Fast exact state-estimation algorithm based on quadratic equations using sparse matrix inversion

A method of effecting an iterative AC load flow as part of a generalized nonlinear state estimator is described. The estimation equations are a redundant set of quadratic algebraic equations when expressed in Cartesian form. Their Taylor expansion contains terms up to the second order. Consequently, the Jacobian and covariance matrices are constant during the iteration procedure. The use of the sparse inverse matrix method reduces the computational requirement.     

Energy-efficient noise-tolerant dynamic styles for scaled-down CMOSand MTCMOS technologies

A new high-speed domino circuit, called HS-Domino has been developed. HS-Domino resolves the tradeoff between performance and reliability in conventional CD-domino logic while dissipating low dynamic power with minimal area overhead. HS-Domino, therefore, extends domino's operation in the deep submicron regime. A multithreshold implementation of HS-Domino is also devised to achieve substantially low leakage values during standby, while maintaining high performance and low power during the active mode. Furthermore, the generic multithreshold scheme is applied to differential cascode voltage switch (DDCVS) logic     

Studies on the formation of alpha-amylase by Thermomonospora vulgaris

Conditions affecting the formation of alpha-amylase by static cultures of the thermophilic actinomycete Thermomonospora vulgaris were studied. The organism failed to grow under submerged culture conditions or when the culture medium was devoid of CaCO3-alpha-Amylase was produced during the logarithmic phase of growth and maximum yield was obtained after 3 to 9 days of incubation. Growth and amylase formation took place only in a range from 45 degrees to 55 degrees C; optimum temperature was 55 degrees C. Of the tested carbon sources only starch induced enzyme formation. Maximum enzyme yield was obtained when starch concentration of the medium was 2% and when ammonium citrate served as a nitrogen source. Crushed clay pots could substitute for CaCO3 of the medium, but growth and amylase yield were less.     

Power system topological error detection and identification

The problem of detecting and identifying power system network changes is considered. An algorithm based on nodal power balance is developed using the output of a state estimator in which bad data has been filtered. Since lost data can be suspected for network disconnections, and vice versa, the two problems of detecting and identifying these errors are inseparable. The developed algorithm, however, does succeed in identifying both types in most cases. Examples on a 5-bus and 29-bus system are given.     

Creation of reactive centers on cotton. II

Acrylamidomethylated cellulose (AMC) was prepared by reacting cellulose with N-methylolacrylamide or its ethers in acidic medium under a variety of conditions. The extent of the reaction, expressed as mmole double bonds per 1 g cellulose, increased by increasing the concentration of N-methylolacrylamide or its ethers. However, the paddry-cure technique produced AMC with greater amounts of double bonds than the pad-batch technique. Also, the reactivity of the etherifying agents follow the order N-methylolacrylamide>N-methoxymethylacrylamide>N-methoxymethylmethacrylamide. Furthermore, the behavior of AMC in neutral, alkaline, and acidic media was studied. No change in the amount of the pendent double bonds of AMC occurred in neutral medium regardless of the conditions employed. On the contrary, disappearance of the double bonds took place in alkaline medium. The extent of disappearance depends on the kind of alkali used as well as on the conditions implemented. It was disclosed that consumption of the pendent double bonds of AMC occurred mainly via addition of the cellulose hydroxyls to yield a crosslinked cellulose. Treatment with hydrochloric acid, on the other hand, resulted in partial splitting of the acrylamidomethyl groups as well as addition of the acid on the pendent double bonds of AMC.     

Optimization of acyclovir oral tablets based on gastroretention technology: factorial design analysis and physicochemical characterization studies

The purpose of this research was to prepare a floating drug delivery system of acyclovir. Floating matrix tablets of acyclovir were developed to prolong gastric residence time and increase its bioavailability. The tablets were prepared by direct compression technique, using polymers such as hydroxypropylmethylcellulose 4000, Compritol 888. Sodium bicarbonate was used as a gas-generating agent. A 32 factorial design using the Design Expert Software (version 7.1.6) was applied to optimize the drug release profile systematically. The amounts of hydroxypropylmethylcellulose 4000 (X?) and Compritol 888 (X?) were selected as independent variables and the percentage drug released in 1 (Q?), 6 (Q?), and 12 (Q??) h as dependent variables. The results of factorial design indicated that a high level of both hydroxypropylmethylcellulose 4000 (X?) and Compritol 888 (X?) favors the preparation of floating controlled-release of acyclovir tablets. Also, a good correlation was observed between predicted and actual values of the dependent variables chosen for the study. By fitting the data into zero-order, first-order, and Higuchi models, we concluded that the release followed Higuchi diffusion kinetics. Storage of the prepared formulations at 40°C/75% relative humidity for 3 months showed no significant change in drug release profiles and buoyancy of the floating tablets. We can conclude that a combination of hydroxypropylmethylcellulose 4000, Compritol 888, and sodium bicarbonate can be used to increase the gastric residence time of the dosage form up to 12?h. These floating tablets seem to be a promising gastroretentive drug delivery system.     

A physically-based flood volume distribution model

An analytically derived distribution model for flood volume is presented. The model is based on water balance computations during a rainstorm at the soil surface. It is applicable for mountainous watersheds with alluvial channels. Three hydrologic processes are considered: precipitation, infiltration, and runoff generation. Rainfall intensity and duration are presented with exponential distributions. They are assumed to be statistically independent. A linear rainfall-runoff relationship is proposed for the mountainous areas. The mountain runoff is regarded as a uniformly distributed water depth on the alluvial channels. The rainfall excess in the alluvial channels is computed to be equal to this depth plus the rainfall depth minus the infiltration losses. Infiltration in the channels is presented with Philip's expression, coupled with an empirical model for the computation of a long-term average value for the soil moisture content. The distribution model is verified through applications for three gauged watersheds in Saudi Arabia: Wadi Liyyah (174 km²), Wadi Turrabah (3720 km²), and Wadi Khulays (5220 km²). The results are found to be in a good agreement with observations.On leave from the Irrigation and Hydraulics Department, Faculty of Engineering, Cairo University, Giza, Egypt.     

Microwave characterization and modeling of the surface impedance offractal structure copper films

The surface impedances of two thin metallic films of different fractal structures realized on printed circuits have been measured in free-space over the frequency range [10 GHz-20 GHz]. A modeling scheme based on Maxwell's equations and Fresnel's diffraction theory is proposed     

Field evaluation of the NOVA Celltrak 12 hematology analyzer

An evaluation of the NOVA Celltrak 12 was performed over a 6-week period. Precision, linearity, carryover, and reproducibility of values compared favorably to manufacturers' claims. The correlation was performed using the Coulter S Plus VI as the reference instrument and yielded coefficients of correlation for measured parameters of greater than .98 with the exception of RDW at r = .84, MCV at r = 0.96, and MPV at r = .92. Three-part differential information and an expanded flagging system affords increased clinical information and trouble-shooting guides. The three-part differential information compared favorably with that of the Coulter S Plus VI with lymphocyte percentage r = .96, granulocyte percentage r = .94, and monocyte percentage r = .50. We conclude that this instrument performed well in a clinical setting.