100,516 research outputs found
Construction of cospectral graphs, signed graphs and T-gain graphs via partial transpose
No full textIn the wake of Dutta and Adhikari, who in 2020 used partial transposition in order to get pairs of cospectral graphs, we investigate partial transposition for Hermitian complex matrices. This allows us to construct infinite pairs of complex unit gain graphs (or T-gain graphs) sharing either the spectrum of the adjacency matrix or even the spectrum of all the generalized adjacency matrices. This investigation also sheds new light on the classical case, producing examples that were still missing even for graphs. Partial transposition requires a block structure of the matrix: we interpreted it as if coming from a composition of T-gain digraphs. By proposing a suitable definition of rigidity specifically for T-gain digraphs, we then produce the first examples of pairs of non-isomorphic graphs, signed graphs and T-gain graphs obtained via partial transposition of matrices whose blocks form families of commuting normal matrices. In some cases, the non-isomorphic graphs detected in this way turned out to be hardly distinguishable, since they share the adjacency, the Laplacian and the signless Laplacian spectrum, together with many non-spectral graph invariants
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Hand verification for flexural strength of existing R.C. floors subject to degradation phenomena
No full textIn the present paper, a simplified model for hand verification of the flexural and shear strength of existing corroded T beams cast in place of lightened R.C. orthotropic slabs forming floors is presented and discussed. Diffused and pitting corrosion on steel bars, compressive concrete strength degradation and concrete bond strength degradation are included in the model. The original contribution of the paper is evaluation of the flexural and shear strength considering both the cases of strain compatibility and absence of compatibility and considering the main parameters governing the corrosion process. An arch-resistant model for the calculus of the flexural and shear strength of the beam was adopted in the absence of strain compatibility, while the plane section theory was adopted for the case of strain compatibility. No punching shear is considered. This approach is simple and can be applied on the basis of the experimental information available (carbonation test, chloride content, measurement of the pitting in the bar, gravimetric method for general corrosion) or by utilizing analytical expressions calibrated on the knowledge of the corrosion current intensity determined by linear polarization resistance measurement (LPR). The model was also verified against experimental results recently obtained by the authors
Spontaneous Interfacial Fragmentation of Inkjet Printed Oil Droplets and Their electrical characterization
No full textThis work presents the fabrication of femtoliter-scale oil droplets by inkjet printing based on a novel
mechanism for the spontaneous fragmentation at the interface with an immiscible water phase and
the electrical characterization of the resulting immersed “daughter” droplets. [1] In particular,
picoliter-scale fluorinated oil droplets impact on surfactant laden water phase at moderately high
Weber number (101), and are subjected to spreading and capillary instabilities at the water/air interface which ultimately lead to rupture in smaller sized droplets, according to reported models for macroscale droplets systems - [2] the emerging fragmentation results in “daughter” droplets having volumes of about 10-30 % with respect to the initial droplet volume. Remarkably, the picoliter scale downscaling leads to a novel surfactant-driven fragmentation due to the low Bond number (around 10-4-10-5), meaning that droplet immersion is dependent on surface tension forces and not on gravitational forces. In fact, the non-ionic Polyoxyethylene (20) sorbitan monolaurate was observed to permit the droplet immersion in the water phase only if spiked in the water phase at concentrations equal or higher than its critical micellar concentration (i.e. around 0.003% v/v). The resulting oil “daughter” droplets are characterized by a chip with integrated microelectrodes, permitting to extract number, velocities and diameter distribution (peaked at about 3 m) employing electrical impedance
measurements. In accordance with reported models, the electrical characterizations show that the
droplets have volumes in the femtoliter scale and are subjected to inertial focusing. [3] This work can
be considered an important advancement for understanding the effects of downscaling on
fragmentation phenomena at immiscible interfaces, leading to a knowledge platform for a tailored oil
droplets fabrication applicable for drug encapsulation, pharmaceutic preparations, and thin-film
wrapping around droplets. [4]
Bibliography
1. D. Spencer, F. Caselli, P. Bisegna and H. Morgan., Lab Chip, 2016, 16, 2467.
2. H. Lhuissier, C. Sun, A. Prosperetti, and D. Lohse, Phys. Rev. Lett., 2013, 110,
3. G. Arrabito, V. Errico, A. De Ninno, F. Cavaleri, V. Ferrara, B. Pignataro, and F.Caselli, Langmuir,
2019, 35, 4936.
4. D. Kumar, J. D. Paulsen, T. P. Russell, N. Menon, Science, 2018, 359, 775
Interfacial fragmentation and electrical characterization of inkjet printed dil droplets
No full textThis work presents a novel mechanism for the spontaneous fragmentation of picoliter-scale oil droplets at the interface with an immiscible water phase, and the electrical characterization of the resulting immersed “daughter” droplets by an electrical impedance chip (see Figure). [1] In particular, picoliter-scale fluorinated oil droplets are produced by inkjet printing at velocity higher than 5 m/s. Upon impact on the surfactant laden water phase at moderately high Weber number , i.e. around 10, the oil droplet is subjected to spreading and capillary instabilities at the water/air interface. These ultimately lead to its rupture in smaller sized droplets, according to
the reported models for macroscale droplets, [2] for which fragmentation results in “daughter” droplets with volumes reduced of about 10-30 %. Remarkably, the picoliter scale downscaling leads to a novel surfactant-driven fragmentation due to the low Bond number - around 10^(-4) -10^(-5), the droplet immersion mainly depending on surface tension forces. Indeed, the non-ionic Polyoxyethylene (20) sorbitan monolaurate was observed to permit the droplet immersion in the water phase only if spiked in the water phase at
concentrations equal or higher than its critical micellar concentration. The emerging “daughter” droplets are characterized by a microfluidic chip with integrated microelectrodes, permitting to extract number, velocities and diameter distribution (about 3 μm) by means of electrical impedance measurements. The electrical characterizations show that the droplets have volumes in the femtoliter scale and are not subjected to inertial focusing, owing to their small size. [3] This work can be considered an important advancement for understanding the effects of downscaling on fragmentation phenomena at immiscible interfaces, leading to a knowledge platform for a tailored oil droplets fabrication applicable for drug encapsulation, pharmaceutic preparations, and thin-film wrapping around droplets.[4]
Bibliography
1. D. Spencer, F. Caselli, P. Bisegna and H. Morgan., Lab Chip, 2016, 16, 2467.
2. H. Lhuissier, C. Sun, A. Prosperetti, and D. Lohse, Phys. Rev. Lett., 2013, 110,
3. G. Arrabito, V. Errico, A. De Ninno, F. Cavaleri, V. Ferrara, B. Pignataro, and F.Caselli, Langmuir, 2019, 35, 4936.
4. D. Kumar, J. D. Paulsen, T. P. Russell, N. Menon, Science, 2018, 359, 775
COMPRESSIVE BEHAVIOR OF LAMINATED GLASS COLUMNS
No full textThis paper examines the behavior in compression of glass columns having tee (T)
transverse cross-sections. The work highlights the issues recurring in the design of glass
columns in rapid diffusion in the transparent architecture such as: - flexural and torsional
buckling; - long-term effects and effects related to the temperature; - glued connections
between single panels. In the work expressions are given for the calculation of the loadcarrying
capacity of columns. The cases of full connection and absence of connection between
the panels are analyzed and discussed. The comparison between the analytical and the
experimental results highlights that in the case of glass columns with T cross-section failure
in the glued section and torsional buckling effects strongly limit the load carrying capacity of
members. In these cases the analytical prediction of load carrying capacity with analytical
expressions available in the literature allows good prediction and highlights that particular
care should be placed on the design of glued section
L'amministrazione regionale diretta
No full textIl contributo analizza i contorni e i caratteri dell'amministrazione regionale indiretta nell'ordinamento veneto
I procedimenti amministrativi
No full textIl contributo analizza le disposizioni dello Statuto regionale del Veneto in tema di procedimento amministrativo
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