Unpredictable Parameter Research Articles

A Sliding-Mode Control with Efficient Chattering Alleviation for Single-Phase Voltage Source Inverters

This paper presents an adaptive sliding mode control (SMC) method with a variable boundary layer for single-phase voltage source inverters. This strategy offers a very simple sliding function without any derivative term while preserving unique characteristics of the sliding mode control like fast dynamic response and robustness against parameter variations while also possessing the variable boundary layer method to reject the chattering phenomena. Chattering excites the high frequencies in the system and leads to inaccuracy and instability. It is shown that despite the conventinal approches, the proposed variable boundary layer method can both alleviate the chattering and generating the minimum steady state error. Owing to the adaptive nature of the suggested control approach which adjusts the thickness of the boundary layer, the whole mechanism can be controlled successfully under unpredictable parameter variations. The accomplishment of the suggested strategy is investigated by simulations in MATLAB/Simulink. The outcomes are compared with the outcomes obtained without boundary layer, with constant boundary layer and super twisting sliding control methods. The comparison reveals that the proposed control technique outperforms the other control methods for the voltage source inverter. The results demonstrate that while the conventional, SMC with constant boundary layer and super twisting sliding control (STSMC) methods have 50% ,8% and 10% chattering over their control input respectively, the proposed method has less than 3% chattering over the control input.

Morphometric topography of the left atrial appendage in human adult heart

Topography of the left atrial appendage is of importance for supraventricular arrhythmias surgery and sealing of the appendage orifice to prevent thromboembolism in cryptogenic strokes. The aim was to explore the common position of the appendage and delineate variants of its adjacent anatomy in human adults by means cadaveric morphometrics. Material and methods . We studied 54 silicone-filled heart specimens of 200–400 g. With the caliper, we measured the distances from the base of the left atrial appendage to the cardiac apex, to the structures of the atrial complex, nearest large blood vessels, as well as to the left coronary artery. Results. The base of the appendage was 87 ± 13.1 mm from the cardiac apex and 49.7 ± 7.0 mm from the right appendage. The distance from the appendage to the superior caval vein (36.4 ± 8.1 mm) was 16 % longer than the distance to the ascending aorta (30.4 ± 6.4 mm), 1.25 times less than the distance to the oval fossa (45.2 ± 6.0 mm), 1.5 times less than the distance to the inferior caval vein (55.5 ± 8.7). The smallest median value (9.6 mm) and the largest variation (1.4–15.2 mm) were found for the distance to the pulmonary trunk. Four pulmonary veins inflowed to the atrium at different distances from the appendage opening. In 59.6 %, we revealed the left upper pulmonary vein to be closest to the auricle. The mouth of that was 43 % higher and 57 % at the same level with the appendage opening ( p = 0.07). The left coronary artery ran 2.63–18.74 mm inferiorly to the appendage. Interrelations of average strength were found for the parameters of atrial complex. The study showed the length of the ventricular complex as being an unpredictable parameter for determining the adjacent anatomy of left atrial appendage. Conclusions. The morphometric parameters and their interrelations are proposed to use as reference values and criteria for determining the normal atrial complex.

Fuzzy Logic based Anti-Slip Control of Commuter Train with FPGA Implementation

In the railway industry, slip control has always been essential due to the low friction and low adhesion between the wheels and the rail and has been an issue for the design, activity, and operation of railroad vehicles. Slip is an unpredictable parameter in the railroad that disintegrates the surface of the railroad with a contact surface of the boggy wheel brought about by the mechanical force of traction phenomena, it destabilizes the railway traction which does not fulfill safety and punctuality requirements. In this paper, we present the work based on developing a fuzzy logic-based anti-slip controller for the commuter train using FPGA implementation which minimizes slip parameters. The development of a fuzzy logic-based anti-slip controller for the commuter train is designed in MATLAB and then tested for area-performance parameters in FPGA through the system generator library. Simulation is performed to demonstrate the effectiveness of the proposed fuzzy logic control system for anti-slip control under various parameters, the results of simulation prove the effectiveness of the proposed control system as compared with conventional PID controller and shows high anti-slip control performance under nonlinearity of brake dynamics.

Study on Fuzzy Multiple Reference Model Adaptive Control Strategies

A new fuzzy multiple reference model adaptive control method combined with fuzzy select and conventional adaptive control is presented. To overcome the control difficulties which due to significant and unpredictable system parameter variations, fuzzy logic rules are designed to choose the suitable reference model. The new method is applied to control the speed servo system of dynamic model of BLDCM, and the simulation results show it works well with high dynamic performance and control precision under the condition of great change in reference speed and load torque.

Forensic Engineering and the Importance of the Human Factor

Forensic engineering and its significance from the perspective of history, its importance in the interdisciplinary context. Disciplines involved with their findings in expert assessment. Questions of expert activities at present. Technical and legislative aspects of expert activities. Personality factors in expert activities and their reflection in expert assessment. The influence of human factor involved in the causes giving rise to exposed situations which entail the origin of expert assessment. The importance of personality factors. Assessment of the reliability of the human factor, i.e. the probability of correctly performing the required activities during a given period of time or a situation which may give rise to chain reactions that lead to mistakes of human factor. Human reliability, or more precisely human mistakes as a very complex and unpredictable parameter. When assessing it, it is therefore necessary to understand the fact that this is not an isolated step or a single decision, but a set of causes, influences and factors (including their mutual combinations) that make up the overall reliability.Possibilities of applying forensic engineering into practice. Defects of expert assessment and their consequences. The most common and the most recent faults occurring in expert assessment.

Mathematical Model for Supply Planning of Multi-level Assembly Systems with Stochastic Lead Times

The deal for industrial companies is to satisfy their customers with the best quality, the most reliable lead times, and the lowest costs. One of the keys to achieve it is in the inventory control in the Supply Chain. Moreover, it is mandatory to possess necessary components in order to produce the requested products by the due date. But, as the components lead time is an unpredictable parameter, it is difficult to take it into account correctly. The paper deals with this question considering that each component has a fixed unit inventory cost; the finished product has an inventory cost and a backlogging cost per unit of time. Then, a general mathematical model for supply planning of multilevel assembly system is presented to calculate the expected value of the total cost which equals to the sum of the inventory holding costs for the components, the backlogging and the inventory holding costs for the finished product.

Predictive Functional Control for the Induction Motors Based on FOC

Abstract The control system of induction motor used in EV is studied in this paper. The new PFC controller based on rotor flux field-oriented vector control is designed in order to overcome the effects of uncertainties of unpredictable parameter variations and external load disturbances. The SVPWM control strategy is used to realize high-efficient control scheme. The simulation and experiment results indicate that the PFC algorithm can achieve better dynamic and static properties and stronger robustness than the conventional PI controller, and can track the given trajectory primly. It is well suited for electric-driven system.

Fuzzy Multiple Reference Models Adaptive Control of Induction Motors

A new method of fuzzy multiple reference models adaptive control(FMRMAC) for dealing with significant and unpredictable system parameter variations is presented. In this method, different suitable reference model is chosen by fuzzy rules when changes occurred to the model parameters. A successful application to the speed servo system of dynamic model of induction motor (IM) shows this method works well with high dynamic performance under the condition of command speed change and load torque disturbance.

RLSN 예측기 기반 섭동 추정기를 갖는 슬라이딩 모드 제어

This paper presents the sliding mode control with the perturbation estimator for a nonlinear control system in the presence of perturbations including external disturbances, unpredictable parameter variations, and unstructured dynamics. The proposed perturbation estimator is based on the Recursive Linear Smoothed Newton predictive algorithm so that it is effective to attenuate an undesired noise in high frequency band and to predict the present perturbation signal from the previous ones. Compared to conventional sliding mode control (SMC) and sliding mode control with perturbation estimation (SMCPE) introduced by Elmali and Olgac, the control algorithm proposed in this study can offer better tracking control performances and more feasible estimation characteristics. The effectiveness and superiority of the proposed control strategy are demonstrated by a series of simulations on the position tracking control of a simple two-link robot manipulator subject to velocity feedback signals including white noises.

On the detectability of CMOS floating gate transistor faults

This paper focuses on the detectability of defects causing the gates of transistors in CMOS integrated circuits to float (open), i.e., on floating gate transistor (FGT) faults. Such faults are known to occur in practice. It is increasingly important to consider their detection to meet high quality requirements for circuits fabricated in deep submicrometer technologies. We focus on the detectability of FGT faults by the standard voltage- and current-based production test strategies that we refer to as static voltage (SV), dynamic voltage (DV), and static current (SC) test strategies. We demonstrate how the behavior of the devices caused by FGT faults depends on two classes of technological and topological parameters: the predictable and unpredictable parameters. We show that an FGT fault can induce abnormal logic values, additional delays, or increased power supply current. We introduce the concept of a detectability interval, i.e., the range of values an unpredictable parameter may assume that one allows for the fault detection using a specific test strategy. We illustrate how the detectability intervals for the SV and DV strategies complement that of the SC strategy. In addition, a new test scheme that results in an increased SC detectability of FGT faults is developed. Finally, we demonstrate the effects of initial trapped charges and the effects of coupling to surrounding metal on the detectability intervals of each of the test strategies.

Distributed fuzzy control of flexible manufacturing systems

A flexible manufacturing system (FMS) consists of a set of machines that are connected via tracks over which parts may be transported from one machine to another for processing. As parts arrive at a machine via the tracks, they are put in a buffer (queue) where they are held before they are processed. There is a local controller (scheduling policy) at each machine which uses the machine's buffer levels to decide which part type to process next; hence the overall controller for the FMS is physically distributed across the entire FMS with local schedulers at each machine. In this paper the authors show how to design a fuzzy controller for a single machine and show via simulation that its performance is comparable to conventional schedulers. In addition, the authors introduce an adaptive fuzzy controller which can automatically synthesize itself (or tune itself if there are machine parameter variations) to achieve good throughput rates for the single machine as compared with conventional schedulers. Next it is shown via simulations that by using such adaptive fuzzy controllers in a distributed fashion, one obtains a distributed fuzzy controller (DFC) which can automatically synthesize itself and lower the maximum buffer level more effectively than conventional schedulers. Finally, the authors illustrate the ability of the DFC and conventional schedulers to automatically tune themselves in case there are unpredictable machine parameter changes in an FMS. These final results show that while sometimes the DFC performs in a superior fashion, better scheduling policies are needed to guarantee high performance FMS operation in case there are unpredictable machine parameter changes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Proposal for Estimation of Soil Leaching and Leaching Constants for Use in Assessment Models

AbstractA model to predict annual‐average, order‐of‐magnitude leaching constants for solutes in agricultural soils is given. The leaching constants, specific by geographic location and solute, are for use in exposure, dose, or risk assessment models to account for removal from the root zone via leaching in a manner analogous to radiological decay. The model presented here relates annual‐average water infiltration (Vw) with soil bulk density (ϱ) and porosity (θ) and the distribution coefficient (Kd) for the solute. Annual infiltration is determined from site‐specific estimates of total precipitation (P), irrigation (I), and evapotranspiration (E). A review, discussion, and determination of generic default model input parameters is included. The parameters ϱ and θ vary within a factor of three, and are lognormally distributed with estimated geometric mean values of 1.35 g cm−3 and 0.48 cm3 cm−3, respectively. Geographic distributions of U.S. county‐averaged P, I, and E were determined from historical weather station records, the 1974 Agricultural Census, and an evapotranspiration model, respectively. Variability in site‐specific annual‐average estimates of these parameters is expected to be within a factor of three, also. The most variable and unpredictable parameter is Kd, which may range from one to many orders of magnitude, depending on solute and soil characteristics, including pH. Estimated distributions of Kd for 27 elements in soils 4.5 ≤ pH ≤ 9.0, and correlations between Kd and pH for Cu, Zn, Cd, and Pb are also included. Finally, eight comparisons of model predictions with leaching constants, determined directly from observed data, are made for Pu, Sr, and Tc. In all comparisons, except one study of Pu, the model predicted leaching constants within an order of magnitude of observed values. For Pu the model underpredicted, and for Sr and Tc the model overpredicted leaching rates.