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Exploring Variability in Sea Level at a Tide Gauge Station through Control Charts
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作者 H.Bâkiİz 《Journal of Environmental & Earth Sciences》 CAS 2024年第1期11-18,共8页
Monitoring temporal changes in sea level is important in assessing coastal risk.Sea level anomalies at a tide gauge station,if kinematically conceived,include systematic variations such as trend,acceleration,periodic ... Monitoring temporal changes in sea level is important in assessing coastal risk.Sea level anomalies at a tide gauge station,if kinematically conceived,include systematic variations such as trend,acceleration,periodic oscillations,and random disturbances.Among them,the non-stationary nature of the random sea level variations of known or unknown origin at coastal regions has been long recognized by the sea level community.This study proposes the analyses of subgroups of random residual statistics of a rigorously formulated kinematic model solution of tide gauge variations using X-bar and S control charts.The approach is demonstrated using Key West,Florida tide gauge records.The mean and standard errors of 5-year-long subgroups of the residuals revealed that sea level changes at this location have been progressively intensifying from 1913 to the present.Increasing oscillations in sea level at this locality may be attributed partly to the thermal expansion of seawater with increasing temperatures causing larger buoyancy-related sea level fluctuations as well as the intensification of atmospheric events including wind patterns and the impact of changes in inverted barometer effects that will alter coastal risk assessments for the future. 展开更多
关键词 Climate change Sea level variance X-bar S control charts
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The Impact of Optimizing Details in the Operating Room on the Level of Knowledge, Attitude, and Practice of Hospital Infection Prevention and Control by Surgeons, as Well as the Effectiveness of Infection Control
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作者 Yuanyuan Zhang 《Surgical Science》 2024年第7期421-429,共9页
Objective: This paper aims to explore the impact of optimizing details in the operating room on the level of knowledge, attitude, and practice of hospital infection prevention and control by surgeons, as well as the e... Objective: This paper aims to explore the impact of optimizing details in the operating room on the level of knowledge, attitude, and practice of hospital infection prevention and control by surgeons, as well as the effectiveness of infection control. Methods: From January 2022 to June 2023, a total of 120 patients were screened and randomly divided into a control group (routine care and hospital infection management) and a study group (optimizing details in the operating room). Results: Significant differences were found between the two groups in the data of surgeons’ level of knowledge, attitude, and practice in hospital infection prevention and control, infection rates, and nursing satisfaction, with the study group showing better results (P Conclusion: The use of optimizing details in the operating room among surgeons can effectively improve surgeons’ level of knowledge, attitude, and practice in hospital infection prevention and control, reduce infection occurrence, and is worth promoting. 展开更多
关键词 Optimizing Details in the Operating Room Infection level of Knowledge ATTITUDE and Practice Infection control
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Fuzzy Sliding Mode Control for the Vehicle Height and Leveling Adjustment System of an Electronic Air Suspension 被引量:8
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作者 Xiao-Qiang Sun Ying-Feng Cai +2 位作者 Chao-Chun Yuan Shao-Hua Wang Long Chen 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2018年第2期238-250,共13页
The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper propo... The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper proposes a new adaptive controller to control the vehicle height and to adjust the roll and pitch angles of the vehicle body(leveling control) during the vehicle height adjustment procedures by an EAS system. A nonlinear mechanism model of the full?car vehicle height adjustment system is established to reflect the system dynamic behaviors and to derive the system optimal control law. To deal with the nonlinear characters in the vehicle height and leveling adjustment processes, the nonlinear system model is globally linearized through the state feedback method. On this basis, a fuzzy sliding mode controller(FSMC) is designed to improve the control accuracy of the vehicle height adjustment and to reduce the peak values of the roll and pitch angles of the vehicle body. To verify the effectiveness of the proposed control method more accurately, the full?car EAS system model programmed using AMESim is also given. Then, the co?simulation study of the FSMC performance can be conducted. Finally, actual vehicle tests are performed with a city bus, and the test results illustrate that the vehicle height adjustment performance is effectively guaranteed by the FSMC, and the peak values of the roll and pitch angles of the vehicle body during the vehicle height adjustment procedures are also reduced significantly. This research proposes an effective control methodology for the vehicle height and leveling adjustment system of an EAS, which provides a favorable control performance for the system. 展开更多
关键词 Electronic air suspension Height adjustment leveling control Fuzzy sliding mode control Vehicle tests
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Controlled Freezing and Open-Pulled Straw (OPS) Vitrification of In vitro Produced Bovine Blastocysts FollowingAnalysis of ATP Content and Reactive Oxygen Species (ROS) Level 被引量:3
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作者 ZHAO Xue-ming DU Wei-hua +4 位作者 WANG Dong HAO Hai-sheng QIN Tong LIU Yan ZHU Hua-bin 《Journal of Integrative Agriculture》 SCIE CSCD 2012年第3期446-455,共10页
To our knowledge,no single study has systemically compared cryopreservation efficiencies of bovine blastocysts derived from in vitro fertilization (IVF),intracytoplasmic sperm injection (ICSI) and somatic cell nuc... To our knowledge,no single study has systemically compared cryopreservation efficiencies of bovine blastocysts derived from in vitro fertilization (IVF),intracytoplasmic sperm injection (ICSI) and somatic cell nuclear transfer (SCNT) by controlled freezing and vitrification.This experiment,therefore,was designed to compare the cryopreservation of these blastocysts with controlled freezing and OPS vitrification.Adenosine-5’-triphosphate (ATP) content and reactive oxygen species (ROS) level in blastocysts were also analyzed.Firstly,for each type of blastocyst (IVF,ICSI or SCNT),significant differences were observed between the survival rates of the controlled freezing ((81.56±2.33),(68.18±4.72) or (47.89±5.83)%) and OPS vitrification groups ((92.24±4.54),(82.40±3.76) or (78.71±5.91)%;P〈0.05).Secondly,for each type of blastocyst (IVF,ICSI or SCNT),ATP content was significantly decreased after controlled freezing or vitrification,and the ATP content in the controlled freezing group (0.43±0.06),(0.35±0.05) or (0.21±0.02) pmol) was significantly lower than that found in the OPS vitrification group (0.62±0.04),(0.46±0.03) or (0.30±0.01) pmol;P〈0.05).Thirdly,ROS level in fresh IVF ((47.33±3.56) c.p.s (counted photons per second),ICSI ((36.51±2.58) c.p.s) or SCNT blastocysts ((26.44±1.49) c.p.s) was significantly lower than that found in the OPS vitrification group ((72.14±4.31),(58.89±3.89) or (40.11±5.73) c.p.s;P〈0.05),but higher than that of the controlled freezing group (34.41±3.32),(23.13±1.26) or (15.46±2.45) c.p.s;P〈0.05).The present study indicated that vitrification is more efficient in the cryopreservation of bovine blastocysts derived from IVF,ICSI or SCNT than controlled freezing.Furthermore,both vitrification and controlled freezing significantly altered the ATP content and ROS level in those blastocysts. 展开更多
关键词 ATP content controlled freezing in vitro production blastocysts OPS vitrification ROS level
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Application of Fuzzy Logic Controller to Level Control of Twin-Roll Strip Casting 被引量:2
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作者 QI Chun-yu DI Hong-shuang +1 位作者 ZHANG Xiao-ming GAO De-fu 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2003年第4期28-32,共5页
An intelligent fuzzy-PID controller consisting of fuzzy logic controller and PID controller was developed to control the molten steel level of twin-roll strip caster.Additionally,a feedforward differential PID control... An intelligent fuzzy-PID controller consisting of fuzzy logic controller and PID controller was developed to control the molten steel level of twin-roll strip caster.Additionally,a feedforward differential PID controller was used for stopper position control in order to avoid differential kick.It is proved by simulation that the proposed intelligent controller is able to obtain zero steady state error asymptotically and the control system is robust due to its fuggy behavior of the controller. 展开更多
关键词 twin-roll strip casting MODELING molten steel level control intelligent fuzzy-PID control
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Study of Interval Type-2 Fuzzy Controller for the Twin-tank Water Level System 被引量:4
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作者 赵涛岩 李平 曹江涛 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第6期1102-1106,共5页
For dealing with large static error due to poor immunity of the traditional fuzzy control, a novel interval type-2 fuzzy control system is proposed. By extending the typical membership functions to interval type-2 mem... For dealing with large static error due to poor immunity of the traditional fuzzy control, a novel interval type-2 fuzzy control system is proposed. By extending the typical membership functions to interval type-2 membership functions, the proposed control system can efficiently reduce the uncertain disturbance from real environment without increasing the design complexity. The simulation results on the water tank level control system showed that the proposed method succeeded in better static and dynamic control with stronger robust performance than the traditional fuzzy control method. 展开更多
关键词 interval type-2 fuzzy set fuzzy control system twin-tank water level system
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Two-echelon inventory model with service level constraint and controllable lead time sensitive to order quantity 被引量:3
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作者 李果 关旭 +1 位作者 刘梦麒 单汩源 《Journal of Central South University》 SCIE EI CAS 2013年第11期3324-3333,共10页
The decision-making and optimization of two-echelon inventory coordination were analyzed with service level constraint and controllable lead time sensitive to order quantity.First,the basic model of this problem was e... The decision-making and optimization of two-echelon inventory coordination were analyzed with service level constraint and controllable lead time sensitive to order quantity.First,the basic model of this problem was established and based on relevant analysis,the original model could be transformed by minimax method.Then,the optimal order quantity and production quantity influenced by service level constraint were analyzed and the boundary of optimal order quantity and production quantity was given.According to this boundary,the effective method and tactics were put forward to solve the transformed model.In case analysis,the optimal expected total cost of two-echelon inventory can be obtained and it was analyzed how service level constraint and safety factor influence the optimal expected total cost of two-echelon inventory.The results show that the optimal expected total cost of two-echelon inventory is constrained by the higher constraint between service level constraint and safety factor. 展开更多
关键词 service level constraint safety factor controllable lead time sensitivity to order quantity two-echelon
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Subjective annoyance caused by indoor low-level and low frequency noise and control method 被引量:2
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作者 DIGuo-qing ZHANGBang-jun SHANGQi 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2005年第1期135-140,共6页
The influence of low_level noise has not been widely noticed. This paper discovered that low_level and low frequency noise(A_weighted equivalent level L eq <45 dB) causes higher probability of subjective annoyance.... The influence of low_level noise has not been widely noticed. This paper discovered that low_level and low frequency noise(A_weighted equivalent level L eq <45 dB) causes higher probability of subjective annoyance. The fuzzy mathematic principle was applied to deal with the threshold level of subjective annoyance from noise in this study; there is preferable relationship between the indoor noise and noise annoyance at low frequency noise level. Study indicated at the same centered noise level, the change of annoyance probability is mainly caused by the change of the frequency spectrum characteristic of the indoor noise. Under low noise level environment, without change of the medium_low frequency noise, the slight increase of medium_high frequency noise level with the help of noise sheltering effect can significantly reduce the noise annoyance. This discovery brings a new resolution on how to improve the environmental quality of working or living places. A noise control model is given in this study according to the acoustic analysis. 展开更多
关键词 low-level noise subjective annoyance threshold level structural noise indoor noise noise control
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Quantitative feedback theory and zero phase error tracking control combined robust control for radar truck leveling simulator 被引量:1
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作者 凌轩 李晓辉 +1 位作者 朱玉泉 冯天麟 《Journal of Shanghai University(English Edition)》 2009年第5期384-390,共7页
Radar leveling system is the key equipment for improving the radar mobility and survival capability. A combined quantitative feedback theory (QFT) controller is designed for the radar truck leveling simulator in this ... Radar leveling system is the key equipment for improving the radar mobility and survival capability. A combined quantitative feedback theory (QFT) controller is designed for the radar truck leveling simulator in this paper, which suffers from strong nonlinearities and system parameter uncertainties. QFT can reduce the plant uncertainties and stabilize the system, but it fails to obtain high-precision tracking. This drawback can be solved by a robust QFT control scheme based on zero phase error tracking control (ZPETC) compensation. The combined controller not only possesses high robustness, but greatly improves the system performance. To verify the effiectiveness and the potential of the proposed controller, a series of experiments have been carried out. Experimental results have demonstrated its robustness against a large range of parameters variation and high tracking precision performance, as well as its capability of restraining the load coupling among channels. The combined QFT controller can drive the radar truck leveling platform accurately, quickly and stably. 展开更多
关键词 radar truck leveling simulator quantitative feedback theory (QFT) parameter uncertainties zero phase error tracking control (ZPETC) high robustness
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The Main Biological Hazards in Animal Biosafety Level 2 Facilities and Strategies for Control 被引量:4
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作者 LI Xiao Yan XUE Kang Ning +1 位作者 JIANG Jin Sheng LU Xuan Cheng 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2016年第4期300-304,共5页
Concern about the biological hazards involved in microbiological research, especially research involving laboratory animals, has increased in recent years. Working in an animal biosafety level 2 facility (ABSL-2), c... Concern about the biological hazards involved in microbiological research, especially research involving laboratory animals, has increased in recent years. Working in an animal biosafety level 2 facility (ABSL-2), commonly used for research on infectious diseases, poses various biological hazards. Here, the regulations and standards related to laboratory biosafety in China are introduced, the potential biological hazards present in ABSL-2 facilities are analyzed, and a series of strategies to control the hazards are presented. 展开更多
关键词 The Main Biological Hazards in Animal Biosafety level 2 Facilities and Strategies for control
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Simulating a fuzzy level controller for flotation columns 被引量:1
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作者 Liao Yinfei Liu Jiongtian Wang Yongtian Cao Yijun 《Mining Science and Technology》 EI CAS 2011年第6期815-818,共4页
Level control in flotation columns is an important factor that influences the recovery and the grade of concentrate from the column. A flotation column is a nonlinear, multi-variable problem with changeable parameters... Level control in flotation columns is an important factor that influences the recovery and the grade of concentrate from the column. A flotation column is a nonlinear, multi-variable problem with changeable parameters that traditional methods have difficulty controlling. We have applied fuzzy control methods to the flotation column and tested the performance of the design by Matlab/Simulink simulation. The simulations show that level control in the flotation column becomes smoother and more rapid with the fuzzy controller. Compared to PID control methods the overshoot in valve position, the adjustment time, and the robustness of the controller are all improved. This indicates that it is suitable to model fuzzy controllers in applications for the study of automatic control of flotation column. 展开更多
关键词 Flotation column Fuzzy control level Simulation
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Measurement and AFPS control of molten steel level in strip casting
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作者 LiyeZhu TihuaWu YuanFang 《Journal of University of Science and Technology Beijing》 CSCD 2005年第1期16-22,共7页
The measurement and control of the molten steel level are studied, which affect the quality of strip surface in strip casting. A system of molten steel measurement with a CCD (Charge Coupled Devices) sensor is designe... The measurement and control of the molten steel level are studied, which affect the quality of strip surface in strip casting. A system of molten steel measurement with a CCD (Charge Coupled Devices) sensor is designed, real-time measured data are given and its precision is analyzed. The level fluctuation model is derived, and an adaptive fuzzy-PID controller with supervisory control (AFPS) is proposed. The stability of the system is proved using Lyapunov theorem, and the simulation results are given when the model, the casting speed and the roll gap change. It is suggested that this kind of coupled nonlinear and time varying system is stable and robust using the designed AFPS controller. 展开更多
关键词 strip casting molten steel level CCD adaptive fuzzy-PID supervisory controller
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Non-Linear Tank Level Control for Industrial Applications
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作者 Michael Short A. Arockia Selvakumar 《Applied Mathematics》 2020年第9期876-889,共14页
Tank level control is ubiquitous in industry. The focus of this paper is on accurate liquid level control in single tank systems which can be actuated continuously and modulation of the level setpoint is also required... Tank level control is ubiquitous in industry. The focus of this paper is on accurate liquid level control in single tank systems which can be actuated continuously and modulation of the level setpoint is also required, for example in cascade control loops or supervisory Model Predictive Control (MPC) applications. To avoid common problems encountered when using fixed gain or adaptive/gain scheduled schemes, an accurate technique based around feedback linearization and Proportional Integral (PI) control is introduced. This simple controller can maintain linear performance over the full operating range of a uniform tank. As will be demonstrated, the implementation overhead compared to a regular PI controller is negligible, making it ideal for industrial implementation. Implementation details and parameter identification for adaptive implementation are discussed. Simulations coupled with experimental results using a large-scale laboratory level control system using commercial industrial control equipment validate the approach, and illustrate its effectiveness for both level tracking and disturbance rejection. 展开更多
关键词 level control Non-Linear control Feedback Linearization
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A Novel Fuzzy Direct Torque Control System for Three-level Inverter-fed Induction Machine 被引量:2
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作者 Shu-Xi Liu Ming-Yu Wang +1 位作者 Yu-Guang Chert Shan Li 《International Journal of Automation and computing》 EI 2010年第1期78-85,共8页
Diode clamped multi-level inverter (DCMLI) has a wide application prospect in high-voltage and adjustable speed drive systems due to its low stress on switching devices, low harmonic output, and simple structure. Ho... Diode clamped multi-level inverter (DCMLI) has a wide application prospect in high-voltage and adjustable speed drive systems due to its low stress on switching devices, low harmonic output, and simple structure. However, the problem of complexity of selecting vectors and capacitor voltage unbalance needs to be solved when the algorithm of direct torque control (DTC) is implemented on DCMLI. In this paper, a fuzzy DTC system of an induction machine fed by a three-level neutral-point-clamped (NPC) inverter is proposed. After introducing fuzzy logic, optimal selecting switching state is realized by applying various strategies which can distinguish the grade of the errors of stator flux linkage, torque, the neutral-point potential, and the position of stator flux linkage. Consequently, the neutral-point potential unbalance, the dr/dr of output voltage and the switching loss are restrained effectively, and desirable dynamic and steady-state performances of induction machines can be obtained for the DTC scheme. A design method of the fuzzy controller is introduced in detail, and the relevant simulation and experimental results have verified the feasibility of the proposed control algorithm. 展开更多
关键词 Multi-level inverter direct torque control (DTC) fuzzy controller space voltage vector induction machine
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Is nonlinear model predictive control with fuzzy predictive model proper for managing the blood glucose level in typeI diabetes?
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作者 Maryam Ahmadi Amir Homayoon Jafari 《Journal of Biomedical Science and Engineering》 2012年第2期63-74,共12页
In recent decades, due to the increasing risk of diabetes, the measurement and control of the blood sugar is of great importance. In typeI diabetes, because of the lack of insulin secretion, the cells cannot absorb gl... In recent decades, due to the increasing risk of diabetes, the measurement and control of the blood sugar is of great importance. In typeI diabetes, because of the lack of insulin secretion, the cells cannot absorb glucose, and thus have a low level of glucose. To control blood glucose, the insulin must be injected to the body. In fact, the injection must be in a completely controlled environment. If the level of the insulin exceeds the physiological limits, it may cause death. This paper presents an online approach to control the blood glucose level using a nonlinear model predictive control. This method, maintains the level of blood glucose concentration within a normal range. Thus, the blood glucose level is measured in each minute and predicted for the next time interval. If that is not in the normal range, amount of the insulin which must be injected will be determined. The proposed control approach includes important features such as model uncertainties and prevents acute decrease in the blood glucose level, and instability. In order to assess performance of the proposed controller, computer simulations have been carried out in Matlab/Simulink. Simulation results will reveal the effectiveness of the proposed nonlinear model predictive controller in adjusting the blood glucose level by injecting required insulin. So if the nutrition of the person decreases instantly, the hypoglycemia does not happen. 展开更多
关键词 DIABETES Delay of Insulin-Glucose REGULATORY System Blood GLUCOSE level Nonlinear Model Predictive control
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Evaluation of Environmental Sound Pressure Level,Drawing of Noise-Isosonic Map Using Surfer V.19,and Prioritization of Engineering Noise Control Methods Using the Analytic Hierarchy Process(AHP):A Field Study in CGS Stations
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作者 Sajad Zare Abdolrasoul Rahmani +3 位作者 Javad Korouzhdeh Masoud Hajghani Rouhollah Rostami Reza Esmaeili 《Sound & Vibration》 EI 2022年第3期275-291,共17页
Noise pollution is one of the most significant harmful physical factors in the industrial and occupational environments.Due to the high costs of exposure to excessive noise;continuous sound evaluation,propose and impl... Noise pollution is one of the most significant harmful physical factors in the industrial and occupational environments.Due to the high costs of exposure to excessive noise;continuous sound evaluation,propose and implement noise control plans in occupational environments is necessary.Thus,the present study aimed to review environmental sound measurements,drawing of noise maps,and prioritizing the engineering noise control methods using the Analytic Hierarchy Process(AHP).This study was a descriptive-analytical study that aimed to assess occupational noises and present a control plan in the City Gas Stations(CGSs)of Kerman,Iran in 2021.The present study was done in two phases.In the first phase,six CGSs were investigated to measure and evaluate the noise.In addition,the noise map of a CGS was drawn using the Surfer software.Finally,the AHP was used in the second phase of the research to prioritize the control measures.In this phase,four criteria and ten alternatives were identified.According to first phase results,the sound pressure level(SPL)of the stations varied from 76 to 98 dBA.Besides,the majority of the studied stations had a sound level higher than 85 dBA(danger zone).The second phase of the study showed that out of the four evaluated criteria,the executability criterion had the highest impact and the cost criterion had the lowest impact on the selection of control measures with a weight of 0.587 and 0.052,respectively.Based on the results of prioritization of the alternatives,using a silenced regulator(weight of 0.223)and increasing the thickness of the tube(weight of 0.023)had the highest and lowest priorities among the alternatives,respectively.The use of engineering noise control methods such as using silenced regulators was the best way to control the noises of CGSs.Additionally;it is noteworthy that AHP is a practical method for prioritizing alternatives to achieve the most accurate decision-making.The results of AHP can be of great help to health and safety experts and managers in choosing the sound engineering control measures more precisely. 展开更多
关键词 Engineering noise control sound pressure level noise map analytic hierarchy process
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Strategy for Controlling the Level in a Dissolved Air Flotation Chamber
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作者 Rodrigo Almeida Galdino Alex Elton de Moura +1 位作者 Valdemir Alexandre dos Santos Leonie Asfora Sarubbo 《Journal of Chemistry and Chemical Engineering》 2015年第5期344-352,共9页
The aim of the present study was to implant an efficient strategy for controlling the level of the effluent-oily foam interface in a DAF (dissolved air flotation) chamber of a pilot-scale prototype. DAF has been suc... The aim of the present study was to implant an efficient strategy for controlling the level of the effluent-oily foam interface in a DAF (dissolved air flotation) chamber of a pilot-scale prototype. DAF has been successfully used in the treatment of oily water, which is one of the main environmental problems in different industrial facilities. Along with important operational parameters, such as microbubble size and flow rate, the control strategy for the automation of a DAF chamber may be an important tool for increasing efficiency. Controlling the level was the strategy chosen to enhance the separation efficiency in a pilot-scale DAF prototype, with monitoring performed using a computational program in LabVIEW (laboratory virtual instrument engineering workbench). The findings demonstrate that it is possible to maintain the level of the fluid at a reference value established by the operator using the software program through the application of classic proportional integral derivative controllers. Using this control tool, the efficiency of water-oil separation in the pilot flotation chamber prototype was increased to nearly 98%. 展开更多
关键词 Dissolved air flotation level control LABVIEW proportional integral derivative liquid-liquid separation.
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A Space Vector Modulation Based Three-level PWM Rectifier under Simple Sliding Mode Control Strategy 被引量:1
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作者 Azeddine Draou Senior Mieee 《Energy and Power Engineering》 2013年第3期28-35,共8页
In this paper, a voltage oriented control strategy for three-level PWM rectifier based on Sliding Mode Control (SMC) is introduced in order to obtain fast and accurate response of dc-bus voltage. To verify the validit... In this paper, a voltage oriented control strategy for three-level PWM rectifier based on Sliding Mode Control (SMC) is introduced in order to obtain fast and accurate response of dc-bus voltage. To verify the validity of the analysis and the feasibility of the proposed control method a set of simulation tests have been conducted using Matlab/Simulink. The simulation results show that compared to the conventional PI controller, the SMC can reduce drastically the three-level rectifier’s voltage fluctuation and improve the dynamic response of dc-bus significantly. 展开更多
关键词 THREE-level PWM RECTIFIER VOLTAGE Oriented control SLIDING Mode control Unbalanced Input VOLTAGE
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Serum Levels of Antioxidant Vitamins in Relation to Coronary Artery Disease: A Case Control Study of Koreans
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作者 KIM S. Y. LEE-KIM Y. C. +7 位作者 KIM M. K. SUH J. Y. CHUNG E. J. CHO. S. Y. CHO. B. K. AND SUHI(Department of Food and Nutrition Cardiovascular Center Department of Preventive Medicine Yonsei University, Seoul, Korea) 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 1996年第2期229-235,共7页
With the changes in trends of disease pattern from infectious to chronic degenerative disease, cardiovascular disease has been considered as the major cause of death in Korea.Numerous studies have been done on the ant... With the changes in trends of disease pattern from infectious to chronic degenerative disease, cardiovascular disease has been considered as the major cause of death in Korea.Numerous studies have been done on the antioxidant effects of some vitamins in the prevention of chronic illness, but not many in relation to the cardiovascular disease.Therefore, the relation between antioxidant vitamins, mainly α-tocopherol (α-T) and B-carotene (B-C), and coronary artery disease (CAD) such as angina pectoris and myocardial infarction has been investigated in this study.The blood samples were obtained from the CAD patients who were angiographically diagnosed within a month (100 case group). Patients who had an experience of PTCA or CABG were excluded from the study. Control subjects were healthy adults who had normal EKG values, no chest pain and no past history of cardiac disease (100 control group). All subjects were free of serum lipid lowering drugs. Serum α-T and B-C were analysed using HPLC. In addition to antioxidant vitamins, serum lipids (total cholesterol, HDL, TG) were also measured. Each case and control was matched in terms of age and sex. And all the CAD risk factors such as blood pressure, smoking, alcohol, serum lipid profile and BMI were adjusted to determine pure effect(s) of α-T and B-C on the CAD.The concentrations of both α-T and B-C were significantly lower in the CAD group than those in control group (P<0.05); in CAD group, mean values of α-T and B-C were 11.9±7.2 (μg/ml), 35.8±3.1 (μg/dl) respectively. As for the levels of B-C, it shows inverse relation with age, but not for the α-T Ievels. Serum levels of both vitamins did not show any significant differences in terms of sex, but men have a tendency o higher levels of B-C,but lower levels of α-T 展开更多
关键词 CASE Serum levels of Antioxidant Vitamins in Relation to Coronary Artery Disease A Case control Study of Koreans GSH
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EWMA control chart based on its first hitting time and coronavirus alert levels for monitoring symmetric COVID-19 cases
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作者 Areepong Yupaporn Sunthornwat Rapin 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2021年第8期364-374,共11页
Objective:To define the alert levels for the total number of COVID-19 cases derived by using quantile functions to monitor COVID-19 outbreaks via an exponentially weighted moving-average(EWMA)control chart based on th... Objective:To define the alert levels for the total number of COVID-19 cases derived by using quantile functions to monitor COVID-19 outbreaks via an exponentially weighted moving-average(EWMA)control chart based on the first hitting time of the total number of COVID-19 cases following a symmetric logistic growth curve.Methods:The cumulative distribution function of the time for the total number of COVID-19 cases was used to construct a quantile function for classifying COVID-19 alert levels.The EWMA control chart control limits for monitoring a COVID-19 outbreak were formulated by applying the delta method and the sample mean and variance method.Samples were selected from countries and region including Thailand,Singapore,Vietnam,and Hong Kong to generate the total number of COVID-19 cases from February 15,2020 to December 16,2020,all of which followed symmetric patterns.A comparison of the two methods was made by applying them to a EWMA control chart based on the first hitting time for monitoring the COVID-19 outbreak in the sampled countries and region.Results:The optimal first hitting times for the EWMA control chart for monitoring COVID-19 outbreaks in Thailand,Singapore,Vietnam,and Hong Kong were approximately 280,208,286,and 298 days,respectively.Conclusions:The findings show that the sample mean and variance method can detect the first hitting time better than the delta method.Moreover,the COVID-19 alert levels can be defined into four stages for monitoring COVID-19 situation,which help the authorities to enact policies that monitor,control,and protect the population from a COVID-19 outbreak. 展开更多
关键词 COVID-19 alert levels Symmetric pattern of the total number of COVID-19 cases Monitoring COVID-19 situation EWMA control chart
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