Stochastic unit commitment problem

The electric power industry is undergoing restructuring and deregulation. We need to incorporate the uncertainty of electric power demand or power generators into the unit commitment problem. The unit commitment problem is to determine the schedule of power generating units and the generating level of each unit. The objective is to minimize the operational cost which is given by the sum of the fuel cost and the start‐up cost. In this paper we propose a new algorithm for the stochastic unit commitment problem which is based on column generation approach. The algorithm continues adding schedules from the dual solution of the restricted linear master program until the algorithm cannot generate new schedules. The schedule generation problem is solved by the calculation of dynamic programming on the scenario tree.     

Automation of cytokine flow cytometry assays

Cytokine flow cytometry (CFC) is a multiparameter assay of antigen-specific T cell function, potentially useful in the monitoring of experimental vaccines and progression of infectious diseases and cancer. Automation of CFC assays would greatly facilitate their use in clinical trials and involves several components. We describe here the migration of these assays to 96-well plates, the use of sample-handling robotics, and the use of lyophilized antigen and antibody plates to help automate CFC. Together, these elements can produce an integrated system capable of walkaway automation of an entire assay, resulting in the reproducible processing of potentially hundreds of samples per day. Implementation of such systems has begun to be undertaken by our group and others.     

Pancake Vortices

I describe the magnetic-field and current-density distributions generated by two-dimensional (2D) pancake vortices in infinite, semi-infinite, and finite-thickness stacks of Josephson-decoupled superconducting layers. Arrays of such vortices have been used to model the magnetic structure in highly anisotropic layered cuprate high-temperature superconductors. I show how the electromagnetic forces between pancake vortices can be calculatated, and I briefly discuss the effects of interlayer Josephson coupling.     

Design and testing of the Minotaur advanced grid-stiffened fairing

A composite grid-stiffened structure concept was selected for the payload fairing of the Minotaur launch vehicle. Compared to sandwich structures, this concept has an advantage of smaller manufacturing costs and lighter weight. To reduce weight the skin pockets are allowed to buckle visibly up to about 0.5 cm peak displacement.

Various failure modes were examined for the composite grid-stiffened structure. The controlling criterion for this design was a joint failure in tension between the ribs and skin of the structure. The identification of this failure mechanism and the assessment of bounding strains required to control it required extensive test and analysis effort. Increasing skin thickness to control skin buckling resulted in reduced strains between the skin and ribs.

Following the identification of the relevant failure criteria, a final design for the fairing was generated. The resulting 6 m tall fairing was constructed of a tow-placed carbon fiber composite grid structure that was over-wrapped to create a laminated skin. Upon completion of curing and machining, the fairing was cut in half to create the classic “clam-shell” fairing. Static qualification testing demonstrated the structural integrity of the fairing, thereby proving the design and manufacturing process. Loads were applied incrementally in a static loading scenario. The applied load envelope exceeded worst-case dynamic flight conditions with an added safety factor of 25%. At peak load the fairing maintained structural integrity while remaining within the required displacement envelope for payload safety.

Data were collected during the test from a variety of sensors including traditional displacement transducers and strain gages. In addition, full field displacement was monitored at critically loaded fairing sections by means of digital photogrammetry. This paper summarizes the test results, presents the overall performance of the fairing under the test loads, correlates test response and analysis, and identifies lessons learned.

Work continues at the Air Force Research Laboratory (AFRL) and Boeing to identify means of further controlling tensile failure of the un-reinforced polymer bonded joint between the ribs and skin. Stiffening of skin adjacent to the joints and introduction of lightweight foam jackets at the interior of the fairing both show promise of delaying joint failure to higher loads.     

Using Taxometric Analysis to Distinguish a Small Latent Taxon From a Latent Dimension With Positively Skewed Indicators: The Case of Involuntary Defeat Syndrome.

Joining the debate on the structure of depression, S. R. H. Bearh and N. Amir (2003) analyzed college students' responses to 6 Beck Depression Inventory (BDI) items with predominantly somatic content and concluded that they identified a small latent taxon corresponding to involuntary defeat syndrome. An exact replication of these analyses yielded virtually identical taxometric results, but parallel analyses of simulated taxonic and dimensional comparison data matching the intercorrelations and skewed distributions of the BDI items showed the results to be more consistent with dimensional than with taxonic latent structure. Analyses in a clinical sample with nonskewed indicators further supported a dimensional interpretation. The authors discuss methodological strategies for conducting and interpreting taxometric analyses under the adverse conditions commonly encountered in psychopathology research, including skewed indicators and small putative taxa. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Placebo Psychotherapies and Nonconscious Learning in the Placebo Effect: Reply to Kirsch (2004).

In this reply, the authors explore several issues raised by I. Kirsch (2004; see record 2004-11156-008) concerning their original article (S. Stewart-Williams & J. Podd, 2004; see record 2004-11156-007), which dealt with the roles of expectancy and classical conditioning in the placebo effect. The only notable disagreement concerns a definitional issue, namely, Stewart-Williams and Podd's claim that the placebo concept can be extended to inert psychotherapies. The authors defend this claim against the criticisms Kirsch raised. In addition, they comment on the suggestion that nonconscious learning processes play only a small role in human placebo effects, arguing that there are theoretical reasons to expect these processes to be more important than has previously been recognized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beyond the "Self in Self-Efficacy: Spouse Confidence Predicts Patient Survival Following Heart Failure.

Ratings of patient efficacy to manage illness, made by 191 congestive heart failure patients and their spouses, were examined as predictors of patients' survival over the next 4 years. When considered alone, both the patient's self-efficacy and the spouse's confidence ratings predicted survival, but only spouse confidence remained significant when both partners" efficacy ratings were included in the same Cox regression model. The overlapping prognostic significance of spouse confidence and a global, multicomponent measure of marital quality positioned the former as a proxy for the latter, reflecting a fundamentally social protective factor in patient survival. Successful adaptation to heart failure appears to involve more than the patient's personal agency, and psychosocial data from spouses can improve prediction of patient outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interparental Conflict and Adolescent Dating Relationships: Integrating Cognitive, Emotional, and Peer Influences.

This study investigated the ways in which exposure to interparental conflict may affect adolescent dating relationships in a sample of 391 adolescents ages 14 to 18 years. Boys exposed to greater parental discord were more likely to view aggression as justifiable in a romantic relationship, had more difficulty managing anger, and believed that aggressive behavior was more common in their peers' dating relationships. Each of these variables in turn linked witnessing interparental conflict to higher levels of verbal and physical aggression toward their own romantic partners. Interparental conflict was not related to girls' aggressive behavior. These data support the value of targeting cognitive and emotional processes in prevention programs designed to reduce dating violence and suggest that such programs will be strengthened by focusing on peer influences as well. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychological Response to Test Results in an Ovarian Cancer Screening Program: A Prospective, Longitudinal Study.

To identify the psychological impact of receipt of an abnormal yet benign screening test result, the authors examined the response to a transvaginal ultrasound screening (TVS) test for ovarian cancer (OC) in asymptomatic women (N=540) undergoing an initial TVS screening test. Interviews were conducted prior to undergoing TVS screening and at 2 weeks and 4 months following this baseline. Women receiving an abnormal yet benign TVS test result (n=33) reported elevated OC-specific, but not general, distress at 2-week follow-up. Distress returned to baseline levels at 4-month follow-up. Consistent with the monitoring process and cognitive-social health information processing models, response to an abnormal TVS result was moderated by a monitoring coping style, low optimism, and a family history of OC. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impaired Higher Order Implicit Sequence Learning on the Verbal Version of the Serial Reaction Time Task in Patients With Parkinson's Disease.

Although neuroimaging studies have strongly implicated basal ganglia involvement in implicit sequence learning, serial reaction time (SRT) studies with Parkinson's disease (PD) patients have yielded mixed results. The present research sought to examine the ability of people with PD to implicitly learn sequences with different sequential structures and to objectively assess explicit knowledge. A version of the SRT task that reduces motor demands was used to compare 19 patients with PD but not dementia and 37 matched controls. PD patients showed less implicit sequence-specific learning for both sequences and reduced response time improvement over sequential trials for the more complex sequence. A closer examination revealed that the deficit involved higher order sequential associations as well as the learning of pairwise information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)