Sliding-Mode Amplitude Control Techniques for Harmonic Oscillators

This paper investigates both theoretical and implementation-level aspects of switching-feedback control strategies for the development of harmonic oscillators. We use sliding-mode compensation based on various norms of the system state to achieve amplitude control over a wide-tuning range. A 7.6-MHz I/Q LC oscillator is developed and tested. Measurements show that implementation of the proposed switch-based amplitude controller provides accurate amplitude control over the entire frequency tuning range while inducing only a minor phase noise degradation (of less than 2 dBc/Hz).     

Effect of pre-soaking treatments on the nutritional profile and browning index of sweet potato and yam flours

The use of sweet potato and yams for product development is hindered by the discoloration from enzymatic and non-enzymatic browning. The effect of pre-soaking treatments on the nutritional changes and browning index (BI) of sweet potato and yam (greater yam and white yam) flours was investigated. Ascorbic acid (AsA), citric acid (CA), acetic acid (AA) and sodium metabisulfite (SMS) were used for soaking at three concentrations (0.25%, 0.50% and 1.00%) and two durations (1 h and 2 h). AsA and SMS removed more starch during soaking of sweet potato, while CA and AA removed more starch from greater yam and CA removed more starch from white yam. Highest removal of reducing sugars was observed in sweet potato in AA, while CA removed maximum reducing sugars from both the yams. Phenol and total free amino acid (TFA) levels were more in SMS treatment than the control sweet potato flour, and least in AA (2 h). Whilst AsA raised the phenols and TFA in greater yam, it removed phenols to the maximum in white yam. Maximum BI was in AsA treatment for the three crops, and least for flour from CA (0.25%) treated yams and AA (1.00%) treated sweet potato.Industrial RelevanceBrowning resulting from enzymatic and non-enzymatic reactions is a major drawback in the processing of sweet potato and yams for product development. The study showed that this could be successfully tackled through soaking the slices in low cost chemicals like acetic acid or citric acid and sodium metabisulfite at low concentrations. The treated slices yielded flour with very low browning indices compared to the respective native flours, which could enhance the potential of such flours in the development of food products.     

Evaluating combustion,performance and emission characteristics of diesel engine using karanja oil methyl ester biodiesel blends enriched with HHO gas

With a specific end goal to take care of the worldwide demand for energy, a broad research is done to create alternative and cost effective fuel. The fundamental goal of this examination is to investigate the combustion, performance and emission characteristics of diesel engine using biodiesel blends enriched with HHO gas. The biodiesel blends are gotten by blending KOME obtained from transesterification of karanja oil in various proportions with neat diesel. The HHO gas is produced by the electrolysis of water in the presence of sodium bicarbonate electrolyte. The constant flow of HHO gas accompanied with biodiesel guarantees lessened brake specific fuel consumption by 2.41% at no load and 17.53% at full load with increased the brake thermal efficiency by 2.61% at no load and 21.67% at full load contrasted with neat diesel operation. Noteworthy decline in unburned hydrocarbon, carbon monoxide, carbon-dioxide emissions and particulate matter with the exception of NO_x discharge is encountered. The addition of EGR controls this hike in NO_x with a slight decline in the performance characteristics. It is clear that the addition of HHO gas with biodiesel blends along with EGR in the test engine improved the overall characterization of engine.     

Stable solution processed hole injection material for organic light-emitting diodes

A new aqueous based polymer, Plexcore® OC AQ1200 (AQ1200) was used as a hole injection layer (HIL) in organic light emitting diodes (OLEDs) and the device results are compared with polyethylene dioxythiophene:polystyrene sulfonate (PEDOT:PSS) in terms of injection efficiency and stability. Dark injection transient measurements show a higher injection efficiency in hole-only devices using AQ1200 HIL compared with PEDOT:PSS. Using AQ1200 as an HIL, high efficiency phosphorescent OLEDs are demonstrated to have a long lifetime, with an estimated operational half lifetime (LT 50) of more than 8000 h from an initial luminance of 1000 cd/m².     

Distributed balanced photodetectors for high-performance RFphotonic links

A novel velocity-matched distributed balanced photodetector with a 50-Ω coplanar waveguide output transmission line has been experimentally demonstrated in the InP-InGaAs material system. Distributed absorption and velocity matching are employed to achieve high-saturation photocurrent. A common mode rejection ratio of 27 dB has been achieved. The RF link experiment conducted at 6.48 GHz shows that the laser intensity noise has been suppressed by more than 17 dB     

Comparative evaluation of performance,emission, lubricant and deposit characteristics of spark ignition engine fueled with CNG and 18% hydrogen-CNG

Gaseous fuels such as CNG and hydrogen are promising alternative fuels which receive more attention all over the world. This paper investigates the effect of compressed natural gas (CNG) and 18% hydrogen blended compressed natural gas (HCNG) on a retrofitted gasoline genset engine’s performance, emissions, deposits and lubricants under long duration testing. During the 60 h test, lower BSFC, CO and HC are observed for HCNG with the penalty of NOx values. The deposits of iron on spark plug and cylinder liner are higher for HCNG compared to CNG. As kinematic viscosity and TBN values of lubricant decreased significantly with HCNG, it has resulted in higher concentration of wear metals (iron and copper) in the used oil.     

Robust sound localization in 0.18 /spl mu/m CMOS

This paper presents a hardware implementation of a sound localization algorithm that localizes a single sound source by using the information gathered by two separated microphones. This is achieved through estimating the time delay of arrival (TDOA) of sound at the two microphones. We have used a TDOA algorithm known as the "phase transform" to minimize the effects of reverberations and noise from the environment. Simplifications to the chosen TDOA algorithm were made in order to replace complex operations, such as the cosine function, with less expensive ones, such as iterative additions. The custom digital signal processor implementing this algorithm was designed in a 0.18-/spl mu/m CMOS process and tested successfully. The test chip is capable of localizing the direction of a sound source within 2.2/spl deg/ of accuracy, utilizing approximately 30 mW of power and 6.25 mm/sup 2/ of silicon area.     

Hardware implementation perspectives of digital video watermarking algorithms

We consider hardware implementation aspects of the digital watermarking problem through the implementation of a well-known video watermarking algorithm called just another watermarking system (JAWS); we discuss the time and area constraints that must be satisfied by a successful hardware implementation. A hardware architecture that implements the algorithm under the constraints is then proposed. The architecture is analyzed to gain an understanding of the relationships between algorithmic features and implementation cost. Some general findings of this work that can be applied toward making algorithmic developments more amenable to hardware implementation are finally presented.