SLAG MONITORING SYSTEM FOR COMBUSTION CHAMBERS OF STEAM BOILERS

The computer based boiler performance system, presented in this paper, has been developed to provide a direct and quantitative assessment of furnace and convective surface cleanliness. Temperature, pressure and flow measurements and gas analysis data are used to perform heat transfer analysis in the boiler furnace and evaporator. Power boiler efficiency is calculated using an indirect method. The on-line calculation of the exit flue gas temperature in a combustion chamber allows for an on-line heat flow rate determination, which is transferred to the boiler evaporator. Based on the energy balance for the boiler evaporator, the superheated steam mass flow rate is calculated taking into the account water flow rate in attemperators. Comparing the calculated and the measured superheated steam mass flow rate, the effectiveness of the combustion chamber waterwalls is determined in an on-line mode. Sootblower sequencing can be optimized based on actual cleaning requirements rather than on fixed time cycles contributing to lowering of the medium usage in soot blowers and increasing of the water-wall lifetime

EFFECT OF THERMAL CONTACT RESISTANCE ON THE HEAT TRANSFER IN PLATE FINNED TUBE HEAT EXCHANGERS

Plate fin-and-tube heat exchangers are made by inserting oval tubes through sheet metal strips with stamped holes and then expanding the tubes slightly to cause pressure at the tube-to-strip contacts. The gap between the fin base and the outer tube surface may be filled with air or corrosion products causing a decline in the ability of plate fins to transfer heat. The contact resistance must be accounted for in the design and performance calculations of heat exchangers. In this paper, the thermal contact resistance of the fin-to-tube attachment is estimated from the condition that the dimensionless correlations for the Colburn j-factors obtained from two different methods are in good agreement. The first method is based on the experimental data, while the second one on the CFD simulation of the flow and heat transfer in the heat exchanger

FEM-Based Thermal Analysis of Underground Power Cables Located in Backfills Made of Different Materials

Выполнен предварительный расчет температурного поля в подземных высоковольтных линиях электропередач, которые планируется использовать в электростанции мощностью 600 МВт. Исследуется система из трех силовых кабелей, размещенных в трубах из полиэтилена низкого давления, с многослойной засыпкой (грунт и термоизолирующие материалы). Рассматриваются различные конфигурации размещения слоев засыпки. Глубина размещения силовых кабелей, измеряемая от реперной точки (0,5 м ниже уровня грунта), варьируется от 2 до 6 м, что оказывает влияние на температурное распределение в грунте, изоляционном и проводящем слоях кабелей. С использованием метода конечных элементов выполнен численный расчет установившихся температурных полей. Для дополнительного учета влияния сформированной так называемой “сухой зоны” на распределение температуры постулируется зависимость теплопроводности грунта от температуры.Виконано попередній розрахунок температурного поля в підземних високовольтних лініях електропередач, які планується використовувати в електростанції потужністю 600 МВт. Досліджується система з трьох силових кабелів, що розміщені в трубах із поліетилену низького тиску, з багатошаровою засипкою (ґрунт і термоізольовані матеріали). Розглядаються різні конфігурації розміщення шарів засипки. Глибина розміщення силових кабелів, що вимірюється від реперної точки (0,5 м нижче рівня ґрунту), варіюється від 2 до 6 м, що впливає на температурний розподіл у ґрунті, ізоляційному і провідному кабелях. Із використанням методу скінченних елементів виконано числовий розрахунок усталених температурних полів. Для додаткового врахування впливу сформованої так званої “сухої зони” на розподіл температури постулюється залежність теплопровідності ґрунту від температури

Clinical and kidney structural characteristics of living kidney donors with nephrolithiasis and their long-term outcomes

Background: Nephrolithiasis in living kidney donors is concerning due to the potential impact on long-term postdonation kidney function. Methods: We performed a cohort study of living kidney donors from 2 centers with a baseline computed tomography scan and implantation renal biopsy. Donors (\u3e5 y since donation) completed a follow-up survey or underwent chart review to assess eGFR and incident hypertension. Stone formers were classified as symptomatic if they had a past symptomatic episode or asymptomatic if only incidental radiographic kidney stones were identified during donor evaluation. We compared baseline clinical, imaging, and biopsy characteristics by stone former status including review of metabolic evaluations in stone formers. Long-term risks of renal complications (low eGFR and hypertension) by stone former status were evaluated. Results: There were 12 symptomatic and 76 asymptomatic stone formers among 866 donors. Overall, baseline clinical characteristics and implantation biopsy findings were similar between stone formers and non-stone formers. After a median follow-up of 10 y, stone former status was not associated with eGFR \u3c60 mL/min/1.73 m2, eGFR \u3c45 mL/min/1.73 m Conclusions: Both asymptomatic and symptomatic SF have favorable histology findings at baseline. Long-term kidney outcomes were favorable in select stone formers with no evident increased long-term risk for decreased kidney function or hypertension after donation

Emotional Well‐Being of Living Kidney Donors: Findings From the RELIVE Study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109345/1/ajt12906.pd

Age-Related Impairment of Ultrasonic Vocalization in Tau.P301L Mice: Possible Implication for Progressive Language Disorders

Tauopathies, including Alzheimer's Disease, are the most frequent neurodegenerative diseases in elderly people and cause various cognitive, behavioural and motor defects, but also progressive language disorders. For communication and social interactions, mice produce ultrasonic vocalization (USV) via expiratory airflow through the larynx. We examined USV of Tau.P301L mice, a mouse model for tauopathy expressing human mutant tau protein and developing cognitive, motor and upper airway defects.At age 4-5 months, Tau.P301L mice had normal USV, normal expiratory airflow and no brainstem tauopathy. At age 8-10 months, Tau.P301L mice presented impaired USV, reduced expiratory airflow and severe tauopathy in the periaqueductal gray, Kolliker-Fuse and retroambiguus nuclei. Tauopathy in these nuclei that control upper airway function and vocalization correlates well with the USV impairment of old Tau.P301L mice.In a mouse model for tauopathy, we report for the first time an age-related impairment of USV that correlates with tauopathy in midbrain and brainstem areas controlling vocalization. The vocalization disorder of old Tau.P301L mice could be, at least in part, reminiscent of language disorders of elderly suffering tauopathy

Glycolate Oxidase Isozymes Are Coordinately Controlled by GLO1 and GLO4 in Rice

Glycolate oxidase (GLO) is a key enzyme in photorespiratory metabolism. Four putative GLO genes were identified in the rice genome, but how each gene member contributes to GLO activities, particularly to its isozyme profile, is not well understood. In this study, we analyzed how each gene plays a role in isozyme formation and enzymatic activities in both yeast cells and rice tissues. Five GLO isozymes were detected in rice leaves. GLO1 and GLO4 are predominately expressed in rice leaves, while GLO3 and GLO5 are mainly expressed in the root. Enzymatic assays showed that all yeast-expressed GLO members except GLO5 have enzymatic activities. Further analyses suggested that GLO1, GLO3 and GLO4 interacted with each other, but no interactions were observed for GLO5. GLO1/GLO4 co-expressed in yeast exhibited the same isozyme pattern as that from rice leaves. When either GLO1 or GLO4 was silenced, expressions of both genes were simultaneously suppressed and most of the GLO activities were lost, and consistent with this observation, little GLO isozyme protein was detected in the silenced plants. In contrast, no observable effect was detected when GLO3 was suppressed. Comparative analyses between the GLO isoforms expressed in yeast and the isozymes from rice leaves indicated that two of the five isozymes are homo-oligomers composed of either GLO1 or GLO4, and the other three are hetero-oligomers composed of both GLO1 and GLO4. Our current data suggest that GLO isozymes are coordinately controlled by GLO1 and GLO4 in rice, and the existence of GLO isozymes and GLO molecular and compositional complexities implicate potential novel roles for GLO in plants