No description available.

The objectives of this project were:<br />1.����To compare the drying cost and drying time for oak and poplar pallets for the following mold mitigation strategies for hardwood pallets: air drying, forced air drying (fan shed), kiln drying to 25% moisture content and chemical treatment, and<br />2.����Develop and evaluate a procedure for preventing and controlling mold growth on heat treated hardwood pallets<br />Twenty red oak pallets and twenty yellow-poplar pallets were tested for each drying method to compare costs and to determine drying times. �Additional pallets were obtained to conduct a more thorough air drying procedure. �Drying data was extrapolated to allow estimates of the drying time from green (83% moisture content for poplar and 64% moisture content for oak) to 25%. �<br />After the pallets reached the desired 25% moisture content, they were placed in a 40�" enclosed trailer, inoculated with mold (Aspergillus, Stachybotrys, and Penicillium) and were left undisturbed for a period of 14 days. �After the 14 day incubation period, the pallets were inspected for mold using the ASTM D-4445 Standard Test Method for Fungicides for Controlling Sapstain and Mold on Unseasoned Lumber. �<br />A comparison of drying costs was then conducted to determine which method was the most cost efficient based on the data obtained in this study. �The cost to treat the pallets with each treatment was calculated including electrical cost, labor, and tax values. �In addition to the cost comparison, a Net Present Value (NPV) was calculated to determine which method produced the best outcome over a longer period of time.<br />Two heat treatment and drying schedules were then developed to meet both IPPC-ISPM #15 requirements and achieve the desired 25% moisture content with minimal degrade. �This was accomplished by testing several HT/drying schedules on green yellow-poplar and white oak pallets until the pallets met the criteria for being heat treated and had minimal degrade. �The schedules developed are a modified oak HT/KD schedule that required 30 hours to complete and a modified poplar HT/KD schedule that required 16 hours to complete.<br />The results demonstrated that that mold would not grow on the pallets stored in an enclosed container when the dew point is not reached. Air-drying pallets, chemical application in conjunction with air-drying pallets, fan shed drying pallets and kiln drying pallets to a 19-24% moisture content was demonstrated to prevent mold growth on oak and yellow poplar pallets. Estimates for the time required to dry yellow-poplar and oak pallets to 19% and 25% moisture content were developed for air-drying, forced air-drying and kiln drying for the conditions experienced in Blacksburg, VA between 7/30/2008 and 11/10/2008. Air-drying pallets was found to have the lowest daily operational cost but not the lowest total drying cost. �Fan shed drying had the lowest drying cost to achieve 25% moisture content. �Kiln drying was the most expensive daily and total cost, but yielded the fastest method of drying pallets to 25% moisture content. A NPV cost comparison showed that over a 3 year (36 month) time period, fan shed drying is the most cost effective method of drying pallets based on the values used in this study. Given the environmental conditions experienced between 7/30/2008 and 11/10/2008, no mold grew on the air-dried, fan shed, and kiln dried pallets during the drying process. <br /> / Master of Science

In the past decade, a fundamental research topic in the information systems (IS) discipline has been to examine the value of online platforms on businesses, society, and consumers, notably in the form of improved efficiency in information sharing, consumer engagement, and increased sales. However, the risks rooted in online platforms may cannibalize the value created, which have received limited attention in the literature and practice. In my dissertation, I attempt to fill this gap in the literature by providing a comprehensive analysis of the risks of online platforms from the angle of these three main entities in the ecosystem with three separate yet related essays. The first essay focuses on the risks for businesses that leverage social media platforms, and assesses how their posting on social media fan pages affects consumers’ decision to purchase and unfollow from the firms. The second essay focuses on the risks of fake news on social media and how social media platforms may use identity verification to reduce online anonymity and combat this increasingly critical social problem. The third essay focuses on estimating the risks of using monetary incentives to motivate consumers to write online product reviews, and examines how such strategy may affect product sales. Our studies have theoretical and practical implications for designing effective online platform information systems. / Business Administration/Management Information Systems

The effects of trailing edge flow control on the wakes of a linear cascade of idealized fan blades was investigated experiments with a view to the likely effects on broadband aircraft engine interaction noise. Single and three-component hotwire velocity measurements were made downstream of the cascade for a chord Reynolds number of 390,000 and a Mach number of 0.07. Measurements of the two-point velocity correlation were used extensively to evaluate the impact of various flow control strategies on the organization of the coherent structures of the wakes and their potential to generate noise. A baseline flow was established by measuring the wake downstream of unmodified GE-Rotor-B blades. Four sets of serrated trailing edge blades (with two different serration sizes and with two trailing edge cambers) and three sets of blades with trailing edge blowing (a simple rectangular slot, rectangular slot with Kuethe-vane vortex generators, and rectangular slot with serrated lips) were tested. The serrated trailing edges introduce corrugations into the wake, increase the wake decay and width as well as turbulence levels (possibly because of the blunt trailing edge created at the serration valley). The serrated trailing edges also increase the turbulence scales in the direction perpendicular to the plane of the wake because of the injection of streamwise vorticity. In almost all cases the serrations reduce the spanwise and streamwise turbulence scales. Serrations do not, however, affect the apparent time scale of quasi-periodic structures in the wake, and this appears to limit the potential of this trailing edge treatment to reduce broadband noise. The analysis of the characteristic eddies (obtained from proper orthogonal decomposition combined with linear estimation) revealed that the serrations do not change the qualitative form of the eddies. Trailing edge blowing was found to significantly decrease the wake deficit and width as well as the turbulence levels at all blowing rates. Blowing through the simple rectangular slot, at mass flow rates between 1.4 and 2.0% of the total passage through flow, was shown to significantly affect the size, the organization and the strength of the coherent structures. For small blowing rates the strong spanwise eddies near the trailing edge actually appear to be enhanced. For larger blowing rates, however, the turbulent scales are reduced in all directions. The addition of Kuethe vanes on the suction side of the blowing blade results in a low momentum region just downstream of the vanes that may result from flow separation there. This further enhances the shedding and increases the blowing rate needed to overcome it. The serrated blowing blades show the greatest potential to reduce broadband noise as they reduce the turbulence levels and scales without creating potentially detrimental structures. While no acoustic measurements were made, analysis of hypothetical perpendicular and parallel interactions of blades with these wakes has made possible to characterize for the first time the impact of the changes in the eddy structure of these wakes on their potential to generate broadband noise. The serrated trailing edges (especially the larger serrations) actually increase the potential of the wake to generate broadband noise (a direct consequence in the overall increase in turbulence scale and intensity). In contrast, every trailing edge blowing configuration was found to produce large reductions in the potential noise (a maximum of 6dB reduction was obtained at 2.0% blowing). The addition of Kuethe vanes on the suction side of the blowing blades significantly reduced the efficiency of the simple blowing configuration (a result of the increased coherency associated with the shedding of streamwise vorticity by the vanes). The serrated blowing configuration was found to yield reductions similar to the simple blowing configuration. / Ph. D.

A series of experiments were conducted in a F109 turbofan engine to investigate the unsteady wake profiles of an Inlet Guide Vane (IGV) at a typical spacing to the downstream fan at subsonic and transonic relative blade velocities. The sharp trailing-edge vanes were designed to produce a wake profile consistent with modern IGV. Time averaged baseline measurements were first performed with the IGV located upstream of the aerodynamic influence of the fan. Unsteady experiments were performed with an IGV-fan spacing of 0.43 fan chords. High-frequency on-vane pressure measurements showed strong peak-to-peak amplitudes at the blade passing frequency (BPF) of 4.7 psi at the transonic fan speeds. High-frequency total pressure measurements of the IGV wake were taken between the IGV and fan. Results showed that the total pressure loss coefficient of the time averaged IGV wake is reduced by 30% for the subsonic fan, and increased by a factor of 2 for the transonic fan compared to the baseline. Time resolved wake profiles for subsonic fan speeds show constructive and destructive interactions over each blade pass generated by the fan potential flow field. Time resolved wake profiles for the transonic fan speeds show that shock interactions with the IGV surface result in the wake shedding off of the vane at the BPF. Furthermore, the effectiveness of trailing edge blowing (TEB) flow control was investigated. TEB is the method of injecting air aft of the IGV to reduce the low pressure regions (deficits) in the viscous wakes shed by the vanes. Minimizing the IGV wakes reduces the forcing function on the downstream fan blades, thereby reducing high cycle fatigue. The TE span of the vane contains discrete holes at the axial centerline for TEB. Baseline results showed that TEB eliminates the IGV wake, while using only 0.03% of the total engine mass flow per IGV. TEB for the subsonic fan at the close spacing shows complete wake filling using the same mass flow as the baseline. TEB for the transonic fan shows a reduction of 68% in the total pressure loss coefficient, while requiring 2.5 times the mass flow as the baseline. / Ph. D.

The use of induction fans for face ventilation in room and pillar mines has proved to be an efficient, flexible, and viable technique. In addition to their merits over conventional systems, induction fans enable remote controlled mine operations with low maintenance requirements. Theoretical investigations were conducted initially to verify the potential of free air jets in mine ventilation. A laboratory model using water as the fluid medium was designed to study the flow characteristics of a jet fan in a blind entry. The model was tested in a variety of brattice curtain and nozzle combinations to investigate the ventilating efficiency of jet fans. A jet fan was selected and tested in a full scale model and in a coal mine. Experiments were conducted to evaluate the laboratory flow models. Flow quantities and velocities in the entry were measured using state-of-the-art instrumentation to quantify various parameters. Air velocities near the face were found to be satisfactory to dilute contaminants from the face. A model for the axial velocity profile of the jet was suggested. Beyond 25m distance from the jet fan exit the jet tended to move away from the wall to the opposite wall. Carbon dioxide was used as a tracer gas to measure the effective ventilating air quantity near the face and re-circulation in various tests. The re-circulation involved in the system was found to be less than 40% in all the experiments. It was also found that the use of line curtains in combination with a jet a fan can eliminate any type of re-circulation. Numerical modeling of a jet fan in a typical coal mine heading was conducted to obtain details of the flow. The results of the simulation using computational fluid dynamics were similar to the flow patterns observed in the experiments. It was found that a jet fan can effectively ventilate an entry as deep as 40m. Fan positioning, airway geometry, airway surface properties, and mine layout severely affect its performance. It is therefore necessary to understand the flow mechanics of a jet fan in a mine heading before applying the technique for a particular situation. / Ph. D.

In most man-made flight, vehicle control is achieved by deflecting flaps. However, in nature, morphing surfaces are found on both flying and swimming creatures. Morphing is used in nature because it is a more efficient form of control. This thesis investigates using morphing flaps to control a class of UAVs known as ducted fan vehicles. Specifically, this thesis discusses both the challenges and benefits of using morphing control surfaces. To achieve morphing, a piezoelectric device known as Macro Fiber Composites is used. These devices are embedded in the skin of the vehicles control surface, and when actuated, they cause the control surface to increase or decrease camber. This thesis describes experiments that were performed to investigate the performance of this type of actuator. Specifically, the actuation bandwidth of these devices is presented and compared to a servo. Results show that the morphing control surfaces can actuate at frequencies twice as high as a servo. / Master of Science

<p dir="ltr">Despite the associated time, cost, and effort, experimental fan research remains necessary to validate computational models and physically develop new technologies. The need for a new fan research facility that would provide high quality experimental fan research at engine-representative speeds using detailed flow measurements was identified by the Office of Naval Research (ONR). The facility would be used to develop stall margin enhancement techniques, namely casing treatments to advance the field. In addition to support by ONR, Honeywell Aerospace donated a transonic fan rig and core exhaust plenum to make this project a reality.</p><p dir="ltr">The new research facility was designed and built around this new fan rig for investigations into casing treatments, inlet distortion, and aeromechanics research, as well as future projects that would make use of the new space. The funding package included a renovation of the build room in ZL1 and two brand new test cells constructed in previously empty space. All necessary equipment was designed, procured, and placed in the correct positions to ensure operability of the fan. The new space necessitated a mechanical checkout and commissioning process before conducting research projects.</p><p dir="ltr">In parallel to the development of the facility, a novel fan casing was designed to make use of rapid prototyping to experimentally test casing treatments. The fan casing assembly is made up of three metal components that remained fixed and six individual 3D printed plastic inserts that make up the flowpath surrounding the rotor. The geometry of each component was developed according to best-practices and computational structural analysis. Following commissioning of the fan test cell, the new fan casing was successfully implemented and tested over the full operating range of the fan.</p>

The purpose of this thesis is to establish whether Swedish fan conventions organised around East-Asian popular culture such as anime and manga can be identified as a form of secular ritual. The methods used to determine this include participant observation, interviews and ethnographic data. Defining secular ritual as a performance event that establishes an alternative context that transforms the everyday without being connected to a religious or supernatural worldview or origin, we find that Swedish conventions of this kind may be called a form of ritual that engages people united by a common, broad field of interests and a notion of being outside of society’s norms in different ways, most notably in regards to sexuality and gender. This opens a discussion about Swedish fan conventions and how they may inform us about the use and function of rituals in a secularised society.

本研究是為了比較電視媒體和網路社交媒體在名人與粉絲間的類社會互動程度與後續情感及行為效果上是否有差異。藉由蒐集314份網路問卷，以類社會互動程度為自變項、情感效果與行為效果為應變項，分別比較這兩種媒體。研究結果顯示：第一、不同媒介在引發粉絲對名人的類社會互動上的確存在差異，且以電視的影響力較大。第二、在類社會互動程度引發的情感、行為反應方面，電視都顯著地高於網路社群。第三、整體來說類社會互動程度在預測網路社群上的情感、行為反應是有效的預測變數，與過去電視媒體的文獻結果一致。此外，本研究也發展出粉絲類型量表，以量化的方式將粉絲依照對名人的感興趣程度分成低、中、高三類。進一步將三類粉絲分開檢視，發現粉絲類型確實會調節類社會互動程度與情感、行為效果。 / This research was done to study the relationship between the level of fans’ parasocial interaction and the effects caused by television and online social media. This study collected 314 online questionnaires. The independent variable was the level of parasocial interaction and the dependent variables were affective effects and behavioral effects, including the importance of celebrities, emotions of celebrities’ disappearance, activity, and adaption.The findings of this study indicate that television produced significantly greater influence on the level of parasocial interaction toward celebrities than online social media.Furthermore, the affective effects and behavioral effects caused by parasocial interaction from TV are more significant than the result from social media. Generally speaking, the level of parasocial interaction effectively predicts fans’ affective and behavioral in the context of online social media, which is consistent with the result found in the past television studies. Besides, this study developed a fan scale to classify fans into three levels, including low-interest fans, moderate-interest fans, and high-interest fans. The result reveals that the level of fans can moderate the effects of the level of parasocial interaction, affective effects, and behavioral effects of television and online social media.