Optimal piezo-electro-mechanical coupling to control plate vibrations

A new way of coupling electrical and mechanical waves, using piezoelectric effect, is presented here. Since the energy exchange between two systems supporting wave propagation is maximum when their evolution is governed by similar equations, hence, an optimal electromechanical coupling is obtained by designing an electric network which is "analog" to the mechanical structure to be controlled. In this paper, we exploit this idea to enhance the coupling, between a Kirchhoff-Love plate and one possible synthesis of its circuital analog, as obtained by means of a set of piezoelectric actuators uniformly distributed upon the plate. It is shown how this approach allows for an optimal energy exchange between the mechanic and the electric forms independent of the modal evolution of the structure. Moreover, we show how an efficient electric dissipation of the mechanical energy can be obtained adding dissipative elements in the electric network.Comment: 9 page

New insight into the Pleistocene deposits of Monte delle Piche, Rome, and remarks on the biochronology of Hippopotamus (Mammalia, Hippopotamidae) and Stephanorhinus etruscus (Mammalia, Rhinocerotidae) in Italy

Several large mammal assemblages have been collected in the Roman basin since the XIX century, but they usually lack any stratigraphic datum or details about the fossiliferous localities. In this work, the stratigraphic provenance of large mammal remains discovered at Monte delle Piche (Rome) is investigated. The systematic revision of these specimens allows the recording of the presence of Hippopotamus sp., Stephanorhinus sp. and Stephanorhinus etruscus. On the basis of micropalaeontological analysis performed on sediment sampled from the studied specimens and considering the stratigraphy of the area, two fossiliferous levels are recognised at Monte delle Piche. The remain of the hippopotamus was collected in fluvial gravels and sand deposits, in which the presence of Cyprideis is also recorded. This deposit is chronologically related to the latest Early-early Middle Pleistocene. Hippopotamus was present in Italy and Western Europe from the latest Villafranchian to MIS 4/3. The mandible of S. etruscus was collected in marine deposits along with abundant foraminifera and ostracods, which correlate with the late Early Pleistocene. Stephanorhinus etruscus occurred in Western Europe at the beginning of the Villafranchian, and it was documented until the end of the Villafranchian in Italy and until the Early-Middle Pleistocene transition in the Iberian Peninsula

Introduction to radar scattering application in remote sensing and diagnostics: Review

The manuscript reviews the current literature on scattering applications of RADAR (Radio Detecting And Ranging) in remote sensing and diagnostics. This paper gives prime features for a variety of RADAR applications ranging from forest and climate monitoring to weather forecast, sea status, planetary information, and mapping of natural disasters such as the ones caused by earthquakes. Both the fundamental parameters involved in scattering mechanisms of RADAR applications and the factors affecting RADAR performances are also discusse

Cloaking using the anisotropic multilayer sphere

We studied a Spherically Radially Anisotropic (SRA) multilayer sphere with an arbitrary number of layers. Within each layer permittivity components are different from each other in radial and tangential directions. Under the quasi-static approximation, we developed a more generalized mathematical model that can be used to calculate polarizability of the SRA multilayer sphere with any arbitrary number of layers. Moreover, the functionality of the SRA multilayer sphere as a cloak has been investigated. It has been shown that by choosing a suitable contrast between components of the permittivity, the SRA multilayer sphere can achieve threshold required for invisibility cloaking

Perencanaan Arrayed Waveguide Grating (AWG) Untuk Wavelength Division Multiplexing (WDM) Pada C-Band

Teknologi Arrayed Waveguide Grating (AWG), salah satu solusi membagi kanal menjadi sub kanal lebih kecil dengan mengatur selisih panjang array tetap. Dalam Makalah ini, dilakukan perencanaan desain parameter AWG beroperasi pada kanal C-Band (1530-1560 nm), untuk mendukung kebutuhan kanal WDM, baik coarse-WDM (CWDM), dense-WDM (CWDM) maupun very high density-WDM (VHDWDM). Perencanaan dilakukan lewat perhitungan teoritis dan menggunakan bantuan tool berupa WDM_Phasar.Perhitungan parameter AWG secara teoritis bertujuan menghasilkan parameter desain ideal, sementara lewat WDM_phasar dengan menambahkan batasan ukuran devais, crosstalk dan nonuniformity, diharapkan akan diperoleh parameter desain yang lebih realistis. Adapun parameter yang diamati meliputi besarnya orde difraksi (m), panjang free propagation range (FPR), perbedaan panjang array (ΔL), jumlah array (Narray), jumlah kanal I/O (Nmax) dan free spectral range (FSR).Dengan contoh spasi kanal 100 GHz pada C-band, dihasilkan parameter hitungan teoritis sebesar 1308,61 μm, 25,1698 μm, 43,7143, 108 buah, 27 kanal dan 21,211 nm, masing-masing untuk nilai FPR, ΔL, m, Narray, Nmax dan FSR. Sedangkan lewat bantuan WDM_Phasar dengan batasan ukuran devais (15000x9000 μm2), crosstalk (-35 dB) dan nonuniformity (0,5), menghasilkan parameter AWG 1197,347 μm(FSR), 23,764 μm(ΔL), 41(m), 56 (Narray), 16(Nmax) dan 11,2 nm(FSR). Semakin besar spasi kanal, jumlah bit yang bisa diangkut juga semakin banyak

Isoflavones and other compounds from the roots of Iris marsica I. Ricci E Colas. Collected from Majella National Park, Italy

In this study, a phytochemical analysis was performed, for the first time, on Iris marsica I. Ricci e Colas. In particular, the attention was focused on the constituents of the roots. Twenty-one compounds were isolated by column chromatography and were analyzed/identified by NMR spectroscopy and mass spectrometry. They all own chemotaxonomic, ethno-pharmacological and nutraceutical relevance which allowed us to provide a phytochemical rationale, for the correct botanical classification of this species, for the employment of its roots in folk medicine like for all the other species belonging to the Iris genus and, lastly, for their further uses as food with important healthy benefits. All of these parts were broadly discussed about within the text

About the use of generalized forms of derivatives in the study of electromagnetic problems

The use of non-local operators, defining Riemann–Liouville or Caputo derivatives, is a very useful tool to study problems involving non-conventional diffusion problems. The case of electric circuits, ruled by non-integer derivatives or capacitors with fractional dielectric permittivity, is a fairly natural frame of relevant applications. We use techniques, involving generalized exponential operators, to obtain suitable solutions for this type of problems and eventually discuss specific problems in applications

Dielectric permittivity of aqueous solutions of electrolytes probed by THz time-domain and FTIR spectroscopy

We have measured the dielectric permittivity of pure water and aqueous chlorides solutions in the range 0.2-1.5THz. We considered the relaxation spectral function as the weighted sum of two independent single-parameter Debye functions. Such an approach allowed to drastically reduce the number of the parameters used in the fit which we set only by physical considerations. The resulting functions allow to fit the experimental data for pure water and solutions of LiCl, KCl, NaCl, and CsCl and to predict the excess response on the high frequency side of the relaxation without “ad hoc” corrective terms

Finite-Size and Illumination Conditions Effects in All-Dielectric Metasurfaces

Dielectric metasurfaces have emerged as a promising alternative to their plasmonic counterparts due to lower ohmic losses, which hinder sensing applications and nonlinear frequency conversion, and their larger flexibility to shape the emission pattern in the visible regime. To date, the computational cost of full-wave numerical simulations has forced the exploitation of the Floquet theorem, which implies infinitely periodic structures, in designing such devices. In this work, we show the potential pitfalls of this approach when considering finite-size metasurfaces and beam-like illumination conditions, in contrast to the typical infinite plane-wave illumination compatible with the Floquet theorem