Stability problems in universal current-mode filters

Analog circuit designers have usually focused on the design of circuits employing a minimum number of components, occupying less area and dissipating less power. However, some important issues such as signal limitations and especially stability problems of the analog circuits have not received considerable attention in the literature. Hence, the work described in this paper deals with the stability problems of two new current-mode analog filters employing multiple output current controlled conveyors (MOCCCIIs). Toward that end, a single pole model is replaced for each non-ideal current gain of the MOCCCIIs. Both of the novel universal current-mode active-C filters can simultaneously realize low-pass, band-pass and high-pass/notch filter responses. SPICE and MATLAB simulation results are given to verify the theoretical analysis.     

Regulatory reform in Turkish energy industry: An analysis

The Republic of Turkey has initiated an ambitious reform program in the most important segments of her energy market; which requires privatization, liberalization as well as a radical restructuring of these industries. However, there is no consensus that the measures introduced are optimal. The present article attempts, first, to evaluate the regulatory framework created by the laws of 2001 in terms of economic efficiency considerations; and second, to determine what still needs to be done to improve the current situation. The paper not only provides an analysis of these reforms but also lists some policy suggestions. The study concludes that despite relatively good legislative framework, in practice, the reforms in Turkey are far from ideal as they are mainly in the form of “textbook reforms”; and therefore a significant amount of work still lies ahead of Turkey to set up a fully fledged energy market.     

Novel floating simulated inductors with wider operating-frequency ranges

In this paper, a number of simulated floating inductors (FIs) employing second-generation current conveyor (CCII), current-feedback operational amplifier (CFOA), differential voltage current conveyor (DVCC) and differential difference current conveyor (DDCC) are proposed. They employ only a grounded capacitor; accordingly, they are suitable for integrated circuit (IC) implementation. Some of the developed FI simulators demonstrate the feature of improved low-frequency performance while the other ones suffer from the Z/Y terminal parasitic resistors bringing extra series resistors to the inductances of the simulated FIs. Two novel methods for reducing/eliminating the unwanted series resistance in equivalent inductances of the FIs are developed, one of which is called the direct design technique accomplished by adjusting the resistive component/components of the FIs. The series resistors of the FIs affecting their low-frequency performance can be canceled by adding floating negative resistors in series, which is another method. Three of the presented FIs as examples are chosen in order to verify the developed method, perform their simulations and show their performance.     

Study on the behavior of the trace metal and macro minerals in Mytilus galloprovincialis as a bioindicator species: the case of Marmara Sea, Turkey

Sea food is a major source of animal protein. Marine foods are very rich sources of mineral components. The total content of minerals in the raw flesh of marine fish and invertebrates is in the range of 0.6–1.5% wet weight. The contents of Na, K, Ca, Mg and P are up to 1 mg/100 g, whereas those of Fe, Zn, I are less than 1 mg/100 g. Mussels (Mytilus galloprovincialis) were investigated for macro and trace element composition throughout the year. Ranges of moisture, ash, protein and fat contents were 79.76–87.46 g/100 g, 1.06–2.06 g/100 g, 7.28–12.65 g/100 g and 0.33–3.49 g/100 g, respectively. While the highest protein and fat values were found in the summer (July–August), the highest moisture and ash contents were found in the winter (December–January). The contents of highest Na, K, Ca were found in the summer. Cadmium, lead and copper were found to be below the legislative limits throughout year. High levels of mercury were found in January and October. It should be discussed whether mussel may provide an alternative source of mineral for healthy nutrition.     

Defect Passivation in Perovskite Solar Cells by Cyano‐Based π‐Conjugated Molecules for Improved Performance and Stability

Defects at the surface and grain boundaries of metal–halide perovskite films lead to performance losses of perovskite solar cells (PSCs). Here, organic cyano‐based π‐conjugated molecules composed of indacenodithieno[3,2‐b]thiophene (IDTT) are reported and it is found that their cyano group can effectively passivate such defects. To achieve a homogeneous distribution, these molecules are dissolved in the antisolvent, used to initiate the perovskite crystallization. It is found that these molecules are self‐anchored at the grain boundaries due to their strong binding to undercoordinated Pb²⁺. On a device level, this passivation scheme enhances the charge separation and transport at the grain boundaries due to the well‐matched energetic levels between the passivant and the perovskite. Consequently, these benefits contribute directly to the achievement of power conversion efficiencies as high as 21.2%, as well as the improved environmental and thermal stability of the PSCs. The surface treatment provides a new strategy to simultaneously passivate defects and enhance charge extraction/transport at the device interface by manipulating the anchoring groups of the molecules.     

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。     

The microencapsulation of terbinafine via in situ polymerization of melamine‐formaldehyde and their application to cotton fabric

In this study an antifungal pharmaceutical agent, terbinafine, was microencapsulated by using in situ polymerization. The polymerization was carried out at four mole ratio level and preparations were applied to the 100% cotton fabric. X‐ray diffractometry, DSC, FTIR, BET, contact angle measurements, particle size distribution and imaging techniques were performed. Best results were obtained in the case of 8 : 1 mole ratio. Strength of microcapsule applied fabrics to washing and fungus were also determined. After 25 washing cycle, microcapsules were still in the fabric and had antifungal properties against A. niger. Antifungal strength against T. rubrum was observed up to 15 washing cycles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Classification of physiological disorders in apples fruit using a hybrid model based on convolutional neural network and machine learning methods

Neural Computing and Applications - Physiological disorders in apples are due to post-harvest conditions. For this reason, automatic identification of physiological disorders is important in...