηριστικά τόσο των φραγμών όσο και του υδροφορέα (υδραυλική αγωγιμότητα, ανισοτροπία, υδρομηχανική διασπορά, παροχή γλυκού νερού προς τη θάλασσα, αντλήσεις στην παράκτια ζώνη, υλικό κατασκευής του φραγμού). Η διερεύνηση έγινε με τη βοήθεια του αριθμητικού μοντέλου SUTRA 2.2 (Voss and Provost, 2010), για δύο τύπους υπόγειων φραγμών: τους διαφραγματικούς τοίχους και τα υπόγεια φράγματα. Δίδονται διαγράμματα και αναλυτικές σχέσεις με χρήση αδιάστατων μεταβλητών και για εύρος τιμών των μεταβλητών αυτών που μπορούν να χρησιμοποιηθούν για τη διαστασιολόγηση φραγμών σε εφαρμογές πεδίου. Βάσει των αποτελεσμάτων που προκύπτουν από τη διερεύνηση της προαναφερθείσας συναρτησιακής σχέσης και χρησιμοποιώντας και το μοντέλο του Γλαύκου, εξετάστηκε η αποτελεσματικότητα της κατασκευής ενός φραγμού περιορισμένου μήκους στον υδροφορέα. Διαπιστώθηκε ότι πέραν του περιορισμού της διείσδυσης αλμυρού νερού σε περιόδους ξηρασίας που επιτυγχάνεται, ο φραγμός επιταχύνει την υποχώρηση της αλμυρής σφήνας όταν επανέλθουν οι συνήθεις υδρολογικές συνθήκες.
In the present study coastal aquifer management issues are investigated. These issues concern measures which ensure the sustainability of the coastal groundwater and particularly: (a) protective measures against the degradation of groundwater caused by saltwater intrusion and human activities and (b) measures allowing the availability of sufficient volumes of fresh groundwater during periods of high demand. The investigation is based on the application of two numerical codes, which are suitable for simulating the groundwater flow under the influence of density differences. The investigation procedure is as follows. The application of the equations of groundwater flow with density differences and transport, the limitations and the advantages are presented for two widely used numerical models, the SEAWAT-2000 code (Langevin et al., 2003) and the SUTRA v.2.2 code (Voss & Provost, 2010). Based on the analysis above and on the experience acquired through the parallel use of the two codes, basic criteria are derived that allow for the selection of the code that best suits the needs of a certain problem. The investigation focuses on the Glafkos coastal aquifer, which is located at north Peloponnese (Greece), south of the city of Patras and is an important source of freshwater for the region. For this aquifer the SEAWAT-2000 code is implemented and calibrated. The model calibration is based on groundwater level time series that were registered by a relatively dense monitoring network, whose operation time, however, is limited. The network of the monitoring wells was constructed during 2007-2008 in cooperation of the Hydraulic Engineering Laboratory (Department of Civil Engineering, University of Patras) and the Municipal Enterprise of Water Supply and Sewage of Patras (DEYAP), in the frame of the project INTERREG IIIA GREECE-ITALY. The calibration procedure is based on: (a) The application of a G.I.S. system to organize, combine, analyse and evaluate the available information. (b) The application of hydraulic and statistical methods combined with the modification and application of pumping tests simulation methods, for the estimation of the hydraulic parameters of the coastal aquifer. (c) The combined analysis of hydrological data and groundwater level time series for the estimation of the aquifers water budget components. (d) The establishment of appropriate criteria for the evaluation of simulation results. (e) The empirical calibration of the model is performed for two periods, i.e. the period 2008-2010 and the period 2010-2012. This procedure is due to the availability of the groundwater level time series which were registered parallel to the model calibration. (f) The application of the Monte-Carlo method in order to investigate the probability that different combinations of model parameters give similar or better simulation results. The model calibration led to a better understanding of the aquifers recharge mechanisms which is crucial for the development of a groundwater management policy and the implementation of a management plan. The calibrated groundwater model of the Glafkos coastal aquifer is used for the investigation and evaluation of coastal aquifer management applications: (a) The capture zones of the municipal production wells are delineated by applying the MODPATH v3 code (Pollock, 1994). It is found out that the production wells that are located close to the Glafkos River, as it is the fact for the majority of the municipal production wells, pump water that originates almost exclusively from the river. Consequently, polluted water from the river or polluting human activities close to the riverbank can affect the quality of the pumped water. (b) The saltwater intrusion risk is estimated, in case of a prolonged drought period. Two cases are investigated; the first considers the current pumping rates of groundwater while the second considers a 50% increased pumping. It is found out that a four-year drought period combined with an increase of the groundwater exploitation will lead to significant saltwater intrusion problems. (c) The applicability and effectiveness of in-channel artificial recharge with the use of rubber dams, as a countermeasure against the saltwater intrusion, which may be induced by a four-year drought period, is investigated. It is found that the method is applicable and effectively reduces the intrusion of saltwater. Further it increases the groundwater storage in the aquifer. Finally, the construction of a cutoff wall which covers only a small part of the aquifers width, is evaluated as a countermeasure to saltwater intrusion problems which may arise in Glafkos coastal aquifer. Due to the fact that existing studies on the technique of the subsurface barriers focus only on the influence of the geometrical characteristics of barriers covering the whole width of the aquifer, a systematic investigation is curried out on the functional relationship between the effectiveness of the barriers and all the parameters influencing it, i.e. the geometrical characteristics of the barriers, the aquifer parameters (the hydraulic conductivity, anisotropy, hydromechanical dispersion, groundwater flow towards the sea) and the pumping rate. The investigation is curried out by the use of the finite element code SUTRA v.2.2 and concerns two types of barriers; the subsurface dams and the cutoff walls. The results include graphs and functional relationships for the assessment of the effect of subsurface dams and cutoff walls and the design of such structures. The results are presented in terms of dimensionless variables, with ranges suitable for field applications. Based on these results, a cutoff wall of small width is designed for the Glafkos coastal aquifer. Its effectiveness is evaluated by applying the calibrated SEAWAT-model of the coastal aquifer. It is shown that the cutoff wall not only reduces the saltwater intrusion during drought periods, but also it reduces the retreat time of the saltwater front under normal hydrological conditions.