Practical Control Method Research Articles

A Practical Quality Control Method for Saponins Without UV Absorption by UPLC-QDA.

Saponins are a class of important active ingredients. Analysis of saponin-containing herbal medicines is a major challenge for the quality control of medicinal herbs in companies. Taking the medicine Astragali radix (AR) as an example, it has been shown that the existing evaporative light scattering detection (ELSD) methods of astragaloside IV (AG IV) has the disadvantages of time-consuming sample preparation and low sensitivity. The universality of ELSD results in an inapplicable fingerprint with huge signals from primary compounds and smaller signals from saponins. The purpose of this study was to provide a practical and comprehensive method for the quality control of the astragalosides in AR. A simple sample preparation method with sonication extraction and ammonia hydrolyzation was established, which shortens the preparation time from around 2 days to less than 2 h. A UPLC-QDA method with the SIM mode was established for the quantification of AG IV in AR. Methanol extract was subjected to UPLC-QDA for fingerprinting analysis, and the common peaks were assigned simultaneously with the QDA. The results showed that with the newly established method, the preparation time for a set of samples was less than 90 min. The fingerprints can simultaneously detect both saponins and flavonoids in AR. This simple, rapid, and comprehensive UPLC-QDA method is suitable for quality assessment of RA and its products in companies, and also provides references for the quality control of other saponin ingredients without UV absorption.

Development of a Tele-Operated Rescue Robot for a Disaster Response

This paper proposes practical hardware design strategies and control methods for a rescue robot to save patients in disastrous environments. None of the existing humanoid robots have not shown the capability to efficiently execute rescue tasks for transferring a human to a safe place in a highly unstructured world. To resolve this problem a new form of powerful dual arm mechanism and hybrid tracked-legged mobile platform is developed and the motion is synthesized with dynamics based optimization and a modified hierarchical control scheme. These new design and control policies enable us to simultaneously enhance the manipulation performance and driving stability which have been verified through both in extensive numerical simulations and physical experiments where the rescue robot and whole-body control are indeed required.

Anti-windup disturbance feedback control: Practical design with robustness

This paper presents a practical design method of robust disturbance feedback control (DFC) along with an application to industrial refrigeration systems. DFC is a controller configuration in which an existing controller is augmented with an additional loop. The design method for DFC is proposed in two steps; firstly, the robust DFC without saturation is designed by a linear matrix inequality (LMI) approach, and then LMI techniques are used again for designing an anti-windup compensator to accommodate actuator saturation. The proposed method is compared to a conventional design on a water chiller system, both in simulation and through practical experiments. The test results indicate that both robustness and performance can be improved in the presence of model uncertainties, and the proposed method can avoid wind-up phenomena when the control inputs are saturated.

Robust and adaptive dynamic controller for fully-actuated robots in operational space under uncertainties

A practical control method that can perform multiple tasks in operational space is proposed for a fully actuated robot with high kinematic redundancy. Its dynamic control is often realized through force-level operational-space control framework, which computes joint torques for the required forces of prioritized multiple tasks. This approach requires an accurate dynamic model that is a major hurdle to overcome for implementation in real robots. To exempt from complex and demanding inverse dynamics computations, the proposed controller incorporates adaptive sliding-mode and online dynamics estimation schemes. The proposed operational space controller has two merits: it can obtain highly accurate control performance without calculating complex robot dynamics, and it can adapt the control parameters online to effectively compensate the uncertainties when the posture of a humanoid robot is substantially changed during operation; thus, a relatively simple, adaptive and robust control is realized for practical use for a kinematically redundant robots in operational space. The effectiveness of the proposed control method is numerically validated using a dynamic simulator. The simulated scenarios include that a fully-actuated humanoid robot undergoes severe changes in its inertia with respect to changes in posture. Experiments with a 23 degrees-of-freedom torque-controlled humanoid, CoMan, verify that the controller can perform three multiple operational-space tasks under uncertain external disturbances with high accuracy.

Linking fish tolerance to water quality criteria for the assessment of environmental flows: A practical method for streamflow regulation and pollution control

The survival of aquatic biota in stream ecosystems depends on both water quantity and quality, and is particularly susceptible to degraded water quality in regulated rivers. Maintenance of environmental flows (e-flows) for aquatic biota with optimum water quantity and quality is essential for sustainable ecosystem services, especially in developing regions with insufficient stream monitoring of hydrology, water quality and aquatic biota. Few e-flow methods are available that closely link aquatic biota tolerances to pollutant concentrations in a simple and practical manner. In this paper a new method was proposed to assess e-flows that aimed to satisfy the requirements of aquatic biota for both the quantity and quality of the streamflow by linking fish tolerances to water quality criteria, or the allowable concentration of pollutants. For better operation of water projects and control of pollutants discharged into streams, this paper presented two coefficients for streamflow adjustment and pollutant control. Assessment of e-flows in the Wei River, the largest tributary of the Yellow River, shows that streamflow in dry seasons failed to meet e-flow requirements. Pollutant influx exerted a large pressure on the aquatic ecosystem, with pollutant concentrations much higher than that of the fish tolerance thresholds. We found that both flow velocity and water temperature exerted great influences on the pollutant degradation rate. Flow velocity had a much greater influence on pollutant degradation than did the standard deviation of flow velocity. This study provides new methods to closely link the tolerance of aquatic biota to water quality criteria for e-flow assessment. The recommended coefficients for streamflow adjustment and pollutant control, to dynamically regulate streamflow and control pollutant discharge, are helpful for river management and ecosystems rehabilitation. The relatively low data requirement also makes the method easy to use efficiently in developing regions, and thus this study has significant implications for managing flows in polluted and regulated rivers worldwide.

Research of Intersection Traffic Signal Control and Simulation Based on Fuzzy Logic

In order to improve the traffic signal control for urban road intersection and reduce vehicle delay, the paper took the typical urban crossing signal control system as the research object and proposed a control algorithm based on fuzzy logic. Considering the traffic flow information as well as the length of vehicles on different approaches, the average delay hours had been selected out as the performance index. By using the control algorithm to improve the traditional fixed cycle length time distribution method of the intersection, the paper successfully designed a signal control system to adapt to various traffic conditions. By using Matlab software to analyze the data and simulate the effect, the results showed that this algorithm significantly reduced the traffic delay, achieved good control effect, and enhanced the capacity of the intersection. It has proved that the utilization of the control algorithm is a practical and effective method for the intelligent urban traffic control.

Recent topics of candidate antigens for immunological control of ixodid ticks

Ticks have been recognized as harmful parasite since ancient times. At present immunological protection of host against ticks is the most practical and sustainable tick control method, which is more suitable to natural environment compared to the current use of acaricides. Recently, focuses on the development of anti-tick vaccine are the identification, molecular cloning and in vitro production of recombinant protein, responsible for executing key roles in regulating physiology, modulation of host immune response and pathogen transmission via ticks. Among several works, serine protease inhibitors have been thought as one of the most interest vaccine candidates, because serine protease inhibitors are mainly involved in the maintenance of homeostasis. In the current review, we would like to introduce selected examples covering aspects of tick vaccine antigen identification and analyses, because advances in vector molecular biology open new possibilities for vaccine development. In dealing with this subject, contents were mainly divided into tick salivary gland associated molecules (exposed antigens) injected into the host during tick feeding and no salivary gland molecules (concealed antigens). While emerging the fact that serine protease inhibitors belong to either exposed or concealed antigens, the utility of serine protease inhibitors for the candidate vaccine have been discussed separately because of the importance of serine protease inhibitors in the physiology of several organisms including ticks. Advances in tick vaccine development and related subjects are regularly reviewed and in this paper, referred citations of excellence are suggested as additional reading.

Leader-Follower Formation Control of UUVs with Model Uncertainties, Current Disturbances, and Unstable Communication.

Unmanned underwater vehicles (UUVs) have rapidly developed as mobile sensor networks recently in the investigation, survey, and exploration of the underwater environment. The goal of this paper is to develop a practical and efficient formation control method to improve work efficiency of multi-UUV sensor networks. Distributed leader-follower formation controllers are designed based on a state feedback and consensus algorithm. Considering that each vehicle is subject to model uncertainties and current disturbances, a second-order integral UUV model with a nonlinear function is established using the state feedback linearized method under current disturbances. For unstable communication among UUVs, communication failure and acoustic link noise interference are considered. Two-layer random switching communication topologies are proposed to solve the problem of communication failure. For acoustic link noise interference, accurate representation of valid communication information and noise stripping when designing controllers is necessary. Effective communication topology weights are designed to represent the validity of communication information interfered by noise. Utilizing state feedback and noise stripping, sufficient conditions for design formation controllers are proposed to ensure UUV formation achieves consensus under model uncertainties, current disturbances, and unstable communication. The stability of formation controllers is proven by the Lyapunov-Razumikhin theorem, and the validity is verified by simulation results.

A feasible and practical 1H NMR analytical method for the quality control and quantification of bioactive principles in Lycii Fructus

Lycii Fructus, a solanaceous drug, is widely used as functional foods and in Traditional Chinese Medicine. Samples collected from different regions of China have been found to be not identical in chemical compositions which might affect the biological activities. Although many chromatographic and spectrometric methods have been reported to determine the concentration of betaine and other bioactive amino acids, disturbance resulted from other polar substances with low UV-absorbance and expensive mass facilities reduced the applicability of these techniques. In the present study, the strong cation exchange solid phase extraction procedure incorporated with 1H NMR was successfully developed as a rapid and reliable method that can simultaneously determine betaine, citric acid, threonine, alanine, and proline in various Lycii Fructus. In addition, ERETIC 2 method based on PULCON principle was also applied and compared with conventional method. This feasible and practical method offers a very powerful tool for the quality control of commercial Lycii Fructus from different sources.

Invasion of the red-necked longicorn beetle, Aromia bungii : damages of Rosaceae trees and practical control methods

Invasion of the red-necked longicorn beetle, <i>Aromia bungii</i> : damages of Rosaceae trees and practical control methods

Rapid and sensitive liquid chromatography–tandem mass spectrometric method for the quantitative determination of potentially harmful substance 5,5′-oxydimethylenebis (2-furfural) in traditional Chinese medicine injections

With the rapid development and wide application of traditional Chinese medicine injection (TCMI), a number of adverse events of some TCMIs have incessantly been reported and have drawn broad attention in recent years. Establishing effective and practical analytical methods for safety evaluation and quality control of TCMI can help to improve the safety of TCMIs in clinical applications. In this study, a sensitive and rapid high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) method has been developed and validated for the quantitative determination of potentially harmful substance 5,5′-oxydimethylenebis (2-furfural, OMBF) in TCMI samples. Chromatographic separation was performed on a C18 reversed-phase column (150mm×2.1mm, 5µm) by gradient elution, using methanol–water containing 0.1% formic acid as mobile phase at the flow rate of 0.3mL/min. MS/MS detection was performed on a triple quadrupole mass spectrometer with positive electrospray ionization in the multiple reaction-monitoring mode. The method was sensitive with a limit of quantification of 0.3ng/mL and linear over the range of 0.3–30ng/mL (r=0.9998). Intra- and inter-day precision for analyte was <9.52% RSD with recoveries in the range 88.0–109.67% at three concentration levels. The validated method was successfully applied to quantitatively determine the compound OMBF in TCMIs and glucose injections. Our study indicates that this method is simple, sensitive, practicable and reliable, and could be applied for safety evaluation and quality control of TCMIs and glucose injections.

Characterization of pre-treatments on wood chips prior to delignification by near infrared spectroscopy

A near infrared (NIR) spectroscopy-based method for predicting yields and lignin contents of differently pre-treated silver/white birch (Betula pendula/B. pubescens) and Scots pine (Pinus sylvestris) chips was developed. The approach was to create multivariate calibration models from the NIR data by the partial least squares (PLS) method. Both parameters are important factors when adjusting adequate conditions for pre-treatments either with hot-water (HW) as such and slightly acidified HW (collectively referred to as autohydrolysis) or dilute alkaline aqueous solutions prior to alkaline pulping. Pre-treatment conditions were varied with respect to temperature (130 °C and 150 °C) and treatment time (from 30 min to 120 min). In the case of alkaline pre-treatments, the NaOH charge was 1% to 8% NaOH on wood dry solids (DS). The yields varied in the range 81.2% to 99.3% (in autohydrolyses) and 83.5% to 97.9% (in alkaline pre-treatments). High correlation coefficients and low prediction errors in relation to conventional yield and lignin content data clearly indicated the suitability of NIR spectroscopy combined with the multivariate modeling as an effective and fast tool for this purpose. This technique also showed promising possibilities for developing practical process control methods to follow such pre-treatments.

Contouring control of ball screw mechanism using a practical control method

This paper presents an improved practical controller for enhancing the contouring motion of a ball screw mechanism. Practically, a high motion control performance and ease of controller design are desired. A continuous motion nominal characteristic trajectory following (CM NCTF) control has been considered to fulfill the desired performance. The NCTF controller comprises of a nominal characteristic trajectory (NCT) and a PI compensator where the controller parameters are easily determined and it is free from exact modeling. In the present paper, the CM NCTF controller has been proposed in order to enhance the continuous motion performance such as tracking and contouring accuracies of the system. In order to justify the advantages, the CM NCTF controller was examined in tracking motion performances using an AC driven X-Y ball screw mechanism. The bandwidth of the CM NCTF controller is larger compared to the PID controller, therefore, it proved that the CM NCTF controller has fast response as compared with the PID controller. The experimental results proved that the CM NCTF controller achieves better contouring motion performances than the PID controller by showing a two times smaller motion error.

A practical sensorless commutation method based on virtual neutral voltage for brushless DC motor

This paper presents a low‐cost and highly practical sensorless control method for brushless DC (BLDC) motor drives. The developed methodology can generate an accurate commutation signal for the BLDC motor by sensing the back electromotive force zero‐crossing point through the virtual neutral voltage of the motor. Since commutation control is critical for the BLDC motor control, a voltage‐controlled phase shifter comprising a hysteresis comparator and voltage‐controlled resistor is proposed in order to perform phase compensation at different speeds and prevent rapid output oscillations due to noise or high‐frequency ripples in the virtual neutral voltage. Finally, several experiments have been performed on a prototype motor to verify the theoretical analysis and demonstrate the practicality and reliability of the proposed sensorless drive method. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Flashlight contamination and effectiveness of two disinfectants in a stomatology hospital

AimThis study aims to assess the infection risks of flashlight contamination in a stomatology hospital and compare the disinfection effectiveness of alcohol (75%) and disinfecting wipes. BackgroundThe flashlight is a basic non-critical medical device in oral and maxillofacial surgery wards. Wounds are mostly found in oral cavities; therefore, reusable flashlights may be a potential source of nosocomial infections (NIs). However, the microbial flora present in flashlights used in hospitals has not yet been explored. MethodsThis study investigated the microbial contamination of 41 flashlights used in a stomatology hospital in Guangzhou in March 2016. ResultsResults indicated that 75.6%(31/41) of the flashlights had microbial contamination. Gram-positive bacteria accounted for 72.7%(24/33)of the microbial groups contaminating the flashlights, and Gram-negative bacteria (21.2%, 7/33), and fungi (6.1%, 2/33) constituted the remaining contaminants. The predominantly isolated species was Staphyloccus (66.7%, 22/33), especially Staphylococcus aureus (24.2%, 8/33). Approximately 77.3% (17/22) of the types of bacteria detected in the hands were same as those in the corresponding flashlights. Both the bacterial overstandard and S. aureus detection rates of doctors' flashlights were higher than those of nurses' flashlights (16/17 vs. 14/23, 7/17 vs. 1/23, respectively) (P < 0.05). Moreover, both disinfectants performed excellently, and their eligibility rates were not significantly different (17/17 vs. 14/14) (P > 0.05). ConclusionFlashlights are potential causes of NIs. Disinfecting flashlights could be an effective and practical infection control method.

Attitude guidance and tracking for spacecraft with two reaction wheels

ABSTRACTThis paper addresses the guidance and tracking problem for a rigid-spacecraft using two reaction wheels (RWs). The guidance problem is formulated as an optimal control problem on the special orthogonal group SO(3). The optimal motion is solved analytically as a function of time and is used to reduce the original guidance problem to one of computing the minimum of a nonlinear function. A tracking control using two RWs is developed that extends previous singular quaternion stabilisation controls to tracking controls on the rotation group. The controller is proved to locally asymptotically track the generated reference motions using Lyapunov's direct method. Simulations of a 3U CubeSat demonstrate that this tracking control is robust to initial rotation errors and angular velocity errors in the controlled axis. For initial angular velocity errors in the uncontrolled axis and under significant disturbances the control fails to track. However, the singular tracking control is combined with a nano-magnetic torquer which simply damps the angular velocity in the uncontrolled axis and is shown to provide a practical control method for tracking in the presence of disturbances and initial condition errors.

One hundred years of employee turnover theory and research.

We review seminal publications on employee turnover during the 100-year existence of the Journal of Applied Psychology. Along with classic articles from this journal, we expand our review to include other publications that yielded key theoretical and methodological contributions to the turnover literature. We first describe how the earliest papers examined practical methods for turnover reduction or control and then explain how theory development and testing began in the mid-20th century and dominated the academic literature until the turn of the century. We then track 21st century interest in the psychology of staying (rather than leaving) and attitudinal trajectories in predicting turnover. Finally, we discuss the rising scholarship on collective turnover given the centrality of human capital flight to practitioners and to the field of human resource management strategy. (PsycINFO Database Record

Bioremediation of copper-contaminated soils by bacteria

Although copper (Cu) is an essential micronutrient for all living organisms, it can be toxic at low concentrations. Its beneficial effects are therefore only observed for a narrow range of concentrations. Anthropogenic activities such as fungicide spraying and mining have resulted in the Cu contamination of environmental compartments (soil, water and sediment) at levels sometimes exceeding the toxicity threshold. This review focuses on the bioremediation of copper-contaminated soils. The mechanisms by which microorganisms, and in particular bacteria, can mobilize or immobilize Cu in soils are described and the corresponding bioremediation strategies-of varying levels of maturity-are addressed: (i) bioleaching as a process for the ex situ recovery of Cu from Cu-bearing solids, (ii) bioimmobilization to limit the in situ leaching of Cu into groundwater and (iii) bioaugmentation-assisted phytoextraction as an innovative process for in situ enhancement of Cu removal from soil. For each application, the specific conditions required to achieve the desired effect and the practical methods for control of the microbial processes were specified.

Development of a simple power controller for horizontal-axis standalone tidal current energy generation system

Tidal current energy, which is one of the most predictable forms of ocean renewable energy, is mainly utilised for electricity generation. This paper presents a simple control strategy for an optimal extraction of output power from a horizontal-axis variable speed tidal current turbine generation system with a permanent magnet synchronous generator (PMSG) that is driven directly by a fixed-pitch turbine. The maximum power point tracker (MPPT) extracts the turbine's maximum power from cut-in current velocity to rated value by measuring only dc link parameters. Together with a dc-dc converter PWM controller, MPPT variable-step searching algorithm is modelled and simulated using Matlab/Simulink software. The simulation results indicate that the variable-step searching algorithm can effectively track the maximum power point without collecting the data of tidal current velocity or rotor speed. Such MPPT controller provides a simple and practical method for the maximum power control of standalone tidal current energy conversion system.

Global Exponential Synchronization of Nonlinearly Coupled Complex Dynamical Networks with Time-Varying Coupling Delays

This paper focuses on the global exponential synchronization problem of nonlinearly coupled complex dynamical networks with time-varying coupling delays. Several simple and generic global exponential synchronization criteria are derived based on the Lyapunov stability theory and the Dini derivatives using the Halanay and generalized Halanay inequalities. These criteria rely on system parameters alone and can be used conveniently in practical applications. In addition, the system parameters do not satisfy the conditions of the proposed criteria. That is, the system itself cannot synchronize. However, system synchronization can be achieved by adding the appropriate feedback controllers, thereby providing a practical and effective control method for complex dynamical networks. An estimation method of exponential convergence rate is also presented. Finally, the effectiveness of the proposed criteria is verified through numerical simulations.