Modeling of industrial high pressure autoclave polyethylene reactor including decomposition phenomena

The aim of the present work is the development of a practical model for an industrial high-pressure polyethylene plant. The reactor considered in this work is the adiabatic slim type autoclave with four zones for free radical polymerization of ethylene. A fairly comprehensive but realistic model is described that has the ability to predict the temperature at each reaction zone as well as the effects of initiator flow changes. From the stability analysis we could identify the range of operating conditions which can effectively be used to prevent decomposition phenomena (runaway reactions) and to maximize polymer conversion in LDPE autoclaves.     

Spontaneous and induced labour are associated with different myometrial proteomes in the human

Human myometrium undergoes a major phenotypic change at labour likely involving modifications to key regulatory proteins. In some cases, the myometrium fails to activate normally and medical intervention is required to induce labour. In this study, 2‐D DIGE was used to examine changes in the myometrial proteome at the time of spontaneous (SL) and induced labour (IL). Proteomic profiles of nonlabouring term myometria (NL, n = 6) were quantitatively compared to SL (n = 6) and prostaglandin/oxytocin‐IL term myometria (n = 6). In SL samples, 23 differentially expressed protein spots were detected (9 increased/14 decreased compared to NL, p<0.05). In IL samples, 59 differentially expressed spots were observed (13 increased/46 decreased compared to NL). Comparison of SL and IL proteomes revealed 69 differentially expressed proteins (7 increased/62 decreased). Two proteins consistently decreased in SL and IL samples were identified as transgelin (1.98‐ and 1.97‐fold decrease in SL and IL, respectively) and αB‐crystallin (3.27‐ and 2.49‐fold decrease). Levels of desmin and cytosolic phospholipase A2 β were decreased 2.9‐ and 2.65‐fold, respectively only in IL samples. Our results show human labour is accompanied by general downregulation of specific myometrial proteins. Differences exist between SL and IL myometrial proteomes indicating divergence of underlying processes and highlighting the importance of distinguishing these groups in future studies of parturition. Our findings underscore the utility of discovery approaches in investigations of organ‐wide protein changes that underlie discrete physiological events including human labour.     

Application of partitioning and tearing techniques to sulfolane extraction plant

For effective flowsheet-level calculation of a complex chemical plant, the use of suitable partitioning and tearing techniques is inevitable. The partitioning and tearing techniques based on the reachability matrix and the decomposition algorithm were applied to model and simulate a sulfolane extraction plant. Basic concepts were first exploited towards a general representation for the modeling and simulation of the sulfolane extraction process. Six process units, which consist of the sulfolane extraction plant, were modeled first and partitioning and tearing techniques were employed to model and simulate the whole extraction plant. The Inside-Out method and the sequential-modular approach were used in the modeling and simulation. Results of simulations showed good agreement with plant operation data.     

Effects of nitridation pressure on the characteristics of gatedielectrics annealed in N2O ambient

Effects of N₂O pressure during oxynitridation on the characteristics of ultrathin gate dielectrics have been investigated. Reoxidation in N₂O ambient showed three distinguished oxidation regions as a function of tube pressure; that is, enhancement at 10-40 torr, retardation at 40-100 torr, and enhancement at 100-600 torr. The N₂O-nitridation at 40 torr incorporated much less nitrogen in oxide bulk than that at near-atmospheric pressure. The 40 torr N₂O-nitridation case exhibited about 70% of nitrogen incorporation at the Si/SiO₂ interface compared to that of the 600 torr N₂O-nitridation case. The low-pressure N₂ O-nitridation at 40 torr results in improvement of TDDB of gate dielectrics and the transconductance of nMOSFETs compared to the nitridation at near-atmospheric pressure. These data suggest that low pressure oxynitridation should be more recommendable for device application     

Correlation between activity and oxygen storage capacity of ceria on Pd-only three-way catalysts

One way of enhancing the thermal stability and NO_x, THC and CO conversion of a catalyst is to improve the thermal stability and oxygen storage capacity (OSC) of the ceria. The appropriate mixing ratios of bulk and stabilized ceria are especially very important for designing Pd-only three-way catalysts. In this paper, we discuss the surface phenomena of stabilized and unstabilized (bulk) ceria, the OSC of catalysts, and the correlation between activity and OSC of Pd-only catalysts with mixing ratios of bulk ceria and stabilized ceria.     

地面辐射供暖系统控制方式研究

在本研究中首先了解了韩国国内、外学者对地面辐射供暖系统提出的各种控制方式的原理,并根据影响控制方式的因素,对控制方式进行分类;然后分析讨论了控制方式所具有的特性,并以此为基础评价了各控制方式的适用范围。     

Labor market behavior in Washington: A cointegration approach

This study found a long run equilibrium relationship among population, labor force participation rate and employment, in which population is positively related to employment and negatively related to labor force participation rate. We proved that employment growth from new business investment causes increase in population in the state of Washington in spite of its beautiful environment and amenities. The causality does not operate in reverse way. We decomposed the time series into stationary components and non-stationary components and interpreted each component on the basis of historical economic condition of Washington. The response of the labor force participation rate to an impulse in employment supports Bartik's (1993) and Yeo and Holland's (2004) findings. Obviously the result is the opposite of Blanchard and Katz's (1992) finding that the long-run effect of job growth on the labor force participation rate is negligible. With regard to the party who benefits from job growth, we suspect that most of new jobs are captured by in-migrants because the pattern of the stationary component of employment and net migration is quite similar and the impulse response of population is significantly higher than that of employment.     

Effects of thermal processes after silicidation on the performanceof TiSi2/polysilicon gate device

The effects of thermal processes after silicidation on the gate depletion, threshold voltage (V_th) shift, drive current, and sheet resistance of TiSi₂/polysilicon (Ti-polycide) gate devices are evaluated. The dopant depletion of the polysilicon film, which is known to increase the V_th and to degrade the drive-current, increases with increasing temperature of the post-thermal process. However, the V_th roll-off characteristic in nMOSFETs is enhanced with increasing temperature. Furthermore, the drive-current is significantly degraded by the gate reoxidation process. The sheet resistance of the Ti-polycide gate increases with gate reoxidation as well as with increased post-thermal processes     

The role of polysilicon film in the suppression of bird's beak inpoly-buffered LOCOS

The oxidation behavior of buffer polysilicon and its contribution to the suppression of bird's beak in the polybuffered local oxidation of silicon (PBL) isolation have been studied. Shorter bird's beak in PBL than that in conventional LOCOS can be mainly attributed to the role of the buffer polysilicon, the oxidation of polysilicon is pinned near the LOGOS edge due to large compressive stress during field oxidation. The polysilicon-oxidation triangles caused by the oxidation pinning consume a large amount of laterally diffusing oxidants, thus leading to shorter bird's beak. The geometrical analysis of polysilicon-oxidation triangles enables us to reasonably explain the observed 2ΔW trends with PBL parameters