This study assesses short-term and long-term learning outcomes of Question, Persuade, Refer (QPR) suicide prevention training in a college setting. Two hundred seventy-three participants completed ...pretest, posttest, and follow-up surveys regarding suicide prevention knowledge, attitudes, and skills. Results indicated: (a) increases in suicide prevention knowledge, attitudes, and skills both from the pretest to the posttest and from the pretest to the follow-up test on 8 items (warning signs, how to ask about suicide, influencing help-seeking, how to get help, knowledge of local resources, talking about resources, accompanying person to get help, and calling a crisis line); and (b) short-term increases on 2 items (suicide prevention facts and appropriateness of asking about suicide). Implications for campus-wide suicide prevention efforts are discussed.
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BFBNIB, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Hybrid distribution transformer (HDT) has powerful control ability, which is significant for the intelligentisation of the distribution network. A kind of HDT is presented here, the grid current ...control system of which is emphatic researched. Based on the mathematical model of ideal HDTs, a grid current control system is designed with quasi proportional-resonant controller (QPR). Using the characteristics that infinite gain and large bandwidth at the resonant frequency of QPR controller, the grid current system achieve the effects of unit power factor and sinusoidal symmetrical waveform. Tracking control with no static error of grid current was achieved in MATLAB. Compared with the traditional PI control, QPR controller can modulate AC signals in the static coordinate system, rather than rotary coordinate system. So the QPR controller has advantages of lower steady-state error, stronger anti-interference ability, and simpler calculation. Simulation results show that it has good dynamic and steady performance.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A novel control strategy DPLL-QPR (Digital Phase-Locked-Loop and Quasi Proportional-Resonant) of current closed-loop for AC electrical load is proposed to implement a low-cost, fast and accurate ...control system. The closed-loop model analysis and the design of this control strategy of the system are presented in this paper. MATLAB is employed to analyze and optimize the parameters for digital controller. At last, a 100VA prototype has been built and tested to verify the theoretical analysis of the paper.
For the grid-connected process of photovoltaic power generation, the grid-connected inverter is much more important. The current control strategy plays a significant role in the normal operation of ...the entire inverter and the system, as well as in the coordination and cooperation with other parts. On account of this, study the operating condition of the inverter with different current control strategies is of great significance. In this article, by establishing mathematical models, control performance of inverters with different current controllers is compared, which include the PI controller, the PR controller and the QPR controller. On the one hand, through theoretical derivation, the analysis proves that comparing to the traditional PI controller and ordinary PR controller, the QPR controller can not only realize zero error tracking, but also can follow the given waveform with no static difference near the fundamental wave and the gain will not be too high, making the system more stable. On the other hand, the simulation operation in MATLAB/Simulink compares the control effect of PR controller and QPR controller, and proves that the latter has better performance.
Suicide prevention training programs have spread rapidly within child and public-serving organizations, due to the alarming increase in youth suicide rates. Yet, within these organizations, roles and ...responsibilities can shape attitudes and intentions related to suicide prevention, thereby influencing the uptake of prevention efforts. As such, various organizational and individual factors can predict uptake, adoption, and maintenance of prevention efforts (Fixsen et al.,
2005
). To date, few studies have examined the service delivery context in understanding training effectiveness, especially as it relates to QPR (Question Persuade and Refer), one of the most widely disseminated suicide prevention gatekeeper programs. The purpose of this longitudinal study was to evaluate whether individual and organizational characteristics influenced the effectiveness and sustainability of training outcomes, and whether such differences existed among diverse child and public-serving delivery sectors. Several training outcomes that align with the Theory of Planned Behavior (Ajzen,
1991
) were examined, including confidence, attitudes, social norms, and suicide prevention behaviors. Measures were assessed prior to and 90 days after the QPR program among a sample of 858 professionals. Community support personnel uniquely showed improvements on social norms while juvenile justice and child welfare workers engaged in more suicide prevention behaviors post training. While trainees across sectors had improved suicide prevention attitudes, law enforcement personnel were the exception. Organizational climate predicted change in suicide prevention attitudes, confidence, and social norms. Trainees who were older, Latinx, and Black had the most improvement on several training outcome variables, but these findings also varied within service sectors.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This paper presents an approach for sensorless speed control of Permanent Magnet Synchronous Machines (PMSMs) for Electric Vehicles (EVs) using a Sliding Mode Ob-server (SMO). In vector control, ...position and speed encoders are indispensable for closed-loop control. However, mechanical sensors are highly susceptible to failure and necessitate considerable space and circuitry, ultimately leading to an increase in cost. The paper proposes sensorless speed control techniques for PMSM- driven EVs. The conventional SMO suffers from challenges such as chattering and phase delay due to its discontinuous function and the inclusion of a low-pass filter (LPF). A Quasi Proportional Resonant (QPR) based observer is introduced to mitigate these issues. By appropriately selecting the resonance frequency of the QPR controller, it is possible to eliminate the sign function and LPF in the conventional SMO. In this paper, the sign function of the conventional SMO is replaced with a QPR controller-based observer to improve performance. Simulation results demonstrate the superior performance of the proposed method compared to the conventional SMO.
Research On Eenergy Feedback Type AC Electronic Load Xie, Xinyao; Fan, Lingyu; Ning, Yifan ...
2023 International Seminar on Computer Science and Engineering Technology (SCSET),
2023-April
Conference Proceeding
The study of AC electronic load for student learning and power testing proposed an energy feedback type AC electronic load. Energy feedback single phase AC electronic load is a power electronic ...device which can simulate resistive load and inductive and capacitive load of any power factor and return the absorbed energy to the power grid. The main circuit topology adopts AC/DC/AC structure, the former load characteristic simulation unit adopts the current loop closed-loop control, the latter stage energy feedback unit adopts the double closed-loop grid-connected control algorithm, and the main circuit rectifier and inverter adopt the unipolar PWM modulation scheme.
Large grid impedance is the main characteristic of weak grid, and its accurate detection can improve the inverter control performance. However, traditional impedance detection method based on current ...harmonic injection usually causes a large increase in harmonics, which weakens the power quality. In order to solve this problem, an improved multiple harmonic injection method based on QPR (Quasi Proportional Resonance) parameter-adaptive control strategy is proposed in this paper. By analyzing the impedance detection results and the power quality of the inverter output, the impedance detection results are sent to the adaptive control system, which is used to correct the quality of the grid-connected current waveform after calculating each parameter of the QPR controller. The final simulation results show that the proposed improved control strategy can improve the inverter output waveform quality and enhance the anti-interference capability of the weak grid without changing the impedance detection accuracy of the wind power grid-connected inverter under weak power conditions.
The mathematical model of three-phase LCL inverter has coupling term in dq coordinate system. At the same time, the traditional proportional integrate (PI) controller can only realize the no ...steady-state error control of the sinusoidal AC current in dq coordinate system. This requires highly accurate phase angles and complex coordinate transformations. This paper proposes a control strategy which uses the Quasi-proportional resonant (QPR) controller in the αβ coordinate system. Using the capacitor current as the inner loop realizes active damping and inhibits the resonance peak of LCL filter. The grid-connected current external loop control sine AC current non-static tracking. Design capacitance current feedback coefficient, the proportional coefficient of QPR controller and resonance gain coefficient with frequency domain analysis and zero-pole assignment. The parameter design method and the effectiveness of the control strategy are proved in the simulation and experiment.
Aiming at the problems of difficult control of traditional voltage-type AC electronic load, poor dynamic response, and large voltage stress of the downstream power devices, a control strategy of ...current-type energy-fed AC electronic load is proposed. It adopts dual PWM back-to-back structure, and the front load simulator adopts independent dual-loop control of fuzzy PI control DC current and QPR control AC current. The outer loop of the downstream grid-connected inverter realizes the power balance between the front and rear stages of the system by PI control of the error between the given power and the actual power. The inner loop uses the PI+ repeated control method to track the amplitude and phase of the grid-connected current. The comprehensive control strategy is adopted to finally realize the functions of load simulation, energy feed network, and power balance of AC electronic loads. This solution has the advantages of simple controller design and high realizability. Through Matlab/Smiulink simulation and building an experimental platform, the simulation and experimental results verify the correctness of the theory.
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