Minskad tillgång på fossila material och ökade energibehov i värden skapar ett behov av att utveckla alternativa och miljömässigt hållbara lösningar. Biobränsle har därför växt till en av de viktigaste förnyelsebara energikällorna i målet mot ett koldioxidneutralt samhälle. Dock skapar det obearbetade biobränslet problem, på grund av den höga fuktkvoten, mellan 50-150 %. Som en följd finns ett torkbehov som måste lösas på ett miljö- och energieffektivt sätt. Idag står torkningen av biomaterial innan pelletering för 25 % av den totala kostnaden vid pelletstillverkning. Kostnaden för att torka biomaterialet gör det viktigt att effektivisera torkningen, samtidigt bidrar torkningen till utsläpp av miljöfarliga ämnen såsom terpener. Torkningen måste dessutom ske med jämn kvalitet, så att biomaterialet håller konstant och homogen fukthalt för att möjliggöra effektiv processering. Beroende på vad biomaterialet skall användas till krävs olika torkhalter. Ideal fuktkvot för förbränning är till exempel 15-25 %, medan för pyrolys skall fuktkvoten helst ligga mellan 5-10 % för en effektiv och högkvalitativ process. För pellets skall fuktkvoten idealt ligga mellan de två nämnda processerna, nämligen 8-12 %. Tre vanliga torkartyper för torkning av biomaterial är roterande torktrumma, bandtork och pneumatisk tork. I detta arbete bestäms tryckfallet i en pneumatisk tork. Pneumatisk tork fungerar genom att ett luftflöde transporterar och torkar ett vått material. Fördelarna med en pneumatisk tork är den korta torkningstiden, samtidigt som materialet får en jämn fuktkvot. Den korta torktiden bidrar dessutom med att utsläpp av lättflyktiga organiska föreningar (VOC) såsom terpener är små jämfört med de andra två nämnda torkarna, samt att brandrisken är låg. Kostnaden för pneumatisk torkning är dock högre på grund av det höga gasflödet som krävs jämfört med materialflödet, samt svårigheter med att effektivt separera det torkade materialet från luftflödet. Det skapades en modell som predikterade tryckfallet i en pneumatisk tork, och verifiera det simulerade tryckfallet mot ett praktiskt uppmätt tryckfall på en pneumatisk torkanläggning. På detta sätt skapades en modell som kan undersöka olika material- och luftflöden, och hur de påverkar tryckfallet. Arbetet ger förslag på hur tryckfall och hastigheter kan beräknas dels i regionen för accelerationen av materialflödet, vid stationärt flöde samt i U-böjar. För att anpassas till det praktiskt uppmätta tryckfallet användes därefter ett korrigeringssamband som skapades genom observationer från en kalibrerande körning för den pneumatiska torkanläggningen. Resultaten av modellen stämmer överens med forskning inom pneumatisk transport och torkning. Modellen gav med hjälp av korrigeringssambandet ett mycket bra resultat över hur tryckförlusterna varierar över sträckan i en pneumatisk transport. Tryckfallet var som väntat större för högre material- eller luftflöden. Då sågspånet accelererade till sin maxhastighet på en sträcka mellan 0,4-0,6 meter, beroende på luftflödets hastighet, krävs fler mätpunkter i regionen mellan 0-0,6 meter för att bättre kunna konstatera exakt hur tryckfallet under spånets acceleration sker. Skillnaden mellan det praktiskt uppmätta och det simulerade tryckfallet var aldrig mer än 7,0 % för de flöden som undersökts i detta arbete. Då man bortsåg från mätpunkten vid 0,4 meter var skillnaden mellan uppmätt och simulerat tryckfall aldrig mer än 4,4 %. Om värmeöverföringen mellan materialet och luften tas med i modellen, kan den användas för att prediktera energiåtgång och behövd längd för att uppnå önskad fuktkvot på materialet. / The reduced availability of fossil fuels and the increasing energy demand in the world creates a need to develop solutions that are financial and environment sustainable. Biofuels has grown to become one of the most important renewable energy sources in the target towards a carbon neutral society. Although the high moisture content ranging between 50-150% for unprocessed biofuels causes problems. As a result, there is a drying demand that has to be solved in an energy efficient and environmental friendly way. As of today, the drying of biomaterials pre pelletizing stands for 25 % of the total cost in pellets production. The cost to dry biomaterials makes it important to improve the efficiency of the drying process. Simultaneously the drying process causes emissions of hazardous substances such as terpenes. The drying must also in a consistent quality so that the biomaterial is made to hold constant and uniform moisture content to enable efficient processing. Depending on the usage of the biomaterial, there is a different demand of the final moisture content before processing. The ideal moisture content for combustion for example ranges between 15-25 %, while pyrolysis would rather have moisture content between 5-10 % for effective and high quality processing. The ideal moisture content pre pelletizing is between the two mentioned processes, namely 8-12 %. Three common dryers used to dry biomaterials are rotary dryers, conveyor dryer and pneumatic dryer. In this thesis the pressure drop in a pneumatic dryer is predicted. A pneumatic dryer a airflow simultaneously conveys and dries the wet material. Perks of a pneumatic dryer is the short amount of time required to dry the material, and simultaneously deliver uniform moisture content. The short time required also contributes to minimize the emissions of volatile organic compounds (VOC) like terpenes compared to the other two mentioned types of dryers and the risk of fire during the drying process. Although because of the high airflow compared to the material flow, pneumatic drying is costly and has difficulties with separating the dried material from the airflow. A model to predict the pressure drop in a pneumatic dryer was created. The simulated pressure drop was then verified against a practically measured pressure drop for a pneumatic dryer. In this way a model was created to examine the pressure drop for a variety of material- and airflows. The thesis suggests how to calculate the pressure drop and velocities for the accelerating region, steady state and U-bend of pneumatic conveying. To better predict the pressure drop according to the actually measured pressure drop a correction equation was presented. The results of the model are consistent with the research in pneumatic conveying and drying. The model gave with the usage of the correction equation a very good prediction on how the pressure drop varied over the length of the pneumatic conveying. The pressure drop was as expected larger as the airflow or material flow increased. As the sawdust accelerated on 0,4-0,6 meters there is required more points of measurements in the region between 0-0,6 meters to better establish exactly how the pressure drop in the accelerating region varies. The difference between the practically measured and the simulated pressure drop was never exceeded 7,0 % for the different flows investigated in this thesis. When disregarding the measure point at 0,4 meters the difference between measured and simulated pressure drop never exceeded 4,4 %. If one would include the heat transfer between the material- and airflow, the model could be used to predict the energy consumption and required length to achieve desired moisture content on the material.

Physical exercise is a trend that continues to grow, especially at the gym, but there are still members that do not use their training card in full. The overall aim of this study was therefore to investigate infrequent member’s experience of their training card. To answer this, focus was on motives to card purchase and perceived opportunities and difficulties of using the training card. The data was collected at IKSU trough a group interview with four managers within the organization, a questionnaire replied by 39 infrequent members and of those 11 individual interviews. The results showed that the motives differed between the informants but the main was the physical health. The three factors that were identified as affecting were frame-, facility- and personal factors. The conclusions drawn was that training facilities can develop procedures to capture their infrequent members in three areas; the occasion for the card purchase, customized training card and follow-up.

<p>Surface energy-powered motion is useful for a variety of autonomous functions such as passive cooling and self-cleaning, where independence from external forces is highly desirable. Drop coalescence offers a convenient process to release surface energy, which can be harvested to power self-propelled fluid motion. </p><p>On superhydrophobic surfaces, out-of-plane jumping motion spontaneously results from drop coalescence. However, less than 4\% of the released surface energy is converted to useful kinetic energy giving rise to the jumping motion. Using three-dimensional interfacial flow simulations that are experimentally validated, we elucidate the mechanism of low energy conversion efficiency. The non-wetting substrate interferes with the expanding liquid bridge between the coalescing drops at a relatively late stage, forcing a small fraction of the merged drop to "bounce" back from the non-wetting substrate. The substrate breaks the symmetry of surface energy release, leading to self-propelled jumping that is perpendicular to the solid substrate. The intercepting substrate imparts a relatively small translational momentum on the overall merged drop, giving rise to a small energy conversion efficiency. </p><p>This mechanistic understanding has provided guidance on how to increase the energy conversion efficiency by changing the geometry of the intercepting solid surface, e.g. to a pillared substrate which has additional intercepting planes, or to a cylindrical fiber which interferes with the coalescence process at a much earlier stage. These topographical changes have already led to a 10-fold increase in energy conversion efficiency. The directional control of surface energy-powered motion is achieved by breaking the symmetry of oscillations induced by drop coalescence, such as by adding additional intercepting planes on pillared substrates. The work has applications ranging from self-sustained dropwise condensers, drop coalescers to ballistospore discharge in some fungi species in nature. </p><p> The ballistospore discharge process is powered by surface energy released from the coalescence between a spherical Buller's drop and an adaxial drop on the spore. The disturbance to the adaxial drop from coalescing Buller's drop results in the capillary-inertial oscillations of the liquid system. The oscillations redirect the mass and momentum transfer and yields a tensile force along the adaxial direction with negligible momentums in other directions, ensuring the preferable launching along the adaxial direction. The findings offer insights for applications of biomimicry involving self-propelled jumping with payloads which takes advantage of the high power density of the process.</p> / Dissertation

Slamming of marine planing craft is expected to arise due to the high speed nature of their operating conditions. High hydrodynamic forces are inevitably induced causing the shell plating to deflect, which in turn can influence the flow physics surrounding the hull. In order to study the hull’s hydroelastic response due to a slamming event, wedge drop experiments were performed with an aluminum wedge of 57 inches in length, 47 inches in breadth, and 20 degree deadrise with 1/4 in. thick unstiffened bottom panels. The elastic behavior of the hull plating was measured via two methods. The first method uses strain gages to analyze the wedge’s deadrise panel deflections, and the second method is a Stereoscopic- Digital Image Correlation (S-DIC) technique. In the present investigation, an S-DIC code has been developed and utilized to study the deflections and to advance the capabilities of future research. Comparisons are made between the methods and also with theoretical studies. The deflections measured are approximately 0.1 in. on a panel spanning 24.5 inches, and the predictions made using S-DIC and strain gages differ by approximately 23%.

With the current trend of CO2 mitigation in process industries, the primary goal of this thesis is to promote biomass as an energy and reduction agent source to substitute fossil sources in the steel industry. The criteria for this substitution are that the steel process retains the same function and the integrated energy efficiency is as high as possible. This work focuses on advanced gasification of biomass and waste for substitution of fossil fuels in steel industry heat treatment furnaces. To achieve this, two approaches are included in this work. The first investigates the gasification performance of pretreated biomass and waste experimentally using thermogravimetric analysis (TGA) and a pilot plant gasifier. The second assesses the integration of the advanced gasification system with a steel heat treatment furnace. First, the pyrolysis and char gasification characteristics of several pretreated biomass and waste types (unpretreated biomass, steam-exploded biomass, and hydrothermal carbonized biomass) were analyzed with TGA. The important aspects of pyrolysis and char gasification of pretreated biomass were identified. Then, with the objective of studying the gasification performance of pretreated biomass, unpretreated biomass pellets (gray pellets), steam-exploded biomass pellets (black pellets), and two types of hydrothermal carbonized biomass pellets (spent grain biocoal and horse manure biocoal) were gasified in a fixed bed updraft gasifier with high-temperature air/steam as the gasifying agent. The gasification performance was analyzed in terms of syngas composition, lower heating value (LHV), gas yield, cold gas efficiency (CGE), tar content and composition, and particle content and size distribution. Moreover, the effects on the reactions occurring in the gasifier were identified with the aid of temperature profiles and gas ratios. Further, the interaction between fuel residence time in the bed (bed height), conversion, conversion rate/specific gasification rate, and superficial velocity (hearth load) was revealed. Due to the effect of bed height on the gasification performance, the bed pressure drop is an important parameter related to the operation of a fixed bed gasifier. Considering the limited studies on this relationship, an available pressure drop prediction correlation for turbulent flow in a bed with cylindrical pellets was extended to a gasifier bed with shrinking cylindrical pellets under any flow condition. Moreover, simplified graphical representations based on the developed correlation, which could be used as an effective guide for selecting a suitable pellet size and designing a grate, were introduced. Then, with the identified positive effects of pretreated biomass on the gasification performance, the possibility of fuel switching in a steel industry heat treatment furnace was evaluated by effective integration with a multi-stage gasification system. The performance was evaluated in terms of gasifier system efficiency, furnace efficiency, and overall system efficiency with various heat integration options. The heat integration performance was identified based on pinch analysis. Finally, the efficiency of the co-production of bio-coke and bio-H2 was analyzed to increase the added value of the whole process. It was found that 1) the steam gasification of pretreated biomass is more beneficial in terms of the energy value of the syngas, 2) diluting the gasifying agent and/or lowering the agent temperature compensates for the ash slagging problem in biocoal gasification, 3) the furnace efficiency can be improved by switching the fuel from natural gas (NG) to syngas, 4) the gasifier system efficiency can be improved by recovering the furnace flue gas heat for the pretreatment, and 5) the co-production of bio-coke and bio-H2 significantly improves the system efficiency. / <p>QC 20160825</p>

The purpose of this study was to determine if significant differences existed in attitudes of international students concerning college withdrawal. Data collection involved 200 freshmen international students from two universities in Texas. Two questionnaires were distributed to the students to determine attitudes toward college withdrawal. The instrument used to score the attitudes was the Purdue Master Attitude Scale. The analysis of variance was used for the statistical evaluation. The statistics indicated there was no significant differences between the students tested in the study and that the students had favorable attitudes toward college and unfavorable attitudes toward college withdrawal. Based on the findings of this study, universities should devise an extensive counseling and orientation program in order to provide students opportunities to complete their college education.

Thermal analysis is an important topic that can affect the electrical machine performance, reliability, lifetime and efficiency. In order to predict the electrical machine thermal performance accurately, thermal analysis of electrical machines must include fluid flow modelling. One of the technologies which may be used to estimate the flow distribution and pressure losses in throughflow ventilated machines is flow network analysis, but suitable correlations that can be used to estimate the pressure losses in rotor ducts due to fluid shock is not available. The aim of this work is to investigate how the rotation affects the pressure losses in rotor ducts by performing a dimensional analysis. Apart from the additional friction loss due to the effects of rotation, other rotational pressure losses that appear in a rotor-stator system are: duct entrance loss due to fluid shock and combining flow loss at the exit of the rotor-stator gap. These losses are analysed using computational fluid dynamics (CFD) methods. The CFD simulations use the Reynolds-averaged Navier Stokes (RANS) approach. An experimental test rig is built to validate the CFD findings. The investigation showed that the CFD results are consistent with the experimental results and the rotational pressure losses correlate well with the rotation ratio (a dimensionless parameter). It shows that the rotational pressure loss generally increases with the increase in the rotation ratio. At certain operating conditions, the rotational pressure loss can contribute over 50 % of the total system loss. The investigation leads to an original set of correlations for the pressure losses in air ducts in the rotor due to fluid shock which are more suitable to be applied to fluid flow modelling of throughflow ventilated machines. Such correlations provide a significant contribution to the field of thermal modelling of electrical machines. They are incorporated into the air flow modelling tool that has been programmed in Portunus by the present author. The modelling tool can be integrated with the existing thermal modelling method, lumped-parameter thermal network (LPTN) to form a complete analytical thermal-fluid modelling method.

CONTACT ANGLE OF A NANO-DROP ON A HETEROGENEOUS SURFACE By John Andre Ritchie, Master of Science A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at Virginia Commonwealth University Virginia Commonwealth University, 2010 Major Director: Dr. Alenka Luzar, Professor of Chemistry We examine the relation between contact angle of a nanodrop of water and the location of surface-water interaction energy at the perimeter and beneath the drop. Young’s equations gives the relationship between surface tension, at the three phase solid liquid vapor interface, and contact angle on a homogeneous surface. Cassie and Baxter generalized this equation to heterogeneous surfaces implying that contact angle corresponds to the average properties of the surface under the drop. McCarthy and coworkers pointed out it is the nature of the substrate at droplet perimeter that controls contact angle. And more recently, McHale in his theoretical derivation applies the Cassie-Baxter equation to the area at the drop’s perimeter. For a nanodrop, the situation is further complicated by the finite range of water-substrate interactions making the definition of the perimeter region somewhat arbitrary. We simulate nanodroplets of water on graphene-like surfaces having hydrophobic and hydrophilic interaction energy at the perimeter and beneath the drop using molecular dynamics. The microscopic analogue of the contact angle was extracted from simulation trajectory data. We confirm the contact angle is exclusively related to the surface interaction energy in the region of the drop’s perimeter. We test the role of finite range of substrate-water interaction when the area of a circular hydrophilic patch beneath the drop’s core is incrementally expanded until the contact angle is equivalent to that on the pure hydrophilic surface. We identify a range of interaction corresponding to a considerable drop in θ when plotting contact angle as a function of patch size. We show the observed contact angle dependence on the size of the patch can be predicted by the Cassie-Baxter mixing relation when limited to the area within the interaction range from the drop’s perimeter.

Löpning är en av de största fysiska aktiviteterna runt om i världen. Det räknas med att 37-56 % av alla som löper någon gång drabbas av en skada i samband med löpningen. Studiens syfte är att undersöka effekten av olika dämpningsmaterial, drop samt motion-kontroll av löparskor på skadefrekvens i samband med pronation och supination under löpning. Studien gjordes som en litteraturstudie där 11 vetenskapliga artiklar ingick i studien. Resultatet visar att motion-kontroll skor rekommenderas till pronerande löpare och neutrala skor till supinerande eller neutrala löpare. Minskat drop leder till minskad skaderisk. Framfotslöpning är att föredra jämfört med häl till tå löpning. En mjuk sula är bättre vid kortdistans och en hårdare sula vid långdistans. EVA material visade på en bättre återhämtningseffekt än TPU.

Reverse-flow combustors have been used in heavy land-based gas turbines for many decades. A sheath is typically installed to provide cooling at an expense of large pressure losses, through small jet impingement cooling and strong forced convention channel flow. With the modern advancement in metallurgy and thermal-barrier coating technologies, it may become possible to remove this sheath to recover the pressure losses without melting the combustor chamber. However, without the sheath, the flow inside the dump diffuser may exert nonuniform cooling on the combustion chamber. Therefore, the objective of this project is to investigate the flow pattern, pressure drop, and heat transfer in the dump-diffuser reverse-flow combustor with and without sheath to determine if the sheath could be removed. The investigation was conducted through both experimental and computational simulation. The results show that 3.3% pressure losses could be recovered and the highest wall temperature will increase 18% without the sheath.