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991.
Analog integrated circuit design has as integral parts both analytical reasoning and numerical validation in the process from topology construction to sizing. Given a circuit topology, different circuit sizing results can be obtained from different processes of sizing inference. Sizing methods by simulation-based numerical searching have been a continuously studied subject. However, almost all approaches in this category require an overwhelming number of circuit simulations to arrive at an optimized sizing result. On the other hand, many published manual sizing methods by using the conventional device equations also require repeated SPICE simulations to correct the equation-based sizing results. This paper proposes a systematic gm/ID-based initial sizing method specifically customized for designing multiple-stage operational amplifiers (Op Amps). A main feature of the proposal is to use circuit-level design equations as constraints on the gm/ID table lookup method to substantially reduce the uncertainty in the sizing calculations. As a result, a significant amount of SPICE based correction work can be reduced to complete an initial sizing. The proposed sizing procedure includes a few regular sizing rules customized to the configuration of multi-stage Op Amps. We validate the proposed sizing method by application to several multi-stage Op Amp examples with a capacitive load or Miller compensation. Simulations have justified that the produced initial sizing results can achieve most of the prespecified design targets. 相似文献
992.
Photovoltaic performances of the bismuth-based solar cells are profoundly affected by the thin film quality of the photoactive layer. Herein, we report on various green solvent system to obtain the highly crystalline, pinhole free and homogeneously methylammonium bismuth iodide (MBI) active layer. The MBI structure prepared with tetrahydrofuran:2-ethoxy-ethanol (THF-2ETO) solvent system was found to have the best film quality. Adding 0.05 M 2ETO as the co-solvent is sufficient to produce high quality BiI3 and MBI thin films. According to the X-ray photoelectron spectroscopy (XPS) analyzes, we have demonstrated that there is an interaction between BiI3 and 2ETO according to the concentration of 2ETO added to the main THF. Our study clarifies the importance of THF-2ETO solvent system that can accelerate the evolution of the Bi-based solar cells by creating high-quality BiI3 or MBI thin films. 相似文献
993.
Chaonan Wang Yuliang Hu Liudong Xing Quanlong Guan Chunhui Yang Min Yu 《Quality and Reliability Engineering International》2021,37(5):1783-1795
Motivated by real-world applications of satellites and wireless sensor networks, this paper models and evaluates a dynamic k-out-of-n phase-AND mission system (k/n-PAMS). The mission task conducted by a k/n-PAMS involves multiple consecutive phases; the mission is successful as long as the task is successful in any of the phases. Due to factors, such as scheduled maintenance, location changes in task execution during different phases, and resource sharing with other tasks, the total number of available components n for the considered mission task and the required number of working components k may change from phase to phase. In addition, due to varying load and working environments, component failure time distributions are also phase dependent. This paper proposes an analytical modeling approach based on multivalued decision diagrams (MDDs) for assessing reliability of the considered k/n-PAMS. The approach encompasses a new and fast MDD model generation algorithm that considers behaviors of all the mission phases simultaneously based on node labeling. As demonstrated through empirical studies on k/n-PAMSs with different sizes (different numbers of phases and different numbers of system components), the proposed algorithm is more efficient than the traditional phase-by-phase model generation method. 相似文献
994.
Sunhye Yang Kamrun Nahar Fatema Ick-Jun Kim Jihyeon Ryu Sang Eun Shim Won-Chun Oh 《Advanced Powder Technology》2021,32(4):1116-1126
This paper reports the synthesis of various molar concentrations of manganese (Mn)-doped Ultra-High Surface area Activated Carbon (USAC) additives and their efficient use as cathode materials for supercapacitors. We synthesized the nanoparticles via a novel and facile dip-coating process and characterized them in detail by various analytical techniques. The SEM, EDAX, and XPS results showed that the Mn ions were successfully substituted on the USAC additives’ layered structure without any structural changes. The long cyclic stability of the as-prepared Mn-doped USAC additives was tested as a cathode material for supercapacitors at different current densities. The detailed experimental results showed that the Mn dopant content crucially determines the electrochemical performances of the USAC additives. Electrochemical measurements showed that the MnCEP-S600HTT with 0.10 mol% molar concentration of Mn dopant gives the best cycling performances. It delivers a discharge capacity of 262.9 mAh g?1 after 100 cycles. Further increasing the current density to 1000 mA g?1 allowed it to still maintain 253.6 mAh g?1 after 200 cycles. We confirmed that the structure of Mn-doped USAC additives is an important pole to improve the structural stability and electrochemical properties. 相似文献
995.
In this study,the permeabilities of Berea and Otway sandstones were measured under different confining pressures,and porosity was investigated through mercury intrusion porosimetry(MIP).The total porosities of the Berea and Otway sandstones were approximately 17.4%and 25%,respectively.Pore size distributions of each sandstone were almost the same,but the pores in the Otway sandstone were slightly narrower.However,the permeability of the Otway sandstone was smaller than that of the Berea sandstone by one order of magnitude.Three-dimensional(3D)void geometry and geometrical properties of the void spaces relevant to flow were compared to obtain the relation between the permeability differences and porosities of the two sandstones.The 3D geometrical analysis using microfocus X-ray computed tomography(CT)was performed,and the pore geometries of both sandstones were compared using the 3D medial axis(3DMA)method.Pore and throat radii,pore coordination number,tortuosity,number of connecting paths,connecting path volume,and other factors were determined using 3DMA.The Otway sandstone was characterized by a small effective throat/pore radius ratio.Based on the fluid flow mechanism,the lower effective throat/pore radius ratio results in a lower permeability induced by the fluid energy loss,which means that the 3D geometrical shape of void spaces affects the permeability value. 相似文献
996.
The aim of this study is to reduce the phosphate concentration in treated wastewater using a small amount of the reactive filter media, Filtralite P. Biologically treated wastewater was passed through a filter with 215 g of Filtralite P. In the laboratory, the phosphate removal efficiency was 51% at a flow speed of 0.87 m/h. Under real conditions, in an experimental stand filled with 0.5 m3 of Filtralite P, the phosphate removal efficiency was 85% and the removal efficiency of total suspended solids was 57% after a 5‐month period. The residual phosphate concentration in the filtrate from the experimental stand was 1 mg/L of PO4‐P after the 5‐month period. The experimental filtration plant was buried in the ground, and it did not freeze and worked well under winter conditions. The results of this study can be useful in the design and development of tertiary wastewater treatment plants in view of their sustainability potential. 相似文献
997.
Amani Al-Othman Paul Nancarrow Muhammad Tawalbeh Ahmad Ka'ki Karim El-Ahwal Bassam El Taher Malek Alkasrawi 《International Journal of Hydrogen Energy》2021,46(8):6100-6109
Composite membranes composed of zirconium phosphate (ZrP) and imidazolium-based ionic liquids (IL), supported on polytetrafluoroethylene (PTFE) were prepared and evaluated for their application in proton exchange membrane fuel cells (PEM) operating at 200 °C. The experimental results reported here demonstrate that the synthesized membrane has a high proton conductivity of 0.07 S cm?1, i.e, 70% of that reported for Nafion. Furthermore, the composite membranes possess a very high proton conductivity of 0.06 S cm?1 when processed at 200 °C under completely anhydrous conditions. Scanning electron microscopy (SEM) images indicate the formation of very small particles, with diameters in the range of 100–300 nm, within the confined pores of PTFE. Thermogravimetric analysis (TGA) reveals a maximum of 20% weight loss up to 500 °C for the synthesized membrane. The increase in proton conductivity is attributed to the creation of multiple proton conducting paths within the membrane matrix. The IL component is acting as a proton bridge. Therefore, these membranes have potential for use in PEM fuel cells operating at temperatures around 200 °C. 相似文献
998.
999.
John Fredy Vélez Santa Svit Menart Marjan Bele Francisco Ruiz-Zepeda Primož Jovanovič Vasko Jovanovski Martin Šala Milutin Smiljanić Nejc Hodnik 《International Journal of Hydrogen Energy》2021,46(49):25039-25049
Developing a Pt-based electrocatalytic material able to selectively catalyze hydrogen oxidation (HOR) while supressing oxygen reduction (ORR) is beneficial for durability of the fuel cells. Namely, degradation of carbon supported Pt particles is dramatically influenced by the unwanted ORR enrolling at the anode due to the air penetration during start-up/shut-down events. We present an organic matrix tris(aza)pentacene (TAP), which belongs to π-functional materials with ladder-like conjugated nitrogen-containing units, as the support for Pt to form a “smart” fuel cell anode able to selectively catalyze HOR and to suppress ORR. “Switching-on/off” of the composite material activity is provided by reversible reduction/oxidation of the TAP in the low potential region which provokes TAP - HxTAP transition. Conductivity of the reduced HxTAP enables supported Pt particles to effectively run HOR. In contrast, restricted conductivity of oxidized TAP analogue leads to the substantial drop in the ORR activity with respect to benchmark Pt/C catalyst. 相似文献
1000.
Kandi Sridhar Albert Linton Charles 《International Journal of Food Science & Technology》2021,56(4):1937-1945
Grape (Kyoho) skin, used to retard lipid oxidation in edible oil foods, was investigated to reduce lipid oxidation in an oil-in-water (O/W) emulsion during 20 day of storage. The antioxidant efficacy of Kyoho skin extracts in O/W emulsions was determined by the measurement of secondary oxidation products. Moreover, principal component analysis (PCA) was conducted to determine similarities between emulsions treated with or without Kyoho skin extracts and standards. The data revealed that Kyoho skin extracts exhibited >93% inhibition and reported a similar p-anisidine (4.30–20.71) and TBARS (6.08–11.15 mg MDA L−1) values over the standards during 20 day of storage. PCA (PCs 1 (51.83%) and 2 (18.85%)) demonstrated a similarity in the contribution of Kyoho skin extracts over the synthetic antioxidants in O/W emulsion. Overall, these findings highlighted the possibility of using Kyoho skin extracts as natural antioxidants to decrease oxidative rancidity in foods. 相似文献