Direction Of Street Research Articles

Главная улица Твери в XVII — середине XVIII в.

The main street of Tver originates in the far Middle Ages, but a relatively clear idea of this “highway” may be traced only starting from the 17th century, when the development and urban planning structure of the Russian city, in accordance with peculiar views of reality, were reflected in the works of icon painters, as well as foreign travelers. The era of Peter I strengthened the documental use when depicting the layout of a late medieval city, yet the fixation of urban planning structure was largely spared from instrumental survey, since domestic cartographers of the first quarter of the 18th century, as a rule, preferred to focus on the iconographic tradition. Residential, religious and other urban objects are represented in these materials in quite a schematic and sometimes generalized way. The situation changed by the middle of the 18th century, but this period (the second quarter — the middle of the 18th century) in the cartographic heritage of Tver still remains a blank spot. For this reason, it is currently quite difficult to outline the route of the city’s main highway in the pre-Catherine era, since in the mid-1760s the direction and configuration of the main street of Tver were changed by the initiative of Catherine II. Nevertheless, this study attempts to reconstruct the location of the pre-Catherine “highway”, as well as to present the nature of almost completely lost urban development associated with this street in the late Middle Ages and in the first half of the 18th century.

Flow map of foil undergoing combined fast and slow pitching

The drag-thrust transition and wake structures of a pitching foil undergoing combinations of fast and slow pitching are systematically investigated. The foil locomotion having combinations of fast and slow pitching is made by setting a variable s defined as the fraction of the pitching time required on the upper side of the wake centerline. On the other hand, time 1-s is required for the foil to pitch on the lower side of the wake centerline. Compared to the symmetric pitching (s = 0.5) case, the time-mean thrust rapidly increases and the drag-thrust boundary advances with increasing |s − 0.5|. The Kármán vortex street slants and produces thrust when |s − 0.5| is sufficiently large, which supersedes the previous thumb rule that only reverse Kármán vortex street can produce thrust. The faster forward stroke determines the slant direction of the vortex street. The detailed wake structures produced by the pitching foil are discussed, showing how the combined pitching affects vortex dynamics, drag-thrust transition, slant direction, and wake jet. This work provides a physical basis for understanding the hydrodynamics of native swimmers which may be useful to design bio-inspired underwater robots.

Flow transitions and mapping for undulating swimmers

Natural swimmers usually perform undulations to propel themselves and perform a range of maneuvers. These include various biological species ranging from micro-sized organisms to large-sized fishes that undulate at typical kinematic patterns. In this paper, we consider anguilliform and carangiform swimming modes to perform numerical simulations using an immersed-boundary methods based computational solver at various Reynolds number regimes. We carry out thorough studies using wavelength and Strouhal frequency as the governing parameters for the hydrodynamic performance of undulating swimmers. Our analysis shows that the anguilliform kinematics achieves better hydrodynamic efficiency for viscous flow regime, whereas for flows with higher Reynolds number, the wavelength of the wavy motion dictates which kinematics will outperform the other. We find that the constructive interference between vortices produced at anterior parts of the bodies and co-rotating vortices present at the posterior parts plays an important role in reversing the direction of Benard-von Karman vortex street. Since most of the thrust producing conditions appear to cause wake deflection; a critical factor responsible for degrading the hydrodynamic efficiency of a swimmer, we discuss the underlying mechanics that would trigger this phenomenon. We demonstrate that the choice of kinematic and flow conditions may be restricted for the natural swimmers due to their morphological structures, but our findings provide a guideline on their selection for bio-inspired underwater vehicles.

A stochastic user equilibrium assignment problem in discrete network design problem

We formulate the transportation discrete network design problem (DNDP) as a mixed-integer bi-level mathematical problem, based on the concept reserve capacity. The upper level goal programme maximises the reserve capacity by designing the direction of street and increasing the street capacity through lane addition. The lower level problem is stochastic user equilibrium traffic assignment problem within a probit-based path choice decision framework which generates user equilibrium flow patterns. Because of non-convexity nature of the model, meta-heuristic methods used to solve the problem and we used Monte Carlo simulation approach to compute path choice probabilities and stochastic user equilibrium solved by method of successive averages. A hybrid genetic algorithm with simulated annealing and an evolutionary simulated annealing algorithm are proposed. Numerical examples are presented to verify the proposed model and algorithm.

The traffic impact assessment to the project of Nguyen Hue walking street

The government of Ho Chi Minh City has a plan to develop the current Nguyen Hue avenue to the walking street. In order to evaluate the feasibility of the project, it is necessary to conduct the traffic impact assessment. By using the simulation technique, several scenarios have been developed to identify the relevant solutions for the traffic improvement in this area. The traffic assessment is conducted via a process of OD demand analysis by using four-step model, which is improved from the previous model, HOUTRANS (2004) (The Study on the Urban Transport Master Plan and Feasibility Study in City Metropolitan Area). The proposed scenario, which can be considered as the most relevant solution for this project, is to convert some roads around Nguyen Hue avenue into one-way streets. Specifically, Ton That Thiep, Ngo Duc Ke street and Nguyen Hue avenue are changed into one-way streets in the direction of Pastuer and Dong Khoi street. Hai Trieu, Mac Thi Buoi, Huynhh Thuc Khang street are converted into one-way streets in the opposite direction.

EFFECTS OF CHARACTERISTICS OF URBAN BLOCK ON WIND ENVIRONMENT IN THE STREET CANYON

To promote ventilation in street canyon is one of effective urban heat island measures. The analysis on relationship between properties of urban block and wind environment in street canyon is required. In this study, relationship between wind environment in street canyon and characteristics of urban block e.g. building cover ratio, variation of building heights, as well as roadside properties e.g. direction of street, width of street, height of building, is studied by CFD simulation results carried out in central Osaka city. Ventilation in street canyon is promoted by positive and negative pressure areas which are formed by variation of building heights. Both the vertical wind path caused by high-rise building and the horizontal wind path formed along wide road parallel to upper wind direction should be considered for improvement of ventilation in street canyon. It is also confirmed that attention to windward and downwind areas should be noted.

ANALYSIS ON THE RELASHIONSHIP BETWEEN PROPERTIES OF URBAN BLOCK AND WIND PATH IN THE STREET CANYON FOR THE USE OF THE WIND AS THE CLIMATE RESOURCES

To promote ventilation in the street canyon is one of the effective heat island measures. The analysis on the relationship between properties of urban block and wind environment in the street canyon is required. In this study, relationship between wind environment in the street canyon and the direction of street, the width of street and the building height beside street is studied by CFD simulation result and observation result. Wind velocity ratio, which is calculated in street wind velocity by upper wind velocity, is used for the index of wind environment in the street canyon.