Fouling Enhancement under Flow Boiling at Elevated Steam Qualities

Under laboratory conditions of flow boiling in water at 272–285°C (5.7 to 7.0 MPa), it has been observed that fouling rates by colloidal iron oxides ( crud ) dramatically increase upon reaching a certain steam quality and mixture velocity. In loop tests, an increase in fouling rates by up to 3 orders of magnitude was repeatedly observed. This effect is called here “heavy fouling under elevated steam quality” (HFESQ). HFESQ is potentially very significant for once-through steam generators, and very large versions of recirculating nuclear steam generators, because it can lead to heavy fouling in the upper tube bundle. The mechanism of HFESQ is not certain, but its onset appears to be associated with significant droplet entrainment after the transition of flow to the annular pattern. The postulated connections between the flow pattern and the fouling mechanism will be discussed. This mechanism may also be the reason for an increased rate of flow-accelerated corrosion at high steam quality in piping and piping fittings. Experimental data will be shown suggesting that the onset of HFESQ is susceptible to the chemistry and size of the crud particles. This offers a route for possible mitigation of the fouling problem

Identification and Testing of Amines for Steam Generator Corrosion and Fouling Control

AECL and EPRI have been evaluating candidate amines for control of corrosion and fouling in recirculating nuclear steam generators. To permit an unambiguous ranking of the suitability of the candidate amines, the characteristics of base strength, volatility, price, steam generator fouling, cost of associated condensate and blowdown polishing, toxicity and ecotoxicity have been summarized in a single numerical index. The majority of the data required for the calculation of the index is available in the literature. The effect of amine on steam generator fouling has been measured using a recirculating loop at AECL under flow boiling conditions. The loop results coupled with steam generator modelling indicate a significant reduction in steam generator fouling rates when optimized chemistry is used. The calculated reduction in the cost of steam generator fouling and corrosion control for several amines and amine mixtures is given

Measures for Ph.D. Evaluation: the Recruitment Process

In the last years the quality of Higher Education (HE) system and its evaluation have been key issues of the political and scientific debate on education policies all over Europe. In the wide landscape that involves the entire HE system we draw attention on the third level of its organization, i.e. the Ph.D. In particular, this paper discusses the necessity of monitoring the recruitment process of Ph.D. system because it represents a fundamental aspect of the Ph.D. system as a whole. We introduce a set of concepts related to the recruitment process and then we make them computable with synthetic indicators. The study provides an empirical analysis based on doctoral schools of four academic years at the University of Siena. Proposed indicators are finally used for detecting weakness and strength of each Ph.D. school

Preoperative rectal cancer staging with phased-array MR

<p>Abstract</p> <p>Background</p> <p>We retrospectively reviewed magnetic resonance (MR) images of 96 patients with diagnosis of rectal cancer to evaluate tumour stage (T stage), involvement of mesorectal fascia (MRF), and nodal metastasis (N stage).</p> <p>Our gold standard was histopathology.</p> <p>Methods</p> <p>All studies were performed with 1.5-T MR system (Symphony; Siemens Medical System, Erlangen, Germany) by using a phased-array coil. Our population was subdivided into two groups: the first one, formed by patients at T1-T2-T3, N0, M0 stage, whose underwent MR before surgery; the second group included patients at Tx N1 M0 and T3-T4 Nx M0 stage, whose underwent preoperative MR before neoadjuvant chemoradiation therapy and again 4-6 wks after the end of the treatment for the re-staging of disease.</p> <p>Our gold standard was histopathology.</p> <p>Results</p> <p>MR showed 81% overall agreement with histological findings for T and N stage prediction; for T stage, this rate increased up to 95% for pts of group I (48/96), while for group II (48/96) it decreased to 75%.</p> <p>Preoperative MR prediction of histologically involved MRF resulted very accurate (sensitivity 100%; specificity 100%) also after chemoradiation (sensitivity 100%; specificity 67%).</p> <p>Conclusions</p> <p>Phased-array MRI was able to clearly estimate the entire mesorectal fat and surrounding pelvic structures resulting the ideal technique for local preoperative rectal cancer staging.</p

Social change and the family: Comparative perspectives from the west, China, and South Asia

This paper examines the influence of social and economic change on family structure and relationships: How do such economic and social transformations as industrialization, urbanization, demographic change, the expansion of education, and the long-term growth of income influence the family? We take a comparative and historical approach, reviewing the experiences of three major sociocultural regions: the West, China, and South Asia. Many of the changes that have occurred in family life have been remarkably similar in the three settings—the separation of the workplace from the home, increased training of children in nonfamilial institutions, the development of living arrangements outside the family household, increased access of children to financial and other productive resources, and increased participation by children in the selection of a mate. While the similarities of family change in diverse cultural settings are striking, specific aspects of change have varied across settings because of significant pre-existing differences in family structure, residential patterns of marriage, autonomy of children, and the role of marriage within kinship systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45661/1/11206_2005_Article_BF01124383.pd