Projeto de experimentos em rodas ferroviárias fundidas em aço, com o uso da técnica de Taguchi

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Service condition of railroad corridors around the insulated rail joints

Railroad corridors contain large number of Insulated Rail Joints (IRJs) that act as safety critical elements in the circuitries of the signaling and broken rail identification systems. IRJs are regarded as sources of excitation for the passage of loaded wheels leading to high impact forces; these forces in turn cause dips, cross levels and twists to the railroad geometry in close proximity to the sections containing the IRJs in addition to the local damages to the railhead of the IRJs. Therefore, a systematic monitoring of the IRJs in railroad is prudent to mitigate potential risk of their sudden failure (e.g., broken tie plates) under the traffic. This paper presents a simple method of periodic recording of images using time-lapse photography and total station surveying measurements to understand the ongoing deterioration of the IRJs and their surroundings. Over a 500 day period, data were collected to examine the trends in narrowing of the joint gap due to plastic deformation the railhead edges and the dips, cross levels and twists caused to the railroad geometry due to the settlement of ties (sleepers) around the IRJs. The results reflect that the average progressive settlement beneath the IRJs is larger than that under the continuously welded rail, which leads to excessive deviation of railroad profile, cross levels and twists.

Measurement, Simulation, and Analysis of the Mechanical Response of Railroad Track

Increased railroad traffic volumes, speeds, and axle loads have created a need to better measure track quality. Previous research has indicated that the vertical track deflection provides a meaningful indicator of track integrity. The measured deflection can be related to the bending stresses in the rail as well as characterize the mechanical response of the track. This investigation summarizes the simulation, analysis and development of a measurement system at the University of Nebraska (UNL) to measure vertical track deflection in real-time from a car moving at revenue speeds. The UNL system operates continuously over long distances and in revenue service. Using a camera and two line lasers, the system establishes three points of the rail shape beneath the loaded wheels and over a distance of 10 ft. The resulting rail shape can then be related to the actual bending stress in the rail and estimate the track support through beam theory. Finite element simulations are used to characterize the track response as related to the UNL measurement system. The results of field tests using bondable resistance strain gages illustrate the system’s capability of approximating the actual rail bending stresses under load.

Bayesian methodology incorporating expert judgment for ranking countermeasure effectiveness under uncertainty: Example applied to at grade railroad crossings in Korea

This paper describes the formalization and application of a methodology to evaluate the safety benefit of countermeasures in the face of uncertainty. To illustrate the methodology, 18 countermeasures for improving safety of at grade railroad crossings (AGRXs) in the Republic of Korea are considered. Akin to “stated preference” methods in travel survey research, the methodology applies random selection and laws of large numbers to derive accident modification factor (AMF) densities from expert opinions. In a full Bayesian analysis framework, the collective opinions in the form of AMF densities (data likelihood) are combined with prior knowledge (AMF density priors) for the 18 countermeasures to obtain ‘best’ estimates of AMFs (AMF posterior credible intervals). The countermeasures are then compared and recommended based on the largest safety returns with minimum risk (uncertainty). To the author's knowledge the complete methodology is new and has not previously been applied or reported in the literature. The results demonstrate that the methodology is able to discern anticipated safety benefit differences across candidate countermeasures. For the 18 at grade railroad crossings considered in this analysis, it was found that the top three performing countermeasures for reducing crashes are in-vehicle warning systems, obstacle detection systems, and constant warning time systems.

Greener and leaner : unleashing capacity of railroad concrete ties via limit states concept

New knowledge has raised a concern about the cost-ineffective design methods and the true performance of railroad prestressed concrete ties. Because of previous knowledge deficiencies, railway civil and track engineers have been aware of the conservative design methods for structural components in any railway track that rely on allowable stresses and material strength reductions. In particular, railway sleeper (or railroad tie) is an important component of railway tracks and is commonly made of prestressed concrete. The existing code for designing such components makes use of the permissible stress design concept, whereas the fiber stresses over cross sections at initial and final stages are limited by some empirical values. It is believed that the concrete ties complying with the permissible stress concept possess unduly untapped fracture toughness, based on a number of proven experiments and field data. Collaborative research run by the Australian Cooperative Research Centre for Railway Engineering and Technologies (Rail CRC) was initiated to ascertain the reserved capacity of Australian railway prestressed concrete ties that were designed using the existing design code. The findings have led to the development of a new limit-states design concept. This paper highlights the conventional and the new limit-states design philosophies and their implication to both the railway community and the public. © 2011 American Society of Civil Engineers.

Destroyed Railroad Wagon in Mero Laburcz Military; World War I

Bernhard Bardach World War I Album I

Model exact low-lying states and spin dynamics in ferric wheels: Fe-6 to Fe-12

Using an efficient numerical scheme that exploits spatial symmetries and spin parity, we have obtained the exact low-lying eigenstates of exchange Hamiltonians for ferric wheels up to Fe-12. The largest calculation involves the Fe-12 ring which spans a Hilbert space dimension of about 145x10(6) for the M-S=0 subspace. Our calculated gaps from the singlet ground state to the excited triplet state agree well with the experimentally measured values. Study of the static structure factor shows that the ground state is spontaneously dimerized for ferric wheels. The spin states of ferric wheels can be viewed as quantized states of a rigid rotor with the gap between the ground and first excited states defining the inverse of the moment of inertia. We have studied the quantum dynamics of Fe-10 as a representative of ferric wheels. We use the low-lying states of Fe-10 to solve exactly the time-dependent Schrodinger equation and find the magnetization of the molecule in the presence of an alternating magnetic field at zero temperature. We observe a nontrivial oscillation of the magnetization which is dependent on the amplitude of the ac field. We have also studied the torque response of Fe-12 as a function of a magnetic field, which clearly shows spin-state crossover.

Rollover-Preventive Force Synthesis at Active Suspensions in a Vehicle Performing a Severe Maneuver With Wheels Lifted Off

Among the intelligent safety technologies for road vehicles, active suspensions controlled by embedded computing elements for preventing rollover have received a lot of attention. The existing models for synthesizing and allocating forces in such suspensions are conservatively based on the constraints that are valid until no wheels lift off the ground. However, the fault tolerance of the rollover-preventive systems can be enhanced if the smart/active suspensions can intervene in the more severe situation in which the wheels have just lifted off the ground. The difficulty in computing control in the last situation is that the vehicle dynamics then passes into the regime that yields a model involving disjunctive constraints on the dynamics. Simulation of dynamics with disjunctive constraints in this context becomes necessary to estimate, synthesize, and allocate the intended hardware realizable forces in an active suspension. In this paper, we give an algorithm for the previously mentioned problem by solving it as a disjunctive dynamic optimization problem. Based on this, we synthesize and allocate the roll-stabilizing time-dependent active suspension forces in terms of sensor output data. We show that the forces obtained from disjunctive dynamics are comparable with existing force allocations and, hence, are possibly realizable in the existing hardware framework toward enhancing the safety and fault tolerance.

Life-cycle analysis of energy and greenhouse gas emissions of automotive fuels in India: Part 2-Well-to-wheels analysis

In this second of the two-part study, the results of the Tank-to-Wheels study reported in the first part are combined with Well-to-Tank results in this paper to provide a comprehensive Well-to-Wheels energy consumption and greenhouse gas emissions evaluation of automotive fuels in India. The results indicate that liquid fuels derived from petroleum have Well-to-Tank efficiencies in the range of 75-85% with liquefied petroleum gas being the most efficient fuel in the Well-to-Tank stage with 85% efficiency. Electricity has the lowest efficiency of 20% which is mainly attributed due to its dependence on coal and 25.4% losses during transmission and distribution. The complete Well-to-Wheels results show diesel vehicles to be the most efficient among all configurations, specifically the diesel-powered split hybrid electric vehicle. Hydrogen engine configurations are the least efficient due to low efficiency of production of hydrogen from natural gas. Hybridizing electric vehicles reduces the Well-to-Wheels greenhouse gas emissions substantially with split hybrid configuration being the most efficient. Electric vehicles do not offer any significant improvement over gasoline-powered configurations; however a shift towards renewable sources for power generation and reduction in losses during transmission and distribution can make it a feasible option in the future. (C) 2015 Elsevier Ltd. All rights reserved.

Panama Railroad Station, Balboa, Canal Zone - Old Timers arriving Jan. 18, 1928

Leonard Carpenter Panama Canal Collection. Photographs: Views of Panama and the Canal. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.