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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Mass Transfer Phenomena in Rotating Corrugated Photocatalytic Reactors

Xiang, Yuanyuan 18 December 2013 (has links)
Photocatalysis is a green technology that has been widely used in wastewater treatment. In this work, mass transfer processes in corrugated photocatalytic reactors were characterized both experimentally and through computer simulations. For the experimental work, various drum rotational speeds, reactor liquid volumes and number of corrugations were studied to elucidate their effects on mass transfer phenomena. The mass transfer rate was found to increase with increasing rotational speed. Liquid volumes in the reactor significantly affect the mass transfer rate when 20% of the surface area of the drum was immersed. A higher mass transfer rate was found using the drum with 28 corrugations, which had the lowest mass transfer coefficient when compared to the drums with 13 and 16 corrugations. In the computer simulations, velocity and concentration fields within the corrugated reactors were modelled to explore the characteristics of mass transfer processes. The mass transfer coefficients predicted by the simulations were lower than those measured experimentally due to mass transfer limitations occurring between the corrugation volume and bulk solution in the simulations. Based on mass transfer characteristics, it was determined that the drum with 28 corrugations was the most efficient photocatalytic reactor, and had the lowest mass transfer coefficient among those studied.
12

Analysis of rib-plate response to external loading

Zhao, Jia-Xiang. January 1989 (has links)
Thesis (M.S.)--Ohio University, March, 1989. / Title from PDF t.p.
13

Field and laboratory characterization of corrosion potential in highway corrugated metal pipe

Crowder, Andrew January 1900 (has links)
Master of Science / Department of Civil Engineering / Stacey E. Kulesza / Thousands of metallic drainage structures have been installed by the Kansas Department of Transportation (KDOT) to facilitate proper drainage of highway systems across the state. Several studies were conducted over the past 30 years by KDOT to determine the durability of different corrugated metal pipe (CMP) materials and estimate their performance against the deterioration that occurs due to the electrochemical process of corrosion. These past studies have influenced KDOT policy regarding pipe material, but a method to quickly determine the rate of deterioration, and accurately predict a service life, is still not well defined. With the last comprehensive study performed in 1990 by KDOT, there is now a need to perform a field evaluation to determine the performance of CMPs in Kansas. This research conducted a survey of observed CMP conditions for 80 sites across KDOT districts one and four using a quantitative observational rating system. The goal of the survey was to determine the performance of CMPs in the field. The findings of this study indicate that a 1975 change in KDOT pipe policy has increased the rapid deterioration of CMPs. An additional study was conducted to determine if accurate service life predictions could be made based on chemical and biological characteristics of soil taken near the CMP invert. A method to test the leachate water exposed to the soil sample was created. Laboratory results of four field samples indicated that the rate at which the invert deteriorated corresponded to the total amount of chloride anion mobilized in the leachate over a 72-hour period, along with the standard deviation of pH measured throughout the test. This contradicts most field corrosion tests that only measure field pH and resistivity. The developed method of measuring soil sample leachate may provide a more accurate estimate of the performance of CMP in the sample location.
14

Mass Transfer Phenomena in Rotating Corrugated Photocatalytic Reactors

Xiang, Yuanyuan January 2014 (has links)
Photocatalysis is a green technology that has been widely used in wastewater treatment. In this work, mass transfer processes in corrugated photocatalytic reactors were characterized both experimentally and through computer simulations. For the experimental work, various drum rotational speeds, reactor liquid volumes and number of corrugations were studied to elucidate their effects on mass transfer phenomena. The mass transfer rate was found to increase with increasing rotational speed. Liquid volumes in the reactor significantly affect the mass transfer rate when 20% of the surface area of the drum was immersed. A higher mass transfer rate was found using the drum with 28 corrugations, which had the lowest mass transfer coefficient when compared to the drums with 13 and 16 corrugations. In the computer simulations, velocity and concentration fields within the corrugated reactors were modelled to explore the characteristics of mass transfer processes. The mass transfer coefficients predicted by the simulations were lower than those measured experimentally due to mass transfer limitations occurring between the corrugation volume and bulk solution in the simulations. Based on mass transfer characteristics, it was determined that the drum with 28 corrugations was the most efficient photocatalytic reactor, and had the lowest mass transfer coefficient among those studied.
15

Effect of Pallet Deckboard Stiffness and Unit Load Factors on Corrugated Box Compression Strength

Baker, Matthew W. 29 March 2016 (has links)
Corrugated paper boxes are the predominant packaging and shipping material and account for the majority of packaging refuse by weight. Wooden pallets are equally predominant in shipping, transportation and warehousing logistics. The interaction between these two components is complex and unexplored leaving industry to compensate with outdated component specific safety factors. Providing a focused exploration of the box and pallet interaction will open the door for holistic design practices that will reduce cost, weight, damage, and safety incidents. This study was separated into four chapters exploring different aspects of the corrugated box to pallet interaction. The first chapter evaluates the support surface provided by a pallet consists of deckboards spaced perpendicular to the length of the pallet. The resulting gaps between deckboards reduce the support to the box. Gaps were limited to 55% of box sidewall length for practical reasons. The effect of gaps was significant and produced a nonlinear reduction in box strength. Small boxes were more susceptible to gaps than larger boxes. Moving the gap closer to the corner increased its effect while increasing the number of gaps did not increase the effect. A modification to the McKee equation was produced that was capable of predicting the loss in strength due to gaps. The equation is novel in that is modifies a widely used equation and is the first such equation capable of handling multiple box sizes. This study also has practical implications for packaging designers who must contend with pallet gap. Chapter 2 explores the relationship between deckboard deflection and box compression strength. Testing found that reducing the stiffness of the deckboard decreases the compression strength of the box by 26.4%. The location of the box relative to the stringer also had varying effects on the box strength. A combination of deckboard stiffness and gaps produced mixed with results with gaps reducing the effect of stiffness. It was observed that lower stiffness deckboards not only deflect but also twist during compression. The torsion is suspected to have a significant influence on compression but further exploration is needed. The third chapter tests the effect of box flap length on box compression strength under various support conditions. Variables included four flap lengths, gaps between deckboards, low stiffness deckboards, column stacking and misaligned stacking. The results show that the box flaps can be reduced by 25% with no significant effect of box strength under any support condition tested. Furthermore, the box flap can be reduced by 50% with less than 10% loss in compression strength under all scenarios. These results have significant sustainability implication as 25% and 50% reduction in box flap reduce material usage by approximately 12% and 24%, respectively. In the fourth and final chapter, the theory of beam-on-elastic foundation is applied to deckboard bending and corrugated boxes. In this model the corrugated box acts and the foundation and the deckboard is the beam. Rotational stiffness, load bridging, and foundation stiffness changes required the development of novel testing solution and model development. The model was capable of predicting the distribution of force along the length sidewall but was not capable of predicting the ultimate strength of the box. The model developed in the study will be applicable in determining potential weakness in the unit load in addition to optimizing those that are over designed. These four chapters represent a considerable contribution of applicable research to a field that relied on outdated safety factors over thirty years. These safety factors often lead to costly over design in an industry where corrugated box and pallets volumes make event the smallest improvements highly beneficial. Furthermore, this research has opened the door for significant additional research that will undoubtedly provided even greater economic and sustainability benefits. / Ph. D.
16

The Effect of the Stiffness of Unit Load Components on Pallet Deflection and Box Compression Strength

Phanthanousy, Samantha 08 June 2017 (has links)
Currently, pallets are designed assuming that the load is distributed evenly on the top of the pallet. When pallets are loaded with packages such as corrugated boxes or returnable plastic containers, due to their physical shape, packages, are not capable of deforming freely with the pallet and a bridging phenomenon occurs. During this load bridging phenomenon, a portion of the vertical forces are redistributed as horizontal forces which causes the redistribution of the vertical compression stresses on the pallet towards the support. As a result, the deflection of the pallet can decrease and the load capacity of the pallet can increase significantly. The second chapter of this paper investigates the effect of package content on pallet deflection. The study concluded that package content did not have a significant effect on pallet deflection within the boundary conditions of the experiment. The third part of this paper considers how a specific pallet characteristic could affect the way a corrugated box performs. Standard box design procedures include adjustments of estimated compression strength for relative humidity, overhang on pallets, vibration, and alignment of boxes. However, there is no adjustment factor for pallet stiffness. The objective of the study described in this thesis is to find an answer for how the compression strength of a box is affected by pallet stiffness and top deckboard twist. The study concluded that the pallet stiffness and top deckboard twist do not have an effect on the compression strength of the box until less than 12% of the area box is supported. / Master of Science
17

Investigation into load bridging effect for block class pallets as a function of package size and pallet stiffness

Morrissette, Steven Michael 08 July 2019 (has links)
Pallets and corrugated boxes are ubiquitous in the global supply chain. However, the interactions that exist between the boxes and pallet are ignored during the pallet design process resulting in an over design of pallet performance and the waste of raw materials. The goal of this research is to understand how pallet performance is affected by headspace, box size, and base design across multiple support conditions using block class wooden pallets. Headspace and base design had no effect on pallet deflection for the experimental weights used throughout testing. The effect of box size was significant on pallet deflection across multiple support conditions. The effect was greatest for lower stiffness pallets and low stiffness support conditions (RAW) with up to a 50% reduction in pallet deflection observed by switching from small to large boxes on a very low stiffness pallet. Evaluation of pressure mat data showed an increase in the redistribution of pressure away from the center of the pallet and towards the supports as box size increased. The redistribution of pressure towards the supports is known as load bridging and validates the observed reduction in pallet deflection as a function of box size. The results indicate that incorporating the effect of packages into current pallet design practices could result more effective and cheaper pallet designs. / Master of Science / Transportation and storage of material goods at a national and international level is an integral part of our economy with pallets and corrugated boxes making up the majority of packaging materials. Currently, the interactions that exist between the boxes and pallet are ignored during pallet design resulting in an over design of pallet performance and a waste of raw materials. Understanding the interactions that exist in a unit load is important in optimizing pallet performance, reducing the amount of raw materials used, and ultimately reducing cost. This research project is specifically focused on the interactions between corrugated boxes and block class wooden pallets. The effect of headspace (the gap between the products and the top of the box) and box size was investigated as a function of pallet stiffness, support condition, and bottom deck design. Both pallet deflection and the pressure distribution on the top surface of the pallet were examined to evaluate pallet performance. It was found that headspace does not have an effect on pallet deflection unless the weight of the unit load exceeds 3,500 lbs. for small boxes and 1,750 lbs. for large boxes. Base design showed no significant effect on pallet deflection for all of the support conditions evaluated. The effect of box size had a major effect on the deflection of the pallet. Large boxes showed the greatest change especially when lower stiffness pallets were used. Increasing the box size can reduce the deflection of the pallet as much as 50% which means that pallets supporting larger boxes could support much more weight than currently estimated. Evaluation of pressure mat data showed that when the size of the boxes increased, more pressure is distributed towards the supports. More pressure is applied to the pallet section on the top of the supports; therefore, less pressure is available to cause pallet bending. This finding validates the observed reduction in pallet deflection as a function of box size. The obtained results help pallet designers to incorporate the interactions between the packages and the pallet into their design process which will allow them to reduce the amount material used for pallet.
18

Lateral Torsional Buckling Strength of Sinusoidal Corrugated Web Plate Girders

Reinders, Philip January 2022 (has links)
Corrugated web plate girders (CWPGs) have become an increasingly popular structural member in Canada in recent years. This is because of their economic efficiency over standard wide flange members. Although the flexural performance of such has been increasingly studied in recent years there is still advancements that can be made in their design. No research has been completed in Canada on the subject of lateral torsional buckling (LTB) strength and very minimal research has been published on sinusoidal CWPGs. In order to examine the LTB strength of a CWPG with a sinusoidally shaped web, nine specimens were loaded and failed in simply supported arrangement that favours lateral torsional buckling. Specimens were chosen to observe the difference in strength due to web thickness, web depth and variation in identical beams. All of the specimens recorded strengths that exceeded the theoretical design strengths confirming that the current design procedure is conservative. A trend of ultimate capacity increasing was observed with the increase of web thickness. The depth of the web had no significant effect on the torsional strength besides what is gained from the increased flange distance. An equivalent web thickness equation was formulated based on the results for the purpose of calculating LTB strength. To test the proposed equation a numerical analysis was run on a wider range of beams and compared with the testing results. It was determined the physical testing results can be effectively captured by the proposed equation among more than just the tested beams. Two additional analyses were prepared to lay the foundation for further investigation of the proposed equation. The first was a Monte Carlo simulation to test the risk of using the proposed equation which requires additional data. Secondly, a preliminary finite element analysis (FEA) model was developed and presented for future use to expand this research. / Thesis / Master of Applied Science (MASc) / Corrugated web plate girders (CWPG) have grown in popularity due to their economic efficiency. No research has been presented in Canada and very minimal research has been published on the lateral torsional strength of CWPGs with sinusoidally corrugated webs. This research studied the lateral torsional buckling (LTB) strength of CWPGs through the experimental testing of physical members and a new equation for the calculation of the LTB strength is proposed. This equation and design process was then numerically tested to determine its viability as a design process.
19

Experimental and Analytical Evaluation of an Innovative Strengthening System for Long-Span Deep-Corrugated Buried Bridges

Gomes, Nevil 15 June 2017 (has links)
No description available.
20

Experimental and numerical analysis of the dynamic load distribution in a corrugated packaging system

Jamialahmadi, Arsalan January 2008 (has links)
<p>It is well known that transportation means high and varying loads for products as well as packages. To develop corrugated boxes with optimal design and efficient use of raw materials is crucial. Vibrations and shocks acting on pallets during transportation are transferred to the corrugated boxes and considerably reduce the integrity and life time of the boxes. The development of experimental and analytical tools for measurement and prediction of the influence of dynamic loads on the box performance, such as stacking strength and conservation of stacking pattern would therefore be of large practical importance. In order to develop such tools, it is important to know the load distribution between different boxes. This master thesis presents a technique for investigating these stresses based on a pressure sensitive film, which gives many data points. A series of tests using random and sinusoidal vibration testing have been done utilising this technique and results are presented for different positions on the pallet and for different box filling methods. Investigations performed on the vibrations of the boxes also demonstrate a pitch type of motion. A level-crossing study on the forces existing between the boxes shows a Rayleigh force distribution. A mathematical model is also proposed for simulation of a stacking system. Advantages and disadvantages with this technique and with the model are described. Comparison between the experimental and numerical results shows a proper correlation. Using the pressure sensitive film as a quantitative sensor and applying the recorded data for the statistical study of the contact forces existing in a stack of boxes gives useful and important results for further analysis of the fatigue life and vulnerable positions of boxes.</p><p> </p>

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