Nonlinear phenomena are studied in such disciplines as meteorology, engineering, oceanography and astrophysics. In this Letter, we study a (3+1)-dimensional Korteweg-de Vries equation in a fluid. By ...virtue of the long-wave-limit method, the higher-order rational solutions are given. Based on the first-order rational solutions, we convert a lump into a line-rogue wave under certain condition. We investigate the effects of the coefficients in the equation for the velocities and amplitudes on the lump and line-rogue wave. Interactions between two line-rogue waves/one lump and one line-rogue wave are worked out with the second-order rational solutions. Through the characteristic-line analysis, we convert the breathers into five different types of the transformed nonlinear waves. Based on certain semi-rational solutions, interactions between the line-rogue wave and soliton/breather/transformed nonlinear wave are graphically illustrated.
•A (3+1)-dimensional Korteweg-de Vries equation in a fluid has been considered in this Letter.•Based on the long-wave-limit method, the lumps have been converted into the line-rogue waves.•Effects of the coefficients in the equation for the characteristics on the line-rogue wave have been studied.•Via the characteristic-line analysis, breathers have been converted into the transformed nonlinear waves.•Interactions between the line-rogue wave and soliton/breather/transformed nonlinear wave have been depicted.
Microwave pyrolysis using a well-mixed bed of activated carbon as both the microwave absorber and reaction bed was investigated for its potential to recover useful products from waste palm cooking ...oil – a cooking oil widely used in Asia. The carbon bed provided rapid heating (∼18 °C/min) and a localized reaction hot zone that thermally promoted extensive pyrolysis cracking of the waste oil at 450 °C, leading to increased production of a biofuel product in a process taking less than 25 min. It also created a reducing reaction environment that prevented the formation of undesirable oxidized compounds in the biofuel. The pyrolysis produced a biofuel product that is low in oxygen, free of sulphur, carboxylic acid and triglycerides, and which also contains light C10-C15 hydrocarbons and a high calorific value nearly comparable to diesel fuel, thus showing great potential to be used as fuel. This pyrolysis approach offers an attractive alternative to transesterification that avoids the use of solvents and catalysts, and the need to remove free fatty acids and glycerol from the hydrocarbon product. The pyrolysis apparatus operated with an electrical power input of 1.12 kW was capable of producing a biofuel with an energy content equivalent to about 3 kW, showing a positive energy ratio of 2.7 and ≥73% recovery of the energy input to the system. The results show that the pyrolysis approach has huge potential as a technically and energetically viable means for the recovery of biofuels from the waste oil.
•Waste palm oil was pyrolyzed by a microwave-heated bed of activated carbon.•The carbon bed provides rapid heating and thermally promotes pyrolytic cracking.•A reducing environment is created that prevents formation of oxidized by-products.•Biofuel is diesel-like, low in O2, free of sulphur, carboxylic acid, triglycerides.•The pyrolysis shows a positive energy ratio of 2.7 and an energy recovery of ≥73%.
In this letter, new compact third-order single- and dual-band filters on a hexa-modes half-mode substrate integrated waveguide (HMSIW) resonator with loaded H-shaped slot are presented. For the ...single-band design, the TE 101 mode, TE 201 mode, and the lower part of H-shaped slot mode are utilized to realize the third-order filtering response. By properly allocating the high-order modes, wide-stopband performance is also obtained. For the dual-band design, the TE 101 mode, TE 201 mode, and the lower part of H-shaped slot mode are used to realize the third-order lower passband, and the TE 202 mode, TE 302 mode, and the upper part of H-shaped slot mode are used to realize the third-order upper passband. The operating frequency and bandwidth of the proposed single-/dual-band filters both can be independently controlled. To validate the design concept, two prototypes of third-order single- and dual-band HMSIW bandpass filters (BPFs) are designed, fabricated, and tested. The simulated and measured results agree well with each other.
This article presents a basic 3-D frequency-selective surface (FSS) unit cell and its application for synthesis of high-order bandpass filtering response. The proposed FSS unit cell is constructed by ...stacked slotlines loading with shunted capacitive and/or inductive strip lines, which can be easily fabricated with traditional printed circuit board techniques. First, by analyzing the propagation characteristics of the stacked slotline, it can be found that the stacked slotline is seen as a transmission-line transformer, which can convert spatial electromagnetic waves into guided waves. Then, by loading shunted capacitive and/or inductive strip lines, equivalent capacitors and/or inductors are formed with the slotline section, which can be used to realize desirable resonators for bandpass filtering response. Equivalent circuit models are established and circuit parameters are extracted. With the aids of the generalized filter synthesis theory, the proposed unit cell is first applied to synthesize bandpass FSS with 1/4-wavelength transmission-line inverters. An example of a second-order Chebyshev bandpass FSS with the center frequency of 10 GHz is synthesized and designed. The measured results demonstrate that the desired bandpass filtering response is stable for oblique incidence. Furthermore, to obtain high-order response with a reduced FSS thickness, the proposed unit cell is then applied to synthesize bandpass FSS based on a lumped-element bandpass filter. The detailed synthesis procedure and derivations are given. Another example of a third-order Chebyshev bandpass FSS with the center frequency of 10 GHz is also designed, fabricated, and measured. The measured results show that the desired stable performance is realized and the total FSS thickness is <inline-formula> <tex-math notation="LaTeX">0.21\lambda _{0} </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">\lambda _{0} </tex-math></inline-formula> is the free-space wavelength at the center frequency).
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•Different types of intermediate reactions of hydroprocessing pathway were compared.•Single step hydroprocessing of biofuel are mainly done by deoxygenation.•Ni-impregnated zeolite ...catalyst favors the yielding of biofuel in deoxygenation.•Optimum reacting parameters of deoxygenation are kept at 350–400 °C and 1–5 MPa.
Present-day, commercial airlines are getting into the use of bio-jet fuel, by blending vegetable oil derived bio-jet fuel with fossil jet fuel in maximum up to 50%, which is ASTM-certified. In order to reduce the dependency on fossil jet fuel, recent research trend shows that most of the renewable aviation fuel or bio-jet fuel were derived from the complex liquid biomass via hydroprocessing technology. Hence there is a necessity to have an insight into the production technology, typically the hydroprocessing technology. Generally, hydroprocessing technology for the liquid biomass conversion into bio-jet fuel involved multi intermediate steps, such as deoxygenation, cracking and isomerization. This conventional process is further upgraded and simplified into single step reaction, which minimizes the post-treatment effort to be done in every reaction step, and thus reduces the production cost. Moreover, other economic factors such as catalyst price, hydrogen production cost and plant size will also consider as major impacts towards biofuel production scale and cost. Therefore, this paper aims to review the bio-jet fuel conversion technologies in a different perspective, by comparing the hydroprocessing technology of bio-jet fuel (i.e. three-step process, two-step process, single step process), and the effect of reaction variables (i.e. feedstock, catalyst, and reacting gas). The details of outputs for different hydroprocessing technology are also discussed herein. In summary, most research works have achieved positive findings in single step process, by adapting hydrodeoxygenation process in majority. However, there are some limitation and challenges that can be further improved in the single step process, such as exploration on potential feedstock, development of catalyst and optimization of reacting parameters. The energy, environmental and economic analysis on the advanced hydroprocessing of bio-jet fuel are yet to be conducted, in order to compare their merits.
In this letter, we propose a new class of phase shifter which can provide different constant phase shifts at two bands for the first time. The prescribed phase shifts <inline-formula> <tex-math ...notation="LaTeX">\Delta \Phi _{\mathbf {1}}({f}_{\mathbf {1}}) </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">\Delta \Phi _{\mathbf {2}}({f}_{\mathbf {2}}) </tex-math></inline-formula> and frequency ratio (<inline-formula> <tex-math notation="LaTeX">{n} ={f}_{\mathbf {2}}/{f}_{\mathbf {1}} </tex-math></inline-formula>) of the two bands can be obtained by the developed dual-band phase-shifting line on C-section. Meanwhile, the dual-band phase-slope alignment is first realized by virtue of the two groups of coupled resonators, resulting to independently control the phase slopes at two separated bands as required. The closed-form equations and design charts are further given. For verification, a prototype dual-band phase shifter operating at 3.0 and 5.4 GHz (<inline-formula> <tex-math notation="LaTeX">n = 1.8 </tex-math></inline-formula>) is designed, fabricated, and tested. The measured results show the proposed phase shifter exactly achieves prescribed constant phase shifts of 90° ± 2.3° over 2.76-3.31 GHz (18%) and 180° ± 2.7° over 4.97-5.80 GHz (15%). Both the simulation and measured results are recorded with good agreement.
Ammonia (NH3) has emerged as an attractive carbonless fuel that can be co-fired with hydrocarbon fuel to reduce carbon dioxide emissions. To understand the influence of NH3 on soot formation when ...co-fired with hydrocarbons, the soot formation propensity is experimentally investigated via a laminar diffusion jet flame. A stable ethylene (C2H4) jet flame doped with NH3 at different volume percentages was established for the investigation of soot formation tendency. OH* chemiluminescence imaging revealed the change of flame structure, in which the signals emitted from the heat release region weakened with increasing NH3 addition, while the peak intensity shifted from the flame wings towards flame centerline region. The laser extinction method used to measure the soot volume fraction (SVF) at different heights above the burner, which showed the effect of NH3 on soot suppression is significant, owing to the interaction between N-containing compounds with carbon atoms that result in the reduction of key intermediate products required for the formation of benzene and polycyclic aromatic hydrocarbons (PAH). The effect of soot inhibition appears to be stronger for the low NH3 blend fraction. The chemistry effect of NH3 on soot reduction for C2H4 flame is ascertained by comparing with N2-doped C2H4 flame at the same volume percentage. This work highlights the need for improved understanding of hydrocarbon fuel with NH3 to enable detailed understanding on the soot generation and oxidation process.
Besides the pandemic caused by the coronavirus outbreak, many other pathogenic microbes also pose a devastating threat to human health, for instance, pathogenic bacteria. Due to the lack of ...broad‐spectrum antibiotics, it is urgent to develop nonantibiotic strategies to fight bacteria. Herein, inspired by the localized “capture and killing” action of bacteriophages, a virus‐like peroxidase‐mimic (V‐POD‐M) is synthesized for efficient bacterial capture (mesoporous spiky structures) and synergistic catalytic sterilization (metal–organic‐framework‐derived catalytic core). Experimental and theoretical calculations show that the active compound, MoO3, can serve as a peroxo‐complex‐intermediate to reduce the free energy for catalyzing H2O2, which mainly benefits the generation of •OH radicals. The unique virus‐like spikes endow the V‐POD‐M with fast bacterial capture and killing abilities (nearly 100% at 16 µg mL–1). Furthermore, the in vivo experiments show that V‐POD‐M possesses similar disinfection treatment and wound skin recovery efficiencies to vancomycin. It is suggested that this inexpensive, durable, and highly reactive oxygen species (ROS) catalytic active V‐POD‐M provides a promising broad‐spectrum therapy for nonantibiotic disinfection.
A bioinspired, spiky, and highly catalytic‐active virus‐like peroxidase‐mimic (V‐POD‐M) is synthesized for the localized “capture and killing” eradication of pathogenic bacteria. Experimental and theoretical calculations demonstrate that the V‐POD‐M exhibits strong bacterial interactions and efficient capture, synergistic catalytic sterilization, and similar in vivo disinfection efficiency to that of vancomycin, which provides a promising broad‐spectrum therapy for nonantibiotic disinfection.
Metal oxides (MOs) have been widely investigated as promising high-capacity anode material for lithium ion batteries, but they usually exhibit poor cycling stability and rate performance due to the ...huge volume change induced by the alloying reaction with lithium. In this article, we present a double protection strategy by fabricating a two-dimensional (2D) core–shell nanostructure to improve the electrochemical performance of metal oxides in lithium storage. The 2D core–shell architecture is constructed by confining the well-defined graphene based metal oxides nanosheets (G@MO) within carbon layers. The resulting 2D carbon-coated graphene/metal oxides nanosheets (G@MO@C) inherit the advantages of graphene, which possesses high electrical conductivity, large aspect ratio, and thin feature. Furthermore, the carbon shells can tackle the deformation of MO nanoparticles while keeping the overall electrode highly conductive and active in lithium storage. As the result, the produced G@MO@C hybrids exhibit outstanding reversible capacity and excellent rate performance for lithium storage (G@SnO2@C, 800 mAh g–1 at the rate of 200 mA g–1 after 100 cycles; G@Fe3O4@C, 920 mAh g–1 at the rate of 200 mA g–1 after 100 cycles).
This article presents a synthesis method to design a new type of bandpass frequency selective surfaces (FSSs) with multiple transmission zeros (TZs). To briefly show the concept of our synthesis ...method, a generalized topology of the bandpass FSS based on cascaded slotline sections paralleled with bandpass resonators is first presented to map with an alternative <inline-formula> <tex-math notation="LaTeX">n </tex-math></inline-formula>th-order bandpass filtering network with <inline-formula> <tex-math notation="LaTeX">J </tex-math></inline-formula>-inverters and typical LC parallel resonators. Then, two kinds of composite LC parallel resonators, named as LC - LC and <inline-formula> <tex-math notation="LaTeX">{L} </tex-math></inline-formula> - LC parallel resonators, are introduced and discussed to replace the typical LC parallel resonators, which can produce TZs at skirts of the passband and increase the out-of-band selectivity. The derivations of equivalent relationships between the composite and typical LC resonators are given. Furthermore, for the exploration of bandpass FSS with multiple out-of-band TZs, the realization of these two discussed composite LC parallel resonators is exhibited by inductive and capacitive strip lines loading on slotline structures. The design curves and guidelines are given and discussed correspondingly. To validate our design concept, two FSS examples, a second-order bandpass FSS with four out-of-band TZs and a third-order one with five out-of-band TZs, are synthesized and designed. In final, these two designed bandpass FSS prototypes are fabricated and then measured by the free-space measurement method. The measured results show that the desired stable bandpass filtering performance and independently multiple out-of-band TZs are successfully realized.
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