An EM‐based adaptive multiple target tracking filter

Tracking targets of interest is one of the major research areas in radar surveillance systems. We formulate the problem as incomplete data estimation and apply EM to the MAP estimate. The resulting filter has a recursive structure analogous to the Kalman filter. The advantage is that the measurement‐update deals with multiple measurements in parallel and the parameter‐update estimates the system parameters on the fly. Experiments tracking separate targets in parallel show that tracking maintenance ratio of the proposed system is better than that of NNF and RMS position error is smaller than that of PDAF. Also, the system parameters are correctly obtained even from incorrect initial values. Copyright © 2001 John Wiley & Sons, Ltd.     

Effects of solidification structure on fatigue crack initiation and fatigue strength in Al−Si−Mg cast alloys

Rotating-bending uniaxial fatigue tests and micro-fatigue crack initiation tests were carried out using a permanent mold cast (PMC) and semi-solid die cast (SDC) with Al−7%Si−0.35%Mg composition in order to examine the relationship between solidification structures and fatigue behaviors. The crack length was measured using a replication method. Fatigue strength was improved in SDC, which was almost consistent with the predicted fatigue strength using the size of Si particle cluster. Resistance to fatigue crack initiation and fatigue strength were improved in SDC owing to the finer Si cluster and to higher ultimate tensile strength. Fatigue crack in PMC was preferentially initiated at pores. For SDC, the fatigue crack was initiated at the Si particle/matrix interface, and then sucessively grew along eutectic cell boundaries.     

A 0.9 V 92 dB Double-Sampled Switched-RC Delta-Sigma Audio ADC

A 0.9 V third-order double-sampled delta-sigma audio ADC is presented. A new method using a combination of a switched-RC technique and a floating switched-capacitor double-sampling configuration enabled low-voltage operation without clock boosting or bootstrapping. A three-level quantizer with simple dynamic element matching was used to improve linearity. The prototype IC implemented in a 0.13 CMOS process achieves 92 dB DR, 91 dB SNR and 89 dB SNDR in a 24 kHz audio signal bandwidth, while consuming 1.5 mW from a 0.9 V supply. The prototype operates from 0.65 V to 1.5 V supply with minimal performance degradation.     

Facile modifications of polyimide via chloromethylation: II. Synthesis and characterization of thermocurable transparent polyimide having methylene acrylate side groups

From chloromethylated polyimide, a useful starting material for modification of aromatic polyimides, a thermocurable transparent polyimide having acrylate side groups was prepared. In the presence of 1,8‐diazabicyclo[5,4,0]undec‐7‐ene, chloromethylated polyimide was esterified with acrylic acid to synthesize poly(imide methylene acrylate). The polymer was soluble in organic solvent, which makes it possible to prepare a planar film by spin coating. The polymer film became insoluble after thermal treatment at 230 °C for 30 min. Optical transparency of the film at 400 nm (for 1 µm thickness) was higher than 98 % and not affected by further heating at 230 °C for 250 min. Adhesion properties measured by the ASTM D3359‐B method ranged from 4B to 5B. Preliminary results of planarization testing showed a high degree of planarization (DOP) value (>0.53). These properties demonstrate that poly(imide methylene acrylate) could be utilized as a thermocurable transparent material in fabricating display devices such as TFT‐LCD. Copyright © 2004 Society of Chemical Industry     

Properties of nanoporous organosilicate hybrid thin films with a bimodal pore size distribution

Low dielectric poly[methylsilsesquioxane‐ran‐trifluoropropylsilsesquioxane‐ran‐(2,4,6,8‐tetramethyl‐2,4,6,8‐tetraethylenecyclotetrasiloxane)silsesquioxane]s {P[M‐ran‐TFP‐ran‐(TCS)]SSQs} having various compositions were synthesized using trifluoropropyl trimethoxysilane, methyl trimethoxysilane and 2,4,6,8‐tetramethyl‐2,4,6,8‐tetra(trimethoxysilylethyl)cyclotetrasiloxane. The chemical composition of the polymers and the content of SiOH end‐groups were controlled by adjusting the reaction conditions, and they were characterized by ¹H‐NMR. The thermally decomposable trifluoropropyl groups on the P[M‐ran‐TFP‐ran‐(TCS)]SSQ backbone and heptakis(2,3,6‐tri‐O‐methyl)‐β‐cyclodextrin (CD) were employed as pore generators. The dielectric constants of the porous CD/P[M‐ran‐TFP‐ran‐(TCS)]SSQ films were in the range 2.0–2.7 (at 100 kHz) depending on the concentration of the porogens, and showed no change over 4 days under aqueous conditions. The pore size of the films showed a bimodal distribution, with diameters of ca 0.5–1.0 nm for those originating from the trifluoropropyl groups and 1.7 nm from the CD. The elastic modulus and hardness of the 30 vol% CD‐blended film with a dielectric constant of 2.26 were 2.40 and 0.38 GPa, respectively, as determined by a nanoindenter. Copyright © 2005 Society of Chemical Industry     

Slow eroding biodegradable multiblock poloxamer copolymers

Biodegradable multiblock poloxamers (BMPs) with gel duration of 8 h to several weeks were prepared by varying their molecular weights from 4000 to 40 000 g mol^?1. The molecular weight of the BMP was controlled by changing the poloxamer to coupling agent ratio. Assuming a micelle packing model of the BMP gel, as in the case of a poloxamer gel, the micelle properties and critical gel concentration of BMPs were investigated on the basis of the scaling concept. The findings suggest that the control of molecular weight by hydrolyzable groups can be a facile approach to optimize the gel properties for biomedical applications. Copyright © 2005 Society of Chemical Industry     

Steric requirements for coal swelling by amine bases

A set of six coals ranging in rank from lignite to hvA bituminous was swollen with a series of alkyl-substituted pyridines and a smaller set of 4-alkylanilines. The size and branching of the alkyl groups was varied and the effect of this variation on the dissolution of the amines in the coal and the resulting coal swelling was measured volumetrically. In a few cases, substituents which hindered the amine nitrogen were studied. The lignite and subbituminous coal have a much higher tolerance to branched, bulky groups than do the bituminous coals. The presence of tertiary groups in a solute strongly inhibits their dissolution in bituminous coals. Bituminous coals behave as if extensive parallel packing of structures occurs. Often, they can accept very large planar groups but have a low capacity for branched groups.     

Synthesis and characterization of an interpenetrating polymer network composed of poly(methacrylic acid) and poly(vinyl alcohol)

Temperature and pH‐responsive interpenetrating polymer network (IPN) hydrogels, constructed with poly(methacrylic acid) (PMAA) and poly(vinyl alcohol) (PVA), by a sequential IPN method, were studied. The characterization of IPN hydrogels was investigated by Fourier‐transform infrared spectroscopy, differential scanning calorimetry (DSC) and swelling under various conditions. The IPN hydrogels exhibited relatively high swelling ratios, in the range 230–380 %, at 25 °C. The swelling ratios of the PMAA/PVA IPN hydrogels were pH and temperature dependent. DSC was used for the quantitative determination of the amounts of freezing and non‐freezing water. The amount of free water increased with increasing PMAA content in the IPN hydrogels. Copyright © 2004 Society of Chemical Industry     

Application of a multi-channel system for continuous monitoring and an early warning system.

A multi-channel continuous toxicity monitoring system developed in our laboratory, based on two-stage mini-bioreactors, was successfully implemented in the form of computer-based data acquisition. The multi-channel system consists of a series of a two-stage minibioreactor systems connected by a fiber optic probe to a luminometer, and uses genetically engineered bioluminescent bacteria for the detection of the potential toxicity from the soluble chemicals. This system can be stably and continuously operated due to the separation of the culture reactor from the test reactor and accomplish easy and long-term monitoring without system shut down by abrupt inflows of severe polluting chemicals. Four different recombinant bioluminescent bacteria were used in different channels so that the modes of the samples toxicities can be reasonably identified and evaluated based upon the response signature of each channel. The bioluminescent signatures were delivered from four channels by switching one at once, while the data is automatically logged to an IBM compatible computer. We also achieved the enhancement of the system through the manipulation of the dilution rate and the use of thermo-lux fusion strains. Finally, this system is now being implemented to a drinking water reservoir and river for remote sensing as an early warning system.