vertical accelerations
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2022 ◽  
Vol 19 (4) ◽  
pp. 34-39
Author(s):  
I. O. Chernyaev ◽  
S. A. Evtyukov

 Developments in adaptive systems for maintenance and repair of automotive vehicles set the task of monitoring the conditions of their operation. One of the main factors determining these conditions is the type of road surface.The article describes the results of identification of the type (and condition) of the road surface obtained by theoretical and experimental methods based on the analysis of vertical accelerations recorded on the vehicle body.The purpose of research was to provide a possibility of continuous monitoring of the type of road surface on which a vehicle is driving, with the subsequent application of the obtained data to correct maintenance intervals. The results of experiments have shown the dependence of the vertical acceleration of the body on the micro-profile of the road surface. The described experimentally obtained profiles of vertical accelerations refer to different types of road surface in different conditions. For quantitative assessment, it is proposed to calculate the average level of accelerations as an integral average over a certain time interval.The results of the experiments have allowed to substantiate the empirical dependence of the average level of accelerations on speed of a vehicle. Based on this dependence, a method is proposed for recalculating the current values of the average levels of accelerations obtained at different speeds into values adjusted to the base speed to ensure the possibility of their comparison.It is shown that based on the values of average acceleration levels obtained through operation monitoring regarding a previously known type of road surface, it is possible to determine its condition. A short algorithm is formulated for practical implementation and assessment of road conditions of traffic flows. As for hardware, it is proposed not to equip a vehicle with additional sensors but to use operational standard accelerometers as part of in-vehicle emergency call systems, e.g., ERA-GLONASS equipment units. 


Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 76
Author(s):  
Roberto Sañudo ◽  
Ignacio Jardí ◽  
José-Conrado Martínez ◽  
Francisco-Javier Sánchez ◽  
Marina Miranda ◽  
...  

This manuscript presents the first measurement program and data collection on the Dinatrans track transition solution after it was installed in a track section in the north of Spain (Galicia). The Dinatrans solution was created to address the limitations of several track transition solutions. This novel solution consists of two inner and outer rails from slab track to ballast track, pads with different stiffness over sleepers of variable lengths installed from ballast track to slab track, and a simple substructure formed by non-structural concrete poured over the natural ground. The main objective of this research was to assess the suitability and the initial performance of the Dinatrans track transition solution. The measured variables for these initial real-world tests were vertical accelerations on sleepers, shear stress on rails, vertical displacements on rails and vertical displacements on sleepers. All measurements of these variables were obtained in an in-situ program by installing vertical accelerometers and LVDTs on the track structure and extensometer gauges on the rails and sleepers. The methodology and the procedures followed are described. The Dinatrans initial solution was compared with the Standard solution used in Spain using these initial measurements. This field analysis provides an initial understanding of the performance of the new track transition. Further measurements will be required to check the track transition performance over the long term; however, no maintenance works have been necessary since construction (2016).


Author(s):  
H Allaka ◽  
A Levy ◽  
D Levy ◽  
T Triebitz ◽  
M Groper

This study focuses on developing a control system to enhance the seaworthiness of Autonomous high-speed Planing Crafts (APCs). APCs operating at high-speed in a seaway encounter very high vertical accelerations which pose a hazard to payload and crafts' structural integrity. Therefore, for safety operation of APCs in a seaway it is proposed to employ a system termed vision-aided speed modulation system (VSMS). The proposed VSMS employs an embedded analytical tool termed Motion Assessment of Planing Craft in a Seaway (MAPCS) for the prediction of vertical accelerations and angular velocities, the APC might encounter in the incoming waves. As a response to the MAPCS predicted values the VSMS speed setting module modulates the craft's forward speed. All modules of the VSMS are presented together with their validation and system's preliminary operational results. It is concluded that VSMS might be an essential tool to considerably enhance the operational ability of APCs. 


Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8230
Author(s):  
Andrzej Zuska ◽  
Damian Frej ◽  
Jerzy Jackowski ◽  
Marcin Żmuda

This paper deals with the issues of the impact of vertical vibrations on a child seated in a child seat during a journey. Its purpose was to assess the impact of fastening the child seats and road conditions on the level of vibrations recorded on child seats. The paper describes the tested child seats, the methodology of the tests and the test apparatus included in the measuring track. The tests were carried out in real road conditions where the child seats were located on the rear seat of a passenger vehicle. One was attached with standard seat belts, and the other with the ISOFIX base. When driving on roads with three types of surface, the following vertical accelerations were measured: seat of the child seats, the rear seat of the vehicle and the ISOfix base. The recorded accelerations were first analyzed in the time domain and then in the frequency domain. Three indexes (r.m.s, rmq and VDV) were used to assess the vibration comfort. Research has shown that the classic method of fastening a child seat with standard seat belts is more advantageous in terms of vibration comfort. Calculated indicators confirmed the negative impact of separating the child seat from the rear seat of the vehicle using the IQ ISOFIX base.


Author(s):  
Р.В. Борисов ◽  
А.А. Лузянин

Настоящая статья является пятой из цикла статей, посвященных корректировке кодекса ИМО по остойчивости в части ограничений продольной качки. В ней рассмотрены подходы к ограничениям по погоде из условий, возникающих при продольной качке для судов различных типов и предложены критерии оценки этих явлений на нерегулярном волнении разной интенсивности. На основании выполненных систематических расчетов продольной качки на нерегулярном волнении получены зависимости вертикальных ускорений по длине судна от скорости и интенсивности волнения для транспортных судов. Полученные формулы позволяют оценить указанный показатель мореходности. При этом ставится цель расширения нормативной базы для обоснованного назначения эксплуатационных ограничений по погоде и району плавания судов при совершенствовании Правил Российского Морского Регистра Судоходства на основе общего подхода к нормированию мореходности, со­гласующегося с методикой разработки новой Международной конвенции о грузовой марке 2000. Предлагаемый подход к определению дополнительных критериев мореходности для оценки эксплуатационных ограничений судов по погоде из условий мореходности может быть использован на практике для совершенст­вования нормативных требований Регистра. This article is the fifth in a series of articles devoted to the adjustment of the IMO stability code in terms of pitching limitations. It considers approaches to weather restrictions based on the conditions arising during pitching for ships of various types and proposes criteria for assessing these phenomena on irregular waves of different intensities. On the basis of the performed systematic calculations of pitching on irregular waves, the dependences of vertical accelerations along the length of the vessel on the speed and intensity of waves for transport vessels were obtained. The formulas obtained make it possible to estimate the specified indicator of seaworthiness. At the same time, the goal is to expand the regulatory framework for the justified assignment of operational restrictions on the weather and the area of navigation of ships while improving the Rules of the Russian Maritime Register of Shipping on the basis of a general approach to the regulation of seaworthiness, consistent with the methodology for the development of a new International Convention on Load Mark 2000 . The proposed approach to the definition of additional seaworthiness criteria for assessing the operational limitations of ships by weather based on seaworthiness conditions can be used in practice to improve the regulatory requirements of the Register.


2021 ◽  
Author(s):  
Konstantin I. Matveev

An effective method to reduce ship drag is to supply air under specially profiled bottom with the purpose to decrease wetted surface area of the hull and thus its water resistance. Although such systems have been installed on some vessels, the broad implementation of this technique has not yet occurred. A major problem is how to sustain air lubrication in rough water. Modeling of air-ventilated flows is challenging, but modern computational fluid dynamics tools can provide valuable insight. In this study, a wide-beam, shallow-draft hull with a bottom air cavity is considered. This hull imitates a semi-planing boat that can be used for fast transportation of cargo from large marine vessels to shallow shores. To simulate fluid flow around this hull in calm water and head waves, as well as heave and pitch motions of the boat, CFD software Star-CCM+ has been employed. It is found that the air cavity effectiveness decreases in waves; vertical accelerations exhibit high-frequency oscillations; and heave, pitch and vertical accelerations increase, while time-averaged heave, pitch and added drag show non-monotonic behavior with increasing wave amplitude. The air-cavity hull also demonstrates substantially lower vertical accelerations in waves in comparison with a similar solid hull without bottom recess. Time histories of kinematic parameters and distributions of flow field variables presented in this paper can be insightful for developers of air-cavity hulls.


Author(s):  
Priscilla Lightsey ◽  
Yonghee Lee ◽  
Nancy Krenek ◽  
Pilwon Hur

Abstract Background Physical therapy treatments incorporating equine movement are recognized as an effective tool to treat functional mobility and balance in children with cerebral palsy (CP). To date, only a few studies examined kinematic outputs of the horses and children when mounted. In this pilot study, to better understand the effectiveness of this type of treatment, we examined the interaction between the horses and children with CP during physical therapy sessions where equine movement was utilized. Methods Four children with CP participated in eight physical therapy sessions incorporating hippotherapy as a treatment intervention. Functional mobility was assessed using the Timed Up Go or the 10 m Walk Test. Inertial measurement unit sensors, attached to children and horses, recorded movements and tracked acceleration, angular velocity, and body orientation. Correlation between vertical accelerations of children and horses were analyzed. In addition, peak frequencies of vertical accelerations of children and horses were compared. Results Functional tests modestly improved over time. The children’s movements, (quantified in frequency and temporal domains) increasingly synchronized to the vertical movement of the horse’s walk, demonstrated by reduced frequency errors and increased correlation. Conclusions The findings suggest that as the sessions progressed, the participants appeared to become more familiar with the horse’s movement. Since the horse’s gait at a walk mimics the human gait this type of treatment may provide individuals with CP, who have abnormal gait patterns, an opportunity for their neuromuscular system to experience a typical gait pattern. The horse’s movement at the walk are consistent, cyclical, rhythmical, reciprocal and multi-dimensional, all of which can facilitate motor learning. The increased synchronization between horse and the mounted participant suggests that physical therapy utilizing equine movement is a viable treatment tool to enhance functional mobility. This study may provide a useful baseline for future work. Trial registrationTexas A&M University Institutional Review Board. IRB2018-0064. Registered 8 March 2018. Link: https://rcb.tamu.edu/humans/irb and https://github.com/pilwonhur/HPOT


2021 ◽  
pp. 1-20
Author(s):  
Michael R. Davis

High-speed ferries of around 100 m length cruising at around 40 knots can cause significant passenger discomfort in head waves. This is due to the frequencies of encountering waves, of maximum hull response to encountered waves and of maximum passenger discomfort all falling within a similar range. In this paper, the benefit obtained by fitting active T-foils and stern tabs to control heave and pitch in head waves is considered. Ship motion responses are computed by numerical integration in the time domain including unsteady control actions using a time domain, high-speed strip theory. This obviates the need to identify transfer functions, the computed time responses including nonlinear hull immersion terms. The largest passenger vertical accelerations occur at forward locations and are best controlled by a forward located T-foil acting in combination with active stern tabs. Various feedback control algorithms have been considered and it is found that pitch damping control gives the greatest improvement in passenger comfort at forward positions. Operation in adaptive and nonlinear modes so that the control deflections are maximized under all conditions give the greatest benefit and can reduce passenger motion sickness incidence (MSI) by up to 25% in a 3-m head sea on the basis of International Organization for Standardization (ISO) recommendations for calculation of MSI for a 90-minute seaway passage.


Author(s):  
O. Wage ◽  
M. Sester

Abstract. In contrast to cars, route choices for cycling are barely influenced by the respective traffic situation, but to a large extent by the routes’ comfort. Especially in urban settings with several alternatives, segments with many or long stops at traffic lights and badly maintained roads are avoided due to a low comfort and cyclists vary from the shortest route. This fact is only indirectly considered in common navigation applications.This work aims to integrate surface roughness measurements collected from diverse bicycles to a joint scale via a least-squares adjustment. Data was collected using smartphones, which were mounted to bike hand bars and measured positions and vertical accelerations on user’s trips. As this way sensed roughness also depends on the bike setting and type, the resulting values would be different for different users. Thus, this paper presents a novel approach to harmonize observations from differing sensitive setups. The basic concept idea of bundle block adjustment is adapted to calibrate a basic scale model and in parallel adjust the observations of surface roughness to a common scale.This way a crowd-sourced roughness map can be generated. Such a map can be used to enrich bike focused routing services and thus encourage cycling in daily live. In addition, it can also be used to derive hints for infrastructure servicing.


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