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Flash sintering has been shown to be an effective method of sintering for many types of ceramics. However, the characteristics of flash sintering for each type of ceramic varies. When ionically conducting ceramics are sintered under a DC electric field, a strong dependence of densification with respect to position is observed. Microstructural analysis of the effect of electric field on oxygen ion conductors shows non-stoichiometry (oxygen deficiency) at the cathode which continues to build up over time under flash. In oxygen ion conductors, dominant charge carriers during flash are oxygen ions and the final density of the specimen is related to the availability of oxygen. This effect is no longer evident when using an AC power supply. Thus, use of AC instead of DC electric field is preferable for flash sintering of ionically conducting ceramics.

This essay explores the intersection of print, anatomy, and eucharistic language in Robert Burton’s The Anatomy of Melancholy.

Performing cementations in a deepwater environment poses many unique challenges during the drilling and completion operational phases in the Gulf of Mexico. These challenges add further difficulty and risk to an already complex operation. During the course of constructing the wellbore, it may be necessary to perform un-scheduled remedial cementing operations to acheive the main objectives. Squeeze cementing performed to remediate undesireable well conditions which may have resulted during the drilling phase (major mud losses) or as a result of a poor primary cement job (insufficient zonal isolation) must be thoroughly analyzed during planning to understand all the critical parameters needed to execute the right plan. When designing for a squeeze job, key decision factors during the planning process must be addressed for a successful outcome. The success or failure of a squeeze cement operation relies on 1) understanding what is the objective of the squeeze operation 2) determination of the optimum cement placement depth, 3) development of an effective placement procedure with proper technique and down-hole tools employed, 4) proper design of cementing fluids including washes and spacers, 5) flawless execution with a detailed pressure/rate/volume record of fluid injection, and 6) a meaningful post evaluation of the squeeze operation’s results to determine if objective was met. This paper will provide guidance on addressing the key decision factors, development of a proper placement strategy, general design guidelines for appropriate cementing fluids to employ, and how to evaluate if the objective was met. Results will be presented from recent deepwater case histories to demonstrate the successful application of this methodology for squeeze jobs and the techniques used.

A multitude of challenges exist when cementing production liners for deepwater operations. In many platform operations, cutting windows to sidetrack and drill highly deviated well paths to intersect reservoir targets result in difficulty obtaining adequate casing standoff due to tight inside diameter (ID) restrictions from previous casing architecture. Many of the zones near the target interval may have significant pressure depletion which can lead to expensive Synthetic Based Mud (SBM) losses and associated non-productive time (NPT). The size of the production liner is dependent on the wellbore architecture and completion plan. Thus in most cases, the borehole must be under-reamed in order to provide for adequate cement sheath thickness. In these cases, centralizer selection and placement can be challenging or all together impractical. Cementing in SBM environments has also been traditionally more challenging because special considerations for spacer/surfactant/mud design and testing are required to effectively displace the mud and "water-wet" the formation/casing for good quality cement-bonding. Technology improvements in spacer and surfactant package formulations provide a more qualitative method for optimum surfactant design to maximize mud removal and provide a bonding surface to the formation. Liner hanger selection may not always provide the capability for pipe rotation which has shown to be very effective for mud removal and increased circumferential cement coverage. Without pipe rotation, additional key techniques for successful cementation must be prioritized. A process driven decision matrix is presented along with a recent selection of successful production liners to support the design concept.

Charles Garnier's Paris Opéra (1861-75) and Baron Haussmann's contemporary replanning of Paris (1853-70) supposedly represent the Second Empire of Napoléon III. But this case study of the Opéra within the context of its quarter of Paris contradicts the usual assumptions that the monument and the city were either the inevitable products or the characteristic political expressions of the state. First, a chain of events dating back to the seventeenth century is reconstructed in order to demonstrate that the decision reached in 1860 to site the Opéra on the Grands Boulevards at the end of a projected new avenue was less the consequence of an imperial plan than the pragmatic result of the often contingent urban history of Paris. Second, the parallel and equally pragmatic evolution of the characteristic Parisian façade of a giant order on an arcuated base is traced from the seventeenth to the nineteenth centuries in order to explain why Garnier's Opéra and Haussmann's surrounding buildings came to have the same form of elevation. Interpreted in light of both the Opéra's own ambiguous status as a state institution and the ambiguous nature of nineteenth-century bourgeois civil society, this evidence suggests that neither urban nor architectural forms are fixed in their meaning, but tend rather to adjust their meaning to the changing circumstances of their use. This article concludes that a city and its monuments find their meaning in the continuous process by which a city's inhabitants shape and experience their surroundings, rather than in the episodic political programs of the state.