Master Unit Research Articles

Implementation of Wastewater Monitoring System using Low-Cost Water Sensor and IoT-based SCADA

Wastewater monitoring is crucial for ensuring the wastewater quality is in the allowable range. This paper presents the implementation of a wastewater monitoring system using low-cost water sensors and Internet of Things (IoT)-based Supervisory Control and Data Acquisition (SCADA). The low-cost water sensor comprises the pH, temperature, turbidity, and Dissolved Oxygen (DO) sensors. The sensors are connected to the ESP32 microcontroller that is equipped with the WiFi module for communicating with the master unit, namely the Haiwell CBOX. Since the Haiwell CBOX is an IoT-based device, it is connected to the IoT cloud server. Thus, it can be accessed remotely through the Internet. The experimental results show that the user-friendly graphical interface is easy to develop and provides the user with useful and helpful information for monitoring and analyzing wastewater parameters. Further, the communication time interval of four seconds between the ESP32 and CBOX achieves a stable connection.

基于PTO协议的变量喷雾系统设计与试验

The aim of this research is to address the issues of low precision in variable spraying within the existing farmland application system, whereby nozzles cannot be controlled independently and low pesticide utilisation is observed. A variable spraying system based on PTO protocol has been designed. The system comprises an STM32 microcontroller as the control core, including the host computer, multi-channel controller, electronic switch, and electromagnetic spray nozzle. The master control unit receives the spray amount set by the user and calculates the duty cycle of the corresponding nozzle, which is then sent to the multiplex controller in real time through CAN communication. The multiplex controller adjusts the on-off frequency and duty cycle of each electromagnetic nozzle in real time according to the duty cycle of the corresponding nozzle it receives, thus enabling the nozzles to be controlled independently. This study offers theoretical and technical support for the independent control of spray nozzles and the optimisation of pesticide utilisation for variable spray systems based on PTO protocols.

The Performance Comparison of Multiloop PID Controller on NCS Temperature Plant Based on UDP and TCP

Hardware implementations of networked control systems (NCS) are still rarely found in various research publications so that technical issues, such as how to measure random delay and substitute it into the control equation, still need to be studied further. This study is therefore aimed to compare the performance of NCS based on the used protocol in the ethernet network, i.e. user datagram protocol (UDP) or transmission control protocol (TCP), by applying it in room temperature plant. In this study, the controlled plant is influenced by the fan speed, heating, and window position plant. The heating plant is employed as the main control, while the others are set as sub-plants. The three plants use proportional–integral–derivative (PID) controller where they are regulated by fuzzy logic as the master control unit (MCU). The MCU and three PID controllers are located in the master terminal unit (MTU) while the actuators and sensors are located in the three different remote terminal units (RTU). The verification experiment shows that there is no overshoot on TCP-based NCS, while UDP has 0.725%. For the risetime, the response on UDP is faster than TCP (110.22 as compared to 138.18 s). The same thing also happened to the settling time, where the time with UDP was 101.86 s and 128.44 s for TCP.

SECOND ORDER SLIDING MODE CONTROL FOR ISLANDED AC MICROGRIDS WITH RENEWABLE POWER RESOURCES

Microgrids have attracted a lot of attention and are the future power systems. This paper proposes a new control scheme for islanded AC microgrid (MG) using master-slave technique. Stability and high performance are vital for islanded MG. Two second order sliding mode controls (SMCs) are designed in stationary reference frame for master and slave units to control the voltage and powers respectively. Both designed controls guarantee the convergence of considered outputs to their reference values. The proposed controls are robust, simple, chattering free and only need local measurements. The control method proposed in this paper can be easily extended to microgrids with any number of slave units and parallel connected inverters. The effectiveness of the proposed control scheme is verified through simulation results in SIMULINK/MATLAB environment and compared to feedback linearization control and a modified conventional SMC.

Teachers’ Perception Towards Inclusive Education

This study aimed to assess the perception of teachers handling inclusive education at the identified public elementary schools in Loon South District, Bohol Province, for the school year 2022–2023 as the basis for instructional skills enhancement plans. The respondents comprised three clusters of grades one to six teachers handling inclusive classes. The respondents were selected using universal sampling and treated using inferential and descriptive statistics. Results showed that most respondents aged 44-53 were female, married, with master units, specialized in general education, and taught for 8-14 years. Moreover, the level of perception of the respondents towards inclusive education was very positive. It was also found that there was no significant difference between respondents’ profile and their perceptions of inclusive education. Therefore, results showed that respondents were very optimistic about handling inclusive classes. It is recommended that the instructional enhancement plans be implemented for a more positive learning experience when dealing with inclusive classes.

Adaptive walking control for quadruped robot by using oscillation patterns.

To improve the adaptability of quadruped robot in multiple scenarios, an adaptive locomotive system based on the double-layered central pattern generator (CPG) is proposed. The novel CPG network consists of double master units and subsets of slave units based on gyroscope signals including yaw and pitch angle. The response of master units provides the ability to control the 1st joins of quadruped robot, while slave units can generate the symmetry signals to control the 2nd and 3rd joints. The CPG network enables the seamless switching of locomotion gaits to stops and starts by using an ultrasonic sensor. Through adjusting the mutually dependent parameters, joints can generate the joint angles to achieve steering behavior. For adaptive movement on an irregular surface, stable ranges of the robot body yaw and pitch angles are proposed by using gyroscope signals. The experimental results verify that the quadruped robot with the proposed double-layered CPG network can perform stable trot pattern in a complex environment.

The Use of Open Educational Resources (OERs) among Mathematics Teachers in Public Secondary Schools

This study investigated the utilization of Open Educational Resources (OERs) among mathematics teachers in selected public secondary schools in Zambales, Philippines for the school year 2022-2023. A survey was conducted with 75 Junior High School Mathematics teachers to assess OERs usage frequency and extent, identify challenges, examine perceptions of OER's effect on mathematics teaching practices, and propose a development plan for promoting OER utilization. Findings revealed that the typical teacher-respondent was a 33-year-old female with a bachelor's degree, supplemented by master's units, and eight years of teaching experience. They held the position of Teacher III and were familiar with OERs. Respondents sometimes used OERs in their math teaching strategies and disagreed with challenges related to OERs use. They agreed that integrating OERs into mathematics teaching had positive effects. The study observed no significant differences in challenges faced by mathematics teachers when grouped by age, sex, highest educational attainment, years of teaching experience, and teaching position. However, significant differences emerged when grouped by OER knowledge. Likewise, there were no significant differences in perceptions of OER effects when respondents were grouped by profile variables. Furthermore, no significant relationships were found between challenges and OER utilization or between perceptions of OER effects and OER utilization among respondents.

Outage Analysis of Unmanned-Aerial-Vehicle-Assisted Simultaneous Wireless Information and Power Transfer System for Industrial Emergency Applications.

In the scenario of a natural or human-induced disaster, traditional communication infrastructure is often disrupted or even completely unavailable, making the employment of emergency wireless networks highly important. In this paper, we consider an industrial Supervisory Control and Data Acquisition (SCADA) system assisted by an unmanned aerial vehicle (UAV) that restores connectivity from the master terminal unit (MTU) to the remote terminal unit (RTU). The UAV also provides power supply to the ground RTU, which transmits the signal to the end-user terminal (UT) using the harvested RF energy. The MTU-UAV and UAV-RTU channels are modeled through Nakagami-m fading, while the channel between the RTU and the UT is subject to Fisher-Snedecor composite fading. According to the channels' characterization, the expression for evaluating the overall probability of outage events is derived. The impact of the UAV's relative position to other terminals and the amount of harvested energy on the outage performance is investigated. In addition, the results obtained based on an independent simulation method are also provided to confirm the validity of the derived analytical results. The provided analysis shows that the position of the UAV that leads to the optimal outage system performance is highly dependent on the MTU's output power.

Sensor Based Flood & Landslide Pre-Alert System

The proposed system is an advanced early warning system designed to mitigate disasters such as landslides and floods by providing crucial minutes of warning. It consists of a wireless sensor network deployed on the slopes of landslide and flood-prone mountainsides. The network utilizes a Node MCU topology, and for demonstration purposes, a two-node system is suggested. The nodes in this system are equipped with various sensors to gather essential data. They utilize a tipping rain sensor to measure precipitation and an accelerator to detect potential landslides by monitoring module position changes. Additionally, there's a humidity sensor continuously monitoring surface temperature changes. These sensor nodes transmit their data to a central base station, which acts as a receiver. Both the public and the base station are equipped with Node MCU microcontrollers to facilitate communication. The base unit, positioned at a strategic location, such as the district collector's office, utilizes a long-range transmitter to communicate with the master unit. When the sensor nodes detect significant landslide or flood activity within a specific time frame, indicating a potential flash flood, this critical information is transmitted to the master unit. The master unit responds by activating an alarm and promptly sending messages to relevant officials and the general public through Node MCU microcontrollers connected to it. This swift communication allows for timely evacuation and response measures to minimize the impact of the disasters.

A Supervisory Control System for Automation of Horizontal Form-Fill-Seal Packaging Plant Based on Modified Atmosphere Technology

Abstract The packaging industry is one of the most important parts of agricultural products processing. A popular method of increasing the shelf life of agricultural products is modified atmosphere packaging (MAP). The main objective of this paper was to increase the adaptability and flexibility of the machines for packaging of different vegetables including lettuces, broccolis, cabbages, cauliflowers, etc. To achieve this goal, a supervisory control and data acquisition (SCADA)-based system was designed and developed for controlling and monitoring of MAP process of fresh vegetables. The system was divided into three physical layers: field devices, remote terminal unit (RTU) and master terminal unit (MTU). For packaging width adjuster system, the R2, maximum error (ME), mean absolute error (MAE) and root mean square error (RMSE) were obtained as 0.999, 8 mm, 2.96 mm and 3.44 mm, respectively. For packaging height adjuster system, the R2, ME, MAE and RMSE were obtained as 0.994, 10 mm, 3.53 mm and 4.57 mm, respectively. The SCADA system can be able to accurately adjust the speed of the conveyor and the temperature of the sealing jaws, based on the desired values. For gas injection unit, the value of 1.66 L/min, 0.557 L/min and 0.667 L/min were recorded for ME, MAE and RMSE, respectively. Four types of trends including temperature, speed, flow and digital parameter trends were designed. In addition to displaying screen alarms, the occurred alarms are stored, automatically as a text file for troubleshooting. Finally, the results showed that the designed system can be reliably used for MAP of various varieties of fresh vegetables.

Control Method of Seamless Transfer from Grid-Connected Mode to Isolated Mode for Microgrid Demonstration

It’s easy to cause transient oscillation problems when the microgrid transfers from the grid-connected mode to the isolated mode, so a control method of seamless transfers from the grid-connected mode to the isolated mode for microgrid demonstration is proposed. The switching control strategy of the outer loop controller for the master unit(s) makes the reference value of the current inner-loop controller the same when the microgrid transfers to isolated mode. While the switching control strategy of phase locked loop (PLL) uses an ample-hold assign the output angle of grid-connected PLL to the oscillator adopted by the microgrid in isolated mode at the switching moment. Finally, the sub-regional control strategy uses different control strategies to reserve more spinning capacity for the master unit(s) which divides the power balance into 3 regions. At last, the simulation is verified that the proposed control method not only realizes the seamless transfer from grid-connected operation to islanded operation for the microgrid but also improves the anti-disturbance ability of the microgrid in isolated mode.

Design, Development and Testing of a Monitoring System for the Study of Proton Exchange Fuel Cells and Stacks.

This article is about the design, development and validation of a new monitoring architecture for individual cells and stacks to facilitate the study of proton exchange fuel cells. The system consists of four main elements: input signals, signal processing boards, analogue-to-digital converters (ADCs) and a master terminal unit (MTU). The latter integrates a high-level graphic user interface (GUI) software developed by National Instruments LABVIEW, while the ADCs are based on three digital acquisition units (DAQs). Graphs showing the temperature, currents and voltages in individual cells as well as stacks are integrated for ease of reference. The system validation was carried out both in static and dynamic modes of operation using a Ballard Nexa 1.2 kW fuel cell fed by a hydrogen cylinder, with a Prodigit 32612 electronic load at the output. The system was able to measure the voltage distributions of individual cells, and temperatures at different equidistant points of the stack both with and without an external load, validating its use as an indispensable tool for the study and characterization of these systems.

Solar powered wireless water quality monitoring system for ornamental fish

Ornamental fish have become a popular pet choice due to their convenience and attractiveness. In order to protect the growth and health of ornamental fish and timely improve the water quality conditions, a solar powered wireless water quality monitoring system for ornamental fish was proposed and developed. The system includes the solar power supply module, sensing module and master control module. The solar power supply module includes the solar panel with solar power management module. The sensing module includes the pH and temperature sensor and the master control unit module includes the microprocessor, data remote transmission unit and the organic light-emitting diode (OLED) screen display. The system sustainability performance, sensing performance, and the system evaluation of the solar powered wireless monitoring system for water quality were analyzed and evaluated. The system could effectively acquire the pH and temperature sensor data in water by solar energy powering and wirelessly transmit to the remote monitoring devices such as the smart phone by WiFi or Bluetooth. The proposed system has a potential application example for many kinds of water quality monitoring by renewable energy harvesting to improve the sustainability and quality.

MODIFICATION OF THE MASTER GENERATOR METHOD USED FOR FREQUENCY AND VOLTAGE CONTROL IN ISOLATED POWER SYSTEMS WITH PARALLEL OPERATING AC GENERATORS

Such methods as droop method, curve shifting method and master-slave method were primarily developed for voltage and frequency regulation in isolated power systems with synchronous generators. In modern power systems induction generators, regulated dump loads, energy storage devices with AC/DC and AC/DC/AC power converters, etc. are used in addition to synchronous generators. The investigation of new configurations of power systems is closely tied with further development of control methods for load sharing and regulation of voltage and frequency of the systems. The article reviews simple-to-implement known control methods used for control of isolated power systems with parallel operated synchronous generators and proposes a modification of the master-slave method for control of power systems with parallel operated synchronous and induction generators, static var compensators, dump loads and energy storage devices with interface power converters. The system “Hydroelectric unit with a synchronous generator - dump load - hydroelectric unit with an induction generator - compensating capacitors - transformer – AC local load" is considered and two techniques for regulation of electric frequency and voltage magnitude in the specified system are presented with accordance to the statements of the proposed modified method. The proposed control algorithm of the dump load frequency controller is in agreement with the control algorithm of the speed controller of the master unit. The functions assigned to the electronic PID speed controller of the master unit are to maintain the electric frequency in the system equal to nominal value and regulate the active power sharing. Verification of the proposed control algorithms for isolated electric power systems was carried out. References 23, figures 5, table 1.

A Novel State-of-Charge-Based Droop Control for Battery Energy Storage Systems to Support Coordinated Operation of DC Microgrids

A modern dc microgrid often comprises renewable energy sources (RESs), such as photovoltaic (PV) generation units, battery energy storage systems (BESSs), and local load, and it is also connected to the utility grid through a point of common coupling (PCC). While most existing approaches have to rely on communication links to achieve the desired control performance, this article proposes a novel control strategy without resorting to the communication links. This is achieved by assigning BESSs as master units and regulating the dc bus voltage with a novel state-of-charge (SoC)-based droop control, where the BESSs coordinate the slave units (e.g., RES and utility grid) with the aid of the dc bus signaling (DBS) technique to avoid overcharging and overdischarging of these BESSs. In the proposed droop control, the reference voltage for these BESSs is designed for coordinated operation between BESSs and utility grid, and it is maintained constant in the normal SoC range, which can reduce dc voltage variation. Droop coefficients designed for SoC balance of BESSs are dynamically adjusted based on their own SoC values. Furthermore, the preset maximum deviation between the reference voltage and the dc bus voltage ensures the reliable coordinated operation. Real-time hardware-in-loop (HIL) tests considering three different scenarios are conducted to validate the effectiveness of the proposed method.

Analysis of Steady State Availability of a Series– Parallel Repairable System with Hot Standbys, Three Units and Vacation

Abstract: In this paper we analyze the steady state availability of a series-parallel repairable system. In this system, the first unit is master control unit and other two are slave units and one single repairman who operates single vacation. Under that assumption each unit has arbitrary repair time distribution & a constant failure rate. Also, it is noted that to calculate the availability of the system it is required to obtain the explicit expression and for obtaining steady-state probabilities it is necessary to use “the supplementary variable” method as well as “Markov process theory”.

Application of a Control Algorithm for the Master Unit of a Distributed Photovoltaic System

Application of a Control Algorithm for the Master Unit of a Distributed Photovoltaic System

Математическая модель задатчика перемещения электропривода и разработка его программного обеспечения

Various computational algorithms to perform automatic control of motion are widely used in microprocessor control systems of electric drives. The requirements for such algorithms are the minimum execution time, the minimum amount of calculations, the compactness of the software, the convergence in the statics and dynamics of the control system. It ensures the stability and accuracy of coordinates control. The above-mentioned issues are applicable to the computational algorithm to develop a S-shaped trajectory of the electric drive by the position master unit. The position master unit based on the well-known mathematical model has some disadvantages that limit its use. They are incorrect calculation of the trajectory depending on the speed, acceleration, and sampling interval, as well as the self-oscillatory processes in case of the output and intermediate coordinates. As a result, it leads to a decrease of the accuracy of the electric drive control. Despite the standard solutions, such position master unit require improvement. In this regard, upgrading such a position master unit is relevant. The aim of upgrading is to eliminate these shortcomings by introducing corrective calculations and logical sequences that transfer the position master unit into a stable state as soon as it reaches a given value of the output coordinate. To control the motion of the electric drive when we develop a mathematical model and software based on it, it is necessary to use computational algorithms and numerical methods of calculation that are the least costly in terms of execution time. A modernized mathematical model of the S-shaped trajectory of position master unit is proposed. Restrictions of the parameters of this master unit have been eliminated. They may lead to incorrect path generation, as well as self-oscillations of the output and intermediate coordinates during the path generation, which reduces the accuracy of the electric drive control and cause vibration and noise. The software of the modernized position master unit, in comparison with its original form, does not contain cumbersome arithmetic that is costly in terms of execution time. The software has been successfully implemented into the microprocessor control system of the electric drive. At the same time, it is necessary to observe a time-stable execution of computational sequences and to consider the influence of the values of the numerical parameters used in the calculations.

Emotional Intelligence and Work Commitment of Public School Administrators

Purpose: This study investigated the emotional intelligence and work commitment levels of public school administrators (elementary and secondary) in the districts of Candijay, Alicia, Mabini, Anda, and Guindulman (CAMAG), Division of Bohol, for the School Year 2018 – 2019, with the end view of proposing recommendations. Approach/Methodology/Design: Data from 49 participants on emotional intelligence and work commitment are extracted using Schutte Intelligence Scale or Assessing Emotions Scale and Meyer and Allen's Three Commitment Model (TCM) Questionnaire. It espoused a descriptive-correlational research design with the aid of standardized tools. Findings: Results showed that females dominated among the respondents, wherein most of them obtained only a few Master's units. All dimensions of emotional intelligence were rated "Very High," and in general, they obtained "Very High" emotional intelligence level. The research participants have very high affective, continuance, and normative commitment levels. Overall, they possess a "Very High" commitment level. On the other hand, the respondents’ demographic profile (as to age, sex, civil status, highest educational attainment, and length of service as administrator) did not correlate with their emotional intelligence and work commitment levels. Furthermore, a correlation exists between emotional intelligence and work commitment, which implies that emotional intelligence is a determinant of their work commitment. Provident recommendations were given to address the studied phenomenon. Practical Implications: The study aimed to explore if emotional intelligence is a predictor of work commitment. Originality/value: This study investigates the level of intelligence and work commitment of public school administrators.

Application of Improved Robot-assisted Laparoscopic Telesurgery with 5G Technology in Urology

The demand for telesurgery is rising rapidly, but robust evidence regarding the feasibility of its application in urology is still rare. From March to October 2021, a surgeon-controlled surgical robot in a tertiary hospital in Qingdao was used to remotely conduct robot-assisted laparoscopic radical nephrectomy (RN) in 29 patients located in eight primary hospitals. The median round-trip delay was 26 ms (interquartile range [IQR] 5) and the median distance between the primary hospital and the surgeon was 187 km (IQR 57). Both the master unit and the slave unit were guaranteed by network and mechanical engineers, and surgical assistants were well prepared on the patient side to prevent complications. The primary evaluation metric was the success rate, defined as the percentage of patients who underwent successful remote RN without conversion to other surgical procedures and no major intraoperative or postoperative complications. The results demonstrate that the combination of 5G technology and surgical robots is a novel potential telemedicine-based therapy choice for renal tumors. Patient summaryOur study shows that telesurgery using 5G technology is a safe and feasible treatment option for patients with kidney tumors. The total delay between the remote location and the operating rooms where surgery was being performed was just 200 ms. This approach could reduce health care costs and improve the quality of medical services accessed by patients.