Dissertations / Theses on the topic 'Compression effect'
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1
Alkharabsheh, Khaled S. "Image compression and its effect on data." Huntington, WV : [Marshall University Libraries], 2004. http://www.marshall.edu/etd/descript.asp?ref=462.
2
Gan, Khong Wui. "Effect of high through-thickness compression on composite failure." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616885.
Abstract:
As composite materials are now used in load conditions with increasing complexity and thickness, all the three-dimensional stress components become important and should be taken into account when predicting failures. In particular, the through-thickness stresses can play a crucial role in determining the in-plane behaviours and strength of a composite, laminate. The work presented in this PhD thesis aims to investigate failures due to complex stress fields at the root of a composite component in a dovetail assembly, where highly concentrated through-thickness stresses as well as in-plane tensile and interlaminar shear stresses are present. The problem was decoupled into two simpler multiaxial load cases which were studied separately: (1) through-thickness compression with interlaminar shear, and (2) through-thickness compression with longitudinal tension. They were investigated experimentally using new loading configuration in a biaxial test machine. This bridges the gap in reliable multiaxial experimental data which is lacking in the open literature. This was then combined with a finite element (FE) modelling approach to, develop simple failure criteria which are validated for engineering design purposes. A simple constitutive law which takes into account the effect of transverse compression and analytical tools which can be I easily utilised to predict stresses and failures in composites were also developed. The findings of this thesis were finally applied to a severely tapered dovetail composite specimen, together with some mitigation strategies, to predict its ultimate fibre failure load and the failure locations.
3
Ragan, Paula Marie. "The effect of mechanical compression on chondrocyte gene expression." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85347.
Abstract:
Thesis (Ph.D.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 1999.Includes bibliographical references (leaves 115-122).
by Paula M. Ragan.
Ph.D.
4
Talal, Sina. "Effect of long-term compression on rigid polymer foams." Thesis, Kingston University, 1999. http://eprints.kingston.ac.uk/20640/.
Abstract:
The sponsors of this project have been using the rigid heavily-crosslinked polyurethane foam detailed in this study for load-bearing applications. One of the main requirements of this material is that it must possess excellent recovery properties following extensive compressive periods over several years. For such long loading regimes, there is need for detailed understanding of the compressive behaviour of this material, and its subsequent recovery upon release. More recently, there has been a growing interest in replacing the polyurethane foam with an alternative cellular plastic that possesses similar, if not identical, compressive recovery and behaviour. Attention was focused on the other primary polymer contingent, a polyethylene foam. A polyimide foam was also considered as it was already being used in applications similar to those of the polyurethane foam. The structures of the foams were investigated by means of Differential Scanning Calorimetry, Scanning Electron Microscopy and Image Analysis. The deformation mechanisms that occur during the application of a compressive force were examined visually via a scanning electron microscope compression rig. The mechanical analysis involved stress-strain testing whereby three stages of compression were identified (‘linear elastic, stress plateau and densification’), as described in the literature. Quadratic relationships were found to exist between the foam density and the ‘elastic modulus, plateau modulus and the compressive strength’ respectively. Such relationships had previously been found to exist in the literature, but not for the rigid variety of foam at such a broad range of densities. Further analysis included a detailed study of the recovery of the polyurethane (100 kg m[sup]-3 to 800 kg m[sup]-3) foams, a lightly-crosslinked polyethylene foam and a non-crosslinked polyimide foam. The foam samples were compressed by strains which spanned their linear elastic and stress plateau regimes i.e. by 2.5% to 35% for periods ranging from 3 days up to one year at ambient temperature. This analysis was also undertaken at elevated temperature as a means of accelerating the ageing process. Recovery of all of the samples was monitored for a minimum of 100 days at ambient temperature following release. Recovery of all of the foams tested was found to occur in two stages; an initial rapid recovery within the first day following release followed by a much slower recovery phase over a period of approximately 100 days. The initial rapid recovery was attributed to the recovery of the bulk polymer whilst the recovery of the cellular structure was associated with the ensuing slower recovery phase. In addition, recovery of the foams was found to be dependent more upon the compressive strain than on other parameters, such as compressive period and foam density. For compressive periods exceeding two weeks, recovery is almost independent of the latter parameters.
5
Thorp, George. "The Effect of Compression Recovery Pants on Cycling Performance." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1430470588.
6
Comstedt, Erik. "Effect of additional compression features on h.264 surveillance video." Thesis, Mittuniversitetet, Avdelningen för informationssystem och -teknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-30901.
Abstract:
In video surveillance business, a recurring topic of discussion is quality versus data usage. A higher quality allows for more details to be captured at the cost of a higher bit rate, and for cameras monitoring events 24 hours a day, limiting data usage can quickly become a factor to consider. The purpose of this thesis has been to apply additional compression features to a h.264 video steam, and evaluate their effects on the videos overall quality. Using a surveillance camera, recordings of video streams were obtained. These recordings had constant GOP and frame rates. By breaking down one of these videos to an image sequence, it was possible to encode the image sequence into video streams with variable GOP/FPS using the software Ffmpeg. Additionally a user test was performed on these video streams, following the DSCQS standard from the ITU-R recom- mendation. The participants had to subjectively determine the quality of video streams. The results from the these tests showed that the participants did not no- tice any considerable difference in quality between the normal videos and the videos with variable GOP/FPS. Based of these results, the thesis has shown that that additional compression features can be applied to h.264 surveillance streams, without having a substantial effect on the video streams overall quality.
7
Waizmann, Tabea. "The effect of compression and expansion on stochastic reaction networks." Thesis, IMT Alti Studi Lucca, 2021. http://e-theses.imtlucca.it/335/1/Waizmann_phdthesis.pdf.
Abstract:
Markov chains are a fundamental model to study systems
with stochastic behavior. However, their state space is often
of an unmanageable size, making the use of approximations
and simplifications necessary for analytic solutions. This thesis
considers reaction networks as a well-known representation
for Markov chains describing interactions between species
populations. It presents several methods using model transformations
to aid with the effective analysis of such systems.
Species equivalence is a reduction technique that lifts the concept
(and related algorithms) of Markov chain lumpability
from lumping of states to directly lumping species in a reaction
network. This allows the simplification of a reaction
network without first examining its state space.
The tool DiffLQN implements a method for the analysis of
large-scale stochastic models for the performance evaluation
of software systems using an approach based on deterministic
rate equations, by means of a compact system of ordinary
differential equations that approximate only mean estimates
for stochastic reaction networks.
Deterministic rate equations are generally accurate for networks
with large populations, but may incur errors when elements
are only present in low copy numbers. This thesis
presents finite state expansion, which aims to solve that problem.
It does so by converting a given reaction network into
an expanded one with additional species and reactions such
that the overall stochastic behavior is preserved. The resulting
rate equations, however, may enjoy increased accuracy.
Several tests on example models show that finite state expansion
proves competitive with other state-of-the-art methods.
8
Ndebele, Nothando Elizabeth. "Clustering algorithms and their effect on edge preservation in image compression." Thesis, Rhodes University, 2009. http://hdl.handle.net/10962/d1008210.
Abstract:
Image compression aims to reduce the amount of data that is stored or transmitted for images. One technique that may be used to this end is vector quantization. Vectors may be used to represent images. Vector quantization reduces the number of vectors required for an image by representing a cluster of similar vectors by one typical vector that is part of a set of vectors referred to as the code book. For compression, for each image vector, only the closest codebook vector is stored or transmitted. For reconstruction, the image vectors are again replaced by the the closest codebook vectors. Hence vector quantization is a lossy compression technique and the quality of the reconstructed image depends strongly on the quality of the codebook. The design of the codebook is therefore an important part of the process. In this thesis we examine three clustering algorithms which can be used for codebook design in image compression: c-means (CM), fuzzy c-means (FCM) and learning vector quantization (LVQ). We give a description of these algorithms and their application to codebook design. Edges are an important part of the visual information contained in an image. It is essential therefore to use codebooks which allow an accurate representation of the edges. One of the shortcomings of using vector quantization is poor edge representation. We therefore carry out experiments using these algorithms to compare their edge preserving qualities. We also investigate the combination of these algorithms with classified vector quantization (CVQ) and the replication method (RM). Both these methods have been suggested as methods for improving edge representation. We use a cross validation approach to estimate the mean squared error to measure the performance of each of the algorithms and the edge preserving methods. The results reflect that the edges are less accurately represented than the non - edge areas when using CM, FCM and LVQ. The advantage of using CVQ is that the time taken for code book design is reduced particularly for CM and FCM. RM is found to be effective where the codebook is trained using a set that has larger proportions of edges than the test set.
9
Shi, Lu-Feng. "Effect of dynamic compression characteristics on aided perception of reverberant speech." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.
10
McDonald, G. J. "Optical sampling and metrology using a soliton-effect compression pulse source." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19219/.
Abstract:
A low jitter optical pulse source for applications including optical sampling and optical metrology was modelled and then experimentally implemented using photonic components. Dispersion and non-linear fibre effects were utilised to compress a periodic optical waveform to generate pulses of the order of 10 picoseconds duration, via soliton-effect compression. Attractive features of this pulse source include electronically tuneable repetition rates greater than 1.5 GHz, ultra-short pulse duration (10-15 ps), and low timing jitter as measured by both harmonic analysis and single-sideband (SSB) phase noise measurements. The experimental implementation of the modelled compression scheme is discussed, including the successful removal of stimulated Brillouin scattering (SBS) through linewidth broadening by injection dithering or phase modulation. Timing jitter analysis identifies many unwanted artefacts generated by the SBS suppression methods, hence an experimental arrangement is devised (and was subsequently patented) which ensures that there are no phase modulation spikes present on the SSB phase noise spectrum over the offset range of interest for optical sampling applications, 10Hz-Nyquist. It is believed that this is the first detailed timing jitter study of a soliton-effect compression scheme. The soliton-effect compression pulses are then used to perform what is believed to be the first demonstration of optical sampling using this type of pulse source. The pulse source was also optimised for use in a novel optical metrology (range finding) system, which is being developed and patented under European Space Agency funding as an enabling technology for formation flying satellite missions. This new approach to optical metrology, known as Scanning Interferometric Pulse Overlap Detection (SIPOD), is based on scanning the optical pulse repetition rate to find the specific frequencies which allow the return pulses from the outlying satellite, i.e. the measurement arm, to overlap exactly with a reference pulse set on the hub satellite. By superimposing a low frequency phase modulation onto the optical pulse train, it is possible to detect the pulse overlap condition using conventional heterodyne detection. By rapidly scanning the pulse repetition rate to find two frequencies which provide the overlapping pulse condition, high precision optical pulses can be used to provide high resolution unambiguous range information, using only relatively simple electronic detection circuitry. SIPOD’s maximum longitudinal range measurement is limited only by the coherence length of the laser, which can be many tens of kilometres. Range measurements have been made to better than 10 microns resolution over extended duration trial periods, at measurement update rates of up to 470 Hz. This system is currently scheduled to fly on ESA’s PROBA-3 mission in 2012 to measure the intersatellite spacing for a two satellite coronagraph instrument. In summary, this thesis is believed to present three novel areas of research: the first detailed jitter characterisation of a soliton-effect compression source, the first optical sampling using such a compression source, and a novel optical metrology range finding system, known as SIPOD, which utilises the tuneable repetition rate and highly stable nature of the compression source pulses.
11
Sabrina, Irene. "Effect of the Manual Ischemic Compression on the Biological Movement Kinematic." Thesis, Högskolan Dalarna, Institutionen för information och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:du-38053.
Abstract:
The purpose of this research is to the investigate the effectiveness of the Local Ischemic Compressiontreatment given to the patients who suffered from a cerebrovascular event, and present themusculoskeletal disorders characterized by the presence of trigger points, specifically regardingelliptical motor performance.There exist studies that demonstrate the kinematic characteristics of linear and elliptical movement inpeople with trigger points without neurological injury, however, these characteristics have not beendescribed in patients who have suffered a cerebrovascular event. Thus, this study is novel whenanalyzing the improper motor functioning in non-paretic upper limb movement control. These typesof patients have been approached from the perspective of neurological injury, and the musculoskeletalinjury that could have an impact on movement control has been neglected.This study provides new evidence on the motor performance of the non-paretic upper limb in peoplewho are suffering from musculoskeletal pain. The obtained results helped us to understand the motorfunctioning in the study sample and offers new insights based on the kinematic characteristics andpower law analysis of the movement performed.Analysis being carried out by considering the 2/3 power law, an empirical law which helps in studyingthe relationship between the tangential hand speed and the curvature of its trajectory during curvedmotion, is widely acknowledged to be an invariant of upper-limb movement. Therefore, the study isfocused on this law to interpret the effectiveness of the Local Ischemic Compression treatment givento the patients suffering with musculoskeletal injury resulting myofascial trigger points. The obtainedresults shows that power law is not much altered by the treatment which means that the ischemiccompression has only a peripherical effect (i.e., musculoskeletal system) and does not affect the motorprogramme of the human being (i.e., central nervous system). The one possible reason of having suchresults could be small sample size. Further research is suggested with large study sample.
12
Lu, Tran Diem T. (Trinh). "The effect of auditors’ workload pressure and compression on audit quality." Master's thesis, University of Oulu, 2016. http://urn.fi/URN:NBN:fi:oulu-201605121710.
Abstract:
This study aims to examine the effect of workload compression and workload pressure on overall audit quality. It is motivated by the little available evidence concerning this potential effect as well as author’s experiences in audit profession. Workload pressure and workload compression are surrogated by busy season (i.e fiscal year end date in December), audit workload (i.e pressure degree of audit company on clients’ portfolio at certain point of time), audit concentration (i.e concentration of audit company on one client at certain point of time). Abnormal accrual is the proxy of audit quality. The main purpose of the study is to strengthen the results of prior research by López & Peters (2012), then requires management team of audit firms draw more attentions on preparing resources to ensure audit quality for all ongoing engagements. In other words, it requires audit partners become more prudent before accepting new clients, moreover, new regulations about the resource preparation should be issued to ensure the audit quality. Our study used a sample of 6,500 observations between 2010 and 2013 from Compustat and Audit Analytics.
The results show that busy season companies have higher abnormal accruals, in other words, workload compression and workload pressure negatively affect audit quality, which is consistent with prior researches. Moreover, our study found the company size and number of business segments, geographical segments and operating segments also affect audit quality. This result is an open topic for further researches in the future because of its inconsistency with previous study.
13
Bateman, Simon David. "The effect of speed of compression on the properties of compacts." Thesis, Liverpool John Moores University, 1988. http://researchonline.ljmu.ac.uk/4892/.
Abstract:
A high speed hydraulic press has been developed into a computer controlled high speed compression Simulator, capable of reproducing displacement time profiles seen on any production tabletting machine. The system has been validated to monitor punch displacements to ?12pm and loads to ?O.05% of full scale. Confidence in the results obtained using the Simulator were enhanced by comparison with other operational Simulators. The established Simulator was then used to investigate the effects of compression on ibuprofen. Ibuprofen was found to consolidate mainly by plastic deformation with a lesser contribution from the melting of asperities. A significant amount of pressure induced melting and subsequent fusion bonding occurred at higher pressures. Ibuprofen was found to be sensitive to the magnitude and rate of application of the compression pressure. The extent of plastic flow exhibited by ibuprofen during compression was, found to decrease as the compression speed increased. Lamination and capping of ibuprofen compacts at high compression speeds was considered to be due to a combination of air entrapment and the inability of the compact to withstand the stresses of decompression. When ibuprofen was mixed with a second material and compressed, the consolidation mechanism and properties of the compacts formed were found to follow complex relationships. The relationships were dependant on the proportion of each material and the speed of compression. For ibuprofen microcrystalline cellulose mixtures positive interactions were considered to occur due to bonding between the two materials. For ibuprofen and lactose mixtures the interactions observed were considered to be a balance between the plastic deformation by the ibuprofen relieving the applied load preventing the cri tical force required for fracture of the lactose being attained, and the lactose fragments bearing the applied load reducing plastic flow by ibuprofen. The Simulator was then employed to investigate different aspects of tabletting machine design. A simple ibuprofen microcrystalline cellulose mixture and a commercial ibuprofen formulation were compressed to a constant load and then to a constant thickness and the properties of the compacts compared. Tablets prepared under a constant maximum applied load, with fill weights varied over the B.P uniformity of weight limits, had relatively constant disintegration times and radial tensile strengths. This was considered an advantage over the tablets prepared to a constant thickness which showed considerable varia?tion under the same conditions. The second aspect of tabletting machine design to be investigated was the use of relatively high precompression pressures using a commercially available paracetamol granulation. The maximum compression pressure exerted during the tableting cycle was found to be the major factor contributing to the tensile strength of the tablets. The use of a second compression either before or after the main compression was found to produce a significant increase in tablet tensile strength. The greater the magnitude of the second compression, the greater its effect on tensile strength. The contribution of a second compression towards the tablet tensile strength was attributed to the effective increase in dwell time it generated. The orientation of the greater and lesser compression pressures during tableting was found to influence the tablet tensile strength. Stronger tablets resulted if the greater pressure was exerted first. This was considered to be a function of temperature increases within the tablet and the disruptive effects of the second compression.
14
Mango, Omar I. K. "The effect of design parameters of compressors on the performance of domestic refrigerators." Thesis, University of Hertfordshire, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259540.
15
Sun, Zuwen. "Effect of Photoacoustic Radar Chirp Parameters on Profilometric Information." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37116.
Abstract:
Photoacoustic imaging for biomedical application has attracted much research in recent years. To date, most of the work has focused on pulsed photoacoustics. Recent developments have seen the implementation of a radar pulse compression methodology into continuous wave photoacoustic modality, however very little theory has been developed in support of this approach. In this thesis, the one-dimensional theory of radar photoacousticsfor pulse compressedlinear frequency modulated continuous sinusoidal laserphotoacoustics is developed.The effect of the chirp parameters on the corresponding photoacoustic signal is investigated, and guidelines for choosing the chirp parametersfor absorber profilometric detectionare given based on the developed theory and simulations. Simulated results are also compared to available experimental results and show a good agreement.
16
Nakano, Tamon. "Étude numérique de l’interaction choc/couche limite en géométrie de révolution." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2018. http://www.theses.fr/2018ESMA0013/document.
Abstract:
Les phénomènes d’interactions choc/couche limite sont dimensionnants pour de nombreuses applications des domaines de l’aéronautique et du spatial. Ils peuvent être associés à la formation de décollements instationnaires à basse fréquence qui n’ont été étudiés jusqu’à présent qu’en géométrie plane. La présente étude vise à caractériser ce type d’interaction en configuration cylindrique. Un outil de simulation numérique directe,basé sur l’extension de schémas hybrides aux différences finies de haute précision (centrés optimisés6/WENO 5) en géométrie curviligne, a été développé et validé à travers divers cas test standards. Une première partie de l’étude se focalise sur l’influence d’un effet de courbure transverse sur le développement des propriétés d’une couche limite supersonique à Mach 3. Il est montré que l’augmentation de la courbure relative de la couche limite tend à réduire l’énergie de fluctuation à basse fréquence près de la paroi, tout en renforçant les perturbations à hautes fréquences dans la zone externe de la couche limite. En comparaison avec le cas plan, la courbure transverse induit une ré-organisation notable des structures de la couche limite et un comportement différent des invariants d’anisotropie des contraintes, mais ne conduit qu’à une légère modification des distributions de contraintes et de l’équilibre global d’énergie cinétique turbulente. Une seconde partie de l’étude se concentre sur la zone d’interaction avec une rampe de compression et le mouvement instationnaire du choc en géométrie de révolution complète. La déformation azimutale du choc est caractérisée dans son mouvement. Elle apparaît essentiellement associée à la fluctuation de la ligne de décollement et l’organisation des structures tourbillonnaires amont. Il est montré que l’énergie des modes azimutaux de pression pariétale fluctuante est plus amplifiée pour les modes d’ordre plus élevé. La contribution à l’effort latéral associé au mode 1 apparaît plus particulièrement marquée à basses fréquences dans la zone amont au point de décollement et à moyennes fréquences en aval de la zone de recollement sur la rampe où les niveaux les plus élevés de fluctuations sont observés. Il est montré que les fluctuations à basses fréquences sont en revanche portées par des modes azimutaux d’ordre de plus en plus élevé à travers la zone d’interactionShock wave/boundary layer interactions (SWBLI) are present in various aerospace engineering applications.They can be associated with separated regions yielding low-frequency unsteadiness, which have mainly been studied in planar geometries. The present study aims at characterizing this type of interaction in a cylindrical configuration. A direct numerical simulation solver has been developed and validated with various test cases. It is based on a high-order finite difference based hybrid schemes (6th order centered scheme/5thorder WENO), extended to curvilinear geometries. Transverse curvature effects on properties of spatially developing supersonic boundary layer at Mach 3 are first examined. It is shown that the increase of the relative curvature of the boundary layer tends to reduce the fluctuation energy at lower frequencies near the wall, while reinforcing the perturbations at higher frequencies in the upper zone of the boundary layer.In comparison with the planar case, the transverse curvature leads to a significant re-organization of the boundary layer structures and a subsequent modified behavior of the invariants of anisotropy turbulent stress tensor. It however only leads to slightly modified distributions of Reynolds stress and a rather similar overall balance of turbulent kinetic energy through the boundary layer. The second part of this study is dedicated to the unsteady motions of the shock/separation zone in a cylinder/compression flare configuration for which the full cylindrical geometry is taken into account. The shock distortions in the azimutal direction appears to be mainly associated to the organization of the upstream vortex structures and the subsequent azimutal fluctuations of the separation line. It is shown that the energy of the fluctuating wall pressure is more amplified for higher order azimutal modes. The contributions to lateral forces, associated to the first mode, are dominated by low-frequencies only upstream of the separation line in the intermittent region. They become more dominant in the middle frequency range downstream of the reattachment zone on the ramp. It is also shown that the low-frequency activity at the wall is progressively due to higher order azimuthal modes through the interaction zone
17
Van, Heyningen Martha Catharina. "Investigating the effect of compression on the permeability of fibrous porous media." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86245.
Abstract:
Thesis (MSc)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Fluid flow through porous media plays an important role in a variety of contexts of which filtration is one. Filtration efficiency of fibrous filters depends on the micro-structural characterization of these porous materials and is reflected in the permeability there-of. Compression of fibrous porous media has a significant effect on the permeability. Experimental data indicate that the permeability varies generally with more than an order of magnitude over the narrow porosity range in which the compression takes place. Relative to the amount of experimental studies regarding this phenomenon, there is a scarcity of geometric models in the literature that can account for the effect of compression on the permeability of a fibrous porous medium. Within the context of existing geometric porescale models based on rectangular geometry, a new model is presented and an existing model improved to predict the effect of one-dimensional compression in the streamwise direction. In addition, without compromising on a commitment to mathematical simplicity, empirical data of a non-woven fibrous porous medium was used to highlight the effect of model geometry on its predictive capability. Different mathematical expressions for the relationship between compression and porosity were considered. The permeability is expressed explicitly in terms of the fibre diameter and the compression fraction and implicitly in terms of the porosity. The porosity is incorporated through the relationship between the linear dimensions of the geometric model. The general applicability of the model(s) was validated by making use of data on airflow through a soft fibrous porous material as well as through glass and nylon fibres. The permeability predictions fall within the same order of magnitude as the experimental data. Given the mathematical simplicity of the model(s), the prediction capability is satisfactory. Attention is drawn to assumptions made and model restrictions within the analytical modelling procedure. A general predictive equation is presented for the permeability prediction in which a solid distribution factor is introduced. The proposed models serve as basis for further adaptation and refinement towards prediction capability.
AFRIKAANSE OPSOMMING: Vloei van vloeistowwe deur poreuse media speel ’n belangrike rol in ’n verskeidenheid kontekste waarvan filtrasie een is. Die filtrasie doeltreffendheid van vesel filters hang af van die mikro-strukturele karakterisering van hierdie poreuse materiale en word gereflekteer in die permeabiliteit. Kompressie van veselagtige poreuse media het ’n beduidende effek op die permeabiliteit. Eksperimentele data dui aan dat die verandering in permeabiliteit gewoonlik oor meer as ’n orde grootte strek oor die klein porositeitsinterval waarin die kompressie plaasvind. Relatief tot die aantal eksperimentele studies rakende hierdie verskynsel, is daar ’n tekort aan geometriese modelle in die literatuur wat die effek van kompressie op die permeabiliteit van veselagtige poreuse media in ag kan neem. Binne die konteks van bestaande geometriese kanaal-skaal modelle gebasseer op reghoekige geometrie, is ’n nuwe model voorgestel en ’n bestaande model verbeter om die effek van een-dimensionele kompressie in die stroomsgewyse rigting te voorspel. Sonder om die verbintenis tot wiskundige eenvoud prys te gee, is empiriese data van ’n nie-geweefde veselagtige poreuse medium gebruik om die effek van die geometrie van ’n model op sy voorspellingsvermo¨e uit te lig. Verskillende wiskundige uitdrukkings is oorweeg vir die verband tussen kompressie en porositeit. Die permeabiliteit is eksplisiet uitgedruk in terme van die veseldiameter en die kompressie breukdeel en implisiet in terme van die porositeit. Die porositeit is ge-inkorporeer deur die verhouding tussen die lineêre dimensies van die geometriese model. Die algemene toepaslikheid van die model(le) is gestaaf deur gebruik te maak van data oor lugvloei deur ’n sagte veselagtige poreuse materiaal sowel as deur glas en nylon vesels. Die voorspellings van die permeabiliteit val binne dieselfde groote orde as die eksperimentele data. Gegee die wiskundige eenvoud van die model(le), is die voorspellingsvermoë bevredigend. Aandag is gevestig op aannames wat gemaak is en modelbeperkings binne die analitiese modellerings prosedure. ’n Algemene voorspellingsvergelyking is voorgestel vir die voorspelling van die permeabiliteit waarin ’n vaste stof distribusie faktor geinkorporeer is. Die voorgestelde modelle dien as basis vir verdere aanpassing en verfyning van voorspellingsvermoë.
18
Sweeney, Benjamin Andrew. "The Effect of Biocomposite Material In A Composite Structure Under Compression Loading." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1932.
Abstract:
While composite structures exhibit exceptional strength and weight saving possibilities for engineering applications, sometimes their overall cost and/or material performance can limit their usage when compared to conventional structural materials. Meanwhile ‘biocomposites’, composite structures consisting of natural fibers (i.e. bamboo fibers), display higher cost efficiency and unique structural benefits such as ‘sustainability’. This analysis will determine if the integration of these two different types of composites are beneficial to the overall structure. Specifically, the structure will consist of a one internal bamboo veneer biocomposite ply; and two external carbon fiber weave composite plies surrounding the bamboo biocomposite. To acquire results of this study, the hypothesized composite structure will consist of varied trapezoidal corrugated specimens and tested in uniaxial compression loading. Thereafter, this test data will be used to ultimately design, manufacture, and test a structural biocomposite/composite box, intended to carry extremely high compressive loads; relative to its own weight. A finite element analysis of this test will be used to validate experimental data. After running the experiment, the carbon fiber with bamboo test sample results were compared to that of only carbon fiber test sample. The carbon fiber samples resulted in a maximum compressive load difference of only 23% higher loads when compared to the carbon fiber with bamboo, on average. These findings are discussed throughout.
19
Hartley, R. S. "Assessing the effect of friction on compression split Hopkinson pressure bar tests." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/19571.
Abstract:
An enhanced understanding of material behaviour during rapid loading allows designers to improve the safety and efficiency of industrial processes and commercial products. These improvements are due, in part, to the use of increasingly powerful and sophisticated numerical simulation codes, which in tum, depend on accurate high strain rate material data. A Split Hopkinson Pressure Bar (SHPB) facility had previously been developed at the University of Cape Town to allow high strain rate testing of materials in compression. However, uncertainties regarding aspects of the test method that can affect the accuracy of the results, such as interface friction and specimen inertia, still required further clarification. This report details a thorough experimental and numerical investigation into the effect of friction on SHPB test data. The objectives are to assess the magnitude of the effect of friction under various conditions and to suggest strategies for reducing friction error in SHPB tests to an acceptable level. The ring compression test was used to obtain experimental friction factors. The effect of surface finish, lubricant, and strain rate on the friction experienced by mild steel, copper and aluminium samples was investigated. Numerical simulation was used to assess an energy-based analytical solution by Avitzur [1], and in particular to establish the effect of neglecting barrelling. Avitzur's analytical solution [l] Was then used to interpret the experimental results. The tested specimen microstructure was examined and used to estimate the stress distribution in the specimen during deformation. Uneven deformation and fold-over diminished at higher strain rates. Optimal surface finish and lubricant conditions were found for which experimentally measured coulomb friction coefficients lay between J.l = 0.04 and 0.08, with copper samples exhibiting marginally higher friction. By Avitzur's analytical solution [1] the error in SHPB tests under these recommended conditions was estimated to lie between 1% and 2%. The results show that roughened compression and specimen surfaces, lubricated with a suitable grease containing molybdenum disulphide, are useful in effectively reducing the error in SHPB tests due to friction effects.
20
Cambridge, Shevonn Nathaniel. "The effect of compression ratio on emissions from an alcohol-fueled engine." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09122009-040220/.
21
Schwartz, Andrew H. "Effect of dynamic range compression on attending to sounds based on spatial location." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84411.
Abstract:
Thesis (Ph. D. in Speech and Hearing Bioscience and Technology)--Harvard-MIT Program in Health Sciences and Technology, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 118-125).
Many hearing aids introduce nonlinear compressive gain to accommodate the reduced dynamic range that often accompanies hearing loss. Unfortunately, when applied independently at either ear, this gain can introduce fluctuations in interaural level difference (ILD), which is an important cue for spatial perception and attending to sounds in an acoustic mixture. Moreover, natural sounds produce complicated interactions between different sounds in a mixture, as a compressor's gain is driven by whichever source dominates the mixture within a specified temporal window. While independent compression can interfere with spatial perception of sound, it does not always interfere with localization accuracy or speech identification. This thesis investigates the role of dynamic range compression on the ability to attend to target speech in the presence of interfering speech. First, the fundamental concepts behind dynamic range compression and its use are introduced, and used to develop a framework to understand some of the possible effects on ILD and spatial perception. This framework is applied toward the interpretation of the existing literature regarding dynamic range compression and spatial perception, bringing together a seemingly contradictory range of results. In particular, the framework presented here predicts that dynamic range compression will only affect performance in tasks for which relatively small spatial separations are tested, whereas many existing studies compare only large spatial separations to no spatial separation. We describe and analyze the results of an experiment designed to test this prediction by systematically varying the spatial separation between different speech sources that normal-hearing listeners attended to. We found a robust but modest detrimental effect of dynamic range compression on listeners' performance. Linking the left and right compressors so that ILD was unaltered restored performance. Lastly, we develop a model to describe the utility of ILD for such tasks. The results of this model provide insight into the reported behavioral results, and generate predictions for how hearing impairment may alter the observed pattern of results.
by Andrew H. Schwartz.
Ph.D.in Speech and Hearing Bioscience and Technology
22
Grobler, Lara. "The effect of graduated compression socks on calf muscle oxygenation of endurance athletes." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71677.
Abstract:
Thesis (M Sport Sc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Compression socks (CS) are used as an ergogenic aid during and after exercise by many athletes of elite and recreational status. The exact mechanism whereby CS affect performance and postexercise recovery is not yet elucidated. Some research ascribes the beneficial effects to improved lactate removal rates with CS. One hypothesis is that CS improve venous return and thereby remove the lactate from the tissue to other tissues such as the liver, and the second hypothesis is that the CS cause retention of the lactate within the muscle and therefore improve the oxidation of the lactate within the muscle (Berry & McMurray, 1987). The current study endeavoured to test the hypothesis set by Berry and McMurray (1987) by measuring the effect of CS as well as flight socks (FS) on muscle oxygenation during exercise and recovery in endurance trained runners and triathletes. Eleven male endurance trained runners and triathletes (age = 34.8 ± 3.8 years, VO2max = 52.4 ± 7.1 mL.kg-1.min-1) participated in the study. They completed an incremental exercise test to exhaustion to determine their maximal aerobic capacity (VO2max) and peak treadmill velocity (PTV). Then they completed two 10 km treadmill running tests at 80 % of their PTV. During these two trials participants wore either CS or FS; the order of treatment was randomly selected. A subset of the study sample (n = 5) also completed a control test wearing only their ankle length sport socks (NS). After these trials, participants completed a 60 minute passive recovery period in the seated position while muscle oxygenation was measured. Compression under the socks was measured at several anatomically determined measurement points prior to the commencement of the exercise test, along with the determination of blood haemoglobin concentration ([Hb]). During the exercise trials, blood lactate concentration ([BLa]), skin temperature (ST),oxygen consumption (VO2), carbon dioxide production (VCO2), heart rate (HR), and muscle oxygenation variables (oxy-haemoglobin (O2Hb), deoxy-haemoglobin (HHb), tissue oxygenation index (TOI) and total haemoglobin index (nTHI)) was measured . During the 60minute passive recovery period, [BLa], ST, O2Hb, HHb, TOI, and nTHI measurements were continued. The results showed that there were differences in the pressure exerted between the two pressure condition (CS and FS) at the posterior ankle, and under the elastic of the sock as well as on the anterior calf at the level of greatest calf circumference. Differences in ST between the CS and NS and the FS and NS conditions were found between the first four 2 km intervals of the exercise protocol, but not during recovery. No differences were found in [BLa] between the three different compression conditions during either the exercise (p = 0.19) or recovery period (p = 0.63), as well as no differences in the cardiorespiratory variables during exercise between the three different compression conditions (VO2, p = 0.06; VCO2, p = 0.12; HR, p = 0.36). With regard to the muscle oxygenation variables, no differences were found between the three compression conditions during exercise, however there was a trend for lower oxygen utilization (HHb) during exercise in the NS condition (p = 0.57, medium to large practical significance). There were also no differences in these variables (O2Hb, p = 0.65; HHb, p = 0.57; TOI, p = 0.39; nTHI, p = 0.22) during recovery, although oxygen utilization (HHb) showed a faster recovery rate with increasing external pressure. From the results obtained, it seems that external compression caused a decrease in the blood flow velocity within the muscle, thereby increasing oxygen diffusion rate. During exercise this did not facilitate differences in [BLa], however, after the first 10 minutes of the recovery period, large practical differences were found between the NS and both sock conditions, suggesting that the increase in oxygen diffusion improved lactate clearance. This could support the hypothesis set by Berry and McMurray (1987).
AFRIKAANSE OPSOMMING: Kompressie sokkies (CS) word gereeld deur beide rekreasie- en elite atlete gebruik as ‘n ergogeniese hulpmiddlel tydens oefening en herstel. Die presiese meganisme waardeur CS prestasie en post-oefening herstel beïnvloed is nog nie volledig verklaar nie. Sommige navorsing skryf die voordelige effekte toe aan die vinniger herstel van laktaat in die sirkulasie. Daar is tans twee hipoteses vir die meganisme waardeur CS laktaat verwydering verbeter. Die eerste hipotese is dat CS die veneuse terugvoer verbeter en daardeur die laktaat van die weefsel verwyder en na ander weefsels soos die lewer vervoer vir verwydering. Die tweede hipotese is dat CS veroorsaak dat die laktaat in die spierweefsel teruggehou word wat dan tot gevolg het dat die laktaat in die spier self deur middel van oksidasie verwyder word (Berry & McMurray, 1987). Hierdie studie poog om Berry en McMurray (1987) se hipotese te toets deur die effek wat CS sowel as vlugsokkies (FS) op spieroksigenasie het gedurende oefening en herstel in geoefende uithouvermoë hardlopers en driekamp atlete vas te stel. Elf ingeoefende langafstand hardlopers en driekampatlete (mans) (ouderdom = 34.8 ± 3.8 jaar; VO2maks = 52.4 ± 7.1 mL.kg-1.min-1) het aan hierdie studie deel geneem. Die deelnemers het ‘n inkrementele toets tot die punt van uitputting voltooi om hul maksimale aërobiese kapasiteit (VO2maks) en piek trapmeul snelheid (PTV) vas te stel. Die elf deelnemers het ook twee 10 km hardlooptoetse teen 80 % van hul PTV voltooi. Gedurende hierdie twee toetse het die deelnemers óf CS óf FS gedra; die volgorde van die intervensie was lukraak aan hulle toegeken. ‘n Subgroep van die steekproef (n = 5) het ook ‘n kontrole toets voltooi waartydens hulle hul eie enkelhoogte sport sokkies (NS) gedra het. Aan die einde van die hardloop protokol het die deelnemers ‘n 60 minuut passiewe herstel periode in die sittende posisie voltooi terwyl spieroksigenasie gemeet is. Kompressie onder die sokkies is voor die aanvang van die hardloop protokol by verskeie anatomies gedefinieerde punte gemeet. Verder was die bloed hemoglobien konsentrasie ([Hb]) ook gemeet voor die hardloop protokol. Tydens die oefeningtoets is bloedlaktaat konsentrasie ([Hb]), veltemperatuur (ST), suurstof verbruik (VO2), koolstofdioksied produksie (VCO2), harttempo (HR), sowel as spieroksigenasie veranderlikes (oksi-hemoglobien (O2Hb), deoksi-hemoglobien (HHb), weefsel oksigenasie indeks (TOI), en totale hemoglobien indeks (nTHI)) gemeet. Gedurende die 60 minuut passiewe hersteltydperk is [BLa], ST, O2Hb, HHb, TOI en nTHI metings geneem. Die resultate toon dat daar ‘n verskil is in die druk wat uitgeoefen word in die onderskeie druktoestande (CS en FS) op die been by die posterior enkel en onder die rek van die sokkie, sowel as op die anterior kuit waar die kuit die grootste omtrek het. Verdere verskille tussen die CS en NS en die FS en NS toestande is in ST gevind in the eerste vier 2 km intervalle van die oefeningtoets, alhoewel geen verskille tydens die herstelperiode gevind is nie. Tydens beide die oefening (p = 0.19) en herstel (p = 0.63) protokol is geen verskille tussen die drie kompressie toestande met betrekking tot [BLa] gevind nie. En so ook is daar geen verskille tussen die onderskeie kompressie toestande in kardiorespiratoriese veranderlikes (VO2, p = 0.06; VCO2, p = 0.12; HR, p = 0.36) tydens oefening gevind nie. Met betrekking tot spieroksigenasie veranderlikes was daar geen verskil gevind tussen die drie kompressietoestande gedurende oefening nie, alhoewel daar ‘n tendens was vir die NS toestand om tydens oefening minder suurstofverbruik (HHb) (p = 0.57, medium tot groot praktiese effek) te lewer. So ook gedurende herstel is daar geen verskil in hierdie veranderlikes (O2Hb, p = 0.65; HHb, p = 0.57; TOI, p = 0.39; nTHI, p = 0.22) gevind nie, alhoewel die suurstofverbruik (HHb) vinniger na die basislyn herstel het met ‘n toename in druk. Die resultate toon dat eksterne kompressie ‘n afname in die bloedvloei tempo in die spier veroorsaak wat dan ‘n verlengde suurstof diffusie tyd veroorsaak. Hierdie verlengde suurstof diffusie tyd het geen effek op [BLa] tydens oefening gehad nie, alhoewel daar na die eerste 10 minute van die herstelperiode ‘n groot praktiese verskil tussen die NS en sokkie toestande gevind was in [BLa]. Hierdie verskil kan daarop dui dat die toename in suurstof diffusie verbeterde laktaat verwydering tot gevolg het, wat dan die hipotese van Berry en McMurray (1987) ondersteun.
23
Kirk, Linda S. "The effect of gap size on performance of metal plated joints in compression." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53170.
Abstract:
Metal plate splice joints with gaps between butting pieces of lumber were tested in compression to evaluate the effect of gap size on joint serviceability performance. The current design methodology for compression splice joints was also evaluated. Specimens representing floor and roof trusses, with 16 and 20 gauge plates of staggered and aligned tooth configurations were tested for each of two gap sizes.
Generally, 20 gauge plates and 16 gauge plates with 1/8” gaps buckled under compression loads while 16 gauge plates with 1/16" maximum gap did not buckle before the gap closed; rather, the gap closed primarily due to slippage between the teeth and the wood. 16 gauge plates generally outperformed 20 gauge plates based on serviceability performance of the test compression splice joints. Furthermore, gap size had less of an influence on joints with 16 gauge plates than on joints with 20 gauge plates.
The current practice of sizing plates for compression splices to withstand one-half of the calculated chord force could not be physically confirmed using the study joint serviceability criteria. The test results indicate that basing allowable plate ratings on a per area basis derived from tension tests is misleading.Master of Science
24
Eyre, Michael Reese Kaczor Nancy Ann. "The effect of flexographic printing on the compression strength of corrugated shipping containers /." Online version of thesis, 1990. http://hdl.handle.net/1850/11178.
25
Light, K., and Earl E. Johnson. "The Effect of Varying Amounts of Nonlinear Frequency Compression on Amplified Sound Quality." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/1756.
26
Bree, Carsten. "Self-compression of intense optical pulses and the filamentary regime of nonlinear optics." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16430.
Abstract:
Diese Arbeit beschäftigt sich mit Femtosekunden-Filamenten in dispersiven, transparenten Medien. Die Erzeugung optischer Femtosekunden-Impulse durch Selbstkompression in Edelgasen wird unter theoretischen und experimentellen Aspekt behandelt, wobei die zugrundeliegenden physikalischen Mechanismen aufgezeigt werden. Dazu werden numerische Simulationen hochintensiver Femtosekunden-Impulse in Edelgasen durchgeführt, und eine analytische Beschreibung der Selbstkompression wird entwickelt. Im experimentellen Teil der Arbeit wird eine bisher nur theoretisch vorhergesagte Selbstheilungseigenschaft des zeitlichen Impulsverlaufs in Femtosekunden-Filamenten nachgewiesen. Es wird gezeigt, dass die zeitliche Impulsform stabil gegenüber einer adiabatisch einsetzenden, temporären Zunahme von Dispersion und Nichtlinearität um jeweils drei Größenordnungen ist, wie sie beim Durchgang durch das Austrittsfenster einer gasgefüllten Zelle auftritt. Die optische Feldstärke in Filamenten ist vergleichbar mit inneratomaren Bindungskräften. Bei derart hohen Intensitäten treten hochgradig nichtlineare Effekte wie Multiphoton- oder Tunnelionisation auf. Neuere experimentelle Befunde deuten an, dass die Sättigung des optischen Kerr-Effekts eine entscheidende Rolle in Filamenten spielt, im Gegensatz zur bisherigen Annahme der Sättigung der optischen Nichtlinearität durch freie Ladungsträger. Dieser Befund wird derzeit in der Literatur kontrovers diskutiert. Im Rahmen dieser Arbeit wird ein unabhängiger theoretischer Ansatz verfolgt, um Beiträge hoher Ordnungen zum optisch-optischen Kerr-Effekt aus einer Kramers-Kronig Transformation des Multiphoton-Absorptionskoeffizienten abzuschätzen. Auschließlich ausgehend von physikalischen Grundprinzipien sowie einiger moderater Näherungen stützen diese Ergebnisse ein kürzlich vorgeschlagenes Modell, welches relevante Beiträge höherer Ordnung zum optisch-optischen Kerr-Effekt vorhersagt.This thesis discusses femtosecond filaments in dispersive dielectric media. In particular, the generation of intense, few-cycle optical pulses due to self-compression in noble gases is analyzed from a theoretical as well as from an experimental viewpoint, clearly isolating the physical mechanisms behind the observed pulse self-compression mechanism. To this end, numerical simulations of high-intensity femtosecond pulses propagating in noble gases were performed, and an analytical model of the processes leading to pulse self-compression was developed. Moreover, a theoretically predicted temporal self-healing property of femtosecond filaments is experimentally proven, demonstrating that few-cycle optical pulses can recover and even benefit from a temporary, non-adiabatic increase of dispersion and nonlinearity of the order of three magnitudes as experienced during the passage from a gaseous medium to a thin silica sample. Filamentation sets in at field strengths that approach the order of inner-atomic binding forces. At these extreme intensities, highly nonlinear effects such as multiphoton ionization or tunneling effects occur. Recent experimental investigations claim a prevalent contribution of a saturation of the optical Kerr effect in filamentation prior to the onset of Drude-contributions from ionization effects. This finding is currently controversially discussed in literature. In this thesis, an independent theoretical approach was pursued, estimating high-order contributions to the all-optical Kerr effect via a Kramers-Kronig transform of multiphoton absorption cross-sections. Quite surprisingly, while only based on first principles with some moderate approximations, the results of this analysis are in strong support of the recently suggested higher-order Kerr model.
27
Choi, Sangsook. "The effect of compression on speech perception as reflected by attention and intelligibility measures." [Lincoln, Neb. : University of Nebraska-Lincoln], 2004. http://www.unl.edu/libr/Dissertations/2004/ChoiDis.pdf.
Abstract:
Thesis (Ph. D.)--University of Nebraska--Lincoln, 2004.PDF text: [1] leaf abstract, v, 64 leaves dissertation : ill. (some col.). Site viewed on Jan. 25, 2005. Includes bibliographical references (leaves [65-70] of dissertation).
28
Gomez, Rafael. "The effect of social capital, salary compression and equity on individual and organizational performance." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0025/NQ49916.pdf.
29
Stadler, Daniel. "The effect of abdominal compression on UA function during sleep in healthy weight males /." Title page and abstract only, 2004. http://web4.library.adelaide.edu.au/theses/09SB/09sbs7771.pdf.
30
Northcutt, Sheri Lynn. "Effect of particle fabric on the one-dimensional compression response of Fraser River sand." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/18162.
Abstract:
One-dimensional compression of sand with lateral stress measurement allows for laboratory determination of the coefficient of lateral pressure at rest, Ko. Commonly used to define the initial state of stress in soil where no lateral strain occurs, Ko is calculated as the ratio of horizontal to vertical effective stress. The present study aims to investigate the role of initial particle fabric in one-dimensional compression and to determine the effect of fabric on the coefficient of lateral pressure at rest in Fraser River sand. One-dimensional compression with lateral stress measurement was carried out on reconstituted Fraser River sand specimens using an instrumented oedometer. Laboratory specimen reconstitution methods were developed in order to construct different particle fabrics. Three different techniques were utilized: air pluviation, tamping and vibration. In addition, the effects of initial relative density and loading history on the compression response were evaluated. Each one-dimensional compression test was executed in three distinct phases: virgin loading, unloading and reloading. The key results from the testing program were compared with current methods available for estimation of Ko. The results from the present study show that specimens resulting from different laboratory reconstitution methods (i.e., initial particle fabrics) exhibit different one-dimensional compression responses. For Fraser River sand in one-dimensional compression, air-pluviated specimens yield the highest Ko values, tamped specimens produce the lowest Ko values and vibrated specimens rank intermediate. With increasing initial relative density, regardless of the initial specimen preparation method, the measured Ko values generally decrease. Upon reloading, measured Ko values are slightly reduced from those observed during virgin loading. Furthermore, results from the present study indicate that the current methods commonly used for determination of Ko do not necessarily provide suitable estimations for variable granular particle fabrics arising from different specimen reconstitution techniques. A new method for determination of Ko is proposed, as a function of the constant-volume friction angle, initial relative density and a factor accounting for the initial particle fabric.
31
Aivaz, Balian Razmik. "The effect of compression ratio on the performance of a direct injection diesel engine." Thesis, Brunel University, 1990. http://bura.brunel.ac.uk/handle/2438/11249.
Abstract:
This thesis considers the effect of compression ratio on the performance of a direct injection diesel engine. One aspect of engine performance is considered in great detail, namely the combustion performance at increased clearance volume. This aspect was of particular interest because variable compression ratio (VCR) systems normally operate by varying the clearance volume. The investigation relied upon results obtained both from experimental and computer simulating models. The experimental tests were carried out using a single-cylinder direct-injection diesel engine, under simulated turbocharged conditions at a reduced compression ratio. A number of one-dimensional computer models were developed; these simulate the induction and compression strokes, and the fuel spray trajectories in the presence of air swirl. The major objectives of the investigation were: to assess the benefits of VCR in terms of improvements in output power and fuel economy; to assess the effects on combustion of increased clearance volume, and investigate methods for ameliorating resulting problems; develop computational models which could aid understanding of the combustion process under varying clearance volume conditions. It was concluded that at the reduced compression ratio of 12.9:1 (compared to the standard value of 17.4:1 for the naturally-aspirated engine), brake mean effective pressure (BMEP) could be increased by more than 50%, and the brake specific fuel consumption (BSFC) could be reduced by more than 20%. These improvements were achieved without the maximum cylinder pressure or engine temperatures exceeding the highest values for the standard engine. Combustion performance deteriorated markedly, but certain modifications to the injection system proved successful in ameliorating the problems. These included: increase in the number of injector nozzle holes from 3 to 4, increase in injection rate by about 28%, advancing injection timing by about 6°CA. In addition, operation with weaker air fuel ratio, in the range of 30 to 40:1 reduced smoke emissions and improved BSFC. Use of intercooling under VCR conditions provided only modest gains in performance. The NO emission was found to be insensitive to engine operating conditions (fixed compression ratio of 12.9:1), as long as the peak cylinder pressure was maintained constant. Engine test results were used in order to assess the accuracy of four published correlations for predicting ignition delay. The best prediction of ignition delay with these correlations deviated by up to 50% from the measured values. The computer simulation models provided useful insights into the fuel distribution within the engine cylinder. It also became possible to quantify the interaction between the swirling air and the fuel sprays, using two parameters: the crosswind and impingement velocities of the fuel spray when it impinges on the piston-bowl walls. Tentative trends were identified which showed that high crosswind velocity coincided with lower smoke emissions and lower BSFC.
32
Sanderson, I. M. "The effect of formulation and maufacturing processes on the characterisitics of direct compression tablets." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372670.
33
Andreae, Morgan M. (Morgan MacKenzie). "Effect of ambient conditions and fuel properties on homogeneous charge compression ignition engine operation." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35616.
Abstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 197-198).
Practical application of Homogeneous Charge Compression Ignition (HCCI) combustion must demonstrate robust responses to variations in environmental conditions. This work examines the impact of ambient conditions and fuel changes on HCCI engine operation, and evaluates cam phasing as a mechanism to compensate for these changes. Experiments were carried out on a modified 2.3 L 14 production engine, and HCCI operation was achieved by the use of residual trapping by negative valve overlap. The first phase of the project examined the impact of changes in intake air temperature and humidity on HCCI operation. Exhaust cam phasing was used to control load, and intake cam phasing was use to produce a change in combustion phasing. Cam timing control was largely able to compensate for changes in combustion due to changes in air temperature and humidity. Higher intake air temperature advanced combustion phasing and resulted in a 1 bar reduction of the net indicated mean effective pressure (NIMEP) at the high load limit for lower engine speeds. Intake air temperature did have more of an impact during lean operation. Higher intake air humidity delayed combustion phasing.
(cont.) During stoichiometric operation, this delay allowed a small extension (a few tenths of a bar in NIMEP) in the high load limit. During lean operation, the delay in combustion timing resulted in a reduction of the high load limit. The second phase of the project examined the impact of market fuel composition variations on HCCI operation. Twelve test fuels were created to vary the composition of 5 fuel properties: Research Octane Number (RON), Reid Vapor Pressure (RVP), olefin content, aromatic content, and ethanol content. The test fuels were blends of different commercial refinery streams and contained hundreds of different hydrocarbons to be representative market gasolines. Fuel type was found to have only a small impact on the HCCI operating range, and cam phasing was largely able to compensate for changes in fuel composition. The main effect of the different fuel composition appeared to be differences in ignition delay.
by Morgan M. Andreae.
Ph.D.
34
Baker, Matthew W. "Effect of Pallet Deckboard Stiffness and Unit Load Factors on Corrugated Box Compression Strength." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/79367.
Abstract:
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.
35
Abdelkarim, Ahmad Ali. "Effect of JPEG2000 compression on landmark identification of lateral cephalometric digital radiographs a thesis /." San Antonio : UTHSC, 2008. http://learningobjects.library.uthscsa.edu/cdm4/item_viewer.php?CISOROOT=/theses&CISOPTR=57&CISOBOX=1&REC=16.
36
Wouts, Jérémy. "Étude et modélisation du comportement en compression du bois sous sollicitations d'impacts." Thesis, Valenciennes, 2017. http://www.theses.fr/2017VALE0025.
Abstract:
Le bois est un matériau cellulaire naturel et excellent absorbeur d’énergie. Employé au sein de structures du type limiteur d’impact, il subit de nombreux phénomènes lors d’un cas de chute. Une large campagne expérimentale est réalisée afin d’analyser les réponses en compression du hêtre et de l’épicéa, en fonction de la direction de sollicitation, de la vitesse de déformation pour la plage [0.001-600] s−1 et de deux types de restrictions latérales qualifiées d’extrêmes. La direction longitudinale se révèle la plus sensible à la vitesse ainsi qu’au type de restrictions latérales et les conséquences sur la capacité d’absorption d’énergie du bois sont alors significatives. Par ailleurs, les protocoles développés ont vocation à être déclinés pour un large panel d’essences aux propriétés mécaniques variées. Un modèle matériau élastoplastique, isotrope transverse et sensible à la vitesse de déformation est élaboré à l’aide des techniques multi-échelles et de la micromécanique. Les propriétés élastiques macroscopiques sont estimées à l’aide du schéma d’homogénéisation de Mori-Tanaka à partir de données issues de la microstructure. Un critère de type Gurson étendu reposant sur l’approche micromécanique de l’endommagement ductile est employé pour retranscrire le comportement non linéaire, la densification et le caractère compressible du bois. Des paramètres de dégradation découplés du critère sont appliqués selon la direction longitudinale. La modélisation proposée repose sur une description simplifiée du bois et les résultats numériques associés illustrent la bonne capacité du modèle à reproduire les différentes réponses observées lors d’un cas de chuteWood is a natural cellular material, which is widely and advantageously used as shock absorber for the transport of radioactive materials. Accident situations are evaluated based on the 9 m drop test, which allows us to observe the complex crushing behavior of wood. A compressive experimental study is conducted on spruce and beech wood species over a large range of strain rates (from 0.001 to 600 s−1) to investigate the effect of the loading direction and of two extreme lateral confinements. The longitudinal direction is the most sensitive to the effect of strain rate and of lateral confinements which have significant consequences on the energy absorption. Besides, the experimental investigation can be adapted to various wood species with very different mechanical properties. A strain rate dependent elastoplastic model with transversal isotropy is developed using multi-scale and micromechanics techniques. The elastic macroscopic properties of wood are estimated with a Mori-Tanaka scheme and information extracted from the microstructure. The Gurson type criterion based on the micromechanical approach of the ductile damage is used in order to describe the non linear behavior of wood, its densification regime and its compressibility as well. Additionally, uncoupled degradation parameters are applied to reproduce the failure mechanisms involved in the longitudinal response. A simplified description of wood is used within the modeling and the numerical results exhibit the good ability of the model to reproduce the various wood responses during an accident situation
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Baker, Christopher E. "The effect of transient dynamics of the internal combustion compression ring upon its tribological performance." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14068.
Abstract:
The losses in an internal combustion engine are dominated by thermal and parasitic sources. The latter arises from mechanical inefficiencies inherent within the system, particularly friction in load bearing conjunctions such as the piston assembly. During idle and at low engine speeds, frictional losses are the major contributor to the overall engine losses as opposed to the dominant contribution of thermal losses under other driving conditions. Given the relatively small size and simple structure of the top compression ring, it has a disproportionate contribution to the total frictional losses. This suggests further analysis would be required to understand the underlying causes of compression ring behaviour throughout the engine cycle. The available literature on tribological analyses of compression rings does not account for the transient ring elastodynamics. They usually assume a rigid ring for film thickness and power loss predictions, which is not representative of the ring's dynamic response. A combined study of ring elastodynamic behaviour and its tribological conjunction is a comprehensive approach.
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Tranter, Thomas George. "A study of water management in polymer electrolyte fuel cells : compression effect on multiphase flow." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16086/.
Abstract:
One of the main obstacles to overcome regarding the uptake of renewable energy technologies, specifically wind and solar energy, is their intermittency. Current energy storage techniques are costly and in-efficient. Fuel cells are a promising candidate for future energy storage, as part of an integrated system combining renewable energy with hydrogen production as the storage vector with reconversion. The Polymer Electrolyte Fuel Cell (PEFC) has the greatest potential for use with micro-generated renewable power and is suitable for the widest range of applications. Hence it has received a great deal of attention from research institutions and industry over the last few decades. However, they suffer performance limitations due to flooding by liquid water in the porous components forming the electrodes of the cell. Two numerical investigations utilising different methods to probe multiphase transport in porous media, and one experimental investigation into the flow through partially saturated porous media, are presented. The porous media under investigation are typical materials for PEFC gas diffusion layers (GDLs), and the influence of compression of the material on the multiphase transport is investigated. In addition, a further study assessing the suitability of pore-scale capillary pressure models for predicting multiphase flow behaviour is included as a final research chapter.
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Nagy, Caitlin Sandra. "EFFECT OF INTERMITTENT PNEUMATIC COMPRESSION (IPC) ON GLUCOSE REGULATION AND INFLAMMATION IN TYPE 2 DIABETES." Cleveland State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=csu1525784446631762.
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Alkhtany, Moshabab Mobarek H. "MODELING STRUCTURAL POLYMERIC FOAMS UNDER COMBINED CYCLIC COMPRESSION-SHEAR LOADING." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1469532064.
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Dunford, Jason Allen. "Development of an instrument to determine the effect of cyclic transverse compression on wood-pulp fibres." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0014/MQ52895.pdf.
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St, Onge Paul Michael. "Effect of tissue compression on the Hoffmann reflex comparison between the ischial tuberosity and posterior thigh /." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Spring%20Dissertations/ST_ONGE_38.pdf.
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Lafferty, Ian. "The effect of crystallisation variables on the powder characteristics, mechanical properties and compression behaviour of dextrose." Thesis, De Montfort University, 1998. http://hdl.handle.net/2086/4185.
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Quesenberry, Chandler Blake. "The Effect of Pallet Top Deck Stiffness on the Compression Strength of Asymmetrically Supported Corrugated Boxes." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/104965.
Abstract:
During unitized shipment, the components of unit loads are interacting with each other. During floor stacking of unit loads, the load on the top of the pallet causes the top deck of the pallet to bend which creates an uneven top deck surface resulting in uneven, or asymmetrical support of the corrugated boxes. This asymmetrical support could significantly affect the strength of the corrugated boxes, and it depends on the top deck stiffness of the pallet. This study is aimed at investigating how the variations of pallet top deck stiffness and the resulting asymmetric support, affects corrugated box compression strength.
Pallet top deck stiffness was determined to have a significant effect on box compression strength. There was a 27-37% increase in box compression strength for boxes supported by high stiffness pallets in comparison to low stiffness pallets. The fact that boxes were weaker on low stiffness pallets could be explained by the uneven pressure distribution between the pallet deck and bottom layer of boxes. Pressure data showed that a higher percentage of total pressure was located under the box sidewalls that were supported on the outside stringers of low stiffness pallets in comparison to high stiffness pallets. This was disproportionately loading one side of the box.
Utilizing the effects of pallet top deck stiffness on box compression performance, a unit load cost analysis is presented showing that a stiffer pallet can be used to carry boxes with less board material; hence, it can reduce the total unit load packaging cost.Master of Science
Packaged products are primarily shipped as unit loads that consist of packaged products restrained to a platform, commonly a pallet. Paying particular attention to the design of the unit loads' components is necessary to safely ship products while still maintaining low packaging costs and sustainability initiatives. Stacking unit loads is a common practice to effectively use warehouse space, but warehouse stacking causes large amounts of weight for packaging to support. Pallets are not completely rigid and will deform because of this weight. The purpose of the study was to investigate the effect of pallet stiffness on the compression strength of corrugated boxes. Compression tests were completed on boxes supported by pallet designs having different deck stiffnesses. The top deck stiffness of a pallet was determined to have up to a 37% effect on the strength of corrugated boxes. Pressure data recorded between the bottom layer of boxes and the top deck of the pallet showed a larger percentage of pressure was located towards the outside edges of the unit load for boxes carried by a flexible pallet. Effectively, one side of the box was stressed more than the other causing package failure. Utilizing the effects of pallet top deck stiffness on box compression performance, a unit load cost analysis is presented showing that a stiffer pallet can be used to carry boxes with less board material; hence, it can reduce the total unit load packaging cost.
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Phanthanousy, Samantha. "The Effect of the Stiffness of Unit Load Components on Pallet Deflection and Box Compression Strength." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/86203.
Abstract:
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
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Chomier, Mickael Thierry. "Effect of Vortex Roll-up and Crevice Mass Flow on Ignition in a Rapid Compression Machine." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1374666527.
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Lukyanets, Yuliya. "The Green and Ampt Infiltration Model Accounting for Air Compression and Air Counterflow in the Shallow Water Table Environment: Laboratory Experiments." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3471.
Abstract:
Water infiltration into the unsaturated zone especially in a shallow water table environment is affected by air compression ahead of the wetting front and air counterflow. Neglecting air compression in infiltration modeling can overestimate infiltration and infiltration rates, whereas not accounting for air counterflow can underestimate infiltration and infiltration rates due to unrealistic buildup of air pressure resistance ahead of the wetting front. A method, derived on the basis of the Green and Ampt (1911) infiltration model, is introduced to simulate air compression and air counterflow during infiltration into a shallow water table. The method retains the simplicity of the Green and Ampt (1911) model but adds the air pressure resistance term ahead of the wetting front. Infiltration equations are derived on the basis of the Green and Ampt (1911) and Sabeh’s (2004) infiltration model which accounts for air compression and air counterflow. The difference between this method and Sabeh’s (2004) model is that air counterflow, air compression, and infiltration are decoupled and updated with each wetting front increment whereas Sabeh’s (2004) method uses time step as a decoupling mechanism. Air compression ahead of the wetting front is predicted using the perfect gas law.
Laboratory experiments showed that the introduced method is reasonably accurate when modeling cumulative infiltration values. Results of laboratory experiments were compared to results of the modeled infiltration methods: original Green and Ampt (1911) model and Green and Ampt with air compression and counterflow.
The advantage of this new method is its simplicity. The new method uses parameters that are generally needed for modeling infiltration with the Green and Ampt (1911) approach. Disadvantages of the model are assumptions of the uniform water content and the uniform pressure. Another shortcoming of the model is that it does not account for air compression and air counterflow prior to ponding.
Laboratory experiments described in this work and a proposed model can be further used for modeling and studying infiltration with air effects. In addition, this work can be of use to someone studying irrigation techniques of rice or other crops.
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Jenstad, Lorienne M. "The effect of temporal envelope changes on recognition of normal rate and time-compressed speech by young-old and old-old hearing-impaired listeners /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/8270.
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Swaminathan, Krishnakumar. "A quantitative proteomics study of the additive effect of inflammatory cytokines and injurious compression on cartilage damage." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67209.
Abstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 103-123).
Objectives: 1) To perform a quantitative comparison of proteins released to media on combination with cytokine (IL-1[beta[ or TNF-[alpha]) and Injury as compared to either treatment alone, and to thus identify proteins which may be responsible for the synergism seen between cytokine and injury in causing catabolism of cartilage in vitro. 2) To identify proteins which contribute most to some commonly observed phenotypes on treatment of cartilage with cytokine or injury or both. Methods : Cartilage explants from calves were treated with (i)IL-1 (10 ng/ml), (ii)TNF[alpha] (100 ng/ml), (iii)Injurious compression (50% strain at 100%/sec) and IL-1[beta] (10 ng/ml) or (iv)Injurious compression (50% strain at 100%/sec) and TNF-[alpha](10 ng/ml), cultured for 5 days post treatment, and the pooled media collected, labeled with one of four iTRAQ labels and subjected to nano-2D-LC/MS/MS on a quadrupole time of flight instrument. Peptides were identified and quantified using Protein PilotTM, and MATLAB scripts used to obtain protein ratios. These results were analyzed using different statistical techniques. Data from two iTRAQ experiments were combined to generate data for all possible injury and cytokine treatment conditions, and proteins on which injury and cytokines acted synergistically identified. PLSR analysis was performed using Unscrambler®X software with the combined data set to determine which proteins are most relevant to some observed phenotypes. The phenotypes chosen were sGAG released to media in 5 days post treatment, proline and sulfate incorporation rates on day 6 post treatment, and nitrite accumulation in media in 5 days post treatment Results and Discussion: TNF-[alpha]+injury and IL-[beta] +injury treatment conditions show a very high correlation with each other. Most cytosolic, ER lumen and nuclear protein levels are highly elevated with both cytokine+injury conditions, while ECM proteins are either highly down regulated or marginally elevated. Many collagen telopeptides are down regulated, possibly indicating reduced anabolism. However, attempts at repair exist, as shown by increased levels of TGF-[beta] and activin A, and reduced levels of LTBP1. Also, biglycan and lumican, SLRPs known to be involved in early development are significantly increased, possibly indicating repair attempts. Other SLRPs such as PRELP and chondroadherin are also highly elevated, with one or both injury+cytokine treatments. While MMPs are mildly down regulated or remain the same, ADAMTS1 increases with TNF-a+injury, indicating increased catabolism. Among ECM structural proteins, COMP shows high down regulation with TNF-[alpha]+injury, possibly due to reduced synthesis. Proenkephalin, a signaling molecule possibly involved in tissue/repair and apoptosis, AIMPI, a multifunctional proapoptotic, inflammatory and pro-repair cytokine and Annexin A5, a protein indicating mineralization and apoptosis are all highly elevated with cytokine+injury indicating heightened apoptosis and/or repair. When results of two 4-plex iTRAQ experiments are combined to obtain data for all possible combinations of injury and cytokine, we again find a very high correlation between TNF-a+injury and IL-1 +injury (-95%), slightly higher than the correlation between TNF-[alpha] alone and IL-[beta] alone (-90%), and much higher than the correlation of either cytokine+injury condition with cytokine alone (-70%) or injury alone (-75%).
(cont.) This shows that IL-1[beta] and TNF-[alpha] in combination with injury act through very similar pathways in chondrocytes to produce their effect on cartilage tissue. TNF-a and injury were seen to act synergistically in a positive fashion on aggrecan, CILP-2, COL6A3 and histone H4, and in a negative fashion on SPARC and IGFBP7, suggesting that these proteins may be involved in causing synergism between injury and cytokine in releasing sGAG to the media. A PLSR analysis shows that SPARC and IGFBP7 project close to proline and sulfate incorporation, and far away from sGAG, indicating that SPARC and IGFBP7 may be proteins involved in anabolism. The highest phenotype-protein positive correlations obtained using PLSR are sGAG with Perlecan, SAA3, Complement factor B, CILP-2 and pleiotropin, indicating that all these 5 proteins are associated strongly with catabolism and can serve as markers of catabolism. The correlation of inflammatory proteins SAA3 and complement factor B with sGAG indicates the role of inflammation with catabolism. Conclusion: The combination of injury and cytokine affects tissue differently at a molecular level as compared to either chemical or mechanical stresses alone. Increased catabolism and increased attempts at tissue repair are observed due to a combination of injury and cytokine, and a combination of injury and cytokine may thus serve as a useful model to study OA in vitro.
by Krishnakumar Swaminathan.
S.M.
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Mariola, Madison. "ACUTE EFFECT OF INTERMITTENT PNEUMATIC COMPRESSION (IPC) ON INFLAMMATION, CIRCULATION AND GLUCOSE REGULATION IN TYPE 2 DIABETICS." Cleveland State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=csu159259272116006.