An algorithm was developed to enable efficient segmentation of dimensionally-large objects into smaller components that can be fabricated within the given Rapid Prototyping (RP) machine workspace. The algorithm uses vertical and horizontal flat plane cuts, as well as feature-based volume decomposition. Due considerations were given to the optimisation of the surface accuracy, the build time, the strength and the number of segments generated by the segmentation process. A computer-aided design (CAD) application programme that interfaces with Unigraphics (UG) was also developed to allow import of objects in Standard Triangulated Language (STL) files into UG without loss of accuracy. In addition, the application software provides the functions that facilitate the implementation of the segmentation algorithm in UG. Two case studies were carried out using the algorithm in a Selective Laser Sintering (SLS) RP system. The resulting objects had properties that matched the research objectives with which the proposed algorithm was validated. / Singapore-MIT Alliance (SMA)

There were three poly-Si TFT made by ELA, SLS, and HREC. The HREC TFT had better reliability than ELA TFT and SLS TFT under AC and hot carrier stress. And the effect of bending in SLS TFT was more obvious then ELA TFT, it provide us a better choose to develop a flexible TFT LCD. In poly-Si TFT, the photon current would decrease if there was a grain boundary in the channel. In all parameters include both manufacture and measurement the HREC TFT had better behaviors than ELA TFT and SLS TFT. But there also some shortcomings we must overcome include we muse growth a heat-retaining layer extra and must etch it and the poly-Si/heat-retaining etch rate and so on.

Customized cellular material is a relatively new area made possible by advancements in rapid manufacturing technologies. Rapid manufacturing is ideal for the production of customized cellular structure, especially on the meso scale, due to the size and complexity of the design. The means to produce this type of structure now exist, but the processes to design the structure are not well developed. The manual design of customized cellular material is not realistic due to the large number of features. Currently there are few tools available that aid in the design of this type of material. In this thesis, an automated tool to design customized cellular structure is presented.

Individuals with various lower-limb neuromuscular and musculoskeletal impairments are often prescribed passive-dynamic ankle-foot orthoses (PD-AFOs) to compensate for impaired ankle muscle weakness. Several studies have demonstrated the beneficial effects of PD-AFOs on pathological gait, but few studies have examined the influence of the AFO stiffness characteristics on gait performance. One challenge to performing such studies is the difficulty of manufacturing custom AFOs with a wide range of controlled stiffness levels. However, selective laser sintering (SLS) is a well-suited additive manufacturing technique for generating subject-specific PD-AFOs of varied stiffness. Therefore, the overall goal of this study was to use SLS manufactured PD-AFOs to identify the relationships between AFO stiffness and gait performance in patients with various lower-limb neuromuscular and musculoskeletal impairments. Six subjects with unilateral impairments were enrolled in this study. For each subject, one subject-specific PD-AFO equivalent to the subject’s clinically prescribed carbon fiber PD-AFO (nominal), one 20% more compliant and one 20% more stiff were manufactured using SLS. Three-dimensional kinematic and kinetic data were collected from each subject while ambulating with each PD-AFO at two different speeds to allow a comprehensive biomechanical analysis to assess the influence of PD-AFO stiffness on gait performance. The results showed that in the compliant AFO condition, the AFO limb vertical ground reaction force (GRF) impulse during loading and the non-AFO limb medial GRF impulse during push-off decreased. In addition, the AFO limb braking GRF impulse during loading and the non-AFO limb braking GRF impulse in early single-limb stance decreased. Furthermore, in the compliant AFO condition, negative knee work during early single-limb stance increased while positive hip work in early swing decreased in the AFO limb. Overall, as AFO stiffness decreased, the AFO limb contributed less to body support and braking. In addition, a decreased medial GRF impulse coupled with an increased vertical GRF impulse during non-AFO single-limb stance suggests that walking stability may be compromised as AFO stiffness decreases. Thus, a tradeoff may exist between preserving stability and increasing net propulsion, which should be considered when assessing the mobility needs of individuals prescribed PD-AFOs as a result of various neuromuscular and musculoskeletal impairments. / text

This thesis provides investigation into the interaction between quartz lamp emitters and polyether ether ketone (PEEK) powder. Calculations and experiments concerning the conductivity and emissivity of the powder at various temperatures are performed. The thermal profile of the emitter on a flat powder bed is captured using thermal imaging. The effect of exposing a pile of powder to the emitter and the subsequent thermal gradient through the pile is measured and analyzed. Based on these results, ramifications for the application of these emitters to selective laser sintering (SLS) machines for processing high temperature polymers such as PEEK are discussed. / text

Topology optimization tools are useful for distributing material in a geometric domain to match targets for mass, displacement, structural stiffness, and other characteristics as closely as possible. Topology optimization tools are especially applicable to additive manufacturing applications, which provide nearly unlimited freedom for customizing the internal and external architecture of a part. Existing topology optimization tools, however, do not take full advantage of the capabilities of additive manufacturing. Prominent tools use micro- or meso-scale voids or artificial materials to parameterize the topology optimization problem, but they use filters, penalization functions, and other schemes to force convergence to regions of fully dense (solid) material and fully void (open) space in the final structure as a means of accommodating conventional manufacturing processes. Since additive manufacturing processes are capable of fabricating intermediate densities (e.g., via porous mesostructures), significant performance advantages could be achieved by preserving and exploiting those features during the topology optimization process. Towards this goal, a topology optimization tool has been created by combining homogenization with parametric smoothing functions. Rectangular mesoscale voids are used to represent material topology. Homogenization is used to analyze its properties. B-spline based parametric smoothing functions are used to control the size of the voids throughout the design domain, thereby smoothing the topology and reducing the number of required design variables relative to homogenization-based approaches. Resulting designs are fabricated with selective laser sintering technology, and their geometric and elastic properties are evaluated experimentally. / text

Additive Manufacturing (AM) processes which include Selective Laser Sintering (SLS) have experienced tremendous growth and development since their introduction over 20 years ago. It becomes highly important at this stage to evaluate the sustainability of the process and refine it to reduce energy and material consumption. In this study, a sustainability analysis was performed on the SLS process with Nylon-12 using the Environmental and Resource Management Data (ERMD) known as Eco-Indicators. The energy perspective alone was considered and a Total Energy Indicator (TEI) value was calculated using various parameters to quantify process sustainability: process productivity, energy consumption rate, etc. Precise thermal control of selective laser sintering (SLS) is desirable for improving geometric accuracy, mechanical properties, and surface finish of parts produced. An experimental setup to monitor the temperature distribution was designed using Resistance Temperature Detectors (RTD) as a part of this study. Discrepancies in temperature profiles were investigated and recommendations were made to improve thermal characteristics of the SLS process. / text

Selective laser sintering (SLS) is a commercial, powder-based manufacturing process that produces parts with complicated shape and geometry based on a computer solid model. One of the major drawbacks of SLSed inter-metallic and ceramic parts is their high porosity because of the use of binder system. High porosity results in poor mechanical, electrical and thermal properties of the preform and hence renders it unsuitable for various applications. This thesis attempts to infiltrate SLSed preforms by carrying out electrochemical deposition of metal ions inside the interconnected pore network. One of the major benefits of carrying out this novel process is low processing temperature as opposed to existing methods such as melt infiltration. Low temperature reduces both energy consumption and associated carbon-footprint and also minimizes undesirable structural changes. Both conductive and non-conductive preforms may be electrochemically infiltrated, and MMCs produced by this method have potential for use in structural applications. / text

Modernios pienininkystės fermos sėkmė priklauso nuo to, ar joje gaminamas pienas yra aukštos kokybės. Pagrindiniai veiksniai, turintys įtakos somatinių ląstelių skaičiui piene, yra gera melžimo organizacija, melžimo įrangos taisyklingas veikimas, klinikinių mastitų gydymas antibiotikais ir kt. Mokslininkai įrodė, kad melžti karves kas dvylika valandų yra optimaliausia, kai jos melžiamos du kartus per parą. SLS piene daug priklauso nuo taisyklingos melžimo darbotvarkės, kuri apima skirtingas melžimo operacijas (tešmens ir spenių paruošimas melžimui, spenių dirginimas, pirmųjų pieno čiurkšlių numelžimas, melžiklių užmovimas ant spenių, melžiklių numovimas pamelžus ir efektyvi spenių antiseptika po melžimo) ir nuo šių operacijų trukmės. Teisingai atliekamos melžimo procedūros yra svarbios mastito prevencijai ir užtikrina visišką pieno išmelžimą iš tešmens. Tyrėjai įrodė, kad daugiau kaip 50 % melžimo proceso laiko užtrunka pats melžimas. Dabartiniu metu melžimo operacijos vis labiau mechanizuojamos. Netaisyklingas melžimas gali pailginti pieno atleidimo laiką, didėja rizika susirgti tešmens uždegimais. Pablogėja pieno kokybė, todėl gaunami ekonominiai nuostoliai. Padidėjęs somatinių ląstelių skaičius piene ¬ svarbus mastito požymis. Perdirbamajai pramonei karvių mastitas buvo ir liks vienu iš svarbiausių trukdžių gaminant aukštos kokybės pieno produktus. Klinikine forma serga 2 – 5 % laktuojančių ir užtrūkintų karvių, o slaptuoju uždegimu – iki 50 % karvių. Viena dažniausiai... [toliau žr. visą tekstą] / Data were collected from two dairy farms. On the farm A cows were milked using full automatised milking equipment „Milkmaster“. On the farm B cows were milked with „Interpuls“ milking equipment. The DeLaval milking system was supplied with automatic cluster remover. On dairy farms A and B cows were milked twice daily. The goal of our studies was to analyse consumption of main milking operations (cow udder preparation before milking, milking and over-milking) and their influence on milk somatic cell count. Were selected 20 cows in each farm. The duration of main milking procedures were recorded. Data on milk, fat and protein yields and somatic cell count were collected.The mean duration of pre-milking udder preparation was 42 s (farm A) and 46,03 s (farm B). Some cows were prepared only for 25,50 Afarm A) s, whereas the udder preparation comprised merely inadequate cleaning of teats. The maximum duration of over-milking was 41,10 (farm B).

Mūsų tyrimų duomenimis analizuotoje fermoje yra pakankamai aukštas išmilžis, kuris už 2007 metus sudarė 6234 kg per laktaciją. Karvių bandoje per mažą procentą sudaro pimaveršės (11,3%). Vyresnės karvės bandoje pasiskirsto beveik vienodai : antraveršės – 24,7 %, trečiaveršės- 39,1 % ir ketvirtos laktacijos- 24,7 %. Karvių sergamumas slaptuoju mastitu priklauso nuo produktyvumo. Mūsų tyrimai rodo, karvės, kurių produkcija per laktaciją buvo 3000 kg pieno - iki 200 tūkst./ml somatinių ląstelių turėjo 20,93 %, 3001 – 5000 kg – 55,8 % ir virš 5001 kg – 23,26 % karvių. Antroje bandomoje grupėje, karvių somatinių ląstelių skaičius buvo 201 – 400 tūkst./ml pirmaveršių buvo 20,0 %, 3001 – 5000 kg- 43,3% ir virš 5001 kg – 36,6 %. Trečioje bandomojoje grupėje ( 24 karvės) 401 tūkst./ml SLS turėjo 25 %, 3001 – 5000 kg – 16,7% ir virš 5001 kg – 58,3 %. Tyrimai rodo, kad didėjant karvių produktyvumui jos dažniau serga slaptuoju mastitu. Tuo mūsų tyrimų duomenys sutampa su J. Rudejevienės (2007), E Aniulio (2007), Sederevičiaus (2004) tyrimų duomenimis. Analizuojant pažeistus karvių tešmens ketvirčius pastebėjome, kad vienas ketvirtis buvo pažeistas pas 40,0 %, du ketvirčiai - 30 %, trys ketvirčiai - 16,7 % ir visi ketvirčiai 13,3 %. Šio tyrimo duomenys nevisiškai sutampa su J. Klimaitės (2005) duomenimis. Manome, kad pažeistų ketvirčių skaičius priklauso nuo karvių laikymo būdo, sanitarinių ir kitų priežasčių. Pieno sanitarinė būklė priklauso nuo tvarto higienos, spenių paruošimo melžimui... [toliau žr. visą tekstą] / According to the data of our studies, there is quite high milk yield in analyzed farm. This milk yield composed 6234 kg per lactation during 2007. In the herd of cows there is a small percent of first-calf cows (11,3%). Older cows are spread in the herd almost equally: second- calf cows – 24,7 %, third-calf cows- 39,1 %, and cows of fourth lactation- 24,7 %. Cows’ morbidity with subclinical mastitis depends on productivity. Our study shows that cows whose production during lactation was 3000 kg- till 200 thousands/ml of somatic cells had 20,93 %, 3001 – 5000 kg – 55,8 % and over 5001 kg – 23,26 % of cows. In the second experimental group the somatic cells count 201 – 400 thousands/ml had 20,0 % of first-calf cows, 3001 – 5000 kg- 43,3% and over 5001 kg – 36,6 %. In the third experimental group ( 24 cows) 401 thousands/ml of SCC (somatic cells count) had 25 %, 3001 – 5000 kg – 16,7% and over 5001 kg – 58,3 %. Studies show that during the rise of productivity of cows they more often suffer from subclinical mastitis. According to this aspect our studies data are compatible with research data of J. Rudejevienė (2007), E Aniulis (2007), Sederevičius (2004). While analysing damaged udder quarters we noticed that one quarter was damaged at 40,0 %, two quarters - 30 %, three quarters - 16,7 % and all four quarters- 13,3 %. The data of this study are only partially compatible with data of J. Klimaitė (2005). It is clear that the number of damaged quarters depends on the way of cows’... [to full text]