Procedia Engineering最新文献

The fire field simulation tool FDS is used to simulate and compare the different fans operating conditions of the semi-transverse ventilation of the proposed Nantong Seyuan Road Tunnel. The fire source is located at the most unfavorable position of the main road and the ramp. The heat release rate is 20 MW and the grid size is 0.2 m. Considering the natural wind speed of 1 m / s and 2 m / s, the air volume of the single fan is 20 m³ / s. The results showed that: (1) The flue gas temperature at the ceiling above the fire sources of all conditions was significantly higher than 100 ℃; when from the fire source area more than 10 m, the CO concentration was not more than 100 ppm and the height of the smoke layer was more than 2 m; (2) Opening the air feed fans was not conducive to reduce the flue temperature at the safe height. (3) Increasing the number of exhaust fans on both sides of the fire source was conducive to flue gas emissions; (4) when the exhaust fans were turned on, the addition of the ramp jet fan can not be significantly to reduce the flue gas temperature at the ramp. The aim of this study is to provide a theoretical basis for the optimization of the semi-transverse ventilation model of the fire in the Nantong Seyuan Road Tunnel.

In this work, three types of structural modified epoxy adhesives were used to investigate the effect of stress concentrations on the fatigue behavior of notched bulk specimens. SN curves of un-notched and notched specimens were determined at constant amplitude and R = 0.1 in the range between N_f = 10³ (LCF) and N_f = 10⁶ (HCF). The following key conclusions were made: (i) fatigue strength was reduced due to the presence of notches, especially at the HCF; (ii) adhesives showed different values of notch sensitivity with values for the adhesives lower than typical values of metals; (iii) for un-notched samples fatigue strength was between 62 and 78% of tensile strength for N_f = 10³ and around 50% for N_f = 10⁶; (iv) for notched samples fatigue strength was between 67 and 78% of the tensile strength for N_f = 10³ and around 40% for N_f = 10⁶; (v) fractography evidenced the presence of voids and shear yielding around the notches, (vi) unnotched samples showed the same fracture behavior for both LCF and HCF with crack formation at the external surface. For notched samples there was a significant distinction between LCF and HCF with cracks forming at the notch root.

The Tooth Flank Fracture, TFF, is a failure mode observed in the surface-hardened of gear tooth flanks. There is a fatigue phenomenon which initiates from a subsurface crack that occurs in the transition zone between the hardened layer and the core structure of the tooth. It is substantially initiated close to the mid-height of the tooth in the single pair of contact area from a crack that progresses in a direction normal to the active surface flanks and also spreads in the thickness of the tooth up to the breakage of the non-active flank, slightly above the root fillet.

The two main modes of fatigue damages for gears are: (i) contact fatigue and (ii) tooth bending root fatigue, are well established and addressed in the international standards such as ISO 6336 part 2 and 3. However, up to now, there is no detailed calculation method to determine the load capacity related to the Tooth Flank Fracture, TFF.

The main objective of this work is to develop an efficient and a standardized methodology to identify the occurrence risk of the Tooth Flank Fracture (TFF) in cylindrical gears. Then, to estimate the risk of appearance of TFF, we have studied two fatigue criteria which are introduced in a developed numerical model. The developed approach, which is based on the Hertz theory with the half-space approach, has been validated by finite elements simulations, revealing a good compliance of the “simplified” criteria proposed initially by Dang Van to characterize this failure mode. Good agreement of this criterion is also observed after a comparative study relative to some experimental tests carried out in literature. An advanced parametric study is carried out to properly identify the real impact of the case hardening depth on this damage mode.

Emergency evacuation plan plays a key role for fire risk management and successful evacuation. In this work, a topological model of evacuation routes is established and the corresponding matrix function is also proposed in order to evaluate evacuation ability. Simultaneously, risk assessment of fire scenarios is made based on numerical simulation. And on this basis, the variation laws of risk indicators such as temperature, thermal radiation, the concentration of toxic gas are analyzed in details and dynamic risk assessment of evacuation routes is made. Introducing the concept of equivalent routes, the scheme of the best route for evacuee at each location is the one along with the shortest time and minimal risk and suggested based on the Dijkstra algorithm. And then, one case is presented and result indicates that this model can aid people to avoid crowdedness and evacuate as soon as possible under fire accident. The risk-based model is also useful for the evacuation planning.

The province of Tarlac in the Philippines is one of the commonly flooded areas due to its geographical characteristics. The province is surrounded by high mountains along its eastern and western outskirts but predominantly the province is a vast flat area.

The present study focuses on the development of flood model for the urban areas of Tarlac City wherein a flood overlay zone is developed based on the flood hazard model. Specifically, the study focuses on attaining the following objectives: to develop a flood inundation model; to determine the hazards on the existing land use as well as determine the susceptibility to flood hazard and determine the risks on the urban barangays; and to look into the implications of land use policies towards risk management.

Historical, analytical and qualitative methods were employed to attain the objectives of the study. Stakeholders in the City Disaster Risk Reduction and Management Council (CDRRMC) were involved in the formulation of policies and strategies which may lessen the flood hazards as well as the risks towards the urban communities. The outcome of the workshop will be incorporated to the updated comprehensive land use plan (CLUP) of Tarlac City.

In view of special low pressure environment in high-altitude plateau, the paper carries out simulation and field experiment of AFFF in high-altitude low pressure environment. The results show that: when ambient pressure changes from 101kPa to 24kPa, with the reduction of ambient pressure, the foam expansion of AFFF decreases, and drainage time of AFFF decreases first and increases later; the 59kPa is the extreme point of whole change process and the drainage time of AFFF fire extinguishing agent reaches a minimum under this ambient pressure. During the stage from 101kPa to 59kPa, the drainage time of AFFF decreases with the reduction of ambient pressure. It shows through field test that in the stage from 101 kPa to 59kPa, the performance parameters of AFFF foam are consistent with those in simulation experiment.

We focus on applications from the automotive industry, on mechanical components submitted to vibration loads. On one hand, the characterization of loading for dimensioning new structures in fatigue is enriched and updated by customers data analysis. In a second hand, the loads characterization also aims to provide robust specifications dedicated to the simulation or test rigs. We aim to provide vibration specifications that are adapted to a calculation time or physical test durations in accordance with the pace imposed by the projects timeframe. The vibration specifications need to be robust by taking care of the diversity of vehicles and markets considered in the projects. In the trucks industry, the dynamic behavior can vary significantly from one configuration to another. For non-stiff structures, the lifetime depends, among other things, on the frequency content of the loads, as well as the interactions between the components of the multi-input loads. In this context, this paper proposes to compare sets of multi-input loads applied on the non-stiff structure, i.e for which the frequency content of loads impacts the damage.

The importance of private sector engagement on risk reduction is increasingly mentioned over the last years. The Sendai Framework for Disaster Risk Reduction 2015-2030 stresses that the private sector should be a crucial partner in achieving disaster resilience. However, the contribution by the private sector is still rare and mostly undertaken by large multinational firms with just a few positive impacts on the local level.

Particularly manufacturing firms are heavily exposed to floods in Indonesia; Jakarta and Semarang are prominent examples. Broader flood risk reduction measures are still insufficiently developed. Therefore, it is argued that firms can reduce the flood risk through collective adaptation measures. We understand collective adaptation as collaborative activities to reduce risks that firms are either initiating or participating together with other firms, the community, NGOs and authorities.

Our own research has revealed that particularly small and medium-sized enterprises (SMEs) rarely engage in collective flood adaptation. Based on our findings, this paper examines which circumstances determine the willingness of SMEs to contribute to flood risk reduction. Instruments in order to increase the willingness to collective adaptation are also discussed.

Scenario-based experiments with 120 SMEs have been conducted in Jakarta and Semarang. These scenarios contain different risk reduction measures (polder system, river expansion and sensitization program), each with different actors’ constellation of contribution. Comparative logistic regressions have been applied to determine context-specific factors, e.g. risk behavior, firm-specific characteristics or level of flood-proneness that influence the willingness to contribute to flood risk reduction.

Overall, the paper provides deeper insights in understanding firms’ engagement in flood risk reduction and gives answers of how firms can be motivated to become an active player on building resilience.

Local government have a pivotal role in city planning. However, meeting the conflicting priorities such as plan for urbanization, promote economic prosperity, ensure environmental sustainability besides creating safe, vibrant and liveable places, create major challenges for local administration. While rapid urbanization continue to displace people from their local places, the frequency of disaster events at the local scale and increasing disaster risks place unique challenges on people and their places. This emphasises the need for local government to understand the local places and invest in planning for cities that improve resilience and enhance human connectivity to their places. Meeting these multidimensional needs in local spaces require embedding local and scientific knowledge, past experiences and community expectation to plan and design cities that also deliver multiple social outcomes. Both place-based approach to city planning and creating disaster resilient cities have gathered momentum, however, they continue to occur in isolation. Maximizing these multiple social, environmental and economic outcomes, emphasize the need to align both resilience principles for sustainable urbanization and place based approach planning concepts to plan for places for people. Drawing from these principles and organizational change theory, a conceptual framework is proposed that provide a new lens for local government to plan for place based resilient cities. This place based approach for resilient cities framework incorporates the thinking for change as a dynamic process across the time scales and by understanding the relationship between people and their place. The model proposed is in an Australian context, yet has significant implication for communities at all levels when planning for places for people.