Anti-Personnel Land Mine Detection and Discrimination Using Acoustic Data

An acoustic-based land mine detection system was field-tested by the University of Mississippi with promising results. This system uses a Laser Doppler Vibrometer (LDV) to measure the velocity of the vibration at the surface of the soil induced by acoustic energy in various frequency bands. In this paper, automated methods for detecting and discriminating Anti-Personnel (AP) mines from clutter objects are presented. Pre-processing methods rely on nonlinear filters realized as Choquet integrals. These filters are robust to the non-Gaussian, impulse type noise in this type of data. Detection follows pre-processing and relies on adaptive thresholding over each frequency band and three-dimensional (3D) connected component analysis. Features are extracted from the 2D frequency slices of the 3D connected components. The features are adaptively aggregated over frequency and used for discriminant analysis. Experiments are performed using anti-personnel mines, clutter objects, and blank areas (background samples with no mines or clutter objects). The algorithm detects 92% of the mines for a wide range of parameters. For some threshold values, 100% of the mines are detected and 92% of the mines are classified as mines with no false alarms.     

Compressive behavior of large-scale square reinforced concrete columns confined with carbon fiber reinforced polymer jackets

Several experimental and analytical studies on the confinement effect and failure mechanisms of fiber reinforced polymer (FRP) wrapped columns have been conducted over recent years. Although typical axial members are large-scale square/rectangular reinforced concrete (RC) columns in practice, the majority of such studies have concentrated on the behavior of small-scale circular concrete specimens. The data available for square/rectangular columns are still limited. This paper reports the results of an experimental research program on the performance of large-scale square RC columns wrapped with carbon fiber reinforced polymer (CFRP) sheets. Attention is focused on the investigation of the total effect of longitudinal and transverse reinforcement and FRP jackets on the behavior of concentrically loaded columns. A total of 20 large-scale RC columns were fabricated and tested to failure under axial loading in the structural laboratory. Three types of columns were primarily considered: unwrapped; fully wrapped; and partially wrapped. Based on the test results of RC columns, existing experimental data and procedures in the literature are also evaluated. Furthermore, stress–strain curves of the columns are successfully predicted by the analytical approach previously proposed for FRP-confined concrete.     

Synthesis and swelling properties of new crosslinked polyorthocarbonates

Crosslinked polyorthocarbonates were synthesized by the condensation of tetraethyl orthocarbonate and hydroxyl functional monomers. The main goal of this study was to produce a solvent‐absorbent polymer with a high absorption capacity and to use these polymers for the removal of organic solvents from the environment and the recovery of these solvents. The synthesized polymers were characterized by Fourier transform infrared spectroscopy, solid‐state ¹³C‐NMR spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. All of the polymers (except Poly 1 and Poly 2 ) had a high and fast uptake ability for organic solvents, such as tetrahydrofuran, dichloromethane, benzene, and acetone. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Anaphylactoid reaction during hemodiafiltration on AN69 membrane in a patient with atypical hemolytic uremic syndrome: A pediatric case report

Reactions associated with hemodiafiltration can be life threatening if not recognized early in the course of dialysis. AN69 (acrylonitrile and sodium methallyl sulfonate copolymer) membrane-associated reactions during hemodialysis have been documented in adult patients receiving angiotensin converting enzyme inhibitors, which are thought to be triggered by the negative charge of the AN69 membrane. Here, we present a 5-month-old girl requiring continuous renal replacement therapy (CRRT) for acute kidney injury secondary to atypical hemolytic uremic syndrome who experienced acute cyanosis, angioedema, tachycardia, and impaired circulation during CRRT. After switching to a different type of hemofiltration membrane, her clinical findings improved and she was able to tolerate hemodialysis. We concluded that she had experienced an anaphylactoid reaction to the AN69 membrane. To our knowledge, this case is the first pediatric case report of AN69 membrane-associated anaphylactoid reaction.     

A practical approach for modeling FRP wrapped concrete columns

Fiber reinforced polymers (FRP) have gained rapid popularity in recent years as one of the strengthening techniques of structural concrete elements. Particularly, increase in the use of FRP composite materials for strengthening and retrofitting of reinforced concrete columns has urged the development of several approaches to determine their compressive strength. Although substantial experimental and analytical researches have been conducted to model and simulate the response of concrete confined with FRP jackets under concentric loading, there is still an apparent need for the detail analyses and efficient numerical models to further understand the stress–strain behavior and failure mechanisms of the confined concrete. In order to predict the compressive behavior of concrete even under high confinement pressures, this paper introduces new relations for calculation of the cohesion parameter of Drucker–Prager criterion in terms of cylindrical compressive strength only. These relations are developed from a parametric study of a large number of nonlinear finite element analyses (NLFFEA) of FRP wrapped concrete columns to account for the axial load level and the shape of the stress–strain curve. Incorporating a realistic one-parameter failure criterion of concrete, the failure cone of Drucker–Prager model is enforced to approximate and coincide with the whole compressive meridian of the criterion up to the analytically predicted point of the ultimate hydrostatic pressure in the analyses. Based on this failure cone, mainly seven different relations corresponding to the various levels of lateral pressure are proposed for the compressive meridian and the cohesion while keeping the internal friction angle as a constant value of 33°. The proposed approach is shown to fit quite well the experimental results of 42 specimens tested by eight different researchers, for various square and rectangular cross-sections under concentric loading.     

Thermal aspects of a circulating fluidized bed with air staging

In this study, effects of air staging on wall‐to‐bed heat transfer were investigated in a laboratory scale circulating fluidized bed (0.23 m ID, 7.6 m high). The bed was operated under ambient conditions with silica sand particles (d_p=89 µm, ρ_p=2650 kg m^?3). Two different designs of secondary air (SA) injectors were used for air staging: radial and tangential. Bed‐to‐wall heat transfer measurements were carried out at three elevations above the SA injection port. The results indicate that similar to non‐SA operation, the heat transfer with air staging depends strongly on the cross‐sectional average suspension density. Tangential secondary injection was found to increase the bed‐to‐wall heat transfer above the SA injection port significantly due to increased suspension density compared with non‐SA operation. Copyright © 2005 John Wiley & Sons, Ltd.     

Stress-Cracking of high density polyethylene in detergents

Correlations of the stress intensity factor, K_I, with crack speed, ?, have been obtained in a number of detergent solutions each having different detergent concentration. A constant crack speed region was observed in high density polyethylene. The K_I independent constant crack speed was found to vary linearly with detergent concentration. The viscosity of the detergent solution increases with concentration and hence this region is not controlled by the hydrodynamic properties of the environment in contrast with Williams' model. The K_I-? data were compared with existing models of crack propagation.     

Floating Immittance Function Simulator and Its Applications

A new floating immittance function simulator circuit is proposed using two different active elements, a dual-output second generation current conveyor (DO-CCII) and an operational transconductance amplifier (OTA). The presented circuit can realize a positive and negative floating inductor, capacitor and resistor depending on the passive component selection. Since the passive elements are all grounded, this circuit is suitable for fully integrated circuit design. The circuit does not require any component matching conditions, and it has a good sensitivity performance with respect to tracking errors. Moreover, the proposed positive and negative inductance, capacitor and resistor simulator can be tuned electronically by changing the biasing current of the OTA or can be controlled through the grounded resistor or capacitor. The proposed floating inductor simulator circuit is demonstrated by using a SPICE simulation for 0.35 μm TSMC CMOS technology. The proposed circuit consumes an average power of 1 mW using ±1.5 V supply voltages.     

Shifted-frequency internal equivalence

The shifted frequency internal equivalence (SFIE) theorem involving inhomogeneous regions is introduced and proven. For a lossless inhomogeneous region using a vector Green's theorem and potential formulation, it is shown that the frequency-domain electromagnetic field at frequency ω inside the region can be obtained using a set of equivalent volume and surface currents radiating in free space and at the different frequency ω₀. The equivalent currents thus obtained are functions of the two frequencies, electric- and magnetic-volume-type sources of the original problem, material parameters, and the original field phasors at ω, and they only exist inside the region and on its boundary. A direct application of this equivalence is that it can be used to construct an internal equivalence at a shifted frequency for electromagnetic scattering problems if data are needed in a band of frequency. ω₀ can be kept constant while the incident field frequency changes and, as a result, full computation of fields at each different frequency for volume-type equivalent sources can be avoided