• Title/Summary/Keyword: free lateral movement

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Total reference-free displacements for condition assessment of timber railroad bridges using tilt

  • Ozdagli, Ali I.;Gomez, Jose A.;Moreu, Fernando
    • Smart Structures and Systems
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    • v.20 no.5
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    • pp.549-562
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    • 2017
  • The US railroad network carries 40% of the nation's total freight. Railroad bridges are the most critical part of the network infrastructure and, therefore, must be properly maintained for the operational safety. Railroad managers inspect bridges by measuring displacements under train crossing events to assess their structural condition and prioritize bridge management and safety decisions accordingly. The displacement of a railroad bridge under train crossings is one parameter of interest to railroad bridge owners, as it quantifies a bridge's ability to perform safely and addresses its serviceability. Railroad bridges with poor track conditions will have amplified displacements under heavy loads due to impacts between the wheels and rail joints. Under these circumstances, vehicle-track-bridge interactions could cause excessive bridge displacements, and hence, unsafe train crossings. If displacements during train crossings could be measured objectively, owners could repair or replace less safe bridges first. However, data on bridge displacements is difficult to collect in the field as a fixed point of reference is required for measurement. Accelerations can be used to estimate dynamic displacements, but to date, the pseudo-static displacements cannot be measured using reference-free sensors. This study proposes a method to estimate total transverse displacements of a railroad bridge under live train loads using acceleration and tilt data at the top of the exterior pile bent of a standard timber trestle, where train derailment due to excessive lateral movement is the main concern. Researchers used real bridge transverse displacement data under train traffic from varying bridge serviceability levels. This study explores the design of a new bridge deck-pier experimental model that simulates the vibrations of railroad bridges under traffic using a shake table for the input of train crossing data collected from the field into a laboratory model of a standard timber railroad pile bent. Reference-free sensors measured both the inclination angle and accelerations of the pile cap. Various readings are used to estimate the total displacements of the bridge using data filtering. The estimated displacements are then compared to the true responses of the model measured with displacement sensors. An average peak error of 10% and a root mean square error average of 5% resulted, concluding that this method can cost-effectively measure the total displacement of railroad bridges without a fixed reference.

A Study on the Correlation between Visual Perception Ability and Balance Ability in the Health Elderly (노인의 시지각 능력과 균형능력과의 상관관계에 관한 연구)

  • Jang, Yong-Su;Park, Chang-Sik;Lee, Hyoung-Soo
    • Journal of Korean Physical Therapy Science
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    • v.18 no.2
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    • pp.73-80
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    • 2011
  • Purpose: The purpose of this study was to investigate the correlation between the visual perception ability and the static dynamic balance ability in health elderly. Method: The Motor Free Visual Perception Test-Row Score(MVPT-RS) and MVPT-Process Time(MVPT-PT) were used for evaluating the visual perception abilities. Assessment of the balance ability was taken by using Good Balance System. In the assessment using Good Balance System, X, Y coordinate speed, anterior-posterior direction, medial-lateral direction and Velocity Movement(VM) in standing posture when eye open were measured as static balance abilities. Thirty-seven healthy elderly who live in Gwangyang participated in the experiment for 2 months, from October to November 2010. Results: 1. There were statistically significant differences of MVPT-RS, MVPT-PT, NSB-X, NSB-Y, NSB-VM, OLB-X, and OLB-VM based on the gender(p<0.05). 2. The negative correlations of MVPT-RS:NSB-Y(r=-0.354), MVPT-RS:OLB-X(r=-0.4), MVPT-RS: OLB-Y(r=-0.371), but positive correlations of MVPT-PT:DTB-T showed a statistical significance(r=0.45, p<0.05). 3. The positive correlations of NSB-X:NSB-Y(r=0.54), NSB-X: NSB-VM(r=0.848), NSB-Y:NSB-VM(r=0.531), OLB-X:OLB-Y(r=0.876), OLB-X:OLB-VM(r=0.872), and OLB-Y:OLB-VM(r=0.787) showed statistical significances(p<0.05). Conclusion: These results showed that the visual perception ability was correlated with some balance ability in health elderly. Especially the perception test process time(MVPT-PT) has closely related with the DTB-T. The visual perception ability is considered as a factor on the balance ability in health elderly. Further study will focus on the development of improving program of visual perception ability as an improving method of balancing ability in health elderly.

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The frog appliance for upper molar distalization: a case report (Frog appliance를 이용한 상악 대구치의 원심 이동: 증례 보고)

  • Bayram, Mehmet;Nor, Metin;Kilkis, Dogan
    • The korean journal of orthodontics
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    • v.40 no.1
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    • pp.50-60
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    • 2010
  • The purpose of this article was to evaluate the effects of a new upper molar distalization system, the Frog Appliance, on dentofacial structures in a Class II, division 1 patient. An 11-year-old girl was referred to our clinic for orthodontic treatment. She had a mild skeletal Class II malocclusion with Class II molar and canine relationship on both sides. The treatment plan included distalization of the upper first molars bilaterally followed by full fixed appliance therapy. For the upper molar distalization, a new system, the Frog Appliance, was constructed and applied. Lateral cephalometric radiographs were used to evaluate the treatment results. Distalization of the upper first molars was achieved in four months successfully, and Class I molar relationship was obtained. Total treatment time was 16 months. According to the results of the cephalometric evaluation, a nearly bodily distal molar movement with a slight anchorage loss was attained. In conclusion, the Frog Appliance was found to be a simple, ef ective, non-invasive, and compliance-free intraoral distalization appliance for achieving bilateral molar distalization.

A Study on Reproducibility of Mandibular Movements Using Pantographic Reproducibility Index (PRI) (Pantographic Reproducibility Index(PRI)를 이용한 하악운동의 재현성에 관한 연구)

  • Lee, Sang-Don;Park, Charn-Woon
    • The Journal of Korean Academy of Prosthodontics
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    • v.24 no.1
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    • pp.105-116
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    • 1986
  • In order to determine if a relationship exists between the clinical symptoms of TMJ dysfunction and the reproducibility of mandibular movements, twenty one subjects were chosen. The control group consisted of 5 subjects who were determined to be free from signs and symptoms of dysfunction . The sixteen experimental subjects were selected on the basis of their having dysfunctional symptoms. The author obtained two sets of pantographic tracings. Each set consisted of tracings from three both lateral and one protrusive movements. A second set of tracings were recorded immediately on the new recording papers using the same procedure as the first tracing. The tracings were scored by Pantographic reproducibility index (PRI). The obtained results were as follows. 1. Mean PRI scores of groups increased as the degree of dysfunction were increased. 2. For the groups of no or slight dysfunctional symptoms the PRI scores of the second tracing were smaller than the first one, wherea the scores of the second tracing from $D_2,\;D_3$ group were larger than the first tracing. 3. Differences between the mean PRI scores of control group and those of experimental group were statistically significant. 4. The second sets of tracings were more reliable statistically than those of first ones. 5. PRI can be used as a meaningful aid for the evaluation of the diagnostic and therapeutic results of treatment modalities for the TMJ dysfunction. 6. At 3east two sets of tracings should be recorded when the PRI is to be used to detect the incoordinated movements of TMJ dysfunction patient. 7. PRI scores of control group ($D_0$) was 137.7, thus, mandibular movement was reproducible, whereas PRI scores of experimental groups ($D_1,\;D_2,\;D_3$) were 22.5, 27.7, 30.45 respectively, thus were nonreproducible.

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The Danger-Associated Peptide PEP1 Directs Cellular Reprogramming in the Arabidopsis Root Vascular System

  • Dhar, Souvik;Kim, Hyoujin;Segonzac, Cecile;Lee, Ji-Young
    • Molecules and Cells
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    • v.44 no.11
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    • pp.830-842
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    • 2021
  • When perceiving microbe-associated molecular patterns (MAMPs) or plant-derived damage-associated molecular patterns (DAMPs), plants alter their root growth and development by displaying a reduction in the root length and the formation of root hairs and lateral roots. The exogenous application of a MAMP peptide, flg22, was shown to affect root growth by suppressing meristem activity. In addition to MAMPs, the DAMP peptide PEP1 suppresses root growth while also promoting root hair formation. However, the question of whether and how these elicitor peptides affect the development of the vascular system in the root has not been explored. The cellular receptors of PEP1, PEPR1 and PEPR2 are highly expressed in the root vascular system, while the receptors of flg22 (FLS2) and elf18 (EFR) are not. Consistent with the expression patterns of PEP1 receptors, we found that exogenously applied PEP1 has a strong impact on the division of stele cells, leading to a reduction of these cells. We also observed the alteration in the number and organization of cells that differentiate into xylem vessels. These PEP1-mediated developmental changes appear to be linked to the blockage of symplastic connections triggered by PEP1. PEP1 dramatically disrupts the symplastic movement of free green fluorescence protein (GFP) from phloem sieve elements to neighboring cells in the root meristem, leading to the deposition of a high level of callose between cells. Taken together, our first survey of PEP1-mediated vascular tissue development provides new insights into the PEP1 function as a regulator of cellular reprogramming in the Arabidopsis root vascular system.

Impact of Secondary Currents on Solute Transport in Open-Channel Flows over Smooth-Rough Bed Strips (조(粗)·세립상(細粒床)의 연속구조를 갖는 개수로 흐름에서 오염물질 수송에 대한 이차흐름 영향 분석)

  • Kang, Hyeongsik;Choi, Sung-Uk;Kim, Kyu-Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.1B
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    • pp.73-81
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    • 2009
  • This paper presents a numerical investigation of the impact of the secondary currents on solute transport in open-channel flows. The RANS model with Reynolds stress model is used for flow modeling, and the GGDH(generalized gradient diffusion hypothesis) model is used to close the scalar transport equation. Using the developed model, the impact of secondary currents on solute transport in open channel flows over smooth-rough strip is investigated. Through numerical experiments, the secondary currents are found to affect the solute spreading, leading a movement of the position of the peak concentration and a skewed distribution of solute concentration. Due to the lateral flow of secondary currents near the free surface, the concentration at the rough strip is found to be larger than that at the smooth strip bed. The solute at the rough strip is more rapidly transported than smooth bed. A magnitude analysis of the solute transport rate in scalar transport equation is also carried out to investigate the effect of secondary currents and scalar flux on the concentration distribution.

A Geophysical Study of a Deep sea basin southeast of the Hawaiian Island: Gravity, Magnetic, and Seismic Profiling (Hawaii 동남부 심해저 분지에 대한 지구물리학적 연구 : 중력, 자력 및 탄성파 탐사)

  • 서만철;박찬홍
    • 한국해양학회지
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    • v.26 no.1
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    • pp.1-12
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    • 1991
  • A multi-disciplinary geophysical study including gravity, magnetic, and seismic reflection profiling was carried out in the area between the Clarion fracture zone and the Clippertone fracture zone o the northeastern equatorial Pacific basin. There are small free-air gravity anomalies of less than 20 mgal over seamounts and the east-west trending abyssal hills. The negative residual gravity anomalies over seamounts may indicate the existence of low density seamount roots compared to surrounding oceanic crust. Non-existence of magnetic lineations and the magnetic anomalies of small smplitude with no polarity change in the east-west direction support that the study area belongs to the Cretaceous magnetic quite zone. Positive magnetic anomalies over seamounts offset 100 km in the east-west direction in the southern part of the study area suggest a possibility of left-lateral movement of those seamounts along unknown fractures. The sedimentary section in the study area can be divided into three units (Unit I, unit IIA, and Unit IIB) n the basis of reflection characteristics. the total thickness of sedimentary section varies from 200 to 400 meters and the sedimentary section is thicker in the southern area of rough topography near the seamount belt than in the northern flat area. Manganese nodules are abundant in the southern part of the study area where the ridges are developed and the Unit I layer is thicker than 100 meters.

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