Browsing Retrospective Theses and Dissertations (1922-2004) by Title

0-g annular flow and 1-g stratified flow single component two-phase condensation modeling and experiments

Baranek, Pascale (Texas A&M University, 1993)

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The 1993 nutrition label: development of a rating system and a perspective by nutrition and food industry professionals

Osborn, Lacye Ann (Texas A&M University, 1994)

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Abstract:	The objectives of this study were to develop a nutrition scoring system which would combine the nutritional information on the new label into a single number, to identify strengths and weaknesses of the new nutritional labels according to nutrition and food industry professionals and to determine if any differences exist between professionals' perception of the nutritional label. A scoring system was designed using the components on the new nutritional label. Labels from main dish products were used for scoring. Each component was given points of 0, 25, 50, 75 or 100 according to the amount present. A score was assigned based on an average of the points. When incorporated with the existing label, the scoring system could be very useful to consumers while still providing specific information for individuals. By making the label easier to understand, it would add to the consumer's willingness to use the label. A questionnaire to assess attitudes toward each component on the new nutritional label was sent to members of the American Dietetic Association (ADA, n--1220)andthelnstituteofFoodTechnologists(IFT,n--441). Atotalof464 professionals (28%) responded of which 79% and 22% were ADA and IFT members, respectively. Responses varied with subject age, position, job function and area of practice or responsibility. With the exception of protein, ADA respondents considered each component of the label to be more important than did I]FT respondents. Both groups ranked kilocalories (kcal), total fat, and sodium to be more important components and vitamin A and C and sugars less important. ADA respondents indicated that percentage kcal from fat and other vitamins and minerals should be added to the label. IFT respondents were concerned with the process and the costs required to modify the labels. In conclusion, the nutritional components on the new label were acceptable to this sample of the population. The observation that differences of opinions within the groups of professionals were not as widespread as expected is important. The less variation seen within the parties involved in label policy, the easier it should be to produce nutrition messages which consumers will understand.
Description:	Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item. Includes bibliographical references.
URI:	http://hdl.handle.net/1969.1/ETD-TAMU-1994-THESIS-O813

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The 1994 Net Ban Constitutional Amendment: a case study of marine fisheries management in Florida

Grimes, Shepherd Russell (Texas A&M University, 1996)

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Abstract:	On November 8, 1994 the Florida electorate voted 2,876,091 to 1,135,110 in favor of proposed amendment #3 to the state constitution. The amendment effectively reallocated the state's nearshore fisheries to predominantly recreational "hook and line" anglers through a ban on the use of certain net gear. The amendment was initiated via a petition drive supported by a coalition of recreational fishing and conservation groups. These interest groups have continued to play an increasingly important role in the management of Florida's marine fisheries resources. This thesis presents a case study of the issues and events leading to the electoral approval of Article X, Section 16 of the Florida Constitution. An in-depth look at the case is presented, highlighting critical issues and occurrences. Also, theoretical explanations for case findings are presented. The vigor of related interest groups was the key to the initiation and success of the referendum. For years, well-organized groups representing the commercial industry maintained a considerable presence and influence in state government. Focusing much of their efforts on the Governor and Cabinet, and pursuing rule challenges, these groups prevented the implementation of numerous regulations supported by recreational interests. After limited success through institutional channels, recreational interests formed a coalition and initiated a petition drive that succeeded in getting the proposed amendment on the ballot. The established institutions responsible for marine fisheries management in Florida failed to appreciate the strength of organized recreational fishing interests within the state. Although its inability to sufficiently address the issue was partially attributable to the institutional hierarchy, the Florida Marine Fisheries Commission must better appreciate the role of such interest groups.
Description:	Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item. Includes bibliographical references: p. 101-109. Issued also on microfiche from Lange Micrographics.
URI:	http://hdl.handle.net/1969.1/ETD-TAMU-1996-THESIS-G76

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1996 Thesis G76.pdf (3.374Mb)

20 MHz IF bandpass switched capacitor [] modulator using a high performance OTA with NCFF compensation scheme

Thandri, Bharath Kumar (Texas A&M University, 2001)

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Abstract:	Switched capacitor (SC) circuits are widely used in many applications because of their accuracy and ease of integration in CMOS technology. They are not suitable for operation in high frequencies because of the settling time limitation of amplifiers. High frequency switched capacitor circuits pose challenging design specifications on the amplifiers which cannot be met by conventional circuit design techniques. High amplifier gain is required for an accurate output, whereas fast settling time is obtained by a high gainbandwidth (GBW) product. Amplifiers that use cascading of gain stages for obtaining high gain require some robust frequency compensation schemes, and usually have a low GBW, resulting in a slow settling time. This work proposes a new compensation scheme for high gain wideband amplifiers - No Capacitor Feed Forward (NCFF) compensation scheme. NCFF scheme uses pole-zero cancellation to obtain high gain, high GBW and a good phase margin. Left half plane (LHP) zeros produced due to the feedforward path causes a positive phase shift and is used to cancel the negative phase shift of poles. Fully differential and single ended operational transconductance amplifiers (OTA) using the proposed NCFF compensation scheme have been designed and fabricated using CMOS AMI 0.5 []m technology. The fully differential OTA has a gain of 97 dB, GBW of 350 MHz and a phase margin of around 90°. Sigma delta [ ] modulators use oversampling and quantization noise shaping to obtain a high dynamic range. They are well suited for use in radio and cellular systems to directly convert the narrowband IF signal centered at high frequencies to digital domain. Switched capacitor implementation of a [ ] modulator requires a fast settling amplifier to operate at high IF frequencies. The design and implementation issues of a 20 MHz IF, 80 MHz clock, fourth order switched capacitor bandpass [ ] modulator are discussed in detail. The modulator uses a high performance OTA using the proposed NCFF compensation scheme and it has been designed and fabricated using 3.3V CMOS TSMC 0.35 []m technology. The bandpass [ ] modulator has a peak SNR of 70 dB (post-layout simulations).
Description:	Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item. Includes bibliographical references (leaves 91-93). Issued also on microfiche from Lange Micrographics.
URI:	http://hdl.handle.net/1969.1/ETD-TAMU-2001-THESIS-T424

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2001 Thesis T424.pdf (2.325Mb)

2-D discrete element modeling of unconsolidated sandstones

Franquet Barbara, Javier Alejandro (Texas A&M University, 2001)

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Abstract:	In this work unconsolidated sands saturated with heavy oil were modeled using a discrete element numerical model, (DEM). The DEM code was built in Mathematica ♭ programming language. The strain-stress behavior of biaxial tests using the code developed in this thesis is compared to the results of triaxial tests performed in cylindrical core samples of unconsolidated sandstones saturated with heavy oil. The discrete element model treats the sand as a two dimensional assembly of particles. The displacements and velocities of each particle are calculated in order to determine local rearrangements during deformation. The kinematics of the system is performed in small time steps where force and torque balance is calculated for each disk. Several grain forces are simulated in this DEM model when the unconsolidated sand, saturated with heavy oil, is under a deviatoric loading condition. The contact forces are modeled as spring and dashpot forces, and they are applied in the contact point in the normal and tangential directions. Friction viscous forces are included for linear displacements and for rotational movements. The viscous forces generated by the movements of very close neighborhood particles are also considered in the model. The DEM code is also capable of modeling capillary forces between grains when the assembly is considered partially saturated, and the interstitial liquid is filling the porous space as a discrete liquid bridge between particles. Four boundary walls surround the particle assembly. The bottom boundary is considered flat, frictionless, and static while the top boundary is a stress controlled wall. The other two vertical boundaries are under a confining distributive force, and these walls can be modeled as two parallel flexible boundaries or as a simple horizontal force condition distributed to the boundary particles. Compressibility and apparent Young's modulus are compared between the DEM results and the laboratory geomechanical data. This investigation is part of ongoing research to obtain the micro-mechanical parameters needed for future hydraulic fracture propagation studies in an unconsolidated formation impregnated with heavy oil.
Description:	Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item. Includes bibliographical references (leaves 117-125). Issued also on microfiche from Lange Micrographics.
URI:	http://hdl.handle.net/1969.1/ETD-TAMU-2001-THESIS-F68

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2001 Thesis F68.pdf (4.653Mb)

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Abstract:	A 3-D laser doppler velocimeter was used to measure the flow field inside a whirling annular and labyrinth seal. The data was collected and phase averaged with the seals operating at a Reynolds number of 24,000 and a Taylor number of 6,600. The annular seal has an outside diameter of 164 mm, is 37.3 mm long and has a clearance of 1.27 mm. The labyrinth seal was of a straight through design with seven cavities. The seal has an outer diameter of 164 mm, is 33.5 mm long and has a clearance of 1.27 mm. The eccentricity ratios of the annular and labyrinth seals were 0.10 and 0.50 respectively. The whirl ratio for both seals were 1.00. For both seals the maximum axial velocity is not located at the maximum clearance over the length of the seals as would be expected. Instead the maximum a)axial velocities are seen on the pressure side of the seals at the inlet but migrates to the suction side of the seal at the exit. The magnitude of this migration is dependent upon the seal eccentricity. The labyrinth seal exhibits an axial recirculation zone at the seal inlet due to its larger eccentricity. The radial velocity profiles are generally dependent on the seal eccentricity as well. Tangential velocities are seen to develop in inverse proportion to the axial velocity. For the annular seal the flow exhibits an uniform tangential velocity distribution by a location of ZAL = 0.10. The labyrinth seal displays a similarly uniform distribution for the tangential component by the third cavity(Z/L = 0.36). The exit magnitudes of the azimuthal velocity is about 0.4WSh indicating that the azimuthal velocity is not significantly altered by altering the whirl ratio. Turbulence generation is dominant over the first third of the seal after which there is a sharp decrease in the turbulence levels.
Description:	Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item. Includes bibliographical references.
URI:	http://hdl.handle.net/1969.1/ETD-TAMU-1993-THESIS-D229

Abstract:	Orifice meters are used for the measurement of flow rate, particularly in the natural gas industry. They are relatively simple and inexpensive devices; the flow rate is calculated by observing the pressure drop across an orifice plate. Uncertainty of metering accuracy has resulted in an estimated tens of millions of dollars of annual mischarges for gas companies. This has led to basic research on methods to improve orifice meter accuracy. Those investigations underline the importance of the upstream velocity profile effects upon the orifice plate discharge coefficients Cd- Changes in q are undesirable because they cause inaccuracies in flow measurement. This study was undertaken to determine the effect of the upstream velocity profile upon the flow field inside a standard orifice flowmeter. A 3-D LDV (Laser Doppler Velocimeter) was used to obtain detailed velocity and turbulence measurements for a flow of air in an orifice meter (P=0.5) at a Reynolds number of 91,100 with three different inlet velocity profiles. Analysis of the correlated, instantaneous velocities in three dimensions enabled calculation of the mean velocity components, the complete Reynolds stress tensor for compressible flow: [], the triple correlations, the rate of turbulence production, vorticity, and turbulent kinetic energy. In addition, particularities of such a turbulent flow were determined: the point of reattachment, the downstream primary recirculation zone and the upstream recirculation zone, the axial location of maximum velocity (vena contracta).
Description:	Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item. Includes bibliographical references. Issued also on microfiche from Lange Micrographics.
URI:	http://hdl.handle.net/1969.1/ETD-TAMU-1995-THESIS-R624