Acceleration Characteristics Research Articles

Investigation on Vibration Influence Law of Double-Shield TBM Tunnel Construction

Double-shield TBM is more efficient than shield tunnel construction in hard rock strata. It is widely used in subway tunnel construction, such as in Qingdao and Chongqing in China. However, construction vibration problems caused by double-shield TBM critically affect human comfort in surface buildings. In order to study the vibration influence law of double-shield TBM, the on-site monitoring plan of double-shield TBM is developed, relying on a tunnel section of Qingdao Metro Line 4. Then, the vibration monitoring results are analyzed, and the time domain and frequency domain characteristics of vibration acceleration are obtained. Subsequently, taking vibration peak acceleration as the research object, the transverse and longitudinal vibration laws of double-shield TBM construction are studied. Finally, according to the standard of human comfort in buildings, the vibration influence ranges of double-shield TBM construction are obtained. The research results can provide a reference for the vibration effect of double-shield TBM passing through houses, highways and bridges. Moreover, it can also provide a basis for the disputes that double-shield TBM tunnel construction affects the lives of inhabitants.

Real-Time Detection of Lower Limb Training Stability Function Based on Smart Wearable Sensors

The research of smart wearable sensors in limb training has great application significance. In the face of real-time detection requirements, this paper proposes a hardware solution for the stability function of lower limb training based on the theory of intelligent wearable sensors. For the specific implementation circuit of the device, considering the reliability of the system, the system implements antijamming design for the hardware circuit from three aspects: adding decoupling capacitors, optimizing layout and wiring, and rationally grounding the hardware circuit, and performs moving average filtering on the collected sensor data to remove noise, which solves the problem of sensor data precision issues. During the simulation process, by analyzing the changes of acceleration, angular velocity, and attitude angle under different lower limb training activities and different wearing positions, the characteristics of stability combined acceleration, combined angular velocity, and attitude angle were constructed, and the stability mean, variance, and attitude angle were extracted. The experimental results show that the extracted 57 feature dimensions are first reduced to 21 dimensions by the principal component analysis algorithm, and then, the optimal feature subset is selected by the encapsulation method, and the dimension is reduced to 9. The proposed multifeature fusion algorithm has higher accuracy, and the maximum has increased by 6.5%, effectively improving the accuracy of the lower limb training stability function detection algorithm.

Correlation Investigation of Wind Turbine Multiple Operating Parameters Based on SCADA Data

The primary wind turbines’ in-service performance evaluation method is mining and analyzing the SCADA data. However, there are complex mathematical and physical relationships between multiple operating parameters, and so far, there is a lack of systematic understanding. To solve this issue, the distribution of wind turbines’ operating parameters was first analyzed according to the characteristics of the energy flow of wind turbines. Then, the correlation calculation was performed using the Spearman correlation coefficient method based on the minute-level data and second-level data. According to the numerical characteristics of the nacelle vibration acceleration, the data preprocessing technology sliding window maximum (SWM) was proposed during the calculation. In addition, taking temperature correlation as an example, two-dimensional scatter (including single-valued scatter) and three-dimensional scatter features were combined with numerical analysis and physical mechanism analysis to understand the correlation characteristics better. On this basis, a quantitative description model of the temperature characteristics of the gearbox oil pool was constructed. Through this research work, the complex mathematical and physical relationships among the multi-parameters of the wind turbines were comprehensively obtained, which provides data and theoretical support for the design, operation, and maintenance.

Hydrodynamic and Flow Field Characteristics of Water Jet Propulsion under Mooring Conditions

The acceleration characteristics of a water jet-propelled ship during startup are related to its performance under mooring conditions. Water jet propulsion cavitation during startup increases the vibration and noise of the whole ship. Therefore, accurately predicting and analyzing the performance, hydrodynamics and flow field characteristics of water jet-propelled ships under mooring conditions can help elucidate the startup characteristics of the ships and optimize their acceleration strategies. In this study, the hydrodynamic and flow field characteristics of water jet propulsion and water jet propulsion ships under mooring conditions were studied using three-dimensional numerical modeling. First, the hydrodynamic performance of the water jet propeller was analyzed, and the relevant flow field law was derived. Then, the hydrodynamic performance, internal and external flow field characteristics, pulsation pressure and flow rate at the nozzle, and pulsation pressure at the monitoring points around the impeller of the water jet propulsion ship model were analyzed under mooring conditions. We obtained the open-water law for the water jet propeller and the hydrodynamic force and flow field law for a two-pump water jet propulsion ship. The ship model developed in this study provides a good theoretical foundation for further research on water jet propulsion.

Application of Stewart Platform in the Low-Frequency Vibration Characteristic Test of Space Truss Deployable Antenna on Satellite

The space truss deployable antenna has low natural frequency, multi-closed-loop, and multiredundant structure characteristics, which is a kind of flexible antenna. It is hard to obtain the vibration characteristics under low frequency by finite element analysis or conventional shaking table test. To verify the structure characteristics of the antenna in the folded state below 2 Hz, a low-frequency vibration system is established based on the 6-DOF Stewart platform. Rotation matrix analysis method was adopted to obtain the platform’s velocity and acceleration characteristics. Then, a low-frequency vibration test was carried out on the platform. The results show that the natural frequency of the antenna is 1.51 Hz and the maximum dynamic displacement is 140.6 mm, which provides a certain foundation for the further development of the space truss antenna.

Self-propelled drops on hydrophilic microfinned surfaces

Straight and curved hydrophilic microfinned surfaces are prepared in this work by photolithography and sputtering coating techniques using silicon wafers as substrates. The behavioral characteristics of drops on these surfaces are discussed by using image-processing technology. The experimental results show that when a drop is placed on the straight microfinned surface, the front contact line of the drop can move, while the rear contact line remains fixed. On the curved microfinned surface, however, both the front and the rear contact line can move. The drop can be self-propelled directionally from the region with larger roughness to the region with smaller roughness. The characteristics of velocity and acceleration on both surfaces are analyzed. A theoretical model is proposed by analyzing the energy conversion and compared with the experimental results. This study provides a novel microstructured surface for enhancing the heat-transfer performance of condensers.

Methods for Identification of Complex Industrial Control Objects on Their Accelerating Characteristics

Theoretical identification methods for complex industrial control objects give very cumbersome and complex mathematical relations, the use of which for practical purposes is not constructive. In this regard, methods for obtaining mathematical models based on experimental data have now become the main focus of identification theory. In this paper is described the method of identification of industrial control objects developed according to their acceleration characteristics. The structure of the object under study is determined by the type of amplitude-phase frequency response and dynamic parameters are determined by experimental data. The high adequacy of the method is confirmed by similar studies on known (reference) models. The scientific novelty of the work consists in development of a new method for identifying complex industrial control objects by their acceleration characteristics.

Indoor Localization Using Mind Evolutionary Algorithm-Based Geomagnetic Positioning and Smartphone IMU Sensors

With the pervasiveness and ubiquitous distribution of the magnetic field in indoor environments, indoor localization using magnetic positioning (MP) has attracted considerable attention. This work concentrates on the MP and pedestrian dead reckoning (PDR) method, and constructs a fusion system for smartphones using MP and PDR based on the extended Kalman filter (EKF). The mind evolutionary algorithm (MEA) is introduced to search for the optimal magnetic position based on a heuristic searching strategy, which uses the similartaxis and dissimilation for the evolutionary operation. In the PDR module, the acceleration characteristics of different walking patterns are analyzed and the corresponding features are extracted. The enhanced genetic algorithm-based extreme learning machine (EGA-ELM) is adopted to train these features and address the gait recognition problem of different walking patterns. Finally, to obtain a lightweight and high-precision fusion method, MEA-based MP is integrated with PDR based on the EKF. Extensive experiments are conducted to evaluate the proposed methods. The testing results showed that MEA-based MP can obtain a location error within 2.3 m and steps can be recognized with a mean accuracy of 95% when different users participate in testing. The positioning results after fusion with PDR reveal that the mean location error and root-mean-square error (RMSE) are 1.25 m and 1.53 m respectively, which outperforms the MP, PDR, MP and PDR fusion methods using improved particle filter (IPF) and genetic particle filter (GPF).

The System Simulating the State of the Objects and the Process of Their Monitoring with the Help of the Convolutional Neural Network

In this paper, the implementation of the system simulating the states of the objects and the process of their monitoring is considered. The tasks for this system include detection and diagnosis of defective states of the studied objects. In order to configure flexibly the system and to reduce the human factor, the use of neural networks is proposed. The model of the complex for the object monitoring simulation is presented. It is introduced in the form of a software application and is tested as a part of a diagnostic system fitted in the railroad track measuring car. This system makes it possible to determine the dimensions of artificial structures on the railway and, most importantly, to find the sites where the standard overall dimensions are reduced due to the deviation of separate structural elements from their designed position. The algorithmic and mathematical support employed in this paper allows determining the geometric (dimensions and position in space), the kinematic (speed and direction of movement) and the dynamic (motion acceleration, unredeemed car acceleration) characteristics of both moving and stationary objects. During its implementation, such system takes the form of a software and hardware complex equipped with movable and fixed photodetectors, depending on the set of tasks to be solved. A characteristic feature of this study is that the methods and the algorithms it proposes for image processing can be adapted and used in building digital twins of transport infrastructure objects including not only the railway tracks but also various technological and service facilities. Due to this approach, the input of the nodal points of infrastructure objects and their elements can be automated into the project design scheme, exponentially reducing the laboriousness of creating primary models. The aggregation of the proposed methods with the capabilities of modern neural networks improves the primary image processing speed on the side of the client application, without fully occupying the data transfer channel between different modules of the information-measuring complex.

A Comparative Evaluation of the Total Cost of Ownership between Electric Two-Wheelers and Motorized Two-Wheelers from an Indian Perspective

A comparative assessment of the total cost of ownership (TCO) is necessary to quantify overall costs and assess the economic viability of electric two-wheelers (E2W) compared with motorized two-wheelers (M2W). In this regard, TCO models specifically for two-wheelers were developed in this study to compare the TCO of E2W and M2W under the prevailing market conditions. The TCO model has four cost components, namely, acquisition costs, operating costs, maintenance costs, and resale value. The TCO was calculated considering a 10-year assessment period with 2021 as the base year. The available E2W and M2W alternatives in the Indian market were classified into low-performance (Category A) and high-performance (Category B) two-wheelers based on their power output and acceleration characteristics. The TCO estimates were also evaluated for three different average daily distances traveled ( ADDT): 10 km/day, 30 km/day, and 50 km/day. The results revealed that the TCO estimates for E2W vary from ₹0.67/km for an ADDT of 50 km/day for Category A E2W during the base year condition to₹7.66/km for an ADDT of 10 km/day for Category B E2W at the end of the assessment period. Further, the payback periods for different scenarios were also estimated and compared. The acquisition and battery replacement costs are critical factors for potential users of E2W, and act as a significant barrier to the widespread adoption of E2W in India. Finally, it can be concluded that E2W are an economically viable alternative compared with M2W, with payback periods ranging from one year to eight years in the Indian context.

Color tissue doppler imaging of tricuspid annular plane systolic and diastolic excursion in children: A comparison of normal, volume-overloaded and pressure overloaded right ventricles.

Tricuspid annular plane (TAP) systolic excursion (TAPSE) is a reproducible M-mode parameter for the measurement of longitudinal shortening of the right ventricle (RV). To date, all attention has been focused on the systolic excursion of TAP and the diastolic excursion of the annular plane back to the base has been ignored. This study aims to compare the quantitative (excursion, slope, and duration) and qualitative (velocity, acceleration, and indentation) characteristics of TAP systolic and diastolic excursion, using color tissue Doppler imaging, in three groups of children with normal RV (NORV), volume overloaded RV (VORV), and pressure overloaded RV (PORV) and normal pulmonary arterial pressure. A prospective case-control study was performed in three groups of children with normal heart, VORV and PORV. TAPSE and tricuspid annular plane diastolic excursion (TAPDE) were quantitatively and qualitatively analyzed and compared between the three groups. Statistical analysis was performed using IBM SPSS Statistics for Windows. TAPSE, TAPDE, TAPSE slope, TAPSE slope/TAPDE slope, TAPDE duration and TAPDE duration/RR interval were lower in PORV (TAPSE: PORV: 14.45±4.30, NORV: 20.45±5.46, P=.003, TAPDE:PORV: 14.39±4.61, NORV: 20.28±5.65, P=.004, TAPSE slope:PORV: 4.79±1.40, NORV: 7.15±1.98, P=.001, .001, TAPDE duration:PORV: 201.1±87.9 ms, NORV: 292.1±97.9, P=.006, TAPDE duration/RR interval: PORV: .37±.09, NORV: .48±.08, P=.0002). Pressure-overload on RV produced more impairment of TAPSE and TAPDE patterns than volume overload. Values of TAPSE and TAPDE in patients with VORV and PORV stay in two ends of the normal spectrum. The harmful impact of pre-tricuspid volume overload seems to be less than the post-tricuspid volume overload.

The response law of far-field seismic ground motion of the Wenchuan earthquake and its damaging mechanism in the Loess Plateau

A series of housing collapses and other serious damage was caused by the 2008 Wenchuan MS 8.0 earthquake in the seismic intensity Ⅵ areas of the Loess Plateau, which is hundreds of kilometers away from the epicenter, and which showed a remarkable seismic intensity anomaly. The seismic disasters are closely related to the seismic response characteristics of the site, therefore, the systematic study of the far-field seismic response law of the Wenchuan earthquake in the Loess Plateau is of great significance to prevent the far-field disaster of great earthquake. In this paper, the seismic acceleration records of several bedrock stations and loess stations from the seismogenic fault of the Wenchuan earthquake to the Loess Plateau were collected, and the attenuation law of ground motion along the propagation path and the characteristics of seismic response on the loess site are studied, and the mechanism of amplification effect of ground motion is analyzed based on the dynamic feature parameters of the loess site obtained through the HVSR method. Taking a typical loess site of thick deposit as the prototype, a series of shaking table tests of dynamic response of loess site models with different thicknesses were carried out. Amplification effect, spectral characteristics of acceleration in model sites were analyzed under the action of a far-field seismic wave of the Wenchuan earthquake. The results show that seismic attenuation on the propagation path along the NE strike of the seismogenic fault to the Loess Plateau is slower than that in other directions, and the predominant period range of ground motion on bedrock site of the Loess Plateau presents broadband characteristics. Because the natural periods of loess sites with thick deposits are within the predominant period range of bedrock input wave, loess sites appear significant amplification effect of ground motion, the horizontal acceleration of ground motion exceeds 0.1 ​g, the seismic intensity reaches 7°. The thicker the loess deposit is, the more significant the change of spectral characteristics of ground motion on loess sites, and the narrower the predominant period range of ground motion becomes, and the closer it is to the natural period of loess sites. Therefore, for some old houses on thick loess sites, the poor seismic performance and strong seismic response eventually led to their collapses and damages because their natural periods are very close to the predominant period of ground motion of the Wenchuan earthquake on thick loess sites; For these damaged high-rise buildings, the resonance effect might be the main reason for their damages because their natural periods are included in the predominant period range of ground motion of the Wenchuan earthquake on thick loess sites.These research results would provide a basis for seismic disasters prediction and evaluation and seismic design of construction engineering in the Loess Plateau.

Full-Scale Measurements of Translational and Torsional Dynamics Characteristics of a High-Rise Building during Typhoon Sarika.

The field measurement of wind-induced response is of great significance to the wind resistance design of high-rise buildings, in particular torsional responses measured from high-rise buildings under typhoons. The measured high-rise building, with a height of 108 m, has 32 stories and is supported by giant trusses with four massive columns. Acceleration responses along translational and torsional directions were monitored synchronously and continuously during the passage of Typhoon Sarika on 18 October 2016. The wind speed and wind direction at the height of 115 m, the translational accelerations on a total of six floors and the angular accelerations on a total of four floors were recorded. The time and frequency domain characteristics of translational acceleration and torsional angular accelerations were analyzed. The amplitude-dependent translational and torsional modal frequencies of the measured building were identified by NExT-ERA, SSI, and RDT methods. The full-scale study is expected to provide useful information on the wind-resistant design of high-rise buildings in typhoon-prone regions.

Shaking table test for seismic optimization of soil slope reinforced by new EPS pile under earthquake

To explore the optimal seismic performance of new EPS pile, we carried out a series of shaking table test by comparing different pile types. We measured and obtained the seismic data with various attributes, such as the characteristic image of different probability horizontal seismic action, acceleration and dynamic soil pressure. By analyzing the time-domain characteristics of multi-attribute data such as deformation characteristics and acceleration, we revealed the instability mode of the slope model and the regional response characteristics of particle spatial position. Based on the Fast Fourier Transform (FFT) and Statistical Probability Sperm Matrix (SPSM), we proposed the damage level correlation between the spectral characteristics of acceleration and dynamic soil pressure. We obtained the relationship between the variation of the frequency and specific period between acceleration and dynamic soil pressure at different seismic stages through in-depth study, and then calculated the regional differences of spectrum displacement (Sd) by using Seism Signal. In the frequency domain of acceleration and dynamic soil pressure signals, the predominant frequencies were mostly concentrated in 0.5–8 Hz. Under high seismic acceleration, the amplitude frequency of acceleration spectrum of conventional pile and EPS pile was both 1.51 Hz, and the dominant frequency of dynamic soil pressure was significantly different. There was a positive correlation between seismic acceleration and dynamic soil pressure. The shift of frequency profile and main frequency band of EPS pile was mainly caused by the propagation stage after the acceleration main shock. Under high seismic acceleration, the deformation of EPS pile and conventional pile occurred to some extent. EPS plate was used as the damping layer to buffer and dissipated the deformation of the slope under earthquake, and its effect was linked to the seismic data attributes. The spectral displacement of EPS pile was reduced as a whole was higher than that of conventional pile. The slip surface of pile body was sensitive to earthquake, and it was easy to become the weak seismic link of the EPS pile. These results are helpful for us to provide a theoretical basis for improving the reliability optimization design of dynamic parameters of the pile structure.

Research and Analysis of Driving Behavior Characteristics Under Anger Emotion

With the rapid progress of society, the number of automobiles in our country is also increasing day by day. The resulting traffic jams and traffic accidents are also increasing. Under the dual pressure of work and life, drivers tend to accumulate some negative emotions, resulting in a certain degree of anger in the driver. When a driver drives with a bad mood like anger, it is likely to cause a car accident. Therefore, it is particularly necessary to study the driving behavior characteristics of drivers in the state of anger. In this paper, the driver’s anger is stimulated by means of emotion stimulation, and the driving behavior characteristics of the driver under the anger are collected through a simulated experimenter. By analyzing the characteristics of speed and acceleration, the relationship between speed characteristics and dangerous driving behaviors under anger is discussed. Finally, through the detection and analysis of the speed characteristics under anger, it can be seen that the perception of the driver’s actual behavior and the recognition of emotions while driving are to provide an early warning for judging whether the driver is angry and potentially dangerous driving behavior, thereby reducing accidents rate key.

Acceleration Characteristics of Ions Exhausted from Short Pulse Coaxial Laser-Assisted Pulse Plasma Thruster

Acceleration Characteristics of Ions Exhausted from Short Pulse Coaxial Laser-Assisted Pulse Plasma Thruster

Vibration suppression of omni-directional mobile robots for inspecting outdoor infrastructure facilities

Infrastructure facilities have been deteriorating and require a vast number of inspections conducted by skilled engineers. Inspection robots are required because of a shortage of skilled engineers. In order to improve the inspection efficiency of outdoor infrastructure facilities, an omni-directional mobile robot that can move freely in all directions has been investigated. However, it is necessary to design a vibration isolation mechanism because the accuracy of the positional inspection of underground objects is adversely affected by vibration in an outdoor environment. We have constructed an experimental setup to evaluate the vibration properties of the wheel. The acceleration characteristics due to the difference between the direction of movement and the speed of the omni-wheel have been evaluated. It was confirmed that periodic vibration occurred by each moving direction of the Omni wheel.

Sensitivity Enhancement of a Semicircular Curved Hetero-Core Optical Fiber Accelerometer With Low Cross-Axis Sensitivity

In this article, the frequency, amplitude, and cross-axis sensitivity characteristics of a hetero-core fiber optic accelerometer subjected to mechanical vibrations are presented. The proposed accelerometer is based on a fixed-support structure and can be used for structural health monitoring. It consists of a semicircular curved hetero-core optical fiber with both ends fixed to a base, which operates as a vibration detector. To increase its sensitivity and reduce its cross-axis sensitivity, a hetero-core portion is placed near one of the fixed ends. By fabricating an ideal semicircular beam-shaped acceleration sensor with both ends fixed, good agreement between the experimentally obtained spectrum results and finite element analysis results when the accelerometer is subjected to mechanical vibrations is observed. The accelerometer’s sensitivity is clearly stable at frequencies less than approximately a quarter of the first natural frequencies of 1810, 850, and 350 Hz with sensitivities of 1.45 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 10^{-3}$ </tex-math></inline-formula> , 2.80 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 10^{-3}$ </tex-math></inline-formula> , and 6.16 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 10^{-3}$ </tex-math></inline-formula> dB/g for fiber curvature radii of 7, 10, and 15 mm, respectively. Owing to its highly linear acceleration characteristics, it is possible to efficiently convert the acceleration to optical loss. The cross-axis sensitivity is in the range 4.27%–15.9%, which is better than that of previously reported accelerometer structures, which use a hetero-core fiber sensor located at the center between the two fixed ends without a free supporting point. Therefore, the proposed accelerometer, which consists only of a semicircular-shaped optical fiber, is capable of improving the sensitivity and reducing the cross-axis sensitivity by adjusting the placement of the hetero-core fiber sensor.

Assessment of the Seismic Response of Shallow Buried Elliptical Tunnels

ABSTRACT Investigating dynamic responses and damage modes of tunnels constructed in different geological conditions is of great significance to understand the damage mechanism and put forward mitigation measures. In this paper, large-scale shaking table tests with the similarity ratio of 1:12 were used to study the seismic response (acceleration and spectrum characteristics, hoop strain, dynamic earth pressure, and longitudinal strain) of shallow buried elliptical tunnels motivated by different dynamic loads. Three different conditions of tunnel section were discussed: with shock-absorbing layer (SAL), with fault, and without SAL and fault. Then the slipping and expanding displacement, dynamic stress concentration, and damage modes of the tunnel across the fault fracture zone were studied based on numerical simulations. The research results illustrate that the presence of SAL has slight influences on amplifying the peak acceleration of the excitation motions and controlling the longitudinal strain, but it could effectively mitigate the motion energy and dynamic earth pressure around tunnels; it also demonstrates that the SAL can be utilized as a damping layer to weaken the seismic waves. Additionally, tunnels in the fault fracture zone perform remarkable dynamic response than those in the normal surrounding rock; the largest slipping and expanding displacement of fault often occur at the moment when the acceleration of the excitation motion reaches its high value.

Electromagnetic Force and Mechanical Response of Turbo-Generator End Winding under Electromechanical Faults

This paper comparatively studies the electromagnetic force and mechanical response of the end winding before and after 3 kinds of typical electromechanical faults in turbo-generator. The analytical expression of electromagnetic force of end winding is derived under the composite fault of static eccentricity and rotor interturn short circuit. Meanwhile, the three-dimensional transient finite element simulation is carried on, and the frequency composition and amplitude variation characteristics of the radial, axial, and tangential electromagnetic force are analyzed for the end windings under static eccentricity, rotor interturn short circuit, and composite fault. Therefore, it provides a reference for the vibration wear detection and electromagnetic force control of the end winding. Moreover, the maximum stress and deformation of different positions on the end involute are obtained. And the three-directional vibration acceleration characteristics of the end winding are further analyzed. Finally, the distribution law of winding fatigue failure and vibration wear is acquired, which lays a foundation for the reverse suppression of end winding fatigue failure and insulation wear.