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This paper presents the design of undervoltage relay settings for an industrial plant with cogeneration units to prevent critical loads from tripping due to voltage sags. The critical loads that are sensitive to voltage sags in the plant have been identified from actual system fault contingencies. The power quality of these loads is enhanced by quickly islanding the subsystem with cogeneration units before tie line tripping with an external Taipower system. According to the transient stability analysis of the rest of the industrial power system near a Taipower network, the critical loads that are nonsensitive to voltage sags are disconnected from external system faults in time to restore the system stability with the execution of proper load shedding. To ensure the normal operation of critical and voltage-sensitive loads by considering the voltage tolerance curves, the proper relay settings for tie line tripping of the internal subsystem has been determined. This way, the critical loads and cogeneration units in the industrial power systems can be survived from system faults to mitigate the production loss of industrial customers. Index Terms--Cogeneration system, power quality, transient stability analysis, voltage tolerance curve.

This paper investigates the effect of boiler steam system on transient response of turbine generators for an incinerator plant. By performing the test of cogeneration units, the mathematical models of turbine generator, governor, and boiler have been identified, which are used in the computer simulation to solve the steam pressure and system frequency of the cogeneration system for islanding operation after tie line tripping. Due to the variation of trash heat value, the power output of the cogeneration unit is stochastically varied with the steam generation for normal operation, which will cause the dynamic change of tie line power flows. For the severe fault contingency of external power systems, the cogeneration system will be isolated by tie line tripping, and the system frequency response is then determined by including the boiler effect to represent the dynamic steam generation. Because of more sluggish response of the boiler system caused by unstable trash heat value, the transient response of the incinerator governor system is inferior to that of conventional industrial cogeneration systems. To maintain the system stability for successful islanding operation of the incinerator plant, the amount of load shedding after tie line tripping has to be properly determined based on the transient stability analysis by considering the response of boiler system. Index Terms--Boiler model, cogeneration system, load shedding, transient stability.

Over the past decades, flocculation and/or sedimentation processes have been adopted to remove pollutants from CSOs. It has been learned that major factors affecting settlement of pollutants are the particle size distribution, their settling velocities and their specific gravity. It is, therefore, a good idea to analyze the particle size distribution and settleability of CSOs pollutants in order to develop details in designing a process. Discussed in this study are pollutant characteristics of CSOs such as particle size distribution and settleability of pollutants. The power law function is applied and is found to be an effective and reliable index for expressing the particle size distribution of pollutants in CSOs. Based on the particle size spectrum analysis, the tendency toward settling and simultaneous flocculation-settling phenomenon of CSOs pollutants is described. Based on the regression analysis it is observed that the derived constants of curves representing settling velocity profile are proportional to the initial concentration of particles and to the #-values of power law distributions. It is also revealed that the simultaneous flocculation-settling processes are effectively described by the changes of the average particle diameter and of the #-values of power law distributions. [ABSTRACT FROM AUTHOR]

In this study, fully vitellogenic oocytes of the longchin goby (Chasmichthys dolichognathus) were exposed toin vitroxenoestrogens such as diethylstilbestrol (DES), bisphenol A (BPA) and nonylphenol (NP) at concentrations of 100 ng/ml in the presence of [3H]17a-hydroxyprogesterone as precursor. The major metabolites producedin vitroare progestogens [17a-hydroxy,20a-dihydroprogesterone (17a20aOHP) and 17a-hydroxy,20ß-dihydroprogesterone (17a20ßOHP)], androgens [androstenedione (A4) and testosterone (T)] and estrogens [estrone (E1) and estradiol-17ß (E2)]. Comparative activities of these chemicals in oocyte steroid biosynthesis showed as follows: NP treatment resulted in clear stimulation of estrogen production, while the opposite occurred in DES treated incubation. Treatment with DES resulted in a higher synthesis of 17a20aOHP. BPA treatment increased the androgen, while estrogen synthesis was slightly inhibited. These results suggest that NP exhibited clearly estrogenic activity on the three chemicals. [ABSTRACT FROM AUTHOR]