Evaluation of production costs of two interconnected electric power systems by the segmentation method

This paper develops the methodology, based on the segmentation method, to evaluate the production costs of two interconnected systems. The demand plane is divided into a grid structure, or segments, of equal size. Each segment contains the joint probability of the occurrence of load in the range of the selected segment as well as the first moments, or expected values, of load, or equivalent load, and residual tie line capacity for each system. The methodology proposed is accurate and computationally efficient. The method is applied to the evaluation of expected energy generation, unserved energy as well as production costs of two interconnected systems. The impact of tie line capacity variations, forced outage rate changes as well as joint ownership of generation is investigated.     

46 XX male: a case of sex reversal syndrome

Methamphetamine is an amphetamine derivative and a category II controlled substance. It is uncommonly prescribed by physicians, but is more often used illegally as a stimulant. In this case study, 3 dogs were believed maliciously poisoned. Methamphetamine was detected in the stomach contents of 1 dog. One died and 2 recovered after gastrointestinal decontamination and supportive care. The recommended treatment protocol of methamphetamine toxicosis should also include urine acidification and alpha-adrenergic blocking agents.     

Efficacy of oral ganciclovir in prevention of cytomegalovirus infection in post-kidney transplant patients

We devised a diagnosis and management algorithm for acute onset of central diabetes insipidus (CDI), and conducted a retrospective evaluation of its efficacy. Fourteen patients admitted to our pediatric intensive care unit (PICU) over a three year period were diagnosed with acute CDI secondary to various brain injuries. All patients were treated as per the algorithm guidelines. The initial dose of aqueous vasopressin ranged from 0.25 to 1.0 mU/kg/h. Low sodium content solution (0-0.5 normal saline) was used to replace urine output in excess of 3 ml/kg/h and for maintenance fluid therapy. The therapeutic goals included: urine output 2-3 ml/kg/h, urine specific gravity 1.010-1.020 and serum sodium 140-145 mEq/l. The pitressin dose was adjusted as deemed necessary to achieve the aforementioned goals. Our results indicate that urine specific gravity is the most sensitive parameter to respond to treatment. It was the best determinant of the adequacy of pitressin dose as it had the best linear correlation with it (r = 0.96; p = 0.009). Urine output was second best (r = 0.93; p = 0.02), whereas no linear correlation was established between pitressin dose and serum sodium concentration, nor with serum osmolality. We conclude that the algorithm developed and used by us for the management of CDI is generally efficacious. Changes in urine specific gravity follow changes in pitressin dose very closely and thus should be used as the primary parameter for determination of intravenous pitressin dose adjustment.     

Model Predictive Control of Wind-Excited Building: Benchmark Study

In this paper, a “third generation” benchmark problem that focuses on the control of wind excited response of a tall building, using the Model Predictive Control (MPC) scheme, is presented. A 76 story, 306 m tall concrete office tower proposed for the city of Melbourne, Australia, is being used to demonstrate the effectiveness of MPC. The MPC scheme is based on an explicit use of a prediction model of the system response to obtain the control actions by minimizing an objective function. Optimization objectives in MPC include minimization of the difference between the predicted and desired response trajectories, and the control effort subjected to prescribed constraints. By incorporating input/output hard constraints, the MPC scheme provides an optimal control force that satisfies the prescribed constraints.     

Surge response statistics of tension leg platforms under wind and wave loads: a statistical quadratization approach

Commonly, in offshore applications, frequency domain analyses of nonlinear systems have been approximately carried out using the method of equivalent statistical linearization. This method, however, fails to capture the non-Gaussianity of the response in terms of its higher-order statistics. In addition, response energy in frequency ranges outside that of the input spectrum is not observed using this technique. Herein, a method of equivalent statistical quadratization is proposed, whereby a statistically asymmetric nonlinearity in the forcing of a tension leg platform (TLP) is cast in a quadratic form. The present quadratization method takes advantage of the Gaussianity of the first order response to simplify the recasting of the nonlinearity in its approximate polynomial form. A Volterra series approach leads to the development of transfer functions from which the response spectrum as well as statistics of the response may be obtained. Response cumulants, computed up to fourth order via direct integration or the Kac-Siegert technique, reveal the non-Gaussian character of the response which was hidden by linearization and, when used in the framework of some available non-Gaussian probability density function models, indicate acceptable agreement with time-domain simulations of the original nonlinear differential equations. In addition, the response power spectral density contains an additional peak near the resonant frequency of the TLP, where input energy at difference frequencies of the input spectrum lies, corroborating information gleaned from the time-domain simulation.     

Association of malignant brain tumors and cancers of other sites

PURPOSE: We conducted an exploratory study of brain tumors that occurred as a second primary malignancy to identify potential risk factors for brain tumors. METHODS: Using data from the Surveillance, Epidemiology, and End Results (SEER) Program, we calculated the sex-specific standardized incidence ratio (SIR), adjusted to age and time period, as an estimate of the relative risk (RR) of developing a second primary brain tumor following other cancers. RESULTS: We found an elevated RR of brain tumors after bladder cancer in both men (RR, 1.7; 95% confidence interval [CI], 1.2 to 2.3) and women (RR, 1.7; 95% CI, 0.8 to 3.2); this effect was present for both astrocytoma and glioblastoma multiforme. Elevated RRs of brain tumors were also found after sarcoma (RR, 4.4; 95% CI, 1.8 to 9.0) and leukemia (RR, 2.9; 95% CI, 1.6 to 4.8) in men, and after colorectal cancer (RR, 1.8; 95% CI, 1.3 to 2.4) and endometrial cancer (RR, 1.4; 95% CI, 1.0 to 1.9) in women. The highest RR observed in this study was for CNS lymphoma following any first primary malignancy in men (RR, 7.9; 95% CI, 5.5 to 11.0). CONCLUSION: The associations of brain tumors with bladder, colorectal, and endometrial cancers in women, and an increased occurrence of CNS lymphoma as a second malignancy in men, are new findings that have not been described previously.     

Wind and solar generating units: Potential candidates for a generation mix of an isolated area

A power industry always looks for an optimal generation mix. This paper investigates the potentiality of a wind turbine generator (WTG) and a photovoltaic generator (PVG) as competing candidates in a generation mix of an isolated area. The investigation considers two basic aspects of generation expansion analysis: reliability and cost. The WTG, at its present status related to cost and also at its possible future status, is compared with the conventional thermal unit. Similar investigation is made in the paper for the PVG. Unlike many attempts in the past, the temperature dependent probabilistic models of WTGs and PVGs are developed for the evaluation of reliability and cost. The paper also shows an application of temperature dependent probabilistic models of WTGs and PVGs in generation expansion analysis.     

Sensitivity Study of the Cumulant Method for Evaluating Reliability Measures of Two Interconnected Systems

The rationale for using the cumulant method to take advantage of its computational efficiency is well known among power system planners. However, although an analysis of the sensitivity of the univariate Gram-Charlier series has been investigated, an equivalent analysis of the sensitivity of the bivariate Gram-Charlier series has not yet been reported in the literature. This paper investigates the sensitivity of the bivariate Gram-Charlier series in the evaluation of reliability for several types of interconnected systems. The impact of different number of terms in the series on the accuracy of the results as well as on the computational requirements is also investigated. Load correlation between the interconnected systems is considered. As anticipated, the cumulant method is much faster than the commonly used recursive method. However, the reliability indexes, obtained using this method for interconnected systems with low reserve margin and with units of low forced outage rates can not be trusted. The relative error in the calculation of the loss of load probabilities increases with the increase of tie line capacity. However, the error is greatly reduced if the systems have units of higher forced outage rate. The use of additional terms in the bivariate Gram-Charlier series increases somewhat the accuracy of the results but also increases the computational time.     

Effect of parametric uncertainties on wind excited structural response

This paper addresses the influence of parametric uncertainties on the wind excited response of structures. Based on the available experimental data from both laboratory and field studies, the variability in the parameters related to the wind environment and meterological data, kinematics of wind flow field, wind-structure interaction and structural properties is assessed. The random variability in the parameter space is propagated to ascertain its influence on the structural response statistics utilizing a Monte Carlo simulation technique. By means of an example, the influence of parametric uncertainties on the dynamic response of a tall reinforced concrete chimney is presented. The analysis of simulated data suggests a need for further improvement in the modeling of wind-structure interaction, prediction of natural frequencies and damping, and a reduction in the variability of extreme wind estimates.     

Radio frequency response of flexible microstrip patch antennas under compressive and bending loads using multiphysics modeling approach

This research article studies the effect of compression and bending loads on resonant frequency of microstrip patch antennas using COMSOL Multiphysics software (will be called COMSOL hereafter). In this study, copper microstrip patch antenna of dimension 30 mm × 25 mm on polydimethylsiloxane (PDMS) substrate of dimension 50 mm × 50 mm is considered. The interface bonding is assumed to be ideal between the patch and substrate. Both Ansoft HFSS and COMSOL are used to model and analyze the original geometry of the microstrip patch antenna without applying physical load to make sure that the design and the impedance match is satisfactory. Then, COMSOL is used to find deformed shape of the microstrip patch antenna under different values of compression and bending loads. The deformed geometries are reanalyzed using COMSOL radio frequency (RF) simulation. The resonant frequencies at different load levels are obtained and the effect of loading and boundary conditions on the resonant frequency shift is discussed.