A fully integrated low-IF CMOS GPS radio with on-chip analog image rejection

A fully integrated Global Positioning System (GPS) radio is presented. Low-IF architecture was used for a high level of integration and low power consumption. An on-chip analog image-reject filter provides 18 dB of image-noise rejection to prevent noise figure (NF) degradation. With image rejection performed in the analog radio, a single-path (nonquadrature) output was used. The integrated synthesizer only requires an off-chip phase-locked loop-filter to function. Implemented in a 0.35-/spl mu/m 2P4M CMOS process, the integrated radio has a chip area of 9.5 mm/sup 2/. The radio operates over a wide range of voltage and temperature, from 2.2 to 3.6 V and from -40/spl deg/C to +85/spl deg/C and consumes 27 mW from a 2.2-V supply. The receiver has 4 dB NF.     

Application of a dispersive micro‐solid‐phase extraction method for pre‐concentration and ultra‐trace determination of cadmium ions in water and biological samples

A method for the trace determination of cadmium ions in water, human urine and human blood serum samples using ultrasonic‐assisted dispersive micro‐solid‐phase extraction (UA‐D‐μSPE) was developed. Silica‐coated magnetic nanoparticles were coated with polythiophene, and the resulting sorbent was characterized using thermogravimetry, differential thermal analysis, scanning electron microscopy, Fourier transform infrared spectrometry and X‐ray diffraction. Following UA‐D‐μSPE, cadmium ions were quantified using graphite furnace atomic absorption spectrometry. A Box–Behnken design was used for optimization of important sorption and desorption parameters in UA‐D‐μSPE: in the sorption step, pH of solution, sorption amount and sonication time for sorption; in the desorption step, concentration of eluent, volume of eluent and sonication time. The optimum conditions for the method were: pH of solution, 7.5; sonication time for sorption, 3 min; sorption amount, 35 mg; type and concentration of eluent, HCl and 1.1 mol l^?1; volume of eluent, 360 μl; sonication time for desorption, 110 s. Under the optimized conditions the limit of detection and relative standard deviation for the detection of cadmium ions by UA‐D‐μSPE were found to be 0.8 ng l^?1 and <6%, respectively.     

Trimethylsilylation of Alcohols and Phenols,and Direct Acetylation of Silyl Ethers Catalyzed by Fe(ClO4)3.6H2O

In this article, a mild and efficient protocol for the trimethylsilylation of various aliphatic and benzylic alcohols and phenols with trimethylsilyl chloride using a catalytic amount of ferric perchlorate at room temperature and relatively short reaction times in good to excellent yields is reported. Direct acetylation of trimethylsilyl ethers catalyzed with Fe(ClO ₄ ) ₃ .6H ₂ O(0.02 mmol)/Fe(ClO ₄ ) ₃ SiO ₂ (0.2 g) using acetic anhydride at ambient temperature is also reported.     

Energy spectrum of multi-radiation of X-rays in a low energy Mather-type plasma focus device

The multi-radiation of X-rays was investigated with special attention to their energy spectrum in a Mather-type plasma focus device （operated with argon gas）. The analysis is based on the effect of anomalous resistances. To study the energy spectrum, a four-channel diode X-ray spectrometer was used along with a special set of filters. The filters were suitable for detection of medium range X-rays as well as hard X-rays with energy exceeding 30 keV. The results indicate that the anomalous resistivity effect during the post pinch phase may cause multi-radiation of X-rays with a total duration of 300 ± 50 ns. The significant contribution of Cu-Kα was due to the medium range X-rays, nonetheless, hard X-rays with energies greater than 15 keV also participate in the process. The total emitted X-ray energy in the forms of Cu-K and Cu-K/3 was around 0.14 ± 0.02 （J/Sr） and 0.04 ±0.01 （J/Sr）, respectively. The total energy of the emitted hard X-ray （〉 15 keV） was around 0.12± 0.02 （J/Sr）.     

Mechatronic Design Quotient as the Basis of a New Multicriteria Mechatronic Design Methodology

A concurrent, integrated, and multicriteria methodology is presented for the conceptual design of mechatronic systems. It uses an evaluation model called mechatronic design quotient (MDQ) to facilitate decision-making in the design process. A nonlinear fuzzy integral is used for the aggregation of criteria in MDQ, thereby accommodating possible correlations among them. The performance of the developed methodology is validated by applying it to an industrial fish cutting machine called Iron Butcher-an electromechanical system that falls into the class of mixed or multidomain systems     

An efficient correlation for calculating compressibility factor of natural gases

Compressibility factor (z-factor) values of natural gases are necessary in most petroleum engineering calculations. Necessity arises when there are few available experimental data for the required composition, pressure and temperature conditions. One of the most common methods of calculating z-factor values is empirical correlation. Firstly, a new correlation based on the famous Standing-Katz (S-K) Chart is presented to predict z-factor values. The advantage of this correlation is that it is explicit inzand thus does not require an iterative solution as is required by other methods. Secondly, the comparison between new one and other correlations is carried out and the results indicate the superiority of the new correlation over the other correlations used to calculate z-factor.     

Strongly regular graphs with non-trivial automorphisms

The possible existence of 16 parameter sets for strongly regular graphs with 100 or less vertices is still unknown. In this paper, we outline a method to search for strongly regular graphs by assuming a non-trivial automorphism of prime order. Among these unknown parameter sets, we eliminated many possible automorphisms, but some small prime orders still remain. We also found 6 new strongly regular graphs with parameters (49,18,7,6).     

Synthesis and application of a thermosensitive tri-block copolymer as an efficient sample treatment technique for preconcentration and ultra-trace detection of lead ions

We have designed and synthesized a thermosensitive tri-block copolymer for selective trace extraction of Pb(II) ions from biological and food samples. The polymer was characterized by Fourier transform IR and NMR spectroscopy, and by gel permeation chromatography. The critical aggregation concentration and lower critical solution temperature were determined via fluorescence and UV spectrophotometry, respectively. The effects of solution pH value, amount of copolymer, of the temperature on extraction and on phase separation, and of the matrix on the extraction of Pb(II) were optimized. Pb(II) ions were then quantified by FAAS. The use of this copolymer resulted in excellent figures of merit including a calibration plot extending from 0.5 to 160 μg L^?1 (with an R² of >0.99), a limit of detection (LOD) as low as 90 pg L^?1, an extraction efficiency of >98 %, and relative standard deviations of <4 % for eight separate extraction experiments.

Amplify-and-Forward Relay Networks Under Received Power Constraint

Relay networks have received considerable attention recently, especially when limited size and power resources impose constraints on the number of antennas at each node. While fixed and mobile relays can co-operate to improve reception at the desired destination, they also contribute to un-intended interference for neighboring cells reusing the same frequency. In this paper, we propose and analyze a relay scheme to simultaneously maximize SNR and minimize MSE, for an amplify-and-forward (AF) relay network operating under a receive power constraint guaranteeing that the received signal power is bounded to control interference to neighboring cells. If the intended destination lies at the periphery of the cell, then the proposed scheme guarantees that the total power leaking into neighboring cells is bounded. The optimal relay factors are provided for both correlated and uncorrelated noise at the relays. Simulation results are presented to verify the analysis.