Residual flux impact in controlled switching of HVDC converter transformer

Converter transformers are an interface point of HVDC frameworks and are basic hardware from activity and reliability view point. Converter transformers are turned off intentionally under planned support and un-deliberately during fault conditions. Random energization of HVDC Converter transformer delivers high inrush currents due to core saturation asymmetries and endanger equipment health. In this paper, charging approach has been proposed. By utilizing point on wave exchanging for moderation of charging drifters during charging of 888 MVA 400/325 kV Converter Transformer of ±800 kV HVDC Sub-station. The proposed procedure has been applied on HVAC electrical Circuit Breaker furnished with Pre-Insertion Resistor considering diverse degree of residual flux. Performance of proposed philosophy has been affirmed by field tests and reproduction in PSCAD programming package and is found very viable. Near investigation is done in this paper and shows that with the use of proposed system, the switching transient during stimulation and field tests of coupled three phase converter transformers is decreased to worthy level.

Welfare-maximizing transmission capacity expansion under uncertainty

We apply the JuDGE optimization package to a multistage stochastic leader–follower model that determines a transmission capacity expansion plan to maximize expected social welfare of consumers and producers who act as Cournot oligopolists in each time period. The problem is formulated as a large-scale mixed integer programme and applied to a 5-bus instance over scenario trees of varying size. The computational effort required by JuDGE is compared with solving the deterministic equivalent mixed integer programme using a state-of-the-art integer programming package. This article is part of the theme issue ‘The mathematics of energy systems’.

Flight Stability Analysis of a Flexible Rocket Using Finite Elements and Reduced-Order Modeling

The coupling of advanced structural and aerodynamic methods is a complex and computationally demanding task. In many cases, simplifications must be made. For the flight simulation of flexible aerospace vehicles, it is common to reduce the overall structure down to a series of linked degenerate structures such as Euler-Bernoulli beams in order to expedite the structural portion of the solution process. The current study employs the sophistication and generality of finite-element based modeling with the concepts of reduced-order modeling to create a general flexible-body flight simulation program. The program was created for use with the MATLAB-Simulink programming package. A parametric analysis on the stability of flexible rockets is performed and results are presented for a variety of rocket configurations based on the SPHADS-1 vehicle under development at Ryerson University. The primary instability mode under study is that associated with the flapping and twisting motions of the tailfins under aerodynamic loading. By varying the average fin thickness, both stable and unstable behaviour is recorded for a variety of flight conditions.

Flight Stability Analysis of a Flexible Rocket Using Finite Elements and Reduced-Order Modeling

The coupling of advanced structural and aerodynamic methods is a complex and computationally demanding task. In many cases, simplifications must be made. For the flight simulation of flexible aerospace vehicles, it is common to reduce the overall structure down to a series of linked degenerate structures such as Euler-Bernoulli beams in order to expedite the structural portion of the solution process. The current study employs the sophistication and generality of finite-element based modeling with the concepts of reduced-order modeling to create a general flexible-body flight simulation program. The program was created for use with the MATLAB-Simulink programming package. A parametric analysis on the stability of flexible rockets is performed and results are presented for a variety of rocket configurations based on the SPHADS-1 vehicle under development at Ryerson University. The primary instability mode under study is that associated with the flapping and twisting motions of the tailfins under aerodynamic loading. By varying the average fin thickness, both stable and unstable behaviour is recorded for a variety of flight conditions.

On Analysis of Seismic Vibrations Data Applying Doppler Effect Expression

In the paper, a possibility to develop the digital models of the seismic vibrations parameters is analyzed. To reach this goal, the observations at seismic station LUWI (Indonesia) were processed applying the statistical procedures. In fact, the biggest attention was given to the introduction of the Doppler effect expression and the employment of the theory of covariance functions. The trend in vectors of vibrations intensities values was detected and estimated upon using the least-squares method and polynomial approximation. In addition, by this technique, the random errors were eliminated partially. The self-developed computer programs based on Matlab programming package procedures were applied.

Optimal Regulation of Variable Speed Pumps in Sewer Systems

In this work, the optimal regulation of variable speed pump (VSP) was solved by means of two optimization algorithms: a mixed-integer optimizer based on the BONMIN (Basic Open-Source Nonlinear Mixed Integer Programming) package, and an original hybrid genetic algorithm (GA) called GA–Powell’s direction set method (PDSM), which employs a derivative free inner optimizer, that is, the Powell’s direction set method (PDSM). The obtained results show how the use of a strategy based on the optimal regulation of VSP allows to obtain huge energy cost savings. The analysis of the results shows that the regulation of the plant does not apparently follow a general rule.

Software documentation with markdoc 5.0

markdoc is a general-purpose literate programming package for generating dynamic documents, dynamic presentation slides, Stata help files, and package vignettes in various formats. In this article, I introduce markdoc version 5.0, which performs independently of any third-party software, using the mini engine. The mini engine is a lightweight alternative to Pandoc (MacFarlane [2006, https://pandoc.org/ ]), completely written in Stata. I also propose a procedure for remodeling package documentation and data documentation in Stata and present a tutorial for generating help files, package vignettes, and GitHub Wiki documentation using markdoc.

Flexible Job Shop Scheduling using Software

This present paper speaks about Flexible Job Shop scheduling Problem using a software. Flexible Job shop scheduling is most typical and complex manufacturing environments in production planning issues. A case study was conducted on a manufacturing business set in Vijayawada. Information collected from the producing company to get the time taken by the conventional scheduling method and gathered data for 5 jobs requiring 8 machines that arrived during the analysis period. The Project additionally speaks about the study of varied programming strategies, learning of LEKIN programming package is a software tool has a flexibility to develop new heuristic models to produce effective schedules be applied practically. Input data, taken from the manufacturing company, converted to tables and routing sequences. The LEKIN programming package [3], develops the different schedules for given data with reference to priority rules, such as First Come First Serve (FCFS), Longest Processing Time (LPT), Shortest Processing Time (SPT), Earliest Due Date (EDD), Critical Ratio (CR) [6]. The schedules obtained from priority rules analysed through performance measures like Make Span, No of late jobs, Total Flow Time, Total Tardiness, Maximum Tardiness, Total Weighted Tardiness, Total Weighted Flow Time. Our goal is to come up with a optimized schedule with in the process of flexible job shop scheduling by using LEKIN scheduling software, using various priority rules as mentioned above and to minimize the make span i.e. the time length of the schedule, during which all the operations for all jobs is completed in an engineering company

THE EXPERIMENTAL-THEORETICAL METHOD FOR FINDING ELASTIC MODULES OF RUBBER-LIKE MATERIALS BASED ON THE VERASONICS ACOUSTIC SYSTEM

The experimental-theoretical method for determining the elastic characteristics of rubber-like materials is presented. This method is founded on the technology SWEI (Shear Wave Elasticity Imaging) with using the open architecture Verasonics speaker system that implements a method for generating and measuring shear wave velocity in rubbery media. The SWEI method makes it possible to measure the shear wave velocity (and, accordingly, elastic characteristics: Young's and shear modules) in soft biological tissues and finds application in medical diagnostics – shear wave elastography. The results of measuring the elastic characteristics of rubber-like media are presented. For physical modeling, polymer CIRS phantoms (Model 049 Elasticity QA Phantom Spherical) were used as measurement media. Young's modules of different types of polymer calibrated phantom measured on the Verasonics acoustic system are comparable with the tabular values. Numerical modeling of the evolution of shear waves in rubber-like media is carried out. Numerical analysis was performed using the k-Wave programming package. This programming package is based on k-space transition, where spatial gradients are computed using a Fast Fourier Transform scheme and temporal gradients are computed using a corrected k-space difference scheme. The k-Wave programming package combines the optimization of the MATLAB programming environment for working with matrix operations and a set of tools that allows you to simulate an ideal (non-dissipation) propagation environment using parameters such as density and sound velocity for a given rubber-like material. The combination of these factors allows you to model 2D and 3D spaces while maintaining high computational speed. For polymer CIRS phantoms, the results of physical and numerical modeling are compared to determine the elastic characteristics of rubber-like media.