EFFECTS OF RAILROAD TRACK STRUCTURAL COMPONENTS AND SUBGRADE ON DAMPING AND DISSIPATION OF TRAIN INDUCED VIBRATION

A method for numerical simulation of train induced track vibration and wave propagation in subgrade has been proposed. The method uses a mass to simulate the bogie of a train and considers the effect of rail roughness. For this method, rail roughness is considered as a randomly generated signal and a filter is used to block the undesired components. The method predicts the particle velocity around the track and can be applied to many kinds of railroad trackbeds including traditional ballast trackbed and modern Hot mix asphalt (HMA) trackbed. Results from ballast and HMA trackbeds are compared and effects of HMA layer on damping track vibration and dissipating wave propagation are presented. To verify the credibility of the method, in-track measurements were also conducted. Site measurements included performing geophysical tests such as spectral analysis of surface wave test and seismic refraction test to determine the subsurface conditions at the test site. Ballast and HMA samples were tested in the laboratory by resonant column test to obtain the material properties. Particle velocities were measured and analyzed in the frequency domain. Results from in-track tests confirm the applicability of the numerical method. The findings and conclusions are summarized and future research topics are suggested

(Z)-1-Phenyl-3-(3-pyridyl­meth­ylamino)­but-2-en-1-one

The reaction of 3-C5H4NCH2NH2 and C6H5COCH2COCH3 affords the title compound, C16H16N2O. The O=C—C=C—N portion is essentially planar [maximum deviation = 0.046 (2) Å] and is aligned at dihedral angles of 22.6 (1) and 78.9 (1)° to the phenyl and pyridyl rings, respectively. The N—H and O=C groups are linked by an intra­molecular hydrogen bond. In the crystal, C—H⋯O hydrogen bonds and C—H⋯π inter­actions occur

Geoengineered ocean vertical water exchange can accelerate global deoxygenation

Ocean deoxygenation is a threat to marine ecosystems. We evaluated the potential of two ocean intervention technologies, i.e. “artificial downwelling (AD)” and “artificial upwelling (AU)”, for remedying the expansion of Oxygen Deficient Zones (ODZs). The model‐based assessment simulated AD and AU implementations for 80 years along the eastern Pacific ODZ. When AD was simulated by pumping surface seawater to the 178 ~ 457 m depth range of the ODZ, vertically integrated oxygen increased by up to 4.5% in the deployment region. Pumping water from 457 m depth to the surface (i.e. AU), where it can equilibrate with the atmosphere, increased the vertically integrated oxygen by 1.03%. However, both simulated AD and AU increased biological production via enhanced nutrient supply to the sea surface, resulting in enhanced export production and subsequent aerobic remineralization also outside of the actual implementation region, and an ultimate net decline of global oceanic oxygen

Model-based investigation of nitrogen and oxygen cycles in the oxygen minimum zone of the eastern tropical South Pacific

The nitrogen and oxygen cycles of the eastern tropical South Pacific (ETSP) are investigated with a box and a high-resolution 3D model. The reduced remineralization rate under anoxic conditions slower than that via aerobic respiration can prevent nitrate depletion in the oxygen minimum zone. The local response of ETSP to nitrogen deposition and benthic remineralization indicates a stabilizing feedback. In the high-resolution 3D model, oxygen supply from the southern subtropical ocean into ETSP mainly impacts the deep ocean

What prevents nitrogen depletion in the oxygen minimum zone of the eastern tropical South Pacific?

Local coupling between nitrogen fixation and denitrification in current biogeochemical models could result in runaway feedback in open-ocean oxygen minimum zones (OMZs), eventually stripping OMZ waters of all fixed nitrogen. This feedback does not seem to operate at full strength in the ocean, as nitrate does not generally become depleted in open-ocean OMZs. To explore in detail the possible mechanisms that prevent nitrogen depletion in the OMZ of the eastern tropical South Pacific (ETSP), we develop a box model with fully prognostic cycles of carbon, nutrients and oxygen in the upwelling region and its adjacent open ocean. Ocean circulation is calibrated with Δ14C data of the ETSP. The sensitivity of the simulated nitrogen cycle to nutrient and oxygen exchange and ventilation from outside the model domain and to remineralization scales inside an OMZ is analysed. For the entire range of model configurations explored, we find that the fixed-N inventory can be stabilized at non-zero levels in the ETSP OMZ only if the remineralization rate via denitrification is slower than that via aerobic respiration. In our optimum model configuration, lateral oxygen supply into the model domain is required at rates sufficient to oxidize at least about one fifth of the export production in the model domain to prevent anoxia in the deep ocean. Under these conditions, our model is in line with the view of phosphate as the ultimate limiting nutrient for phytoplankton, and implies that for the current notion of nitrogen fixation being favoured in N-deficit waters, the water column of the ETSP could even be a small net source of nitrate

Effect of High In-Situ Stress on Braced Excavations

The two underground stations and portals of Metro Gold Line\u27s East Los Angeles extension were excavated in heavily over-consolidated alluvium. The excavations were supported with heavy soldier piles with pre-loaded steel-pipe struts. When measured strut loads increased to up to 3 times the design value, and strut-waler connections began to buckle, the contractor was directed to install additional struts. Maintaining that the problem had been caused by inadequate construction means and methods, the owner denied a change-order request for this work. This paper describes the contractor’s investigation into the cause of strut overloading in preparation for a formal hearing by a Dispute Resolution Board. The study concluded that the extremely high bracing loads were caused by high in-situ stresses in the region, which had not been accounted for in the shoring-pressure diagrams provided in the contract drawings

Rapid Remission in Peripheral T-Cell Lymphoma of the Nasal Type by the Bortezomib plus CHOP Therapy

Peripheral T-cell lymphoma (PTCL) is rare and difficult to treat for its high relapse rate. The authors report a case of PTCL of the skin, regarding which clinical and pathological features, treatment, and prognosis were discussed. A 66-year-old woman was admitted with complaints of enlarging erythematous noduloplaques on the right anterior tibial skin for one year and similar lesions on the left for 6 months. Surgical resection of right leg lesion and biopsy of enlarged inguinal lymph nodes histologically indicated a PTCL of the nasal type. The patient was treated by CHOP plus bortezomib, reached complete remission just after two courses of chemotherapy and then received another two as consolidation. The patient remained in remission for 11 months until local relapse. As for cutaneous lesions, detailed lymph node examination and prompt tissue biopsy are judicious choices prior to any medical management. The chemotherapy consisting of bortezomib and CHOP is safe and efficient in PTCL of the skin

Seismic Performance Evaluation of a Submarine Gas Pipeline

Analyses were conducted on the seismic performance of a proposed offshore gas flowline, which connects a manifold in 830-m water depth to a riser platform in shallow waters of the outer continental shelf. Climbing a 10-degree continental slope, the flowline will be installed on the seafloor underlain by deep carbonate sediments of sands and silty clays. Two types of analyses were performed for a critical segment of the flowline, where it traverses a narrow ridge flanked by two deep submarine canyons: (1) probabilistic analyses using simplified empirical methods; and (2) deterministic 2D and 3D analyses with FLAC using a nonlinear, effective-stress soil model fully coupled with an empirical pore-pressure generation scheme. Soil properties were derived from PCPT and T-bar data, Bender element tests, and monotonic and cyclic direct simple shear tests. The analysis results indicated an extremely small likelihood of liquefaction along the flowline, with only small deformations predicted to occur for ground motions with a return period of 5,000 years

Box-modeling of the impacts of atmospheric nitrogen deposition and benthic remineralization on the nitrogen cycle of the eastern tropical South Pacific

Both atmospheric deposition and benthic remineralisation influence the marine nitrogen cycle, and hence ultimately also marine primary production. The biological and biogeochemical relations in the eastern tropical South Pacific (ETSP) among nitrogen deposition, benthic denitrification and phosphorus regeneration are analysed in a prognostic box model of the oxygen, nitrogen and phosphorus cycles in the ETSP. Atmospheric nitrogen deposition ( ≈ 1.5 Tg N yr−1 for the years 2000–2009) is offset by half in the model by reduced N2 fixation, with the other half transported out of the model domain. Model- and data-based benthic denitrification in our model domain are responsible for losses of 0.19 and 1.0 Tg Tg N yr−1, respectively, and both trigger nitrogen fixation, partly compensating for the NO3− loss. Model- and data-based estimates of enhanced phosphate release via sedimentary phosphorus regeneration under suboxic conditions are 0.062 and 0.11 Tg N yr−1, respectively. Since phosphate is the ultimate limiting nutrient in the model, even very small additional phosphate inputs stimulate primary production and subsequent export production and NO3− loss in the oxygen minimum zone (OMZ). A sensitivity analysis of the local response to both atmospheric deposition and benthic remineralisation indicates dominant stabilising feedbacks in the ETSP, which tend to keep a balanced nitrogen inventory; i.e. nitrogen input by atmospheric deposition is counteracted by decreasing nitrogen fixation; NO3− loss via benthic denitrification is partly compensated for by increased nitrogen fixation; enhanced nitrogen fixation stimulated by phosphate regeneration is partly counteracted by stronger water-column denitrification. Even though the water column in our model domain acts as a NO3− source, the ETSP including benthic denitrification might be a NO3− sink