T-Junction Loaded with Interdigital Capacitor for Differential Measurement of Permittivity

The microwave sensors have been successfully used for permittivity measurement. These sensors suffer from limited sensitivity and environmental effects. This article presents a novel T-junction highly sensitive microwave sensor for permittivity measurement of low-loss solid materials. The proposed sensor operation principle is based on downshifting the transmission zero (TZ) of the outputs of T-junction with the coupling of the material under test (MUT). The sensing section consists of an interdigital capacitor (IDC) located in between the lines of the T-junction. IDC is directly connected to output arms of T-junction, so that it could disturb the outputs strongly. Any change in electric field concentration in IDC directly is transmitted to the outputs and is translated as TZ change. Design steps including T-junction and IDC effects on outputs are presented in detail. The sensor operation principle is described through an equivalent circuit model, which is validated by simulation and experimental results. Two outputs of the proposed sensor show the same electrical performances, which allow differential operation mode. Hence, cross sensitivity due to environmental factors can be tolerated by the sensor. Measurement results of the fabricated prototype show 112-MHz frequency shift per unit permittivity change and a normalized sensitivity of 3.9%, which are larger than available similar sensors. The proposed sensor is implemented on a 22.22 × 18.76 × 1.6 mm3 printed circuit board.</p

Dual Frequency Microwave Resonator for Non-invasive detection of Aqueous Glucose

A novel dual-band microwave sensor for noninvasive detection of glucose concentration is presented. The proposed sensor consists of an open-loop resonator coupled to the input and the output of the structure. The resonator is loaded with modified split-ring resonators (SRRs) for dual-band operation as a sensing area. The open-loop resonator with electric coupling operating at low band functions as a host. The SRRs embedded into the open-loop resonator operate at a high band. In the proposed sensor, the overall size is miniaturized using the embedded resonator structure. This configuration has two transmission poles (TPs) and one transmission zero (TZ) in transmission coefficients, which are all sensitive to glucose-level (GL) variation. A dielectric container made with 3-D printer is used for dropping the aqueous glucose samples on the sensing section of the sensor. The experimental results obtained from the prototype having a dielectric container shows two resonance frequencies at 1.8 and 2.67 GHz as well as a TZ at 2.32 GHz. A glucose solution with deionized water in the range from 89 to 456 mg/dL is used in the measurements. For this range of glucose concentrations, the experimental frequency resolutions are 0.78 and 0.95 MHz/(mg/dL) based on the TP and the TZ, respectively.</p

Loss reduction in substrate integrated waveguide structures

A method for decreasing the loss in substrate integrated waveguide (SIW) structures is introduced. In this method, the dielectric substrate is partially removed. Accordingly, dielectric loss reduction has been explicated analytically. Its equivalence to the rectangular waveguide of solid walls which is partially filled with dielectric has been identified. A novel topology for demonstrating the idea is established and a low loss three port substrate integrated waveguide power divider is presented. This SIW power divider shows lower loss than conventional SIW power dividers. Proper TRL standards are realized for removing the effect of transition and/or matching sections in measurement process. For a low-loss three-port PSIW power divider, the return loss below 10 dB and transmission coefficients between -3 dB to -3.5 dB from 8.75 GHz to 10 GHz have been achieved. The measured amplitude imbalance is less than ±0.2 dB, and the measured phase difference between <S21 and <S31 is about 40 in the same frequency band

Broad Band Equal-Length And Equal-Width Substrate Integrated Waveguide Four Channel Power Divider

In this letter a novel broad band substrate integrated waveguide (SIW) power divider is proposed. It consist of four output channels made by SIW with equal length and equal width. Design equations and process are given with mathematical analysis. The propagation constant of the output signals have been adjusted by utilize only four via in the middle of the output arms. As a result a novel equal output power divider, is obtained accordingly. The experimental results of a prototype at 10 GHz shows 3.1 GHz bandwidth in both simulation and measurement results. Return loss and transmission coefficients have good agreement with simulation results in considered band

An Adjustable Fuzzy Chance-Constrained Network DEA Approach with Application to Ranking Investment Firms

This paper presents a novel approach for performance appraisal and ranking of decision-making units (DMUs) with two-stage network structure in the presence of imprecise and vague data. In order to achieve this goal, two-stage data envelopment analysis (DEA) model, adjustable possibilistic programming (APP), and chance-constrained programming (CCP) are applied to propose the new fuzzy network data envelopment analysis (FNDEA) approach. The main advantages of the proposed FNDEA approach can be summarized as follows: linearity of the proposed FNDEA models, unique efficiency decomposing under ambiguity, capability to extending for other network structures. Moreover, FNDEA approach can be applied for ranking of two-stage DMUs under fuzzy environment in three stages: 1) solving the proposed FNDEA model for all optimistic-pessimistic viewpoints and confidence levels, 2) then plotting the results and drawing the surface of all efficiency scores, 3) and finally calculate the volume of the three-dimensional shape in below the efficiency surface. This volume can be as ranking criterion. Remarkably, the presented fuzzy network DEA approach is implemented for performance appraisal and ranking of investment firms (IFs) with two-stage processes including operational and portfolio management process. Illustrative results of the real-life case study show that the proposed approach is effective and practically very useful

Comparison of Methoxyisobutylisonitrile Scintigraphy and Ultrasonography in Preoperative Localization of Secondary Hyperparathyroidism

Background: In patients with secondary hyperparathyroidism, the four glands are not uniformly enlarged; therefore, preoperative localization is difficult in comparison with primary hyperparathyroidism. The aim of&nbsp;this study was to compare the usefulness of 99mTc-sestamibi scintigraphy versus ultrasonography in the preoperative assessment of patients with secondary hyperparathyroidism.Methods: Between October 2008 and March 2012, 25 uremic patients with secondary hyperparathyroidism underwent 99mTc-sestamibi scintigraphy and high resolution ultrasonography before total or subtotal parathyroidectomy. We measured plasma concentration of intact parathyroid hormone (PTH), calcium, phosphorus, and alkaline phosphatase (ALP) before parathyroidectomy.Results: Sensitivity and positive predictive value (PPV), respectively, were 47.3% and 97.8% for MIBI scintigraphy, and 69.5% and 96.9% for ultrasonography. The sensitivity of combined techniques was 84.2%.&nbsp;There was a positive correlation between the parathyroid glands’ weight and serum calcium level, and positive MIBI scintigraphy and ultrasonography results. However, there was no correlation between the preoperative serum PTH, phosphorus, alkaline phosphatase (ALP), dialysis duration, and parathyroid glands’ weight.Conclusions: Ultrasonography is a reliable non-invasive localization tool. It has greater sensitivity in localizing parathyroid glands in secondary hyperparathyroidism than scintigraphy

Evaluating Occupational Exposure of Workers for Metallurgy with Alkanol Amines

Liquids being used in metallurgy are a composition of dangerous chemicals including Alkanol amines. Alkanol amines include Mono-, Di- and 3- ethanol amine. Alkanol amines are used as lubricant in metallurgy. Dermal absorption of these chemical substances is so important and some studies are being done about carcinogenesis of these chemical substances. Meanwhile, ethanol amine has been recognized as a factor causing occupational asthma. The present study was done on 29 turnery and rolling workers in Cupper Industrial Complex of Sarcheshmeh in descriptive- sectional manner. Data related to concentration of Alkanol amines in the atmosphere were gathered with the method proposed by NIOSH and data for pulmonary function were extracted from spirometry experiments. Demographic data were obtained from medical files of the workers. Statistical tests were carried out using software SPSS. In this study, workers' Time Weighted Average (TWA) individual exposure to Mono-ethanol amine (MEA) with density scope 0.03- 1.16, exposure to Di-ethanol amine (DEA) with density scope 0.36-1.35 and exposure to TEA with density scope 0.49-1.28 equal 0.54, 0.87 and 0.85 mg/m3 respectively without occupational group separation for each. Also, FVC reduction in studied individuals without occupational group separation was 3.17% (SD= 6.55%). The results indicated that workers' Time Weighted Average exposure to Mono-Di-Tri- ethanol amine was lower than occupational legal limit. In rolling process, exposure to Alkanol amines is lower compared to other processes of metallurgy because of semi- enclosure of this process. Having done Pearson correlation test to determine relation between individuals' work experience and FVC reduction, it was observed that there is no meaningful relation between these two variables