Modeling of char particle size/conversion distributions in a fluidized bed gasifier: non-isothermal effects

Mass and thermal energy balances are developed to describe the time-dependent behavior of reacting char particles distributed in both size and conversion in continuous, steam—oxygen, fluidized-bed gasifier. These relations are solved numerically utilizing the method of orthogonal collocation to simulate both steady-state and time-dependent behavior. The influences of superficial gas velocity, mechanical removal of solids, and reactants gas concentration on steady-state bed characterisctics and particle size/conversion distributions are determined. An investigation is made of particle heating times, and the validity of neglecting temperature profiles in reacting char particles is confirmed. These heating times are compared to the dynamics governing solids flow and particle size/conversion distributions. The transient responses of solids holdup and the distributions are presented to show the dynamic effects of step changes in solids feed rate, superficial gas velocity, and particle-size distribution in the feed.     

Participants’ personal note-taking in meetings and its value for automatic meeting summarisation

This paper reports the results of novel quantitative research on multiple people’s personal note-taking in meetings with the long-term aim of aiding the creation of innovative meeting understanding applications. We present three experiments using a large number of group meetings taken from the Augmented Multi-party Interaction meeting corpus. Statistical techniques were employed for this work. Our findings suggest that temporal note-taking overlap information and the semantic content of the written private notes taken by many meeting participants both point to the majority of the most informative meeting events. Thus, the characteristics of note-taking can be seen as a contributing feature for new automatic meeting summarisation approaches and for the development of future meeting browser environments that better support the needs of individuals and organisations.     

ePTFE纤维技术的创新:性能、应用和机会

叙述了W.L.Gore Associates公司ePTFE纤维的新发展:高温下的高拉伸强度、改善的耐磨性、一致的纤维直径、特定用途的密度、符合要求的表面结构、可在广泛范围内调节的弹性模量,以及能与大量填料结合的能力。应用一项待审的专利技术可能是首次制成了新型稳定化的低收缩100%PTFE织物。     

Entrapment and displacement of nitrous oxide in a drained pasture soil

The objective of this work was to investigate a possible reason for the `unaccounted for ¹⁵N' fraction, of ¹⁵N mass balances, being so large in pasture systems, namely: the displacement and physical release of entrapped N₂O gas from within a soil profile. A soil core was placed inside a purpose built perspex glovebox and the internal N₂O concentration was continuously monitored. KNO₃ was applied followed by periodic applications of distilled water. After 256 h the soil core was physically broken open in an attempt to release any N₂O which may have been entrapped in the soil core. Instantaneous increases in glovebox N₂O concentrations occurred when surface applied water displaced N₂O from the base of the soil core and when the soil core was broken open (equal to 9.5% of N applied). The relative contribution these two mechanisms make will depend on the concentration of denitrification products present, the frequency and volume of irrigation/rainfall and the duration of the experiment.     

Human papillomavirus genotype as a major determinant of the course of cervical cancer

PURPOSE: To determine whether the prognosis of invasive cancers of the uterine cervix is related to the type of human papillomavirus (HPV) associated with the tumor. PATIENTS AND METHODS: Two hundred ninety-seven patients with invasive cervical cancer were prospectively registered from 1986 to 1994. HPV typing was performed on DNA extracted from frozen tumor specimens by means of Southern blot hybridization (SBH) and polymerase chain reaction (PCR) techniques. The median follow-up was 38 months. RESULTS: HPV sequences were detected in 246 patients (83%): 150 patients had HPV16, 31 patients had HPV18, and 14 patients had one of the intermediate-oncogenic-risk HPV types (HPV31, 33, 35, 52, 58). In 51 patients, HPV type remained undetermined, and in 51 patients, no viral sequences were found. No significant associations were observed between virologic data and tumor stage or node status. The 5-year disease-free survival (DFS) rate was 100% for patients with intermediate-risk HPV-associated tumors, 58% for patients with HPV16-positive tumors, and 38% for patients with HPV18-positive tumors (P = .02). In multivariate analysis, patients with HPV18-associated tumors had a relative risk (RR) of death 2.4 times greater (95% confidence interval [CI], 1.29-4.59) than that for patients with HPV16, and 4.4 times greater (95% CI, 3.48-5.32) than that for patients with a tumor associated with a viral type different from HPV16/18. CONCLUSION: The prognosis for invasive cancers of the uterine cervix is dependent on the oncogenic potential of the associated HPV type. HPV typing may provide a prognostic indicator for individual patients and is of potential use in defining specific therapies against HPV-harboring tumor cells.