Prototypical Hybrid System Research Articles

Enhancing the compatibility of abiotic and biological components for efficient nitrogen fixation

The realization of compatibility between the abiotic and biological components is critically important for building a successful hybrid biological/inorganic system. In this issue of Chem Catalysis , Lu et al. demonstrate a prototype hybrid system along with a unique methodology to enhance the communication between the abiotic and biological components for electrically converting N 2 /CO 2 into value-added chemicals.

Applications of Electron Beam to Environmental Conservation

The treatment of electron beam was tested for gaseous pollutants of volatile organiccompounds (VOCs), dioxin, and inorganic oxides (NOX and SOX). The representative VOCs of xylene and toluene were oxidized completely with electron beams using prototype hybrid system equipped with electron accelerator and MnO2 catalysts. More than 90% of dioxin in municipal solid waste incinerator gases was decomposed at a dose of 14 kGy. Nitrogen oxides and sulfur oxides in coal-fired flue gases were recovered as a fertilizer by the addition of NH3 under electron-beam irradiation.Electron beam is expected to be a promising method for treating gaseous pollutants.

Hybrid femtocell–attocell optical links for indoor free-space optical communication

The demand for wireless bandwidth is increasing rapidly; however, the throughput of short-range radio frequency (RF) solutions, such as WiFi, are quickly reaching limits due to limited bandwidth in the RF spectrum. This problem can be overcome by utilizing unregulated infrared wavelengths in the optical spectrum. On the other hand, free-space optical (FSO) communication presents a challenge for mobility due to the line-of-sight nature of optics. We present a dual-channel optical link for short-range FSO communication, which consists of a 100 Mb / s, large diameter (60 cm at 3 m distance) optical femtocell with a 1.5 Gb / s, small diameter (1 cm at 3 m distance) optical attocell embedded within the femtocell. This hybrid femtocell–attocell optical link addresses the needs of various users by providing a high mobility femtocell link combined with an enhanced bandwidth attocell hotspot. A prototype hybrid system was assembled and evaluated in terms of bandwidth, range, and bit error rate (BER). In addition, the relationship between the incident angle of the transmitted beam relative to the receiver and the BER of the received data was evaluated. At a communication distance of 3 m, the BER is

Hybrid Materials: Electronic and Optical Excitations at the Pyridine/ZnO(101¯0) Hybrid Interface (Adv. Theory Simul. 2/2019)

Hybrid systems, combining inorganic and organic components, present an ex-citing pathway towards tailoring materials with specific desired properties. By a first-principles approach based on many-body Green function techniques, in article number 1800108, Olga Turkina, Claudia Draxl, and co-workers explore the opto-electronic spectra of pyridine/ZnO(1010). In this prototypical hybrid system, various kinds of novel exciton types are formed. The image shows the hole probability distribution of a hybrid charge-transfer exciton.

Dynamics of Strong Coupling between J‐Aggregates and Surface Plasmon Polaritons in Subwavelength Hole Arrays

A prototypical hybrid system formed by strong coupled gold hole arrays and J‐aggregate molecules is investigated by using both steady‐state spectroscopic method and ultrafast pump‐probe approach. In particular, the plasmonic response of the device has been tuned by modifying its periodicity thus to achieve the strongest possible coupling regime. It is found that in the transient absorption spectra, under upper band excitation, the bleaching signal from uncoupled J‐aggregate molecules completely disappears. Instead, two distinctive period dependent bleaching bands are formed, clearly fingerprint of the hybrid exciton‐plasmon state. The dynamics of these bands is also directly analyzed. A remarkable long lifetime is found especially for the upper band, corresponding to the presence of a trap state in its transient absorption spectra under resonance excitation. Such unique feature should provide a new approach to control quantum‐mechanical states under coherent coupling.

Quantum Beats in Hybrid Metal–Semiconductor Nanostructures

We investigate nonradiative quantum coherence in the presence of coupling between excitons and surface plasmon polaritons (SPPs) in a hybrid metal–semiconductor nanostructure. In particular, we study how quantum coherence between heavy-hole (HH) and light-hole (LH) excitons in a GaAs quantum well (QW) is modified when they are coupled to SPPs of a gold grating. We find that the nonradative coherence is reduced in correlation with the coupling strength between the excitons and SPPs. Under the resonant coupling condition, the nonradiative coherence remains in the range of hundreds of femtoseconds, which is significantly longer than the plasmonic coherence. These experiments directly probe quantum dynamics in a prototypical hybrid system and provide critical information for exploring future quantum plasmonics applications.

Tracking oscillations in the presence of delay-induced essential instability

Hybrid testing, which couples physical experiments and computer simulations bidirectionally and in real-time, is a promising experimental technique in engineering. One fundamental problem of this technique are delays in the coupling between simulation and experiment. We discuss this issue for a simple prototype hybrid system: a pendulum that is vertically excited by coupling it to a simulated linear mass–spring–damper system. Under realistic conditions a small delay in the coupling can give rise to an essential instability: the linearisation has infinitely many unstable eigenvalues for arbitrarily small delay. This type of instability is impossible to compensate for with any of the standard compensation techniques. We introduce an approach based on feedback control and Newton iterations that is able to overcome this instability. The basic idea behind our approach consists of two parts. First, we change the bidirectional coupling between experiment and computer simulation to a unidirectional coupling and stabilise the experiment with a feedback loop. Second, we place the modified hybrid system into a Newton iteration scheme. If the iteration converges then the hybrid experiment behaves just as the original emulated system (within the experimental accuracy). We demonstrate, by using a computer simulation for the experimental part, that our approach is able to overcome the essential instability. In combination with path-following methods, it allows us to track oscillations and their bifurcations systematically.

Intermittency, metastability and coarse graining for coupled deterministic–stochastic lattice systems

We study the role of strong particle/particle interactions and stochastic fluctuations emanating from the micro-/sub-grid scale, in the context of a simple prototype hybrid system consisting of a scalar linear ordinary differential equation (ODE), coupled to a microscopic spin flip Ising lattice system. Due to the presence of strong interactions in the lattice model, the mean-field approximation of this system is a Fitzhugh–Nagumo-type system of ODE. However, microscopic noise and local interactions will significantly alter the deterministic and spatially homogeneous mean-field Fitzhugh–Nagumo behaviours (excitable, bistable and oscillatory) and will yield corresponding regimes with phenomena driven by the interaction of nonlinearity and noise across scales, such as strong intermittency, metastability and random oscillations. Motivated by these observations we consider a class of stochastic numerical approximations based on systematic coarse-grainings of stochastic lattice dynamics. The resulting stochastic closures give rise to computationally inexpensive reduced hybrid models that capture correctly the transient and long-time behaviour of the full system; this is demonstrated by detailed time series analysis that includes comparisons of power spectra and auto- and cross-correlations in time and space, especially in examples dominated by strong interactions between scales and fluctuations, such as nucleation, intermittent and random oscillation regimes.

A hybrid active/passive exhaust noise control system for locomotives

A prototype hybrid system consisting of active and passive components for controlling far-field locomotive exhaust noise has been designed, assembled, and tested on a locomotive. The system consisted of a resistive passive silencer for controlling high-frequency broadband noise and a feedforward multiple-input, multiple-output active control system for suppressing low-frequency tonal noise. The active system used ten roof-mounted bandpass speaker enclosures with 2-12-in. speakers per enclosure as actuators, eight roof-mounted electret microphones as residual sensors, and an optical tachometer that sensed locomotive engine speed as a reference sensor. The system was installed on a passenger locomotive and tested in an operating rail yard. Details of the system are described and the near-field and far-field noise reductions are compared against the design goal.

An energy efficient hybrid system of solar powered water heater and adsorption ice maker

A new hybrid system of solar powered water heater and adsorption ice maker has been proposed. The working principle of the combined cycles of solar refrigeration and heating is described, theoretical simulation to the thermodynamic processes has been made. Experiments have been performed in a developed prototype hybrid system; it is verified that the hybrid system is capable of heating 60 kg water to about 90°C as well as producing ice at 10 kg per day with a 2-m 2 solar collector.