The optimization performance of cross‐linked sodium alginate polymer electrolyte bio‐membranes in passive direct methanol/ethanol fuel cells

Consumption of methanol and ethanol as a fuel in the passive direct fuel cells technologies is suitable and more useful for the portable application compared with hydrogen as a preliminary fuel due to the ease of management, including design of cell, transportation, and storage. However, the cost production of commercial membrane is still far from the acceptable commercialization stage. Based to our previous works, the low cost of cross‐linked sodium alginate (SA) polymer electrolyte bio‐membrane shown the virtuous chemical, mechanical, and thermal characterization as polymer electrolyte membrane in the direct methanol fuel cells (DMFCs). This study will further the investigation of cross‐linked SA polymer electrolyte bio‐membrane performance in the passive DMFCs and the passive direct ethanol fuel cells (DEFCs). The experimental study investigates the influence of the membrane thickness, loading of catalysts, temperature, type of fuel, and fuel concentration in order to achieve the optimal working operation performances. The passive DMFCs is improved from 1.45 up to 13.5 mW cm^?2 for the maximum peak of power density, which is obtained by using 0.16 mm as an optimum thick of SA bio‐membrane that shown the highest selectivity 6.31 10⁴ S s cm^?3, 4 mg cm^?2 of Pt‐Ru as an optimum of anode catalyst loading, 2 mg cm^?2 of Pt at the cathode, 2M of methanol as an optimum fuel concentration, and an optimum temperature at 90°C. Under the same conditions of cells, the passive DEFCs are shown to be 10.2 mW cm^?2 in the maximum peak of power density with 2M ethanol. Based on our knowledge, this is the first work that reports the optimization works of performance SA‐based membrane in the passive DMFCs via experimental studies of single cells and the primary performance of passive DEFCs using the SA‐based membrane as polymer electrolyte membrane.     

Enhanced alkaline stability and performance of alkali‐doped quaternized poly(vinyl alcohol) membranes for passive direct ethanol fuel cell

Direct ethanol fuel cells (DEFCs) emerge as the new research energy field since fast production of electricity, high efficiency conversion, and simple fabrication process. The production cost, conductivity properties, and ethanol permeability of membrane were the main problem that limited the DEFC performance and commercialization. In this study, a low cost, good ionic conductivity and low ethanol permeability of an anion exchange membrane based on incorporation KOH‐doped quaternized poly(vinyl alcohol) (QPVA) membrane (designed as QPVA/KOH) is synthesized and cross‐linked with glutaraldehyde solution. The membrane is expected to cut the production cost and enhance the performance. In this work, an optimum of alkali‐doped concentration has influence the membrane performance. The membrane has reveal high chemical stability even doped with 8‐M KOH solution in 100°C. The morphology of membranes remained unbreakable and achieved high range of ionic conductivity (~10^?2 S cm^?1). The membranes present maximum ionic conductivity 1.29 × 10^?2 S cm^?1 at 30°C and 3.07 × 10^?2 S cm^?1 at 70°C. The ethanol permeability of membrane is lower compared with the commercial membranes. Power density of alkaline DEFCs with platinum‐based catalyst by using cross‐linked QPVA/KOH membrane is 5.88 mW cm^?2, which is higher than commercial membranes at 30°C temperature. At 70°C, power density has increased up to 11.28 mW cm^?2 and significantly increased up to 22.82 mW cm^?2 via the nonplatinum‐based catalyst. Moreover, according to the durability test, the performance of passive alkaline DEFC by using cross‐linked QPVA/KOH membrane has maintained at 36.2% level. With such efficiency, the stack current density has been able to stay above 120 mA cm^?2 for over 1000 hours, at 70°C.     

Enhanced mechanical flexibility and performance of sodium alginate polymer electrolyte bio‐membrane for application in direct methanol fuel cell

A new membrane was synthesized containing pure alginate, crosslinking agent (CaCl₂), and plasticizer (glycerol). Characterization studies of the membrane were applied to determine the characteristics and morphology using field emission scanning electron microscope, EDX, FTIR, XRD, and atomic force microscopy analysis. The half‐cell performance test of the membrane was verified by several tests, including proton conductivity and methanol permeability. The best membrane had high proton conductivity (10.1 × 10^?3 S cm^?1) and very low methanol permeability (1.984 × 10^?7 cm² s^?1), which consequently resulted in very high selectivity (5.0907 × 10⁴ Ss cm^?3). Glycerol had a positive modification and good influence on the alginate characteristics. Furthermore, the poor mechanical properties of the alginate biopolymer were enhanced by calcium chloride and glycerol inside the polymer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46666.     

Field pattern characteristics of GPR antennas

Sub-surface radar has become increasingly popular for carrying out completely non-invasive integrity tests on concrete structures. Commercial systems are available with a range of antenna frequencies that may be selected for an investigation. The choice of a particular antenna frequency is often a compromise between the physical size of the antenna and the penetration and resolution capabilities provided by the antenna. However, there is an interaction between a surface contact antenna and the substrate under investigation that will alter the field pattern being transmitted that may have significant implications for interpretation of results. An experimental programme is described in which the characteristics of commercially available 900 MHz and 1 GHz antennas are compared in air and when in contact with concrete and water surfaces, together with an emulsion used in previous studies to simulate the radar properties of concrete. Results are presented showing the influence of the material being measured upon the signal divergence. These effects are considered in terms of the practical implications for field-testing using radar.     

Correction to: Enhanced critical current density of ex situ MgB2 via control of Mg assisted sintering

Journal of Materials Science: Materials in Electronics -     

Recent advances in additive‐enhanced polymer electrolyte membrane properties in fuel cell applications: An overview

Additives such as fillers, cross‐linkers, and plasticizers have become increasingly important in the polymer nanocomposite production field, especially for enhancing the structural morphology, functional behavior, and final performance of nanocomposites in broad applications. The current work is an overview of the effects of additive substances such as fillers, cross‐linkers, and plasticizers in the polymer electrolyte membrane composites applied to fuel cells. A comparative review is conducted by categorizing fillers into several types, and the most popular cross‐linkers and plasticizers used in fuel cell membranes are included in this review. The highlighted properties include the proton conductivity, permeability, mechanical properties, thermal properties, crystallinity, and structure of additive‐modified nanocomposites. Furthermore, the challenges and future prospects in the additive field are discussed in Section 5.0. This review can provide a reference for researchers seeking specific substances that can be used to enhance nanocomposite properties, especially in membrane fuel cell applications.     

Expectations about arousal and nocturnal panic.

Expectations about arousal were examined in relation to nocturnal panic (NP). Eighteen panic disorder patients suffering from NP attacks and 18 control individuals were assigned randomly to conditions in which they were informed that audio feedback signals reflected heightened arousal that was either (a) expected and harmless or (b) unexpected. Participants relaxed and slept for 45 to 60 min, followed by presentation of periodic audio feedback signals. Physiological recording was continuous while subjective measures were collected at completion of the signals phase. NP patients in the unexpected-no reassurance condition were significantly more anxious and symptomatic than their counterparts in the expected reassurance condition, whereas control individuals did not differ across the 2 conditions. Physiological and behavioral data were less consistent than subjective measures. The results are interpreted as supportive of a cognitive–behavioral model of NP. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An intelligent method for sizing optimization in grid-connected photovoltaic system

This paper presents an intelligent sizing technique for sizing grid-connected photovoltaic (GCPV) system using evolutionary programming (EP). EP was used to select the optimal set of photovoltaic (PV) module and inverter for the system such that the technical or economic performance of the system could be optimized. The decision variables for the optimization process are the PV module and inverter which had been encoded as specific integers in the respective database. On the other hand, the objective function of the optimization task was set to be either to optimize the technical performance or the economic performance of the system. Before implementing the intelligent-based sizing algorithm, a conventional sizing model had been presented which later led to the development of an iterative-based sizing algorithm, known as ISA. As the ISA tested all available combinations of PV modules and inverters to be considered for the system, the overall sizing process became time consuming and tedious. Therefore, the proposed EP-based sizing algorithm, known as EPSA, was developed to accelerate the sizing process. During the development of EPSA, different EP models had been tested with a non-linear scaling factor being introduced to improve the performance of these models. Results showed that the EPSA had outperformed ISA in terms of producing lower computation time. Besides that, the incorporation of non-linear scaling factor had also improved the performance of all EP models under investigation. In addition, EPSA had also shown the best optimization performance when compared with other intelligent-based sizing algorithms using different types of Computational Intelligence.     

On the Performance of Various 5G Signals Sensing Based on Hybrid Filter

International Journal of Wireless Information Networks - The 5G wireless communication system is promised to exploit many kinds of waveform for satisfying various requirements to transmit huge size...