Joint Channel Coding Based on Principal Component Analysis

This paper proposes a new joint channel coding algorithm based on principal component analysis. A conventional joint channel coder using passive downmixing undergoes a reduction of both the primary‐to‐ambient energy ratio (PAR) of the downmix signal and the panning gain ratio of the primary source. The proposed system preserves the PAR of the downmix signal by using active downmixing which reflects spatial characteristic. The proposed system also improves the accuracy of the panning gain ratio estimation. Computer simulations and subjective listening tests verify the performance of the proposed system.     

Smart CMOS Image Sensor With High SBR and Subpixel Resolution for Light-Section-Based Range Finding

Light-section (LS)-based range finders are commonly used for obstacle recognition in home service robots and autonomous vehicles. This paper proposes a smart CMOS image sensor for LS-based range finding. The proposed sensor can detect the laser light, even under very strong ambient-illumination levels by using a multiple-capture frame-correlated double sampling (F-CDS), which is realized with an inverter-based switched-capacitor F-CDS accumulator. The proposed sensor also includes on-chip winner-take-all circuits that significantly reduce the software and hardware complexity of interpolation for the subpixel resolution. The prototype chip was fabricated using a 0.35-mum CMOS process. The measurement results show that the proposed sensor can detect a laser line with an intensity that is 56.5 dB lower than that of the ambient illumination, providing a spatial resolution of plusmn0.16 pixels.     

Dual-band transmitters using digitally predistorted frequency multipliers for reconfigurable radios

Two methods for reconfigurable transmitters using frequency multipliers in conjunction with digital predistortion linearizers are developed. One method utilizes a circuit topology that can be switched between a fundamental-mode in-phase combined amplifier, and a push-push frequency doubler using input phasing. Investigation to maximize output harmonics out of regular power amplifiers (PAs) was performed, and the implementation of the device was successful for the amplifier- and doubler-mode operation. To satisfy optimal load-line conditions for the operation in both modes, a bi-tuned output-combining technique is introduced as well. Measurement results indicate that the circuit is able to transmit 28 dBm of output power at 900 MHz in the amplifier mode, and 22 dBm at 1800 MHz in the doubler mode. In combination with predistortion linearization, the reconfigurable transmitter was shown to be capable of amplifying IS-95B code-division multiple-access (CDMA) signals with an adjacent-channel power ratio (ACPR) up to -58dBc/30kHz. The second suggested method utilizes a fundamental-frequency PA followed by a varactor multiplier that can be bypassed with an RF switch. A varactor-diode doubler with a saturated conversion loss of 1.3 dB was built and tested. Using predistortion linearization techniques on both the PA and doubler, an ACPR of -53dBc/30kHz at 885-kHz offset was achieved for a CDMA signal transmitted at 1850 MHz.     

Sensitivity Controllable CMOS Image Sensor Pixel Using Control Gate Overlaid on Photodiode

A new sensitivity controllable pixel structure is proposed for CMOS active-pixel image sensor. The proposed pixel structure has a sensitivity control gate overlaid on the photodiode. The sensitivity of the pixel is controlled by the bias voltage of the control gate that forms a variable accumulation-mode MOS capacitor. The prototype sensor is fabricated with a 0.35-mum CMOS process and consists of 60 times 240 pixels with 5.6-mum pixel pitch. Measurement results show that the sensitivity of the photodiode can be controlled by a factor of 4.     

Active control of low-frequency noise in bubbly water-filled pipes

This paper describes an active silencer system for low-frequency noise in water-filled pipes, with implementation in marine vessels and structures in mind. Active noise control in underwater environment has its unique challenges arising from bubbles. In this light the effect of bubbles on active noise control in water-filled pipes is explored, and a design guideline for a robust active silencer is proposed. The silencer consists of an underwater sound source, an error hydrophone, and an electronic controller programmed with an adaptive filter. The adaptive filter is updated using the filtered-x least mean square algorithm. Estimation of the incoming noise is performed using an adaptive notch filter. The performance of the active silencer is tested for pure tone noises below 500 Hz in a water-filled pipe connected to a reservoir. Notable reduction of noise is achieved with varying degrees of success at different bubble fractions.

     

Lubrication characteristics of nano-oil with different degrees of surface hardness of sliding members

In this study, the lubrication characteristics of sliding members were compared with the changes in the hardness of friction surfaces and the application of nano-oil. The materials of the specimens were gray cast iron (AISI 35 and AISI 60) and nickel chromium molybdenum steel (AISI 4320). The friction coefficients and the temperature variations of the frictional surfaces were measured with a disk-on-disk tribotester under a fixed rotation speed. The friction surfaces were observed with a scanning electron microscope (SEM). The friction coefficients of the plate surface increased as the hardness difference increased. The friction coefficient after the lubrication with nano-oil was less than that after lubrication with mineral oil. This is because a spherical nanoparticle plays the role of a tiny ball bearing between the frictional surfaces that improve the lubrication characteristics.     

Low Voltage, Low Power, Inverter-Based Switched-Capacitor Delta-Sigma Modulator

An operational transconductance amplifier (OTA) is a major building block and consumes most of the power in switched-capacitor (SC) circuits, but it is difficult to design low-voltage OTAs in scaled CMOS technologies. Instead of using an OTA, this paper proposes an inverter-based SC circuit and its application to low-voltage, low-power delta-sigma (DeltaSigma) modulators. Detailed analysis and design optimizations are also provided. Three inverter-based DeltaSigma modulators are implemented for an implantable pacemaker, a CMOS image sensor, and an audio codec. The modulator-I for an implantable pacemaker achieves 65-dB peak-SNDR for 120-Hz bandwidth consuming 0.73 muW with 1.5 V supply. The modulator-II for a CMOS image sensor implemented with 320-channel parallel ADC architecture achieves 63-dB peak-SNDR for 8-kHz bandwidth consuming 5.6 muW for each channel with 1.2-V supply. The modulator-III for an audio codec achieves 81-dB peak-SNDR with 20-kHz bandwidth consuming 36 muW with 0.7-V supply. The prototype DeltaSigma modulators achieved high power efficiency maintaining sufficient performances for practical applications.     

A Dual-Capture Wide Dynamic Range CMOS Image Sensor Using Floating-Diffusion Capacitor

A dual-capture wide dynamic range CMOS image sensor using an in-pixel floating-diffusion (FD) storage capacitor is proposed. The proposed structure uses the FD as a storage capacitor. The potential of the FD node is read out using a floating-gate capacitor without a contact metallization of the FD node to reduce the leakage. The proposed sensor was fabricated using a 0.35-mum CMOS process. The chip includes 320 times 240 pixels whose pitch is 5.6 mum and whose fill factor is 36%. The measurement results show 100-dB dynamic range, and the leakage at the non-metalized FD is reduced to about one-third of that of the conventional FD with the contact metallization.     

Remediation of contaminated soil with diesel by soil venting technique

Soil venting is an effective and widely used method to remediate soils contaminated with hydrocarbons. A set of experiments was conducted in a one-dimensional soil column test section to investigate the effect of preheating the air in a soil venting system. Diesel fuel, which was used as the only contaminant, was analyzed and modeled with 14 major components. Temperature readings from the thermocouples, located in the test section were recorded during the experiment and the composition of hydrocarbons in the effluent air was also monitored. The results show that the diesel components are removed according to their volatility with the higher volatility components being removed first. An increase in venting air flow rate or inlet air temperature can considerably speed up the process. The increase in inlet air temperature is very effective in increasing the removal rate of the heavier components. A one-dimensional, non-isothermal, complete mixing model was used to predict the evaporation rates of the contaminant components and temperature distribution in the test section. Model results have been found to be in good agreement with the experimental data.