Geotextile and geogrid reinforcement in flexible pavements were evaluated to determine potential benefits. Laboratory pavement sections were constructed, tested, and analyzed to assess the performance of reinforced pavement sections compared to sections without geosynthetic reinforcement. The pavement sections were designed to model a typical low-volume traffic secondary road built over a weak subgrade. The tests sections were constructed using different base course thicknesses and different subgrade CBR values. The pavements were dynamically loaded at a frequency of 0.5 Hz using a computer controlled pneumatic loading system. A force of approximately 9000 lbs (40 kN) was applied to the pavement through a rigid plate. This system modeled the dual tire load from an 18 kip (80 kN) truck axle. Surface deflections were measured during loading using an L VDT array. The performance of the pavement sections was assessed based on AASHTO and linear viscoelastic design procedures. A service-life-cost criterion was used to compare the performance of the test sections. / M.S.

No / The paper examines the determinants of stabilization and its impact on the aftermarket prices. We use a unique dataset to relax several assumptions in the stabilization literature. We find that underwriters support IPO prices shortly after listing, particularly in cold markets and when demand is weak. We also show that stabilized IPOs are more common amongst reputable underwriters. This finding suggests that stabilization may be used as a mechanism to protect the underwriter’s reputation. It also implies that reputable underwriters may possess private information and price IPOs closer to their true values (i.e., higher than those indicated by the weak premarket demand). Consistent with the latter view, we show that stabilized IPOs are offered at higher prices and suffer less underpricing than those indicated by the premarket demand, firm characteristics and market-wide conditions. The post-IPO performance results indicate that stabilized IPOs are unlikely to be mispriced as their prices do not exhibit any significant reversal after the initial stabilization period. We conclude that stabilization may be superior to underpricing as it protects investors from purchasing overpriced IPOs, benefits issuers by reducing the total money “left on the table” and enhances the overall profitability of underwriters.

Yes / A simulation was conducted using Aspen HYSYS® software for an industrial scale condensate stabilization unit and the results of the product composition from the simulation were compared with the plant data. The results were also compared to the results obtained using PRO/II software. The results show that the simulation is in good agreement with the plant data, especially for medium range hydrocarbons. For hydrocarbons lighter than C5, the simulation results over predict the plant data while for hydrocarbons heavier than C9 this trend is reversed. The influences of steam temperature and pressure, as well as feed conditions (flow rate, temperature and pressure) for the product specification (RVP and sulphur content) were also investigated. It was reported that the operating conditions gave rise to the production of off-specification condensate and it was also found that the unit could be utilized within 40–110% of its normal throughput without altering equipment sizing and by the operating parameters.

We apply the Segal process of group simplification to the linear harmonic oscillator. The result is a finite quantum theory with three quantum constants instead of the usual one. We compare the classical (CLHO), quantum (QLHO), and finite (FLHO) linear harmonic oscillators and their canonical or unitary groups. The FLHO is isomorphic to a dipole rotator with N=l(l+1) states where l is very large for physically interesting case. The position and momentum variables are quantized with uniform finite spectra. For fixed quantum constants and large N there are three broad classes of FLHO: soft, medium, and hard corresponding respectively to cases where ratio of the of potential energy to kinetic energy in the Hamiltonian is very small, almost equal to one, or very large The field oscillators responsible for infra-red and ultraviolet divergences are soft and hard respectively. Medium oscillators approximate the QLHO. Their low-lying states have nearly the same zero-point energy and level spacing as the QLHO, and nearly obeying the Heisenberg uncertainty principle and the equipartition principle. The corresponding rotators are nearly polarized along the z-axis. The soft and hard FLHO's have infinitesimal 0-point energy and grossly violate equipartition and the Heisenberg uncertainty principle. They do not resemble the QLHO at all. Their low-lying energy states correspond to rotators polaroizd along x-axis or y-axis respectively. Soft oscillators have frozen momentum, because their maximum potential energy is too small to produce one quantum of momentum. Hard oscillators have frozen position, because their maximum kinetic energy is too small to produce one quantum of momentum. Hard oscillators have frozen position, because their maximum kinetic energy is too small to excite one quantum of position.

Martensite-to-Beta transformation temperatures of CuAlNiMn and CuAlNi shape memory alloys has been determined by differential scanning calorimetry (DSC). In CuAlNiMn alloys, each new betatizing treatment has resulted in randomly varying transformation temperatures on the same specimen and an anomalously diffuse and serrated Martensite-to-Beta transformation peaks in the first cycle. Therefore, as quenched alloy samples were thermally cycled for three times in DSC prior to ageing to obtain thermally stable and reproducible transformation temperatures and to eliminate the anomalous effect of betatizing on the transformation temperatures. CuAlNiMn alloys were aged in martensitic condition at temperatures in the range 80&amp / #61616 / C to 150&amp / #61616 / C for 24 hours to 312 hours ageing periods. Both A_s and A_f temperatures have increased with ageing temperature and time while M_s and M_f temperatures have not changed during martensite ageing. Transformation temperatures of CuAlNi alloys, on the other hand, have not changed during martensite ageing. In this respect, CuAlNiMn alloys were found to be more prone to martensite stabilization than the CuAlNi alloys. Through Transmission Electron Microscope investigation in the Cu-12.6wt%Al-5.9wt%Ni-1.8wt%Mn alloy aged at 150&amp / #61616 / C for 312 hours has revealed no sign of precipitate formation and it has been concluded that the &amp / #65533 / precipitates pinning martensite boundaries&amp / #65533 / mechanism could not be responsible of martensite stabilization. Beta phase ageing of CuAlNiMn alloys at temperatures 200&amp / #61616 / C, 230&amp / #61616 / C, 250&amp / #61616 / C and 270&amp / #61616 / C, have drastically shortened the periods for stabilization to the extent that &amp / #946 / -to-M transformation completely ceases. With regard to the Manganese content, highest Manganese bearing alloy was the one stabilized first and the lowest manganese containing one was the longest lasting alloy during beta phase ageing. Beta stabilization was not observed in any of the four CuAlNi alloys at the end of 96 hours ageing at 200&amp / #61616 / C while beta stabilization was realized after 26, 38 and 11 hours ageing at the same temperature in the three Mn containing alloys studied. In conclusion, on the basis of ageing studies at 200&amp / #61616 / C, with regard to beta stabilization, CuAlNi alloys were found to be more resistant to high temperature ageing than CuAlNiMn alloys. Equilibrium &amp / #947 / _2 and &amp / #945 / phases were observed with coupled-grown lamellar morphologies in Cu-13.6%Al-3.0%Ni alloy aged above 400&amp / #61616 / C.

Thesis (M. Phil.)--University of Hong Kong, 1993.

Thesis (M.Phil.)--University of Hong Kong, 1993. / Also available in print.

Ces travaux sur la stabilisation de la Ligne de Visée d’un dispositif optronique s’inscrivent dans le contexte actuel de durcissement des exigences de stabilisation et de réduction du temps accordé à la synthèse des lois de commande.Ils incluent dans un premier temps l’amélioration de la performance intrinsèque de stabilisation du système. La solution proposée ici est l’ajout d’un étage de stabilisation supplémentaire à une structure de stabilisation existante. L’architecture de ce nouvel étage est définie. Les composants sont choisis parmi les technologies existantes puis caractérisés expérimentalement. Un modèle complet du système à deux étages de stabilisation est ensuite proposé.L’objectif de ces travaux comprend également la simplification des procédures d’élaboration des lois de commande par l’utilisation d’une fonction de coût F incluant notamment la Fonction de Transfert de Modulation (qui quantifie le flou introduit par l’erreur de stabilisation dans l’image) en lieu et place ducritère dérivé usuel qui nécessite des vérifications supplémentaires et qui peut s’avérer conservatif.L’évaluation de F étant coûteuse en temps de calcul, un algorithme d’optimisation bayésienne, adapté à l’optimisation des fonctions coûteuses, permet la synthèse des lois de commande du système dans un temps compatible avec les contraintes industrielles, à partir de la modélisation du système précédemment proposée. / The presented work on the Line of Sight stabilization of an optronic device meets the heightened demands regarding stabilization performances that come with the reduction of the time allowed to controller tuning.It includes the intrinsinc improvement of the system stabilization. The proposed solution features a double stabilization stage built from a single stabilization stage existing system. The new architecture is specified and the new components are chosen among the existing technology and experimentally characterized. A complete double stabilization stage model is then proposed.The simplification of the controller tuning process is another goal. The designed cost function F includes a high-level optronic criterion, the Modulation Transfer Function (that quantifies the level of blur broughtinto the image by the residual motion of the platform) instead of the usual low-level and potentially conservative criterion.The function F is costly to evaluate. In order to tune the controller parameters within industrial time constraints, a Bayesian algorithm, adapted to optimization with a reduced budget of evaluations, is implemented.Controllers of both stabilization stages are simultaneously tuned thanks to the previously developped system model.

Thesis (Ph.D.)--RAND Graduate School, 2007. / Includes bibliographical references.

Rammed earth is a monolithic construction formed by compacting processed soil in progressive layers. Rammed earth is used for the construction of load bearing walls, floors, sub base material in roadways, airport runways, taxiways, aprons, foundations and earthen bunds. Soil, sand, cement and water are the ingredients used for the preparation of cement stabilized rammed earth (CSRE) specimens. The cracking in a rammed earth structure is due to the development of tensile stresses. The tensile stresses are generated due to various causes like unequal settlement of foundation, eccentric loading and / or lateral loading such as wind pressure and earthquake on an earth structure. The cracking in a rammed earth structure causes the failure of its intended function. For example formation of crack may lead to the instability of an embankment slope. And earthen dam can be destroyed gradually by erosion of soil at the crack surface (Harison et al. 1994). Hence, it becomes important to understand the fracture behaviour of cement-stabilized rammed earth structures. Well focused studies in understanding the fracture behaviour of CSRE structures are scanty. The present work attempts to address some issues on the fracture behaviour of CSRE including size effect. Through an experimental programme material properties viz. compressive strength, tensile strength and stress-strain relationships are generated for two chosen densities, 17 and 18.5 kN/m3 of CSRE both in dry and saturated condition. Soil composition, density, cement content and moisture content of the specimen during testing influence the characteristics of CSRE. In the present investigation keeping the cement at 10%, the density is varied choosing a soil-sand mixture having optimum grading limits. The basic raw materials used are soil, sand, cement and water in the ratio of 1 : 1.5 : 0.25 : 0.34 by weight. The strength properties studied alone are inadequate to predict the mechanics of fracture due to the presence of microscopic flaws, cracks, voids and other discontinuities. Therefore, some linear elastic fracture parameters such as mode I fracture toughness (KIc), critical energy release rate (GIc), net section strength (f net) and notch sensitivity are calculated, presuming that CSRE is still a brittle material because it is yet to be confirmed that CSRE is a quasibrittle material. In fact, in the present work, it is shown that CSRE has significant amount of softening. A comprehensive experimental work has been undertaken to test CSRE beam specimens for two densities, three sizes of beam and three notch to depth ratios under three point bending (TPB) in a closed loop servo-controlled machine with crack mouth opening displacement control. Results indicate that the CSRE in dry condition exhibits a greater resistance to fracture than the saturated specimen. The variation of net section strength with the notch depth is not significant. Therefore the CSRE material is notch insensitive, implying that it is less brittle. An experimental program was undertaken to determine the nonlinear fracture parameters of beam specimens both in dry and saturated condition. The influence of moisture content, density, size of the specimen as well as notch to depth ratio of the specimen on RILEM fracture energy (G F ) are presented. The GF values increase with increase in density and size of the specimen, while they decrease with increase in notch to depth ratio. Results clearly show that the total energy absorbed by the beams (W OF ) and RILEM fracture energy (G F ) for all specimens tested in dry state are higher compared to the specimens tested in saturated state, indicating that the dry specimen offers higher resistance to the crack propagation. The RILEM fracture energy GF , determined from TPB tests, is said to be size dependent. The assumption made in the work of fracture is that the total strain energy is utilized for the fracture of the specimen. The fracture energy is proportional to the size of the fracture process zone (FPZ), which also implies that size of FPZ increases with increase in the un-cracked ligament (d - a) of beam. This also means that FPZ is proportional to the depth d for a given notch to depth ratio, because for a given notch/depth, (d - a) which is also is proportional to d because is a constant. This corroborates the fact that fracture energy increases with size. Interestingly, the same conclusion has been drawn by Karihaloo et al. (2006). They have plotted a curve relating fracture process zone length and overall depth the beam. In the present study a new method namely Fracture energy release rate method proposed by Muralidhara et al. (2013) is used. In the new method the plot of GF /(d - a) versus (d - a) is obtained from a set of experimental results. The plot is found to follow power law and showed almost constant value of GF /(d - a) at larger ligament lengths. This means the fracture energy reaches a constant value at large ligament lengths reaffirming that the fracture energy from very large specimen is size-independent. This Fracture energy release rate method is used to determine size-independent fracture energy GRf , based on the relationship between RILEM fracture energy and the un-cracked ligament length. The experimental results from the present work agree well with the proposed new method. Similarly, the method is extended to determine nominal shear strength τv for large size beam. Results show that for both densities GRf decrease in saturated condition, while in dry condition as the density is increased from 17 to 18.5 kN/m3 the GRf decrease by 7.58%, indicating that the brittleness increases with higher density. The τv for large size beam increases with density both in dry and saturated condition. The size effect method for evaluating material fracture properties proposed by Bazant (1984) is applied to cement stabilised rammed earth. By measuring the peak loads of 2D geometrically similar notched beam specimens of different sizes, nonlinear fracture parameters such as fracture energy (Gf ), fracture toughness (KIc), effective length of the fracture process zone (Cf ), brittleness number (β), characteristic length (l 0) and the critical crack tip opening displacement (CT ODc) are determined for both dry and saturated conditions. The crack growth resistance curves (R-curve) are also developed for dry and saturated specimens. In the size effect method, for both densities 18.5 and 17 kN/m3 the values of nonlinear fracture properties, namely G f , Cf , KIc, CT ODc and l 0 are lower for the saturated specimen compared to those of the dry specimen. In dry condition as the density is increased from 17 to 18.5 kN/m3 the Gf decreases to 13.54%, indicating that the brittleness increase with higher density. The areas under the load-displacement and load-CMOD curves are a measure of the fracture energy and these areas are low for saturated specimens. The crack growth resistance curves (R-curve) plotted using the size-effect law from peak loads are the measure of resistance against crack growth R. The value of R is high for dry specimen compared to that of the saturated specimens. During aggregate pullout or the opening of crack, the interlock or friction between the crack surfaces may cause the energy dissipation through friction and bridging across the crack. Therefore the wet friction in case of saturated specimen must be smaller resulting in more brittleness compared to the larger dry friction for dry specimen. In the present investigation the Digital Image Correlation (DIC) technique is used to study the FPZ properties in cement stabilised rammed earth. The MATLAB package written by Eberl et al. (2006) is suitably modified and used for image correlation to suit our requirements. CMOD measured using DIC technique is validated by comparison with the CMOD measured using clip gauge. The FPZ properties such as the development of FPZ and crack opening displacements at different loading points as well as the influence of notch/depth ratio on FPZ length (lFPZ ) are evaluated for both dry and saturated conditions. At peak load the lFPZ are about 0.315 and 0.137 times the un-cracked ligament length respectively for specimens tested under dry and saturated conditions. In dry and saturated states the FPZ length decreases as the ratio increases. Lower values of lFPZ in saturated specimen indicates that it is relatively more brittle compared to dry specimen.