Traffic recovery time estimation under different flow regimes in traffic simulation

AbstractIncident occurrence and recovery are critical to the smooth and efficient operations of freeways. Although many studies have been performed on incident detection, clearance, and management, travelers and traffic managers are unable to accurately predict the length of time required for full traffic recovery after an incident occurs. This is because there are no practical studies available to estimate post-incident recovery time. This paper estimates post-incident traffic recovery time along an urban freeway using traffic simulation and compares the simulation results with shockwave theory calculations. The simulation model is calibrated and validated using a freeway segment in Baltimore, MD. The model explores different flow regimes (traffic intensity) and incident duration for different incident severity, and their effects on recovery time. A total of 726 simulations are completed using VISSIM software. Finally, the impact of congestion and incident delay on the highway network is quantified by a regression formula to predict traffic recovery time. The developed regression model predicts post-incident traffic recovery time based on traffic intensity, incident duration, and incident severity (ratio of lanes closure). In addition, three regression models are developed for different flow regimes of near-capacity, moderate, and low-traffic intensity. The model is validated by collected field data on two different urban freeways

A Study on the liquefaction risk in seismic design of foundations

A fully coupled non-linear effective stress response finite difference (FD) model is built to survey the counter-intuitive recent findings on the reliance of pore water pressure ratio on foundation contact pressure. Two alternative design scenarios for a benchmark problem are explored and contrasted in the light of construction emission rates using the EFFC-DFI methodology. A strain-hardening effective stress plasticity model is adopted to simulate the dynamic loading. A combination of input motions, contact pressure, initial vertical total pressure and distance to foundation centreline are employed, as model variables, to further investigate the control of permanent and variable actions on the residual pore pressure ratio. The model is verified against the Ghosh and Madabhushi high acceleration field test database. The outputs of this work is aimed to improve the current computer-aided seismic foundation design that relies on ground’s packing state and consistency. The results confirm that on seismic excitation of shallow foundations, the likelihood of effective stress loss is greater in deeper depths and across free field. For the benchmark problem, adopting a shallow foundation system instead of piled foundation benefitted in a 75% less emission rate, a marked proportion of which is owed to reduced materials and haulage carbon cost

Влияние метода отбора проб масла на диагностирование узла трения

The results of experiment showing an increase of metal content in oil MS-20 depending on current load on metal balls, and effect of sampling method on friction unit diagnostics are presented.Представлены результаты экспериментов, показывающие зависимости роста содержания металлов в масле МС-20 от действующей на металлические шарики нагрузки, а также влияние метода отбора проб на результаты диагностирования узла трения

Сравнительный анализ показателей качества авиационных керосинов, биотоплив и их смесей

Modern trends of civil aviation development indicate the need to improve fuel efficiency and environmental friendliness of the utilized fuels. The use of conventional jet fuel is meeting to a lesser degree the promising requirements concerning environmental friendliness at a constantly rising price for it. Apart from that, oil reserves are limited. According to many experts, the solution to the growing problems with oil fuels can be application of alternative types of aviation fuel. A number of companies around the world, together with aircraft manufacturers under the significant state support, are actively developing new types of fuel. At the moment the most widespread biofuels consisting of bioethanol are obtained from various plant and animal sources. Alternative fuels should not be inferior to petroleum fuels in its operational properties. A possible transition to them should not require significant costs for the modernization of aircraft and facilities of ground aviation fuel supply. Therefore, an urgent task is to compare the main indicators of the quality of oil fuels, biofuels and their mixtures to assess the possibility of using biofuels on aircraft. A comparative analysis was carried out on some quality indicators. Afterwards the comments were given on the impact of changes of these quality indicators on the performance properties of the fuels. It is shown that according to some quality indicators, biofuels under research have the advantages over oil ones. The relevance of comprehensive study of the performance properties of biofuels is obvious. The improvement of oil fuels and their comprehensive study have been under way for more than 60 years. Biofuels are just beginning their life, so it is reasonable to conduct thorough research on their use in aviation.Современные тенденции развития гражданской авиации указывают на необходимость повышения топливной эффективности и экологичности применяемых топлив. Применение традиционного авиакеросина все в меньшей степени удовлетворяет перспективным требованиям по экологичности при постоянно растущей на него цене. Кроме того, запасы нефти не безграничны. По мнению многих специалистов, решением нарастающих проблем с нефтяными топливами может быть использование альтернативных видов авиационного топлива. Ряд компаний в разных странах мира совместно с производителями авиационной техники при весомой государственной поддержке активно разрабатывают новые виды топлива. Наиболее распространены на данный момент биотоплива, состоящие из биоэтанола, полученные из различных растительных и животных источников. Альтернативные виды топлив по своим эксплуатационным свойствам не должны уступать нефтяным топливам. Возможный переход на них не должен требовать значительных затрат на модернизацию воздушных судов и средств наземного авиатопливообеспечения. Поэтому актуальной задачей является проведение сравнения основных показателей качества нефтяных топлив, биотоплив и их смесей для оценки возможности применения биотоплив на воздушных судах. Сравнительный анализ проводился по некоторым показателям качества, после чего были даны комментарии по влиянию изменений этих показателей качества на эксплуатационные свойства топлив. Показано, что по некоторым показателям качества исследуемые биотоплива имеют преимущества перед нефтяными. Очевидна актуальность проведения полных и всесторонних изучений эксплуатационных свойств биотоплив. Совершенствование нефтяных топлив и их всестороннее изучение продолжается уже более 60 лет, биотоплива только начинают свой жизненный путь, поэтому целесообразно проведение всесторонних исследований по их применению в авиации

Cerebral cavernous malformations proteins inhibit Rho kinase to stabilize vascular integrity

Endothelial cell–cell junctions regulate vascular permeability, vasculogenesis, and angiogenesis. Familial cerebral cavernous malformations (CCMs) in humans result from mutations of CCM2 (malcavernin, OSM, MGC4607), PDCD10 (CCM3), or KRIT1 (CCM1), a Rap1 effector which stabilizes endothelial cell–cell junctions. Homozygous loss of KRIT1 or CCM2 produces lethal vascular phenotypes in mice and zebrafish. We report that the physical interaction of KRIT1 and CCM2 proteins is required for endothelial cell–cell junctional localization, and lack of either protein destabilizes barrier function by sustaining activity of RhoA and its effector Rho kinase (ROCK). Protein haploinsufficient Krit1+/− or Ccm2+/− mouse endothelial cells manifested increased monolayer permeability in vitro, and both Krit1+/− and Ccm2+/− mice exhibited increased vascular leak in vivo, reversible by fasudil, a ROCK inhibitor. Furthermore, we show that ROCK hyperactivity occurs in sporadic and familial human CCM endothelium as judged by increased phosphorylation of myosin light chain. These data establish that KRIT1–CCM2 interaction regulates vascular barrier function by suppressing Rho/ROCK signaling and that this pathway is dysregulated in human CCM endothelium, and they suggest that fasudil could ameliorate both CCM disease and vascular leak

Exploring preference homogeneity and heterogeneity for proximity to urban public services

© 2018 Elsevier Ltd Given that the majority of the world's population lives in urban places, the quality of the urban environment has emerged as an issue of fundamental concern for citizens, academic researchers, and policy makers. This study explores residents’ preferences and valuation of living in proximity to urban amenities in the built environment. The study demonstrates that environmental evaluation techniques can be used as a tool to help relevant decision makers (e.g., urban managers, developers, city officials, planners, realtors and researchers) with policy making, effective decision making and efficient city management procedures. The models indicate how household preference for proximity to urban amenities change as a function of the cost of provision as exemplified by a change (increase or decrease) in annual property tax. The study reports the results for two different models: one which assumes preference homogeneity and the other preference heterogeneity in the sampled population. The results show that older residents and higher educated people are more likely to be willing to pay a higher property tax for having proximity to parks. Middle and low income residents prefer close proximity to bus stops and local shopping centres. This research suggests that a win-win strategy for residents and local government lies in increasing and maintaining residents’ accessibility to urban amenities, and in increasing an urban area's sustainability

Lifestyles, residential location, and transport mode use: A hierarchical latent class choice model

This study develops a hierarchical latent class choice model that captures the concurrent influence of lifestyles on household residential neighbourhood location and individual transport mode use decisions. The model is empirically evaluated using data from the 2010–12 CaliforniaHousehold Travel Survey. The model identifies six household-level classes that differ in terms of their preferences for different neighbourhood attributes when deciding where to live and their household characteristics. Coincidentally, the model also identifies six individual-level classes that differ in terms of the travel modes that they consider when deciding how to travel, their sensitivity to different level-of-service attributes, and their individual characteristics. Household preferences for neighbourhood types and individual preferences for travel modes show expected patterns of correlation. In general, households that prefer to live in suburban neighbourhoods are more likely to consist of individuals that are car-dependent, and households that prefer to live in inner-city neighbourhoods are more likely to consist of individuals that are multimodal. However, our analysis also reveals interesting patterns of deviation. For example, high-income migrant households and median-income white households display strong preferences for suburban neighbourhoods, but individuals belonging to these households also have a high likelihood of being multimodal, with a strong preference for bicycling. We discuss how these patterns of correlation can be used to inform transport and land use policy in novel ways