Steel chimneys are used for releasing smoke in various power plants, oil and gas industries. Steel chimneys are generally subjected to static and dynamic loads. Geometry of steel chimney like height, ...diameter at top and bottom plays key role when structure subjected to lateral loading like wind or earthquake. In this study static analysis is conducted on a self-supporting steel chimney of height 90 m subjected to wind load located in Vijayawada for categories 1, 2, 3 and 4. For comparison of IS: 875 (part-3)-1987 to IS: 875 (part-3)-2015, variation of Terrain, height and structure size factor (K2), Design wind speed (VZ), Design wind pressure (PZ), segment moment with respect to chimney base and corresponding segment base of all categories are considered in this study, as basic dimensions of chimney, basic wind speed (Vb), probability factor (K1) and topography factor (K3) are same for both codes. From the study it is found that K2,VZ,PZ, segment moment with respect to chimney base and segment base of all categories are more for IS: 875 (part-3)-2015 than IS: 875 (part-3)-1987. VZ, PZ, segment moment with respect to corresponding segment base of all categories for IS: 875 (part-3)-2015 increases because of Importance factor for cyclonic region (K4).
•Gas conversion is enhanced by addition of calcium manganite to ilmenite.•Online flue gas alkali detection is demonstrated for four biomass fuels.•Oxygen carrier captures over 97% of the incoming ...biomass fuel alkali.•Air reactor flue gas alkali release is similar or greater than in the fuel reactor.
Biomass fuel use in chemical looping combustion enables negative CO2 emissions through BECCS (Bio-Energy Carbon Capture and Storage). Effective biomass utilization in CLC requires an economical and effective oxygen carrier to achieve high fuel conversion, effective CO2 capture, and management of the harmful effects of biomass alkali release (bed agglomeration, oxygen carrier deactivation, fouling and corrosion). These issues were addressed in 100 kW CLC pilot experiments.
Building on previous work, a mixture of a synthetic calcium manganite perovskite and natural ilmenite was used as the oxygen carrier. Four biomass fuels of varied alkali content were tested: black pellets of steam-exploded stem wood (BP), BP impregnated with K2CO3, a mixture of 50% BP with 50% straw pellets, and wood char. Experiments showed high fuel conversion and very high CO2 capture, with overall performance exceeding that of ilmenite and manganese ore. More than 95% gas conversion was achieved with black pellets at around 950 °C.
The fate of biomass alkali, previously virtually unknown in CLC research, was explored by implementing online surface-ionization-based measurement of alkali released in the flue gases of the fuel reactor (FR) and air reactor (AR). Release levels were found to correlate with the fuel alkali content. The flue gas measurements and bed material elemental analyses suggest that most of the fuel alkali are accumulated in the oxygen carrier. Unexpectedly, it was found that flue gas alkali release occurs in both the FR and AR, with AR exhibiting an equal or higher rate of release vs. the FR.
Resumo O artigo apresenta os resultados da leitura, sistematização e análise das atas da Subcomissão da Questão Urbana e de Transporte da Assembleia Nacional Constituinte (1987-1988). A pesquisa ...identificou as instituições que foram chamadas ao debate, o momento em que foram incluídas no debate, e o setor social representado, os profissionais liberais, as empresas estatais, setores ligados ao mercado imobiliário, os intelectuais e os movimentos sociais urbanos. O objetivo da pesquisa foi percorrer o debate em torno da questão urbana na Constituinte de 1987-1988 em busca de explicitar a posição das instituições que foram incluídas no debate. Quais eram as suas propostas? Como o consenso sobre a questão urbana foi construído na Subcomissão? Considerando que esse foi o marco da transição democrática em uma sociedade altamente urbanizada, acreditamos que os elementos dessa investigação possam contribuir ao debate sobre a democracia urbana brasileira e a sua crise institucional no período recente.
Abstract The paper presents the results of reading, systematizing and analyzing the minutes of the Subcommittee on Urban Issues and Transport of the National Constituent Assembly (1987-1988). The research identified the institutions that were called to the debate, the moment when they were included in the debate, and the social sector represented, the professionals, the state companies, sectors linked to the real estate market, the intellectuals and the urban social movements. The objective of the research was to go through the debate around the urban issue in the 1987-1988 Constituent in order to explain the position of the institutions that were included in the debate. What were your proposals? How was the consensus on the urban issue built in the Subcommittee? Considering that this was the landmark of the democratic transition in a highly urbanized society, we believe that the elements of this investigation can contribute to the debate about Brazilian urban democracy and its recently institutional crisis.
This study introduces an attenuation model based on the strain energy approach for estimating earthquake demand energy (EDE) to evaluate soil liquefaction potential. A new method is presented to ...estimate the EDE at a free-field site when only one record of the ground surface acceleration is available. This method was generated after analyzing the earthquake data of 18 downhole arrays in California. The developed method was later employed for calculating the EDE values of 328 earthquake records worldwide. Results showed that several parameters affected the EDE amount, including earthquake magnitude, faulting mechanism, site-to-source distance, shear wave velocity, and peak ground acceleration (PGA). These parameters were categorized by three main functions including source, distance, and site effect functions. An attenuation model was incorporated as a result of these three functions. Finally, the demand energy of two liquefaction array sites-Port Island (PI) site in Japan and Wildlife Liquefaction Array (WLA) site in California-were predicted by the proposed attenuation model and compared to the calculated capacity energies of these sites with satisfactory results.
Abstract
Supernovae (SNe) should both frequently have a binary companion at death and form significant amounts of dust. This implies that any binary companion must lie at the centre of an expanding ...dust cloud and the variable obscuration of the companion as the SN remnant expands will both unambiguously mark the companion and allow the measurement of the dust content through absorption rather than emission for decades after the explosion. However, sufficiently hot and luminous companions can suppress dust formation by rapidly photoionizing the condensible species in the ejecta. This provides a means of reconciling the Type IIb SNe Cas A, which lacks a luminous companion and formed a significant amount of dust (M
d ≳ 0.1 M⊙), with the Type IIb SNe 1993J and 2011dh, both of which appear to have a luminous companion and to have formed a negligible amount of dust (M
d ≲ 10−3 M⊙). The Crab and SN 1987A are consistent with this picture, as both lack a luminous companion and formed significant amounts of dust. An unrecognized dependence of dust formation on the properties of binary companions may help to explain why the evidence for dust formation in SNe appears so contradictory.
This article examines the work of late British photographer Raymond Moore (1920-1987) and the ways in which his images of landscapes and objects allow us to understand his work as being driven ...towards encounters with what I term uncertain places, which is to say places in transition or between states of being that also point the observer of these images to that which lies beyond even photographically-aided perception. This idea is further examined in terms of Moore's acceptance that as a photographer he was but one element in a human-technological process, something that separated his work from the predominant trends in documentary realism that dominated public perceptions of photography during the late period of his career. The uncertain places of Moore's photography, it is argued, matched his temperamental attitude towards his craft and his willingness to allow landscapes and objects, in a sense, to emerge or reveal themselves rather than objectifying or representing them in any conventional sense.
The majority of mitochondrial DNA replication events are terminated prematurely. The nascent DNA remains stably associated with the template, forming a triple-stranded displacement loop (D-loop) ...structure. However, the function of the D-loop region of the mitochondrial genome remains poorly understood. Using a comparative genomics approach we here identify two closely related 15 nt sequence motifs of the D-loop, strongly conserved among vertebrates. One motif is at the D-loop 5'-end and is part of the conserved sequence block 1 (CSB1). The other motif, here denoted coreTAS, is at the D-loop 3'-end. Both these sequences may prevent transcription across the D-loop region, since light and heavy strand transcription is terminated at CSB1 and coreTAS, respectively. Interestingly, the replication of the nascent D-loop strand, occurring in a direction opposite to that of heavy strand transcription, is also terminated at coreTAS, suggesting that coreTAS is involved in termination of both transcription and replication. Finally, we demonstrate that the loading of the helicase TWINKLE at coreTAS is reversible, implying that this site is a crucial component of a switch between D-loop formation and full-length mitochondrial DNA replication.
The 1987 ML 6.3 Edgecumbe earthquake triggered localized liquefaction and associated lateral spreading in the township of Whakatane in the North Island of New Zealand. Subsequent simplified CPT-based ...liquefaction assessments undertaken using modelled Peak Ground Accelerations (PGA) and depth to ground-water for the Edgecumbe earthquake predicts moderate-to-severe liquefaction for much of Whakatane. Variations between the predicted and observed liquefaction severities highlights areas of inconsistent prediction. Potential reasoning for the inconsistencies are subsequently examined through trenching and comparison of CPT traces at selected sites where liquefaction was predicted and was observed during the Edgecumbe earthquake, and sites where liquefaction was predicted yet not observed. Variations in depositional age, stratigraphy including thin-scale interlayering of sands, silts, and pumice, and/or sediment composition are shown to be potential contributing factors. Sites where liquefaction was observed are shown to contain thick potentially liquefiable deposits of recently deposited sand and silt, while sites where liquefaction was predicted yet not observed contain thinner and/or inter-layered liquefiable deposits of older sands and silts. The results highlight the benefit of cross-examining predicted liquefaction severities with historical case histories and outline local site conditions that may result in inconsistent liquefaction assessments.
•Predicted liquefaction manifestation are cross-examined using post-event observations.•Liquefaction is adequately predicted proximal to river banks and in thick deposits of low-density fine sands to silts.•Manifestation severity may be over-predicted in distal floodplains and/or thinly inter-layered deposits containing pumice•Trenching enables ground-truthing which may improve interpretations soil types and liquefaction triggering.
Residents of dwellings near railway tunnels may be exposed to noise, which propagates through the tunnel and ground and into the home. Noise radiated into bedrooms may disrupt sleep, which can have ...negative consequences for physical and mental wellbeing. In this paper, we present a laboratory investigation of the impact of ground-borne railway noise on physiologic and self-reported sleep. Over five consecutive nights, including habituation and control nights, 23 healthy participants were exposed to noise of two different frequency spectra at maximum levels of 35, 40 and 45 dB. Sleep was measured using polysomnography and questionnaires. Heart rate was measured using electrocardiography. Sleep was significantly disturbed, both in terms of physiologic and self-reported measures, during nights with 45 dB noise, although the number and size of effects was modest. No significant differences in overall sleep structure or subjective sleep disturbance and quality were found between control and 35 dB nights. Within 60 s following noise onset, the noise spectrum with higher amplitude frequencies above 100 Hz led to increases in heart rate at noise levels of 35 dB and above, and increased arousal probability at a noise level of 45 dB. The results generally support that the proposed Swedish guideline value of 35 dB maximum noise level indoors may be suitable for protecting against adverse sleep outcomes due to ground-borne railway noise.
•Physiologic sleep disruption by ground-borne railway noise increased with noise level.•Majority of self-reported sleep measures were worse after 45 dB nights than baseline.•Noise spectra dominated by very low frequencies had no effect on physiologic response.
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