IEEE Circuits and Systems Magazine - Q3 2021 - 67

1) The student to learn how to apply the NVM to any
AC/DC circuit (linear and passive).
2) The student to compare the output of the
U=RIsolve application to his/her own methodology,
as well as the Branch currents/Node voltages
computed in QUCS with the analytical ones.
3) The educator to produce practical examples, both
off-class (e.g. to prepare exercises, lab scripts or
lectures) and in-class (in real-time, demonstrating
the application of the NVM through case-studies).
The remainder of this paper is organised as follows:
Section II describes the main stages of the U=RIsolve
application from the users perspective. The interface,
along with the step-based output is outlined in Section
III. The paper is concluded with brief discussions on
how this tool will evolve in the future, clarifying its employment
for in-class instruction.
II. Application Work Flow
The U=RIsolve application uses the QUCS [14] netlist file
as an input to the analysis algorithm. A netlist describes
the components' attributes and interconnections being
automatically generated after simulation in most
of Spice-based circuit simulators. This implies users to
perform an a priori simulation in order to generate the
netlist file needed for the U=RIsolve analysis.
As Fig. 1 shows, Step 1 involves the circuit drawing-
here users must create the schematics using QUCS,
name the Nodes using the available wire label and correctly
place the reference Node (necessary for the NVM
analysis). From the moment these requirements are met,
users simply need to simulate the circuit and extract the
netlist (using the Simulation taskbar panel or by pressing
the F6 key). That leads to the file upload stage (2) at the
U=RIsolve application website, where users are allowed
to submit a netlist and an optional image file containing
the circuit schematic that will further be appended to
the output and provide solution better intuition. Lastly,
it is just necessary to click on the analysis method to
execute the algorithm and obtain the results. Although
work in progress addresses extending the U=RIsolve application
to other circuit analysis methods, options beyond
the NVM are still disabled.
The final stage (3) corresponds to the step-based solution
presented by U=RIsolve. This solution was formerly
designed to: enhance the students comprehension of
the NVM algorithm by granting a progressive analysis
progress; reduce miscalculations by segmenting the
equation system and results into different steps; and to
keep the students interested in the resolution methods
offering interactive attributes, graphical representations,
as well as maintaining a simplified language and
content structure. Additionally, the solution output proTHIRD
QUARTER 2021
vides methods for downloading the analysis in various
formats: PDF, JSON and TEX.
III. User Interface
The U=RIsolve application features a web-based user interface
responsive to any screen size/resolution, which
Figure 1. U=RIsolve simulation process-drawing, uploading
and output.
IEEE CIRCUITS AND SYSTEMS MAGAZINE
67
IEEE Circuits and Systems Magazine - Q3 2021

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