Weldability and weld performance of candidate nickel based superalloys for advanced ultrasupercritical fossil power plants Part II: weldability and cross-weld creep performance

Fossil fuel will continue to be the major source of energy for the foreseeable future. To meet the demand for clean and affordable energy, an increase in the operating efficiency of fossil fired power plants is necessary. There are several initiatives worldwide to achieve efficiencies >45%HHV (higher heating value) through an increase in steam temperature (700–760°C) and pressure (27.6–34.5?MPa). Realising this goal requires materials with excellent creep rupture properties and corrosion resistance at elevated temperatures. Two previous papers addressed the welding and weldability of ferritic and austenitic stainless steels. Welding and weldability of nickel based alloys will be discussed in a two-part paper. In this paper, the primary focus will be on the behaviour of candidate nickel based alloys that are being proposed in advanced ultrasupercritical power plants and with regard to weldability (Part I) and cross-weld creep performance (Part II).     

The influence of enantiomorphic transformation on transsaccadic object integration.

Two experiments investigated whether the left–right orientation of an object is retained and integrated across a saccade during object identification. In Experiment 1, participants moved their eyes to the target object and named it as quickly as possible. In Experiment 2, participants looked through an array of 4 target objects in preparation for an immediate recognition test. In both experiments, a peripheral preview of the target object was presented before fixation. The preview stimulus was identical to the target object, the enantiomorph of the target object, or a control stimulus. Naming latencies were faster (Experiment 1) and gaze durations were shorter (Experiment 2) when the preview was identical to the target than when it was an enantiomorph of the target, suggesting that left–right orientation was retained and integrated across saccades. The results constrain models of transsaccadic integration and object identification. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of atmospheric ammonia emissions from a commercial chicken house on the Delmarva Peninsula

A three-dimensional sampling grid using passive collectors was used to characterize the downwind gas-phase ammonia plumes originating from a commercial chicken house on the Delmarva Peninsula in the Chesapeake Bay watershed. Inverse Gaussian plume modeling was used to determine the source strength of the chicken house and the corresponding chicken emission factors. A total of seven field deployments were performed during two different flocks with a sampling duration ranging from 6 to 12.6 h. The deployments occurred during weeks 3, 4, and 5 of the 6-week chicken grow-out period in the months of May-July 2002. The ammonia emission factors ranged from 0.27 to 2.17 g of NH3-N bird(-1) day(-1) with a mean of 1.18 g of NH3-N bird(-1) day(-1). Weighted emissions factors that accounted for the nonlinear increase in ammonia emissions over the 6-week grow-out period were also calculated and ranged from 0.14 to 1.65 g of NH3-N bird(-1) day(-1) with a mean of 0.74 g of NH3-N bird(-1) day(-1). These weighted emission values would correspond to an annual release of approximately 18 x 10(6) kg of NH3-N to the atmosphere from broiler production on the Delmarva Peninsula. This assumes that the emission factors in this study are representative for the entire year with varying meteorological conditions and are representative of all chicken husbandry practices. The Delmarva Peninsula could represent a significant source of nutrient nitrogen to the Chesapeake Bay and Delaware Bay watersheds through atmospheric deposition when considering the size of this annual release rate, the relative short atmospheric lifetime of ammonia due to deposition, and the proximity of the Delmarva Peninsula to the Chesapeake and Delaware Bays.     

Examining the relationship between current attachment status and freely recalled autobiographical memories of childhood.

This study investigated the relationship between individual differences in attachment and the free recall of childhood memories. Specifically, it focuses on how attachment anxiety and attachment avoidance, using the Experiences in Close Relationship Scale self-report, relate to the affective quality and the presence of caregivers in memories from childhood. Participants were 79 undergraduate and masters students attending a northeast university. Participants completed a memory task designed to elicit freely recalled memories from childhood. They then rated the affective valence (positive/negative) and intensity of each memory, and identified memories in which caretakers were present. Attachment avoidance was related to recalling more negative memories involving caretakers and was negatively related to the average intensity of memories involving caretakers. The results support and extend previous research suggesting that affect regulation strategies employed by individuals high in attachment anxiety and high in attachment avoidance are linked to differences in how information about the past is recalled. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructural Characterization of the Heat-Affected Zones in Grade 92 Steel Welds: Double-Pass and Multipass Welds

The microstructure in the heat-affected zone (HAZ) of multipass welds typical of those used in power plants and made from 9 wt pct chromium martensitic Grade 92 steel is complex. Therefore, there is a need for systematic microstructural investigations to define the different regions of the microstructure across the HAZ of Grade 92 steel welds manufactured using the traditional arc welding processes in order to understand possible failure mechanisms after long-term service. In this study, the microstructure in the HAZ of an as-fabricated two-pass bead-on-plate weld on a parent metal of Grade 92 steel has been systematically investigated and compared to a complex, multipass thick section weldment using an extensive range of electron and ion-microscopy-based techniques. A dilatometer has been used to apply controlled thermal cycles to simulate the microstructures in distinctly different regions in a multipass HAZ using sequential thermal cycles. A wide range of microstructural properties in the simulated materials were characterized and compared with the experimental observations from the weld HAZ. It has been found that the microstructure in the HAZ can be categorized by a combination of sequential thermal cycles experienced by the different zones within the complex weld metal, using the terminology developed for these regions based on a simpler, single-pass bead-on-plate weld, categorized as complete transformation, partial transformation, and overtempered.     

Kalirückstandshalde Sollstedt (Thüringen): Untersuchungen zur Ausbreitung der Haldenlösung im Rötkarst

The Sollstedt potash waste pile has been deposited without a basement layer on the Middle Bunter and Roethian. Therefore, a part of the salts dissolved by meteoric water infiltrates into the groundwater. The strongly mineralized waste pile seepage water spreads not only into the Middle Bunter but also into the Roethian, which is generally considered an aquitard, because in this area the Roethian is strongly karstic. This study demonstrates that there is a relationship between the seepage water and the strongly mineralized springs surrounding the stockpile. In particular, the strong mineralization of the Silze spring, which is situated in the supposed direction of groundwater flow, can be attributed to mixing with the seepage water. From the calculated water and salt balances, it is concluded that the major part of the seepage water which previously infiltrated in the Roethian infiltrates directly into the Middle Bunter. This suggests a preferential but locally limited permeability of the Roethian in the horizontal and vertical directions.