NQS

About: NQS is a research topic. Over the lifetime, 337 publications have been published within this topic receiving 4226 citations.

Implementation of Delay-Time-Based Nonquasi-Static Bipolar Transistor Models in Circuit Simulators

Abstract: We found that for a correct simulation of nonquasi-static (NQS) effect in compact bipolar transistor models, a dynamic or small-signal transit time must be used instead of the classical dc transit time. It is shown that the dynamic transit time is slowed down compared with the dc transit time of the intrinsic device owing to the bias-dependence of the latter. Since the instance value of the dynamic transit time is needed at the operating point, a formerly proposed scaling technique is used. The model shows perfect agreement with a widely accepted theoretical approach as well as with numerical device simulation.

Spectrophotometric Determination of Imipenem in Bulk and Injection Formulations by 1,2 Naphtho Quinone 4-Sulphonic Acid (NQS) Reagent

Abstract: A simple and cost effective spectrophotometric method is described for the determination of Imipenem (IMP) in pure and pharmaceutical formulations. The method is based on the formation of dark yellow colored chromogen when the drug reacts with 1,2 naphtho quinone 4-sulphonic acid sodium salt (NQS) reagent in alkalline medium. The method involves the addition of excess NQS of known concentration in the presence of 2.0 mL NaOH and the unreacted NQS was determined by the measurement of the λ max 449 nm, which was found to be the most suitable of several tests. This method was applied for the determination of drug contents in pharmaceutical formulations and enabled the determination of the drug in microgram quantities (0.5 to 3.0 mL). No interference is observed from excipients and the validity of the method was tested against reference method. The colored species has an absorption maximum at 449 nm for IMP (Method A) and obeys beer’s law in the concentration range 0.02 – 0.12 mg/mL of IMP. The apparent molar absorptivity is 0.0190 and sandell’s sensitivity is 7x10 -4 . The slope is 0.2284 ± 0.0118 and intercept of the equation of the regression line is 0.04971 ± 0.02144 . The optimum experimental parameters for the reaction have been studied and the validity of the described procedure was assessed. Statistical analysis of the results has been carried out revealing high accuracy and good precision. The proposed method was successfully applied for the determination of IMP in pharmaceutical formulations.

Evaluation of lookup-table non-quasi-static nonlinear models at microwave and mm-wave frequencies

Abstract: A comparison between two different, yet analytical approaches for lookup-table large-signal model construction is presented in this study. Both approaches use the same linear (small-signal) model as the starting point to construct the large-signal model. The first nonlinear model employs the charge- and current-sources to represent the nonlinearity of the active part of the device where the extended charge- and current-sources are added to compensate for the non-quasi-static (NQS) effects at mm-wave frequencies. The second nonlinear model employs the small-signal model schematic and adapts it to be used directly for large-signal simulations. The study was performed on SOI multi-Fin MOSFET transistors. Both modeling approaches can reproduce the device behavior at microwave and mm-wave frequencies and under highly nonlinear conditions with good accuracy.

Kinetic samplers for neural quantum states

Abstract: Neural quantum states (NQS) are a novel class of variational many-body wave functions that are very flexible in approximating diverse quantum states. Optimization of an NQS ansatz requires sampling from the corresponding probability distribution defined by squared wave function amplitude. For this purpose we propose to use kinetic sampling protocols and demonstrate that in many important cases such methods lead to much smaller autocorrelation times than Metropolis-Hastings sampling algorithm while still allowing to easily implement lattice symmetries (unlike autoregressive models). We also use Uniform Manifold Approximation and Projection algorithm to construct two-dimensional isometric embedding of Markov chains and show that kinetic sampling helps attain a more homogeneous and ergodic coverage of the Hilbert space basis.