Tuned liquid dampers for multi-storey structure: numerical simulation using a partitioned FSI algorithm and experimental validation

Wind-induced and earthquake-induced vibrations of structures such as super-tall towers and bridges can be efficaciously controlled by tuned liquid dampers (TLDs). This work presents a numerical simulation procedure to study the performance of TLDs–structure system through sigma (\( \sigma \))-transformation-based fluid–structure coupled solver. For this, a ‘C’-based computational code has been developed. The structural equations, which are coupled with the fluid equations in order to achieve the transfer of sloshing forces to structure for damping, are solved by the fourth-order Runge–Kutta method, while the fluid equations are solved using finite-difference-based sigma-transformed algorithm. Different iterative and error schemes are used to optimize the code for larger convergence rate and higher accuracy. For validation, a few experiments are conducted with a three-storey structure using TLDs arrangement. The present numerical results of response of TLD-installed structures match well with the experimental results. The minimum displacement of structure is observed when the resonance condition of the coupled system is achieved through proper tuning of TLDs. Since real-time excitations are random in nature, the performance study of TLDs under random excitation has also been carried out in which the Bretschneider spectrum is used to generate the random input wave.     

Low Cost Communication for High Speed Railway

Wireless Personal Communications - The demand for wireless communication has widely increased in high-speed railway (HSR). The people demand high capacity and efficient communication independent of...     

Carbon nanotubes for biomedical applications

Carbon nanotubes (CNTs) have many unique physical, mechanical, and electronic properties. These distinct properties may be exploited such that they can be used for numerous applications ranging from sensors and actuators to composites. As a result, in a very short duration, CNTs appear to have drawn the attention of both the industry and the academia. However, there are certain challenges that need proper attention before the CNT-based devices can be realized on a large scale in the commercial market. In this paper, we report the use of CNTs for biomedical applications. The paper describes the distinct physical, electronic, and mechanical properties of nanotubes. The basics of synthesis and purification of CNTs are also reviewed. The challenges associated with CNTs, which remain to be fully addressed for their maximum utilization for biomedical applications, are discussed.     

Studying ‘cost as information’ to account for construction improvements

Contractors throughout the construction supply chain develop and use cost information. By treating ‘cost as information’, insights are generated into how cost information is created and flows from work carried out to a client cost. A case study of a main contractor’s supply chain involved semi-structured interviews, workshops and document reviews. We considered whether contractors’ current costing practices used for the purpose of pricing and cost control could support decision-making about improvements through the supply chain. The results show that firms recognize that current costing practices do not provide a good representation of work carried out. Cost information that is useful in a narrative that seeks to improve site operations is either not created or hidden in layers of assumptions and lost as it does not cross the boundaries between organizations. This implies that the implementation of current practices of costing in building information modelling will not increase the effectiveness of modelling construction costs for the purpose of improvements. However, cost information that is useful in decision-making about improvements could be created. This could be achieved but requires a systemic change, where new representations of cost are tied to work processes used within more stable procurement relationships.     

Evaluation of the effects of engine parameters on performance and emissions of diesel engine operating with biodiesel blend

Diminishing resources, alarming pollution levels and escalating price associated with the application of diesel in compression ignition engine have forced scientific community throughout the world to conduct several experiments for the evaluation of biodiesel (BD) as a substitute for diesel. Due to difference in the physical and chemical properties of BD and diesel, the engine parameters such as compression ratio (CR), injection pressure (IP) and injection timing (IT) may not be optimum for BD, especially for higher blends. The present study is carried out with the aim to investigate the combined effect of CR, IP and IT on the performance and emission of a diesel engine widely used in agriculture sector in India, fuelled with B40 (40% BD and 60% diesel on a volume basis). Furthermore, this paper also aims to find the optimum engine parameters. A total of 27 sets of experiments were conducted for different combination of engine parameters and 162 sets of performance and emission data were recorded with varying load conditions. Adjustment of operating parameters was helpful to overcome the shortcoming of higher blend of BD (B40). The results demonstrated that higher CR (18:1) and IP (240 bar) along with advance IT (26° bTDC) is the best combination for a constant speed engine with brake power of 3.5 kW.     

Perturbation of an arctic soil microbial community by metal nanoparticles

Technological advances allowing routine nanoparticle (NP) manufacture have enabled their use in electronic equipment, foods, clothing and medical devices. Although some NPs have antibacterial activity, little is known about their environmental impact and there is no information on the influence of NPs on soil in the possibly vulnerable ecosystems of polar regions. The potential toxicity of 0.066% silver, copper or silica NPs on a high latitude (>78°N) soil was determined using community level physiological profiles (CLPP), fatty acid methyl ester (FAME) assays and DNA analysis, including sequencing and denaturing gradient gel electrophoresis (DGGE). The results of these different investigations were amalgamated in order to develop a community toxicity indicator, which revealed that of the three NPs examined, silver NPs could be classified as highly toxic to these arctic consortia. Subsequent culture-based studies confirmed that one of the community-identified plant-associating bacteria, Bradyrhizobium canariense, appeared to have a marked sensitivity to silver NPs. Thus, NP contamination of arctic soils particularly by silver NPs is a concern and procedures for mitigation and remediation of such pollution should be a priority for investigation.