Error modeling and analysis of inclinometer based on digital accelerometer

Measuring accuracy of inclinometer based on accelerometer is mainly influenced by the adopted accelerometer sensor.To improve the measuring accuracy of the inclinometer,the structure of the measuring system is given and measuring principle is analyzed,and the error model is established in this paper.Furthermore,the model is verified by simulation and experiment,which not only gives the smallest errors of the measured pitch and roll,but also lays foundation for sensor selection,error analysis and error compensation.The results show that the error model is of practical value.

The Error Compensation of Inclinometer Based on Polynomial Fitting

In order to reduce the influence of nonlinear characteristic and temperature on the measuring accuracy of inclinometer, the application of polynomial fitting principle to compensate the measuring error of inclinometer is studied. According to the analysis of the experimental data of inclinometer, a polynomial model of the nonlinear error and the measured value is constructed, and then the relation between the coefficient of the polynomial model and the temperature is obtained by fitting, and finally the function of the measurement error of inclinometer on the measured inclination and temperature is obtained. The results show that this method is feasible and effective, which can not only reduce the influence of temperature, but also correct its nonlinear error.

Monitoring and Warning of Landslides and Debris Flows Using an Optical Fiber Sensor Technology

Landslides and debris flows are typical geo-hazards which occur in hilly or mountainous regions. Debris flows may result from landslides. Geotechnical instrumentation plays an important role in monitoring and warning of landslides and resulted debris flows. Traditional technologies for monitoring landslides and debris flows have certain limitations. The new optical fiber sensors presented in this paper can overcome those limitations. This paper presents two new optical fiber sensor systems: one is the Fiber Bragg Grating (FBG)-based in-place inclinometer for monitoring landslides and the other is the FBG-based column-net system for monitoring debris flows. This paper presents the calibration results of FBG-based in-place inclinometers in laboratory. It is found that the calibration results are in good agreement with theoretical results. Both the FBG-based in-place inclinometers and the FBG-based column-net system have been installed at a site in Weijiagou valley, Beichuan County, Sichuan Province of China. Some preliminary results have been obtained and reported in the paper. The advantages of the FBG monitoring systems and their potential applications are also presented.

Multi-type sensor placement and response reconstruction for building structures: Experimental investigations

Estimation of lateral displacement and acceleration responses is essential to assess safety and serviceability of high-rise buildings under dynamic loadings including earthquake excitations. However, the measurement information from the limited number of sensors installed in a building structure is often insufficient for the complete structural performance assessment. An integrated multi-type sensor placement and response reconstruction method has thus been proposed by the authors to tackle this problem. To validate the feasibility and effectiveness of the proposed method, an experimental investigation using a cantilever beam with multi-type sensors is performed and reported in this paper. The experimental setup is first introduced. The finite element modelling and model updating of the cantilever beam are then performed. The optimal sensor placement for the best response reconstruction is determined by the proposed method based on the updated FE model of the beam. After the sensors are installed on the physical cantilever beam, a number of experiments are carried out. The responses at key locations are reconstructed and compared with the measured ones. The reconstructed responses achieve a good match with the measured ones, manifesting the feasibility and effectiveness of the proposed method. Besides, the proposed method is also examined for the cases of different excitations and unknown excitation, and the results prove the proposed method to be robust and effective. The superiority of the optimized sensor placement scheme is finally demonstrated through comparison with two other different sensor placement schemes： the accelerometer-only scheme and non-optimal sensor placement scheme. The proposed method can be applied to high-rise buildings for seismic performance assessment.

Typology of Landslides, Investigation and Monitoring in Flysch Deposits in Albania

The development of infrastructure, energy and tourism in recent years in Albania has brought the necessity of geotechnical studies to a higher technical level. Most of these buildings （hydropower, motorway, pipeline） are built in mountainous areas with complicated geological conditions. The most complicated obstacles seem to be huge landslides, especially for those situated on flysch deposits. Most of the huge landslides were innate and active by the end of Pleistocene; however, some of them, especially those in flysch areas, are activated due to recent changes of climate and intensive man activities. Examples of re-activation of old landslides are encountered on Qukes-Qafe Pllo^e road, on Devoll river valley which are being built several hydropower and on Poli^an-Potom area where a gas line is built. These landslides are under design investigations using field and laboratory methods like drilling, inclinometers and piezometers measurement, geophysical probing, rock and soil testing. All slopes with flysch rocks in Albania have low stability because of the presence of active landslides. In any case they should be studied using advanced geotechnical methods and monitored for tong time in order to take the right protective measures.

ActiGraph GT3X determined variations in “free-living” standing,lying,and sitting duration among sedentary adults

Background:Overweight and obesity has become a serious public health problem in many parts of the world.Studies suggest that making small changes in daily activity levels such as"breaking-up"sedentary time(i.e.,standing)may help mitigate the health risks of sedentary behavior.The aim of the present study was to examine time spent in standing(determined by count threshold),lying,and sitting postures(determined by inclinometer function)via the ActiGraph GT3X among sedentary adults with differing weight status based on body mass index(BMI)categories.Methods:Participants included 22 sedentary adults(14 men,8 women;mean age 26.5±4.1 years).All subjects completed the self-report International Physical Activity Questionnaire to determine time spent sitting over the previous 7 days.Participants were included if they spent seven or more hours sitting per day.Postures were determined with the ActiGraph GT3X inclinometer function.Participants were instructed to wear the accelerometer for 7 consecutive days(24 h a day).BMI was categorized as:18.5 to【25 kg/m2as normal,25 to【30 kg/m2as overweight,and≥30 kg/m2as obese.Results:Participants in the normal weight(n=10)and overweight(n=6)groups spent significantly more time standing(after adjustment for moderate-to-vigorous intensity physical activity and wear-time)(6.7 h and 7.3 h respectively)and less time sitting(7.1 h and 6.9 h respectively)than those in obese(n=6)categories(5.5 h and 8.0 h respectively)after adjustment for wear-time(p【0.001).There were no significant differences in standing and sitting time between normal weight and overweight groups(p=0.051 and p=0.670 respectively).Differences were not significant among groups for lying time(p=0.55).Conclusion:This study described postural allocations standing,lying,and sitting among normal weight,overweight,and obese sedentary adults.The results provide additional evidence for the use of increasing standing time in obesity prevention strategies.

Environmental simulation platform and its application to geodesic instruments for a performance study

In this study,an environmental simulation platform(ETS-02)was constructed for high-precision geodesic instruments(e.g.,absolute/relative gravimeters and inclinometers),to test the disturbances caused by environmental fl uctuations.The outer layer of the platform was constructed with two sets of rectangular electromagnetic coils,which generated the required magnetic fi eld when current was applied.The inner layer was a closed cabin in which radiators were distributed such that the temperature of the experimental space inside the cabin could be controlled,by energy exchange between the radiators and a thermal controller through the fl owing liquid.A high-precision hexapod was used to simulate the tilt-related eff ect.The platform was capable of adjusting temperatures within a dynamic range of 0℃-70℃ at a resolution of 0.01℃.The noise of the power-spectrum density when the cabin was set to room temperature was measured as 0.03℃/Hz^(1/2) at 1 mHz.The magnetic field simulation had a dynamic range of±300μT and stability of 20 nT.The resolution of the ground-tilt simulation was 1 arc s.The inner space of the platform had a volume of approximately 5 m^(3),which is sufficient for most types of instruments to be tested for a general environmental coupling effect.To illustrate the application of the platform,a dual-axis inclinometer was built and tested carefully with the platform,and the accuracy of the calibration factors was found to be signifi cantly improved.

Counting Steps in Research: A Comparison of Accelerometry and Pedometry

The objective of this study was to assess the validity of the step count functions in Actical accelerometers and activPAL inclinometers, compared with pedome-ter-derived step count data. Firstly, directly observed step counts over 3 treadmill speeds were compared with steps collected from 3 pedometers, accelerometers, and inclinometers in 10 adults. Secondly, step count data were derived from 22 participants who wore a pedome-ter, accelerometer, and inclinometer over 48 hours. Agreement between measurement tools was determined. All monitors appropriately measured steps in the labo-ratory conditions. In free living conditions, the mean percentage differences with pedometer-determined step counts were -7.3% and 7.0% for the Actical and ac-tivPAL monitors, respectively. With the exception of slow walking for the Actical units (ICC < 0.001), acceptable reliability was found within units for all treadmill speeds, and across units during the free living condition. The 95% prediction interval ranges were wide, ranging from -68.8% to 54.2% for the Acticals, and from -39.1% to 53.2% for the activPALs. Step counts gathered from Actical and activPAL units should not be used interchangeably with pedometer-derived step count data.

Quaternion Realization of Mobile Weapon Aiming Stabilization

Quaternion realization of aiming stabilization of the mobile weapon is considered.Gyro compassing combined with an inclinometer is used for the measurement of the initial chassis orientation in respect of the geographical north and the horizontal plane.The same 3D gyroscope is used for the measurement of the subsequent incremental change of the chassis orientation.The goal of the proposed stabilization is to maintain the aiming geo coordinates generated by the fire control system while moving in an uneven terrain.

Transportation infrastructure settlement and heave distress:challenges and solutions

Transportation agencies spend millions of dollars annually to repair civil transportation infrastructure including pavements,earth structures and approach slabs distressed by soft compressible soils and expansive soils.Several research studies performed at the University of Texas at Arlington(UTA) focused on stabilizing these problematic soils so that they will provide better and more stable support to the transportation infrastructure.This paper focuses on a summary of two major distresses and mechanisms,and remedial measures for addressing these distress problems.A combined lime-cement stabilization method is fully evaluated in providing better support of pavement infrastructure,and these results are described here.Another major transportation infrastructure problem involving bridge approach slabs requires different treatment methods,and these results are briefly described.As a part of the recently completed research study assessments,both shallow and deep soil treatment methods for stabilizing soils are fully evaluated for their effectiveness in arresting the distress posed to the pavements and bridge approach slabs.These results along with a few future research needs are presented in this paper.

Measurement errors and correction of the UAT-2 ultrasonic anemometer

Two kinds of measurement errors have been observed in the recently developed UAT-2 ultrasonic anemometer.One is the flow distortion produced by a"blocking effect",and the other is the angle of attack caused by the vertical misalignment of the instrument.Here,we study these errors and discuss the possible correction methods.Via a wind tunnel experiment and numerical simulation,a 3D calibration matrix was developed to correct the"blocking effect".In the field test,the angle of attack was detected by an inclinometer settled on the reference plane of the anemometer,and the instrumental misalignment or tilt was corrected by a coordinate transformation.The combined use of an inclinometer and the proposed correction method may help find a new approach for vertical velocity correction.