The Concept and Practice of Treatment for Damage in Railway Tunnel Linings Caused by High-pressure Karst Water北大核心CSCD

In recent years, railway tunnels in karst areas have frequently suffered flooding after high-intensity rainfall, which seriously affects the safety of tunnel operation and the order of transportation, and even interrupts the traffic. Based on the water hazard case in the Yuanbaoshan Tunnel on the Zhijin-Bijie Railway Line, this paper explores the causes of lining damage in terms of geology, rainfall, and the design and construction of water hazard sections, and puts forward the treatment technology for tunnel water hazards with the core concept of "making full use of existing structures and employing open drainage methods in key sections". Besides, this paper simulates and analyzes the formation of hazards and the treatment effect through numerical simulation. The results show that the subjective causes for the damage in tunnel linings include an insufficient understanding of the water-bearing formations at the geological investigation stage, the underestimation of water hazard risks posed by high-intensity rainfall during construction, and the unimproved waterproof and drainage system in the design alteration, while the objective reasons include the development of karst near the tunnel section that passes through the stratum, the strong connectivity of water conduits, and the high-intensity rainfall in a certain period of time on the tunnel site. As for the simulation results, they show that the increase of external water pressure caused by the sudden rise in groundwater level after rainstorm significantly increases the internal force of linings, and eventually leads to a much lower safety factor of sidewall linings and large scale damage, which is in consistency with the characteristics of the actual on-site damage. After on-site emergency treatment, the tunnel structure has become stable and even encountering unprecedentedly heavy rainfall twice, the tunnel has still remained in a good condition. Since then, no water hazards and other disasters have occurred, which proves that the treatment plan is valid. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

New Zealand Advances in Performance-Based Seismic Design

This paper provides a summary of the objectives and principles which underpin the 2004 edition of the New Zealand earthquake design standard, AS/NZS 1170 Part 5. As with many modern earthquake design standards, the New Zealand earthquake design standard recognizes that earthquake resistant design that only addresses life safety goals without addressing both operational continuity of essential facilities and damage control, falls short of public expectations. Such standards not longer meet societal expectations. The paper outlines how these issues have been addressed within New Zealand, and some of the issues addressed when preparing appendices to the standard to provide guidance for materials standard writers to ensure consistency with the proposed approach. Recognizing the significance of non-structural components and parts of buildings in both damage control and operational continuity has been an important step forward in attaining the performance levels required.     

Design of vehicle of on-glass 4×4 MIMO antennas for WiBro applications

This paper proposes on-glass 4×4 MIMO antennas with broad bandwidth and high radiation gain, suitable for receiving WiBro internet applications in a commercial sedan. For the individual antenna body, we used a triangular-shaped patch that most efficiently satisfies broad-matching bandwidth. Then the inside of the triangular patch was partially removed to broaden the driver’s field of view. To obtain detailed design parameters that exhibit optimum radiating performance, we used a genetic algorithm (GA) in conjunction with a full wave EM simulator and varied the feeding locations of four antennas so as to increase throughput capacity for effective data transmission. The proposed antenna showed ?10 dB matching bandwidth and a measured average gain of about 4.77 dBi along the bore-sight direction (θ = 90°, ? = 180°) in the entire WiBro band (2.3–2.4 GHz). To confirm the MIMO performance in a real situation, we measured the commercial WiBro signal using the proposed antennas in an urban environment. The correlation coefficients among the antennas were calculated, and the result revealed an average value of 0.105.     

A numerical study of stochastic larval settlement in the California Current system

Key to the predictive understanding of many nearshore marine ecosystems is the transport of larvae by ocean circulation processes. Many species release thousands to billions of larvae to develop in pelagic waters, but only a few lucky ones successfully settle to suitable habitat and recruit to adult life stages. Methodologies for predicting the larval dispersal are still primitive, and simple diffusive analyses are still used for many important applications. In this study, we investigate mechanisms of larval dispersal using idealized simulations of time-evolving coastal circulations in the California Current system with Lagrangian particles as models for planktonic larvae. Connectivity matrices, which describe the source-to-destination relationships for larval dispersal for a given larval development time course, are used to diagnose the time–space dynamics of larval settlement. The resulting connectivity matrices are shown to be a function of several important time scales, such as the planktonic larval duration, the frequency and duration of larval release events and inherent time scales for the coastal circulations. Many important fishery management applications require knowledge of fish stocks on a year-to-year or generation-to-generation basis. For these short time scales (typically less than 1 year), larval dispersal is generally far from a simple diffusive process and the consideration of the stochastic and episodic nature of larval dispersal is required. This work provides new insights into the spatial–temporal dynamics of nearshore fish stocks.     

Thermo-oxidative degradation of a carbon black compounded EPDM rubber hose

A method to measure the crosslink density of carbon black was used to analyze the aging behavior of a radiator hose made of carbon black filled EPDM (ethylene-propylene diene monomer) rubber under thermo-oxidative stresses. The crosslink density and the strength of the skin of the rubber specimens initially decreased slightly but then increased over time. The elongation at the break considerably reduced and did not show any similarity to the behaviors of the crosslink density. A possible cause of this reaction might be from the formation of rigid sulphoxide crosslinks and the crosslinks produced by the reaction of unvalcunized sulfurs. Aging the rubber specimens at 180°C caused a slight increase in the crosslink density and a large decrease in tensile strength and elongation. The aging experiment also caused a rapid increase of microhardness in the surface skin region. The formation of carbonyl groups in EPDM molecule chains and the formation of rigid sulphoxide crosslink, rather than the crosslink density variation, may have had a large influence. The changing behaviours of the mechanical properties, molecule chains and crosslinks showed significantly different characteristics in the skin and the interior with aging temperature and time.     

充满挑战的中国汽车导航业

中国消费者导航使用频率高 根据Strategy Analytics对北美、欧洲和中国市场进行的调查,中国的驾车者对导航仪的使用最为频繁. 2011年11月StrategyAnalytics分别在西欧和美国各抽取1200名、在中国抽取2000名用户,就消费者对嵌入式导航、便携式导航及手机导航的兴趣、习惯和满意度等问题进行了调研.调研结果显示,嵌入式导航的使用频率比另两类导航更高.     

La mobilité comme modalité de l’ancrage : enrichir l’évaluation de la durabilité des espaces périurbains

This paper proposes to deepen the relationship between mobility and tethering in peri-urban spaces, and provide new methodological avenues, capable of contributing to the build-up of key knowledge elements, that we feel are crucial in a company’s capacity to implement their own sustainability requirements. These key knowledge elements are primarily based on the results stemming from research entitled “Peri-urbanism testing models for living; peri-urban viability, in theory and in practice”. The aim of this research was to assess, at least potentially, the sustainability of periurban spaces, which have seen recent development, as they have benefited from a growing trend towards removing space and time restrictions, through the generalisation of mobility, at the centre of many societal issues today.     

Distribution of dinoflagellate cysts in surface sediments of the Mackenzie Shelf and Amundsen Gulf, Beaufort Sea (Canada)

In order to document long-term climate cycles and predict future climate trends for the Arctic, we need to look at the geological records to establish the link between historical and pre-historical sea-surface parameters. Dinoflagellate cysts (dinocysts) are used as proxy indicators of sea-surface parameters (temperature, salinity, sea-ice cover, primary productivity) jointly with transfer functions and a modern dinocyst reference database, to reconstruct the evolution of sea-surface conditions at decadal and millennial timescales. Here we present the surface distribution of recent dinocyst assemblages from 34 surface sediment samples collected on the Mackenzie Slope/Amundsen Gulf during the 2004 CASES (Canadian Arctic Shelf Exchange Study) cruise. Dinocyst concentrations in surface sediments are relatively high outside the Mackenzie plume area and increase gradually eastward toward Amundsen Gulf. The cysts of autotrophic dinoflagellates are dominant throughout the study area, while the maximum abundance of heterotrophic taxa is found within the Mackenzie plume. Hierarchical clustering analyses allowed defining two dinocyst assemblages. Assemblage I is located on the Mackenzie Slope and southern Amundsen Gulf, while Assemblage II is located within the Cape Bathurst Polynya area in northern Amundsen Gulf. Both assemblages are dominated by Operculodinium centrocarpum, but are distinguished on the basis of the relative abundance of Islandinium minutum, a taxon generally associated with sea ice. I. minutum is found in lower abundance in the Cape Bathurst Polynya.     

The changes of activity-travel participation across gender,life-cycle,and generations in Sweden over 30 years

Transportation - This study utilised the Swedish national travel survey covering a period of over 30 years. We investigated the long-term trends in activity-travel patterns of individuals...