On the extraction technique of the single-coil self-feedback signal on a standard vibration table

2017 ◽  
Vol 24 (18) ◽  
pp. 4316-4324 ◽  
Author(s):  
Qinglei Chi ◽  
Shuaikun Shang
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Low Cost ◽  
Low Frequency ◽  
Signal Extraction ◽  
Feedback Signal ◽  
Extraction Technology ◽  
Speed Sensor ◽  
Motion Signal ◽  
Low Frequency Motion

In the process of calibration on vibration and shock transducers, it is necessary for the vibration table to generate a small sine-function form distortion as the excitation signal, and the closed-loop servo feedback technology is one of the proven effective ways to reduce low-frequency motion signal distortion of the vibration table. In this paper, we report a method based on the principle of closed-loop servo feedback that can directly extract induction electromotive force of the vibrator coil. This method solves the problems caused by using sensors in the process of getting the vibration signals. Furthermore, this device has some advantages such as small size, light weight, low cost and simple maintenance. In this article, the system components and technical indexes and analyzis of the control method of the vibration table are described. Next, we compare the wave distortion obtained using monocoil signal extraction technology and that obtained using relative speed sensor. Finally, the error analysis of monocoil signal extraction technology is carried out, and the experiment is finished to prove this analysis.

Simulation of Multi-Closed Loop Control With Feed Forward Control of Micro-Vibration Isolation Platform

2014 ◽  
Author(s):  
Qianqian Wu ◽  
Honghao Yue ◽  
Rongqiang Liu ◽  
Liang Ding ◽  
Zongquan Deng
Keyword(s):  
Vibration Isolation ◽  
Closed Loop ◽  
Control Method ◽  
Magnetic Levitation ◽  
Low Frequency ◽  
Closed Loop Control ◽  
Vibration Source ◽  
Feed Forward ◽  
Loop Control ◽  
Micro Vibration

Micro vibration in the ideal-zero gravity environments has complicated science experiment results. A magnetic levitation vibration isolation platform is needed to isolate the vibration source to provide acceptable acceleration level in low frequency range. The configuration of the Lorentz actuators is discussed in the paper. And the modeling of the transformation matrix from the force to the current is deduced. In order to generate desired force, the current is needed to predict precisely. To study the characteristics of the system, the single degree of freedom system is analyzed. A multi-closed loop control scheme is put forward to achieve vibration isolation control. To evaluate the effect of each control parameter, frequency domain analysis of the transfer function is simulated. In order to further increase the control effectiveness, a feed forward compensation control algorithm is added to control the vibration of cables that connect the upper platform and the base. By regulating these control parameters, bode curves can be obtained. Comparing the two methods, it can be concluded that the control method with feed forward compensation is better than the one without that.

Peaks in the beta band of the human subthalamic nucleus: a case for low beta and high beta activity

2021 ◽  
pp. 1-9
Author(s):  
Annika Plate ◽  
Franz Hell ◽  
Jan H. Mehrkens ◽  
Thomas Koeglsperger ◽  
Ayse Bovet ◽  
...  
Keyword(s):  
Subthalamic Nucleus ◽  
Closed Loop ◽  
Low Frequency ◽  
Bimodal Distribution ◽  
Feedback Signal ◽  
Beta Activity ◽  
Beta Band ◽  
Different Types ◽  
Specific Frequency ◽  
The Impact

OBJECTIVE Peaks in the beta band of local field potentials (LFPs) may serve as a biological feedback signal for closed-loop deep brain stimulation (DBS) in Parkinson’s disease (PD). However, the specific frequency of such peaks and their response to DBS and to different types of movement remains uncertain. In the present study, the authors examined the abundance of discernible peaks in the beta band and the effect of different types of movement and DBS on these peaks. METHODS Subthalamic nucleus LFPs were analyzed from 38 patients with PD in a frequency range between 10 and 35 Hz, as well as the impact of movement (gait, hand movements) and electrical stimulation on these peaks. The position of the electrode segments from which LFPs were recorded was computed. RESULTS The authors found a bimodal distribution of peaks in the beta band with discernible high- (27 Hz) and low-frequency (15 Hz) peaks. Movement of either hand had no significant effect on these peaks, whereas walking significantly reduced high-frequency beta peaks but not the peaks in the low beta band. Stimulation caused an amplitude-dependent suppression of both peaks. CONCLUSIONS DBS suppresses LFP beta peaks of different frequencies, whereas beta suppression caused by movement is dependent on the type of movement and frequency of the peak. These results will support the investigation of distinct LFP spectra for the application of closed-loop DBS.

Homogenate Extraction of Dihydroartemisinin from Artemisia Hedinii and Its Antifungal Activity

2021 ◽  
Author(s):  
Cong You ◽  
Jun Yu ◽  
Guangjiong Qin ◽  
JinPeng Yang ◽  
Chunlei Yang ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Crude Extract ◽  
Spore Germination ◽  
Alternaria Alternata ◽  
Low Cost ◽  
Pathogenic Fungi ◽  
Extraction Yield ◽  
Optimal Conditions ◽  
Extraction Technology ◽  
Homogenate Extraction

Abstract Background Artemisia hedinii is a well-known traditional Chinese medicine. It can be used to extract dihydroartemisinin (DHA). Objective The purpose of this study was to explore the optimal conditions for the homogenate extraction of DHA from A. hedinii and the antifungal activity of DHA. Methods In this study, single factor experiments and response surface method were used to determine the optimal extraction conditions of crude extract and DHA, the method of spore germination was used to study the antifungal activity of DHA to Alternaria alternata. Result The optimal conditions were found as fellow: ratio of liquid to material 22 mL/g; Extraction time 60 s; soaking time 34 min. Under these conditions, extraction yield of DHA was (1.76 ± 0.04%). When the concentration of crude extract were 0.5 and 8 mg/mL, the spore germination inhibition rates of Alternaria alternata were (17.00 ± 2.05%) and (92.56 ± 2.01%), which were 3.34 and 1.15 times that of DHA standard, respectively. Conclusion Homogenate extraction technology is a fast and efficient method to extract DHA from A. hedinii. The crude extract has significant antifungal activity against A. alternata with low cost, which provides a possibility for the use of DHA in the prevention and treatment of plant pathogenic fungi. Highlights The optimum conditions of the extraction of DHA from A. hedinii by homogenate extraction were obtained. DHA has antifungal activity against A. alternata. Compared with pure DHA, the crude extract has stronger antifungal activity against A. alternata.

scholarly journals Patients in intensive care unit for COVID-19 pneumonia: the lung ultrasound patterns at admission and discharge. An observational pilot study

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Persona Paolo ◽  
Valeri Ilaria ◽  
Zarantonello Francesco ◽  
Forin Edoardo ◽  
Sella Nicolò ◽  
...  
Keyword(s):  
Intensive Care ◽  
Lung Ultrasound ◽  
Low Cost ◽  
Low Frequency ◽  
Specific Pattern ◽  
University Hospital ◽  
Left Hemithorax ◽  
Significant Difference ◽  
The Right ◽  
B Lines

Abstract Background During COVID-19 pandemic, optimization of the diagnostic resources is essential. Lung Ultrasound (LUS) is a rapid, easy-to-perform, low cost tool which allows bedside investigation of patients with COVID-19 pneumonia. We aimed to investigate the typical ultrasound patterns of COVID-19 pneumonia and their evolution at different stages of the disease. Methods We performed LUS in twenty-eight consecutive COVID-19 patients at both admission to and discharge from one of the Padua University Hospital Intensive Care Units (ICU). LUS was performed using a low frequency probe on six different areas per each hemithorax. A specific pattern for each area was assigned, depending on the prevalence of A-lines (A), non-coalescent B-lines (B1), coalescent B-lines (B2), consolidations (C). A LUS score (LUSS) was calculated after assigning to each area a defined pattern. Results Out of 28 patients, 18 survived, were stabilized and then referred to other units. The prevalence of C pattern was 58.9% on admission and 61.3% at discharge. Type B2 (19.3%) and B1 (6.5%) patterns were found in 25.8% of the videos recorded on admission and 27.1% (17.3% B2; 9.8% B1) on discharge. The A pattern was prevalent in the anterosuperior regions and was present in 15.2% of videos on admission and 11.6% at discharge. The median LUSS on admission was 27.5 [21–32.25], while on discharge was 31 [17.5–32.75] and 30.5 [27–32.75] in respectively survived and non-survived patients. On admission the median LUSS was equally distributed on the right hemithorax (13; 10.75–16) and the left hemithorax (15; 10.75–17). Conclusions LUS collected in COVID-19 patients with acute respiratory failure at ICU admission and discharge appears to be characterized by predominantly lateral and posterior non-translobar C pattern and B2 pattern. The calculated LUSS remained elevated at discharge without significant difference from admission in both groups of survived and non-survived patients.

Balanced heterodyne signal extraction in a postmodulated Sagnac interferometer at low frequency

1997 ◽  
Vol 22 (19) ◽  
pp. 1485 ◽  
Author(s):  
Ke-Xun Sun ◽  
Martin M. Fejer ◽  
Eric K. Gustafson ◽  
Robert L. Byer
Keyword(s):  
Low Frequency ◽  
Signal Extraction ◽  
Sagnac Interferometer ◽  
Heterodyne Signal

Space Station Environmental, Thermal Control and Life Support (ETCLS): “Meeting the Evolutionary Growth Challenge”

1984 ◽  
Vol 106 (4) ◽  
pp. 287-291
Author(s):  
H. F. Brose
Keyword(s):  
Closed Loop ◽  
Life Support ◽  
Technology Development ◽  
Low Cost ◽  
Space Station ◽  
Thermal Control ◽  
Development Effort ◽  
Program Cost ◽  
Preparedness Plan ◽  
Evolutionary Growth

Renewed interest and planning for a Space Station, probably NASA’s next major space activity, poses a new challenge for ETCLS technology not previously emphasized. Over the past two decades, regenerative life support technology development for Space Station has been underway. This development effort was always aimed at regenerative (closed loop) life support for a full capability Space Station. The level of priority for manned space presence and current budgetary pressures dictate the need for a low cost profile program with an evolutionary growth Space Station. The initial capability may be a small station with a crew of 2 or 3. This station could grow in size and capability by the addition of modules to a station with a crew of 8 to 12 with the possibility of multiple stations in orbit. Depending upon the selected missions, the early station may be best served by an open or only partially closed loop ETCLS whereas the final station may need a completely closed loop ETCLS. The challenge would be to grow in-orbit the ETCLS system capability in a “no-throw-away” fashion in order to minimize annual and total program cost. This paper discusses a possible ETCLS system evolutionary growth scenario, the Space Station architecture variations influencing the ETCLS system design, and a technology preparedness plan for Space Station ETCLS.

The Investigation of the Optimization Scheme of the Low-cycle Fatigue Cropping Based on the Acoustic Emission Technique

2021 ◽  
Author(s):  
Yujian Ren ◽  
Jingxiang Li ◽  
Yuanzhe Dong ◽  
Dong Jin ◽  
Shengdun Zhao
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
Control Method ◽  
Low Cycle Fatigue ◽  
Control Strategies ◽  
Low Frequency ◽  
Loading Frequency ◽  
Cycle Fatigue ◽  
Al 6061 ◽  
Whole Process

Abstract High efficiency and good section quality are two main objectives of metal bar cropping. A suitable control method can help to achieve both goals. An investigation of the control method of low-cycle fatigue cropping (LCFC) based on the acoustic emission (AE) technique has been proposed in this study. Ring-down counts and kurtosis are used to monitor the whole process of LCFC. The results showed that kurtosis is more suitable for monitoring the LCFC process and as a critical parameter to optimize the control method than ring-down counts in the noisy factory environment.Moreover, three types of materials are studied in this experiment; by combine with the AE results, macroscopic images and microscopic images of sections, characteristics of various LCFC stages are obtained. The results also indicated reduce the area of the transient fracture zone is the key to improve the section quality. Reducing the load frequency before the unstable crack propagation stage will beneficial to realize the goals. Based on the evaluation of kurtosis, an optimized control method is presented, and two control parameters: transient time T and the critical value of the slope of kurtosis C are determined. For 16Mn, 1045 and Al 6061, the T is 5s, 10s, and 1s, respectively. For 16Mn, 1045, and Al 6061, the C is 100, 300, and 0, respectively. Two parameters, h and S, are used to evaluate the section quality and four control strategies are compared. The results indicate the optimal control methods can improve the section quality effectively. The influence trend of reducing loading frequency is investigated by further comparison. It can be seen as the frequency decreases, the efficiency of the section quality improving decreases. In order to realize the optimal results, different control strategies are adopted for different materials. Strategy 1 (high frequency is 20Hz，high frequency thought the whole process), strategy 2 (high frequency is 20Hz，low frequency is 8.33Hz), and strategy 3 (high frequency is 20Hz，low frequency is 6.67Hz) is suitable for Al 6061, 1045, and 16Mn, respectively.

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