A car-following collision prevention control device based on the cascaded fuzzy inference system

A car-following collision prevention control device based on the cascaded fuzzy inference system (CFIS), consisting of a velocity fuzzy controller and an acceleration fuzzy controller, to nonlinearly control car acceleration or deceleration rate is proposed. The distance and speed relative to the car in front are measured using spread spectrum radar and applied to the collision prevention control device. The output acceleration or deceleration rate obtained from the CFIS car-following collision prevention system is based on the characteristics of the vehicle. The simulation results demonstrate that the presented CFIS control device can solve the oscillation problems for final relative distance between the lead vehicle (LV) and following vehicle (FV) and relative speed. When the LV applies the brake suddenly or a stationary obstacle appears in front of vehicle moving at high speed on the roadway, the CFIS control device can safely avoid a collision. The CFIS car-following collision prevention control device proposed in this paper can provide a safe, reasonable and comfortable drive.     

Spread measures and their relation to aggregation functions

The theory of aggregation most often deals with measures of central tendency. However, sometimes a very different kind of a numeric vector’s synthesis into a single number is required. In this paper we introduce a class of mathematical functions which aim to measure spread or scatter of one-dimensional quantitative data. The proposed definition serves as a common, abstract framework for measures of absolute spread known from statistics, exploratory data analysis and data mining, e.g. the sample variance, standard deviation, range, interquartile range (IQR), median absolute deviation (MAD), etc. Additionally, we develop new measures of experts’ opinions diversity or consensus in group decision making problems. We investigate some properties of spread measures, show how are they related to aggregation functions, and indicate their new potentially fruitful application areas.     

Subregular planes admitting elations

New classes of subregular planes are constructed that admit elation groups or Baer groups of order > 2. Further, we construct a variety of large dimension translation planes admitting many elations.     

An efficient spread spectrum pulse position modulation scheme for point-to-point underwater acoustic communication

The underwater acoustic channel is a complicated and time-varying multipath channel, and many equalization algorithms have been researched and developed to overcome the difficulties for underwater acoustic communication. Unfortunately, many algorithms are computational intensive and prone to lose convergence due to their sensitiveness to different channel configurations. In this paper, a pulse position modulation (PPM) scheme is proposed, and it uses two M-sequences of low cross-correlation to transfer information, which are modulated on two orthogonal carriers. One is used as a reference sequence, and the other is shifted relative to the reference. Information is carried by the starting time difference between the two sequences in each symbol. Comparing with conventional direct-sequence spread spectrum technique, the proposed scheme is more spectral efficient. Two receiver designs are given, one takes advantages of M-sequences’ auto-correlation properties, and the other is motivated by passive phase conjugation (PPC) to take advantages of the channel. Combined with M-sequence, PPC performance is augmented without a receiving array to cover the water column, and it is far less complex than adaptive equalizers for receivers. Results from lake field trials are analyzed, and they verify potential applications of this PPM scheme.     

Syntheses and properties of novel non-ionic fluorinated multichains “star-like” surfactants

A series of star-like nonionic surfactants (with two hydrophobic and two hydrophilic chains) with different lengths of hydrophilic and hydrophobic arms were synthesised on the basis of pyromellitic acid dianhydride. The hydrophilic arms were formed by polyoxyethylene and hydrophobic ones either by perfluoro- or by alkyl chains. The adsorption monolayers (Gibbs monolayers) were studied by surface pressure (π) measurements as a function of time for different surfactant concentrations. For the spread monolayers (Langmuir monolayers), the measurements of the surface pressure (π) versus the molecular area (A) as well as the relaxation measurements of the area (A) as a function of time at constant surface pressure were performed. The comparison between the characteristic parameters of two types of monolayers was made in order to understand the effect of the preparation conditions on the structure of these monolayers.It was found that decreasing the fluoroalkyl chain length induced a systematical decrease in the stability of Langmuir monolayers, which is manifested as the Marangoni-Gibbs viscoelasticity of the monolayers. For the surfactants, which have a large number of oxyethylene groups, adsorption at the air/water interface from the bulk solution required extremely long times to reach equilibrium due to the diffusion from the solution and to the conformational rearrangements at the interface. The observation of a hysteresis in the compression/decompression curves for these compounds is explained by the presence of the residual organic solvent molecules absorbed by oxyethylenic chains. A novel model describing the kinetics of desorption or rearrangement of molecules during the lateral compression was suggested, allowing the estimation of both characteristic time of this process and areas per molecule at the equilibrium from the relaxation curves A(t).     

Impact of bulk and surface properties of some biocompatible hydrophobic polymers on the stability of methylene chloride-in-water mini-emulsions used to prepare nanoparticles by emulsification-solvent evaporation

The emulsifying and stabilizing ability of several hydrophobic (insoluble in water and soluble in volatile organic solvents) polymers, such as Eudragit RL, Eudragit RS, PLGA, PCL, and their mixtures, with regard to the methylene chloride (MC)-in-water mini-emulsions, has been compared to the viscosity of MC solutions and to the properties of adsorption and spread monolayers of these polymers.

Eudragits RS and RL contain 2.5 and 5 mol% of pendent cationic trimethylammonium (TMA) groups per 164 g/mol segments, whereas PLGA and PCL contain 1 and 2 polar carbonyl groups per 130 and 114 g/mol, respectively. The electrostatic attraction between the dipoles, formed by TMA groups and the condensed counter ions in the MC solutions, leads to the contraction of macromolecular coils of Eudragits, whereas the PLGA and PCL macromolecules, interacting by low polar carbonyl groups (with dipole moment μ = 2.7 D) retain more extended conformation in MC. This explains why the characteristic viscosities [η] of MC solutions are much lower for the former polymers (0.1 dL/g) with regard to PLGA and PCL solutions whose [η] is equal to 0.3 and 0.6 dL/g, respectively.

The ionization of TMA groups in contact with the water phase leads to the irreversible adsorption of Eudragits at the MC/water interface and to high decrease of the interfacial tension γ (down to 4 mN/m for the 5% MC solutions). Whereas PLGA and PCL possessing low polar carbonyl groups adsorb poorly at the MC/water interface exhibiting γ  28 mN/m. Higher stability of spread monolayers of Eudragits (π*  40 mN/m) with regard to PLGA and PCL (π* < 20 mN/m) correlates well with higher interfacial activity of the former with regard to the later. The higher surface potential ΔV of Eudragits (0.9 V) with regard to PLGA (0.3 V) and PCL (0.4 V) is explained by the formation of electric double layer (DL) by the former, whereas the later contribute to the ΔV only by cumulative dipole moments of carbonyl groups. The experimental values of surface potentials correlate well with the Gouy–Chapman model of the DL and the Helmholtz model of the monolayer.

The ensemble of experimental results leads to the conclusion that higher emulsifying and stabilizing ability of Eudragits with regard to PLGA and PCL is due to higher adsorption activity of the former which form the corona of polymeric chains with ionized TMA groups around the droplets. It can be postulated that Eudragit polymers have good surface active properties which may allow manufacturing of biocompatible nanoparticles by emulsification–solvent evaporation method without surfactants.     

Capacity of wander and spread beams in log-normal distribution non-Kolmogorov turbulence optical links

We model the average channel capacity of optical wireless communication systems in weak turbulence horizontal channels, using the log-normal distribution models. The effects of beam wander and spread, pointing errors, turbulence inner scale, turbulence outer scale and the spectral index of non-Kolmogorov turbulence on system's performance are included. The model can evaluate the influence of the atmospheric turbulence conditions in the performance of a ground-to-train optical wireless communication system.     

The total Position Spread in mixed‐valence compounds: A study on the model system

The behavior of the Total Position Spread (TPS) tensor, which is the second moment cumulant of the total position operator, is investigated in the case of a mixed‐valence model system. The system consists of two H₂ molecules placed at a distance D. If D is larger than about 4 bohr, the singly ionized system shows a mixed‐valence character. It is shown that the magnitude of the TPS has a strong peak in the region of the avoided crossing. We believe that the TPS can be a powerful tool to characterize the behavior of the electrons in realistic mixed‐valence compounds. © 2014 Wiley Periodicals, Inc.     

The properties of a GaAs-GaAlAs traveling-wave laser amplifier

In this paper, the use of an optical fiber-based fixed infrastructure for code division multiple access (CDMA) mobile networks is considered. One of the major problems associated with optical subcarrier multiplexing (SCM) is the nonlinearity of the laser diodes (LD). The LD is modeled by a memoryless nonlinearity, and the effect of the nonlinearity on the SCM transmission of CDMA signals is evaluated. The behavior departs significantly from what happens in frequency division multiple access (FDMA), and depends critically on the nonlinearity being compressing or expanding. In the former case, significant performance degradation may occur, whereas for the latter this is usually not dramatic. When compared against FDMA, the major advantage of CDMA comes from the tight power control function that must be built in such systems, which means that situations of a weak signal corrupted by strong signals do not occur, unlike what happens in FDMA.