<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3ASfrwbfrg" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>Bi-Directional Dynamic Vibration Absorber for Small-Radius Curved Track Systems: Design and Performance Evaluation</title><link>http://pubsindex.trb.org/view/2647069</link><description><![CDATA[Low-frequency vibration amplification in steel-spring floating slab track is especially significant in small-radius curves. To mitigate this issue, a novel bi-directional dynamic vibration absorber (Bi-DVA) is proposed to effectively suppress such vibrations and improve the stability of the track system. A coupled dynamic model, which integrates the vehicle, curved track segment, floating slab, and Bi-DVA, was developed using extended fixed-point theory, vehicle-track coupled dynamics theory, and finite element analysis. The optimal configuration of the Bi-DVA’s parameters was thoroughly explored, and its performance under various operational conditions was assessed in terms of vibration reduction and enhancement of wheel-rail safety metrics. The vertical and lateral vibration amplitudes of the floating slab were reduced by up to 10.2 dB and 8.9 dB. The vertical and lateral accelerations of the rail were decreased by 11.7 m/s2 and 1.82 m/s2, and the peak vertical and lateral accelerations of the vehicle body dropped by 0.44 m/s2 and 0.19 m/s2, respectively. Additionally, the derailment coefficient was reduced by 0.08, and the wheel load reduction rate decreased by 0.06.]]></description><pubDate>Fri, 09 Jan 2026 16:59:37 GMT</pubDate><guid>http://pubsindex.trb.org/view/2647069</guid></item><item><title>A Novel Renewable Low-Frequency Acoustic Energy Harvesting Noise Barrier for China High-Speed Railway</title><link>http://pubsindex.trb.org/view/1495462</link><description><![CDATA[With the rapid development of high-speed rail transportation in China, the problem of noise pollution has required greater attention. The noise is also a kind of renewable energy that can be collected to generate electricity. Noise reduction performance of existing noise barriers needs to be improved due to multiple reflections of low frequency sound waves between the running high-speed trains and the sound barrier, which means a waste of sound energy. In this paper, the authors present a novel acoustic energy harvesting noise barrier (AEHNB) using Helmholtz resonator and PVDF film to convert acoustic energy of the noise from running high-speed trains to electricity. Purposes of noise reduction and electricity generation are achieved at the same time. The generated electricity is stored in the super capacitor to be standby power supplies for rail-side equipment, such as the railway crossing alarms, sensors and monitors. The renewable energy application scheme consists of four main components: the noise collection input module, sound pressure amplification module, electricity generator module and power storage module. The theoretical data shows that AEHNB can achieve 8-10% reduction of high-speed rail noise and one-year power generation of 2628.02kWh, which will reduce the cost of electricity by 315.36 dollars every year.]]></description><pubDate>Wed, 24 Jan 2018 09:24:04 GMT</pubDate><guid>http://pubsindex.trb.org/view/1495462</guid></item><item><title>Low Frequency Vibration from Light Rail Vehicles</title><link>http://pubsindex.trb.org/view/1437273</link><description><![CDATA[The question of how much low-frequency vibration is generated by operations of typical light rail vehicles is an important issue when a proposed light rail system will be in close proximity to vibration sensitive research facilities. In this paper the authors define low-frequency vibration to be vibration radiated at frequencies below 25 Hz because rail transit vibration often is lower than the vibration from buses and trucks at frequencies below 25 Hz. This paper is largely based on vibration measurements vibration performed in support of the vibration monitoring system that was installed in the University-Link extension of the Seattle Link LRT system. The monitoring system is designed to protect vibration sensitive research facilities that are relatively close to the subway. The testing has shown that there is substantial low-frequency vibration at the vibration monitors from traffic on nearby roadways and that this vibration is often greater than the vibration generated by train operations. In other words, at low frequencies, the vibration from trains passing about 10 ft from the monitors is often less than the vibration created by traffic that is at least 200 ft from the monitors. This is a non-intuitive result, and the primary purpose of this paper is to examine possible reasons for this result and what factors contribute to the low-frequency traffic vibration being greater than the low-frequency train vibration. The results of this analysis are applicable to other rail transit projects where low frequency vibration interfering with research equipment is a concern.]]></description><pubDate>Tue, 24 Jan 2017 15:32:18 GMT</pubDate><guid>http://pubsindex.trb.org/view/1437273</guid></item><item><title>Weight-Based Shortest-Path Aided Map-Matching Algorithm for Low-Frequency Positioning Data</title><link>http://pubsindex.trb.org/view/1092603</link><description><![CDATA[Existing map-matching algorithms that utilize road segment connectivity along with other data (i.e. position, speed and heading) are primarily suitable for high frequency (1Hz or higher) positioning data. While applying these algorithms to low frequency data such as data from a fleet of buses or light duty vehicles, the performance of these algorithms reduces significantly in terms of correct link identification. Such a performance may not be suitable for some real-time Intelligent Transport System (ITS) applications such as estimating link travel time from low frequency GPS data. Therefore, this paper develops a weight-based shortest path aided map-matching (spMM) algorithm that enhances the map-matching process of low frequency data. The well-known A* search algorithm is employed to derive the shortest path between two consecutive fixes while considering link connectivity and turn restriction at junctions. In the developed spMM algorithm, two additional weights related to the shortest path along with the two weights (i.e. proximity and bearing difference) commonly used in existing map-matching algorithms are employed. One additional weight is related to the distance along the shortest path and the distance along the vehicle trajectory. The other additional weight is associated with the heading information derived from the shortest path and the vehicle trajectory.  The developed spMM algorithm has been tested using a series of real-world dataset of varying frequencies (i.e. 1Hz, 0.2Hz, 0.033Hz and 0.0167Hz).  A high accuracy integrated navigation system (a high-grade INS and a carrier-phase GPS receiver) has used to measure the performance of the developed algorithm. The results suggest that the spMM algorithm identifies 97.5% of the links correctly for all frequencies. Without the information from the shortest path, the performance of the algorithm reduces to in the region of 70% in terms of correct link identification. The results also suggest that the algorithm is suitable for real-time applications.]]></description><pubDate>Wed, 20 Apr 2011 14:03:05 GMT</pubDate><guid>http://pubsindex.trb.org/view/1092603</guid></item><item><title>Low-Frequency Noise Effects in Residential Buildings Along a Bus Rapid Transit (BRT) Route</title><link>http://pubsindex.trb.org/view/813733</link><description><![CDATA[This paper summarizes an investigation of low-frequency noise effects that was conducted in residential buildings along the Sliver Line Bus Rapid Transit (BRT) route in Boston, MA. Soon after a new fleet of Neoplan buses began operating on the line, the Massachusetts Bay Transportation Authority (MBTA) received complaints about rumbling noise and vibration from residents who live along the route. The complaints were primarily related to noise and vibration that occurred inside homes when the buses were idling at stops along the line. The Neoplan bus that operates on the Silver Line is an 18.3 m (60 ft) long, articulated, low-floor unit that runs on compressed natural gas (CNG). The bus is powered by a six cylinder, 4-cycle engine that idles at a rotation speed of 700 rpm. In response to the community complaints, an investigation was undertaken to diagnose the problem and develop noise control solutions. Initially, noise and vibration measurements were conducted at affected residences to document the problem, and field tests of a representative bus were performed for diagnostic purposes. Based on the outcome of the initial tests, modifications were made to one of the buses and additional tests were performed. The interim results of this investigation are described below.]]></description><pubDate>Fri, 27 Jul 2007 07:06:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/813733</guid></item><item><title>ASSESSMENT OF INTERACTION BETWEEN ROAD ROUGHNESS AND HEAVY VEHICLES</title><link>http://pubsindex.trb.org/view/645255</link><description><![CDATA[Road surface roughness excites low- and high-frequency vibration modes of a heavy articulated vehicle body.  These vibrations result in motions in all directions that detract from the driver's perceived ride and comfort and increase pavement damage due to dynamic wheel loads (DWLs).  A subjective assessment survey was conducted to identify surface roughness characteristics that mainly influence the perceptions of heavy-vehicle drivers of pavement rideability and their comfort. The latter was achieved by correlating drivers' ratings to roughness contents in different roughness wavebands.  The results indicated that the drivers mainly object to low-frequency body vibrations excited by roughness wavelengths in the range of 4.88 to 19.5 m.  Roughness content in this band was used to establish a new profile-based index called the profile index for truck (PIt).  Drivers consider pavement rideability to be poor when PIt exceeds 2.75 m/km.  PIt provides better predictions of heavy vehicle ride than the international roughness index (IRI).  The methodology for developing the PIt and assessment of its reliability as a measure of heavy vehicle ride are described. The latter was achieved by testing the statistical significance of the effects of factors other than road roughness that influence the perceived ride of truck drivers.  They include factors related to the vehicle, the road, and the driver as well as situational factors.  In addition, PIt was found to be a better indicator than IRI of the levels of whole body vibrations transmitted to the driver through the seat and a better predictor of the magnitude of DWL to which the test pavements are subject.]]></description><pubDate>Wed, 14 May 2003 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/645255</guid></item><item><title>FIELD IMPLEMENTATION OF TUNED MASS DAMPERS FOR SUPPRESSION OF STAY CABLE VIBRATION</title><link>http://pubsindex.trb.org/view/734676</link><description><![CDATA[This Innovations Deserving Exploratory Analysis (IDEA) project is a follow-on activity for an earlier IDEA project (NCHRP-50) to demonstrate the effectiveness of tuned mass dampers (TMDs) in minimizing stay cable vibrations in a full-scale field trial on an actual highway bridge.  Several visco-elastic materials and model configurations were investigated to identify models that could be considered for full-scale prototype adaptation. Simultaneous to experimenting with various models, analytical investigations were conducted to calculate required properties and dimensions of the full-scale versions of the models.  The analytical evaluation identified a problem in adapting the scaled models to full-scale sizes due to low frequency vibrations of the actual bridge stay cables.  This problem was addressed by using a hybrid of impact and tuned damper. Laboratory tests, conducted on model cables using two types of tuned impact dampers (TIDs), showed the TID to be more effective than the TMD.  The TID was also found to be effective at low frequencies.  Using the evaluation results, a full-scale refined TID system was designed and fabricated.  The prototype system was installed on experimental basis on the Talmadge Bridge in Savannah, Georgia.  The field test results so far confirm the efficiency and applicability of the TID system for increasing the cable apparent damping ratios and suppression of excessive vibrations.]]></description><pubDate>Tue, 04 Mar 2003 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/734676</guid></item><item><title>STABILIZATION OF WEAK CLAY WITH STRONG SAND AND GEOGRID AT SAND-CLAY INTERFACE</title><link>http://pubsindex.trb.org/view/540280</link><description><![CDATA[The load-bearing capacity of a weak clay subgrade can be increased by placing a strong granular base course of limited thickness on top of the clay layer.  The load-bearing capacity can be increased further, or the thickness of the granular base course can be reduced, by separating both layers by a geogrid. Laboratory model test results for the ultimate bearing capacity of a rigid strip loading on the surface of a granular soil underlain by a soft clay with a layer of geogrid at the interface of the two soils are presented.   The optimum thickness of the granular soil layer and the critical width of the geogrid layer required to derive the maximum benefit from the reinforcement were determined.  Model test results on the permanent settlement of the rigid strip load caused by cyclic loading of low frequency are presented.]]></description><pubDate>Wed, 28 Oct 1998 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/540280</guid></item><item><title>CHARACTERIZATION OF GRANULAR SYSTEMS BY DIGITAL SIGNAL PROCESSING OF LOW STRAIN WAVE RESPONSE</title><link>http://pubsindex.trb.org/view/470053</link><description><![CDATA[The characterization and quality assessment of composite materials, particularly those constructed of residual materials such as slags, ashes, and crumb rubber, are difficult because of chemical and physical inhomogeneity and inconsistency at the time of their production.  The characterization of granular systems, constructed of a mixture of geological and residual materials, may provide inconclusive information when tested by existing methods.  The proposed nondestructive evaluation uses low-strain, low-frequency dynamic excitation as a means to better evaluate such materials.  The applied excitation results in a sample response characterized by wave patterns.  The wave pattern response is analyzed by digital signal processing and an artificial neural network (ANN) system to facilitate characterization of the material.  Dynamic excitation of representative samples was accomplished using a longitudinal-torsional resonant column.  Nondestructive testing was conducted at low strain levels applying a torsional oscillatory motion.  The resulting sample response wave forms were recorded.  The shear modulus values obtained at the resonant frequency of each sample were used to train an ANN system to characterize sample wave responses measured at random frequencies.  The recorded sample response wave forms were analyzed to identify the embedded dominant frequencies, which were unique signatures of the tested materials.  These signatures were then submitted to the previously trained ANN to predict the material shear modulus.  The samples tested were composed of dry Ottawa sand (0.85 to 0.6 mm), Ottawa sand and crumb rubber modifier, and soda-lime spheres compacted at various densities and tested under different confining pressures.  Distinctive patterns, unique to the granular sample composition, were obtained.  These are termed the signature patterns.  A fast Fourier transform algorithm was used to convert collected data to the frequency domain.  ANN analysis was applied to enhance pattern recognition and characterize the samples according to their shear moduli.]]></description><pubDate>Mon, 03 Feb 1997 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/470053</guid></item><item><title>LA GUARDIA AIRPORT GROUND-NOISE ABATEMENT STUDY</title><link>http://pubsindex.trb.org/view/415039</link><description><![CDATA[An airport ground-noise abatement study was conducted for the Port Authority of New York and New Jersey along the western boundary of New York City's La Guardia Airport between 1986 and 1988.  The investigation included measurements to characterize multiple noise sources, analysis of noise abatement options, and postconstruction measurements.  The noise barrier design was conducted by using one-third-octave band analysis to predict expected loss of excess ground attenuation, barrier insertion loss, and net noise reduction.  The study used the DIFRCT model developed by Embleton, Piercy, and Isei to calculate noise barrier insertion losses in the presence of ground effects. Although an example of one particular application and not a thorough review of the model is provided, the following conclusions were noted.  The modified DIFRCT model was useful in predicting the ground effect owing to soft ground, especially at lower frequencies.  In addition the study indicated that the model may be limited in its applications to hard-ground situations because of lack of coherent long-distance propagation at higher frequencies.]]></description><pubDate>Tue, 31 Jan 1995 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/415039</guid></item><item><title>LOW-FREQUENCY VIBROPILE DRIVING AND PREDICTION OF DYNAMIC TIP RESISTANCE OF PILES</title><link>http://pubsindex.trb.org/view/365963</link><description><![CDATA[Experimental tests have been conducted on mainly open-ended pile models driven into fine-grained sand (soil) by low-frequency vibratory excitations.  The minimum input force amplitude that causes a pile to penetrate the soil and the optimum amplitude that ensures the quickest penetration of the pile to the ultimate depth have been determined. Postoptimum force levels have been found to induce a high impactive reaction at the pile tip (i.e., dynamic tip resistance), and this phenomenon has been investigated.  A mathematical theory to predict the dynamic tip resistance is proposed.  Piles with various tip configurations have been tested.]]></description><pubDate>Sun, 31 May 1992 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/365963</guid></item><item><title>A PREDICTION PROCEDURE FOR RAIL TRANSPORTATION GROUNDBORNE NOISE AND VIBRATION</title><link>http://pubsindex.trb.org/view/282889</link><description><![CDATA[A procedure has been developed for predicting groundborne noise and vibration caused by rail transportation systems. The primary focus is the estimation of low-level, low-frequency groundborne noise and vibration between 6.3 and 200 Hz in residential and commercial buildings near at-grade and subway track.  Two particular features of the method are the use of impact-testing procedures to characterize vibration propagation in soils and the use of 1/3 octave band force densities to represent specific vehicle and track systems.  Directions for future research are discussed, including numerical modeling of subway structures and vibration propagation in soils, truck and track dynamics, and propagation of vibration through buildings.]]></description><pubDate>Sun, 31 Jul 1988 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/282889</guid></item></channel></rss>