A review and modern approach to LC ladder synthesis

Ultra low power circuits require robust and reliable operation despite the unavoidable use of low currents and the weak inversion transistor operation region. For analogue domain filtering doubly terminated LC ladder based filter topologies are thus highly desirable as they have very low sensitivities to component values: non-exact component values have a minimal effect on the realised transfer function. However, not all transfer functions are suitable for implementation via a LC ladder prototype, and even when the transfer function is suitable the synthesis procedure is not trivial. The modern circuit designer can thus benefit from an updated treatment of this synthesis procedure. This paper presents a methodology for the design of doubly terminated LC ladder structures making use of the symbolic maths engines in programs such as MATLAB and MAPLE. The methodology is explained through the detailed synthesis of an example 7th order bandpass filter transfer function for use in electroencephalogram (EEG) analysis. © 2012 by the authors; licensee MDPI, Basel, Switzerland.Published versio

Deep strong light-matter coupling in plasmonic nanoparticle crystals

In the regime of deep strong light–matter coupling, the coupling strength exceeds the transition energies of the material, fundamentally changing its properties; for example, the ground state of the system contains virtual photons and the internal electromagnetic field gets redistributed by photon self-interaction. So far, no electronic excitation of a material has shown such strong coupling to free-space photons. Here we show that three-dimensional crystals of plasmonic nanoparticles can realize deep strong coupling under ambient conditions, if the particles are ten times larger than the interparticle gaps. The experimental Rabi frequencies (1.9 to 3.3 electronvolts) of face-centred cubic crystals of gold nanoparticles with diameters between 25 and 60 nanometres exceed their plasmon energy by up to 180 per cent. We show that the continuum of photons and plasmons hybridizes into polaritons that violate the rotating-wave approximation. The coupling leads to a breakdown of the Purcell effect—the increase of radiative damping through light–matter coupling—and increases the radiative polariton lifetime. The results indicate that metallic and semiconducting nanoparticles can be used as building blocks for an entire class of materials with extreme light–matter interaction, which will find application in nonlinear optics, the search for cooperative effects and ground states, polariton chemistry and quantum technology

Theory of Plasmonic Nanostructures : Plasmon-Polaritons and Light-Induced Transport

In the first part, we investigate plasmon-polaritons in cubic metacrystals of spherical metallic nanoparticles. The triple degenerate surface plasmons on the nanoparticles couple to form collective plasmons through the Coulomb-dipole-dipole interaction. The collective plasmons extend over the entire metamaterial. By hybridization of the collective plasmons with photons, they form plasmon polaritons. The latter are hybrid light-matter eigenstates of the metamaterial. Using a formalism based on Hamiltonian operators, we derive general analytical expressions for the calculation of the plasmon and plasmon-polariton dispersions. This formalism includes retardation effects of the dipolar interaction and takes into account the dielectric properties of the nanoparticles and the surrounding material. Our model can also be applied to metamaterials made of two dielectrics if one of them has a polarization-based resonance with correspondingly high efficiency of Mie scattering. With this model, we predict polaritonic splittings in the range from NIR to Vis light. These splittings depend on the polarization, lattice symmetry, and direction of propagation. Comparing our predictions with conventional finite element simulation in the frequency domain provides an excellent agreement.In the second part, we investigate with time-dependent density functional theory (TDDFT) the electronic system responses of dimers of gold clusters coupled with vacuum, n-alkane dithiol (ADT) or oligo-p-phenylene-ethynylene dithiol (OPE) for various excitations. We obtain the response to periodic excitations in the frequency range from IR to UV light by Fourier transforming the response to a kick excitation. We concentrate on electric field enhancement (FE) and characterize the AC charge transport for molecules of different lengths and the corresponding distances of vacuum. For the vacuum structures, we reproduce the distance dependence of the FE between the gold tetrahedrons. The investigation of the induced charge density allows us to estimate the different transport mechanisms: Besides charge transfer, there is the mechanism of polarization of the coupling medium. The limiting frequency for the charge transfer through OPE molecules is below ħωWe obtain the time dependent response by using single-cycle pulses as excitation. We use a selection of structures used to investigate the periodic excitation. For sufficiently large amplitudes, we can describe the transferred charge in the structure with 22.9Å vacuum between the gold clusters by fitting and integrating the current in the center between the gold clusters with the Fowler-Nordheim expression. We perform further analysis with Simple Man’s Models (SMMs) with different quantum descriptions of the probability of electrons tunneling out of the gold clusters. The SMM, based on the Keldysh expression for the tunneling probability, describes the results for the vacuum or contact structures at the larger amplitudes. The Fowler-Nordheim based SMM reproduces the TDDFT results for large amplitudes; however, only for the structures with smaller distances between the gold clusters. The SMMs based on a single level transport model reproduce the simulation results for the structures with smaller distances between the gold clusters for all amplitudes. We find evidence of resonance behavior in the contact structure. For the gold clusters coupled with n-propane dithiol (ADT3), we find a three-level transport mechanism after an initial polarization of the molecule. The steps are 1. recombination of the charge carriers on both ends of the molecule,2. charging of both ends of the molecule3. recombination of the charge carriers in the middle of the molecule, similar to a p-n transition.This scheme explains1. the transport as a mixture of polarization and charge transfer in the periodic excitation of this structure, and2. the delay between the molecular current compared to the currents of the gold clusters.For the gold clusters coupled with ADT3, we investigate the dependence of the amount of transported charges on the CEP studied. We find the maximum of transferred charges for CEP between -80° and -50°. Most charge carriers follow the external electric field. On average, the fastest charge carriers only need 8as to pass the molecule.publishe

Effectiveness analysis of impact of small-size air targets by using AHEAD projectiles determining the correlation between ahead projectile and the target and determining the probability of impact

Dążenie do zwiększenia efektywności zwalczania celów powietrznych skutkuje wprowadzaniem nowych rodzajów amunicji przeciwlotniczej. Jednym z nich jest amunicja typu AHEAD. Charakteryzuje się ona tym, że cel atakowany jest chmurą lotek uwalnianych z pocisku w zaprogramowanym punkcie toru balistycznego. W niniejszym artykule analizowane są wzajemne relacje zachodzące pomiędzy celem i chmurą lotek w strefie ich możliwego spotkania. W tym zakresie oprócz omówienia poszczególnych związków, formułowane są również zalecenia dotyczące efektywnego prowadzenia ognia dla wymienionej amunicji. W wyniku rozważań teoretycznych opracowany został model do analizy obliczeniowej, w oparciu o który stosując metodę eksperymentu numerycznego wyznaczone zostało prawdopodobieństwo trafienia celu /w danym przypadku pocisku moździerzowego/. W zakończeniu zamieszczone zostały wnioski podsumowujące.In order to increase the effectiveness of fighting with air targets, there are introduced new types of antiaircraft ammunition. One of them is AHEAD type ammunition. It characterizes itself by the fact that the target is attacked by the cloud of ailerons freed from the projectile in a programmed point of ballistic course. In the article are analyzed mutual relations between the target and the cloud of ailerons in the area of their possible impact. As a result of theoretical deliberations there was developed the calculative analysis model. On the base of it by using numeric experiment method there was determined the probability of hitting the target (in this case: mortar projectile). In the final part there were presented summarizing conclusions

Strafe, Umwelt, Kommunikation eine empirische Erkundung personaler und sozialer Bedingungen fuer die individuelle Wirkung der gerichtlichen Verurteilung mit Hilfe soziologischer und soziometrischer Methoden

HUB(11) - 74 HB 0027 c / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman