Behaviour of steel end plate bolted beam-to-column joints

This paper presents a numerical investigation into moment-rotation behaviour of extended, flush, and partial depth end-plate joints. Two types of steel beam-to-column joints are modelled: I-beam (IPE) to H-column (HEB) and PFC-beam (UPE) to SHS-column. The joints are designed as a single cantilever beam-to-column joint configuration. The connection details are in accordance with Eurocode 3 part 1-8 and SCI guides P358 (Simple joints) and P398 (Moment joints). Three-dimensional finite element modelling of the joints is car-ried out using ABAQUS. The numerical results are validated against experiments. Both material and geo-metric nonlinearities are considered. All joints are classified according to their stiffness as per Eurocode 3. The failure modes of different joint configurations are determined and compared with the experiments. The key contribution of this paper comes from stiffness analysis of the joints, characterisation of the joints as per EC3 and modelling nonlinear behaviour of the joints

AMCTD: Adaptive Mobility of Courier nodes in Threshold-optimized DBR Protocol for Underwater Wireless Sensor Networks

In dense underwater sensor networks (UWSN), the major confronts are high error probability, incessant variation in topology of sensor nodes, and much energy consumption for data transmission. However, there are some remarkable applications of UWSN such as management of seabed and oil reservoirs, exploration of deep sea situation and prevention of aqueous disasters. In order to accomplish these applications, ignorance of the limitations of acoustic communications such as high delay and low bandwidth is not feasible. In this paper, we propose Adaptive mobility of Courier nodes in Threshold-optimized Depth-based routing (AMCTD), exploring the proficient amendments in depth threshold and implementing the optimal weight function to achieve longer network lifetime. We segregate our scheme in 3 major phases of weight updating, depth threshold variation and adaptive mobility of courier nodes. During data forwarding, we provide the framework for alterations in threshold to cope with the sparse condition of network. We ultimately perform detailed simulations to scrutinize the performance of our proposed scheme and its comparison with other two notable routing protocols in term of network lifetime and other essential parameters. The simulations results verify that our scheme performs better than the other techniques and near to optimal in the field of UWSN.Comment: 8th International Conference on Broadband and Wireless Computing, Communication and Applications (BWCCA'13), Compiegne, Franc

Harnessing Intellectual Resources in a Collaborative Context to Create Value

The value of electronic collaboration has arisen as successful organisations recognize that they need to convert their intellectual resources into customized services. The shift from personal computing to interpersonal or collaborative computing has given rise to ways of working that may bring about better and more effective use of intellectual resources. Current efforts in managing knowledge have concentrated on producing; sharing and storing knowledge while business problems require the combined use of these intellectual resources to enable organisations to provide innovative and customized services. In this chapter the collaborative context is developed using a model for electronic collaboration through the use of which organisations may mobilse collaborative technologies and intellectual resources towards achieving joint effect.electronic collaboration;value creation;collaborative computing;knowledge management and intellectual resources

Cyclic Response of Bolted and Hybrid Pultruded FRP Beam-Column Joints between I-Shaped Sections

This paper presents cyclic behaviour of bolted and hybrid–combined bolted and bonded fibre re-inforced polymer (FRP) beam-to-column joints between I-shaped members using steel and FRP cleats. Five full-scale cyclic tests are carried out to study moment-rotation behaviour, cyclic re-sponse, and failure patterns. The test parameters include position of cleat (flange or combined web and flange), fastening method (bolting or hybrid–combining bolting and bonding) and cleat ma-terial (steel or FRP). First two tests had bolted and hybrid joints with steel flange and web double angles. Next two tests had the same joint detailing but with no web cleats. Last test used bolted joint only with FRP web and flange cleats. Three failure modes were observed: shear-out failure of the beam’s bolted zone, adhesive debonding with shear-out failure and delamination cracking. Cyclic performance of the joints was assessed by hysteresis moment-rotation curves and accumulated dissipated energy. Hybrid joints showed the best overall cyclic performance with accumulated dissipated energy about 75% higher than the bolted joints. Bolted joints with FRP cleats exhibited the worst cyclic performance. Flange cleated joints showed similar performance to web and flange cleated joints

Bolted and hybrid beam-column joints between I-shaped FRP profiles Chapter Bolted and hybrid beam-column joints between I-shaped FRP profiles

Presented are test results from five full-scale pultruded FRP beam-to-column joints subjected to cyclic load-ing. The parameters include cleat position, connection method and cleat material. The joints’ behaviour is assessed through hysteresis moment rotation loops, accumulated dissipated energy and failure patterns. The hybrid joints with steel cleats showed the best overall cyclic performance with accumulated dissipated ener-gy 75% higher than the bolted joint. The bolted joint with FRP cleats exhibited the lowest dissipated energy, four times lower than the joint with steel cleats. The cyclic performance of web and flange cleated joint was same as flange cleated joint. Three failure patterns were noticed, namely shear-out failure of the beam’s bolted region (bolted joint with steel cleats), adhesive debonding followed by shear-out failure (hybrid joint with steel cleats) and delamination cracking (bolted joint with FRP cleats)

Dynamics of Tunneling Centers in Metallic Systems

Dynamics of tunneling centers (TC) in metallic systems is studied, using the technique of bosonization. The interaction of the TC with the conduction electrons of the metal involves two processes, namely, the screening of the TC by electrons, and the so-called electron assisted tunneling. The presence of the latter process leads to a different form of the renormalized tunneling frequency of the TC, and the tunneling motion is damped with a temperature dependent relaxation rate. As the temperature is lowered, the relaxation rate per temperature shows a steep rise as opposed to that in the absence of electron assisted process. It is expected that this behavior should be observed at very low temperatures in a careful experiment. The present work thus tries to go beyond the existing work on the {\it dynamics} of a two-level system in metals, by treating the electron assisted process.Comment: REVTeX twocolumn format, 5 pages, two PostScript figures available on request. Preprint # : imsc 94/3

Maternal risk factors associated with low birth weight in Karachi: A case-control study

To evaluate maternal risk factors associated with low birth weight (LBW) among women aged 15-35 years, we carried out a hospital-based, case-control study on 262 cases (mothers of neonates weighing \u3c or = 2.5 kg) and 262 controls (mothers of neonates weighing \u3e 2.5 kg). Odds of delivering a low-birth-weight baby decreased with increase in maternal haemoglobin [odds ratio (OR): 0.701; 95% confidence interval (CI): 0.62-0.79]. Odds were greater among mothers not using iron supplements during pregnancy (OR: 2.88; 95% CI: 1.83-4.54). Mothers of LBW babies had lower haemoglobin levels before delivery