Property Evolution of Sulphoaluminate Grouting Material under Pressure Circulation北大核心CSCD

Water-sealed underground oil tank projects are quite different from traditional underground projects since the water-sealing conditions are very strict and the difficulties caused by the geological specificity, structural specificity and construction specificity are key factors affecting the project. In light of the significant early initial setting time and rapid temperature increase of sulphoaluminate cement-based grouting material for a large domestic water-sealed underground oil tank with pressurized cyclic grouting, a laboratory grouting simulation is conducted. It is found that the properties of the sulphoaluminate cement-based grouting material are quite different under different pressure cycles, the hydration exothermic peak time gets shorter with an increase of circulation time, the compressive strength decreases with an increase of circulation time, and the longer the circulation time the more obvious the de-crease of compressive strength. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Coastal Tourist Interest in Value-Added,Aquaculture-Based,Culinary Tourism Opportunities

Despite increasing focus on sustainable aquaculture investment in the U.S. coastal zones, the aquaculture industry continues to face skepticism among consumers due to perceived negative environmental impacts, and health and food safety concerns. Partnering with culinary tourism and local food promotion efforts has potential for improving public outreach about the benefits of aquaculture, especially in coastal destinations where sustainable marine aquaculture and tourism are both occurring. Culinary tourism implies that local foods reflect the local livelihood and culture, and may be important to the tourist's experience. Aquaculture is becoming increasingly valuable to coastal destinations for assuring the steady availability of local seafood to meet demand and retaining commercial fisheries as a means to differentiate themselves to tourists. This study examined the role of subjective knowledge and attitude about aquaculture, and their effect on intention to participate in value-added culinary aquaculture tourism experiences. The study found that tourists' subjective knowledge and attitude about aquaculture influenced intentions to participate in culinary aquaculture tourism. In order for farmers or tour operators to be successful in diversifying with value-added culinary aquaculture, attention needs to be paid to educating consumers, which may be possible through strategic partnerships with tourism organizations, chefs, and restaurants.     

The Dependency of People on the Great Barrier Reef,Australia

Understanding how people are dependent on Large Scale Marine Protected Areas (LSMPAs) is important for understanding how people might be sensitive to changes that affect these seascapes. We review how resource dependency is conceptualized and propose that it be broadened to include cultural values such as pride in resource status, scientific heritage, appreciation of aesthetics, biodiversity, and lifestyle opportunities. We provide an overview of how local residents (n = 3,181 face-to-face surveys), commercial fishers (n = 210, telephone surveys), and tourism operators (n = 119 telephone surveys) are potentially dependent on the Great Barrier Reef (GBR), a region currently experiencing significant environmental, social, and economic change. We found that commercial fishers and tourism operators were dependent not only financially on the GBR, but also because of their age, years in the industry and region, lack of education, and the number of dependents. These stakeholders lacked flexibility to secure alternative employment. All stakeholder groups, regardless of economic imperatives, were dependent on the GBR because of their cultural connections. We propose that resource dependency also provides an umbrella concept to describe the cultural services provided by an ecosystem, which can be described through place-based dependence and place-identity.     

Genetics of traffic assignment models for strategic transport planning

This paper presents a review and classification of traffic assignment models for strategic transport planning purposes by using concepts analogous to genetics in biology. Traffic assignment models share the same theoretical framework (DNA), but differ in capability (genes). We argue that all traffic assignment models can be described by three genes. The first gene determines the spatial capability (unrestricted, capacity restrained, capacity constrained, and capacity and storage constrained) described by four spatial assumptions (shape of the fundamental diagram, capacity constraints, storage constraints, and turn flow restrictions). The second gene determines the temporal capability (static, semi-dynamic, and dynamic) described by three temporal assumptions (wave speeds, vehicle propagation speeds, and residual traffic transfer). The third gene determines the behavioural capability (all-or-nothing, one shot, and equilibrium) described by two behavioural assumptions (decision-making and travel time consideration). This classification provides a deeper understanding of the often implicit assumptions made in traffic assignment models described in the literature. It further allows for comparing different models in terms of functionality, and paves the way for developing novel traffic assignment models.     

冰荷载作用下护岸结构数值模拟

季节性冰冻河流春季开江产生的流冰会严重威胁堤防建筑物的安全,开展流冰对结构物的碰撞规律研究十分必要。为此,以松花江汤原县胜利堤护岸结构为例,利用ANSYS/LS-DYNA软件,基于结构地质地形,考虑松花江春季江面开化流冰情况,建立计入冰荷载作用下的护岸结构数值分析模型,开展护岸结构在冰排撞击作用下的有限元分析研究,理清结构承载变化规律,为季节性冰冻地区护岸结构的设计及后期维护提供理论参考和技术支持。     

On the observability of the fortnightly cycle of the Tagus estuary turbid plume using MODIS ocean colour images

Using three years (2003 to 2005) of MODIS-Aqua normalized water-leaving radiance at 551 nm this paper shows a fortnightly cycle in the Tagus estuary turbid plume. The Tagus estuary is one of the largest estuaries of the west coast of Europe and is located in the most populated area of Portugal, including the capital Lisbon. The turbid plume has been detected by the backscattering characteristics of the surface waters in the vicinity of the estuary mouth. In fortnightly scales, the turbid plume has smaller dimensions during and after neap tides and higher dimensions during and after spring tides. This is most probably associated with the fortnightly spring–neap tidal cycle and the consequent increase in turbidity inside the estuary during spring tides. During the summer weak spring tides (tidal amplitude approximately 2.5 m) no turbid plume is observed for an entire fortnightly cycle. Outside the summer months, precipitation, river discharge and winds, were found to increase the turbid area, but the fortnightly cycle appears to be superimposed on the large time-scale variability, and present throughout the year.     

Non-local simulation of the stable boundary layer with a third order moments closure model

A new higher order closure model for the stable boundary layer is presented and compared with Large Eddy Simulation data. The model includes numerical solutions for the mean values, second and third order moments equations. A satisfactory agreement is found between the calculated vertical profiles of the turbulent quantities with those provided by the LES. Furthermore the new model results are compared with profiles obtained with a lower order closure model in order to verify the effective importance of including third order dynamical equations in the model.     

Community Perspectives Toward a Marine Reserve: A Case Study of San Felipe,Yucatán,México

San Felipe marine reserve, in Yucatán, México, is unique, and particularly suited for a case study because the local community created it without a mandate from higher levels of government. This article presents the results of a survey of local interest groups using the method of paired comparisons and rank correlation analysis, to reveal local judgments about the severity of damages to coastal habitats and the level of impacts of activities that cause the damages. The results show that fishers differ significantly from other interest groups in their rankings of the severity of damages to habitats and of impacting activities. These findings suggest that despite the overlapping interests in protecting the resources and the critical habitats, the different perspectives of local interest groups about the severity of damages must be considered in the management of San Felipe marine reserve.     

Disused shrimp ponds: Options for redevelopment of mangroves

Associated with the rapid increase in the production of cultured marine shrimp has been large‐scale conversion of mangroves to shrimp ponds. Production in many regions has proved to be unsustainable, largely due to inappropriate construction methods, poor environmental conditions, overstocking, and disease. A number of shrimp ponds consequently are unproductive and lie idle. Accurate assessments of pond disuse are difficult to obtain; however, unofficial estimates have suggested that as many as 70% of ponds may be disused after a period in production. Pond construction, shrimp culture, and pond disuse lead to alterations to the physical and chemical properties of soil, hydrological conditions, and the flora and fauna composition of the pond area. The case for restoration, or rehabilitation to a sustainable use, is strong. Consideration must be given to the causes of production failure, the environmental conditions remaining following disuse, the needs and preferences of pond owners and coastal managers, and technical constraints.     

Haptic steering support for driving near the vehicle’s handling limits; skid-pad case

Current vehicle dynamic control systems from simple yaw control to high-end active steering support systems are designed to primarily actuate on the vehicle itself, rather than stimulate the driver to adapt his/her inputs for better vehicle control. The driver though dictates the vehicle’s motion, and centralizing him/her in the control loop is hypothesized to promote safety and driving pleasure. Exploring the above statement, the goal of this study is to develop and evaluate a haptic steering support when driving near the vehicle’s handling limits (Haptic Support Near the Limits; HSNL). The support aims to promote the driver’s perception of the vehicle’s behaviour and handling capacity (the vehicle’s internal model) by providing haptic (torque) cues on the steering wheel. The HSNL has been evaluated in (a) driving simulator tests and (b) tests with a vehicle (Opel Astra G/B) equipped with a variable steering feedback torque system. Drivers attempted to achieve maximum velocity while trying to retain control in a circular skid-pad. In the simulator (a) 25 subjects drove a vehicle model parameterised as the Astra on a dry skid-pad while in (b) 17 subjects drove the real Astra on a wet skid-pad. Both the driving simulator and the real vehicle tests led to the conclusion that the HSNL assisted subjects to drive closer to the designated path while achieving effectively the same speed. With the HSNL the drivers operated the tires in smaller slip angles and hence avoided saturation of the front wheels’ lateral forces and excessive understeer. Finally, the HSNL reduced their mental and physical demand.