SAFSIM theory manual: A computer program for the engineering simulation of flow systems

The paper describes a computer program for analysis and simulation of large-scale water distribution networks. The simulation facility enables the evaluation of system hydraulic and cost operation over extended time periods. An efficient user interface has been provided which allows interactive operation with graphical displays. The program computations use well established network solution techniques together with a range of specially developed models. With these features, the program has now been accepted as a powerful tool with a number of practical applications throughout the water industry.

This work deals with the investigation of the effect of a more recent, powerful control algorithm, called Pseudo Derivative Feedback, PDF, on the performance of a hydraulic servomechanism. The controlled system behavior is theoretically evaluated by developing a mathematical model for the controlled system and by using a computer simulation program. Also, the experimental measurement of the system dynamic performance is conducted. The developed simulation program is validated by comparing theoretical and experimental results of the system response. The simulation program is used to deduce a transfer function for the studied servomechanism. Once the transfer function of the controlled system is obtained, the control algorithm implementation is performed. To define the advantages of the proposed control algorithm, its output is compared to that of the already existing unity feedback system. Finally, A proposal for the design of the PDF controller is presented.

A computer simulation program for evaluation of the continuous heat treatment of particulate food products. Part 1: Design

Development of a numerical method for the performance analysis of thermoelectric generators with thermal and electric contact resistance

NS5B is the RNA-dependent RNA polymerase responsible for replicating hepatitis C virus (HCV) genomic RNA. Despite more than a decade of work, the formation of a highly active NS5B polymerase·RNA complex suitable for mechanistic and structural studies has remained elusive. Here, we report that through a novel way of optimizing initiation conditions, we were able to generate a productive NS5B·primer·template elongation complex stalled after formation of a 9-nucleotide primer. In contrast to previous reports of very low proportions of active NS5B, we observed that under optimized conditions up to 65% of NS5B could be converted into active elongation complexes. The elongation complex was extremely stable, allowing purification away from excess nucleotide and abortive initiation products so that the purified complex was suitable for pre-steady-state kinetic analyses of polymerase activity. Single turnover kinetic studies showed that CTP is incorporated with apparent K(d) and k(pol) values of 39 ± 3 μM and 16 ± 1 s(-1), respectively, giving a specificity constant of k(pol)/K(d) of 0.41 μM(-1) s(-1). The kinetics of multiple nucleotide incorporation during processive elongation also were determined. This work establishes a novel way to generate a highly active elongation complex of the medically important NS5B polymerase for structural and functional studies.

Developability assessment of clinical drug products with maximum absorbable doses

The authors sought to verify computer simulation of visual fields by comparing thresholds of real and corresponding simulated visual fields. Four patients with stable glaucomatous visual fields and three patients with progressing glaucomatous visual fields were chosen for the study. Visual fields had been recorded at 6-month intervals for 5 to 7.5 years. A previously described computer simulation program was used to generate a corresponding simulated visual field for each of the real fields. Twenty different levels of response variability and long-term variability were used in the simulations. Pointwise sensitivity differences between real and simulated fields were calculated. The average difference and 95% interval of the differences were analyzed for the different simulation conditions, for the pointwise sensitivities in the real patient fields, and to determine whether the field was stable or progressing. In almost all simulation conditions, the average pointwise sensitivity differences ranged from -1 to 1 dB and were not significantly different among different simulation conditions. The 95% interval of the average difference increased significantly with response variability, whereas long-term variability failed to show any apparent effect. Average pointwise differences and the 95% intervals were greatest in locations where the real-patient field had reduced sensitivity of 14 dB or worse. The simulation program provided good estimates of visual field sensitivities. Increasing amounts of response, but not long-term variability, produced a linear increase in the variability of threshold sensitivities. This finding implies that short-term rather than long-term fluctuation is the most important factor determining the variability of thresholds.

A randomized control trial comparing use of a novel electrocardiogram simulator with traditional teaching in the acquisition of electrocardiogram interpretation skill

This paper describes the problems, mainly from a standpoint of circuit stability, in the case in which we analyze and design analogue integrated circuits using a computer simulation program. Although a fundamental condition of an analogue circuit is whether DC bias can be determined stably or not, computer simulation is not good at this stability check and it is pointed out that an unstable circuit is sometimes checked to be stable accidentally. In the circuit partitioning process used in large‐scale integrated circuits, a risk that is shown in examples is that, depending on the manner of partition, its subcircuit may become unstable and it makes analysis of the whole circuit impossible. As an example we take SPICE, a representative program for analogue circuit simulation, to discuss the problem of default values in the program, direct current bias analysis, one that inside of a computer is assumed to be ideal, and the necessity of transient analysis. Then it clarifies the importance of correct modeling of circuit elements and careful usage of a simulation program after good understanding of its properties.

The equilibrium constant for iodine hydrolysis at elevated temperatures has been investigated using absorption spectroscopy and a simulation computer program. The temperature dependence of the aqueous I2 maximum extinction coefficient for visible light (at 460 nm) was first evaluated in a preliminary experiment using saturated I2 solution. The time dependence of I2 concentrations in dilute solution has subsequently been measured using the temperature-dependent extinction coefficient. The results were analysed by the simulation program, in which 11 normally accepted reactions were considered, and the equilibrium constant, K, was estimated. It was concluded that the K value at temperatures ranging between 25 and 120 °C may be expressed by log K(T)= 13880/T– 0.2445T+ 308.4 log T– 749.1, where the units of K and T are mol2 dm–6 and K, respectively.

Program for computer simulation on photoproduction of mesons decaying into two photons

Onchocerciasis control strategies

Analytical theory of low and medium energy ion reflection by target surface atoms during sputtering

In this study, two support tools are developed for construction of a dynamic simulation program for engineering systems (especially nuclear systems) by combining software modules. These are (1) a sub-system to support the module selection suitable for dynamic simulation and (2) a graphical user interface to support visual construction of simulation programs. The support tools are designed to be independent on the conception of software modules (data communication methods between modules). In the module selection sub-system of item 1, a module is characterized beforehand by keywords for several criteria. The similarity between the characteristic of requested module by users and that of registered modules in the module library is estimated by a weighted average of similarity indexes for criteria. In the module selection sub-system, the weights are flexibly extracted from users by applying the analytic hierarchy process. The graphical user interface helps users to specify both calling order of modules and data transfer between two modules. The availability of the support tools is evaluated by several sample problems of module selection and dynamic simulation model construction. The support tools will be a strong tool for the efficient usage of software modules.

The Workshop in Fluid Mechanics and Population Dynamics: Models, Existence Problems, Stability and Numerical Methods took place in Hadath (Lebanon), at the Laboratory of mathematics in the Doctoral School of Science and Technology of the Lebanese University, during the week September 10 - September 14, 2012 The workshop was held with the support of the Ecole Centrale de Nantes, the Laboratoire de mathématiques Jean Leray of Nantes university and the universities of Paris 13 and Poitiers, and was organized by Samer Israwi, Basam Kojok, Ayman Mourad, Mazen Saad, Zaynab Salloum and Raafat Talhouk. It was attended by about 60 PhD students and Mathematicians coming from universities from different countries, such as Algeria, France, Lebanon and Tunisia. The workshop included courses tutorials and sessions around specific themes in which participants presented their works. It was open to any scientist interested in academic or industrial applications. It was aimed at doctoral students in mathematics, as well as senior researchers. Its objective was firstly to present a synthesis of various partial differential equations involved in fluid mechanics and populations dynamics, and on the other hand to present more recent advances in research topics such as asymptotic models in fluid mechanics, homogenization and the finite volume method. All the contributions to this special volume were submitted to regular peer review, according to the rules of the journal Discrete and Continuous Dynamical Systems - Series S. We deeply thank all the authors for their high quality papers and the Editors of the journal for their interest in the topics of the workshop. We express our heartfelt thanks to the following sponsors: Ecole Central de Nantes and Laboratoire de Mathématques Jean Leray, Nantes University, represented by Mazen Saad, Université de Poitiers, represented by Alain Miranville, Université Paris 13, represented by Mikhael Balabane, Lebanese National Council for Scientific Research (CNRS) and Lebanese University. Finally, we express our sincere thanks to the Dean of the Doctoral School of Science and Technology at the Lebanese University, Professor Zeinab Saad, for her support throughout the workshop and to the French Embassy in Beirut, represented by its Scientific Counselor, Mr. Gilles Théodet.