Equivalent circuit for capacitive micromachined ultrasonic transducers to predict anti-resonances

Equivalent circuit models have been long used to evaluate the dynamics of the capacitive micromachined ultrasonic transducer (CMUT). An important parameter in the characterization of a CMUT is the anti-resonance frequency, which limits the immersion bandwidth. However, there is no equivalent circuit model that can accurately determine the anti-resonance frequency of a membrane. In this work, we present an improved lumped element parametric model for immersed CMUT. We demonstrate that the proposed equivalent circuit model accurately predicts anti-resonance and higher order mode frequencies, in addition to that of the fundamental mode. The proposed circuit model is in good agreement with device characteristics calculated using the finite element method and experimentally measured data.

     

Considering the possibility of bonding utilizing cold sintering for ceramic adhesives

Here, we introduce a new bonding technique that enables the joining of different materials at low temperatures and provides a bond superior to that of polymer adhesives at high temperatures, in temperature ranges between 250°C and 500°C. This technique involves a low temperature sintering process that is termed the “Cold Sintering Process,” where a dielectric composite powder material is sintered to function as the adhesive between two other materials being bonded. In order to characterize and further discuss the potential of this new bonding methodology, which we call Cold Sintering Ceramic Bonding (CSCB), we demonstrate the initial mechanical characteristics of samples with sandwich structures of mesh/CSCB/mesh, including four‐point bending, micro‐indentation, and adhesion pull tests. Where appropriate, we compare mechanical properties against low and high temperature epoxies and demonstrate that the CSCB matches up competitively with the epoxies at low temperatures and remains strong at temperatures well above those where standard polymer adhesives fail. Transmission electron microscopy show a high quality interface between a stainless steel plate and the ceramic after the CSCB.     

基于凝结水变负荷技术的深度滑压节能控制

针对发电机组的一次调频和自动发电控制(AGC)的负荷控制品质与稳定低节流损失运行的机组节能需求产生矛盾的问题,以及现有凝结水变负荷技术和滑压优化技术的局限性,提出了基于凝结水变负荷技术的深度滑压节能控制策略,通过凝结水变负荷提高机组响应电网一次调频和AGC指令的能力,从而实现机组的最优滑压运行。以某亚临界350 MW机组为例,对基于凝结水变负荷技术的深度滑压节能控制策略进行了可行性和有效性验证。结果表明,机组在达到电网考核指标的前提下实现了深度滑压节能自动控制,节流损失大幅降低,每台机组年平均可节约煤耗1.13g/(kW·h),按煤价600元/t计算,每年可节约62.2万元,节能效果显著。同时,缓解了长期存在的电网一次调频和AGC考核与机组节能运行的矛盾。     

Comparative Analysis of Coding and Non-Coding Features within Insect Tolerance Loci in Wheat with Their Homologs in Cereal Genomes

Food insecurity and malnutrition have reached critical levels with increased human population, climate fluctuations, water shortage; therefore, higher-yielding crops are in the spotlight of numerous studies. Abiotic factors affect the yield of staple food crops; among all, wheat stem sawfly (Cephus cinctus Norton) and orange wheat blossom midge (Sitodiplosis mosellana) are two of the most economically and agronomically harmful insect pests which cause yield loss in cereals, especially in wheat in North America. There is no effective strategy for suppressing this pest damage yet, and only the plants with intrinsic tolerance mechanisms such as solid stem phenotypes for WSS and antixenosis and/or antibiosis mechanisms for OWBM can limit damage. A major QTL and a causal gene for WSS resistance were previously identified in wheat, and 3 major QTLs and a causal gene for OWBM resistance. Here, we present a comparative analysis of coding and non-coding features of these loci of wheat across important cereal crops, barley, rye, oat, and rice. This research paves the way for our cloning and editing of additional WSS and OWBM tolerance gene(s), proteins, and metabolites.     

Fuzzy logic approach in resource classification

Conventional geostatistical prediction methods can be used to carry out resource classification in ore beds and for reliability measurements. A field investigation based on lignite thickness data was conducted for resource classification in Eskisehir-Mihaliccik-Koyunagili coal basin. Moreover, a fuzzy logic-based resource classification method has been recently proposed to eliminate the uncertainties encountered in the conduct of conventional resource classification procedure. Fuzzy logic-based classification provides gradual transitions between two adjacent resource classes. In addition, the proposed method can classify each block by assigning a membership degree for handling decision-making problems encountered in conventional resource classification methods.     

Enzymatic degradation behavior and cytocompatibility of silk fibroin–starch–chitosan conjugate membranes

The objective of this study was to investigate the influence of silk fibroin and oxidized starch conjugation on the enzymatic degradation behavior and the cytocompatability of chitosan based biomaterials. The tensile stress of conjugate membranes, which was at 50 Megapascal (MPa) for the lowest fibroin and starch composition (10 weight percent (wt.%)), was decreased significantly with the increased content of fibroin and starch. The weight loss of conjugates in α-amylase was more notable when the starch concentration was the highest at 30 wt.%. The conjugates were resistant to the degradation by protease and lysozyme except for the conjugates with the lowest starch concentration. After 10 days of cell culture, the proliferation of osteoblast-like cells (SaOS-2) was stimulated significantly by higher fibroin compositions and the DNA synthesis on the conjugate with the highest fibroin (30 wt.%) was about two times more compared to the native chitosan. The light microscopy and the image analysis results showed that the cell area and the lengths were decreased significantly with higher fibroin/chitosan ratio. The study proved that the conjugation of fibroin and starch with the chitosan based biomaterials by the use of non-toxic reductive alkylation crosslinking significantly improved the cytocompatibility and modulated the biodegradation, respectively.     

Prediction of Damage Factor in end Milling of Glass Fibre Reinforced Plastic Composites Using Artificial Neural Network

Glass fibre reinforced plastic (GFRP) composites are an economic alternative to engineering materials because of their superior properties. Some damages on the surface occur due to their complex cutting mechanics in cutting process. Minimisation of the damages is fairly important in terms of product quality. In this study, a GFRP composite material was milled to experimentally minimise the damages on the machined surfaces, using two, three and four flute end mills at different combinations of cutting parameters. Experimental results showed that the damage factor increased with increasing cutting speed and feed rate, on the other hand, it was found that the damage factor decreased with increasing depth of cut and number of the flutes. In addition, analysis of variance (ANOVA) results clearly revealed that the feed rate was the most influential parameter affecting the damage factor in end milling of GFRP composites. Also, in present study, Artificial Neural Network (ANN) models with five learning algorithms were used in predicting the damage factor to reduce number of expensive and time-consuming experiments. The highest performance was obtained by 4-10-1 network structure with LM learning algorithm. ANN was notably successful in predicting the damage factor due to higher R² and lower RMSE and MEP.     

A new approach for rebalancing of U-lines with stochastic task times using ant colony optimisation algorithm

In real world, line balancing involves existing lines in existing factories and the line typically needs to be rebalanced rather than balanced. Rebalancing of a U-line can be defined as a changeover process from its initial configuration to a new configuration for a while due to the reasons such as demand variations, changes in product design and changes in task times, etc. This study defines U-line rebalancing problem with stochastic task times and proposes a solution procedure based on ant colony optimisation. The objective of the proposed algorithm is to minimise total cost of rebalancing which is the sum of task transposition costs, workstation opening/closing costs and operating costs of workstations for a particular planning horizon. A comprehensive experiment is conducted to generate problem instances and to compare rebalancing costs of U-lines by means of several factors. A total of 6600 rebalancing solutions are obtained and several comparisons are performed.     

Extraction of Bioactive Compounds from Milled Grape Canes (Vitis vinifera) Using a Pressurized Low-Polarity Water Extractor

Trans-resveratrol and trans-ε-viniferin were extracted from milled grape canes using pressurized low-polarity water. The effects of temperature were significant for both compounds (p ≤ 0.05): extraction at 160 °C resulted in a 40% loss of trans-resveratrol compared to 95 °C while reduction of trans-ε-viniferin at both temperatures remained at 30%. Increasing ethanol concentration from 0% to 25% increased the extraction of total phenolics and trans-ε-viniferin by 44% and 489%, respectively. Solvent flow rate also influenced trans-ε-viniferin extraction. Antioxidant activity showed a strong correlation with total phenolic content of the extracts, and the two target phenolic compounds. Except for the modifier concentration, the extraction parameters studied were not statistically significant with respect to the antioxidant activity of extracts (p > 0.05). Effective diffusivities of trans-resveratrol multiplied from 3.3 × 10⁻¹¹ to 10.4 × 10⁻¹¹ m²/s by three times with increasing temperature. The modified Gompertz equation satisfactorily explained the extraction of the stilbenes investigated.     

Derivation of low-power first-order low-pass,high-pass and all-pass filters

In this letter, a new voltage-mode (VM) configuration for providing low-power and simultaneous realization of first-order low-pass, high-pass and all-pass filters is presented. The output of the all-pass filter is taken differentially. The proposed circuit contains low number of components, i.e., only two NMOS transistors, a floating battery, a grounded capacitor and a floating resistor. Adding two NMOS transistors to the proposed circuit it is modified as an all-pass filter with a single-ended output. The main advantage of the presented circuits in comparison with other counterparts is their extremely low power dissipation. Moreover, the floating resistor can be replaced with an additional NMOS transistor in triode region to provide electronic tunability. Simulation results using SPICE program are given to demonstrate the performance of the proposed circuit.