Effect of unprotected interior beams on membrane behaviour of composite floor system in fire, I: Experimental investigation

A number of previous studies on tensile membrane action have been conducted and they are very valuable towards understanding the behaviour of isolated slabs as well as of floor assemblies. However, the role of unprotected interior beams in the development of TMA still has not clearly determined. This paper presents an experimental study on the effect of unprotected interior beams on the behaviour of composite floor assemblies in fire. The experimental observations and results of two one-fourth scale composite slab-beam systems, 3.15 m by 3.15 m in plan, subjected to transient-heating test are presented.The test results show that the presence of interior beams can reduce the slab deflection and greatly enhance the slab load-bearing capacity. The interior beams have a major role in helping the slab in passing through the ‘transition’ stage, and thus the slab can mobilize more tensile membrane forces. Without the interior beams, the compressive ring failure may occur resulting in a little contribution from TMA in the slab load-bearing capacity

Effect of unprotected interior beams on membrane behaviour of composite floor system in fire, II: Numerical assessment

The authors’ companion paper presented the observations and results from two one-forth scale composite beam-slab systems tested in fire. This paper introduces the numerical assessment based on these experimental results. A non-linear finite element model is developed using ABQUS/Explicit to simulate the specimen behaviour. Material properties at elevated temperatures are assumed to vary according to EN 1994-1-2 (2005). The FE model was first validated with the test results, and then was used to examine the effect of unprotected interior beams on tensile membrane action. It is found that the numerical predictions agree well with the test results. The presence of interior beams significantly affects the magnitude as well as the distribution of stress of the slab elements, i.e. mesh reinforcement and concrete slab. The part with maximum tensile force is not necessarily at the slab centre. It may be part of the concrete slab above the edge beams. Shortcomings of the numerical model in predicting the failure modes are indicated

Những thuận lợi và khó khăn khi lập và thực hiện kế hoạch sử dụng đất hàng năm cấp huyện

Kể từ khi Luật Đất đai năm 2013 được ban hành và có hiệu lực từ ngày 01/7/2014, công tác lập kế hoạch sử dụng đất hàng năm phải được thực hiện ở đơn vị hành chính cấp huyện. Kế hoạch sử dụng đất hàng năm là cơ sở pháp lý cho việc giao đất, cho thuê đất, thu hồi đất và chuyển mục đích sử dụng đất. Tuy nhiên, qua thời gian đầu triển khai các quy định về lập và thực hiện kế hoạch sử dụng đất hàng năm cấp huyện, những quy định này đã bộc lộ một số bất cập cần được tháo gỡ, đặc biệt là các nội dung liên quan đến quyền của người sử dụng đất. Bài viết này tập trung phân tích những thuận lợi, khó khăn, bất cập khi lập và tổ chức thực hiện kế hoạch sử dụng đất hàng năm cấp huyện trên cả góc độ lý luận và thực tiễn. Qua đó, tác giả đề xuất các giải pháp phù hợp đối với những bất cập đã được phân tích nhằm kịp thời tháo gỡ các khó khăn, tồn tại trong quá trình lập và thực hiện kế hoạch sử dụng đất hàng năm cấp huyện, đặc biệt là những vấn đề liên quan đến quyền và lợi ích hợp pháp của người sử dụng đất

Rateless codes-based secure communication employing transmit antenna selection and harvest-to-jam under joint effect of interference and hardware impairments

In this paper, we propose a rateless codes-based communication protocol to provide security for wireless systems. In the proposed protocol, a source uses the transmit antenna selection (TAS) technique to transmit Fountain-encoded packets to a destination in presence of an eavesdropper. Moreover, a cooperative jammer node harvests energy from radio frequency (RF) signals of the source and the interference sources to generate jamming noises on the eavesdropper. The data transmission terminates as soon as the destination can receive a sufficient number of the encoded packets for decoding the original data of the source. To obtain secure communication, the destination must receive sufficient encoded packets before the eavesdropper. The combination of the TAS and harvest-to-jam techniques obtains the security and efficient energy via reducing the number of the data transmission, increasing the quality of the data channel, decreasing the quality of the eavesdropping channel, and supporting the energy for the jammer. The main contribution of this paper is to derive exact closed-form expressions of outage probability (OP), probability of successful and secure communication (SS), intercept probability (IP) and average number of time slots used by the source over Rayleigh fading channel under the joint impact of co-channel interference and hardware impairments. Then, Monte Carlo simulations are presented to verify the theoretical results.Web of Science217art. no. 70

Consistent explicit staggered schemes for compressible flows Part I: the barotropic Euler equations.

In this paper, we build and analyze the stability and consistency of an explicit scheme for the compressible barotropic Euler equations. This scheme is based on a staggered space discretization, with an upwinding performed with respect to the material velocity only (so that, in particular, the pressure gradient term is centered). The velocity convection term is built in such a way that the solutions satisfy a discrete kinetic energy balance, with a remainder term at the left-hand side which is shown to be non-negative under a CFL condition. Then, in one space dimension, we prove that if the solutions to the scheme converge to some limit as the time and space step tend to zero, then this limit is an entropy weak solution of the continuous problem. Numerical tests confirm this theory, and show in addition (in 1D, and thus in absence of contact discontinuities) a first-order convergence rate

Consistent explicit staggered schemes for compressible flows Part II: the Euler equation

In this paper, we build and analyze the stability and consistency of an explicit scheme for the Euler equations. This scheme is based on staggered space discretizations, with an upwinding performed with respect to the material velocity only. The pressure gradient is defined as the transpose of the natural velocity divergence, and is thus centered. The energy equation which is solved is the internal energy balance, which offers two main advantages: first, we avoid the space discretization of the total energy, the expression of which involves cell-centered and face-centered variables; second, the discretization ensures by construction the positivity of the internal energy, under a CFL condition. However, since this scheme does not use the original (total) energy conservative equation, in order to obtain correct weak solutions (in particular, with shocks satisfying the Rankine-Hugoniot conditions), we need to introduce corrective terms in the internal energy balance. These corrective terms are found by deriving a discrete kinetic energy balance, observing that this relation contains residual terms which do not tend to zero (at least, under reasonable stability assumptions) and, finally, compensating them in the discrete internal energy balance. It is then shown in the 1D case, that, if the scheme converges, the limit is indeed a weak solution. Finally, we present numerical results which confort this theory

Participatory Land Use Planning for Climate-Smart Villages: Guidelines and References

Participatory land-use planning (PLUP) refers to a bottom-up method of analyzing land and water resources. In its current form, PLUP integrates inputs about climate change and sea level rise to help the community utilize the resources within its vicinities. In utilizing its resources, the community will be able to improve the people’s livelihoods and help them sustain such resources for the benefit of the next generations. This publication in implementing PLUP focused on climate-smart adaptation in Climate-Smart Villages (CSVs)

Playing with Burgers's equation

International audienceThe 1D Burgers equation is used as a toy model to mimick the resulting behaviour of numerical schemes when replacing a conservation law by a form which is equivalent for smooth solutions, such as the total energy by the internal energy balance in the Euler equations. If the initial Burgers equation is replaced by a balance equation for one of its entropies (the square of the unknown) and discretized by a standard scheme, the numerical solution converges, as expected, to a function which is not a weak solution to the initial problem. However, if we first add to Burgers' equation a diffusion term scaled by a small positive parameter ǫ before deriving the entropy balance (this yields a non conservative diffusion term in the resulting equation), and then choose ǫ and the discretization parameters adequately and let them tend to zero, we observe that we recover a convergence to the correct solution

Replacing Face-To-Face Classes by Synchronous Online Technologies: The HOU Experience

AbstractSince 2009, HOU has been providing live virtual classes for various distance learningprograms.This paper will provide an opportunity to look at the issues involved in the use of thesemultimedia-enabled delivery approaches, the technology behind them, the logistics involved,and to provide an HOU perspective of the experiences encountered.The goal of research was to provide a systematic methods to implement the highlyinteractive live session. The additional goals was to design the portable hardware and easy touse software toolset as well as easy to follow guidelines on how to propel the lectures fromthe conventional dull chalk and talk and to minimise the number of staff required to give thelectures.Through a combination of surveys and feedback from lecturers and students, we are ableto better understand the obstacles and to continuously improve on the effectiveness of theseinteractive delivery approaches