Multi-Channel Active Noise Control System Designs with Fuzzy Logic Stabilized Algorithms

Abstract. In active noise control filter, IIR filter structure which used for control filter assures the stability property. The stability characteristics of IIR filter structure is mainly determined by pole location of control filter within unit disc, so stable selection of the value of control filter coefficient is very important. In this paper, we proposed novel adaptive stabilized Filtered_U LMS algorithms with IIR filter structure which has better convergence speed and less computational burden than conventional FIR structures, for multi-channel active noise control with vehicle enclosure signal case. For better convergence speed in adaptive algorithms, fuzzy LMS algorithms where convergence coefficient computed by a fuzzy PI type controller was proposed. Multi-channel Active Noise control systems Unwanted acoustic noise problems become more and more evident as increased numbers of large industrial equipment such as engines, blowers, fans, transformers, and compressors are in use. Mechanical vibration is another related type of noise that commonly creates problems in all areas of transportation and manufacturing, as well as many household appliances. The traditional approach to acoustic noise control use passive techniques such as enclosures, barriers, and silencers to attenuate the undesired noise. These passive silencers are valued for their high attenuation over broad frequency range, but they are relatively large, costly, and ineffective at low frequencies. The attenuation of passive silencers is low when the acoustic wavelength is large compared to the silencer dimensions, such as body length or lining thickness. ANC systems utilizing a microphone and an electronically driven loud speaker to generate a canceling sound was first proposed in a 1936 patent by Lueg In active noise control filter, IIR filter structure which used for control filter assures the stability property. The stability characteristics of IIR filter structure is mainly determined by pole location of control filter within unit disc, so stable selection of value of control filter coefficient is very important. In this paper, we proposed novel adaptive stabilized fuzzy Filtered_U LMS algorithms with IIR filter structure which has better convergence speed and less computational burden than conventional FIR structures, for multi-channel active noise control with vehicle enclosure signal case

Carbon-based asymmetric capacitor for high-performance energy storage devices

Carbon-based materials are widely used in energy storage research, as attractive materials with high conductivity, low cost, and high availability. However, a relatively low performance (e.g., energy and power densities) compared with metal oxides is an obstacle to use for commercial applications. Herein, we report on high-performance metal oxide-free asymmetric capacitors (ASCs) using n-type and p-type graphene films which are doped by nitrogen and boron atoms, respectively, exhibiting high energy and power densities with excellent stability. The enhanced performances of the ASCs arises from the synergistic effect of the non-faradaic capacitance and pseudocapacitance, which are confirmed with new analysis using cyclic voltammetry and electrochemical impedance spectroscopy for a pseudocapacitance effect of intercalation/deintercalation and galvanostatic charge-discharge profiles for and non-faradaic capacitance. The new ASC in an ionic liquid electrolyte (e.g., pure EMIMBF4) shows the high energy density of 77.41 Wh kg−1 in 3.0 V of the operating potential window with the excellent retention stability of ∼87% after 10,000 cycles. The carbon-based asymmetric capacitor of semiconducting graphene electrodes can offer the promise of exploiting both non-faradaic capacitance and intercalation/deintercalation pseudocapacitance to obtain a high-performance energy storage device. © 2019 Elsevier Lt

Multi-Channel Active Noise Control System Designs with Fuzzy Logic Stabilized Algorithms

Abstract. In active noise control filter, IIR filter structure which used for control filter assures the stability property. The stability characteristics of IIR filter structure is mainly determined by pole location of control filter within unit disc, so stable selection of the value of control filter coefficient is very important. In this paper, we proposed novel adaptive stabilized Filtered_U LMS algorithms with IIR filter structure which has better convergence speed and less computational burden than conventional FIR structures, for multi-channel active noise control with vehicle enclosure signal case. For better convergence speed in adaptive algorithms, fuzzy LMS algorithms where convergence coefficient computed by a fuzzy PI type controller was proposed. Multi-channel Active Noise control systems Unwanted acoustic noise problems become more and more evident as increased numbers of large industrial equipment such as engines, blowers, fans, transformers, and compressors are in use. Mechanical vibration is another related type of noise that commonly creates problems in all areas of transportation and manufacturing, as well as many household appliances. The traditional approach to acoustic noise control use passive techniques such as enclosures, barriers, and silencers to attenuate the undesired noise. These passive silencers are valued for their high attenuation over broad frequency range, but they are relatively large, costly, and ineffective at low frequencies. The attenuation of passive silencers is low when the acoustic wavelength is large compared to the silencer dimensions, such as body length or lining thickness. ANC systems utilizing a microphone and an electronically driven loud speaker to generate a canceling sound was first proposed in a 1936 patent by Lueg In active noise control filter, IIR filter structure which used for control filter assures the stability property. The stability characteristics of IIR filter structure is mainly determined by pole location of control filter within unit disc, so stable selection of value of control filter coefficient is very important. In this paper, we proposed novel adaptive stabilized fuzzy Filtered_U LMS algorithms with IIR filter structure which has better convergence speed and less computational burden than conventional FIR structures, for multi-channel active noise control with vehicle enclosure signal case

A molecular approach to an electrocatalytic hydrogen evolution reaction on single-layer graphene

A major challenge in the development of electrocatalysts is to determine a detailed catalysis mechanism on a molecular level for enhancing catalytic activity. Here, we present bottom-up studies for an electrocatalytic hydrogen evolution reaction (HER) process through molecular activation to systematically control surface catalytic activity corresponding to an interfacial charge transfer in a porphyrin monolayer on inactive graphene. The two-dimensional (2D) assembly of porphyrins that create homogeneous active sites (e.g., electronegative tetrapyrroles (N4)) on graphene showed structural stability against electrocatalytic reactions and enhanced charge transfer at the graphene-liquid interface. Performance operations of the graphene field effect transistor (FET) were an effective method to analyse the interfacial charge transfer process associated with information about the chemical nature of the catalytic components. Electronegative pristine porphyrin or Pt-porphyrin networks, where intermolecular hydrogen bonding functioned, showed larger interfacial charge transfers and higher HER performance than Ni-, or Zn-porphyrin. A process to create surface electronegativity by either central N-4 or metal (M)-N-4 played an important role in the electrocatalytic reaction. These findings will contribute to an in-depth understanding at the molecular level for the synergetic effects of molecular structures on the active sites of electrocatalysts toward HER1441sciescopu

Highly transparent and flexible supercapacitors using graphene-graphene quantum dots chelate

Nowadays, transparent and flexible energy storage devices are attracting a great deal of research interest due to their great potential as integrated power sources. In order to take full advantage of transparent and flexible devices, however, their power sources also need to be transparent and flexible. In the present work we fabricated new transparent and flexible micro-supercapacitors using chelated graphene and graphene quantum dots (GQDs) by a simple electrophoretic deposition (EPD) method. Through a chelate formation between graphene and GQDs with metal ions, the GQD materials were strongly adhered on an interdigitated pattern of graphene (ipG-GQDs) and its resulting porous ipG-GQDs film was used as the active material in the micro-supercapacitors. Amazingly, these supercapacitor devices showed high transparency (92.97% at 550 nm), high energy storage (9.09 μF cm-2), short relaxation time (8.55 ms), stable cycle retention (around 100% for 10,000 cycles), and high stability even under severe bending angle 45° with 10,000 cycles. © 2016 Elsevier Ltd126301sciescopu

Highly stable multi-layered silicon-intercalated graphene anodes for lithium-ion batteries

© 2020 Cambridge University Press. All rights reserved.To avoid degradation of silicon anodes in lithium-ion batteries (LIBs), the authors report a new two-dimensional multi-layered Si-intercalated rGO (rGO/Si) anode prepared by direct growth of Si into a porous multi-layered reduced graphene oxide (rGO) film. Direct Si deposition onto the porous rGO film allows the Si layers to be intercalated into the film via in situ replacement of the oxygen groups of the multi-layered graphene oxide (GO) with Si through thermal reduction of the GO film. The porous rGO acts as a cushion against the expansion of the Si layer during lithiation, preventing the Si from being pulverized and producing highly stable LIBs11Nsciescopu

Development of a SnS Film Process for Energy Device Applications

Tin monosulfide (SnS) is a promising p-type semiconductor material for energy devices. To realize the device application of SnS, studies on process improvement and film characteristics of SnS is needed. Thus, we developed a new film process using atomic layer deposition (ALD) to produce SnS films with high quality and various film characteristics. First, a process for obtaining a thick SnS film was studied. An amorphous SnS2 (a-SnS2) film with a high growth rate was deposited by ALD, and a thick SnS film was obtained using phase transition of a-SnS2 film by vacuum annealing. Subsequently, we investigated the effect of seed layer on formation of SnS film to verify the applicability of SnS to various devices. Separately deposited crystalline SnS and SnS2 thin films were used as seed layer. The SnS film with a SnS seed showed small grain size and high film density from the low surface energy of the SnS seed. In the case of the SnS film using a SnS2 seed, volume expansion occurred by vertically grown SnS grains due to a lattice mismatch with the SnS2 seed. The obtained SnS film using the SnS2 seed exhibited a large reactive site suitable for ion exchange

Fast diffusion supercapacitors via an ultra-high pore volume of crumpled 3D structure reduced graphene oxide activation

In order to obtain a high performance supercapacitor, there are several factors that must be achieved including a high specific surface area (SSA), high electrical conductivity, and a high diffusion rate of the electrolyte due to an appropriate pore volume. Herein, we report a high performance supercapacitor using activated non-stacked reduced graphene oxide (a-NSrGO) that has a high SSA (up to 999.75 m2 g-1) with intrinsic high graphene conductivity (1202 S m-1) and fast diffusion of the electrolyte. Due to a high total pore volume (5.03 cm3 g-1) and a wide pore size distribution from macro- to micropores (main pore width: 0.61 - 0.71 nm) in the a-NSrGO sheets, the as-prepared a-NSrGO electrode shows high specific capacitance (105.26 F g-1) and a short relaxation time (τ0 = 1.5 s) in a propylene carbonate (PC)-based organic electrolyte. A maximum energy density of 91.13 W h kg-1 and a power density of 66 684.73 W kg-1 were estimated in a fully packaged coin cell. The high performance of the a-NSrGO supercapacitors is attributed to their specific appearance and enlarged pore distribution with high SSA. © The Royal Society of Chemistry 2015113141sciescopu

Vertical Alignments of Graphene Sheets Spatially and Densely Piled for Fast Ion Diffusion in Compact Supercapacitors

Supercapacitors with porous carbon structures have high energy storage capacity. However, the porous nature of the carbon electrode, composed mainly of carbon nanotubes (CNTs) and graphene oxide (GO) derivatives, negatively impacts the volumetric electrochemical characteristics of the supercapacitors because of poor packing density (<0.5 g cm^–3). Herein, we report a simple method to fabricate highly dense and vertically aligned reduced graphene oxide (VArGO) electrodes involving simple hand-rolling and cutting processes. Because of their vertically aligned and opened-edge graphene structure, VArGO electrodes displayed high packing density and highly efficient volumetric and areal electrochemical characteristics, very fast electrolyte ion diffusion with rectangular CV curves even at a high scan rate (20 V/s), and the highest volumetric capacitance among known rGO electrodes. Surprisingly, even when the film thickness of the VArGO electrode was increased, its volumetric and areal capacitances were maintained