Predicting structural and statistical features of wall turbulence

The majority of practical flows, particularly those flows in applications of importance to transport, distribution and climate, are turbulent and as a result experience complex three-dimensional motion with increased drag comparedwith the smoother, laminar condition. In this study, we describe the development of a simple model that predicts important structural and scaling features of wall turbulence. We show that a simple linear superposition of modes derived from a forcing-response analysis of the Navier-Stokes equations can be used to reconcile certain key statistical and structural descriptions of wall turbulence. The computationally cheap approach explains and predicts vortical structures and velocity statistics of turbulent flows that have previously been identified only in experiments or by direct numerical simulation. In particular, we propose an economical explanation for the meandering appearance of very large scale motions observed in turbulent pipe flow, and likewise demonstrate that hairpin vortices are predicted by the model. This new capability has clear implications for modeling, simulation and control of a ubiquitous class of wall flows

TMS320C6713DSP IMPLEMENTATION OF PULSE SHAPING FILTER

One of the most challenging issues facing deployment of 3G technology is how to make the network architectures compatible with each other. New signaling techniques are being designed specially to enhance today’s networks, deliver unprecedented functionality for 3G, and successfully derive the future generation of wireless systems, thus delivering immediate and long term benefits to subscribers. With the architecture of each generation of wireless devices addressed in the development of advance technologies, subscribers can easily evolve their systems without additional network modification, significantly reducing cost and implementing time. The next generation systems based on the DS-CDMA, FDMA/TDMA and GSM concepts are projected to provide transmitting high speed data, video and multimedia traffic for both indoor and outdoor systems, new technologies like Wideband Code Division Multiple Access (WCDMA), already in service, are providing users with high data rate services options like they have never experienced previously. The present paper deals with DSP Implementation of pulse shaping filter for wireless communication

Scaling and interaction of self-similar modes in models of high-Reynolds number wall turbulence

Previous work has established the usefulness of the resolvent operator that maps the terms nonlinear in the turbulent fluctuations to the fluctuations themselves. Further work has described the selfsimilarity of the resolvent arising from that of the mean velocity profile. The orthogonal modes provided by the resolvent analysis describe the wall-normal coherence of the motions and inherit that self-similarity. In this contribution, we present the implications of this similarity for the nonlinear interaction between modes with different scales and wall-normal locations. By considering the nonlinear interactions between modes, it is shown that much of the turbulence scaling behaviour in the logarithmic region can be determined from a single arbitrarily chosen reference plane. Thus, the geometric scaling of the modes is impressed upon the nonlinear interaction between modes. Implications of these observations on the self-sustaining mechanisms of wall turbulence,modelling and simulation are outlined

Passivity-Based Output-Feedback Control of Turbulent Channel Flow

This paper describes a robust linear time-invariant output-feedback control strategy to reduce turbulent fluctuations, and therefore skin-friction drag, in wall-bounded turbulent fluid flows, that nonetheless gives performance guarantees in the nonlinear turbulent regime. The novel strategy is effective in reducing the supply of available energy to feed the turbulent fluctuations, expressed as reducing a bound on the supply rate to a quadratic storage function. The nonlinearity present in the equations that govern the dynamics of the flow is known to be passive and can be considered as a feedback forcing to the linearised dynamics (a Lur’e decomposition). Therefore, one is only required to control the linear dynamics in order to make the system close to passive. The ten most energy-producing spatial modes of a turbulent channel flow were identified. Passivity-based controllers were then generated to control these modes. The controllers require measurements of streamwise and spanwise wall-shear stress, and they actuate via wall transpiration. Nonlinear direct numerical simulations demonstrated that these controllers were capable of significantly reducing the turbulent energy and skin-friction drag of the flow

Sezary syndrome in a young retropositive male: A rare case report

Sezary syndrome, a rare disease, is the leukemic counterpart of mycosis fungoides accounting for less than 5% of cutaneous lymphomas.Very few case reports have been published of Sezary syndrome/mycosis fungoides presenting in young male and with coexisting HIV.We present a case of a 23-year-old retropositive male presenting with Sezary syndrome which is very rare. The present case highlightsthe fact that Sezary syndrome can rarely present in young and retropositive patients. It should be kept in differential diagnosis if apatient presents with erythroderma, generalized lymphadenopathy and characteristic peripheral smear findings. A multimodal approachinvolving flow cytometry, skin biopsy and fine needle aspiration cytology (FNAC) is required for arriving at a definite diagnosis

POTENTIAL USE OF GRAFT COPOLYMERS OF MERCERIZED FLAX AS FILLER IN POLYSTYRENE COMPOSITE MATERIALS

Graft copolymerization of binary vinyl monomers onto mercerized flax fiber was carried out for the enhancement of mechanical properties of polystyrene composites. Binary vinyl monomer mixture of AA+AN has been found to show maximum grafting (33.55%) onto mercerized flax. Graft copolymers thus synthesized were characterized with FT-IR spectroscopy, SEM, and TGA techniques. Mercerized flax (MF) showed maximum thermal stability in comparison to graft copolymers. It has been found that polystyrene composites reinforced with graft copolymers showed improvement in mechanical properties such as wear resistance, compressive strength, and tensile strength

Plant invasions along roads: a case study from central highlands, India

Road sides provide suitable conditions for the establishment and growth of non-native species. The phenomenon of non-native species spread through roads has further increased due to rapid anthropogenic developments. Here we intend to investigate the status of native and nonnative species and how the species richness and diversity change in a perpendicular road transect across the three different road use types in the central highlands of India. Presence of 55 nonnative species was recorded, of the total 71 species along the road sides. Non-native species richness significantly increased with increasing road use type. Although, the species diversity significantly decreased from road verges to the forest interior in all the road use types. Indicating the role of non-native propagule spread through the roads into the interior forest landscapes. The study gives a management implication, to restrict the non-native species spread from the road sides to the forest interior, irrespective of road use types.Centre of Excellence for Invasion Biolog

Physiotherapists’ experiences with a four-week mindfulness-based stress reduction program

Objective: The study sought to gather the perceptions and experiences of a group of physiotherapists who took part in mindfulness-based stress reduction program (MBSR). Methods: Semi-structured interviews were conducted with eight physiotherapists who took part in a four-week formal and self-directed mindfulness meditation program. The data collected were analysed by implementing a thematic analysis. Results: Themes were identified in relation to perceived health benefits (stress reduction and increased attentiveness), the perceived impact of the MBSR on their professional practice and the perceived difficulties in practicing mindfulness. Conclusion: The data from this study offer qualitative evidence that mindfulness practise can become an important element in a physiotherapists’ stress reduction toolkit, by helping them deal with the challenges of their professional practise. The main difficulties encountered with the program were related to the feelings of sleepiness that MBSR induced in them in the beginning. The participants also reported that the long duration of the sessions was another obstacle, suggesting that a brief form of meditation would be preferable and more convenient