Vibration analysis and control of a screw compressor outlet piping system

2018 ◽  
Vol 233 (2) ◽  
pp. 403-411
Author(s):  
Ying Zhao ◽  
Jianmei Feng ◽  
Bin Zhao ◽  
Shuangmei Zhou ◽  
Zhou Tang ◽  
...  
Keyword(s):  
Vibration Analysis ◽  
Pressure Pulsation ◽  
Measurement Data ◽  
Screw Compressor ◽  
Piping System ◽  
Finite Element Models ◽  
Excessive Pressure ◽  
First Order ◽  
Vibration Problem ◽  
And Control

The severe vibration of a screw compressor outlet piping system caused the premature failures of some thermowells and the unplanned shut down of the compressor system. The root causes of the vibration problem were investigated by numerical simulations. An acoustic model was established to predict the pressure pulsation of the gas inside the pipelines, and two finite element models were built to study the vibration characteristics of the overall piping system and of the thermowells. The numerical results indicated that the vibration problem may be attributed to the excessive pressure nonuniformity of the gas inside the pipelines, low overall stiffness of the piping system and the first-order structural resonance occurred on the thermowells. A pulsation attenuator was added and the pipelines were rearranged to reduce the pressure pulsation, some pipe supports were added to improve the overall stiffness of the piping system, and the thermowells were reinforced to avoid the first-order structural resonance. After the modifications, the field measurement data showed that the vibration of the piping system decreased significantly, and the modified piping system has been operating normally for nearly two years.

Vibration Analysis and Control for Reciprocating Compressor Piping System

2012 ◽  
Vol 157-158 ◽  
pp. 930-934
Author(s):  
Yong Dong Li ◽  
Sheng Liang Han ◽  
Jie Liu ◽  
Ji Yong Liu ◽  
He Du
Keyword(s):  
Vibration Analysis ◽  
Operating Conditions ◽  
Design Parameters ◽  
Piping System ◽  
Reciprocating Compressor ◽  
Adequate Model ◽  
Column System ◽  
System Pressure ◽  
Compressor Pipe ◽  
And Control

Following the adequate model of the reciprocating compressor piping system and the compressor design parameters, operating conditions and gas parameters, the mechanical system of compressor piping, gas-column system, pressure pulsations and of vibration response are numerically simulated. And the main factor bringing to the compressor piping system vibration is identified. A reasonable way to controlling piping vibration is developed to achieve a better efficiency. Keywords: Compressor; Pipe vibration; Vibration Analysis; numerical simulation.

The effect of practicing yoga during pregnancy on labor stages length, anxiety and pain: a randomized controlled trial

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ellahe Mohyadin ◽  
Zohreh Ghorashi ◽  
Zahra Molamomanaei
Keyword(s):  
Controlled Trial ◽  
Intervention Group ◽  
Total Duration ◽  
Measurement Data ◽  
Labor Pain ◽  
Control Group ◽  
Chi Square ◽  
Nulliparous Women ◽  
Two Stages ◽  
And Control

AbstractBackgroundAnxiety and fear of labor pain has led to elevated cesarean section rate in some countries. This study was conducted to investigate the effect of yoga in pregnancy on anxiety, labor pain and length of labor stages.MethodsThis clinical trial study was performed on 84 nulliparous women who were at least 18 years old and were randomly divided into two groups of yoga and control groups. Pregnancy Yoga Program consisting of 6 60-min training sessions was started every 2 weeks from week 26 of pregnancy and continued until 37 weeks of gestation. Anxiety severity at maternal admission to labor was measured by the Spielbergers State-Trait Anxiety Inventory, and labor pain was measured by Visual Analogue Scale (VAS) at dilatation (4–5 cm) and 2 h after the first measurement. Data were analyzed using Chi-Square and t-test.ResultsIntervention group reported less pain at dilatation (4–5 cm) (p=0.001) and 2 h after the first measurement (p=0.001) than the control group. Stat anxiety was also lower in intervention group than the control group (p=0.003) at the entrance to labor room. Subjects in the control group required more induction compared to intervention group (p=0.003). Women in intervention group experienced shorter duration of the first phase of the labor than the control group (p=0.002). Also, the total duration of two stages of labor was shorter in intervention group than the control group (p=0.003).ConclusionsPracticing yoga during pregnancy may reduce women’s anxiety during labor; shorten labor stages, and lower labor pain.

A Design of Coal Mine Security Monitoring Substation Based on ZIGBEE and CAN Bus

2014 ◽  
Vol 971-973 ◽  
pp. 1033-1036
Author(s):  
Hui Jun Wang ◽  
Zhi Qun Yong
Keyword(s):  
Coal Mine ◽  
Can Bus ◽  
Measurement Data ◽  
Environmental Parameters ◽  
Monitoring And Control ◽  
Monitoring And Control System ◽  
Security Monitoring ◽  
Mine Development ◽  
Security Monitoring System ◽  
And Control

In view of the shortcoming such as wiring difficulties, poor scalability, and big cable usage in present mine security monitoring system, this paper puts forward a kind of substation monitoring and control system based on ZIGBEE and CAN. With the core of core, The system collects various measurement data of sensors through the ZIGBEE wireless network, realizes the to collect, and then through the CAN bus to realize the transmission of control commands and data of the up and down machine, and monitor the production parameters and environmental parameters in the coal mine. Experiments show that the monitoring substation is of high real-time performance, good stability, strong expansibility, etc., and can meet the requirements of the coal mine development and mining.

scholarly journals Manifold Calculus in System Theory and Control—Fundamentals and First-Order Systems

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2092
Author(s):  
Simone Fiori
Keyword(s):  
Control Systems ◽  
Linear Systems ◽  
Linear Control Systems ◽  
First Order ◽  
Curved Manifolds ◽  
Non Linear ◽  
Covariant Derivation ◽  
Non Linear Systems ◽  
And Control

The aim of the present tutorial paper is to recall notions from manifold calculus and to illustrate how these tools prove useful in describing system-theoretic properties. Special emphasis is put on embedded manifold calculus (which is coordinate-free and relies on the embedding of a manifold into a larger ambient space). In addition, we also consider the control of non-linear systems whose states belong to curved manifolds. As a case study, synchronization of non-linear systems by feedback control on smooth manifolds (including Lie groups) is surveyed. Special emphasis is also put on numerical methods to simulate non-linear control systems on curved manifolds. The present tutorial is meant to cover a portion of the mentioned topics, such as first-order systems, but it does not cover topics such as covariant derivation and second-order dynamical systems, which will be covered in a subsequent tutorial paper.

scholarly journals Vibration Analysis and Control of a Vibration Screed System for Asphalt Pavers

2020 ◽  
Vol 25 (3) ◽  
pp. 363-372
Author(s):  
Vanliem Nguyen ◽  
Zhenpeng Wu ◽  
Beiping Zhang ◽  
Zhang Jian Run
Keyword(s):  
Working Conditions ◽  
Vibration Analysis ◽  
Excitation Frequency ◽  
Mean Square ◽  
Dynamic Parameters ◽  
Objective Functions ◽  
Nonlinear Dynamic Model ◽  
Compression Efficiency ◽  
Centre Of Gravity ◽  
And Control

To reduce shaking of a vibration screed system (VSS) and improve the paving performance of an asphalt paver (AP), the root-mean-square (RMS) acceleration responses at points on the front and rear screed floors are analyzed via an experimental method. A 3D nonlinear dynamic model of the VSS is also built to evaluate the influence of the dynamic parameters of the VSS on the compression efficiency, paving quality, and working stability of the AP based on the objective functions of the vertical, pitching, and rolling RMS values at the centre of gravity of the screed. The angular deviations, $alpha$ and $gamma$, of the tamper are then controlled to improve the paving performance. The research results show that the excitation frequency, $f_{t}$, and both angular deviations, $alpha$ and $gamma$, of the tamper strongly affect the paving performance. The compression efficiency is quickly enhanced, while both paving quality and working stability are significantly reduced with increasing the excitation frequency $f_{t}$ and reducing the angular deviations. $alpha$ and $gamma$. and vice versa. Additionally, the screed shaking and paving performance of the AP are remarkably improved by control of the angular deviations, $alpha$ and $gamma$, under different working conditions.

Sign in / Sign up

Export Citation Format

Share Document