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Residual stresses in paperboard and the influence of drying conditionsÖstlund, Magnus January 2005 (has links)
The drying sequence in the manufacturing process for paperboard involves evaporation of water, primarily from within the fibres. The vapour is then transported out of the web by pressure or concentration gradients. As the moisture transport from the paper web to the ambient is quicker than the moisture transport within the fibre network to the surfaces of the web, moisture gradients develop through the thickness of the web. This work concerns effects on the mechanics of paper drying from the variation in moisture through the relatively thin structures of paper and paperboard. Distributions of inplane residual stresses through paper materials in the unloaded state after drying are believed to be caused by the varying moisture through the thickness during drying. The distributions in general exhibit compressive stress near the board surfaces and tensile stress in the interior of the board. This may be modified after drying and is also affected by structural variation in the material between different plies of multi-ply paperboards. The stress development during drying is important because it influences the resulting material properties of the paper and because it can lead to curl, which is a quality problem. The residual stresses themselves are an error source in simulation or evaluation of the mechanical behaviour of paper. In this work, residual stress distributions in paperboard were determined experimentally, to clarify the mechanisms of residual stress build-up. An experimental method for such tests was also developed. Based on the experimental findings, the mechanics of paper drying was modelled and the stress build-up simulated. Simulation offers a way of studying how the properties of paper develop during drying of wet paper webs.
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Studies of Hysteresis and Residual Birefringence in Polymer Stabilized Blue Phases LC DisplayFan, Chun-Yuan 20 July 2011 (has links)
Blue-Phase liquid crystal display possesses potential to become next generation display technology because of its submillisecond response time, alignment-layer-free process and wide view angle. Intrinsically, BP only operates across a narrow temperature range due to the influence of intrinsic structural defects. Recently, the temperature range of BP has been successfully extended beyond 60K through the polymer-stabilized effect. Unfortunately, the structure of the polymer networks poses a number of problems, for instance, hysteresis effect, which degrades the accuracy of grayscale control, and residual birefringence, which decreases the contrast ratio of LCDs.
This paper investigates the voltage-induced hysteresis and residual birefringence in the polymer-stabilized blue phase I and II, under various phase separation conditions and material ratio. Based on experiment result, the polymer network morphology, distribution and pure BP temperature can result in a variety of PSBP electro-optical properties. Hysteresis and residual transmittance free PSBP display could be achieved by choosing appropriated phase separation condition and material ratio.
Key word¡Gblue phase¡Bmonomer¡Bhysteresis¡Bresidual transmittance
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Understanding Beef Cattle Efficiency: I) Understanding Physiological and Digestive Factors Affecting Residual Feed Intake and II) Tannin Supplementation: Effects on Animal Performance, Fermentation, and Carcass TraitsKrueger, Wimberley K. 2009 August 1900 (has links)
Objectives of this study were 1) to characterize the relationship between beef
cattle efficiency, namely residual feed intake (RFI), and digestive, microbial, and
fermentation parameters in growing beef calves and 2) to examine the effects of added
dietary hydrolysable or condensed tannin on animal performance and efficiency,
fermentation and carcass and non-carcass traits. To accomplish the first objective,
multiple RFI studies were conducted and in all studies RFI was calculated as the
difference between actual and expected dry matter intake (DMI) based on average gaily
gain (ADG) and body weight0.75(BW). A total of 187 head selected out of a population
of 600 head of growing beef calves were evaluated for diet and nutrient digestibility,
ruminal and fecal volatile fatty acids (VFA) concentrations and methane producing
activity (MPA). Low RFI calves consumed less DMI and had lower feed conversion
ratios (FCR) as compared to high RFI calves. Low RFI calves also had higher diet and
nutrient digestibilities compared to high RFI calves. Residual feed intake was negatively
correlated with diet and nutrient digestibilities such that more efficient animals had higher digestibilities. Low RFI calves tended to have lower ruminal propionate and
higher acetate:propionate ratios when fed a high-forage diet. Calves with divergent RFI
did not have different gross microbial populations as evidenced by the
Firmicute:Bacteriodetes ratio, but low RFI calves tended to have higher fecal Prevotella
spp. and lower fecal Spirochaetes and ruminal Cyanobacteria. The importance of these
subtle shifts in microbial ecology is not evident at this time and more research is needed
to fully elucidate the interaction of host and microbes to fully grasp the importance of
minor microbial deviations. No differences in 3 h MPA were detected in low vs. high
RFI calves but low RFI calves had higher fecal MPA when sampled at 24 h; however,
calculated methane emissions were lower for low RFI calves. Tannin supplementation
had no effect on animal performance and efficiency, ruminal fermentation VFA
concentrations, MPA, or ammonia concentrations in finishing beef steers. There was
also no detrimental effect of tannins on carcass traits; however, hydrolysable tannin
supplementation resulted in increased empty rumen mass. Results from these studies
indicate that diet and nutrient digestibility are affected by RFI such that more efficient
calves had higher DMD, microbial ecology is responsive to RFI such that minor
microbial shifts were observed, and tannin supplementation, at the current inclusion rate,
had no effect on animal and carcass performance.
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Relationships Between Residual Feed Intake and Performance of Heifers of Diverse Breedtypes and Brahman CowsLoyd, Andrea N. 2009 August 1900 (has links)
These studies were designed to evaluate the relationships between residual feed
intake (RFI) and performance of growing heifers and Brahman cows. Residual feed
intake was determined for 77 heifers of diverse breedtypes (Angus, Brahman, Hereford,
Holstein, Jersey and F1 crosses) during both the pre- and post-pubertal periods. Heifers
were individually fed and allowed ad libitum access to feed for 84 +/- 6 d during the prepubertal
feeding trial and 90 +/- 4 d during the post-pubertal feeding trial. Brahmaninfluenced
heifers had lower RFI than heifers without Brahman influence during both
the pre-pubertal (P < 0.05) and post-pubertal (P < 0.0001) periods. Residual feed intake
determined during the pre-pubertal period was only a moderate predictor (r = 0.48; P <
0.0001) of RFI determined during the post-pubertal period.
Residual feed intake was determined for 38 Bonsmara heifers over a 70-d
feeding period. Heifers were fed a high roughage diet at 2.65% of body weight (BW).
Weekly blood serum samples were analyzed for progesterone concentration by
radioimmunoassay (RIA) to determine puberty. There were no observed differences between efficient and inefficient heifers for performance traits, age at puberty or
conception, or cumulative achievement of puberty and conception.
The postpartum performance of Brahman primiparous (n=16) and multiparous
(n=38) cows previously evaluated postweaning for RFI was investigated. Females were
weighed and evaluated for body condition score (BCS) at 28-d intervals prior to the start
of the 2008 calving season. Weekly weights and BCS were collected beginning 21 d
after calving. Blood serum samples were also collected weekly for progesterone
analysis by radioimmunoassay (RIA), non-esterified fatty acid (NEFA) analysis by
enzymatic colorimetry, and insulin-like growth factor-I (IGF-I) analysis by RIA.
Females were exposed to vasectomized marker bulls after calving to aid in estrus
detection. Eight and ten d following observed estrus, females were evaluated using
ultrasonography via rectal palpation to determine the presence of a corpus luteum (CL).
Efficient cows exhibited estrus, developed functional corpora lutea, and exhibited estrus
with CL formation earlier (P < 0.05) than inefficient cows. Furthermore, a greater
percentage (P < 0.05) of efficient than inefficient cows were pregnant at the end of the
breeding season.
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Characterization of Feeding Behavior Traits and Associations with Performance and Feed Efficiency in Finishing Beef CattleMendes, Egleu Diomedes Marinho 2010 August 1900 (has links)
The first objective of this study was to validate the feeding behavior measurements from a radio frequency electronic system (GrowSafe (TM) System Ltd., Airdrie, AB, Canada) and examine the software sensitivity to different parameter settings (MPS) to quantify feeding behavior traits. Data was continuously recorded 24 h per day using the GrowSafe™ system for 32 heifers over 81-d. Ten animals were randomly selected and evaluated over 6-d using time-lapse video recordings. Different parameter settings (MPS) from the electronic system (GrowSafe (TM)) used to record feeding behavior data, bunk visits (BV) frequency and BV duration, were compared with the observed (video) values.
The second objective of this study was to quantify meal criterion; examine the associations between feeding behavior traits, performance, and feed efficiency; and the effects of breed type on feed efficiency (residual feed intake - RFI) and feeding behavior traits in heifers fed high-grain diets.
Results from study one demonstrated that the GrowSafe (TM) system 4000E could accurately predict BV and meal data compared to observed data. The 100 s, used for the maximum duration between consecutive EID recordings to end an uninterrupted BV, was the appropriate MPS to predict BV frequency and duration, and meal frequency and duration compared to observed data using the GrowSafe (TM) 4000E system. The system’s ability to detect the animal’s presence or absence at the feed bunk was 86.4 and 99.6 percent, respectively.
Results from the second study demonstrated that the meal criterion for heifers fed high-grain diets was 13.8 min. The 4 methods to calculate meal criterion demonstrated no differences in results of frequencies and durations of meal and the number of bunk visits per meal. Similar phenotypic correlations were found between the feeding behavior traits with RFI derived from the base model or with adjustments for final back fat. The adjustment of RFI to final back fat changed the RFI rank between breeds. The addition of feeding behavior traits to the RFI base model could accounted up to 40.4 percent of the variation in DMI not explained by ADG or MBW.
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Energy Expenditure in Growing Heifers with Divergent Residual Feed Intake Phenotypes. Effects and Interaction of Metaphylactic Treatment and Temperament on Receiving SteersPaddock, Zachary Dean 2010 August 1900 (has links)
Cattle classified as having low residual feed intake (RFI) phenotypes are those that
consume less feed than expected based on body weight and growth performance. Mechanisms
contributing to the variation in RFI are not fully understood. Previous studies have shown that
cattle of divergent RFI phenotypes have different levels of energy expenditures, which are
associated with heat increment, basal metabolism, thermoregulation responses, and physical
activity. The objectives of this experiment were to characterize residual feed intake (RFI) in
growing heifers and to determine if variation in whole-animal energy expenditure contributes to
differences in RFI. Brangus heifers (n =120) were individually fed a roughage-based diet (1.93
Mcal ME/kg DM) diet twice daily and feed refusals measured weekly. Heifers were weighed
once weekly for 70 d and RFI calculated as the difference between actual and expected DMI from
linear regression of DMI on ADG and mid-test BW0.75. Immediately following the 70 d study,
oxygen pulse rate (mL O2/heart beat) and 48-h heart rates were measured on 8 high and 8 low
RFI heifers to estimate energy expenditure. Daily heart rates and oxygen pulse rates were higher
(P < 0.05) in heifers with high RFI compared to those with low RFI. As a result, energy
expenditure (kcal/BW0.75) was estimated to be 17.4 percent greater (P < 0.05) in high-RFI heifers then
low-RFI heifers.
Mortality and morbidity losses caused by bovine respiratory disease (BRD) continue to
negatively impact the net revenues of the beef cattle industry. Stress can predispose calves
arriving at feedlots to BRD by impairing their immune system with calves having more excitable
temperaments possibly having a greater risk. The objectives of the second study was to examine the effects of metaphylactic treatment and temperament on performance, feed intake, feed
efficiency, and feeding behavior traits in steers. Santa Gertrudis steers (n =119) were weighed
and randomly to control (CON; no antimicrobial treatment) or metaphylactic (MET; 1.5 mL/45
kg BW of ceftiofur crystalline free acid) treatments. Steers were weighed at 14-d intervals and
individual intakes and feeding behavior traits measured using a GrowSafe sytems while fed a
roughage-based diet (2.21 Mcal ME/kg DM). Objective (relative exit velocity; REV) and
subjective (chute score; CS) measurements of temperament were measured on arrival and on day
28 of the study. Steers with higher REV weighed less, grew slower, consumed less feed, spent
less time consuming feeding, had more feeding bouts per meal, had less backfat, smaller
longissimus muscle area, and higher cortisol levels. Steers treated with MET had higher ADG
than those receiving CON. Cattle with higher REV that received MET had less of a decrease in
ADG, DMI, time spend consuming feed, and less of an increase in feeding bouts compared to
high REV steers receiving CON. Results from this study suggest that process-control strategies,
which quantify and manage inter-animal variation in calf temperament may facilitate more
judicious use of antimicrobial products and provide more consistent and predictable responses to
metaphylactic strategies.
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Guaranteed Verification of Finite Element Solutions of Heat ConductionWang, Delin 2011 May 1900 (has links)
This dissertation addresses the accuracy of a-posteriori error estimators for finite element solutions of problems with high orthotropy especially for cases where rather
coarse meshes are used, which are often encountered in engineering computations. We present sample computations which indicate lack of robustness of all standard
residual estimators with respect to high orthotropy. The investigation shows that the main culprit behind the lack of robustness of residual estimators is the coarseness
of the finite element meshes relative to the thickness of the boundary and interface layers in the solution.
With the introduction of an elliptic reconstruction procedure, a new error estimator based on the solution of the elliptic reconstruction problem is invented to
estimate the exact error measured in space-time C-norm for both semi-discrete and fully discrete finite element solutions to linear parabolic problem. For a fully discrete solution, a temporal error estimator is also introduced to evaluate the discretization error in the temporal field. In the meantime, the implicit Neumann subdomain residual estimator for elliptic equations, which involves the solution of the local residual
problem, is combined with the elliptic reconstruction procedure to carry out a posteriori error estimation for the linear parabolic problem. Numerical examples are
presented to illustrate the superconvergence properties in the elliptic reconstruction and the performance of the bounds based on the space-time C-norm.
The results show that in the case of L^2 norm for smooth solution there is no superconvergence in elliptic reconstruction for linear element, and for singular solution the superconvergence does not exist for element of any order while in the case of energy norm the superconvergence always exists in elliptic reconstruction. The research also shows that the performance of the bounds based on space-time C-norm is robust, and in the case of fully discrete finite element solution the bounds for the temporal error are sharp.
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Nonlinear Static and Dynamic Characteristics of Electrostatic Micro-actuatorsChen, Chao-Jung 08 July 2004 (has links)
This dissertation performs a simulation investigation into the nonlinear static and dynamic characteristics of electrostatically driven shaped micro-actuators in micro-electro-mechanical systems (MEMS).
The model proposed in the current nonlinear pull-in deflection study considers various boundary conditions for the electrostatically actuated structures, e.g. the cantilever beam and the fixed-fixed beam, and takes account of the electrical field fringing effect and the axial residual stress. Initially, the Adomian decomposition method is employed to evaluate the response of a micro-actuator incorporating a rectangular micro-beam and a flat electrode by obtaining the closed-form solution of the corresponding nonlinear equation. Since no iteration is required in solving the nonlinear deformation, this decomposition method is one of the most efficient methods available for evaluating the unstable pull-in behavior of an electrostatically driven micro-actuator.
The present study implements both small and large deflection assumptions when simulating the response of the micro-actuator in order to explore the possible effects of the two models on the accuracy of the simulation results. The shaped micro-beam with a curved electrode micro-actuator is further assessed using the differential quadrature method (DQM) to examine the influence of the nonlinear pull-in effect. This dissertation also studies the contact force and the pull-in deflection of shaped micro-tweezers. The DQM is employed to solve the nonlinear interaction between the curved electrostatic field force and the corresponding deflection of the shaped cantilever actuators. The numerical results confirm the ability of the DQM to treat this form of nonlinear actuator problem accurately, efficiently and systematically.
To evaluate the dynamic characteristics of the electrostatic micro-actuator, the DQM is applied to solve the natural frequencies of a fixed-fixed shaped beam vibrating around its statically deflected position under electrostatic loading. The proposed model not only takes account of the nonlinear interaction between the curved electrostatic field force and the restoring force of the shaped micro-beam, but also considers mid-plane stretching, axial residual stress, and electrical field fringing effects. It is shown that an excellent agreement exists between the simulation results obtained using the proposed model and those measured experimentally. This study also investigates the micro-beam and electrode shape effect on the natural frequencies of the actuator system. The analytical results indicate that variations in the shape of the micro-beam or of the electrode not only influence the electrostatic field distribution, but also significantly alter the dynamic characteristics of the micro-actuator. Furthermore, the results demonstrate that the shaped micro-beam with a curved electrode micro-actuator increases the working voltage range of the micro-actuator by a factor of approximately six times compared to that of a micro-actuator incorporating a rectangular micro-beam and a flat electrode.
A continuing trend nowadays is the integration of micro-electro-mechanical devices with electronic circuitry to fabricate MEMS devices such as micro-switches, optical micro-mirrors, etc. It is known that when an electrical voltage is applied to these devices, the micro-actuators will undergo a residual vibration before reaching their permanent position. Hence, this dissertation investigates the residual vibration phenomenon of cantilever beam type micro-switches with air squeeze-film damping between the micro-beam and substrate.
The present simulations of various shaped micro-actuators provide an understanding of the nonlinear static and dynamic behaviors of these devices and as such provide designers with the information required to properly and accurately control the device operating range during the design stage.
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Improvement of Residual Vibrations for Intermittent Positioning TablesLin, Cheng-feng 04 September 2004 (has links)
Recently, many industries pursue the goal of automatic high-speed assembly and manufacturing. So how to meet the requirement of high-precision and high-speed automatic assembly equipment is an important issue. In automatic assembly equipment, the inappropriate acceleration or deceleration motion will cause unsuitable inertia force and vibration to the positioning table. In order to reach the high production efficiency level, the problems of shortage of motor power, poor positioning accuracy, residual vibration, and noise shall be analyzed and solved.
In previous researches, the researchers all devote to study acceleration and deceleration based on symmetrical time chart. In this paper, we change the accelerating and decelerating phase to reduce inertia force and decrease residual vibration of point-to-point motion. The system model is built to simulate dynamic response of the system. Through the results of simulation and experiment, we will discover the relations between the properties of motion and residual vibration about the high-speed positioning tables. It is expected to improve residual vibrations and design motion profiles according to those effective transient response control charts.
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Image Compression Using Wavelet Based Scalable Modeling of Residual ImageLin, Wan-Shan 14 July 2000 (has links)
This thesis is based on the modified JPEG encoding which uses a preprocessing called as Cubic Convolution Spline Interpolation to subsample the original image into lower resolution image, the subsampled image is encoded by JPEG. The modified JPEG can get very high compression ratio, it¡¦s quality is better than the JPEG file which has the same compressing ratio, but it still is not good enough. In this thesis we use the scalable wavelet encoding to encode the residual image, which is the difference between original and compression image. Due to the high compressing ratio and scalablity. We can attach the compressed residual image with modified JPEG compressed image to get the scalable compressed image whose compressing ratio can tun from 125 to 50 and always get better quality than optimal JPEG.
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