Modeling aviation baggage screening security systems: a case study

Aviation security protects vital national interests, as well as passengers and aircraft. Key components of an aviation security system include baggage and passenger screening devices and operations. Determining how and where to assign (deploy) such devices can be quite challenging. Moreover, even after such systems are in place, it can be difficult to measure their effectiveness. This paper describes how discrete optimization models can be used to address these questions, based on three performance measures that quantify the effectiveness of airport baggage screening security device systems. These models are used to solve for optimal airport baggage screening security device deployments considering the number of passengers on a set of flights who have not been cleared using a security risk assessment system in use by the Federal Aviation Administration (i.e., passengers whose baggage is subjected to screening), the number of flights in this set, and the size of the aircraft for such flights. Several examples are provided to illustrate these results, including an example that uses data available from the Official Airline Guide.     

Gamma-irradiation-induced Ag/SiO2 composite films and their optical absorption properties

Small Ag particles or clusters dispersed mesoporous SiO₂ composite films were prepared by a new method: First the matrix SiO₂ films were prepared by sol-gel process combined with the dip-coating technique, then they were soaked in AgNO₃ solutions followed by irradiation of γ-ray at room temperature and in ambient pressure. The structures of these films were examined by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and optical absorption spectroscopy. It has been shown that the Ag particles grown within the porous SiO₂ films are very small, and they are isolated and dispersed from each other with very narrow size distributions. With increasing the soaking concentration and an additional annealing, an opposite peakshift effect of the surface plasmon resonance (SPR) was observed in the optical absorption measurements.     

Spectral properties of diesel fuel droplets

Absorption spectra of several types of diesel fuel are studied experimentally. Index of refraction of these fuels is calculated using subtractive Kramers-Krönig analysis. The ageing process of fuels is simulated by prolonged boiling. Radiative properties of diesel fuel droplets are calculated using the Mie theory and a simplified approach, based on approximations of absorption and scattering efficiency factors. It is pointed out that the accuracy of the simplified approach is sufficient for practical applications in the visible and infrared ranges, for various types of diesel fuel, and for droplet radii in the range from 5 to 50 μm. The monodisperse approximation is shown to be applicable for the analysis of infrared radiative properties of realistic polydisperse diesel fuel sprays.     

Polarizational Frequency-Selective Multipath Interference Devices for Millimetric- and Submillimetric-Wave Receivers

Variants are considered of palarizational frequency-selective multipath interference devices for millimetric- and submillimetric- wave receivers. Main expressions are presented that describe their characteristics. Advantages are pointed out of the devices as compared with Fabry-Perot interferometers when solving problems of received frequency-band shaping, heterodyne noise rejection, and signal- and heterodyne-radiation transfer to mixer.     

Modeling of a constant Voltage transformer

This paper presents a comprehensive nonlinear model of the controlled constant voltage transformer also known as the ferroresonant transformer. Saturation is a normal mode of operation for this device. This paper derives an equivalent electrical circuit that relates to the physical structure of a typical design. The level of detail includes winding resistances, continuously nonlinear magnetizing inductances, tapped windings, and leakage inductances. The paper describes methods to extract the winding resistances, leakage inductances, and hysteresis loops of the transformer and how to fit the latter into single-valued nonlinear functions. The paper compares computer simulation results of the model with those obtained analytically and experimentally. The results show that the derived circuit will be very useful for designers of the ferroresonant transformer, which is used in uninterruptible power supplies.     

Combined RLS-LMS initialization for per tone equalizers in DMT-receivers

In discrete multitone receivers, the classical equalizer structure consists of a (real) time domain equalizer (TEQ) combined with complex one-tap frequency domain equalizers. An alternative receiver is based on a per tone equalization (PTEQ), which optimizes the signal-to-noise ratio (SNR) on each tone separately and, hence, the total bitrate. In this paper, a new initialization scheme for the PTEQ is introduced, based on a combination of least mean squares (LMS) and recursive least squares (RLS) adaptive filtering. It is shown that the proposed method has only slightly slower convergence than full square-root RLS (SR-RLS) while complexity as well as memory cost are reduced considerably. Hence, in terms of complexity and convergence speed, the proposed algorithm is in between LMS and RLS.     

Low Temperature Physics at the Laboratoire National des Champs Magnétiques Pulsés in Toulouse

An overview over past and present activities and future developments at the Toulouse pulsed magnetic field facility is given, both as far as technical developments of the infrastructure, as well as low temperature physics performed at the LNCMP are concerned.     

Steady-state operation of a high-voltage multiresonant converter in a high-temperature environment

Often scientific instruments on exploratory satellites are used to collect cosmic particles. These instruments, such as the Faraday cup, require a high-voltage regulated power source. On the proposed solar probe satellite there will be instruments which will collect cosmic particles close to the sun. Naturally temperature effects on the voltage regulator are a concern. Specifically power dissipation within the regulator must stay within stringent guidelines. The high-voltage regulator circuit is a resonant flyback topology with a dissipative series switch whose on resistance controls the output voltage level. The extreme temperatures in space will change the inductance of the flyback transformer which will affect the output voltage. State space analysis techniques are used to determine how the value of the transformer inductance and capacitance in the flyback converter affects the output voltage and consequently the power dissipated by the transformer and the switch. The accuracy of the analysis is verified by comparing results with those obtained from an experimental circuit. The results can then be used to help the designer chose nominal capacitance and inductance values that will work over the temperature range of interest.     

Physico-chemical characterization of hybrid polymers obtained by 2-hydroxyethyl(methacrylate) and alkoxides of zirconium

Hybrid monolithic materials were prepared through polymerisation of 2-hydroxyethyl methacrylate (HEMA) mixed with zirconium alkoxides (Zr(OBuⁿ)₄, Zr(OPrⁿ)₄ and Zr(OEt)₄), modified by acetylacetonate groups. The molar ratio HEMA/Zr varied between 1 and 4. Thermo-Gravimetry coupled with Mass Spectroscopy (TG-MS) analyses, ¹³C MAS NMR and Dynamical Mechanical Thermal Analysys (DMTA) indicated the polymeric chains were interconnected by the inorganic component.The presence of zirconium alkoxides modified substantially the poly-HEMA properties. Glass transition temperature of hybrid materials derived from butoxy and propoxy was found in the range 50-80 °C, depending on the composition. The typical swelling of p-HEMA in the water, was suppressed by the presence of zirconium compounds. After immersion in distilled water, hybrid polymers showed an initial slight weight increase, followed by a small mass loss, which increases proportionally to the length of alkoxyl group (ethoxide(propoxide(butoxide) and reaches a constant value after about 40 days. The hybrids remained always rigid and transparent. Flexural modulus and strength of about 400-900 and 4-8 MPa were measured.     

Wavelength-tunable 40-GHz picosecond harmonically mode-locked fiber laser source

We demonstrate a novel 40-GHz mode-locked fiber laser that utilizes a single active device to provide both gain and mode-locking. The laser produces pulses as short as 2.2 ps, is tunable over a 27-nm band centered at 1553 nm, and exhibits long-term stability without cavity-length feedback control. The pulse train at 1556 nm was used in a 40-Gb/s transmission experiment over 45 km with a low 0.4-dB power penalty.