Retraction of published article due to the author’s proposal

. The article is devoted to creating a reliable algorithm for testing the quality of the education system, determining the system’s relationship with the goals of sustainable development, and the resolution of indicators of the socio-economic impact of the system. The substantiation of the application of analogies between testing software products and testing the dynamic system “quality of education” is presented. A type of relationship between the goal of sustainable development SDG 4 “Quality education” and other goals of sustainable development, particularly with SDG 8, “Decent work and economic growth” through the criteria for evaluating educational programs, is proposed. Based on the bibliometric analysis, the indicators of the socio-economic impact of the “quality of education” system are highlighted. The general algorithm for testing the design and the structural and logical diagram of the relationship between internal and external testing of the system are presented.


Introduction
The instantaneous spread of the infectious disease COVID-19 worldwide has fundamentally changed almost all spheres of human life.The education system belongs to the most social spheres of life, so it is not surprising that it had to be changed first.To prevent the severe consequences of the COVID-19 spread, educational institutions are forced to implement various electronic education mechanisms [32].The mechanisms include synchronous network platforms for collective interaction [12,29] as well as asynchronous distance learning technologies [18].In addition to the globally spread disease of COVID-19 [11,19], other important reasons for the introduction of electronic education technologies also remain relevant for many regions of the planet.In particular, for Ukraine, such a reason is open aggression on the part of despotic totalitarian empires [14].
The birth and development of distance education began even before the spread of the infectious disease COVID-19.As a result of the evolution and interconnection of such systems, a range of universal learning management systems (LMS) [17], integrated learning management systems (IMS) [1], and environment-specific management systems [2].Such systems are implemented to develop, manage and distribute educational materials.
Indeed, for teaching lectures, modern LMS systems allow easy use of network and video technologies [8].Instead conducting laboratory work with complex physical, engineering, or chemical equipment involves performing specific operations directly with this equipment, and performing each of these operations in a remote mode needs an individual solution [20,30].There are different ways of organizing laboratory work in such difficult conditions.The most common of these are virtual labs [5,22], remote labs [4,21] and intelligent expert systems [28].
Virtual laboratories, computer modeling, and simulation play an important role in such diverse scientific fields as physics, meteorology, neurology, nanoscience, sociology, economics, and archaeology [23].The importance of models is not limited to scientific research, simulators of various complex experimental installations of vehicles, mechanisms, and special equipment have also become widespread [13].In particular, the training of aircraft pilots begins with simulation devices.Students can gain the experience necessary for their further education as a result of performing a cycle of virtual experiments and laboratory work [5].In the case of the implementation of laboratory work in the form of virtual experiments [26], simulation cannot completely substitute a real experiment, since the simulation is valid only within the defined range of phenomena, the studied process belongs to [15].If you do not go beyond this range of phenomena, then the virtual experiment will fully satisfy the requirements and criteria of the experiment [24].
Among the variety of innovative approaches in education, the gamification of learning is widely used, which contributes to increasing the interest and involvement of students in learning.Works [9,27,31] consider several laboratory works and classes that contribute to a deeper motivation of students to study and involve students in research work.
Many scientific works consider the task of remote control of an experiment [10], which allow students to perform practical and laboratory work similar to those carried out in physical laboratories [3,7].
The set of considered approaches eloquently testifies to the importance of organizing a remote mode of conducting laboratory work and performing individual experimental research.Such a remote mode cannot now be considered as an optional additional accessory that only increases the convenience of the educational and research process.On the contrary, in many cases, it is the only possible mechanism for carrying out laboratory work or an experiment.Therefore, the development and improvement of technics for remote control of laboratory equipment remains quite relevant and fully corresponding to world trends now [16].
In recent decades, remote laboratories have been widely implemented in engineering education processes and integrated into e-learning frameworks offered to engineer and natural science students.Remote laboratory activities are used to support the life cycle of scheduled synchronous learning, as well as the organization of autonomous student learning.The document [6] provides an overview of modern technologies in the development of remote laboratory work and a description of the most vivid and relevant examples of the implementation of these technologies.
In this article, the authors offer a practical and reliable implementation example of the synchronous remote labwork.This study [25] is based on the wide application of popular and common general-purpose microcontrollers in education process.They clearly demonstrate and emphasize the need to consider remote laboratories as methodical pedagogical material, which is a significant and inseparable part of any synchronous remote labwork.A new and original approach to controlling an arbitrary laboratory device is presented, which includes a limited number of buttons for manual input of information and an indicator for visual output of information.The main goal of the work is to ensure effective operational interaction of the teacher with students and complete control over the quality and completeness of the laboratory assignment.

Design of the synchronous remote labwork
The learning management system can be easely replicated since it consists of only popular and globally common components.In particular, in the educational laboratory where the authors teaching, 7 copies of such a learning management system have already been created.System has been successfully and stably operated for 1.5 years.Each LMS instance runs independently of other instances of the same LMS.
As an example presented in the article, the object of research for students is the programming of Atmel ATMega8 microcontrollers, and the object of study is a development board with this controller.The layout board (figure 1) contains a matrix with an ATMega8 controller in the form of a DIP microcircuit; digital screen with four seven-segment digital indicators; a loudspeaker that allows you to output a sound signal; four buttons that can be pressed simultaneously or in any sequence.The board is connected by a 10-pin cable to a USBasp programmer.The USBasp programmer, in turn, is connected to the USB port of a workstation or laptop.
Previously, before the introduction of quarantine restrictions and the declaration of martial law, students worked with such mock-up boards directly: they programmed the controller through the USBasp programmer, connecting it to personal laptops, pressing buttons, and checking the result of the program by reading information on the screen.
Unfortunately, due to the reasons listed above, students cannot connect breadboards to their laptops and work directly with development boards now.Therefore, to fully replace such traditional work with mock-up boards, a laboratory learning management system (LMS) was created, consisting of the following hardware components: 1.A development board with an Atmel ATMega8 microcontroller and a USBasp programmer; 2. A webcam with a USB interface, which is defined in the system as a source of live broadcast (Imaging Device) and transmit a picture for the computer with a small pixel image from 480×320 to 720×480.3. Microcontroller ChipKit Uno32, to which a 4-pole low-level relay is connected (figure 2).This means that the the relay connected to a logical zero when the control signal is applied.Since the four buttons of the breadboard have one common contact, the breadboard is connected to the executive contacts of the 4-pole relay by means of a 5-pin loop.As a result, the ChipKit microcontroller plays the role of the student's "remote hand", with which he can independently press the buttons of the breadboard in any combination and in any sequence.Previously, before the introduction of quarantine restrictions and the declaration of martial law, students worked with such mock-up boards directly: they programmed the controller through the USBasp programmer, connecting it to personal laptops, pressing buttons, and checking the result of the program by reading information on the screen.
Unfortunately, due to the reasons listed above, students cannot connect development boards to their laptops and work directly with development boards now.Therefore, to fully replace such traditional work with development boards, a laboratory learning management system (LMS) was created, consisting of the following hardware components:

Student work procedure with the synchronous remote labworks
To start work, the student receives the IP address and TCP port necessary to establish a remote RDP session, the login and password combination from the teacher.The login must be unique within one operating system installed on the workstation.For example, the student receives the following access parameters from the teacher: For example, the authors teach laboratory work in the discipline "Microprocessor engineering" and use seven computers with the MS Windows Server operating system for this purpose.AVR Studio 5.0 integrated programming environment installed on each operating system, in which students create a new project for the target ATMega8 microcontroller and write a program in the C programming language.Experience shows that an average student writes a program in about 30-60 minutes, but it is possible to test the operation of the compiled program only on the microcontroller.So, a student spends 3-6 minutes on programming the ATMega8 microcontroller and checking the operation of the program on the microcontroller.
As you can see, in the ideal case, when the program does not need to be corrected and reworked, the student spends 90% of the time on developing the program, not using devices connected to the computer's USB bus at all.Obviously, many students can do this part of the work on one computer at the same time.Accordingly, the student spends 10% of the time checking the program and using USB devices -a camera, a programmer, and a ChipKit microcontroller for pressing buttons, and during the use of these three devices by one student, each of them must be blocked from accidental or intentional use by another student.Therefore, when more than one student works on the same computer, several students can finish creating and compiling the program the same time and proceed to programming the ATMega8 microcontroller.So the question arises "who is first?" and a queue may form.
So, the authors faced two tasks.First of all, use the working time of computers and in particular the operating time of the specified USB devices as rationally as possible.Secondly, to prevent the formation of a long queue of students who have to wait for the release of USB devices to check the operation of their program.In order to perform these two tasks simultaneusly, it is advisable to allocate one computer for two students, the first of which enters and works in the Windows Server operating system under the login Student1, the second -under the login Student2.Thus, 14  Each user's desktop has a shortcut to launch only the AVR Studio IDE, so each of the two students can launch independently of the other.Instead, there are no shortcuts for using USB devices on the desktop.programmer program is used to program the eXtreme Burner program is used to push the buttons of the breadboard with the ChipKit microcontroller PuTTYis used to view the webcam VLC Media Player.A student cannot launch all three programs using a shortcut.Instead, the authors developed a special program loader of these three programs under the conventional name Loader (figure 3).The software has 4 buttons.The first three of them launch eXtreme Burner, PuTTY, and VLC Media Player.But it is impossible to predict the result of pressing each of these buttons.This result depends on whether another student has run the same program.If this program has already been launched by another student.When you click on the button, a message will appear that the program has been launched by another student.Otherwise, pressing the button successfully launches the program.The fourth button sends an interactive message to all users of the system, which immediately appears on the desktop of each user, including the author of the message on top of all programs (figure 3).The message is distributed by the system command: msg * Please free up the USB devices!Another student working in a pair with the author of the message immediately sees this interactive dialog box and can do different things: send another message in response, close all programs to test the operation of the program on the ATMega8 microcontroller, perform both of these actions, or, conversely, ignore the message.Therefore, students have a reliable instant channel of communication between themselves, which allows them to use their time as efficiently as possible and achieve positive result.The full text of the Loader program in C# is show on figure 4. It is easy to see that when the program starts, only one statement InitializeComponents();, and all the rest of the program code consists of 4 functions that handle the events of pressing each of the 4 buttons.
For a brief summary, only the B1_Click() and B4_Click() event handlers are given in the article, because the B2_Click() and B3_Click() event handlers are identical to the B1_Click() event handler, but in the function cm1.Parameters.Add("ProcessName", "AVRProg"); instead of "AVRProg" have the values "vlc" and "putty", as well as in the function Process.Start("C:\\Users\\Burner.lnk"); have the corresponding full path to the program launch.

Program structure of the Chipkit Uno32 microcontroller
Microcontroller interacts with the operating system via the USB bus.Due to FT232RL microchip of FTDI on this microcontroller, the operating system emulates a serial port of the standard UART interface with a bitrate of 9600 bit/s.In the MS Windows operating system, such a serial port is called COM13, and in the GNU Linux operating system -TTY13.Instead of the number 13, there can be another number in the range 3-17.
Any terminal program can be used to interact with devices via standard UART/RS232/RS485 interfaces: HyperTerminal, MiniCOM, PuTTY.In synchronous remote laboratory work, the popular PuTTY is used, the name of which expresses for itself (Put→TTY).
PuTTY must be configured as a serial telnet client to a ChipKit microcontroller configured as a telnet server.In this way, the student can type any commands on the keyboard as a sequence of characters, and when the Enter button is pressed, these commands should be executed.Just like on a real telnet server accessible over a TCP/IP network.To do this, it is necessary to change a parameter of the PuTTY program, which is incompatible with working in telnet mode.When the user of the PuTTY program creates a new connection session using the SERIAL protocol, by default the characters entered from the keyboard are sent only to the interface channel and are not duplicated on the screen of the PuTTY program itself.As a result, the PuTTY user cannot see what command he entered and whether he made a mistake when entering it.For the entered keys to be sent to the interface channel and displayed on the screen at the same time, it is necessary to change the value of the Terminal|Local echo from the AUTO position to the FORCE ON (figure 5).As a result, echo works -the entered command is simultaneously displayed on the screen and sent to the device.
When the user successfully establishes a connection, a short instruction on the screen appears: "Enter FOUR digits: 1 -button NOT pressed, 2 -button is pressed during 0.5s, 3 -button is pressed permanently" (figure 6).It follows that the user can enter a command consisting of 4 digits from 1 to 3, for example 3121, 1211, 2113.Any other command that does not correspond to this format will be ignored.For that, the buttons of the breadboard with the ATMega8 microcontroller are numbered 1-4, and 1 is the leftmost button, 4 is the rightmost button (figure 6).Therefore, in order to press and release the button number 1, and not to press the other buttons, user needs to execute the command 2111, that is, the number 2 must be in the first position in the command.Similarly, commands 1211, 1121, and 1112 press and release the second, third, and fourth buttons.The 2222 command sequentially presses and after 0.5s releases all four buttons in sequence, but at any given time only one or none of the buttons is pressed.Instead, to control a program running on an ATMega8 microcontroller, it may be necessary for buttons with specific numbers to be pressed exactly at the same time for a short time.It is easy to do, but for this user needs to execute not one, but two commands in sequence.Example 1: in order to simultaneously press button 1 and 4, two commands must be executed: 3112, 1111.Example 2: in order to simultaneously press all buttons 1,2,3,4, two commands must be executed: 3332, 1111.Command 1111 is required to release all buttons on the breadboard and prepare it to press another key or key combination.Any correct command is executed exactly for 4 seconds.
To interpret such commands consisting of 4 digits, a special program is composed on the ChipKit controller (figure 7).The program consists of two parts, the first of which is executed once when the controller is turned on or restarted.The second part is the body of an infinite loop that is executed when any button on the keyboard is pressed.In the first part, all variables involved in the program are declared and their initial values are assigned.Pins P, P1, P2, P3, P4 are configured to output information: pin P is connected to the microcontroller's built-in LED, which lights up for 4 seconds when a command is executed, P1-P4 assigned to the control contacts of relay, each pole of which pushes the corresponding button of the breadboard, all contacts are assigned the value of logical zero with the help of statements D1(); D2(); D3(); D4();.These four statements complete the first part of the program.
The second part of the program begins with the construction "void loop() {".If the entered character turned out to be a number from 1 to 3. Then it is appended to the current line of the string type: rx_str += rx_byte;.If the entered character is not a number from 1 to 3, it is checked whether this character is the ENTER key.If true, the command execution procedure is started.If not true, the message "Not number" is displayed to the user (figure 6) and he can enter a new command without an error.
The procedure for executing a correctly entered command is as follows.The LED with contact P lights up, signaling the execution of the command: digitalWrite(P,HIGH);.The accumulated string of 4 digits from 1 to 3 is converted into a number of type Int: T=rx_str.toInt();.The following operators calculate the entered numbers b1, b2, b3, b4.Next, the analysis of the first number b1 is performed using the switch(b1) operator, and depending on its value at pin P1, the value of logical zero or one is set.Similarly, other numbers b2-b4 are sequentially analyzed and values are set to contacts P2-P4.At the end of the cycle, the prompt "Enter a number again:" is displayed to the user, the LED with the contact turns off, which visually means the end of the command execution: digitalWrite(P,LOW), the line with the accumulated digits of the current command is cleared: rx_str = "";, this completes the execution of the command.The user gets the opportunity to enter and execute the next command, this cycle is repeated.
As a result, the student's working environment consists of five applications: the integrated AVR Studio environment, the eXtreme Burner programmer program, the Loader program, the PuTTY terminal program, and the VLC Media Player (figure 8).The student always uses the first two applications from this list, including when he performs laboratory work immediately in the laboratory.The last three applications allow the student to perform the same laboratory work remotely.By the means of these programs, the student canoperate with real laboratory hardware in the mode of synchronous remote laboratory work.In combination with network platforms for collective interaction, the student will also be able to consult with teachers and other students, demonstrate his screen and report on the completed laboratory work.

Conclusions
Online platforms for collective interaction let the qualitative conduction of lectures, seminars and practical sessions, but the same platforms only allow the lecturer to demonstrate the correct performance of laboratory work.However, the development of modern information technologies makes it possible to build a specialized network channel, which allows authorized users to provide reliable and stable access to the computers of the internal private network of the educational institution and all programs running on these computers.
An almost unlimited number of students can work remotely on the same computer.Each must log in with their login, unique within the computer.If one copy of a specific program is installed on one computer, but several students remotely log in to this computer, the program can be downloaded to the desktop of each student.
If students must use programs that use external devices connected to the operating system via USB/FireWire/RS232 interfaces, only one user should be able to run such a program.To organize the queue of students, an additional loader must be used that starts the corresponding program only after checking the same program process is not launched by another student.
Laboratory computers on which students work remotely can have an additional microcontroller or a microcomputer to which an executive device is connected, for example, a multipole contactor.Such a device can help the student remotely push buttons and change the position of the switches of the laboratory equipment.Images of the hardware itself can be observed by students using a webcam opened in streaming media players such as VLC Media Player.

Figure 1 :
Figure 1: Development board with the microcontroller Atmel ATMega8.

Figure 5 :
Figure 5: Setting up the local echo in PuTTY program.

Figure 7 :
Figure 7: C code of program for microcontroller ChipKit UNO32.

Figure 8 :
Figure 8: Screenshot of student computer when he is demonstrating developed lab project working on microcontroller ATMega8.
socket............91.202.129.107:42161Login................Student1 Password.............4535365270 and opens a remote RDP session from his home computer.It can be done, for example, by other students who log on to the same computer identified by an IP socket with logins Student2 and Student3 and the corresponding passwords.But then students need to understand very clearly which operations they can do simultaneously, in parallel, and which, on the contrary, strictly sequentially, one after the other.The number of students simultaneously working on the same operating system depends on what part of laboratory work students can do simultaneously and independently, and what part only in the mode of coordination of their actions.
students can simultaneously perform laboratory work on 7 computers: