327,928 research outputs found
Second-order cone programming formulations for a class of problems in structural optimization
No full textThis paper provides efficient and easy to
implement formulations for two problems in structural
optimization as second-order cone programming
(SOCP) problems based on the minimum compliance
method and derived using the principle of complementary
energy. In truss optimization both single and
multiple loads (where we optimize the worst-case compliance)
are considered. By using a heuristic which is
based on the SOCP duality we can consider a simple
ground structure and add only the members which
improve the compliance of the structure. It is also
shown that thickness optimization is a problem similar
to truss optimization. Examples are given to illustrate
the method developed in this pape
Moral hazard and private monitoring.
No full text1This paper incorporates earlier work by Bhaskar [4] and unpublished notes by van Damme. We are grateful to Tilman Börgers, Dilip Mookherjee, Debraj Ray, an anonymous referee, an associate editor, and numerous seminar audiences for useful comments. The first author thanks the CentER for Economic Research (Tilburg) for its hospitality while some of this research was carried out.
The use and limitations of continuum modes for response calculations of cellular structures
No full textIn this paper, a method for the approximate calculations of response of cellular structures is presented. The method is based on the idea that for low-frequency modes, the cellular structures behave in a way similar as a continuum does. The range of validity of the method on the mode number scale is also examined. It is shown that the response is estimated very accurately from a reduced order model based on continuum modes for low-frequency vibration. The accuracy starts to deteriorate with the increase in the mode number. Beyond certain mode number, the improvement in accuracy due to the inclusion of additional continuum modes in the approxijmation shows a point of diminishing returns. illustrative examples are given
Tettilobus trishula Skejo, Bhaskar et Stermsek 2020, sp. n.
No full text<i>Tettilobus trishula</i> Skejo, Bhaskar et Stermšek sp. n. (morphology Figures 1, 2, habitat Figure 3) <p> <i>Tettilobus</i> sp.: Bhaskar et al. 2019: 3226, 3228 (reported from Eravikulam NP).</p> <p> <b>Type material.</b> 1♀ (Figures 1, 3) HOLOTYPE INDIA: Western Ghats—labels: 1 st (printed): Ind. Or. P. Castets, 2 nd (handwritten by Bolívar): <i>Potua</i> Bol. <i>suspecta</i> Bol., 3 rd (printed, published by París 1994): “especie” no publicada, 4 th (printed, red): Holotipo, 5 th (handwritten): <i>Tettilobus trishula</i> Skejo et Bhaskar, 6 th ‘ MNCN _Ent 195791’ (MNCN); 1♁ PARATYPE INDIA: Kerala: Eravikulam NP 2200 m a.s.l. (above sea level) N10 13’43.05” E077 05’09.39 ’ leg. Dhaneesh Bhaskar I.2018. (KFRI).</p> <p> <b>Type material depository</b>. The HOLOTYPE is deposited in MNCN, Madrid, Spain, the PARATYPE in KFRI, Kerala, India.</p> <p> <b>Type locality</b>. <b>Terra typica:</b> INDIA: Kerala: Western Ghats. <b>Locus</b> typicus restrictus: Eravikulam NP, mountainous rainforest at 2200 m a.s.l., N10 13’43.05” E077 05’09.39.</p> <p> <b>Habitat (Figure 3)</b>. From the original collection label (Ind. Or. P. Castets), the only thing we are sure of is that the place of the collection lies towards South India. According to the distribution of other species, Castets documented during the expeditions (Desutter-Grandcolas & Jaiswara 2012, Online catalogue of MNHN Paris type specimens) it has to be from the peninsular region (forested hills of Kerala and Tamil Nadu). The Narrower type locality is Eravikulam NP, where the paratype male was collected (Figure 3, Figure 11). The species inhabits dense rainforests of the Western Ghats. It can be found on tree trunks where it probably feeds on mosses and detritus. It is thus a bark dwelling, corticolous species, not a leaf-litter species like <i>Deltonotus subcucullatus</i> and <i>D. gibbiceps</i></p> <p> <b>Derivatio nominis</b>: In Hindu mythology and epics like Mahabharata and Ramayana, <i>trishula,</i> with a trident known as <i>trishulank</i>, originally from Sanskrit, is a three-pronged spear that Lord Shiva used as his sacred weapon to fight off evil. Each tooth of the trishula is called a <i>guna</i> in Samkhya philosophy. Three <i>gunas</i> are in this new species made of the highly compressed median carina and elevated curved external (large trishula) and internal (small trishula) lateral carinae of the pronotal apex.</p> <p> <b>Specific diagnosis.</b> Nanopronotal, small and wingless species (body length from the apex of fastigium to the top of the ovipositor 7.5 mm); vertex, in frontal view, depressed; antennal grooves situated below the lower margin of the compound eyes; scutellum as wide as a single antennal groove; frontal costa bifurcation located on the level of the lower margins of the compound eyes; frontal costa above bifurcation long; median carina of the vertex, lateral carinae of the vertex and transverse carinae projected as equally high horns; FM small, PM+MM1 compressed and highly elevated, MML1 and MML2 strong; VL projected downwards-outwards with rounded apex; strongly incurved external lateral carinae; internal lateral carinae forming with median carina acute upwards directed structure reminding of <i>trishula</i>; all femora armed with sharp teeth; pronotum not covering the whole abdomen; visible part of the abdomen armed. The species can easily be distinguished from <i>T. prashadi</i> and <i>T. pelops</i> by the lack of ventrolateral spines, but also by the morphology of the head and pronotal discus.</p>Published as part of <i>Bhaskar, Dhaneesh, Stermšek, Sara, Easa, P. S., Franjević, Damjan & Skejo, Josip, 2020, Wide-nosed pygmy grasshoppers (Cladonotinae: Cladonotini, Xerophyllini) of India and Sri Lanka: catalogue with an identification key and description of a new species of the genus Tettilobus, pp. 474-500 in Zootaxa 4894 (3)</i> on page 476, DOI: 10.11646/zootaxa.4894.3.12, <a href="http://zenodo.org/record/4315827">http://zenodo.org/record/4315827</a>
The effective Poisson ratio of random cellular matter having bending dominated architecture
No full textWe argue that the effective Poisson ratio of cellular and porous solids is independent
of the material of the solid phase, if the mechanism of the cell wall deformation is dominated
by beam bending —thus rendering it to be a purely kinematic quantity. Introducing a kinematic
simplification and requiring statistical isotropy, we prove a result of remarkable generality that the effective Poisson ratio of irregular planar structures equals 1 for all bending dominated random architectures. We then explore a deeper connection of this behavior with area-preserving deformation of planar closed elastic cells. We show that thin sheets and films made of such
microstructured material afford physical realizations of the two-dimensional analogue of incompressible matter.We term such non-stretchable sheet material as well as deformations as isoektasic
The applicability of the effective medium theory to the dynamics of cellular beams
No full textThe applicability and the limitations of the effective medium assumption for the dynamics of cellular beams are studied. Beams made of uniform triangular and regular hexagonal cells are analysed. The natural frequencies and modal distributions are calculated using the detailed finite element model of the cellular networks are compared with those predicted based on equivalent homogenous media of the same overall size and shape. It is observed that, for low mode number, a cellular beam behaves as a continuum, provided the cell size is significantly smaller than the external dimensions of the beam. Due to different deformation mechanisms triangular cells show frequencies independent of area fraction whereas hexagonal cells show this dependence clearly. As the wavelength starts to become of the order of the heterogeneity, the continuum behaviour begins to break down. With the increase in mode number, cellular beams exhibit inherent flexibility with a progressive increase in their modal densities as compared to those of a homogeneous continuum. The modal density increases further when the cell walls start to resonate. During resonance, an abrupt rise in the modal density is observed for the triangular cellsas the cell walls start deforming in the flexural mode instead of the axial mode. In contrast, for hexagonal cells, the predominant mode of cell wall deformationis always flexural
Dr Ashish Bhaskar
No full text<p>Dr Bhaskar's research interests include:</p>
<ul>
<li>Transport data analytics</li>
<li>Predictive modelling (traffic state estimation and prediction)</li>
<li>Traffic flow theory (emerging connected and automated vehicles; non-lane/quasi lane discipline)</li>
<li>Multimodal demand modelling (exploting advance traffic and transit data)</li>
<li>Real time multimodal (car and transit) operations and control</li>
<li>Traffic simulation</li>
<li>Benchmarking</li>
</ul>
Taussky' s theorem, symmetrizability and modal analysis revisited
No full textThis paper is concerned with symmetrization and diagonalization of real matrices and their implications for the dynamics of linear, second-order systems governed by equations of motion having asymmetric coefficient matrices. Results in the light of Taussky's theorem are presented. The connection of the symmetrizers with the eigenvalue problem is brought out. An alternative proof of Taussky's theorem for real matrices is presented. Diagonalization of two real symmetric (but not necessarily positive-definite) matrices is discussed in the context of undamped non-gyroscopic systems. A commutator of two matrices with respect to a given third matrix is defined; this commutator is found to play an interesting role in deciding simultaneous diagonalizability of two or three matrices. Errors in a few previously known results are brought out. Pseudo-conservative systems are studied and their connection with the so-called 'symmetrizable systems' is critically examined. Results for modal analysis of general non-conservative systems are presented. Illustrative examples are given
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