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Conjugated polymers have attracted much attention for many years and have applications in various organic devices. Carbon nanotubes can be considered as all-carbon tube-shaped conjugated polymers containing only sp

Conjugated polymers have attracted much attention for many years and have applications in various organic devices. Carbon nanotubes can be considered as all-carbon tube-shaped conjugated polymers containing only sp2-bonded atoms, which play an important role in nanotechnology and nanoelectronics. So far, no study has reported the realization of long π-conjugated polymers as diameter-specified carbon nanotube segments. Herein, we report the first synthesis of a π-conjugated polymeric segment (PS1) of armchair single-walled carbon nanotubes. PS1 is achieved by a rationally designed synthesis of a bifunctionalized cyclo-para-phenylene monomer, followed by inserting these ring-shaped units into the conjugated poly-para-phenylene backbone. Our PS1 was fully characterized by gel permeation chromatography (GPC) combined with NMR, FTIR, and Raman spectra. Its photophysical and unique electronic properties were also investigated. Possessing unique structural and physical properties, this long π-extended polymer PS1 can provide new insight for the development of bottom-up syntheses of uniform carbon nanotube segments and potential applications in electron-transport devices.

Herein, we explore phenanthrene as the building block to synthesize a hoop-shaped [6,6]carbon nanotube segment from a planar macocycle via a Diels-Alder reaction. The phenanthrene-based coronal nanohoop

The conventional Kalman filter (KF) which uses the current measurement to estimate the current state is a posterior estimation. KF is identified as the optimal estimation in linear models with Gaussian noise. However, the performance of KF with incomplete information may be degraded or diverged. In order to improve the performance of KF, an Amended KF (AKF) is proposed by using more posterior measurements. The principle, derivation and recursive process of AKF are presented. The differences among Kalman smoother, adaptive fading method and AKF are analyzed. The simulation results of target tracking with different covariance of motion model indicate the high precision and robustness of AKF.

Herein, we report a facile method of direct photodissociation of toluene molecules to photoluminescent carbon dots (CDs) under pulsed laser irradiation in the absence of surfactants or catalysts. The as-synthesized CDs with diameters 1.3–4.0 nm present regular emission peaks and the crystallographic structure of these species has been identified as graphite 2H from the analysis of high resolution transmission electron microscope (HRTEM) images, X-ray photoelectron spectroscopy (XPS) and Raman spectrum. In addition, First-Principle calculations were performed to discuss the photon-induced excitation in the photodissociation process. The results demonstrate that electrons can be transited from Highest Occupied Molecular Orbital (HOMO) to Lowest Unoccupied Molecular Orbital (LUMO) in toluene molecule by 248 nm single photon excitation process and the Stark effect plays a crucial role in the photodissociation process. These CDs exhibit excellent stable emission due to the stability of crystal structure, which could be considered for promising luminescent applications.

Photovoltaics is amongst the most important technologies for renewable energy sources, and plays a key role in the development of a society with a smaller environmental footprint. Key parameters for solar cells are their energy conversion efficiency, their operating lifetime, and the cost of the energy obtained from a photovoltaic system compared to other sources. The optimization of these aspects involves the exploitation of new materials and development of novel solar cell concepts and designs. Both theoretical modeling and characterization of such devices require a comprehensive view including all scales from the atomic to the macroscopic and industrial scale. The different length scales of the electronic and optical degrees of freedoms specifically lead to an intrinsic need for multiscale simulation, which is accentuated in many advanced photovoltaics concepts including nanostructured regions. Therefore, multiscale modeling has found particular interest in the photovoltaics community, as a tool to advance the field beyond its current limits. In this article, we review the field of multiscale techniques applied to photovoltaics, and we discuss opportunities and remaining challenges. © T. Abu Hamed et al., published by EDP Sciences, 2018., European Cooperation in Science and Technology: MP1406, The authors are grateful for the financial support by the COST Action MP1406 “MultiscaleSolar.”

A green and efficient synthesis of aqueous CdTe quantum dots (QDs) embedded in inorganic salt enabled by co-precipitation is demonstrated, providing a new type of solid-state conversion material with emission colors covering green to red spectral regions. CdTe QDs were synthesized in the water phase, followed by incorporation into inorganic salt with the assistance of ethanol. Due to the protection of the tight matrix, the resulting composites exhibit good stability and processability as well as high photoluminescence properties. A white light emitting diode (WLED) applying the composites as a red color conversion layer with good luminescence properties is also fabricated, suggesting the promising application of the composites in solid-state lighting systems.

By using the Lyapunov second method, the robust control and robust optimal control for the gas tungsten arc welding dynamic process whose underlying continuous-time systems are subjected to structured uncertainties are discussed in time-domain. As results, some sufficient conditions of robust stability and the corresponding robust control laws are derived. All these results are designed by solving a class of linear matrix inequalities (LMIs) and a class of dynamic optimization problem with LMIs constraints respectively. An example adapted under some experimental conditions in the dynamic process of gas tungsten arc welding system in which the controlled variable is the backside width and controlling variable welding speed, is worked out to illustrate the proposed results. It is shown in the paper that the sampling period is the crucial design parameter

A novel type of aqueous fluorescent carbon dot (CD) was synthesized using citric acid as the only carbon source via an ammonium hydroxide modulated method, providing a blue color gamut. The amino group is considered to be the key factor in the high fluorescence of CDs and a model is established to investigate the mechanism of fluorescence. In addition, white light-emitting diodes (WLEDs) are fabricated by utilizing the prepared CDs and rare earth luminescent materials (SrSi2O2N2:Eu and Sr2Si5N8:Eu) as color conversion layers and UV-LED chips as the excitation light source. The WLEDs produce bright white light with attractive color rendering properties including a color rendering index of up to 95.1, a CIE coordinate of (0.33, 0.37), and a T c of 5447 K under a 100 mA driven current, indicating that the CDs are promising in the field of optoelectronic devices.

An adaptive method of helicopter track and balance is introduced to improve the search for the required blade adjustments. In this method, an interval model is used to represent the range of effect of blade adjustments on helicopter vibration, instead of exact values, to cope with the nonlinear and stochastic nature of aircraft vibration. The coefficients of the model are initially defined according to sensitivity coefficients between the blade adjustments and helicopter vibration, to include the ‘a priori’ knowledge of the process. The model coefficients are subsequently transformed into intervals and updated after each tuning iteration to improve the model’s estimation accuracy. The search for the required blade adjustments is performed according to this model by considering the vibration estimates of all of the flight regimes to provide a comprehensive solution for track and balance. The effectiveness of the proposed method is evaluated in simulation using a series of neural networks trained with actual vibration data. The results indicate that the proposed method improves performance according to several criteria representing various aspects of track and balance.

A two-wheeled self-balancing robot with a fuzzy PD control method is described and analyzed as an example of a high-order, multiple-variable, nonlinear, strong-coupling, and unstable system. Based on a system structure model, a kinetic equation is constructed using Newtonian dynamics and mechanics. After a number of simulation experiments, we get the best Q, R, and state-feedback matrices. Then a fuzzy PD controller is designed for which the position and speed of the robot are inputs and for which the angle and angle rate of the robot are controlled by a PD controller. Finally, this paper describes a real-time control platform for the two-wheeled self-balancing robot that controls the robot effectively, after some parameter debugging. The result indicates that the fuzzy PD control algorithm can successfully achieve self-balanced control of the two-wheeled robot and prevent the robot from falling.

In this paper, a rear-end collision control model is proposed using the fuzzy logic control scheme for the autonomous or cruising vehicles in Intelligent Transportation Systems (ITSs). Through detailed analysis of the car-following cases, our controller is established on some reasonable control rules. In addition, to refine the initialized fuzzy rules considering characteristics of the rear-end collisions, the genetic algorithm is introduced to reduce the computational complexity while maintaining accuracy. Numerical results indicate that our Genetic algorithm-optimized Fuzzy Logic Controller (GFLC) outperforms the traditional fuzzy logic controller in terms of better safety guarantee and higher traffic efficiency.

Method of angular strobe and tracking to Jammers for passive monopulse seeker is presented. In the case of two wideband noise frequency modulation (FM) jammers within main beam, firstly, the angular extent parameter is used to detect the presence of two jammers. Secondly, angular resolving of the two jammers is realized by using the clustering analysis. Thirdly, angular strobe of the two jammers is realized by using the dynamic clustering algorithm. Finally, seeker can track a selected jammer by using main beam angular compress.

A method of helicopter track and balance is introduced that uses a forward-model to search for the appropriate blade modifications. This method uses an interval model to represent the ranges of effects of blade modifications on helicopter vibration, instead of exact values, in order to cope with the stochastic nature of aircraft vibration. The coefficients of the interval model are initially defined according to sensitivity coefficients between the blade modifications and helicopter vibration, but they are subsequently updated after each tuning iteration to improve the model’s estimation accuracy. The effectiveness of the proposed method is demonstrated through a simulation model that represents experimental vibration measurements of Black Hawk helicopters.Copyright © 2002 by ASME