This diploma thesis focuses on the study of temperature dependence of -carrageen, hyaluronan of low molecular weight (250–450 kDa) and hyaluronan of high molecular weight (1 500–1 750 kDa) in aqueous solutions. The description of temperature depending changes in properties of these substance is based on rheological method. This work concentrates on the characterization of viscoelasticity through measurement of the storage (elastic) and loss (viscous) modulus using -carrageen and hyaluronan solutions of different molecular weights and different concentrations depending on temperature (20–50 °C, alternatively, in carrageen, 20–80 °C). The temperature dependence was further measured using an uncommon technique called high resolution ultrasonic spectroscopy (HR-US) which measured relative velocity of selected concentrations of -carrageen and hyaluronan of high molecular weight depending on the temperature of heating and cooling (20–80 °C). The measurements of temperature dependence were carried out for varied oscillation frequencies of rheometer sensor/frequency of ultrasonic waves. Knowledge of temperature dependence of the investigated substances may be applied in drug chemistry, primarily with respect to degradation due to high temperatures. The measured data gives information about sol-gel temperature and gel-sol temperature of carrageen.

[pt] Ondas acústicas, sônicas ou ultrassônicas, podem ser empregadas para a telemetria sem fio como alternativa a sistemas eletromagnéticos, transferindo dados e energia ao longo de um canal formado por uma ou mais camadas de sólidos elásticos ou fluidos acústicos. Um exemplo é a interrogação de sensores passivos através de uma parede metálica. Nesta configuração, pelo menos um transdutor acústico é fixado em um lado da parede (face externa), onde uma fonte de alimentação elétrica é disponível. No lado oposto (face interna), onde os sensores estão instalados, são fixados um ou mais transdutores. Na maioria das aplicações estes transdutores são cerâmicas piezelétricas que geram e recebem sinais ultrassônicos. Ondas acústicas ultrassônicas se propagam ao longo do sólido elástico, transferindo energia e dados entre as duas faces, possibilitando a alimentação e interrogação dos sensores. Este tipo de configuração pode ser empregado em aplicações onde o uso de penetradores elétricos ou ópticos não é recomendado. Entretanto, a resposta das piezocerâmicas pode sofrer influências de variações de temperatura e da própria deformação mecânica da parede metálica na qual são fixados. O presente trabalho procurou quantificar a influência da deformação mecânica e da variação de temperatura na comunicação entre dois transdutores piezocerâmicos ultrassônicos, aderidos à uma placa metálica por meio de adesivo epóxi. No estudo, tomou-se como parâmetro quantitativo o sinal S21, que é o logaritmo da razão entre a potência recebida pela saída do sistema (face interna da parede) pela potência transmitida pela entrada (face externa da parede). O trabalho apresenta comparações entre resultados experimentais e simulados através de um modelo numérico de elementos finitos desenvolvido no COMSOL Multiphysics. Os ensaios experimentais foram realizados com pastilhas piezocerâmicas circulares, do tipo PZT4, com diâmetro e espessura de 25 e 2 mm, respectivamente. Os transdutores foram fixados, de forma concentricamente alinhada e por meio de um adesivo epóxi, nas duas superfícies de uma placa de aço inoxidável AISI 316 L com 6 mm de espessura. O trabalho apresenta tabelas e funções para a amplitude do sinal S21 na frequência onde a transferência de potência é maximizada. Para os casos estudados, observou-se que a frequência ideal muda muito pouco com a temperatura ou a deformação da placa sobre a qual os transdutores são fixados, permanecendo com valores entre 0,988 e 0,995 MHz em todas as condições avaliadas. Em função da deformação da placa metálica, a amplitude do sinal S21 também variou muito pouco, de -3,70 para -3,14 dB, desde a condição indeformada da placa até a máxima deformação aplicada, que foi de 1250 (Micro)m/m. Quanto à variação com a temperatura, na faixa de 30 a 100 Graus C, mais uma vez observou-se apenas um pequeno aumento de 0,8 dB na amplitude do sinal S21. Entretanto, para temperaturas acima de 100 Graus C, o sinal passa a cair rapidamente. Em nenhuma das condições estudadas neste trabalho foi observado prejuízo na transferência de potência entre os transdutores, indicando que este tipo de comunicação pode ser uma alternativa robusta ao uso de penetradores elétricos. / [en] Acoustic, sonic or ultrasonic waves can be used for wireless telemetry as an alternative to electromagnetic systems, transferring data and energy along a channel formed by one or more layers of elastic solids or acoustic fluids. An example of this is the interrogation of passive sensors through a metallic wall. In this configuration, at least one acoustic transducer is attached to one face of the wall (external face) where electrical power supply is available. One or more transducers are also attached to its other side (internal face) where the sensors are installed. In most applications, these transducers are piezoelectric ceramics that generate and receive ultrasonic signals. Ultrasonic acoustic waves propagate along the elastic solid, transferring energy and data between both sides, which enables the power supply and interrogation of the sensors. This type of configuration can be used in applications where the use of an electrical or optical penetrator is not suitable. However, the response of piezoceramics may be affected by temperature variations and mechanical deformations of the metallic wall on which they are attached. The present work sought to quantify the influence of mechanical deformation and temperature changes on the communication between two ultrasonic piezo ceramic transducers, adhered to a metal plate by using an epoxy adhesive. The parameter used to quantify this influence was the S21 signal, which is the logarithm of the ratio between the power received from the output of the system (internal face of the wall) to the power transmitted by the input (external face of the wall). The work presents comparisons between experimental and simulated results obtained by using a finite element model developed through the commercial software COMSOL Multiphysics. In the configuration experimentally tested, two PZT-4 disks with diameter and thickness of, respectively, 25 and 2 mm were concentrically attached to both sides of a 6 mm thick, AISI 316 L stainless steel plate. Amplitudes of the S21 signal measured at the frequency where power transfer is maximized were obtained for different temperature and strain levels. Results for all of the evaluated conditions showed that the impedance matching frequency suffers little influence from temperature variations or strain in the plate on which the transducers are attached, having remained within a range from 0.988 to 0.995 MHz in all tests. As mechanical strains were applied to the metal plate, the amplitude of the S21 signal varied from -3.70 dB to -3.14 dB, from the undeformed condition to the maximum applied deformation (1250 (Micro)m/m). Regarding temperature changes, a small increase of 0.8 dB in the amplitude of the S21 signal was observed when increasing temperature from 30 C Degrees to 100 C Degrees. However, for temperatures above 100 C Degrees, the signal was found to quickly decay. None of the conditions studied in this work brought any impairment to the power transfer between the transducers, indicating that this type of communication can be a robust alternative to electrical penetrators.

Denna studie syftar till att undersöka hur ultraljudsutbildningar för ingenjörer köps in, vad de innehåller, hur de genomförs, utvärderas och vilka resultatutbildningarna leder till. Totalt intervjuades sex sjukhus runt om i Sverige där elva medicintekniska ingenjörer och fyra verksamhetschefer deltog. En kvalitativ metod användes i studien i form av semistrukturerade intervjuer som grund för att analysera frågeställningarna. Resultatet visade att utbildningar köps in i upphandling av nya ultraljudsmaskiner och genomförs under garantiåren. Utbildningarna hålls av leverantörerna och de brukar vara i två dagar. Effekterna av utbildningarna varierar och beror på vilket serviceavtal som sjukhusen har. Det saknas en formell modell för utvärdering och uppföljning, trots det faktum att det i årliga möten diskuteras hur utbildningarna har gått och vilka kompetenser som behövs. Resultatet från studien kan främst användas i syfte att skapa bättre utbildningar, underlätta kommunikationen mellan sjukhus och leverantör om vad kursen innebär, samt vad ingenjörerna föredrar för innehåll i kurser för att kunna utvecklas inom ultraljud. / This study aims to investigate how ultrasound training for engineers is purchased, including how it is carried out and evaluated, what the different courses contain and what result the courses lead to. Six hospitals around Sweden were interviewed, where eleven medical engineers and four business managers participated. A qualitative method was used in the study with semi-structured interviews as a basis for analysing the issues. The results showed that the training courses are purchased in the procurement of new ultrasound machines and are carried out during the warranty years. The suppliers hold the training courses, which are usually held for two days. The effects of training vary and depend on the service agreement that the hospitals have. There is no formal model for evaluation and follow-up, even though annual meetings discuss how the training has gone and what skills are needed. The results can mainly be used to create better training and improve communication between hospital and supplier about what the course entails and what the engineers prefer for the content of courses to develop in the area.

Quantification of inclusions is important since it is correlated to the steel’s fatigue properties. One method that could be further developed for detection of inclusions in steel is ultrasonic testing (UST). The aim of this study is to investigate what type of inclusions, in terms of size, morphology and chemical composition, that can be detected with 25 MHz UST, and what type of inclusion that cannot be detected. This was done by firstly scanning 74 steel samples with 25 MHz UST, and then fatigue test the same samples until fracture. The inclusion that caused the fracture was then analysed with microscopy and compared with the results from the 25 MHz UST. It was found that Mn-Mg-sulphides, Ca-sulphides, oxy sulphides and complex oxides are difficult to detect with 25 MHz UST. Globular oxides can be detected with 25 MHz UST, at least down to an area of 8300 μm2 and if they are not too fragmented due to rolling. The results indicate that oxy sulphide stringers can be detected with 25 MHz UST if the inclusion have oxides in direct contact with the steel matrix, rather than oxides encapsulated by sulphides. / Kvantifiering av inneslutningar är viktigt då det korrelerar med stålets utmattningsegenskaper. En metod som kan utvecklas för detektering av inneslutningar i stål är ultraljudstestning (UT). Syftet med den här studien är att undersöka vilken typ av inneslutningar, med avseende på storlek, morfologi och kemisk sammansättning, som kan detekteras med 25 MHz UT, och vilken typ av inneslutningar som inte kan detekteras. Detta gjordes genom att först skanna 74 stålprover med 25 MHz UT och sedan utmattningstesta samma prover tills de gick till brott. Inneslutningen som orsakade brottet analyserades sedan med mikroskopi och jämfördes med resultaten från 25 MHz UT. Det visade sig att Mn-Mg-sulfider, Ca-sulfider, oxisulfider och komplexa oxider är svåra att upptäcka med 25 MHz UT. Globulära oxider kan upptäckas, åtminstone ner till en area på 8300 μm2 och om den inte har blivit för fragmenterad av valsning. Resultaten indikerar att oxisulfider kan detekteras om oxiderna är i direkt kontakt med stålmatrisen, i stället för att oxiderna är inkapslade av sulfider.

Detta examensarbete fokuserar på utveckling och utvärdering av en ny metod för att räkna dubbelriktade personflöden inomhus med hjälp av Ultrasonic Time-of-Flight teknik. Projektets huvudsyfte är att skapa en kostnadseffektiv, strömsnål och integritetsvänlig lösning som är i linje med lagar som GDPR. Studien börjar med en kort genomgång av tillgängliga tekniker för personflödesmätning, men det blir tydligt att dessa tekniker brister i kraven för den önskade tekniken. Mot denna bakgrund framstår Ultrasonic Time-of-Flight som en lovande kandidat på grund av sin förmåga att detektera objekt och rörelseriktningar utan att samla in personligt identifierbar information. För att realisera detta projekt har ett utvecklingskit baserat på sensorn CH201 från Chirp Microsystems använts. Sensorns låga strömförbrukning och förmåga att mäta avstånd i ett brett synfält är det som är lovande i tekniken. Ett akustiskt hölje optimerar sensorernas synfält och minimerar störningar. Experimentdelen av arbetet inkluderar uppbyggnaden av en testmiljö där sensorernas förmåga att korrekt räkna individer och bestämma deras rörelseriktning testas. Resultaten från dessa tester visar på hög noggrannhet i detektering av enskilda individer som passerar, men har lägre noggrannhet då flera personer passerar samtidigt. Vidare diskuteras potentialen för att vidareutveckla systemet för att även kunna hantera större personflöden och mer komplexa scenarion, som flera personer som rör sig bredvid varandra i olika riktningar. En kritisk granskning av systemets prestanda under längre tidsperioder och i olika miljöer föreslås som framtida forskningsarbete för att ytterligare validera och förbättra tekniken. Sammanfattningsvis demonstrerar detta arbete potentialen hos tekniken som en säker och integritetsvänlig lösning för effektiv övervakning av personflöden. Med ytterligare utveckling och anpassning förväntas tekniken kunna uppfylla en ännu högre noggrannhet. / This thesis focuses on the development and evaluation of a new method for measuring bidirectional indoor people flows using Ultrasonic Time-of-Flight technology. The main purpose of the project is to create a cost-effective, low-power, and privacy-friendly solution that complies with laws like the GDPR. It begins with a short review of existing techniques for measuring people flow, concluding that these technologies do not support the goal of the new technology. Ultrasonic Time-of-Flight emerges as a promising candidate due to its ability to detect objects and directions of movement without collecting personally identifiable information. To realize this project, a development kit based on the CH201 sensor from ChirpMicrosystems has been used. The sensor’s low power consumption and ability to measure distances in a wide field of view are what made the technology promising. An acoustic enclosure optimizes the sensors’ field of view and minimizes interference. The experimental part of the work includes the construction of a test environment where the sensors’ ability to accurately count individuals and determine their direction of movement is tested. The results from these tests show high accuracy in detecting individual passersby but encounter more problems with multiple individuals simultaneously. Further discussions will explore the potential for developing the system to manage larger crowds and more complex scenarios, such as multiple people moving side by side in different directions. A critical review of the system’s performance over longer periods and in different environments is proposed as future research work to further validate and improve the technology. In conclusion, this work demonstrates the potential of the technology as a secure and privacy-friendly solution for effective monitoring of people flows. With further development and adaptation, the technology is expected to offer significantly better accuracy.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei / Poor machinability of hard-to-machine materials (such as advanced ceramics and titanium) limits their applications in industries. Ultrasonic-vibration-assisted grinding (UVAG), a hybrid machining process combining material-removal mechanisms of diamond grinding and ultrasonic machining, is one cost-effective machining method for these materials. Compared to ultrasonic machining, UVAG has much higher material removal rate while maintaining lower cutting pressure and torque, reduced edge chipping and surface damage, improved accuracy, and lower tool wear rate. However, physics-based models to predict cutting force in UVAG have not been reported to date. Furthermore, edge chipping is one of the technical challenges in UVAG of brittle materials. There is no report related to effects of cutting tool design on edge chipping in UVAG of brittle materials. The goal of this research is to provide new knowledge of machining these hard-to-machine materials with UVAG for further improvements in machining cost and surface quality. First, a thorough literature review is given to show what has been done in this field. Then, a physics-based predictive cutting force model and a mechanistic cutting force model are developed for UVAG of ductile and brittle materials, respectively. Effects of input variables (diamond grain number, diamond grain diameter, vibration amplitude, vibration frequency, spindle speed, and federate) on cutting force are studied based on the developed models. Interaction effects of input variables on cutting force are also studied. In addition, an FEA model is developed to study effects of cutting tool design and input variables on edge chipping. Furthermore, some trends predicted from the developed models are verified through experiments. The results in this dissertation could provide guidance for choosing reasonable process variables and designing diamond tools for UVAG.

Defects in a plastic floor material produced in Tarketts factory in Ronneby are causing waste of time and material since it is noticed too late in the production line. The objective of this thesis is to investigate if the nondestructive test method NAW®, which is developed by Acoustic Agree in Ronneby, can be a solution to find the defects at an earlier stage. Nondestructive testing mainly means what the name says; quality tests of a material can be made without causing any damage. One simple example of a nondestructive testing tool is the human eye. By looking at a product defects on the surface can be found. The method used in this thesis, NAW®, is a nonlinear acoustical method. By listening to the material, information about disturbances inside the material can be gathered and interpreted to get a picture of the quality status. Although by listening it does not in this case mean by a human ear but with special equipment since the sound used is high frequent ultrasound. For several material samples, experiments were made both for the references and with introduced defects. It was hard to get definitive results since, for example, even the results for the different reference samples were differing a lot. Nevertheless there are some results pointing in the same direction which means that there is still hope for the possibility to use NAW® as a tool in the production at Tarkett. One important problem in this work is the fact that the defect material is not actually a real defect material but an imitated one with defects made by hand in the experiments. This is a possible error and has to be considered in case of further experiments. Either the imitated defects have to be “improved” or, in the ideal case, real defective material from the factory should be used to get as reliable results as possible. / Defekter i golvmaterial i tillverkningen hos Tarkett i Ronneby orsakar slöseri med tid och material eftersom de upptäcks sent i produktionslinjen. Syftet med detta examensarbete är att undersöka om den oförstörande provningsmetoden NAW®, som utvecklats av Acoustic Agree i Ronneby, kan vara en lösning för att hitta defekterna på ett tidigare stadium. Oförstörande provning är helt enkelt materialprovning där föremålet som undersöks inte förstörs. Ett enkelt exempel på verktyg för oförstörande provning är ögat. Genom att undersöka ett föremål med synen kan man enkelt kvalificera ytan. Den metod som används i detta arbete, NAW®, är en olinjär akustisk metod. Genom att lyssna på materialet kan mycket information om störningar inuti materialet samlas ihop och tolkas för att få en bild av kvaliteten. För flera materialbitar har experiment genomförts både för referensmaterial och för material med imiterade defekter. Det var svårt att se entydiga resultat då exempelvis till och med resultaten för referensmaterialet var väldigt olika sinsemellan. Dock pekar vissa av resultaten åt samma håll vilket gör att hoppet lever kvar för att NAW® kan vara ett möjligt verktyg i produktionen hos Tarkett. Ett stort problem i arbetet var frånvaron av trovärdiga defekter. Defekterna tillverkades och introducerades i materialet för hand, och viss tveksamhet finns gällande likheten mellan imiterade och riktiga defekter. Detta ses som en möjlig felkälla och måste tas i beaktan för eventuellt fortsatt arbete. Antingen måste de imiterade defekterna ”förbättras” eller, som vore idealt, så kan riktigt defekt material från tillverkningen användas för att ge så trovärdiga och pålitliga resultat som möjligt.

Published Article / The design, manufacture and use of diaphragm valves in the minerals industry is becoming increasingly important since this sector is restricted from using excessive amounts of water for their operations. This forces a change in the flow properties of these devices from turbulent to laminar in nature and thus necessitates the characterization of these flows for future designs. Furthermore, diaphragm valves have a short service life due to a variety of reasons that includes the abrasive nature of the flow environment. This paper describes the activities of the Adaptronics Advanced Manufacturing Technology Laboratory (AMTL) at the Cape Peninsula University of Technology in the research and development of diaphragm valves using rapid prototyping technologies. As a first step, an experimental diaphragm valve was reverse engineered and retrofitted with ultrasonic transducers used in Ultrasonic Velocity Profiling (UVP) measurements. The use of this device enables measurements of velocity profiles to gain insight into the flow structure within the valve and the increased pressure losses generated within the valve. It also showed that components fabricated using the Z-Corporation machine could withstand the working environment of diaphragm valves. Research is now conducted on ultrasonic transducer placement in the device to further enhance the velocity profiling through the device. As a second step we produced a thin-walled stainless steel diaphragm valve using rapid prototyping technology and investment casting processes. A study of the durability of this device will be conducted and certain geometric and manufacturing aspects of this valve will be discussed.

Thesis (M.Tech.: Chiropractic)-Dept.of Chiropractic, Durban Institute of Technology, 2003 / Medial Tibial Stress Syndrome Type II (MTSS), otherwise known as shin splints, accounts for approximately 13% of injuries in American runners. Van Mechelen (1992) reported that 37-57% of recreational runners experience an injury over the course of a year, from which 54-75% of all injuries are caused by overuse. The American Medical Association defines shin splints as “pain and discomfort in the leg from repetitive activity on hard surfaces, or due to forceful, excessive use of foot flexors. The diagnosis should be limited to musculoskeletal inflammations excluding stress fractures and ischemic disorders.” (Thacker et al., 2002) Treatment protocols vary from biomechanical interventions (orthotics), to non-steroidal anti-inflammatory drugs and modalities such as ultrasound all with varying degrees of success (Noakes, 2001). Apart from therapeutic interventions it is the overriding symptom of pain, which patients are left with (Noakes, 2001). A therapeutic intervention called periosteal pecking has received increased interest with regards to symptomatic treatment of shin splints. Periosteal pecking is a form of *dry needling in which the tip of the needle contacts the periosteum (Raso,1997). The aim of this study is to establish the effect of periosteal pecking in the clinical setting with and against that of an established intervention, namely therapeutic ultrasound.

Thesis (M.Tech.: Chiropractic) - Dept. of Chiropractic, Durban Institute of Technology, 2003 1 v. (various pagings) / This study was a prospective, randomised, double blinded, placebo controlled, comparative clinical trial to establish the efficacy of therapeutic ultrasound and compare the effectiveness of the two waveforms of ultrasound in the treatment of myofascial pain syndrome.